Highly active Ni/CeO2/SiO2 catalyst for low-temperature CO2 methanation: Synergistic effect of small Ni particles and optimal amount of CeO2

CO2 methanation is of great significance to CO2 utilization. However, it is challenging to prepare Ni-based catalysts with superior low-temperature activity via a simple method. In this work, a highly active Ni/CeO2/SiO2 catalyst is developed by a combustion-impregnation method, and the synergistic effect of active sites for H-2 and CO2 activation are studied. The research results show that highly dispersed Ni particles (6 nm) are obtained by this method with an instantaneous reaction. As a result of the increased number of Ni active sites, the catalyst exhibits improved catalytic activity. Moreover, addition of CeO2 promoter further improves the low-temperature activity. First, it enhances the catalyst reducibility, creating more Ni active sites for H-2 dissociation. Second, the surface oxygen vacancies formed on CeO2 facilitate CO2 activation. Therefore, the best performance of 63% CO2 conversion and 99% CH4 selectivity at 250 degrees C is achieved on the Ni-5Ce catalyst with small Ni particles and optimal amount of CeO2 promoter. With higher CeO2 content, Ni-7.5Ce catalyst displays decreased catalyst reducibility and catalytic activity. Therefore, it can be concluded that a proper ratio between both types of sites is crucial for CO2 methanation.

Automated summary

A highly active Ni/CeO2/SiO2 catalyst is developed by a combustion-impregnation method for CO2 methanation. The addition of CeO2 promoter enhances the catalyst reducibility and facilitates CO2 activation. The optimal performance is achieved on the Ni-5Ce catalyst with small Ni particles and an optimal amount of CeO2 promoter.