Selective Phenol Hydrogenation to Cyclohexanone Over a Dual Supported Pd-Lewis Acid Catalyst

• Published in: Science (American Association for the Advancement of Science) Vol. 326; no. 5957; pp. 1250 - 1252
• Main Authors: Liu, Huizhen, Jiang, Tao, Han, Buxing, Liang, Shuguang, Zhou, Yinxi
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Association for the Advancement of Science 27.11.2009; Amer Assoc Advancement Science; The American Association for the Advancement of Science
• Subjects: Acids; Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Chemistry; Exact sciences and technology; General and physical chemistry; Ion-exchange; Kinetics; Lewis acids; Liquid phases; Multidisciplinary Sciences; Nanoparticles; Phenols; Reactants; Science & Technology; Science & Technology - Other Topics; Solvents; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vapor phases; Water pressure; Zeolites; Zeolites: preparations and properties; VAPOR-PHASE HYDROGENATION; OXIDATION; BENZENE; LIQUID; ARENES; SILICA; CARBON-DIOXIDE; PALLADIUM CATALYSTS; Binary compound; Nylon; Hydrogen; Carbon dioxide; Alcohol; Selectivity; Hydrogenation; Molecular sieve; Supported catalyst; Chemical reduction; Synthesis; Cyclohexanone; Platinoid; Catalyst support; Lewis acid; Transition metal; Palladium; Zeolite; Carbon; Conversion; Ketone; Heterogeneous catalysis; Phenol; Pressure effect; Benzenic compound; Kinetics; Cyclohexanol; Alumina
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1179713

Cyclohexanone is an industrially important intermediate in the synthesis of materials such as nylon, but preparing it efficiently through direct hydrogenation of phenol is hindered by over-reduction to cyclohexanol. Here we report that a previously unappreciated combination of two common commercial catalysts[horizontal bar]nanoparticulate palladium (supported on carbon, alumina, or NaY zeolite) and a Lewis acid such as AlCl₃[horizontal bar]synergistically promotes this reaction. Conversion exceeding 99.9% was achieved with >99.9% selectivity within 7 hours at 1.0-megapascal hydrogen pressure and 50°C. The reaction was accelerated at higher temperature or in a compressed CO₂ solvent medium. Preliminary kinetic and spectroscopic studies suggest that the Lewis acid sequentially enhances the hydrogenation of phenol to cyclohexanone and then inhibits further hydrogenation of the ketone.