甲烷是天然气的主要成分，将甲烷直接转化为更有价值的乙烯一直是科学家们努力的方向，而甲烷氧化偶联反应（OCM）被认为是实现这一转化的有前景的途径。然而，目前OCM反应存在C2产物（主要是乙烯和乙烷）产率低的问题，并且对于催化剂设计的反应机理了解不足，这阻碍了其工业化应用。在一项新的研究中，科学家们提出了一种表面几何修饰策略来提高OCM反应的性能。他们将单个镧（La）原子掺入到氧化镁（MgO）表面，形成了一种独特的La - O - Mg“弹弓”几何结构。由于镧原子半径大，且其化合价与镁不匹配，这种结构能显著激活表面晶格氧。被激活的氧物种会与甲烷发生反应，从而启动OCM反应。反应产生的氧空位会迅速被氧气补充，这样既能持续提供活性氧，又能保持单个镧原子的结构完整性。科学家们利用先进的原位环境电子显微镜和电子能量损失谱技术实现了对这些过程的研究。值得注意的是，与缺乏活性氧物种的负载在MgO上的La₂O₃颗粒相比，La - O - Mg“弹弓”几何结构使C2产物产率提高了一倍，并且显著提升了单原子镧催化剂（SA - La/MgO）的转化频率。这项研究揭示了大幅提高OCM反应性能的新机制，强调了在催化剂设计中进行原子尺度几何和电子修饰的重要性。

期刊

ACS Central Science

标题

Active Slingshot Geometry Site on Single-Atom La Catalyst Largely Promotes Oxidative Methane Coupling

作者

Lizhuo Wang, Liwei Cao, Ang Li, Wenjie Yang, Wei Li, Xiaozhou Liao, Xiaodong Han, Jun Huang

摘要

progresses, OCM’s industrial implementation has been hampered by low C2 yields and insufficient understanding of the reaction mechanism for catalyst design. In this study, we present a surface geometric modification strategy to enhance OCM performance. Single La atoms incorporated onto MgO surface (SA-La/MgO) form a unique La–O–Mg “slingshot” geometry. This configuration, driven by the large atomic radius of La and its valency mismatch with Mg, significantly activates surface lattice oxygen. These activated oxygen species initiate the OCM by reacting with methane, while the resulting oxygen vacancies are rapidly replenished by dioxygen, sustaining active oxygen supply and preserving the structural integrity of single La atoms. These processes are realized by state-of-the-art in situ environmental electron microscopy and electron energy loss spectroscopy. Remarkably, the La–O–Mg “slingshot” geometry doubles C2 yields and significantly elevates the turnover frequency of SA-La/MgO compared to La2O3 particles on MgO, which lacks such active oxygen species. This work discovers a new mechanism for largely enhancing the OCM performance, emphasizing the importance of atomic-scale geometric and electronic modifications in catalyst design.

原文链接

https://pubs.acs.org/doi/10.1021/acscentsci.5c01016

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静远嘲风-南京（MY Scimage） 成立于2007年，嘲风取自中国传统文化中龙生九子，子子不同的传说，嘲风为守护屋脊之瑞兽，喜登高望远；静远取自成语“宁静致远”，登高莫忘初心，远观而不可务远。

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