Hydroxylation of benzene to phenol on Fe/TiO2 catalysts loaded with different types of second metal

This paper investigated the liquid phase hydroxylation of benzene to phenol with hydrogen peroxide over Fe/TiO2-based catalysts. Various types of second metal (i.e., Ni, Co, Pd and Pt) were loaded together with Fe on the TiO2 support and the catalytic performance of the obtained catalysts was compared. It was found that the presence of the second metal can improve the phenol production of the typical Fe/TiO2 catalyst. The yield of phenol follows the order: Pt > Pd >> Co ≈ Ni. Various techniques (NH3-TPD, XRD, BET surface area, SEM-EDX and XRF) were employed to characterize the Fe/TiO2, FePt/TiO2 and FePd/TiO2 catalysts. The acid property of the catalyst was found to be influenced by the addition of the second metal. Finally the effects of some operating variables (reaction time, H2O2/benzene ratio and amount of ascorbic acid) on the catalytic performance were investigated.