title: Diffusion via space discretization method to study the concentration dependence of self-diffusivity under confinement.
abstract: The concentration dependence of self-diffusivity is investigated by means of a novel method, extending our previously developed second-order Markov process model to periodic media. Introducing the concept of minimum-crossing surface, we obtain a unique decomposition of the self-diffusion coefficient into two parameters with specific physical meanings. Two case studies showing a maximum in self-diffusivity as a function of concentration are investigated, along with two cases where such a maximum cannot be present. Subsequently, the method is applied to the large cavity pore network of the ITQ-1 (Mobil tWenty tWo, MWW) zeolite for methane (displaying a maximum in self-diffusivity) and carbon dioxide (no maximum), explaining the diffusivity trend on the basis of the evolution of the model parameters as a function of concentration.
authors.affiliation: School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, Zografou Campus, Athens 15780, Greece.
authors.forename: Marco
authors.initials: M
authors.lastname: Sant
authors.forename: George K
authors.initials: GK
authors.lastname: Papadopoulos
authors.forename: Doros N
authors.initials: DN
authors.lastname: Theodorou