JP2018079432A - Iron compound-supported titanium oxide photocatalyst - Google Patents

Abstract

Provided is a highly active photocatalyst having excellent responsiveness to both visible light and ultraviolet light, and a method for producing the same. The photocatalyst of the present invention is a photocatalyst having a structure in which an iron compound is supported on the surface of titanium oxide, wherein the specific surface area of the titanium oxide (measured by a BET method) is in a range of 7 to 55 m2 / g. The titanium oxide has a crystal type in which rutile type and anatase type are mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)). The photocatalyst has a crystal type in which rutile type and anatase type are mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)), and has a specific surface area (by BET method measurement). Can be produced through a step of supporting iron (III) chloride on titanium oxide having a range of 7 to 55 m2 / g. [Selection diagram] None

Description

  The present invention relates to an iron compound-supported titanium oxide photocatalyst, a production method thereof, a coating liquid containing the photocatalyst, and a photocatalyst-coated body provided with a coating layer containing the photocatalyst.

And radicals having a strong oxidizing power is irradiated with ultraviolet rays of titanium oxide is generated, an organic compound (e.g., dirt, malodorous gas, etc.) oxidation and decomposition of the oxidation of inorganic compounds (e.g., NOx, NH _3, etc.), viruses, Since it is effective in killing and inactivating bacteria and molds, it has been applied to environmental purification, deodorization, antifouling, antibacterial, and antifungal in recent years. However, although titanium oxide can exhibit excellent photocatalytic activity under sunlight, the amount of ultraviolet rays contained in light sources in ordinary living spaces such as incandescent lamps and fluorescent lamps is as low as 4%, and most of them are visible light. Therefore, there is a problem that sufficient photocatalytic ability cannot be exhibited under such a light source.

As a method for solving the above problem, a method of imparting visible light responsiveness by supporting titanium or a specific metal (for example, an iron compound) on titanium oxide is known. In Patent Document 1, titanium oxide having a crystal form in which rutile type and anatase type are mixed (mixing ratio of rutile type and anatase type (X-ray diffraction peak intensity ratio) = about 20/80, trade name “AEROXIDE TiO ₂ P25”. "Japan Aerosil Co., Ltd., Ltd.) was immersed in Fe (acac) ₃ solution, the surface of the titanium oxide by supporting Fe (acac) ₃ complex, then, the iron oxide the Fe (acac) ₃ complex by firing It is described that the iron oxide-supported titanium oxide obtained by the above has excellent visible light responsiveness and exhibits excellent photocatalytic activity when irradiated with either visible light or ultraviolet light. However, the photocatalytic activity is still insufficient.

JP2012-153591A

Accordingly, an object of the present invention is to provide a highly active photocatalyst having excellent responsiveness to both visible light and ultraviolet light.
Another object of the present invention is to provide a method for producing a highly active photocatalyst having excellent responsiveness to both visible light and ultraviolet light.
Another object of the present invention is to provide a coating liquid containing a highly active photocatalyst having excellent responsiveness to both visible light and ultraviolet light.
Another object of the present invention is to provide a photocatalyst-coated body having a coating layer containing a highly active photocatalyst having excellent responsiveness to both visible light and ultraviolet light.

  As a result of diligent studies to solve the above problems, the present inventors have found that a photocatalyst obtained by supporting an iron compound on titanium oxide has a titanium oxide having a crystal type in which a rutile type and an anatase type are mixed at a specific ratio. When used, the photocatalytic activity by irradiation with visible light or ultraviolet light is improved, and further, when the excitation light is irradiated when supporting an iron compound, the photocatalytic activity by irradiation with visible light or ultraviolet light is dramatically improved. I found. The present invention has been completed based on these findings.

  In the present specification, “ppm” other than “volume ppm” is “ppm by weight”.

That is, the present invention is a photocatalyst having a structure in which an iron compound is supported on the surface of titanium oxide, wherein the titanium oxide has a specific surface area (measured by a BET method) in the range of 7 to 55 m ² / g, The present invention provides a photocatalyst characterized by having a crystal type in which rutile type and anatase type are mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)).

In the present invention, 200 mg of the photocatalyst is charged in a reaction vessel (volume: 200 mL), and the reaction vessel is filled with methanol gas (air dilution, 800 ppm by volume) at 25 ° C. for 24 hours. Provided is the photocatalyst, wherein the amount of carbon dioxide produced (concentration conversion) in the reaction vessel upon light irradiation (light source: 405 nm LED, illuminance: 2.5 W / m ² ) is 300 ppm by volume or more.

  The present invention also has an iron element content of 50 to 2000 ppm, a chlorine atom content of 50 to 1400 ppm, and an iron element content / chlorine atom content (weight ratio) of 1.50 or less, based on titanium oxide. The above photocatalyst is provided.

The present invention also has a crystal type in which rutile type and anatase type are mixed in the range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)), and the specific surface area (BET method measurement) According to the present invention, there is provided a method for producing a photocatalyst, wherein the photocatalyst is obtained through a step of supporting iron (III) chloride on titanium oxide having a range of 7 to 55 m ² / g.

  The present invention also provides the method for producing the photocatalyst, wherein the excitation light is irradiated when iron (III) chloride is supported on titanium oxide.

  The present invention also provides a coating liquid containing the photocatalyst.

  The present invention also provides a photocatalyst-coated body provided with a coating layer containing the above-mentioned photocatalyst on the surface of a substrate.

  The photocatalyst of the present invention absorbs light in a wide wavelength range from the ultraviolet region to the visible light region, thereby generating holes in the valence band, excited electrons in the conduction band, and oxidizing various substances attached to the surface of the photocatalyst. Or it reduces and expresses environmental purification, deodorization, antifouling, antibacterial, or antifungal effect. Therefore, the photocatalyst of the present invention can exhibit excellent photocatalytic ability using not only sunlight but also a light source with a small amount of ultraviolet light in a normal living space such as an incandescent lamp, a fluorescent lamp, and an LED light, Conventionally, it can be suitably used for environmental purification or the like in a space where it has been difficult to sufficiently exhibit the photocatalytic activity, such as in a car or indoors.

It is a figure which shows the photocatalytic activity of the photocatalyst obtained by the Example and the comparative example. It is a figure which shows the photocatalytic activity of the photocatalyst obtained by the Example and the comparative example.

[photocatalyst]
The photocatalyst of the present invention is a photocatalyst having a structure in which an iron compound is supported on the surface of titanium oxide, wherein the titanium oxide has a specific surface area (measured by BET method) in the range of 7 to 55 m ² / g, Is characterized in that the rutile type and the anatase type have a crystal type mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)).

  The titanium oxide in the present invention has a crystal type in which a rutile type and an anatase type are mixed. The titanium oxide in the present invention may further include other types (for example, brookite type), but the rutile X-ray diffraction peak intensity and the anatase type X-ray in the X-ray diffraction peak intensity of all titanium oxides. The proportion of the total diffraction peak intensity is, for example, 60% or more, preferably 70% or more, particularly preferably 80% or more, and most preferably 90% or more. The upper limit is 100%. That is, the content ratio of other types (when two or more types are included, the total content ratio) is, for example, 40% or less, preferably 30% or less, particularly preferably 20% or less, and most preferably 10% or less.

  The mixing ratio (the former / the latter (X-ray diffraction peak intensity ratio)) of the rutile type and the anatase type in the titanium oxide is 30/70 to 95/5, and preferably 35/65 from the viewpoint of further improving the catalytic activity. ~ 90/10, particularly preferably 40/60 to 85/15, most preferably more than 50/50, 85/15 or less, particularly preferably more than 50/50 and 80/20 or less. If the mixing ratio of the rutile type and the anatase type is out of the above range, the catalytic activity is lowered, which is not preferable.

  In the present invention, the mixing ratio of rutile type and anatase type in titanium oxide is indicated by the X-ray diffraction peak intensity ratio. The X-ray diffraction peak intensity ratio can be calculated from the intensity ratio of the strongest diffraction lines of the rutile type crystal and the anatase type crystal. For example, when a Cu tube is used as the X-ray diffractometer, 2θ = 25. It can be calculated from the ratio of the peak tops of both diffraction lines seen at around 3 ° and around 2θ = 27.4 °.

The specific surface area of titanium oxide and rutile type and anatase type has a crystal form mixed in the above range (by BET method measurement) in the range of 7~55m ² / g, preferably 7m ² / g or more, 50 m ² / g, more preferably 10 to 45 m ² / g, particularly preferably 10 to 30 m ² / g, most preferably 10 m ² / g or more and less than 30 m ² / g. Titanium oxide having a specific surface area in the above range has a large amount of exposure of the highly active surface and can exhibit excellent photocatalytic ability. The specific surface area of titanium oxide is determined by a nitrogen adsorption method.

  When the specific surface area of titanium oxide is less than the above range, the ability to adsorb reactants tends to decrease and the photocatalytic ability tends to decrease. On the other hand, when the specific surface area of titanium oxide exceeds the above range, the separability between excited electrons and holes tends to decrease, and the photocatalytic ability tends to decrease.

  In the photocatalyst of the present invention, the iron compound supported on the titanium oxide surface may be in any state such as iron ion, iron simple substance, iron salt, iron oxide, iron hydroxide, iron complex and the like.

  In the photocatalyst of the present invention, the content of iron element based on titanium oxide is, for example, 50 to 2000 ppm, and the upper limit is preferably 1500 ppm, more preferably 1000 ppm, still more preferably 800 ppm, particularly preferably 500 ppm, and most preferably 400 ppm. Particularly preferred is 300 ppm. The lower limit is preferably 100 ppm, more preferably 150 ppm, and particularly preferably 200 ppm. When the iron element content exceeds the above range, excited electrons do not act effectively, and the photocatalytic ability tends to decrease. On the other hand, when the iron element content is below the above range, the visible light responsiveness tends to decrease.

  Further, the chlorine atom content on the basis of titanium oxide in the photocatalyst of the present invention is, for example, 50 to 1400 ppm, and the upper limit is preferably 1200 ppm, more preferably 1000 ppm, still more preferably 900 ppm, particularly preferably 800 ppm, and most preferably. Is 750 ppm, particularly preferably 700 ppm. The lower limit is preferably 100 ppm, more preferably 200 ppm, still more preferably 400 ppm, particularly preferably 500 ppm, most preferably 550 ppm, particularly preferably 600 ppm. When the chlorine atom content is outside the above range, the catalytic activity tends to decrease.

  Furthermore, in the photocatalyst of the present invention, the iron element content / chlorine atom content (weight ratio) based on titanium oxide is, for example, 1.50 or less, preferably 1.40 or less, more preferably 1.0 or less, and more. It is preferably 0.8 or less, particularly preferably 0.6 or less, most preferably 0.5 or less, and particularly preferably 0.4 or less. The lower limit is, for example, 0.05, preferably 0.1, particularly preferably 0.2, most preferably 0.25, and particularly preferably 0.3.

  Furthermore, although the photocatalyst of the present invention may carry a transition metal compound other than the iron compound, the ratio of the iron compound to the total amount of the transition metal compound supported on the titanium oxide (in terms of metal element) is, for example, 80% by weight. Above, preferably 90% by weight or more, particularly preferably 95% by weight or more. That is, the ratio of the transition metal compound other than the iron compound to the total amount of the transition metal compound supported on titanium oxide (in terms of metal element) is, for example, 20% by weight or less, preferably 10% by weight or less, particularly preferably 5% by weight. It is as follows. If the amount of other transition metal compound supported exceeds the above range, the effect of the present invention tends to be difficult to obtain.

[Method for producing photocatalyst]
The photocatalyst of the present invention has, for example, a crystal type in which rutile type and anatase type are mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)), and the ratio of titanium oxide The surface area (according to the BET method measurement) can be produced through a step of supporting iron (III) chloride on titanium oxide having a range of 7 to 55 m ² / g.

  The titanium oxide used for the production of the photocatalyst of the present invention has a crystal type in which rutile type and anatase type are mixed, and the mixing ratio of the rutile type and the anatase type (the former / the latter (X-ray diffraction peak intensity ratio)) is 30/70 to 95/5, preferably 35/65 to 90/10, particularly preferably 40/60 to 85/15, most preferably more than 50/50 and not more than 85/15, particularly preferably 50 / It exceeds 50 and is 80/20 or less.

  Titanium oxide having a crystal type in which a rutile type and an anatase type are mixed can be produced, for example, by a method (gas phase method) in which titanium tetrachloride is burned in a burner. In addition, the rutile type and the anatase are produced by further baking a titanium oxide having a crystal type mixed with a rutile type and an anatase type produced by a vapor phase method at a high temperature to convert a part of the anatase type into a rutile type. The mixing ratio of the mold can be adjusted.

In addition, it can be manufactured by burning anatase-type titanium oxide in the gas phase at a temperature of 500 ° C. or higher and converting a part thereof to the rutile type. By adjusting the combustion time, the rutile type and the anatase type can be produced. The ratio can be controlled. In addition, anatase type titanium oxide can be manufactured by a well-known and commonly used method (for example, methods (I) to (III) below).
(I) Method of subjecting titanium tetraisopropoxide to a thermal decomposition reaction at a temperature of 600 to 800 ° C. (gas phase method)
(II) A method of firing amorphous titanium oxide obtained by a sol-gel method at a temperature of 300 to 600 ° C. (liquid phase method)
(III) Method of hydrothermally treating titanium alkoxide at 250 to 300 ° C. in an autoclave (hydrothermal method)

  As a method of supporting iron (III) chloride on titanium oxide, for example, an impregnation method in which titanium oxide is impregnated with iron (III) chloride can be performed.

  Specifically, the impregnation can be performed by adding an aqueous iron (III) chloride solution to an aqueous suspension of titanium oxide. The iron (III) chloride concentration in the iron (III) chloride aqueous solution is, for example, about 10 to 80% by weight. The impregnation time is, for example, about 1 to 48 hours, preferably 3 to 24 hours, and particularly preferably 3 to 12 hours. By adjusting the iron (III) chloride aqueous solution concentration and the impregnation time, the iron element content and chlorine atom content of the resulting photocatalyst can be controlled.

  Furthermore, in the present invention, it is preferable to add a sacrificial agent to the system when impregnating titanium oxide with iron (III) chloride. By adding the sacrificial agent, the iron compound can be efficiently supported on the surface of the titanium oxide. As the sacrificial agent, it is preferable to use an organic compound that easily emits electrons. For example, alcohols such as methanol and ethanol; carboxylic acids such as acetic acid; ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA) And the like.

  The addition amount of the sacrificial agent can be adjusted as appropriate, and is, for example, about 0.5 to 20.0% by weight of titanium oxide, preferably 1.0 to 5.0% by weight. An excessive amount of the sacrificial agent may be used.

  In the present invention, it is preferable to irradiate excitation light when iron (III) chloride is supported (or adsorbed) on the titanium oxide surface. When irradiated with excitation light, iron ions supported on specific sites on the surface of titanium oxide are selectively peeled off, so that the reaction field of oxidation and reduction is spatially separated and the separation between excited electrons and holes This is because the recombination of excited electrons and holes and the progress of the reverse reaction are suppressed to be extremely low, so that a photocatalyst capable of exhibiting a further excellent photocatalytic ability can be obtained.

Irradiation with excitation light can be performed by irradiating light having energy equal to or higher than the band gap energy, such as ultraviolet rays. In the case of irradiating ultraviolet rays, for example, an ultraviolet exposure device such as a medium / high pressure mercury lamp, a UV laser, a UV-LED, or a black light can be used. The irradiation amount of the excitation light is, for example, about 0.1 to 300 mW / cm ² , preferably 0.5 to 100 mW / cm ² . The irradiation time of the excitation light is, for example, about 1 to 48 hours, preferably 3 to 36 hours, and particularly preferably 6 to 36 hours.

  The photocatalyst of the present invention obtained through the above steps is preferably purified by a well-known and commonly used method. In particular, the photocatalyst of the present invention obtained through the above steps is used for the electrical conduction of the supernatant liquid of the aqueous suspension. It is preferable to repeatedly wash with water until the degree becomes 300 μS / cm or less (for example, 0.5 to 300 μS / cm), preferably 250 μS / cm or less, particularly preferably 200 μS / cm or less. By washing with water until the electrical conductivity of the aqueous suspension is within the above range, impurities contained in the photocatalyst [for example, unreacted raw material (titanium compound) contained in titanium oxide, iron compound (for example, iron (III) chloride) , Iron (III) nitrate, trivalent iron compounds such as iron (III) sulfate), and reaction intermediates (for example, divalent iron compounds)] can be separated and removed, further improving the photocatalytic performance. Can be made.

  Examples of water used for the water washing include purified water, distilled water, ion exchange water, and pure water.

  As the washing treatment method, for example, dispersion in water, washing in water, and centrifugation are repeated until the electrical conductivity of the supernatant after centrifugation is within the above range, or a filtrate (or permeation through a filtration membrane) is used. Examples of the method include repeated membrane filtration until the electrical conductivity of the liquid reaches the above range. Membrane filtration includes a total amount filtration method and a cross flow method (a method in which water to be treated is flowed parallel to the filtration membrane surface and filtered on the side of the flow). In the present invention, it is particularly preferable to perform membrane filtration by the crossflow method in that the content of ionic impurities can be reduced while maintaining the crystal structure and dispersibility of the photocatalyst of the present invention.

The photocatalyst of the present invention obtained by the above method has a very excellent photocatalytic activity, and 200 mg of the photocatalyst is charged in a reaction vessel (volume: 200 mL), and the reaction is performed with methanol gas (air dilution, 800 ppm by volume). The amount of carbon dioxide produced (concentration conversion) in the reaction vessel when irradiated with light (light source: 405 nm LED, illuminance: 2.5 W / m ² ) for 24 hours at 25 ° C. with the inside of the vessel filled. For example, it is 300 volume ppm or more, preferably 400 volume ppm or more, more preferably 500 volume ppm or more, particularly preferably 650 volume ppm or more, most preferably 700 volume ppm or more, and particularly preferably 760 volume ppm or more. The upper limit is about 1000 ppm.

  The photocatalyst of the present invention has excellent responsiveness in a wide wavelength range from the ultraviolet region to the visible light region, and can exhibit excellent photocatalytic activity as described above, so that it can be used not only outdoors but also indoors and in vehicles. In an environment where the amount of ultraviolet rays is low, it can be applied to environmental purification and enhancement of functions of home appliances.

[Coating solution]
The coating liquid of this invention is used for the use which forms the coating layer containing the said photocatalyst on the said application | coating object surface by apply | coating to arbitrary application | coating objects, and contains the said photocatalyst at least. In addition to the photocatalyst, the coating liquid of the present invention can appropriately contain, for example, a binder resin, a color pigment, a dispersion medium, and the like as necessary.

  The coating liquid of the present invention can be applied by using, for example, spraying, brushing, roller, gravure printing, etc., and then dried and / or cured to form a coating layer.

[Photocatalyst coated body]
The photocatalyst-coated body of the present invention is characterized by comprising one or more coating layers containing the photocatalyst on the substrate surface.

  The thickness of the coating layer (the total thickness when it has two or more layers) is, for example, about 0.1 to 1 μm.

  Examples of the base material from the viewpoint of materials include various plastic materials [for example, olefin-based resins containing α-olefin as a monomer component such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer; polyethylene Polyester resins such as terephthalate, polyethylene naphthalate, polybutylene terephthalate; polyvinyl chloride; vinyl acetate resin; polyphenylene sulfide; amide resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); polyimide resin Polyetheretherketone, etc.], rubber materials (eg, natural rubber, synthetic rubber, silicon rubber, etc.), metal materials (eg, aluminum, copper, iron, stainless steel, etc.), paper materials (eg, paper, paper-like substances, etc.) ), Woody materials (eg, Materials, wood boards such as MDF, plywood, etc.), fiber materials (eg, non-woven fabric, woven fabric, etc.), leather materials, inorganic materials (eg, stone, concrete, etc.), glass materials, porcelain materials, etc. be able to.

  Examples of the base material from the viewpoint of use include lenses (for example, glasses and camera lenses), prisms, vehicle members such as automobiles and railway vehicles (window glass, illumination lamp covers, rearview mirrors, etc.), building members (for example, , Outer wall materials, inner wall materials, window frames, window glass, etc.), machine components, various display devices such as traffic signs, advertising towers, sound insulation walls (for roads, railways, etc.), bridges, guardrails, tunnels, insulators, solar cells Covers, solar water heater heat collection covers, lighting fixtures, bathroom items, bathroom components (eg, mirrors, bathtubs, etc.), kitchen appliances, kitchen components (eg, kitchen panels, sinks, range hoods, exhaust fans, etc.), air conditioning, toilet articles , Articles such as toilet members (for example, toilets), antibacterial, antifungal, deodorizing, air purification, water purification, antifouling effects, and films, sheets, paper Mention may be made of the Le and the like.

  The photocatalyst-coated body of the present invention has a coating layer containing the above-mentioned photocatalyst, so that it has excellent antibacterial and antibacterial properties not only in the sunlight irradiation environment but also in a low-light environment such as an incandescent lamp and a fluorescent lamp. Effects such as mold, deodorization, air purification, water purification, and antifouling can be exhibited.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Preparation Example 1
Crystalline form in which titanium tetrachloride is burned in a burner and mixed with titanium oxide (30) [specific surface area: 45 m ² / g, mixing ratio of rutile type and anatase type (X-ray diffraction peak intensity ratio): 30/70) Has been manufactured.

Preparation Example 2
Titanium tetrachloride was burned in a burner to produce titanium oxide (50) [specific surface area: 30 m ² / g, mixing ratio of rutile type and anatase type (X-ray diffraction peak intensity ratio): 50/50].

Preparation Example 3
Titanium oxide (30) obtained in Preparation Example 1 was heated in the electric furnace at 1000 ° C. for 90 minutes in the atmosphere to obtain titanium oxide (71) [specific surface area: 20 m ² / g, mixed rutile type and anatase type. Ratio (X-ray diffraction peak intensity ratio): 71/29].

Example 1
10 g of titanium oxide (30) obtained in Preparation Example 1 and 90 g of ion-exchanged water were stirred and mixed to obtain a suspension.
To the obtained suspension, 0.15 g of an aqueous iron (III) chloride solution (iron (III) chloride concentration: 38% by weight) was added, and the mixture was stirred at 25 ° C. for 30 minutes. Thereafter, 2.3 g of methanol (corresponding to 23% by weight of titanium oxide) was added, and the mixture was further stirred for 6 hours.
Thereafter, the suspension is subjected to powder washing in which the supernatant is washed with water until the electric conductivity of the supernatant becomes 200 μS / cm or less, and a high-speed centrifugal sedimentator (centrifugal force: 20000 G, centrifugation time: 10 to 20 minutes) is used. Used to settle the powder.
The settled powder was collected and dried at 60 ° C. using a vacuum dryer to obtain a dry powder.
The obtained dry powder was ground in a mortar, and with respect to the photocatalyst (1) (Fe / titanium oxide (30), titanium oxide, iron element content: 1820 ppm, chlorine atom content: 1310 ppm, iron element content / Chlorine atom content: 1.39) was obtained.

Example 2
The photocatalyst (2) (Fe / titanium oxide) was prepared in the same manner as in Example 1 except that the titanium oxide (71) obtained in Preparation Example 3 was used instead of the titanium oxide (30) obtained in Preparation Example 1. (71), with respect to titanium oxide, iron element content: 1740 ppm, chlorine atom content: 1270 ppm, iron element content / chlorine atom content: 1.37).

Example 3
Example 1 except that an aqueous solution of iron (III) chloride and methanol were added to the suspension, followed by irradiation with ultraviolet rays (UV) for 6 hours using a 10 W black light (UV irradiation amount: 10 mW / cm ² ). Similarly, with respect to photocatalyst (3) (Fe / titanium oxide (30) (UV), titanium oxide), iron element content: 230 ppm, chlorine atom content: 650 ppm, iron element content / chlorine atom content: 0.35) was obtained.

Example 4
Instead of the titanium oxide (30) obtained in Preparation Example 1, a suspension was obtained using the titanium oxide (50) obtained in Preparation Example 2, and the resulting suspension was subjected to iron chloride (III ) Photocatalyst (4) (4) (Addition of aqueous solution and methanol in the same manner as in Example 1 except that ultraviolet rays (UV) were irradiated for 6 hours using a 10 W black light (UV irradiation amount: 10 mW / cm ² ). With respect to Fe / titanium oxide (50) (UV) and titanium oxide, iron element content: 220 ppm, chlorine atom content: 630 ppm, iron element content / chlorine atom content: 0.35) were obtained.

Example 5
Instead of the titanium oxide (30) obtained in Preparation Example 1, a suspension was obtained using the titanium oxide (71) obtained in Preparation Example 3, and the resulting suspension was subjected to iron chloride (III ) Photocatalyst (5) in the same manner as in Example 1 except that after adding an aqueous solution and methanol, ultraviolet rays (UV) were irradiated for 6 hours using a 10 W black light (UV irradiation amount: 10 mW / cm ² ). With respect to Fe / titanium oxide (71) (UV) and titanium oxide, iron element content: 210 ppm, chlorine atom content: 620 ppm, iron element content / chlorine atom content: 0.34) were obtained.

Comparative Example 1
Instead of the titanium oxide (30) obtained in Preparation Example 1, titanium oxide (20) (titanium oxide having a crystal form in which rutile type and anatase type are mixed, mixing ratio of rutile type and anatase type (X-ray diffraction peak) Intensity ratio): 20/80, specific surface area: 50 m ² / g, trade name “AEROXIDE TiO ₂ P25” manufactured by Nippon Aerosil Co., Ltd.), and photocatalyst (7) (7) With respect to Fe / titanium oxide (20) and titanium oxide, iron element content: 2120 ppm, chlorine atom content: 1500 ppm, iron element content / chlorine atom content: 1.41).

<Measurement method of iron element content>
The iron element content of the photocatalyst was measured by the following method.
About 20 mg of the photocatalyst was precisely weighed, 1 mL of sulfuric acid was added, and then dissolved by heating on a sand bath. After dissolution, a small amount of ultrapure water is added and refluxed, and this is made up to 20 mL in an IWAKI PP container, further 0.2 μm filtered to prepare a sample, and this is analyzed by ICP emission spectrometry ( ICP emission analyzer: manufactured by Rigaku Corporation, CIROS).
Moreover, the sample obtained by carrying out similarly to the above except having not added a photocatalyst was used as a blank. As the standard solution for the calibration curve, a solution prepared by diluting a mixed standard solution XSTC-22 for ICP-MS manufactured by SPEX with an aqueous sulfuric acid solution having the same concentration was used.

<Method for measuring chlorine atom content>
The chlorine atom content of the photocatalyst was measured under the following conditions.
Combustion conditions Equipment used: AQF-100 manufactured by Dia Instruments
Sample: about 20mg
Combustion program: 2
Absorbent: H ₂ O ₂ 150 ppm
Internal standard solution: Tartaric acid 5ppm
Absorbing liquid volume: 10mL
Ion chromatography conditions Equipment used: DIONEX ICS-2000 (low concentration analysis mode)
This column: AS-12
Precolumn: AG-12
Eluent: 3.0 mM K ₂ CO ₃ +0.3 mM EPM
Suppressor: ASRS (recycle mode)
Flow rate: 1.2 mL / min Detector: Conductivity detector Column temperature: 35 ° C
Injection volume: 100 μL

<Photocatalytic activity evaluation method (methanol oxidation method)>
The photocatalytic activities of the photocatalysts (1) to (7) and titanium oxide (20) were evaluated by oxidizing methanol and measuring the amount of CO ₂ produced.
That is, about 200 mg of photocatalyst was spread on a glass dish, placed in a reaction vessel (capacity: 200 mL, ANALYTIC-BARRIER, manufactured by GL Sciences Inc.), evacuated, and then methanol gas (air diluted; 800 volume ppm) ) 125 mL was blown into the reaction vessel. After the adsorption of methanol gas to the photocatalyst reached equilibrium, light irradiation (light source: 405 nm LED, illuminance: 2.5 W / m ² ) was performed at 25 ° C.
A gas chromatograph with a flame ionization detector (trade name “GC-14B”) attached with a methanizer (trade name “MT221”, manufactured by GL Science Co., Ltd.) for the CO ₂ concentration in the reaction vessel 24 hours after the start of light irradiation, A value obtained by subtracting the CO ₂ concentration in the reactor before the start of light irradiation was defined as the amount of CO ₂ produced. The results are shown in FIGS.

1 and 2, an iron compound is supported on titanium oxide having a crystal type in which rutile type and anatase type are mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)). It can be seen that the photocatalyst of the present invention is superior in catalytic activity compared to a photocatalyst obtained by supporting an iron compound on titanium oxide in which the mixing ratio of the rutile type and the anatase type is outside the above range.
Moreover, it can be seen that the mixing ratio of the rutile type and the anatase type tends to improve the catalytic activity when the content ratio of the rutile type is increased within the above range.
Furthermore, it can be seen that the photocatalyst obtained by irradiating the excitation light when the iron compound is supported has dramatically improved catalytic activity compared to the photocatalyst obtained without irradiating the excitation light.

Claims (7)

A photocatalyst having a structure in which an iron compound is supported on a titanium oxide surface, wherein the titanium oxide has a specific surface area (measured by a BET method) in a range of 7 to 55 m ² / g, and the titanium oxide has a rutile type and an anatase type. Having a crystal type mixed in a range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)). In a reaction vessel (capacity: 200 mL), 200 mg of the photocatalyst was charged, and the reaction vessel was filled with methanol gas (air dilution, 800 ppm by volume). Light irradiation was performed at 25 ° C. for 24 hours (light source: 405 nm LED). , Illuminance: 2.5 W / m ² ) The photocatalyst according to claim 1, wherein the amount of carbon dioxide produced (concentration conversion) in the reaction vessel is 300 ppm by volume or more.   The iron element content on the basis of titanium oxide is 50 to 2000 ppm, the chlorine atom content is 50 to 1400 ppm, and the iron element content / chlorine atom content (weight ratio) is 1.50 or less. Or the photocatalyst of 2. The rutile type and anatase type have crystal types mixed in the range of 30/70 to 95/5 (the former / the latter (X-ray diffraction peak intensity ratio)), and the specific surface area (according to BET method measurement) is 7 to 55 m. ^A method for producing a photocatalyst, wherein the photocatalyst according to any one of claims 1 to 3 is obtained through a step of supporting iron (III) chloride on titanium oxide in a range of ² / g.   The method for producing a photocatalyst according to claim 4, wherein the excitation light is irradiated when iron (III) chloride is supported on titanium oxide.   The coating liquid containing the photocatalyst of any one of Claims 1-3.   The photocatalyst coating body provided with the coating layer containing the photocatalyst of any one of Claims 1-3 on the base-material surface.

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