DRIFT Studies on the Selectivity Promotion Mechanism of Ca-Modified Ce-Mn/TiO2 Catalysts for Low-Temperature NO Reduction with NH3

Manganese-based catalysts have shown excellent low-temperature selective catalytic reduction (SCR) activity for NOx removal. However, they would always produce a high amount of more toxic byproduct, N2O. Ca modification has been reported to be able to promote N2 selectivity for SCR catalysts, but the mechanism is still not clear. In this study, a series of Ca-modified Ce0.02Mn0.4/TiO2 SCR catalysts were utilized for mechanism study. In terms of DRIFT analysis, the addition of Ca had significantly reduced the formation of NH on catalyst surface, which limited its reaction with NO to form N2O. Furthermore, Ca addition had also caused a deceased formation of NO2, reducing its reaction with NH3 to form N2O, further increasing the N2 selectivity of the catalysts. The results present herein could be beneficial to the development of efficient low-temperature SCR catalysts, particularly for Mn-based SCR catalysts.