Activation of thermodynamically stable feedstocks, selective conversion to value-added products, and catalyst stability considerations pose challenges to modern catalyst design, as all impose strict site requirements for atom-efficient turnovers. Here, we investigate perovskite oxides of chemical formula ABO3 with 12-fold coordinated alkaline-earth cations as A-sites and 6-fold coordinated transition metal cations as B-sites as tunable scaffolds for catalytic transition metal (Ru) active sites. Defined atomistic arrangement of isolated transition metal sites make these materials conducive for rigorous kinetic assessments to provide insight into how active site and/or reactor design contribute to efficient chemical processes. This work centers on the reaction of two potent greenhouse gases, methane (CH4) and carbon dioxide (CO2), to produce carbon monoxide (CO) and dihydrogen (H2). This dry reforming pathway furnishes stoichiometric H2:CO ratios of 1:1, which are suitable inlet feeds for Fischer-Tropsch processes. In conventional supported Ru systems, C—H bond activation is the sole rate-limiting step for methane conversion, with rates agnostic towards support chemical identities. In contrast, we observe a shift in mechanism unique to single-site transition metal cations ligated within a perovskite lattice. Further, Ru-doped systems exhibit higher stable methane turnover rates than those observed for supported systems that cannot be fully rationalized by metal dispersion effects. In all, versatile transition-metal perovskite oxide structures can be designed to constrain transition metal site oxidation states, electronic nature, and metal dispersion to satisfy site demands for a given chemistry.
