阅读说明：本技术 α-氧化铝载体及乙烯环氧化用银催化剂和应用 (α -alumina carrier, silver catalyst for ethylene epoxidation and application ) 是由 任冬梅 林伟 王淑娟 代武军 汤之强 林强 韩红苓 李巍 曹淑媛 于 2019-01-16 设计创作，主要内容包括：本发明属于催化剂领域,涉及一种α-氧化铝载体及乙烯环氧化用银催化剂和应用。该α-氧化铝载体由包括以下步骤的方法制备得到：I)获得具有如下组成的固体混合物：粒度为10～30μm的α-A1<Sub>2</Sub>O<Sub>3</Sub>、粒度为1～5μm的α-A1<Sub>2</Sub>O<Sub>3</Sub>、可溶性淀粉、造孔剂、含硅化合物、含锆化合物；Ⅱ)向步骤I)的固体混合物中加入润滑剂；Ⅲ)向步骤Ⅱ)得到的混合物中加入水进行捏合、挤条成型,得到成型体；Ⅳ)将步骤Ⅲ)得到的成型体干燥、焙烧,制得所述α-A1<Sub>2</Sub>O<Sub>3</Sub>载体。与现有技术相比,由本发明的载体制成的银催化剂应用于乙烯氧化生产环氧乙烷的反应时,具有高活性和高选择性的优点。(The invention belongs to the field of catalysts, and relates to an α -alumina carrier, a silver catalyst for ethylene epoxidation and an application thereof.A α -alumina carrier is prepared by a method comprising the following steps of I) obtaining a solid mixture with the following components of particlesα -A1 with the degree of 10-30 mu m 2 O 3 α -A1 with the particle size of 1-5 mu m 2 O 3 Soluble starch, pore-forming agent, silicon-containing compound and zirconium-containing compound, II) adding lubricant into the solid mixture obtained in the step I), III) adding water into the mixture obtained in the step II) to knead and extrude the mixture into a molding, IV) drying and roasting the molding obtained in the step III) to obtain α -A1 2 O 3 And (3) a carrier. Compared with the prior art, the silver catalyst prepared by the carrier has the advantages of high activity and high selectivity when being applied to the reaction of producing ethylene oxide by oxidizing ethylene.)

1. An α -alumina carrier of a silver catalyst for ethylene epoxidation, wherein the α -alumina carrier is prepared by a method comprising the following steps:

I) a solid mixture having the following composition was obtained:

a) α -A1 with the particle size of 10-30 mu m and the content of 20-68 wt% of the total weight of the solid mixture₂O₃；

b) 8-55 wt% of α -A1 with the particle size of 1-5 mu m based on the total weight of the solid mixture₂O₃；

c) 5.0-14 wt% of soluble starch based on the total weight of the solid mixture;

d) 4.0-15 wt% of pore-forming agent based on the total weight of the solid mixture;

e) a silicon-containing compound in an amount of 0.05 to 0.5 wt% based on the total weight of the solid mixture;

f) a zirconium-containing compound in an amount of 0.1 to 1.5 wt% based on the total weight of the solid mixture;

II) adding a lubricant into the solid mixture obtained in the step I), wherein the amount of the lubricant is 1.0-6.0 wt% of the total weight of the solid mixture;

III) adding water into the mixture obtained in the step II) for kneading and extruding to form a formed body, wherein the amount of the water is 10-60 wt% of the total weight of the mixture obtained in the step II);

IV) drying and roasting the formed body obtained in the step III) to obtain α -A1₂O₃And (3) a carrier.

2.α -alumina carrier as claimed in claim 1, wherein the particle size is α -A1 of 10-30 μm based on the total weight of the solid mixture₂O₃The content of (b) is 25 to 65 wt%, preferably 30 to 60 wt%, and the particle size of α -A1 is 1 to 5 μm₂O₃The content of (b) is 10 to 50 wt%, preferably 15 to 43 wt%; the content of the soluble starch is 6.0-13 wt%, preferably 8-12 wt%.

3. The α -alumina carrier of claim 1, wherein the pore former is present in an amount of 5.0-14 wt.%, based on the total weight of the solid mixture, and is selected from at least one of petroleum coke, carbon powder, and graphite.

4. The α -alumina carrier according to claim 1, wherein the Si-containing compound is contained in an amount of 0.1-0.4 wt% based on the total weight of the solid mixture, and is selected from at least one of alkali metal silicate, alkaline earth metal silicate and silicon oxide.

5. The α -alumina carrier according to claim 1, wherein the zirconium-containing compound is present in an amount of 0.5 to 1.0 wt.% based on the total weight of the solid mixture, and is selected from at least one of a sulfate, a nitrate, a carbonate and an oxide of zirconium.

6. The α -alumina carrier as claimed in claim 1, wherein the lubricant is present in an amount of 1.5-5.0 wt% based on the total weight of the solid mixture, and is selected from at least one of vaseline, sesbania powder, and white oil.

7.α -alumina carrier according to claim 1, wherein the calcination temperature in step IV) is 1250 to 1450 ℃.

8.α -alumina carrier according to any one of claims 1 to 7, wherein α -A1 is in the carrier₂O₃The content of (A) is more than 90%; the crushing strength of the carrier is 45-130N, preferably 50-120N; the specific surface area is 1.0-2.0 m²A preferred concentration is 1.1 to 1.9m²(ii)/g; the pore volume is 0.35 to 0.52ml/g, preferably 0.37 to 0.51 ml/g.

9. A silver catalyst for the epoxidation of ethylene comprising:

a) the α -alumina support of any one of claims 1-8;

b) silver;

c) an alkali metal selected from at least one of lithium, sodium, potassium, rubidium, and cesium;

d) an alkaline earth metal selected from at least one of calcium, magnesium, strontium, and barium;

e) the rhenium promoter is selected from at least one of perrhenic acid, cesium perrhenate and ammonium perrhenate, and the rhenium co-promoter is selected from at least one of tungstic acid, cesium tungstate, molybdic acid and ammonium molybdate.

10. Use of an α -alumina carrier according to any one of claims 1 to 8 and/or a silver catalyst according to claim 9 in the production of ethylene oxide by epoxidation of ethylene.

Technical Field

The invention belongs to the field of catalysts, and relates to an α -alumina carrier for a silver catalyst for producing ethylene oxide by ethylene epoxidation, a silver catalyst prepared from the carrier, and applications of the α -alumina carrier and the silver catalyst in producing ethylene oxide by ethylene epoxidation.

Background

Ethylene epoxidation under the action of a silver catalyst produces mainly Ethylene Oxide (EO) and simultaneously produces carbon dioxide and water as side reactions, wherein activity, selectivity and stability are the main performance indexes of the silver catalyst. The activity refers to the reaction temperature required when the ethylene oxide production process reaches a certain reaction load, and the lower the reaction temperature is, the higher the activity of the catalyst is; selectivity refers to the ratio of moles of ethylene converted to ethylene oxide in the reaction to the total reacted moles of ethylene; stability is expressed as the rate of decline of activity and selectivity, with the smaller the rate of decline the better the stability of the catalyst.

Currently, there are three types of silver catalysts: the catalyst is a high-activity silver catalyst, has high activity and good stability, initial selectivity of 80-82% and service life of 2-5 years, and is suitable for all ethylene oxide/ethylene glycol (EO/EG) production devices; the second is high-selectivity silver catalyst, the highest selectivity of the catalyst reaches over 88 percent, but the catalyst requires CO in the reaction gas at the inlet of the reactor₂The concentration is below 1.0 percent, and the method is suitable for a newly-built EO/EG production device with relatively low space-time yield; thirdly, the catalyst is a silver catalyst with medium selectivity (the activity and the selectivity of the silver catalyst are between the activity and the selectivity of the silver catalyst), the selectivity of the catalyst can reach 83-85%, and the CO in the reaction gas at the inlet of the reactor is required to be in the range of₂The concentration is below 3%. The selectivity of different catalysts can be determined according to CO in the reaction gas₂The concentration and the outlet EO concentration are correspondingly adjusted, and in recent years, due to the requirements of energy consumption and environmental protection, the high-selectivity silver catalyst and the medium-selectivity silver catalyst are widely applied to industrial production and replace the original high-activity silver catalyst.

The performance of the silver catalyst is not only important in relation to the composition and preparation method of the catalyst, but also important in relation to the performance of the carrier used by the catalyst and the preparation method, namely α -Al₂O₃As for the carrier as the main component, the carrier physical properties include compressive strength, porosity, specific surface area and pore distribution, etc., and a good catalyst carrier has excellent compressive strength, porosity and specific surface area. The higher porosity can reduce the diffusion resistance of reactants and product gas under reaction conditions; the specific surface of the carrier is required to have the lowest value so as to ensure that the catalytic active component can be uniformly loaded on the carrier; the crush strength is a measure of the physical integrity of the support and is critical to the ability of the catalyst to withstand the harsher operating conditions and to ensure a longer service life. The carrier has better specific surface and porosity, and the compressive strength can be reduced; on the contrary, high compressive strength, which reduces the specific surface area and porosityThe balance between different physical properties is very important for the carrier.

US5384302 uses α -Al of two different particle sizes₂O₃And trihydrate alumina as raw materials, and titanium-containing auxiliary agent, pore-forming agent, ceramic binder and the like are added to prepare a carrier, and the carrier has better compressive strength and porosity after being calcined at 1500 ℃, so that the catalyst prepared from the carrier has better performance; US7060651 describes a high-silicon carrier, the content of silicon oxide is above 70%, the specific surface is 0.5-3.0m²The catalyst is prepared by using α -alumina with different particle sizes as raw material, adding zirconium, titanium and silicon-containing auxiliary agent, roasting at 1400-1550 ℃, and then the specific surface of the carrier is 1.3-5.0 m²The carrier is prepared by roasting α -alumina trihydrate with different particle sizes and certain proportions of pseudo-monohydrate alumina, pore-forming agent, fluxing agent, mineralizing agent, auxiliary agent and the like at the high temperature of 1300-1500 ℃ and has high selectivity by using 0.25-0.8 ml/g of pore volume, 0.1-10 mu m pores account for more than 80% of the total pore volume and 0.8-2 mu m average pore diameter, CN1217233A illustrates that the carrier is prepared by directly mixing 50-500 meshes of alumina trihydrate α -alumina trihydrate with certain proportions of pseudo-monohydrate alumina, fluxing agent, mineralizing agent, auxiliary agent and the like at the high temperature of 1250-1550 ℃ without adding pore-forming agent in the carrier preparation process, CN103372466A illustrates that different proportions of alumina trihydrate α -alumina, pseudo-monohydrate alumina monohydrate, mineralizing agent, auxiliary agent of alkaline earth metal compound and combustible lubricating material are uniformly mixed, kneaded, extruded into strips, molded and calcined at the high temperature to prepare the carrier, the mineralizing agent can reduce the crystal transformation temperature of alumina into wafers with the cross-phase distribution of more than α wt% (the surface area of alumina and the surface area of the carrier is smaller than 38790% of alumina, and the surface area of the wafer phase of alumina with the cross-phase distribution of alumina (387) prepared by using the method of alumina with the cross-phase of alumina with the low alumina phase distribution of alumina phase of the cross-phase of alumina with the low alumina phase distribution of the cross-phase (Dry-mixing a bulk pore forming agent and a water-soluble titanium compound, adding water, extruding, forming, drying and roasting at 1150-1600 ℃ to prepare a carrier, wherein the pore volume of the carrier is 0.2-0.8 ml/g, and more preferably 0.25-0.6 ml/g; the specific surface area is 0.4 to 4.0m²A concentration of 0.6 to 1.5 ml/g; the crush strength is greater than 8 pounds, more preferably greater than 10 pounds.

Although the above patent documents adopt various methods to improve the alumina carrier, which brings about different improvements to the activity and selectivity of the catalyst, with the large-scale industrial application of the silver catalyst with medium and high selectivity, the requirements of the silver catalyst and the carrier performance and application process thereof in the field are continuously increasing. Therefore, there is still a need to develop new alumina supports.

Disclosure of Invention

The inventor of the invention has conducted extensive and intensive research in the field of preparation of silver catalyst carriers, and found that α -alumina with different particle sizes is used as a raw material, and different binders are selected to influence carrier forming and physical properties.

The invention provides an α -alumina carrier of a silver catalyst for ethylene epoxidation, wherein the α -alumina carrier is prepared by a method comprising the following steps:

I) a solid mixture having the following composition was obtained:

a) α -A1 with the particle size of 10-30 mu m and the content of 20-68 wt% of the total weight of the solid mixture₂O₃；

b) 8-55 wt% of α -A with particle size of 1-5 μm based on the total weight of the solid mixture1₂O₃；

c) 5.0-14 wt% of soluble starch based on the total weight of the solid mixture;

d) 4.0-15 wt% of pore-forming agent based on the total weight of the solid mixture;

e) a silicon-containing compound in an amount of 0.05 to 0.5 wt% based on the total weight of the solid mixture;

f) a zirconium-containing compound in an amount of 0.1 to 1.5 wt% based on the total weight of the solid mixture;

II) adding a lubricant into the solid mixture obtained in the step I), wherein the amount of the lubricant is 1.0-6.0 wt% of the total weight of the solid mixture;

III) adding water into the mixture obtained in the step II) for kneading and extruding to form a formed body, wherein the amount of the water is 10-60 wt% of the total weight of the mixture obtained in the step II);

IV) drying and roasting the formed body obtained in the step III) to obtain α -A1₂O₃And (3) a carrier.

In the preparation method of the carrier, the α -A1 with the granularity of 10-30 mu m₂O₃Powder and α -A1 with the particle size of 1-5 mu m₂O₃The powder materials are mutually overlapped in the high-temperature roasting process to generate α -A1 with larger porosity and certain strength₂O₃The carrier, pore-forming agent burnt out in high-temperature roasting process to leave gap, soluble starch acting as binder under the action of water, at the same time burnt out in roasting process to leave gap, also acting as pore-forming agent, α -A1 with two different granularities₂O₃The carrier is matched and used in a specific dosage range, and the porosity of the prepared carrier can be increased by controlling the dosage of the soluble starch and the addition of the silicon-containing and zirconium-containing auxiliary agents, and meanwhile, the carrier has higher specific surface area.

According to the invention, preferably, the particle size is α -A1 with the particle size of 10-30 mu m based on the total weight of the solid mixture₂O₃The amount of the α -A1 is 25-65 wt%, preferably 30-60 wt%, based on the total weight of the solid mixture, the particle size is 1-5 mu m₂O₃The dosage is preferably 10 ^ e50 wt%, preferably 15 to 43 wt%. preferred ranges of α -A1₂O₃The catalyst with higher activity and selectivity can be obtained by matching the catalyst.

According to the invention, the amount of the soluble starch is too high to enable the powder to be extruded into strips, so that the amount of the soluble starch needs to be controlled, and the amount of the soluble starch is preferably 6.0-13 wt% and more preferably 8-12 wt% based on the total weight of the solid mixture.

According to the present invention, it is clear that the soluble starch has the function of pore-forming agent, but the term "pore-forming agent" as used in the method of the present invention refers to a component which is added separately and has the function of pore-forming, and the addition amount of the pore-forming agent does not include the amount of the soluble starch.

In the preparation method of the carrier, the pore-forming agent is usually an inflammable material, preferably at least one selected from petroleum coke, carbon powder and graphite, and the content of the pore-forming agent is preferably 5.0-14 wt% based on the total weight of the solid mixture.

In the preparation method of the carrier, water (preferably deionized water) is added to react with soluble starch to bond raw material components of the carrier together to form an extrudable material.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Various silver catalysts of the present invention were tested for their initial performance and stability using a laboratory reactor (hereinafter referred to as "micro-reactor") evaluation apparatus. The reactor used in the microreaction evaluation apparatus was a stainless steel tube having an inner diameter of 4mm, and the reactor was placed in a heating mantle. The filling volume of the catalyst is 1ml, and the lower part of the catalyst is provided with inert filler, so that a catalyst bed layer is positioned in a constant temperature area of the heating sleeve.

The assay conditions for activity and selectivity used in the present invention are as follows:

gas composition at the reactor inlet (mol%): ethylene (C)₂H₄) 28.0 +/-1.0; oxygen (O)₂) 7.4 plus or minus 0.2; carbon dioxide (CO)₂) < 1.0; cause steady qi (N)₂) And the rest; the inhibitor dichloroethane (approx.), Ethylene Oxide (EO) concentration, 2.50%. The reaction pressure is 2.1 MPa; space velocity, 4500/h; space-time yield, 221KgEO/m³Cat./h。

When the reaction conditions are stably achieved, the gas composition at the inlet and outlet of the reactor is continuously measured. The selectivity was calculated after volume shrinkage correction of the measurement results according to the following formula:

where Δ EO is the difference in the ethylene oxide concentration of the outlet gas and the inlet gas, and the average of more than 10 sets of test data was taken as the test result on the same day.

Support preparation comparative example 1

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g, less than 75 μm pseudo-monohydrate A1₂O₃40g of petroleum coke, 50g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 10g of vaseline and 100ml of dilute nitric acid (the weight ratio of nitric acid to water is 1: 3) are added to be kneaded into paste which can be extruded and molded, the paste is extruded and molded into a single-hole column with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole column is dried for more than 2 hours at 80 to 120 ℃ so as to reduce the free water content to be less than 10 percent, the carrier after the kneading and molding is put into a bell jar kiln and is heated from room temperature to 1350 ℃ for 33 hours, and the white α -A1 is obtained after the carrier is calcined for 5 hours₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Comparative example 2 Carrier preparation

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g, 100g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 30g of vaseline and 100ml of deionized water are added, and the starch binder is added too much, so that the powder cannot be extruded into strips and molded, and the data is shown in the following table 1.

Support preparation comparative example 3

Mixing α -A1 particles of 10-30 μm₂O₃450g of α -A1 with the particle size of 1-5 mu m₂O₃50g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, transferred into a kneader, added with 20g of vaseline and 100ml of deionized water and kneadedSynthesizing paste which can be extruded, extruding and forming into a single-hole column with 8.0mm of external diameter, 6.0mm of length and 2.0mm of internal diameter, drying at 80-120 deg.C for more than 2 hr to reduce the free water content to below 10%, placing the above-mentioned carrier into bell jar kiln, heating from room temperature to 1350 deg.C for 33 hr, calcining at 1350 deg.C for 5 hr to obtain white α -A1₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 1

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g, 30g of soluble starch, 50g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 20g of vaseline and 100ml of deionized water are added, the mixture is kneaded into an extrudable paste, the paste is extruded into a single-hole columnar object with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole columnar object is dried for more than 2 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent, the kneaded and molded carrier is put into a bell jar kiln, the temperature is increased from room temperature to 1350 ℃ after 33 hours, and the carrier is calcined for 5 hours at the temperature of 1350 ℃ to obtain white α -A1₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 2

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g of soluble starch, 50g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 20g of vaseline and 100ml of deionized water are added, the mixture is kneaded into an extrudable paste, the paste is extruded into a single-hole columnar object with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole columnar object is dried for more than 2 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent, the kneaded and molded carrier is put into a bell jar kiln, the temperature is increased from room temperature to 1350 ℃ after 33 hours, and the carrier is calcined for 5 hours at the temperature of 1350 ℃ to obtain white α -A1₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 3

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 20g of vaseline and 100ml of deionized water are added, the mixture is kneaded into an extrudable paste, the paste is extruded into a single-hole columnar object with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole columnar object is dried for more than 2 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent, the kneaded and molded carrier is put into a bell jar kiln, the temperature is increased from room temperature to 1350 ℃ after 33 hours, and the carrier is calcined for 5 hours at the temperature of 1350 ℃ to obtain white α -A₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 4

Mixing α -A1 particles of 10-30 μm₂O₃400g of α -A1 with the particle size of 1-5 mu m₂O₃100g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 20g of vaseline and 100ml of deionized water are added, the mixture is kneaded into an extrudable paste, the paste is extruded into a single-hole columnar object with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole columnar object is dried for more than 2 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent, the kneaded and molded carrier is put into a bell jar kiln, the temperature is increased from room temperature to 1350 ℃ after 33 hours, and the carrier is calcined for 5 hours at the temperature of 1350 ℃ to obtain white α -A₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 5

Mixing α -A1 particles of 10-30 μm₂O₃150g of α -A1 with the particle size of 1-5 mu m₂O₃350g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, transferred into a kneader, added with 20g of vaseline and 100ml of deionized water and kneaded into paste capable of being extruded and molded. Extruding and molding into a single-hole column with an outer diameter of 8.0mm, a length of 6.0mm and an inner diameter of 2.0mm at 80-120 deg.CDrying for more than 2 hr to reduce free water content to below 10%, placing the kneaded carrier into bell jar kiln, heating from room temperature to 1350 deg.C for 33 hr, and calcining at 1350 deg.C for 5 hr to obtain white α -A1₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Support preparation example 6

Mixing α -A1 particles of 10-30 μm₂O₃350g of α -A1 with the particle size of 1-5 mu m₂O₃150g of soluble starch, 90g of soluble starch, 75g of petroleum coke, 2.0g of calcium silicate and 5.0g of zirconium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, 20g of vaseline and 100ml of deionized water are added, the mixture is kneaded into an extrudable paste, the paste is extruded into a single-hole columnar object with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, the single-hole columnar object is dried for more than 2 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent, the kneaded and molded carrier is put into a bell jar kiln, the temperature is increased from room temperature to 1350 ℃ after 33 hours, and the carrier is calcined for 5 hours at the temperature of 1350 ℃ to obtain white α -A₂O₃And (3) a carrier. The measured physical properties of the support and the measured data of the pore structure distribution are shown in Table 1 below, respectively.

Catalyst preparation

Dissolving 98g of ethylenediamine in 150g of deionized water, slowly adding silver oxalate into the mixed solution under stirring, keeping the temperature below 40 ℃ to completely dissolve the silver oxalate, adding the silver oxalate in an amount which enables the silver content in the silver catalyst to be 21 percent (by weight) based on silver element, and adding 0.9g of cesium nitrate, 0.78g of strontium acetate, 0.44g of perrhenic acid and deionized water to enable the total mass of the solution to reach 500g to prepare impregnation liquid for later use.

250g of each of the carrier samples of comparative carrier preparation example 1 and carrier preparation examples 1 to 6 was taken, placed in a vacuum vessel, evacuated to 10mmHg or more, and the immersion liquid was introduced and held for 30 minutes to leach out an excess solution. Heating the impregnated carrier in 300 ℃ air flow for 3min, and cooling to obtain the silver catalysts DC1 and C1-C6.

The activity and selectivity of the catalyst samples were evaluated using a microreactor apparatus under the aforementioned process conditions, and the results of the evaluation are shown in table 2 below.

TABLE 1 Carrier Properties

TABLE 2 Properties of the catalysts

As can be seen from the data in Table 1, the carrier of the invention has higher specific surface area, crushing strength and pore volume, and all parameters of the carrier are balanced. The crushing strength of the carrier obtained in comparative example 3 was too low to be used for preparing a catalyst.

As can be seen from the data in table 2, the catalyst of the present invention has better activity and significantly improved selectivity. Adding the components in the preferred ranges results in a more balanced catalyst activity and selectivity.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.