US Patent 8057767 Base metal oxides oxidation catalyst

Chemical species such as nitrogen oxide (NO), carbon monoxide, and low molecular weight hydrocarbons (e.g., C1-C5 and saturated or ethylenically unsaturated) in an oxygen-containing gas stream, such as the exhaust stream from a diesel engine, or other lean burn engine, may be oxidized using a mixture of MnOx with one or more other base metal oxides, with or without palladium. The oxidation is effective at temperatures above about 200° C. to convert about ninety percent or more of the carbon monoxide to carbon dioxide and to consume the hydrocarbons. The oxidation is also effective to convert much of the NO to NO2. In general, the mixed base metal oxides may be used as catalysts for the oxidation of nitrogen oxide in hot gas streams containing oxygen. They may optionally be used in a combination with palladium or platinum. But platinum, which is very expensive, does not have to be used in such oxidation reactions.