A study was made of the diffusion of single-component molecules in zeolites, characterized by an isotherm represented by a dual-site Langmuir model with a point of inflection. The systems investigated were n-hexane and n-heptane in MFI zeolite at 300K. Experiments conducted using the quasi-elastic neutron scattering technique demonstrated that this inflection had an impact on the loading dependence of the transport and corrected diffusion coefficients of these systems. A kinetic Monte Carlo study showed how the energy levels of the molecule adsorption sites in a zeolite affected the loading dependence of the diffusion coefficients of these molecules.

Kinetic Monte Carlo Modeling to Study Diffusion in Zeolite. Understanding the Impact of Dual Site Isotherm on the Loading Dependence of N-Hexane and N-Heptane Diffusivities in MFI Zeolite, as Revealed by QENS Experiments. N.Laloué, C.Laroche, H.Jobic, A.Méthivier: Oil and Gas Science and Technology, 2009, 64[6], 773-93