Wet CO2/N2 permeation through a crosslinked thermally rearranged poly (benzoxazole-co-imide) (XTR-PBOI) hollow fiber membrane module for CO2 capture

Recently developed crosslinked-thermally rearranged (XTR) polymeric membranes, which show enhanced gas separation, are applicable for CO2 separation from post-combustion gases. Moreover, the resulting thermally rearranged polybenzoxazole (TR-PBO) structure that is thermally induced from hydroxyl-polyimides (HPI) provides high thermal and chemical resistance, which is favorable for gas separation applications containing condensable gases such as water vapor. Herein, the influence of water vapor on the CO2 capture efficiency was evaluated using XTR poly(benzoxazole-co-imide) (XTR-PBOI) hollow fiber membrane modules which were compared with crosslinked HPI (XHPI) in mixture gas and single gases for CO2 and N-2. The results revealed that the permeate CO2 flow rate in the hydrophobic XTR-PBOI module showed enhanced separation performance, whereas the flow rate severely decreased in the relatively hydrophilic XHPI module, reflecting more significant capillary condensation effect in the XHPI membranes. Both membrane modules showed excellent plasticization resistance, and the XTR-PBOI hollow fiber membrane module presented reasonable long-term stability over 240 h.