The relationship between hydrolysis conditions and hydrous titania polymorphs obtained in a titanyl sulfate and sulfmic acid solu- tion was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM...The relationship between hydrolysis conditions and hydrous titania polymorphs obtained in a titanyl sulfate and sulfmic acid solu- tion was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution transmission electron micros- copy （HRTEM）. The results revealed that the feeding rate of the titanyl sulfate stock solution, the concentration of sulfi.Lric acid, and the seed dosage of mtile crystal could significantly affect the hydrolysis rate, thus influencing the titania crystal phase. Hydrous TiO2 in the form of rutile, anatase, or the mixture of both could be obtained in solutions of low titanium concentrations and 2.5wt% to 15wt% sulfuric acid at 100℃. When the hydrolysis rate of titanitma expressed by TiOa was more than or equal to 0.04 g/（L.min）, the hydrolysate was almost phase-pure anatase, while the main phase state was rutile when the hydrolysis rate was less than or equal to 0.01 g/（L.min）. With the hy- drolysis rate between 0.02 and 0.03 g/（L.min）, the hydrolysate contained almost equal magnitude ofrutile and anatase. It seems that although rutile phase is thermodynamically stable in very acidic solutions, anatase is a kinetically stable phase.展开更多
基金financially supported by a grant from the Ph.D. Programs Foundation of the Ministry of Education of China (No.20070610125)
文摘The relationship between hydrolysis conditions and hydrous titania polymorphs obtained in a titanyl sulfate and sulfmic acid solu- tion was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution transmission electron micros- copy （HRTEM）. The results revealed that the feeding rate of the titanyl sulfate stock solution, the concentration of sulfi.Lric acid, and the seed dosage of mtile crystal could significantly affect the hydrolysis rate, thus influencing the titania crystal phase. Hydrous TiO2 in the form of rutile, anatase, or the mixture of both could be obtained in solutions of low titanium concentrations and 2.5wt% to 15wt% sulfuric acid at 100℃. When the hydrolysis rate of titanitma expressed by TiOa was more than or equal to 0.04 g/（L.min）, the hydrolysate was almost phase-pure anatase, while the main phase state was rutile when the hydrolysis rate was less than or equal to 0.01 g/（L.min）. With the hy- drolysis rate between 0.02 and 0.03 g/（L.min）, the hydrolysate contained almost equal magnitude ofrutile and anatase. It seems that although rutile phase is thermodynamically stable in very acidic solutions, anatase is a kinetically stable phase.
