The frequency-response method has been applied to compare the methane
diffusion processes in similar-size crystals of A-type zeolites contai
ning different exchangeable cations (K, Na, Ca). This has been done in
order to discriminate between inter- and intracrystalline diffusion.
The signal observed in NaA and NaCaA zeolites attributed to the intrac
rystalline diffusion is modified by surface barriers in the Linde crys
tals. The apparatus for diffusion measurements by the frequency-respon
se method is described.