Bridging Homogeneous and Heterogeneous Catalysis: In-Situ Characterization and Theory of Supported Metal Complexes

催化在化工生产、能源转化、环境保护等方面发挥着核心作用。一个中心挑战是连接均相和非均相催化剂：载体上的金属络合物展示了它们之间的一些最好的联系。然而，利用原位技术对这些催化剂进行表征是非常缺乏的，这些技术可以用来研究这些催化剂在其工作状态下的结构。本研究的目的是发展和展示原位光谱分析方法和流动反应技术，用于研究在烷烃和烯烃等气相反应物存在下的氧化物负载过渡金属络合物催化剂。这些技术包括原位红外光谱、X射线近边吸收光谱和扩展X射线吸收精细结构光谱。理论方法将利用密度泛函理论。该催化剂将包括氧化物负载的Ta、Cr、Zr络合物和一种新的沸石负载的铂络合物。结合表征数据和理论，可以确定原子尺度的催化剂结构和催化反应速率如何取决于吸附物和载体的结构和组成，以及反应条件。这是识别活性中间体和建立反应机理的绝佳机会。最大的挑战将是预测催化活性。这项研究将通过一个导师计划产生强大而广泛的影响，该计划让来自代表人数不足的群体的学生参与研究项目。一项专注于纳米科学和技术的跨学科IGERT计划已经到位。

Catalysis plays a central role in chemical manufacturing, energy conversion, and environmental protection. A central challenge is to bridge homogeneous and heterogeneous catalysts: metal complexes on supports illustrate some of the best connections between them. However, there is a striking lack of their characterization with in situ techniques, which allow the structures of these catalysts to be investigated in their working state. The goal of this research is to develop and demonstrate methods of in situ spectroscopy and flow reactor techniques for investigation of oxide-supported transition metal complex catalysts in the presence of gas-phase reactants, such as paraffins, and olefins. The techniques include in situ IR, X-ray absorption near edge structure, and extended X-ray absorption fine structure spectroscopies. Theoretical approaches will utilize density functional theory. The catalysts will include oxide-supported Ta, Cr, and Zr complexes and a new zeolite-supported Pt complex. The combined characterization data and theory will permit determination of how the atomic-scale catalyst structure and the rates of the catalytic reactions depend on the structure and composition of the adsorbate and the support, as well as the reaction conditions. There is an excellent opportunity to identify reactive intermediates and establish reaction mechanisms. The grand challenge will be to predict catalytic activities. The research will have strong broader impacts through a mentorship program that involves students from underrepresented groups in research projects. An interdisciplinary IGERT program is in place that focuses on nanoscience and technology.