REDUCTION OF SULFUR-DIOXIDE BY CARBON-MONOXIDE TO ELEMENTAL SULFUR OVER COMPOSITE OXIDE CATALYSTS

The catalyst activity of fluorite-type oxide, such as ceria and zircon ia, for the reduction of sulfur dioxide by carbon monoxide to elementa l sulfur can be significantly promoted by active transition metals, su ch as copper. More than 95% elemental sulfur yield, corresponding to a lmost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst with a feed gas of stoichiometric composition ([CO]/[SO 2] = 2) at temperatures above 450-degrees-C. This type of mixed metal oxide catalyst has stable activity and is resistant to water and carbo n dioxide poisoning. XPS analysis found copper in the Cu-Ce-O oxide in a reduced oxidation state (Cu1+, Cu0). The stable fluorite-type struc ture, regarded as the backbone structure of the catalyst, existed in b oth the fresh and the spent catalyst. The high activity resulted from the strong interaction of transition metal and fluorite oxide.