Improvement in CO2/H2 separation by fabrication of poly(ether-b-amide6)/glycerol triacetate gel membranes

The purpose of this study is to investigate separation performance of poly(ether-b-amide6) (Pebax1657)/glycerol triacetate (GTA) gel membranes for CO2 removal from H2, N2 and CH4. GTA as a low molecular weight and highly CO2-phill compound was added to membrane structure at various weight fractions, 20%, 40%, 60% and 80% of Pebax, to fabricate a new high solubility selective membrane with improved performance. Permeation of pure gases was studied at different temperatures from 25 to 65 °C and pressures from 4 to 24 bar and ideal selectivities were calculated. Results indicated enhancement in permeation for all tested gases. For example, at a pressure of 4 bar and a temperature of 25 °C, membrane permeability with 80 wt% GTA for CO2, H2, N2 and CH4 increased by 8, 4, 13 and 18 times, respectively. Although CO2/H2 selectivity almost doubled, opposite results were observed for CO2/N2 and CO2/CH4 separations. However, the overall performance of membranes for CO2/N2 separation improved to the upper bound of Robeson graph, whereas CO2/CH4 separation did not improve. Morphology of membranes was characterized by SEM that showed remarkable changes. Also, DSC, FTIR spectroscopy and tensile analyses were applied to study thermal properties, peaks of functional groups and mechanical strength of fabricated membranes, respectively.