Method of making rutile titanium dioxide microspheres containing elongated TiO2-nanocrystallites
AssigneeCristal Inorganic Chemicals Switzerland Ltd
InventorsGuoyi Fu, Mark B Watson
Life of this patent
Estimating the term…
Abstract
Rutile TiO2 microspheres and microparticles in a botryoidal morphology which form from ordered acicular aggregates of elongated TiO2 crystallites that resemble nano-sized flower bouquets and/or triangular funnels, and process for their preparation by thermally hydrolyzing a soluble TiO2 precursor compound in aqueous solution in the presence of a morphology controlling agent selected from carboxylic acids and amino acids.
Claims7
A method for preparing rutile TiO2 particles which comprise generally spherical structures in the range of from 1 to 2 microns in diameter, said structures being aggregates of elongated TiO2 crystallites, said method comprising:
- (a) forming an aqueous solution of a soluble titanium compound at a titanium concentration of from 0.5 to 1.0 moles per liter;
- (b) introducing a morphology controlling agent selected from the group consisting of an α-hydroxy carboxylic acid of the formula R—CH(OH)COOH, an α-hydroxy carboxamide of the formula R—CH(OH)CONH2 or an α-amino acid of the formula R—CH(NH2)COOH, wherein R is an alkane, alkene, alkyne, arene, or cycloalkane group having 4 or fewer carbon atoms, into the solution at an acid- or carboxamide-to-titanium molar ratio of from 0.02 to 0.2 while simultaneously heating the solution to a temperature in the range of from 75° C. to 80° C. with constant stirring;
- (c) maintaining the stirred solution at a temperature in the range of from 75° C. to 80° C. for a period of from one to 3 hours;
- (d) elevating the temperature of the stirred solution to a value of from 100° C. to the refluxing temperature and maintaining said temperature for a period of from 2 hours to 4 hours to form a reaction product;
- (e) optionally neutralizing the stirred solution which results from step (d);
- (f) cooling the stirred solution to room or ambient temperature;
- and
- (h) separating and drying the reaction product.
Dependencies are inferred from the claim text.