Owing to their high CO2 flux, membranes made from thermally rearranged (TR) polymers are under active investigation for several applications involving CO2 removal.  TR polymers are thermally stable up to 300 �C and are resistant to hydrolysis.  For these reasons, they are strong candidates for CO2 capture from flue gas sources.  Because water vapor is a major constituent of flue gas, a thorough understanding its influence on gas transport in these materials is important.In this work, results of permeation experiments are presented for mixtures of CO2, N2, and water vapor in TR polymers derived from 3,3'-dihydroxy-4,4'-diamino-biphenyl (HAB) and 2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA).  HAB-6FDA polyimide films were converted to polybenzoxazloe (PBO) by heating to 350-450 �C under flowing nitrogen.  Permeation tests were conducted using converted PBO films for pure CO2, N2, and H2O, for binary CO2/N2 mixtures, and for ternary CO2/N2/H2O mixtures.  It was found that the permeabilities of both CO2 and N2 in these PBOs are depressed strongly in the presence of water vapor.  For example, for a 50% CO2/N2 mixture at 10 bar and 35 �C in a PBO film, both CO2 and N2 permeabilities decreased by more than half at 50% relative humidity from their values for dry gas; CO2/N2 selectivity increased by about 10% for the wet gas versus the dry gas.  These experimental results are discussed within the framework of the dual-mode sorption and permeation model.

Influence of water vapor on mixed-gas permeation of CO<sub>2</sub>/N<sub>2</sub> in thermally rearranged (TR) polymers

248th National Meeting (2014)

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Influence of water vapor on mixed-gas permeation of CO2/N2 in thermally rearranged (TR) polymers

Influence of water vapor on mixed-gas permeation of CO₂/N₂ in thermally rearranged (TR) polymers