Abstract: Density functional theory was used to predict the preferred oxygen site substituted by a nitrogen atom in the nitridation of the ZSM-5 zeolite. Calculations were performed on an 8T cluster of ZSM-5 by the Gaussian 98 program at the B3LYP/6-311G(d,p)level. The calculated results showed that the most preferred oxygen sites substituted by nitrogen are O11and O21sites. Because the O11atom located at the Bronsted acid site is one of the most preferred sites for nitrogen substitution, nitridation can decrease the strength of Bronsted acid on the surface of the ZSM-5 zeolite.

Key words: density functional theory, ZSM-5 zeolite, nitridation, substitution