JP2003335521A - Titanium oxide, photocatalyst body and photocatalyst body coating agent using the titanium oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide titanium oxide exhibiting high photocatalytic action by visible light irradiation, a photocatalyst body and a photocatalyst body coating agent using the titanium oxide. <P>SOLUTION: This titanium oxide has an index X expressed by formula (1): X=A/B of 0.97 or less, wherein A is a mean value of half value width measured at a first and a second measurement, and B is that measured at a third and a fourth measurement in the total four times of measurement of half value width of a peak of titanium existing between 458 to 460 eV of bonding energy of titanium oxide by an X-ray photoelectron spectroscopy. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to titanium oxide, a photocatalyst using the same, and a photocatalyst coating agent. In detail, by irradiating with visible light, a high photocatalytic action is expressed, decomposition of NOx in the atmosphere, decomposition and removal of malodorous substances and molds in living spaces and working spaces, or organic solvents and pesticides in water, The present invention relates to a photocatalyst capable of decomposing and removing environmental pollutants such as a surfactant, titanium oxide as a catalyst component thereof, and a photocatalyst coating agent as a coating agent.

[0002]

2. Description of the Related Art When a semiconductor is irradiated with ultraviolet rays, electrons having a strong reducing action and holes having a strong oxidizing action are generated, and a molecular species in contact with the semiconductor is decomposed by the redox action. Such an action is called a photocatalytic action, and by utilizing this photocatalytic action, decomposition of NOx in the atmosphere, decomposition and removal of malodorous substances and molds in living spaces and working spaces, or organic solvents and pesticides in water, It is possible to decompose and remove environmental pollutants such as surfactants. Titanium oxide has attracted attention as a substance having a photocatalytic action, and photocatalysts made of titanium oxide are commercially available. Examples of commercially available products include
P-25 (trade name: manufactured by Degussa) may be mentioned.

However, the above-mentioned photocatalyst made of titanium oxide does not have a sufficient photocatalytic action when irradiated with visible light.

[0004]

The object of the present invention is to provide a photocatalyst having a high photocatalytic activity by irradiation with visible light, titanium oxide as its catalyst component, and a photocatalyst coating agent as a coating agent. Especially.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that titanium oxide as a catalyst component suitable for a photocatalyst body having a high photocatalytic action by irradiation with visible light is used. Heading out, the present invention has been completed.

That is, according to the present invention, the full width at half maximum of the titanium peak between 458 eV and 460 eV of the binding energy of titanium oxide is measured by X-ray photoelectron spectroscopy, and the first and second titanium peaks are measured. The average value of the full width at half maximum is A, the average value of the full width at half maximum of the third and fourth titanium peaks is B, and the index X represented by the following formula (I) is calculated from the full width at half maximum A and B. Titanium oxide having 0.97 or less. X = B / A (I)

Further, the present invention is a photocatalyst body containing the above-mentioned titanium oxide as a catalyst component.

Furthermore, the present invention is a photocatalyst coating agent comprising the above titanium oxide and a solvent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The titanium oxide (TiO ₂ ) of the present invention has a binding energy of titanium oxide of 458 eV to 460 eV measured by X-ray photoelectron spectroscopy.
The average value of the half-value widths of the first and second titanium peaks when the half-value width of the titanium peak between the
The average value of the half-value widths of the third and fourth titanium peaks is B, and the index X represented by the formula (I) from the half-value widths A and B is 0.97 or less, preferably 0.93. It is the following. In the present invention, the full width at half maximum of titanium peak is measured by XPS-7000 manufactured by Rigaku Denki Kogyo Co., Ltd. (X-ray source: M
gKα 8kV 30mA (narrow scan), pas
s E = 10 eV, step E = 0.04 eV), the peak of titanium (Ti) required for 60 seconds per measurement is measured twice, and then the peak of oxygen (O) required for 56 seconds per measurement is measured. Measurement is performed twice, and then the carbon (C) peak that requires 80 seconds for each measurement is measured twice.
Titanium (T
The peak of i) is measured twice, and the time from the start to the end of the total of eight measurements should be within 10 minutes without exposing to the atmosphere during and between the peak measurements. To do.

When the index X of the titanium oxide is larger than 0.97, the titanium oxide does not have a sufficient photocatalytic action for irradiation with visible light.

Further, since the titanium oxide can exhibit a higher photocatalytic action against irradiation of visible light, the ultraviolet visible spectrophotometer is used to measure the ultraviolet visible diffuse reflectance spectrum using barium sulfate as a standard white plate and an integrating sphere. When you measured
When the integral value of the absorbance of the spectrum at the wavelength of 220 nm to 800 nm is C and the integral value of the absorbance of the spectrum at the wavelength of 400 nm to 800 nm is D, the index Y represented by the following formula (II) is 0.14. The above is preferable,
0.16 or more is more preferable. Y = D / C (II) The integrated value of the absorbance is the ultraviolet-visible diffuse reflectance spectrum in which the vertical axis is the absorbance and the horizontal axis is the wavelength, and the horizontal axis and the diffuse reflectance spectrum are within a specified wavelength range. Refers to the area enclosed by and.

When the index Y of the titanium oxide is less than 0.14, the titanium oxide does not have a sufficient photocatalytic action for irradiation with visible light.

Further, since the titanium oxide of the present invention can obtain a higher photocatalytic activity upon irradiation with visible light, it is preferable that the crystal structure of titanium oxide is anatase type.

The shape of the titanium oxide of the present invention differs depending on the method of use and is not unique, but examples thereof include particulate and fibrous shapes. Further, the titanium oxide may be mixed with an inorganic compound within a range that does not impair the photocatalytic activity due to irradiation with visible light, or may be mixed and then heat treated to form a mixture. Examples of the inorganic compound include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), magnesia (MgO) and zinc oxide (ZnO).

The method for producing titanium oxide of the present invention includes:
For example, a method using a so-called chemical reaction, in which at least one type of substance is allowed to recombine between itself and another substance to cause a reaction, and a substance different from the original substance is generated, is used. Specifically, hydrolysis method, uniform precipitation method, thermal decomposition method, coprecipitation method, solid phase reaction method, ion exchange method, complex polymerization method, hydrothermal synthesis method, calcination synthesis method, liquid phase deposition method, impregnation method, etc. The usual methods for synthesizing ceramic materials include, among others, titanium oxide having an excellent photocatalytic action against irradiation with visible light can be obtained.
Application of hydrolysis method is recommended.

More specifically, a method of mixing a titanium compound with water to hydrolyze it, a method of mixing a titanium compound with water vapor to hydrolyze, and the like may be used. Furthermore, by performing the hydrolysis in an alkaline atmosphere, titanium oxide having an excellent photocatalytic action against irradiation with visible light can be obtained. When the hydrolysis is performed in an alkaline atmosphere, for example, in addition to ammonia, amide compounds such as urea and formamide, amidine compounds such as acetamidine, amine compounds such as triethanolamine and hexamethylenetetramine, etc. The method of hydrolyzing in the presence of a substance or the like that produces an alkaline component can be mentioned, and among others, the method of hydrolyzing in the presence of ammonia or urea is recommended. As the titanium compound, titanium trichloride, titanium tetrachloride, titanium sulfate, titanyl sulfate, titanium alkoxide and the like are used.

The photocatalyst of the present invention is characterized by containing the above-mentioned titanium oxide as a catalyst component. The photocatalyst sufficiently expresses the high photocatalytic activity of the titanium oxide of the present invention, decomposes NOx in the atmosphere, decomposes and removes malodorous substances and molds in living spaces and working spaces, or uses organic solvents and pesticides in water. It enables the decomposition and removal of environmental pollutants such as surfactants.

The photocatalyst body is obtained, for example, by adding a molding aid to particulate titanium oxide and then extruding the sheet-like photocatalyst body, or by entanglement of fibrous titanium oxide and organic fibers. Examples thereof include a sheet-shaped photocatalyst body, a photocatalyst body obtained by coating or coating titanium oxide on a metal or resin support. In addition, in order to improve the mechanical strength and moldability of the photocatalyst, in addition to the titanium oxide of the present invention, an inorganic compound, a polymer resin, a molding aid, a binder, an antistatic agent, an adsorbent Etc. may be added. Examples of the inorganic compound include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), magnesia (MgO), zinc oxide (ZnO), and titanium oxide having photocatalytic activity with respect to ultraviolet irradiation. Is mentioned.

When the photocatalyst is used, for example,
The photocatalyst and the liquid to be treated or the gas to be treated may be placed in a glass container that transmits visible light, and the photocatalyst may be irradiated with visible light having a wavelength of 430 nm or more using a light source. still,
Of course, it is also possible to irradiate the ultraviolet rays used in the usual photocatalytic reaction. The irradiation time may be appropriately selected depending on the intensity of the light source, the initial concentration of the substance to be treated in the liquid to be treated, the target concentration and the like.

The light source is not limited as long as it irradiates visible light having a wavelength of 430 nm or more, or ultraviolet light used in ordinary photocatalytic reactions. For example, sun rays, fluorescent lamps, halogens. A lamp, a black light, a xenon lamp, a mercury lamp, etc. can be applied. Of course, it may be used in a state where light having a wavelength of less than 400 nm, such as ultraviolet rays, which is harmful to the human body, is blocked.

The photocatalyst coating agent of the present invention is characterized by containing the above-mentioned titanium oxide and a solvent. The photocatalyst coating agent facilitates application of titanium oxide to building materials, automobile materials, etc., or coating of building materials, automobile materials, etc. with titanium oxide, and high photocatalytic activity for building materials, automobile materials, etc. It is possible to give. The solvent is preferably a solvent which does not remain in titanium oxide after being coated or evaporated after coating, for example, water,
Examples thereof include hydrochloric acid, alcohols, ketones and the like.

Examples of the method for producing the photocatalyst coating agent include a method in which titanium oxide is dispersed in water to form a slurry, and a method in which titanium oxide is peptized with an acid or the like. At the time of the dispersion, a dispersant may be added if necessary.

The titanium oxide of the present invention has a wavelength of 430 nm.
It has a high photocatalytic action by the above irradiation of visible light. Further, the photocatalyst of the present invention, due to the high photocatalytic activity of titanium oxide, decomposes NOx in the atmosphere, decomposes and removes malodorous substances and molds in living spaces and working spaces, or uses organic solvents, pesticides, and interfaces in water. It makes it possible to decompose and remove environmental pollutants such as activators. Furthermore, the photocatalyst coating agent of the present invention facilitates the application of titanium oxide to building materials, automobile materials, etc., or the coating of building materials, automobile materials, etc. with titanium oxide, and thus to the building materials, automobile materials, etc. It is possible to give a high photocatalytic action.

Further, the photocatalyst of the present invention (including a photocatalyst consisting only of titanium oxide), a building material coated with a photocatalyst coating, etc., decomposes or oxidizes and removes various chemical substances by its photocatalytic action. It is possible. Examples of the chemical substance include environmental pollutants or microorganisms such as bacteria, radioactive bacteria, fungi, algae, molds and the like.

Examples of the environmental pollutants include endocrine disrupting chemicals called environmental hormones, organic halogen compounds, organic phosphorus compounds, other organic compounds, nitrogen compounds, sulfur compounds, cyan compounds, chromium compounds and other inorganic compounds. can give. As endocrine disrupting substances, alkylphenols such as nonylphenol and octylphenol, biphenyls such as bisphenol A, phthalic acids such as butylbenzyl phthalate and dibutyl phthalate,
In addition to pesticides such as DDT (dichlorodiphenyltrichloroethane), methoxychlor and endosulfan, organic chlorine compounds such as dioxin and PCB (polychlorinated biphenyl) are listed. Examples of organic halogen compounds other than endocrine disrupting chemicals include freon, trihalomethane, trichloroethylene, tetrachloroethylene and the like. Organic substances other than endocrine disrupting chemicals, organic halogen compounds, and organic phosphorus compounds include hydrocarbons such as surfactants and oils, aldehydes, mercaptans, alcohols, amines, aminos, proteins, etc. Can be mentioned. Examples of nitrogen compounds include ammonia and nitrogen oxides.

[0026]

EXAMPLES The photolytic action of acetaldehyde will be described in Examples, but the present invention is not limited to these Examples. The characteristics of titanium oxide and photocatalyst were evaluated by the following methods.

X-ray photoelectron spectroscopy (XPS): measured by the following procedure using XPS-7000 manufactured by Rigaku Denki Kogyo. 1. The peak of titanium (Ti), which requires 60 seconds per measurement, is measured twice. (1st integration) 2. The oxygen (O) peak, which requires 56 seconds per measurement, is measured twice. 3. The carbon (C) peak, which requires 80 seconds per measurement, is measured twice. 4. The peak of titanium (Ti), which requires 60 seconds per measurement, is measured twice. (Second integration) These operations were performed in the order of 1 to 4, and the time required to complete all the operations was within 10 minutes. The measurement conditions were as follows. X-ray source: MgKα 8 kV 30 mA (narrow scan) pass E = 10 eV step E = 0.04 eV

Ultraviolet-visible diffuse reflectance spectrum: The visible-visible diffuse reflectance spectrum was measured using an ultraviolet-visible spectrophotometric system UV-2500PC manufactured by Shimadzu Corporation using an integrating sphere having barium sulfate as a standard white plate.

Crystal structure: An X-ray diffractometer RAD-IIA manufactured by Rigaku Denki Kogyo KK was used.

Example 1 100 g of 20% titanium trichloride solution (manufactured by Wako Pure Chemical Industries: special grade)
Was stirred in a 300 mL flask under a nitrogen atmosphere, and while cooling with ice water, 141 g of 25% ammonia water (manufactured by Wako Pure Chemical Industries: special grade) was added dropwise over about 30 minutes for hydrolysis. The obtained sample was filtered, washed and dried. Then 40 in air
The particles were calcined at 0 ° C. for 1 hour to obtain yellow colored particulate titanium oxide. The obtained titanium oxide had a crystal structure of anatase type. Table 1 shows the results of XPS measurement of titanium oxide.
Table 2 shows the results of the UV-visible diffuse reflectance spectrum measurement.

Next, a glass petri dish having a diameter of about 5 cm was placed in a closed glass reaction vessel made of Pyrex (registered trademark) (diameter: 8 cm × height: 10 cm, capacity: about 0.5 liter) and placed on the petri dish. Then, a photocatalyst body consisting of only yellow-colored particulate titanium oxide was placed. The inside of the reaction vessel was filled with a mixed gas of oxygen and nitrogen in a volume ratio of 1: 4, acetaldehyde of about 38 μmol was enclosed, and irradiation with visible light having a wavelength of 430 nm or more was performed. The photocatalytic effect of acetaldehyde on the photocatalyst was measured by gas chromatography (Shimadzu Corporation, using the concentration of carbon dioxide, which is an oxidative decomposition product of acetaldehyde produced by irradiation.
It was evaluated by measuring using a column: Porapak Q, a carrier gas: helium). In addition, a 500 W Xenon lamp (manufactured by Ushio Inc .: Lamp House UI-502Q, Lamp UXL-500D) equipped with an ultraviolet light cut filter (Toshiba glass color glass filter: product name Y-45) having the spectral characteristics shown in FIG. 1 is used as a light source. , Lighting device XB-50101AA-A) was used. The generation rate of carbon dioxide is 23.4 μmol / hr per 1 g of catalyst.
Met.

Example 2 300 mL of 25 g of titanium tetrachloride (manufactured by Wako Pure Chemical Industries, Ltd.)
While stirring in an air atmosphere in a flask and cooling with ice water, 36 g of 25% ammonia water (manufactured by Wako Pure Chemical Industries: special grade) was added dropwise over about 5 minutes for hydrolysis. The obtained sample was filtered, washed and dried. Then, it was baked in air at 400 ° C. for 1 hour to obtain white particulate titanium oxide. The obtained titanium oxide had a crystal structure of anatase type. Titanium oxide X
The results of PS measurement are shown in Table 1, and the results of ultraviolet-visible diffuse reflection spectrum measurement are shown in Table 2.

Next, the same procedure as in Example 1 was carried out except that a photocatalyst body consisting only of particulate titanium oxide colored in yellow was replaced with a photocatalyst body consisting solely of white particulate titanium oxide. It was The production rate of carbon dioxide at this time was 0.75 μmol / hr per 1 g of the catalyst.

Comparative Example 1 In place of the photocatalyst consisting of only the particulate titanium oxide colored yellow in Example 1, the commercially available P-25 (trade name, manufactured by Degussa, crystal type: anatase type and rutile type) was used. Example 1 was repeated except that the photocatalyst was used. The production rate of carbon dioxide at this time was 0.3 μmol / hr per 1 g of the catalyst. The results of XPS measurement of P-25 are shown in Table 1, and the results of UV-visible diffuse reflectance spectrum measurement are shown in Table 2.

The photocatalyst of the present invention has a higher oxidative decomposition action (photocatalytic action) with respect to the oxidative decomposition of acetaldehyde by irradiation with visible light having a wavelength of 430 nm or more, as compared with the commercially available photocatalyst made of titanium oxide.

[0036]

As described above, according to the present invention, the wavelength is 4
Provided is titanium oxide having a high photocatalytic action when irradiated with visible light having a wavelength of 30 nm or more. In addition, the present invention provides a photocatalyst containing titanium oxide, which has a high photocatalytic action upon irradiation with visible light having a wavelength of 430 nm or more, as a catalyst component, and decomposes NOx in the atmosphere, in living spaces and working spaces. It is possible to decompose and remove malodorous substances and molds, or to decompose and remove environmental pollutants such as organic solvents, pesticides and surfactants in water. Furthermore, the present invention provides a photocatalyst coating agent containing titanium oxide and a solvent, coating titanium oxide on a building material, automobile material, etc., or coating a building material, automobile material, etc. with titanium oxide. It is possible to easily and impart a high photocatalytic action to building materials, automobile materials and the like.

[0037]

[Table 1]

[0038]

[Table 2]

[Brief description of drawings]

FIG. 1 is a wavelength-transmittance diagram showing spectral characteristics of an ultraviolet cut filter attached to a light source used in an example.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Miaki Takeuchi             Sumitomo Chemical 5-1, Soukai-cho, Niihama-shi, Ehime             Industry Co., Ltd. F-term (reference) 4G047 CA02 CB05 CC03 CD03 CD07                 4G069 BA04A BA04B BA48A BB08C                       EA08 EC22Y EC27 FB08                 4J038 HA211 KA04

Claims (3)

[Claims] 1. The half-value widths of the first and second titanium peaks when the half-value width of the titanium peak between 458 eV and 460 eV of the binding energy of titanium oxide is measured four times by X-ray photoelectron spectroscopy. And the average value of the half-value widths of the third and fourth titanium peaks is B, and the index X shown by the following formula (I) is 0.9.
Titanium oxide of 7 or less. X = B / A (I) 2. A photocatalyst body containing the titanium oxide according to claim 1 as a catalyst component. 3. A photocatalyst coating agent comprising the titanium oxide according to claim 1 and a solvent.