The n-hexane diffusion in ferrierite and silicalite-1, two molecular sieves belonging to the pentasil family, was studied using the zero-length column method. Large well-shaped crystals were synthesized. In silicalite-1, the effect of macroscopic twinning was verified by determining n-hexane diffusivities in the twinned and single silicalite-1 crystals. It was found that the so-called twinning had no effect upon the transport diffusivity of n-hexane in silicalite-1. This was in agreement with known structural data on twinned MFI frameworks. The n-hexane diffusion in ferrierite was four orders of magnitude smaller than that in silicalite-1 (table 20), and the activation energies were 32, 15 and 25kJ/mol for ferrierite, silicalite-T and silicalite-S, respectively. This was suggested to be a consequence of structural faulting.

Effect of Zeolite Structure and Morphology on Intracrystalline n-Hexane Diffusion in Pentasil Zeolites Studied by the Zero-Length Column Method. P.Voogd, H.Van Bekkum, D.Shavit, H.W.Kouwenhoven: Journal of the Chemical Society - Faraday Transactions, 1991, 87, 3575-80

Figure 10

Conductivity of Monocrystalline Ferrierite