Preparation method and application of catalyst for preparing cyclohexene through selective hydrogenation of benzene

Abstract

The invention provides a preparation method and application of a catalyst for preparing cyclohexene through selective hydrogenation of benzene, and mainly solves the problems that the catalyst is inconvenient to recover, the cyclohexene selectivity is low, the corrosion rate of instruments and equipment is high, and the like, the preparation method specifically comprises the following steps: hydrolyzing a silicon source and a titanium source in an acidic aqueous solution to obtain a titanium-silicon composite carrier; ruthenium trichloride is loaded on the titanium-silicon composite carrier through an impregnation method; and finally, the catalyst and a cocatalyst zinc salt are mixed, kneaded, molded, dried and roasted according to the mass ratio of 1: (1-10) to obtain the integral benzene hydrogenation catalyst. The reaction conditions of the catalyst in the benzene selective hydrogenation reaction are as follows: the temperature is 100-200 DEG C, the hydrogen pressure is 3-6 MPa, and the volume ratio of benzene to water is 1: (1-10).

Description

Technical Field

[0001] The invention belongs to the field of catalytic chemistry, and in particular relates to a preparation method and application of a catalyst for selective hydrogenation of benzene to cyclohexene. Background Art

[0002] In the field of organic chemistry, the selective hydrogenation of benzene is an important reaction that can convert benzene into cyclohexene with higher economic value. Cyclohexene is a very important chemical raw material. Because of its structure with an active C=C double bond and two active α-H, it is widely used in the production of high-value chemical products such as cyclohexanol, adipic acid, caprolactam, nylon 6, nylon 66, etc. The route of preparing cyclohexene by selective hydrogenation of benzene has the advantages of simple and safe reaction process, high atomic utilization rate, only by-product cyclohexane, and low environmental pollution. However, the price of ruthenium metal is high and the loading is high, resulting in high catalyst cost, and too high loading may cause the stability of the catalyst to decrease, thereby affecting the long-term operation of the reaction. Therefore, how to reduce the loading of ruthenium metal while ensuring the stability and selectivity of the catalyst is an important problem facing current technology. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation method and application of a catalyst for selective hydrogenation of benzene to cyclohexene. An organic base is used in the synthesis of a titanium-silicon composite carrier to facilitate subsequent treatment and avoid the introduction of heteroatoms. The catalyst and a co-catalyst are kneaded and mixed into an integral catalyst for easy recycling. In order to achieve the above invention purpose, the technical solution adopted by the present invention is: A catalyst system for selective hydrogenation of benzene to cyclohexene comprises the following steps: a silicon source and a titanium source are hydrolyzed in an aqueous solution of trimesic acid to obtain a titanium-silicon composite carrier; ruthenium trichloride is loaded onto the titanium-silicon composite carrier by an impregnation method; and finally the catalyst and a co-catalyst zinc salt are kneaded, formed, dried and calcined in a mass ratio of 1:1-10 to obtain an integral benzene hydrogenation catalyst.

[0004] The specific implementation steps are as follows: prepare a titanium-silicon composite carrier, add a silicon source and a titanium source in a molar ratio of 1:1-5 to a trimesic acid aqueous solution with a pH of 2-5 for hydrolysis, aging, filtering, drying, and calcining to obtain a titanium-silicon composite carrier.

[0005] The aging time is 8-12 hours, the aging temperature is 60-90°C, the drying time is 10-12 hours, the drying temperature is 80-100°C, the roasting time is 4-5 hours, and the roasting temperature is 400-500°C.

[0006] Prepare the catalyst precursor and stir and disperse the carrier in 0.01-0.05 mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 0.5-2h, adding 0.005-0.05 mol / L-1 The RuCl3 aqueous solution was stirred at room temperature for 3-5 hours, filtered until there was no chloride ion, and dried at 60-80°C overnight to obtain a catalyst precursor.

[0007] To prepare an integral benzene hydrogenation catalyst, a catalyst precursor and a co-catalyst zinc salt are kneaded in a molar ratio of 1:1-10, and then heated and reduced to obtain an integral benzene hydrogenation catalyst. The heating temperature is 140-300°C, the reducing gas is H2 / Ar=5-20%, and the reduction is 1-4h.

[0008] The prepared catalyst is added into a reactor, and then used for the selective hydrogenation reaction of benzene.

[0009] The catalyst and water are added into the reactor in a certain proportion, hydrogen is introduced, and when the temperature is raised to a certain temperature, benzene is added through the feed port to start the reaction, cyclohexene is prepared, and sampling is performed for analysis.

[0010] In the reaction process, the volume ratio of benzene to water is 0.1-5, the hydrogen pressure is 3-5Mpa, the temperature is 130-150°C, and the stirring is performed at 600-1200r / min for 10-120min.

[0011] The catalyst is applied to the reaction of preparing cyclohexene by selective hydrogenation of benzene, and the conversion rate of benzene is higher than 60% or more, more preferably higher than 70%, and further preferably higher than 80%.

[0012] The selectivity of the main product cyclohexene is higher than 50%, more preferably higher than 60%, and further preferably higher than 70%.

[0013] The yield is higher than 45%, more preferably higher than 55%. Compared with the prior art, the present invention reduces the loading amount of ruthenium metal under the condition of ensuring high conversion rate and high selectivity, greatly reduces the catalyst cost, and after the catalyst is circulated 20 times, the catalyst yield of cyclohexene is still higher than 45%, and has excellent cyclic use stability. The catalyst preparation process is simple, the cost is low, and it is suitable for industrial production. DETAILED DESCRIPTION

[0014] Example 1 Weigh 10g of methyl orthosilicate (0.05mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=3 trimesic acid aqueous solution at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:1. Stir and disperse 2g of carrier in 10mL 0.01mol / L -1Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 5g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in a 10% hydrogen / argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-1; The BJQ-1 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 20 minutes, the benzene conversion rate of the catalyst was 81.84%, the cyclohexene selectivity was 66.06%, and the cyclohexene yield was 54.06%.

[0015] Example 2 Weigh 2g of methyl orthosilicate (0.01mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=3 trimesic acid aqueous solution at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:5; Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 5g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in 10% hydrogen-argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-2; The BJQ-2 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 20 minutes, the benzene conversion rate of the catalyst was 76.36%, the cyclohexene selectivity was 74.51%, and the cyclohexene yield was 56.89%.

[0016] Example 3 Weigh 10g of methyl orthosilicate (0.05mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=3 trimesic acid aqueous solution at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:1. Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 10g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in 10% hydrogen-argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-3; The BJQ-3 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 20 minutes, the benzene conversion rate of the catalyst was 78.74%, the cyclohexene selectivity was 73.44%, and the cyclohexene yield was 57.83%.

[0017] Example 4 Weigh 2g of methyl orthosilicate (0.01mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=3 trimesic acid aqueous solution at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:5; Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 10g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in 10% hydrogen-argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-4; The BJQ-4 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 30 minutes, the benzene conversion rate of the catalyst was 80.05%, the cyclohexene selectivity was 68.22%, and the cyclohexene yield was 54.61%.

[0018] Example 5 Weigh 10g of methyl orthosilicate (0.05mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=2 aqueous solution of trimesic acid at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:1. Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 5g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in a 10% hydrogen / argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-5; The BJQ-5 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 30 minutes, the benzene conversion rate of the catalyst was 83.84%, the cyclohexene selectivity was 56.06%, and the cyclohexene yield was 47.00%.

[0019] Example 6 Weigh 10g of methyl orthosilicate (0.05mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=4 trimesic acid aqueous solution at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:1. Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of catalyst precursor and 5g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80℃ for 12h, calcine at 500℃ for 5h, and reduce at 300℃ for 2h in a 10% hydrogen / argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-6; The BJQ-6 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 20 minutes, the benzene conversion rate of the catalyst was 78.32%, the cyclohexene selectivity was 65.06%, and the cyclohexene yield was 50.95%.

[0020] Example 7 Weigh 10g of methyl orthosilicate (0.05mol) and 17g of tetrabutyl titanate (0.05mol) and slowly add them dropwise to 3L of pH=5 aqueous solution of trimesic acid at 40°C for hydrolysis. After the addition is completed, stir at 40°C for 1h, age at 80°C for 10h, filter, dry at 100°C for 12h, and calcine at 400°C for 4h to obtain a titanium-silicon composite carrier with Ti:Si=1:1. Stir and disperse 2g of carrier in 10mL 0.01mol / L -1 Ultrasonication in potassium carbonate aqueous solution for 1 h, add 10 mL 0.04 mol / L -1 The RuCl3 aqueous solution was stirred at room temperature for 3 h, filtered until there was no chloride ion, and dried at 80°C for 12 hours to obtain a catalyst precursor with a Ru mass percentage of 1%; Weigh 1g of the catalyst precursor and 5g of anhydrous zinc sulfate into an agate mortar, grind evenly, dry at 80°C for 12h, calcine at 500°C for 5h, and reduce at 300°C for 2h in a 10% hydrogen / argon mixed gas to obtain the monolithic benzene hydrogenation catalyst BJQ-7; The BJQ-7 catalyst prepared above was applied to the experiment of selective hydrogenation of benzene to prepare cyclohexene. 1g of catalyst and 100 mL of deionized water were placed in a high-pressure reactor, and 50 mL of benzene was placed in a feed tank. After nitrogen replacement for 5 times, 5MPa H2 was charged, and the reaction was heated to 150 °C at 1000 r / min. The valve of the feed tank was opened, benzene was added to the reactor, and the timing reaction was started. At 20 minutes, the benzene conversion rate of the catalyst was 63.84%, the cyclohexene selectivity was 59.13%, and the cyclohexene yield was 41.05%.

[0021] The above examples illustrate the present invention, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be equivalent replacement methods. As long as they meet the purpose of the invention, they belong to the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene, characterized in that: The steps include: Step 1, preparing a titanium-silicon composite carrier, adding a silicon source and a titanium source dropwise into a trimesic acid aqueous solution for hydrolysis, aging, filtering, drying, and calcining to obtain a titanium-silicon composite carrier; Step 2, preparing a catalyst precursor, stirring and dispersing the titanium silicon composite support in a potassium carbonate aqueous solution, ultrasonically uniformly, adding a RuCl3 aqueous solution, stirring at room temperature for 3-5 hours, washing, filtering until there is no chloride ion, and drying overnight to obtain a catalyst precursor; Step 3, preparing an integral benzene hydrogenation catalyst, kneading the catalyst precursor and the co-catalyst zinc salt into a mixture, and reducing them under heating conditions to obtain a benzene selective hydrogenation catalyst to cyclohexene.

2. The method for preparing a catalyst for preparing cyclohexene by selective hydrogenation of benzene according to claim 1, characterized in that: In step 1, the silicon source includes any one of methyl orthosilicate, ethyl orthosilicate, and water glass.

3. The method for preparing the catalyst for preparing cyclohexene by selective hydrogenation of benzene according to claim 1, characterized in that: In step 1, the titanium source is any one of tetrabutyl titanate, tetraisopropyl titanate, and titanium tetrachloride.

4. The method for preparing the catalyst for preparing cyclohexene by selective hydrogenation of benzene according to claim 1, characterized in that: In step 1, the pH of the trimesic acid aqueous solution is 2-5.

5. The method for preparing the catalyst for preparing cyclohexene by selective hydrogenation of benzene according to claim 1, characterized in that: In step 1, the aging time is 8-12 hours, the aging temperature is 60-90°C, the drying time is 10-12 hours, the drying temperature is 80-100°C, the roasting time is 4-5 hours, and the roasting temperature is 400-500°C.

6. The method for preparing the catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The concentration of potassium carbonate aqueous solution is 0.01-0.05 mol / L -1 , the mass concentration of RuCl3 aqueous solution is 0.005-0.05 mol / L -1 .

7. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: The catalyst precursor and the promoter zinc salt have a molar ratio of 1:1-10; the zinc salt is any one of zinc sulfate, zinc nitrate and zinc chloride.

8. The method for preparing a catalyst for selective hydrogenation of benzene to cyclohexene according to claim 1, characterized in that: In step 3, the heating temperature is 140-300°C, the reducing gas is H2 / Ar=5-20%, and the reduction time is 1-4h.

9. A method for preparing cyclohexene by selective hydrogenation of benzene using the catalyst according to any one of claims 1 to 8, characterized in that: Catalyst and water are added into a reaction kettle at a ratio of 1:1-10, hydrogen is introduced, and when the temperature is raised to a certain temperature, benzene is added through the feed port to start the reaction, thereby preparing cyclohexene.

10. The method for preparing cyclohexene by selective hydrogenation of benzene using the catalyst according to claim 9, characterized in that: In the reaction process, the volume ratio of benzene to water is 0.1-5, the hydrogen pressure is 3-5Mpa, the temperature is 130-150°C, and the stirring is performed at 600-1200r / min for 10-120min.