Hybrid H 2-Selective Silica Membranes Prepared by Chemical Vapor Deposition

Yunfeng Gu, Bita Vaezian, Sheima J. Khatib, S. Ted Oyama, Zhenxing Wang, Luke Achenie

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Hybrid organic-inorganic H 2-selective membranes consisting of single-layer or dual-layers of silica incorporating aromatic groups are deposited on a porous alumina support by chemical vapor deposition (CVD) in an inert atmosphere at high temperature. The single-layer silica membranes, which are made by the simultaneous decomposition of phenyltriethoxysilane (PTES) and tetraethylorthosilicate (TEOS), have good hydrothermal stability at high temperature and a high permeance for hydrogen in the order of 10 -7 mol m -2 s -1 Pa -1 at 873 K, while preventing the passage of other larger molecular gases such as CH 4 and CO 2. The dual-layer silica membranes, which are obtained from the sequential decomposition of PTES and TEOS, exhibit an extremely high permeance for hydrogen of 3.6 × 10 -6 mol m -2 s -1 Pa -1 at 873 K with a permselectivity of hydrogen over methane of 30. A normalized Knudsen based permeance method is applied to measure the pore size of PTES-derived silica membrane on the dual-layer silica membrane before treatment with TEOS. The method indicates that the pore size of the silica network is approximately in the range of 0.50-0.85 nm, which is higher than the characteristic length of pure silica membranes of 0.3 nm, accounting for the high permeance of the hybrid membranes.

Original languageEnglish
Pages (from-to)1698-1708
Number of pages11
JournalSeparation Science and Technology (Philadelphia)
Volume47
Issue number12
DOIs
StatePublished - Jul 2012

Keywords

  • CVD
  • gas separation
  • hybrid membrane
  • hydrophobic membranes
  • silica membrane

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