Cellular automata for the mesoscopic simulation of adsorption and diffusion in zeolites

The thermodynamic and transport properties of molecules hosted in the confining framework of a microporous material like a zeolite are strongly affected by the geometrical restrictions imposed by the pore walls. In the ongoing effort to understand the phenomena induced by the effect of confinement, the use of numerical simulation methods at the atomistic scale like Molecular Dynamics turns out to be computationally very costly due to the large number of degrees of freedom involved. This motivated the search for a further simplified description of a host/guest system. In the present thesis a Cellular Automata approach has been used to embed the local, fully-reliable structure of cell thermodynamic models together with a kinetic scheme mimicking the competition mechanism in which guest molecules move between different locations in a zeolitic host. The resulting model is a Thermodynamic Partitioning Cellular Automaton (ThPCA), designed ad hoc to simulate both adsorption and transport properties of simple guest species in a LTA-type zeolitic host at the mesoscopic scale. Effects of correlation in the guests’ motion affecting their diffusivity under confinement are also modeled, thus making the ThPCA model an efficient and easy environment to perform coarse-grained simulations of adsorption and diffusion of simple molecules in microporous materials.