Direct conversion of CH4 into value-added chemicals is impeded by the inert C-H bonds and inefficient C-C coupling. We report a spatially separated Rh-O-Fe active-site architecture that decouples CH4 and H2O activation through a high-valent-metal mediated radical mechanism, enabling selective CH3COOH synthesis. In-situ infrared, operando Mössbauer spectroscopy, and quasi in-situ high-field EPR reveal that O2 oxidizes Rh and Fe to high valence states. Rh(III) activates CH4 to •CH3, while Fe(IV) = O dissociates H2O into •OH through a truncated water-gas shift pathway. •OH rapidly reacts with CO to form •COOH intermediates, which couples with •CH3 within the zeolite to yield CH3COOH. This dual-site strategy circumvents kinetic limits of conventional water-gas shift and CO insertion steps. The catalyst achieves 18.2 mmol gcat-1 h-1 CH3COOH with 92% selectivity and 100-hour stability in continuous operation. This study establishes radical decoupling enabled by high-valent metal sites as a design principle for selective alkane oxidation.
Zhang et al. (Sat,) studied this question.