Abstract
The authors have so far demonstrated that production of fine TiO2 powder is possible by gas phase hydrolysis of titanium tetraisopropoxide (TTIP). In this paper, the effects are discussed of the shape of reactor and operational condition, such as mixing condition on the produced particle properties especially particle diameter of produced TiO2 fines.
Our originally designed reactor was used, in which the steam vapor was fed from the bottom of the reactor then transported through an internal thin tube in the heated part of the reactor, and then mixed with TTIP fed from the top of the reactor without heating. The TiO2 fines were produced by 1.00 ml/min of TTIP gas flow (RC I) at 200, 300, 400 and 500°C of the reactor temperature with 10.0 ml/min (at 25°C) of TTIP gas flow (RC II).
The particle diameter of TiO2 produced by gas phase synthesis was the smallest at 200°C, while the produced TiO2 showed increased crystallinity and photochemical activity with increased reaction temperature. The photocatalytic activity of TiO2 fines produced at 500°C was around 1/10, while that of the calcinated TiO2 fines produced at 200°C under RC II was 1/4 compared with that of JRC-TIO-4, respectively. The results of the photocatalytic activity tests suggested the activity is expected to be increased not only with increased crystallinities but also with decreased particle size.
