The nmr pulsed field gradient technique is applied to study molecular self-diffusion in zeolitic adsorbate—adsorbent systems. Depending on the zeolite type and on the nature of the adsorbate—adsorbent interaction, the concentration dependence of the self-diffusion coefficients reveals considerable differences. Furthermore, intracrystalline molecular transport may be significantly influenced by the co-adsorption of a second molecular species. Supported by additional nuclear magnetic relaxation and sorption rate measurements microdynamic models for the observed diffusion behaviour are established.
Concentration dependence of intracrystalline self-diffusion in zeolites