JP2018094505A - Visible light responsive hybrid photocatalyst, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst at a low cost, the photocatalyst being capable of removing volatile organic compounds in a space effectively and continually even in an environment without UV light and free of use limitation caused by coloring.SOLUTION: A visible light responsive hybrid photocatalyst is formed by coating zeolite with iron-ion-carrying titanium oxide particles having iron ions carried by titanium oxide. The photocatalyst contains a complex oxide having an interface of the zeolite and iron-ion-carrying titanium oxide particles fused.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a visible light responsive hybrid photocatalyst in which a visible light responsive photocatalyst and a zeolite are combined and a method for producing the same.

  It is widely known that a photocatalyst decomposes organic substances by its photocatalytic action. The photocatalytic action is used to decompose and remove trace amounts of organic substances contained in the air from the living space, and studies are being made to prevent allergic diseases such as so-called “sick house syndrome”.

Titanium oxide is widely known as a typical photocatalyst. Titanium oxide does not exhibit photocatalytic action unless it is irradiated with ultraviolet rays. Therefore, it is necessary to have sunlight rays containing ultraviolet rays or special light sources that generate ultraviolet rays.
In recent years, research has been conducted on visible light responsive photocatalysts (hereinafter referred to as visible light responsive photocatalysts) that do not require ultraviolet light and exhibit photocatalytic action by visible light.
Nitrogen-doped titanium oxide, platinum compound-modified titanium oxide, platinum-modified tungsten oxide, copper ion-supported tungsten oxide, iron ion-supported titanium oxide, copper ion-supported titanium oxide, etc. have been reported as visible light responsive photocatalysts and have already been put into practical use. Some things are.
Non-Patent Document 1 reports that iron aqua complex has high activity of decomposing volatile organic compounds. Titanium oxide modified with iron aqua complex is regarded as synonymous with “iron ion-supported titanium oxide”.

Patent Document 1 discloses a hybrid photocatalyst obtained by combining a copper ion-supporting tungsten oxide that is a visible light responsive photocatalyst and a zeolite that is an adsorbent by a mechanochemical reaction. A hybrid photocatalyst is a composite of a zeolite and a photocatalyst, and has both a zeolite adsorption function and a photocatalyst decomposition function. In the hybrid photocatalyst, the zeolite quickly adsorbs the organic matter to be treated, and the photocatalyst decomposes the organic matter adsorbed on the zeolite, so that the adsorption performance of the zeolite can be maintained semipermanently without reaching adsorption saturation. it can.
Patent Document 1 proposes a technique for enhancing the activity of a photocatalyst and realizing rapid decomposition of an organic substance by combining copper ion-supported tungsten oxide and zeolite by a mechanochemical reaction.
According to the hybrid photocatalyst of Patent Document 1, volatile organic compounds in the space can be continuously removed with high ability in an indoor environment where ultraviolet rays do not reach.

However, the hybrid photocatalyst of Patent Document 1 has the following problems.
The hybrid photocatalyst of Patent Document 1 is obtained by combining a visible light responsive photocatalyst containing tungsten oxide as a component and zeolite by a mechanochemical reaction, and has a yellowish color due to coloring derived from tungsten oxide. For this reason, there is a problem that there is a restriction that it cannot be applied to uses that are required to be colorless, and there is a problem in that the application range is limited, which is inconvenient.
Moreover, the hybrid photocatalyst of Patent Document 1 is a technique premised on the use of a grade of tungsten oxide that can be used as a highly sensitive photocatalyst. However, a grade of tungsten oxide that can be used as a high-sensitivity photocatalyst is expensive, and thus there is a problem that it becomes an obstacle to application to popular products.

JP 2014-193433 A

J. et al. Phys. Chem. , C 2010, 114, 16481

  The present invention has been made in view of such circumstances, and the present invention solves the problems of the prior art described above, and the volatile organic compound in the space even in an environment such as a room or in a vehicle where ultraviolet rays do not reach. It is an object of the present invention to provide a photocatalyst that can be continuously removed with high ability and that does not cause application restrictions due to coloring at low cost.

As a result of intensive studies, the present inventors have solved the above problems by making a mechanochemical reaction between the iron ion-carrying titanium oxide particles and zeolite to form a visible light responsive hybrid photocatalyst. The present inventors have found that a photocatalyst that can continuously remove a volatile organic compound in a space with high ability and that does not cause a use limitation due to coloring can be provided at low cost, and has completed the present invention.
The present invention provides the following [1] to [9].
[1] Visible including a composite oxide in which zeolite is coated with iron ion-supported titanium oxide particles in which iron ions are supported on titanium oxide, and an interface between the zeolite and the iron ion-supported titanium oxide particles is fused. Photoresponsive hybrid photocatalyst.
[2] The visible light responsive hybrid photocatalyst according to [1], wherein a coverage of the iron ion-supported titanium oxide particles on the surface is 30 to 300%.
[3] The visible light responsive hybrid photocatalyst according to [1] or [2], wherein an average primary particle diameter of the iron ion-supported titanium oxide particles is 10 to 800 nm.
[4] The visible light responsive hybrid photocatalyst according to any one of [1] to [3], wherein the titanium oxide has a specific surface area of 1 to 200 m ² / g.
[5] The visible light responsive hybrid photocatalyst according to any one of [1] to [4], wherein the zeolite is at least one selected from Y-type and ZSM-5 type.
[6] The visible light responsive hybrid photocatalyst according to any one of [1] to [5], wherein the zeolite has a pore diameter of 4 to 10 mm.
[7] A method for producing a visible light responsive hybrid photocatalyst comprising a reaction step of mechanochemical reaction of iron ion-carrying titanium oxide particles and zeolite.
[8] The method for producing a visible light responsive hybrid photocatalyst according to [7], wherein the added energy of the mechanochemical reaction is 0.1 to 300 kW.
[9] The method according to [7] or [8], further comprising a pretreatment step of performing a mechanical pretreatment performed on the iron ion-supported titanium oxide particles by a method similar to a mechanochemical reaction before the reaction step. Of producing a visible light responsive hybrid photocatalyst.

Visible light responsive type comprising a composite oxide in which zeolite is coated with iron ion-supported titanium oxide particles in which iron ions are supported on titanium oxide, and an interface between the zeolite and the iron ion-supported titanium oxide particles is fused. By using a hybrid photocatalyst, a photocatalyst that can continuously remove volatile organic compounds in the space with high capacity even in environments where ultraviolet rays do not reach, and that does not cause application restrictions due to coloring, is low cost. Can be realized.
According to the present invention, it is possible to obtain a visible light responsive photocatalyst exhibiting higher catalytic activity than simple mixing of iron ion-supported titanium oxide particles alone and zeolite as an adsorbent.

It is a graph which shows the result (CO2 generation | occurrence | production change with time) of the photolysis experiment of an Example and Comparative Examples 1 and _2. FIG. It is a graph which shows the result (Acetaldehyde decrease time-dependent change) of the adsorption experiment of an Example and Comparative Examples 1 and 2. FIG. It is Example 1 (mechanochemical coverage 100% Y-type _{(SiO 2 / Al 2 O 3} = 5) + Fe / TiO 2) SEM photograph (Figure in scale 1 [mu] m). 2 is an SEM photograph of Example 1 (scale 2 μm in the figure). 2 is a SEM photograph of Example 1 (scale 500 nm in the figure). Comparative Example 1 is a (simple mixing coverage 100% Y-type _{(SiO 2 / Al 2 O 3} = 5) + Fe / TiO 2) SEM photograph (Figure in scale 2 [mu] m).

  The visible light responsive hybrid photocatalyst of the present invention is obtained by a mechanochemical reaction between iron ion-supported titanium oxide particles and zeolite. According to the present invention, by causing mechanochemical reaction between iron ion-supported titanium oxide particles and zeolite, a synergistic effect of the photocatalyst and zeolite can be exhibited and high photocatalytic activity can be obtained.

[Iron-ion-supported titanium oxide particles]
The visible light responsive hybrid photocatalyst of the present invention has a visible light responsive photocatalytic ability by including iron ion-supported titanium oxide particles.
The iron ion-supporting titanium oxide particles can be obtained, for example, by dispersing titanium oxide in a liquid in which iron ions are dissolved and bringing the iron ions into contact with titanium oxide.

The titanium oxide used in the present invention includes crystalline rutile type titanium oxide.
In the present invention, crystalline rutile type titanium oxide means that the full width at half maximum of the strongest diffraction peak corresponding to rutile type titanium oxide is 0 in the X-ray diffraction pattern in which the diffraction line intensity with respect to the diffraction angle 2θ by Cu-Kα ray is plotted. It means titanium oxide of 65 degrees or less.
When the full width at half maximum is larger than 0.65 degrees, the crystallinity is deteriorated, and the decomposition activity of the volatile organic compound under visible light irradiation is deteriorated. From this viewpoint, the full width at half maximum is preferably 0.60 degrees or less, more preferably 0.50 degrees or less, still more preferably 0.40 degrees or less, and still more preferably 0.35 degrees or less. is there.
The content of crystalline rutile-type titanium oxide in titanium oxide (hereinafter sometimes referred to as “rutile degree”) is preferably 15 mol% or more. When the content is 15 mol% or more, the resulting iron ion-carrying titanium oxide has sufficient decomposition activity for volatile organic compounds under visible light irradiation. From this viewpoint, the rutile ratio is more preferably 18 mol% or more, still more preferably 50 mol% or more, and still more preferably 90 mol% or more. This rutile ratio is a value measured by XRD as described later.
From the above viewpoint, the content of anatase-type titanium oxide in titanium oxide (hereinafter sometimes referred to as “anataseization rate”) is preferably small, and the anatase conversion rate is preferably less than 85 mol%, more preferably. Is less than 82 mol%, more preferably less than 50 mol%, even more preferably less than 10 mol%, still more preferably less than 7 mol%, and even more preferably 0 mol% (i.e. Does not contain anatase-type titanium oxide). This anatase rate is also a value measured by XRD, like the rutile rate.
From the above viewpoint, the content of brookite-type titanium oxide in titanium oxide (hereinafter sometimes referred to as “brookite conversion rate”) is preferably small, and the brookite conversion rate is preferably less than 85 mol%, more preferably Is less than 82 mol%, more preferably less than 50 mol%, even more preferably less than 10 mol%, still more preferably less than 7 mol%, and even more preferably 0 mol% (i.e. It does not contain brookite type titanium oxide). This brookite conversion rate is also a value measured by XRD, like the rutile conversion rate.

The specific surface area of titanium oxide is preferably 1 to 200 m ² / g.
When it is 1 m ² / g or more, the specific surface area is large, so that the contact frequency with the volatile organic compound increases, and the resulting volatile organic compound decomposability of the iron ion-supported titanium oxide is excellent.
When it is 200 m ² / g or less, the handleability is excellent. From these viewpoints, the specific surface area of titanium oxide is more preferably 3 to 100 m ² / g, still more preferably 4 to 70 m ² / g, and particularly preferably 8 to 50 m ² / g. Here, the specific surface area is a value measured by the BET method by nitrogen adsorption.

Titanium oxide includes those produced by a vapor phase method and those produced by a liquid phase method, and any of them can be used, but titanium oxide produced by a vapor phase method is more preferable.
The vapor phase method is a method of obtaining titanium oxide by vapor phase reaction with oxygen using titanium tetrachloride as a raw material. Titanium oxide obtained by the vapor phase method has a uniform particle size and at the same time has high crystallinity because it passes through a high-temperature process during production. As a result, the obtained iron and titanium-containing composition has good antiviral properties in light and dark places, organic compound decomposability and antibacterial properties.
On the other hand, the liquid phase method is a method for obtaining titanium oxide by hydrolyzing or neutralizing a liquid in which a titanium oxide raw material such as titanium chloride or titanyl sulfate is dissolved. Titanium oxide produced by the liquid phase method tends to have a low rutile crystallinity and a large specific surface area. In this case, the titanium oxide having the optimum crystallinity and specific surface area may be obtained by firing or the like. The gas phase method is more preferable because it takes time and effort.
As titanium oxide, it is more advantageous to use commercially available titanium oxide as it is in view of the catalyst preparation step.
The average primary particle diameter of titanium oxide is preferably 10 nm to 800 nm, more preferably 30 nm to 500 nm, and still more preferably 50 nm to 250 nm. Here, the average particle diameter is a value obtained from the BET specific surface area assuming that the primary particles are true spheres.

  As a method of obtaining titanium ion-supported titanium oxide by modifying titanium oxide with iron ions (iron ion-supporting step), for example, titanium oxide powder is formed from iron trivalent salt (iron chloride, iron sulfate, iron nitrate, etc.), preferably chloride. A method of adding iron (III) to a polar solvent solution (preferably an aqueous solution), mixing, drying, and supporting iron ions on the surface of titanium oxide can be used.

The amount of iron ions supported is preferably 0.001 to 0.2 parts by mass, more preferably 0.002 to 0.1 parts by mass, and 0.003 to 0 parts per 100 parts by mass of titanium oxide in terms of metal (Fe). 0.08 parts by mass is more preferable.
When the supported amount is 0.001 part by mass or more, the photocatalytic ability when used as a photocatalyst is improved. By being 0.2 parts by mass or less, aggregation of iron ions hardly occurs and it is possible to prevent the photocatalytic ability from being lowered when used as a photocatalyst.

  The average primary particle size of the iron ion-supported titanium oxide particles is preferably 10 nm to 800 nm, more preferably 30 nm to 500 nm, and still more preferably 50 nm to 250 nm. Here, the average particle diameter is a value obtained from the BET specific surface area assuming that the primary particles are true spheres.

[Zeolite]
The zeolite used in the present invention is not particularly limited, but faujasite, A-type zeolite, L-type zeolite, zeolite β, mordenite, chabasite, ferrierite, clinoptilolite, ZSM-5 type zeolite ZSM-11 type zeolite, ZSM-22 type zeolite, ZSM-48 type zeolite. Examples of the faujasite include X-type zeolite, Y-type zeolite, and ultra-stabilized Y-type zeolite (Ultra Stable Y; USY). The zeolite may be natural or synthetic. Among these, ZSM-5 type zeolite and Y type zeolite are preferable.

The silica / alumina ratio (SiO ₂ / Al ₂ O ₃ molar ratio) of the zeolite used in the present invention is not particularly limited but is usually determined by the type of zeolite. For example, 2-1000 is preferable, 2-900 is more preferable, and 5-800 is still more preferable.

The effective pore diameter of the zeolite used in the present invention is, for example, preferably 3 to 20 mm, more preferably 3 to 15 mm, and still more preferably 4 to 10 mm. The effective pore diameter is a pore diameter measured by a constant volume gas adsorption method. Examples of the adsorption gas used in the constant capacity gas adsorption method include N ₂ , CO ₂ , CH ₄ , and H ₂ .
The specific surface area of the zeolite used in the present invention is not particularly limited, but is preferably 200 m ² / g or more, more preferably 250 m ² / g or more, more preferably 300 m ² / g or more, and still more preferably 400 m ² / g or more. . The upper limit of the specific surface area is not particularly limited, but is, for example, 1000 m ² / g. The specific surface area is determined by a nitrogen adsorption BET method (for zeolites having an effective pore diameter of 3 mm or less, the helium adsorption BET method).

  Zeolites generally contain metal cations or protons. Any metal can be used as the metal contained in the zeolite used in the present invention, and examples thereof include alkali metals, alkaline earth metals, and transition metals. More specifically, sodium, potassium, calcium, magnesium, Examples include copper and zinc.

  From the viewpoint of use in decomposing organic substances, it is preferable to use hydrophobized zeolite. Examples of the hydrophobizing treatment include a method in which zeolite and a silane compound such as tetraalkoxysilane are brought into contact with each other.

  The average particle size of the zeolite is preferably 0.1 to 50 μm, more preferably 0.3 to 30 μm, still more preferably 0.3 to 10 μm.

[Reaction process]
The method for producing a hybrid photocatalyst of the present invention includes a step (hereinafter, also referred to as “reaction step”) of causing mechanochemical reaction between iron ion-supported titanium oxide particles and zeolite. In the production method of the present invention, prior to the reaction step, a mechanical pretreatment is performed on the iron ion-supported titanium oxide particles from the viewpoint of smoothing the mechanochemical reaction and protecting the reactor (hereinafter referred to as “ It is preferable to have a pretreatment step.
In mechanochemical reaction, mechanical particles such as friction and compression in the process of pulverizing solid materials are added to a plurality of different material particles, and high energy generated locally is used to bond different particles at the molecular level. This refers to chemical reactions such as crystallization reaction, solid solution reaction, and phase transition reaction that create composite fine particles.

The method of the mechanochemical reaction in the reaction step is not particularly limited, and examples thereof include a compression shear treatment method, a high-speed impact treatment method, and a mixed shear friction method, and among these, the compression shear treatment method is preferable.
Specifically, the compression shearing method has a rotor with a large number of blades installed inside the casing, and when the rotor rotates at high speed, impact compression, friction, and shear are applied to the particles introduced inside. It is preferable to use an apparatus that applies a mechanical action such as force to perform surface treatment. The apparatus is usually called a mechanical particle compounding apparatus, a precision fine mixing machine, or the like. Examples of commercially available products include Mechano-Fusion System AMS (manufactured by Hosokawa Micron), Nobilta NOB-130 (manufactured by Hosokawa Micron), and Theta. A composer (manufactured by Deoksugaku Kosakusha) is listed. For example, the mechanofusion system causes mechanochemical reaction by compressing particles with an inner piece on the inner wall of a high-speed rotating container and applying strong shear at a gap.

  In the mechanochemical reaction, the mixing amount of the iron ion-supported titanium oxide particles with respect to 100 parts by mass of the zeolite can be appropriately set according to the target coverage, but for example, 1 to 1000 parts by mass is preferable, and 2 to 500 parts by mass. Part is more preferable, and 3-400 parts by mass is still more preferable.

The additional energy of the mechanochemical reaction can be appropriately selected depending on the scale of the mechanical particle compounding apparatus, etc., in order to maintain the visible light responsive photocatalytic activity of the iron ion-supported titanium oxide particles and support them on zeolite. 1 kw to 300 kw is preferable, and 0.5 kw to 200 kw is more preferable. The added energy means the power of the motor in the composite device or the like.
The rotational speed in the mechanochemical reaction can be appropriately set according to the range of the added energy, but is preferably 500 to 8000 rpm, more preferably 1000 to 6000 rpm, and still more preferably 1000 to 4000 rpm.
The treatment time in the mechanochemical reaction can be appropriately set according to the range of the added energy, but is preferably 0.5 to 60 minutes, more preferably 1 to 30 minutes, and further preferably 1 to 15 minutes.

[Pretreatment process]
As a pretreatment method, the photocatalyst can be mechanically treated in the same manner as the mechanochemical reaction.
The added energy in the pretreatment can be appropriately selected depending on the scale of a mechanical particle composite device or the like, preferably 0.1 kw to 300 kw, more preferably 0.5 kw to 200 kw.
The rotation speed in the pretreatment can be appropriately set according to the range of the added energy, but is preferably 500 to 8000 rpm, more preferably 1000 to 6000 rpm, and still more preferably 1000 to 4000 rpm.
The treatment time in the pretreatment can be appropriately set according to the range of the added energy, but is preferably 0.5 to 60 minutes, more preferably 1 to 30 minutes, and further preferably 1 to 15 minutes.
In addition to the smooth mechanochemical reaction when the pretreatment process is performed, the rotating part of the mechanical particle composite device is polished by the zeolite, and the constituent metal components of the composite device are mixed into the target product. Can be prevented.

[Visible light-responsive hybrid photocatalyst]
By the above mechanochemical reaction, a visible light responsive hybrid photocatalyst of iron ion-supported titanium oxide particles and zeolite is obtained. In the hybrid photocatalyst, the interface between the iron ion-supported titanium oxide particles and the zeolite is fused.
The coverage in the obtained visible light responsive hybrid photocatalyst is preferably 30 to 300%, more preferably 50 to 250%, and still more preferably 50 to 150%.
In addition, a coverage here means the coverage area ratio of the photocatalyst with respect to a zeolite surface area. According to the mechanochemical reaction, in addition to covering the entire surface with respect to the zeolite surface area, the coverage is 100%, and by further coating the photocatalyst on the coated photocatalyst, the coverage is 200%. A coverage of over% can be achieved.

The visible light responsive hybrid photocatalyst of the present invention can obtain high photocatalytic activity by irradiating visible light of 400 nm or more by complexing iron ion-supported titanium oxide particles and zeolite.
The use of the visible light responsive hybrid photocatalyst is not particularly limited, but can be applied to various fields such as a deodorant, an antifouling paint, an antibacterial agent, and a hydrogen generating photocatalyst.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the following Example.

About the titanium oxide raw material used by an Example and a comparative example, the property was measured as follows.
<Titanium oxide raw material>
(BET specific surface area)
The BET specific surface area of the titanium oxide raw material was measured using a fully automatic BET specific surface area measuring device “Macsorb, HM model-1208” manufactured by Mountec Co., Ltd.

(Rutyl content (rutile ratio) and crystallinity (full width at half maximum) in titanium oxide raw material)
The content (rutile ratio) and crystallinity (full width at half maximum) of rutile titanium oxide in the titanium oxide raw material were measured by a powder X-ray diffraction method.
That is, with respect to the dried titanium oxide raw material, “X'pertPRO” manufactured by PANalytical was used as a measuring device, a copper target was used, a Cu-Kα1 wire was used, a tube voltage of 45 kV, a tube current of 40 mA, a measurement range 2θ = 20. X-ray diffraction measurement was performed under the conditions of -100 deg, sampling width 0.0167 deg, and scanning speed 3.3 deg / min.
The peak height (Hr) corresponding to the rutile crystal, the peak height (Hb) corresponding to the brookite crystal, and the peak height (Ha) corresponding to the anatase crystal are obtained. The content (rutile ratio) of rutile-type titanium oxide in the inside was determined.
Rutile conversion rate (mol%) = {Hr / (Ha + Hb + Hr)} × 100
In addition, the content of anatase-type titanium oxide (anatase conversion rate) and the content of brookite-type titanium oxide (brookite conversion rate) in titanium oxide were determined by the following calculation formulas.
Anatase conversion rate (mol%) = {Ha / (Ha + Hb + Hr)} × 100
Brookite conversion rate (mol%) = {Hb / (Ha + Hb + Hr)} × 100
In the X-ray diffraction pattern obtained by the X-ray diffraction measurement, the strongest diffraction peak corresponding to rutile titanium oxide was selected, and the full width at half maximum was measured.

(Average primary particle size)
The average primary particle diameter (DBET) (nm) is determined by the specific surface area S of titanium oxide according to the BET one-point method.
(M ² / g) is measured and the following formula DBET = 6000 / (S × ρ)
Calculate from Here, ρ represents the density (g / cm ³ ) of titanium oxide.
The measurement results of the titanium oxide raw materials used in Examples and Comparative Examples are shown below.
BET specific surface area 10m ² / g
Rutile conversion rate 95.9 mol%
Anatase rate 4.1 mol%
Brookite conversion rate 0 mol%
Full width at half maximum 0.18 degree average primary particle size 150 nm

In the following Examples and Comparative Examples 1 and 2, photolysis experiments and adsorption experiments were conducted by the following methods. The purpose of the photolysis experiment and the adsorption experiment is to examine the visible light photocatalytic activity of the obtained iron and titanium-containing composition.
Moreover, the scanning electron micrograph was image | photographed with the following method. The scanning electron micrograph is taken for the purpose of observing the surface structure of the obtained iron and titanium-containing composition.
[Photolysis experiment]
The photolysis experiment for examining the visible light photocatalytic activity was carried out by the following method.
0.1 g of the catalyst prepared in Examples and Comparative Examples was placed in a petri dish having an inner diameter of 27 mm, a small amount of water was added and dispersed by applying ultrasonic waves, and dried in a 120 ° C. drier.
The petri dish was placed in a 500 ml glass chamber, the inside of the chamber was replaced with synthetic air, and the cock was closed.
An acetaldehyde standard gas and a small amount of water were injected into the chamber, and the acetaldehyde concentration in the chamber was 500 ppm and the humidity was 50% RH.
After being placed in a dark place for 1 hour and confirming adsorption in the dark place, light (xenon light source, L42 filter (λ> 400 nm, 100,000 lux)) was irradiated, and the CO ₂ concentration was measured with a gas chromatograph until a certain time.

[Adsorption experiment]
The adsorption experiment for examining the visible light photocatalytic activity was conducted by the following method.
The sample preparation method was the same as the photolysis experiment except that the aldehyde concentration was measured by gas chromatography every 5 hours in the dark.

[Scanning electron micrograph]
The scanning electron micrograph was taken by the following method.
About the prepared catalyst, a high resolution scanning electron microscope / SEM (Hitachi High-Technologies Corporation S-5200) was applied to an acceleration voltage of 3 kV, a magnification of 20 to 450 K, and a new scanning electron microscope (Hitachi High-Technologies Corporation S-5500). Images were taken at an acceleration voltage of 2 kV and a magnification of 100 to 400K.

(Production Example 1: Preparation of iron ion-supported titanium oxide)
Titanium oxide (TiO _2, manufactured by Showa Denko KK, super Thailand Titania (R) F-10) powder 300g iron (III) chloride aqueous solution 4L (0.05 part by weight equivalent as Fe with respect to _TiO 2 100 parts by weight) Added to. Next, after heat treatment at 60 ° C. for 24 hours with stirring, it was washed and collected by suction filtration, dried at 120 ° C. for one day and night, pulverized in an agate mortar, and 0.05 mass parts of iron ions were supported. An iron ion-supported titanium oxide powder (Fe / TiO ₂ ) was obtained. The average primary particle diameter of the obtained Fe / TiO ₂ was 250 nm.
Here, the quantification of iron ions was measured by dissolving Fe / TiO ₂ in an HF aqueous solution by microwave irradiation and analyzing the solution by inductively coupled plasma (ICP).

(Example)
Fe / TiO ₂ of Production Example 1 was added to a mechanical particle composite device (manufactured by Hosokawa Micron Corporation, trade name: NOB130) so that the coverage of the zeolite surface was 100%, and treated at 2000 rpm for 1 minute. Then, a predetermined amount of SiO ₂ / Al ₂ O ₃ = 5 (molar ratio) Y-type zeolite (manufactured by UOP, average particle diameter of 3 μm, pore diameter of 9 mm, BET specific surface area of 765 m ² / g) was charged at 2000 rpm. Then, a mechanochemical reaction was performed for 3 kw for 10 minutes to obtain a visible light responsive hybrid photocatalyst. A photolysis experiment and an adsorption experiment were conducted, and the evaluation results are shown in Tables 1 and 2.

(Comparative Example 1)
Fe / TiO ₂ of Production Example 1 and the Y-type zeolite used in the examples were collected in a mortar so as to have the same ratio as the 100% coverage shown in Table 1, and pulverized and mixed, and Fe / TiO ₂ and zeolite were simply mixed. Was prepared. A photolysis experiment and an adsorption experiment were conducted, and the evaluation results are shown in Tables 1 and 2.

(Comparative Example 2)
Using Fe / TiO ₂ of Production Example 1, a photolysis experiment and an adsorption experiment were performed, and the evaluation results are shown in Tables 1 and 2.

When the mechanochemical and simple mixture were compared, the initial CO ₂ generation rate was improved in the hybrid photocatalyst by mechanochemical reaction (Table 1 and FIG. 1). Moreover, the effect was confirmed in adsorption | suction of the acetaldehyde of the zeolite in a dark place (Table 2 and FIG. 2).
These results indicate that the volatile organic compound (here, acetaldehyde) can be quickly removed from the space by complexing with zeolite (Example 1). Further, it is shown that the acetaldehyde is rapidly transferred from the zeolite to the photocatalyst by the hybridization by mechanochemical reaction (Example 1), and the decomposition of the acetaldehyde to CO ₂ by the photocatalyst is rapidly progressing.
Although the same phenomenon can be confirmed even with simple mixing (Comparative Example 1), the decomposition by the photocatalyst is clearly delayed as compared with the product using the mechanochemical reaction (Example 1). This suggests that it takes time for the acetaldehyde adsorbed on the zeolite to move to the photocatalyst.
When only a visible light responsive photocatalyst was used (Comparative Example 2), acetaldehyde was decomposed, but it was confirmed that it takes time for adsorption in the dark.

SEM photograph confirms that the mechanochemical reaction has uniformly dispersed Fe / TiO ₂ on the zeolite surface and fused the interface with Fe / TiO ₂ on the zeolite surface to form a complex oxide. (FIGS. 3-5). 3 to 5, small photocatalyst particles (Fe / TiO ₂ ) are dispersed on the surface of a large zeolite, and a state in which the zeolite and the photocatalyst particles (Fe / TiO ₂ ) are separately scattered is not observed.
On the other hand, in the case of simple mixing, formation of complex oxide was not confirmed, and it was confirmed that zeolite 1 and photocatalyst particles (Fe / TiO ₂ ) 2 aggregated and separated and existed as separate clusters. (Fig. 6)

The visible light responsive hybrid photocatalyst of the present invention obtained by combining iron ion-supported titanium oxide particles and zeolite exhibits high photocatalytic activity when irradiated with visible light of 400 nm or more. For this reason, the visible light responsive hybrid photocatalyst of the present invention is used for deodorant, antifouling paint, antibacterial agent, and hydrogen generation in an environment (such as indoors or in a car) where visible light not containing ultraviolet rays is used as a light source. Applications are expected in various fields such as photocatalysts.
Further, since the visible light responsive hybrid photocatalyst of the present invention is colorless, it is expected to be applied to a wider range of fields without being restricted by the use due to the conventional coloring.

1 Zeolite 2 Photocatalyst particles

Claims (9)

  Visible light responsive type comprising a composite oxide in which zeolite is coated with iron ion-supported titanium oxide particles in which iron ions are supported on titanium oxide, and an interface between the zeolite and the iron ion-supported titanium oxide particles is fused. Hybrid photocatalyst.   The visible light responsive hybrid photocatalyst according to claim 1, wherein a coverage of the iron ion-supported titanium oxide particles is 30 to 300%.   The visible light responsive hybrid photocatalyst according to claim 1 or 2, wherein an average primary particle diameter of the iron ion-supporting titanium oxide particles is 10 to 800 nm. The visible light responsive hybrid photocatalyst according to claim 1, wherein the titanium oxide has a specific surface area of 1 to 200 m ² / g.   The visible light responsive hybrid photocatalyst according to any one of claims 1 to 4, wherein the zeolite is at least one selected from a Y type and a ZSM-5 type.   The visible light responsive hybrid photocatalyst according to any one of claims 1 to 5, wherein the zeolite has a pore diameter of 4 to 10 mm.   A method for producing a visible light responsive hybrid photocatalyst, comprising a reaction step of mechanochemical reaction of iron ion-supported titanium oxide particles and zeolite.   The method for producing a visible light responsive hybrid photocatalyst according to claim 7, wherein the added energy of the mechanochemical reaction is 0.1 to 300 kW.   The visible light response type according to claim 7 or 8, further comprising a pretreatment step of performing a mechanical pretreatment on the iron ion-supported titanium oxide particles by a method similar to a mechanochemical reaction before the reaction step. A method for producing a hybrid photocatalyst.