Aromatization catalyst having a high kl zeolite content

Abstract

The invention relates to a process for preparing an aromatization catalyst comprising at least 70% KL zeolite, a silica (SiO2) refractory oxide and a group VIIIB metal, involving a hydrothermal treatment of the support in the presence of water vapor. The invention also relates to the specific support obtained, said aromatization catalyst, and a method for aromatization of at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising C6-C8 paraffin fractions, using said aromatization catalyst.

Description

[0001] KL HIGH ZEOLITE AROMATIZATION CATALYST

[0002] TECHNICAL FIELD

[0003] The present invention relates to a catalyst consisting of a microporous material shaped in a binder consisting of at least one source of silica in the form of extrudates, tablets or beads containing at least 70% by mass of KL zeolite (LTL structural type).

[0004] PRIOR TECHNIQUE

[0005] Zeolites are crystalline aluminosilicate materials with organized microporosity formed by the three-dimensional arrangement of SiO4 tetrahedra 4- and AIO4 5-thus providing a wide diversity of structures. The International Zeolite Association (IZA) has classified zeolites according to their structures (structural types). Zeolites are widely used in industry for adsorption, separation, catalysis and ion exchange. KL zeolite is an LTL structural type zeolite containing a one-dimensional microporous system with pore openings of 12 T atoms (T being silicon or aluminum). The charge-compensating cation of the structure is K +. To be used in industrial processes, zeolites are shaped to obtain objects larger than zeolite crystals and thus facilitate their handling, but also facilitate the passage of the charge in the reactors. It is very difficult to shape pure KL zeolite and obtain a product with good mechanical resistance. Usually, to obtain a shaped object containing a high percentage of KL zeolite, conventional methods use clays, aluminas or silicas which are mixed with the zeolite for shaping. The nature of the binder chosen impacts not only the mechanical resistance of the catalyst but also its performance.

[0006] The preparation of catalysts from KL zeolite in the presence of silica is known.

[0007] US Patent 4,830,732 presents in particular a method for obtaining a shaped material containing a KL zeolite. The method consists of mixing a KL zeolite with a silica source or a pseudo-boehmite source, then shaping the mixture by kneading-extrusion. Aluminum nitrate is added to improve the catalyst's sensitivity to water (WSI = Water Sensitivity Index). US Patent 5,354,933 presents a method for obtaining a shaped material containing a KL zeolite. The method consists of mixing a KL zeolite with a silica and then shaping the mixture by kneading-extrusion. The percentage of KL zeolite relative to the total mass of KL zeolite and silica is 83%. Platinum and one or more halogenated compounds are then deposited.The patent presents catalysts with improved performance when the Pt XANES peak has an intensity greater than or equal to 0.4 and a dealumination rate greater than or equal to 3% is obtained. No textural data is mentioned.

[0008] US Patent 6,207,042 presents a method for obtaining a shaped material containing a KL zeolite. The method consists of mixing a KL zeolite with silica and methocel and then shaping the mixture by kneading-extrusion. The percentage of KL zeolite relative to the total mass of KL zeolite and silica is 83% and a single source of silica, colloidal sol, is used. The preparation of the catalyst supports also requires numerous washes to remove residual alkalis from the silica precursors and extrusion aids. Halogenated compounds of the fluorine or chloride types are used. The patent does not present any data on the mechanical strength of the extrudates obtained. The catalysts impregnated on the washed materials exhibit better stability with improved cycle times.

[0009] US Patent 8,263,518 discloses a material shaped into extrudates containing a KL zeolite and silica. The mechanical strength of the extrudates obtained is greater than 3 Ib / mm (1.3 daN / mm). This improved mechanical strength is attributed to the use of the zeolite in the form of aggregates with dimensions between 1.4 pm and 6 pm. Furthermore, the process requires the use of halogenated compounds of the fluorine or chloride types.

[0010] Patent application WO 2019 / 217054A1 describes the preparation of a catalyst for aromatizing a C6-C8 fraction comprising a KL zeolite, a binder (silica in the examples), platinum and halides. This patent shows that if some of the intermediate calcination steps are omitted, the catalyst remains as efficient as the catalyst prepared under standard conditions with a preparation process including three calcination steps.

[0011] US patent application 2018 / 169,638 relates to a platinum catalyst on a KL zeolite and refractory oxide support, the preparation process of which includes a washing step to enrich the catalyst with K or Cs. The catalyst has a micropore volume of between 0.015 and 0.05 cc / g, an SBET of between 100 and 170 rrï7g. It also contains chlorine and fluorine.

[0012] Patent application US2014 / 008833 describes a regenerable catalyst containing a zeolite, preferably KL, exchanged with preferably barium, a binder, of high SBET and high pore volume according to a preparation protocol including an ion exchange of the zeolite.

[0013] The C6-C8 fraction aromatization catalysts described in the prior art essentially consist of a zeolite (preferably KL) formed in a silica binder. The active metal can be platinum. Various preparation methods are reported: ion exchange of the KL zeolite, or the presence of washings (to reduce the Na content), or the presence of halogenated compounds. The support and the catalyst undergo one or more heat treatments of the calcination type.

[0014] For aromatization of C6 / C8 fractions, the use of silica as a binder proves to be the best choice in terms of catalytic performance. Silica has a more neutral character than alumina. An alumina-type binder with more OH sites than silica would promote unwanted cracking reactions.

[0015] It is known that silica, which is an interesting compound to use as a support for catalysts, cannot be extruded like other materials in conventional extrusion equipment to give products sufficiently resistant to be implemented in processes. Indeed, from its manufacture to its implementation, the catalyst is confronted with numerous stages which can impact its physical integrity. In particular, it must be resistant to crushing, attrition and pressure variations linked to the operating conditions of the catalytic reactor in which it is operated. Thus, there is a constant need for high-performance catalysts with improved mechanical and physical properties.

[0016] SUMMARY OF THE INVENTION

[0017] Surprisingly, the Applicant discovered that a specific preparation process implementing in particular a hydrothermal treatment in the presence of water vapor of a support based on a refractory oxide of the SiO2 type and a KL zeolite before impregnation with a group VIII metal made it possible to obtain an aromatization catalyst with improved catalytic properties and good mechanical resistance. The process according to the invention also has the advantage of being more environmentally friendly by avoiding water-consuming washing and the use of harmful halides.

[0018] The invention relates to a process for preparing an aromatization catalyst comprising at least 70% by weight of KL zeolite, a refractory oxide of silica type SiO2 and a metal from group VII IB, comprising at least the following steps: a) a step of mixing at least one source of KL zeolite of structural type LTL, at least one source of silica SiO2, with at least one solvent chosen from water, physical solvents and chemical solvents, optionally in the presence of an organic adjuvant to obtain a mixture, b) a step of shaping, preferably by extrusion, the mixture obtained at the end of step a), c) an optional step of maturing the shaped material at a temperature of between 0 and 70°C, for a period of between 1 minute and 72 hours, in air, preferably in humid air with a relative humidity of between 20 and 100%;d) an optional drying step of the shaped and optionally matured material at a temperature of between 0 and 200°C, for a duration of between 1 minute and 72 hours; optionally followed by calcination d') at a temperature of between 200 and 600°C, preferably between 250 and 450°C for a duration of between 1 and 12 h and preferably between 1 and 4 h; e) a step of hydrothermal treatment of the material shaped in step b), optionally matured in step c) and optionally dried / calcined in step d), in the presence of water vapor, at a temperature of between 200 and 550°C, preferably under atmospheric pressure and, for a duration of between 30 minutes and 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 between 200 and 680°C, preferably between 400 and 660°C for a duration of between 1 and 12 h and preferably between 1 and 4 h, to obtain a calcined catalyst support; g) a step of impregnation of a metal from group VIII, preferably platinum, by contacting the support obtained at the end of step e) or f) with a solution of a precursor of said metal dissolved in the aqueous phase, such that the metal content on the catalyst is between 0.1% and 10% by weight, preferably from 0.2% to 5% by weight, preferably from 0.3% to 2% by weight, and very preferably from 0.5% to 1.2% by weight relative to 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 between 50°C and 200°C;i) a step of calcining the dried material obtained at the end of step h) under a gas flow of either pure air or air diluted with a neutral gas between 200°C and 500°C, preferably between 250°C and 450°C and very preferably between 350°C and 420°C, to obtain a calcined catalyst.;

[0019] The preparation process may comprise: j) a step of reducing the calcined catalyst obtained at the end of step i) carried out before contacting with the feedstock, by contacting with a flow of gas containing hydrogen, pure or diluted with a neutral gas, at a temperature between 300°C and 550°C, preferably between 350°C and 500°C and very preferably between 450°C and 500°C.

[0020] Step a) can be carried out by mixing at room temperature, for a period of between 5 and 60 min, and preferably between 10 and 50 min.

[0021] In step a) zeolite KL and silica SiO2 can be introduced as a mixture of oxides in the following proportions:

[0022] - 70% to 90% by weight, preferably 70% to 85% by weight of at least one KL zeolite,

[0023] - 10 to 30% by weight, preferably 15 to 30% by weight of at least one source of silica SiO 2 ; and we can add to the mixture:

[0024] - 10 to 30% by weight of solvent, relative to the total weight of said mixture of oxides;

[0025] - 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 of at least one organic adjuvant, relative to the total weight of said mixture of oxides; the sum of the contents of each of the compounds introduced at this stage being equal to 100%. A single source of silica may be used in stage a), preferably a precipitated silica or a silica gel, very preferably a precipitated silica.

[0026] Two different silica sources can be used in step a), preferably the two silica sources are a precipitated silica and a colloidal silica sol.

[0027] The silica used in step a) may have a grain size or particle size of less than 100 pm, and preferably less than 80 pm, even more preferably less than 60 pm, even more preferably less than 20 pm, or even less than 10 pm for precipitated silica or silica gel and between 5 and 200 nm, preferably between 15 and 50 nm for colloidal silica sol.

[0028] The organic adjuvant may be selected from cellulose derivatives, polyethylene glycols, aliphatic monocarboxylic acids, alkylated aromatic compounds, sulfonic acid salts, fatty acids, polyvinyl pyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide-type polymers, scleroglucan, hydroxyethylated cellulose-type derivatives, carboxymethylcellulose (e.g. Methocel™), lignosulfonates and galactomannan derivatives, taken alone or in a mixture, preferably carbomethylcellulose.

[0029] The support obtained at the end of step e) or f) may have a specific surface area of ​​between 80 and 200 m 2 / g, a total pore volume between 0.35 and 0.6 cm 3 / g, a macropore volume between 0.08 and 0.16 cm 3 / g, a mesoporous volume between 0.2 cm 3 / g and 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 resistance measured by the grain-to-grain crushing test, subsequently noted EGG, 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.

[0030] The invention also relates to an aromatization catalyst support, in the form of a KL-SiO2 zeolite composite material, comprising at least 70% of KL zeolite, obtained in step e) or f) of the process according to any one of the variants described, having a specific surface area of ​​between 80 and 200 m 2 / g, a total pore volume between 0.35 and 0.6 cm 3 / g, a macropore volume between 0.08 and 0.16 cm 3 / g, a mesoporous volume between 0.2 cm 3 / g and 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 resistance measured by the grain-to-grain crushing test, subsequently noted EGG, 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.

[0031] The invention also relates to a catalyst for aromatization of C6-C8 paraffinic cuts capable of being prepared by the process according to any one of the variants described comprising at least 70% by weight of KL zeolite of LTL structural type having a Si / Al ratio of between 2.8 and 4, preferably between 2.8 and 3.5, between 10 and 30% by weight of a refractory oxide of silica type SiO2, a metal from group VIII B, preferably platinum, said catalyst further having a specific surface area of ​​between 80 and 200 rrï7g, a microporous volume of less than 0.04 cm3 / g, a content of metal from group VII IB, of between 0.1 and 10%, preferably between 0.2% and 5% by weight, very preferably between 0.3% and 2% by weight, and even more preferably from 0.5% to 1.2% by weight. of metal and a dispersion of said metal of between 50 and 70%.

[0032] The metal may be platinum and the platinum content may be between 0.6 and 1.0% by weight relative to the total weight of catalyst.

[0033] The KL zeolite content of the catalyst may be between 70 and 85% by weight and the refractory oxide content of the catalyst may be between 15 and 30% by weight, the sum of all the constituents of the catalyst including the metal being equal to 100%.

[0034] The invention finally relates to a process for aromatizing at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising C6-C8 paraffinic cuts by bringing the catalyst prepared according to any one of the variants described or the catalyst according to any one of the variants described into contact with the gaseous feedstock to be treated in the presence of hydrogen, said process being carried out in the vapor or liquid phase, at a temperature between 400°C and 550°C, at a pressure between 2 and 20 MPa, at a molar ratio of hydrogen to hydrocarbon compounds between 1 and 10, at an hourly mass flow rate PP H between 1 and 10 h 1 .

[0035] The aromatization process can have a conversion of n and iso paraffins to C6-C7 greater than or equal to 85% and an aromatic yield greater than or equal to 80%.

[0036] DESCRIPTION OF EMBODIMENTS

[0037] The invention will be detailed below using non-limiting embodiments and examples. Furthermore, particular and / or preferred embodiments of the invention may be described. They may be implemented separately or combined with each other, without limitation of combination when this is technically feasible.

[0038] Definitions

[0039] Mass percentages are expressed, unless otherwise indicated, relative to the anhydrous mass of the final composite material (support or catalyst). This anhydrous mass is determined by a so-called Loss on Ignition (LOI) measurement corresponding to the mass variation resulting from heating the sample to 1000°C for 2 hours. The loss on ignition is expressed as a percentage by mass of the dry matter.

[0040] Throughout the rest of the text, the term “lateral crushing strength” means the mechanical strength of the material according to the invention (support or catalyst) determined by the grain-to-grain crushing (GTC) test. This is a standardized test (ASTM D4179-01 standard) which consists of subjecting a material in the form of a millimeter-sized object, such as a ball, a pellet or an extrudate, to a compressive force generating rupture. This test is therefore a measure of the tensile strength of the material. The analysis is repeated on a certain number of individual solids and typically on a number of solids between 10 and 200. The average of the measured lateral breaking forces constitutes the average GTC which is expressed in the case of granules in units of force (N), and in the case of extrudates in units of force per unit of length (daN / mm or decaNewton per millimeter of extrudate length).

[0041] Throughout the rest of the text, specific surface area means the BET specific surface area (SBET) determined by nitrogen adsorption in accordance with ASTL D 3663-78 established from the BRUNAUER-AMMETT-TELLER method described in the periodical “The Journal of American Society”, 60, 309, (1938).

[0042] By "macropores" we mean pores with an opening greater than 50 nm.

[0043] By "mesopores" we mean pores with an opening between 2 nm and 50 nm, inclusive.

[0044] By "micropores" we mean pores with an opening of less than 2 nm.

[0045] The total pore volume (TPV) of the material, support or catalyst, according to the invention, is understood to mean the volume measured by intrusion with a mercury porosimeter according to standard ASTM D4284-83 at a maximum pressure of 4000 bars (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140°. The wetting angle was taken equal to 140° following the recommendations of the work “Techniques de l'ingénieur, traité analyse et caractérisation”, pages 1050-1055, written by Jean Charpin and Bernard Rasneur.

[0046] For greater accuracy, the total pore volume value is the total pore volume value measured by mercury porosimeter intrusion measured on the sample minus the total pore volume value measured by mercury porosimeter intrusion measured on the same sample at a pressure corresponding to 30 psi (approximately 0.2 MPa).

[0047] The volume of macropores and mesopores was measured by mercury intrusion porosimetry according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140°. The value at which mercury fills all intergranular voids was set at 0.2 MPa, and above this value, mercury was considered to penetrate into the pores of the sample.

[0048] The macroporous volume of the material, support or catalyst, according to the invention is defined as being the cumulative volume of mercury introduced at a pressure between 0.2 MPa and 30 MPa, corresponding to the volume contained in the pores with an apparent diameter greater than 50 nm.

[0049] The mesoporous volume of the material, support or catalyst, according to the invention is defined as being the cumulative volume of mercury introduced at a pressure between 30 MPa and 400 MPa, corresponding to the volume contained in the pores with an apparent diameter between 2 and 50 nm. The median diameter of the macropores (Dmacro in nm) of the material, support or catalyst, according to the invention is defined as being a diameter such that all the pores smaller than this diameter constitute 50% of the macroporous volume, measured by mercury porosimetry.

[0050] The median diameter of the mesopores (Dmeso in nm) of the material, support or catalyst, according to the invention is defined as being a diameter such that all the pores of a size smaller than this diameter constitute 50% of the mesoporous volume, measured by mercury porosimetry.

[0051] The microporous volume of the material, support or catalyst, is preferably calculated by the t-plot method from the nitrogen adsorption isotherm at the temperature of 77 Kelvin (77K), after degassing under vacuum (P < 6.7.10 4 Pa), at a temperature between 200 and 650°C for a period of 9 hours to 16 hours, preferably at 500°C for 10 hours. The measurement of the nitrogen adsorption isotherm at 77 Kelvin (77K) is then carried out on a Micromeritics ASAP 2020 M type device, taking at least 35 measurement points at relative pressures of ratio P / P obetween 0.002 and 1. The micropore volume is determined from the isotherm obtained, by the t-plot method applying the ISO 15901-3:2007 standard and calculating the statistical thickness t by the Harkins-Jura equation. The micropore volume is obtained by linear regression on the points of the t-plot, respectively from the ordinate at the origin and the slope of the linear regression. The evaluated micropore volume is expressed in cm 3 of liquid adsorbate per gram of anhydrous adsorbent.

[0052] The microporous volume can also be used to verify the percentage of KL zeolite present in the different stages of the manufacturing process of the catalyst according to the invention, which comprises at the end of the process at least 70% by mass of KL zeolite. It is considered that pure KL zeolite has a microporous volume of 0.140 cm 3 / g. A micropore volume less than 0.140 cm 3 / g indicates the presence of amorphous matter without microporosity in the material or a possible partial blockage of the zeolite microporosity. In the absence of partial blockage of the zeolite microporosity, the value of the micropore volume is proportional to the quantity of KL zeolite present in the mixture. For example, a micropore volume of 0.070 cm 3 / g means that the mixture contains 50% KL zeolite.

[0053] The molar quantities of the different elements present in the material can be determined by the X-ray fluorescence method. The method makes it possible, in particular, to determine the Si / Al ratio of a zeolitic microporous material. For a pure or high-purity KL zeolite, the Si / Al ratio is generally between 2.8 and 4.3, excluding the upper limit.

[0054] X-ray fluorescence (FX) spectrometry is a chemical analysis technique that uses a physical property of matter, X-ray fluorescence. It allows the analysis of most chemical elements from Beryllium (Be) in concentration ranges from a few ppm to 100%, with accurate and reproducible results. X-rays are used to excite the atoms in the sample, causing them to emit X-rays with energies characteristic of each element present. The intensity and energy of these X-rays are then measured to determine the concentration of the elements in the catalyst, including the Pt and Cl content.

[0055] H2O2 titration is a dynamic chemisorption measurement technique used to determine the state of dispersion of the metal, particularly platinum Pt, on the catalyst after its reduction.

[0056] The solid is brought into equilibrium under a flow of carrier gas (He) containing small quantities of the "probe" gas which are sent by pulses. Each pulse contains known quantities of adsorbate. The quantity adsorbed by the solid is measured by the difference between the proportion of "probe" gas at the inlet and outlet of the reactor. The analytical apparatus used to carry out dynamic chemisorptions is a Xorb type tool from the company GIRA (T135).

[0057] The titration measurements are carried out on approximately 2g of sample, after an initial calcination step at 400°C / 2h in air then reduction at 470°C / 2h in H2. After returning to room temperature, a first series of O2 pulses is carried out to measure the 1 er volume of oxygen chemisorbed on the metal, in particular platinum, of the catalyst (V1), then after a reduction of 1 h at room temperature a second series of O2 pulses is carried out to measure the 2 èmevolume of oxygen chemisorbed on the metal, in particular platinum, of the catalyst (V2).

[0058] A theoretical oxygen consumption volume assuming all metal atoms (e.g. platinum) are accessible is calculated as follows:

[0059] Math 1

[0060] The dispersion of the metal (for example platinum) is then obtained according to the formula:

[0061] Math 2 2

[0062] ° ~ VTH

[0063] Throughout this text:

[0064] The term "support" refers to the material consisting of KL zeolite (a) and a refractory silica-type oxide (b) shaped, preferably by kneading / extrusion.

[0065] The previously defined support to which the group VII IB (c) metal such as platinum is added is called a "catalyst".

[0066] For the purposes of the present invention, the various embodiments presented may be used alone or in combination with each other, without limitation of combination. For the purposes of the present invention, the various parameter ranges for a given step such as pressure ranges and temperature ranges may be used alone or in combination. For example, for the purposes of the present invention, a preferred pressure value range may be combined with a more preferred temperature value range.

[0067] The aim of the invention is to propose a catalyst suitable for the aromatization of C6 / C8 or C6 / C7 hydrocarbon cuts, comprising in particular:

[0068] (a) a KL zeolite (structural type LTL) with a Si / AI molar ratio advantageously between 2.8 and 4, preferably between 2.8 and 3.5, very preferably the Si / AI molar ratio is equal to 3

[0069] (b) a refractory oxide of silica type,

[0070] (c) a group VIII B metal.

[0071] Surprisingly, the Applicant discovered that a process for preparing a catalyst starting from a mixture of KL zeolite in the presence of at least one source of synthetic silica with a low sodium content using a hydrothermal type heat treatment in the presence of water vapor (commonly called "steaming"), led, after addition of platinum, to a catalyst having improved performances in aromatization of C6 / C8 cuts, in particular C6 / C7, compared to the catalysts of the prior art, and had different textural characteristics, while ensuring high mechanical strength.

[0072] The catalyst according to the invention is therefore in the form of an active phase based on KL zeolite, to which a refractory oxide of the silica type SiO2 is added, which will serve as a binder, to constitute the support, and to which a metal from group VIIIB is finally added, such as platinum, to constitute the catalyst (without prejudging the order in which and the manner in which these different compounds are introduced).

[0073] Preferably, the content of (b) refractory oxide, in the form of silicon oxide, is between 10% and 30% by weight of the support, and very preferably between 15 and 30% by weight of the support.

[0074] Preferably, the specific surface area S_BET of the support is at least 80 m 2 / g, preferably between 120 and 200 m 2 / g. Such a specific surface area for the catalyst support makes it possible in particular to obtain good catalytic activity. Advantageously, the content of (a) KL zeolite in the catalyst is chosen to be at least 70% by weight, in particular between 70 and 85% by weight relative to the total weight of catalyst. The content of refractory oxide of the SiO2 type in the catalyst is between 10 and 30%, preferably between 15 and 30% by weight relative to the total weight of catalyst.

[0075] Preferably, the (c) metal of group VI 11 B may be an element of the platinum group, in particular Pt or Pd, preferably Pt. Preferably, the content of (c) metal of group VIII may be between 0.1% and 10% by weight, preferably from 0.2% to 5% by weight, very preferably from 0.3% to 2% by weight, and even more preferably from 0.5% to 1.2% by weight, very advantageously between 0.6% and 1.0% by weight relative to the total weight of catalyst. In a very preferred embodiment, the catalyst may comprise platinum at a content of between 0.6 and 1.0% by weight, relative to the total weight of catalyst.

[0076] The total sum of the weight percentages of the catalyst constituents is equal to 100%.

[0077] The invention also relates to a process for preparing the catalyst as described above and which comprises the following steps:

[0078] - mixture of KL zeolite with at least one refractory oxide of silica type,

[0079] - shaping the mixture obtained, for example by extrusion,

[0080] - possible maturation, possible drying or possible calcination of the mixture shaped in the previous step

[0081] - hydrothermal treatment in the presence of water vapor of the material shaped in the previous step to obtain a support,

[0082] - possible calcination of the support obtained in the previous step

[0083] - impregnation of the support with a precursor of the group VI metal 11 B

[0084] - drying and calcination of the impregnated support to obtain a catalyst.

[0085] The invention also relates to the use of the catalyst described above in a process for aromatizing hydrocarbon feedstock comprising C6-C8 paraffinic cuts (hydrocarbon chains comprising e to 8 carbon atoms).

[0086] The invention also relates to a process for aromatizing at least one alkane or cycloalkane contained in a C6-C8 hydrocarbon feedstock, such that said process is carried out in the vapor or liquid phase, at a temperature between 400°C and 550°C, at a pressure between 2 and 20 MPa, at a molar ratio of hydrogen to hydrocarbon compounds between 1 and 10, at an hourly mass flow rate PP H between 1 and 10 h -1 , and with a catalyst according to any one of the variants described and in particular in the form of an oxide comprising

[0087] (a) a KL zeolite (structural type LTL) with a Si / AI molar ratio of between 2.8 and 4, preferably 2.8 to 3.5, more preferably equal to 3,

[0088] (b) a refractory oxide of silica type,

[0089] (c) a group VIII B metal.

[0090] Schematically and in accordance with the invention, the process for preparing the catalyst comprises at least the following steps: a) a step of mixing at least one source of KL zeolite (structural type LTL), at least one source of silica in at least one solvent to obtain a mixture, mixture operated in particular in the form of a mixture of zeolite and silica powders and / or a mixture of zeolite powder and silica sol in a proportion such that the zeolite content in the final material is at least 70% and / or a mixture of zeolite powder and silica powder and silica sol, in a proportion such that the zeolite content in the final material is at least 70%. Any combination of KL zeolite and at least one source of silica SiO2 in the starting mixture can be used,so that the proportions of zeolite KL and refractory oxide SiO2 in the catalyst according to the invention are respected. Preferably the silica source has a low sodium content, advantageously less than 1000 ppm. b) a step of shaping the mixture obtained at the end of step a), c) an optional maturation step of the shaped material obtained at the end of step b) d) an optional drying step e) a step of hydrothermal treatment in the presence of water vapor of the shaped material (optionally matured in step c) and optionally dried / calcined in step d)),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 a metal from group VIII by bringing the support obtained at the end of step e) or f) into contact with a solution obtained by dissolving the metal precursor in aqueous phase h) a step of drying the impregnated support obtained at the end of step g) i) a step of calcining the dried impregnated support 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 can be carried out prior to its use in a catalytic process.,

[0091] The preparation process and its different stages are described in detail below.

[0092] Step a) mixing

[0093] According to the invention, said step a) consists of mixing at least one source of KL zeolite, at least one source of silica with at least one solvent (for example water) to obtain a mixture which can be shaped.

[0094] The silica source can be chosen from all silica sources known to those skilled in the art, alone or as a mixture with each other, for example precipitated silica powders, silica gels, colloidal silica sols.

[0095] Preferably, the precipitated silica powder(s) or silica gel(s) are chosen, without being restrictive, preferably from low sodium silicas (Na<1000 ppm), in particular from the following commercial sources: Nyasil20 (Nyacol ®), Siliaflash P60 (Silicycle ®), Siliaflash C60 (Silicycle ®), Ultrasil VN3 GR (Evonik ®).

[0096] Preferably, the colloidal silica sols are chosen, without being restrictive, from the following commercial sources: Ludox (WR 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®).

[0097] Most colloidal silica sols are prepared from sodium silicate and inevitably contain sodium. Since the presence of sodium can be detrimental to catalytic activity, an ion exchange step may be necessary to reduce or even eliminate residual sodium. To avoid this step, the use of low-sodium colloidal silica sols is preferable, particularly silica sols stabilized with an ammonium counterion. Examples include Ludox AS40 stabilized with an ammonium counterion, or Nalco 1034A, Ultra-Sol 7H, or NexSil 20A.

[0098] Said source(s) of silica(s) used in the process according to the present invention are advantageously synthetic amorphous silicas and not natural silicas which may contain too many impurities.

[0099] Preferably, at least one organic adjuvant may also be mixed during step a).

[0100] Said organic adjuvant can also be chosen from all the additives known to those skilled in the art.

[0101] In the case where at least one organic adjuvant is added in step a), said organic adjuvant may advantageously be chosen from cellulose derivatives, polyethylene glycols, aliphatic monocarboxylic acids, alkylated aromatic compounds, sulfonic acid salts, fatty acids, polyvinyl pyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide-type polymers (such as xanthan gum), scleroglucan, hydroxyethylated cellulose-type derivatives, carboxymethylcellulose (for example Methocel™), lignosulfonates and galactomannan derivatives, taken alone or in a mixture, preferably the organic adjuvant is carbomethylcellulose.

[0102] Preferably, said organic adjuvant can be mixed in powder form or in solution in said solvent.

[0103] Said solvent may advantageously be chosen from water, physical solvents and chemical solvents, in particular ethanol, alcohols and amines. Preferably, said solvent is water.

[0104] Within the scope of the invention, it is entirely possible to make mixtures of several different silica powders and / or different silica sols.

[0105] The order in which the mixing of the powders of at least the silica sources and the KL zeolite source, and optionally at least one organic adjuvant in the case where these are mixed in the form of powders, with at least one solvent is carried out is indifferent. The mixing of said powders and said solvent can advantageously be carried out in a single operation.

[0106] The addition of powders and solvent can also be advantageously alternated.

[0107] The solvent is added to the mixture of powders or powder and sol, in such a quantity that the mixture can be shaped, for example by extrusion. The quantity of solvent introduced can in particular be between 30 and 40% of the total mass of the mixture of oxides (KL zeolite and silica).

[0108] Preferably, the silica introduced in the form of precipitated silica or silica gel in step a) has a grain size or particle size of less than 100 μm, very preferably less than 80 μm, even more preferably less than 60 μm, even more preferably less than 20 μm, or even less than 10 μm. Preferably, the colloidal silica has a grain size or particle size of between 5 and 200 nm, preferably between 15 and 50 nm.

[0109] Preferably, said mixing step a) is carried out by kneading, in batch or continuously.

[0110] In the case where said step a) is carried out in batch, said step a) is advantageously carried out in a mixer preferably equipped with Z-shaped arms, or cams, or in any other type of mixer such as for example a planetary mixer. Said mixing step a) makes it possible to obtain a homogeneous mixture of the powdered constituents.

[0111] Preferably, said step a) is carried out by mixing at room temperature, for a period of between 5 and 60 min, and preferably between 10 and 50 min. The rotation speed of the mixer arms is advantageously between 10 and 75 revolutions / minute, preferably between 25 and 50 revolutions / minute.

[0112] Preferably, in step a) of mixing of the process according to the invention, the KL zeolite and the silica are introduced in the following proportions:

[0113] - 70% to 90% by weight, very preferably 70% to 85% by weight of at least one KL zeolite (having a Si / AI ratio of between 2.8 and 4.3, excluding the upper limit),

[0114] - 10 to 30% by weight of silica in the form of SiO2 oxide provided by one or more silica sources; To this mixture of powders, the following are added, relative to the sum of the oxides introduced (KL zeolite and silica):

[0115] 30 to 40% by weight of solvent

[0116] 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 of at least one organic adjuvant, in the mixture. the weight percentages being expressed relative to the total weight of said anhydrous material and the sum of the contents of each of the compounds in the mixture being equal to 100%.

[0117] Step b) formatting

[0118] In accordance with the invention, said step b) consists of 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, pelletizing, spheronization, granulation, etc.

[0119] Preferably, the mixture obtained at the end of step a) can be shaped by extrusion.

[0120] In the case where the shaping of the mixture resulting from step a) is carried out by extrusion, said step b) can advantageously be carried out in a piston, single-screw or twin-screw extruder.

[0121] In this case, an organic adjuvant may optionally be added in mixing step a). The presence of said organic adjuvant facilitates shaping by extrusion. Said optional organic adjuvant is described above and is introduced in step a) in the proportions indicated above.

[0122] In the case where said preparation process is carried out continuously, said mixing step a) may be coupled with step b) of shaping by extrusion in the same equipment. According to this implementation, the extrusion of the mixture also called "kneaded paste" may be carried out either by extruding directly at the end of a continuous mixer of the twin-screw type for example, or by connecting one or more batch mixers to an extruder. The geometry of the die, which gives the extrudates their shape, may be chosen from dies well known to those skilled in the art. They may thus be, for example, cylindrical, multi-lobed, fluted or slotted.In the case where the shaping of the mixture resulting from step a) is carried out by extrusion, the quantity of solvent added in the mixing step a) is adjusted so as to obtain, at the end of this step and whatever the variant implemented, a mixture or a paste which does not flow, but which is also not too dry in order to allow its extrusion under suitable pressure conditions well known to those skilled in the art and dependent on the extrusion equipment used.

[0123] Preferably, said step b) of shaping by extrusion is carried out at an extrusion pressure greater than 1 MPa and preferably between 3 MPa and 10 MPa.

[0124] The loss on ignition of the material obtained after the shaping step, advantageously in the form of extrudates, tablets or balls, is between 30 and 40% by weight.

[0125] Step c) of maturation (optional)

[0126] The process for preparing said material according to the invention may comprise an optional step c) of maturation of the shaped material obtained at the end of step b). When implemented, said maturation step is advantageously carried out at a temperature of between 0 and 70°C, preferably between 10 and 60°C and preferably between 20 and 50°C, for a duration of between 1 minute and 72 hours, preferably between 30 minutes and 72 hours, and preferably between 1 hour and 48 hours and more preferably between 1 and 24 hours.

[0127] Preferably, said maturation step is carried out in air and preferably in humid air with a relative humidity between 20 and 100% and preferably between 70 and 100%. This step allows good hydration of the material necessary to limit the appearance of cracks which are detrimental to mechanical resistance.

[0128] The loss on ignition of the material shaped and matured after this stage is advantageously between 15 and 25% by weight.

[0129] Step d) drying (optional)

[0130] The process for preparing said material according to the invention may comprise a step d) of drying the shaped material obtained at the end of step b) or at the end of step c) when it is carried out. Said drying step, when it is carried out, is advantageously carried out at a temperature of between 0 and 200°C, preferably between 50 and 150°C and preferably between 70 and 150°C, for a duration of between 1 minute and 72 hours, preferably between 30 minutes and 72 hours, and preferably between 1 hour and 48 hours and more preferably between 1 and 24 hours.

[0131] The loss on ignition of the dried material obtained at this stage is advantageously between 7 and 10% by weight.

[0132] Optional calcination step

[0133] Advantageously, the shaped material resulting from step c) of maturation or d) of drying, can also optionally undergo a step d') of calcination at a temperature of between 200 and 600°C, preferably between 250 and 450°C for a duration of between 1 and 12 h and preferably between 1 and 4 h. This calcination step is particularly useful in order to eliminate the organic additives used in order to facilitate the shaping of the material.

[0134] Said optional calcination step d) is advantageously carried out under a gas flow comprising oxygen, for example preferably the extrudates are calcined under dry air or with different humidity levels or even temperature treated 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. Said calcination step d) may comprise a gradual increase in temperature and possibly a temperature plateau at a temperature between 100 and 200°C.

[0135] Step e) of hydrothermal treatment

[0136] The preparation process according to the invention comprises a step e) of hydrothermal treatment in the presence of water vapor of the material resulting from step b), c), d) or d').

[0137] The material shaped in step b), optionally matured in step c) and optionally dried / calcined in step d)), is subjected to hydrothermal treatment in the presence of water vapor and at a temperature between 200 and 550°C.

[0138] The hydrothermal treatment is carried out by any technique known to those skilled in the art. By hydrothermal treatment is meant contact at any stage of the preparation of the mixed support with water in the vapor phase or in the liquid phase. By hydrothermal treatment is meant in particular steam treatment or "steaming" according to the English terminology, autoclaving, calcination in humid air, rehydration. Without this reducing the scope of the invention, such a treatment has in particular the effect of making the silica component mobile.

[0139] In one embodiment, step e) of hydrothermal treatment may be carried out at atmospheric pressure, at a temperature between 200°C and 550°C, more preferably for a duration between 30 minutes and 5 hours. According to the invention, the hydrothermal treatment is a treatment containing water vapor and a gas, at temperature. The gas is advantageously air or nitrogen. The volume composition of the water in the gas may be between 20% and 100%, preferably 30% and 90%, very preferably between 40 and 70%.

[0140] The loss on ignition of the support obtained after this step is advantageously between 15 and 20% by weight.

[0141] In a preferred embodiment, said hydrothermal treatment step e) can totally or partially replace calcination step d) or f).

[0142] Step f) optional calcination

[0143] Advantageously, the shaped material resulting from step e) of hydrothermal treatment may also optionally undergo a step f) of calcination at a temperature of between 200 and 680°C, preferably between 400 and 660°C for a duration of between 1 and 12 h and preferably between 1 and 4 h, in one or more sequences. This calcination step may in particular be useful for releasing the microporosity of the chemisorbed residual water zeolite.

[0144] Said optional calcination step f) is advantageously carried out under a gas flow comprising oxygen, for example preferably the extrudates are calcined under dry air or with different humidity levels or even treated at temperature in the presence of a gas mixture comprising an inert gas, preferably nitrogen, and oxygen. The gas mixture used preferably comprises at least 5% volume, or even preferably at least 10% volume of oxygen.

[0145] The loss on ignition of the extrudates obtained after this step is advantageously between 1 and 10% by weight. At the end of steps a) to e) or a) to f) of the preparation process according to the invention, the material obtained, subsequently called “support”, is in the form of extrudates or pellets or tablets or beads.

[0146] However, it is not excluded that the said materials obtained are then, for example, introduced into equipment allowing their surface to be rounded, such as a drageoir or any other equipment allowing their spheronization.

[0147] Said catalyst supports according to the invention are composed of a KL-SiO2 zeolite composite material and have specific surfaces of between 80 and 200 rrï7g.

[0148] Said catalyst supports according to the invention have a total pore volume of between 0.35 and 0.6 cm 3 / g.

[0149] Said catalyst supports according to the invention have a macroporous volume of between 0.08 and 0.16 cm 3 / g.

[0150] Said catalyst supports according to the invention have a mesoporous volume of between 0.2 cm 3 / g and 0.4 cm3 / g.

[0151] Said catalyst supports according to the invention have a microporous volume of less than 0.07 cm 3 / g, and preferably greater than 0.03 cm 3 / g.

[0152] Said catalyst supports according to the invention have a sodium content of less than 0.2% by weight.

[0153] Said catalyst supports according to the invention have entirely satisfactory mechanical properties, in particular in terms of mechanical resistance,

[0154] In particular, said catalyst supports according to the invention have a mechanical resistance measured by the grain-to-grain crushing test, hereinafter denoted EGG 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.

[0155] The increase in mechanical strength makes it possible to envisage the use of said catalyst support in processes in the presence of water or solvents and at relatively high temperatures. Steps g), h), i) make it possible to obtain the catalyst according to the invention from the support obtained in step e) or f).

[0156] Step g): impregnation step

[0157] Said catalyst support according to the invention is impregnated by adding a metal from group VIII, preferably a noble metal of the Pt type. The impregnation is carried out by bringing said support into contact with an impregnation solution of precursor of the metal.

[0158] Preferably, the platinum precursor used is chosen from the following precursors without this list being limiting: hexachloroplatinic acid (H2PtCl6), bromoplatinic acid, ammonium chloroplatinate, platinum chlorides, platinum dichlorocarbonyl dichloride, platinum tetraamine chloride, platinum tetraamine nitrate (Pt(NH3)4Cl2) Pt(NH3)4(NO3) 2j or dihydroxyplatinediammine. Organic platinum complexes, such as platinum(II) diacetylacetonate, can also be used.

[0159] The precursor is diluted in aqueous phase to constitute the impregnation solution.

[0160] This metal can be introduced onto the support using a variety of techniques known to those skilled in the art, such as dry impregnation, excess impregnation, fluidized bed impregnation, pore filling impregnation, etc., preferably dry or excess impregnation. This step is carried out in such a way as to obtain excellent distribution and dispersion of the metallic phase.

[0161] Preferably, the following amounts of group VIII metal are introduced into step g) of the preparation process according to the invention:

[0162] 0.1% to 10% by weight, preferably from 0.2% to 5% by weight, more preferably from 0.3% to 2% by weight, and very preferably from 0.5% to 1.2% by weight, and even more preferably between 0.6 and 1.0% by weight of metal, preferably platinum, as a mass percentage measured relative to the total mass of final catalyst.

[0163] Step h) drying

[0164] The material thus obtained in step g) undergoes a drying step in order to remove the residual water from the porosity. This step can be carried out in a crossed bed, in a licked bed, in static mode, etc. Preferably, the temperatures used in this step are between 50°C and 200°C, preferably between 60°C and 150°C and very preferably between 80°C and 120°C. Step i) of calcination

[0165] The material thus obtained in step h) undergoes a calcination step necessary for the decomposition of the metal precursors, as well as for the good distribution and dispersion of the metal phase. This step is carried out under a gas flow of either air or air diluted with a neutral gas (N2, Ar, etc.). Preferably, this step can be carried out under a flow of pure air. Preferably, the temperatures used in this step can be between 200°C and 500°C, preferably between 250°C and 450°C and very preferably between 350°C and 420°C. Step i) can comprise a gradual increase in temperature and possibly a plateau at a temperature between 100 and 200°C.

[0166] Step i) of catalyst reduction

[0167] The material thus obtained in step i) may undergo a reduction step necessary for the activation of the metal precursors. This step is preferably carried out before contacting with the load, either prior to loading or in situ, under a gas flow of either pure hydrogen or hydrogen diluted with a neutral gas (N2, Ar, etc.). Preferably, the temperatures used in this step are between 300°C and 550°C, preferably between 350°C and 500°C and very preferably between 450°C and 500°C.

[0168] At the end of step i) or j), said catalysts according to the invention have specific surfaces of between 80 and 200 rrï7g, a microporous volume less than or equal to 0.04 cm 3 / g, more particularly between 0.015 and 0.04 cm 3 / g.

[0169] At the end of the preparation process according to the invention, the Cl contents on the catalyst are advantageously less than 0.5% and the Na content is less than 0.2% without there being any need to carry out washing.

[0170] Said catalysts according to the invention have metal contents, preferably platinum, of between 0.1 and 10%, preferably between 0.2 and 5%, very preferably between 0.3 and 2%, more preferably between 0.5 and 1.2%, very advantageously between 0.6 and 1.0% by weight of the anhydrous catalyst.

[0171] Said catalysts according to the invention have metal dispersions, in particular platinum, of between 50 and 70%. The catalyst obtained after deposition of group VIII metal, preferably platinum, by impregnation on the support is brought into contact with the gaseous feedstock to be treated in a reactor, which can be either a fixed bed reactor or a radial reactor.

[0172] The catalyst obtained at the end of the preparation process according to the invention can be used for catalysis applications, in particular the aromatization of C6 / C8 paraffinic cuts.

[0173] Such a catalyst is found in particular to have an activity and an aromatic yield for the aromatization of C6-C8 cuts, and in particular C6-C7, improved compared to the catalysts known to those skilled in the art. The process for preparing the catalyst according to the invention also has the advantage of reducing the environmental impact of the preparation of the catalysts, due to the non-use of halides and the disappearance of additional washing steps.

[0174] The invention is illustrated by the following examples which are in no way limiting.

[0175] EXAMPLES

[0176] Example 1: Preparation of a Pt / KL-SiO2 catalyst (comparative)

[0177] A support A is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Nyasil20) (30%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven and then calcined for 4 hours at 550°C.

[0178] Catalyst A is obtained by excess fluidized bed impregnation of this support. To do this, 25g of support are pre-calcined at 520°C for 2h in air, then deactivated with water by dropwise addition of water onto the rotating support in a drageoir. The precursors of Pt(NH3)4Cl2 and KNO3 are dissolved. The deactivated support is placed in the fluidized bed for fluidized bed impregnation. Fluidization is maintained for 24h at a rate of 25ml / min. After fluidization, the solution is withdrawn. The catalyst is then washed 4 times with 200ml of water in the fluidized bed for 30min at a rate of 25ml / min. The catalyst is dried in an oven at 120°C for 12 hours, first maintained at 150°C for 1 hour, then calcined: 250°C for 1 hour and 400°C for 2 hours. Table 1 below details the formulation and characteristics of catalyst A.

[0179] Table 1

[0180] Example 2: Preparation of a Pt / KL-SiO2 catalyst B (comparative)

[0181] A support B is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Siliaflash P60 40-63pm; Silicycle) (10%), a source of colloidal silica sol (20%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven and then calcined for 4 hours at 550°C.

[0182] Catalyst B is obtained by excess fluidized bed impregnation of this support. To do this, 25g of support are previously calcined at 520°C for 2h in air, then deactivated with water by adding water dropwise onto the rotating support in a drageoir. The precursors of Pt(NH3)4Cl2 and KNO3 are dissolved. The deactivated support is placed in the fluidized bed for fluidized bed impregnation. Fluidization is maintained for 24h at a rate of 25ml / min. After fluidization, the solution is withdrawn. The catalyst is then washed 4 times with 200ml of water in the fluidized bed for 30min at a rate of 25ml / min. The catalyst is dried in an oven at 120°C for 12 hours, first maintained at 150°C for 1 hour and calcined at 250°C for 1 hour and 400°C for 2 hours. Table 2 below details the formulation and characteristics of catalyst C.

[0183] Table 2

[0184] Example 3: Preparation of a C Pt / KL-SiO2 catalyst (comparative)

[0185] A support C is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Siliaflash P60 40-63pm; Silicycle) (10%), a source of colloidal silica sol (20%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven before hydrothermal treatment under a gas flow containing 50% by volume of water in air for 3 hours at 600°C. The extrudates are then calcined for 2 hours at 550°C.

[0186] Catalyst C is obtained by excess impregnation of this support in a fluidized bed. To do this, 25g of support are previously calcined at 520°C for 2h in air, then deactivated with water by adding water dropwise onto the rotating support in a drageoir. The precursors of Pt(NH3)4CI2 and KNO3 are dissolved. The deactivated support is placed in the fluidized bed for fluidized bed impregnation. Fluidization is maintained for 24h at a rate of 25ml / min. After fluidization, the solution is withdrawn. The catalyst is then washed 4 times with 200ml of water in the fluidized bed for 30min at a rate of 25ml / min. The catalyst is dried in an oven at 120°C for 12 hours, maintained at 150°C for 1 hour, then calcined at 250°C for 1 hour and 400°C for 2 hours.

[0187] Table 3 below details the formulation and characteristics of catalyst D.

[0188] Table 3

[0189] Example 4: Preparation of a Pt / KL-SiO2 catalyst D (according to the invention)

[0190] A support D is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3)) (70%), precipitated silica (Siliaflash C60 (5-20pm; Silicycle) (30%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven, calcined for 2 hours at 550°C before hydrothermal treatment under a gas flow containing 50% by volume of water in air for 3 hours at 500°C. The extruded catalysts are then calcined for 2 hours at 550°C. Catalyst D is obtained by dry impregnation of support D with a Pt(NH3)4CI2 solution. To do this, 50g of support are first calcined at 520°C for 2 hours in air, then placed in a closed vessel in a humid atmosphere, saturated with water.The precursor Pt(NH3)4Cl2 is put into aqueous solution. The Pt solution is added dropwise onto the rotating support in a dragee for 15 min. The catalyst is stored in a closed vessel for 24 hours, then dried in an oven at 120°C for 12 hours and calcined at 400°C.

[0191] Table 4

[0192] Example 5: Preparation of a Pt / KL-SiO2 catalyst E (according to the invention)

[0193] A support E is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Siliaflash C60 40-63pm; Silicycle) (5%), a source of colloidal silica sol (25%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The resulting paste is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven, dried at 120°C for 12 hours, calcined for 2 hours at 550°C before hydrothermal treatment under a gas flow containing 50% by volume of water in air for 3 hours at 500°C. The extrudates are then calcined for 2 hours at 550°C. Catalyst E is obtained by dry impregnation of support E with a Pt(NH3)4CI2 solution.To do this, 50g of support are previously calcined at 520°C for 2h in air, then placed in water saturation in a closed vessel under humid atmosphere. The precursor Pt(NH3)4Cl2 is put in aqueous solution. The Pt solution is added dropwise onto the rotating support in a drageoir for 15min. The catalyst is stored in a closed vessel for 24h, then dried in an oven at 120°C for 12h and calcined at 400°C.

[0194] Table 5

[0195] Example 6: Preparation of a Pt / KL-SiO2 catalyst (comparative)

[0196] A support F is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Siliaflash P60 40-63pm; Silicycle) (30%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven and then calcined for 4 hours at 550°C.

[0197] Catalyst F is obtained by dry impregnation of the support F with a Pt(NH3)4Cl2 solution. To do this, 50g of support are previously calcined at 520°C for 2h in air, then placed in water saturation in a closed vessel under humid atmosphere. The precursor Pt(NH3)4Cl2 is put in aqueous solution. The Pt solution is added dropwise onto the rotating support in a drageoir for 15 min. The catalyst is stored in a closed vessel for 24h, then dried in an oven at 120°C for 12h and calcined at 400°C.

[0198] Table 6 below details the formulation and characteristics of catalyst F.

[0199] Table 6

[0200] Example 7: Preparation of a G Pt / KL-SiO2 catalyst (comparative)

[0201] A support G is prepared by co-mixing a KL zeolite powder (TOSOH; Si / Al = 3) (70%), precipitated silica (Siliaflash P60 40-63pm; Silicycle) (30%), and methocel (K15M) (3% relative to the total mass of oxides) in a Brabender mixer. Water is added dropwise until a paste is obtained and mixing is continued for 20 minutes. The paste obtained is then extruded on an MTS piston extruder using a cylindrical die with a diameter of 1.6 mm. The extrudates are matured for 16 hours at 80°C in a ventilated oven before hydrothermal treatment under a gas flow containing 50% by volume of water in air for 3 hours at 600°C. The extrudates are then calcined for 2 hours at 550°C.

[0202] Catalyst G is obtained by dry impregnation of support F with a Pt(NH3)4Cl2 solution. To do this, 50g of support are first calcined at 520°C for 2 hours in air, then placed in water saturation in a closed vessel under a humid atmosphere. The precursor Pt(NH3)4Cl2 is put in aqueous solution. The Pt solution is added dropwise onto the rotating support in a drageoir for 15 min. The catalyst is stored in a closed vessel for 24 hours, then dried in an oven at 120°C for 12 hours and calcined at 400°C.

[0203] Table 7 below details the formulation and characteristics of catalyst G.

[0204] Table 7

[0205] Example 8: Flavoring a C6 / C7 cut

[0206] Approximately 1 g of the prepared catalysts A to G are loaded into a fixed bed reactor. Once loaded, the catalysts are dried under nitrogen flow at 150°C and then reduced under H2 flow at 470°C for 12 h. The temperature is then lowered to 400°C, and the charge is then injected.

[0207] The test is carried out at 4 bars and a temperature swept between 430 and 500°C, with a molar ratio of H2 / hydrocarbons of 4. The composition of the charge is presented in Table 8. The mass flow rate is 1 g charge. (g catalyst) 1 . h 1 .

[0208] Table 8

[0209] Table 9 below groups together the catalytic performance results of examples 1 to 7 corresponding to catalysts A to G.

[0210] The charge conversion is defined as follows:

[0211] Flow rates are expressed in g / h, concentrations are expressed in %wt.

[0212] Conversion i&nP6-P7= (1- (Output flow x (n-P6(%pds) + iso-P6(%pds) + n-P7(%pds) + iso- P7(%pds))output) / (Input flow x (n-P6(%pds) + iso-P6(%pds) + n-P7(%pds) + iso- P7(%pds))input) )x100

[0213] P6 and P7 respectively designate paraffins with 6 and 7 carbon atoms, n or iso.

[0214] The yield of Aromatics defined as follows:

[0215] Aromatic Yield = Output Flow x (A6 (%wt) + A7 (%wt) + A8(%wt)) / (Input Flow)

[0216] A6, A7, A8 denoting aromatics having 6, 7 and 8 carbon atoms respectively.

[0217] These conversions and efficiencies are measured at 480°C, and ppH = 1. Table 9

[0218] The comparative catalysts exhibit conversions that are at most 83.3% for catalyst A, and aromatic yields that are at most 75.6% for catalyst B.

[0219] Catalysts D and E, according to the invention, have much higher conversions, greater than 86%, or even 88%, and aromatic yields greater than 80%. Examples 1 to 8 above show in particular that the presence of all the steps of the process according to the invention, in particular a step of hydrothermal treatment of the support under the required conditions, is essential to improve the performances and bring them beyond 86% conversion of P6P7 and 80% for the yield of Aromatics.

Claims

CLAIMS 1. Process for preparing an aromatization catalyst comprising at least 70% by weight of zeolite KL, a refractory oxide of silica type SiO2 and a metal of group VI II B, comprising at least the following steps: a) a step of mixing at least one source of zeolite KL of structural type LTL, at least one source of silica SiO2, with at least one solvent chosen from water, physical solvents and chemical solvents, optionally in the presence of an organic adjuvant to obtain a mixture, b) a step of shaping, preferably by extrusion, the mixture obtained at the end of step a), c) an optional step of maturing the shaped material at a temperature between 0 and 70°C, for a period between 1 minute and 72 hours, in air, preferably in humid air with a relative humidity between 20 and 100%;d) an optional drying step of the shaped and optionally matured material at a temperature of between 0 and 200°C, for a duration of between 1 minute and 72 hours; optionally followed by calcination d') at a temperature of between 200 and 600°C, preferably between 250 and 450°C for a duration of between 1 and 12 h and preferably between 1 and 4 h; e) a step of hydrothermal treatment of the material shaped in step b), optionally matured and optionally dried / calcined, in the presence of water vapor, at a temperature of between 200 and 550°C, preferably under atmospheric pressure and for a duration of between 30 minutes and 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 between 200 and 680°C, preferably between 400 and 660°C for a duration of between 1 and 12 h and preferably between 1 and 4 h, to obtain a calcined catalyst support; g) a step of impregnation of a metal from group VIII, preferably platinum, by bringing the support obtained at the end of step e) or f) into contact with a solution of a precursor of said metal dissolved in the aqueous phase, such that the metal content on the catalyst is between; between 0.1% to 10% by weight, preferably from 0.2% to 5% by weight, preferably from 0.3% to 2% by weight, and very preferably from 0.5% to 1.2% by weight relative to 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 between 50°C and 200°C; i) a step of calcining the dried material obtained at the end of step h) under a gas flow of either pure air or air diluted with a neutral gas between 200°C and 500°C, preferably between 250°C and 450°C and very preferably between 350°C and 420°C, to obtain a calcined catalyst.

2. Preparation process according to claim 1 comprising: j) a step of reducing the calcined catalyst obtained at the end of step i) carried out before contacting with the feedstock, by contacting with a flow of gas containing hydrogen, pure or diluted with a neutral gas, at a temperature between 300°C and 550°C, preferably between 350°C and 500°C and very preferably between 450°C and 500°C.

3. Preparation process according to one of the preceding claims, in which step a) is carried out by mixing at room temperature, for a period of between 5 and 60 min, and preferably between 10 and 50 min.

4. Preparation process according to one of claims 1 to 3, in which the zeolite KL and the silica SiO2 are introduced in step a) as a mixture of oxides in the following proportions: -70% to 90% by weight, preferably 70% to 85% by weight of at least one KL zeolite, - 10 to 30% by weight, preferably 15 to 30% by weight of at least one source of silica SiO 2 ; and we add to the mixture: - 10 to 30% by weight of solvent, relative to the total weight of said mixture of oxides; - 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 of at least one organic adjuvant, relative to the total weight of said mixture of oxides; the sum of the contents of each of the compounds introduced at this stage being equal to 100%.

5. Preparation process according to one of the preceding claims in which a single source of silica is used in step a), preferably a precipitated silica or a silica gel, very preferably a precipitated silica.

6. Preparation process according to one of claims 1 to 4 in which two different sources of silica are used in step a).

7. Preparation process according to claim 6 wherein the two sources of silica are a precipitated silica and a colloidal silica sol.

8. Preparation process according to one of claims 5 to 7 in which the silica used in step a) has a grain size or particle size of less than 100 pm, and preferably less than 80 pm, more preferably less than 60 pm, even more preferably less than 20 pm, or even less than 10 pm for precipitated silica or silica gel and between 5 and 200 nm, preferably between 15 and 50 nm for colloidal silica sol.

9. Preparation process according to one of the preceding claims in which the organic adjuvant is chosen from cellulose derivatives, polyethylene glycols, aliphatic monocarboxylic acids, alkylated aromatic compounds, sulphonic acid salts, fatty acids, polyvinyl pyrrolidone, polyvinyl alcohol, methylcellulose, polyacrylates, polymethacrylates, polyisobutene, polytetrahydrofuran, starch, polysaccharide-type polymers, scleroglucan, hydroxyethylated cellulose-type derivatives, carboxymethylcellulose, lignosulfonates and galactomannan derivatives, taken alone or as a mixture, preferably carbomethylcellulose.

10. Preparation process according to one of the preceding claims in which the support obtained at the end of step e) or f) has a specific surface area of ​​between 80 and 200 m 2 / g, a total pore volume between 0.35 and 0.6 cm 3 / g, a macropore volume between 0.08 and 0.16 cm 3 / g, a mesoporous volume between 0.2 cm 3 / g and 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 resistance measured by the grain-to-grain crushing test, subsequently noted EGG, 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.

11. Aromatization catalyst support in the form of a KL-SiO2 zeolite composite material comprising at least 70% of KL zeolite, obtained in step e) or f) of the process according to one of the preceding claims, having a specific surface area of ​​between 80 and 200 m2 / g, a total pore volume of between 0.35 and 0.6 cm 3 / g, a macropore volume between 0.08 and 0.16 cm 3 / g, a mesoporous volume between 0.2 cm 3 / g and 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 resistance measured by the grain-to-grain crushing test, subsequently noted EGG, 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.

12. Aromatization catalyst for C6-C8 paraffinic cuts capable of being prepared according to one of claims 1 to 10 comprising at least 70% by weight of KL zeolite of LTL structural type having a Si / AI ratio of between 2.8 and 4, preferably between 2.8 and 3.5, between 10 and 30% by weight of a refractory oxide of silica type SiO2, a metal of group VI 11 B, preferably platinum, said catalyst further having a specific surface area of ​​between 80 and 200 rrï7g, a microporous volume of less than 0.04 cm3 / g, a content of metal from group VII IB, between 0.1 and 10%, preferably between 0.2% and 5% by weight, very preferably between 0.3% and 2% by weight, and even more preferably from 0.5% to 1.2% by weight of metal and a dispersion of said metal between 50 and 70%.

13. Aromatization catalyst according to claim 12 wherein the metal is platinum and the platinum content is between 0.6 and 1.0% by weight relative to the total weight of catalyst.

14. Aromatization catalyst according to one of claims 12 to 13 in which the KL zeolite content is between 70 and 85% by weight and the refractory oxide content is between 15 and 30% by weight, the sum of all the constituents of the catalyst including the metal being equal to 100%.

15. Process for aromatizing at least one alkane or cycloalkane contained in a hydrocarbon feedstock comprising C6-C8 paraffinic cuts by bringing the catalyst prepared according to one of claims 1 to 10 or according to one of claims 12 to 14 into contact with the gaseous feedstock to be treated in the presence of hydrogen, said process being carried out in the vapor or liquid phase, at a temperature between 400°C and 550°C, at a pressure between 2 and 20 MPa, at a molar ratio of hydrogen to hydrocarbon compounds between 1 and 10, at an hourly mass flow rate PP H between 1 and 10 h' 1 .

16. Aromatization process according to claim 15 having a conversion of n and iso paraffins to C6-C7 greater than or equal to 85% and an aromatic yield greater than or equal to 80%.

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