Sharply promoted CO₂ diffusion in a mixed matrix membrane with hierarchical supra-nanostructured porous coordination polymer filler

Mixed matrix membranes incorporated with porous coordination polymers (PCP) fillers have been considered as the most promising platform to achieve highly efficient gas separation, where the gas diffusion channel can be facilely designed and engineered, as well as the resistance of general rule of trade-off between selectivity and permeability. In this study, a novel mixed matrix membrane that contains chemically robust CeBTB filler with hierarchical supra-nanostructure has been established via systematic optimization. The analysis of gas permeation experiment and calculated diffusion coefficient describes that rich micro- and meso-pore of the CeBTB fillers provide unique gas transmission channel, which enable faster CO₂ permeability, as well as better CO₂/CH₄ selectivity. The wrapped CeBTB fillers by polymer segments demonstrated positive effect on the reduction of membrane plasticization at high pressure. More importantly, the membrane with 10 wt% CeBTB exhibited ultra-excellent CO₂/CH₄ separation not only in the dry state (P_CO2 = 1150 barrer, S = 37.4), but also along with moisture (P_CO2 = 892 barrer, S = 37.4). Importantly, these values far exceed the Robeson upper-bound which indicates the great potential for feasible application.