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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. http://resolver.caltech.edu/CaltechAUTHORS:20151105-153703909

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Abstract

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
ORCID:
AuthorORCID
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.
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Funding AgencyGrant Number
Caltech Consortium in Chemistry and Chemical EngineeringUNSPECIFIED
Record Number:CaltechAUTHORS:20151105-153703909
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151105-153703909
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61910
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Nov 2015 19:48
Last Modified:22 Sep 2017 17:58

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