Selective phenol hydrogenation in aqueous phase on Pd-based catalysts supported on hybrid TiO2-carbon materials

TiO2-C materials have been prepared by solvothermal and slurry synthesis and the influence of carbon properties upon the catalytic activity and selectivity of Pd-based catalysts on phenol hydrogenation in aqueous phase under mild reaction conditions has been studied. The nature of the catalysts can be modified to direct the reaction either to cyclohexanol (∼100% yield) or to cyclohexanone (∼96% yield). High selectivity to cyclohexanone is obtained with Pd on more polar TiO2-C supports, while when these are transformed into hydrophobic TiO2-C supports the resultant catalyst becomes selective to cyclohexanol. Thus, product distribution during the selective phenol hydrogenation in aqueous phase is easily controlled by controlling the functionalization of the hybrid support.