Oxydehydrogenation of cyclohexanol over carbon catalysts

The reaction of cyclohexanol over carbon catalysts with surfaces of different chemical nature was studied. The catalyst samples were prepared by treating a parent activated carbon with HNO3, H2O2, O-2 and N2O. The catalytic tests were performed in a packed-bed reactor at 350 degrees C. Dehydration as well as dehydrogenation of the substrate occur under the reaction conditions. The main products obtained are cyclohexene, cyclohexanone, benzene and phenol. Dehydration occurs preferentially over the carbon treated with HNO3, while the best selectivity to cyclohexanone is achieved with the carbon treated with H2O2. The catalyst sample treated with N2O is highly selective to phenol. A mechanism involving nitro groups on the carbon's surface is proposed. (C) 1998 Elsevier Science Ltd. All rights reserved.