JPH10314585A - Active carbon catalyst and flue gas denitrification process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flue gas denitrification process of being not inferior to other flue gas denitrification processes in respect of the denitrification efficiency and, therefore, carrying out the flue denitrification process of superior economic efficiency by using an active carbon catalyst for treating pores of desired diameter and providing them with repellency to demonstrate high activities. SOLUTION: An active carbon catalyst is used for adsorbing and oxidizing sulfur oxide and recovering and removing the same by bringing the sulfur oxide into contact with exhaust gas containing the sulfur oxide, and a repellent substance having the diameter equivalent to a ball in the range of 10-100 nm, preferably 10-70 nm is carried on granular active carbon in the range of 0.2-3.0 wt.%, preferably 0.5-1.5 wt.%. to the granular active carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activated carbon catalyst for recovering and removing sulfur oxides contained in exhaust gas as sulfuric acid by a catalytic sulfation reaction, and to a flue gas desulfurization method using the same.

[0002]

2. Description of the Related Art Heretofore, sulfur oxides such as sulfurous acid gas contained in exhaust gas have been oxidized by coexisting oxygen at a low temperature to finally produce sulfuric acid, which can be used as it is as sulfuric acid, or can be combined with calcium compounds. The process of recovering as gypsum by reacting is known.
Activated carbon is considered to be the most preferable as such a catalyst for oxidizing sulfurous acid gas or the like in exhaust gas. That is, when a ceramic-based carrier such as alumina, silica, titania, or zeolite is used as the above catalyst, the activity alone is insufficient, so it is necessary to add a metal or metal oxide as a catalyst species to this. is there.
However, these catalyst species have a drawback that they cannot maintain stable activity for a long period of time because they are attacked by generated sulfuric acid and are dissolved or deteriorated. On the other hand, the activated carbon has a feature that the activity is exhibited without carrying any catalyst species and the activity is maintained without deterioration for a long time.

However, in the case of industrial use as a flue gas desulfurization device, when commercially available activated carbon is used as it is, the catalyst activity is low, so that the catalyst loading is extremely large to obtain a desired desulfurization effect. As a result, there is a problem that compared with other desulfurization processes such as a wet flue gas desulfurization process, it cannot be economically competitive. By the way, the sulfur dioxide adsorption and oxidation activity (hereinafter simply abbreviated as activity) of activated carbon is very large unless the exhaust gas contains moisture. However, the product sulfuric acid has a very high hygroscopicity, so in the presence of water vapor, it absorbs water on the activated carbon surface to generate dilute sulfuric acid, which fills the pores of the activated carbon to form sulfurous acid gas. As a result of impeding the diffusion and contact, the surface activity of the activated carbon is not sufficiently exerted. Therefore, various methods have been proposed for imparting water repellency to activated carbon and quickly discharging the generated sulfuric acid from the pores of the activated carbon to maintain the high activity of the activated carbon.

For example, Chem. Eng. Comm. Vol. 60 (1987),
P253 is sprayed with a dispersion of polytetrafluoroethylene (hereinafter abbreviated as PTFE) on activated carbon having an average diameter of 0.78 mm, thereby adsorbing and oxidizing sulfurous acid gas in a region where the amount of PTFE added is 8 to 20%. An example is disclosed in which the rate constant of the reaction has increased three-fold. Japanese Unexamined Patent Publication (Kokai) No. 59-36531 discloses that a water-repellent treatment is applied to activated carbon to increase the activity of adsorbing and oxidizing sulfurous acid gas. Specifically, a PTFE dispersion liquid is applied to granular activated carbon of 5 to 10 mm. It is disclosed that by impregnating and heat-treating at 200 ° C. for 2 hours, the catalyst exhibits a much higher activity than activated carbon alone.

[0005]

The present inventors conducted the following confirmation experiments in order to verify the effectiveness of such a conventional measure for increasing the activity of activated carbon as a catalyst. First,
2.8 to 4.0 based on the above-mentioned conventional water repellent technology.
PTFE was supported on various types of commercially available activated carbon having a particle size range of mmφ by the spray method or the impregnation method, and the activity was measured. Was observed.
However, considering large-scale industrial practice, this level of activity as a catalyst is still not sufficient to surpass other competing flue gas desulfurization processes, and further improvement in catalytic activity Recognized that it is necessary.

Therefore, the present inventors have examined which portion of the activated carbon is more effective in making the activated carbon water-repellent in order to further enhance the activity of the activated carbon by imparting water repellency. First, the distribution of fluorine in the activated carbon catalyst prepared by the conventional method of spray-supporting or impregnating the PTFE dispersion on activated carbon was analyzed by EPMA. As a result, it was found that the PTFE particles did not penetrate into the activated carbon particles at all, and were all attached to the outer surfaces of the particles. This is because commercially available activated carbon hardly has pores of 1 μm or more, so that the resistance is too large for PTFE particles having a diameter in the range of 0.2 to 0.4 μm to enter the pores. It is thought to be. Incidentally, similar experimental results were obtained when a dispersion of polystyrene particles having an average particle diameter of 0.3 μm was used instead of the PTFE dispersion. When an activity test was performed on the activated carbon catalyst supporting these two types of water-repellent particles, PTFE was obtained.
Was found to be slightly higher in activity than the activated carbon catalyst supporting polystyrene particles, but none of them exhibited the expected high activity.

[0007] The inventors of the present invention hope that the uniform surface of the activated carbon including the vicinity of the active point is made water-repellent to greatly promote the discharge of the produced sulfuric acid. The entire surface including the pores having a pore diameter of (hereinafter abbreviated as micropores) is subjected to a water-repellent treatment. As a first method, 100 to 4
Various activated carbon catalysts having different surface fluorination degrees were prepared by flowing an appropriate amount of fluorine gas at 00 ° C. As a second method, stearic acid, a styrene oligomer (average molecular weight of about 320), a fluorine-containing oil (average molecular weight of about 500) and the like, which are small water-repellent substances, are dissolved in a suitable low-boiling solvent, Activated carbon was immersed under reduced pressure, the solution was sufficiently penetrated into the pores, and then dried under reduced pressure to evaporate the solvent, thereby coating the inside of the activated carbon pores with a water-repellent substance. The specific surface area of the activated carbon catalyst prepared in this manner is within an apparent decrease range due to an increase in weight due to the support of the water-repellent substance, and these supports may block or destroy the pores. Not confirmed.

[0008] Next, 1 to 4 obtained by the first method
A sulfur dioxide gas reaction activity test was carried out using various activated carbon catalysts having a fluorination rate of 20 wt%. As the fluorination rate increased, the water repelling property gradually increased. Time test (this is a simple method for relative comparison of water repellency, in which the activated carbon particles subjected to water repellency treatment are gently floated on the water surface, and the average value of the sedimentation start time and sedimentation end time is calculated.) However, it was found that the sulfurous acid gas adsorption and oxidation activities decreased in inverse proportion to the increase in the fluorination rate. Also,
In the activated carbon catalyst supporting stearic acid, styrene oligomer, fluorinated oil, and the like obtained by the second method, the water repellency was similarly measured by the water surface floating time test as the supported amount increased. Although the increase is observed, the sulfuric acid gas adsorption and oxidation activity are 0.5 to
It was found that in the 2% addition region, the activity slightly increased only slightly over the catalytic activity of the activated carbon alone, and the activity rapidly decreased with an increase in the added amount.

From the above, it is presumed that the full water repellency of activated carbon, including the micropores, covers or destroys active sites for adsorption and oxidation of activated carbon, so that it is not possible to obtain a sufficient activity improving effect. did. Therefore, the present inventors have found that micropores, which are considered to most contribute to the activity of activated carbon, do not become water-repellent, but repel only macropores (pores having a pore diameter of more than 5 nm) which serve as a discharge channel for generated sulfuric acid. Tried to hydrate. First, a polyethylene or polystyrene powder having a molecular weight of 100,000 or more is dissolved in toluene heated to 60 to 70 ° C. by several percent, and activated carbon particles are immersed under reduced pressure. Scattered. The activated carbon catalyst thus obtained has a water-repellent substance of 0.3 to
In the 1.5 wt% loading range, the activity was significantly improved.

[0010] If polyethylene and polystyrene having a molecular weight of 100,000 or more are supposed to be spherical and dispersed in a toluene solvent, their diameter becomes 7 nm or more even if they do not swell in the solvent. It is not a size that can penetrate the micropore. Therefore, it should be considered that the activated carbon catalyst makes the macropores and the outer surface of the activated carbon particles water-repellent. And, as mentioned above,
In this reaction system, the water repellency of the outer surface of the activated carbon does not contribute much to the improvement of the reaction activity, so that the water repellency of the macropores of the activated carbon contributes most to the improvement of the activity. Is inferred.

[0011] Then, in order to obtain the knowledge that the degree of pore repellency of the macropores in the raw material activated carbon contributes most to the improvement of the activity, each polystyrene (hereinafter, referred to as PS) was used. 5 types of latexes (average particle diameters of 10, 28, 55, 102, and 300 nm) (PS spherical particles having a relatively uniform size of about 10 wt% dispersed in water) are prepared. These were all diluted to 0.1 to 5% by weight, and each of them was immersed in a raw material activated carbon under reduced pressure, and then dried under reduced pressure to prepare an activated carbon catalyst, which was subjected to an activity test. As a result, in any of the activated carbon catalysts, the optimum addition amount of PS exhibiting the highest activity is around 1 wt%, those with average diameters of 28 nm and 55 nm show high activity, and those with 10 nm and 102 nm show high activity. It was found that the activity was slightly lower than that, and that the average diameter of 300 nm was not much different from the untreated activated carbon in the activity. SEM observation of catalyst particle fracture surfaces of these five types of activated carbon catalysts revealed that the average diameter of PS was 55 nm or less.
The particles uniformly penetrate into the inside of the activated carbon particles, whereas the 102 nm PS particles are abundant near the surface of the activated carbon particles, and the 300 nm PS particles are located only on the outer surface of the activated carbon particles. Had adhered.

The reason why the activated carbon catalyst impregnated with PS particles having an average diameter of 10 nm is lower in activity than those impregnated with PS particles of 55 nm and 102 nm does not fall within the estimated range, but the PS particles have a small diameter. This is considered to be due to the fact that the micropores of the raw material activated carbon are more likely to be clogged. Therefore, from the above experimental results, the average diameter is 28n.
This indicates that it is necessary to make all the macropores having a diameter not less than the minimum diameter into which the m PS particles can penetrate water-repellent.
To confirm this, a PTFE dispersion having an average particle diameter of 30 nm was obtained in place of the PS particles,
Activated carbon was impregnated in the same manner as S latex to prepare an activated carbon catalyst. An activity test was also performed on this activated carbon catalyst. As a result, the activated carbon catalyst showed an activity not inferior to that of the activated carbon catalyst loaded with PS particles having an average particle diameter of 28 nm.

[0013] The above activity test confirmed that making the macropores water repellent greatly contributed to the improvement of the activity. At the same time, the following findings were obtained in an experiment using the PS particles. That is, it is a finding that considerably higher activity can be obtained by impregnating PS in the form of a spherical PS of 10 to 100 nm than by melting PS in an organic solvent or the like and impregnating the pores. This is because, while the PS carried by the former method is carried in a planar shape, the PS carried by the latter method has an uneven surface.
It is presumed that a film is formed, and as a result, the apparent contact angle with the liquid increases. In this way,
It was possible to obtain an activated carbon catalyst having high activity, which was initially targeted, and completed the present invention.

The present invention has been made on the basis of the above findings, and an activated carbon catalyst capable of exhibiting high activity by allowing water-repellent treatment of pores having a desired diameter, and the use of the activated carbon catalyst. It is another object of the present invention to provide a flue gas desulfurization method that is comparable in desulfurization efficiency as compared with other flue gas desulfurization processes, and is thus capable of performing flue gas desulfurization with excellent economic efficiency.

[0015]

According to the first aspect of the present invention, an activated carbon catalyst according to the present invention is brought into contact with an exhaust gas containing a sulfur oxide to adsorb and oxidize the sulfur oxide to recover and remove the sulfur oxide as sulfuric acid. Activated carbon catalyst for supporting a water-repellent substance having a sphere equivalent diameter of 10 to 100 nm on granular activated carbon in an amount of 0.2 to 3.0 wt% based on the activated carbon. is there. Here, in the invention according to claim 2, the sphere equivalent diameter of the water-repellent substance is 1
It is characterized in that it is in the range of 0 to 70 nm, and the invention according to claim 3 is characterized in that the water-repellent substance is
It is characterized in that 0.5 to 1.5 wt% is supported on the activated carbon.

The invention described in claim 4 is the first invention.
3. The water-repellent substance according to any one of Items 1 to 3, wherein the water-repellent substance is polyethylene, polystyrene, polypropylene, polytetrafluoroethylene, perfluoroalkoxy resin, tetrafluoroethylene hexafluoropropylene copolymer, or trifluoroethylene chloride resin. It is assumed that. And Claim 5
In the flue gas desulfurization method according to the present invention described in the above, by contacting the activated carbon catalyst according to any one of claims 1 to 4 with an exhaust gas containing a sulfur oxide, the sulfur oxide in the exhaust gas It is characterized in that it is adsorbed and oxidized on an activated carbon catalyst and recovered and removed as sulfuric acid.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of an activated carbon catalyst according to the present invention will be specifically described. The activated carbon catalyst according to the present invention is for oxidizing sulfurous acid gas in exhaust gas by coexisting oxygen to recover and remove it as sulfuric acid.The macropores excluding micropores that contribute to the activity of the granular activated carbon are subjected to water repellent treatment. The main feature is that it has been done. Here, as the activated carbon to be used, various commercially available activated carbons can be applied, and the particle size thereof should be appropriately selected depending on the type of a filling tank filled with the activated carbon catalyst. By the way, in the case of a general filling tank, the smaller the particle size, the higher the activity.
It is preferable to adopt a thickness of 0 mm, preferably 3 to 6 mm. As other shapes, various shapes such as a plate shape and a honeycomb shape can be freely selected.

The first important point that has a great effect on the improvement of the activity by making the activated carbon water-repellent is that it is in a specific diameter range in order to make the macropores excluding the micropores that greatly contribute to the activity of the activated carbon water-repellent. The point is that the activated carbon is impregnated with particles of a water repellent substance. The particles of the water-repellent substance are usually spherical, but may have a shape other than spherical. The average diameter of the particles of the water-repellent substance (the average value of the equivalent sphere diameter in a shape other than a sphere) is 10
It is necessary that the thickness be in the range of 10 to 70 nm, and more preferably in the range of 10 to 70 nm. As a technique applicable for controlling and preparing the particle size of such water-repellent substance particles, for example, there is a technique for producing a medical latex. This is known as a technique for making the particle size of the dispersion system uniform during the emulsion polymerization of PS, and the production of spherical particles of 28 nm or more is an easy technique for a skilled person skilled in the art, and the production of spherical particles of 10 nm Manufacturing is also possible. Usually, the particle size distribution of latex particles obtained by the above technique is extremely sharp, and if 95% or more of the particles has an average particle diameter of γ, it falls within γ ± 0.1γ. Another example is a technique using a commercially available PTFE dispersion. In this case, the commercially available PTFE dispersion contains PTFE particles having an average particle size of 0.3 μm, and the average particle size can be adjusted to 20 to 30 μm by appropriately adjusting the emulsification conditions.
It can be freely prepared in the range of 400 nm.

An important point is that the amount of the particles of the water-repellent substance carried on the activated carbon has an optimum range. That is, if the amount is too large, the surface of the activated carbon will be coated with the water-repellent substance over a plurality of layers, and as a result, particles of the extra water-repellent substance will narrow the macropores serving as a discharge path for the generated sulfuric acid. This is because or, or block the activation to inhibit the activation, on the other hand, if the supported amount is too small, the originally intended effect of water repellency, that is, the sufficient effect of discharging the generated sulfuric acid will not be obtained, Both are inappropriate. According to the findings of the present inventors,
Although the optimum value of the supported amount slightly varies depending on the particle size of the water-repellent substance, the optimum range is usually 0.2 to 3 wt%, preferably 0.5 to 1.5 wt%.

As a preferable method for impregnating the activated carbon with such a water-repellent substance, for example, a method of dispersing the activated carbon and the water-repellent substance to such an extent that the activated carbon is substantially immersed in a container such as a rotary evaporator which is easy to operate. There is a method in which a liquid and a water-repellent substance are supported on activated carbon while a solvent (water in this case) is blown off under reduced pressure. At this time, after the water evaporates, it is dried at a temperature lower than the melting point of the water-repellent substance, usually at 60 ° C. or lower for 3 to 12 hours. Incidentally, after impregnating the particle dispersion of the water-repellent substance under reduced pressure, there is also a method of directly putting this in a box-shaped dryer, but in the method, compared with a method using a rotary evaporator, It is not preferable because the loading may be uneven.

Next, as the above-mentioned water-repellent substance in the present invention, in addition to the above-mentioned PS and PTFE, the following various water-repellent substances can be applied. Here, the water-repellent substance has a contact angle of 90 ° or more with water, has such water repellency, and has an average diameter of 10 to 10 as described above.
Particles of 0 nm, preferably 10 to 70 nm, can be used as long as they are stable in water or sulfuric acid solution. As the water-repellent substance satisfying these requirements, there is generally a hydrocarbon-based resin or a fluorine resin. Specifically, as the hydrocarbon resin, polystyrene, polypropylene, and the like are preferable in addition to PS, which has already been exemplified. Further, as the above-mentioned fluorine resin, a commercially available resin can be used, but it is preferable to select a resin having a high fluorine content, that is, a resin having excellent water repellency. Examples of such a fluorine resin include the above P
In addition to TFE, perfluoroalkoxy resin (PF
A) Tetrafluoroethylene 6-propylene copolymer (FE)
P) or trifluoroethylene chloride resin (PCTEF) is preferred.

Using the activated carbon catalyst prepared as described above, an exhaust gas containing sulfur oxide is brought into contact with the activated carbon catalyst,
By adsorbing and oxidizing the sulfur oxides in the exhaust gas on the activated carbon catalyst and recovering the sulfur oxides as sulfuric acid, there is no inferiority in desulfurization efficiency as compared with other flue gas desulfurization processes, and thus the flue gas desulfurization is excellent in economy. Can be performed.

[0023]

Next, the present invention will be described more specifically with reference to examples according to the present invention in which granular activated carbon carries spherical PS and spherical PTFE. (Example 1) Six types of commercially available activated carbons (AF)
Were fired in a nitrogen stream at 800 ° C. for 1 hour.
Hereinafter, this is referred to as a spherical polystyrene unsupported catalyst. Next, deionized water was added to an aqueous dispersion (10 wt%) of a commercially available spherical polystyrene having an average particle diameter of 28 nm to dilute it 50-fold, and 20 g of each unsupported polystyrene catalyst was immersed in 100 cc of the spherical polystyrene dispersion. After drying under reduced pressure with a rotary evaporator, this was dried in a dryer at 45 to 50 ° C. for 12 hours. Next, the amount of polystyrene supported on the obtained activated carbon catalyst was determined from the difference between the dry weights of the activated carbon before and after the loading, and the amount of spherical polystyrene supported was about 1 wt%.

Next, the activated carbon catalyst (average particle size 28 nm, supported amount: about 1 wt%) thus prepared and a catalyst not supported on spherical polystyrene for comparison were subjected to an activity test using a contact sulfation reaction test apparatus. did. 40 ml of each catalyst was charged into a jacketed glass reactor having an inner diameter of 16 mmφ, SO ₂ ; 1000 vol ppm, O ₂ ; 4 vol%, CO 2
₂ ; 10 vol%, N ₂ ; balance, and a relative humidity of 100% gas were passed through this reactor at 50 ° C. and 200 dm ³ / hr (SV = 5000 hr ⁻¹ ), and a SO ₂ meter (ultraviolet / infrared) was used. formula)
The SO ₂ concentration at the outlet was measured to evaluate the catalytic activity. FIG. 1 shows the desulfurization performance of each catalyst 100 hours after the start of the test. From FIG. 1, it can be seen that the desulfurization performance of each of the catalysts in which about 1 wt% of spherical polystyrene having an average particle diameter of 28 nm was supported on six types of activated carbon was significantly improved as compared to the catalyst not supporting spherical polystyrene.

(Example 2) Activated carbon A similar to that in Example 1
Was fired at 800 ° C. for 1 hour in a nitrogen stream. Next, commercially available spherical polystyrene (having an average particle diameter of 10, 28, 5
5, 102, 305 nm total 5 types) aqueous dispersion (10
wt%) and diluted with deionized water to obtain various concentrations (0 to 0%).
5% by weight), and 20 g of the activated carbon was immersed in 100 cc of the spherical polystyrene dispersions having different concentrations, and dried with a rotary evaporator under reduced pressure. Then 45-
Drying was performed in a dryer at 50 ° C. for 12 hours to prepare various catalysts having different average particle diameters and supported amounts of spherical polystyrene.

The activated carbon catalyst and the spherical polystyrene supported catalyst thus prepared were subjected to an activity test using the reaction test apparatus described in Example 1 under the same conditions to evaluate the catalytic activity. FIG. 2 shows the desulfurization performance of each catalyst 100 hours after the start of the test. FIG. 3 shows, based on the results of FIG. It shows the effect. First, as can be seen from FIG. 2, the activated carbon catalyst loaded with spherical polystyrene having an average particle diameter of 102 nm or less showed high desulfurization performance, and the desulfurization performance was greatly improved as compared with the catalyst not loaded with spherical polystyrene. It was also found that the optimal amount of spherical polystyrene was about 0.2 to 3% by weight. Further, from FIG. 3, the optimal diameter of the spherical polystyrene to be supported is 5 to 100 nm (preferably, 10 to 100 nm).
70 nm).

Example 3 Activated carbon A similar to that of Example 1
Was fired at 800 ° C. for 1 hour in a nitrogen stream. Next, two types of commercially available spherical PTs having average particle diameters of 50 and 300 nm were used.
Dilute the FE dispersion (60 wt%) by adding deionized water,
20 g of the above activated carbon was added to each spherical PTFE dispersion 100 cc.
And dried under reduced pressure with a rotary evaporator.
Thereafter, drying was performed in a dryer at 45 to 50 ° C. for 12 hours to prepare an activated carbon catalyst having a spherical PTFE support amount of 1 wt% and different average particle diameters. Next, the obtained activated carbon catalyst was subjected to an activity test using the reaction test apparatus described in Example 1 under the same conditions to evaluate the catalyst activity. FIG.
Shows the desulfurization performance of the activated carbon catalyst 100 hours after the start of the test. From FIG. 3, it can be seen that spherical PTFE exhibits the same behavior as spherical polystyrene, but when compared with the same particle size and the same amount of support, supporting spherical PTFE exhibits higher desulfurization performance.

Comparative Example 1 Further, in order to confirm the difference between spherical polystyrene and dissolved polystyrene as the water-repellent substance carried on activated carbon, the same activated carbon A was fired at 800 ° C. for 1 hour in a nitrogen stream. Together with commercially available polystyrene (0, 0.15, 0.3, 0.6, 1, 1.5
g) about 100 cc of toluene each heated to 50-70 ° C
Were prepared, solutions having different polystyrene concentrations were prepared, and 50 g of the activated carbon were immersed in the polystyrene solutions having different concentrations, and impregnated with a rotary evaporator under reduced pressure and dried. Thereafter, drying was similarly performed under reduced pressure in a dryer at 45 to 50 ° C. for 12 hours to prepare various catalysts (0 to 3 wt%) having different polystyrene loading amounts. Hereinafter, this catalyst is referred to as a dissolved polystyrene supported catalyst. Next, the obtained dissolved polystyrene-supported catalyst and the activated carbon catalyst prepared in Example 2 were subjected to an activity test under the same conditions using the reaction test apparatus described in Example 1 to evaluate the catalytic activity. FIG. 4 shows the desulfurization performance of each catalyst 100 hours after the start of the test. As shown in the figure, the spherical polystyrene-supported catalyst exhibited higher desulfurization performance than the dissolved polystyrene-supported catalyst in the range of the same supported amount of 0.2 to 3 wt%.

[0029]

As described above, in the activated carbon catalyst according to any one of claims 1 to 4, the granular activated carbon is
By supporting a water-repellent substance having a sphere equivalent diameter in the range of 10 to 100 nm, preferably 10 to 70 nm, based on the granular activated carbon in an amount of 0.2 to 3.0 wt%, preferably 0.5 to 1.5 wt%. With the exception of the micropores that contribute to the most catalytic sulfation reaction of the activated carbon, it is possible to obtain a highly active activated carbon catalyst in which macropores serving as flow paths for the generated sulfuric acid are efficiently water-repellent. it can. Therefore, according to the flue gas desulfurization method according to claim 5 using the activated carbon catalyst according to any one of claims 1 to 4, there is no inferiority in desulfurization efficiency as compared with other flue gas desulfurization processes, and thus economical Exhaust gas desulfurization with excellent performance is enabled.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of an activity test in Example 1 of the present invention.

FIG. 2 is a graph showing the results of an activity test of Example 2.

FIG. 3 is a graph showing the results of an activity test of Example 3 (2).

FIG. 4 is a graph showing the results of an activity test of Example 4.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Iwa ▲ saki ▼ Mamoru 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (72) Inventor Osamu Togawa, Yokohama-shi, Kanagawa 2-1-1, Tsurumi-Chuo, Tsurumi-ku Chiyoda Chemical Works, Ltd. (72) Inventor Takashi Kimura 2-1-1, Tsurumi-Chuo 2-chome, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Chiyoda Chemical Works, Ltd.

Claims (5)

[Claims] An activated carbon catalyst for adsorbing and oxidizing the sulfur oxide by contacting with an exhaust gas containing the sulfur oxide to recover and remove the sulfur oxide as sulfuric acid. An activated carbon catalyst comprising a water-repellent substance having a diameter of 0.2 to 3.0% by weight based on the activated carbon. 2. The sphere equivalent diameter of the water-repellent substance is 10 to 10.
2. The activated carbon catalyst according to claim 1, wherein the range is 70 nm. 3. The method according to claim 1, wherein the water-repellent substance is supported in an amount of 0.5 to 1.5% by weight based on the activated carbon.
Or the activated carbon catalyst according to 2. 4. The water-repellent substance is polyethylene, polystyrene, polypropylene, polytetrafluoroethylene, perfluoroalkoxy resin, tetrafluoroethylene hexafluoropropylene copolymer, or trifluoroethylene chloride resin. The activated carbon catalyst according to any one of claims 1 to 3, characterized in that: 5. An activated carbon catalyst according to claim 1, which is brought into contact with an exhaust gas containing a sulfur oxide to adsorb and oxidize the sulfur oxide in the exhaust gas on the activated carbon catalyst. A flue gas desulfurization method comprising collecting and removing sulfuric acid.