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

Conversion of CO 2 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 CO 2 to CH 4, 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 La 2 O 3 . 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 CO 2 methanation, which is attributed to the high dispersion of metal particles and the better mass transfer performance of interconnected mesopores in the silica support.