Effect of ceria doping on catalytic activity and SO2 resistance of MnOx /TiO2 catalysts for selective catalytic reduction of NO with NH3 at low temperature

Abstract

ABSTRACT With its industrial applicability and low energy consumption, a process for implementing the NH3-SCR of NO at low temperatures is urgently needed. In this study, MnOx-CeO2/TiO2 (MnCe/Ti) catalysts doped with different amounts of Ce were prepared and experimentally examined for their NH3-SCR activity between 100°C and 400°C. Adding a small amount of Ce (at the Ce/Ti mole ratio of 0.05) elevated the exposure of Mn atoms on the catalyst surface, resulting in the highest NH3-SCR activity occurring between 100°C and 200°C (with a conversion rate of above 98% for the NO at 175°C). Further increasing the Ce content, however, diminished the catalytic performance. Moreover, the NH3-SCR of NO during oxidization or reduction atmosphere confirmed that oxygen species bound to the exposed Mn atoms were released more easily and the resulting vacancies were more likely to be replenished by O2 at low temperatures. In addition, incorporating Ce enhanced the SO2 resistance of the MnCe/Ti, mainly by inhibiting the accumulation of ammonium sulfates and the preferential sulfation of the Ce dopants.