SMALL PORE MOLECULAR SIEVE SUPPORTED COPPER CATALYSTS DURABLE AGAINST LEAN/RICH AGING FOR REDUCTION OF NITROGEN OXIDES

摘要

To provide a method of using a catalyst in treating exhaust gas from a vehicular internal combustion engine with a lean/rich cycle, such as a diesel engine or a gasoline engine, or an engine powered by liquid petroleum gas (LPG) or natural gas.SOLUTION: A method of using a catalyst comprises exposing a catalyst to at least one reactant in a chemical process. The catalyst comprises copper and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms. The chemical process undergoes at least one period of exposure to a reducing atmosphere. The catalyst has an initial activity and the catalyst has a final activity after the at least one period of exposure to the reducing atmosphere. The final activity is within 30% of the initial activity at a temperature between 200°C and 500°C.SELECTED DRAWING: Figure 3