Heterogeneous three-site lattice model for adsorption of aromatics in ZSM-5 zeolites: Temperature dependence of adsorption isotherms

The three-site lattice model of collective localized adsorption of aromatic s in ZSM-5 zeolites, presented in our previous publications, is extended by taking into account the effects of energetic heterogeneity of the sites of the same type. The appropriate theoretical equations are derived and used for simultaneous description of the experimental adsorption isotherms and h eats of adsorption of benzene and p-xylene in silicalite at 303 K. It is sh own that taking into account this additional level of heterogeneity leads t o a much better description of both the adsorption isotherms and the relate d heats of adsorption in these systems. The extended model also allows one to predict correctly the adsorption isotherms of benzene and p-xylene in si licalite at different temperatures using the parameters found at one temper ature.