Method for applying photocatalytic coatings without using binders, and use of a coating

Abstract

The invention relates to a method for applying titanium dioxide-based photocatalytic coatings to a carrier material without using binders. The invention also relates to the use of a coating. According to the invention, a titanium dioxide suspension together with a carrier liquid is sprayed onto a hot carrier in the form of a fine aerosol so that the carrier liquid flash evaporates and titanium dioxide particles of the titanium dioxide suspension are flash sintered onto the carrier material, water being used as the carrier liquid and the carrier material having a temperature of 150 to 250° C. during spraying. According to the invention, a porous and yet stable layer for a catalyst for an efficient and rapid degradation of pollutants is produced.

Claims

1. A method for binder-free application of titanium dioxide-based photocatalytic coatings to a support material, where a titanium dioxide suspension with a carrier liquid is sprayed in a form of a fine aerosol onto a hot support, so that the carrier liquid undergoes flash evaporation and the titanium dioxide particles of the titanium dioxide suspension undergo flash sintering onto the support material, the carrier liquid being water, characterized in that during the sprayed application, the support material has a temperature of 150 to 250° C., thus forming a porous and yet stable layer for a catalyst for pollutant degradation, heat is generated in the support material itself, and the support material is traversed by an electrical current.

2. The method as claimed in claim 1, characterized in that during the sprayed application, the support material has a temperature which lies above the boiling temperature of the carrier liquid.

3. The method as claimed in claim 2, wherein the titanium dioxide suspension has a fraction of 5 to 20 mass % of the titanium dioxide particles.

4. The method as claimed in claim 3, wherein the method is repeated.

5. The method as claimed in claim 2, wherein the method is repeated.

6. The method as claimed in claim 2, wherein a latticelike support material is used.

7. The method as claimed in claim 2, wherein nonrusting material is used as the support material.

8. The use of a titanium dioxide-based coating on a support material, produced by the method as claimed in claim 2, for a catalyst for pollutant degradation.

9. The method as claimed in claim 1, characterized in that the titanium dioxide suspension has a fraction of 5 to 20 mass % of the titanium dioxide particles.

10. The method as claimed in claim 9, wherein the method is repeated.

11. The method as claimed in claim 9, wherein a latticelike support material is used.

12. The method as claimed in claim 9, wherein nonrusting material is used as the support material.

13. The use of a titanium dioxide-based coating on a support material, produced by the method as claimed in claim 9, for a catalyst for pollutant degradation.

14. The method as claimed in claim 1, characterized in that the method is repeated.

15. The method as claimed in claim 14, wherein a latticelike support material is used.

16. The method as claimed in claim 14, wherein nonrusting material is used as the support material.

17. The use of a titanium dioxide-based coating on a support material, produced by the method as claimed in claim 14, for a catalyst for pollutant degradation.

18. The method as claimed in claim 1, characterized in that a latticelike support material is used.

19. The method as claimed in claim 1, characterized in that nonrusting material is used as the support material.

20. The use of a titanium dioxide-based coating on a support material, produced by the method as claimed in claim 1, for a catalyst for pollutant degradation.

Description

(1) An exemplary embodiment of the invention is elucidated in more detail below.

(2) The example explains the coating of a support material which consists of a fine-mesh metal lattice. Lattices of this kind are highly suited to use for the treatment of liquids and gases flowing through them, for the purpose, for example, of air and water purification.

(3) The lattice consists of a net of stainless steel wire. The mesh size is 0.25 mm and the wire diameter is 0.16 mm. The metal lattice is rectangular and fixed in on two opposite sides, with a flow through the lattice of current, which heats the metal lattice to a temperature of around 200° C. Using a commercial spray gun, the titanium dioxide suspension is sprayed in the form of a fine aerosol, consisting of water and a titanium dioxide powder, onto the hot metal lattice. The water here undergoes flash evaporation and the titanium dioxide powder which remains combines in a sintering process with the support material. A uniform layer of titanium dioxide is generated on the support material. Sprayed application is repeated as many times as needed to achieve the desired layer thickness. It is possible in this way to generate layer thicknesses of 0.5 to 40 g/m.sup.2 with high mechanical strength.