Synthesis of gas and vapor molecular sieving silica membranes and analysis of pore size and connectivity

Balagopal N. Nair, K. Keizer, H. Suematsu, Y. Suma, N. Kaneko, S. Ono, T. Okubo, S.I. Nakao

Research output: Contribution to journalArticleAcademicpeer-review

30 Citations (Scopus)

Abstract

Pervaporation and gas permeation properties of microporous silica membranes made by a sol−gel method are discussed. Defect free molecular sieving membranes are prepared by a dip coating process. The molecular sieving performance was measured and controlled based on gas permeation behavior of the membranes. The apparent activation energy for helium permeation and He/N2 perm-selectivity values were used as the parameters for optimization of the membrane performance. The membranes with very high activation energy for He diffusion were used for pervaporation studies with a methanol/MTBE mixture at 323 K. Separation factor values as high as 260 were measured at a total liquid flux of 0.3 kg/m2 hr. Sorption studies performed on corresponding silica gels revealed a separation mechanism based on diffusion of vapor molecules. Permeation of the vapor molecules through the micropores followed an activated diffusion mechanism. The gas permeation data could provide an understanding of the pore size distribution of the membrane, and the vapor sorption and diffusion data on the size and connectivity of the membrane pores.
Original languageEnglish
Pages (from-to)4558-4562
Number of pages5
JournalLangmuir
Volume16
Issue number10
DOIs
Publication statusPublished - 2000

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