Preparation and characterization of Ce 1- xFe xO 2 complex oxides and its catalytic activity for methane selective oxidation

Abstract

A series of Ce 1- x Fe x O 2 ( x=0, 0.2, 0.4, 0.6, 0.8, 1) complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H 2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH 4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe 2O 3 to CeO 2 could promote the action between CH 4 and CeO 2. Dispersed Fe 2O 3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH 4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO 2 were also relevant to the activity. Among all the catalysts, Ce 0.6Fe 0.4O 2 exhibited the best activity, which converted 94.52% of CH 4 at 900 °C.