Perovskite with a topcoat SCR component as an ammonia oxidation catalyst and exhaust gas cleaning system for diesel engines

It contains an ammonia slip catalyst having a layer perovskite, and described in a separate layer that contains an FTIR catalyst. The ammonia slip catalyst may have two stacked layers, wherein the top coating comprises an SCR catalyst and the lower layer contains a perovskite. The ammonia slip catalyst may alternatively be arranged to in sequential layers, wherein the SCR catalyst is located in the exhaust gas stream relative to the perovskite upstream. a system that includes the ammonia slip catalyst upstream of a PGM-containing ammonia oxidation catalyst, and methods for using the system are described. The system allows a high ammonia oxidation with good nitrogen selectivity. There are methods of making and using the ammonia slip catalyst for the reduction of ammonia slip and selective conversion of ammonia to N