Liquid phase hydroxylation of benzene over Cu-containing ternary hydrotalcites

Abstract

One step liquid phase hydroxylation of benzene to phenol over ternary hydrotalcites of general formula CuM(II)M(III)-HT, where M(II) = Mg, Co, Ni and Zn and M(III) = Al, Fe and Cr was carried out in the temperature range 30-80 degrees C using pyridine as solvent and H2O, as oxidant. Influence of various reaction parameters, such as reaction temperature, substrate: catalyst ratio, substrate weight, volume of the solvent, calcination temperature and reaction time were studied. Among the catalysts screened, CuCoAl-HT and CuNiAl-HT with (Cu + Co(or Ni))/Al = 3.0 and Cu/Co(or Ni) = 3.0 showed maximum activity with nearly 100% selectivity of phenol. The hydroxyl radical generated upon interaction of catalyst with oxidant is believed to be the active species involved in this reaction. (c) 2005 Elsevier B.V. All rights reserved.