Ammonia Oxidation Catalysts for Mobile SCR Systems

Ammonia slip from SCR reactors can result from the incomplete conversion of NH₃ over the SCR catalyst, the release of ammonia from the catalyst surface during rapid increases in temperature and from over dosing of urea, or the ammonia precursor.

An ammonia oxidation catalyst (AMOX) offers the possibility to reduce the ammonia slip below the target amount of 10 to 20 ppm. An ammonia oxidation catalyst must be selective toward the formation of nitrogen rather than NOx or N₂O. This paper demonstrates some of the operating characteristics of an ammonia oxidation catalyst in a SCR system designed for a mobile application.