CN111659470A - Silver catalyst for producing ethylene oxide by ethylene oxidation and preparation method and application thereof - Google Patents
Silver catalyst for producing ethylene oxide by ethylene oxidation and preparation method and application thereof Download PDFInfo
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- CN111659470A CN111659470A CN201910164441.8A CN201910164441A CN111659470A CN 111659470 A CN111659470 A CN 111659470A CN 201910164441 A CN201910164441 A CN 201910164441A CN 111659470 A CN111659470 A CN 111659470A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/26—Catalysts comprising hydrides, coordination complexes or organic compounds containing in addition, inorganic metal compounds not provided for in groups B01J31/02 - B01J31/24
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/02—Synthesis of the oxirane ring
- C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
- C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
- C07D301/08—Synthesis 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
- C07D301/10—Synthesis 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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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
- B01J2231/70—Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues
- B01J2231/72—Epoxidation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
The invention belongs to the field of catalysts, and relates to a silver catalyst for producing ethylene oxide by ethylene oxidation, and a preparation method and application thereof. The silver catalyst comprises: i. a porous alumina support; silver, a surfactant component and optionally at least one of the following components supported on the porous alumina support: an alkali metal assistant, an alkaline earth metal assistant, a rhenium assistant and a rhenium assistant; the surfactant component is a water-soluble amphoteric surfactant. The silver catalyst provided by the invention has stable performance and higher activity and selectivity, and is particularly suitable for the reaction of producing ethylene oxide by oxidizing ethylene.
Description
Technical Field
The invention belongs to the field of catalysts, and particularly relates to a silver catalyst for producing ethylene oxide by oxidizing ethylene, a preparation method of the silver catalyst for producing ethylene oxide by oxidizing ethylene, and application of the silver catalyst for producing ethylene oxide by oxidizing ethylene.
Background
Under the action of silver catalyst, ethylene is oxidized to produce ethylene oxide and side reaction to produce carbon dioxide, water, etc. with activity, selectivity and stability as the main performance indexes of silver catalyst. The activity is the reaction temperature required for the ethylene oxide production process to reach a certain reaction load, and the lower the reaction temperature, the higher the activity of the catalyst. By selectivity is meant the ratio of the moles of ethylene converted to ethylene oxide in the reaction to the total moles of ethylene reacted. The stability is expressed as the rate of decrease in activity and selectivity, and the smaller the rate of decrease, the better the stability of the catalyst. The silver catalyst with high activity, high selectivity and good stability is used in the process of producing ethylene oxide by oxidizing ethylene, so that the economic benefit can be greatly improved, and the preparation of the silver catalyst with high activity, high selectivity and good stability is the main direction of research on the silver catalyst. The performance of the silver catalyst is not only important in relation to the composition of the catalyst and the preparation method, but also important in relation to the performance of the carrier used in the catalyst and the preparation method.
The preparation method of the silver catalyst mainly comprises two processes of preparing a porous carrier (such as alumina) and applying an active component and an auxiliary agent to the carrier.
Wherein, the carrier needs to provide a certain surface loading active component, the active component is evenly dispersed on the carrier, the silver catalyst generally adopts alpha-alumina as the carrier, and the preparation method mainly comprises the following steps: adding a binder, various additives and the like into the raw materials of the alumina powder, mixing and kneading uniformly, then extruding and molding into blanks (Raschig rings, spherical particles, porous columns, saddles and the like) with different shapes, and finally sintering at high temperature to prepare the porous heat-resistant alpha-alumina carrier product. In the preparation process of the silver catalyst carrier, an auxiliary agent is often added to improve the performance of the carrier.
The impregnation activation method is generally selected by industry for the process of applying the active ingredients and the auxiliaries to the carrier. Firstly, silver salt, various auxiliary agents and organic amine are prepared into silver-ammonia impregnation solution with a certain concentration, and Ag ions and the organic amine are subjected to a complex reaction to generate silver-organic ammonia complex ions; then the carrier is put into the dipping solution for dipping for enough time, so that the silver-ammonia complex ions and various auxiliary agent ions are dipped on the surface of the carrier along with the solution; after leaching, the carrier is put into hot air (or special atmosphere) for activation, during the activation process, various silver-containing impregnation components on the surface of the carrier are heated and gradually decomposed, silver ions are reduced into simple substance silver, and particles of tens of nanometers to hundreds of nanometers are formed on the surface of the carrier, so that the finished product of the silver catalyst is obtained.
Each step in the silver catalyst preparation process affects the uniformity, distribution uniformity, and consequently the catalyst performance, of the silver particles in the final product. The conventional impregnation activation process for industrially preparing silver catalysts has limited improvement in the activity and selectivity of the catalysts. Therefore, development of a new silver catalyst and a process for preparing the same are required.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, the present inventors have conducted extensive and intensive studies in the field of silver catalysts and processes for preparing the same, and as a result, have found that the reactivity of silver catalysts can be improved to obtain significantly improved activity, selectivity and stability by adding a surfactant component to the silver catalysts.
In a first aspect, the present invention provides a silver catalyst for ethylene oxidation to ethylene oxide, the silver catalyst comprising:
i. a porous alumina support; and the number of the first and second groups,
silver, a surfactant component and optionally at least one of the following components supported on said porous alumina support: an alkali metal assistant, an alkaline earth metal assistant, a rhenium assistant and a rhenium assistant; the surfactant component is a water-soluble amphoteric surfactant.
In the present invention, the "water-soluble amphoteric surfactant" refers to an amphoteric surfactant capable of being dissolved in water, and its meaning and category are well known to those skilled in the art.
The molecular weight of the surfactant is not particularly limited in the present invention, and the molecular weight may range from 200 to several thousands, even tens of thousands, up to 2000 thousands.
According to the present invention, the surfactant component is preferably contained in an amount of 5 to 10000ppm, preferably 10 to 5000ppm, more preferably 15 to 1000ppm, and still more preferably 20 to 400ppm, based on the total weight of the silver catalyst. For example, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, 110ppm, 120ppm, 130ppm, 140ppm, 150ppm, 160ppm, 170ppm, 180ppm, 190ppm, 200ppm, 210ppm, 220ppm, 230ppm, 240ppm, 250ppm, 260ppm, 270ppm, 280ppm, 290ppm, 300ppm, 310ppm, 320ppm, 330ppm, 340ppm, 350ppm, 360ppm, 370ppm, 380ppm, 390ppm, 400 ppm.
In the present invention, ppm represents a mass concentration, and 1ppm is 1mg/kg (10)-6kg/kg)。
In the invention, the content of the surfactant component can be determined by analyzing the content of characteristic groups such as carboxyl, hydroxyl, amino, carbonyl, amide and the like in the catalyst by methods such as nuclear magnetism, infrared, ultraviolet, gel chromatography and the like. This method is well known to those skilled in the art and will not be described in detail herein.
The present invention is not particularly limited with respect to the specific type of surfactant, provided that the water solubility requirement is satisfied. The amphoteric surfactant is preferably at least one selected from betaine surfactants, amine oxide surfactants, zwitterionic Polyacrylamide (PAM), amino acid surfactants and amphoteric imidazoline surfactants; further preferably, the amphoteric surfactant is selected from at least one of dodecyl dimethyl sulfopropyl betaine, dodecyl ethoxy sulfobetaine, tetradecylamidopropyl hydroxypropyl sulfobetaine, phospholipide betaine, octadecyl dihydroxyethyl amine oxide, octadecyl amidopropyl amine oxide, zwitterionic polyacrylamide, lauryl oil and glycine.
The silver catalyst of the present invention may contain other components except the surfactant in an amount conventional in the art. In particular, the amount of the solvent to be used,
the silver content may be 1 to 35 wt%, preferably 5 to 30 wt%, calculated as silver element, based on the total weight of the silver catalyst.
The alkali metal promoter may be present in an amount of 5 to 2000ppm, preferably 10 to 1500ppm, in terms of alkali metal element, based on the total weight of the silver catalyst.
The content of the alkaline earth metal promoter may be 5 to 8000ppm, preferably 10 to 3000ppm, in terms of alkaline earth metal element, based on the total weight of the silver catalyst.
The rhenium promoter may be present in an amount of from 5 to 1500ppm, preferably from 10 to 1000ppm, based on the total weight of the silver catalyst, calculated as rhenium element.
The rhenium co-promoter content may be from 5 to 1000ppm, preferably from 10 to 500ppm, based on the rhenium co-promoter element, based on the total weight of the silver catalyst.
The invention is not particularly restricted with regard to the characteristics of the support used, and according to a preferred embodiment the porous alumina support has the characteristics α -A12O3The content is more than or equal to 85 percent, preferably α -A12O3The content is more than or equal to 90 percent; the crushing strength of the particles is more than or equal to 20N, preferably 30-150N; the specific surface area is 0.2-7.0m2A/g, preferably from 0.5 to 6.0m2A water absorption of not less than 30%, preferably not less than 40%,the pore volume is 0.35-0.85ml/g, preferably 0.40-0.8 ml/g.
According to a preferred embodiment of the present invention, the silver catalyst is prepared by a method comprising the steps of:
a. impregnating the porous alumina carrier with a silver-containing impregnating solution to obtain a solid-liquid mixture;
b. b, performing solid-liquid separation on the solid-liquid mixture obtained in the step a, and drying the obtained solid phase;
c. activating the dried solid phase obtained in the step b;
wherein, in any step a to c, a surfactant or a precursor thereof is added for treatment;
the silver-containing impregnating solution contains a silver compound, an organic amine, water and optionally at least one of the following components: alkali metal assistant, alkaline earth metal assistant, rhenium assistant and rhenium assistant.
According to the invention, the surfactant precursor is a substance which can obtain a corresponding surfactant after being added into a preparation process system. For example, when the surfactant is a polymer, the surfactant precursor may be a monomer of the polymer. For another example, the surfactant precursor may be a derivative of a surfactant.
According to the present invention, the treatment with the surfactant or its precursor is aimed at finally causing the surfactant to be supported on the surface of the porous alumina carrier. Therefore, the timing of adding the surfactant or its precursor and the specific treatment method are not particularly limited in the present invention. The surfactant or precursor thereof can be treated in a combined manner, namely, the surfactant or precursor thereof is directly added in the existing steps of the silver catalyst preparation process, or in a separate treatment manner, namely, the surfactant or precursor thereof is additionally treated on the objects of the steps. For the specific treatment method, as long as the surfactant or its precursor can contact with the carrier, the skilled person can select the specific contact method according to the actual situation, such as soaking and/or spraying, and the soaking and/or spraying time can be determined according to the needs, such as 10-60 minutes.
According to the present invention, the surfactant or precursor thereof may be directly added, or a solution containing the surfactant or precursor thereof may be used, depending on the timing of the addition of the surfactant or precursor thereof. The solution containing the surfactant or the precursor thereof comprises the surfactant or the precursor thereof and a solvent; the solvent is a good solvent capable of dissolving the surfactant, and is preferably at least one selected from the group consisting of water, ethanol, and acetone. The concentration of the surfactant or precursor thereof in the solution containing the surfactant or precursor thereof is not particularly limited, and the amount of the surfactant finally supported on the carrier is targeted. Preferably, the concentration of the surfactant or precursor thereof in the solution containing the surfactant or precursor thereof is 0.001 wt% to 10 wt%, preferably 0.002 wt% to 8 wt%, and more preferably 0.1 wt% to 5 wt%.
In one embodiment of the present invention, the surfactant or precursor thereof is treated by: adding the surfactant or a precursor thereof to the silver-containing impregnation liquid. In the present invention, the concentration of the surfactant or a precursor thereof in the silver-containing impregnation liquid is not particularly limited, and the amount of the surfactant finally supported on the carrier is targeted. Preferably, the concentration of the surfactant or the precursor thereof in the silver-containing impregnation liquid is 0.001 wt% to 10 wt%, more preferably 0.002 wt% to 8 wt%, and still more preferably 0.1 wt% to 5 wt%.
In one embodiment of the present invention, the surfactant or precursor thereof is treated by: in step a, the carrier is treated with a surfactant or precursor thereof before, during or after impregnation, and optionally dried after treatment with a surfactant or precursor thereof. Whether or not drying is performed depends on the process in which the surfactant or precursor thereof is specifically treated at which step. For example, for the surfactant or precursor thereof treatment prior to impregnation, drying after the treatment is required, specifically, the carrier is immersed in a solution containing the surfactant or precursor thereof, then leached to remove excess liquid, and then dried for use. The drying conditions are, for example, drying at 100-150 ℃ for 0.1-48 h.
In one embodiment of the present invention, the surfactant or precursor thereof is treated by: in step b, the step of treating with a surfactant or a precursor thereof is performed before or after drying, and optionally, drying is performed after treating with a surfactant or a precursor thereof. Whether or not drying is performed depends on the process in which the surfactant or precursor thereof is specifically treated at which step. For example, after the solid phase is dried, it is preferable to perform drying again by treating the solid phase with a surfactant or a precursor thereof. In step b, all drying temperatures can be selected to be between 20 ℃ and 100 ℃, and the drying time can be selected to be 1-96 hours. After drying, the water content of the impregnated solid phase is preferably less than 10%.
In one embodiment of the present invention, the surfactant or precursor thereof is treated by: in step c, a step of treating with a surfactant or a precursor thereof is performed before or after activation, and drying is performed after the treatment with the surfactant or the precursor thereof. For example, the activated solid phase is soaked in a solution containing a surfactant or a precursor thereof, and then dried, for example, at 100-150 ℃ for 0.1-48 h. The activation according to the invention can be carried out using conditions customary in the art, for example in air or inert gas. For example, the dried solid phase may be activated in a stream of flowing air or inert gas such as nitrogen, argon, etc. at 180-700 deg.C, preferably 200-500 deg.C for a period of typically at least 2 minutes, such as 2-120 minutes, preferably 2-60 minutes. To ensure a high activity of the catalyst, the activation temperature is preferably not higher than 500 ℃.
In order to ensure a uniform and sufficient loading of the silver, according to the invention, the support is preferably pre-evacuated, typically to a vacuum of less than 10mmHg, prior to impregnation with the silver-containing impregnation solution.
According to the present invention, the silver compound may be any silver compound suitable for preparing a silver catalyst for ethylene oxide production. The present invention preferably uses at least one of silver oxide, silver nitrate and silver oxalate.
According to the present invention, the organic amine may be any organic amine compound suitable for preparing a silver catalyst, as long as the organic amine compound is capable of forming a silver amine complex with a silver compound. For the purposes of the present invention, preference is given to using pyridine, butylamine, ethylenediamine, 1, 3-propanediamine, ethanolamine or mixtures thereof, for example mixtures of ethylenediamine and ethanolamine.
According to the invention, the auxiliary agent of the active component silver comprises at least one of an alkali metal auxiliary agent, an alkaline earth metal auxiliary agent, a rhenium auxiliary agent and a synergistic agent of the rhenium auxiliary agent, and in the case of using the rhenium auxiliary agent, the synergistic agent of the rhenium auxiliary agent is preferably used.
According to the invention, the alkali metal promoter may be a compound of lithium, sodium, potassium, rubidium or cesium (such as nitrate, sulfate and hydroxide) or a mixture thereof, preferably at least one of cesium nitrate, lithium nitrate and potassium hydroxide.
The alkaline earth metal promoter may be at least one of compounds of magnesium, calcium, strontium and barium, such as at least one of oxides, oxalates, sulfates, acetates and nitrates of the alkaline earth metal elements, preferably a barium compound and/or a strontium compound, such as barium acetate and/or strontium acetate.
According to the present invention, the rhenium promoter may be an oxide, perrhenic acid, perrhenate, or mixtures thereof, preferably perrhenic acid and/or perrhenate, for example at least one of perrhenic acid, cesium perrhenate and ammonium perrhenate. The co-adjuvant of the rhenium adjuvant may be selected from at least one of a chromium compound, a molybdenum compound, a tungsten compound, and a boron compound.
A second aspect of the present invention provides a method for preparing the above silver catalyst, comprising the steps of:
a. impregnating the porous alumina carrier with a silver-containing impregnating solution to obtain a solid-liquid mixture;
b. b, performing solid-liquid separation on the solid-liquid mixture obtained in the step a, and drying the obtained solid phase;
c. activating the dried solid phase obtained in the step b;
wherein, in any step a to c, a surfactant or a precursor thereof is added for treatment;
the silver-containing impregnating solution contains a silver compound, an organic amine, water and optionally at least one of the following components: alkali metal assistant, alkaline earth metal assistant, rhenium assistant and rhenium assistant.
In the preparation method of the present invention, the components and the process steps are further defined as described above, and are not described herein again.
According to a specific embodiment of the present invention, the preparation method of the silver catalyst comprises the steps of: firstly, reacting a silver nitrate water solution with an ammonium oxalate or oxalic acid water solution to separate out a silver oxalate precipitate, filtering, washing with deionized water until no nitrate ions exist, and drying to obtain an oxalate compound. Then dissolving silver oxalate into aqueous solution of organic amine (such as pyridine, butylamine, ethylenediamine, 1, 3-propane diamine, ethanolamine or mixture thereof) and amphoteric surfactant, and adding various additives (if necessary) to prepare dipping solution; then using the obtained impregnation solution to impregnate the alpha-alumina carrier for 10-60 minutes under the condition of vacuum degree less than 10mmHg, leaching and drying, wherein the drying temperature can be selected from room temperature to 100 ℃, and the drying time can be selected from 1-96 hours; finally, the activation is carried out in air or inert gas at a temperature in the range of 200 ℃ and 500 ℃ for 1 to 120 minutes, preferably 2 to 60 minutes. In the above-mentioned step, silver oxide can be substituted for silver nitrate, and silver oxalate can be directly complexed with organic amine, and then used for impregnating carrier.
A third aspect of the invention provides the use of a silver catalyst in the epoxidation of ethylene to ethylene oxide. The use comprises subjecting ethylene to epoxidation in the presence of the silver catalyst described above.
The silver catalyst provided by the invention has stable performance and higher activity and selectivity, and is particularly suitable for the reaction of producing ethylene oxide by oxidizing ethylene.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
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.
Measurement of catalyst Performance
The performance of each silver catalyst of the present invention was measured by a laboratory microreactor (hereinafter referred to as "microreaction") evaluation device. The reactor used in the microreaction evaluation device was a stainless steel reaction tube having an inner diameter of 4mm, and the reaction tube 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 conditions for determining the activity and selectivity employed in the present invention are as follows: composition of reaction gas, ethylene (C)2H4) 28.0 +/-1.0 mol%; oxygen (O)2) 7.4 +/-0.2 mol%; carbon dioxide (CO)2) < 5.0 mol%; cause steady qi (N)2) And the rest; 0.1-2.0ppm of inhibitor dichloroethane; the space velocity is 8000/h; the reactor outlet EO concentration, 3.0 mol%; space-time yield, 470kg EO/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:
selectivity is
Where Δ EO is the difference in ethylene oxide concentration between the reactor outlet gas and the inlet gas, Δ CO2The carbon dioxide concentration difference between the outlet gas and the inlet gas of the reactor is determined, and the average of more than 10 groups of test data is taken as the test result of the day.
The silver content was determined by chemical titration analysis.
The content of the surfactant is determined according to the content of characteristic groups such as carboxyl, hydroxyl, amino, carbonyl, acylamino and the like in the infrared and ultraviolet analysis catalyst.
The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to these examples.
Preparation example
This preparation example serves to illustrate the preparation of support A.
550g of 50-500 mesh trihydrate A12O3And 350g of pseudo-monohydrate A1 sieved with a 200 mesh sieve2O3Putting the mixture into a mixer, uniformly mixing the mixture, transferring the mixture into a kneader, adding 200 ml of 20 wt% nitric acid aqueous solution, kneading the mixture into paste capable of being extruded and molded, extruding and molding the paste into a single-hole Raschig ring column with the outer diameter of 8.0mm, the length of 6.0mm and the inner diameter of 2.0mm, drying the single-hole Raschig ring column at the temperature of 80-120 ℃ for 2 hours to reduce the free water content to below 10 wt% to obtain a green body, then putting the green body into an electric furnace, increasing the temperature from room temperature to 1200-1500 ℃ after 30 hours, and keeping the temperature at the high temperature for 1-6 hours to obtain white α -A12O3Vector A, wherein α -A12O3The content is more than or equal to 90 percent, the crushing strength is 140N, and the specific surface area is 1.3m2Water absorption of 53% and pore volume of 0.5 ml/g.
Comparative example 1
To a stirred glass flask were added 15g of ethylenediamine, 5.5g of ethanolamine, and 19g of deionized water to obtain a mixed solution. And slowly adding the silver oxalate into the obtained mixed solution under stirring, keeping the temperature at 15-35 ℃, completely dissolving the silver oxalate, and adding the silver oxalate in an amount which ensures that the finally prepared impregnation solution contains 24 wt% of silver. Adding 0.15g of cesium nitrate and 0.2g of ammonium perrhenate, and adding deionized water to make the total mass of the solution reach 100g to prepare impregnation liquid for later use. The carrier A30g was taken and placed in a vacuum-evacuable container. Vacuumizing to a vacuum degree lower than 10mmHg, adding the above impregnation liquid, immersing the carrier, and keeping for 30 minutes. After which the excess impregnation solution is leached away. The impregnated carrier is heated in air flow at 250 ℃ for 5 minutes and cooled to prepare the silver catalyst DS 1.
Example 1
Support A was soaked with 50g of 5 wt% aqueous dodecyldimethylsulfopropyl betaine (from the avadin reagent) for half an hour at 30g, after which excess liquid was leached off and then dried at 120 ℃ for 1 hour before use. In a glass flask with stirring, 15g of ethylenediamine, 5.5g of ethanolamine, and 19g of deionized water were added to obtain a mixed solution. And slowly adding the silver oxalate into the obtained mixed solution under stirring, keeping the temperature at 15-35 ℃, completely dissolving the silver oxalate, and adding the silver oxalate in an amount which ensures that the finally prepared impregnation solution contains 24 wt% of silver. Adding 0.15g of cesium nitrate and 0.2g of ammonium perrhenate, and adding deionized water to make the total mass of the solution reach 100g to prepare impregnation liquid for later use. The carrier A which is soaked in dodecyl dimethyl sulfopropyl betaine aqueous solution and dried is put into a container which can be vacuumized. Vacuumizing to a vacuum degree lower than 10mmHg, adding the above impregnation liquid, immersing the carrier, and keeping for 30 minutes. After which the excess impregnation solution is leached away. Drying the impregnated carrier at 100 ℃ for 8 hours, heating the dried impregnated carrier in air flow at 250 ℃ for 5 minutes, and cooling the dried impregnated carrier to obtain the silver catalyst S1, wherein the content of the dodecyl dimethyl sulfopropyl betaine component is 100ppm based on the weight of the silver catalyst S1.
Example 2
To a stirred glass flask were added 15g of ethylenediamine, 5.5g of ethanolamine, an aqueous solution of tetradecanamidopropyl hydroxypropyl sulfobetaine (from avastin reagent), and an appropriate amount of deionized water to obtain a mixed solution. Slowly adding silver oxalate into the obtained mixed solution under stirring, keeping the temperature at 15-35 deg.C, dissolving silver oxalate completely, and adding silver oxalate in an amount such that the finally obtained impregnation solution contains 24 wt% of silver and 5 wt% of tetradecylamidopropyl hydroxypropyl sulfobetaine. Adding 0.15g of cesium nitrate and 0.2g of ammonium perrhenate, and adding deionized water to make the total mass of the solution reach 100g to prepare impregnation liquid for later use. The carrier A30g was taken and placed in a vacuum-evacuable container. Vacuumizing to a vacuum degree lower than 10mmHg, adding the above impregnation liquid, immersing the carrier, and keeping for 30 minutes. After which the excess impregnation solution is leached away. The impregnated carrier was dried at 100 ℃ for 8 hours, heated at 250 ℃ for 5 minutes in an air stream, and cooled to obtain silver catalyst S2 in which the content of tetradecanamidopropyl hydroxypropyl sulfobetaine component was 100ppm based on the weight of silver catalyst S2.
Example 3
To a stirred glass flask were added 15g of ethylenediamine, 5.5g of ethanolamine, and 19g of deionized water to obtain a mixed solution. And slowly adding the silver oxalate into the obtained mixed solution under stirring, keeping the temperature at 15-35 ℃, completely dissolving the silver oxalate, and adding the silver oxalate in an amount which ensures that the finally prepared impregnation solution contains 24 wt% of silver. Adding 0.15g of cesium nitrate and 0.2g of ammonium perrhenate, and adding deionized water to make the total mass of the solution reach 100g, so as to prepare impregnation liquid for later use. The carrier A30g was taken and placed in a vacuum-evacuable container. Vacuumizing to a vacuum degree lower than 10mmHg, adding the above impregnation liquid, immersing the carrier, and keeping for 30 minutes. After which the excess impregnation solution is leached away. The impregnated carrier was dried at 100 ℃ for 8 hours, heated at 250 ℃ for 5 minutes in an air stream, cooled, and then soaked with a 0.05 wt% aqueous solution of octadecyl dihydroxyethyl amine oxide (available from alatin reagent) for 10 minutes, and then dried at 120 ℃ for 24 hours, to obtain silver catalyst S3, in which the content of the octadecyl dihydroxyethyl amine oxide component was 100ppm, based on the weight of silver catalyst S3.
Example 4
To a stirred glass flask were added 15g of ethylenediamine, 5.5g of ethanolamine, and 19g of deionized water to obtain a mixed solution. And slowly adding the silver oxalate into the obtained mixed solution under stirring, keeping the temperature at 15-35 ℃, completely dissolving the silver oxalate, and adding the silver oxalate in an amount which ensures that the finally prepared impregnation solution contains 24 wt% of silver. Adding 0.15g of cesium nitrate and 0.2g of ammonium perrhenate, and adding deionized water to make the total mass of the solution reach 100g, so as to prepare impregnation liquid for later use. The carrier A30g was taken and placed in a vacuum-evacuable container. Vacuumizing to a vacuum degree lower than 10mmHg, adding the above impregnation liquid, immersing the carrier, and keeping for 30 minutes. Thereafter leaching to remove excess impregnation liquor and drying at 100 ℃ for 8 hours; then soaking the solid phase semi-finished product again for 20 minutes by using a 5 weight percent aqueous solution of tetradecanamidopropyl hydroxypropyl sulfobetaine (purchased from an avastin reagent), draining and drying at 100 ℃ for 8 hours; finally, the mixture was heated in an air stream at 250 ℃ for 5 minutes to obtain silver catalyst S4 in which the content of tetradecanamidopropyl hydroxypropyl sulfobetaine component was 100ppm based on the weight of silver catalyst S4.
Example 5
A silver catalyst was prepared by the same procedure as in example 1, except that the carrier A was soaked with 50g of 0.5% by weight aqueous solution of dodecyldimethylsulfopropyl betaine (available from the avadin reagent) for 30 and 30g hours, and then leached to remove excess liquid, and then dried at 120 ℃ for 1 hour to prepare a carrier. Finally, the silver catalyst S5 was prepared, in which the content of the dodecyldimethylsulfopropyl betaine component was 50ppm based on the weight of the silver catalyst S5.
Example 6
A silver catalyst was prepared by following the same procedure as in example 1, except that the carrier A was soaked with 50g of a 7% by weight aqueous solution of dodecyldimethylsulfopropylbetaine (available from the avadin reagent) for 30g half an hour, and then leached to remove an excess liquid, and then dried at 120 ℃ for 1 hour to be used as a carrier. Finally, the silver catalyst S6 was prepared, in which the content of the dodecyldimethylsulfopropyl betaine component was 300ppm based on the weight of the silver catalyst S6.
Example 7
A silver catalyst was prepared by following the same procedure as in example 1, except that the carrier A was soaked with 50g of a 12% by weight aqueous solution of dodecyldimethylsulfopropylbetaine (available from the avadin reagent) for 30g half an hour, and then leached to remove an excess liquid, and then dried at 120 ℃ for 1 hour to be used as a carrier. Finally, the silver catalyst S7 was prepared, in which the content of the dodecyldimethylsulfopropyl betaine component was 500ppm based on the weight of the silver catalyst S7.
Example 8
A silver catalyst was prepared by the same procedure as in example 1, except that the carrier A was soaked with 50g of a 5% by weight aqueous solution of octadecylamidopropylamine oxide (available from the reagent for alatin) for 30g for half an hour, after which excess liquid was leached out and then dried at 120 ℃ for 1 hour to be ready for use as a carrier. Finally, the silver catalyst S8 was prepared.
Example 9
A silver catalyst was prepared by the same procedure as in example 1, except that the carrier A30g was soaked with 50g of a 5% by weight aqueous solution of zwitterionic polyacrylamide (average molecular weight 800 ten thousand, available from the avadin reagent) for half an hour, after which excess liquid was leached out and then dried at 120 ℃ for 1 hour before being ready for use as a carrier. Finally, the silver catalyst S9 was prepared.
Example 10
A silver catalyst was prepared by following the same procedure as in example 1, except that the carrier A was soaked in 50g of a mixed aqueous solution containing 2.5% by weight of glycine and 2.5% by weight of lauric oil for 30g for half an hour, and then leached to remove an excessive liquid, and then dried at 120 ℃ for 1 hour to be used as a carrier. Finally, the silver catalyst S10 was prepared.
Example 11
A silver catalyst was prepared by following the same procedure as in example 1, except that 50g of a mixed aqueous solution of 4% by weight of tetradecanamidopropylhydroxypropylsulfobetaine (available from the avadin reagent) and 1% by weight of zwitterionic polyacrylamide (average molecular weight 800 ten thousand, available from the avadin reagent) was used to soak the carrier A30g for half an hour, after which the excess liquid was leached out and then dried at 120 ℃ for 1 hour to prepare a carrier. Finally, the silver catalyst S11 was prepared.
Example 12
The silver catalyst was prepared by the same procedure as in example 1, except that the same amount of tetradecanamidopropylhydroxypropyl sulfobetaine was used instead of dodecyldimethylsulfopropyl betaine. Finally, the silver catalyst S12 was prepared.
Example 13
The silver catalyst was prepared by the same procedure as in example 3, except that the same amount of tetradecanamidopropylhydroxypropylsultaine was used instead of the octadecyl dihydroxyethyl amine oxide. Finally, the silver catalyst S13 was prepared.
Test example
Performance evaluation: the activity and selectivity of each catalyst sample was measured using a microreactor evaluation unit under the process conditions described in the "catalyst Performance determination" section above, and the results are shown in Table 1. The reaction temperatures in Table 1 are such that the cumulative EO production amounts to 500T/M3Value at catalyst time, selectivity, cumulative EO productionUp to 500T/M3Average value in catalyst.
TABLE 1
As can be seen from Table 1, the catalyst of the present invention has lower reaction temperature and better average selectivity accumulated for a long time, thus showing that the silver catalyst containing the surfactant of the present invention has obviously simultaneously improved activity, stability and selectivity and better catalytic activity compared with the common silver catalyst, and is particularly suitable for the reaction of producing ethylene oxide by oxidizing ethylene.
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.
Claims (14)
1. A silver catalyst for the oxidation of ethylene to produce ethylene oxide, the silver catalyst comprising:
i. a porous alumina support; and the number of the first and second groups,
silver, a surfactant component and optionally at least one of the following components supported on said porous alumina support: an alkali metal assistant, an alkaline earth metal assistant, a rhenium assistant and a rhenium assistant; the surfactant component is a water-soluble amphoteric surfactant.
2. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 1, wherein the surfactant component is contained in an amount of 5 to 10000ppm, preferably 10 to 5000ppm, further preferably 15 to 1000ppm, and more preferably 20 to 400ppm, based on the total weight of the silver catalyst.
3. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 1, wherein the amphoteric surfactant is preferably at least one selected from betaine-type surfactants, amine oxide-type surfactants, zwitterionic polyacrylamides, amino acid-type surfactants, and amphoteric imidazoline-type surfactants; further preferably, the amphoteric surfactant is selected from at least one of dodecyl dimethyl sulfopropyl betaine, dodecyl ethoxy sulfobetaine, tetradecylamidopropyl hydroxypropyl sulfobetaine, phospholipide betaine, octadecyl dihydroxyethyl amine oxide, octadecyl amidopropyl amine oxide, zwitterionic polyacrylamide, lauryl oil and glycine.
4. The silver catalyst for ethylene oxidation to ethylene oxide according to any one of claims 1 to 3, wherein the silver catalyst is a silver oxide catalyst,
the content of the silver is 1 to 35wt percent, preferably 5 to 30wt percent calculated by silver element;
the content of the alkali metal additive is 5-2000ppm, preferably 10-1500ppm calculated by alkali metal elements;
the content of the alkaline earth metal auxiliary agent is 5-8000ppm, preferably 10-3000ppm calculated by alkaline earth metal elements;
the content of the rhenium auxiliary agent is 5-1500ppm, preferably 10-1000ppm calculated by rhenium element;
the content of the rhenium synergist is 5-1000ppm, preferably 10-500ppm calculated by rhenium synergist element.
5. The silver catalyst for ethylene oxidation to ethylene oxide according to any one of claims 1 to 3, wherein the porous alumina support has the following characteristics of α -A12O3The content is more than or equal to 85 percent, preferably α -A12O3The content is more than or equal to 90 percent; the crushing strength of the particles is more than or equal to 20N, preferably 30-150N; the specific surface area is 0.2-7.0m2A/g, preferably from 0.5 to 6.0m2Water absorption of 30% or more, preferably 40% or more, and pore volume of 0.35-0.85ml/g, preferably 0.40-0.8 ml/g.
6. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 1, wherein the silver catalyst is prepared by a method comprising the steps of:
a. impregnating the porous alumina carrier with a silver-containing impregnating solution to obtain a solid-liquid mixture;
b. b, performing solid-liquid separation on the solid-liquid mixture obtained in the step a, and drying the obtained solid phase;
c. activating the dried solid phase obtained in the step b;
wherein, in any step a to c, a surfactant or a precursor thereof is added for treatment;
the silver-containing impregnating solution contains a silver compound, an organic amine, water and optionally at least one of the following components: alkali metal assistant, alkaline earth metal assistant, rhenium assistant and rhenium assistant.
7. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 6, wherein the surfactant or precursor treatment employs a solution containing a surfactant or precursor thereof; the solution containing the surfactant or the precursor thereof comprises the surfactant or the precursor thereof and a solvent; the solvent is preferably at least one selected from the group consisting of water, ethanol, and acetone;
the concentration of the surfactant or the precursor thereof in the solution containing the surfactant or the precursor thereof is preferably 0.001 wt% to 10 wt%, and more preferably 0.002 wt% to 8 wt%.
8. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 6, wherein the surfactant or a precursor thereof is added to the silver-containing impregnation solution; the concentration of the surfactant or the precursor thereof in the silver-containing impregnation liquid is preferably 0.001 wt% to 10 wt%, and more preferably 0.002 wt% to 8 wt%.
9. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 6 or 7, wherein in step a, the carrier is treated with a surfactant or a precursor thereof before, during or after impregnation, and optionally dried after the treatment with the surfactant or the precursor thereof.
10. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 6 or 7, wherein the step b comprises a step of treating the silver catalyst with a surfactant or a precursor thereof before or after drying, and optionally drying the silver catalyst after treating the silver catalyst with a surfactant or a precursor thereof.
11. The silver catalyst for ethylene oxide production by oxidation of ethylene according to claim 6 or 7, wherein in step c, the step of treating with a surfactant or a precursor thereof is performed before or after the activation, and the step of drying is performed after the treatment with a surfactant or a precursor thereof.
12. The silver catalyst for ethylene oxidation to ethylene oxide according to claim 6 or 7, wherein the surfactant or precursor treatment thereof comprises soaking and/or spraying.
13. The method for preparing a silver catalyst according to any one of claims 1 to 12, comprising the steps of:
a. impregnating the porous alumina carrier with a silver-containing impregnating solution to obtain a solid-liquid mixture;
b. b, performing solid-liquid separation on the solid-liquid mixture obtained in the step a, and drying the obtained solid phase;
c. activating the dried solid phase obtained in the step b;
wherein, in any step a to c, a surfactant or a precursor thereof is added for treatment;
the silver-containing impregnating solution contains a silver compound, an organic amine, water and optionally at least one of the following components: alkali metal assistant, alkaline earth metal assistant, rhenium assistant and rhenium assistant.
14. Use of a silver catalyst according to any one of claims 1 to 12 in the epoxidation of ethylene to ethylene oxide.
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| CN115487809A (en) * | 2021-06-17 | 2022-12-20 | 中国石油化工股份有限公司 | Preparation method of silver catalyst for producing ethylene oxide by ethylene oxidation, silver catalyst and application |
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