中文摘要：

运用Gaussian 98程序包,采用密度泛函理论B3LYP方法,基于ZSM-5分子筛的8T模型,分别通过6-31G,6-31G（d）和6-311G（d,p）基组计算了ZSM-5分子筛中氮原子取代前后各O原子和各N原子的能量,从而得到各O原子与各N原子在骨架中的稳定性及其对氮化取代反应的影响.计算结果表明,N原子在骨架中的稳定性对氮取代反应的影响较大.ZSM-5分子筛晶体结构中与B酸位处于同一个四面体的O11位置,为氮原子的最佳取代位置,因此氮化后分子筛表面的B酸强度得到较大程度的减弱.

英文摘要：

Density Functional Theory study was performed to predict the nitrogen substitutional site in the framework of nitrogen-incorporated ZSM-5 zeolite.All the calculations were performed on 8T clusters of ZSM-5 by Gaussian 98 program at B3LYP/6-31G,B3LYP/6-31G（d）and B3LYP/6-311G（d,p）levels,respectively.The calculations on energies of O atoms and N atoms show that the stability of N atoms in the framework has bigger effect on the reaction of substitution than the stability of O atoms.The O11 site,which is in the same tetrahedron with Brnsted acid,is the most preferred site for nitrogen substitution in the framework of ZSM-5 zeolite.So the Br nsted acidity on the surface of zeolite after nitridation is decreased.