JP6789566B2 - Manufacturing method of photocatalytic glass - Google Patents

Description

The present invention relates to a photocatalytic glass that exhibits sufficient photocatalytic activity with visible light.

In 1972, anatase-type titanium dioxide electrodes were discovered to have the activity of decomposing water into hydrogen and oxygen with ultraviolet light (Non-Patent Document 1), and the photocatalytic activity of titanium dioxide semiconductors was used to efficiently chemical light energy. A wide range of research has been done with the ultimate goal of converting it into energy.
However, the anatase-type titanium dioxide semiconductor photocatalyst has a relatively large bandgap of 3.2 eV, which corresponds to a wavelength of 388 nm or less. In short, in the case of a photocatalyst using titanium dioxide, ultraviolet light is required for its photocatalytic activity, and only 3 to 4% of the total solar energy reaching the surface of the earth can be used. ..
For this reason, in the last few decades, in order to increase the utilization efficiency of solar energy, photocatalysts having catalytic activity with visible light have been developed, and many photocatalysts containing anatase-type titanium dioxide as a main component have been developed. (For example, Non-Patent Documents 2 to 7). A small number of catalysts that do not contain anatase-type titanium dioxide have also been developed.
For example, Patent Document 1 describes silica glass used in a photocatalytic reaction unit, which efficiently wavelengths light of about 250 nm or less toward a long wavelength side of about 250 nm to 450 nm in order to improve the reaction efficiency of the photocatalyst. As a silica glass for a photocatalyst that can be converted, and at the same time, its performance does not easily deteriorate even when irradiated with ultraviolet rays for a long period of time and has excellent characteristics such as ultraviolet resistance, at least the above silica glass is used. , OH group content is 10 wt. It is ppm or less, the linear transmittance at a wavelength of 245 nm with a thickness of 10 mm is in the range of 90.0% to 30.0%, and the total content of chlorine and fluorine is 100 wt. Silica glass for photocatalyst characterized by being less than ppm has been proposed.
In recent years, the inventors of the present application have found that iron-containing soda lime silica glass prepared from recycled incineration ash discharged from municipal waste incineration facilities reduces the chemically required oxygen content (COD) of simulated wastewater, and its water. It has been reported that there is a correlation between purification activity and the local structure shown by Mesbauer spectrum analysis. (Non-Patent Documents 8 and 9) This result suggests that iron-containing soda lime silica glass acts as a photocatalyst useful for water pollution purification.
In addition, the inventors of the present application have proposed iron-containing silica glass as a glass that exhibits photocatalytic activity with visible light (Non-Patent Document 10).

JP-A-2009-154090

Fujishima A, and Honda K, (1972). Electrochemical photolysis of water at a semiconductor electrode. Nature 238, 37-38. H. Ozaki, et al, (2007) Marked Promotive Effect of Ion on Visible-Light-Induced Photocatalytic Activities of Nitrogen-and Silicon-Codoped Titanias, J. Phys. Chem. C, 11117061. Wang Z, et al., (2005), Visible-light-activated nanoparticle photocatalyst of iodine-doped titanium dioxide, Chem Mater l7 (6), 1548-1552 Khan SUM, et al, (2002), Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2, Science, 297, (5590), 2243-2245 Yanfang S, et al, (2009), Phosphorous, nitrogen and molybdenum ternary co-doped TiO2: preparation and photocatalytic activities under visible light, Journal of Sol-Gel Science and Technology, 50 (1), 98-102 Zhang D, et al., (2011), Graphite-like carbon deposited anatase TiO2 single crystals as efficient visible-light photocatalysts., Journal of Sol-Gel Science and Technology., 58 (3), 594-601 Smirnova N, et al., (2001), Synthesis and characterization of Photocatalytic Porous Fe3 + / TiO2 Layers on Glass., Journal of Sol-Gel Science and Technology., 21, 109-113 Kubuki S, et al, (2012), 57Fe Mossbauer study of iron-containing soda-lime silicate glass with COD reducing ability., American Institute of Physics Conference Proceeding Series., 1489, 41-46 Kubuki S, et al, (2012), Water Cleaning Ability and Local Structure of Iron Containing Soda-lime Silicate glass, Hyperfine Interact, 218, 41-45 Takahashi Y, et al., (2013), Visible Light Activated Photo-Catalytic Effect and Local Structure of Iron Silicate Glass Prepared by Sol-Gel Method, Hyperfine Interact, DOI: 10.1007 / s10751-013-0928-0.

However, the photocatalysts according to the proposals of Patent Document 1 and Non-Patent Documents 8 to 10 described above still have a problem that the photocatalytic activity in the visible light region is insufficient.
Further, the photocatalyst containing anatase-type titanium dioxide (Non-Patent Documents 2 to 7) has a problem that the photocatalytic activity in the visible light region is insufficient and that titanium, which is a rare metal, is used, so that the cost is high. is there.
In short, the photocatalytic glass that has been conventionally proposed does not have sufficient photocatalytic activity without using an expensive rare metal, and sufficient photocatalytic activity can be obtained without using an expensive material such as a rare metal. There is a demand for the development of photocatalytic glass.
Therefore, there is a demand for the development of a photocatalytic glass that exhibits sufficient photocatalytic activity in visible light without using rare metals, and a hematite-based photocatalytic glass has been proposed. Although this hematite-based photocatalytic glass also exhibits high catalytic activity, the current situation is that there is a demand for the development of a photocatalytic glass that has higher catalytic activity and can be easily produced.

Therefore, an object of the present invention is to provide a photocatalytic glass that does not use a rare metal, has a higher catalytic activity, and can be easily produced.

As a result of diligent studies to solve the above problems, the present inventors have found that tin can exhibit high catalytic activity in addition to iron ions, and have completed the present invention.
That is, the present invention provides the following inventions.
1. 1. A photocatalytic glass containing SnOx.SiO ₂ obtained by heat-treating a glass composition.
2. 2. 1. The photocatalytic glass according to 1, wherein the SnOx.SiO ₂ contains SnCl ₂ as a raw material component.
3. 3. A photocatalytic glass characterized by mixing tetraethyl orthosilicate and a divalent tin salt to obtain SnOx.SiO ₂ glass by a sol-gel method, and then heat-treating the obtained SnOx.SiO ₂ glass at a predetermined temperature. Manufacturing method.

The photocatalytic glass of the present invention does not use a rare metal, has higher catalytic activity, and can be easily produced.

FIG. 1 is a chart showing the results of the Mössbauer spectrum of each raw material component of the photocatalytic glass of the present invention. FIG. 2 is a chart showing the results of powder X-ray diffraction of the photocatalytic glass of the present invention. FIG. 3 is a table showing the bandgap measurement results of the photocatalytic glass of the present invention. FIG. 4 is a chart showing the photoactivity of the photocatalytic glass obtained for each raw material component. FIG. 5 is a chart showing the results of absorption analysis of the photocatalytic glass containing SnCl ₂ as a raw material and the photocatalytic glass containing Sn (COO) ₂ as a raw material. Figure 6 is a chart showing the 40Fe ₂ O ₃ · _{60P 2} results for _{O 5} powder X-ray diffraction at Reference Example. Figure 7 is a chart showing the results of FeMS in the case where the heat-treated _{40Fe 2 O 3 · 60P 2 O} 5 at 300 ° C..

Hereinafter, the present invention will be described in more detail.
The photocatalytic glass of the present invention is obtained by heat-treating a glass composition containing SnOx.SiO ₂ .
In the present specification, the photocatalytic glass refers to a glass that exhibits catalytic activity by visible light. Further, the glass includes not only glass having an amorphous structure but also crystallized glass (glass ceramic) containing a crystal component.

<Glass composition>
The glass composition used in the present invention is SnOx.SiO ₂ glass containing SnOx.SiO ₂ as an essential component.
(SnOx.SiO ₂ glass)
The SnOx.SiO ₂ glass is a so-called tin-containing silicate glass, and the content ratio of SnOx, 50 to SiO ₂ is preferably 30 to 70:70 to 30, preferably 50:50. Most preferably.
Further, x above indicates 1 or 2. That is, tin is divalent or tetravalent.
The mixing ratio of divalent tin and tetravalent tin, that is, the mixing ratio of SnO and SnO ₂ is preferably 1 to 3: 19 to 7 in terms of molar ratio. Within this range, the bandgap energy becomes a sufficiently low value, and sufficient photocatalytic activity is exhibited.
Further, the above glass can be produced by the solgel method using a divalent tin compound as described later, but the divalent tin compound as a raw material component used here (hereinafter, simply referred to as "raw material component"). (There is also), SnCl ₂ , SnF ₂ , SnO, Sn (COO) _2, etc. can be mentioned, and when used, it can be used alone or as a mixture of two or more kinds. As a raw material component, SnCl ₂ is particularly preferable because it improves the photoactivity of the obtained photocatalytic glass.

(Other ingredients)
In the glass composition of the photocatalytic glass of the present invention, in addition to the above-mentioned components, various additives can be further blended within a range not deviating from the gist of the present invention. Examples of the additive used here include a glass stabilizer and a glass modifier usually used for glass.

<Manufacturing method>
The method for producing the photocatalytic glass of the present invention will be described.
In the method for producing a photocatalytic glass of the present invention, tetraethyl orthosilicate (hereinafter referred to as "TEOS") and a divalent tin salt are mixed to obtain SnOx.SiO ₂ glass by a sol-gel method, and then the obtained SnOx. It can be carried out by heat-treating .SiO ₂ glass at a predetermined temperature.
The details will be described below.
(Production of SiO ₂ .SnOx glass)
Preparation of SiO ₂ .SnOx glass using the sol-gel method as follows was carried out by reacting TEOS and divalent tin salt.
First, a solution for hydrolysis is obtained by heating TEOS at 50 to 150 ° C. for 1 to 5 hours in the presence of an acid component of propanol and nitric acid. The raw material components then the resulting hydrolyzed solution was stirred added to a content ratio of the above, and dried at 50 to 100 ° C. 10 to 40 hours to give a SiO ₂ .SnOx glass ..
(Heat treatment)
Next, the obtained SiO _2. SnOx glass is heat-treated at 250 to 400 ° C. for 1 to 2 hours in an air atmosphere to obtain the photocatalytic glass of the present invention.

In the present invention, in addition to each of the above-mentioned steps, the production may be carried out by appropriately using other steps as needed.

<Photocatalytic glass>
In the photocatalyst glass of the present invention, tin-containing silicate glass (SnOx · SiO ₂ glass) is obtained by using a divalent tin compound as a raw material component by the sol-gel method as described above, and the obtained SnOx · SiO ₂ glass is heat-treated. SnOx · SiO ₂ glass obtained by the above.
It is considered that the photocatalytic glass of the present invention has excellent photocatalytic activity because it contains both Sn ^{2+ and} Sn ⁴⁺ . The photocatalytic activity is most excellent when SnCl ₂ is used as a raw material component, and the content ratio of Sn ^{2+ and} Sn ^{4+ in} that case is not particularly limited and is arbitrary.

<Use / effect>
The photocatalyst of the present invention has photocatalytic activity in visible light and can be used for various purposes as a photocatalyst, for example, for purification by decomposition of pollutants and the like.

The present invention is not limited to the above-described embodiment, and can be variously modified without departing from the spirit of the present invention.
The shape of the photocatalyst of the present invention is not particularly limited, and various shapes can be obtained by a known molding method such as fine particles, thin films, and fibers (wire rods). Above all, from the viewpoint of improving the catalytic activity, a large surface area is preferable, and shapes such as fine particles, thin films, and fibers are preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[Example 1]
(Production of SiO ₂ .SnOx glass)
Preparation of SiO ₂ .SnOx glass using the sol-gel method as follows was carried out by reacting TEOS and divalent tin salt.
First, a solution for hydrolysis was obtained by heating 6.7 ml of TEOS at 80 ° C. for 2 hours in the presence of 19 ml of propanol and 3.2 ml of nitric acid. 13.4 mmol of each of the raw material components shown in Table 1 was added to these and stirred to obtain four types of gels. The resulting gel was dried for 1 day at 60 ° C. respectively to obtain a SiO ₂ .SnOx glass.
(Heat treatment)
Adjusting the photocatalyst glass of SiO ₂ .SnOx glass obtained then heat-treated for 2 hours at 300 ° C..

From Mössbauer spectra, all peaks in the SiO ₂ .SnOx glass obtained from each raw material component is due to the Sn (IV) compounds, believed to be caused by oxidation of divalent tin, respectively. On the other hand, when Sn (COO) ₂ was used as a raw material component, almost no peak was observed, so it can be recognized that the Sn (IV) compound was not generated.
Also from the results of X-ray analysis, the ingredients SiO ₂ .SnOx glass with SnCl ₂ or SnF ₂ it is seen that both amorphous, particularly for _{Sn (COO) 2 Sn (COO} ) 2 particles It can be seen that is not completely dissolved and exists as a residue.
In addition, the band gap was calculated. The results are shown in Table 1. From the results shown in Table 1, it can be seen that the bandgap energies of all the raw material components were high, but the bandgap in the SiO _2. SnOx glass was increased. Further, after the heat treatment, only when SnCl ₂ was used as a raw material component, the bandgap energy was sufficiently low to show the activity in visible light.

The bandgap energy of the system using SnCl ₂ as a raw material component is shown in FIG.
Methylene blue was decomposed using the obtained photocatalytic glass, and the photocatalytic activity was confirmed. The result is shown in FIG. As a result, high photocatalytic activity was obtained especially in the photocatalytic glass using SnCl ₂ as a raw material component.
Further, the absorption spectra showing the photocatalytic activity of the photocatalytic glass using SnCl ₂ as the raw material component and the photocatalytic glass using Sn (COO) ₂ as the raw material component were measured. The result is shown in FIG. As is clear from the results, the photocatalytic glass using SnCl ₂ has a reduced amount of light absorption with and without light irradiation, and a change in the abundance of methylene blue is observed. It can be seen that in the photocatalytic glass using Sn (COO) ₂ , there is almost no change in the abundance of methylene blue, and no photocatalytic activity is observed. The difference in the amount of initial between the upper chart and the lower chart in FIG. 5 is due to the fact that the methylene blue solution was prepared separately from the system for irradiating light in order to make the graph easier to see.
Irradiation of visible light was performed at room temperature using a metal halide lamp (wavelength region 420 to 750 nm, output power 100 W, irradiation light intensity 6 mWcm- ² ). The absorbance of methylene blue was measured at room temperature, and was measured in the wavelength range of 200 to 800 nm using a UV-1700, manufactured by SHIMADZU, as an ultraviolet-visible spectrophotometer.
Mössbauer spectrum analysis, X-ray analysis analysis, and photocatalytic activity analysis were performed as follows.

[ ⁵⁷ Fe Mössbauer spectrum analysis]
Mössbauer spectrum analysis, as an analyzer, Mossbauer driving unit MDU-1200 (manufactured by Wissenschaftriche Electronics), Digital function generator DFG-1000 (manufactured by WissenschaflicheElect) (Manufactured by SEIKO), Single channel analyzer SCA-550 (manufactured by ORTEC), and Multi-Channel Analyzer MCA-7700 (manufactured by SEIKO EG & G) were connected.
As the measurement sample, the photocatalyst glass of the present invention was pulverized well, and then the pulverized product was sandwiched between cellophane tapes.
As the radiation source, ⁵⁷ Co having a dose of 925 Bq dispersed in the Rh matrix was used, and α-Fe was used as a reference substance.
The obtained spectral data was curve-fitted by fitting it to the Lorentz function using Mössbauer analysis software (trade name: MossWin3.0iXP, manufactured by Topological Systems Co., Ltd.).
The analysis was also performed on the glass obtained in the vitrification step (hereinafter, this glass may be referred to as "before annealing treatment").
The chart of the results of the obtained Mössbauer spectrum and its parameters are shown in FIG.

[X-ray diffraction]
The X-ray diffraction (XRD) analysis was performed by a sample horizontal strong X-ray diffractometer (model name: RINT-TTRIII, manufactured by Rigaku) under the following conditions.
The analysis was also performed on the glass obtained in the vitrification step (before the annealing treatment), but the results are not shown in particular.
conditions:
Diffraction angle (2θ): 10 to 80 °
Interval: 0.02 °
Scan speed: 5.0 ° min ^-1
X-ray source: CuKα ray X-ray wavelength (λ): 1.54 Å
Tube current (mA): 300
Tube voltage (kV): 50
The obtained results are shown in FIG.

[Photocatalytic activity test]
The photocatalytic activity was evaluated by a methylene blue decomposition experiment.
In the decomposition experiment of methylene blue, first, 40 mg of the photocatalytic glass of the present invention obtained in Example 1 and the heat-treated glass obtained in Comparative Example 1 were sufficiently crushed and placed in separate containers to form a 20 μM methylene blue solution. It was immersed in 10 mL, and during the immersion, visible light irradiation was performed under the following conditions.
conditions:
Device: Device name: MH-100 Illuminator (manufactured by Edmund Optics)
Light source: metal halide lamp
Filter: UV cutoff FSA filter (manufactured by Dolan-Jenner industries)
Irradiation wavelength: 420-750 nm
Output: 100W
After 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, and 180 minutes from the start of the immersion treatment, a methylene blue aqueous solution was collected from each container, and an ultraviolet visible spectrophotometer (device name: UV-1700, manufactured by SHIMADZU). The absorption spectrum was measured under the following conditions using the above.
In addition, even 3 hours after the start of the dipping treatment, a methylene blue aqueous solution is collected from each container, and an absorption spectrum is measured under the following conditions using an ultraviolet visible spectrophotometer (device name: UV-1700, manufactured by SHIMADZU). It was measured.

[Reference form]
Hereinafter, as a reference embodiment of the present invention, a catalyst glass made of iron phosphate glass will be described.
(Iron phosphate glass)
The iron phosphate glass of this reference form is amorphous, and is a glass in which Fe ²⁺ ions and Fe ³⁺ ions are mixed in the glass. In addition, the substances containing Fe ²⁺ ions form an octahedral network.
The mixing ratio of Fe ²⁺ ions and Fe ³⁺ ions is not particularly limited.
Specific examples of the iron phosphate glass, may be mentioned _{40Fe 2 O 3 · 60P 2 O} 5, 50Fe 2 O 3 · 50P 2 O 5 or the like.
Further, FeO can be mentioned as a substance containing Fe ²⁺ ions contained in the iron phosphate glass, and Fe ₂ O ₃ can be mentioned as a substance containing Fe ³⁺ ions, both of which are mixed. Examples of the resulting substance include Fe ₃ O ₄ .
The catalyst glass of the present reference embodiment may contain components other than the iron phosphate glass as long as the effects of the iron phosphate glass are not impaired.
(Production method)
The iron phosphate glass of this reference form can be produced by the so-called sol-gel method.
For example, first, a conventional method, after adjusting the _{40Fe 2 O 3 · 60P 2 O} 5 or the like of the gel, dried 100 to 400 hours at a temperature of the resulting gel low temperature (50 to 150 ° C.), further 200 The iron phosphate glass can be obtained by performing heat treatment at a temperature of about 500 ° C. for 3 to 20 hours.

[Reference Example]
1.80 g of P ₂ O ₅ was added to 10.4 mL of reagent special grade i-CH ₃ CH (OH) CH _3, and the mixture was refluxed at 90 ° C. for 3 hours. Next, a mixed solution of i-CH ₃ CH (OH) CH ₃ , C ₂ H ₅ OH, H ₂ O, and HCl (7.8 M) (2.6 mL, 2.6 mL, 2 respectively) while refluxing at 60 ° C. A mixed solution of 9.0 mL and 3.5 mL) was added dropwise, and the mixture was stirred for 2 hours. Thereafter, stirring while the water bath at _{20 ℃, Fe (NO 3)} 3 · 9H 2 O was completely dissolved by adding _6.82g, and the mixture was stirred for 2 hours was added dropwise CH ₃ CHCH 2 O7.5mL. Then refluxed for 2 hours at 60 ° C., to obtain a gel of _{40Fe 2 O 3 · 60p 2 O} 5. The obtained gel was allowed to stand at room temperature for 4 days. Then it was dried. Drying was carried out by first raising the temperature to 80 ° C. over 48 hours in an electric furnace and holding it for 48 hours.
_{Thereafter, 40Fe 2 O 3 · 60P 2} O 5 and heating rate ^50Kh -1, was heat-treated at 200 to 500 ° C.. Structural analysis is Mössbauer spectroscopic analysis (FeMS (source: ⁵⁷ Co (Rh), reference: α-Fe)), powder X-ray diffraction (XRD (target: Cu-K _, 2θ: 10-80 °, voltage: 50 kV). , Current: 300mA)).
Moreover, the temperature dependence (2 to 300K) of the magnetic susceptibility under a DC magnetic field (500Oe) was measured, and the magnetic properties were evaluated.
FIG. 6 shows the XRD results of the obtained iron phosphate glass. When heat-treated at 300 ° C., it showed a halo pattern and was found to be amorphous.
FIG. 7 shows the results of FeMS when the iron phosphate glass obtained was heat-treated at 300 ° C. From the obtained spectrum, an isomer shift (δ) = 1.11 mms ^-1 belonging to the octahedral Fe ²⁺ , a quadrupole split (QS) = 2.38 mms ^-1 , and a doublet of Fe ^3+. found that [delta] = 0.29 ^mms -1 attributable, Q.S. = 0.75 doublet of ^{mms -1} is obtained, two types of ^{Fe 2+} and ^{Fe 3+} ions in the glass are mixed in It was.

Since the photocatalytic glass of the present invention exhibits sufficient photocatalytic activity in visible light, it can be used as various catalysts, and can also be applied to solar panels, optical fibers, and the like.
It is also considered possible to manufacture the photocatalyst glass of the present invention using fly ash discharged from the blast furnace of an electric power manufacturer as a raw material, and tin, which is indispensable for manufacturing flat glass, is effective. Since it is possible to utilize waste glass, it is possible to recycle inorganic waste such as incineration ash discharged from various facilities as the photocatalyst glass of the present invention. In addition, the main component is silicate glass, and natural "waste" such as volcanic ash, which is difficult to process, can be effectively utilized.

Claims (1)

Consisting of SnCl ₂ as a raw material component SnOx.SiO ₂ to (x in the formula is 1 or 2) as a raw material, a method for producing a photocatalyst glass comprising a tetravalent Sn,
A solution for hydrolysis was obtained by heating tetraethyl orthosilicate at 50 to 150 ° C. for 1 to 5 hours in the presence of an acid component, and SnCl ₂ was mixed with the obtained solution for hydrolysis by a sol-gel method. A method for producing a photocatalytic glass, which comprises obtaining SnOx.SiO ₂ and then heat-treating the obtained SnOx.SiO ₂ at 250 to 400 ° C. for 1 to 2 hours.