α-Aluminum Oxide Support, α-Aluminum Oxide-Based Catalyst and Preparation Method and Application Thereof

Abstract

The present invention provides an α-alumina support, an α-alumina-based catalyst, and a preparation method and application thereof, comprising the following steps: (1) mixing a silicon-modified fiber material, hydrated alumina, a first auxiliary agent, and a fluorine-containing inorganic salt to obtain a mixture; wherein the mass components of each component are: 1000 parts of hydrated alumina, 1-3 parts of the first auxiliary agent, 15-35 parts of the silicon-modified fiber material, 10-30 parts of the fluorine-containing inorganic salt, and the first auxiliary agent comprises a compound of at least one element in Groups IIA, IVA, VIIA, IIB, IIIB, and IVB of the periodic table; (2) mixing and molding the mixture obtained in step (1), a binder, and an extrusion aid, and drying and calcining to obtain the α-alumina support; wherein the mass components of the mixture, the binder, and the extrusion aid are: 1000 parts of the mixture, 50-200 parts of the binder, and 5-20 parts of the extrusion aid. The α-alumina support provided by the present invention not only has high mechanical strength but also has pores that are not prone to shrinkage and have low tortuosity.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to an α-aluminum oxide support, an α-aluminum oxide-based catalyst, and a preparation method and application thereof. Background Art

[0002] Ethylene oxide is an important derivative of ethylene, mainly used in the production of chemical raw materials such as ethylene glycol and polyether monomers, and is an important chemical product today. The main method for producing ethylene oxide is through an epoxidation reaction under the action of a silver catalyst. The silver catalyst consists of a support and a silver active component supported on the support. Using a silver catalyst with excellent performance helps to produce ethylene oxide. In addition to providing a loading platform for the active component, the support also provides a transport channel for the internal diffusion process of the molecules involved in the catalytic conversion reaction. Reactant molecules enter the pores through diffusion, diffuse along the pores of the support, and randomly adsorb on the active component within the pores to undergo a catalytic reaction to form ethylene oxide. The formed ethylene oxide then leaves the internal space of the silver catalyst via the pores. If the internal pores of the silver catalyst are relatively tortuous, that is, the tortuosity factor is high, the diffusion resistance of ethylene oxide molecules is greater, the time to leave the catalyst is longer, and the probability of being deeply oxidized to form carbon oxides will increase, resulting in a decrease in the selectivity of ethylene oxide. Therefore, the pore structure and surface chemical properties of the support have an important impact on molecular diffusion and mass transfer. Improving the pore structure of the support is one of the important means to improve the performance of the catalyst.

[0003] Currently, the support material of the silver catalyst applied in industry often selects an α-aluminum oxide (α-Al2O3) support. When preparing the α-aluminum oxide support, high-temperature calcination is required. During the high-temperature calcination process, the densification rate of α-aluminum oxide will be accelerated, resulting in a reduction in the internal pores of α-aluminum oxide. The reduction of pores is not conducive to the diffusion of reactants, thereby affecting the selectivity of ethylene oxide.

[0004] The prior art usually introduces pore-forming agents during the preparation of the support, such as rice husks, graphite, corn carbon, carboxymethyl cellulose, ethyl cellulose, etc., to promote the formation of more internal diffusion pores in the support. However, the following problems exist in the application: First, the pore-forming agent forms cavities through burnout, and the cavities are connected to form pores. The pore tortuosity factor of the pores prepared using the above-mentioned pore-forming agents is relatively high, which is not conducive to the diffusion of reactants and products. Second, the burnout temperature of the pore-forming agent is relatively low. The burnout process of the pore-forming agent generally occurs before the densification process of alumina. As the calcination temperature increases, the pores will shrink significantly or even close to form dead pores, making it difficult to effectively control the pore structure of the support and seriously affecting the pore-forming effect. Third, if a higher proportion of pore-forming agent is added, it will affect the mechanical strength of the support, making it unable to meet the filling requirements and usage requirements of industrial reactors.

[0005] Therefore, how to provide a preparation method of an α-aluminum oxide carrier, while ensuring its high mechanical strength and promoting the formation of low tortuosity pores inside the α-aluminum oxide carrier, is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0006] The present invention provides an α-aluminum oxide carrier, an α-aluminum oxide-based catalyst, and their preparation methods and applications. The prepared carrier not only has high mechanical strength but also has pores with low shrinkage and low tortuosity. Therefore, when the α-aluminum oxide carrier is used as a carrier for a supported silver catalyst, the catalytic activity of the catalyst can be improved, effectively overcoming the defects existing in the prior art.

[0007] In the first aspect of the present invention, a preparation method of an α-aluminum oxide carrier is provided, including the following steps: (1) Mix a silicon-modified fiber material, hydrated alumina, a first auxiliary agent, and a fluorine-containing inorganic salt to obtain a mixture; the mass components of each component are: 1000 parts of hydrated alumina, 1-3 parts of the first auxiliary agent, 15-35 parts of the silicon-modified fiber material, and 10-30 parts of the fluorine-containing inorganic salt. The first auxiliary agent includes compounds of at least one element in Groups IIA, IVA, VIIA, IIB, IIIB, and IVB of the periodic table; (2) Mix the mixture obtained in step (1), a binder, an extrusion aid, and water, then perform a shaping process, and obtain the α-aluminum oxide carrier after drying and calcination; the mass components of the mixture, the binder, and the extrusion aid are: 1000 parts of the mixture, 50-200 parts of the binder, and 5-20 parts of the extrusion aid.

[0008] According to an embodiment of the present invention, the hydrated alumina includes at least one of boehmite, pseudo-boehmite, and trihydrate alumina; and / or, the first auxiliary agent includes a compound of at least one element among Ca, Sr, Ba, Si, Zn, Zr, Y, and F; and / or, the inorganic fluoride salt includes at least one of ammonium fluoride and aluminum fluoride; and / or, the extrusion aid includes at least one of white oil, paraffin, vaseline, stearic acid, and sesbania powder; and / or, the binder includes at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, and citric acid; and / or, the mass of the binder accounts for 20%-50% of the sum of the mass of the binder and the mass of the water; and / or, the conditions of the drying treatment: the temperature is 100°C - 200°C, and the time is 2h - 12h; and / or, the conditions of the roasting treatment: the temperature is 1200°C - 1400°C, and the time is 5h - 8h; and / or, in step (2), through mixing and forming, the formed product is a granular product, and the granular product includes at least one of Raschig ring-shaped particles, cylindrical particles without pores in the middle, and cylindrical particles with a porous structure. The Raschig ring-shaped particles satisfy: the outer diameter is 5mm - 10mm, the particle length is 5mm - 10mm, and the middle hole diameter is 1.5mm - 4.5mm.

[0009] According to an embodiment of the present invention, the preparation process of the silicon-modified fiber material includes: soaking the vegetable cellulose material in an alcohol solution for more than 12h, and after solid-liquid separation, obtaining a first solid and a first liquid respectively; drying the first solid at 100°C - 120°C for 4h - 8h to obtain the dried first solid; wherein the mass ratio of the vegetable cellulose material to the alcohol solution is 1:2 - 10; adding an amine solution to the first liquid, adjusting the pH to 7.5 - 10, and then adding a silicate ester to make a silica sol containing lignin; wherein the mass ratio of the silicate ester to the alcohol solution is 1:10 - 200; mixing the dried first solid with the silica sol containing lignin, and then drying at 60°C - 120°C for more than 12h to obtain the silicon-modified fiber material.

[0010] According to an embodiment of the present invention, the alcohol solution includes at least one of methanol, ethanol, ethylene glycol, and propanol; and / or, the mass concentration of the alcohol compound in the alcohol solution is 10% - 90%; and / or, the amine solution includes ammonia water and / or organic amine, and the organic amine includes at least one of ethylamine, ethylenediamine, ethanolamine, and n-butylamine; and / or, the mass concentration of the amine compound in the amine solution is 3% - 10%; and / or, the silicate ester includes at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0011] In the second aspect of the present invention, an α-alumina carrier is provided, which is prepared by the above preparation method.

[0012] In a third aspect of the present invention, there is provided a method for preparing a silver-loaded α-alumina-based catalyst, comprising the following steps: preparing an α-alumina support according to the above-mentioned preparation method; impregnating the α-alumina support with an impregnating solution containing a silver source to obtain a silver-loaded α-alumina-based catalyst.

[0013] According to an embodiment of the present invention, the silver source includes silver oxalate, and the impregnating solution is prepared according to a process including the following steps: dissolving silver oxalate in an organic amine solution and adding a second auxiliary agent thereto to obtain the impregnating solution; wherein the second auxiliary agent includes a compound formed by at least one element selected from alkali metals, alkaline earth metals, and transition metals.

[0014] In a fourth aspect of the present invention, there is provided a silver-loaded α-alumina-based catalyst, comprising a support and a silver component supported on the support, wherein the support includes the above-mentioned α-alumina support.

[0015] In a fifth aspect of the present invention, there is provided a silver-loaded α-alumina-based catalyst, which is prepared according to a preparation process including the following steps: dissolving silver oxalate in an organic amine solution and adding a second auxiliary agent thereto to obtain the impregnating solution; wherein the second auxiliary agent includes a compound formed by at least one element selected from alkali metals, alkaline earth metals, and transition metals; impregnating the above-mentioned α-alumina support with the impregnating solution to obtain a silver-loaded α-alumina-based catalyst.

[0016] In a sixth aspect of the present invention, there is provided a method for preparing ethylene oxide, comprising: subjecting an ethylene raw material to an epoxidation reaction under the action of a catalyst to obtain ethylene oxide, wherein the catalyst includes a silver-loaded α-alumina-based catalyst prepared according to the above-mentioned preparation method or the above-mentioned silver-loaded α-alumina-based catalyst.

[0017] The implementation of the present invention has at least the following beneficial effects:

[0018] In the preparation method of the α-alumina support provided by the present invention, a silicon-modified fibrous material is used as a pore-forming agent. The silicon-modified fibrous material is in close contact with hydrated alumina and the like through mixing and shaping processes and then shaped. After calcination, pores are formed during the calcination process. At the same time, silicon on the surface of the silicon-modified fibrous material gradually diffuses into the alumina lattice to form a mullite phase with an elemental composition of Al-Si-O on the inner surface of the pores. The mullite phase has a relatively high strength, which can play a role in supporting the pores, preventing the pores from shrinking and reducing the occurrence of closed pores, thereby effectively controlling the pore structure of the support. In addition, the silicon-modified fibrous material has a long and straight-through fibrous structure. After calcination, the formed pores have little tortuosity. When the α-alumina support is used as a support for a supported metal catalyst, it is beneficial to the diffusion of reactants in the pores and improves the selectivity of the product.

[0019] In addition, the preparation method of the α-aluminum oxide support provided by the present invention also has the advantages of simple preparation process, controllable process conditions, easy operation, etc., which is conducive to industrial production and application. Specific Embodiments

[0020] The specific embodiments listed below only describe the principles and features of the present invention. The examples given are only used to explain the present invention and do not limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] The preparation method of the α-aluminum oxide support provided by the present invention includes the following steps: (1) Mixing a silicon-modified fiber material, hydrated alumina, a first auxiliary agent, and a fluorine-containing inorganic salt to obtain a mixture; the mass components of each component are: 1000 parts of hydrated alumina, 1-3 parts of the first auxiliary agent, 15-35 parts of the silicon-modified fiber material, 10-30 parts of the fluorine-containing inorganic salt, and the first auxiliary agent includes a compound of at least one element in Groups IIA, IVA, VIIA, IIB, IIIB, and IVB of the periodic table; (2) Mixing the mixture obtained in step (1), a binder, an extrusion aid, and water, and then performing a shaping process, followed by drying and calcination to obtain the α-aluminum oxide support; the mass components of the mixture, the binder, and the extrusion aid are: 1000 parts of the mixture, 50-200 parts of the binder, and 5-20 parts of the extrusion aid.

[0022] In the present invention, the silicon-modified fiber material is a plant-based cellulose material modified with silicon and has a long fiber structure. In step (1), based on 1000 parts of hydrated alumina, the first auxiliary agent is 1-3 parts, such as 1 part, 1.3 parts, 1.5 parts, 2 parts, 2.1 parts, 2.5 parts, 3 parts or the range composed of any two of them; the silicon-modified fiber material is 15-35 parts, such as 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or the range composed of any two of them; the fluorine-containing inorganic salt is 10-30 parts, such as 10 parts, 15 parts, 20 parts, 25 parts, 30 parts or the range composed of any two of them. In step (2), based on 1000 parts of the mixture obtained in step (1), the binder is 50-200 parts, such as 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 87.5 parts, 90 parts, 95 parts, 100 parts, 105 parts, 150 parts, 180 parts, 190 parts, 200 parts or the range composed of any two of them; the extrusion aid is 5-20 parts, such as 5 parts, 10 parts, 11 parts, 12 parts, 70 parts, 75 parts, 80 parts, 85 parts, 87.5 parts, 90 parts, 95 parts, 100 parts, 105 parts, 150 parts, 180 parts, 190 parts, 200 parts or the range composed of any two of them. Generally, hydrated alumina refers to a precursor compound that can form various crystalline phase aluminas after dehydration by heat treatment. Compared with alumina, when using hydrated alumina as the raw material for preparing the α-alumina support, hydrated alumina has better formability, and the physical and chemical properties of the product can be regulated by means of heat treatment, doping, etc. In some embodiments, the hydrated alumina includes at least one of boehmite, pseudoboehmite, and trihydrate alumina, and a combination of pseudoboehmite and trihydrate alumina is preferred.

[0023] In the present invention, the first additive is used to further improve the mechanical strength of the carrier. In some embodiments, the first additive includes a compound of at least one element selected from Ca, Sr, Ba, Si, Zn, Zr, Y, and F, wherein the compound includes inorganic salts and / or oxides. In the specific implementation process of the present invention, the oxides include at least one of calcium oxide, silicon oxide, iridium dioxide, and zirconium oxide, and the inorganic salts include at least one of strontium nitrate and barium sulfate. Element atoms in the first additive, such as Ca, Si, Y, etc., can combine with Al and O to form a low-melting-point solid solution composite oxide, which helps to improve the strength of the carrier. At the same time, during the subsequent calcination (sintering) process, not only α-Al2O3 can be formed, but also a composite oxide of Al-X-O can be formed, where X is a metal element in the first additive. The structures of these composite oxides are different from the structure of the mainly existing Al2O3 around, and can be called sub-structures relative to alumina. These sub-structures can form protrusions or depressions on the surface of α-Al2O3 micro-particles, thereby reducing the flatness of the crystal planes of α-Al2O3 micro-particles, causing resistance to the movement and aggregation of metal micro-particles such as silver loaded on the crystal planes, thereby increasing the energy barrier of metal aggregation and prolonging the service life.

[0024] Generally, fluorine-containing inorganic salts are used to lower the crystal transformation temperature of α-alumina and increase the transformation rate of hydrated alumina to α-alumina. In some embodiments, the fluorine-containing inorganic salts include at least one of ammonium fluoride and aluminum fluoride.

[0025] In some embodiments, the process of mixed molding includes: mixing the mixture, binder, extrusion aid, and water, and then performing molding treatment; wherein, the mass of the binder accounts for 20%-50% of the sum of the mass of the binder and the mass of water, such as 20%, 22%, 25%, 28%, 30%, 33%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, or a range composed of any two of them. In the specific implementation process of the present invention, the binder is first mixed with water to form a binder solution, and then the mixture, binder solution, and extrusion aid are mixed, and then molding treatment is performed, wherein the mass concentration of the binder in the binder solution is 20%-50%. Based on 1000 parts of the mixture, the binder solution is 250-500 parts, such as 250 parts, 300 parts, 320 parts, 350 parts, 380 parts, 400 parts, 420 parts, 450 parts, 480 parts, 500 parts, or a range composed of any two of them.

[0026] Generally, the binder includes inorganic acids and / or organic acids, that is, the binder solution includes inorganic acid solutions and / or organic acid solutions. In some embodiments, the binder includes at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, and citric acid.

[0027] Specifically, during the process of mixing the mixture, the binder solution, and the extrusion aid, the hydrated alumina in the mixture and the binder solution can form an aluminum sol, which has adhesiveness and further enables adhesiveness to be obtained between the reaction raw materials.

[0028] In the present invention, the function of the extrusion aid is to reduce the friction and adhesion of the reaction raw materials during the shaping process, which is helpful for the subsequent shaping process. In some embodiments, the extrusion aid includes at least one of white oil, paraffin wax, petrolatum, stearic acid, and sesbania powder.

[0029] In the present invention, the shaping process can be carried out in a shaping device. The shaping process can be directly tablet-shaped, or can be carried out by first extruding into strips and then slicing. In some embodiments, in step (2), through mixed shaping, the shaped product formed is a granular product, and the granular product includes at least one of granular products in the shape of Raschig rings, cylindrical particles without holes in the middle, and cylindrical particles with a porous structure. Among them, the Raschig ring is a cylinder with a middle hole, and the granular product in the shape of Raschig rings satisfies: the outer diameter is 5 mm - 10 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a range composed of any two of them; the particle length is 5 mm - 10 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, or a range composed of any two of them; the middle hole diameter is 1.5 mm - 4.5 mm, such as 1.5 mm, 1.8 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or a range composed of any two of them.

[0030] In the present invention, the drying process is to remove a large amount of free water in the shaped product to avoid adverse effects on the mechanical strength of the carrier and the roasting equipment caused by the volatilization of a large amount of water vapor during the subsequent roasting process. The drying method adopts conventional drying means in the art. For example, drying can be carried out using a track dryer, or hot air can be used for drying, or an oven can be used for drying, but it is not limited thereto. In some embodiments, the conditions of the drying process are: the temperature is 100°C - 200°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or a range composed of any two of them; the time is 2 h - 12 h, such as 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, or a range composed of any two of them.

[0031] In the present invention, through calcination treatment, hydrated alumina is dehydrated and undergoes a phase change at high temperature to be transformed into α-alumina. In addition, the silicon-modified fiber material is used as a pore-forming agent and contacts with the hydrated alumina. During the calcination process, the silicon-modified fiber material gradually burns out to form cavities, and the cavities are connected to form pore channels. At the same time, silicon on the surface of the silicon-modified fiber material gradually diffuses into the alumina lattice to form a mullite phase with an element composition of Al-Si-O on the inner surface of the pore channels, which is used to support the pore channels. The fiber structure in the silicon-modified fiber material is straight. After calcination, the formed pore channels have little tortuosity, which promotes the obtained α-alumina carrier to have a low tortuosity factor. Generally, the calcination treatment is carried out in a calcination device, and the calcination device includes one of a muffle furnace, a tunnel kiln, and a bell jar kiln.

[0032] Specifically, the calcination treatment can be carried out in an inert atmosphere and / or an oxygen-containing atmosphere. The oxygen-containing atmosphere is, for example, air. For example, the calcination treatment is carried out in an inert atmosphere with added oxygen, and the inert atmosphere contains an inert gas, and the inert gas includes at least one of nitrogen, argon, and helium.

[0033] In some embodiments, the conditions of the calcination treatment are as follows: the temperature is 1200°C - 1400°C, such as 1200°C, 1210°C, 1220°C, 1230°C, 1240°C, 1250°C, 1260°C, 1270°C, 1280°C, 1290°C, 1300°C, 1320°C, 1330°C, 1340°C, 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C or a range composed of any two of them; the time is 5h - 8h, such as 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h or a range composed of any two of them. The process of the calcination treatment includes placing the dried formed product in the calcination device, heating the calcination device at a heating rate of 2°C / min to 20°C / min to 1200°C - 1400°C, maintaining for 5h - 8h, and naturally cooling to room temperature to obtain the α-alumina carrier. The heating rate is preferably 3°C / min - 18°C / min, such as 3°C / min, 4°C / min, 6°C / min, 8°C / min, 10°C / min, 12°C / min, 16°C / min, 18°C / min or a range composed of any two of them.

[0034] In some embodiments, the preparation process of the silicon-modified fiber material includes: soaking the vegetable cellulose material in an alcohol solution for more than 12 hours, and after solid-liquid separation, obtaining a first solid and a first liquid respectively; performing a first drying treatment on the first solid to obtain the dried first solid; adding an amine solution to the first liquid, adjusting the pH to 7.5 - 10, and then adding a silicate ester to prepare a silica sol containing lignin; mixing the dried first solid with the silica sol containing lignin, and after a second drying treatment, obtaining the silicon-modified fiber material.

[0035] Specifically, the vegetable cellulose material refers to materials rich in cellulose from plants, including but not limited to at least one of wood chips of woody plants, bamboo chips of bamboo subfamily plants, endocarp of mature fruits of Juglandaceae plants, and sunflower seed husks. Usually, the vegetable cellulose material is also pretreated, and then the treated vegetable cellulose material is soaked in an alcohol solution, wherein the pretreatment includes crushing the vegetable cellulose material so that it can pass through a 10-mesh sieve.

[0036] In the present invention, the mass ratio of the vegetable cellulose material to the alcohol solution is 1:2 - 10, such as 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or the range composed of any two of them.

[0037] Generally, the alcohol solution contains an alcohol compound, and the alcohol compound is mixed with water to form an alcohol solution. When the vegetable cellulose material is soaked in the alcohol solution, dissociation occurs, and at least lignin is formed. In some embodiments, the alcohol solution includes at least one of methanol, ethanol, ethylene glycol, and propanol. Further, the mass concentration of the alcohol compound in the alcohol solution is 10% - 90%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90% or the range composed of any two of them.

[0038] In the specific implementation process of the present invention, the solid-liquid separation adopts a conventional separation method in the art, such as suction filtration separation. After solid-liquid separation, a first solid and a first liquid are obtained. The first liquid contains at least lignin. A first drying treatment is performed on the first solid. The conditions of the first drying treatment are: temperature 100°C - 120°C, such as 100°C, 102°C, 105°C, 110°C, 115°C, 118°C, 120°C or the range composed of any two of them, and the time is 4h - 8h, such as 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h or the range composed of any two of them.

[0039] In the present invention, an amine solution is added to the first solution to adjust the pH to 7.5 - 10, such as pH being 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10 or a range composed of any two of them. Generally, the amine solution contains an amine compound, and the amine compound is mixed with water to form the amine solution. In some embodiments, the amine solution includes ammonia water and / or organic amine, and the organic amine includes at least one of ethylamine, ethylenediamine, ethanolamine, and n-butylamine. Further, the mass concentration of the amine compound in the amine solution is 3% - 10%, such as 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or a range composed of any two of them.

[0040] In the specific implementation process of the present invention, an amine solution is added to the first solution to adjust the pH to 7.5 - 10, and then a silicate ester is added. The process of adding the silicate ester can be to add the silicate ester drop by drop to form a lignin-containing silica sol. In some embodiments, the mass ratio of the silicate ester to the alcohol solution is 1:10 - 200, such as 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:100, 1:120, 1:150, 1:180, 1:200 or a range composed of any two of them. In some embodiments, the silicate ester includes at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0041] In the present invention, the dried first solid is mixed with the lignin-containing silica sol, and after the second drying treatment, a silicon-modified fiber material is obtained. After mixing the dried first solid with the lignin-containing silica sol, it is left standing for 24 h, and then the second drying treatment is carried out to form a block. Then the block is crushed to pass through a sieve with 10 - 40 meshes, and the product is collected to obtain the silicon-modified fiber material.

[0042] In some embodiments, the conditions of the second drying treatment are: the temperature is 60°C - 120°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C, 115°C, 120°C or a range composed of any two of them, and the time is more than 12 h, such as 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 24 h or a range composed of any two of them.

[0043] The α-alumina support provided by the present invention is prepared by the above-mentioned preparation method. A mullite phase with an element composition of Al-Si-O is formed on the inner surface of the pores of the prepared α-alumina support. The mullite phase has high strength and can play a supporting role to prevent the pores from shrinking at high temperatures. Moreover, the pores of the α-alumina support have a small tortuosity. When used as a support for a supported metal catalyst, it can shorten the diffusion time of molecules and reduce the probability of the product being re-adsorbed for deep oxidation.

[0044] The preparation method of the silver-supported α-alumina-based catalyst provided by the present invention includes the following steps: preparing an α-alumina support according to the above-mentioned preparation method; impregnating the α-alumina support with an impregnating solution containing a silver source to obtain a silver-supported α-alumina-based catalyst.

[0045] In some embodiments, the silver source includes silver oxalate, and the impregnating solution is prepared according to a process including the following steps: dissolving silver oxalate in an organic amine solution and adding a second auxiliary agent thereto to obtain the impregnating solution; wherein the second auxiliary agent includes a compound formed by at least one element selected from alkali metals, alkaline earth metals, and transition metals.

[0046] Specifically, silver oxalate is obtained by a conventional method in the art. For example, a silver salt, a compound containing an oxalate group, and water are mixed to obtain a precipitate product. After repeatedly washing and filtering the precipitate product until the filtrate is neutral, silver oxalate is obtained. In the specific implementation process of the present invention, a silver salt and a part of water are mixed to form a silver salt aqueous solution; a compound containing an oxalate group and another part of water are mixed to form an aqueous solution containing an oxalate group; then the silver salt aqueous solution and the aqueous solution containing an oxalate group are mixed to obtain a precipitate product.

[0047] Furthermore, the silver salt includes at least one of silver acetate, silver nitrate, silver carbonate, and silver lactate, and the compound containing an oxalate group includes at least one of oxalic acid and ammonium oxalate. In some embodiments, the organic amine solution contains an organic amine, and the organic amine and water are mixed to obtain the organic amine solution, wherein the organic amine includes at least one of ethylenediamine, ethanolamine, and 1,3-propanediamine.

[0048] In the present invention, the second auxiliary agent includes compounds formed by at least one element selected from alkali metals, alkaline earth metals, and transition metals, preferably a mixture of compounds formed by alkali metal elements, alkaline earth metal elements, and transition metal elements. Among them, the alkali metals include at least one of Li, K, Cs, and Rb, the alkaline earth metals include at least one of Ca, Sr, and Ba, and the transition metal elements include at least one of Re, Mo, Fe, Mn, Ni, and Co. In the impregnating solution, the addition amount of the alkali metal element is 0.01-0.05% of the mass of the impregnating solution, such as 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, or the range composed of any two of them; the addition amount of the alkaline earth metal element is 0.01-0.09% of the mass of the impregnating solution, such as 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.6%, 0.7%, 0.8%, 0.9%, or the range composed of any two of them; the addition amount of the transition metal element is 0.04%-0.05% of the mass of the impregnating solution, such as 0.04%, 0.042%, 0.043%, 0.045%, 0.046%, 0.047%, 0.048%, 0.049%, 0.05%, 1%, or the range composed of any two of them.

[0049] Generally, after the impregnating solution is left for 0.5 h - 1 h for stabilization, the α-alumina support is then impregnated in the impregnating solution. During this process, the temperature of the impregnating solution is maintained at 20°C - 40°C, such as 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 38°C, 40°C, or the range composed of any two of them. Among them, the impregnation process is carried out under normal pressure or vacuum conditions, and the excess impregnation method or the equal-volume impregnation method is used for impregnation.

[0050] In the present invention, an α-aluminum oxide support is impregnated with an impregnating solution containing a silver source to obtain an impregnated product. After the impregnated product is successively subjected to drying treatment and activation treatment, a silver-loaded α-aluminum oxide-based catalyst is obtained. Among them, the activation treatment process is to treat in an air stream at 150°C - 500°C or a steam-air stream with a water content of 1% - 100% for 2 - 30 minutes to obtain the catalyst. The activation treatment conditions are: temperature 150°C - 500°C, such as 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C or a range composed of any two of them. The time is 2 min - 30 min, such as 2 min, 5 min, 6 min, 8 min, 10 min, 15 min, 18 min, 20 min, 25 min, 26 min, 30 min or a range composed of any two of them, and the water vapor content is 1% - 100%. The activation treatment can be carried out in a mesh belt furnace, an oven and other devices, or hot air blowing can be used. The heating method adopts a conventional heating method, such as natural gas heating, electric heating, steam heating, infrared heating.

[0051] Generally, in the prepared silver-loaded α-aluminum oxide-based catalyst, the silver loading is 15% - 25%, such as 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% or a range composed of any two of them.

[0052] The silver-loaded α-aluminum oxide-based catalyst provided by the present invention includes a support and a silver component supported on the support, and the support includes the above-mentioned α-aluminum oxide support. Specifically, the silver-loaded catalyst further includes a promoter element, and the promoter element includes at least one of Cs and Re.

[0053] The silver-loaded α-aluminum oxide-based catalyst provided by the present invention is prepared according to a preparation process including the following steps: dissolving silver oxalate in an organic amine solution and adding a second promoter thereto to obtain an impregnating solution; wherein, the second promoter includes a compound formed by at least one element of alkali metal, alkaline earth metal, and transition metal; using the above impregnating solution to impregnate the α-aluminum oxide support to obtain a silver-loaded α-aluminum oxide-based catalyst.

[0054] The preparation method of ethylene oxide provided by the present invention includes: subjecting an ethylene raw material to an epoxidation reaction under the action of a catalyst to obtain ethylene oxide, wherein the catalyst includes the silver-loaded α-aluminum oxide-based catalyst prepared by the above preparation method or the above silver-loaded α-aluminum oxide-based catalyst. Using the above silver-loaded α-aluminum oxide-based catalyst, the oxidation product is more likely to undergo internal diffusion, reducing the residence time in the pores and avoiding deep oxidation, thereby improving the selectivity of the ethylene oxide product.

[0055] The present invention will be further described below through specific examples and comparative examples. Unless otherwise specified, the reagents, materials, and instruments used below are all conventional reagents, conventional materials, and conventional instruments, which can be obtained commercially, and the reagents and materials involved can also be obtained by conventional synthesis methods.

[0056] In the following Examples 1-4, the following method was used to prepare the silicon-modified fiber material:

[0057] The vegetable fiber material was crushed to pass through a 10-mesh sieve to obtain powder, and then the powder was soaked in an alcohol solution for more than 12 h, separated by suction filtration to obtain a first solid and a first liquid; the first solid was dried at 110 °C for more than 6 h;

[0058] An amine solution was added to the first liquid, adjusted to 8.5, and then tetraethyl orthosilicate was added dropwise to form a lignin-containing silica sol;

[0059] The dried first solid was fully mixed with the lignin-containing silica sol, and then dried at 110 °C for more than 12 h to form a block, and then the block was crushed and screened to obtain powder between 10 and 40 meshes; the silicon-modified fiber material was obtained;

[0060] Among them, the silicon-modified fiber materials prepared in Examples 1-4 were respectively denoted as pore-forming agents A, B, C, and D. The types of vegetable fiber materials, alcohol solutions, and amine solutions selected in the preparation processes of Examples 1-4, as well as the mass concentration P1 of the alcohol solution, the powder mass M1, the mass M2 of the alcohol solution, the mass concentration P2 of the amine solution, and the mass M3 of the tetraethyl orthosilicate are shown in Table 1;

[0061] The sunflower seed husks, bamboo chips, wood chips, and walnut shells were respectively crushed and screened to obtain powder between 10 and 40 meshes, denoted as pore-forming agents E, F, G, and H.

[0062] Example 1

[0063] 25 g of pore-forming agent A, 250 g of pseudo-boehmite, 750 g of aluminum trihydrate, 1.9 g of barium oxide, 15 g of ammonium fluoride, and 1.1 g of zinc oxide were mixed to obtain a mixture. Then, the mixture, 350 g of acetic acid aqueous solution, and 8 g of sesbania powder were mixed and formed into Raschig ring particles. After drying and calcining the obtained particles, an α-aluminum oxide carrier was obtained, denoted as carrier A; the size of the particles was: outer diameter 5 mm, particle length 5 mm, and mesopore diameter 1.5 mm; the drying conditions were: temperature 120 °C, time 2 h; the calcining conditions were: temperature 1300 °C, time 6 h; the mass concentration of the acetic acid aqueous solution was 30%.

[0064] Example 2

[0065] 20 g of pore former B, 400 g of pseudoboehmite, 600 g of aluminum trihydroxide, 1.5 g of calcium oxide, 25 g of ammonium fluoride, and 1 g of silicon oxide were mixed to obtain a mixture. Then, the mixture was mixed with 450 g of sulfuric acid aqueous solution and 10 g of white oil, and formed into Raschig ring particles. After drying and calcining the obtained particles, an α-aluminum oxide carrier, denoted as carrier B, was obtained; the particle size was: outer diameter 6 mm, particle length 6 mm, and mesopore diameter 2 mm; the drying conditions were: temperature 110 °C, time 4 h; the calcining conditions were: temperature 1400 °C, time 5 h; the mass concentration of the sulfuric acid aqueous solution was 35%.

[0066] Example 3

[0067] 30 g of pore former C, 350 g of pseudoboehmite, 650 g of aluminum trihydroxide, 0.5 g of iridium dioxide, 10 g of aluminum fluoride, and 0.8 g of strontium nitrate were mixed to obtain a mixture. Then, the mixture was mixed with 250 g of hydrochloric acid aqueous solution and 12 g of paraffin wax, and formed into Raschig ring particles. After drying and calcining the obtained particles, an α-aluminum oxide carrier, denoted as carrier C, was obtained; the particle size was: outer diameter 7 mm, particle length 7 mm, and mesopore diameter 2.5 mm; the drying conditions were: temperature 150 °C, time 3 h; the calcining conditions were: temperature 1200 °C, time 8 h; the mass concentration of the hydrochloric acid aqueous solution was 35%.

[0068] Example 4

[0069] 15 g of pore former C, 300 g of pseudoboehmite, 700 g of aluminum trihydroxide, 1.6 g of barium sulfate, 15 g of ammonium fluoride, and 0.5 g of zirconium oxide were mixed to obtain a mixture. Then, the mixture was mixed with 300 g of nitric acid aqueous solution and 9 g of vaseline, and formed into Raschig ring particles. After drying and calcining the obtained particles, an α-aluminum oxide carrier, denoted as carrier D, was obtained; the particle size was: outer diameter 8 mm, particle length 8 mm, and mesopore diameter 3 mm; the drying conditions were: temperature 110 °C, time 5 h; the calcining conditions were: temperature 1280 °C, time 7 h; the mass concentration of the sulfuric acid aqueous solution was 25%.

[0070] Comparative Example 1

[0071] The difference from Example 1 was that pore former A was replaced with pore former E, and other conditions remained unchanged, denoted as comparative carrier E.

[0072] Comparative Example 2

[0073] The difference from Example 2 was that pore former A was replaced with pore former F, and other conditions remained unchanged, denoted as comparative carrier F.

[0074] Comparative Example 3

[0075] The difference from Example 3 is that pore former A is replaced with pore former G, and other conditions remain unchanged, denoted as comparative carrier G.

[0076] Comparative Example 4

[0077] The difference from Example 4 is that pore former A is replaced with pore former H, and other conditions remain unchanged, denoted as comparative carrier H.

[0078] Comparative Example 5

[0079] The difference from Example 1 is that pore former A is not added, and other conditions remain unchanged, denoted as comparative carrier I.

[0080] Comparative Example 6

[0081] The difference from Example 1 is that pore former A is replaced with carboxymethyl cellulose, and other conditions remain unchanged, denoted as comparative carrier J.

[0082] The following preparation methods are respectively used to prepare the catalyst:

[0083] Mix a silver salt, an oxalate-containing compound, and water to obtain a precipitation product. After repeatedly washing and filtering the precipitation product until the filtrate is neutral, silver oxalate is obtained; wherein the silver salt includes at least one of silver acetate, silver nitrate, silver carbonate, and silver lactate, and the oxalate-containing compound includes at least one of oxalic acid and ammonium oxalate;

[0084] Mix silver oxalate with an organic amine solution, and add a second auxiliary agent thereto to obtain an impregnation solution; let the impregnation solution stand for stabilization, and maintain the temperature of the impregnation solution (impregnation solution temperature); under normal pressure or vacuum conditions, impregnate 500 g of the carrier with the impregnation solution, and then perform drying and activation treatments in sequence to obtain the catalyst; wherein the organic amine solution contains at least one of ethylenediamine, ethanolamine, and 1,3-propanediamine, the stabilization time is 0.5 h - 1 h; the impregnation solution temperature is 20°C - 40°C; the second auxiliary agent includes a mixture of compounds formed by elements of alkali metals, alkaline earth metals, and transition metals, the addition amount of alkali metal elements is 0.01 - 0.05% of the mass of the impregnation solution, that is, 100 ppm - 500 ppm; the addition amount of alkaline earth metal elements is 0.01 - 0.09% of the mass of the impregnation solution, that is, 100 ppm - 900 ppm; the addition amount of transition metal elements is 0.04% - 0.05% of the mass of the impregnation solution, that is, 400 ppm - 500 ppm; the activation treatment process is to treat in an air stream at 150°C - 500°C or a steam-air stream with a water content of 1% - 100% for 2 - 30 minutes to obtain the catalyst, and the activation treatment conditions are: temperature 150°C - 500°C.

[0085] The specific conditions for preparing the catalysts using the carriers of Examples 1-4 and Comparative Examples 1-6 are shown in Tables 3 and 4, and the prepared catalysts were evaluated using the catalyst evaluation method.

[0086] Characterize the physical parameters and performance of the carriers and catalysts of the above Examples 1-4 and Comparative Examples 1-6. The test methods are as follows:

[0087] 1. Specific surface area of the carrier:

[0088] Determined using the ASAP 2020 instrument of Micromeritics, USA and the method in Standard GB / T19587-2004;

[0089] 2. Pore structure of the carrier:

[0090] Pore structure characterization includes pore size distribution, pore volume and porosity. The equipment used is the AutoPore9500 mercury intrusion porosimeter of Micromeritics, USA, and the test method refers to GB / T 21650.1-2008;

[0091] 3. Tortuosity factor of the carrier:

[0092] Determined by the SPSR dynamic method. The measurement temperature is 40°C, the tracer is N2, and only δav calculated according to the average pore diameter is taken as the value of the tortuosity factor. References: Gao Chong, Zhu Ying, Li Shusen, Pan Yinzhen, Zhu Bingchen. Dynamic method for determining the tortuosity factor of silver catalyst for ethylene oxidation to ethylene oxide [J]. Journal of Jilin Institute of Chemical Technology, 1997(03):8-13;

[0093] 4. Catalyst evaluation method

[0094] The catalysts in Examples 1-4 and Comparative Examples 1-6 were used to catalytically convert ethylene respectively. Specifically, it was carried out in a reaction device. The reaction device includes a gas mixing storage tank, a mass flow meter, a pressure sensor, a reactor, and a back pressure valve. Among them, the gas mixing storage tank, the mass flow meter, and the reactor are connected in sequence. The pressure of the reactor is adjusted by the back pressure valve and the pressure sensor. The reactor consists of a stainless steel tube with a diameter of 12 mm, a thermocouple sleeve with an inner diameter of 2 mm and an electric heater; the reaction process includes: putting 5 grams of crushed catalyst particles into the reactor, adjusting the reaction raw materials in the gas mixing storage tank according to the reaction conditions, then controlling the flow rate through the mass flow meter, and then introducing it into the reactor for reaction; among them, the bottom of the catalyst particles is supported by quartz wool; the reaction raw materials are 30 mol% ethylene, 8 mol% oxygen, 3 mol% CO2, N2 as the balance gas, and chloroethane is 4 ppm - 6 ppm; the reaction conditions are: space velocity 5000 h -1, the pressure was 1.60 Mpa; the temperature was 220 °C, and the time was 200 h; finally, the tail gas after the reaction was passed through an on-line pipeline to an on-line magnetic fan type mass spectrometer for analysis, and the ethylene content, ethylene oxide content, and carbon dioxide content in the reaction tail gas were obtained respectively. The results of ethylene conversion and ethylene oxide selectivity were obtained based on the analysis data. The calculation methods of ethylene conversion and ethylene oxide selectivity are as follows:

[0095] Ethylene conversion rate (%) = 100% - mol% of ethylene content in the reaction tail gas / mol% of ethylene content in the reaction raw material; Ethylene oxide selectivity (%) = 2 × (mol% of ethylene oxide content in the reaction tail gas - mol% of ethylene oxide content in the reaction raw material) / [2 × (mol% of ethylene oxide content in the reaction tail gas - mol% of ethylene oxide content in the reaction raw material) + (mol% of carbon dioxide content in the reaction tail gas - mol% of carbon dioxide content in the reaction raw material)];

[0096] The raw material compositions of the pore-forming agents in Examples 1-4 are shown in Table 1:

[0097] Table 1:

[0098]

[0099] The characterization results of the physical parameters of the carriers in Examples 1-4 and Comparative Examples 1-6 are shown in Table 2:

[0100] Number <![CDATA[Specific surface area (m 2 / g)]]> Pore volume (mL / g) Average pore diameter (nm) δav Support A 1.122 0.6327 2107.85 2.0401 Support B 1.142 0.6272 2160.01 1.9557 Support C 1.157 0.6401 2239.09 2.0135 Support D 1.081 0.6706 2317.92 2.1169 Comparative support E 1.923 0.5633 1219.56 2.2402 Comparative support F 1.814 0.5726 1301.15 2.2247 Comparative support G 1.722 0.5819 1352.19 2.2504 Comparative support H 1.619 0.5930 1381.96 2.3087 Comparative support I 2.218 0.4035 851.47 2.9085 Comparative support J 2.013 0.4797 962.06 2.7698

[0101] The conditions for preparing the catalysts using the carriers in Examples 1-4 and Comparative Examples 1-6 and the evaluation results are shown in Tables 3 and 4:

[0102] Table 3

[0103]

[0104] Table 4

[0105]

[0106] According to Tables 1-4, compared with the carriers of the comparative examples, the α-alumina carrier prepared by the preparation method provided by the present invention has a lower specific surface area, a larger pore volume and average pore diameter, and a low tortuosity factor. When the α-alumina carrier provided by the present invention is used as the carrier of the silver-loaded catalyst, the catalyst can promote the ethylene conversion rate to reach more than 9.0%, and the selectivity of ethylene oxide to reach more than 88.5%. This shows that the silver-loaded α-alumina-based catalyst provided by the present invention can reduce deep oxidation and improve the selectivity of ethylene oxide products.

[0107] The preferred specific embodiments of the present invention and experimental verification have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field according to the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A method for preparing an α-aluminum oxide support, characterized in that, It includes the following steps: (1) Mix a silicon-modified fiber material, hydrated alumina, a first auxiliary agent, and a fluorine-containing inorganic salt to obtain a mixture; the mass components of each component are: 1000 parts of hydrated alumina, 1-3 parts of the first auxiliary agent, 15-35 parts of the silicon-modified fiber material, and 10-30 parts of the fluorine-containing inorganic salt. The first auxiliary agent includes a compound of at least one element in Groups IIA, IVA, VIIA, IIB, IIIB, and IVB of the periodic table; (2) Mix the mixture obtained in step (1), a binder, an extrusion aid, and water, then carry out a shaping process, and after drying and calcination, obtain an α-alumina support; the mass components of the mixture, the binder, and the extrusion aid are: 1000 parts of the mixture, 50-200 parts of the binder, and 5-20 parts of the extrusion aid. A mullite phase with an element composition of Al-Si-O is formed on the inner surface of the pores of the prepared α-alumina support, and the treatment temperature of the calcination is 1200°C - 1400°C; The preparation process of the silicon-modified fiber material includes: Soak the vegetable cellulose material in an alcohol solution for more than 12 hours, and after solid-liquid separation, obtain a first solid and a first liquid respectively; dry the first solid at 100°C - 120°C for 4 - 8 hours to obtain the dried first solid; the mass ratio of the vegetable cellulose material to the alcohol solution is 1:2 - 10; Add an amine solution to the first liquid, adjust the pH to 7.5 - 10, and then add a silicate ester to make a silica sol containing lignin; the mass ratio of the silicate ester to the alcohol solution is 1:10 - 200; Mix the dried first solid with the silica sol containing lignin, and then dry at 60°C - 120°C for more than 12 hours to obtain the silicon-modified fiber material.

2. The preparation method according to claim 1, characterized in that, The hydrated alumina includes at least one of boehmite, pseudoboehmite, and gibbsite; and / or, The first auxiliary agent includes a compound of at least one element among Ca, Sr, Ba, Si, Zn, Zr, Y, and F; and / or, The fluorine-containing inorganic salt includes at least one of ammonium fluoride and aluminum fluoride; and / or, The extrusion aid includes at least one of white oil, paraffin wax, petrolatum, stearic acid, and sesbania powder; and / or, The binder includes at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, and citric acid; and / or, The mass of the binder accounts for 20% - 50% of the sum of the mass of the binder and the mass of water; and / or, The conditions of the drying treatment: the temperature is 100°C - 200°C, and the time is 2 - 12 hours; and / or, The time of the calcination treatment is 5 - 8 hours; and / or, In step (2), through the above-mentioned mixed molding, the formed product is a granular product, and the granular product includes at least one of Raschig ring-shaped particles, cylindrical particles without holes in the middle, and cylindrical particles with a porous structure. The Raschig ring-shaped particles satisfy the following conditions: the outer diameter is 5 mm - 10 mm, the particle length is 5 mm - 10 mm, and the middle hole diameter is 1.5 mm - 4.5 mm.

3. The preparation method according to claim 1 or 2, characterized in that, The alcohol solution includes at least one of methanol, ethanol, ethylene glycol, and propanol; and / or The mass concentration of the alcohol compound in the alcohol solution is 10% - 90%; and / or, The amine solution includes ammonia water and / or organic amine, and the organic amine includes at least one of ethylamine, ethylenediamine, ethanolamine, and n-butylamine; and / or, The mass concentration of the amine compound in the amine solution is 3% - 10%; and / or, The silicate ester includes at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

4. An α-aluminum oxide carrier, characterized in that, Prepared by the preparation method according to any one of claims 1 - 3.

5. A preparation method of a silver-loaded α-alumina-based catalyst, characterized in that, Including the following steps: An α-aluminum oxide carrier is prepared by the preparation method according to any one of claims 1 - 3; The α-aluminum oxide carrier is impregnated with an impregnating solution containing a silver source to obtain a silver-loaded α-aluminum oxide-based catalyst.

6. The preparation method according to claim 5, characterized in that, The silver source includes silver oxalate, and the impregnating solution is prepared according to the following process: dissolving the silver oxalate in an organic amine solution and adding a second auxiliary agent thereto to obtain the impregnating solution; wherein, the second auxiliary agent includes a compound formed by at least one element of alkali metal, alkaline earth metal, and transition metal.

7. A catalyst of a silver-loaded α-alumina-based catalyst, characterized in that, Including a carrier and a silver component supported on the carrier, and the carrier includes the α-aluminum oxide carrier according to claim 6.

8. A catalyst of a silver-loaded α-alumina-based catalyst, characterized in that, Prepared according to the following preparation process: Dissolve silver oxalate in an organic amine solution and add a second auxiliary agent thereto to obtain an impregnating solution; wherein, the second auxiliary agent includes a compound formed by at least one element of alkali metal, alkaline earth metal, and transition metal; The α-aluminum oxide carrier according to claim 6 is impregnated with the impregnating solution to obtain a silver-loaded α-aluminum oxide-based catalyst.

9. A method for preparing ethylene oxide, characterized in that, Including: The ethylene raw material is subjected to an epoxidation reaction under the action of a catalyst to obtain ethylene oxide, wherein the catalyst includes a silver-loaded α-aluminum oxide-based catalyst prepared by the preparation method according to claim 5 or 6 or the silver-loaded α-aluminum oxide-based catalyst according to claim 7 or 8.

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