A molecular dynamics simulation of pressure-driven gas permeation in a micropore potential field on silica membranes

Journal of Membrane Science 293 巻 1-2 号 81-93 頁 2007-04-20 発行
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タイトル ( eng )
A molecular dynamics simulation of pressure-driven gas permeation in a micropore potential field on silica membranes
作成者
Asaeda Masashi
収録物名
Journal of Membrane Science
293
1-2
開始ページ 81
終了ページ 93
抄録
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.
著者キーワード
silica membrane
molecular dynamics
gas permeation
micropore
NDC分類
化学 [ 430 ]
言語
英語
資源タイプ 学術雑誌論文
出版者
Elsevier B.V.
発行日 2007-04-20
権利情報
Copyright (c) 2007 Elsevier B.V.
出版タイプ Author’s Original(十分な品質であるとして、著者から正式な査読に提出される版)
アクセス権 オープンアクセス
収録物識別子
[ISSN] 0376-7388
[DOI] 10.1016/j.memsci.2007.01.039
[NCID] AA00702477
[DOI] http://dx.doi.org/10.1016/j.memsci.2007.01.039