Titanate photocatalyst

• US 8,551,906 B2
• Filed: 08/15/2008
• Issued: 10/08/2013
• Est. Priority Date: 08/16/2007
• Status: Expired due to Fees

• Current Assignee: The University of Queensland
• Original Assignee: The University of Queensland
• Inventors: Lu, Gao Qing, Wang, Lianzhou
• Primary Examiner(s): Hailey, Patricia L
• Application Number:
  US12/673,693
• Publication Number:
  US 20110130272A1
• Time in Patent Office: 1,880 Days
• Field of Search: 502/200, 502/202, 502/208, 502/216, 502/350, 423/610, 423/659
• US Class Current: 502/200
• CPC Class Codes: B01D 2255/20707 Titanium
• CPC Class Codes: B01D 2255/802 Photocatalytic
• CPC Class Codes: B01D 53/885 Devices in general for catalytic purification of waste gases
• CPC Class Codes: B01J 23/002 Mixed oxides other than spinels, e.g. perovskite
• CPC Class Codes: B01J 23/04 Alkali metals
• CPC Class Codes: B01J 2523/00 Constitutive chemical elements of heterogeneous catalysts
• CPC Class Codes: B01J 2523/15 Caesium
• CPC Class Codes: B01J 2523/47 Titanium
• CPC Class Codes: B01J 27/24 Nitrogen compounds
• CPC Class Codes: B01J 35/39 Photocatalytic properties
• CPC Class Codes: B01J 37/08 Heat treatment B01J37/0009, B01J37/0018 take precedence
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01G 23/005 Alkali titanates
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C02F 1/32 with ultraviolet light
• CPC Class Codes: C02F 2305/10 Photocatalysts

Abstract

The invention relates to a titanate photocatalyst of formula (I): H_mA_x-mTi_yO_zD_n (I) wherein: A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium; D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine; x is a value between 0 and 8; y is a value greater than 0 and less than or equal to 8; n is a value greater than 0 and less than or equal to 8; z is a value greater than 0 and less than or equal to 8; and m is a value between 0 and 8. The invention also relates to method of production and uses of the titanate photocatalyst.

Claims

1. A titanate photocatalyst of formula (I):

H_mA_x-mTi_yO_zD_n 

 

(I)

wherein;

A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium;

D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine;

x is a value greater than 0 and less than or equal to 8;

y is a value greater than 0 and less than or equal to 8;

n is a value greater than 0 and less than or equal to 8;

z is a value greater than 0 and less than or equal to 8;

m is a value greater than 0 and less than or equal to 8; and

x-m is a value equal to or greater than 0.

2. The titanate photocatalyst of claim 1, wherein x and y are independently a value between 0.5 and 1, inclusively;

z and n are independently a value between 1 and 2, inclusively; and

D is nitrogen.

3. The titanate photocatalyst of claim 1, wherein m, x, y, n, and z are all 1 and D is nitrogen.

4. The titanate photocatalyst of claim 1, wherein m is 1;

x is 2;

y, z and n are all 1 and D is nitrogen.

5. A titanate photocatalyst of formula (Ia):

A_xTi_yO_zD_n 

 

(Ia)

wherein;

A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium;

D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine;

x and y are independently a value greater than 0 and equal to or less than 8; and

n and z are independently a value greater than 0 and equal to less than 8.

6. The titanate photocatalyst of claim 5, wherein A is caesium and D is nitrogen.

7. A method of producing a titanate photocatalyst of formula (Ia),

A_xTi_yO_zD_n 

 

(Ia)

wherein;

A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium;

D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine;

x and y are independently a value greater than 0 and equal to or less than 8; and

n and z are independently a value greater than 0 and equal to less than 8,

including the steps of;

a. forming a mixture comprising at least one cation donor precursor and at least one titanate precursor;

b. calcining the mixture to form a cation intercalated titanate;

c. contacting the cation intercalated titanate with a dopant and calcining to form the photocatalyst of formula (Ia).

8. The method of claim 7, wherein said at least one cation donor precursor is an alkali metal salt selected from the group consisting of alkali metal halides, alkali metal sulphides, alkali metal sulphates, alkali metal carbonates, alkali metal nitrates;

alkali metal hydroxides;

alkali metal acetates;

alkali metal dimethenylamine;

alkali metal oxide;

alkali metal chlorate, alkali metal phosphate and mixtures thereof.

9. The method of claim 7, wherein said at least one titanate precursor is selected from the group consisting of titanium nitride (TiN), titanium carbide (TiC), titanium cyanide (TiC_xN_y), titanium diboride (TiB₂), titanium sulphide (TiS₂), titanium halide, titanium oxide, titanium hydroxide, titanium phosphide (TiP), titanium sulphate, titanium silicides (TiSi₂), organic titanium compounds and mixtures thereof.

10. The method of claim 9, wherein the titanium halide is selected from the group consisting of TiBr₄, TiCl₄, TiCl₃, TiBr₃, TiF₃, TiF₄, and TiI₄.

11. The method of claim 9, wherein the titanium oxide is selected from the group consisting of TiO, Ti₂O₃, Ti₃O₅, TiO₂, TiO_xN_y, and TiO_xC_y, where x and y independently have a value of between 1 and 4, inclusively.

12. The method of claim 9, wherein the organic titanium compound is selected from the group consisting of Ti(OCH(CH₃)₂)₄, Ti[O(CH₂)₃CH₃]₄, and Ti(OCH₃)₄.(CH₃OH)_x, where x is a value greater than 0 and equal to or less than 8.

13. The method of claim 7, wherein said at least one cation donor precursor and said at least one titanate precursor are calcined at a temperature between 500°

C. to 1200°

C. for a period of between 0.5 to 40 hours.

14. The method of claim 7, wherein the dopant is a gas, which is selected from the group consisting of nitrogen, ammonia, methane, ethylene, propane, butane, fluorine, carbon monoxide, carbon dioxide and mixtures thereof.

15. The method of claim 7, wherein the dopant is one or more organic compounds selected from the group consisting of C₆H₁₂N₄, CO(NH₂)₂, CS(NH₂)₂, triethylamine, (NH₄)₂CO₃, C₂₅H₃₁N₃, C₁₂H₂₂O₁₁, C₂₅H₃₀O₅, C₆H₁₂, C₆H₁₂O₂, C₆H₁₂BNO₃, C₇H₅BF₄O₂, C₇H₇BO₄, H₃N.BH₃, C₆H₅N(C₂H₅)₂.BH₃, CS(NH₂)₂, C₇H₇SO₂, C₇H₁₂O₂S, C₆H₄S, C₄Cl₂F₆, C₄H₂F₂N₂, C₄H₈BrF, C₄H₉I, C₅H₃IO₂, C₅H₃FI, and C₆H₁₃I.

16. The method of claim 7, wherein the dopant is an inorganic compound or solution selected from the group consisting of:

carbon, boron, sulphur, ammonium sulphide, iodine, HIO₃, HIO₄, NH₄I, NH₄IO₃ and mixtures thereof.

17. The method of claim 7, wherein the cation intercalated titanate is calcined with the dopant at a temperature of between 200°

C. to 1800°

C. for a period between 30 mins and 5 days.

18. The method of claim 7, further including placing the titanate photocatalyst in an atmosphere having suitable light and converting an introduced pollutant to a substantially inert state.

19. A method of producing a layered titanate photocatalyst, including the steps of:

placing the photocatalyst of formula (Ia);

AxTiyOzDn 

 

(Ia)

wherein A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium,

D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine,

x and y are independently a value greater than 0 and equal to or less than 8,

and n and z are independently a value greater than 0 and equal to or less than 8,

in an acidic solution to form the photocatalyst of formula (I);

H_mA_x-mTi_yO_zD_n 

 

(I)

wherein;

A is a cation selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and francium;

D is a dopant selected from the group consisting of boron, carbon, nitrogen, fluorine, sulphur, phosphorus and iodine;

x is a value greater than 0 and less than or equal to 8;

y is a value greater than 0 and less than or equal to 8;

n is a value greater than 0 and less than or equal to 8;

z is a value greater than 0 and less than or equal to 8;

m is a value greater than 0 and less than or equal to 8; and

x-m is a value equal to or greater than 0;

and filtering, separating and drying the titanate photocatalyst of formula (I).

20. The method of claim 19, wherein the acidic solution is selected from the group consisting of hydrochloric acid (HCl), nitric acid (HNO₃), sulphuric acid (H₂SO₄), phosphoric acid, hydrogen fluorine, hydrogen iodine, hydrogen bromide, acetic acid (HAC), perchlorate acid, iodic acid (HIO₃), periodic acid (HIO₄) and mixtures thereof.