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arXiv · 2201.04986

Effective and efficient transport mechanism of CO$_2$ in subnano-porous crystalline membrane of syndiotactic polystyrene

Yoshinori Tamai
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Abstract

The gas permeation behavior in the single crystal of syndiotactic polystyrene (s-PS) S-I form was investigated in detail, in comparison to that in the s-PS $\varepsilon$ form. The S-I form exhibits high CO$_2$/N$_2$ and CO$_2$/CH$_4$ separation factors while preserving its high CO$_2$ permeability; a trade-off between selectivity and permeability was broken through.The mechanism of the effective and efficient transport of CO$_2$ in the S-I form was examined in relation to the cavity structure in the crystal. Because the CO$_2$ molecule is only fitted to the cavities in the S-I form, the solubility of CO$_2$ becomes high. In addition, tri-atomic molecules can more effectively diffuse in the S-I form compared with di-atomic molecules, as proved by the "long-gas" model. A novel design criterion for the CO$_2$ separation membranes is proposed based on the aspect of momentum transfer from polymer matrix to the penetrant.

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Yoshinori Tamai. 2022-01-13. Effective and efficient transport mechanism of CO$_2$ in subnano-porous crystalline membrane of syndiotactic polystyrene. https://doi.org/10.1016/j.memsci.2021.120202

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