Intracrystalline Diffusion in Zeolites Studied by Neutron Scattering Techniques

摘要

Neutron scattering techniques can be used to study the different motions of molecules adsorbed in zeolites: vibrations,rotations and translation.Using combined instruments,it is now possible to measure diffusivities ranging from 10~(-7) to 10~(-14) m~2s~(-1).Furthermore,incoherent scattering,using hydrogenated molecules,allows to determine the self-diffusivity;while coherent scattering,studying deuterated molecules,gives access to the transport diffusivity.Several applications of the neutron techniques are described in this review.They are illustrated by the case study of xylenes in X-type zeolites.Other examples are related to alkanes in MFI-type zeolites,n-alkanes in 5A zeolite,and water in X and A-type zeolites.