FR2780306A1 - Hydrocracking catalyst for production of light petroleum fractions from heavy residues - Google Patents

Abstract

The catalyst may include mixed sulfide phases containing sulfides of groups VB and VIB elements to increase the acidity of the matrix and improve selectivity in middle distillates. The catalyst comprises an amorphous matrix of oxide-type, a group VB element, a beta zeolite, a promoter element (boron, phosphorus or silicon) and a group VIB or VIII element. In addition a catalyst is claimed comprising a beta zeolite, a mineral matrix, a mixed sulfide phase containing sulfur and metals of groups VB and VIB and optionally a group VIII metal, silicon, boron or phosphorus and a group VIIA element. An Independent claim is also included for the preparation of the catalyst by: (a) drying and weighing of a precursor solid containing a matrix, a beta zeolite, and optionally the promoter element, group VIB or VIII elements and group VIIa element, the whole being formed; (b) calcining the dry solid at a minimum of 150 deg C; (c) impregnating the calcined solid with a solution containing a group VB element, preferably niobium; (d) leaving the moist solid in a moist atmosphere at 10-120 deg C; (e) drying the moist solid at 60-150 deg C; and (f) calcining the dried solid at a minimum of 150 deg C, preferably 250 deg C. The catalysts is sulfurized in a mixture of H2 / H2S or pure H2S at 150 - 800 deg C.

Description

The present invention relates to a hydrocracking catalyst

  hydrocarbon compounds, said catalyst comprising at least one zeolite beta, at least one matrix selected from the group formed by the mineral matrices, preferably of the oxide type, preferably amorphous or poorly crystallized and generally porous, at least one mixed sulfur phase comprising sulfur and at least one element of group VB of the periodic table of 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 front cover), such as tantalum, niobium and vanadium, preferably niobium, and at least one element of group VIB of this classification (group 6), such as chromium, molybdenum or tungsten, preferably molybdenum and tungsten. , even more preferably

molybdenum.

  The catalyst according to the invention may furthermore optionally comprise at least one metal of group VIII of said classification (groups 8, 9 and 10), such as iron, cobalt, nickel, ruthenium, osmium, rhodium, iridium, palladium, platinum, and optionally at least one element selected from the group formed by silicon, boron or phosphorus, and optionally at least one element of group VIIA of 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 the hydrocracking of hydrocarbon feeds such as petroleum cuts, cuts derived from carbon containing aromatic compounds, and / or olefinic and / or naphthenic, and or paraffinic, said charges possibly containing metals, and / or nitrogen, and / or

oxygen and / or sulfur.

  Hydrocracking of heavy oil cuts is a very important process of refining which makes it possible to produce, from excessively heavy and unrecoverable heavy loads, the lighter fractions such as gasolines, fuels and light gas oils that the refiner seeks in order to adapt his production to the structure of the request. Certain hydrocracking processes also make it possible to obtain a highly purified residue that can constitute excellent bases for oils. With respect to catalytic cracking, the interest of catalytic hydrocracking is to provide

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  middle distillates, jet fuels and gas oils, of very good quality. The gasoline produced has a much lower octane number than that resulting from catalytic cracking. The catalysts used in hydrocracking are all of the bifunctional type associating an acid function with a hydrogenating function. The acid function is provided by supports with large surface areas (generally 150 to 800 m2. G) with superficial acidity, such as halogenated aluminas (in particular chlorinated or fluorinated), and combinations of boron and aluminum oxides. , amorphous silica-aluminas and clays. The hydrogenating function is provided either by one or more metals of group VIII of the periodic table of the elements, such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a combination of at least one Group VI metal of the periodic table such

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

  The equilibrium 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 low active catalysts, working at a generally high temperature (greater than or equal to 390 ° C.), and at a low feed space velocity (the VVH expressed in volume of charge to be treated per unit volume of catalyst and per hour is generally less than or equal to 2) but endowed with a very good selectivity in middle distillates Conversely, a strong acid function and a low hydrogenating function give active catalysts but having less good selectivities The search for a suitable catalyst will therefore be centered on a judicious choice of each of the

  functions to adjust the catalyst activity / selectivity couple.

  Thus, it is one of the great interests of hydrocracking to have great flexibility at various levels: flexibility in the catalysts used, which leads to a flexibility of the feeds to be treated and to the level of the products obtained. An easy parameter to

  to control is the acidity of the catalyst support.

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

bases oils.

  In low acid carriers, there is the family of amorphous silica-aluminas. Many of the hydrocracking market catalysts are based on silica-alumina associated with either a Group VIII metal or, preferably, when the heteroatomic content of the feedstock to be treated exceeds 0.5 wt. combination of Group VIB and VIII metal sulphides. These systems have a very good selectivity in middle distillates, and the products formed are of good quality. These catalysts, for the less acidic of them, can also produce lubricating bases. The disadvantage of all these catalytic systems to

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

  On the other hand, simple sulfides of Group VB elements have been described as components of hydrorefining catalysts for hydrocarbon feeds, such as niobium trisulphide in US Pat. No. 5,294,333. Mixtures of simple sulfides comprising at least one group VB element and a group VIB or group VIII element have also been tested as hydrocarbon feedstock hydrorefining catalyst components, for example in

  US-A-4,871,445, US-A-4,910,181 or US-A-5. 275,994.

  The research work carried out by the applicant on the zeolites and the hydrogenating active phases led him to discover that, surprisingly, a hydrocracking catalyst of hydrocarbon feeds comprising at least one matrix chosen from the group formed by the matrices. inorganic, preferably oxide, preferably amorphous or poorly crystallized and generally porous such as alumina, at least one zeolite beta, and at least one mixed sulphide phase. This catalyst may also optionally contain at least one element of group VIII, optionally an element selected from the group formed by silicon, phosphorus and boron, optionally at least one element selected from group VIIA.

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  The catalyst according to the invention contains at least one zeolite beta, preferably at least partially in the hydrogen form. Zeolite beta is understood to mean zeolites of structural type BEA as described in the work, Atlas of Zeolite Structure Types, WM Meier, DH Oison and Ch. Baerlocher, 4 "revised edition, 1996, Elsevier. The mixed compound present in the catalyst according to the invention is characterized by the following generalized formula: ## STR1 ## where 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, 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 group VB, such as tantalum, niobium or vanadium, preferably niobium, B is a member selected from group VIB, such as chromium, molybdenum or tungsten, preferably molybdenum or tungsten, more preferably

preferred molybdenum.

  The catalyst according to the invention is in supported form, that is to say that it comprises at least one support consisting of at least one matrix, for example of the oxide type,

  for example alumina, and at least one beta zeolite.

  The catalyst according to the present invention generally comprises, in% by weight with respect to the total mass of the catalyst: from 0.1 to 99.9%, preferably from 1 to 99.5% and even more preferably from 5 to 99.0%. at least one matrix, preferably of 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 zeolite beta, the overall atomic ratio, silicon / aluminum (Si / Al) is preferably greater than about 10, more preferably between 10 and 200, and still more

  most preferred between 10 and 150.

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  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 group VB and from

least one element of group VIB.

  the catalyst may additionally contain: 0 to 30%, preferably 0 to 25% and even more preferably 0.1 to 20% of at least one Group VIII metal, 0 to 20%, preferably 0 to 15%, and more preferably 0.1 to 15% of at least one member selected from the group consisting of boron, phosphorus and silicon, and 0 to 15%, preferably 0 to 15%, preferably , 1 to 15% and more preferably 0.1 to 10%

  at least one member selected from group VIIA, preferably fluorine.

  The matrix is preferably chosen from the group formed by the mineral matrices, preferably the porous mineral matrices, preferably amorphous or poorly

  crystallized, and preferably oxide type.

  The identification of the mixed sulphide phase is generally done from the X-ray diffraction pattern. It can also be done from the determination of the metal-to-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 sulphide, EXAFS identification is done by determining niobium-niobium or niobium-molybdenum distances if EXAFS is performed at the K-threshold of niobium. It can also be done by determining the molybdenum-molybdenum and molybdenum-niobium distances if

  the EXAFS analysis is performed at the threshold K of molybdenum.

  The diffraction pattern X is obtained using an INEL multi-detector curved diffractometer using the conventional powder method with monochromatic K alpha 1 copper radiation. From the position of the diffraction peaks represented by the 2 theta angle, the Bragg relation is used to calculate the characteristic dhkl lattice distances of the sample and the mesh parameters of the mixed phase a and c at A ( 1A = 1 Angstrom = 10'1m). The mesh 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 diffraction structure can also be determined. Thus, for example, in the case of a mixed sulphide of molybdenum and niobium, the simple sulphides of Mo and Nb, MoS2 and NbS2, exist

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  both in the form of two types of structure the hexagonal form 2s and the rhombohedral form 3s. For molybdenum-rich samples (x <0.5) the mixed phase tends to crystallize in the 2s hexagonal structure type and the mesh parameters vary linearly as a function of the niobium proportion of the mixed phase as shown in Table 1 For samples rich in niobium (x ≥ 0.5), the mixed phase tends to crystallize in the 3s rhombohedral structure and the mesh parameters also vary linearly with the composition

  in niobium as shown in Table 2.

  The estimation of the measurement error Delta (dhkl) on 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 from the area of the peak of

corresponding diffraction.

TABLE 1

  Phase a (A) c (A) MoS2-2s 3.16 12.29 Nb0.2Mo0.8S2 3.20 12.05 Nbo, 3Mo0.5S2 3.22 12.02 Nbo, 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 Nb 0.6Mo0.4S2 3.25 18.00 Nb0.7Mo0.3S2 3.27 17.98 Nb0.8Moo, 2S2 13.30 17, 97 NbS2-3s 3.33 17.81

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  The stripping of the X-ray diffraction pattern in the form of the mesh parameters presented in Tables 1 and 2 makes it possible to identify the mixed niobium and molybdenum sulphide. The EXAFS analysis is performed at the niobium K threshold. using synchrotron radiation between 18850 and 19800 eV by measuring the intensity absorbed by a powder sample deposited on an adhesive tape. The absorption spectrum is analyzed according to an established procedure (F. W. Lyttle, D. E. Sayers and E. A. Stern,

  Physical Review B, Vol. 11, p. 4825, 1975 and E. A. Stern, D.E. Sayers and F.W.

  Lyttle, Physical Review B, vol. 11, page 4836) which makes it possible to determine the interatomic distances. The stripping of the X-ray adsorption spectrum makes it possible to deduce a radial distribution function. This radial distribution shows a first peak relative 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 λ typical of NbS2. Then we observe on this radial distribution a second peak corresponding to the second coordination sphere of niobium composed of niobium or molybdenum atoms that can not be distinguished because of their very close atomic numbers.

  no and whose position of the maximum gives the average distance R2 metalmetal (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 is between the values

  the niobium-niobium distance in NbS2 (3.33 À) and the molybdenum-distance

  molybdenum in MoS2 (3.16 A), and it is generally on average 3.20 to 3.35 A. This distance is in agreement with the distances determined by X-ray diffraction and varies with the composition of the mixed phase. The distances reported in Table 3 are corrected for the phase shift and can therefore be compared with data obtained by X-ray diffraction. The determination of metal-metal interatomic distances by the EXAFS technique is very precise since the estimation of the error

  absolute over the distance is equal to + 0.02 Å.

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TABLE 3

  R1 (A) R2 (A) Nbo, 2Mo0.8S2 2.46 13 NbO, 3Mo0.7S2 2.45 3.22 NbO, 4Mo0.6S2 2.48 3.27 Nbo, 6Mo0, 4S2 2.47 , 28 Nbo, 7Mo0, 3S2! 2.47 3.30 Nbo, 8Mo0.2S2 2.48 3.31 NbS2 2.48 3.33 The catalyst according to the invention can be prepared either by firstly preparing a phase mass-mixed sulphide and then depositing it on a support, either directly generating a catalyst precursor consisting of a supported mixed sulphide phase. The optional elements that may be present (group VIII elements, elements chosen from the group formed by silicon, phosphorus and boron, elements of group VIIA) may 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 method of preparing the mixed-mass sulfide phase included in the catalyst according to the present invention comprises the following steps: a) forming a reaction mixture which contains at least the following compounds at least one source of group VB element, at at least one source of group VIB element, optionally water, optionally at least one source of an element selected from the group formed by the elements of group VIII, optionally at least one source of an element selected from the group formed by silicon, the

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

  group VIIA elements, preferably fluorine, 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 up to to what we get

said mixed sulphide phase.

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

  sulfuration known to those skilled in the art.

  In fact, the sulfurization of solids containing at least one element of group VB in the form of oxide 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 the group VB supported on an alumina-type matrix are known to be very difficult to sulphurize, once the combination element of the VB-matrix group

  was 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 in a pressure autoclave. Thus, a preferred method according to the invention consists in carrying out the sulphidation of the mixture, generally in the form of powder solids, at a temperature of between 40 and 7000 ° C., preferably between 60 ° and 500 ° C., under autogenous pressure and in the presence of a gaseous compound of sulfur such as

preferably CS2.

  An autoclave internally coated with a polymeric material, usually polytetrafluoroethylene, is preferably used at a temperature greater than 100 ° C. The duration of the heating of the reaction mixture necessary for the sulphurization depends on the composition of the reaction mixture and on the temperature of the reaction mixture. 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 EP-A-440.516 for the synthesis of a binary sulfur compound, that is to say a simple sulfur containing sulfur and another element, transition metal or rare earth, has been found applicable for the synthesis of mixed sulphides

according to the present invention.

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

possible are described below.

  In general, it is possible to mechanically mix the zeolite beta and the matrix generally in powder form with any precursor of the mixed sulphide phase, and then proceed to the sulphidation, as is described in more detail below. It is also possible to carry out a mechanical mixture comprising, on the one hand, the mixed sulphide powder, synthesized according to one of the methods described previously, and on the other hand the support (that is to say a mixture of matrix and zeolite) also in powder form, and then possibly proceed to a shaping. In all cases it is possible in principle 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.

  One of the preferred processes for preparing the supported mixed sulphide 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 oxide type, preferably amorphous or poorly crystallized and generally porous, at least one zeolite beta, at least one source of element of group VB, at least one source of element of group VIB, optionally water, optionally at least one element selected from the group consisting of group VIII elements, optionally at least one source of a member selected from the group consisting of silicon, phosphorus and boron, optionally at least one source of an element chosen from halogens, that is to say the elements of group VIIA, preferably fluorine, b) said mixture is maintained at a temperature of a heating compound generally greater than about 40 C in the presence of a sulfur compound until a solid containing at least one matrix, at least one zeolite beta and at least one

at least one mixed sulphide phase.

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  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 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, by ammonium heptamolybdate, to carry out a drying at 80 C, then to impregnate with niobium oxalate, to proceed to a drying at 80 C, and to carry out a sulfurization for example and preferably by CS2 autoclave under autogenous pressure, as described for the preparation of the mixed sulphide phase

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

  It is also possible to carry out the mixture of powders comprising the element source of the group VB, the group VIB element source, optionally water, optionally the source of the element chosen from silicon, phosphorus and boron, possibly the source of the group VIIA element and possibly the source of sulfur and impregnate the support. It is also possible to impregnate the matrix alone and add the zeolite beta thereafter, by any means known to the man of the

  profession, for example by mechanical mixing.

  When the matrix is impregnated, impregnation of the matrix is preferably carried out by the so-called "dry" impregnation method well known to those skilled in the art. The impregnation can be carried out in a single step by 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 pelletization, the oil-drop method, a rotating plate granulation or any other well-known method of the invention. skilled person. The preformed support is optionally calcined under air, usually at a temperature

  at least 300 C, commonly from about 350 to 1000 C.

  The mixed sulphide phase, as well as the element of group VIII, as well as the element selected from the group consisting of P, B and Si and the element selected from group VIIA of the halides, preferably fluorine, may to be introduced in the

  catalyst at various levels of preparation and in various ways.

  The mixed sulphide phase may be introduced only in part (for example, in the case of the combination of at least one Group VB and / or Group VIB metal and at least one Group VIII metal) or in totality. at the time of mixing of the porous matrix,

  optionally with all or part of the zeolite.

  The Group VIII metal as well as the element selected from the group consisting of P, B, Si and the element selected from group VIIA halides can be introduced by one or more ion exchange operations on the calcined matrix. composed of mixed sulphide 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 impregnation operation of the shaped and calcined support, with a precursor solution of at least one Group VIII metal (in particular cobalt and / or nickel), any precursor of metal of the group VIII being preferably introduced in

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

  In the case where the metals are introduced in several impregnations, corresponding precursor salts, an intermediate catalyst drying step 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. It is also possible to choose aluminates. It is preferred to use matrices containing alumina, in all these forms known to the human being.

  occupation, for example gamma alumina.

  Of the beta zeolites, it is generally preferred to employ beta zeolites whose overall silicon / aluminum (Si / Al) atomic ratio is greater than about 10 and more preferably beta zeolites whose Si / Al ratio is between 10 and , and even more preferably between 10 and 150. These beta zeolites can

  be obtained by synthesis or by using any post-dealumination technique.

  synthesis known to those skilled in the art.

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  Zeolites beta are advantageously used, either entirely in the hydrogen form, or possibly partially exchanged with metal cations, for example alkali or alkaline earth metal cations and / or rare earth cations of atomic number 57 to 71 inclusive (Zeolite Molecular Sieves Structure, Chemistry and Uses, Breck DW, Willey J. and sons, 1973). The cation / Al atomic ratio is in general less than 0.8, preferably less than 0.5 and even more preferably less than 0.1. The beta zeolites according to the invention preferably have a specific surface area determined by the B.E.T. better than

  about 400 m2 / g, and more preferably between 450 and 850 m2 / g.

  Group VB element sources 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 Nb 2 Os 5, niobic acid Nb 2 O 5 .H 2 O, niobium hydroxides and polyoxoniobates, niobium alkoxides of formula Nb (OR 1) 3 R1 is an alkyl radical, niobium oxalate NbO (HC204) 5, ammonium niobate. Niobium oxalate or ammonium niobate is preferably used. Sources of Group VIB elements that 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, molybdenum 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, ammonium heptamolybdate and

ammonium tungstate.

  The source of sulfur may be elemental sulfur, carbon disulfide, hydrogen sulphide, sulfur-containing hydrocarbons such as dimethyl sulphide, dimethyl disulfide, mercaptans, thiophene compounds, thiols, polysulphides such as, for example the ditertiononylpolysulfide or TPS-37 from ATOCHEM, sulfur-rich petroleum cuts such as gasoline, kerosene, diesel, alone or in mixtures with one of the sulfur compounds mentioned above. The source of sulfur

  preferred is carbon disulfide or hydrogen sulphide.

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  The preferred phosphorus source is phosphoric acid H 3 PO 4, but its salts and esters such as alkaline phosphates, ammonium phosphates, gallium phosphates or alkyl phosphates are also suitable. The phosphorus may 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 the family of the

  pyridine and quinolines and compounds of the pyrrole family.

  Many sources of silicon can be used. Thus, ethyl orthosilicate Si (OEt) 4, siloxanes, polysiloxanes, silicones, silicone emulsions, halide silicates such as ammonium fluorosilicate (NH 4) 2 SiF 6 or fluorosilicate can be used. sodium Na2SiF6. Silicomolybdic acid and its salts, silicotungstic acid and its salts can also be advantageously employed. The silicon may be added, for example, by impregnation of ethyl silicate in solution in a water / alcohol mixture. Silicon may also be added, for example, by impregnation of a silicon compound

  silicone type suspended in water.

  The source of boron may be boric acid, preferably orthoboric acid 2o H3BO3, biborate or ammonium pentaborate, boron oxide, boric esters. The boron may 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 family of pyridine and quinolines and compounds of the pyrrole family. Boron can be introduced for example by means of an acid solution

  boric acid in a water / alcohol mixture.

  Sources of VIIA group elements that can be used are well known to those skilled in the art. For example, the fluoride anions may 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 the 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 tetrafluoride Na2SiF6. The

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  fluorine can be introduced for example by impregnation of an aqueous solution of acid

  hydrofluoric or ammonium fluoride.

  The catalyst of the present invention may include a Group VIII element such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium or platinum. Among the Group VIII metals, it is preferred to employ a metal selected from the group consisting of iron, cobalt, nickel and ruthenium. Advantageously we

  uses the following combinations of metals: nickel-niobium-molybdenum, cobalt-

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

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

  niobium-molybdenum, cobalt-niobium-molybdenum. It is also possible to use combinations of four metals, for example nickel-cobaltniobium-molybdenum. We

  can also use associations containing a noble metal such as ruthenium-

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

  The impregnation of molybdenum can be facilitated by the addition of phosphoric acid in the ammonium paramolybdate solutions, which also makes it possible to introduce the phosphorus so as to promote the 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 shapes and sizes. They are generally used in the form of cylindrical or multi-lobed extrusions such as bilobed, trilobed, straight or twisted polylobed, but may optionally be manufactured and used in the form of crushed powder, tablets, rings, beads. , 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 about 50 and about 600 m2. / g, a porous volume measured by mercury porosimetry of between about 0.2 and about 1.5 cm3 / g and a size distribution of

  pores can be monomodal, bimodal or polymodal.

  The catalysts obtained by the present invention are used for the hydrocracking of hydrocarbon feeds such as petroleum cuts. The feedstocks used in the process are gasolines, kerosenes, gas oils, vacuum gas oils, atmospheric residues, vacuum residues, atmospheric distillates, vacuum distillates, heavy fuels, oils, waxes and paraffins, used oils, residues or deasphalted crudes, fillers derived from thermal or catalytic conversion processes and mixtures thereof. 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 fractions of vacuum distillate type, deasphalted or hydrotreated residues or the like. The heavy cuts preferably consist of at least 80% by volume of compounds whose boiling points are at least 350 ° C. and preferably between 350 ° and 580 ° C. (that is to say corresponding to compounds containing at least 15 to 20 carbon atoms). They usually 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 space velocity, may be very variable depending on the nature of the load, the quality of desired products and facilities available to the refiner. The temperature is in general greater than 200 C and preferably between 250 C and 480 C. The pressure is greater than 0.1 MPa and preferably greater than 1 MPa. The amount of hydrogen is at least 50 and often between 80 and 5000 normal liters of hydrogen per liter of charge. The hourly volume velocity is in general between 0.1 and 20

  volume of charge per volume of catalyst per hour.

  The catalysts of the present invention are optionally subjected to a complementary sulfurization treatment before being employed in the hydrocracking reaction. This treatment makes it possible, at least in part, to transform the residual metal species into sulphide before they come into contact with the charge to be treated. This activation treatment by sulphurisation is well known to the French

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

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

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

to bed crossed.

  The catalyst of the present invention can be advantageously employed for the hydrocracking of vacuum distillate type cuts which are highly charged with sulfur and nitrogen, for example, cuts 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 still called mild hydrocracking, the conversion level is less than 55%. The catalyst according to the invention is then employed at a temperature in general 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 being greater than 2 MPa. more preferably 3 MPa, and preferably less than 12 MPa, more preferably less than 10 MPa. The amount of hydrogen is at least 100 normal liters of hydrogen per liter of filler, and preferably between 200 and 3000 normal liters of hydrogen per liter of filler. The hourly volume velocity is preferably between 0.15 and 10 volume of charge per volume of catalyst per hour. Under these conditions, the catalysts of the present invention have a better activity in conversion, in hydrodesulphurization and in

  hydrodenitrogenation as commercial catalysts.

  In a second embodiment, the catalyst of the present invention may be used for partial hydrocracking, advantageously under moderate hydrogen pressure conditions, for example, vacuum-type vacuum distillate fractions which are heavily loaded with sulfur and nitrogen which have previously hydrotreated. In this hydrocracking mode, the conversion level is less than 55%. In this case, the petroleum fraction conversion process takes place in two stages, the catalysts according to the invention being used in the second stage. The catalyst of the first step has a hydrotreatment function and comprises a matrix preferably of alumina base, and preferably containing no zeolite, and at least one metal having a hydrogenating function. Said matrix is an amorphous or poorly crystallized porous mineral matrix of the oxide type. Nonlimiting examples include aluminas, silicas, silica-aluminas. It is also possible to choose aluminates. It is preferred to use matrices containing alumina, in all these forms known to those skilled in the art, and even more preferably aluminas, for example

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  gamma alumina. The hydrotreatment function is provided by at least one metal or group VIII metal compound such as nickel and cobalt in particular. A combination of at least one metal or group VIB metal compound (for example, molybdenum or tungsten) and at least one metal or group VIII metal compound (eg, cobalt or nickel) may be used of the periodic table of 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 Group VIB metal oxide (metals). Group VIII metal oxide (metals)

  Io 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 the P 2 O 5 phosphorus pentoxide concentration, 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 may also contain boron in a B / P ratio preferably between 1.05 and 2 (atomic), the sum of the boron (B) and phosphorus (P) contents expressed in oxides being

  preferably between 5 and 15% by weight.

  The first step generally takes place at a temperature of between 350 and 460 ° C., preferably between 360 and 45 ° C., a total pressure of at least 2 MPa, preferably at least 3 MPa, an hourly space velocity of between 0.1 and The volume of charge per volume of catalyst per hour, preferably between 0.2 and 2 volume of charge per volume of catalyst 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 stage), the temperatures are generally greater than or equal to 230 ° C. and often between 300 ° C. and 480 ° C., and preferably between 300 ° C. and 450 ° C. The pressure is generally at least 2 MPa and preferably at least 3 MPa. The amount of hydrogen is at least 100 liters of hydrogen per liter of filler and preferably between 200 and 3000 liters of hydrogen per liter of filler. The hourly volume velocity is preferably between 0.15 and 10 volume of charge per volume of catalyst per hour. Under these conditions, the catalysts of the present invention have a better activity in conversion, hydrodesulfurization, hydrodenitrogenation and better selectivity in middle distillates than commercial catalysts. The lifetime of the catalysts is

  also improved in the moderate pressure range.

  In another embodiment, the catalyst of the present invention may be employed for hydrocracking under high hydrogen pressure conditions, generally at least 5 MPa. The treated slices are, for example, vacuum distillate type with a high sulfur and nitrogen load which have been previously hydrotreated. In this hydrocracking mode, the conversion level is greater than%. In this case, the oil cutting conversion process takes place in two

  steps, the catalyst according to the invention being used in the second step.

  The catalyst of the first step has a hydrotreatment function and comprises a matrix preferably based on alumina, and preferably containing no zeolite, and at least one metal having a hydrogenating function. Said matrix may 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 group VIII metal compound such as nickel and cobalt in particular. A combination of at least one metal or group VIB metal compound (for example, molybdenum or tungsten) and at least one metal or group VIII metal compound (eg, cobalt or nickel) may be used of the periodic table of 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 metal (or metals) of Group VIII 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 the phosphorus pentoxide P 2 O 5 concentration, 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 may also contain boron in a B / P ratio preferably between 1.02 and 2 (atomic), the sum of the boron (B) and phosphorus (P) contents expressed in

  oxides preferably being between 5 and 15% by weight.

  The first step generally takes place at a temperature of between 350 and 460 ° C., preferably between 360 ° and 450 ° C., a pressure of at least 2 MPa, preferably at least 3 MPa, a volume hourly velocity of between 0.1 and The volume of charge per volume of catalyst per hour, preferably between 0.2 and 2 volume of charge per volume of catalyst per hour and with a quantity 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 stage), the temperatures are in general 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 5 MPa and preferably greater than 7 MPa. The quantity of hydrogen is at least 100 liters of hydrogen per liter of feed and

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

  The hourly volume velocity is preferably between 0.15 and 10 volumes

  charge 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: Prenaration of a support containing a zeolite beta A hydrocracking catalyst support containing a zeolite beta was manufactured in large quantities so as to prepare different catalysts based on the same support. For this purpose, 18.9% by weight of a zeolite beta with a global Si / Al ratio (measured by X-ray fluorescence) of 23.1, an atomic ratio measured by atomic adsorption of Na / Al = 0.003, a BET surface area of 720 m2 / g and a pore volume of 0.298 ml of liquid nitrogen / g (at the temperature of liquid nitrogen) at P / Po = 0.14, which is mixed with 81.1% by weight of matrix composed of ultrafine tabular boebmite or alumina gel marketed under the name SB3 by Condéa Chemie Gmbh. This powder mixture was then mixed with an aqueous solution containing 66% nitric acid (7% by weight of acid per gram of dry gel) and kneaded for 15 minutes. At the end of this mixing, the paste obtained is

  passed through a die having cylindrical orifices of diameter equal to 1.4 mm.

  The extrudates are then dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours in moist air containing 7.5% of water. Cylindrical extrudates 1.2 mm in diameter, having a specific surface area of 286 m 2 / g, a pore volume of 0.39 cm 3 / g and a monomodal pore size distribution centered on 11 nm are thus obtained. Matrix analysis by X-ray diffraction reveals that it is composed of cubic gamma alumina of low crystallinity and

zeolite beta.

  EXAMPLE 2 Preparation of a Hydrocracking Catalyst Containing a Zeolite Beta and a Mixed Sulfide Phase (in Accordance with the Invention) The support extrudates containing a zeolite beta of Example 1 are impregnated dry with an aqueous solution of a mixture of ammonium heptamolybdate and nickel nitrate, dried overnight at 120 ° C. in air. The weight contents in oxides

  Catalyst A obtained are shown in Table 1.

  Catalyst A is impregnated with an aqueous solution of niobium oxalate Nb (HC 2 O 4), oxalic acid and ammonium oxalate. The aqueous solution containing niobium is prepared from 1330 ml of water in which it is dissolved

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

  To prepare the solution, the oxalic acid and ammonium oxalate mixture is first dissolved and when the solution is clear, the said solution is heated to 55 ° C. and the niobium oxalate is added. It is then filled 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 contacted with 380 g of catalyst. This allows to deposit about 5% by weight of Nb on the catalyst. After two hours, the extrusions are recovered. These are then dried overnight at 120 ° C. under a stream of dry air. The catalyst B obtained contains

  in particular 14.8% by weight of zeolite beta.

  Table 1: Characteristics of catalysts (after calcination for 2 hours at 500 ° C. under dry air) Catalyst IABCHIJ Nb2O5 (% wt) 0 4.7 4.9 4.6 4.4 4.7 MoO3 (wt%) 14 , 2 13.6 13.8 13.8 13.3 13.9 NiO (% wt) 3.5 3.3 3.5 3.3 3.2 3.3 r P205 (wt%) 0 0 0 W 5.1 0 B203 (% wt) 0 0 0 0 1.6 0 SiO2 (wt%) 15.0 14.3 14.8 15.3 14.2 14.7 F (wt%) 0 0 0 0 0 1,11 Supplement to. 100% 6, 100% Compliant | 67.3 64.3 63.0 63 58.2 62, 3 composed predominantly of A1203 (wt%) Blocked Zeolite (wt%) 15.5 14.8 14.3 14.3 13.4 14.4 Example 3 Preparation of Hydrocracking Catalysts Containing a Zeolite Beta and a Group VB Element (Not in Accordance with the Invention) A hydrocracking catalyst containing zeolite beta and niobium was synthesized. This preparation is carried out by comalaxing a mixture of ultrafine tabular boehmite or alumina gel sold under the name SB3 by Condéa Chemie GmbH, a zeolite beta as described above in Example 1, nickel nitrate, of niobium pentoxide and ammonium heptamolybdate. To form the paste, these sources are used so as to obtain a catalyst containing 16% by weight of zeolite beta, 61.5% by weight of alumina, 14% by weight of molybdenum oxide, and 3.5% by weight of nickel oxide. and 5% by weight of niobium oxide. At the end of this mixing, the paste obtained is passed through a die having cylindrical orifices of diameter equal to 1.4 mm. The extrudates are then dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours in humid air containing 7.5% of water. Catalyst C is obtained in the form of cylindrical extrusions

  1.2 mm in diameter, the contents of which are indicated in Table 1.

  Example 4 Preparation of hydrocracking catalysts containing a zeolite beta, a mixed sulphide phase and at least one promoter element (according to the invention) We impregnated the catalyst sample A with an aqueous solution containing the emulsion of Rhodorsil EP1 silicone so as to deposit about 1.6% by weight of SiOC. After maturation at room temperature in an atmosphere saturated with water, the impregnated extrudates are dried overnight at C and then calcined at 550 ° C. for 2 hours under dry air. A catalyst named D is obtained. The support extrudates containing a beta zeolite of Example 1 are impregnated dry with an aqueous solution of a mixture of ammonium heptamolybdate, nickel nitrate and orthophosphoric acid, dried. one night at 120 C under air and

  finally calcined in air at 550 ° C. Catalyst E is thus obtained.

  We impregnated the catalyst sample E with an aqueous solution containing ammonium biborate and Rhodorsil EP1 silicone emulsion so as to deposit about 1.7% by weight of BOO3 and 1.5% by weight of SiO2. After maturation at ambient temperature in an atmosphere saturated with water, the impregnated extrudates are dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours under dry air. A catalyst named F is obtained. A fluorine-containing catalyst is also prepared by impregnating a dilute hydrofluoric acid solution of catalyst A so as to deposit about 1% by weight of fluorine. After drying overnight at 120 ° C. and calcining at 550 ° C. for 2 hours in dry air, catalyst G is obtained. Catalysts D and F are then impregnated with an aqueous solution of niobium oxalate Nb (HC.sub.2 O.sub.4). oxalic acid and ammonium oxalate. The aqueous solution containing niobium is prepared from 1330 ml of water in which it is dissolved

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

  To prepare the solution, the mixture is first dissolved oxalic acid and ammonium oxalate and when the solution is clear heating said solution to 55 C and niobium oxalate added. It is then filled with water to obtain 1330 ml of solution. The catalysts D and F are impregnated by the so-called excess solution method. The 1330 ml of solution are contacted with 380 g of catalyst. This allows to deposit about 5% by weight of Nb on the catalyst. After two hours, the extrusions are recovered. These are then dried overnight at C under a stream of dry air. Catalyst H is obtained from catalyst D.

  It contains in particular Nb and silicon.

  Catalyst I is obtained from catalyst F. It contains, in particular, Nb, phosphorus, silicon and boron. Fluorine is then added to this catalyst by impregnation with a hydrofluoric acid solution diluted so as to deposit about 1% by weight of fluorine. After drying overnight at 120 ° C. in dry air, catalyst J is obtained. The characteristics of catalysts H, I and J are

summarized in Table 1.

  EXAMPLE 5 Comparison of the Sulphide Catalysts In the catalysts B, C, H, I and J prepared above were sulphides in an autoclave under autogenous pressure in the presence of CS2. For 100 g of catalyst is added 20 ml of CS2 in the autoclave, is closed and heated at 400 C for 10 hours. The

  internal pressure is then about 4 MPa. This sulphurization is called S1.

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

  for 6 hours. This sulphurization is called S2.

  EXAFS analysis at the K-threshold of niobium is then carried out using synchrotron radiation between 18850 and 19800 eV by measuring the intensity absorbed by a powder sample deposited on an adhesive tape. It makes it possible to determine the interatomic distances. The distances R2 measured by EXAFS> (for catalyst samples B, C, H, I and J respectively sulphured by

  method S1 and method S2 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 (B, H, I and J) have a metal-metal distance R2 of the sulphide phase is lower than that of the catalyst C. The R2 value of 3.32 A for the catalyst C

3.5 2780306

  indicates that in this catalyst the niobium is in the form of a NbS2 phase identical to that of a catalyst which contains only niobium alone. The metal-metal distance R2 of 3.20 A or 3.21 A intermediate between the value of NbS2 and MoS2 indicates the presence of a mixed phase of niobium and molybdenum in the catalysts B, H, I and J.

Table 2

  Catalyst Catalytic sulphide by R2 (A) sulphide by R2 (A) method Si method S2

B-S1 3.20 B-S2 3.21

i C-Si 3.32 C-S2 3.32

H-S1 3.19 H-S2 3.20

I-S1 i 3.21 i I-S2 3.20

J-S1 3.21 J-S2 3.21

  Example 6 Comparison of the hydrocracked catalysts of a vacuum gas oil with

partial conversion.

  The catalysts whose preparations are described in the preceding examples are used under the conditions of hydrocracking at moderate pressure on a petroleum feed whose main characteristics are as follows Density (20/4) 0.921 Sulfur (% wt) 2.46 Nitrogen (ppm weight) 1130 Simulated distillation point in 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, In the first reactor, the one in which the feedstock passes first, is introduced the first hydrotreating catalyst HTH548 sold by the company Procatalyse comprising a group VI element and a group VIII element deposited on alumina In the second reactor, the one in which the feedstock passes last, a hydrocracking catalyst described above is introduced. 40 ml of catalyst are introduced. Both reactors operate at the same temperature and pressure. The operating conditions of the test unit are as follows: Total pressure 5 MPa Hydroprocessing catalyst 40 cm3 Hydrocracking catalyst 40 cm3 Temperature 400 C Hydrogen flow rate 20 I / h Charge rate 40 cm3 / h

  Both catalysts undergo an in situ sulphurization step prior to reaction.

  It should be noted that any in situ or ex situ sulphurization method is suitable. Once

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

  The catalytic performances are expressed by the gross conversion at 400 C (CB), by the crude selectivity in middle distillates (SB) and by the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) conversions. These catalytic performances are measured on the catalyst after a period of stabilization,

  usually at least 48 hours, has been respected.

  The gross conversion CB is taken as equal to: CB =% of 380m of the effluent The fraction 380 less of the effluent signifying the part of the effluent

boiling below 380 C.

  The gross selectivity SB in middle distillates is taken as equal to: SB = 100 * weight of the fraction (150 C-380 C) / weight of the fraction 380m ins of the effluent

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  The conversion to hydrodesulfurization HDS is taken as: HDS = (Sinitial - Seffluent) / Sinitial * 100 = (24600 - Seffluent) / 24600 * 100 The conversion to hydrodenitrogenation HDN is taken equal to HDN = (Ninitial Neffluent) / Ninitial * 100 = (1130 - Neffluent) / 1130 * 100 In the following table 3, we have reported the gross conversion CB at 400 C, the gross selectivity SB, the conversion into hydrodesulfurization HDS and the conversion into

  hydrodenitrogenation HDN for the four catalysts.

  Table 3: Catalytic Activities of Catalysts in Partial Hydrocracking at 400 ° C.

CB SB HDS HDN

  (% wt) (%) | (%) (%) NiMo / Beta 49.0 66.0 96.95 94.1 B NbNiMo / Beta} 49.4 66.0 97.6 94.7 C (comparative) NbNiMo / Beta 49.4 65 , 2 97.0 94.2 H NbNiMoSi / Beta | 50.0 65.4 97.8 95.0 I NbNiMoPBSi / Beta 50.3 65.4 98.3 96.1 J | NbNiMoF / Beta | 50.7 65.8 98.7 96.3 The results in Table 3 show that the presence of a molybdenum-niobium mixed sulphide phase brings an improvement in the performance of the catalyst in HDS, HDN. This is due to the better activity of the mixed sulphide phase compared to that of catalyst C not containing this phase. Performance in conversion

  is also slightly improved.

  The presence of a promoter selected from the group P. B, Si and F leads to an improvement in the conversion while the crude selectivity to middle distillates

  decreases because of the increase of the conversion level as it is well cennu.

  The gain in HDS and HDN activity of catalysts containing a promoter, B, Si, P and F is also noted. The zeolite beta catalysts of the invention containing a mixed sulphide phase containing at least one element of group VB and at least one At least one Group VIB element is therefore of particular interest for partial hydrocracking of vacuum distillate type feedstocks containing nitrogen at a moderate hydrogen pressure. Example 7 Comparison of Hydrocracking Catalysts of a High Conversion Vacuum Diesel Fuel The catalysts whose preparations are described in the preceding examples are used under the conditions of high conversion hydrocracking (60-100%). The petroleum feed is a hydrotreated vacuum distillate whose main characteristics 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 end point 538 C This feedstock was obtained by hydrotreating a vacuum distillate on an HR360 catalyst sold by the company Procatalyse comprising a member of the group

  VI and a group VIII element deposited on alumina.

  0.6% by weight of aniline and 2% by weight of dimethyldisulphide are added to the feed in order to simulate the partial pressures of HS 2 and NH 3 present in the second hydrocracking step. The feed thus prepared is injected into the hydrocracking test unit which comprises a fixed-bed reactor with up-flow of the feed ("up-flow"), into which 80 ml of catalyst is introduced. The catalyst is sulphurized with an n-hexane / DMDS + aniline mixture up to 320 C. It should be noted that any in-situ or ex-situ sulphurization method is suitable. Once the sulphurization has been carried out, the charge described above can be transformed. The operating conditions of the test unit are as follows

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  Total pressure 9 MPa Catalyst 80 cm3 Temperature 360-420 C Hydrogen flow 80 I / h Charge rate 80 cm3 / h The catalytic performances are expressed by the temperature which allows to reach a gross conversion level of 70% and by the gross distillate selectivity averages 150-380 C. These catalytic performances are measured on the catalyst after a period of stabilization, generally at least 48 hours, has

* been respected.

  The gross conversion CB is taken as equal to: CB =% wt of 380m ins of the effluent The gross selectivity SB in middle distillate is taken equal to SB = 100 * weight of the fraction (150 C-380 C) / weight of the fraction 380 'ns of the effluent The reaction temperature is set so as to reach a gross conversion CB equal to 70% by weight. In the following table 4, we reported the temperature

  of reaction and crude selectivity for the catalysts described in Tables 1 and 2.

  Table 4: Catalytic Activities of High-conversion Hydrocracking Catalysts (70%)

_________ _T (C) 9 SB (%)

  A NiMo / beta 371 49.2 B NbNiMo / beta 369 51.7 C (comparative) NbNiMo / beta 371 49.9 H NbNiMoSi / beta 368 51.9 I NbNiMoPBSi / beta 367 52.6 J NbNiMoF / beta 365 53, Compared with the catalyst C, the presence of a mixed molybdenum-niobium sulphide phase in the catalyst containing the zeolite beta of the invention makes it possible to substantially improve the selectivity by virtue of 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 in the catalyst containing the mixed sulphide phase, the improvement in selectivity is maintained while increasing the activity in conversion, which results in a decrease in

  reaction temperature required to achieve 70% conversion.

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

vacuum distillate type.

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Claims (18)

  A catalyst comprising at least one beta zeolite, at least one matrix selected from the group consisting of mineral matrices, at least one mixed sulphide phase comprising sulfur and at least one member of group VB and at least one member of the group VIB, optionally at least one group VIII metal and optionally at least one element selected from the group formed by silicon, boron or phosphorus, and optionally at least one element of group VIIA of said classification.   Catalyst according to claim 1, wherein 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 mixed sulphide phase of niobium and molybdenum.   5. Catalyst according to one of claims 1 to 4 comprising a mixed sulphide phase   no20 of the following approximate general formula: Ax B1-x Sy or: x is a number between 0.001 and 0.999, y is a number between 0.1 and 8, A is the element of group VB,   B is the element chosen in group VIB.   6. Catalyst according to one of claims 1 to 4 comprising a mixed sulphide phase   of the following approximate general formula: Ax B.-x Sy or: x is a number between 0.05 and 0.95, y is a number between 0.5 and 4, A is an element of group VB,   B is a member selected from group VIB. 32, 2780306   7. Catalyst according to one of claims 1 to 6 further comprising at least one   element of group VIII of the Periodic Table of Elements.   The catalyst of claim 7 wherein said Group VIII metal is selected from the group consisting of iron, cobalt, nickel and ruthenium.   9. Catalyst according to one of claims 1 to 8 wherein the matrix is alumina.   10. Catalyst according to one of claims 1 to 9 further comprising at least one   I0 element chosen from the group formed by silicon, boron or phosphorus.   Catalyst according to one of Claims 1 to 10, furthermore comprising at least an element of group VIIlA.   12. Catalyst according to one of claims 1 to 11 containing in% by weight   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 zeolite beta, whose mesh size is between 2.424 nm and 2.455 nm and whose overall SiO 2 / Al 2 O 3 molar ratio is greater at 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 of group VIB.   the catalyst may additionally contain: from 0 to 30% of at least one Group VIII metal, from 0 to 20% of at least one element selected from the group formed by boron, phosphorus and silicon, and   from 0 to 15% of at least one element chosen from group VIIA.   13 - Process for the preparation of the mixed mixed sulphide phase included in the   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 source of group VB element, at least one source of group VIB element, optionally water, optionally at least one source of a element chosen from the group formed by the elements of group VIII, optionally at least one source of an element chosen from the group formed by silicon, the 33 2780306   phosphorus and boron, optionally an element chosen from halogens, that is to say say 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   obtain said mixed sulphide phase.   14. Process for preparing the supported 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 matrix selected from the group formed by the mineral matrices, preferably oxide type, preferably amorphous or poorly crystallized and generally porous, at least one zeolite beta, whose mesh parameter is between 2,424 nm and 2,455 nm, and whose overall SiO2 / Al203 molar ratio is greater than 8, at least one element source of group VB, at least one source of group VIB element, optionally water, optionally at least one element selected from the group formed by the elements of group VIII, optionally at least one source of a member selected from the group formed by silicon, phosphorus and boron, optionally at least one source of an element selected from halogens,   that is, the elements of group VIIA.   b) maintaining said mixture at a heating temperature generally greater than about 40 C in the presence of a sulfur compound until a solid containing at least one matrix, at least one zeolite beta and at least one mixed sulphide phase.   15. Method according to one of claims 13 or 14 as one proceeds to the   sulfurization of the mixture at a temperature of 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 feeds.   17. Use according to claim 16 wherein a temperature is greater than 200 C, the pressure is greater than 0.1 MPa, the volume of hydrogen per volume of load is at least 50 liters of hydrogen per liter of charge and the hourly volume velocity is between 0.1 and 20 volume load per volume of catalyst per hour.   18. Use according to one of claims 17 such that the load is chosen in the   group consisting of gasolines, gas oils, vacuum gas oils, deasphalted residues or not, paraffinic oils, waxes and paraffins and it can   i0 contain heteroatoms such as sulfur, oxygen and nitrogen and at least one metal.