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Stability of H_2-Permselective SiO_2 Films Formed by Chemical Vapor Deposition

Nam, S. W. and Gavalas, G. R. (1989) Stability of H_2-Permselective SiO_2 Films Formed by Chemical Vapor Deposition. In: Membrane reactor technology. AIChE symposium series. No.268. American Institute of Chemical Engineers , New York, NY, pp. 68-74. ISBN 9780816904648.

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Thin SiO_2 films were heat treated in different gas mixtures to determine their stability in functioning as high-temperature hydrogen permselective membranes. The films were formed within the walls of porous Vycor tubes by SiH_4 oxidation in an opposing reactants geometry. Film deposition was carried out at 450 °C in the presence and absence of water vapor. Immediately after formation, the films were highly selective to hydrogen permeation having a H_2:N_2 permeability ratio of about 3000 : 1. The films were subsequently heat treated at 450-700°C in dry N_2, dry O_2, N_2- H_2O, and O_2-H_2O mixtures. The permeation rates of H_2 and N_2 changed depending on the original conditions of film formation as well as on the heat treatment. Heating in dry N_2 reduced slowly the permeation rates of both H_2 and N_2. Heating in N_2-H_2O atmosphere led to a steeper decline of H_2 permeability. But the permeation rate of N_2 increased or decreased according to whether the film deposition had been carried out in the absence or presence of H_2O vapor, respectively. Thermal treatment in O_2 caused rapid decline of the permeation rates of H_2 and N_2 in films that were deposited under dry conditions. The decline was moderate in films deposited under wet conditions.

Item Type:Book Section
Gavalas, G. R.0000-0003-1468-6835
Additional Information:© 1989 American Institute of Chemical Engineers. This work was supported by the Caltech Consortium in Chemistry and Chemical Engineering.
Funding AgencyGrant Number
Caltech Consortium in Chemistry and Chemical EngineeringUNSPECIFIED
Series Name:AIChE symposium series
Issue or Number:268
Record Number:CaltechAUTHORS:20151105-153703909
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61910
Deposited By: Ruth Sustaita
Deposited On:06 Nov 2015 19:48
Last Modified:03 Oct 2019 09:13

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