초록 ▼

Catalysts having three types of particles dispersed on a monolith have surprising oxidation and three-way activity even after exposure to temperatures above 1000°C. The particle types are: (1) palladium dispersed on stabilized alumina; (2) ceria-containing promoter particles and (3) washcoat stabili

Catalysts having three types of particles dispersed on a monolith have surprising oxidation and three-way activity even after exposure to temperatures above 1000°C. The particle types are: (1) palladium dispersed on stabilized alumina; (2) ceria-containing promoter particles and (3) washcoat stabilization particles.

대표청구항 ▼

A catalyst effective at least for oxidation of carbon monoxide and unburned hydrocarbons in an exhaust stream, said catalyst remaining effective after exposure to a temperature greater than 1000°C., said catalyst comprising particles from each of the following three classes dispersed on a ceramic mo

A catalyst effective at least for oxidation of carbon monoxide and unburned hydrocarbons in an exhaust stream, said catalyst remaining effective after exposure to a temperature greater than 1000°C., said catalyst comprising particles from each of the following three classes dispersed on a ceramic monolithic substrate: (a) stabilized gamma alumina support particles having palladium dispersed thereon, said gamma alumina support particles being stabilized by a method selected from the group consisting of: (i) incorporation of a combination of lanthana and baria into said particles and (ii) impregnation of said particles with an aqueous dispersion of a high molecular weight polyorganosiloxane followed by heating to a temperature which is effective to decompose said polyorganosiloxane; (b) promoter particles effective for promotion of combustion of carbon monoxide, said promoter consisting essentially of an oxide selected from the group consisting of bulk ceria, bulk zirconia and mixtures thereof; and (c) washcoat stabilization particles consisting essentially of a mixed oxide selected from the group consisting of cordierite, mullite, and magnesium aluminum titanate.