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

The MnOx/TiO 2 -based NO X reduction catalyst showed moderate performance at low temperature and had the disadvantage of low N 2 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 Mn 4+ . Meanwhile, Ce enhanced the additional redox trait of the Sm-modified catalyst. When exposed to SO 2 /O 2 , Sm and Ce-modified MnOx not only suppressed performance degradation, but also increased N 2 selectivity. Sm and Ce suppress the formation of N 2 O by inhibiting the formation of N 2 O 4 intermediate species. Additionally, regardless of exposure to SO 2 /O 2 , Sm/Ce modified MnOx is an LH-ER mechanism (Langmuir-Hinshelwood and Eley-Rideal mechanism), but in the case of MnOx, it is suggested to be mainly an ER mechanism when exposed to SO 2 /O 2 . From these results, a strategy for improving the N 2 selectivity/SCR performance of MnOx/TiO 2 -based catalysts with SO 2 resistance was provided. • Sm and Ce improved the NO X reduction and SO 2 resistance of MnO X /TiO 2 . • Redox cyclability had an effect on performance improvement. • Inhibition of N 2 O 4 intermediate species significantly increased N 2 selectivity.