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

Abstract

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

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of natural flavors, and relates to a preparation method of a catalytic oxidation catalyst based on rubber sludge and an application of the catalyst in catalytic oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system. BACKGROUND

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

[0003] Biomass-derived alcohols are an important class of platform compounds, and the stable price of derived alcohols has become a research hotspot in line with the sustainable development goals. The oxidative conversion of derived alcohols is one of the important ways to achieve sustainable production of bio-based chemicals. In recent years, the selective oxidation and 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, and is a very useful fixative. It is an indispensable spice in the blending of jasmine, yuehshao, ilan and other essences. However, benzyl alcohol will slowly and naturally oxidize, and part of it will generate benzaldehyde and anisole, which is not suitable for long-term storage, so strengthening the transformation and development and utilization of benzyl alcohol has broad space.

[0004] In addition, with the acceleration of urbanization and people's longing for a better living environment, rubber enterprises pay more and more attention to environmental problems. However, with the increasing discharge of wastewater from rubber enterprises and the improvement of wastewater treatment capacity, the amount of residual sludge generated during the wastewater treatment process has increased dramatically, and its output is huge. How to reasonably dispose and utilize the sludge has attracted more and more attention from the rubber industry and become an important problem that enterprises urgently need to solve, which is closely related to the sustainable development of China's rubber industry. Compared with other biomasses, 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 the critical transition metals (Fe, Mn, etc.) with various catalytic properties; and the main mineral components thereof 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 catalytic reactions, thereby avoiding the pollution of the environment caused by the subsequent separation and treatment of reaction liquids. SUMMARY

[0005] In view of the problems in the prior art, the application provides a preparation method of a rubber sludge-based catalytic oxidation catalyst and a method for preparing methyl benzoate by catalytically oxidizing and esterifying benzyl alcohol using the catalyst, the rubber sludge-based catalytic oxidation catalyst has the advantages of low cost, easy preparation, easy separation of catalytic reaction products, high product yield and low production cost, and has extremely high practical application value.

[0006] The rubber sludge discarded by a rubber factory is used as an alkali source, is simply mechanically ground and mixed with a cobalt salt and a nitrogen additive, is calcined to prepare a catalyst that can be applied to catalytic oxidation reaction, secondary pollution to the environment caused by municipal sludge conventional treatment methods such as landfill can be effectively avoided, problems such as low sludge calorific value and poor economic benefits faced by incineration can be solved, the alkali metal oxide component contained in the rubber sludge can be fully utilized to prepare a low-cost high-performance catalyst, the operation is simple and feasible, and the application conforms to the concept of green chemistry.

[0007] The preparation method of the rubber sludge-based catalytic oxidation catalyst is as follows:

[0008] 1. Rubber sludge from a sewage treatment stage of a rubber factory is naturally air-dried to a water content of 10%-12% under a ventilated environment, is ground and sieved to a particle size of less than 40 mesh to prepare rubber sludge powder;

[0009] 2. The rubber sludge powder, a nitrogen additive and a cobalt salt are mixed, are uniformly ground and mixed, and are calcined at 600-1000 DEG C for 2-4 h in an inert atmosphere to prepare a catalytic oxidation catalyst;

[0010] 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.

[0011] Another object of the application is to provide the catalyst prepared by the method.

[0012] Another object of the application is to apply the catalytic oxidation catalyst prepared by the method to catalytic oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system.

[0013] The benzyl alcohol and a solvent (methanol) are mixed, are placed in a high-pressure reaction kettle, the catalytic oxidation catalyst is added, and the mixture is reacted at 30-100 DEG C for 0.5-10 h in an oxygen atmosphere, the oxygen pressure is 0.1-5 MPa, and methyl benzoate is prepared;

[0014] The concentration of the benzyl alcohol in the solvent is 0.001-0.5 g / mL, and the mass ratio of the catalyst to the benzyl alcohol is (0.7-5.0) : 1.

[0015] The application has the following advantages and technical effects:

[0016] 1. The application provides a low-cost, solvent-free method for preparing a catalytic oxidation catalyst, which is simple, green, easy to mass-produce; the application can obtain the required catalyst through simple pretreatment, grinding and calcination, can effectively control the strength of the catalyst's acidity and alkalinity by changing the calcination temperature and time, fully utilizes the alkali metal oxides in rubber sludge to provide alkaline reaction conditions, does not need to add extra alkali in application, greatly reduces the harm to the environment caused by the subsequent separation and treatment of alkaline reaction liquid in the catalytic reaction, and is an economic, environmentally friendly and environmentally friendly catalyst preparation process.

[0017] 2. The catalytic oxidation catalyst prepared from rubber sludge can effectively oxidize benzyl alcohol in a methanol system to generate methyl benzoate.

[0018] In summary, the method effectively utilizes rubber sludge, realizes resource recycling, meets green environmental protection requirements, has low investment in the preparation process, can effectively avoid environmental pollution, has great industrialization value-added value; and the prepared catalytic oxidation catalyst has high catalytic efficiency, and can catalytically oxidize benzyl alcohol to prepare methyl benzoate under certain reaction conditions. DETAILED DESCRIPTION

[0019] The application will be further described in combination with examples, but the protection scope of the application is not limited to the content described, and the application is not limited in any way, and any transformation or replacement based on the teaching of the application belongs to the protection scope of the application.

[0020] The rubber sludge used in the following examples is derived from the main byproduct of the sewage stage of a rubber factory, and the main chemical components and contents of the rubber sludge are shown in Table 1.

[0021] Example 1

[0022] 1. The rubber sludge was placed in a ventilated environment and naturally dried to a moisture content of 10-12%, ground and passed through a 40-mesh steel sieve, and the undersize material was collected to obtain rubber sludge powder; 690 mg of rubber sludge powder was mixed with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate, and the mixture was ground and mixed uniformly, then placed in a tube furnace, heated to 600℃ at 5℃ / min under an argon atmosphere, and calcined for 2 hours to obtain a 600℃ calcined rubber sludge catalyst;

[0023] 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 uniformly, seal the reactor, purge with oxygen for 5 times to remove air and maintain 0.5 MPa oxygen pressure, then perform oxidative esterification at 80℃, 600 rpm / min for 4 h. After the reactor is cooled, qualitative and quantitative detection is performed using Agilent 7820 gas chromatograph, and the detection results are shown in Table 2, No. 1. Example 2

[0024] 1. Dry the rubber sludge in a ventilated environment to a moisture content of 10-12%, grind and pass through a 40-mesh steel sieve to collect the undersize, which is rubber sludge powder. Mix 690 mg of the rubber sludge powder with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate, grind and mix uniformly, and then place in a tube furnace. Under an argon atmosphere, heat to 700℃ at a rate of 5℃ / min and maintain for 2 h to obtain a 700℃-calcined rubber sludge catalyst;

[0025] 2. Use the catalyst prepared in step 1 to catalyze the oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system, the method being the same as in Example 1. After the reactor is cooled, qualitative and quantitative detection is performed using Agilent 7820 gas chromatograph, and the detection results are shown in Table 2, No. 2. Example 3

[0026] 1. Dry the rubber sludge in a ventilated environment to a moisture content of 10-12%, grind and pass through a 40-mesh steel sieve to collect the undersize, which is rubber sludge powder. Mix 690 mg of the rubber sludge powder with 248 mg of 1,10-phenanthroline and 125 mg of cobalt acetate, grind and mix uniformly, and then place in a tube furnace. Under an argon atmosphere, heat to 800℃ at a rate of 5℃ / min and maintain for 2 h to obtain an 800℃-calcined rubber sludge catalyst;

[0027] 2. Use the catalyst prepared in step 1 to catalyze the oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system, the method being the same as in Example 1. After the reactor is cooled, qualitative and quantitative detection is performed using Agilent 7820 gas chromatograph, and the detection results are shown in Table 2, No. 3. Example 4

[0028] 1. The preparation of the catalytic oxidation catalyst is the same as in Example 1, except that it is calcined at 900℃;

[0029] 2. Use the catalyst prepared in step 1 to catalyze the oxidation of benzyl alcohol to prepare methyl benzoate in an alkali-free system, the method being the same as in Example 1. After the reactor is cooled, qualitative and quantitative detection is performed using Agilent 7820 gas chromatograph, and the detection results are shown in Table 2, No. 4. Example 5

[0030] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except calcination at 1000°C;

[0031] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, in the same manner as in Example 1. After the reaction was completed and the reactor was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 5. Example 6

[0032] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except calcination at 600°C for 4h;

[0033] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, in the same manner as in Example 1. After the reaction was completed and the reactor was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 6. Example 7

[0034] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except calcination at 700°C for 4h;

[0035] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, in the same manner as in Example 1. After the reaction was completed and the reactor was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 7. Example 8

[0036] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except calcination at 800°C for 4h;

[0037] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, in the same manner as in Example 1. After the reaction was completed and the reactor was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 8. Example 9

[0038] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except calcination at 900°C for 4h;

[0039] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, in the same manner as in Example 1. After the reaction was completed and the reactor was cooled, qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 9.

[0040] Example 10:

[0041] 1. Preparation of the catalytic oxidation catalyst as in Example 1, except that calcination was carried out at 1000°C for 4h;

[0042] 2. The catalyst prepared in Step 1 was used to catalytically oxidize benzyl alcohol to methyl benzoate in an alkali-free system, as in Example 1. After the reaction was completed, the reactor was cooled, and qualitative and quantitative detection was performed using an Agilent 7820 gas chromatograph. The detection results are shown in Table 2, with serial number 10.

[0043] .

Claims

1. A method for preparing a rubber sludge catalytic oxidation catalyst, 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 under an inert atmosphere to prepare a catalytic oxidation catalyst; The nitrogen additive is 1,10-phenanthroline; the cobalt salt is cobalt acetate; The main mineral components of the rubber sludge are Fe2O330.7%, Al2O3 28.1%, CaO 6.8%, K2O 4.6%, and MgO 2.7%.

2. The method for preparing a rubber sludge catalytic oxidation catalyst 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.

3. The method for preparing a rubber sludge catalytic oxidation catalyst according to claim 1, wherein: Calcination is carried out at 600~1000℃ for 2~4 hours.

4. The catalytic oxidation catalyst prepared by the preparation method of the rubber sludge-based catalytic oxidation catalyst according to any one of claims 1 to 3.

5. Use of the catalytic oxidation catalyst according to claim 4 in the preparation of methyl benzoate by catalytic oxidation of benzyl alcohol in an alkali-free system.

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