Developing catalysts for the mild and selective oxidation of methane to methanol (CH₄-to-CH₃OH) is a challenging yet crucial endeavor for the industry. In this study, we propose a strategy to enhance the selective methane oxidation reaction, focusing on the crucial step of metal-oxo active-site formation. Our findings demonstrate that optimizing the spacing between active metal sites can facilitate efficient charge transfer from the metal sites to O₂, thereby kinetically enhancing O₂ activation and leading to the formation of highly reactive O (oxo) species capable of activating the methane C–H bond. Through the screening of different metals at varying metal site spacings, we find that the Co single atom exhibits favorable properties and performance, characterized by the duality of a low O₂ activation energy and the radical character of the formed metal-oxo species. Utilizing a Co single-atom catalyst dispersed on the UiO-66 MOF as a probe catalyst, we have showcased the potential of tailoring the active-site spacing to enhance the activity and selectivity toward methane oxidation to methanol. Notably, the newly designed catalyst surpasses the activity of a known catalyst, achieving an observable turnover frequency (>1 s^–1 site^–1) at 350 K while also enhancing its selectivity by inhibiting continuous methane dehydrogenation. This strategic approach could provide valuable insights for further exploration of MOF-supported single-atom catalysts or other support morphologies for the selective oxidation of CH₄ to CH₃OH with excellent activity in the gas phase.

中文翻译：

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定制单原子催化剂的活性位点间距以将 CH4 转化为 CH3OH：Co1/UiO-66 MOF 作为示例模型

开发用于甲烷温和选择性氧化为甲醇（CH ₄ -to-CH ₃ OH）的催化剂对于该行业来说是一项具有挑战性但又至关重要的努力。在这项研究中，我们提出了一种增强选择性甲烷氧化反应的策略，重点关注金属氧活性位点形成的关键步骤。我们的研究结果表明，优化活性金属位点之间的间距可以促进从金属位点到 O ₂的有效电荷转移，从而在动力学上增强 O ₂活化并导致形成能够活化甲烷 C– 的高反应性 O (oxo) 物种。 H键。通过筛选不同金属位点间距的不同金属，我们发现Co单原子表现出良好的性质和性能，其特点是低O ₂活化能和形成的金属-氧物种的自由基特征的二元性。利用分散在 UiO-66 MOF 上的 Co 单原子催化剂作为探针催化剂，我们展示了调整活性位点间距以提高甲烷氧化为甲醇的活性和选择性的潜力。值得注意的是，新设计的催化剂超越了已知催化剂的活性，在 350 K 下实现了可观察到的周转频率（>1 s ^–1 site ^–1），同时还通过抑制连续甲烷脱氢来提高其选择性。这种策略方法可以为进一步探索 MOF 负载的单原子催化剂或其他载体形态提供有价值的见解，用于将 CH ₄选择性氧化为CH ₃ OH，并在气相中具有优异的活性。