Kinetic Monte Carlo Study of Binary Diffusion in MFI-Type Zeolite

1. Introduction Separation induced by kinetic effects has been investigated, using zeolites as a shape selective adsorbent [1]. The control of diffusion process, requiring a precise knowledge of self-, transport and corrected diffusivities (D self , D t and D C , respectively) of molecules inside the nanoporous material, is essential for the design of industrial applications. In the case of strongly-binding or tight-fitting guest-zeolite systems, residence times in adsorption sites are much longer than travel times between sites so that diffusion becomes a slow activated process. Diffusion can then be viewed as successive random jumps from an adsorption site to another by crossing free energy barriers. Combining Kinetic Monte Carlo (KMC) algorithm and lattice model is the most adapted technique to study diffusion at finite loadings of poorly connected systems [2]. By its flexibility, it allows to consider different type of sites and to account for their local environment. In this work, we report a study of the loading dependence of single-component diffusion of linear hexane (nC6) and of binary diffusion of nC6 and 2,2-dimethylbutane (22DMB) mixture in MFI-type zeolite at 300K, using a lattice model approach combined with KMC.