Understanding the Chemical Activity of Oxide-supported Bimetallic Clusters

在这个由化学系化学催化计划资助的项目中，Donna Chen教授和John Monnier教授将研究二氧化钛负载的铂-Re团簇作为模型系统，用于开发新的催化剂，将乙醇等生物可再生燃料转化为用于燃料电池的清洁氢气。所提出的研究将通过提供关于双金属相互作用、在金属-团簇界面上发生的反应、被氧化的Re的活性以及这些性质与团簇大小的依赖关系的基础知识，来指导高性能铂-Re/二氧化钛催化剂的开发。此外，拟议的工作将提供反应动力学、机理和活性中心性质的详细知识。在超高真空气相沉积的铂、稀土和铂-稀土团簇上，研究了乙醇与氧气和水的氧化重整反应(自热重整)。乙醇部分氧化和水-气变换反应将在模型催化剂上进行独立研究，这两个反应都发生在自热重整过程中。利用扫描隧道显微镜、低能离子散射、X射线光电子能谱、程序升温脱附和高分辨电子显微镜等技术对双金属团簇表面进行了全面表征。使用与UHV系统耦合的环流反应器研究团簇的催化活性，并使用红外反射吸收光谱在催化条件下研究表面中间体。PIS将培训表面科学和催化领域的研究生和本科生，更重要的是，在表面科学和催化剂性能之间重叠的领域。此外，PIs将通过美国加州大学现有的计划，积极参与促进当地社区对纳米科学和纳米技术研究的了解。许多商业多相催化剂由氧化物载体表面的双金属材料组成。这一研究项目将有助于更好地理解如何通过两种金属之间的相互作用以及金属与载体之间的相互作用来调整催化活性。具体地说，这项工作将有助于合理设计含铂和Re的催化剂，用于分解乙醇等可再生生物燃料，以清洁氢用于氢燃料电池。此外，私营部门将通过南加州大学现有的项目，积极参与促进当地社区对纳米科学和纳米技术研究的了解。

In this project funded by the Chemical Catalysis Program in the Division of Chemistry, Professors Donna Chen and John Monnier will study titania-supported Pt-Re clusters as model systems for developing new catalysts for the conversion of bio-renewable fuels like ethanol to clean H2 for use in fuel cells. The proposed studies will guide the development of superior Pt-Re/TiO2 catalysts by providing fundamental understanding of how surface chemistry is controlled by: bimetallic interactions, reactions occurring at the metal-cluster interface, the activity of oxidized Re, and the dependence of these properties on cluster size. In addition, the proposed work will provide detailed knowledge of reaction kinetics, mechanisms and the nature of the active sites. Oxidative reforming of ethanol with O2 and water (autothermal reforming) will be investigated on vapor-deposited Pt, Re, and Pt-Re clusters prepared in ultrahigh vacuum. Partial oxidation of ethanol and the water-gas shift reaction will be studied on the model catalysts to independently investigate these two reactions, which both occur in autothermal reforming. The bimetallic cluster surfaces will be fully characterized using techniques such as scanning tunneling microscopy, low energy ion scattering, X-ray photoelectron spectroscopy, temperature programmed desorption and high resolution transmission electron microscopy. The catalytic activities of the clusters will be investigated using a recirculation loop reactor coupled to the UHV system, and surface intermediates will be studied under catalytic conditions using infrared reflection absorption spectroscopy. The PIs will train graduate and undergraduate students in the areas of surface science and catalysis, and more importantly in the area of overlap between surface science and catalyst performance. Furthermore, the PIs will actively participate in efforts to promote understanding of nanoscience and nanotechnology research in the local community via existing programs at USC.Many commercial heterogeneous catalysts consist of bimetallic materials on oxide support surfaces. This research project will lead to better understanding of how catalytic activity can be tailored through interactions between the two metals and interactions between the metals and the support. Specifically, this work will contribute to the rational design of platinum and rhenium containing catalysts for the decomposition of renewable biofuels like ethanol to clean hydrogen for use in hydrogen fuel cells. Furthermore, the PIs will actively participate in efforts to promote understanding of nanoscience and nanotechnology research in the local community via existing programs at USC.