Heat-induced fast hydrolysis to produce rutile TiO2 nanoparticles in a capillary microreactor

Preparation of rutile TiO2 nanoparticles usually employs sulfate or organic titanium as titanium source, because the hydrolysis from low-cost TiCl4 encounters serious problems of controlling heat transfer and reaction proceeding. In this study, a capillary microreactor was used to intensify the heat transfer and hydrolysis of TiCl4 without introducing other chemicals. The hydrolysis was completed within 5 min and reaction proceeding was highly controllable. Effects of reaction conditions on nanoparticle qualities were assessed and optimized. Rutile TiO2 with a crystalline purity of 99.8 % was synthesized, and the particles were uniform in size with a diameter of 33 nm. Theoretical simulation of the heat transfer was conducted, indicating that the desired temperature was reached within 18 s. A throughput of as high as 2.39 kg/h could be achieved in a 2 mm capillary. The strategy is simple and straightforward for continuous production.