CN112007625B - Alpha-alumina carrier, preparation method, silver catalyst and application - Google Patents
Alpha-alumina carrier, preparation method, silver catalyst and application Download PDFInfo
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- CN112007625B CN112007625B CN201910452543.XA CN201910452543A CN112007625B CN 112007625 B CN112007625 B CN 112007625B CN 201910452543 A CN201910452543 A CN 201910452543A CN 112007625 B CN112007625 B CN 112007625B
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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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
- B01J21/04—Alumina
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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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts 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
- B01J23/66—Silver or gold
- B01J23/68—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/688—Silver 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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- 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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- 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 an alpha-alumina carrier, a preparation method, a silver catalyst and application. The alpha-alumina carrier is prepared by mixing, kneading, forming and roasting a solid mixture and a binder aqueous solution; the solid mixture is doped with waste silver catalyst carrier powder, and the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier; the median granularity of the waste silver catalyst carrier powder is 40-5000 meshes; the mass of the waste silver catalyst carrier powder accounts for 0.1-50.0% of the total mass of the solid mixture. The silver catalyst prepared by the carrier shows activity and selectivity equivalent to those of the silver catalyst prepared by the conventional method in the reaction of producing ethylene oxide by ethylene epoxidation. The invention realizes the effective utilization of waste resources, saves energy and increases efficiency.
Description
Technical Field
The invention belongs to the field of catalysts, and particularly relates to an alpha-alumina carrier, a preparation method, a silver catalyst and application thereof, in particular to an alpha-alumina carrier prepared by utilizing a recovered silver catalyst carrier, a method for preparing an alpha-alumina carrier by utilizing a recovered silver catalyst carrier, an alpha-alumina carrier prepared by the method, a silver catalyst comprising the alpha-alumina carrier, and application of the alpha-alumina carrier and the silver catalyst in olefin epoxidation reaction.
Background
To date, silver catalysts remain the only effective catalysts for the commercial epoxidation of ethylene to ethylene oxide. In the prior art, silver catalysts typically have, in addition to a silver component, one or more other elements co-deposited therewith to improve the catalytic performance of the silver catalyst, and the support is typically composed of a-alumina which is resistant to high temperatures and has a suitable specific surface and pore structure.
Materials for preparing the alpha-alumina support of the silver catalyst generally include: alpha-alumina powder and/or aluminium hydroxide, binder, thermally decomposable pore-forming agent, lubricant and auxiliary agent. The SD company patent discloses the preparation of an alpha-alumina support with at least one of the alpha-alumina hydration precursors and optionally alpha-alumina and a binder. PCT/US2003/005902 by Shell company discloses 50-95 wt% of a first particulate alpha-alumina, wherein the median pore size (d 50) is 5-100 μm and 5-50 wt% of a second particulate alpha-alumina, wherein the median pore size is less than the d50 of the first particulate alpha-alumina and is 1-10 μm. The alpha-alumina carrier prepared by Noritake corporation of Japan has a double-distributed pore size structure, and they also studied that alpha-alumina of different particle sizes is used as a raw material, and the alpha-alumina carrier is prepared by kneading and roasting at about 500 ℃.
After industrial application, the waste silver catalyst is subjected to recovery treatment of silver and an auxiliary component thereof to obtain a waste alpha-alumina carrier. In 2017, the total silver catalyst filling amount in China is about 6000m 3 By 2019, the total silver catalyst loading was expected to be about 11000m 3 . This results in a large amount of spent silver catalyst support to be treated or utilized. However, no waste silver can be used at presentSuitable methods for recycling the catalyst support.
Disclosure of Invention
In view of the above-mentioned prior art, through extensive and intensive studies in the field of α -alumina carrier and silver catalyst preparation, the inventors of the present invention pulverized the recovered α -alumina carrier of the waste silver catalyst into α -alumina powder of a certain particle size, and selected this powder to prepare a silver catalyst carrier, a silver catalyst which exhibits catalytic performance comparable to that of the existing catalysts in the reaction of preparing an epoxy compound by olefin epoxidation. The invention realizes the recycling of the waste carrier and fully utilizes the resources.
The first aspect of the present invention provides an α -alumina carrier prepared by mixing, kneading, shaping, and calcining a solid mixture and an aqueous binder solution; the solid mixture is doped with waste silver catalyst carrier powder, and the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier; the median granularity of the waste silver catalyst carrier powder is 40-5000 meshes; the mass of the waste silver catalyst carrier powder accounts for 0.1-50.0% of the total mass of the solid mixture.
The second aspect of the present invention provides a method for preparing an α -alumina carrier, comprising the steps of:
step I, crushing a waste silver catalyst carrier into alpha-alumina powder, wherein the median particle size of the alpha-alumina powder is 40-5000 meshes; the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier;
step II, obtaining a solid mixture comprising the following components: a. alpha-alumina powder obtained in the step I; b. alumina trihydrate; c. pseudo-boehmite; d. a fluorine-containing compound; e. an alkaline earth metal compound; wherein the mass of the alpha-alumina powder accounts for 0.1-50.0% of the total mass of the solid mixture;
step III, mixing the solid mixture obtained in the step II with an aqueous binder solution to obtain an alpha-alumina carrier precursor mixture;
and IV, kneading, forming and roasting the alpha-alumina carrier precursor mixture obtained in the step III to obtain the alpha-alumina carrier.
A third aspect of the present invention provides an α -alumina support prepared by the above preparation method.
In a fourth aspect the present invention provides a silver catalyst comprising the above-described alpha-alumina support and deposited thereon a catalytically effective amount of silver, optionally an alkali metal promoter and/or alkaline earth metal promoter, and optionally a rhenium promoter and co-promoters thereof.
In a fifth aspect the present invention provides the use of an alpha-alumina support and/or a silver catalyst as described above in the epoxidation of an olefin.
The invention adds the waste silver catalyst alpha-alumina carrier powder in the preparation process of the alpha-alumina carrier, and controls the performance of the prepared alpha-alumina carrier by adjusting the granularity and the addition amount of the waste alpha-alumina carrier powder, and the specific surface area of the prepared carrier is 1.0-50.0 m 2 Preferably 1.1 to 10.0m 2 /g; the water absorption rate of the carrier is more than or equal to 30%, preferably 40% -70%; the crushing strength of the carrier is 30-300N/granule. The silver catalyst prepared by the carrier shows activity and selectivity equivalent to those of the silver catalyst prepared by the conventional method in the reaction of producing ethylene oxide by ethylene epoxidation. Therefore, the preparation method of the silver catalyst carrier realizes the effective utilization of waste resources, and saves energy and increases efficiency.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The first aspect of the present invention provides an α -alumina carrier prepared by mixing, kneading, shaping, and calcining a solid mixture and an aqueous binder solution; the solid mixture is doped with waste silver catalyst carrier powder, and the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier; the median granularity of the waste silver catalyst carrier powder is 40-5000 meshes; the mass of the waste silver catalyst carrier powder accounts for 0.1-50.0% of the total mass of the solid mixture, preferably 0.1-40.0%, and more preferably 1.0-30.0%; according to a preferred embodiment of the invention, the mass of the waste silver catalyst carrier powder accounts for 12.0-25.0% of the total mass of the solid mixture.
The waste silver catalyst used in the invention refers to a waste silver catalyst which can be used for olefin epoxidation reaction and takes alpha-alumina as a carrier, and correspondingly, the waste silver catalyst carrier refers to the carrier part of the waste silver catalyst which remains after silver and auxiliary components are recovered. However, the present invention is not limited to the waste silver catalyst which is obtained by subjecting an olefin to an epoxidation reaction, and any catalyst having the above characteristics may be used as long as it is a waste catalyst obtained by subjecting a catalyst having the above characteristics to a catalytic reaction.
Although the present invention is not limited to the specific sources of the "spent silver catalyst" and "spent silver catalyst support", it preferably refers to the spent silver catalyst (usually referred to as "three wastes") obtained after the epoxidation of olefins in the industry and the support portion of the silver catalyst remaining after recovery of silver and promoter components. The present invention is not particularly limited to a specific recovery process, as long as it is a silver catalyst carrier remaining after recovery of silver and an auxiliary component.
In the invention, the terms "waste silver catalyst" and "recovered silver catalyst" refer to the same meaning; the meanings indicated by the "spent silver catalyst carrier", "recovered silver catalyst carrier", "spent alpha-alumina carrier" are also the same.
According to the invention, the solid mixture also comprises other components required for preparing a silver catalyst carrier for olefin epoxidation, and specifically comprises: alumina trihydrate, pseudo-boehmite, fluorine-containing compounds and alkaline earth metal compounds; wherein, the liquid crystal display device comprises a liquid crystal display device,
the alumina trihydrate is preferably selected from gibbsite and/or bayerite; the mass of the alumina trihydrate is preferably 5.0 to 85.0% of the total mass of the solid mixture, and more preferably 20.0 to 80.0%.
The weight of the pseudo-boehmite is preferably 2.0 to 75.0% of the total weight of the solid mixture, and more preferably 10.0 to 60.0%.
In the invention, alumina trihydrate and pseudo-boehmite are converted into transition phase alumina through roasting and dehydration, and finally converted into alpha-alumina. The fluorine-containing compound can promote transition phase alumina to alpha-alumina in the roasting process, eliminate unnecessary micropores and reduce micropores below 0.1 mu m. The fluorine-containing compound is preferably selected from one or more of hydrogen fluoride, aluminum fluoride, ammonium fluoride, magnesium fluoride, lithium fluoride and cryolite; the mass of the fluorine-containing compound is preferably 0.01 to 20.0% by mass, more preferably 0.1 to 10.0% by mass of the total mass of the solid mixture.
In the present invention, the alkaline earth metal compound is added for the purpose of improving the performance of the α -alumina support. The alkaline earth metal compound is preferably selected from one or more of oxides, sulfates, nitrates and oxalates of calcium, strontium and barium; the mass of the alkaline earth metal compound is preferably 0.01 to 6.00% by mass, more preferably 0.01 to 3.00% by mass of the total mass of the solid mixture.
In the invention, the aqueous binder solution is used for forming an aluminum sol with pseudo-boehmite in the solid mixture, so that the components are bonded together to form an extrudable paste. The aqueous binder solution may be at least one selected from the group consisting of aqueous citric acid solution, aqueous nitric acid solution, aqueous formic acid solution, aqueous acetic acid solution, aqueous propionic acid solution, and aqueous hydrochloric acid solution. The amount of the aqueous binder solution and the content of the binder therein are limited to meet the requirements of binding and forming into an extrudable paste. Typically, the weight ratio of the aqueous binder solution to the solid mixture may be 1:2 to 10; the mass ratio of the binder to the water in the aqueous binder solution is preferably 1:0.2 to 10.
In the present invention, the term "water" preferably refers to deionized water unless otherwise specified.
The mixing of the components of the solid mixture according to the invention with the aqueous binder solution can be carried out in any manner, not necessarily in a particular order.
In the preparation of the silver catalyst support of the present invention, the conditions of kneading, molding and calcination may be all conventional conditions in the art. For example, the kneading is carried out in a kneader for a kneading time of 5 to 90 minutes; the shaping is carried out in a shaping machine, and the shape after shaping comprises a sphere shape, a Raschig ring shape, a porous cylinder shape, a block shape, a pill shape, a clover shape or a clover shape; the drying is carried out at 80-120 ℃; the calcination may include a temperature programmed and constant calcination process at 1100-1600 c for 0.5-30 hours to convert substantially all (e.g., over 90%) of the alumina to alpha-alumina.
The second aspect of the present invention provides a method for preparing an α -alumina carrier, comprising the steps of:
step I, crushing a waste silver catalyst carrier into alpha-alumina powder, wherein the median particle size of the alpha-alumina powder is 40-5000 meshes; the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier;
step II, obtaining a solid mixture comprising the following components: a. alpha-alumina powder obtained in the step I; b. alumina trihydrate; c. pseudo-boehmite; d. a fluorine-containing compound; e. an alkaline earth metal compound; wherein the mass of the alpha-alumina powder accounts for 0.1-50.0% of the total mass of the solid mixture, preferably 0.1-40.0%, and more preferably 1.0-30.0%; according to a preferred embodiment of the present invention, the mass of the α -alumina powder is 12.0% to 25.0% of the total mass of the solid mixture;
step III, mixing the solid mixture obtained in the step II with an aqueous binder solution to obtain an alpha-alumina carrier precursor mixture;
and IV, kneading, forming and roasting the alpha-alumina carrier precursor mixture obtained in the step III to obtain the alpha-alumina carrier.
In the preparation method of the present invention, the specific components and amounts of the alumina trihydrate, the pseudo-boehmite, the fluorine-containing compound, the alkaline earth metal compound, and the aqueous binder solution are the same as those described above, and are not described in detail herein.
In the preparation step of the silver catalyst support of the present invention, the conditions of kneading, molding and calcination may be all conventional conditions in the art. The specific conditions are the same as those described above, and will not be described again here.
According to some embodiments of the present invention, to facilitate extrusion of the shaped article, a shaping aid may be added to the solid mixture, the shaping aid comprising at least one of petrolatum, graphite, paraffin wax and vegetable oil.
A third aspect of the present invention provides an α -alumina support prepared by the above preparation method. The alpha-alumina support preferably has the following characteristics: the specific surface area is 1.0-50.0 m 2 Preferably 1.1 to 10.0m 2 /g; the water absorption rate is more than or equal to 30 percent, preferably 40 to 70 percent; the crushing strength is 30-300N/grain.
In a fourth aspect the present invention provides a silver catalyst comprising the above-described alpha-alumina support and deposited thereon a catalytically effective amount of silver, optionally an alkali metal promoter and/or alkaline earth metal promoter, and optionally a rhenium promoter and co-promoters thereof.
The silver catalyst can be prepared by a preparation method comprising the following steps: immersing the alpha-alumina carrier in a solution containing organic amine, a silver compound and an auxiliary agent, and carrying out activation heat treatment to obtain a silver catalyst; the promoter comprises an optional alkali metal promoter and/or alkaline earth metal promoter, and an optional rhenium promoter and co-promoters thereof.
In the preparation method of the silver catalyst of the present invention, the organic amine may include at least one of pyridine, ethylamine, n-propylamine, n-butylamine, isobutylamine, t-butylamine, sec-butylamine, 1, 2-propylenediamine, 1, 3-propylenediamine, ethylenediamine, 1, 2-butylenediamine, 1, 3-butylenediamine, ethanolamine, propanolamine and butanolamine.
In the silver catalyst of the present invention, the mass content of the alkali metal auxiliary may be 5 to 2000ppm, the alkali metal auxiliary may be selected from at least one of nitrate, sulfate and hydroxide of alkali metal, and the alkali metal may be selected from at least one of lithium, sodium, potassium, rubidium and cesium.
In the silver catalyst of the present invention, the mass content of the alkaline earth metal auxiliary may be 5 to 20000ppm, the alkaline earth metal auxiliary may be selected from at least one of acetate, oxalate, sulfate and nitrate of an alkaline earth metal, and the alkaline earth metal may be selected from at least one of magnesium, calcium, strontium and barium.
In some embodiments of the present invention, the silver catalyst may further include other elements deposited on the alpha-alumina support, the other elements including at least one of phosphorus, boron, chromium, and titanium.
In order to obtain a silver catalyst having a higher silver content and/or additive content, in the preparation method of the silver catalyst of the present invention, the silver catalyst may be prepared by one or more impregnation methods. The promoter of the silver catalyst may be deposited on the support either before, simultaneously with, or after impregnation of the silver, or after activation of the silver compound.
The specific impregnation conditions and the conditions for the activation heat treatment are not particularly limited in the present invention, and may be any conventional conditions in the art.
In a fifth aspect the present invention provides the use of an alpha-alumina support and/or a silver catalyst as described above in the epoxidation of an olefin. For example, a method for producing an epoxy compound by epoxidation of an olefin, wherein the epoxidation of an olefin is carried out in the presence of the above-mentioned silver catalyst. The olefins include, but are not limited to, at least one of styrene, propylene, ethylene, and 1, 3-butadiene.
The present invention will be further described with reference to examples, but the scope of the present invention is not limited to these examples.
The median particle size of the alpha-alumina powder in the present invention is determined using a laser particle sizer.
The method for detecting the physical properties of the alpha-alumina carrier comprises the following steps:
specific surface area of the support: the nitrogen physisorption BET method was used according to International test Standard ISO-9277 using a NOVA2000e type nitrogen physisorption instrument from America Kang Da.
Lateral pressure strength of carrier: and adopting a DL II type intelligent particle strength tester produced by Dalian chemical engineering research institute, randomly selecting 30 carrier samples, measuring radial crushing strength, and taking an average value to obtain the product.
The term "water absorption" as used herein refers to the volume of saturated adsorbed water per unit mass of carrier, in mL/g. The measurement method is as follows: firstly, a certain amount of carrier (assuming the mass of the carrier is m 1 ) After boiling in boiling water for 1h, taking out the carrier, standing on wet gauze with moderate water content to remove excessive water on the surface of the carrier, and finally weighing the mass (assumed to be m) of the carrier after water absorption 2 ) The water absorption of the carrier was calculated according to the following formula. Water absorption= (m) 2 -m 1 )/m 1 /ρ Water and its preparation method Wherein: ρ Water and its preparation method The density of water at temperature and atmospheric pressure was measured.
The various silver catalysts of the present invention were tested for selectivity using a laboratory microreactor ("microreactor") evaluation device. The reactor used in the microreactor 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 catalyst was packed in a volume of 1ml with inert packing in the lower part to allow the catalyst bed to be located in the constant temperature zone of the heating mantle.
The activity and initial selectivity measurement conditions used in the present invention are shown in Table 1:
TABLE 1
After the above reaction conditions were stably reached, the reactor inlet and outlet gas compositions were continuously measured. After the volume shrinkage correction is carried out on the measurement result, the selectivity is calculated according to the following formula:
selectivity of
Where ΔEO is the difference in ethylene oxide concentration in the reactor outlet and inlet gases, ΔCO 2 Is the concentration difference of carbon dioxide in the outlet gas and the inlet gas of the reactor, and takes the average of more than 10 groups of test data as the current timeDay test results.
Comparative example 1
Alpha-alumina carrier preparation: 300.0g gibbsite, 150.0g pseudo boehmite, 8.5g aluminum fluoride and 2.5g barium nitrate are put into a mixer to be uniformly mixed, and then the mixture is transferred into a kneader, and 100 ml of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added, so that the mixture is kneaded into paste capable of being extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1200 ℃, the constant-temperature roasting is carried out for 2 hours, and finally, the temperature is cooled to room temperature, so that the alpha-alumina carrier is obtained and named as C-1. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: respectively dissolving 700g of silver nitrate and 325g of ammonium oxalate in 750ml of deionized water and 250ml of deionized water to respectively obtain a silver nitrate solution and an ammonium oxalate solution, mixing the two solutions under intense stirring to generate white silver oxalate precipitate, aging for 30min, filtering, and washing the precipitate with deionized water until no nitrate ions exist. The silver content of the filter cake is about 60% by mass and the water content is about 15% by mass, and the filter cake is a paste. Into a glass flask with stirring, 300.0g of ethylenediamine, 110.0g of ethanolamine and 375.0g of deionized water were added to obtain a mixed solution, and the above-prepared silver oxalate paste was added with continuous stirring, and the temperature was kept below 40 ℃ to dissolve all the silver oxalate. Then adding 2.5g cesium nitrate, 3.0g barium acetate and 0.6g ammonium perrhenate in turn, adding deionized water to make the total mass of the solution reach 2000g, and uniformly mixing to prepare an impregnating solution for later use. 100g of carrier is taken, placed in a glass container capable of being vacuumized, poured with prepared impregnating solution, fully immersed in the carrier, vacuumized to be lower than 10mmHg, kept for about 15min, and then leached to remove redundant solution. And finally, placing the impregnated carrier sample in air at 340 ℃ for heating for 3min, and cooling to obtain the silver catalyst.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
Example 1
Alpha-alumina carrier preparation: the waste silver catalyst carrier is crushed into alpha-alumina powder with the median particle size of 4000 meshes, 10g of alpha-alumina powder, 290.0g of gibbsite, 150.0g of pseudo-boehmite, 8.5g of aluminum fluoride and 2.5g of barium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, and 100 milliliters of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added to be kneaded into paste capable of being extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1200 ℃, the constant-temperature roasting is carried out for 2 hours, and finally, the temperature is cooled to room temperature, so that the alpha-alumina carrier is obtained and named as S-1. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: the silver catalyst was prepared in the same manner as in comparative example 1.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
Example 2
Alpha-alumina carrier preparation: the waste silver catalyst carrier is crushed into alpha-alumina powder with the median particle size of 2000 meshes, 50g of alpha-alumina powder, 250.0g of gibbsite, 150.0g of pseudo-boehmite, 8.5g of aluminum fluoride and 2.5g of barium nitrate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, and 100 milliliters of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added to be kneaded into paste capable of being extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1200 ℃, the constant-temperature roasting is carried out for 2 hours, and finally, the temperature is cooled to room temperature, so that the alpha-alumina carrier is obtained and named as S-2. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: the silver catalyst was prepared in the same manner as in comparative example 1.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
Comparative example 2
Alpha-alumina carrier preparation: 200.0g of Bayer stone, 200.0g of pseudo-boehmite, 8.0g of aluminum fluoride and 1.5g of barium sulfate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, and 100 ml of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added to be kneaded into paste capable of being extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1350 ℃, the constant-temperature roasting is carried out for 10 hours, and finally the column is cooled to room temperature to obtain the alpha-alumina carrier which is named as C-2. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: respectively dissolving 700g of silver nitrate and 325g of ammonium oxalate in 750m and 250ml of deionized water to respectively obtain silver nitrate and ammonium oxalate solutions, mixing the two solutions under intense stirring to generate white silver oxalate precipitate, aging for 30min, filtering, and washing the precipitate with deionized water until no nitrate ions exist. The silver content of the filter cake is about 60% by mass and the water content is about 15% by mass, and the filter cake is a paste. Into a glass flask with stirring, 300.0g of ethylenediamine, 110.0g of ethanolamine and 375.0g of deionized water were added to obtain a mixed solution, and the above-prepared silver oxalate paste was added with continuous stirring, and the temperature was kept below 40 ℃ to dissolve all the silver oxalate. Then adding 3.0g cesium acetate, 3.5g barium acetate and 0.6g ammonium perrhenate in sequence, adding deionized water to make the total mass of the solution reach 2000g, and uniformly mixing to prepare an impregnating solution for later use. 100g of carrier is taken, placed in a glass container capable of being vacuumized, poured with prepared impregnating solution, fully immersed in the carrier, vacuumized to be lower than 10mmHg, kept for about 15min, and then leached to remove redundant solution. And finally, placing the impregnated carrier sample in air at 340 ℃ for heating for 3min, and cooling to obtain the silver catalyst.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
Example 3
Alpha-alumina carrier preparation: the waste silver catalyst carrier is crushed into alpha-alumina powder with the median granularity of 700 meshes, 100g of alpha-alumina powder, 100.0g of bayerite, 200.0g of pseudo-boehmite, 8.0g of aluminum fluoride and 1.5g of barium sulfate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, and 100 milliliters of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added to be kneaded into paste capable of being extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1350 ℃, the constant-temperature roasting is carried out for 10 hours, and finally the column is cooled to room temperature, so that the alpha-alumina carrier is obtained and named as S-3. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: the silver catalyst was prepared in the same manner as in comparative example 1.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
Example 4
Alpha-alumina carrier preparation: the waste silver catalyst carrier is crushed into alpha-alumina powder with the median granularity of 1000 meshes, 60g of alpha-alumina powder, 140.0g of bayerite, 200.0g of pseudo-boehmite, 8.0g of aluminum fluoride and 1.5g of barium sulfate are put into a mixer to be uniformly mixed, the mixture is transferred into a kneader, and 100 milliliters of dilute nitric acid (nitric acid: water=1:3, volume ratio) is added to be kneaded into paste which can be extruded and formed. Finally, the paste is put into a forming machine and extruded into five-hole columns, and the five-hole columns are dried for more than 24 hours at the temperature of 80-120 ℃ to reduce the free water content to below 10 percent. And then placing the dried five-hole column into a bell kiln for roasting, wherein the roasting temperature is 1300 ℃, the constant-temperature roasting is carried out for 10 hours, and finally the temperature is cooled to room temperature, so that the alpha-alumina carrier is obtained and named as S-4. The relevant physical property data of the support are shown in Table 2.
Preparation of silver catalyst: the silver catalyst was prepared in the same manner as in comparative example 1.
Evaluation of silver catalyst: the activity and selectivity of the catalyst were measured under the aforementioned process conditions using a microreactor evaluation device on the catalyst thus prepared, and the test results are shown in Table 3.
TABLE 2
| Specific surface area (m) 2 /g) | Intensity (N/grain) | Water absorption (%) | |
| Comparative example 1 | 1.20 | 151 | 52.1 |
| Example 1 | 1.17 | 130 | 52.7 |
| Example 2 | 1.21 | 125 | 51.8 |
| Comparative example 2 | 1.49 | 217 | 52.4 |
| Example 3 | 1.45 | 184 | 51.7 |
| Example 4 | 1.57 | 157 | 53.1 |
TABLE 3 Table 3
| Initial Selectivity (%) | Initial reaction temperature (. Degree. C.) | |
| Comparative example 1 | 82.4 | 228.5 |
| Example 1 | 82.3 | 227.7 |
| Example 2 | 82.6 | 228.3 |
| Comparative example 2 | 81.9 | 226.7 |
| Example 3 | 82.4 | 226.5 |
| Example 4 | 83.1 | 225.1 |
As can be seen from the data in tables 2 and 3, the recovered alpha-alumina carrier of the waste silver catalyst is crushed into alpha-alumina powder with a certain granularity, the strength of the silver catalyst carrier prepared by using the powder is slightly reduced, but the strength requirement of the silver catalyst carrier for industrial application is still satisfied, and the silver catalyst prepared by using the carrier has the same good catalytic performance in the reaction of preparing epoxy compounds by ethylene epoxidation.
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.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
Claims (30)
1. An alpha-alumina carrier is characterized in that the alpha-alumina carrier is prepared by mixing, kneading, forming and roasting a solid mixture and a binder aqueous solution; the solid mixture is doped with waste silver catalyst carrier powder, and the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier; the median particle size of the waste silver catalyst carrier powder is 40-5000 meshes; the mass of the waste silver catalyst carrier powder accounts for 0.1% -50.0% of the total mass of the solid mixture;
the solid mixture further comprises: alumina trihydrate, pseudo-boehmite, fluorine-containing compounds, and alkaline earth metal compounds.
2. The alpha-alumina carrier according to claim 1, wherein the mass of the waste silver catalyst carrier powder accounts for 0.1% -40.0% of the total mass of the solid mixture.
3. The alpha-alumina carrier according to claim 2, wherein the mass of the waste silver catalyst carrier powder accounts for 1.0% -30.0% of the total mass of the solid mixture.
4. The a-alumina carrier of claim 1, wherein the alumina trihydrate is selected from gibbsite and/or bayerite; the mass of the aluminum oxide trihydrate accounts for 5.0-85.0% of the total mass of the solid mixture.
5. The α -alumina carrier of claim 4, wherein the alumina trihydrate comprises 20.0% -80.0% by mass of the total mass of the solid mixture.
6. The α -alumina carrier of claim 1, wherein the pseudo-boehmite comprises 2.0-75.0% by mass of the total mass of the solid mixture.
7. The α -alumina carrier of claim 6, wherein the pseudo-boehmite comprises 10.0% -60.0% by mass of the total mass of the solid mixture.
8. The a-alumina support of claim 1, wherein the fluorine-containing compound is selected from one or more of hydrogen fluoride, aluminum fluoride, ammonium fluoride, magnesium fluoride, lithium fluoride, and cryolite; the mass of the fluorine-containing compound accounts for 0.01% -20.0% of the total mass of the solid mixture.
9. The α -alumina carrier of claim 8, wherein the fluorine-containing compound comprises 0.1% -10.0% by mass of the total mass of the solid mixture.
10. The α -alumina support of claim 1, wherein the alkaline earth metal compound is selected from one or more of oxides, sulfates, nitrates, and oxalates of calcium, strontium, and barium; the mass of the alkaline earth metal compound accounts for 0.01% -6.00% of the total mass of the solid mixture.
11. The α -alumina carrier of claim 10, wherein the alkaline earth metal compound comprises 0.01% -3.00% by mass of the total mass of the solid mixture.
12. The α -alumina support according to claim 1, wherein the aqueous binder solution is selected from at least one of aqueous citric acid, aqueous nitric acid, aqueous formic acid, aqueous acetic acid, aqueous propionic acid and aqueous hydrochloric acid, and the mass ratio of binder to water in the aqueous binder solution is 1: 0.2-10.
13. A method for preparing an alpha-alumina carrier, comprising the following steps:
step I, crushing a waste silver catalyst carrier into alpha-alumina powder, wherein the median particle size of the alpha-alumina powder is 40-5000 meshes; the silver catalyst is a silver catalyst for olefin epoxidation with alpha-alumina as a carrier;
step II, obtaining a solid mixture comprising the following components: a. alpha-alumina powder obtained in the step I; b. alumina trihydrate; c. pseudo-boehmite; d. a fluorine-containing compound; e. an alkaline earth metal compound; wherein the mass of the alpha-alumina powder accounts for 0.1% -50.0% of the total mass of the solid mixture;
step III, mixing the solid mixture obtained in the step II with an aqueous binder solution to obtain an alpha-alumina carrier precursor mixture;
and IV, kneading, forming and roasting the alpha-alumina carrier precursor mixture obtained in the step III to obtain the alpha-alumina carrier.
14. The method for producing an α -alumina carrier according to claim 13, wherein the α -alumina powder accounts for 0.1% to 40.0% of the total mass of the solid mixture.
15. The method for producing an α -alumina carrier according to claim 14, wherein the α -alumina powder accounts for 1.0% to 30.0% of the total mass of the solid mixture.
16. The method for producing an α -alumina carrier according to claim 13, wherein the alumina trihydrate is gibbsite and/or bayerite; the mass of the aluminum oxide trihydrate accounts for 5.0-85.0% of the total mass of the solid mixture.
17. The method for preparing an α -alumina carrier according to claim 16, wherein the alumina trihydrate accounts for 20.0% -80.0% of the total mass of the solid mixture.
18. The method for preparing an α -alumina carrier according to claim 13, wherein the pseudo-boehmite accounts for 2.0-75.0% of the total mass of the solid mixture.
19. The method for preparing an α -alumina carrier according to claim 18, wherein the pseudo-boehmite accounts for 10.0% -60.0% of the total mass of the solid mixture.
20. The method for producing an α -alumina carrier according to claim 13, wherein the fluorine-containing compound is selected from one or more of hydrogen fluoride, aluminum fluoride, ammonium fluoride, magnesium fluoride, lithium fluoride, and cryolite; the mass of the fluorine-containing compound accounts for 0.01% -20.0% of the total mass of the solid mixture.
21. The method for preparing an α -alumina carrier according to claim 20, wherein the fluorine-containing compound accounts for 0.1% -10.0% of the total mass of the solid mixture.
22. The method for producing an α -alumina carrier according to claim 13, wherein the alkaline earth metal compound is selected from one or more of oxides, sulfates, nitrates and oxalates of calcium, strontium and barium; the mass of the alkaline earth metal compound accounts for 0.01% -6.00% of the total mass of the solid mixture.
23. The production method of an α -alumina carrier according to claim 22, wherein the mass of the alkaline earth metal compound is 0.01% -3.00% of the total mass of the solid mixture.
24. The method for producing an α -alumina carrier according to claim 13, wherein the aqueous binder solution is at least one selected from the group consisting of aqueous citric acid solution, aqueous nitric acid solution, aqueous formic acid solution, aqueous acetic acid solution, aqueous propionic acid solution and aqueous hydrochloric acid solution, and wherein the mass ratio of binder to water in the aqueous binder solution is 1: 0.2-10.
25. The method for preparing an α -alumina carrier according to any one of claims 13 to 24, wherein the calcination temperature is 1100 to 1600 ℃ and the time is 0.5 to 30 hours.
26. An α -alumina support produced by the production process of any one of claims 13 to 25.
27. The method of claim 26An alpha-alumina support, wherein the alpha-alumina support has the following characteristics: the specific surface area is 1.0-50.0 m 2 /g; the water absorption rate is more than or equal to 30 percent; the crushing strength is 30 to 300N/grain.
28. The α -alumina support of claim 27, wherein the α -alumina support has the following characteristics: the specific surface area is 1.1-10.0 m 2 /g; the water absorption rate is 40% -70%.
29. A silver catalyst comprising the α -alumina support of any one of claims 1-12 and 26-28 and deposited thereon a catalytically effective amount of silver, optionally an alkali metal promoter and/or alkaline earth metal promoter, and optionally a rhenium promoter and co-promoters thereof.
30. Use of the α -alumina support of any one of claims 1-12 and 26-28 and/or the silver catalyst of claim 29 in the epoxidation of an olefin.
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| WO2009084736A1 (en) * | 2007-12-27 | 2009-07-09 | Nippon Steel Corporation | Process for production of catalyst for use in the reforming of tar-containing gas, method for reforming of tar, and method for regeneration of catalyst for use in the reforming of tar-containing gas |
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