Mixed matrix membranes for gas separation by combination of silica MCM-41 and MOF NH2-MIL-53(Al) in glassy polymers

Two kinds of porous nanostructured materials, ordered mesoporous silica with MCM-41 type structure and metal-organic framework (MOF) NH2-MIL-53(Al), have been combined in the same mixed matrix membrane (MMM) with a commercial glassy polymer, polysulfone (PSF) Udel (R) or polyimide (PI) Matrimid (R), as the continuous phase. Characterization by XRD, SEM, TEM, glass transition temperature, Young's modulus and contact angle measurements suggested good filler dispersion and filler-polymer interaction. The application of the membranes to the H-2/CH4 mixture separation revealed optimum performances in terms of H-2/CH4 selectivity at 8/8 wt.% (67.3 at 19.5 Barrer of H-2 permeability) and 12/4wt.% (178 at 21.3 Barrer of H-2 permeability) silica/MOF loadings, respectively, for PSF and PI based MMMs. Furthermore, these MMMs resulted in superior gas separation performance than those with only one type of filler because of a synergy effect. Due to their complementary interaction, two types of particles in one membrane improved the dispersion of the filler phase. Simultaneously, MOF NH2-MIL-53(Al) due to its microporosity and flexibility enhanced the separation selectivity, while the mesoporous MCM-41 increased the permeability. (C) 2013 Elsevier Inc. All rights reserved.