Characterization and NH3-SCR reactivity of Cu-Fe-ZSM-5 catalysts prepared by solid state ion exchange: The metal exchange order effect

The selective catalytic reduction (SCR) of NO with NH3 in the presence of O2 and H2O over a series of Fe and/or Cu-containing ZSM-5 catalysts prepared by solid state ion exchange (SSIE) was investigated. A wide number of experimental techniques (ICP-AES, XRD, HRTEM, 27Al MAS NMR, NH3-TPD, DRS UV-vis, H2-TPR and EPR) have been applied to understand the metal exchange order effect on the composition, texture, structure, acidity and speciation of bimetallic materials. DRS UV-vis, H2-TPR, EPR and HRTEM experiments conducted on Cu-Fe-ZSM-5 and Fe-Cu-ZSM-5 allowed the identification of both isolated and clustered metal species differing in their amount, environment and degree of aggregation leading to a different catalytic behaviour of both catalysts.