Visible light responsive material and method for producing the same

Description: TECHNICAL FIELD [Detailed description of the invention]

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INDUSTRIAL APPLICABILITY The present invention relates to a visible light responsive material and a method for producing the same. Furthermore, the present invention relates to a sterilization, algae-proofing, antifungal and / or antifouling method, a water purification method, and a method for reducing nitrogen oxides contained in the atmosphere using the visible light responsive material of the present invention. The visible light responsive material of the present invention is useful as a photocatalyst, an optical sensor, a material for a photovoltaic cell, a light antifouling material, a photohydrophilic material, a photobacterial material, and the like.

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[Conventional Technology] It is known that antibacterial tiles, self-cleaning building materials, superhydrophilic materials, deodorant / deodorant materials, water purification, cancer treatment, etc. can be performed using a photocatalyst made of anatase-type titanium dioxide. (Hikari Clean Revolution (Akira Fujishima et al.)), Various applications are being actively developed. Specifically, for example, WO94 / 11092 discloses an air treatment method using a photocatalyst under indoor lighting. Japanese Patent Application Laid-Open No. 7-102678 discloses a method for preventing nosocomial infections using a photocatalyst. Japanese Patent Application Laid-Open No. 8-67835 and Japanese Patent Application Laid-Open No. 8-164334 disclose antibacterial coating materials. Further, WO96 / 29375 discloses a superhydrophilic material.

However, anatase-type titanium dioxide requires ultraviolet rays of 400 nm or less as excitation light. On the other hand, sunlight and artificial light, which can be excitation light sources, contain an order of magnitude more visible light than ultraviolet light. However, unfortunately, in the photocatalyst made of titanium dioxide, visible light is hardly available, and it is very inefficient from the viewpoint of energy conversion efficiency. And this inefficiency was a big barrier to practical use.

Therefore, the development of a photocatalyst that can use visible light is gradually being carried out. For example, Japanese Patent Application Laid-Open No. 10-146530 discloses a titanium oxide-based photocatalyst in which the O / Ti atomic number ratio in a layer deeper than the surface is smaller than the O / Ti atomic number ratio in the surface. This photocatalyst is formed by heating a complex of titanium alkoxide and a chelating agent (for example, acetylacetone) at about 500 ° C. in an oxidizing atmosphere. However, in this method, titanium alkoxide and a chelating agent (for example, acetylacetone) are used, which increases the production cost, and the O / Ti atomic number ratio needs to be different between the surface and the inside. There is a problem that it is very difficult to control. Further, in the examples, it is described that the activity was obtained by irradiation with light of 420 nm or more, but the obtained activity was very low and was not practically usable.

Further, a catalyst made of titanium dioxide having a stable oxygen defect and having activity under visible light irradiation is known (WO00 / 10706). This photocatalyst is obtained, for example, by using ST-01 manufactured by Ishihara Sangyo Co., Ltd., which is known as an ultraviolet photocatalyst, as a raw material and treating it with plasma such as hydrogen or argon. ST-01 manufactured by Ishihara Sangyo mainly has activity against ultraviolet rays, but as shown in Table 5 (powder F), it is considerably lower than the activity against ultraviolet rays, but visible light up to around 420 nm. Shows activity against. However, there is substantially no activity above 470 nm. On the other hand, the photocatalyst described in WO00 / 10706 can photooxidize NO not only with light having a wavelength of about 420 nm but also with light having a wavelength of about 600 nm, and can be said to be a truly visible photocatalyst.

However, since plasma treatment is used, a decompression system is required. As a result, there is a problem that it is not easy to process powders, particularly uniform mixing, and it is not suitable for continuous production. By the way, as a general method for producing anatas-type titanium oxide by a wet method, (1) a method for hydrolyzing a titanium-containing solution such as titanyl sulfate or titanium sulfate, and (2) a method for hydrolyzing an organic titanium compound such as titanium alkoxide. (3) A method of calcining a precipitate obtained by a neutralization method or a hydrolysis method of a titanium halide solution such as titanium tetrachloride is known. As mentioned above, there have been attempts to develop visible photocatalysts using titanium alkoxide, but visible photocatalysts and visible light responsive materials made from titanium sulfate or titanium chloride, which are inexpensive as raw materials, have been known so far. Not.

Therefore, an object of the present invention is to provide a novel photoresponsive material which can be manufactured at low cost and which also responds to visible light, and a method for manufacturing the same.

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According to the present invention, the g value is measured in ESR of titanium oxide containing at least anatase-type titanium oxide and measured in vacuum under irradiation with light having a wavelength of 420 nm or more at 77 K. A main signal with a g value of 2.004 to 2.007 and two sub-signals with g values of 1.985 to 1.986 and 2.024 were observed, and these three signals were in vacuum, 77K, in the dark. The present invention relates to a visible light responsive material characterized in that it is observed in a minute amount or is not substantially observed in the above.

Further, the present invention is a method of heating amorphous or incomplete crystalline titanium oxide and / or titanium hydroxide (raw titanium compound) in the presence of ammonia or a derivative thereof, and is a method for producing a material. The present invention relates to a method for producing a visible light responsive material, which comprises ending the heating at a time when the absorption of light at a wavelength of 450 nm is larger than the absorption of light at a wavelength of 450 nm of the raw material titanium compound.

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BEST MODE FOR CARRYING OUT THE INVENTION The visible light responsive material of the present invention is titanium oxide containing at least anatase type titanium oxide, and has a g value of 2. A main signal with 004 to 2.007 (the strongest signal) and two sub-signals with g values of 1.985 to 1.986 and 2.024 (the signal with lower intensity than the main signal) were observed. It is a thing. Furthermore, in the visible light responsive material of the present invention, the above three signals (main signal and two sub-signals) are observed minutely or substantially not observed in vacuum at 77K and in the dark. It is a feature. In the present invention, the light having a wavelength of 420 nm or more used for ESR is a filter (for example, 500 W) that cuts light having a wavelength shorter than 420 nm from a high-pressure mercury lamp (for example, 500 W) as described in Examples. It is light obtained by passing through L-42). Further, in the visible light responsive material of the present invention, light having a wavelength of 455 nm or more at 77 K in vacuum (a filter (GG455) that cuts light from an Xe lamp (for example, 150 W) having a wavelength shorter than 455 nm). Even in the ESR measured under the irradiation of light obtained by transmitting the light, the main signal (the signal with the strongest intensity) having a g value of 2.004 to 2.007 and the g value of 1.985 to 1. Two sub-signals, 986 and 2.024 (signals with lower intensity than the main signal) may be observed.

The visible photocatalyst made of titanium dioxide having a stable oxygen defect described in WO00 / 10706 described above also has a specific ESR spectrum. However, the ESR spectrum of the visible photocatalyst described in WO00 / 10706 has only signals with a g value of 2.003 to 2.004 in ESR measured in vacuum at 77K in the dark. It is different from the spectrum shown by the visible light responsive material of the present invention.

The visible light responsive material of the present invention is preferably titanium oxide containing anatase-type titanium oxide as a main component, and may also contain amorphous titanium oxide. Alternatively, rutile-type titanium oxide may be further contained. Further, the anatase-type titanium oxide does not necessarily have high crystallinity. Further, in the titanium oxide constituting the visible light responsive material of the present invention, titanium and oxygen can have an indefinite ratio, and specifically, the amount of oxygen with respect to titanium is the stoichiometric ratio of titanium dioxide. It may be less than (theoretical value 2.00). The titanium oxide in the visible light responsive material of the present invention has, for example, a molar ratio of oxygen to titanium of less than 2.00, for example, 1.00 to 1.99, or 1.50 to 1.99. Can be done. The molar ratio of oxygen to titanium in titanium oxide in the visible light responsive material of the present invention can be measured using, for example, X-ray photoelectron spectroscopy.

A typical spectrum of ESR measured at 77K in vacuum of the visible light responsive material of the present invention is shown in FIG. In the figure, the upper part is a spectrum under darkness, and the middle part is a spectrum under irradiation of light having a wavelength of 420 nm or more (light of a mercury lamp having a wavelength of less than 420 nm is cut off). The lower part is the spectrum when the light of the mercury lamp is irradiated without cutting off the light of less than 420 nm without cutting off. The upper, middle, and lower stages are all the results of measurement under the same gain (GAIN).

In the upper spectrum of FIG. 1, the main signals having g values of 2.004 to 2.007 are observed minutely, but the g values are 1.985 to 1.986 and 2.024. The two sub-signals are virtually non-observable. Furthermore, when the upper spectrum and the middle spectrum of FIG. 1 are compared, it is clear that in the middle spectrum, the main signal having a g value of 2.004 to 2.007 and the g value of 1.985 to 1.986 are apparent. The two sub-signals, and 2.024, are significantly more intense in the upper spectrum. Further, as is clear from comparing the spectra in the middle and lower rows of FIG. 1, the main signals having g values of 2.004 to 2.007 and the g values of 1.985 to 1.986 and 2.024. The intensities of the two sub-signals are substantially the same whether or not the irradiation light contains light of less than 420 nm.

Further, in the visible light responsive material of the present invention, as shown in FIG. 2, the main signal having a g value of 2.004 to 2.007 is observed minutely in vacuum, at room temperature, and in the dark. However, the two sub-signals with g values of 1.985 to 1.986 and 2.024 are substantially absent. Further, in the ESR under the irradiation of light having a wavelength of 420 nm or more and the light irradiation of a mercury lamp that does not cut off the light of less than 420 nm in vacuum and at room temperature, the above three signals may be measured. Understand. In FIG. 2, the upper part is a spectrum under darkness, and the middle part is a spectrum under irradiation of light having a wavelength of 420 nm or more (light of a mercury lamp having a wavelength of less than 420 nm is cut off). The lower part is the spectrum when the light of the mercury lamp is irradiated without cutting off the light of less than 420 nm. The upper, middle, and lower stages are all the results of measurement under the same gain (GAIN).

Further, it is presumed that the three signals in the visible light responsive material of the present invention are attributed to radicals caused by hole capture. This is clear from the ESR spectrum in the isopropanol (electron donor molecule) atmosphere and the ESR spectrum in the air atmosphere (oxygen in the air is the electron acceptor molecule), as also shown in the examples.

The visible light responsive material of the present invention has a g value of 2.009 to 2.010 in addition to the above signal when measured in vacuum under irradiation with light having a wavelength of 420 nm or more at 77 K. It can also have a sub-signal that is. The sub-signals having a g value of 2.009 to 2.010 are shown in the ESR spectrum in the middle of FIG.

As described above, the visible light responsive material of the present invention has a characteristic ESR signal, but at the same time, it also has a coloring, for example, the reflectance to light having a wavelength of 600 nm. When 1 (or 100%) is set, the reflectance for light having a wavelength of 450 nm is 0.85 (or 85%) or less, preferably 0.80 (or 80%) or less, more preferably 0.70 (or 70). %) Can be less than or equal to. The greater the coloring, the stronger the visible light response activity tends to be. The reflectance here is the result measured by a spectrophotometer as shown in Examples described later. Although the reflectance can be measured with a color analyzer, a spectrophotometer is used to evaluate the reflectance because it is excellent in terms of accuracy.

As described above, the visible light responsive material of the present invention has a characteristic ESR signal, but in addition, as shown concretely and in detail in the examples, it is in the visible light region. It has NO oxidizing activity with respect to light. Specifically, NO oxidation activity is exhibited by irradiating visible light having a wavelength of at least 520 nm or less. In a more preferable material, NO oxidative activity is exhibited by irradiating with visible light having a wavelength of 570 nm or less.

The visible light responsive material of the present invention can be produced from amorphous or incomplete crystalline titanium oxide (including titanium hydroxide) and / or titanium hydroxide. This raw material titanium compound can be obtained by a wet method such as a sulfuric acid method or a chloride method. More specifically, the raw material titanium compound can be obtained by hydrolyzing titanium chloride or titanium sulfate with ammonium hydroxide. Alternatively, the raw material titanium compound can be obtained by hydrolyzing titanium alkoxide with water, or can be obtained by hydrolyzing titanium alkoxide with an aqueous solution of ammonium hydroxide. However, from the viewpoint of low raw material price, in industrial production, it is preferably obtained by hydrolyzing titanium chloride or titanium sulfate with ammonium hydroxide. Therefore, a case where titanium chloride or titanium sulfate is hydrolyzed with ammonium hydroxide will be described below.

The hydrolysis is carried out, for example, by continuously or intermittently adding an aqueous solution of ammonium hydroxide to an aqueous solution of titanium chloride or an aqueous solution of titanium sulfate, or by continuously adding an aqueous solution of titanium chloride or an aqueous solution of titanium sulfate to an aqueous solution of ammonium hydroxide. It can be added intermittently or intermittently. The concentrations of the titanium chloride aqueous solution, the titanium sulfate aqueous solution and the ammonium hydroxide aqueous solution can be appropriately determined. It is appropriate to carry out this hydrolysis by adjusting the amount of ammonium hydroxide added so that the final pH of the reaction solution becomes alkaline of 8 or more. The titanium chloride may be titanium trichloride, titanium tetrachloride, or the like, and a mixture thereof may be used. The above hydrolysis can be carried out, for example, at a temperature in the range of 0 ° C. to 100 ° C., preferably 20 ° C. to 80 ° C., but the hydrolysis at room temperature has relatively low crystalline or non-crystalline dioxide. It may be preferable from the viewpoint that titanium can be obtained.

0022. The hydrolyzate of titanium chloride or titanium sulfate with ammonium hydroxide is preferably used as a raw material titanium compound after being washed with water or an aqueous solution of ammonium hydroxide. Washing of the hydrolyzate with water or an aqueous solution of ammonium hydroxide is carried out, for example, by filtering a reaction solution containing the hydrolyzate and further passing water or an aqueous solution of ammonium hydroxide through the hydrolyzate obtained as a filtrate. be able to. This method is preferable because it is easy to operate because water or an aqueous ammonium hydroxide solution may be added to the filtered hydrolyzate as it is and filtered. In addition to the above, washing of the hydrolyzate with water or an aqueous solution of ammonium hydroxide is performed by, for example, resuspending the filtrate of the hydrolyzate in water or an aqueous solution of ammonium hydroxide and filtering the obtained suspension. It can be carried out. Washing with water or an aqueous solution of ammonium hydroxide can be carried out so that the residual amount of ammonium salts such as ammonium chloride or ammonium sulfate produced during hydrolysis is reduced to an appropriate amount, and can be carried out a plurality of times. Further, as the amorphous or incomplete crystalline titanium dioxide, a commercially available product may be used, for example, incomplete crystalline titanium dioxide such as ST-01 or C-02 manufactured by Ishihara Sangyo. You may.

In the production method of the present invention, a raw material titanium compound such as amorphous or incomplete crystalline titanium oxide is heated in the presence of ammonia or a derivative thereof. Ammonia may be a liquid or a gas. When ammonia gas is used, the raw material titanium compound is heated in an ammonia gas atmosphere. Examples of the ammonia derivative include ammonium salts such as ammonium hydroxide and ammonium chloride. For example, the raw material titanium compound is heated in the coexistence of ammonium hydroxide and ammonium chloride.

0024 Heating of the raw material titanium compound in the presence of ammonia or a derivative thereof is such that the heating is terminated when the absorption of light at a wavelength of 450 nm of the material produced by heating is greater than the absorption of light at a wavelength of 450 nm of the raw material titanium compound. To be done by. Normally, the raw material titanium compound is white, and the absorption of light at a wavelength of 450 nm is around 10%. On the other hand, when the raw material titanium compound is heated in the presence of ammonia or a derivative thereof, it gradually turns yellow. However, this coloring fades after peaking at a certain point in time, and finally becomes a substance that exhibits the same level of absorption as the raw material titanium compound. Although it depends on the type of the raw material titanium compound, the type and amount of ammonia (derivative) coexisting, the heating temperature, the time, etc., the absorption of light at a wavelength of 450 nm may reach about 60% at the maximum. The characteristics of the visible light responsive material are not uniquely determined by the light absorption intensity at a wavelength of 450 nm, but are clearly visible when the light absorption at a wavelength of 450 nm is 15% or more (reflectance of 85% or less). It is a material that exhibits photoresponsiveness. Therefore, in the above heat treatment, when the reflectance for light having a wavelength of 600 nm is 1 (or 100%), the reflectance for light having a wavelength of 450 nm is 0.85 (or 85%) or less, preferably 0.80. It is preferable to set the condition to be (or 80%) or less, more preferably 0.70 (or 70%) or less. The reflectance here is the result measured by a spectrophotometer as shown in Examples described later.

The heating conditions are not necessarily specified only by the temperature, but the temperature to be used can be, for example, a temperature in the range of 250 to 550 ° C. Figures 6 to 8 show the relationship between the NOx removal (oxidation) activity and the heating temperature (heating time was 1 hour). FIG. 6 shows the removal rate of NO, and FIG. 7 shows NO.₂The production rate of, and FIG. 8 shows the NOx removal rate. (Details are shown in Example 8.) From these figures, the removal rate of NOx by light having wavelengths of 420 nm and 470 nm is relatively high when heated in the range of 300 to 450 ° C, and in the range of 325 to 425 ° C. The removal rate of NOx by light with wavelengths of 520 nm and 570 nm was found to be higher with heating in the range of 325 to 450 ° C, and higher with heating in the range of 350 to 425 ° C. You can see that. Therefore, heating in the range of 350 to 425 ° C. is most preferable in terms of high NOx removal rate in the visible light region.

Figures 9 to 11 show the relationship between the NOx removal (oxidation) activity and the heating time (heating temperature was 400 ° C.). FIG. 9 shows the removal rate of NO, and FIG. 10 shows NO.₂The production rate of, and FIG. 11 shows the NOx removal rate. (Details are shown in Example 9.) From these figures, the heating time is 30 minutes or more, preferably 1 from the viewpoint of improving the removal rate of NOx with respect to light in the visible light region having wavelengths of 520 nm and 570 nm. It's more than an hour. Further, since the NOx removal rate does not change significantly even if the heating time is longer than 1 hour, it is about 3 hours at the longest. Further, this heating can be performed under normal pressure. Further, the heating time can be appropriately determined with reference to the absorption of light at a wavelength of 450 nm of the material produced by heating.

For the above heating, a rotary kiln, a tunnel kiln, a muffle furnace or the like which are usually used in the art can be used. When individual particles of titanium oxide are agglomerated or sintered by heating, they may be crushed by a crusher if necessary.

Further, the material obtained by heating as described above can be washed with water or an aqueous solution, if necessary. This cleaning may improve the visible light responsiveness of the resulting visible light responsive material. Further, depending on the conditions, a material having good visible light responsiveness may be obtained without cleaning. When the amorphous or incomplete crystalline titanium oxide (raw material titanium compound before heating) is obtained by hydrolyzing titanium chloride with ammonium hydroxide, for example, a considerable amount of the hydrolyzate is obtained. Ammonium chloride remains, and as a result, the amorphous or incomplete crystalline titanium dioxide as described above can be converted into a visible light responsive material by heating at a predetermined temperature. However, even after heat treatment, a considerable amount of ammonium chloride may remain in the obtained material. In such a case, it may be possible to remove ammonium chloride and improve the visible light responsiveness of the visible light responsive material by washing with water or a suitable aqueous solution. For example, FIGS. 12 to 14 show a diagram showing the relationship between the number of washings and the activity of removing (oxidizing) NOx. FIG. 12 shows the removal rate of NO, and FIG. 13 shows NO.₂The production rate of, and FIG. 14 shows the NOx removal rate. (Details are shown in Example 10-1.) From these figures, NOx removal (oxidation) activity increases up to the point where the number of washings increases, and washing has the effect of improving visible light responsiveness. You can see that.

Further, in this case, in the washing of the material obtained by heating with water or an aqueous solution, the pH of the water or the aqueous solution separated from the material after washing is, for example, 3.5 or more (pH 3.5 to 7). The amount of chloride ion (when titanium chloride is used as the raw material for the hydrolyzate) or the amount of sulfate ion (titanium sulfate is the hydrolyzate) contained in the water or aqueous solution separated from the material after cleaning. When used as a raw material), it is preferable to reduce the amount. For example, FIG. 15 shows the experimental results showing the relationship between the number of washings and the pH and chlorine ion concentration of water separated from the material after washing (titanium chloride was used as a raw material for the hydrolyzate). The number of washings in FIG. 15 is for the same sample as the number of washings in FIGS. 12 to 14 above. Further, although the washing conditions are slightly different, the result of examining how much ammonium ions remain in the sample washed after heating is shown in FIG. 17 (details are shown in Example 10-2). From this result, it can be seen that the residual amount (adhesion amount) of ammonium ions is also reduced by washing.

The visible light responsive material of the present invention can be a powder or a film (thin film), and the film (thin film) can be provided on a suitable base material. To form a film (thin film), a raw material titanium compound such as amorphous or incomplete crystalline titanium oxide is coated on a base material together with an appropriate binder, if necessary, and ammonia or a derivative thereof is included in the coating film. Alternatively, it can be carried out by carrying out the heating in the presence of ammonia or a derivative thereof in the atmosphere. Alternatively, a film (thin film) can be formed by applying the visible light responsive material of the present invention in a powder state to a base material or the like.

The visible light responsive material of the present invention has silicon, aluminum, tin, zirconium, antimony, phosphorus, platinum, gold, silver, copper, iron, niobium, and tungsten on the surface and / or inside thereof depending on the application. , Tantalum and other elements and compounds containing them can also be coated, supported or doped.

By using the visible light responsive material of the present invention, it is possible to provide a sterilization, algae-proofing, fungicide-proofing, and / or antifouling method. Further, by using the visible light responsive material of the present invention, it is possible to provide a method for purifying water and a method for reducing nitrogen oxides in the atmosphere.

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[Examples] Examples of the present invention are shown below, but the present invention is not limited thereto. Reference example 1 500 g of titanium tetrachloride (manufactured by Kanto Chemical Co., Inc., special grade) was added to pure ice water (2 liters as water), stirred and dissolved to obtain an aqueous titanium tetrachloride solution. While stirring 200 g of this aqueous solution with a stirrer, about 50 ml of ammonia water (NH)₃13 wt% content) was added as soon as possible. The amount of aqueous ammonia added was adjusted so that the final pH of the aqueous solution was about 8. As a result, the aqueous solution became a white slurry. After further stirring was continued for 15 minutes, the mixture was filtered through a suction filter. The precipitate collected by filtration is 20 ml of aqueous ammonia (NH).₃The mixture was dispersed in 6 wt%), stirred with a stirrer for about 20 hours, and then suction-filtered again to obtain a white hydrolyzate. The obtained white hydrolyzate was transferred to a crucible and heated in an air at 400 ° C. for 1 hour using an electric furnace to obtain a yellow product.

The XRD measurement result of the obtained product is shown in the upper part of FIG. At the same time, the measurement result of XRD obtained by drying the white hydrolyzate at 50 ° C. is also shown in the lower part of FIG. From this result, it can be seen that the white hydrolyzate dried at 50 ° C. is amorphous, and the obtained product contains anatase-type titanium dioxide. The diffuse reflection spectrum of the obtained product and the white hydrolyzate dried at 50 ° C. was measured by a Hitachi self-recording spectrophotometer (U-3210) equipped with an integrating sphere under the following conditions. scan speed: 120nm / min, response: MEDIUM, band pass: 2.00nm, Reference: Barium Sulfate As a result, when the reflectance of the obtained product at 600 nm was 100%, the reflectance at 450 nm was 61%, whereas the white hydrolyzate dried at 50 ° C. was 600 nm. The reflectance at 450 nm was 95% when the reflectance was 100%. Further, when the reflectance of the obtained product at 700 nm was 100%, the reflectance at 450 nm was 61%, whereas the white hydrolyzate was dried at 50 ° C. at 700 nm. When the reflectance was 100%, the reflectance at 450 nm was 95%.

In addition, the ESR spectrum of the obtained product was measured. Using an ESR device, ES-RE2X, manufactured by JEOL Ltd., the measurement was performed in vacuum (0.1 Torr or less) at 77 K or at room temperature. The measurement conditions are as follows.

[Basic parameters] Measurement temperature 77K or room temperature Field 324mT ± 25mT Scanning time 4 minutes Mod. 0.1mT Receiver gain 10-100 (measurement sensitivity) Time constant 0.1 seconds RF power 0.1mW Light source High pressure mercury lamp 500W Filter L-42 (Asahi Techno Glass Co., Ltd.)

[Sample preparation] Vacuum degassing for 1 hour or more

[Calculation of g value] Mn²⁺Marker (g_mn= 1.981 (third from the high magnetic field side)) as a reference g = g_mn× H_mn/ (H_mn H) H_mn: Mn²⁺Marker magnetic field, ΔH: H_mnAmount of change in magnetic field from

In FIGS. 1 (measurement temperature 77K) and FIG. 2 (measurement temperature normal temperature), an ESR spectrum in the dark is shown in the upper row, and a filter (L) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp) is shown in the middle row. ESR spectrum measured with light irradiated through -42), with light irradiated using a 500 W high-pressure mercury lamp without using a filter (L-42) that cuts light less than 420 nm in the lower row. The measured ESR spectra are shown respectively.

Comparing the upper and middle spectra of FIG. 1, it is clear that in the middle spectrum, the main signal having a g value of 2.004 to 2.007 and the g value of 1.985 to 1.986 and 2 The two sub-signals, which are .024, were more intense in the upper spectrum. Further, when the spectra in the middle and lower rows of FIG. 1 are compared, it is clear that the main signal having a g value of 2.004 to 2.007 and the two g values of 1.985 to 1.986 and 2.024. The intensities of the sub-signals were not substantially different even if the irradiation light contained light of less than 420 nm.

Further, as shown in FIG. 2, the visible light responsive material of Reference Example 1 is also measured in ESR in the atmosphere, at room temperature, in the dark, and under light irradiation having a wavelength of 420 nm or more. It was a thing. When the white hydrolyzate is dried at 50 ° C., the main signal having a g value of 2.004 to 2.007 and the g values of 1.985 to 1.986 and 2.024 are obtained. No two sub-signals were observed under any of the ESR measurement conditions.

The measurement atmosphere in a vacuum is set to air or isopropanol, and the light is irradiated through a filter (L-42) that cuts light of less than 420 nm (using a high-pressure mercury lamp of 500 W) in the same manner as described above. The ESR spectrum was measured. The result is shown in FIG. In the figure, the upper part is the measurement result in vacuum, the middle part is in air, and the lower part is the measurement result in isopropanol. Both the main signal and the two sub-signals are the smallest in vacuum, slightly larger in isopropanol than in vacuum, but the largest in middle air. Isopropanol is an electron donor molecule, whereas oxygen in the air is an electron acceptor molecule, so the above results suggest that the three signals are attributed to radicals due to hole capture. It is a thing.

Reference Example 2 Reference Example The white hydrolyzate obtained in 1 was heated under the same conditions as in Reference Example 1 except that the heating time was 20 minutes or 3 hours to obtain a yellow product. The diffuse reflection spectra of these products were measured in the same manner as in Reference Example 1. A sample with a heating time of 20 minutes has a reflectance of 69% at 450 nm when the reflectance at 600 nm is 100%, and a sample with a heating time of 3 hours has a reflectance at 450 nm when the reflectance at 600 nm is 100%. The reflectance was 68%. A sample with a heating time of 20 minutes has a reflectance of 68% at 450 nm when the reflectance at 700 nm is 100%, and a sample with a heating time of 3 hours has a reflectance at 450 nm when the reflectance at 700 nm is 100%. The reflectance was 68%.

Reference Example 3 A white hydrolyzate was obtained under the same conditions as in Reference Example 1 except that titanium tetrachloride was replaced with titanium trichloride, and this white hydrolyzate was heated at 400 ° C. for 1 hour to obtain a yellow product. It was. The ESR spectrum (measurement temperature 77K) of this product measured in a state of being irradiated with light through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp) is shown in the middle of FIG. The main signal and two sub-signals having the same g value as shown in are shown.

Reference Example 4 1.6 kg of anatase-type titanium dioxide powder (C-02 manufactured by Ishihara Sangyo Co., Ltd.) was filled in a heating container having an inner wall having an inner wall of 25 liters and mounted on an external heat type rotary kiln device. The inside of the heating container was purged with nitrogen gas, and then ammonia gas was circulated at 1.5 liters / minute in terms of nitrogen gas. At the same time, the temperature inside the container was set to 400 ° C. by an external heater, and the container was heated for 90 minutes while rotating. After heating, it was cooled to room temperature to give a yellow product. FIG. 5 shows an ESR spectrum (measurement temperature 77K) measured in a state of being irradiated with light through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp).

Reference Example 5 Reference Example 3 g of the powder obtained in 1 was suspended in 100 ml of pure water and stirred for 1 hour using a magnetic stirrer. The obtained solution was suction filtered. The sample remaining on the filter paper was stirred again with pure water and suction filtration was performed. The filtration was repeated 3 times until the filtrate was 6 to 7 on pH test paper. The obtained powder was left in a dryer set at 110 ° C. for a whole day and night and dried to obtain the material of the present invention.

Reference Example 6 Titanium tetrachloride (23 kg) was gradually added to 207 kg of water at a temperature of 0 ° C. filled in a 300 liter reaction vessel (which can be cooled and stirred). At this time, the temperature of the aqueous solution was 6 ° C. at the maximum. Titanium chloride was stirred for 2 days to prepare a transparent titanium tetrachloride aqueous solution. When 12.5% ammonia water was added dropwise while stirring the prepared titanium tetrachloride aqueous solution, the solution gradually became cloudy, and the amount of ammonia water was adjusted so that the cloudy solution had a pH of 8. The cloudy solution was suction filtered. The white precipitate remaining on the filter paper weighed 131 kg. The white precipitate is 200 kg of aqueous ammonia (NH).₃After dispersing in 6%), the mixture was stirred for 24 hours and suction-filtered. The white precipitate after filtration weighed 108 kg. The white precipitate was placed in a forced ventilation shelf type dryer set at 50 ° C. and dried for 4 days. After drying, the sample weighed 17 kg. 1 kg of the dried sample was placed in an alumina crucible (20 × 20 × 5 cm), placed in a gas furnace, a thermocouple was placed on the surface of the sample, and the sample was baked for 1 hour so that the temperature of the sample became 400 ° C. After cooling, a dark yellow material of the invention was obtained. This material was crushed in a mortar and used for the evaluation described below.

Reference Example 7 Reference Example 3 g of the powder prepared in No. 6 was suspended in 100 ml of pure water and stirred for 1 hour using a magnetic stirrer. The obtained solution was suction filtered. The sample remaining on the filter paper was stirred again with pure water and suction filtration was performed. The filtration was repeated 3 times with a pH test paper until the filtrate became 6 to 7. The obtained powder was left in a dryer set at 110 ° C. for 24 hours and dried to obtain the material of the present invention. ..

The ESR of the obtained material of the present invention was measured. However, JEOLJES-TE300 is used for ESR measurement, and under the measurement conditions, the temperature is 77K, the atmosphere is nitrogen (760Torr), the center field is 330mT ± 25mT, the modulation frequency is 100kHz, and the RF power is 1.0mW. The scanning time is 4 minutes, the time is constantly 0.1 seconds, the light source is a 150 W Xe lamp, and a SUPERBRIGHT-152S manufactured by Sanaga Denki Seisakusho Co., Ltd. is used so that the sample can be irradiated with light through the filter GG455 (made in Shott Japan). Was measured. The results are shown in FIG.

Test example Reference example of NOx removal activity Samples prepared in 1, 3, 5, 6 and 7 and commercially available titanium oxide powder (ST-01, manufactured by Ishihara Sangyo Co., Ltd.) (Comparative Example 1) were placed on 0.2 g glass plates (6 x 6 cm) each. Each coated product was placed in a Pyrex glass reaction vessel (inner diameter 160 mm, thickness 25 mm). The light source was irradiated with light as a single light color having a half width of 20 nm by an irradiation device (trade name: SM-5 type CT-10 manufactured by JASCO Corporation) using a 300 W xenon lamp. Simulated contaminated air (NO: 1 ppm) with a humidity of O% RH was continuously supplied to this reaction vessel at a flow rate of 1.5 liters / minute, and NO and NO at the reaction outlet.₂The change in concentration was monitored. The concentration of NO was measured by a chemiluminescent method using ozone. NOx removal rate (%) (= NO reduction rate-NO) at each measurement wavelength from the cumulative value of the monitor value for 1 hour₂Generation rate) was calculated. A Nitrogen Oxides analyzer Model 8840 manufactured by Monitor labs Inc. was used for measuring the NO concentration.

【００４８】

[Table 1] <img file="000002.tif" id="000002" he="035" wi="044" img-format="tif" img-content="drawing" />

Reference Example 8 (Relationship between heating temperature and NOx removal rate) Reference Example Reference example of the white precipitate (hydrolyzed product) obtained in No. 6 except that the heating temperatures were set to 300 ° C, 325 ° C, 350 ° C, 375 ° C, 400 ° C, 425 ° C, 450 ° C, 475 ° C or 500 ° C. The mixture was heated under the same conditions as in 1 (heating time was 1 hour), and further washed and dried under the same conditions as in Reference Example 7 to obtain a yellow product. The diffuse reflectance spectra of these products are measured, and Table 2 shows the reflectance at 450 nm when the reflectance at 600 nm or 700 nm is 100%. For reference, the reflectance of ST-01 manufactured by Ishihara Sangyo Co., Ltd. is also shown in Table 2. Further, the NOx removing activity of each of the obtained samples was measured in the same manner as in the above test example, and is shown in FIGS. 6 to 8.

【００５０】

[Table 2] <img file="000003.tif" id="000003" he="040" wi="110" img-format="tif" img-content="drawing" />

Reference Example 9 (Relationship between heating time and NO removal rate) Reference Example The white precipitate (hydrolyzed product) obtained in No. 6 had the same conditions as in Reference Example 1 (heating temperature was 400) except that the heating time was 0.5 hours, 1 hour, 3 hours, 6 hours or 10 hours. The mixture was heated at (° C.), washed and dried under the same conditions as in Reference Example 7 to obtain a yellow product. The diffuse reflectance spectra of these products are measured, and Table 3 shows the reflectance at 450 nm when the reflectance at 600 nm or 700 nm is 100%. For reference, the reflectance of ST-01 manufactured by Ishihara Sangyo Co., Ltd. is also shown in Table 3. Further, the NOx removing activity of each of the obtained samples was measured in the same manner as in the above test example, and is shown in FIGS. 9 to 11.

【００５２】

[Table 3] <img file="000004.tif" id="000004" he="040" wi="109" img-format="tif" img-content="drawing" />

Reference Example 10-1 (Relationship between cleaning after heating and removal rate (1)) Reference Example 3 g of the powder prepared in No. 6 was suspended in 100 ml of pure water and stirred for 1 hour using a magnetic stirrer. The obtained solution was suction filtered. The sample remaining on the filter paper was stirred again with pure water and suction filtration was performed. The number of times of this filtration was repeated once, twice, three times, five times, or seven times, and the obtained powder was left in a dryer set at 110 ° C. for a whole day and night to be dried, and further obtained. The NOx removing activity of each of the obtained samples was measured in the same manner as in the above test example, and is shown in FIGS. 12 to 14. Further, FIG. 15 shows the relationship between the number of washings and the pH and chloride ion concentration of water separated from the material after washing.

Reference Example 10-2 (Relationship between cleaning after heating and removal rate (2)) Reference example 3 g of the powder prepared in No. 6 was suspended in 100 ml of pure water and left for 10 minutes while applying ultrasonic waves. The obtained solution was suction filtered. The sample remaining on the filter paper was stirred again with pure water and suction filtration was performed. The number of times of this filtration was repeated 0 times, 1 time, or 6 times, and the obtained powder was left in a dryer set at 110 ° C. for 24 hours to dry, and further, NOx of each obtained sample was obtained. The removing activity was measured in the same manner as in the above test example, and is shown in FIG. Further, the IR of each obtained sample was measured, and the IR spectrum with 0 washing times divided by the IR spectrum with 6 washing times (A) and the IR spectrum with 1 washing number were divided with the IR with 6 washing times. FIG. 17 shows (B) divided by the spectrum.

Reference Example 11 (Examination of washing conditions after hydrolysis and before heating) The material of the present invention was obtained in the same manner as in Reference Example 5 except that the stirring time with pure water was 10 minutes or 1 day. The NOx removing activity of each of the obtained samples was measured in the same manner as in the above test example, and the results are shown in Table 4 below.

【００５６】

[Table 4] <img file="000005.tif" id="000005" he="065" wi="109" img-format="tif" img-content="drawing" />

Example 12 (Method for producing visible light responsive material from titanium sulfate (1)) Manufacturing example 1 As a titanium (IV) sulfate solution, an aqueous solution of titanium (IV) sulfate (trade name: Titanium Sulfate (IV) (first-class deer, aqueous solution containing 24% by weight or more of titanium (IV) sulfate) manufactured by Kanto Chemical Co., Ltd.) The undiluted solution was used as it was. While mixing 50 g of this aqueous solution with a stirrer and continuing stirring while adding 58 ml of ammonia water (ammonia stock solution: water = 1: 1) as quickly as possible with a burette, cloudiness began and the degree of solidification gradually increased. Further, ammonia water was added, and the pH was adjusted to 7 with a universal test paper. After 24 hours, it was filtered with a suction filter. The white matter on the filter paper was stirred in ammonia water having a pH adjusted to 11 and filtered again 8 times to wash the filter paper to obtain a white powder. The obtained powder was dried at 50 ° C. to obtain a sample powder G. The BET surface area of the obtained hydrolyzate (sample powder G) is 308.7 m.²It was / g.

Example 12-1 8 g of the sample powder G obtained in Production Example 1 was placed in a crucible, transferred to an electric furnace, fired at 400 ° C. for 60 minutes, and had a BET surface area of 89.4 m.²6.3 g of / g bright yellow powder A was obtained.

Example 12-2 8 g of the sample powder G obtained in Production Example 1 was placed in a crucible, transferred to an electric furnace, fired at a temperature of 300 ° C. for 60 minutes, and had a BET surface area of 101 m.²6.5 g of / g bright yellow powder B was obtained.

Example 12-3 8 g of the sample powder G obtained in Production Example 1 was placed in a crucible, transferred to an electric furnace, fired at a temperature of 500 ° C. for 60 minutes, and had a BET surface area of 52.6 m.²6.2 g of / g pale yellow powder C was obtained.

Comparative Example 12-1 8 g of the sample powder G obtained in Production Example 1 was placed in a crucible, transferred to an electric furnace, fired at a temperature of 100 ° C. for 60 minutes, and had a BET surface area of 249 m.²7.6 g of / g white powder D was obtained.

Comparative Example 12-2 8 g of the sample powder G obtained in Production Example 1 was placed in a crucible, transferred to an electric furnace, fired at a temperature of 200 ° C. for 60 minutes, and had a BET surface area of 200 m.²7.1 g of / g white powder E was obtained.

Comparative Example 12-3 A commercially available titanium oxide powder (ST-01 manufactured by Ishihara Sangyo Co., Ltd.) was designated as powder F. This powder F has a BET surface area of 320 m.²/ G white powder.

Characteristic evaluation The characteristics of the powders obtained in Production Examples 1, 12-1 to 3 and Comparative Examples 12 to 1 to 3 are described by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and NO oxidation activity. It was evaluated by measurement and measurement of the oxidation activity of isopropanol.

1. X-ray diffraction (XRD) The firing temperatures of the sample powder G obtained in Production Example 1, the powders A, B and C obtained in Examples 12-1 to 3, and the powders D, E and F obtained in Comparative Examples 12-13. FIG. 18 shows the result of measuring the change due to the above with an X-ray diffraction analyzer (trade name: RINT-2000 manufactured by Rigaku Denki Co., Ltd.). As shown in FIG. 18, no diffraction pattern was confirmed in powders B, D, E, and G, and a diffraction pattern of anatase crystals was confirmed in powders A, C, and F. It can be seen that anatase-type titanium oxide is produced and grows by firing to increase the strength.

2. X-ray photoelectron spectroscopy (XPS) The ratio of titanium and oxygen of the sample powder G obtained in Production Example 1, the powder A obtained in Example 12-1, and the powder F of Comparative Example 12-3 is determined by an X-ray photoelectron spectroscopy (ESCA) apparatus. (Product name: Quantum 2000 manufactured by ULVAC-PHI Co., Ltd.). X-ray photoelectron spectroscopy was performed under the following conditions. Excited X-ray generation conditions: An electron beam with a pem diameter of 100 μm-110 W was incident on the Al target, and the monochromatic X-ray (AlKα1) generated from the electron beam was used as the excitation source. Analysis area, mode: Analysis area; 1500 μm × 100 μmφ, beam diameter used; 100 μmφ Extraction angle: 90 degrees Path energy: 187.85eV (Survey), 23.50eV (Multiplex) Step width: 1.6eV (Survey), 0.1eV (Multiplex)

The abundance ratio of oxygen element and titanium element calculated from the area of the peak attributed to the 2p electron of titanium obtained by X-ray photoelectron spectroscopy and the area of the peak attributed to the 1s electron of oxygen (O). / Ti) was 2.45 for sample powder G, 2.28 for powder A, and 2.40 for commercially available powder F, respectively. In theory, the abundance ratio (O / Ti) of oxygen element and titanium element in normal (commercially available) titanium oxide powder (IV) should be 2.00, but in this measurement, it is a commercially available product. Given that the measured value of a certain powder F was 2.40, the abundance ratio (O / Ti) of the theoretical (actual) oxygen element and the titanium element of the powder A, which was a smaller measured value. Is found to be at least less than 2.00.

3. Measurement of NOx removal activity NOx removal of sample powder G obtained in Production Example 1, powders A, B and C obtained in Examples 12-1 to 3 and powders D, E and F obtained in Comparative Examples 12-1 to 13. The activity was measured according to the method described in the above test example. The results are shown in Table 5.

【００６９】

[Table 5] <img file="000006.tif" id="000006" he="075" wi="109" img-format="tif" img-content="drawing" />

4. Measurement of isopropanol oxidative activity Sample powder G obtained in Production Example 1, powders A, B and C obtained in Examples 12-1 to 3 and powders D, E and F obtained in Comparative Examples 12-1 to 3 are 0, respectively. A glass plate (6 × 6 cm) coated with 2 g was placed in a glass bell jar type reactor (volume: 1.9 liters). A 300W halogen lamp is used as the light source, and a cut filter (Toshiba Corporation product name: IRA-25S, cuts light with a wavelength of 650 nm or more) and a cut filter (Toshiba Corporation product name: L-42, (Cut light with a wavelength less than 420 nm) was used. After sufficiently exhausting the inside of the system, 2-propanol was injected into the reaction vessel to obtain a reaction gas having a concentration of 500 ppm. After 2-propanol reached adsorption equilibrium, light irradiation was performed for 2 hours. The reaction gas was analyzed by gas chromatography (FID), and the amount of increase in the concentration of acetone produced by oxidation (acetone production rate (ppm / min)) was measured. The results are shown in Table 6.

【００７１】

[Table 6] <img file="000007.tif" id="000007" he="075" wi="077" img-format="tif" img-content="drawing" />

From Table 6, the powder A obtained in Example 12-1 has a high acetone production rate (ppm / min) and high acetone production characteristics (photocatalytic function) in the oxidation of 2-propanol by visible light irradiation. It can be seen that it has. On the other hand, the powders G, E and F have almost no increase in acetone, indicating that they do not have a photocatalytic function.

4. Measurement with color analyzer Sample powder G obtained in Production Example 1, titanium oxide powders A, B and C obtained in Examples 12 to 1 to 3, and titanium oxide powders D and E obtained in Comparative Examples 12 to 1 to 3 and In order to see the degree of light absorption of F, the reflectance of each powder when irradiated with light of a wavelength in the visible light range by a color analyzer (Tokyo Denshoku Technology Center, trade name: TC-1800) Was measured. The result is shown in FIG. From FIG. 19, it can be seen that the powders A, C and B absorb more visible light, so that they are colored and have visible light activity (photocatalytic function). Table 7 shows the reflectance of each powder (the reflectance when irradiating light having a wavelength of 450 nm, where 1 is the reflectance when irradiating light having a wavelength of 600 nm).

【００７４】

[Table 7] <img file="000008.tif" id="000008" he="070" wi="092" img-format="tif" img-content="drawing" />

The ESR spectrum of the powder A obtained in Example 12-1 was measured. The measurement was performed in vacuum (0.1 Torr) at 77 K. The measurement conditions are the same as in Reference Example 1. FIG. 20 (measurement temperature 77K) shows an ESR spectrum measured in a state of being irradiated with light through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp). The ESR spectrum in the dark was also measured, but no signal was substantially observed.

In the spectrum shown in FIG. 20, a main signal having a g value of 2.004 to 2.007 and two sub signals having a g value of 1.985 to 1.986 and 2.024 were observed. .. When the white hydrolyzate is dried at 50 ° C., the main signal having a g value of 2.004 to 2.007 and the g values of 1.985 to 1.986 and 2.024 are obtained. No two sub-signals were observed under any of the ESR measurement conditions.

Example 13 (Method for producing visible light responsive material from titanium sulfate (2)) Add 50 g of a 24% titanium sulfate solution (Kanto Chemical Co., Inc., first-class deer) to 400 mL of distilled water, and stir with a magnetic stirrer. Concentrated ammonia water (28%, Kanto Chemical Co., Inc., special grade) is added thereto to perform a neutralization reaction. After the neutralization reaction, adjust to pH 7 and stir for 15 minutes. At this time, the stirrer may not rotate, so add distilled water (200 mL). After 15 minutes, stop stirring, leave for a while, and discard the supernatant. Filtration is performed in Nutche, at which time washed with 2 L of ammonia water (5:95). This work is a method of adding ammonia water when the cake is formed on the filter paper. After that, the obtained product was dried at 60 ° C. for 24 hours and calcined at 400 ° C. for 1 hour to obtain the visible light responsive material of the present invention. The NOx removing activity of the obtained material was measured in the same manner as in the above test example, and is shown in Table 8.

【００７８】

[Table 8] <img file="000009.tif" id="000009" he="030" wi="109" img-format="tif" img-content="drawing" />

The ESR spectrum of the obtained material was measured. The measurement was performed in vacuum (0.1 Torr) at 77 K. The measurement conditions are the same as in Reference Example 1. FIG. 21 shows an ESR spectrum measured in a state where light is irradiated to FIG. 21 (measurement temperature 77K) through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp).

In the spectrum shown in FIG. 21, a main signal having a g value of 2.004 to 2.007 and two sub signals having a g value of 1.985 to 1.986 and 2.024 were observed. .. When the white hydrolyzate is dried at 50 ° C., the main signal having a g value of 2.004 to 2.007 and the g values of 1.985 to 1.986 and 2.024 are obtained. No two sub-signals were observed under any of the ESR measurement conditions.

Reference Example 14 (Manufacturing method from alkoxide) 30 g of titanium isopropoxide was gradually added to 200 g of pure water with stirring (water to titanium isopropoxide molar ratio = about 10: 1). After stirring the obtained solution for about 30 minutes, the precipitate (hydrolyzate) was collected by filtration, and the precipitate (hydrolyzate) was suspended in pure water and stirred for 1 day, and then filtered. It was dried at ° C and calcined at 400 ° C for 1 hour. The obtained white powder is used as sample A. Instead of suspending the precipitate (hydrolyzate) in pure water and stirring for 1 day, the precipitate (hydrolyzate) was suspended in aqueous ammonia (ammonia concentration: 6%) and stirred for 1 day. Uses the yellow powder as sample B in the same manner as in the above operation. The NOx removing activity of Samples A and B was measured in the same manner as in the above test method. The results are shown in Table 6 below.

【００８２】

[Table 9] <img file="000010.tif" id="000010" he="060" wi="108" img-format="tif" img-content="drawing" />

From the results shown in Table 9, it can be seen that a material made of titanium oxide having visible light responsiveness can be obtained by heat-treating titanium oxide (titanium hydrolyzate) in the presence of ammonia.

The ESR spectrum of the obtained material was measured. The measurement was performed in vacuum (0.1 Torr) at 77 K. The measurement conditions are the same as in Reference Example 1. FIG. 22 shows an ESR spectrum measured in a state where light is irradiated to FIG. 22 (measurement temperature 77K) through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp).

In the spectrum shown in FIG. 22, a main signal having a g value of 2.004 to 2.007 and two sub signals having a g value of 1.985 to 1.986 and 2.024 were observed. .. When the white hydrolyzate is dried at 50 ° C., the main signal having a g value of 2.004 to 2.007 and the g values of 1.985 to 1.986 and 2.024 are obtained. No two sub-signals were observed under any of the ESR measurement conditions.

Example 15 (Production method from titanium sulfate hydrolyzate) The hydrolyzate obtained by substituting the aqueous sodium hydroxide solution for the aqueous ammonia in Example 12 was suspended in pure water, stirred for 1 day, filtered, dried at 110 ° C., and further calcined at 400 ° C. for 1 hour. did. The obtained white powder is used as sample C. Instead of suspending the precipitate (hydrolyzate) in pure water and stirring for 1 day, the precipitate (hydrolyzate) was suspended in aqueous ammonia (ammonia concentration: 6%) and stirred for 1 day. Except for the above, the yellow powder is used as sample D in the same manner as in the above operation. When the NOx removing activity of Samples C and D was measured in the same manner as in the above test method, as in the case of Samples A and B in Example 14, Sample C baked at 400 ° C. for 1 hour in the absence of ammonia was found. Sample D, which was fired at 400 ° C. for 1 hour in the presence of ammonia, had visible light responsiveness, whereas it did not have visible light responsiveness.

Reference Example Reference Example 7. The molar ratio of oxygen to titanium in titanium oxide in the visible light responsive material of the present invention obtained in Examples 12-1 and 13 was measured using X-ray photoelectron spectroscopy (ESCA). As a control sample, Wako Pure Chemical Industries' reagent primary titanium dioxide was used. The measurement by X-ray photoelectron spectroscopy (ESCA) was performed in the same manner as the X-ray photoelectron spectroscopy shown in the characterization of Example 12. The results are shown in Table 10.

【００８８】

[Table 10] <img file="000011.tif" id="000011" he="045" wi="104" img-format="tif" img-content="drawing" />

【００８９】

According to the present invention, it is possible to provide a novel photoresponsive material that also responds to visible light, and this material can be manufactured at a lower cost by using a wet method. In the present invention, titanium oxide having visible light responsiveness as a photocatalyst can be produced easily and inexpensively by using existing equipment used in a wet method such as a so-called sulfuric acid method.

[Simple explanation of drawings]

FIG. 1 is an ESR spectrum measured at 77K in a vacuum of a visible light responsive material (Reference Example 1). The upper row is the spectrum under darkness, the middle row is the spectrum under irradiation of light having a wavelength of 420 nm or more (the light of less than 420 nm is cut off from the light of the mercury lamp), and the lower row is the spectrum of less than 420 nm. It is a spectrum when light is irradiated without cutting off the light of a mercury lamp without cutting off the light.

FIG. 2 is an ESR spectrum of a visible light responsive material (Reference Example 1) measured at room temperature in a vacuum. The upper row is the spectrum under darkness, the middle row is the spectrum under irradiation of light having a wavelength of 420 nm or more (the light of less than 420 nm is cut off from the light of the mercury lamp), and the lower row is the spectrum of less than 420 nm. It is a spectrum when light is irradiated without cutting off the light of a mercury lamp without cutting off the light.

FIG. 3 is an XRD measurement result of a product (upper row) and a hydrolyzate (dried at 50 ° C.) (lower row) of Reference Example 1.

FIG. 4 shows a measurement atmosphere in vacuum (upper stage), air (middle stage), or isopropanol (lower stage) through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp). ESR spectrum measured under light irradiation conditions.

FIG. 5 is an ESR spectrum of the product obtained in Reference Example 4 measured in a state of being irradiated with light through a filter (L-42) that cuts light of less than 420 nm (using a 500 W high-pressure mercury lamp). The measurement temperature 77K) is shown.

FIG. 6 is a diagram showing the relationship between the NO removal rate and the heating temperature shown in Reference Example 8.

FIG. 7 shows NO shown in Reference Example 8.₂It is a figure which obtained the relationship between the production rate of, and the heating temperature.

FIG. 8 is a diagram showing the relationship between the NOx removal rate and the heating temperature shown in Reference Example 8.

FIG. 9 is a diagram showing the relationship between the NO removal rate and the heating time shown in Reference Example 9.

FIG. 10 shows NO shown in Reference Example 9.₂It is a figure which found the relationship between the production rate of, and the heating time.

FIG. 11 is a diagram showing the relationship between the NOx removal rate and the heating time shown in Reference Example 9.

FIG. 12 is a diagram showing the relationship between the number of washings after heating and the NO removal rate shown in Reference Example 10-1.

FIG. 13 shows the number of washings after heating and NO shown in Reference Example 10-1.₂It is a figure which found the relationship with the generation rate of.

FIG. 14 is a diagram showing the relationship between the number of washings after heating and the NOx removal rate shown in Reference Example 10-1.

FIG. 15 shows the relationship between the number of washings and the pH and chlorine ion concentration of water separated from the material after washing (titanium chloride was used as a raw material for the hydrolyzate) shown in Reference Example 10-1.

FIG. 16 shows the NOx removing activity of each sample obtained in Reference Example 10-2.

FIG. 17 shows an IR spectrum obtained in Reference Example 10-2 with 0 washes divided by an IR spectrum with 6 washes (A) and an IR spectrum with 1 washes divided by an IR spectrum with 6 washes. The one divided by the spectrum (B) is shown.

FIG. 18 is firing of sample powder G obtained in Production Example 1, powders A, B and C obtained in Examples 12-1 to 3, and D and E obtained in Comparative Examples 12-1 to 2. It is explanatory drawing which shows the result of having measured the change with temperature (F of Comparative Example 12-3 is a commercial product) by the X-ray diffraction analyzer.

FIG. 19 shows sample powder G obtained in Production Example 1, powders A, B and C obtained in Examples 12-13, and D, E and F obtained in Comparative Examples 12-13. It is a figure which shows the reflectance spectrum measured by the color analyzer.

FIG. 20 shows light having a wavelength of 77 K and 420 nm or more (cut off light of less than 420 nm among the light of a high-pressure mercury lamp) in a vacuum of the visible light responsive material (Example 12-1) of the present invention. ESR spectrum measured under irradiation.

FIG. 21: In a vacuum of the visible light responsive material (Example 13) of the present invention, under irradiation with light having a wavelength of 77 K and 420 nm or more (cut off light of less than 420 nm among the light of a high-pressure mercury lamp). ESR spectrum measured in.

FIG. 22 is measured in a vacuum of a visible light responsive material (Reference Example 14) under irradiation with light having a wavelength of 77 K and 420 nm or more (cut off light of less than 420 nm among the light of a high-pressure mercury lamp). ESR spectrum.

FIG. 23 shows an ESR spectrum (upper, Dark) measured in darkness at 77K in nitrogen (760Torr) of a visible light responsive material (Reference Example 7), and nitrogen (Reference Example 7) of a visible light responsive material (Reference Example 7). ESR spectrum (middle stage,&gt; 455 nm) measured under irradiation of light having a wavelength of 77 K, 455 nm or more (cut off light of less than 455 nm among the light of the Xe lamp) in 760 Torr) and measurement under light irradiation. The spectrum obtained by subtracting the ESR spectrum measured in the dark from the obtained ESR spectrum (lower row,&gt; 455 nm-Dark) is shown.

Continuation of front page (51) Int.Cl.⁷ Identification code FI C02F 1/30 C02F 1/72 101 1/72 101 B01D 53/36 J (31) Priority claim number Japanese Patent Application 2000-399193 (P2000-399193) (32) Priority date December 27, 2000 (December 27, 2000) (33) Priority claiming country Japan (JP) Application for accelerated examination (56) References Japanese Patent Application Laid-Open No. 2001-72419 (JP, A) PHOTOCATALYTIC AC TIVITY OF NOx-DOPE D TiO2 IN THE VISI BLE LIGHT REGION, C medical Physics Le tters, January 1986, Volume e 123, number 1, 2, p126 128 (58) Surveyed field (Int.Cl.⁷, DB name) C01G 23/053 B01J 35/02