Highly selective hydrogenation of phenol and derivatives over Pd catalysts supported on SiO2 and γ-Al2O3 in aqueous media

Pd/Al2O3 and Pd/SiO2 catalysts containing Pd nanoparticles in the size range of 3-13 nm were prepared and investigated in direct selective hydrogenation of phenol to cyclohexanone. Catalysts with 3 nm Pd nanoparticles present highly active and promoted the selective formation of cyclohexanone under atmospheric pressure of hydrogen in aqueous media without additives. Conversion of 99% and a selectivity higher than 99% were achieved within 3 h at 333 K. The generality of Pd/Al2O3 catalyst with 3 nm Pd nanoparticles for this reaction was demonstrated by selective hydrogenation of other hydroxylated aromatic compounds with similar performance. (C) 2014 Published by Elsevier B.V.