Abstract:The mechanism of scaling on the oxidation reactor wall in TiO2 synthesis process was investigated. The formation of wall scale is mostly due to being deposited and sintered of TiO2 particle formed in the gas phase reaction of TiCl4 with O2. The gas-phase oxidation of TiCl4 was in a high temperature tubular flow reactor with quartz and ceramic rods put in center respectively. Scale layers are formed on reactor wall and two rods. Morphology and phase composition of them were characterized by transmission electron microscope(TEM), scan electron micrographs(SEM) and X-ray diffraction(XRD). The state of reactor wall has a little effect on scaling formation. With uneven temperature distribution along axial of reactor, the higher the reaction temperature is，the thicker the scale layer and the more compact the scale structure is.

Key words: TiO2 synthesis; scaling; reactor wall; oxidation; chloride process