Catalytic performance in phenol hydroxylation by hydrogen peroxide over a catalyst of V-Zr-O complex

The hydroxylation of phenol into catechol and hydroquinone with hydrogen peroxide has been carried out over a novel type of complex oxide H_xV₂Zr₂O₉H₂O with V⁴⁺ and V⁵⁺ mixed-valence. The catalytic activity depends on crystal size of the catalysts. The phenol conversion over the catalyst with crystal size of 7 μm is double that over catalyst with crystal size of 35 μm. The V⁵⁺ species are suggested to be the catalytic active sites. The reaction time, reaction temperature, the nature of the solvent, molar ratio of phenol to hydrogen peroxide, and amount of catalysts were found to be major factors for phenol conversion and product selectivity.