Study of self-diffusion of n-decane in NaX zeolite by the pulsed magnetic-field gradient NMR method

Translational mobility of n-decane molecules in a porous space of NaX zeoli te was studied within the wide ranges of diffusion times and temperatures. The dependence of the effective self-diffusion coefficient on diffusion tim e was established. Confined mobility of diffusant molecules inside the crys tallite was observed both for complete and partial filing of NaX pores with a liquid, when the adsorption barrier was absent at the interface between intra- and intercrystallite regions. It was suggested that obstacles are pr esent at the surface of NaX crystallites complicating the transfer of liqui d molecules from crystallite channels to intercrystallite space. True value of self-diffusion coefficient of rr-decane in the itracrystallite space of NaX was determined and its dependence on the concentration of liquid molec ules in zeolite channels was considered. A special attention was paid to th e study of molecular exchange between intra- and intercrystallite-confined liquids.