MXPA98010790A - Catalyst contains a zeolite euo and its use in isomerization of compounds c8 aromati - Google Patents

Abstract

The present invention relates to a catalyst comprising at least one zeolite of structural type EUO, for example, the zeolite EU-1, at least partly under formazide, at least one matrix, at least one metal of group VIII of the classification periodically of the elements, said zeolite comprising silicon and at least one element T selected from the group consisting of aluminum, iron, gallium and boron, (preferably aluminum and boron), with a global atomic ratio Si / T greater than 5, the aforementioned catalyst being characterized in that the dispersion of said group VIII metal is comprised between 50% and 100% including limits, and the macroscopic distribution coefficient of said group VIII metal is comprised between 0.7 and 1.3 limits including, the catalyst having such mechanical strength that the value of the crush in bed is greater than 0.7 MPa. The invention also concerns the preparation of a catalyst as well as its use in a process of isomerization of aromatic C8 compounds

Description

CATALYST CONTAINS A ZEOLITE EÜO AND ITS USE IN ISOMERIZATION OF COMPOUNDS C8 AROM TICOS.

The invention concerns a catalyst containing at least one zeolite of structural type EUO, for example the zeolite EU-1, at least partly in acid form, at least one matrix (linker), at least one element of group VIII of the classification periodical of the elements, Handbook of Physics and Chemistry, 76th edition, possibly at least one metal belonging to the group formed by groups IIIA and IVA of the periodic classification of the elements, possibly sulfur, the aforementioned zeolite comprising silicon and at least one element T selected from the group consisting of aluminum, iron, gallium and boron, preferably aluminum and boron, with the global atomic ratio Si / T greater than 5, preferably between 5 and 100 limits included, said metal of group VIII which is preferably deposited on the matrix, well dispersed on the surface of the catalyst and well distributed macroscopically through the grain of the catalyst. Furthermore, this transformed catalyst, for example in the form of beads or extrudate, has a good mechanical resistance. REF. 29080 The invention also concerns the use of the catalyst in an isomerization process of the aromatic compounds of 8 carbon atoms.

The isomerization of xylenes of etibenzene requires the presence of a group VIII metal. The optimized formulations based on mordenite and a metal of group VIII leads to catalysts with which the parasitic reactions remain non-negligible. For example, the opening of naphthenic cycles followed or not by fractionation or even the dismutation and transalkylation reactions of the C8 aromatics leading to the formation of uninvestigated aromatics can be mentioned. It is then particularly interesting to find new more selective catalysts.

Among the zeolites used in isomerization of aromatic C8 cuts, is the ZSM-5. alone or in mixture with other zeolites such as mordenite for example. These catalysts are particularly described in patents USP-4467129, USP-4482773 and EP-B-138617. Other catalysts are based on mordenite and have been described for example in patents USP-4723051, USP-4665258 and FR-A-2477903.

The lack of selectivity of the mordenite can be attenuated by an optimization of the formulations and / or of the specific treatments such as that which has, for example, been described in patent FR-2,691,914 of the applicant. These techniques allow to diminish the parasitic reactions of dismutation.

The EU-1 zeolite of structural type EUO, already described in the previous specialty, has a microporous one-dimensional system, whose pore diameter is 4.1 X 5 A ° (1 A ° = 1 Angstrón = l / lOio m) ("Atlas of Zeolite Structure Types ", WM Meier and DH Olson, Fourth Edition, 1996). In addition, N. A. Briscoe et al. Have shown in an article in the journal Zeolitas (1988, 8, 74) that these one-dimensional channels have lateral bags of depth of 8.1 A ° and diameter 6.8 X 5.8 A °. The mode of synthesis of the EU-1 zeolite and its physico-chemical characteristics have been described in patent EP-B1-42 226. U.S. -4 640 829 concerns, zeolite ZSM-50, which, according to the "Atlas of Zeolite Structure Types", W. M. Meier and d. H. Olson, 4a. Edition, 1996, presents the same EUO structural type as the EU-1 zeolite. The aforementioned patent presents a manner of synthesis of the ZSM-50 different from that described in the patent EP-B1-42 226 on the zeolite EU-1. The patent application EP-A1-51 318 deals with the zeolite TPZ-3, which presents, according to the "Atlas of Zeolite Structure Types", W. M. Meier and D. H. Olson, 4th. Edition, 1996, the same EUO structural type as the EU-1 zeolite, and its use as a catalyst containing the zeolite as such or transformed. In the mentioned document the transformation of zeolite TPZ-3 is exemplified by the preparation of tablets, obtained by tabletting a mechanical mixture of zeolite powders and binders. The tablets contain the zeolite TPZ-3, a linker and optionally at least one element selected from the group consisting of iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, rhenium, osmium, iridium, and platinum, in the form of metal or metal oxide.

Surprisingly, a transformed catalyst has been discovered by the applicant, which contains: - at least one zeolite of structural type EUO, for example the zeolite EU-1, at least in part and preferably almost entirely in the acid form, containing silicon and at least one element T selected from the group consisting of aluminum, iron, gallium, and boron, preferably aluminum and boron, and such, that the global atomic ratio Si / T is greater than 5, preferably between approximately 5 and 100 included limits. at least one matrix (linker), for example alumina. - at least one element of group VIII of the priodic classification of the elements, possibly at least one metal belonging to the group formed by groups IIIA and IVA of the periodic classification of the elements, - and eventually sulfur, the catalyst mentioned which is characterized in that: - the dispersion of the group VIII metals, determined by chemisorption, for example by titration H2-02 or carbon monoxide chemisorption, is between 50% and 100%, including limits, preferably between 60% and 100%. % limits included, and even more preferred between 70% and 100% limits included, - the macroscopic distribution coefficient of the aforementioned metal (s), obtained from its profile determined by a Castaing microprobe, defines how the The concentration ratio of said metal to the core of the grain in relation to the edge of the same grain, is comprised between 0.7 and 1.3 included limits, preferably between 0.8 and 1.2 included limits. - the crushing value in bed, determined according to the Shell method (SMS 1471-74) is higher than 0.7 MPa.

The catalyst leads to excellent catalytic results in hydrocarbon transformations such as, for example, the isomerization reactions of the C8 aromatic Cs cut, ie mixtures consisting of xylenes and optionally ethylbenzene.

The matrix (binder) consists more particularly in at least one element selected from the group consisting of natural clays (such as kaolin or bentonite), synthetic clays, magnesia, aluminas, silicas, silica-aluminas. , titanium oxide, boron oxide, zirconium, aluminum phosphates, titanium phosphates, zirconium phosphates, preferably between the elements of the group consisting of aluminas and clays.

The structural zeolite EUO, for example the zeolite EI-1, contained in the catalyst according to the invention, is at least partially, preferably almost completely, in the acid form, ie in the hydrogen form (H *), the content of sodium being preferably such that the general atomic ratio Na / T is less than 0.5, preferably less than 0.1, still more preferably less than 0.02.

The catalyst according to the invention contains more particularly: - a weight content, from 1 to 90% including limits, and preferably from 3 to 60% inclusive limits, and even more preferably from 4 to 40% inclusive limits of at least one EUO structural type zeolite, for example the zeolite EU-1, at least partly in acid form, comprising silicon and at least one element T selected from the group consisting of aluminum, iron, gallium and boron, preferably aluminum and boron, the ratio global atomic Si / T is greater than 5, preferably comprised between 5 and 100 included limits, even more preferably between 5 and 80 included limits, at least one element of group VIII of the periodic classification of the elements, preferably selected from the group consisting of platinum and palladium, even more preferably platinum. The weight content of the aforementioned elements (s) is generally comprised between 0.01 and 2.0% limits included, preferably between 0.05 and 1.0% limits included. The dispersion of the mentioned element (s) of group VIII, determined by chemisorption, is comprised between 50% and 100% limits included, preferably between 60% and 100% limits included, and even more preferably between 70% and 100% limits included. The macroscopic distribution coefficient of the aforementioned element (s) of group VIII, calculated from its profile determined by Castaing microprobe, the aforementioned coefficient which is defined as the ratio of the concentrations of the ) mentioned element (s) of group VIII in the heart of the grain in relation to the edge of this same grain, is comprised between 0.7 and 1.3 included limits, and preferably between 0.8 and 1.2 included limits, optionally at least one additional element selected in the set formed by the groups IHA and IVA of the periodic classification of the elements, preferably selected in the group formed by the Indian and the tin. The weight content of the aforementioned item (s) is generally comprised between 0.01 and 2.0% including limits, preferably between 0.05 and 1.0% limits included. - possibly sulfur, whose content is such that the ratio of the number of sulfur atoms to the number of metal atoms of group VIII deposited, is comprised between 0.5 and 2 included limits, - at least one matrix, or linker, which ensures the 100% complement in the catalyst.

Said catalyst is further characterized in that the bed crush value, determined according to the Shell method (SMS 1471-74) and which characterizes its mechanical strength, is greater than 0.7 MPa.

The deposit of at least one element of group VIII is operated in such a way that the dispersion of the aforementioned element (s), determined by chemisorption is between 50% and 100% inclusive limits, preferably between 60 and 100%. % and 100% limits included, and even more preferred between 70% and 100% limits included. In the case where the introduction of at least one element of group VIII of the priodic classification of the elements and possibly of at least one element belonging to the groups IIIA and IVA is effected after the zeolite of structural type EUO, for example the zeolite EU-1, has been transformed, for example in the form of beads or extrudates, it is important to obtain a good distribution of the aforementioned element (s) in the transformed catalyst. This distribution is characterized by its profile obtained by Casting microprobe. The ratio of the concentrations of each element of group VIII in the heart of the grain in relation to the edge of this same grain, defined as being the distribution coefficient, should be between 0.7 and 1.3 included limits, preferably between 0.8 and 1.2 limits included The invention also concerns the preparation of said catalyst. To prepare the catalyst according to the invention, a treatment of the zeolite of structural type EUO, for example the zeolite EU-1, crude synthesis, according to any method known to the person skilled in the art, is first operated, for example a step of calcination under dry air flow, which aims to eliminate the occlusion of the organic structure in the microporosity of the zeolite, then proceeds in at least one ion exchange step for example by at least one solution of NHN 3, so as to eliminate, in part, preferably practically completely, any alkaline cation, in particular sodium, present in the cationic position in the zeolite.

The preparation of the catalyst is continued by mixing the matrix and the zeolite prepared above, then it is transformed. The conversion of the catalyst according to the invention is generally such that the catalyst is preferably in the form of extrudate or bead, in view of its use. The conditions of transformation of the zeolite, the selection of the matrix, possibly the previous crushing of the zeolite, the peptization process, the addition of porogenic agents, the homogenization time, the extrusion pressure if the catalyst is under extruded form , the speed and the time of drying, are determined, by each matrix, according to the well-known rules of the man of the trade, so as to obtain a catalyst preferably in the form of extrudate or pearls.

The preparation of the catalyst is generally continued by a calcination, usually at a temperature comprised between 250 ° C and 600 ° C, included limits, preferably preceded by drying, for example in the furnace, at a temperature generally comprised between the temperature ambient and 250 ° C limits included, preferably between 40 ° C limits included. Said drying is preferably carried out during the rise in temperature necessary to carry out the aforementioned calcination.

The transformation of the structural type zeolite EUO according to the invention, for example the zeolite EU-1, can be carried out on the crude synthesis zeolite, that is to say it contains the organic structure and alkaline cations, generally sodium. In this case the calcination stage under dry air flow, which aims to eliminate the organic structure, and the ion exchange steps for at least one solution of NH4N03 are carried out on the transformed catalyst containing the zeolite and the matrix.

The catalyst obtained after said calcination and transformed into beads or extrudates has mechanical properties such that the crushing value in bed, determined according to the Shell method (SMS 1471-74), is higher than 0.7 Mpa.

The deposit of at least one element of group VIII of the periodic classification of the elements, and possibly of at least one element selected in the group formed by groups IIIA and IVA of the periodic classification of the elements elements, can be carried out at any time of the preparation, either before the transformation, or when mixing the zeolite and the matrix, the zeolite that is mixed to the set constituted by the precursor (s) of the ) element (s) and the matrix, or, preferably, after the transformation.

When the addition of at least one element selected in group VIII and optionally at least one element selected in the group formed by groups IIIA and IVA is effected after the transformation, the aforementioned element (s) may be (n) then be added (s), either before the calcination, or, preferably, after the calcination of the matrix-zeolite mixture. The aforementioned added element (s) is (are) generally deposited, either virtually entirely on the zeolite, or partly on the zeolite and partly on the matrix, that is to say on the zeolite. preferably, almost entirely on the matrix, this being done, in the manner known to man of the trade, by the appropriate selection of the parameters used in making said deposit, such as, for example, the nature of the forerunner of the aforementioned (s) element (s) The deposit of at least one element of group VIII is generally carried out by the technique of dry impregnation, impregnation by excess, or preferably by ion exchange (s). In the case of ion exchange from platinum and / or palladium-based precursors, platinum and / or palladium salts such as exacloroplatinic acid and / or exacloropaládic acid are usually used in the presence or absence of agents competitors, such as, for example, hydrochloric acid. In the case where at least one other metal selected in the group formed by the groups IIIA and IVA of the periodic classification of the elements is also introduced, all the known deposit techniques of the man of the trade and all the precursors agree for the introduction of the additional metal.

In the case where the catalyst contains several elements of group VIII of the periodic classification of the elements, the metals can be introduced, either all in the same way, or by different techniques, and in no matter what the order. In the case where at least one metal selected in the group formed by the groups IIIA and IVA of the periodic classification of the elements is also introduced, the elements of group VIII and groups IHA or IVA can be added separately. or simultaneously in at least one unit stage. When at least one element of the IHA or VAT groups is added separately, it is preferable that it be previously added to the element (to the elements) of group VIII. In the case where the deposition technique used is that of ion exchange, several successive exchanges may be necessary to introduce the required quantities of metals.

Platinum is generally introduced into the matrix in the form of exacloroplatinic acid, but for all noble metal, ammoniated compounds or compounds such as, for example, ammonium chloroplatinate, platinum dicarbonyl dichloride, exacloroplatinic acid, palladium chloride, can also be used. , palladium nitrate.

The use in the present invention of at least one noble metal of the platinum family can by way of example be made possible by the use of ammoniated compounds, in this case, the noble metal will be deposited in the zeolite.

In the case of platinum, mention may be made, for example, of the salts of platinum II tetramines of the formula Pt (NH3) 4X2, the salts of platinum IV of the formula Pt (NH3) eX; the salts of platinum IV halogenopentamines of formula (PtX (NH3) 5) X3; the salts of platinum N tetrahalogenodia inas of formula PtX (NH3) 2; the platinum complexes with the halogens polyketones and the halogenated compounds of formula H (Pt (acac) 2 X); X being a halogen selected from the group consisting of chlorine, fluorine, bromine and iodine, and preferably X being chlorine, and acac representing the group C5H7O2 derived from acetylacetone.

The introduction of the noble metal of the platinum family is preferably effected by impregnation with the aid of an aqueous or organic solution of one of the organometallic compounds mentioned above, among the usable organic solvents, mention may be made of paraffinic, naphthenic or aromatic hydrocarbons, and halogenated organic compounds having for example 1 to 12 carbon atoms per molecule. Mention may be made, for example, of n-heptane, methylcyclohexane, toluene and chloroform. It is also possible to use solvent mixtures.

The additional metal, optionally additionally introduced, selected in the group formed by the elements of groups IIIA and IVA, can be introduced by the intermediary of compounds such as for example chlorides, bromides and nitrates, alkalyls of elements of groups IIIA and IV, that is, for example tin, indium, tin alkali, nitrate and indium chloride.

If this metal is introduced before the noble metal, the metal compound used is generally selected from the group consisting of the halide, nitrate, acetate, tartrate, carbonate and oxalate of the metal. The introduction is then advantageously carried out in aqueous solution. But it can also be introduced with the aid of a solution of an organometallic compound of the metal, for example tetrabutyltin. In this case, before proceeding to the introduction of at least one noble metal, a calcination is carried out under air.

This metal can also be introduced in the form of at least one organic compound selected from the group consisting of the complexes of said metal, in particular the polyketone complexes of the metal and hydrocarbyl metals such as alkyls, cycloalkyls, aryls, alkylaryls and the arylalkyl metals. in the latter case, the introduction of the metal is advantageously effected with the aid of a solution of the organometallic compound of said metal in an organic solvent. It is also possible to use organohalogen compounds of the metal. As metal compounds, mention may be made in particular of tetrabutyltin in the case of tin, and triphenylindium in the case of indium.

The impregnation solvent is selected from the group consisting of paraffinic, naphthenic or aromatic hydrocarbons containing from 6 to 12 carbon atoms per molecule and halogenated organic compounds containing from 1 to 12 carbon atoms per molecule. Mention may be made, for example, of n-heptane, methylcyclohexane and chloroform. It is also possible to use mixtures of the solvents defined above.

The groups of at least one element of group VIII and optionally of at least one element of groups U A or IVA is preferably followed by a calcination under air or oxygen, generally between 250 ° C and 600 ° C included limits, preferably between 350 ° C and 550 ° C included limits, and for a duration comprised between 0.5 and 10 hours inclusive limits, preferably between 1 to 4 hours inclusive limits. It is then possible to carry out a reduction under hydrogen, generally at a temperature comprised between 300 ° C and 600 ° C, preferably between 350 ° C and 550 ° C, inclusive limits, and for a duration comprised between 1 to 10 hours inclusive limits, preferably between 2 and 5 hours inclusive limits, in order to obtain the aforementioned element (s) mainly in the reduced form necessary for the catalytic activity.

For example, one of the preferred methods of preparing the catalyst according to the invention consists in homogenizing at least one EUO structural type zeolite, for example the EU-1 zeolite, in a wet matrix gel (generally obtained by mixing at least one acid and a matrix powder), for example of alumina, for a duration necessary for obtaining a good homogeneity of the obtained paste, for example for a tenth of a minute, after passing said paste through a filial to form extrudates, for example with a diameter between 0.4 and 4 mm. limits included, preferably between 0.4 and 2.5 mm. limits included and preferably still between 0.8 and 2.0 mm. limits included. Then, after drying for a few hours at approximately 120 ° C in the oven and after calcination, for example for approximately 400 ° C, the element (s) of the HIV group and possibly the element (s) of groups IIIA and IVA, for example, platinum, are deposited, for example by ion exchange, with for example, the exacloroplatinic acid in the presence of a competing agent (for example hydrochloric acid) said deposit followed by a calcination, for example for about 2 hours at about 400 ° C .

In the case where the catalyst of the present invention contains sulfur, the sulfur is introduced onto the calcined, calcined catalyst containing the above-mentioned element (s), either in situ prior to the catalytic reaction. , or ex situ. The sulfurization is carried out using any sulfurizing agent well known to the person skilled in the art, such as, for example, dimethyl disulfide or hydrogen sulphide. Eventual sulfiding intervenes after reduction. In the case of sulfidation in situ, the reduction, if the catalyst has not been previously reduced, intervenes before sulphuration. In the case of ex situ sulphidation, the reduction is effected after the sulphuration.

The catalyst according to the invention also has excellent mechanical resistance to crushing, excellent catalytic results in hydrocarbon transformations, such as, for example, the isomerization of the aromatic compounds of 8 carbon atoms, that is to say of mixtures consisting of xylenes and optionally ethylbenzene.

Accordingly, the invention also concerns an isomerization process of an aromatic C8 cut in the presence of the catalyst according to the invention.

The mentioned procedure is generally applied according to the following operating conditions: - a temperature comprised between 300 ° C and 500 ° C inclusive limits, preferably between 320 ° C and 450 ° C included limits and even more preferably between 340 ° C and 430 ° C included limits, - a hydrogen partial pressure comprised between 0.3 and 1.5 MPa including limits, preferably between 0.4 and 1.2 MPa included limits and still preferred between 0.7 and 1.2 MPa included limits, - a total pressure between 0.45 and 1.9 MPa including limits, preferably between 0.6 and 1.5 MPa limit included, - a feed space velocity, expressed in kilogram of charge introduced per kilogram of catalyst per hour, included between 0.25 and 30 i / h1 included limits, preferably between 1 and 1/10 * inclusive limits, and still preferably between 2 and 6 1 / h1 limits included.

The following examples illustrate the invention without, however, limiting the scope.

Example 1: Preparation of the catalyst Cl containing 10.0% by weight of zeolite EU-1 of Si / Al ratio equal to 18.3, 89.7% alumina and 0.29% platinum.

The raw material used is an EU-1, raw synthesis zeolite, comprising the organic component, silicon and aluminum, which have a global Si / Al atomic ratio equal to 13.6, a sodium content by weight in relation to the weight of EU zeolite. -1 dry of approximately 1.5%, corresponding to an atomic ratio Na / Al DE 0.6.

This EU-1 zeolite first undergoes a calcination called dry at 550 ° C under air flow lasting 6 hours. then the solid obtained is subjected to three ion exchanges in a NH 3 10 10 N solution, at approximately 100 ° C for 4 hours for each exchange.

As a result of these treatments, the EU-1 zeolite in the form of NH4 has a global atomic Si / Al ratio equal to 18.3, a sodium content by weight in relation to the weight of dry EU-1 zeolite of 50 ppm, corresponding to an atomic Na / Al ratio of 0.003, a specific surface area measured by the BET method of 407 m2 / g and a porous volume, in nitrogen, measured at -196 ° C and at P / Po = 0.15 of 0.16 m3 of liquid nitrogen per gram.

The EU-1 zeolite is then put into shape by extrusion with an alumina gel so as to obtain, after drying and calcination under dry air, the support constituted of 1.4 mm extrudates. in diameter, containing 10% by weight of zeolite EU-1 in the form of H and 90% alumina, the pore diameter of the catalyst thus prepared, measured by mercury porosimetry, is between 40 and 90 ° C, distribution of the diameters of these mesoporos being monomodal and centered on 70 A °. The crushing value in bed, obtained according to the Shell method, is 1.1 Mpa.

The support thus obtained is subjected to an anion exchange with exacloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to introduce 0.3% by weight of platinum in relation to the catalyst, the wet solid is then dried at 120 ° C during 12 hours and calcined under an expenditure of dry air at the temperature of 500 ° C for one hour.

The catalyst Cl thus obtained contains 10.0% by weight of zeolite EU-1 under form H, 89.7% alumina and 0.29% platinum. It presents, by the metallic phase, a dispersion of 95 %, determined by chemisorption, and a coefficient of distribution of platinum of 0.9, determined by Castaing microprobe.

Example 2: Preparation of the catalyst C2 containing 10.0% by weight of zeolite EU-1 of ratio Si / Al to 31, 89.7% of alumina and 0.28% of platinum.

The raw material used is a zeolite of structural type EUO, the EU-1 zeolite, crude synthesis, containing the organic structure of silicon and aluminum, having a global atomic ratio Si / equal to 28, a sodium content by weight in relation to the weight of dry EU-1 zeolite of approximately 0.4%, which corresponds to an atomic Na / Al ratio of 0.30.

This EU-1 zeolite first undergoes a calcination called dry at 550 ° C under air flow lasting 6 hours.

Then the solid obtained is subjected to three ion exchanges in a solution of NH4N03 ION, of approximately 100 ° C for 4 hours for each exchange.

Following these treatments, the EU-1 zeolite in the form NH4 in a global atomic Si / Al ratio equal to 31, a sodium content by weight in relation to the weight of zeolite EU-1 dry 100 ppm, which corresponds to an atomic Na / Al ratio of 0.008, a surface measured by the BET method of 435 m2 / g and a porous volume, in nitrogen, measured at -196 ° C and at P / Po = 0.15, of 0.18 cm3 of liquid nitrogen per gram.

The zeolite EU-1 is then transformed by extrusion with an alumina gel so as to obtain, after drying and calcination under dry air, the support consisting of 1.4 mm extrudates. in diameter, containing 10% by weight of zeolite EU-1 under form H and 90% alumina. The diameter of the pores of the catalyst thus prepared, measured by mercury porosimetry, is between 100 and 100 A °, the distribution of the diameters of these micropores being mono odal and centered on 330 A °. This difference in porosity between the catalysts Cl and C2 results from the use of different alumina gels. The crushing value in bed, obtained according to the Shell method, is 1.0 MPa.

The support thus obtained is subjected to an anion exchange with exacloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to introduce 0.3% by weight of platinum relative to the catalyst. The wet solid is then dried at 120 ° C for 12 hours and calcined under an expenditure of dry air at the temperature of 500 ° C for one hour.

The catalyst C2 thus obtained contains 10.0% by weight of zeolite EU-1 in the form of H, 89.7% of alumina and 0.28% of platinum. It presents, for the metallic phase, a dispersion of 94%, determined by quimisorción, and a coefficient of distribution of the platinum of 0.92, determined by microprobe of castaning.

Example 3: Preparation of catalyst C3 containing 29.9% by weight of EU-1 zeolite with a Si / Al ratio of 44, 69.8% alumina and 0.29% platinum.

The raw material used is a zeolite of structural type EUO, the zeolite EU-1, crude synthesis, comprising the organic structure of silicon and aluminum, having a global atomic ratio Si / equal to about 44, a content by weight in sodium in relation to the weight of dry EU-1 zeolite of approximately 0.5%, which corresponds to a Na / Al Close atomic ratio of 0.6.

This EU-1 zeolite first undergoes a calcination called dry at 550 ° C under air flow lasting 6 hours.

Then the solid obtained is subjected to three ion exchanges in a solution of NH4NO3 ION, of approximately 100 ° C for 4 hours for each exchange.

As a result of these treatments, the EU-1 zeolite in the form of NH4 has a Si / Al global atomic ratio of about 44, a sodium content by weight in relation to the weight of dry EU-1 zeolite of 100 ppm. which corresponds to an atomic Na / Al ratio of approximately 0.012%, a surface measured by the BET method of 420 m2 / g and a porous volume of hydrogen, measured at -196 fC and at P / Po = 0.15, of 0.17 cm3 of nitrogen liquid per gram.

The zeolite EU-1 is then transformed by extrusion with alumina gel so as to obtain, after drying and calcination under dry air, the support consisting of 1.4 mm extrudates. in diameter, containing 30% by weight of EU-1 zeolite under H form and 70% aluminum. The diameter of the pores of the catalyst thus prepared, measured by mercury porosimetry, is between 40 and 90 A °, the distribution of the diameters of these mesopores being monomodal and centered on 70 A °. the crushing value in bed, obtained according to the Shell method, is 0.89 Mpa.

The support thus obtained is subjected to an anion exchange with the exacloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to introduce 0.3% by weight of platinum relative to the catalyst. The wet solid is then dried at 120 ° C for 12 hours and calcined under an expenditure of dry air at the temperature of 500 ° C for one hour.

The catalyst C3 thus obtained contains 29.9% by weight of EU-1 zeolite, 69.8% of alumina and 0.29% of platinum.

It presents, for the metallic phase, a dispersion of 92%, determined by chemisorption, and a platinum distribution coefficient of 0.94, determined by a Castaing microprobe.

Example 4: Preparation of the C4 catalyst containing 10.0% by weight of EU-1 zeolite with Si / Al ratio of 18.3, 89.6% alumina, 0.28% platinum and 0.14% tin.

In the preparation of the catalyst C4, tin deposits are made after platinum on the support obtained in example 1.

Tin is first deposited on this solid by ion exchange with a solution of tin chloride SnC12 in the presence of a competing agent (hydrochloric acid), so as to obtain 0.15% by weight of tin relative to the catalyst. This deposit is followed by a calcination. A second anion exchange with exacloroplatinic acid is then carried out in the presence of a competing agent (hydrochloric acid), so as to introduce 0.3% by weight of platinum relative to the catalyst. The wet solid is then dried at 120 ° C for 12 hours and calcined under an expenditure of dry air at the temperature of 500 ° C for one hour.

The catalyst C4 thus obtained contains 10.0% by weight of zeolite, 89.6% of alumina, 0.28% of platinum and 0.14% of tin. It presents, for the metallic phase, a dispersion of 0.91%, determined by chemisorption, and a platinum distribution coefficient of 0.89, determined by Castaing microprobe. The resistance to crushing of the catalyst C4 is the same as that measured on the catalyst Cl.

Example 5: Preparation of the C5 catalyst not according to the invention, containing mordenite and 0.3% by weight of platinum.

The starting zeolite is a mordenite of Si / Al ratio = 5.2 elemental mesh volume of 2794 nm3. The zeolite is subjected to three ion exchanges in an NH4NO3 ION solution at approximately 100 ° C for 4 hours, the solid thus obtained contains 25 ppm of sodium.

This zeolite is then transformed by extrusion (extrusion diameter = 1.4 mm.) with an alumina gel so as to obtain, after drying and calcination under dry air, a support containing 10% by weight of mordenite zeolite forms hydrogen and 90% alumina.

This support is subjected to an anion exchange with the exacloroplatinic acid in the presence of a competing agent (hydrochloric acid), in order to deposit 0.3% by weight of platinum in relation to the catalyst. The wet solid is then dried at 120 ° C for 12 hours and calcined under an expenditure of dry air at the temperature of 500 ° C for one hour.

The catalyst C5 thus obtained contains 10.0% by weight of mordenite forms hydrogen, 89.7% of alumina and 0.3% of platinum. The platinum dispersion, measured by chemisorption, is 95% and the coefficient of distribution of the platinum determined by Castaing microprobe is 0.95. the diameter of the pores, measured by porosimetry to mercury, is between 40 and 90 A °, the distribution of diameters of these mesopores being mono odal and centered on 70 A °. The crushing value in bed, obtained according to the Shell method, is 1.5 MPa.

Example: Preparation of the C6 catalyst not according to the invention, containing Zeolite EU-1 and 0.3% by weight of platinum.

The catalyst C6 is prepared according to the same protocol as the catalyst Cl but the last stage of calcination at 500 ° C is suppressed and the preparation is then terminated by a simple drying at 120 ° C.

The measurement of the metal dispersion by oxygen chemisorption would lead, on the Cl catalyst, to a value of 95 %, while not getting more than 43% for the catalyst C6, not according to the invention.

Example 7: Preparation of the C7 catalyst not with orme to the invention, containing EU-1 zeolite and 0.3% by weight of platin.

The catalyst C7 is obtained by tabletting a mixture of zeolite EU-1 as described in example 1 and of an aluminum on which 0.33% by weight of platinum has previously been deposited.

Platinum is deposited on this alumina by ion exchange with exacloroplatinic acid in the presence of a competing agent (hydrochloric acid). The wet alumina is then dried at 120 ° C for 12 hours and calcined under the expenditure of dry air at the temperature of 500 ° C for one hour. The metallic phase has a 99% dispersion measured by oxygen chemisorption. The transformation is then carried out by tabletting.

The tableted catalyst C7 thus obtained contains 10.0% by weight of zeolite EU-1 forms hydrogen, 89.7% aluminum and 0.3% platinum.

The main difference between the catalysts Cl and C7 then lies in the transformation that is not conforming in the case of the catalyst C7. In this case, a Shell fractionation value of 0.3 Mpa is obtained, which is clearly lower than that of the Cl sample.

Example 8: Evaluation of the catalytic properties of the Cl to C7 catalysts in isomerization of an aromatic C8 cut, with 5 g. of catalyst.

The results of the catalysts Cl to C7 have been evaluated in the isomerization of an aromatic C8 cut that contains mainly meta-xylene, ortho-xylene and ethylbenzene with 5 g. of catalyst. The operation conditions are the following: - temperature: 390 ° C. - total pressure: 15 bar, (1 bar = 0.1 Mpa) - partial pressure of hydrogen: 12 bar.

The catalysts are previously treated with a charge containing dimethyl disulfide (DMDS) in the presence of hydrogen, with a concentration such that the sulfur / metal atomic ratio is 1.5 except for the C4 catalyst. The catalyst is then maintained for 3 hours at 400 ° C under the expense of hydrogen then the charge is injected.

The catalysts have been compared in terms of activity (by the approximations to the equilibrium of para-xylene and of ethylbenzene, and by the conversion of ethylbenzene), and in terms of selectivity by the net losses in iso-approximations to the equilibrium of para-xylene .

In addition, parasitic reactions lead to three types of losses: losses to paraffins that result essentially from opening reactions of naphthenic cycles followed by fractionation, losses to aromatics formed by dismutation and transalkylation reactions of 8-atom aromatics of C AC8, and finally, the losses to the naphthenes whose naphthenes of 8 carbon atoms (N8) due to the hydrogenation of the aromatics. The N8 can be recycled, compare the losses by fractionation and dismutation / Transalkylation that includes the naphthenes different to N8 (whose sum constitutes the net losses) taking a base 100, for each of these losses, for the catalyst A not conforming to the invention.

For the calculation of the equilibrium approximations (AEQ), the concentrations of ethylbenzene (% EB) are expressed in relation to the four isomers (AC8), and those of para-xylene (% pX) in relation to the three xylenes isomers.

The equilibrium approximations (AEQ) are defined as follows: pX AEQ (%) = 100X (% pXefluente-% pXcarga) / (% pXequilibrio-% pXcarga) EB AEQ (%) = 100X (% EB? Fluente-% EBcarga) / (% EB? Equilibrium-% EBoarga) The fractionation losses (Pl) are losses in AC8 in the form of paraffins (PAR) from Cl to C8: Pl (% in of effluent) - (% PAR cargaxpesode carga)] / (% AC8aargaxload load) Losses by dismutation / transalkylation (P2) are losses in AC8 in the form of naphthenes other than N8, toluene, benzene and aromatic C9 + (OAN): P2 (% by weight) = 100X [(% OANcfiuontcx effluent weight) - (% OANchargexload load)] / (% AC8loadxload load) The sum of the losses Pl and P2 represents the net losses.

The data presented in table 1 have been obtained from experimental iso-conditions.

TABLE 1 Catalyst Cl C2 C3 C5 C6 'C7 N.C. N.C. N.C. Yes / At 18.3 31 44 MOR 18.3 18.3 Zeolite content (%) 10 10 30 10 10 10 pX AEQ (%) 98.0 97.1 97.8 94.5 97.7 97.9 EB AEQ (%) 90.8 81.2 87.7 86.2 66.1 88.8 EB conversion (%) 5 555..99 52.2 55.4 54.1 44.1 59.8 losses net (% by weight) 5.7 5.2 7.1 6.7 6.3 14.9 N. C. : Not compliant It is noted from the results of Table 1 that the catalysts Cl to C3 according to the invention are much more active than the non-compliant C5 catalyst, since they lead to iso-operating conditions at a pX AEQ of 98.0%, 97.1% and 97.8% respectively (against 94.5% for the C5 catalyst).

In addition, the catalysts according to the invention Cl to C3 have a conversion of ethylbenzene of 55.9%, 52.2% and 55.4% respectively, even much higher than in the case of non-compliant catalyst C6 (44.1%). Finally, the catalysts Cl to C3 present net losses of 5.7%, 5.2% and 7.1% respectively, even much weaker than in the case of the non-compliant C7 catalyst (14.9%) which is even less selective.

In addition, these catalysts have been compared to iso pX AEQ (approximately 95.5%) by varying the mass load costs. These results are presented in Table 2.

TABLE 2 Catalysts Cl C2 C3 C4 C5 Not compliant Yes / Al 18.3 31 44 18., 3 MOR Zeolite content 10 10 30 10 10 pX AEQ (%) 95.5 94.5 95.3 94.8 94.5 net losses (% by weight) 4.7 4.5 5.9 4.4 6.7 fractionation 98 107 103 86 100 dismutation / transalkylation 53.6 43.3 80.4 56.9 100 In iso pX AEQ, table 2 shows that the catalysts Cl to C4 according to the invention are also very much very selective than the non-compliant C5 catalyst. In effect, for a pX AEQ of 95.5% approximately, the net losses are respectively of 4.7%, 4.5%, 5.9% and 4.4% by weight for the catalysts Cl to C4 versus 6.7% by weight for the C5 catalysts. This very important gain in the case of the catalysts according to the invention is found at the level of dismutation / transalkylation losses.

The activity and the selectivity obtained when using the catalysts according to the invention, based on a zeolite of structure EUO, in isomerization of an aromatic C8 cut are still clearly improved in relation to the previous specialty.

In addition, stability tests have been carried out. The catalysts Cl and C6 have been tested under the conditions described above for 800 hours. They have then been downloaded and regenerated under the same conditions: their references are then respectively C1R and C6R. The regeneration consists of practicing a treatment under air at a temperature of 500 ° C in order to burn the coke deposited on the catalyst in the course of 800 hours of reaction. A Root of this regeneration, a second test of 800 hours under load has been made on the catalysts C1R and C6R, in identical operating conditions to those of the first test of 800 hours. The results are presented in Table 3.

TABLE 3 Catalyst: Cl (conforming) C2 (nonconforming) conversion EB (%) at t = 36 h. 55.9 44.1 conversion EB (%) to t = 800h 53.2 39.4 conversion drop EB (%) 4.9 10.6 Catalyst: Cl (conforming) C2 (nonconforming) conversion EB (%) at t = 36 h. 55.0 41.9 conversion EB (%) to t = 800 h. 51.7 36.8 conversion drop EB (%) 6.0 12.2 The catalyst Cl according to the invention exhibits a deactivation (measured by the conversion drop of ethylbenzene) of 4.9% for 800 hours of testing. The regeneration makes it possible to find, for the catalyst Cl, a conversion of ethylbenzene of 55.0% against 55.9 for the fresh catalyst, the non-compliant C6 catalyst is much less stable with 10.6% deactivation for the same number of hours under load. Regeneration is equally less effective.

Through this example, it appears that the catalyst Cl according to the invention, for which the metal of group VIII it is well dispersed on the surface of the catalyst, it is more active and more stable than the non-compliant C6 catalyst.

Example 9: Evaluation of the properties of the catalysts Cl and C5 in isomerization of an aromatic C8 cut, with 60 g. of catalyst.

The results of the catalysts Cl and C5 have been evaluated in the isomerization of an aromatic C8 cut that contains mainly meta-xylene, ortho-xylene and ethylbenzene with go g. of catalyst. The operation conditions are the following: - temperature: 375 ° C, - total pressure: 9 bar, (1 bar = 0.1 Mpa) - H2 / HC: 4 The results obtained in iso-pX AEQ are presented in Table 4.

TABLE 4 Catalyst Cl C5 Yes / Al 18.3 MOR Zeolite content 10.0 10.0 pph (1 / h1) 4 2.51 pX AEQ (%) 93.1 92.91 EB conversion (%) 41.0 46.1 net losses (%) 1.6 4.8 losses by fractionation 69.0 100 dismutation / transalkylation 20 100 From Table 4 it is found that the catalyst Cl according to the invention is much more selective than the non-compliant C5 catalyst since the net losses are 1.6% for Cl against 4.8% for C5.

In addition, the catalyst according to the invention is more active since in iso-pX AEQ one works at a pph of 4 (1 / h1) against a pph of 2.51 (1 / h1) for C5.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Having described the invention as above, it is claimed as property in the following,

Claims (25)

1. Catalyst comprising at least one zeolite of structural type EUO, at least partly in acid form, at least one matrix, at least one metal from group VIII of the periodic classification of the elements, said zeolite comprising silicon and at least one element T selected from the group consisting of aluminum, iron, gallium and boron, with a global at ratio Si / T greater than 5, said catalyst being characterized in that the dispersion of said metal of group VIII is included between 50% and 100% limits included, and the macroscopic distribution coefficient of the said group VIII metal is comprised between 0.7 and 1.3 limits included, the catalyst that has a mechanical resistance such that the crush value in bed is higher than 0.7 Mpa .

2. The catalyst according to claim 1 characterized in that the dispersion of the group VIII metal is comprised between 60 and 100%, and preferably between 70 and 100%.

3. Catalyst according to one of claims 1 to 2, characterized in that the macroscopic distribution coefficient is comprised between 0.8 and 1.2.

4. Catalyst according to one of claims 1 to 3, characterized in that it is transformed in the form of beads or extrudates.

5. Catalyst according to one of claims 1 to 4, characterized in that the structural type zeolite EUO is the zeolite EU-1.

6. Catalyst according to one of claims 1 to 5, characterized in that the element T is selected from the group consisting of aluminum and boron.

7. Catalyst according to one of claims 1 to 6, characterized in that the matrix is alumina.

Catalyst according to one of claims 1 to 7, characterized in that the metal of group VIII is selected from the group consisting of platinum and palladium.

9. Catalyst according to one of claims 1 to 8, characterized in that the zeolite is at least partially in acid form with an at Na / T ratio of less than 0.5.

10. Catalyst according to one of claims 1 to 9, characterized in that it contains from 1% to 90% by weight of at least one zeolite of structural type E.UQ, preferably from 3 to 60% and so most preferred from 4 to 40%.

11. Catalyst according to one of claims 1 to 10, characterized in that the weight content of the or of the metals of group VIII is comprised between 0.01% and 2.0%, preferably between 0.05 and 1.0% in relation to the total weight of the catalyst.

12. Ca-t-al 1-zador- according to one of the pe io vi nia í-on ß 1 a-11 characterized in that it also comprises at least one element selected in the group formed by the groups IIIA and IVA of the periodic classification of the elements.

13. Catalyst according to one of claims 1 to 12, characterized in that the element selected in the group formed by groups IIIA and IVA of the periodic classification is tin and / or indium.

14. Catalyst according to one of claims 1 to 13, characterized in that the content of at least one element selected in the group formed by groups IIIA and VAT of The periodic classification of the elements is between 0.01% and 2.0%, preferably between 0.05 and 1% in relation to the catalyst.

15. Catalyst according to one of claims 1 to 14 characterized in that it comprises sulfur in a content such that the elation of the number of sulfur atoms on the number of metal atoms of group VIII deposited is between 0.5 and 2.

16. Process for preparing the catalyst according to one of claims 1 to 15, characterized in that it comprises a step of treating the zeolite of the crude structural type EUO of synthesis, a step in which the matrix and the aforementioned zeolite are mixed and then said mixture is transformed , a calcination stage generally carried out at a temperature comprised between 250 ° C and 600 ° C, limits included, the deposit of at least one metal of group VIII can be effected at all times of the preparation.

17. Process for the preparation of the catalyst according to claim 16 such that the deposit of the group VIII metal is followed by a calcination carried out at a temperature comprised between 250 and 600 ° C.

18. Method according to one of claims 16 to Characterized in that the group VIII metal is deposited after the calcination step following the transformation of the matrix-zeolite mixture.

19. Method according to one of claims 16 to 18 characterized in that the metal of group VIII is deposited in more than 90% completely on the binder.

20. Method according to one of claims 16 to 19 characterized in that it comprises the deposit of at least one element selected in the group formed by the elements of groups IIIA and IVA, this deposit can be deposited at all times of the preparation.

21. Method according to one of claims 16 to Characterized in that the deposit of at least one element selected in the group formed by the elements of groups IIIA and IVA is effected before depositing the metal of group VIII.

22. Method according to one of claims 16 to 21 characterized in that the sulfur is introduced on the transformed, calcined and reduced catalyst, containing The deposited element (s) is already in situ before the catalytic reaction, or ex situ.

23. Use of a catalyst according to one of claims 1 to 15 or prepared according to one of claims 16 to 22 in a charge isomerization process comprising aromatic compounds of 8 carbon atoms per molecule.

24. Use of a catalyst according to claim 23, characterized in that the filler is selected from a mixture of xylenes, ethylbenzene, a mixture of xylenes and ethylbenzene.

25. Use of a catalyst according to one of claims 23 to 24, characterized in that it is applied at a temperature comprised between 300 and 500 ° C, with a partial pressure of hydrogen comprised between 0.3 and 1.5 MPa, with a total pressure between 0.45 and 1.9. Mpa and a spatial feeding speed between 0.25 and 30 (1 / h1).