Chen Zhijie, Feng Liang, Liu Lingmei, Bhatt Prashant M, Adil Karim, Emwas Abdul-Hamid, Assen Ayalew H, Belmabkhout Youssef, Han Yu, Eddaoudi Mohamed
Langmuir. 2018 Dec 4;34(48):14546-14551. doi: 10.1021/acs.langmuir.8b03085. Epub 2018 Nov 26.
The discovery of appropriate synthetic reaction conditions for fabricating a stable zirconium-based molecular sieve (Zr-fum-fcu-MOF) with minimal defects and its utilization in the challenging separation of linear paraffins from branched paraffins is reported. The crystallinity and structural defects were modulated and adjusted at the molecular level by controlling the synthetic reaction conditions (i.e., amounts of modulators and ligands). The impact of molecular defects on the separation of n-butane from iso-butane was studied through the preparation, fine characterization, and performance evaluation of Zr-fum-fcu-MOFs with varying degrees of defects. Defect-rich Zr-fum-fcu-MOFs were found to have poor n-butane/iso-butane separation, mainly driven by thermodynamics, while Zr-fum-fcu-MOFs with fewer or minimal defects showed efficient separation, driven mainly by kinetics and full molecular exclusion mechanisms. The impact of intrinsic defects (i.e., missing organic or inorganic blocks) on the associated mechanisms involved in the separation of n-butane/iso-butane was evidenced through single-gas adsorption, mixed-gas column breakthrough experiments, and calorimetric studies. This investigation demonstrates, for the first time, the importance of controlling intrinsic defects to maintain the selective exclusion behavior of hydrocarbon isomers when using molecular sieves.
报道了用于制备具有最小缺陷的稳定锆基分子筛（Zr-fum-fcu-MOF）的合适合成反应条件的发现及其在从支链烷烃中挑战性地分离线性烷烃中的应用。通过控制合成反应条件（即调节剂和配体的量）在分子水平上调节和调整结晶度和结构缺陷。通过制备、精细表征和对具有不同程度缺陷的Zr-fum-fcu-MOFs的性能评估，研究了分子缺陷对正丁烷与异丁烷分离的影响。发现富含缺陷的Zr-fum-fcu-MOFs具有较差的正丁烷/异丁烷分离性能，主要由热力学驱动，而具有较少或最小缺陷的Zr-fum-fcu-MOFs表现出高效分离，主要由动力学和全分子排斥机制驱动。通过单气体吸附、混合气体柱穿透实验和量热研究，证明了固有缺陷（即缺失的有机或无机块）对正丁烷/异丁烷分离相关机制的影响。这项研究首次证明了在使用分子筛时控制固有缺陷以维持烃异构体选择性排斥行为的重要性。
