FR2780307A1 - Bifunctional hydrocracking catalysts based on a dealuminized zeolite and a mixed sulfide phase - Google Patents

Abstract

The incorporation of a sulfide phase imparts a higher acidity and leads to greater activity of the catalyst. Th catalyst comprises a partially dealuminized zeolite Y with a lattice parameter of 2.424 - 2.455 nm and molar SiO2 / Al2O3 global greater than 8, a mineral matrix, a mixed sulfide phase comprising sulfur and elements of groups VB and VIB and optionally a group VIII metal, Si, B or P, and a group VIIA element. An Independent claims is also included for the process for the preparation of the catalyst.

Description

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  The present invention relates to a hydrocracking catalyst for hydrocarbon feedstocks, said catalyst comprising at least one zeolite Y at least partially dealuminated, at least one matrix chosen from the group formed by mineral matrices, preferably of the oxide type, preferably amorphous or poorly crystallized and generally porous, at least one mixed sulphide phase comprising sulfur and at least one element of group VB of the periodic table of the elements (group 5 according to the new notation of the periodic table of the elements, Handbook of Chemistry and Physics, 76th edition, 1995-1996, inside 1st cover page), such as tantalum, niobium and vanadium, preferably niobium as well as at least one element of group VIB of the said classification (group 6), such as chromium , molybdenum or tungsten, preferably molybdenum and tungsten, even more preferably molybdenum. Said catalyst can also optionally comprise at least one metal from group VIII of said classification (groups 8, 9 and 10), such as iron, cobalt, nickel, ruthenium, S5 osmium, rhodium, I ' iridium, palladium, platinum, and possibly at least one element chosen from the group formed by silicon, boron or phosphorus, and possibly at least one element from group VIIA of the said classification (group

  17), such as fluorine, chlorine, bromine, or iodine, preferably fluorine.

  The present invention also relates to the processes for preparing said catalyst, as well as its use for hydrocracking hydrocarbon feedstocks such as petroleum cuts, cuts derived from coal containing aromatic, and / or olefinic, and / or naphthenic compounds, and / or paraffinic, the said fillers optionally containing metals, and / or nitrogen, and / or

oxygen and / or sulfur.

  Hydrocracking of heavy petroleum fractions is a very important refining process which makes it possible to produce, from excess heavy and little recoverable charges, the lighter fractions such as gasolines, jet fuels and light gas oils that the refiner seeks to adapt its production to the structure of demand. Certain hydrocracking processes also make it possible to obtain a highly purified residue which can constitute excellent bases for oils. Compared with catalytic cracking, the advantage of catalytic hydrocracking is to provide middle distillates, jet fuels and diesel oils, of very good quality. The gasoline produced has a much lower octane number than that from

catalytic cracking.

  ? w 2780307 The catalysts used in hydrocracking are all of the bifunctional type combining an acid function with a hydrogenating function. The acid function is provided by supports of large surfaces (150 to 800 m2.g'1 generally) having a surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides , amorphous silica-aluminas and clays. The hydrogenating function is provided either by one or more metals from group VIII of the periodic table of elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a combination of at least one metal of group VI of the periodic table such

  as molybdenum and tungsten and at least one group VIII metal.

  The balance between the two acid and hydrogenating functions is the fundamental parameter which governs the activity and the selectivity of the catalyst. A weak acid function and a strong hydrogenating function give catalysts that are not very active, working at a generally high temperature (greater than or equal to 390 ° C.), and at a low space supply speed (the VVH expressed in volume of charge to be treated per unit catalyst volume and per hour is generally less than or equal to 2) but with very good selectivity for middle distillates. Conversely, a strong acid function and a weak hydrogenating function give active catalysts but having poorer selectivities for middle distillates. The search for a suitable catalyst will therefore focus on a judicious choice of each of the

  functions to adjust the activity / selectivity couple of the catalyst.

  Thus, it is one of the great advantages of hydrocracking to present great flexibility at various levels: flexibility at the level of the catalysts used, which brings flexibility of the feeds to be treated and at the level of the products obtained. A parameter

  easy to control is the acidity of the catalyst support.

  The conventional catalysts for catalytic hydrocracking are, for the most part, made up of weakly acidic supports, such as amorphous silica-aluminas for example. These systems are more particularly used to produce very good quality middle distillates, and again, when their acidity is very low,

oil bases.

  In weakly acidic supports, we find the family of amorphous silica-aluminas.

  Many catalysts in the hydrocracking market are based on silica-alumina

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  associated either with a group VIII metal or, preferably when the heteroatomic content of the charge to be treated exceeds 0.5% by weight, with a combination of sulfides of the metals of groups VIB and VIII. These systems have very good selectivity for middle distillates, and the products formed are of good quality. These catalysts, for the least acidic of them, can also produce lubricating bases. The disadvantage of all these catalytic systems

  amorphous support base is, as has been said, their low activity.

  On the other hand, simple sulfides of elements from group VB have been described as constituents of hydrorefining catalysts for hydrocarbon feedstocks, such as, for example, niobium trisulfide in US Pat. No. 5,294,333. Mixtures of simple sulphides comprising at least one element from group VB and one element from group VIB or group VIII have also been tested as constituents of hydrorefining catalysts for hydrocarbon feedstocks, as for example

  example in patent US-A-4,871,445, patent US-A-4,910,181 or patent US-

A-5.275.994.

  The research carried out by the applicant on zeolites and the hydrogenating active phases, led him to discover that, surprisingly, a hydrocracking catalyst for hydrocarbon feedstocks comprising at least one matrix chosen from the group formed by the matrices mineral, preferably of the oxide type, preferably amorphous or poorly crystallized and generally porous such as alumina, at least one Y zeolite, at least partially dealuminated, and at least one mixed sulfide phase. This catalyst can also optionally contain at least one element from group VIII, optionally an element chosen from the group formed by silicon, phosphorus and boron, optionally at least.

  minus one element chosen from the VIIA group.

  The mixed sulphide phase present in the catalyst according to the invention is characterized by the following approximate general formula Ax B1-x Sy o: x is a number between 0.001 and 0.999, preferably between 0.005 and 0.995, more preferably between 0 , 05 and 0.95,

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  y is a number between 0.1 and 8, and preferably between 0.1 and 6, and even more preferably between 0.5 and 4, A is an element of the group VB, such as tantalum, niobium or vanadium, preferably niobium, B is an element chosen from group VIB, such as chromium, molybdenum or tungsten, preferably molybdenum or tungsten, even more

preferred molybdenum.

  The catalyst according to the invention is in supported form, that is to say that it comprises at least one support constituted by at least one matrix, for example of the oxide type, for example alumina, and at least one zeoltith Y at least partially dealuminated. The catalyst according to the present invention generally contains in% by weight relative to the total mass of the catalyst: - 0.1 to 99.9% preferably 1 to 99.5% and even more preferably 5 to 99.0% d '' at least one matrix, preferably of the oxide type, preferably amorphous or

  poorly crystallized and generally porous.

  - 0.1 to 99.8%, preferably 0.1 to 90% and even more preferably 0.1 to% and very preferably 0.1 to 70% of at least one Y zeolite at least partially dealuminated, whose mesh parameter is between 2,424 nm and 2,455 nm or 24.55A (1A is equal to 10'1 m, or 0.1 nm), preferably between 2,426 nm and 2,438 nm, and whose molar ratio SiO2 / AI203 overall is greater than 8, preferably greater than 10, more preferably greater than 15, and so

very preferred greater than 20.

  -0.1 to 99.5% preferably 0.5 to 99% and even more preferably 1 to 90% of at least one mixed sulphide phase of at least one element of the VB group and of

minus one item from group VIB.

  the catalyst being able to contain in addition - from 0 to 30%, preferably 0 to 25% and even more preferably 0.1 to 20% of at least one metal of group VIII, - from 0 to 20%, preferably 0 to 15%, and more preferably 0.1 to 15% of at least one element chosen from the group formed by boron, phosphorus and silicon, and

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  - from 0 to 15%, preferably 0.1 to 15% and more preferably from 0.1 to 10%

  at least one element chosen from group VIIA, preferably fluorine.

  The matrix is preferably chosen from the group formed by mineral matrices, preferably porous mineral matrices, preferably amorphous or poorly crystallized, and preferably of the oxide type. The identification of the mixed sulfide phase is generally done from the X-ray diffraction diagram. It can also be done from the determination of the metal-metal distance measured by the X-ray absorption technique or "Extended X-ray Absorption Fine Structure "(EXAFS). For example, in the case of a mixed molybdenum and niobium sulfide, the identification by the EXAFS method is done by determining the niobium-niobium or niobium-molybdenum distances if the EXAFS analysis is carried out at the threshold K of niobium. It can also be done by determining the molybdenum-molybdenum and molybdenum-niobium distances if

  EXAFS analysis is carried out at the K threshold of molybdenum.

  The X-ray diffraction diagram is obtained using an INEL diffractometer with curved multidetector using the conventional powder method with the monochromatic radiation K alpha 1 of copper. From the position of the diffraction peaks represented by the angle 2 theta, we calculate, by the Bragg relation, the reticular distances dhkl characteristic of the sample and the lattice parameters of the mixed phase a and c in À ( 1 TO = 1 Angstrom = 10'10m). The lattice parameter "a" represents the average metal-metal distance between two neighboring ions and is characteristic of the existence of a mixed phase. The type of structure can also be determined by diffraction. Thus, for example, in the case of a mixed molybdenum and niobium sulfide, the simple sulfides of Mo and Nb, MoS2 and NbS2, both exist in the form of two types of structure, the hexagonal shape 2s and the shape rhombohedral 3s. For the samples rich in molybdenum (x <0.5) the mixed phase tends to crystallize in the type of hexagonal structure 2s and the mesh parameters vary linearly according to the proportion of niobium in the mixed phase as shown in Table 1 For samples rich in niobium (x ≥ 0.5), the mixed phase tends to crystallize in the rhombohedral structure 3s and the mesh parameters also vary linearly depending on the composition.

  in niobium as shown in Table 2.

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  The estimate of the Delta measurement error (dhkl) over dhkl is calculated, as a function of the absolute error assigned to the measurement of the angle 2 theta, by the Bragg relation. An absolute Delta error (2 theta) equal to +0.05 is commonly accepted. The intensity Irel assigned to each value of dhkl is measured according to the area of the corresponding diffraction peak.

TABLE 1

  Phase a (A) c (A) MoS2-2s 3.16 12.29 Nbo, 2Mo0.8S2 3.20 12.05 Nbo, 3Mo0.5S2 3.22 12.02 Nb0.4Mo0.6S2 3.25 12, 00 NbS2-2s 3.31 11.89

TABLE 2

  Phase a (A) c (A) MoS2-3s 3.16 18.37 Nb0.6Mo0.4S2 3.25 18.00 Nb0.7Mo0.3S2 3.27 17.98 Nb0.8Mo0.2S2 3.30 17, 97 NbS2-3s 3.33 17.81 Analysis of the X-ray diffraction diagram in the form of the mesh parameters presented in Tables 1 and 2 makes it possible to identify the sulfide

mixed niobium and molybdenum.

  Analysis by the EXAFS technique is carried out at the threshold K of niobium using synchrotron radiation between 18850 and 19800 eV by measuring the intensity absorbed by a powder sample deposited on an adhesive strip. The absorption spectrum is analyzed according to an established procedure (FW Lyttle, DE Sayers and EA Stern, Physical Review B, vol 11, page 4825, 1975 and EA Stern, DE Sayers and FW Lyttle, Physical Review B, vol 11, page 4836) which makes it possible to determine the

interatomic distances.

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  Analysis of the X-ray adsorption spectrum makes it possible to deduce a radial distribution function. This radial distribution shows a first peak relating to the sulfur environment of niobium and whose position of the maximum gives the niobium-sulfur distance or R1 in general from 2.45 to 2.48 Å typical of NbS2. We then observe on this radial distribution a second peak corresponding to the second coordination sphere of niobium composed of niobium or molybdenum atoms which cannot be distinguished because of their very close atomic numbers and whose position of the maximum gives the average distance R2 metal-metal (niobium-niobium or niobium-molybdenum), the value of which varies according to the composition of the mixed phase as shown in Table 3; said value lies between the values of the niobium-niobium distance in NbS2 (3.33 A) and the molybdenum-molybdenum distance in MoS2 (3.16 A), and it is generally on average from 3.20 to 3.35 AT. This distance is in agreement with the distances a determined by X-ray diffraction and varies with the composition of the mixed phase. The distances reported in Table 3 are corrected for phase shift and can therefore be compared with data obtained by X-ray diffraction. The determination of metal-to-metal interatomic distances by the EXAFS technique is very precise since the estimation of the absolute error over the distance is equal to + 0.02 A.

TABLE 3

  Phase R1 (A) R2 (A) Nbo, 2Mo0.8S2 2.46 3.20 Nbo, 3Mo0.7S2 2.45 3.22 Nbo, 4Mo0.6S2 2.48 3.27 Nbo, 6Mo0.4S2 2.47 3.28 Nbo, 7Moo0.3S2 2.47 3.30 Nbo, 8Moo, 2S2 2.48 3.31 NbS2 2.48 3.33 The catalyst according to the invention can be prepared either by first preparing a phase mixed mass sulfide and then depositing it on a support, either by directly generating a catalyst precursor consisting of a supported mixed sulfide phase. The optional elements which may be present (elements from group VIII, elements chosen from the group formed by silicon, phosphorus and

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  boron, elements of group VIIA) can be introduced at any stage of the preparation, for example during the preparation of the mass mixed sulphide phase

  or supported, or on the support alone.

  A preferred process for preparing the mass mixed sulphide phase included in the catalyst according to the present invention comprises the following steps: a) a reaction mixture is formed which contains at least the following compounds at least one source of element of group VB, at least one source of element from group VIB, possibly water, possibly at least one source of an element chosen from the group formed by elements from group VIII, possibly at least one source from an element chosen from group formed by silicon, the

  phosphorus and boron, optionally an element chosen from halogens, that is to say

  say the elements of group VIIA, preferably fluorine, i5 b) said mixture is maintained at a heating temperature generally greater than about 40 C, at a pressure at least equal to atmospheric pressure and in the presence of a sulfur compound until we get

said mixed sulfide phase.

  The mixing carried out in step a) above can be carried out simultaneously or successively, the order little important, in the same physical space or separately. Step b) turns out to be very difficult by most conventional methods of

  sulfurization known to those skilled in the art.

  In fact, the sulfurization of solids containing at least one element of the VB group in oxide form proves to be very difficult by most of the conventional sulfurization methods known to those skilled in the art. Catalysts containing at least one element of group VB supported on an alumina-type matrix are known

  to be very difficult to sulfurize, once the element association of the group VB-

  matrix has been calcined at a temperature above 200 C.

  A preferred method according to the invention consists in not calcining the catalyst and in carrying out the sulfurization with a gaseous compound comprising sulfur such as CS2

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  pressure autoclave. Thus, a preferred method according to the invention consists in carrying out the sulfurization of the mixture, generally in the form of powdered solids, at a temperature between 40 and 700 C, preferably between 60 and 500 C, under autogenous pressure and in the presence of a gaseous sulfur compound such as preferably CS2. It is preferable to use an autoclave internally coated with a polymer material, generally polytetrafluoroethylene, at a temperature above 100 C. The duration of the heating of the reaction mixture necessary for sulfurization depends on the composition of the reaction mixture and on the temperature of reaction. Such a method, described in the literature for the synthesis of a catalyst comprising niobium sulphide on alumina (Journal of Catalysis, vol. 156, pages 279-289 (1995)) and in patent EP-A-440,516 for the synthesis of a binary sulfur compound, i.e. a simple sulfide comprising sulfur and another element, transition metal or rare earth, has been found applicable for the synthesis of mixed sulfides

according to the present invention.

  The supported catalysts of the present invention can be prepared by any method known to those skilled in the art. Some of the methods of

  Possible preparations are described below.

  In general, it is possible to mechanically mix the dealuminated Y zeolite and the matrix generally in powder form with any precursor of the phase.

  mixed sulfide, then proceed with sulfiding, as described in more detail below

  after. It is also possible to produce a mechanical mixture comprising on the one hand a powder of mixed sulfide, synthesized according to one of the methods described above, and on the other hand of the support (that is to say a mixture of matrix and zeolite) also in powder form, then optionally

formatting.

  In all cases it is a priori possible to add any elements present on the supported catalyst according to the invention at any stage of the preparation, according to the

  methods known to those skilled in the art.

/ OsU

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  One of the preferred processes for preparing the supported mixed sulfide phase included in the catalyst according to the invention comprises the following steps: a) a reaction mixture is formed which contains at least the following compounds at least one matrix chosen from the group formed by the mineral matrices, preferably of the oxide type, preferably amorphous or poorly crystallized and generally porous, at least one zeolite Y, at least partially dealuminated, whose lattice parameter is between 2,424 nm and 2,455 nm, preferably between 2,426 nm and 2.438 nm, and whose overall SiO2 / AI203 molar ratio is greater than 8, preferably greater than 10, more preferably greater than 15, and very preferably greater than 20, at least one element source of the group VB , at least one source of element from group VIB, possibly water, possibly at least one element chosen from the group formed by the elements nts of group VIII, optionally at least one source of an element chosen from the group formed by silicon, phosphorus and boron,

  optionally at least one source of an element chosen from halogens, that is

  that is to say the elements of group VIIA, preferably fluorine, b) said mixture is maintained at a heating temperature generally above about 40 ° C. in the presence of a sulfur compound until a solid is obtained containing at least one matrix, at least one Y zeolite

  dealuminated and at least one mixed sulfide phase.

  Preferably step a) is a step of impregnating the support.

  Thus, for example in the preferred case where the metal of group VB is niobium and where the metal of group VIB is molybdenum, it is possible to impregnate the support (comprising the matrix and the zeolite) or the matrix alone, by example of alumina, with ammonium heptamolybdate, to carry out a drying at 80 ° C., then to impregnate with niobium oxalate, to carry out a drying at 80 ° C., and to carry out a sulfurization for example and preferably by CS2 in autoclave under autogenous pressure, as described for the preparation of the sulphide phase

  mixed mass, for example at 400 C for 10 hours.

  It is also possible to produce the mixture of powders comprising the source of element of group VB, the source of element of group VIB, optionally of

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  water, possibly the source of the element chosen from silicon, phosphorus and boron, possibly the source of the element from group VIIA and possibly the source of sulfur and permeate the support. It is also possible to impregnate the matrix alone and to add the Y zeolite thereafter, by any means known to those skilled in the art, for example by mechanical mixing. When the matrix is impregnated, the impregnation of the matrix is preferably carried out by the so-called "dry" impregnation method well known to those skilled in the art. Impregnation can be carried out in one step with a solution

  containing all the constituent elements of the final catalyst.

  The shaping of the support or of the supported catalyst according to the invention may be an extrusion, a pelletizing, the oil drop method, a granulation on a turntable or any other well-known method of skilled in the art. The preformed support is optionally calcined in air, usually at a

  temperature of at least 300 C, usually around 350 to 1000 C.

  The mixed sulphide phase, as well as the element from group VIII, as well as the element chosen from the group formed by P, B and Si and the element chosen from group VIIA, halides, preferably fluorine, may be introduced in the

  catalyst at various levels of preparation and in various ways.

  The mixed sulphide phase can be introduced only in part (case for example of the association of at least one metal from group VB and / or from group VIB and from at least one metal from group VIII) or in whole at the time of kneading of the matrix

  porous, possibly with all or part of the zeolite.

  The metal of group VIII as well as the element chosen from the group formed by P, B, Si and the element chosen from halides from group VIIA, can be introduced by one or more ion exchange operations on the calcined matrix consisting of mixed sulfide dispersed in the chosen support, using a solution containing at least one group VIII metal precursor salt. It can be introduced by at least one operation of impregnating the shaped and calcined support, with a precursor solution of at least one group VIII metal (in particular cobalt and / or

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  nickel), any group VIII metal precursor preferably being introduced as

  same time or after any metal precursor of the VB and VIB group.

  In the case where the metals are introduced in several impregnations, corresponding precursor salts, an intermediate drying step of the catalyst is generally carried out at a temperature generally between 60 and C. The porous mineral matrix, usually amorphous or poorly crystallized, is in general consisting of at least one refractory oxide in amorphous or poorly crystallized form. Said matrix is usually chosen from the group formed by alumina, silica, silica-alumina, or a mixture of at least two of the oxides mentioned above. We can also choose aluminates. It is preferred to use matrices containing alumina, in all these forms known to those skilled in the art.

  loom, for example gamma alumina.

  Among the Y zeolites, it is usually preferred to use Y zeolites whose ratio expressed in atom of framework silicon / aluminum (Si / AI) is greater than approximately 3: 1. Advantageously, zeolites with a faujasite structure are used, and in particular stabilized and ultra-stabilized YY zeolites YY, either in hydrogen form or in partially exchanged form with metal cations, for example cations of alkali or alkaline earth metals and / or cations of rare earth metals with atomic number 57 to 71 inclusive (Molecular Zeolite

  Sieves Structure, Chemistry and Uses, D.W. BRECK, J. WILLEY and Sons, 1973).

  The dealuminated Y zeolite is characterized by a mesh parameter (crystalline parameter) of between 2,424 nm and 2,455 nm, preferably between 2,426 nm and 2,438 nm, and whose overall SiO2 / AI203 molar ratio is greater than 8, preferably greater than 10, more preferably greater than 15, and very preferably

greater than 20.

  Preferably, a dealuminated Y zeolite is used which also has the following properties: a SiO2 / Al2O3 molar ratio of framework greater than or equal to the molar ratio

SiO2 / AI203 global.

  a content of cations of alkaline earth or alkali metals and / or cations of rare earths (of atomic number 57 to 71 inclusive) such as the atomic ratio

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  [nx Mn + l / AI (n being the charge of the cation M) is less than 0.8, preferably less than 0.5, and even more preferably less than 0.1, - a specific surface area determined by the BET method greater than approximately 400 m2 / g, and preferably greater than 550 m2 / g - a water adsorption capacity at 25 C for a P / Po value of 0.2, greater than

about 6% by weight.

  The sources of element of the VB group which can be used are well known to those skilled in the art. For example, among the sources of niobium, oxides can be used, such as diniobium pentaoxide Nb2Os, niobic acid Nb2Os5.H20, niobium hydroxides and polyoxoniobates, niobium alkoxides of formula Nb (OR1) 3 o R1 is an alkyl radical, niobium oxalate NbO (HC204) 5, ammonium niobate. Preferably niobium oxalate or ammonium niobate is used. The sources of elements of group VIB which can be used are well known to those skilled in the art. For example, among the sources of molybdenum and tungsten, it is possible to use oxides and hydroxides, molybdic and tungstic acids and their salts, in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, ammonium tungstate, phosphomolybdic acid, phosphotungstic acid and their salts, silicomolybdic acid, silicotungstic acid and their salts. Oxides and ammonium salts such as ammonium molybdate, heptamolybdate are preferably used

  ammonium and ammonium tungstate.

  The sulfur source can be elemental sulfur, carbon sulfide, hydrogen sulfide, sulfur hydrocarbons such as dimethyl sulfide, dimethyl disulfide, mercaptans, thiophene compounds, thiols, polysulfides such as for example ditertiononylpolysulfide or TPS-37 from the company ATOCHEM, petroleum cuts rich in sulfur such as petrol, kerosene, diesel, alone or in mixtures with one of the sulfur compounds cited above. The

  preferred sulfur source is carbon sulfide or hydrogen sulfide.

  The preferred phosphorus source is phosphoric acid H3PO4, but its salts and esters such as alkaline phosphates, ammonium phosphates, gallium phosphates or alkyl phosphates are also suitable. Phosphorus can by

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  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 the family of

  pyridine and quinolines and compounds of the pyrrole family.

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

  silicone type suspended in water.

  The boron source 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 means of a solution

  boric acid in a water / alcohol mixture.

  The sources of elements of the VIIA group which can be used are well known to those skilled in the art. For example, the fluoride anions can be introduced in the form of 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 hydrolysable compounds which can release fluoride anions in water, such as ammonium fluorosilicate (NH4) 2SiF6, silicon tetrafluoride SiF4 or sodium Na2SiF6. Fluorine can be introduced for example by impregnation of a solution

  aqueous hydrofluoric acid or ammonium fluoride.

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  The catalyst of the present invention may contain a group VIII element such as

  as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum.

  Among the metals of group VIII, it is preferred to use a metal chosen from the group formed by iron, cobalt, nickel and ruthenium. Advantageously, the following combinations of metals are used: nickel-niobium-molybdenum, cobalt-

  niobium-molybdenum, iron-niobium-molybdenum, nickel-niobium-tungsten, cobalt-

  niobium-tungsten, iron-niobium-tungsten, the preferred associations being: nickel-

  niobium-molybdenum, cobalt-niobium-molybdenum. It is also possible to use

  combinations of four metals, for example nickel-cobalt-niobiummolybdenum.

  It is also possible to use combinations containing a noble metal such as

  ruthenium-niobium-molybdenum, or alternatively ruthenium-nickel-niobiummolybdenum.

  The impregnation of molybdenum can be facilitated by adding phosphoric acid to the ammonium paramolybdate solutions, which also makes it possible to introduce phosphorus so as to promote catalytic activity. Other compounds of

  phosphorus can be used as is well known to those skilled in the art.

  The catalysts obtained by the present invention are shaped, in the form of grains of different shape and dimensions. They are generally used in the form of cylindrical or multi-lobed extrudates such as two-lobed, three-lobed, multi-lobed in straight or twisted shape, but can optionally be manufactured and used in the form of crushed powder, tablets, rings, balls , wheels. They have a specific surface area measured by nitrogen adsorption according to the BET method (Brunauer, Emmett, Teller, J. Am. Chem. Soc., Vol. 60, 309-316 (1938)) of between approximately 50 and approximately 600 m2 / g, a pore volume measured by mercury porosimetry of between approximately 0.2 and approximately 1.5 cm 3 / g and a size distribution of

  pores can be monomodal, bimodal or polymodal.

  The catalysts obtained by the present invention are used for hydrocracking hydrocarbon feedstocks such as petroleum fractions. The fillers used in the process are gasolines, kerosene, gas oils, vacuum gas oils, atmospheric residues, vacuum residues, atmospheric distillates, vacuum distillates, heavy fuels, oils, waxes and paraffins, used oils, deasphalted residues or crudes, fillers from thermal or catalytic conversion processes and their

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  mixtures. They contain heteroatoms such as sulfur, oxygen and nitrogen and

possibly metals.

  The catalysts thus obtained are advantageously used for hydrocracking in particular heavy hydrocarbon cuts of the vacuum distillate type, deasphalted or hydrotreated residues or the like. Heavy cuts are preferably made up of at least 80% by volume of compounds whose boiling points are at least 350 C and preferably between 350 and 580 C (i.e.

  corresponding to compounds containing at least 15 to 20 carbon atoms).

  They generally contain heteroatoms such as sulfur and nitrogen. The nitrogen content is usually between 1 and 5000 ppm by weight and the sulfur content

between 0.01 and 5% by weight.

  The hydrocracking conditions such as temperature, pressure, hydrogen recycling rate, hourly volume speed, may be very variable depending on the nature of the feed, the quality of the desired products and the facilities available to the refiner. The temperature is generally greater than C and preferably between 250 C and 480 C. The pressure is greater than 0.1 MPa and preferably greater than 1 MPa. The quantity of hydrogen is at least 50 and often between 80 and 5000 normal liters of hydrogen per liter of charge. The hourly space velocity is included in

  generally between 0.1 and 20 volume of feed per volume of catalyst and per hour.

  The catalysts of the present invention are optionally subjected to a complementary sulfurization treatment before being used in the hydrocracking reaction. This treatment makes it possible to transform, at least in part, the residual metallic species into sulphide before they are brought into contact with the charge to be treated. This sulfurization activation treatment is well known to those skilled in the art.

  profession and can be carried out by any method already described in the literature either

  situ, that is to say in the hydrocracking reactor, or ex-situ.

  A conventional sulfurization method well known to those skilled in the art consists of heating in the presence of hydrogen sulphide at a temperature between 150 and 800 ° C., preferably between 250 and 600 ° C., generally in a reaction zone

with crossed bed.

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  The catalyst of the present invention can advantageously be used for the hydrocracking of sections of the distillate type under vacuum highly charged with sulfur and nitrogen, more particularly for example, sections with a sulfur content greater than

  0.1% by weight and with a nitrogen content greater than 10 ppm.

  In a first embodiment or partial hydrocracking also called mild hydrocracking, the conversion level is less than 55%. The catalyst according to the invention is then used at a temperature generally greater than or equal to 230 C, preferably between 300 C and 480 C, and more preferably between 350 C and 450 C. The pressure preferably greater than 2 MPa , more preferably 3MPa, and preferably less than 12MPa, more preferably less than 10MPa. The amount of hydrogen is at least 100 normal liters of hydrogen per liter of charge, and preferably between and 3000 normal liters of hydrogen per liter of charge. The hourly volume speed is preferably between 0, 15 and 10 volume of feed per volume of catalyst and per hour. Under these conditions, the catalysts of the present invention exhibit better activity in conversion, in hydrodesulfurization and in

  hydrodenitrogenation than commercial catalysts.

  In a second embodiment, the catalyst of the present invention can be used for partial hydrocracking, advantageously under conditions of moderate hydrogen pressure, of sections, for example of the vacuum distillate type highly charged with sulfur and nitrogen which have been previously hydrotreated. In this hydrocracking mode the conversion level is less than 55%. In this case, the petroleum cut conversion process takes place in two stages, the catalysts according to the invention being used in the second stage. The catalyst of the first stage has a hydrotreatment function and comprises a matrix preferably based on alumina, and preferably not containing a zeolite, and at least one metal having a hydrogenating function. Said matrix is an porous amorphous or poorly crystallized oxide-type mineral matrix. Mention may be made, by way of nonlimiting example, of aluminas, silicas, silica-aluminas. We can also choose aluminates. It is preferred to use matrices containing alumina, in all these forms known to a person skilled in the art, and even more preferably aluminas, for example gamma alumina. The hydrotreatment function is provided by at least one metal or group VIII metal compound such as nickel and cobalt in particular. You can use a combination of at least one metal

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  or a compound of group VIB metal (for example molybdenum or tungsten) and at least one metal or a group VIII metal compound (for example cobalt or nickel) of the periodic table. The total concentration of metal oxides of groups VIB and VIII is preferably between 5 and 40% by weight and more preferably between 7 and 30% by weight and the weight ratio expressed as metal oxide (of metals) of group VIB on metal oxide (of metals) of group VIII is preferably between 1.25 and 20, and more preferably between 2 and 10. In addition, this catalyst may contain phosphorus. The phosphorus content, expressed as a concentration of diphosphorus pentoxide P205, will preferably be at most 15%, more preferably between 0.1 and 15% by weight and very preferably between 0, 15 and 10% by weight. weight. It can also contain boron in a B / P ratio preferably between 1.05 and 2 (atomic), the sum of the contents of boron (B) and phosphorus

  (P) expressed as oxides being preferably between 5 and 15% by weight.

  The first step generally takes place at a temperature between 350 and 460 C, preferably between 360 and 450 C, a total pressure of at least 2 MPa, preferably at least 3 MPa, an hourly volume speed of between 0.1 and 5 volume of charge per volume of catalyst and per hour, preferably between 0.2 and 2 volume of charge per volume of catalyst and per hour and with a quantity of hydrogen of at least 100 normal liters per liter of charge, and preferably

  between 260 and 3000 normal liters per liter of charge.

  For the conversion step with the catalyst according to the invention (or second step), the temperatures are generally greater than or equal to 230 C and often between 300 C and 480 C and preferably between 300 and 4500C. The pressure is generally at least 2MPa and preferably at least 3MPa. The quantity of hydrogen is at least 100 liters of hydrogen per liter of charge and

  preferably between 200 and 3000 liters of hydrogen per liter of charge.

  The hourly volume speed is preferably between 0.15 and 10 volume of feed per volume of catalyst and per hour. Under these conditions, the catalysts of the present invention exhibit better activity in conversion, hydrodesulfurization, hydrodenitrogenation and better selectivity in middle distillates than commercial catalysts. The service life of the catalysts is

  also improved in the moderate pressure range.

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  In another embodiment, the catalyst of the present invention can be used for hydrocracking under high hydrogen pressure conditions, generally at least 5 MPa. The treated sections are, for example, of the vacuum distillates type highly charged with sulfur and nitrogen which have been hydrotreated beforehand. In this hydrocracking mode the conversion level is greater than%. In this case, the oil cut conversion process takes place in two

  stages, the catalyst according to the invention being used in the second stage.

  The catalyst of the first stage has a hydrotreatment function and comprises a matrix preferably based on alumina, and preferably not containing a zeolite, and at least one metal having a hydrogenating function. Said matrix can also consist of, or contain, silica, silica-alumina, boron oxide, magnesia, zirconia, titanium oxide or a combination of these oxides. The hydro-dehydrogenating function is provided by at least one metal or compound of group VIII metal such as nickel and cobalt in particular. It is possible to use a combination of at least one metal or compound of group VIB metal (for example molybdenum or tungsten) and of at least one metal or compound of group VIII metal (for example cobalt or nickel) of the Periodic Table of the Elements. The total concentration of metal oxides of groups VIB and VIII is preferably between 5 and 40% by weight and more preferably between 7 and 30% by weight and the weight ratio expressed as metal oxide to metal (or metals) of the group VIB on group VIII metal (or metals) is preferably between 1.25 and 20 and more preferably between 2 and 10. In addition, this catalyst may optionally contain phosphorus. The phosphorus content, expressed as a concentration of diphosphorus pentoxide P205, will preferably be at most 15%, more preferably between 0.1 and 15% by weight and very preferably between 0.15 and 10% by weight. . It can also contain boron in a B / P ratio preferably between 1.02 and 2 (atomic), the sum of the contents of boron (B) and phosphorus (P) expressed in oxides being preferably between and 15% by weight . The first step generally takes place at a temperature between 350 and 460 C, preferably between 360 and 450 C, a pressure of at least 2MPa, preferably at least 3MPa, an hourly volume speed between 0.1 and 5 volume of feed per volume of catalyst per hour, preferably between 0.2 and 2 volume of feed per volume of catalyst per hour and with an amount

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  of hydrogen of at least 100 normal liters of hydrogen per liter of charge, and preferably between 260 and 3000 normal liters of hydrogen per liter of charge. For the conversion step with the catalyst according to the invention (or second step), the temperatures are generally greater than or equal to 230 C, often between 300 C and 480 C, and preferably between 330 C and 440 C The pressure is generally greater than 5MPa and preferably greater than 7MPa. The quantity of hydrogen is at least 100 liters of hydrogen per liter of charge and

  preferably between 200 and 3000 liters of hydrogen per liter of charge.

  The hourly volume speed is preferably between 0.15 and 10 volume

  load per volume of catalyst and per hour.

  Under these conditions, the catalysts of the present invention exhibit a

  better conversion activity than commercial catalysts.

  The following examples illustrate the present invention without, however, limiting its scope. Example 1: Preparation of a support containing a Y zeolite (in accordance with the invention) A hydrocracking catalyst support containing a Y zeolite was produced in large quantities so as to be able to prepare different catalysts based on the same support. For this, 20.5% by weight of a dealuminated Y zeolite with a crystalline parameter equal to 2.429 nm and an overall SiO2 / AI203 ratio of 30.4 and

  structural SiO2 / AI203 ratio of 58 [calculated according to the so-called Fichtner correlation-

  Schmittler (in Cryst. Res. Tech. 1984, 19, K1)] which is mixed with 79.5% by weight of a matrix composed of ultrafine tabular boehmite or alumina gel sold under the name SB3 by the company Condéa Chemie Gmbh. This powder mixture was then mixed with an aqueous solution containing 66% nitric acid (7% weight of acid per gram of dry gel) and then kneaded for minutes. At the end of this kneading, the dough obtained is passed through a die having cylindrical orifices with a diameter equal to 1.4 mm. The extrudates are then dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours under humid air containing 7.5% volume of water. This produces cylindrical extrudates of 1.2 mm in diameter, with a specific surface of 223 m2g and a

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  monomodal pore size distribution centered on 10 nm. Analysis of the matrix by X-ray diffraction reveals that it is composed of gamma alumina

  cubic with low crystallinity and dealuminated Y zeolite.

  Example 2 Preparation of a hydrocracking catalyst containing a Y zeolite and a mixed sulphide phase (in accordance with the invention) The support extrudates containing a dealuminated Y zeolite from Example 1 are dry impregnated with an aqueous solution of '' a mixture of ammonium heptamolybdate and nickel nitrate, dried overnight at 120 C in air. The oxide contents by weight of the catalyst A obtained are shown in Table 1, it contains in particular 17.1% by weight of zeolite Y with a mesh parameter of 2.429 nm

  overall SiO2 / AI203 ratio of 30.4 and structural SiO2 / AI203 ratio of 58.

  Catalyst A is impregnated with an aqueous solution of niobium oxalate Nb (HC204) 5, oxalic acid and ammonium oxalate. The aqueous solution containing niobium is prepared from 1330 ml of water in which it is dissolved

  33g of oxalic acid, 37.2g of ammonium oxalate and 92.3g of niobium oxalate.

  To prepare the solution, the oxalic acid and ammonium oxalate mixture is first dissolved and when the solution is clear, said solution is heated to 55 ° C. and the niobium oxalate is added. It is then made up with water to obtain 1330 ml of solution. The support of example 1 above is impregnated by the so-called excess solution method. The 1330 ml of solution are brought into contact with 380 g of catalyst. This makes it possible to deposit approximately 5% by weight of Nb on the catalyst. After two hours, the extrudates are recovered. These are then dried overnight at 120 ° C. under a stream of dry air. Catalyst B obtained contains

  in particular 16.3% by weight of zeolite Y with a mesh parameter of 2.429 nm.

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  Table 1: Characteristics of the catalysts (after calcination for 2 hours at 500 ° C. in dry air) ABCDEF catalyst Nb2O5 (% wt) 0 4.8 4.8 4.9 4.9 4.8 4.8 MoO3 (% wt) 13.5 11 .8 11.8 11.6 11.3 11.2 NiO (% wt) 3.1 2.9 2.8 2.9 2.85 2.8 B203 (% wt) o 0 0 0 1.9 1 .9 SiO2 (% wt) 16.0 15.2 15.3 16.8 16.5 16.4 F (% wt) 0 0 0 0 0 0.99 Y (% wt) 17.1 16.3 16 , 3 15.6 15, 7 15.5 Complement at 100% j6, Complement at 100% amn67.4 65.3 65.3 63.8 62.7 61.9 composed mainly of A1203 (% wt) Catalysts A and B prepared above were sulfurized in an autoclave under autogenous pressure in the presence of CS2. For 100 g of catalyst, 20 ml of CS2 are added to the autoclave, closed and heated at 400 ° C. for 10 hours. The

  internal pressure is then about 4 MPa. This sulphurization is called Sl.

  Other aliquots of catalysts A and B prepared above were sulfurized in a fixed-bed catalyst reactor swept by a stream of gas containing 15% H 2 S in nitrogen at atmospheric pressure. For 5 g of catalyst, 2 liters per hour of the mixture are passed through and the catalyst is heated to a temperature of 600 ° C.

  for 6 hours. This sulfurization is called S2.

  Analysis is then carried out by the EXAFS technique at the threshold K of niobium using synchrotron radiation between 18850 and 19800 eV by measuring the intensity absorbed by a powder sample deposited on an adhesive strip. It makes it possible to determine the interatomic distances. The distances R2 measured (in angstrom, 1A = 10 'm by EXAFS for the samples of catalysts A and B sulfurized respectively by the method S1 and by the method S2 are reported in

table 2.

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Table 2

  Catalyst Catalyst sulfurized by R2 (A) sulfurized by R2 (A) Sl method S2 method

B-S1 1 3.21 B-S2 3.21

_ C-S1 3.33 C-S2 3.33

D-S1 3.20 D-S2 3.21

E-S1 3.21 E-S2 3.21

F-S1 3.20 F-S2 3.20

  Example 3: Preparation of hydrocracking catalysts containing a Y zeolite and an element of the VB group (not in accordance with the invention) A hydrocracking catalyst containing a Y zeolite and niobium was produced. This preparation is carried out by co-mixing a mixture of ultrafine tabular boehmite or alumina gel marketed under the name SB3 by the company Condéa Chemie Gmbh, of a dealuminated Y zeolite with a crystalline parameter equal to 2.429 nm and an overall SiO2 / AI203 ratio of 30.4 and SiO2 / AI203 framework ratio of 58 [calculated from the so-called Fichtner-Schmittler correlation (in Cryst. Res. Tech. 1984, 19, K1)], nickel nitrate, niobium pentoxide and ammonium heptamolybdate. To form the paste, these sources are used so as to obtain a catalyst containing 16.5% by weight of zeolite Y, 63% by weight of alumina, 13% by weight of molybdenum oxide, 3% by weight of nickel oxide, and 5% by weight of niobium oxide. At the end of this kneading, the dough obtained is passed through a die having cylindrical orifices with a diameter equal to 1.4 mm. The extrudates are then dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours under humid air containing 7.5% volume of water. Catalyst C is obtained in the form of cylindrical extrudates of 1.2 mm in diameter, the

  contents are indicated in table 1.

  The catalyst C prepared above is then sulfurized according to the S1 method of Example 2 in an autoclave under autogenous pressure in the presence of CS2. Another aliquot of catalyst C prepared above is sulfurized according to method S2 of

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  Example 2 in a fixed bed catalyst reactor swept by a gas stream containing 15% H2S in nitrogen at atmospheric pressure. We then proceed to the analysis of these sulfur catalysts by the EXAFS technique as indicated in

  Example 1. The distances R2 measured by EXAFS for the samples CS1 and C-

  S2 sulfurized by the S1 method and the S2 method respectively are reported

in table 2.

  Whatever the sulfurization method, it is clearly seen in Table 2 that the catalysts containing both niobium and molybdenum prepared according to the invention have a metal-metal distance R2 of the sulfide phase less than that of catalyst C. The R2 value of 3.33 A for catalyst C indicates that in this catalyst the niobium is in the form of an NbS2 phase identical to that of a catalyst which would contain only niobium alone. The metal-metal distance R2 of 3.20 A intermediate between the value of NbS2 and MoS2, indicates the presence of a mixed sulphide phase of niobium and molybdenum in catalyst B. Example 4: Preparation of hvdrocraquaae catalysts containing a zeolite Y and a mixed sulfide phase (according to the invention) Catalyst A was then impregnated with an aqueous solution containing an emulsion of Rhodorsil EP1 silicone (Rhone-Poulenc). After maturation at room temperature in an atmosphere saturated with water, the impregnated extrudates

  are then dried overnight at 120 C. Catalyst A1 is obtained.

  We impregnated the sample of catalyst A with an aqueous solution

  containing ammonium biborate and Rhodorsil EPI silicone emulsion (Rhone-

  Poulenc). After maturing at room temperature in a water-saturated atmosphere, the impregnated extrudates are dried overnight at 120 C.

thus catalyst A2.

  The catalysts A1 and A2 are then impregnated with an aqueous solution of niobium oxalate Nb (HC204) 5, oxalic acid and ammonium oxalate. The aqueous solution containing niobium is prepared from 1330 ml of water in which 33 g of oxalic acid, 37.2 g of ammonium oxalate and 92.3 g of oxalate are dissolved.

niobium.

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  To prepare the solution, the oxalic acid and ammonium oxalate mixture is first dissolved and when the solution is clear, said solution is heated to 55 ° C. and the niobium oxalate is added. It is then made up with water to obtain 1330 ml of solution. Catalysts A1 and A2 are impregnated by the so-called excess solution method. The 1330 ml of solution are brought into contact with 380 g of catalyst. This makes it possible to deposit approximately 5% by weight of Nb on the catalyst. After two hours, the extrudates are recovered. These are then dried overnight at 120 ° C. under a stream of dry air. Catalyst D is obtained from catalyst A1, it contains in particular Nb and silicon. Catalyst E is obtained from

  catalyst A2, it contains in particular Nb, silicon and boron.

  Fluorine is then added to catalyst E, by impregnation of a dilute hydrofluoric acid solution so as to deposit approximately 1% by weight of fluorine. After drying overnight at 120 ° C. in dry air, catalyst F is obtained. The characteristics of catalysts D, E and F are summarized in Table 1. The catalysts D, E and F prepared above are then sulfurized according to the Sl method of Example 2 in an autoclave under autogenous pressure in the presence of CS2. Catalysts D, E and F prepared above are also sulfurized according to method S2 of Example 2 in a fixed bed reactor of catalyst swept by a stream of

* gas containing 15% H2S in nitrogen at atmospheric pressure.

  Analysis is then carried out by the EXAFS technique of these catalysts according to the method indicated in Example 1. The distances R2 measured by EXAFS for the samples D, E and F sulfurized respectively by the method Sl and by the method S2 are reported in Table 2. The distance R2 of 3.20 Å and 3.21 Å measured for catalysts D, E and F indicates the existence of a mixed sulfide phase

niobium and molybdenum.

  EXAMPLE 5 Comparison of the Hydrocracking Catalysts of a Vacuum Gqazole at

partial conversion.

  The catalysts, the preparations of which are described in the preceding examples, are used under the conditions of hydrocracking at moderate pressure on an oil charge, the main characteristics of which are as follows:

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  Density (20/4) 0.921 Sulfur (% by weight) 2.46 Nitrogen (ppm by weight) 1130 Simulated distillation initial point 365 C point 10% 430 C point 50% 472 C point 90% 504 C end point 539 C pour point + 39 C. The catalytic test unit comprises two reactors in a fixed bed, with upward flow of the charge ("up-flow". In the first reactor, the one in which the charge passes first, the first stage catalyst is introduced hydrotreatment HTH548 sold by the company Procatalyse comprising an element of group Vl and an element of group VIII deposited on alumina. In the second reactor, the one in which the charge passes last, a hydrocracking catalyst described above is introduced 40 ml of catalyst are introduced into each of the reactors The two reactors operate at the same temperature and at the same pressure The operating conditions of the test unit are as follows: Total pressure 5 MPa Hydrotreatment catalyst 40 cm3 Hydrocracking catalyst 40 cm3 Temperature 400 C Hydrogen flow 20 I / h Charging flow 40 cm3 / h

  The two catalysts undergo an in-situ sulfurization step before reaction.

  Note that any in-situ or ex-situ sulfurization method is suitable. Once

  the sulfurization carried out, the charge described above can be transformed.

  The catalytic performances are expressed by the gross conversion at 400 C (CB), by the gross selectivity in middle distillates (SB) and by the conversions in hydrodesulfurization (HDS) and in hydrodenitrogenation (HDN). These catalytic performances are measured on the catalyst after a stabilization period, generally at least 48 hours, has been observed. The gross conversion CB is taken equal to: CB =% wk of 380m ns of the effluent The fraction 380 minus the effluent signifying the part of the effluent boiling at

below 380 C.

  The gross selectivity SB in middle distillates is taken equal to: SB = 100 * weight of the fraction (150 C-380 C) / weight of the fraction 380mo ins of the effluent The conversion to hydrodesulfurization HDS is taken equal to: HDS = (Sinitial - Seffluent) / Sinitial * 100 = (24600 - Seffluent) / 24600 * 100 The conversion to HDN hydrodenitrogenation is taken equal to: HDN = (Ninitial - Neffluent) / Ninitial * 100 = (1130 - Neffluent) / 1130 * 100 In the following table 3, we have reported the raw conversion CB to 400 C, the gross selectivity SB, the conversion to hydrodesulfurization HDS and the conversion to

  HDN hydrodenitrogenation for the four catalysts.

  Table 3: Catalytic activities of catalysts in partial hydrocracking at 400 C

CB SB HDS HDN

  o (% wt) (%) (%) (%) A NiMo / Y 47, 1 76.0 97.0 94.2 B NiMoNb / Y 47, 3 79.4 98.1 95.6 C NiMoNb / Y (comparative) 47.8 75.8 97.9 95.3 D NiMoNbSi / Y 47.2 79.3 98.4 96.2 E NiMoNbBSi / Y 47.4 79.6 98.5 96.8 F NiMoNbBSiF / Y 47.6 79.7 98.7 97.0

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  The results of Table 3 show that the presence of a mixed molybdenum-niobium sulphide phase brings an improvement in the performance of the catalyst in HDS, HDN. This is due to the better activity of the mixed sulfide phase compared to that of catalyst C not containing this phase. The A5 conversion performance is equivalent while the raw selectivity for middle distillates is improved due to a more hydrogenating phase. When adding a promoter chosen from the group P, B, Si, optionally fluorine, a slight improvement in the conversion and an improvement in the selectivity are observed. The catalysts based on dealuminated Y zeolite of the invention containing a mixed sulphide phase containing at least one element of group VB and at least one element of group VIB are therefore particularly advantageous for the partial hydrocracking of charge of distillate type under vacuum containing nitrogen at moderate hydrogen pressure. They are further improved by the presence of at least one promoter chosen from the group P, B, Si, F. Example 6: Comparison of the hydrocracking catalysts of a gas oil under vacuum with high conversion The catalysts whose preparations are described in previous examples are used under the conditions of high conversion hydrocracking (60-100%). The petroleum charge is a hydrotreated vacuum distillate, the main characteristics of which are as follows: Density (20/4) 0.869 Sulfur (ppm weight) 502 Nitrogen (ppm weight) 10 Simulated distillation initial point 298 C point 10% 369 C point 50% 427 C point 90% 481 C final point 538 C This charge was obtained by hydrotreating a distillate under vacuum on an HR360 catalyst sold by the company Procatalyse comprising an element of

  group VI and an element of group VIII deposited on alumina.

29; ; 2780307

  0.6% by weight of aniline and 2% by weight of dimethyldisulphide are added to the charge in order to simulate the partial pressures of HS2 and NH3 present in the second hydrocracking step. The charge thus prepared is injected into the hydrocracking test unit which comprises a fixed bed reactor, with upward circulation of the charge ("up-flow"), into which 80 ml of catalyst is introduced. The catalyst is sulfurized by an n-hexane / DMDS + aniline mixture up to 320 C. It should be noted that any in-situ or ex-situ sulfurization method is suitable. Once the sulfurization has been carried out, the charge described above can be transformed. The operating conditions of the test unit are as follows Total pressure 9 MPa Catalyst 80 cm3 Temperature 360-420 C Hydrogen flow rate 80 I / h Charging flow rate 80 cm3 / h The catalytic performance is expressed by the temperature which allows '' reach a gross conversion level of 70% and by gross selectivity to distillates 150-380 C. These catalytic performances are measured on the catalyst after a stabilization period, generally at least 48 hours,

has been respected.

  The gross conversion CB is taken equal to: CB =% by weight of 380 minus the effluent The gross selectivity SB in middle distillate is taken equal to SB = 100 * weight of the fraction (1 50 C-380 C) / weight of the fraction 380m 0ns of the effluent The reaction temperature is fixed so as to reach a gross conversion CB equal to 70% by weight. In Table 4 below, we have reported the reaction temperature and the raw selectivity for the catalysts described in the

Tables 1 and 2.

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Table 4

  Catalytic activities of NiMo and NbNiMo catalysts in high conversion hydrocracking (70%)

T (C) SB

  A NiMo / Y 376 63.7 B NiMoNb / Y 374 65.3 C NiMoNb / Y (comparison) 376 63.9 D NiMoNbSi / Y 373 65.9 E NiMoNbBSi / Y 372 66.4 F NiMoNbBSiF / Y 370 66, 9 In comparison with catalyst C, the presence of a mixed molybdenum-niobium sulfide phase in the catalyst containing the dealuminized Y zeolite of the invention makes it possible to significantly improve the selectivity thanks to the better quality.

  of the hydro-dehydrogenating function constituted by the mixed sulphide phase.

  It is also observed that by adding Si, B and or F to the catalyst containing the mixed sulfide phase, the improvement in selectivity is preserved while increasing the activity in conversion, which results in a decrease in the

  reaction temperature required to reach 70% conversion.

  The catalysts of the invention containing a mixed sulphide phase comprising at least one element from the VB group and at least one element from the VB group are therefore particularly advantageous for hydrocracking with high charge conversion of

vacuum distillates type.

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Claims (18)

  1. Catalyst comprising at least one zeolite Y at least partially dealuminated, whose lattice parameter is between 2.424 nm and 2.455 nm, and whose overall SiO2 / AI203 molar ratio is greater than 8, at least one matrix chosen from the group formed by mineral matrices, at least one mixed sulphide phase comprising sulfur and at least one element from group VB as well as at least one element from group VIB, optionally at least one metal from group VIII and optionally at least one element chosen from the group formed by silicon, boron or phosphorus, and optionally at least one element from group VIIA of said classification.   2. Catalyst according to claim 1 such that the element of group VB is niobium.   3. Catalyst according to one of claims 1 or 2 such as the element of group VIB is molybdenum or tungsten.   4. Catalyst according to one of claims 1 to 3 comprising a sulfide phase mixed niobium and molybdenum.   5. Catalyst according to one of claims 1 to 4 comprising a sulfide phase   mixed of approximate general formula following Ax Bl-x Sy o: x is a number between 0.001 and 0.999, y is a number between 0.1 and 8, A is the element of the group VB,   B is the element chosen from group VIB.   6. Catalyst according to one of claims 1 to 4 comprising a sulfide phase   mixed with the following approximate general formula: Ax B1-x Sy o: x is a number between 0.05 and 0.95, y is a number between 0.5 and 4, A is an element of the group VB,   B is an element chosen from group VIB. 32 2780307   7. Catalyst according to one of claims 1 to 6 further comprising at least one   element of group VIII of the periodic table.   8. Catalyst according to claim 7 such that said metal from group VIII is chosen from the group formed by iron, cobalt, nickel and ruthenium.   9. Catalyst according to one of claims 1 to 8 in which the matrix is alumina.   10. Catalyst according to one of claims 1 to 9 further comprising at least   an element chosen from the group formed by silicon, boron or phosphorus.   11. Catalyst according to one of claims 1 to 10 further comprising at least an element of the VIIA group.   12. Catalyst according to one of claims 1 to 11 containing in% by weight by   relative to the total mass of the catalyst: - 0.1 to 99.9% of at least one matrix, - 0.1 to 99.8% of at least one Y zeolite at least partially dealuminated, including the mesh parameter is between 2,424 nm and 2,455 nm and whose ratio   overall SiO2 / AI203 molar is greater than 8.   - 0.1 to 99.5% of at least one mixed sulphide phase of at least one element of the group   VB and at least one element from group VIB.   the catalyst which can also contain: - from 0 to 30% of at least one metal from group VIII, - from 0 to 20% of at least one element chosen from the group formed by boron, phosphorus and silicon, and   - from 0 to 15% of at least one element chosen from the VIIA group.   13 - Process for the preparation of the mass mixed sulphide phase included in the   catalyst according to one of claims 1 to 12 comprising the following steps:   a) forming a reaction mixture which contains at least the following compounds at least one source of element of group VB, at least one source of element of group VIB, optionally water, optionally at least one source of a element chosen from the group formed by elements of group VIII, possibly 33 2780307   at least one source of an element chosen from the group formed by silicon, the   phosphorus and boron, optionally an element chosen from halogens, that is to say tell the elements of the VIIA group.   b) said mixture is maintained at a heating temperature generally greater than about 40 ° C., at a pressure at least equal to atmospheric pressure and in the presence of a sulfur compound until   obtains said mixed sulfide phase.   14. Process for the preparation of the supported mixed sulfide phase included in   catalyst according to one of claims 1 to 12 comprising the following steps:   a) a reaction mixture is formed which contains at least the following compounds at least one matrix chosen from the group formed by mineral matrices, preferably of oxide type, preferably amorphous or poorly crystallized and generally porous, at least one Y zeolite, at least partially dealuminated, whose mesh parameter is between 2,424 nm and 2,455 nm, and whose overall SiO2 / AI203 molar ratio is greater than 8, at least one source of element of group VB, at least one source of element from group VIB, optionally water, optionally at least one element chosen from the group formed by elements from group VIII, optionally at least one source from an element chosen from the group formed by silicon, phosphorus and boron,   optionally at least one source of an element chosen from halogens, that is   ie the elements of the VIIA group.   b) said mixture is maintained at a heating temperature generally above about 40 C in the presence of a sulfur compound until a solid is obtained containing at least one matrix, at least one Y zeolite   dealuminated and at least one mixed sulfide phase.   15. Method according to one of claims 13 or 14 as one proceeds to the   sulfurization of the mixture at a temperature between 40 and 700, under pressure autogenous, and in the presence of CS2.   16. Use of the catalyst according to one of claims 1 to 12 or prepared according to   one of claims 13 to 15 in hydrocracking of hydrocarbon feedstocks. 34 2780307   17. Use according to claim 16 in which the temperature is greater than C, the pressure is greater than 0.1 MPa, the volume of hydrogen per volume of charge is at least 50 liters of hydrogen per liter of charge and the an hourly volume speed is between 0.1 and 20 charge volumes per volume of catalyst per hour.   18. Use according to one of claims 17 such that the filler is chosen from   the group formed by gasolines, gas oils, gas oils under vacuum, deasphalted residues or not, paraffinic oils, waxes and paraffins and it can   contain heteroatoms such as sulfur, oxygen and nitrogen and at least one metal.