Gas and Steam Permeation Properties of Cation-Exchanged ZSM-5 Membrane

NaZSM-5 powder and membranes were hydrothermally prepared. Their (1) steam (H<sub>2</sub>O) adsorption properties and (2) the permeation and separation of gas and H<sub>2</sub>O were evaluated before and after the cation exchange of Na<sup>+</sup> to K<sup>+...

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Main Authors: Yuichiro Hirota, Masaki Nakai, Kasumi Tani, Koya Sakane, Ayumi Ikeda, Yasuhisa Hasegawa, Sadao Araki
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Membranes
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Online Access:https://www.mdpi.com/2077-0375/15/3/70
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Summary:NaZSM-5 powder and membranes were hydrothermally prepared. Their (1) steam (H<sub>2</sub>O) adsorption properties and (2) the permeation and separation of gas and H<sub>2</sub>O were evaluated before and after the cation exchange of Na<sup>+</sup> to K<sup>+</sup> or Cs<sup>+</sup>. The quantity of adsorbed H<sub>2</sub>O decreased as the size of the cation increased, indicating that the micropore volume and effective pore size of ZSM-5 decreased after cation exchange. The H<sub>2</sub> and N<sub>2</sub> permeances after cation exchange were less than 5% of the values before cation exchange, indicating a significant reduction in gas permeability. In contrast, the reduction of the H<sub>2</sub>O permeance values of the ZSM-5 membranes before and after K<sup>+</sup> or Cs<sup>+</sup> exchange was lower than that of H<sub>2</sub>, resulting in improved H<sub>2</sub>O/H<sub>2</sub> separation performance. Compared with the NaZSM-5 membrane, the K<sup>+</sup>- or Cs<sup>+</sup>-exchanged ZSM-5 membranes exhibited superior H<sub>2</sub>O permselectivity, particularly at dilute H<sub>2</sub>O concentrations (<1 vol%).
ISSN:2077-0375