钠离子在分子筛合成中的结构导向作用的分子模拟研究  

Molecular simulation studies on the structure directing effects of hydrate Na cation in the synthesis of microporous materials

作　　者：张宝吉[1] 任强[1] 

机构地区：[1]中国石油化工股份有限公司石油化工科学研究院,北京100083

出　　处：《计算机与应用化学》2009年第5期677-681,共5页Computers and Applied Chemistry

摘　　要：利用分子力学和分子动力学计算工具,对钠离子的各种水合结构及能量进行了分子力学和动力学的计算,以此研究水合钠离子所起的结构生成剂的作用。用Monte Carlo Docking方法对各种结构的水合钠离子在MFI分子筛微孔结构内的附着行为模拟计算。结果表明,配位数为偶数时水合阳离子的结构较为合理,这种合理性体现在当配位数为偶数时,Na_-^+nH_2O体系中金属离子的位置与氧原子的位置呈现对称结构,Na_-^+4H_2O和Na_-^+6H_2O是相对比较合适的结构;对于钠离子,配位数为4和6,当配位数大于6时,体系将自动转为6配位的情况;钠离子明显具有对周围的水分子结构进行重新排列的作用;钠离子的配位水分子数为4个或6个,而4配位结构是水合钠离子的主要存在方式之一;在MFI结构分子筛的合成中起模板剂作用的应该是Na_+^+4H_2O结构;计算结果对分子筛合成研究中水合离子的结构生成和结构破坏具有重要的意义。Molecular mechanics, molecular dynamics and Monte Carlo Docking tools were used to calculate the structure and energy of hydrate Na cation, and the docking of Na _^＋ nH2O clusters in MFI structure. It was found that the structure of hydrate Na cation was reasonable when the coordination number was even, it has symmetrical structure with the position of Na ＋ and O in Na _^＋ nH2O systems when the coordination number was even, Na _^＋ 4H2O and Na _^＋ 6H2O is located the rational structure. The coordination number was 4 and 6 for Na cation, the coordination number of system would turn into 6 when the coordination number more then 6. The Na cation has the role of realignment to the circumambient H： O of the Na cation. The coordination number of Na cation was 4 or 6, and one of main coordination structure for hydrate Na cation was 4 coordination structure. The structure of Na ＋ 4H2O has the effectiveness of template in MFI zeolite synthesis. The simulated data is very helpful to the study of structure-making and structure-breaking effectiveness of hydrate cation in zeolite synthesis.

关 键 词：金属阳离子 模板剂 分子模拟 

分 类 号：TQ015.9[化学工程] O6-39[理学—化学]