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Unprecedented size-sieving ability in polybenzimidazole doped with polyprotic acids for membrane H2/CO2 separation

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Abstract

Polymers with efficient and tight chain-packing and thus strong size-sieving ability are of great interest for H2/CO2 separation. Herein, we demonstrate a new approach to manipulating polymer structure by acid doping, leading to superior H2/CO2 separation performance. We have doped polybenzimidazole (PBI) with polyprotic acids, specifically H3PO4 and H2SO4. These acids cross-link PBI chains and drastically decrease free volume, improving the material's H2/CO2 selectivity to far surpass the Robeson's 2008 upper bound for membrane performance. For example, PBI doped with H3PO4 at a molar ratio of 1 : 1 exhibits an unprecedented H2/CO2 selectivity of 140 at 150 °C, which exceeds that of previously known polymeric materials and is superior or comparable to that of state-of-the-art 2D materials with sharp size separation, such as graphene oxide, MoS2, and metal–organic frameworks. This facile approach to enhancing polymer chain-packing efficiency opens up a new avenue for designing strong size-sieving polymers for membrane gas separations.

Graphical abstract: Unprecedented size-sieving ability in polybenzimidazole doped with polyprotic acids for membrane H2/CO2 separation

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Publication details

The article was received on 06 Oct 2017, accepted on 12 Dec 2017 and first published on 12 Dec 2017


Article type: Communication
DOI: 10.1039/C7EE02865B
Citation: Energy Environ. Sci., 2018, Advance Article
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    Unprecedented size-sieving ability in polybenzimidazole doped with polyprotic acids for membrane H2/CO2 separation

    L. Zhu, M. T. Swihart and H. Lin, Energy Environ. Sci., 2018, Advance Article , DOI: 10.1039/C7EE02865B

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