PHOTOCATALYTIC MATERIAL, PHOTOCATALYST, PHOTOCATALYTIC PRODUCT, LIGHTING APPARATUS, AND METHOD OF PRODUCING PHOTOCATALYTIC MATERIAL

Abstract

A photocatalytic material containing tungsten trioxide fine particles having an average particle diameter of 0.5 μm or smaller and a crystal structure of a monoclinic crystal system as a main component.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIGS. 1A and 1B show schematic explanatory drawings of a fluorescent lamp according to the invention;

FIGS. 2A and 2B show conceptual explanatory drawings of a deodorization unit according to the invention;

FIG. 3 shows X-ray diffraction data of monoclinic crystal system WO₃ which is a main component of the photocatalyst powder of the invention;

FIG. 4 shows X-ray diffraction patterns of triclinic crystal system and monoclinic crystal system of tungsten trioxide (WO₃);

FIG. 5 shows a characteristic drawing showing the comparison of acetaldehyde decomposition effects in the case where the crystal structures of tungsten trioxide differ;

FIG. 6 shows a conceptual drawing of a measurement apparatus employed for obtaining the characteristic drawing of FIG. 5;

FIG. 7 shows a conceptual drawing of a production apparatus for producing the photocatalytic material of the invention;

FIG. 8 shows a graph of particle size distribution (the relation among frequency, the particle diameter and the integrated penetration) after dispersion;

FIG. 9 shows a graph of particle size distribution (the relation among frequency, the particle diameter and the integrated penetration) of the WO₃-dispersed coating material;

FIG. 10 shows a microscopic photograph of ammonium meta-tungstate as a granular raw material obtained in a third embodiment;

FIG. 11 shows a microscopic photograph of monoclinic crystal system type WO₃ crystal photocatalyst fine particles obtained by rapid and short time heating of the granular raw material obtained in the third embodiment at 800° C. for 1 to 10 minutes;

FIG. 12 shows a characteristic drawing showing the acetaldehyde decomposition capability of the respective tungsten trioxide photocatalyst fine particles obtained by firing at a temperature of 600° C., 700° C., 800° C., and 900° C. in a fourth embodiment;

FIG. 13 shows a characteristic drawing showing the acetaldehyde decomposition capability of the respective tungsten trioxide photocatalyst fine particles obtained by firing at a temperature of 600° C., 700° C., 800° C., and 900° C. in the fourth embodiment;

FIG. 14 shows a characteristic drawing showing the acetaldehyde decomposition capability in the case where the firing time is changed to be 30 seconds, 1 minute, 5 minutes, 10 minutes, and 15 minutes;

FIG. 15 shows a drawing showing the relation between the wavelength and the reflectivity in the case of using WO₃ photocatalyst of a sixth embodiment and TiO₂ photocatalyst;

FIG. 16 shows a perspective view in the disassembled state of the lighting apparatus according to the sixth embodiment;

FIG. 17 shows an enlarged cross-sectional drawing of the main part of FIG. 16; and

FIG. 18 shows the relation between the time and the acetaldehyde remaining ratio by using the lighting apparatus of a seventh embodiment in combination with a TiO₂ photocatalyst-bearing fluorescent lamp, the TiO₂ photocatalyst-bearing fluorescent lamp, and a TiO₂ photocatalyst-bearing lighting apparatus in combination with the TiO₂ photocatalyst-bearing fluorescent lamp.

Claims

1. A photocatalytic material containing tungsten trioxide fine particles having an average particle diameter of 0.5 μm or smaller and a crystal structure of a monoclinic crystal system as a main component.

2. A photocatalyst body comprising a layer of the photocatalytic material according to claim 1 formed on a substrate surface and a photocatalyst film containing tungsten trioxide fine particles maintaining a crystal structure of a monoclinic crystal system and formed on the layer of the photocatalytic material.

3. A photocatalytic product comprising a photocatalyst filter and a light emitting diode which radiates light including at least blue color light to the photocatalyst filter, wherein the photocatalytic material according to claim 1 is deposited on the photocatalyst filter and tungsten trioxide fine particles maintain a crystal structure of a monoclinic crystal system after deposition.

4. A lighting apparatus comprising a light source, a light transmissive cover substrate enveloping the light source, and a photocatalyst layer formed on an outer face or an inner face of the cover substrate and containing tungsten trioxide fine particles having an average particle diameter of 0.1 μm or smaller and a crystal structure of a monoclinic crystal system.

5. A lighting apparatus comprising a light source, a reflection plate substrate set optically on the opposite to the light source, and a photocatalyst layer formed on the reflection plate substrate and containing tungsten trioxide fine particles having an average particle diameter of 0.1 μm or smaller and a crystal structure of a monoclinic crystal system.

6. A method of producing a photocatalytic material comprising the steps of producing a granular raw material by spraying an aqueous solution containing 1 to 20% by weight of ammonium para-tungstate in high temperature atmosphere, and forming tungsten trioxide fine particles having a crystal structure of a monoclinic crystal system by heating the granular raw material at 700 to 800° C. for 1 to 10 minutes.

7. A method of producing a photocatalytic material comprising the steps of dissolving ammonium para-tungstate in a water-based solvent and successively carrying out recrystallization, and forming a tungsten trioxide photocatalytic material by firing the obtained crystal in conditions of 600° C. or higher for 15 seconds or longer.