Promotion Effect of Iron on Activity and N2 Selectivity of Mn/Ce Catalysts in the NH3-SCR Reaction

Manganese oxides are known to have good low-temperatureSCR performance,whereas improving their medium- and high-temperature catalytic performanceand N-2 selectivity remain a challenge. Herein, manganese-basedternary catalysts Fe-Mn/Ce, using CeO2 as the carrierand Fe as the second active component, were constructed to effectivelysolve this problem. Fe-Mn/Ce catalysts show excellent catalyticperformance, with NO x conversions of morethan 90% over a wide operating temperature range (164.5-419.4 degrees C) with high and N-2 selectivity. Further investigationshowed that, for the Fe-Mn/Ce catalyst with rich redox sitesand surface acidity, higher amounts of Fe2+ and Mn4+ are the important factors promoting excellent SCR reactivity.Besides, the Fe modification can generate effective electron transferto reduce the N2O generation pathway and increase the catalyticreaction sites, thus enhancing the overall catalytic performance.

Automated summary

In this study, the challenges of low selectivity and inadequate catalytic performance of manganese oxides in medium and high-temperature SCR reactions were effectively addressed by using manganese-based ternary catalysts Fe-Mn/Ce. The Fe-Mn/Ce catalysts exhibited excellent catalytic performance, with NO x conversions exceeding 90% over a wide operating temperature range (164.5-419.4 degrees C) and high N-2 selectivity. Further research revealed that higher proportions of Fe2+ and Mn4+ in the Fe-Mn/Ce catalysts with abundant redox sites and surface acidity were important factors for promoting excellent SCR reactivity. Additionally, the modification with Fe facilitated effective electron transfer, reducing the pathway of N2O generation and increasing catalytic reaction sites, thereby enhancing overall catalytic performance.