Catalyst for olefin oxidation and preparation method and application thereof

Abstract

The invention belongs to the field of catalysts, and discloses an olefin oxidation catalyst and a preparation method and application thereof.The preparation method comprises the steps that 1, a silver-containing compound, a sulfonyl compound and / or a sulfinyl compound, organic amine, water, optional ammonia water and optional auxiliaries are mixed, and a silver-containing solution is obtained; (2) fully contacting the silver-containing solution with an alumina carrier, and draining off excess solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution; and (3) roasting the carrier loaded with the silver-containing solution to obtain the catalyst. According to the catalyst prepared by the method disclosed by the invention, the size of the active metal is regulated and controlled, the dispersity is remarkably improved, and the surface electron cloud density is weakened, so that the catalyst has excellent catalytic performance. Compared with the prior art, the catalyst provided by the invention has higher stability and selectivity.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and more particularly, to a catalyst for olefin oxidation, a preparation method thereof, and an application thereof. Background Art

[0002] Epoxyalkanes are important products and intermediates in the petrochemical industry and are widely used in various industries such as light industry, chemical industry, medicine, textile, and food. Among them, ethylene oxide (EO) is an important ethylene-derived product, mainly used for the production of ethylene glycol (EG), synthetic detergents, nonionic surfactants, antifreeze agents, emulsifiers, ethylene glycol ethers, etc., and has extensive and important applications in many fields such as dyeing and finishing, electronics, medicine, pesticides, textiles, automobiles, oil exploration and refining.

[0003] At present, most of the industrial plants for producing EO in the world use the ethylene process, that is, ethylene and oxygen undergo a direct epoxidation reaction to produce EO under the action of a silver catalyst, and the by-products are mostly CO2. In existing research, the silver catalyst is currently the only effective catalyst in this process and is the core of the ethylene epoxidation reaction.

[0004] The silver catalysts used in industrial EO / EG plants can be mainly divided into three types: high-activity silver catalysts, high-selectivity silver catalysts, and medium-selectivity silver catalysts. Among them, the high-activity silver catalyst is characterized by high activity, good stability, and a selectivity of about 80% - 82%, and is more suitable for traditional plants with a relatively high CO2 concentration (generally 5% - 10%) at the reactor inlet; the high-selectivity silver catalyst is characterized by high selectivity, generally exceeding 88%, but has relatively high requirements for the CO2 concentration at the inlet, generally requiring less than 1%, and is suitable for plants with a relatively low space-time yield; the medium-selectivity silver catalyst is characterized by an activity and selectivity between the above two catalysts, and the selectivity can reach about 85%, and generally requires the CO2 concentration at the inlet to be below 3%.

[0005] The activity, selectivity, and stability of the silver catalyst are the main indicators for evaluating the performance of the silver catalyst. In recent years, with the continuous improvement of energy consumption and environmental protection requirements, newly built plants or retrofitted plants have increasingly started to use high-selectivity or medium-selectivity silver catalysts, gradually replacing the traditional high-activity silver catalysts. In the decades of the development of silver catalysts, the modification of silver catalysts has mainly focused on the modification of carriers and promoters, etc., and relatively few studies have been conducted on the preparation and activation process.

[0006] US4833261 and US4761394 disclose silver catalysts with rhenium promoters, opening the prelude to the research on highly selective silver catalysts. CN105233824A discloses a silver catalyst composed of mixed promoters such as Na, Cs, Ce, Re, and Zr, and a regulating gas that promotes the stability of the catalyst activity is introduced into the reaction system with the reaction raw materials during the reaction process to improve the stability of the catalyst. CN112206798A discloses a silver catalyst based on a composite support composed of α-silicon carbide and α-aluminum oxide. CN104220160A discloses a preparation method of a manganese-containing supported silver catalyst intermediate.

[0007] In the above patent documents, some have adjusted and changed the promoters of silver catalysts, and some have studied the preparation methods and reaction processes, but there is still much room for improvement in the comprehensive performance, especially the stability. Therefore, it is of great significance to develop an olefin epoxidation catalyst with high stability and high selectivity. Summary of the Invention

[0008] The object of the present invention is that the inventors have conducted extensive and in-depth research in the fields of supported heterogeneous catalysts and coordination chemistry, and found that sulfonyl or sulfinyl groups have amphiphilic coordination properties and strong coordination abilities, and can coordinate with multiple metal ions simultaneously to form S-M and / or O-M coordination bonds in the system. Therefore, introducing an appropriate amount of sulfonyl compounds and / or sulfinyl compounds into the silver catalyst can produce strong coordination bonding effects with a part of silver or other metal promoters, generate steric hindrance effects in the catalyst system, stabilize silver particles, inhibit the aggregation and growth of silver particles, thereby significantly improving the dispersion state and growth of silver particles, improving the stability of the catalyst, and slowing down the reaction temperature rise rate; and through the strong polarity of sulfonyl and / or sulfinyl groups, weakening the electron cloud density on the surface of the active metal of the catalyst, thereby reducing the adsorption strength of the catalyst for oxygen during the ethylene epoxidation reaction, and further improving the selectivity of the catalyst. The silver catalyst thus obtained has significantly improved stability and further enhanced selectivity when used for catalytic gas-phase direct oxidation of ethylene to ethylene oxide, greatly improving the comprehensive performance of the catalyst.

[0009] To achieve the above object, one aspect of the present invention provides a preparation method of a catalyst for olefin oxidation, the preparation method comprising:

[0010] (1) Mixing a silver compound, a sulfonyl compound and / or a sulfinyl compound, an organic amine, water, optionally ammonia water and optionally a promoter to obtain a silver-containing solution;

[0011] (2) Fully contacting the silver-containing solution with an alumina support, draining the excess solution on the surface of the support to obtain a support carrying the silver-containing solution;

[0012] (3) Calcinate the carrier loaded with the silver-containing solution to obtain a catalyst.

[0013] The second aspect of the present invention provides a catalyst prepared by the above preparation method.

[0014] The third aspect of the present invention provides the application of the above catalyst in the direct oxidation of olefins to produce alkylene oxides, preferably in the direct oxidation of ethylene to produce ethylene oxide.

[0015] The technical solution of the present invention has the following beneficial effects: For the olefin oxidation catalyst prepared by the method of the present invention, the size of the active metal is regulated, the dispersibility is significantly improved, and the surface electron cloud density is weakened, so that the catalyst has excellent catalytic performance. Compared with the prior art, the catalyst of the present invention has higher stability and selectivity, saves reaction raw materials, reduces reaction by-products, and prolongs the service life of the catalyst, and has significant application advantages.

[0016] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Description of the Drawings

[0017] The exemplary embodiments of the present invention will be described in more detail by combining with the drawings.

[0018] Figure 1a Shows a scanning electron microscope image of the catalyst according to Example 1 of the present invention.

[0019] Figure 1b Shows a scanning electron microscope image of the catalyst according to Comparative Example 1 of the present invention. Detailed Description of the Invention

[0020] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein.

[0021] One aspect of the present invention provides a preparation method of a catalyst for olefin oxidation, and the preparation method includes:

[0022] (1) Mix a silver-containing compound, a sulfonyl compound and / or a sulfinyl compound, an organic amine, water, optionally ammonia water and optionally an auxiliary agent to obtain a silver-containing solution;

[0023] (2) Make the silver-containing solution contact with an alumina carrier sufficiently, and drain the excess solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution;

[0024] (3) Calcinate the carrier carrying the silver-containing solution to obtain a catalyst.

[0025] In the present invention, preferably, step (1) is: mixing an organic amine, optionally ammonia water, a sulfonyl compound and / or a sulfinyl compound, and water to obtain a mixed solution, then adding a silver-containing compound to completely dissolve the silver-containing compound, and optionally adding an auxiliary agent finally to obtain a silver-containing solution.

[0026] According to the present invention, the function of introducing the sulfonyl compound and / or the sulfinyl compound is to coordinate with metal ions by using its amphiphilic coordination group and strong coordination ability to form S-M and / or O-M coordination bonds, thereby generating a steric effect and an electronic effect. Therefore, various compounds containing sulfonyl or sulfinyl can be used in the present invention. Preferably, the sulfonyl compound is selected from at least one of phenyl ethyl sulfone, diethyl sulfone, dimethyl sulfone, diphenyl sulfone, sulfolane, and 4,4-dihydroxy diphenyl sulfone;

[0027] The sulfinyl compound is selected from at least one of dimethyl sulfoxide, diethyl sulfoxide, benzyl phenyl sulfoxide, thionyl chloride, and diphenyl sulfoxide.

[0028] According to the present invention, preferably, in the silver-containing solution, the molar ratio of the sulfonyl compound and / or the sulfinyl compound to silver in terms of element is (0.1-2.0):1.0, preferably (0.2-1.2):1.0.

[0029] According to the present invention, preferably, the silver-containing compound is selected from at least one of silver nitrate, silver carbonate, silver oxalate, and silver oxide;

[0030] The organic amine in the present invention can be selected from various organic amine compounds as long as it can form a complex with the silver compound. Preferably, the organic amine is selected from at least one of ethylamine, ethylenediamine, n-propylamine, 1,3-propanediamine, n-butylamine, 1,4-butanediamine, ethanolamine, and propanolamine;

[0031] The auxiliary agent is selected from at least one of an alkali metal auxiliary agent, an alkaline earth metal auxiliary agent, and a rhenium auxiliary agent.

[0032] In the present invention, preferably, the alkali metal auxiliary agent can be one or more of soluble compounds of lithium, sodium, potassium, rubidium, and cesium, such as one or more of sulfates, nitrates, and hydroxides of the above alkali metal elements. The alkaline earth metal auxiliary agent can be one or more of soluble compounds of magnesium, calcium, strontium, and barium, such as one or more of sulfates, nitrates, and acetates of the above alkaline earth metal elements. The rhenium auxiliary agent can be selected from one or more of rhenium oxides, ammonium perrhenate, perrhenic acid, and perrhenates.

[0033] According to the present invention, preferably, the amounts of the respective raw materials are such that, based on the total weight of the catalyst, the silver content in the catalyst in terms of element is 5-40 wt%, preferably 12-35 wt%; the weight content of the promoter in the catalyst in terms of metal element is 0-4500 ppm, preferably 0-3000 ppm, more preferably 90-3000 ppm; the balance is the alumina support;

[0034] Among them, preferably, in the promoter in terms of metal element, the weight content of the alkali metal is 0-2000 ppm, preferably 0-1200 ppm, more preferably 50-1200 ppm; the weight content of the alkaline earth metal is 0-1200 ppm, preferably 0-800 ppm, more preferably 20-800 ppm; the weight content of the rhenium metal is 0-1300 ppm, preferably 0-1000 ppm, more preferably 20-1000 ppm.

[0035] The way of sufficient contact in the present invention can be any industrial preparation method of supported catalysts such as impregnation, spraying or coating; preferably impregnation.

[0036] In the present invention, preferably, the sufficient contact is carried out under vacuum conditions. As a preferred embodiment, under the condition that the vacuum degree is less than 10 mmHg, the support is impregnated in the silver-containing solution, and the temperature of the silver-containing solution is preferably controlled at 0-30 °C, and the impregnation time is preferably 10-60 minutes. Then the impregnation liquid is drained off.

[0037] In order to reduce and fix silver on the surface of the support, it is necessary to calcine and activate the support impregnated with the silver-containing solution above. Preferably, the calcination is carried out in a gas-phase fluid, and the gas-phase fluid is selected from at least one of an air stream, a nitrogen / oxygen mixed gas stream and a nitrogen / hydrogen mixed gas stream;

[0038] The temperature of the calcination is 150-400 °C, preferably 200-350 °C; the time of the calcination is 1-100 minutes, preferably 2-60 minutes.

[0039] According to the present invention, preferably, the preparation method further includes: (4) repeating steps (2) and (3) for the obtained catalyst.

[0040] When it is necessary to increase the silver content in the catalyst, a silver-containing solution with a higher concentration can be prepared, or according to the above step (4), the catalyst obtained after activation in step (3) is impregnated and activated again to achieve the purpose of increasing the supported silver content.

[0041] In the present invention, the alumina support can be a conventional support in the field of alkylene oxide catalysts. Preferably, the alumina support is a shaped α-alumina support;

[0042] The crushing strength of the carrier is 20 - 200 N / grain, preferably 50 - 180 N / grain; the specific surface area is 0.2 - 5 m 2 / g, preferably 0.5 - 3 m 2 / g; the water absorption rate is 30 - 80%, preferably 40 - 60%; the pore volume is 0.2 - 1.2 ml / g, preferably 0.5 - 1.0 ml / g.

[0043] The shaped α-alumina carrier can be in any form common in the art, such as spherical, annular or columnar.

[0044] The second aspect of the present invention provides a catalyst prepared by the above preparation method. This catalyst can directly catalytically oxidize olefins to produce alkylene oxides, is particularly suitable for directly catalytically oxidizing ethylene to produce ethylene oxide, and has further improved stability and selectivity.

[0045] The third aspect of the present invention provides the application of the above catalyst in the direct oxidation of olefins to produce alkylene oxides, preferably in the direct oxidation of ethylene to produce ethylene oxide.

[0046] The present invention will be further described below in conjunction with examples, but the scope of the present invention is not limited to these examples.

[0047] In the following examples and comparative examples,

[0048] The preparation method of the used α-alumina carrier is as follows: 180 g of boehmite, 120 g of pseudo-boehmite, 1 g of barium acetate, and 2 g of magnesium fluoride are loaded into a powder mixer and mixed evenly, and then transferred to a kneader, and 50 ml of dilute nitric acid (the volume ratio of nitric acid to water is 1:3) is added for kneading. After kneading evenly, it is transferred to an extrusion machine to be extruded into a columnar body. Then the columnar body is placed in a natural gas furnace and calcined at 1200 °C for 20 h, and finally cooled to room temperature to obtain the α-alumina carrier.

[0049] The crushing strength of the α-alumina carrier is 100 N / grain, the specific surface area is 1.20 m 2 / g, the water absorption rate is 54%, and the pore volume is 0.8 ml / g.

[0050] Among them, the crushing strength is measured by a DLⅡ type intelligent particle strength tester, the specific surface area is measured by the nitrogen physical adsorption BET method; the pore volume is measured by the mercury intrusion method. "Water absorption rate" refers to the volume of water saturatedly adsorbed by the carrier per unit mass, and the unit is mL / g. The measurement method is as follows: First, weigh a certain amount of carrier (assuming its mass is m1), take out the carrier after boiling in boiling water for 1 h and stand it upright on a wet gauze with moderate water content to remove the excess water on the surface of the carrier, and finally weigh the mass of the carrier after adsorbing water (assuming it is m2), and calculate the water absorption rate of the carrier according to the following formula.

[0051] Water absorption rate = (m2 - m1) / m1 / ρ 水

[0052] Where ρ 水 is the density of water at the measured temperature and atmospheric pressure.

[0053] In the following examples and comparative examples, the activity and selectivity of the catalyst were tested using a laboratory fixed-bed micro-reactor (hereinafter referred to as "micro-reactor") evaluation device. The micro-reactor evaluation device used a stainless steel reaction tube with an inner diameter of 4 mm, and the reaction tube was placed in a heating jacket. The catalyst loading volume was 1 ml (12 - 18 mesh), and there was an inert filler at the bottom to make the catalyst bed located in the constant temperature zone of the heating jacket.

[0054] In the micro-reactor evaluation process conditions of the catalyst, the reaction gas composition: ethylene 30.0 ± 2.0 mol%, oxygen 7.4 ± 0.2 mol%, carbon dioxide <2.0 mol%, a proper amount of dichloroethane, and the balance gas was nitrogen; the reaction pressure was 2.1 MPa; the space velocity was 6000 h -1 ; the target concentration of ethylene oxide in the tail gas at the reactor outlet was set to 2.5%.

[0055] After the above reaction conditions were stably reached, the gas compositions at the inlet and outlet of the reactor were continuously measured. After the measurement results were corrected for volume shrinkage, the selectivity was calculated according to the following formula:

[0056]

[0057] Where ΔEO is the concentration difference of ethylene oxide between the outlet gas and the inlet gas, and the average value of more than 10 groups of test data was taken as the test result of the day.

[0058] The activity of the catalyst was judged by the reaction temperature. The lower the reaction temperature, the higher the activity. The stability of the catalyst was judged by the reaction temperature rise. During the same evaluation time period, the smaller the reaction temperature rise, the better the stability.

[0059] The dispersion state of the active centers of the catalyst was observed by scanning electron microscopy (SEM).

[0060] Example 1

[0061] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 2.6 g of dimethyl sulfoxide and 40.8 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15 °C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina carrier and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the carrier. After keeping for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300 °C for 5 minutes to prepare the silver catalyst S1.

[0062] Example 2

[0063] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 5.2 g of dimethyl sulfoxide and 38.2 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15 °C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina carrier and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the carrier. After keeping for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300 °C for 5 minutes to prepare the silver catalyst S2.

[0064] Example 3

[0065] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 7.8 g of dimethyl sulfoxide and 35.6 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15 °C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina carrier and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the carrier. After keeping for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300 °C for 5 minutes to prepare the silver catalyst S3.

[0066] Example 4

[0067] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 5.2 g of dimethyl sulfoxide and 38.2 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15°C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.014 g of potassium hydroxide, 0.042 g of strontium sulfate and 0.054 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina support and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the support. After maintaining for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300°C for 5 minutes to prepare the silver catalyst S4.

[0068] Example 5

[0069] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 6.2 g of dimethyl sulfone and 37.2 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15°C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina support and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the support. After maintaining for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300°C for 5 minutes to prepare the silver catalyst S5.

[0070] Example 6

[0071] Mix 20 g of ethylenediamine, 8 g of ethanolamine, 7.9 g of thionyl chloride and 35.5 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, and keep the solution temperature at 0 - 15°C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina support and place it in a container. Evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the support. After maintaining for 30 minutes, drain off the excess impregnating solution. Then calcine in an air stream at 300°C for 5 minutes to prepare the silver catalyst S6.

[0072] Comparative Example 1

[0073] Mix 20 g of ethylenediamine, 8 g of ethanolamine and 43.4 g of deionized water to obtain a mixed solution. After complete dissolution, slowly add 28.3 g of silver nitrate to the mixed solution while stirring, keeping the solution temperature at 0 - 15 °C to completely dissolve the silver nitrate. Then add 0.067 g of cesium hydroxide, 0.028 g of potassium hydroxide, 0.084 g of strontium sulfate and 0.067 g of perrhenic acid to prepare a silver-containing impregnating solution for use. Take 10 g of α-alumina support and place it in a container, evacuate to below 10 mmHg, and then add the above silver-containing impregnating solution to submerge the support. After 30 minutes, drain the excess impregnating solution. Then calcine in an air stream at 300 °C for 5 minutes to prepare the silver catalyst DS1.

[0074] Test Example 1

[0075] The catalysts S1 and DS1 of Example 1 and Comparative Example 1 were observed by scanning electron microscopy (SEM). The morphology and distribution of the active centers of the catalysts are as follows Figure 1a and Figure 1b .

[0076] It can be seen from Figure 1a and Figure 1b that the dispersibility of the active centers of catalyst S1 is significantly better than that of catalyst DS1. The sizes of the active center particles are more uniform, and the particle aggregation situation is significantly improved. This shows that introducing sulfonyl compounds or sulfinyl compounds during the preparation process according to the content of the present invention can play a stabilizing role on silver particles, inhibit the aggregation and growth of silver particles, and thus significantly improve the dispersion state and growth situation of silver particles.

[0077] Test Example 2

[0078] The catalysts S1 - S6 of Example 1 - 6 and the catalyst DS1 of Comparative Example 1 were comparatively evaluated for one month under the gas composition and space velocity of 6000 h -1 and reaction pressure of 2.1 MPa as described above. The results are shown in Table 1 below.

[0079] Table 1 Micro-reaction evaluation results of catalysts S1 - S6 and comparative catalyst DS1

[0080] Sample Selectivity (%) Initial reaction temperature (°C) Monthly temperature rise (°C) Catalyst S1 86.5 220.5 6.3 Catalyst S2 87.6 220.8 5.7 Catalyst S3 87.8 221.0 5.6 Catalyst S4 87.4 220.4 5.8 Catalyst S5 87.2 220.7 6.8 Catalyst S6 85.5 221.2 7.5 Comparative catalyst DS1 82.6 222.4 10.8

[0081] It can be seen from Table 1 that by introducing sulfonyl compounds or sulfinyl compounds during the preparation of the catalyst, the reaction selectivity and stability of the prepared silver catalyst are significantly improved when used in the catalytic gas-phase direct oxidation of ethylene to ethylene oxide. At the same time, the reaction activity is also improved to a certain extent, and the comprehensive performance of the catalyst is significantly improved.

[0082] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. 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.

Claims

1. A method for preparing a catalyst for olefin oxidation, characterized in that, The preparation method comprises the following steps: (1) Mixing a silver-containing compound, a sulfonyl compound and / or a sulfinyl compound, an organic amine, water, optional ammonia water and an optional auxiliary agent to obtain a silver-containing solution; (2) Fully contacting the silver-containing solution with an alumina support, and draining the excess solution on the surface of the support to obtain a support carrying the silver-containing solution; (3) Calcining the support carrying the silver-containing solution to obtain a catalyst.

2. The preparation method according to claim 1, wherein, The sulfonyl compound is selected from at least one of phenyl ethyl sulfone, diethyl sulfone, dimethyl sulfone, diphenyl sulfone, sulfolane and 4,4-dihydroxy diphenyl sulfone; The sulfinyl compound is selected from at least one of dimethyl sulfoxide, diethyl sulfoxide, benzyl phenyl sulfoxide, thionyl chloride and diphenyl sulfoxide.

3. The preparation method according to claim 1, wherein, In the silver-containing solution, the molar ratio of the sulfonyl compound and / or the sulfinyl compound to silver in terms of element is (0.1-2.0):1.0, preferably (0.2-1.2):1.

0.

4. The preparation method according to claim 1, wherein The silver-containing compound is selected from at least one of silver nitrate, silver carbonate, silver oxalate and silver oxide; The organic amine is selected from at least one of ethylamine, ethylenediamine, n-propylamine, 1,3-propanediamine, n-butylamine, 1,4-butanediamine, ethanolamine and propanolamine; The auxiliary agent is selected from at least one of an alkali metal auxiliary agent, an alkaline earth metal auxiliary agent and a rhenium auxiliary agent.

5. The preparation method according to claim 1, wherein, The dosages of the raw materials are such that, based on the total weight of the catalyst, the silver content in the catalyst in terms of element is 5-40 wt%, preferably 12-35 wt%; the weight content of the auxiliary agent in the catalyst in terms of metal element is 0-4500 ppm, preferably 0-3000 ppm, more preferably 90-3000 ppm; the balance is the alumina support; Wherein, preferably, in the auxiliary agent in terms of metal element, the weight content of the alkali metal is 0-2000 ppm, preferably 0-1200 ppm, more preferably 50-1200 ppm; the weight content of the alkaline earth metal is 0-1200 ppm, preferably 0-800 ppm, more preferably 20-800 ppm; the weight content of the rhenium metal is 0-1300 ppm, preferably 0-1000 ppm, more preferably 20-1000 ppm.

6. The preparation method according to claim 1, wherein, The mode of the full contact is selected from impregnation, spraying or coating; preferably impregnation.

7. The preparation method according to claim 1, wherein, The calcination is carried out in a gaseous fluid, and the gaseous fluid is selected from at least one of an air stream, a nitrogen / oxygen mixed gas stream and a nitrogen / hydrogen mixed gas stream; The temperature of the calcination is 150-400 °C, preferably 200-350 °C; the time of the calcination is 1-100 minutes, preferably 2-60 minutes.

8. The preparation method according to claim 1, wherein, The preparation method further comprises: (4) Repeating steps (2) and (3) for the obtained catalyst.

9. According to the preparation method described in claim 1, wherein, The alumina support is an α-alumina support; The crushing strength of the carrier is 20 - 200 N / grain, preferably 50 - 180 N / grain; the specific surface area is 0.2 - 5 m 2 / g, preferably 0.5 - 3 m 2 / g; the water absorption rate is 30 - 80%, preferably 40 - 60%; the pore volume is 0.2 - 1.2 ml / g, preferably 0.5 - 1.0 ml / g.

10. A catalyst prepared by the preparation method according to any one of claims 1-9.

11. Use of the catalyst according to claim 10 in the direct oxidation of olefins to produce alkylene oxides, preferably in the direct oxidation of ethylene to produce ethylene oxide.

Images