NSF-GACR: Atoms to nanoparticles to atoms - predicting evolving catalyst activity under inherently transient conditions

NSF-GACR：原子到纳米粒子到原子 - 预测固有瞬态条件下不断变化的催化剂活性

• 批准号: 2227016
• 负责人: William Epling
• 金额: $ 42.27万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2227016&HistoricalAwards=false
• 关键词: NSF; GACR; Atoms; nanoparticles; atoms

Metal-exchanged zeolites are common catalysts, used in applications ranging from fossil fuel and biomass hydrocarbon transformations, to CO2 capture, and mitigation of diesel engine exhaust emissions. Describing the active sites for many of these reactions, under reaction conditions, remains elusive, thus limiting improvements in catalyst design. Depending on the reaction conditions, ion-exchanged metal atoms, solvated ions, dimers, trimers, small clusters, and nanoparticles have all been invoked as active catalytic sites. Further, for some reactions, several of these species may co-exist. The overarching goal of the project - an international collaboration with the University of Chemistry and Technology in Prague, Czechoslovakia (UCTP) - is to characterize and predict changes in the type and amount of active catalytic species in metal-containing zeolites during dynamic catalyst/surface changes under reaction conditions, and thereby assess the molecular origin for changes in activity. The resulting insights will lead to improved catalyst designs enabling more efficient use of expensive noble metals, improved energy efficiency of catalytic processes, and increases in catalyst durability and time-on-stream. This project will develop and use methodologies to quantify different types of copper (Cu) and palladium (Pd) species in zeolites, and how they are impacted by typical reaction environment conditions and temperatures. These two metals were chosen, along with SSZ and BEA zeolites, due to their use as selective catalytic reduction (SCR) catalysts and passive NOx adsorbers (PNA), critical technologies in emissions control catalysis. Probe molecule reactions, as well as infrared and X-ray spectroscopic techniques, will be used to isolate individual Cu and Pd moieties. Example probe reactions include CO titration of multinuclear Cu sites, NO+NH3 titration of ion-exchanged Cu, and NO adsorption to titrate ion-exchanged Pd sites. Various reaction conditions will be studied that are likely to induce changes in active species. Those include temperature, oxidizing vs. reducing gas mixtures, and water content. In addition, the project will investigate how exposure to sulfur dioxide (SO2) - a common catalyst poison - influences changes in active species. Beyond active site identification, the project will examine the extent to which the dynamic changes in active sites are reversible. Identification of operating conditions that promote reversible changes are critical, as reversibility allows catalyst regeneration, thus extending catalyst lifetimes. Experimental data identifying and quantifying individual types of active sites, and how those quantities change with environment, will be used to build predictive kinetic SCR and PNA models that include evolution of individual active site concentration as a function of gas composition, temperature, and time. Beyond the technical aspects, the project includes research training opportunities for both graduate and undergraduate students and opportunities for collaborative exchange between American and Czech researchers and their graduate students.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.

金属交换的沸石是常见的催化剂，用于从化石燃料和生物质烃转化到二氧化碳捕获以及缓解柴油发动机排气排放的应用。在反应条件下，描述许多这些反应的活动位点仍然难以捉摸，从而限制了催化剂设计的改进。 根据反应条件，将离子交换的金属原子，溶剂化离子，二聚体，三聚体，小簇和纳米颗粒都称为活性催化位点。 此外，对于某些反应，其中一些物种可能共存。 该项目的总体目标 - 捷克斯洛伐克（UCTP）的化学与技术大学的国际合作 - 是为了表征和预测在反应条件下动态催化剂/表面变化中含金属的沸石中活性催化物种的类型和数量的变化，从而评估了分子起源的活动变化。 由此产生的见解将导致改进的催化剂设计，从而更有效地利用昂贵的高贵金属，提高催化过程的能源效率，并提高催化剂耐用性和时间流。该项目将开发和使用方法来量化沸石中不同类型的铜（CU）和钯（PD）物种，以及它们如何受到典型的反应环境条件和温度的影响。由于它们用作选择性催化还原（SCR）催化剂和被动NOX吸附剂（PNA），因此选择了这两种金属，以及SSZ和BEA沸石，因此排放控制催化催化剂中的关键技术。 探针分子反应以及红外和X射线光谱技术将用于分离单个Cu和PD部分。示例探针反应包括对多核Cu位点的CO滴定，离子交换Cu的无+NH3滴定，以及对滴定离子交换的PD位点的吸附。 将研究各种反应条件，这些条件可能会引起活性物种的变化。 其中包括温度，氧化与减少气体混合物以及水含量。 此外，该项目将研究暴露于二氧化硫（SO2）的暴露（一种常见的催化剂毒药）如何影响活性物种的变化。 除了主动站点识别外，该项目还将检查活动站点的动态变化可逆的程度。 鉴定促进可逆变化的工作条件至关重要，因为可逆性允许催化剂再生，从而延长了催化剂的寿命。 实验数据识别和量化各个类型的活性位点，以及这些数量如何随环境而变化，将用于构建预测性动力学SCR和PNA模型，其中包括单个活性位点浓度的演变，这是气体组成，温度和时间的函数。 除技术方面外，该项目还包括研究生和本科生的研究培训机会以及美国和捷克研究人员及其研究生之间的合作交流机会。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估来评估的。