RII Track-4:NSF: Design of zeolite-encapsulated metal phthalocyanines catalysts enabled by insights from synchrotron-based X-ray techniques

RII Track-4：NSF：通过基于同步加速器的 X 射线技术的见解实现沸石封装金属酞菁催化剂的设计

• 批准号: 2327267
• 负责人: James Shogren-Harris
• 金额: $ 20.6万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2327267&HistoricalAwards=false
• 关键词: RII; Track; NSF; Design; zeolite

Heterogeneous catalysts are used in a wide range of industries, including the chemicals and automotive sectors, to enable reactions to proceed under milder conditions with higher selectivity towards desired products. These materials have complex structures that are difficult to define, and therefore difficult to further improve. In this project, model catalysts will be developed that have well defined structures, in order to determine which aspects of these materials are beneficial for catalysis. Using state-of-the-art X-ray techniques available only at a handful of laboratories in the world (known as synchrotrons), the research team will precisely determine the structures of these materials during reaction. These measurements are not possible in university laboratories. Through this project, a graduate student and a professor will gain expertise in performing these measurements and analyzing the resultant data, allowing the researchers to share their knowledge with diverse collaborators across the state of Alabama. Through those efforts, this project will increase access to synchrotron-based X-ray techniques for researchers in Alabama, allowing the state to be increasingly competitive in attracting federal funding and private investment in scientific research. This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows project will provide a fellowship to an Assistant Professor and training for a graduate student at the University of Alabama Tuscaloosa. This work would be conducted in collaboration with researchers at the SLAC National Accelerator Laboratory.Development of structure function relationships necessary for rational design of heterogeneous catalysts requires detailed knowledge of the structure of inorganic solids at the atomic level, including of the electronic structures of metal atoms and the local connectivity between atoms as a function of process conditions. Laboratory-scale techniques can quantify the number of metal binding sites but cannot identify and quantify their structural features (oxidation states, coordination numbers, and metal-ligand bond distances) during reaction. The best technique for these measurements is operando synchrotron-based X-ray absorption spectroscopy (XAS), wherein quantitative XAS data are collected over a working catalyst while reaction rates are measured simultaneously. The project will develop a fundamental understanding of the structure of zeolite-encapsulated metal-phthalocyanine complexes (MPCs) and the chemistries they mediate by taking extended visits to the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC National Accelerator Laboratory (SLAC). Combining XAS with in situ wide angle x-ray scattering (WAXS) and infrared spectroscopy measurements allows monitoring of the structure of both the primary binding sites, the structure of the zeolitic pores that confine them, and the intermediates present during catalysis. The research team will gain expertise in XAS and WAXS by working with recognized experts in these techniques. The materials characterized in this proposal avoid heterogeneities in local configurations of primary binding sites that are unavoidable for many other zeolite-, doped-carbon-, and MOF-based catalysts. These catalysts will be more stable than analogous MPC complexes in solution, allowing for gas-phase chemistry over single-site catalysts. This will be the first use of faujasite zeolite encapsulated MPC complexes, to our knowledge, for gas-phase oxidation reactions with N2O, and thus the first measurements of in situ or operando XAS spectra of these catalysts during this reaction. By gaining an understanding of the structure and stability of these materials under reaction conditions, we will describe catalysis over heterogeneous single-atom complexes without distractions from variation in the local configuration of the primary binding sites and the pores that confine them.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.

多相催化剂广泛应用于化工和汽车行业等行业，使反应能够在更温和的条件下进行，并以更高的选择性生成所需的产物。这些材料具有难以定义的复杂结构，因此难以进一步改进。在该项目中，将开发具有明确结构的模型催化剂，以确定这些材料的哪些方面有利于催化。研究团队将利用世界上仅有少数实验室提供的最先进的 X 射线技术（称为同步加速器），精确确定这些材料在反应过程中的结构。这些测量在大学实验室中是不可能的。通过这个项目，一名研究生和一名教授将获得执行这些测量和分析结果数据的专业知识，使研究人员能够与阿拉巴马州的不同合作者分享他们的知识。通过这些努力，该项目将为阿拉巴马州的研究人员提供更多基于同步加速器的 X 射线技术，使该州在吸引联邦资金和私人科学研究投资方面更具竞争力。该研究基础设施改进 Track-4 EPSCoR 研究人员项目将为阿拉巴马大学塔斯卡卢萨分校的一名助理教授提供奖学金，并为一名研究生提供培训。这项工作将与 SLAC 国家加速器实验室的研究人员合作进行。合理设计多相催化剂所需的结构函数关系的开发需要详细了解原子水平的无机固体结构，包括金属原子的电子结构以及原子之间的局部连接性作为过程条件的函数。实验室规模的技术可以量化金属结合位点的数量，但无法识别和量化反应过程中的结构特征（氧化态、配位数和金属-配体键距）。这些测量的最佳技术是基于操作同步加速器的 X 射线吸收光谱 (XAS)，其中通过工作催化剂收集定量 XAS 数据，同时测量反应速率。该项目将通过对 SLAC 国家加速器实验室 (SLAC) 的斯坦福同步辐射光源 (SSRL) 的长期访问，对沸石封装的金属酞菁络合物 (MPC) 的结构及其介导的化学作用有一个基本的了解。将 XAS 与原位广角 X 射线散射 (WAXS) 和红外光谱测量相结合，可以监测主要结合位点的结构、限制它们的沸石孔的结构以及催化过程中存在的中间体。研究团队将通过与这些技术领域的知名专家合作，获得 XAS 和 WAXS 方面的专业知识。该提案中表征的材料避免了主要结合位点局部构型的异质性，这对于许多其他沸石基、掺杂碳基和 MOF 基催化剂来说是不可避免的。这些催化剂在溶液中比类似的 MPC 配合物更稳定，允许在单中心催化剂上进行气相化学。据我们所知，这将是八面沸石封装的 MPC 配合物首次用于与 N2O 的气相氧化反应，因此也是首次测量该反应过程中这些催化剂的原位或操作 XAS 光谱。通过了解这些材料在反应条件下的结构和稳定性，我们将描述对异质单原子复合物的催化作用，而不会干扰主要结合位点和限制它们的孔的局部构型的变化。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。