Low-temperature NOx removal for flue gas cleanup

NO x reduction with hydrocarbons is studied at temperatures around 150 °C to develop an easy retrofit NO x removal process to be located downstream of the particulate control device for flue gas cleanup. Acetone is the most active hydrocarbon reductant for NO reduction in the presence of O2 and H2O. At 150 °C, 35% NO reduction was obtained over 5% Cu-2% Ag/PCB. The activity, however, is greatly decreased by the presence of SO 2 . NO oxidation to NO 2 is studied for further improving the NO reduction activity because NO 2 is known to be more reactive than NO. Active carbon fibers and PCB active carbon are both active for NO oxidation at low temperature, but the activity decreased with temperature. Ten percent Co 3 O 4 /Al 2 O 3 and 5% Au/Co 3 O 4 are not active for NO oxidation in the absence of SO 2 and at 150 °C, but are very active in the presence of SO 2 and H2O. Five percent Au/Co 3 O 4 is especially stable for NO oxidation to N0 2 at temperatures from 120 to 150 °C for more than 15 h.