Sustainable synthesis of Pd/C-doped TiO2 catalyst for the Selective Phenol Hydrogenation

The catalytic activity and selectivity of noble metal-based catalysts supported on C-TiO₂ hybrid materials has been studied in the phenol hydrogenation reaction. Hybrid supports were prepared by solvothermal and slurry synthesis and the influence of texture and surface pH on the activity and selectivity was verified under eco-friendly experimental conditions such as aqueous phase, low H₂ pressure and low temperature. Preliminary results on Pd- based catalysts showed that the chemical nature (hydrophobic/hydrophilic) of the support direct the reaction mechanism either to cyclohexanol or to cyclohexanone. Selectivity to cyclohexanone is obtained on more polar C-TiO₂ supports, while catalyst becomes selective to cyclohexanol on hydrophobic C-TiO₂ hybrid materials. A mechanism explaining difference in selectivity is proposed. It can be concluded that product distribution during the selective phenol hydrogenation under eco-friendly conditions is easily controlled by controlling the functionalization of the hybrid support which can be extrapolated to the study of other types of hybrid materials as catalytic supports.