Progress of performance optimization for Mn-based SCR catalysts at low-temperature

The emission control of nitrogen oxides (NOx) is the focus and difficulty of air pollution control in China. Selective catalytic reduction (SCR) technology is mainly used in NOx emission control. The development of efficient and stable catalysts for SCR at low-temperature can avoid the high energy consumption of flue gas reheating, which has significant energy saving and carbon reduction benefits. Manganese oxides (MnOx) exhibit excellent redox properties due to variable chemical states and abundant lattice defects, and have very strong surface acidity, showing good low-temperature activity in the reaction of catalytic reduction of NOx. However, the Mn-based catalysts show low N2 selectivity and poor resistance to H2O/SO2, making it difficult to achieve efficient and stable deNOx over a long period of time. In recent years, the modification and enhancement of Mn-based catalysts has been researched extensively, which accelerates the pace of industrial application of Mn-based catalysts. From the aspects of low-temperature activity, N2 selectivity and stability, this review summarized the latest research progress on reaction mechanism, elemental doping and structure design of Mn-based catalysts, pointing out the current research focuses and difficulties, which can provide references for the next research.