Surface science studies of selective catalytic reduction of NO: Progress in the last ten years

Selective catalytic reduction (SCR) of NOx is one of the important strategies in regulating NOx emissions. In the past several decades, the reactions of NOx (mainly NO) with H2, CO, NH3 and hydrocarbons have been extensively investigated under ambient conditions and have been summarized in numerous reviews. Nonetheless, many questions appear to be difficult to answer under ambient conditions, e.g., the pathways through which the reactions proceed. The introduction and development of modern surface science technology has played an indispensable role and is widely employed in the studies of the SCR of NOx, greatly helping to elucidate the mechanisms of the reactions with CO, H2, and NH3. However, so far, there are few review papers systematically summarizing the progress of such studies. ly, systematic surface science studies have been conducted on the mechanisms of SCR of NO with organic molecules including ethylene, benzene, and ethanol, which are much more complicated than those with H2, CO and NH3 and have drawn much less attention before. It is confirmed that these reactions can be reliably and most importantly, reproducibly probed by surface science technology, but a great deal of work remains to be done. Delmon et al. have provided a very thorough review of the researches on catalytic removal of NO (reactions with H2, CO and NH3) up to 1998, in which the reactions conducted both under ambient and UHV conditions were included, this review mainly concentrates on the progress made since 1998.