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 NH3-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 Fe2O3 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. NH3-TPD indicated that Fe-ZSM-5 (20,1:1) had maximum acid sites and density at approximately 250 and 450 A degrees C, respectively. Fe-ZSM-5 (20,1:1) had the highest activity in the SCR reaction with NH3. It was also confirmed that Fe-ZSM-5 (20,1:1) had excellent resistance to SO2 and H2O under the SCR reaction conditions. The effects of water vapor and SO2, iron loading, and the Si/(Fe + Al) ratio were also investigated for these catalysts.