Investigation on the structure evolution of rutile TiO2 during calcination of mixed-salt-treated metatitanic acid

Abstract

The calcination of metatitanic acid is the key process of rutile TiO2 production by sulfuric acid method, and the calcination quality affects the crystal morphology, particle size and particle size distribution, and finally pigment properties of rutile TiO2. Mixed salts treatment assisted calcination was an efficient process to solve the basic scientific problems of high calcination temperature and long calcination time. In this study, mixed ZnO-P2O5 treatment agent was adopted in calcinating metatitanic acid to produce rutile TiO2, and the mixed salt treated metatitanic acid was annealed at various temperatures so as to investigate the structure evolution. Characterizations of the as-prepared TiO2 samples were carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to investigate the function of ZnO and P2O5 during the metatitanic acid calcination process. The results demonstrate that the surface oxygen vacancies resulting from the substitution of Ti4+ with Zn2+ can promote the anatase–rutile transformation while chemically adsorbed phosphate can reduce the sintering degree of TiO2 particles, resulting in a uniform particle size distribution.