New synthesis of pure Ce _x Zr_1−x O₂ mixed oxides (0 ≤ x ≤ 1) by an epoxide sol–gel method

Abstract

Pure ceria-zirconia mixed oxides Ce _x Zr_1−x O₂ with high specific surface area were synthesized with a new epoxyde driven sol–gel route and characterized by thermal analysis, X-ray diffraction studies and transmission electron microscopy. This sol–gel method is cheap and uses only a few steps. The Ce _x Zr_1−x O₂ mixed oxides were obtained in the range of 0 ≤ x ≤ 1 (except for x = 0.8) and crystallised at 350 °C after decomposition of the gels. This temperature is very low in comparison with the other methods. The studies of the influence of different synthesis parameters (concentration of the sol and decomposition temperature) allowed us to determine the conditions to obtain the best homogeneity in the gel to avoid the formation of a mixture of phases instead of mixed oxides. This approach leads to the synthesis of oxide with specific surface area above 100 m² g⁻¹. The elaboration of an ambigel could increase this value up to 195 m² g⁻¹ for x = 0.5. This sol–gel synthesis offers new perspectives for these oxides in several applications. Generally, these oxides are difficult to obtain pure in large range of composition at low-temperature and with high specific surface area by other methods.