Designing New Methods to Exploit Intercrystalline Transformations in Zeolite Synthesis

非技术概述沸石是由氧化铝和二氧化硅组成的多孔晶体，由于其独特的性质，在商业应用中大量用作催化剂和吸附剂。尽管它们广泛用于从能源到医学的过程中，但沸石合成的复杂性使得人们很难理解这些材料是如何形成的，以及可以开发什么方法来控制和定制它们的特性。该项目由材料研究部的固态和材料化学计划支持，采用实验和计算技术相结合的方法来研究一个越来越受关注的主题，种子辅助合成，其中将晶种引入生长溶液中以促进形成具有理想尺寸，形状和组成的沸石晶体。在沸石合成中，从小晶体开始合成的引晶机制在很大程度上未被探索，但有限的研究表明，这些方法能够实现传统途径无法获得的材料性质。休斯顿大学的研究小组对此进行了研究，以提高对晶体到晶体转变的基本理解，旨在建立合理设计的指导方针。作为该项目的一部分，他们研究了种子辅助合成的机制，开发了制备新材料的新方法，并使用了独特的设备，可以在分子水平上直接观察晶体表面的生长。该项目的智力价值是提高了晶体工程的基础知识，使发现新的路线来定制沸石的性能，并提高了对沸石结晶的复杂过程的理解。该项目的更广泛影响是技术的进步，为大规模沸石生产和应用带来了变革性成果。考虑到沸石在商业过程中的大量使用，可以从这些研究中获得显著的社会经济效益。此外，该奖项还扩大了与美国宇航局和当地高中的项目，并通过休斯顿大学的外联联络员进行协调。首席研究员还提供各级研究的机会（K-12，本科生和研究生），并促进研究和教育，重点是增加入学率和保留代表性不足的少数民族学生，有风险的学生，技术概述ZEERTAINS是结晶微孔铝硅酸盐，具有出色的水热稳定性和可调酸度，适用于从能源到药沸石合成中的一种新兴方法是使用晶种或沸石间转化，其中初始（母体）结构转化为产物（子体），但在复杂的非经典结晶途径中的晶种机制在很大程度上未被探索。通过该项目，由材料研究部的固态和材料化学计划支持，研究人员的目标是推进对晶体到晶体转化的基本理解，目的是在机器学习的指导下找到经验规则，以预测和控制母体沸石转化为相同或不同晶体结构的产品。具体而言，他们研究（1）通过仔细选择母-子组合来阐明控制非经典晶种机制的因素，从而在晶体工程中使用晶种;（2）通过无有机物的晶种辅助合成来生产自柱撑沸石的新方案;以及（3）使用用于扫描探针显微镜的独特的液体池来分析晶体-晶体转换，以捕获时间-进行沸石间转化的沸石表面的解析图像。该项目的智力价值是专注于解决沸石结晶方面的知识空白，需要进行更多的基础研究，以更深入地了解能够通过简单，有效的过程选择性控制成核和生长的方法。控制沸石的物理化学性质是不平凡的，但可以通过种子辅助技术来实现。这项研究有可能建立一个更好的理解晶间过渡，以推进复杂的沸石生长途径的理解，并建立晶体工程的设计原则，作为应用研究的基础，超出了本项目的范围。该项目更广泛的影响是合成具有传统方法无法实现的最佳性能的沸石的潜力。考虑到沸石在商业过程中的广泛使用，可以从这些研究中获得显著的社会经济效益。该项目还促进了K-12、本科和研究生水平的项目，以促进研究和教育，重点是提高少数民族学生、风险学生和工程领域女性的入学率和保留率。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。

Non-Technical SummaryZeolites are porous crystals comprised of alumina and silica that are heavily used as catalysts and adsorbents in commercial applications owing to their unique properties. Despite their widespread use in processes spanning from energy to medicine, the complexity of zeolite synthesis makes it difficult to understand how these materials form and what methods can be developed to control and tailor their properties. This project, which is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, employs a combination of experimental and computational techniques to investigate a topic of growing interest, seed-assisted synthesis, where crystal seeds are introduced into growth solutions to promote the formation of zeolite crystals with desirable size, shape, and composition. Mechanisms of seeding, that is starting a synthesis from a small crystal, are largely unexplored in zeolite synthesis, yet limited studies reveal that these processes are capable of achieving material properties that are otherwise inaccessible by conventional routes. The research group at the University of Houston studies this to improve the fundamental understanding of crystal-to-crystal transformations with the aim of establishing guidelines for rational design. As part of this project, they investigate mechanisms of seed-assisted synthesis, the development of new methods to prepare novel materials, and the use of unique equipment that permit direct visualization of crystal surface growth at a molecular level. The intellectual merit of this project is an improved fundamental knowledge of crystal engineering that enables discovery of new routes to tailor the properties of zeolites, and an improved understanding of complex processes underlying zeolite crystallization. The broader impacts of this project are the advancement of techniques with transformative outcomes for large-scale zeolite production and applications. Considering the large use of zeolites in commercial processes, a significant socioeconomic benefit can be derived from these investigations. Additionally, this award expands a program with NASA and local high schools, coordinated through outreach liaisons at the University of Houston. The principle investigator also offers opportunities for research at all levels (K-12, undergraduate, and graduate) and promotes research and education with an emphasis on increased matriculation and retention of under-represented minority students, at risk students, and women in engineering.Technical SummaryZeolites are crystalline microporous aluminosilicates with exceptional hydrothermal stability and tunable acidity for commercial applications ranging from energy to medicine. An emerging approach in zeolite synthesis is the use of crystal seeding or interzeolite transformations where an initial (parent) structure is converted into a product (daughter), yet the mechanisms of seeding in complex, nonclassical pathways of crystallization are largely unexplored. With this project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, researchers aim to advance the fundamental understanding of crystal-to-crystal transformations with the goal of finding empirical rules, guided by machine learning, to predict and control the conversion of a parent zeolite into a product of identical or different crystal structure. Specifically, they study (1) the use of seeds in crystal engineering through the careful selection of parent-daughter combinations to elucidate factors governing nonclassical seeding mechanisms; (2) new protocols to produce self-pillared zeolites via an organic-free, seed-assisted synthesis; and (3) analyzing crystal-crystal transformations using a unique liquid cell for scanning probe microscopy to capture time-resolved images of zeolite surfaces undergoing interzeolite conversion. The intellectual merit of this project is the focus on addressing knowledge gaps in zeolite crystallization where more fundamental studies are required to provide deeper insight into methods capable of selectively controlling nucleation and growth through facile, efficient processes. Controlling the physicochemical properties of zeolites is nontrivial, but can be accomplished through seed-assisted techniques. This research has the potential to establish an improved understanding of intercrystalline transitions to advance understanding of complex zeolite growth pathways and establish design principles for crystal engineering as a foundation for applied studies that extend beyond the scope of this project. The broader impacts of this project are the potential to synthesize zeolites with optimal properties that cannot be achieved by conventional methods. Considering the widespread use of zeolites in commercial processes, a significant socioeconomic benefit can be derived from these investigations. This project also facilitates programs at the K-12, undergraduate, and graduate levels to promote research and education with an emphasis on increased matriculation and retention of under-represented minority students, at risk students, and women in engineering.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.