NH2-MIL-53(Al) and NH2-MIL-101(Al) in sulfur-containing copolyimide mixed matrix membranes for gas separation

Amino functionalized MOFs (NH2-MIL-53(Al) or NH2-MIL-101(Al)) were used as dispersed phase in the fabrication of mixed matrix membranes (MMMs) with a polymer matrix of sulfur-containing copolyimides (6FDA:DSDA/4MPD:4,4'-SDA 1:1 (polymer P1) or 6FDA/4MPD:4,4'-SDA 1:1 (polymer P2)). The gas separation properties of the MMMs obtained were tested for permeation of H-2, CH4 and CO2. Membranes comprising polymer P1 showed better interaction with the fillers used than those with polymer P2, and therefore better separation properties, especially for NH2-MIL-101(Al). Upon NH2-MIL-101(Al) loading the performance of pure polymer was improved approaching the Robeson 1991 H-2/CH4 and CO2/CH4 upper bound limits with high permeabilities, e.g. 114, 71 and 1.7 Barrer for H-2, CO2 and CH4, respectively, using 10 wt.% NH2-MIL-101(Al)@P1. These improvements are related to the pore size of the filler, the flexibility and functional groups of sulfone-containing DSDA, and polymer rigidification. (c) 2013 Elsevier B.V. All rights reserved.