JP7275343B1 - Impregnated activated carbon, manufacturing method thereof, and manufacturing equipment for impregnated activated carbon - Google Patents

Abstract

An object of the present invention is to provide a method for producing impregnated activated carbon having sufficiently excellent mercury (Hg0) adsorption performance. The method includes a step of impregnating the activated carbon 10 with the halogen compound 20 by spraying an aqueous solution of a diatomic halogen compound 20 onto the activated carbon 10 obtained by activating the carbon material, wherein the carbon material is coal. and the carbon content of the activated carbon 10 is 70% by mass or more. [Selection drawing] Fig. 1

Description

The present disclosure relates to impregnated activated carbon, a method for producing the same, and an impregnated activated carbon production facility.

Exhaust gases generated by various facilities may contain harmful components such as mercury and dioxins. Activated carbon is used as an adsorbent for such harmful components. Since normal activated carbon can hardly adsorb mercury (Hg ⁰ ) at high temperatures exceeding 100° C., it is necessary to use impregnated activated carbon. As the impregnated activated carbon, those impregnated with a halogen compound, a metal compound, sulfur, or the like are known (see, for example, Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2002-102653 JP 2020-199425 A

In order to increase the adsorption power of mercury (Hg ⁰ ), various compounds have been studied as compounds to be impregnated with activated carbon. The present disclosure provides an impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance and a method for producing the same. Further, the present invention provides production equipment for impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance.

In one aspect, the present disclosure has a step of impregnating the activated carbon with the halogen compound by spraying an aqueous solution of a diatomic halogen compound onto the activated carbon obtained by activating the carbon material, wherein the carbon material is Provided is a method for producing impregnated activated carbon, which contains coal and has a carbon content of 70% by mass or more.

In the above production method, a diatomic halogen compound is used as the compound to be impregnated on the activated carbon. Since such a diatomic halogen compound has a small molecular size, it easily penetrates into the micropores of the activated carbon. Here, since the activated carbon is derived from coal and has a high carbon content, it has sufficiently small micropores (pore diameter: 1 nm or less). Therefore, harmful substances other than mercury (Hg ⁰ ) can be sufficiently adsorbed. Moreover, the activated carbon has not only sufficiently small micropores but also large micropores (pore diameter: 1 to 2 nm). Therefore, the halogen compound in the aqueous solution smoothly enters through the larger micropores and is retained inside the activated carbon particles. If the halogen element is retained on the surface of the activated carbon particles, the London dispersion force (induced dipole action) cannot be sufficiently exerted. However, in the above production method, the halogen element is retained inside the activated carbon. Therefore, the London dispersing power of the halogen element can be sufficiently exhibited. Therefore, the adsorption performance of mercury (Hg ⁰ ) obtained by the above production method is sufficiently excellent.

In the above manufacturing method, the carbon content of the carbonaceous material may be 70% by mass or more. Such a carbonaceous material moderately has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm). Therefore, the impregnated activated carbon obtained using such a carbonaceous material can have both adsorption performance for harmful substances other than mercury (Hg ⁰ ) and adsorption performance for mercury (Hg ⁰ ) at sufficiently high levels. .

In the above production method, the carbonaceous material may contain at least one selected from the group consisting of bituminous coal and anthracite coal. Such a carbonaceous material moderately has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm). Therefore, the impregnated activated carbon obtained using such a carbonaceous material can have both adsorption performance for harmful substances other than mercury (Hg ⁰ ) and adsorption performance for mercury (Hg ⁰ ) at sufficiently high levels. .

In the above production method, the ratio of the halogen compound attached to the activated carbon may be 1.5 to 5% by mass. Such impregnated activated carbon has even better adsorption performance for mercury (Hg ⁰ ).

The specific surface area of the impregnated activated carbon produced by the above production method may be 600 to 1100 m ² /g. Such impregnated activated carbon is also sufficiently excellent in adsorption performance for harmful substances other than mercury (Hg ⁰ ).

A is the integrated value of the differential pore volume [dVp/d (dp)] with a pore diameter of 1 nm or less in the activated carbon of the above production method; dp)], the following equations (1) and (2) may be satisfied.
A≧3 cm ³ /g/nm (1)
B/A≧0.2 (2)

Such activated carbon has sufficiently small micropores (pore size: 1 nm or less) and large micropores (pore size: 1 to 2 nm) in a sufficiently good balance. Therefore, the adsorption performance of harmful substances other than mercury (Hg ⁰ ) can be maintained at a sufficiently high level, and the London dispersing power of the halogen element is sufficiently exhibited, and the adsorption performance of mercury (Hg ⁰ ) is sufficiently increased. be able to.

The concentration of the halogen compound in the aqueous solution may be 40-120 g/100 mL. Since such an aqueous solution has an appropriate concentration, the halogen compound in the aqueous solution can be appropriately dispersed and impregnated inside the micropores of the activated carbon. Therefore, impregnated activated carbon having sufficiently high mercury (Hg ⁰ ) adsorption performance can be stably produced.

The halogen compound may contain sodium bromide, and the concentration of sodium bromide in the aqueous solution may be 30 to 42% by mass. Such an aqueous solution can stably dissolve sodium bromide without precipitation even at room temperature. By using such an aqueous solution, bromine can be appropriately dispersed and impregnated inside the micropores of the activated carbon. Such impregnated activated carbon has higher mercury (Hg ⁰ ) adsorption performance.

In the above production method, a stirring device for stirring activated carbon and a nozzle for spraying the aqueous solution may be used, and the aqueous solution may be sprayed from the nozzle onto the activated carbon while stirring the activated carbon with the stirring device to obtain the impregnated activated carbon. Thereby, the halogen compound is impregnated on the activated carbon with high uniformity. Therefore, impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance can be easily mass-produced.

In one aspect, the present disclosure includes activated carbon and sodium bromide impregnated on the activated carbon, the activated carbon is a product of activated coal with a carbon content of 70% by mass or more, and has an odor An impregnated activated carbon having a sodium chloride ratio of 1.5 to 5% by mass is provided.

Such impregnated activated carbon includes activated carbon that is a product of activated coal and has a carbon content of 70% by mass or more. Such activated carbon moderately has both sufficiently small micropores (pore size: 1 nm or less) and large micropores (pore size: 1 to 2 nm). Therefore, it is possible to maintain the adsorption performance of harmful substances other than mercury (Hg ⁰ ). In addition, bromine can be stably retained inside the activated carbon. Therefore, the London dispersion force is sufficiently exerted, and the adsorption performance of mercury (Hg ⁰ ) can be sufficiently enhanced.

In one aspect, the present disclosure provides a stirring device for stirring a sediment layer of coal-derived activated carbon, an introduction unit for introducing activated carbon having a carbon content of 70% by mass or more into the stirring device, and deposition from above the sediment layer. Provided is an impregnated activated carbon production facility comprising: a nozzle for spraying an aqueous solution of a diatomic halogen compound toward a layer;

In the above manufacturing facility, activated carbon derived from coal and having a carbon content of 70% by mass or more and a diatomic halogen compound are used. Since the diatomic halogen compound has a small molecular size, it easily penetrates into the micropores of the activated carbon. Since activated carbon is derived from coal and has a high carbon content, it has sufficiently small micropores (pore diameter: 1 nm or less). Therefore, harmful substances other than mercury (Hg ⁰ ) can be sufficiently adsorbed. Moreover, the activated carbon has not only sufficiently small micropores but also large micropores (pore diameter: 1 to 2 nm). Therefore, the halogen compound in the aqueous solution sprayed from the nozzle smoothly penetrates through the larger micropores and is retained inside the activated carbon particles. If the halogen element is retained on the surface of the activated carbon particles, the London dispersion force (induced dipole action) cannot be sufficiently exerted. derived. Such impregnated activated carbon can sufficiently exhibit the London dispersing power of the halogen element. Therefore, the production facility described above can produce impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance.

The aqueous solution is sprayed from the nozzle so that the ratio of the sprayed area of the aqueous solution from the nozzle to the total area of the surface of the deposited layer is 40 to 120% when viewed from the top of the deposited layer in the stirring device. you can Thereby, the halogen compound can be impregnated on the activated carbon with high uniformity.

It is possible to provide an impregnated activated carbon having sufficiently excellent adsorption performance for mercury (Hg ⁰ ) and a method for producing the same. It is possible to provide production equipment for impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance.

FIG. 4 is a diagram schematically showing an example of a cross section near the surface of impregnated activated carbon. It is a figure which shows an example of the manufacturing apparatus used for the manufacturing method of impregnated activated carbon. (A) is a side view of the device, and (B) is a top view of the interior cut along line IIb-IIb of (A). 1 is a diagram showing the results of component analysis of activated carbon of Example 1. FIG. 3 is a diagram showing the result of component analysis of impregnated activated carbon of Comparative Example 1. FIG. 1 is a diagram showing distributions of differential pore volumes [dVp/d(dp)] of activated carbons used in Example 1 and Comparative Examples 1 and 2. FIG. FIG. 10 is a diagram showing a manufacturing apparatus used in Example 10; (A) is a side view of the device, and (B) is a top view of the inside of the device cut along line VIb-VIb in (A). FIG. 11 is a diagram showing a manufacturing apparatus used in Example 11; (A) is a side view of the device, and (B) is a top view of the interior of the device cut along line VIIb-VIIb of (A). FIG. 12 is a diagram showing a manufacturing apparatus used in Example 12; (A) is a side view of the device, and (B) is a top view of the interior of the device cut along line VIIIb-VIIIb of (A). (A) and (B) are diagrams schematically showing cross sections in the vicinity of the surface of impregnated activated carbon of a comparative example.

An embodiment of the present disclosure will be described below with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and overlapping descriptions are omitted in some cases. In addition, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratio of each element is not limited to the illustrated ratio.

A method for producing impregnated activated carbon according to one embodiment includes a step of impregnating activated carbon with a halogen compound by spraying an aqueous solution of a diatomic halogen compound onto activated carbon obtained by activating a carbonaceous material.

The carbon content of the carbon material measured by component analysis may be 70% by mass or more, 80% by mass or more, or 85% by mass or more. Activated carbon obtained by activating a carbonaceous material with a high carbon content in this way has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm). have in Therefore, the impregnated activated carbon obtained using such a carbonaceous material can have both adsorption performance for harmful substances other than mercury (Hg ⁰ ) and adsorption performance for mercury (Hg ⁰ ) at sufficiently high levels. .

The carbonaceous material having a carbon content of 70% by mass or more may be coal, for example, bituminous coal and anthracite coal. Therefore, as the carbonaceous material, a carbonaceous material containing at least one selected from the group consisting of bituminous coal and anthracite may be used.

The activation treatment of the carbon material may be performed by a normal gas activation treatment. For example, the carbon material may be heated at a temperature of 600 to 1000° C. or at a temperature of 750 to 900° C. in the presence of water vapor, carbon dioxide, air, oxygen, combustion gas, or a mixed gas thereof. . As a result, pores are formed in the carbonaceous material, and coal-derived porous activated carbon can be obtained.

The BET specific surface area of the activated carbon may be 600 m ² /g or more, or 800 cm ² /g or more, from the viewpoint of sufficiently increasing the adsorption performance of harmful substances (dioxins, etc.) other than mercury (Hg ⁰ ). , 900 m ² /g or more. The BET specific surface area of the activated carbon may be 1100 m ² /g or less, 1050 m ² /g or less, or 1000 m ² /g or less. As a result, sufficient micropores (larger micropores) having a size that allows the halogen compound to easily penetrate are secured, and the penetration of the halogen compound into the micropores (sufficiently small micropores) during attachment is promoted. can do. An example of the BET specific surface area of activated carbon is 600 to 1100 m ² /g or less.

A is the integrated value of the differential pore volume [dVp / d (dp)] with a pore diameter of 1 nm or less in the activated carbon, and the differential pore volume with a pore diameter of more than 1 nm and 2 nm or less [dVp / d (dp)]. When the integrated value is B, the following equations (1) and (2) may be satisfied.
A≧3 cm ³ /g/nm (1)
B/A≧0.2 (2)

By using such activated carbon, the adsorption performance of the impregnated activated carbon for mercury (Hg ⁰ ) can be sufficiently enhanced. From the same point of view, A may be 3.3 cm ³ /g/nm or more, and B/A may be 0.24 or more. From the viewpoint of sufficiently increasing the surface area of the activated carbon, A may be 5 cm ³ /g/nm or less. From the same point of view, B/A may be 0.5 or less.

The carbon content of the activated carbon measured by component analysis may be 70% by mass or more, 80% by mass or more, or 85% by mass or more. Activated carbon with such a high carbon content moderately has both sufficiently small micropores (pore size: 1 nm or less) and large micropores (pore size: 1 to 2 nm). Therefore, the impregnated activated carbon obtained by using such activated carbon can achieve both adsorption performance for harmful substances other than mercury (Hg ⁰ ) and adsorption performance for mercury (Hg ⁰ ) at a sufficiently high level.

A halogen compound of a diatomic molecule has a halogen element and an alkali metal element as constituent elements. The halogen compound may contain, for example, at least one selected from the group consisting of NaBr, KBr, NaCl and KCl. From the viewpoint of sufficiently increasing the London dispersion power, the halogen compound may contain bromide. These halogen compounds smoothly enter the larger micropores of the activated carbon and are retained inside the activated carbon. A halogen element can sufficiently exert the London dispersion force inside the activated carbon. This makes it easier for mercury (Hg ⁰ ) to be adsorbed in the pores, and the adsorption performance of mercury (Hg ⁰ ) can be sufficiently enhanced.

The impregnated activated carbon thus obtained is considered to have an internal structure as shown in FIG. 1, for example. The impregnated activated carbon 12 of FIG. 1 includes activated carbon 10 and a diatomic halogen compound 20 impregnated on the activated carbon. Pores 40 are formed near the surface of the activated carbon 10 . Pores 40 include sufficiently small micropores 40A and larger micropores 40B. Adsorption of mercury (Hg ⁰ ) requires such small micropores 40A. On the other hand, harmful substances other than mercury (Hg ⁰ ) can be adsorbed by both small micropores 40A and large micropores 40B.

In the step of impregnating the halogen compound, the halogen compound 20 smoothly enters through the large micropores 40B and is held within the pores 40. FIG. The London dispersion force of the halide 20 retained within the pores 40 extends over the broad region 22 shown in FIG. Therefore, mercury (Hg ⁰ ) 30 is adsorbed on the inner walls of micropores 40A included in region 22 . On the other hand, harmful substances other than mercury (Hg ⁰ ) such as dioxin are adsorbed by both micropores 40A and 40B.

On the other hand, in the case of a halogen compound, which is a molecule having three or more atoms, as shown in FIG . Instead, it adheres to the surface of the activated carbon 110 . In this case, the area 122 within the activated carbon 110 on which the London dispersion force acts becomes smaller. Therefore, the proportion of pores 140 that can adsorb mercury (Hg ⁰ ) 30 is reduced. Therefore, the impregnated activated carbon as shown in FIG. 9B cannot sufficiently adsorb mercury (Hg ⁰ ) 130 .

In addition, in the case of activated carbon with a small number of sufficiently small micropores, as shown in FIG . affects. However, the region 122 does not contain sufficiently small micropores to sufficiently adsorb mercury (Hg ⁰ ) 130 .

In addition, in the case of activated carbon which does not have large micropores and has only sufficiently small micropores, even if the size of the halogen compound is smaller than the sufficiently small micropores, it is not possible to exhibit sufficient adsorption capacity. . On the other hand, in the activated carbon 10 in the impregnated activated carbon 12 of FIG. 1, sufficiently small micropores 40A and larger micropores 40B are formed in a good balance. Such well-balanced formation of sufficiently small micropores 40A and larger micropores 40B is effective for exhibiting the adsorption ability. Furthermore, in the impregnated activated carbon 12 of FIG. Due to these synergistic effects, the impregnated activated carbon 12 of FIG. 1 can sufficiently adsorb mercury (Hg ⁰ ) 30 and harmful substances other than mercury than the impregnated activated carbon of FIG. 9 and the impregnated activated carbon without large micropores. can.

The impregnation of the halogen compound 20 on the activated carbon 10 is performed by spraying an aqueous solution of the halogen compound 20 . The concentration of the halogen compound 20 in the aqueous solution may be 40 g/100 mL or more, 50 g/100 mL or more, or 60 g/100 mL or more. "100 mL" here is the amount of water as a solvent. An aqueous solution having such a concentration suppresses precipitation of solids when sprayed, and can sufficiently penetrate into the pores 40 of the activated carbon 10 . The concentration of the halogen compound 20 in the aqueous solution may be 120 g/100 mL or less. If the concentration of the halogen compound 20 contained in the aqueous solution becomes too high, when the activated carbon 10 is impregnated, a region with a high concentration of the halogen compound 20 is generated, and the alkali metal that has entered the activated carbon 10 together with the halogen element becomes mercury (Hg ⁰ ). 30 may interfere with adsorption. An example concentration of the halogen compound 20 in the aqueous solution is 40-120 g/100 mL.

When the halogen compound 20 contains NaBr (sodium bromide), the content of NaBr in the aqueous solution may be 30-42 mass %. As a result, an appropriate amount of NaBr can be impregnated into the pores 40 of the activated carbon 10 while suppressing precipitation of NaBr. If the NaBr content in the aqueous solution becomes too low, the amount of NaBr impregnated decreases and the amount of water adsorbed increases, which tends to make it difficult to adsorb harmful substances. If the NaBr content in the aqueous solution becomes too high, NaBr tends to precipitate and crystallize, making it difficult to enter the pores 40 of the activated carbon 10 .

In the impregnated activated carbon 12, the impregnation ratio of the halogen compound 20 to the activated carbon 10 may be 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more. Thereby, the halogen compound 20 can be sufficiently impregnated into the pores 40 of the activated carbon 10 . The attachment ratio of the halogen compound 20 to the activated carbon 10 may be 5% by mass or less, or may be 4% by mass or less. If the attachment ratio is too high, the regions 22 in FIG. 1 are likely to overlap, making it difficult to effectively utilize the London dispersion force of the halogen element. In addition, the action of the alkali metal contained in the halogen compound 20 to hinder the adsorption of mercury (Hg ⁰ ) 30 may become apparent. An example of the attachment ratio of the halogen compound 20 to the activated carbon 10 is 1.5 to 5% by mass.

The BET specific surface area of the impregnated activated carbon 12 may be 600 m ² /g or more, 700 m ² /g or more, or 800 m ² /g or more. As a result, mercury (Hg ⁰ ) 30 and harmful substances other than mercury (Hg ⁰ ) can be sufficiently adsorbed. The BET specific surface area of the impregnated activated carbon 12 may be 1100 m ² /g or less, or may be 1000 m ² /g or less. As a result, the micropores 40B are sufficiently secured, and the infiltration of the halogen compound 20 can be promoted.

The impregnation of the halogen compound 20 to the activated carbon may be performed using a production facility equipped with a stirring device (ribbon blender) shown in FIGS. 2(A) and 2(B). This manufacturing facility includes a stirring device 50 for stirring a sediment layer of activated carbon, an introduction section 52 for introducing activated carbon into the stirring device 50, and an outlet section 54 for leading out the impregnated activated carbon obtained by the stirring device 50 from the stirring device 50. , provided. The stirring device 50 includes a ribbon-shaped stirring blade 72 for stirring the introduced deposited layer 11 of activated carbon, and a motor 70 for rotationally driving the stirring blade 72 . A nozzle 60 for spraying an aqueous solution of a halogen compound is provided on the upper wall of the stirring device 50 . An aqueous solution of a halogen compound is supplied from a pump 62 to the nozzle 60 . With this manufacturing equipment, the aqueous solution of the halogen compound can be sprayed from the nozzle 60 toward the deposited layer 11 of activated carbon in the stirring device 50 while stirring the activated carbon with the stirring blade 72 .

The droplet size of the aqueous solution sprayed from the nozzle 60 may be 100 to 300 μm. If the droplet diameter becomes too small, the aqueous solution floats and adheres to the inner wall surface of the stirring device 50, which tends to cause uneven adhesion. Even if the droplet diameter becomes too large, there is a tendency that uneven adhesion tends to occur.

FIG. 2(B) shows the surface of the deposited layer 11 of the activated carbon deposited layer 11 in the stirring device 50 when viewed from above, and the sprayed liquid from each nozzle 60 directly drops onto the surface. Area 64 is shown. The ratio of the total area (sprayed area) of the plurality of areas 64 to the total surface area of the deposited layer 11 may be 40 to 120%, or may be 50 to 100%. Thereby, the halogen compound can be sufficiently uniformly impregnated on the activated carbon. Note that the above area ratio may exceed 100% because the portion where the plurality of areas 64 overlap is counted redundantly. Note that the number of nozzles 60 is not particularly limited. Alternatively, the attachment may be performed without using a stirring device such as that shown in FIG.

The impregnated activated carbon according to one embodiment comprises activated carbon and a diatomic halogen compound impregnated on the activated carbon. The halogen compound may contain, for example, at least one selected from the group consisting of NaBr, KBr, NaCl and KCl. The carbon content of the activated carbon may be 70% by mass or more, 80% by mass or more, or 85% by mass or more. Activated carbon is a product of activated coal. Conditions for the activation treatment are as described above. Coal may include, for example, at least one selected from the group consisting of bituminous coal and anthracite.

The ratio of halogen compound (eg sodium bromide) to activated carbon may be 1.5 to 5% by weight. The loading ratio of the halogen compound 20 to the activated carbon may be 1.5% by mass or more, 2% by mass or more, or 2.5% by mass or more. The attachment ratio of the halogen compound 20 to the activated carbon may be 5% by mass or less, or may be 4% by mass or less. The impregnated activated carbon may be produced by the production method described above. Therefore, the description of the method for producing the impregnated activated carbon described above also applies to the impregnated activated carbon of the present embodiment.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

EXAMPLES The content of the present invention will be described in more detail with reference to examples , reference examples, and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
<Preparation of activated carbon>
Powdery carbonaceous materials derived from anthracite and bituminous coal were prepared as carbonaceous materials. The carbon content of this carbonaceous material was as shown in Table 1. This carbonaceous material was subjected to gas activation treatment to prepare activated carbon. The gas activation treatment was performed by heating the carbon material using a gas containing water vapor.

<Evaluation of activated carbon>
The component analysis of the activated carbon obtained by the above procedure was performed to determine the carbon content. The details of the analysis equipment and analysis method are as follows.
Analysis method: X-ray analysis with electron microscope Equipment used: Scanning electron microscope JSM-6390 type (manufactured by JEOL Ltd.)
Target elements: B to U
Correction method: ZAF method

The result of component analysis was as shown in FIG. In addition, the BET specific surface area of the activated carbon was measured using a specific surface area/pore analysis measurement device (manufactured by Microtrack Bell Co., device name: BELSORP mini II). The measurement method was the _N2 adsorption method. These results were as shown in Table 1. Mercury adsorption performance of this activated carbon was evaluated by the following procedure.

Impregnated activated carbon (0.05 g) was packed inside a column chromatography tube (inner diameter: 30 mm, length: 30 cm) (packing height: 15 cm). A heater was wrapped around the column chromatography tube to heat the inside of the column chromatography tube to 180 to 220°C. A feed gas with a mercury concentration of 500 μg/m ³ was prepared by entraining the air with mercury vapor using a mercury vapor generator. This supply gas was heated to 220° C. and supplied to the above column chromatography tube for gas treatment. The mercury (Hg ⁰ ) concentration in the exhaust gas discharged from the column chromatography tube was measured using a mercury measuring device (manufactured by Nippon Instruments Co., Ltd., product name: EMP-2). Gas treatment and concentration measurement of mercury (Hg ⁰ ) in the exhaust gas were continued for about 3 hours. From the difference between the average concentration of mercury (Hg ⁰ ) in the supplied gas and the average concentration of mercury (Hg ⁰ ) contained in the exhaust gas, the removal rate of mercury (Hg ⁰ ) was calculated by the following formula. . The results were as shown in Table 1.

Mercury (Hg ⁰ ) removal rate (%) = (Mercury concentration in supply gas - Mercury concentration in exhaust gas) / Mercury concentration in supply gas

<Production of impregnated activated carbon>
An aqueous solution was obtained by dissolving sodium bromide (NaBr) in water. The NaBr concentration in the aqueous solution was set to 41% by mass. After about 20 g of activated carbon was placed in a plastic container, the aqueous solution was sprayed onto the activated carbon with a sprayer. The spray amount of the aqueous solution to the activated carbon was set so that the impregnation ratio to the activated carbon was 3.5% by mass. Thus, the impregnated activated carbon was obtained by impregnating the activated carbon with sodium bromide. After the aqueous solution was sprayed, the plastic container was shaken well so that NaBr was sufficiently impregnated with the activated carbon.

<Evaluation of impregnated activated carbon>
After impregnation, the impregnated activated carbon was sufficiently dried. After that, the BET specific surface area and the removal rate (%) of mercury (Hg ⁰ ) were measured by the same method as the above-mentioned "evaluation of activated carbon". Also, the impregnation ratio of NaBr to activated carbon was determined by bromide analysis (automatic combustion-ion chromatography method). The results were as shown in Table 1.

(Comparative example 1)
An impregnated activated carbon was produced in the same manner as in Example 1, except that lignite (brown coal) was used as the carbon material. The carbon content of this lignite was well below 70% by mass. And each evaluation was performed by the same method as Example 1. The results were as shown in Table 1. FIG. 4 shows the result of component analysis of the impregnated activated carbon.

(Comparative example 2)
Activated carbon and impregnated activated carbon were produced in the same manner as in Example 1, except that commercially available coconut shell carbon was used as the carbon material. And each evaluation was performed by the same method as Example 1. The results were as shown in Table 1.

As shown in Table 1, since the impregnated activated carbon of Example 1 has a sufficiently high specific surface area, it has excellent adsorption performance for harmful substances (such as dioxin) other than mercury (Hg ⁰ ). It was also confirmed that the adsorption amount of mercury (Hg ⁰ ) was sufficiently excellent. On the other hand, the mercury (Hg ⁰ ) removal rate of the impregnated activated carbon of Comparative Examples 1 and 2 was lower than that of Example 1. Since the impregnated activated carbon of Comparative Example 1 has a small specific surface area, this is considered to be the cause of the low adsorption amount of mercury (Hg ⁰ ). Such impregnated activated carbon is considered to have low adsorption performance for harmful substances (such as dioxins) other than mercury (Hg ⁰ ). The specific surface area of the impregnated activated carbon of Comparative Example 2 was larger than that of the impregnated activated carbon of Example 1. Nevertheless, the mercury (Hg ⁰ ) removal rate of the impregnated activated carbon of Comparative Example 2 was lower than that of Example 1. The cause of this is discussed below.

The pore size distribution of the carbonaceous materials (anthracite, lignite, biomass coal) used in Example 1 and Comparative Examples 1 and 2 was measured, and the differential pore volume [dVp/ _d (dp) for each pore size (d p ) ] asked. For the measurement, a specific surface area/pore analysis measurement device (manufactured by Microtrack Bell Co., Ltd., device name: BELSORP mini II) was used. The results were as shown in Table 2 and FIG. From these results, the integrated value (A) of the differential pore volume [dVp / d (dp)] with a pore diameter of 1 nm or less, and the differential pore volume with a pore diameter of more than 1 nm and 2 nm or less [dVp / d (dp)] and their ratio (B/A) were obtained. These results were as shown in Table 2. In Table 2, the numerical value of B/A is a dimensionless number.

As shown in Table 2 and FIG. 5, the carbonaceous material of Comparative Example 2 has a higher ratio of pores with a pore diameter of 1 nm or less than the carbonaceous material of Example 1, but the ratio of pores with a pore diameter of 1 to 2 nm. was confirmed to be small. For this reason, in the case of activated carbon produced using coconut shell coal, the impregnated halogen compound cannot sufficiently penetrate into the interior of the activated carbon particles, and the proportion of the halogen compound impregnated on the surface of the activated carbon increases. It is assumed that there are For this reason, the pores that can adsorb mercury (Hg ⁰ ) are limited, and in the measurement of the removal rate (%) of mercury (Hg ⁰ ), breakthrough occurs early. On the other hand, the carbonaceous material derived from anthracite and bituminous coal used in Example 1 contains pores with a pore diameter of 1 nm or less and pores with a pore diameter of 1 to 2 nm in a well-balanced manner. It is presumed that this allows the halogen compound to sufficiently penetrate into the inside of the particles of activated carbon, and that there are sufficient pores for adsorbing mercury (Hg ⁰ ) due to the London dispersion force.

Next, Examples 2 to 4 were carried out in order to investigate the influence of the concentration of the aqueous solution of the halogen compound.

(Examples 2-4)
Impregnated activated carbon was produced in the same manner as in Example 1, except that the NaBr concentration in the aqueous solution was as shown in Table 3. In both cases, the amount of the aqueous solution was set so that the NaBr impregnation ratio with respect to the activated carbon was 3.5% by mass. By the same method as in Example 1, the NaBr impregnation ratio and mercury (Hg ⁰ ) removal rate (%) of the impregnated activated carbon obtained in each example were measured. The results were as shown in Table 3. Table 3 also shows the results of Example 1 for comparison.

From the results of Examples 1 to 3, it was confirmed that the higher the concentration of NaBr in the aqueous solution, the greater the adsorption amount of mercury (Hg ⁰ ) at the impregnation ratio. This is presumed to be due to the fact that the amount of water molecules adsorbed on the surfaces of the pores of the activated carbon is reduced and that NaBr efficiently penetrates into the particles of the activated carbon through the pores. The solubility of NaBr at room temperature (20° C.) is 73.3 g/100 mL, and the NaBr concentration at this time is 42.3% by mass. In Example 4, since part of NaBr did not dissolve at 20°C, the aqueous solution was heated to about 50°C to dissolve and then sprayed. However, the adsorption amount of mercury (Hg ⁰ ) in Example 4 was lower than that in Example 1. The reason for this is presumed to be that NaBr precipitated and crystallized when it was impregnated with the activated carbon, making it difficult for NaBr to enter the pores of the activated carbon. In Example 4, the impregnation ratio of NaBr greatly exceeded the target of 3.5% by mass. The reason for this is considered to be that the portion where NaBr is crystallized was sampled during the component analysis.

Next, Examples 5 and 6 were carried out in order to investigate the effect of the attachment ratio of the halogen compound.

(Examples 5 and 6)
Impregnated activated carbon was prepared in the same manner as in Example 3, except that the amount of NaBr sprayed onto the activated carbon was changed to change the amount of NaBr impregnated on the activated carbon. In Examples 5 and 6, the impregnation ratio of NaBr was calculated from the difference in mass before and after spraying and the concentration of the aqueous solution.

By the same method as in Example 1, the removal rate (%) of mercury (Hg ⁰ ) from the impregnated activated carbon obtained in Examples 5 and 6 was measured. The results were as shown in Table 4. Table 4 also shows the results of Example 3 for comparison.

From the results of Examples 3, 5, and 6, it was confirmed that when the impregnation ratio of NaBr is too high, the adsorption amount of mercury (Hg ⁰ ) decreases. A possible reason for this is that when the halogen element is too dense in the pores of the activated carbon, it becomes difficult for mercury (Hg ⁰ ) to enter the pores. Another factor is the increase in Na, which inhibits the adsorption of mercury (Hg ⁰ ). From the results in Table 4, it is considered that the ratio of NaBr to activated carbon (impregnated ratio) is preferably about 1.5 to 5% by mass.

Next, Examples 7 to 8 and Reference Example 9 were conducted in order to investigate the influence of the particle size of the impregnated activated carbon.

(Examples 7 and 8)
Impregnated activated carbons of Examples 7 and 8 were prepared in the same manner as in Examples 5 and 6, except that the amount of NaBr to be sprayed was changed to change the impregnation ratio of NaBr to the activated carbon. In Examples 7 and 8, the impregnation ratio of NaBr was calculated from the difference in mass before and after spraying and the concentration of the aqueous solution. The impregnation ratio of NaBr to activated carbon was 3.5% by mass and 5.0% by mass, respectively. Each of these impregnated activated carbons had a BET specific surface area of 1100 m ² /g and a bulk specific gravity of 480 kg/m ³ . These were molded into pellets to obtain granular impregnated activated carbon with a particle size of 4 mm.

The mercury (Hg ⁰ ) removal rate of the granular impregnated activated carbon thus obtained was measured in the same manner as in Example 1. However, the measurement was performed by changing the filling height of the impregnated activated carbon in the column chromatography tube (inner diameter: 30 mm, length: 30 cm) and the mercury concentration in the gas supplied to the column chromatography tube as shown in Table 5. The results were as shown in Table 5.

It was confirmed that the impregnated activated carbon molded into pellets can sufficiently adsorb mercury as well as the powdered impregnated activated carbon. Next, the effect of the type of attached compound was investigated.

( Reference example 9)
<Production of impregnated activated carbon>
An aqueous solution was obtained by dissolving sodium chloride (NaCl) in water. The NaCl concentration in the aqueous solution was set to 25.3% by mass. After about 20 g of activated carbon was placed in a plastic container, the aqueous solution was sprayed onto the activated carbon with a sprayer. The spray amount of the aqueous solution to the activated carbon was set so that the impregnation ratio of NaCl to the activated carbon was 4.4% by mass. After the aqueous solution was sprayed onto the activated carbon, the plastic container was shaken well to impregnate the activated carbon with NaCl. Thus, an impregnated activated carbon in which sodium chloride was impregnated on activated carbon was obtained.

<Evaluation of impregnated activated carbon>
After sufficiently drying the impregnated activated carbon, the removal rate (%) of mercury (Hg ⁰ ) was measured in the same manner as in Example 1. However, the measurement was performed by changing the mercury concentration in the gas supplied to the column chromatography tube (inner diameter: 30 mm, length: 30 cm) as shown in Table 6. The results were as shown in Table 6. For the impregnated activated carbon of Example 1, the removal rate (%) of mercury (Hg ⁰ ) was also measured under the same conditions as for the impregnated activated carbon of Reference Example 9. The results were as shown in Table 6.

As shown in Table 6, it was confirmed that even NaCl as the impregnated material was sufficiently excellent in the adsorption of mercury. It was determined that NaBr became more dominant than NaCl at higher mercury concentrations in the feed gas.

Next, NaBr was impregnated using manufacturing equipment equipped with a ribbon blender and a nozzle, and mass production was studied.

( Reference example 10)
<Production of impregnated activated carbon>
500 kg of activated carbon produced by the same procedure as in Example 1 was placed in a stirring device 50 (ribbon blender) of the manufacturing facility as shown in FIGS. 6(A) and 6(B). While stirring the activated carbon, the same NaBr aqueous solution as in Example 1 was sprayed onto the activated carbon from the nozzle 60A for 20 minutes. The droplet size was 300-600 μm. The total amount of the NaBr aqueous solution sprayed from the four nozzles 60A was set so that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass.

FIG. 6(B) is a view of the interior of the stirring device 50 viewed from above, cut along line VIb--VIb of FIG. 6(A). FIG. 6(B) shows an area 64 on the surface of the deposited layer 11 where the liquid sprayed from each nozzle 60A directly drops when the deposited layer 11 of the impregnated activated carbon in the stirring device 50 is viewed from above. there is The total area (spray area) of the four areas 64 and the ratio (area ratio) of the total area of the area 64 to the entire area of the surface of the deposition layer 11 were calculated. These results were as shown in Table 7. In this way, the activated carbon was stirred with the stirring blade 72 while spraying the aqueous solution from the nozzle 60</b>A so that the aqueous solution directly dropped onto a portion of the surface of the sediment layer 11 . Thus, the impregnated activated carbon was produced.

<Evaluation of impregnated activated carbon>
After sufficiently drying the impregnated activated carbon, the removal rate (%) of mercury (Hg ⁰ ) was measured in the same manner as in Example 1. However, the measurement was performed by changing the mercury concentration in the gas supplied to the column chromatography tube (inner diameter: 30 mm, length: 30 cm) as shown in Table 8. The results were as shown in Table 8. The impregnated activated carbon of Example 1 was also measured for the removal rate (%) of mercury (Hg ⁰ ) under the same conditions as the impregnated activated carbon of Reference Example 10. The results were as shown in Table 8.

(Example 11)
Impregnated activated carbon was produced and evaluated in the same manner as in Reference Example 10, except that a production facility equipped with a stirring device 50 (ribbon blender) and a nozzle 60B as shown in FIGS. 7(A) and 7(B) was used. did Since the nozzle 60B of this manufacturing facility was of a type that sprayed at a wider angle than the nozzle 60A, the number of nozzles was two. The droplet size was 100-300 μm.

FIG. 7B is a view of the interior of the stirring device 50 viewed from above, cut along line VIIb-VIIb of FIG. 7A. FIG. 7(B) shows the surface of the deposited layer 11 when the deposited layer 11 of the impregnated activated carbon in the stirring device 50 is viewed from above, and the area of the surface where the spray liquid from each nozzle 60B directly falls. 64 is shown. The total area (spray area) of the two areas 64 and the ratio (area ratio) of the total area of the area 64 to the entire area of the surface of the deposition layer 11 were calculated. These results were as shown in Table 7. The total amount of the NaBr aqueous solution sprayed from the two nozzles 60B was set so that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass. Table 8 shows the measurement results of the removal rate (%) of mercury (Hg ⁰ ).

(Example 12)
Impregnated activated carbon was produced and evaluated in the same manner as in Example 11, except that a production facility equipped with a stirring device 50 (ribbon blender) and a nozzle 60B as shown in FIGS. 8(A) and 8(B) was used. did Four nozzles 60B used in Example 11 were installed on the upper surface of this stirring device 50 . Therefore, the droplet size was 100-300 μm.

FIG. 8(B) is a view of the interior of the stirring device 50 viewed from above, cut along line VIIIb-VIIIb of FIG. 8(A). FIG. 8(B) shows the surface of the deposited layer 11 when the deposited layer 11 of the impregnated activated carbon in the stirring device 50 is viewed from above, and the area of the surface where the spray liquid from each nozzle 60B directly falls. 64 are shown. The total area (spray area) of the four areas 64 and the ratio (area ratio) of the total area of the area 64 to the entire area of the surface of the deposition layer 11 were calculated. Although the areas 64 partially overlap each other, the area of each area 64 was multiplied by four to calculate the total area (spray area) without correcting the overlapping portion. These results were as shown in Table 7. The total amount of the NaBr aqueous solution sprayed from the four nozzles 60B was set so that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass. Table 8 shows the measurement results of the removal rate (%) of mercury (Hg ⁰ ).

As shown in Tables 7 and 8, it was confirmed that an impregnated activated carbon having excellent mercury adsorption performance can be obtained by increasing the spray area. It is considered that this is because the uniformity of the distribution of halogen elements that contribute to adsorption is improved.

Provided are an impregnated activated carbon having sufficiently excellent adsorption performance for mercury (Hg ⁰ ) while maintaining adsorption performance for harmful substances other than mercury (Hg ⁰ ), and a method for producing the same. Provided is a production facility for impregnated activated carbon having sufficiently excellent mercury (Hg ⁰ ) adsorption performance.

10, 110, 111 Activated carbon 11 Sediment layer 12 Impregnated activated carbon 20 Halogen compound 22 Region 40 Pore 40A, 40B Micropore 50 Stirrer 52 Introduction part 54 ... Derivation part, 60, 60A, 60B ... Nozzle, 62 ... Pump, 64 ... Area, 70 ... Motor, 72 ... Stirring blade, 120 ... Halogen compound, 122 ... Region, 140 ... Pore.

Claims (10)

A step of spraying an aqueous solution of sodium bromide onto activated carbon obtained by activating a carbonaceous material to impregnate the activated carbon with the sodium bromide;
The carbon material contains coal, the carbon content of the activated carbon is 70% by mass or more, and the integrated value of the differential pore volume [dVp/d (dp)] at which the pore diameter of the activated carbon is 1 nm or less is calculated. When A [cm ³ /g/nm] and the integrated value of the differential pore volume [dVp/d(dp)] with a pore diameter of more than 1 nm and 2 nm or less being B [cm ³ /g/nm], the following A method for producing impregnated activated carbon for adsorbing mercury in gas, which satisfies formulas (1) and (2).
3≤A≤5 (1)
0.2≤B/A≤0.5 (2) 2. The method for producing impregnated activated carbon according to claim 1, wherein the carbon content of the carbonaceous material is 70% by mass or more. The method for producing impregnated activated carbon according to claim 1 or 2, wherein the carbonaceous material includes at least one selected from the group consisting of bituminous coal and anthracite. The method for producing impregnated activated carbon according to any one of claims 1 to 3, wherein an impregnated ratio of said sodium bromide to said activated carbon is 1.5 to 5% by mass. The method for producing impregnated activated carbon according to any one of claims 1 to 4, wherein the impregnated activated carbon has a specific surface area of 600 to 1100 m ² /g. The method for producing impregnated activated carbon according to any one of claims 1 to 5, wherein the aqueous solution has a concentration of sodium bromide of 40 to 120 g/100 mL. The method for producing impregnated activated carbon according to any one of claims 1 to 6, wherein the sodium bromide concentration in the aqueous solution is 30 to 42% by mass. The impregnated activated carbon is obtained by using a stirring device for stirring the activated carbon and a nozzle for spraying the aqueous solution, and spraying the aqueous solution from the nozzle onto the activated carbon while stirring the activated carbon with the stirring device. 8. A method for producing impregnated activated carbon according to any one of 1 to 7. Comprising activated carbon and sodium bromide impregnated on the activated carbon,
The activated carbon is an activated coal product having a carbon content of 70% by mass or more,
The ratio of sodium bromide to the activated carbon is 1.5 to 5% by mass, and the integrated value of the differential pore volume [dVp/d (dp)] when the pore diameter in the activated carbon is 1 nm or less is A [cm ³ /g/nm], and the integrated value of the differential pore volume [dVp/d(dp)] with a pore diameter of more than 1 nm and 2 nm or less is B [cm ³ /g/nm], the following formula (1 ) and (2), an impregnated activated carbon for adsorbing mercury in gas.
3≤A≤5 (1)
0.2≤B/A≤0.5 (2) a stirring device for stirring a sediment layer of coal-derived activated carbon;
an introduction section for introducing the activated carbon having a carbon content of 70% by mass or more into the stirring device;
An aqueous solution of sodium bromide with a concentration of 30 to 42% by mass is poured from above the sediment layer toward the sediment layer, and when the sediment layer in the stirring device is viewed from above, the entire surface area of the sediment layer A nozzle that sprays so that the ratio of the spray area of the aqueous solution is 50 to 120%,
an impregnated activated carbon manufacturing facility, comprising: a lead-out unit for leading out the impregnated activated carbon impregnated with sodium bromide from the stirring device.

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