WO2002028989A1

WO2002028989A1 - Method for producing diesel fuel by moderate pressure hydrocracking

Info

Publication number: WO2002028989A1
Application number: PCT/FR2001/003016
Authority: WO
Inventors: Pierre Marion; Eric Benazzi; Didier Duee; Christophe Gueret; Alain Billon
Original assignee: Institut Francais Du Petrole
Priority date: 2000-10-05
Filing date: 2001-09-28
Publication date: 2002-04-11
Also published as: KR20030036889A; JP2004510875A; FR2815041B1; US20040050753A1; DE60142843D1; JP4939724B2; FR2815041A1; BR0114280A; EP1330505A1; KR100738294B1; TWI225889B; EP1330505B1; ES2351112T3; ATE478127T1; BR0114280B1

Abstract

The invention concerns a moderate pressure hydrocracking method (that is partial hydrogen pressure higher than 70 bars up to a maximum of 100 bars) with conversion of at least 80 % by volume, of a feedstock having a temperature T5 ranging between 250 and 400 °C and a temperature T95 of not more than 470 °C (T5 and T95 measured according to ASTM-D2887), so as to produce a diesel fuel having a 95 % distillation point less than 360 °C, a sulphur content of not more than 50 ppm and a cetane index higher than 51. The method operates with or without recycling the liquid effluent. It can advantageously be integrated in a refinery configuration comprising catalytic cracking. The invention also concerns an installation for implementing said method.

Description

PROCESS FOR PRODUCING DIESEL BY MODERATE PRESSURE HYDROCRACKING

The invention relates to a process with hydrocracking at moderate pressure, for the production of very high quality diesel with high yields.

The invention also relates to a process including said hydrocracking process and a catalytic cracking process, as well as the installation usable for implementing said process.

The refining industry must now find refining schemes to adapt to the tightening of fuel quality standards which will be in force in Europe in 2005. The maximum sulfur content in diesel must be at most 50 ppm. The 95% distillation point (ASTM D-86) of diesel, currently 360 ° C, will probably be reduced, for example by 10 ° C, which would currently represent for a refinery a decrease of 5% in volume of diesel produced. It is also envisaged to divide at least in half the present polyaromatic contents which are approximately 11% by mass. Currently. The cetane number required would also be increased beyond 51, for example from the current value of 51 to 52.

At the same time, demand for diesel continues to grow and demand is expected to increase by almost 20% in the decade.

Since the distillation of crude oil is not sufficient to cover the production of diesel, diesel is currently produced by hydrocracking processes at high pressure (generally at least 120 bars in partial hydrogen pressure) treating heavy loads which are fillers having a temperature Tgs most often of the order of at least 500 ° C., T ₉₅ being the temperature of the point 95% volume obtained by simulated distillation (ASTM-D28 87). Heavy compounds are cracked into lighter compounds, part of which is found in the middle distillate cut (diesel and kerosene) from the hydrocracking distillation. Such high pressure processes are conventional.

To achieve the new standards, the crude distillation diesel will have to undergo deep hydrodesulfurization. In addition, high pressure hydrocracking is a solution which can prove to be expensive. We therefore sought a more advantageous solution which, moreover, could be integrated into existing units to make the best use of the existing resources of the refinery. The process set out in the present application is a hydrocracking process operating at moderate pressures (above 70 bars and at most 100 bars under partial hydrogen pressure) which makes it possible to directly obtain a diesel which meets the 2005 specifications at from relatively light loads in more economical conditions than high pressure hydrocracking.

More specifically, the invention relates to a method for producing a diesel having a 95% distillation point of less than 360 ° C., a sulfur content of at most 50 ppm and a cetane number greater than 51, said method treating fillers. hydrocarbons having a temperature T ₅ of between 250 and 400 ° C and a temperature T ₉₅ of at most 470 ° C, said process comprising hydrotreatment and then hydrocracking under a partial pressure of hydrogen greater than 70 bars and at most 100 bars, ^' at a temperature of at least 320 ° C, with a H2 / load volume ratio of at least 200 NI / NI, an hourly volume speed of 0.15-7h ^"1 and the process carrying out a conversion d at least 80% by volume and the liquid effluent obtained by hydrocracking being distilled to separate the diesel, preferably the distillation residue is recycled in the process after purging.

Fillers, hydrotreatment, hydrocracking

The feeds treated in the process have a point T ₅ of between 250 and 400 ° C and preferably between 280 and 370 ° C. The point T ₅ represents the temperature of the point 5% volume obtained by simulated distillation (ASTM-D28 87).

Generally, the charges have a point T ₅ between 320-400 ° C or between 320-370 ° C. Very advantageously, a fraction of the diesel, for example heavy diesel obtained from the atmospheric distillation of crude oil, which most often has a point T ₅ of the order of at least 280 ° C., can be added to these charges. This heavy diesel fraction can just as easily be obtained directly in the atmospheric residue.

This arrangement (addition of diesel) is particularly advantageous. Indeed, it makes it possible to treat, by hydrotreatment followed by hydrocracking at moderate pressure, a heavy part of the diesel fraction which is loaded with nitrogen and sulfur compounds which are the most difficult to hydrotreat. Therefore, a conventional hydrotreatment can be used to treat the remaining diesel fraction, and there is no need for costly investment. In addition, by treating this heavy part of the diesel in the process according to the invention, the hydrodesulfurization of the heavy fraction is carried out with at the same time an improvement in its qualities (cetane index higher than that which would have been obtained by severe hydrotreatment alone) .

The fillers which can also be used have a temperature T ₉₅ of at most 470 ° C, or better still of at most 450 ° C, or better understood in the range 390-430 ° C, T ₉₅ representing the temperature of the point 95% obtained by simulated distillation (ASTM-D28 87).

Mention may be made, as fillers, of light vacuum distillates, a light fraction of a conventional vacuum gas oil (VGO) (for example the lightest half), heavy atmospheric gas oils (HGO), mixtures of said fillers or mixtures said charges with at least one diesel fraction, for example coming from the distillation of crude oil or from an FCC unit (catalytic cracking).

The hydrocarbon feedstocks treated generally have sulfur contents of 0.2 to 4% by mass and nitrogen contents of 100-3500 ppm by mass. They are therefore generally hydrotreated before being hydrocracked so as to lower the contents of organic nitrogen (that is to say of nitrogen forming part of organic molecules) below 80 ppm, or better still of 50 ppm and preferably below 10 ppm, and the contents of organic sulfur, (that is to say sulfur forming part of organic molecules) below 200 ppm and preferably below 50 ppm. These hydrotreated fillers (called clean) can then be subjected to hydrocracking.

The hydrotreatment conditions are generally:

pressure of 5-25 MPa, preferably with a partial hydrogen pressure greater than 70 bars and at most 100 bars, preferably at least 80 bars or even at least 85 bars,

temperature of at least 320 ° C, in general at least 350 ° C and at most 450 ° C most often, or even at most 430 ° C,

H2 / load volume ratio of at least 100 Nl / I, and most often between 100-2000 Nl / l or even 300-2000 Nl / i, hourly volume speed of 0.1-1 Oh ^"1 , preferably 0.15-7h ^{" 1} , and advantageously 0.05-4h ^"1 .

The conversion carried out in the hydrotreatment is generally at least 10% by volume and less than 40% in product boiling below 350 ° C.

Hydrotreatment can be carried out either in the hydrocracking reactor and in at least one bed preceding the first bed of the hydrocracking catalyst, in the direction of flow of the charge, or in an independent reactor preceding the reaction reactor. hydrocracking. There is or there is no intermediate separation of the gases regenerated by the hydrotreatment. The first mode (same reactor) without intermediate separation is preferred. Also included in the process is an embodiment in which the hydrotreating is carried out in the refinery very upstream from the hydrocracking, intermediate treatments may also be carried out.

The clean charge is, at least in part, in the presence of hydrogen brought into contact with at least one hydrocracking catalyst under the following operating conditions:

- partial hydrogen pressure greater than 70 bars and at most 100 bars, reference at least 80 bars or at least 85 bars,

- temperature at least 320 ° C, in general at least 350 ° C and at most 450 ° C most often, or even at most 430 ° C,

- H2 / load volume ratio of at least 200NI / NI and most often between 300-2000NI / NI.

- Hourly volume speed 0.15-7h ^"1 , preferably 0.05-4h ^{" 1} .

The process can operate with or without recycling the distillation residue from the hydrocracking effluent (fraction not converted). When there is recycling, it is carried out towards the hydrocracking reactor if it is separated from that of hydrotreating for example or also into the feed entering the reactor where hydrotreatment and hydrocracking are carried out.

Under these conditions, at the level of the process as a whole, the conversion into products boiling below 350 ° C. is at least 80% by volume, and more generally at least 90% by volume, or even at least 95% volume. Hydrotreatment catalysts

Conventional catalysts can be used, which contain at least one amorphous support and at least one hydro-dehydrogenating element (generally at least one element from groups VIB and VIII non-noble, and most often at least one element from group VIB and at least a non-noble element of group VIII).

Very advantageously, a hydrotreating catalyst comprises at least one matrix, at least one hydro-dehydrogenating element chosen from the group formed by the elements of group VIB and group VIII of the periodic table, optionally at least one promoter element deposited on the catalyst and chosen from the group formed by phosphorus, boron and silicon, optionally at least one element from group VIIA (chlorine, fluorine preferred), and optionally at least one element from group VIIB (preferred manganese), optionally at minus one element from the VB group (preferred niobium).

In general, the hydrotreating catalyst contains:

- 5-40% by weight of at least one non-noble element of groups VIB and VIII (% oxide)

- 0-20% of at least one promoter element chosen from phosphorus, boron, silicon (% oxide), preferably 0.1-20%; advantageously boron and / or silicon are present, and optionally phosphorus. - 0-20% of at least one element from the VIIB group (manganese for example)

- 0-20% of at least one element from group VIIA (fluorine, chlorine for example)

- 0-60% of at least one element of the VB group (niobium for example)

- 0.1-95% of at least one matrix, and preferably alumina

Preferably, this catalyst contains boron and / or silicon as a promoter element, optionally with phosphorus as another promoter element. The contents of boron, silicon, phosphorus are then 0.1-20%, preferably 0.1-15%, even more advantageously 0.1-10%.

The matrices which can be used alone or as a mixture are, by way of nonlimiting example, alumina, halogenated alumina, silica, silica-alumina, clays (for example among natural clays such as kaolin or bentonite), magnesia, titanium oxide, boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates, carbon, aluminates. We prefer to use matrices containing alumina, in all these known forms skilled in the art, and even more preferably aluminas, for example gamma alumina.

The role of hydro-dehydrogenating function is preferably fulfilled by at least one metal or compound of metal from the non-noble groups VIII and VI preferably chosen from molybdenum, tungsten, nickel and cobalt. Preferably, this role is ensured by the combination of at least one element from the Vlll group (Ni, Co) with at least one element from the VIB group (Mo, W).

This catalyst may advantageously contain phosphorus; in fact, it is known in the prior art that this compound provides two advantages to hydrotreatment catalysts: ease of preparation during in particular the impregnation of nickel and molybdenum solutions, and better hydrogenation activity. In a preferred catalyst, the total concentration of metal oxides of groups VI and Vlll is between 5 and 40% by weight and preferably between 7 and 30% and the weight ratio expressed as metal oxide between metal (or metals) of the group VIB on metal (or metals) of group V111 is preferably between 20 and 1.25 and even more preferred between 10 and 2. The concentration of phosphorus oxide P2O5 will be less than 15% by weight and preferably 10% by weight.

Another preferred hydrotreating catalyst which contains boron and / or silicon (and preferably boron and silicon) generally contains in% by weight relative to the total mass of the catalyst at least one metal chosen from the following groups and with the following contents:

3 to 60%, preferably 3 to 45% and even more preferably 3 to 30% of at least one metal from group VIB and optionally,

- 0 to 30%, preferably from 0 to 25% and even more preferably from 0 to 20% of at least one metal from group VIII, the catalyst additionally containing at least one support chosen from the following groups with the following contents: - 0 to 99%, advantageously 0.1 to 99%, preferably from 10 to 98% and even more preferably from 15 to 95% of at least one amorphous or poorly crystallized matrix, the said catalyst being characterized in that it also contains, - 0.1 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to 10% boron and / or 0.1 to 20%, preferably 0.1 to 15 % and even more preferably from 0.1 to 10% of silicon. and optionally, 0 to 20%, preferably from 0.1 to 15% and even more preferably from 0.1 to 10% of phosphorus, and optionally still,

- 0 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to 10% of at least one element chosen from the group VIIA, preferably fluorine. Generally, the formulas having the following atomic ratios are preferred:

- an atomic ratio of metal from group III / metals from group VIB of between 0 and 1,

- an atomic ratio B / metals of group VIB of between 0.01 and 3,

- an atomic ratio Si / metals of group VIB between 0.01 and 1.5, - an atomic ratio P / metals of group VIB between 0.01 and 1,

- an atomic ratio of group VllA / metals of group VIB of 0.01 to 2.

Such a catalyst has a higher activity in the hydrogenation of aromatic hydrocarbons and in hydrodenitrogenation and in hydrodesulfurization than the catalytic formulas without boron and / or silicon, and also has a higher activity and selectivity in hydrocracking than the catalytic formulas known in the art. prior art. The catalyst with boron and silicon is particularly interesting. Without wishing to be bound by any theory, it seems that this particularly high activity of the catalysts with boron and silicon is due to the strengthening of the acidity of the catalyst by the joint presence of boron and silicon on the matrix which induces on the one hand an improvement in the hydrogenating, hydrodesulfurizing, hydrodeazotant properties and on the other hand an improvement in the hydrocracking activity compared to the catalysts usually used in hydroconversion hydrorefining reactions.

The preferred catalysts are the NiMo and / or NiW catalysts on alumina, also the NiMo and / or NiW catalysts on alumina doped with at least one element included in the group of atoms formed by phosphorus, boron, silicon and fluorine, or the NiMo and / or NiW catalysts on silica-alumina, or on silica- alumina-titanium oxide doped or not with at least one element included in the group of atoms formed by phosphorus, boron, fluorine and silicon.

Another particularly interesting type of catalyst (in particular in improved activity) in hydrotreatment, contains a partially amorphous Y zeolite which will be described later in the hydrocracking catalysts.

Prior to injection of the feedstock, the catalysts used in the process according to the present invention are preferably subjected beforehand to a sulphurization treatment making it possible to transform, at least in part, the metallic species into sulphide before they are brought into contact with the load to be processed. This activation treatment by sulfurization is well known to those skilled in the art and can be carried out by any method already described in the literature either in situ, that is to say in the reactor, or ex situ.

A conventional sulfurization method well known to those skilled in the art consists in heating in the presence of hydrogen sulfide (pure or for example under a flow of a hydrogen / hydrogen sulfide mixture) to a temperature between 150 and 800 ° C., preferably between 250 and 600 ° C, generally in a reaction zone with a crossed bed.

Hydrocracking catalysts A preferred catalyst comprises at least one Y zeolite, at least one matrix and a hydro-dehydrogenating function. Optionally, it can also contain at least one element chosen from boron, phosphorus and silicon, at least one element from G VIIA (chlorine, fluorine for example), at least one element from group VIIB (manganese for example), minus one element of the VB group (niobium for example).

The catalyst contains at least one porous or poorly crystallized mineral matrix of the oxide type. Mention may be made, by way of nonlimiting example, of aluminas, silicas, silica-aluminas, aluminates, alumina-boron oxide, magnesia, silica-magnesia, zirconia, titanium oxide, l clay, alone or in mixture.

The hydro-dehydrogenating function is generally provided by at least one element from group VI B (for example molybdenum and / or tungsten) and / or at least one element from group Vll1 which is non-noble (for example cobalt and / or nickel) of the classification of the elements. A preferred catalyst essentially contains at least one group VI metal, and / or at least one non-noble group VIII metal, zeolite Y and alumina. An even more preferred catalyst essentially contains nickel, molybdenum, a Y zeolite and alumina.

The catalyst optionally contains at least one element chosen from the group formed by boron, silicon and phosphorus. Advantageously, the catalyst optionally contains at least one element of group VIIA, preferably chlorine and fluorine, optionally at least one element of group VIIB (manganese for example), optionally at least one element of group VB (niobium for example ).

Boron, silicon and / or phosphorus can be in the matrix, the zeolite or are preferably deposited on the catalyst and then mainly located on the matrix. A preferred catalyst contains B and / or Si as a promoter element deposited with preferably in addition to the promoter phosphorus. The amounts introduced are 0.1-20% by weight of catalyst calculated as oxide.

The element introduced, and in particular the silicon, mainly located on the matrix of the support can be characterized by techniques such as the Castaing microprobe (distribution profile of the various elements), transmission electron microscopy coupled with an X-ray analysis of the components of the catalysts, or else by establishing a distribution map of the elements present in the catalyst by electron microprobe.

In general, a preferred hydrocracking catalyst advantageously contains:

- 0.1-80% by weight of zeolite Y

- 0.1-40% by weight of at least one element from groups VIB and Vlll (% oxide)

- 0.1-99.8% matrix weight (% oxide)

- 0-20% by weight of at least one element chosen from the group formed by P, B, Si (% oxide), preferably 0.1-20% - 0-20% weight of at least one element from the group VIIA, preferably 0.1-20%

- 0-20% by weight of at least one element from group VIIB, preferably 0.1-20%

- 0-60% by weight of at least one element from the VB group, preferably 0.1-60% ιυ

With regard to silicon, in the 0-20% range only the added silicon is counted and not that of the zeolite.

The zeolite can optionally be doped with metallic elements such as, for example, the metals of the rare earth family, in particular lanthanum and cerium, or noble or non-noble metals of group VIII, such as platinum, palladium, ruthenium, rhodium, iridium, iron and other metals such as manganese, zinc, magnesium.

Different Y zeolites can be used.

A particularly advantageous acidic H-Y zeolite is characterized by different specifications: an overall molar ratio Siθ2 Al2θ3 of between approximately 6 and 70 and preferably between approximately 12 and 50: a sodium content of less than 0.15

% weight determined on the zeolite calcined at 1100 ° C; a crystalline parameter has

-10 the elementary mesh between 24.58 x 10 ^" ^ m and 24.24 x 10 m and so

-10 -10 preferred between 24.38 x 10 m and 24.26 x 10 m; a CNa capacity for taking up sodium ions, expressed in grams of Na per 100 grams of modified zeolite, neutralized then calcined, greater than about 0.85; a specific surface area determined by the BET method greater than approximately 400 m ^ / g and preferably greater than 550 m ² / g, a water vapor adsorption capacity at 25 ° C. for a partial pressure of 2.6 torrs (i.e. 34.6 MPa), greater than approximately 6%, and advantageously, the zeolite has a porous distribution, determined by physisorption of nitrogen, comprising between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in pores with a diameter between

-10 -10

20 x 10 m and 80 x 10 m, and between 5 and 45% and preferably between 5 and 40% of the total pore volume of the zeolite contained in pores with a diameter greater than 80 x 10 m and generally less than 1000 x 10 m, the rest of the pore volume

-10 being contained in the pores of diameter less than 20 x 10 m.

A preferred catalyst using this type of zeolite contains a matrix, at least one dealuminated Y zeolite and having a crystalline parameter comprised between 2,424 nm and 2,455 nm preferably between 2,426 and 2,438 nm, a higher overall Si0 ₂ / Al ₂ 0 ₃ molar ratio. to 8, a content of cations of alkaline earth or alkali metals and / or cations of. rare earths such that the atomic ratio (nx M ^{n +} ) / AI is less than 0.8, preferably less than 0.5 or even 0.1, a specific surface area determined by the BET method greater than 400 m ² / g of preferably greater than 550m ² / g, and a water adsorption capacity at 25 ° C for a P / Po value of 0.2, greater than 6% by weight, said catalyst also comprising at least one hydro-dehydrogenating metal, and silicon deposited on the catalyst.

In an advantageous embodiment according to the invention, a catalyst comprising a partially amorphous Y zeolite is used for hydrocracking.

The term “partially amorphous Y zeolite” means a solid having:

I a peak rate which is less than 0.40 preferably less than about 0.30

-H / a crystalline fraction expressed relative to a reference zeolite Y in sodium form (Na) which is less than about 60%, preferably less than about 50%, and determined by X-ray diffraction.

Preferably, the partially amorphous, solid Y zeolites used in the composition of the catalyst according to the invention exhibit at least one (and preferably all) of the following other characteristics:

iii / an overall Si / Ai ratio greater than 15, preferably greater than 20 and less than 150,

-iv / a Si / Ai ^l structure ratio greater than or equal to the overall Si / Ai ratio,

a pore volume at least equal to 0.20 ml / g of solid, a fraction of which, between 8% and 50%, consists of pores having a diameter of at least 5 nm (nanometer), ie 50 Å.

-M \ I a specific surface of 210-800 m ² / g, preferably 250-750 m ² / g and advantage 300-600 m ² / g

Peak rates and crystal fractions are determined by X-ray diffraction using a procedure derived from ASTM D3906-97 "Determination of Relative X-ray Diffraction Intensifies of Faujasite-Type-Containing Materials". This method may be referred to for the general conditions of application of the procedure and, in particular, for the preparation of samples and references.

A diffractogram is composed of the lines characteristic of the crystallized fraction of the sample and of a background, mainly caused by the diffusion of the amorphous or microcrystalline fraction of the sample (a weak diffusion signal is linked to the apparatus, air , sample holder, etc.) The peak rate of a zeolite is the ratio, in a predefined angular zone (typically 8 to 40 ° 2Θ when using the K radiation of copper, 1 = 0.154 nm), from the area of the lines of the zeolite (peaks) to the global area of the diffractogram (peaks + background). This peak / (peak + bottom) ratio is proportional to the amount of zeolite crystallized in the material. To estimate the crystalline fraction of a Y zeolite sample, the peak rate of the sample will be compared to that of a reference considered to be 100% crystallized (NaY for example). The peak rate of a perfectly crystallized NaY zeolite is of the order of 0.55 to 0.60.

The peak rate of a conventional USY zeolite is from 0.45 to 0.55, its crystalline fraction relative to a perfectly crystallized NaY is from 80 to 95%. The. rate of peaks of the solid which is the subject of the present invention is less than 0.4 and preferably less than 0.35. Its crystalline fraction is therefore less than 70%, preferably less than 60%.

The partially amorphous zeolites are prepared according to the techniques generally used for dealumination, from commercially available Y zeolites, that is to say which generally have high crystallinities (at least 80%). More generally, it will be possible to start from zeolites having a crystalline fraction of at least 60%, or at least 70%.

The Y zeolites generally used in hydrocracking catalysts are manufactured by modification of commercially available Na-Y zeolite. This modification leads to so-called stabilized, ultra-stabilized or dealuminated zeolites. This modification is carried out by at least one of the dealumination techniques, and for example the hydrothermal treatment, the acid attack. Preferably, this modification is carried out by combination of three types of operations known to those skilled in the art: hydrothermal treatment, ion exchange and acid attack.

Another particularly interesting zeolite is a globally non-dealuminated zeolite which is very acidic.

By globally non dealuminated zeolite is understood a Y zeolite (structural type FAU, faujasite) according to the nomenclature developed in "Atlas of zeolites structure types", WM Meier, DH Oison and Ch. Baerlocher, 4 ^th revised Edition 1996, Elsevier. The crystalline parameter of this zeolite may have decreased by extraction of the aluminum from the structure or frame during the preparation, but the ratio Overall SiO ₂ / Al ₂ 0 ₃ did not change because the aluminum was not extracted chemically. Such a globally non dealuminated zeolite therefore has a silicon and aluminum composition expressed by the overall SiO ₂ / Al ₂ 0 ₃ ratio equivalent to the starting non dealuminated Y zeolite. The values of the parameters (SiO ₂ / AI ₂ 0 ₃ ratio and crystalline parameter are given below.). This globally non dealuminated Y zeolite can be in the hydrogen form or be at least partially exchanged with metal cations, for example using cations, alkaline earth metals and / or rare earth metal cations with atomic number 57 to 71 inclusive. We prefer a zeolite devoid of rare earths and alkaline earths, the same for the catalyst.

The zeolite Y which is not globally dealuminated generally has a crystalline parameter greater than 2.438 nm, an overall SiO ₂ / AI ₂ O ₃ ratio less than 8, a molar SiO ₂ / AI ₂ O ₃ molar ratio less than 21 and greater than the SiO ratio ₂ / AI ₂ O ₃ overall. The generally non dealuminated zeolite can be obtained by any treatment which does not extract the aluminum from the sample, such as, for example, treatment with steam, treatment with SiCI, etc.

Another type of catalyst advantageous for hydrocracking contains an acidic amorphous oxide matrix of the alumina type doped with phosphorus, a zeolite Y not dealuminated overall and very acidic and optionally at least one element of group VIIA and in particular fluorine.

The invention is not limited to the cited and preferred Y zeolites, but other types of Y zeolites can be used in this process.

Prior to injection of the feed, the catalyst is subjected to a sulfurization treatment making it possible to transform, at least in part, the metallic species into sulphide before they are brought into contact with the feed to be treated. This activation treatment by sulfurization is well known to those skilled in the art and can be carried out by any method already described in the literature either in situ, that is to say in the reactor, or ex situ.

A conventional sulfurization method well known to those skilled in the art consists in heating in the presence of hydrogen sulfide (pure or for example under a flow of a hydrogen / hydrogen sulfide mixture) to a temperature between 150 and 800 ° C., preferably between 250 and 600 ° C, generally in a reaction zone with a crossed bed. When the hydrotreatment and hydrocracking catalysts are in the same reactor or in two reactors without intermediate separation, they are sulfurized at the same time.

Separation and products

The liquid effluent from hydrocracking is then distilled so as to separate a naphtha cut, a diesel cut, possibly a kerosene cut (which can sometimes be included at least partially in the diesel cut), the LPG light gases. There remains a liquid residue which can advantageously be recycled in the process after purging generally.

It is obvious that the hydrogen has also been previously separated from the liquid effluent, which could later be stripped before being distilled.

Unexpectedly, it has been found that with the process according to the invention, diesels of very good qualities are obtained directly, meeting the specifications and without any additional treatment (severe hydrodesulfurization, hydrogenations, etc.) being necessary to improve. his qualities.

Thus, the method makes it possible to directly produce a diesel having a 95% volume distillation point less than 360 ° C, and generally this point is at most 350 ° C or even at most 340 ° C, having a sulfur content at most 50 ppm, and generally at most 10 ppm, having a cetane number of at least 52 and most generally of at least 54 and preferably having a polyaromatic content of at most 6% by weight and generally at most 1%, and preferably a pour point of less than -10 ° C, and preferably an aromatic content of less than 15% by weight.

A good quality kerosene is also produced in this process having a smoke point greater than 20 mm, preferably greater than 22 mm, and having a sulfur content less than 50 ppm, preferably less than 10 ppm. The kerosene may possibly be at least partially sent into the diesel pool, depending on the needs of the operator.

It is quite remarkable to obtain such qualities of diesel without further treatment and for a much lower investment than a high pressure hydrocracking, while allowing the recovery of "light" charges from the refinery such that the current gas oils which, because of the strictness of the specifications, will find themselves either in excess or must undergo severe subsequent treatments.

With regard to the yields of middle distillate (kerosene + diesel) produced, they are at least 60% volume, most often at least 65% volume. The other products formed are light gases LPG (represent at most 10% by weight and more generally at most 5% by weight) and naphtha (generally at least 20% by volume).

The figures

The process will be described briefly below with reference to the figures. FIG. 1 represents an embodiment of the hydrocracking process at moderate pressure. Figures 2B, 2C, 3, 4 illustrate an integration of this process in a catalytic cracking installation, Figure 2A showing the prior art.

The hydrocracking process at moderate pressure is shown diagrammatically in FIG. 1. The charge to be treated enters via line 1, it is in this figure, added to the recycling of the hydrocracking residue through line 2 and of hydrogen via line 3. It passes through a heat exchanger 4 mixed with the recycled hydrogen brought in via line 5, then through a heater 6 before being introduced into the hydrocracking reactor (or zone) 7 at moderate pressure possibly containing upstream the hydrotreating zone or zones.

The reactor 7 contains at least one catalytic bed 8 of at least one hydrocracking catalyst. Preferably, it can contain upstream of the first bed 8 at least one hydrotreating catalyst. The liquid effluent from the reactor and leaving via line 9 passes through the exchanger 4 and then in a gas-liquid separator 10 separating the hydrogen which is recycled through line 5 to the hydrocracking reactor 7.

The separated liquid effluent leaving via line 11 is preferably sent to a stripper 12 which separates naphtha and light gases via line 13 and a resulting effluent leaving through line 14 is distilled in the atmospheric distillation column 15. This arrangement schematically illustrates an embodiment of the distillation. Any other arrangement known to those skilled in the art leading to the separation of the same products is also suitable. There is thus obtained a diesel discharged through line 16 and a residue recycled through line 2 to the hydrocracking reactor, apart from purging through line 17. Optionally, kerosene is obtained.

Thus, the product separation zone separates a hydrocracking residue with a boiling point higher than at least 535 ° C., and comprises a pipe for purging said residue and optionally a pipe for recycling said purged residue towards the zone or the reactor. hydrocracking.

To facilitate reading of the figure, the compressors and utilities which are known to those skilled in the art have not been shown.

The hydrocracking process described here can very advantageously be integrated into the refinery at the level of a catalytic cracking process (in general FCC: catalytic cracking in a fluidized bed).

The result is a combined process producing both good quality diesel and naphtha (for the production of gasoline).

The invention also relates to an installation for implementing the method described above. This installation comprises: a column for the distillation of a hydrocarbon feedstock making it possible to separate at least a fraction having a temperature T ₅ of between 250 ° C and 400 ° C and a temperature T ₉₅ of at most 470 ° C, - at least a hydrotreating zone of said feed or of said fraction, at least one hydrocracking zone at moderate pressure of said fraction, said pressure being greater than 70 bars and at most 100 bars, at least one zone for separating products making it possible to obtain a diesel having a 95% distillation point of less than 360 ° C., a sulfur content of at most 50 ppm and a cetane number greater than 51.

In a more particular embodiment shown below, the installation comprises: an atmospheric distillation column of said gross charge to separate at least naphtha, diesel and an atmospheric residue, a vacuum distillation column to treat said atmospheric residue, and to separate at least a vacuum distillate fraction and a vacuum residue, installation in which the atmospheric distillation column or the vacuum distillation column comprises at least one pipe recovering a fraction having a temperature T ₅ of between 250 ° C and 400 ° C and a temperature T ₉₅ of at most 470 ° C, the installation also includes at least one zone for hydrotreating said fraction followed by at least one zone d hydrocracking at moderate pressure and at least one product separation zone and making it possible to obtain a diesel having a 95% distillation point below 360 ° C., a sulfur content of at most 50 ppm and an index of cetane greater than 51.

To better understand the invention and its interest, it has been shown diagrammatically in FIG. 2A of the prior art and FIG. 2B in the invention, and the method of the invention will be described using these figures.

Figure 2A shows a current installation. The crude hydrocarbon feed (or crude petroleum) which arrives via line 20 is distilled in the atmospheric column 21. There is separated one (by this term generally also includes at least one) naphtha fraction (line 22), a jet fuel fraction ( line 23), a diesel fraction (line 24).

The atmospheric residue leaving via line 25 is vacuum distilled in the vacuum distillation column 26. There is separated a vacuum distillate fraction (line 27) and there remains a vacuum residue (line 38).

Said vacuum distillate is sent to a catalytic cracking unit 28 (generally in a fluidized bed) which by this process produces, inter alia, naphtha discharged through line 29, a fraction of highly aromatic diesel type (light cycle oil LCO) evacuated via line 30, and a "slurry" or residue leaving via line 31.

Most often, the vacuum residue is treated in a viscoreduction unit 39, which produces, inter alia, naphtha (line 40) and diesel (line 41) which are of low quality. The viscoreduction residue (line 42) can only be used as fuel as well as the slurry, part of the LCO can be used to flux this fuel.

FIG. 2B shows the process and the installation according to the invention, combining hydrocracking at moderate pressure and catalytic cracking.

We recognize the pins of Figure 2A, and not to burden the diagram we have not shown the visbreaker, but it is generally present in the installation. The installation according to the invention (FIG. 2B) comprises, in addition to that of the prior art (FIG. 2A), the hydrocracking unit 32 at moderate pressure which receives a light fraction resulting from the vacuum distillation brought into the driving 33.

Unit 32 includes the hydrocracking reactor (s) or zone (s) at moderate pressure and the associated separations making it possible to exit, inter alia, via a line 34 a high quality diesel, through line 35 a naphtha and via a line 36 the purging of the hydrocracking residue. Usually, the unit 32 also includes a hydrotreating zone before hydrocracking.

The hydrocracking residue can at least partly be sent to catalytic cracking (unit 28) but without this being compulsory. The purge of the hydrocracking process is advantageously sent to unit 28.

The recycling of the purged residue has not been shown here to the hydrocracking zone, or to the hydrocracking reactor also comprising the hydrotreating zone. Recycling and passage of the purge in FCC can be done separately or together.

In the context of the process according to the invention, as illustrated for example in FIG. 2B with an FCC, during atmospheric distillation the cutting point for the distilled diesel cut (line 24) is chosen by the operator.

The atmospheric residue, which therefore contains at least part of the heavy atmospheric diesel, is vacuum distilled into at least one light fraction (distillate) and at least one heavy fraction (distillate), and there remains a vacuum residue.

Said light fraction to be treated by hydrocracking has a temperature T ₅ which is between 250 and 400 ° C and a temperature T ₉₅ which is at most 470 ° C. It is a light vacuum diesel fuel (LVGO). The final boiling point is chosen by the operator according to the column at his disposal and according to the recovery desired by the products. Said light fraction has the other characteristics of the hydrocarbon feedstocks treated by the process according to the invention and described above.

In general, this light vacuum distillate treatment by moderate pressure hydrocracking can be implemented when the production and / or quality of diesel want to be increased, regardless of the type of treatment reserved for the distillate (s) heavy (s) and residue from vacuum distillation. ιy

In another embodiment, instead of fractionating the atmospheric residue into light and heavy fraction (s) by vacuum distillation, and sending the light fraction (s) into hydrocracking, we take (if the type of column allows) the heavy diesel cut having substantially the same temperatures T ₅ and T ₉₅ at atmospheric distillation. This mode is illustrated in FIG. 2C where the references of the preceding figures are recognized and where the charge to the unit 32 is an atmospheric diesel fuel supplied by the pipe 37. In this figure, the pipe 33 no longer exists. In this case, the atmospheric residue boiling over the heavy diesel is distilled under vacuum, the vacuum distillation also produces a residue and at least one fraction distilled under vacuum here called heavy.

The vacuum distillation residue (line 38) which generally has a temperature T ₅ of at least 535 ° C, preferably at least 550 ° C, or even at least 565 ° C or 570 ° C, can be subjected for example to a viscoreduction (shown in FIG. 1) or to a hydroconversion of residue or a coking.

In all cases, at least one so-called heavy vacuum distillate fraction, situated between the light fraction having a temperature T ₉₅ of at most 470 ° C., and the vacuum residue, is subjected to catalytic cracking.

FIG. 3 represents an installation and a process in which the heavy fraction resulting from vacuum distillation and which is subjected to catalytic cracking, is, before said cracking, subjected to hydrotreatment in a zone 43. The references of the previous figures are repeated here.

This hydrotreatment before the FCC takes place in the presence of at least one amorphous catalyst. All conventional hydrotreatment catalysts can be used. Mention will be made of the catalysts containing at least one element from the non-noble group VIII (Co, Ni for example) and at least one element from the group VIB (Mo, W for example) deposited on a support preferably based on alumina or silica -alumina. The particularity of this step lies in its operating conditions: a partial hydrogen pressure between 25 and 90 bars, preferably less than 85 bars, or even less than 80 bars, or even less than 70 bars, and a temperature of 350- 450 ° C, preferably 370-430 ° C adjusted so as to maintain a conversion of at least 10% and preferably less than 40% in products boiling below 350 ° C and preferably 15-30%. There is thus produced a naphtha (line 44) and a diesel (line 45) but of medium quality and intended either for domestic fuel use or for the diesel pool.

The hydrotreated effluent then passes through the catalytic cracking unit 28.

In FIG. 4, a contribution of heavy diesel fraction has been schematically represented in unit 32 where hydrocracking is carried out at moderate pressure. In this embodiment, it is obtained by atmospheric distillation, in addition to the naphtha (line 22), kerosene (line 23) cuts, a light diesel fraction LGO (line 46) and a heavy diesel fraction HGO (line 47). This heavy diesel fraction is sent to unit 32 where it will undergo hydrotreatment then hydrocracking at moderate pressure.

Thus, the present application describes a process for producing diesel and naphtha, the production of diesel being carried out by a hydrocracking process at moderate pressure as set out above, and the production of naphtha being obtained essentially by catalytic cracking. . Preferably, the hydrocracking purge is sent to catalytic cracking.

A preferred embodiment of this type of method has been described, but other embodiments, other arrangements of the methods for achieving the same goal are possible.

To illustrate the advantage of the invention, the production of a current refining scheme, of a current scheme for producing diesel to specifications, is quantified below.

2005 and a diagram according to the invention. In the diagram of Figure 2A (current diagram specifications 2000) for a treatment of 10 Mt / year of North Sea crude, we have (diagram 1):

- naphtha 3.17 Mt / year - carburetor 0.73 Mt / year

- Diesel 2.32 Mt / year

- Domestic fuel 1.5 Mt / year

- Fuel from a residue 565 ° C + subject to a viscoreduction: 1, 42 Mt / year of fuel 40 est (diluted by LCO and including slurry)

Diesel has a cetane number of 49 and a sulfur content of 2,100 ppm. To meet specifications (cetane 51 and sulfur 350 ppm), it must undergo conventional desulfurization. Without change in the refinery diagram, but with diesel qualities to the 2005 specifications (95% point taken at 340 ° C), we have (diagram 2):

- naphtha 3.32 Mt / year

- jet fuel cut 0.82 Mt / year - diesel 2.13 Mt / year

- Domestic fuel 1.36 Mt / year

- Fuel 40cst from the residue 565 ° C + 1, 43 Mt / year

Diesel has a cetane number of only 48 and must therefore undergo extremely severe hydrodesulfurization and hydrogenation which it is not possible to carry out in current units.

The naphtha pool would have a sulfur content of 270 ppm by mass, which would require severe subsequent treatments to reduce it to 10-50 ppm by mass. Also, to avoid costly investments, the naphtha fraction from the FCC will be treated separately in severe hydrodesulfurization, with the drawback of lowering the octane number. The other naphtha fractions (for example from the visbreaker, from the distillation of crude ...) will be sent to reforming and possibly an isomerization unit after hydrotreatment.

The addition to scheme 2 preceding hydrotreatment before catalytic cracking (as shown in Figure 3 but under hydrocracking) has the consequence (scheme 3): - naphtha 3.06 Mt / year

- jet fuel 0.84 Mt / year

- diesel 2.57 Mt / year

- domestic fuel 1.40 Mt / year

- fuel 40 is from the residue 565 ° C + 1.36 Mt / year

Cetane from diesel remains at about 48. FCC naphtha has a sulfur content of 15 ppm, and in the naphtha pool the sulfur content can then be lowered to as low as about 5.5 ppm, without loss of sensitive octane.

With a preferred scheme 4 according to the invention (FIG. 3) including hydrocracking at moderate pressure, one obtains (scheme 4): - naphtha 2.90 Mt / year

- carburetor 0.86 Mt / year

- diesel 2.82 Mt / year

- domestic fuel 1, 44 Mt / year - fuel 40 is 1.34 Mt / year

In this case, vacuum distillation separates a light fraction 350-410 ° C, a heavy fraction 410-565 ° C and a residue 565 ° C +.

In hydrocracking, the conversion is almost complete (≥ 98%), the H2 consumption of 1.85% w / w, the pressure is 90 bars ppH. diesel obtained: 95% point 340 ° C flash point> 60 ° C cetane 56 sulfur <10 ppm polyaromatic <1% wt

The comparison of these figures shows the excellent quality of the diesel obtained by a scheme according to the invention, a quality never achieved directly before.

Compared to a conventional hydrocracking, for the same product qualities, it was possible to achieve a saving of 50 bars in hydrogen pressure, which considerably reduces the costs.

In terms of productivity, the quantities of the products are similar to those in diagram 3, but on the other hand the comparison with diagram 2 (current refinery upgraded to 2005 specifications) shows significant gains, for the same quantity of crude oil in: diesel + 32.4% kerosene 4.9%

We were thus able to adjust the diesel / naphtha balance towards more high-quality diesel, while somewhat reducing the production of 40cst fuel (-6.3%), thus adapting the refinery to market needs. In addition, since the FCC unit does not work at full capacity, the operator can very advantageously introduce an additional charge capable of being treated with FCC (such as an atmospheric residue). This addition will preferably be carried out in the feed entering the vacuum distillation column (dotted lines in FIG. 3).

Claims

claims

1. A method for producing a diesel having a 95% distillation point of less than 360 ° C., a sulfur content of at most 50 ppm and a cetane number greater than 51, said method treating hydrocarbon feedstocks having a temperature

T ₅ between 250 and 400 ° C and a temperature T ₉₅ of at most 470 ° C, said process comprising a hydrotreatment producing an effluent having an organic nitrogen content below 10 ppm then a hydrocracking at moderate pressure with a catalyst hydrocracking comprising at least one zeolite Y, at least one matrix and a hydro-dehydrogenating function, said hydrocracking operating under a partial hydrogen pressure greater than 70 bars and at most 100 bars, at a temperature of at least 320 ° C, with a volume ratio H ₂ / load of at least 200 NI / NI, an hourly volume speed of 0.15-7h ^"1 , the process carrying out a conversion of at least 80% volume and the effluent liquid obtained by hydrocracking being distilled to separate the diesel.

2. Method according to claim 1 wherein the conversion is at least 95% volume.

3. Method according to one of the preceding claims wherein the hydrocarbon feedstock has a temperature T ₉₅ between 390-430 ° C.

4. Method according to one of the preceding claims wherein the hydrocarbon feedstock has a temperature T ₅ between 320 and 370 ° C.

5. Method according to one of the preceding claims in which the hydrocarbon feedstock is chosen from the group formed by heavy atmospheric gas oils or light fractions of gas oils under vacuum, distillates under light vacuum, mixtures of said charges together, mixtures said charges with a diesel fraction.

6. Method according to one of the preceding claims wherein the hydrotreating and hydrocracking are carried out in the same reactor and without intermediate separation of the gases produced by the hydrotreatment.

7. Method according to one of the preceding claims wherein the hydrocracking residue is recycled after purging in the process.

8. Method according to one of the preceding claims, in which the diesel obtained has a 95% point of at most 340 ° C, a sulfur content of at most 10 ppm and a cetane number of at least 54.

9. Method according to one of the preceding claims, in which the hydrotreatment catalyst comprises:

- 5-40% by weight of at least one non-noble element of groups VIB and Vlll (% oxide)

- 0-20% of at least one promoter element chosen from phosphorus, boron, silicon (% oxide).

- 0-20% of at least one element of the VIIB group

- 0% of the VIIA group element

- 0-60% of at least one element of the VB group

- 0.1-95% of at least one matrix, and the hydrocracking catalyst comprises:

- 0.1-80% by weight of zeolite Y

- 0.1-40% by weight of at least one element from groups VIB and Vlll (% oxide)

- 0.1-99.8% matrix weight (% oxide)

- 0-20% by weight of at least one element chosen from the group formed by P, B, Si (% oxide)

- 0% element weight of group VIIA

- 0-20% by weight of at least one element from group VIIB

- 0-60% by weight of at least one element from the VB group.

10. Method according to one of the preceding claims wherein the feed having a temperature T ₅ of 250 to 400 ° C and a temperature T ₉₅ of at most

470 ° C is a light fraction from the vacuum distillation of an atmospheric residue.

11. The method of claim 10 wherein the vacuum distillation also produces a vacuum residue with a boiling point of at least 535 ° C and at least one heavy fraction located between said light fraction and the residue, said heavy fraction being subjected, at least in part, to catalytic cracking.

12. Method according to one of the preceding claims, in which the hydrocarbon feedstock to be treated by hydrocracking at moderate pressure is a heavy atmospheric gas oil obtained from atmospheric distillation, the atmospheric residue boiling above said gas oil is distilled under vacuum, and at least one fraction distilled under heavy vacuum is subjected to a catalytic cracking and a residue under vacuum is obtained.

13. Method according to one of the preceding claims wherein the purging of hydrocracking at moderate pressure is subjected to catalytic cracking.

14. Method according to one of the preceding claims wherein, before being subjected to catalytic cracking, the distillate fraction under heavy vacuum is hydrotreated under a partial hydrogen pressure of 25-90 bars, at a temperature of 350-430 ° C, with a conversion of at least 10% and less than 40% volume into products boiling below 350 ° C.

15. Method according to one of the preceding claims in which the vacuum residue is subjected to a treatment by a process chosen from the group formed by viscoreduction processes, residue hydroconversion processes, coking processes.

16. Process for treating crude hydrocarbon feed comprising the following steps: - atmospheric distillation of the crude hydrocarbon feed, producing at least one naphtha fraction, at least one jet fuel fraction, at least one diesel fraction and one atmospheric residue vacuum distillation of the residue atmospheric to separate at least one light distillate fraction, at least one heavy distillate fraction and a residue under vacuum treatment of said light fraction by the process according to one of claims 1 to 15 with production of a hydrocracking residue

- catalytic cracking of at least one heavy fraction, optionally containing at least part of the hydrocracking residue.

17. Process for treating crude hydrocarbon feed comprising the following steps:

- atmospheric distillation of the crude hydrocarbon feed, producing at least one naphtha fraction, at least one jet fuel fraction, at least a diesel fraction, a heavy atmospheric diesel cut and an atmospheric residue

- vacuum distillation of the atmospheric residue to separate at least a heavy distillate fraction and a vacuum residue

- Treatment of said heavy diesel cut by the method according to one of claims 1 to 15 with production of a hydrocracking residue catalytic cracking of at least one heavy distillate fraction, optionally added with at least part of the residue d hydrocracking.

18. The method of claim 16. wherein the atmospheric distillation also produces a heavy atmospheric diesel fraction, said fraction also being treated by the method according to one of claims 1 to 15 with said light fraction.

19. Method according to one of claims 16 to 18 further comprising treating the residue under vacuum by viscoreduction.

20. Installation for the production of diesel comprising:

a column for the distillation of a hydrocarbon feedstock making it possible to separate at least one fraction having a temperature T ₅ of between

250 ° C and 400 ° C and a temperature T ₉₅ of at most 470 ° C,

- at least one hydrotreating zone of said feed or of said fraction,

- at least one hydrocracking zone at moderate pressure of said fraction, said pressure being greater than 70 bars and at most 100 bars, - at least one zone for separating the products making it possible to obtain a diesel having a distillation point 95% below 360 ° C, a sulfur content of at most 50 ppm and a cetane number greater than 51.

21. Installation for the production of diesel according to claim 20, from a crude hydrocarbon feed comprising:

a column for the atmospheric distillation of said gross charge in order to separate at least naphtha, diesel and an atmospheric residue,

a vacuum distillation column for treating said atmospheric residue, and for separating at least one vacuum distillate fraction and one residue under vacuum, - installation in which the atmospheric distillation column or the vacuum distillation column comprises at least one pipe recovering a fraction having a temperature T ₅ of between 250 ° C and 400 ° C and a temperature T ₉₅ of at most 470 ° C , the installation also includes at least one hydrotreating zone for said fraction followed by at least one hydrocracking zone at moderate pressure, and at least one zone for separating the products and making it possible to obtain a diesel having a 95% distillation point below 360 ° C, a sulfur content of at most 50 ppm and a cetane number greater than 51.

22. Installation according to one of claims 20 or 21 comprising a hydrotreating zone before the hydrocracking zone and located in the same reactor.

23. Installation according to one of claims 20 to 22 in which the product separation zone separates a hydrocracking residue with a boiling point greater than at least 535 ° C, and comprises a pipe for purging said residue and optionally a line for recycling said purged residue to the hydrocracking zone or reactor.

24. Installation according to one of claims 20 to 23 comprising a catalytic cracking zone for treating at least a fraction of vacuum distillate located between the fraction having a temperature T ₉₅ of at most 470 ° C and the residue under vacuum.

25. Installation according to one of claims 20 to 24 comprising a pipe bringing the purge to the catalytic cracking zone.

26. Installation according to one of claims 20 to 25 comprising a hydrotreating zone before the catalytic cracking zone.