Mechanism of Diffusion in Zeolites

We have already explained the structure of zeolites and related materials (see Section 2.5.1). Diffusion in zeolites is a very important industrial problem and, consequently, it has been comprehensively 

Subsequently, it is possible to consider that the adsorbate-adsorbent interaction field inside these structures is characterized by the presence of sites of minimum potential energy for the interaction of adsorbed molecules with the zeolite framework and charge-compensating cations. A simple model of the zeolite-adsorbate system is that of the periodic array of interconnected adsorption sites, where molecular migration at adsorbed molecules through the array is assumed to proceed by thermally activated jumps from one site to an adjacent site, and can be envisaged as a sort of lattice-gas. 

In order to describe the adsorption and diffusion in the zeolites in the framework of a modified lattice-gas, which takes into account the crystalline structure of the zeolite, the interaction among adsorbed molecules and the possibility of a transition of adsorbed molecules among different adsorption sites in the same unit cell and different unit cells that follows the model description of molecular diffusion in zeolites were previously proposed [88,104], 

FIGURE 5.30 Schematic representation of the zeolite and a related material. 

The Physical Chemistry of Materials Energy and Environmental Applications 

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