Long-Term Research Visit to Japan: Electronic Properties and Catalytic Activity of Supported Metal Oxides

9819369 Oyama该奖项提供资金支持S. Ted Oyama，弗吉尼亚理工学院和州立大学化学工程系，与东京大学化学系Yasuhiro Iwasawa和Kiyotaka Asakura博士以及日本东京工业大学资源利用研究实验室Kazunori Domen博士合作。 这些合作者将对氧化物催化剂的反应性进行研究。 该项目涉及研究氧化物表面的电子结构和催化活性之间的关系。 初步工作表明，在醇的氧化反应中，有一个强大的影响，负载氧化物的催化剂，导致在周转率的数量级的差异，对活化能的影响不大。 这可以通过涉及电子转移到催化位点的速率决定步骤来解释。 因此，对有效催化剂的重要要求是它具有可接近的电子能级以接受电子。 这是合理的，因为氧化涉及反应物的电子损失。 本研究的主要目的是研究工作催化剂的电子结构，以确定电子接受水平的可用性与催化活性有关。这将通过进行原位XANE~S（x射线吸收近边光谱）来完成，该光谱探测费米能量以上的电子能级。这些测量将得到EXAFS（扩展X射线吸收精细结构）数据的支持，以提供催化剂的结构，这是解释XANES结果的重要要求。此外，在原位红外测量将进行检查，活性中间体的结构是相同的，所有的负载型催化剂上，所研究的系统是两个系列的钼和锰催化剂负载在SiO_2，Al_2O_3，TiO_2，ZrO_2，并将用于乙醇的氧化。 这些催化剂对于研究是理想的，因为它们分别是部分氧化催化剂和全氧化催化剂。 因此，它们的使用也将允许研究选择性与催化活性的关系。 这项研究是有意义的，因为它将产生基本信息的因素，控制催化氧化系统的活性。 这些信息可以推广到许多其他反应中，电子转移过程是重要的，也可以应用于催化剂的设计。 这项调查将为PI提供一项重要科学技术的培训，即同步辐射的使用。 预计这种互动也将导致美国和日本之间的学生交流。 合作将是互利的，因为合作者的专业知识互补，这将有助于双向交流思想，技能和技术。

9819369OyamaThis award provides funds to support a 12-month research visit by Dr. S. Ted Oyama, Department of Chemical Engineering, Virginia Polytechnic Institute and State University, for collaboration with Drs. Yasuhiro Iwasawa and Kiyotaka Asakura, Department of Chemistry, University of Tokyo, and Dr. Kazunori Domen, Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Japan. These collaborators will conduct investigations on the reactivity of oxide catalysts. The project involves examining the relationship between electronic structure and catalytic activity of oxide surfaces. Preliminary work indicates that in alcohol oxidation reactions there is a strong effect of supporting oxides of the catalysts that results in orders-of-magnitude difference in turnover rate, with little effect on the activation energy. This can be explained by a rate-determining step that involves electron transfer to the catalytic site. Thus, an important requirement for an effective catalyst is for it to have accessible electronic levels to accept electrons. This is reasonable because oxidation involves loss of electrons by the reactants. The principal objective of this study is to investigate the electronic structure of working catalysts to ascertain that the availability of electron-accepting levels is related to the catalytic activity. This will be done by carrying out in situ XANE~S (x-ray absorption near edge spectroscopy), which probes the electronic levels above the Fermi energy. These measurements will be supported by EXAFS (extended x-ray absorption fine structure) data to provide the structure of the catalysts, an important requirement for interpreting the XANES results. In addition, in situ infrared measurements will be carried out to check that the structure of the reactive intermediates is the same on all supported catalysts.The systems to be studied are two series of molybdenum and manganese catalysts supported on SiO2, Al203, TiO2, and ZrO2, and will be employed in the oxidation of ethanol. These catalysts are ideal for the investigation because they are, respectively, partial and total oxidation catalysts. Thus, their use will also allow study of the relationship of selectivity to catalytic activity. This research is significant because it will yield fundamental information about the factors that control catalytic activity in oxidation systems. The information can be extended to many other reactions in which electron transfer processes are important, and also can be applied to catalyst design. The investigation will provide the PI with training in an important scientific technique, the use of synchrotron radiation. It also is expected that the interaction will lead to the exchange of students between the U.S. and Japan. The collaboration will be mutually beneficial because of the complementary expertise of the collaborators which will contribute to the two-way exchanges of ideas, skills, and techniques.***