Permselectivity improvement of PEBAX® 2533 membrane by addition of glassy polymers (Matrimid® and polystyrene) for CO2/N2 separation

Abstract

AbstractTwo series of novel blend membranes based on poly(ether‐block‐amide) (PEBAX® 2533) and 5 and 10 wt% of two glassy polymers (Matrimid® and polystyrene [PS]) were prepared using a new mixed solvent with a low boiling point for CO2/N2 separation. Fourier‐transform infrared spectroscopy, field emission scanning electron microscopy, and X‐ray diffraction analyses were used to characterize the samples. A decrease in membrane crystallinity was observed by the addition of glassy polymers. The gas permeability measurements were performed to obtain CO2/N2 permselectivity of membranes. The maximum performance was found for the membrane with 5 wt% Matrimid content, for which CO2 permeability and CO2/N2 selectivity increased by 21% and 76%, respectively. Three permeation models were used to predict the CO2 permeability of blend membranes. The Maxwell model showed acceptable coincidence with the experimental data at 5 wt% content of the glassy polymer. For 10 wt% content of glassy polymer, the Lewis‐Neilson model showed the most accurate predictions for CO2 permeability. A method for quantitative comparison of membrane performance was also proposed by defining the geometric closeness to the Robson upper bound limit. Finally, it was found that an increase in the feed pressure improved the membrane performance at high pressures.