| Aluminum isopropoxide (AIP) is an important precursor of ceramic materials, phosphors, high purity alumina nanomaterials, functional membranes and so on. In newly found factories, aluminum alkoxide is used as starting material to prepare high purity and ultrafine alumina via Sol-Gel technique. However, the biggest problem restricting the utilization of aluminum alkoxide is the high impurity content in products, such as iron, silicon, and magnesium, especially the iron impurity. According to the reported references and the relevant theories, iron can not react with isopropanol. However, it was definitely found that the low boiling-point iron-containing compounds were distilled accompanied with AIP, which means that iron impurity in Al can take part in the reaction. Though Dobizha E. V. reported this phenomenon in 1981, it did not draw further attention. With the aim to elucidate the control regulation of iron impurity in aluminum alkoxide and obtain high purity aluminum alkoxide as well as downstream products, the reaction conditions of iron impurity and isopropanol were investigated firstly. In addition, plausible formation mechanism of iron-containing compound was presumed. On the basis of above results, separation method and technology process of iron-containing compound in the synthesis system of AIP were studied. Furthermore, alumina-based luminescent materials excited by Europium were prepared using aluminum alkoxide as starting materials. The luminescence effect on phosphors arising from iron impurity was studied in this paper. The contents and results in this dissertation are listed below:1. The reaction conditions and regulation of iron impurity in Al with isopropanol were studied by changing the factors, such as different iron content of Al, reaction atmosphere, catalyst, morphological iron, etc. The function of isopropanol and AIP on the formation of this compound was also investigated. ICP-AES and UV-Vis adsorption spectra were used to characterize the products. It is found that, AIP and isopropanol are the necessary condition for formation of this compound. Oxygen can enhance the formation of it and Al can inhibit the formation of it. It was proved that there are two kinds of iron valence state (ferrous and ferric) in the system of preparing AIP, which can mutual conversion by the action of oxygen and metal iron. 2. A possible mechanism for the formation of iron-containing compound in the system of AIP-isopropanol was presumed. The obtained products were characterized by the means of EDTA titration method,1H NMR, elemental analysis, IR and XPS. According to the present results and electrochemical relevant theories, a plausible mechanism for the reaction of iron with isopropanol in the system of AIP-isopropanol was proposed. It is consisted of three consecutive steps, namely:small size iron particle created by Al reacting with isopropanol have high reactivity and can react with isorpopanol forming ferrous compound. The ferrous compound is immediately oxygenated to ferric compound, and then the ferric compound can be reduced to the ferrous compound in the presence of AIP and isopropanol. The above redox procedure is carried out cycling constantly.3. According to the above possible mechanism and the characteristics of iron compound, the separation of iron-containing compound from AIP was studied by exploring "chelate-distillation" and "adsorption-distillation" methods which are effective for removing trace iron from AIP. The effect of rectification on the purification of AIP was further investigated. ICP-AES and UV-Vis adsorption spectra were used to characterize the products. It is found that, O-containing chelating agent——Ligand-O is an effective chelating agent for removing trace iron from AIP with "chelate-distillation" method. Small size iron particles created by Al reacting with isopropanol are agglomerated by sorbent (S) to reduce the reaction activity with the aim of puritification. Although the rectification has good effect on the purification of AIP, it requires expensive equipment and high energy consumption.4. Eu3+-dopedγ-Al2O3 phosphor was prepared from aluminum alkoxide via hydrothermal assisted Sol-Gel method,γ,δ,α-Al2O3 hollow microspheres andγ-Al2O3:Eu3+ phosphor with hollow spherical structure were prepared from aluminum alkoxide using carbon microspheres prepared from hydrothermal method of glucose solution as templates. The forming process, structure, morphology and luminescent properties of the obtained products were characterized by means of TG, XRD, TEM, SEM and fluorescence spectrophotometer. The luminescence effect onγ-Al2O3:Eu3+ phosphor and hollow spheres ofγ-Al2O3:Eu3+ phosphor arising from iron impurity was studied in this part. The results indicate that theγ-Al2O3:Eu3+ phosphor shows pure cube phase. Luminescence test indicated that theγ-Al2O3:Eu3+ phosphor emits an intense characteristic luminescence of Eu3+ ions. The results revealed that iron impurity cause the quenching for luminescence ofγ-Al2O3:Eu3+ phosphors. The as-preparedγ-,δ-andα-alumina hollow microspheres with smooth surface show well-defined spherical morphology and narrow size-distribution. The obtainedγ-Al2O3:Eu3+ phosphor with hollow spherical structure shows pure cube phase. Luminescence test indicated that it emits an intense characteristic luminescence of Eu3+ ions. The results reveal that iron impurity cause the quenching of luminescence ofγ-Al2O3:Eu3+ phosphors with hollow sphereical structure as well.
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