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

In the present paper, we report on a novel procedure for preparing high performance Raney-Ni catalysts, which includes preparation of Ni–Al ribbons by melt-quenching, pretreatment with hydrogen and activation through Al leaching with sodium hydroxide solution. The resultant catalyst exhibits about five times high activity in the catalytic hydrogenation of cyclohexanone than that of the Raney-Ni catalyst obtained by a conventional preparation method. The structural variations of the catalyst caused by the different pretreatments were characterized by XRD, SEM and XPS. As demonstrated, melt-quenching and H2-pretreatment play a crucial role for forming the certain structure being composed of a high density of Ni2Al3 phase, which, in the subsequent leaching process, benefit to form ultra-uniform Raney-Ni catalyst with large surface areas. Metallic Al in hydrogen-pretreated alloys appears to be more easily leached, remaining aluminum as the dominant Al-related species on the surface, which acts as a matrix stabilizing the highly dispersed Ni and consequently improving the activity of cyclohexanone hydrogenation.