Self-diffusivities in multicomponent mixtures in zeolites

Abstract

Using the Maxwell-Stefan formulation for diffusion in zeolites as a basis, we develop a general analytic expression for the self-diffusivity of a component in a multicomponent mixture. Correlation effects are accounted for by the introduction of particle-particle "exchange" coefficients. Various formulae for estimation of these exchange coefficients have been postulated. The developed procedure for estimation of the self-diffusivity is verified by comparison with kinetic Monte Carlo simulations for binary and ternary mixtures in MFI zeolite and in a square lattice. Additional verification of the analytic model is obtained using published molecular dynamics simulations and experimental data.