Direct conversion of CO2 with methane into chemicals over ZrO2/TiO2 catalysts

Abstract Direct conversion of CO2 with methane was studied over a selective catalyst to produce valuable chemicals. A ZrO2/TiO2 based catalyst was prepared by co-participation and wet impregnation methods. The catalyst was characterized by different techniques. The zirconia based titania catalyst showed larger particle size growth than the original TiO2 and the catalytic surface acidity increased by 4–9 times compared to the support. The Zr based on Ti co-precipitation catalyst showed stable framework but the catalyst structure was inactive under hydrogen reduction. On the other hand, the 5% Zr/Ti oxide impregnated catalyst has showed higher hydrogen reduction, resulting in the activation of the C–H bond of methane and reaction with CO2. The direct reaction of CO2 with methane indicated that a Langmuir-Hinshelwood mechanism was best explained based on the insertion reaction of carbon dioxide into methane. In the absence of carbon dioxide, the methyl species dimerised from methane to produce ethane gas. However, the presence of carbon dioxide in the reaction resulted in producing more acetic acid due to the insertion of the adsorbed CO2 into the methyl surface specie, followed by a hydrogenation reaction, which is more favourable than the dimerization reaction to produce ethane and ethylene.