Hailong Zhang, Richard J. Lewis, A. Iulian Dugulan, Yang Li, Shuai Wang, Zhenxing Wang, Jianrong Zeng, Nicholas F. Dummer, Yanyan Xi, Yunyun Li, Thomas E. Davies, Mingbo Wu, Graham J. Hutchings, Wenting Wu
Abstract Direct conversion of CH 4 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 CH 4 and H 2 O activation through a high-valent-metal mediated radical mechanism, enabling selective CH 3 COOH synthesis. In-situ infrared, operando Mössbauer spectroscopy, and quasi in-situ high-field EPR reveal that O 2 oxidizes Rh and Fe to high valence states. Rh (III) activates CH 4 to •CH 3 , while Fe (IV) = O dissociates H 2 O into •OH through a truncated water-gas shift pathway. •OH rapidly reacts with CO to form •COOH intermediates, which couples with •CH 3 within the zeolite to yield CH 3 COOH. This dual-site strategy circumvents kinetic limits of conventional water-gas shift and CO insertion steps. The catalyst achieves 18.2 mmol g cat -1 h -1 CH 3 COOH 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.