Selective methane oxidation by molecular iron catalysts in aqueous medium
Selective methane oxidation by molecular iron catalysts in aqueous medium
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DOI：
10.1038/s41586-023-05821-2
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发表时间：
2023-04-05
期刊：
影响因子：
64.8
通讯作者：
Kojima, Takahiko
中科院分区：
文献类型：
--
作者：
Fujisaki, Hiroto;Ishizuka, Tomoya;Kojima, Takahiko
使用天然气作为化学原料需要有效的氧化组成烷烃-主要是甲烷（1，2）。目前的工业过程使用高温高压下的蒸汽重整（3，4）来产生气体混合物，然后将其进一步转化为诸如甲醇的产品。分子Pt催化剂（5-7）也已用于将甲烷转化为甲醇（8），但由于过度氧化，它们的选择性通常较低-初始氧化产物往往比甲烷本身更容易氧化。在这里，我们表明，N-杂环卡宾连接的Fe-II配合物与疏水空腔捕获疏水甲烷基板从水溶液中，氧化后的Fe中心，释放亲水性甲醇产品回到溶液中。我们发现，增加疏水空腔的大小增强了这种效果，在3小时甲烷氧化反应期间，给出5.0 × 10（2）的转换数和83%的甲醇选择性。如果可以克服在水介质中处理甲烷所引起的运输限制，则这种捕获和释放策略提供了一种有效和选择性的方法来利用天然丰富的烷烃资源。
Using natural gas as chemical feedstock requires efficient oxidation of the constituent alkanes-and primarily methane(1,2). The current industrial process uses steam reforming at high temperatures and pressures(3,4) to generate a gas mixture that is then further converted into products such as methanol. Molecular Pt catalysts(5-7) have also been used to convert methane to methanol(8), but their selectivity is generally low owing to overoxidation-the initial oxidation products tend to be easier to oxidize than methane itself. Here we show that N-heterocyclic carbene-ligated Fe-II complexes with a hydrophobic cavity capture hydrophobic methane substrate from an aqueous solution and, after oxidation by the Fe centre, release a hydrophilic methanol product back into the solution. We find that increasing the size of the hydrophobic cavities enhances this effect, giving a turnover number of 5.0 x 10(2) and a methanol selectivity of 83% during a 3-h methane oxidation reaction. If the transport limitations arising from the processing of methane in an aqueous medium can be overcome, this catch-and-release strategy provides an efficient and selective approach to using naturally abundant alkane resources.