Collaborative Research: Controlling the Catalytic Properties of SSZ-39 Through Rational Synthesis: An Integrated Computational and Experimental Approach

该项目专注于沸石合成技术的进步--广泛应用于石油和化学工业以及环境污染控制的催化和分子筛材料。具体地说，这项研究的重点是了解被称为有机结构导向剂(OSDA)的化合物促进表现出特定物理和催化性能的沸石晶体的生长过程。研究人员将朝着这一目标整合实验和理论，其中尖端的模拟工具将与实验测量和先进的表征技术相结合。虽然目标沸石是用于柴油发动机排放控制的沸石，但在工作中产生的知识将是广泛的。因此，这些发现将对可再生能源、先进材料生产的改进技术以及制药业生产中间体/产品的新方法产生影响。该项目包括为研究生和本科生提供教育和劳动力培训机会，包括研究组之间对研究生的交叉培训。外展活动将包括K-12外展的互动模块、与新兴能源技术有关的远程学习课程，以及为学生提供的新的实验室安全培训模块。所有这些都可以广泛传播，增加远程学习的选择，随着国家经受住新冠肺炎事件的影响，远程学习将变得更加关键。推动新能源的开发需要扩大我们对基础化学的理解。在催化方面尤其如此，金属交换沸石在工业中得到了积极的利用。新型沸石催化剂进一步应用的一个重要障碍是无法控制局部结构，如活性中心的空间排列，这是沸石科学中的一个重大挑战问题。研究人员的一个研究小组最近的工作表明，通过简单地改变合成中使用的有机结构导向剂的顺式和反式异构体的相对量，有可能控制小孔沸石(称为SSZ-39)框架内的铝排列。因此，本项目的研究目标是通过了解沸石分子筛SSZ-39的成核和生长过程，指导合理合成活性中心可控的沸石。该项目的中心假设是，在八面沸石的相互转化过程中，SSZ-39的成核和生长受八面沸石的溶解控制，SSZ-39是通过溶解的八面沸石晶体上的非均相成核在八面沸石/水界面形成的。研究工作将集中在如何在所有合成参数(异构体比除外)保持固定的系统中控制铝的排列。然而，对沸石中活性中心控制的理解和有效设计的潜力需要实验和计算方法，因为沸石合成是复杂的，如果没有实验和计算研究活动的结合，就不能充分描述沸石。因此，该项目满足了开发综合、多尺度模型以及提高对STEM管道内预测工具的理解和价值的迫切需要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The project focuses on advances in synthesis techniques for zeolites – catalytic and molecular sieve materials used widely in the petroleum and chemical industries, and in environmental pollution control. Specifically, the research focuses on understanding the process by which compounds known as organic structure directing agents (OSDAs) promote the growth of zeolite crystals that display specific physical and catalytic properties. The investigators will integrate experiment and theory toward this goal, where cutting-edge simulation tools will be coupled with experimental measurements and advanced characterization techniques. While the targeted zeolites are those used in diesel engine emissions control, the knowledge generated in the work will be broad-sweeping in scope. As such, the findings will have implications for renewable energy, improved technologies for advanced material production, and new approaches to generating intermediates/products in the pharmaceutical industry. The project incorporates educational and workforce training opportunities for graduate and undergraduate students, including cross-training of graduate students between the research groups. Outreach activities will include interactive modules for K-12 outreach, a distance learning course related to emerging energy technologies, and new lab safety training modules for students. All of those can be widely disseminated, adding to options for remote learning that will become more essential as the nation weathers the impacts of the COVID-19 pandemic.The push for new energy sources has required an expansion in our understanding of fundamental chemistry. This is particularly true with respect to catalysis, with metal exchanged zeolites being actively utilized within industry. A significant roadblock to the further implementation of new zeolite catalysts is the general inability to control local structure such as active site spatial arrangement, a grand challenge problem in zeolite science. Recent work by one of the investigators’ research groups indicates that it is potentially possible to control the aluminum arrangement within the framework of a small pore zeolite (known as SSZ-39) by simply varying the relative amount of the cis and trans isomer of the organic structure directing agent used in synthesis. The research objective of the project is thus to guide the rational synthesis of zeolites with controlled active site arrangement by understanding the nucleation and growth of SSZ-39 from a faujasite zeolite. The central hypothesis of the project is that the nucleation and growth of SSZ-39, in an interconversion process from faujasite, is controlled by the dissolution of the faujasite, with the SSZ-39 forming at the faujasite/aqueous interface via heterogeneous nucleation off the dissolving faujasite crystal. Research efforts will focus on ways to control the aluminum arrangement in a system where all synthesis parameters (save the isomer ratio) are held fixed. However, the understanding—and potential for efficient design—of active site control in zeolites requires both experimental and computational methodologies, as zeolite synthesis is complex and cannot be adequately described without advances in the marriage of experimental and computational research activities. The project thus addresses a critical need to develop comprehensive, multi-scale models and to advance the understanding and value of predictive tools within the STEM pipeline.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.