A structural analysis of W-Sb mixed oxide catalyst

An investigation on the structure of W-Sb mixed oxide catalyst, W₁₂Sb_xO_y (x = 1, 3, 5), is proposed. The W-Sb mixed oxide powders were prepared by the calcination of aqueous precursors, antimony tartrate and ammoniummetatungstate, and characterized with scanning electron microscope, X-ray diffractometer, and transmission electron microscope. At low content of Sb (x = 1), the W-Sb mixed oxide powder consisted of polyhedral particles, and their crystal structure was triclinic WO₃. At higher content (x = 3, 5), majority of the oxide powders were bar-shaped particles, consisting of triclinic WO₃ and tetragonal WO₃. With electron diffraction pattern and simulation, Sb incorporation into the cuboctahedral sites of perovskite-like WO₃ was proved and its effect on the phase transition from triclinic to tetragonal was discussed.