Model Supported Metal Catalysts

制备了结构简单、高度分散的负载型金属催化剂，并进行了表征。催化剂是由金属有机前驱体在碱性载体(氧化镁和氧化镧)表面转化为具有特定结构的有机金属簇合物制备的；随后的脱羰反应得到与前驱体具有相同原子数的负载金属原子簇。这项研究中使用的金属是铱和铂。用红外光谱、扩展X射线吸附精细结构(EXAFS)和透射电子显微镜对样品进行了表征，并对烃类转化反应的催化活性和选择性进行了测定。这是对接近上限的分散(或者，相当于，小团簇中团簇大小的影响)对金属催化性能的影响的基础研究。对于为各种工业、能源和环境目的使用稀有金属催化剂的系统的优化来说，这个问题是一个关键问题。

Structurally simple, highly dispersed, supported metal catalysts are prepared and characterized. The catalysts are prepared from organometallic precursors which are converted into organometallic clusters of defined structures on the surfaces of basic supports (magnesia and lanthana); subsequent decarbonylation gives clusters of supported metal atoms with the same number of atoms as the precursors. The metals used in this study are iridium and platinum. Samples are characterized with infrared spectroscopy, extended X-ray adsorption fine structure (EXAFS), and transmission electron microscopy; catalytic activities and selectives are measured for hydrocarbon conversion reactions. This is a fundamental study of the effects of dispersion near the upper limit (or, equivalently, the effects of cluster size in small clusters) on the catalytic properties of metals. The issue is a critical one for the optimization of systems employing rare-metal catalysts for a variety of industry energy and environmental purposes.