Preparation of rutile TiO2 by hydrolysis of TiOCl2 solution: experiment and theory

摘要

Titanium slag with a perovskite phase (CaTiO3) is difficult to use in traditional titanium dioxide production. Herein, we demonstrate that HCl can decompose CaTiO3 with a high acidolysis ratio of >97 wt% to obtain a TiOCl2 solution. With subsequent hydrolysis and calcination, rutile TiO2 was synthesised in one step without crystalline-structure transformation. As hydrolysis of the TiOCl2 solution to prepare metatitanic acid (H2TiO3) is an essential step in the process, a simulated pure TiOCl2 solution (prepared from TiCl4 and H2O) was confirmed to have the same structure in water as HCl-treated CaTiO3 slag by Raman spectroscopy. The TiOCl2 solution was also concluded to have the Ti compound cluster of (Ti2O2)(H2O)(4)Cl-4, based on DFT calculations from the Raman data and the curve fit for the hydrolysis ratio. By elucidating the relationship between the H2TiO3 particle size and the concentration of Ti4+ and HCl, we identified the nuclear energy as -19.46 kJ mol(-1). Moreover, a complete scheme for the production of rutile TiO2, induced by TiOCl2 solution hydrolysis, was proposed. Periodic structures show the feasibility of the following transformation occurring through a simple structural rearrangement: (Ti2O2)(H2O)(4)Cl-4 (in solution)-Ti(OH)(H2O)(2)Cl-3 (with addition of HCl)-Ti(OH)(2)Cl-2 (1-dimentional growth and removal of HCl)-rutile-type Ti(OH)(2)Cl-2 (stack)-rutile TiO2 (with removal of HCl).