A highly selective polybenzimidazole-4,4'-(hexafluoroisopropylidene)bis(benzoic acid) membrane for high-temperature hydrogen separation

Abstract

A polymeric gas separation membrane utilizing polybenzimidazole based on 4,40-(hexafluoroisopropylidene)bis(benzoic acid) was prepared. The synthesized membrane has an effective permeating area of 8.3 cm2 and a thickness of 3062 mm. Gas permeation properties of the membrane were determined using H2, CO2 , CO, and N2 at temperatures ranging from 248C to 2008C. The PBI-HFA membranes not only exhibited excellent H2 permeability, but it also displayed superior gas separation performance particularly for H2/N2 and H2/CO2. The permeation parameters for both permeability and selectivity [PH2 and a(H2/N2); PH2 and a(H2/CO2)] obtained for the new material were found to be dependent on trans-membrane pressure difference as well as temperature, and were found to surpass those reported by Robeson in 2008.