Matrix effect of mixed‐matrix membrane containing CO₂‐selective MOFs

Facilitated mixed‐matrix membranes (MMMs) containing Cu‐metal organic frameworks (Cu‐MOFs) with high CO 2 selectivity on an asymmetric polysulfone support were fabricated and examined the effect of gas separation performance using different matrices. An amorphous poly(2‐ethyl‐2‐oxazoline) (POZ) and semicrystalline poly(amide‐6‐b‐ethylene oxide) (PEBAX ® MH 1657) block copolymer were chosen as the polymeric matrix and the effect of the matrix on CO 2 separation for MMMs containing Cu‐MOFs was investigated. The interaction of CO 2 in different matrix was investigated theoretically using the density functional theory method, and it was found that the amide segment in PEBAX would contribute more to the CO 2 solubility than ether segment. The morphological changes were investigated by differential scanning calorimetry, field emission scanning electron microscope and X‐ray diffractometer. The ideal selectivity of CO 2 /N 2 was enhanced significantly with the addition of a Cu‐MOF, and the values are higher in the Cu‐MOF/PEBAX MMM compared with that in a POZ based asymmetric MMM. Improvement in the CO 2 /N 2 selectivity of a Cu‐MOF/PEBAX MMM was achieved via facilitated transport by the CO 2 ‐selective Cu‐MOFs due to both their high adsorption selectivity of CO 2 over N 2 and the decreased crystallinity of PEBAX due to the presence of the Cu‐MOFs, which would provide a synergic effect on the CO 2 separation.