Direct Coupling of Methane and Carbon Dioxide on Tantalum Cluster Cations

Understanding molecular-scale reaction mechanisms is crucial for the design of modern catalysts with industrial prospect. Through joint experimental and computational studies, we investigate the direct coupling reaction of CH₄ and CO₂, two abundant greenhouse gases, mediated by Ta_1,4⁺ ions to form larger oxygenated hydrocarbons. Coherent with proposed elementary steps, we expose products of CH₄ dehydrogenation [Ta_1,4CH₂]⁺ to CO₂ in a ring electrode ion trap. Product analysis and reaction kinetics indicate a predisposition of the tetramers for C−O coupling with a conversion to products of CH₂O, whereas atomic cations enable C−C coupling yielding CH₂CO. Selected experimental findings are supported by thermodynamic computations, connecting structure, electronic properties, and catalyst function. Moreover, the study of bare Ta_1,4⁺ compounds indicates that methane dehydrogenation is a significant initial step in the direct coupling reaction, enabling new, yet unknown reaction pathways.