Titania titanium compound reaction

Photocatalysis can be defined as follows A change in the rate of chemical reactions or their generation imder the action of light in the presence of substances called photocatalysts - that absorb light quanta and are involved in the chemical transformations of the reactants [4]. Typical photocatalysts or photosensitisers are semiconductor materials. There are many chemical compounds which can act as photocatalysts, but only a very few of these materials are photochemically and chemically stable semiconductor photocatalysts, one compound dominates titania (titanium dioxide) Ti02. 

One approach to making such powders is the sol-gel method, in which a metal oxide powder is synthesized from a metal alkoxide, a compound derived from a metal and an alcohol. In the synthesis of titania (Ti02) from titanium ethoxide, Ti(OCH2CH3)4, for example, the Ti(OCH2CH3)4 starting material is made by the reaction of titanium(IV) chloride with ethanol and ammonia in a benzene solution ... 

Photoreactions on titanium dioxide have been the focus of considerable interest for some time. Titania offers the opportunity to oxidize organic compounds in polluted environments, and has also been exploited to generate titania-supported nanoparticles of metals (e.g., silver) via photoreduction reactions [85]. While there is not enough room here to thoroughly treat photocatalytic processes, a brief introduction to the subject is presented below. Readers seeking detailed treatments of this subject are referred to a recent review by Yates etal. on titania-facilitated photocatalysis [86]. 

Besides alkoxides, acetylacetonates are also used as the starting materials for the synthesis of oxides. Titania (anatase) is obtained by decomposition of titanium oxyacetylacetonate (TiO(acac)2) in toluene at 300°C. Similarly solvothermal treatment of Fe(lll) acetylacetonate in toluene yields microcrystalline magnetite. One of the drawbacks of the use of acetylacetonate may be formation of various high boiling point organic by-products via aldol-type condensation of the acetylacetone. Actually more than 50 compounds are detected by gas chromatography-mass spectrometry (GC-MS) analysis of the supernatant of the reaction, some of which are phenolic compounds and are hardly removed from the oxide particles by washing with acetone. ... 

Evidence of spinel structure within some of the alumina and titania catalysts was established by x-ray powder techniques. Samples were removed from the reaction bed of some of the runs where high yields of sodium sulfate had been obtained using either alumina or titanium dioxide as catalyst. The presence of compounds having spinel type structure was established by x-ray powder diffraction. The amount of spinel was variable and of small quantity because neither the proportions of necessary ions nor the reaction conditions were ideal for spinel formation. 

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