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Selective Methane Oxidation to Acetic Acid Using Molecular Oxygen over a Mono-Copper Hydroxyl Catalyst
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-03-10 , DOI: 10.1021/jacs.2c12042
Neha Antil 1 , Manav Chauhan 1 , Naved Akhtar 1 , Rahul Kalita 1 , Kuntal Manna 1
Affiliation  

Acetic acid is an industrially important chemical, produced mainly via carbonylation of methanol using precious metal-based homogeneous catalysts. As a low-cost feedstock, methane is commercially transformed to acetic acid via a multistep process involving energy-intensive methane steam reforming, methanol synthesis, and, subsequently, methanol carbonylation. Here, we report a direct single-step conversion of methane to acetic acid using molecular oxygen (O2) as the oxidant under mild conditions over a mono-copper hydroxyl site confined in a porous cerium metal–organic framework (MOF), Ce-UiO-Cu(OH). The Ce-UiO MOF-supported single-site copper hydroxyl catalyst gave exceptionally high acetic acid productivity of 335 mmolgcat–1 in 96% selectivity with a Cu TON up to 400 at 115 °C in water. Our spectroscopic and theoretical studies and controlled experiments reveal that the conversion of methane to acetic acid occurs via oxidative carbonylation, where methane is first activated at the copper hydroxyl site via σ-bond metathesis to afford Cu-methyl species, followed by carbonylation with in situ-generated carbon monoxide and subsequent hydrolysis by water. This work may guide the rational design of heterogeneous abundant metal catalysts for the activation and conversion of methane to acetic acid and other valuable chemicals under mild and environmentally friendly reaction conditions.

中文翻译:

在单羟基铜催化剂上使用分子氧将甲烷选择性氧化成乙酸

乙酸是一种工业上重要的化学品,主要通过使用贵金属基均相催化剂对甲醇进行羰基化生产。作为一种低成本原料,甲烷通过多步工艺在商业上转化为乙酸,包括能源密集型甲烷蒸汽重整、甲醇合成,以及随后的甲醇羰基化。在这里,我们报告了在温和条件下使用分子氧 (O 2 ) 作为氧化剂在多孔铈金属有机框架 (MOF) 中限制的单铜羟基位点上将甲烷直接单步转化为乙酸,Ce- UiO-Cu(OH)。Ce-UiO MOF 负载的单位点铜羟基催化剂提供了 335 mmol/g cat –1的极高乙酸生产率在 115 °C 的水中,Cu TON 高达 400,选择性为 96%。我们的光谱和理论研究以及对照实验表明,甲烷转化为乙酸是通过氧化羰基化发生的,其中甲烷首先通过 σ 键复分解在铜羟基位点被激活,得到 Cu-甲基物质,然后在原位进行羰基化- 产生一氧化碳并随后被水水解。这项工作可以指导合理设计多相丰富的金属催化剂,用于在温和和环境友好的反应条件下将甲烷活化和转化为乙酸和其他有价值的化学品。
更新日期:2023-03-10
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