Designing New Methods to Exploit Intercrystalline Transformations in Zeolite Synthesis

点击翻译按钮获取中文摘要

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.