1 monoxide Titanates

Reduction of sulfur dioxide by methane is the basis of an Allied process for converting by-product sulfur dioxide to sulfur (232). The reaction is carried out in the gas phase over a catalyst. Reduction of sulfur dioxide to sulfur by carbon in the form of coal has been developed as the Resox process (233). The reduction, which is conducted at 550—800°C, appears to be promoted by the simultaneous reaction of the coal with steam. The reduction of sulfur dioxide by carbon monoxide tends to give carbonyl sulfide [463-58-1] rather than sulfur over cobalt molybdate, but special catalysts, eg, lanthanum titanate, have the abiUty to direct the reaction toward producing sulfur (234). 

Reduction with carbon monoxide at high temperatures can form either carbonyl sulfide or sulfur depending on the catalyst used. With cobalt molybdate, COS is the primary product. On the other hand, lanthanum titanate catalyzes the reaction to form sulfur. 

PMMA PNGV PO POx PPMA PrOx PTFE PVD PZT Poly-methylmethacrylate Partnership of New Generation Vehicles Propylene oxide Partial oxidation Poly-methyl methacrylate Preferential carbon monoxide oxidation Poly-tetrafluorethylene Physical vapor deposition Lead-zirconate-titanate... 

Rare earth containing catalysts are useful in stationary pollution control devices as for example lanthanum titanate catalysis in the reduction of sulphur dioxide with carbon monoxide to yield carbon dioxide and elemental sulphur. The disposal of elemental sulphur is far less hazardous than that of effluent from an SO2 scrubber. 

Lutz B. L., Debergh C., and Owen T. (1983a) Carbon-monoxide in the atmosphere of Titan—search and discovery. Publ. Astron. Soc. Pacific 95, 593—593. 

Naisbitt, S. C., Pratt,K. F. E., WiUiams, D. E. and Parkin, I. P. (2006) A microstmctural model of semiconducting gas sensor response The effects of sintering temperature on the response of chromium titanate (CTO) to carbon monoxide. Sensors and Actuators B-Chemical 114,969-77. 

Examples The roasting of ores, the chemical adsorption of hydrogen sulfide by metal oxides (forming sulfides), the conversion of a metal oxide with a volatile non-metal oxide into a salt (e.g., the chemical adsorption of sulfur dioxide and oxygen by calcium oxide), the reductive chlorination of ilmenite (iron titanate) whereby iron chloride and titanium oxide are formed. In some processes a second solid reactant is present (e.g., carbon) that also reacts with the gaseous reactant, forming another gaseous reactant (e.g., carbon monoxide). 

Marten, A., Gautier, D., Tanguy, L., Lecacheux, A., Rosolen, C., Paubert, G. (1988). Abundance of carbon monoxide in the stratosphere of Titan from millimeter heterodyne observations. Icarus, 76, 558-62. 

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