Low temperature selective catalytic reduction of NOx with NH3 over amorphous MnOx catalysts prepared by three methods

Unsupported manganese oxide catalysts with amorphous phase were prepared by three methods, and their activities for SCR of NOx with ammonia were investigated in the presence of O2. The results showed the catalysts have superior low temperature activity, and the NOx conversion is about 98% at 80 °C, and nearly 100% NOx conversion between 100 and 150 °C. Due to competing adsorption with the reactant, H2O has slight impact on the activity. The activity was suppressed with coexisting of SO2, however the deactivation of SO2 is reversible. The excellent low temperature catalytic activity of amorphous MnOx catalysts is mainly due to their amorphous phase and high specific areas.