A process for the preparation of cyclohexylbenzene

Abstract

The application discloses a preparation method of cyclohexylbenzene. The method is to use benzene and cyclohexene as raw materials, use metal / MWW molecular sieve as a catalyst, and generate alkylization reaction under hydrogen atmosphere to obtain cyclohexylbenzene, wherein the molar ratio of hydrogen to benzene is 0.1-1.0. The method can obtain higher conversion rate of cyclohexene and benzene at a lower reaction temperature, improve the yield of the target product, and solve the problems of high reaction temperature, high selectivity of the key impurity methylcyclopentylbenzene, short service life of the catalyst and the like in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemicals, and particularly relates to a method for preparing cyclohexylbenzene by alkylation of benzene and cyclohexene in the presence of hydrogen. BACKGROUND

[0002] Cyclohexylbenzene (CHB) is a high value-added fine chemical. At present, the most important use is as an additive for lithium ion secondary battery electrolyte, which can improve the overcharge resistance of the battery, reduce the conductivity of the electrolyte, and make the battery use safer. Cyclohexylbenzene is also one of the raw materials for synthesizing liquid crystal material thin film transistors (TFT), which can improve the photochemical stability of the material and reduce the viscosity of the product. Cyclohexylbenzene also has a high cetane number and can be used as a cetane blending component for diesel. The most important potential use of cyclohexylbenzene is that it can be used to prepare phenol and cyclohexanone through oxidation and acid decomposition reaction, which can partially replace the existing cumene process for preparing phenol and alleviate the overcapacity problem of co-produced acetone. As a co-product of the cyclohexylbenzene route for preparing phenol, cyclohexanone is an important raw material for the manufacture of synthetic fibers.

[0003] Cyclohexylbenzene can be prepared by the Friedel-Crafts alkylation of benzene, the hydrogenation of biphenyl, or the 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, high difficulty in manufacturing catalyst, and high cost.

[0004] Therefore, the Friedel-Crafts alkylation of benzene is the most economical preparation method at present. CN1982263A discloses a method for preparing cyclohexylbenzene by the reaction of benzene and cyclohexanol in the presence of liquid acid such as sulfuric acid and AlCl3. The yield of cyclohexylbenzene reaches 90%, but due to the use of inorganic liquid acid, there are prominent problems such as high energy consumption for product separation, high waste production, equipment corrosion, and batch reaction, which are only suitable for small batch production.

[0005] CN101219922A, CN101811924A, CN109369322A, CN110606796A and the like disclose a series of methods for preparing cyclohexylbenzene using acidic ionic liquid as catalyst, which can achieve the effect of inorganic liquid acid catalysis and has the advantage of recyclable catalyst, but the preparation of ionic liquid requires anhydrous and oxygen-free conditions, which has a high preparation cost and is still at the stage of laboratory research and development.

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

[0007] Since the product molecules of benzene and cyclohexene alkylation are relatively large in size, when molecular sieve is used as catalyst, the pores are easily blocked, resulting in deactivation. Although increasing the reaction temperature can promote the diffusion of these molecules, it will also cause an increase in side reactions and an increase in the selectivity of key impurities such as methylcyclopentylbenzene. Among them, the boiling point of methylcyclopentylbenzene is close to that of cyclohexylbenzene, and there is difficulty in rectification separation. Therefore, it is difficult to develop a catalytic reaction system with high selectivity and long catalyst life. SUMMARY

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

[0009] The present application provides a method for preparing cyclohexylbenzene, which uses benzene and cyclohexene as raw materials and metal / MWW molecular sieve as catalyst to carry out alkylation reaction under hydrogen atmosphere to obtain cyclohexylbenzene, wherein the molar ratio of hydrogen to benzene is 0.1-1.0, preferably 0.2-0.6.

[0010] Further, the method uses a fixed bed reactor.

[0011] Further, the temperature of the alkylation reaction is 80-200℃, preferably 110-150℃.

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

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

[0014] Further, 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 0.1-10h, preferably 1-5h.

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

[0016] Further, in the preparation method of the cyclohexylbenzene, the raw benzene and cyclohexene can be selectively pretreated by dehydration and dealkaline according to the impurity content. The pretreatment can be carried out by adsorption, such as using 13X molecular sieve as the adsorbent.

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

[0018] Further, the lamellar thickness of the MWW molecular sieve is 5-10nm.

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

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

[0021] Further, the catalyst further comprises a binder, which is at least one of alumina and silica. The content of the binder in terms of oxide is 5%-20%, preferably 7%-15%, based on the weight of the catalyst.

[0022] Further, 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 agent (T1) and a second template agent (T2), crystallizing to obtain an intermediate;

[0024] (2) acid exchanging the intermediate obtained in step (1), impregnating a metal, shaping, and calcining to obtain the catalyst.

[0025] Further, in step (1), the base source, water, the first template agent (T1) and the second template agent (T2) are mixed first, then the silicon source is added and stirred, and finally the aluminum source is added, and the mixture is aged at 0-40℃ for 1-12h before crystallization.

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

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

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

[0029] Further, in step (1), the first template agent (T1) is selected from at least one of hexamethylene imine, tetrahydropyrrole, hexahydropyridine, 2-methylhexahydropyridine or heptamethylene imine, and preferably is at least one of hexamethylene imine and hexahydropyridine; and the second template agent (T2) is selected from at least one of cetyltrimethylammonium bromide, dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, didecyldimethylammonium chloride, tetradecyldimethylbenzylammonium chloride and octadecyltrimethylammonium bromide, and preferably is at least one of cetyltrimethylammonium bromide and dodecyltrimethylammonium chloride.

[0030] Further, in step (1), the silicon source is calculated as SiO2, the aluminum source is calculated as Al2O3, and the base is calculated as OH - , and 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; and T2 / SiO2 is 0.001-0.1, preferably 0.01-0.04.

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

[0032] Further, in step (1), after the crystallization is completed, the product is washed and dried before use. The washing and drying are both conventional operations in the art.

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

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

[0035] Further, 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] Further, in step (2), after the acid exchange, the product is washed and dried for standby. The washing and drying are both conventional operations in the art.

[0037] Further, in step (2), the metal precursor used in the impregnation process is a soluble silver salt and / or a 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%-1.60%, preferably 0.04%-0.46%.

[0038] Further, in step (2), the impregnation process includes: dissolving the metal salt in deionized water according to the required concentration, and carrying out equal-volume impregnation with the MWW molecular sieve sample, and drying. The impregnation time is 1-12h, preferably 2-8h; the drying temperature is 50-150℃, preferably 80-120℃, and the drying time is 2-48h, preferably 6-24h.

[0039] Further, in step (2), the binder used in the shaping 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, calculated as the oxide, is 5%-20%, preferably 7%-15%.

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

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

[0042] (1) The catalyst has better alkylation activity and selectivity, benzene and cyclohexene can be reacted at a lower reaction temperature, cyclohexene does not need to be fed in stages, and good selectivity can be achieved, the selectivity of the key by-product methylcyclopentyl benzene is greatly reduced, the separation energy consumption can be greatly reduced, and the purity of the product cyclohexyl benzene is improved.

[0043] (2) By introducing hydrogen and modifying the catalyst, on the one hand, part of the benzene can be subjected to a hydrogenation alkylation reaction to convert into the target product cyclohexyl benzene, and the yield thereof is improved; on the other hand, the carbon deposition deactivation rate of the catalyst can be delayed. Under the reaction process conditions used in the application, the catalyst has a longer service life and can meet the requirements of industrial applications. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

[0047] The application will be further described through examples.

[0048] In the application, the XRD pattern of the catalyst is analyzed and characterized by using a Bruker D8 Advanced X-ray diffractometer, the scanning range is 3-50°, the step is 0.05°, and the scanning speed is 4° / min.

[0049] In the application, the TEM photo of the catalyst is taken by using a JEOL-2010F electron microscope, and the TEM photo is observed by using a FEINova NanoSEM 450 electron microscope.

[0050] In the application, the product after the alkylation reaction of benzene and cyclohexene is analyzed by using a gas chromatograph (GC-FID), and the cyclohexene conversion rate, cyclohexyl benzene selectivity, cyclohexylation selectivity, methylcyclopentyl benzene selectivity and other key indicators are calculated according to the following formula:

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

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

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

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

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

[0056] Example 1

[0057] (1) To 139.1 g of water, 3.6 g of NaOH, 11.9 g of hexamethyleneimine (HMI), and 1.6 g of cetyltrimethylammonium bromide (CTAB) were added, dissolved, and mixed, and then 18.0 g of silica powder was added. After stirring vigorously, 7.5 g of aluminum nitrate nonahydrate was added, and the mixture was aged at room temperature (25°C) for 6 h. The mixture was then transferred to a high-pressure container equipped with a polytetrafluoroethylene liner and subjected to crystallization at a temperature of 165°C for 96 h at a rotation speed of 40 rpm. After the crystallization was completed, the product was washed with pure water and dried, and was then used as a catalyst. The synthesis ratio of the above-mentioned molecular sieve was: 1 SiO2: 1 / 30 Al2O3: 0.10 OH - : 25 H2O: 0.40 HMI: 0.015 CTAB.

[0058] (2) The above-mentioned intermediate product (molar ratio of SiO2 / Al2O3: 29.5, thickness: 5.0-7.5 nm) was exchanged in a 0.1 mol / L hydrochloric acid solution at a temperature of 80°C for 5 h per exchange, and was exchanged four times. After washing and drying, the product was impregnated with a silver nitrate solution having a concentration of 0.05% by weight for 6 h in an equal volume, and was then dried at 95°C for 12 h. Then, pseudoboehmite and dilute nitric acid (2.5% by weight based on the total weight of the catalyst) were added, and the mixture was shaped into a cylindrical strip having a diameter of 1.5 mm and a length of 3-10 mm. The amount of the pseudoboehmite added was 10% by weight based on the total weight of the catalyst. The shaped product was calcined in air at 525°C for 5 h, and was then used as an alkylation catalyst, which was designated as S1. The content of silver in the catalyst was 0.06%.

[0059] Example 2

[0060] The intermediate product of the molecular sieve prepared in step (1) of Example 1 was subjected to acid exchange, washing, and drying under the same conditions as in Example 1, and was then impregnated with a silver nitrate solution having a concentration of 0.10% by weight for 6 h in an equal volume, and was then dried at 95°C for 12 h. The shaped product was prepared under the same conditions as in Example 1, and was then used as an alkylation catalyst, which was designated as S2. The content of silver in 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. Then, silver nitrate solution with a weight percentage concentration of 0.20% was added, and the mixture was impregnated by equal volume for 6 hours, followed by drying at 95°C for 12 hours. The molding process conditions were the same as in Example 1, and the resulting alkylation catalyst was designated S3, with a silver content of 0.24%.

[0063]

Example 4

[0064] The molecular sieve intermediate prepared in step (1) of Example 1 was exchanged in 0.1 mol / L hydrochloric acid solution at 80°C for 5 hours per exchange, for a total of 4 exchanges. After washing and drying, copper nitrate solution with a weight percentage concentration of 0.19% was added and impregnated by equal volume for 6 hours, followed by drying at 95°C for 12 hours. Then, boehmite and dilute nitric acid were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of boehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was calcined in air at 525°C for 5 hours to prepare an alkylation catalyst, designated S4, with a copper content of 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. A copper nitrate solution with a weight percentage concentration of 0.37% was added, and the mixture was impregnated by equal volume for 6 hours, followed by drying at 95°C for 12 hours. The molding process conditions were the same as in Example 4, and the resulting alkylation catalyst was designated S5, with a copper content of 0.24%.

[0067]

Example 6

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

[0069] The alkylation catalyst prepared in Example 6, designated S6, contains 0.12% silver.

[0070]

Example 7

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

[0072] The alkylation catalyst prepared in Example 7, designated S7, contains 0.12% silver.

[0073]

Example 8

[0074] (1) Add 4.1g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g cetyltrimethylammonium bromide (CTAB) to 139.8g water. After thorough dissolution and mixing, add 18.0g silica powder and stir vigorously. Then add 9.0g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 155℃, the crystallization time is 84 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water and dry for later use. 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 determined to be 24.3, thickness 5.0–7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, silver nitrate solution with a weight percentage concentration of 0.10% was added and impregnated by equal volume for 6 h, followed by drying at 95 °C for 12 h. Then, boehmite and dilute nitric acid (2.5%) were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of boehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was calcined in air at 525 °C for 5 h to obtain the alkylation catalyst, designated S8, with a silver content of 0.12%.

[0076]

Example 9

[0077] (1) Add 2.5g NaOH, 13.4g hexamethyleneimine (HMI), and 2.18g cetyltrimethylammonium bromide (CTAB) to 121.8g water. After thorough dissolution and mixing, add 18.0g silica powder, stir vigorously, and then add 5.6g aluminum nitrate nonahydrate. Aging at room temperature for 6 hours is carried out, followed by crystallization in a high-pressure cryogenic chamber lined with polytetrafluoroethylene. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, 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 determined to be 38.9, thickness 5.0–7.5 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, silver nitrate solution with a weight percentage concentration of 0.10% was added and impregnated by equal volume for 6 h, followed by drying at 95 °C for 12 h. Then, pseudoboehmite and dilute nitric acid (2.5%) were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was calcined in air at 525 °C for 5 h to obtain the alkylation catalyst, designated S9, with a silver content of 0.12%.

[0079]

Example 10

[0080] (1) Add 3.6g NaOH, 10.2g hexahydropyridine (PI, piperidine), and 1.4g cetyltrimethylammonium chloride (CTAC) to 139.1g water. After thorough dissolution and mixing, add 18.0g silica powder, stir vigorously, and then add 7.5g aluminum nitrate nonahydrate. Aging at room temperature for 6 hours is carried out, followed by crystallization in a high-pressure cryogenic chamber lined with polytetrafluoroethylene. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, 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 determined to be 24.7, thickness 5.0–10.0 nm) was exchanged in 0.1 mol / L hydrochloric acid solution at 80 °C for 5 h / time, for a total of 4 exchanges. After washing and drying, silver nitrate solution with a weight percentage concentration of 0.10% was added and impregnated by equal volume for 6 h, followed by drying at 95 °C for 12 h. Then, boehmite and dilute nitric acid (2.5%) were added to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of boehmite added was 10% of the total weight of the catalyst on a dry basis. The catalyst was calcined in air at 525 °C for 5 h to obtain an alkylation catalyst, designated S10, with a silver content of 0.12%.

[0082]

Example 11

[0083] The only difference from Example 2 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, designated S11, contains 0.12% silver.

[0085] Comparative Example 1

[0086] (1) Add 3.6g NaOH, 11.9g hexamethyleneimine (HMI), and 1.6g cetyltrimethylammonium bromide (CTAB) to 139.1g water. After thorough dissolution and mixing, add 18.0g silica powder and stir vigorously. Then add 7.5g aluminum nitrate nonahydrate and age at room temperature for 6 hours. Transfer the mixture to a high-pressure cryogenic chamber lined with polytetrafluoroethylene for crystallization. The crystallization temperature is 165℃, the crystallization time is 96 hours, and the rotation speed is 40 rpm. After crystallization, wash with pure water and dry for later use. The synthesis ratio of the above molecular sieve is: 1SiO2:1 / 30Al2O3:0.10OH - :25H2O:0.40HMI:0.015CTAB.

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

[0088] Comparative Example 2

[0089] Citing CN 104513122A (CN201310450053.9) Method for synthesizing cyclohexylbenzene by liquid-phase alkylation of benzene and cyclohexene.

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

[0091] (Comparative Example 3)

[0092] Reference CN 104510123A (CN201310451337.X) Method for synthesizing cyclohexylbenzene by liquid-phase alkylation of benzene and cyclohexene.

[0093] Commercially available USY-type molecular sieve (SiO2 / Al2O3 = 6.1), pseudoboehmite, and dilute nitric acid were mixed and molded to form catalyst cylindrical strips with a diameter of 1.5 mm and a length of 3–10 mm. The amount of pseudoboehmite added was calculated on a dry basis and accounted for 25% of the total weight of the catalyst. The mixture was calcined in air at 525 °C for 5 h to produce alkylation catalyst C3.

[0094] Comparative Example 4

[0095] The only difference from Example 1 is that equimolar dipentyldimethylammonium iodide (DPenDMAI) is used instead of hexadecyltrimethylammonium bromide (CTAB).

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

[0097]

Application Example 1

[0098] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene in the presence of hydrogen and catalyzed by the catalyst described above. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkalis using 13X molecular sieves and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 10. The water content, total nitrogen content, and total sulfur content of the raw materials were 15 mg / kg, 0.03 mg / kg, and 0.05 mg / kg, respectively. The catalysts prepared in Examples 1-11 and Comparative Examples 1-4 were loaded into fixed-bed reactors at a loading of 3.0 g. Pre-reduction was first performed under atmospheric pressure and hydrogen conditions at 250°C for 4 h. The temperature was then lowered to 130°C, the pressure increased to 2.0 MPa, and the pretreated raw materials were introduced at a hydrogen / benzene molar ratio of 0.5 at a flow rate of 6.0 g / h (i.e., a raw material space velocity of 2.0 h⁻¹). -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 1.

[0099] Table 1

[0100]

[0101]

[0102] *Data from a 72-hour reaction time.

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

[0104]

Application Example 2

[0105] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene in the presence of hydrogen and catalyzed by the catalyst described above. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkalis using 13X molecular sieves and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 12.5. The water content, total nitrogen content, and total sulfur content of the raw materials were 56 mg / kg, 0.05 mg / kg, and 0.07 mg / kg, respectively. The catalysts prepared in Examples 2 and Comparative Examples 1 and 4 were loaded into fixed-bed reactors and pre-reduced under atmospheric pressure and hydrogen conditions at 200°C for 3 hours. The temperature was then lowered to 140°C, the pressure increased to 2.5 MPa, and the pre-treated raw materials were introduced at a hydrogen / benzene molar ratio of 0.4 at a flow rate of 12.0 g / h (i.e., a raw material space velocity of 4.0 h⁻¹). -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 2.

[0106] Table 2

[0107]

[0108] *Data from a 72-hour reaction time.

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

[0110]

Application Example 3

[0111] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene in the presence of hydrogen and catalyzed by the catalyst described above. The raw materials, benzene and cyclohexene, were pretreated with 13X molecular sieves for dehydration and removal of alkalis, and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 20. The water content, total nitrogen content, and total sulfur content of the raw materials were 15 mg / kg, 0.03 mg / kg, and 0.05 mg / kg, respectively. The catalysts prepared in Examples 2 and Comparative Examples 1 and 4 were loaded into fixed-bed reactors at a loading of 3.0 g. Pre-reduction was first performed under atmospheric pressure and hydrogen conditions at 400°C for 2 h. The temperature was then lowered to 180°C, the pressure increased to 3.0 MPa, and the pretreated raw materials were introduced at a hydrogen / benzene molar ratio of 0.8 at a flow rate of 6.0 g / h (i.e., a raw material space velocity of 2.0 h⁻¹). -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 3.

[0112] Table 3

[0113]

[0114] *Data from a 72-hour reaction time.

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

[0116]

Comparative Application Example 1

[0117] Cyclohexylbenzene was prepared by alkylation of benzene and cyclohexene under the catalysis of the catalyst described above, without the addition of hydrogen. The raw materials, benzene and cyclohexene, were pretreated by dehydration and removal of alkali using 13X molecular sieves, and then thoroughly mixed. The molar ratio of benzene to cyclohexene was 10. The water content, total nitrogen content, and total sulfur content of the raw materials were 15 mg / kg, 0.03 mg / kg, and 0.05 mg / kg, respectively. The catalysts prepared in Examples 2 and Comparative Examples 1 and 4 were loaded into fixed-bed reactors at a loading rate of 3.0 g. The temperature was adjusted to 130°C, and the pressure was increased to 2.0 MPa. The pretreated raw materials were then introduced at a flow rate of 6.0 g / h, i.e., a raw material space velocity of 2.0 h⁻¹. -1 The reaction products were analyzed and calculated using gas chromatography, and the results are shown in Table 4.

[0118] Table 4

[0119]

[0120] *Data from a 72-hour reaction time.

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

[0122] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing cyclohexylbenzene, which comprises using benzene and cyclohexene as raw materials, using a metal / MWW molecular sieve as a catalyst, and allowing an alkylation reaction to occur in a hydrogen atmosphere to produce cyclohexylbenzene, wherein, The molar ratio of hydrogen to benzene is 0.1-1.0, the temperature of the alkylation reaction is 80-200 °C, and the pressure of the alkylation reaction is 1.0-4.0 MPa; the catalyst is subjected to pre-reduction before the alkylation reaction, the reducing gas is hydrogen, the pre-reduction temperature is 100-400 °C, and the pre-reduction time is 0.1-10 h; the molar ratio of SiO2 / Al2O3 of the MWW molecular sieve is 10-100, the lamellar thickness of the MWW molecular sieve is 5-10 nm, and the metal is copper and / or silver.

2. The production method according to claim 1, characterized by, The molar ratio of hydrogen to benzene is 0.2-0.

6.

3. The production method according to claim 1, characterized by, The method uses a fixed bed reactor.

4. The production method according to claim 1, characterized by, the temperature of the alkylation reaction is 110 to 150 °C; and / or, the total mass hourly space velocity of benzene to cyclohexene is 0.1 to 6.0 h -1 ; and / or, the pressure of the alkylation reaction is 1.5 to 2.5 MPa.

5. The production method according to claim 4, characterized by, The total mass space velocity of benzene to cyclohexene is 1.0-4.0 h -1 .

6. The production method according to claim 1, characterized by, The pre-reduction temperature is 150-300 °C, and the pre-reduction time is 1-5 h.

7. The production method according to claim 1, characterized by, The molar ratio of benzene to cyclohexene is 3-30; and / or, the water content in the raw benzene and cyclohexene is <100 mg / kg, the total nitrogen content is <0.1 mg / kg, and the total sulfur content is <0.1 mg / kg.

8. The production method according to claim 7, characterized by, The molar ratio of benzene to cyclohexene is 5-15; and / or, the water content in the raw benzene and cyclohexene is <50 mg / kg, the total nitrogen content is <0.05 mg / kg, and the total sulfur content is <0.05 mg / kg.

9. The production method according to claim 1, characterized by, The benzene and cyclohexene raw materials are subjected to dehydration and alkaline substance removal treatment before the reaction.

10. The method of claim 1, wherein The molar ratio of SiO2 / Al2O3 of the MWW molecular sieve is 20-40.

11. The preparation method according to claim 1, characterized in that, In the catalyst, the content of the metal, calculated as an element, is 0.01%-1.00% based on the weight of the catalyst, and the content of the MWW molecular sieve is 80%-95%.

12. The preparation method according to claim 11, characterized in that, In the catalyst, the content of the metal, calculated as an element, is 0.05%-0.30%.

13. The preparation method according to claim 1, characterized in that, The catalyst includes a binder, and the content of the binder, calculated as an oxide, is 5%-20% based on the weight of the catalyst; the binder is at least one of alumina and silica.

14. The preparation method according to claim 13, characterized in that, The catalyst includes a binder, and the content of the binder, calculated as an oxide, is 5%-20% based on the weight of the catalyst; the binder is at least one of alumina and silica.

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