Hydrogenation of cyclohexanone on nickel-tungsten sulfide catalysts

Unsupported Ni-W sulfide catalysts were tested for cyclohexanone hydrogenat ion under atmospheric pressure conditions and showed a high selectivity tow ards cyclohexene. They were prepared employing ammonium thiotungstate compl exes and nickel nitrate as metal-sulfide precursors. The data of catalytic activity show a synergetic effect as a function of stoichiometric compositi on, R = Ni/(Ni + W). A maximum synergetic effect occurred at R = 0.7. The t exture and surface composition characterization of the catalysts were carri ed out by BET surface area measurements, AES and XPS. The surface of cataly sts was found to be nickel deficient, compared to the nominal values, as de termined by AES and XPS. The electronic state of Ni changed as the catalyst stoichiometry varied, but the electronic state of W did not change. (C) 20 01 Elsevier Science B.V. All rights reserved.