Visible light responsive material and method for producing the same

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

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.

【0002】

[Conventional technology]

It is known that antibacterial tiles, self-cleaning building materials, super-hydrophilic materials, deodorant / deodorant materials, water purification, cancer treatment, etc. can be performed using photocatalysts made of anatase-type titanium dioxide (optical clean revolution (optical clean revolution (optical 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. Antibacterial paints are disclosed in JP-A-8-67835 and JP-A-8-164334. Further, WO 96/29375 discloses a super-hydrophilic material.

【0003】

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.

【0004】

Therefore, the development of photocatalysts 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 around 500 ° C. in an oxidizing atmosphere. However, this method uses titanium alkoxide and a chelating agent (for example, acetylacetone), 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.

【0005】

In addition, 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 virtually no activity above 470 nm. On the other hand, the photocatalyst described in WO00 / 10706 can photooxidize NO not only in the vicinity of 420 nm but also in light having a wavelength of around 600 nm, and can be said to be a truly visible photocatalyst.

【0006】

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.

【0007】

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.

【0008】

[Means for solving problems]

The present invention is a titanium oxide containing at least anatase-type titanium oxide, and the main signal and g having a g value of 2.004 to 2.007 in ESR measured under vacuum and under irradiation with light having a wavelength of 420 nm or more at 77 K. Two sub-signals with values of 1.985 to 1.986 and 2.024 are observed, and these three signals are characterized by being microscopically observed or substantially non-observed in vacuum, 77K, in the dark. Regarding visible light responsive materials.

【0009】

Furthermore, 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, at a wavelength of 450 nm of the produced material. The present invention relates to a method for producing a visible light responsive material, which comprises ending the heating when the absorption of light is larger than the absorption of light at a wavelength of 450 nm of the raw material titanium compound.

【0010】

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 2.004 to 2.004 in ESR measured under irradiation with light having a wavelength of 420 nm or more at 77 K in a vacuum. A main signal with a g value of 2.007 (the signal with the strongest intensity) and two sub-signals with g values of 1.985 to 1.986 and 2.024 (a signal with a lower intensity than the main signal) are observed. 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. This is the 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 passing through, the main signal (the strongest signal) with a g value of 2.004 to 2.007 and the two sub signals with g values of 1.985 to 1.986 and 2.024. A signal (a signal with a lower intensity than the main signal) may be observed.

【0011】

The visible photocatalyst made of titanium dioxide with stable oxygen defects 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 a signal having a g value of 2.003 to 2.004 in ESR measured in vacuum at 77K and in the dark. It is different from the spectrum exhibited by visible light responsive materials.

【0012】

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 can have, for example, a molar ratio of oxygen to titanium less than 2.00, for example 1.00 to 1.99, or 1.50 to 1.99. 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.

【0013】

Figure 1 shows a typical spectrum of ESR measured at 77K in vacuum for the visible light responsive material of the present invention. In the figure, the upper part is the spectrum under darkness, and the middle part is the spectrum under irradiation of light having a wavelength of 420 nm or more (the light of the mercury lamp, the light 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).

【0014】

In the upper spectrum of FIG. 1, the main signal having a g value of 2.004 to 2.007 is observed minutely, but the two sub-signals having a g value of 1.985 to 1.986 and 2.024 are substantially not observed. Furthermore, when comparing the upper spectrum and the middle spectrum 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 two sub signals having a g value of 1.985 to 1.986 and 2.024 are apparent. Is considerably more intense than in the upper spectrum. Moreover, as is clear from comparing the spectra in the middle and lower rows of FIG. 1, the intensities of the main signal having a g value of 2.004 to 2.007 and the intensities of the two sub signals having a g value of 1.985 to 1.986 and 2.024 are both. There is virtually no difference whether or not the irradiation light contains light of less than 420 nm.

【0015】

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 in vacuum, at room temperature, and in the dark is observed minutely, but the g value is high. The two sub-signals 1.985 to 1.986 and 2.024 are virtually non-observable. Furthermore, in vacuum and at room temperature, the above three signals are measured in ESR under light irradiation with a wavelength of 420 nm or more and under light irradiation of a mercury lamp that does not cut off light below 420 nm. 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).

【0016】

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.

【0017】

The visible light responsive material of the present invention further has a sub-signal having 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. You can also do it. Sub-signals with g values of 2.009 to 2.010 are shown in the ESR spectrum in the middle of FIG.

【0018】

As described above, the visible light responsive material of the present invention is a material having a characteristic ESR signal, but at the same time, it is also a material having coloring, for example, having a reflectance of 1 (reflectance to light having a wavelength of 600 nm). Or 100%), the reflectance for light having a wavelength of 450 nm can be 0.85 (or 85%) or less, preferably 0.80 (or 80%) or less, and more preferably 0.70 (or 70%) or less. 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.

【0019】

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

【0020】

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.

【0021】

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 or intermittently 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 as a target. 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 to 80 ° C, but hydrolysis at room temperature is relatively low in crystallinity or non-crystalline. It may be preferable from the viewpoint of obtaining high quality titanium dioxide.

【0022】

The hydrolyzate of titanium chloride or titanium sulfate with ammonium hydroxide is preferably used as a raw material titanium compound after washing 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 the 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 can be 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 performed 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 performed 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.

【0023】

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 showing 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 and time, etc., the absorption of light at a wavelength of 450 nm may reach up to about 60%. The characteristics of visible light responsive materials 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 (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.

【0025】

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). Figure 6 shows the NO removal rate, Figure 7 shows NO₂Figure 8 shows the NOx removal rate. (Details are shown in Example 8.) From these figures, the NOx removal rate by light with wavelengths of 420 nm and 470 nm is relatively high when heated in the range of 300 to 450 ° C, at 325 to 425 ° C. It was found to be higher with heating in the range, and the NOx removal rate by light with wavelengths of 520 nm and 570 nm was relatively high with heating in the range of 325 to 450 ° C, and in the range of 350 to 425 ° C. It turns out that it is higher with heating. 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.

【0026】

Figures 9 to 11 show the relationship between the NOx removal (oxidation) activity and the heating time (heating temperature was 400 ° C). Figure 9 shows the NO removal rate, Figure 10 shows NO₂The 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. Moreover, since the NOx removal rate does not fluctuate 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.

【0027】

For the above heating, a rotary kiln, a tunnel kiln, a muffle furnace or the like commonly 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.

【0028】

In addition, 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 titanium compound before heating) is obtained by, for example, hydrolyzing titanium chloride with ammonium hydroxide, a considerable amount of the hydrolyzate is used. 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 the 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. Figure 12 shows the NO removal rate, Figure 13 shows NO₂Figure 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.

【0029】

Further, in this case, the material obtained by heating is washed with water or an aqueous solution so that the pH of the water or aqueous solution separated from the material after washing is, for example, 3.5 or more (pH 3.5 to 7). Or, the amount of chlorine ion (when titanium chloride is used as the raw material of the hydrolyzate) or the amount of sulfate ion (when titanium sulfate is used as the raw material of the hydrolyzate) contained in the water or aqueous solution separated from the material after washing. It is preferable to reduce the amount of water. 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. In addition, although the cleaning conditions are slightly different, the result of investigating 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.

【0030】

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.

【0031】

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

【0032】

By using the visible light responsive material of the present invention, sterilization, algae-proofing, fungicide-proofing, and / or antifouling methods can be provided. 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.

【0033】

[Example]

Examples of the present invention are shown below, but the present invention is not limited thereto. 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 solution of titanium tetrachloride. While stirring 200 g of this aqueous solution with a stirrer, about 50 ml of aqueous ammonia (containing 13 wt% as NH3) was added as soon as possible. The amount of ammonia water 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 for 15 minutes, filtration was performed with 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 electric furnace at 400 ° C. for 1 hour to obtain a yellow product.

【0034】

The XRD measurement results of the obtained product are shown in the upper part of Fig. 3. At the same time, the XRD measurement results of the white hydrolyzate dried at 50 ° C are also shown in the lower part of Fig. 3. 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, the reflectance at 450 nm was 61% when the reflectance at 600 nm of the obtained product was 100%, whereas the white hydrolyzate was dried at 50 ° C. When the reflectance at 600 nm was 100%, the reflectance at 450 nm was 95%. In addition, the reflectance at 450 nm was 61% when the reflectance at 700 nm of the obtained product was 100%, whereas the reflectance of the white hydrolyzate at 50 ° C was 700 nm. The reflectance at 450 nm was 95% when the reflectance was 100%.

【0035】

In addition, the ESR spectrum of the obtained product was measured. The measurement was performed in vacuum (0.1 Torr or less) at 77 K or at room temperature using an ESR device, ES-RE2X, and JEOL Ltd. The measurement conditions are as follows. [Basic parameters] Measurement temperature 77K or normal 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)) g = g_mn× H_mn/ (H_mn+ H) H_mn: Mn²⁺Marker magnetic field, H: H_mnAmount of change in magnetic field from [0036]

In Fig. 1 (measurement temperature 77K) and Fig. 2 (measurement temperature normal temperature), the upper row shows the ESR spectrum in the dark, and the middle row shows the filter (L-42) that cuts light less than 420 nm (using a 500W high-pressure mercury lamp). ESR spectrum measured with light irradiated through, ESR measured with light irradiation 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 spectra are shown respectively.

【0037】

Comparing the upper and middle spectra of Fig. 1, it is clear that in the middle spectrum, the main signal with g values of 2.004 to 2.007 and the two sub signals with g values of 1.985 to 1.986 and 2.024 are the upper spectra. Was greater in strength. Comparing the spectra in the middle and lower rows of Fig. 1, it is clear that the intensities of the main signal with g values of 2.004 to 2.007 and the intensities of the two sub signals with g values of 1.985 to 1.986 and 2.024 are both irradiated. There was virtually no difference even if the light contained light of less than 420 nm.

【0038】

Further, as shown in FIG. 2, the visible light responsive material of 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. In addition, when the white hydrolyzate is dried at 50 ° C, the main signal having a g value of 2.004 to 2.007 and the two sub signals having a g value of 1.985 to 1.986 and 2.024 are both ESRs. It was not observed even under the measurement conditions.

【0039】

The ESR spectrum is measured in the same manner as above under the condition that the measurement atmosphere that was vacuum is air or isopropanol and the light is irradiated through a filter (L-42) that cuts light below 420 nm (using a 500 W high-pressure mercury lamp). It was measured. The results are shown in Fig. 4. 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.

【0040】

Example 2 The white hydrolyzate obtained in Example 1 was heated under the same conditions as in 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 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%.

【0041】

Example 3 A white hydrolyzate was obtained under the same conditions as in 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. Obtained. The ESR spectrum (measurement temperature 77K) of this product measured under light irradiation through a filter (L-42) that cuts light below 420 nm (using a 500 W high-pressure mercury lamp) is shown in the middle of Fig. 1. The main signal and two sub-signals having the same g value as shown in are shown.

【0042】

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 with an inner wall of 25 liters and attached to 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. Figure 5 shows the ESR spectrum (measurement temperature 77K) measured under light irradiation through a filter (L-42) that cuts light below 420 nm (using a 500 W high-pressure mercury lamp).

【0043】

Example 5 3 g of the powder obtained in Example 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 became 6 to 7 with 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.

【0044】

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, this 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 fired for 1 hour at a temperature of 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.

【0045】

Example 7 3 g of the powder prepared in Example 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 reached 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. It was.

【0046】

The ESR of the obtained material of the present invention was measured. However, JEOL JES-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, the RF power is 1.0mW, and scanning. The time was 4 minutes, the time was constantly 0.1 seconds, the light source was a 150 W Xe lamp, and the sample was measured using SUPERBRIGHT-152S manufactured by Sanaga Denki Seisakusho Co., Ltd. so that the sample could be irradiated with light through the filter GG455 (made in Schott Japan). .. The results are shown in FIG.

【0047】

Test example NOx removal activity Samples prepared in Examples 1, 3, 5, 6 and 7 and commercially available titanium oxide powder (ST-01, manufactured by Ishihara Sangyo Co., Ltd.) (Comparative Example 1) are each 0.2 g glass plate (6 x 6 cm). Each of the coatings was placed in a Pyrex (registered trademark) glass reaction vessel (inner diameter 160 mm, thickness 25 mm). The light source was irradiated with light as a single light color with a half width of 20 nm by an irradiation device using a 300 W xenon lamp (trade name: SM-5 type CT-10 manufactured by Nippon Kogaku Co., Ltd.). 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 the chemiluminescence 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 to measure the NO concentration.

【0048】

[table 1]

<img file="JP2002255555A_D0001.tif" />【0049】

Example 8 (Relationship between heating temperature and NOx removal rate) The white precipitate (hydrolyzate) obtained in Example 6 was heated at 300 ° C, 325 ° C, 350 ° C, 375 ° C, 400 ° C, 425 ° C, 450 ° C, 475 °. The mixture was heated under the same conditions as in Example 1 (heating time was 1 hour) except that the temperature was C or 500 ° C., and further washed and dried under the same conditions as in 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="JP2002255555A_D0002.tif" />【0051】

Example 9 (Relationship between heating time and NO removal rate) The white precipitate (hydrolyzate) obtained in Example 6 had the same conditions as in Example 1 (heating temperature was 400) except that the heating time was 0.5 hour, 1 hour, 3 hours, 6 hours or 10 hours. The mixture was heated at ° C), washed and dried under the same conditions as in 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="JP2002255555A_D0003.tif" />【0053】

Example 10-1 (Relationship between cleaning after heating and removal rate (1)) 3 g of the powder prepared in Example 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 24 hours, dried, and 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. 12 to 14. In addition, 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.

【0054】

Example 10-2 (Relationship between cleaning after heating and removal rate (2)) 3 g of the powder prepared in Example 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 a whole day and night to dry, and further, for each obtained sample. The NOx removing activity was measured in the same manner as in the above test example, and is shown in FIG. Furthermore, the IR of each obtained sample was measured, and the IR spectrum with 0 washes divided by the IR spectrum with 6 washes (A) and the IR spectrum with 1 washes were divided into IRs with 6 washes. FIG. 17 shows (B) divided by the spectrum.

【0055】

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 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="JP2002255555A_D0004.tif" />【0057】

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) (deer grade 1, 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. Ammonia water was further added, and the pH was adjusted to 7 with a universal test strip. 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, and washed 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.

【0058】

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.

【0059】

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 bright yellow powder B of / g was obtained.

【0060】

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.

【0061】

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.

【0062】

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

【0063】

Comparative Example 12-3 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.²It is a white powder of / g.

【0064】

Characterization The characteristics of the powders obtained in Production Examples 1, 12-1 to 3 and Comparative Examples 12-1 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.

【0065】

1. X-ray diffraction (XRD) Sintering temperatures 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 3 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 anatas crystals was confirmed in powders A, C, and F. It can be seen that anatas-type titanium oxide is produced and grows by firing to increase the strength.

【0066】

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. Excitation X-ray generation conditions: An electron beam with a pome diameter of 100 μm-110W 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) [0067]

Absence ratio of oxygen element and titanium element (O / Ti) 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. The sample powder G was 2.45, the powder A was 2.28, and the commercially available powder F was 2.40, respectively. In theory, the abundance ratio (O / Ti) of oxygen element to titanium element in normal (commercially available) titanium oxide powder (IV) should be 2.00, but in this measurement, it is a commercially available powder. Given that the measured value of F was 2.40, the theoretical (actual) oxygen element to titanium element abundance ratio (O / Ti) of powder A, which was a smaller measured value, was at least 2.00. It turns out that it is less than.

【0068】

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 3 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="JP2002255555A_D0005.tif" />【0070】

4. Measurement of isopropanol oxidation 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 0.2, respectively. A glass plate (6 × 6 cm) coated with 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 Co., Ltd. product name: IRA-25S, cuts light with a wavelength of 650 nm or more) and a cut filter (Toshiba Co., Ltd. product name: L-42, (Cut light with wavelengths less than 420 nm) was used. After sufficiently exhausting the inside of the system, 2-propanol was injected into the reaction vessel to prepare 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="JP2002255555A_D0006.tif" />【0072】

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

【0073】

4. Measurement with color analyzer Sample powder G obtained in Production Example 1, titanium oxide powders A, B and C obtained in Examples 12-1 to 3 and titanium oxide powders D and E obtained in Comparative Examples 12-1 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 results are 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 (when the reflectance is 1 when irradiated with light having a wavelength of 600 nm, the reflectance when irradiated with light having a wavelength of 450 nm).

【0074】

[Table 7]

<img file="JP2002255555A_D0007.tif" />【0075】

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

【0076】

In the spectrum shown in FIG. 20, a main signal having a g value of 2.004 to 2.707 and two sub signals having a g value of 1.985 to 1.986 and 2.024 were observed. In addition, when the white hydrolyzate is dried at 50 ° C, the main signal having a g value of 2.004 to 2.007 and the two sub signals having a g value of 1.985 to 1.986 and 2.024 are both ESRs. It was not observed even under the measurement conditions.

【0077】

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 grade 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="JP2002255555A_D0008.tif" />【0079】

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

【0080】

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. In addition, when the white hydrolyzate is dried at 50 ° C, the main signal having a g value of 2.004 to 2.007 and the two sub signals having a g value of 1.985 to 1.986 and 2.024 are both ESRs. It was not observed even under the measurement conditions.

【0081】

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 baked 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. Except for the above, the yellow powder is used 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="JP2002255555A_D0009.tif" />【0083】

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.

【0084】

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

【0085】

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. In addition, when the white hydrolyzate is dried at 50 ° C, the main signal having a g value of 2.004 to 2.007 and the two sub signals having a g value of 1.985 to 1.986 and 2.024 are both ESRs. It was not observed even under the measurement conditions.

【0086】

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 1 at 400 ° C. Baked for hours. 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.

【0087】

Reference example The molar ratio of oxygen to titanium in titanium oxide in the visible light responsive material of the present invention obtained in Examples 7, 12-1 and 13 was measured using X-ray photoelectron spectroscopy (ESCA). As a control sample, Wako Pure Chemical's reagent primary titanium dioxide was used. The X-ray photoelectron spectroscopy (ESCA) measurement 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="JP2002255555A_D0010.tif" />【0089】

[Effect of the invention]

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]

[Figure 1]

ESR spectrum measured at 77K in vacuum of the visible light responsive material of the present invention (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.

[Figure 2]

ESR spectrum measured at room temperature in vacuum of the visible light responsive material (Example 1) of the present invention. 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]

XRD measurement results of the product (upper) and hydrolyzate (dried at 50 ° C) (lower) of Example 1.

[Fig. 4]

Conditions in which the measurement atmosphere is in vacuum (upper stage), air (middle stage), or isopropanol (lower stage), and light is irradiated through a filter (L-42) that cuts light below 420 nm (using a 500 W high-pressure mercury lamp). ESR spectrum measured in.

[Fig. 5]

ESR spectrum (measurement temperature 77K) of the product obtained in Example 4 measured under light irradiation through a filter (L-42) that cuts light below 420 nm (using a 500 W high-pressure mercury lamp). Is shown.

[Fig. 6]

It is a figure which investigated the relationship between the removal rate of NO and the heating temperature shown in Example 8.

[Fig. 7]

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

[Fig. 8]

It is a figure which obtained the relationship between the NOx removal rate and the heating temperature shown in Example 8.

[Fig. 9]

It is a figure which investigated the relationship between the removal rate of NO and the heating time shown in Example 9.

[Fig. 10]

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

[Fig. 11]

It is a figure which investigated the relationship between the NOx removal rate and the heating time shown in Example 9.

[Fig. 12]

It is a figure which investigated the relationship between the number of washings after heating and the removal rate of NO shown in Example 10-1.

[Fig. 13]

Number of washes after heating and NO shown in Example 10-1₂It is a figure which found the relationship with the generation rate of.

[Fig. 14]

FIG. 5 is a diagram showing the relationship between the number of washings after heating and the NOx removal rate shown in Example 10-1.

[Fig. 15]

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 Example 10-1 is shown.

[Fig. 16]

The NOx removing activity of each sample obtained in Example 10-2 is shown.

[Fig. 17]

The IR spectrum obtained in Example 10-2 with 0 washes divided by the IR spectrum with 6 washes (A) and the IR spectrum with 1 wash was divided by the IR spectrum with 6 washes. The thing (B) is shown.

[Fig. 18]

Changes in 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 12 depending on the firing temperature ( It is explanatory drawing which shows the result of having measured the commercial product (F of the comparative example 12-3) by an X-ray diffraction analyzer.

[Fig. 19]

Color analyzers for sample powder G obtained in Production Example 1, powders A, B and C obtained in Examples 12-1 to 3 and D, E and F obtained in Comparative Examples 12-1 to 3 It is a figure which shows the reflectance spectrum measured by.

[Fig. 20]

Measured under vacuum of the visible light responsive material of the present invention (Example 12-1) under irradiation of 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. 21]

The visible light responsive material of the present invention (Example 13) was measured in vacuum under irradiation with light having a wavelength of 420 nm or more (cut off light of less than 420 nm among the light of a high-pressure mercury lamp). ESR spectrum.

[Fig. 22]

The visible light responsive material of the present invention (Example 14) was measured in vacuum under irradiation with light having a wavelength of 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]

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