A generalized model for the transport of gases in porous, non-porous, and leaky membranes. I. Application to single gases

Abstract

A theoretical framework for the transport of multi-component gases in membranes is formulated that includes simultaneous transport both through the pores and through the non-porous membrane phase. The model utilizes the extended dusty-gas model for describing te diffusion (ordinary, Knudsen, and surface diffusion) and flow of a multi-component gaseous mixture through the pores. In addition, the usual solution-diffusion model is adopted for describing the transport through the non-porous solid-phase. Some limiting forms of the generalized model are given. The model predictions are compared with experimental results for single gases reported in the literature for a variety of limiting situations involving one or more of these flux mechanisms. An experimental protocol is suggested for discerning the different mechanisms involved.