Elucidating the role of micropore-generating backbone motifs and amine functionality on membrane separation performance in complex mixtures

While significant advancements have been made in the synthesis of microporous polymers for gas separations in the last two decades, little is known regarding structure-property relationships under industrially relevant conditions involving highly condensable gases such as H2S. Recent work on the mixed-gas transport in an aminefunctionalized microporous PIM (PIM-NH2) has demonstrated benefits of simultaneous plasticization resistance and competitive sorption for increased permselectivity in binary CO2/CH4 mixtures. In this work, we elucidate the effects of analogous competitive sorption relationships through pure- and mixed-gas permeation in an aminefunctional microporous poly(aryl ether) (PAE-NH2) and provide comparisons with PIM-NH2 and the corresponding nitrile-functional counterparts, PAE-CN and PIM-1. In binary mixed-gas tests, PAE-NH2 show a 2.5- and 2.4-fold increase in CO2/CH4 and CO2/N2 mixed-gas permselectivities, respectively, compared to the pure-gas case. In 20/20/60 H2S/CO2/CH4 mixtures, amine-functionalized derivatives retain increases in CO2/CH4 selectivities compared to the nitrile-functional analogues. Additionally, PIM-NH2, PAE-CN, and PAE-NH2 have excellent plasticization resistance in 50/50 CO2/CH4 binary mixed-gas tests up to 26 atm.