Abstract: The Nb2O5/α-Al2O3 catalyst was prepared by impregnation method and used for ethylene oxide (EO) hydration to form ethylene glycol. The effects of the calcination temperature on the structure, acidity, and the catalytic performance of the catalyst were investigated by using X-ray diffraction, thermogravimetry and differential thermal analysis, infrared spectroscopy, temperature-programmed desorption of NH3, temperature-programmed desorption of EO, scanning electron microscopy, and transmission electron microscopy. It was found that the crystal form of niobium oxide, the catalyst acidity, and the EO adsorption strength were markedly influenced by the calcination temperature, which resulted in the dependence of EO conversion and ethylene glycol selectivity on the calcination temperature. The reaction results were discussed in terms of the strength and density of acidity resulted from the different structure formed at various calcination temperature.

Key words: niobium oxide, alumina, ethylene oxide, ethylene glycol, hydration, calcination temperature