Synthesis, characterization, and catalytic phenol hydroxylation of a novel complex oxide HxV2Zr2O9.H2O

A novel type of complex oxide HxV2Zr2O9.H 2O with V4+ and V5+ mixed valence has been hydrothermally synthesized in a V2O5-ZrO2-H2O system at 240°C for 5 days in presence of NaF. The catalytic data over these complex oxides show that these complex oxides are catalytically very active in phenol hydroxylation by 30% aqueous hydrogen peroxide, and their catalytic activity is dependent on crystal size of the catalysts. The phenol conversion over the catalyst with crystal size of 7 μm is twice that over the catalyst with crystal size of 35 μm. The V5+ species are suggested to be the catalytic active sites. Some other factors which influence the catalytic activity were also investigated.