Continuous synthesis of titanium dioxide fine particles using a slug flow ageing tube reactor

A continuous reactor system for titanium dioxide fine particle synthesis has been proposed, in which a packed bed for the nucleation of fine particles was connected in series with a slug flow ageing tube for growth of the particles. By injection of nitrogen gas into the inlet of the ageing tube, the continuous liquid feed was separated into small portions so that slug flow was formed. Spherical unagglomerated fine particles of titanium dioxide were obtained using this reactor system, and the effectiveness of using slug flow was elucidated. The effects of some operation variables such as liquid flow rate in the ageing tube and tube diameter were also examined. The particles obtained under the slug flow condition had narrower particle size distribution than those under a laminar flow condition at any flow rate. Particle geometric standard derivation (GSD) was found to be as small as that obtained in a batch process. No quality difference in particle GSD exists between ageing tubes of 2 mm i.d. and 3 mm i.d. for the slug flow. Chronomal analysis assuming diffusion-controlled growth was applied and was found to be effective for simulating a continuous particle synthesis process of titanium dioxide.