Preparation of nanosheet Fe-ZSM-5 catalysts, and effect of Fe content on acidity, water, and sulfur resistance in the selective catalytic reduction of NO x by ammonia

Direct synthesis of nanosheet Fe-ZSM-5 catalysts and their use for selective catalytic reduction (SCR) of NO x by ammonia were studied. XRD, BET, SEM, EPR, and NH 3 -TPD were used to understand the properties of catalysts with different iron loading. XRD confirmed the presence of the ZSM-5 crystal phase, and there was no Fe 2 O 3 phase on the surface of the crystals. SEM showed the Fe-ZSM-5 catalysts comprised microspheres made up of nanosheets. EPR indicated that the iron was present as isolated Fe 3+ and FeO x oligomers uniformly dispersed throughout the crystals. NH 3 -TPD indicated that Fe-ZSM-5 (20,1:1) had maximum acid sites and density at approximately 250 and 450 °C, respectively. Fe-ZSM-5 (20,1:1) had the highest activity in the SCR reaction with NH 3 . It was also confirmed that Fe-ZSM-5 (20,1:1) had excellent resistance to SO 2 and H 2 O under the SCR reaction conditions. The effects of water vapor and SO 2 , iron loading, and the Si/(Fe + Al) ratio were also investigated for these catalysts.