Selective Hydrogenation of Phenol

Selective hydrogenation of phenol to cyclohexanone has attracted a great deal of attentions both in industry and academic field. Here in this review, the significances, strategies and mechanisms for the production of cyclohexanone are briefly described. Then, we mainly summarize the evolution of phenol hydrogenation in gas/liquid phase by the classification of catalyst types. In situ hydrogenation techniques including catalytic transfer hydrogenation (CTH) and electro-catalytic hydrogenation (ECH) of phenol are also discussed. Despite technology of catalyst design has been developed rapidly within the past decades, the direct evidences to understand the reaction mechanisms and kinetics are still scarce. Therefore, it is still of great challenge to 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.