Method for producing a supported catalyst

A method for producing a supported metal-containing catalyst comprising a first magnesium alumina spinel support, and disposed as a coating on said first magnesium aluminate spinel support, a mixture comprising second magnesium aluminate spinel and at least one catalytically active metal component sufficient to promote at least one of the following:

• (a) the oxidation of at least a portion of the hydrocarbon and carbon monoxide contained in the exhaust gases of an internal combustion engine and (b) the chemical reduction of at least a portion of the nitrogen oxides contained in the exhaust gases of an internal combustion engine, said metal being less basic than magnesium, which comprises:
• 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 thickness and uniformity on said support;
• and
• 3. treating said coated support at a temperature and for a time sufficient to calcine said material and form said supported metal-containing catalyst.