Hou Qianqian, Zhou Sheng, Wei Yanying, Caro Jürgen, Wang Haihui
School of Chemistry and Chemical Engineering, South China University of Technology, 510640 Guangzhou, China.
Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstrasse 3A, 30167 Hannover, Germany.
J Am Chem Soc. 2020 May 27;142(21):9582-9586. doi: 10.1021/jacs.0c02181. Epub 2020 May 18.
Separation is one of the most energy-intensive processes in the chemical industry, and membrane-based separation technology helps to reduce the energy consumption dramatically. Supported metal-organic framework (MOF) layers hold great promise as a molecular sieve membrane, yet only a few MOF membranes showed the expected separation performance. The main reasons include e.g. nonselective grain boundary transport or the flexible MOF framework, especially the inevitable linker rotation. Here, we propose a crystal engineering strategy that balances the grain boundary structure and framework flexibility in Co-Zn bimetallic zeolitic imidazolate framework (ZIF) membranes and exploit their contributions to the improvement of membrane quality and separation performance. It reveals that a good balance between the two trade-off factors enabled a "sweet spot" that offers the best CH/CH separation factor up to 200.
分离是化学工业中能耗最高的过程之一，而基于膜的分离技术有助于大幅降低能耗。负载型金属有机框架（MOF）层作为分子筛膜具有很大的潜力，但只有少数MOF膜表现出预期的分离性能。主要原因包括例如非选择性的晶界传输或柔性的MOF框架，特别是不可避免的连接体旋转。在此，我们提出一种晶体工程策略，该策略平衡了Co-Zn双金属沸石咪唑酯框架（ZIF）膜中的晶界结构和框架柔性，并利用它们对提高膜质量和分离性能的贡献。结果表明，两个权衡因素之间的良好平衡产生了一个“最佳点”，该点提供高达200的最佳CH/CH分离因子。
