Intrazeolite CO Methanation by Small Ruthenium Carbonyl Complexes: Translation from Free Clusters into the Cage

Abstract

Catalytic CO methanation represents an important reaction to improve the feed gas quality for hydrogen fuel cells. Previously, the large potential of small bare and ligated ruthenium clusters as highly selective and active catalysts has been shown by employing gas phase clusters as model systems. Now, density functional theory (DFT) calculations are employed to demonstrate the possibility to translate the gas phase CO methanation reaction mediated by a ligated Ru4(CO)13H2+ complex into the framework of a ZSM‐5 zeolite. Such a translation, manifested by a reaction pathway which is mechanistically and energetically similar to the gas phase analogue, is possible since the zeolite framework does not influence the reactive center. Furthermore, we reveal the important role of the CO ligand environment in protecting the Ru4+ metal core from formation of bonds with the zeolite and in the creation of the reactive center by promoting the cooperatively enhanced adsorption and dissociation of H2.