Abstract
A CuO-Al203 catalyst is well known to be active for the reduction of NO in waste gases, while it is difficult to discuss the reaction mechanism owing to change of the oxidation state of the catalyst during the course of the reaction. This work has been conducted to clarify the mechanism of NO-NH, reaction over CuO-Al203 catalysts with IR and ESR, and from kinetic studies. Experimental results confirm the following reaction mechanism: NO(g) NO"(a) NO6+ (a) +[0] NO2(a)itrato bidentate NH3(g) NH3(a) NO2(a) +NH3(a) N2-1-H20-1-[0]-1-H(a) CuO+H(a) 1/2 Cu20+1/2 H20 where (g) and (a) show a gas phase and an adsorbed state, respectively, and [0] in the controlling step probably corresponds to a lattice oxygen. NO2(a) is ascribed to a nitrato bidentate from the IR bands of a NO metal complex assigned by Blyholder et al. The catalytic activity of the catalyst falls to a stationary state level, since CuO on the carrier will be reduced to Cu2O by H(a) formed in the reaction mentioned above.
