Abstract: A series of molybdic oxide/ceria (MoO₃/CeO₂) composite catalysts with different MoO₃ concentrations (0, 5wt%, 7.5wt%, 10wt%, 12.5wt%, 15wt% and 20wt%) were prepared by hydrolysis of ammonium molybdate and the supports of CeO₂ at 70℃. The crystal structure, the morphology and interaction between MoO₃ and CeO₂ on the surface of the prepared MoO₃/CeO₂ composite catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), respectively. The catalytic activities of the prepared catalysts were evaluated by the electrolysis sulfuric acid solution. Results show that the catalytic activity of MoO₃/CeO₂ composite catalysts are superior compared with that of pure CeO₂, and the optimal concentration of MoO₃ is12.5wt%. The MoO₃ content threshold value of composite catalysts is between 12.5wt% and 15wt%, and it is identified that the Mo-O-Ce bond forms at the interface of MoO₃ and CeO₂ in the composite catalysts. Moreover, more surface Mo-O-Ce bond over the MoO₃/CeO₂ composite catalysts will further benefit the improvement of the catalytic activity.

Key words: hydrothermal, molybdic oxide, ceria, composite, catalytic activity