Effects of Pore Structure of Porous Glass on Gas Permeation

Abstract

Permeation characteristics of H₂, He, H₂, CO₂, CH₄ and C₂H₄ were studied by use of six kinds of porous glasses, the pore radii and volumes of which range from 10 to 12 nm and from 0.157 cm³/g to 0.817 cm³/g, respectively. The permeation rate of the porous glass, which has the pore volume of 0.157 cm³/g, could not been measured. The larger the pore volume, remarkably the higher value of the permeation rate. The permeatin rate of H₂ for the glass with the pore volume of 0.817 cm³/g was 1.88 x 10-7 m³(STP)/m². sPa(membrane thickness: 0.5 mm). This value was about 500 times as large as that reported by T. Kameyama et al. The permeation mechanism for the glass which has larger pore volume than 0.4 cm³/g was molecular flow, whereas surface flow was added to molecular flow for the glass with the pore volume smaller than 0.4 cm³/g. The path of the porous glass which had low porosity was very complicated.