SELECTIVE HYDROGENATION OF ACETOPHENONE ON CHROMIUM PROMOTED RANEY-NICKEL CATALYSTS .1. CHARACTERIZATION OF THE CATALYSTS

We prepared chromium promoted Raney nickel by two methods: catalysts of type I, by alkali leaching of Ni40-xCrxAl60 alloys (0.5 less-than-or-equal-to x less-than-or-equal-to 2.2) and by soaking the catalyst obtained from Ni40Al60 alloy in an aqueous chromium chloride solution, catalysts of type II. The structure of these catalysts was investigated by measuring the total and metallic surface area, by micro-analysis at fine scale with analytical transmission electron microscopy, X-ray diffraction and Auger spectroscopy. For all the catalysts the STEM/EDX analysis showed essentially two types of agglomerates, one of them being detected more frequently. This component presented itself very similar whether the dope was introduced by a metallurgical process or by a chemical way, but the more rarely observed agglomerates were different. From Auger spectroscopy it appeared that the surface Cr/Ni atomic ratios were higher in the catalysts of type II than in the catalysts of type I.