Preparation Of Purity Titanium Dioxide Powder Through Gas Phase Hydrolysis In Fluidized Bed

Titanium dioxide is one kind of fine chemical products. Titanium dioxide has semiconducting properties and its dielectric constant and resistivity is high, so, it plays important roles in the technology fields such as catalysts and supports, cosmetics, ceramics and so on. Its application has different demands on product purity, impurity content, particle size, etc.This study prepared titanium dioxide particles through phase hydrolysis of titanium tetrachloride. A new chlorine removal technology was proposed in the present paper. The products were calcined under different atmosphere in the fluidized state, the effect of chlorine removal and on the particle morphology was compared. Ammonia gas was used to change the atmosphere of titanium tetrachloride hydrolysis reaction and the effect of chlorine removal was improved after calcination.The main points and results are as follows:(1) Establishment of titanium tetrachloride hydrolysis reaction system. Different fluidized beds were designed to get avoid yellow scabs block the airway and get a better gas contact. Product yield of fluidized deposition was studied. A filter was designed to collect the powders.(2) Effect of reaction conditions such as temperature molar ratio on product was studied. The particle size is smaller and the chlorine content of the product is lower when the reaction temperature is higher. Anatase peak becomes stronger under 600? and becomes weaker above 600? because of the transformation from anatase to rutile phase. Higher molar ratio help to reduce the chlorine content of the product. The products has a good sphericity when the reaction temperature under 400?.(3) Different after-treatment methods under various atmosphere was compared for chlorine removal. The effect of chlorine removal was H2>H2O>direct calcination. Calcined at higher temperature with water vapor is beneficial to crystal transformation. It contain miscellaneous peak after being calcined with H2 even after oxidation treatment.(4) Ammonia gas was used to change the atmosphere of titanium tetrachloride hydrolysis reaction. The powders chlorine content was significantly lower than hydrolysis without ammonia gas after calcination and the crystalline was difference. We can get lower chlorine content after calcination under lower temperature when titanium tetrachloride hydrolysis under ammonia gas.99.96% titanium dioxide was get when the temperature was 150? and calcined under 800? for two hour.