PRODUCTION METHOD OF TITANIUM DIOXIDE (TiO2) PHOTOCATALYST AND TiO2 PHOTOCATALYST PRODUCED BY THE SAME

• US 20090286676A1
• Filed: 05/19/2008
• Published: 11/19/2009
• Est. Priority Date: 05/15/2008
• Status: Active Grant

• Current Assignee: Kyungpook National University
• Original Assignee: Kyungpook National University Industry-Academic Cooperation (Kyungpook National University)
• Inventors: Kim, Wha Jung, Kim, Tae Jeong, Kim, Sun Woo
• Granted Patent: US 7,851,407 B2
• Time in Patent Office: Days
• US Class Current: 502/216
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 35/004 Photocatalysts
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/033 Using Hydrolysis
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/053 Producing by wet processes, e.g. hydrolysing titanium salts
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2002/77 by unit-cell parameters, atom positions or structure diagrams
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2002/85 by XPS, EDX or EDAX data
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/14 Pore volume
• CPC Class Codes: C01P 2006/16 Pore diameter
• CPC Class Codes: C01P 2006/17 Pore diameter distribution

Abstract

A method for producing a titanium dioxide photocatalyst is provided. The method uses a sol-gel process wherein acid and base catalysts are added in two separate steps. According to the method, a titanium dioxide photocatalyst with increased mesoporosity can be produced without the use of any particular additive. Further, an anatase structure is formed upon drying and is maintained even after high-temperature calcination. Further provided is a titanium dioxide photocatalyst produced by the method. Further provided is a titanium dioxide photocatalyst doped with sulfur and zirconium, which is produced by using the method. The doped titanium dioxide photocatalyst exhibits catalytic activity even under visible light and excellent surface characteristics to achieve improved photocatalytic activity.

Claims

1. A method for producing a titanium dioxide photocatalyst, the method comprising the steps of:

(1) adding a solution (“

Solution A”

) containing an acid, water and an organic solvent dropwise to a solution of a titanium alkoxide in an organic solvent with stirring until the pH of the resulting solution is adjusted to 0.5 to 2.0;

(2) reacting the mixed solution with stirring for 12 to 48 hours to form a sol;

(3) adding a basic aqueous solution dropwise at a rate of 0.05 to 0.5 ml/sec to the reaction solution with stirring until the pH of the resulting solution reaches 6.0 to 10.0 to convert the sol to a gel;

(4) drying the gel at 110°

C. for 12 hours, followed by pulverization to obtain a powder; and

(5) calcining the powder at 350 to 800°

C.

2. The method according to claim 1, further comprising the step of aging the gel for 2 to 5 hours and washing the aged gel after step (3).

3. The method according to claim 1, wherein, in step (1), Solution A is added in an amount such that the molar ratio of the titanium alkoxide to the water is between 1:

10 and 1;

30.

4. The method according to claim 1, wherein the titanium alkoxide is selected from the group consisting of tetraethyl orthotitanate, titanium tetraisopropoxide, tetrabutyl orthotitanate, and mixtures thereof.

5. The method according to claim 1, wherein the acid is selected from the group consisting of nitric acid, hydrochloric acid, phosphoric acid, acetic acid, formic acid, carbonic acid, sulfuric acid and mixtures thereof.

6. The method according to claim 1, wherein the organic solvent is a C₁-C₆ alcohol.

7. The method according to claim 1, wherein the base used in step (3) is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonia, amine and mixtures thereof.

8. The method according to claim 1, wherein step (1) further includes the sub-step of simultaneously adding an organic solution (“

Solution B”

) containing a metal source and a non-metal source and Solution A dropwise to dope the titanium dioxide photocatalyst with the metal and the non-metal.

9. The method according to claim 8, wherein the metal source is a zirconium source and the non-metal source is a sulfur source.

10. The method according to claim 9, wherein the zirconium source is selected from the group consisting of zirconium acetylacetonate, zirconium chloride, zirconyl chloride hydrate, and mixtures thereof.

11. The method according to claim 9, wherein the sulfur source is selected from the group consisting of thiourea, thioacetamide, sulfuric acid and mixtures thereof.

12. A titanium dioxide photocatalyst produced by the method according to claim 1.

13. The titanium dioxide photocatalyst according to claim 12, wherein the photocatalyst has an anatase crystal structure

14. A titanium dioxide photocatalyst doped with sulfur and zirconium.

15. The titanium dioxide photocatalyst according to claim 14, wherein the zirconium is doped in an amount of 0.5 to 6 parts by weight, based on 100 parts by weight of titanium dioxide.

16. The titanium dioxide photocatalyst according to claim 14, wherein the sulfur is doped in an amount of 0.1 to 1.5 parts by weight, based on 100 parts by weight of titanium dioxide.