MXPA99004575A - Dealuminised nu-86 zeolite and its use in the conversion of hydrocarbons - Google Patents

Abstract

The invention concerns a NU-86 zeolite, containing silicon, and at least one element T selected from the group formed by aluminium, iron, gallium and boron, preferably aluminium, characterised in that the element T has been extracted from the structure and in that it has a global atomic Si/T greater than about 20. The extraction of the element T from the zeolite structure (or network) is effected by at least a thermal treatment. optionally carried out in the presence of water vapour, followed by at least an acid attack, by at least a mineral or organic acid solution, or by a direct acid attack. The invention also concerns a catalyst comprising said zeolite at least partly in acid form and the use of said catalyst in hydrocarbon conversion, in particular in the oligomerization of olefins.

Description

ZEQ ITA NU-86 DESALUMINATED AND ITS USE IN THE CONVERSION OF HYDROCARBONS DESCRIPTION OF THE INVENTION The invention is concerned with a zeolite NU-86, comprising silicon and at least one element T chosen from the group consisting of aluminum, iron, gallium and boron, preferably aluminum, characterized in that the element T has been extracted from the structure and because it has an overall atomic ratio greater than about 20. Extraction of the element T from the zeolitic structure (or network) is carried out by at least one heat treatment, possibly in the presence of water vapor, followed by at least one acid attack by at least one solution of a mineral or organic acid or by a direct acid attack. The invention also concerns a catalyst comprising the zeolite at least partly in acid form and the use of the catalyst in the conversion of hydrocarbons, in particular the oligomerization of olefins of 2 to 8 carbon atoms (ie comprising 2 to 8 carbon atoms per molecule). The synthesis of zeolite NU-86 has been described by ICI in the application EP-A2-463 768. The zeolite NU-86 is synthesized in general in the presence of sodium cations and an organic structure which is either octamethonium dibromide or nonamethonium dibromide.

REF. 30273 octamethonium dibromide nonamethonium dibromide The composition of the samples of zeolites NU-86 so prepared have atomic proportions Si / Al between 8.5 and 16 and in general proportions of Na / Al greater than 8%. The structural type of this zeolite has not been officially attributed by the synthesis committee of the IZA (International Zeolite Association). However, according to works published in the ninth international congress of Zeolitas by J.L. Casci, P.A. Box et M.D. Shannon ("Proceedings of the 9th International Zeolite Conference, Montreal 1992, Eds R. Von Ballmoos et al., 1993 by Buttherworth) shows that: • the zeolite NU-86 has a three-dimensional microporous system, • this three-dimensional microporous system is constituted of straight channels where the opening of the pore is delimited by 11 T atoms (T is a tetrahedral atom chosen mainly from the group consisting of Si, Al, Ga and Fe), straight channels delimited alternately by openings of 10 and 12 T atoms and sinusoidal channels also delimited alternatively by openings of 10 and 12 atoms T. The term opening means pores of 10, 11 or 12 tetrahedral atoms (T) of pores consisting of 10, 11 or 12 sides.The determination of diameter of the pores present in the zeolite NU-86 has led to the following values: 4.8 x 5.8 for the pores of 10 sides, 5.7 x 5.7 for the pores of 12 sides and 5.5 x 6.2 for the pores of 11 sides. s pore diameters, zeolite NU-86 belongs to the category of zeolites of average pore diameters. The invention is concerned with the zeolite NU-86, wherein the element T has been extracted from the structure by at least one heat treatment, possibly in the presence of water vapor, followed by at least one acid attack by at least one a solution of a mineral or organic acid or by a direct acid attack by at least one solution of a mineral or organic acid, as well as any catalyst comprising the zeolite. The invention is also concerned with the use of such a catalyst in the conversion of hydrocarbons, in particular oligomerization of olefins. Surprisingly, the zeolite NU-86, at least in part, preferably almost completely, in acid form and comprises a Si / T ratio greater than about 20, leads, after its incorporation into the catalyst, to catalytic and in particular activities, stability and improved selectivities in the hydrocarbon conversion reactions in relation to the catalysts of the prior art and in particular in relation to the non-dealuminated zeolites NU-86 described in the European patent application EP-A2-Q 463, 768, as well as later demonstrated in the examples herein. The invention is concerned with a zeolite NU-86, comprising silicon and at least one element T chosen from the group consisting of aluminum, iron, gallium and boron, preferably aluminum, characterized in that the element T has been extracted from the structure and because it has an overall atomic Si / T ratio greater than about 20, more preferably greater than about 20, and even more preferably comprised between about 20 and about 300. The invention is also concerned with a catalyst comprising at least one zeolite NU-86, wherein the element T has been extracted from the structure and at least in part, preferably almost completely, in acid form, comprising silicon and at least one element T chosen from the group consisting of aluminum, iron , gallium, boron, preferably aluminum and at least one matrix (or bond). Preferably, the overall atomic Ti / T proportion of the dealuminated zeolite is greater than about 20, preferably greater than about 20, and even more preferably between about 20 and about 300. The catalyst optionally also comprises at least one element chosen from the group formed by the groups such as IB and VIII of the periodic classification of the elements, preferably chosen from the group formed by Ag, Ni and Pd, Pt preferably Ni, Pd or Pt. The matrix is chosen in general from among the elements of the group consisting of clays (for example, natural clays such as kaolin or bentonite), magnesias, aluminas, silicas, titanium oxide, boron oxide, zirconia, aluminum phosphates, phosphates of titanium, zirconium phosphates and silica-aluminas and carbon, preferably between the elements of the group consisting of aluminas and clays. The X-ray diffraction diagrams of the zeolite NU-86 are given in the European patent application EP-A2-0.463.768. As is known in the art, a zeolite NU-86 has main lines of X-ray diffraction of its structure, but the intensity of these lines is susceptible to vary depending on the form in which the zeolite is, without however possessing data on the membership of the zeolite to the structure. Thus, the zeolite NU-86 where the element T has been extracted from the structure according to the invention has main lines of its structure, such as are given by the European patent application EP-A2-0.463.768 with an intensity of lines that may be different from what is indicated in the aforementioned patent. When it is comprised in the catalyst according to the invention, the zeolite NU-86 according to the invention is at least partly, preferably practically completely, in acid form, ie in hydrogenated form (H +). The atomic ratio Na / T is generally lower than 0.7% and preferably lower than 0.6% and even more preferred lower than 0.4%. The catalyst according to the invention generally contains from 10 to 99% and preferably from 20 to 95% of zeolite NU-86 wherein the element T has been extracted from the structure at least partly in acid form. In the case where the catalyst of the present invention contains at least one element of groups IB and VIII of the periodic classification of the elements, the weight content of the element (s) is generally comprised between 0.01 and 10. %, preferably between 0.05 and 7% and even more preferably between 0.10 and 5%. The complement for 100% by weight generally consists of the matrix part in the catalyst. The global Si / T atomic ratio of the zeolite as well as the chemical composition of the samples are determined by X-fluorescence and atomic absorption. From the X-ray diffraction diagrams, the total surface area of the signal is measured for each sample. an angular interval (2?) of 6 to 40 °, then, in the same zone, the surface of the lines in number of pulses for a step-by-step recording of 3 seconds with steps of 0.02 ° (2?) . The proportion of these two values, surface of the lines of the total line / surface is characteristic of the amount of crystallized matter in the sample. This proportion or "cup of peaks" is then compared for each sample treated with a cup of reference peaks arbitrarily considered as fully crystallized (100%). The cup of crystallinity is then expressed in percent in relation to a reference that is important to choose well, since the relative intensity of the lines varies depending on the nature of the proportion and the position of the different atoms in the structural unit and in particular of the cations and the structure. In the case where the measurements made in the examples of the present invention, the reference chosen is the 'form calcined in dry air and exchanged 3 times, successively by an ammonium nitrate solution of the zeolite NU-86. It is also possible to estimate the microporous volume from the amount of nitrogen adsorbed at 77 ° K for a partial portion P / Po equal to 0.19, as an indicator. The invention is also concerned with the preparation of the zeolite NU-86 wherein the element T is extracted from the structure and the catalyst. To prepare the zeolite NU-86, wherein the element T is extracted from the structure according to the invention, in the preferred case where T is Al, ie to prepare the dealuminated zeolite NU-86 in the preferred case according to With the invention, where T is aluminum, two dealumination methods can be employed, starting from the raw synthesis NU-86 zeolite comprising the organic structure. They are described later in the present. However, any other method known to one skilled in the art is also contemplated within the scope of the invention. The first method of direct acid attack comprises a first stage of calcination under a flow of dry air at a temperature generally comprised between about 450 and 550 ° C, which has the purpose of eliminating the organic structure present in the microporosity of the zeolite, followed by of a treatment step by an aqueous solution of a mineral acid such as HN03 or HCl or organic such as CH3C02H. This second stage can be repeated as many times as necessary in order to obtain the desired dealuminium. Between these two steps, it is possible to carry out one or several ion exchanges by at least one solution of NH4NO3, in order to eliminate at least in part, practically the alkali cation, in particular sodium, practically total. Likewise, at the end of the dealumination treatment by direct acid attack it is possible to carry out at least one or more ion exchanges for at least one solution of NH4NO3, in order to eliminate residual alkaline cations and in particular sodium. To obtain the desired Si / Al ratio it is necessary to choose the operating conditions well; from this point of view, the most critical parameters are the temperature of the treatment by the aqueous acid solution, the concentration of the latter, the nature, the ratio between the amount of acid solution and the mass of zeolite treated, the duration of the treatment and the number of treatments performed.

The second method referred to as heat treatment (in particular in water vapor or "water vapor") + acid attack, comprises, first, calcination under a flow of dry air, at a temperature generally comprised between about 450 and 550 ° C, which aims to eliminate the organic structure occluded in the microporosity of the zeolite. Then, the solid thus obtained is subjected to one or several ion exchanges by at least one solution of NH4NO3, in order to eliminate at least partially, preferably practically completely, the alkali cation, in particular the sodium present in cationic position in the zeolite. The zeolite thus obtained is subjected to at least one cycle of dealumination of the structure, which comprises at least one heat treatment carried out optionally and preferably in the presence of steam at a temperature generally comprised between 550 and 900 ° C and possibly followed by at least one acid attack by an aqueous solution of a mineral acid or organic The calcination conditions in the presence of water vapor (temperature, water vapor pressure and duration of treatment), as well as post-calcification acid attack conditions (duration of attack, acid concentration, nature of the acid used, and the ratio between the volume of acid and the mass of zeolite) are adapted in order to obtain the desired level of dealumination. With the same object, one can also act on the number of acid attack heat treatment cycles that are carried out. In the preferred case where T is Al, the dealumination cycle of the structure comprising at least one thermal treatment step carried out optionally and preferably in the presence of water vapor and at least one attack stage in an acid medium of the NU-86 zeolite can be repeated as many times as necessary to obtain the dealuminated NU-86 zeolite having the desired characteristics. Also, according to the thermal treatment carried out optionally and preferably in the presence of water vapor several successive acid attacks with acid solutions of different concentrations can be put into operation. A variant of this second calcination method may consist in carrying out the thermal treatment of the zeolite NU-86 containing the organic structure at a temperature generally comprised between 550 and 850 ° C, optionally and preferably in the presence of water vapor. In the case where the stages of calcination of the organic structure and dealumination of the structure are carried out simultaneously. Then, the zeolite is optionally treated by at least an aqueous solution of a mineral acid (for example, HN03 or HCl) or organic acid (CH3C02H for example). Finally, the solid thus obtained can be subjected to at least one ion exchange for at least one solution of NH4N03, in order to eliminate practically any alkaline cation, in particular sodium, present in the cationic position in the zeolite. The catalyst preparation can be carried out according to any method known to one skilled in the art. In general, it is obtained by mixing the matrix and the zeolite, then by shaping. The possible element of the group formed by group IB and VIII of the periodic classification of the elements can be introduced either before the shaping, either during mixing or on the zeolite itself before mixing or preferably , after putting in shape. Shaping is generally followed by calcination, generally at a temperature between 250 and 600 ° C. The eventual element of the set formed by groups IB and VIII of the periodic classification of the elements can be introduced after calcination. In any case, the element is in general deposited at choice either preferably in a practical way entirely on the zeolite, either in a practical way totally on the matrix, either partly on the zeolite and partly on the matrix, this choice it is carried out in the manner known to the person skilled in the art, by the parameters used during the deposit or for example, the nature of the precursor chosen to carry out the deposit. The element of groups IB or VIII, preferably chosen from the group consisting of Ag, Ni, Pd and Pt, preferably Ni, Pd or Pt, can likewise optionally be deposited on the zeolite-matrix mixture previously put into shape by any procedure known to one skilled in the art. A reservoir as such is generally effected by the technique of impregnation to dryness of ion exchange (s) or coprecipitation. In the case of ion exchange from silver-based precursors, nickel or platinum, are usually used silver salts such as chlorides or nitrates, a complex tetramine silver or nickel salts, such as chlorides, nitrates, acetates or formates. This cation exchange technique can also be used to directly deposit the metal on the zeolite powder, before its eventual mixing with a matrix. The eventual deposit of the element (elements) of groups IB and VIII is generally followed by a calcination under air or oxygen, generally at a temperature between 300 and 600 ° C, preferably between 350 and 550 ° C and for a time interval between 0.5 and 10 hours, preferably between 1 and 4 hours.

In the case where the catalyst contains several metals, the latter can be introduced either in the same way, either by different techniques, before or after the shaping and regardless of the order. In the case where the technique used is ion exchange, several successive exchanges may be necessary to introduce the required amounts of metals. For example, one of the preferred methods of preparing the catalyst according to the invention consists in kneading the zeolite in a wet matrix gel (generally obtained by mixing at least one acid and a matrix powder), for example alumina. , for a time interval necessary for obtaining a good homogeneity of the paste thus obtained, for example for a dozen minutes, then passing the pulp through a row to form extruded products, for example of a diameter between 0.4 and 4 mm. Then, after drying for a few minutes at 100 ° C in an oven and after calcination, for example, for 2 hours at 400 ° C, the optional element, for example nickel, can be deposited for example by ion exchange, the deposit is followed by a final calcination, for example for 2 hours at a temperature of 400 ° C.

The formation of the catalyst according to the invention is generally such that the catalyst is preferably in the form of pellets, aggregates, extrudates or balls, in view of its use. The preparation of the catalyst is generally completed by a calcination, called final calcination, usually at a temperature between 250 and 600 ° C, preferably preceded by drying, for example, in an oven at a temperature generally comprised between room temperature and 250 ° C, preferably between -40 and 200 ° C. The drying step is preferably for a period of time to raise the temperature necessary to effect the calcination. It is possible to proceed immediately to a reduction under hydrogen atmosphere, generally at a temperature comprised between 300 and 600 ° C, preferably between 350 and 550 ° C and for a time interval comprised between 1 and 10 hours, preferably between 2 and and 5 hours, in order to obtain the element of group IB and VIII mainly in reduced form necessary for the catalytic activity. A reduction as such may take place either ex situ or in situ, relative to the place of use of the catalyst in a given reaction. The invention is also concerned with the use of the catalyst in the conversion of hydrocarbons, in particular in the oligomerization of olefins of 2 to 8 carbon atoms. Indeed, the catalyst according to the invention comprising the dealuminated zeolite NU-86, allows in particular to obtain: 1) a good quality supercharger, 2) carburetor fuel of excellent quality, 3) diesel fuel for very high quality diesel engine, good quality, from. light olefins of 2 to 8 carbon atoms. The starting olefins for use as such may come from any convenient source. They can also be produced by conversion of methanol. Thus, the charges that can be used are the following: a) the freshly prepared charge, which comprises, in most cases, methanol and possibly water (in all water / methanol proportions); It is first sent to a catalytic decomposition zone or is transformed into water and into light olefins consisting mainly of propene, then secondly, after separation of the formed water the light olefins are sent to an oligomerization zone where they are transformed to a mixture of supercharger and bases for carburetor and diesel engine. b) the freshly prepared cargo consists of light olefins of 2 to 8 carbon atoms from a disintegration unit, either from a steam disintegration unit, either from a catalytic dehydrogenation unit, or from any other source of provisioning; this recent charge is then sent directly to the oligomerization section where it is transformed into a mixture of supercarburant and bases for carburetor and diesel engine. c) the freshly prepared cargo consists of a mixture of the two preceding cargoes. In the catalytic decomposition zone, the conversion of methanol to water and of light olefins is generally carried out in the vapor phase in the presence of an acid zeolitic catalyst or an acid molecular sieve operating either in a fixed bed, or preferably in a fluidized catalytic system at a temperature of about 450 to 650 ° C (preferably between 530 and 590 ° C), under a pressure of 0.01 to 1 MPa (preferably 0.05 to 0.5 MPa), with a charge of liquid charge (speed space) of about 5 to 100 catalyst volumes per hour. The so-called oligomerization reaction is carried out in the liquid phase, in the supercritical phase or in the gas phase, in the presence of an acid zeolitic catalyst according to the invention arranged in the form of a fixed bed, at a temperature of approximately 50 to 400 ° C (from preference between 150 and 350 ° C), under a pressure of 2 to 10 MPa (preferably between 3 to 7 MPa), with a cost of liquid hydrocarbons (space velocity) of approximately 0.3 to 4 volumes per volume of catalyst per hour . The following examples illustrate the invention without limiting the scope, however.

Example 1: Preparations of zeolite H-NU-86/1 according to the invention The raw material used is a zeolite NU-86, which has a global Si / Al atomic ratio equal to 10.2, a sodium content by weight corresponding to an atomic ratio of Na / Al (in%) equal to 30.8. This NU-86 zeolite initially undergoes calcination to dryness at 550 ° C under a flow of dry air for 10 hours. Then, the solid obtained is subjected to four ion exchanges in a solution of NH4N03 at approximately 100 ° C for 4 hours for each exchange. The solid thus obtained is designated NH4-NU-86 and has a Si / Al ratio = 10.4 and a Na / Al ratio = 1.3%. Its other physicochemical characteristics are summarized in table 1.

The zeolite NH4-NU-86 is then subjected to a hydrothermal treatment, in the presence of 100% steam at 650 ° C for 4 hours. The zeolite then undergoes an acid attack with the aid of 7 N nitric acid, at approximately 100 ° C for 4 hours, in order to extract the extra-network aluminic species formed during the hydrothermal treatment. The volume V of the nitric acid solution (in ml) is equal to 10 times the weight P of dry NU-86 zeolite (V / P = 10). At the end of these treatments, zeolite H-NU-86/1 under form H has a global atomic Si / Al ratio of 27.5 and a Na / Al ratio of less than 0.2%. These crystallographic and adsorption characteristics are reported in Table 2, later in the present.

This table shows that after the steps of treatment with saturated steam and acid attack, the zeolite NU-86 retains a good crystallinity and a surface area (SBET) still relatively high.

Example 2: Preparation of the catalyst Cl according to the invention The zeolite H-NU-86/1 obtained in example 1 is immediately put into shape by extrusion with an alumina gel in order to obtain, after drying and low calcination. dry air, the catalyst Cl containing 70% zeolite H-NU-86/1 and 30% alumina.

Example 3: Preparation of zeolite H-NU-86/2 according to the invention Raw material used in the same zeolite NU-86 as used in example 1. This zeolite NU-86 undergoes, at the beginning, a calcination Called to dryness at 550 ° C under a flow of dry air for 10 hours. Then, the solid obtained is subjected to an ion exchange in a 10 N NH4N03 solution, at approximately 100 ° C for 4 hours. This operation is repeated three times in succession. The zeolite NU-86 is then subjected to a treatment using a 0.8 N nitric acid solution at a temperature of about 100 ° C for 5 hours. The volume V of the nitric acid solution (in ml) is equal to 10 times the weight P of dry NU-86 zeolite (V / P = 10). After these treatments the zeolite obtained is called H-NU-86/2. It is in its H form and has a global atomic Si / Al ratio equal to 20.3 and a Na / Al ratio equal to 0.7%. Its crystallographic and adsorption characteristics are summarized in Table 3 below in the present.

Table 3 Example 4: Preparation of the catalyst C2 according to the invention The zeolite H-NU-86/2 obtained in example 4 is immediately put into shape by extrusion with an alumina gel in order to obtain, after drying and calcination, under dry air, catalyst C2 containing 70% zeolite H-NU-86/2 and 30% alumina by weight.

Example 5: Preparation of zeolite H-NU-86/3 according to the invention The raw material used is the same zeolite NU-86 as used in example 1. This zeolite NU-86 undergoes at first a calcination to dryness at 550 ° C under a flow of air and nitrogen for 10 hours. Then, the solid obtained is subjected to an ion exchange in a 10 N NH 4 NO 3 solution, at approximately 100 ° C for 4 hours. This operation is repeated three times in succession. The zeolite NU-86 is then subjected to a treatment with a 2 N nitric acid solution, at approximately 100 ° C, for 5 hours. The volume V of the nitric acid solution added (in ml) is equal to 10 times the weight P of the dry NU-86 zeolite (V / P = 10). At the end of these treatments the zeolite obtained is called H-NU-86/3. It is in its H form and has a global Atomic Si / Al ratio equal to 26.2 and a Na / Al ratio equal to 0.6%. These crystallographic and adsorption characteristics are summarized in Table 4 below in the present.

Table 4 Example 6: Preparation of zeolite H-NU-86/4 according to the invention The raw material used is the same zeolite NU-86 as used in example 1. This zeolite NU-86 initially suffers a calcination to dryness at 550 ° C under a flow of air and nitrogen for 10 hours. Then, the solid obtained is subjected to an ion exchange in a solution of NH4N03 ION, at approximately 100 ° C for 4 hours. This operation is repeated three times in succession. The zeolite NU-86 is then subjected to a treatment with a solution of 8.5 N nitric acid, at approximately 100 ° C, for 5 hours. The volume V of the added nitric acid solution (in ml) is equal to 10 times the weight P of the dry NU-86 zeolite (V / P = 10). After these treatments the zeolite obtained is called H-NU-86/4. It is in its H form and has a global atomic Si / Al ratio equal to 40.3 and a Na / Al ratio equal to 0.15%. These crystallographic and adsorption characteristics are summarized in Table 5 below in the present.

Table 5 Example 7: Preparation of the C3 catalyst according to the invention The zeolite H-NU-86/4 obtained in example 6 is immediately put into shape by extrusion with an alumina gel in order to obtain after drying and calcination under air dry, catalyst C3 containing 70% zeolite H-NU-86/4 and 30% alumina by weight.

Example 8: Preparation of the C4 catalyst not in accordance with the invention The zeolite NU-86 used in this example is the zeolite NH4-NU-86 prepared in example 1 of the present invention. However, in the present example, zeolite NU-86 does not undergo any dealumination. The zeolite NH4-NU-86 obtained in Example 1 is then put into shape by extrusion with an alumina gel in order to obtain, after drying and calcination under dry air, the C4 catalyst containing 70% by weight of zeolite H- NU-86 and 30% alumina.

Example 9: Evaluation of the catalytic properties in the pyrolysis of methylocyclohexane of the catalysts Cl, C2, C3 according to the invention and of the catalyst C4 which is not of the invention. The catalytic evaluations are carried out in a fixed bed, under atmospheric pressure. The charge used is methylcyclohexane. In the series of catalytic tests in which the results are grouped in Table 4, the pph, that is the spatial velocity of the charge, the methylcyclohexane (expressed in grams of toluene injected per gram of catalyst per hour) varies in order to obtain a comparable conversion in the 4 tests. The reaction temperature is kept constant equal to 500 ° C. Table 6 The results of Table 6 show that the catalysts according to the invention Cl and C3 are more selective than the C4 catalyst of the prior art. In particular, the selectivities of the products (toluene + C8 +), which are undesirable products that reveal the catalyst's tendency to carry out hydrogen transfer, which is an undesirable reaction, are weaker than in the case of the non-compliant C4 catalyst. with the invention Example 10: Evaluation of the catalytic properties in the propylene oligomerization of the catalysts Cl, C2, C3 according to the invention and the C4 catalyst of the prior art. The catalytic evaluations are carried out in a fixed bed, under a pressure of 5.5 MPa of nitrogen and at a temperature of 300 ° C with a WH of 1 hour-1. The load used is a C3 cut of steam pyrolysis (5% propane, 95% propylene). Table 7 The reaction temperature is sufficiently high (300 ° C), the variation of the Si / Al ratio of the active phases NU-86 does not influence the activity of the catalysts Cl, C2 and C3 according to the invention and C4 of the technique previous. The results of Table 7 show that the catalysts according to the invention, Cl, C2, C3 are more selective with respect to the production of the diesel cutting than the C4 catalyst of the prior art. The increase of the selectivity in front of the cut of diesel is accompanied in addition to a significant increase of the cetane index of this cut. It is noted that, in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers.

Claims (15)

1. Claims Having described the invention as above, the content of the following claims is claimed as property: 1. Modified zeolite NU-86, comprising silicon and at least one element T selected from the group consisting of aluminum, iron, gallium and boron, characterized in that the element T has been extracted from the structure from the raw synthesis zeolite NU-86 and because an overall atomic Si / T ratio between 20 and 300.
2. 2. The zeolite according to claim 1, characterized because the element T is aluminum.
3. 3. The preparation of the zeolite according to any of claims 1 to 2, from the raw synthesis zeolite NU-86 comprising the organic structure, by means of the direct acid attack method, by means of at least one solution of a mineral or organic acid.
4. 4. The preparation of the zeolite according to claim 3, characterized in that it comprises the following steps: a) calcination under dry flow of crude synthesis NU-86 zeolite comprising the organic structure at a temperature comprised between 450 ° C and 550 ° C, b) acid attack by at least one solution of a mineral or organic acid.
5. 5. The preparation of the zeolite according to any of claims 1 to 2, from the crude synthesis NU-86 zeolite comprising organic structure, by thermal treatment method and acid attack, by means of at least one solution of a mineral or organic acid.
6. The preparation according to claim 5, characterized in that it comprises the following steps: a) heat treatment of the crude synthesis NU-86 zeolite comprising organic structure at a temperature comprised between 550 ° C and 850 ° C, b ) acid attack by at least one solution of a mineral or organic acid.
7. The preparation according to any of claims 5 to 6, characterized in that the heat treatment is carried out in the presence of water vapor.
8. The modified NU-86 zeolite obtained according to the process according to any of claims 3 to 7.
9. 9. A catalyst comprising at least one matrix and at least one zeolite according to any of claims 1 2, characterized in that it separates, in accordance with any of claims 3 to 7, at least in part in acid form.
10. The catalyst according to claim 9, characterized in that it also comprises at least one element of groups IB and VIII of the periodic classification of the elements.
11. The catalyst according to claim 10, characterized in that the element is chosen from the group consisting of Ag, Ni and Pt.
12. The catalyst according to any of claims 9 to 11, characterized in that the matrix is chosen from the elements formed by clays, magnesia, aluminas, silicas, titanium oxide, boron oxide, zirconia, aluminum phosphates, phosphates of titanium, zirconium phosphates and silica-aluminas and carbon.
13. 13. The catalyst preparation according to any of claims 9 to 12, characterized in that it is a mixture of the matrix and the zeolite, then by shaping.
14. 14. The use of a catalyst according to any of claims 9 to 12, characterized in that it is prepared according to claim 13 in the conversion of hydrocarbons.
15. 15. The use according to claim 13, for the oligomerization reaction of olefins of 2 to 8 carbon atoms in liquid phase, in supercritical phase or in gas phase, the catalyst is arranged in the form of a fixed bed at a temperature comprised between 50 and 50. and 400 ° C, under a pressure comprised between 2 and 10 MPa and with an expenditure of liquid hydrocarbons comprised between 0.3 and 4 volumes per volume of catalyst per hour.