Permeation Flux in Zeolite Membranes

Transport in zeolites depends on the adsorption properties and is an activated phenomenon. For the surface diffusion mechanism, the diffusion flux can be expressed as [8] 

At intermediate temperatures (298-350K), the adsorption can be described by a Langmuir isotherm  

Integration of Eq. (3.1) over the membrane thickness 5 gives the permeation flux  

When the surface diffusivity (D ) is independent of occupation rate, its temperature dependence can be described by the Arrhenius equation  

This indicates that the permeation flux is dependent on the difference between the adsorption heat and the diffusion activation energy. 

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