Constructing the highly efficient Ni/ZrO2/SiO2 catalyst by a combustion-impregnation method for low-temperature CO2 methanation

CO2 methanation is conducive to the storage of renewable electricity and the utilization of CO2. Exploiting highly efficient Ni-based catalysts with a simple method is of significance for this reaction. To achieve an excellent low-temperature activity, the attention is focused on the small Ni particles and ZrO2 promoter in this work, which can increase the amounts of H2 and CO2 active sites. Firstly, the simple combustion-impregnation method was employed, forming small Ni particles (about 6 nm). More metal-support interface and increased basicity could be generated in the meantime. Hence, the higher H2 dissociation and CO2 adsorption ability were attained. Secondly, ZrO2 serving as a promoter was beneficial to the formation of oxygen vacancies, which played an important role in CO2 activation and CH4 formation. These oxygen vacancies could weaken the CO bonds, improving the CO2 activation. In addition, they might serve as the H reservoir, increasing the H2 adsorption capacity. Because of the H spillover effect from Ni to ZrO2, the activated H atoms on Ni could react with activated CO2 to generate CH4. Therefore, with more active sites for H2 and CO2 activation, the Ni/ZrO2-COM catalyst exhibited the excellent catalytic performance at 300 °C. This work is of great significance in developing highly efficient Ni-based catalysts at low temperatures for CO2 methanation with a facile method.