Jump to main content
Jump to site search

Issue 37, 2017
Previous Article Next Article

Tightening polybenzimidazole (PBI) nanostructure via chemical cross-linking for membrane H2/CO2 separation

Author affiliations

Abstract

Membranes that permeate H2 and reject CO2 at temperatures above 150 °C are of great interest for low-cost H2 purification and pre-combustion CO2 capture. One of the leading polymers for this separation is poly[2,2′-(m-phenylene)-5,5′-bisbenzimidazole] (PBI), which has good thermal stability and high H2/CO2 selectivity. This study, for the first time, demonstrates that H2/CO2 selectivity can be significantly enhanced by chemical cross-linking of PBI in solid state, in distinct contrast with the literature where cross-linking PBI in solutions decreased H2/CO2 selectivity. We prepared a series of cross-linked PBIs by immersing PBI thin films in terephthaloyl chloride solutions for varying times to achieve different degrees of cross-linking, and then systematically investigated the effect of cross-linking on physical properties including gel content, thermal stability, cross-linking density, fractional free volume (FFV) and inter-chain spacing. Gas sorption and pure- and mixed-gas permeation properties were determined at temperatures ranging from 35 to 200 °C. Cross-linking decreased CO2 sorption and significantly increased H2/CO2 selectivity with a slight decrease in H2 permeability. For example, after cross-linking of PBI, the H2/CO2 selectivity increased from 15 to 23 while the H2 permeability decreased from 45 to 39 Barrers at 200 °C. The performance of this cross-linked PBI surpasses the Robeson's upper bound estimated at 200 °C, indicating its promise for H2 purification and CO2 capture.

Graphical abstract: Tightening polybenzimidazole (PBI) nanostructure via chemical cross-linking for membrane H2/CO2 separation

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 May 2017, accepted on 04 Sep 2017 and first published on 05 Sep 2017


Article type: Paper
DOI: 10.1039/C7TA03874G
Citation: J. Mater. Chem. A, 2017,5, 19914-19923
  •   Request permissions

    Tightening polybenzimidazole (PBI) nanostructure via chemical cross-linking for membrane H2/CO2 separation

    L. Zhu, M. T. Swihart and H. Lin, J. Mater. Chem. A, 2017, 5, 19914
    DOI: 10.1039/C7TA03874G

Search articles by author

Spotlight

Advertisements