Fe-ZSM-5 for selective catalytic reduction of NO with NH3: a comparative study of different preparation techniques

Fe-ZSM-5 are prepared by using four different techniques: conventional aque ous ion-exchange (CA), improved aqueous ion-exchange (IA), solid-state ion- exchange (SS) and chemical vapor ion-exchange (CV). All of the catalysts sh ow very high activities for selective catalytic reduction (SCR) of NO with ammonia. However, the activities are different and follow the sequence of F e-ZSM-5 (IA) > FeZSM-5 (CA), Fe-ZSM-5 (SS) > Fe-ZSM-5 (CV). ESR results ind icate that Fe3+ ions with tetrahedral coordination are the active sites for the SCR reaction.