| Perovskite-type oxides have attracted particularly attentions from people for their use as new materials in environmental protection and energy resource. The structure and properties of these materials are strongly influenced by the synthesis process so it is very important to improve the preparation methods. In order to promote the research on theory and application of perovskite, the preparation of perovskite-type oxides by EDTA sol-gel method is systemically studied to improve the method and its stability and repeatability in this thesis.Perovskite-type oxides La1-xSrxFe1-yCoy03 were synthesized by EDTA complexing sol-gel method. The process and the samples were characterized via X-ray diffraction (XRD), transmission electron microscope (TEM), scan electron microscope (SEM), the specific surface area mensuration, thermo gravimetric analysis (TG) and differential thermal analysis (DTA), temperature-programmed desorption of O2 (O2-TPD) techniques and laser granularity analysis. The effects of different conditions, such as the system compositions, pH value, the amount of chelant, the amount of glycol, the evaporation temperature and the calcination temperature, were investigated in the process. And the catalysis of the sample in Zhaotong lignite combustion was studied through TG-DTA technique in brief. The optimum conditions of the preparation process have been chosen.Two series of perovskite-type oxides La1-xSrxFeO3 (x 0.8 ) and La1-xSrxFe1-yCoyO3 (x=0.2; y=0.2, 0.4) powder samples have been synthesized. The XRD results show that all the powder samples are perovskite-type compounds and no simple metal oxides or any other secondary phase exits. The lattice symmetry of La1-xSrxFe03 system changes from orthorhombic to rhombohedral lattice. La1-xSrxFe1-yCoy03 system has rhombohedral lattice. With the increase of x, the main diffraction peaks of XRD move to large angles, which represent a distortion to small size of the cell. TEM observation shows the powders are uniform with spherical shape. The average size is about 61 nm in diameter. Through SEM the powder can be identified to porous structure, with specific surface areas of about 11.6m2/g, total pore volume of 0.034cc/g and average pore diameter of 1 1 .9nm by BET method. The particle is uniform with an average size of about 0.1 8m by laser granularity analysis. The thermal decomposition process has been studied by TG-DTA technique. Smooth TG curves were obtained at about 620 C, indicating the formation of perovskite structure. Oxygen desorption from La1-xSrxFeO3 below 850 C was examined by O2-TPD and the result shows that there are three types of oxygen in the structure. According to TG-DTA results, the samples show little catalysis to Zhao tong lignite combustion, mainly because the samples didn't mixed with the lignite uniformly and at the same time there was excessive oxygen in experimental atmosphere leading to without obvious catalysis effect.The optimum conditions of the process are summarized as: the pH value of the solution should be adjusted to 7~14; the mol ratio of metal ion to EDTA should be 1:1.1 to 1:1.2; the mol ratio of glycol to EDTA is 3:1; the concentration temperature should be 60 C~70 C; calcination temperature should be 700 C~800 C. In conclusion, we can obtain single-phased, uniform perovskite-type oxides powder with small particle size by EDTA complexing sol-gel process with high stability and repeatability.
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