2-way and 3-way catalyst compositions comprising tin (IV) oxide (SnO2) and chromium (VI) oxide (CrO3) for use in catalytic converters for vehicle exhaust gas systems, such catalyst compositions being effective in the catalytic oxydation of carbon monoxide and unburnt hydrocarbons, and in the catalytic reduction of nitrogen oxides contained in the vehicle exhaust.

Vehicle exhaust gas systems

A method for the catalytic oxidation of carbon monoxide and unburnt hydrocarbon components of vehicle exhaust gas streams is disclosed. The method comprises using as the catalyst a mixed oxide catalyst composition consisting essentially of tin (IV) oxide (SnO 2 ), chromium (VI) oxide (CrO 3 ) and copper (II) oxide (CuO) free from platinum and other noble metals or noble metal oxides, and containing an Sn:Cr weight ratio (calculated as SnO 2 :CrO 3 ) in the range 99:1 to 1:99, and copper (II) oxide (CuO) in an amount of from 0.5 to 100% by weight, based on the combined weight of SnO 2 and CrO 3 . The catalyst composition having been prepared by impregnating tin(IV) oxide (SnO 2 ) with chromium(VI) oxide (CrO 3 ) and copper oxide (CuO) and calcining the resulting product.

M.J. Fuller

Papers

Catalytic reduction of nitric oxide by carbon monoxide over SnO/sub 2/--CuO gels