Preparation of novel Raney-Ni catalysts and characterization by XRD, SEM and XPS

In the present paper, we report on a novel procedure for preparing high per formance Raney-Ni catalysts, which includes preparation of NI-AI ribbons by melt-quenching. pretreatment with hydrogen and activation through Al leach ing with sodium hydroxide solution. The resultant catalyst exhibits about f ive times high activity in the catalytic hydrogenation of cyclohexanone tha n that of the Raney-Ni catalyst obtained by a conventional preparation meth od. The structural variations of the catalyst caused by the different pretr eatments were characterized by XRD. SEM and XPS. As demonstrated, melt-quen ching and H-2-pretreatment play a crucial role for forming the certain stru cture being composed of a high density of Ni2Al3 phase. which, in the subse quent leaching process. benefit to form ultra-uniform Raney-Ni catalyst wit h large surface areas. Metallic Al in hydrogen-pretreated alloys appears to be more easily leached, remaining aluminum as the dominant Al-related spec ies on the surface, which acts as a matrix stabilizing the highly dispersed Ni and consequently improving the activity of cyclohexanone hydrogenation. (C) 2001 Elsevier Science B.V. All rights reserved.