Preliminary Molecular Dynamics Simulation Studies of H-Y Zeolite in a Non-Rigid Zeolite Framework

Molecular dynamics (MD) simulation of non-rigid H-Y zeolite framework are performed at 298.15 and 5.0 K. Usual bond stretching, bond angle bending, torsional rotational, and non-bonded Lennard-Jones and electrostatic interactions are considered as intraframework interaction potentials. Calculated atomic parameters are in good agreement with the experiment, which indicates the successful reproduction of the framework structure and its motion. Both calculated bond lengths and bond angles are also in good agreement with the experiment except generally for a little longer bond lengths and a little smaller T-O-H bond angles. The calculated overall site occupation of H+ keeps the order O(2) > O(3) > O(4) > O(1) at 298.15 K, which is very different from the experimental prediction, O(1) > O(3) > O(2) at 5 K. Calculated IR spectra of the H-Y zeolite framework show that most of the main peaks of the O-H bonds are in the broad region 3700-5000 cm–1 and that the O-T stretching bands appeared in 0-2000 cm–1 and at 2700 cm–1 .