Dynamics in Complex Systems: Computer Simulation of the Migration of Ions and Neutrals in Zeolites

复杂系统动力学：沸石中离子和中性子迁移的计算机模拟

• 批准号: 0079215
• 负责人: Horia Metiu
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0079215&HistoricalAwards=false
• 关键词: Dynamics; Complex; Systems; Computer; Simulation

Horia Metiu of UC Santa Barbara is supported by the Theoretical and Computational Chemistry Program to perform computer simulations of forces acting on ions and water molecules inside a zeolite, and to use these results to explore how the species move through the zeolite. Also, proton transfer rates will be calculated, and complete kinetic descriptions and mechanisms will be evaluated. Rigorous methodology will be applied to small unit cell zeolites, with specific studies of sodium ion and water migration through sodalite and the reaction of ammonia with acidic chabazite. These processes are widely used in industrial applications, yet very little is known about them at an atomic level. All energy calculations will be performed with density functional theory, which considers the full unit cell of the solid. Rate constants of the important processes will be calculated using correlation function theory or transition state theory. The results will be used in a kinetic Monte Carlo program to simulate migration and kinetics over very long time and space scales. It is anticipated that the ability to calculate the properties of molecules inside zeolites will be improved to the point that this methodology will assist in the rational design of industrial processes. Zeolites are crystalline, porous solids that have the ability to absorb inside them a variety of molecules. This absorption is selective (certain molecules are preferred to others) and the selectivity can be used to separate various gases, to remove noxious products from a gas stream, or to replace undesirable ions with benign ones. Zeolites and their absorbed guest molecules interact strongly enough to induce unusual chemical reactions within the zeolite frame. This property has practical importance and is exploited to modify the hydrocarbon content of various products in the oil industry. The outcomes from this computer simulation project will improve the understanding of how fast molecules move inside a zeolite, what determines absorption selectivity, and what causes changes in the chemical behavior of the absorbed species.

加州大学圣巴巴拉分校的Horia Metiu得到了理论和计算化学项目的支持，对作用于沸石内离子和水分子的力进行计算机模拟，并利用这些结果来探索物质如何通过沸石移动。 此外，质子转移率将被计算，完整的动力学描述和机制将被评估。 将对小晶胞沸石采用严格的方法，具体研究钠离子和水通过方钠石的迁移以及氨与酸性菱沸石的反应。 这些过程广泛用于工业应用，但在原子水平上对它们知之甚少。 所有的能量计算都将采用密度泛函理论进行，该理论考虑了固体的完整晶胞。 重要过程的速率常数将使用相关函数理论或过渡态理论计算。 其结果将用于一个动态蒙特卡罗程序，以模拟在很长的时间和空间尺度上的迁移和动力学。 预计计算沸石内分子性质的能力将提高到这种方法将有助于工业过程的合理设计的程度。 沸石是一种晶体状的多孔固体，能够吸收各种分子。 这种吸收是选择性的（某些分子比其他分子更优选），这种选择性可用于分离各种气体，从气流中去除有毒产物，或用良性离子取代不需要的离子。 沸石和它们吸附的客体分子相互作用强烈，足以在沸石框架内引发不寻常的化学反应。 该性质具有实际重要性，并被用于改变石油工业中各种产品的烃含量。 这个计算机模拟项目的结果将提高人们对分子在沸石内移动的速度、决定吸收选择性的因素以及导致被吸收物质化学行为变化的因素的了解。