METHOD AND SOLUTION FOR FORMING ANATASE TITANIUM DIOXIDE, AND TITANIUM DIOXIDE PARTICLES, COLLOIDAL DISPERSION AND FILM

• US 20060254461A1
• Filed: 05/09/2006
• Published: 11/16/2006
• Est. Priority Date: 05/11/2005
• Status: Active Grant

• Current Assignee: Agency For Science Technology and Research
• Original Assignee: Agency For Science Technology and Research
• Inventors: Hong, Liang, Guo, Bing, Liu, Zhaolin, Jiang, Huixin
• Granted Patent: US 7,534,293 B2
• Time in Patent Office: Days
• US Class Current: 106/287.190
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 2531/46 Titanium
• CPC Class Codes: B01J 31/1815 with more than one complexing nitrogen atom, e.g. bipyridyl, 2-aminopyridine
• CPC Class Codes: B01J 31/226 Sulfur, e.g. thiocarbamates
• CPC Class Codes: B01J 31/38 of titanium, zirconium or hafnium
• CPC Class Codes: B01J 35/23 in a colloidal state
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/0211 using a colloidal suspension
• CPC Class Codes: B01J 37/0219 the coating containing organic compounds
• CPC Class Codes: B01J 37/033 Using Hydrolysis
• CPC Class Codes: C01G 23/053 Producing by wet processes, e.g. hydrolysing titanium salts

Abstract

A sol solution containing poly(titanic acid) and a planar heterocyclic ligand is provided. Titanium dioxide (TiO₂) particles are formed by aging the sol solution at a temperature below about 140° C. The particles have metallocene-like Ti-complexes comprising the heterocyclic ligand and can be substantially in the anatase phase. The heterocyclic ligands can be triazole, tetrazole, or thiadiazole. The sol solution may be prepared by aging a precursor solution. The precursor solution may contain the heterocyclic ligands and a precursor for poly(titanic acid). The precursor may be titanium alkoxide or titanium chloride. The sol solution may also contain at least one of an organic acid, a base, and a surfactant. The aged sol solution may form a colloidal dispersion of the TiO₂ particles. A photo-catalytic and transparent film may be formed from the TiO₂ particles by depositing a layer of the colloidal dispersion on a support.

Claims

1. A method of forming anatase titanium dioxide (TiO₂), comprising:

aging a sol solution comprising poly(titanic acid) and a planar heterocyclic ligand to form TiO₂ particles comprising a metallocene-like Ti-complex, said metallocene-like Ti-complex comprising said heterocyclic ligand.

2. The method of claim 1, wherein said aging a sol solution comprises aging said sol solution at a temperature below about 140°

C.

3. The method of claim 2, wherein said temperature is about 120°

C.

4. The method of claim 2, wherein said sol solution is aged for at least about 24 hours at said temperature, whereby said TiO₂ particles are substantially in an anatase phase.

5. The method of claim 1, wherein said heterocyclic ligand has less than 7 ring members.

6. The method of claim 1, wherein said heterocyclic ligand comprises at least one of triazole, tetrazole, and thiadiazole.

7. The method of claim 1, further comprising aging a precursor solution at a temperature from 80 to 100°

C. to form said sol solution, said precursor solution comprising said heterocyclic ligand and a precursor for said poly(titanic acid).

8. The method of claim 7, wherein said precursor solution is aged for at least about 24 hours at said temperature from 80 to 100°

C.

9. The method of claim 7, wherein said precursor for said poly(titanic acid) comprises at least one of titanium alkoxide and titanium chloride.

10. The method of claim 9, wherein said titanium alkoxide comprises at least one of titanium isopropoxide, titanium butoxide, and titanium ethoxide.

11. The method of claim 9, wherein said titanium chloride comprises titanium tetrachloride.

12. The method of claim 7, wherein said precursor is 5 to 20 wt % of said precursor solution.

13. The method of claim 12, wherein said precursor is 10 to 12 wt % of said precursor solution.

14. The method of claim 7, wherein said heterocyclic ligand is 0.1 to 1 wt % of said precursor solution.

15. The method of claim 14, wherein said heterocyclic ligand is 0.4 to 0.8 wt % of said precursor solution.

16. The method of claim 7, wherein said precursor solution further comprises an organic acid.

17. The method of claim 16, wherein said organic acid comprises at least one of an acetic acid, oxalic acid, lactic acid, citric acid, tartaric acid, succinic acid, α

,β

-hydroxycarboxylic acid, α

,β

-ketone,carboxylic acid, α

,β

-amino,carboxylic acid, and α

,β

-dihydroxy acid.

18. The method of claim 16, wherein said organic acid is 1 to 5 wt % of said precursor solution.

19. The method of claim 7, wherein said precursor solution further comprises a surfactant.

20. The method of claim 19, wherein said surfactant is selected from non-ionic and cationic surfactants.

21. The method of claim 19, wherein said surfactant comprises a poly(ethylene oxide) oligomer moiety.

22. The method of claim 19, wherein said surfactant is selected from alkyl, alkylarylethoxylate, polyoxyethylene alkyl ethers, and alkylbenzene sulphonate surfactants.

23. The method of claim 19, wherein said surfactant is 0.1 to 4 wt % of said precursor solution.

24. The method of claim 23, wherein said surfactant is 1 to 2 wt % of said precursor solution.

25. The method of claim 7, wherein said precursor solution further comprises a base.

26. The method of claim 25, wherein said base comprises an ethanolamine.

27. The method of claim 7, wherein said precursor solution has a pH value from 6 to 10.

28. The method of claim 7, wherein said sol solution has a solvent selected from water and alcohol.

29. The method of claim 1, wherein said TiO₂ particles have an average particle size from 5 to 20 nm.

30. Titanium dioxide (TiO₂) particles formed in accordance with claim 1, comprising said metallocene-like Ti-complex.

32. A method of forming a titanium dioxide (TiO₂) film, comprising depositing a layer of the TiO₂ particles of claim 30 on a support.

33. A film formed in accordance with the method of claim 32.

34. A film comprising the titanium dioxide particles of claim 30.

31. A colloidal dispersion of titanium dioxide (TiO₂) particles, said TiO₂ particles comprising a metallocene-like Ti-complex, said metallocene-like Ti-complex comprising a planar heterocyclic ligand.

35. A film comprising a titanium dioxide (TiO₂) matrix and a metallocene-like Ti-complex, said metallocene-like Ti-complex comprising a planar heterocyclic ligand.

36. A solution for forming a colloidal dispersion of anatase TiO₂ particles, comprising:

at least one of poly(titanic acid) and a precursor for poly(titanic acid); and

a planar heterocyclic ligand capable of forming a metallocene-like Ti-complex in a TiO₂ matrix.

37. A method of preparing the solution of claim 36, wherein said solution is a sol solution comprising said poly(titanic acid), said method comprising aging a solution comprising a precursor for poly(titanic acid) and a planar heterocyclic ligand, said planar heterocyclic ligand capable of forming a metallocene-like Ti-complex in a TiO₂ matrix.