The Design of Supported Metal Composite Oxides by Selective Metal-Support Exchange

这项工作的目标是系统地编写 负载在复合氧化物上的金属催化剂， 催化活性与催化剂性质的相关性 支持. 在水环境中，金属氧化物会产生 表面电荷;电荷为零时的pH值 称为“零电荷点”（PZC）。 纯二氧化硅的pzc 和纯氧化铝的分离约为4个单位。 选择性金属载体交换利用表面电荷， 将催化剂前体（金属盐）附着到载体上;因此 通过调节pH，可以选择性地引入阴离子或 阳离子催化剂前体。 此外，通过准备 二氧化硅和氧化铝的复合氧化物，原则上可以 至少，控制住pzc. 在这项研究中， 催化剂由阴离子和（分别地） 在一系列二氧化硅/氧化铝复合材料上的阳离子前体， 丁烯加氢催化剂的活性 和环丙烷氢解与 载体的组成和制备方法。 这项工作是一项努力，介绍科学原理， 负载型催化剂的制备方法;传统上 这些都是使用“食谱”准备的，这些食谱更多地代表了 艺术胜过科学 这项研究的设计方式是， 它可以作为一个“模板”，以获得设计数据， 各种系统。 所涉及的原则和方法是 适用于制备反应性陶瓷膜， 好.

The objective of this work is the systematic preparation of metal catalysts supported on composite oxides and the correlation of catalytic activity with the properties of the support. In an agueous environment, metal oxides develop a surface charge; the pH at which the charge in zero is defined as the "point of zero charge" (pzc). The pzc of pure silica and that of pure alumina are separated by about 4 units. Selective metal-support exchange uses the surface charge to attach catalyst precursors (metal salts) to the support; thus by adjusting the pH one can selectively introduce anionic or cationic catalyst precursors. Furthermore, by preparing composite oxides of silica and alumina, one can, in principle at least, control the pzc. In this study, supported cobalt catalysts are prepared from both anionic and (separately) cationic precursors on a series of silica/alumina composites, and the activities of the catalysts for butene hydrogenation and cyclopropane hydrogenolysis are correlated with the composition of the support and the method of preparation. This work is an effort to introduce scientific principles and methods into preparation of supported catalysts; traditionally these are prepared using "recipes" that represent more of an art than a science. The study is designed in such a way that it can serve as a "template" to obtain design data on a variety of systems. The principles and approches involved are applicable to preparation of reactive ceramic membranes as well.