Impact of humidity on gas transport in polybenzimidazole membranes
Journal Article
·
· Journal of Membrane Science
- Univ. of California, Santa Barbara, CA (United States); OSTI
- Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
- Univ. of Texas, Austin, TX (United States)
Polybenzimidazoles (PBIs) are promising materials for high temperature H2/CO2 separation in applications such as steam reforming and pre-combustion carbon capture where significant amounts of water are often present. However, PBIs are hydrophilic, and the impact of humidity on PBI gas separation properties is relatively unexplored. Furthermore, opportunity exists to elucidate the interplay between plasticization, free volume, and gas transport in glassy polymer membranes such as PBIs. Here, this study investigates the effect of humidity on H2, O2, and CO2 permeabilities at 35 °C in a commercial PBI and two sulfone-containing PBIs. Water uptake significantly reduces PBI gas permeabilities at low humidities due to competitive sorption and antiplasticization. At high humidities, plasticization increases the permeabilities of larger gases in more hydrophilic PBIs. Effective fractional free volumes evaluated from gas permeation data and previously reported water sorption and dilation data suggest water plasticizes PBIs by increasing accessible free volume via enhanced molecular dynamics rather than by creating new free volume cavities.
- Research Organization:
- Univ. of Texas, Austin, TX (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-02ER15362
- OSTI ID:
- 1977435
- Alternate ID(s):
- OSTI ID: 1814546
- Journal Information:
- Journal of Membrane Science, Journal Name: Journal of Membrane Science Vol. 639; ISSN 0376-7388
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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