A two-step precipitation route to CeO2 material with improved thermal stability and reduction property

Two series of CeO2 samples were prepared by two different synthetic routes: one was conventional precipitation route employing ammonia as reactant, and the other was a two-step precipitation procedure, using ammonium carbonate ((NH4)2CO3) as precipitant at the first step and ammonia as reagent at the second step. The precipitates and their decomposition processes were characterized by thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectra (XPS). The results show that the precipitate produced at the (NH)4CO3 precipitation step mainly consists of carbonate species, however, after the second precipitation step by ammonia, the carbonate species are replaced by hydroxyl species. By introducing the intermediate carbonate precipitation process, the nucleation rate of CeO2 can be controlled. X- ray diffraction (XRD) and transmission electron microscopy (TEM) results indicate that the grain size of the precipitate prepared by two-precipitation route is larger than that of the precipitate prepared by conventional route. CeO2 prepared by this two-precipitation route exhibits higher thermal stability and better reduction property than that obtained by traditional procedure. After the heat treatment at 900 °C for 3 h, the surface area and pore volume are 25 m2·g-1 and 0.11 cm·g-1, respectively.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology