Influence of Adsorption Kinetics on Gas Transfer through a Composite Membrane

A model has been proposed for gas transfer through a composite polymer membrane taking into account the influence of adsorption kinetics on the surfaces of a selective layer. An analytical expression has been obtained that describes the gas transfer with regard to a finite adsorption rate and is consistent with the corresponding experimental data on gas permeability. It has been shown that the effect of the finite adsorption rate on the gas transfer increases with a decrease in the thickness of the selective polymer layer and should be taken into account along with diffusion, when describing and analyzing the transfer through composite membranes with active layers thinner than 1 μm. It has been found that, at comparable rates of adsorption and diffusion, the permeability of a composite membrane is governed by the thickness of the selective layer and the surface porosity of a support, thus being in consistent with experimental data on gas transfer through composite membranes.