Selective Hydrogenation of Phenol

The selective hydrogenation of phenol to cyclo-hexanone has attracted a great deal of attention both in industry and academia. In this review, the significance, strategies and mechanisms for the production of cyclo-hexanone are briefly described. Then, the evolution of phenol hydrogenation in gas/liquid phase is summarized according to catalyst type. In situ hydrogenation techniques including catalytic transfer hydrogenation (CTH) and electrocatalytic hydrogenation (ECH) of phenol are also discussed. Although the technology for catalyst design has developed rapidly within the past decades, direct evidence to understand the reaction mechanisms and kinetics is still scarce. Therefore, it is still challengingto explore the function mechanisms and design advanced catalysts with high activity and high selectivity (>95%) for direct hydrogenation of phenol to cyclohexanone. This review may provide guidance for these attempts.