In-Situ NH3 Generation for SCR NOx Applications

There is currently a need for a practical solution for NOx abatement in automotive diesel engines. Technologies developed thus far suffer from inherent technical limitations. The selective catalytic reduction (SCR) of NOx under lean conditions has been proven to be successful for stationary applications.

A new approach is described to efficiently remove NOx from the exhaust of a diesel engine powered vehicle and convert it to nitrogen and oxygen. The key to the approach is the development of an on board (in-situ) ammonia generating catalyst. The ammonia is then used as a reagent to react with exhaust NO over a secondary SCR catalyst downstream. The system can remove over 85% of the exhaust NO under achievable diesel engine operating conditions, while eliminating the potential for ammonia slip with a minimal system of sensors and feedback controls.