Kinetic Monte Carlo simulations of transport diffusivities of binary mixtures in zeolites

We develop the Maxwell-Stefan formulation for diffusion of binary mixtures in zeolites, and show that the mixture transport behaviour can be predicted on the basis of information on the pure component jump diffusivities at zero loading. The interaction between the diffusing, sorbed, species is taken into account by the introduction of an interchange coefficient D-ij, which is estimated using a logarithmic interpolation formula. To verify the developed Maxwell-Stefan formulation, we have carried out kinetic Monte Carlo (KMC) simulations to calculate the transport diffusivities for binary mixtures in silicalite and also on a square lattice. The KMC simulations confirm that the binary mixture diffusion can be predicted with very good accuracy. The interchange coefficient D-ij encapsulates the correlations in the molecular jumps.