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    • 专利摘要:

    公开号:NL2007510A
    申请号:NL2007510
    申请日:2011-09-30
    公开日:2012-04-02
    发明作者:Wei Lin；Zhiqiang Tang；Jinbing Li；Jianshe Chen；Zhixiang Zhang；Qiang Lin；Jun Jiang；Shuyuan Cao；Qian Xue；Shujuan Wang
    申请人:China Petroleum & Chemical；Beijing Res Inst Chem Ind；
    IPC主号:
    专利说明:

    Title: An alumina support for silver catalyst, its preparation and its useField of the Invention
    The present invention relates to a support for silver catalyst, its preparationand its use. Specifically, the present invention an alumina support for silvercatalyst, a process for preparing said alumina support, a silver catalyst madefrom said alumina support, and a use of said silver catalyst in the productionof ethylene oxide by the oxidization of ethylene.
    Background of the Invention
    Ethylene is oxidized under the action of the silver catalyst to mainly produceethylene oxide, which is accompanied by the side reaction to produce carbondioxide and water. The main technical properties of the silver catalyst includeactivity, selectivity and stability. The activity is reflected by the reactiontemperature at which ethylene oxide is produced with a certain reaction load.The lower the reaction temperature is, the higher the catalyst activity is. Theselectivity means the ratio of the mole of ethylene that converts to ethyleneoxide to the total mole of ethylene that takes part in the reaction. The stabilityis reflected by the rate at which the activity or selectivity drops. The lower thedropping rate is, the better the catalyst stability is. The silver catalyst havinghigh activity, high selectivity and good stability during the production ofethylene oxide by the oxidization of ethylene can improve the economicalbenefit remarkably. Thus, it is a main research object of the silver catalyst tomake a silver catalyst having high activity, high selectivity and good stability.The property of the silver catalyst has a great relation with the property of thesupport used in the silver catalyst preparation and the preparation method ofthe support besides the composition of the catalyst and the preparationmethod of the catalyst.
    The silver catalyst preparation method in the prior art comprises the steps ofpreparing porous support such as alumina and applying active componentsand promoters onto said porous support.
    It is an important research aspect to add some components to alumina supportto modify the support so as to improve the silver catalyst property. In thisconnection, alkaline-earth metal oxides or other salt compounds are added tothe support.
    US4428863 discloses a small amount of binder such as barium aluminate orbarium silicate is used in the production of the alumina support having a highpurity and a low surface area. It is alleged that the crushing strength and thewear resistance of the support can be improved. The prepared support has aspecific surface area of less than 0.3m2/g, as well as low activity and lowselectivity.
    US5384302 alleges that the pre-treatment of alpha-alumina to reduce Na, K,Ca and A1 ion contents in the support can improve the crushing strength andthe wear resistance of the support.
    US5739075 discloses a promoting-amount of rare-earth metal and apromoting-amount of another metal salt (alkaline-earth metal or Group VIIItransition metal) is pre-doped on the surface of alumina support, followed bycalcination, and then the treated support is used to produce the silver catalyst.The evaluation result shows that the dropping rate of the catalyst is lowerthan that of the catalyst without the pre-doping treatment.
    Fluoride is a mineralizing agent and widely used in the production of aluminasupport.
    CN1034678A discloses mixing appropriate sizes and amounts of trihydratealpha-alumina and pseudo-boehmite with carbonaceous material, fluxingagent, fluoride, binder and water, kneading into shape, drying, and calciningto produce the alpha-alumina support. The support has a specific surface areaof 0.2-2 m2/g. Pores with the radii of more than 30 pm comprise 25-10% of thetotal pores. The support is impregnated with silver compound and promoters, dried and activated to be used in the production of ethylene oxide by theoxidation of ethylene with a selectivity as high as 83-84%.
    CN101007287A discloses mixing certain sizes of trihydrate alpha-alumina andpseudo-boehmite with certain amounts of burnout carbonaceous material,fluxing agent, fluoride, and optional heavy alkaline-earth metal compoundhomogenously, followed by adding binder and water, kneading homogenously,extruding into shape, drying, and calcining to produce the alpha-aluminasupport. The support has a specific surface area of 0.2-2 m2/g, a pore volume of0.35-0.85 ml/g, water absorption of > 30%, and a crushing strength of 30-120N/particle. This support is impregnated with a solution of silver-aminecomplex, alkali metal compound and alkaline-earth metal compound, driedand activated to produce a silver catalyst useful for the production of ethyleneoxide by the oxidation of ethylene.
    CN1634652A discloses a process for preparing the support without using apore-forming agent. In that process, trihydrate alpha-alumina is directlymixed in a certain proportion with pseudo-boehmite, fluxing agent, andfluoride homogenously, added binder and water, kneaded homogenously,extruded into shape, dried, and calcined to produce the alpha-alumina support.The support has a specific surface area of 0.2-2.0 m2/g, a pore volume of 0.35-0.85 ml/g, water absorption of > 30%, and a crushing strength of 20-90N/particle. This support is impregnated with a solution of silver-aminecomplex, alkali metal compound and alkaline-earth metal compound, driedand activated to produce a silver catalyst useful for the production of ethyleneoxide by the oxidation of ethylene.
    Albeit the above prior arts suggest adding alkaline-earth metal compound andfluoride to alumina starting material so as to modify alumina support andfurther to produce the catalyst with good activity and selectivity, there is still acontinuous demand for the alumina support having better properties.According to the present invention, a potassium melt technology is adopted to prepare an alumina support, from which a silver catalyst with a higherselectivity can be made.
    Summary of the Invention
    In view of the above-mentioned prior art circumstances, the present inventorshave made deep researches in the field of the silver catalyst and its aluminasupport, and surprisingly found that an alumina support can be prepared bythe potassium melt technology, and a silver catalyst with a higher selectivitycan be made from this alumina support. Specifically, an appropriate amount ofpotassium compound is added to alumina starting material so as to form amelt with low melting point during the calcination of the support and achievethe liquid-phase calcination. Thus, the property of the alumina support isimproved, and a higher selectivity can be obtained with the silver catalystmade from the alumina support.
    Therefore, an object of the present invention is to provide a novel support forthe silver catalyst. The silver catalyst made from the support has shown anexcellent selectivity during the production of ethylene oxide by the oxidation ofethylene.
    Another object of the present invention is to provide a process for preparingthe above-mentioned support.
    Another object of the present invention is to provide a silver catalyst preparedfrom the above-mentioned support.
    Another object of the present invention is to provide a use of the above-mentioned silver catalyst in the production of ethylene oxide by the oxidationof ethylene.
    Specifically, the present invention provides the following technical solutions.According to the first aspect of the present invention, it provides an alpha-alumina support, which is characterized by a specific surface area of 0.2-2.0m2/g; a water absorption of not lower than 30%; a pore volume of 0.30-0.85 ml/g; and a potassium compound content, based on the weight of support andcalculated as potassium element, of 0.001-2.0%.
    In an embodiment according to the first aspect of the present invention, saidalpha-alumina support is characterized by a specific surface area of 0.2-2.0m2/g; a water absorption of not lower than 30%; a pore volume of 0.30-0.85ml/g; a potassium compound content, based on the weight of support andcalculated as potassium element, of 0.001-2.0%; and a heavy alkaline-earthmetal compound content, based on the weight of support and calculated asalkaline-earth metal, of 0.0-2.0%.
    According to the second aspect of the present invention, it provides a processfor preparing an alpha-alumina support, comprising the following steps: I) preparing a mixture of a) based on the total weight of the solids in the mixture, 5-90% by weight oftrihydrate alpha-alumina; b) based on the total weight of the solids in the mixture, 5-90% by weight ofpseudo-boehmite; c) based on the total weight of the solids in the mixture, 0.01-3.0% by weight offluoride mineralizing agent; d) based on the total weight of the solids in the mixture, 0.01-3.0% by weight ofpotassium compound; e) based on the total weight of the solids in the mixture, 0-2.0% by weight ofheavy alkaline-earth metal compound; f) based on the total weight of components a) to e), 10-45% by weight of binderdifferent from components c) to e); and g) an appropriate amount of water; wherein the total weight of the solids in the mixture means the total weight ofcomponents (a), (b), (c), (d) and (e); the total amount of all solid components in the above mixture is 100% byweight, when the above-mentioned mixture contains potassium fluoride, potassiumfluoride may be present in such an amount that potassium fluoride can bedivided into two parts, one part is regarded as fluoride mineralizing agent, theother part is regarded as potassium compound, provided that both the amountof fluoride mineralizing agent and the amount of potassium compound meetthe limitations to the amounts of components (c) and (d);when the above-mentioned mixture contains heavy alkaline-earth metalfluoride, heavy alkaline-earth metal fluoride may be present in such anamount that heavy alkaline-earth metal fluoride can be divided into two parts,one part is regarded as fluoride mineralizing agent, the other part is regardedas heavy alkaline-earth metal compound, provided that both the amount offluoride mineralizing agent and the amount of heavy alkaline-earth metalcompound meet the limitations to the amounts of components (c) and (e); II) kneading the mixture obtained in the step (I) homogenously and extrudinginto shape to give shaped bodies; III) drying the shaped bodies obtained in the step (II), and then calcining themto the alpha-alumina support; and IV) optionally, water-washing the support obtained in the step (III).
    In an embodiment according to the second aspect of the present invention, thefluoride mentioned in the step (I) as component (c) is inorganic fluoride,preferably one or more of hydrogen fluoride, aluminum fluoride, ammoniumfluoride, magnesium fluoride and cryolite, more preferably ammoniumfluoride.
    In another embodiment according to the second aspect of the presentinvention, the potassium compound mentioned in the step (I) as component (d)is inorganic acid salt, organic acid salt, hydroxide or mixture thereof ofpotassium, preferably one or more of potassium nitrate, potassium fluoride,potassium nitrite and potassium carbonate, more preferably potassium nitrate.In another embodiment according to the second aspect of the presentinvention, the heavy alkaline-earth metal compound mentioned in the step (I) as component (e) is selected from oxide, sulfate, acetate, nitrate, carbonate andoxalate of strontium and barium, preferably barium oxide, barium sulfate,barium nitrate, barium carbonate, or a mixture thereof.
    In another embodiment according to the second aspect of the presentinvention, the binder mentioned in the step (I) as component (f) is an acid,preferably an aqueous nitric acid solution, wherein the volume ratio of nitricacid to water is 1:1.25-1:10, preferably 1:2-1:4.
    In another embodiment according to the second aspect of the presentinvention, in the step (I), based on the total weight of the solids in the mixtureprepared in the step (I), the amount of component (a) is 15-85% by weight, theamount of component (b) is 10-80% by weight, the amount of component (c) is0.1-2.5% by weight, the amount of component (d) is 0.1-2.5% by weight, theamount of component (e) is 0-1.0% by weight, and, based on the total weight ofcomponents (a) to (e), the amount of component (f) is 10-35% by weight;preferably, based on the total weight of the solids in the mixture prepared inthe step (I), the amount of component (a) is 35-82% by weight, the amount ofcomponent (b) is 15-62% by weight, the amount of component (c) is 1.2-2.0% byweight, the amount of component (d) is 0.3-1.2% by weight, the amount ofcomponent (e) is 0-0.5% by weight, and, based on the total weight ofcomponents (a) to (e), the amount of component (f) is 10-25% by weight;more preferably, based on the total weight of the solids in the mixtureprepared in the step (I), the amount of component (a) is 65-82% by weight, theamount of component (b) is 15-32% by weight, the amount of component (c) is1.2-2.0% by weight, the amount of component (d) is 0.4-1.0% by weight, theamount of component (e) is 0-0.5% by weight, and, based on the total weight ofcomponents (a) to (e), the amount of component (f) is 10-25% by weight;further more preferably, based on the total weight of the solids in the mixtureprepared in the step (I), the amount of component (a) is 66.5-82% by weight,the amount of component (b) is 15-30% by weight, the amount of component (c)is 1.2-2.0% by weight, the amount of component (d) is 0.4-1.0% by weight, the amount of component (e) is 0-0.5% by weight, and, based on the total weight ofcomponents (a) to (e), the amount of component (f) is 10-25% by weight;still further more preferably, based on the total weight of the solids in themixture prepared in the step (I), the amount of component (a) is 66.5-82% byweight, the amount of component (b) is 15-30% by weight, the amount ofcomponent (c) is 1.2-2.0% by weight, the amount of component (d) is 0.4-1.0%by weight, the amount of component (e) is 0.2-0.5% by weight, and, based onthe total weight of components (a) to (e), the amount of component (f) is 10-25%by weight; wherein the total weight of the solids in the mixture means the total weight ofcomponents (a), (b), (c), (d) and (e); wherein the total amount of all solid components in the mixture prepared inthe step (I) is 100% by weight, when the above-mentioned mixture contains potassium fluoride, potassiumfluoride is present in such an amount that potassium fluoride can be dividedinto two parts, one part is regarded as fluoride mineralizing agent, the otherpart is regarded as potassium compound, provided that both the amount offluoride mineralizing agent and the amount of potassium compound meet thelimitations to the amounts of components (c) and (d); when the above-mentioned mixture contains heavy alkaline-earth metal fluoride, heavyalkaline-earth metal fluoride is present in such an amount that heavyalkaline-earth metal fluoride can be divided into two parts, one part isregarded as fluoride mineralizing agent, the other part is regarded as heavyalkaline-earth metal compound, provided that both the amount of fluoridemineralizing agent and the amount of heavy alkaline-earth metal compoundmeet the limitations to the amounts of components (c) and (e).
    According to the third aspect of the present invention, the present inventionprovides a silver catalyst useful for producing ethylene oxide by the oxidationof ethylene, wherein said catalyst comprises the alpha-alumina support prepared according to the second aspect of the present invention or the alpha-alumina support according to the first aspect of the present invention, andsilver deposited thereon, an optional alkali metal promoter, an optionalalkaline-earth metal promoter, and an optional rhenium promoter andoptionally its co-promoter, wherein calculated on silver atom, silver is present in the silver catalyst in anamount of 1-40%, preferably 5-25%, based on the total weight of the silvercatalyst, wherein calculated on alkali metal atom, the optional alkali metal promoter ispresent in the silver catalyst in an amount of 0-2000 ppm, preferably 5-2000ppm, more preferably 5-1500 ppm, based on the total weight of the silvercatalyst, wherein calculated on rhenium atom, the optional rhenium promoter ispresent in the silver catalyst in an amount of 0-2000 ppm, preferably 10-2000ppm, more preferably 100-1000 ppm, based on the total weight of the silvercatalyst, wherein calculated on alkaline-earth metal atom, the optional alkaline-earthmetal promoter is present in the silver catalyst in an amount of 0-10000 ppm,preferably 0-8000 ppm, based on the total weight of the silver catalyst.
    In an embodiment according to the third aspect of the present invention, saidsilver catalyst is prepared by the method comprising the following steps: 1) Impregnating the alpha-alumina support prepared according to the secondaspect of the present invention or impregnating the alpha-alumina supportaccording to the first aspect of the present invention with a solution containingsufficient amounts of a silver compound, an organic amine, an optional alkalimetal promoter, an optional alkaline-earth metal promoter, and an optionalrhenium promoter and optionally its co-promoter; 2) Filtering the impregnation solution; and 3) Activating the support obtained in the step (2) in an oxygen-containing gasto produce the silver catalyst.
    In another embodiment according to the third aspect of the present invention,the silver compound is silver oxide, silver nitrate and/or silver oxalate, and thesilver compound is used in such an amount that calculated on silver atom,silver is present in the silver catalyst in an amount of 1-40%, preferably 5-25%,based on the total weight of the silver catalyst; the alkali metal promoter is one or more of lithium, sodium, potassium,rubidium and cesium compounds, preferably cesium nitrate, lithium nitrateand/or potassium hydroxide, more preferably cesium nitrate, and the alkalimetal promoter is used in such an amount that calculated on alkali metalatom, the alkali metal promoter is present in the silver catalyst in an amountof 0-2000 ppm, preferably 5-2000 ppm, more preferably 5-1500 ppm, based onthe total weight of the silver catalyst; the rhenium promoter is one or more of rhenium oxide, perrhenic acid, cesiumperrhenate and ammonium perrhenate, preferably ammonium perrhenate,and the rhenium promoter is used in such an amount that calculated onrhenium atom, the rhenium promoter is present in the silver catalyst in anamount of 0-2000 ppm, preferably 10-2000 ppm, more preferably 100-1000ppm, based on the total weight of the silver catalyst; andthe alkaline-earth metal promoter is one or more of magnesium, calcium,strontium and barium compounds, preferably barium compound and/orstrontium compound, such as one or more of oxide, oxalate, sulfate, acetateand nitrate of magnesium, calcium, strontium and barium, and the alkaline-earth metal promoter is used in such an amount that calculated on alkaline-earth metal atom, the alkaline-earth metal promoter is present in the silvercatalyst in an amount of 0-10000 ppm, preferably 0-8000 ppm, based on thetotal weight of the silver catalyst.
    In another embodiment according to the third aspect of the present invention,the activating in the step (3) is conducted in air or a nitrogen-oxygen mixed gaswith oxygen content of 21 vol% or less.
    In another embodiment according to the third aspect of the present invention,in the step (3), the activating is conducted at a temperature of 180-700°C,preferably 200-500°C for 1-120 mins, preferably 2-60 mins.
    According to the fourth aspect of the present invention, the present inventionprovides a use of the silver catalyst according to the third aspect of the presentinvention to produce ethylene oxide by the oxidation of ethylene.
    These aspects and other objects, features and advantages of the presentinvention will be more apparent upon reading the specification.
    Detailed Description of the Invention
    According to one aspect of the present invention, the present inventionprovides a process for preparing alpha-alumina support for silver catalystuseful for producing ethylene oxide by the oxidation of ethylene, wherein saidprocess comprises the following steps: I) preparing a mixture of a) based on the total weight of the solids in the mixture, 5-90% by weight oftrihydrate alpha-alumina; b) based on the total weight of the solids in the mixture, 5-50% by weight ofpseudo-boehmite; c) based on the total weight of the solids in the mixture, 0.01-3.0% by weight offluoride mineralizing agent; d) based on the total weight of the solids in the mixture, 0.01-3.0% by weight ofpotassium compound; e) based on the total weight of the solids in the mixture, 0-2.0% by weight ofheavy alkaline-earth metal compound; f) based on the total weight of components a) to e), 10-45% by weight of binderdifferent from components c) to e); and g) an appropriate amount of water; the total amount of all solid components in the above mixture is 100% byweight, when the above-mentioned mixture contains potassium fluoride, potassiumfluoride is present in such an amount that potassium fluoride can be dividedinto two parts, one part is regarded as fluoride mineralizing agent, the otherpart is regarded as potassium compound, provided that both the amount offluoride mineralizing agent and the amount of potassium compound meet thelimitations to the amounts of components (c) and (d);when the above-mentioned mixture contains heavy alkaline-earth metalfluoride, heavy alkaline-earth metal fluoride is present in such an amount thatheavy alkaline-earth metal fluoride can be divided into two parts, one part isregarded as fluoride mineralizing agent, the other part is regarded as heavyalkaline-earth metal compound, provided that both the amount of fluoridemineralizing agent and the amount of heavy alkaline-earth metal compoundmeet the limitations to the amounts of components (c) and (e); II) kneading the mixture obtained in the step (I) homogenously and extrudinginto shape to give shaped bodies; III) drying the shaped bodies obtained in the step (II), and then calcining themto the alpha-alumina support; and IV) optionally, water-washing the support obtained in the step (III).
    According to one aspect of the present invention, the present inventionprovides a process for preparing alpha-alumina support for silver catalystuseful for producing ethylene oxide by the oxidation of ethylene, wherein saidprocess comprises the following steps: I) preparing a mixture of a) based on the total weight of the solids in the mixture, 5-90% by weight oftrihydrate alpha-alumina; b) based on the total weight of the solids in the mixture, 5-90% by weight ofpseudo-boehmite; c) based on the total weight of the solids in the mixture, 0.01-3.0% by weight offluoride mineralizing agent; d) based on the total weight of the solids in the mixture, 0.01-3.0% by weight ofpotassium compound; e) based on the total weight of the solids in the mixture, 0-2.0% by weight ofheavy alkaline-earth metal compound; f) based on the total weight of components a) to e), 10-45% by weight of binderdifferent from components c) to e); and g) an appropriate amount of water; the total amount of all solid components in the above mixture is 100% byweight, when the above-mentioned mixture contains potassium fluoride, potassiumfluoride is present in such an amount that potassium fluoride can be dividedinto two parts, one part is regarded as fluoride mineralizing agent, the otherpart is regarded as potassium compound, provided that both the amount offluoride mineralizing agent and the amount of potassium compound meet thelimitations to the amounts of components (c) and (d);when the above-mentioned mixture contains heavy alkaline-earth metalfluoride, heavy alkaline-earth metal fluoride is present in such an amount thatheavy alkaline-earth metal fluoride can be divided into two parts, one part isregarded as fluoride mineralizing agent, the other part is regarded as heavyalkaline-earth metal compound, provided that both the amount of fluoridemineralizing agent and the amount of heavy alkaline-earth metal compoundmeet the limitations to the amounts of components (c) and (e); II) kneading the mixture obtained in the step (I) homogenously and extrudinginto shape to give shaped bodies; III) drying the shaped bodies obtained in the step (II), and then calcining themto the alpha-alumina support; and IV) optionally, water-washing the support obtained in the step (III).
    According to the present invention, the total weight of the solids in the mixturemeans the total weight of components (a), (b), (c), (d) and (e).
    In order to prepare the alpha-alumina support of the present invention, it isnecessary to use trihydrate alpha-alumina, i.e., component (a). Based on thetotal weight of the solids in the mixture, i.e., based on the total weight of thesolids in the mixture prepared in the step (I), trihydrate alpha-alumina isusually used in an amount of 5-90% by weight, preferably 15-80% by weight,more preferably 35-80% by weight, particularly preferably 65-80% by weight.In one embodiment, the used amount of component (a) is 5-90% by weight, or15-85% by weight, or 35-82% by weight, or 65-82% by weight, or 66.5-82% byweight, or 66.5-82% by weight, based on the total weight of the solids in themixture.
    Based on the total weight of the solids in the mixture, i.e., based on the totalweight of the solids in the mixture prepared in the step (I), pseudo-boehmite,as component (b), is usually used in an amount of 5-50% by weight, preferably10-40% by weight, more preferably 15-40% by weight, particularly preferably15-30% by weight.
    In one embodiment, the used amount of component (b) is 5-90% by weight, or10-80% by weight, or 15-62% by weight, or 15-32% by weight, or 15-30% byweight, based on the total weight of the solids in the mixture.
    During the preparation of the alpha-alumina support of the present invention,the fluoride is added as component (c) so as to accelerate the alumina crystalform conversion and therefore used as mineralizing agent. The fluoride used inthe present invention is an inorganic fluoride, comprising hydrogen fluoride,ammonium fluoride, aluminum fluoride, magnesium fluoride, cryolite and thelike, preferably one or more of hydrogen fluoride, aluminum fluoride,ammonium fluoride, magnesium fluoride and cryolite, more preferablyammonium fluoride. For the purpose of the present invention, based on thetotal weight of the solids in the mixture, i.e., based on the total weight of thesolids in the mixture prepared in the step (I), the fluoride is usually added inan amount of 0.01-3.0% by weight, preferably 0.1-2.5% by weight, particularlypreferably 1.2-2.0% by weight.
    The potassium compound is added as component (d) so as to form a melt withlow melting point during the calcination of the support and achieve the liquid-phase calcination. Thus, the property of the alumina support is improved, anda higher selectivity can be obtained with the silver catalyst made from thealumina support. The potassium compound used in the present invention ispotassium-containing inorganic or organic compound, including inorganic acidsalt, organic acid salt and hydroxide of potassium and the like, for example,potassium nitrate, potassium nitrite, potassium carbonate, potassiumbicarbonate, potassium fluoride, potassium sulfate, potassium stearate,potassium silicate, potassium oxalate, potassium acetate, potassiumhydroxide, potassium meta-aluminate and the like, preferably one or more ofpotassium nitrate, potassium fluoride, potassium carbonate and potassiumnitrite, more preferably potassium nitrate. For the purpose of the presentinvention, based on the total weight of the solids in the mixture, i.e., based onthe total weight of the solids in the mixture prepared in the step (I), thepotassium compound is usually added in an amount of 0.01-3.0% by weight,preferably 0.1-2.5% by weight, more preferably 0.3-1.2% by weight,particularly preferably 0.4-1.0% by weight. When the above-mentionedmixture contains potassium fluoride, potassium fluoride is present in such anamount that potassium fluoride can be divided into two parts, one part isregarded as fluoride mineralizing agent, the other part is regarded aspotassium compound, provided that both the amount of fluoride mineralizingagent and the amount of potassium compound meet the limitations to theamounts of components (c) and (d).
    During the preparation of the alpha-alumina support of the present invention,the heavy alkaline-earth metal compound, i.e., component (e), can beoptionally used in the step (I) for the purpose of modifying the property of thesupport. The heavy alkaline-earth metal compound is selected from compoundsof the elements of the group IIA of the periodic table, for example, strontiumand/or barium compound, e.g. oxide, sulfate, acetate, nitrate, carbonate and oxalate of strontium and/or barium. It is particularly preferable to use bariumoxide, barium sulfate, barium nitrate, barium carbonate, or a mixture thereofas the heavy alkaline-earth metal compound. Based on the total weight of thesolids in the mixture, i.e., based on the total weight of the solids in the mixtureprepared in the step (I), the heavy alkaline-earth metal compound, particularlystrontium and/or barium compound is added in an amount of 0-2.0%,preferably 0-1.0% by weight, particularly preferably 0-0.5% by weight. Whenthe above-mentioned mixture contains heavy alkaline-earth metal fluoride,heavy alkaline-earth metal fluoride is present in such an amount that heavyalkaline-earth metal fluoride can be divided into two parts, one part isregarded as fluoride mineralizing agent, the other part is regarded as heavyalkaline-earth metal compound, provided that both the amount of fluoridemineralizing agent and the amount of heavy alkaline-earth metal compoundmeet the limitations to the amounts of components (c) and (e).
    In one embodiment, the used amount of component (e) is 0-2.0% by weight, or0-1.0% by weight, or 0-0.5% by weight, or 0.2-0.5% by weight, based on thetotal weight of the solids in the mixture. When the above-mentioned mixturecontains heavy alkaline-earth metal fluoride, heavy alkaline-earth metalfluoride is present in such an amount that heavy alkaline-earth metal fluoridecan be divided into two parts, one part is regarded as fluoride mineralizingagent, the other part is regarded as heavy alkaline-earth metal compound,provided that both the amount of fluoride mineralizing agent and the amountof heavy alkaline-earth metal compound meet the limitations to the amountsof components (c) and (e).
    During the preparation of the alpha-alumina support of the present invention,a binder can be added as component (f). The binder and pseudo-boehmite inthe mixture form an alumina sol, which bind components in the mixturetogether to form an extrudable paste. The binder comprises an acid, such asnitric acid, formic acid, acetic acid, propionic acid, hydrochloric acid and thelike. Alternatively, the acid and pseudo-boehmite can be replaced by alumina sol. In case of using the acid as binder, it is preferable to use an aqueous nitricacid solution, wherein the volume ratio of nitric acid to water is 1:1.25-1:10,preferably 1:2-1:4. For the purpose of the present invention, the binder isusually added in an amount of, based on the total weight of components (a) to(e), 10-45% by weight, preferably 10-35% by weight, particularly preferably 10-25% by weight.
    In one preferable embodiment for preparing the alpha-alumina support of thepresent invention, in the step (I), based on the total weight of the solids in themixture, i.e., based on the total weight of the solids in the mixture prepared inthe step (I), the amount of component (a) is 15-80% by weight, preferably 35-80% by weight, the amount of component (b) is 10-40% by weight, preferably15-40% by weight, the amount of component (c) is 0.1-2.5% by weight,preferably 1.2-2.0% by weight, the amount of component (d) is 0.1-2.5% byweight, preferably 0.3-1.2% by weight, the amount of component (e) is 0-1.0%by weight, preferably 0-0.5% by weight, and based on the total weight ofcomponents (a) to (e), the amount of component (f) is 10-35% by weight,preferably 10-25% by weight, wherein the total amount of all solid componentsin the mixture prepared in the step (I) is 100% by weight, when the above-mentioned mixture contains potassium fluoride, potassium fluoride is presentin such an amount that potassium fluoride can be divided into two parts, onepart is regarded as fluoride mineralizing agent, the other part is regarded aspotassium compound, provided that both the amount of fluoride mineralizingagent and the amount of potassium compound meet the limitations to theamounts of components (c) and (d); when the above-mentioned mixturecontains heavy alkaline-earth metal fluoride, heavy alkaline-earth metalfluoride is present in such an amount that heavy alkaline-earth metal fluoridecan be divided into two parts, one part is regarded as fluoride mineralizingagent, the other part is regarded as heavy alkaline-earth metal compound,provided that both the amount of fluoride mineralizing agent and the amount of heavy alkaline-earth metal compound meet the limitations to the amountsof components (c) and (e).
    In one particularly preferable embodiment for preparing the alpha-aluminasupport of the present invention, in the step (I), based on the total weight ofthe solids in the mixture, i.e., based on the total weight of the solids in themixture prepared in the step (I), the amount of component (a) is 65-80% byweight, the amount of component (b) is 15-30% by weight, the amount ofcomponent (c) is 1.2-2.0% by weight, the amount of component (d) is 0.4-1.0%by weight, the amount of component (e) is 0-0.5% by weight, and based on thetotal weight of components (a) to (e), the amount of component (f) is 10-25% byweight, wherein the total amount of all solid components in the mixtureprepared in the step (I) is 100% by weight, when the above-mentioned mixturecontains potassium fluoride, potassium fluoride is present in such an amountthat potassium fluoride can be divided into two parts, one part is regarded asfluoride mineralizing agent, the other part is regarded as potassiumcompound, provided that both the amount of fluoride mineralizing agent andthe amount of potassium compound meet the limitations to the amounts ofcomponents (c) and (d); when the above-mentioned mixture contains heavyalkaline-earth metal fluoride, heavy alkaline-earth metal fluoride is present insuch an amount that heavy alkaline-earth metal fluoride can be divided intotwo parts, one part is regarded as fluoride mineralizing agent, the other part isregarded as heavy alkaline-earth metal compound, provided that both theamount of fluoride mineralizing agent and the amount of heavy alkaline-earthmetal compound meet the limitations to the amounts of components (c) and (e).After kneading the mixture in the step (I), in general, a paste is obtained. It isusually advantageous for the present invention to firstly mix components (a),(b) and (e) homogenously and charge into the kneader, and then addcomponents (c), (d), (f) and (g) to knead into an extrudable paste. The obtainedpaste is extruded into shape to produce shaped bodies. The shaped bodies canbe dried to a moisture content of 10wt% or less. The drying temperature can be 80-120°C. The drying time can be controlled depending on the moisturecontent, for example, the drying time is 1-24 hours. The obtained shapedbodies can be in a form of ring, sphere, column or multihole column or the like.After drying, the shaped bodies are generally calcined at a temperature of 900-1600°C, preferably 1100-1400°C for not less than 1 hour, preferably 3-8 hours.Substantially all of alumina, for example, more than 90% of alumina can beconverted to alpha-alumina by the calcination so as to obtain the alpha-alumina support.
    In one preferable embodiment for preparing the alpha-alumina support of thepresent invention, after the step (III), the support obtained in the step (III) iswater-washed. The water-washing can be conducted with distilled water ordeionized water or other water, preferably deionized water. The water-washingcan be done with ultrasonic technique. After water-washing, the support isdried. For example, in one preferable embodiment for water-washing, thesupport is placed in a vessel containing deionized water, sonically oscillated fora period of time (e.g. 5-60 mins), thereafter stood for a period of time (e.g. 5-30mins), then filtered to remove the aqueous solution, and finally dried in aheated air stream (e.g. the air stream heated to 100-800 °C) to produce thesupport.
    According to another aspect of the present invention, the alpha-aluminasupport prepared by the above-mentioned process is provided, wherein saidsupport has a specific surface area of 0.2-2.0 m2/g; a water absorption of notlower than 30%; a pore volume of 0.30-0.85 ml/g; a potassium compoundcontent, based on the weight of support and calculated as potassium element,of 0.001-2.0%.
    According to the present invention, the specific surface area of the support ismeasured according to the International Standard ISO-9277 by the NitrogenGas Physical Adsorption BET Method. For example, the specific surface areaof the support can be measured with Nitrogen Gas Physical AdsorptionInstrument NOVA2000e (Quantachrome Corp., USA).
    According to the present invention, the pore volume of the support is measuredby the mercury porosimetry. For example, the pore volume of the support canbe measured with AutoPore9510-type Mercury Porosimeter (MicromeriticsInstrument Corp., USA).
    The radial crush strength of the support, for example, can be measured withthe DL II type Particle Strength Tester (manufactured by Dalian Research andDesign Institute of Chemical Industry) by randomly selecting thirty supportsample particles, measuring the radial crush strength for each particle, andthen calculating the average of the radial crush strength.
    The content of the potassium compound in the support can be obtained bycalculation or measurement (for example, X-Ray fluorescence).
    The content of the alkaline-earth metal in the support can be obtained bycalculation or measurement (for example, X-Ray fluorescence). The alpha-alumina support produced by the process for preparing the alumina supportaccording to the present invention can be in a conventional form in the art,such as ring, sphere, column, multihole column or the like.
    After obtaining the alpha-alumina support of the present invention, a silvercatalyst can be produced in a manner known by the skilled person in the art orin a conventional manner. For example, the silver catalyst of the presentinvention can be produced by impregnating the above alumina support with asolution containing a silver compound and an organic amine.
    The addition of the active component silver can be accomplished by aconventional impregnation method. For example, the support is impregnatedin a silver-amine complex solution, and then heat-treated after removing aredundant solution by filtration. The used silver compound can be a silverprecursor, such as silver oxide, silver nitrate, and silver oxalate, preferablysilver oxalate. For ensuring the uniform and adequate loading of silver, thesupport is preferably vacuumed in advance, and immediately activated in aflowing air or inert gas such as nitrogen and argon at a temperature of 200-500°C for 2 mins or more after the impregnation and the filtration. For ensuring that the catalyst has a relative high activity, the heat-treatment should beconducted at a temperature not higher than 500 °C. For further improving thecatalyst performance, an alkali metal promoter such as lithium compound,sodium compound, potassium compound, rubidium compound, cesiumcompound or a mixture thereof, an alkaline-earth metal promoter such ascalcium compound, strontium compound, barium compound or a mixturethereof, a rhenium promoter and optionally a rhenium co-promoter, and thelike, can be added to the silver catalyst of the present invention. Thesepromoters can be applied to the support before, during or after the silverimpregnation, or impregnated onto the support after the silver compound hasbeen reduced.
    In one embodiment of the present invention, the process for preparing thesilver catalyst of the present invention comprises the following steps: 1) Impregnating the above alumina support with a solution containingsufficient amounts of a silver compound, an organic amine, an optional alkalimetal promoter, an optional alkaline-earth metal promoter, and an optionalrhenium promoter and optionally its co-promoter; 2) Filtering the impregnation solution; and 3) Activating the support obtained in the step (2) in an oxygen-containing gasto produce the silver catalyst.
    The above silver compound can be any silver compound suitable for preparingthe silver catalyst useful for the production of ethylene oxide. According to thepresent invention, it is preferable to use silver oxide, silver nitrate and/orsilver oxalate. The amount of the silver compound used in the impregnationprocedure should be sufficient so that the finally produced silver catalystcontains 1-40 wt%, preferably 5-25 wt% of silver calculated on the silver atombased on the total weight of the catalyst.
    The above organic amine compound can be any organic amine compoundsuitable for preparing the silver catalyst useful for the production of ethyleneoxide, provided that the organic amine compound has an ability to form a silver-amine complex with the silver compound. According to the presentinvention, it is preferable to use pyridine, butyl amine, ethylene diamine, 1,3-propylene diamine, ethanolamine or a mixture thereof, for example a mixtureof ethylene diamine and ethanolamine.
    In the process for preparing the silver catalyst of the present invention, theoptionally used alkali metal promoter can be lithium compound, sodiumcompound, potassium compound, rubidium compound or cesium compound(such as nitrate, sulfate and hydroxide) or a mixture thereof, preferably thealkali metal promoter is one or more of lithium compound, potassiumcompound and cesium compound, such as cesium nitrate, lithium nitrateand/or potassium hydroxide, especially cesium nitrate. The alkali metalpromoter is favorably added to the impregnation solution in such an amountthat the alkali metal is present in the final catalyst in an amount of 0-2000ppm by weight, preferably 5-2000 ppm by weight, more preferably 5-1500 ppmby weight, calculated on the alkali metal atom.
    In the process for preparing the silver catalyst of the present invention, theoptionally used alkaline-earth metal promoter can be one or more ofmagnesium compound, calcium compound, strontium compound and bariumcompound, such as oxide, oxalate, sulfate, acetate and nitrate of said elements,preferably barium compound and/or strontium compound, such as bariumacetate and/or strontium acetate. The alkaline-earth metal promoter isfavorably added to the impregnation solution in such an amount that thealkaline-earth metal is present in the final catalyst in an amount of 0-10000ppm by weight, preferably 0-8000 ppm by weight, calculated on the alkaline-earth metal atom.
    In the process for preparing the silver catalyst of the present invention, theoptionally used rhenium promoter can be rhenium oxide, perrhenic acid,perrhenate, or a mixture thereof, preferably perrhenic acid and perrhenate,such as perrhenic acid, cesium perrhenate and ammonium perrhenate,particularly preferably ammonium perrhenate. The rhenium promoter is added to the impregnation solution in such an amount that the rhenium metalis present in the final catalyst in an amount of 0-2000 ppm, preferably 10-2000ppm, more preferably 100-1000 ppm, calculated on the rhenium metal atom.When the rhenium promoter is present in the impregnation solution, a co¬promoter of the rhenium promoter can be added to further improve theactivity, the selectivity and the stability of the obtained silver catalyst. The co¬promoter of the rhenium promoter according to the present invention can be acompound of any transitional metal in the Periodic Table, or a mixture oftransitional metal compounds, preferably an oxyacid of an element selectedfrom Groups VIB and VIIB, and a salt thereof, for example, tungstenic acid,sodium tungstate, potassium tungstate, ammonium tungstate, cesiumtungstate, molybdic acid, ammonium molybdate, ammonium metatungstate,and the like. The co-promoter of the rhenium promoter is used in such anamount that the co-promoter of the rhenium promoter is present in the finalcatalyst in an amount of 0-1000 ppm, preferably 0-500 ppm.
    In one preferable embodiment of the process for preparing the silver catalyst ofthe present invention, firstly, a silver compound such as silver oxalate isdissolved into an aqueous solution of organic amine such as pyridine, butylamine, ethylene diamine, 1,3-propylene diamine, ethanolamine or a mixturethereof, into which is added the optional alkali metal promoter, the optionalalkaline-earth metal promoter, and the optional rhenium promoter andoptionally its co-promoter to formulate an impregnation solution. Then thealumina support is impregnated with the obtained impregnation solution,filtered to dryness, and kept in air or a nitrogen-oxygen mixed gas with oxygencontent of 21 vol% or less at 180-700 °C, preferably 200-500 °C for 1-120 mins,preferably 2-60 mins to thermally decompose and activate.
    A silver catalyst can be obtained by the process for preparing the catalyst ofthe present invention, and it can be used in a gas-solid phase catalyticoxidation of ethylene to produce ethylene oxide.
    Therefore, according to yet another aspect of the present invention, the presentinvention provides a silver catalyst prepared according to the above processand useful in a gas-phase catalytic oxidation of ethylene to produce ethyleneoxide, which catalyst contains the alpha-alumina support prepared accordingto the present invention and silver deposited thereon in an amount of 1-40 wt%calculated on silver atom based on the total weight of the silver catalyst, anoptional alkali metal promoter, an optional alkaline-earth metal promoter andan optional rhenium promoter.
    In one preferable embodiment of the silver catalyst of the present invention,the silver catalyst according to the present invention contains the alpha-alumina support prepared according to the present invention and silverdeposited thereon in an amount of 1-40 wt% calculated on silver atom based onthe total weight of the silver catalyst, an alkali metal promoter in an amountof 5-2000 ppm by weight calculated on the alkali metal atom, and a rheniumpromoter in an amount of 10-2000 ppm by weight calculated on the rheniumatom.
    Finally, the present invention also relates to a use of the silver catalystaccording to the present invention in the production of ethylene oxide by theoxidation of ethylene.
    Compared with the prior art, the present invention has the followingadvantage: the alumina support prepared according to the present inventioncan be used to produce a silver catalyst with a higher selectivity for theproduction of ethylene oxide by the catalytic oxidization of ethylene.
    Examples
    The present invention will be illustrated by the following examples, but thescope of the present invention is not limit thereto.
    The catalyst performance evaluation
    The silver catalysts used in the examples of the present invention were testedin a laboratory micro-reactor evaluation apparatus for the catalytic reaction performance. In the micro-reactor evaluation apparatus, the reactor was astainless steel reaction tube having an inner diameter of 4mm. The reactiontube was disposed in a heating jacket. The loading volume of the catalyst was1 mL. The inert filler was disposed in the lower portion so that the catalyst bedwas located in the constant temperature area of the heating jacket.
    The standard evaluation conditions for the catalytic activity and the selectivityused in the present invention were as follows:
    The composition of the reaction gas (mol%):
    Ethylene (C2H4) 28.0+1.0
    Oxygen (O2) 7.4+0.2
    Carbon dioxide (CO2) < 3.0
    Ballast gas(N2) Balance
    Inhibitor 1,2-dichloroethane 0.1 ppm-2.0 ppm
    Reaction pressure 2.1 MPa
    Space velocity 7000/h
    The concentration of ethylene oxide (EO) 2.5 mol%in the effluent from the reactor
    Hour space yield 344 g EO/ml Cat./h
    When the reaction becomes stable and reaches the above reaction conditions,the compositions of the gases at the inlet and the outlet of the reactor werecontinually measured. The measurement results, after applying the volume-shrinkage correction thereto, were used to calculate the selectivity according tothe following formula:
    wherein ΔΕΟ was the ethylene oxide concentration difference between theoutlet and the inlet of the reactor; and Δ002 is the carbon dioxideconcentration difference between the outlet and the inlet of the reactor. Ten ormore sets of experiment data were taken and averaged as the experimentresult of that day.
    The Preparation for SupportExample 1 (Comparative)
    The first part of starting materials of 3725 g trihydrate alpha-alumina, 1095 gpseudo-boehmite and 10 g BaSC>4 was put into a mixer to mix homogenously.The second part of starting materials having the same compositions as theabove was mixed homogenously. Two parts of starting materials were put intoa kneader. 160g NH4F was completely dissolved into 1.90L of a dilutedaqueous nitric acid solution (nitric acid:water=l:3 v/v), added to the kneader toknead into an extrudable paste. Finally, the paste was put into an extruder toextrude into column-like bodies with an outer diameter of 8.0 mm and a lengthof 6.0 mm, and dried at a temperature of 80-120 °C for 2 hours or more untilthe free-water content of the bodies decreased to the level below 10 wt%.
    The dried column-like bodies were put into a natural gas kiln, heated up over aperiod of 18 hours from room temperature to 1250 °C, and kept at thattemperature constantly for 4 hours to obtain an alpha-alumina samplenumbered as Support 1. The relevant physical properties of Support 1 arelisted in Table 1.
    Example 2 (Inventive)
    The first part of starting materials of 3725 g trihydrate alpha-alumina, 1095 gpseudo-boehmite and 10 g BaS04 was put into a mixer to mix homogenously.The second part of starting materials having the same compositions as theabove was mixed homogenously. Two parts of starting materials were put intoa kneader. 160g NH4F and 80 g potassium nitrate were completely dissolvedinto 1.80L of a diluted aqueous nitric acid solution (nitric acid:water=l:3 v/v),added to the kneader to knead into an extrudable paste. Finally, the paste wasput into an extruder to extrude into column-like bodies with an outer diameterof 8.0 mm and a length of 6.0 mm, and dried at a temperature of 80-120 °C for2 hours or more until the free-water content of the bodies decreased to thelevel below 10 wt%.
    The dried column-like bodies were put into a natural gas kiln, heated up over aperiod of 18 hours from room temperature to 1250 °C, and kept at thattemperature constantly for 4 hours to obtain an alpha-alumina samplenumbered as Support 2. The relevant physical properties of Support 2 arelisted in Table 1.
    Example 3 (Inventive) 200 g Support 2 was put into a glass vessel, into which was added 400 gdeionized water, sonically oscillated for 20 mins, thereafter stood for 10 mins,then filtered to remove the aqueous solution, heated in an air stream of 380 °Cfor 3 mins, and cooled to produce Support 3. The relevant physical propertiesof Support 3 are listed in Table 1.
    Table 1: The physical properties of Supports 1-3
    The Preparation for Catalysts 1-3
    To a glass flask with a stirrer were added 48.2 g ethylene diamine, 16.3 gethanolamine and 105.8 g deionized water to give a mixed solution. 108.lg ofsilver oxalate was slowly added to the mixed solution while stirring. Thesolution temperature was maintained at a temperature of below 40°C, andsilver oxalate was dissolved completely. Then 6.01 ml of an aqueous cesiumnitrate solution having a concentration of 0.03995g/ml calculated as thecesium atom weight, 9.26 ml of an aqueous ammonium perrhenate solutionhaving a concentration of 0.0162g/ml calculated as the rhenium atom weight,and 6.40 ml of an aqueous sodium tungstate solution having a concentration of 0.00938g/ml calculated as the tungsten atom weight were successively added.The solution was mixed homogenously to give an impregnation solution foruse.
    Each 20 g of the above prepared Supports 1-3 were placed into glass vesselswhich can be vacuumed, into which were poured the above formulatedimpregnation solutions until the supports were immerged, vacuumed to apressure below lOmmHg, maintained for 10 mins, filtered to remove theredundant solution, then heated in an air stream at 260°C for 3 mins, andcooled to give Silver Catalysts 1-3.
    Table 2: The composition of the silver catalysts (by weight)
    Under the evaluation conditions given in the above section "The catalystperformance evaluation", the Silver Catalysts 1-3 were evaluated for theactivity and selectivity of the catalysts in the micro-reactor evaluationapparatus. The results are shown in Table 3.
    Table 3: Evaluation data for Catalysts 1-3
    It is clear from Table 3 that in comparison with Comparative Silver Catalyst I,the Silver Catalyst 2 made from the support prepared by potassium melttechnology has a higher selectivity. Furthermore, the Silver Catalyst 3, madefrom the Support 3 that was subjected to a subsequent water-washingprocedure, has a better catalytic activity than the Silver Catalyst 2.
    权利要求:
    Claims (15)
    [1]
    An alpha alumina support, which is characterized by a specific surface area of 0.2-2.0 m2 / g; a water absorption of no lower than 30%; a pore volume of 0.30-0.85 ml / g; and a potassium compound content, based on the weight of the carrier and calculated on a potassium element, of 0.001-2.0%.
    [2]
    A process for preparing an alpha alumina carrier, in particular the alpha alumina carrier according to claim 1, comprising the following steps: I) preparing a mixture of a) 5-90% by weight trihydrate alpha alumina, based on of the total weight of the solids in the mixture; b) 5-90% by weight of pseudo-boehmite, based on the total weight of the solids in the mixture; c) 0.01-3.0% by weight of fluoride mineralizing agent, based on the total weight of the solids in the mixture; d) 0.01-3.0% by weight of potassium compound, based on the total weight of the solids in the mixture; e) 0-2.0% by weight heavy alkaline earth metal compound, based on the total weight of the solids in the mixture; f) 10-45% binder by weight different from components c) to e), based on the total weight of components a) to e); and g) an appropriate amount of water; wherein the total weight of the solids in the mixture is the total weight of components (a), (b), (c), (d) and (e), the total weight of all solid components in the above mixture is 100% by weight ; if the above mixture contains potassium fluoride, potassium fluoride is present in such an amount that potassium fluoride can be divided into two parts, one part is considered as a fluoridinising agent, the other part is considered as a potassium compound, with the proviso that both the amount of fluoridinising agent and the amount of potassium compound are adequate to the limits on the amounts of components (c) and (d), if the above-mentioned mixture contains heavy earth alkaline metal fluoride, heavy earth alkaline metal fluoride is present in such an amount that heavy earth alkaline metal fluoride can be divided into two parts, a part is considered as fluoride mineralizing agent the other part is considered a heavy alkaline earth metal compound, with the proviso that both the amount of fluoride mineralizing agent and the amount of heavy alkaline earth metal compound meet the limits on the amounts of components (c) and (e); II) homogeneously kneading the mixture obtained in step (I) and in shape extruding to provide shaped bodies; III) drying the shaped bodies obtained in step (II), and then calcining them into the alpha alumina support; and IV) optionally, wash the carrier obtained in step (III) with water.
    [3]
    The process according to claim 2, wherein the fluoride mentioned in step (I) as component (c) is inorganic fluoride, preferably one or more of hydrogen fluoride, aluminum fluoride, ammonium fluoride, magnesium fluoride and cryolite, more preferably ammonium fluoride.
    [4]
    The process according to claim 2 or 3, wherein the potassium compound mentioned in step (I) as component (d) is inorganic salt of an acid, preferably one or more of potassium nitrate, potassium fluoride, potassium nitrite, potassium carbonate, more preferably potassium nitrate.
    [5]
    The process according to any of claims 2-4, wherein the heavy alkaline earth metal compound mentioned in step (I) is selected as component (e) from oxide, sulfate, acetate, nitrate, carbonate and oxalate of strontium and barium, preferably barium oxide, barium sulfate, barium nitrate, barium carbonate, or a mixture thereof.
    [6]
    The process according to any of claims 2-5, wherein the binder mentioned in step (I) as component (f) is an acid, preferably an aqueous nitrous acid solution, wherein the volume ratio of nitric acid to water is 1: 1.25-1: 10 , preferably 1: 2-1: 4.
    [7]
    The process according to any of claims 2-6, wherein in step (I), based on the total weight of the solids prepared in the mixture step (I), the amount of component (a) is 15-85% by weight, the quantity component (b) is 10-80% by weight, the quantity of component (c) is 0.1-2.5% by weight, the quantity of component (d) is 0.1-2.5% by weight, the quantity of component (e) Is 0-1.0% by weight, and, based on the total weight of components (a) to (e), the amount of component (f) is 10-35% by weight; preferably, based on the total weight of the solids in the mixture prepared in step (I), the amount of component (a) is 35-82% by weight, the amount of component (b) is 15-62% by weight, quantity of component ( c) is 1.2-2.0% by weight, amount of component (d) is 0.3-1.2% by weight, quantity of component (e) is 0-0.5% by weight, and, based on the total weight of components (a) to (e), the quantity component (f) is 10-25% by weight; more preferably, based on the total weight of the solids in the mixture prepared in step (I), the amount of component (a) is 65-82% by weight, the amount of component (b) is 15-32% by weight, amount of component (c) is 1.2-2.0% by weight, amount of component (d) is 0.4-1.0% by weight, quantity of component (e) is 0-0.5% by weight, and, based on the total weight of components (a) to (e), the amount of component (f) is 10-25% by weight; furthermore more preferably, based on the total weight of the solids in the mixture prepared in step (I), the amount of component (a) is 66.5-82% by weight, the amount of component (b) 15-30% by weight is, amount of component (c) is 1.2-2.0% by weight, amount of component (d) is 0.4-1.0% by weight, amount of component (e) is 0-0.5% by weight, and, based on the total weight of components (a) to (e), the amount of component (f) is 10-25% by weight; even more preferably, based on the total weight of the solids in the mixture prepared in step (I), the amount of component (a) is 66.5-82 weight%, the amount of component (b) 15-30 weight %, amount of component (c) is 1.2-2.0 weight%, quantity of component (d) is 0.4-1.0 weight%, quantity of component (e) is 0-0.5 weight%, and , based on the total weight of components (a) to (e), the amount of component (¢) is 10-25% by weight; wherein the total weight of the solids in the mixture means the total weight of components (a), (b), (c), (d) and (e), the total amount of all solid components in the mixture prepared in step ( I) is 100% by weight; if the above mixture contains potassium fluoride, potassium fluoride is present in such an amount that potassium fluoride can be divided into two parts, one part is considered as a fluoridinising agent, the other part is considered as a potassium compound, with the proviso that both the amount of fluoridinising agent and the amount of potassium compound are adequate to the limits on the amounts of components (c) and (d), if the above-mentioned mixture contains heavy earth alkaline metal fluoride, heavy earth alkaline metal fluoride is present in such an amount that heavy earth alkaline metal fluoride can be divided into two parts, a part is considered to be fluoride mineralizing agent, the other part is considered a heavy alkaline earth metal compound, with the proviso that both the amount of fluoride mineralizing agent and the amount of heavy alkaline earth metal compound meet the limits on the amounts of components (c) and (e);
    [8]
    A silver catalyst useful for producing ethylene oxide by the oxidation of ethylene, said catalyst comprising the alpha-alumina support of claim 1, and silver applied thereto, an optional alkali metal promoter, an optional alkaline earth metal promoter, and an optional rhenium promoter and optionally its co-promoter, wherein calculated on silver atom, silver is present in the silver catalyst in an amount of 1-40%, preferably 5-25%, based on the total weight of the silver catalyst, wherein calculated on rhenium atom, the optional rhenium promoter is present in the silver catalyst in an amount of 0-2000 ppm, preferably 10-2000 ppm, more preferably 100-1000 ppm, based on the total weight of the silver catalyst, wherein based on alkaline earth metal atom, the optional alkaline earth metal promoter is present in the silver catalyst in an amount of 0-100000 ppm, preferably 0-8000 ppm, based on the total weight of the silver catalyst.
    [9]
    A method for preparing a silver catalyst according to claim 8, comprising the following steps: 1. impregnating the alpha-alumina support prepared by the process according to claims 2-7 or impregnating the alpha-alumina support according to claim 1 with a solution which contains sufficient amounts of a silver compound, an organic amine, an optional alkali metal promoter, an optional alkaline earth metal promoter, and an optional rhenium promoter and optionally its co-promoter; 2. filtering the impregnation solution; and 3. activating the support obtained in step (2) in an oxygen-containing gas to produce the silver catalyst.
    [10]
    Process according to claim 9, wherein the silver compound is silver oxide, silver nitrate and / or silver oxalate, and the silver compound is used in an amount such that, based on silver atom, silver is present in the silver catalyst in an amount of 1-40%, preferably 5-25 %, based on the total weight of the silver catalyst; the alkali metal promoter is one or more of lithium, sodium, potassium, rubidium and cesium compound, preferably cesium nitrate, lithium nitrate and / or potassium hydroxide, more preferably cesium nitrate, and the alkali metal promoter is used in an amount such that calculated on alkali metal atom, alkali metal promoter is present in the silver catalyst in an amount of 0-2000 ppm, preferably 5-2000 ppm, more preferably 5-1500 ppm, based on the total weight of the silver catalyst; the rhenium promoter is one or more of rhenium oxide, perrhenate and ammonium perrhenate, preferably ammonium perrhenate, and derhenium promoter is used in such an amount that calculated on rhenium atom, the rhenium promoter is present in the silver catalyst in an amount of 0-20000 ppm, preferably 12-2000ppm, preferably more preferably 100-1000 ppm, based on the total weight of the silver catalyst; and the alkaline earth metal promoter is one or more of magnesium, calcium, strontium and barium compounds, preferably barium compound and / or strontium compound, such as one or more of oxide, oxalate, sulfate, acetate and nitrate of magnesium, calcium, strontium and barium, and the alkaline earth metal promoter is used in such an amount that calculated on alkaline earth metal atom, the alkaline earth metal promoter is present in the silver catalyst in an amount of 0-10000 ppm, preferably 0-8000 ppm, based on the total weight of the silver catalyst.
    [11]
    The method according to claim 9 or 10, wherein the activation in step (3) is carried out in air or a nitrogen-oxygen mixed gas with an oxygen content of 21% by volume or less.
    [12]
    A method according to any of claims 9-11, wherein in step (3) deactivation is carried out at a temperature of 180-700 ° C, preferably 200-500 ° C for 1-120 minutes, preferably 2-60 minutes.
    [13]
    A silver catalyst according to claim 8, which is prepared by the process according to any of claims 9-12.
    [14]
    Use of the silver catalyst according to claim 8 or 13 for producing ethylene oxide by oxidizing ethylene.
    [15]
    A silver catalyst comprising the alpha alumina support of claim 1 or the alpha alumina support prepared by the process of any of claims 2-7.
    类似技术:
    公开号 | 公开日 | 专利标题
    NL2007510A|2012-04-02|An alumina support for silver catalyst, its preparation and its use.
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    同族专利:
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    KR101905604B1|2018-10-08|
    US20120083613A1|2012-04-05|
    CN102441435B|2014-01-01|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    CN201010501992.8A|CN102441435B|2010-09-30|2010-09-30|Method for preparing alumina carrier for silver catalyst, carrier prepared by using method and application thereof|
    CN201010501992|2010-09-30|
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