Method for preparing cyclohexanol by hydrating cyclohexene

Abstract

The invention provides a method for preparing cyclohexanol by hydrating cyclohexene. According to the method, after the accelerant is introduced into a reaction system for preparing cyclohexanol through cyclohexene hydration, the accelerant can promote cyclohexene and water to generate hydration reaction under the action of the solid acid catalyst to generate cyclohexanol, so that the limitation of chemical equilibrium of chemical reaction of cyclohexene and water is broken through; the conversion per pass of cyclohexene, the selectivity of cyclohexanol and the yield of cyclohexanol are remarkably improved, and the productivity of cyclohexanol products is effectively improved. The method has the advantages that the conversion rate of cyclohexene is high, the selectivity of cyclohexanol is good, the used accelerant is stable and safe, does not react with substances in a reaction system, is convenient to separate, can be recycled for multiple times, is high in practicability, and can be widely applied to industrial production of cyclohexanol.

Description

Technical Field

[0001] The invention relates to the technical field of cyclohexanol preparation, and in particular to a method for preparing cyclohexanol by hydrating cyclohexene. Background Art

[0002] Cyclohexanol is a widely used chemical intermediate, which is mainly used as an intermediate raw material for the production of products such as adipic acid, caprolactam and nylon in industry. In addition, cyclohexanol can also be used in the production of products such as spices, resin paints, insecticides, leather degreasing agents, disinfectants, bactericides and diluents. At present, the production methods of cyclohexanol mainly include phenol hydrogenation to produce cyclohexanol, cyclohexane oxidation to produce cyclohexanol and cyclohexanone, and cyclohexene hydration to produce cyclohexanol. Among them, the cyclohexene hydration method to produce cyclohexanol has the advantages of high selectivity, low hydrogen consumption, high production safety, low investment and environmental friendliness, which has obvious advantages over other methods and is the production method currently commonly used in the production of cyclohexanol.

[0003] However, the process of preparing cyclohexanol by hydration of cyclohexene is limited by chemical equilibrium, and the equilibrium constant is only 5.6 (at 25° C.), which results in a low conversion rate of cyclohexene (about 7-12%). If the reaction conversion rate of cyclohexene is to be improved, it is necessary to cycle through the reaction-separation-reaction-separation method for many times, and the multiple cycle operation will lead to problems such as high energy consumption and low production efficiency. Therefore, how to break the limitation of chemical equilibrium during the reaction process, make the chemical reaction continue to proceed in the positive direction, and break through the technical bottleneck of low per-pass conversion rate of cyclohexene has become a key research topic for researchers. Summary of the invention

[0004] In order to improve the technical problems of low cyclohexene per-pass conversion rate, low cyclohexanol yield, high energy consumption of production process, low production efficiency and the like in the prior art of preparing cyclohexanol by hydration of cyclohexene, the present invention provides a method for preparing cyclohexanol by hydration of cyclohexene. The method is to introduce a promoter into the reaction system of preparing cyclohexanol by hydration of cyclohexene, and the introduction of the promoter can transfer the cyclohexanol generated in the pores of the solid acid catalyst in the reaction system, so that the chemical reaction of preparing cyclohexanol by hydration of cyclohexene continues to proceed in the positive direction, breaking the limitation of chemical equilibrium, and breaking through the technical bottlenecks of low cyclohexene per-pass conversion rate, low cyclohexanol yield, high energy consumption of production process and low production efficiency.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for preparing cyclohexanol by hydrating cyclohexene, the method comprising the following steps:

[0007] Adding a solid acid catalyst, cyclohexene, a promoter and water into a reactor to carry out a hydration reaction to prepare the cyclohexanol;

[0008] Wherein, the promoter is selected from ketone compounds.

[0009] According to an embodiment of the present invention, the accelerator is selected from alicyclic ketone compounds; illustratively, the accelerator is selected from saturated alicyclic ketone compounds or unsaturated alicyclic ketone compounds.

[0010] According to an embodiment of the present invention, the accelerator is selected from at least one of the compounds shown in Formula 1:

[0011]

[0012] Where R1 is C 1-5 Straight chain alkylene, C 2-5 A straight chain alkenylene group; R2 is -CH2- or -C(=O)-; R3 is C 1-5 Straight chain alkylene, C 2-5 A straight chain alkenylene group; R4 is a hydroxyl group, C 1-3 n is an integer between 0 and 6; the dotted line represents a single bond or a double bond.

[0013] According to an embodiment of the present invention, the C 1-5 The straight chain alkylene is, for example, -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH2CH2CH2CH2-; the C 2-5 The straight-chain alkenylene group is, for example, -CH=CH-, -CH=CH-CH2-, -CH=CH-CH2CH2-, -CH2-CH=CH-CH2-, -CH=CH-CH2CH2CH2-, -CH2-CH=CH-CH2-, -CH=CH-CH2CH2CH2-, -CH2-CH=CH-CH2CH2-; the C 1-3 The alkyl group is, for example, -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2; n is 0, 1, 2, 3, 4, 5 or 6.

[0014] According to an embodiment of the present invention, the accelerator is selected from one or more of cyclobutanone, cyclobutanedione (such as 1,2-cyclobutanedione), hydroxycyclobutanedione (such as 2-hydroxycyclobutanedione, 3-hydroxycyclobutanedione), cyclopentanone, cyclopentanedione (such as 1,3-cyclopentanedione), hydroxycyclopentanone (such as 2-hydroxycyclopentanone, 3-hydroxycyclopentanone), cyclohexanone, cyclohexanedione (such as 1,3-cyclohexanedione, 1,4-cyclohexanedione), hydroxycyclohexanone (such as 2-hydroxycyclohexanone, 3-hydroxycyclohexanone, 4-hydroxycyclohexanone), cycloheptanone, cycloheptanedione (such as 1,2-cycloheptanedione, 1,3-cycloheptanedione, 1,4-cycloheptanedione), etc., preferably at least one of cyclobutanone, cyclopentanone, cyclohexanone, cyclohexanedione, and 4-hydroxycyclohexanone.

[0015] In order to improve the single-pass conversion rate of cyclohexene in the process of preparing cyclohexanol by hydration of cyclohexene, the prior art generally introduces a phase transfer agent, a cosolvent or a solvent (such as benzoic acid, phenol, C 1-10 Alcohol, etc.), because these phase-transfer agents, cosolvents or solvents can increase the solubility of cyclohexene in water, so these phase-transfer agents, cosolvents or solvents can improve the per pass conversion of cyclohexene to a certain extent.But, these phase-transfer agents, cosolvents or solvents cause it to not enter the pore inside of solid acid catalyst due to reasons such as molecular size, and also can't reach the reactive site inside solid acid catalyst pore, therefore can't transfer the cyclohexanol generated near reactive site in solid acid catalyst pore.Therefore, even if phase-transfer agents, cosolvents or solvents are added in reaction system, the reaction selectivity of the cyclohexanol obtained is also very poor.Not only that, in order to increase the solubility of cyclohexene in water better, the amount of phase-transfer agents or solvents added in reaction system is higher, which can cause reaction to finish rear reaction product separation comparatively difficult, and also with the generation of a large amount of side reactions, greatly limits its application in industrialized production.

[0016] The inventor of the present application found through unexpected research that when the promoter of the present application is introduced into the reaction system of preparing cyclohexanol by hydration of cyclohexene, the promoter can promote the hydration reaction of cyclohexene and water under the action of a solid acid catalyst to generate cyclohexanol, which is mainly because the promoter of the present invention can enter the active site inside the pores of the solid acid catalyst, and the promoter of the present invention also has a hydrogen bonding force with cyclohexanol, so that the cyclohexanol generated by the reaction can be quickly transferred, breaking the limitation of the chemical equilibrium of the chemical reaction between cyclohexene and water, significantly improving the single-pass conversion rate of cyclohexene, the selectivity of cyclohexanol and the yield of cyclohexanol, and effectively improving the production capacity of cyclohexanol products. At the same time, the reaction has the characteristics of good selectivity, stability and safety, simple separation, recyclability, strong practicality, and considerable economic benefits, and can be widely used in the industrial production of cyclohexanol.

[0017] In the prior art, isophorone or 3,3,5-trimethylcyclohexanone is disclosed as a solvent or cosolvent in the reaction of preparing cyclohexanol by hydration of cyclohexene, but as mentioned above, the purpose of introducing these solvents or cosolvents in the reaction is to increase the solubility of cyclohexene in water, thereby increasing the probability of contact with the catalyst, but it cannot enter the pores of the solid acid catalyst, does not have the function and effect of transferring the cyclohexanol generated in the pores of the solid acid catalyst, and does not have selectivity, so it is impossible to achieve the improvement of cyclohexanol selectivity. The present invention unexpectedly found that when a ketone compound is used as a promoter in a composite catalyst, it has the function and effect of being able to enter the pores of the solid acid catalyst and transfer the cyclohexanol generated in the pores of the solid acid catalyst. The effect that the promoter of the present invention can achieve is completely different from the prior art. Further, the ketone compound of the present invention is preferably not isophorone or 3,3,5-trimethylcyclohexanone.

[0018] According to an embodiment of the present invention, the reactor is a conventional reaction vessel in the art for realizing cyclohexene hydration to prepare cyclohexanol. Exemplarily, the reactor may be an autoclave.

[0019] According to an embodiment of the present invention, the solid acid catalyst is selected from a molecular sieve type solid acid catalyst. Exemplarily, the solid acid catalyst is selected from at least one of a ZSM-5 molecular sieve catalyst, a ZSM-11 molecular sieve catalyst and a ZSM-5 / ZSM-11 eutectic molecular sieve catalyst.

[0020] According to an embodiment of the present invention, the particle size of the solid acid catalyst can be nanometer-level (such as 5-100 nm) or micrometer-level (such as 0.1-10 μm). That is, according to the particle size classification, the solid acid catalyst is selected from a nano solid acid catalyst or a micron solid acid catalyst.

[0021] According to an embodiment of the present invention, the pore size of the solid acid catalyst can be microporous (the main pore size is concentrated in the micropores) or porous (the main pore size is concentrated in the micropores and mesopores). That is, according to the pore size classification, the solid acid catalyst is selected from a microporous solid acid catalyst or a porous solid acid catalyst.

[0022] According to an embodiment of the present invention, the solid acid catalyst can be prepared by a method known in the art, or can be purchased through commercial channels.

[0023] According to an embodiment of the present invention, the molar ratio of water to cyclohexene is (0.8-10.0):1.0, for example, 0.8:1.0, 0.9:1.0, 1.0:1.0, 1.2:1.0, 1.5:1.0, 2.0:1.0, 2.5:1.0, 3.0:1.0, 3.5:1.0, 4.0:1.0, 4.5:1.0, 5.0:1.0, 5.5:1.0, 6.0:1.0, 6.5:1.0, 7.0:1.0, 7.5:1.0, 8.0:1.0, 8.5:1.0, 9.0:1.0, 9.5:1.0 or 10.0:1.0.

[0024] According to an embodiment of the present invention, the molar ratio of the promoter to cyclohexene is (0.05-2.0):1.0, for example, 0.05:1.0, 0.08:1.0, 0.1:1.0, 0.12:1.0, 0.15:1.0, 0.18:1.0, 0.2:1.0, 0.3:1.0, 0.4:1.0, 0.5:1.0, 0.6:1.0, 0.7:1.0, 0.8:1.0, 0.9:1.0, 1.0:1.0, 1.1:1.0, 1.2:1.0, 1.3:1.0, 1.4:1.0, 1.5:1.0, 1.6:1.0, 1.7:1.0, 1.8:1.0, 1.9:1.0 or 2.0:1.0.

[0025] According to an embodiment of the present invention, the mass ratio of the solid acid catalyst to cyclohexene is (0.1-2.0):1.0, for example, 0.1:1.0, 0.12:1.0, 0.15:1.0, 0.18:1.0, 0.2:1.0, 0.3:1.0, 0.4:1.0, 0.5:1.0, 0.6:1.0, 0.7:1.0, 0.8:1.0, 0.9:1.0, 1.0:1.0, 1.1:1.0, 1.2:1.0, 1.3:1.0, 1.4:1.0, 1.5:1.0, 1.6:1.0, 1.7:1.0, 1.8:1.0, 1.9:1.0 or 2.0:1.0.

[0026] According to an embodiment of the present invention, the hydration reaction is carried out under an inert atmosphere. Specifically, the inert atmosphere is, for example, nitrogen or argon.

[0027] According to an embodiment of the present invention, the temperature of the hydration reaction is 100°C-140°C, for example, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C or 140°C.

[0028] According to an embodiment of the present invention, the pressure of the hydration reaction is 0.1 MPa-1.0 MPa, for example, 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1.0 MPa.

[0029] According to an embodiment of the present invention, the hydration reaction time is 0.5h-4h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h.

[0030] Beneficial effects of the present invention:

[0031] The present invention provides a method for preparing cyclohexanol by hydration of cyclohexene. The present invention is that after a promoter is introduced into a reaction system for preparing cyclohexanol by hydration of cyclohexene, the promoter can promote the hydration reaction of cyclohexene and water under the action of a solid acid catalyst to generate cyclohexanol, break the limitation of the chemical equilibrium of the chemical reaction between cyclohexene and water, significantly improve the single-pass conversion rate of cyclohexene, the selectivity of cyclohexanol and the yield of cyclohexanol, and effectively improve the production capacity of cyclohexanol products. The method has the following advantages: the conversion rate of cyclohexene is high, the selectivity of cyclohexanol is good, the promoter used is stable and safe, does not react with substances in the reaction system, is easy to separate, can be recycled for multiple times, has strong practicality, and can be widely used in the industrial production of cyclohexanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a graph showing the reaction performance test results of Example 5. DETAILED DESCRIPTION

[0033] The method of the present invention will be described in further detail below in conjunction with specific examples. It should be understood that the following examples are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0034] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0035] The multi-level pore ZSM-5 molecular sieve catalyst used in the following examples and comparative examples has a pore size of micropore level and mesopore level; the nano ZSM-5 molecular sieve catalyst has a pore size of micropore level; the multi-level pore ZSM-11 molecular sieve catalyst has a pore size of micropore level and mesopore level.

[0036] Example 1

[0037] 50g of nano ZSM-5 molecular sieve catalyst, 30g of cyclopentanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 125°C under a nitrogen pressure of 0.5MPa under stirring. The reaction was stopped after 2h. The oil phase was sampled and analyzed by gas chromatography to calculate the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity. The results are shown in Table 1.

[0038] Example 2

[0039] 50g of nano ZSM-5 molecular sieve catalyst, 30g of cyclohexanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 100°C under a nitrogen pressure of 0.5MPa under stirring. The reaction was stopped after 2h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0040] Example 3

[0041] 50g of hierarchical ZSM-11 molecular sieve catalyst, 30g of cyclohexanedione, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 120°C under a nitrogen pressure of 0.5MPa under stirring. The reaction was stopped after 2h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0042] Example 4

[0043] 50g of nano ZSM-5 molecular sieve catalyst, 30g of cyclobutanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 130°C under a nitrogen pressure of 0.5MPa under stirring. The reaction was stopped after 2h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0044] Example 5

[0045] 50g of nano ZSM-5 molecular sieve catalyst, 35g of 4-hydroxycyclohexanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 140°C under a nitrogen pressure of 0.6MPa under stirring. The reaction was stopped after 3h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0046] Example 6

[0047] 50g of multi-level porous ZSM-5 molecular sieve catalyst, 20g of 4-hydroxycyclohexanone, 20g of cyclobutanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 125°C under a nitrogen pressure of 0.6MPa under stirring. The reaction was stopped after 3h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0048] Example 7

[0049] 50g of multi-level porous ZSM-5 molecular sieve catalyst, 40g of 4-hydroxycyclohexanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 130°C under a nitrogen pressure of 0.6MPa under stirring. The reaction was stopped after 3h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0050] Example 8

[0051] 25g of nano ZSM-5 molecular sieve catalyst, 25g of multi-level pore ZSM-5 molecular sieve catalyst, 40g of 4-hydroxycyclohexanone, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 140°C under a nitrogen pressure of 0.8MPa under stirring. The reaction was stopped after 3h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0052] Comparative Example 1

[0053] 50g of ZSM-5 molecular sieve catalyst, 50g of cyclohexene and 75g of water were placed in an autoclave and heated to 125°C under a nitrogen pressure of 0.5MPa while stirring. The reaction was stopped after 2h. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0054] Comparative Example 2

[0055] 30 g of cyclopentanone, 50 g of cyclohexene and 75 g of water were placed in an autoclave and heated to 125°C under a nitrogen pressure of 0.5 MPa while stirring. The reaction was stopped after 2 hours. The oil phase was sampled and analyzed by gas chromatography, and the cyclohexene conversion rate, cyclohexanol yield and cyclohexanol selectivity were calculated. The results are shown in Table 1.

[0056] Table 1 is the reaction performance test results of Examples 1-8 and Comparative Examples 1-2

[0057] Example Cyclohexene conversion rate (%) Cyclohexanol selectivity (%) Cyclohexanol yield (%) Example 1 28.2 100 28.2 Example 2 25.3 100 25.3 Example 3 24.8 99.9 24.8 Example 4 23.5 99.9 23.5 Example 5 30.3 100 30.3 Example 6 28.8 100 28.8 Example 7 29.7 100 29.7 Example 8 30.1 100 30.1 Comparative Example 1 10.0 98.2 9.8 Comparative Example 2 0 0 0

[0058] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing cyclohexanol by hydrating cyclohexene, the method comprising the steps of: Adding a solid acid catalyst, cyclohexene, a promoter and water into a reactor to carry out a hydration reaction to prepare the cyclohexanol; in, The accelerator is selected from ketone compounds.

2. The method according to claim 1, wherein: The accelerator is selected from alicyclic ketone compounds.

3. The method according to claim 2, wherein: The accelerator is selected from at least one of the compounds shown in Formula 1: Where R1 is C 1-5 Straight chain alkylene, C 2-5 A straight chain alkenylene group; R2 is -CH2- or -C(=O)-; R3 is C 1-5 Straight chain alkylene, C 2-5 A straight chain alkenylene group; R4 is a hydroxyl group, C 1-3 n is an integer between 0 and 6; the dotted line represents a single bond or a double bond.

4. The method according to claim 3, wherein: The accelerator is selected from one or more of cyclobutanone, cyclobutanedione, hydroxycyclobutanone, cyclopentanone, cyclopentanedione, hydroxycyclopentanone, cyclohexanone, cyclohexanedione, hydroxycyclohexanone, cycloheptanone and cycloheptanedione.

5. The method according to any one of claims 1 to 4, wherein: The solid acid catalyst is selected from molecular sieve type solid acid catalysts.

6. The method according to any one of claims 1 to 5, wherein: The solid acid catalyst is selected from at least one of a ZSM-5 molecular sieve catalyst, a ZSM-11 molecular sieve catalyst and a ZSM-5 / ZSM-11 eutectic molecular sieve catalyst.

7. The method according to any one of claims 1 to 6, wherein: The solid acid catalyst is selected from a nano solid acid catalyst or a micron solid acid catalyst; or, the solid acid catalyst is selected from a microporous solid acid catalyst or a porous solid acid catalyst.

8. The method according to any one of claims 1 to 7, wherein: The molar ratio of water to cyclohexene is (0.8-10.0):1.0; and / or, the molar ratio of the promoter to cyclohexene is (0.05-2.0):1.0; and / or, the mass ratio of the solid acid catalyst to cyclohexene is (0.1-2.0):1.

0.

9. The method according to any one of claims 1 to 8, wherein: The hydration reaction is carried out under an inert atmosphere, which is nitrogen or argon.

10. The method according to any one of claims 1 to 9, wherein: The temperature of the hydration reaction is 100° C.-140° C.; and / or, the pressure of the hydration reaction is 0.1 MPa-1.0 MPa; and / or, the time of the hydration reaction is 0.5 h-4 h.

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