Carbon molecular sieve membranes fabricated at low carbonization temperatures with novel polymeric acid porogen for light gas separation

Carbon molecular sieve (CMS) membranes is promising for small gas molecules (e.g., H-2 and He) separation from big molecules (e.g., CH4, N-2 and CO2). However, conventional CMS membranes need high carbonization temperatures (e.g., >800 degrees C) to ensure both high gas permeability and selectivity. In the present work, the introduction of a novel pore generator (porogen) into the Troger's base polymer precursor, allowed the considerable reduction of carbonization temperature from similar to 800 degrees C to similar to 400 degrees C. Under optimized conditions, the obtained CMS membranes presented a H-2 permeability of 675.0 Barrer with a H-2/CH4 and H-2/N-2 selectivity of 678.3 and 297.1, He permeability of 400.1 Barrer with He/CH4 and He/N-2 selectivity of 405.6 and 176.6, respectively, which is much higher than the Upper Bound 2019. In addition, it is found that the porogen used in this work could also work in different materials, including Pebax and polyimides, which makes this method promising in CMS membrane fabrication.