Unlocking CO2 methanation potential of mesoporous Ni-MCM-48

Abstract

CO₂ methanation is a significant pathway to store excess energy produced in power-to-gas systems. While the process has received much attention, low-cost heterogeneous catalysts with high efficiency and stability for selective CO₂ conversion are a highly desired research pursuit. Herein, we report the direct synthesis of Ni-substituted highly ordered 3D mesoporous MCM-48 silica (Ni-MCM-48) with a well-ordered porous structure and high specific surface areas (748–1092 m² g⁻¹). The substitution of Ni into the silica framework resulted in an apparent increase in the mesopore size, and uniform distribution of Ni atoms revealed through the microscopy images. XPS and UV-Vis DRS results indicate the presence of Ni-O-Si bonding, suggesting the interaction between the Ni and silica framework. When investigated for CO₂ methanation, Ni-MCM-48 with the n_Si/n_Ni ratio of 15 (15Ni-MCM-48) exhibited the best catalytic activity of 68.1 % conversion of CO₂ at the GHSV of 30,000 mL h⁻¹ g⁻¹_catalyst and 90.6 % selectivity in a reactant gas mixture of 5CO₂/20H₂/75N₂ mL/min. The catalyst also exhibited good cycling stability and enhanced mass transfer kinetics, which is attributed to the robust nature of the incorporated Ni into the silica framework. The obtained catalytic results are promising and worthy of further exploration to expand their reach to other catalytic applications.