A novel high-performance facilitated transport membrane by simultaneously using semi-mobile and fixed carriers for CO2/N2 separation

Abstract

In this study, poly (ether-block-amide) (Pebax) facilitated transport membranes (FTMs) containing aniline, and ionic liquid (IL) modified alumina (M-Al) particles were prepared. Aniline molecules acted as semi-mobile carriers and IL-modified particles as fixed carriers for CO2 molecules in these membranes. Different amounts of M-Al particles were added to the Pebax/aniline (50 wt%) membrane, and a facilitated transport membrane containing 5 wt% M-Al particles was obtained as the optimal membrane. For Pebax/aniline (50 wt%)/M-Al (5 wt%) membrane, CO2 permeability was 167 barrer, and CO2/N2 selectivity was 123 increased by 94% and 168% compared to pure Pebax membrane, respectively. The CO2 separation performance of the prepared FTMs was also evaluated in the humidified state. The results showed that in the presence of water, the amino groups in the structure of aniline and IL performed better and improved the facilitated transport mechanism. Therefore, for all FTMs, CO2 permeability significantly increased in the humidified state so that CO2 permeability and CO2/N2 selectivity reached 406 barrer and 123, respectively, for optimal membrane. The molecular simulation was used to study details of the motion of aniline molecules in the polymeric matrix. The simulation and experimental results confirmed each other and showed that the presence of aniline prevents the hopping mechanism from stopping even at low concentrations of particles as fixed carriers and creates a combined hopping-vehicle mechanism in the membrane structure that results in excellent performance membranes.