Process for preparation of a catalyst carrier

Abstract

This invention relates to catalyst carriers to be used as supports for metal and metal oxide catalyst components of use in a variety of chemical reactions. More specifically, the invention provides a process of formulating a low surface area alpha alumina carrier that is suitable as a support for silver and the use of such catalyst in chemical reactions, especially the epoxidation of ethylene to ethylene oxide. A precursor for a catalyst support comprises an admixture of an alpha alumina and/or a transition alumina; a binder; and either a solid blowing agent which expands, or propels a gas upon the application of sufficient heat, and optionally contains talc and/or water soluble titanium compound.

1 . A process for producing a catalyst support which comprises:
 a) preparing a precursor for a catalyst support which comprises an admixture of an alpha alumina and/or a transition alumina; a binder; a solid blowing agent which expands, or propels a gas upon the application of sufficient heat, and water; thereafter   b) molding the resultant precursor into a structure; thereafter   c) heating said structure for a sufficient time and at a sufficient temperature to cause the blowing agent to form a porous structure, and thereafter   d) heating the porous structure for a sufficient time and at a sufficient temperature to fuse the porous structure and thereby form a porous catalyst support.   
     
     
         2 . The process of  claim 1  wherein the blowing agent comprises a composition of thermoplastic shells which encapsulate a hydrocarbon, which hydrocarbon expands the thermoplastic shells upon the application of sufficient heat. 
     
     
         3 . The process of  claim 1  wherein the blowing agent comprises a granular blowing agent which propels a gas upon the application of sufficient heat. 
     
     
         4 . The process of  claim 3  wherein the solid blowing agent comprises a material selected from the group consisting of p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, and azodicarbonamide, H 2 NCO—N═N—CONH 2 , and combinations thereof. 
     
     
         5 . The process of  claim 1  wherein the alpha alumina and/or a transition alumina component comprises one or more alpha aluminas, and optionally one or more transition aluminas. 
     
     
         6 . The process of  claim 1  wherein the binder comprises a material selected from the group consisting thermally decomposable organic compounds, clays, silica, silicates of elements of Group II of the Periodic Table of the elements, and combinations thereof. 
     
     
         7 . The process of  claim 1  wherein step c), step d) or both step c) and step d) are conducted in an atmosphere of an inert gas, and optionally an oxidizing gas. 
     
     
         8 . A process for producing a catalyst which comprises:
 a) preparing a precursor for a catalyst support which comprises an admixture of an alpha alumina and/or a transition alumina; a binder; a solid blowing agent which expands, or propels a gas upon the application of sufficient heat, and water; thereafter   b) molding the resultant precursor into a structure; thereafter   c) heating said structure for a sufficient time and at a sufficient temperature to cause the blowing agent to form a porous structure, thereafter   d) heating the porous structure for a sufficient time and at a sufficient temperature to fuse the porous structure and thereby form a porous catalyst support; and then   e) depositing a catalytically effective amount of silver onto a surface of the catalyst support.   
     
     
         9 . The process of  claim 8  wherein the blowing agent comprises a composition of thermoplastic shells which encapsulate a hydrocarbon, which hydrocarbon expands the thermoplastic shells upon the application of sufficient heat. 
     
     
         10 . The process of  claim 8  wherein the blowing agent comprises a granular blowing agent which propels a gas upon the application of sufficient heat. 
     
     
         11 . The process of  claim 10  wherein the solid blowing agent comprises a material selected from the group consisting of p-toluenesulfonylhydrazide, benzenesulfonylhydrazide, and azodicarbonamide, H 2 NCO—N═N—CONH 2 , and combinations thereof. 
     
     
         12 . The process of  claim 8  wherein the alpha alumina and/or a transition alumina component comprises one or more alpha aluminas, and optionally one or more transition aluminas. 
     
     
         13 . The process of  claim 8  wherein the binder comprises a material selected from the group consisting of thermally decomposable organic compounds, clays, silica, silicates of elements of Group II of the Periodic Table of the elements, and combinations thereof. 
     
     
         14 . The process of  claim 8  wherein step c), step d) or both step c) and step d) are conducted are conducted in an atmosphere of an inert gas, and optionally an oxidizing gas. 
     
     
         15 . The process of  claim 8  further comprising depositing a promoting amount of a promoter onto the surface of the catalyst support, the promoter comprising one or more alkali metal containing compounds, one or more transition metal containing compounds, one or more sulfur components, one or more fluorine containing components, or combinations thereof. 
     
     
         16 . The catalyst produced by the process of  claim 3 . 
     
     
         17 . The catalyst produced by the process of  claim 8 . 
     
     
         18 . A process for the oxidation of ethylene to ethylene oxide which comprises the vapor phase oxidation of ethylene with molecular oxygen in a fixed bed, tubular reactor, in the presence of the catalyst produced by the process of  claim 8 . 
     
     
         19 . A process for the oxidation of ethylene to ethylene oxide which comprises the vapor phase oxidation of ethylene with molecular oxygen in a fixed bed, tubular reactor, in the presence of the catalyst produced by the process of  claim 15 .