Surface insights into MnOx-based catalysts containing metal oxides for the selective catalytic reduction of NOX with NH3

Abstract

The MnOx/TiO2-based NOX reduction catalyst showed moderate performance at low temperature and had the disadvantage of low N2 selectivity. Herein, the effect of Sm and Ce interactions on MnOx-based catalysts in selective catalytic reduction was investigated. Sm increased the redox properties of the MnOx catalyst and the ratio of Mn4+. Meanwhile, Ce enhanced the additional redox trait of the Sm-modified catalyst. When exposed to SO2/O2, Sm and Ce-modified MnOx not only suppressed performance degradation, but also increased N2 selectivity. Sm and Ce suppress the formation of N2O by inhibiting the formation of N2O4 intermediate species. Additionally, regardless of exposure to SO2/O2, Sm/Ce modified MnOx is an LH-ER mechanism (LangmuirHinshelwood and Eley-Rideal mechanism), but in the case of MnOx, it is suggested to be mainly an ER mechanism when exposed to SO2/O2. From these results, a strategy for improving the N2 selectivity/SCR performance of MnOx/TiO2-based catalysts with SO2 resistance was provided.