CN116943653A - Catalyst for olefin epoxidation and preparation method and application thereof - Google Patents

Catalyst for olefin epoxidation and preparation method and application thereof Download PDF

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CN116943653A
CN116943653A CN202210412100.XA CN202210412100A CN116943653A CN 116943653 A CN116943653 A CN 116943653A CN 202210412100 A CN202210412100 A CN 202210412100A CN 116943653 A CN116943653 A CN 116943653A
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catalyst
silver
carrier
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containing solution
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李巍
李金兵
汤之强
代武军
李旻旭
王淑娟
任冬梅
林强
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Sinopec Beijing Chemical Research Institute Co ltd
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
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    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J23/00Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
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    • B01J23/54Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66Silver or gold
    • B01J23/68Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/688Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with manganese, technetium or rhenium
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    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02Impregnation, coating or precipitation
    • B01J37/0201Impregnation
    • B01J37/0203Impregnation the impregnation liquid containing organic compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02Impregnation, coating or precipitation
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    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02Impregnation, coating or precipitation
    • B01J37/0201Impregnation
    • B01J37/0213Preparation of the impregnating solution
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08Heat treatment
    • B01J37/082Decomposition and pyrolysis
    • B01J37/088Decomposition of a metal salt
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/344Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of electromagnetic wave energy
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    • C07DHETEROCYCLIC COMPOUNDS
    • C07D301/00Preparation of oxiranes
    • C07D301/02Synthesis of the oxirane ring
    • C07D301/03Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/04Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
    • C07D301/08Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase
    • C07D301/10Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase with catalysts containing silver or gold
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Abstract

The invention belongs to the technical field of catalysts, and discloses a catalyst for olefin epoxidation and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) Preparing a silver-containing solution comprising a silver compound precursor, an organic amine, water, and optionally an auxiliary agent; (2) Fully contacting the silver-containing solution with an alumina carrier, and leaching redundant solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution; (3) And (3) treating the carrier loaded with the silver-containing solution in infrared irradiation to obtain the catalyst. The catalyst for olefin epoxidation prepared by the method provided by the invention has the advantages that the silver content gradient inside and outside the catalyst is obviously reduced, the dispersibility of active centers is greatly improved, the agglomeration and blockage of nano particles are reduced, and the catalyst has excellent catalytic performance.

Description

Catalyst for olefin epoxidation and preparation method and application thereof
Technical Field
The invention relates to the technical field of catalysts, in particular to a preparation method of a catalyst for olefin epoxidation, the catalyst prepared by the preparation method and application thereof.
Background
Alkylene oxide is an important product and intermediate in petrochemical industry, and is widely used in various industries such as light industry, chemical industry, medicine, textile, food, etc. Among them, ethylene Oxide (EO) is an important ethylene derivative product, and is mainly used for producing Ethylene Glycol (EG), synthetic detergents, nonionic surfactants, anti-freezing agents, emulsifiers, ethylene glycol type products, and has wide and important applications in a variety of fields such as washing and dyeing, electronics, medicine, pesticides, textiles, automobiles, oil exploitation, refining, and the like.
At present, most of industrial devices for producing EO worldwide adopt an ethylene process, namely ethylene and oxygen are subjected to direct epoxidation reaction under the action of a silver catalyst to produce EO, and side reaction products are mostly CO 2 . In the prior art, silver catalysts are currently the only effective catalyst in this process and are the core of ethylene epoxidation reactions.
Silver catalysts used in commercial EO/EG units can be largely divided into three types: high activity silver catalysts, high selectivity silver catalysts, and medium selectivity silver catalysts. Wherein, the high-activity silver catalyst has the characteristics of high activity, good stability and selectivity of about 80 to 82 percent, and is relatively applicableCO at the reactor inlet 2 Traditional devices with higher concentrations (typically 5% -10%); the high selectivity silver catalysts are characterized by high selectivity, typically in excess of 88%, but for inlet CO 2 Is generally required to be less than 1% and is suitable for use in apparatuses having relatively low space-time yields; the medium selectivity silver catalyst is characterized by that its activity and selectivity are between those of above-mentioned two catalysts, and its selectivity can be up to about 85%, and its inlet CO is usually required 2 The concentration is below 3%.
The activity, selectivity and stability of the silver catalyst are main indexes for evaluating the performance of the silver catalyst. With the continuous increase of energy consumption and environmental protection requirements in recent years, new devices or modified devices increasingly start to use high-selectivity or medium-selectivity silver catalysts, and gradually replace the traditional high-activity silver catalysts. For decades of development of silver catalysts, modification of silver catalysts is mainly focused on modification of carriers and assistants, and research on preparation and activation processes is relatively few.
US4833261, US4761394 disclose silver catalysts with rhenium promoter addition, and disclose a prelude to the study of high selectivity silver catalysts. CN105233824a discloses a silver catalyst composed of Na, cs, ce, re, zr mixed auxiliary agent, and a regulating gas for promoting the stability of catalyst activity is introduced into the reaction system along with the reaction raw material in the reaction process, so as to improve the stability of the catalyst. CN112206798A discloses a silver catalyst based on a composite support of α -silicon carbide and α -alumina.
In the above patent documents, modification researches on carriers and auxiliaries are still mostly carried out, the selectivity is improved to a certain extent, but the basic preparation process is not changed, and the traditional preparation and activation processes are still adopted. For the traditional thermal activation process, the inventor researches and discovers that the rapid contact process of high-temperature gas and the catalyst easily causes the partial non-uniform heating of the catalyst, so that the composition difference between the inside and the outside is caused, the catalytic performance is obviously influenced, the comprehensive performance, especially the stability, of the silver catalyst is greatly influenced, and meanwhile, the process energy consumption is larger. Therefore, the development of a silver catalyst preparation method with higher efficiency and better comprehensive performance has important significance.
Disclosure of Invention
The invention aims at solving the problems that the prior preparation process of the ethylene epoxidation catalyst for preparing ethylene oxide has uneven heating, further leads to limited improvement of the comprehensive performance of the catalyst, and the like. The silver catalyst obtained in this way shows better catalyst comprehensive performance when being used for catalyzing ethylene gas phase direct oxidation to prepare ethylene oxide.
In order to achieve the above object, a first aspect of the present invention provides a method for producing a catalyst for olefin epoxidation, comprising:
(1) Preparing a silver-containing solution comprising a silver compound precursor, an organic amine, water, and optionally an auxiliary agent;
(2) Fully contacting the silver-containing solution with an alumina carrier, and leaching redundant solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution;
(3) And (3) treating the carrier loaded with the silver-containing solution in infrared irradiation to obtain the catalyst.
The second aspect of the present invention provides a catalyst for olefin epoxidation prepared by the above-described preparation method.
In a third aspect the present invention provides the use of the above catalyst in the direct oxidation of an olefin to produce an alkylene oxide, preferably ethylene.
The beneficial technical effects of the invention are as follows:
the catalyst for olefin epoxidation prepared by the method provided by the invention has the advantages that the silver content gradient inside and outside the catalyst is obviously reduced, the dispersibility of active centers is greatly improved, the agglomeration and blockage of nano particles are reduced, and the catalyst has excellent catalytic performance. Compared with the prior art, the catalyst has the advantages of further improving the activity, selectivity and stability of the catalyst, saving reaction raw materials, reducing reaction byproducts and prolonging the service life of the catalyst.
The preparation method of the invention greatly improves the preparation efficiency of the catalyst and reduces the production energy consumption of the catalyst.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein.
The first aspect of the present invention provides a process for producing a catalyst for olefin epoxidation, which comprises:
(1) Preparing a silver-containing solution comprising a silver compound precursor, an organic amine, water, and optionally an auxiliary agent;
(2) Fully contacting the silver-containing solution with an alumina carrier, and leaching redundant solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution;
(3) And (3) treating the carrier loaded with the silver-containing solution in infrared irradiation to obtain the catalyst.
In order to reduce and fix silver on the surface of the carrier, the carrier carrying the silver-containing solution needs to be activated. In the present invention, the activation takes place by means of infrared irradiation, which according to the present invention is preferably carried out in a furnace or tunnel installation fitted with an infrared radiator, preferably an electrically heated infrared radiator;
the infrared radiation is selected to have a wavelength of from 5 to 350 μm, preferably from 5 to 300 μm, more preferably from 200 to 300 μm; the temperature of the irradiated material is controlled to be 150-400 ℃, preferably 150-350 ℃; the infrared irradiation time is 1-50min, preferably 2-30min, and more preferably 2-5min.
According to the present invention, preferably, the infrared irradiation is performed in a flowing gas phase atmosphere, preferably at least one selected from the group consisting of an air stream, a nitrogen/oxygen mixed gas stream, a helium/oxygen mixed gas stream, and a nitrogen/hydrogen mixed gas stream, further preferably a nitrogen/oxygen mixed gas stream and/or a helium/oxygen mixed gas stream;
the flow rate of the gas phase atmosphere is 40 to 500ml/min, preferably 40 to 350ml/min, and more preferably 200 to 350ml/min.
According to the present invention, preferably, the silver compound precursor is selected from at least one of silver nitrate, silver carbonate, silver oxalate, and silver oxide;
the organic amine in the present invention may be selected from a variety of organic amine compounds as long as it is capable of forming a complex with a silver compound. According to the present invention, preferably, the organic amine is selected from at least one of ethylamine, ethylenediamine, n-propylamine, 1, 3-propylenediamine, n-butylamine, 1, 4-butanediamine, ethanolamine and propanolamine;
the promoter is selected from at least one of an alkali metal promoter, an alkaline earth metal promoter, a rhenium promoter and optionally a rhenium co-promoter.
In a preferred embodiment of the present invention, the alkali metal auxiliary may be one or more of soluble compounds of lithium, sodium, potassium, rubidium and cesium, for example, at least one of sulfate, nitrate, hydroxide, etc. of the above alkali metal element. The alkaline earth metal auxiliary agent may be one or more of soluble compounds of magnesium, calcium, strontium and barium, for example, at least one of sulfate, nitrate and acetate of the above alkaline earth metal element. The rhenium promoter may be one or more selected from rhenium oxides, ammonium rhenate, perrhenic acid and perrhenate. The rhenium co-promoter may be one or more selected from molybdenum compounds, tungsten compounds, chlorine compounds, manganese compounds, nickel compounds, phosphorus compounds and boron compounds.
According to the invention, the respective raw materials are preferably used in such amounts that the silver content in elemental form in the catalyst is 5-40wt%, preferably 10-30wt%, based on the total weight of the catalyst; the weight content of the auxiliary agent in the catalyst calculated by metal element is 0-5000ppm, preferably 100-3500ppm; the balance of alumina carrier;
wherein, in the auxiliary agent calculated by metal element, the weight content of alkali metal is preferably 10-1500ppm, more preferably 50-1200ppm; the alkaline earth metal content is preferably 5 to 1000ppm by weight, more preferably 20 to 800ppm by weight; the weight content of rhenium metal is preferably 10 to 1500ppm, more preferably 20 to 1000ppm; the co-promoter of rhenium is preferably present in an amount of from 0 to 1000ppm, more preferably from 10 to 500ppm, by weight as metal.
According to the present invention, the sufficient contact is preferably performed by any means of industrially producing a supported catalyst, such as impregnation, spraying or coating, preferably impregnation, and more preferably reduced pressure impregnation.
In a preferred embodiment of the invention, the silver-containing mixed solution is impregnated into the carrier under a vacuum of less than 10mmHg, the temperature of the mixed solution is preferably controlled to be 0-30 ℃, and the impregnation time is preferably 10-60 minutes. And then leaching the impregnating solution.
According to the present invention, preferably, the preparation method further comprises:
(4) Repeating the steps (2) and (3) on the obtained catalyst.
When the silver content in the catalyst needs to be increased, preparing a silver-containing solution with higher concentration, or carrying out the operation of the step (4) at least once according to the method, namely, soaking and activating the catalyst obtained after the activation of the step (3) again to achieve the aim of increasing the silver content.
In the present invention, the alumina carrier may be a carrier conventional in the field of alkylene oxide catalysts, and according to the present invention, preferably, the alumina carrier is a molded porous α -alumina carrier; the alumina support preferably has the following characteristics: the crush strength of the alumina support is 20 to 200N/grain, preferably 50 to 100N/grain; the specific surface area is 0.2-5m 2 Preferably 0.5-2m 2 /g; the water absorption is 30-80%, preferably 40-60%; the pore volume is 0.2-1.2ml/g, preferably 0.5-1.0ml/g.
In the present invention, the shape of the porous α -alumina support may take any form common in the art, such as spherical, annular, or cylindrical.
The second aspect of the present invention provides a catalyst for olefin epoxidation prepared by the above-described preparation method.
The catalyst for olefin epoxidation can directly catalyze and oxidize olefin to generate alkylene oxide, is particularly suitable for directly catalyzing and oxidizing ethylene to generate ethylene oxide, and has further improved catalytic performance.
As described above, the catalyst comprises a porous α -alumina support and the following components deposited thereon, based on the total weight of the catalyst:
i) 5-40wt%, preferably 10-30wt% of silver active component calculated as silver element;
ii) from 10 to 1500ppm, preferably from 50 to 1200ppm, of alkali metal auxiliary, calculated as alkali metal element;
iii) 5 to 1000ppm, preferably 20 to 800ppm, of an alkaline earth metal auxiliary in terms of alkaline earth metal element;
iv) 10 to 1500ppm, preferably 20 to 1000ppm, calculated on rhenium atom of a rhenium promoter;
v) optionally a rhenium co-promoter, if present, in a weight content of from 5 to 1000ppm, preferably from 10 to 500ppm, calculated as metal element;
the balance being carrier.
The catalysts of the present invention can be tested using the following performance test methods:
the catalyst of the present invention was tested for activity and selectivity using a laboratory fixed bed microreactor (hereinafter referred to as "microreactor") evaluation device. The micro-inverse evaluation device uses a stainless steel reaction tube with an inner diameter of 4mm, and the reaction tube is arranged in a heating sleeve. The catalyst loading volume was 1ml (12-18 mesh), and the lower portion had inert packing to allow the catalyst bed to be located in the constant temperature zone of the heating mantle.
The micro-inverse evaluation process conditions of the catalyst are as follows:
reaction gas composition: ethylene 30.0+ -2.0 mol%, oxygen 7.4+ -0.2 mol%, carbon dioxide<2.0mol% of dichloroethane with the balance being nitrogenA gas; the reaction pressure is 2.1MPa; airspeed 6000h -1 The method comprises the steps of carrying out a first treatment on the surface of the The target concentration of ethylene oxide in the reactor outlet tail gas was set at 2.5%.
In a third aspect the present invention provides the use of the above catalyst in the direct oxidation of an olefin to produce an alkylene oxide, preferably ethylene.
The invention is further illustrated by the following examples:
in all of the following examples and comparative examples, the supports used were shaped porous alpha-alumina supports produced industrially with the following characteristics: the crushing strength is 80N/grain, and the specific surface area is 1.20m 2 Per g, water absorption of 54% and pore volume of 0.8ml/g.
The infrared irradiation hearth used in all the following examples was a hearth equipped with an infrared radiator, which was an electrically heated infrared radiator.
In all of the following examples and comparative examples, the catalysts were tested for activity and selectivity using a laboratory fixed bed microreactor (hereinafter referred to as "microreactor") evaluation device. The micro-inverse evaluation device uses a stainless steel reaction tube with an inner diameter of 4mm, and the reaction tube is arranged in a heating sleeve. The catalyst loading volume was 1ml (12-18 mesh), and the lower portion had inert packing to allow the catalyst bed to be located in the constant temperature zone of the heating mantle.
In the micro-inverse evaluation process condition of the catalyst, the reaction gas composition: ethylene 30.0+ -2.0 mol%, oxygen 7.4+ -0.2 mol%, carbon dioxide<2.0mol percent of dichloroethane with proper amount and balance of nitrogen balance gas; the reaction pressure is 2.1MPa; airspeed 6000h -1 The method comprises the steps of carrying out a first treatment on the surface of the The target concentration of ethylene oxide in the reactor outlet tail gas was set at 2.5%.
After the above reaction conditions were stably reached, the gas composition at the inlet and outlet of the reactor was continuously measured. After the volume shrinkage correction is carried out on the measurement result, the selectivity is calculated according to the following formula:
where Δeo is the difference in the concentration of ethylene oxide in the outlet gas and the inlet gas ring, and the average of more than 10 sets of test data was taken as the test result on the same day.
The activity of the catalyst is judged by the reaction temperature, and the lower the reaction temperature is, the higher the activity is. The stability of the catalyst is judged through the reaction temperature rise, and the smaller the reaction temperature rise is, the better the stability is in the same evaluation time.
The relative silver element content of the inside and the outside of the catalyst is measured by EDX, and the lower the silver element content proportion R of the outside surface and the inside is, the smaller the difference of the internal and external silver content gradients is, and the more uniform the silver dispersion is.
Example 1
Mixing 20g of ethylenediamine, 10g of ethanolamine and 41.5g of deionized water to obtain a mixed solution, slowly adding 28.3g of silver nitrate into the mixed solution while stirring after the mixed solution is completely dissolved, and keeping the temperature of the solution at 0-15 ℃ to completely dissolve the silver nitrate. Then adding 0.045g cesium hydroxide, 0.063g strontium sulfate, 0.054g perrhenic acid and 0.020g ammonium molybdate to prepare a silver-containing impregnating solution for later use. 10g of alpha-alumina carrier is placed in a container, vacuumized to below 10mmHg, then the silver-containing impregnating solution is added into the container to submerge the carrier, and after the carrier is kept for 30 minutes, the excessive impregnating solution is drained, so that the surface of the carrier is free from residual liquid which can drip. Then activating the immersed material in an infrared irradiation hearth with flowing air, wherein the wavelength of infrared radiation is 280 mu m, the gas flow rate is 250ml/min, the material temperature is controlled at 300 ℃, and the activation time is 1 minute, so that the silver catalyst S1 is prepared.
Example 2
A catalyst was prepared according to the procedure of example 1, except that the "activation time 1 min" in example 1 was changed to "activation time 2 min", and the other conditions were the same as in example 1, to prepare catalyst S2.
Example 3
A catalyst was prepared according to the procedure of example 1, except that "flowing air" in example 1 was changed to "flowing helium/oxygen mixture", and the other conditions were the same as in example 1, to prepare a catalyst S3.
Example 4
Mixing 20g of ethylenediamine, 10g of ethanolamine and 41.5g of deionized water to obtain a mixed solution, slowly adding 28.3g of silver nitrate into the mixed solution while stirring after the mixed solution is completely dissolved, and keeping the temperature of the solution at 0-15 ℃ to completely dissolve the silver nitrate. Then adding 0.056g cesium hydroxide, 0.063g strontium sulfate, 0.067g perrhenic acid and 0.020g ammonium molybdate to prepare a silver-containing impregnating solution for later use. 10g of alpha-alumina carrier is placed in a container, vacuumized to below 10mmHg, then the silver-containing impregnating solution is added into the container to submerge the carrier, and after the carrier is kept for 30 minutes, the excessive impregnating solution is drained, so that the surface of the carrier is free from residual liquid which can drip. Then activating the immersed material in an infrared irradiation hearth with flowing air, wherein the wavelength of infrared radiation is 280 mu m, the gas flow rate is 250ml/min, the material temperature is controlled at 300 ℃, and the activation time is 1 min, so that the silver catalyst S4 is prepared.
Example 5
A catalyst was prepared according to the procedure of example 4, except that the "activation time 1 minute" in example 4 was changed to "activation time 2 minutes", and the other conditions were the same as in example 4, to prepare catalyst S5.
Example 6
A catalyst was prepared according to the procedure of example 4, except that the "material temperature control 300 ℃ in example 4 was changed to" material temperature control 320 ℃ in example 4 ", and the other conditions were the same as in example 4, to prepare catalyst S6.
Comparative example 1
Mixing 20g of ethylenediamine, 10g of ethanolamine and 41.5g of deionized water to obtain a mixed solution, slowly adding 28.3g of silver nitrate into the mixed solution while stirring after the mixed solution is completely dissolved, and keeping the temperature of the solution at 0-15 ℃ to completely dissolve the silver nitrate. Then adding 0.045g cesium hydroxide, 0.063g strontium sulfate, 0.054g perrhenic acid and 0.020g ammonium molybdate to prepare a silver-containing impregnating solution for later use. 10g of alpha-alumina carrier is placed in a container, vacuumized to below 10mmHg, then the silver-containing impregnating solution is added into the container to submerge the carrier, and after the carrier is kept for 30 minutes, the excessive impregnating solution is drained, so that the surface of the carrier is free from residual liquid which can drip. Then activating in air flow with the temperature of 300 ℃ for 1 minute, thus obtaining the silver catalyst DS1.
Comparative example 2
A catalyst was prepared according to the method of comparative example 1, except that the "activation time 1 minute" in comparative example 1 was changed to "activation time 5 minutes", and the other conditions were the same as in comparative example 1, to prepare catalyst DS2.
Comparative example 3
A catalyst was prepared according to the method of comparative example 1, except that the "temperature 300 ℃ in comparative example 1 was changed to" temperature 320 ℃ and the other conditions were the same as in comparative example 1, to prepare catalyst DS3.
Comparative example 4
Mixing 20g of ethylenediamine, 10g of ethanolamine and 41.5g of deionized water to obtain a mixed solution, slowly adding 28.3g of silver nitrate into the mixed solution while stirring after the mixed solution is completely dissolved, and keeping the temperature of the solution at 0-15 ℃ to completely dissolve the silver nitrate. Then adding 0.056g cesium hydroxide, 0.063g strontium sulfate, 0.067g perrhenic acid and 0.020g ammonium molybdate to prepare a silver-containing impregnating solution for later use. 10g of alpha-alumina carrier is placed in a container, vacuumized to below 10mmHg, then the silver-containing impregnating solution is added into the container to submerge the carrier, and after the carrier is kept for 30 minutes, the excessive impregnating solution is drained, so that the surface of the carrier is free from residual liquid which can drip. Then activating in air flow with the temperature of 300 ℃ for 5 minutes, thus obtaining the silver catalyst DS4.
Characterization and test case
The catalysts S1 to S6 of examples 1 to 6 and the catalysts DS1 to DS4 of comparative examples 1 to 4 were subjected to element content characterization and the external to internal relative content ratio R values were calculated and shown in Table 1 below; and the catalyst was used in the gas composition and space velocity of 6000h as described above -1 The results of the comparative evaluation under the condition of the reaction pressure of 2.1MPa for two months are shown in the following Table 1.
TABLE 1 micro-inverse evaluation results and characterization results of catalysts S1-S6 and comparative catalysts DS1-DS4
Sample of Average Selectivity (%) Initial reaction temperature (%) Reaction temperature rise (. Degree. C.) R
Catalyst S1 85.1 220.3 6.2 1.58
Catalyst S2 85.5 219.8 5.7 1.46
Catalyst S3 85.3 220.7 5.8 1.32
Catalyst S4 86.2 221.0 6.3 1.51
Catalyst S5 87.1 220.8 5.9 1.34
Catalyst S6 87.5 221.2 6.0 1.52
Comparative catalyst DS1 83.2 225.0 8.6 3.50
Comparative catalyst DS2 83.8 223.2 8.0 3.28
Comparative catalyst DS3 84.2 223.4 8.2 3.30
Comparative catalyst DS4 84.5 224.7 8.7 3.18
As can be seen from the above examples, comparative examples and Table 1, the silver catalyst prepared by the infrared irradiation preparation method has significantly improved active center dispersibility as compared with the silver catalyst prepared by the conventional preparation method, and at the same time, the activity, reaction selectivity and stability of the catalyst are improved and the catalytic performance is further improved when the catalyst is used for catalyzing ethylene gas phase direct oxidation to prepare ethylene oxide. In addition, the preparation method of the invention shortens the time required and improves the production efficiency.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or 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 various embodiments described.

Claims (10)

1. A method for preparing a catalyst for olefin epoxidation, characterized in that the method comprises:
(1) Preparing a silver-containing solution comprising a silver compound precursor, an organic amine, water, and optionally an auxiliary agent;
(2) Fully contacting the silver-containing solution with an alumina carrier, and leaching redundant solution on the surface of the carrier to obtain a carrier loaded with the silver-containing solution;
(3) And (3) treating the carrier loaded with the silver-containing solution in infrared irradiation to obtain the catalyst.
2. The preparation method according to claim 1, wherein the infrared irradiation is performed in a furnace or tunnel installation fitted with an infrared radiator, preferably an electrically heated infrared radiator;
the infrared radiation is selected to have a wavelength of from 5 to 350 μm, preferably from 5 to 300 μm, more preferably from 200 to 300 μm; the temperature of the irradiated material is controlled to be 150-400 ℃, preferably 150-350 ℃; the infrared irradiation time is 1-50min, preferably 2-30min, and more preferably 2-5min.
3. The preparation method according to claim 1, wherein the infrared irradiation is performed in a flowing gas phase atmosphere, preferably at least one selected from the group consisting of an air stream, a nitrogen/oxygen mixed gas stream, a helium/oxygen mixed gas stream and a nitrogen/hydrogen mixed gas stream, further preferably a nitrogen/oxygen mixed gas stream and/or a helium/oxygen mixed gas stream;
the flow rate of the gas phase atmosphere is 40 to 500ml/min, preferably 40 to 350ml/min, and more preferably 200 to 350ml/min.
4. The production method according to claim 1, wherein the silver compound precursor is at least one selected from the group consisting of silver nitrate, silver carbonate, silver oxalate, and silver oxide;
the organic amine is at least one selected from ethylamine, ethylenediamine, n-propylamine, 1, 3-propylenediamine, n-butylamine, 1, 4-butylenediamine, ethanolamine and propanolamine;
the promoter is selected from at least one of an alkali metal promoter, an alkaline earth metal promoter, a rhenium promoter and optionally a rhenium co-promoter.
5. The preparation method according to claim 1, wherein the amount of each raw material is such that the silver content in terms of element in the catalyst is 5 to 40wt%, preferably 10 to 30wt%, based on the total weight of the catalyst; the weight content of the auxiliary agent in the catalyst calculated by metal element is 0-5000ppm, preferably 100-3500ppm; the balance of alumina carrier;
wherein, in the auxiliary agent calculated by metal element, the weight content of alkali metal is preferably 10-1500ppm, more preferably 50-1200ppm; the alkaline earth metal content is preferably 5 to 1000ppm by weight, more preferably 20 to 800ppm by weight; the weight content of rhenium metal is preferably 10 to 1500ppm, more preferably 20 to 1000ppm; the co-promoter of rhenium is preferably present in an amount of from 0 to 1000ppm, more preferably from 10 to 500ppm, by weight as metal.
6. The method of preparation according to claim 1, wherein the sufficient contact is dipping, spraying or coating, preferably dipping, further preferably reduced pressure dipping.
7. The production method according to claim 1, wherein the production method further comprises:
(4) Repeating the steps (2) and (3) on the obtained catalyst.
8. The method of claim 1, wherein the alumina support is a shaped porous a-alumina support;
preferably, the alumina support has a crush strength of from 20 to 200N/grain, preferably from 50 to 100N/grain; the specific surface area is 0.2-5m 2 Preferably 0.5-2m 2 /g; the water absorption is 30-80%, preferably 40-60%; the pore volume is 0.2-1.2ml/g, preferably 0.5-1.0ml/g.
9. A catalyst for olefin epoxidation produced by the production process according to any one of claims 1 to 8.
10. Use of the catalyst according to claim 9 for the direct oxidation of olefins to alkylene oxides, preferably for the direct oxidation of ethylene to ethylene oxide.
CN202210412100.XA 2022-04-19 2022-04-19 Catalyst for olefin epoxidation and preparation method and application thereof Pending CN116943653A (en)

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