Abstract

The catalytic activity of glutathione-stabilized gold thiolate nanoclusters (1–2 nm) in the oxidation of methane with H₂O₂ and air oxygen in aqueous medium at 70°C in 30 atm CH₄ was studied. The ratio and yield of the oxidation products CH₃OH and CH₃OOH depends on the content of H₂O₂ and oxygen in the reactor. At increased partial pressure of oxygen, the total yield of products increases compared with the total yield of independent oxidations with H₂O₂ or O₂ at 5 atm of air, but decreases at 10 atm. A molecular mechanism of methane oxidation was proposed, which describes well the kinetic curves of accumulation and consumption of CH₃OH and CH₃OOH and the effect of oxygen on their yield. A molecular model of active site was proposed based on the literature data about the structure of glutathione-stabilized Au₂₅ clusters and the results of quantum chemical modeling. The experiments with re-introduction of the gas phase and renewal of the H₂O₂ content demonstrated 100% conservation of the catalytic activity. The yield of CH₃OH reached 60 mol per mole of Au₂₅ clusters.

中文翻译：

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谷胱甘肽稳定的金纳米团簇存在下氧对过氧化氢甲烷氧化甲烷转化为甲醇的影响

摘要

研究了谷胱甘肽稳定的硫醇金纳米簇（1-2 nm）在H ₂ O ₂和空气中的氧在70°C的30 atm CH _4的水介质中氧化甲烷的催化活性。氧化产物CH ₃ OH和CH ₃ OOH的比例和产率取决于反应器中H ₂ O ₂和氧气的含量。在氧气分压升高的情况下，与使用H ₂ O ₂或O ₂进行独立氧化的总产率相比，产物的总产率提高了空气在5 atm时，但在10 atm时降低。提出了甲烷氧化的分子机理，它很好地描述了CH ₃ OH和CH ₃ OOH的积累和消耗的动力学曲线以及氧对其收率的影响。基于谷胱甘肽稳定的Au ₂₅团簇结构的文献数据和量子化学建模的结果，提出了一个活性位点的分子模型。重新引入气相和更新H ₂ O ₂含量的实验证明了催化活性的100％保留。CH ₃ OH的产率达到每摩尔Au ₂₅簇60摩尔。