Patent ID: 6129898
Filing Date: 2000-10-10
Classification: B01D,B01J,Y02T

Abstract:
A method for treating exhaust gases from an internal combustion engine using a nitrogen oxide trap, said method comprising the steps of:locating in the exhaust gas passage of said internal combustion engine a nitrogen oxide trap material comprising:(a) a tri-metal oxide of aluminum oxide, manganese oxide, and zirconium oxide made by sol-gel techniques; and(b) at least 0.1 wt. % platinum deposited on said oxide or incorporated therein during sol-gel technique processing, the wt. % of platinum being based on the weight of said oxide;exposing said nitrogen oxide trap to oxidizing engine exhaust gases having a lean of stoichiometric air/fuel ratio to absorb nitrogen oxides from said exhaust gas;purging said absorbed nitrogen oxides from said trap by subjecting said nitrogen oxide trap to engine exhaust gases whose air/fuel ratio is stoichiometric or rich of stoichiometry.