Effect of the tungsten precursor on the high activity of the WO3/ZrO2 catalyst in the oxidative lactonization of 1,2-benzenedimethanol Original Research Article

A series of tungsten oxide supported on commercial ZrO2 was synthesized via a traditional impregnation method using ammonium tungstate, phosphotungstic acid hydrate and tungstic acid–oxalic acid complex as the tungsten precursors. The supported catalysts were characterized by XRD, UV–vis DRS, Raman and XPS. It was found that the tungsten precursor and the calcination temperature were crucial to the dispersion and the nature of the tungsten species on ZrO2. The catalytic performances of the catalysts were investigated in the oxidative lactonization of 1,2-benzenedimethanol to phthalide with H2O2. The excellent catalytic performance of the catalyst prepared by calcination at 823 K after using tungstic acid-oxalic acid complex as the tungsten precursor was attributed to the presence of polymeric WO6 units.