Using the purified TiCl4 from the chlorination titanium dioxide plant as the raw material, after diluting it to a certain concentration, adding alkaline solution for neutralization and hydrolysis, the nano-TiO2 product can be obtained after washing, drying and calcining the obtained TiO2 compound. The reaction formula is as follows:
TiCl4 + 4H2O === Ti (OH) 4 ↓ + 4HCl
Ti (OH) 4 === TiO2 + 2H2O
The neutralization method of TiOSO4 solution is to react pure metatitanic acid with sulfuric acid to produce pure TiOSO4 solution, and then prepare a certain concentration, then carry out hydrolysis in alkali or heat hydrolysis, and the formed titanium dioxide hydrate is depolymerized, washed and dried After the treatment, the amorphous nano-TiO2 product is obtained according to different calcination temperatures. The reaction formula is as follows:
Alkali neutralization hydrolysis method
TiOSO4 + 2NaOH + H2O === Ti (OH) 4 ↓ + Na2SO4
Ti (OH) 4 === TiO2 + 2H2O
Heating hydrolysis method
TiOSO4 + 2H2O === TiO (OH) 2 ↓ + H2SO4
TiO (OH) 2 === TiO2 + H2O
Is also called liquid precipitation method. That is, the intermediate product of the titanium dioxide plant of the sulfuric acid method titanium oxide sulfate is used as the raw material, and the industrial urea is used as the precipitant to generate the metatitanic acid precipitate, and then about 0.01mol / L of sulfuric acid and deionized water, as well as the sol and Sodium alkyl sulfonate is used as surfactant, and then flocculated and separated, spray-dried and calcined in rotary kiln to obtain nano-TiO2 particles. According to the different temperatures used in calcination, different crystal products can be obtained, of which the product obtained by calcination at 550 ℃ is anatase type, and the product obtained by calcination at more than 750 ℃ is rutile type. The particle size of TiO2 prepared by this method is 20-50mm. The yield is over 90%.
The method of Ishihara Industries Co., Ltd. is to neutralize the hydrolyzed metatitanic acid to pH 7 with ammonia, then filter and wash the branched sulfate radicals with water, then add hydrochloric acid to the filter cake to decoagulate and then adjust with ammonia To neutrality, then filter, wash with water, and calcinate at 400 ~ 700 ℃ for 2h to obtain 10 ~ 30nm nano-TiO2.
