FR2787779A1 - Synthesis of EUO zeolites, useful e.g. as catalysts in isomerization reactions of eight carbon aromatic hydrocarbons, uses precursors of structuring agents - Google Patents

Abstract

The synthesis of EUO zeolites is effected in the presence of organic structuring precursors which are less hazardous in use than the structuring agents themselves. The synthetic process involves the mixing, in aqueous solution, of a source of an element X (Si or Ge), a source of an element T, chosen from Al, Fe, Ga, B, Ti, V, Zr, Mo, As, Sb, Cr and Mn, and a monoamine precursor of a structuring agent comprising an alkylated derivative of polymethylene alpha ,w diammonium. Independent claims are also included for the EUO zeolite obtained by the process, and its uses.

Description

I The present invention relates to a process for the preparation of a catalyst

  based on a zeolite with structure EUO, said zeolite being obtained according to a new mode of synthesis, as well as the process for the preparation of said catalyst. The invention also relates to a process for the isomerization of aromatic compounds with 8 carbon atoms also called “C8 aromatic cuts, in the presence of this zeolite-based catalyst of the type

structural EUO.

  The isomerization into xylenes of ethylbenzene requires the presence of a group VIII metal. Optimized formulations based on mordenite and a group VIII metal lead to catalysts with which the parasitic reactions remain non-negligible. For example, mention may be made of the opening of naphthenic rings whether or not followed by cracking or else the dismutation and transalkylation reactions of C8 aromatics which lead to the formation of aromatics which are not desired. It is therefore particularly interesting

  to find new, more selective catalysts.

  The EU-1 zeolite of structural type EUO, already described in the prior art, has a one-dimensional microporous network, the pore diameter of which is 4.1 × 5.7 Å (1 λ = 1 Angstrom = 1.10- 'm ) (c, Atlas of Zeolites Structure

  types ,, W.M. Meier and D.H. Oison, 4th Edition, 1996). On the other hand, N.A.

  Briscoe et al taught in an article in the journal Zeolites (1988, 8, 74) that these one-dimensional channels have side pockets of depth 8.1 A and diameter 6.8 x 5.8 A. The mode of synthesis of the EU-1 zeolite and its physicochemical characteristics have been described in patent EP 42 226. The method of synthesis comprises the mixture of a silicon oxide and / or germanium and an oxide of at least one element chosen from aluminum, iron, gallium, boron, titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium and manganese in the presence of a structuring agent comprising at least one alkylated derivative of polymethylene c-co diammonium of formula R1R2R3 N + (CH2) n N + R4R5R6. The precursors of the alkylated derivative are the related diamine together with alcohols or

alkyl halides.

  Patent application EP 51 318 deals with the TPZ-3 zeolite, which, according to the Atlas of Zeolites Structure types, WM Meier and DH Olson, 4th Edition, 1996, has the same structural type EUO as the EU zeolite. 1. The preparation of the zeolite comprises mixing a soluble alkali metal compound, a 1,6-N, N, N, N ', N, Nhexamethylhexamethylenediammonium compound, a compound capable of giving silica and a compound capable of to give

  alumina, at a temperature above 80 C.

  It has been discovered by the applicant that a catalyst prepared according to the process of the present invention, in the form of extrudates or beads, used in the isomerization reactions of aromatic C8 cuts, comprising at least one metal from group VIII of the periodic table of the elements, at least one zeolite of structural type EUO, characterized in that one uses during the synthesis of the zeolite at least one precursor of the structuring comprising an alkylated derivative of polymethylene a-co diammonium chosen from monoamines, led to performance at least as good, in terms of activity, selectivity, and also in terms of temporal stability, compared to the catalysts of the prior art comprising a zeolite of structural type EUO synthesized using methods described in the prior art and with a significant cost saving in the preparation of the catalyst. This cost saving results from the use of the less expensive precursors and from the reduction in the crystallization time of the EUO zeolite through the use of these precursors. In addition, this process makes it possible to increase safety by the use of precursors which are less dangerous than the structuring itself or that the

precursors of the prior art.

  The catalyst prepared according to the process of the present invention contains at least one element from group VIII of the periodic table of elements, at least one zeolite of structural type EUO, for example a zeolite EU-1, and at least one binder. The EUO structural type zeolite is characterized in that its synthesis is carried out in the presence of at least one precursor of the alkylated derivative of polymethylene cc-o diammonium chosen from monoamines. This zeolite is present at least partly in acid form. The zeolite, of structural type EUO, contains at least one element X chosen from germanium and silicon and at least one element T chosen from the group formed by aluminum, iron, gallium, boron, titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium and manganese, preferably aluminum and boron, the overall atomic ratio X / T being greater than or equal to 5. The catalyst also contains at least one metal from group VIII of the periodic table of the elements, Handbook of Physics and Chemistry, 76 firm edition, preferably chosen from the group formed by palladium and platinum and even more preferably platinum. The catalyst optionally contains at least one metal belonging to the group formed by the elements of groups IB, IIB, IIIA, IVA, VIB and VIIB of the periodic table. In addition, this catalyst is in the form of beads or extrudates. The EUO structural type zeolite is therefore obtained according to a new synthesis mode comprising the mixing in aqueous medium of at least one source of at least one element X chosen from silicon and germanium, of at least one source of at least one element T chosen from aluminum, iron, gallium, boron, titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium and manganese and at least a precursor of the nitrogen structuring

  comprising an alkylated derivative of polymethylene ce- diammonium.

  The invention is characterized in that at least one precursor of the alkylated derivative

  of polymethylene c - to diammonium is chosen from monoamines.

  In addition to the precursors chosen from the monoamines according to the invention, the other group (s) of the structuring agent (s) is (are) generally introduced using any suitable precursor in order to obtain a quaternary ammonium. This (s) precursor (s) is (are) of the F-R-F 'type, where F and F' are identical or different leaving groups such as for example an alcohol function or a halide. By way of example, at least one chosen precursor is also used.

  among alkanediols and alkane dihalides.

  The precursors according to the invention and the other precursors can be preheated together in the reaction vessel or mixed as such with the other reagents. Precursors can be introduced to any

  time of preparation of the zeolitic material.

  Preferably, the precursors are introduced in solution before the addition of the other reagents necessary for the synthesis of the zeolitic material of the type

  structural EUO, for example the EU-1 zeolite.

  In a particular implementation, it may be advantageous to add to the reaction medium seeds S of at least one zeolite. It is possible to add seeds having the structure of the EUO zeolite or having the structure of other accessible and inexpensive zeolites such as for example zeolites of structural type LTA, FAU, MOR, MFI. These seeds can accelerate the crystallization of the EUO structural type zeolite, for example the EU-1 zeolite, from the reaction mixture. The germs can be introduced at any time during the synthesis of the zeolite. Preferably, in the eventual case where the zeolite is synthesized using seeds, said seeds are added after

  homogenization at least in part of the mixture containing the other reagents.

  In another particular implementation, independent or not of the previous implementation, it may be advantageous to add to the reaction medium at least one salt P. Mention may be made, for example, of strong acid radicals such as bromide, chloride , iodide, sulfate, phosphate or nitrate, or weak acid radicals such as organic acid radicals, for example citrate or acetate. This salt can accelerate the crystallization of zeolites of the EUO structural type, for example the EU-1 zeolite from the reaction mixture. In the particular synthesis of EU-1 and TPZ-3 zeolites, of structural type EUO, the aqueous reaction mixture generally has the following molar composition, expressed in the form of oxides: XO2 / T203 (mol / mol) at least 10 OH ' / XO2 (mol / mol) 0.002 to 2.0 Q / XO2 (mol / mol) 0.002 to 2.0 Q / (M * + Q) (mol / mol) 0.1 to 1.0 H2O / XO2 (mol / mol) 1 to 500 P / XO2 (mol / mol) 0 to 5 S / XO2 (g / g) 0 to 0.1 preferably, the reaction mixture has the following composition, expressed in the form of oxides XO2 / T203 (mol / mol) at least 12 OH- / XO2 (mol / mol) 0.005 to 1.5 Q / X02 (mol / mol) 0.005 to 1.5 Q / (M + + Q) (mol / mol) 0, 1 to 1.0 H2O / XO2 (mol / mol) 3 to 250 P / XO2 (mol / mol) O to 1 S / XO2 (g / g) 0.0005 to 0.07 and, even more preferably, the reaction mixture has the following composition, expressed in the form of oxides: X02 / T203 (mol / mol) at least 15 OH '/ XO2 (mol / mol) 0.01 to 1 Q / X02 (mol / mol) 0, 01 to 1 Q / (M + + Q) (mol / mol) 0.1 to 1.0 H2O / XO2 (mol / mol) 5 to 100 P / XO2 (mol / mol) O to 0.25 S / XO2 (g / g) 0.001 to 0.04 o X is silicon and / or germanium, T is at least one element chosen from aluminum, iron, gallium and boron, titanium, vanadium, zirconium , molybdenum, arsenic, antimony, chromium and manganese, M + represents an alkali metal or the ammonium ion, Q represents the aforementioned alkylated derivative of polymethylene (a-) diammonium, introduced using precursors appropriate corresponding containing a monoamine, S represents the zeolite seeds expressed in the dried, calcined or exchanged form,

  P represents the salt, of alkali metal or of ammonium.

  M + and / or Q may be present in the form of hydroxides or acid salts

  inorganic or organic provided that the OH / XO2 criterion is met.

  The invention is characterized in that the organic structuring agent comprising an alkylated derivative of polymethylene o-wo diammonium is introduced using at least one precursor chosen from monoamines. By monoamine is meant any organic compound having an amine function. Said amine function can be primary, secondary or tertiary. Preferably, the precursors are chosen from alkylamines having from 1 to 18 carbon atoms per molecule and preferably having from 1 to 8 carbon atoms per molecule. The alkyamines can be primary, secondary and tertiary. More

  particularly the precursors are chosen from trialkylamines.

  The preferred starting precursors are, inter alia, those which lead to the preferred alkylated polymethylene co-diammonium derivatives, that is to say the alkylated derivatives of hexamethylene ca-oe diammonium and especially the hexamethylene ao diammonium methylated and even more preferably the salts of 1,6-N, N, N, N ', N', N'-hexamethylhexamethylenediammonium having the formula (CH3) 3 N + (CH2) 6 N + (CH3) 3, for example the halide, the hydroxide, the sulfate, silicate, aluminate. For example, preferably, the precursor according to the invention is trimetylamine and the precursor of the other groups

is dibromohexane.

  The preferred alkali metal (M) is sodium. The preferred T element is aluminum.

  The preferred element X is silicon.

  The source of silicon can be any one of which the use is normally envisaged for the synthesis of zeolites, for example silica

  solid powder, silicic acid, colloidal silica or silica in solution.

  Among the powdered silicas that may be used, mention should be made of precipitated silicas, especially those obtained by precipitation from a solution of an alkali metal silicate, such as, Zeosil, or "Tixosil" produced by Rhône-Poulenc, fumed silicas such as "Aerosil" produced by Degussa and, Cabosil>, produced by Cabot and silica gels. Colloidal silicas of various particle sizes can be used, such as those sold under the registered trademarks "LUDOX", Dupont, and <SYTON, de Monsantos. The dissolved silicas which can be used are in particular the soluble glasses or silicates sold commercially containing 0.5 to 6.0 and especially 2.0 to 4.0 moles of SiO2 per mole of alkali metal oxide and the silicates obtained by dissolving silica in a alkali metal hydroxide, a hydroxide

  quaternary ammonium or a mixture thereof.

  The source of aluminum is most preferably sodium aluminate, but aluminum, an aluminum salt, for example chloride, nitrate or sulfate, an aluminum alcoholate or the alumina itself which preferably should be in a hydrated or hydratable form such as colloidal alumina, pseudoboehmite, boehmite, gamma alumina, or trihydrates can

also agree.

  Mixtures of the sources cited above can be used. Combined sources of silicon and aluminum can also be used such

  than amorphous silica-aluminas or certain clays.

  The reaction mixture is usually reacted under autogenous pressure, optionally with the addition of a gas, for example nitrogen, at a temperature between 85 and 250 C until crystals of the zeolite, which can last from 1 minute to several months depending on the composition of the reagents, the heating and mixing mode, the working temperature and the stirring. Agitation is optional, but preferable because it

shortens the reaction time.

  At the end of the reaction, the solid phase is collected on a filter and washed and is then ready for the following operations such as drying, calcination and

ion exchange.

  Thus, in order to obtain the hydrogen form of the zeolite with structure EUO, an ion exchange can be carried out with an acid, especially a strong mineral acid such as hydrochloric, sulfuric or nitric acid, or an ammonium compound such as an ammonium salt such as chloride, sulfate or ammonium nitrate. The ion exchange can be carried out by dilution in one or more stages with the ion exchange solution. The zeolite can be calcined before or after ion exchange or between two ion exchange stages, preferably before ion exchange in order to remove any organic substance

  absorbed, to the extent that ion exchange is facilitated.

  The catalyst prepared according to the process of the present invention, put in the form of beads or extrudates, therefore contains: * at least one zeolite with structure EUO, for example zeolite EU-1, characterized in that one uses during from its synthesis at least one precursor of the alkylated derivative of polymethylene c-wo diammonium chosen from monoamines according to the method described above, * at least one metal from group VIII of the periodic table of elements, preferably chosen from the group consisting of palladium and platinum and even more preferably platinum, * at least one binder, preferably alumina, * optionally at least one metal belonging to the group formed by the elements of groups IB, IIB, IIIA, IVA, VIB and VIIB of the periodic classification of the elements, preferably tin or indium, * possibly sulfur, said catalyst being characterized in that it is prepared according to a new m ode for the synthesis of the EUO structural type zeolite included in the catalyst which makes it possible to reduce its manufacturing cost by reducing its synthesis time with a maximum yield of pure product and by using

  precursors of the organic structurer less expensive than the structuring itself

  even. In addition, the use of precursors less dangerous than the structuring

  increases security during synthesis.

  More precisely, the catalyst prepared according to the process of the present invention, put in the form of beads or extrudates, comprises with respect to the weight of catalyst: * from 1 to 90% inclusive, preferably from 3 to 60% inclusive and even more preferably from 4 to 40% limits inclusive by weight, of at least one zeolite with structure EUO, obtained according to the new synthesis method, comprising at least one element X chosen from germanium and silicon and at least one element T chosen from the group formed by aluminum, iron, gallium, boron, titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium and manganese, preferably

  aluminum and boron, whose atomic ratio X / T is greater than or equal to 5.

  Said zeolite is at least partly in acid form, that is to say in hydrogen form (H +), the sodium content being such that the atomic ratio Na / T is less than 0.5, preferably less than 0, 1, even more preferably less than 0.02, * from 0.01 to 2% limits inclusive and preferably from 0.05 to 1.0% limits inclusive by weight, of at least one metal from group VIII of the periodic classification of the elements, preferably chosen from the group formed by platinum and palladium and even more preferably platinum * possibly from 0.01 to 2% limits inclusive and preferably between 0.05 and 1.0% bounds included by weight, of at least one metal from the group formed by groups IB, IIB, IIIA, IVA, VIB and VIIB of the periodic table of the elements, preferably chosen from the group formed by tin and indium , * possibly sulfur, the content of which is such that the ratio of the number of sulfur atoms on the number of group VIII metal atoms deposited is between 0.5 and 2 limits inclusive, * the complement to 100% by weight of at least one binder, preferably alumina. Any zeolite with EUO structure known to a person skilled in the art and obtained according to the method of synthesis described in this patent is suitable for the catalyst prepared according to the process of the present invention. Thus for example, the zeolite used as a base for preparing said catalyst can be the crude synthetic EU-1 zeolite having the required specificities concerning the X / T ratio. Calcination can generally be carried out, then at least one ion exchange in at least one NH4NO3 solution so as to obtain a

  zeolite with more or less residual sodium content.

  The binder (or matrix) included in the catalyst prepared according to the process of the present invention generally consists of at least one element chosen from O the group formed by clays, magnesia, aluminas, silicas, titanium oxide, Boron oxide, zirconia, aluminum phosphates, titanium phosphates, zirconium phosphates and silica aluminas. Can also

  use charcoal. Preferably the binder is an alumina.

  The EUO structural type zeolite, for example the EU-1 zeolite, included in the catalyst according to the invention, is at least in part, preferably practically totally, in acid form, that is to say in hydrogen form ( H +), the sodium content preferably being such that the Na / T atomic ratio is less than 0.5, preferably less than 0.1, even more so

preferred less than 0.02.

  The metals can be introduced either all in the same way or by different techniques, at any time of the preparation, before or after shaping and in any order. In addition, intermediate treatments such as for example calcination and / or reduction can be applied

  between deposits of different metals.

  At least one element of group VIII is introduced into the zeolite or onto the binder,

  preferably on the binder before or after shaping.

  A preferred method consists in making a mixture of the matrix and the zeolite followed by shaping. The shaping is generally followed by calcination, generally at a temperature of between 250 ° C. and 600 ° C., limits included. At least one element from group VIII of the periodic table is introduced after this calcination, preferably by selective deposition on the binder. Said elements are deposited practically at more than% totally on the binder in the manner known to a person skilled in the art by checking the parameters used during said deposition, such as for example the nature of the precursor used to effect said deposition. Optionally, at least one element belonging to the group formed by the elements of groups 1B, 11iB, IIIA, IVA, VIB and VIIB is added. The elements of group VIII and of groups 1B, IIB, IIIIA, IVA, VIB and VIIB can be added either separately at any stage of the preparation of said catalyst or simultaneously in at least one unitary stage. When an element at least of groups IB, IIB, IIIA, IVA, VIB and VIIB It is added separately, it is preferable that it is added before

the element of group VIII.

  At least one element from group VIII is preferably deposited on the zeolite-binder mixture previously formed by any process known to those skilled in the art. Such a deposition is for example carried out by the technique of dry impregnation, excess impregnation or ion exchange. All the precursors are suitable for the deposit of these elements. For example, preferably, an anion exchange will be carried out with hexachloroplatinic acid and / or hexachloropalladic acid in the presence of a competing agent, for example hydrochloric acid. With such precursors, the metal is practically more than 90% completely deposited on the binder and it has good dispersion and good macroscopic distribution across the grain of catalyst, which constitutes a preferred method of

preparation.

  Optionally at least one other metal chosen from the group formed by the elements of groups IB, IIB, IIIA, IVA, VIB and VIIB of the periodic table of the elements is also introduced. All the deposition techniques known to those skilled in the art and all the precursors are suitable for

  the introduction of at least one additional metal.

  One of the preferred methods for preparing the catalyst, prepared according to the process of the present invention, consists in kneading the zeolite in a wet matrix gel (generally obtained by mixing at least one acid and a matrix powder), by example alumina, for a time necessary to obtain good homogeneity of the dough thus obtained, that is to say for ten minutes, then to pass the dough through a die to form extrudates, for example diameter between 0.4 and 4 mm terminals included. Then after drying, for example for a few hours at approximately 120 ° C. in an oven and after calcination, for example for two hours at approximately 500 ° C., at least one element, for example platinum, is deposited, for example by anion exchange with hexachloroplatinic acid in the presence of a competing agent (for example hydrochloric acid), said deposit being followed by calcination for example during

about 2 hours at around 500 C.

  Platinum is generally introduced into the matrix in the form of hexachloroplatinic acid, but for any noble metal can also be used ammonia compounds or compounds such as for example ammonium chloroplatinate, dicarbonyl platinum dichloride, acid

  hexahydroxyplatinic, palladium chloride, palladium nitrate.

  The use in the present invention of at least one noble metal of the platinum family can, for example, be achieved by the use of compounds

  ammonia. In this case, the noble metal will be deposited in the zeolite.

  In the case of platinum, mention may, for example, be made of the platinum 11 tetramine salts of formula Pt (NH3) 4X2, the platinum IV hexamine salts of formula Pt (NH3) 6X4; the halogenopentamine platinum IV salts of formula (PtX (NH3) 5) X3; the platinum N tetrahalodiamine salts of formula PtX4 (NH3) 2; platinum complexes with halogen-polyketones and halogenated compounds of formula H (Pt (acac) 2X); X being a halogen chosen from the group formed by chlorine, fluorine, bromine and iodine, and preferably X being chlorine, and acac representing the group C5H702 derived from acetylacetone. The introduction of the noble metal of the platinum family is preferably carried out by impregnation using an aqueous or organic solution of one of the organometallic compounds mentioned above. Among the organic solvents which can be used, mention may be made of paraffinic, naphthenic or aromatic hydrocarbons, and halogenated organic compounds having, for example, from 1 to 12 carbon atoms per molecule. Mention may be made, for example, of n-heptane, methylcyclohexane, toluene and chloroform. You can also use the

solvent mixtures.

  The additional metal, optionally introduced in addition, chosen from the group formed by the elements of groups IB, IIB, IIIA, IVA, VIB and VIIB, can be introduced via compounds such as for example chlorides, bromides and nitrates, alkyls of elements of groups IB, IIB, IIIA, IVA, VIB and VIIB, ie for example tin and indium, alkyl tin, nitrate and indium chloride. This metal can also be introduced in the form of at least one organic compound chosen from the group consisting of the complexes of said metal, in particular the polyketonic complexes of the metal and the hydrocarbylmetals such as alkyls, cycloalkyls, aryls, alkylaryls. and arylalkyl metals. In the latter case, the introduction of the metal is advantageously carried out using a solution of the organometallic compound of said metal in an organic solvent. Organohalogenated metal compounds can also be used. As metal compounds, mention may be made in particular of tetrabutyltin in the case of tin, and triphenylindium in the case of

indium.

  The impregnating solvent is chosen 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. Can also

  use mixtures of the solvents defined above.

  It is also possible to envisage introducing at least one metal chosen from the group formed by the elements of groups IB, IIB, IIIA, IVA, VIB and VIIB. This additional metal can optionally be introduced at any time during the preparation,

  preferably before depositing one or more Group VIII metals.

  If this metal is introduced before the noble metal, the compound of the metal used is generally chosen from the group consisting of the halide, the nitrate, the acetate, the tartrate, the carbonate and the oxalate of the metal. The introduction is then advantageously carried out in aqueous solution. However, it can also be introduced using a solution of an organometallic compound of the metal, for example tetrabutyltin. In this case, before proceeding with the introduction of

  minus a noble metal, calcination is carried out in air.

  The shaping of the catalyst according to the invention is generally such that the catalyst is preferably in the form of extrudates or beads for the purpose of its use. The preparation of the catalyst generally ends with a calcination, usually at a temperature of between approximately 250 ° C. and 6000 ° C. inclusive, for a period of approximately 0.5 to 10 hours, preferably preceded by drying, for example at oven, at a temperature included

  between room temperature and 250 C, preferably between 40 and 200 C.

  Said drying step is preferably carried out during the rise in

  temperature necessary to carry out said calcination.

  In the case where the catalyst of the present invention contains sulfur, the sulfur is introduced onto the shaped catalyst, calcined, containing the one or more

  previously mentioned metals, either in situ before the catalytic reaction, or ex-

  if you. Possible sulfurization occurs after reduction. In the case of in situ sulfurization, the reduction, if the catalyst has not been previously reduced, takes place before the sulfurization. In the case of ex-situ sulfurization, the reduction is then carried out. Sulfurization is carried out in the presence of hydrogen using any sulfurizing agent well known to those skilled in the art, such as for example dimethyl sulfide or hydrogen sulfide. For example, the catalyst is treated with a feedstock containing dimethyl sulfide in the presence of hydrogen, with a concentration such that the sulfur / metal atomic ratio is 1.5. The catalyst is then maintained for approximately 3 hours at approximately 400 ° C. under a flow of hydrogen before the injection of the charge. The present invention also relates to a process for the isomerization of C8 aromatic cuts consisting of a mixture of xylenes and optionally ethylbenzene, in the presence of the catalyst prepared according to the process of

present invention.

  The catalyst prepared according to the process of the present invention is used in the isomerization reactions of an aromatic C8 cut, comprising for example either only a mixture of xylene (s), or

  only ethylbenzene, a mixture of xylene (s) and ethylbenzene.

  Said method is generally implemented according to the following operating conditions: * a temperature between 300 C and 500 C limits included, preferably between 320 C and 450 C limits included and even more preferably between 340 0C and 4300C limits included, * a partial pressure of hydrogen of between 0.3 and 1.5 MPa limits included, preferably between 0.4 and 1.2 MPa limits included and, in a more preferred manner, between 0.7 and 1.2 MPa limits included , * a total pressure between 0.45 and 1.9 MPa limits included, preferably between 0.6 and 1.5 MPa limits included, * a space supply speed, expressed in kilograms of charge introduced per kilogram of catalyst and per hour, between 0, 25 and 30h- 'terminals included, preferably between 1 and 10h'1 terminals included, and

  more preferably between 2 and 6 h-i terminals included.

  The catalyst used in the present invention, in the form of beads or mechanically resistant extrudates, consisting of at least one zeolite of structural type EUO, for example zeolite EU-1, obtained from the mode of synthesis described in present patent, of at least one binder, of at least one metal chosen from the elements of group VIII of the periodic table of the elements, said metal preferably being deposited on the binder, exhibits excellent catalytic performance in transformation of hydrocarbons, in terms of activity, selectivity and temporal stability, such as for example in isomerization of aromatic C8 cuts, that is to say mixtures consisting of xylenes and optionally ethylbenzene. The EUO type zeolites used for obtaining this catalyst are obtained for much shorter synthesis times than the EUO type zeolites described in the prior art. This particular synthesis method therefore leads to a cost saving on the preparation of the catalyst, all the more since the precursors used are less expensive than the structuring itself, and this without degradation of the catalytic properties of said catalyst. In addition, the precursors are less dangerous than the structuring which makes it possible to increase safety during

synthesis.

  The following examples illustrate the invention.

  Example 1: Syntheses of EU-1 (or TPZ-3) zeolites with a similar Si / AI ratio

of 15.

  Hexamethonium bromide is used as the usual organic structuring agent for the two EU-1 zeolites with an EUO structure referenced Z1 and Z2 and obtained respectively in the absence and in the presence of germs. These zeolites were

synthesized for comparison.

  The EU-1 zeolites of EUO structure referenced Z3 and Z4 were obtained according to the new synthesis method described in this patent. They were respectively obtained in the absence and in the presence of germs and by using a set of precursors of the organic structuring agent containing at least one

  precursor chosen from monoamines.

  The EU-1 zeolites of EUO structure referenced Z5 and Z6 were synthesized using a set of organic structuring precursors comprising a diamine, for comparison. They were respectively obtained in the absence

and in the presence of germs.

  The seeds used are seeds of EU-1 zeolites of EUO structure, of

  Si / Al ratio = 25 and Na-Hx form (Hx = hexamethylammonium).

  The synthesis mixture has the following composition: SiO2 (mol) 60 A1203 (mol) 2 Na2O (mol) 10 DBrH (mol) 0 or 20 TMA (mol) 0 or 40 TMHMDA (mol) 0 or 20 CH31 (mol) 0 or 40 HxBr2 (mol) 0 or 20 H20 (mol) 2800 germs / SiO2 (g / g) 0 or 0.04

  Hx Br2 = hexamethonium bromide = Me3-N- (CH2) 6-N-Me3 2+ (Br) 2.

  DBrH (dibromohexane) and TMA (trimethylamine) are precursors of

hexamethonium bromide.

  THMDA (1-6 tetramethylhexamethylene diamine) and CH31 are precursors of hexamethonium iodide. To obtain the zeolite Z1, the solution A of silica and structuring agent is prepared by diluting 12.026 9 of hexamethonium bromide (Fluka, 97%) in 57.419 9 of water and then adding 14.501 g of colloidal silica sol (Ludox AS40 , Dupont, 40% SiO2). 0.985 g of solid sodium hydroxide (Prolabo, 99%) and 0.715 g of solid sodium aluminate (Prolabo, 46% A1203, 33% Na2O) are then dissolved in 7.177 g of water to form solution B. add solution B to solution A with stirring then 7.177 g of water. Mix until homogenized. The resulting mixture is reacted in a 125 ml autoclave with stirring for 96 h at 180 C under autogenous pressure. After cooling, the product is filtered and washed with 0.5 liter of water

  demineralized and then dried in a ventilated oven at 120 C.

  The same is done for obtaining the zeolite Z2, but in this case,

  add the EU-1 zeolite seeds after homogenization of solution A + B.

  The preparations of zeolites Z3 and Z4 are respectively the same as zeolites Z1 and Z2, but precursors of hexamethonium bromide are used. Solution A is therefore prepared by diluting 8,023 9 of dibromohexane and 8,450 9 of trimethylamine in 57,419 g of water and then

  adding 14.501 g of colloidal silica sol (Ludox AS40, Dupont, 40% SiO2).

  In the case of zeolites Z5 and Z6, solution A is prepared by diluting 5.43 g of THMDA and 8.97 g of CH31 in 55.80 g of water and then adding 14.07 g of soil

  colloidal silica (Ludox AS40, Dupont, 40% SiO2).

  The X-ray diffraction and chemical analysis results show that in all six cases a pure EU-1 zeolite is obtained (crystallinity of 100% +3,

  Si / AI ratio close to 15), of maximum yield (approximately 15%).

  Zi Z2 Z3 Z4 Z5 Z6 (comp.) (Comp.) (Inv.) (Inv.) (Comp.) (Comp.) Structuring HxBr2 HxBr2 precursor precursor precursor precursor

TMA TMA THMDA THMDA

  Germ no no no yes no yes Crystallization time 125 96 110 85 122 93 The crystallization times of zeolites Z1 to Z6 are respectively 125, 96, 110, 85, 122 and 93 hours. These results make it possible to dissociate the influence of the presence of germs from that of the use of the precursors of the structuring agent. The use of this new synthesis method leads to a gain in terms of safety by the use of less toxic products but also in terms of cost by using less expensive precursors than the structuring and

  by reducing the synthesis time.

  These six zeolites are used in the preparation of the catalysts of the four

following examples.

  Example 2 Preparation of Catalyst A Not in Accordance with the Invention, Containing

  the EU-1 zeolite referenced Zl and 0.3% by weight of platinum.

  The raw material used is the crude synthetic EU-1 zeolite referenced Zl, comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 14.2, a weight content

  in sodium relative to the weight in dry EU-1 zeolite of approximately 1.5%.

  This EU-1 zeolite first undergoes so-called dry calcination at 550 ° C. under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a solution of NH4NO3 O10N, at approximately 100 C for 4 hours

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.8, a sodium content by weight relative to the

  weight of dry EU-1 zeolite of 50 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, a support S1 consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-1 zeolite in H form and 90% alumina.

  The support S1 thus obtained is subjected to an anionic exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 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 a

  dry air flow at 500 C for one hour.

  The catalyst A thus obtained contains by weight, 10.0% of EU-1 zeolite forms

  hydrogen, 89.7% alumina and 0.3% platinum.

  Example 3 Preparation of Catalyst B Not in Accordance with the Invention, Containing

  the EU-1 zeolite referenced Z2 and 0.3% by weight of platinum.

  The raw material used is the crude synthetic EU-1 zeolite (Z2), comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 13.9, a sodium content by weight

  relative to the weight in dry EU-1 zeolite of approximately 1.5%.

  This EU-1 zeolite first undergoes a so-called dry calcination at 5500C under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a NH4NO3 10ON solution, at around 1000C for 4 hours.

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.5, a weight content of sodium relative to the

  weight of dry EU-1 zeolite 45 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, a support S2 consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-1 zeolite in H form and 90% alumina.

  The support S2 thus obtained is subjected to an anionic exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 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 a flow of dry air at the temperature of 500 ° C. for one hour. The catalyst B thus obtained contains by weight, 10.0% of EU-1 zeolite forms

  hydrogen, 89.7% alumina and 0.3% platinum.

  Example 4 Preparation of Catalyst C According to the Invention, Containing the

  EU-1 zeolite referenced Z3 and 0.3% by weight of platinum.

  The raw material used is the crude synthetic EU-1 zeolite (Z3), comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 14.4, a sodium content by weight.

  relative to the weight in dry EU-1 zeolite of approximately 1.5.

  This EU-1 zeolite first undergoes so-called dry calcination at 550 ° C. under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a NH4NO3 10ON solution, at approximately 100 C for 4 hours.

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.7, a weight content of sodium relative to the

  weight of dry EU-1 zeolite of 30 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, a support S3 consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-1 zeolite in H form and 90% alumina.

  The support S3 thus obtained is subjected to an anionic exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 0.3% by weight of platinum relative to the catalyst. The wet solid is then dried at 1200C for 12 hours and calcined under a

  dry air flow at 500 C for one hour.

  The catalyst C thus obtained contains by weight, 10.0% of EU-1 zeolite hydrogen form, 89.7% of alumina and 0.3% of platinum. Example 5 Preparation of Catalyst D According to the Invention, Containing the

  EU-1 zeolite referenced Z4 and 0.3% by weight of platinum.

  The raw material used is the crude synthetic EU-1 zeolite (Z4), comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 14.2, a sodium content by weight.

  relative to the weight in dry EU-1 zeolite of approximately 1.5.

  This EU-1 zeolite first undergoes so-called dry calcination at 550 ° C. under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a solution of NH4NO3 10N, at approximately 100 C for 4 hours.

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.6, a sodium content by weight relative to the

  weight of dry EU-1 zeolite of 40 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, an S4 support consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-i zeolite in H form and 90% alumina.

  The support S4 thus obtained is subjected to an anion exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 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 a

  dry air flow at 500CO for one hour.

  The catalyst D thus obtained contains by weight, 10.0% of EU-1 zeolite forms

  hydrogen, 89.7% alumina and 0.3% platinum.

  Example 6: Preparation of catalyst E not in accordance with the invention, containing the EU-1 zeolite referenced Z5 and 0.3% by weight of platinum. The raw material used is the crude synthetic EU-1 zeolite (Z5), comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 14.2, a sodium content by weight.

  relative to the weight in dry EU-1 zeolite of approximately 1.5.

  This EU-1 zeolite first undergoes so-called dry calcination at 550 ° C. under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a NH4NO3 10ON solution, at approximately 100 C for 4 hours.

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.7, a weight content of sodium relative to the

  weight of dry EU-1 zeolite of 40 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, an S5 support consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-1 zeolite in H form and 90% alumina.

  The support S5 thus obtained is subjected to an anionic exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 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 a

  dry air flow at 500 C for one hour.

  The catalyst E thus obtained contains by weight, 10.0% of EU-1 zeolite forms

  hydrogen, 89.7% alumina and 0.3% platinum.

  Example 7 Preparation of Catalyst F Not in Accordance with the Invention, Containing

  the EU-1 zeolite referenced Z6 and 0.3% by weight of platinum.

  The raw material used is the crude synthetic EU-1 zeolite (Z4), comprising the organic structuring agent, silicon and aluminum, having an overall Si / AI atomic ratio equal to 13.8, a sodium content by weight

  relative to the weight in dry EU-1 zeolite of approximately 1.5.

  This EU-1 zeolite first undergoes so-called dry calcination at 550 ° C. under air flow for 6 hours. Then the solid obtained is subjected to three ion exchanges in a NH4NO3 10ON solution, at approximately 100 C for 4 hours.

for each exchange.

  At the end of these treatments, the EU-1 zeolite in NH4 form has an overall atomic Si / AI ratio equal to 18.4, a sodium content by weight relative to the

  weight of dry EU-1 zeolite 45 ppm.

  The EU-1 zeolite is then formed by extrusion with an alumina gel so as to obtain, after drying and calcination in dry air, an S6 support consisting of extrudates of 1.4 mm in diameter, which contains by weight 10% of

  EU-1 zeolite in H form and 90% alumina.

  The support S6 thus obtained is subjected to an anionic exchange with hexachloroplatinic acid in the presence of a competing agent (hydrochloric acid), so as to deposit 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 a

  dry air flow at 500 C for one hour.

  The catalyst F thus obtained contains by weight, 10.0% of EU-1 zeolite forms

  hydrogen, 89.7% alumina and 0.3% platinum.

  Example 8: Evaluation of the catalytic properties of catalysts A, B, C, D,

  E and F in isomerization of an aromatic C8 cut.

  The performances of catalysts A, B, C, D, E and F were evaluated in the isomerization of an aromatic C8 cut containing mainly meta-xylene, ortho-xylene and ethylbenzene. The operating conditions are as follows: - 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 feed containing dimethyl disulfide (DMDS) in the presence of hydrogen, with a concentration such that the sulfur / metal atomic ratio is 1.5. The catalyst is then maintained for 3 hours at 400 C under flow

  hydrogen then the charge is injected.

  The catalysts are tested in the laboratory, with 5 g and without recycling

hydrogen.

  The catalysts were compared in terms of activity (by the equilibrium approaches of para-xylene and ethylbenzene, and by the conversion of ethylbenzene), and in terms of selectivity by the net losses at iso- approach to

Balance of para-xylene.

  The parasitic reactions lead to three types of losses: losses towards paraffins resulting essentially from reactions of opening of naphthenic cycles followed by cracking, losses towards aromatics formed by reactions of disproportionation and transalkylation of aromatics with 8 carbon atoms ( AC8), and finally the losses to naphthenes including naphthenes with 8 carbon atoms (N8) due to the hydrogenation of aromatics. N8 can be recycled, we will compare losses by cracking and disproportionation / transalkylation including naphthenes other than N8 (the sum of which constitutes the net losses) by taking a base 100 for the losses

  net of catalyst A not in accordance with the invention.

  For the calculation of equilibrium approaches (EQA), the paraxylene concentrations (% pX) are expressed, relative to the three xylene isomers. The equilibrium approach (AEQ) is defined as follows: pX AEQ (%) = 100 x (% pXeffluent -% pXcharge) / (% pXequilibre -% pXcharge) Losses due to cracking (P1) are losses in AC8 in the form of paraffins (PAR) from Cl to C8: P1 (% weight) = 100 X [(% PARefuentXweight of effluent) (% PARchargeXweight of charge)] / (% AC8chargeXweight of charge) Losses by disproportionation / transalkylation (P2) are losses of AC8 in the form of naphthenes other than N8, toluene, benzene and C9 + aromatics (OAN) P2 (% weight) = 100 X [(% OANeuentxweight of effluent) - (% OANchargexweight of load )] / (% AC8chargeXload weight)

  The sum of losses P1 and P2 represents the net losses.

  The data presented in table 1 were obtained at experimental isoconditions.

Table 1

  Catalysts ABCDEF (comp.) (Comp.) (Inv.) (Inv.) (Comp.) (Comp.) PX AEQ (%) 98, 1 98.3 98.0 97.8 98.3 98.2 conversion EB (%) 59.6 58.8 59.5 59.3 59.4 59.6 It can be seen from the results in Table 1 that the catalysts C and D in accordance with the invention lead to results comparable to those obtained

  with catalysts A, B, E and F not in conformity.

  Furthermore, these catalysts were compared to a lower pX AEQ (approximately, 5%) by varying the mass flow rates of feed. These results are

shown in Table 2.

Table 2

  Catalysts ABCDEF pX AEQ (%) 95.5 95.2 95.7 95.1 95.5 95.3 net losses 4.9 4.7 5.0 5.0 4.6 4.8 4.9 (% by weight) A iso pX AEQ lower, Table 2 confirms the results presented in the

* Table 1 and shows that the catalysts are all equally selective.

  The activity and the selectivity obtained during the use of catalysts C and D, based on zeolites with EUO structure, obtained using precursors of the organic structuring agent in isomerization of an aromatic C8 cut are therefore comparable to those of catalysts containing zeolites of EUO structure with a close Si / AI ratio and obtained according to a mode of synthesis during which

  the organic structuring itself is used as described in the prior art.

  This result is also verified in the case of the use of precursors

containing a diamine.

  Finally, catalysts A, B, C, D, E and F were compared in terms of temporal stability, always under the experimental conditions described at the beginning of this

  example and over a period of 400 hours.

  The stability is evaluated from the evolution of the conversion of ethylbenzene.

  The results are presented in Table 3.

Table 3

  ABCDEF catalyst EB conversion (%) at t = 36 h 59.6 59.8 59.5 59.3 59.4 59.6 EB conversion (%) at t = 400 h 57.6 57.7 57.3 57 , 4 57.5 57.6 drop in EB conversion (%) 3.3 3.5 3.6 3.2 3.2 3.4 It can be seen that the deactivation of the six catalysts A, B, C, D, E and F over 400 hours is comparable. The catalytic properties (activity, selectivity and stability) of the six catalysts are comparable. The introduction of this new mode of synthesis of the EUO structural type zeolite in the preparation of this catalyst for isomerization of the aromatic C8 cuts is therefore of considerable benefit in terms of cost since the precursors are less expensive and that the synthesis time of the zeolite is reduced and while retaining its catalytic properties. In addition, the use of these precursors of the structuring containing

  a monoamine limits the risks linked to toxicity.

Claims (20)

  1. Process for the preparation of a catalyst comprising at least one element from group VIII of the periodic table of elements, at least one binder and at least one zeolite of structural type EUO comprising at least one element X chosen from silicon and germanium and at least one element T chosen from aluminum, iron, gallium, boron, titanium, vanadium, zirconium, molybdenum, arsenic, antimony, chromium and manganese, characterized in that said zeolite is prepared by reaction of an aqueous mixture comprising at least one source of at least one element X, at least one source of at least one element T, and at least one precursor of a structuring agent comprising an alkyl derivative of polymethylene as- diammonium chosen from monoamines.   2. Method according to claim 1 characterized in that the alkylated derivative of polymethylene a-) diammonium introduced using precursors during the synthesis of the zeolite has the formula: R1R2R3 N + (CH2) n N + R4RsR6, n being included between 3 and 12 and R1 to R6, identical or different, which may represent alkyl or hydroxyalkyl radicals having from 1 to 8 atoms   carbon, up to five radicals Ri to R6 can be hydrogen.   3. Method according to one of claims 1 to 2 wherein the alkylated derivative of   polymethylene ca-w diammonium is an alkylated hexamethylenediammonium.   4. Method according to one of claims 1 to 3, wherein the alkylated derivative of   polymethylene ac-o diammonium is a salt of N, N, N, N ', N', N'-hexa-   methyl-1,6-hexamethylenediammonium.   5. Method according to one of claims 1 to 4, wherein the precursor of   alkylated derivative of polymethylene a-co diammonium chosen from monoamines is a trialkylamine.   6. Method according to one of claims 1 to 5, wherein the precursor   chosen from monoamines is trimethylamine (TMA).   7. Method according to one of claims 1 to 6 wherein at least one structuring precursor chosen from dihalides is also used. of alkane and alkanediols.   8. The method of claim 7 wherein the precursor is dibromohexane.   9. Method according to one of claims 1 to 8 wherein is added to the   reaction mixture of seeds S of at least one zeolite.   10. Method according to one of claims 1 to 9 wherein is added to   reaction mixture at least one salt P of alkali metal or ammonium.   11. Method according to one of claims 1 to 8 wherein the mixture   reaction with the following molar composition: XO2 / T203 (mol / mol) at least 10 OH / X02 (mol / mol) 0.002 to 2.0 Q / X02 (mol / mol) 0.002 to 2.0 Q / (M + + Q ) (mol / mol) 0.1 to 1.0 H2O / XO2 (mol / mol) 1 to 500 P / X02 (g / g) 0 to 5 S / XO2 (g / g) 0 to 0.1 o M represents an alkali metal or ammonium and Q represents the derivative   alkylated polymethylene c - o diammonium introduced using precursors.   12. Method according to one of claims 1 to 11 wherein is introduced into minus a binder.   13. Method according to one of claims 1 to 12 wherein is introduced into   minus one metal from group VIII of the periodic table.   14. Method according to one of claims 1 to 13 wherein is introduced into   minus one element chosen from platinum and palladium.   15. Method according to one of claims 1 to 14 in which at least one element chosen from the elements of groups IB, IIb, IIIA, IVA is introduced,   VIB and VIIB of the periodic table.   16. Method according to one of claims 1 to 15 wherein is introduced sulfur.   17. Method according to one of claims 1 to 16 comprising an implementation   forms the catalyst in the form of beads or extrudates.   18. Method according to one of claims 1 to 17 as it comprises a step   for treating the synthetic EUO structural type zeolite of synthesis, a step in which the binder and said zeolite are mixed and then said mixture is shaped, a calcination step generally carried out at a temperature between 250 ° C. and 600 ° C., the deposit of at least one metal from group VIII of the periodic table of elements which may be performed at any time.   19. Catalyst comprising a EUO structure zeolite prepared according to one of claims 1 to 18.   20. Use of a catalyst according to claim 19 in a process for isomerizing a cut of aromatic hydrocarbons with 8 carbon atoms, at a temperature between 300 and 500 C, with a partial pressure of hydrogen between 0.4 and 1.2 MPa, with total pressure between 0.45 and 1.9 MPa and with space feed speed between 0.25 and 30h '.