La2O3–Modified Ni-Based Catalysts Supported on Ordered Mesoporous Silicas for CO2 Methanation

Conversion of CO2 into value-added chemicals is regarded as an effective way to reduce carbon emissions and improve the carbon recycling economy. In the process of hydrogenation of CO2 to CH4, nickel (Ni) has been extensively investigated due to its promising activity and easy availability. However, the inferior performance at low temperatures of Ni-based catalysts and the tendency of sintering at high temperatures lead to a rapid decline in activity, which hinders their large-scale applications. In this study, mesoporous silicas with highly ordered mesoporous structures but different pore symmetries and textural properties have been investigated as supports to synthesize Ni-based catalysts modified by La2O3. The effect of mesoporous symmetries and textural properties of the silica support on catalytic performance has been reasonably revealed. The catalysts supported on optimized silica with bicontinuous three-dimensional cubic pore symmetry exhibit considerably enhanced activity and stability in long-term CO2 methanation, which is attributed to the high dispersion of metal particles and the better mass transfer performance of interconnected mesopores in the silica support.