FR2778344A1 - 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 catalyst which can be used for conversion

  of hydrocarbon feedstocks, and in particular the hydrocracking of hydrocarbon feedstocks, said catalyst containing at least one hydro-dehydrogenating metal, for example, chosen from the metals of groups VIB and VIII (group 6 and groups 8, 9 and 10 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996, inside 1st cover page), at least one porous amorphous or poorly crystallized matrix (and generally of oxide type) and at least one beta zeolite . The catalyst also contains at least one promoter element deposited on the catalyst and chosen from the group formed by boron, silicon and phosphorus. In addition, the catalyst optionally contains at least one element from group VIIA (group 17 of halogens) and in particular fluorine, and optionally at least one element from group VIIB, such as

  manganese, technetium and rhenium.

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

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 catalyst according to the invention contains at least one beta zeolite at least partially in hydrogen form. By beta zeolite is meant BEA structural type zeolites as described in the work "Atlas of Zeolite Strcuture Types", W.M. Meier, D.H. Olson 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 10 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 the hydrogen form, or possibly, it has been partially exchanged with metal cations, for example cations of alkali or alkaline-earth metals and / or cations of rare earth metals of atomic number 57 to 71 inclusive (Zeolite Molecular Sieves Structure, Chemistry and Uses, DW BRECK, J. WILLEY and sons 1973). 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.

  The catalyst according to the invention has a greater hydrocracking activity and selectivity than the catalytic formulas based on beta zeolite known in the prior art. Without wishing to be bound by any theory, it seems that this particularly high activity of the catalysts of the present invention is due to the strengthening of the acidity of the catalyst by the presence of the promoter element (P. B, Si). In particular, the joint presence of boron and silicon on the matrix induces a quite interesting improvement in the properties

  in hydrocracking compared to the catalysts usually used.

  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), o10 - 0.1 to 99%, preferably from 1 to 98%, of at least one matrix amorphous or poorly crystallized porous mineral (generally of the oxide type), - 0.1 to 99.7%, advantageously from 0.1 to 90%, preferably from 0.1 to 80% and even more preferably from 0, 1 to 60% beta zeolite as defined above. the said catalyst also contains: - 0.1 to 20%, preferably 0.1 to 15% and even more preferably 0.1 to 10% of a promoter element chosen from the group formed by boron , silicon and phosphorus (the% being expressed in% oxide), and optionally, - 0 to 20%, preferably from 0.1 to 15% and even more preferably from 0.1 to 10% at least. at least one element chosen from the group VIIA (halogens), preferably fluorine - 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 VIIB group (the% being 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 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 invention may contain 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 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. 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 promoter element (P, B, Si) is deposited on the catalyst. It was introduced on the support containing at least the zeolite and the matrix, and also containing

  preferably the hydrogenating metal or metals.

  The promoter element, and in particular the silicon introduced onto the support according to the invention, 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 local contents

  in 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 in the present invention.

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

  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 hydrolyzable compounds capable of releasing 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 optionally contain at least one element of the VIIB group.

  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.

  The impregnation can be carried out in a single step by a solution containing o0 all of the constituent elements of the final catalyst, or by one or more impregnation operations, for example with excess solution on the calcined precursor. 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, for example at 500 C for 4 hours. Other impregnation sequences can be used to obtain the

  catalyst of the present invention.

  In the case where the catalyst contains an element of group VIIB deposited, 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 150 C, and finally calcined 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, and advantageously the process of as follows: c) the wet solid is left to stand under a humid atmosphere at a temperature of between 10 and 80 ° C., d) the wet solid is obtained naked in step b) at a temperature between and 150 C, e) the solid obtained in step c) is calcined at a temperature between 150 and

800 C.

  Step b) above can be carried out according to the conventional methods of a person skilled in the art. 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 process for converting hydrocarbon feedstocks with the catalyst described above and in particular the processes

  hydrocracking of hydrocarbon feedstocks.

  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.

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

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

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

between 0.01 and 5% by weight.

  The hydrocracking conditions such as temperature, pressure, hydrogen recycling rate, hourly volume speed, may be very variable depending on the nature of the feed, the quality of the desired products and the facilities available to the refiner. The temperature is generally greater than C and often between 250 C and 480 C. 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 amount 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 alumina, silica-alumina, magnesia, zirconia, titanium oxide, aluminates. 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 Vl metal (especially molybdenum or tungsten) and at least one metal or compound of group VIII metal (especially cobalt or nickel) of the classification of the elements. The total concentration of metal oxides of groups Vl 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 Vl on metal (or metals) of group VIII is between 1.25 and 20 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 430 C. 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 30001/1 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 high pressure conditions of at least 5 Mpa, preferably at least 10 Mpa, and advantageously at least 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 zeolite The support extrudates 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.

  We impregnated the sample of catalyst CZ4 with an aqueous solution containing ammonium biborate so as to deposit approximately 1.7% by mass of B2O3. 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 called CZ4B: NiMo / alumina-beta doped with boron is obtained. A catalyst CZ4Si was obtained by the same procedure as the catalyst CZ4B above but by replacing the boron precursor in the impregnation solution with the silicone emulsion Rhodorsil EP1. For this catalyst, it is sought to deposit a quantity of silicon of approximately 1.6% in

mass of SiO2.

  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 of catalyst CZ4P with an aqueous solution containing ammonium biborate so as to deposit approximately 1.7% by mass of B203. After maturation at room 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 CZ4PB NiMo / alumina-beta doped with boron is obtained. A catalyst CZ4PSi was obtained by the same procedure as the catalyst CZ4PB above but by replacing the boron precursor in the impregnation solution with the silicone emulsion Rhodorsil EP1. For this catalyst, it is sought to deposit an amount of promoter silicon of approximately 1.5% by mass of SiO2. Finally, a catalyst CZ4PBSi was obtained by the same procedure as the above catalysts but using an aqueous solution containing ammonium biborate and the silicone emulsion Rhodorsil EP1 and the same operating conditions. Fluorine is then added to this catalyst by impregnation with a dilute hydrofluoric acid solution so as to deposit approximately 1% by weight of fluorine. After drying overnight at 120 ° C. and calcination at 550 ° C. for 2 hours in dry air, the catalyst CZ4PBSiF is obtained. The final oxide contents of the CZ4 catalysts are indicated in

table 1.

  Table 1: Characteristics of CZ4 catalysts CZ4 catalyst CZ4 CZ4 0Z4 0Z4 CZ4 CZ4 0Z4 P Si B PB PSi PBSi PBSiF MoO3 (% wt) 14.2 13.6 13.9 13.9 13.4 13.4 13.2 13 , 1 NiO (% wt) 3.5 3.4 3.4 3.4 3.3 3.3 3.3 3.2 P205 (% wt) 0 4.2 0 0 4.1 4.1 4, 1 4.0 B203 (% wt) 0 0 0 1.85 1.7 0 1.7 1.6 SiO2 (% wt) 15.0 14.3 16.3 14.6 14.0 15.9 15, 2 15.1 F (% wt) 0 0 0 0 0 0 0 0.95 Addition to 10O% Addition to 100% 67.3 64.5 66.3 66.1 63.5 63.3 62.5 62, 05 consists mainly of Al203 (% wt) Zeolite beta (% wt) 15.5 14.9 15.3 15.3 14.6 14.7 14.4 14, 3 The catalyst CZ4P was then impregnated with an aqueous solution containing

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

  After maturation at room 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 the ammonium biborate and the Rhodorsil EP1 silicone emulsion (Rhone-Poulenc) so as to deposit approximately 1.9% by mass of B203 and 1.9% by mass 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 catalyst CZ4PMnBSiF is obtained. The weight contents of these catalysts are indicated

in table 2.

  Table 2: Characteristics of CZ4 catalysts containing manganese CZ4 catalyst CZ4 CZ4 PMn PMnBSi PMnBSiF MoO3 (% wt) 13.4 12.9 12.8 NiO (% wt) 3.3 3.2 3.2 MnO2 (% wt) 1.3 1.3 1.2 P205 (% wt) 4.2 4.0 4.0 B203 (% wt) 0 1.9 1.8 SiO2 (% wt) 14.1 15.3 15.1 F (% wt) 0 0 1.15 100% supplement 637 614 619 composed mainly of A1203 (% wt) Beta zeolite (% wt) 14.7 14, 2 14.0 Analysis, by electron microprobe, of the CZ4PSi catalysts , CZ4PBSi, CZ4PBSiF (table 1), and catalysts CZ4PMnBSi, CZ4PMnBSiF (table 2) 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 catalysts Hydrocracking of partially converted vacuum diesel. The catalysts, the preparations of which are described in the preceding examples, are used under the conditions of hydrocracking at moderate pressure on an oil charge, the main characteristics of which are as follows: Density (20/4) 0.921 Sulfur (% by weight) 2.46 Nitrogen (ppm weight) 1130 Simulated distillation initial point 3650C point 10% 430 0C point 50% 472 0C point 90% 504 0C end point 5390C pour point + 39 0C The catalytic test unit includes two reactors in fixed bed, at upward flow 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 a element of group VIII deposited on alumina In the second reactor, the one in which the charge passes last, a hydrocracking catalyst described above is introduced. 40 ml of catalyst are introduced. 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 Charging flow rate 40 cm3 / h

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

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

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

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

  generally at least 48 hours, has been 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 380 C.

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

  HDN hydrodenitrogenation for the four catalysts.

Table 3

  Catalytic activities of catalysts in partial hydrocracking at 400 C CB (% wt) SB (%) HDS (%) HDN (%) CZ4 NiMo / Beta 50, 0 65.0 98.95 96.1 CZ4P NiMoP / Beta 50.2 65.0 99.21 96.9 CZ4B NiMoB / Beta 50.3 65.2 99.1 96.7 CZ4Si NiMoSi / Beta 50.4 65.0 99.15 96.9 CZ4PB NiMoPB / Beta 50.4 64, 0 99.25 97.7 CZ4PSi NiMoPSi / Beta 50.4 64.5 99.35 98.4 CZ4PBSi NiMoPBSi / Beta 50.9 64.1 99.52 98.9 The results in Table 3 show that the combination of dopants B and / or Si brings an improvement in the performance of the catalyst in conversion, with a

  tolerable decrease in gross selectivity for middle distillates.

  In addition, the results in Table 3 show that it is particularly advantageous to introduce the silicon onto a precursor already containing the elements of group VIB and / or VIII and optionally at least one of the elements P. B and F. beta zeolite catalysts of the invention containing a promoter element making it possible to improve the performance of hydrocracking catalysts, and those containing phosphorus and boron and / or silicon are therefore particularly advantageous for partial hydrocracking of feedstock of vacuum distillate type containing nitrogen and in particular under pressure

moderate hydrogen.

  EXAMPLE 4 Comparison of the Hydrocracking Catalysts of a High Conversion Vacuum Azole 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 C point 50% 427 C point 90% 481 C final point 538 C This charge was obtained by hydrotreating a distillate under vacuum on an HR360 catalyst sold by the company Procatalyse comprising an element of

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

  0.6% by weight of aniline and 2% by weight of dimethyl- are then added to this charge.

  disulfide 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.

  Note 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 to middle distillate is taken equal to: SB = 100 * weight of the fraction (150 C-380 C) / weight of the fraction 380 C - of the effluent The reaction temperature is fixed so as to reach a gross conversion CB equal to 70% by weight. In the following table 4, we have reported the reaction temperature and the raw selectivity for the catalysts described above. Table 4: Catalytic activities of high conversion hydrocracking catalysts (70%)

T (C) SB (%)

  CZ4 NiMo / beta 369 51.2 CZ4P NiMoP / beta 369 51.5 CZ4PB NiMoPB / beta 367 52.1 CZ4PSi NiMoPSi / beta 367 52.4 CZ4PBSi NiMoPBSi / beta 366 53.5 CZ4PBSiF NiMoP 54 / beta 367 53.2 CZ4PMnBSi NiMoPMnBSi / beta 366 54.1 CZ4PMnBSiF NiMoPMnBSiF / beta 364 55.2 The addition of boron and / or silicon to the catalyst containing the zeolite beta and the hydro-dehydrogenating element makes it possible to improve the conversion activity, which results in a reduction in the reaction temperature necessary to reach 70% of

  conversion and provides better raw selectivity for middle distillates.

  The addition of the promoter element to the catalyst containing the beta zeolite makes it possible to improve the activity in conversion, which results in a reduction in the reaction temperature necessary to reach 70% of conversion and allows to obtain a better gross selectivity in middle distillates. In addition, if manganese is added, there is also an improvement in the converting activity with a marked improvement in the raw selectivity for middle distillates. These improvement effects are further reinforced by the presence of fluorine. Note the advantage of the phosphorus with boron and / or silicon combination. Without wishing to be linked to a particular theory, this effect is attributed to a hydrogenating function enhanced by the and the promoter elements, possibly in the presence of Mn and / or F. The catalysts according to the invention are therefore particularly advantageous for hydrocracking at high conversion. charge of the vacuum distillate type,

  especially at moderate hydrogen pressure.

Claims (17)

  1. Catalyst comprising at least one matrix, a beta zeolite, at least one hydro-dehydrogenating metal, and at least one promoter element deposited on the catalyst chosen from the group formed by boron, silicon and phosphorus. 2. Catalyst according to claim 1, further comprising at least one metal of VIIB group.   3. Catalyst according to one of the preceding claims, further comprising at minus a halogen.   4. Catalyst according to one of the preceding claims, comprising in% by weight   relative to the total mass of catalyst:   - 0.1 to 60% (expressed in% by weight of oxide) of at least one hydro-   dehydrogenating agent chosen from the group formed by the metals of groups VIB and VIII - 0.1 to 99% of at least one porous amorphous or poorly crystallized matrix, - 0.1 to 99.7% of beta zeolite, - 0.1 at 20% (expressed as% by weight of oxide) of at least one promoter element chosen from the group formed by boron, silicon and phosphorus, - 0 to 20% of at least one halogen, - 0 to 20 % (expressed as% wt of oxide) of at least one element of group VIIB.   5. Catalyst according to one of the preceding claims, in which the matrix is   chosen from the group formed by alumina, silica-alumina.   6. Catalyst according to claim 3, in which the halogen is fluorine.   7. Catalyst according to one of the preceding claims, in which the metal of group G VII B is manganese.   8. Catalyst according to one of the preceding claims in which the elements   hydro-dehydrogenating agents are chosen from nickelmolybdenum combinations,   nickel-tungsten, cobalt-molybdenum, cobalt-tungsten, nickel-cobaltmolybdenum.   9. Catalyst according to one of the preceding claims comprising boron and   silicon. 10. The catalyst according to claim 9 further comprising phosphorus.   11. Method for preparing a catalyst according to one of claims 1 to 10   in which a mixture of at least one matrix, a beta zeolite and optionally at least one hydro-dehydrogenating metal chosen from the metals of group VIII and of group VIB is prepared, said mixture is impregnated with at least one solution containing at least one promoter element chosen from boron, silicon and phosphorus.   12. The preparation method according to claim 11, in which the mixture is impregnated with at least one solution of at least one element from group VIIA, before, after or simultaneously with the impregnation with the solution of the promoter element.   13. Preparation process according to one of claims 1 1 or 12 in which   impregnates the mixture 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 14. The preparation method according to claim 11 wherein the mixture   also contains the element (s) of group VIIB.   15. Preparation process according to one of claims 11 to 14, in which the   mixture also contains phosphorus and is impregnated with at least one   solution containing boron and by at least one solution containing silicon.   16. Process for the conversion of hydrocarbons with a catalyst according to one   of claims there 10 or with a catalyst prepared according to one of claims 11 to 15.   17. The method of claim 16 for hydrocracking.