Wet Gas Separation Performances of Crosslinked Thermally Rearranged Poly(benzoxazole-co-imide) (XTR-PBOI) Hollow Fiber Membrane Modules

In practical applications for carbon capture at power plants, humidity in flue gas stream significantly affects gas separation performances, thus additional energy is required in comparison to dry condition. To access economical feasibility, understandings of change in CO₂ capture efficiency in presence of water vapor is crucial.

In this study, the effect of water vapor on gas permeation properties in crosslinked thermally rearranged poly(benzoxazole-co-imide) (XTR-PBOI) hollow fiber membrane modules was investigated [1]. For a clear analysis, their single and mixed-gas separation properties with water vapor were evaluated then compared to the case of crosslinked hydroxyl copolyimide (XHPI) hollow fiber membrane modules.

XTR-PBOI hollow fiber membrane modules presented enhancement in the permeate CO₂ flow rate, which is different from the hydrophilic XHPI membranes. It can be ascribed that hydrophobic XTR-PBOI modules are impervious to capillary condensation effect of water vapor in porous substructures. In addition, XTR-PBOI still retained enhanced CO₂ permeance and CO₂/N₂ separation factor even exposure to wet CO₂ composition cycle on the feed side from 14 vol.% to 100 vol.%. Note that the XTR-PBOI hollow fiber membrane modules even aged over 1 year without pretreatment exhibited stable CO₂ permeance of ~400 GPU and CO₂/N₂ permselectivity of over 20 under wet gas condition (less than 10 vol.%) for more than 250 h.

Keywords: Thermally Rearranged polybenzoxazoles (TR-PBOs); Gas Separation; Wet Gas System; Hollow Fiber Membrane Modules

References

1. J. H. Lee et al., J. Membr. Sci 539 412-420 (2017)