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In the water/triethanolamine/ethanol system, TiCl4 aqueous solution is used as the precursor to regulate the conversion rate of TiCl4 by changing the reaction temperature, water volume, pH value, and ethanol amount. The experiment uses a single-factor method to investigate the dynamic relationship between Ti4+ concentration and time under various factors, thereby achieving controllable TiO2 production. The experimental results showed that under a single factor, the conversion rate showed a trend of first steep and then slow growth within 180 min. After 180 min, the conversion rate tended to stabilize. Considering various factors, it was found that VTiCl4:VC6H15NO3:VH2O:VC2H5OH = 1:6:15:30, pH = 7, reaction time at room temperature was 4 h, and the hydrolysis effect was good. The final conversion rate was 90.46%, and the hydrolysis reaction conforms to the first-order reaction equation. Kinetic parameters: pre-factor (A) = 0.107, activation energy (Ea) = 4488.65 J mol-1.

The hydrolysis of Ti(IV)-bearing acid solution to prepare titanic acid particles is a crucial step for the production of TiO 2 material. The hydrolysis which takes place in HCl medium was investigated particularly with the purpose of preparing coarse particles with narrow size distributions for applications such as Ti metal powder production. The key factors that affect the hydrolysis ratio and rate, the morphology, and the size of the titanic acid particles were investigated. The results illustrated that temperature, initial free acid and equivalent TiO 2 concentrations cross-influence the above-mentioned key attributes of the product particles. Near spherical rutile particles with a D50 of around 30 μm were obtained under the optimal parameters. Four stages, including incubation, acceleration, near steady-state reaction, and deceleration, were observed during the progress of the hydrolysis reaction, while the precipitate morphology evolved from irregular to smooth, and to round as a result of the nucleus agglomeration. [Display omitted] • Micron-sized and near spherical TiO 2 powder is prepared via hydrolysis. • Initial free acid and equivalent TiO 2 concentrations cross-influence the size and morphology. • A sigmoid shape of yield vs. time illustrates the progression of hydrolysis with four stages. [ABSTRACT FROM AUTHOR]

Photocatalytic mesoporous titania–silica systems were prepared by the hydrolysis of titanium tetrachloride in aqueous dispersions of fine silica. IR spectroscopy was used to show the formation of ≡ Si—O—Ti ≡ bonds in theTiO 2–SiO 2 composites. Structure and adsorption techniques were used to establish that the size of the primary fine silica particles determines the crystal structure of titanium dioxide in the composites as well as the porous structure and photochemical properties of the composites. [ABSTRACT FROM AUTHOR]

Nanocrystalline perovskite barium titanate with an average particle size less than ∼10 nm is produced using sol-gel route involving ligand-assisted templating. BaTiO3 is obtained by the controlled hydrolysis and condensation reaction of barium acetate (Ba(CH3COO)2) with titanium tetra chloride (TiCl4) in the reverse micelles of dodecylamine (DDA) which is used as the template. Our attempts to produce mesoporous BaTiO3 have resulted in the formation of nanocrystalline BaTiO3. The synthesis of nanostructured BaTiO3 is carried out using the ligand-assisted templating approach which proceeds through the sol-gel route. Dodecylamine is used as the template. The sol-gel process in general presents inherent advantages because the nanostructure of the desired materials can be controlled together with their porous structure. Ligand-assisted templating approach involves the formation of covalent bond between the inorganic analogue and the template. Ba(CH3COO)2 and TiCl4 are used as barium-source and titanium-source respectively. The reaction between Ba(CH3COO)2 and TiCl4 is found to take place deliberately on the preassembled species which acts as the template or occurring with in them which in turn will lead to the generation of the desired nanoscale structure (nanopores or nanoparticles). [ABSTRACT FROM AUTHOR]

Nanocrystalline perovskite barium titanate with an average particle size less than ∼10 nm is produced using sol-gel route involving ligand-assisted templating. BaTiO3 is obtained by the controlled hydrolysis and condensation reaction of barium acetate (Ba(CH3COO)2) with titanium tetra chloride (TiCl4) in the reverse micelles of dodecylamine (DDA) which is used as the template. Our attempts to produce mesoporous BaTiO3 have resulted in the formation of nanocrystalline BaTiO3. The synthesis of nanostructured BaTiO3 is carried out using the ligand-assisted templating approach which proceeds through the sol-gel route. Dodecylamine is used as the template. The sol-gel process in general presents inherent advantages because the nanostructure of the desired materials can be controlled together with their porous structure. Ligand-assisted templating approach involves the formation of covalent bond between the inorganic analogue and the template. Ba(CH3COO)2 and TiCl4 are used as barium-source and titanium-source respectively. The reaction between Ba(CH3COO)2 and TiCl4 is found to take place deliberately on the preassembled species which acts as the template or occurring with in them which in turn will lead to the generation of the desired nanoscale structure (nanopores or nanoparticles). [ABSTRACT FROM AUTHOR]

Abstract: Nanosized TiO2 particles with a size of about 5–20nm and the specific surface area of about 188.5m2 g−1, in which two polymorphs of TiO2, brookite and rutile, are present, were obtained by heating aqueous TiCl4 solution with not more than 1.0M of Ti4+ at 80–150°C for 15h. The volume fraction of brookite in TiO2 particles was about 60–70% at 0.1–0.5M Ti4+, about 80–81% at 0.6–0.8M Ti4+ and about 69% at 1.0M Ti4+, respectively. The molar ratio of to Ti4+ for brookite formation ranged between 6.4 and 33. Reaction temperature, reaction time and HCl concentration in the solution are the decisive factors in determining phase content in TiO2 particles. Brookite in the mixture phase was directly transformed to rutile with increase in reaction time after complete oxidation of Ti4+ to TiO2 whereas it to rutile via anatase through heat treatment. [Copyright &y& Elsevier]