Enhanced 2-D MOFs nanosheets/PIM-PMDA-OH mixed matrix membrane for efficient CO2 separation

The PIMs−PIs membranes showed huge potential for CO2 separation, while suffered from low gas permeability due to small free volume. Due to the unique pore structure and ultra-high specific surface with nanoscale thickness, the metal organic frameworks (MOFs) nanosheets showed excellent gas separation performance with high gas permeance. In this work, the 2-D MOFs (Zn2(bim)4) nanosheets were introduced in PIM-PMDA-OH for increasing microstructure free volume by simply mixing the 2-D MOFs nanosheets colloidal suspension with polymer solution. The MOFs nanosheets fillers exhibited good compatibility with polymer matrix due to the uniform dispersion in the colloidal suspension, the MMMs showed no defect at high MOFs contents as 17.2 wt%. Benefitting from the excellent molecule sieve ability and chemical stability of 2-D MOFs nanosheets, the obtained MMMs exhibited significantly enhanced CO2 diffusion permeability and selectivity and operation stability thus efficient CO2 separation performance, the gas separation performance of CO2/CH4 exceeded the upper bound 2008. We believe this study of 2-D MOFs-based MMMs is meaningful for the further application of membrane technology in CO2 separation.