Effect of Preparation Procedure on the Catalytic Properties of Fe-ZSM-5 as SCR Catalyst

Fe-ZSM-5 catalysts, prepared by different methods, have been characterized by BET, ICP-AES, XRD, XPS, NH3-TPD and NO-TPD and evaluated for NOx reduction according to standard NH3-SCR, NH3 oxidation and NO oxidation, in absence and presence of water. The presence of water has a significant influence on both the SCR and oxidation reactions. The most active catalyst for NH3-SCR is prepared by ion exchange using FeCl2 as iron precursor. The XPS results indicate that Fe2+ ions are the main active sites for the SCR reactions, while Fe3+ ions are the primarily active sites for oxidation of ammonia.