模板效应对β分子筛中Al原子分布的DFT理论计算研究(英文)  

Guest-Host Interactions of Tetraethylammonium Cations and Zeolite Framework for Distributions of Al in β Zeolite:a Density Functional Theory Calculation

作　　者：孙秀良[1] 黄崇品[1] 张傑[1] 

机构地区：[1]北京化工大学化工资源有效利用国家重点实验室,北京100029

出　　处：《无机化学学报》2009年第11期2053-2061,共9页Chinese Journal of Inorganic Chemistry

基　　金：国家重点基础研究发展规划(973)(No.2004CB217804);国家杰出青年科学基金(No.20625621)资助

摘　　要：基于量子化学中的密度泛函理论(DFT),通过β分子筛同模板剂四乙胺阳离子(TEA+)的主客体相互作用来讨论了模板剂分子对骨架Al的靶向作用。计算采用了密度泛函理论中的B3LYP方法在6-31G(d,p)基组上研究了β分子筛同TEA+主客体相互作用的几何结构、分子轨道、电荷分布以及9个不同骨架位置的相互作用能。研究结果表明:带正电荷的TEA+吸引β分子筛上Al原子形成的阴离子中心(Zeo-AlO4-),两者具有很好的匹配关系。通过主客体相互作用影响了Al原子在分子筛中的分布。骨架Al最有利于落位在β分子筛的T5和T6位,落位的稳定性顺序是GroupⅡ(T5,T6)>GroupⅢ(T7-T9)>GroupⅠ(T1-T4)。Guest/host interaction between the tetraethylammonium （TEA） cations molecule and the model cluster of zeolite, calculated with DFF method, was used to investigate the Al preferential location in β zeolite. The calculations were performed based on cluster model by using of B3LYP hydride functional and 6-31G （d, p） basis set. For these species the geometries, molecular orbitals, Mulliken atomic, and interaction energies were analyzed. According to the calculated results of orbital picture and charge distribution it was proposed that the template has a good fit with the host framework and the role of the template is shown to be crucial in order to elucidate the Al distributions. Therefore, the energeties during the synthesis process （zeolite＋template） that has to be considered, and in this scene the template accommodation within the microporous space acts not only as a structure director but also as a director of the Al distribution. Based on the distances and energies of the guest/host interaction about different T （T=Al） sites, it was predicated that the T5 and T6 sites are the most stable sites for the substitution of Al in the β zeolite framework; and the stability is in the order of Group Ⅱ （T5,T6） 〉 Group Ⅲ （T7-T9） 〉 Group Ⅰ （T1-T4）.

关 键 词：Β分子筛 Al落位 模板剂(TEA+) 相互作用 密度泛函理论 

分 类 号：O613.72[理学—无机化学] O614.31[理学—化学]