Ma Yao, Jue Melinda L, Zhang Fengyi, Mathias Ronita, Jang Hye Youn, Lively Ryan P
School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA, 30332, USA.
Angew Chem Int Ed Engl. 2019 Sep 16;58(38):13259-13265. doi: 10.1002/anie.201903105. Epub 2019 Aug 7.
Carbon molecular sieve (CMS) membranes are candidates for the separation of organic molecules due to their stability, ability to be scaled at practical form factors, and the avoidance of expensive supports or complex multi-step fabrication processes. A critical challenge is the creation of "mid-range" (e.g., 5-9 Å) microstructures that allow for facile permeation of organic solvents and selection between similarly-sized guest molecules. Here, we create these microstructures via the pyrolysis of a microporous polymer (PIM-1) under low concentrations of hydrogen gas. The introduction of H inhibits aromatization of the decomposing polymer and ultimately results in the creation of a well-defined bimodal pore network that exhibits an ultramicropore size of 5.1 Å. The H assisted CMS dense membranes show a dramatic increase in p-xylene ideal permeability (≈15 times), with little loss in p-xylene/o-xylene selectivity (18.8 vs. 25.0) when compared to PIM-1 membranes pyrolyzed under a pure argon atmosphere. This approach is successfully extended to hollow fiber membranes operating in organic solvent reverse osmosis mode, highlighting the potential of this approach to be translated from the laboratory to the field.
碳分子筛（CMS）膜因其稳定性、能够以实际外形尺寸进行规模化生产以及避免使用昂贵的支撑体或复杂的多步制造工艺，而成为分离有机分子的候选材料。一个关键挑战是创建“中等范围”（例如5-9埃）的微观结构，以实现有机溶剂的轻松渗透，并在尺寸相近的客体分子之间进行选择。在此，我们通过在低浓度氢气下对微孔聚合物（PIM-1）进行热解来创建这些微观结构。氢气的引入抑制了分解聚合物的芳构化，最终形成了明确的双峰孔网络，其超微孔尺寸为5.1埃。与在纯氩气气氛下热解的PIM-1膜相比，氢气辅助的CMS致密膜对二甲苯的理想渗透率显著提高（约15倍），对二甲苯/邻二甲苯选择性几乎没有损失（分别为18.8和25.0）。这种方法成功地扩展到了以有机溶剂反渗透模式运行的中空纤维膜，突出了该方法从实验室转化到实际应用的潜力。
