Chauhan Manav, Rana Bharti, Gupta Poorvi, Kalita Rahul, Thadhani Chhaya, Manna Kuntal
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, India.
Nat Commun. 2024 Nov 12;15(1):9798. doi: 10.1038/s41467-024-54101-8.
Direct oxidation of methane to valuable oxygenates like alcohols and acetic acid under mild conditions poses a significant challenge due to high C‒H bond dissociation energy, facile overoxidation to CO and CO and the intricacy of C-H activation/C-C coupling. In this work, we develop a multifunctional iron(III) dihydroxyl catalytic species immobilized within a metal-organic framework (MOF) for selective methane oxidation into methanol or acetic acid at different reaction conditions using O. The active-site isolation of monomeric Fe(OH) species at the MOF nodes, their confinement within the porous framework, and their electron-deficient nature facilitate chemoselective C‒H oxidation, yielding methanol or acetic acid with high productivities of and , respectively. Experiments and theoretical calculations suggest that methanol formation occurs via a Fe-Fe-Fe catalytic cycle, whereas CHCOH is produced via hydrocarboxylation of in-situ generated CHOH with CO and H, and direct CH carboxylation with CO.
在温和条件下将甲烷直接氧化为有价值的含氧化合物（如醇类和乙酸）面临着重大挑战，这是由于C‒H键的离解能高、容易过度氧化为CO和CO₂以及C-H活化/C-C偶联的复杂性。在这项工作中，我们开发了一种固定在金属有机框架（MOF）内的多功能铁（III）二羟基催化物种，用于在不同反应条件下使用O₂将甲烷选择性氧化为甲醇或乙酸。MOF节点处单体Fe(OH)物种的活性位点隔离、它们在多孔框架内的限制以及它们的缺电子性质促进了化学选择性C‒H氧化，分别以 和 的高生产率生成甲醇或乙酸。实验和理论计算表明，甲醇的形成通过Fe-Fe-Fe催化循环发生，而CH₃COOH是通过原位生成的CH₃OH与CO和H₂的氢羧化反应以及CH₃与CO的直接羧化反应产生的。
