A Mössbauer and structural investigation of Fe-ZSM-5 catalysts: Influence of Fe oxide nanoparticles size on the catalytic behaviour for the NO-SCR by C3H8

▶ In over-exchanged Fe-ZSM-5 catalysts at high Fe loading no bulk Fe oxides but nanosized FexOy species, undergoing a superparamagnetic behaviour, are formed. ▶ In the two Fe-ZSM-5 catalysts the Fe oxide nanoparticles are varying in size and the relative abundance of larger/smaller nanoparticles is different ▶ Larger FexOy nanoparticles appear to be prevailing in the catalyst at higher Fe loading. ▶ The larger FexOy nanoparticles are characterized by a very low activity for the NO-SCR reaction. ▶ The larger FexOy nanoparticles enhance the hydrocarbon total combustion to CO2, thus limiting the formation of the undesired CO along the NO-SCR reaction.