Long-term pure- and mixed-gas performance of carbon molecular sieve membranes derived from a tetraphenylethylene-based ladder polymer of intrinsic microporosity (TPE-PIM) for propylene/propane separation

作者：Fawwaz Elahi, Yingge Wang, Khalid Hazazi, Vikas Kumar, Marcel Balçık, Nimer Wehbe, Feng Xu, Ingo Pinnau · 发表于：Journal of Membrane Science · 年份：2024 · DOI：10.1016/j.memsci.2024.123255 · 被引用次数：13 · 研究领域：Membrane Separation and Gas Transport、Muon and positron interactions and applications、Fuel Cells and Related Materials

Continuous long-term evaluation of propylene and propane permeation through narrow slit carbon molecular sieve (CMS) membranes is essential for an in-depth study of their steady-state separation performance. CMS membranes are characterized by finely tuned ultramicroporous structures, exceptional thermal and chemical stability, and hold great promise for the energy-intensive separation of propylene and propane. However, the gradual changes in their performance over time due to penetrant-induced structural chain rearrangements have often been overlooked. In this study, we prepared CMS membranes using a polymer of intrinsic microporosity (PIM) with a highly aromatic tetraphenylethylene (TPE) based building block. The presence of bulky and sterically hindered TPE repeat units renders this polymer an excellent precursor for the fabrication of high-performance CMS membranes. The TPE-PIM-based precursor underwent pyrolysis at temperatures ranging from 550 to 700 °C for 1 h. Pure- and mixed-gas permeation tests were accompanied by various characterization techniques to assess the carbonization state of the CMS materials. The CMS pyrolyzed at 700 °C exhibited a decline in pure-gas C 3 H 6 /C 3 H 8 selectivity from an initial value of 300 to 161 at steady state over a 20-day period. Even more notable, under equimolar mixed-gas feed conditions, the isotropic CMS film displayed a substantial C 3 H 6 /C 3 H 8 selectivity reduction from 214 to 62 over a 24-day period. This performance decl...