Direct oxidative carbonylation of methane to acetic acid via high-valent iron-oxo mediated water activation
Haonan Zhang (China University of Petroleum (East China))
Richard J. Lewis (Cardiff University)
A. Iulian Dugulan (TU Delft - RID/TS/Instrumenten groep, TU Delft - RST/Energy Materials)
Yang Li (China University of Petroleum (East China))
Shuai Wang (China University of Petroleum (East China))
Zhenxing Wang (Huazhong University of Science and Technology)
Jianrong Zeng (Chinese Academy of Sciences, Shanghai)
Nicholas F. Dummer (Cardiff University)
Yanyan Xi (China University of Petroleum (East China))
More Authors (External organisation)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
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.
help_outline