Li Dejie, Han Ying, Li Deqiang, Kang Qi, Shen Dazhong
College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan, 250014, P. R. China.
National Engineering Research Center for Colloidal Materials and School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China.
Sci Rep. 2020 Feb 20;10(1):3010. doi: 10.1038/s41598-020-59871-x.
Computational simulation methods are used for characterizing the detailed attachment, diffusion and desorption of halogen vapor molecules in zeolitic imidazolate framework-8 (ZIF-8). The attachment energies of Cl, Br and I are -55.2, -48.5 and -43.0 kJ mol, respectively. The framework of ZIF-8 is disrupted by Cl, which bonds with Zn either on the surface or by freely diffusing into the cage. A framework deformation on the surface of ZIF-8 can be caused by the attachment of Br, but only reorientation of the 2-methylimidazolate linkers (mIms) for I. In diffusion, the halogen molecules have a tendency to vertically permeate the apertures of cages followed with swing effect implemented by the mIms. Larger rotation angles of mIms are caused by Br because of its stronger interaction with mIms than I. A maximum of 7 Br or 5 I molecules can be accommodated in one cage. Br are clinging to the mIms and I are arranged as crystal layout in the cages, therefore in desorption processes molecules attached to the surface and free inside are desorbed while some remained. These results are beneficial for better understanding the adsorption and desorption processes of halogen vapors in the porous materials.
计算模拟方法用于表征卤化氢气体分子在咪唑基沸石骨架-8（ZIF-8）中的详细吸附、扩散和解吸过程。氯、溴和碘的吸附能分别为-55.2、-48.5和-43.0kJ/mol。氯会破坏ZIF-8的骨架，它会与表面的锌结合或自由扩散到笼中。溴的吸附会导致ZIF-8表面的骨架变形，而碘只会导致2-甲基咪唑连接体（mIms）的重新定向。在扩散过程中，卤化氢分子倾向于垂直渗透笼的孔道，并伴随着mIms产生的摆动效应。由于溴与mIms的相互作用比碘更强，所以溴会导致mIms产生更大的旋转角度。一个笼中最多可容纳7个溴分子或5个碘分子。溴附着在mIms上，而碘在笼中呈晶体排列，因此在解吸过程中，附着在表面和笼内自由的分子会被解吸，但仍会有一些残留。这些结果有助于更好地理解多孔材料中卤化氢气体的吸附和解吸过程。
