Effects of preparation methods on CoAlOx/CeO2 catalysts for methane catalytic combustion

The novel supported CoAlOx/CeO2 catalysts have been synthesized via four preparation processes [impregnation (IWI), microwave in-situ grown (MW), impregnation-combustion (CS) and plasma treatment (P)], and investigated for methane catalytic combustion. The results indicated that preparation method played a vital role in controlling structural properties of the catalysts, resulting in a significant difference in catalytic performance. The activities of synthesized catalysts increased and optimised in the following order: CoAlOx/CeO2-IWI < CoAlOx/CeO2-MW < CoAlOx/CeO2-CS < CoAlOx/CeO2-P. The CoAlOx/CeO2-P catalyst possessed the lower apparent activation energy (Ea was 92.2 +/- 0.1 kJ/mol) and a better performance with a lower reaction temperature at 415 C for the 50% methane conversion, while the conversion was only 5% for the CoAlOx/CeO2-IWI sample at this temperature, as comparison. The samples were characterized by X-ray photoelectron Spectroscopy (XPS) and several other techniques. The CoAlOx/CeO2-P catalyst possessed a higher ratio of surface absorbed oxygen and lattice oxygen (O-ads/O-latt) which enabled the enhancement of its catalytic activity. The plasma method provided an effective path to develop the efficient combustion catalyst for higher performance.