A Reactive Approach to Model Zeolite Synthesis

沸石分子筛是一种具有可容纳小分子的孔径的材料，是催化过程和分子分离的重要材料。 沸石具有多种化学性质和形貌，因此这些材料的合理设计对于创造和优化新的沸石结构至关重要。 结构导向剂是将沸石合成过程导向明确定义的结构的分子。 本研究计画将发展一种在结构导向分子影响下，以溶胶-凝胶法合成沸石之合理设计方法。 研究人员将研究使用反应分子模型来研究硅和氧化铝基系统中的溶胶-凝胶过程，有和没有结构导向剂。 该项目还包括与德国的研究小组开展的一些合作活动。 该研究项目作为研究生和本科生进行尖端研究的培训基地。 研究人员还将开发一个新的新生研讨会“网络工程新材料：它是什么，我需要它做什么？“这个研讨会课程将向本科生介绍现代计算材料设计。 研究人员还将提供一个暑期学校/研讨会，介绍新的模拟方法，以使更多的高级学生受益。该研究项目将集中在两种类型的沸石，ZSM-5和LTA，以及几种结构导向剂（例如，四烷基铵离子和氢氧化钠）。 这项工作的目标是：（1）沸石前体/前体混合物的模型构建和批量模拟，以验证和优化反应模型，并使早期沸石结构的形态研究成为可能;（2）在结构导向剂类限制中模拟前体及其反应。将研究结构导向剂对形态形成的影响，并与现有的实验数据进行比较。阐明了结构导向剂的结构排列和反应活性之间的相互作用;（3）模拟了类沸石结构中的结构导向剂分子。 将模拟预成型沸石结构，并分析它们与结构导向剂的相互作用。 这些模拟对于理解从最终沸石结构中除去结构导向剂的煅烧步骤将是特别相关的。沸石骨架的热稳定性和水热稳定性也将被研究。最后，研究人员将对由前体/结构导向剂/溶剂混合物组成的完整系统进行模拟，以研究沸石形成过程的所有阶段。 最终，该研究项目将深入了解沸石的形成条件，并获得一种经过充分测试的方法，可以推广到描述其他催化活性材料的形成。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Zeolites are materials with pore sizes that can accommodate small molecules, and they are important materials for catalytic processes and molecular separations. Zeolites display a wide variety of chemistries and morphologies, so the rational design of these materials is crucial to create and optimize new zeolite structures. Structure directing agents are molecules that guide the zeolite synthesis process towards well-defined structures. This research project will develop a methodology for the rational design of sol-gel synthesized zeolites prepared under the influence of structure directing molecules. The researchers will investigate using reactive molecular modeling to study sol-gel processes in silica- and alumina-based systems, with and without structure directing agents. The project also includes some collaborative activities with research groups in Germany. The research project serves as a training ground for graduate and undergraduate students to perform cutting edge research. The researchers will also develop a new freshman seminar on "Cyber Engineering New Materials: What is it and what do I need it for?" This seminar course will introduce undergraduate students to modern computational materials design. The researchers also will offer a summer school / workshop on novel simulation methods to benefit more advanced students.This research project will focus on two types of zeolites, ZSM-5 and LTA, and several structure directing agents (e.g., tetraalkylammonium ions and sodium hydroxide). The goals of this work are to : (1) model building and bulk simulations of zeolite precursors/precursor mixtures to validate and optimize the reactive model and enable studies of the morphology of early zeolite structures; (2) perform simulations of precursors and their reactions in structure directing agent-like confinement. The influence of structure directing agents on morphology formation will be studied and compared to existing experimental data. The interplay of structure directing agent structure arrangement and reactivity will be elucidated; and (3) simulate structure directing agent molecules in zeolite-like structures. Preformed zeolite structures will be simulated and their interactions with structure directing agents will be analyzed. These simulations will be particularly relevant for understanding the calcination step in which the structure directing agent is removed from the final zeolite structure. The thermal and hydrothermal stability of zeolite frameworks will be studied too. Finally, researchers will perform simulations of the complete system, consisting of precursor / structure directing agent / solvent mixtures, to study all stages of the zeolite formation process. Ultimately, the research project will provide insights into the formation conditions of zeolites and obtain a well-tested methodology that can be generalized to describe the formation of other catalytically active materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.