Tracers (14CO2) were used to measure self-diffusion in single pellets of type-A zeolite at -25 to 25C. Using a simple model for the pellet structure, it was possible to deduce the diffusivities for pore and crystal diffusion. For ordinary gas diffusion in the pores, the crystal diffusivities were of the order of 10-11cm2/s.

Diffusion of CO2 in Type 5A Molecular Sieve. R.W.H.Sargent, C.J.Whitford: Advances in Chemistry, 1971, 102, 155–63