HYBRID EXHAUST GAS CATALYST

摘要

This invention is directed to a hybrid catalyst for the purification of engine exhaust gas generated by an engine which is operated under both stoichiometric and leanburn (oxygen rich) air/fuel combustion ratios. The hybrid catalyst comprises a first catalyst consisting of a catalytic material capable of reducing nitrogen oxides under lean-burn engine operating conditions and a second catalyst consisting of a three-way catalyst. Preferably, the hybrid catalyst is a layered combination of the catalysts where the first catalyst is layered on the second catalyst which is carried on a substrate like cordierite.