TWI436825B - Carbon catalyst for exhaust gas desulfurization and its manufacturing method and use for enhancing mercury in exhaust gas - Google Patents

Description

Carbon-based catalyst for flue gas desulfurization and its manufacturing method and use for removing mercury in exhaust gas

The present invention relates to a carbon-based catalyst for flue gas desulfurization which is obtained by removing a sulfur oxide contained in exhaust gas as a sulfuric acid by a contact sulfation reaction, and a method for producing the carbon-based catalyst.

Further, the present invention relates to a mercury-sucking treatment mercury adsorption material which adsorbs and removes mercury contained in exhaust gas, particularly metal mercury, and a smoke evacuation treatment method using the mercury adsorption material.

In general, the method of removing the sulfurous acid gas (SO ₂ ) contained in the exhaust gas has a wet method in which the absorption liquid is absorbed and removed, and a dry method in which the adsorption material is removed and removed. When the concentration of sulfuric acid gas is treated as a large amount of exhaust gas, the wet method is widely used. When the concentration is relatively low or a small amount of exhaust gas is treated, the structure is simple and easy to maintain. The dry method.

According to the exhaust gas treatment method of the dry method, it is known that the sulfur oxides such as sulfurous acid gas contained in the exhaust gas are oxidized by oxygen coexisting at a low temperature, and finally recovered as sulfuric acid. The flue gas desulfurization process (contact sulfation reaction). When a ceramic-based support such as alumina, ceria, titania or zeolite is used as a catalyst for oxidizing sulfite gas or the like in the exhaust gas, if only the support is used, the activity is insufficient, so A metal or metal oxide is added as a catalyst material. Also, since these catalyst substances are activated or catalyzed by the generated sulfuric acid, they dissolve or deteriorate. Therefore, it has the disadvantage that it cannot maintain the stability of stability for a long time. Therefore, activated carbon which is excellent in acid resistance and which maintains stability characteristics without deteriorating for a long period of time is extremely suitable as the above-mentioned catalyst.

However, if commercially available activated carbon is directly used as the above-mentioned catalyst, the catalytic activity of the contact sulfation reaction is low, and the generated sulfuric acid cannot be smoothly discharged, and as a result, in order to obtain a desired desulfurization effect, not only It is necessary to increase the amount of catalyst to be filled, and it is necessary to carry out regenerative treatment on a regular basis, which has a problem of economical disadvantage.

For example, in Japanese Laid-Open Patent Publication No. 2005-288380, it is proposed to adjust the gas to be treated to a living carbon-containing honeycomb body by contacting the activated carbon honeycomb body with a relative humidity of more than 100%. The active carbon-containing honeycomb system supporting the drug holds a drug such as iodine, bromine, acid, or platinum metal compound which can significantly improve the treatment efficiency, thereby allowing the odor component and the air pollution component in the gas to be used for a long time. A gas treatment method that repeats the treatment.

According to the gas treatment method described above, by adjusting the relative humidity of the gas to be supersaturated to a supersaturated state, that is, more than 100%, it can be uniformly produced on the surface of the active carbon-containing honeycomb body in contact with the active carbon-containing honeycomb body. The film of water causes the odor component and the air pollution component to oxidize on the surface of the activated carbon-containing honeycomb body to form a compound dissolved in water, and the water-soluble reaction product passes through the surface of the activated carbon-containing honeycomb body through the water. The film is gradually dissolved and detached from the active carbon-containing honeycomb body, whereby the activated carbon-containing honeycomb body is self-regenerated, and the treatment life can be greatly extended.

However, in the above gas treatment method, it is necessary to additionally treat the gas to be treated. The body is sprayed or sprayed with water or an aqueous solution, or the treated gas is flushed into the air bubbles in an aqueous solution, and a humidifying device or the like is used to humidify the gas to be treated to a relative humidity of more than 100%, thereby having a gas treatment facility. The problem of increased energy consumption.

In addition, if the humidity is more than 100% relative humidity, the film is uniformly produced on the surface of the activated carbon honeycomb body, which may hinder the direct contact between the gas to be treated and the active carbon-containing honeycomb body, thereby making the activity active. The catalytic performance of carbon is more difficult to exert, and it is necessary to increase the amount of active carbon-containing honeycomb body in order to obtain a desired desulfurization effect.

Furthermore, as described in the literature, it is possible to repeat the treatment of the activated carbon-containing honeycomb body which causes the treatment performance to be degraded by using water for a long period of time, that is, the activated carbon-containing honeycomb body itself must be fixed at a certain time. The time is based on the problem of regeneration treatment of sprinkling water, so the development of highly active catalysts is still expected.

On the other hand, there are still other requirements for the requirements of catalysts with high desulfurization activity.

That is, the combustion exhaust gas discharged from a boiler of a thermal power plant generally contains a high concentration of mercury in addition to the sulfuric acid gas, depending on the type of fossil fuel (especially coal) that is burned. . Since mercury is a harmful substance that causes health hazards if it is discharged into the environment, it must be removed before it is discharged to the atmosphere. Therefore, in recent years, in addition to sulfurous acid gas, regulations for removing mercury have also been implemented.

The mercury in the exhaust gas has Hg ²⁺ in the form of a divalent mercury compound due to oxidation of an oxidation catalyst in a combustion furnace or a flue gas denitration device, and a form of a monomer (zero-valent) metal mercury. The existence of Hg ⁽⁰⁾ , Hg ²⁺ can be almost completely removed in the wet flue gas desulfurization device, but since Hg ⁽⁰⁾ has a small solubility to the absorption liquid, the removal efficiency is low, so most of the current It is discharged to the atmosphere without being removed.

Therefore, it has been proposed to add a halogen compound such as hydrogen chloride or calcium bromide to the exhaust gas or coal as a fuel, or to oxidize Hg ⁽⁰⁾ in the exhaust gas to Hg by using an oxidation catalyst of a denitration device. Method of ²⁺ (Japanese Laid-Open Patent Publication No. 2004-66229). However, due to the problem of the lifetime of the catalyst, or the diffusion of Hg ⁽⁰⁾ in the exhaust gas is restricted and it is difficult to achieve a high oxidation rate, it is difficult to oxidize Hg ⁽⁰⁾ to Hg2 ⁺ with high efficiency over a long period of time. .

Further, a method of adding a Hg immobilizing agent such as a chelating agent or a potassium iodide (KI) solution or an oxidizing agent such as hypochlorous acid or hydrogen peroxide to an absorbent of a wet flue gas desulfurization device has been proposed ( Japanese Patent Laid-Open No. Hei 10-216476). However, the Hg-immobilizing agent or oxidizing agent may be decomposed by reaction with other metals, or may be oxidized by SO ₂ in the exhaust gas, or may be volatilized and discharged from the chimney, so the input amount of these additives may increase. The problem. When a chelating agent is added, decomposition occurs to form hydrogen sulfide (H ₂ S), so that it also has a problem of generating malodor.

In the method of adding various additives to the absorbing liquid, when the state of the absorbing liquid changes due to fluctuations in the power generation load or changes in the composition of the exhaust gas, it is known that once absorbed by the absorbing liquid, Hg ⁽⁰⁾ is again It is released, or Hg ²⁺ in the absorbing liquid is reduced to Hg ⁽⁰⁾ and released again. Therefore, the development of technology that will not release Hg ⁽⁰⁾ is actively carried out (Japan Special Open 2004). -313833). Further, in the method of using an oxidizing agent such as hypochlorous acid, hydrogen peroxide, chromic acid or chlorine, the reaction between the oxidizing agent and the SO ₂ in the exhaust gas cannot be avoided, and the amount of the oxidizing agent is excessively lost. A method of spraying these oxidizing agents to the downstream side of the flue gas desulfurization apparatus has been proposed (JP-A-2001-162135).

On the other hand, regarding the absorption liquid which is not absorbed in the wet flue gas desulfurization apparatus, the method of removing Hg ⁽⁰⁾ by other methods is known, and a gas region having a temperature of around 100 to 150 ° C is known. A method in which activated carbon powder is added to an exhaust gas to be dispersed, and Hg ^{(0) is} adsorbed to the activated carbon powder and removed (Japanese Patent Laid-Open Publication No. Hei 9-308817). In addition, it is known that it is effective to remove the activated carbon such as the bromide, and it is known to be effective in the removal of the mercury (Japanese Unexamined Patent Publication No. SHO-49-53590 and JP-A-43-53591). However, the mercury adsorption capacity of activated carbon is generally small, and uniform contact is considered. If the amount of addition to the exhaust gas is small, the effect cannot be improved. Therefore, it is necessary to add a large amount to the exhaust gas on the downstream side. The activated carbon is trapped together with the fly ash, so a large-scale electric dust collector is required, and a device for treating the activated carbon trapped in the state mixed with the fly ash is also required. In addition, these methods are carried out on the upstream side of the wet flue gas desulfurization device, or in combination with a dry or semi-dry flue gas desulfurization device, which is used to remove a gas having a certain high concentration. Mercury is not used to remove the lower concentration of mercury contained in the outlet gas of the wet flue gas desulfurization unit.

On the other hand, it has been proposed to support the active carbon such as iodine, and the outlet gas of the wet flue gas desulfurization device, and in detail, desulfurization with wet flue gas. A method of removing the mercury in the gas by contacting the outlet gas of the wet electric dust collector provided on the downstream side of the apparatus (Japanese Patent Laid-Open No. Hei 10-216476). In particular, in this method, since the wet electric dust collector is provided on the upstream side of the mercury removing device, although it is the outlet gas of the wet flue gas desulfurizing device, there is no mist in the gas. In addition, the temperature was raised to 77 ° C or higher using a gas reheater. That is, by increasing the temperature to lower the relative humidity, a condition substantially close to the upstream side of the wet flue gas desulfurization apparatus is produced, and then the treatment according to the iodine-supporting activated carbon is performed.

As described above, the conventional method of absorbing the mercury in the exhaust gas by the absorption liquid of the wet flue gas desulfurization apparatus has a problem that the high mercury removal rate cannot be maintained stably for a long period of time. In addition, the oxidizing agent used to oxidize mercury is consumed by the oxidation of sulfurous acid, or the chelating agent for trapping mercury reacts with other metals to increase the loss, and the added oxidizing agent cannot be effectively used. Or a chelating agent, the oxidation of mercury is insufficient, and there is a problem that Hg ⁽⁰⁾ is released again from the absorption liquid.

On the other hand, in the method of dispersing the activated carbon powder in the exhaust gas and adsorbing and removing the mercury, as described above, since the mercury adsorption capacity of the activated carbon is small, the amount of addition is increased, and the amount of post-treatment is also included. , the cost is more unfavorable. In addition, when the concentration of water or sulfurous acid gas in the exhaust gas is high, the mercury adsorption capacity of the activated carbon is remarkably lowered, and even if the activated carbon holding a halogen compound such as bromide is used, sufficient adsorption cannot be exhibited. Capacity, therefore, when used in combination with a wet flue gas desulfurization device, if it is treated on the upstream side, it is greatly affected by sulfurous acid gas. When the downstream side is treated, it is greatly affected by moisture, and no matter which side is treated, the difficulty of greatly reducing the adsorption capacity of activated carbon cannot be avoided. Therefore, according to the adsorption treatment of activated carbon, more is used in combination with dry flue gas desulfurization, and combined with wet flue gas desulfurization with high desulfurization efficiency, especially on the downstream side of the wet flue gas desulfurization device. Users are generally not considered.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a catalyst capable of continuously maintaining stable desulfurization performance for a long period of time, and having high activity and capable of greatly reducing a catalyst required for exhaust gas treatment. A carbon-based catalyst for exhausting flue gas desulfurization and a method for producing a carbon-based catalyst for desulfurization of the flue gas.

Further, another object of the present invention is to provide an efficient evacuation of exhaust gas even when the exhaust gas containing high humidity of moisture or mist is treated on the downstream side of the wet flue gas desulfurization apparatus. The mercury-containing mercury-absorbing material for adsorbing and removing the metal mercury is removed and the smoke-treating method using the mercury adsorbing material.

In order to achieve the above object, according to the present invention, a carbon-based catalyst is provided which reacts with the above-mentioned oxygen and water vapor by contacting with an exhaust gas containing at least sulfurous acid gas, oxygen, and water vapor. Sulfuric acid, and recovering the carbon-based catalyst for flue gas desulfurization of the sulfuric acid, characterized in that iodine, bromine or a compound thereof is impregnated on the surface of the carbon-based catalyst to form ion exchange or support, and water is dispensed Processed.

The above carbon-based catalyst is preferably activated carbon or activated carbon fiber. In addition, The compound of the above iodine or bromine is preferably any of an alkali metal salt of iodine or bromine, a metal salt of an alkaline earth, a transition metal salt, a hydride, an oxo acid, and an organic compound.

The immersion, ion exchange or support amount of the above iodine or a compound thereof to the carbon-based catalyst is preferably in the range of 0.020% by weight or more and 60% by weight or less based on the desired iodine. Further, the amount of immersion, ion exchange or support of the bromine or the compound thereof to the carbon-based catalyst is preferably in the range of 0.010% by weight or more and 60% by weight or less.

In the water repellency treatment, it is preferred that the carbon-based catalyst contains a resin having a contact angle with water of 90 degrees or more, or a heat treatment is performed on the carbon-based catalyst to remove a hydrophilic group on the surface. .

In the carbon-based catalyst for flue gas desulfurization according to the present invention, iodine, bromine or a compound thereof is impregnated to form ion exchange or support on the surface of the carbon-based catalyst. Therefore, when the exhaust gas containing at least sulfurous acid gas, oxygen, and water vapor is contacted, when the carbon-based catalyst is represented by, for example, iodine, the following reaction occurs.

4I ^- +4H ⁺ +O ₂ → 2I ₂ +2H ₂ O (Formula 1)

I ₂ +SO ₃ ^2- +H ₂ O → 2I ^- +H ₂ SO ₄ (Formula 2)

Thereby, the iodine function on the above carbon-based catalyst acts as a catalyst auxiliary agent, and the desulfurization performance is improved. In addition, since the carbon-based catalyst is subjected to the water-repellent treatment, the sulfuric acid produced in the above formula 2 can be continuously and smoothly discharged from the carbon-based catalyst, and the regeneration treatment such as watering can be performed without For a long time Continue to maintain stable desulfurization performance.

That is, in the above-mentioned Japanese Patent Publication No. 2005-288380, it is important to uniformly produce a film of water on the surface of the catalyst, and thus to adjust the relative humidity in the exhaust gas to more than 100%, as opposed to Therefore, in the catalyst of the present invention, since the water repellency treatment is applied, a film of water is not uniformly formed on the surface of the catalyst, and a dried portion is generated on the surface of the carbon-based catalyst. Thereby, the sulfurous acid gas in the exhaust gas can be directly contacted with the carbon-based catalyst without passing through the film of water, whereby the reaction can be promoted, and the generated sulfuric acid aqueous solution can be smoothly fused, and the catalyst is used. Naturally detached.

Further, in the dried portion of the above carbon-based catalyst, iodine or bromine may exhibit a large effect, so that high desulfurization performance can be obtained, and even if the relative humidity in the exhaust gas does not exceed 100%, It is also possible to obtain desulfurization performance which is extremely high and which does not deteriorate due to passage of time. As a result of the above-mentioned Japanese Patent Publication No. 2005-288380, since the generated sulfuric acid is accumulated in the catalyst, when the use of the sulfuric acid for a long period of time causes a decrease in the process performance, it is necessary to repeat the regeneration treatment by sprinkling water to remove the sulfuric acid. On the other hand, in the catalyst of the present invention, the performance is not lowered, so that the regeneration process is not required.

In the prior art disclosed in Japanese Laid-Open Patent Publication No. 2005-288380, the presence of water vapor is indispensable, and the higher the concentration of the water vapor, the higher the performance. Incidentally, if the relative humidity is less than 80%, it is not practical and the performance is lowered. On the other hand, when the catalyst of the present invention is used, unlike the above-described prior art, if the relative humidity is 30% or more, and preferably 60% or more, practical performance can be ensured, so that the above-described humidity control is not required. Operation, or no need for water spray Simple cooling such as fog. The humidification operation does not require the implementation of sprinkling regeneration treatment, and stable desulfurization performance can be obtained.

Further, in the carbon-based catalyst of the present invention, immersion, ion exchange or support of iodine or bromine is carried out, and water repellency treatment is applied, and sulfuric acid on the carbon-based catalyst is used even after long-term use. The amount of accumulation is also small, and since the cumulative amount is not increased blindly, stable desulfurization performance can be maintained without performing regeneration treatment. As described above, since the carbon-based catalyst is subjected to the water repellency treatment, even if the catalyst is kept in a wet state due to industrial water or an aqueous sulfuric acid solution, the dried portion can be maintained to obtain stable performance, and therefore, it is also possible to often Industrial water or a sulfuric acid aqueous solution or the like is sprayed on the above carbon-based catalyst and used.

Further, according to the present invention, there is provided a method of reacting said sulfurous acid gas with said oxygen and water vapor to form sulfuric acid by contacting with an exhaust gas containing at least sulfurous acid gas, oxygen and water vapor, and recovering said sulfuric acid A method for producing a carbon-based catalyst for flue gas desulfurization, characterized in that after a carbon-based catalyst is wetted and the pores are closed, a solution containing iodine, bromine or a compound thereof is sprayed or dispersed to the carbon-based catalyst. Alternatively, the carbon-based catalyst may be immersed in the solution to impregnate the iodine, bromine or a compound thereof on the surface of the carbon-based catalyst to form ion exchange or support.

In the above method, the carbon-based catalyst is preferably activated carbon or activated carbon fiber. Further, it is preferable that the iodine or a compound thereof is immersed in the iodine in a range of from 0.020% by weight to 60% by weight or less to form ion exchange or support to the carbon-based catalyst. Alternatively, the bromine or the compound thereof is impregnated and formed by the bromine being in the range of 0.010% by weight or more and 60% by weight or less. Ion exchange or support to the above carbon-based catalyst. Further, it is preferable to apply a water repellency treatment to the above carbon-based catalyst.

In the above method, if the carbon-based catalyst is wetted and the pores are closed, the carbon-based catalyst and water may be placed in a container, and the inside of the container may be depressurized and maintained for a certain period of time, and then returned to atmospheric pressure. This causes the water to be immersed in the pores of the carbon-based catalyst. Or, in the carbon-based catalyst, the mixed gas of water vapor and air is ventilated and the water vapor is condensed, thereby sealing the pores of the carbon-based catalyst with condensed water.

The carbon-based catalyst for flue gas desulfurization obtained by the production method of the present invention contains at least sulfite gas by immersing iodine, bromine or a compound thereof on the surface of the carbon-based catalyst to form ion exchange or support. When the exhaust gas of oxygen and water vapor is in contact with each other, as in the above formulas 1 and 2, iodine or the like on the carbon-based catalyst acts as a catalyst auxiliary agent, thereby improving the desulfurization performance.

When the iodine or the like is immersed in the surface of the carbon-based catalyst to form ion exchange or support, the iodine or the like is immersed to form ion exchange or support in the fine pores of the carbon-based catalyst. However, in the early stage after the desulfurization of the above-mentioned exhaust gas is started, the pores of the carbon-based catalyst are buried by the generated sulfuric acid, which is disadvantageous for the subsequent reaction.

In this regard, in the production method of the present invention, since the carbon-based catalyst is wetted in advance and the pores are closed, the immersion, ion exchange or support step of the iodine or the like is further performed, so that contact sulfation is continuously performed. In the vicinity of the surface of the carbon-based catalyst to be reacted, the iodine or the like can be mainly immersed, ion-exchanged or supported, and the additives such as iodine can be more effectively utilized.

In the production method of the present invention, when the carbon-based catalyst is wetted and the pores are closed, the air of the pores of the carbon-based catalyst is not easily dissipated, and the carbon-based catalyst itself has a certain degree of water repellency. The above carbon-based catalyst is forcibly immersed or placed in a liquid for a relatively long period of time. Therefore, for example, a so-called reduced pressure impregnation method or a steam addition method can be used.

Further, at this time, if the carbon-based catalyst is subjected to the water-repellent treatment, the generated sulfuric acid can be discharged from the carbon-based catalyst at an early stage. In this case, the water-repellent treatment step of the carbon-based catalyst can be carried out as a wetting step of the pores of the carbon-based catalyst, a immersion of the iodine or the like, and a pretreatment of the ion exchange or the supporting step. Or as a post-processing implementation.

After the immersion, ion exchange or support step of the above iodine or bromine is carried out, the water repellency treatment step is carried out, and then the step of blocking the pores of the carbon-based catalyst may be used to cause iodine volatilization or iodine due to overheating. The redissolution and desorption are not effective, and if sufficient iodine support is to be ensured, the water repellency becomes insufficient, and as a result, the treatment performance is lowered. Therefore, it is preferred to carry out the step of blocking the pores of the carbon-based catalyst after performing the water-repellent treatment step and the molding step, and then performing the immersion, ion exchange or support step of the above iodine or bromine.

If the step of sealing the pores of the carbon-based catalyst is carried out after performing the water-repellent treatment step, the carbon-based catalyst discharges the water. Therefore, when the water-repellent treatment is applied to the carbon-based catalyst as a pretreatment, it is preferred to use a vacuum impregnation method or a steam addition method.

Further, when it is considered that the carbon-based catalyst itself has high water repellency, even if a vacuum depressing method is employed, in order to sufficiently close the pores by water, It takes a long time. Therefore, the steam addition method is more desirable. At this time, in consideration of the dispersion of the gas, the aeration method of the mixed gas to the activated carbon is preferably an upward flow.

The immersion, ion exchange or support amount of the iodine or a compound thereof to the carbon-based catalyst is limited to a range in which iodine is in the range of 0.020% by weight or more and 60% by weight or less, and the bromine or a compound thereof is added to the carbon-based catalyst. The reason why the immersion, the ion exchange or the support amount is limited to the range in which the bromine is in the range of 0.010% by weight or more and 60% by weight or less, as described later, is that if the iodine or the bromine is out of the above range, the desulfurization activity ratio is lowered.

Furthermore, according to the present invention, there is provided a mercury adsorbing material which is a mercury adsorbing material for adsorbing and removing metallic mercury from an exhaust gas containing metal mercury, sulfurous acid gas, oxygen and water, and is characterized in that: On the surface of the carbon-based material, a mercury removing agent, in particular, iodine or bromine or a compound thereof is supported, and the carbon-based material is subjected to a water repellency treatment. The mercury adsorbing material of the present invention prevents the decrease in the adsorption capacity of mercury due to moisture or moisture by applying a water repellency treatment, and increases the adsorption capacity of mercury by supporting iodine or bromine or a compound thereof, and promotes the discharge. The oxygen in the gas is absorbed, and the mercury adsorption region is maintained in an oxidizing environment, and by these overall effects, the metal mercury in the exhaust gas is efficiently adsorbed and removed.

The carbon-based material used in the mercury adsorbing material of the present invention uses fine-particle activated carbon. In order to increase the surface area, the activated carbon is preferably fine. However, if the power or the step to be pulverized into fine particles is considered, the degree of fineness of the particles is still limited, and the excessively fine activated carbon has a disadvantage that it is difficult to handle. In contrast, if activated carbon After pulverizing into an average particle diameter of 20 to 200 μm and then forming it into a granular shape, a pellet shape, a flake shape, or a honeycomb shape by secondary molding, the disadvantage can be eliminated. In this case, when the average particle diameter of each of the activated carbon fine particles is less than 20 μm, moisture or sulfuric acid is retained between the particles to prevent gas-liquid contact. When the average particle diameter exceeds 200 μm, the gas-liquid contact is lowered and the activity cannot be improved.

The compound of iodine or bromine used in the mercury adsorbing material of the present invention is preferably an alkali metal salt of iodine or bromine, a metal salt of an alkaline earth, a transition metal salt, a hydride, an oxo acid or an organic compound. Iodine or bromine or a compound thereof (hereinafter referred to as "iodine or the like") is supported on the surface of the carbon-based material. For example, a carbon-based material such as activated carbon pulverized by fine particles can be immersed in these aqueous solutions or by a general method. The solution is dried in an organic solvent (alcohol or the like). At this time, iodine or the like is supported by the carbon-based material in the form of ion exchange or physical adsorption.

Iodine or the like is preferably supported by 0.001 to 0.8 mg atoms per gram of the carbon-based material in terms of iodine or bromine atoms. When the carbon-based material is 0.001 mg or less per gram of the carbon-based material, the supporting effect is hardly obtained. On the other hand, when 0.8 mg or more is supported, iodine or the like flows out into the liquid.

The present inventors added 625 mL (liquid-solid ratio: 25 mL/g) of a 20% aqueous sulfuric acid solution containing a specific amount of potassium iodide, and added it to activated carbon pulverized into fine particles (product name: Kuraraycoal, average particle size about 25 μm of 25 g was stirred for 24 hours under the open atmosphere to cause oxygen absorption, and the iodine adsorption amount of activated carbon was determined from the concentration of iodide remaining in the liquid. The result is shown in Figure 9. Available from Figure 9 It is known that when the iodine adsorption amount is 0.5 mg atom per 1 g of activated carbon, the iodine adsorption rate of activated carbon is more than 90%, but when the iodine adsorption amount is 0.8 mg atom per 1 g of activated carbon (at this time, When the amount of iodine added is about 1.5 mg atom per 1 g of activated carbon, the iodine adsorption rate of activated carbon is lowered to about 60%.

When the amount of iodine adsorption is further increased, and for every 1 g of activated carbon exceeding 0.8 mg atom, the iodine adsorption rate is rapidly lowered, so that the equilibrium concentration of iodine present in the liquid becomes high. As a result, when the mercury is removed, the iodine contained in the production liquid or the circulating liquid from the adsorption material is increased, and the iodine support amount of the activated carbon is gradually lowered by the iodine detachment. Iodine support is also unable to maintain the original high support. Regarding bromine, the same tendency as iodine can also be observed. From these points of view, the support amount of iodine or the like should be limited to 0.8 mg atom per 1 g of activated carbon.

Furthermore, the detachment of iodine into the circulating liquid is not ideal from the viewpoint of preventing iodine from being discharged outside the system. According to an experimental study by the present inventors, when 0.13 milliatoms of iodine is supported per 1 g of activated carbon, iodine is hardly contained in the circulating liquid, but when 0.8 mg of iodine is supported per 1 g of activated carbon, About 30 mg/L of iodine is contained in the circulating fluid. Therefore, in order to surely prevent iodine from being discharged outside the system, the activated carbon or the ion exchange resin may be contacted to remove iodine before the circulating liquid is supplied to the wet flue gas desulfurization device. When the wastewater from the flue gas desulfurization device is treated, it is effective to remove iodine according to activated carbon adsorption or ion exchange. The removed iodine can be recycled and reused. When the iodine support is increased to more than 0.8 milligrams per 1g of activated carbon, the concentration of iodine in the circulating fluid can be seen as The tendency of the number function to rise.

In the water-repellent treatment of the carbon-based material of the mercury adsorption material of the present invention, it is preferred that the carbon-based material contains a resin having a contact angle with water of 90 degrees or more, or a carbon-based material is applied before the support of iodine. The heat treatment is carried out to remove the hydrophilic groups of the surface and thereby proceed. Alternatively, these methods can be combined to perform water repellency treatment. By applying the water repellency treatment, it is possible to provide an adsorbent material having high desulfurization performance and capable of effectively removing mercury. When the iodide such as potassium iodide is supported on the carbon-based material subjected to the water-repellent treatment, it is preferred to add an oxidizing agent such as hydrogen peroxide or hypochlorous acid or to foam the air during the supporting.

Furthermore, according to the present invention, there is provided a method of desulfurizing a flue gas, characterized in that an exhaust gas containing metal mercury, sulfurous acid gas, oxygen and moisture is brought into contact while maintaining the wet state of the mercury adsorbing material. A mercury adsorbing material in which iodine or bromine or a compound thereof (hereinafter referred to as "iodine or the like") is supported on the surface of the carbonaceous material after the hydration treatment is applied. Preferably, the exhaust gas is passed through an adsorption tower filled with the above-mentioned mercury adsorbing material. The filling layer can be a fixed seat or a semi-continuous operation as a moving seat. According to this method, the adsorbent material can remove mercury and exert a desulfurization effect, so that the load of the separately arranged flue gas desulfurization device can be reduced, and the entire energy saving effect can be achieved.

The above-mentioned exhaust gas is preferably an outlet gas of the wet flue gas desulfurization device. Since the divalent mercury or sulfurous acid gas in the exhaust gas is removed in the wet flue gas desulfurization apparatus, the metal mercury adsorption capacity of the mercury adsorbent of the present invention can be effectively utilized. Although the outlet gas of the wet flue gas desulfurization device contains a large amount of water, since the mercury adsorbent material of the present invention is subjected to water repellency treatment, It is not easy to be wet, and it does not greatly damage the mercury removal effect due to the presence of moisture. Further, since the periphery of the mercury adsorbing material is wet, the sulfurous acid gas remaining in the outlet gas can be effectively removed. The sulfurous acid gas absorbent of the wet flue gas desulfurization apparatus generally uses limestone, but is not limited thereto, and other alkali chemicals such as caustic soda may be used. Since the mercury adsorbing material of the present invention exhibits a mercury removing effect even in a humid environment, it is not only the outlet gas of the wet flue gas desulfurization apparatus, but can be suitably used even if the outlet gas of the water washing tower is treated.

Preferably, the wet state is maintained by spraying industrial water or a dilute sulfuric acid solution to the mercury adsorbing material, and the effluent flowing from the mercury adsorbing material is supplied to the wet flue gas desulfurizing device. At this time, the air may be introduced into industrial water or a dilute sulfuric acid solution, or an acidifying agent may be added. In this case, the inlet and the outlet of the adsorption tower in which the mercury adsorption material is filled may be sampled to measure the mercury concentration, and when the mercury removal performance of the mercury adsorption material becomes a specific value or less, the amount of introduced air is increased. Or the amount of oxidant, thereby recovering the mercury removal performance of the mercury adsorbing material. The reduced mercury removal performance can also be recovered or complemented by adding iodine or the like to the above industrial water or dilute sulfuric acid solution.

The molar concentration of oxygen in the exhaust gas is preferably 10 times or more of the molar concentration of the sulfurous acid gas (the molar ratio of oxygen to sulfurous acid gas is 10) or more. In this case, for example, if iodine is supported on the activated carbon, iodine oxidizes the metal mercury in the exhaust gas and fixes it as iodized mercury. However, if the proportion of the sulfurous acid gas is more than oxygen, it will be reduced. Environment, such that the oxygen in the exhaust gas reaches the stabilized iodine or the generated mercury iodide is reduced, so that The mercury adsorption capacity is lowered, or once the adsorbed mercury is discharged again, or the iodine coexists in the circulating fluid of the adsorbent material and is discharged to the outside of the system, thereby causing secondary pollution. Therefore, it is preferable to measure the oxygen concentration of the exhaust gas and the sulfuric acid gas concentration, and introduce the air into the exhaust gas so that the molar concentration of oxygen becomes 10 times or more of the molar concentration of the sulfurous acid gas. However, if air is introduced into the exhaust gas and the amount of exhaust gas to be treated is increased, there is a concern that the mercury removal rate is lowered. Therefore, the molar ratio of oxygen to sulfurous acid gas is preferably 5,000 or less.

First, an embodiment of the carbon-based catalyst for flue gas desulfurization according to the present invention will be described.

The carbon-based catalyst for desulfurization of the flue gas is finally formed into a granular, agglomerate, or honeycomb structure, and the exhaust gas containing sulfurous acid gas, oxygen, and water vapor, and the dust particles coexisting with the exhaust gas are passed through. The shape. As the carbon-based catalyst to be the main body, a carbon raw material such as thermal decomposition carbon or coal hydrocarbon can be used, and it is preferable to use activated carbon or activated carbon fiber. Here, the activated carbon is preferably formed into a granular form, a fibrous form, or a coal coke as a raw material. Further, it is also possible to use a heat treatment of the above activated carbon or the like to increase the desulfurization activity.

The surface of the carbon-based catalyst can be applied by a fluororesin such as polytetrafluoroethylene having a contact angle of water of 90 or more, a water-repellent resin such as a polypropylene resin, a polyethylene resin or a polystyrene resin. Water treatment. Further, on the surface of the carbon-based catalyst, iodine, bromine or a compound thereof is impregnated to form ion exchange or support. The above iodine or a compound thereof is in contact with the above carbon system The impregnation, ion exchange or support amount of the medium is preferably in the range of 0.020 wt% or more and 60 wt% or less. Further, the amount of immersion, ion exchange or support of the bromine or the compound thereof to the carbon-based catalyst is preferably in the range of 0.010% by weight or more and 60% by weight or less. Further, as described later, the immersion, ion exchange or support amount of the above-mentioned iodine, bromine or a compound thereof to the above-mentioned carbon-based catalyst is in the range of 0.1% by weight to 10% by weight of iodine or bromine, and most suitably 0.1. Range of wt%~5wt%.

The iodine or bromine compound may be any of an alkali metal salt of iodine or bromine, a metal salt of an alkaline earth, a transition metal salt, a hydride, an oxo acid, and an organic compound. Specifically, the iodine compound may be an iodide such as lead iodide, nickel iodide, magnesium iodide, iron iodide or phosphorus iodide, iodic acid and iodide, methane iodide, iodine iodide or iodinated. Halogenated alkane such as propane, iodine propylene, diiodomethane or the like. Further, as the bromine compound, bromide, bromine, iron bromide or the like bromide, bromic acid and bromine salt, methyl bromide, brominated ethane or the like, a halogenated alkane, bromopropene or dibromomethane may be used. , dibromoethane, etc.

Next, an embodiment of the method for producing a carbon-based catalyst for exhaust gas desulfurization will be described. First, as a pretreatment, the carbon-based catalyst is subjected to a water-repellent treatment step and formed into a specific shape, and then the carbon-based catalyst is immersed in an aqueous solution such as water to form pores of the carbon-based catalyst. Wet and fill with the above aqueous solution. The step of impregnation, ion exchange or support of iodine or bromine is then carried out. The order in which these three steps are carried out can be appropriately selected.

First, as the material for subjecting the surface of the carbon-based catalyst to water repellency, a water-repellent resin having a contact angle with water of 90 degrees or more can be used. Specifically, there are resins such as polystyrene, polyethylene, polypropylene, or polychlorotrifluoroethylene. A fluororesin such as polytrifluoroethylene or polytetrafluoroethylene.

A method of applying a water repellency treatment to the surface of the carbon-based catalyst may be carried out by mixing a dispersion of the carbon-based catalyst with a water-repellent resin such as a fluororesin or a powder, or applying a shearing force. A method of kneading a carbon-based catalyst and a water-repellent resin to impregnate or support the water-repellent resin on the surface of the carbon-based catalyst. Further, particularly when a fluororesin is used, fibrillation can be generated on the surface of the carbon-based catalyst by applying a shearing force, and the fibers are bent and overlapped into a mesh shape, so that the surface of the catalyst is not completely blocked by the fluororesin. Instead, a water repellency treatment can be applied by a small amount of fluororesin.

Then, the above-mentioned forming step can be easily formed into the above-mentioned granular, agglomerated, honeycomb structure by kneading a carbon-based catalyst and a general organic binder (thermoplastic resin, thermosetting resin) and press molding. Wait. In this case, the above-mentioned fluororesin, polypropylene resin, polyethylene resin, polystyrene resin or the like, or a resin containing an acid-resistant resin of the water-repellent resin may be used simultaneously. Water treatment. Further, when a core material sheet or a nonwoven fabric containing the above-mentioned acid-resistant resin is added, the raw material of the carbon-based catalyst can be reduced or the strength can be improved.

Further, in order to close the pores of the carbon-based catalyst treated by the above-described molding step with the water, it is preferred to use a vacuum impregnation method or a steam addition method. In the vacuum impregnation method, the carbon-based catalyst is placed in a container, and then water is injected, and then the inside of the container is controlled to a specific temperature, and the internal air is exhausted by exhaust pumping to decompress the inside air. A method of returning the pressure in the vessel to atmospheric pressure after a certain period of time to 0.05 atmospheres or less. Steam adder, on the other hand In order to expose the carbon-based catalyst to a mixed gas in which water vapor is added to the air, the pores are filled with water. In this case, the higher the water vapor pressure in the air, the better, and it is preferable to, for example, mix the water vapor at 135 ° C with air to lower the temperature to 100 ° C, and to generate water vapor in the mixed gas. The way of condensation, to adjust the amount of water vapor and air.

Then, as a next step, a method of impregnating or supporting iodine or a compound thereof on the surface of the above carbon-based catalyst can be applied to dissolve the substances. Disperse in a hydrophilic solvent (such as water or alcohol) and spray this. spread. Impregnation. A method of immersing in the above-described carbon-based catalyst, or a method of kneading iodine or a compound thereof to the above-described carbon-based catalyst in the form of a fine powder or the solution. In addition, as a method of impregnating or supporting bromine or its compound, it is also suitable to dissolve these substances. A method of dispersing in a hydrophilic solvent and spraying the carbon-based catalyst, or a method of bringing gaseous bromine into contact with the carbon-based catalyst.

The mercury adsorbing material of the present invention is based on a carbon-based material, and iodine (I ₂ ) or bromine (Br ₂ ) or a compound thereof (hereinafter referred to as "iodine or the like") is supported on the surface thereof, and the carbon-based material is supported. The material is made by hydrating. The carbon-based material which can be used in the present invention is activated carbon, carbon fiber, carbon black, graphite, etc., but it is preferably activated carbon in consideration of support and water repellency treatment of iodine or the like. Activated carbon has various forms depending on the raw material and form, and these can be suitably used. However, if the granular activated carbon such as coal or coconut shell is used directly, the particle size is too large, and the effective contact area with the exhaust gas cannot be increased, and it is also difficult to perform water repellency treatment. Therefore, it is preferably pulverized into The average particle diameter (50% by particle diameter) is 20 to 200 μm and used.

When the iodine or the like is supported on a carbon-based material such as activated carbon, the carbon-based material may be impregnated with a solution obtained by dissolving iodine or the like in a volatile organic solvent such as water or an alcohol, and the solvent may be volatilized. The iodine or the like supported on the carbon-based material may be a monomer such as I ₂ or Br ₂ or an alkali metal salt such as KI, KBr, NaI or NaBr; or an alkaline earth metal such as CaI ₂ , CaBr ₂ , MgI ₂ or MgBr ₂ . Salt; transition metal salt of lead iodide, nickel iodide, iron iodide, iron bromide, etc.; hydride of HI, HBr, etc.; oxyacids of iodic acid, bromic acid, etc. and salts thereof; methane iodide, Organic compounds such as iodine propylene, diiodomethane, brominated ethane, bromopropene, etc.; other phosphorus bromide, iodine bromide, and the like. Preferably, an aqueous alkali metal salt solution of iodine or bromine such as KI or KBr is impregnated with a carbon-based material in an oxygen atmosphere. The solution containing iodine or the like is impregnated with a carbon-based material, and the carbon-based material may be immersed in a solution or sprayed to a carbon-based material. However, carbon-based materials generally have some degree of water repellency, so when water or a hydrophilic organic solvent is used as a solvent, the impregnation of the solution may take a long time. At this time, if a reduced pressure impregnation method is used, impregnation can be performed in a short time.

The carbon-based material is subjected to water-repellent treatment, and the water-repellent resin and the carbon-based material are sufficiently mixed, and then kneaded by a kneader. The water-repellent resin is preferably a resin having a contact angle with water of 90 degrees or more. The resin is preferably a fluororesin such as polytetrafluoroethylene, polychlorotrifluoroethylene or polytrifluoroethylene, and other resins such as polypropylene, polyethylene, and polystyrene may be used. In this case, when a dispersion of a fine particle-like resin in a form of water is used, it is easy to mix with a carbonaceous material in a fine particle form, and it is also preferable to knead it by a kneader after mixing. When used In the case of a fluororesin, it is particularly preferable to simply mix the water-repellent resin and the carbon-based material, and to perform a kneading operation later. In this case, the fine-particle-shaped resin is deformed by shearing force, and is stretched into a fibrous shape to cover the surface of the carbon-based material in a mesh shape, whereby the surface activity of the carbon-based material can be left, and a great dial can be obtained. The effect of water.

Alternatively, the carbon-based material may be subjected to a heat treatment to remove the hydrophilic group on the surface, thereby applying water-repellent treatment. When iodine or the like is supported by a carbon-based material and then heat-treated at a high temperature, since the supported iodine or the like may be volatilized, it is preferable to carry out iodine or the like after the heat treatment. Alternatively, when heat treatment is performed after supporting iodine or the like on a carbon-based material, it is preferred to carry out heat treatment at a relatively low temperature.

The carbon-based material which has been subjected to water-repellent treatment such as iodine or the like may be used as a particulate-shaped adsorbent material, and is used in a mercury adsorption tower for exhaust gas treatment, so that it is preferably formed into a size. Large granular, lumps, honeycombs, etc. Mixed with water-repellent resin. Since the carbon-based material after kneading is formed into a plastic block form, it can be used as it is, or if necessary, a binder is added, and it is press-formed into a flat shape using a roll. Further, a part of the obtained flat shaped article can be formed into a corrugated shape and laminated with the flat shaped article to produce a honeycomb shaped product. On the other hand, in the form of a fine particle, a suitable binder may be added and formed into a dough shape, or may be formed into a honeycomb shape in the same manner as in the case of a block.

Next, an embodiment of the mercury-absorbing material for smoke-exhausting treatment of the present invention will be described.

When the mercury adsorbing material of the present invention is used to remove mercury in the exhaust gas, The experimental setup shown in Figure 10 can be used. In Fig. 10, a mixed gas of nitrogen, oxygen, carbonic acid gas, and sulfurous acid gas is supplied from the gas supply unit 1, and is heated and humidified by warm water in the gas heating and humidifying unit 2. The mercury vapor is added thereto to form a simulated exhaust gas which is generated by bringing the nitrogen gas into contact with the metallic mercury in the mercury generating portion 3. The simulated exhaust gas formed is brought into contact with the absorption liquid in the gas-liquid contact portion 4. At this time, 70 to 90% of the sulfurous acid gas in the simulated exhaust gas is absorbed and removed. The gas-liquid contact portion 4 corresponds to a sulfurous acid gas absorption portion of a wet flue gas desulfurization device, and industrially, limestone is used as a sulfurous acid gas absorbent. In the case of an experimental device, a suitable alkali agent can be used instead of limestone. . The absorbing liquid that is in contact with the simulated exhaust gas in the gas-liquid contact portion 4 is circulated between the absorbing liquid oxidizing portion 5, and the oxidation-reduction potential (ORP) is adjusted by air aeration in the absorbing liquid oxidizing portion. Further, the pH is adjusted by the acid and alkali added from the pH adjusting liquid supply unit 6.

The outlet gas discharged from the gas-liquid contact portion 4 contains metal mercury which is not easily absorbed by the absorption liquid, and the metal mercury is used when the gas is passed through the adsorption tower 7 in which the mercury adsorption material of the present invention is filled. It is removed by adsorption. If the mercury adsorbing material is an activated carbon substrate, since it has a large specific surface area, it can effectively act as a contact interface with a gas. Since the mercury adsorbing material of the present invention is subjected to the water repellency treatment, even if it is in a wet state, the contact with the gas due to the water film or the sealing of the pores rarely occurs. Furthermore, since iodine or the like is supported on the surface, the mercury trapping ability is higher than that of the untreated activated carbon. Due to the combined action of these factors, the mercury adsorbing material of the present invention (especially an activated carbon matrix) ) has a large mercury adsorption capacity, and has a high mercury removal rate in the gas. The mercury removal rate can be obtained by sampling the gas at the inlet and outlet of the adsorption tower to determine the mercury concentration.

In the exhaust gas, sulfuric acid gas which is not absorbed and remains in the gas-liquid contact portion is also contained, but if the mercury adsorbing material of the present invention is maintained in a wet state, when the exhaust gas passes through the adsorption tower 7, sulfurous acid The gas on the surface of the adsorbent is oxidized by oxygen in the exhaust gas to be sulfuric acid and removed. In this way, the sulfurous acid gas removed from the exhaust gas is sulfuric acid and flows downward on the surface of the adsorbent, and is stored in the fixed seat liquid recovery unit 8. The liquid stored in the liquid recovery portion of the fixed seat is generally a dilute sulfuric acid solution obtained by mixing sulfuric acid flowing from the fixed material holder into industrial water, and the portion is recycled to the upper portion of the adsorption tower 7 and sprayed again to the mercury adsorption material. The other part is sent to the gas-liquid contact part and neutralized with sulfuric acid, and the mercury is treated together with the divalent mercury trapped by the flue gas desulfurization apparatus in a sewage treatment device or the like. When the ORP of the liquid sprayed to the mercury adsorbing material is to be increased in order to increase the removal rate, the air can be introduced as necessary, and various additives such as an oxidizing agent can be added from the additive liquid supply unit 9. When the amount of liquid is small, it is only necessary to replenish water to the liquid recovery section.

As described above, if the flue gas desulfurization apparatus which can efficiently remove the sulfurous acid gas is provided in the front stage of the mercury removal apparatus in which the mercury adsorption material of the present invention is filled, the combination of the two can be adopted. The sulfite gas and mercury are removed efficiently. Especially in the mercury removal device, the mercury can be removed without being affected by the sulfurous acid gas, and the residue can also be removed. Sulfuric acid gas.

In the exhaust gas discharged from the adsorption tower 7, although sulfurous acid gas and mercury are hardly contained, since the apparatus of Fig. 10 is an experimental apparatus, it may be tested under various conditions as a comparative example, and in this case, The exhaust gas after the treatment may contain mercury or the like, and the exhaust gas cannot be directly discharged. Therefore, the harmful substance removing device 10 is provided. Further, the mercury generating unit 3, the gas-liquid contact unit 4, the absorbing liquid oxidizing unit 5, the pH adjusting liquid supply unit 6, the adsorption tower 7, the fixed seat liquid collecting unit 8, and the additive liquid supply unit 9 are housed in an air temperature constant. Inside the slot 11.

[Example of carbon-based catalyst for flue gas desulfurization]

The following three types of commercially available granular activated carbon and two kinds of activated carbon fibers having the same iodine adsorption amount are prepared as the carbon-based catalyst to be a matrix.

(Comparative Example 1)

First, the above-mentioned activated carbons A to C and activated carbon fibers E and F were used as the carbon-based catalyst for flue gas desulfurization of Comparative Example 1 in comparison with the following Examples 1, 2, 3, 4 and 8, and only Rows after watering these Carbon-based catalyst for flue gas desulfurization. In other words, the polytetrafluoroethylene aqueous dispersion (resin solid content: 60% by weight, manufactured by DAIKIN Industries, Ltd.) was mixed to a particle size of 20 to 200 μm so that the solid content concentration became 10 parts by weight. The carbon A to C and 90 parts by weight of the activated carbon fibers E and F cut into 3 mm or less were kneaded by a pressure kneader, and then a flat sheet having a thickness of 0.8 mm was produced using a roll. Then, half of the flat sheet was processed into a wave shape by a gear-shaped roll, and the flat sheet was alternately laminated to obtain a honeycomb-type carbon-based catalyst for flue gas desulfurization.

The obtained honeycomb-shaped flue gas desulfurization was filled with an active carbon catalyst of 0.001 m ³ into a 50 mm×50 mm tetragonal catalyst packed column at a capacity of 1 m ³ /h, and the sulfuric acid gas was 1000 ppm by volume and the oxygen concentration was 5 The simulated exhaust gas formed by the temperature of 50 ° C formed by the capacity %, the carbonic acid gas 10% by volume, and the humidity of 80% passes through the catalyst layer, and the desulfurization performance of each carbon-based catalyst for flue gas desulfurization is obtained. The method for evaluating the desulfurization performance is to estimate the primary reaction for the concentration of sulfurous acid gas in the exhaust gas, and calculate the apparent velocity constant K ₀ by the following equation.

K ₀ = - (gas amount / catalyst amount) × Ln (1 - desulfurization rate) Desulfurization rate = 1 - (export sulfuric acid gas concentration / inlet sulfurous acid gas concentration) to obtain sulfur desulfurization by the present conditions The performance was used as a reference value for each catalyst (=desulfurization activity ratio of 1.0).

(First embodiment) (Example 1)

As the carbon-based catalyst for flue gas desulfurization of Example 1, the above-mentioned activity is used. The carbon A and the activated carbon fiber E are supported by the KI of the iodine compound on these catalysts, and the water-repellent treatment is carried out to produce the carbon-based catalyst for flue gas desulfurization of the present invention.

First, the pressure is reduced to impregnate the KI aqueous solution, and the activated carbon A pulverized to an average particle diameter of 20 to 200 μm and the activated carbon fiber E cut to 3 mm or less are supported. At this time, the amount of KI supported was dissolved and the amount of support was adjusted. Then, an aqueous dispersion of polytetrafluoroethylene (resin solid content: 60% by weight, manufactured by DAIKIN Industries, Ltd.) was mixed to the activated carbon A and activated carbon fiber holding the KI so that the solid content concentration became 10 parts by weight. The 90-weight portion of E was kneaded using a pressure kneader, and then a flat sheet having a thickness of 0.8 mm was produced using a roll. Then, from the flat sheet, the same method as in the above Comparative Example 1 was used, and a honeycomb-shaped activated carbon catalyst for flue gas desulfurization supporting KI having 5 wt% of iodine was obtained.

Here, the above-described decompression impregnation method will be specifically described as follows. First, activated carbon A is placed in a reduced pressure vessel, followed by water having a capacity of about 5 times the capacity of the activated carbon. Then, while controlling the temperature in the container at a constant temperature of 25 ° C, the air in the container was evacuated by using an exhaust pump, and the pressure was reduced to 0.05 or less. Thereafter, this state was maintained for about 12 hours, and then the pressure in the above vessel was returned to atmospheric pressure (1 atm).

Then, by using the same test conditions as in Comparative Example 1, the obtained activated carbon catalyst for deodorization of flue gas was subjected to a desulfurization test and the desulfurization performance was determined.

(Example 2)

In the carbon-based catalyst for desulfurization of the second embodiment, the activated carbon A and the activated carbon fiber E are used, and water is impregnated into the pores in advance, and the KI of the iodine compound is supported by the catalyst. The carbon-based catalyst for flue gas desulfurization of the present invention is produced by hydration treatment.

First, the water is impregnated with activated carbon A having an average particle diameter of 20 to 200 μm and activated carbon fiber E cut to 3 mm or less by the reduced pressure impregnation method described above, and the water is filled with activated carbon A and active. Fine pores of carbon fiber E. At this time, the amount of KI supported was dissolved and the amount of support was adjusted. Then, an aqueous dispersion of polytetrafluoroethylene (resin solid content: 60% by weight, manufactured by DAIKIN Industries, Ltd.) was mixed to the activated carbon A and activated carbon fiber holding the KI so that the solid content concentration became 10 parts by weight. The 90-weight portion of E was kneaded using a pressure kneader, and then a flat sheet having a thickness of 0.8 mm was produced using a roll. Then, from the flat sheet, the same method as in the above Comparative Example 1 was used, and a honeycomb-shaped activated carbon catalyst for flue gas desulfurization supporting KI having 5 wt% of iodine was obtained.

Then, by using the same test conditions as in Comparative Example 1 and Example 1, the obtained activated carbon catalyst for flue gas desulfurization was subjected to a desulfurization test to determine the desulfurization performance.

Fig. 1 is a comparison showing the carbon-based catalyst for flue gas desulfurization shown in the above Examples 1 and 2 obtained from the results of the above desulfurization test, and the carbon system for flue gas desulfurization of Comparative Example 1. The desulfurization activity ratio of the catalyst. As can be seen from the same figure, in the comparative example 1 in which only the activated carbon or the activated carbon fiber was subjected to the water repellency treatment, the activated carbon or the like was dialyzed and iodinated. In the catalyst of the first embodiment, the catalyst of the first embodiment can obtain a high desulfurization performance of about 1.5 times, and 2 to 2.5 can be obtained by the catalyst of the second embodiment in which pores of the activated carbon or the like are sealed with water in advance. More than the desulfurization performance.

(Second embodiment)

Next, in order to support iodine or a compound thereof in the case where the activated carbon or the like is supported, and in the case where bromine or a compound thereof is supported, it is verified whether or not the effect of improving the desulfurization performance is different, and the following Example 3 and the implementation are used. The flue gas desulfurization of Example 4 was verified by an activated carbon catalyst.

(Example 3)

In the activated carbon catalyst for flue gas desulfurization of Example 3, the activated carbon A to C and the activated carbon fibers E and F were previously impregnated with water by the same method as in Example 2. The KI of the iodine compound is supported by these catalysts and subjected to water repellency treatment, whereby the honeycomb-type activated carbon catalyst for flue gas desulfurization of the present invention which supports KI having 5 wt% of iodine is produced.

(Example 4)

Further, as the activated carbon catalyst for flue gas desulfurization of Example 4, the activated carbon A to C and the activated carbon fibers E and F were impregnated with water in advance in the same manner as in the second embodiment. After the pores, the KBr of the bromine compound is supported on these catalysts and subjected to water repellency treatment. A honeycomb-shaped activated carbon catalyst for flue gas desulfurization of the present invention in which KBr of 5% by weight of bromine is used is produced.

Then, the activated carbon catalyst for the honeycomb-type flue gas desulfurization of the above Examples 3 and 4 was subjected to a desulfurization test by the same test conditions as in Comparative Example 1 above, and the desulfurization performance was determined.

Fig. 2 is a comparison showing the carbon-based catalyst for flue gas desulfurization shown in the above Examples 3 and 4 obtained from the results of the above desulfurization test, and the carbon system for flue gas desulfurization of Comparative Example 1. The desulfurization activity ratio of the catalyst. From this figure, it can be seen that the catalyst supporting the iodine compound KI and the catalyst supporting the bromine compound KBr can be observed to have almost the same desulfurization effect as in Comparative Example 1.

(Third embodiment)

Next, the following active carbon catalysts for flue gas desulfurization of Examples 5 and 6 were used to verify how the support amount of iodine, bromine or a compound thereof affects the improvement of desulfurization performance.

(Example 5)

First, as the activated carbon catalyst for flue gas desulfurization of Example 5, by the same method as in Example 2, the activated carbon A was previously impregnated with water in the pores, and the KI of the iodine compound was changed. The amount of support is maintained in a range of 0.01% by weight to 80% by weight of iodine and subjected to water repellency treatment, thereby producing 20 kinds of honeycomb-type carbon-based catalysts for flue gas desulfurization of the present invention.

(Example 6)

Further, in the same manner as in Example 2, the activated carbon catalyst for exhaust gas desulfurization of Example 6 was subjected to the same method as in Example 2, and the activated carbon A was impregnated with water in advance to change the bromine. The support amount of the KBr of the compound is supported and hydrophobized in the range of 0.01% by weight to 80% by weight of the bromine, thereby producing five kinds of active carbon catalysts for the honeycomb-type flue gas desulfurization of the present invention. .

Then, by using the same test conditions as in the above Comparative Example 1, the activated carbon catalysts for the desulfurization of a plurality of honeycombs for desulfurization of the above-mentioned Examples 5 and 6 were subjected to desulfurization test and the desulfurization performance was determined. .

Fig. 3 is a graph showing the results of desulfurization tests of a plurality of catalysts which change the support amount of KI or KBr in Examples 5 and 6. According to the same figure, it can be seen that iodine and bromine can obtain almost the same desulfurization performance improvement effect for various supporting amounts. In addition, iodine compound KI supporting iodine in the range of 0.020 wt% to 60 wt% in activated carbon A Or, the bromine compound KBr supporting the bromine in the range of 0.010 wt% to 60 wt% can be used to obtain the effect of improving the desulfurization performance.

Here, the supporting amount of iodine, bromine or a compound thereof of activated carbon A, when iodine or bromine exceeds 10% by weight, although a desired effect can be obtained, an effect of increasing the amount of support is not obtained, and conversely, If the support amount is less than 0.1% by weight, the above effect will be relatively rapidly reduced. Further, particularly in the range of 5 wt% to 10 wt%, the rate of increase in the amount of support is not large. Therefore, iodine, bromine or a compound thereof is used for the above carbon-based catalyst. The preferred impregnation, ion exchange or support amount is from 0.1% by weight to 10% by weight, most suitably from 0.1% by weight to 5% by weight.

(Fourth embodiment)

Next, using the activated carbon catalyst for flue gas desulfurization in the following Example 7, it was confirmed whether or not the iodine compound was supported by the above activated carbon or the like, and whether the effect of improving the desulfurization performance was different due to the difference in the iodine compound.

(Example 7)

In the activated carbon catalyst for exhaust gas desulfurization of Example 7, the activated carbon A was used, and in the same manner as in Example 2, water was impregnated into the pores in advance, and iodine was 0.5 wt% of KI and MgI _{2, respectively.} The iodine compound of AlI ₃ and CuI is supported and subjected to water repellency treatment to produce a plurality of activated carbon catalysts for honeycomb deodorization of the present invention.

Then, by using the same test conditions as in the above Comparative Example 1, the obtained activated carbon catalysts containing a plurality of honeycomb-like flue-desulfurization desulfurizations with different iodine compounds were subjected to desulfurization test and desulphurization was determined. performance.

Figure 4 shows the test results. As can be seen from Fig. 4, even in the case of Comparative Example 1 in which the iodine compound was not supported, an excellent desulfurization performance-improving effect was obtained, and the above-mentioned improvement was not caused by the difference in the compound. The effect is quite different.

(Fifth Embodiment)

Next, using the activated carbon catalyst for flue gas desulfurization of the following Example 8, The desulfurization performance of the activated carbon catalyst for flue gas desulfurization of the present invention can be verified.

(Example 8)

In the activated carbon catalyst for exhaust gas desulfurization of Example 8, the activated carbon A was used, and in the same manner as in Example 2, water was impregnated into the pores in advance, and KI of 0.5% by weight of iodine compound was supported. The water repellency treatment is carried out to thereby produce the honeycomb-shaped activated carbon catalyst for flue gas desulfurization of the present invention. Thereafter, the long-term desulfurization test was carried out by the same test conditions as in Comparative Example 1 described above.

Figure 5 shows the test results. As can be seen from Fig. 5, the activated carbon catalyst for flue gas desulfurization according to the present invention can be maintained for at least 700 hours, that is, twice the desulfurization performance of Comparative Example 1.

(Sixth embodiment)

Next, it is confirmed that the carbon-based catalyst for the honeycomb-type flue gas desulfurization of the present invention in which the iodine or the like is supported and hydrophobized after the active carbon or the like is impregnated into the pores, How does a lower-water-based resin act as a binder for activated carbon, a catalyst that only supports activated carbon to support iodine, and a catalyst that only hydrophobizes activated carbon, and how to express more remarkable desulfurization performance. situation.

(Comparative Example 2)

First, as a carbon-based catalyst for flue gas desulfurization of Comparative Example 2, In the form of 10 parts by weight, the amide-based resin as a molding aid is mixed to 90 parts by weight of activated carbon A pulverized to an average particle diameter of 20 to 200 μm, kneaded by a pressure kneader, and then produced by using a heated roll. A flat sheet having a thickness of 0.8 mm is formed, and then half of the flat sheet is processed into a wave shape by a gear-shaped roll, and laminated with another flat sheet to obtain a honeycomb-like activity for desulfurization of flue gas. Carbon catalyst.

(Comparative Example 3)

In addition, as a carbon-based catalyst for exhaust gas desulfurization of Comparative Example 3, the water was impregnated with water to be pulverized into activated carbon A having an average particle diameter of 20 to 200 μm, and the pores of activated carbon A were injected with water. The KI aqueous solution was impregnated and supported under reduced pressure. At this time, the amount of KI supported was dissolved and the amount of support was adjusted. Then, the amide-based resin as a molding aid was mixed to 90 parts by weight of the activated carbon A holding the KI so as to be 10 parts by weight, and kneaded by a pressure kneader. From the kneaded product, a flat sheet having a thickness of 0.8 mm was produced by using a heating roll, and in the same manner as in the above Comparative Example 2, a honeycomb-shaped sheet containing KI of 5 wt% of iodine was obtained. Activated carbon catalyst for sulfur.

Then, the activated carbon catalyst for the honeycomb-type flue gas desulfurization of Comparative Example 2 and Comparative Example 3 was subjected to a desulfurization test by the same test conditions as in Comparative Example 1 described above, and the desulfurization performance was determined.

Fig. 6 is a control showing the carbon-based catalyst for flue gas desulfurization shown in the above Comparative Example 2 and Comparative Example 3 obtained from the results of the above desulfurization test, and the flue gas removal of Comparative Example 1 and Example 2. Desulfurization activity of carbon-based catalyst for sulfur ratio. As can be seen from the same figure, the catalyst of Comparative Example 2, which does not support iodine or the like and which has not been subjected to the water repellency treatment, does not perform the water repellency treatment, but blocks the pores with water and supports the iodine compound KI. In the catalyst of Comparative Example 3, an improvement in the desulfurization performance of about 1.5 times was obtained, and in the catalyst of Comparative Example 1 in which only the water repellent treatment was performed, only the effect of improving the desulfurization performance of about 10 times was observed.

On the other hand, the activated carbon catalyst for flue gas desulfurization according to Example 2 of the present invention in which the iodine compound KI is supported and water-repellent is impregnated with water, and the water is impregnated in advance. The synergistic effect of the impregnation effect of the pores, the supporting effect of the iodine compound, and the effect of the water repellency treatment was able to obtain an extremely high desulfurization performance improving effect of about 26 times with respect to the catalyst of Comparative Example 2.

(Seventh embodiment)

Next, it is confirmed that the above-described water repellent treatment is performed as the wetting step of the pores of the carbon-based catalyst, the immersion of the iodine or the like, the pretreatment of the ion exchange or the supporting step, and the post-treatment. In the case of the time, the time required for the treatment and the desulfurization activity ratio are affected by the vacuum impregnation method and the steam addition method, respectively.

(1) The humidification step is carried out by a reduced pressure impregnation method as a pretreatment of the water repellent treatment

At this time, the activated carbon catalyst for flue gas desulfurization is prepared in addition to the active carbon catalyst for the honeycomb deodorization of the above-mentioned Example 2, and is prepared in the container. The pressure is maintained for 6 hours; for 20 hours; and the temperature in the above container is not maintained at 25 ° C, but the temperature is raised to 60 ° C and the air in the above container is exhausted using an exhaust pump to decompress In the case of a pressure of 0.05 atmosphere or less and maintaining this state for 10 hours, a total of four types of activated carbon catalysts for flue gas desulfurization are used.

(2) The humidification step is performed by a steam addition method as a pre-treatment of the water-repellent treatment

(Example 9)

First, water vapor of 135 ° C is mixed with air, and the temperature is lowered to 100 ° C, and the amount of water vapor and the amount of air are adjusted so that the water vapor in the mixed gas is condensed. Next, the ventilation duct is partitioned by a sieve having a smaller particle size than that of the activated carbon, and the activated carbon A pulverized into an average particle diameter of 20 to 200 μm is filled therein.

Then, as the activated carbon catalyst for flue gas desulfurization of Example 9, it is prepared to mix the above in such a manner that GHSV (=gas amount (m ³ /h) ÷ activated carbon (m ³ )) becomes 5 to 10 h ^-1 . The gas is ventilated for 2 hours; the person who is ventilated for 5 hours; and the gas mixture is ventilated for 1 hour in a manner that the GHSV is 15 to 20 h ^-1 ; and the total of the ventilation is 2 hours. The gas temperature at the inlet of the activated carbon layer can be controlled to 100 ° C by adjusting the addition position of the water vapor at this time. At this time, the gas aeration method for the activated carbon is carried out by the upward flow.

Next, a reduced pressure was applied to impregnate the KI aqueous solution to support the activated carbon A described above. At this time, the amount of KI supported was dissolved and the amount of support was adjusted. Next, The aqueous polytetrafluoroethylene dispersion (resin solid content: 60% by weight, manufactured by DAIKIN Industries, Ltd.) was mixed to the activated carbon A and the activated carbon fiber E of KI at a weight of 10 parts by weight. The weight portion was kneaded using a pressure kneader, and then a flat sheet having a thickness of 0.8 mm was produced using a roll. Then, from the flat sheet, the same method as in Comparative Example 1 was used, and an activated carbon catalyst for exhaust gas desulfurization of Example 9 in which four kinds of KI having 5 wt% of iodine were supported was obtained.

(3) The humidification step is carried out by a reduced pressure impregnation method as a post-treatment of the water-repellent treatment

(Embodiment 10)

First, a honeycomb-shaped activated carbon catalyst was obtained by the same method as in Comparative Example 1, and then the honeycomb-shaped activated carbon catalyst was placed in a reduced pressure vessel, and then the activated activated carbon catalyst was introduced into the honeycomb. The volume is approximately 5 times the volume of water. Then, while controlling the temperature in the container at a constant temperature of 25 ° C, the air in the container was evacuated by using an exhaust pump, and the pressure was reduced to 0.05 or less.

Then prepare: maintain the pressure in the vessel to atmospheric pressure (1 atm) after maintaining this state for 12 hours; maintain the pressure in the vessel to atmospheric pressure after maintaining this state for 30 hours; and not maintain the temperature in the vessel At 25 ° C, the temperature is raised to 60 ° C and the air in the above container is exhausted by exhaust pumping, and the pressure is reduced to 0.05 atmosphere or less, and the pressure in the container is returned to the atmospheric pressure after maintaining the state for 25 hours. A total of three kinds of honeycomb-shaped activated carbon catalysts.

Then, the KI aqueous solution is sprayed or the KI aqueous solution is decompressed and impregnated and supported in the honeycomb activated carbon catalyst. At this time, the amount of KI supported was dissolved and the amount of support was adjusted, and three kinds of active carbon catalysts for exhaust gas desulfurization of Example 10 in which honeycombs of KI having 5 wt% of iodine were supported were obtained.

(4) The humidification step is performed by a steam addition method as a post-treatment of the water-repellent treatment

(Example 11)

First, a honeycomb-shaped activated carbon catalyst was obtained by the same method as in Comparative Example 1, and then the honeycomb-shaped activated carbon catalyst was stored in the same ventilation duct as in Example 9 to obtain water vapor at 135 °C. After mixing with air, the mixture is cooled to 100 ° C, and the amount of steam and the amount of air are adjusted so that the water vapor is condensed, and the mixed gas is ventilated by the upward flow. At this time, the gas temperature at the inlet of the activated carbon layer was controlled at 100 °C.

After that, the gas mixture is ventilated for 3 hours in a manner that the GHSV is 5 to 10 h ^-1 ; the aeration is performed for 5 hours; and the mixed gas is ventilated for 1 hour in a manner that the GHSV is 15 to 20 h ^-1 ; The total amount is four kinds of honeycomb-shaped activated carbon catalysts.

Then, the KI aqueous solution is sprayed or depressurized in the honeycomb active carbon catalyst to impregnate the KI aqueous solution. At this time, the amount of KI supported was dissolved and the amount of support was adjusted to obtain four kinds of active carbon catalysts for exhaust gas desulfurization of Example 11 in which honeycombs of KI having 5 wt% of iodine were supported.

Using the activated carbon catalysts for exhaust gas desulfurization of these Examples 2, 9, 10 and 11, the desulfurization test was carried out by the same test conditions as in Comparative Example 1 described above, and the desulfurization performance was determined. Fig. 7 and Fig. 8 are graphs showing the results of the treatment time and desulfurization performance required for the wetting step required for the production of these activated carbon catalysts for flue gas desulfurization.

As can be seen from these figures, when the wetting step is carried out, the wetting step can be performed before or after the water immersion treatment, whether it is according to the vacuum impregnation method or the steam addition method, and the wetting step can be performed. The activated carbon catalyst for desulfurization of flue gas desulfurization of Example 1 (desulfurization activity ratio of 1.6) obtained higher desulfurization performance.

In addition, when the humidification step is carried out, by using a steam addition method, an active carbon touch for exhausting and desulfurizing having the same desulfurization performance can be obtained in a shorter treatment time than by using a vacuum impregnation method. Media.

[Example of mercury-discharging treatment mercury adsorption material] (Embodiment 12)

Activated carbon (product name: Kuraraycoal) was pulverized to an average particle diameter of about 50 μm using a vibration mill. The obtained fine particle-shaped activated carbon is impregnated into a 20% sulfuric acid aqueous solution containing potassium iodide, and air-dried, whereby the iodine support amount is 0.5 mg atom/g-activated carbon in terms of iodine atom. Iodine is supported. The polytetrafluoroethylene aqueous dispersion (D-1E manufactured by DAIKIN Industries, Ltd., 60% by weight of the resin solid content) was mixed to the iodine-supporting activated carbon thus prepared, so that the solid content concentration became 10 parts by weight. For the weight, use a pressure kneader to pinch the mixture After that, a flat sheet having a thickness of 0.8 mm was produced using a roll. Then, half of the flat sheet was processed into a wave shape by a gear-like roll, and the obtained corrugated sheet was alternately laminated with the remaining unprocessed flat sheet, thereby obtaining a honeycomb-shaped fixing seat.

An experiment for removing mercury in the simulated exhaust gas was performed using the apparatus of Fig. 10. 0.25 L of the honeycomb filler prepared in the above manner was filled in a 50 mm × 50 mm tetragonal catalyst packed column, and a simulated exhaust gas having a temperature of 50 ° C was passed through the catalyst packed column at 0.5 m ³ /h. The composition of the simulated exhaust gas at this time was a metal mercury gas concentration of 30 ppb, a sulfurous acid gas concentration of 1000 ppm by volume, an oxygen concentration of 5% by volume, a carbonic acid gas concentration of 10% by volume, and a moisture content of 12% by volume, and the balance was nitrogen. The desulfurization rate in the gas-liquid contact portion 4 is about 80%. The liquid stored in the fixed seat liquid recovery unit 8 was circulated to the upper portion of the holder at 0.5 L/hour, and sprayed from above to the honeycomb filler. Further, air is not introduced into the fixed seat liquid recovery unit. At the time of 300 hours, 700 hours, and 1000 hours from the start of the aeration, the mercury concentration in the simulated exhaust gas at the inlet and outlet of the fixed seat was measured, and the mercury removal rate was calculated. The results are shown in Table 1. The sulfite gas is removed in the gas-liquid contact portion and the holder, and the sulfuric acid gas removal rate at the outlet of the holder can be maintained at 98% or more even after 1000 hours.

(Comparative Example 4)

A honeycomb-shaped filler was produced in the same manner as in Example 12 except that the step of impregnating the activated carbon in the form of fine particles with potassium iodide aqueous solution was omitted, and the simulated exhaust gas was removed under the same conditions as in Example 12. The experiment of mercury. The results are shown in Table 1.

(Comparative Example 5)

Activated carbon (product name: Kuraraycoal) was pulverized to an average particle diameter of about 50 μm using a vibration mill. The obtained fine particle-shaped activated carbon is impregnated with a 20% aqueous sulfuric acid solution containing potassium iodide, whereby the iodine support amount is such that iodine is supported so as to be 0.5 mg atom/g-activated carbon in terms of iodine atom. The amide-based resin and the polyethylene-based resin, which are molding aids, are mixed to 90 parts by weight of the iodine-supporting activated carbon thus prepared, and the mixture is kneaded by a pressure kneader. A flat sheet having a thickness of 0.8 mm was produced using a roll. Then, half of the flat sheet was processed into a wave shape by a gear-like roll, and the obtained corrugated sheet was alternately laminated with the remaining unprocessed flat sheet, thereby obtaining a honeycomb-shaped fixing seat. Using the honeycomb-shaped filler thus produced, an experiment for removing mercury in the simulated exhaust gas was carried out under the same conditions as in Example 12. The results are shown in Table 1.

(Comparative Example 6)

Except that the step of impregnating the activated carbon in the form of fine particles with potassium iodide aqueous solution was omitted, a honeycomb-shaped filler was produced in the same manner as in Comparative Example 5, and mercury in the simulated exhaust gas was removed under the same conditions as in Example 12. Experiment. The results are shown in Table 1.

(Example 13)

A honeycomb-shaped filler was produced in the same manner as in Example 12. The prepared honeycomb-shaped filler 0.25 L was filled in a 50 mm × 50 mm quadrilateral catalyst packed column, and a simulated exhaust gas having a temperature of 50 ° C was passed through the catalyst packed column at 0.5 m ³ /h. The composition of the simulated exhaust gas at this time was a metal mercury gas concentration of 30 ppb, a sulfurous acid gas concentration of 1000 ppm by volume, an oxygen concentration of 5% by volume, a carbonic acid gas concentration of 10% by volume, and a moisture content of 12% by volume, and the balance was nitrogen. The liquid stored in the liquid recovery portion for the fixed seat was circulated to the upper portion of the holder at 0.5 L/hour, and sprayed from above to the honeycomb filler. Air is not introduced into the fixed seat liquid recovery unit. After 700 hours from the start of the aeration, the oxygen concentration at the inlet of the packed column was changed in the range of 0 to 5 % by volume. At this time, the concentration of sulfurous acid gas was kept constant, and the molar ratio of oxygen/sulfuric acid gas was changed to investigate the influence on the mercury removal rate. The result is shown in Figure 11. As can be seen from Fig. 11, if the molar ratio of oxygen/sulfuric acid gas is 10 or more, a high mercury removal rate of 85% can be obtained, whereas the molar ratio of oxygen/sulfuric acid gas is relatively high. In small conditions, the mercury removal rate is low. Therefore, when the concentration of oxygen flowing into the exhaust gas of the adsorption tower is extremely low, it is preferable to introduce air into the exhaust gas to increase the molar ratio of the oxygen/sulfuric acid gas to 10 or more.

(Example 14)

A honeycomb-shaped filler was produced in the same manner as in Example 12, and the air was introduced into the fixed-tank liquid recovery portion at 30 L/hour, and the simulated exhaust gas was removed under the same conditions as in Example 12. The experiment of mercury. As a result, the mercury removal rate at the time of 700 hours from the start of the aeration was 95%. From this result, it is understood that the method of introducing air into the liquid sprayed to the mercury adsorbing material in advance to increase the ORP is effective.

The present application claims priority based on Japanese Patent Application No. 2008-071771, filed on Jan.

1‧‧‧Gas Supply Department

2‧‧‧Gas Heating and Humidification Department

3‧‧‧ Mercury Production Department

4‧‧‧ gas-liquid contact

5‧‧‧Absorbing liquid oxidation department

6‧‧‧pH adjustment liquid supply department

7‧‧‧Adsorption tower

8‧‧‧Fixed seat recovery unit

9‧‧‧Additive Liquid Supply Department

10‧‧‧Hazardous material removal equipment

11‧‧‧Air bath

Fig. 1 is a graph showing the results of the desulfurization tests of Comparative Examples 1 and 2 using the carbon-based catalyst of the present invention in the first embodiment and Comparative Example 1 using a conventional carbon-based catalyst.

Fig. 2 is a graph showing the results of the desulfurization tests of Comparative Examples 1 and 4 using the carbon-based catalyst of the present invention in the second embodiment and Comparative Example 1 using a conventional carbon-based catalyst.

Fig. 3 is a graph showing the results of the desulfurization tests of Examples 5 and 6 using the carbon-based catalyst of the present invention in the third embodiment.

Fig. 4 is a view showing the use of the carbon-based catalyst of the present invention of the fourth embodiment. A graph of the results of the desulfurization test of Example 7.

Fig. 5 is a graph showing the results of the long-term desulfurization test of Example 8 using the carbon-based catalyst of the present invention in the fifth embodiment and Comparative Example 1 using the conventional carbon-based catalyst.

Fig. 6 is a graph showing the results of the desulfurization test of Example 2 using the carbon-based catalyst of the present invention in the sixth embodiment and Comparative Examples 1, 2 and 3 using the conventional carbon-based catalyst.

Fig. 7 is a graph showing the time required for the water repellency treatment and the desulfurization performance of Examples 2, 9, 10 and 11 of the carbon-based catalyst of the present invention in the seventh embodiment.

Fig. 8 is a graph showing the ratio of the hydration treatment conditions and the desulfurization activity ratio of Examples 2, 9, 10 and 11 of the carbon-based catalyst of the present invention in the seventh embodiment.

Fig. 9 is a graph showing the relationship between the amount of iodine added in the liquid and the amount of iodine adsorbed by the activated carbon.

Fig. 10 is a view showing an example of an apparatus for carrying out the smoke evacuation treatment method using the mercury adsorption material of the present invention.

Figure 11 shows the relationship between the molar ratio of oxygen/sulfuric acid gas in the simulated exhaust gas and the mercury removal rate.

Claims (13)

A carbon-based catalyst which reacts with the above-mentioned oxygen and water vapor to form sulfuric acid by contacting with an exhaust gas containing at least sulfurous acid gas, oxygen and water vapor, and recovers the sulfuric acid from the sulfuric acid A carbon-based catalyst for sulfur, characterized in that the carbon-based catalyst has a surface impregnated with ion, or supported by iodine, bromine or a compound thereof, and the carbon-based catalyst is subjected to water repellency treatment, and the water-repellent treatment is performed. As a result of the treatment, the carbon-based catalyst contains a resin having a contact angle with water of 90 degrees or more, and the surface of the carbon-based catalyst is impregnated, ion-exchanged or supported by iodine, bromine or a compound thereof, and placed in a container. The carbon-based catalyst and the water are depressurized in the container for a predetermined period of time, and then returned to atmospheric pressure, or a mixed gas of water vapor and air is ventilated to the carbon-based catalyst to condense the water vapor. After the pores of the carbon-based catalyst are wetted with water, a solution containing iodine, bromine or a compound thereof is sprayed or dispersed to the carbon-based catalyst, or the carbon-based catalyst is immersed in the solution. A carbon-based catalyst according to claim 1, wherein the carbon-based catalyst is activated carbon or activated carbon fiber. The carbon-based catalyst according to claim 2, wherein the activated carbon is a molded body formed of fine-particle activated carbon having an average particle diameter of 20 to 200 μm. The carbon-based catalyst of the first aspect of the patent application, wherein the compound of the above iodine or bromine is an alkali metal salt of iodine or bromine, a metal salt of an alkaline earth, Any of a transition metal salt, a hydride, an oxo acid, and an organic compound. The carbon-based catalyst according to claim 1, wherein the iodine is in a range of from 0.020% by weight to 60% by weight based on the immersion, ion exchange or support amount of the above-mentioned carbon-based catalyst. The carbon-based catalyst according to claim 1, wherein the bromine is in a range of from 0.010% by weight to 60% by weight based on the immersion, ion exchange or support amount of the above-mentioned carbon-based catalyst. The carbon-based catalyst according to the first aspect of the invention, wherein the amount of the iodine or bromine or the compound thereof is 0.001 to 0.8 mg per gram of the carbon-based catalyst. A method for desulfurization of flue gas, characterized in that, while maintaining the surface of the carbon-based catalyst in a wet state, the exhaust gas containing at least sulfurous acid gas, oxygen and moisture is brought into contact with items 1 to 7 of the patent application scope. Any of the carbon-based catalysts. The method of claim 8, wherein the exhaust gas further comprises mercury and simultaneously removes mercury in the exhaust gas. The method of claim 8, wherein the exhaust gas is an outlet gas of the wet flue gas desulfurization device. The method of claim 10, wherein the wet state is maintained by continuously or intermittently spraying industrial water or a dilute sulfuric acid solution to the carbon-based catalyst, and the outflow from the carbon-based catalyst is performed. The liquid is supplied to the above-described wet flue gas desulfurization device. The method of claim 11, wherein the effluent flowing from the carbon-based catalyst is subjected to adsorption or ion exchange treatment to remove After iodine or bromine, it is supplied to the above-mentioned wet flue gas desulfurization device. The method of claim 8, wherein the molar ratio of oxygen to sulfurous acid gas in the exhaust gas is controlled to be 10 or more by introducing air into the exhaust gas.