The MFI type materials isomorphously substituted by vanadium formed crystals of two morphological types. Investigations of sorption kinetics for n-hexane indicated, for both morphologies, a non-typical increase in the value of corrected transport diffusion coefficient with crystal dimension. An increase in the D0 values with the vanadium content of the crystals was also found. The increase in the D0 value was from 1.1 x 10-11 to 1.1 x 10-10m2/s, and was proposed to be a consequence of an additional system of larger pores, which was not reflected in the adsorption isotherms due to the common occurrence of these pores in all crystals. It was also possible that vanadium caused superior structural ordering and a decrease-in or weakening of diffusion barriers.

Kinetic Studies on Sorption of n-Hexane in Vanadium Substituted MFI Type Zeolites of Various Crystal Morphologies. J.Kornatowski, J.Wloch: Microporous and Mesoporous Materials, 2009, 125[1-2], 17-22