The diffusion of benzene in high-silica ZSM5 was studied for various coverages using pulsed-field gradient nuclear magnetic resonance and quasi-elastic neutron scattering. The former technique probed inter- and intra-crystalline diffusion over the ms time-scale, yielding intra coefficients of the order of 10−10m2/s and inter coefficients in the range of 10−7 to 10−9m2/s with increasing coverage. This suggested the existence of a so-called viscous liquid-like environment within the zeolite, with faster diffusion between crystallites. The quasi-elastic technique probed intra-crystalline diffusion at the ns time-scale, giving results in the range of 10−10 to 10−9m2/s at high coverages. A jump activation energy of 5.0kJ/mol was estimated for 213 to 343K. The Diffusion of Benzene in High Silica Zeolite ZSM5 Studied by PFGNMR and QUENS. M.Morgan, T.Cosgrove, R.Richardson: Colloids and Surfaces, 1989, 36[2], 209–19

Table 60

Parameters for Diffusion in H-ZSM-5