Combination of ordered mesoporous silica MCM-41 and layered titanosilicate JDF-L1 fillers for 6FDA-based copolyimide mixed matrix membranes

MCM-41 is an ordered mesoporous silica that can be prepared in a spherical shape (440 nm diameter), while JDF-L1 is a layered microporous titanosilicate with sheet-like growth habit (about 105 nm thickness) and a pore size of about 0.3 nm. JDF-L1 is a good material for H2 selective transport and MCM-41 spheres may improve permeability for most gases. These fillers have been used to cast mixed matrix membranes (MMMs) with copolyimide 6FDA-4MPD/6FDA-DABA as a continuous polymer matrix. JDF-L1 sheets with a preferential horizontal orientation provide H2 selectivity while improving the dispersion of MCM-41 particles in the MMMs. This was evidenced by statistical analysis of 30 cross-section backscattering SEM images in each analyzed membrane. Regarding H2/CH4 separation, MMMs containing 8 and 4 wt% of MCM-41 and JDF-L1, respectively, showed an optimum H2/CH4 selectivity value of 32.0 (with 440 Barrer of H2 permeability). Finally, this study demonstrates that MMM performance can be enhanced by combining highly selective inorganic sheets with highly permeable inorganic spheres.