Effects of iron precursor and loading on the catalytic performance of FeO_x/CeO₂ catalysts for NO reduction by CO

During the catalyst synthesis process, the precursor chosen could have great impact on the physiochemical and surface properties of the catalysts. More importantly, the precursor could result in very different catalytic activities of the catalyst. In this work, two series of FeO_x/CeO₂ catalysts were prepared using iron nitrate/sulfate precursors with a wide range of Fe loading (1 wt% – 30 wt%). The catalytic activity, physical property, surface morphology and surface/molecular structure were investigated using GC, BET, XRD, Raman, FT-IR as well as SEM and EDS techniques. From the results, although the physical properties (specific surface area, total pore volume) of the catalyst were similar with different precursors, the surface composition and molecular structures were very different. The iron nitrate precursor fully transformed into FeO_x after the calcination process, whereas the iron sulfate precursor only partially transformed into FeO_x, leaving some FeSO₄ on the catalyst surface. The catalytic activity results suggested that a near monolayer coverage of FeO_x on the catalyst surface was crucial to increase the catalytic activity in the NO reduction by CO reaction, while the presence of FeSO₄ had advert impacts on the catalytic activity.