EAGER: Collaborative Research: Consequences of Co-Adsorbed Chlorine on Surface Dynamics and Selectivity in Ethylene Epoxidation on Silver Catalysts

EAGER：合作研究：共吸附氯对银催化剂上乙烯环氧化反应的表面动力学和选择性的影响

基本信息

批准号：
1942015
负责人：
David Flaherty
金额：
$ 11.89万
依托单位：
University of Illinois at Urbana-Champaign
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-12-01 至 2022-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1942015&HistoricalAwards=false
关键词：
EAGER Collaborative Research Consequences Co

项目摘要

Ethylene oxide (EO) is a major commodity chemical used in the production of materials, industrial solutions, surfactants and consumer goods. EO is manufactured via a catalytic reaction between ethylene and oxygen gas utilizing highly complex catalysts that have evolved over the years primarily through industrial research involving experimental screening of a large array of catalytic, promoter, and stabilizing materials. While those efforts have led to high-performing catalysts containing five or more promoting materials, there remains significant opportunity to improve the catalyst technology. State-of-the art theory, machine learning, spectroscopic and reaction analysis methods will be combined to better understand the role of chlorine, one of the key promoting elements, and identify opportunities for increasing its effectiveness. Higher-performing EO catalysts would improve process energy efficiency, reduce emissions, and promote U.S. competitiveness in a chemical market sector that accounted for $45B in 2016. Among the many different combinations of promoters reported in commercial EO catalysts, chlorine (Cl) is the most ubiquitous promoter, and its addition to an otherwise unmodified silver (Ag) catalyst leads to the greatest increase in selectivity to EO. Reactant and promoter-induced surface dynamics and reconstruction have long been known to play a critical role in many catalytic reactions. The study combines catalyst synthesis, spectroscopic characterization, reactivity testing, and machine-learning enhanced molecular simulations, to explore the dynamic nature of the Cl-promoted Ag surface under reaction conditions. The bottom-up approach to synthesis and characterization yields itself to several opportunities for reconciling conflicting spectroscopic assignments in the literature, mechanistic proposals for this system, and hypotheses for the mode of action of Cl through the combination of cutting-edge computational and experimental methods. Specifically, the study will utilize efficient computational approaches for modeling dynamic evolution of systems with high configurational complexity. Time-averaged simulated Raman spectra derived from molecular dynamics simulations will be used in conjunction with multi-variate curve resolution of experimental Raman spectra to make molecularly precise assignments for different surface oxygen species and the influence of Cl on their structure. The transient behavior of these systems will also be tied to observations at steady-state operation at conditions relevant for industrial systems. The collaborative nature of the project will provide opportunities for cross-exposure of graduate students from the two research groups to theoretical and experimental methods, thereby teaching skills for effective research collaboration. The methodologies developed in the research and their application will be integrated into graduate courses taught by the co-investigators to demonstrate the importance of embracing complexity of catalytic systems, even within fundamental studies.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.

环氧乙烷 (EO) 是一种主要的日用化学品，用于生产材料、工业溶液、表面活性剂和消费品。环氧乙烷是通过乙烯和氧气之间的催化反应生产的，使用的是多年来主要通过工业研究发展而来的高度复杂的催化剂，涉及大量催化、促进剂和稳定材料的实验筛选。虽然这些努力已经产生了含有五种或更多促进材料的高性能催化剂，但仍然存在改进催化剂技术的重大机会。最先进的理论、机器学习、光谱和反应分析方法将相结合，以更好地了解关键促进元素之一氯的作用，并找到提高其有效性的机会。更高性能的 EO 催化剂将提高工艺能源效率、减少排放，并提高美国在 2016 年占 $45B 的化学品市场领域的竞争力。在商业 EO 催化剂中报道的许多不同的促进剂组合中，氯 (Cl) 是最重要的最普遍的促进剂，将其添加到未经修饰的银 (Ag) 催化剂中可最大程度地提高 EO 的选择性。人们早就知道反应物和促进剂诱导的表面动力学和重构在许多催化反应中发挥着关键作用。该研究结合了催化剂合成、光谱表征、反应性测试和机器学习增强分子模拟，以探索反应条件下 Cl 促进的 Ag 表面的动态性质。自下而上的合成和表征方法为协调文献中相互冲突的光谱分配、该系统的机制建议以及通过尖端计算和实验方法相结合的 Cl 作用模式假设提供了多种机会。具体来说，该研究将利用高效的计算方法对具有高配置复杂性的系统的动态演化进行建模。由分子动力学模拟得出的时间平均模拟拉曼光谱将与实验拉曼光谱的多元曲线分辨率结合使用，以对不同表面氧物种以及 Cl 对其结构的影响进行分子精确分配。这些系统的瞬态行为也将与工业系统相关条件下稳态运行的观察结果联系起来。该项目的协作性质将为两个研究小组的研究生提供交叉接触理论和实验方法的机会，从而传授有效研究合作的技能。研究中开发的方法及其应用将被纳入共同研究人员教授的研究生课程中，以证明即使在基础研究中也考虑催化系统复杂性的重要性。该奖项反映了 NSF 的法定使命，并被认为值得支持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。