JP2023140485A - Loaded activated carbon and method for producing the same, and production equipment for loaded activated carbon - Google Patents

Abstract

To provide a method for producing loaded activated carbon with sufficiently excellent mercury (Hg0) adsorptivity.SOLUTION: A method for producing loaded activated carbon includes the step for spraying activated carbon 10, prepared by activating carbon material, with an aqueous solution of a diatomic halogen compound 20, to load the activated carbon 10 with the halogen compound 20. The carbon material includes coal, and the activated carbon 10 has a carbon content of 70 mass% or more.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to impregnated activated carbon, a method for manufacturing the same, and equipment for manufacturing impregnated activated carbon.

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

Japanese Patent Application Publication No. 2002-102653 JP2020-199425A

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 impregnated activated carbon that has sufficiently excellent mercury (Hg ⁰ ) adsorption performance and a method for producing the same. Furthermore, the present invention provides equipment for producing impregnated activated carbon that has sufficiently excellent adsorption performance for mercury (Hg ⁰ ).

In one aspect, the present disclosure includes 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. Provided is a method for producing impregnated activated carbon that contains coal and has a carbon content of 70% by mass or more.

In the above manufacturing method, a diatomic halogen compound is used as a compound attached to activated carbon. Since such diatomic halogen compounds have small molecular sizes, they easily penetrate into the micropores of activated carbon. Here, 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. Furthermore, the activated carbon has sufficiently small micropores as well as larger 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 effect) cannot be fully exerted, but in the above production method, the halogen element is retained inside the activated carbon. Therefore, the London dispersion force of the halogen element can be fully exhibited. Therefore, the mercury (Hg ⁰ ) adsorption performance 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 carbon material has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm) at an appropriate level. Therefore, the impregnated activated carbon obtained using such a carbon material 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. .

In the above manufacturing method, the carbonaceous material may include at least one selected from the group consisting of bituminous coal and anthracite coal. Such a carbon material has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm) at an appropriate level. Therefore, the impregnated activated carbon obtained using such a carbon material 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. .

In the above production method, the impregnation ratio of the halogen compound 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 impregnated activated carbon produced by the above production method may have a specific surface area of 600 to 1100 m ² /g. Such impregnated activated carbon has sufficient adsorption performance for harmful substances other than mercury (Hg ⁰ ).

The integrated value of the differential pore volume [dVp/d(dp)] in which the pore diameter is 1 nm or less in the activated carbon produced by the above production method is A, and the differential pore volume [dVp/d(dp)] in which the pore diameter is greater than 1 nm and 2 nm or less is dp)], the following equations (1) and (2) may be satisfied.
A≧ ^3cm3 /g/nm (1)
B/A≧0.2 (2)

Such activated carbon has sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 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 dispersion power of the halogen element is fully exerted, making the adsorption performance of mercury (Hg ⁰ ) sufficiently high. be able to.

The concentration of the halogen compound in the aqueous solution may be between 40 and 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. In such an aqueous solution, sodium bromide does not precipitate and can be stably dissolved even at room temperature. By using such an aqueous solution, bromine can be appropriately dispersed and impregnated inside the micropores of activated carbon. Such impregnated activated carbon has higher mercury (Hg ⁰ ) adsorption performance.

In the above manufacturing method, using a stirring device that stirs the activated carbon and a nozzle that sprays the aqueous solution, the aqueous solution may be sprayed onto the activated carbon from the nozzle while stirring the activated carbon with the stirring device to obtain impregnated activated carbon. As a result, the halogen compound is impregnated onto the activated carbon with high uniformity. Therefore, impregnated activated carbon having sufficiently excellent adsorption performance for mercury (Hg ⁰ ) 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 an activated product of coal and has a carbon content of 70% by mass or more, and the activated carbon has an odor. The impregnated activated carbon has a sodium content of 1.5 to 5% by weight.

Such impregnated activated carbon is an activated product of coal and contains activated carbon having a carbon content of 70% by mass or more. Such activated carbon has a suitable amount of both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm). Therefore, the adsorption performance for harmful substances other than mercury (Hg ⁰ ) can be maintained. Moreover, bromine can be stably retained inside the activated carbon. Therefore, the London dispersion force is fully exhibited, and the mercury (Hg ⁰ ) adsorption performance can be sufficiently increased.

In one aspect, the present disclosure includes a stirring device that stirs a deposited layer of activated carbon derived from coal, an introduction part that introduces activated carbon having a carbon content of 70% by mass or more into the stirring device, and a carbon deposited from above the deposited layer. Provided is a production facility for impregnated activated carbon, which includes a nozzle that sprays an aqueous solution of a diatomic halogen compound toward a layer, and a delivery section that leads out the impregnated activated carbon impregnated with the halogen compound from a stirring device.

The above manufacturing equipment uses activated carbon derived from coal and having a carbon content of 70% by mass or more and a diatomic halogen compound. Since the diatomic molecule halogen compound has a small molecular size, it easily penetrates into the micropores of 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. Furthermore, the activated carbon has sufficiently small micropores as well as larger micropores (pore diameter: 1 to 2 nm). Therefore, the halogen compound in the aqueous solution sprayed from the nozzle 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 effect) cannot be fully exerted. However, in the above manufacturing equipment, the impregnated activated carbon with the halogen element retained inside the activated carbon is released from the lead-out section. derived. Such impregnated activated carbon can fully exhibit the London dispersion force due to the halogen element. Therefore, the above production equipment can produce impregnated activated carbon that has sufficiently excellent adsorption performance for mercury (Hg ⁰ ).

The aqueous solution is sprayed from the nozzle so that when the deposited layer in the stirring device is viewed from above, the ratio of the spray area of the aqueous solution from the nozzle to the entire surface area of the deposited layer is 40 to 120%. It's fine. This allows the halogen compound to be impregnated onto the activated carbon with high uniformity.

It is possible to provide impregnated activated carbon that has 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 that has sufficiently excellent adsorption performance for mercury (Hg ⁰ ).

FIG. 3 is a diagram schematically showing an example of a cross section near the surface of impregnated activated carbon. It is a figure showing an example of the manufacturing device used for the manufacturing method of impregnated activated carbon. (A) is a diagram when the device is viewed from the side, and (B) is a diagram when the interior is viewed from above when cut along line IIb-IIb in (A). FIG. 3 is a diagram showing the results of component analysis of activated carbon of Example 1. 3 is a diagram showing the results of component analysis of impregnated activated carbon of Comparative Example 1. FIG. FIG. 2 is a diagram showing the distribution of differential pore volume [dVp/d(dp)] of activated carbon used in Example 1 and Comparative Examples 1 and 2. FIG. 7 is a diagram showing a manufacturing apparatus used in Example 10. (A) is a view when the device is viewed from the side, and (B) is a view when the inside of the device is viewed from above when cut along line VIb-VIb in (A). FIG. 7 is a diagram showing a manufacturing apparatus used in Example 11. (A) is a diagram when the device is viewed from the side, and (B) is a diagram when the inside of the device is viewed from above when cut along line VIIb-VIIb in (A). FIG. 7 is a diagram showing a manufacturing apparatus used in Example 12. (A) is a view when the device is viewed from the side, and (B) is a view when the inside of the device is viewed from above when cut along line VIIIb-VIIIb in (A). (A) and (B) are diagrams schematically showing a cross section near the surface of impregnated activated carbon of a comparative example.

Hereinafter, one embodiment of the present disclosure will be described 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 will be used for the same elements or elements having the same function, and redundant description will be omitted in some cases. In addition, the positional relationships such as top, bottom, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratio of each element is not limited to the ratio shown in the drawings.

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

The carbon content of the carbonaceous 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 carbon materials with high carbon content has both sufficiently small micropores (pore diameter: 1 nm or less) and large micropores (pore diameter: 1 to 2 nm). has. Therefore, the impregnated activated carbon obtained using such a carbon material 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. .

The carbon material having a carbon content of 70% by mass or more may be coal, and examples thereof include bituminous coal and anthracite coal. Therefore, the carbon material may include at least one selected from the group consisting of bituminous coal and anthracite coal.

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

The BET specific surface area of the activated carbon may be 600 m ² /g or more, and may be 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. This ensures that there are sufficient micropores (large micropores) that are large enough for the halogen compound to easily penetrate, and facilitates the penetration of the halogen compound into the micropores (sufficiently small micropores) during attachment. 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)] in activated carbon where the pore diameter is 1 nm or less, and A is the integrated value of the differential pore volume [dVp/d(dp)] where the pore diameter is more than 1 nm and 2 nm or less. When the integrated value is B, the following formulas (1) and (2) may be satisfied.
A≧ ^3cm3 /g/nm (1)
B/A≧0.2 (2)

By using such activated carbon, the mercury (Hg ⁰ ) adsorption performance of the impregnated activated carbon can be made sufficiently high. From the same viewpoint, 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 viewpoint, 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 has a suitable amount of 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 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 diatomic molecule halogen compound has a halogen element and an alkali metal element as constituent elements. The halogen compound may include, 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 force, 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. The halogen element can fully exhibit the London dispersion force inside the activated carbon. As a result, mercury (Hg ⁰ ) is easily adsorbed into the pores, and the adsorption performance of mercury (Hg ⁰ ) can be made sufficiently high.

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

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

On the other hand, in the case of a halogen compound that is a molecule with three or more atoms, as shown in FIG. First, it is attached to the surface of activated carbon 110. In this case, the region 122 within the activated carbon 110 that is affected by the London dispersion force becomes small. Therefore, the proportion of pores 140 that can adsorb mercury (Hg ⁰ ) 30 becomes small. Therefore, impregnated activated carbon as shown in FIG. 9(A) cannot sufficiently adsorb mercury (Hg ⁰ ) 130.

In addition, in the case of activated carbon with few sufficiently small micropores, the halogen compound penetrates into the activated carbon 111 through the large micropores and applies the London dispersion force to a relatively wide area 122, as shown in FIG. 9(B). affect However, since there are few sufficiently small micropores included in the region 122, mercury (Hg ⁰ ) 130 cannot be sufficiently adsorbed.

In addition, activated carbon that does not have large micropores and only has sufficiently small micropores cannot exhibit sufficient adsorption ability even if the size of the halogen compound is smaller than the sufficiently small micropores. . 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. In this way, forming the sufficiently small micropores 40A and the larger micropores 40B in a well-balanced manner is effective for exhibiting the adsorption ability. Furthermore, in the impregnated activated carbon 12 of FIG. 1, a diatomic molecule halogen compound 20 is held inside the activated carbon 10. Due to these synergistic effects, the impregnated activated carbon 12 in FIG. 1 is able to adsorb mercury (Hg ⁰ ) 30 and harmful substances other than mercury more fully than the impregnated activated carbon in FIG. 9 and the impregnated activated carbon without large micropores. can.

The halogen compound 20 is impregnated onto the activated carbon 10 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 which is a solvent. With an aqueous solution having such a concentration, precipitation of solid content is suppressed when sprayed, and the aqueous solution 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, a dense region of the halogen compound 20 will occur when the halogen compound 20 is impregnated onto the activated carbon 10, and the alkali metal that has entered into the activated carbon 10 together with the halogen element will become mercury (Hg ⁰ ). 30 may be prevented from being adsorbed. An example of the concentration of the halogen compound 20 in the aqueous solution is 40 to 120 g/100 mL.

When the halogen compound 20 contains NaBr (sodium bromide), the content of NaBr in the aqueous solution may be 30 to 42% by mass. Thereby, an appropriate amount of NaBr can be impregnated into the pores 40 of the activated carbon 10 while suppressing the precipitation of NaBr. If the content of NaBr in the aqueous solution becomes too low, the amount of NaBr impregnated will decrease and the amount of water adsorbed will increase, making it difficult to adsorb harmful substances. If the content of NaBr 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 attached to the pores 40 of the activated carbon 10. The impregnation ratio of the halogen compound 20 to the activated carbon 10 may be 5% by mass or less, and may be 4% by mass or less. If the impregnation ratio becomes too high, the regions 22 in FIG. 1 tend to overlap, making it difficult to effectively utilize the London dispersion force of the halogen element. Furthermore, there is a possibility that the effect of the alkali metal contained in the halogen compound 20 preventing the adsorption of mercury (Hg ⁰ ) 30 becomes apparent. An example of the impregnation 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. Thereby, 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 1000 m ² /g or less. This makes it possible to sufficiently secure the micropores 40B and promote the penetration of the halogen compound 20.

The halogen compound 20 may be impregnated onto the activated carbon using a production facility equipped with a stirring device (ribbon blender) shown in FIGS. 2(A) and 2(B). This manufacturing equipment includes a stirring device 50 that stirs a deposited layer of activated carbon, an introduction section 52 that introduces activated carbon into the stirring device 50, and a derivation section 54 that leads out the impregnated activated carbon obtained by the stirring device 50 from the stirring device 50. , is provided. The stirring device 50 includes a ribbon-shaped stirring blade 72 that stirs the deposited layer 11 of activated carbon that has been introduced, and a motor 70 that rotationally drives 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 to the nozzle 60 from a pump 62 . 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 diameter 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 will float and adhere to the inner wall surface of the stirring device 50, tending to cause uneven adhesion. Even if the droplet diameter becomes too large, uneven adhesion tends to occur.

FIG. 2(B) shows the surface of the activated carbon deposit layer 11 when viewed from above in the stirring device 50, and the spray liquid from each nozzle 60 falls directly onto the surface. Area 64 is shown. The ratio of the total area (sprayed area) of the plurality of areas 64 to the entire surface area of the deposited layer 11 may be 40 to 120%, or 50 to 100%. This allows the halogen compound to be impregnated onto the activated carbon sufficiently and uniformly. Note that since areas where a plurality of areas 64 overlap are counted redundantly, the area ratio may exceed 100%. Note that the number of nozzles 60 is not particularly limited. Further, the impregnation may be performed without using a stirring device as shown in FIG.

The impregnated activated carbon according to one embodiment includes activated carbon and a diatomic halogen compound impregnated to the activated carbon. The halogen compound may include, 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 an activated product of coal. The conditions for the activation treatment are as described above. The coal may include, for example, at least one selected from the group consisting of bituminous coal and anthracite coal.

The ratio of halogen compound (eg sodium bromide) to activated carbon may be from 1.5 to 5% by weight. The impregnation 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 impregnation ratio of the halogen compound 20 to the activated carbon may be 5% by mass or less, and may be 4% by mass or less. Impregnated activated carbon may be manufactured by the above-mentioned manufacturing method. Therefore, the content of the explanation regarding the method for producing impregnated activated carbon described above also applies to the impregnated activated carbon of this embodiment.

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

The contents of the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
<Preparation of activated carbon>
Powdered carbonaceous materials derived from anthracite and bituminous coal were prepared as carbonaceous materials. The carbon content of this carbon material was as shown in Table 1. This carbon 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>
Component analysis of the activated carbon obtained by the above procedure was performed to determine the carbon content. Details of the analytical device and analytical 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~U
Correction method: ZAF method

The results of component analysis were as shown in FIG. Further, the BET specific surface area of the activated carbon was measured using a specific surface area/pore analysis measuring device (manufactured by Microtrac Bell Co., Ltd., device name: BELSORP mini II). The measurement method was N ₂ adsorption method. These results were as shown in Table 1. The mercury adsorption performance of this activated carbon was evaluated using the following procedure.

Impregnated activated carbon (0.05 g) was packed inside a column chromatography tube (inner diameter: 30 mm, length: 30 cm) (filling 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 mixing air with mercury vapor using a mercury vapor generator. This supplied gas was heated to 220° C. and supplied to the above-mentioned 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 measurement of the concentration of mercury (Hg ⁰ ) in the exhaust gas were continued for about 3 hours. The removal rate of mercury (Hg ⁰ ) was calculated using the following formula 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 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>
Sodium bromide (NaBr) was dissolved in water to obtain an aqueous solution. The NaBr concentration in the aqueous solution was 41% by mass. After about 20 g of activated carbon was placed in a plastic container, the above aqueous solution was sprayed onto the activated carbon using a sprayer. The amount of spraying of the aqueous solution to the activated carbon was set so that the impregnation ratio to the activated carbon was 3.5% by mass. In this way, activated carbon was impregnated with sodium bromide to obtain impregnated activated carbon. After spraying the aqueous solution, the plastic container was shaken well to fully adhere NaBr to the activated carbon.

<Evaluation of impregnated activated carbon>
After impregnation, the impregnated activated carbon was sufficiently dried. Thereafter, the BET specific surface area and the removal rate (%) of mercury (Hg ⁰ ) were measured in the same manner as in the above-mentioned "evaluation of activated carbon". Furthermore, 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)
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. Then, each evaluation was performed in the same manner as in Example 1. The results were as shown in Table 1. FIG. 4 shows the results 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 charcoal was used as the carbon material. Then, each evaluation was performed in the same manner as in Example 1. The results were as shown in Table 1.

As shown in Table 1, the impregnated activated carbon of Example 1 has a sufficiently high specific surface area, and therefore has excellent adsorption performance for harmful substances (such as dioxins) 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 removal rate of mercury (Hg ⁰ ) 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 a factor in the low adsorption amount of mercury (Hg ⁰ ). Such impregnated activated carbon is also 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 was discussed below.

The pore size distribution of the carbon 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) ] was sought. For the measurement, a specific surface area/pore analysis measuring device (manufactured by Microtrac Bell Co., Ltd., device name: BELSORP mini II) was used. The results were as shown in Table 2 and FIG. 5. From these results, the integrated value (A) of the differential pore volume [dVp/d(dp)] where the pore diameter is 1 nm or less and the differential pore volume [dVp/d (dp)] where the pore diameter is more than 1 nm and 2 nm or less (dp)] and their ratio (B/A) were determined. These results are as shown in Table 2. In Table 2, the value of B/A is a dimensionless number.

As shown in Table 2 and Figure 5, the carbon material of Comparative Example 2 has a larger proportion of pores with a pore diameter of 1 nm or less than the carbon material of Example 1, but the proportion of pores with a pore diameter of 1 to 2 nm. was confirmed to be small. From this, in the case of activated carbon manufactured using coconut shell charcoal, the impregnated halogen compounds cannot sufficiently penetrate inside the activated carbon particles, and the proportion of halogen compounds impregnated on the surface of the activated carbon becomes high. It is presumed that there are. For this reason, the number of pores that can adsorb mercury (Hg ⁰ ) is limited, and when measuring the removal rate (%) of mercury (Hg ⁰ ), it breaks through early. On the other hand, in the case of the carbon material derived from anthracite and bituminous coal used in Example 1, it 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 inside the activated carbon particles, and that there are sufficient pores to adsorb mercury (Hg ⁰ ) due to the London dispersion force.

Next, Examples 2 to 4 were conducted to investigate the influence of the concentration of the aqueous solution of the halogen compound.

(Examples 2 to 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 each case, the amount of the aqueous solution was set so that the impregnation ratio of NaBr to activated carbon was 3.5% by mass. In the same manner as in Example 1, the impregnated ratio of NaBr and the removal rate (%) of mercury (Hg ⁰ ) of the impregnated activated carbon obtained in each example were measured. The results were as shown in Table 3. Note that 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 amount of mercury (Hg ⁰ ) adsorbed. This is presumed to be due to a decrease in the amount of water molecules adsorbed on the surface of the pores of the activated carbon and to the efficient infiltration of NaBr into the particles of the activated carbon from 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, a part of NaBr did not dissolve at 20°C, so the aqueous solution was heated to about 50°C to dissolve and spray. 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 precipitates and crystallizes when attached to the activated carbon, making it difficult to penetrate into the pores of the activated carbon. In Example 4, the impregnated proportion of NaBr greatly exceeded the target of 3.5% by mass. This is considered to be due to the fact that during the component analysis, a portion where NaBr was crystallized was sampled.

Next, Examples 5 and 6 were conducted in order to investigate the influence of the impregnation 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 onto the activated carbon. In Examples 5 and 6, the impregnation ratio of NaBr was calculated from the mass difference before and after spraying and the concentration of the aqueous solution.

In the same manner as in Example 1, the removal rate (%) of mercury (Hg ⁰ ) of the impregnated activated carbon obtained in Examples 5 and 6 was measured. The results were as shown in Table 4. Note that 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 amount of mercury (Hg ⁰ ) adsorbed decreases. A possible reason for this is that when the halogen elements are too densely packed in the pores of activated carbon, it becomes difficult for mercury (Hg ⁰ ) to penetrate into the pores. Another possible factor is an 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 9 were conducted to investigate the influence of the particle size of the impregnated activated carbon.

(Examples 7 and 8)
Impregnated activated carbon in Examples 7 and 8 was prepared in the same manner as in Examples 5 and 6, except that the amount of NaBr to be sprayed was changed and the impregnated ratio of NaBr to activated carbon was changed. In Examples 7 and 8, the impregnation ratio of NaBr was calculated from the mass difference before and after spraying and the concentration of the aqueous solution. The impregnation ratios of NaBr to activated carbon were 3.5% by mass and 5.0% by mass, respectively. The BET specific surface areas of these impregnated activated carbons were all 1100 m ² /g, and the bulk specific gravity was 480 kg/m ³ . These were formed into pellets to obtain granular impregnated activated carbon having 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 measurements were 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 impregnated activated carbon formed into pellets can also adsorb mercury as well as powdered impregnated activated carbon. Next, we investigated the influence of the type of compound attached.

(Example 9)
<Production of impregnated activated carbon>
Sodium chloride (NaCl) was dissolved in water to obtain an aqueous solution. The NaCl concentration in the aqueous solution was 25.3% by mass. After about 20 g of activated carbon was placed in a plastic container, the above aqueous solution was sprayed onto the activated carbon using a sprayer. The amount of aqueous solution sprayed onto the activated carbon was set so that the impregnation ratio of NaCl to the activated carbon was 4.4% by mass. After spraying the aqueous solution onto the activated carbon, the plastic container was shaken well to sufficiently adhere NaCl to the activated carbon. In this way, 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 measurements were 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. The removal rate (%) of mercury (Hg ⁰ ) for the impregnated activated carbon of Example 1 was also measured under the same conditions as for the impregnated activated carbon of Example 9. The results were as shown in Table 6.

As shown in Table 6, it was confirmed that even if the impregnant was NaCl, it was sufficiently excellent in adsorbing mercury. It was confirmed that as the mercury concentration in the feed gas increases, NaBr becomes more dominant than NaCl.

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

(Example 10)
<Production of impregnated activated carbon>
500 kg of activated carbon produced in the same manner as in Example 1 was placed in a stirring device 50 (ribbon blender) of a 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 for 20 minutes from the nozzle 60A. The droplet diameter was 300-600 μm. The total amount of the NaBr aqueous solution sprayed from the four nozzles 60A was such that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass.

FIG. 6(B) is a diagram of the interior of the stirring device 50 viewed from above, taken along line VIb-VIb in FIG. 6(A). FIG. 6(B) shows an area 64 on the surface of the deposited layer 11 where the spray liquid from each nozzle 60A falls directly when the deposited layer 11 of impregnated activated carbon in the stirring device 50 is viewed from above. There is. The total area of the four areas 64 (spray area) and the ratio of the total area of the areas 64 to the entire surface area of the deposited layer 11 (area ratio) were calculated. These results were as shown in Table 7. In this way, the activated carbon was stirred by the stirring blade 72 while spraying the aqueous solution so that the aqueous solution from the nozzle 60A fell directly onto a part of the surface of the deposited layer 11. In this way, 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 measurements were 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 removal rate (%) of mercury (Hg ⁰ ) for the impregnated activated carbon of Example 1 was also measured under the same conditions as for the impregnated activated carbon of 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 Example 10, except that production equipment equipped with a stirring device 50 (ribbon blender) and a nozzle 60B as shown in FIGS. 7(A) and 7(B) was used. I did it. Since the nozzle 60B of this manufacturing equipment was of a type that sprayed at a wider angle than the nozzle 60A, the number of nozzles was set to two. The droplet diameter was 100-300 μm.

FIG. 7(B) is a diagram of the inside of the stirring device 50 viewed from above, taken along line VIIb-VIIb in FIG. 7(A). 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 on the surface where the spray liquid from each nozzle 60B directly falls. 64 is shown. The total area of the two areas 64 (spray area) and the ratio of the total area of the areas 64 to the entire surface area of the deposited layer 11 (area ratio) 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 such that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass. The results of measuring the removal rate (%) of mercury (Hg ⁰ ) are as shown in Table 8.

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

FIG. 8(B) is a diagram of the inside of the stirring device 50 viewed from above, taken along line VIIIb-VIIIb in 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 areas on the surface where the spray liquid from each nozzle 60B directly falls. 64. The total area of the four areas 64 (spray area) and the ratio of the total area of the areas 64 to the entire surface area of the deposited layer 11 (area ratio) were calculated. Note that although the areas 64 partially overlapped, no particular correction was made for the overlapping portion, and the area of each area 64 was multiplied by 4 to calculate the total area (spray area). These results were as shown in Table 7. The total amount of the NaBr aqueous solution sprayed from the four nozzles 60B was such that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass. The results of measuring the removal rate (%) of mercury (Hg ⁰ ) are as shown in Table 8.

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

Provided is impregnated activated carbon that has 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 that has sufficiently excellent adsorption performance for mercury (Hg ⁰ ).

10, 110, 111... activated carbon, 11... deposited layer, 12... impregnated activated carbon, 20... halogen compound, 22... region, 40... pore, 40A, 40B... micropore, 50... stirring device, 52... introduction part, 54 ...Derivation part, 60, 60A, 60B... Nozzle, 62... Pump, 64... Area, 70... Motor, 72... Stirring blade, 120... Halogen compound, 122... Area, 140... Pore.

On the other hand, in the case of a halogen compound that is a molecule with three or more atoms, the halogen compound 120 is large in size and cannot enter the pores 140 of the activated carbon 110, as shown in FIG . First, it is attached to the surface of activated carbon 110. In this case, the region 122 within the activated carbon 110 that is affected by the London dispersion force becomes small. Therefore, the proportion of pores 140 that can adsorb mercury (Hg ⁰ ) 30 becomes small. Therefore, impregnated activated carbon as shown in FIG. 9( B ) cannot sufficiently adsorb mercury (Hg ⁰ ) 130.

In addition, in the case of activated carbon with few sufficiently small micropores, as shown in FIG . effect on However, since there are few sufficiently small micropores included in the region 122, mercury (Hg ⁰ ) 130 cannot be sufficiently adsorbed.

The contents of the present invention will be explained in more detail with reference to Examples , Reference Examples, and Comparative Examples, but the present invention is not limited to the following Examples.

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.

( Reference example 9)
<Production of impregnated activated carbon>
Sodium chloride (NaCl) was dissolved in water to obtain an aqueous solution. The NaCl concentration in the aqueous solution was 25.3% by mass. After about 20 g of activated carbon was placed in a plastic container, the above aqueous solution was sprayed onto the activated carbon using a sprayer. The amount of aqueous solution sprayed onto the activated carbon was set so that the impregnation ratio of NaCl to the activated carbon was 4.4% by mass. After spraying the aqueous solution onto the activated carbon, the plastic container was shaken well to sufficiently adhere NaCl to the activated carbon. In this way, 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 measurements were 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. The removal rate (%) of mercury (Hg ⁰ ) for the impregnated activated carbon of Example 1 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.

( Reference example 10)
<Production of impregnated activated carbon>
500 kg of activated carbon produced in the same manner as in Example 1 was placed in a stirring device 50 (ribbon blender) of a 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 for 20 minutes from the nozzle 60A. The droplet diameter was 300-600 μm. The total amount of the NaBr aqueous solution sprayed from the four nozzles 60A was such that the impregnation ratio of NaBr to the activated carbon was 3.5% by mass.

<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 measurements were 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 removal rate (%) of mercury (Hg ⁰ ) for the impregnated activated carbon of Example 1 was also measured under the same conditions as for 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 production equipment equipped with a stirring device 50 (ribbon blender) and a nozzle 60B as shown in FIGS. 7(A) and 7(B) was used. I did it. Since the nozzle 60B of this manufacturing equipment was of a type that sprayed at a wider angle than the nozzle 60A, the number of nozzles was set to two. The droplet diameter was 100-300 μm.

Claims (12)

Spraying an aqueous solution of a diatomic halogen compound onto activated carbon obtained by activating a carbon material to impregnate the halogen compound onto the activated carbon,
The method for producing impregnated activated carbon, wherein the carbonaceous material contains coal, and the activated carbon has a carbon content of 70% by mass or more. The method for producing impregnated activated carbon according to claim 1, wherein the carbon content of the carbon material is 70% by mass or more. The method for producing impregnated activated carbon according to claim 1 or 2, wherein the carbon material includes at least one selected from the group consisting of bituminous coal and anthracite coal. The method for producing impregnated activated carbon according to any one of claims 1 to 3, wherein the impregnated ratio of the halogen compound to the 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. A is the integrated value of the differential pore volume [dVp/d (dp)] where the pore diameter is 1 nm or less in the activated carbon, and the differential pore volume [dVp/d (dp)] where the pore diameter is more than 1 nm and 2 nm or less. The method for producing impregnated activated carbon according to any one of claims 1 to 5, which satisfies the following formulas (1) and (2), where B is the integrated value of .
A≧ ^3cm3 /g/nm (1)
B/A≧0.2 (2) The method for producing impregnated activated carbon according to any one of claims 1 to 6, wherein the concentration of the halogen compound in the aqueous solution is 40 to 120 g/100 mL. the halogen compound contains sodium bromide,
The method for producing impregnated activated carbon according to any one of claims 1 to 7, wherein the concentration of the sodium bromide in the aqueous solution is 30 to 42% by mass. The impregnated activated carbon is obtained by using a stirring device that stirs the activated carbon and a nozzle that sprays the aqueous solution, and spraying the aqueous solution onto the activated carbon from the nozzle while stirring the activated carbon with the stirring device. 9. The method for producing impregnated activated carbon according to any one of 1 to 8. comprising activated carbon and sodium bromide impregnated with the activated carbon,
The activated carbon is an activated product of coal and has a carbon content of 70% by mass or more,
Impregnated activated carbon, wherein the ratio of the sodium bromide to the activated carbon is 1.5 to 5% by mass. a stirring device that stirs a deposited layer of activated carbon derived from coal;
an introduction part for introducing the activated carbon having a carbon content of 70% by mass or more into the stirring device;
a nozzle that sprays an aqueous solution of a diatomic halogen compound toward the deposited layer from above the deposited layer;
A production facility for impregnated activated carbon, comprising: a derivation section for deriving the impregnated activated carbon impregnated with the halogen compound from the stirring device. The aqueous solution is sprayed from the nozzle so that the ratio of the spray area of the aqueous solution from the nozzle to the entire surface area of the deposited layer is 40 to 120% when the deposited layer in the stirring device is viewed from above. The impregnated activated carbon production equipment according to claim 11, which sprays an aqueous solution.

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