Influence of La precursors on structure and properties of CeO2-ZrO2-Al2O3 composite oxides
(1. School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
2. Research Institute of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract: Three La-doped CeO2-ZrO2-Al2O3 (CZA) composite oxide samples, namely, CZA-I, CZA-II and CZA-III, were prepared following a co-precipitation method in the presence of La2O3, La(NO3)3？6H2O and H[La(EDTA)]？16H2O precursors, respectively. When the precursor samples are sintered at 1000 °C, the as-prepared composite oxides mainly exhibit the CeO2-ZrO2 cubic fluorite phase, while the γ-Al2O3 and δ-Al2O3 phases appear when the precursor samples are subjected to sintering at 1100 and 1200 °C. CZA-III exhibits improved redox properties after high-temperature treatment compared with CZA-I and CZA-II. CZA-III presents the largest surface area of 97.46 m2/g among the three CZAs when the CZA-III precursor sample is sintered at 1000 °C. Furthermore, the corresponding oxygen storage capacity (OSC) is the largest with value of 400.27 μmol/g when CZA-III precursor sample is sintered at 1000 °C. Additionally, CZA-III exhibits the best thermal stability and the highest reduction temperature. However, by increasing the sintering temperature to 1200 °C, there is a dramatic decline in the properties of surface area and OSC. And a decrease for CZA-III in surface area by 58.94% and a decrease of the OSC value by 74.56% are observed.
Key words: La precursor; ceria-zirconia solid solution; composite oxide; texture structure; redox property