Difference of diffusivities in zeolites measured by the non-steady-state and the steady-state methods

Diffusion coefficients reported for zeolites have ranged over a wide span of magnitude depending on methods of measurement. We have analyzed determinations made by various investigators and methods on a number of zeolites and guest molecules. When immobilization of a fraction of molecules is taken into account, the corrected diffusivities are consistent regardless of method and a unifying picture of diffusivities, valid for catalytic processes, is obtained.