Ir-Ru bimetallic catalyst for lean NOx reduction by CO at low temperature

Abstract

The Ir-Ru catalyst has been recently developed for lean NOx reduction by CO. This bimetallic catalyst has shown an outstanding activity for CO-deNOx reaction at low temperatures in excess oxygen, which implies the possibility of replacing the commercial Urea-SCR (selective catalytic reduction) system where various problems still exist. However, since only catalytic activities under ideal conditions has been studied so far, the further research should be conducted such as reaction mechanisms and the activity test under actual conditions for real field applications. In this thesis, various studies were conducted on the Ir-Ru catalysts in CO-deNOx reaction. The Ir-Ru catalysts were evaluated under the actual feed conditions coexisting H$_2$O, C$_3$H$_6$ and SO$_2$, and optimized in terms of metal contents and ratios. We also tried to elucidate the synergistic effect and reaction pathway in the Ir-Ru system on the basis of careful investigation of multiple elementary reaction steps. In addition, the effects of the support and the promoter in the Ir-Ru catalyst were investigated to improve catalytic activity and durability.