Preparation method of cyclohexylbenzene

Abstract

The invention discloses a preparation method of cyclohexylbenzene. According to the method, benzene and cyclohexene are used as raw materials, a metal / MWW molecular sieve is used as a catalyst, alkylation reaction is carried out in a hydrogen atmosphere to prepare cyclohexylbenzene, and the molar ratio of hydrogen to benzene is 0.1-1.0. According to the method disclosed by the invention, relatively high cyclohexene conversion rate and benzene conversion rate can be obtained at relatively low reaction temperature, the yield of a target product is improved, and the problems of high reaction temperature, high selectivity of generated key impurity methylcyclopentylbenzene, short service life of a catalyst and the like in the prior art can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical production, and in particular to a method for preparing cyclohexylbenzene by alkylation of benzene and cyclohexene in the presence of hydrogen. Background Art

[0002] Cyclohexylbenzene (CHB) is a high value-added fine chemical. Its most important use is as an additive to lithium-ion secondary battery electrolytes. It can improve the battery's anti-overcharge performance, reduce the electrolyte's conductivity, and make the battery safer to use. Cyclohexylbenzene is also one of the raw materials for synthesizing liquid crystal thin film transistors (TFTs), which can improve the material's photochemical stability and reduce product viscosity. Cyclohexylbenzene also has a high cetane number and can be used as a diesel cetane number blending component. The most important potential use of cyclohexylbenzene is that it can be used to prepare phenol and cyclohexanone through oxidation and acid decomposition reactions, which can partially replace the existing process of preparing phenol by isopropylbenzene and alleviate the problem of excess production capacity of acetone. Cyclohexanone, a co-product of the cyclohexylbenzene-to-phenol route, has caprolactam as its downstream product, which is an important raw material for manufacturing synthetic fibers.

[0003] Cyclohexylbenzene can be prepared by Friedel-Crafts alkylation of benzene, hydrogenation of biphenyl or hydroalkylation of benzene. CN104105679A, CN110563534A, CN107930682A, CN105233862A and the like disclose some catalysts or methods for preparing cyclohexylbenzene by direct hydroalkylation of benzene; CN107185548A, CN107008477A, ​​CN1800121A and the like disclose some methods for preparing cyclohexylbenzene by selective hydrogenation of biphenyl. These methods have problems such as low yield of target product, difficulty in catalyst manufacturing and high cost.

[0004] Therefore, the Friedel-Crafts alkylation reaction of benzene is currently the most economical preparation method. CN1982263A discloses a method for preparing cyclohexylbenzene from benzene and cyclohexanol under the catalysis of liquid acids such as sulfuric acid and AlCl3, and the yield of cyclohexylbenzene reaches 90%. However, due to the use of inorganic liquid acid, there are prominent problems such as high energy consumption for product separation, large waste production, equipment corrosion, and intermittent reaction, which is only suitable for small-scale production.

[0005] CN101219922A, CN101811924A, CN109369322A, CN110606796A, etc. disclose a series of methods for preparing cyclohexylbenzene using acidic ionic liquids as catalysts, which can achieve the effect of inorganic liquid acid catalysis and have the advantage that the catalyst can be recycled multiple times. However, the preparation of ionic liquids requires anhydrous and oxygen-free conditions, and the preparation cost is high. Currently, the methods are still in the laboratory research and development stage.

[0006] The process of preparing cyclohexylbenzene by catalyzing the alkylation of benzene and cyclohexene under liquid-solid phase conditions using molecular sieve solid acid as a catalyst has the advantages of low product separation difficulty and continuous production, and has always been regarded as a potential alternative process for liquid acid catalysis. CN105367371A, CN106518600A, and CN108530247A respectively disclose methods for preparing cyclohexylbenzene by liquid-solid phase alkylation using MWW, BEA, MOR or FAU molecular sieves as catalysts. The reaction is carried out at a relatively high reaction temperature (170-220°C) for 72 hours, and the cyclohexene conversion rate is 82.8-99.8%, the cyclohexene selectivity is 60-87%, and the selectivity of the key impurity methylcyclopentylbenzene is relatively high, reaching 7.6-10.7%.

[0007] Since the molecular size of the alkylation product of benzene and cyclohexene is relatively large, it is very easy to cause clogging of the pores when using molecular sieves as catalysts, thereby deactivating them. Although increasing the reaction temperature can promote the diffusion of these molecules, it will also cause an increase in side reactions and improve the selectivity of key impurities such as methylcyclopentylbenzene. Among them, the boiling point of methylcyclopentylbenzene is close to that of cyclohexylbenzene, which makes it difficult to separate by distillation. Therefore, it is difficult to develop a catalytic reaction system that has both high selectivity and long catalyst life. Summary of the invention

[0008] In view of the outstanding problems in the prior art of the alkylation reaction of benzene with cyclohexene, such as low selectivity, high content of by-product methylcyclopentylhexylbenzene, and short catalyst life, the present invention provides a new method for preparing cyclohexylbenzene, which improves the yield of the target product cyclohexylbenzene, reduces the generation of the key impurity methylcyclopentylbenzene, and prolongs the service life, so that the alkylation reaction of benzene with cyclohexene can be carried out at a lower reaction temperature.

[0009] The invention provides a method for preparing cyclohexylbenzene. Benzene and cyclohexene are used as raw materials, metal / MWW molecular sieve is used as catalyst, and alkylation reaction is carried out in a hydrogen atmosphere to prepare cyclohexylbenzene, wherein the molar ratio of hydrogen to benzene is 0.1-1.0, preferably 0.2-0.6.

[0010] Furthermore, the method adopts a fixed bed reactor.

[0011] Furthermore, the temperature of the alkylation reaction is 80 to 200°C, preferably 110 to 150°C.

[0012] Furthermore, the total mass space velocity of the raw materials benzene and cyclohexene is 0.1 to 6.0 h -1 , preferably 1.0~4.0h -1 .

[0013] Furthermore, the pressure of the alkylation reaction is 1.0 to 4.0 MPa, preferably 1.5 to 2.5 MPa.

[0014] Furthermore, the catalyst is pre-reduced before the alkylation reaction, the reducing gas is hydrogen, the pre-reduction temperature is 100-400° C., preferably 150-300° C., and the pre-reduction time is 0.1-10 h, preferably 1-5 h.

[0015] Furthermore, in the preparation method of cyclohexylbenzene, the molar ratio of raw material benzene to cyclohexene is 3 to 30, preferably 5 to 15; the water content in the raw material benzene and cyclohexene is <100 mg / kg, preferably <50 mg / kg, the total nitrogen content is <0.1 mg / kg, preferably <0.05 mg / kg, and the total sulfur content is <0.1 mg / kg, preferably <0.05 mg / kg.

[0016] Furthermore, in the method for preparing cyclohexylbenzene, the raw materials benzene and cyclohexene can be selectively pre-treated with dehydration and de-alkalization according to the impurity content. The pre-treatment can be carried out by adsorption, for example, using 13X molecular sieve as an adsorbent.

[0017] Furthermore, the SiO2 / Al2O3 molar ratio of the MWW molecular sieve is 10-100, preferably 20-40.

[0018] Furthermore, the layer thickness of the MWW molecular sieve is 5 to 10 nm.

[0019] Furthermore, the metal is copper and / or silver.

[0020] Furthermore, in the catalyst, based on the weight of the catalyst, the content of metal as an element is 0.01% to 1.00%, preferably 0.05% to 0.30%, and the content of MWW molecular sieve is 80% to 95%.

[0021] Furthermore, the catalyst also includes a binder, which is at least one of aluminum oxide or silicon oxide. The content of the binder in terms of oxide is 5% to 20%, preferably 7% to 15%, based on the weight of the catalyst.

[0022] Furthermore, the preparation method of the catalyst comprises the following steps:

[0023] (1) mixing a silicon source, an aluminum source, an alkali source, water, a first template (T1) and a second template (T2), and crystallizing them to obtain an intermediate;

[0024] (2) The intermediate obtained in step (1) is subjected to acid exchange, metal impregnation, molding, and calcination to obtain the catalyst.

[0025] Furthermore, in step (1), the alkali source, water, the first template (T1) and the second template (T2) are first mixed, then the silicon source is added and stirred, and finally the aluminum source is added, and then aged at 0-40° C. for 1-12 hours and then crystallized.

[0026] Furthermore, in step (1), the silicon source is selected from at least one of silicon dioxide, silica sol, white carbon, water glass, sodium silicate or tetraethyl silicate, preferably silicon dioxide.

[0027] Furthermore, in step (1), the aluminum source is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, aluminum isopropoxide, aluminum sol or aluminum hydroxide, and is preferably aluminum nitrate.

[0028] Furthermore, in step (1), the alkali source is selected from at least one of sodium hydroxide and potassium hydroxide, preferably sodium hydroxide.

[0029] Furthermore, in step (1), the first template (T1) is selected from at least one of hexamethyleneimine, tetrahydropyrrole, hexahydropyridine, 2-methylhexahydropyridine or heptamethyleneimine, preferably at least one of hexamethyleneimine and hexahydropyridine; the second template (T2) is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, didecyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride and octadecyltrimethylammonium bromide, preferably at least one of hexadecyltrimethylammonium bromide and dodecyltrimethylammonium chloride.

[0030] Furthermore, in step (1), the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the alkali is calculated as OH - The molar ratio of each material is: SiO2 / Al2O3 is 10-100, preferably 20-40; OH - / SiO2 is 0-0.40, preferably 0.05-0.15; H2O / SiO2 is 10-50, preferably 20-30; T1 / SiO2 is 0.05-1.0, preferably 0.1-0.5; T2 / SiO2 is 0.001-0.1, preferably 0.01-0.04.

[0031] Furthermore, in step (1), the crystallization adopts dynamic crystallization, the stirring rate is 10-200 rpm, preferably 20-100 rpm; the crystallization temperature is 100-200° C., preferably 150-180° C.; the crystallization time is 24-144 h, preferably 48-96 h.

[0032] Furthermore, in step (1), after the crystallization is completed, the product is washed and dried for later use, wherein the washing and drying are conventional operations in the art.

[0033] Furthermore, in step (1), the SiO2 / Al2O3 molar ratio of the intermediate, i.e. the ultra-thin layered MWW molecular sieve, is 10 to 100, preferably 20 to 40.

[0034] Furthermore, in step (2), the acid exchange conditions include: temperature of 20-100°C, preferably 65-95°C; time of 0.5-24h / time, preferably 3-8h / time; acid concentration of 0.001-2mol / L, preferably 0.01-0.5mol / L; acid exchange times of 1-6 times, preferably 2-5 times. The mass ratio of acid solution to molecular sieve is 2-20, preferably 5-10.

[0035] Furthermore, in step (2), the acid is an organic acid and / or an inorganic acid; preferably, the acid is at least one of oxalic acid, citric acid, formic acid, acetic acid, propionic acid, sulfuric acid, nitric acid and hydrochloric acid.

[0036] Furthermore, in step (2), after the acid exchange is completed, the product is washed and dried for later use, wherein washing and drying are conventional operations in the art.

[0037] Furthermore, in step (2), the metal precursor used in the impregnation process is a soluble silver salt and / or copper salt. The silver salt is preferably silver nitrate, and the copper salt is preferably at least one of copper nitrate or copper sulfate. The mass concentration of the metal salt solution is 0.01% to 1.60%, preferably 0.04% to 0.46%.

[0038] Furthermore, in step (2), the impregnation process includes: dissolving the metal salt in deionized water according to the required concentration, impregnating the metal salt with the MWW molecular sieve sample in equal volumes, and drying. The impregnation time is 1 to 12 hours, preferably 2 to 8 hours; the drying temperature is 50 to 150° C., preferably 80 to 120° C., and the drying time is 2 to 48 hours, preferably 6 to 24 hours.

[0039] Furthermore, in step (2), the binder used in the molding process is at least one of pseudo-boehmite, silica sol, γ-alumina, aluminum hydroxide, and white carbon black, preferably pseudo-boehmite or silica sol. The weight content of the binder in the catalyst is 5% to 20%, preferably 7% to 15%, calculated as oxide.

[0040] Furthermore, in step (2), the calcination temperature is 350-650° C., preferably 500-600° C., and the calcination time is 1-10 h, preferably 2-8 h.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The catalyst of the present invention has better alkylation activity and selectivity. Benzene and cyclohexene can be reacted at a lower temperature. Cyclohexene does not need to be fed in stages to achieve good selectivity. The selectivity of the key by-product methylcyclopentylbenzene is greatly reduced, which can greatly reduce separation energy consumption and improve the purity of the product cyclohexylbenzene.

[0043] (2) The present invention, through the introduction of hydrogen and the modification of the catalyst, can, on the one hand, allow part of the benzene to undergo a hydroalkylation reaction and be converted into the target product cyclohexylbenzene, thereby improving its yield; on the other hand, it can slow down the rate of catalyst deactivation due to carbon deposition. Under the reaction process conditions used in the present invention, the catalyst has a long service life and can meet the requirements of industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 XRD pattern of catalyst S2 synthesized in Example 2;

[0045] Figure 2 TEM photo of the molecular sieve intermediate synthesized in Example 2;

[0046] Figure 3 TEM image of catalyst S2 synthesized in Example 2. DETAILED DESCRIPTION

[0047] The present invention will be further described below by way of examples.

[0048] In the present invention, the XRD spectrum of the catalyst is characterized by a Bruker D8 Advanced X-ray diffractometer for phase analysis of the catalyst sample, with a scanning range of 3 to 50°, a step length of 0.05°, and a scanning speed of 4° / min.

[0049] In the present invention, the TEM photograph of the catalyst was taken using a JEOL-2010F electron microscope, and the TEM photograph was observed using a FEINova NanoSEM 450 electron microscope.

[0050] In the present invention, the product after the alkylation reaction of benzene and cyclohexene is analyzed by gas chromatography (GC-FID), and key indicators such as cyclohexene conversion rate, cyclohexylbenzene selectivity, cyclohexylation selectivity, and methylcyclopentylhexylbenzene selectivity are calculated according to the following formulas:

[0051] Cyclohexene conversion rate = (cyclohexene mass percentage before reaction - cyclohexene mass percentage after reaction) / (cyclohexene mass percentage before reaction) × 100%;

[0052] Benzene conversion rate = (benzene mass percentage before reaction - benzene mass percentage after reaction) / (benzene mass percentage before reaction) × 100%;

[0053] Cyclohexylbenzene selectivity = (cyclohexylbenzene mass percentage) / (total mass percentage of all products and by-products) × 100%;

[0054] Cyclohexylation selectivity = (mass percentage of cyclohexylbenzene + dicyclohexylbenzene) / (total mass percentage of all products and by-products) × 100%;

[0055] Methylcyclopentylbenzene selectivity=(mass percentage of methylcyclopentylbenzene) / (total mass percentage of all products and by-products)×100%.

[0056] [Example 1]

[0057] (1) Add 3.6g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g hexadecyltrimethylammonium bromide (CTAB) to 139.1g water, and after fully dissolving and mixing, add 18.0g silica powder, stir vigorously, and then add 7.5g aluminum nitrate nonahydrate. Age at room temperature (25°C) for 6h, and transfer to a high-pressure bomb equipped with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 165°C, the crystallization time is 96h, and the rotation speed is 40rpm. After the crystallization is completed, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0058] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio was measured to be 29.5, thickness was 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution, the exchange temperature was 80°C, the time was 5 h / time, and the exchange was repeated 4 times. After washing and drying, silver nitrate solution was added, the weight percentage concentration was 0.05%, and the mixture was immersed in equal volume for 6 h, and dried at 95°C for 12 h. Then pseudo-boehmite and dilute nitric acid (accounting for 2.5% of the total weight of the catalyst) were added to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5 h, and then an alkylation catalyst was prepared, which was numbered S1. The silver content in the catalyst was 0.06%.

[0059] [Example 2]

[0060] The molecular sieve intermediate prepared in step (1) of Example 1 was subjected to acid exchange, washing and drying under the same conditions as in Example 1, and then a silver nitrate solution was added with a weight percentage concentration of 0.10%, and the mixture was impregnated for 6 h at equal volume and dried at 95° C. for 12 h. The molding process conditions were the same as in Example 1 to prepare an alkylation catalyst, numbered S2, in which the silver content of the catalyst was 0.12%.

[0061] [Example 3]

[0062] The molecular sieve intermediate prepared in step (1) of Example 1 was subjected to acid exchange, washing and drying under the same conditions as in Example 1, and then a silver nitrate solution was added with a weight percentage concentration of 0.20%, and the mixture was impregnated for 6 h at an equal volume and dried at 95° C. for 12 h. The molding process conditions were the same as in Example 1, and the alkylation catalyst prepared was numbered S3, and the silver content in the catalyst was 0.24%.

[0063] [Example 4]

[0064] The molecular sieve intermediate prepared in step (1) of Example 1 was exchanged in a 0.1 mol / L hydrochloric acid solution at an exchange temperature of 80°C for 5 hours per time and exchanged 4 times. After washing and drying, a copper nitrate solution was added with a weight percentage concentration of 0.19%, and the mixture was immersed in equal volume for 6 hours and dried at 95°C for 12 hours. Pseudo-boehmite and dilute nitric acid were then added for molding to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3 to 10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The mixture was calcined in air at 525°C for 5 hours to prepare an alkylation catalyst, which was numbered S4. The copper content in the catalyst was 0.12%.

[0065] [Example 5

[0066] The molecular sieve intermediate prepared in step (1) of Example 1 was subjected to acid exchange, washing and drying under the same conditions as in Example 4, and then a copper nitrate solution was added with a weight percentage concentration of 0.37%, and the mixture was immersed in equal volume for 6 hours and dried at 95° C. for 12 hours. The molding process conditions were the same as in Example 4, and the alkylation catalyst prepared was numbered S5, and the copper content in the catalyst was 0.24%.

[0067] [Example 6]

[0068] Compared with Example 2, the only difference is that the acid exchange conditions are changed as follows: the intermediate product is exchanged in a 0.25 mol / L sulfuric acid solution, the exchange temperature is 75°C, the time is 4 hours / time, and the exchange is performed 5 times. After washing and drying, a silver nitrate solution is added with a weight percentage concentration of 0.10%, and the equal volume is immersed for 6 hours, and dried at 105°C for 12 hours.

[0069] The alkylation catalyst prepared in Example 6 is numbered S6, and the silver content in the catalyst is 0.12%.

[0070] [Example 7]

[0071] Compared with Example 2, the only difference is that the amount of pseudo-boehmite added as a binder in the molding is changed to 14.8% and the amount of dilute acid added is changed to 3.5%.

[0072] The alkylation catalyst prepared in Example 7 is numbered S7, and the silver content in the catalyst is 0.12%.

[0073] [Example 8]

[0074] (1) Add 4.1g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g hexadecyltrimethylammonium bromide (CTAB) to 139.8g water, fully dissolve and mix, then add 18.0g silica powder, stir vigorously, add 9.0g aluminum nitrate nonahydrate, age at room temperature for 6h, and transfer to a high-pressure bomb equipped with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 155°C, the crystallization time is 84h, and the rotation speed is 40rpm. After the crystallization is completed, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 25Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0075] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio was determined to be 24.3, thickness was 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution, the exchange temperature was 80°C, the time was 5 h / time, and the exchange was repeated 4 times. After washing and drying, silver nitrate solution was added, the weight percentage concentration was 0.10%, and the mixture was immersed in equal volume for 6 h, and dried at 95°C for 12 h. Then pseudo-boehmite and dilute nitric acid (2.5%) were added to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5 h, and then an alkylation catalyst was prepared, which was numbered S8. The silver content in the catalyst was 0.12%.

[0076] [Example 9]

[0077] (1) Add 2.5g NaOH, 13.4g hexamethyleneimine (HMI), and 2.18g hexadecyltrimethylammonium bromide (CTAB) to 121.8g water, and after fully dissolving and mixing, add 18.0g silica powder, stir vigorously, and then add 5.6g aluminum nitrate nonahydrate. Age at room temperature for 6h, and transfer to a high-pressure bomb equipped with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 165°C, the crystallization time is 96h, and the rotation speed is 40rpm. After the crystallization is completed, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 40Al2O3:0.06OH - :22H2O:0.45HMI:0.020CTAB.

[0078] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio was measured to be 38.9, thickness was 5.0-7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution, the exchange temperature was 80°C, the time was 5 h / time, and the exchange was repeated 4 times. After washing and drying, silver nitrate solution was added, the weight percentage concentration was 0.10%, and the mixture was immersed in equal volume for 6 h, and dried at 95°C for 12 h. Then pseudo-boehmite and dilute nitric acid (2.5%) were added to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5 h, and then an alkylation catalyst was prepared, which was numbered S9. The silver content in the catalyst was 0.12%.

[0079] [Example 10]

[0080] (1) Add 3.6g NaOH, 10.2g hexahydropyridine (PI, piperidine), and 1.4g hexadecyltrimethylammonium chloride (CTAC) to 139.1g water, and after fully dissolving and mixing, add 18.0g silica powder, stir vigorously, and then add 7.5g aluminum nitrate nonahydrate. Age at room temperature for 6h, and transfer to a high-pressure bomb equipped with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 165°C, the crystallization time is 96h, and the rotation speed is 40rpm. After the crystallization is completed, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40PI:0.015CTAC.

[0081] (2) The intermediate product obtained above (SiO2 / Al2O3 molar ratio was measured to be 24.7, thickness was 5.0-10.0 nm) was exchanged in 0.1 mol / L hydrochloric acid solution, the exchange temperature was 80°C, the time was 5 h / time, and the exchange was repeated 4 times. After washing and drying, silver nitrate solution was added, the weight percentage concentration was 0.10%, and the mixture was immersed in equal volume for 6 h, and dried at 95°C for 12 h. Then pseudo-boehmite and dilute nitric acid (2.5%) were added to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3-10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5 h, and then an alkylation catalyst was prepared, which was numbered S10. The silver content in the catalyst was 0.12%.

[0082] [Example 11]

[0083] Compared with Example 2, the only difference is that 0.2 mol / L citric acid is used instead of 0.1 mol / L hydrochloric acid.

[0084] The alkylation catalyst prepared in Example 11 is numbered S11, and the silver content in the catalyst is 0.12%.

[0085] [Comparative Example 1]

[0086] (1) Add 3.6g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g hexadecyltrimethylammonium bromide (CTAB) to 139.1g water, and after fully dissolving and mixing, add 18.0g silica powder, stir vigorously, and then add 7.5g aluminum nitrate nonahydrate. Age at room temperature for 6h, and transfer to a high-pressure bomb equipped with a polytetrafluoroethylene liner for crystallization. The crystallization temperature is 165°C, the crystallization time is 96h, and the rotation speed is 40rpm. After the crystallization is completed, wash with pure water, dry, and set aside. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

[0087] (2) The molecular sieve intermediate product was exchanged in a 0.1 mol / L hydrochloric acid solution at a temperature of 80°C for 5 hours per exchange, and exchanged 4 times. After washing and drying, pseudo-boehmite and dilute nitric acid were added to form a catalyst cylindrical strip with a diameter of 1.5 mm and a length of 3 to 10 mm. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 10% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5 hours to prepare an alkylation catalyst, which was numbered C1.

[0088] [Comparative Example 2]

[0089] The invention cites CN 104513122A (CN201310450053.9) for preparing cyclohexylbenzene by liquid phase alkylation of benzene and cyclohexene.

[0090] Commercially available H-MCM-22 molecular sieve (SiO2 / Al2O3=29.6), pseudo-boehmite and dilute nitric acid are mixed and molded into catalyst cylindrical bars with a diameter of 1.5 mm and a length of 3 to 10 mm. The amount of pseudo-boehmite added is calculated on a dry basis and accounts for 30% of the total weight of the catalyst. The mixture is calcined in air at 525°C for 5 hours to prepare an alkylation catalyst C2.

[0091] (Comparative Example 3)

[0092] The invention cites CN 104510123A (CN201310451337.X) for preparing cyclohexylbenzene by liquid phase alkylation of benzene and cyclohexene.

[0093] Commercially available USY molecular sieve (SiO2 / Al2O3=6.1), pseudo-boehmite and dilute nitric acid were mixed and molded into catalyst cylindrical bars of Φ1.5mm and 3-10mm in length. The amount of pseudo-boehmite added was calculated on a dry basis and accounted for 25% of the total weight of the catalyst. The catalyst was calcined in air at 525°C for 5h to prepare the alkylation catalyst C3.

[0094] [Comparative Example 4]

[0095] Compared with Example 1, the only difference is that an equal mole of dipentyldimethylammonium iodide (DPenDMAI) is used to replace hexadecyltrimethylammonium bromide (CTAB).

[0096] Comparative Example 4: Alkylation catalyst C4 was prepared. The silver content in the catalyst was 0.12%.

[0097]

Application Example 1

[0098] In the presence of hydrogen, benzene and cyclohexene are subjected to an alkylation reaction under the catalysis of the above-prepared catalyst to prepare cyclohexylbenzene. The raw materials benzene and cyclohexene are dehydrated with 13X molecular sieves and pretreated with de-alkalization substances, and then fully mixed. The molar ratio of benzene to cyclohexene is 10; the water content in the raw materials is 15 mg / kg, the total nitrogen content is 0.03 mg / kg, and the total sulfur content is 0.05 mg / kg. The catalysts prepared in Examples 1 to 11 and Comparative Examples 1 to 4 are respectively loaded in a fixed bed reactor with a loading amount of 3.0 g. Pre-reduction is first carried out under normal pressure hydrogen conditions, with a reduction temperature of 250°C and a time of 4 hours. The temperature is lowered to 130°C, the pressure is increased to 2.0 MPa, and the raw materials configured and pretreated as above are introduced at a hydrogen / benzene molar ratio of 0.5, with a flow rate of 6.0 g / h, that is, the raw material space velocity is 2.0 h -1 The reaction products were analyzed and calculated by gas chromatography, and the results are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] * Data with a response time of 72 hours,

[0103] **Reaction time for cyclohexene conversion > 99.8%.

[0104]

Application Example 2

[0105] In the presence of hydrogen, benzene and cyclohexene are subjected to an alkylation reaction under the catalysis of the above-prepared catalyst to prepare cyclohexylbenzene. The raw materials benzene and cyclohexene are dehydrated with 13X molecular sieves and pretreated with de-alkalizing substances, and then fully mixed. The molar ratio of benzene to cyclohexene is 12.5; the water content in the raw material is 56 mg / kg, the total nitrogen content is 0.05 mg / kg, and the total sulfur content is 0.07 mg / kg. The catalysts prepared in Example 2 and Comparative Examples 1 and 4 are respectively loaded into a fixed bed reactor, and first pre-reduced under normal pressure hydrogen conditions, with a reduction temperature of 200°C and a time of 3 hours. The temperature is lowered to 140°C, the pressure is increased to 2.5MPa, and the raw material configured and pretreated as above is introduced at a hydrogen / benzene molar ratio of 0.4, with a flow rate of 12.0 g / h, that is, the raw material space velocity is 4.0 h -1 The reaction products were analyzed and calculated by gas chromatography, and the results are shown in Table 2.

[0106] Table 2

[0107]

[0108] * Data with a response time of 72 hours,

[0109] **Reaction time for cyclohexene conversion > 99.8%.

[0110]

Application Example 3

[0111] In the presence of hydrogen, benzene and cyclohexene are subjected to an alkylation reaction under the catalysis of the above-prepared catalyst to prepare cyclohexylbenzene. The raw materials benzene and cyclohexene are dehydrated with 13X molecular sieves and pretreated with de-alkalizing substances, and then fully mixed. The molar ratio of benzene to cyclohexene is 20; the water content in the raw material is 15 mg / kg, the total nitrogen content is 0.03 mg / kg, and the total sulfur content is 0.05 mg / kg. The catalysts prepared in Example 2 and Comparative Examples 1 and 4 are respectively loaded in a fixed bed reactor with a loading amount of 3.0 g. Pre-reduction is first carried out under normal pressure hydrogen conditions, with a reduction temperature of 400°C and a time of 2 hours. The temperature is lowered to 180°C, the pressure is increased to 3.0 MPa, and the raw materials configured and pretreated as above are introduced at a hydrogen / benzene molar ratio of 0.8, with a flow rate of 6.0 g / h, that is, the raw material space velocity is 2.0 h -1 The reaction products were analyzed and calculated by gas chromatography, and the results are shown in Table 3.

[0112] Table 3

[0113]

[0114] * Data with a response time of 72 hours,

[0115] **Reaction time for cyclohexene conversion > 99.8%.

[0116]

Comparative Application Example 1

[0117] In the absence of hydrogen, benzene and cyclohexene are subjected to an alkylation reaction under the catalysis of the above-prepared catalyst to prepare cyclohexylbenzene. The raw materials benzene and cyclohexene are dehydrated with 13X molecular sieves and pretreated with de-alkalizing substances, and then fully mixed. The molar ratio of benzene to cyclohexene is 10; the water content in the raw materials is 15 mg / kg, the total nitrogen content is 0.03 mg / kg, and the total sulfur content is 0.05 mg / kg. The catalysts prepared in Example 2 and Comparative Examples 1 and 4 are respectively loaded into a fixed bed reactor with a loading amount of 3.0 g. The temperature is adjusted to 130°C, the pressure is increased to 2.0 MPa, and the raw materials configured and pretreated as above are introduced at a flow rate of 6.0 g / h, that is, the raw material space velocity is 2.0 h -1 The reaction products were analyzed and calculated by gas chromatography, and the results are shown in Table 4.

[0118] Table 4

[0119]

[0120] * Data with a response time of 72 hours,

[0121] **Reaction time for cyclohexene conversion > 99.8%.

[0122] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing cyclohexylbenzene, using benzene and cyclohexene as raw materials, using metal / MWW molecular sieve as catalyst, and carrying out alkylation reaction in a hydrogen atmosphere to obtain cyclohexylbenzene, wherein: The molar ratio of hydrogen to benzene is 0.1 to 1.0, preferably 0.2 to 0.

6.

2. The preparation method according to claim 1, characterized in that: The method uses a fixed bed reactor.

3. The preparation method according to claim 1 or 2, characterized in that: The temperature of the alkylation reaction is 80-200°C, preferably 110-150°C; and / or the total mass space velocity of benzene and cyclohexene is 0.1-6.0h -1 , preferably 1.0~4.0h -1 ; and / or, the pressure of the alkylation reaction is 1.0 to 4.0 MPa, preferably 1.5 to 2.5 MPa.

4. The preparation method according to claim 1 or 2, characterized in that: The catalyst is pre-reduced before the alkylation reaction, the reducing gas is hydrogen, the pre-reduction temperature is 100-400° C., preferably 150-300° C., and the pre-reduction time is 0.1-10 h, preferably 1-5 h.

5. The preparation method according to claim 1, characterized in that: The molar ratio of benzene to cyclohexene is 3 to 30, preferably 5 to 15; and / or the water content in the raw benzene and cyclohexene is <100 mg / kg, preferably <50 mg / kg, the total nitrogen content is <0.1 mg / kg, preferably <0.05 mg / kg, and the total sulfur content is <0.1 mg / kg, preferably <0.05 mg / kg.

6. The preparation method according to claim 1 or 5, characterized in that: The benzene and cyclohexene raw materials are dehydrated and de-alkalized before the reaction.

7. The preparation method according to claim 1, characterized in that: The SiO2 / Al2O3 molar ratio of the MWW molecular sieve is 10 to 100, preferably 20 to 40; and / or the layer thickness of the MWW molecular sieve is 5 to 10 nm.

8. The preparation method according to claim 1, characterized in that: The metal is copper and / or silver.

9. The preparation method according to claim 1 or 8, characterized in that: In the catalyst, based on the weight of the catalyst, the content of metal in terms of element is 0.01% to 1.00%, preferably 0.05% to 0.30%, and the content of MWW molecular sieve is 80% to 95%.

10. The preparation method according to claim 1, characterized in that: The catalyst comprises a binder, and the content of the binder in terms of oxide is 5% to 20%, preferably 7% to 15%, based on the weight of the catalyst; the binder is at least one of aluminum oxide or silicon oxide.

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