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

Abstract

Facilitated mixed-matrix membranes (MMMs) containing Cu-metal organic frameworks (Cu-MOFs) with high CO2 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((R))MH 1657) block copolymer were chosen as the polymeric matrix and the effect of the matrix on CO2 separation for MMMs containing Cu-MOFs was investigated. The interaction of CO2 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 CO2 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 CO2/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 CO2/N-2 selectivity of a Cu-MOF/PEBAX MMM was achieved via facilitated transport by the CO2-selective Cu-MOFs due to both their high adsorption selectivity of CO2 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 CO2 separation. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42853.