Abstract: A catalyst system and method of making the same is taught for treating exhaust gases from an internal combustion engine. A catalyst system includes a substrate and a washcoat on the substrate. The washcoat is formed of zirconia. A catalyst is placed on the washcoat consisting of rhodium metal or rhodium metal with another catalyst metal. By using zirconia as a washcoat, the rhodium is not dissolved into the washcoat during periods when the catalyst system is subjected to high temperature oxidizing conditions, as is the case when a gamma alumina washcoat is used.

Abstract: A catalyst system is taught for treating exhaust gases from an internal combustion engine. The catalyst system includes a substrate and a wash coat on the substrate. The wash coat is formed substantially of alpha phase alumina. A catalyst is placed on the wash coat consisting of rhodium metal or rhodium metal with another catalyst metal. By using alpha phase alumina as the wash coat, the rhodium is not dissolved into the wash coat during periods when the catalyst system is subjected to high temperature oxidizing conditions.

Abstract: This disclosure teaches a stabilized rhenium catalyst in which the rhenium does not volatilize away from a catalyst substrate when oxidized to its higher valence state. The rhenium is protected by having sufficient refractory oxide available on the catalyst substrate to trap any higher oxide of rhenium developed when the rhenium is oxidized.