SELECTIVE CATALYTIC REDUCTION OF NO WITH NH3 OVER ACTIVATED CARBONS .1. EFFECT OF ORIGIN AND ACTIVATION PROCEDURE ON ACTIVITY

The activity for the selective catalytic reduction of NO with NH3 (SCR ) of a suite of different activated carbons has been studied in the te mperature range 373-550 K. The effect of origin (bituminous coal, peat , plum stones, and olive pits), activation agent (steam, CO2), and deg ree of activation was investigated by activity measurements. In genera l, the SCR activity, which is relatively high at 373 K, decreases with increasing temperature, and for some carbons increases again above 45 0 K. Two types of SCR processes are operative. In the lower temperatur e range, the narrow microporosity affects the rate by increased adsorp tion of NO, resulting in higher local concentrations. In the higher te mperature range, oxygen functional groups determine the SCR activity l evel. Precursors yielding narrow microporous carbons result in better activities below 450 K. Steam-activated carbons gave higher SCR activi ty above 450 K than CO2-activated carbons.