Method for making a highly selective ethylene oxide catalyst

Abstract

A process for the preparation of a catalyst useful for the vapor phase production of ethylene oxide from ethylene and oxygen comprising providing a catalyst precursor comprising an inert support having a catalytically effective amount of a silver containing compound, a promoting amount of an alkali metal containing compound, and a promoting amount of a transition metal containing compound disposed thereon; calcining the catalyst precursor to convert the silver in the silver containing compound to metallic silver by heating the catalyst precursor to form a catalyst; and curing the catalyst in an inert gas atmosphere at temperatures of about 250° C. to about 600° C. for a period of about 1 hour to 200 hours.

What we claim is: 
     
         1 . A process for the preparation of a catalyst useful for the vapor phase production of ethylene oxide from ethylene and oxygen comprising:
 providing a catalyst precursor comprising an inert support having a catalytically effective amount of a silver containing compound, a promoting amount of an alkali metal containing compound, and a promoting amount of a transition metal containing compound disposed thereon;   calcining the catalyst precursor to convert the silver in the silver containing compound to catalytically active metallic silver and to remove substantially all volatile components by heating the catalyst precursor to form a catalyst containing the catalytically active metallic silver and substantially no volatile components; and   curing the catalyst produced from the calcining in an inert gas atmosphere at a temperature of about 250° C. to about 600° C. for a period of about 1 hour to 200 hours.   
     
     
         2 . The process of  claim 1 , wherein the calcining is performed in the presence of an inert gas atmosphere. 
     
     
         3 . The process of  claim 2 , wherein the calcining is performed at a temperature from about 300° C. to about 500° C. 
     
     
         4 . The process of  claim 1 , wherein the calcining is performed in the presence of an oxygen-containing atmosphere. 
     
     
         5 . The process of  claim 4 , wherein said oxygen-containing atmosphere is air comprising from 0.1 to 21% oxygen. 
     
     
         6 . The process of  claim 4 , wherein the calcining is performed at a temperature less than about 300° C. 
     
     
         7 . The process of  claim 1 , wherein the temperature of the curing is from about 300° C. to about 450° C. 
     
     
         8 . The process of  claim 1 , wherein the period of the curing is about 2 hours to 6 hours. 
     
     
         9 . The process of  claim 1 , further comprising a step of cooling the catalyst to less than about 50° C. before the curing. 
     
     
         10 . The process of  claim 4 , further comprising a step of cooling the catalyst to less than about 50° C. before the curing. 
     
     
         11 . The process of  claim 1 , wherein the transition metal comprises rhenium. 
     
     
         12 . The process of  claim 1 , wherein the alkali metal containing compound comprises cesium. 
     
     
         13 . The process of  claim 1 , wherein the calcining is performed on a moving belt calciner with multiple heating zones and the curing is performed in one of the heating zones of said moving belt calciner. 
     
     
         14 . The process of  claim 1 , wherein the calcining is performed on a moving belt calciner with multiple heating zones, and after cooling, the curing is performed in an ethylene oxide reactor.