Tailoring sub-3.3 Å ultramicropores in advanced carbon molecular sieve membranes for blue hydrogen production

Carbon molecular sieve (CMS) membranes prepared by carbonization of polymers containing strongly size-sieving ultramicropores are attractive for high-temperature gas separations. However, polymers need to be carbonized at extremely high temperatures (900° to 1200°C) to achieve sub-3.3 Å ultramicropo...

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Published in:Science advances 2022-03, Vol.8 (10), p.eabl8160-eabl8160
Main Authors: Hu, Leiqing, Bui, Vinh T, Krishnamurthy, Ajay, Fan, Shouhong, Guo, Wenji, Pal, Sankhajit, Chen, Xiaoyi, Zhang, Gengyi, Ding, Yifu, Singh, Rajinder P, Lupion, Monica, Lin, Haiqing
Format: Article
Language:English
Subjects:
ENGINEERING
Materials Science
Physical and Materials Sciences
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Summary:Carbon molecular sieve (CMS) membranes prepared by carbonization of polymers containing strongly size-sieving ultramicropores are attractive for high-temperature gas separations. However, polymers need to be carbonized at extremely high temperatures (900° to 1200°C) to achieve sub-3.3 Å ultramicroporous channels for H /CO separation, which makes them brittle and impractical for industrial applications. Here, we demonstrate that polymers can be first doped with thermolabile cross-linkers before low-temperature carbonization to retain the polymer processability and achieve superior H /CO separation properties. Specifically, polybenzimidazole (PBI) is cross-linked with pyrophosphoric acid (PPA) via H bonding and proton transfer before carbonization at ≤600°C. The synergistic PPA doping and subsequent carbonization of PBI increase H permeability from 27 to 140 Barrer and H /CO selectivity from 15 to 58 at 150°C, superior to state-of-the-art polymeric materials and surpassing Robeson's upper bound. This study provides a facile and effective way to tailor subnanopore size and porosity in CMS membranes with desirable molecular sieving ability.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.abl8160