このエントリーをはてなブックマークに追加
ID 20586
file
creator
Asaeda, Masashi
subject
silica membrane
molecular dynamics
gas permeation
micropore
NDC
Chemistry
abstract
The mechanisms involved in pressure driven gas permeation through a micropore on vitreous SiO2 membranes were examined molecular dynamics (MD) simulation. Virtual amorphous SiO2 membranes were prepared by the melt-quench method utilizing modified Born-Mayer-Huggins (BMH) pair potential and Stillinger-Weber (SW) three-body interactions. A dual control plane non-equilibrium MD (DCP-NEMD) technique was employed to simulate gas permeation phenomena under a constant upstream pressure, in which the permeating molecules were modeled as Lennard-Jones particles. The dependencies of the permeance of helium and CO2 molecules on temperature and pore size were examined. For cylindrical pores about 8 and 6 Å in diameter, the calculated temperature dependencies for the permeance of helium molecules were similar to the tendencies predicted by the normal Knudsen permeation mechanism, while in the case of CO2 permeation, a temperature dependency larger than helium and a significant deviation from the Knudsen mechanism were observed. The deviation was more obvious for the smaller 6 Å pore model. A simple gas permeation model that takes the effect of the pore wall potential field into consideration satisfactorily explained the permeation properties of CO2 in the high temperature region. The permeation mechanism was also examined from the viewpoint of the lateral potential and density distribution in a micropore. The values for the potential within micropores, predicted from the observed temperature dependencies of the gas permeation rate and using the simple gas permeation model, were in good agreement with the depth of the potential field resulting from the given potential parameters. The findings also indicate that the density (pressure) difference in a micropore between the pore entrance and exit, which could be enhanced by an attractive pore wall potential, might be the true driving force for permeation, particularly in the high temperature region.
journal title
Journal of Membrane Science
volume
Volume 293
issue
Issue 1-2
start page
81
end page
93
date of issued
2007-04-20
publisher
Elsevier B.V.
issn
0376-7388
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2007 Elsevier B.V.
relation url
department
Graduate School of Engineering