Nanostructured titanium oxide material and its synthesis procedure

• US 7,799,313 B2
• Filed: 11/23/2009
• Issued: 09/21/2010
• Est. Priority Date: 10/10/2003
• Status: Active Grant

• Current Assignee: Instituto Mexicano Del Petrã³Leo (Gobierno Federal De Los Estados Unidos Mexicanos)
• Original Assignee: Instituto Mexicano Del Petrã³Leo (Gobierno Federal De Los Estados Unidos Mexicanos)
• Inventors: Cortes Jacome, Maria Antonia, Angeles Chavez, Carlos, Lopez Salinas, Esteban, Toledo Antonio, Jose Antonio, Alvarez Ramirez, Fernando, Lozada y Cassou, Marcelo, Ferrat Torres, Gerardo, Flores Ortiz, Luis Francisco, Ruiz Morales, Yosadara
• Primary Examiner(s): Silverman; Stanley
• Assistant Examiner(s): Zimmer; Anthony J
• Application Number:
  US12/623,993
• Publication Number:
  US 20100069233A1
• Time in Patent Office: 302 Days
• Field of Search: 423/608, 423/609, 423/610, 423/611, 423/612, 423/613, 423/614, 977/734, 977/742, 977/811
• US Class Current: 423/609
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 23/04 Oxides; Hydroxides
• CPC Class Codes: C01G 23/043 Titanium sub-oxides
• CPC Class Codes: C01G 23/047 Titanium dioxide
• CPC Class Codes: C01P 2002/76 by a space-group or by other symmetry indications
• CPC Class Codes: C01P 2002/77 by unit-cell parameters, atom positions or structure diagrams
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/13 Nanotubes
• CPC Class Codes: C01P 2004/16 Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer
• CPC Class Codes: Y10S 977/811 Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/2975 Tubular or cellular
• CPC Class Codes: Y10T 428/298 Physical dimension
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

Nanomaterials of the JT phase of the titanium oxide TiO_2−x, where 0≦x≦1 having as a building block a crystalline structure with an orthorhombic symmetry and described by at least one of the space groups 59 Pmmn, 63 Amma, 71 Immm or 63 Bmmb. These nanomaterials are in the form of nanofibers, nanowires, nanorods, nanoscrolls and/or nanotubes. The nanomaterials are obtained from a hydrogen titanate and/or a mixed sodium and hydrogen titanate precursor compound that is isostructural to the JT crystalline structure. The titanates are the hydrogenated, the protonated, the hydrated and/or the alkalinized phases of the JT crystalline phase that are obtained from titanium compounds such as titanium oxide with an anatase crystalline structure, amorphous titanium oxide, and titanium oxide with a rutile crystalline structure, and/or directly from the rutile mineral and/or from ilmenite. The titanates are submitted to dynamic thermal treatment in an inert, oxidizing or reducing atmosphere to produce the JT phase of the TiO_2−x, where 0≦x≦1 with an orthorhombic structure.

Claims

1. A method for the synthesis of titanium oxide of the formula TiO₂₋

x, where 0≦

x≦

1, having an orthorhombic crystalline lattice which is described by at least one of the space groups selected from the group consisting of 59 Pmmn, 63 Amma, 71 Immm and 63 Bmmb, and having nanofibrilar and/or nanotubular morphology, comprising heating a hydrogen titanate and/or a mixed sodium and hydrogen titanate under dynamic thermal treatment to produce a stable nanomaterial.

2. The method of claim 1, wherein said hydrogen titanate and/or mixed sodium and hydrogen titanate are obtained by mixing a titanium oxide compound with an alkaline solution under hydrothermal conditions in a closed system or under thermal conditions at atmospheric pressure in reflux conditions, followed by an ionic exchange treatment.

3. The method of claim 2, wherein said method is conducted under hydrothermal conditions in said closed system with an autogenous pressure in the range of from 1 to 150 atm, a temperature in the range of from 80°

C. to 160°

C., and a reaction time in the range of 1 to 80 hours.

4. The method of claim 2, wherein said method is conducted under atmospheric pressure in reflux conditions at a temperature in the range of from 80°

C. to 160°

C., for a reaction time in the range of from 1 to 80 hours.

5. The method of claim 1, wherein said dynamic thermal treatment is conducted by flowing an oxidizing gas, an inert gas, or a mixture of an inert gas and a reducing gas through said hydrogen titanate and/or mixed sodium and hydrogen titanate at a temperature between 200°

C. and 500°

C.

6. The method of claim 5, wherein said dynamic thermal treatment is performed with flowing air or O₂ to achieve an oxidizing atmosphere;

in flowing nitrogen, He or Ar to achieve an inert atmosphere;

or with a mixture of flowing inert gas and H₂ with a H₂ concentration of 5% to 30% by volume based on the total volume of gas.

7. The method of claim 5, wherein said dynamic thermal treatment is conducted at a temperature between 200°

C. and 450°

C.

8. The method of claim 5, wherein said dynamic thermal treatment is conducted at a temperature between 200°

C. and 400°

C.

9. The method of claim 5, wherein said dynamic thermal treatment is conducted with a flowing gas rate of 0.1 liter per minute to 1.0 liter per minute.

10. The method of claim 5, wherein said dynamic thermal treatment is conducted with a flowing gas rate of 0.3 liter per minute to 0.5 liter per minute.

11. The method of claim 2, wherein said titanium oxide compound is anatase having a crystal size between 5 nm and 10 nm.

12. The method of claim 2, wherein said titanium oxide compound is amorphous titania having a crystal size between 0.1 nm to 5 nm.

13. The method of claim 2, wherein said titanium oxide compound is amorphous titania having a crystal size between 1 to 3 nm.

14. The method of claim 2, wherein said ionic exchange treatment is in alcoholic media, acidic aqueous media or aqueous media.