NOx Removal Catalysis

Abstract

This paper surveys the most important catalytic emission control technologies being employed or near commercialization for the removal of nitrogen oxides (NOx) from the exhausts of mobile sources under lean conditions. Urea/Ammonia-SCR systems and NOx Storage/Reduction (NSR) catalysts will be addressed, with particular attention to the specific demands related to the mobile applications. In the first part of the paper the transient kinetics of standard de-NOx SCR reaction over commercial V-W/Ti SCR catalysts and the dynamic model of the honeycomb reactor will be addressed. Then the validation of the dynamic model with integral reactor measurements and full-scale transients in vehicles will be illustrated. The second part presents a complete and quantitative understanding of the NOx storage chemistry of a Pt-Ba/Al2O3 “Lean NOx Trap” catalyst