Ru Nanoparticle Supported by Mesoporous SiOx and Pillared Montmorillonite: Suppressing Catalyst Inhibition in Carbon Dioxide Hydrogenation.

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 SiOx-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.