| 摘要 |
A process for the preparation of anatase titanium dioxide comprises precipitating hydrous titanium oxide from an aqueous solution of a titanium sulphate by heating said aqueous solution in the presence of a nuclei suspension consisting of non-rutilising nuclei said nuclei suspension being prepared in the substantial absence of aluminium ions, and subsequently subjecting the hydrous titanium oxide formed to a calcination process in the presence of at least one potassium compound, at least one phosphorus compound and at least one aluminium compound. The potassium compound is present in an amount equivalent to between 0.1 and 0.7 per cent by weight potassium oxide calculated as K2O with respect to TiO2, the phosphorus compound is present in an amount equivalent to between 0.2 and 1.0 per cent by weight phosphorus oxide calculated as P2O5 with respect to TiO2 and the aluminium compound is present in an amount equivalent to between 0.1 and 0.5 per cent by weight alumina calculated as Al2O3 with respect to TiO2 and in the calcination process the hydrous titanium oxide is converted to anatase titanium dioxide by heating to a temperature of at least 1000 DEG C. The anatase titanium dioxide formed has a large average crystal size in comparison to conventional anatase titanium dioxide. |
