Understanding deNOx mechanisms in transition metal exchanged zeolites

Transition-metal-containing zeolites have wide-ranging applications in several catalytic processes including the selective catalytic reduction (SCR) of NOx species. To understand how transition metal ions (TMIs) can effect NOx reduction chemistry, both structural and mechanistic aspects at the atomic level are needed. In this review, we discuss the coordination chemistry of TMIs and their mobility within the zeolite framework, the reactivity of active sites, and the mechanisms and intermediates in the NH3-SCR reaction. We emphasise the key relationship between TMI coordination and structure and mechanism and discuss approaches to enhancing catalytic activity via structural modifications.