RU2822069C2 - Isomerisation method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for combined reforming of ethylbenzene and isomerisation of xylene and is characterized by contacting a hydrocarbon feedstock containing ethylbenzene and xylene, with a catalyst for catalysis of a combined reaction of reforming ethylbenzene and isomerisation of xylene. Catalyst is the only catalyst present in the process, and said catalyst comprises a catalyst support and one or more Group VIII metals, including platinum, deposited on the catalyst support. Catalyst carrier is an extrudate containing a zeolite of the ZSM-48 and/or EU-2 type, as well as an aluminium oxide-based binder, wherein the extrudate has a shape with a C/A value of at least 3, where C is the length of the curved surface of the extrudate and A is the cross-sectional area of the extrudate. Cross-sectional area A of the extrudate is measured perpendicular to the axis of the extrusion, the length of the curved surface C of the extrudate is the length of the perimeter of the extrudate around the cross-section, and binder based on aluminium oxide is aluminium oxide with wide pores, having average pore diameter of 80 Å or more.

EFFECT: providing an improved method of reforming alkyl aromatic hydrocarbons, especially C8 alkyl aromatic hydrocarbons, such as ethylbenzene, and isomerisation of xylenes.

5 cl, 1 dwg, 1 tbl, 1 ex

Description

Field of technology

The present invention relates to a process for reforming ethylbenzene and isomerizing xylenes using a zeolite catalyst.

State of the art

After fractionation or distillation of crude oil, a straight-run naphtha fraction with a boiling point of 70°C to 190°C is obtained. This fraction can be catalytically converted to an aromatic reformate.

When converted to a reformate, the aromatic hydrocarbon content increases significantly and the resulting mixture of hydrocarbons becomes highly desirable as a source of valuable chemical intermediates and as a component of gasoline.

The reformate typically contains 8-carbon aromatic hydrocarbons such as ethylbenzene and xylenes. Other components may be present, such as their hydrogenated homologues such as naphthenes.

Among the xylenes, the most useful compound is para-xylene, and isomerization or transalkylation processes have been developed to increase the proportion of para-xylene (“pX”). However, isomerization or transalkylation methods can also produce undesirable by-products such as compounds containing 1 to 5 carbon atoms, benzene, toluene, and compounds containing 9 or more carbon atoms.

Many catalysts have been manufactured and proposed for various reactions involving aromatic compounds, but for some reactions, such as ethylbenzene isomerization or transalkylation processes, there is usually a trade-off between obtaining the desired products and known side reactions. One of the common side reactions of ethylbenzene, hydroisomerization, is the formation of compounds containing from 1 to 5 carbon atoms, which is unfavorable from an environmental and economic point of view.

US 3,856,872 A describes a xylene isomerization process in which the conventional platinum-silica-alumina catalyst is replaced by a ZSM-5 type zeolite catalyst, or a ZSM-12 zeolite catalyst, or a ZSM-21 zeolite catalyst. The zeolite may be included in an inert alumina matrix.

In the article “Dealuminated zeolite-based composite catalysts for reforming of an industrial naphthene-rich feedstock,” Applied Catalysis, Volume 168, Issue 1, March 1998, pp. 113-130) describe reforming catalysts for naphthenic feedstock. The preferred zeolite ZSM-12 has a Si/Al ratio of 54. It is reported that ZSM-12, which has a higher silica to alumina ratio, should not be used for such catalysts because it produces higher amounts of CH4 and lower amounts of aromatics.

Other catalysts known for use in C8 aromatic isomerization processes include mordenite (MOR) and EU1 (EUO) zeolite catalysts as defined in the Atlas of Zeolite Framework Types, Olson et al, 5th revised edition, 2001, published on behalf of the Structural Commission of the International Zeolite Association, by Elsevier. EU1-based catalysts can achieve high selectivity, but this is usually accompanied by low ethylbenzene conversion rates, which limits productivity. MOR and ZSM-12 catalysts generally provide higher ethylbenzene conversion, but they also produce more toluene and C9+ aromatic hydrocarbon by-products.

From US 4741891 A and US 5075269 it is known that ZSM-48 and/or EU-2 zeolites are suitable for use in hydrocarbon conversion catalysts. As described in the Catalog of Disorder in Zeolite Frameworks published in 2000, ZSM-48 and EU-2 zeolites belong to the ZSM-48 zeolite family.

WO 2012055755 A1 describes dealuminated ZSM-48 and/or EU-2 zeolites with a refractory oxide substantially free of alumina for use as hydrocarbon conversion catalysts.

It is an object of the present invention to provide an improved process for reforming alkyl aromatic hydrocarbons, especially C8 alkyl aromatic hydrocarbons such as ethylbenzene, and isomerizing xylenes.

Brief description of the invention

Surprisingly, it has been found that this object can be achieved by using a catalyst system containing ZSM-48 and/or EU-2 zeolite, especially a molded catalyst system of ZSM-48 and/or EU-2 zeolite, in which the curve length of the surface of the molded catalyst increased compared to its cross-sectional area.

Accordingly, the present invention provides a process for the combined reforming of ethylbenzene and isomerization of xylene, comprising contacting a hydrocarbon feedstock containing ethylbenzene and xylene with a catalyst containing a catalyst support and one or more metals supported on the catalyst support, wherein the catalyst support is an extrudate containing ( i) a ZSM-48 and/or EU-2 type zeolite and (ii) an alumina binder, the extrudate having a shape with a C/A value of at least 3, where C is the length of the curved surface of the extrudate and A is the cross-sectional area of the extrudate .

Detailed Description of the Invention

In the present invention, it has been found that the use of the above shaped catalyst support extrudate is surprisingly useful for providing a catalyst for the isomerization of alkyl aromatic compounds containing 8 carbon atoms. In addition, the molded catalyst used in the method according to the present invention is capable of: reducing side reactions such as the formation of compounds containing from 1 to 5 carbon atoms, and/or reducing the formation of benzene, and/or increasing the conversion of ethylbenzene, and/or increasing production of other desired products such as para-xylene.

One of several of the above positions results in an increase in the final yield of one or more of the desired products and unexpectedly results in high pC-approximation to equilibrium (“pC-ECR”) values while maintaining excellent ethylbenzene conversion.

In the present invention, reference to ZSM-48 and EU-2 is used to indicate that any zeolites that belong to the MRE family of disordered structures, as described in the "Catalog of Disorder in Zeolite Frameworks", published in 2000, ed. Structural Commission of the International Zeolite Association. Zeolites ZBM-30 and EU-11 are very similar to ZSM-48 and are also considered members of the zeolite family, whose structure belongs to the MRE family. Thus, in this application, any reference to ZSM-48 zeolite is also a reference to EU-2, ZBM-30 and EU-11 zeolite.

The molar ratio of silica to alumina in ZSM-48 and/or EU-2 zeolite can affect the properties of the resulting catalyst. The molar ratio of silicon oxide to alumina (“SCA”) must be determined by the volume ratio. This ratio is also called the overall ratio. This relationship differs from the OCA of the crystalline framework. The volumetric or total ratio can be determined by various methods of chemical analysis. Such methods include X-ray fluorescence, atomic adsorption and inductively coupled plasma atomic emission spectroscopy (ICP-AES). They all provide essentially the same volume ratio. The molar ratio of silica to alumina for use in the present invention is determined by X-ray fluorescence.

The TCA of ZSM-48 and/or EU-2 zeolite is preferably at least 50, more particularly at least 70, more particularly at least 100, most preferably at least 110. TCA of ZSM-48 and/or EU-2 zeolite preferably is no more than 300, more particularly no more than 250, more particularly no more than 200, most particularly no more than 160.

Zeolite ZSM-48 and/or EU-2 can be prepared by any method known to one skilled in the art. US Pat. No. 5,075,269 and US Pat. No. 4,741,891 describe suitable methods for preparing such zeolites having an RCA of 100 to 250.

Zeolite ZSM-48 and/or EU-2 can be dealuminated. Dealumination can be achieved by methods known in the art, such as, for example, acid leaching or steam treatment. Steam treatment is accomplished by contacting the zeolite, preferably as part of the catalyst composition, with steam at elevated temperatures ranging from about 250°C to 650°C and preferably from about 400°C to 550°C. The treatment may be carried out in an atmosphere of 100% steam or in an atmosphere consisting of steam or other gas which is substantially inert to the zeolites. Such processing can be carried out at lower temperatures and higher pressures, for example, at temperatures from 180°C to 370°C and pressures from 10 to 200 atmospheres.

The expression "dealumination" is used to mean that aluminum and/or aluminum-containing compounds such as aluminum oxide are removed from the bulk of the zeolite. Aluminum and aluminum-containing compounds may, but are not required to, form part of the zeolite framework.

ZSM-48 and/or EU-2 zeolite is combined with an alumina binder in the catalyst support of the present invention. In one embodiment, the alumina binder preferably includes "wide pore alumina", which is sometimes alternatively referred to as "large pore" alumina. By "wide pore alumina" is meant that the average pore diameter of the alumina is about 80 Å or greater, preferably greater than about 90 Å. In another embodiment, the wide pore alumina may have a surface area greater than about 200 m ² /g, and about 25% or more of its pores have a diameter greater than about 350 Å.

Said wide pore alumina may have a pore volume of at least about 0.5 cm ³ /g, preferably at least 0.6 cm ³ /g, and more preferably at least 1.2 cm ³ /g. The pore volume can be up to about 2.0 cm ³ /g, preferably up to 1.6 cm ³ /g.

The more open, wide-pore structure of alumina, based on one or more parameters such as pore volume, pore diameter, and bulk density, is believed to provide better diffusion of the reactant(s) reaching the catalytic material in the catalyst and better diffusion of the product(s) ) from catalytic material.

Examples of wide pore alumina suitable for use in the catalyst of the present invention include grades in the Pural range from Sasol such as "Pural KR II" (average bulk density 0.315 g/cm ³ , pore volume 1.4 cm ³ /g and average surface area 290 m ² /g) and other wide pore aluminas such as WPA available from Criterion (average bulk density 0.2 g/cm ³ , pore volume 1 cm ³ /g and average surface area 345 m ² /G). Pore size and pore volume can be measured using mercury penetration porosimetry (MPT).

When binder and zeolite content is indicated in the context of this invention, the content is meant on a dry matter basis. The catalyst composition for use in the method according to the present invention preferably contains no more than 80% by weight (% wt.) of zeolite, more specifically, no more than 70% wt., more specifically, no more than 65% wt., most preferably, no more than 55% wt. . These amounts preferably refer to ZSM-48 and/or EU-2 zeolite. Moreover, it is preferable that the amount of ZSM-48 and/or EU-2 zeolite is at least 30 wt%, more particularly at least 35 wt%, more particularly at least 40 wt%, most particularly at at least 45% of the mass.

Optionally, in addition to ZSM-48 and/or EU-2 zeolite, other zeolites may be present in the catalyst composition, especially if it is desired to change its catalytic properties. If additional zeolite is present in addition to ZSM-48 and/or EU-2 zeolite, such zeolite is preferably present in an amount of not more than 50% by weight. based on the amount of ZSM-48 and EU-2 zeolites present.

A combined alkyl aromatic hydrocarbon reforming and xylene isomerization catalyst for use in the process of the present invention can be prepared by extruding a mixture containing a ZSM-48 and/or EU-2 type zeolite and alumina to form a catalyst support having a C/A value of not less than 3, and impregnation of the extruded catalyst carrier with metal.

The catalyst support may be extruded before loading with metal. Preferably, the catalyst support is calcined before loading with metal. Calcination can take place at 350-850°C, more preferably at 400-750°C in an inert atmosphere or oxygen-containing gas.

The catalyst support is molded or formed by extrusion, for example by preparing an extrudable mass containing an alumina binder and ZSM-48 and/or EU-2 zeolite. This extrudable mass may have a viscosity that allows extrusion into molds, preferably the viscosity should be such that the extruded shapes are retained during subsequent calcination. One skilled in the art will know how to make an extrudable mixture, such as a paste mixture, that is susceptible to such extrusion and then retaining its extruded shape when calcined. For example, the extrudable mass preferably has a water content sufficient to permit extrusion while maintaining the extruded shape during subsequent calcination. Preferably, the water content does not exceed 65% and preferably is not less than 35% by weight.

The mixture of zeolite and alumina may further contain a peptizing agent to change the pH of the mixture sufficiently to cause deagglomeration of the solids. Peptizing agents are well known and include inorganic acids such as sulfuric acid or nitric acid, as well as organic acids such as formic acid and acetic acid. Such peptizing agents are removed by calcination.

A plasticizing agent may be added to the catalyst support composition, preferably the plasticizing agent is added before extrusion. A plasticizing agent can be used to increase the viscosity of the mixture to obtain an extrudable mass. Suitable plasticizing agents are, for example, dextrose, gelatin, glucose, glues, gums, salts, waxes, starch and cellulose ethers. Methylcellulose and/or methylcellulose derivatives are particularly suitable as organic binders in the practice of the present invention, with methylcellulose, hydroxypropylmethylcellulose or combinations thereof being preferred. Preferred sources of cellulose ethers are Methocel A4M, F4M, F240 and K75M from Dow Chemical Co.

Extrusion of the catalyst support composition can be carried out by any of the well known extrusion methods. Examples of such methods are extrusion performed using a screw extruder, plate extruder or plunger extruder.

Extrudates can have a variety of shapes and sizes, provided that the C/A value is at least 3, where C is the length of the curved surface, and A is the cross-sectional area of the extrudate. Note that the cross-sectional area (A) of the extrudate is measured at right angles (perpendicular) to the extrusion axis, and its surface curve length (C) is the perimeter length of the extrudate's cross-sectional curve. Extrudates having a C/A value of at least 3 may conveniently be formed as cylindrical or multi-lobed extrudates, for example having a tri-lobe, quad-lobe or elongated tri-lobe shape. That is, in the present invention, the cross-section of the catalyst support preferably has a round, three-lobe, four-lobe or elongated three-lobe shape. More preferably, the cross-section of the catalyst support has a three-lobe, four-lobe, or elongated three-lobe shape.

An extrudable composition containing ZSM-48 and/or EU-2 zeolite and an alumina binder can be extruded using extruder die plates provided with orifices that produce an extrudate having the required cross-section to achieve a C/A value of at least 3 .

After extrusion, the resulting extrudates are preferably dried before calcination. Drying preferably occurs at a temperature of from 60°C to 250°C for a time sufficient to dry the extrudate, for example, for at least 1 hour. The calcination preferably occurs in an oxygen-containing gas, including air, or an inert gas, at temperatures from 250°C to 850°C for periods of time, for example, from 1 to 48 hours or more.

The extruded catalyst supports may be separated, for example cut or broken, preferably after an initial calcination step, to reduce their length to diameter ratio and thereby help reduce catalyst degradation, for example when they are subjected to crushing forces in the catalyst bed in the reactor. The length to diameter ratio may optionally be in the range of 1:1 to 20:1, preferably 2:1 to 9:1, most preferably 4:1 to 8:1. For example, the diameter of the extruded catalyst may be in the range of 0.5 to 5 mm, preferably 1 to 2 mm, and the average length of the catalyst molds may be in the range of 2 to 10 mm, preferably 4 to 9 mm, more preferably about 8 mm mm.

The catalyst further contains one or more metals, preferably included in the catalyst support. The metal may be incorporated by impregnation of the zeolite, impregnation of the alumina support, or impregnation of a zeolite-support composite. Preferably the metal is included in the catalyst support. Metal incorporation can be accomplished using ion exchange methods, such as contacting a catalyst support composition with a salt of the desired metal ion. This can be done, for example, by impregnation of the pore volume or by continuous impregnation with a solution. Typical ion exchange methods are disclosed in a large number of patent specifications, including US 3,140,249 A, US 3,140,251 A, and US 3,140,253 A.

The catalytic metal(s) are preferably incorporated by infiltrating the pore volume. More preferably, the metal(s) are incorporated by impregnation into the extruded catalyst support, for example after calcination of the support. Most preferably, impregnation is carried out both after calcination and after dividing the extruded support to the desired length(s).

The catalytic metal(s) are selected from the group consisting of metals of Group VIII of the Periodic Table of the Elements, as shown in the Handbook of Chemistry and Physics, 63rd edition 1983, more specifically selected from one or more of the following elements: platinum, palladium, cobalt, iron and nickel. Preferably, one or more catalyst metals is selected from the group consisting of platinum, palladium and nickel, with platinum being particularly preferred. Combinations of two or more catalytically active metals are also possible, preferably combinations of platinum metals. The catalytically active metal may be in the form of a compound, optionally requiring activation before use.

The catalytic metal may be included in the final catalyst composition in an amount of up to about 3% by weight. based on the total dry weight of the catalyst, the metal content being determined as an element, regardless of its actual form. It is preferable that the metal component is present in the catalyst composition in an amount of from 0.1 to 3 wt%. More preferably, the metal is present in the composition in an amount of from 0.2 to 2% by weight, and most preferably, it is present in the range of from 0.3 to 1% by weight. More preferably, the catalyst composition contains about 0.3 wt%. platinum.

The catalyst finds use in isomerization and reforming processes, especially ethylbenzene conversion and xylene isomerization, as described herein.

Advantageously, the catalysts prepared as described above can be used in the isomerization of alkyl aromatic hydrocarbons to produce a product with an increased xylene content.

The catalysts described herein are particularly suitable for use in increasing the xylene content, more particularly the para-xylene content, in a hydrocarbon fraction containing 8-carbon aromatic hydrocarbons. The hydrocarbon stream preferably contains no more than 60 wt.%. ethylbenzene, more specifically, not more than 50% of the mass. Preferably, the hydrocarbon stream contains at least 8 wt.%, more specifically at least 10 wt.%, most preferably at least 15 wt.%. ethylbenzene. The hydrocarbon stream preferably comes into contact with the catalyst at a temperature in the range of 300 to 450 °C, preferably at least 340 °C and preferably not more than 400 °C.

In the process of the present invention, it has surprisingly been found that in addition to successful conversion rates of ethylbenzene, further improvements in isomerization to high para-xylene content para-xylene reformate are achieved, as evidenced by pC-PCR values. pC-PCR (approximation of para-xylene equilibrium) provides a measure of the efficiency of the catalyst for increasing para-xylene concentration relative to the maximum achievable para-xylene concentration based on the thermodynamic equilibrium mixture of xylenes, as defined by the equation:

pK-PCR (%) = pK in Ksi _pr. - pK in Ksi _s.

pK to Xi _eq. - pK in Xi _s.

where pK denotes para-xylene, Xi denotes xylenes in general, c. denotes raw materials, etc. denotes the product.

In particular, it is surprising that with the present invention, pC-PCR values approaching or exceeding 100% can be achieved while maintaining low levels of by-product formation.

Examples of catalyst shapes having a C/A value of at least 3 are shown in cross section in Figure 1(b), (c) and (d), together with a cylindrical shape as in Figure 1(a), for comparisons. Catalysts of the present invention containing extrudates having a tri-lobe (TL), quad-lobe (QLSA) or tri-lobe extended (TX) cross-section have been found to exhibit improved performance, for example, compared to conventional cylindrical (CYL) extrudates having a round shape cross-section and a C/A value less than 3. A similar improvement is observed for smaller diameter cylinders, which also have C/A values above 3. On the other hand, large TX shape extrudates with a C/A value below 3 show no benefit.

C/A values of 3 or more can be achieved, for example, by extruding the catalyst through a die provided with an orifice having a wavy perimeter. In a preferred embodiment, the shaped catalyst of the invention has a solid structure, for example formed by extrusion through a solid die, rather than through a hollow die, which produces hollow or semi-hollow shapes.

The C/A ratio for the various catalyst shapes (a) - (d) in Figure 1 can be determined by measuring the radius r as indicated in the cross-sectional drawings and the surface curve length (C) represented by the thick lines in the said drawings, calculated from the following formulas:

Form Square Surface Curve Length CYL(a) TL(b) QLI(c) TX(d)

Preferably, the catalyst is formed, for example by extrusion, into shapes having a length to diameter ratio of from 1:1 to 20:1, preferably from 2:1 to 9:1, most preferably from 4:1 to 8:1. Preferably, the diameter (d) is in the range from about 0.5 mm to about 5 mm, more preferably from 1 mm to 2 mm. The molds preferably have an average length (measured along the extrusion axis) of about 2 mm to about 10 mm, more preferably from about 4 mm to about 9 mm, most preferably about 8 mm.

The catalysts described above can be used in the combined reaction of ethylbenzene reforming and xylene isomerization, the reaction being carried out in the gas phase. Accordingly, the present invention provides a process for the combined reforming of ethylbenzene and isomerization of xylene, comprising contacting a hydrocarbon feedstock containing ethylbenzene and xylene with a catalyst as described above at an elevated temperature, preferably from 340 to 450 ^o C, and a pressure from 4 to 12 bar hut Preferably, the reforming and isomerization reaction is carried out using an hourly feed space velocity (FHSV) (weight of feed per hour/weight of catalyst) in the range of from about 1 to 20 h ^-1 , more preferably from about 3 to 10 h ^-1 . MOOC is calculated based on the mass of the catalytic composition, that is, on the total mass of the active catalyst and binder.

Preferably, the isomerization reaction is carried out in the presence of hydrogen. More preferably, hydrogen may be present in the isomerization reaction zone in an amount of from about 0 to about 10 moles, especially from about 1 to about 5 moles of hydrogen per mole of hydrocarbon feedstock. The reaction can occur in vapor, liquid or mixed phase.

One of the advantages of the process according to the present invention is the fact that the process can employ a high mass hourly space velocity, which results in a much higher throughput in the reactor and therefore higher productivity. The mass hourly space velocity used in the process is typically in the range of 3 to 12 h ^-1 .

The present invention will be further illustrated by the following non-limiting examples.

EXAMPLES

Example 1

The catalyst is obtained by a method that includes the following stages: extrusion of the catalyst carrier, calcination of the carrier, impregnation with platinum and final calcination.

Specifically, an extrudable mixture of 78 g EU-2 zeolite with a silica to alumina ratio of 110 (prepared as described in US 4741891 A), 64 g wide pore alumina from Criterion, 86 g water and 2.77 g 65% HNO ₃ was prepared immediately before molding and was extruded using extruder spun plates with variously shaped holes, with the dimensions shown in Table 1.

Each resulting extruded catalyst support was calcined at 600°C for 2 hours in a stationary oven and then ground to an average length of 6 mm. Then the calcined supports were impregnated with platinum by impregnating the pore volume using a mixture of hydroplatinic acid in a 0.5 M aqueous solution of HNO _3, dried at 120°C for 2 hours, and then calcined at a temperature of 550°C for 2 hours, to obtain the finished catalysts containing 0.3% wt. platinum.

Example 2

The catalysts prepared by the method of Example 1 were then used in the ethylbenzene reforming process.

Specifically, the catalysts were evaluated in a pilot plant for the combined reaction of ethylbenzene reforming and xylene isomerization using real-time GC analysis.

A hydrogen:hydrocarbon molar ratio of 4 was maintained throughout the reaction. Before carrying out the reforming process, the catalysts were dried in a stream of hydrogen at room temperature and atmospheric pressure for 1 hour, then heated to 400°C for 4 hours, pressurized to 12 barg. and kept under these conditions for another 1 hour.

The first hydrocarbon feedstock, consisting of 20% wt. ethylbenzene and 80% wt. meta-xylene, was introduced at MCHOS 5 h ^-1 , and the temperature was raised to 420°C. These conditions were maintained for 24 hours before the temperature was reduced to 375°C. At this temperature, the hydrocarbon feedstock was switched to a mixture of 20% ethylbenzene, 23% ortho-xylene and 57% meta-xylene at an MOOC of 4.0 h ^-1 . These conditions were maintained for 6 hours.

The reactor temperature was then raised to 387°C and the hydrocarbon feedstock was switched to a final mixture of 19% ethylbenzene, 15.5% ortho-xylene, 59% meta-xylene and 6.5% ethylcyclohexane, a member of the C8-naphthenes. which mediate the reforming reaction of ethylbenzene, with MOOC 3.5 h ^-1 .

The pressure was adjusted so that the level of C8-naphthenes in the product stream was equal to the level of ethylcyclohexane in the feed. The product stream was analyzed by real-time GC for 10 hours at 3.5 h ^-1 MOOC, followed by 4 hours at 6.0 h ^-1 MOOC. Based on these data, the parameters in Table 1 were determined.

Table 1

MChOS=3.5 h ^-1 MChOS=6.0 h ^-1 Form r α C/A ^a EB conversion pK-PCR EB conversion pK-PCR CYL (compared) 0.70 - 2.86 45.1 99.2 28.9 94.0 TX
(compare) 0.51 - 2.72 42.3 98.7 27.0 91.6 CYL 0.50 - 4.0 46.1 100.1 29.9 96.8 CYL 0.20 - 10.0 48.1 100.6 32.1 98.5 TL 0.34 22 4.30 44.5 100.2 31.1 96.9 QLSA 0.36 22 3.42 41.2 100.1 27.7 96.9 TX 0.29 - 4.76 41.4 100.0 28.0 96.7 TX 0.26 - 5.44 41.8 100.0 28.4 97.1

^a is the length of the curved surface (C)/cross-sectional area (A) of the extrudate.

The results presented in Table 1 unexpectedly demonstrate that the pC-PCR values of both MOOCs tested increase significantly when the C/A ratio of the catalyst extrudates increases from 2.86 (comparative cylinders) or 2.72 (comparative TX form extrudates) to more 3. At the same time, the conversion of ethylbenzene (EB) is maintained at an excellent level.

One skilled in the art will appreciate that the present invention can be practiced in many different ways without departing from the scope of the claims.

Claims (11)

1. A method for combined reforming of ethylbenzene and xylene isomerization, where the method includes: contacting hydrocarbon feedstock containing ethylbenzene and xylene with a catalyst to catalyze the combined reaction of ethylbenzene reforming and xylene isomerization, wherein said catalyst is the only catalyst present in the process, and wherein said catalyst comprises a catalyst support and one or more Group VIII metals supported on the catalyst support, wherein the catalyst support is an extrudate containing: (i) zeolite type ZSM-48 and/or EU-2, and (ii) an alumina-based binder, wherein the extrudate has a shape with a C/A value of at least 3, where C is the length of the curved surface of the extrudate, and A is the cross-sectional area of the extrudate, wherein the cross-sectional area A of the extrudate is measured perpendicular to the extrusion axis, and the curved surface length C of the extrudate is the length of the perimeter of the extrudate around the cross-section, wherein the Group VIII metal is platinum, and wherein the alumina binder is wide pore alumina having an average pore diameter of about 80 or more. 2. The method according to claim 1, characterized in that the cross-section of the catalyst carrier has a circular shape, a three-lobe shape, a four-lobe shape or an elongated three-lobe shape. 3. The method according to claim 1 or 2, characterized in that the cross-section of the catalyst carrier has a three-lobe, four-lobe or elongated three-lobe shape. 4. Method according to any one of paragraphs. 1-3, characterized in that the zeolite is present in an amount from 30 to 70% of the mass. of the total mass of the catalyst. 5. Method according to any one of paragraphs. 1-4, characterized in that the Group VIII metal is present in an amount of from 0.1 to 3% by weight, preferably from 0.2 to 1% by weight, based on the total weight of the catalyst.