A catalyst system and a process for the preparation of cyclohexanol

Abstract

The present application relates to the technical field of cyclohexanol preparation, and particularly discloses a catalyst system and a method for preparing cyclohexanol by using the catalyst system. The catalyst system is prepared by mixing silica and chlorosulfonic acid in an organic solvent, stirring and reacting at room temperature until no gas is emitted, and then separating and drying the solid, wherein the specific surface area of the silica is 100-400 m 2 / g; the weight ratio of the silica to the chlorosulfonic acid is 50:5-15. The catalyst system provided by the present application can achieve a high conversion rate of cyclohexene and a high yield of cyclohexanol in the reaction process of preparing cyclohexanol by indirect hydration of cyclohexene, and the selectivity of the cyclohexanol can reach more than 90%. Moreover, the preparation method is simple in process, high in economic benefit, and convenient for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cyclohexanol preparation, and particularly relates to a catalyst system and a method for preparing cyclohexanol. BACKGROUND

[0002] Cyclohexanol is an important raw material for producing adipic acid, hexamethylene diamine, cyclohexanone, caprolactam and the like, and is widely used in the fields of organic synthesis, paint, dye, medicine and the like. The industrial synthesis methods of cyclohexanol mainly include phenol hydrogenation method, cyclohexane oxidation method and cyclohexene hydration method. The cyclohexene hydration method has the advantages of high conversion rate, low energy consumption, high safety and the like, and is a widely used method for preparing cyclohexanol in the industry at present. The cyclohexene hydration method is divided into direct hydration and indirect hydration. The conversion rate of cyclohexene in the direct hydration method is relatively low, while the indirect hydration method of cyclohexene is composed of two steps of cyclohexene esterification with carboxylic acid and hydrolysis of cyclohexyl carboxylate, and has the advantages of high conversion rate of cyclohexene and high selectivity of cyclohexanol, and is an extremely promising method for synthesizing cyclohexanol.

[0003] The esterification of cyclohexene with carboxylic acid in the indirect hydration method of cyclohexene is an acid catalysis reaction, and a strong acid catalyst is required, while the hydrolysis of cyclohexyl carboxylate is relatively easy to occur and can occur under the action of acid or alkaline catalysts. Therefore, it is of great significance to develop a strong acid catalyst with simple preparation and high performance for application in the process of preparing cyclohexanol by indirect hydration of cyclohexene.

[0004] In the prior art research, there is a report that HZSM-5 molecular sieve is used as a catalyst to explore the indirect hydration reaction of cyclohexene, and the yield of cyclohexanol can reach 40% (Journal of Hebei University of Technology, 2012, 41 (04): 34-39). Chinese patent application CN102875371A discloses a method for synthesizing cyclohexyl acetate from cyclohexene by using a sulfonic acid group cation exchange resin as a catalyst, and CN107935845A discloses a method for preparing cyclohexyl acetate by reaction rectification, which uses an alkane or cycloalkane with a boiling point of A as a solvent, and a macroporous strong acid hydrogen type ion exchange resin and the like as a catalyst. Although the catalysts have excellent catalytic effect, the resin catalysts are easy to swell in organic solvents, the catalysts are relatively high in price, and the use of organic solvents increases the reaction cost. Recently, it is reported in a literature that a sulfonic acid group is introduced into SBA-15 to prepare SBA-15-SO3H catalyst and the catalyst is used in the esterification of cyclohexene with formic acid, and the conversion rate of cyclohexene is 54.4%. The next year, it is reported in a literature that three kinds of MIL-101(Cr)-SO3H catalysts are prepared and used in the esterification of cyclohexene with formic acid, and the optimal conversion rate of cyclohexene is 64.0%. Although the above catalysts have a certain catalytic effect on the conversion of cyclohexene, the conversion rate of cyclohexene and the selectivity of cyclohexanol are not high. In order to improve the conversion rate of cyclohexene and the selectivity, and improve the yield of cyclohexanol, it is still necessary to develop a high-catalytic-activity catalyst system. SUMMARY

[0005] In order to solve the problem of low conversion rate of cyclohexene and selectivity and yield of cyclohexanol in the existing indirect hydration of cyclohexene, the application aims to provide a catalytic system suitable for preparing cyclohexanol by indirect hydration of cyclohexene, which is obtained by reacting chlorosulfonic acid and silicon dioxide to introduce sulfonic acid groups on the surface of silicon dioxide as a catalyst for the indirect hydration of cyclohexene, and is applied to the esterification of cyclohexene and carboxylic acid and the hydrolysis of cyclohexyl carboxylate, so that a higher conversion rate of cyclohexene and selectivity and yield of cyclohexanol can be obtained.

[0006] The application provides the following technical scheme:

[0007] A catalyst system is obtained by mixing silicon dioxide and chlorosulfonic acid in an organic solvent, stirring and reacting at room temperature until no gas is emitted, and then separating and drying the solid, wherein:

[0008] The specific surface area of the silicon dioxide is 100-400 m 2 / g.

[0009] The weight ratio of the silicon dioxide to the chlorosulfonic acid is 50:5-15.

[0010] The catalyst system of the application is obtained by reacting silicon dioxide and chlorosulfonic acid in an organic solvent at room temperature (16-26 ℃) to introduce sulfonic acid groups on the surface of the silicon dioxide to form SiO2-SO3H, and the silicon dioxide and the sulfonic acid are used to play a synergistic effect to catalyze the reaction of cyclohexene and carboxylic acid to form cyclohexyl carboxylate and the hydrolysis of cyclohexyl carboxylate, so that a high conversion rate of cyclohexene and a high yield of cyclohexanol can be obtained. It should be noted that experimental research shows that the specific surface area of the silicon dioxide and the amount of the silicon dioxide and the chlorosulfonic acid have an important influence on the catalytic effect of the prepared catalyst system, which may be due to the fact that they affect the distribution of the sulfonic acid groups on the surface of the silicon dioxide and then affect the catalytic effect on the indirect hydration of cyclohexene, so it is necessary to control them within a suitable range to be suitable for the esterification of cyclohexene and carboxylic acid, especially the hydrolysis of cyclohexyl carboxylate.

[0011] As a preferred embodiment of the application,

[0012] The organic solvent is selected from n-hexane, dichloromethane, cyclohexane, benzene, toluene, xylene or petroleum ether. The organic solvent should immerse the silicon dioxide, and the mass ratio of the organic solvent to the silicon dioxide is preferably 4-10:1.

[0013] A preparation method of cyclohexanol by indirect hydration of cyclohexene comprises the following steps:

[0014] (1) preparing cyclohexyl carboxylate by esterifying cyclohexene and carboxylic acid

[0015] The cyclohexene, carboxylic acid and the above catalyst system are sequentially added into a reaction kettle, the reaction temperature is controlled at 40-180°C, preferably 80-180°C, and the reaction is stirred for 1-12 h, preferably 4-12 h, to obtain carboxylic acid ester after the reaction;

[0016] (2) Hydrolysis of carboxylic acid ester to prepare cyclohexanol

[0017] The carboxylic acid ester in step (1) is separated, and then mixed with water and the above catalyst system, and the temperature is controlled at 80-180°C, and the reaction is stirred for 1-10 h, preferably 3-10 h, to obtain cyclohexanol after the reaction.

[0018] The preparation method of the present application separates the preparation of cyclohexene into carboxylic acid cyclohexyl ester and the hydrolysis of carboxylic acid cyclohexyl ester. Cyclohexene is first reacted with carboxylic acid in the presence of the catalyst of the present application to obtain carboxylic acid cyclohexyl ester, as shown in the following formula:

[0019] R is H or CH3;

[0020] Then the carboxylic acid cyclohexyl ester is separated and hydrolyzed in the presence of the catalyst of the present application and water to prepare cyclohexanol, as shown in the following formula:

[0021] R is H or CH3.

[0022] Due to the catalytic effect of the catalyst of the present application and the combination of the step-by-step reaction, cyclohexene has high conversion rate, and the selectivity of cyclohexanol can reach more than 90%, and cyclohexanol has high yield.

[0023] As a preferred method of the present application,

[0024] The carboxylic acid in step (1) is formic acid or acetic acid.

[0025] As a preferred method of the present application,

[0026] The molar ratio of cyclohexene to carboxylic acid in step (1) is 1:1-5, preferably 1:3-5.

[0027] As a preferred method of the present application,

[0028] The mass of the catalyst in step (1) is 1-24% of the mass of cyclohexene, preferably 6-24%.

[0029] As a preferred method of the present application,

[0030] In step (2), the molar ratio of carboxylic acid ester to water added is 1:1-70, preferably 1.5-70.

[0031] As a preferred method of the present application,

[0032] The catalyst is used in an amount of 1-7% of the mass of the carboxylic acid ester.

[0033] A method for preparing cyclohexanol by indirect hydration of cyclohexene, comprising the following steps:

[0034] The cyclohexene, carboxylic acid and the catalyst system are sequentially added into a reactor, the reaction temperature is controlled at 80-180℃, and the reaction is stirred for 2-22 h, preferably 7-22 h, to obtain a carboxylic acid ester after the reaction.

[0035] As a preferred method of the present application,

[0036] The molar ratio of cyclohexene to carboxylic acid is 1:1-5, preferably 1:3-5.

[0037] The mass of the catalyst is 1-24% of the mass of the cyclohexene, preferably 6-24%.

[0038] The catalyst system is used in the catalytic hydrolysis reaction of cyclohexyl carboxylate. Preferably, the cyclohexyl carboxylate is cyclohexyl formate or cyclohexyl acetate. The selectivity of cyclohexanol can be more than 90%.

[0039] The present application has the following advantages:

[0040] The present application provides a catalyst system suitable for preparing cyclohexanol by indirect hydration of cyclohexene. The silica with sulfonic acid groups introduced on the surface obtained by the reaction of chlorosulfonic acid and silica is used as a catalyst for the indirect hydration reaction of cyclohexene, which can obtain a high conversion rate of cyclohexene and a high yield of cyclohexanol, and the selectivity of cyclohexanol is more than 90%. The present application has a high yield of cyclohexanol, a simple preparation method, high economic benefits, and is easy for industrial production. DETAILED DESCRIPTION

[0041] The specific embodiments of the present application are further described below.

[0042] Unless otherwise specified, the raw materials used in the present application can be purchased from the market or are commonly used in the art. Unless otherwise specified, the methods in the following examples are conventional methods in the art.

[0043] Example 1

[0044] (1) Preparation of cyclohexyl formate by esterification of cyclohexene and formic acid

[0045] In a reaction kettle, cyclohexene (5 mol, 411 g), formic acid (20 mol, 923 g), catalyst system 1 (24.6 g) were added in sequence, heated to 80 ℃, stirred for 6 h, cooled to room temperature to obtain cyclohexyl formate, and gas chromatography analysis was performed. The conversion rate of cyclohexene was 98.2%, and the selectivity of cyclohexyl formate was 99.0%.

[0046] (2) Preparation of cyclohexanol by hydrolysis of cyclohexyl formate

[0047] In a reaction kettle, cyclohexyl formate (1 mol, 128 g) synthesized in step (1), water (5 mol, 90 g) were added, heated to 120 ℃, catalyst system 1 (2.56 g) was added, stirred for 3 h, cooled to room temperature to obtain cyclohexanol, and gas chromatography analysis was performed. The conversion rate of cyclohexyl formate was 95.1%, and the yield of cyclohexanol was 94.1%.

[0048] The catalyst system 1 used in the above method was prepared by the following process: 50 parts by weight of silicon dioxide (specific surface area 300 m 2 / g) was mixed with 10 parts of chlorosulfonic acid in an organic solvent, stirred at room temperature (25 ℃) until no HCl gas was released, and then the solid was filtered, washed and dried to obtain a silicon dioxide-sulfonic acid catalyst. By comparison, the yield of cyclohexanol using the above catalyst system 1 and combining with the step-by-step reaction is higher than that using HZM-5 molecular sieve catalyst under the same step-by-step conditions. The final yield of cyclohexanol using HZM-5 molecular sieve is very low, less than 20%.

[0049] Example 2

[0050] (1) Preparation of cyclohexyl acetate by esterification of cyclohexene and acetic acid

[0051] In a reaction kettle, cyclohexene (3 mol, 246.3 g), acetic acid (9 mol, 540 g), catalyst system 2 (49.2 g) were added in sequence, heated to 160 ℃, stirred for 4 h, cooled to room temperature to obtain cyclohexyl acetate, and gas chromatography analysis was performed. The conversion rate of cyclohexene was 58.3%, and the selectivity of cyclohexyl acetate was 95.4%.

[0052] (2) Preparation of cyclohexanol by hydrolysis of cyclohexyl acetate

[0053] In a reaction kettle, cyclohexyl acetate (1 mol, 142 g), water (1.5 mol, 27 g) were added in sequence, heated to 160 ℃, catalyst system 2 (7.1 g) was added, stirred for 5 h, cooled to room temperature, and gas chromatography analysis was performed. The conversion rate of cyclohexyl acetate was 80.4%, and the yield of cyclohexanol was 74.7%.

[0054] The catalyst system 2 used in the above method is prepared by the following process: 50 parts by weight of silica (specific surface area 400 m 2 / g) is mixed with 15 parts of chlorosulfonic acid in an organic solvent, and stirred at room temperature (25°C) until no HCl gas is emitted. The solid is filtered, washed and dried to obtain a silica-sulfonic acid catalyst. By comparison, the yield of cyclohexanol using the above catalyst system 1 in combination with the stepwise reaction is higher than that using HZM-5 molecular sieve catalyst under the same stepwise reaction conditions. The final yield of cyclohexanol using HZM-5 molecular sieve is very low, less than 20%.

[0055] Example 3

[0056] (1) Preparation of cyclohexyl formate by esterification of cyclohexene with formic acid

[0057] In a reaction kettle, cyclohexene (4 mol, 328.4 g), formic acid (20 mol, 923 g), and catalyst system 3 (78.8 g) are sequentially added, heated to 180°C, and stirred for 12 h. After cooling to room temperature, cyclohexyl formate is obtained, and gas chromatography analysis shows that the conversion rate of cyclohexene is 98.2% and the selectivity of cyclohexyl formate is 99.3%.

[0058] (2) Hydrolysis of cyclohexyl formate to prepare cyclohexanol

[0059] In a reaction kettle, cyclohexyl formate (1 mol, 128 g) synthesized in step (1) and water (70 mol, 1260 g) are added, heated to 180°C, and catalyst system 3 (8.96 g) is added. After stirring for 10 h, cyclohexanol is obtained after cooling to room temperature. Gas chromatography analysis shows that the conversion rate of cyclohexyl formate is 99.1% and the yield of cyclohexanol is 98.1%.

[0060] The catalyst system 3 used in the above method is prepared by the following process:

[0061] 50 parts by weight of silica (specific surface area 100 m 2 / g) is mixed with 5 parts of chlorosulfonic acid in an organic solvent, and stirred at room temperature (25°C) until no HCl gas is emitted. The solid is filtered, washed and dried to obtain a silica-sulfonic acid catalyst.

[0062] Example 4

[0063] In a reaction kettle, cyclohexene (5 mol, 411 g), formic acid (20 mol, 923 g), and catalyst system 1 (27.16 g) are sequentially added, heated to 80°C, and stirred for 9 h. After cooling to room temperature, cyclohexanol is obtained, and gas chromatography analysis shows that the conversion rate of cyclohexene is 98.5% and the yield of cyclohexanol is 87.2%.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that the catalyst system used in the two-step reaction is prepared by selecting silica with a specific surface area of 500 m 2 / g, and the rest is the same as Example 1, and finally:

[0066] In step (1), the conversion rate of cyclohexene is 89.0%, and the selectivity of cyclohexyl formate is 78.5%;

[0067] In step (2), the conversion rate of cyclohexyl formate is 87.1%, and the yield of cyclohexanol is 56.0%.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the catalyst system used in the two-step reaction is prepared by selecting silica with a specific surface area of 500 m

[0070] In step (1), the conversion rate of cyclohexene is 99.5%, and the selectivity of cyclohexyl formate is 69.1%;

[0071] In step (2), the conversion rate of cyclohexyl formate is 97.8%, and the yield of cyclohexanol is 76.0%.

[0072] In summary, the catalyst system of the present application is very suitable for application in the esterification reaction of cyclohexene and carboxylic acid, especially in the hydrolysis reaction of cyclohexyl carboxylate, the selectivity of cyclohexanol reaches more than 90%, and the yield of cyclohexanol is high.

Claims

1. A process for the preparation of cyclohexanol by indirect hydration of cyclohexene, characterized in that, The method comprises the following steps: (1) preparing cyclohexyl carboxylate by esterification of cyclohexene and carboxylic acid: adding cyclohexene, carboxylic acid and a catalyst system into a reaction kettle, controlling the reaction temperature at 40-180℃, stirring for 1-12 h, and obtaining cyclohexyl carboxylate after the reaction; (2) preparing cyclohexanol by hydrolysis of cyclohexyl carboxylate: separating the cyclohexyl carboxylate in step (1), then adding water and a catalyst system, controlling the temperature at 80-180℃, stirring for 1-10 h, and obtaining cyclohexanol after the reaction; the catalyst system is obtained by mixing silica and chlorosulfonic acid in an organic solvent, stirring at room temperature until no gas is emitted, then separating the solid and drying, wherein: the weight ratio of silica to chlorosulfonic acid is 50:5-15; The specific surface area of the silica is: 100 to 400 m 2 / g.

2. The process for the preparation of cyclohexanol by indirect hydration of cyclohexene according to claim 1, characterized in that, the organic solvent is selected from n-hexane, dichloromethane, cyclohexane, benzene, toluene, xylene or petroleum ether.

3. The process for the preparation of cyclohexanol by indirect hydration of cyclohexene according to claim 1, characterized in that, The reaction temperature in step (1) is 80-180℃, and the stirring time is 4-12 h; the stirring time in step (2) is 3-10 h.

4. The method of claim 1, wherein, The carboxylic acid in step (1) is formic acid or acetic acid.

5. The method of making according to claim 1 or claim 4, wherein, The molar ratio of cyclohexene to carboxylic acid in step (1) is 1:1-5.

6. The method of making according to claim 1 or claim 4, wherein, The mass of the catalyst in step (1) is 1-24% of the mass of cyclohexene.

7. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of cyclohexyl carboxylate to water is 1:1-70.

8. The production method according to claim 1 or 7, characterized by, In step (2), the amount of catalyst used is 1-7% of the mass of cyclohexyl carboxylate.

9. The process for the preparation of cyclohexanol by indirect hydration of cyclohexene according to claim 1, characterized in that, The method comprises the following steps: adding cyclohexene, carboxylic acid and a catalyst system into a reaction kettle in sequence, controlling the reaction temperature at 80-180℃, stirring for 2-12 h, and obtaining cyclohexyl carboxylate after the reaction, wherein: the molar ratio of cyclohexene to carboxylic acid is 1:1-5; and / or, the mass of the catalyst is 1-24% of the mass of cyclohexene.