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Highly CO2 perm-selective metal-organic framework membranes through CO2 annealing post-treatment

Rui, Zebao, James, Joshua B., Lin, Y.S.
Journal of membrane science 2018 v.555 pp. 97-104
adsorption, anions, annealing, artificial membranes, carbon dioxide, carbonates, coordination polymers, hydrogen, mole fraction, permeability
Gas separation by metal-organic framework (MOF) membranes are still unsatisfactory due partly to unsatisfied separation characteristics caused by the trade-off between selectivity and permeability. Herein, we provide a facile post CO2 annealing method to remarkably improve both the permeance and separation factor of IRMOF-1 membranes for CO2 separation from CO2/H2 mixture. Post-treatment of the IRMOF-1 membrane by annealing at 100 °C under a high pressure CO2 stream deceases H2 permeance while increasing CO2 permeance, leading to simultaneous enhancement in both CO2/H2 separation factor from 721 up to 5781 and CO2 permeance from 5.67 × 10−7 up to 9.38 × 10−7 mol m−2 s−1 Pa−1 at CO2 molar fraction of 98%, feed pressure of 5 atm and 298 K. The unusual separation behavior is related to the enhanced CO2 adsorption selectivity over H2 and reduced CO2 affinity of the membrane due to the formation of surface carbonate anions caused by the CO2 treatment. The proposed gas atmosphere post-treatment strategy opens a window for designing next generation MOF-related gas separation membranes.