SCR PEROVSKITE WITH AN OVERLAYER SCR COMPONENT AS AN AMMONIA OXIDATION CATALYST AND A SYSTEM FOR EXHAUST EMISSION CONTROL ON DIESEL ENGINES

摘要

An ammonia slip control catalyst having a perovskite-containing layer and a separate layer containing an SCR catalyst is described. The ammonia slip catalyst may have two stacked layers, a top over layer containing an SCR catalyst and a bottom layer containing perovskite. The ammonia slip catalyst can be alternately arranged in successive layers, the SCR catalyst being upstream in the flow of exhaust gas with respect to perovskite. A system comprising an ammonia slip catalyst upstream of a PGM-containing ammonia oxidation catalyst and a method of using the system are described. The system allows high efficiency ammonia oxidation with good nitrogen selectivity. Methods of making and using ammonia slip catalysts for reducing ammonia slip and selectively converting ammonia to N2 are described.