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促进氢经济。这种能力还可以在限制温室气体排放的同时促进美国的能源独立。然而，这些气体转化为碱性积木化学品的受控转化目前是在高温下进行的，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防止失活途径，该薄膜覆盖层将表面物种限制在活性位置并限制不必要的反应。了解这些过程对于开发具有更高稳定性的新型催化剂是至关重要的，这些催化剂可以降低反应温度和降低整体能耗。具体地说，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，以及这些现象对不断演变的催化剂结构及其降解的影响。此外，这个NSF EPSCoR RII Track-4奖学金项目提供了关于最先进的表征工具的实践培训。在这个项目中开发的技能将被用于增强路易斯安那州立大学目前的工具套件，以探索对地区经济重要的其他与工业相关的反应。使用以二氧化碳为基础的原料会影响许多工业上相关的化学过程，例如甲烷的干法重整。为了最大限度地提高转化率，催化剂设计用于高比表面积和金属中心分散。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，容易结焦和不良副反应。金属熟化及其后续效应背后的机制还知之甚少，在一些研究中，金属分散度的较大变化对催化剂性能的影响很小。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溢出。限制底物/金属成熟可减少焦炭来源的失活，并保持高分散的金属对催化活性负责。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经受住成熟。拟议的工作将与橡树岭国家实验室(ORNL)合作进行，利用他们的术中表征技术和高分辨率像差校正电子显微镜。获得这些独特的能力将有助于使用高级电子显微镜进行实践培训，为路易斯安那州立大学收购对理解表面化学至关重要的STEM、OPERANDO红外和化学吸附分析仪做准备。这一经验将加强PIS的研究概况，特别是在操纵道表面化学领域，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NSF的法定使命，并通过使用基金会的智力优势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.