Influence of isotherm inflection on the diffusivities of C5-C8 linear alkanes in MFI zeolite

Molecular Dynamics (MD) simulations have been carried out to determine the Maxwell-Stefan (M-S) diffusivities Đi for linear alkanes with 5, 6, 7 and 8 carbon atoms in MFI zeolite at 433 K for a range of molecular loadings Θ. The dependence of the MS diffusivities Đi on the loading Θ was found to exhibit strong inflection behaviour; this is caused by the inflection in the corresponding sorption isotherm. The Đi-Θ dependence follows the trend suggested by Krishna et al. [R. Krishna, J.M. van Baten, D. Dubbeldam, J. Phys. Chem. B 108 (2004) 14820]. The inflection behaviour also extends to diffusivities in binary mixtures.