Verification of the Maxwell–Stefan theory for diffusion of three-component mixtures in zeolites

Abstract

We develop the Maxwell–Stefan formulation for diffusion of multicomponent mixtures in zeolites and show that the mixture transport behaviour can be predicted on the basis of information of the pure component jump diffusivities at zero loading. The interaction between the diffusing, sorbed, species is taken into account by introduction of an interchange coefficients D – ij . The interchange coefficients D – ij encapsulate the correlations in the molecular jumps. A logarithmic-interpolation formula is suggested for estimating these interchange coefficients from the information on the pure component jump diffusivities. To verify the developed Maxwell–Stefan formulation, we have carried out kinetic Monte Carlo (KMC) simulations to calculate the transport diffusivities for a ternary mixture in silicalite. The KMC simulations confirm that the ternary mixture diffusion can be predicted with good accuracy with the Maxwell–Stefan theory.