Aqueous system for the improved hydrogenation of phenol and its derivatives

Abstract

The hydrogenation of phenol to cyclohexanol under mild conditions (∼340 K) was achieved over Raney Ni catalyst in the aqueous phase. The adsorption–desorption properties of the reactants (phenol and H₂) and the products (cyclohexanone and cyclohexanol) on the Raney Ni catalyst are different in the aqueous phase and the organic phase. The hydrogenation rate of phenol is improved because the Raney Ni catalyst adsorbs more H₂ and phenol in water than in methanol. Meanwhile, the higher uptakes of H₂ and the lower desorption rates for cyclohexanone on the Raney Ni catalyst in the aqueous system result in the further hydrogenation of cyclohexanone to cyclohexanol.