Kinetics and Mechanism of Catalytic Oxidation with Ozone

这项建议涉及使用一种新型氧化剂臭氧来破坏挥发性有机化合物(VOCs)，这种氧化剂在低VOC浓度下是经济的，具有良好的实际应用潜力。这些研究集中在催化中最重要的几个方面：分子水平上的机理研究，不均匀表面的处理，以及对氧化物中反应性来源的理解。该项目的更广泛影响涉及五个领域，包括1)高度相关性，2)科学方面的高级培训，3)招募少数群体，4)支持本科教育，5)广泛传播成果。这项工作的目的是获得关于催化反应中各个步骤的分子水平信息。所研究的催化剂将是负载型MnOx和VOx，它们是完全氧化和部分氧化的高活性催化剂。这些将通过激光拉曼光谱(LRS)、扩展X射线吸收精细结构(EXAFS)测量和从头计算分子轨道计算来表征，以提供原子配位、键长和振动频率等信息。具体的底物将是甲醇和丙酮，这两种都是常用的溶剂。机理研究将结合各种条件(分压、温度)下的速率测量、吸附中间体的LRS测量和理论计算。本工作的另一个目标是更好地了解催化氧化反应中反应活性增强的原因。将要研究的假设是，对于酒精氧化和臭氧分解，在反应的速率决定步骤中，催化位置接受电子的能力是否是活性的关键决定因素。这将使用近边X射线吸收精细结构(NEXAFS)测量来完成，这是获得金属中心未占据电子态密度的理想方法，因此，可以探索催化剂的电子接受性能。

This proposal deals with the destruction of volatile organic compounds (VOCs) using a novel oxidant, ozone, which is economic at low VOC concentrations and has good potential for practical applications. The research focuses on aspects of fundamental importance in catalysis: the study of mechanism at a molecular level, the treatment of nonuniform surfaces, and the understanding of the origin of reactivity in oxides. The broader impact of the project is addressed in five areas that include 1) high relevancy, 2) advanced training in science, 3) recruitment of minorities, 4) support of undergraduate education, and 5) broad dissemination of results. The aim of the work is to obtain molecular level information about the various steps in the catalytic reactions. The catalysts to be studied will be supported MnOx and VOx, which are highly active catalysts for complete and partial oxidation. These will be characterized by laser Raman spectroscopy (LRS), extended x-ray absorption fine structure (EXAFS) measurements, and ab initio molecular orbital calculations to provide information such as atomic coordination, bond lengths, and vibrational frequencies. The specific substrates will be methanol and acetone, which are commonly used solvents. The mechanism studies will combine rate measurements at a variety of conditions (partial pressure, temperature) together with LRS measurements of adsorbed intermediates and theoretical calculations. Another objective in the present work is to better understand the origin of reactivity enhancement in catalytic oxidation reactions. The hypothesis that will be investigated is whether for alcohol oxidation and ozone decomposition the ability of the catalytic site to accept electrons in the rate-determining step of the reaction is a key determinant of activity. This will be done using near-edge x-ray absorption fine structure (NEXAFS) measurements, which are ideal for obtaining the density of unoccupied electronic states in metal centers, and therefore, to probe the electron-accepting properties of the catalysts.