Continuous synthesis of TiO2 fine particles and increase of particle size using a two-stage slug flow tubular reactor

A novel continuous process has been developed, which consists of a two-stag e slug flow tubular reactor (SFTR) to increase the size of titanium dioxide fine particles. In a single-stage process, particle growth stops at a cert ain conversion level with unreacted titanium ethoxide remaining. In this pr ocess, however; water is added to the particle suspension containing unreac ted titanium ethoxide to allow the particle growth to proceed again. The pa rticles prepared using the two-stage SFTR process have a larger mean partic le size and smaller geometric standard deviation (GSD) than those from the single-stage process. The two-stage process also provides a higher conversi on to particles than the single-stage process does. A smaller amount of wat er fed into the first stage and a larger amount of water fed into the secon d stage results in a larger mean particle size, higher conversion to partic les, and smaller GSD. The width of the particle size distribution of the tw o-stage process is almost the same as that of the single-stage process. The calculated results using a mathematical model are in agreement with the ex perimental data.