Colloidal RuB/Al2O3•xH2O catalyst for liquid phase hydrogenation of benzene to cyclohexene

A colloidal RuB/Al-2-O-3.xH(2)O catalyst has been synthesized through a combined coprecipitation-crystallization-reduction strategy and characterized in detail with techniques including ICP-AES, N-2 physisorption, XRD, TG/DTA, PSD and TEM. The catalytic behavior in liquid phase selective hydrogenation of benzene to cyclohexene was studied and compared with that of the RuB/gamma.Al2O3 catalyst prepared by the incipient-wetness impregnation method. The RuB/Al2O3.xH(2)O catalyst is found more reactive than the RuB/gamma-Al2O3 catalyst, and the maximum yield of cyclohexene is about four times as high as that over the latter. The better activity of the colloidal catalyst is assigned to the higher dispersion of the smaller RuB particles, whereas its superior selectivity is attributed to the improved hydrophilicity due to higher content of structural water and surface hydroxyl groups. (C) 2004 Elsevier B.V. All rights reserved.