Method for treatment of engine exhaust gases

Claim 1

In a process for reducing the amounts of hydrocarbon and carbon monoxide emitted to the atmosphere from the exhaust gases of an internal combustion engine which comprises contacting said exhaust gases with an oxidation catalyst at conditions to oxidize at least a portion of the hydrocarbon and carbon monoxide contained in said exhaust gases, the improvement comprising employing a long-lasting, durable, efficient catalyst comprising a first magnesium aluminate spinel support and, disposed as a coating on said first magnesium aluminate spinel, a mixture comprising second magnesium aluminate spinel and at least one metal component present in an amount sufficient to promote the oxidation of at least a portion of the hydrocarbon and carbon monoxide contained in said exhaust gases, said metal component comprising a metal which is less basic than is magnesium, said catalyst being formed by: 1. forming an aqueous slurry comprising magnesium aluminate spinel precursor and at least one compound of said metal, said precursor being derived from contacting in an aqueous medium a soluble inorganic magnesium salt and a soluble salt having aluminum in the anion to precipitate a first spinel precursor, the amount of water in said slurry being such as to allow said slurry to be applied to said support as a film of desired uniformity and thickness; 2. contacting said support with said aqueous slurry to form a coated support including a metal-containing film of desired uniformity and thickness on said support; and 3. treating said coated support at a temperature and for a time sufficient to calcine said magnesium aluminate spinel precursor and form said catalyst.