Amorphous Ni-B/gamma-Al2O3 catalyst prepared in a modified drying approachand its excellent activity in benzene hydrogenation

A two-step dying approach was proposed for the preparation of supported amo rphous Ni-B/gamma -Al2O3 catalyst. After wetness impregnation of NiCl2 aque ous solution, the catalyst precursor was dried at 343 K first, followed by drying at 383 K before KBH4 reduction (denoted as Ni-B/gamma -Al2O3 (LT)). For comparison, the precursor was directly dried at 383 K and reduced by KB H4 (denoted as Ni-B/gamma -Al2O3 (HT)). Liquid phase hydrogenation of benze ne to cyclohexane was employed as the probe reaction. While X-ray diffracti on (XRD), extended X-ray absorption fine structure (EXAFS), X-ray photoelec tron spectroscopy (XPS) and turnover frequency (TOF) revealed no considerab le electronic or structural difference between the active components of the se two catalysts, scanning electron micrography (SEM), H-2 chemisorption an d XPS intensity analysis demonstrated the higher dispersion of active compo nent in the Ni-B/gamma -Al2O3 catalyst prepared by the two-step drying appr oach, which can account for the superior catalytic performance of Ni-B/gamm a -Al2O3 (LT) to Ni-B/gamma -Al2O3 (HT) in benzene hydrogenation. (C) 2001 Elsevier Science B.V. All rights reserved.