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Diffusion coefficient of hydrogen in a Pd‐Ag membrane: Effect of hydrogen solubility
Author(s) -
Jemaa N.,
Grandjean B. P. A.,
Kaliaguine S.
Publication year - 1995
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450730318
Subject(s) - hydrogen , solubility , diffusion , thermodynamics , permeation , chemistry , permeability (electromagnetism) , analytical chemistry (journal) , membrane , effective diffusion coefficient , materials science , chromatography , organic chemistry , medicine , biochemistry , physics , radiology , magnetic resonance imaging
The permeabilities of hydrogen through a Pd 75 ‐Ag 25 membrane have been measured at temperatures ranging from 423 to 573 K and under hydrogen pressure differences ranging from 69 to 256 kPa. From the available literature solubility data a neural network model has been developed in order to simulate the variation of the hydrogen content in the alloy as a function of pressure and temperature. Then, from steady state permeability measurements and calculated solubilities, the diffusion coefficients of hydrogen have been computed. At a given temperature, the diffusion coefficient has been found to decrease with the hydrogen content (0.1 ≤ n = H/M ≤ 0.37). A simple relation is then suggested to predict the variation of the diffusion coefficient on both temperature and hydrogen content. To account for the variation of the diffusion coefficient with n, the integration of Fick's law of diffusion has been performed numerically, resulting in non‐linear profile of hydrogen content through the membrane under steady state permeation.