1. Reaction mechanism for NH3-SCR of NOx over CrMn1.5O4 catalyst.
- Author
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Yuan, Zheng-nan, Guo, Rui-tang, Liu, Xiao-jing, Xu, Yi-feng, Liu, Lu, and Pan, Wei-guo
- Subjects
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ORBITAL hybridization , *ACTIVATION energy , *DENSITY functional theory , *CATALYTIC reduction , *NITROGEN oxides - Abstract
• Cr and Mn atoms are the main active sites over CrMn 1.5 O 4 (1 0 0) surface. • A reaction scheme for the reduction of NO on the surface of CrMn 1.5 O 4 catalyst is proposed. • The generation of N 2 is accomplished in two main steps. • The energy barrier for the reaction to generate NO 2 is extremely low and contributes significantly to the reduction of NO. 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. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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