Preparation and Pretreatment Temperature Influence on Iron Species Distribution and N2O Decomposition in Fe–ZSM-5

Fe–ZSM-5 catalysts are prepared by FeCl3 sublimation between 320 and 850 °C. The catalysts are characterised by XRD, H2–TPR, NH3–TPD, NO adsorption by DRIFTs, and catalytic activity is evaluated for N2O decomposition. The influence of high temperature (850 °C) and pretreatment environment (air, He, He+H2O and H2) on the nature of iron species in Fe–ZSM-5 is further investigated by DRIFTs. High temperature FeCl3 sublimation results in decreased FeOx formation, easily reducible and narrow distribution of iron species in close proximity to alumina in Fe–ZSM-5. High temperature FeCl3 sublimation or pretreatment results in isolated hydroxylated iron species, –Fe(OH)2, which are not significant in Fe–ZSM-5 prepared by 320 °C FeCl3 sublimation followed by calcination below 600 °C. Fe–ZSM-5 prepared by high temperature FeCl3 sublimation show high N2O decomposition activity and the improved performance can be correlated to –Fe(OH)2 species in close proximity to alumina.