Aromatization catalyst with high KL zeolite content

Abstract

The present invention relates to a process for preparing an aromatization catalyst comprising at least 70% of a KL zeolite, a SiO2 silica-based high temperature resistant oxide and a Group VIIIB metal, the process employing a hydrothermal treatment of the support in the presence of steam. The invention also relates to the specific support obtained, to said aromatization catalyst and to a process for aromatizing at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising a C6-C8 alkane fraction using the aromatization catalyst.

Description

Field of the Invention

[0001] The present invention relates to a catalyst composed of a microporous material formed in a binder consisting of at least one silica source, in the form of an extrudate, sheet or bead, which contains at least 70% by mass of KL zeolite (structure type LTL). Prior Art

[0002] Zeolites are crystalline aluminosilicate materials with an ordered microporosity formed by a three-dimensional arrangement of SiO4 4- and AlO4 5- tetrahedra, thus providing a wide variety of structures. The International Zeolite Association (IZA) has classified zeolites according to their structure (structure type). Zeolites are widely used in industry for adsorption, separation, catalysis or ion exchange. KL zeolite is a zeolite of the LTL structure type, containing a one-dimensional microporous system with a pore size of 12 T atoms (T is silicon or aluminum). The cation used to compensate the structural charge is K + . For use in industrial processes, zeolites are formed into objects with larger dimensions than the zeolite crystals, which facilitates their handling and also the passage of the feedstock in the reactor. It is very difficult to form pure KL zeolite and obtain a product with good mechanical strength. Usually, in order to obtain shaped bodies with a high proportion of KL zeolite, traditional methods use clay, alumina or silica and mix and form them with the zeolite. The nature of the selected binder not only affects the mechanical strength of the catalyst, but also affects the performance of the catalyst.

[0003] The preparation of catalysts from KL zeolite in the presence of silica is a known practice.

[0004] Patent US 4 830 732 specifically proposes a method for obtaining a shaped material containing KL zeolite. This method requires mixing KL zeolite with a silica source or a pseudoboehmite source, and then forming the mixture by combining mixing and extrusion. Aluminum nitrate is added to increase the water sensitivity of the catalyst (WSI = water sensitivity index).

[0005] Patent US 5 354 933 proposes a method for obtaining a shaped material containing KL zeolite. This method requires mixing KL zeolite with silica, and then forming the mixture by combining mixing and extrusion. The percentage of KL zeolite relative to the total weight of KL zeolite and silica is 83%. Subsequently, platinum and one or more halogen compounds are applied. This patent states that when the XANES peak intensity of Pt is greater than or equal to 0.4 and the resulting dealumination rate is greater than or equal to 3%, the performance of the catalyst will be improved. No structural data is recorded.

[0006] Patent US 6 207 042 proposes a method for obtaining a shaped material containing KL zeolite. This method requires mixing KL zeolite with silica and Methocel, and then shaping the mixture by combined mixing and extrusion. The percentage of KL zeolite based on the total mass of KL zeolite and silica is 83%, and a single silica source - colloidal sol - is used. In addition, the preparation of the catalyst support requires multiple washing operations to remove the residual alkali generated by the silica precursor and processing aids. Fluorine or chlorine-based halogen compounds are used. This patent does not provide any data on the mechanical strength of the resulting extrudate. The catalyst impregnated onto the washed material shows better stability and shortens the cycle time.

[0007] Patent US 8 263 518 proposes a shaped material in the form of an extrudate containing KL zeolite and silica. The mechanical strength of the resulting extrudate is greater than 3 lb / mm (1.3 daN / mm). This increase in mechanical strength is attributed to the use of zeolite in the form of aggregates with a size between 1.4 µm and 6 µm. In addition, this process requires the use of fluorine or chlorine-based halogen compounds.

[0008] Patent application WO 2019 / 217054 A1 describes the preparation of a catalyst for the aromatization of C6-C8 fractions, which catalyst contains KL zeolite, a binder (silica in the examples), platinum, and halide. This patent shows that if some of the intermediate calcination steps are omitted, the performance of this catalyst is the same as that of the catalyst prepared under standard conditions (where the preparation method includes three calcination steps).

[0009] Patent application US 2018 / 169638 relates to a platinum catalyst on KL zeolite and a high-temperature resistant oxide-type support, the preparation method of which includes a washing step to enrich the catalyst with K or Cs. The micropore volume of this catalyst is 0.015 to 0.05 cc / g, and the SBET is 100 to 170 m² / g. This catalyst also contains chlorine and fluorine.

[0010] Patent application US 2014 / 008833 describes a renewable catalyst containing zeolite (preferably KL, preferably exchanged with barium) and a binder, characterized by a high SBET and a high pore volume, according to a preparation scheme including zeolite ion exchange.

[0011] The C6-C8 fraction aromatization catalysts described in the prior art basically consist of zeolite (preferably KL zeolite) shaped in a silica binder. The active metal can be platinum. Various preparation methods have been reported: ion exchange of KL zeolite, or the presence of a washing operation (to reduce the Na content), or the presence of halogen compounds. The support and the catalyst are subjected to one or more calcination-type heat treatments.

[0012] For the aromatization of C6 / C8 fractions, in terms of catalyst performance, silica has proven to be the best binder choice. The nature of silica is more neutral than alumina. Alumina-based binders have more hydroxyl sites than silica and will promote cracking reactions, which are not desired.

[0013] As is well known, silica is a compound that is very suitable for use as a catalytic support, but it cannot be extruded in a traditional extrusion device like other materials, so that a product that is durable enough in the process cannot be obtained. This is because, from its manufacture to its use, the catalyst needs to go through many steps, and these steps may affect its physical integrity. It must especially be able to withstand crushing, abrasion, and pressure changes related to the operating conditions of the catalytic reactor in which it is used. Therefore, there has always been a need for high-performance catalysts with improved mechanical and physical properties. Summary of the Invention Surprisingly, the applicant has found that a special preparation method, which employs a hydrothermal treatment in the presence of steam, especially on a support based on SiO2-based high-temperature resistant oxides and KL zeolite, and then impregnation with Group VIII metals, can obtain an aromatization catalyst with improved catalytic performance and good mechanical strength. In addition, the method of the present invention also has the advantage of being more environmentally friendly, avoiding water-consuming washing operations and the use of harmful halides.

[0015] The present invention relates to a method for preparing an aromatization catalyst, which catalyst comprises at least 70% by weight of KL zeolite, SiO2-based high-temperature resistant oxides, and Group VIIIB metals, and the method comprises at least the following steps: a) Optionally in the presence of an organic auxiliary, mixing at least one source of KL zeolite of structural type LTL and at least one source of SiO2 with at least one solvent selected from water, physical solvents, and chemical solvents to obtain a mixture; b) Shaping the mixture obtained at the end of step a), preferably by extrusion; c) Optionally aging the shaped material in air at a temperature of 0 to 70 °C, preferably in humid air with a relative humidity of 20% to 100%, for a time of 1 minute to 72 hours; d) Optionally drying the shaped and optionally aged material at a temperature of 0 to 200 °C for a time of 1 minute to 72 hours, and optionally subsequently calcining at a temperature of 200 to 600 °C, preferably at a temperature of 250 to 450 °C, for d') 1 to 12 hours, and preferably for a time of 1 to 4 hours; e) A step of hydrothermally treating the material formed in step b), optionally aged in step c), and optionally dried / calcined in step d) in the presence of steam at a temperature of 200 to 550 °C, preferably at atmospheric pressure, for a time of 30 minutes to 5 hours to obtain a catalyst support; f) An optional step of calcining the support obtained at the end of step e) at a temperature of 200 to 680 °C, preferably 400 to 660 °C, for a time of 1 to 12 hours, and preferably 1 to 4 hours to obtain a calcined catalyst support; g) A step of impregnating with a Group VIII metal (preferably platinum) by contacting the support obtained at the end of step e) or f) with a solution of the precursor of the metal dissolved in an aqueous phase, such that the metal content on the catalyst is 0.1 wt% to 10 wt%, preferably 0.2 wt% to 5 wt%, preferably 0.3 wt% to 2 wt%, and very preferably 0.5 wt% to 1.2 wt% based on the total mass of the anhydrous catalyst; h) A step of drying the impregnated material obtained at the end of step g), preferably at a temperature of 50 °C to 200 °C; i) A step of calcining the dried material obtained at the end of step h) in a stream of pure air or air diluted with a neutral gas at 200 °C to 500 °C, preferably at 250 °C to 450 °C, and very preferably at 350 °C to 420 °C to obtain a calcined catalyst.

[0016] The preparation method may include: j) A step of reducing the calcined catalyst obtained at the end of step i) by contacting the catalyst with a hydrogen-containing gas stream (pure or diluted with a neutral gas) at a temperature of 300 °C to 550 °C, preferably 350 °C to 500 °C, and very preferably 450 °C to 500 °C before contacting with the raw materials.

[0017] Step a) may be carried out by mixing at room temperature for a time of 5 to 60 minutes, and preferably 10 to 50 minutes.

[0018] KL zeolite and SiO2 silica may be introduced into step a) in the form of an oxide mixture in the following proportions: - 70% to 90% by weight, preferably 70% to 85% by weight of at least one KL zeolite, and - 10% to 30% by weight, preferably 15% to 30% by weight of at least one SiO2 silica source, And the mixture may be mixed with the following: - 10% to 30% by weight of a solvent based on the total weight of the oxide mixture, and - From 0% to 20% by weight, preferably from 1% to 15% by weight, more preferably from 1% to 10% by weight, and very preferably from 1% to 7% by weight, based on the total weight of the oxide mixture, of at least one organic auxiliary agent The sum of the amounts of the respective compounds introduced in this step is 100%.

[0019] In step a), a single silica source can be used, preferably precipitated silica or silica gel, and very preferably precipitated silica.

[0020] In step a), two different silica sources can be used, which are preferably precipitated silica and colloidal silica sol.

[0021] The particle size or granularity of the silica used in step a) can be less than 100 μm, preferably less than 80 μm, more preferably less than 60 μm, even more preferably less than 20 μm or actually less than 10 μm for precipitated silica or silica gel, and 5 to 200 nm, preferably 15 to 50 nm for colloidal silica sol.

[0022] The organic auxiliary agent can be selected from cellulose derivatives, polyethylene glycol, aliphatic monocarboxylic acids, alkyl aromatic compounds, sulfonates, fatty acids, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide polymers, scleroglucan, hydroxyethylcellulose derivatives, carboxymethylcellulose (such as Methocel TM ), lignosulfonates and galactomannan derivatives, used alone or in combination, and preferably carboxymethylcellulose.

[0023] The specific surface area of the carrier obtained at the end of step e) or f) can be 80 to 200 m 2 / g, the total pore volume is 0.35 to 0.6 cm 3 / g, the macropore volume is 0.08 to 0.16 cm 3 / g, the mesopore volume is 0.2 cm 3 / g to 0.4 cm 3 / g, and the micropore volume is less than 0.07 cm 3 / g, the sodium content is less than 0.2% by weight, and the mechanical strength measured by the single-grain crushing test (hereinafter referred to as SPC) is at least greater than or equal to 0.5 daN / mm, and preferably at least greater than or equal to 0.6 daN / mm, and preferably at least greater than or equal to 0.7 daN / mm.

[0024] The present invention also relates to an aromatization catalyst support in the form of a composite KL zeolite - SiO₂ material containing at least 70% of KL zeolite obtained in step e) or f) of the method according to any of the above variants, having a specific surface area of 80 to 200 m 2 / g, a total pore volume of 0.35 to 0.6 cm 3 / g, a macropore volume of 0.08 to 0.16 cm 3 / g, a mesopore volume of 0.2 cm 3 / g to 0.4 cm 3 / g, and a micropore volume of less than 0.07 cm 3 / g, a sodium content of less than 0.2% by weight, and a mechanical strength measured by a single - grain crushing test (hereinafter referred to as SPC) of at least greater than or equal to 0.5 daN / mm, and preferably at least greater than or equal to 0.6 daN / mm, and more preferably at least greater than or equal to 0.7 daN / mm.

[0025] The present invention also relates to a catalyst for aromatizing a C6 - C8 paraffin fraction, which catalyst can be prepared by the method according to any of the above variants, and contains at least 70% by weight of KL zeolite of structural type LTL with an Si / Al ratio of 2.8 to 4, preferably 2.8 to 3.5, 10% to 30% by weight of a high - temperature - resistant oxide of SiO₂ type, a Group VIIIB metal, preferably platinum. The catalyst also has a specific surface area of 80 to 200 m 2 / g, a micropore volume of less than 0.04 cm 3 / g, a Group VIIIB metal content of 0.1% to 10% by weight, preferably 0.2% to 5% by weight, and very preferably 0.3% to 2% by weight, and even more preferably 0.5% to 1.2% by weight of the metal, and a dispersion of 50% to 70% of the metal.

[0026] The metal can be platinum, and the platinum content can be 0.6% to 1.0% by weight relative to the total weight of the catalyst.

[0027] The KL zeolite content of the catalyst can be 70% to 85% by weight, and the high - temperature - resistant oxide content of the catalyst can be 15% to 30% by weight, and the sum of the total components of the catalyst including the metal is 100%.

[0028] Finally, the present invention relates to a process for aromatizing at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising a C6-C8 paraffinic fraction, the process being carried out by contacting a catalyst prepared according to any of said variants or a catalyst according to any of said variants with the gaseous feedstock to be treated in the presence of hydrogen, said process being carried out in the liquid phase or the gas phase at a temperature of 400 °C to 550 °C, at a pressure of 2 to 20 Mpa, at a molar ratio of hydrogen to hydrocarbon compounds of 1 to 10, and at a weight hourly space velocity WHSV of 1 to 10 h -1 -1.

[0029] The aromatization process can exhibit a conversion of n-paraffin and iso-paraffin to C6-C7 of greater than or equal to 85% and an aromatic yield of greater than or equal to 80%.

[0030] Description of embodiments The present invention will be described in detail below by means of non-limiting embodiments and examples.

[0031] In addition, specific and / or preferred embodiments of the present invention can also be described. They can be implemented alone or in combination, and as long as it is technically feasible, there is no limitation on the combination.

[0032] Definition Unless otherwise stated, mass percentages are expressed relative to the anhydrous mass of the final composite material (support or catalyst). This anhydrous mass is determined by a measurement called loss on ignition (LOI), which corresponds to the mass change resulting from heating the sample at 1000 °C for 2 hours. The loss on ignition is expressed as a mass percentage of the solid.

[0033] In the following part of this text, "side crush strength" should be understood to refer to the mechanical strength of the material (support or catalyst) according to the present invention determined by the single particle crush (SPC) test. This is a standardized test (standard ASTM D4179-01), which involves subjecting a material in the form of millimeter-sized objects (such as beads, pellets or extrudates) to a compressive force that causes fracture. Therefore, this test is a measurement of the tensile strength of the material. The analysis is repeated on a certain number of individually sampled solids (and usually a solid number of 10 to 200). The average value of the measured fracture side force constitutes the average SPC, which is expressed in units of force (N) in the case of particles; and in the case of extrudates, it is expressed in units of force per unit length (daN / mm).

[0034] In the following part of this text, the specific surface area should be understood as the BET specific surface area (SBET) determined by nitrogen adsorption, which is measured according to the standard ASTM D3663-78 established based on the Brunauer-Emmett-Teller method described in Journal of the American Chemical Society, 60, 309 (1938).

[0035] The term "macropore" refers to pores with a pore diameter greater than 50 nm.

[0036] The term "mesopore" refers to pores with a pore diameter between 2 nm and 50 nm (including the boundary values).

[0037] The term "micropore" refers to pores with a pore diameter less than 2 nm.

[0038] According to the present invention, the "total pore volume" (TPV) of a material, support or catalyst should be understood as the volume measured by mercury intrusion porosimetry according to standard ASTM D4284-83, using a surface tension of 484 dyn / cm and a contact angle of 140° at a maximum pressure of 4000 bar (400 MPa). The wetting angle is taken to be equal to 140°, in accordance with the recommendations in the work "Techniques de l'ingénieur, traité analyse et caractérisation" by Jean Charpin and Bernard Rasneur, pages 1050-1055 of [Techniques of the Engineer, Analysis and Characterization Treatise].

[0039] For better accuracy, the value of the total pore volume corresponds to the total pore volume value measured on the sample by mercury intrusion porosimetry minus the total pore volume value measured on the same sample at a pressure corresponding to 30 psi (about 0.2 MPa) by mercury intrusion porosimetry.

[0040] The volumes of macropores and mesopores are measured by mercury intrusion porosimetry according to standard ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyn / cm and a contact angle of 140°. The value of completely filling the interparticle voids with mercury is set at 0.2 MPa, and above this value, it is considered that mercury has penetrated into the pores of the sample.

[0041] According to the present invention, the macropore volume of a material, support or catalyst is defined as the cumulative volume of mercury introduced at a pressure between 0.2 MPa and 30 MPa, corresponding to the volume contained in pores with an apparent diameter greater than 50 nm.

[0042] According to the present invention, the mesopore volume of the material, support or catalyst is defined as the cumulative volume of mercury introduced at a pressure of 30 MPa to 400 MPa, corresponding to the volume contained in pores with an apparent diameter of 2 to 50 nm.

[0043] According to the present invention, the macropore median diameter (Dmacro, in nm) of the material, support or catalyst is defined as the diameter such that, as measured by mercury porosimetry, the pores with all sizes smaller than this diameter account for 50% of the macropore volume.

[0044] According to the present invention, the median mesopore diameter (Dmeso, in nm) of the material, support or catalyst is defined as the diameter such that, as measured by mercury porosimetry, the pores with all sizes smaller than this diameter account for 50% of the mesopore volume.

[0045] The micropore volume of the material, support or catalyst is degassed under vacuum (P < 6.7×10 -4 Pa), and then maintained at a temperature of 200 to 650 °C for 9 to 16 hours, preferably for 10 hours at 500 °C. Preferably, it is calculated from the nitrogen adsorption isotherm at 77 Kelvin (77 K) by the t-curve method. Then, the nitrogen adsorption isotherm measurement at 77 Kelvin (77 K) is performed on an ASAP 2020 M instrument from Micromeritics, taking at least 35 measurement points at a relative pressure where the P / P0 ratio ranges from 0.002 to 1. The micropore volume is determined from the isotherm obtained by the t-curve method, applying standard ISO 15901-3:2007 and calculating the statistical thickness t through the Harkins-Jura equation. The micropore volume is obtained by performing a linear regression on the points on the t-curve with respect to the ordinate from the origin and the slope of the linear regression. The evaluated micropore volume is expressed in cm 3 of liquid adsorbate per g of anhydrous adsorbent.

[0046] The micropore volume may also be able to verify the percentage of KL zeolite present in each step of the method for preparing the catalyst according to the present invention, which contains at least 70% by mass of KL zeolite at the end of the method. The micropore volume of pure KL zeolite is considered to be 0.140 cm 3 / g. A micropore volume less than 0.140 cm 3 / g indicates the presence of amorphous material without micropores in the material, or that the micropores of the zeolite may be partially blocked. If the micropores of the zeolite are not partially blocked, the value of the micropore volume is proportional to the amount of KL zeolite present in the mixture. For example, a micropore volume of 0.070 cm 3 / g indicates that the mixture contains 50% of KL zeolite.

[0047] The molar amounts of the various elements present in the material can be determined by X-ray fluorescence. This method can in particular determine the Si / Al ratio of the microporous zeolite material. For pure KL zeolite or high-purity KL zeolite, the Si / Al ratio is usually between 2.8 and 4.3 (excluding the upper limit value).

[0048] X-ray fluorescence (XRF) spectrometry is a chemical analysis technique that uses the physical property of the material - X-ray fluorescence. This technique can analyze most chemical elements starting from beryllium (Be), with a concentration range extending from a few ppm to 100%, and obtain accurate and reproducible results. X-rays are used to excite the atoms in the sample, causing them to emit X-rays with energy characteristics of each element present. Subsequently, the intensity and energy of these X-rays are measured to determine the concentration of elements in the catalyst, and in particular the content of Pt and Cl.

[0049] The H2O2 titration method is a dynamic chemisorption measurement technique that reveals the dispersion state of the metal (especially platinum Pt) on the catalyst after the catalyst is reduced.

[0050] The solid is placed in an equilibrium state in a stream of carrier gas (helium), which contains a small amount of "probe" gas and is fed in a pulsed manner. Each pulse contains a known amount of adsorbate. The amount adsorbed by the solid is measured as the difference in the proportion of the "probe" gas at the inlet and outlet of the reactor.

[0051] The analytical instrument used for dynamic chemisorption is the Xorb tool from GIRA (T135).

[0052] For the titration measurement of about 2 g of the sample, after the first step of calcination in air at 400 °C for 2 hours, and then reduction in hydrogen at 470 °C for 2 hours. After returning to room temperature, the first series of O2 pulses is carried out, and the first volume (V1) of oxygen chemisorbed on the catalyst metal (especially platinum) is measured; then, after reduction at room temperature for 1 hour, the second series of O2 pulses is carried out, and the second volume (V2) of oxygen chemisorbed on the catalyst metal (especially platinum) is measured.

[0053] Assuming that all metal atoms (such as platinum atoms) are accessible, the theoretical volume of oxygen consumed is calculated as follows: Math 1 Then the dispersion of the metal (such as platinum) is obtained according to the following formula: Math 2 In this article: The term "support" refers to a shaped material composed of KL zeolite (a) and a silica-based high-temperature resistant oxide (b), preferably formed by mixing / extrusion molding.

[0054] The term "catalyst" refers to the previously defined support, to which a Group VIIIB metal (c), such as platinum, is added.

[0055] Within the meaning of the present invention, the different embodiments proposed can be used alone or in combination with each other, without any limitation on the combination.

[0056] For the purposes of the present invention, the various parameter ranges of a given step, such as a pressure range and a temperature range, can be used alone or in combination. For example, for the purposes of the present invention, a preferred pressure value range can be used in combination with a more preferred temperature value range.

[0057] The object of the present invention is to provide a catalyst suitable for the aromatization of C6 / C8 or C6 / C7 hydrocarbon fractions, which particularly comprises: (a) KL zeolite (structural type LTL), the Si / Al molar ratio of which is advantageously from 2.8 to 4, preferably from 2.8 to 3.5, and very preferably 3, (b) A silica-based high-temperature resistant oxide, (c) A Group VIIIB metal.

[0058] Surprisingly, the applicant has found that a catalyst preparation method, starting from a mixture of KL zeolite in the presence of at least one synthetic silica source with a low sodium content, using a hydrothermal heat treatment in the presence of steam (commonly known as "steaming"), after adding platinum to the catalyst, shows improved performance in the aromatization of C6 / C8, especially C6 / C7 fractions, compared to the catalysts of the prior art, and has different structural characteristics, while ensuring high mechanical strength.

[0059] Therefore, the catalyst according to the present invention is in the form of an active phase based on KL zeolite, to which a silica-based high-temperature resistant oxide of SiO2, which will act as a binder, is added to form the support, and finally a Group VIIIB metal, such as platinum, is added to form the catalyst (regardless of the order and manner of introduction of these different compounds).

[0060] Preferably, the content of the high-temperature resistant oxide (b) in the form of silicon oxide is from 10% to 30% by weight of the support, and very preferably from 15% to 30% by weight of the support.

[0061] Preferably, the S_BET specific surface area of the support is at least 80 m 2 / g, preferably between 120 and 200 m 2between / g. The catalyst support with such a specific surface area especially has good catalytic activity.

[0062] The content of KL zeolite (a) in the catalyst is preferably selected to be at least 70% by weight, especially 70% to 85% by weight, based on the total weight of the catalyst.

[0063] The content of the high-temperature resistant oxide of SiO2 in the catalyst is 10% to 30% by weight, preferably 15% to 30% by weight, based on the total weight of the catalyst.

[0064] Preferably, the Group VIIIB metal (c) can be a platinum group element, especially Pt or Pd, preferably Pt. Preferably, the content of the Group VIII metal (c) can be 0.1% to 10% by weight, preferably 0.2% to 5% by weight, very preferably 0.3% to 2% by weight, and even more preferably 0.5% to 1.2% by weight, very advantageously 0.6% to 1.0% by weight, based on the total weight of the catalyst. In a very preferred embodiment, the catalyst can contain 0.6% to 1.0% by weight of platinum based on the total weight of the catalyst.

[0065] The sum of the weight percentages of the components of the catalyst is 100%.

[0066] Another subject of the present invention is a method for preparing the above-mentioned catalyst, which comprises the following steps: - Mixing KL zeolite with at least one high-temperature resistant oxide of silica, - Shaping the obtained mixture, for example, by extrusion, - Optionally aging, optionally drying or optionally calcining the shaped mixture in the previous step, - Hydrothermally treating the shaped material in the previous step in the presence of steam to obtain a support, - Optionally calcining the support obtained in the previous step, - Impregnating the support with a precursor of the Group VIIIB metal, - Drying and calcining the impregnated support to obtain the catalyst.

[0067] Another subject of the present invention is the use of the above-mentioned catalyst in a method for aromatizing a hydrocarbon feedstock containing a C6-C8 paraffin fraction (hydrocarbon chains containing 6 to 8 carbon atoms).

[0068] Another subject of the present invention is a method for aromatizing at least one alkane or cycloalkane contained in a C6-C8 hydrocarbon feedstock, so that the method is carried out in the liquid phase or gas phase, at a temperature of 400°C to 550°C, at a pressure of 2 to 20 MPa, at a molar ratio of hydrogen to hydrocarbon compound of 1 to 10, and for 1 to 10 h -1operate at a weight hourly space velocity (WHSV) and use a catalyst according to any of the variants, in particular a catalyst in oxide form, which comprises (a) KL zeolite (structure type LTL) having a Si / Al molar ratio of from 2.8 to 4, preferably from 2.8 to 3.5, more preferably 3, (b) a silica-based refractory oxide, (c) a Group VIIIB metal.

[0069] Schematically and according to the invention, the method for preparing the catalyst comprises at least the following steps: a) a step of mixing at least one source of KL zeolite (structure type LTL) and at least one source of silica in at least one solvent to obtain a mixture, the mixing being carried out in particular in the form of a mixture of zeolite powder and silica powder and / or a mixture of zeolite powder and silica sol in such proportions that the zeolite content of the final material is at least 70%, and / or in the form of a mixture of zeolite powder, silica powder and silica sol in such proportions that the zeolite content of the final material is at least 70%. Any combination of KL zeolite and at least one silica source in the starting mixture can be used in such a way that the proportion requirements of KL zeolite and silica refractory oxide in the catalyst according to the invention are met. The silica source preferably has a low sodium content, advantageously less than 1000 ppm.

[0070] b) a step of shaping the mixture obtained at the end of step a), c) an optional step of ageing the shaped material obtained at the end of step b) d) an optional drying step e) a step of hydrothermally treating the shaped material (optionally aged in step c) and optionally dried / calcined in step d)) in the presence of steam, f) an optional step of calcining the material obtained at the end of step e) to obtain a calcined support g) a step of impregnating with a Group VIII metal by contacting the support obtained at the end of step e) or f) with a solution obtained by dissolving a metal precursor in an aqueous phase h) a step of drying the impregnated support obtained at the end of step g) i) a step of calcining the impregnated support obtained at the end of step h) to obtain a catalyst j) a step of reducing the catalyst obtained at the end of step i), which step can be carried out before the catalyst is used in a catalytic process.

[0071] The preparation method and its individual steps are described in detail below.

[0072] Mixing step a) According to the present invention, in step a), at least one KL zeolite source and at least one silica source are mixed with at least one solvent (such as water) to obtain a moldable mixture.

[0073] The silica source can be selected from all silica sources known to those skilled in the art, either alone or as a mixture thereof - such as precipitated silica powder, silica gel, and colloidal silica sol.

[0074] Preferably, and without limitation, one or more precipitated silica powders or silica gels are preferably selected from low-sodium silica (Na < 1000 ppm), especially from the following commercial sources: Nyasil 20 (Nyacol®), Siliaflash P60 (Silicycle®), Siliaflash C60 (Silicycle®), Ultrasil VN3 GR (Evonik®).

[0075] Preferably, and without limitation, the colloidal silica sol is selected from the following commercial sources: Ludox (W. R. Grace Davison®), Nyacol (Nyacol Nano Technologies®, Inc. or PQ Corp®), Nalco (Nalco Chemical Company®), Ultra-Sol (RESI Inc®), NexSil (Nyacol Nano Technologies®, Inc. or PQ Corp®).

[0076] Most colloidal silica sols are made from sodium silicate and inevitably contain sodium. Since the presence of sodium may have an adverse effect on catalytic activity, an ion exchange step may be required to reduce or even eliminate the residual sodium. To avoid this step, a colloidal silica sol with a low sodium content is preferably used, especially a silica sol stabilized with ammonium counterions - for example, they include Ludox AS40 stabilized with ammonium counterions, or Nalco 1034A, Ultra-Sol 7H, or NexSil 20A.

[0077] The one or more silica sources used in the method according to the present invention are advantageously amorphous synthetic silica rather than natural silica that may have excessive impurities.

[0078] Preferably, at least one organic auxiliary can also be incorporated during step a).

[0079] The organic auxiliary agent may also be selected from all additives known to those skilled in the art.

[0080] In the case where at least one organic auxiliary agent is added in step a), the organic auxiliary agent may advantageously be selected from cellulose derivatives, polyethylene glycols, aliphatic monocarboxylic acids, alkylated aromatic compounds, sulfonates, fatty acids, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide polymers (such as xanthan gum), scleroglucan, hydroxyethylcellulose derivatives, carboxymethylcellulose (such as Methocel TM ), lignosulfonates and galactomannan derivatives, used alone or as a mixture; the organic auxiliary agent is preferably carboxymethylcellulose.

[0081] Preferably, the organic auxiliary agent can be mixed in the form of a powder or in the form of a solution in the solvent.

[0082] The solvent may advantageously be selected from water, physical solvents and chemical solvents, especially ethanol, alcohols and amines. Preferably the solvent is water.

[0083] In the context of the present invention, it is entirely possible to consider preparing a mixture of two or more different silica powders and / or different silica sols.

[0084] The mixing order of at least the silica source, the KL zeolite source and optionally at least one organic auxiliary agent powder, when they are mixed in powder form, with at least one solvent is not important.

[0085] The mixing of the powder and the solvent can advantageously be carried out simultaneously.

[0086] The addition of the powder and the solvent can also advantageously be carried out alternately.

[0087] The solvent is added to the powder mixture or the mixture of powder and sol in an amount such that the mixture can be shaped, for example by extrusion molding. The amount of the solvent introduced can particularly be 30% to 40% of the total mass of the oxide mixture (KL zeolite and silica).

[0088] The particle size or granularity of the silica introduced in the form of precipitated silica or silica gel in step a) is preferably less than 100 μm, very preferably less than 80 μm, more preferably less than 60 μm, even more preferably less than 20 μm, or actually less than 10 μm. The particle size or granularity of colloidal silica is preferably 5 to 200 nm, preferably 15 to 50 nm.

[0089] Preferably, the mixing step a) is carried out by batch or continuous kneading.

[0090] In the case where step a) is carried out in batches, step a) is advantageously carried out in a kneader, preferably equipped with a Z-shaped arm, a cam mixer or any other type of mixer (such as a planetary mixer). The mixing step a) can obtain a homogeneous mixture of the powdery components.

[0091] Preferably, step a) is carried out by mixing for 5 to 60 minutes, and preferably 10 to 50 minutes, at room temperature. The rotational speed of the kneader arm is advantageously 10 to 75 revolutions per minute, preferably 25 to 50 revolutions per minute.

[0092] Preferably, in the mixing step a) of the process according to the invention, KL zeolite and silica are introduced in the following proportions: - 70% to 90% by weight, very preferably 70% to 85% by weight, of at least one KL zeolite (Si / Al ratio from 2.8 to 4.3, excluding the upper limit value), - 10% to 30% by weight of silica in the form of SiO2 oxide, provided by one or more silica sources; Relative to the total amount of oxides (KL zeolite and silica) introduced, the powder mixture is mixed with the following substances: - 30% to 40% by weight of a solvent - 0% to 20% by weight, preferably 1% to 15% by weight, preferably 1% to 10% by weight, and very preferably 1% to 7% by weight of at least one organic auxiliary agent to be added to the mixture, - The weight percentages are expressed relative to the total weight of the anhydrous materials, and the sum of the amounts of each compound in the mixture is 100%.

[0093] Shaping step b) According to the invention, step b) requires shaping the mixture obtained at the end of step a). The shaping can be carried out by any technique known to those skilled in the art, in particular extrusion, granulation, spheronization, pelletization, etc.

[0094] The mixture at the end of step a) can preferably be shaped by extrusion.

[0095] When shaping the mixture obtained from step a) by extrusion, step b) can advantageously be carried out in a single-screw or twin-screw piston extruder.

[0096] In this case, an organic auxiliary agent can be optionally added in the mixing step a). The presence of the organic auxiliary agent facilitates shaping by extrusion. The optional organic auxiliary agent is as described above and is introduced in step a) in the above proportions.

[0097] In the case where the preparation method is carried out continuously, the mixing step a) can be carried out in combination with the step b) of forming a shape by extrusion in the same equipment. According to this embodiment, the extrusion of the mixture (also referred to as "kneaded paste") can be carried out, for example, by direct extrusion at the end of a twin-screw continuous kneader or by connecting one or more batch kneaders to an extruder. The geometry of the die for shaping the extrudate can be selected from dies well known to those skilled in the art. Thus, they can be, for example, cylindrical, multi-lobed, grooved or slotted.

[0098] When the mixture obtained by the extrusion forming step a), the amount of solvent added in the mixing step a) is adjusted so that, at the end of this step and regardless of the variant used, a mixture or paste that is neither flowing nor too dry is obtained, thus allowing it to be extruded under suitable pressure conditions known to those skilled in the art and depending on the extrusion equipment used.

[0099] Preferably, the step b) of forming a shape by extrusion is carried out at an extrusion pressure greater than 1 MPa, and preferably from 3 MPa to 10 MPa.

[0100] The loss on ignition of the material obtained after the shaping step (advantageously in the form of an extrudate, sheet or bead) is from 30% to 40% by weight.

[0101] Aging step c) (optional) The method for preparing the material according to the invention may include an optional aging step c) of the shaped material obtained at the end of step b). In its implementation, the aging step is advantageously carried out at a temperature of 0 °C to 70 °C, preferably 10 °C to 60 °C, and preferably 20 to 50 °C for a time of 1 minute to 72 hours, preferably 30 minutes to 72 hours, preferably 1 hour to 48 hours, and more preferably 1 to 24 hours.

[0102] Preferably, the aging step is carried out in air and preferably in humid air with a relative humidity of 20% to 100%, and preferably 70% to 100%. This step achieves good hydration of the material, which is necessary to limit the appearance of cracks, as cracks have an adverse effect on mechanical strength.

[0103] After this step, the loss on ignition of the shaped and aged material is advantageously from 15% to 25% by weight.

[0104] Drying step d) (optional) The method for preparing the material according to the present invention may include a drying step d) for the shaped material obtained at the end of step b) or at the end of step c) (if this step is carried out). The drying step is advantageously carried out at a temperature of from 0 to 200 °C, preferably from 50 to 150 °C, and preferably from 70 to 150 °C for a time of from 1 minute to 72 hours, preferably from 30 minutes to 72 hours, preferably from 1 hour to 48 hours, and more preferably from 1 to 24 hours.

[0105] The loss on ignition of the dried material obtained in this step is advantageously from 7% to 10% by weight.

[0106] Optional calcination step d') Advantageously, the material shaped and obtained from the ageing step c) or the drying step d) may also optionally be subjected to a calcination step d'), which is carried out at a temperature of from 200 to 600 °C, preferably from 250 to 450 °C, for a time of from 1 to 12 hours, and preferably from 1 to 4 hours. This calcination step is particularly advantageous for eliminating the organic auxiliaries used, thus facilitating the shaping of the material.

[0107] The optional calcination step d') is advantageously carried out in an oxygen-containing stream; for example, it is preferred to calcine the extrudate in dry air or air of different humidities, or to carry out a heat treatment in the presence of a gas mixture comprising an inert gas (preferably nitrogen) and oxygen. The gas mixture used preferably comprises at least 5% by volume, or even preferably at least 10% by volume, of oxygen. The calcination step d') may include a gradual increase in temperature and optionally a temperature plateau at a temperature of from 100 to 200 °C.

[0108] Hydrothermal treatment step e) The preparation method according to the present invention includes a hydrothermal treatment step e) of the material obtained from step b), c), d) or d') in the presence of steam.

[0109] The material shaped in step b), optionally aged in step c) and optionally dried / calcined in step d) is subjected to hydrothermal treatment in the presence of steam at a temperature of from 200 to 550 °C.

[0110] The hydrothermal treatment is carried out by any technique known to those skilled in the art. The term "hydrothermal treatment" means bringing the mixed support into contact with water in the gas phase or the liquid phase at any step in the production. The term "hydrothermal treatment" may in particular mean steam treatment, steaming, autoclaving, calcination in moist air or rehydration. Without any limitation of the scope of the present invention, the effect of such treatment is in particular to make the silica component mobile.

[0111] In one embodiment, the hydrothermal treatment step e) can be carried out at atmospheric pressure at a temperature of 200 °C to 550 °C, more preferably for a time of 30 minutes to 5 hours. According to the present invention, hydrothermal treatment is a treatment comprising steam and gas at a certain temperature. The gas is advantageously air or nitrogen. The volume composition of water in the gas can be 20% to 100%, preferably 30% to 90%, more preferably 40% to 70%.

[0112] The loss on ignition of the support obtained after this step is advantageously 15% to 20% by weight.

[0113] In a preferred embodiment, the hydrothermal treatment step e) can replace all or part of the calcination step d') or f).

[0114] Optional calcination step f) Advantageously, the shaped material obtained from the hydrothermal treatment step e) can also optionally be subjected to a calcination step f), which is carried out at a temperature of 200 to 680 °C, preferably 400 to 660 °C, for a period of 1 to 12 hours, and preferably 1 to 4 hours, in one or more sequences. This calcination step can be particularly suitable for removing the chemically adsorbed water remaining in the zeolite micropores.

[0115] The optional calcination step f) is advantageously carried out in an oxygen-containing stream; for example, it is preferred to calcine the extrudate in dry air or air of different humidities, or to carry out a heat treatment in the presence of a gas mixture comprising an inert gas (preferably nitrogen) and oxygen. The gas mixture used preferably contains at least 5% by volume, and in fact even preferably at least 10% by volume, of oxygen.

[0116] The loss on ignition of the extrudate obtained after this step is advantageously 1% to 10% by weight.

[0117] At the end of steps a) to e) or a) to f) of the preparation method according to the present invention, the resulting material (hereinafter referred to as "support") is in the form of an extrudate or granule or sheet or bead.

[0118] However, it is not excluded that the resulting material is subsequently introduced into, for example, a device that allows its surface to be rounded, such as a pan or any other device that allows the material to be rounded.

[0119] The catalyst support according to the present invention is composed of a composite KL zeolite - SiO2 material and has a specific surface area of 80 to 200 m 2 / g.

[0120] The catalyst support according to the present invention has a total pore volume of 0.35 to 0.6 cm 3 / g.

[0121] The catalyst support according to the present invention has a macropore volume of 0.08 to 0.16 cm 3 / g.

[0122] The catalyst support according to the present invention has a mesopore volume of 0.2 cm 3 / g to 0.4 cm 3 / g.

[0123] The catalyst support according to the present invention has a micropore volume of less than 0.07 cm 3 / g, and preferably greater than 0.03 cm 3 / g.

[0124] The catalyst support according to the present invention has a sodium content of less than 0.2 wt%.

[0125] The catalyst support according to the present invention exhibits fully satisfactory mechanical properties, especially in terms of mechanical strength.

[0126] Specifically, the catalyst support according to the present invention has a mechanical strength measured by a single pellet crushing test (hereinafter referred to as SPC) of at least greater than or equal to 0.5 daN / mm, and preferably at least greater than or equal to 0.6 daN / mm, and preferably at least greater than or equal to 0.7 daN / mm.

[0127] The improvement in mechanical strength allows the use of the catalyst support in processes in the presence of water or solvents and at relatively high temperatures to be considered.

[0128] Steps g), h) and i) allow the catalyst according to the present invention to be obtained from the support obtained in step e) or f).

[0129] Step g): Impregnation step The catalyst support according to the present invention is impregnated by adding a Group VIII metal (preferably a noble metal of the Pt type). The impregnation is achieved by contacting the support with an impregnation solution of the metal precursor.

[0130] The platinum precursor used is preferably selected from the following precursors, but is not limited to the following list: hexachloroplatinic acid (H2PtCl6), bromoplatinic acid, ammonium chloroplatinate, platinum chloride, dichlorodicarbonyl platinum dichloride, tetraammineplatinum dichloride (Pt(NH3)4Cl2), tetraammineplatinum dinitrate Pt(NH3)4(NO3)2 or dihydroxydiammineplatinum. Organoplatinum complexes such as platinum(II) acetylacetonate can also be used.

[0131] The precursor is diluted in the aqueous phase to form an impregnation solution.

[0132] The metal can be introduced onto the support by various techniques known to those skilled in the art, such as dry impregnation, incipient wetness impregnation, in the form of a fluidized bed, by pore filling impregnation, etc., preferably dry impregnation or incipient wetness impregnation. This step is carried out to obtain an excellent distribution and dispersion of the metal phase.

[0133] The amount of Group VIII metal introduced in step g) of the preparation method according to the invention is preferably as follows: 0.1% to 10% by weight, preferably 0.2% to 5% by weight, preferably 0.3% to 2% by weight, and very preferably 0.5% to 1.2% by weight, and even more preferably 0.6% to 1.0% by weight of metal, preferably platinum, measured as a mass percentage relative to the total mass of the final catalyst.

[0134] Drying step h) The material thus obtained in step g) is subjected to a drying step to remove residual water in the pores. This step can be carried out in a moving bed, a swept bed, a static system, etc. The temperature used in this step is preferably from 50 °C to 200 °C, preferably from 60 °C to 150 °C, and very preferably from 80 °C to 120 °C.

[0135] Calcination step i) The material thus obtained in step h) is subjected to a calcination step required for the decomposition of the metal precursor and the effective distribution and dispersion of the metal phase. This step is carried out in a stream of air or air diluted with a neutral gas (N2, Ar, etc.). This step can preferably be carried out in a pure air stream. The temperature used in this step can preferably be from 200 °C to 500 °C, preferably from 250 °C to 450 °C, and very preferably from 350 °C to 420 °C. Step i) can include a gradual increase in temperature and optionally a plateau at a temperature of 100 to 200 °C.

[0136] Catalyst reduction step j) The material thus obtained in step i) can be subjected to a reduction step required for the activation of the metal precursor. This step is preferably carried out before contact with the feedstock and can be carried out before charging or in situ in a stream of pure hydrogen or hydrogen diluted with a neutral gas (N2, Ar, etc.). The temperature used in this step is preferably from 300 °C to 550 °C, preferably from 350 °C to 500 °C, and very preferably from 450 °C to 500 °C.

[0137] At the end of step i) or j), the catalyst according to the invention has a specific surface area of 80 to 200 m 2 / g and a micropore volume of less than or equal to 0.04 cm 3 / g, more particularly 0.015 to 0.04 cm 3 / g.

[0138] At the end of the preparation process according to the present invention, the Cl content of the catalyst is advantageously less than 0.5%, and the Na content is less than 0.2%, without any washing operation being required.

[0139] The catalyst according to the present invention has a metal content (preferably the content of platinum) of 0.1% to 10% by weight, preferably 0.2% to 5% by weight, very preferably 0.3% to 2% by weight, more preferably 0.5% to 1.2% by weight, and very advantageously 0.6% to 1.0% by weight of the anhydrous catalyst.

[0140] The catalyst according to the present invention exhibits a metal dispersion of 50% to 70%, especially the dispersion of platinum.

[0141] The catalyst obtained by applying a Group VIII metal (preferably platinum) to a support by impregnation is contacted in a reactor with the gaseous feedstock to be treated, and the reactor can be a fixed-bed reactor or a radial reactor.

[0142] The catalyst obtained at the end of the preparation process according to the present invention can be used in catalytic applications, especially the aromatization of C6 / C8 alkane fractions.

[0143] Such catalysts have particularly proven to exhibit improved activity and aromatic hydrocarbon yields in the aromatization reaction of C6-C8, and especially C6-C7 fractions, compared to the catalysts known to those skilled in the art. In addition, since no halides are used and the additional washing step is omitted, the method for preparing the catalyst according to the present invention also has the advantage of reducing the environmental impact of catalyst preparation.

[0144] The present invention is illustrated by the following examples, which do not limit the present invention in any way. Examples

[0145] Example 1: Preparation of Catalyst A Pt / KL-SiO2 (Comparative) Support A was prepared by co-mixing KL zeolite powder (Tosoh; Si / Al = 3) (70%), precipitated silica (Nyasil20) (30%), and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed, and mixing was continued for 20 minutes. The resulting paste was then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilation furnace at 80 °C for 16 hours and then calcined at 550 °C for 4 hours.

[0146] Catalyst A was obtained by fluidized bed impregnation of the support (in excess). For this purpose, 25 g of the support was pre-calcined in air at 520 °C for 2 hours and then deactivated by dropwise addition of water to the support as it rotated in a ball mill. The Pt(NH3)4Cl2 and KNO3 precursors were dissolved. The deactivated support was placed in a fluidized bed for fluidized bed impregnation. Fluidization was continued at a rate of 25 ml / min for 24 hours.

[0147] After fluidization, the solution was removed. Then the catalyst was washed 4 times with 200 ml of water at a rate of 25 ml / min in the fluidized bed for 30 minutes. The catalyst was dried in an oven at 120 °C for 12 hours, first maintained at 150 °C for 1 hour and then calcined as follows: calcined at 250 °C for 1 hour and at 400 °C for 2 hours.

[0148] Table 1 below details the formulation and properties of Catalyst A.

[0149] Table 1 Example 1: Support A SPC (daN) 0.30 <![CDATA[S BET (m 2 / g)]]> 235 TPV (ml / g) 0.43 Vmacro (ml / g) 0.26 Vmeso (ml / g) 0.12 Vμ (ml / g) 0.085 LOI (%) 7.5 Example 1: Catalyst A <![CDATA[S BET (m 2 / g)]]> 251 Vμ (ml / g) 0.071 Weight % Pt 0.65 % Dispersion of Pt 58

[0150] Example 2: Preparation of Catalyst B Pt / KL-SiO2 (comparative) Support B was prepared by co-mixing KL zeolite powder (Tosoh; Si / Al = 3) (70%), precipitated silica (Siliaflash P60 40 - 63 µm; Silicycle) (10%), colloidal silica sol source (20%) and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed and mixing was continued for 20 minutes. Then the resulting paste was extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilated furnace at 80 °C for 16 hours and then calcined at 550 °C for 4 hours.

[0151] Catalyst B was obtained by fluidized bed impregnation of the support (in excess). For this purpose, 25 g of the support was pre-calcined in air at 520 °C for 2 hours and then deactivated by dropwise addition of water to the support as it rotated in a ball mill. The Pt(NH3)4Cl2 and KNO3 precursors were dissolved. The deactivated support was placed in a fluidized bed for fluidized bed impregnation. Fluidization was continued at a rate of 25 ml / min for 24 hours.

[0152] After fluidization, the solution was removed. Then the catalyst was washed 4 times with 200 ml of water at a rate of 25 ml / min in the fluidized bed for 30 minutes. The catalyst was dried in an oven at 120 °C for 12 hours, first maintained at 150 °C for 1 hour, then calcined at 250 °C for 1 hour and at 400 °C for 2 hours.

[0153] Table 2 below details the formulation and properties of catalyst C.

[0154] Table 2 Example 2: Support B SPC (daN) 0.30 <![CDATA[S BET (m 2 / g)]]> 296 TPV (ml / g) 0.35 Vmacro (ml / g) 0.12 Vmeso (ml / g) 0.21 Vμ (ml / g) 0.085 LOI (%) 5.8 Example 3: Catalyst B <![CDATA[S BET (m 2 / g)]]> 212 Vμ (ml / g) 0.057 Weight % Pt 0.7 % Dispersion of Pt 57

[0155] Example 3: Preparation of Catalyst C Pt / KL-SiO2 (Comparative) Support C was prepared by co-mixing KL zeolite powder (Tosoh; Si / Al = 3)) (70%), precipitated silica (Siliaflash P60 40 - 63 µm; Silicycle) (10%), colloidal silica sol source (20%), and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed, and mixing was continued for 20 minutes. The resulting paste was then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilation oven at 80 °C for 16 hours and then hydrothermally treated at 600 °C for 3 hours in a gas stream containing 50 vol% water in air. The extrudate was then calcined at 550 °C for 2 hours.

[0156] Catalyst C was obtained by fluidized bed impregnation of the support (in excess). For this purpose, 25 g of the support was pre-calcined in air at 520 °C for 2 hours and then deactivated by adding water dropwise to the support as it rotated in a ball mill. The Pt(NH3)4Cl2 and KNO3 precursors were dissolved. The deactivated support was placed in a fluidized bed for fluidized bed impregnation. Fluidization was continued at a rate of 25 ml / min for 24 hours.

[0157] After fluidization, the solution was removed. The catalyst was then washed 4 times with 200 ml of water at a rate of 25 ml / min in the fluidized bed for 30 minutes. The catalyst was dried in an oven at 120 °C for 12 hours, held at 150 °C for 1 hour, then calcined at 250 °C for 1 hour, and further calcined at 400 °C for 2 hours.

[0158] Table 3 below details the formulation and properties of catalyst D.

[0159] Table 3 Example 3: Support C SPC (daN) 0.82 <![CDATA[S BET (m 2 / g)]]> 95 TPV (ml / g) 0.42 Vmacro (ml / g) 0.18 Vmeso (ml / g) 0.14 Vμ (ml / g) 0.027 LOI (%) 3.1 Example 3: Catalyst C <![CDATA[S BET (m 2 / g)]]> 56 Vμ (ml / g) 0.011 Weight % Pt 0.73 % Dispersion of Pt 56

[0160] Example 4: Preparation of Catalyst D Pt / KL-SiO2 (According to the Invention) Support D was prepared by co - mixing KL zeolite powder (Tosoh; Si / Al = 3)) (70%), precipitated silica (Siliaflash C60 (5 - 20 µm; Silicycle) (30%) and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was obtained, and mixing was continued for 20 minutes. Then the resulting paste was extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilated furnace at 80 °C for 16 hours, calcined at 550 °C for 2 hours, and then hydrothermally treated at 500 °C for 3 hours in a gas stream containing 50 vol% water in air. Then the extrudate was calcined at 550 °C for 2 hours.

[0161] Catalyst D was obtained by dry - impregnating support D with a Pt(NH3)4Cl2 solution. For this purpose, 50 g of the support was pre - calcined in air at 520 °C for 2 hours, then placed in a closed container and saturated with water in a humid environment. The Pt(NH3)4Cl2 precursor was dissolved in an aqueous solution. The Pt solution was added dropwise to the support as it rotated in a ball - mill tray for 15 minutes. The catalyst was stored in a closed container for 24 hours, then dried in an oven at 120 °C for 12 hours and calcined at 400 °C.

[0162] Table 4 Support D SPC (daN) 0.78 <![CDATA[S BET (m 2 / g)]]> 183 TPV (ml / g) 0.38 Vmacro (ml / g) 0.15 Vmeso (ml / g) 0.23 Vμ (ml / g) 0.047 LOI (%) 4.9 Catalyst D <![CDATA[S BET (m 2 / g)]]> 127 Vμ (ml / g) 0.027 Weight % Pt 0.95 % Dispersion of Pt 59

[0163] Example 5: Preparation of catalyst E Pt / KL - SiO2 (according to the present invention) Support E was prepared by co - mixing KL zeolite powder (Tosoh; Si / Al = 3)) (70%), precipitated silica (Siliaflash C60 40 - 63 µm; Silicycle) (5%), colloidal silica sol source (25%) and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed, and mixing was continued for 20 minutes. Then the resulting paste was extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilated furnace at 80 °C for 16 hours, dried at 120 °C for 12 hours, and calcined at 550 °C for 2 hours, then hydrothermally treated at 500 °C for 3 hours in a gas stream containing 50 vol% water in air. Then the extrudate was calcined at 550 °C for 2 hours.

[0164] Catalyst E was obtained by dry impregnation of support E with a Pt(NH3)4Cl2 solution. For this purpose, 50 g of the support was pre-calcined in air at 520 °C for 2 h, then placed in a closed container and saturated with water in a humid environment. The Pt(NH3)4Cl2 precursor was dissolved in an aqueous solution. While the support was rotating in a ball mill, the Pt solution was added dropwise to the support over 15 min. The catalyst was stored in a closed container for 24 h, then dried in an oven at 120 °C for 12 h and calcined at 400 °C.

[0165] Table 5 Example 5: Support E SPC (daN) 1.54 <![CDATA[S BET (m 2 / g)]]> 172 TPV (ml / g) 0.40 Vmacro (ml / g) 0.11 Vmeso (ml / g) 0.25 Vμ (ml / g) 0.042 LOI (%) 4.5 Example 5: Catalyst E <![CDATA[S BET (m 2 / g)]]> 126 Vμ (ml / g) 0.022 Weight % Pt 0.95 % Dispersion of Pt 55

[0166] Example 6: Preparation of catalyst F Pt / KL-SiO2 (comparative) Support F was prepared by co-mixing KL zeolite powder (Tosoh; Si / Al = 3)) (70 %), precipitated silica (Siliaflash P60 40-63 µm; Silicycle) (30 %) and Methocel (K15M) (3 % based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed and mixing was continued for 20 min. The resulting paste was then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilation oven at 80 °C for 16 h and then calcined at 550 °C for 4 h.

[0167] Catalyst F was obtained by dry impregnation of support F with a Pt(NH3)4Cl2 solution. For this purpose, 50 g of the support was pre-calcined in air at 520 °C for 2 h, then placed in a closed container and saturated with water in a humid environment. The Pt(NH3)4Cl2 precursor was dissolved in an aqueous solution. While the support was rotating in a ball mill, the Pt solution was added dropwise to the support over 15 min. The catalyst was stored in a closed container for 24 h, then dried in an oven at 120 °C for 12 h and calcined at 400 °C.

[0168] The following Table 6 details the formulation and properties of catalyst F.

[0169] Table 6 Example 6: Support F SPC (daN) 0.30 <![CDATA[S BET (m 2 / g)]]> 233 TPV (ml / g) 0.41 Vmacro (ml / g) 0.14 Vmeso (ml / g) 0.18 Vμ (ml / g) 0.086 LOI (%) 5.1 Example 6: Catalyst F <![CDATA[S BET (m 2 / g)]]> 223 Vμ (ml / g) 0.060 Weight % Pt 0.88 % Dispersion of Pt 56

[0170] Example 7: Preparation of catalyst G Pt / KL-SiO2 (comparative) Support G was prepared by co - mixing KL zeolite powder (Tosoh; Si / Al = 3)) (70%), precipitated silica (Siliaflash P60 40 - 63 µm; Silicycle) (30%) and Methocel (K15M) (3% based on the total mass of the oxides) in a Brabender mixer. Water was added dropwise until a paste was formed and mixing was continued for 20 minutes. The resulting paste was then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudate was aged in a ventilated oven at 80 °C for 16 hours and then hydrothermally treated at 600 °C for 3 hours in a gas stream containing 50 vol% water in air. It was then calcined at 550 °C for 2 hours.

[0171] Catalyst G was obtained by dry - impregnating support F with a Pt(NH3)4Cl2 solution. For this purpose, 50 g of the support was pre - calcined in air at 520 °C for 2 hours and then placed in a closed container and saturated with water in a humid environment. The Pt(NH3)4Cl2 precursor was dissolved in an aqueous solution. As the support rotated in a ball - mill disc, the Pt solution was added dropwise to the support over 15 minutes. The catalyst was stored in a closed container for 24 hours, then dried in an oven at 120 °C for 12 hours and calcined at 400 °C.

[0172] Table 7 below details the formulation and properties of catalyst G.

[0173] Table 7 Example 7: Support G SPC (daN) 0.78 <![CDATA[S BET (m 2 / g)]]> 91 TPV (ml / g) 0.42 Vmacro (ml / g) 0.17 Vmeso (ml / g) 0.12 Vμ (ml / g) 0.028 LOI (%) 3.5 Example 7: Catalyst G <![CDATA[S BET (m 2 / g)]]> 51 Vμ (ml / g) 0.012 Weight % Pt 0.91 % Dispersion of Pt 56

[0174] Example 8: Aromatization of C6 / C7 fractions Approximately 1 g of the prepared catalysts A to G was loaded into a fixed - bed reactor. After the catalysts were loaded, they were dried in a nitrogen stream at 150 °C and then reduced in a hydrogen stream at 470 °C for 12 hours. Then the temperature was lowered to 400 °C and the feedstock was injected.

[0175] The experiments were carried out at 4 bar, where the temperature was scanned between 430 and 500 °C and the H2 / hydrocarbon molar ratio was 4. The feedstock composition is shown in Table 8. The mass flow rate was 1 g of feedstock / (g of catalyst) h. -1 h -1 。

[0176] Table 8 Raw materials C5 0.1 n-P6 6.4 iso-P6 5.8 5N6 5.7 6N6 4.9 A6 1.1 n-P7 18.0 iso-P7 20.5 5N7 11.5 6N7 16.0 A7 7.3 C8 2.7

[0177] Table 9 below summarizes the catalytic performance results of Examples 1 to 7 corresponding to catalysts A to G.

[0178] The feedstock conversion was defined as follows: The flow rate is expressed in g / h; the concentration is expressed in wt%.

[0179] Conversion of i&nP6 - P7=(1 - (Output flow rate x (n - P6 (wt%)+iso - P6 (wt%)+n - P7 (wt%)+iso - P7 (wt%))Output) / (Input flow rate x (n - P6 (wt%)+iso - P6 (wt%)+n - P7 (wt%)+iso - P7 (wt%))Input))x100 P6 and P7 represent normal or iso - alkanes having 6 and 7 carbon atoms respectively.

[0180] The yield of aromatics is defined as follows: Aromatics yield = Output flow rate x (A6 (wt%)+A7 (wt%)+A8 (wt%)) / (Input flow rate) A6, A7 and A8 represent aromatics having 6, 7 and 8 carbon atoms respectively.

[0181] These conversion rates and yields were measured at 480 °C and WHSV = 1.

[0182] Table 9 Catalyst % Conversion of P6P7 % Yield of aromatics Catalyst A (comparative) 83.3% (470 °C, WHSV = 1) 74.3％ Catalyst B (comparative) 80.8％ 75.6％ Catalyst C (comparative) 45.6％ 56.8％ Catalyst D (invention) 88.4％ 80.1％ Catalyst E (invention) 92.4％ 81.7％ Catalyst F (comparative) 83.1％ 73.8％ Catalyst G (comparative) 44.8％ 56.1％

[0183] The comparative catalyst showed a maximum conversion rate of 83.3% for Catalyst A, and a maximum aromatics yield of 75.6% for Catalyst B.

[0184] Catalysts D and E according to the present invention have much higher conversion rates, greater than 86% or even 88%, and the aromatics yield is also greater than 80%. The above Examples 1 to 8 in particular show that the presence of all steps of the method according to the present invention, especially the step of hydrothermally treating the support under the required conditions, is crucial for improving performance and enables the conversion rate of P6P7 to exceed 86% and the aromatics yield to exceed 80%.

Claims

1. A method for preparing an aromatization catalyst, the aromatization catalyst comprising at least 70% by weight of KL zeolite, a heat-resistant SiO2-based oxide, and a Group VIIIB metal, the method comprising at least the following steps: a) Optionally, in the presence of an organic auxiliary, mixing at least one KL zeolite source of structural type LTL and at least one SiO2 source with at least one solvent selected from water, a physical solvent, and a chemical solvent to obtain a mixture; b) Shaping the mixture obtained at the end of step a), preferably by extrusion; c) Optionally aging the shaped material in air at a temperature of 0 to 70 °C, preferably in humid air with a relative humidity of 20% to 100%, for a time of 1 minute to 72 hours; d) Optionally drying the shaped and optionally aged material at a temperature of 0 to 200 °C for a time of 1 minute to 72 hours, and optionally subsequently calcining at a temperature of 200 to 600 °C, preferably 250 to 450 °C, for a time of d') 1 to 12 hours, and preferably 1 to 4 hours; e) Hydrothermally treating the material shaped in step b), optionally aged and optionally dried / calcined, in the presence of steam at a temperature of 200 to 550 °C, preferably at atmospheric pressure, for a time of 30 minutes to 5 hours to obtain a catalyst support; f) Optionally calcining the support obtained at the end of step e) at a temperature of 200 to 680 °C, preferably 400 to 660 °C, for a time of 1 to 12 hours, preferably 1 to 4 hours, to obtain a calcined catalyst support; g) Impregnating with a Group VIII metal, preferably platinum, by contacting the support obtained at the end of step e) or f) with a solution of a precursor of the metal dissolved in an aqueous phase, such that the metal content on the catalyst is 0.1% to 10% by weight, preferably 0.2% to 5% by weight, preferably 0.3% to 2% by weight, and very preferably 0.5% to 1.2% by weight based on the total mass of the anhydrous catalyst; h) Drying the impregnated material obtained at the end of step g), preferably at a temperature of 50 °C to 200 °C; i) Calcining the dried material obtained at the end of step h) in a stream of pure air or air diluted with a neutral gas at a temperature of 200 °C to 500 °C, preferably 250 °C to 450 °C, and very preferably 350 °C to 420 °C to obtain a calcined catalyst; 2. The preparation method according to claim 1, comprising: j) Reducing the calcined catalyst obtained at the end of step i) by contacting the catalyst with a stream of hydrogen, pure or diluted with a neutral gas, at a temperature of 300 °C to 550 °C, preferably 350 °C to 500 °C, and very preferably 450 °C to 500 °C, before contacting with the raw material.

3. The preparation method according to any one of the preceding claims, wherein step a) is carried out by mixing at room temperature for a time of 5 to 60 minutes, and preferably 10 to 50 minutes.

4. The preparation method according to any one of claims 1 to 3, wherein in step a), KL zeolite and SiO₂ silica are introduced in the form of an oxide mixture in the following proportions: - 70% to 90% by weight, preferably 70% to 85% by weight of at least one KL zeolite, and - 10% to 30% by weight, preferably 15% to 30% by weight of at least one SiO₂ silica source, and the mixture is mixed with the following substances: - 10% to 30% by weight of a solvent based on the total weight of the oxide mixture, and - 0% to 20% by weight, preferably 1% to 15% by weight, preferably 1% to 10% by weight, and very preferably 1% to 7% by weight of at least one organic auxiliary based on the total weight of the oxide mixture, The sum of the amounts of the respective compounds introduced in this step is 100%.

5. The preparation method according to any one of the preceding claims, wherein in step a), a single silica source is used, preferably precipitated silica or silica gel, and very preferably precipitated silica.

6. The preparation method according to any one of claims 1 to 4, wherein in step a), two different silica sources are used.

7. The preparation method according to claim 6, wherein the two silica sources are precipitated silica and colloidal silica sol.

8. The preparation method according to any one of claims 5 to 7, wherein the particle size or granularity of the silica used in step a) is less than 100 μm, preferably less than 80 μm, more preferably less than 60 μm, even more preferably less than 20 μm or practically less than 10 μm for precipitated silica or silica gel, and 5 to 200 nm, preferably 15 to 50 nm for colloidal silica sol.

9. The preparation method according to any one of the preceding claims, wherein the organic auxiliary is selected from cellulose derivatives, polyethylene glycol, aliphatic monocarboxylic acids, alkyl aromatic compounds, sulfonates, fatty acids, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide polymers, scleroglucan, hydroxyethyl cellulose derivatives, carboxymethyl cellulose, lignosulfonates, and galactomannan derivatives, which are used alone or as a mixture, and preferably carboxymethyl cellulose.

10. The preparation method according to any one of the preceding claims, wherein the carrier obtained at the end of step e) or f) has a specific surface area of 80 to 200 m 2 / g, a total pore volume of 0.35 to 0.6 cm 3 / g, a macropore volume of 0.08 to 0.16 cm 3 / g, a mesopore volume of 0.2 cm 3 / g to 0.4 cm 3 / g, a micropore volume of less than 0.07 cm 3 / g, a sodium content of less than 0.2% by weight, and a mechanical strength of at least greater than or equal to 0.5 daN / mm, preferably at least greater than or equal to 0.6 daN / mm, and preferably at least greater than or equal to 0.7 daN / mm, measured by the single-grain crushing test (hereinafter referred to as SPC).

11. A method according to any one of the preceding claims, step e) or f) to obtain an aromatization catalyst support in the form of a composite KL zeolite - SiO2 material, which comprises at least 70% KL zeolite, having a specific surface area of 80 to 200 m 2 / g, a total pore volume of 0.35 to 0.6 cm 3 / g, a macropore volume of 0.08 to 0.16 cm 3 / g, a mesopore volume of 0.2 to 0.4 cm 3 / g and a micropore volume of less than 0.07 cm 3 / g, a sodium content of less than 0.2% and a mechanical strength of at least greater than or equal to 0.5 daN / mm, preferably at least greater than or equal to 0.6 daN / mm, and preferably at least greater than or equal to 0.7 daN / mm, measured by a single - grain crushing test (hereinafter referred to as SPC).

12. A catalyst for the aromatization of C6-C8 paraffin fractions, which can be prepared by the method according to any one of claims 1 to 10, comprises at least 70% by weight of KL zeolite with an Si / Al ratio of 2.8 to 4, preferably 2.8 to 3.5, and a structure type of LTL, 10% to 30% by weight of a high-temperature resistant oxide of SiO2 silica, a Group VIIIB metal, preferably platinum. The catalyst also has a specific surface area of 80 to 200 m 2 / g, a micropore volume of less than 0.04 cm 3 / g, a Group VIIIB metal content of 0.1% to 10% by weight, preferably 0.2% to 5% by weight, very preferably 0.3% to 2% by weight, and even more preferably 0.5% to 1.2% by weight of the metal, and a dispersion of 50% to 70% of the metal.

13. The aromatization catalyst according to claim 12, wherein the metal is platinum and the platinum content is 0.6% to 1.0% by weight based on the total weight of the catalyst.

14. The aromatization catalyst according to any one of claims 12 and 13, wherein the KL zeolite content is 70% to 85% by weight and the high-temperature resistant oxide content is 15% to 30% by weight, and the sum of the overall components of the catalyst including the metal is 100%.

15. A method for aromatizing at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising a C6-C8 paraffin fraction, which is carried out by contacting the catalyst prepared according to any one of claims 1 to 10 or the catalyst according to any one of claims 12 to 14 with the gaseous feedstock to be treated in the presence of hydrogen, the method being carried out in the liquid phase or the gas phase at a temperature of 400 °C to 550 °C, at a pressure of 2 to 20 MPa, at a molar ratio of hydrogen to hydrocarbon compound of 1 to 10, and at a weight hourly space velocity WHSV of 1 to 10 h -1 -1.

16. The aromatization method according to claim 15, wherein the conversion rate of n-alkanes and iso-alkanes to C6-C7 is greater than or equal to 85%, and the aromatic hydrocarbon yield is greater than or equal to 80%.

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