Self-diffusion of mixed xylene isomers in ZIF-71 crystals dispersed in a polymer to form a hybrid membrane
Self-diffusion of mixed xylene isomers in ZIF-71 crystals dispersed in a polymer to form a hybrid membrane
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DOI：
10.1016/j.micromeso.2022.111960
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发表时间：
2022-05
影响因子：
5.2
通讯作者：
Amineh Baniani;Matthew P. Rivera;Ryan P. Lively;S. Vasenkov
中科院分区：
文献类型：
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作者：
Amineh Baniani;Matthew P. Rivera;Ryan P. Lively;S. Vasenkov
使用13 C脉冲场梯度（PFG）NMR来量化分散在Torlon聚合物中的沸石咪唑酯骨架-71（ZIF-71）晶体内的对二甲苯/邻二甲苯混合物的自扩散，以形成ZIF-71/Torlon混合基质膜（MMM）。还用ZIF-71晶体的松散填充床的床进行相应的参考PFG NMR测量。这项研究的动机是一个证明了潜在的ZIF为基础的MMM液体分离。选择性13 C同位素标记的每一个二甲苯异构体，以确保在混合物中的每一个异构体的自扩散率是独立和正确的测量。在296 K下，在不同的扩散时间下进行扩散测量。内ZIF自扩散系数在ZIF-71/Torlon MMM和相应的ZIF-71晶体床扩散时间的观察到的依赖性解释的外部晶体表面上的研究扩散过程的影响。对每种二甲苯异构体测量的自扩散率的时间依赖性的分析允许获得不受晶体表面效应干扰的ZIF内自扩散率以及所研究的山梨酸盐混合物的相应扩散选择性。报道的选择性约为4，表明所考虑的膜类型的有前途的分离行为。
13C pulsed field gradient (PFG) NMR was used to quantify self-diffusion of ap-xylene/o-xylene mixture inside zeolitic imidazolate framework-71 (ZIF-71) crystals dispersed in a Torlon polymer to form a ZIF-71/Torlon mixed-matrix membrane (MMM). The corresponding reference PFG NMR measurements with a bed of a loosely packed bed of ZIF-71 crystals were also performed. This study is motivated by a demonstrated potential of ZIF-based MMMs for liquid separations. Selective13C isotopic labelling of each xylene isomer was used to ensure that the self-diffusivity of each isomer in the mixture is measured independently and correctly. The diffusion measurements were performed at different diffusion times at 296 K. The observed dependencies of intra-ZIF self-diffusivities in ZIF-71/Torlon MMMs and the corresponding ZIF-71 crystal beds on diffusion time were explained by an influence of the external crystal surface on the studied diffusion process. Analysis of the time dependencies of the self-diffusivities measured for each xylene isomer allowed obtaining intra-ZIF self-diffusivities not perturbed by crystal surface effects as well as the corresponding diffusion selectivity for the studied sorbate mixture. The reported selectivity of around 4 demonstrates promising separation behavior of the considered membrane type.