Method for preparing cyclohexene oxide

Abstract

The invention discloses a method for preparing cyclohexene oxide, which comprises the following steps: taking a titanium silicalite molecular sieve Ti-MWW of which the surface is loaded with a covalent organic framework material LZU-1 as a catalyst, recording as LZU-1 (at) Ti-MWW, and catalyzing cyclohexene epoxidation reaction to generate cyclohexene oxide in the presence of a solvent and an oxidizing agent. The covalent organic framework material is modified outside the inorganic material titanium silicalite molecular sieve to obtain the composite molecular sieve catalyst, the composite molecular sieve catalyst has good catalyst activity in a reaction for preparing cyclohexene oxide through cyclohexene epoxidation, and the reaction conversion rate is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and specifically relates to a method for preparing cyclohexene oxide by catalyzing the reaction of cyclohexene and hydrogen peroxide using a composite molecular sieve as a catalyst. Background Art

[0002] Epoxides are an important class of intermediates in the fields of petrochemicals, fine chemicals and pharmaceutical synthesis. Cyclohexene oxide is an important class of epoxy compounds. Its epoxy group is quite active and can be converted into a series of other widely used compounds by selective ring opening. It is used in the production of pesticides, plasticizers, and synthesis of degradable material monomers, etc., and has a good market prospect. The traditional process uses the method of recycling light oil waste liquid to obtain cyclohexene oxide, but because its output is limited by the output of the main products cyclohexanone and cyclohexanol, and the purity of the product is low, it seriously restricts the development of cyclohexene oxide. Therefore, the production of cyclohexene oxide by organic synthesis is the main source of cyclohexene oxide at home and abroad.

[0003] With the maturity of the process of preparing cyclohexene by unsaturated hydrogenation of benzene, the process of preparing cyclohexene oxide by epoxidation reaction using cyclohexene as raw material has attracted wide attention from researchers. According to the different oxidants used, there are roughly the following preparation routes for synthesizing cyclohexene oxide at home and abroad: organic peroxyacid method, which often uses peroxyformic acid or acetic acid as oxidants, and peroxyacids are unstable and easy to decompose; hypochlorous acid oxidation method, Japanese patents first reported the method of adding cyclohexene to HOCl and then condensing it into a ring. The use of this method will produce a large amount of wastewater, and it needs to be treated with strong alkali, which pollutes the environment; molecular oxygen oxidation method, which requires the use of aldehydes as co-oxidants, and the route is relatively clean and environmentally friendly, but the yield is low and the separation is complicated; hydrogen peroxide oxidation method, which is low in price, environmentally friendly, and the oxidation product is non-toxic, harmless, and pollution-free water, which is in line with the development trend of green chemistry today, but the use of hydrogen peroxide as an oxidant usually requires the addition of high-efficiency catalysts during the reaction to enhance its activity.

[0004] The hydrogen peroxide oxidation method is in line with the development trend of green chemistry today. If an efficient catalyst can be developed, it will have a good application prospect. According to current reports, the new catalytic oxidation system composed of titanium silicon molecular sieve and hydrogen peroxide overcomes the problems of harsh conditions and environmental pollution in traditional processes, and has good catalytic activity in the synthesis of propylene oxide. However, when it is applied to the cyclohexene epoxidation system, there are some shortcomings such as low cyclohexene conversion rate and low target product yield. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for preparing cyclohexene oxide. The present invention modifies a covalent organic framework material on the outside of an inorganic material titanium silicon molecular sieve to obtain a composite molecular sieve catalyst, which has good catalyst activity in the reaction of preparing cyclohexene oxide by epoxidation of cyclohexene, and greatly improves the reaction conversion rate.

[0006] The method for preparing cyclohexene oxide of the present invention comprises the following contents: using a titanium silicon molecular sieve Ti-MWW with a surface-loaded covalent organic framework material LZU-1 as a catalyst, denoted as LZU-1@Ti-MWW, to catalyze the epoxidation reaction of cyclohexene to generate cyclohexene oxide in the presence of a solvent and an oxidant.

[0007] In the method of the present invention, the catalyst is based on weight, LZU-1 is 0.8% to 9.0%, and Ti-MWW is 91.0% to 99.2%. In the method of the present invention, the preparation method of the catalyst LZU-1@Ti-MWW includes the following contents: titanium silicon molecular sieve Ti-MWW, iso-tritylaldehyde, p-phenylenediamine, and ethanol are uniformly mixed, then acetic acid aqueous solution is added, hydrothermally crystallized, and then washed and dried to obtain the catalyst.

[0008] The mass ratio of the titanium silicon molecular sieve Ti-MWW, isophthalic acid, p-phenylenediamine and ethanol is 1:0.05-0.3:0.05-0.3:5-15.

[0009] The concentration of the acetic acid aqueous solution is 1 mol / L to 6 mol / L, and the added amount is 0.1 to 0.5 mL.

[0010] The hydrothermal crystallization treatment is generally carried out in a high-pressure reactor at a temperature of 100 to 150° C. for 2 to 5 days.

[0011] The washing process is a conventional suction filtration washing process in the field of molecular sieves, such as washing with anhydrous ethanol for 2 to 5 times until the filtrate is colorless.

[0012] The drying conditions are as follows: drying temperature is 60-100° C. and drying time is 4-6 hours.

[0013] In the method of the present invention, the oxidant is one or more of hydrogen peroxide solution and tert-butyl hydroperoxide solution, the mass concentration of the oxidant is 30% to 70%, and the dosage is 0.2 to 2.0 g H2O2 / g cyclohexene, preferably 1.0 to 1.5 g H2O2 / g cyclohexene.

[0014] In the method of the present invention, the solvent is one or more of methanol, acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide, preferably acetonitrile.

[0015] In the method of the present invention, the cyclohexene epoxidation reaction conditions are: reaction temperature 50-90° C., reaction time 2-6 hours.

[0016] In the method of the present invention, the dosage of LZU-1@Ti-MWW is 0.05-0.75 g / g cyclohexene, and the dosage of the catalyst is preferably 0.1-0.3 g / g cyclohexene.

[0017] Compared with the prior art, the present invention has achieved the following beneficial effects: the present invention adopts the method of depositing covalent organic framework materials on the surface of titanium silicon molecular sieve to prepare a novel organic-inorganic composite catalytic material LZU-1@Ti-MWW, the surface polarity of the titanium silicon molecular sieve can be regulated by controlling the amount of organic monomer added, and the preparation method is simple and easy to operate; the composite catalyst is used in the reaction process of preparing cyclohexene oxide under mild conditions, and the catalytic activity is improved compared with the titanium silicon molecular sieve not deposited on the surface, and a higher raw material conversion rate is obtained at a lower reaction temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope photo of titanium silicate molecular sieve Ti-MWW.

[0019] Figure 2 This is a scanning electron microscope photograph of the catalyst LZU-1@Ti-MWW of Example 1. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0021] Example 1

[0022] 16 mg of triphenylaldehyde, 16 mg of p-phenylenediamine, 0.2 g of Ti-MWW and 2 mL of ethanol were placed in a 10 mL pressure tube, fully shaken and ultrasonicated, and then 0.2 mL of 3 mol / L acetic acid aqueous solution was added. The air above the solution was replaced with nitrogen and then placed in an oven at 120 ° C for 3 days. The obtained solid powder was filtered, washed three times with anhydrous ethanol, dried at 100 ° C for 6 hours, and calcined at 200 ° C for 4 hours to obtain the LZU-1@Ti-MWW-1 catalyst.

[0023] Example 2

[0024] 32 mg of triphenylaldehyde, 32 mg of p-phenylenediamine, 0.2 g of Ti-MWW and 2 mL of ethanol were placed in a 10 mL pressure tube, fully shaken and ultrasonicated, and then 0.2 mL of 3 mol / L acetic acid aqueous solution was added. The air above the solution was replaced with nitrogen and then placed in an oven at 120 ° C for 3 days. The obtained solid powder was filtered, washed three times with anhydrous ethanol, dried at 100 ° C for 6 hours, and calcined at 200 ° C for 4 hours to obtain the LZU-1@Ti-MWW-2 catalyst.

[0025] Example 3

[0026] 48 mg of triphenylaldehyde, 48 mg of p-phenylenediamine, 0.2 g of Ti-MWW and 2 mL of ethanol were placed in a 10 mL pressure tube, fully shaken and ultrasonicated, and then 0.2 mL of 3 mol / L acetic acid aqueous solution was added. The air above the solution was replaced with nitrogen and then placed in an oven at 120°C for 3 days. The obtained solid powder was filtered, washed three times with anhydrous ethanol, dried at 100°C for 6 hours, and calcined at 200°C for 4 hours to obtain the LZU-1@Ti-MWW-3 catalyst.

[0027] The methods of Examples 1-3 were used to synthesize catalyst materials with different COF deposition amounts on the surface. The COF deposition amount of the LZU-1@Ti-MWW-1 catalyst was 1.5wt%, the COF deposition amount of the LZU-1@Ti-MWW-3 catalyst was 4.3wt%, and the COF deposition amount of the LZU-1@Ti-MWW-2 was 2.9wt%.

[0028] Example 4 The catalytic epoxidation performance of LZU-1@Ti-MWW-1, LZU-1@Ti-MWW-2 and LZU-1@Ti-MWW-3 was evaluated. The specific process was as follows: 10 mL of acetonitrile solvent, 3.2 g of reactant cyclohexene, 4.5 g of a 30.0% hydrogen peroxide solution were added in sequence in a 50 mL flask, and finally 0.6 g of the composite catalyst was added. Under stirring, the reaction temperature was set to 65 ° C and the reaction time was 5 h. After the reaction was completed, the conversion rate, selectivity and yield were analyzed by gas chromatography.

[0029] The catalytic performance results are summarized in Table 1. It can be seen from the table that the catalyst LZU-1@Ti-MWW-1 has higher catalytic activity and epoxide yield.

[0030] Table 1 Catalyst performance test results of Example 4

[0031] catalyst Cyclohexene conversion rate / % Cyclohexene oxide selectivity / % LZU-1@Ti-MWW-1 96.1 94.3 LZU-1@Ti-MWW-2 92.1 85.2 LZU-1@Ti-MWW-3 65.7 79.1

[0032] Example 5

[0033] In a 50 mL flask, 10 mL acetonitrile solvent, 3.2 g cyclohexene, 3.6 g 30.0% hydrogen peroxide solution were added in sequence, and finally 0.6 g LZU-1@Ti-MWW-1 composite catalyst was added. Under stirring, the reaction temperature was set to 50 ° C and the reaction time was 5 h. After the reaction was completed, gas chromatography analysis showed that the cyclohexene conversion rate was 53.5% and the selectivity was 68.0%.

[0034] Example 6

[0035] In a 50mL flask, 10mL of methanol solvent, 3.2g of cyclohexene, 1.6g of 70.0% tert-butyl hydroperoxide solution were added in sequence, and finally 0.6g of LZU-1@Ti-MWW-1 composite catalyst was added. Under stirring, the reaction temperature was set to 80°C and the reaction time was 5h. After the reaction was completed, gas chromatography analysis showed that the cyclohexene conversion rate was 85.1% and the selectivity was 82.3%.

[0036] Example 7

[0037] In a 50 mL flask, 10 mL acetonitrile solvent, 3.2 g cyclohexene, 4.5 g 50.0% hydrogen peroxide solution were added in sequence, and finally 1.2 g LZU-1@Ti-MWW-1 composite catalyst was added. Under stirring, the reaction temperature was set to 90 ° C and the reaction time was 2 h. After the reaction was completed, gas chromatography analysis showed that the cyclohexene conversion rate was 98.3% and the selectivity was 92.1%.

[0038] Comparative Example 1

[0039] In a 50 mL flask, 10 mL acetonitrile solvent, 3.2 g cyclohexene, 4.5 g 30.0% hydrogen peroxide solution were added in sequence, and finally 0.6 g Ti-MWW catalyst was added. Under stirring, the reaction temperature was set to 80 ° C and the reaction time was 5 h. After the reaction was completed, gas chromatography analysis showed that the cyclohexene conversion rate was 64.0% and the cyclohexene oxide selectivity was 71.5%.

[0040] Comparative Example 2

[0041] In a 50 mL flask, 10 mL acetonitrile solvent, 3.2 g cyclohexene, 3.6 g 30.0% hydrogen peroxide solution were added in sequence, and finally 0.6 g Ti-MWW catalyst was added. Under stirring, the reaction temperature was set to 50 ° C and the reaction time was 5 h. After the reaction was completed, gas chromatography analysis showed that the cyclohexene conversion rate was 27.6% and the cyclohexene oxide selectivity was 63.1%.

[0042] By comparing LZU-1@Ti-MWW and Ti-MWW, it can be seen that the composite catalyst disclosed in the present invention has a higher catalytic activity, and using it in the process of producing cyclohexene oxide by oxidation of cyclohexene can improve the raw material conversion rate and the target product selectivity.

Claims

1. A method for preparing cyclohexene oxide, characterized in that The invention includes the following contents: a titanium silicalite Ti-MWW with a surface-loaded covalent organic framework material LZU-1 is used as a catalyst, denoted as LZU-1@Ti-MWW, to catalyze the epoxidation reaction of cyclohexene to produce cyclohexene oxide in the presence of a solvent and an oxidant.

2. The method according to claim 1, characterized in that: The catalyst is based on weight, LZU-1 is 0.8% to 9.0%, and Ti-MWW is 91.0% to 99.2%.

3. The method according to claim 1, characterized in that: The preparation method of the catalyst LZU-1@Ti-MWW comprises the following contents: uniformly mixing titanium silicon molecular sieve Ti-MWW, iso-tritylaldehyde, p-phenylenediamine and ethanol, adding acetic acid aqueous solution, hydrothermally crystallizing, washing and drying to obtain the catalyst.

4. The method according to claim 3, characterized in that: The mass ratio of the titanium silicon molecular sieve Ti-MWW, mesityleneformaldehyde, p-phenylenediamine and ethanol is 1:0.05-0.3:0.05-0.3:5-15.

5. The method according to claim 3, characterized in that: The concentration of the acetic acid aqueous solution is 1 mol / L~6 mol / L, and the added amount is 0.1~0.5 mL.

6. The method according to claim 3, characterized in that: The hydrothermal crystallization treatment is generally carried out in a high-pressure reactor, the hydrothermal crystallization conditions are 100-150° C., and the reaction lasts 2-5 days.

7. The method according to claim 3, characterized in that: The drying conditions are as follows: drying temperature is 60-100° C. and drying time is 4-6 hours.

8. The method according to claim 1, characterized in that: The oxidant is one or more of hydrogen peroxide solution and tert-butyl hydroperoxide solution, the mass concentration of the oxidant is 30% to 70%, and the dosage is 0.2 to 2.0 g H2O2 / g cyclohexene, preferably 1.0 to 1.5 g H2O2 / g cyclohexene.

9. The method according to claim 1, characterized in that: The solvent is one or more of methanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, preferably acetonitrile.

10. The method according to claim 1, characterized in that: The cyclohexene epoxidation reaction conditions are: reaction temperature 50-90° C., reaction time 2-6 hours.

11. The method according to claim 1, characterized in that: The dosage of LZU-1@Ti-MWW is 0.05-0.75 g / g cyclohexene, and the preferred dosage of the catalyst is 0.1-0.3 g / g cyclohexene.

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