An experimental study of combined gas phase and surface diffusion in porous glass

• Published in: Journal of membrane science Vol. 140; no. 2; pp. 165 - 184
• Main Authors: Tuchlenski, Axel, Uchytil, Petr, Seidel-Morgenstern, Andreas
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 18.03.1998; Elsevier
• Subjects: Chemistry; Colloidal state and disperse state; Diffusion in porous media; Dusty gas model; Exact sciences and technology; General and physical chemistry; Generalized Stefan–Maxwell equations; Membranes; Multicomponent interactions; Surface diffusion; Generalized Stefan–Maxwell equations; Surface diffusion; Diffusion in porous media; Dusty gas model; Multicomponent interactions; Gaseous diffusion; Porous membrane; Carbon dioxide; Adsorption isotherm; Porous glass; Nitrogen; Experimental study; Helium; Borosilicate glass; Mass transfer; Gaseous permeation; Tubular membrane; Vycor; Numerical simulation; Argon; Propane
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/S0376-7388(97)00270-6

The diffusion of inert and adsorbable gases and binary gas mixtures through porous glass has been studied experimentally. A modified Wicke–Kallenbach cell consisting of two gas compartments separated by a tubular mesoporous membrane was used. The scope of this paper is to quantify the contributions of gas phase and surface diffusion. Adopting the dusty gas model (DGM) for the description of gas phase mass transfer and a generalized Stefan–Maxwell (GSM) theory to quantify surface diffusion a combined transport model has been applied. The DGM was found to be well suited for the description of transport through the pores. Surface diffusion of adsorbable gases was analyzed experimentally for different loadings. The obtained Fickian surface diffusivities were found to be strongly concentration dependent. Multicomponent surface diffusion is mainly affected by adsorption equilibrium. Reliable predictions require an accurate knowledge of the competitive adsorption isotherms.