RII Track-4: NSF: Inhibition of Catalytic Deactivation Mechanisms during CO2 Utilization

将二氧化碳和甲烷转化为燃料的能力可以进一步推动氢经济。这种能力还可以促进美国的能源独立，同时限制温室气体的排放。然而，目前将这些气体控制转化为基本的建筑化学物质是在高温下进行的，这促进了催化剂的长期降解。该项目旨在了解如何使用不可还原的薄膜覆盖层来阻止失活途径，该薄膜覆盖层将表面物质限制在活性位点并限制不必要的反应。了解这些过程是开发新型催化剂的基础，这些催化剂具有更高的稳定性，可以降低反应温度并降低总体能耗。具体来说，PI将与橡树岭国家实验室合作，观察反应表面分子的形成和运动，以及这些现象对催化剂结构演变及其降解的影响。此外，这个NSF EPSCoR RII Track-4奖学金项目提供了最先进的表征工具的实践培训。在此项目中开发的技能将用于增强路易斯安那州立大学目前的工具套件，以探索对区域经济重要的其他工业相关反应。利用基于二氧化碳的原料会影响许多工业相关的化学过程，例如甲烷的干重整。为了最大限度地提高转化，催化剂被设计为高表面积和金属位点分散。然而，克服热力学平衡限制所需的反应条件导致催化剂结构不稳定，容易发生焦化和不良副反应。金属成熟及其后续效应背后的机制尚不清楚，并且在一些研究中，金属分散的大变化对催化剂性能几乎没有影响。PI假设沉积在催化剂衬底上的金属团簇可以使用多孔的、不可还原的薄膜来稳定，以限制金属表面的扩散和生长以及吸附物的溢出。限制底物/金属的熟化减少了焦炭衍生的失活，并保持了催化活性的高金属分散。这一假设是基于最近的文献，这些文献表明多孔壳层在某些条件下可以承受成熟。这项工作将与橡树岭国家实验室（ORNL）合作进行，利用他们的操作中表征技术和高分辨率像差校正电子显微镜。访问这些独特的功能将促进使用高级电子显微镜的实践培训，为路易斯安那州立大学收购STEM， operando红外和化学吸附分析仪做准备，这些分析仪对理解表面化学至关重要。这一经验将加强PIs的研究概况，特别是在operando表面化学领域，并使其他能源密集型工业相关反应的研究成为可能。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The ability to convert CO2 and methane into fuels can further enable the hydrogen economy. This ability can also promote US energy independence while limiting the emission of greenhouse gases. However, the controlled conversion of these gases into basic building block chemicals is currently performed at high temperatures, promoting the long-term degradation of the catalyst. This project aims to understand how deactivation pathways can be prevented using a nonreducible thin-film over-layer that confines surface species to active sites and limits unwanted reactions. Understanding these processes is fundamental to the development of new, catalysts with increased stability that can lower reaction temperatures and decrease overall energy consumption. Specifically, the PI will partner with Oak Ridge National Laboratory to observe the formation and movement of reacting surface molecules and the impact of these phenomena on the evolving catalyst structure and its degradation. Additionally, this NSF EPSCoR RII Track-4 fellowship project provides hands-on training in state-of-the-art characterization tools. The skills developed during this project will be used to enhance the current suite of tools at Louisiana State University to probe other industrially relevant reactions that are important to the regional economy. Utilizing CO2-based feedstocks impacts numerous industrially relevant chemical processes, such as dry reforming of methane. To maximize conversion, catalysts are engineered for high surface areas and metal site dispersions. However, the reaction conditions needed to overcome thermodynamic equilibrium limitations result in the instability of catalyst structures prone to coking and undesirable side reactions. The mechanisms behind metal ripening and their subsequent effects are poorly understood, and in some studies, large changes in metal dispersion can have little effect on catalyst performance. The PI hypothesizes that metal clusters deposited on a catalyst substrate can be stabilized using a porous, nonreducible thin film to limit metal surface diffusion and growth and adsorbate spillover. Limiting substrate/metal ripening reduces coke-derived deactivation and maintains high metal dispersions responsible for the catalytic activity. This hypothesis is based on recent literature, which shows that porous shell layers can withstand ripening at some conditions. The proposed work will be performed in collaboration with Oak Ridge National Lab (ORNL), leveraging their in-operando characterization techniques and high-resolution aberration-corrected electron microscopes. Access to these unique capabilities will facilitate hands-on training with a superior electron microscope in preparation for LSU’s acquisitions of STEM, operando infrared, and chemisorption analyzers vital in understanding surface chemistry. This experience will strengthen the PIs research profile, specifically in the area of operando surface chemistry, and enable the study of other energy-intensive industrially relevant reactions.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.