Der positive Promotor‐Effekt von Bund der negative Effekt von P in NiB‐ bzw. NiP‐Hydrierungskatalysatoren lassen sich durch den Einfluß von B und P auf die Elektronendichte im Ni erklären: B gibt Elektronen an das Ni ab, während P Elektronen aus dem Ni abzieht, was eine Zunahme der Aktivität mit steigendem B‐Gehalt und eine Abnahme der Aktivität mit steigendem P‐Gehalt der Katalysatoroberfläche zur Folge hat.
The surface state of the coprecipitated CuO-ZnO catalysts reduced at 250 "C with Hz was investigated by X-ray photoelectron spectroscopy (XPS). It was found that a monovalent copper species was present in the surface of the catalysts with low copper contents. It was revealed that two distinct types of copper metal species, both of them being negatively charged by electron transfer from ZnO, were produced in the catalyst surface upon the reduction. In the high copper content catalysts (>25 wt % CuO), the predominant Cu metal species is described by well-dispersed metal particles, whereas in the low copper content catalysts (
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