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<p>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.</p>

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Direct oxidative carbonylation of methane to acetic acid via high-valent iron-oxo mediated water activation

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月7日

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  • Haonan 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

摘要

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.