Abstract: VSb₃ mixed oxide catalyst samples for propane ammoxidation were prepared by a coprecipitation method with the vanadium starting materials treated with different amounts of oxalic acid in the preparation process. The VSb₃ mixed oxide catalyst prepared with vanadium starting materials treated with nitric acid and the catalyst without treatment were also prepared for comparison. The effects of the oxalic acid amount on the physicochemical properties of the VSb₃ mixed oxide catalyst were investigated by low-temperature N₂ adsorption, X-ray diffraction, X-ray photoelectron spectroscopy, and H₂ temperature-programmed reduction, and its catalytic performance for propane ammoxidation to acrylonitrile was tested. The results showed that the addition of oxalic acid in preparation process can keep V at a low valence, which generates a greater amount of SbVO₄ phase that is vital active sites for propane ammoxidation. In the catalyst prepared with the oxalic acid/V molar ratio of 3, more SbVO₄ phase can be formed, and Sb and V with suitable valence and appropriate concentration could disperse on the catalyst surface, resulting in better balance between oxidation and reduction capability. Therefore, both the conversion of propane and the selectivity for acrylonitrile can be obviously enhanced over the VSb₃ mixed oxide catalyst prepared by treating vanadium starting materials with oxalic acid.

Key words: propane, ammoxidation, acrylonitrile, antimony, vanadium, mixed oxide, oxalic acid, treatment