Inter-relation between self- and jump-diffusivities in zeolites

We have performed kinetic Monte Carlo simulations for diffusion of methane, perfluoromethane and 2-methylhexane in silicalite to study the inter-relations between self-, jump- and transport-diffusivities. Both the self- and jump-diffusivities were found to decrease with occupancy, or loading, within the zeolite matrix. Correlation effects cause the self-diffusivity to be lower in value than the jump-diffusivity. Using the Maxwell–Stefan theory for diffusion we derive a simple formula to relate the self- and jump-diffusivities.