Preparation method and application of catalytic oxidation catalyst based on rubber sludge

Abstract

The invention discloses a preparation method of a catalytic oxidation catalyst based on rubber sludge, which specifically comprises the following steps: naturally airing the rubber sludge until the water content is 10-12%, grinding and sieving, mixing the rubber sludge powder with a nitrogen additive and cobalt salt, grinding and uniformly mixing, and calcining to obtain the catalyst. The catalyst is used for preparing methyl benzoate through catalytic oxidation of benzyl alcohol in an alkali-free system, has the characteristics of high oxidation efficiency, low cost, easiness in obtaining, mild reaction conditions and the like, and has a very good industrial application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of natural fragrances, and relates to a method for preparing a catalytic oxidation catalyst based on rubber sludge and use of the catalyst in catalytically oxidizing benzyl alcohol to prepare methyl benzoate in an alkali-free system. Background Art

[0002] Fossil fuels are the most dependent resource for today's industry. Using mature petroleum refining processes, they can be converted into a variety of fuels, fine chemicals, pharmaceuticals, food additives and other petroleum-based materials to meet the needs of modern society. However, excessive dependence on non-renewable fossil fuel resources has led to a series of economic, social and environmental problems, including resource shortages and energy crises, large-scale emissions of environmental pollutants and global climate change.

[0003] Biomass-derived alcohols are an important class of platform compounds. The price stability of derived alcohols has become a research hotspot that meets the goal of sustainable development. The oxidation conversion of derived alcohols is one of the important ways to achieve sustainable production of bio-based chemicals. In recent years, the selective oxidation esterification products of biomass alcohols (such as furfuryl alcohol, benzyl alcohol, cinnamyl alcohol, etc.) have been widely used. Among these alcohols, benzyl alcohol, as one of the model compounds of biomass-derived alcohols, can be obtained from various natural biomass and organic resources. It is a very useful fixative and an indispensable fragrance for the formulation of jasmine, moonflower, ylang-ylang and other flavors. However, benzyl alcohol will slowly oxidize naturally, and part of it will produce benzaldehyde and anisole, which is not suitable for long-term storage. Therefore, there is a broad space for strengthening the transformation, development and utilization of benzyl alcohol.

[0004] In addition, with the acceleration of urbanization and people's yearning for a better living environment, rubber companies are paying more and more attention to environmental issues. However, with the increasing amount of wastewater discharged by rubber companies and the improvement of wastewater treatment capacity, the amount of residual sludge generated in the wastewater treatment process has increased dramatically, and its output is huge. How to reasonably dispose of and utilize sludge has attracted more and more attention from the rubber industry, and has become an important problem that companies need to solve urgently, which is closely related to the sustainable development of my country's rubber industry. Compared with other biomass, rubber sludge, as a carbon-rich biomass, has special catalytic and adsorption activity due to its complex composition and unique physical and chemical properties, especially critical transition metals (Fe, Mn, etc.) with various catalytic properties; and the main mineral components are alkaline metal oxides Fe2O3 (30.7%), Al2O3 (28.1%), CaO (6.8%), K2O (4.6%), and MgO (2.7%), which can provide an alkaline environment for the catalytic reaction, so that there is no need to add additional alkali sources, avoiding the pollution of the environment by the subsequent separation and treatment of the reaction liquid. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing a rubber sludge-based catalytic oxidation catalyst and a method for using the catalyst to catalyze the selective oxidative esterification of benzyl alcohol to prepare methyl benzoate. The rubber sludge-based catalytic oxidation catalyst of the present invention has the advantages of being cheap and easy to prepare, easy to separate the catalytic reaction products, high product yield, low production cost, etc., and has extremely high practical application value.

[0006] The present invention uses rubber sludge discarded by rubber factories as an alkali source, and through simple mechanical grinding and mixing with metal cobalt salt and nitrogen additives, calcination treatment is performed to prepare a catalyst that can be used for catalytic oxidation reaction. The present invention can effectively avoid the conventional treatment methods of municipal sludge, such as landfill causing secondary pollution to the environment, and incineration facing the problems of low sludge calorific value and poor economic benefits, and can fully utilize the alkaline metal oxide components contained in the rubber sludge to prepare a low-cost and high-performance catalyst. The operation is simple and feasible, and it conforms to the concept of green chemistry.

[0007] The preparation method of the rubber sludge catalytic oxidation catalyst of the present invention is as follows: 1. Dry the rubber sludge from the wastewater treatment stage of the rubber factory naturally in a ventilated environment until the moisture content is 10%-12%, grind it and sieve it to a particle size of less than 40 meshes to obtain rubber sludge powder; 2. Mix rubber sludge powder, nitrogen additive and cobalt salt, grind and mix well, and then calcine at 600-1000°C for 2-4 h in an inert atmosphere to obtain a catalytic oxidation catalyst; The mass ratio of the rubber sludge powder to the nitrogen additive is (2-3): 1, the mass ratio of the rubber sludge powder to the cobalt salt is (5-6): 1, the nitrogen additive is 1,10-phenanthroline; and the cobalt salt is cobalt acetate.

[0008] Another object of the present invention is to provide a catalyst prepared by the above method.

[0009] Another object of the present invention is to use the catalytic oxidation catalyst prepared by the above method in the catalytic oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system.

[0010] The benzyl alcohol and the solvent (methanol) are mixed and placed in a high-pressure reactor, a catalytic oxidation catalyst is added, and the mixture is reacted at 30-100°C in an oxygen atmosphere for 0.5-10 h, and the oxygen pressure is 0.1-5 MPa to obtain methyl benzoate; The concentration of benzyl alcohol in the solvent is 0.001-0.5 g / mL, and the mass ratio of the catalyst to benzyl alcohol is (0.7-5.0):1.

[0011] Advantages and technical effects of the present invention: 1. The present invention provides a low-cost, solvent-free method for preparing a catalytic oxidation catalyst, and the preparation process is simple, green and environmentally friendly, and easy to prepare on a large scale; the present invention can obtain the desired catalyst through simple pretreatment, grinding, and calcination, and the acidity and alkalinity of the catalyst can be effectively regulated by changing the calcination temperature and time, and the alkali metal oxides in the rubber sludge are fully utilized to provide alkaline reaction conditions. No additional alkali is required in the application, which greatly reduces the harm to the environment caused by the subsequent separation and treatment of the alkaline reaction liquid in the catalytic reaction, and is an economical, environmentally friendly and environmentally friendly catalyst preparation process; 2. The catalytic oxidation catalyst prepared from rubber sludge in the present invention can effectively oxidize benzyl alcohol to generate methyl benzoate in a methanol system; In summary, the method of the present invention effectively utilizes rubber sludge, realizes resource recycling, meets green environmental protection requirements, has low investment in the preparation process, can effectively avoid environmental pollution, and has great industrial added value; and the prepared catalytic oxidation catalyst has high catalytic efficiency, and catalytically oxidizes benzyl alcohol to prepare methyl benzoate under certain reaction conditions. DETAILED DESCRIPTION

[0012] The present invention is further described in detail below in conjunction with embodiments, but the protection scope of the present invention is not limited to the described contents, and the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0013] The rubber sludge used in the following examples is derived from the main by-product of the wastewater stage of a rubber factory. The main chemical components and contents of the rubber sludge are shown in Table 1.

[0014] Example 1

[0015] 1. Place the rubber sludge in a ventilated environment and dry it naturally until the moisture content is 10-12%. Grind it and pass it through a 40-mesh steel sieve. Collect the sieve-under material to obtain rubber sludge powder. Mix 690 mg of rubber sludge powder with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate. Grind and mix well. Place in a tube furnace. In an argon atmosphere, heat it to 600°C at a rate of 5°C / min and calcine it for 2 hours to obtain a rubber sludge catalyst calcined at 600°C for 2 hours. 2. Add 0.5 mmol (0.054 g) of benzyl alcohol and 5 mL of methanol into a 25 mL high-pressure reactor, then add 0.04 g of the catalyst prepared in step 1, mix well, seal the reactor, purge the air with oxygen 5 times and maintain an oxygen pressure of 0.5 MPa, then carry out oxidative esterification at 80 ° C and 600 rpm / min for 4 h. After the reaction is completed, the reactor is cooled and qualitative and quantitative detection is carried out using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 1. Example 2

[0016] 1. Place the rubber sludge in a ventilated environment and dry it naturally until the moisture content is 10-12%. Grind it and pass it through a 40-mesh steel sieve. Collect the sieve-under material to obtain rubber sludge powder. Mix 690 mg of rubber sludge powder with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate. Grind and mix well. Place in a tube furnace. In an argon atmosphere, heat to 700°C at a rate of 5°C / min and calcine for 2 hours to obtain a rubber sludge catalyst calcined at 700°C for 2 hours. 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, with serial number 2. Example 3

[0017] 1. Place the rubber sludge in a ventilated environment and dry it naturally until the moisture content is 10-12%. Grind it and pass it through a 40-mesh steel sieve. Collect the sieve-under material to obtain rubber sludge powder. Mix 690 mg of rubber sludge powder with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate. Grind and mix well. Place in a tube furnace. In an argon atmosphere, heat it to 800°C at a rate of 5°C / min and calcine it for 2 hours to obtain a rubber sludge catalyst calcined at 800°C for 2 hours. 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 3. Example 4

[0018] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 900°C; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, with serial number 4. Example 5

[0019] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 1000°C; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 5. Example 6

[0020] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that the catalyst is calcined at 600° C. for 4 h; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 6. Example 7

[0021] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 700° C. for 4 h; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate, and the method was the same as that in Example 1. After the reaction kettle was cooled, the qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 7. Example 8

[0022] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 800° C. for 4 h; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 8. Example 9

[0023] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 900° C. for 4 h; 2. The catalyst prepared in step 1 was used to catalyze the oxidation of benzyl alcohol in an alkali-free system to prepare methyl benzoate. The method was the same as that in Example 1. After the reaction kettle was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 9.

[0024] Embodiment 10: 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that the catalyst is calcined at 1000° C. for 4 h; 2. Using the catalyst prepared in step 1 to catalytically oxidize benzyl alcohol in an alkali-free system to prepare methyl benzoate, the method is the same as that in Example 1. After the reaction is completed and the reactor is cooled, qualitative and quantitative detection is performed using an Agilent 7820 gas chromatograph. The test results are shown in Table 2, serial number 10; .

Claims

1. A method for preparing a catalyst for catalytic oxidation based on rubber sludge, characterized in that: The rubber sludge is naturally dried to a moisture content of 10%-12%, and after grinding and screening, the rubber sludge powder is mixed with a nitrogen additive and a cobalt salt, ground and mixed, and then calcined to obtain a catalytic oxidation catalyst.

2. The method for preparing a catalyst based on rubber sludge catalytic oxidation according to claim 1, characterized in that: The nitrogen additive is 1,10-phenanthroline; and the cobalt salt is cobalt acetate.

3. The method for preparing a catalyst based on rubber sludge catalytic oxidation according to claim 1, characterized in that: The mass ratio of rubber sludge powder to nitrogen additive is (2~3):1, and the mass ratio of rubber sludge powder to cobalt salt is (5~6):

1.

4. The method for preparing a catalyst based on rubber sludge catalytic oxidation according to claim 1, characterized in that: Calcination is carried out in an inert atmosphere at 600~1000℃ for 2~4 hours.

5. The catalytic oxidation catalyst obtained by the preparation method of the rubber sludge-based catalytic oxidation catalyst according to any one of claims 1 to 4.

6. Use of the catalytic oxidation catalyst according to claim 5 in catalytic oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system.

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