Highly dispersed surface active species of Mn/Ce/TiW catalysts for high performance at low temperature NH3-SCR

In this work, Mn/Ce/TiW catalysts were prepared by various synthetic strategies including coprecipitation method (named as C-Mn/Ce/TiW), coprecipitation-mixing method (CM-Mn/Ce/TiW) and mixing method (M-Mn/Ce/TiW). As a result, C-Mn/Ce/TiW sample exhibited the highest NOx conversion of 90% and 99.4% at the low temperatures of 180 degrees C and 210 degrees C, respectively. This enhanced NOx conversion can be attributed to the increased surface active species served as active sites within the whole temperature range, such as Ce3+ (19.55%), Mn4+ (59.58%) and chemisorbed oxygen species (21.89%). These surface active species originated mainly from the highly dispersed CeOx and MnO2. The results revealed that the influences of the phase and texture property on catalytic activity were slight. And the gradually enhanced acidity and reducibility along with the dispersion degrees and the amount of surface active species were the main reasons for the improvement of SCR reaction. These fundamental findings will be helpful for the rational design of high-performance SCR catalysts at the low temperature.