A catalyst, a preparation method thereof, and an application thereof in the liquid-phase alkylation of benzene and cyclohexene to synthesize cyclohexylbenzene

Abstract

The present invention provides a catalyst, a preparation method thereof, and an application thereof in the liquid-phase alkylation of benzene and cyclohexene to synthesize cyclohexylbenzene. The catalyst uses MWW molecular sieve synthesized from inexpensive and low-toxic cyclohexylamine as the active component and silica as the binder. The prepared catalyst exhibits excellent catalytic performance in the liquid-phase alkylation reaction of benzene and cyclohexene.

Description

Technical Field

[0001] The present invention relates to a catalyst, a preparation method thereof, and an application thereof in the liquid-phase alkylation of benzene and cyclohexene to synthesize cyclohexylbenzene, belonging to the field of catalyst preparation. Background Art

[0002] Cyclohexylbenzene is a new type of chemical intermediate and has broad application prospects in industries such as energy, chemical engineering, and environment. The peroxidation reaction of cyclohexylbenzene can be used to synthesize phenol and cyclohexanone. Phenol is a chemical raw material with a large demand, and cyclohexanone is an intermediate for the production of caprolactam and nylon. The traditional cumene peroxidation process for preparing phenol will by-produce a large amount of acetone. Cyclohexylbenzene is an excellent TFT liquid crystal raw material (CN1318617A), and has characteristics such as extremely high chemical stability, photochemical stability, low viscosity, and excellent physical properties. Cyclohexylbenzene is also an excellent additive for lithium-ion battery electrolytes, has overcharge prevention performance, and can significantly improve the safety of the battery (CN1632983A, CN1430306A, CN1475038A), and is one of the key raw materials for electric vehicles. In addition, cyclohexylbenzene is also a high-quality diesel additive.

[0003] The methods for synthesizing cyclohexylbenzene mainly include biphenyl selective hydrogenation method, benzene hydroalkylation method, and benzene alkylation method (reacting benzene with alkylating reagents such as cyclohexene, cyclohexanol, and chlorocyclohexane).

[0004] The biphenyl selective hydrogenation method has a simple process, high product yield, and high purity, but it requires the addition of a solvent, the catalyst is not mature, and the price of biphenyl is relatively high.

[0005] The benzene hydroalkylation process is simple, with high product yields and high purity. Patent US5053571 discloses a process for the hydroalkylation of benzene to synthesize cyclohexylbenzene over a Beta zeolite catalyst loaded with Ru and Ni. Patent US5146024 discloses a process for the hydroalkylation of benzene to prepare cyclohexylbenzene over an X or Y zeolite catalyst loaded with metal Pd, and the catalyst is modified with an alkali metal or a rare earth metal. ExxonMobil uses an MCM-22 family zeolite loaded with Ni, Pd, Pt, or Ru as a catalyst for the hydroalkylation reaction of benzene in a hydrogen atmosphere (CN101687728, CN101754940, CN101796000, CN101925561, CN101998942, CN101998942, CN102015589, CN102177109, CN103261126, US6037513, US7579511, US7847128, US7910778, US8084648, US8106243, US8178728, US8329956, US8519194, US20100191017, US20110015457, US20110288341, and US20120178969). The reaction conditions are: 140 - 175 °C, 0.93 - 1.21 MPa, the molar ratio of hydrogen to benzene is 0.3 - 0.65, and the benzene weight hourly space velocity is 0.26 - 1.05 h -1 . The highest yield of cyclohexylbenzene can reach 40%. Patent US20120157718 discloses a process for hydroalkylation using a Y zeolite catalyst loaded with Ni, Pd, Pt, or Ru. However, the benzene hydroalkylation method faces disadvantages such as low yield, many side reactions, and harsh reaction conditions.

[0006] The alkylation of benzene with cyclohexene, cyclohexanol, chlorocyclohexane, etc. is another important method for synthesizing cyclohexylbenzene. Patent US8598388-B2 discloses a method for synthesizing cyclohexylbenzene by the alkylation of benzene with cyclohexene over a catalyst prepared with Y zeolite (FAU structure) as the active component. Under the conditions of 150 °C and 3.7 MPa and a benzene-to-alkene molar ratio of 10, the conversion of cyclohexene can reach 99.6%, the selectivity of cyclohexylbenzene can reach 87.7%, and the selectivity of cyclohexylbenzene and polysubstituted cyclohexylbenzene can reach 98.3% (US8598388-B2). Patents (CN104513123B and US20120157718) disclose methods for synthesizing cyclohexylbenzene by the alkylation of benzene with cyclohexene over an FAU zeolite catalyst. Patent (CN106518600B) discloses a method for catalyzing the alkylation of benzene and cyclohexene with a catalyst composed of Beta zeolite and a binder. Patent (CN105367371B) discloses a method for catalyzing the liquid-phase alkylation of benzene and cyclohexene with a catalyst composed of organosilicate microporous zeolite and a binder. Although FAU and *BEA zeolites exhibit excellent catalytic performance in this reaction, they face the problem of rapid deactivation.

[0007] In this reaction, ionic liquids are also an important type of catalyst. The ionic liquid formed by triethylamine hydrochloride and ZnCl2 exhibits high catalytic activity in the alkylation reaction of benzene with cyclohexene. Under the conditions of 80 °C and a benzene-to-alkene molar ratio of 15, after reacting for 10 min, the conversion of cyclohexene is close to 100%, and the selectivity of cyclohexylbenzene is 89.6% (Fine Chemicals, 2008, 405 - 408). The Lewis acid ionic liquid prepared from 1-butyl-3-methylimidazolium salt ([bmin]Br or [bmin]Cl) and inorganic chloride can catalyze the alkylation reaction of benzene and cyclohexene, among which [bmin]Br-AlCl3 has the best catalytic effect. Under the conditions of 80 °C and a benzene-to-alkene molar ratio of 8, the yield of cyclohexylbenzene is as high as 86.8% after reacting for 1 h (Spectroscopy Laboratory, 2011, 28, 2480 - 2483). Ionic liquids are expensive, a large amount is required for the reaction, and subsequent separation problems are faced. Ionic liquids are unstable and easily decompose when exposed to water, and the prepared catalyst cannot be regenerated. The above factors limit their industrial application in the alkylation process of benzene with cyclohexene.

[0008] Patent CN1982264A discloses a method for synthesizing cyclohexylbenzene by the alkylation reaction of benzene and chlorocyclohexane. Patent CN1982263A discloses a method for synthesizing cyclohexylbenzene by the alkylation reaction of benzene and cyclohexanol. The prices of chlorocyclohexane and cyclohexanol are relatively high, and the catalysts used are highly corrosive to the reaction equipment. Summary of the Invention

[0009] The present invention provides a method for preparing an MWW molecular sieve catalyst for liquid-phase alkylation of benzene and cyclohexene. The method uses an MWW molecular sieve synthesized with a cheap and low-toxic cyclohexylamine template as the active component, and obtains a hydrogen-type catalyst through processes such as shaping, drying, calcining to remove the template, ion exchange, and calcination. Then, cyclohexylbenzene and dicyclohexylbenzene are obtained through the alkylation reaction of benzene and cyclohexene on the catalyst.

[0010] According to one aspect of the present application, there is provided a method for preparing a catalyst, which at least includes the following steps:

[0011] Mix the raw materials containing MWW molecular sieve powder, binder and talc powder with water, shape, dry, calcine I, ion exchange, and calcine II to obtain the catalyst.

[0012] The binder is selected from silica or silica sol;

[0013] The mass ratio of the MWW molecular sieve powder to the binder is 9-18:2-11;

[0014] The mass of the talc powder is 1-10 wt% of the total mass of the MWW molecular sieve powder and the binder.

[0015] That is, the MWW molecular sieve powder, binder and talc powder account for 45-90 wt%, 10-55 wt%, and 1-10 wt% of the dry basis mass of the shaped catalyst.

[0016] The MWW molecular sieve powder refers to the MWW molecular sieve powder from which water has been removed after calcination.

[0017] The process of calcination I includes: in an air atmosphere, heating at a heating rate of 0.5-3 °C / min to 440-530 °C and holding for 3-24 h.

[0018] The process of ion exchange includes: exchanging with an exchange solution, and then drying at a temperature of 80-130 °C;

[0019] The exchange solution is selected from solutions of oxalic acid, hydrochloric acid, ammonium chloride or ammonium nitrate.

[0020] The process of calcination II includes: in an air atmosphere, heating at a heating rate of 0.5-3 °C / min to 440-530 °C and holding for 1-5 h.

[0021] According to another aspect of the present application, there is provided a catalyst, characterized in that it is prepared by the above preparation method.

[0022] According to another aspect of the present application, there is provided a method for liquid-phase alkylation of benzene and cyclohexene to synthesize cyclohexylbenzene, which at least includes the following steps:

[0023] The raw material containing benzene and cyclohexene is contacted with a catalyst to react and obtain a product containing cyclohexylbenzene and dicyclohexylbenzene;

[0024] The catalyst is selected from the above-mentioned catalysts.

[0025] The molar ratio of benzene to cyclohexene is 2 to 20;

[0026] The mass space velocity of cyclohexene is 0.1 to 8.0 h -1 ;

[0027] The reaction temperature is 120-260°C;

[0028] The reaction pressure is 0.5-5.0 MPa.

[0029] Specifically, it includes:

[0030] 1. MWW molecular sieve raw powder synthesized by cheap and low-toxic cyclohexylamine template, SiO2 binder (silica sol solution, SiO2 content is 30.46wt.%), sesbania powder and appropriate amount of water are fully mixed and molded, wherein the content of each component is:

[0031] a) The dry weight of the MWW molecular sieve raw powder accounts for 45% to 90% of the dry weight of the formed catalyst;

[0032] b) SiO2 binder (silica sol solution, SiO2 content of 30.46wt.%) accounts for 10% to 55% of the dry weight of the formed catalyst;

[0033] c) sesbania powder accounts for 1% to 10% of the dry weight of the shaped catalyst;

[0034] 2. Slowly increase the temperature (0.5-3°C / min) to 440-530°C in a flowing air atmosphere and maintain for 3-24 hours to remove the template.

[0035] 3. The calcined sample is exchanged with oxalic acid, hydrochloric acid, ammonium chloride or ammonium nitrate solution and then dried at 80℃~130℃.

[0036] 4. The exchanged sample is slowly heated (0.5-3°C / min) to 440-530°C under a flowing air atmosphere and maintained for 1-5 hours to obtain a hydrogen sample.

[0037] 5. Carry out liquid phase alkylation reaction of benzene and cyclohexene on the obtained hydrogen catalyst. The reaction conditions are: reaction temperature 120-260°C, reaction pressure 0.5-5.0MPa, benzene / cyclohexene 2-20, cyclohexene mass space velocity 0.1-8.0h -1 .

[0038] The advantages of this application are as follows: Using the MWW molecular sieve synthesized with cheap and low-toxic cyclohexylamine as the template agent as the active component, through processes such as shaping, calcination to remove the template agent, ion exchange, and calcination, a hydrogen-type catalyst is obtained. Then, cyclohexylbenzene is obtained by the alkylation reaction of benzene and cyclohexene on the catalyst. Description of the Drawings

[0039] Figure 1 It is the pyridine infrared characterization results of the sample obtained in Example 1 (HMCM-49-SiO2) and the sample obtained in Comparative Example 1 (HMCM-49-Al2O3).

[0040] Figure 2 It is the dynamic adsorption results of benzene on the sample obtained in Example 1 (HMCM-49-SiO2) and the sample obtained in Comparative Example 1 (HMCM-49-Al2O3) at 20 Pa. Detailed Embodiments

[0041] The following uses examples to further illustrate the present invention, but the examples do not limit the content of the present invention.

[0042] Example 1

[0043] 95.51 g of MWW molecular sieve raw powder (dry basis 89%), 49.24 g of silica sol solution (SiO2 content is 30.46 wt.%), 3 g of sesbania powder, and an appropriate amount of water are fully mixed and then extruded into shape. It is dried overnight at 120 °C. Then, it is heated to 440 °C at a rate of 1.5 °C / min and maintained for 6 h to remove the cyclohexylamine template agent. Ion exchange is carried out with 0.8 mol / L ammonium nitrate solution, repeated three times. After drying at 120 °C, it is heated to 500 °C at a rate of 1.5 °C / min and maintained for 3 h. Thus, a hydrogen-type shaped catalyst with MWW molecular sieve as the active component and a dry basis content of 85% is obtained.

[0044] Example 2

[0045] 78.65 g of MWW molecular sieve raw powder (dry basis 89%), 98.49 g of silica sol solution (SiO2 content is 30.46 wt.%), 3 g of sesbania powder, and an appropriate amount of water are fully mixed and then extruded into shape. It is dried overnight at 120 °C. Then, it is heated to 480 °C at a rate of 1 °C / min and maintained for 6 h to remove the cyclohexylamine template agent. Ion exchange is carried out with 0.8 mol / L ammonium chloride solution, repeated three times. After drying at 120 °C, it is heated to 500 °C at a rate of 1 °C / min and maintained for 3 h. Thus, a hydrogen-type shaped catalyst with MWW molecular sieve as the active component and a dry basis content of 70% is obtained.

[0046] Example 3

[0047] 56.18 g of as - prepared MWW zeolite powder (dry - basis 89%), 164.15 g of silica sol solution (SiO₂ content 30.46 wt.%), 3 g of sesbania powder, and appropriate amount of water were fully mixed and then extruded into pellets. Dried overnight at 120 °C. Then, heated to 520 °C at a rate of 2.5 °C / min and held for 6 h to remove the cyclohexylamine template. Ion - exchanged with 0.8 mol / L hydrochloric acid solution for three times. After drying at 120 °C, heated to 500 °C at a rate of 2.5 °C / min and held for 3 h. Thus, a hydrogen - type shaped catalyst with MWW zeolite as the active component and a dry - basis content of 50% was obtained.

[0048] Comparative Example 1

[0049] 95.51 g of as - prepared MWW zeolite powder (dry - basis 89%), 20.58 g of pseudo - boehmite (dry - basis 72.9%), 3 g of sesbania powder, and appropriate amount of nitric acid solution (mass fraction 10%) were fully mixed and then extruded into pellets. Dried overnight at 120 °C. Then, heated to 520 °C at a rate of 2.5 °C / min and held for 6 h to remove the cyclohexylamine template. Ion - exchanged with 0.8 mol / L ammonium nitrate solution for three times. After drying at 120 °C, heated to 500 °C at a rate of 2.5 °C / min and held for 3 h. Thus, a hydrogen - type shaped catalyst with MWW zeolite as the active component and a dry - basis content of 85% was obtained.

[0050] Test Example

[0051] 1.0 g of the catalyst prepared by the above method was loaded into a fixed - bed reactor, and then a mixed feed of benzene and cyclohexene was introduced. Under the conditions of 160 °C, 3.0 MPa, benzene / cyclohexene = 6, and cyclohexene mass hourly space velocity = 4 h -1 The liquid - phase alkylation reaction of benzene and cyclohexene was carried out. The results after 24 h of reaction are listed in Table 1.

[0052] Table 1

[0053]

[0054] The acidity of the zeolite catalyst and the diffusion performance of the reactants inside the crystal are important factors affecting its catalytic performance. Therefore, the acidity of the sample and the diffusion performance of benzene molecules were analyzed by pyridine - IR and IGA intelligent gravimetric sorption analyzer.

[0055] The infrared test method for adsorbed pyridine is as follows: The sample was made into a thin slice with a diameter of 1.3 cm and a density of 7.5 mg / cm 2 and placed in an infrared cell. Pretreated at 450 °C and 10 -2 Pa for 1 h. After cooling to room temperature, pyridine was adsorbed, and then physical adsorption and pyridine in the gas phase were removed at 150 °C for 0.5 h. After cooling to room temperature, the spectrum was collected, asFigure 1 As shown, calculate and the amount of Lewis acid. The and the amount of Lewis acid of the sample (HMCM-49-SiO2) obtained in Example 1 are 0.107 mmol / g and 0.040 mmol / g respectively. Therefore, its / Lewis ratio is 2.637. The and the amount of Lewis acid of the sample (HMCM-49-Al2O3) obtained in Comparative Example 1 are 0.066 mmol / g and 0.048 mmol / g respectively. Therefore, its / Lewis ratio is 1.368.

[0056] The gravimetric adsorption process of benzene measured by a smart gravimetric sorption analyzer at 40 °C is as follows: 50 mg of the sample is placed in the sample cell and pretreated at 300 °C and 10 -3 Pa for 2 h. When the temperature is lowered to 40 °C, benzene is introduced into the sample cell, and the benzene vapor pressure is controlled at 20 Pa by a pressure sensor. Its dynamic adsorption process is as Figure 2 shown. The time required for benzene to reach equilibrium on the sample (HMCM-49-SiO2) obtained in Example 1 is 47 min, while the time required for benzene to reach equilibrium on the sample (HMCM-49-Al2O3) obtained in Comparative Example 1 is 71 min. Therefore, the diffusion rate of benzene on the sample obtained in Example 1 (using silica as the binder) is faster.

[0057] From the results of infrared characterization and analysis by the smart gravimetric sorption analyzer, it can be seen that compared with the sample formed with an alumina binder (Comparative Example 1), the sample formed with a silica binder has more acid sites, a larger / Lewis value, and a faster diffusion rate of benzene inside its crystal. Therefore, the sample formed with a silica binder has more excellent catalytic performance in the liquid-phase alkylation reaction of benzene and cyclohexene.

[0058] The above are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for synthesizing cyclohexylbenzene by liquid-phase alkylation of benzene and cyclohexene, characterized in that, At least include the following steps: Contact a raw material containing benzene and cyclohexene with a catalyst and react to obtain a product containing cyclohexylbenzene and dicyclohexylbenzene; The preparation method of the catalyst at least includes the following steps: Mix a raw material containing MWW zeolite raw powder, binder and phthalic anhydride with water, form, dry, calcine I, ion exchange, and calcine II to obtain the catalyst; The binder is selected from at least one of silica or silica sol; The mass ratio of the MWW zeolite raw powder to the binder is 9-18:2-11; The mass of the phthalic anhydride is 1-10 wt% of the total mass of the MWW zeolite raw powder and the binder; The ion exchange process includes: exchanging with an exchange solution and then drying at a temperature of 80-130°C; The exchange solution is selected from solutions of oxalic acid, hydrochloric acid, ammonium chloride or ammonium nitrate.

2. The method according to claim 1, wherein The calcination I process includes: heating to 440-530°C at a heating rate of 0.5-3°C / min in an air atmosphere and holding for 3-24 h.

3. The method according to claim 1, wherein The calcination II process includes: heating to 440-530°C at a heating rate of 0.5-3°C / min in an air atmosphere and holding for 1-5 h.

4. The method according to claim 1, characterized in that, The molar ratio of benzene to cyclohexene is 2-20; The mass hourly space velocity of the cyclohexene is 0.1 to 8.0 h -1 ; The temperature of the reaction is 120-260°C; The pressure of the reaction is 0.5-5.0 MPa.

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