“…During the past few decades, much effort has been focused on the development of active catalysts for the removal of NO. Various types of catalysts, including noble metals, transition metal oxides, and mixed metal oxides, show high activity when used for the reduction of NO with NH3 (Meier and Gut, 1978;Nam et al, 1986a;Wong and Nobe, 1986). Recently, copper ionexchanged Y zeolite and H-mordenite have also been reported to be efficient catalysts for this reaction (Williamson and Lunsford, 1976; Mizumoto et al, 1979;Kiovsky et al, 1980; Nam et al, 1988; Medros et al, 1989).…”