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Effect of CVD parameters on hydrogen permeation properties in a nano-composite SiO 2-Al 2O 3 membrane

Amanipour, M ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.memsci.2012.09.007
  3. Publisher: 2012
  4. Abstract:
  5. Tubular ceramic membranes were synthesized by depositing a dense layer of silica-alumina on top of a multilayer substrate using co-current chemical vapor deposition (CVD) method. The multilayer substrate was prepared by coating with a series of bohemite sols with certain particle sizes. Cross-sectional and surface images obtained from high resolution FESEM showed that the intermediate layer had a thickness of about 1μm and the top selective layer was uniform and dense with a thickness of less than 100nm. Permeance tests, which were carried out with H 2, CO 2, N 2 and CH 4 at a high temperature range of 923-1073K, indicated that gas permeation took place via different mechanisms through different layers of the membranes. During the deposition time, permeance values were reduced and after 6h, H 2 permeation decreased from 5×10 -5molm -2s -1Pa -1 to 6.3×10 -7molm -2s -1Pa -1, but high selectivities of 105, 203 and 573 were obtained at 1073K for H 2 over CO 2, N 2 and CH 4, respectively. Hydrothermal stability tests at 1073K and in the presence of 30mol% steam showed that using 10mol% alumina precursor (ATSB) in the CVD method improved membrane stability, as after 96h of exposure to humidity, H 2 permeance flux of silica-alumina membrane with ATSB/TEOS molar ratio of 0.1 was 1.9 times more than that of a pure silica membrane
  6. Keywords:
  7. High temperature ; Hydrothermal stability ; Nano-composite membrane ; Alumina precursor ; Chemical vapor deposition methods ; CVD method ; Dense layer ; Deposition time ; Different mechanisms ; Gas permeation ; High resolution ; High selectivity ; High temperature range ; Hydrogen permeation ; Hydrothermal stabilities ; Intermediate layers ; Membrane stability ; Molar ratio ; Multilayer substrate ; Permeance ; Pure silica ; Selective layers ; Silica-alumina ; Surface image ; Tubular ceramic membranes ; Alumina ; Ceramic membranes ; Composite membranes ; Multilayers ; Nanocomposites ; Permeation ; Silica ; Sols ; Gas permeable membranes ; Aluminum derivative ; Aluminum oxide ; Aluminum tri sec butoxide ; Carbon dioxide ; Hydrogen ; Methane ; Nanocomposite ; Nitrogen ; Silicon dioxide ; Tetraethoxysilane ; Unclassified drug ; Chemical reaction ; Chemical vapor deposition ; Concentration response ; Gas permeability ; Parameters ; Particle size ; Priority journal ; Temperature sensitivity ; Thermostability ; Thickness
  8. Source: Journal of Membrane Science ; Volume 423-424 , 2012 , Pages 530-535 ; 03767388 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0376738812006722