Abstract: Liquid phase hydroxylation of benzene to phenol with hydrogen peroxide over VO_x-TiO₂ catalyst samples with Cu as a second metal was investigated. A series of Cu/VO_x-TiO₂ (vanadium loading was 4.3%) catalysts were prepared within the range of Cu loading (0.29%–2.5%) and calcined at the temperatures of 350–650 °C. The catalyst samples were characterized by N₂ adsorption-desorption, scanning electron microscopy, H₂ temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. After the addition of Cu, the Cu/VO_x-TiO₂ catalyst had more ordered mesoporous structure as compared with the VO_x-TiO₂ catalyst, and the vanadium was monodispersed on the TiO₂ support. The presence of Cu²⁺ ions on the catalyst surface was shown by XPS measurements. These Cu²⁺ ions probably contributed to the dispersion of vanadium on the surface of the TiO₂ support, and the more facile reduction of VO_x. The Cu²⁺ ions also strengthened the thermostability of the Cu/VO_x-TiO₂ catalyst. The effects of some other variables (Cu loading, catalyst amount, and reaction temperature) on the catalytic performance were also investigated.

Key words: copper, vanadium species, mesoporous titania, benzene, hydroxylation, phenol