Catalysts useful in the purification of silicon tetrafluoride

Abstract

Processes for purifying silicon tetrafluoride source gas by subjecting the source gas to one or more purification processes including: contacting the silicon tetrafluoride source gas with an ion exchange resin to remove acidic contaminants, contacting the silicon tetrafluoride source gas with a catalyst to remove carbon monoxide, by removal of carbon dioxide by use of an absorption liquid, and by removal of inert compounds by cryogenic distillation; catalysts suitable for removal of carbon monoxide from silicon tetrafluoride source gas and processes for producing such catalysts.

1 . A catalyst for removing impurities from a silicon tetrafluoride gas, the catalyst comprising:
 an inert substrate selected from the group consisting of zirconia, alumina silicate, silica, alumina, yttria and mixtures thereof, and   a catalytic metal oxide comprising a catalytic metal selected from the group consisting of copper, manganese, chromium, cobalt, thallium, molybdenum, silver and mixtures thereof at or near the surface of the inert substrate.   
     
     
         2 . A catalyst as set forth in  claim 1  wherein the catalytic metal oxide comprises a catalytic metal selected from the group consisting of copper, manganese and mixtures thereof. 
     
     
         3 . A catalyst as set forth in  claim 1  wherein the inert substrate comprises zirconia, alumina silicate and mixtures thereof. 
     
     
         4 . A catalyst as set forth in  claim 1  wherein the inert substrate comprises a stabilizer comprising a metal selected from the group consisting of lanthanides, actinides, magnesium, yttrium, calcium, and mixtures thereof. 
     
     
         5 . A catalyst as set forth in  claim 4  wherein the inert substrate comprises less than about 0.1% by weight stabilizer. 
     
     
         6 . A catalyst as set forth in  claim 1  wherein the inert substrate comprises less than about 0.1% by weight yttrium oxide as a stabilizer. 
     
     
         7 . A catalyst as set forth in  claim 1  wherein the catalyst comprises at least about 95% inert substrate by weight, less than about 3% catalytic metal by weight and less than about 0.5% stabilizer by weight. 
     
     
         8 . A catalyst as set forth in  claim 1  wherein the catalyst comprises from about 0.001% to about 1.0% by weight catalytic metal. 
     
     
         9 . A catalyst as set forth in  claim 1  wherein the catalyst comprises from about 95% to about 99.999% by weight inert substrate. 
     
     
         10 . A catalyst as set forth in  claim 1  wherein the substrate has a surface area from about 1 m 2 /g to about 1000 m 2 /g. 
     
     
         11 . A catalyst as set forth in  claim 1  wherein the substrate has a bulk porosity f from about 30% to about 80%. 
     
     
         12 . A catalyst as set forth in  claim 1  wherein the substrate has a micro-porosity of from about 1% to about 20%.