Improving CO2 permeation and separation performance of CO2-philic polymer membrane by blending CO2 absorbents

To research effects of CO 2 absorption capacity and type of CO 2 absorbent on the CO 2 separation and free-volume properties of facilitated transport membranes, two types of CO 2 absorbents, namely monoethanolamine (MEA) and ionic liquids (ILs:[P 66614 ][Triz] and [P 66614 ][2-Op]), were adopted. The CO 2 absorption capacities of MEA, [P 66614 ][Triz] and [P 66614 ][2-Op] were about 0.561   mol CO 2 per mol, 0.95   mol CO 2 per mol and 1.60   mol CO 2 per mol, respectively. All mean free-volume hole radiuses of membranes decreased after blending CO 2 absorbents. After polymer membrane blended with two ILs, number of free-volume hole increased, resulting in modest increase of the fractional free volume. Both CO 2 permeability and selectivity increased after blending MEA and ILs. The increasing range of CO 2 permeability corresponded with CO 2 absorption capacity of CO 2 absorbents, and membrane blending with [P 66614 ][2-Op] showed the highest CO 2 permeability of 672.1 Barrers at 25   °C. Pebax/PEGDME membrane blending with MEA obtained the highest CO 2 /H 2 and CO 2 /CH 4 selectivity at 17.8 and 20.5, respectively.