Synthesis of C-Plane Oriented Hexagonal Tungsten Oxide Membranes on Tubular Substrates and Their Acetic Acid/Water Separation Performances

Kunishi, Hiroto and Wada, Shintaro and Kamimoto, Yuki and Ichino, Ryoichi and Lin, Yan and Kong, Long and Li, Liang and Hagio, Takeshi (2021) Synthesis of C-Plane Oriented Hexagonal Tungsten Oxide Membranes on Tubular Substrates and Their Acetic Acid/Water Separation Performances. Membranes, 11 (1). p. 38. ISSN 2077-0375

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Abstract

Hexagonal tungsten oxide (h-WO3) membrane is a novel candidate for dehydration of acetic acid (CH3COOH)/water mixtures owing to its molecular sieving property and acidic resistance. Meanwhile, c-plane orientation is an important factor for h-WO3 membranes because the pores of h-WO3 run along its c-axis. However, so far, high c-plane orientation has not been successful on tubular substrates. Here, the effect of synthesis conditions of h-WO3 membranes on tubular substrates against c-plane orientation and CH3COOH/water separation performance are investigated. The h-WO3 membranes were prepared by hydrothermal synthesis from a precursor sol containing various amounts of sodium tungstate (Na2WO4) in the presence of tubular substrates with seeds embedded on their outside surface. The seeding method and the amount of Na2WO4 in the precursor sol significantly affected both crystal orientation and densification of the membrane. A precursor sol with appropriate amounts of Na2WO4 was essential to simultaneously satisfy high c-plane orientation and densification of the membrane while excess Na2WO4 drastically decreased the degree of c-plane orientation. A highly c-plane oriented h-WO3 membrane was successfully obtained under the optimized condition, which exhibited a maximum separation factor of 40.0 and a water permeance of 1.53 × 10−7 mol·m−2·s−1·Pa−1 in a 90:10 wt % CH3COOH/water mixture. The water permeance approximately doubled compared to the previous report, possibly owing to the significantly higher degree of c-plane orientation. Furthermore, it was found that its separation ability can be maintained while stored in 90:10 wt % CH3COOH/water mixture with pH < 0 for more than 500 h.

Item Type: Article
Uncontrolled Keywords: tubular substrate; c-plane orientation; hexagonal tungsten oxide membranes; seeding; dehydration; acetic acid/water mixtures
Subjects: STM Repository > Geological Science
Depositing User: Managing Editor
Date Deposited: 12 May 2023 05:26
Last Modified: 19 Mar 2024 03:58
URI: http://classical.goforpromo.com/id/eprint/1525

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