Enhanced CO₂ transport through rod‐shaped Al₂O₃ nanoparticles for ionic liquid composite membranes

Highly selective composite membranes were prepared using 1‐butyl‐3‐methyl imidazolium tetrafluoroborate (BMIM⁺BF₄⁻) and rod‐shaped aluminum oxide onto polysulfone support. The BMIM⁺BF₄⁻/ rod‐shaped Al₂O₃ composite membrane with 50‐nm nanoparticles (NPs) showed a CO₂ permeance of 39.3 GPU and a CO₂/N₂ selectivity of 43.7. Rod‐like 50‐nm NPs in ionic liquids showed better performance than spherical 13‐nm NPs in membranes using the same weight ratio and same support. These results indicate that the shape of the NPs has a greater effect on CO₂ transport than the size of the NPs. The chemical and physical properties of this composite membrane were characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis. POLYM. COMPOS., 40:2954–2958, 2019. © 2018 Society of Plastics Engineers