Adsorption and Diffusion of Benzene in ITQ-1 Type Zeolite: Grand Canonical Monte Carlo and Molecular Dynamics Simulation Study

The methods of grand canonical Monte Carlo (GCMC) simulation and molecular dynamics (MD) are used for investigating the adsorption and diffusion of benzene in ITQ-1 zeolite. First, the adsorption energies and preferred adsorption sites of benzene in ITQ-1 are determined by using GCMC simulations. The obtained mass clouds show that the diffusion and the mobility of benzene mainly happen in 12-MR supercages where the preferred adsorption sites of benzene can be divided to three separate adsorption sites. Then MD simulations are employed to analyze the dynamic diffusion processes in zeolite. The calculated diffusion coefficients are compared with the results of Sastre et al. (Sastre, G.; Catlow, C.; Corma, A. J. Phys. Chem. 1999, 103, 5187). From the trajectories followed by the benzene molecules, it can be seen that the guest molecules do not diffuse in both channel systems, and only intracage mobility is seen in the supercage voids. Moreover, the two benzene molecules near the S2 and S3 sites prefer to adopt a synergistic state, indicating that the benzene molecules at the S2 and S3 sites can produce relatively strong aromatic stacking interactions. In the present study, two sets of potential parameters are compared. For the molecules studied, these two force fields furnish similar and comparable results, although the obtained interaction energy and adsorption isotherms exhibit some differences. 1