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

Membranes

S.Ted Oyama¹  Atsushi Takagaki²  Haruki Aono²  Ryuji Kikuchi²  Takashi Sugawara² 

[1] College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China;Department of Chemical Systems Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan;

关键词: silica-alumina membrane;    dimethyldimethoxysilane (dmdmos);    hydrothermal stability;    chemical vapor deposition;    gamma-alumina intermediate layers;    hydrogen helium separation;   

DOI  :  10.3390/membranes10030050

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown