TWI765284B - Isomerization processes for converting aromatic hydrocarbons comprising alkyl-demethylation - Google Patents

Abstract

Alkyl-demethylation of C2+-hydrocarbyl substituted aromatic hydrocarbons can be utilized to treat one or more of a heavy naphtha reformate stream, a hydrotreated SCN stream, a C8 aromatic hydrocarbon isomerization feed stream, a C9+ aromatic hydrocarbon transalkylation feed stream, and similar hydrocarbon streams to produce additional quantity of xylene products.

Description

Isomerization Process for Converting Aromatic Hydrocarbons Involving Alkyl-Demethylation

The present disclosure relates to methods of converting aromatics, such as methods of making xylenes, isomerizing C8 aromatics, and transalkylating aromatics. In particular, the present disclosure relates to such methods comprising alkyl-demethylation of aromatic hydrocarbons having C2+-alkyl substituents attached to or fused to aromatic rings therein Cyclic aliphatic ring. The present disclosure can be used to produce, for example, xylenes (eg, para-xylene, ortho-xylene, and/or mixed xylenes) from naphtha reformer effluents and/or hydrotreated steam cracked petroleum naphtha streams produced in petrochemical plants. toluene). [Related References to Related Applications]

This application claims the priority and benefit of U.S.S.N. 62/876,426 filed on July 19, 2019 and European Patent Application No. 19199461.5 filed on September 25, 2019, the disclosures of which are incorporated herein by reference .

Para-xylene ("p-xylene") is an important industrial commodity in the manufacture of terephthalic acid, which was later used in the manufacture of large quantities of polyester fibers. Ortho-xylene ("o-xylene") is another important industrial commodity in the manufacture of phthalic acid, which was later used in the manufacture of plasticizers and other industrial materials . Large amounts of para-xylene and ortho-xylene are consumed worldwide every year. The high demand for these two aromatics has led to the upgrading of many of their mass production technologies. O-xylene and para-xylene are frequently present in C8 aromatic mixtures, which also contain their isomers, which include inter-xylene and ethylbenzene in various amounts. Separation of the para-xylene product from such C8 aromatic hydrocarbon mixtures can be accomplished using techniques such as crystallization and adsorption chromatography based techniques. The residual filtrate from the crystallization separation process and the raffinate from adsorption chromatography-based techniques (collectively referred to as "raffinate") are para-xylene depleted and meta- and ortho-xylene rich. Typically, the raffinate is then isomerized in contact with an isomerization catalyst in an isomerization reactor to convert a portion of the meta- and ortho-xylene to para-xylene, which can be separated in the xylene loop. Additional paraxylene.

In petrochemical plants, the major source of C8 aromatic mixtures is the C6+ hydrocarbon reformed oil stream produced by heavy naphtha reformation reactors ("recombiners"). The paraffins and aromatics contained in the heavy petroleum naphtha feed supplied to the reformer undergo complex chemical reactions (such as isomerization, dehydrogenation, dehydrocyclization, aromatization, etc.) in the presence of a reforming catalyst and under reforming conditions ) to produce a reconstituted mixture containing more branched paraffins, aromatics, and hydrogen. The C6+ hydrocarbon reformed oil stream separated from the reformed mixture contains benzene, toluene, C8 aromatics, and C9+ aromatics. C8 aromatics typically contain significant amounts of ethylbenzene in addition to xylenes. C9+ aromatics typically include aromatics containing C2+ alkyl groups (eg, ethyltoluene, diethylbenzene, C3-alkylbenzenes, etc.) in addition to aromatics containing only methyl substituents attached to the aromatic ring therein etc.) and/or aromatic hydrocarbons comprising an aliphatic ring fused to an aromatic ring (eg, indene, methyldihydroindene, tetralin, methyltetrahydronaphthalene, etc.).

Thus, the raffinate derived from the reconstituted oil stream following the isomerization described above typically contains significant amounts of ethylbenzene. It is difficult to convert ethylbenzene directly to xylenes in an isomerization reactor. In order to prevent the accumulation of ethylbenzene in the xylene loop and convert ethylbenzene to more valuable products, a known strategy is to isomerize ethylbenzene under vapor phase conditions in the presence of a catalyst effective for deethylating ethylbenzene method. The ethyl groups removed from the ethylbenzene form light hydrocarbons in the isomerization reactor in the presence of hydrogen. Vapor phase isomerization is energy intensive. It would be beneficial to convert at least a portion of the ethyl groups to methyl groups attached to the benzene ring so that more valuable products such as xylenes can be made.

To maximize xylene production, the C9+ aromatics in the C6+ reconstituted oil stream can be separated and then fed to the transalkylation reactor along with benzene and/or toluene. In the presence of a transalkylation catalyst and under transalkylation conditions, C9+ aromatics and benzene/toluene exchange methyl groups to produce more xylenes. To convert C9+ aromatic hydrocarbons containing C2+ alkyl substituents and/or aliphatic rings to useful products (such as xylenes), the strategy is to dealkylate such C2+ alkyl substituents in the vapor phase in an efficient manner. The transalkylation is carried out in the presence of a catalyst. The removed alkyl groups form light hydrocarbons in the transalkylation reactor in the presence of hydrogen. Vapor phase transalkylation is energy intensive. It would be beneficial to convert at least a portion of the C2+ groups and aliphatic rings to methyl groups attached to the benzene ring so that more valuable products such as xylenes can be made.

C8 aromatics are also present in hydrotreated steam cracked naphtha ("SCN"). Traditionally, however, hydrotreated SCN streams have not been considered an economical raw material for the manufacture of xylene products due to the high concentrations of ethylbenzene and indene therein. It would be desirable to develop a process for producing xylene product from a hydrotreated SCN stream.

There is still a need for more energy efficient processes, such as C8 aromatics isomerization processes and C9+ aromatics transalkylation processes, to produce more xylenes from reconstituted oil streams and other similar sources of aromatics (such as hydrotreated SCN streams), especially is paraxylene. This disclosure meets this need and others.

It has been discovered that an alkyl-demethylation process can be used to selectively convert C2+-hydrocarbyl-substituted aromatics to produce alkyl-demethylated hydrocarbons (especially methylated aromatics), the C2+-hydrocarbyl-substituted aromatics An aliphatic ring comprising a C2+ alkyl group attached to an aromatic ring therein or fused to an aromatic ring therein. Incorporating an alkyl-demethylation process into an aromatics manufacturing process (such as a C8 aromatics isomerization process, especially a liquid phase isomerization process) can have at least one of the following advantages: (i) improved energy efficiency; ( ii) increased production (relative to benzene) of more valuable products such as xylene; (iii) improved carbon utilization (lower fuel gas generation, higher overall product yield); and (iv) improved process, Equipment and system simplification.

A first aspect of the present disclosure relates to a C8 aromatics isomerization process comprising one or more of the following: (i) providing a first C8 aromatics stream comprising ethylbenzene, para-xylene, meta-xylene, and optional ortho-xylene; (ii) separating the first C8 aromatics stream in a para-xylene recovery subsystem to obtain a para-xylene product stream and a para-xylene depletion stream; (iii) separating at least a portion of the para-xylene The toluene depleted stream is contacted with a first ethyl-demethylation catalyst in the first ethyl-demethylation zone to convert at least a portion of the ethylbenzene present in the paraxylene depleted stream to toluene to obtain the first ethyl-demethylation effluent leaving the first ethyl-demethylation zone; (iv) combining at least a portion of the first ethyl-demethylation effluent and optionally at least A portion of this para-xylene depleted stream is contacted with a first xylene isomerization catalyst in a first xylene isomerization zone under a first set of xylene isomerization conditions to obtain a first xylene isomerization and (v) supplying at least a portion of the first xylene isomerization effluent to the paraxylene recovery subsystem to obtain the paraxylene product stream and the paraxylene depletion stream.

A second aspect of the present disclosure relates to a method of converting C8 aromatics, the method comprising one or more of the following: (i) providing a first C8 aromatics stream comprising ethylbenzene, para-xylene, meta-xylene, and optionally ortho-xylene; (ii) separating the first C8 aromatics stream in a para-xylene recovery subsystem to obtain a para-xylene product stream and a para-xylene depletion stream; (iii) separating at least a portion of the para-xylene The depletion stream is contacted with a first ethyl-demethylation catalyst in a first ethyl-demethylation zone under a first set of alkyl-demethylation conditions to deplete the para-xylene present in the depletion. converting at least a portion of the ethylbenzene in the exhaust stream to toluene to obtain a first ethyl-demethylation effluent leaving the first ethyl-demethylation zone; (iv) converting at least a portion of the first ethylbenzene The ethyl-demethylation effluent and optionally at least a portion of this para-xylene depletion stream is isomerized in a first set of xylenes in a first xylene isomerization zone with a first xylene isomerization catalyst contacting under conditions to obtain a first xylene isomerization effluent; and (v) supplying at least a portion of the first xylene isomerization effluent to the para-xylene recovery subsystem to obtain the para-xylene A product stream and the para-xylene depletion stream; wherein at least one of the following is satisfied: (a) the first set of alkyl-demethylation conditions comprises: at a temperature in the range from 200 to 500°C; at a temperature from absolute pressure in the range from 350 to 2500 kPa; molar ratio of molecular hydrogen to hydrocarbon in the range from 0.5 to 20; and liquid weight hourly space velocity in the range from 1 to 20 h ^-1 ; and (b) the The first ethyl-demethylation catalyst comprises: a first metal element selected from Group 7, 8, 9, and 10 metals and combinations thereof, and a support.

Various embodiments, modifications, and examples of the present invention will now be described, including the preferred embodiments and definitions employed herein for the purpose of understanding the claimed invention. While the following detailed description gives specific preferred embodiments, those skilled in the art will understand that these embodiments are exemplary only and that the invention may be practiced in other ways. For the purpose of infringement identification, the scope of the present invention will refer to any one or more of the appended claims (including equivalents thereof), and elements or limitations equivalent thereto. Any reference to an "invention" may refer to one or more, but not necessarily all, inventions for which the scope of the claim is limited.

In this disclosure, methods are described as including at least one "step." It should be understood that each step is an act or operation that may be performed one or more times in the method in a continuous or discontinuous manner. Unless stated to the contrary or the context clearly dictates otherwise, various steps in a method may be performed sequentially in the order in which they are listed (with or without overlap with one or more other steps), or in any other order as appropriate. Furthermore, one or more or even all of the steps may be performed simultaneously on the same or different batches of material. For example, in a continuous process, when the first step of the process is performed on a feedstock that is just fed into the process at the beginning, the intermediate material formed by treating the feedstock fed into the process earlier in the first step may be At the same time, the second step is carried out. Preferably, the above steps are performed in the above order.

Unless otherwise indicated, all numbers in this disclosure expressing quantities are in all cases understood to be modified by the word "about." It should also be understood that the precise numerical values used in the specification and claimed scope constitute the specific embodiment. Efforts have been made to ensure the accuracy of the data in the examples. However, it should be understood that any measurement data inherently contains some level of error due to limitations of the techniques and equipment used for the measurement.

As used herein, the indefinite articles "a (a)" or "an (an)" mean "at least one" unless stated to the contrary or the context clearly dictates otherwise. Thus, embodiments using "a fractionation column" include embodiments using one, two, or more fractionation columns, unless stated to the contrary or the context clearly dictates that only one fractionation column is used.

As used herein, "consisting essentially of" means that a composition, feed, or effluent comprises at least 60% by weight, preferably at least 70% by weight, based on the total weight of the composition, feed, or effluent. % by weight, more preferably at least 80% by weight, more preferably at least 90% by weight, still more preferably at least 95% by weight of a given component at a concentration.

The term "hydrocarbon" refers to (i) any compound consisting of hydrogen and carbon atoms or (ii) any mixture of two or more such compounds in (i). The term "Cn hydrocarbon" (where n is a positive integer) refers to (i) any hydrocarbon compound containing a total of n carbon atoms in its molecule, or (ii) any of two or more such hydrocarbon compounds in (i) mixture. Thus, the C2 hydrocarbon can be ethane, ethylene, acetylene, or a mixture of at least two of them in any ratio. "Cm to Cn hydrocarbons" or "Cm-Cn hydrocarbons" (where m and n are positive integers and m<n) refers to Cm, Cm+1, Cm+2, ..., Cn-1, Cn hydrocarbons, or both or Any of any mixture of more. Thus, "C2 to C3 hydrocarbons" or "C2-C3 hydrocarbons" can be ethane, ethylene, acetylene, propane, propylene, propyne, propadiene, cyclopropane, or two or more of these components in between. any mixture in any proportion. A "saturated C2-C3 hydrocarbon" can be ethane, propane, cyclopropane, or any mixture of two or more thereof in any ratio. "Cn+hydrocarbon" means (i) any hydrocarbon compound containing in its molecule a total of at least n carbon atoms, or (ii) any mixture of two or more such hydrocarbon compounds in (i). "Cn-hydrocarbon" means (i) any hydrocarbon compound containing in its molecule a total of up to n carbon atoms, or (ii) any mixture of two or more such hydrocarbon compounds in (i). "Cm hydrocarbon stream" means a hydrocarbon stream consisting essentially of Cm hydrocarbons. "Cm-Cn hydrocarbon stream" means a hydrocarbon stream consisting essentially of Cm-Cn hydrocarbons.

In this disclosure "light hydrocarbon" refers to any C5-hydrocarbon.

"Liquid phase isomerization" refers to a process for the isomerization of C8 aromatics in the presence of an isomerization catalyst in an isomerization zone whereby xylene (e.g., para-xylene is depleted and/or depleted under isomerization conditions) or ortho-xylene depleted xylene mixture) isomerization such that the aromatics present in the isomerization zone are substantially liquid phase. "Substantially liquid phase" means ≥ 90 wt %, preferably ≥ 95 wt %, preferably ≥ 99 wt %, preferably the entire liquid phase. Such isomerization conditions are referred to as liquid phase isomerization conditions.

"Vapor phase isomerization" refers to a process for the isomerization of C8 aromatics in the presence of an isomerization catalyst in an isomerization zone whereby xylenes (e.g., para-xylene depletion and/or xylene) under isomerization conditions or ortho-xylene-depleted xylene mixture) is isomerized so that the aromatics present in the isomerization zone are in a substantially vapor phase. "Substantially vapor phase" means ≥ 90 wt %, preferably ≥ 95 wt %, preferably ≥ 99 wt %, preferably the entire vapor phase. Such isomerization conditions are referred to as vapor phase isomerization conditions.

"Liquid phase transalkylation" means in the transalkylation zone in the presence of a transalkylation catalyst between aromatics (e.g., between light aromatics such as benzene and/or toluene and heavy aromatics such as C9+ aromatics, or between two toluene molecules), whereby the aromatics exchange under transalkylation conditions for the substituents attached to the aromatic rings therein such that the Aromatic hydrocarbons are substantially liquid phase. "Substantially liquid phase" means ≥ 90 wt %, preferably ≥ 95 wt %, preferably ≥ 99 wt %, preferably the entire liquid phase. Such transalkylation conditions are referred to as liquid phase transalkylation conditions. Therefore, the toluene disproportionation process, which converts toluene to xylene and benzene, is a special type of transalkylation process.

"Vapor phase transalkylation" means in the transalkylation zone in the presence of a transalkylation catalyst between aromatics (e.g., between light aromatics such as benzene and/or toluene and heavy aromatics such as C9+ aromatics, or between two toluene molecules), whereby the aromatics exchange under transalkylation conditions for the substituents attached to the aromatic rings therein such that the Aromatic hydrocarbons are substantially in the vapor phase. "Substantially vapor phase" means ≥ 90 wt %, preferably ≥ 95 wt %, preferably ≥ 99 wt %, preferably the entire vapor phase. Such transalkylation conditions are referred to as vapor phase transalkylation conditions. Therefore, the toluene disproportionation process to convert toluene to xylene and benzene is a specific type of transalkylation process.

As used herein, "wt %" refers to weight percent, "vol %" refers to volume percent, "mol %" refers to molar percent, and "ppm" refers to Parts per million, and "ppm by weight (ppm wt)" and "wppm" are used interchangeably to refer to parts per million by weight. All concentrations herein are expressed as the total amount of the above-mentioned composition. All ranges expressed herein shall be inclusive of both endpoints as two specific embodiments unless stated or indicated to the contrary.

The nomenclature of elements and their groups used in this paper is based on the periodic table used by the International Union of Pure and Applied Chemistry after 1988. An example of a periodic table is shown on the inside front cover of Advanced Inorganic Chemistry, ^6th Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

"Methylated aromatic hydrocarbon" refers to an aromatic hydrocarbon that contains at least one methyl group and only the methyl group is attached to the aromatic ring in which it is attached. Examples of methylated aromatic hydrocarbons are: toluene, xylene, trimethyl, tetramethyl, pentamethyl, hexamethyl, methyl naphthalene, xylene, trimethyl naphthalene, tetramethyl naphthalene, and the like.

"C2+-hydrocarbyl-substituted aromatic hydrocarbons" refers to aromatic hydrocarbons comprising substituted aromatic rings other than methylated aromatic hydrocarbons. The C2+-hydrocarbyl-substituted aromatic hydrocarbon may comprise (i) a C2+-hydrocarbyl group (eg, a C2+-alkyl group) attached to an aromatic ring therein and/or (ii) an aliphatic ring fused to an aromatic ring therein . Examples of C2+-hydrocarbyl-substituted aromatic hydrocarbons in case (i) include, but are not limited to: ethylbenzene (C8), ethyltoluene (C9), n-propylbenzene (C9), cumene (C9), ethylxylene (C10), diethylbenzene (C10), n-propyl toluene (C10), cumene (that is, cumene) (C10), n-butylbenzene (C10), secondary butylbenzene (C10) , Tertiary butylbenzene (C10) and so on. Examples of C2+-hydrocarbyl-substituted aromatic hydrocarbons in the case of (ii) include, but are not limited to: dihydroindene (C9), indene (C9), methyldihydroindene (C10), methylindene (C10), tetrahydronaphthalene ( C10), methyltetrahydronaphthalene (C11), dimethyldihydroindene (C11), ethyldihydroindene (C11) and the like. Benzene and naphthalene are neither methylated aromatics nor C2+-hydrocarbyl-substituted aromatics.

(甲基二氫茚) 二氫茚、丙基甲苯、二乙苯、乙基甲苯、丁苯、正丙苯、異丙苯、乙苯、二甲苯、甲苯

(甲基二氫茚) 乙基甲苯、乙基二甲苯、三甲苯、丁基甲苯、丙基甲苯、二甲苯

(四氫萘) 丙基甲苯、二乙苯、丁苯、正丙苯、異丙苯、乙基甲苯、二甲苯、乙苯、甲苯 "Alkyl-demethylation" refers to the removal of (i) from a Cm (m ≥ 2) alkyl group attached to an aromatic ring in the presence of an alkyl-demethylation catalyst and molecular hydrogen an or multiple carbon atoms to leave Cm' residual alkyl attached to the aromatic ring, where 1≤m'≤m-1, preferably m'=1; or (ii) from fused to the aromatic ring The Cn aliphatic ring removes one or more carbon atoms to leave one or more residual alkyl groups (preferably methyl) containing a total of n' carbon atoms, where 1≤n'≤n-2. In this disclosure, reactions (i) and (ii) are collectively referred to as "alkyl-demethylation reactions". Thus, alkyl-demethylation of C2+-hydrocarbyl-substituted aromatic hydrocarbons containing Cm(m≧2) alkyl groups attached to the aromatic ring therein can result in Cm-1 alkyl, or Cm-2 alkanes Alkyl, ..., or methyl-substituted aromatic hydrocarbons become alkyl-demethylated hydrocarbons. Alkyl-demethylation of C2+-hydrocarbyl-substituted aromatic hydrocarbons comprising n-membered (n≥5) aliphatic rings of the aromatic ring fused to them can result in a total of n-2, n-3, n -4, ..., or an aromatic hydrocarbon substituted with at least one substituent (preferably two methyl groups) of 1 carbon atom. The removed methyl groups form light hydrocarbons (preferably methane) in the presence of molecular hydrogen. For C2+-hydrocarbyl-substituted aromatic hydrocarbons, alkyl-demethylation catalysts are desirable for the above-mentioned alkyl-demethylation due to (i) removal of all Cn attached to the aromatic ring ( n > 2) groups leave no residual substituents and (ii) removal of the methyl group attached to the aromatic ring leaves no residual substituents. Thus, further alkyl-demethylation of alkyl-demethylated hydrocarbons (also C2+-hydrocarbyl-substituted aromatics) can result in the formation of methylated aromatic hydrocarbons (eg, tetratoluene, mesitylene, xylene, and toluene) volume increase. Without intending to be bound by a particular theory, such methylated aromatic hydrocarbons can be prepared from C2+-hydrocarbyl arenes with or without the formation of alkyl-demethylated hydrocarbons as intermediate C2+-hydrocarbyl arenes. Ideally, treating an aromatic feed mixture comprising C2+-hydrocarbyl substituted aromatics by alkyl-demethylation produces an aromatic product mixture having a higher molar ratio of methyl to aromatic rings than the feed mixture. Examples of alkyl-demethylation reactions of C2+-hydrocarbyl-substituted aromatic hydrocarbons to obtain alkyl-demethylated hydrocarbons include, but are not limited to, the following: C2+-hydrocarbyl-substituted aromatic hydrocarbons Alkyl-Demethylated Hydrocarbons Ethylbenzene Toluene n-Propylbenzene Ethylbenzene, Toluene Cumene Ethylbenzene, Toluene ethyl toluene Xylene Dihydroindene Ethyltoluene, n-propylbenzene, cumene, ethylbenzene, xylene, toluene

(methyldihydroindene) Dihydroindene, propyltoluene, diethylbenzene, ethyltoluene, butylbenzene, n-propylbenzene, cumene, ethylbenzene, xylene, toluene

(methyldihydroindene) Ethyltoluene, ethylxylene, trimethylbenzene, butyltoluene, propyltoluene, xylene

(Tetralin) Propyltoluene, diethylbenzene, butylbenzene, n-propylbenzene, cumene, ethyltoluene, xylene, ethylbenzene, toluene

"Dealkylation" of an alkyl group attached to an aromatic ring refers to the removal of all alkyl groups without leaving residual groups attached to the aromatic ring. Thus, the methyl group will be demethylated in toluene to form benzene, the ethyl group will be deethylated in ethylbenzene to form benzene, the ethyl group will be deethylated in ethyltoluene to form toluene, and the Depropylation of isopropyl in cumene to form benzene is a specific form of dealkylation. Dealkylation of alkylated aromatics is typically accomplished in the presence of molecular hydrogen in the presence of a dealkylation catalyst selective for dealkylation during the above-described alkyl demethylation. The alkyl groups removed in the dealkylation reaction form light hydrocarbons in the presence of molecular hydrogen.

The effluent or feed is also sometimes referred to as a stream in this disclosure. Where two or more streams are shown to form a combined stream and then supplied to a tank, this should be construed to include the alternative of supplying the aforementioned streams separately to the tank where appropriate. Likewise, where two or more streams are supplied separately to the tank, it should be construed to include the alternative of mixing the aforementioned streams into a combined stream prior to entering the tank where appropriate. Alkyl-demethylation methods of the present disclosure

The alkyl-demethylation process occurs in the alkyl-demethylation zone under a set of alkyl-demethylation conditions in the presence of an alkyl-demethylation catalyst. Cm+(m≥2) alkyl groups attached to aromatic rings (eg, benzene rings, naphthalene rings, etc.) lose one or more terminal carbon atoms (i.e., from The alkyl group on the aromatic ring loses a carbon atom) to preferably form a methylated aromatic hydrocarbon with a methyl group attached to the aromatic ring. Preferably, the alkyl-demethylation ratio of alkyl-demethylation catalysts to Cm (m ≥ 2) alkyl groups attached to aromatic rings under alkyl-demethylation conditions Demethylation of the methyl group attached to the aromatic ring is more favorable. Thus, alkyl-demethylation (ie, ethyl-demethylation) of ethylbenzene results in a net production of toluene, which is not conducive to further demethylation to produce benzene. Alkyl-demethylation of ethyltoluene results in a net production of xylenes, which is not conducive to further demethylation to produce toluene and benzene. Similarly, alkyl-demethylation of C3-alkylbenzenes (ie, benzenes substituted with one C3-alkyl group) preferably yields toluene. Alkyl-demethylation of C3-alkyltoluenes preferably results in a net production of xylenes. Therefore, the alkyl-demethylation process is more favorable for the production of methylated aromatics (toluene, xylenes, mesitylene, etc.) than for the production of benzene. The process for converting aromatics of the present disclosure may advantageously comprise one or more alkyl-demethylation process steps.

Aromatics containing an aliphatic ring fused to an aromatic ring in the presence of an alkyl-demethylation catalyst and under alkyl-demethylation conditions (eg indene, methylindene, tetra hydronaphthalene, methyltetrahydronaphthalene, etc.) may undergo cleavage of the aliphatic ring to form one or more linear or branched residue groups attached to the aromatic ring (with or without prior loss from the aliphatic ring) one carbon atom). Any C2+ linear or branched residual alkyl groups can undergo one or more alkyl-demethylation reaction steps for eventual conversion to methyl groups attached to the aromatic ring, detrimental to further demethylation. Thus, C2+-hydrocarbyl-substituted aromatics (such as indene, methylindene, tetralin, and methyltetralin) can be converted to methylated aromatics in an alkyl-demethylation process. In the methods of the present disclosure including an alkyl-demethylation step in the alkyl-demethylation zone, preferably the alkyl-demethylation catalyst is capable of catalyzing the cleavage of fusion to the aromatic ring the aliphatic ring. In cases where the activity of the alkyl-demethylation catalyst is insufficient to catalyze the cleavage of the aliphatic ring, additional catalysts selective for the cleavage of the aliphatic ring may also be included in the alkyl-demethylation zone.

Although alkyl-demethylation reactions such as those described above are advantageous in the alkyl-demethylation processes of the present disclosure, it should be understood that certain side reactions other than alkyl-demethylation reactions are It is possible to some extent in the alkyl-demethylation zone under alkyl-demethylation reaction conditions in the presence of a demethylation catalyst.

The hydrocarbon feed to the alkyl-demethylation zone in the process of the present disclosure comprises C2+-hydrocarbyl substituted aromatic hydrocarbons. The concentration of C2+-hydrocarbyl substituted aromatics in the feed may range from c1 to c2 wt % based on the total weight of C6+ aromatics in the feed to the zone, where c1 and c2 may independently be, for example, 2, 4 , 5, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, as long as c1 < c2. Thus, depending on the source of the feed, feeds subjected to alkyl-demethylation may contain relatively low to very high concentrations of such C2+-hydrocarbyl-substituted aromatic hydrocarbons.

In certain embodiments, the hydrocarbon feed to the alkyl-demethylation zone may comprise C8 aromatics including ethylbenzene and various concentrations of xylenes. In certain embodiments, in the feed to the alkyl-demethylation zone (eg, the para-xylene depleted feed produced from the para-xylene separation subsystem in the process described below in relation to the scheme) The ethylbenzene concentration can be in the range of c(EB)1 to c(EB)2 wt % based on the total weight of C8 aromatics contained in the feed, wherein c(EB)1 and c(EB)2 can be independently Ground is, for example, 2, 4, 5, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, or 50, as long as c(EB)1 < c(EB)2. The methods of the present disclosure may be particularly advantageous for processing streams containing high concentrations of ethylbenzene, such as > 10 wt %, > 20 wt %, or ≥ 30% by weight. Toluene can be converted to additional amounts of xylenes ( especially p-xylene).

In certain embodiments, the hydrocarbon feed to the alkyl-demethylation zone may comprise C9+ aromatics including methylethylbenzene, C3-alkyl substituted benzene, dihydroindene, trimethylbenzene at various concentrations , C4-alkyl substituted benzene, methyldihydroindene, tetramethylbenzene, tetrahydronaphthalene, methyltetrahydronaphthalene and the like. In certain embodiments, C9+ in the feed to the alkyl-demethylation zone (eg, in the C9+ rich aromatics stream produced from the xylene separator as described in the following process in relation to the scheme) The C2+-hydrocarbyl-substituted aromatics concentration may be in the range of cx1 to cx2 wt % based on the total weight of C9+ aromatics contained in the feed, where cx1 and cx2 may independently be, for example, 10, 15, 20, 25, 30 , 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or 90, as long as cx1 < cx2. The methods of the present disclosure can be particularly advantageously used to process streams containing high concentrations of C9+C2+-hydrocarbyl substituted aromatics, such as ≥30 wt%, ≥40 wt%, based on the weight of all C8 aromatics in the feed, Or ≥40 wt%, ≥50 wt%, ≥60 wt%, ≥70 wt%, ≥80 wt%. A large number of C9+C2+-hydrocarbyl-substituted aromatics can be conveniently converted into useful methylated aromatics, such as toluene, xylene, and trimethylbenzene. Toluene can be converted to additional amounts of xylenes ( especially p-xylene). C9+ methylated aromatics (including tritoluene, tetratoluene, etc.) can be converted to additional amounts of xylenes (particularly para-xylene) by benzene addition and/or toluene transalkylation.

The alkyl-demethylation step is preferably carried out in the presence of molecular hydrogen co-fed to the alkyl-demethylation zone. The methyl groups removed in the alkyl-demethylation step are converted to light hydrocarbons (such as methane) in the presence of molecular hydrogen.

The methods of the present disclosure can include one or more alkyl-demethylation regions. The alkyl-demethylation zone can include a portion of the reactors, all of the reactors, or multiple reactors. Where multiple alkyl-demethylation regions are present in the methods of the present disclosure, the alkyl-demethylation catalyst and the conditions therein may be the same or different.

In the alkyl-demethylation zone, alkyl-demethylation conditions (eg, first, second, third, fourth, fifth, sixth, and seventh alkyl-demethylation conditions ) can vary widely depending on the composition of the feed undergoing alkyl-demethylation. Even within an alkyl-demethylation zone, the alkyl-demethylation conditions can vary widely within one production stage or from one production stage to another. Thus, alkyl-demethylation conditions may include temperatures ranging from t1 to t2°C, where t1 and t2 may independently be, for example, 200, 220, 240, 250, 260, 280, 300, 320, 340, 350, 360, 380, 400, 420, 440, 450, 460, 480, or 500, as long as t1 < t2. The alkyl-demethylation conditions may include absolute pressures in the alkyl-demethylation zone in the range from p1 to p2 kPa, where p1 and p2 may independently be, for example, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, or 2500, as long as p1 < p2. Thus, the alkyl-demethylation conditions can be such that the aromatics are in a substantially vapor phase, a substantially liquid phase, or a mixed phase in the alkyl-demethylation zone. Alkyl-demethylation conditions can include molar ratios of molecular hydrogen to hydrocarbons ranging from r1 to r2, where r1 and r2 can independently be, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, as long as r1 < r2. Alkyl-demethylation conditions may additionally include a liquid weight hourly space velocity ("WHSV") in the range from w1 to w2, where w1 and w2 may independently be, for example, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, or 20, as long as w1 < w2.

Specifically, for a C8 aromatics stream consisting essentially of or consisting essentially of xylenes and ethylbenzene (such as the paraxylene depleted stream produced by the paraxylene separation subsystem described below in relation to the scheme), alkanes Radical-demethylation conditions can include temperatures ranging from t3 to t4°C, where t3 and t4 can independently be, for example, 200, 220, 240, 250, 260, 280, 300, 320, 340, 350, 360 , 380, 400, 420, 440, 450, 460, 480, or 500, as long as t3 < t4. Alkyl-demethylation conditions can include absolute pressures in the alkyl-demethylation zone in the range from p3 to p4 kPa, where p3 and p4 can independently be, for example, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, or 2500, as long as p3 < p4. Thus, the alkyl-demethylation conditions can be such that the C8 aromatics are in a substantially vapor phase, a substantially liquid phase, or a mixed phase in the alkyl-demethylation zone. Alkyl-demethylation conditions can include molar ratios of molecular hydrogen to hydrocarbons ranging from r1 to r2, where r1 and r2 can independently be, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, as long as r1 < r2. Alkyl-demethylation conditions may additionally include a weight hourly space velocity ("WHSV") in the range from w1 to w2, where w1 and w2 may independently be, for example, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1 , 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, or 20, as long as w1 < w2.

Specifically, for a C9+ aromatics-rich stream containing or consisting essentially of C9+ aromatics (such as a C9+ aromatics-rich stream produced by the paraxylene separator described below in relation to the scheme), alkyl-demethylation The temperature conditions can include temperatures ranging from t5 to t6°C, wherein t5 and t6 can independently be, for example, 200, 220, 240, 250, 260, 280, 300, 320, 340, 350, 360, 380, 400, 420, 440, 450, 460, 480, or 500, as long as t5<t6. The alkyl-demethylation conditions can include absolute pressures in the alkyl-demethylation zone in the range from p5 to p6 kPa, where p5 and p6 can independently be, for example, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, or 2500, as long as p5 < p6. Thus, the alkyl-demethylation conditions can be such that the C8 aromatics are in a substantially vapor phase, a substantially liquid phase, or a mixed phase in the alkyl-demethylation zone. Alkyl-demethylation conditions may include molar ratios of molecular hydrogen to hydrocarbons ranging from r1 to r2, where r1 and r2 may independently be, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, as long as r1 < r2. Alkyl-demethylation conditions may additionally include a weight hourly space velocity ("WHSV") in the range from w1 to w2, where w1 and w2 may independently be, for example, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1 , 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, or 20, as long as w1 < w2. Alkyl-demethylation catalysts of the present disclosure

The alkyl-demethylation catalyst that can be used in the alkyl-demethylation zone in the methods of the present disclosure comprises a first metal element selected from the group consisting of Groups 7, 8, 9, and 10 metals and combinations thereof , an optional second metal element selected from Groups 11, 12, 13, and 14, and a support. Preferably, the first metal element is selected from Fe, Co, Ni, Ru, Rh, Re, Os, Ir, and combinations and mixtures thereof. The concentration of the first metal element may be in the range of c(m1)1 to c(m1)2 wt % based on the total weight of the alkyl-demethylation catalyst, wherein c(m1)1 and c(m1 )2 can be independently e.g. 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, as long as c(m1) 1<c(m1)2. Without intending to be bound by a particular theory, it is believed that the first metal element catalyzes the hydrogenolysis of the alkyl group attached to the aromatic ring to achieve the alkyl-demethylation. Preferably, the optional second metal system is selected from: Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations and mixtures thereof. The concentration of the second metal element may be in the range of c(m2)1 to c(m2)2 wt % based on the total weight of the alkyl-demethylation catalyst, wherein c(m2)1 and c(m2 )2 can be independently e.g. 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, as long as c(m2) 1<c(m2)2. Without intending to be bound by a particular theory, it is believed that the second metal element, when combined with the first metal element, can minimize undesired methylated aromatic demethylation and/or aromatic ring saturation and/or hydrocracking reactions , to achieve high selectivity for alkyl-demethylation.

The support in an alkyl-demethylation catalyst can be, for example, silica, alumina, kaolin, zirconia, any molecular sieve (eg, any zeolite), mixtures and compositions thereof. Preferred support materials are high surface area materials (≧100 m ² /g). Mild to moderate acidity is preferred to facilitate metal dispersion on the support while still allowing high selectivity for the desired demethylation reaction. Examples of supports that can be used include silica, alumina (preferably in the gamma and theta phases), low acidity zeolites, silica-alumina, lanthanides (eg La, Ce) and/or Group IVB metals ( For example, Zr) modified alumina. Additives such as alkalis and/or alkaline earth metals and/or chlorides can be used to adjust the acidity of the support to a desired level. The acidity of the support can be increased where a combination of transalkylation/isomerization and demethylation chemistry is desired. The amount of support in the alkyl-demethylation catalyst can range from c(s)1 to c(s)2 wt %, where c(s)1 and c(s2)2 can independently be, for example, 2, 4, 5, 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or 99, as long as c(s)1<c(s)2.

The alkyl-demethylation catalyst may additionally comprise an optional promoter selected from Group 1 and 2 metal elements, and compositions and mixtures thereof. The amount of accelerator may be in the range of c(p)1 to c(p)2 wt % based on the total weight of the alkyl-demethylation catalyst, wherein c(p)1 and c(p)2 may independently be, for example, 0.01, 0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, as long as c(p)1< c(p)2. Preferably, the optional promoter metal is selected from: Li, Na, K, Cs, Mg, Ca, Ba. Groups 1 and 2 promoters can enhance the performance of alkyl-demethylation catalysts, especially with respect to activity and para-alkyl-demethylation, when used in combination with a first metal element and an optional second metal element. of selectivity.

Any method known in the art of making supported metal catalysts can be used to make the alkyl-demethylation catalysts of the present disclosure. In one exemplary method, a solution (eg, an aqueous solution) of an elemental metal precursor compound and an accelerator precursor material may be infiltrated into the support, followed by drying and calcination to obtain a support containing the elemental metal, and optional accelerator The alkyl-demethylation catalyst. Alternatively, the support precursor material, the metallic elemental precursor material, and the optional promoter precursor material can be mixed to form a blend, which is then dried and calcined to obtain the alkyl-demethylation compound. media.

Prior to the use of an alkyl-demethylation catalyst in an alkyl-demethylation process, it is preferred to either ex-situ (i.e. outside the intended use of the alkyl-demethylation zone) or in-situ (i.e. inside the alkyl-demethylation region of the intended use) to activate the catalyst. Activation can include, for example, heating the catalyst in the presence of, for example, a gas stream containing molecular hydrogen. C8 Aromatic Isomerization Process of the Present Disclosure

In a process for the manufacture of para-xylene in an aromatics manufacturing plant, a C8 aromatics mixture comprising meta-xylene, ortho-xylene, and ethylbenzene in addition to para-xylene is typically separated in a para-xylene separation sub-system paraxylene. Depending on the composition of the C8 aromatic mixture (especially the paraxylene concentration in it), various techniques can be used to separate the paraxylene product, such as crystallization-based techniques and adsorption chromatography-based techniques . In separating the paraxylene product, a residual paraxylene depletion stream (referred to as raffinate in adsorption chromatography-based methods and filtrate in crystallization-based techniques, referred to herein as collectively referred to as the "raffinate"). The raffinate is rich in meta-xylene, ortho-xylene and ethylbenzene. To make more para-xylene, the raffinate is typically isomerized later in an isomerization zone operating under isomerization conditions in the presence of an isomerization catalyst. A portion of the isomerization effluent that is richer in paraxylene than the paraxylene depleted stream fed to the isomerization zone may be recycled to the paraxylene separation and recovery subsystem to form a xylene loop. In the isomerization zone, the direct conversion of ethylbenzene to xylenes (particularly para-xylene) is difficult. Therefore, unless converted to other hydrocarbons and/or conducted away, ethylbenzene will accumulate in the xylene loop. Typically, in prior art processes, the isomerization catalyst and isomerization conditions are selected such that at least a portion of the ethylbenzene in the para-xylene depleted stream fed to the isomerization zone undergoes removal in the presence of molecular hydrogen. Alkylation (ie, deethylation), thereby producing benzene and light hydrocarbons. To facilitate deethylation, isomerization conditions are typically selected such that the C8 aromatics present in the isomerization zone are in a substantially vapor phase. In various prior art process versions, the isomerization catalyst and isomerization conditions were selected such that at least a portion of the ethylbenzene in the para-xylene depleted stream fed to the isomerization zone was converted to xylenes. To facilitate the conversion of ethylbenzene to xylenes, the isomerization conditions are typically selected such that the C8 aromatics present in the isomerization zone are in a substantially vapor phase. Although this disclosure focuses on the use of alkyl-demethylation with the prior art method of converting ethylbenzene to benzene, it should be noted that alkyl-demethylation can be applied with either version of the prior art method.

In the C8 aromatics isomerization process of the present disclosure, at least a portion of the para-xylene depleted stream is subjected to ethyl-substituted benzene (ie, ethyl-substituted benzene) under ethyl-demethylation conditions in the ethyl-demethylation zone. ethyl-demethylation of ethylbenzene) to convert a portion of the ethylbenzene to toluene. The ethyl-demethylation zone can be upstream of the isomerization zone, or partially or completely overlapping the isomerization zone. When the ethyl-demethylation region and the isomerization region overlap, both the isomerization catalyst and the ethyl-demethylation region can exist in the common region. Alternatively, in the overlapping region, one catalyst composition can exhibit the dual function of isomerization and ethyl-demethylation.

Since one or more ethyl-demethylation zones are present in the xylene loop, compared to prior art processes in which no ethyl-demethylation zones are present in the xylene loop, the ethyl acetate entering the isomerization can be The amount of benzene decreased. The reduced amount of ethylbenzene reduces the need to reduce ethylbenzene through deethylation. Thus, the need for vapor phase isomerization of the paraxylene depleted feed can be reduced. In certain embodiments, substantially all of the ethyl-demethylation effluent can be supplied to the liquid phase isomerization zone, wherein the isomerization of xylenes is performed at temperatures significantly lower than typical vapor phase isomerization processes happen below. Liquid phase isomerization is less energy intensive than vapor phase isomerization and is therefore preferred. Transalkylation Methods of the Present Disclosure

One aspect of the present disclosure pertains to a transalkylation process comprising: (A) providing a C9+ aromatics-rich stream comprising C2+-hydrocarbyl-substituted aromatics, wherein the C2+-hydrocarbyl-substituted aromatics have (i) attached to a C2+ alkyl substituent of an aromatic ring therein and/or (ii) an aliphatic ring fused to an aromatic ring therein; (B) combining at least a portion of the C9+ rich aromatic hydrocarbon stream with the first alkyl- The demethylation catalyst is optionally contacted in the first alkyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl groups contained in the C9+-rich aromatics stream The substituted aromatics are converted to alkyl-demethylated hydrocarbons to produce a first alkyl-demethylation effluent leaving the first alkyl-demethylation zone; (C) in a first separation unit the The C9+ aromatics-rich stream and/or the first alkyl-demethylation effluent are optionally separated to obtain a C9 to C10-rich aromatics stream and a C11+ aromatics-rich stream; (D) demethylating at least a portion of the first alkyl-demethylation The alkylation effluent and/or at least a portion of the C9 to C10 rich aromatics stream is combined with a second alkyl-demethylation catalyst in a second alkyl-demethylation zone in a second set of alkyl-demethylation optionally contacted under chemical conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if contained in the first alkyl-demethylation effluent and/or C9 to C10-rich aromatics stream) into alkyl-demethylation effluents. Methylated hydrocarbons to produce a second alkyl-demethylation effluent leaving the second alkyl-demethylation zone; (E) converting at least a portion of the C9+ rich aromatics stream, and/or at least a portion of the first The monoalkyl-demethylation effluent, and/or at least a portion of the C9 to C10-rich aromatics stream, and/or at least a portion of the second alkyl-demethylation effluent, is fed with the benzene/toluene stream to Transalkylation zone; (F) contacting C9+ aromatics with benzene/toluene in the presence of a transalkylation catalyst under transalkylation conditions in the transalkylation zone to produce a and (G) separating the transalkylation effluent in a second separation unit to obtain a random benzene product stream, a toluene-rich stream, and a C8+ aromatics-rich stream; wherein steps (B) and ( At least one of D) is performed.

In certain embodiments, the transalkylation process may additionally comprise: (H) separating at least a portion of the C8+ aromatics-rich stream in a third separation unit to obtain a xylene-rich stream and a C9+ aromatics-rich stream; and (I) ) provides at least a portion of the C9+ aromatics stream as at least a portion of the C9+ aromatics stream in step (A). Additionally and alternatively, the C9+ aromatics stream in step (A) can be obtained from separating the C8+ aromatics stream in a xylene separator, which in turn can be produced from a reformed oil separator that receives the C6+ hydrocarbon stream from the reformer. Of course, the third separation unit in step (A) may be a xylene separator that accepts two sources of C8+ aromatics.

In certain embodiments, the C9+ aromatics stream may be subjected to alkyl-demethylation in optional step (B). If this step is carried out, in the first alkyl-demethylation zone, aromatic hydrocarbons containing a part of C11+C2+-hydrocarbyl group substitution can be converted into tetratoluene, trimethylbenzene and xylene through alkyl-demethylation , toluene, and C8+C2+-hydrocarbyl-substituted aromatic hydrocarbons, and alkyl-demethylation can be used, for example, in the subsequent optional alkyl-demethylation step (D) and transalkylation step (F) to produce additional valuable and useful products such as xylenes and benzene, regardless of whether or not optional isolation step (C) is performed.

Step (C) is optional. If step (C) is performed with or without step (B), the C11+C2+-hydrocarbyl substituted aromatics present in the C9+ aromatics-rich stream will separate primarily into a C11+ aromatics-rich stream. If step (C) is performed as well as step (B), then as discussed above, the C11+C2+-hydrocarbyl-substituted aromatics present in the C9+ aromatics stream are at least partially converted to methyl-rich C10-aromatics, which can be used with for the manufacture of other valuable and useful products. In embodiments where steps (B) and (C) are carried out, it is required that the C9 to C10 rich hydrocarbon stream produced in step (C) also contains at least a portion (preferably all) of the C9 to C10 hydrocarbon stream produced in step (C) ) in the first alkyl-demethylation zone, especially if the C9+ aromatics-rich stream contains a high proportion of C11+C2+-hydrocarbyl-substituted aromatics. Although the C8-aromatics produced in step (B) may be separated into one or more additional streams from the first separation unit in step (C), they may be further separated to produce one or more benzene-rich stream, toluene-rich stream, and/or C8 aromatics-rich stream from which additional xylene product can be produced.

Step (D) is optional. If optional step (D) is carried out, the C2+-hydrocarbyl-substituted aromatic hydrocarbons contained in the feed to the second alkyl-demethylation zone are at least partially converted to produce alkyl-demethylated hydrocarbons, Its entirety contains more methyl groups attached to the aromatic ring than the C2+-hydrocarbyl-substituted aromatics supplied to the second alkyl-demethylation zone.

In the transalkylation method of the present disclosure, at least one of steps (B) and (D) is performed.

With and without steps (C) and (D), the first alkyl-demethylation effluent leaving the alkyl-demethylation zone will be partially or fully (preferably to the transalkylation zone in step (E). In this case, the feed from the first alkyl-demethylation zone to the transalkylation zone may comprise a portion of the unconverted C9+ aromatics supplied to the first alkyl-demethylation zone and C8-aromatic hydrocarbons produced in the first alkyl-demethylation zone.

In the absence of step (B) and steps (C) and (D) being performed, preferably at least a portion of the hydrocarbon feed (preferably the entire hydrocarbon feed) of the second alkyl-demethylation zone is At least a portion, preferably all, of the C9 to C10 rich aromatics stream produced in step (C). In the case where the hydrocarbon feed to the second alkyl-demethylation zone is entirely derived from the C9 to C10 rich aromatics stream produced in step (C), the presence of the second alkyl-demethylation zone in step (C) is present in the supply to the first Most of the C11+ aromatics in the C9+ aromatics-rich stream of a separation unit are not used to make xylenes in the transalkylation step.

With all steps (B), (C), and (D) carried out, a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbons supplied to the second alkyl-demethylation zone is further supplied by alkyl-demethylation Converted to produce additional methylated hydrocarbons in the second alkyl-demethylation effluent. Preferably, the feed to the second alkyl-demethylation zone comprises at least a portion (preferably all) of the C9 to C10 rich aromatics stream produced in step (C). Preferably, the entire feed to the second alkyl-demethylation zone comprises at least a portion (preferably all) of the C9 to C10 rich aromatics stream. C2+-hydrocarbyl-substituted aromatic hydrocarbons (which include e.g. ethylbenzene, C3-alkylbenzene, ethyltoluene) contained in the C9 to C10 rich hydrocarbon stream supplied to the second alkyl-demethylation zone in step (D) , dihydroindene, ethylxylene, diethylbenzene, methyldihydroindene, tetrahydronaphthalene, and one or more of C4-alkylbenzenes) can be passed through one or more alkyl-demethylation steps At least partially converted into toluene, xylene, trimethylbenzene. Carrying out steps (B) and (D) can result in methylated aromatics (including toluene) in the second alkyl-demethylation effluent supplied to the second alkyl-demethylation zone to the transalkylation zone , xylenes, trimethylbenzenes, and tetratoluenes), which can be advantageously and conveniently converted to xylenes in the transalkylation zone, are significantly increased.

In certain embodiments, the second alkyl-demethylation zone can be located upstream of the transalkylation zone. In this case, at least a portion (ideally all) of the second alkyl-demethylation effluent is supplied to the transalkylation zone. In one embodiment, the alkyl-demethylation zone and the transalkylation zone are located in separate tanks. In another embodiment, the alkyl-demethylation zone and the transalkylation zone may be located in a common tank (such as a reactor tank) with the alkyl-demethylation catalyst disposed in the upstream bed , and the transalkylation catalyst is configured in the downstream bed.

In certain embodiments, the second alkyl-demethylation zone can at least partially overlap the transalkylation zone. Thus, the two zones may exist in a common tank, such as a reactor tank. In the overlap of the two regions, both the transalkylation catalyst and the alkyl-demethylation catalyst may be present, for example, as a mixture of physical states. In another embodiment, the transalkylation catalyst exhibits the dual function of catalyzing the transalkylation and alkyl-demethylation reactions of non-alkyl-demethylated substituted aromatics.

In embodiments where a second alkyl-demethylation zone exists and is located upstream of the transalkylation zone, the process may additionally comprise subjecting at least a portion of the second alkyl-demethylation effluent and/or at least a A portion of the C9 to C10 rich aromatics stream is contacted with a third alkyl-demethylation catalyst in a third alkyl-demethylation zone under a third set of alkyl-demethylation conditions to convert at least a portion of the Conversion of C2+-hydrocarbyl-substituted aromatics (if contained in the second alkyl-demethylation effluent and/or C9 to C10-rich aromatics stream) to alkyl-demethylated aromatics, where the third alkyl - the demethylation zone at least partially overlaps the transalkylation zone. The third alkyl-demethylation zone can be considered equivalent to the second alkyl-demethylation zone at least partially overlapping the transalkylation zone, as described above.

The first, second, and third alkyl-demethylation catalysts can be the same or different. Any of the alkyl-demethylation catalysts previously described in the present disclosure can be used as one of the first, second, and third alkyl-demethylation catalysts in the transalkylation process of the present disclosure. or more.

The first, second, and third sets of alkyl-demethylation conditions may be the same or different in the first, second, and third alkyl-demethylation zones. These can include alkyl-demethylation temperatures ranging from t5 to t6°C, where t5 and t6 can independently be, for example, 200, 220, 240, 250, 260, 280, 300, 320, 340, 350 , 360, 380, 400, 420, 440, 450, 460, 480, or 500, as long as t5<t6. The alkyl-demethylation conditions can include absolute pressures in the alkyl-demethylation zone in the range from p5 to p6 kPa, where p5 and p6 can independently be, for example, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3200, 3400 or 3500, as long as p5 <p6.

Depending on the amount of toluene present in the second alkyl-demethylation effluent supplied to the transalkylation zone, additional amounts of benzene/toluene in the benzene/toluene stream may also be added in step (E). Toluene is supplied to the transalkylation zone. If additional benzene/toluene is supplied to the alkylation zone, the benzene/toluene stream may contain any ratio of benzene to toluene. Preferably, the benzene/toluene stream comprises ≥ 50 wt %, ≥ 60 wt %, ≥ 70 wt %, ≥ 80 wt %, ≥ 90 wt %, based on the total weight of benzene and toluene in the benzene/toluene stream, > 95 wt %, > 98 wt %, or > 99 wt % toluene. The appropriate ratio of toluene to C9+ aromatics in the hydrocarbon feed to the transalkylation zone can be determined based on the composition of the C9+ aromatics to maximize xylene production. In certain embodiments, at least a portion of the benzene product stream and/or at least a portion of the toluene-rich stream produced in step (G) is supplied to a transalkylation zone as at least a portion of the benzene in step (E) /toluene stream.

The transalkylation zone includes a transalkylation catalyst disposed therein. Transalkylation catalysts known in the art can be used in the transalkylation zone in the methods of the present disclosure. The transalkylation catalyst may comprise one or more zeolites, such as MFI, MEL, MTW, MOR, BEA, MEI, MWW framework zeolites. The transalkylation catalyst may additionally comprise a first metal element selected from the group 6, 7, 8, 9, and 10 metals, preferably Mo, Ru, Rh, Ru, Pd, Re, Os, Ir, Pt , a composition or mixture of two or more thereof. The transalkylation catalyst may additionally comprise a second metal element selected from Groups 11, 12, 13, and 14 metals, preferably Ag, Cu, Zn, Ga, In, Sn, or a combination of two or more thereof substance or mixture. The transalkylation catalyst may additionally contain binders such as alumina, silica, zirconia, titania, and combinations and mixtures thereof. For the transalkylation catalyst used in the methods of the present disclosure, the concentration of the first metal element can be desirably low, eg, in the range of c1 to c2 wt % based on the total weight of the transalkylation catalyst , where c1 and c2 can be 0.001, 0.004, 0.005, 0.008, 0.01, 0.04, 0.05, 0.08, 0.1, 0.4, 0.5, 1, as long as c1<c2. Furthermore, for the transalkylation catalyst used in the method of the present disclosure, the concentration of the second metal element can be desirably low, eg, c1 to c2 wt % based on the total weight of the transalkylation catalyst range, wherein c1 and c2 can be 0.001, 0.004, 0.005, 0.008, 0.01, 0.04, 0.05, 0.08, 0.1, 0.4, 0.5, 1, 2, 3, 4, 5, as long as c1<c2. In a particularly advantageous embodiment, the transalkylation catalyst is substantially free of Group 8, 9, or 10 metal elements.

The transalkylation conditions in the transalkylation zone can achieve vapor phase transalkylation, eg, where all aromatics present in the transalkylation zone are in the vapor phase. The transalkylation conditions can achieve liquid phase transalkylation, eg, where all aromatics present in the transalkylation zone are in the liquid phase. The transalkylation conditions allow for mixed-phase transalkylation in which the liquid and vapor phases of aromatics coexist in the transalkylation zone. Molecular hydrogen can be co-fed to the transalkylation zone.

In prior art transalkylation processes, in order to convert C2+-hydrocarbyl substituted aromatics to more valuable products in the transalkylation zone, typically the transalkylation catalyst and conditions are selected such that at least a portion of The C2+ alkyl groups attached to the aromatic ring all undergo dealkylation without leaving residual alkyl groups attached to the aromatic ring. To facilitate dealkylation of C2+ alkyl groups, typically up-transalkylation catalysts include noble metals, and typically high transalkylation temperatures that enable vapor-phase transalkylation are used. Hydrogenation of dealkylated C2+ alkyl groups requires the presence of molecular hydrogen fed to the transalkylation zone in order to avoid realkylation reactions. Vapor phase transalkylation requires heating of the hydrocarbon feed to high temperature followed by cooling and condensation of the transalkylation effluent for distillative separation and is therefore energy intensive. In addition, the C2+ alkyl groups and aliphatic rings fused to the aromatic rings in the C2+-hydrocarbyl substituted aromatic hydrocarbons supplied to the transalkylation zone are typically converted to low value light hydrocarbons in the presence of molecular hydrogen.

Due to the presence of one or more of the first, second, and third transalkylation zones and the performance of at least one of the alkyl-demethylation steps in the transalkylation process of the present disclosure, and fundamentally Compared to prior art transalkylation processes without an alkyl-demethylation step, the concentration of C2+ alkyl substituted aromatics supplied to the transalkylation zone can be significantly reduced. Thus, the need for dealkylation in the transalkylation zone of C2+ alkyl groups and aliphatic rings can be significantly reduced. Therefore, the transalkylation catalyst of the transalkylation method of the present disclosure can be free of metal elements (especially expensive precious metal elements), thereby reducing the cost. The reduced need for dealkylation enables liquid phase transalkylation to be achieved at significantly lower temperatures than required by vapor phase transalkylation processes, resulting in substantial energy savings and substantial improvements in energy efficiency. Reduced Need for Dealkylation Vapor, liquid, or mixed phase transalkylation can be accomplished without co-feeding molecular hydrogen, further simplifying the process, system, and equipment. In addition, C2+ alkyl groups and aliphatic rings are partially converted to residual methyl groups attached to aromatic rings, which can be used to make additional quantities of useful products such as xylenes.

The present disclosure is described in more detail below with reference to the accompanying drawings. Figure 1: Prior Art Approach

Figure 1 illustrates a prior art process 101 for the production of xylenes, particularly para-xylene products, from a reconstituted oil stream. In Figure 1, a heavy petroleum naphtha stream 103 (which has a normal boiling point in the range of, for example, 100 to 240°C, such as 120 to 220°C, or 140 to 200°C, or 140 to 180°C) will be produced by a crude oil refining process. supplied to the reorganization zone 105 . The heavy petroleum naphtha stream 103 may contain large amounts of paraffins and naphthenes, and small amounts of aromatics. The reformation zone 105 may comprise one or more of any conventional naphtha catalyst reformation reactor known in the art (eg, a fixed bed reactor for semi-regenerative processes or a moving bed reactor for continuous regeneration processes). The recombination catalyst is arranged in the recombination zone. The hydrocarbons in the heavy petroleum naphtha stream 103 undergo a series of chemical reactions (including, but not limited to, isomerization, aromatization, dehydrocyclization, etc.) when contacted with the recombination catalyst under recombination conditions (such as those well known in the art) , thereby converting at least a portion of the paraffins and naphthenes into aromatic hydrocarbons. It is known that in a typical recombination operation, various amounts (sometimes large) of C2+-hydrocarbyl-substituted aromatic hydrocarbons can be produced, that is, containing (i) C2+ alkyl groups bound to an aromatic ring therein and/or (ii) Aromatic hydrocarbons fused to aliphatic rings of aromatic rings therein. A reformed effluent 107 can be obtained from the reformation zone, which comprises C6+ aromatics (including benzene, toluene, xylenes, ethylbenzene, and C9+ aromatics) including C2+-hydrocarbyl substituted aromatics. In addition to aromatic hydrocarbons, the reformed effluent 107 may also contain non-aromatic hydrocarbons, such as alkanes and naphthenes. Preferably, the reformed effluent 107 consists essentially of C6+ aromatics. The reconstituted effluent 107 is referred to interchangeably herein as the reconstituted oil stream. Additional streams may also be produced from the reforming zone, such as a hydrogen stream (not shown) and a waste gas stream (not shown) comprising light hydrocarbons (eg, C5-hydrocarbons).

As shown in Figure 1, the reformed effluent 107, or a portion thereof, is then supplied to a reformed oil separator 109 (eg, a single distillation column, or a series of distillation columns), producing a C6 to C7 rich hydrocarbon stream 111 and a C8+ aromatics rich stream 113. The C6 to C7 rich hydrocarbon stream 111 contains benzene, toluene, paraffins and naphthenes azeotrope therewith, and the like. The C8+ aromatics-rich stream 113 may comprise C8 aromatics (eg, xylene and ethylbenzene), C9 aromatics (eg, trimethylbenzene, ethyltoluene, n-propylbenzene, cumene, and indene), C10 aromatics (eg, tetratoluene, Diethylbenzene, ethylxylene, methyl-n-propylbenzene, methyl cumene, n-butylbenzene, isobutylbenzene, secondary butylbenzene, tertiary butylbenzene, methyldihydroindene, tetrahydronaphthalene, and naphthalene), and even C11+ aromatics (eg methylnaphthalene, methyltetrahydronaphthalene). The C8+ aromatics-rich stream 113 is then optionally combined with other C8+ aromatics-rich streams such as stream 145 (described below) into a combined stream 114 that is supplied to a xylene separator 115 (eg, one or more distillation columns) to produce a xylene-rich stream 117 with C9+ aromatics stream 129.

Compared to stream 107, combined stream 114 is rich in C8+ aromatics and depleted in benzene, toluene, and azeotropes thereof. Preferably, stream 114 comprises benzene and toluene in a total concentration of &lt; 5 wt%, based on their total weight, such as &lt; Xylene-rich stream 117 contains xylenes and ethylbenzene. The ethylbenzene concentration in stream 117 may be in the range of c(EB)1 to c(EB)2 wt % based on the total weight of C8 aromatics contained in stream 117, wherein c(EB)1 and c(EB) 2 can independently be e.g. 38, 40, 42, 44, 45, 46, 48, or 50, as long as c(EB)1 < c(EB)2. In some cases, ethylbenzene concentrations can be so significant that c(EB)1≥10, c(EB)1≥15, c(EB)1≥20, c(EB)1≥25, or c(EB)1≥25 )1≥30. Stream 117 may contain various concentrations of para-xylene, depending on the composition of the C8+ aromatics-rich stream supplied to xylene separator 115. For example, stream 117 may comprise paraxylene at a concentration of c(pX)1 to c(pX)2 wt % based on the total weight of C8 aromatics contained in stream 117, where c(pX)1 and c(pX) 2 can independently be e.g. 54, 55, 56, 58, 60, as long as c(pX)1<c(pX)2.

As shown in FIG. 1 , to produce a para-xylene product, typically a para-xylene-rich stream 117 is supplied to a first para-xylene recovery sub-system 119 to produce a para-xylene-rich product stream 121 and para-xylene Stream 123 is exhausted. The first paraxylene recovery sub-system 119 can be any paraxylene separation system known in the art based on crystallization or based on adsorption chromatography. Typically a first para-xylene depleted stream 123, which is relatively rich in meta-xylene, ortho-xylene, and ethylbenzene from stream 117, is at least partially supplied to isomerization zone 125, which contains disposed therein and in isomerization zone 125. Isomerization catalyst that operates under chemical conditions. A portion of the meta- and ortho-xylenes in stream 125 supplied to isomerization zone 125 are converted to para-xylene when contacted with the isomerization catalyst under isomerization conditions. Isomerization effluent 127 exiting isomerization zone 125 contains a higher concentration of para-xylene than para-xylene depletion stream 123 . The isomerization effluent 127, or a portion thereof, is then supplied to the xylene separator 115. Xylene separator 115, para-xylene recovery subsystem 119, and isomerization zone 125 form a xylene loop.

In the process of FIG. 1, streams 113, 145, 114, 117, and 123 may contain significant concentrations of ethylbenzene (eg, > 5 wt %, > 10 wt %, > 15 wt % based on the total weight of C8 aromatics contained therein % by weight, >=20% by weight, >=25% by weight, >=30% by weight). If isomerization zone 125 does not have sufficient capacity to convert ethylbenzene, ethylbenzene will accumulate in the xylene loop over time, which is undesirable. To prevent the accumulation of ethylbenzene in the xylene loop, the isomerization catalyst and isomerization conditions are typically selected in zone 125 such that at least a portion of the ethylbenzene is converted to benzene by deethylation. To effect deethylation, isomerization conditions typically include temperatures and pressures sufficient to maintain the C8 aromatics in a substantially vapor phase in the isomerization zone ("vapor phase conditions", "vapor phase isomerization"). Performing the substantial vapor phase isomerization of xylenes requires heating the hydrocarbons to high temperature in the isomerization zone, followed by cooling and condensation of the isomerization effluent to a liquid state for distillative separation, and is therefore energy intensive. Additionally, due to aromatic ring saturation and/or ring breakage, vapor phase isomerization typically produces light and non-aromatic hydrocarbons resulting from dealkylation, which are typically fed to xylene separation in isomerization effluent 127 115 was previously removed in an intermediate deheptanizer (not shown), further complicating the xylene loop in the process.

C8 aromatics isomerization processes, catalysts, and conditions are disclosed, for example, in US Pat. Nos. 7,247,762 and 7,271,118, which are hereby incorporated by reference in their entirety.

As shown in FIG. 1 , C9+ aromatics stream 129 (typically containing C9, C10, and C11+ aromatics) produced by xylene separator 115 is then typically separated in distillation column 131 to obtain C9 to C10 rich aromatics stream 133 with C11+ aromatics stream 135 rich. Stream 135 is typically conducted away as, for example, a motor gasoline blend, fuel oil, and the like. Stream 133 contains methylated aromatics and C2+-hydrocarbyl substituted aromatics. The total concentration of C2+-hydrocarbyl-substituted aromatics in stream 133 can be significant, for example in the range of c(A1)1 to c(A1)2 wt % based on the total weight of aromatics in stream 133, where c( A1)1 and c(A1)2 can independently be, for example, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, or 40, as long as c(A1)1<c(A1)2. Stream 133, along with benzene/toluene rich stream 146, is then supplied to transalkylation zone 147 having a transalkylation catalyst disposed therein. C9 to C10 aromatics are reacted with benzene/toluene in the presence of a transalkylation catalyst and under transalkylation conditions to produce xylenes. Direct transalkylation between such C9 to C10 C2+-hydrocarbyl substituted aromatics and benzene/toluene yields ethylbenzene and other C9+C2+-hydrocarbyl substituted aromatics. In order to increase the production of xylene and/or benzene/toluene in transalkylation zone 147, typical upper transalkylation catalysts and transalkylation conditions are selected such that aromatics from C2+ alkyl groups are removed by dealkylation The complete conversion of the family rings yields at least a portion of the C9+C2+-hydrocarbyl substituted aromatics and ethylbenzene in the transalkylation zone (without removing the methyl groups attached directly to the aromatic rings). Dealkylation results in the conversion of C2+ alkyl groups to light hydrocarbons (typically in the presence of molecular hydrogen and the hydrogenation function of the dealkylation catalyst used in the transalkylation zone). Therefore, it is a loss to remove the C2+ alkyl groups in order to make xylenes. The C2+ alkyl group is preferably converted to a methyl group attached to the benzene ring - which can then be used to make xylenes via, for example, isomerization, transalkylation, and/or disproportionation. Similar to the deethylation of ethylbenzene, efficient dealkylation of C9 to C10 C2+-hydrocarbyl substituted aromatics with ethylbenzene in the transalkylation zone typically requires vapor phase conditions that require high temperatures. Because streams 146 and 133 must be heated to high temperatures to effect vapor phase isomerization prior to entering the transalkylation zone, subsequent cooling and condensation of the vapor effluent 149 from the transalkylation zone to a liquid phase for distillative separation, Therefore, such vapor-phase transalkylation is energy-intensive. Additionally, due to aromatic ring saturation and/or ring rupture, vapor phase transalkylation typically produces light and non-aromatic hydrocarbons resulting from dealkylation, which are typically supplied to the benzene column in isomerization effluent 127 141 was previously removed in an intermediate deheptanizer (not shown), further complicating the transalkylation process.

Aromatic transalkylation methods, catalysts, and conditions are disclosed, for example, in US Pat. Nos. 5,763,720 and 8,183,424, which are incorporated herein in their entirety.

As shown in FIG. 1 , C6 to C7 rich hydrocarbon stream 111 is typically supplied to extractive distillation zone 137 where C6 to C7 aromatics rich stream 139 and aromatics depleted raffinate stream 138 are produced. Stream 139 is then supplied to benzene column 141 to produce benzene product stream 143, toluene-rich stream 146, and C8+ aromatics-rich stream 145. Toluene-rich stream 146, or a portion thereof, is supplied to transalkylation zone 147 along with C9 to C10 aromatics-rich stream 133, as described above. C8+ aromatics-rich stream 145 is then fed to xylene separator 115 along with stream 113, as described above.

Thus, conventional processes for producing xylenes, particularly paraxylene, from a heavy petroleum naphtha stream, as illustrated in Figure 1, typically require: (i) performing vapor phase isomerization of paraxylene depleted stream 123 or at least a portion thereof to provide deethylation of ethylbenzene contained in stream 123; (ii) performing vapor phase transalkylation in transalkylation zone 147 between C9 to C10 rich aromatics stream 133 and the benzene/toluene stream to provide The C2+ alkyl groups in the C2+-hydrocarbyl substituted aromatics contained in stream 133 are dealkylated. Such vapor phase processes are energy intensive, complicate and increase the cost of aromatics manufacturing plants, and result in the loss of a source of valuable methyl substituents that could otherwise be used to make more xylene molecules. Figure 2: Exemplary inventive process for the production of xylenes from naphtha

Figure 2 illustrates an exemplary inventive process 201 for producing xylene (particularly para-xylene) product from a C6+ aromatics-containing stream comprising C2+-hydrocarbyl substituted aromatics, such as a reconstituted oil stream or hydrotreated The steam cracked petroleum brain stream. Although this exemplary process is illustrated and described primarily for the purpose of making para-xylene products, those of ordinary skill in the art will readily appreciate that this exemplary process can be modified for the purpose of making ortho-xylene, toluene, and other aromatic products. In Figure 2, a heavy petroleum brain stream 103 (having a normal boiling point in the range of, for example, 100 to 240°C, such as 120 to 220°C, or 140 to 200°C, or 140 to 180°C) will be produced by, for example, a crude oil refining process. supplied to the reorganization zone 105 . The heavy petroleum naphtha stream 103 may contain large amounts of paraffins and naphthenes. The reformation zone 105 may comprise one or more of any conventional naphtha catalyst reformation reactor known in the art (eg, a fixed bed reactor for semi-regenerative processes or a moving bed reactor for continuous regeneration processes). The recombination catalyst is arranged in the recombination zone. Upon contact with the recombination catalyst and under recombination conditions (such as those well known in the art), the hydrocarbons in the heavy petroleum naphtha stream 103 undergo a series of chemical reactions (including, but not limited to, isomerization, aromatization, dehydrocyclization, etc. etc.) to convert at least a portion of the paraffins and naphthenes to aromatics. As discussed above, in a typical recombination operation, various amounts (sometimes large) of C2+-hydrocarbyl-substituted aromatics can be produced. In Figure 2, within a portion of the recombination zone 105, or adjacent to the recombination zone and downstream of the recombination zone 105, an optional alkyl-demethylation zone (the seventh alkyl-demethylation zone according to the first aspect of the present disclosure) is installed methylated region) 203. In this optional alkyl-demethylation zone 203, an alkyl-demethylation catalyst (the seventh alkyl-demethylation catalyst according to the first aspect of the present disclosure) is configured. In one example, recombination region 105 partially or fully overlaps alkyl-demethylation region 203 . Such a configuration can be achieved by mixing a portion or all of the alkyl-demethylation catalyst in the alkyl-demethylation zone 203 with a portion or all of the recombination catalyst in the recombination zone 105 to form an aggregated catalyst mixture accomplish. In this case, at least a portion of the C2+-hydrocarbyl-substituted aromatics produced in recombination zone 105 may be converted to the desired alkyl-demethylation upon contact with an alkyl-demethylation catalyst prior to exiting recombination zone 105 Aromatic hydrocarbons. In another example, the recombined catalyst in zone 105 may form an upstream catalyst bed, and the alkyl-demethylation catalyst may form a downstream catalyst bed, and the two catalyst beds may be located in the same or different tanks. In this case, the C2+-hydrocarbyl-substituted aromatics formed in zone 107 flow to alkyl-demethylation zone 203, where the aromatics are partially converted to alkyl-demethylated aromatics, especially the desired methyl Alkylated aromatics such as toluene, xylene, and mesitylene. Due to the physically adjacent or overlapping nature of the recombination region 105 and the alkyl-demethylation region 203 (if present), the recombination conditions and the alkyl-demethylation conditions (according to the seventh set of the first aspect of the present disclosure) alkyl-demethylation conditions) may include similar or even substantially the same temperature, pressure, and the like. The alkyl-demethylation effluent 107 (the seventh alkyl-demethylation effluent according to the first aspect of the present disclosure) exiting the alkyl-demethylation zone 203 (if present) comprises C6+ Aromatics (including benzene, toluene, xylene, ethylbenzene, and C9+ aromatics). Since a portion of the C2+-hydrocarbyl-substituted aromatics produced in recombination zone 105 are converted to alkyl-demethylated aromatics in zone 203, as compared to the process without alkyl-demethylation zone 203, this leaves zone 203 The concentration of C2+-hydrocarbyl-substituted aromatic hydrocarbons in effluent 107 decreased. One advantage of locating alkyl-demethylation zone 203 very close to recombination zone 105 is that all C2+-hydrocarbyl-substituted aromatics (including C8, C9, C10, and C11+C2+-hydrocarbyl-substituted aromatics (including C8, C9, C10, and C11+C2+-hydrocarbyl substituted) present or produced in zone 105 have the advantage Alkyl-demethylation of aromatics) can be subjected to alkyl-demethylation in zone 203 to produce effluent 107 with a reduced concentration of C2+-hydrocarbyl substituted aromatics, thus allowing C2+-hydrocarbyl substituted aromatics in the downstream process load reduction. In addition to aromatic hydrocarbons, effluent 107 may also contain non-aromatic hydrocarbons, such as alkanes and naphthenes, especially azeotropes with aromatic hydrocarbons. Preferably, effluent 107 consists essentially of C6+ hydrocarbons. Additional streams such as a hydrogen stream (not shown), and a waste gas stream (not shown) containing light hydrocarbons (eg, C5-hydrocarbons) may also be produced from the reformation zone 105 and/or the alkyl-demethylation zone 203.

As shown in Figure 2, the recombination effluent (wherein the optional alkyl-demethylation zone 203 is absent) or the alkyl-demethylation effluent (wherein the optional alkyl-demethylation zone 203 is present) 107 or a portion thereof is supplied to another downstream optional alkyl-demethylation zone 205 downstream of zones 105 and 203 (the first alkyl-demethylation zone according to the first aspect of the present disclosure). In one embodiment, all of the effluent 107 of zone 105/203 is supplied to the alkyl-demethylation zone 205. In another embodiment, the effluent 107 of zone 105/203 is separated (not shown) prior to supplying a portion of the effluent 107 of zone 105/203 to the alkyl-demethylation zone 205, for example to remove part or some components. In the absence of optional alkyl-demethylation zone 203, alkyl-demethylation zone 205 receives reconstituted effluent 107. In the presence of an optional alkyl-demethylation zone, if the conversion of C2+-hydrocarbyl-substituted aromatics in zone 203 is high enough, then ideally the alkyl-demethylation zone 205 may not be present. Alternatively, alkyl-demethylation zone 205 can be installed downstream of alkyl-demethylation zone 203 to provide additional C2+-hydrocarbyl-substituted aromatics present in alkyl-demethylation effluent 107 Alkyl-demethylation processing. Similar to random zone 203, zone 205, if present, includes an alkyl-demethylation catalyst (a first alkyl-demethylation catalyst according to the first aspect of the present disclosure) disposed therein. The demethylation catalyst in zone 205 and the demethylation catalyst in zone 203 can be the same or different, if both are present. The operating conditions in zone 205 (the first set of alkyl-demethylation conditions according to the first aspect of the present disclosure) and the operating conditions in zone 203 (the seventh set of alkyl according to the first aspect of the present disclosure) - demethylation conditions) may be similar or different. If substantially all C2+-hydrocarbyl substituted aromatics are supplied to zone 205, then similar to zone 203, substantially all C2+-hydrocarbyl substituted aromatics (including C8, C9, C10, and C11+C2+-hydrocarbyl substituted aromatics) can be Subject to alkyl-demethylation conditions in zone 205, a portion thereof is converted to alkyl-demethylated aromatics. This can be advantageous because at the possible high conversions of C2+-hydrocarbyl-substituted aromatics of various molecular weights at such upstream positions, it is possible to make changes in downstream processes such as C8 aromatics isomerization and/or C6 to C7 aromatics addition. Significantly reduced loading of processing high concentrations of C2+-hydrocarbyl-substituted aromatics in C9 to C10 aromatic transalkylation) enables highly advantageous downstream processes such as liquid-phase-only isomerization and liquid-phase-only transalkylation, such as Described in more detail below. The alkyl-demethylation effluent 207 exits the alkyl-demethylation zone 205 . Effluent 207 may comprise benzene, toluene, non-aromatic azeotropes of benzene and/or toluene, xylenes, mesitylenes, aromatics substituted with C2+-hydrocarbyl groups such as ethylbenzene, methylethylbenzene, and the like. Compared to effluent 107, effluent 207 desirably contains a reduced amount of C2+-hydrocarbyl-substituted aromatic hydrocarbons.

In certain embodiments, optional alkyl-demethylation zone 203 is present, and alkyl-demethylation zone 205 is absent. Such embodiments may be advantageous in that the presence of zone 203 alone is sufficient to reduce the concentration of C2+-hydrocarbyl-substituted aromatics in stream 107 to a sufficiently low level. In certain other embodiments, zone 203 is absent and zone 205 is present. Such embodiments may be advantageous in that the recombination catalyst in recombination zone 105 has substantially different catalyst cycle times than the alkyl-demethylation catalyst in zone 205, and/or the recombination conditions in zone 105 are different from those of the alkyl-demethylation catalyst in zone 205. The alkyl-demethylation conditions in zone 205 are substantially different, requiring two different reactors. In other embodiments, both alkyl-demethylation regions 203 and 205 are present. Such embodiments may be advantageous in that in zones 203 and 205 a portion of the C2+-hydrocarbyl-substituted aromatics are converted to alkyl-demethylated aromatics, resulting in their high combined conversions. Such embodiments may be advantageous in that the recombinant catalyst may perform both recombination and alkyl-demethylation bifunctionality, and will specifically handle alkyl-demethylation rather than recombination alkyl-demethylation A catalyst is configured in zone 205 to further convert at least a portion of the C2+-hydrocarbyl-substituted aromatics present in stream 107 to alkyl-demethylated aromatics.

As shown in Figure 2, either effluent 107 (where random alkyl-demethylation zone 205 is absent) or effluent 207 (where random alkyl-demethylation zone 205 is present) is then supplied to reformed oil separator 109 (eg, a single distillation column, or a series of distillation columns), a stream 111 rich in C6 to C7 hydrocarbons and a stream 113 rich in C8+ aromatics are produced. The C6 to C7 rich hydrocarbon stream 111 contains benzene, toluene, paraffins and naphthenes azeotrope thereof. Preferably stream 111 is substantially free of C8+ aromatics. Preferably stream 111 is substantially free of C2+-hydrocarbyl substituted aromatic hydrocarbons. The C8+ aromatics-rich stream 113 may comprise C8 aromatics (eg, xylene and ethylbenzene), C9 aromatics (eg, trimethylbenzene, ethyltoluene, n-propylbenzene, cumene, and indene), C10 aromatics (eg, tetratoluene, Diethylbenzene, ethylxylene, methyl-n-propylbenzene, methyl cumene, n-butylbenzene, isobutylbenzene, secondary butylbenzene, tertiary butylbenzene, methyldihydroindene, tetrahydronaphthalene, and naphthalene) and even C11+ aromatics (eg methylnaphthalene, methyltetrahydronaphthalene). The C8+ aromatics-rich stream 113 is then optionally combined with other C8+ aromatics-rich streams such as stream 145 (described below) into a combined stream 114 that is supplied to the optional alkyl-demethylation zone 209 (in accordance with the first aspect of the present disclosure). dialkyl-demethylation region). Similar to random alkyl-demethylation zones 203 and 205 (if present), zone 209 includes an alkyl-demethylation catalyst (the second alkyl group according to the first aspect of the present disclosure) disposed therein - demethylation catalyst). The alkyl-demethylation catalyst in zone 209 and the alkyl-demethylation catalyst in zone 203 and/or 205 can be the same or different. Zone 209 is operated under one set of alkyl-demethylation conditions (a second set of alkyl-demethylation conditions in accordance with the first aspect of the present disclosure) to effect alkyl-demethylation in contact therein At least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbons are converted into alkyl-demethylated aromatic hydrocarbons (especially methylated aromatic hydrocarbons) when the catalyst is alkylated. Including zone 209 in the process can be particularly advantageous in that stream 113 and/or stream 145 and stream 114 contain significant amounts of C2+-hydrocarbyl substituted aromatic hydrocarbons.

Combined stream 114 is rich in C8+ aromatics and depleted in benzene, toluene, and azeotropes thereof. Preferably, stream 114 comprises benzene and toluene in a total concentration of &lt; 5 wt%, based on their total weight, such as &lt; 2 wt%, &lt; Since the C2+-hydrocarbyl substituted aromatics are all C8+ aromatics, compared to stream 207, stream 113 is rich in C2+-hydrocarbyl substituted aromatics. If stream 145 contains any significant amounts of C2+-hydrocarbyl-substituted aromatics, stream 145 is preferably combined with stream 113 (as shown in FIG. 2) and then fed to alkyl-demethylation zone 209. However, if stream 145 is substantially free of C2+-hydrocarbyl substituted aromatics, it is preferred to supply stream 145 directly to xylene separator 115 (described below) bypassing alkyl-demethylation zone 209 (if present). The advantage of including an alkyl-demethylation zone 209 in the process is to reduce the loading of C2+-hydrocarbyl substituted aromatics in subsequent processes such as isomerization and transalkylation. In alkyl-demethylation zones 203 and 205, a typical upper alkyl-demethylation process is carried out in the presence of significant amounts of benzene, toluene, and their azeotropes. On the other hand, the alkyl-demethylation in zone 209 can be carried out in the presence of much lower amounts of benzene and toluene in the reaction mixture because feed stream 114 can contain much lower concentrations than streams 107 and 207 Toluene. Since the desired product of the alkyl-demethylation process is toluene, the lower toluene concentration of stream 114 may favor a higher conversion of C2+-hydrocarbyl substituted aromatics in zone 209 than in zones 203 and 205. Stream 211 exiting zone 209 (the second alkyl-demethylation effluent according to the first aspect of the present disclosure) may contain, in addition to C8+ aromatics, toluene produced by the alkyl-demethylation reaction.

Preferably, at least one of regions 203, 205, and 209 is present in the process flow of the aromatics manufacturing process (including the heavy naphtha reformation step) because, as mentioned above, heavy naphtha reformation produces significant amounts of C2+-hydrocarbyl substitution the tendency of aromatic hydrocarbons. In the alkyl-demethylation step, methylated benzene and/or can be made by converting a C2+ alkyl or carbon atom in a ring fused to the benzene ring to one or more methyl groups attached to the benzene ring or increased benzene production, as described above. In certain embodiments of the method of the first aspect of the present disclosure, only one of the optional alkyl-demethylation regions 203, 205, and 209 is present. Such a single alkyl-demethylation zone may be advantageous in that the single zone is capable of converting C2+-hydrocarbyl substituted aromatics to a sufficient degree. In other embodiments, especially where stream 145 does not contain significant amounts of C2+-hydrocarbyl-substituted aromatics, both zones 203 and 205 may be present to achieve sufficient conversion of C2+-hydrocarbyl-substituted aromatics, while zone 209 does not exist. In other embodiments, particularly where stream 145 contains significant amounts of C2+-hydrocarbyl-substituted aromatic hydrocarbons, zone 209 and either (but not necessarily both) of zones 203 and 205 may be present. In other embodiments, especially in embodiments in which a significant amount of C2+-hydrocarbyl-substituted aromatics are produced in the recombination zone or present in stream 103, in order to maximize the conversion of C2+-hydrocarbyl-substituted aromatics, it may be desirable to All three zones 203, 205, and 209 are included in the method flow.

As shown in Figure 2, effluent 211 and/or stream 114 that would exit alkyl-demethylation zone 209 (if present) (if zone 209 was not present and/or if stream 114 partially bypassed zone 209) or A portion thereof is fed to a xylene separator 115 (eg, a distillation column), producing a xylene-rich stream 117 and a C9+ aromatics-rich stream 129. In embodiments where zone 209 exists, a portion of the C2+-hydrocarbyl substituted aromatics (C2+ alkyl monosubstituted aromatics, e.g. ethylbenzene, n-propylbenzene, e.g. , cumene, etc.) into toluene. In such embodiments, a C7-aromatics stream (not shown) may also be produced from xylene separator 115. The C7-aromatics stream produced from 115 may be supplied to extraction zone 137, for example. Xylene-rich stream 117 contains xylene and various concentrations of ethylbenzene, depending on whether one or more of zones 203, 205, and 209 are present, among others. As discussed above, the presence of one or more of zones 203 , 205 , and 209 reduces the amount of ethylbenzene in stream 117 as compared to the corresponding stream in the process of FIG. 1 where none of zones 203 , 205 , and 209 are present. The ethylbenzene concentration in stream 117 in FIG. 2 may be in the range of c(EB)3 to c(EB)4 wt % based on the total weight of C8 aromatics contained in stream 117, where c(EB)3 and c (EB)4 can independently be, for example, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24 , 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, as long as c(EB)3<c(EB)4. In some cases, the ethylbenzene concentration may be low such that c(EB)4≤20, c(EB)4≤10, c(EB)4≤5, or even c(EB)4≤1. Stream 117 in FIG. 2 may contain various concentrations of para-xylene, depending on the composition of the C8+ aromatics-rich stream supplied to xylene separator 115. For example, stream 117 may comprise paraxylene at a concentration of c(pX)1 to c(pX)2 wt %, based on the total weight of C8 aromatics contained in stream 117, where c(pX)1 and c( pX)2 can independently be, for example, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 48, 50, 52, 54, 55, 56, 58, 60, as long as c(pX)1 <c(pX)2.

As shown in FIG. 2, similar to the conventional process of FIG. 1, the xylene-rich stream 117 produced by the xylene separator 115 is then supplied to the first para-xylene recovery sub-system 119 to produce a first para-xylene-rich Para-xylene product stream 121 and first para-xylene depletion stream 123. The first paraxylene depleted stream 123, which is relatively rich in meta-xylene, ortho-xylene, and ethylbenzene with stream 117, is then partially (as shown by stream 215) or fully supplied to first isomerization zone 125, wherein meta-xylene and/or ortho-xylene is isomerized under a first set of isomerization conditions in the presence of a first isomerization catalyst to form additional para-xylene. The isomerization effluent 217 or a portion thereof (shown as stream 127 ) is then supplied to the xylene separator 115 . Xylene separator 115, para-xylene recovery subsystem 119, and isomerization zone 125 form a xylene loop.

In the conventional process of Figure 1, if isomerization zone 125 does not have sufficient capacity to convert the ethylbenzene contained in stream 123, ethylbenzene undesirably accumulates to high concentrations over time in the xylene loop. To prevent ethylbenzene from accumulating in the xylene loop, especially where streams 113, 145, 117, and 123 contain significant concentrations of ethylbenzene (eg, ≥ 10 wt% based on the total weight of C8 aromatics contained therein), typically The isomerization catalyst and isomerization conditions in the isomerization zone above in the conventional process of Figure 1 are selected such that at least a portion of the ethylbenzene is converted to benzene by deethylation under vapor phase isomerization conditions. Deethylation results in the conversion of the ethyl groups in the ethylbenzene molecule to ethane (in the presence of molecular hydrogen and the hydrogenation function of the deethylation catalyst used in the isomerization zone). Deethylation of ethylbenzene results in the loss of the ethyl substituent bound to the benzene ring. Substantially vapor phase isomerization of xylenes requires heating the hydrocarbons to high temperature in the isomerization zone, followed by cooling and condensation of the isomerization effluent to a liquid state for separation in xylene separator 115, and is therefore expensive. can.

As shown in Figure 2, provided that streams 123 and 215 may contain significant amounts of ethylbenzene, in Figure 2 the first isomerization zone 125 may be operated under vapor phase conditions to convert at least a portion of the ethylbenzene by deethylation such that The amount of ethylbenzene in the xylene loop is not too high, similar to the conventional process of Figure 1 including an isomerization zone operating under vapor phase conditions.

However, in the process of FIG. 2, due to the presence of at least one of zones 203, 205, and 209, and the resulting reduction in the amount of ethylbenzene in stream 117 compared to the corresponding stream in FIG. The need for deethylation of ethylbenzene is reduced, thus reducing the need for vapor phase isomerization conditions in zone 205. Accordingly, at least a portion, ideally most, and even all of the paraxylene depleted stream 123 may be processed under isomerization conditions in zone 125 such that the C8 aromatics therein are substantially liquid phase. Because such liquid phase isomerization is carried out at significantly lower operating temperatures than the conventional vapor phase isomerization required in the process of Figure 1, there is substantial energy savings and a substantial increase in energy efficiency. As shown in FIG. 2 , the paraxylene depleted stream 123 is split into streams 213 and 215 . Stream 215 is supplied to isomerization zone 125, which preferably operates under liquid phase isomerization conditions. Stream 213, or a portion thereof, may be directed away as a purge stream of, for example, a molar gas admixture. Diverting stream 213, or a portion thereof, from the xylene loop can reduce the amount of ethylbenzene circulating in the loop. Additionally or alternatively, stream 213 or a portion thereof may be recycled (not shown) to any of zones 203, 205, and 209 (if present), preferably any of zones 205 and 209 (if present) or more preferably zone 209 (if present), especially if the amount of ethylbenzene in stream 123 has reached a very high level. Additionally or alternatively, stream 213, or a portion thereof, can be supplied to a second isomerization zone (not shown, which can be operated under vapor phase conditions) to isomerize xylenes and ethyl acetate by deethylation in a conventional manner Benzene conversion. The effluent of the second isomerization zone, or a portion thereof, may also be supplied to xylene separator 115 after optional separation of light and/or non-aromatic hydrocarbons.

Compared to stream 215, first isomerization effluent 217 exiting first isomerization zone 125 is enriched in para-xylene. A portion (shown as stream 127) or all (not shown) of stream 217 is then supplied to a xylene separator in order to recover para-xylene from stream 217. If zone 125 is operated under vapor phase isomerization conditions, stream 217 may contain light and non-aromatic hydrocarbons resulting from deethylation in addition to aromatics such as xylenes and ethylbenzene. Streams 217 and/or 127 may be separated to remove such light and non-aromatic hydrocarbons (not shown) prior to feeding to xylene separator 115. If zone 125 is operated under liquid phase isomerization conditions without deethylating ethylbenzene, stream 217 tends to contain significantly more than the corresponding effluent stream leaving the isomerization zone (if any) under vapor phase conditions Lower amounts of such light and non-aromatic hydrocarbons. Thus, stream 217, or a portion thereof (as shown by stream 127) exiting liquid phase isomerization zone 125, can be supplied directly to xylene separator 115 without intermediate separation steps (optional heating/cooling, etc.). The isomerization of substantially all of the para-xylene depleted stream 123 in the liquid phase isomerization zone alone without the use of a vapor phase isomerization zone clearly results in a comparison of the conventional process of Figure 1 with the need for a vapor phase isomerization zone , a simpler, less energy-consuming, and more energy-efficient xylene circuit.

As shown in FIG. 2 , the first isomerization effluent 217 is split into streams 127 and 219 . After optional further intermediate separation (as the case may be), stream 217, or a portion thereof, is supplied to xylene separator 115. Stream 219, or a portion thereof, may be directed away as a wash stream and used, for example, for a motor gasoline blend. Additionally or alternatively, stream 219, or a portion thereof, may be recycled (not shown) to one or more of zones 203, 205, and 209 (if present), preferably one of zones 205 and 209 (if present) Alternatively, and preferably, zone 209 (if present), where the ethylbenzene contained can be converted to more valuable molecules via alkyl-demethylation. Additionally or alternatively, stream 219, or a portion thereof, may be recycled (not shown) directly to paraxylene recovery subsystem 119 bypassing xylene separator 115 to recover a portion of paraxylene therein. Bypassing the xylene separator can further improve the energy efficiency of the xylene loop. The isomerization effluent from the vapor phase isomerization zone typically contains light hydrocarbons and other non-aromatic hydrocarbons resulting from, for example, dealkylation, and therefore does not have intermediate separation steps (eg, in a deheptanizer and/or xylene separator). 115) is not directly recycled to the p-xylene recovery sub-system. Conversely, the isomerization effluent from the liquid phase isomerization zone contains much lower concentrations of such light hydrocarbons and other non-aromatic hydrocarbons than typical vapor phase isomerization effluents, if any, and therefore can The additional para-xylene formed in the isomerization zone is recycled directly to the para-xylene recovery subsystem, bypassing the xylene separator. Liquid phase isomerization zone 125 is optionally combined to recycle streams 213 and/or 217 or a portion thereof to one or more of alkyl-demethylation zones 203, 205, and 209 or can completely eliminate the paraxylene loop The need for a vapor-phase isomerization zone in the system results in an overall higher energy efficiency, and a more valuable formaldehyde, compared to conventional processes that require the use of a vapor-phase isomerization zone in the xylene loop as illustrated in Figure 1. Alkylated aromatics yield. Conversion of a portion of C2+-hydrocarbyl-substituted aromatics to methylated aromatics in zones 203, 205, and/or 209 enables the implementation of the conventional process of Figure 1 and dealkylation of at least a portion of ethylbenzene in a vapor phase isomerization zone In comparison, more xylene yields.

As shown in FIG. 2, similar to FIG. 1, the sum stream 211 produced by the xylene separator 115 is then separated in distillation column 131 to obtain a C9+aromatics stream 129 rich in C9, C10, and C11+aromatics to obtain C9-rich to C11+aromatics C10 aromatics stream 133 and C11+ aromatics stream 135 . Stream 135 may be directed away and used, for example, as a motor gasoline blend, fuel oil, or the like. C9 to C10 rich aromatics stream 133 is rich in, for example, methylated aromatics (such as tritoluene and tetratoluene), and C2+-hydrocarbyl substituted aromatics (such as ethyltoluene, dihydroindene, ethylxylene, diethylbenzene, methylbenzene indane, tetrahydronaphthalene, methyltetrahydronaphthalene, etc.). Stream 133 is then supplied along with benzene/toluene rich stream 146 to transalkylation zone 147 in which the transalkylation catalyst is disposed. Alternatively, a portion or all of stream 129 may be supplied to transalkylation zone 147 . In the presence of a transalkylation catalyst and under transalkylation conditions, C9+ aromatics are reacted with benzene/toluene to produce xylenes. Typically, streams 129 and 133 produced from the reconstituted oil stream as illustrated in Figure 1 contain substantial amounts of C2+-hydrocarbyl substituted aromatics. Direct transalkylation between such C9 to C10 C2+-hydrocarbyl substituted aromatics and benzene/toluene yields ethylbenzene and other C9+C2+-hydrocarbyl substituted aromatics. To increase xylene and/or benzene/toluene production in transalkylation zone 147, typically in the process of Figure 1 the transalkylation catalyst and transalkylation conditions are selected such that in the transalkylation zone At least a portion of the C9 to C10 C2+-hydrocarbyl-substituted aromatic hydrocarbons and ethylbenzene are converted to toluene and/or benzene through the complete dealkylation of the aromatic rings of the C2+ alkyl group. Dealkylation results in the conversion of C2+ alkyl groups to light hydrocarbons (typically in the presence of molecular hydrogen and the hydrogenation function of the dealkylation catalyst used in the transalkylation zone). Therefore, it is a loss to remove the C2+ alkyl groups in order to make xylenes. The C2+ alkyl group is preferably converted to a methyl group attached to the benzene ring - which can then be used to make xylenes via, for example, isomerization, transalkylation, and/or disproportionation. Similar to the deethylation of ethylbenzene, efficient dealkylation of C9 to C10 C2+-hydrocarbyl substituted aromatics with ethylbenzene in the transalkylation zone typically requires vapor phase conditions that require high temperatures. Such vapor phase transalkylation is energy intensive because of the need to cool and condense the vapor effluent of the transalkylation zone to a liquid for distillative separation.

However, in the inventive process of Figure 2, due to the presence of one or more of zones 203, 205, and 209, the amount of C2+-hydrocarbyl-substituted aromatics in streams 129 and 133 is significant compared to the corresponding streams in the process of Figure 1 Reduced because a significant portion of such C9+C2+-hydrocarbyl substituted aromatics can be converted to methylated aromatics in zones 203, 205, and/or 209. The low concentrations of C2+-hydrocarbyl-substituted aromatics in streams 129 and 133 significantly reduce the need for dealkylation in transalkylation zone 147. The reduced need for dealkylation enables transalkylation to be achieved in zone 147 at temperatures significantly lower than conventional vapor phase transalkylation processes requiring dealkylation such that some or even all of it is present in zone 147. The C8 aromatics in 147 are in the liquid phase. Such partial liquid phase or full liquid phase transalkylation can result in substantial energy savings and a substantial increase in energy efficiency compared to conventional full vapor phase transalkylation required for dealkylation. Conversion of a portion of the C2+-hydrocarbyl substituted aromatics to methylated aromatics in zones 203, 205, and/or 209 can also be achieved and dealkylation of at least a portion of the C2+-hydrocarbyl substituted aromatics in the transalkylation zone. 1 compared to the traditional method, more xylene yield.

In traditional transalkylation processes involving dealkylation of C2+-hydrocarbyl-substituted aromatics, a portion of the C2+ alkyl groups and/or aliphatic rings fused to the aromatic ring are converted to light hydrocarbons, and due to the aromatic ring Loss of non-aromatic hydrocarbons may be produced. Therefore, it may be necessary to separate the transalkylation effluent to remove such light and non-aromatic hydrocarbons (eg, through a deheptanizer, not shown) prior to supplying it to an aromatics separation column (eg, benzene column 141 in Figure 1 ) . In the embodiment of the process of the invention of Figure 2, the opposite is true because the small amount of C2+-hydrocarbyl substituted aromatics in stream 133 minimizes or eliminates dealkylation of the C2+-hydrocarbyl substituted aromatics, and the transalkylation effluent Product 149 contains light hydrocarbons and such small amounts of non-aromatic hydrocarbons (if any) that effluent 149 can be supplied directly to benzene column 141 without an intermediate separation step to remove light and non-aromatic hydrocarbons (on optional heating/cooling etc. wait, as the case may be). Thus, the presence of one or more alkyl-demethylation zones in the process of Figure 2 enables a simpler transalkylation process that requires less equipment and steps but also significantly saves energy and improves energy efficiency. Stream 149 in Figure 2 may contain, for example, benzene, toluene, xylenes, mesitylenes, tetratoluenes, and desirably small amounts of C8, C9, C10, and C11+C2+-hydrocarbyl substituted aromatic hydrocarbons.

In certain embodiments, > 50 wt%, or > 60 wt %, or > 70 wt %, or > 80 wt %, or > 90 wt %, or > 95 wt %, or > 98 wt % of stream 133 are methylated aromatic hydrocarbons. Thus, most of the reactions in transalkylation zone 147 may be the exchange of methyl groups between aromatics (such as benzene, toluene, trimethylbenzene, and tetratoluene), resulting in a net production of xylenes and C9 to C10 methylated aromatics, and benzene and/or toluene consumption. Preferably, such transalkylation is carried out in the liquid phase, wherein (i) the C8 aromatics present in the transalkylation zone are substantially liquid phase; and/or (ii) are present in the transalkylation Aromatics (including benzene) in the zone are in a substantially liquid phase. Transalkylation effluent 149 may contain benzene, toluene, xylenes, C9+ methylated aromatics, and minor amounts of C8+C2+-hydrocarbyl substituted aromatics.

As shown in Figure 2, stream 149 is then supplied to benzene column 141 to separate the aromatics contained therein to obtain benzene product stream 143, toluene-rich and/or benzene-rich stream 146 (which is partially or fully fed to transalkylation zone 147), and C8+ aromatics-rich stream 145 (comprising xylenes, C9+ methylated aromatics, and small amounts of C8+C2+-hydrocarbyl-substituted aromatics), which is fed to xylene separator 115, as described above .

Thus, in the inventive process of Figure 2 of the present disclosure, by utilizing one or more of the alkyl-demethylation zones 203, 205, and 209 in the process, it is possible to allow access to the xylene loop and/or transalkylation The amount of aromatics substituted by C2+-hydrocarbyl groups in the alkylation zone is significantly reduced. The reduction in the amount of ethylbenzene in the xylene loop reduces the need for ethylbenzene deethylation, reduces or eliminates the need for vapor phase isomerization, and enables only liquid phase isomerization, resulting in (i) less need for Equipment, lower operating temperature, lower energy intensity, simpler xylene loop with higher energy efficiency, and (ii) higher xylene productivity in the xylene loop. The reduction in the amount of C9+C2+-hydrocarbyl substituted aromatics in the feed to the transalkylation zone reduces the need for dealkylation of C9+C2+-hydrocarbyl substituted aromatics and reduces or eliminates the need for vapor phase transalkylation , and the ability to achieve only liquid phase transalkylation, resulting in (i) a simpler transalkylation process that requires less equipment, lower operating temperatures, lower energy intensity, and higher energy efficiency, and (ii) Higher production rates of methylated aromatics (especially xylenes) in the transalkylation zone.

As shown in FIG. 2 , similar to FIG. 1 , a C6 to C7 rich hydrocarbon stream 111 is supplied to an extractive distillation zone 137 where a C6 to C7 aromatics rich stream 139 and an aromatics depleted raffinate stream 138 are produced. Stream 138, which is richer in non-aromatic hydrocarbons than stream 111, can be directed away and used as, for example, a motor gasoline blendstock. Stream 139 is then supplied to benzene column 141 to produce benzene product stream 143, toluene-rich stream 146, and C8+ aromatics-rich stream 145. Toluene-rich stream 146 (or a portion thereof) is supplied to transalkylation zone 147 along with C9 to C10 aromatics-rich stream 133, as described above. C8+ aromatics-rich stream 145 is then fed to xylene separator 115 along with stream 113, as described above.

In the process of the invention of Figure 2, a portion of the C2+-hydrocarbyl-substituted aromatics produced in zone 105 and/or present in stream 107 are converted to methyl groups if one or both of zones 203 and 205 are present Aromatic hydrocarbons (including toluene). For example, ethylbenzene is at least partially converted to toluene, and C9+ arenes substituted with one C2+ alkyl group can be alkyl-demethylated to produce toluene. The amount of toluene in stream 207 can be increased in such embodiments as compared to the absence of zones 203 and 205. Accordingly, one embodiment of the present process that includes one or both of zones 203 and 205 can produce higher amounts of toluene in streams 111 , 139 , and 146 . As discussed above, in the presence of zone 209, stream 211 contains toluene converted from, for example, ethylbenzene and C9+ aromatics monosubstituted with C3+ alkyl groups. Toluene present in stream 211 may be separated in xylene separator 115 (not shown) and then supplied to aromatics extraction zone 137, resulting in an increase in the amount of toluene in streams 139 and 146. The increased toluene production in stream 146 may be used at least in part in transalkylation zone 147 to produce additional quantities of xylenes, as illustrated in FIG. 2 . However, in the comparative process shown in Figure 1 and discussed above, in the absence of any of zones 203, 205, and 209, typically in the vapor phase isomerization zone 125 and/or vapor phase transparaffin The C2+-hydrocarbyl-substituted aromatic hydrocarbons present in stream 107 are converted to benzene in the alkylation zone 147 by dealkylation. Therefore, the amount of benzene product stream 143 may be lower in the process of FIG. 2 than in the conventional process of FIG. 1 . Although benzene is a valuable industrial chemical, the paraxylene that can be produced from the increased amount of toluene in stream 146 would be of significantly higher economic value than the reduced benzene production in stream 143.

Alternatively or additionally, at least a portion of the toluene-rich stream 146 may be supplied to a toluene disproportionation zone (not shown), where the toluene contacts a disproportionation catalyst disposed therein under disproportionation conditions to produce a xylene-rich disproportionation effluent. Any toluene disproportionation catalyst and reaction conditions can be used to convert at least a portion of stream 146. The disproportionation catalyst preferably has a shape selectivity for the yield of para-xylene over the yield of meta-xylene and ortho-xylene, and can achieve a high para-xylene concentration based on all C8 aromatics in the disproportionation effluent. The high purity paraxylene product is conveniently isolated from the high paraxylene concentration C8 aromatic mixture using, for example, efficient crystallization techniques known in the art. In FIG. 2 , a portion of the disproportionation effluent, such as the filtrate of the crystallization separation step, may be supplied to para-xylene recovery subsystem 119 to produce para-xylene product stream 121 . Toluene disproportionation methods, catalysts, and conditions are described, for example, in US Pat. Nos. 5,476,823 and 6,486,373, which are hereby incorporated by reference in their entirety.

Alternatively or additionally, at least a portion of the toluene-rich stream 146 and/or a portion of the benzene product stream 143 may be supplied to the methylation zone along with a methylating agent feed (not shown). Upon contacting the methylation catalyst disposed in the methylation zone under methylation conditions, the benzene/toluene reacts with the methylating agent to produce a methylation effluent comprising xylenes. Preferred methylating agents are methanol, dimethyl ether, and mixtures thereof. The methylation zone may include fixed bed reactors, fluid bed reactors, moving bed reactors, and the like. The xylene produced in the methylation zone and present in the methylation effluent can be separated from other components (benzene/toluene, methylating agent, etc.) and then at least partially supplied to para-xylene recovery Subsystem 119, produces an additional amount of para-xylene product in stream 121 from 119. Methylation methods, catalysts, and conditions are described, for example, in US Pat. Nos. 5,939,597 and 6,423,879, which are hereby incorporated by reference in their entirety. Figure 4: Exemplary inventive process for the production of xylenes from hydrotreated steam cracked naphtha ("SCN")

In petrochemical plants, light naphtha from crude oil refining can be fed to a pyrolysis reactor called a steam cracker (comprising a coiled tube section located in a heating furnace), where first in the convection zone of the coiled tube Heating hydrocarbons in light petroleum naphtha to medium temperature followed by brief heating to high temperature in a radiant zone to achieve pyrolysis, producing a steam cracking mixture containing hydrogen, high value chemicals such as olefins (e.g. ethylene, propylene, butylene) alkene, etc.), steam cracked naphtha, gas oil and tar. The rapidly quenched steam cracked mixture can be separated upon exiting the steam cracker to obtain various olefinic products, hydrogen products, fuel gas, SCN stream, gas oil stream, and tar stream. The SCN stream (containing aromatics and non-aromatics) is then typically hydrotreated to saturate the olefinic substituents on the diolefinic and olefinic non-aromatics and/or olefinic arenes. Hydrotreating the SCN can also reduce heteroatoms (eg, sulfur and nitrogen) present in certain compounds in the SCN to reduce or prevent catalysts used in downstream processes (eg, alkyl-dealkylation used in the methods of the present disclosure). methylation catalyst) poisoning. Valuable aromatics can be extracted and/or produced from the hydrotreated SCN stream.

Figure 3 illustrates a prior art method of processing a typical hydrotreated SCN stream. In this figure, the hydrotreated SCN stream 303 is first supplied to a separation system 305 (eg, one or more distillation columns) to obtain a C5-rich stream 307, a C7+ hydrocarbon-rich or C8+ hydrocarbon-rich stream 309, and Benzene or C6 to C7 rich aromatics stream 311. Stream 311 (comprising benzene and its non-aromatics azeotrope and optional toluene and its non-aromatics azeotrope) is then supplied to extractive separation zone 313 to obtain an aromatics-rich stream 317 consisting essentially of benzene and optional toluene and a non-aromatic raffinate stream 315. Stream 315 may be directed away and used, for example, as a motor gasoline blend, fuel oil, or the like. Stream 317 (if containing substantial amounts of toluene) can be supplied to benzene column 319 to produce a benzene product stream 321 consisting essentially of benzene and a toluene-rich stream 323. The C7+ aromatics or C8+ aromatics rich stream 309 produced by the separation sub-system 305 is typically directed away as, for example, a motor gasoline blendstock.

The C7+ aromatics or C8+ aromatics contained in stream 309 (similar to a reconstituted oil stream made from a heavy petroleum naphtha stream) can contain substantial amounts of C2+-hydrocarbyl substituted aromatics in addition to toluene, xylenes, and C9+ methylated aromatics. Since para-xylene, ortho-xylene, toluene, and benzene products can have higher economic value than motor gasoline blendstocks, the production of one or more of the above-mentioned aromatic products from a hydrotreated SCN stream is critical to operating petroleum brain stream cracking A petrochemical plant would have significant economic benefits. The hydrotreated SCN stream may contain a higher weight percent of C2+-alkyl substituted aromatics, based on the total weight of C8+ aromatics contained therein, as compared to typical reconstituted oils made from heavy petroleum naphtha. In addition, the hydrotreated SCN stream may contain significantly higher concentrations of dihydroindene and dihydroindene derivatives than the reconstituted oil stream, which are difficult to convert to xylenes by transalkylation of lighter aromatics. Due to the high concentration of C2+-hydrocarbyl substituted aromatics in a typical hydrotreated SCN stream, it has traditionally been considered an undesirable and even uneconomical source of xylene products.

FIG. 4 illustrates the present process 401 for producing para-xylene product and/or benzene product from hydrotreated SCN stream 403 . In this figure, the hydrotreated SCN stream 403 is first supplied to the separation subsystem 405, resulting in a light hydrocarbon stream 407 rich in C5- hydrocarbons and a stream 107 rich in C6+ hydrocarbons. Stream 107 may be similar to the corresponding stream in FIG. 2 and thus may be similarly processed by the same downstream methods and equipment in FIG. 2 , as shown in FIG. 4 . Thus, in a petrochemical plant comprising a steam cracker and a heavy petroleum naphtha reformer, stream 107 produced from the separation of the hydrotreated SCN in Figure 4 can be combined with the reformed oil produced from the reformation zone, optionally at Co-processed in an alkyl-demethylation zone 205 and then supplied to a reformed oil separator 109. Para-xylene (and optionally ortho-xylene), benzene, and possibly other aromatic products can be produced by the inventive process of the present disclosure from heavy petroleum naphtha streams and hydrotreated SCN streams. In demethylation zones 205 and/or 209, a substantial portion of the C2+-hydrocarbyl-substituted aromatics contained in stream 107 from hydrotreated SCN stream 403 may be converted to methylated aromatics, which in turn may is converted to para-xylene product (and/or ortho-xylene product). Inclusion of zones 205 and/or 209 in the process of Figure 4 results in a significant reduction in the amount of C2+-hydrocarbyl substituted aromatics in the xylene loop and/or C9+ aromatics fed to the transalkylation zone, enabling low temperature and/or liquid Implementing isomerization and/or transalkylation off-phase reduces or eliminates the need for complex and energy-intensive vapor phase isomerization and/or vapor phase transalkylation, and results in and prior art of Figure 3 The method compares the yield of higher value products, with C7+ hydrocarbon-rich or C8+ hydrocarbon-rich stream 309 being used for the motor gasoline blendstock. If stream 107 contains a greater amount of C2+-hydrocarbyl-substituted aromatics than the corresponding stream in FIG. 2, the inclusion of zones 205 and/or 209 in the process of FIG. 4 for processing the hydrotreated SCN stream may be shown in FIG. 4's method is even more obvious.

The inventive method of Figure 4 can be modified to eliminate alkyl-demethylation regions 205 and 209. In such a case, if stream 107 can contain large amounts of C2+-hydrocarbyl substituted aromatics, stream 117 can contain large amounts of ethylbenzene, and streams 129/133 can contain large amounts of C9+C2+-hydrocarbyl substituted aromatics, it will The use of vapor phase isomerization to achieve ethylbenzene deethylation in 125 and vapor phase transalkylation to achieve C9+ aromatics dealkylation in transalkylation zone 147 results in (i) more energy and an energy-inefficient xylene loop; (ii) a more energy-intensive and less energy-intensive transalkylation process; and (iii) and as shown in FIG. 4 including either or both alkyl-demethylation zones 205 and 209 Compared to the method shown in the diagram, smaller quantities of valuable products (eg, para-xylene) are produced.

Heavy naphtha and indeed even crude oil or fractions thereof (eg fractions separated using flash drums) can be subjected to pyrolysis (eg, steam cracking) to produce hydrocarbon mixtures comprising C6+ aromatics, including C8 aromatics. In the process illustrated in Figure 4 and similar processes of the present disclosure, any C6+ aromatics in the hydrocarbon mixture can be used in place of or combined with the hydrotreated SCN stream 401, even though such C6+ aromatics may contain substantial amounts of C2+-hydrocarbyl substituted aromatics. Figure 5: Exemplary inventive process for the isomerization of C8 aromatics

Another aspect of the present disclosure pertains to a C8 aromatics isomerization process, an example 501 of which is illustrated in FIG. 5 , which is a modification of the prior art process shown in FIG. 1 .

In Figure 5, similar to Figure 1, stream 114 (the combination of streams 113 and 145) is fed to xylene separator 115, producing xylene-rich stream 117 and C9+ aromatics-rich stream 129. Xylene-rich stream 117 contains xylenes and ethylbenzene. In Figure 5 the ethylbenzene concentration in stream 117 may be in the range of c(EB)5 to c(EB)6 wt % based on the total weight of C8 aromatics contained in stream 117, where c(EB)5 and c(EB)6 can independently be e.g. 35, 36, 38, 40, as long as c(EB)5<c(EB)6. In some cases, the ethylbenzene concentration can be high such that c(EB)5≥10, c(EB)5≥15, c(EB)5≥20, or even c(EB)5≥25. Stream 117 in FIG. 5 may contain various concentrations of para-xylene, depending on the composition of the C8+ aromatics-rich stream supplied to xylene separator 115. For example, stream 117 may comprise paraxylene at a concentration of c(pX)5 to c(pX)6 wt % based on the total weight of C8 aromatics contained in stream 117, where c(pX)6 and c(pX) 7 can independently be e.g. 54, 55, 56, 58, 60, as long as c(pX)6<c(pX)7.

As shown in FIG. 5, similar to the conventional process of FIG. 1, the xylene-rich stream 117 produced by the xylene separator 115 is then supplied to the first para-xylene recovery sub-system 119 to produce a first para-xylene-rich Para-xylene product stream 121 and first para-xylene depletion stream 123. The first para-xylene depleted stream 123, which is richer in meta-, ortho-, and ethylbenzene than stream 117, is then partially (as shown by stream 511) or fully supplied to random alkyl-demethylation (ie, primarily ethyl-demethylation) region 503, which has an alkyl-demethylation catalyst (ie, an ethyl-demethylation catalyst) disposed therein. FIG. 5 shows the splitting of stream 123 into streams 509 and 511. Stream 509, or a portion thereof, especially if it contains very high concentrations of ethylbenzene, can be directed away as a wash stream and as, for example, a motor gasoline admixture. Additionally or alternatively, stream 509, or a portion thereof, may be supplied directly to an optional isomerization zone (not shown), such as a vapor phase isomerization zone containing an isomerization catalyst contained therein. Upon contact with the isomerization catalyst and under isomerization conditions, the xylenes present in stream 509 are isomerized to form additional para-xylene, and a portion of the ethylbenzene therein may be deethylated to reduce The amount of ethylbenzene in the xylene loop. The isomerization effluent of such an optional isomerization zone, or a portion thereof, may then be supplied to xylene separator 115.

On contact with the alkyl-demethylation catalyst and under alkyl-demethylation conditions, a portion of the ethylbenzene contained in stream 511 is demethylated to form toluene. Thus, compared to stream 511, the alkyl-demethylation effluent 505 exiting zone 503 is depleted of ethylbenzene. Stream 505 is then supplied to optional alkyl-demethylation zone 507 with another alkyl-demethylation catalyst disposed therein under another set of alkyl-demethylation conditions to achieve additional ethyl acetate Ethyl-demethylation of benzene. The alkyl-demethylation catalyst and alkyl-demethylation conditions in zones 503 and 507 can be the same or different, if both zones are present. Although one of zones 503 and 507 may not be present, at least one is present in the xylene loop to effect ethyl-demethylation of ethylbenzene. The alkyl-demethylation zone 507 and the isomerization zone 125 may exist in different tanks. Alternatively, zones 507 and 125 may be different but housed in the same tank (eg, where the ethyl-demethylation catalyst bed in zone 507 is located upstream of the isomerization catalyst bed in zone 125 in a common reactor tank ). Alternatively, zones 507 and 125 may partially overlap in the same tank (eg, where a portion but not all of the ethyl-demethylation catalyst in zone 207 is mixed with a portion but not all of the isomerization catalyst in zone 125 ). Alternatively, zones 507 and 125 can be substantially the same zone (eg, wherein all of the ethyl-demethylation catalyst in zone 507 is blended with all of the isomerization catalyst in zone 125 in a common reactor tank; or wherein Common catalysts can exhibit both isomerization and ethyl-demethylation functions). In isomerization zone 125, meta-xylene and/or ortho-xylene is isomerized under a first set of isomerization conditions in the presence of a first isomerization catalyst to form additional para-xylene. Isomerization zone 125 may operate under liquid phase conditions, vapor phase conditions, or mixed phase conditions.

The isomerization effluent 127 or a portion thereof (shown as stream 513 ) is then supplied to the xylene separator 115 . Xylene separator 115 , para-xylene recovery subsystem 119 , and isomerization zone 125 form a xylene loop.

In the conventional process of Figure 1, if isomerization zone 125 does not have sufficient capacity to convert the ethylbenzene contained in stream 123, ethylbenzene undesirably accumulates to high concentrations over time in the xylene loop. To prevent ethylbenzene from accumulating in the xylene loop, especially where streams 113, 145, 117, and 123 contain significant concentrations of ethylbenzene (eg, ≥ 10 wt% based on the total weight of C8 aromatics contained therein), typically The isomerization catalyst and isomerization conditions in the isomerization zone above in the conventional process of Figure 1 are selected such that at least a portion of the ethylbenzene is converted to benzene by deethylation under vapor phase isomerization conditions. Deethylation results in the conversion of the ethyl groups in the ethylbenzene molecule to ethane (in the presence of molecular hydrogen and the hydrogenation function of the deethylation catalyst used in the isomerization zone). Deethylation of ethylbenzene results in the loss of the ethyl substituent bound to the benzene ring. Substantially vapor phase isomerization of xylenes requires heating the hydrocarbons to high temperature in the isomerization zone, followed by cooling and condensation of the isomerization effluent to a liquid state for separation in xylene separator 115, and is therefore expensive. can.

As shown in Figure 5, if streams 123 and 505 can contain significant amounts of ethylbenzene (eg, in the absence of zone 503), in Figure 5 the first isomerization zone 125 can be operated under vapor phase conditions to permeate the deethylation Alkylation converts at least a portion of the ethylbenzene so that the amount of ethylbenzene in the xylene loop is not too high, similar to the conventional process of Figure 1 including an isomerization zone operating under vapor phase conditions. Thus, in one embodiment, zone 503 is absent, zone 507 is present near or partially or completely overlapping zone 125, and zone 125 is operated under vapor phase isomerization conditions.

In embodiments where ethyl-demethylation zone 503 exists, a portion of stream 505 may be recycled (not shown) back to zone 503 to enable high conversion of ethylbenzene in zone 503.

In another embodiment, ethyl-demethylation zone 503 is present, zone 507 is absent, stream 505 is separated to remove light hydrocarbons produced in zone 503 before being supplied to isomerization zone 125, and Zone 125 operates under liquid phase conditions. In such embodiments, stream 505 is depleted of ethylbenzene because a portion of the ethylbenzene in stream 511 is converted to toluene in zone 503 via ethyl-demethylation. Thus, the need for deethylation of ethylbenzene in isomerization zone 125, and thus the need for vapor phase isomerization conditions in zone 205, is reduced. Accordingly, at least a portion, ideally most, and even all of the paraxylene depletion stream 123 may be processed in zone 125 under liquid phase isomerization conditions. Because such liquid phase isomerization is carried out at significantly lower operating temperatures than conventional vapor phase isomerization required in the process of FIG. 1, there is substantial energy savings and a substantial increase in energy efficiency.

Compared to stream 505, first isomerization effluent 127 exiting first isomerization zone 125 is enriched in para-xylene. A portion (shown as stream 127) or all (not shown) of stream 217 is then supplied to a xylene separator in order to recover para-xylene from stream 217. If zone 125 is operated under vapor phase isomerization conditions, stream 217 may contain light and non-aromatic hydrocarbons resulting from deethylation in addition to aromatics such as xylenes and ethylbenzene. Streams 217 and/or 127 may be separated to remove such light and non-aromatic hydrocarbons (not shown) prior to feeding to xylene separator 115. If zone 125 is operated under liquid phase isomerization conditions without deethylating ethylbenzene, stream 217 tends to contain significantly more than the corresponding effluent stream leaving the isomerization zone (if any) under vapor phase conditions Lower amounts of such light and non-aromatic hydrocarbons. Thus, stream 217, or a portion thereof (as shown by stream 127) exiting liquid phase isomerization zone 125, can be supplied directly to xylene separator 115 without intermediate separation steps (optional heating/cooling, etc.). The isomerization of substantially all of the para-xylene depleted stream 123 in the liquid phase isomerization zone alone without the use of a vapor phase isomerization zone clearly results in a comparison of the conventional process of Figure 1 with the need for a vapor phase isomerization zone , a simpler, less energy-consuming, and more energy-efficient xylene circuit.

As shown in FIG. 5 , the first isomerization effluent 127 is split into streams 513 and 515 . After optional further intermediate separation (as the case may be), stream 513, or a portion thereof, is supplied to xylene separator 115. Stream 515, or a portion thereof, may be directed away as a wash stream and used, for example, in a motor gasoline blend, especially if stream 515 contains high concentrations of ethylbenzene. Additionally or alternatively, stream 515 or a portion thereof may be recycled (not shown) to one or more of zones 503 and 507 (if present), and preferably zone 503 (if present), which will contain the Ethylbenzene is further converted via ethyl-demethylation. Additionally or alternatively, stream 515 or a portion thereof may be recycled (not shown) directly to paraxylene recovery subsystem 119 bypassing xylene separator 115 to recover a portion of paraxylene therein. Bypassing the xylene separator can further improve the energy efficiency of the xylene loop. The isomerization effluent from the vapor phase isomerization zone typically contains light hydrocarbons and other non-aromatic hydrocarbons resulting from, for example, dealkylation, and therefore does not have intermediate separation steps (eg, in a deheptanizer and/or xylene separator). 115) is not directly recycled to the p-xylene recovery sub-system. Conversely, the isomerization effluent produced from liquid phase isomerization zone 125 contains much lower concentrations of such light hydrocarbons and other non-aromatic hydrocarbons than typical vapor phase isomerization effluents, if any, and therefore The additional para-xylene formed in the isomerization zone can be recycled directly to the para-xylene recovery subsystem, bypassing the xylene separator. Combining one or both of ethyl-demethylation zones 503 and 507 in liquid phase isomerization zone 125 can completely eliminate the need for a vapor phase isomerization zone in the paraxylene loop, resulting in and as illustrated in Figure 1 An overall higher energy efficiency, and more valuable methylated aromatics yield, is required compared to conventional processes using a vapor phase isomerization zone in the xylene loop. Conversion of a portion of the C2+-hydrocarbyl substituted aromatics to methylated aromatics in zones 503 and/or 507 can be achieved compared to the conventional process of Figure 1 in which at least a portion of the ethylbenzene is dealkylated in the vapor phase isomerization zone, and more more xylene production.

Although the method of Figure 5 does not include the alkyl-demethylation regions at the positions of regions 203, 205, and 209 in the methods of Figures 2 or 3, in certain embodiments it is desirable to additionally provide The alkyl-demethylation zone in one or more of zones 203, 205, and 209 in the method of 2 or 3 gives the method of Figure 5. In such embodiments, high energy efficiency in a xylene loop including liquid phase isomerization, high energy efficiency in a transalkylation process including liquid phase transalkylation, and high xylene production can result . Figure 6: Exemplary inventive transalkylation process

Another aspect of the present disclosure relates to a transalkylation method, an example of which is illustrated in FIG. 6 .

As shown in FIG. 6, similar to FIG. 1, the C9+ aromatics-rich stream 129 rich in C9, C10, and C11+ aromatics compared to the sum stream 114 produced by the xylene separator 115 may contain substantial amounts of methylated aromatics C2+-hydrocarbyl-substituted aromatic hydrocarbons. In Figure 6, stream 129 may first be supplied to an optional alkyl-demethylation zone 603 (if present) containing an alkyl-demethylation catalyst disposed therein. C2+-hydrocarbyl-substituted aromatic hydrocarbons undergo an alkyl-demethylation reaction upon contact with an alkyl-demethylation catalyst and under alkyl-demethylation conditions. Thus, compared to stream 129, the alkyl-demethylation effluent 130 exiting zone 603 is depleted of C2+-hydrocarbyl substituted aromatics and rich in methylated aromatics. The presence of zone 603 enables conversion of some of the C11+C2+-hydrocarbyl substituted aromatics present in stream 129 to useful C9 to C10 aromatics in streams 129 and 133. Without zone 603, most of the C11+C2+-hydrocarbyl substituted aromatics converted in zone 603 would enter stream 135 and be wasted. Conversion of C9+C2+-hydrocarbyl substituted aromatics in zone 603 results in the formation of light hydrocarbons, C8 aromatics, toluene, and optional benzene.

After optional light hydrocarbon removal, stream 130 is then separated in distillation column 131 to obtain C9 to C10 rich aromatics stream 133 (which also contains C6 to C8 aromatics formed in zone 603 (if present)) and C11+ aromatics rich Stream 135. Stream 135 may be directed away and used, for example, as a motor gasoline blend, fuel oil, or the like. The C9 to C10 rich aromatics stream 133 comprises, for example, methylated aromatics (such as trimethylbenzene and tetratoluene), and C2+-hydrocarbyl substituted aromatics (such as ethyltoluene, dihydroindene, ethylxylene, diethylbenzene, tetrahydrobenzene) naphthalene, methylindene, and methyltetrahydronaphthalene). Stream 133 is then supplied to an optional alkyl-demethylation zone 605 containing an alkyl-demethylation catalyst disposed therein. C2+-hydrocarbyl-substituted aromatics undergo an alkyl-demethylation reaction in zone 605 to produce additional amounts of methyl methacrylate while in contact with an alkyl-demethylation catalyst and under alkyl-demethylation conditions Alkylated aromatics and/or benzene. Thus, compared to stream 133, effluent 607 exiting zone 605 is depleted of C2+-hydrocarbyl substituted aromatics and rich in methylated aromatics.

As shown in Figure 6, stream 607 is then supplied to an optional alkyl-demethylation zone 609 containing an alkyl-demethylation catalyst disposed therein. A portion of the residual C2+-hydrocarbyl substituted aromatics in stream 607 is then converted to methylated aromatics and/or in zone 609 under alkyl-demethylation conditions upon contact with the alkyl-demethylation catalyst benzene. Optional zone 609 may be upstream and separate from transalkylation zone 147 (eg, where the alkyl-demethylation catalyst in zone 609 and the transalkylation catalyst in zone 147 are in different tanks, or in a shared tank in different beds). Alternatively, random zone 609 may partially overlap zone 147 (eg, where the alkyl-demethylation catalyst in zone 609 is partially blended with the transalkylation catalyst in zone 147 in a common tank). Alternatively, zones 609 and 147 are the same zone (eg, where the alkyl-demethylation catalyst and the transalkylation catalyst are all blended in a single mixed catalyst bed, or where one catalyst exhibits an alkyl-demethylation catalyst alkylation and transalkylation bifunctional). The alkyl-demethylation effluent from zone 609 can be used directly for transalkylation in transalkylation zone 147.

One or more of alkyl-demethylation regions 603, 605, and 609 are present in the transalkylation methods of the present disclosure.

Toluene-rich stream 146 is also supplied to transalkylation zone 147 . C9+ aromatics are reacted with benzene/toluene in the presence of a transalkylation catalyst and under transalkylation conditions to produce xylenes. Streams 129 and 133 produced from the reconstituted oil stream as illustrated in Figure 1 and/or hydrotreated SCN may contain substantial amounts of C2+-hydrocarbyl substituted aromatics. Direct transalkylation between such C9 to C10 C2+-hydrocarbyl substituted aromatics and benzene/toluene yields ethylbenzene and other C9+C2+-hydrocarbyl substituted aromatics. To increase xylene and/or benzene/toluene production in transalkylation zone 147, typically in the process of Figure 1 the transalkylation catalyst and transalkylation conditions are selected such that in the transalkylation zone At least a portion of the C9 to C10 C2+-hydrocarbyl-substituted aromatics and ethylbenzene are converted to toluene and/or benzene through complete dealkylation of the aromatic rings of the C2+ alkyl group. Dealkylation results in the conversion of C2+ alkyl groups to light hydrocarbons (typically in the presence of molecular hydrogen and the hydrogenation function of the dealkylation catalyst used in the transalkylation zone). Therefore, it is a loss to remove the C2+ alkyl groups in order to make xylenes. The C2+ alkyl group is preferably converted to a methyl group attached to the benzene ring - which can then be used to make xylenes via, for example, isomerization, transalkylation, and/or disproportionation. Similar to the deethylation of ethylbenzene, efficient dealkylation of C9 to C10 C2+-hydrocarbyl substituted aromatics with ethylbenzene in the transalkylation zone typically requires vapor phase conditions that require elevated temperatures. Such vapor phase transalkylation is energy intensive because of the need to cool and condense the vapor effluent of the transalkylation zone to a liquid for distillative separation.

In the inventive process of Figure 5, due to the presence of one or more of zones 603, 605, and 609, and compared to the process of Figure 1, C2+-hydrocarbyl-substituted aromatics entering or present in transalkylation zone 147 The amount is significantly reduced because a significant portion of such C9+C2+-hydrocarbyl substituted aromatics in stream 129 can be converted to methylated aromatics in zones 603, 605, and/or 609. The low concentration of C2+-hydrocarbyl substituted aromatics in the transalkylation zone significantly reduces the need for dealkylation in the transalkylation zone 147. The reduced need for dealkylation enables transalkylation to be accomplished in zone 147 at significantly lower temperatures than conventional vapor phase transalkylation processes requiring dealkylation such that some or even all of it is present in zone 147 The aromatics in 147 are in the liquid phase. Such partial liquid phase or full liquid phase transalkylation can result in substantial energy savings and a substantial increase in energy efficiency compared to conventional full vapor phase transalkylation required for dealkylation. The conversion of a portion of the C2+-hydrocarbyl substituted aromatics to methylated aromatics in zones 603, 605, and/or 609 can also be accomplished and the diagram of dealkylation of at least a portion of the C2+-hydrocarbyl substituted aromatics in the transalkylation zone 1. Compared with the traditional method, more xylene yields. In the conventional process of Figure 1 in the absence of zone 603, the C11+C2+-hydrocarbyl substituted aromatic hydrocarbons present in stream 129 leave separation column 131 in stream 135 and thus will not be used for transalkylation to produce xylenes . In an embodiment of the transalkylation process of the present disclosure that includes zone 603, as discussed above, a portion of the C11+C2+-hydrocarbyl-substituted arene alkyls present in stream 129 is demethylated to produce C10- Aromatics, which exit separation column 131 in stream 133, can finally be converted to useful xylene and/or benzene products via random zones 605 and 609 and finally transalkylation zone 147. Thus, the presently disclosed transalkylation process including alkyl-demethylation zone 603 is highly advantageous if streams 113, 114, and/or 129 contain substantial amounts of C11+C2+-hydrocarbyl-substituted aromatics , as more methylated aromatics such as xylene and/or benzene can be produced.

In traditional transalkylation processes involving dealkylation of C2+-hydrocarbyl substituted aromatics, a portion of the C2+ alkyl and/or aliphatic rings fused to the aromatic ring is converted to light hydrocarbons, and due to the aromatic ring Loss of non-aromatic hydrocarbons may be produced. Therefore, it may be necessary to separate the transalkylation effluent to remove such light and non-aromatic hydrocarbons (eg, through a deheptanizer, in Figure 1) before feeding it to an aromatics separation column (eg, benzene column 141 in Figure 1). not shown). In the embodiment of the process of the invention of Figure 6, the opposite is true because the small amount of C2+-hydrocarbyl substituted aromatics in stream 607 and/or transalkylation zone 147 dealkylates the C2+-hydrocarbyl substituted aromatics Minimized or eliminated, transalkylation effluent 149 contains light hydrocarbons with such small amounts of non-aromatic hydrocarbons, if any, that effluent 149 can be supplied directly to benzene column 141 to remove light hydrocarbons without an intermediate separation step With non-aromatic hydrocarbons (with optional heating/cooling etc., as appropriate). Thus, the presence of one or more alkyl-demethylation zones 603, 605, and 609 in the process of Figure 6 enables simpler transalkanes that require less equipment and steps and also provide substantial energy savings and greatly improved energy efficiency base method. Stream 149 in Figure 6 may contain, for example, benzene, toluene, xylenes, mesitylenes, tetratoluenes, and desirably small amounts of C8, C9, C10, and C11+C2+-hydrocarbyl substituted aromatic hydrocarbons.

In certain embodiments, > 50 wt%, or > 60 wt %, or > 70 wt %, or > 80 wt %, or > 90 wt %, or > 95 wt %, or > 98 wt % of stream 607 are methylated aromatic hydrocarbons. Thus, most of the reactions in transalkylation zone 147 may be the exchange of methyl groups between aromatics (such as benzene, toluene, trimethylbenzene, and tetratoluene), resulting in a net production of xylenes and C9 to C10 methylated aromatics, and benzene and/or toluene consumption. Preferably, such transalkylation is carried out in the liquid phase, wherein (i) the C8 aromatics present in the transalkylation zone are substantially liquid phase; and/or (ii) are present in the transalkylation Aromatics (including benzene) in the zone are in a substantially liquid phase. Transalkylation effluent 149 may contain benzene, toluene, xylenes, C9+ methylated aromatics, and minor amounts of C8+C2+-hydrocarbyl substituted aromatics.

As shown in Figure 6, stream 149 is then supplied to benzene column 141 (along with other streams, such as stream 139) to separate aromatics contained therein to obtain benzene product stream 143, toluene-rich and/or benzene-rich toluene-rich stream 146 (which is partially or fully fed to transalkylation zone 147), and C8+ aromatics-rich stream 145 (comprising xylenes, C9+ methylated aromatics, and preferably small amounts of C8+C2+-hydrocarbyl-substituted aromatics), It is supplied to the xylene separator 115, as described above.

The following non-limiting examples are provided to further illustrate the present disclosure. [Example] Part A: Manufacture of Alkyl-Demethylation Catalysts

The alumina support system used to prepare the catalyst was purchased from Sasol (SBa-200, gamma-phase alumina). Catalysts A1, A2, A3, A4, A5, and A6 were prepared using the following method: The alumina support was pre-calcined at 500°C in air for 6 hours. Rh metal was added to the support by incipient wetness impregnation (IWI) with an aqueous solution of rhodium (III) nitrate from BASF. Rhodium(III) nitrate solution was added to the initial wet impregnation point of each support (0.5 to 1.0 g solution/g support) to give the specified metal content. The samples were then dried at 120°C for 16 hours and then calcined in air at 600°C for 6 hours. Catalyst A7 was prepared using a method similar to that described above, except that the alumina support was treated with 3 to 5 molar % aqueous lanthanum (III) nitrate to add La to the alumina prior to pre-calcination at 500°C for 6 hours in air. Alumina support body. Catalyst A8 was prepared similarly to Catalyst A7, except that after treatment of the alumina support with a 3 to 5 molar % aqueous solution of lanthanum (III) nitrate, the alumina support was subjected to pre-calcination at 1200°C in air 8 hours to convert gamma-phase alumina to theta-phase alumina. It is hypothesized that La doped in alumina can help stabilize and promote the desired θ phase formation to achieve optimal physical and chemical properties. The La dopant is believed to be present in octahedral vacancies within the alumina lattice, thus stabilizing the alumina and preventing undesired loss of pore volume and surface area due to high temperature treatment at 1200°C. The compositions of catalysts A1 to A8 are listed below, wherein the Rh concentration is expressed as the percentage of Rh based on the total weight of the catalyst composition: A1 Rh(0.1%)/Alumina(γ) A2 Rh(0.7%)/Alumina(γ) A3 Rh(0.9%)/Alumina(γ) A4 Rh(1.8%)/Alumina(γ) A5 Rh(2.0%)/Alumina(γ) A6 Rh(3.5%)/Alumina(γ) A7 Rh(3.5%)/La-alumina(γ) A8 Rh(3.5%)/La-alumina (θ) Part B: Process for Making Para-Xylene In these examples, "C2-A" refers to aromatic hydrocarbons comprising an ethyl group attached to a benzene ring; "C2-A conversion" refers to deethylation as described above and/or ethyl-demethylation to convert aromatics containing an ethyl group attached to a benzene ring; "C3-A" refers to aromatics containing a C3 alkyl group attached to a benzene ring; "C3-alkyl- Aromatic conversion" refers to the conversion of aromatics comprising C3 alkyl groups attached to the benzene ring by dealkylation and/or alkyl-demethylation as described above. TMZ means trimethylbenzene. Example B1 (comparative): Traditional method of Figure 1 in the absence of any alkyl-demethylation regions

A simulation of the process for the production of para-xylene from naphtha of Figure 1 in the absence of any alkyl-demethylation regions was performed. Significant amounts of C2+-hydrocarbyl substituted aromatics are present in streams 107, 113, 114, 117, and 123, 129, 123. The process utilizes a vapor phase isomerization zone to process 50 wt% of the paraxylene depleted stream 123 and a liquid phase isomerization zone running in parallel with the vapor phase isomerization zone to process the remaining 50 wt%. The ethylbenzene in stream 123 supplied to vapor phase isomerization zone 123 undergoes deethylation therein. Additionally, the process utilizes a vapor phase inversion alkylation zone to process stream 133 (heavy aromatics) along with stream 146 (toluene) to produce mixed xylenes and benzene. The C9+C2+-hydrocarbyl substituted aromatics in stream 133 supplied to the vapor phase transalkylation zone are subjected to dealkylation therein. Method assumptions and simulation results are reported in Table I below. Example B2 (Inventive): Inventive Process of Figure 2 in the Presence of Alkyl-Demethylation Zone 209

A simulation of the process for the production of para-xylene from a naphtha process of Figure 2 was performed, except that stream 145 was fed directly to xylene separator 115 rather than to alkyl-demethylation zone 209, where Alkyl-demethylation zones 203 and 205 are absent, and alkyl-demethylation zone 209 is present. In this example B2, the amount of stream 113 and its composition are the same as in Example B1 above. In the method of this example B2, in zone 209, a portion of ethylbenzene and C9+C2+-hydrocarbyl-substituted aromatics are converted into toluene, xylenes, mesitylenes, and other methylated aromatics. Thus, xylene stream 117 and para-xylene depleted stream 123 in FIG. 2 contain a reduced concentration of ethylbenzene compared to their corresponding streams in FIG. 1 . At sufficiently high ethylbenzene conversion in zone 209, vapor phase isomerization of stream 123 and deethylation of ethylbenzene therein becomes unnecessary. Therefore, in this example, all of stream 123 is fed to liquid phase isomerization zone 125. In turn, the entirety of the isomerization effluent 217 is supplied to the xylene separator 115 . Optionally, the purge stream 213 can be recycled back to zone 209. In addition, C9+ stream 129 and produced stream 133 in Figure 2 contain reduced concentrations of C9+C2+-hydrocarbyl substituted aromatics compared to their corresponding streams in Figure 1 . Vapor phase transalkylation in zone 147 affects the dealkylation of any remaining C9+C2+-hydrocarbyl substituted aromatics. Although not assumed in this example, it is speculated that the vapor phase transalkylation of stream 144 combined with the dealkylation of C9+C2+-hydrocarbyl substituted aromatics therein may become unnecessary using liquid phase transalkylation zone 147 Or replace vapor phase transalkylation zone 147. Additional methodological assumptions and simulation results are reported in Table I below. Example B3 (comparative): Modified method of Example B2 above, wherein region 209 is replaced by a dealkylation region

The method simulated in this Example B3 differs from that simulated in Example B2 only in that the alkyl-demethylation region 209 is replaced at the same position with a dealkylation region. Therefore, in this example B3, in zone 209, a portion of ethylbenzene and C9+C2+-hydrocarbyl-substituted aromatics are converted to benzene and toluene. Thus, in this example xylene stream 117 and para-xylene depleted stream 123 contain a reduced concentration of ethylbenzene compared to their corresponding streams in FIG. 1 . Deethylation and vapor phase isomerization of stream 123 becomes unnecessary. Thus, in this Example B3, similar to Example B2, all of stream 123 is fed to liquid phase isomerization zone 125. Similar to Example B2, in this Example B3, the isomerization effluent 217 was further supplied to the xylene separator 115 in its entirety. Additional methodological assumptions and simulation results are reported in Table I below. Table I Example B1 B2 B3 Yield assumptions in District 209 Ethyl conversion rate (%) n/a 90 85 C3-alkyl conversion rate (%) n/a 100 100 methyl conversion n/a 3 0 Method Assumptions in District 209 Stream 213 recirculated to zone 209 (% of stream 123) n/a 4 4 performance Nominal paraxylene production (KTA) 1 1.09 1 Paraxylene/Feed (wt%) 57 62 57 Benzene/Feed (wt%) 20 16 20 (para-xylene + benzene)/feed (wt%) 77 78 77 (Liquid product)/Feed (wt%) 94 96 94

The data in Table I clearly show that the inventive method of Example B2 is superior to the methods of Comparative Examples B1 and B3. Regarding nominal para-xylene production, for every 1 kiloton per year ("KTA") produced in Examples B1 and B3, the process of the invention in Example B2 is produced from the same amount of feed having the same composition 1.09 KTA of paraxylene, which represents a 9% increase. The increase in para-xylene production is partly achieved by a reduction in benzene production. In the inventive process of Example B2, the total weight percent of para-xylene and benzene relative to the feed, and the total weight percent of liquid product relative to the feed were increased. Accordingly, the overall percentage in the inventive process of Example B2 is reduced compared to the overall percentage of typically low value gaseous products in Examples B1 and B3. These data clearly demonstrate the advantages and higher economic value of the alkyl-demethylation zone than using dealkylation either before the xylene loop or in the vapor phase isomerization step in the xylene loop. Examples B4 to B7: Ethyl-demethylation of ethylbenzene based on isomerization

In these examples, a feed comprising 87 wt% xylene and 13 wt% ethylbenzene (simulating para-xylene depletion stream 123 in Figure 5) was combined with an ethyl-demethylation catalyst at ethyl-demethylation contact in the methylation reactor 503. The composition of the ethyl-demethylation reactor effluent was analyzed. The catalysts prepared in Examples A1, A3, A4 and A6 were tested in these examples. Method conditions and test results are reported in Table II below.

The data in Table II show that the alkyl-demethylation catalysts and processes in Examples B4 to B7 achieve significantly higher conversions of ethylbenzene (desirable) than xylenes (undesired). High product selectivity to toluene (the desired product) is achieved and further demethylation of toluene to benzene and loss of aromatic rings is minimized. Therefore, the catalysts and process conditions in these Examples B4 to B7 can be used in the ethyl-demethylation zones 503 and/or 507 in the process of FIG. 5 .

This is in contrast to what is disclosed in US Patent No. 4,331,825, in which large conversions of xylenes (undesirable) and high selectivity to methane (undesirable) were observed. Example B8: Alkyl-Demethylation of Transalkylation Feeds Containing C9+C2+- Hydrocarbyl-Substituted Aromatics

In this example, a feed mixture (transalkylation) comprising about 80% C9+ aromatics (representative of feed 133 in the process of Figure 6) and 20% toluene (representative of feed 146 in the process of Figure 6) was A representative of the feed to the zone) was fed to the alkyl-demethylation reactor (zone 605 in Figure 6) to contact the alkyl-demethylation catalyst prepared in Example A6 above. Process conditions included: temperature in the range from 380 to 405°C, pressure of 103 psig, WHSV: in the range from 2.5 to 20 hours ^-1 , and _H2 /hydrocarbon mole ratio in the range from 2 to 6. Process conditions were varied during the experiments to achieve varying degrees of conversion of the C9+ aromatic components. The composition of the effluent from the reactor was analyzed. Some of the test conditions and results are reported in Table III below. We found the presence of methane in the effluent, but the absence of ethane and propane, indicating that the conversion of ethyl-aromatics to C3-alkyl-aromatics is by alkyl-demethylation rather than dealkylation .

The data in Table III show that the conversion of ethyl-aromatics to propyl-aromatics (desired) by the alkyl-demethylation catalyst and method in Example B8 is significantly higher than that of trimethylbenzene (undesired). ) conversion rate. Thus, the catalysts and process conditions of this example can be used in the alkyl-demethylation zones 603, 605, and/or 609 in the process of FIG. 6 . Examples B9 to B10: Alkyl-Demethylation of C9+C2+-hydrocarbyl-Substituted Aromatic Transalkylation Feeds

The same steps as in Example B8 were carried out in these examples, except that the alkyl-de-alkylation used in Example B8 was replaced in Examples B9 and B10 with the catalysts prepared in Examples A7 and A8, respectively. methylation catalyst. In Examples B9 to B10, similar to Example B8, the conversion of ethyl-aromatics and conversion of C3-alkyl-aromatics was observed to be significantly higher than the conversion of trimethylbenzene. Test results for some of the Examples B9 and B10 are also reported in Table III below. We found the presence of methane in the effluent, but the absence of ethane and propane, indicating that the conversion of ethyl-aromatics to C3-alkyl-aromatics is by alkyl-demethylation rather than dealkylation .

The present disclosure may additionally include the following non-limiting examples:

A1. A method of manufacturing xylene, the method comprising: (I) providing a C6+ aromatic hydrocarbon-containing stream comprising C2+-hydrocarbyl-substituted aromatic hydrocarbons, wherein the C2+-hydrocarbyl-substituted aromatic hydrocarbon has (i) a C2+ alkyl substituent attached to an aromatic ring therein and/or (ii) ) an aliphatic ring fused to an aromatic ring therein; (II) optionally contacting the C6+ aromatics-containing stream with a first alkyl-demethylation catalyst in a first alkyl-demethylation zone under a first set of alkyl-demethylation conditions to converting at least a portion of the C2+-hydrocarbyl-substituted aromatics to alkyl-demethylated aromatics to obtain an optional first alkyl-demethylation effluent leaving the first alkyl-demethylation zone; (III) Separating at least a portion of the C6+ aromatics-containing stream and/or the first alkyl-demethylation effluent in a first separation unit to obtain a C6 to C7 hydrocarbon-rich stream and a first C8+ aromatics-rich stream ; (IV) The first C8+ aromatics stream is optionally combined with a second alkyl-demethylation catalyst in a second alkyl-demethylation zone under a second set of alkyl-demethylation conditions contacting to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if contained in the first C8+ aromatics-rich stream) to alkyl-demethylated aromatics to obtain exiting the second alkyl-demethylated aromatics Optional second alkyl-demethylation effluent from the chemistry zone; (v) separating at least a portion of the first C8+ aromatics-rich stream and/or the second alkyl-demethylation effluent in a second separation unit to obtain a xylene-rich stream and a C9+ aromatics-rich stream; and (VI) optionally separating the xylene-rich stream in the first paraxylene recovery sub-system to obtain a first paraxylene product stream and a first paraxylene depleted stream; wherein at least one of steps (II) and (IV) is performed.

A2. The method of A1, wherein: The C2+-hydrocarbyl-substituted aromatic hydrocarbons include ethylbenzene, ethyltoluene, n-propylbenzene, cumene, diethylbenzene, n-propyltoluene, cumene, ethylxylene, n-butylbenzene, secondary butylbenzene , Isobutylbenzene, tertiary butylbenzene, dihydroindene, indene, methyldihydroindene, tetrahydronaphthalene, and mixtures thereof.

A3. The method of A1 or A2, wherein the C2+-hydrocarbyl-substituted aromatics have a total concentration in the range of 2 to 70% by weight based on the total weight of the C6+ aromatics contained in the C6+ aromatics-containing stream.

A4. The method of A2 or A3, wherein the C2+-hydrocarbyl-substituted aromatics comprise ethylbenzene at a concentration in the range of 2% to 50% by weight based on the total weight of the C8 aromatics contained in the C6+ aromatics-containing stream .

A5. The method of any one of A2 to A4, wherein the C2+-hydrocarbyl-substituted aromatics comprises its C9 aromatics moiety, and the C9 aromatics moiety has the C9 aromatics total weight contained in the C6+ aromatics stream as a benchmark The total concentration is in the range of 30 to 90% by weight.

A6. The method of any one of A1 to A5, wherein step (VI) is carried out, and the method additionally comprises: (VII) Combining at least a portion of the first paraxylene depleted stream with a third alkyl-demethylation catalyst in a third alkyl-demethylation zone in a third set of alkyl-demethylation optionally contacted under stoichiometric conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if contained in the first para-xylene depleted stream) to alkyl-demethylated aromatics to obtain exiting the first para-xylene depleted stream. The optional third alkyl-demethylation effluent of the trialkyl-demethylation zone; (VIII) combining at least a portion of the first paraxylene depletion stream and/or at least a portion of the third alkyl-demethylation effluent with an isomerization catalyst in a first isomerization zone contacting under structuring conditions to produce a first isomerization effluent exiting the first isomerization zone comprising a higher concentration of paraxylene than the first paraxylene depletion stream; and (IX) Separating at least a portion of the first isomerization effluent in a second paraxylene recovery subsystem to obtain a second paraxylene product stream and a second paraxylene depletion stream.

A7. The method of A6, wherein step (VII) is performed and the first isomerization zone is downstream of the third alkyl-demethylation zone.

A8. The method of A7, which additionally includes: (VIIIa) combining at least a portion of the first paraxylene depletion stream and/or at least a portion of the third alkyl-demethylation effluent with a fourth alkyl-demethylation catalyst in the first Contact in the isomerization zone under a fourth set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if in the first paraxylene depletion stream and/or the third alkane alkyl-demethylation effluent) into alkyl-demethylated aromatics.

A9. The method of A6, wherein the first isomerization zone at least partially overlaps the third alkyl-demethylation zone.

A10. The method of A6, wherein the second para-xylene recovery sub-system is the first para-xylene recovery sub-system, the first and second para-xylene product streams are part of a combined stream, and the first and The second paraxylene depletion stream is part of the combined stream.

A11. The method of any one of A6 to A10, wherein liquid phase isomerization is carried out in the first isomerization zone.

A12. The method of A11, wherein in step (VIII) substantially all of the third alkyl-demethylation effluent is fed to the first isomerization zone.

A13. The method of any one of A6 to A10, wherein the isomerization conditions comprise maintaining xylene in a substantially vapor phase in the first isomerization zone.

A14. The method of A13, wherein in step (VIII) a first portion of the paraxylene depleted stream or a portion of the third alkyl-methylation effluent is fed to the first isomerization zone, and the The method additionally contains: (VIIIb) Combining the second portion of the third alkyl-methylation effluent with the second isomerization catalyst in the second isomerization zone under a second set of isomerization conditions sufficient to effect vapor phase isomerization contacting down to produce a second isomerization effluent; and (VIIIc) Separating at least a portion of the second isomerization effluent in a second paraxylene recovery subsystem to obtain a second paraxylene product stream and a second paraxylene depletion stream.

A15. The method of any one of A1 to A14, further comprising: (X) Optionally combining at least a portion of this C9+ rich aromatics stream with a fifth alkyl-demethylation catalyst in a fifth alkyl-demethylation zone under a fifth set of alkyl-demethylation conditions contacting to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if contained in the C9+ aromatics-rich stream) into alkyl-demethylated hydrocarbons to produce exiting the fifth alkyl-demethylation the fifth alkyl-demethylation effluent of the zone; (XI) optionally separating the C9+ aromatics stream and/or the fifth alkyl-demethylation effluent in a third separation unit to obtain a C9 to C10 aromatics stream and a C11+ aromatics stream; (XII) combining at least a portion of the C9+ aromatics stream, and/or at least a portion of the fifth alkyl-demethylation effluent, and/or at least a portion of the C9 to C10 rich aromatics stream with a sixth alkyl- The demethylation catalyst is optionally contacted in the sixth alkyl-demethylation zone under a sixth set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatic hydrocarbons (if in the The C9+ aromatics stream, and/or the fifth alkyl-demethylation effluent, and/or contained in the C9 to C10 rich aromatics stream) are converted into alkyl-demethylated hydrocarbons to produce the the sixth alkyl-demethylation effluent of the sixth alkyl-demethylation zone; (XIII) converting at least a portion of the C9+ aromatics-rich stream, and/or at least a portion of the fifth alkyl-demethylation effluent, and/or at least a portion of the C9- to C10-rich aromatics stream, and/or at least a A portion of this sixth alkyl-demethylation effluent, and optionally a benzene/toluene stream, is fed to the transalkylation zone; (XIV) contacting C9+ aromatics with benzene/toluene in the presence of a transalkylation catalyst under transalkylation conditions to produce a transalkylation effluent leaving the transalkylation zone; and (XV) Separating the transalkylation effluent in a fourth separation unit to obtain an optional first benzene product stream, a toluene-rich stream, and a second C8+ aromatics-rich stream.

A16. The method of A15, which additionally includes: (XVI) Feeding the second C8+ aromatics stream together with the first C8+ aromatics stream to the second separation unit.

A17. A method as in A15 or A16, which additionally comprises: (XVII) Feeding at least a portion of the first benzene product stream and/or at least a portion of the toluene-rich stream to the transalkylation zone as at least a portion of the benzene/toluene stream.

A18. The method of any one of A15 to a17, wherein the sixth alkyl-demethylation zone is upstream of the transalkylation zone.

A19. The method of any one of A15 to A17, wherein the sixth alkyl-demethylation zone at least partially overlaps the transalkylation zone.

A20. The method of any one of A1 to A19, further comprising: (XVIII) obtaining a first C6 to C7 rich aromatics stream from the C6 to C7 rich hydrocarbon stream; and (XIX) Separating the first C6- to C7-enriched aromatics stream in a fifth separation unit to obtain a second benzene product stream, and a second toluene-enriched stream.

A21. The method of A20, wherein the fifth separation device is the fourth separation device, the first and the second benzene product streams are combined streams, and the first and second toluene-rich streams are combined streams.

A22. The method of any one of A15 to A21, further comprising: (XX) contacting at least a portion of the first toluene-enriched stream and/or at least a portion of the second toluene-enriched stream with a disproportionation catalyst in a disproportionation zone under disproportionation conditions to produce para-xylene-containing paraxylene exiting the disproportionation zone disproportionation effluent; (XXI) separating at least a portion of the disproportionated effluent in a sixth separation unit to obtain a third para-xylene-rich stream and a third toluene-rich stream; and (XXII) Optionally recycling at least a portion of the third toluene-rich stream to the disproportionation zone.

A23. The method of any one of A15 to A21, wherein the sixth separation device and/or the fifth separation device and/or the fourth separation device are the same device, the third p-xylene-rich stream, and/ or the first C8+ aromatics-rich stream, and/or the second C8+ aromatics-rich stream are part of the combined stream, and the first toluene-rich stream, and/or the second toluene-rich stream, and/or the third toluene-rich stream is part of the combined stream.

A24. The method of A22, which additionally comprises: (XXIII) Separating the third paraxylene rich stream in a third paraxylene recovery sub-system to obtain a third paraxylene product stream and a third paraxylene depleted stream.

A25. The method of any one of A15 to A24, further comprising: (XXIV) combining at least a portion of the first benzene product stream, and/or at least a portion of the second benzene product stream, and/or at least a portion of the first toluene-rich stream, and/or at least a portion of the second rich stream The toluene stream, and/or at least a portion of this third toluene-rich stream, is contacted with methanol and/or dimethyl ether in the presence of an alkylation catalyst in an alkylation zone under alkylation conditions to produce the alkane leaving the an alkylation effluent of the alkylation zone comprising para-xylene; (XXV) separating at least a portion of the alkylation effluent to obtain a fourth para-xylene-rich stream and a fourth toluene-rich stream; and (XXVI) Separating the fourth paraxylene rich stream in a fourth paraxylene recovery sub-system to obtain a fourth paraxylene product stream and a fourth paraxylene depleted stream.

A26. The method of A23 or A24, wherein the third and fourth para-xylene recovery sub-systems are the same sub-system, and the third and fourth para-xylene product streams are part of a combined stream.

A27. The method of A24 or A25, wherein the third paraxylene recovery sub-system and/or the fourth paraxylene recovery system comprises a crystallizer.

A28. The method of any one of A1 to A27, wherein step (1) comprises: (Ia) providing heavy petroleum encephalitis; (Ib) contacting the heavy petroleum naphtha stream with a recombination catalyst under recombination conditions in a recombination zone to obtain a recombination effluent containing C6+ aromatics leaving the recombination zone, wherein at least a portion of the recombination effluent is produced in this step (Ib) C2+-hydrocarbyl-substituted aromatic hydrocarbons; and (Ic) providing at least a portion of the reformed effluent as at least a portion of the C6+ aromatics-containing stream.

A29. The method of A28, which additionally comprises: (Id) contacting the heavy petroleum naphtha stream and/or the intermediate reaction mixture with a seventh alkyl-demethylation catalyst in a recombination zone under a seventh set of alkyl-demethylation conditions to convert at least a portion of the The C2+-hydrocarbyl-substituted aromatics are converted to alkyl-demethylated aromatics.

A30. The method of A28 or A29, wherein the first alkyl-demethylation zone is downstream of the recombination zone and/or the seventh alkyl-demethylation zone.

A31. The method of A28 or A29, wherein the first alkyl-demethylation region at least partially overlaps the recombination region and/or the seventh alkyl-demethylation region.

A32. The method of any one of A1 to A31, wherein at least a portion of the first C6+ aromatics-containing stream is derived from a hydrotreated steam cracked petroleum naphtha.

A33. The method of A32, wherein the C5-rich hydrocarbon stream is obtained in step (III).

A34. The method of any one of A1 to A33, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane Alkyl-demethylation catalyst, and/or the fourth alkyl-demethylation catalyst, and/or the fifth alkyl-demethylation catalyst, and/or the sixth alkyl- The demethylation catalyst, and/or the seventh alkyl-demethylation catalyst, identically or differently comprise a first metal element selected from the group consisting of Groups 7, 8, 9, and 10 metals and combinations thereof, and supports.

A35. The method of A34, wherein the first metal element is selected from the group consisting of Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and combinations thereof.

A36. The method of A34 or A35, wherein in each alkyl-demethylation catalyst, the concentration of the first metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

A37. The method of any one of A34 to A36, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane Alkyl-demethylation catalyst, and/or the fourth alkyl-demethylation catalyst, and/or the fifth alkyl-demethylation catalyst, and/or the sixth alkyl- The demethylation catalyst, and/or the seventh alkyl-demethylation catalyst, identically or differently, additionally comprises a second metal element selected from the group consisting of Groups 11, 12, 13, and 14 metals and combinations thereof .

A38. The method of A37, wherein the second metal element is selected from: Group 11, 12, 13, and Group 14 elements, such as Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations thereof.

A39. The method of A37 or A38, wherein in each alkyl-demethylation catalyst, the concentration of the second metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

A40. The method of any one of A34 to A39, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane Alkyl-demethylation catalyst, and/or the fourth alkyl-demethylation catalyst, and/or the fifth alkyl-demethylation catalyst, and/or the sixth alkyl- The demethylation catalyst, and/or the seventh alkyl-demethylation catalyst, identically or differently, additionally comprises a third metal element selected from the group 1 and 2 metals and combinations thereof.

A41. The method of A40, wherein the third metal element is selected from the group consisting of: Li, N, K, Rb, Cs, Mg, Ca, Ba, and combinations thereof.

A42. The method of A40 or A41, wherein in each alkyl-demethylation catalyst, the concentration of the third metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

A43. The method of any one of A34 to A42, wherein at least one of each of the first, second, third, fourth, fifth, sixth, and seventh alkyl-demethylation catalysts comprises Molecular sieves, preferably zeolites, serve as at least a portion of the support.

A44. The method of any one of A1 to A43, wherein the first, second, third, fourth, fifth, sixth, and seventh groups of alkyl-demethylation conditions are identically or differently comprising at least one of the following: a temperature in the range from 200 to 500°C; an absolute pressure in the range from 350 to 2500 kPa; the molar ratio of molecular hydrogen to hydrocarbon in the range from 0.5 to 20; Liquid weight hourly space velocity in the range 1 to 20 hours ^-1 .

B1. A C8 aromatic hydrocarbon isomerization method, the method comprises: (i) providing a first C8 aromatics stream comprising ethylbenzene, para-xylene, meta-xylene, and optionally ortho-xylene; (ii) separating the first C8 aromatics stream in a para-xylene recovery subsystem to obtain a para-xylene product stream and a para-xylene depletion stream; (iii) contacting at least a portion of the para-xylene depleted stream with a first ethyl-demethylation catalyst in a first ethyl-demethylation zone to remove at least a portion of the para-xylene present in the para-xylene converting ethylbenzene in the depletion stream to toluene to obtain a first ethyl-demethylation effluent leaving the first ethyl-demethylation zone; (iv) isomerizing at least a portion of the para-xylene depleted stream and/or at least a portion of the first ethyl-demethylation effluent with a first xylene isomerization catalyst in a first xylene contacting in the zone under a first set of xylene isomerization conditions to obtain a first xylene isomerization effluent; and (v) supplying at least a portion of the first xylene isomerization effluent to a para-xylene recovery subsystem to obtain the para-xylene product stream and the para-xylene depletion stream.

B2. The C8 aromatics isomerization process of B1, wherein the first xylene isomerization zone is downstream of the first ethyl-demethylation zone.

B2a. The C8 aromatics isomerization process of B2, further comprising: (iva) combining at least a portion of the para-xylene depleted stream and/or at least a portion of the first ethyl-demethylation effluent with the first The diethyl-demethylation catalyst is contacted in the first xylene isomerization zone under a second set of ethyl-demethylation conditions to remove at least a portion of the catalyst present in the first isomerization zone of ethylbenzene is converted into toluene.

B3. The C8 aromatics isomerization process of B1, wherein the first xylene isomerization zone at least partially overlaps the first ethyl-demethylation zone.

B4. The C8 aromatics isomerization method according to any one of B1 to B3, wherein the liquid phase isomerization is carried out in the first xylene isomerization zone.

B5. The C8 aromatics isomerization process of B4, wherein substantially all of the first ethyl-demethylation effluent is fed to the first xylene isomerization zone.

B6. The C8 aromatics isomerization process of B4 or B5, wherein the first set of xylene isomerization conditions comprises the absence of molecular hydrogen co-feed to the first isomerization zone.

B7. The C8 aromatics isomerization process of any one of B1 to B3, wherein vapor phase isomerization is performed in the first xylene isomerization zone.

B8. The C8 aromatic hydrocarbon isomerization method of B7, wherein the first A portion of the first ethyl-demethylation effluent is fed to the first xylene isomerization zone, and the process additionally comprises: (vi) a second portion of the first ethyl-demethylation The alkylation effluent is contacted with a second xylene isomerization catalyst in a second xylene isomerization zone under a second set of xylene isomerization conditions to produce a second xylene isomerization effluent in which liquid Phase isomerization is performed in the second xylene isomerization zone; (vii) at least a portion of the second xylene isomerization effluent is separated in a paraxylene recovery subsystem to obtain paraxylene Product stream and para-xylene depletion stream.

B9. The C8 aromatics isomerization process of any one of B1 to B8, further comprising: (viii) directing a portion of the paraxylene depleted stream as a first wash stream.

B10. The C8 aromatics isomerization process of any one of B1 to B7, further comprising: (ix) conducting a part of the first isomerization effluent and/or a part of the second isomerization effluent Walk as a second wash stream.

B11. The method of any one of B1 to B10, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst identically or differently comprise a catalyst selected from the group consisting of The first metal element of Groups 7, 8, 9, and 10 metals and combinations thereof, and supports.

B12. The method of B11, wherein the first metal element is selected from the group consisting of Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and combinations thereof.

B13. The method of B12 or B13, wherein in each ethyl-demethylation catalyst, the concentration of the first metal element is based on the total weight of each ethyl-demethylation catalyst at 0.1 to within 10% by weight.

B14. The method of any one of B11 to B13, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst, identically or differently, additionally comprise selected from the group consisting of The second metal element of Group 11, 12, 13, and 14 metals and combinations thereof.

B15. The method of B14, wherein the second metal element is selected from group 11, 12, 13, and 14 elements, such as Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations thereof.

B16. The method of B14 or B15, wherein in each ethyl-demethylation catalyst, the concentration of the second metal element is based on the total weight of each ethyl-demethylation catalyst at 0.1 to within 10% by weight.

B17. The method of any one of B11 to B16, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst, identically or differently, additionally comprise selected from the group consisting of The third metal element of Group 1 and 2 metals and compositions thereof.

B18. The method of B17, wherein the third metal element is selected from the group consisting of: Li, N, K, Rb, Cs, Mg, Ca, Ba, and combinations thereof.

B19. The method of B17 or B18, wherein in each ethyl-demethylation catalyst, the concentration of the third metal element is based on the total weight of each ethyl-demethylation catalyst at 0.1 to within 10% by weight.

B20. The method of any one of B1 to B19, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst identically or differently comprise molecular sieves (preferably zeolite) as at least a part of the support.

B21. The method of any one of B1 to B19, wherein the first and second sets of alkyl-demethylation conditions identically or differently comprise at least one of the following: a temperature in the range from 200 to 500°C ; absolute pressure in the range from 350 to 2500 kPa; molar ratio of molecular hydrogen to hydrocarbon in the range from 0.5 to 20; and liquid weight hourly space velocity in the range from 1 to 20 h ^-1 .

B22. A method for converting C8 aromatics, the method comprising: (i) providing a first C8 aromatics stream comprising ethylbenzene, p-xylene, m-xylene, and optional o-xylene; (ii) recovering at p-xylene separating the first C8 aromatics stream in a secondary system to obtain a paraxylene product stream and a paraxylene depletion stream; (iii) separating at least a portion of the paraxylene depletion stream from the first ethyl-demethylation The alkylation catalyst is contacted in the first ethyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the ethylbenzene present in the para-xylene depleted stream into toluene to obtain the first ethyl-demethylation effluent leaving the first ethyl-demethylation zone; (iv) combining at least a portion of the first ethyl-demethylation effluent with optional At least a portion of this para-xylene depleted stream is contacted with a first xylene isomerization catalyst in a first xylene isomerization zone under a first set of xylene isomerization conditions to obtain a first xylene isoform and (v) supplying at least a portion of the first xylene isomerization effluent to a para-xylene recovery subsystem to obtain a para-xylene product stream and a para-xylene depletion stream; wherein: the The first group of ethyl-demethylation conditions includes: temperatures in the range from 200 to 500°C; absolute pressures in the range from 350 to 2500 kPa; molecular hydrogen to hydrocarbons in the range from 0.5 to 20 and the liquid weight hourly space velocity in the range from 1 to 20 hours ^-1 ; and the first ethyl-demethylation catalyst comprises a metal selected from the group consisting of Groups 7, 8, 9, and 10 and their The first metal element of the composition, and the support.

C1. A method of transalkylation comprising: (A) providing a C9+ arene stream comprising C2+-hydrocarbyl-substituted arenes, wherein the C2+-hydrocarbyl-substituted arenes have (i) a C2+ alkyl substituent attached to an aromatic ring therein and/or (ii) Aliphatic rings fused to aromatic rings therein; (B) optionally combining at least a portion of the C9+ aromatics stream with a first alkyl-demethylation catalyst in a first alkyl-demethylation zone under a first set of alkyl-demethylation conditions contacting to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics contained in the C9+ aromatics stream to alkyl-demethylated hydrocarbons to produce first alkanes exiting the first alkyl-demethylation zone base-demethylation effluent; (C) optionally separating the C9+ aromatics stream and/or the first alkyl-demethylation effluent in a first separation unit to obtain a C9 to C10 aromatics-rich stream and a C11+ aromatics-rich stream; (D) combining at least a portion of the first alkyl-demethylation effluent and/or at least a portion of the C9 to C10 rich aromatics stream with a second alkyl-demethylation catalyst in a second alkyl- Optional contact in the demethylation zone under a second set of alkyl-demethylation conditions to remove at least a portion of the C2+-hydrocarbyl-substituted aromatics (if in the first alkyl-demethylation effluent and and/or if contained in the C9 to C10 rich aromatics stream) is converted to alkyl-demethylated hydrocarbons to produce a second alkyl-demethylation effluent leaving the second alkyl-demethylation zone ; (E) converting at least a portion of the C9+ aromatics stream, and/or at least a portion of the first alkyl-demethylation effluent, and/or at least a portion of the C9 to C10 rich aromatics stream, and/or at least a portion the second alkyl-demethylation effluent, and the optional benzene/toluene stream are fed to the transalkylation zone; (F) contacting C9+ aromatics with benzene/toluene in the presence of a transalkylation catalyst in a transalkylation zone under transalkylation conditions to produce a transalkylation effluent leaving the transalkylation zone ;and (G) separating the transalkylation effluent in a second separation unit to obtain a random benzene product stream, a toluene-rich stream, and a C8+ aromatics-rich stream; wherein at least one of steps (B) and (D) is performed.

C2. The transalkylation method of C1, which additionally comprises: (H) separating at least a portion of the C8+ aromatics-rich stream in a third separation unit to obtain a xylene-rich stream and a C9+ aromatics-rich stream; and (I) providing at least a portion of the C9+ aromatics-rich stream as at least a portion of the C9+ aromatics stream in step (A).

C3. The transalkylation method of C1, wherein step (B) is carried out.

C4. The transalkylation process of any one of C1 to C3, wherein step (C) is carried out.

C5. The transalkylation process of C3, wherein step (C) is carried out and the C9 to C10 rich aromatics stream additionally comprises C7 and C8 aromatics.

C6. The method of any one of C1 to C5, further comprising: (J) Feeding at least a portion of the benzene product stream and/or at least a portion of the toluene-rich stream to a transalkylation zone as at least a portion of the benzene/toluene stream in step (E).

C7. The method of any one of C1 to C6, wherein the second alkyl-demethylation zone is upstream of the transalkylation zone.

C8. A method as in C4, which additionally includes: Combining at least a portion of the second alkyl-demethylation effluent and/or at least a portion of the C9 to C10 rich aromatics stream with a third alkyl-demethylation catalyst in a third alkyl-demethylation Contacting in a third set of alkyl-demethylation conditions in the alkylation zone to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if in the second alkyl-demethylation effluent and/or the C9-rich effluent) to alkyl-demethylated hydrocarbons, if contained in the C10 aromatics stream, wherein the third alkyl-demethylation zone at least partially overlaps the transalkylation zone.

C9. The method of any one of C1 to C7, wherein the second alkyl-demethylation zone at least partially overlaps the transalkylation zone.

C10. The method of any one of C1 to C9, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane The radical-demethylation catalysts, identically or differently, comprise a first metal element selected from the group consisting of Groups 7, 8, 9, and 10 metals and combinations thereof, and a support.

C11. The method of C10, wherein the first metal element is selected from the group consisting of Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and combinations thereof.

C12. The method of C10 or C11, wherein in each alkyl-demethylation catalyst, the concentration of the first metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

C13. The method of any one of C10 to C12, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane The radical-demethylation catalyst, identically or differently, additionally comprises a second metal element selected from the group consisting of Groups 11, 12, 13, and 14 metals and combinations thereof.

C14. The method of C13, wherein the second metal element is selected from group 11, 12, 13, and 14 elements, such as Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations thereof.

C15. The method of C13 or C14, wherein in each alkyl-demethylation catalyst, the concentration of the second metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

C16. The method of any one of C10 to C15, wherein the first alkyl-demethylation catalyst and/or the second alkyl-demethylation catalyst, identically or differently, additionally comprise selected from the group consisting of The third metal element of Group 1 and 2 metals and compositions thereof.

C17. The method of C16, wherein the third metal element is selected from the group consisting of: Li, N, K, Rb, Cs, Mg, Ca, Ba, and combinations thereof.

C18. The method of C16 or C17, wherein in each alkyl-demethylation catalyst, the concentration of the third metal element is based on the total weight of each alkyl-demethylation catalyst at 0.1 to within 10% by weight.

C19. The method of any one of C10 to C18, wherein the first alkyl-demethylation catalyst, and/or the second alkyl-demethylation catalyst, and/or the third alkane The radical-demethylation catalysts, identically or differently, comprise molecular sieves as at least a portion of the support.

C20. The method of any one of C1 to C19, wherein the first group of alkyl-demethylation conditions, the second group of alkyl-demethylation conditions, and the third group of alkyl-demethylation conditions The alkylation conditions comprise identically or differently at least one of the following: a temperature in the range from 200 to 500°C; an absolute pressure in the range from 350 to 2500 kPa; molecular hydrogen to hydrocarbon in the range from 0.5 to 20 and the liquid weight hourly space velocity in the range from 1 to 20 h ^-1 .

C21. The process of C20, wherein liquid phase transalkylation is carried out in the transalkylation zone.

C22. The process of C21, wherein the transalkylation conditions comprise the absence of a molecular hydrogen stream co-fed to the transalkylation zone.

C23. A method of converting aromatics, the method comprising: (A) providing a C9+ aromatics stream comprising C2+-hydrocarbyl-substituted aromatics, wherein the C2+-hydrocarbyl-substituted aromatics have (i) an aromatic ring attached to therein C2+ alkyl substituents and/or (ii) an aliphatic ring fused to an aromatic ring therein; (B) combining at least a portion of the C9+ aromatic hydrocarbon stream with a first alkyl-demethylation catalyst Optional contact in the first alkyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics contained in the C9+ aromatics stream to alkanes C9+ aromatics stream and /or the first alkyl-demethylation effluent is optionally separated to obtain a C9 to C10 aromatics-rich stream and a C11+ aromatics-rich stream; (D) separating at least a portion of the first alkyl-demethylation effluent and/or at least a portion of the C9 to C10 rich aromatics stream with a second alkyl-demethylation catalyst in a second alkyl-demethylation zone under a second set of alkyl-demethylation conditions optionally contacted to convert at least a portion of the C2+-hydrocarbyl-substituted aromatics (if contained in the first alkyl-demethylation effluent and/or the C9 to C10-rich aromatics stream) into alkyl- Demethylated hydrocarbons to produce a second alkyl-demethylation effluent leaving the second alkyl-demethylation zone; (E) demethylating at least a portion of the C9+ aromatics stream, and/or at least a portion The first alkyl-demethylation effluent, and/or at least a portion of the C9 to C10-rich aromatics stream, and/or at least a portion of the second alkyl-demethylation effluent, and optional benzene /toluene stream is fed to the transalkylation zone; (F) contacting C9+ aromatics with benzene/toluene in the presence of a transalkylation catalyst under transalkylation conditions in the transalkylation zone to produce leaving a transalkylation effluent from the transalkylation zone; and (G) separating the transalkylation effluent in a second separation unit to obtain a random benzene product stream, a toluene-rich stream, and a C8+ aromatics-rich stream; wherein: at least one of steps (B) and (D) is performed; the first set of alkyl-demethylation conditions is the same or different from the second set of alkyl-demethylation conditions comprising at least one of the following One: temperature in the range from 200 to 500°C; absolute pressure in the range from 350 to 2500 kPa; molar ratio of molecular hydrogen to hydrocarbon in the range from 0.5 to 20; and in the range from 1 to 20 The liquid weight hourly space velocity in the range of hours ^-1 ; and the first alkyl-demethylation catalyst and/or the second alkyl-demethylation catalyst, identically or differently, comprise: selected from the group consisting of: The first metal element of Groups 8, 9, and 10 metals and combinations thereof, and supports.

D1. A catalyst composition for the alkyl-demethylation of an aromatic hydrocarbon having (i) a C alkyl substituent attached to an aromatic ring therein and/or (ii) fused to In the aliphatic ring of the aromatic ring, the catalyst composition comprises the first metal element selected from the group 7, 8, 9, and 10 metals and combinations thereof, and a support.

D2. The catalyst composition of D1, wherein the first metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Re, Os, Ir, Pt, and combinations thereof.

D3. The catalyst composition of D1 or D2, wherein in the catalyst composition, the concentration of the first metal element is in the range of 0.1 to 10% by weight based on the total weight of the catalyst composition.

D4. The catalyst composition of D3, further comprising a second metal element selected from the group consisting of Groups 11, 12, 13, and 14 metals and combinations thereof.

D5. The catalyst composition of D4, wherein the second metal element is selected from: Group 11, 12, 13, and Group 14 elements, such as Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations thereof thing.

D6. The catalyst composition of D4 or D4, wherein in each alkyl-demethylation catalyst, the concentration of the second metal element is based on the total weight of each alkyl-demethylation catalyst Calculated in the range of 0.1 to 10% by weight.

D7. The catalyst composition of any one of D1 to D6, further comprising a third metal element selected from the group consisting of Groups 1 and 2 metals and combinations thereof.

D8. The catalyst composition of D7, wherein the third metal element is selected from the group consisting of: Li, N, K, Rb, Cs, Mg, Ca, Ba, and combinations thereof.

D9. The catalyst composition of D7 or D8, wherein the concentration of the third metal element is in the range of 0.1 to 10% by weight based on the total weight of the catalyst composition.

D10. The catalyst composition of any one of D1 to D9, comprising molecular sieves as at least a part of the support.

D11. The catalyst composition of D10, wherein the molecular sieve comprises zeolite.

D12. The catalyst composition of D10 or D11, wherein the molecular sieve has a specific surface area of ≥100 m ² /g.

101: Prior art methods 103: Heavy oil brain flow 105: Recombination zone 107: Recombination effluent, alkyl-demethylation effluent 109: Reconstituted Oil Separator 111: C6 to C7 rich hydrocarbon stream 113: rich C8+ aromatics stream 114: Combined Streams 115: Xylene separator 117: Xylene rich stream 119: Paraxylene Recovery Subsystem 121: paraxylene product stream 123: paraxylene depletion stream 125: Isomerization zone 127: Isomerization effluent 129: rich C9+ aromatics stream 131: Distillation column 133: C9 to C10 rich aromatics stream 135: rich C11+ aromatics stream 137: Extractive distillation zone 138: Aromatic-depleted raffinate stream 139: C6 to C7 rich aromatics stream 141: Benzene Tower 143: Benzene product stream 145: rich C8+ aromatics stream 146: Rich benzene/toluene stream 147: Transalkylation zone 149: Steam effluent, transalkylation effluent 201: Exemplary inventive method 203: alkyl-demethylation region 205: alkyl-demethylation region 207: Alkyl-demethylation effluent 209: Alkyl-demethylation region 211: Stream 213: Clean Flow 215: Stream 217: Isomerization effluent 219: Stream 303: Hydrotreated SCN stream 305: Separation System 307: C5-rich hydrocarbon stream 309: C7+ hydrocarbon-rich or C8+ hydrocarbon-rich stream 311: Benzene-rich or C6 to C7 aromatics stream 313: Extraction and separation zone 315: Non-aromatic raffinate stream 317: Aromatic-rich stream 319: Benzene Tower 321: Benzene product stream 323: Toluene-rich stream 401: Hydrotreated SCN stream 403: Hydrotreated SCN stream 405: Detach Subsystem 407: Light Hydrocarbon Stream 501: Example 503: ethyl-demethylation region 505: Alkyl-demethylation effluent 507: Alkyl-demethylation region 509: Stream 511: Stream 603: Alkyl-demethylation region 605: Alkyl-demethylation region 607: Stream 609: Alkyl-demethylation region

[ FIG. 1 ] is a schematic diagram showing a prior art method for producing para-xylene by a naphtha method including a xylene loop and a transalkylation step.

[ FIG. 2 ] is a schematic diagram showing the method of the present disclosure for producing para-xylene by a naphtha process including a xylene loop and a transalkylation step and one or more alkyl-demethylation steps.

[FIG. 3] is a schematic diagram showing a prior art method of processing hydrotreated steam cracked petroleum naphtha.

[ FIG. 4 ] is a schematic diagram showing the method of the present disclosure for producing para-xylene from hydrotreated steam cracked petroleum naphtha.

[FIG. 5] is a schematic diagram showing the C8 aromatics isomerization process of the present disclosure including one or more ethyl-demethylation steps to isomerize a C8 aromatics mixture.

[FIG. 6] is a schematic diagram showing the transalkylation process of the present disclosure including one or more alkyl-demethylation steps to transalkylate C9+ aromatics with benzene and/or toluene.

103: Heavy oil brain flow

105: Recombination zone

107: Recombination effluent, alkyl-demethylation effluent

109: Reconstituted Oil Separator

111: C6 to C7 rich hydrocarbon stream

113: rich C8+ aromatics stream

114: Combined Streams

115: Xylene separator

117: Xylene rich stream

119: Paraxylene Recovery Subsystem

121: paraxylene product stream

123: paraxylene depletion stream

125: Isomerization zone

127: Isomerization effluent

129: rich C9+ aromatics stream

131: Distillation column

133: C9 to C10 rich aromatics stream

135: rich C11+ aromatics stream

137: Extractive distillation zone

138: Aromatic-depleted raffinate stream

139: C6 to C7 rich aromatics stream

141: Benzene Tower

143: Benzene product stream

145: rich C8+ aromatics stream

146: Rich benzene/toluene stream

147: Transalkylation zone

149: Steam effluent, transalkylation effluent

201: Exemplary inventive method

203: alkyl-demethylation region

205: alkyl-demethylation region

207: Alkyl-demethylation effluent

209: Alkyl-demethylation region

211: Stream

213: Clean Flow

215: Stream

217: Isomerization effluent

219: Stream

Claims (22)

A method of isomerizing C8 aromatics, the method comprising: (i) providing a first C8 aromatics stream comprising ethylbenzene, para-xylene, meta-xylene, and optional ortho-xylene; (ii) recovering at para-xylene separating the first C8 aromatics stream in a secondary system to obtain a paraxylene product stream and a paraxylene depletion stream; (iii) separating at least a portion of the paraxylene depletion stream from the first ethyl-demethylation stream A catalyst is contacted in the first ethyl-demethylation zone to convert at least a portion of the ethylbenzene present in the p-xylene depleted stream to toluene to obtain exiting the first ethyl-demethylation the first ethyl-demethylation effluent of the chemistry zone; (iv) combining at least a portion of the first ethyl-demethylation effluent and optionally at least a portion of the paraxylene depletion stream with the first two contacting a toluene isomerization catalyst under a first set of xylene isomerization conditions in a first xylene isomerization zone to obtain a first xylene isomerization effluent; and (v) subjecting at least a portion of the A first xylene isomerization effluent is supplied to the paraxylene recovery subsystem to obtain the paraxylene product stream and the paraxylene depletion stream, wherein the first xylene isomerization zone is the first Downstream of the ethyl-demethylation zone. The method of claim 1, further comprising: (iva) combining at least a portion of the paraxylene depleted stream and/or at least a portion of the first ethyl-demethylation effluent with a second ethyl-demethylation stream Methylation catalyst in the second set of ethyl-demethylation in the first xylene isomerization zone contacting under conditions to convert at least a portion of the ethylbenzene present in the first isomerization zone to toluene. The method of any one of claims 1 to 2, wherein the first xylene isomerization zone at least partially overlaps the first ethyl-demethylation zone. The method of any one of claims 1 to 2, wherein liquid phase isomerization is carried out in the first xylene isomerization zone. The method of claim 4, wherein substantially all of the first ethyl-demethylation effluent is fed to the first xylene isomerization zone. The method of claim 4, wherein the first set of xylene isomerization conditions excludes molecular hydrogen co-fed to the first isomerization zone. The method of any one of claims 1 to 2, wherein vapor phase isomerization is carried out in the first xylene isomerization zone. The method of claim 7, wherein the first portion of the first ethyl-demethylation effluent is fed into the first xylene isomerization zone, and the method additionally comprises: (vi) the first xylene isomerization zone A second portion of the monoethyl-demethylation effluent is contacted with a second xylene isomerization catalyst in a second xylene isomerization zone under a second set of xylene isomerization conditions to produce a second xylene isomerization catalyst. Xylene isomerization effluent, wherein liquid phase isomerization is performed in the second xylene isomerization zone; (vii) at least a portion of the second xylene is recovered in the para-xylene recovery subsystem The toluene isomerization effluent is separated to obtain the paraxylene product stream with The paraxylene depletion stream. The method of any one of claims 1 to 2, further comprising: (viii) directing a portion of the paraxylene depleted stream as a first wash stream. The method of claim 8, further comprising: (ix) directing a portion of the first isomerization effluent and/or a portion of the second isomerization effluent as a second wash stream. The method of any one of claims 1 to 2, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst, identically or differently, comprise: selected from The first metal element of Groups 7, 8, 9, and 10 metals and compositions thereof, and a support. The method of claim 11, wherein the first metal element is selected from the group consisting of Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and combinations thereof. The method of claim 11, wherein based on the total weight of each ethyl-demethylation catalyst, the concentration of the first metal element in each ethyl-demethylation catalyst is in the range from In the range of 0.1 to 10% by weight. The method of claim 11, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst, identically or differently, additionally comprise the group selected from 11, 12, 13, and the second metal element of Group 14 metals and their compositions. The method of claim 14, wherein the second metal element The element is selected from: Cu, Ag, Au, Zn, Al, Ga, Sn, and combinations thereof. The method of claim 14, wherein based on the total weight of each ethyl-demethylation catalyst, the concentration of the second metal element in each ethyl-demethylation catalyst is in the range from In the range of 0.1 to 10% by weight. The method of claim 11, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst, identically or differently, additionally comprise metals selected from Groups 1 and 2 and The third metal element of its composition. The method of claim 17, wherein the third metal element is selected from the group consisting of: Li, N, K, Rb, Cs, Mg, Ca, Ba, and combinations thereof. The method of claim 17, wherein based on the total weight of each ethyl-demethylation catalyst, the concentration of the third metal element in each ethyl-demethylation catalyst is in the range from In the range of 0.1 to 10% by weight. The method of claim 11, wherein the first ethyl-demethylation catalyst and/or the second ethyl-demethylation catalyst identically or differently comprise molecular sieves as at least a part of the support. The method of any one of claims 1 to 2, wherein the first and second sets of alkyl-demethylation conditions, the same or different, comprise at least one of the following: a temperature in the range from 200 to 500°C temperature; absolute pressure in the range from 350 to 2500 kPa; molar ratio of molecular hydrogen to hydrocarbon in the range from 0.5 to 20; and liquid weight hourly space velocity in the range from 1 to 20 h ^-1 . A method of converting C8 aromatics, the method comprising: (i) providing a first C8 aromatics stream comprising ethylbenzene, para-xylene, meta-xylene, and optional ortho-xylene; (ii) in a para-xylene recovery sub-system (iii) contacting at least a portion of the paraxylene depleted stream with the first ethyl-demethylation The medium is contacted in a first ethyl-demethylation zone under a first set of alkyl-demethylation conditions to convert at least a portion of the ethylbenzene present in the para-xylene depleted stream to toluene, to obtaining a first ethyl-demethylation effluent leaving the first ethyl-demethylation zone; (iv) combining at least a portion of the first ethyl-demethylation effluent and optionally at least a portion of the The paraxylene depleted stream is contacted with a first xylene isomerization catalyst in a first xylene isomerization zone under a first set of xylene isomerization conditions to obtain a first xylene isomerization effluent and (v) supplying at least a portion of the first xylene isomerization effluent to the paraxylene recovery subsystem to obtain the paraxylene product stream and the paraxylene depletion stream; wherein: the The first group of ethyl-demethylation conditions includes: temperatures in the range from 200 to 500°C; absolute pressures in the range from 350 to 2500 kPa; molecular hydrogen to hydrocarbons in the range from 0.5 to 20 and a liquid weight hourly space velocity in the range from 1 to 20 hours ^-1 ; and the first ethyl-demethylation catalyst comprises: a metal selected from the group consisting of Groups 7, 8, 9, and 10, and The first metal element of its composition, and the support, and wherein the first xylene isomerization zone is downstream of the first ethyl-demethylation zone.

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