CAREER: Atomically Detailed Modeling of Transport through Zeolite

摘要提案编号：CTS-9983647主要研究者：大卫S. Sholl机构：卡内基梅隆大学职业：沸石分子筛是一种固体晶体材料，由有序的纳米级孔网络渗透而成。这些孔与许多小分子的大小大致相同。因为吸附在沸石孔内的分子总是与孔壁紧密接触，所以各种化学物质的扩散速率和吸附能可以强烈地取决于物质的尺寸、形状和功能性。这些事实在沸石的择形催化和基于吸附的分离的应用中长期被利用。近年来，在由沸石晶体制成的超薄膜的可靠合成方面取得了显着进展。这些膜的持续发展的一个重要挑战是需要精确的理论模型，其性能。该项目将侧重于开发分子通过沸石膜传输的分层模型，该模型将详细的原子尺度模拟与宏观非平衡热力学理论相结合。这一过程的一个重要部分将是本研究的理论预测与实验合作者获得的实验结果之间的一系列直接比较。沸石膜具有许多吸引人的性质。从宏观角度来看，它们具有优异的热稳定性、机械稳定性和化学稳定性。这些性质允许沸石膜在对于传统膜材料如聚合物来说太苛刻的条件下使用。在微观上，沸石的原子有序的孔结构意味着沸石膜原则上甚至对于具有非常相似形状和尺寸的分子的混合物也可以具有极高的选择性。通过开发明确说明沸石孔的原子级结构的理论模型，该项目将开发一个框架，用于计算筛选沸石结构库，以选择优化所需化学分离的通量和选择性的膜材料。在短期内，这项工作将澄清控制分子通过沸石膜传输的基本微观过程，并为现有膜选择有效的操作程序提供见解。

ABSTRACTProposal Number: CTS-9983647Principal Investigator: David S. ShollInstitution: Carnegie Mellon UniversityTitle: CAREER: Atomically Detailed Modeling of Transport through Zeolite MembranesZeolites are solid, crystalline materials that are permeated by networks of ordered nanometer-scale pores. These pores are approximately the same size as many small molecules. Because molecules adsorbed inside zeolite pores are always in intimate contact with the walls of the pore, the diffusion rates, and adsorption energies of various chemical species can depend strongly on the size, shape, and functionality of the species. These facts have long been exploited in the applications of zeolites to shape-selective catalysis and adsorption-based separations. Recent years have seen dramatic advances in the reliable synthesis of ultra-thin membranes made from zeolite crystals. An important challenge in the continuing development of these membranes is the need for accurate theoretical models of their performance. This project will focus on developing hierarchical models of molecular transport through zeolite membranes that combine detailed atomic-scale simulations with macroscopic nonequilibrium thermodynamic theories. A vital part of this process will be a series of direct comparisons between theoretical predictions from this research and experimental results obtained by experimental collaborators. Zeolite membranes have a number of attractive properties. From a macroscopic point of view, they have excellent thermal, mechanical, and chemical stability. These properties allow zeolite membranes to be used under conditions that are too harsh for traditional membrane materials such as polymers. Microscopically, the atomically ordered pore structure of zeolites means that zeolite membranes can, in principle, be extremely selective even for mixtures of molecules with very similar shapes and sizes. By developing theoretical models that explicitly account for the atomic-scale structure of zeolite pores, this project will develop a framework for computationally screening libraries of zeolite structures to choose membrane materials that optimize throughput and selectivity for a desired chemical separation. In the shorter term, this work will clarify the fundamental microscopic processes that control molecular transport through zeolite membranes and provide insight into selecting efficient operating procedures for existing membranes.