High-efficiency CO<sub>2</sub> separation using hybrid LDH-polymer membranes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34031381.
- Also identified by DOI 10.1038/s41467-021-23121-z and PMC identifier 8144556.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Membrane-based gas separation exhibits many advantages over other conventional techniques; however, the construction of membranes with simultaneous high selectivity and permeability remains a major challenge. Herein, (LDH/FAS)<sub>n</sub>-PDMS hybrid membranes, containing two-dimensional sub-nanometre channels were fabricated via self-assembly of unilamellar layered double hydroxide (LDH) nanosheets and formamidine sulfinic acid (FAS), followed by spray-coating with a poly(dimethylsiloxane) (PDMS) layer. A CO<sub>2</sub> transmission rate for (LDH/FAS)<sub>25</sub>-PDMS of 7748 GPU together with CO<sub>2</sub> selectivity factors (SF) for SF(CO<sub>2</sub>/H<sub>2</sub>), SF(CO<sub>2</sub>/N<sub>2</sub>) and SF(CO<sub>2</sub>/CH<sub>4</sub>) mixtures as high as 43, 86 and 62 respectively are observed. The CO<sub>2</sub> permselectivity outperforms most reported systems and is higher than the Robeson or Freeman upper bound limits. These (LDH/FAS)<sub>n</sub>-PDMS membranes are both thermally and mechanically robust maintaining their highly selective CO<sub>2</sub> separation performance during long-term operational testing. We believe this highly-efficient CO<sub>2</sub> separation performance is based on the synergy of enhanced solubility, diffusivity and chemical affinity for CO<sub>2</sub> in the sub-nanometre channels.