JP2017100923A - Metal composite carbon nitride for deodorization and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a novel production method which enables production of metal composite graphite-like carbon nitride having various metal supported highly dispersed thereon by a low-cost and simple method; and metal composite graphite-like carbon nitride which has a large adsorption capacity for odorous substances such as sulfur compounds and responds to visible light to show photocatalysis.SOLUTION: Provided is metal-supported graphite-like carbon nitride, comprising as a main component powder obtained by subjecting powder of graphite-like carbon nitride to a high shear treatment in an aqueous solution containing metal ions (gold, silver, copper, and the like). The obtained powder has a large adsorption capacity for odorous substances due to metal supported highly dispersed thereon and, at the same time, shows excellent photocatalytic activity not only under UV irradiation but also under visible light irradiation.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a novel method for producing metal-composited graphite-like carbon nitride carrying a metal, a novel metal-complexed graphite-like carbon nitride excellent in malodorous material adsorption performance and photocatalytic function, and the novel metal-composite The present invention relates to a deodorizing agent and a deodorizing apparatus using graphite-like carbon nitride.

As one of the deodorizing techniques that oxidize and degrade malodorous substances present in the living environment, there is a method using titanium oxide as a photocatalyst, but titanium oxide works only when exposed to ultraviolet light. Visible light contained in a large amount of light could not be used.
In recent years, a method using tungsten oxide that responds to visible light as a photocatalyst has also been developed. However, tungsten is more expensive than titanium oxide (about 10 times), and it is a strategic substance, so the supply is unstable. There's a problem.

Graphite-like carbon nitride (g-C ₃ N ₄ ) can be easily synthesized by thermally decomposing melamine or cyanamide, and has recently been known to act as a photocatalyst that responds to visible light (Non-Patent Documents). 1, 2). Graphite-like carbon nitride is advantageous in that it is cheaper than tungsten oxide and the supply is stable.

  However, even if graphite-like carbon nitride synthesized by the thermal decomposition of melamine or cyanamide is used as it is, the photocatalytic performance is low and it is far from practical use for air purification and deodorization. Therefore, various methods for improving the performance have been studied, a method for increasing the specific surface area by hydrothermal treatment to improve the air purification performance (Patent Document 1, etc.), and a method for encapsulating a metal between layers of graphite-like carbon nitride ( Patent Documents 2 and 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 for sulfur compounds such as methyl mercaptan, which are important as malodorous substances, are still low, and improvement is necessary.

  As a method for improving the adsorption performance of a catalyst or adsorbent for a sulfur compound, there is a method of supporting a metal such as silver by an impregnation method or a photo-deposition method. In the case where silver is supported, it is known that the adsorption performance is improved by supporting silver even in graphitic carbon nitride. The impregnation method cannot support a large amount of metal, while the photo-deposition method can support a relatively large amount of metal. However, when the amount of silver is increased, the adsorption amount per unit weight of silver is rather decreased, and silver is effective. Could not be used.

JP 2011-195212 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 and five others "Photocatalytic activity of carbon nitride (C3N4) under visible light irradiation" Catalyst debate A discussion paper Vol.102nd, Page.126 (2008.09.23)

The present invention has been made against the background of the prior art as described above, and is a relatively low-cost and simple process for producing a metal composite graphite-like carbon nitride that can be expected to have various functions and properties depending on the metal to be supported. It is an object of the present invention to provide a novel manufacturing method that can be manufactured by the manufacturing method.
The present invention also provides a novel production method capable of producing metal-composite graphite-like carbon nitride having a deodorizing performance and / or a photocatalytic function of malodorous substances such as sulfur compounds at a relatively low cost and a simple process. Is an additional issue.
In addition, the present invention provides a metal-composite graphite-like carbon nitride having excellent properties for adsorbing malodorous substances such as sulfur compounds, and oxidizing and degrading malodorous substances by irradiation with visible light and ultraviolet rays. It is an additional problem 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 composite graphite-like carbon nitride having a deodorizing performance of malodorous substances such as sulfur compounds and / or a photocatalytic function.
Another object of the present invention is to provide a novel metal composite graphite-like carbon nitride that has excellent adsorption performance for malodorous substances such as sulfur compounds and has the property of oxidizing and degrading malodorous substances by irradiation with visible light or ultraviolet light. And

Under the above-mentioned problems, the following findings were obtained in the course of various test studies.
(1) Manufactures a metal composite carbon nitride carrying a metal in a relatively low-cost simple process in which graphite-like carbon nitride is subjected to a high shear treatment at a predetermined stirring peripheral speed or higher in a solution containing metal ions. be able to.
(2) In the above production, by adjusting the kind and amount of the metal, it is possible to obtain a metal composite carbon nitride having a high adsorption ability against malodorous substances such as sulfur compounds and a high photocatalytic removal rate.
(3) Graphite-like carbon nitride (hereinafter referred to as “g-C ₃ N ₄ ”) prepared by pyrolyzing a nitrogen-containing organic compound such as melamine or cyanamide is preliminarily placed in an alkaline aqueous solution such as sodium hydroxide or When the specific surface area of g-C ₃ N ₄ is increased by 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 raw materials for metal ions. However, when silver acetate is used, the highest adsorption performance can be obtained. Even when silver at a weight ratio of about 24% is added, the adsorption performance per atom of silver is higher than in the conventional method at a weight ratio of 1%.
(5) In the case of a product produced by a conventional photo-deposition method, the supported metal particles are considered not to move on the surface of the graphite-like carbon nitride before and after the adsorption of malodorous substances such as sulfur compounds. In those produced by shearing treatment, the supported metal particles have a relatively weak cohesive force and a relatively weak binding force to graphitic carbon nitride, and the binding force and cohesive force are further increased with the adsorption of malodorous substances such as sulfur compounds. It is considered that the ratio decreases to a flat plate shape and the surface ratio increases. As a result, in the one manufactured by the high shear treatment of the present invention, the adsorption capacity and photocatalyst removal rate of malodorous substances such as sulfur compounds are larger than those by the photo-deposition method by setting the kind and amount of the metal to be supported. It can be improved and an adsorbent excellent in malodorous substances can be obtained.

The present invention has been completed based on the findings as described above, and according to the present invention, the following inventions are provided.
<1> A method for producing metal-complexed graphite-like carbon nitride, comprising subjecting graphite-like carbon nitride powder to a high shearing treatment with a stirring peripheral speed of 2 m / s or more in a solution containing metal ions.
<2> The method for producing metal-complexed graphite-like carbon nitride according to <1>, wherein the graphite-like carbon nitride powder is hydrothermally treated in advance in an alkaline aqueous solution or an acidic aqueous solution.
<3> The method for producing metal-complexed graphite-like carbon nitride according to <1> or <2>, wherein the metal ions are one or more selected from silver, gold, and copper.
<4> The method for producing a metal composite graphite-like carbon nitride according to any one of <1> to <3>, wherein the metal is 10% or more by weight with respect to the metal composite graphite carbon nitride. .
<5> The metal-complexed graphite-like carbon nitride according to any one of <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. Manufacturing method.
<6> Metal composite graphite-like carbon nitride in which one or more kinds of metals selected from silver, gold, and copper are combined with graphite-like carbon nitride, and the supported amount of the metal is 10% by weight or more. And a metal-complexed graphite-like carbon nitride, wherein the metal is compounded so as to be movable during the adsorption of methyl mercaptan.
<7> Metal composite graphite-like carbon nitride in which silver is composited with graphite-like carbon nitride, the supported amount of silver is 10% by weight or more, and the specific surface area of the silver is 500 m ² / g. Metal composite graphite-like carbon nitride characterized by the above.
<8> A deodorant having both adsorption performance and photocatalytic performance, and comprising the metal-composited graphite-like carbon nitride according to <6> or <7> as an active ingredient.
<9> A deodorizing apparatus comprising the deodorizing agent according to <8>.

The present invention can include the following aspects.
<10> The method for producing a metal-complexed graphite-like carbon nitride according to any one of <1> to <5>, wherein the stirring peripheral speed is 2.5 to 12 m / s.
<11> The metal composite graphite-like nitride according to any one of <1> to <5>, <10>, wherein the metal is 10 to 35% by weight with respect to the metal composite graphite-like carbon nitride. Carbon manufacturing method.
<12> The metal composite according to any one of <1> to <5>, <10>, <11>, wherein the graphite-like carbon nitride powder to be mixed is synthesized by thermal decomposition of melamine or cyanamide. Method for producing graphitic carbon nitride.
<13> The metal composite graphite-like carbon nitride according to <6> or <7>, wherein the metal loading is 11 to 33% by weight.
<14> The metal composite graphite-like carbon nitride according to <6>, <7> or <13>, wherein the adsorption capacity of methyl mercaptan is 300 μmol / g or more.
<15> A deodorizer having both adsorption performance and photocatalytic performance, and comprising the metal-composited graphite-like carbon nitride according to <13> or <14> as an active ingredient.
<16> A deodorizing apparatus comprising the deodorizing agent according to <15>.

According to the production method of the present invention, it is possible to produce a metal composite graphite-like carbon nitride that can be expected to have various functions and properties depending on the metal to be supported by a relatively low cost and simple process.
Further, according to the production method of the present invention, the metal composite graphite-like carbon nitride having a deodorizing performance of a bad odor substance such as a sulfur compound and a photocatalytic function can be relatively reduced by appropriately setting the type and amount of the metal. It can be manufactured by a cost and simple process.
The deodorizing carbon nitride of the present invention is an adsorbent excellent in malodor substance adsorption performance, and has a property of oxidizing and degrading malodorous substances by irradiation with visible light or ultraviolet rays.

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. An electron micrograph of graphitic carbon nitride carrying Ag by high shear treatment. (a) shows before methyl mercaptan (MM) adsorption, and (b) shows after MM adsorption. The figure which shows the change of the peak of silver (Ag3d) of the X-ray photoelectron spectroscopy by methyl mercaptan (MM) adsorption | suction of Ag carrying | support graphite-like carbon nitride, or visible light irradiation. (a) shows before MM adsorption, (b) after MM adsorption, and (c) after visible light irradiation following MM adsorption. The schematic diagram which shows the apparatus which analyzes the deodorizing performance used in the Example of this invention. The figure which shows the profile of the photocatalytic decomposition | disassembly by the adsorption | suction of methyl mercaptan by graphite-like carbon nitride which carry | supported silver by the high shear process, and irradiation of visible light. The figure which showed the silver carrying amount dependence of the adsorption capacity and photocatalyst removal rate of Ag carrying | support graphite-like carbon nitride. □ shows the results obtained by the high shear treatment method of the example of the present invention, and ○ shows the results obtained by the photo-deposition method of the comparative example.

The method for producing metal-complexed graphite-like carbon nitride of the present invention is characterized by subjecting graphite-like carbon nitride powder to a 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 production method of the present invention, a metal composite graphite-like carbon nitride having a relatively large amount of supported metal compared to the conventional impregnation method can be produced by a simple process with a relatively low cost compared to the conventional photo-deposition method. Can do.
By carrying out high shear treatment of graphitic carbon nitride in a solution containing metal ions, in the case of easily reduced metal ions, at least a part of the metal ions is reduced and deposited, and dispersed and supported on the graphite carbon nitride Is done. Further, in the case of metal ions that are difficult to reduce, a part of the metal ions are precipitated and dispersed and supported on the graphitic carbon nitride. It is assumed that the produced metal composite graphite-like carbon nitride exhibits various functions and properties that cannot be obtained only by graphite-like carbon nitride, depending on the metal to be supported.

  The graphite-like carbon nitride powder used for the production is not limited, and examples thereof include those synthesized by pyrolyzing melamine, cyanamide, dicyandiamide, urea, triazine, triazine chloride, cyanuric acid, or a mixture thereof. . Although the powder to be used is not limited, the average particle diameter is usually about 1 to 30 μm.

  The graphite-like carbon nitride powder is desirably hydrothermally treated in advance in an alkaline aqueous solution or an acidic aqueous solution so as to increase the specific surface area. The alkaline hydrothermal treatment is carried out by adding graphite-like carbon nitride in an aqueous solution containing sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and the like having a concentration of 0.05 to 0.2 mol / l and stirring at 70 to 150 ° C. It can carry out by heating to. The acid hydrothermal treatment is performed by placing graphite-like carbon nitride in an aqueous solution containing hydrochloric acid, nitric acid, sulfuric acid or the like having a concentration of 0.05 to 0.2 mol / l and heating to 130 to 170 ° C. with stirring. it can.

Examples of the metal supported on the graphite-like carbon nitride include, but are not limited to, silver, gold, copper, platinum, palladium, nickel, iridium, rhodium, osmium, ruthenium, iron, cobalt, manganese, molybdenum, and zinc. Can be mentioned.
In the case of expecting a photocatalytic function to metal composite graphite-like carbon nitride, but not limited to, silver, gold, copper, platinum, palladium, nickel, iridium, rhodium, osmium, ruthenium, iron, cobalt, etc. It is done.
In the case of expecting both the photocatalytic function and the adsorption performance for sulfur compounds etc. to the metal composite graphite-like carbon nitride, silver, gold, copper, nickel and the like can be mentioned, preferably silver, gold, particularly silver. preferable.

  The amount of the metal supported on the metal composite graphite carbon nitride is not limited, but is determined according to the degree of the obtained function and property. Usually, the amount is 5% by weight or more, preferably 10% by weight or more, and more preferably 12% by weight or more in a larger amount 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, more preferably 30% by weight or less.

In the present invention, the high shear treatment means mixing by stirring at 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.
A stirrer used for the high shear treatment is not limited, and a commercially available homogenizer, mixer, blender, or the like can be used.
In addition, since a general magnetic stirrer is normally used at about 100 to 500 revolutions / minute, when the length of the stirring bar is 25 mm and 500 revolutions / 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. Examples of the metal inorganic acid salt include, but are not limited to, nitrates, sulfates, hydrochloride carbonates, phosphates, and the like. Preferred are nitrates and hydrochlorides, and more preferred are nitrates. 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, and hydrocomplex.

  The temperature of the solution used for the high shear treatment is not limited, but can be room temperature. During the high shearing process, the temperature of the solution rises to, for example, about 70 ° C., but the metal can be supported even after cooling.

The metal composite graphite-like carbon nitride of the present invention produced by the high shear treatment as described above has a metal content ratio as compared with the metal composite graphite-like carbon nitride produced by the stirring treatment with a conventional magnetic stirrer. Can do a lot.
When the metal composite graphite-like carbon nitride of the present invention is compared with the metal composite graphite-like carbon nitride produced by the conventional photo-deposition method, there is not much difference in terms of the amount of supported metal, but the graphite nitride It is considered that the metal loading state in carbon is greatly different. In the one produced by the conventional photo-deposition method, the supported metal particles have a relatively strong cohesive force and are also relatively strongly bonded to the graphite-like carbon nitride, so that the graphite-like particles are adsorbed before and after the adsorption of malodorous substances such as sulfur compounds. It is thought that it does not move on the carbon nitride surface. On the other hand, in the product produced by the high shear treatment of the present invention, the supported metal particles have a relatively weak cohesive force and a relatively weak binding force to graphite-like carbon nitride, accompanying adsorption of malodorous substances such as sulfur compounds. Thus, it is considered that the bonding force and cohesive force are further reduced to change into a tabular shape (primary particles move in a tabular shape), and the surface ratio increases. As a result, in the one manufactured by the high shear treatment of the present invention, the adsorption capacity and photocatalyst removal rate of malodorous substances such as sulfur compounds are larger than those by the photo-deposition method by setting the kind and amount of the metal to be supported. It can be improved and an adsorbent excellent in malodorous substances can be obtained.

  Hereinafter, although the present invention is explained based on an example etc., the present invention is not limited to this example.

(Reference Example 1: Production of graphitic carbon nitride powder)
Graphite-like 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 an alumina crucible, covered, baked in an electric furnace at 550 ° C. for 1 hour, the product is ground in a mortar, and then put again in the crucible for another hour 550 Baked at ℃. 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, and it was polyheptazine (C ₆ N ₉ H ₃ ) among substances generically called graphitic carbon nitride (g-C ₃ N ₄ ). X-ray diffraction results also showed polyheptadine. In addition, when cyanamide is used as a carbon nitride raw material, almost the same results are obtained, and therefore a carbon nitride raw material other than melamine may be used. The median value of g-C ₃ N ₄ pore size distribution obtained by adsorption of nitrogen molecules at liquid nitrogen temperature was in the vicinity of 30 to 50 nm.

(Reference Example 2: Alkaline hydrothermal treatment of g-C ₃ N ₄ )
The g-C ₃ N ₄ powder (1.0 g), sodium hydroxide (0.40 g), and water (90 ml) are placed in a Teflon (registered trademark) crucible and stirred. The sodium hydroxide concentration at this time is 0.11 mol / l. A 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 (registered trademark) 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 centrifugation (14500 G for 20 minutes) with an ultracentrifuge (Model Kubota Microcooled Centrifuge Model 3700). A heat treated graphitic carbon nitride (HT-g-C ₃ N ₄ ) was obtained. 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 HT-g-C ₃ N ₄ determined by adsorption of nitrogen molecules at liquid nitrogen temperature was in the vicinity of 3 to 8 nm.

<Production of metal composite graphite-like carbon nitride>
(Comparative Example 1: Metal loading by impregnation method in g-C ₃ N ₄ or HT-g-C ₃ N ₄ )
After mixing 0.40 g of the g-C ₃ N ₄ or HT-g-C ₃ N ₄ powder and 0.80 ml of an aqueous silver nitrate solution containing 0.040 g of silver, the water is removed at 100 ° C. After further mixing using an agate mortar, the mixture was put 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 with an agate mortar to obtain g-C ₃ N ₄ or HT-g-C ₃ N ₄ carrying silver.

(Comparative Example 2: Metal loading by photo-deposition method on g-C ₃ N ₄ or HT-g-C ₃ N ₄ )
Put 0.20 g of the above g-C ₃ N ₄ or HT-g-C ₃ N ₄ powder into a glass container having a quartz lid, and add 30 mL of silver nitrate aqueous solution containing 0.0000274 g to 0.0648 g of silver. Suspend. While passing nitrogen gas at a flow rate of 50 mL / min and stirring with a magnetic stirrer (stirring peripheral speed of about 0.5 m / s), an ultra-high pressure mercury lamp (Ushio, USH-500D, 500 W) was passed through a quartz lid. Light was irradiated for 30 minutes to deposit silver on the carbon nitride. The sample was washed three times with 30 mL of water and collected using a centrifuge (20 minutes at 14500 G) and finally dried at 80 ° C. overnight.

(Example 1: Metal loading by high shear treatment on g-C ₃ N ₄ or HT-g-C ₃ N ₄ )
Put 0.20 g of the above g-C ₃ N ₄ powder or HT-g-C ₃ N ₄ powder, 0.10 g of silver acetate and 10 ml of water into a glass test tube having a diameter of 20 mm, and use an ultrasonic generator. Then, silver acetate was dissolved. The silver ion concentration at this time is 0.06 mol / l. A rotary homogenizer (ADG-160D manufactured by ASONE) having a rotating 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, and is 10000 rotations / minute or 5000 rotations / minute. High shear treatment (Agitating peripheral speed = 0.013 (m) x π x 10000/60 (seconds) = 6.8 m / s or 0.013 (m) x π x 5000/60 (seconds) = 3.4 m / s) It was done for 70 minutes. Further, high shear treatment was performed in the same manner as described above except that the rotation speed was 15000 rpm (mining peripheral speed 10.2 m / s) and 10 minutes. The suspension in the test tube was centrifuged (20 minutes at 14500 G) with an ultracentrifuge (Microcooled Centrifuge Model 3700 manufactured by Kubota) to obtain a precipitate. Add 30 ml of water to the precipitate, stir, and centrifuge again to remove impurities from the precipitate to obtain silver-supported g-C ₃ N ₄ or HT-g-C ₃ N ₄ It was. Each is expressed as Ag / g-C ₃ N ₄ or Ag / HT-g-C ₃ N ₄ . In the case of using silver nitrate instead of silver acetate as the 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 g-C 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 to generate ultrasonic waves. The metal salt was dissolved using a vessel. Using a rotary homogenizer (ADG-160D manufactured by ASONE) having a head with a diameter of 18 mm, high shearing treatment (stirring peripheral speed = 6.8 m / s) rotating at 10000 rpm was performed for 40 minutes. The suspension in the test tube was centrifuged (20 minutes at 14500 G) with an ultracentrifuge (Microcooled Centrifuge Model 3700 manufactured by Kubota) to obtain a precipitate. 30 ml of water is added to the precipitate, stirred, and centrifuged again to remove impurities from the precipitate, and the target metal-supported g-C ₃ N ₄ or HT-g-C ₃ N ₄ Got.
The amount of the metal salt to be added was appropriately adjusted so that the supported metal was 1 to 22.4% by weight with respect to the metal composite graphite-like 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 FIG. 2 shows X-ray diffraction patterns of Ag / g—C ₃ N ₄ and Ag / HT-g—C ₃ N ₄ supporting silver by the method of Example 1 described in FIG. A main peak near 27.4 ° and an unclear diffraction from 12 to 25 ° can be confirmed. The average layer spacing of g-C ₃ N ₄ was calculated as about 3.3 mm from the position of the main peak, and it was confirmed that it was a conventionally known g-C ₃ N ₄ . The pattern of HT-g-C ₃ N ₄ subjected to alkaline hydrothermal treatment was not significantly different from that before hydrothermal treatment.
When a high shear treatment was performed in an aqueous solution of silver acetate, the intensity of the main peak at 27.4 ° decreased and diffraction at 12-25 ° could not be confirmed. The decrease in the peak observed here is due to the interaction between the silver ions and the graphite-like carbon nitride, and the layer spacing is no longer constant by 3.3 mm, and the diffraction is weakened by disturbing the periodic structure. There is no silver peak, suggesting that silver is highly dispersed.

FIG. 2 shows an electron micrograph of Ag / HT-g-C ₃ N ₄ obtained by high shear treatment. In spite of the addition of a large amount of silver, it was confirmed that the particles were supported on graphite-like carbon nitride as silver nanoparticles having a particle size [= (major axis + minor axis) / 2] of about 5 nm to 30 nm.

Ag / HT-g-C ₃ N ₄ obtained by high shearing treatment is analyzed by energy dispersive X-ray analysis of element distribution (not shown). As a result, silver reduced to the entire graphite-like carbon nitride Was confirmed to be supported. 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 composite carbon nitride>
FIG. 4 is a diagram showing an apparatus for analyzing deodorizing performance, and is based on a measuring apparatus described in JIS R1751-1 used for measuring the decomposition performance of malodorous substances by a photocatalyst. Using this apparatus, the deodorizing performance was measured as follows in accordance with JIS R1751-5.

A photocatalyst test is performed by suspending 0.10 g of the graphitic carbon nitride sample supporting the metal in about 1 ml of water, applying the entire amount to a glass plate having a width of 50 mm and a length of 100 mm, and drying at 50 ° C. Pieces were prepared. The test piece is placed in the photocatalytic reaction vessel shown in FIG. 4, covered with a cover made of borosilicate glass, and covered so that the photocatalyst is not exposed to light.
A simulated contaminated air containing 5 ppm methyl mercaptan and having a relative humidity of 50% (25 ° C.) is prepared by a mass flow controller and is circulated through the bypass at a flow rate of 0.50 L / min. The concentration of methyl mercaptan (MM) in the simulated contaminated air is measured with a gas chromatograph (Shimadzu GC-14B) equipped with a flame ionization detector (FID). After the methyl mercaptan concentration, humidity, and flow rate are stabilized, simulated polluted air is circulated through the photocatalytic reaction vessel by switching the valve. MM and dimethyl disulfide (DMDS) emerging from the reaction vessel are measured with a gas chromatograph. When the sample piece adsorbs MM, the MM concentration decreases. Thereafter, as the MM covers the silver surface, the adsorption rate decreases, and the concentration gradually increases. The amount adsorbed before exceeding 4.5 ppm is obtained by calculation and is defined as the MM adsorption amount. Further, the adsorption amount per 1 g of the sample powder is defined as the adsorption capacity.
After the amount of increase in MM concentration decreases, the sample is irradiated with light to initiate the photocatalytic reaction. A white fluorescent lamp (Toshiba FL10W) was used as the light source, the illuminance was 6000 Lx, and ultraviolet rays contained in the fluorescent lamp light were removed using an ultraviolet light removal filter (N-169, manufactured by Nitto Resin Co., Ltd.). [MM concentration at bypass]-[MM concentration at outlet of reaction vessel when irradiated with light]} / {[MM concentration at bypass]} × 100 was defined as the MM removal rate.

FIG. 5 shows the results of a deodorization performance evaluation test using Ag / HT-g-C ₃ N ₄ . When simulated contaminated air was brought into contact with the sample, the MM concentration decreased rapidly to 0.2 ppm. After several hours, the MM concentration began 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 MM can be removed by visible light. Even after 100 hours had passed since irradiation with light, 50% or more of MM was removed.

Table 1 shows the results of deodorization tests with metal-supported graphite-like carbon nitride loaded with metal and unsupported graphite-like carbon nitride. Preparation method (metal precipitation method), loading amount [of metal relative to metal-complexed graphite-like carbon nitride Supported amount (% by weight)], specific surface area [specific surface area of metal composite carbon nitride (m ² / g)], adsorption capacity (μmol / g), metal specific surface area (m ² / g), photocatalyst removal rate [light Average MM removal rate (%) until 3 hours after irradiation] was shown.
The specific surface area of graphite-like carbon nitride or metal-complexed graphite-like carbon nitride was measured by a multipoint BET method using nitrogen as an adsorbate. Belsorp-Max manufactured by Nippon Bell was used for the measurement. About 0.1 g of a sample was placed in a sample holder, degassed at 120 ° C. for 3 hours, and then the specific surface area was measured.
The specific surface area of the metal is (1) all the metal particles supported on the graphite-like carbon nitride are spheres of the same diameter, and (2) the MM of the adsorption capacity measured on the entire surface of the supported metal particles is adsorbed. (3) Assuming that the adsorption area of MM1 molecule is 22.4 mm (0.224 nm ² ) (see Miyoshi Ho ^{2 and} Occupational Medicine 19 2-7 (1977) table 4.). Based on the calculation.

As is apparent from Table 1, it was found that the graphite-like 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 was used as a precursor and silver was supported by the conventional impregnation method or photo-deposition method, the adsorption capacity and the photocatalytic removal rate increased. When 1% by weight of silver was supported on HT-g-C ₃ N ₄ by the photodeposition method, an adsorption capacity of 21 μmol / g and a photocatalyst removal rate of 49% were obtained.
When the supported amount of silver was increased to 24.4%, the adsorption capacity increased to 340 μmol / g, but the adsorption amount per unit weight of silver decreased. Moreover, the metal specific surface area important for adsorption was also reduced.
When silver was supported at a weight ratio of 24.4% by the high shearing method, an adsorption capacity three times or more that of the photo-deposition method was obtained. Even in the same high shear treatment method, when silver acetate was used as a precursor, an adsorption capacity 1.5 times that of silver nitrate and a photocatalyst removal rate higher than 10% were obtained. The average number of MM molecules that can be adsorbed per silver atom was 0.59 in the high shear treatment method and 0.14 in the photodeposition method. It was found that silver particles advantageous for MM adsorption can be formed by using a high shear treatment method.
Even when g-C ₃ N ₄ not subjected to alkaline hydrothermal treatment was used, a high adsorption capacity of 691 μmol / g was exhibited when 24.4% of silver was supported by the high shear treatment method. It was also confirmed that the specific surface area was increased by the high shear treatment. Even if the alkaline hydrothermal treatment was not previously applied to the graphitic carbon nitride, better results were obtained than the conventional silver loading method. 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 treatment method, and a significantly higher adsorption capacity and photocatalyst removal rate were obtained than when no metal was added or when copper was supported by the photodeposition method. There was no effect on iron loading.
When a similar test was carried out with 24.4% silver supported on titanium oxide, which has been conventionally known as a photocatalyst, an adsorption capacity of 79 μmol / g and a photocatalyst removal rate of 55% were obtained. Both values were significantly lower than those of graphite-like carbon nitride carrying silver by a high shear treatment method.

FIG. 2B shows an electron micrograph after MM adsorption of the silver-supported HT-g-C ₃ N ₄ of the example. From the spherical shape or hemispherical shape before MM adsorption, or from a shape close to them, a band shape is observed.
It shows the change in peak of the silver-bearing HT-g-C ₃ N ₄ of MM adsorption and X-ray photoelectron spectroscopy using visible light irradiation silver (Ag3d) in FIG. The peak of silver (Ag3d) is large after MM adsorption, and it is assumed that the aggregate has a small surface ratio before MM adsorption and has changed to a flat plate shape with a large surface ratio.
In the case of the silver-supported HT-g-C ₃ N ₄ by the photo-deposition method of the comparative example, the silver particles are relatively strong because there is no significant change in the shape of the silver particles before and after MM adsorption (not shown). It is thought that it aggregated. On the other hand, in the case of silver-supported HT-g-C ₃ N ₄ by the high shear treatment method of the embodiment, the silver particles have relatively weak binding force and cohesive force with respect to the graphite-like carbon nitride, and are bonded with MM adsorption. It is presumed that the force and cohesive force further decreased to change into a flat plate shape (primary particles moved into a flat plate shape), and the surface ratio increased, resulting in an increased adsorption capacity and an improved photocatalyst removal rate. .

FIG. 6 shows the relationship between the amount of supported silver, the adsorption capacity, and the photocatalyst removal rate. In the comparative example based on the photo-deposition method, although the photocatalyst removal rate shows a value of about 70% in a range where the silver self-supporting is about 5% by weight or more, the adsorption capacity remains low. On the other hand, the high shear treatment method of the embodiment of the present invention shows a high photocatalyst removal rate of about 80% or more in the range of 10 to 30% by weight of the silver supported, and compared with the photodeposition method. The adsorption capacity is about 2 to 4 times.
Silver is also known to have adsorption and photocatalytic effects on sulfur compounds other than MM (eg, hydrogen sulfide). If it is effective on MM, other sulfur compounds (eg, hydrogen sulfide) Is naturally expected to be effective.

  By applying the metal-supported graphite-like carbon nitride of the present invention to any substrate, it has high adsorption performance against malodorous substances, and also has photocatalytic action that oxidizes and suppresses odor when exposed to visible light It can be used as materials, indoor / outdoor building materials (wallpaper, blinds, curtains, glass, paint, etc.). Moreover, if it is used in a deodorizing device or an air purifying device, a deodorizing function can be expressed using an inexpensive visible light LED light source, and a malodorous substance can be produced with a high adsorption capacity even without continuous light irradiation. Can be adsorbed.

Claims (9)

  A method for producing a metal-complexed graphite-like carbon nitride, comprising subjecting graphite-like carbon nitride powder to a high shear treatment with a stirring peripheral speed of 2 m / s or more in a solution containing metal ions.   The method for producing metal-complexed graphite-like carbon nitride according to claim 1, wherein the graphite-like carbon nitride powder is previously hydrothermally treated in an alkaline aqueous solution or an acid aqueous solution.   The method for producing metal-complexed graphite-like carbon nitride according to claim 1 or 2, wherein the metal of the metal ion is one or more selected from silver, gold, and copper.   The said metal is 10% or more by weight ratio with respect to metal composite graphite-like carbon nitride, The manufacturing method of metal composite graphite-like carbon nitride of any one of Claims 1-3.   The method for producing metal-complexed graphite-like carbon nitride according to any one of claims 1 to 4, wherein the solution containing metal ions is a solution containing a metal inorganic salt, a metal organic salt, or a metal organic complex.   One or more kinds of metals selected from silver, gold, and copper are metal composite graphite-like carbon nitride obtained by compounding graphite-like carbon nitride, and the amount of the metal supported is 10% by weight or more, and The metal-complexed graphite-like carbon nitride, wherein the metal is compounded so as to be movable during the adsorption of methyl mercaptan. Metal composite graphite-like carbon nitride in which silver is compounded with graphite-like carbon nitride, the supported amount of silver is 10% by weight or more, and the specific surface area of the silver is 500 m ² / g or more A metal composite graphite-like carbon nitride characterized by the above.   A deodorizer having both adsorption performance and photocatalytic performance and comprising the metal-complexed graphite-like carbon nitride according to claim 6 or 7 as an active ingredient. A deodorizing apparatus comprising the deodorizer according to claim 8.

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