Activity of mesoporous-MnOx (m-MnOx) and CuO/m-MnOx for catalytic reduction of NO with CO

The direct reduction of NO over mesoporous manganese oxide (m-MnOx) and in the presence of CO was studied at reaction temperatures in the range from 150 to 460 °C. The conversion of NO without the reducing agent CO was limited to less than 10%, but when CO was added to the reactor feed up to 70% of the NO was reduced at a reaction temperature of 340 °C. However, the m-MnOx catalyst activity deteriorated at temperature above 340 °C due to a transformation of MnO2 to the less active Mn2O3 and Mn3O4 phases. The activity of the m-MnOx catalyst at high temperatures was enhanced by the addition of CuO. Two methods to load CuO on the m-MnOx were investigated: wet impregnation and co-precipitation. Both methods produced catalysts that achieved close to 97% NO conversion in CO at a reaction temperature of 430 °C.