Determination of Metal-Oxygen Bond Strength in Oxide Catalysts

在这个项目中，涉及的金属-氧键的能量 氧化物的还原和再氧化通过 使用热流量热计的量热法。 还原热 测量通过一氧化碳或通过氢气的还原; 这允许计算金属的形成热， 氧键使用已知的小的 分子，或者，如果必要的话，测量再氧化的热量。 如果形成表面羟基，它们的生成热可以 也要坚决。 进行激光拉曼光谱分析 在量热法之前和之后，用于识别和 跟踪量热法中形成或断裂的特定键 反应. 最初的实验是在高度分散的 氧化钒负载或γ-氧化铝和氧化铝的相 （二氧化钛）。 没有关于金属-氧键能量的数据。 这些数据对于理解 氧化物的催化和表面化学，特别是 选择性催化氧化反应，其中表面 是氧气的最接近的来源;提出的努力是一个 艰巨的任务 选择性氧化是 生产各种商品和特产 化学品 虽然催化行为是这方面的重点 研究，结果也将有助于了解 半导体表面和绝缘层 结构材料的钝化和腐蚀 材料.

In this project, the energies of metal-oxygen bonds involved in reduction and reoxidation of an oxide are measured by calorimetry using a heat-flow calorimeter. Heats of reduction are measured for reduction by carbon monoxide or by hydrogen; this permits calculation of heats of formation for metal- oxygen bonds using the known heats of formation of small molecules, or, if necessary, the mesured heat of reoxidation. If surface hydroxyls are formed, their heats of formation can also be determined. Laser Raman spectroscopy, performed before and after the calorimetry, is used to identify and track the particular bonds made or broken in the calorimetric reactions. Initial experiments are on the highly dispersed phases of vanadia supported or gamma-alumina and anatase (titania). Data on the energies of metal-oxygen bonds are not available. Such data should be very useful for understanding the catalysis and surface chemistry of oxides, particularly selective catalytic oxidation reactions in which the surface is the proximate source of oxygen; the effort proposed is a formidable task. Selective oxidations are major elements in the production of a variety of commodity and specialty chemicals. Although catalytic behavior is the focus of this study, the results will also contribute to understanding semiconductor surfaces and insulating layers in electronic materials, and passivation an corrosion in structrual materials.