Synthesis of fumed silica supported Ni catalyst for carbon dioxide conversion to methane

In this study, we report the synthesis of a fumed silica supported Ni-based catalyst for carbon dioxide conversion to methane. Ni/fumed-SiO2 was prepared by loading the active agent precursor solution on the high surface area fumed SiO2 through the wet impregnation technique. Thereafter, the resulting powder was dried and reduced under hydrogen flow at 750 degrees C for 3 h to get the desired active agent. The CO2 catalytic hydrogenation was performed using a flow reactor between 50 and 650 degrees C temperature, where it showed good catalytic activity and selectivity for methane. In addition, it is found to be highly stable under reaction conditions for 16 h time on stream. Fresh and used (after the stability test) catalyst samples were characterized using different techniques, such as XRD, TEM, SEM/EDX, to investigate the structural and morphological properties, and effect of exposure to reaction conditions on the catalysts. Furthermore, the reaction mechanism was investigated using in-situ DRIFT in the temperature range 50-450 degrees C. The results revealed the formation of formate species at early reaction stages, followed by CO that was detected as linearly adsorbed on Ni surface, and lastly methane formation. (c) 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.