(705f) Tailoring Ultramicropores in Hybrid Carbon Molecular Sieve Membranes to Achieve High H2 Selectivity | AIChE

(705f) Tailoring Ultramicropores in Hybrid Carbon Molecular Sieve Membranes to Achieve High H2 Selectivity


Hu, L. - Presenter, University At Buffalo
Bui, V., University at Buffalo
Subramanian, A., Stony Brook University
Kisslinger, K., Brookhaven National Laboratory
Zhu, L., National Energy Technology Laboratory
Fan, S., University of Colorado
Ding, Y., University of Colorado Boulder
Nam, C. Y., Brookhaven National Laboratory
Lin, H., University of Buffalo, State University of New Yor
Porous carbon materials with tunable pore structures have attracted substantial attention for membrane separation. Particularly, carbon molecular sieve (CMS) membranes with micropores (7 to 20 Å) that promote gas transport and ultramicropores (7 to 20 Å) derived from controlled pyrolysis of polymer precursors that confer strong size-sieving ability, have emerged for gas pair separation, including CO2/CH4, olefin/paraffin. However, rare CMS membranes have high selectivity for H2/gas separation due to small molecular size of H2. Here, we report advanced CMS membranes derived from a supramolecular mixed matrix network (SMMN) with high H2 selectivity against other gases including CO2, N2, CH4, and C2H6. Specifically, ZIF-8/polybenzimidazole (PBI) SMMN containing crystalline ZIF-8 and amorphous Zn/imidazole coordination on PBI chains was prepared via the in-situ ZIF-8 growth in PBI. With porous ZIF-8 promoting gas transport and Zn/imidazole coordination cross-linking PBI chains and then enhancing size-sieving ability, ZIF-8/PBI SMMN displayed both increased H2 permeability and H2/CO2 selectivity. Then, the SMMN was carbonized from 400 to 900 ℃. Compared to PBI/CMS prepared at same temperatures, SMMN/CMS films exhibit both higher H2 permeability and selectivity, even far surpassing Robeson’s upped bounds 2008. It can be attributed to Particularly, SMMN/CMS carbonized at 900 ℃ exhibited H2/CO2 selectivity of 220 at 70 ℃, higher than those of other leading membrane materials. This study opens up a new approach to design advanced CMS materials for H2 separation and other applications.