Dynamic Structure of Graphite-Supported Iron-Iridium and Iron-Palladium Catalyst Particles

点击翻译按钮获取中文摘要

Earlier work on iron-rhodium bimetallic catalysts supported on carbon is extended to two additional systems: iron-iridium and iron-palladium. The previous study showed that varying the pretreatment conditions produced different surface states of the iron-rhodium bimetallic, ranging from isolated (separate) metals to an intimate alloy. Preliminary studies on iron-iridium indicate not only that the segregation effects occur in this system, but that it is possible to obtain catalysts with the high activity associated with iridium but displaying the strong selectivity associated with the much less active iron. In this study, iron-iridium and iron- palladium catalysts are studied using Mossbauer spectroscopy, X-ray diffraction, electron microscopy, calorimetry, and reaction probes. The initial reaction probe is 1-butene hydrogenation/isomerization. This work is exciting for its practical implications. Adoption of automotive emissions standards by the European Community has placed a great strain on the world supply of noble metals, and a major objective of much research is to develop means of controlling emission that do not rely on these very expensive and scarce materials. This approach does not eliminate the need for noble metals, but it greatly reduces the amounts required, perhaps by as much as 80%, replacing it with readily available iron. The work is also significant for insights into alloy formation and stability.