Hollow silicalite-1 sphere-polymer mixed matrix membranes for gas separation

Mixed matrix membranes (MMMs) were prepared combining two different polymers (polysulfone Udel® and polyimide Matrimid®) and hollow silicalite-1 spheres (HZSs) with about 4 μm in diameter. These HZSs were obtained by hydrothermal synthesis from solid mesoporous silica spheres (seeded with silicalite-1 nanocrystals). With filler loadings varying between 0 and 16 wt.%, the MMMs were applied to the separation of H2/CH4, CO2/N2, and O2/N2 mixtures. For all the gas pairs tested, it was found that with a loading of 8 wt.% the MMMs performed better than those prepared with pure polymer, other different loadings and conventional silicalite-1 crystals of similar size to that of the HZS diameter. The highest selectivities obtained here for H2/CH4, CO2/N2, and O2/N2 mixtures were 180 (H2 permeability = 38.4 Barrer), 41.7 (CO2 permeability = 7.2 Barrer), and 8.5 (O2 permeability = 2.8 Barrer), respectively.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Mixed matrix membranes with hollow silicalite-1 spheres at a loading of 8 wt% performed better than those prepared with pure polymers. ▶ The highest H2/CH4, CO2/N2, and O2/N2 selectivities were 180 (H2 permeability = 38.4 Barrer), 41.7 (CO2 permeability = 7.2 Barrer), and 8.5 (O2 permeability = 2.8 Barrer), respectively. ▶ The good behavior of the hollow silicalite-1 spheres-mixed matrix membranes is attributed to the microporosity of the filler and to the bonding between the polymers and the external surface of hollow silicalite-1 spheres.