JP6521317B2 - Metal complexed carbon nitride for deodorization and manufacturing method thereof - Google Patents

Description

  The present invention relates to a novel method for producing metal-complexed graphitic carbon nitride supporting a metal, a novel metal-complexed graphitic carbon nitride excellent in adsorption performance of odorous substances and photocatalytic function, and the novel metal complexation The present invention relates to a deodorizing agent and a deodorizing apparatus using graphitic carbon nitride.

As one of the deodorizing techniques for oxidizing and degrading offensive odor substances present in the living environment, there is a method using titanium oxide as a photocatalyst, but titanium oxide works only when it is exposed to ultraviolet light, and sunlight and indoors I could not use visible light, which is often contained in light.
In recent years, a method using tungsten oxide that responds to visible light as a photocatalyst has also been developed, but tungsten is more expensive (about 10 times) than titanium oxide, and supplies are unstable because it is a strategic substance. There's a problem.

Graphitic carbon nitride (g-C ₃ N ₄₎ is a melamine or cyanamide can be easily synthesized by thermal decomposition, it has become known in recent years that acts as a photocatalyst responsive to visible light (non-patent literature 1, 2). Graphite-like carbon nitride is less expensive than tungsten oxide and the like, and it is a merit that supply is stable.

  However, even if graphite-like carbon nitride synthesized by thermal decomposition of melamine or cyanamide is used as it is, its photocatalytic performance is low and it is far from practical use in air purification and deodorizing applications. Therefore, various methods for improving the performance have been studied, and methods of increasing the specific surface area by hydrothermal treatment to improve the air purification performance (Patent Document 1 etc.) and methods of including metal in the interlayer of graphitic carbon nitride ( Patent Documents 2, 3 and Non-patent Document 3) have been found, and the performance as a photocatalyst for air purification has been gradually improved. However, the adsorptive power and decomposition performance to sulfur compounds such as methyl mercaptan which are important as an offensive odor substance are still low, and improvements have been necessary.

  As a method of improving the adsorption performance of a catalyst or an adsorbent to a sulfur compound, there is a method of supporting a metal such as silver by an impregnation method or a photo electrodeposition method. When silver is supported, it is known that the adsorption performance of graphite-like carbon nitride is improved by supporting silver. Although many metals can not be supported by the impregnation method, while relatively large metals can be supported by the photo-electrodeposition method, the amount of adsorption per unit weight of silver decreases rather as the amount of silver is increased, and silver is effective. It was not possible to use it.

JP, 2011-195412, A International Publication No. 2011/049085 JP-A-2-308815

WANG Xinchen, et al. “Polymer Semiconductors for Artificial Photosynthesis: Hydrogen Evolution by Mesoporous Graphitic Carbon Nitride with Visible Light” J Am Chem Soc Vol. 131, No. 5, Page. 1680-1681 (2009.02.11) WANG Xinchen, et al. “A metal-free polymeric photocatalyst for hydrogen production from water under visible light” Nat Mater Vol. 8, No. 1, Page. 76-80 (2009.01) Kazuhiko Maeda "5 Photocatalytic activities of carbon nitride (C3N4) under visible light irradiation" Catalysts Discussion Group A Proceedings Vol. 102nd, Page. 126 (2008.09.23)

The present invention has been made against the background art as described above, and is capable of expecting various functions and properties depending on the metal to be supported, and it is a relatively low-cost and simple process for metal-complexed graphitic carbon nitride. It is an object of the present invention to provide a novel manufacturing method that can be manufactured by
The present invention also provides a novel production method capable of producing metal complexed graphitic carbon nitride having deodorizing performance and / or photocatalytic function of malodorous substances such as sulfur compounds by a relatively low cost and simple process. As an additional task.
In addition, the present invention is relatively low in cost and excellent in the ability to adsorb malodorous substances such as sulfur compounds, and also has the property of oxidizing and degrading malodorous substances by irradiation with visible light and ultraviolet light at relatively low cost. It is an additional task to provide a novel manufacturing method that can be manufactured by a simple process.
Another object of the present invention is to provide a novel metal-complexed graphitic carbon nitride having deodorizing performance and / or photocatalytic function of malodorous substances such as sulfur compounds.
Another object of the present invention is to provide a novel metal-complexed graphitic carbon nitride that is excellent in the adsorption performance of malodorous substances such as sulfur compounds and has the property of oxidizing and degrading malodorous substances by irradiation with visible light or ultraviolet light. I assume.

The following findings were acquired in the process of advancing various test researches under the above-mentioned subject.
(1) A metal complex supported carbon nitride carrying metal is manufactured by a relatively low cost and simple process of performing high shear treatment of graphitic carbon nitride in a solution containing metal ions at a predetermined stirring peripheral speed or higher. be able to.
(2) In the above-mentioned production, by adjusting the kind and the loading amount of the metal, it is possible to obtain metal composite carbon nitride having a high adsorbing ability to an odorous substance such as a sulfur compound and a high photocatalyst removal rate.
(3) graphitic carbon nitride and nitrogen-containing organic compounds have been prepared by thermal decomposition, such as melamine and cyanamide (hereinafter referred to as "g-C ₃ N _4".) Ya advance in alkaline aqueous solution such as sodium hydroxide If the specific surface area of g-C ₃ N ₄ is increased by performing hydrothermal treatment in an acidic aqueous solution, the adsorption capacity and the photocatalyst removal rate can be improved.
(4) Gold, silver, copper nitrates, acetates, acetylacetonate complexes and the like can be used as the raw material of metal ions, but silver acetate provides significantly higher adsorption performance. Even with the addition of about 24% by weight silver, the adsorption performance per silver atom is higher than in the case of 1% by weight in the conventional method.
(5) It is considered that the supported metal particles do not move on the surface of the graphitic carbon nitride before and after adsorption of an offensive substance such as a sulfur compound when manufactured by the conventional photo electrodeposition method. In the case of those manufactured by shear processing, the supported metal particles have relatively weak cohesion and relatively weak bonding to graphitic carbon nitride, and further bonding and cohesion along with adsorption of odorous substances such as sulfur compounds. It is thought that it decreases and changes to a plate-like shape, and the proportion of the surface increases. As a result, in the products manufactured by the high shear treatment of the present invention, the adsorption capacity and the photocatalytic removal rate of malodorous substances such as sulfur compounds are larger than those by the photo electrodeposition method by setting the kind and amount of metal to be supported. It can be improved and can be an excellent adsorbent for malodorous substances.

The present invention has been completed based on the above-described findings, and the present invention provides the following inventions.
<1> A method for producing metal-complexed graphitic carbon nitride, characterized in that the powder of graphitic carbon nitride is subjected to high shear treatment at a stirring peripheral speed of 2 m / s or more in a solution containing metal ions.
<2> The method for producing metal-complexed graphitic carbon nitride according to <1>, wherein the powder of graphitic carbon nitride is previously subjected to a hydrothermal treatment in an alkaline aqueous solution or an acidic aqueous solution.
The manufacturing method of metal complex-ized graphitic carbon nitride as described in <1> or <2> whose metal of <3> above-mentioned metal ion is 1 type or multiple types selected from silver, gold | metal | money, and copper.
<4> The method for producing metal-complexed graphitic carbon nitride according to any one of <1> to <3>, wherein the metal has a weight ratio of 10% or more to metal-complexed graphitic carbon nitride .
The metal-complexed graphitic carbon according to any one of <1> to <4>, wherein the solution containing a <5> metal ion is a solution containing a metal inorganic salt, a metal organic salt, or a metal organic complex Manufacturing method.
<6> A metal-complexed graphitic carbon nitride in which one or more metals selected from silver, gold and copper are complexed to graphitic carbon nitride, and the supported amount of the metal is 10% by weight or more A metal-complexed graphitic carbon nitride, characterized in that the metal is movably complexed upon adsorption of methyl mercaptan.
<7> A metal complexed graphitic carbon nitride in which silver is complexed to graphitic carbon nitride, and the supported amount of the silver is 10% by weight or more, and the specific surface area of the silver is 500 m ² / g A metal complexed graphitic carbon nitride characterized by the above.
The deodorizer which has <8> adsorption performance and photocatalytic performance, and uses metal complex-ized graphitic carbon nitride as described in <6> or <7> as an active ingredient.
The deodorizing apparatus which comprises the deodorizing agent as described in <9><8>.

The present invention can include the following aspects.
The manufacturing method of metal complex-ized graphitic carbon nitride as described in any one of <1>-<5> whose <10> stirring peripheral speed is 2.5-12 m / s.
<11> The metal-complexed graphite-like nitride according to any one of <1> to <5>, <10>, wherein the metal is 10 to 35% by weight ratio to the metal-complexed graphite-like carbon nitride How to make carbon.
<12> The metal composite according to any one of <1> to <5>, <10>, <11>, wherein the graphitic carbon nitride powder to be mixed is synthesized by thermal decomposition of melamine or cyanamide Method of carbonized graphite-like carbon nitride.
Metal-complexed graphitic carbon nitride according to <6> or <7>, wherein the amount of supported <13> metal is 11 to 33% by weight.
The metal complexing graphitic carbon nitride as described in <6>, <7> or <13> whose adsorption capacity of <14> methyl mercaptan is 300 micromol / g or more.
The deodorizer which has <15> adsorption performance and photocatalytic performance, and uses metal complex-ized graphitic carbon nitride as described in <13> or <14> as an active ingredient.
The deodorizing apparatus which comprises the deodorizing agent as described in <16><15>.

According to the manufacturing method of the present invention, metal-complexed graphitic carbon nitride which can be expected to have various functions and properties depending on the metal to be supported can be manufactured by a relatively low cost and simple process.
In addition, according to the production method of the present invention, metal complexing graphitic carbon nitride having a deodorizing performance and a photocatalytic function of an offensive odor substance such as a sulfur compound is relatively low by appropriately setting the kind and the loading amount of metal. It can be manufactured in a cost and simple process.
The deodorizing carbon nitride of the present invention is an adsorbent excellent in the adsorption performance of an offensive odor substance, and has the property of oxidizing and degrading the offensive odor substance by irradiation with visible light or ultraviolet light.

It shows the change in X-ray diffraction diagram of the course of synthesizing the Ag carrying graphitic carbon nitride _{(Ag / g-C 3 N} 4 or _{Ag / HT-g-C 3} N 4) melamine. Electron micrograph of graphitic carbon nitride carrying Ag by high shear treatment. (a) shows methyl mercaptan (MM) adsorption before, and (b) shows MM adsorption after. The figure which shows the change of the peak of silver (Ag3d) of the X-ray-photoelectron spectroscopy by methyl mercaptan (MM) adsorption and visible light irradiation of Ag carrying | support graphitic carbon nitride. (a) shows before MM adsorption, (b) shows after MM adsorption, and (c) shows after MM irradiation followed by irradiation with visible light. The schematic diagram which shows the apparatus which analyzes the deodorizing performance used in the Example of this invention. The figure which shows the adsorption of methyl mercaptan by graphitic carbon nitride which carry | supported silver by high shear processing, and the profile of the photocatalytic decomposition by irradiation of visible light. The figure which showed the silver supporting amount dependence of the adsorption capacity and photocatalyst removal rate of Ag carrying | support graphitic carbon nitride. □ indicates the high shear treatment method of the example of the present invention, and ○ indicates the light electrodeposition method of the comparative example.

The method for producing metal-complexed graphitic carbon nitride according to the present invention is characterized in that the powder of graphitic carbon nitride is subjected to high shear treatment with a stirring peripheral speed of 2 m / s or more in a solution containing metal ions. is there. According to the manufacturing method of the present invention, it is possible to manufacture metal complexed graphitic carbon nitride having a relatively large metal loading amount as compared with the conventional impregnation method by a relatively low cost and simple process as compared with the conventional photo electrodeposition method. Can.
By subjecting graphitic carbon nitride to high shear treatment in a solution containing metal ions, in the case of easily reducing metal ions, at least a portion of the metal ions are reduced and precipitated and dispersed and supported on the graphitic carbon nitride Be done. In addition, in the case of a metal ion which is difficult to reduce, a part of the metal ion is deposited and dispersed and supported on the graphitic carbon nitride. It is assumed that the metal-complexed graphitic carbon nitride to be produced exhibits various functions and properties which can not be obtained by graphitic carbon nitride alone, depending on the metal to be supported.

  The powder of graphitic carbon nitride used for the preparation is not limited and includes those synthesized by thermal decomposition of melamine, cyanamide, dicyandiamide, urea, triazine, triazine chloride, cyanuric acid etc., or a mixture thereof . The powder to be used is not limited, but usually, the average particle diameter is about 1 to 30 μm.

  The graphitic carbon nitride powder is desirably pre-hydrothermally treated in an aqueous alkali solution or an acidic aqueous solution so as to increase the specific surface area. The alkaline hydrothermal treatment is carried out by adding graphitic carbon nitride in an aqueous solution containing sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and the like at a concentration of 0.05 to 0.2 mol / l and stirring at 70 to 150 ° C. This can be done by heating to The acid hydrothermal treatment may be carried out by heating graphitized carbon nitride in an aqueous solution containing hydrochloric acid, nitric acid, sulfuric acid, etc. having a concentration of 0.05 to 0.2 mol / l and stirring to 130 to 170 ° C. while stirring. it can.

The metal supported on the graphitic carbon nitride includes, but is not limited to, silver, gold, copper, platinum, palladium, nickel, iridium, rhodium, osmium, ruthenium, iron, cobalt, manganese, molybdenum, zinc, etc. It can be mentioned.
When a metal complexed graphitic carbon nitride is expected to have a photocatalytic function, it is not limited to silver, gold, copper, platinum, palladium, palladium, nickel, iridium, rhodium, osmium, ruthenium, iron, cobalt and the like. Be
When metal complexed graphitic carbon nitride is expected to have both photocatalytic function and adsorption performance to sulfur compounds etc., silver, gold, copper, nickel etc. may be mentioned, preferably silver, gold, especially silver preferable.

  The amount of the metal supported on the metal-complexed graphite carbon nitride is not limited, but is determined according to the degree of the function or property to be obtained. Usually, it is 5% by weight or more, preferably 10% by weight or more, more preferably 12% by weight or more, which is larger than the conventional impregnation method. The upper limit is not limited, but is usually 35% by weight or less, preferably 33% by weight or less, and more preferably 30% by weight or less.

In the present invention, high shear treatment means mixing by stirring with a stirring peripheral speed of 2 m / s or more, preferably 3 m / s or more, more preferably 5 m / s or more. The upper limit of the stirring peripheral speed is the upper limit performance of the stirring device, and is usually 50 m / s or less, preferably 20 m / s or less, more preferably 10 m / s or less.
The stirring apparatus used for high shear processing is not limited, and commercially available homogenizers, mixers, blenders and the like can be used.
In addition, since a general magnetic stirrer is usually used at about 100 to 500 rotations / minute, when the length of the stirrer is 25 mm and 500 rotations / minute, the stirring peripheral speed is 0.65 m / s (= 0.25) m × π × 500/60 seconds), which is 1/3 or less of the lower limit of the stirring peripheral speed range of the present invention.

  Examples of the solution containing metal ions include solutions containing metal inorganic salts, metal organic salts, and metal complexes. The metal inorganic acid salts include, but are not limited to, nitrates, sulfates, hydrochloride carbonates, phosphates and the like, preferably nitrates and hydrochlorides, and more preferably nitrates. Further, examples of the metal organic acid salt include acetate, citrate, formate and oxalate, and examples of the metal complex include acetylacetonate complex, EDTA complex, ammine complex, hydro complex and the like.

  The temperature of the solution used for the high shear treatment can be, but is not limited to, normal temperature. The temperature of the solution rises to, for example, about 70 ° C. during the high shear treatment, but the metal can be supported either by cooling or as it is.

The metal-complexed graphitic carbon nitride of the present invention manufactured by the high shear processing as described above has a metal content ratio compared to the metal-complexed graphitic carbon nitride manufactured by stirring treatment with a conventional magnetic stirrer. You can do more.
When comparing the metal-complexed graphitic carbon nitride of the present invention with the metal-complexed graphitic carbon nitride produced by the conventional photo-electrodeposition method, there is not much difference in terms of the amount of metal supported, It is considered that the state of metal support on carbon is largely different. In the conventional photo-electrodeposition method, the supported metal particles have relatively strong cohesion and are also relatively strongly bonded to graphitic carbon nitride, and are graphitic before and after adsorption of odorous substances such as sulfur compounds. It is believed not to move on the carbon nitride surface. On the other hand, in the one produced by the high shear treatment of the present invention, the supporting metal particles have relatively weak cohesive power and relatively weak binding power to the graphitic carbon nitride, accompanied by the adsorption of offensive odor substances such as sulfur compounds. It is considered that the cohesion and cohesion further decrease and change to a plate-like shape (primary particles move like a plate-like), and the ratio of the surface increases. As a result, in the products manufactured by the high shear treatment of the present invention, the adsorption capacity and the photocatalytic removal rate of malodorous substances such as sulfur compounds are larger than those by the photo electrodeposition method by setting the kind and amount of metal to be supported. It can be improved and can be an excellent adsorbent for malodorous substances.

  Hereinafter, the present invention will be described based on examples and the like, but the present invention is not limited to the examples and the like.

Reference Example 1 Production of Graphitic Carbon Nitride Powder
Graphitic carbon nitride (hereinafter referred to as g-C ₃ N ₄ ) was synthesized as follows.
30 g of melamine (manufactured by Wako Pure Chemical Industries, Ltd.) is put in a crucible made of alumina, covered, fired in an electric furnace at 550 ° C. for 1 hour, ground in a mortar, and put again in the crucible for another 1 hour 550 It baked at ° C. The resulting yellow powder was ground in a mortar to obtain g-C ₃ N ₄ powder. As a result of elemental analysis, the C / N ratio was 0.67, which is polyheptadine (C ₆ N ₉ H ₃ ) among substances collectively referred to as graphitic carbon nitride (g-C ₃ N ₄ ). The result of X-ray diffraction also showed that it is polyheptadine. Incidentally, even when cyanamide is used as a raw material of carbon nitride, since substantially the same result is obtained, a raw material of carbon nitride other than melamine may be used. The median of the pore size distribution of g-C ₃ N ₄ determined by the adsorption of nitrogen molecules at liquid nitrogen temperature was around 30 to 50 nm.

(Reference example 2: Alkaline hydrothermal treatment of g-C ₃ N ₄ )
1.0 g of the above-mentioned g-C ₃ N ₄ powder, 0.40 g of sodium hydroxide and 90 ml of water are put into a Teflon crucible and stirred. The sodium hydroxide concentration at this time is 0.11 mol / l. The Teflon (registered trademark) crucible was placed in a stainless steel jacket, and heated at 110 ° C. while stirring with a magnetic stirrer. The temperature was measured using a thermocouple at the bottom of the stainless steel jacket. After heating for 18 hours, it was allowed to cool to room temperature. The suspension in the Teflon crucible was centrifuged to obtain a precipitate. Add 30 ml of water to the precipitate, stir, and repeat the process of washing the precipitate with water several times by centrifuging (20 minutes at 14500 G) with an ultracentrifuge (Kubota micro cooling centrifuge model 3700). to obtain a heat-treated graphitic carbon nitride _{(HT-g-C 3 N} 4). The specific surface area before the alkaline hydrothermal treatment was about 8 m ² / g, but increased to 50 m ² / g after the treatment. The median pore size distribution of the HT-g-C ₃ N ₄ obtained by adsorption of nitrogen molecules in the liquid nitrogen temperature were present in the vicinity of 3 to 8 nm.

<Production of metal complexed graphitic carbon nitride>
(Comparative Example 1: metal supported by impregnation to the g-C ₃ N ₄ or _{HT-g-C 3 N 4} )
After mixing with g-C ₃ N ₄ or HT-g-C ₃ N ₄ powder 0.40g of the silver nitrate aqueous solution 0.80ml containing silver 0.040 g, removing water at 100 ° C.. The mixture was further mixed using an agate mortar, placed in an alumina crucible, covered, and heated in air at 450 ° C. for 1 hour using an electric furnace. After allowing to cool, it was ground again in an agate mortar to obtain silver-supported g-C ₃ N ₄ or HT-g-C ₃ N ₄ .

(Comparative Example 2: Metal-supported by the optical electrodeposition method to g-C ₃ N ₄ or _{HT-g-C 3 N 4} )
0.20 g of the above gC ₃ N ₄ or HT-g C ₃ N ₄ powder is placed in a glass container with a quartz lid, and 30 mL of an aqueous silver nitrate solution containing 0.00274 g to 0.0648 g of silver is added Suspend. While passing nitrogen gas at a flow rate of 50 mL / min and stirring with a magnetic stirrer (agitating peripheral speed about 0.5 m / s), passing through a quartz lid of an ultra-high pressure mercury lamp (Ushio, USH-500 D, 500 W) The light was irradiated for 30 minutes to precipitate silver on carbon nitride. Water was washed three times with 30 mL of water, samples were collected using a centrifuge (20 min at 14500 G) and finally dried overnight at 80 ° C.

(Example 1: g-C ₃ N ₄ or a metal supported by high shear processing of the _{HT-g-C 3 N 4} )
0.20 g of the above gC ₃ N ₄ powder or HT-g C ₃ N ₄ powder, 0.10 g of silver acetate and 10 ml of water are put in a glass test tube of 20 mm in diameter, and an ultrasonic generator is used Then, silver acetate was dissolved. The silver ion concentration at this time is 0.06 mol / l. A rotary homogenizer (ADU manufactured by As One ADG-160D) having a rotary blade with an outer diameter of 13 mm in a head having a fixed external tooth with a diameter of 18 mm is installed 5 mm above the bottom of the test tube, 10000 rpm or 5000 rpm. High shear treatment [Stirring peripheral velocity = 0.013 (m) × π × 10000/60 (seconds) = 6.8 m / s or 0.013 (m) × π × 5000/60 (seconds) = 3.4 m / s] I did it for 70 minutes. Further, the high shear treatment was performed in the same manner as described above except that the rotational speed was changed to 15000 rpm (agitating circumferential speed 10.2 m / s) for 10 minutes. The suspension in the test tube was centrifuged (20 minutes at 14500 G) in an ultracentrifuge (manufactured by Kubota Micro Cooled Centrifuge Model 3700) to obtain a precipitate. The precipitate was added with 30ml of water and stirred to obtain by centrifugal separation again, to remove impurities from the precipitate, the g-C ₃ N ₄ which is supported silver or HT-g-C ₃ N ₄ The Respectively referred to as Ag / g-C ₃ N ₄ or _{Ag / HT-g-C 3} N 4. When not silver acetate but silver nitrate was used as a silver precursor, 0.11 g of silver nitrate was used. The weight ratio of silver in the resulting powder is about 24.4%.
When supporting metals other than silver, 0.20 g of gC ₃ N ₄ powder, metal nitrate or metal acetate containing metal ions to be supported, and 10 ml of water are placed in a glass test tube, and ultrasonic wave is generated. The metal salt was dissolved using a vessel. High shear treatment (agitation circumferential speed = 6.8 m / s) was performed for 40 minutes using a rotary homogenizer (ADG-160D manufactured by As One Corporation) having a head with a diameter of 18 mm and rotating at 10000 rpm. The suspension in the test tube was centrifuged (20 minutes at 14500 G) in an ultracentrifuge (manufactured by Kubota Micro Cooled Centrifuge Model 3700) to obtain a precipitate. Add 30 ml of water to the precipitate, stir, remove impurities from the precipitate by centrifuging again and use g-C ₃ N ₄ or HT-g-C ₃ N ₄ with the target metal supported. I got
The amount of the metal salt to be added was appropriately adjusted such that the weight of the supported metal was 1 to 32.4% with respect to the metal complexed graphitic carbon nitride.

FIG. 1 shows g-C ₃ N ₄ synthesized by the method of Reference Example 1 described in [0024], HT-g-C ₃ N ₄ synthesized by the method of Reference Example 2 described in [0025], [0028] is a diagram showing the X-ray diffraction pattern of example 1 Ag / g-C ₃ carrying silver method N ₄ and _{Ag / HT-g-C 3} N 4 according to. The main peak around 27.4 ° and unclear diffraction from 12 to 25 ° can be confirmed. The average of the layer spacing of g-C ₃ N ₄ was calculated to be about 3.3 Å from the position of the main peak, and it was confirmed that it was g-C ₃ N ₄ conventionally known. The pattern of HT-g-C ₃ N ₄ treated with alkaline hydrothermal treatment was not significantly different from that before hydrothermal treatment.
When high shear treatment was performed in an aqueous solution of silver acetate, the intensity of the main peak at 27.4 ° decreased, and no diffraction at 12 to 25 ° could be confirmed. The decrease of the peak observed here is due to the interaction between the silver ion and the graphitic carbon nitride that the layer spacing is not constant at 3.3 Å and the diffraction is weakened due to the disorder of the periodic structure. No peak of silver was observed, suggesting that silver is highly dispersed.

It shows a scanning electron micrograph of the resulting _{Ag / HT-g-C 3} N 4 in a high shear process in FIG. It was confirmed that, even though a large amount of silver was added, it was supported on graphitic carbon nitride as silver nanoparticles having a particle size [= (long diameter + short diameter) / 2] of about 5 nm to 30 nm.

As a result of analyzing the distribution of elements by energy dispersive X-ray analysis (not shown) for Ag / HT-g-C ₃ N ₄ obtained by high shear treatment, silver reduced to the whole of graphitic carbon nitride Was confirmed to be carried. In addition, as a result of analyzing the contents of silver and oxygen by X-ray photoelectron spectroscopy, it was confirmed that the reduced silver was supported.

<Example 2, Comparative Example 3: Measurement of deodorizing performance of metal complexed carbon nitride>
FIG. 4 is a view showing an apparatus for analyzing the deodorizing performance, which is based on the measuring apparatus described in JIS R1751-1 used for measuring the decomposing performance of an offensive odor substance by the photocatalyst. Deodorizing performance was measured as follows according to JIS R1751-5 using this device.

0.10 g of the metal-supported graphitic carbon nitride sample is suspended in about 1 ml of water, the whole is applied to a glass plate of 50 mm in width and 100 mm in length, dried at 50 ° C., and subjected to a photocatalyst (Photocatalyst) test A piece was prepared. The test piece is placed in the photocatalytic reaction vessel shown in FIG. 4, covered with a borosilicate glass cover window, and covered with a cover so that light does not reach the photocatalyst.
Simulated contaminated air containing 5 ppm of methyl mercaptan and having a relative humidity of 50% (25 ° C.) is prepared by a mass flow controller, and is allowed to flow through the bypass at a flow rate of 0.50 L / min. The concentration of methyl mercaptan (MM) in the simulated polluted air is measured with a gas chromatograph (GC-14B manufactured by Shimadzu Corporation) equipped with a hydrogen flame ionization detector (FID). After the methyl mercaptan concentration, humidity, and flow rate are stabilized, the valve is switched to flow simulated contaminated air in the photocatalytic reaction vessel. The MM and dimethyl disulfide (DMDS) coming out of the reaction vessel are measured by gas chromatography. When the specimen adsorbs MM, the MM concentration decreases, and then the adsorption rate decreases as MM covers the silver surface, and the concentration gradually increases. The amount of adsorption up to more than 4.5 ppm is determined by calculation, and is defined as MM adsorption amount. Moreover, let the adsorption amount per 1 g of sample powder be an adsorption capacity.
After the amount of increase in the MM concentration decreases, the sample is irradiated with light to initiate photocatalytic reaction. The illuminance was set to 6000 Lx using a white fluorescent lamp (FL10W manufactured by Toshiba) as a light source, and the ultraviolet light contained in the light of the fluorescent lamp was removed using an ultraviolet light removal filter (N-169 manufactured by Nitto Resin Kogyo Co., Ltd.). [MM concentration at the time of bypass]-[MM concentration at the outlet of the reaction vessel when irradiated with light]} / {[MM concentration at the time of bypass]} × 100 was taken as the MM removal rate.

Figure 5 shows the results of a deodorizing performance evaluation test using the _{Ag / HT-g-C 3} N 4. When the simulated contaminated air was brought into contact with the sample, the MM concentration dropped sharply to 0.2 ppm. After several hours, the MM concentration started to increase and reached 4.5 ppm over 48 hours. When irradiated with light, the MM concentration decreased to 0.3 ppm, and it was confirmed that the visible light could remove the MM. Even after 100 hours of light irradiation, 50% or more of the MM was removed.

In Table 1, as a deodorization test result by metal complexed graphitic carbon nitride supporting metal and unsupported graphitic carbon nitride, preparation method (metal deposition method), supported amount [metal to metal complexed graphitic carbon nitride] Supported amount (% by weight)], specific surface area [specific surface area of metal complexed carbon nitride (m ² / g)], adsorption capacity (μmol / g), metal specific surface area (m ² / g), photocatalyst removal rate [light The average MM removal rate (%) up to 3 hours after irradiation was shown.
In addition, the multipoint BET method which used nitrogen as an adsorbate was utilized for the measurement of the specific surface area of graphite-like carbon nitride or metal complexed graphite-like carbon nitride. Japan Bel-made Belsorp-Max was used for the measurement. About 0.1 g of a sample was placed in a sample holder, and after degassing at 120 ° C. for 3 hours, the specific surface area was measured.
In addition, the specific surface area of the metal is as follows: (1) All the metal particles supported on the graphitic carbon nitride are spheres of the same diameter, (2) MM of adsorption capacity measured on the entire surface of the supported metal particles (3) The adsorption area of 1 MM molecule is 22.4 Å (0.224 nm ² ) (refer to Miyoshi Yasushi 2 people, Industrial Medicine 19: 2-7 (1977) table 4.) Calculated based on

As apparent from Table 1, it was found that graphitic carbon nitride not supporting metal hardly adsorbs MM, exhibits a low adsorption capacity, has a low photocatalyst removal rate, and has a low deodorizing performance. When silver nitrate is used as a precursor by conventional impregnation method or photo electrodeposition method, adsorption capacity and photocatalyst removal rate are increased. When 1% by weight silver was supported on HT-g-C ₃ N ₄ by the photo electrodeposition method, an adsorption capacity of 21 μmol / g and a photocatalyst removal rate of 49% were obtained.
When the silver loading amount was increased to 24.4%, the adsorption capacity increased to 340 μmol / g, but the silver adsorption amount per unit weight decreased. In addition, the metal specific surface area important for adsorption also decreased.
When silver was supported at a weight ratio of 24.4% by the high shear processing method, an adsorption capacity of three or more times as high as in the case of the optical electrodeposition method was obtained. Further, even with the same high shear treatment method, when silver acetate was used as a precursor, an adsorption capacity of 1.5 times and a photocatalyst removal rate higher by 10% or more than in the case of silver nitrate were obtained. The average number of MM molecules that can be adsorbed per silver atom was 0.59 in the high shear processing method and 0.14 in the photo electrodeposition method. It has been found that high shear processing can form silver particles that favor the adsorption of MM.
Further, even when g-C ₃ N ₄ which was not subjected to alkaline hydrothermal treatment was used, when 24.4% of silver was supported by the high shear treatment method, a high adsorption capacity of 691 μmol / g was exhibited. Moreover, it was confirmed that the specific surface area is increased by the high shear treatment. Better results than conventional silver loading methods were obtained without adding alkaline hydrothermal treatment to graphitic carbon nitride beforehand. However, the best results were obtained when silver was supported by high shear treatment on graphitic carbon nitride (HT-g-C ₃ N ₄ ) whose specific surface area was increased by alkaline hydrothermal treatment.
Gold and copper can also be supported by the high shear processing method, and a significantly higher adsorption capacity and photocatalyst removal rate are obtained than when metal is not added or copper is supported by the photo electrodeposition method. There was no effect on iron loading.
A similar test was conducted by loading 24.4% of silver on titanium oxide conventionally known as a photocatalyst, and an adsorption capacity of 79 μmol / g and a photocatalyst removal rate of 55% were obtained. All the values were significantly lower than that of graphitic carbon nitride supported by silver by the high shear treatment method.

FIG. 2 (b) shows an electron micrograph of the silver-supported HT-g-C ₃ N ₄ of the example after MM adsorption. A band-like shape is observed from the shape of a sphere or a hemisphere before MM adsorption, or a shape close to them.
FIG. 3 shows the change of the peak of silver (Ag 3 d) in X-ray photoelectron spectroscopy by MM adsorption of silver-supporting HT-g-C ₃ N ₄ and irradiation with visible light. The peak of silver (Ag 3 d) is enlarged after MM adsorption, and it is assumed that the aggregate having a small proportion of the surface before MM adsorption is changed to a flat plate shape having a large proportion of the surface.
For silver bearing HT-g-C ₃ N ₄ by the optical electrodeposition method of the comparative example, (not shown) resulted in no significant change in the shape of silver particles before and after MM adsorption, silver particles, relatively strong It is considered to be aggregated. In contrast, if the supported silver HT-g-C ₃ N ₄ by the high shear treatment method of the embodiment, silver particles, the bonding force and cohesive force to the graphite-like carbon nitride is relatively weak, with the MM adsorptive binding It is inferred that the force and the cohesion decrease further and it changes to flat form (primary particles move like flat form) and the proportion of the surface increases, resulting in increase of adsorption capacity and improvement of photocatalyst removal rate. .

FIG. 6 shows the relationship between the silver loading amount, the adsorption capacity, and the photocatalyst removal rate. In the photo electrodeposition method of the comparative example, although the rate of removal of the photocatalyst shows a value of about 70% in the range of about 5% by weight or more of single silver support, the adsorption capacity remains at a low value. On the other hand, the high shear processing method according to the embodiment of the present invention shows a high photocatalyst removal rate of about 80% or more when the silver loading amount is in the range of 10 to 30% by weight and It shows an adsorption capacity of about 2 to 4 times.
Silver is also known to have adsorption and photocatalytic effects on sulfur compounds other than MM (eg hydrogen sulfide), and if MM is effective, other sulfur compounds (eg hydrogen sulfide) It is naturally expected that there will be an effect.

  By applying the metal-supported graphitic carbon nitride of the present invention to any substrate, it has a high adsorption performance to an offensive odor substance, and further has a photocatalytic action that suppresses oxidation when it is irradiated with visible light. It can be used as materials, indoor and outdoor building materials (wallpaper, blinds, curtains, glass, paint, etc.). In addition, if it is used in a deodorizing device or an air purification device, the deodorizing function can be expressed using an inexpensive visible light LED light source, and a high adsorption capacity causes an offensive odor substance without continuously irradiating light. It can be adsorbed.

Claims (9)

  A method for producing metal-complexed graphitic carbon nitride, characterized in that the powder of graphitic carbon nitride is subjected to high shear processing at a stirring peripheral speed of 2 m / s or more in a solution containing metal ions.   The method for producing metal-complexed graphitic carbon nitride according to claim 1, wherein the powder of graphitic carbon nitride has been previously hydrothermally treated in an aqueous alkali solution or an aqueous acid solution.   The method according to claim 1 or 2, wherein the metal of the metal ion is one or more selected from silver, gold and copper.   The method for producing metal-complexed graphitic carbon nitride according to any one of claims 1 to 3, wherein the metal is 10% or more by weight ratio to metal-complexed graphitic carbon nitride.   The method for producing metal-complexed graphitic carbon nitride according to any one of claims 1 to 4, wherein the solution containing a metal ion is a solution containing a metal inorganic salt, a metal organic salt or a metal organic complex.   A metal complexed graphitic carbon nitride in which one or more metals selected from silver, gold and copper are complexed to graphitic carbon nitride, and the amount of the metal supported is 10% by weight or more, and A metal-complexed graphitic carbon nitride, characterized in that the metal is movably complexed upon adsorption of methyl mercaptan. A metal complexed graphitic carbon nitride in which silver is complexed to graphitic carbon nitride, the supported amount of the silver is 10% by weight or more, and the specific surface area of the silver is 500 m ² / g or more A metal complexed graphitic carbon nitride characterized in that   A deodorant comprising metal composited graphitic carbon nitride according to claim 6 or 7, which has both adsorption performance and photocatalytic performance. A deodorizing apparatus comprising the deodorizing agent according to claim 8.

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