Methane catalytic combustion over CeO2-ZrO2-Sc2O3 mixed oxides

Abstract

In this work nanostructured CeO2-ZrO2-Sc2O3 mixed oxides prepared by citrate complexation method are studied. The effects of the co-substitution of ZrO2 and Sc2O3 in the CeO2 lattice are assessed in terms of the reducibility of the samples and their catalytic activity towards oxidation of methane. In situ X-ray absorption near edge structure (XANES) and X-ray powder diffraction (XPD) experiments with synchrotron light were performed to study the oxygen exchange capacity of these ternary oxides in reaction conditions and their structure stability. Catalytic experiments for complete methane combustion indicated a superior performance of samples containing Sc2O3 compared to the CeO2-ZrO2 one in terms of reaction onset temperature, conversion values and activation energy. Samples with 4 at% and 6 at% Sc doping exhibited a stable behavior at 800 °C during 7.5 h on-stream experiments. Structural stability was confirmed by in-situ XPD experiments with no secondary phase segregation or carbon deposition in reaction conditions.