Computer modeling study of interaction of acetonitrile with hydroxyl groups of HY zeolite

Adsorption of the acetonitrile molecules in HY zeolite was studied by a com bination of the molecular dynamics technique and the electronegativity equa lization method. A potential describing the hydrogen bonding between the ba sic CH3CN molecule and an acidic OH group of zeolite was parametrized on th e basis of experimental data. The results of the MD simulations show that t he interaction of the molecule with the OH groups strongly influences the e quilibrium geometry of the zeolite hydroxyls. The local environment of the OH groups in the HY lattice is calculated to play an important role for the structure and dynamics of the adsorption complexes of the acetonitrile wit h the zeolite hydroxyls, and for charge distribution in the adsorbed molecu les. Particularly, the calculations reveal that the acetonitrile is polariz ed to a larger extent in the H-bonded complex with OIH groups than upon the interaction with the O-2 hydroxyls and that the former OH groups are more strongly perturbed by the adsorption. Results of the study are expected to be used as a starting point for the modeling studies of the acetonitrile ad sorbed in H-forms of other zeolite structures.