Nanoporous ZIF-67 embedded polymers of intrinsic microporosity membranes with enhanced gas separation performance

In this study, novel kinds of MMMs were fabricated by incorporating ZIF-67 nanoparticles into polymers of intrinsic microporosity (PIM-1). ZIF-67 (Co substituted ZIF-8) displays stiffer Co-N bond as compared with the Zn-N bond in ZIF-8, which might led to the slightly smaller effective pore aperture of ZIF-67. Good compatibility between ZIF-67 nanoparticles and PIM-1 matrix rendered ideal interfacial morphology. The intrinsic separation performance of ZIF-67 was estimated from our experimental separation results based on the Maxwell model. The calculation demonstrated its superior CO2/CH4 selectivity of 45, which is twice compared with that of ZIF-8, supporting the high molecular sieving efficiency of PIM-1/ZIF-67 MMMs. Particularly, the CO2 and H2 permeability increased by 15.1% and 59.6% for PIM-1 membrane with 20 wt% ZIF-67 loading, meanwhile CO2/CH4 and H2/CH4 selectivity increased by 34.4% and 86.96%, respectively. The strategy of incorporating highly selective ZIFs into polymers of intrinsic microporosity may have promising potential in fabricating high performance membranes for efficient gas separation.