FR2778410A1 - Catalyst comprising beta zeolite and promoter element for hydrocracking - Google Patents

Abstract

The catalyst has an activity and selectivity in hydrocracking greater than previous formulations based on a beta zeolite due to the presence of a promoter element in the matrix, chosen from boron (B), silicon (Si) and phosphorus (P). The catalyst comprises a matrix, a beta zeolite, a hydro-dehydrogenating metal and a promoter element deposited in the matrix of the catalyst, comprising boron, silicon or phosphorus. Independent claims are also included for the preparation of the catalyst and its use in a hydrocracking process.

Description

The present invention relates to a hydrocracking process with a

catalyst to

beta zeolite base.

  The treated hydrocarbon feedstocks, such as petroleum cuts and cuts derived from coal, contain aromatic, and / or olefinic, and / or naphthenic, and / or paraffinic compounds, and optionally metals, and / or nitrogen,

  and / or oxygen and / or sulfur.

  Hydrocracking is becoming more and more important in the practice of refining with the increasing need to convert heavy fractions into lighter fractions which can be recovered as fuels. This results from the growing demand for fuels. This recovery involves a relatively significant reduction in the molecular weight of the heavy constituents, which can be obtained by

  example by means of cracking reactions.

  The catalytic hydrocracking process uses catalysts containing on the one hand a hydrogenating, desulfurizing and denitrogenating function provided by the active phase based on transition metals and on the other hand an acidic function,

  general provided by the amorphous matrix or a zeolite or their mixture.

  A good hydrocracking catalyst will consist of a well adjusted hydrogenating function and an acid function. Hydrocracking is used to treat fillers such as vacuum gas oils, atmospheric residues or vacuum, deasphalted or not. Hydrocracking allows for lighter cuts

  highly purified, ie low in sulfur, nitrogen and metals.

  It is therefore important to increase the activity and selectivity of the hydrocracking catalysts. One way is to acidify the matrix without poisoning the activity of the hydrogenation phase based on transition metals or the activity

  crispy zeolite-based acid phase.

  ) The present invention relates more precisely to a process for hydrocracking

  hydrocarbon feedstocks, said catalyst containing at least one hydro-

  dehydrogenating agent, for example chosen from group VIB and group VIII (group 6 and groups 8, 9 and 10 according to the new notation of the periodic classification of elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996, inside 1st page of cover), at least one matrix which may be an amorphous or poorly crystallized porous matrix (and generally of the oxide type) at least one zeolite

  beta, and at least one element of the VIIB group.

  The catalyst according to the invention contains at least one beta zeolite at least partially in hydrogen form. By beta zeolite is meant a BEA structural type zeolite described in

  the book "Atlas of Zeolite Structure Types", W.M. Meier, D.H. Oison and Ch.

  Baerlocher, 4th Revised edition, 1996, Elsevier.

  Among the beta zeolites, it is usually preferred to use beta zeolites whose overall atomic ratio, silicon / aluminum (Si / AI) is greater than approximately 10 and more preferably beta zeolites whose Si / AI ratio is between and 200 and even more preferably between 10 and 150. These beta zeolites having the Si / AI ratios described above can be obtained in synthesis or

  by any post-synthesis dealumination technique known to those skilled in the art.

  Beta zeolites are advantageously used either entirely in hydrogen form or in at least 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 included. The cation / AI atomic ratio is less than 0.8, preferably less than 0.5 and even more preferably less than 0.1. The preferred beta zeolites according to the invention have BET surfaces greater than 400 m2 / g and preferably

  between approximately 450 and 850 m2 / g.

  Said catalyst has a greater hydrocracking activity and selectivity than the catalytic formulas based on beta zeolite known in the prior art. The catalyst of the present invention generally contains in% by weight relative to the total mass of the catalyst: - 0.1 to 60%, preferably from 0.1 to 50% and even more preferably from 0.1 to 40% at least one hydro-dehydrogenating metal chosen from group VIB and group VIII (the% being expressed as% oxide), - 0.1 to 99%, preferably from 1 to 98%, of at least one porous matrix amorphous or poorly crystallized generally of the oxide type, - 0.1 to 99.79%, advantageously from 0.1 to 90%, preferably from 0.1 to 80% and even more preferably from 0.1 to 60% at least one beta zeolite as defined above. - 0.1 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to 10% of at least one element chosen from the group VIIB (expressed as% oxide). and optionally, - 0 to 20%, preferably from 0.1 to 15% and even more preferably from 0.1 to 10% of at least one element chosen from the group VIIA, preferably fluorine 0 to 20 %, preferably from 0.1 to 20%, advantageously from 0.1 to 15% and even more preferably from 0.1 to 10% of at least one element chosen from the

  group formed by boron, silicon and phosphorus (expressed in% oxide).

  The metals of group VIB, group VIII and group VIIB of the catalyst of the present invention may be present in whole or in part in the form

  metallic and / or oxide and / or sulfide.

  The catalyst of the invention contains at least one element of the VIIB group such as

  manganese, technetium, rhenium; manganese and rhenium being preferred.

  The sources of the VIIB group element which can be used are well known to those skilled in the art. Ammonium salts, nitrates and

chlorides.

  The element of group VIIB has preferably been deposited on the catalyst

  advantageously by impregnation with a solution of this element.

  The hydrogenating function is provided by at least one element from groups VIB or

  VIII. Among the elements of group VIB, molybdenum and tungsten are preferred.

  The sources of the VIB group element 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. The oxides and ammonium salts such as ammonium molybdate, ammonium heptamolybdate and ammonium tungstate are preferably used. The catalyst of the present invention may contain a group VIII metal such as iron, ruthenium. , rhodium, palladium, osmium, iridium, platinum and preferably cobalt, nickel. Advantageously, the following combinations of metals are used:

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

  tungsten, cobalt-tungsten, the preferred combinations are: nickelmolybdenum, nickel-tungsten. It is also possible to use associations of three metals

  for example nickel-cobalt-molybdenum.

  The sources of Group VIII elements which can be used are well known to those skilled in the art. For example, nitrates, sulfates, phosphates, halides for example, chlorides, bromides and fluorides,

  carboxylates, for example acetates and carbonates.

  The catalyst of the present invention therefore also contains at least one

  porous amorphous or poorly crystallized mineral matrix generally of the oxide type.

  Mention may be made, by way of nonlimiting example, of aluminas, silicas, silica-

  aluminas. We can also choose aluminates or boron oxide, phosphates (aluminum phosphate for example). It is preferred to use matrices containing alumina, in all of these forms known to those skilled in the art, and

  even more preferably aluminas, for example gamma alumina.

  It is also advantageous to use mixtures of alumina and silica,

  mixtures of alumina and silica-alumina.

  The optional promoter element (P, B, Si) is preferably deposited on the catalyst.

  It was introduced on the support containing at least the zeolite and the matrix, and

  preferably also containing the hydrogenating metal or metals.

  The promoter element deposited, and in particular the silicon introduced onto the support according to the methods described below, is mainly located on the matrix of the support and can be characterized by techniques such as the Castaing microprobe (distribution profile of the various elements), transmission electron microscopy coupled with an X-analysis of the components of the catalysts, or even by establishing a distribution map of the elements present in the catalyst by electron microprobe. These local analyzes will provide the location of the various elements, in particular the location of the promoter element, in particular of the amorphous silica on the matrix of the support due to the introduction of the promoter silicon according to the invention. The location of the silicon of the framework of the zeolite contained in the support is also revealed. In addition, a quantitative estimate of the local contents of silicon or other promoter elements may be

performed.

  On the other hand, the NMR of the solid of 29Si rotating at the magic angle is a technique which makes it possible to detect the presence of amorphous silica introduced into the catalyst.

according to the procedure described.

  The promoter element may, in another embodiment, be introduced into the structure of the beta zeolite by cation exchange, preferably carried out before the zeolite is mixed with the matrix. In this case, boron and phosphorus are the

preferred promoter elements.

  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 a boric acid solution

in a water / alcohol mixture.

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

pyrrole family.

  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.

  Many sources of silicon can be used. Thus, ethyl orthosilicate Si (OEt) 4, siloxanes, polysiloxanes, silicones, silicone emulsions, halide silicates such as ammonium fluorosilicate (NH4) 2 SiF6 or fluorosilicate can be used. 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 be added for example by impregnating a silicone emulsion in water.

  l5 The catalyst of the invention may also contain at least one halogen, fluorine

being preferred.

  The sources of elements of group VIIA 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.

  The promoter element and optionally the element chosen from group VIIA of halides, can be introduced by impregnation into the catalyst at various

  levels of preparation and in various ways.

  In general, a mixture is prepared containing at least one matrix, beta zeolite, and optionally at least one hydrogenating metal chosen from

  Group VIII and Group VIB metals. The mixture is or is not shaped.

  It can possibly contain (but not preferred) at least one element of the group VIIB. The impregnation of the mixture (with at least one solution containing at least one promoter element and optionally the halogen) 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 a single step by a solution containing all of the constituent elements of the final catalyst, or by one or more impregnation operations, for example with excess solution on the precursor

calcined.

  In the case where the catalyst contains boron, a preferred method according to the invention consists in preparing an aqueous solution of at least one boron salt such as ammonium biborate or ammonium pentaborate in an alkaline medium and in the presence of hydrogen peroxide and to carry out a so-called dry impregnation, in which one fills

  the pore volume of the precursor by the boron-containing solution.

  In the case where the catalyst contains silicon, preferably a

  solution of a silicon compound of the silicone type.

  In the case where the catalyst contains boron and silicon, the deposition of boron and silicon can also be carried out simultaneously using a solution containing a boron salt and a silicon compound of the silicone type. So for example (and

  in the preferred case o for example the precursor is a nickel-type catalyst

  molybdenum supported on a support containing zeolite and alumina) it is possible to impregnate this precursor with aqueous solution of ammonium biborate and silicone Rhodorsil El P from the company Rhône Poulenc, to carry out a drying for example at 80 ° C., then to impregnate with an ammonium fluoride solution, to carry out a drying for example at 80 ° C., and to carry out a calcination for example and preferably in air in a crossed bed, for example at

500 C for 4 hours.

  In the case where the catalyst contains at least one element of group VIIA, the mixture is impregnated with at least one solution of at least one element of group VIIA, before, after or simultaneously with the impregnation with the solution of the element promoter. It is for example possible to impregnate the catalyst with an ammonium fluoride solution, to carry out a drying for example at 80 ° C., and to carry out a calcination for example and preferably in air in a crossed bed, by

example at 500 0C for 4 hours.

  Other impregnation sequences can be used to obtain the

  catalyst of the present invention.

  To deposit at least one element of group VIIB on the catalyst, the mixture is impregnated with at least one solution of at least one element of group VIIB, before,

  after or simultaneously with the impregnation with the solution of the promoter element.

  In the case where the metals are introduced in several impregnations of the corresponding precursor salts, an intermediate drying step of the catalyst is generally carried out at a temperature generally between 60 and 250 ° C. and advantageously an intermediate calcination step of the catalyst is generally carried out at a temperature between 150 and 800 C,

generally between 250 and 600 C.

  Generally, in order to complete the preparation of the catalyst, the wet solid is left to stand under a humid atmosphere at a temperature between 10 and C, then the wet solid obtained is dried at a temperature between 60 and C, and finally the solid obtained at a temperature between 150 and

  8000C, generally between 250 and 600 C.

  A preferred catalyst of the invention contains boron and silicon, and advantageously it also contains phosphorus. Preferably, it also contains nickel and molybdenum or cobalt and molybdenum, or nickel and

tungsten.

  Preferably, a NiMo or NiMoP catalyst on a support comprising a mixture of alumina and beta zeolite is impregnated with an aqueous solution of boron then an aqueous solution of silicon (or the reverse solution of silicon then of

  boron) or is impregnated with a common aqueous solution of boron and silicon.

  Thus, it is possible to first impregnate the solution containing the silicon, to dry, to calcine and to impregnate the solution containing the boron of

  dry and proceed to final calcination.

  It is also possible to first impregnate the solution containing the boron, to dry, to calcine and to impregnate the solution containing the silicon of

  dry and proceed to final calcination.

  It is also possible to first impregnate the precursor with a solution containing phosphorus, to dry, to calcine and then to impregnate the solid obtained with the solution containing boron, to dry, to calcine and to impregnate the

  solution containing silicon to dry and proceed to final calcination.

  More particularly, the process for the preparation of the catalyst of the present invention comprises the following stages: a) a mixture hereinafter called the precursor is prepared, containing at least the following compounds: at least one porous amorphous or poorly crystallized matrix, at least one beta zeolite of structural type BEA, at least one element from group VIB, and optionally at least one element from group VIII, optionally at least one element from group VIIB, optionally phosphorus, the whole being preferably shaped and dried, b) the precursor defined in step a) is impregnated with an aqueous solution containing boron and / or silicon, optionally phosphorus and optionally at least one element of group VIIA, b ') the defined precursor is impregnated in step a) or in step b) with an aqueous solution of at least one element of group VIIB if this element has not been completely introduced during step a), e t advantageously the process is terminated in the following manner: c) the wet solid is allowed to stand under a humid atmosphere at a temperature between 10 and 80 ° C., d) the wet solid obtained in step b) is dried at a temperature between and 1500C, e) the solid obtained in step c) is calcined at a temperature between 150 and

800 C.

  Step b) and step b ') above can be carried out according to the methods

classics of the skilled person.

  Step b) requires having an aqueous solution containing boron and / or silicon and therefore is different from the conventional methods for depositing B and / or Si known to those skilled in the art. A preferred method according to the invention consists in preparing an aqueous solution of at least one boron salt such as ammonium biborate or ammonium pentaborate in an alkaline medium and in the presence of hydrogen peroxide and to introduce into the solution a silicon type silicon compound and to carry out a so-called dry impregnation, in which the pore volume of the precursor is filled with the solution containing B and Si. This method of depositing B and Si is better than the conventional method employing a solution

  alcoholic boric acid or a solution of ethyl orthosilicate in alcohol.

  The catalysts obtained by the present invention are shaped in the form of grains of different shapes 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 50 and 600 m2 / g , a pore volume measured by mercury porosimetry of between 0.2 and 1.5 cm3 / g and a pore size distribution which can

  be monomodal, bimodal or polymodal.

  The invention also relates to a hydrocracking process with catalysts

described above.

  The catalysts obtained by the present invention can be used for the hydrocracking of hydrocarbon feedstocks such as petroleum fractions. The fillers used in the process are for example 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 cracking processes (without hydrogen) or catalytic cracking in a fluidized bed (FCC) and their mixtures. They contain heteroatoms such as sulfur, oxygen and nitrogen and

possibly metals.

  1o The catalysts thus obtained are advantageously used for hydrocracking in particular heavy hydrocarbon cuts of the distillate type under vacuum, 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 higher than 2000C and often between 250 0C and 4800C. The pressure is greater than 0.1 MPa and often greater than 1 MPa. The hydrogen recycling rate is at least 50 and often between 80 and 5000 normal liters of hydrogen per liter of charge. The hourly space velocity is generally between 0.1 and 20

  volume of charge per volume of catalyst and per hour.

  The catalysts of the present invention are preferably subjected to a sulphurization treatment making it possible to transform, at least in part, the metallic species into sulphide before they are brought into contact with the charge to be treated. This activation treatment by sulfurization is well known to those skilled in the art and can

  be performed by any method already described in the literature.

  A conventional sulfurization method well known to a person 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 an area

reaction with crossed bed.

  The catalyst of the present invention can be advantageously used for the hydrocracking of sections of the distillate type under vacuum highly charged with sulfur and nitrogen. 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. and preferably at 300 ° C., generally at most 480 ° C., and often between 350 ° C. and 450 ° C. The pressure is generally greater than 2MPa and

  preferably 3MPa, it is less than 12MPa and preferably less than 10MPa.

  The quantity of hydrogen is at least 100 normal liters of hydrogen per liter of charge and often between 200 and 3000 normal liters of hydrogen per liter

  dump. The hourly space velocity is generally between 0, 1 and 10h-1.

  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 chosen from the group formed by magnesia, zirconia, titanium oxide, aluminates, alumina, silica, silica-alumina. The hydrotreatment function is provided by at least one

  metal or group VIII metal compound such as nickel and cobalt in particular.

  It is possible to use a combination of at least one metal or compound of group VI metal (in particular molybdenum or tungsten) and of at least one metal or compound of group VIII metal (especially cobalt or nickel) of the periodic classification of the elements. The total concentration of metal oxides of groups VI and VIII is between 5 and 40% by weight and preferably between 7 and 30% by weight and the weight ratio expressed as metal oxide in metal (or metals) of group VI on metal ( or metals) of group VIII is between 1.25 and

  and preferably between 2 and 10. In addition, this catalyst may contain phosphorus.

  The phosphorus content, expressed as a concentration of diphosphorus pentoxide P205, will generally be at most 15%, preferably between 0.1 and 15% by weight and preferably between 0.15 and 10% by weight. It can also contain boron in a ratio B / P = 1.05 - 2 (atomic), the sum of the contents in

  B and P expressed as oxides being 5-15% by weight.

  The first step generally takes place at a temperature of 350-460 C, preferably 360-450 C, a total pressure of at least 2MPa; and preferably 3 MPa, an hourly volume speed of 0.1-5h-1 and preferably 0.2-2h-1 and with a quantity of hydrogen of at least 100NI / NI of charge, and preferably 260-3000NI / OR

dump.

  In this second embodiment, 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 4300C. The pressure is generally at least 2MPa and preferably 3MPa, it is less than 12MPa and preferably less than 10MPa. The quantity of hydrogen is at least 1001 / I of charge and often between 200 and 30001 / I of hydrogen per liter of charge. The hourly space velocity is generally between 0.15 and 10h-1. Under these conditions, the catalysts of the present invention exhibit better activity in conversion, in hydrodesulfurization, in hydrodenitrogenation and better selectivity in middle distillates than the commercial catalysts. The service life of

  catalysts is also improved in the moderate pressure range.

  In another embodiment, the catalyst of the present invention can be used for hydrocracking under conditions of high hydrogen pressure of at least 5 Mpa, preferably at least 10 Mpa, and advantageously at least minus 12 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 or equal to 55%. In this case, the petroleum cut conversion process takes place in two stages, the

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

  The catalyst of the first stage is identical to that described above and used under the conditions described, the pressure being adjusted to that of this other mode

of achievement.

  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 430 C. The quantity of hydrogen is at least 1001 / I

  of charge and often between 200 and 30001 / I of hydrogen per liter of charge.

  The hourly space velocity is generally between 0.15 and 10h-1.

  Under these conditions, the catalysts of the present invention exhibit better conversion activity and better selectivity for middle distillates than commercial catalysts, even for considerably zeolite contents.

  lower than those of commercial catalysts.

  The following examples illustrate the present invention without, however, limiting its scope. EXAMPLE 1 Preparation of a Support Containing a Beta Zeolite A hydrocracking catalyst support containing a beta zeolite was manufactured in large quantities so as to be able to prepare different catalysts based on the same support. For this, use is made of 18.9% by weight of a beta zeolite having an overall Si / AI ratio (measured by X-ray fluorescence) of 23.1, an atomic ratio measured by atomic adsorption of Na / AI = 0.003, a BET surface 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 a matrix composed of ultrafine tabular boehmite or alumina gel marketed 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 15 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 in humid air containing 7.5% volume of water.

  One thus obtains cylindrical extrudates of 1.2 mm in diameter, having a specific surface of 286 m2 / g, a pore volume of 0.39 cm3 / g and a size distribution of monomodal pore centered on 11 nm. Analysis of the matrix by X-ray diffraction reveals that it is composed of low cubic gamma alumina

  beta crystallinity and zeolite.

  EXAMPLE 2 Preparation of Hydrocracking Catalysts Containing a beta 1 zeolite The extrudates of support containing a beta zeolite of 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 and finally calcined in air at 550 C.

  The oxide contents by weight of the catalyst CZ4 obtained are indicated in

table 1.

  The support extrudates containing a beta zeolite from Example 1 are impregnated to dryness with an aqueous solution of a mixture of ammonium heptamolybdate, nickel nitrate and orthophosphoric acid, dried overnight at 120 ° C. in air. and

  finally calcined in air at 550 C. The catalyst CZ4P is thus obtained.

  We impregnated the sample CZ4 of Example 1 with an aqueous solution of ammonium perrhenate NH4ReO4 so as to deposit approximately 1% of ReO3. We

thus obtains the catalyst C24Re.

  The CZ4P catalyst was then impregnated with an aqueous solution containing

  manganese nitrate so as to deposit approximately 1.4% by mass of MnO2.

  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 in dry air. A catalyst named CZ4PMn is obtained. This catalyst is then impregnated with an aqueous solution containing ammonium biborate and the Rhodorsil EP1 silicone emulsion (Rhone-Poulenc) so as to deposit approximately 1.9% by weight of B203 and 1.9% by weight of SiO2. The impregnated extrudates are then dried overnight at 120 ° C. and then calcined at 550 ° C. for 2 hours in dry air and the catalyst CZ4PMnBSi is obtained. Fluorine is then added to this catalyst by impregnation with a dilute hydrofluoric acid solution so as to deposit approximately 1% by mass of fluorine. After drying overnight at 120 ° C. and calcination at 550 ° C. for 2 hours in dry air, the

CZ4PMnBSiF catalyst.

  The weight contents of these catalysts are indicated in Table 1. Table 1: Characteristics of the catalysts Catalyst CZ4 CZ4 CZ4 CZ4 CZ4 CZ4 P Re PMn PMn PMn BSi BSiF MoO3 (% wt) 14.2 13.6 13.9 13.4 12.9 12.8 NiO (% wt) 3.5 3.4 3.4 3.3 3.2 3.2 P2o05 (% wt) 0 4.2 0 4.2 4.0 4.0 MnO2 ( wt%) 0 0 0 1.3 1.3 1.2 B203 (wt%) 0 0 0 0 1.9 1.8 SiO2 (wt%) 15.0 14.3 14.6 14.1 15.3 15.1 F (% wt) 0 0 0 0 O 1.15 o ReO3 (% wt) 0 0 2.05 0 0 0 Complement at 100% 67.3 64.5 66.00 63.7 61.4 61 , 9 composed mainly of Al203 (% wt) l0 Analysis, by electron microprobe, of CZ4PMnBSi, CZ4PMnBSiF shows that the silicon added to the catalyst according to the invention is mainly located on the matrix and is in the form of amorphous silica Example 3 : Comparison of hydrocraqua.qe catalysts of a vacuum gqazole

a partial conversion.

  The catalysts, the preparations of which have been described above, are used under the conditions of hydrocracking at moderate pressure on an oil charge, the main characteristics of which are as follows Density (20/4) 0.921 Sulfur (% by weight) 2.46 Nitrogen (ppm) weight) 1130 Simulated distillation initial point 3650C point 10% 4300C point 50% 4720C point 90% 504 0C end point 5390C pour point + 39 C The catalytic test unit includes two reactors in a fixed bed, with upward circulation of the charge (“up-flow”). In the first reactor, that in which the charge passes first, the catalyst of first hydrotreatment stage HTH548 sold by the company Procatalyse is introduced, comprising an element from group Vl and an element from group VIII deposited On alumina. In the second reactor, the one in which the charge passes last, a hydrocracking catalyst described above is introduced. In each of the reactors, there is introduced oduit 40 ml of catalyst 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 Hydrotreating catalyst 40 cm3 Hydrocracking catalyst 40 cm3 Temperature 400 C Hydrogen flow rate 20 I / h Charge flow rate 40 cm3 / h The catalysts undergo an in-situ sulfurization step before reaction. Note that any in-situ or exsitu 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 4000C (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 respected.

  The gross conversion CB is taken equal to: CB =% by weight of 380 C of the effluent The fraction 380 C of the effluent signifying the part of the effluent boiling at

below 308 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 380 C of the effluent The conversion to hydrodesulfurization HDS is taken equal to: HDS = ( Sinitial - Seffîuent) / 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 Table 2, we have reported the gross conversion CB to 400 C, the gross selectivity SB, the conversion to hydrodesulfurization HDS and the conversion to

  HDN hydrodenitrogenation for catalysts.

Table 2

  Catalytic activities of catalysts in partial hydrocracking at 400 C rI | CB (% wt) SB (%) HDS (%) HDN (%) CZ4 NiMo / Beta 50.0 65.0 98.95 96.1 CZ4Re 50.5 65.5 99.40 98.2 The results in the table show that the presence of G VIIB brings a

  improvement of catalyst performance in conversion and refining.

  Example 4 Comparison of the 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 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 OC point 50% 427 C point 90% 481 C end 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 Vl and an element of group VIII deposited on alumina.

  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 Catalytic performance is expressed by the temperature which allows to reach a gross conversion level of 70% and by the gross selectivity to distillates at 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 C 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 0C of the effluent The reaction temperature is fixed so as to achieve a conversion

gross CB equal to 70% by weight.

  Table 3: Catalytic activities of catalysts in high hydrocracking 1 0 conversion (70%)

__T (C) SB (%)

  CZ4 NiMo / beta 369 51.2 CZ4P NiMoP / beta 369 51.5 CZ4PBSi NiMoPBSi / beta 366 53.5 CZ4PBSiF NiMoPBSiF / beta 365 54.8 CZ4PMn NiMoPMn / beta 367 53.2 CZ4PMnBiNiBi.1 / beta 364 55.2 If manganese is added, there is an improvement in the converting activity with a marked improvement in the raw selectivity for middle distillates. This effect is attributed to a hydrogenating function exalted by Mn or Re in the previous example.

Claims (11)

  1. Process for hydrocracking hydrocarbon feedstocks with a catalyst containing at least one matrix, at least one beta zeolite, at least one hydro-dehydrogenating element and at least one element from group VIIB. 2. Method according to claim 1, in which the matrix is chosen from the   group formed by alumina, silica, silica-alumina, aluminates.   0 3. Method according to one of the preceding claims, in which the beta zeolite   contains in its structure at least one promoter element chosen from boron or phosphorus.   4. The method of claim 3, wherein the promoter element was introduced into the beta zeolite, before mixing with the matrix, by cation exchange.   5. Method according to one of claims 1 or 2, wherein at least one element   promoter chosen from boron, phosphorus, silicon has been deposited on the catalyst.   6. Method according to one of the preceding claims, wherein the element   hydrogenating agent is chosen from the metals of groups VI B and VIII.   7. Method according to one of the preceding claims, wherein the element of   group VII B is deposited on the catalyst.   8. Method according to one of the preceding claims, operating at at least 200 C   under a pressure higher than 0.1 MPa, with a hydrogen recycling rate   at least 50 and an hourly volume speed of 0.1-20 h'1.   9. Method according to one of the preceding claims operating at a temperature   at least 230 C, under a pressure of more than 2 MPa and less than 12 Mpa, with an hourly volume speed of 0.1-10 h-'1 and a quantity of hydrogen of at least 100 NI / I load, and so that the conversion level is less than 55%.   10. Method according to one of claims 1 to 8 operating at a temperature of at least   minus 230 C, a pressure of at least 5 Mpa, the hourly volume speed of 0.15 - 10 h 'and the quantity of hydrogen of at least 100 1 / I of charge, and so as to   that the conversion level is greater than or equal to 55%.   11. Method according to one of the preceding claims operating on a load   hydrocarbon chosen from gasolines, kerosene, gas oils, gas oils under vacuum, atmospheric residues, vacuum residues, atmospheric distillates, vacuum distillates, heavy fuels, oils, waxes,   paraffins, used oils, deasphalted residues, deasphalted crudes.