| dc.description.abstract | Molybdenum and vanadium based multi-metal oxides, which was added with niobium (Nb), tellurium (Te), palladium (Pd), tantalum (Ta), and nickel (Ni) and so on, have been used as the catalyst for this reaction. In this study, all of the catalysts were prepared by a slurry method and heat treated at 450-600℃. These catalysts were characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The crystalline phases in these samples were M1 phase, M2 phase, MoO3, Mo3Nb2O11, TeMo5O16, Mo6V9O40, and Mo5O14-like structure. Using TiO2 as the support yielded a smaller particle size of multi-metal oxides, keep the multi-metal oxide particles high dispersion and prevent from sintering. The presences of M1 phase and M2 phase were found in Te-containing oxides. After washing Mo-V-Nb-Te oxides with H2O2 solution, the M2 phase was dissolved and active phases were obtained. The multi-metal oxides should prepare at lower pH value (pH< 3) to obtain more active phases, such as M1 phase and Mo5O14-like structures. The Mo-V-based oxides with tellurium, niobium, and TiO2 were prepared by a slurry method to cause the formation of different crystalline phases. By changing the preparation conditions, one can increase the crystalline phases of the oxides. | en_US |