TW202041464A - Acidic exhaust gas treatment agent, acidic exhaust gas treatment method, and acidic exhaust gas treatment equipment - Google Patents

Abstract

Provided are an acidic exhaust gas treatment agent, an acidic exhaust gas treatment method, and acidic exhaust gas treatment equipment, with which nitric oxide elimination efficiency can be improved compared to the prior art when using layered double hydroxide to treat acidic exhaust gases generated from combustion facilities such as thermal power plants and incineration facilities. This acidic exhaust gas treatment method comprises: a step (1) of using an acidic exhaust gas treatment agent containing a complex of Mg-Al based layered double hydroxide and manganese oxide and/or a permanganate compound, and bringing the acidic exhaust gas into contact with the acidic exhaust gas treatment agent to cause the acidic substance present in the acidic exhaust gas to become adsorbed thereon; a step (2) of desorbing the acidic substance adsorbed onto the acidic exhaust gas treatment agent in the step (1), to regenerate the acidic exhaust gas treatment agent; and a step (3) of recovering the acidic substance desorbed from the acidic exhaust gas treatment agent in the step (2).

Description

Acid exhaust gas treatment agent, acid exhaust gas treatment method and acid exhaust gas treatment equipment

The present invention relates to an acid exhaust gas treatment agent, an acid exhaust gas treatment method and an acid exhaust gas treatment equipment applied to treat acid exhaust gas generated from combustion facilities such as thermal power stations or incineration facilities.

The combustion exhaust gas generated during thermal power generation or waste incineration contains harmful acidic substances such as hydrogen chloride, sulfur oxides, and nitrogen oxides. Therefore, the acid exhaust gas containing the acid substance is processed by various methods for removing the acid substance.

Regarding the hydrogen chloride or sulfur oxides in the acidic substance, the dry method or the wet method is becoming popular. The dry method uses an alkali agent such as slaked lime for neutralization, and uses a dust collector to collect the product. The wet method It uses scrubbers for neutralization. In addition, for nitrogen oxides, the use of selective catalytic reduction (Selective Catalytic Reduction, SCR) and non-catalytic reduction (Selective Non-Catalytic Reduction, SNCR) treatment is spreading, the selective catalytic reduction method is After mixing a reducing agent such as ammonia or urea in the combustion exhaust gas, it is decomposed into nitrogen and water by carrying vanadium or platinum on a catalyst such as a ceramic carrier. The catalyst-free reduction method is used in an incinerator, etc. Direct spraying of reducing agents such as ammonia or urea to decompose nitrogen oxides.

However, the treatment using the neutralization treatment requires a treatment step of neutralizing the product, and additionally, the nitrogen oxide needs to be treated separately. In addition, in the treatment of nitrogen oxides using SCR or SNCR, there is a problem in that it is necessary to use a reducing agent or a catalyst, and the cost of equipment and energy for this.

In response to such a problem, the inventors of the present invention have proposed a method that can treat the acid exhaust gas efficiently and at a lower cost by using a carbonate-type Mg-Al-based layered double hydroxide (refer to Patent Document 1) . [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-190199

[The problem to be solved by the invention] However, even if the treatment method described in Patent Document 1 is used, the removal treatment of nitric oxide may be insufficient. Therefore, in the treatment of acidic exhaust gas using layered double hydroxide, it is required to improve the removal efficiency of nitric oxide.

The present invention was completed under such circumstances, and its purpose is to provide a method for treating acidic exhaust gas generated from combustion facilities such as thermal power stations or incineration facilities using layered double hydroxides, which can improve by one An acidic exhaust gas treatment agent, an acidic exhaust gas treatment method and an acidic exhaust gas treatment equipment for the removal efficiency of nitrogen oxides.

[Means to solve the problem] The present invention is based on the discovery that a composite compound formed of manganese oxide or the like of Mg-Al-based layered double hydroxide (hereinafter also referred to as Mg-Al LDH (Layered Double Hydroxide)) has excellent nitric oxide removal performance.

That is, the present invention provides the following [1] to [7]. [1] An acidic exhaust gas treatment agent comprising a composite compound formed of at least one of manganese oxide and permanganate compound of Mg-Al-based layered double hydroxide. [2] The acidic exhaust gas treatment agent described in [1], wherein the composite compound is a manganese dioxide composite Mg-Al-based layered double hydroxide and a permanganic acid type Mg-Al-based layered double hydroxide At least any one of hydroxides. [3] The acidic exhaust gas treatment agent as described in [1] or [2], which contains a carbonated Mg—Al-based layered double hydroxide.

[4] An acid exhaust gas treatment method that uses the acid exhaust gas treatment agent described in any one of [1] to [3] to treat acid exhaust gas, and includes: Step (1) of the exhaust gas being in contact with the acidic exhaust gas treatment agent to adsorb acidic substances in the acidic exhaust gas; and removing the acidic substances adsorbed on the acidic exhaust gas treatment agent in the step (1) Attaching step (2) of regenerating the acidic exhaust gas treatment agent; and step (3) of recovering the acidic substances desorbed from the acidic exhaust gas treatment agent in the step (2). [5] The acid exhaust gas treatment method described in [4], wherein the treatment cycle including the steps (1) to (3) is repeatedly performed, and at least any time after the second time of the treatment cycle is repeated. In step (1) of one treatment cycle, the acidic exhaust gas treatment agent regenerated in step (2) of at least any treatment cycle before the treatment cycle is used as at least a part of the acidic exhaust gas treatment agent.

[6] An acid exhaust gas treatment facility that uses the acid exhaust gas treatment agent described in any one of [1] to [3] to treat acid exhaust gas, and includes: Unit (1) for the exhaust gas to contact the acidic exhaust gas treatment agent to adsorb the acidic substances in the acidic exhaust gas; to remove the acidic substances adsorbed on the acidic exhaust gas treatment agent in the unit (1) Attached is a unit (2) that regenerates the acidic exhaust gas treatment agent; and a unit (3) that recovers acidic substances desorbed from the acidic exhaust gas treatment agent in the unit (2). [7] The acid exhaust gas treatment method described in [4], wherein the manganese dioxide composite Mg-Al layered double hydroxide is made by adding Mg-Al oxide to an aqueous potassium permanganate solution , The precipitate is filtered and dried to produce a method that does not require a reduction step.

[Effects of the invention] By using the acidic exhaust gas treatment agent of the present invention, it is possible to simultaneously remove acidic exhaust gas such as hydrogen chloride, sulfur oxides, and nitrogen oxides generated from combustion facilities such as thermal power stations or incineration facilities, especially nitrogen monoxide. The removal efficiency is higher than that of the conventional layered double hydroxide. In addition, according to the acid exhaust gas treatment method of the present invention using the acid exhaust gas treatment agent, acid exhaust gas can be efficiently removed with a smaller treatment amount than in the past, and the acid exhaust gas treatment agent can be recycled . In addition, according to the acid exhaust gas treatment device of the present invention, the acid exhaust gas treatment method can be suitably performed, and acid exhaust gas can be treated more efficiently and at low cost than in the past.

Hereinafter, the acid exhaust gas treatment agent of the present invention, the acid exhaust gas treatment method and the acid exhaust gas treatment equipment using the same will be described in detail.

[Acid exhaust treatment agent] The acidic exhaust gas treatment agent of the present invention contains a composite compound of Mg-Al LDH composed of at least one of manganese oxide and permanganate compound (hereinafter, also referred to as Mn-O compound). As mentioned above, by using Mg-Al LDH as a composite compound of manganese and oxygen compound (Mn-O compound) as an acidic exhaust gas treatment agent, it is different from the conventional layered double hydroxide. Compared with the case of Mg-Al LDH, it can improve the removal efficiency of nitric oxide. It is presumed that the reason is that although Mg-Al LDH itself is difficult to adsorb nitric oxide, it is oxidized to nitrogen dioxide by the catalytic action of the composite Mn-O compound, and then easily oxidized to nitrate. Ions, which are easily adsorbed to the Mg-Al LDH complex compound.

Manganese may have an oxidation number of +2 to +7, and from the viewpoint of its function as an oxidation catalyst, it is preferably one with a larger oxidation number. As the composite compound, from the viewpoint of ease of synthesis and the like, for example, a manganese dioxide composite Mg-Al layered double hydroxide (hereinafter, also referred to as MnO ₂ composite) formed of manganese with oxidation number +4 Mg-Al LDH) or permanganic acid type Mg-Al layered double hydroxide formed of manganese with oxidation number +7 (hereinafter, also referred to as MnO ₄ type Mg-Al LDH). The composite compound may be one kind alone or two or more kinds.

The structural formula of the MnO ₂ composite Mg-Al LDH is represented by the following formula (1), and the structural formula of the MnO ₄ type Mg-Al LDH is represented by the following formula (2). Mg _1-xAlx( OH) ₂ (MnO ₂ ) _2.5x (Cl) _x ·mH ₂ O (1) Mg _1-xAlx( OH) ₂ (MnO ₄ ) _x ·mH ₂ O (2) In the formula ( 1) and formula (2), usually x=0.20～0.40, m=1～12.

The acidic exhaust gas treatment agent preferably contains carbonic acid type Mg—Al layered double hydroxide (hereinafter, also referred to as CO ₃ type Mg—Al LDH). As described in Patent Document 1, the CO ₃ type Mg-Al LDH is a compound that can be suitably used to treat acid exhaust gas, and can efficiently remove, for example, hydrogen chloride, sulfur dioxide, and nitrogen dioxide contained in acid exhaust gas. Acidic compounds other than nitric oxide. Therefore, it is preferably used in combination with the composite compound. In this case, the ratio of the content of the composite compound in the acid exhaust gas treatment agent to the content of CO ₃ type Mg-Al LDH is not particularly limited, and may be based on the nitrogen monoxide contained in the acid exhaust gas to be treated. The amount of acid exhaust gas and the composition of the acid exhaust are appropriately set.

CO ₃ type Mg-Al LDH as hydrotalcite, there are naturally occurring clay minerals, but in the case of synthesis, the synthesis method is not particularly limited, and a known method can be used (for example, in the patent document 1 Documented method). For example, it can be obtained as follows: an aqueous solution of magnesium nitrate (Mg(NO ₃ ) ₂ ) and aluminum nitrate (Al(NO ₃ ) ₃ ) mixed with Mg/Al=2/1 (molar ratio) Keep the pH at 10.5, while adding dropwise to the sodium carbonate (Na ₂ CO ₃ ) aqueous solution. Specifically, it can be synthesized by the method shown in the following examples.

In addition, the synthesis method of MnO ₂ composite Mg-Al LDH and MnO ₄ type Mg-Al LDH is not particularly limited. CO ₃ type Mg-Al LDH can be used as a raw material compound to utilize the anion exchange function brought by its intercalation And synthesize. For example, after sintering CO ₃ type Mg-Al LDH at 500°C to obtain Mg-Al oxide, it is added and mixed with potassium permanganate (KMnO ₄ ) aqueous solution, thereby synthesizing and taking in permanganate ion (MnO ₄ ^-) MnO ₄ type Mg-Al LDH. Furthermore, MnO ₄ type Mg-Al LDH is changed into MnO ₂ composite Mg-Al LDH in a potassium permanganate (KMnO ₄ ) aqueous solution. In addition, the MnO ₄ type Mg-Al LDH can be added and mixed in a manganese chloride (MnCl ₂ ) aqueous solution to synthesize MnO ₂ composite Mg-Al LDH.

The acidic exhaust gas treatment agent may include, for example, calcium hydroxide (slaked lime), calcium oxide, sodium bicarbonate, sodium carbonate, hydroxide dolomite, and light burned dolomite within a range that does not hinder the effects of the present invention. Agents other than layered double hydroxides such as stone, aluminum hydroxide, aluminum oxide, magnesium hydroxide, and magnesium oxide. Among them, in the acid exhaust gas treatment method described later, in the case of regenerating the acid exhaust gas treatment agent and supplying it for reuse, it is preferable to not contain any from the viewpoint of the purity of the regenerated product or the recovery operation. These medicines.

[Acid exhaust gas treatment method] The method of using the acid exhaust gas treatment agent to treat acid exhaust gas is not particularly limited. The acid exhaust gas treatment agent (hereinafter, also referred to as the treatment agent for short) is preferably applied to the acid exhaust gas treatment method of the present invention . The acid exhaust gas treatment method of the present invention is a treatment method including the steps of: contacting acid exhaust gas with the treatment agent to adsorb acidic substances in the acid exhaust gas (1); Step (2) of desorbing the acidic substance adsorbed on the treatment agent to regenerate the treatment agent in ); and step (3) of recovering the acidic substance desorbed from the treatment agent in the step (2) . According to the treatment method described above, the regenerated treatment agent can be reused. In addition, the acidic substance is, for example, dissolved in water and recovered in the form of an acid (aqueous solution), and the acid can also be utilized in industrial applications and the like.

In the step (1), nitric oxide is oxidized by the complex compound in the treatment agent, and the acidic substance in the acid exhaust is taken in between the layers of the layered double hydroxide. Anion exchange, etc., the acidic substance is adsorbed on the treatment agent.

Then, in the step (2), the acidic substance adsorbed on the treatment agent is desorbed from the treatment agent by reversible anion exchange or the like. The anion exchange at this time can be performed, for example, by using various aqueous solutions and mixing and stirring them in the same way as the synthesis method of CO ₃ type Mg-Al LDH, MnO ₂ composite Mg-Al LDH and MnO ₄ type Mg-Al LDH. The treatment agent can be easily regenerated. The treatment agent regenerated in this way can be reused, so the treatment cost of acid exhaust gas can be reduced.

In the step (3), the acidic substance desorbed from the treatment agent in the step (2) is recovered. For example, it can be dissolved in water and recovered in the form of an acid (aqueous solution), and the acid can also be used in industrial applications. As described above, the treatment method of the present invention is not only for the treatment agent, but also for the acid exhaust gas that is the treatment target, and is also a method having excellent recirculation properties.

In the treatment method, it is preferable to repeatedly perform the treatment cycle including the steps (1) to (3), and in step (1) of at least any treatment cycle after the second time of the treatment cycle , The treatment agent regenerated in step (2) of at least any treatment cycle before the treatment cycle is used as at least a part of the treatment agent. As described above, when the treatment method is repeatedly performed, by reusing the treatment agent regenerated in the previous step, the total usage of the treatment agent required for the treatment of acid exhaust gas can be reduced, and the acidity will also be reduced. The cost of exhaust gas treatment.

As described above, the acid exhaust gas treatment method of the present invention can simultaneously remove various acidic substances in the acid exhaust gas using one treatment agent, and therefore has excellent work efficiency. In particular, by using the composite compound as a treatment agent, the removal efficiency of nitric oxide can be improved compared to the past. In addition, no neutralized product is generated during processing, and the processing load of waste generated with processing can be reduced.

[Sour exhaust gas treatment equipment] The equipment for treating acid exhaust gas using the acid exhaust gas treatment agent is not particularly limited, and the treatment agent is preferably applied to the acid exhaust gas treatment equipment of the present invention. The acid exhaust gas treatment equipment of the present invention is a treatment equipment including a unit (1) that makes acid exhaust gas contact with the treatment agent to adsorb acidic substances in the acid exhaust gas; Unit (2) for desorbing the acidic substance adsorbed on the treatment agent to regenerate the treatment agent; and unit (3) for recovering the acidic substance desorbed from the treatment agent in the unit (2) .

The unit (1) can be configured by, for example, providing a flow path of acid exhaust gas in a container containing the processing agent. The unit (2) may be configured as, for example, a dipping tank: for the treatment agent taken out of the container after self-circulating acid exhaust gas, by combining Mg-Al with the CO ₃ type Mg-Al LDH, MnO ₂ The synthesis method of LDH and MnO ₄ type Mg-Al LDH is the same, according to the chemical species that is compounded into Mg-Al LDH, immersed in various aqueous solutions and mixed and stirred. The unit (3) may be configured as an aqueous solution storage tank that is dissolved in water and recovered as an acid (aqueous solution), for example.

The acid exhaust gas treatment equipment may be attached to combustion equipment such as thermal power generation or waste incineration. For example, in the case of processing acid exhaust gas generated in a waste incinerator, it can be configured to install the acid exhaust gas after the boiler, exhaust gas cooling device, and dust collector are installed in the combustion exhaust system of the incinerator body. The exhaust gas processing equipment is used to introduce the processed exhaust gas from the acid exhaust gas processing equipment into the chimney using an induction ventilator or the like, and the exhaust gas is released from the chimney into the atmosphere. [Example]

Hereinafter, the present invention will be described in further detail, but the present invention is not limited by the following examples.

[Synthesis example 1] The synthesis of MnO ₂ composite Mg-Al LDH uses magnesium nitrate hexahydrate and aluminum nitrate nonahydrate to prepare a mixed aqueous solution (magnesium/aluminum) with a magnesium concentration of 0.33 mol/L and an aluminum concentration of 0.17 mol/L = 2/1 (mole ratio)). At 30°C, the mixed solution was added dropwise to a sodium carbonate aqueous solution with a concentration of 0.1 mol/L while stirring the mixed solution. At this time, the pH value was maintained at 10.5 by dropping a sodium hydroxide aqueous solution with a concentration of 1.25 mol/L. After the dropwise addition, it was stirred at 30°C for 1 hour. After that, the precipitate was filtered, washed repeatedly, and dried under reduced pressure at 40°C for 40 hours to obtain CO ₃ type Mg-Al LDH. After the obtained CO ₃ type Mg-Al LDH was sintered at 500°C for 2 hours, it was poured into a 0.2 mol/L potassium permanganate aqueous solution under a nitrogen stream, and stirred at 30°C for 6 hours. After that, the precipitate was filtered, and after repeated washing, the product obtained by drying under reduced pressure at 40°C for 40 hours was poured into an aqueous solution of manganese chloride with a concentration of 0.1 mol/L under a nitrogen gas stream at 30°C Stir for 3 hours. After that, the precipitate was filtered, washed repeatedly, and dried under reduced pressure at 40°C to obtain MnO ₂ composite Mg-Al LDH (Mg _0.62 Al _0.38 (OH) ₂ (MnO ₂ ) _0.95 (Cl) _0.38 ·1.13 H ₂ O).

[Synthesis example 2] Synthesis of MnO ₂ composite Mg-Al LDH Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate were used to prepare a mixed aqueous solution (magnesium/aluminum) with a magnesium concentration of 0.33 mol/L and an aluminum concentration of 0.17 mol/L = 2/1 (mole ratio)). At 30°C, the mixed solution was added dropwise to a sodium carbonate aqueous solution with a concentration of 0.1 mol/L while stirring the mixed solution. At this time, the pH value was maintained at 10.5 by dropping a sodium hydroxide aqueous solution with a concentration of 1.25 mol/L. After the dropwise addition, it was stirred at 30°C for 1 hour. After that, the precipitate was filtered, washed repeatedly, and dried under reduced pressure at 40°C for 40 hours to obtain CO ₃ type Mg-Al LDH. After the obtained CO ₃ type Mg-Al LDH was sintered at 500°C for 2 hours, it was poured into a 0.2 mol/L potassium permanganate aqueous solution under a nitrogen stream, and stirred at 30°C for 6 hours. Thereafter, the precipitate was filtered, washed repeatedly, and dried under reduced pressure at 40°C for 40 hours.

Furthermore, the CO ₃ type Mg-Al LDH, MnO ₄ type Mg-Al LDH, and MnO ₂ composite Mg-Al LDH in Synthesis Example 1 and Synthesis Example 2 were measured by powder X-ray diffraction measurement (powder XRD) Phase identification. Regarding the CO ₃ type Mg-Al LDH, the powder X-ray diffraction diagram is shown in FIG. 4. In addition, the X-ray diffraction measurement device used was "RINT-2200VHF" manufactured by Rigaku Co., Ltd., and CuKα rays (1.5418A) were used as characteristic X-rays for measurement. In addition, regarding the composite compound formed of the Mn-O compound, the elemental analysis value obtained by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) is also shown. In addition, the MnO ₄ type Mg-Al LDH and the MnO ₂ composite Mg-Al LDH in Synthesis Example 1 and Synthesis Example 2 were identified by specifying the oxidation number of Mn using X-ray photoelectron spectroscopy (XPS).

[Acid exhaust gas treatment performance evaluation test] (Example 1) 1.0 g of the MnO ₂ composite Mg-Al LDH obtained in Synthesis Example 1 was filled on the glass wool in the reaction tube (inner diameter 16 mm) of the tubular electric furnace . Set the set temperature of the tubular electric furnace to 170℃, use the mass flow controller to adjust the flow rate of the test gas (carrier gas: nitrogen, nitric oxide gas concentration 150 volppm, oxygen concentration 10 vol%) at a linear velocity of 1.0 m/min Flow into the reaction tube. By using a constant potential electrolysis of the combustion exhaust gas analyzer (Taisite (TEST) Co., Ltd.) to determine the change over time of _the NO _x concentration in the outlet gas of the reaction tube (90 minutes).

(Comparative Example 1) In Example 1, the MnO ₂ composite Mg-Al LDH was changed to the CO ₃ type Mg-Al LDH obtained in the synthesis process of Synthesis Example 1, except that it was performed in the same manner as Example 1 Evaluation test.

The change chart when the NO _x concentration in the outlet gas of the reaction tube in Example 1 and Comparative Example 1 by 1 and shown in FIG. In addition, the reaction rate of the nitric oxide gas in the test gas was calculated from the cumulative concentration of the NO _x concentration. As a result, Example 1 was 91.5 vol%, and Comparative Example 1 was 2.2 vol%. From these results, it was confirmed that the composite compound of manganese dioxide and Mg-Al-based layered double hydroxide is superior to CO ₃ type Mg-Al LDH in removing nitric oxide.

[Analysis of the abundance ratio of MnO ₂ composite Mg-Al LDH obtained in Synthesis Example 1 and Synthesis Example 2] The powder X-ray diffraction diagrams of the products obtained in Synthesis Example 1 and Synthesis Example 2 are shown in FIGS. 2 and 3 . In addition, the XPS spectra of the products obtained in Synthesis Example 1 and Synthesis Example 2 are shown in FIGS. 5 and 6. According to the elemental analysis values, the Mg/Al molar ratios of the products of Synthesis Example 1 and Synthesis Example 2 are 1.9 and 1.6, respectively, which are roughly consistent with the initial Mg/Al molar ratio of 2.0. According to the powder X-ray diffraction diagrams of Figures 2 and 3, both show the X-ray peaks attributed to LDH, and the interplanar spacing (d ₀₀₃ ) is also 7.6 Å and 7.5 Å, and the LDH structure is confirmed for either product. From the XPS spectra of FIGS. 5 and 6, the peak of Mn(IV) derived from MnO ₂ was confirmed, and from the peak area, it was confirmed that 95% or more of Mn(IV) was present relative to the total amount of Mn. From these results, it was confirmed that even if there is no reduction step in the manganese chloride aqueous solution shown in Synthesis Example 1, as in Synthesis Example 2, MnO ₂ composite Mg-Al LDH can be synthesized.

Furthermore, it is considered that in Synthesis Example 2, the MnO ₂ composite Mg-Al LDH is produced as follows. First, the CO ₃ type Mg-Al LDH is sintered at 500°C for 2 hours, and then the generated Mg-Al oxide (Mg _1-x Al _x O _1+x/2 ) is charged to a concentration of 0.2 under nitrogen flow Mole/L potassium permanganate aqueous solution, after stirring at 30℃ for 6 hours, as shown in formula (3), MnO ₄ type Mg-Al LDH (Mg _1-x Al _x (OH) ₂ (MnO ₄ ) _x ). _{Mg 1-x Al x O 1} + x / 2 + xMnO 4 - + (1 + x / 2) H 2 O → Mg 1-x Al x (OH) 2 (MnO 4) x + xOH - (3) Further , In the potassium permanganate aqueous solution, the reaction shown in formula (4) occurs, thereby generating MnO ₂ type Mg-Al LDH (Mg _1-x Al _x (OH) ₂ (MnO ₂ ) _x ). _{Mg 1-xAlx (OH) 2} (MnO 4) x + x / 2H 2 O → Mg 1-x Al x (OH) 2 (MnO 2) x + 3 / 4xO 2 + xOH - (4)

no

FIG. 1 is a graph showing change over time of _the NO _x concentration of the acidic gas outlet of the reaction tube an exhaust gas treatment performance evaluation tests by the embodiment. 2 is a powder X-ray diffraction diagram of the product of Synthesis Example 1. FIG. 3 is a powder X-ray diffraction diagram of the product of Synthesis Example 2. FIG. Fig. 4 is a powder X-ray diffraction diagram of CO ₃ type Mg-Al LDH. FIG. 5 is an X-ray photoelectric spectrophotometry (XPS) spectrum of the product of Synthesis Example 1. FIG. Fig. 6 is an XPS spectrum of the product of Synthesis Example 2.

Claims (7)

An acidic exhaust gas treatment agent comprising a composite compound formed of at least one of manganese oxide and permanganate compound of Mg-Al-based layered double hydroxide. The acidic exhaust gas treatment agent according to claim 1, wherein the composite compound is at least one of manganese dioxide composite Mg-Al layered double hydroxide and permanganic acid type Mg-Al layered double hydroxide Either. The acidic exhaust gas treatment agent according to claim 1 or 2, which contains a carbonate-type Mg-Al-based layered double hydroxide. An acid exhaust gas treatment method, which is a method for treating acid exhaust gas using the acid exhaust gas treatment agent as described in any one of claim 1 to claim 3, and includes: Step (1) of contacting the acidic exhaust gas with the acidic exhaust gas treatment agent to adsorb acidic substances in the acidic exhaust gas; Step (2) of desorbing the acidic substance adsorbed on the acidic exhaust gas treatment agent in the step (1) to regenerate the acidic exhaust gas treatment agent; and The step (3) of recovering the acidic substances desorbed from the acidic exhaust gas treatment agent in the step (2). The acid exhaust gas treatment method according to claim 4, wherein the treatment cycle including the steps (1) to (3) is repeatedly performed, and the steps of at least any treatment cycle after the second time of the treatment cycle are repeated In (1), the acidic exhaust gas treatment agent regenerated in step (2) of at least any one of the treatment cycles before the treatment cycle is used as at least a part of the acidic exhaust gas treatment agent. An acid exhaust gas treatment equipment, which is an equipment that uses the acid exhaust gas treatment agent according to any one of claim 1 to claim 3 to treat acid exhaust gas, and includes: Unit (1) for contacting the acid exhaust gas with the acid exhaust gas treatment agent to adsorb acid substances in the acid exhaust gas; A unit (2) for desorbing the acidic substance adsorbed on the acidic exhaust gas treatment agent in the unit (1) to regenerate the acidic exhaust gas treatment agent; and A unit (3) for recovering acidic substances desorbed from the acidic exhaust gas treatment agent in the unit (2). The acid exhaust gas treatment method according to claim 4, wherein the manganese dioxide composite Mg-Al-based layered double hydroxide is performed by adding Mg-Al oxide to the potassium permanganate aqueous solution to perform the precipitation Filtered and dried to produce a production method that does not require a reduction step.

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