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

通过选择性金属载体交换设计负载型金属复合氧化物

• 批准号: 8900514
• 负责人: James Schwarz
• 金额: $ 14.1万
• 依托单位: Syracuse University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-09-01 至 1993-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8900514&HistoricalAwards=false
• 关键词: Design; Supported; Metal; Composite; Oxides

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.

本工作的目的是系统制备复合氧化物负载金属催化剂，并研究其催化活性与载体性质的关系。在水的环境中，金属氧化物产生表面电荷；零电荷的pH值被定义为“零电荷点”（pzc）。纯二氧化硅的pzc与纯氧化铝的pzc相差约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）附着在载体上；因此，通过调节pH值可以选择性地引入阴离子或阳离子催化剂前体。此外，通过制备二氧化硅和氧化铝的复合氧化物，至少在原则上可以控制pzc。在本研究中，负载型钴催化剂由阴离子和（分别）阳离子前驱体在一系列二氧化硅/氧化铝复合材料上制备。丁烯加氢和环丙烷氢解催化剂的活性与载体的组成和制备方法有关。这项工作是将科学原理和方法引入负载型催化剂的制备；传统上，这些都是用“食谱”准备的，与其说是一门科学，不如说是一门艺术。这项研究是这样设计的，它可以作为一个“模板”，以获得各种系统的设计数据。所涉及的原理和方法也适用于反应陶瓷膜的制备。