WO2023110650A1

WO2023110650A1 - Hydrocracking catalyst comprising a specific zeolite y and an mfi-structure zeolite for producing a steam-cracking feedstock

Info

Publication number: WO2023110650A1
Application number: PCT/EP2022/085088
Authority: WO
Inventors: Mathias Dodin; Antoine Daudin
Original assignee: IFP Energies Nouvelles
Priority date: 2021-12-16
Filing date: 2022-12-09
Publication date: 2023-06-22
Also published as: FR3130641A1

Abstract

The invention relates to a hydrocracking catalyst comprising at least one hydro-dehydrogenating element selected from the group formed of the non-noble elements from groups VIB and VIII of the periodic table taken alone or in a mixture, and a support comprising at least one porous inorganic matrix, an MPI-structure zeolite and a zeolite Y having an initial lattice constant a0 of the unit cell greater than 24.32 Å and a Bronsted acidity greater than 200 micromol/g.

Description

HYDROCRACKING CATALYST COMPRISING A

SPECIFIC Y ZEOLITH AND AN MFI-TYPE ZEOLITH FOR THE PRODUCTION OF A STEAM CRACKING CHARGE

Field of the invention

The invention relates to a hydrocracking catalyst based on USY zeolite and MFI structural type zeolite as well as its use for the production of a light cut comprising the light naphtha cut and C1 -C4 gases by hydrocracking of petroleum cuts such as vacuum distillates and gas oil. This type of process is used in particular in schemes intended for the conversion of hydrocarbon feedstocks for the production of petrochemical intermediates and gasoline fuels.

Hydrocracking catalysts are generally classified on the basis of the nature of their acid function, in particular catalysts comprising an amorphous acid function of silica alumina type and catalysts comprising a zeolite cracking function such as Y zeolite or beta zeolite.

Hydrocracking catalysts are also classified according to the major product sought when used in a hydrocracking process, the two major products being middle distillates and naphtha.

By naphtha cut is meant a cut that can have boiling points between that of hydrocarbon compounds having 5 carbon atoms per molecule (or 68°C boiling point) up to 175°C and includes the gasoline cut.

By light naphtha cut is meant the petroleum fraction comprising compounds comprising hydrocarbons with 5 carbon atoms up to compounds having a boiling point below 80°C.

The light naphtha fraction (C5-80°C) as well as the gases (C1 -C4) produced constitute a charge potentially recoverable by steam cracking.

There is a strong demand for recoverable cuts in petrochemicals. This is the reason why refiners have been focusing for several years on hydrocracking catalysts that are selective towards light cuts and in particular cuts having a point boiling point below 80°C for their recovery in a steam cracker for the production of petrochemical intermediates such as olefins (ethylene, propylene) and aromatics (benzene, toluene, xylene).

It is known to use catalysts based on FAU type zeolite to produce a naphtha cut.

Patent application WO1 1067258 (Shell) describes the preparation of an FAU zeolite having a lattice parameter of between 24.42 and 24.52 Angstroms (Å), a silica to alumina (SAR) molar ratio of between 10 and 15 , and a surface between 910 and 1020 m2/g. the family teaches that the catalyst comprising this zeolite is particularly selective towards the naphtha cut when it is used in a process for converting hydrocarbon cuts.

Patent application WO040487988 (Shell) describes a hydrocracking process using a catalyst comprising a Y zeolite having a low lattice parameter of between 24, 10 and 24.40 Angstroms (Å), a silica to alumina (SAR) molar ratio greater than 12 and preferably between 20 and 100 and a BET specific surface greater than 850 m2/g and a micropore volume greater than 0.28 ml/g. WO040487988 teaches that zeolites having a low lattice parameter are known to be selective towards the middle distillate cut but less active than zeolites having a higher lattice parameter. The catalysts comprising the zeolites with a low lattice parameter according to the invention of WO040487988 nevertheless make it possible to obtain the high activity combined with a good selectivity in middle distillates.

While attempting to develop a new catalyst for selective hydrocracking towards light cuts having a boiling point below 80° C., the applicant has discovered, surprisingly, that a catalyst comprising at least one hydro-dehydrogenating element chosen from the group formed by the non-noble elements of group VIB and group VIII of the periodic table, and a support comprising at least one porous mineral matrix, a zeolite of structural type MFI and a zeolite Y having an initial crystalline parameter aO of the lattice elemental greater than 24.32 Å, and a Bronsted acidity greater than 200 micromole/g makes it possible to obtain both improved activity and selectivity towards said light cut having a boiling point less than 80°C (including the light naphtha cut and gas), in particular with respect to the catalysts of the state of the art. Object of the invention

More specifically, the present invention relates to a selective hydrocracking catalyst towards light cuts having a boiling point below 80° C., comprising at least one hydro-dehydrogenating element chosen from the group formed by the elements of group VIB and non-noble group VIII taken alone or as a mixture of the periodic table, and a support comprising at least one porous mineral matrix, a zeolite of structural type MFI and a Y zeolite having an initial crystalline parameter aO of the unit cell greater than 24.32 Â and a Bronsted acidity greater than 200 micromole/g.

Another object of the present invention is a process for hydrocracking a hydrocarbon charge in the presence of said catalyst.

An advantage of the present invention is to provide a hydrocracking catalyst making it possible to obtain improved selectivity towards the light cut having a boiling point below 80° C. when said catalyst is used in a hydrocracking process according to the invention, compared to catalysts of the state of the art and in particular compared to catalysts comprising only a zeolite Y.

According to an advantageous embodiment, the catalyst according to the invention comprises a Y zeolite having specific characteristics in combination with a zeolite with structural code MFI.

An advantage of the advantageous embodiment of the present invention is to provide a hydrocracking catalyst comprising said Y zeolite having specific characteristics, in particular, a Y zeolite having an initial crystalline parameter aO of the unit cell of between 24.32 and 24.40 Å, and very preferably between 24.34 Å and 24.38 Å, and a Bronsted acidity between 300 and 500 micromole/g, very preferably between 320 and 500 micromole/g and so even more preferably between between 325 and 425 micromole/g, a micropore volume determined by nitrogen adsorption greater than 0.28 ml/g and preferably greater than 0.285 ml/g and advantageously less than 0.34 ml/g and a specific surface area measured by nitrogen physisorption according to the BET method of between 700 and 1000 m2/g, and a zeolite with structural code MFI not only making it possible to obtain improved selectivity towards the light cut having a point of boiling below 80°C when said catalyst is used in a hydrocracking process according to the invention, but also an improved activity compared to the catalysts of the prior art.

In the present invention, the selectivity of hydrocracking catalysts for the production of light cuts having a boiling point below 80°C is determined during a catalytic test and corresponds to the fraction, in weight percentage, of the product boiling in the range of the light cut having a boiling point below 80°C, i.e. between the boiling temperature of gases at C1 and molecules having a boiling point of 80°C with respect to the total mass of product leaving the process.

In the present invention, the converting activity of hydrocracking catalysts for the production of light cuts having a boiling point below 80°C is determined during a catalytic test by comparing the conversion to products having a lower boiling point at 175°C for a fixed temperature. The higher the conversion, the more active the catalyst. This increase in activity makes it possible, for example, to limit the energy consumption of the process and to increase the duration of the cycle of use of the catalyst, or even to treat less reactive feedstocks without modifying the capacity and the process diagram.

Throughout the rest of the text, specific surface area means the B.E.T (SBET) specific surface area determined by nitrogen adsorption in accordance with the ASTM 4365-19 standard established from the BRUNAUER-EMMETT-TELLER method described in the periodical “ The Journal of American Society”, 60, 309, (1938). Texture analysis by nitrogen adsorption also makes it possible to determine the micropore volume, i.e. the volume of pores whose opening is less than 2 nm. Before analysis, the zeolite powder is activated at 500°C for 5 hours.

Similarly, the volume of mesopores is determined by nitrogen adsorption. Throughout the remainder of the text, “micropores” means pores with an opening of less than 2 nm, and “mesopores” means pores with an opening of more than 2 nm.

Throughout the rest of the text, the Bronsted acidity of the Y and MFI zeolite is measured by adsorption and subsequent thermodesorption of pyridine followed by infrared spectroscopy (FTIR). This method is conventionally used to characterize acidic solids such as Y zeolites as described in the periodical CA Emeis “Journal of Catalysis”, 141, 347, (1993). Before analysis, the zeolite powder is compacted in the form of a pellet 16 mm in diameter and is activated under a high vacuum at 450°C. The introduction of the pyridine in the gaseous phase in contact with the activated pellet as well as the step of thermodesorption are carried out at 150°C. The pyridinium ion concentration detected by FTIR after thermodesorption at 150° C. corresponds to the Bronsted acidity of the zeolite and is expressed in micromoles/g.

Within the meaning of the present invention, the various embodiments presented can be used alone or in combination with each other, without limitation of combination.

Within the meaning of the present invention, the various ranges of parameters for a given stage such as the pressure ranges and the temperature ranges can be used alone or in combination. For example, within the meaning of the present invention, a preferred range of pressure values can be combined with a more preferred range of temperature values.

In the rest of the text, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief D.R. Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification, and group VIB to the metals of column 6.

In the rest of the text, the expressions "between ... and ..." and "between .... and ..." are equivalent and mean that the limit values of the interval are included in the range of values described. If this was not the case and the limit values were not included in the range described, such precision will be provided by the present invention.

Detailed description of the invention

The hydro/dehydrogenating function

In accordance with the invention, the catalyst comprises at least one hydro-dehydrogenating element chosen from the group formed by the non-noble group VIB and group VIII elements of the periodic table, taken alone or as a mixture.

Preferably, the elements of group VIII are chosen from iron, cobalt, nickel, taken alone or as a mixture, and preferably from nickel and cobalt. Preferably, the elements of group VIB are chosen from tungsten and molybdenum, taken alone or as a mixture. The following combinations of metals are preferred: nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, cobalt-tungsten, and very preferably: nickel- molybdenum, nickel-tungsten. It is also possible to use combinations of three metals such as, for example, nickel-cobalt-molybdenum.

The catalyst content of group VIII element is advantageously between 0.5 and 8% by weight of oxide relative to the total weight of said catalyst, preferably between 0.5 and 6% by weight of oxide and in a manner very preferably between 1.0 and 4% by weight of oxide. The catalyst content of group VIB element is advantageously between 1 and 30% by weight of oxide relative to the total weight of said catalyst, preferably between 2 and 25% by weight of oxide, very preferably between 5 and 20% by weight oxide, and even more preferably between 5 and 16% by weight oxide.

Preferably, the catalyst used according to the invention can also contain a promoter element chosen from phosphorus, boron, silicon, very preferably phosphorus. When the catalyst contains phosphorus, the phosphorus content is advantageously between 0.5 and 10% by weight of P2O5 oxide relative to the total weight of said catalyst, preferably between 1 and 6% by weight of P2O5 oxide. and more preferably between 1 and 4% by weight of P2O5 oxide.

The support

The catalyst according to the invention comprises a support which comprises and is preferably constituted by at least one porous mineral matrix, a zeolite of structural type MFI and a Y zeolite, preferably a dealuminated zeolite USY, said Y zeolite having an initial crystalline parameter unit cell aO greater than 24.32 Å, and a Bronsted acidity greater than 200 micromole/g.

The porous mineral matrix used in the catalyst support, also called binder, advantageously consists of at least one refractory oxide, preferably chosen from the group formed by alumina, silica-alumina, clay, oxide titanium, boron oxide and zirconia, taken alone or as a mixture. Preferably, the porous mineral matrix is chosen from alumina and silica-alumina, taken alone or as a mixture. More preferably, the porous mineral matrix is alumina. The alumina can advantageously be in any of its forms known to those skilled in the art. Very preferably, the alumina is gamma alumina, for example boehmite. Preferably, said support comprises from 15 to 55% by weight of binder, preferably from 25% to 50% by weight, and very preferably between 25% and 40% by weight, relative to the total weight of said support.

According to the invention, the support comprises a Y zeolite having an initial crystalline parameter aO of the unit cell greater than 24.32 Å.

Preferably, the initial crystalline parameter aO of the unit cell of the Y zeolite used is less than 24.55 Å, preferably between 24.32 and 24.50 Å, preferably between 24.32 and 24.45 Å , preferably between 24.32 and 24.40 Å, and very preferably between 24.34 Å and 24.38 Å.

The given initial crystalline parameter aO of the unit cell of the Y zeolite is the value of the initial crystalline parameter aO of the Y zeolite used in the synthesis of the catalyst according to the invention.

The initial crystalline parameter aO of the unit cell of the Y zeolite is measured by X-ray diffraction according to standard ASTM 03942-80.

According to the invention, said Y zeolite has a Bronsted acidity greater than 200 micromole/g, preferably between 250 and 500 micromole/g, preferably between 300 and 500 micromole/g, very preferably between 320 and 500 micromole/g and even more preferably between between 325 and 425 micromole/g.

Preferably, said Y zeolite has a specific surface area measured by nitrogen physisorption according to the B.E.T. between 700 and 1000 m2/g, preferably between 750 and 950 m2/g, and more preferably between 800 and 950 m2/g.

Preferably, said Y zeolite has a micropore volume determined by nitrogen adsorption greater than 0.26 ml/g, preferably greater than 0.28 ml/g and preferably greater than 0.285 ml/g and advantageously less than 0. .34ml/g.

Preferably, said Y zeolite has a silica to alumina (SAR) molar ratio of between 5 and 50 and preferably between 5 and 20 and preferably greater than 5 and less than 12.

Preferably, said Y zeolite has a mesoporous volume greater than 0.12 ml/g, preferably greater than 0.16 ml/g and preferably between 0.18 and 0.24 ml/g. In a particularly preferred embodiment, said Y zeolite has an initial crystalline parameter aO of the unit cell of between 24.32 and 24.40 Å, and very preferably between 24.34 Å and 24.38 Å, and a Bronsted acidity of between 300 and 500 micromole/g, very preferably between 320 and 500 micromole/g and even more preferably between between 325 and 425 micromole/g, a micropore volume determined by adsorption of higher nitrogen to 0.28 ml/g and preferably greater than 0.285 ml/g and advantageously less than 0.34 ml/g and a specific surface area measured by nitrogen physisorption according to the BET method of between 700 and 1000 m2/g.

In this case, the hydrocracking catalyst comprising said Y zeolite having specific characteristics, and a zeolite with structural code MFI not only makes it possible to obtain improved activity and selectivity towards the light cut having a boiling below 80° C. when said catalyst is used in a hydrocracking process according to the invention, but also an improved activity compared to the catalysts of the prior art comprising only a Y zeolite.

Preferably, said support has a content of Y zeolite, and preferably of USY dealuminated zeolite, of between 15 and 80% by weight relative to the total weight of said support, preferably between 20 and 75% by weight, and preferably between 40 at 70% weight.

Said zeolites are advantageously defined in the classification “Atlas of Zeolite Framework Types, 6th revised edition”, Ch. Baerlocher, L. B. Mc Cusker, D.H. Oison, 6th Edition, Elsevier, 2007, Elsevier".

According to a preferred embodiment of the invention, the zeolite Y, and preferably the dealuminated zeolite USY, having the particular characteristic defined above and suitable for the implementation of the catalyst support used in the process according to the invention is advantageously prepared from a Y zeolite of structural type FAU preferably having an overall Si/Al atomic ratio after synthesis of between 2.3 and 2.8 and advantageously being in the NaY form after synthesis. Said Y zeolite of structural type FAU advantageously undergoes a stage of one or more ion exchanges before undergoing the dealumination stage. The ion exchange(s) make it possible to partially or totally replace the alkaline cations belonging to groups IA and IIA of the periodic table present in the cationic position in the crudely synthesized FAU structural type Y zeolite with NH4+ cations and preferably cations Na-i- by NH4+ cations. By partial or total exchange of alkaline cations by NH4+ cations is meant the exchange of 80 to 100%, preferably 85 to 99.5% and more preferably 88 to 99%, of said alkaline cations by NH4+ cations. At the end of the ion exchange step(s), the remaining quantity of alkaline cations, and preferably the remaining quantity of Na+ cations, in the Y zeolite, relative to the quantity of alkaline cations, preferably Na+, initially present in the Y zeolite, is advantageously between 0 and 20%, preferably between 0.5 and 15% and more preferably between 1.0 and 12%.

Preferably, this step implements several ion exchanges with a solution containing at least one ammonium salt chosen from ammonium chlorate, sulfate, nitrate, phosphate, or acetate salts, so as to eliminate at least in part, the alkaline cations and preferably the Na+ cations present in the zeolite. Preferably, the ammonium salt is ammonium nitrate NH4NO3.

Thus, the remaining content of alkaline cations and preferably of Na+ cations in the Y zeolite at the end of the ion exchange(s) stage is preferably such that the molar ratio of the alkaline cation/aluminum and of preferably the Na/Al molar ratio is between 0:1 and 0:1, preferably between 0:1 and 0.005:1, and more preferably between 0:1 and 0.008:1.

The desired alkali/aluminum cation ratio, preferably Na/Al, is obtained by adjusting the NH4+ concentration of the ion exchange solution, the ion exchange temperature and the number of ion exchanges. The concentration of the ion exchange solution in NH4+ advantageously varies between 0.01 and 12 mol.L-1, and preferably between 1.00 and 10 mol.L-1. The temperature of the ion exchange step is advantageously between 20 and 100°C, preferably between 60 and 95°C, more preferably between 60 and 90°C, more preferably between 60 and 85°C and even more preferably between 60 and 80°C. The number of ion exchanges advantageously varies between 1 and 10 and preferably between 1 and 4.

Said Y zeolite, preferably of structural type FAU, obtained can then undergo a dealumination treatment step. Said dealumination step can advantageously be carried out by any method known to those skilled in the art. Preferably, the dealumination is carried out by a heat treatment possibly in the presence of water vapor (or steaming according to the Anglo-Saxon terminology) and/or by one or more acid attacks advantageously carried out by treatment with an aqueous solution of acid mineral or organic. Preferably, the dealumination step implements a heat treatment followed by one or more acid attacks, or only one or more acid attacks.

Preferably, the heat treatment, optionally in the presence of steam, to which said Y zeolite is subjected is carried out at a temperature of between 200 and 900° C., preferably between 300 and 900° C., even more preferably between 400 and 750°C. The duration of said heat treatment is advantageously greater than or equal to 0.5 h, preferably between 0.5 h and 24 h, and very preferably between 1 h and 12 h. In the case where the heat treatment is carried out in the presence of water, the volume percentage of water vapor during the heat treatment is advantageously between 5 and 100%, preferably between 20 and 100%, very preferably between 40 and 100%. The volume fraction other than the water vapor that may be present is made up of air. The flow rate of gas formed of water vapor and possibly air is advantageously between 0.2 L.h-1 .g-1 and 10 L.h-1 .g-1 of the Y zeolite.

The heat treatment makes it possible to extract the aluminum atoms from the framework of the Y zeolite while maintaining the overall Si/Al atomic ratio of the treated zeolite unchanged.

The heat treatment step in the presence of steam can advantageously be repeated as many times as necessary to obtain the dealuminated Y zeolite USY suitable for the implementation of the catalyst support used in the process according to the invention. and having a unit cell crystal parameter aO greater than 24.32 Å.

The heat treatment step, possibly in the presence of steam, is advantageously followed by an acid attack step. Said acid attack makes it possible to partially or totally eliminate the aluminum debris resulting from the heat treatment step in the presence of water vapor and which partially block the porosity of the dealuminated zeolite; the acid attack therefore unblocks the porosity of the dealuminated zeolite.

The acid attack can advantageously be carried out by suspending the Y zeolite, which has optionally previously undergone heat treatment, in an aqueous solution containing a mineral or organic acid. The mineral acid can be nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid or boric acid. The organic acid can be formic acid, acetic acid, oxalic acid, tartaric acid, maleic acid, malonic acid, malic acid, lactic acid, or any other acid organic soluble in the water. The concentration of the mineral or organic acid solution in the solution advantageously varies between 0.01 and 2.0 mol.L-1, and preferably between 0.5 and 1.0 mol.L-1. The temperature of the acid attack step is advantageously between 20 and 100°C, preferably between 60 and 95°C, more preferably between 60 and 90°C and more preferably between 60 and 80°C. The duration of the acid attack is advantageously between 5 minutes and 8 hours, preferably between 30 minutes and 4 hours, and more preferably between 1 hour and 2 hours.

At the end of the heat treatment step or steps, optionally in the presence of steam, and optionally of the acid attack step, the process for modifying said Y zeolite advantageously comprises a step of at least one partial exchange or total of the alkaline cations and preferably of the Na+ cations still present in the cationic position in the Y zeolite. The ion exchange stage is carried out in a manner similar to the ion exchange stage described above.

At the end of the heat treatment step or steps, optionally in the presence of steam, and optionally of the acid attack step and optionally of the partial or total exchange step of the alkaline cations and preferably of the cations Na-i-, the process for modifying said Y zeolite may comprise a calcination step. Said calcination makes it possible to eliminate the organic species present within the porosity of the zeolite, for example those introduced by the acid attack stage or by the stage of partial or total exchange of alkaline cations. In addition, said calcination step makes it possible to generate the protonated form of the Y zeolite and to confer an acidity on it with a view to its applications.

The calcination can advantageously be carried out in a muffle furnace or in a tube furnace, under dry air or under an inert atmosphere, in a licked bed or in a traversed bed. The calcination temperature is advantageously between 200 and 800°C, preferably between 450 and 600°C, and more preferably between 500 and 550°C. The duration of the calcination plateau is advantageously between 1 and 20 hours, preferably between 6 and 15 hours, and more preferably between 8 and 12 hours.

Thus, said Y zeolite obtained and preferably said dealuminated USY zeolite has an initial crystalline parameter aO of the unit cell greater than 24.32 Å, and a Bronsted acidity greater than 200 micromole/g. In accordance with the invention, the support also comprises a zeolite of structural type MFI.

MFI structural type zeolites are crystallized microporous solids and have been described in the literature (G. T. Kokotailo, S.L. Lawton, D.H. Olson, W.M. Meier, Nature, vol. 272, p. 437-438, 1978; D.H. Olson, G. T Kokotailo, S.L. -242, 1990). The crystalline structure of these materials is described in the documents “Collection of simulated XRD powder patterns for zeolites”, Ed. M.M.J. Treacy and J.B. Higgins, Fifth Revised Edition, 2007, p. 280-281 and “Atlas of zeolite framework types”, C. Baerlocher, L.B. McCusker, D.H. Olson, Sixth Revised Edition, 2007, p. 212-213.

The processes for preparing zeolites with structural code MFI are also described in said documents.

Said zeolite with structural code MFI has a chemical composition expressed on an anhydrous basis, in terms of moles of oxides, defined by the following general formula: (96-a) XO2: a/2 Y2O3: a/2 M2/nO, in which X represents at least one tetravalent element, Y represents at least one trivalent element, M is at least one alkali metal and/or an alkaline earth metal of valence n, and x < 27.

X is preferentially chosen from silicon, germanium, titanium and the mixture of at least two of these tetravalent elements, very preferentially X is silicon and Y is preferentially chosen from aluminum, boron, iron, indium and gallium, very preferably Y is aluminum. M is preferentially chosen from lithium, sodium, potassium, calcium, magnesium and the mixture of at least two of these metals and very preferentially M is sodium. Preferably, X represents silicon, said zeolite with structural code MFI according to the invention is then an entirely silicic solid when the element Y is absent from the composition of said zeolite with structural code MFI. It is also advantageous to use as element X a mixture of several elements, in particular a mixture of silicon with another element X chosen from germanium and titanium, preferably germanium. Thus, when silicon is present in a mixture with another element X, said zeolite with structural code MFI according to the invention is then a crystallized metallosilicate having an X-ray diffraction pattern identical to that described in "Collection of simulated XRD powder patterns for zeolites”, Ed. MMJ Treacy and JB Higgins, Fifth Revised Edition, 2007, p. 280-281 when in its form calcined. Even more preferably and in the presence of an element Y, X being silicon and Y being aluminium: said zeolite with structural code MFI according to the invention is then an aluminosilicate. Preferably, said zeolite with structural code MFI according to the invention is in the aluminosilicate form.

Preferably, the zeolite with structural code MFI is ZSM-5.

Preferably, the molar ratio of the number of silicon atoms to the number of Si/Al aluminum atoms is less than 100, preferably less than 70, very preferably less than 50.

The zeolite with structural code MFI entering into the composition of the catalyst support according to the invention is advantageously exchanged by at least one treatment with a solution of at least one ammonium salt so as to obtain the ammonium form of the zeolite with code structural code MFI which, once calcined, leads to the acid form (H+) of said zeolite with structural code MFI. This exchange step can be carried out at any step in the preparation of the catalyst, that is to say after the step for preparing the zeolite with structural code MFI, after the step for shaping the zeolite Y and zeolite with structural code MFI with a porous mineral binder, or else after the step of introducing the hydro-dehydrogenating phase.

Said zeolite with structural code MFI entering into the composition of the catalyst support used in the process according to the invention can be, at least in part, in the acid form, that is to say in the H+ form.

The zeolite with structural code MFI used in the support according to the invention advantageously has a specific surface area measured by nitrogen physisorption according to the B.E.T. between 300 and 600 m2/g, preferably between 350 and 550 m2/g, and more preferably between 400 and 500 m2/g.

Said MFI zeolite has a Bronsted acidity greater than 100 pmol/g of zeolite and preferably between 100 and 450 pmol/g, preferably between 110 and 250 pmol/g and very preferably between 130-230 pmol/g .

Preferably, the support advantageously has a content of zeolite with structural code MFI of between 2 and 40%, preferably between 5 and 35%, and more preferably between 7 and 30% by weight relative to the total weight of said support. Preferably, the weight ratio of said Y zeolite to said zeolite with structural code MFI and preferably ZSM-5 in the catalyst is between 1 and 40.

Preferably, the weight ratio of said zeolite Y to said zeolite with structural code MFI and preferably ZSM-5 in the catalyst is between 1 and 20, and preferably between 1.2 and 15, and preferably between 1. 5 and 8.

This weight ratio is calculated from the dry masses of the zeolites, i.e. the masses of the zeolites corrected for their water content determined by measuring the Loss On Ignition at 1000°C. (dry mass)

Preferably, the support comprises USY zeolite and a zeolite with structural code MFI, it preferably consists of:

- 15 to 80%, preferably from 20 to 75%, and preferably from 40 to 70%, by weight relative to the total weight of said support of a Y zeolite, preferably a dealuminated USY zeolite, having a initial crystalline parameter aO of the unit cell greater than 24.32 Å;

- 2 and 40%, preferably between 4 and 35%, and preferably between 7 and 30% by weight relative to the total weight of said support of a zeolite with structural code MFI; And

- from 5 to 83% by weight, preferably between 15% to 50% by weight, and very preferably between 20% and 40% by weight relative to the total weight of said support of at least one porous mineral matrix.

Preferably, the catalyst has a Y zeolite content of between 7 and 78% by weight relative to the total weight of said catalyst.

Preferably, said catalyst has a content of zeolite with structural code MFI, of between 2 and 39% by weight relative to the total weight of said catalyst.

Preferably, said catalyst has a content of at least one porous mineral matrix of between 4 and 81% by weight relative to the total weight of said catalyst.

The hydrocracking catalyst advantageously having a Y/MFI ratio included in these ranges not only makes it possible to obtain improved selectivity towards the light cut having a boiling point below 80° C. when said catalyst is used in a hydrocracking process according to the invention, but also an improved activity compared to the catalysts of the state of the art.

Preparation of the catalyst

The catalyst is advantageously prepared according to the conventional methods used in the prior art.

In particular, the catalyst is prepared according to a preparation process comprising:

- a support preparation step comprising:

• the mixture of at least one porous mineral matrix with a Y zeolite having an initial crystalline parameter aO of the unit cell greater than 24.32 Å and a Bronsted acidity greater than 200 micromole / g, with a zeolite of structural code MFI , the weight ratio of said zeolite Y to said zeolite with structural code MFI in the catalyst being advantageously between 1 and 40 and

• the shaping of said mixture;

- the introduction of at least one hydro-dehydrogenating element chosen from the group formed by the elements of group VIB of the periodic table, preferably nickel and cobalt, the non-noble elements of group VIII of the periodic table, preferably iron, cobalt, nickel, and mixtures thereof, and preferably nickel and cobalt, and mixtures thereof, on the support by:

• addition of at least one precursor of said element during shaping so as to introduce at least part of said element,

• impregnation of the support with at least one precursor of said element,

- optionally a drying and/or calcination step after the preparation of the support and/or the step of introducing at least one hydro-dehydrogenating element.

More particularly, the catalyst is prepared according to a preparation process comprising the following steps: a) preparation of zeolite Y, preferably dealuminated zeolite USY having the specific crystallographic characteristic claimed according to the process described above, b) preparation of zeolite of structural code MFI, c) mixing with a porous mineral matrix and shaping to obtain the support, d) introduction of at least one hydro-dehydrogenating element on the support by at least one of the following methods:

• impregnation of the support with at least one precursor of said hydro-dehydrogenating element,

Optionally drying and/or calcining of the products obtained at the end of each of the preparation steps a) or b) or c) or d).

The support can advantageously be shaped by any technique known to those skilled in the art. The shaping can be carried out, for example, by extrusion, by pelleting, by the oil-drop coagulation method, by granulation on a turntable or by any other method well known to those skilled in the art.

The support is preferably shaped in the form of grains of different shapes and sizes. They are generally used in the form of cylindrical or multi-lobed extrudates such as three-lobed, four-lobed or poly-lobed straight or twisted shapes, but can optionally be manufactured and used in the form of crushed powders, tablets, rings, balls, wheels. However, it is advantageous for the catalyst to be in the form of extrudates with a diameter of between 0.5 and 5 mm and more particularly between 0.7 and 3 mm and even more particularly between 1.0 and 2.5 mm. The shapes are cylindrical (which may or may not be hollow), twisted cylindrical, multilobed (2, 3, 4 or 5 lobes for example), rings. Any other shape can be used.

One of the preferred shaping methods consists in co-kneading said zeolites with the binder, preferably alumina, in the form of a wet gel for a few tens of minutes, preferably between 10 and 40 minutes, then passing the paste thus obtained through a die to form extrudates with a diameter preferably between 0.5 and 5 mm.

According to another of the preferred shaping methods, said zeolites can be introduced during the synthesis of the porous mineral matrix. For example, according to this preferred mode of the present invention, said zeolites Y and of structural code MFI are added during the synthesis of a porous mineral matrix, such as for example a silico-aluminum matrix: in this case, said zeolites can be advantageously added to a mixture composed of an alumina compound in an acid medium with a totally soluble silica compound.

The introduction of elements from group VIB and/or VIII may optionally take place during the shaping step, by adding at least one compound of said element, so as to introduce at least a part of said element.

The introduction of at least one hydro-dehydrogenating element can advantageously be accompanied by that of at least one promoter element chosen from phosphorus, boron, silicon and preferably phosphorus and optionally by the introduction of an element from the group VI IA and/or VB. The shaped solid is optionally dried at a temperature of between 60 and 250° C. and optionally calcined at a temperature of 250 to 800° C. for a period of between 30 minutes and 6 hours.

The step of introducing at least one hydro-dehydrogenating element is advantageously carried out by a method well known to those skilled in the art, in particular by one or more operations of impregnation of the shaped and calcined or dried support, and preferably calcined, with a solution containing the precursors of the elements of group VIB and/or VIII, optionally the precursor of at least one promoter element and optionally the precursor of at least one element of group VI IA and/or of group VB.

Preferably, said step d) is carried out by a method of dry impregnation with a solution containing the precursors of the hydro/dehydrogenating function, that is to say elements from group VIB and/or VIII, optionally followed a drying step and preferably without a calcining step.

In the case where the catalyst of the present invention contains a non-noble metal of group VIII, the metals of group VIII are preferably introduced by one or more operations of impregnation of the shaped and calcined support, after those of group VIB or at the same time as these.

The introduction of at least one hydro-dehydrogenating element can then optionally be followed by drying at a temperature between 60 and 250°C and optionally by calcination at a temperature between 250 and 800°C.

The sources of molybdenum and tungsten are advantageously chosen from oxides and hydroxides, molybdic and tungstic acids and their salts, in particular salts ammonium such as ammonium molybdate, ammonium heptamolybdate, ammonium tungstate, phosphomolybdic acid, phosphotungstic acid and their salts, silicomolybdic acid, silicotungstic acid and their salts. Preference is given to using ammonium oxides and salts such as ammonium molybdate, ammonium heptamolybdate and ammonium tungstate.

The sources of non-noble group VIII elements that can be used are well known to those skilled in the art. For example, for the non-noble metals, nitrates, sulphates, hydroxides, phosphates, halides such as for example chlorides, bromides and fluorides, carboxylates such as for example acetates and carbonates will be used.

The preferred source of phosphorus is orthophosphoric acid H3PO4, but its salts and esters such as ammonium phosphates are also suitable. Phosphorus can for example be introduced in the form of a mixture of phosphoric acid and a basic organic compound containing nitrogen such as ammonia, primary and secondary amines, cyclic amines, compounds of pyridine and quinoline family and compounds of the pyrrole family. Tungsto-phosphoric or tungsto-molybdic acids can be employed.

The phosphorus content is adjusted, without this limiting the scope of the invention, in such a way as to form a mixed compound in solution and/or on the support, for example tungsten-phosphorus or molybdenum-tungsten-phosphorus. These mixed compounds can be heteropolyanions. These compounds can be Anderson heteropolyanions, for example.

The source of boron can be boric acid, preferably orthoboric acid H3BO3, ammonium biborate or pentaborate, boron oxide, boric esters. Boron can for example be introduced in the form of a mixture of boric acid, hydrogen peroxide and a basic organic compound containing nitrogen such as ammonia, primary and secondary amines, cyclic amines, compounds of the pyridine and quinoline family and compounds of the pyrrole family. Boron can be introduced for example by a solution of boric acid in a water-alcohol mixture.

Many sources of silicon can be employed. Thus, it is possible to use ethyl orthosilicate Si(OEt)4, siloxanes, polysiloxanes, silicones, emulsions silicones, halide silicates such as ammonium fluorosilicate (NH4)2SiF6 or sodium fluorosilicate Na2SiF6. Silicomolybdic acid and its salts, silicotungstic acid and its salts can also be advantageously employed. The silicon can be added, for example, by impregnation with ethyl silicate in solution in a water-alcohol mixture. The silicon can be added, for example, by impregnation with a silicon compound of the silicone type or silicic acid suspended in water.

Sources of group VB elements that can be used are well known to those skilled in the art. For example, among the sources of niobium, it is possible to use oxides, such as diniobium pentoxide Nb2O5, niobic acid Nb2O5.H2O, niobium hydroxides and polyoxoniobates, niobium alkoxides of formula Nb(OR1)3 where R1 is an alkyl radical, niobium oxalate NbO(HC2O4)5, ammonium niobate. Preferably, niobium oxalate or ammonium niobate are used.

Sources of Group VI IA elements that can be used are well known to those skilled in the art. For example, fluoride anions can be introduced as hydrofluoric acid or its salts. These salts are formed with alkali metals, ammonium or an organic compound. In the latter case, the salt is advantageously formed in the reaction mixture by reaction between the organic compound and hydrofluoric acid. It is also possible to use hydrolyzable compounds that can release fluoride anions in water, such as ammonium fluorosilicate (NH4)2SiF6, silicon tetrafluoride SiF4 or sodium tetrafluoride Na2SiF6. The fluorine can be introduced, for example, by impregnation with an aqueous solution of hydrofluoric acid or ammonium fluoride.

Hydrocracking process

The catalyst according to the invention is then advantageously used in a hydrocracking process, in particular for the production of naphtha. The catalyst used in a hydrocracking process, such as the process according to the invention, can advantageously be in sulphide form. The non-noble group VIB and/or group VIII metals of said catalyst are therefore present in sulphide form.

The catalysts used in the processes according to the present invention are then advantageously subjected beforehand to a sulphidation treatment making it possible to convert, at least in part, the metallic species into sulphide form before they are brought into contact with the charge to be treated. This activation treatment by sulfurization is well known to 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 the catalyst in the presence of hydrogen sulphide (pure or for example under a flow of a mixture of hydrogen-hydrogen sulphide) at a temperature between 150 and 800 °C, preferably between 250 and 600°C, generally in a cross-bed reaction zone.

Another subject of the present invention also relates to a process for the hydrocracking of at least one hydrocarbon feedstock, preferably in liquid form, of which at least 50% by weight of the compounds have an initial boiling point above 300° C. and a final boiling point below 650°C, at a temperature between 200°C and 480°C, at a total pressure between 1 MPa and 25 MPa, with a volume ratio of hydrogen per volume of hydrocarbon charge between 80 and 5000 liters per liter and at an Hourly Volume Velocity (WH) defined by the ratio of the volume flow rate of hydrocarbon feedstock, preferably liquid, to the volume of catalyst loaded into the reactor of between 0.1 and 50 h- 1, in the presence of the catalyst according to the invention.

Advantageously, the catalyst according to the invention is used in the hydrocracking process according to the invention after a so-called pretreatment section containing one or more hydrotreatment catalyst(s) which may be any catalyst known to those skilled in the art. and which makes it possible to reduce the content of certain contaminants in the charge (see below) such as nitrogen, sulfur or metals. The operating conditions (WH, temperature, pressure, hydrogen flow rate, liquid, reaction configuration, etc.) of this so-called pretreatment section can be diverse and varied in accordance with the knowledge of those skilled in the art.

Expenses

Very varied feedstocks can be treated by the hydrocracking processes according to the invention. The feed used in the hydrocracking process according to the invention is a hydrocarbon feed, of which at least 50% by weight of the compounds have an initial boiling point above 300° C. and a final boiling point below 650° C. C, preferably of which at least 60% by weight, preferably of which at least 75% by weight and more preferably of which at least 80% by weight of the compounds, have an initial boiling point greater than 300°C and a final boil below 650°C. The feed is advantageously chosen from LCO (Light Cycle Oil, light gas oils from a catalytic cracking unit), atmospheric distillates, vacuum distillates such as, for example, gas oils from the direct distillation of crude oil or from conversion such as FCC, coker or visbreaking, feedstocks from aromatics extraction units from lube oil bases or from solvent dewaxing of lube oil bases, distillates from desulfurization processes or fixed bed or bubbling bed hydroconversion of RAT (atmospheric residues) and/or RSV (vacuum residues) and/or deasphalted oils, and deasphalted oils, paraffins from the Fischer-Tropsch process, taken alone or in combination. Mention may be made of fillers of renewable origin (such as vegetable oils, animal fats, hydrothermal conversion oil or lignocellulosic biomass pyrolysis oil) as well as plastic pyrolysis oils. The above list is not exhaustive. Said fillers preferably have a T5 boiling point above 300°C, preferably above 340°C, that is to say that 95% of the compounds present in the filler have a boiling point above 300°C , and preferably above 340°C.

The nitrogen content of the feeds treated in the processes according to the invention is advantageously greater than 500 ppm by weight, preferably between 500 and 10,000 ppm by weight, more preferably between 700 and 4,000 ppm by weight and even more preferably between 1,000 and 4000 ppmw. The sulfur content of the feeds treated in the processes according to the invention is advantageously between 0.01 and 5% by weight, preferably between 0.2 and 4% by weight and even more preferably between 0.5 and 3 % weight.

The filler may optionally contain metals. The cumulative nickel and vanadium content of the fillers treated in the processes according to the invention is preferably less than 1 ppm by weight.

The filler may optionally contain asphaltenes. The asphaltene content is generally less than 3000 ppm by weight, preferably less than 1000 ppm by weight, even more preferably less than 200 ppm by weight.

Advantageously, when the catalyst according to the invention is used after a hydrotreatment section as described above, the nitrogen, sulphur, metals or asphaltene content of the liquid injected into the process according to the invention using the catalyst according to the invention is reduced. Preferably, the organic nitrogen content of the feed treated in the hydrocracking process according to the invention is then comprised, after hydrotreatment, between 0 and 200 ppm, preferably between 0 and 50 ppm, and even more preferably between 0 and 30 ppm. The sulfur content is preferably less than 1000 ppm and that of asphaltene is preferably less than 200 ppm while the metal content (Ni or V) is less than 1 ppm.

The hydrocracking process according to the invention may comprise a fractionation step between the pretreatment of the charge and the hydrocracking reactor(s) using the catalyst according to the invention. In the preferred case where the hydrocracking process is carried out without fractionation (gas and liquid) between the pretreatment and the hydrocracking reactor(s) using the catalyst according to the invention, the nitrogen and the sulfur eliminated liquid after the pretreatment are injected in the form of NH3 and H2S into the reactor(s) containing the catalyst according to the invention.

In accordance with the invention, the process for hydrocracking said hydrocarbon feedstock according to the invention is carried out at a temperature of between 200° C. and 480° C., at a total pressure of between 1 MPa and 25 MPa, with a ratio volume of hydrogen per volume of hydrocarbon feedstock between 80 and 5000 liters per liter and at an Hourly Volume Rate (WH) defined by the ratio of the volume flow rate of hydrocarbon feedstock by the volume of catalyst loaded into the reactor between 0, 1 and 50 h-1.

Preferably, the hydrocracking process according to the invention operates in the presence of hydrogen, at a temperature of between 250 and 480° C., preferably between 320 and 450° C., very preferably between 330 and 435° C. , under a pressure of between 2 and 25 MPa, preferably between 3 and 20 MPa, at a space velocity of between 0.1 and 20 h-1, preferably 0.1 and 6 h-1, preferably between 0.2 and 3 h-1, and the quantity of hydrogen introduced is such that the volume ratio liter of hydrogen/liter of hydrocarbon is between 100 and 2000 L/L.

The process can be carried out in one stage or two stages depending on the level of conversion of the target feed, with or without recycling of the unconverted fraction. The catalyst according to the invention can be used in a non-limiting manner in one or both stages of the hydrocracking process, alone or in combination with another hydrocracking catalyst.

These operating conditions used in the processes according to the invention generally make it possible to achieve conversions per pass, into products having boiling points below 340°C, and better still below 370°C, above 15% by weight and even more preferably between 20 and 100% by weight.

The examples illustrate the invention without limiting its scope.

EXAMPLES

Example 1 - Preparation of Comparative Catalyst A

The catalyst support A is prepared by shaping by kneading-extrusion of 70% weight of USY zeolite having a lattice parameter of 24.37 Å, a SiO2/Al2O3 molar ratio of 11, a specific surface area measured by nitrogen physisorption according to the B.E.T. of 864 m2/g, a micropore volume determined by nitrogen adsorption of 0.29 ml/g and a Bronsted acidity of 339 pmol/g in the presence of commercial boehmite Pural SB3 (Sasol).

The extrudates obtained are dried at 80°C then calcined at 600°C in humid air (5% by weight of water per kg of dry air). The calcined support comprises, on a dry basis, 70% weight of USY zeolite, and 30% weight of alumina. After dry impregnation, the catalyst is dried at 120° C. in air.

Catalyst A is prepared by dry impregnation of the support thus obtained using an aqueous solution containing the elements Ni, Mo. This solution is obtained by dissolving the following precursors in water: nickel nitrate, and heptamolybdate d 'ammonium. The quantity of precursors in solution is adjusted according to the concentrations targeted on the final catalyst.

The mass percentages in catalyst A are respectively: 15.1% by weight of molybdenum (in MoO3 form), 3.3% by weight of nickel (in NiO form) on a dry basis.

Example 2 - Preparation of a catalyst B according to the invention

The support for catalyst B is prepared by shaping by kneading-extrusion of 50% by weight of USY zeolite having a lattice parameter of 24.37 Å, a SiO2/Al2O3 molar ratio of 11, a specific surface area measured by nitrogen physisorption according to the BET method of 864 m2/g, a micropore volume determined by nitrogen adsorption of 0.29 ml/g and a Bronsted acidity of 339 pmol/g, and 20% weight of commercial ZSM-5 zeolite (CBV5020, Zeolyst) having a SiO2/Al2O3 molar ratio of 49.6, a specific surface area measured by nitrogen physisorption according to the BET method of 422 m2/g and a Bronsted acidity of 150 pmol/g, in the presence of commercial boehmite (Pural SB3, Sasol).

The extrudates obtained are dried at 80°C then calcined at 600°C in humid air (5% by weight of water per kg of dry air). The calcined support comprises, on a dry basis, 50% weight of USY zeolite, 20% weight of ZSM-5 zeolite and 30% weight of alumina, i.e. a weight ratio Y/ZSM-5=2.5 in the catalyst. After dry impregnation, the catalyst is dried at 120° C. in air.

Catalyst B is prepared by dry impregnation of the support thus obtained using an aqueous solution containing the elements Ni, Mo. This solution is obtained by dissolving the following precursors in water: nickel nitrate, and heptamolybdate d 'ammonium. The quantity of precursors in solution is adjusted according to the concentrations targeted on the final catalyst.

The mass percentages in catalyst B are respectively: 15.1% by weight of molybdenum (in MoO3 form), 3.3% by weight of nickel (in NiO form) on a dry basis.

Example 3

The performances of the catalysts described above are evaluated in the hydrocracking of a charge comprising a fraction of vacuum distillates and gas oil in one stage using an isothermal test pilot unit in downflow configuration.

This test load undergoes hydrotreating (HDT). After this hydrotreating step, the test batch has a density at 15°C of 0.8755 g/mL, a residual nitrogen content of 23 ppmw and a residual sulfur content of 16 ppmw. The start point of the simulated distillation for this test load after hydrotreating is 163.3°C and the end point is 578.7°C. The 50 wt% point of the simulated distillation is 391.7°C. In order to simulate the partial pressure of hydrogen sulphide and ammonia generated by the HDT stage of the process, the test load is added with DMDS and aniline respectively so as to obtain 8820 ppm wt of sulfur and 1900 ppm wt. weight of nitrogen in the final additivated load.

Each catalyst is evaluated separately and is sulfurized prior to the hydrocracking test under SRGO load or straight run diesel, i.e. diesel from the direct distillation of petroleum containing 4% weight of dimethyl sulphide (DMDS) and 2% weight of aniline. The sulfurization is carried out at WH of 2 h-1 (WH = Hourly Volume Velocity), a H2/charge volume ratio of 1000 NL/L, a total pressure of 140 bar (i.e. 14.0 MPa) and a bearing temperature of 350°C for 6 hours.

After sulfurization, the operating conditions are adjusted to those used for the hydrocracking test: WH of 1.5 h-1, an H2/feed volume ratio of 1000 NL/L, a total pressure of 140 bar (i.e. 14. 0MPa). The temperature of the reactors is set at 380°C in order to evaluate the converting activity of the catalysts after 150 hours under load.

The converting activity is determined from the net conversion and defined as the yield of the cut (or fraction) with a boiling point below 175°C minus the yield of the cut with a boiling point below 175°C present in the test load.

The performances of catalyst B according to the invention are compared with those of catalyst A taken as reference and given in Table 1. The relative activity is obtained by difference in the net conversion between the catalyst according to the invention and that obtained for reference catalyst A. Similarly, the relative yield in light cut below 80°C is taken as the difference between the yields obtained. This light cut includes the gas fraction (C1 -

15 C4) and the light naphtha fraction (C5-80°C). A positive value induces higher activity or performance.

Table 1

Table 1. Characteristics and positioning of the activity and relative yields of catalysts A and B. Catalyst B according to the invention allows both an increase in converting activity with the increase in the conversion of the 175+ cut by 3% compared to the reference catalyst and at the same time an increase in the yield of lower cut at 80°C by 1.2% by weight. Depending on the need, this gain in activity for the conversion to light cut makes it possible both to ensure a higher yield of products of interest for steam cracking without modifying the operating conditions of the process. This advantage can allow operation under less severe operating conditions, thus reducing energy costs for the same level of performance in light cutting.

Claims

27 Claims

1. Hydrocracking catalyst comprising at least one hydro-dehydrogenating element chosen from the group formed by the elements of group VIB and non-noble group VIII taken alone or as a mixture of the periodic table, and a support comprising at least one mineral matrix porous, a zeolite of structural type MFI and a Y zeolite having an initial crystalline parameter aO of the unit cell greater than 24.32 Å and a Bronsted acidity greater than 200 micromole/g.

2. Catalyst according to claim 1, in which the group VIII elements are chosen from iron, cobalt, nickel, taken alone or as a mixture and preferably from nickel and cobalt, the group VIII element content being between 0.5 and 8% by weight of oxide, preferably between 0.5 and 6% by weight of oxide and very preferably between 1.0 and 4% by weight of oxide, relative to the total weight of said catalyst.

3. Catalyst according to one of Claims 1 or 2, in which the elements of group VIB are chosen from tungsten and molybdenum, taken alone or as a mixture, the content of element of group VIB being between 1 and 30% by weight. of oxide, preferably between 2 and 25% by weight of oxide, very preferably between 5 and 20% by weight of oxide, and even more preferably between 5 and 16% by weight of oxide, relative to the total weight of said catalyst.

4. Catalyst according to one of claims 1 to 3 wherein said Y zeolite has a Bronsted acidity of between 250 and 500 micromole/g, preferably between 300 and 500 micromole/g, very preferably between 320 and 500 micromole/g and even more preferably between between 325 and 425 micromole/g.

5. Catalyst according to one of claims 1 to 4 wherein the initial crystalline parameter aO of the unit cell of the zeolite Y is less than 24.55 Å, preferably between 24.32 and 24.50 Å, preferably between 24.32 and 24.45 Å, preferably between 24.32 and 24.40 Å, and very preferably between 24.34 Å and 24.38 Å.

6. Catalyst according to one of claims 1 to 5 wherein said Y zeolite has a micropore volume determined by nitrogen adsorption greater than 0.26 ml/g.

7. Catalyst according to one of claims 1 to 6 wherein said MFI structural code zeolite is a ZSM-5.

8. Catalyst according to claim 7, in which the weight ratio of said Y zeolite to said ZSM-5 zeolite in the catalyst is between 1 and 40.

9. Catalyst according to one of claims 1 to 8 wherein the catalyst has a zeolite Y content of between 7 and 78% by weight relative to the total weight of said catalyst.

10. Catalyst according to one of claims 1 to 9 wherein said catalyst has a content of zeolite with structural code MFI of between 2 and 39% by weight relative to the total weight of said catalyst.

1 1 . Catalyst according to one of Claims 1 to 10, in which the said catalyst has a content of at least one porous mineral matrix of between 4 and 81% by weight relative to the total weight of the said catalyst.

12. Process for the hydrocracking of at least one hydrocarbon feedstock of which at least 50% by weight of the compounds have an initial boiling point above 300°C and a final boiling point below 650°C, at a temperature between between 200°C and 480°C, at a total pressure of between 1 MPa and 25 MPa, with a volume ratio of hydrogen per volume of hydrocarbon charge of between 80 and 5000 liters per liter and at an Hourly Volume Velocity (WH) defined by the ratio of the volume flow rate of hydrocarbon charge to the volume of catalyst charged into the reactor of between 0.1 and 50 h-1, in the presence of the catalyst according to one of Claims 1 to 11.