In this study, the goal is to incorporate superior features of the Pebax 1657 copolymer, such as high mechanical resistance and exceptional gas permeability especially for polar gases, with the affinity of the 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid to CO2 gas, which results in increasing the permselectivity of the membranes for CO2/light gases separation. Generally, the CO2 solubility in ILs increases with pressure increment, and temperature decrement. Therefore, gas permeation results of prepared membranes were obtained at temperature of 35 C and feed pressure range 2–10 bar. SEM, ATR and DSC analysis were carried out on different compositions of membranes and the results showed that adding the IL to the polymer make membranes more amorphous and less crystalline which lead to increase permeability for all tested gases. In addition, due to the high affinity of CO2 in both polymer and IL, both CO2 permeability and selectivity increased simultaneously with increasing IL content. This is confirmed by gas permeation results, where at 35 C and 10 bar, the CO2 permeability increased from 110 Barrer for neat Pebax to 190 Barrer in the blended membrane containing 50 wt.% IL (about 73%). The related CO2/CH4 and CO2/N2 selectivities were increased from 20.8 to 24.4 (about 17%) and from 78.6 to 105.6 (about 34%), respectively. Thus, these types of membranes are promising to be utilized in gas separation processes in industries for CO2 separation in order to postpone the global warming, which is nowadays the biggest threat to the universe.
