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Open AccessArticle

Synthesis of Silica Membranes by Chemical Vapor Deposition Using a Dimethyldimethoxysilane Precursor

1
College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China
2
Department of Chemical Systems Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
3
Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
4
Present address: Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
*
Author to whom correspondence should be addressed.
Membranes 2020, 10(3), 50; https://doi.org/10.3390/membranes10030050
Received: 19 February 2020 / Revised: 11 March 2020 / Accepted: 15 March 2020 / Published: 22 March 2020
(This article belongs to the Special Issue Membranes: 10th Anniversary)
Silica-based membranes prepared by chemical vapor deposition of tetraethylorthosilicate (TEOS) on γ-alumina overlayers are known to be effective for hydrogen separation and are attractive for membrane reactor applications for hydrogen-producing reactions. In this study, the synthesis of the membranes was improved by simplifying the deposition of the intermediate γ-alumina layers and by using the precursor, dimethyldimethoxysilane (DMDMOS). In the placement of the γ-alumina layers, earlier work in our laboratory employed four to five dipping-calcining cycles of boehmite sol precursors to produce high H2 selectivities, but this took considerable time. In the present study, only two cycles were needed, even for a macro-porous support, through the use of finer boehmite precursor particle sizes. Using the simplified fabrication process, silica-alumina composite membranes with H2 permeance > 10−7 mol m−2 s−1 Pa−1 and H2/N2 selectivity >100 were successfully synthesized. In addition, the use of the silica precursor, DMDMOS, further improved the H2 permeance without compromising the H2/N2 selectivity. Pure DMDMOS membranes proved to be unstable against hydrothermal conditions, but the addition of aluminum tri-sec-butoxide (ATSB) improved the stability just like for conventional TEOS membranes. View Full-Text
Keywords: silica-alumina membrane; dimethyldimethoxysilane (DMDMOS); hydrothermal stability; chemical vapor deposition; gamma-alumina intermediate layers; hydrogen helium separation silica-alumina membrane; dimethyldimethoxysilane (DMDMOS); hydrothermal stability; chemical vapor deposition; gamma-alumina intermediate layers; hydrogen helium separation
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Oyama, S.T.; Aono, H.; Takagaki, A.; Sugawara, T.; Kikuchi, R. Synthesis of Silica Membranes by Chemical Vapor Deposition Using a Dimethyldimethoxysilane Precursor. Membranes 2020, 10, 50.

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