Effective aperture tuning of a zeolitic-imidazole framework CdIF-1 by controlled thermal amorphization
Effective aperture tuning of a zeolitic-imidazole framework CdIF-1 by controlled thermal amorphization
复制标题
通过受控热非晶化有效调节沸石-咪唑骨架 CdIF-1 孔径
DOI：
10.1039/d1ta10706b
复制
发表时间：
2022
影响因子：
11.9
通讯作者：
Jeong, Hae-Kwon
中科院分区：
文献类型：
--
作者：
Park, Sunghwan;Jeong, Hae-Kwon
钠沸石-咪唑骨架(ZIF)因其有效孔径适合于小型气体分离而显示出巨大的潜力。因此，在调节它们的有效孔径大小以控制和增强它们的分子筛分性能方面已经做出了许多努力。在这里，我们提出了一种基于热非晶化的新策略来微调Cd取代的ZIF-8类似物--CdIF-1的有效孔径。在筛选的几个ZIF-8类似物中，发现唯一可以热非晶化的是CdIF-1。控制的非晶化降低了长程结构有序性，同时保持了短程有序性，从而系统地致密化了ZIF结构，从而影响了它的有效孔径。同时发现，非晶化增强了骨架的柔韧性，在273K以上形成了可访问的孔道。与晶态相比，部分非晶化的CdIF-1分子筛对n-C4H10/i-C4H10的扩散和吸附选择性有显著提高(分别为1.5C4H10和1.1→40.7和1.1→4.9)，这可能是由于非晶化诱导了其有效孔径的调整。
Sodalite zeolitic-imidazole frameworks (ZIFs) show great potential due to their effective aperture sizes suitable for small gas separations. Numerous efforts have, therefore, been made in tuning their effective aperture sizes to control and enhance their molecular sieving properties. Herein, we present a new strategy to finely tune the effective aperture size of CdIF-1, a cadmium-substituted ZIF-8 analogue, based on thermal amorphization. Among several ZIF-8 analogues screened, CdIF-1 was found to be the only one that could be thermally amorphized. The controlled amorphization reduced the long-range structural order while preserving the short-range order, thereby systematically densifying the ZIF structure and consequently affecting its effective aperture. Meanwhile, it was found that amorphization enhanced the flexibility of the framework, resulting in accessible pores at temperatures above 273 K. As compared to its crystalline counterpart, partially amorphized CdIF-1 showed significantly improved diffusion and adsorption selectivities of n-C4H10/i-C4H10 (i.e., 1.5 → 40.7 and 1.1 → 4.9, respectively), likely due to the amorphization-induced tuning of its effective aperture size.