초록 ▼

A catalyst has a base catalyst layer containing platinum and barium as precious metal supported by alumina and an over catalyst layer containing platinum and rhodium as precious metal supported by zeolitr. The platinum and rhodium in the over catalyst layer activate NOx and HC so as to make them mor

A catalyst has a base catalyst layer containing platinum and barium as precious metal supported by alumina and an over catalyst layer containing platinum and rhodium as precious metal supported by zeolitr. The platinum and rhodium in the over catalyst layer activate NOx and HC so as to make them more reactive in terms of energy, and the barium in the base catalyst layer makes the platinum be more dispersive in the base catalyst layer. Under the existence of dispersive platinum, NOx in exhaust gas is decomposed and purified by reaction with reactive NO.sub.2 and partially oxidized HC generated in the over catalyst layer.

대표청구항 ▼

[ What is claimed is:] [1.] A catalyst for purifying exhaust gas from a lean-burn engine with two catalyst coating layers on a carrier by reacting NOx in the exhaust gas with HC in an excessive oxygen atmosphere, comprising:a base catalyst coating layer directly disposed on a carrier, said base cata

[ What is claimed is:] [1.] A catalyst for purifying exhaust gas from a lean-burn engine with two catalyst coating layers on a carrier by reacting NOx in the exhaust gas with HC in an excessive oxygen atmosphere, comprising:a base catalyst coating layer directly disposed on a carrier, said base catalyst coating layer containing at least platinum (Pt) and at least one alkaline earth metal or alkaline metal; andan over catalyst coating layer disposed over said base catalyst coating layer, said over catalyst coating layer containing zeolite and a noble metal.