  The intra-crystalline diffusion of normal alkanes in LTL and ZSM-12 zeolite
was experimentally studied via gravimetric measurements performed at different
temperatures. A periodic dependence of the diffusion coefficient on the number
of carbon atoms in alkane was detected, which is an experimental proof for
resonant diffusion. The present observations were described on the base of the
existing theory of the resonant diffusion and several important parameters of
the alkane-zeolite interaction and zeolite vibrations were obtained. In the
considered temperature region the diffusion coefficient follows the Arrhenius
law with periodic dependences of the pre-exponential factor and activation
energy on the number of carbon atoms in alkanes. A compensation effect of
simultaneous increases of the pre-exponential factor and the activation energy
was also established.
