| abstract |
SUMMARY OF THE INVENTION A catalytic trap (10) for treating exhaust gas generated by a lean burn engine or a partially lean burn engine is resistant to deactivation due to aging under lean operating conditions at elevated temperatures. . The catalyst trap (10 or 10 ') of the carrier member (12 or 12/12' includes a), NO x absorbent thereon, and at least 25 g / cubic foot up to about 300 g / ft of Pd amount of palladium A catalyst trap material (20) containing a hard-to-melt metal oxide carrier in which a catalyst component is dispersed is coated in layers (20a, 20b) separated as needed. Platinum and / or rhodium catalyst components may also be present. The NO x absorbent can be a basic oxygenated compound of one or more alkali and / or alkaline earth metals, for example, cesium and / or barium. Preparation includes a method of coating the the NO x absorbent by post immersion method. Uses include alternating lean and stoichiometric or rich periods of operation and optionally oxidizing hydrocarbons in the exhaust gas prior to contacting the exhaust gas with the catalyst trap (10). It is. |