Hydrogenation of phenol to cyclohexanone over palladium and alkali-doped palladium catalysts

✍ Scribed by G. Neri; A.M. Visco; A. Donato; C. Milone; M. Malentacchi; G. Gubitosa

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 694 KB
• Volume: 110
• Category: Article
• ISSN: 0926-860X
• DOI: 10.1016/0926-860x(94)80104-5

✦ Synopsis

Palladium catalysts supported on A&O3 and MgO were prepared and used in the gas-phase hydrogenation of phenol to cyclohexanone. In all range of conditions investigated, selectivity to cyclohexanone was higher on Pd/MgO than on Pd/Al,03. On Pd/A1203 the reaction rates were found to be of first order with respect to the phenol partial pressure and second order with respect to the hydrogen pressure. On Pd/MgO, instead, the order of reaction with respect to phenol was -1 and the order with respect to hydrogen 'was about 1. Addition of alkali or alkaline earth metals (Ca, K, Cs) to Pd/A120, increased the activity and the selectivity to cyclohexanone without modifying the orders of reaction. On the basis of the results of this study, a reaction mechanism involving adsorption of phenol on the sites of the support at the interface of the palladium metal particles is proposed. The higher selectivity to cyclohexanone found on Pd/MgO compared to Pd/A120,, is explained by two different forms of adsorbed phenol.