Research On The Preparation Of Highly Ordered Mesoporous Mixed-Oxides By Means Of Hard-Template Nanocasting

Mixed-metal oxides such as perovskite-type (ABO3) and spinel-type (AB2O4) oxides have a better application in many fields e.g. catalysis, sensing and storage for their special lattice structures and variable composition elements. However, traditional peroskites are hardly applied in any fields for their low surface areas. In this paper, hard-template method which is always used to prepare mesoporous metal oxides was optimized and orderly mesoporous mixed-metal oxides with high surface areas were prepared through the optimized method. The effect of SBA-15hard-templates’ residues on the mesostructure and catalytic activity of mesoporous LaFeO3perovskite over methyl chloride oxidation was also investigated. Finally, some other mixed and single metal oxides were prepared through this optimized hard-template method.Specificalry, this thesis explored the optimum value of citric acid in sol-gel method which was always adopted to preparing perovskites, in order to reduce the effect of amount of citric acid before and after calcination on the hard-template method. The result shown that La:Fe:Citric=1:1:0.5may be the proper ratio. Then, three nanocasting methods were applied to improve the loading the mesopores, including simple-mixing, rotary-evaporation method and reflux method. The results indicated that reflux method was an efficient method. The effect of SBA-15residue in mesoporous LaFeO3on its mesostructure and property was also investigated over the oxidation of CH3C1. The results shown that mesostructure may collapse if the residue of Si was hardly few, but too much left of Si was also bad for its catalytic property. The mesoporous spinel-type mixed oxides-CuFe2O4was also prepared by hard-template method with reflux. Its catalytic property was tested over the oxidation of NH3. Finally, mesoporous LaCoO3, LaMnO3and Co3O4, CeO2, MnO2were also prepared successfully through this method.