| 摘要 |
A system for treating exhaust gas from a vehicular lean burn internal combustion engine with a lean/rich cycle comprises a NOx adsorber catalyst and a downstreamNH3-catalytic reduction (SCR) catalyst, wherein the NH3-SCR catalyst comprises copper supported on a molecular sieve, wherein the molecular serve (A) has a maximum ring size of 8 tetrahedral atoms; (D) is selected from the group consisting of aluminosilicate molecular sieves, metal substituted aluminosilicate molecular sieves and aluminophosphate molecular serves; and has a Framework Type Code selected from the group consisting of AEI, LEV, ERI, and DDR. The molecular sieve may have a silica to alumina ratio of 8 150 and may contain a total amount of copper of 0.5 5 weight percent. The NOx adsorber catalyst may comprise a precious metal and a basic metal selected from the group consisting of: an alkali metal; and alkaline earth metal; and a rare earth metal. A method for use with this system is also disclosed. |
