JP2002177775A - Visible ray reaction type photocatalyst and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable visible-ray-reaction type photocatalyst that is comparatively easy to produce and a manufacturing method thereof. SOLUTION: The visible-ray-reaction type photocatalyst is obtained by adding hydrogen peroxide water into a 1st solution which contains one or more kinds of metals selected from the group of V, Fe, Ni, Cu, Cr, Mg, Ag, Mn, Pd, and Pt, and titanium, or a 2nd solution which is prepared by dispersing a hydroxide, oxide or complex obtained by adding hydrogen peroxide into the 1st solution to react.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
Decompose organic compounds and nitrogen oxides by photocatalytic reaction,
Alternatively, the present invention relates to a visible light reactive photocatalyst having an action such as sterilization and deodorization, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, photoreactions using titanium oxide as a catalyst for decomposing organic compounds and nitrogen oxides in waste liquid or air have been practically used. The applicant has also put it into practical use. When the titanium oxide is used as a catalyst, the light to be irradiated is light included in light such as sunlight or a fluorescent light, which is nearby.
So-called ultraviolet light having a wavelength of 400 nm or less contributes to the photoreaction. However, the above-mentioned sunlight or fluorescent lamp has
The ratio of ultraviolet light having a wavelength of 00 nm or less to the total amount of ultraviolet light is relatively small. Therefore, in the related art, in order to effectively generate a photoreaction, light having a wavelength suitable for the photoreaction is irradiated with “ultraviolet light”. A lamp is needed.

[0003] Under such circumstances, a "visible light-reactive photocatalyst" which is most easily used, that is, generates a photoreaction with the most familiar visible light of the sunlight or the fluorescent lamp, has been developed. Recently, it has attracted attention. However, it is difficult to easily produce a stable “visible light-reaction type photocatalyst”, and at present, an “ion implantation type” in which metal ions are implanted into titanium oxide has been proposed. However, in the case of the “ion implantation method”, since metal ions are implanted into titanium oxide with large energy, a large-scale facility is required. In addition, there has been proposed an "oxygen depletion type" production method in which one of the oxygen molecules of titanium oxide is deleted. Thus, there is a problem in that it is difficult to stabilize in that state (a state where oxygen is lacking) for a long time.

[0004] Under such circumstances, it is the current situation that each photocatalyst maker makes trial and error.

The present invention has been made in view of such a situation, and has as its object to provide a relatively simple and stable "visible light-reaction type photocatalyst" and a method for producing the same.

[0006]

The visible light reaction type photocatalyst according to the first invention comprises V, Fe, Ni, Cu, Cr,
A first solution containing one or more metals selected from the group consisting of Mg, Ag, Mn, Pd, and Pt and titanium, or obtained by adding a hydrogen peroxide solution to the first solution. Hydrogen peroxide water is added to any one of a hydroxide, a hydrate, an oxide or a complex, or a dispersion solution in which any of the above hydroxide, hydrate, oxide or a complex is dispersed. Characterized in that it is obtained by reacting

According to the visible light reaction type photocatalyst, V, Fe, Ni, Cu, Cr, Mg, Ag, M
one or more metals selected from the group consisting of n, Pd, and Pt;
The addition of the aqueous hydrogen peroxide causes the peroxo group to intervene, thereby keeping the titanium and the metal dispersed in the solution, so that the metal is incorporated into the titanium. For this reason, it is activated also for visible light. (Of course, it is activated against ultraviolet rays in the same manner as titanium oxide.)
The visible light reaction type photocatalyst can be easily and easily produced without requiring large energy or equipment, and is stable in composition for a long time after production.

The method for producing a visible light reactive photocatalyst according to the second aspect of the present invention comprises the steps of: adding titanium, V, Fe,
A first step of obtaining a first solution containing at least one metal selected from the group consisting of Ni, Cu, Cr, Mg, Ag, Mn, Pd, and Pt; A second step of adding a hydrogen peroxide solution to the first solution to cause a reaction.

The method for producing a visible light reactive photocatalyst according to the third aspect of the present invention comprises the steps of: adding titanium, V, Fe,
A first step of containing at least one metal selected from the group consisting of Ni, Cu, Cr, Mg, Ag, Mn, Pd, and Pt; and a first solution generated in the first step, A second step of adding a hydrogen peroxide solution to obtain a dispersion solution in which a hydroxide, hydrate, oxide or complex of titanium is dispersed, and reacting by adding a hydrogen peroxide solution to the dispersion solution. And a third step of causing

According to the second and third aspects of the present invention, the visible light reaction type photocatalyst according to the first aspect of the invention is chemically stable without requiring large energy and equipment. Obtainable.

In the first invention, the photocatalyst in the form of visible light reactive type photocatalyst fine particles formed in a solution, which is obtained by further performing a heat treatment,
By simply applying the solution on a support, a support capable of causing a photocatalytic reaction by visible light on the surface after drying can be easily obtained. In such a case, since the peroxo group is interposed, thereby crystallizing the titanium and the metal in a state of being dispersed in the solution, the crystallized photocatalyst is exposed to visible light. Higher activation (eg, about twice as much activation as without heating under the same conditions, as described in the examples below)
Is shown.

In the first aspect of the present invention, the photocatalyst in the form of a powder, which is obtained by further drying, becomes a visible light reaction type photocatalyst that is convenient for storage and transportation.

[0013] In the second or third invention,
If the subsequent step further includes a step of performing pressure / heat treatment, a photocatalyst in a form in which visible light reactive type photocatalyst fine particles are generated in a solution can be generated. In such a case, since the peroxo group is interposed, thereby crystallizing the titanium and the metal in a state of being dispersed in the solution, the crystallized photocatalyst is exposed to visible light. It shows higher activation (eg, about twice as much activation without heating under the same conditions, as described in the examples below).

In the above invention, a powdery visible light reaction type photocatalyst can be obtained by having a drying step after the pressurizing / heating step.
In such a case, it is in a form convenient for storage or transportation as a product.

[0015] In the first to third inventions, the solution containing titanium and the one or more metals may further comprise:
When the basic substance is added, the solution is neutralized, and the acid does not damage the support side when the photocatalyst is applied to the support surface. Further, it is preferable in that it has an effect of facilitating precipitation of hydroxide.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described specifically. However, it is not limited only to this embodiment. Example 1 Vanadyl sulfate 0.0 in 450 cc of distilled water
After dissolving 1 g, 2.6 cc of 97% titanium tetrachloride is added to the solution.

Next, the solution obtained in the above step (first solution)
Then, distilled water is added thereto to prepare a 500 cc vanadium / titanium mixed solution.

Next, an aqueous ammonia solution having a concentration of 3% is added to the prepared solution until the pH becomes 7 (neutral).

Dehydration and washing operations are repeated as appropriate on the vanadium / titanium precipitated gel (a hydroxide, hydrate, oxide or complex gel) precipitated in the solution after the addition. Then, distilled water was again added to the resulting gel to form a 90 cc suspension solution (dispersion solution). To this suspension solution, 10 cc of 30% hydrogen peroxide solution was added.
The mixture is stirred for one day and night with a stirrer to obtain a visible light reactive type photocatalyst forming liquid.

Next, half the amount of the obtained liquid for forming a photocatalyst is subjected to a heating treatment (heating and pressurizing treatment) at 100 ° C. for 8 hours in an autoclave, so that the visible light reactive type photocatalyst fine particles are dissolved. Form inside. In this solution, the vanadium / titanium oxide fine particles were dispersed in the solution in a stable state,
It becomes a visible light reactive liquid for photocatalyst formation. The other half of the “liquid for forming a visible light-reactive photocatalyst” that was not heat-treated in the autoclave and the “visible light reaction in which the vanadium-titanium oxide fine particles obtained by the heat treatment were stably dispersed. And an equal amount of a liquid for forming a photocatalyst. A glass plate is immersed in the mixed solution to coat a visible light reactive photocatalyst in the solution (film formation) on the surface of the glass plate. next,
The coated glass plate is heated and cured at 300 ° C. to produce a visible light reactive type glass plate with a photocatalytic film.

Using the above-mentioned glass plate with a photocatalytic film of the visible light reaction type, the photoreaction by visible light was confirmed. That is, it was immersed in a 500 ppm methylene blue solution, and methylene blue was applied to the surface of a glass plate. The glass plate was irradiated with light from a 70 W metal halide lamp while cutting light having a wavelength of 400 nm or less with an ultraviolet cut film. Then, 20 hours after the irradiation, the color was completely bleached. That is, it was confirmed that a photoreaction occurred.

For comparison, an experiment was conducted to confirm the effect of the photoreaction by using a photocatalyst solution in which vanadium (V) was not mixed and coated on the surface of a glass plate under the same manufacturing conditions as in the above example. The above 7
Irradiation with a 0 W metal halide lamp for the same time (20 hours) did not change the color of the glass plate surface at all. That is, when vanadium (V) is not added,
It was confirmed that no visible light response was generated. [Example 2] In the above "Example 1", only half the amount of the "visible light-reactive photocatalyst forming liquid" was treated in an autoclave.
Heat treatment is performed at 0 ° C. for 8 hours to form visible light reactive photocatalyst fine particles in the solution, thereby obtaining a liquid in which vanadium / titanium oxide particles are stably dispersed. This solution is further heated at 150 ° C. to obtain a powder of vanadium / titanium oxide particles.

Using the powder of the vanadium / titanium oxide particles, the following experiment was conducted for the photocatalytic action of the visible light reaction type. That is, in a quartz glass reaction vessel,
20 cc of a 10 ppm acetic acid solution is added by TOC, and vanadium / titanium oxide particles are added to the solution at 500 ppm.
Add so that The added solution was irradiated with 70 W metal halide lamp light as visible light in a state where light having a wavelength of 400 nm or less was cut by an ultraviolet cut film.
C reduced by 50%. That is, it was confirmed that acetic acid could be mineralized (decomposed) by the visible light and the photocatalyst.

As a comparative experiment, a similar experiment was carried out using powder of titanium oxide particles containing no vanadium. Similarly, after 3 hours of irradiation, no decrease in acetic acid concentration was observed in TOC after irradiation for 3 hours.

The following experiment was conducted on the visible light reaction type photocatalysis using the above-mentioned vanadium / titanium oxide particles. That is, 20 cc of a 1 ppm aqueous solution of methylene blue is charged into a reaction vessel made of quartz glass, and vanadium / titanium oxide particles are added until the concentration becomes 500 ppm. The solution after the addition was irradiated with 70 W light of a metal halide lamp as visible light in a state where the light having a wavelength of 400 nm or less was cut by an ultraviolet cut film, and completely decolorized 6 hours after the irradiation.

For comparison, an experiment was carried out under the same conditions as those of the above-mentioned embodiment, except that vanadium (V) was not mixed, and the light was irradiated from the above 70 W metal halide lamp under the same conditions. The color of the glass plate surface did not change at all. That is, it was confirmed that when vanadium (V) was not added, visible light responsiveness did not occur.

For comparison, a suspension was prepared in the same manner as in the above example, except that the "concentration of 30
% Hydrogen peroxide solution ", the experiment was carried out. The light from the 70 W metal halide lamp was irradiated under the same conditions, but the color of the glass plate surface did not change at all. In other words, when "hydrogen peroxide solution" is not added, since the peroxo group is not interposed, titanium and the metal (in this case, "V") are not dispersed,
Therefore, it is presumed that no visible light response occurs.

Next, using the powder of the above-mentioned vanadium / titanium oxide particles, the photoreaction under ultraviolet light other than visible light was confirmed by the following experiment. That is, 120 cc of a 30 ppm acetic acid solution in TOC is charged into a Pyrex (registered trademark) glass reaction vessel, and vanadium / titanium oxide particles are added until the concentration becomes 500 ppm. When this solution was irradiated with a 6 W germicidal lamp as irradiation light, the TOC decreased by about 30% in 3 hours after irradiation. Similarly, when titanium oxide particles were used in place of the vanadium / titanium oxide particles, the TOC also reduced about 30%.

As described above, according to the liquid and powder for forming a visible light-reactive photocatalyst according to the present invention, a photoreaction can be performed in response to visible light, and ultraviolet light other than visible light can be used. The reaction (photolysis) was confirmed to be similar to that of titanium oxide.

[0030]

According to the visible light reactive photocatalyst and the method for producing the same according to the present invention, a stable "visible light reactive photocatalyst" can be relatively easily produced without requiring large energy. The resulting visible light reactive photocatalyst performs a photoreaction in response to both visible light and ultraviolet light. Therefore, harmful substances can be efficiently decomposed by sunlight or familiar light such as a fluorescent lamp.

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Claims (7)

[Claims] 1. V, Fe, Ni, Cu, Cr, Mg, A
g, a first solution containing one or more metals selected from the group consisting of Mn, Pd, and Pt, and titanium, or a hydroxide obtained by adding aqueous hydrogen peroxide to the first solution. object,
Adding a hydrogen peroxide solution to any one of a hydrate, an oxide, or a complex, or a dispersion solution in which any of the above hydroxide, hydrate, oxide, or complex is dispersed; A visible light reaction type photocatalyst obtained by the following method. 2. The visible light reactive type according to claim 1, wherein the photocatalyst is a form in which visible light reactive type photocatalyst fine particles are formed in a solution, which is obtained by further performing pressure and heat treatment. Photocatalyst. 3. Obtained by further drying.
3. A photocatalyst in the form of a powder.
The visible light-reactive photocatalyst according to the above. 4. A solution comprising titanium, V, Fe, Ni, C
a first step of obtaining a first solution containing at least one metal selected from the group consisting of u, Cr, Mg, Ag, Mn, Pd, and Pt; and a first step formed in the first step. In the solution of 1,
A method for producing a visible-light-reactive photocatalyst, comprising a second step of reacting by adding aqueous hydrogen peroxide. 5. A solution comprising titanium, V, Fe, Ni, C
a first step of containing at least one metal selected from the group consisting of u, Cr, Mg, Ag, Mn, Pd, and Pt; and a solution of hydrogen peroxide in the solution produced in the first step. A second step of obtaining a dispersion in which hydroxides, hydrates, oxides or complexes of titanium are dispersed, and a third step of reacting by adding aqueous hydrogen peroxide to the dispersion. A method for producing a visible light reactive photocatalyst, comprising: 6. The method for producing a visible light-reactive photocatalyst according to claim 4, further comprising a step of performing a pressure / heat treatment in a subsequent step. 7. The visible light-reactive photocatalyst according to claim 6, further comprising a drying step after the pressurizing / heating step in order to make the visible light-reactive photocatalyst powdery. Manufacturing method.