We suggest that disordered framework aluminums and nonframework cations can
create a disordered electrostatic potential in zeolites that can lead to a
discrepancy between diffusivities measured by microscopic and macroscopic
experimental techniques. We calculate the value of the discrepancy and the
characteristic time scale at which it occurs for several ionic and polariza
ble species diffusing in zeolites. For ionic species, a discrepancy is almo
st inevitable. For polarizable species, a significant discrepancy may occur
in some zeolites only for long alkanes or large species such as benzene.