Reaction mechanism for NH 3-SCR of NO x over CrMn 1.5 O 4 catalyst

A comprehensive study of the catalytic behavior of CrMn 1.5 O 4 catalysts in the selective catalytic reduction (SCR) of nitrogen oxides (NO x ) using NH 3 as the reductant was presented. The active sites for NO x reduction and NH 3 adsorption on the CrMn 1.5 O 4 surface were identified by density functional theory (DFT) calculations. The study elucidates the mechanism of NH 3 dehydrogenation and NO reduction, revealing key intermediates and reaction pathways. DFT calculation results showed that the chromium and manganese atoms on the surface, participating in the specifically d- sp hybridization with NH 3 , NO, played a key role in adsorption, and that NH 3 dehydrogenation led to the formation of NH 2 , which was a key intermediate in the selective catalytic reduction reaction. To further understand the process of NO generation to NO 2 and N 2 O on the surface of CrMn 1.5 O 4 catalyst, the chain reaction steps of NO reduction were proposed. Among them, NO was oxidized to NO 2 , and the very low reaction energy barrier contributed greatly to the fast SCR reaction, while the generation of the unwanted product N 2 O had a relatively high energy barrier, so the reaction was not easy to occur. These findings contribute to a deeper understanding of the intricate catalytic behavior of CrMn 1.5 O 4 catalysts, which will aid in the development of better SCR catalysts for the effective removal of NO x in industrial settings.