Abstract
This study, for the first time, demonstrates a new double-crosslinking approach to manipulate the microstructure and gas separation performance of PBI membranes for H2/CO2 separation at 150 °C. The PBI membranes were firstly blended with sulfonated polyphenylsulfone (sPPSU) as an ionic-crosslinker and then α,α′-dibromo-p-xylene (DBX) as a covalent crosslinker with the aid of thermal annealing. Experiments show that PBI and sPPSU interact on the molecular level. Different from conventional blends, the PBI/sPPSU blend membranes show both enhanced chemical resistance and greater fractional free volume (FFV) after annealing at elevated temperatures because of chain motion and ionic crosslinking. As a result, the blend membranes maintain their high permeability after annealing. The DBX addition further improves the chemical resistance and tightens the inter-chain spacing that results in membranes with a small FFV and pore size. Consequently, the DBX cross-linked blend membranes retain their high gas pair selectivity at high temperatures. The 50/50 PBI/sPPSU blend membrane crosslinked by 0.7 wt% DBX at 300 °C possesses the best separation performance surpassing the Robeson's upper bound. It has an impressively H2 permeability of 46.2 Barrer and a high H2/CO2 selectivity of 9.9 at 150 °C.
Original language | English |
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Pages (from-to) | 726-733 |
Number of pages | 8 |
Journal | Journal of membrane science |
Volume | 563 |
Early online date | 22 Jun 2018 |
DOIs | |
Publication status | Published - 1 Oct 2018 |
Externally published | Yes |
Keywords
- UT-Hybrid-D
- Double crosslinking
- Fractional free volume (FFV)
- Gas separation
- Homogeneous blend
- Hydrogen purification
- CO capture