CN101134171B - C8Process for preparing catalyst for isomerization of aromatic hydrocarbon - Google Patents

Abstract

C₈A preparation method of an aromatic hydrocarbon isomerization catalyst comprises the steps of mixing and molding an EUO type molecular sieve and a binder to obtain a carrier, introducing VIII group metals, drying, roasting, and reducing by using reducing gas to obtain the catalyst, wherein the catalyst contains 5-90 mass% of the EUO type molecular sieve, 10-90 mass% of the binder and 0.1-5.0 mass% of the VIII group metals, the preparation method of the EUO type molecular sieve comprises the steps of mixing and uniformly stirring a compound containing an element X, a compound containing an element T or a compound containing both the elements X and T, an alkali metal compound and water, carrying out hydrothermal crystallization reaction in the presence of a template agent precursor prepared from crude dibromoalkane and monoamine, collecting solids and drying, wherein the X is selected from silicon or germanium, the T is selected from aluminum, iron, gallium or boron, the crude dibromoalkane is a mixture of dibromoalkane, monobromosol and alkane diol, wherein the dibromoalkane content is 80-95 mass%. The catalyst prepared by the method has higher ethylbenzene conversionConversion rate and lower aromatic hydrocarbon loss rate.

Description

A kind of preparation method of C8 aromatic hydrocarbon isomerization catalyst

technical field

The invention relates to a preparation method of a _C8 aromatic hydrocarbon isomerization catalyst, specifically, a preparation method of a catalyst using EUO type molecular sieve as the catalyst acid component.

Background technique

The EUO structure molecular sieve has a one-dimensional network microporous structure, and its skeleton is a ten-membered ring channel composed of silicon-oxygen and aluminum-oxygen tetrahedrons, with elliptical openings and a diameter of 0.41nm×0.57nm. There is a cage structure on the side of the main channel of the molecular sieve, the depth of the cage is 0.81nm, and the diameter of the cage opening is 0.68nm×0.58nm. Since the EUO molecular sieve has such a special structure, good dispersibility to metals, and high mechanical strength, the catalyst using the EUO molecular sieve as the acidic component of the catalyst shows good isomerization performance of aromatics.

US4537754 discloses a EU-1 type molecular sieve and its synthesis method. Using the alkylated derivatives of polymethylene α-ω-diamine ions or their precursors as templates, uniformly mix silicon sources, aluminum sources, alkali metal compounds, templates and water, and then hydrothermally crystallize The precursor of the template agent is a parent diamine and an alcohol or an alkyl halide. The SiO ₂ /Al ₂ O ₃ molar ratio of the synthesized EU-1 molecular sieve is 10-500.

US6514479 discloses an EUO type molecular sieve with a particle size of less than 5 μm and 90% of the aggregated particle size is less than 200 μm-40 nm and a synthesis method. The method uses ultrasonic treatment to reduce the size of the aggregated particles. Compared with ordinary EUO molecular sieves, the above-mentioned molecular sieves with small aggregate sizes have higher activity and conversion rate of ethylbenzene. In this method, EUO molecular sieves use polymethylene α-ω-diamine alkyl derivatives or their precursors dibromohexane and trimethylamine as templates, and silicon sources, aluminum sources, alkali metals, templates and The selected seed crystals are evenly mixed and hydrothermally crystallized to synthesize a silica-alumina molecular sieve with an EUO structure.

US6342200 reported that polymethylene α-ω-diamine alkyl derivatives were used as templates, and silicon sources, aluminum sources, alkali metal compounds and templates were formed by adding molecular sieves with structures different from the EUO type as seeds. A method for the synthesis of EUO type molecular sieves by hydrothermal crystallization of the mixture.

CN99127713.9 discloses a kind of method for preparing EUO type structure zeolite, this method adopts template agent precursor to synthesize zeolite, and its used precursor is monoamine and dihaloalkane or alkane diol, then adopts trimethylamine and dihaloalkane diol in the example Hexyl bromide is used as template precursor to prepare EUO-type zeolite, and seed crystals can be added during synthesis to shorten the reaction time, but the reaction time without seed crystals is longer, generally exceeding 100 hours.

US6723301 discloses a kind of EUO type molecular sieve with low nitrogen content, this molecular sieve uses the benzhydryl dimethylamine and its derivatives of low consumption as template agent, in silicon source, aluminum source, alkali metal compound, template agent and In the homogeneous mixture system formed by seed crystals, silicon-aluminum molecular sieves with EUO structure with a Si/Al molar ratio of 7-26 are synthesized by hydrothermal crystallization.

US6616910 uses benzhydryl dimethylamine and its derivatives as templates, and by adding EUO molecular sieves as seed crystals, the reaction mixture formed by uniformly mixing silicon source, aluminum source, alkali metal compound, template agent and seed crystals , through hydrothermal crystallization, the EUO structure molecular sieve with Si/Al molar ratio of 5-50 was synthesized. In this patent example, the _C8 aromatics isomerization catalyst prepared with hydrogen EU-1 molecular sieve as acidic component contains 10% by mass of HEU-1 molecular sieve, 89.7% by mass of alumina, and a Pt loading of 0.3% by mass. HEU-1 The Si/Al ratio of the molecular sieve is 26, and the Na ₂ O content in the molecular sieve is 0.54% based on the HEU-1 molecular sieve. The catalyst is subjected to reduction and presulfurization treatment before reaction, and the molar ratio of sulfur/metal on the surface is 1.5. Under the conditions of 390°C, total reaction pressure 1.5MPa, and hydrogen partial pressure 1.2MPa, the isomerization reaction of C ₈ aromatics was carried out, the conversion rate of ethylbenzene was 40.1% by mass, the loss of aromatics was 3.36% by mass, and the p-xylene content in the product was about 90.5% by mass of its thermodynamic equilibrium value.

Among the catalysts with higher _C8 aromatic hydrocarbon isomerization performance described in the above prior art, the active component EUO type molecular sieves all use expensive templates in the preparation process, so the catalyst production cost is higher, which limits the use of EUO type molecular sieves. Type molecular sieves are used for large-scale production and application of acidic components of catalysts.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a catalyst for isomerization of _C8 aromatics, the catalyst prepared by the method has good isomerization performance of _C8 aromatics, and the preparation cost is low.

The preparation method of the _C8 aromatic hydrocarbon isomerization catalyst provided by the present invention comprises mixing EUO type molecular sieve and binder to form a carrier, then introducing Group VIII metal into the carrier, drying and calcining, and reducing with reducing gas A catalyst is prepared, which contains 5-90% by mass of EUO-type molecular sieve, 10-90% by mass of binder and 0.1-5.0% by mass of Group VIII metal, wherein the preparation method of EUO-type molecular sieve includes Mix the compound containing element X, the compound of element T, or the compound containing both elements X and T with the alkali metal compound and water and stir evenly, and carry out water in the presence of a template precursor made of crude dibromoalkane and monoamine. Thermal crystallization reaction, drying after collecting the solid, the X is selected from silicon or germanium, T is selected from aluminum, iron, gallium or boron, and the crude dibromoalkane is dibromoalkane, monobromoalcohol and alkane di A mixture of alcohols, wherein the dibromoalkane content is 80-95% by mass.

The EUO type molecular sieve used in preparing the catalyst in the method of the present invention is synthesized by using crude dibromohexane and monoamine as template precursors, which not only expands the source of the template used in molecular sieve synthesis, but also reduces the synthesis cost. The catalyst prepared by using the EUO type molecular sieve synthesized by this method as an active component is used for the isomerization reaction of C ₈ aromatics, and has higher p-xylene selectivity, lower loss of aromatics, and higher conversion rate of ethylbenzene.

Description of drawings

Fig. 1 is the X-ray diffraction spectrum of EUO molecular sieve, the active component of the catalyst of the present invention.

Detailed ways

The method of the invention adopts a cheap template agent precursor to synthesize EUO type molecular sieve, and then mixes it with a binder to obtain a carrier, and introduces a group VIII metal component into the carrier to obtain a catalyst. The template agent precursor used in the synthesis of EUO type molecular sieve is a mixture of crude dibromoalkane and monoamine, and the crude dibromoalkane is prepared after bromination of alkanediol, most of which are dibromoalkane, The rest is unreacted alkanediol and monobromoalcohol, and these three substances can react with monoamine to generate polymethylene diamine ion and become template agent. Since the crude dibromoalkane is synthesized from the cheap and easy-to-obtain alkanediol as a raw material, its preparation is simple and easy, which not only shortens the crystallization time of EUO molecular sieve synthesis, but also stabilizes the structure and properties of the prepared molecular sieve. The structure and properties of the molecular sieve prepared by this method are stable, and the catalyst prepared by it is used for the isomerization of C ₈ aromatics. Under the condition that the loss of xylene is as little as possible, the composition of the reaction product can be approached to the thermodynamic equilibrium to the greatest extent, and the Ethylbenzene conversion.

The crude dibromoalkane consists of 0.5-10% by mass of C ₄ -C ₈ alkane diol, 8-20% by mass of C ₄ -C ₈ monobromoalcohol and 80-90% by mass of C ₄ -C The dibromoalkane composition of ₈ is preferably composed of 0.5 to 10% by mass of hexanediol, 8 to 20% by mass of monobromohexanol and 80 to 90% by mass of dibromohexane.

The crude dibromoalkane is prepared by the following method: alkanediol and hydrogen bromide are fully reacted at reflux temperature in the presence of an acidic catalyst, and then the oil phase is washed with an alkali solution. The molar ratio of hydrogen bromide to alkanediol is 2-6:1, the acidic catalyst is concentrated sulfuric acid, the alkali solution is preferably sodium hydroxide solution, and its concentration is preferably 2-10% by mass.

The monoamine is a tertiary amine whose substituent is C ₁ -C ₃ alkyl, preferably trimethylamine.

The ratio of the monoamine to the total moles of substances contained in the crude dibromoalkane is 2.0-2.5:1.

The method of the present invention selects crude dibromoalkane and monoamine as template precursors, adds the precursors into the reaction raw materials, and carries out hydrothermal crystallization reaction under alkaline conditions, during which the template precursors are generated Template agent, and the reaction raw materials are crystallized under the guidance of the template agent to generate molecular sieves with the desired structure.

In the method of the present invention, if the compound containing X and the compound containing T are selected from different compounds, the more preferred method is: first uniformly mix the compound containing element X and an appropriate amount of water to prepare a mixture; then mix the compound containing element T The compound is uniformly mixed with an appropriate amount of water to prepare a mixture; the two mixtures and the template precursor of the present invention are uniformly mixed to obtain a reaction mixture.

The molar ratio of each material in terms of oxides in the reaction mixture is:

XO ₂ /T ₂ O ₃ 5～150

OH ^- /XO ₂ 0.03～1.5

R/XO ₂ 0.02～0.7

M ₂ O/XO ₂ 0.015～0.8

H ₂ O/XO ₂ 1～300

The preferred molar ratio of each material in the reaction mixture is:

XO ₂ /T ₂ O ₃ 8～130

OH ^- /XO ₂ 0.05～1.3

R/XO ₂ 0.08～0.6

M ₂ O/XO ₂ 0.025～0.65

H ₂ O/XO ₂ 5～250

Among them, T ₂ O ₃ represents a compound containing aluminum, iron, gallium or boron as an oxide, XO ₂ represents a compound containing silicon or germanium as an oxide, and R is the total amount of each substance contained in the crude dibromoalkane. The number of moles, M is an alkali metal. The reaction mixture is hydrothermally crystallized at 120-200° C. for 6-350 hours. After the crystallization is completed, the resultant is rapidly cooled to 15-30° C., filtered and washed to obtain a solid product. The product is dried and calcined to obtain EUO type molecular sieve. If not calcined, water-containing EUO molecular sieves can be obtained. The drying temperature is preferably 80-120°C, the suitable calcination temperature is 500-600°C, and the calcination time is preferably 6-30 hours.

The silicon-containing compound is preferably silicon dioxide, silica gel, water glass or silicate, and the aluminum-containing compound is sodium aluminate, aluminum sulfate, aluminum nitrate, alkoxy aluminum compound, aluminum oxide, aluminum hydroxide colloid, pseudothin Boehmite or boehmite, the boron-containing compound is preferably boric acid, the gallium-containing compound is preferably gallium oxide, and the alkali metal compound is preferably sodium hydroxide.

In the method, a compound containing both elements X and T can be selected as a raw material to prepare molecular sieves. The preferred compound is amorphous silica-alumina, and the molar ratio of silica/alumina is 6-18, preferably 8-15.

The EUO type molecular sieve prepared by the method of the present invention is preferably a silica-alumina molecular sieve, the molar ratio of SiO ₂ /Al ₂ O ₃ is 5-130, and the adsorption amount of NH ₃ is 0.1-1.5 mmol/g.

The EUO-type molecular sieve prepared by the present invention is mixed with a binder and molded into a carrier, and then a VIII group metal is introduced into the carrier to obtain a catalyst. The catalyst needs to be reduced before use, and passivation treatment is preferably carried out after reduction .

The binder is selected from alumina, aluminum hydroxide, aluminum sol, silica sol or silica-alumina sol, preferably aluminum hydroxide, such as pseudo-boehmite and boehmite. If the binder is selected from the mixture of the above-mentioned aluminum-containing compound and silicon dioxide, silica gel or silica-alumina gel, the content of silica, silica gel or silica-alumina gel in the mixture is 5-75% by mass.

During the molding process of the catalyst, extrusion aid and peptizing agent are preferably added to the molecular sieve and the binder. Said extrusion aid is preferably squash powder, peptizer is preferably dilute nitric acid or hydrochloric acid, and the suitable concentration is 1-8% by volume. The extrusion aid is preferably 0.5-9.0% by mass of the total amount of solid raw materials, and the peptizer is preferably 20-80% by mass of the total amount of solid raw materials.

The EUO type molecular sieve contained in the catalyst prepared by the present invention is preferably hydrogen type. When the EUO type molecular sieve is sodium type, it is preferably converted into a hydrogen type molecular sieve by ion exchange method and then mixed with a binder to form a carrier. It is also possible to mix the sodium-type EUO-type molecular sieve with the binder and form it first, and then convert the EUO-type molecular sieve into a hydrogen-type, and the conversion method is preferably an ion exchange method.

The method of converting sodium-type molecular sieves or sodium-type molecular sieves in the carrier into hydrogen-type by ion exchange method is: immerse the molecular sieves or carriers in acid or ammonium salt solution for ion exchange. The ion exchange is preferably carried out under continuous stirring conditions. The exchange temperature The temperature is preferably 60-100°C, and the time is preferably 0.5-4.0 hours. The solid obtained after the exchange is dried and calcined to obtain the hydrogen molecular sieve. The drying temperature is preferably 80-120°C, the calcination temperature is preferably 500-600°C, and the calcination time is preferably 4-8 hours. The ion exchange can be carried out several times until the sodium content in the molecular sieve or carrier is 0.005-0.5% by mass.

The ammonium salt used for ion exchange is preferably ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium carbonate or ammonium bicarbonate. In addition to ammonium salt, ammonia water can also be used for ion exchange. The acid used for ion exchange is preferably hydrochloric acid, nitric acid or sulfuric acid. The concentration of NH ₄ ⁺ or H ⁺ contained in the exchange solution is preferably 1 to 10% by mass. The liquid/solid mass ratio during ion exchange is preferably 1-10:1.

In the method of the present invention, the Group VIII metal is preferably introduced into the carrier by impregnation. During the impregnation, the impregnating solution is first formulated with a compound containing Group VIII metals, and then the carrier is impregnated with the impregnating solution, and then the impregnated solid is dried and calcined to obtain the catalyst in an oxidized state. The immersion temperature is preferably 15-100° C., the time is preferably 0.5-168 hours, and the liquid/solid volume ratio during immersion is preferably 0.8-2.5:1. The drying temperature is preferably 80-120° C., the calcination temperature is preferably 500-600° C., and the time is preferably 4-8 hours.

The compound containing VIII group metal is preferably platinum or palladium nitrate, halide, ammonium complex, acetate, halide acid compound, halide acid ammonium salt, carbonyl compound or hydroxyl compound, such as platinum nitrate, palladium nitrate, Platinum chloride, palladium chloride, chloroplatinic acid, chloropalladic acid, ammonium chloropalladate, ammonium chloroplatinate, palladium carbonyl halide, platinum carbonyl halide, hexahydroxypalladium acid, or hexahydroxyplatinic acid.

Oxidized catalysts need to be reduced before use, and the reduction conditions are normal pressure, 250-600°C. The reducing gas used for the reduction is preferably hydrogen, carbon monoxide or methane, and the time is preferably 0.5 to 6.0 hours.

The reduced catalyst is preferably passivated before use. The passivation method is to treat the reduced catalyst with a reducing gas containing sulfide, carbide or ammonia. The passivation temperature is preferably 250-600°C, and the passivation time is preferably 0.5 ~24 hours. The sulfide used for passivation is preferably hydrogen sulfide or thioalkane, and the carbide is preferably sulfide carbide, C ₄ -C ₇ alkane, C ₄ -C ₇ olefin or C ₆ -C ₉ aromatic hydrocarbon. After passivation, the molar ratio of sulfur, ammonia or carbon on the surface of the catalyst to surface metal elements is 0.2-6.0.

The catalyst prepared by the method provided by the invention is suitable for the isomerization reaction of _C8 aromatics, the reaction temperature is 300-500°C, preferably 350-430°C, the total reaction pressure is 0.4-2.0MPa, preferably 0.6-1.5MPa, and the hydrogen partial pressure is 0.5 to 1.5 MPa, preferably 0.6 to 1.2 MPa, and the mass space velocity of the feed during the reaction is preferably 0.2 to 30 hours ^-1 , more preferably 1 to 10 hours ^-1 .

The present invention is further illustrated by examples below, but the present invention is not limited thereto.

The X-ray diffraction detection of the samples in the examples is determined by a Siemens D5005 diffractometer. The experimental conditions are: X-ray source CuKα, 0.154056 nm, tube voltage 30 kV, tube current 20 mA, filter is Ni, scan rate is 4°/min, step size is 0.02°.

Relative crystallinity of the sample: the ratio of the sum of the diffraction intensities of the characteristic peaks in the XRD spectrum of the tested molecular sieve to the sum of the diffraction intensities of the characteristic peaks in the XRD spectrum of the standard molecular sieve.

The relative crystallinity of the sample = (Ii/I) × 100%

The sum of the diffraction intensities of each characteristic peak in the XRD spectrogram of Ii-measured molecular sieve in the formula,

The sum of the diffraction intensities of each characteristic peak in the XRD spectrum of the I-standard sample molecular sieve.

The _NH3 adsorption capacity of the samples was determined by the temperature-programmed desorption method.

Experimental method: (1) 200 mg of sample was roasted in the above-mentioned device in air at 540° C. and normal pressure for 4 hours, then lowered to 150° C. in nitrogen and continued to be purged with nitrogen for 1 hour. (2) Nitrogen gas with an NH ₃ content of 10% by volume was introduced at 150° C. to contact with the sample for 3 hours to perform NH ₃ adsorption. (3) Purging with nitrogen gas for 2 hours. (4) When performing temperature-programmed desorption at a heating rate of 5°C/min, use a thermal conductivity detector to record the desorption peak of NH ₃ . The _NH3 adsorption amount of the samples was calculated according to the _NH3 desorption peak area.

Example 1~5

The following examples use the method of the present invention to prepare EUO type molecular sieves.

(1) Preparation of template precursor

In the four-neck flask equipped with reflux condenser, stirrer, thermometer and dropping funnel, first add 100g of hexanediol (Beijing Chemical Reagent Company, chemically pure, content ≥ 99% by mass) and 75g of hydrogen bromide ( Sinopharm Group Chemical Reagent Co., Ltd., analytically pure, content ≥ 99% by mass), stirred at 25°C to fully dissolve the two, heated to 40°C, and slowly added 100g of concentrated sulfuric acid (Beijing Chemical Plant, chemically pure, 95 ~98% by mass), then add 200g of hydrogen bromide, slowly heat up to reflux temperature and react for 4 hours, wash the oil phase with an equal volume of water and 5% by mass of sodium hydroxide solution to make it neutral, and obtain the crude dihydrogen bromide Hexyl bromide, which contains 85% by mass of dibromohexane, 13% by mass of monobromohexanol and 2% by mass of hexanediol. The composition of the crude dibromohexane was analyzed by HP5890 chromatography and Agilent DB-1 chromatographic column. Analysis conditions: inlet temperature 250°C, detector temperature 300°C, column oven 50-260°C, heating rate 10°C/min.

The above-mentioned crude dibromohexane and trimethylamine solution (Beijing Jinlong Chemical Reagent Company, 33% by mass) were made into the template agent precursor N according to the ratio of the total molar number of each substance in trimethylamine to crude dibromohexane 2.5:1. .

(2) Preparation of molecular sieve

Silica sol (produced by Wenzhou Catalyst Factory, silicon dioxide content 29.2% by mass) and deionized water are uniformly mixed to form a mixture, then sodium aluminate (produced by Tianjin Jinke Fine Chemical Research Institute, 45% by mass of aluminum oxide content) %, sodium oxide content 33% by mass), sodium hydroxide and deionized water are uniformly mixed to form a mixture. Mix the above two mixtures and template N evenly, transfer them to an autoclave, let stand at 180°C for crystallization for 96 hours, cool to room temperature, filter and wash the solid product, dry at 110°C for 2 hours, and bake at 550°C EU-1 molecular sieves were obtained in 10 hours. The amount of raw materials in each example, the molar ratio of feed intake and the properties of the synthetic EU-1 molecular sieve are shown in Table 1. In Table 1, R is the total molar number of each substance in the thick dibromohexane, and the X-ray diffraction pattern of the molecular sieve prepared by Example 1 is shown in Table 1. figure 1.

Comparative example 1

Prepare EUO molecular sieve according to USP6 514 479 method.

Mix silica sol and deionized water evenly to make a mixture; mix sodium aluminate, sodium hydroxide and deionized water evenly to make a mixture; mix the above two mixtures and template bromide 1,6-N,N,N , N', N', N'-hexamethylhexamethylenediamine (produced by Fluca Company) was transferred to an autoclave until it was uniform, and it was left to crystallize at 180°C for 96 hours, cooled to room temperature, filtered and washed to obtain a solid The product was dried at 110°C for 2 hours and calcined at 550°C for 10 hours to obtain EUO-type silica-alumina molecular sieve D. The amount of raw materials used in the preparation process, the molar ratio of feed and the properties of the synthesized EU-1 molecular sieve are shown in Table 1.

Example 6

The following examples prepare C ₈ aromatics isomerization catalysts.

(1) Kneading molding: get 45.00 grams of molecular sieve D ₁ prepared in Example 1, 45.94 grams of pseudo-boehmite powder (produced by Wenzhou Catalyst Factory, Al ₂ O ₃ content is 76.3% by mass), 5 grams of Selina powder and 30 ml 2% by volume of dilute nitric acid solution is mixed evenly, and kneaded to make strip-shaped particles.

(2) Ion exchange: Take 50 g of the particles prepared in step (1) and 250 ml of 5 mass % ammonium chloride aqueous solution at 90° C. for 2 hours under continuous stirring, and exchange 2 times in total. The sodium content in the carrier after ion exchange was 0.04% by mass. The particles after ion exchange were dried at 110° C. for 12 hours, and calcined at 550° C. for 4 hours to obtain a carrier.

(3) loaded metal elements: get 30 grams of the carrier obtained after the ion exchange in step (2), add it to 50 milliliters of chloroplatinic acid solution with a concentration of 3.36 mg/ml at 25 ° C for 36 hours, and dry at 110 ° C for 8 hours. Calcined at 580°C for 8 hours to obtain catalyst E ₁ in oxidation state, whose composition and platinum dispersion are shown in Table 2.

(4) Reduction passivation: the particles prepared in step (3) were treated at 300° C. and normal pressure under the condition of H ₂ flow rate of 100 ml/min for 3 hours, and then treated with 30% by mass H ₂ S Hydrogen treatment for 3 hours. The S/Pt molar ratio on the catalyst surface after passivation was 1.5.

Example 7

Get the EUO type molecular sieve that 33.50 grams example 2 prepares, the hydrated aluminum oxide of 66.42 grams (Beijing Chemical Reagent No. 2 factory, content 65 mass %), 5 grams of silica gel (Shenyang Chemical Co., Ltd. production), 40 milliliters 3 volume % dilute nitric acid The solution is mixed evenly and kneaded to form strip-shaped particles.

Get 50 grams of strip-shaped particles according to the method of Example 6 (2) step, perform ion exchange, dry, and roast to obtain a carrier, and the sodium content in the carrier is 0.045% by mass. Catalyst _E2 is prepared by the method of step (3), except that at 22°C, the carrier is added to 65 milliliters of palladium nitrate solution with a concentration of 4.38 mg/ml and soaked for 44 hours, dried and calcined to obtain catalyst _E2 . The composition and platinum dispersion are shown in Table 2.

Treat the particles prepared in step (3) at 400°C and normal pressure with nitrogen containing 50 vol% H ₂ at a flow rate of 100 ml/min for 4 hours, and then treat it with nitrogen containing 0.07 vol% CS ₂ 24 hours. The S/Pa molar ratio of the catalyst surface after passivation was 1.8.

Example 8

Get 45.00 grams of molecular sieve D3 prepared in Example ₃ , 45.94 grams of silica-alumina gel (Fushun Catalyst Factory, alumina content 67%, silicon oxide content 33% by mass), 5 grams of turnip powder, and 35 ml of 2% by volume hydrochloric acid and mix Uniform, kneaded into strip particles.

Get 50 grams of strip-shaped particles according to the method of Example 6 (2) step, perform ion exchange, dry, and roast to obtain a carrier, and the sodium content in the carrier is 0.04% by mass. Catalyst _E3 is prepared by the method of (3), the difference is that the support is added to 50 milliliters of concentrations and is 3.36 mg/ml of chloroplatinic acid solution and soaked for 36 hours, and the composition and platinum of the catalyst _E3 obtained after drying and roasting See Table 2 for dispersion.

The particles prepared in step (3) _were treated with H at a flow rate of 40 ml/min at 350°C and normal pressure for 5 hours, cooled to 250°C, and treated with _N containing 5.0% NH by volume for ₁₆ hours. The molar ratio of NH ₃ /Pt on the surface of the catalyst after passivation is 2.0.

Example 9

9.50 g of molecular sieve D ₄ prepared in Example 4, 90.40 g of pseudoboehmite powder, 5 g of scallop powder, and 30 ml of 4% by volume nitric acid aqueous solution were uniformly mixed, and kneaded to form strip-shaped particles.

Get 50 grams of bar-shaped particles and carry out ion exchange with 200 ml of 4 mass % nitric acid aqueous solution at 80 ° C for 2 hours under continuous stirring, and exchange 2 times in total. The sodium content in the particles is 0.052 mass %. The particles were dried at 110° C. for 24 hours and calcined at 580° C. for 4 hours to obtain a carrier.

Take 30 grams of carrier, add it to 29 milliliters of chloroplatinic acid solution with a concentration of 5.21 mg/ml at 24 ° C for 24 hours, dry at 110 ° C for 8 hours, and roast at 560 ° C for 8 hours. The composition and platinum dispersion of the obtained catalyst _E4 See Table 2 for the degree.

Catalyst _E4 was reduced at 350°C under normal pressure in _H2 with a flow rate of 60ml/min for 5 hours, and then at 450°C, 1.5MPa, and the mass space velocity of the feed was 1h ^-1 , treated with C ₈ aromatic hydrocarbons (composed of 67.08% by mass of m-xylene, 24.31% by mass of o-xylene, and 8.60% by mass of ethylbenzene) for 2 hours. The C/Pt molar ratio on the catalyst surface after passivation was 1.3.

Example 10

(1) Ion exchange: Take 20 grams of the EUO molecular sieve D ₅ prepared in Example 5 and use 200 milliliters of 4 mass % ammonium chloride aqueous solution to perform ion exchange at 90° C. under continuous stirring for 2 hours, and exchange 2 times in total. After sufficient washing, the sodium content in the molecular sieve was 0.02% by mass, and the ion-exchanged molecular sieve was dried at 110° C. for 12 hours to obtain a hydrogen-type molecular sieve.

(2) Kneading molding: 5.6 grams of hydrogen-type molecular sieves, 59.2 grams of pseudo-boehmite, 5 grams of asparagus powder, and 30 milliliters of 4 volume % nitric acid aqueous solution are mixed uniformly, and strip-shaped particles are made after kneading, and roasted at 540 ° C for 6 hours to prepare the carrier.

(3) Loading metal elements: take 30 grams of carrier particles prepared in step (2), and add 50 milliliters of chloroplatinic acid solution with a concentration of 3.36 mg/ml at 25 ° C for 36 hours, dry at 110 ° C for 8 hours, 580 °C for 8 hours, the composition and platinum dispersion of the prepared catalyst _E5 are shown in Table 2.

(4) Reduction: The particles prepared in step (3) were reduced at 400° C. under normal pressure with H ₂ at a flow rate of 60 ml/min for 5 hours.

Comparative example 2

Prepare comparative catalyst E by the method for example 6, and difference is that the EUO type molecular sieve that adopts is the molecular sieve D prepared in comparative example 1, and the composition and the platinum dispersity of the catalyst E obtained after roasting are shown in Table 2, and catalyst surface S/ The Pt molar ratio is 1.5.

Examples 11-16

The following is an evaluation of the _C8 aromatics isomerization performance of the catalyst prepared by the method of the present invention.

20mm)中装填10克催化剂。将C₈芳烃经过缓冲罐用计量泵送入反应器与热的催化剂接触进行反应，产物进入高压分离罐，液相产物由其底部分出并用电子称计量。原料和产物分别用HP 4890-II气相色谱仪(TCD，Al₂O₃-PLOT色谱柱)分析。所述C₈芳烃组成为间二甲苯67.08质量％、邻二甲苯24.31质量％、乙苯8.60质量％，各实例所用催化剂及反应条件和结果见表3。The stainless steel reactor (80mm×

20mm) filled with 10 grams of catalyst. The C ₈ aromatics are sent into the reactor through the buffer tank with a metering pump to contact with the hot catalyst for reaction, and the product enters the high-pressure separation tank, and the liquid phase product is separated from the bottom of it and measured with an electronic scale. The raw materials and products were analyzed by HP 4890-II gas chromatograph (TCD, Al ₂ O ₃ -PLOT column). The C ₈ aromatics are composed of m-xylene 67.08% by mass, o-xylene 24.31% by mass, and ethylbenzene 8.60% by mass. The catalysts, reaction conditions and results used in each example are shown in Table 3.

The results in Table 3 show that the catalyst prepared by the method of the present invention is used in the isomerization reaction of _C8 aromatics compared with the comparison catalyst, the conversion rate of ethylbenzene is slightly higher, and the loss rate of aromatics is smaller, but the preparation cost of the molecular sieve used is greatly reduced.

Table 1

^* HxBr ₂ is 1,6-N,N,N,N′,N′,N′-hexamethylhexamethylenediamine, the simplified structure is [Me ₃ N(CH ₂ ) ₆ NMe ₃ ²⁺ (Br ^- ) ₂ ]

Table 2

table 3

Claims (20)

1. A preparation method of _C8 aromatic hydrocarbon isomerization catalyst, comprising making carrier after EUO type molecular sieve and binding agent are mixed and molded, then introducing VIII group metal in carrier, reducing with reducing gas after drying and roasting A catalyst is prepared, the catalyst contains 5-90% by mass of EUO type molecular sieve, 10-90% by mass of binder and 0.1-5.0% by mass of Group VIII metal, and the sum of the contents of each component is 100% , wherein the preparation method of the EUO type molecular sieve comprises mixing a compound containing element X, a compound of element T, or a compound containing both elements X and T with an alkali metal compound and water and stirring evenly, in crude dibromoalkane and monobasic The hydrothermal crystallization reaction is carried out in the presence of the template agent precursor prepared by the amine, and the solid is collected and dried. The X is selected from silicon or germanium, and T is selected from aluminum, iron, gallium or boron. The crude dibromoalkane It is a mixture of dibromoalkane, monobromoalcohol and alkanediol, wherein the content of dibromoalkane is 80-95% by mass, and the crude dibromoalkane is prepared by the following method: alkanediol and hydrogen bromide are mixed in acidic In the presence of a catalyst, fully react at reflux temperature, and then wash the oil phase with alkali solution. 2. The preparation method according to claim 1, characterized in that the crude dibromoalkane consists of 0.5-10% by mass of C ₄ -C ₈ alkanediol, 8-20% by mass of C ₄ -C ₈ It consists of monobromoalcohol and 80-90% by mass of _C4 - _C8 dibromoalkane, and the sum of the contents of each component is 100%. 3. according to the described preparation method of claim 1, it is characterized in that described thick dibromoalkane is by the hexylene glycol of 0.5～10 mass %, the monobromohexanol of 8～20 mass % and the 80～90 mass % Dibromohexane composition, the sum of the content of each component is 100%. 4. according to the described method of claim 1, it is characterized in that the mol ratio of described hydrogen bromide and alkanediol is 2～6: 1, and acid catalyst is the vitriol oil, and alkaline solution is sodium hydroxide solution. 5. The method according to claim 1, characterized in that said monoamine is a tertiary amine whose substituent is C ₁ -C ₃ alkyl. 6. according to the described method of claim 5, it is characterized in that described monoamine is trimethylamine. 7. according to the described method of claim 1, it is characterized in that the ratio of described monoamine and the total moles of each substance that crude dibromoalkane contains is 2.0～2.5:1. 8. according to the described method of claim 1, it is characterized in that in the preparation method of described EUO type molecular sieve, the mol ratio of each material in oxide compound in the reaction mixture is: XO ₂ /T ₂ O ₃ 5～150 OH ^- /XO ₂ 0.03～1.5 R/XO ₂ 0.02～0.7 M ₂ O/XO ₂ 0.015～0.8 H ₂ O/XO ₂ 1～300 Wherein, R is the total number of moles of each substance contained in the crude dibromoalkane, M is an alkali metal, and the reaction mixture is hydrothermally crystallized at 120-200° C. for 6-350 hours. 9. according to the described method of claim 8, it is characterized in that in the described reaction mixture, the mol ratio of each material in terms of oxide is: XO ₂ /T ₂ O ₃ 8～130 OH ^- /XO ₂ 0.05～1.3 R/XO ₂ 0.08～0.6 M ₂ O/XO ₂ 0.025～0.65 H ₂ O/XO ₂ 5～250 10. The method according to claim 1, wherein the silicon-containing compound is silicon dioxide, silica gel, water glass or silicate, and the aluminum-containing compound is sodium aluminate, aluminum sulfate, aluminum nitrate, alkoxy base aluminum compound, alumina, aluminum hydroxide colloid, pseudo-boehmite or boehmite. 11. The method according to claim 1, wherein the compound containing elements X and T is amorphous silicon aluminum, the boron-containing compound is boric acid, the gallium-containing compound is gallium oxide, and the alkali metal compound is sodium hydroxide. 12. according to the described method of claim 1, it is characterized in that described EUO type molecular sieve is EUO type silica-alumina molecular sieve, and described binding agent is selected from alumina, silica gel or silica-alumina gel, or alumina and A mixture of silica, silica gel or silica-alumina gel. 13. The method according to claim 12, characterized in that the content of silicon dioxide, silica gel or silica-alumina gel in the mixture is 5-75% by mass. 14. The method according to claim 1, characterized in that said EUO type molecular sieve is hydrogen type. 15. The method according to claim 1, wherein when the EUO-type molecular sieve is a sodium type, it is converted into a hydrogen-type molecular sieve by an ion exchange method and then molded, or the EUO-type molecular sieve is combined with a binder After mixing, it is formed first, and then the EUO type molecular sieve is converted into a hydrogen type by ion exchange. 16. The method according to claim 1, characterized in that the catalyst is prepared by impregnating the support with a compound solution containing the Group VIII metal to introduce the Group VIII metal. 17. according to the described method of claim 16, it is characterized in that containing group VIII metal compound is selected from platinum or palladium nitrate, halide, ammonium complex, acetate, halogen acid compound, halogen acid ammonium salt, carbonyl compounds or hydroxyl compounds. 18. The method according to claim 1, characterized in that the reduced catalyst is passivated by treating it with a reducing gas containing sulfide, carbide or ammonia at 250-600°C. 19. The preparation method according to claim 18, characterized in that said sulfide is hydrogen sulfide or thioalkane, and said carbide is sulfide carbide, C ₄ -C ₇ alkane, C ₄ -C ₇ Alkenes or C ₆ -C ₉ aromatics. 20. The method according to claim 18, characterized in that the molar ratio of sulfur, ammonia or carbon on the surface of the catalyst to surface metal elements after passivation treatment is 0.2-6.0.

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