Kinetic studies on sorption of n-hexane in vanadium substituted MFI type zeolites of various crystal morphologies

The MFI type materials isomorphously substituted with vanadium form crystals of two morphology 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 the crystals dimensions. An increase in the D-0 values with the vanadium content of the crystals has also been found, although it is not so well expressed as that with the dimensions. The increase in the D-0 values is from 1.1 x 10(-11) to 1.1 x 10(-10) m(2)/s and may be a consequence of an additional system of larger pores, which is not reflected in the adsorption isotherms due to common occurrence of these pores in all crystals. It is also possible that vanadium causes a superior structure ordering and a decrease in/weakening of diffusion barriers. (C) 2009 Elsevier Inc. All rights reserved.