Ru Nanoparticle Supported by Mesoporous SiO_x and Pillared Montmorillonite: Suppressing Catalyst Inhibition in Carbon...

The utilization of anthropogenic CO₂ represents a critical strategy for closing the carbon cycle, particularly when coupled with renewable hydrogen. Here, we demonstrate a highly effective catalyst for CO₂ methanation based on Ru nanoparticles confined within mesoporous SiO_x-pillared montmorillonite (MMT). Introduction of Ru cations into the mesopores and subsequent hydrogen post-treatment yielded highly dispersed metallic Ru nanoparticles with a narrow size distribution centered at approximately 2 nm. Unlike conventional supported metal catalysts, which typically exhibit a pronounced decrease in reaction rate at high CO₂ conversion due to inhibition by byproducts such as H₂O and CO, the Ru/Pillared MMT catalyst sustained a high reaction rate even in the high-conversion regime. Although increasing the Ru particle size in conventional catalysts can alleviate such inhibition, this approach is generally accompanied by a substantial loss in Ru mass-specific activity. In contrast, the Ru/pillared MMT catalyst simultaneously achieves a high reaction rate at elevated CO₂ conversions and a high Ru-normalized activity, representing a catalytic performance that is rarely observed in conventional supported metal systems. These results highlight the critical role of mesoporous confinement within pillared MMT in mitigating inhibition effects while preserving efficient metal utilization in CO₂ hydrogenation catalysis.