Abstract: In a process wherein diesel exhaust gas is passed through a filter to remove particulate therefrom before discharge and particulate deposited on the filter is combusted, the improvement which comprises combusting the particulate with a gas containing NO.sub.2, which may be catalytically generated in the exhaust system.

Abstract: This invention relates to catalysts, especially for the catalytic oxidation of hydrocarbons and carbon monoxide and for the catalytic reduction of oxides of nitrogen in the presence, respectively, of suitable oxidizing and reducing means.In more detail, the catalyst of the invention is capable of removing oxygen from a gas containing an excess of oxygen and restoring such removed oxygen to a gas having an oxygen deficiency, and the catalyst comprises at least one of the platinum group metals platinum, rhodium, ruthenium, palladium, indium and osmium and one or more base metals at least one of which has two or more oxidation states.