A comparison on gas separation between PES (polyethersulfone)/MMT(Na-montmorillonite) and PES/TiO2 mixed matrix membranes

Abstract Polyethersulfone (PES)-based mixed matrix membranes (MMMs) with the incorporation of inorganic fillers of different shapes (lamellar Na-montmorillonite (MMT) clays and spherical TiO 2 nanoparticles) were prepared in this study, and the resulting MMMs were characterized by TGA, DSC, XRD, SEM, and TEM. It was found that inorganic filler agglomeration became more serious at higher-filler-content MMMs. In the case of PES/MMT MMMs, both the CO 2 and CH 4 permeabilities increased significantly with the increasing filler content and consequently the gas selectivity was greatly reduced. At high MMT loadings (⩾10 wt.%), Knudsen diffusion became the predominant gas transport mechanism. A different trend was achieved in the case of PES/TiO 2 MMMs. The CO 2 /CH 4 selectivity increased from 24.5 (pure PES membrane) to a maximum value of 38.5 at 4 wt.% TiO 2 MMM and then decreased with a further increase in TiO 2 content (e.g. 17.3 for 20 wt.%). The formation of interface voids and membrane defects in MMMs contributed to the high gas permeabilities and low gas selectivity.