School of Physical Science and Technology & Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, P. R. China.
Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain.
J Am Chem Soc. 2023 Mar 29;145(12):6628-6632. doi: 10.1021/jacs.2c12673. Epub 2023 Mar 6.
Zeolites are among the most important heterogeneous catalysts, widely employed in separation reaction, fine chemical production, and petroleum refining. Through rational design of the frameworks, zeolites with versatile functions can be synthesized. Local imaging of zeolite structures at the atomic scale, including the basic framework atoms (Si, Al, and O) and extra-framework cations, is necessary to understand the structure-function relationship of zeolites. Herein, we implemented electron ptychography into direct imaging of local structures of two zeolites, Na-LTA and ZSM-5. Not only all the framework atoms but also extra-framework Na cations with only 1/4 occupation probabilities in Na-LTA were directly observed. Local structures of ZSM-5 zeolites having guest molecules among channels with different orientations were also unraveled using different reconstruction algorithms. The approach presented here provides a new way to locally image zeolites structure, and it is expected to be an essential key for further studying and tuning zeolites active sites at the atomic level.
沸石是最重要的多相催化剂之一，广泛应用于分离反应、精细化学品生产和石油炼制。通过合理设计骨架，可合成具有多种功能的沸石。在原子尺度上对沸石结构进行局部成像，包括基本骨架原子（Si、Al 和 O）和骨架外阳离子，这对于理解沸石的结构-功能关系是必要的。在此，我们将电子相衬技术应用于两种沸石 Na-LTA 和 ZSM-5 的局部结构的直接成像。不仅直接观察到了所有的骨架原子，还观察到了 Na-LTA 中仅占据 1/4 位的骨架外 Na 阳离子。使用不同的重建算法还揭示了具有不同取向通道内客体分子的 ZSM-5 沸石的局部结构。本文提出的方法为沸石结构的局部成像提供了一种新方法，有望成为在原子水平上进一步研究和调变沸石活性位的关键。
