School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Dr. NW, Atlanta, GA, 30332, USA.
Angew Chem Int Ed Engl. 2023 Jul 3;62(27):e202303915. doi: 10.1002/anie.202303915. Epub 2023 May 25.
Carbon molecular sieve (CMS) membranes are attractive candidates to meet requirements for challenging gas separations. The added ability to maintain such intrinsic properties in an asymmetric morphology with a structure that we term a "Pseudo Wheel+Hub & Spoke" asymmetric form offers new opportunities. For CMS membrane, specifically, the structure provides both selective layer support and low flow resistance even for high feed pressures and fluxes in CO removal from natural gas. This capability is unavailable to even rigid glassy polymers due to the much higher modulus of CMS materials. Combining precursor asymmetric hollow fiber formation and optimized pyrolysis creates a defect free CMS proof-of-concept membrane for this application. Facile formation of the sheath-core spun precursor with a 6FDA-DAM sheath and Matrimid® core also avoids the need to seal defects before or after the carbonization of the precursors. The composite CMS membrane shows CO /CH (50 : 50) mixed gas feed with an attractive CO /CH selectivity of 64.3 and CO permeance of 232 GPU at 35 °C. A key additional benefit of the approach is reduction in use of the more costly high performance 6FDA-DAM in a composite sheath-core CMS membrane with the "Pseudo Wheel+Hub & Spoke" structure.
碳分子筛 (CMS) 膜是满足挑战性气体分离要求的有吸引力的候选材料。在具有我们称之为“伪轮+轮毂与辐条”不对称形式的结构中保持这种固有特性的能力提供了新的机会。对于 CMS 膜，特别是该结构为选择性层提供了支撑，并且即使在高进料压力和通量下，从天然气中去除 CO 时也具有低流动阻力。由于 CMS 材料的模量高得多，即使是刚性玻璃状聚合物也无法实现这种能力。通过先驱体不对称中空纤维的形成和优化的热解，为该应用创造了一种无缺陷的 CMS 概念验证膜。通过 6FDA-DAM 鞘和 Matrimid®芯的简便纺丝形成鞘芯复合纺丝前体，也避免了在先驱体碳化之前或之后需要密封缺陷的问题。该复合 CMS 膜在 35℃下显示出 CO/CH（50:50）混合气进料，具有吸引人的 CO/CH 选择性 64.3 和 CO 渗透率 232 GPU。该方法的一个关键额外好处是在具有“伪轮+轮毂与辐条”结构的复合鞘芯 CMS 膜中减少了更昂贵的高性能 6FDA-DAM 的使用。
