Enhanced CH4 and CO oxidation over Ce1-xFexO2-δ hybrid catalysts by tuning the lattice distortion and the state of surface irons species

CeO2–Fe2O3 mixed oxides are very attractive as catalysts for catalytic oxidation. Herein, we report the structural dependence of the Ce1-xFexO2-δ catalysts for CH4 combustion and CO oxidation via changing lattice distortion degrees, surface Fe2O3 states and oxygen vacancy concentrations. The lattice distortion degree and oxygen vacancy concentration of Ce-Fe-O solid solution can be tuned by changing the contents of Fe and the precipitation temperatures in the preparation process. The precipitation at relatively high temperature (70 oC) promotes the lattice distortion while lower temperature (0 oC) helps the formation of surface oxygen vacancy. The in situ DRIFT/Raman experiments and the physicochemical characterization suggest that both the CO and CH4 oxidations mainly follow a Mars-van Krevelen mechanism. Both the lattice distortion and the surface iron species play crucial role in determining the catalytic activity via affecting the redox property of the catalysts. The surface iron species, combining wi...