| Gas permeation properties of c-plane aligned hexagonal tungsten oxide membranes formed by multi-stage synthesis |
| Shintaro Wada1, Takeshi Hagio1,2, Hiroto Kunishi1, Jae-Hyeok Park2, Vanpaseuth Phouthavong1,3, Yuta Yamada1, Toshihiro Terao1,4, Xinling Li5, Supinya Nijpanich6, Ryoichi Ichino1,2 |
1Department of Chemical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603, Japan
2Institute of Materials Innovation, Institutes of Innovation for Future Society, Nagoya University, Nagoya, 464-8601, Japan
3Department of Chemistry, Faculty of Natural Sciences, National University of Laos, Vientiane Capital, Lao PDR
4Department of Materials Science and Engineering, School of Engineering, Nagoya University, Nagoya, 464-8603, Japan
5Key Laboratory for Power Machinery and Engineering of Ministry of Education, Shanghai Jiao Tong University, Shanghai, 200240, China
6Synchrotron Light Research Institute (Public Organization), Nakhon Ratchasima, 30000, Thailand |
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Received: January 23, 2023; Revised: June 16, 2023 Accepted: July 25, 2023. Published online: August 7, 2023. |
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| ABSTRACT |
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Crystalline microporous membranes are promising tools for gas separation because their molecular dimension pores allow us to accurately sieve molecules by size. Recently, microporous hexagonal WO3 was reported as a new potential membrane material and its membrane was found to enable separation of water from water/acetic acid mixtures. Pore size of hexagonal WO3 seemed to be also suitable for separation of small gasses; however, its gas permeation properties have not been reported. Additionally, densification of membranes by decreasing intercrystalline gaps are extremely important in gas separation. One effective method to densify polycrystalline membranes is to repeat membrane synthesis, namely multi-stage synthesis. Here, we attempt to prepare dense hexagonal WO3 membranes on porous tubular supports by multi-stage synthesis and examined their densification and gas permeation properties. Densification was confirmed by permeation of SF6 (gas molecule larger than pores of hexagonal WO3), and its potential for separating small gasses was considered from single gas permeation of He and He/SF6 permselectivity. The results indicated that the multi-stage synthesis is effective to densify the membranes and He/SF6 permselectivity reached 42.8 for three-stage synthesis under modified conditions, implying hexagonal WO3 is a potential membrane material for small gas separation. |
| Key words:
Hexagonal WO3 membrane · Multi-stage synthesis · Densifi cation · Crystal alignment · Gas permeation |
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