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

该项目重点关注沸石合成技术的进步——沸石是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。 具体来说，该研究的重点是了解有机结构导向剂（OSDA）化合物促进具有特定物理和催化特性的沸石晶体生长的过程。 研究人员将整合实验和理论来实现这一目标，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，但工作中产生的知识范围将广泛。因此，这些发现将对可再生能源、先进材料生产技术的改进以及制药行业生产中间体/产品的新方法产生影响。该项目为研究生和本科生提供教育和劳动力培训机会，包括研究小组之间研究生的交叉培训。 外展活动将包括 K-12 外展互动模块、与新兴能源技术相关的远程学习课程以及针对学生的新实验室安全培训模块。 所有这些都可以广泛传播，增加了远程学习的选择，随着国家经受住 COVID-19 大流行的影响，远程学习将变得更加重要。推动新能源需要扩大我们对基础化学的理解。对于催化来说尤其如此，金属交换沸石在工业中得到积极利用。进一步应用新型沸石催化剂的一个重要障碍是普遍无法控制局部结构，例如活性位点空间排列，这是沸石科学中的一个重大挑战问题。研究人员之一的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，该项目的研究目标是通过了解八面沸石中 SSZ-39 的成核和生长来指导活性位点排列受控的沸石的合理合成。该项目的中心假设是，在八面沸石的互变过程中，SSZ-39 的成核和生长是由八面沸石的溶解控制的，SSZ-39 通过溶解的八面沸石晶体的异质成核在八面沸石/水界面处形成。研究工作将集中于控制所有合成参数（保留异构体比例）固定的系统中铝排列的方法。然而，对沸石活性位点控制的理解和有效设计的潜力需要实验和计算方法，因为沸石合成很复杂，如果没有实验和计算研究活动结合的进展，就无法充分描述。因此，该项目满足了开发全面、多尺度模型并提高对 STEM 管道内预测工具的理解和价值的迫切需求。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值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.