On the consistency of zeolitic self-diffusion coefficients

Abstract

Using a simple model for molecular, translational motion in zeolites, following Ruthven and Doetsch, a relation between self-diffusion coefficients and Henry coefficients of adsorption isotherms is presented. It is shown that on the basis of this correlation preexponential factors of both Henry constants and self-diffusion coefficients can be estimated from the activation energy of self-diffusion. Self-diffusion measurements of alcanes in Na X zeolites, using NMR pulsed field gradient techniques, are in satisfactory agreement with this result.