Methane activation on metal oxide nanoparticles: spectroscopic identification of reaction mechanism

Currently, there is a lack of detailed knowledge about methane (CH4) reactions on metal oxide surfaces. This reaction involves in different processes such as chemical looping combustion and catalytic carbon dioxide (CO2) reforming of CH4. In this study, in situ diffuse reflectance infrared Fourier transform spectroscopy was used to investigate CH4 reaction on three transition metal oxides (CoO, CuO, and α-Fe2O3) which are commonly used in these processes at temperatures ranging from 100 °C to 700 °C. The results show that CH4 is adsorbed on the metal oxide surfaces as methoxy and formate, and then the methoxy group reacts with the metal oxide lattice oxygen forming bicarbonate. Under the effect of the used reaction temperature, the bicarbonate decomposes to CO2 and water vapor.