Direct oxidative carbonylation of methane to acetic acid via high-valent iron-oxo mediated water activation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41794868.
- Also identified by DOI 10.1038/s41467-026-70339-w and PMC identifier 13096338.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Direct conversion of CH<sub>4</sub> 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<sub>4</sub> and H<sub>2</sub>O activation through a high-valent-metal mediated radical mechanism, enabling selective CH<sub>3</sub>COOH synthesis. In-situ infrared, operando Mössbauer spectroscopy, and quasi in-situ high-field EPR reveal that O<sub>2</sub> oxidizes Rh and Fe to high valence states. Rh<sup>(III)</sup> activates CH<sub>4</sub> to •CH<sub>3</sub>, while Fe<sup>(IV)</sup> = O dissociates H<sub>2</sub>O into •OH through a truncated water-gas shift pathway. •OH rapidly reacts with CO to form •COOH intermediates, which couples with •CH<sub>3</sub> within the zeolite to yield CH<sub>3</sub>COOH. This dual-site strategy circumvents kinetic limits of conventional water-gas shift and CO insertion steps. The catalyst achieves 18.2 mmol g<sub>cat</sub><sup>-1</sup> h<sup>-1</sup> CH<sub>3</sub>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.