MOF-containing mixed-matrix membranes for CO2/CH4 and CO2/N2 binary gas mixture separations

Both dense and asymmetric metal organic frameworks (MOFs) containing membranes were respectively prepared by solvent evaporation and phase inversion with Matrimid (R) as base polymer and three different MOFs: [Cu-3(BTC)(2)], ZIF-8 and MIL-53(AI) as filler. Incorporation of the fillers in the membranes resulted in an increase in thermal and mechanical stability of the membranes. However, the highest filler loadings (typically 40 wt%) deteriorated the properties of the membrane. An optimized priming protocol of the fillers before membrane preparation resulted in a homogeneous distribution of the MOFs, as confirmed with SEM. The possible presence of non-selective voids in the asymmetric membranes was overcome by coating a highly permeable silicone polymer layer on top of the MMMs. Dense membranes and asymmetric membranes for all the three studied MOFs showed improvement in CO2/CH4 and CO2/ N-2 selectivity and permeance as compared to the unfilled reference membrane. (C) 2011 Elsevier B.V. All rights reserved.