An alumina-based catalyst and its application in the epoxidation reaction of olefins

Abstract

The present invention discloses an alumina-based catalyst, and its preparation method includes: (1) preparing an aluminum oxide matrix; (2) preparing a primary coated product; (3) preparing an iridium oxide-loaded product; (4) treating the iridium oxide-loaded product with an ethanol solution of γ-aminopropyltriethoxysilane and copper Meso-tetra(4-carboxyphenyl)porphyrin to obtain the alumina-based catalyst. The catalyst prepared by the method of the present invention has a good catalytic effect on the epoxidation reaction of olefins, greatly improves the conversion rate of olefins, makes the reaction more complete, and has a relatively high selectivity for the target product alkylene oxide and relatively few reaction by-products.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to an alumina-based catalyst and its application in the epoxidation reaction of olefins. Background Art

[0002] The epoxidation reaction is a very important type of oxidation reaction. The epoxide product contains an active three-membered oxygen ring structure, which is prone to ring-opening reactions under various conditions and can react with various functional groups such as amines and alcohols to produce fine chemical products and intermediates with high added value. It is a type of widely used and extremely important chemical raw material, which is widely used in various chemical production fields such as organic synthesis and fine chemicals. For example, ethylene oxide is mainly used to manufacture important chemical raw materials such as ethylene glycol, and can be used to synthesize chemical products such as detergents, surfactants, antifreeze agents, and emulsifiers; propylene oxide is mainly used to produce chemical raw materials such as polyether polyols and propylene glycol, and can also be used to synthesize various fine chemical products such as unsaturated resins and nonionic surfactants.

[0003] Generally, catalysts are required for the epoxidation reaction of olefins. For example, in the current production process of ethylene oxide, ethylene is used as the raw material and silver is used as the catalyst. However, in many cases, the current catalysts have poor catalytic effects in epoxidation, resulting in more by-products and incomplete reactions, causing a large amount of material waste. Summary of the Invention

[0004] Therefore, the present invention provides an alumina-based catalyst, and its preparation method includes the following steps:

[0005] (1) Prepare an ethanol solution of aluminum sec-butoxide, keep the ethanol solution of aluminum sec-butoxide in a water bath at a constant temperature of 60±2°C, and carry out condensation reflux during the constant temperature process; stir the ethanol solution of aluminum sec-butoxide, add deionized water to the ethanol solution of aluminum sec-butoxide under stirring, continue to stir for more than 100 min after the addition is completed, then carry out solid-liquid separation, dry the solid phase at 70°C for more than 20 h, and then calcine it at a temperature of 550-560°C for 6-7 h. After the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix;

[0006] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. Keep the dispersion in a water bath at a constant temperature of 80 ± 3 °C for heat preservation. Stir the dispersion under the heat preservation state. Add silica sol to the dispersion under the stirring state. After the feeding is completed, continue to keep the dispersion at 80 ± 3 °C for heat preservation and stirring for more than 50 min. Then add N,N-diisopropylethylamine to the dispersion under the stirring state. After the feeding is completed, continue to keep the dispersion at 80 ± 3 °C for heat preservation and stirring for more than 30 min. Then let it stand in the air for more than 20 h. After standing, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for more than 60 h. Then air-cool it to room temperature, perform solid-liquid separation. Wash the solid phase with deionized water for more than 3 times, dry it at 100 °C for more than 1 h. Then place it in a muffle furnace at 500 - 530 °C for calcination for 3 - 4 h, and air-cool it to room temperature to obtain a primary coated product;

[0007] (3) Prepare an ethanol solution of chloroiridic acid. Immerse the primary coated product in the ethanol solution of chloroiridic acid for 1 min. Then perform solid-liquid separation. Dry the solid phase at 100 - 110 °C for more than 10 min. Then place it in a muffle furnace at 450 °C for calcination for more than 15 min. After calcination, air-cool it to room temperature. Immerse it in the ethanol solution of chloroiridic acid again for 1 min. After immersion, perform solid-liquid separation. Dry the solid phase again at 100 - 110 °C for more than 10 min. Then place it in a muffle furnace at 450 °C for calcination for more than 15 min. After calcination, air-cool it to room temperature. One set of the above-mentioned immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is a combined process. Repeat the above combined process for more than 8 groups. Finally, calcine it in a muffle furnace at 450 °C for more than 1 h. Then air-cool it to room temperature to obtain an iridium oxide-loaded product;

[0008] (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. Keep the mixed solution in a water bath at a constant temperature of 60 ± 3 °C for heat preservation and stirring for more than 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. After the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection. Then heat it to 180 ± 2 °C for heat preservation and magnetic stirring for more than 20 h. Then air-cool it to room temperature. Open the reaction kettle, perform solid-liquid separation. Wash the solid phase with ethanol and dry it to obtain the alumina-based catalyst.

[0009] Further, in the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 10 - 20 g / 100 mL, and the solvent is ethanol; the volume ratio of adding deionized water to the ethanol solution of aluminum sec-butoxide is ethanol solution of aluminum sec-butoxide:deionized water = 1:1 - 2.

[0010] Further, in the step (2), the mass ratio of solid to liquid for dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30; the mass ratio of the added silica sol and N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.6 - 1.4:0.4 - 0.5:1.

[0011] Further, in the step (3), the mass percentage of chloroiridic acid in the ethanol solution of chloroiridic acid is 5% - 6%, and the solvent is ethanol; the mass ratio of solid to liquid for soaking the primary coating product in the ethanol solution of chloroiridic acid is solid / liquid = 1:30.

[0012] Further, in the step (4), in the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 4% - 6%, and the solvent is ethanol; the mass ratio of solid to liquid for soaking the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid

[0013] = 1:20; the mass ratio of added copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.2 - 1.7:1.

[0014] The present invention also discloses the application of the above-mentioned alumina-based catalyst in the epoxidation reaction of olefins. Olefins, the alumina-based catalyst, an alkyl peroxide, and a reaction solvent are mixed for reaction. The reaction temperature is 30 - 70 °C, and the reaction time is 7 - 8 h.

[0015] Further, the alkyl peroxide is any one of tert-butyl hydroperoxide and cumene hydroperoxide; the reaction solvent is one of acetonitrile, cyclohexane, or tert-butanol; the olefin is a C3 - C8 linear olefin or cycloolefin.

[0016] Further, the mass ratio of the mixture of olefins, the alumina-based catalyst, the alkyl peroxide, and the reaction solvent is olefins:alumina-based catalyst:alkyl peroxide:reaction solvent = 15 - 20:1 - 3:6 - 8:100.

[0017] The mechanism of the technical solution of the present invention is as follows: First, a silicon-aluminum layer is formed on the surface of the nano-alumina structure. By utilizing the excellent adsorption and ion exchange properties of the silicon-aluminum layer, the reactants of the olefin epoxidation reaction are more likely to be adsorbed on the catalyst surface, promoting the reaction to proceed rapidly and improving the catalytic efficiency. Then, by utilizing the high catalytic activity and good ion transport ability of the iridium oxide and the ligand compound attached to the surface, the catalytic activity of the catalyst is further improved, thereby improving the selectivity of the target product.

[0018] The beneficial effects of the present invention are as follows: The catalyst prepared by the method of the present invention has good catalytic effect on the epoxidation reaction of olefins, greatly improving the conversion rate of olefins, making the reaction more complete, and having a relatively high selectivity for the target product alkylene oxide and relatively few reaction by-products. Detailed implementation manners

[0019] The present invention will be further described below in conjunction with embodiments.

[0020] Example 1

[0021] An alumina-based catalyst, and its preparation method includes the following steps:

[0022] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 10 g / 100 mL, and the solvent is ethanol; keep the ethanol solution of aluminum sec-butoxide in a water bath at a constant temperature of 60 ± 2 °C, and carry out condensation reflux during the constant temperature process; stir the ethanol solution of aluminum sec-butoxide at 50 r / min, and add deionized water to the ethanol solution of aluminum sec-butoxide under stirring. The volume ratio of the added deionized water to the ethanol solution of aluminum sec-butoxide is ethanol solution of aluminum sec-butoxide: deionized water = 1:1; continue stirring for 100 min after the feeding is completed, then carry out solid-liquid separation, dry the solid phase at 70 °C for 20 h, then calcine it at 550 °C for 6 h, and cool it to room temperature in air after the calcination is completed to obtain the aluminum oxide matrix;

[0023] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion liquid. The solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30; keep the dispersion liquid in a water bath at a constant temperature of 80 ± 3 °C for heat preservation, stir the dispersion liquid at 50 r / min under the heat preservation state, add silica sol to the dispersion liquid under stirring, and continue to keep the dispersion liquid at 80 ± 3 °C for heat preservation and stirring for 50 min after the feeding is completed. Then add N,N-diisopropylethylamine to the dispersion liquid under stirring. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion liquid is silica sol: N,N-diisopropylethylamine: aluminum oxide matrix = 0.6:0.4:1; continue to keep the dispersion liquid at 80 ± 3 °C for heat preservation and stirring for 30 min after the feeding is completed, then let it stand in air for 20 h. After the standing is completed, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then cool it to room temperature in air, open the reaction kettle, carry out solid-liquid separation, wash the solid phase with deionized water 3 times, dry it at 100 °C for 1 h, then calcine it in a muffle furnace at 500 °C for 4 h, and cool it to room temperature in air to obtain the primary coating product;

[0024] (3) Prepare an ethanol solution of iridium(III) chloride hydrate. The mass percentage of iridium(III) chloride hydrate in the ethanol solution of iridium(III) chloride hydrate is 5%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of iridium(III) chloride hydrate for 1 min. The solid-liquid mass ratio of the primary coated product immersed in the ethanol solution of iridium(III) chloride hydrate is solid / liquid = 1:30. Then, perform solid-liquid separation, dry the solid phase at 100 °C for 10 min, then place it in a muffle furnace at 450 °C and calcine for 15 min. After calcination, air-cool to room temperature, immerse it in the ethanol solution of iridium(III) chloride hydrate again for 1 min. After immersion, perform solid-liquid separation, dry the solid phase at 100 °C for 10 min again, then place it in a muffle furnace at 450 °C and calcine for 15 min. After calcination, air-cool to room temperature. One set of the above immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is an overall combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine in a muffle furnace at 450 °C for 1 h, and then air-cool to room temperature to obtain an iridium oxide-loaded product;

[0025] (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 4%, and the solvent is ethanol. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.2:1. After adding the materials, seal the reaction kettle, fill it with nitrogen for protection, then heat to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, and then air-cool to room temperature. Open the reaction kettle, perform solid-liquid separation, wash the solid phase with ethanol, and dry it to obtain the alumina-based catalyst.

[0026] Example 2

[0027] An alumina-based catalyst, and its preparation method includes the following steps:

[0028] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 13 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and perform condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. While stirring, add deionized water to the ethanol solution of aluminum sec-butoxide. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water added is ethanol solution of aluminum sec-butoxide:deionized water = 1:1. After the addition is completed, continue stirring for 100 min, then perform solid-liquid separation. The solid phase is dried at 70 °C for 20 h, then calcined at 550 °C for 6 h. After the calcination is completed, air-cool to room temperature to obtain the aluminum oxide matrix.

[0029] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of the aluminum oxide matrix dispersed in deionized water is solid / liquid = 1:30. Keep the dispersion at a constant temperature of 80 ± 3 °C in a water bath for heat preservation. While in the heat preservation state, stir the dispersion at 50 r / min. While stirring, add silica sol to the dispersion. After the addition is completed, continue to keep the dispersion at 80 ± 3 °C for heat preservation and stir for 50 min. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the silica sol, N,N-diisopropylethylamine added to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.8:0.4:1. After the addition is completed, continue to keep the temperature at 80 ± 3 °C for heat preservation and stir for 30 min. Then, let it stand in the air for 20 h. After the standing is completed, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool to room temperature, open the reaction kettle, perform solid-liquid separation. The solid phase is washed 3 times with deionized water, dried at 100 °C for 1 h, then calcined in a muffle furnace at 500 °C for 4 h, and air-cooled to room temperature to obtain the primary coated product.

[0030] (3) Prepare an ethanol solution of chloroiridic acid. In the ethanol solution of chloroiridic acid, the mass percentage of chloroiridic acid is 5%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of chloroiridic acid for 1 min. The solid-liquid mass ratio of the primary coated product immersed in the ethanol solution of chloroiridic acid is solid / liquid = 1:30. Then perform solid-liquid separation. The solid phase is dried at 100 °C for 10 min, then calcined in a muffle furnace at 450 °C for 15 min. After the calcination, air-cool to room temperature, and then immerse it in the ethanol solution of chloroiridic acid again for 1 min. After the immersion, perform solid-liquid separation. The solid phase is dried again at 100 °C for 10 min, then calcined in a muffle furnace at 450 °C for 15 min. After the calcination, air-cool to room temperature. One set of the above immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is a combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine in a muffle furnace at 450 °C for 1 h, and then air-cool to room temperature to obtain the iridium oxide-loaded product.

[0031] (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 5%, and the solvent is ethanol. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.5:1. After the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, then air-cool it to room temperature, open the reaction kettle, separate the solid and liquid, wash the solid with ethanol, and dry it to obtain the alumina-based catalyst.

[0032] Example 3

[0033] An alumina-based catalyst, and its preparation method includes the following steps:

[0034] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 18 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and carry out condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. Under the stirring state, add deionized water to the ethanol solution of aluminum sec-butoxide. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water added is ethanol solution of aluminum sec-butoxide:deionized water = 1:2. After the feeding is completed, continue to stir for 100 min, then separate the solid and liquid, dry the solid at 70 °C for 20 h, then calcine it at 560 °C for 6 h, and after the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix.

[0035] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30. Keep the dispersion in a water bath at a constant temperature of 80 ± 3 °C for heat preservation. Stir the dispersion at 50 r / min under the heat preservation state. While stirring, add silica sol to the dispersion. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 50 min at 80 ± 3 °C. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 1.2:0.5:1. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 30 min at 80 ± 3 °C. Then, let it stand in the air for 20 h. After the standing is completed, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool it to room temperature. Open the reaction kettle, perform solid-liquid separation. Wash the solid phase with deionized water 3 times, dry it at 100 °C for 1 h, then place it in a muffle furnace at 530 °C for calcination for 3 h, and air-cool it to room temperature to obtain a primary coated product;

[0036] (3) Prepare an ethanol solution of iridium chloride. The mass percentage of iridium chloride in the ethanol solution of iridium chloride is 6%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of iridium chloride for 1 min. The solid-liquid mass ratio of immersing the primary coated product in the ethanol solution of iridium chloride is solid / liquid = 1:30. Then perform solid-liquid separation. Dry the solid phase at 100 °C for 10 min, and then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. Immerse it again in the ethanol solution of iridium chloride for 1 min. After immersion, perform solid-liquid separation. Dry the solid phase again at 100 °C for 10 min, and then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. One set of the above-mentioned immersion, solid-liquid separation, drying, calcination and air-cooling process steps is a combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine it in a muffle furnace at 450 °C for 1 h, and then air-cool it to room temperature to obtain an iridium oxide-loaded product;

[0037] (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 5%, and the solvent is ethanol. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.5:1. After the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, then air-cool it to room temperature, open the reaction kettle, separate the solid and liquid, wash the solid with ethanol, and dry it to obtain the alumina-based catalyst.

[0038] Example 4

[0039] An alumina-based catalyst, and its preparation method includes the following steps:

[0040] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 15 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and carry out condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. Add deionized water to the ethanol solution of aluminum sec-butoxide under stirring. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water is ethanol solution of aluminum sec-butoxide:deionized water = 1:2. After the feeding is completed, continue stirring for 100 min, then separate the solid and liquid, dry the solid at 70 °C for 20 h, then calcine it at 560 °C for 6 h, and after the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix.

[0041] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30. Keep the dispersion in a water bath at a constant temperature of 80 ± 3 °C for heat preservation. Stir the dispersion at 50 r / min under the heat preservation state. While stirring, add silica sol to the dispersion. After the feeding is completed, continue to keep the dispersion at 80 ± 3 °C for heat preservation and stirring for 50 min. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 1.4:0.5:1. After the feeding is completed, continue to keep the temperature at 80 ± 3 °C for heat preservation and stirring for 30 min. Then, let it stand in the air for 20 h. After standing, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool it to room temperature. Open the reaction kettle, perform solid-liquid separation. Wash the solid phase with deionized water 3 times, dry it at 100 °C for 1 h, then place it in a muffle furnace at 530 °C for calcination for 3 h, and air-cool it to room temperature to obtain a primary coated product;

[0042] (3) Prepare an ethanol solution of iridium chloride. The mass percentage of iridium chloride in the ethanol solution of iridium chloride is 6%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of iridium chloride for 1 min. The solid-liquid mass ratio of immersing the primary coated product in the ethanol solution of iridium chloride is solid / liquid = 1:30. Then perform solid-liquid separation. Dry the solid phase at 100 °C for 10 min, then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. Immerse it again in the ethanol solution of iridium chloride for 1 min. After immersion, perform solid-liquid separation. Dry the solid phase again at 100 °C for 10 min, then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. One set of the above immersion, solid-liquid separation, drying, calcination and air-cooling process steps is an overall combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine it in a muffle furnace at 450 °C for 1 h, and then air-cool it to room temperature to obtain an iridium oxide-loaded product;

[0043] (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 6%, and the solvent is ethanol. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.7:1. After the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, then air-cool it to room temperature, open the reaction kettle, separate the solid and liquid, wash the solid with ethanol, and dry it to obtain the alumina-based catalyst.

[0044] Comparative Example 1

[0045] An alumina-based catalyst, and its preparation method includes the following steps:

[0046] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 13 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and perform condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. Add deionized water to the ethanol solution of aluminum sec-butoxide under stirring. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water is ethanol solution of aluminum sec-butoxide:deionized water = 1:1. After the feeding is completed, continue stirring for 100 min, then separate the solid and liquid, dry the solid at 70 °C for 20 h, then calcine it at 550 °C for 6 h, and after the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix.

[0047] (2) Prepare an ethanol solution of iridium chlorate. The mass percentage of iridium chlorate in the ethanol solution of iridium chlorate is 5%, and the solvent is ethanol. Immerse the aluminum oxide substrate in the ethanol solution of iridium chlorate for 1 min. The solid-liquid mass ratio of the aluminum oxide substrate immersed in the ethanol solution of iridium chlorate is solid / liquid = 1:30. Then, perform solid-liquid separation. The solid phase is dried at 100 °C for 10 min, then placed in a muffle furnace at 450 °C and calcined for 15 min. After calcination, it is air-cooled to room temperature, and then immersed in the ethanol solution of iridium chlorate again for 1 min. After immersion, perform solid-liquid separation. The solid phase is dried again at 100 °C for 10 min, then placed in a muffle furnace at 450 °C and calcined for 15 min. After calcination, it is air-cooled to room temperature. One set of the above-mentioned immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is an overall combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine in a muffle furnace at 450 °C for 1 h, and then air-cool to room temperature to obtain an iridium oxide-loaded product;

[0048] (3) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 5%, and the solvent is ethanol. Immerse the iridium oxide-loaded product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper Meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper Meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper Meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide-loaded product = 1.5:1. After adding the materials, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, and then air-cool to room temperature. Open the reaction kettle, perform solid-liquid separation, wash the solid phase with ethanol, and dry it to obtain the alumina-based catalyst of this comparative example.

[0049] Comparative Example 2

[0050] An alumina-based catalyst, and its preparation method includes the following steps:

[0051] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 13 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and carry out condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. While stirring, add deionized water to the ethanol solution of aluminum sec-butoxide. The volume ratio of the added deionized water to the ethanol solution of aluminum sec-butoxide is ethanol solution of aluminum sec-butoxide:deionized water = 1:1. After the addition is completed, continue stirring for 100 min, then carry out solid-liquid separation. The solid phase is dried at 70 °C for 20 h, then calcined at 550 °C for 6 h. After the calcination is completed, air-cool to room temperature to obtain the aluminum oxide matrix;

[0052] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of the aluminum oxide matrix dispersed in deionized water is solid / liquid = 1:30. Keep the dispersion at a constant temperature of 80 ± 3 °C in a water bath for heat preservation. Stir the dispersion at 50 r / min under the heat preservation state. While stirring, add silica sol to the dispersion. After the addition is completed, continue to keep the dispersion at 80 ± 3 °C for heat preservation and stir for 50 min. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.8:0.4:1. After the addition is completed, continue to keep the temperature at 80 ± 3 °C for heat preservation and stir for 30 min. Then, let it stand in the air for 20 h. After the standing is completed, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool to room temperature, open the reaction kettle, carry out solid-liquid separation. The solid phase is washed 3 times with deionized water, dried at 100 °C for 1 h, then calcined in a muffle furnace at 500 °C for 4 h, and air-cooled to room temperature to obtain the primary coated product;

[0053] (3) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 5%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the primary coated product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. Keep the mixed solution at a constant temperature of 60 ± 3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle. The mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the primary coated product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin:primary coated product = 1.5:1. After the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180 ± 2 °C, keep it warm and stir magnetically for 20 h, then air-cool it to room temperature, open the reaction kettle, separate the solid and liquid, wash the solid with ethanol, and dry it to obtain the alumina-based catalyst of this comparative example.

[0054] Comparative Example 3

[0055] An alumina-based catalyst, and its preparation method includes the following steps:

[0056] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 13 g / 100 mL, and the solvent is ethanol. Keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60 ± 2 °C in a water bath, and carry out condensation reflux during the constant temperature process. Stir the ethanol solution of aluminum sec-butoxide at 50 r / min. Add deionized water to the ethanol solution of aluminum sec-butoxide under stirring. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water is ethanol solution of aluminum sec-butoxide:deionized water = 1:1. After the feeding is completed, continue stirring for 100 min, then separate the solid and liquid, dry the solid in an environment of 70 °C for 20 h, then calcine it at a temperature of 550 °C for 6 h, and after the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix.

[0057] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30. Keep the dispersion in a water bath at a constant temperature of 80 ± 3 °C for heat preservation. Stir the dispersion at 50 r / min under the heat preservation state. While stirring, add silica sol to the dispersion. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 50 min at 80 ± 3 °C. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.8:0.4:1. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 30 min at 80 ± 3 °C. Then, let it stand in the air for 20 h. After the standing is completed, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool it to room temperature. Open the reaction kettle, perform solid-liquid separation. Wash the solid phase with deionized water 3 times, dry it at 100 °C for 1 h, then place it in a muffle furnace at 500 °C for calcination for 4 h, and air-cool it to room temperature to obtain a primary coated product;

[0058] (3) Prepare an ethanol solution of iridium chloride. The mass percentage of iridium chloride in the ethanol solution of iridium chloride is 5%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of iridium chloride for 1 min. The solid-liquid mass ratio of immersing the primary coated product in the ethanol solution of iridium chloride is solid / liquid = 1:30. Then perform solid-liquid separation. Dry the solid phase at 100 °C for 10 min, and then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. Immerse it again in the ethanol solution of iridium chloride for 1 min. After immersion, perform solid-liquid separation. Dry the solid phase again at 100 °C for 10 min, and then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. One set of the above immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is an overall combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine it in a muffle furnace at 450 °C for 1 h, and then air-cool it to room temperature to obtain an iridium oxide-loaded product;

[0059] (4) Add ethanol into the reaction kettle; immerse the iridium oxide-loaded product in the ethanol, and the solid-liquid mass ratio of the iridium oxide-loaded product immersed in ethanol is solid / liquid = 1:20; keep the mixed solution at a constant temperature of 60±3 °C in a water bath and stir for 30 min. During the stirring process, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin into the reaction kettle, and the mass ratio of copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide-loaded product is copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin: iridium oxide-loaded product = 1.5:1; after the feeding is completed, seal the reaction kettle, fill it with nitrogen for protection, then heat it to 180±2 °C, keep it warm and stir magnetically for 20 h, then air-cool it to room temperature, open the reaction kettle, separate the solid and liquid, wash the solid with ethanol, and dry it to obtain the alumina-based catalyst of this comparative example.

[0060] Comparative Example 4

[0061] An alumina-based catalyst, and its preparation method includes the following steps:

[0062] (1) Prepare an ethanol solution of aluminum sec-butoxide. In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 13 g / 100 mL, and the solvent is ethanol; keep the ethanol solution of aluminum sec-butoxide at a constant temperature of 60±2 °C in a water bath, and carry out condensation reflux during the constant temperature process; stir the ethanol solution of aluminum sec-butoxide at 50 r / min, and add deionized water into the ethanol solution of aluminum sec-butoxide under the stirring state. The volume ratio of the ethanol solution of aluminum sec-butoxide to deionized water is ethanol solution of aluminum sec-butoxide: deionized water = 1:1; after the feeding is completed, continue to stir for 100 min, then separate the solid and liquid, dry the solid at 70 °C for 20 h, then calcine it at 550 °C for 6 h, and after the calcination is completed, air-cool it to room temperature to obtain the aluminum oxide matrix;

[0063] (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion. The solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30. Keep the dispersion in a water bath at a constant temperature of 80 ± 3 °C for heat preservation. Stir the dispersion at 50 r / min under the heat preservation state. While stirring, add silica sol to the dispersion. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 50 min at 80 ± 3 °C. Then, while stirring, add N,N-diisopropylethylamine to the dispersion. The mass ratio of the added silica sol, N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.8:0.4:1. After the feeding is completed, continue to keep the dispersion in heat preservation and stir for 30 min at 80 ± 3 °C. Then, let it stand in the air for 20 h. After standing, seal the reaction kettle, heat it to 160 ± 3 °C for heat preservation for 60 h, then air-cool it to room temperature. Open the reaction kettle, perform solid-liquid separation. Wash the solid phase with deionized water 3 times, dry it at 100 °C for 1 h, then place it in a muffle furnace at 500 °C for calcination for 4 h, and air-cool it to room temperature to obtain a primary coated product;

[0064] (3) Prepare an ethanol solution of iridium chloride. The mass percentage of iridium chloride in the ethanol solution of iridium chloride is 5%, and the solvent is ethanol. Immerse the primary coated product in the ethanol solution of iridium chloride for 1 min. The solid-liquid mass ratio of immersing the primary coated product in the ethanol solution of iridium chloride is solid / liquid = 1:30. Then perform solid-liquid separation. Dry the solid phase at 100 °C for 10 min, then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. Immerse it again in the ethanol solution of iridium chloride for 1 min. After immersion, perform solid-liquid separation. Dry the solid phase again at 100 °C for 10 min, then place it in a muffle furnace at 450 °C for calcination for 15 min. After calcination, air-cool it to room temperature. One set of the above immersion, solid-liquid separation, drying, calcination, and air-cooling process steps is an overall combined process. Repeat the above combined process for a total of 8 groups. Finally, calcine it in a muffle furnace at 450 °C for 1 h, and then air-cool it to room temperature to obtain an iridium oxide-loaded product;

[0065] (4) An ethanol solution of γ-aminopropyltriethoxysilane is prepared in a reaction kettle. In the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 5%, and the solvent is ethanol. The iridium oxide-loaded product is immersed in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution. The solid-liquid mass ratio of the iridium oxide-loaded product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20. The mixed solution is kept at a constant temperature of 60 ± 3 °C in a water bath, stirred for 30 min, then the reaction kettle is sealed, filled with nitrogen for protection, then heated to 180 ± 2 °C, kept warm and magnetically stirred for 20 h, then air-cooled to room temperature, the reaction kettle is opened, solid-liquid separation is carried out, the solid phase is washed with ethanol and dried to obtain the alumina-based catalyst of this comparative example.

[0066] Example 5

[0067] The catalytic performance of the catalysts prepared by the methods of the above examples and comparative examples was tested. The test method was as follows: The cyclohexene epoxidation reaction was catalyzed by the catalysts prepared by the methods of the above examples and comparative examples respectively. Cyclohexene, alumina-based catalyst, cumene hydroperoxide and acetonitrile were mixed and reacted. The mixing mass ratio was olefin: alumina-based catalyst: alkyl peroxide: reaction solvent = 15:2:6:100. The reaction temperature was 65 °C and the reaction time was 7 h. Stirring was carried out under reflux during the reaction. After the reaction was completed, the product was analyzed to determine the composition and content of the product, and the conversion rate and the selectivity of cyclohexene oxide were calculated. The conversion rate = the amount of consumed cyclohexene / the total amount of cyclohexene, and the selectivity = the amount of cyclohexene oxide in the product / the amount of consumed cyclohexene. The results are shown in Table 1.

[0068] As can be seen from Table 1, the catalyst prepared by the method of the present invention has a good catalytic effect on the olefin epoxidation reaction, greatly improves the conversion rate of olefins, makes the reaction more complete, and has a high selectivity for the target product epoxide and relatively few reaction by-products.

[0069] Table 1

[0070] Experimental group Conversion rate of cyclohexene Selectivity of cyclohexene oxide Example 1 92.2％ 87.8％ Example 2 92.6％ 88.0％ Example 3 92.9％ 87.5％ Example 4 93.1％ 87.3％ Comparative example 1 73.5％ 80.2％ Comparative example 2 71.8％ 82.7％ Comparative example 3 80.4％ 83.6％ Comparative example 4 78.7％ 82.1％

[0071] The technical solutions provided by the present invention have been introduced in detail above. For those of ordinary skill in the art, according to the idea of the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An alumina-based catalyst, characterized in that, The preparation method comprises the following steps: (1) Prepare an ethanol solution of aluminum sec-butoxide, keep the ethanol solution of aluminum sec-butoxide in a water bath at a constant temperature of 60±2°C, and carry out condensation reflux during the constant temperature process; stir the ethanol solution of aluminum sec-butoxide, add deionized water to the ethanol solution of aluminum sec-butoxide under stirring, continue stirring for more than 100 min after the feeding is completed, then carry out solid-liquid separation, dry the solid phase at 70°C for more than 20 h, then calcine it at a temperature of 550-560°C for 6-7 h, and cool it to room temperature in air after calcination to obtain an aluminum oxide matrix; (2) Disperse the aluminum oxide matrix in deionized water in a reaction kettle to form a dispersion, keep the dispersion in a water bath at a constant temperature of 80±3°C for heat preservation, stir the dispersion under the heat preservation state, add silica sol to the dispersion under stirring, continue to keep the dispersion at 80±3°C for heat preservation and stirring for more than 50 min after the feeding is completed, then add N,N-diisopropylethylamine to the dispersion under stirring, continue to keep the dispersion at 80±3°C for heat preservation and stirring for more than 30 min after the feeding is completed, then let it stand in air for more than 20 h, close the reaction kettle after standing, heat it to 160±3°C for heat preservation for more than 60 h, then cool it to room temperature in air, carry out solid-liquid separation, wash the solid phase with deionized water for more than 3 times, dry it at 100°C for more than 1 h, then calcine it in a muffle furnace at 500-530°C for 3-4 h, and cool it to room temperature in air to obtain a primary coated product; (3) Prepare an ethanol solution of chloroiridic acid, soak the primary coated product in the ethanol solution of chloroiridic acid for 1 min, then carry out solid-liquid separation, dry the solid phase at 100-110°C for more than 10 min, then calcine it in a muffle furnace at 450°C for more than 15 min, cool it to room temperature in air after calcination, soak it in the ethanol solution of chloroiridic acid again for 1 min, carry out solid-liquid separation after soaking, dry the solid phase again at 100-110°C for more than 10 min, then calcine it in a muffle furnace at 450°C for more than 15 min, cool it to room temperature in air after calcination. One set of the above-mentioned soaking, solid-liquid separation, drying, calcination and air cooling process steps is an overall combined process. Repeat the above combined process for more than 8 groups. Finally, calcine it in a muffle furnace at 450°C for more than 1 h, and then cool it to room temperature in air to obtain an iridium oxide-supported product; (4) Prepare an ethanol solution of γ-aminopropyltriethoxysilane in a reaction kettle, soak the iridium oxide-supported product in the ethanol solution of γ-aminopropyltriethoxysilane to obtain a mixed solution, keep the mixed solution in a water bath at a constant temperature of 60±3°C for heat preservation and stirring for more than 30 min, add copper(II) meso-tetrakis(4-carboxyphenyl)porphyrin to the reaction kettle during the stirring process, close the reaction kettle after the feeding is completed, fill it with nitrogen for protection, then heat it to 180±2°C for heat preservation and magnetic stirring for more than 20 h, then cool it to room temperature in air, open the reaction kettle, carry out solid-liquid separation, wash the solid phase with ethanol, and dry it to obtain the alumina-based catalyst.

2. The alumina-based catalyst according to claim 1, wherein In the ethanol solution of aluminum sec-butoxide, the concentration of aluminum sec-butoxide is 10-20 g / 100 mL, and the solvent is ethanol; the volume ratio of deionized water added to the ethanol solution of aluminum sec-butoxide is ethanol solution of aluminum sec-butoxide:deionized water = 1:1-2.

3. The alumina-based catalyst according to claim 1, wherein In the step (2), the solid-liquid mass ratio of dispersing the aluminum oxide matrix in deionized water is solid / liquid = 1:30; the mass ratio of the added silica sol and N,N-diisopropylethylamine to the mass of the aluminum oxide matrix in the dispersion is silica sol:N,N-diisopropylethylamine:aluminum oxide matrix = 0.6-1.4:0.4-0.5:

1.

4. An alumina-based catalyst according to claim 1, characterized in that, In the step (3), the mass percentage of chloroiridic acid in the ethanol solution of chloroiridic acid is 5%-6%, and the solvent is ethanol; the solid-liquid mass ratio of the primary coated product immersed in the ethanol solution of chloroiridic acid is solid / liquid = 1:

30.

5. An alumina-based catalyst according to claim 1, characterized in that, In the step (4), in the ethanol solution of γ-aminopropyltriethoxysilane, the mass percentage of γ-aminopropyltriethoxysilane is 4%-6%, and the solvent is ethanol; the solid-liquid mass ratio of the iridium oxide supported product immersed in the ethanol solution of γ-aminopropyltriethoxysilane is solid / liquid = 1:20; the mass ratio of adding copper Meso-tetrakis(4-carboxyphenyl)porphyrin to the iridium oxide supported product is copper Meso-tetrakis(4-carboxyphenyl)porphyrin:iridium oxide supported product = 1.2-1.7:

1.

6. Use of the alumina-based catalyst according to any one of claims 1 to 5 in an olefin epoxidation reaction, characterized in that, Mix an olefin, the alumina-based catalyst, an alkyl peroxide and a reaction solvent for reaction, the reaction temperature is 30-70 °C, and the reaction time is 7-8 h.

7. Use of an alumina-based catalyst according to claim 6 in an olefin epoxidation reaction, characterized in that, The alkyl peroxide is any one of tert-butyl hydroperoxide and cumene hydroperoxide; the reaction solvent is one of acetonitrile, cyclohexane or tert-butanol; the olefin is a C3-C8 linear olefin or cycloolefin.

8. Use of an alumina-based catalyst according to claim 6 in an olefin epoxidation reaction, characterized in that, The mixing mass ratio of the olefin, the alumina-based catalyst, the alkyl peroxide and the reaction solvent is olefin:alumina-based catalyst:alkyl peroxide:reaction solvent = 15-20:1-3:6-8:100.