Method for improving cyclohexene selectivity in selective hydrogenation reaction of benzene

Abstract

The invention relates to the technical field of petrochemical industry, and provides a method for improving cyclohexene selectivity in benzene selective hydrogenation reaction, which comprises the following steps: under the benzene selective hydrogenation condition, benzene and hydrogen are contacted with reaction slurry; the reaction slurry comprises a catalyst, water, zinc sulfate and an additive; the additive is selected from at least one of C2-C3 diol, glycerol, polyethylene glycol, ethanolamine, C2-C6 aliphatic amine and diphenylamine. The method can effectively improve the selectivity of the product cyclohexene.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a method for improving the selectivity of cyclohexene in a selective hydrogenation reaction of benzene. Background Art

[0002] Cyclohexene is an important organic synthesis intermediate, widely used in the production of medicine, food, feed, polyester materials and other fine chemical products. Cyclohexene can be directly hydrated to produce cyclohexanol, directly oxidized to produce adipic acid, or cyclohexanol can be dehydrogenated to produce cyclohexanone, and then produce caprolactam through a series of reactions. Adipic acid and caprolactam are the raw materials for preparing nylon-66 and nylon-6. The traditional route is to catalytically oxidize cyclohexane generated by selective hydrogenation of benzene to produce a mixture of cyclohexanol and cyclohexanone to prepare nylon-66 and nylon-6, which has the disadvantages of low single-pass yield, complex products, and by-products that cannot be reused. The new route of selective hydrogenation of benzene to produce cyclohexene shortens the production route of nylon-66 and caprolactam, has a high single-pass conversion rate, less by-products, is more energy-saving and environmentally friendly, and shows great industrial production potential.

[0003] Selective hydrogenation of benzene The target product of benzene hydrogenation reaction, cyclohexene, has a non-conjugated carbon-carbon double bond, which is more active than the conjugated double bond on the benzene ring and is more susceptible to hydrogenation reaction. In addition, from a thermodynamic point of view, the Gibbs free energy of benzene hydrogenation to cyclohexene becomes -23kJ / mol, while the free energy of benzene complete hydrogenation to cyclohexane becomes -98kJ / mol. The equilibrium of benzene hydrogenation reaction tends to produce cyclohexane, which is more thermodynamically stable. It is very difficult to achieve high selectivity of cyclohexene in the reaction process. For a long time before, the selectivity of cyclohexene was difficult to guarantee. Therefore, the selectivity of cyclohexene has always been one of the important indicators for evaluating catalyst performance.

[0004] The hydrogenation reaction of benzene is a gas-liquid reaction, and the existing device is carried out in an autoclave reactor. There are also many patents related to its reaction device, such as CN216296267U, CN112546970A, CN112552139A, CN202047018U, CN102139194A, CN101850225A, etc. After more than 30 years of research and development, many industrial reactors have been put into use for more than ten years. In recent years, the patents mainly involve the research and development of different catalyst preparation methods to improve the selectivity of cyclohexene, including CN110292925A, CN104028267A, CN102974342A, CN1978056A, CN 102600841A, etc. If a simple and easy new method can be proposed, the selectivity of the product cyclohexene can be effectively improved without changing the existing reactor, which will have good industrial application prospects. Summary of the invention

[0005] The purpose of the present invention is to improve the selectivity of cyclohexene in the selective hydrogenation reaction of benzene. The method for improving the selectivity of cyclohexene in the selective hydrogenation reaction of benzene provided by the present invention can effectively improve the selectivity of product cyclohexene.

[0006] In order to achieve the above object, the present invention provides a method for improving the selectivity of cyclohexene in the selective hydrogenation reaction of benzene, the method comprising the following steps:

[0007] contacting benzene and hydrogen with the reaction slurry under benzene selective hydrogenation conditions;

[0008] The reaction slurry comprises: a catalyst, water, zinc sulfate and additives;

[0009] The additive is selected from at least one of C2-C3 diols, glycerol, polyethylene glycol, ethanolamine, C2-C6 fatty amines and diphenylamine.

[0010] Through the above technical scheme, by adding the additive of the present invention to the reaction slurry, the selectivity of the product cyclohexene can be effectively improved; it is speculated that after adding the additive of the present invention, the hydrophilicity of the catalyst surface is improved, and the desorption of cyclohexene is promoted, thereby effectively improving the selectivity of the product cyclohexene. The method disclosed by the present invention is simple and effective, has a wide range of applicability, can achieve higher cyclohexene selectivity without changing the conditions of the existing reactor, and has good prospects for industrial promotion. DETAILED DESCRIPTION

[0011] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0012] The present invention provides a method for improving the selectivity of cyclohexene in a selective hydrogenation reaction of benzene, the method comprising the following steps:

[0013] contacting benzene and hydrogen with the reaction slurry under benzene selective hydrogenation conditions;

[0014] The reaction slurry comprises: a catalyst, water, zinc sulfate and additives;

[0015] The additive is selected from at least one of C2-C3 diols, glycerol, polyethylene glycol, ethanolamine, C2-C6 fatty amines and diphenylamine. The method of the present invention can effectively improve the selectivity of the product cyclohexene.

[0016] The benzene selective hydrogenation conditions refer to the conditions for the selective hydrogenation of benzene to produce cyclohexene.

[0017] In the present invention, the range of C2-C3 diols available for selection is relatively wide. According to a preferred embodiment of the present invention, the C2-C3 diol is selected from at least one of 1,3-propylene glycol and ethylene glycol.

[0018] According to a preferred embodiment of the present invention, the ethanolamine is selected from at least one of monoethanolamine and diethanolamine.

[0019] According to a preferred embodiment of the present invention, the C2-C6 fatty amine is selected from at least one of diethylamine, ethylenediamine and triethylamine.

[0020] According to a preferred embodiment of the present invention, the additive is selected from at least one of 1,3-propylene glycol, ethylene glycol, glycerol, polyethylene glycol, monoethanolamine, diethanolamine, diphenylamine, ethylenediamine, diethylamine and triethylamine.

[0021] According to a preferred embodiment of the present invention, the additive is selected from two or more of 1,3-propylene glycol, ethylene glycol, glycerol, polyethylene glycol, monoethanolamine, diethanolamine, diphenylamine, ethylenediamine, diethylamine and triethylamine; the above-mentioned additive composition is beneficial to further improve the selectivity of cyclohexene.

[0022] According to a preferred embodiment of the present invention, the additive is a mixture of polyethylene glycol, diphenylamine and ethylenediamine, and preferably the mass ratio of polyethylene glycol, diphenylamine and ethylenediamine is 1:0.5-6:0.3-10.

[0023] According to a preferred embodiment of the present invention, the additive is a mixture of diethylamine and diethanolamine, and preferably the mass ratio of diethylamine to diethanolamine is 1:0.2-15.

[0024] According to a preferred embodiment of the present invention, the additive is a mixture of 1,3-propylene glycol, ethylene glycol and monoethanolamine, preferably the mass ratio of 1,3-propylene glycol, ethylene glycol and monoethanolamine is 1:0.3-20:0.2-10. The use of the above additive composition is conducive to further improving the selectivity of cyclohexene.

[0025] In the present invention, the mass ratio of benzene to the reaction slurry can be selected in a wide range. According to a preferred embodiment of the present invention, the mass ratio of benzene to the reaction slurry is 0.1-10, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, preferably 0.1-2.

[0026] In the present invention, the mass ratio of the additive to the reaction slurry can be selected in a wide range. According to a preferred embodiment of the present invention, the mass ratio of the additive to water is 0.01%-10%, for example, it can be 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, preferably 0.01%-4%.

[0027] In the present invention, the mass ratio of the catalyst to the reaction slurry can be selected in a wide range. According to a preferred embodiment of the present invention, the mass ratio of the catalyst to water is 0.1%-10%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.7%, 3%, 3.2%, 3.3%, 3.5%, 3.6%, 3.8%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, preferably 0.4%-4%.

[0028] In the present invention, the mass ratio of zinc sulfate to the reaction slurry can be selected in a wide range. According to a preferred embodiment of the present invention, the mass percentage of zinc sulfate to water is 1%-40%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 30%, 35%, 40%, preferably 7%-20%.

[0029] In the present invention, the conventional hydrogenation conditions for preparing cyclohexene by selective hydrogenation of benzene in the art can be used in the present invention, and there is no particular limitation on the hydrogenation conditions. According to a preferred embodiment of the present invention, the hydrogenation conditions include: a temperature of 10-300°C, preferably 100-170°C; a rotation speed of 100-3000r / min, preferably 300-1200r / min.

[0030] In the present invention, the hydrogen pressure may be selected in a wide range. According to a preferred embodiment of the present invention, the hydrogen pressure is 0.5-10 MPa, preferably 4-6 MPa.

[0031] In the present invention, conventional catalysts for preparing cyclohexene by selective hydrogenation of benzene in the art can be used in the present invention, and there is no particular limitation on the catalyst. According to a preferred embodiment of the present invention, the catalyst is selected from Ru supported catalysts.

[0032] According to a preferred embodiment of the present invention, in the catalyst, the mass fraction of Ru is 0.5-30wt%, preferably 5-15wt%.

[0033] According to a preferred embodiment of the present invention, in the catalyst, the carrier is selected from at least one of ZrO2, SiO2 and Al2O3.

[0034] In the present invention, when the method is carried out in a reactor, a reaction slurry is first prepared, and a catalyst, water, zinc sulfate and an additive are prepared into a reaction slurry in proportion. After the preparation is completed, the reaction slurry is added to the reactor and a sealing cover is sealed. Nitrogen is introduced to replace the air in the reactor, and then benzene is introduced. After the device conditions (such as temperature and rotation speed) are stable, hydrogen is introduced, and the contact reaction is carried out by controlling the flow rate to maintain a stable pressure.

[0035] The present invention will be described in detail below through examples.

[0036] In the following examples, all samples were analyzed by gas chromatography (Agilent GC-8890) equipped with an HP-1 column, and the mass fraction of each component in the product was obtained by peak area correction normalization. The benzene conversion rate and the selectivity of cyclohexene were calculated by the following formula:

[0037]

[0038]

[0039] The catalysts are Ru-modified ZrO2 catalyst (the mass fraction of Ru is 10wt%), Ru-modified SiO2 catalyst (the mass fraction of Ru is 10wt%) and Ru-modified Al2O3 catalyst (the mass fraction of Ru is 10wt%).

[0040] Example 1

[0041] (1) A reaction slurry prepared by mixing 2.0 g of Ru-modified ZrO2 catalyst, 280 mL of water, 50 g of zinc sulfate and 8 g of an additive mixture (polyethylene glycol, diphenylamine and ethylenediamine in a mass ratio of 1:3:3) was added to a 1 L small autoclave, and then 140 mL of benzene was added. The sealing cover was sealed, and a certain amount of nitrogen was introduced to replace the air in the reactor. The magnetic stirrer was turned on and set to a speed of 600 r / min and a temperature of 150° C. After the temperature stabilized, hydrogen was introduced to maintain the pressure stable at 5.0 MPa. The obtained product had a cyclohexene selectivity of 82.4% when the benzene conversion rate was 51.2%.

[0042] Comparative Example 1

[0043] According to the method of Example 1, no additive mixture was added to the reaction slurry, and other conditions were the same as those of Example 1. The obtained product had a cyclohexene selectivity of 67.5% when the benzene conversion rate was 50.7%.

[0044] Example 2

[0045] After adding the reaction slurry prepared by 1.5g Ru modified SiO2 catalyst, 200mL water, 40g zinc sulfate and 6g additive mixture (diethylamine, diethanolamine mass ratio is 2:5) into a 1L small autoclave, 90mL benzene is added, the sealing cover is sealed, a certain amount of nitrogen is introduced to replace the air in the reactor, the magnetic stirrer is turned on and the speed is set to 500r / min and the temperature is 145°C. After the temperature is stable, hydrogen is introduced to keep the pressure stable at 4.8MPa; the product obtained has a cyclohexene selectivity of 70.5% when the benzene conversion rate is 49.8%.

[0046] Comparative Example 2

[0047] According to the method of Example 2, no additive was added to the reaction slurry, and other conditions were the same as those of Example 2. The obtained product had a cyclohexene selectivity of 59.4% when the benzene conversion rate was 51.2%.

[0048] Example 3

[0049] The reaction is carried out in a medium-sized high-pressure reactor; the reaction slurry contains Ru-modified Al2O3 catalyst, water and zinc sulfate, and an additive mixture (the mass ratio of 1,3-propylene glycol, ethylene glycol and monoethanolamine is 2:5:1) is added; the mass ratio of Ru-Zn / ZrO2 catalyst, zinc sulfate, water and additive mixture is 1:30:200:7.

[0050] The average benzene flow rate is 10.6 kg / h, the average slurry circulation volume is 33.4 kg / h, the benzene residence time is 20 min, the rotation speed is 200 r / min, the temperature is 140°C, and the hydrogen pressure is stable at 4.5 MPa; the obtained product has a cyclohexene selectivity of 77.5% when the benzene conversion rate is 52.1%.

[0051] Comparative Example 3

[0052] According to the method of Example 3, no additive mixture was added to the reaction slurry, and other conditions were the same as those of Example 3. The obtained product had a cyclohexene selectivity of 61.2% when the benzene conversion rate was 51.4%.

[0053] Example 4

[0054] The method of Example 2 was followed, except that the additive was 6 g of diethylamine, and the other conditions were the same as those of Example 2. The obtained product had a cyclohexene selectivity of 62.3% when the benzene conversion rate was 47.6%.

[0055] Example 5

[0056] The method of Example 2 was followed, except that the additive was 6 g of diethanolamine, and the other conditions were the same as those of Example 2. The obtained product had a cyclohexene selectivity of 65.2% when the benzene conversion rate was 48.6%.

[0057] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for improving the selectivity of cyclohexene in the selective hydrogenation reaction of benzene, characterized in that: The method comprises the following steps: contacting benzene and hydrogen with the reaction slurry under benzene selective hydrogenation conditions; The reaction slurry comprises: a catalyst, water, zinc sulfate and additives; The additive is selected from at least one of C2-C3 diols, glycerol, polyethylene glycol, ethanolamine, C2-C6 fatty amines and diphenylamine.

2. The method according to claim 1, wherein: The C2-C3 diol is selected from at least one of 1,3-propylene glycol and ethylene glycol; and / or The ethanolamine is selected from at least one of monoethanolamine and diethanolamine; and / or The C2-C6 fatty amine is selected from at least one of ethylenediamine, diethylamine and triethylamine.

3. The method according to claim 1 or 2, wherein: The additive is selected from at least one of 1,3-propylene glycol, ethylene glycol, glycerol, polyethylene glycol, monoethanolamine, diethanolamine, diphenylamine, ethylenediamine, diethylamine and triethylamine.

4. The method according to any one of claims 1 to 3, wherein: The additive is selected from two or more of 1,3-propylene glycol, ethylene glycol, glycerol, polyethylene glycol, monoethanolamine, diethanolamine, diphenylamine, ethylenediamine, diethylamine and triethylamine; Preferably, The additive is a mixture of polyethylene glycol, diphenylamine and ethylenediamine, and more preferably the mass ratio of polyethylene glycol, diphenylamine and ethylenediamine is 1:0.5-6:0.3-10; or The additive is a mixture of diethylamine and diethanolamine, and more preferably the mass ratio of diethylamine to diethanolamine is 1:0.2-15; or The additive is a mixture of 1,3-propylene glycol, ethylene glycol and ethanolamine, and more preferably the mass ratio of 1,3-propylene glycol, ethylene glycol and ethanolamine is 1:0.3-20:0.2-10.

5. The method according to any one of claims 1 to 4, wherein: The mass ratio of benzene to reaction slurry is 0.1-10, preferably 0.1-2.

6. The method according to any one of claims 1 to 5, wherein: The mass ratio of the additive to water is 0.01%-10%, preferably 0.01%-4%.

7. The method according to any one of claims 1 to 6, wherein: The mass ratio of catalyst to water is 0.1%-10%, preferably 0.4%-4%; and / or The mass percentage of zinc sulfate to water is 1%-40%, preferably 7%-20%.

8. The method according to any one of claims 1 to 7, wherein: Hydrogenation conditions include: temperature of 10-300°C, preferably 100-170°C; and / or The rotation speed is 100-3000r / min, preferably 300-1200r / min.

9. The method according to any one of claims 1 to 8, wherein: The hydrogen pressure is 0.5-10 MPa, preferably 4-6 MPa.

10. The method according to any one of claims 1 to 9, wherein: The catalyst is selected from Ru supported catalysts; Preferably, the mass fraction of Ru is 0.5-30wt%; and / or The carrier is selected from at least one of ZrO2, SiO2 and Al2O3.

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