Intrinsic chemical tractability

Due to the successful implementation of polysulfone in hollow fibre membranes, this system has become the one to outperform. The intrinsic selectivity of polysulfone is high, with a CO2/CH4 separation factor of about 29, an H2/CH4 separation factor of about 54, and an H2 permeability of about 10 Barrer. A substantial amount of work has been done in trying to develop new polymers which are more permeable and more selective than polysulfone, while at the same time still tractable. The greatest success appears to have come from the polyimide class of polymers, though others are worthy of note. The work of Koros et al. showed the relationship between the chemical structures in a series of polyimides and their gas separation properties. The polyimides studied are shown in Fig. 11.3. 

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