The Synthesis Of The Nanoparticles And Mesoporous Of Cerium Oxide

The material field mesoscopic system in the range of macro-and micro-world had been known about little for a long time due to the limitations of the restrictions on means of researching. With the rapid development of the computer techniques ,various instruments were used in researching the microscopic fields emerged in .A series of unique properties of mesoscopic or mesostructured materials have been continuously unveiled differing forms not only the macroscopicbut also the single molecules. These discoveries have sequentially surged worldwide highlights of studies on mesoscopic system. At the aspect of synthesis of materials, the first artificial preparation of metal consisting of so-called nanocrystal by H.Gleiter in 1984 and the first synthesis of ordered mesostructured materials in 1992 using self-organized surfactant as templates evoked researchers' great interests in the study of nanomaterials and mesostructured materials. Owning these unique properties ,the nanoparticls and mesostructure as a research focus are becoming the tendence in the future.At the same time , due to their abundant chemical and physical properties and unique outer electronic structures ,the Cerium Oxides of transition metal oxide , was selected in this dissertation. We focused on synthesis of these materials with nanoparticals and mesostructure and their catalytic properties .The main contents of these dissertation are summarized as follows:1. Study on the preparation methods of nanoparticles of Cerium Oxides and their catalytic properties.Several methods have been developed to prepare nanosized Cerium Oxides, including:(1) A effective method for preparation of Cerium Oxide nanosized particles had been developed to combine Sol-gol methods with the quick homogeneous precipitation of the Urea .The polyethylene glycol was employed to prevent the nanoparticles aggregation . The effect of the different conditions for synthesis had been researched. Then the optimum condition at 350℃calcinating polyethylene glycol to gain the optimal nanoparticles, then the specific surface of the CeO₂ nanoparticles can reach to 180m² /g with the average nanoparticles size of 7.5 nm.(2) The absorptive capacity in Ultraziolet of the prepared CeO₂ nanoparticles had been studied in detail. The result showed that , the absorptive capacity in ultraviolet of the nanoparticles is superior to the common particles and the capacity is strong.2. Synthesis of mesostructured Cerium OxideCerium Oxide was templated to synthesized using small molecular glucose, ethylenediamine as co-template, Inorganic salt Magnesium as templation, and the influences of the synthesis conditions. The results can be summarized as the following paragraphs(which had never been studied).(1)The small molecular Glucose was employed as templation and ethylenediamine as co-templation to gain the Cerium Oxide mesoporous material by hydrothermal with various of Cerium source.(2)The mesostructured Cerium Oxide with cubic fluorite structure had been successfully synthesized by several experimental strategies with magnesium carbonate as templation. The specific surface area is high to 129m²/g and the average size of nanoparticles is 5.6 nm .In addition ,the magnesium chloride as one of the raw materials to prepare magnesium carbonate can be recycled after recrytallization from the final filtrate.