Acid gas absorbent, method for removing acid gas, and acid gas removal apparatus

Abstract

To provide an amine compound with a high capacity for acidic gas absorption and high oxidation resistance, an absorbent comprising the same, and a method for removing acid gas, and an acid gas removal apparatus.SOLUTION: The present invention provides an acid gas absorbent that comprises an amine compound having either formula (a1) or only one side chain of formula (a1), as well as an acid gas removal method and apparatus using the absorbent [where R1 and R2 independently represent hydrogen or an alkyl group; among R2 included in one -CR23, at least two are not hydrogen; p independently represents 0 or 1; m represents a number of 1-3; and n independently represents a number of 1-4].SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an acid gas absorbent, a method for removing acid gas, and an apparatus for removing acid gas. [Background technology]

[0002] In recent years, the greenhouse effect caused by rising carbon dioxide (CO2) concentrations has been pointed out as one of the causes of global warming, and international measures to protect the environment on a global scale are urgently needed. CO2 is generated largely through industrial activities, and there is a growing momentum to reduce its emissions into the environment.

[0003] Technologies for preventing the increase in the concentration of acid gases, including CO2, include the development of energy-saving products, technologies for using acid gases as resources or for isolating and storing them, and a shift to alternative energy sources such as natural energy and nuclear energy that do not emit acid gases. One well-known example is the technology for separating and capturing acid gases that are emitted.

[0004] The techniques for separating acidic gases that have been researched to date include absorption, adsorption, membrane separation, and cryogenic methods. Among these, the absorption method is economical and suitable for efficiently treating large amounts of gas, and because it is easy to scale up the removal equipment, it is being considered for application to factories and power plants.

[0005] As a method mainly targeted at thermal power plants that use fossil fuels, a method is known in which the exhaust gas generated when burning fossil fuels (coal, oil, natural gas, etc.) is brought into contact with a chemical absorbent to remove and capture the CO2 in the combustion exhaust gas, and then the captured CO2 is stored. It has also been proposed to use chemical absorbents to remove acid gases such as hydrogen sulfide (H2S) in addition to CO2.

[0006] Generally, alkanolamines, such as monoethanolamine (MEA), are known as chemical absorbents used in the absorption method. Such alkanolamines have been developed since the 1930s and are still in use today. Common alkanolamines used in the absorption method include 2-amino-2-methylpropanolamine, methylaminoethanol, ethylaminoethanol, propylaminoethanol, diethanolamine, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, and dimethylamino-1-methylethanol.

[0007] When these conventionally used alkanolamines are used alone, the CO2 absorption rate may not be sufficient. Even if the amine compound has a large CO2 absorption capacity, if the CO2 absorption rate is slow, the contact time between the acid gas absorbent and the exhaust gas must be extended, resulting in poor treatment efficiency. From this perspective, studies have been conducted to improve the CO2 absorption rate, such as the use of a compound with a reaction promotion effect. From this perspective, a new absorbent with a higher absorption rate for acid gases such as CO2 is required. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2006-518662 [Non-patent literature]

[0009] [Non-Patent Document 1] Alexander K. Boyce et al., Energy Procedia 37(2013)2118-2132 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present embodiment is to provide an acid gas absorbent having an improved absorption rate of acid gas, and a method for removing acid gas using the same, and an apparatus for removing acid gas. [Means for solving the problem]

[0011] The embodiments provided by the present invention are as follows. [1] (A) Formula (a1) or Formula (a2): [ka] [In the formula, R 1 each independently represents a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms; R 2 are each independently a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms, 2 R included in 3 2 at least two of which are not hydrogen; R 3 is an unsubstituted or substituted alkyl group having up to 4 carbon atoms, Each p is independently 0 or 1; m is a number from 1 to 3; and each n is independently a number from 1 to 4. A first amine compound represented by the formula: (B) Formula (b): [ka] [In the formula, R 4 are each independently hydrogen or an unsubstituted or substituted alkyl group; 4 At least one of the R 4 may form a cyclic structure in which and a second amine compound represented by (C) Solvent The ratio B / A of the content of the (B) component to the content of the (A) component is 2.5 to 15. , an acid gas absorbent. [2] The acidic gas absorbent according to [1], wherein the ratio B / A is 3 to 12. [3] The acidic gas absorbent according to [1] or [2], wherein n is 2 or 3. [4] The acidic gas absorbent according to any one of [1] to [3], wherein the m is 2. [5] The acidic gas absorbent according to any one of [1] to [4], wherein all of the p's are 1. [6] The acidic gas absorbent according to any one of [1] to [5], wherein the content of component (A) is 3 to 20 mass % based on the total amount of the acidic gas absorbent. [7] The acidic gas absorbent according to any one of [1] to [6], further comprising an additive selected from the group consisting of an antioxidant, a pH adjuster, an antifoaming agent, and an anticorrosive agent. [8] A method for removing an acidic gas, comprising contacting a gas containing an acidic gas with the acidic gas absorbent according to any one of [1] to [7], and removing the acidic gas from the gas containing an acidic gas. [9] an absorber for removing the acid gas from the gas containing the acid gas by contacting the gas with the acid gas absorbent according to any one of [1] to [7] and causing the acid gas to be absorbed by the acid gas absorbent; a regenerator for desorbing the acid gas from the acid gas absorbent that has absorbed the acid gas, and regenerating the acid gas absorbent; having The acid gas absorbent regenerated in the regenerator is reused in the absorber. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an acid gas removal apparatus according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described in detail. In the following embodiments, the case where the acidic gas is carbon dioxide will be described as an example, but the acidic gas absorbent according to the embodiment of the present invention can obtain the same effect with respect to other acidic gases such as hydrogen sulfide. The acidic gas absorbent according to the embodiment is particularly suitable for absorbing oxidizing gases such as carbon dioxide and hydrogen sulfide.

[0014] The acidic gas absorbent according to the embodiment includes a specific combination of amine compounds and a solvent. Here, the combination of amine compounds is a combination of (A) a first amine compound and (B) a second amine compound, which will be described below.

[0015] <(A) First Amine Compound> The acidic gas absorbent according to the embodiment includes a first amine compound (hereinafter, sometimes referred to as component (A)) having a specific structure. The component (A) is a diamine compound having a specific structure. One of the cyclic diamine compounds that can be used in the embodiment is represented by formula (a1). [ka] [In the formula, R 1 each independently represents a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms; R 2 are each independently a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms, 2 R included in 3 2 at least two of which are not hydrogen; Each p is independently 0 or 1; m is a number from 1 to 3; and each n is independently a number from 1 to 4.

[0016] More specifically, R 1 is hydrogen, methyl, ethyl, propyl, or isopropyl; R 2is hydrogen, a methyl group, or an ethyl group, n is an integer of 1 to 4, preferably 2 or 3, and m is an integer of 1 to 3, preferably 2. Specific examples of such amine compounds represented by formula (a1) include the following.

[0017] [ka]

[0018] [ka]

[0019] Another example of the component (A) that can be used in the acidic gas absorbent according to the embodiment is represented by formula (a2).

[0020] [ka] [In the formula, R 1 each independently represents a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms; R 2 are each independently a hydrogen atom or an unsubstituted or substituted alkyl group having 3 or less carbon atoms, 2 R included in 3 2 at least two of which are not hydrogen; R 3 is an unsubstituted or substituted alkyl group having up to 4 carbon atoms, Each p is independently 0 or 1; m is a number from 1 to 3; and each n is independently a number from 1 to 4.

[0021] More specifically, R 1 is hydrogen, methyl, ethyl, n-propyl, or isopropyl; R 2 is hydrogen, a methyl group, or an ethyl group, and R 1is hydrogen, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, n is an integer of 1 to 4, preferably 2 or 3, and m is an integer of 1 to 3, preferably 2.

[0022] Specific examples of such amine compounds represented by formula (a2) include the following.

[0023] [ka]

[0024] [ka]

[0025] The acidic gas absorbent according to the embodiment contains either formula (a1) or (a2) as the component (A). Here, two or more types of compounds represented by formula (a1) may be combined, two or more types of compounds represented by formula (a2) may be combined, and further, compounds of formula (a1) and formula (a2) may be combined. The method for producing the compound of formula (a1) or (a2) will be described later, and in the production process, a mixture in which p in the formula is 1 and p in the formula is 0 may be mixed. In such a case, the mixture may be used as it is in the acidic gas absorbent according to the embodiment without separating the mixture.

[0026] <(B) Second Amine Compound> The acidic gas absorbent according to the embodiment contains, in addition to the component (A), a second amine compound represented by the following formula (b) (hereinafter, sometimes referred to as component (B)).

[0027] [ka] [In the formula, R 4 are each independently hydrogen or an unsubstituted or substituted alkyl group; 4 At least one of the R4 may form a cyclic structure in which

[0028] R 4 Specific examples of R include hydrogen, methyl, ethyl, isopropyl, tert-butyl, sec-butyl, hydroxyethyl, hydroxypropyl, hydroxypentyl, hydroxyhexyl, hydroxyheptyl, hydroxyoctyl, aminopropyl, aminopentyl, aminohexyl, aminoheptyl, and aminothioctyl. 4 can also be linked to each other to form a piperazine ring, a pyrrolidine ring, a morpholine ring, a piperidine ring, or the like.

[0029] Specific examples of the amine compound represented by formula (b) include: 1-(2-hydroxyethyl)piperazine (HEPZ), 1-(2-aminoethyl)piperazine (AEPZ), 1-(2-isopropylaminoethyl)piperazine (IPAEPZ), 1,4-bis[3-aminopropyl]piperazine, N-isopropyldiethanolamine, N-isopropyldipropanolamine, N-isopropyldibutanolamine, N-isopropyldipentanolamine, N-isopropyldihexanolamine, 3-[(2-hydroxyethyl)(propan-2-yl)amino]propan-1-ol, 4-[(2-hydroxyethyl)(propan-2-yl)amino]butan-1-ol, 5-[(2-hydroxyethyl)(propan-2-yl)amino]pentan-1-ol, 6-[(2-hydroxyethyl)(propan-2-yl)amino]hexan-1-ol, N-sec-butyldiethanolamine, N-sec-butyldipropanolamine, N-sec-butyldibutanolamine, N-sec-butyldipentanolamine, N-sec-butyldihexanolamine, 3-[(2-hydroxyethyl)(butan-2-yl)amino]propan-1-ol, 4-[(2-hydroxyethyl)(butan-2-yl)amino]butan-1-ol, 5-[(2-hydroxyethyl)(butan-2-yl)amino]pentan-1-ol, 6-[(2-hydroxyethyl)(butan-2-yl)amino]hexan-1-ol, N-cyclopentyldiethanolamine, N-cyclopentyldipropanolamine, N-cyclopentyldibutanolamine, N-cyclopentyldipentanolamine, N-cyclopentyldihexanolamine, 3-[(2-hydroxyethyl)(cyclopentyl)amino]propan-1-ol, 4-[(2-hydroxyethyl)(cyclopentyl)amino]butan-1-ol, 5-[(2-hydroxyethyl)(cyclopentyl)amino]pentan-1-ol, 6-[(2-hydroxyethyl)(cyclopentyl)amino]hexan-1-ol, 2-azetidinemethanol, 2-(2-aminoethyl)azetidine, 2-pyrrolidinemethanol, 2-(2-aminoethyl)pyrrolidine, 2-Piperidinemethanol, 3-Piperidineethanol, 2-(2-aminoethyl)pyrrolidine, 2-(hydroxymethyl)piperazine, 3-hydroxypyrrolidine, 3-pyrrolidinemethanol, 2-(2-hydroxyethyl)pyrrolidine, 4-Piperidineethanol, 3-hydroxypiperidine, 4-hydroxypiperidine, 4-(hydroxymethyl)piperidine, and 3-Aminopiperidine However, the additional amine compound is not limited to these.

[0030] Of these, 1-(2-hydroxyethyl)piperazine, 1-(2-aminoethyl)piperazine, 1,4-bis[3-aminopropyl]piperazine, N-isopropyldiethanolamine, N-isopropyldipropanolamine, 3-[(2-hydroxyethyl)(propan-2-yl)amino]propan-1-ol, N-sec-butyldiethanolamine, N-sec-butyldipropanolamine, N-sec-butyldibutanolamine, 3-[(2-hydroxyethyl)(butan-2-yl)amino]propan-1-ol, N-cyclopentyldiethanolamine, N-cyclopentyldipropanolamine, and 3-[(2-hydroxyethyl)(cyclopentyl)amino]propan-1-ol, is preferred.

[0031] <Amine compound blend ratio> The acidic gas absorbent according to the embodiment contains the above-mentioned (A) and (B) components, and one of its features is the blending ratio. Specifically, in the acidic gas absorbent according to the embodiment, the ratio B / A of the content of the (B) component to the content of the (A) component is 2.5 to 15, thereby realizing an excellent absorption rate of acidic gases such as carbon dioxide. If the ratio B / A is 3 to 12, the absorption rate of acidic gases is further improved, and therefore it is preferable. The ratio B / A is more preferably 5 to 12, and particularly preferably 6 to 12.

[0032] The content of the (A) component in the acidic gas absorbent according to the embodiment is preferably 3 to 20 mass %, more preferably 3 to 12 mass %, based on the total mass of the acidic gas absorbent. The content of the (B) component is determined by the content of the (A) component and the ratio B / A, and the content of the (B) component in the acidic gas absorbent according to the embodiment is generally 20 to 60 mass %, more preferably 25 to 50 mass %.

[0033] The total content of the components (A) and (B) in the acidic gas absorbent is preferably 10 to 60 mass %, and more preferably 20 to 60 mass %.

[0034] In general, a higher total content of the amine compounds is preferable in terms of energy consumption and treatment efficiency because the amount of carbon dioxide absorbed and desorbed per unit volume is larger and the carbon dioxide absorption and desorption rates are faster. On the other hand, in order to prevent an increase in the viscosity of the acid gas absorbent and to improve its oxidation resistance, it is preferable that the total content of the amine compounds is equal to or less than a certain level.

[0035] <(C) Solvent> The acidic gas absorbent according to the embodiment contains a solvent in addition to the (A) component and the (B) component, and the amine compound is dissolved or dispersed therein. As the solvent, water, an organic solvent, or a mixed solvent thereof, for example, an aqueous solvent, can be used. From the viewpoint of safety and cost, it is preferable to use water or an aqueous solvent as the solvent. However, in order to improve the solubility of the amine compound, etc., an organic solvent or a mixed solvent having a relatively large content of an organic solvent can also be used. The aqueous solvent mainly contains water and a small amount of an organic solvent. However, if the boiling point of the organic solvent is low, it may volatilize in the acidic gas absorption device and cause damage to the device. For this reason, the organic solvent is the boiling point of water, i.e., 100°C or higher. When water is used as the solvent, the content is preferably 40 to 90 mass%, particularly preferably 50 to 80 mass%, based on the total mass of the acidic gas absorbent. When the water content is within this range, it is preferable in terms of suppressing an increase in the viscosity of the absorbent and suppressing foaming when absorbing carbon dioxide. The aqueous solvent contains a small amount of an organic solvent, and the content thereof is preferably 1% by mass or less based on the acidic gas absorbent.

[0036] <(D) Additives> The acid gas absorbent according to the embodiment may further include, as optional components, additives such as, for example, an antioxidant, a pH adjuster, a defoamer, and an anticorrosive agent.

[0037] Preferable specific examples of the antioxidant include dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), sodium erythorbate, sodium nitrite, sulfur dioxide, 2-mercaptoimidazole, 2-mercaptobenzimidazole, etc. When an antioxidant is used, the content based on the total mass of the acidic gas absorbent is preferably 0.01 to 1 mass%, particularly preferably 0.1 to 0.5 mass%.

[0038] The antioxidant can prevent the deterioration of the acidic gas absorbent and improve its life. Preferable specific examples of the defoaming agent include silicone-based defoaming agents and organic defoaming agents. When the defoaming agent is used, the content based on the total mass of the acidic gas absorbent is preferably 0.00001 to 0.001 mass%, particularly preferably 0.0005 to 0.001 mass%. The defoaming agent can prevent foaming of the acidic gas absorbent, suppress a decrease in the absorption efficiency or desorption efficiency of the acidic gas, and prevent a decrease in the fluidity or circulation efficiency of the acidic gas absorbent.

[0039] Preferable specific examples of the anticorrosive agent include phosphate esters, tolyltriazoles, and benzotriazoles. When the anticorrosive agent is used, the content based on the total mass of the acidic gas absorbent is preferably 0.00003 to 0.0008 mass%, particularly preferably 0.00005 to 0.005 mass%. Such an anticorrosive agent can prevent corrosion of plant equipment and extend its life.

[0040] In addition, it is preferable that the acid gas absorbent according to the embodiment does not contain a low boiling point material, specifically a compound having a boiling point of less than 100°C. This is because the acid gas absorbent is heated in the process of removing acid gas or recovering acid gas, and the low boiling point material evaporates and is released into the atmosphere, or the concentration decreases, causing a change in the efficiency of removing acid gas. Specifically, the content of the material having a boiling point of less than 100°C is preferably 1 mass% or less, more preferably 0.1 mass% or less, based on the total mass of the acid gas absorbent.

[0041] As described above, the acidic gas absorbent of the present embodiment can improve the absorption rate of an acidic gas such as carbon dioxide. In addition, since the amine compound (a1) or (a2) has a relatively small diffusibility, the diffusibility tends to be smaller than that of an acidic gas absorbent not containing the amine compound (a1) or (a2).

[0042] <Method of removing acid gas> A method for removing an acid gas according to an embodiment of the present invention comprises contacting a gas containing an acid gas with the first or second acid gas absorbent, and removing the acid gas from the gas containing the acid gas.

[0043] The method for removing acidic gas according to the embodiment of the present invention is basically configured by a step of absorbing an acidic gas into the acidic gas absorbent according to the embodiment of the present invention (absorption step), and a step of desorbing the acidic gas from the acidic gas absorbent according to the embodiment of the present invention that has absorbed the acidic gas. That is, the basic configuration of the method for removing acidic gas according to the embodiment of the present invention includes a step of contacting a gas containing an acidic gas (e.g., exhaust gas, etc.) with the acidic gas absorbent to absorb the acidic gas (acidic gas absorption step), and a step of heating the acidic gas absorbent in which the acidic gas has been absorbed, obtained in the acidic gas absorption step, to desorb and remove the acidic gas (acidic gas separation step).

[0044] The method for contacting a gas containing an acidic gas with an aqueous solution containing the above-mentioned acidic gas absorbent is not particularly limited, and can be, for example, a method in which a gas containing an acidic gas is bubbled through an acidic gas absorbent to cause the absorbent to absorb the acidic gas, a method in which the acidic gas absorbent is dropped in the form of a mist into a gas stream containing the acidic gas (atomization or spray method), or a method in which a gas containing an acidic gas is brought into countercurrent contact with the acidic gas absorbent in an absorber containing a porcelain or metal mesh filler.

[0045] The temperature of the acid gas absorbent when the gas containing the acid gas is absorbed in the aqueous solution is usually preferably from room temperature to 60° C. or less, more preferably 50° C. or less, particularly preferably 20 to 45° C. The lower the temperature, the greater the amount of the acid gas absorbed, but the lower limit of the treatment temperature can be determined depending on the gas temperature in the process, the heat recovery target, etc.

[0046] The pressure during the absorption of acid gas is usually about atmospheric pressure. Although it can be increased to a higher pressure to improve the absorption performance, it is preferable to carry out the process under atmospheric pressure in order to reduce the energy consumption required for compression.

[0047] Methods for separating acid gases from an acid gas absorbent that has absorbed them and recovering pure or high-concentration carbon dioxide include a method of desorbing by heating the acid gas absorbent and bubbling it in a kettle, as in distillation, and a method of expanding the liquid interface and heating it in a plate tower, spray tower, or regeneration tower containing a magnetic or metal mesh packing. This liberates and releases the acid gases from the carbamate anions and bicarbonate ions.

[0048] The temperature of the acidic gas absorbent during separation of the acidic gas is usually 70° C. or higher, preferably 80° C. or higher, and more preferably 90 to 120° C. The higher the temperature, the greater the amount of acidic gas desorbed, but increasing the temperature increases the energy required to heat the absorbent, so the temperature can be determined based on the gas temperature in the process, the heat recovery target, and the like.

[0049] The pressure during separation of acidic gas can usually be about 1 to 3 atmospheres. Although it is possible to reduce the pressure to a lower level in order to improve separation performance, it is preferable to keep the pressure within this range in order to reduce the energy consumption required for pressure reduction. The acidic gas absorbent after separation of the acidic gas can be sent back to the acidic gas absorption process for circulating (recycled)45. In addition, the heat generated during absorption of acidic gas is generally exchanged and cooled in a heat exchanger to preheat the aqueous solution injected into the regenerator in the aqueous solution recycling process.

[0050] The purity of the acid gas thus recovered is usually extremely high, about 95 to 99% by volume. This pure acid gas or high-concentration acid gas can be used as a raw material for the synthesis of chemicals or polymeric substances, a refrigerant for freezing food, etc. In addition, it is also possible to store the recovered acid gas in isolation underground, etc., a technology that is currently being developed.

[0051] Among the above-mentioned steps, the step of separating the acid gas from the acid gas absorbent and regenerating the acid gas absorbent consumes the most energy, and this step may consume about 50 to 80% of the energy of the entire process. Therefore, by reducing the energy consumption in the regeneration step of the acid gas absorbent, the cost of the acid gas absorption and separation step can be reduced, and the acid gas removal from the exhaust gas can be efficiently performed in an economically advantageous manner. According to this embodiment, by using the acid gas absorbent of the above embodiment, the energy required for the acid gas separation (regeneration step) can be reduced. Therefore, the carbon dioxide absorption and separation step can be efficiently performed under economically advantageous conditions.

[0052] In addition, the combination of amine compounds according to the embodiment has improved corrosion prevention properties for metal materials such as carbon steel, compared with the case where an alkanolamine such as 2-aminoethanol, which has been used as an acid gas absorbent, is used alone. Therefore, by using such an acid gas absorbent as a method for removing acid gas, it becomes unnecessary to use high-cost high-grade corrosion-resistant steel, for example, in plant construction, which is advantageous in terms of cost.

[0053] <Acid gas removal equipment> The acid gas removal apparatus according to the embodiment of the present invention includes an absorber that contacts a gas containing an acid gas with the above-mentioned acid gas absorbent, and removes the acid gas from the gas containing an acid gas by absorbing the acid gas into the acid gas absorbent, and a regenerator that desorbs the acid gas from the acid gas absorbent that has absorbed the acid gas, and regenerates the acid gas absorbent, and reuses the acid gas absorbent regenerated by the regenerator in the absorber. Figure 1 is a schematic diagram of the acid gas removal apparatus according to the embodiment.

[0054] This acid gas removal device 1 includes an absorber 2 that brings a gas containing an acid gas (e.g., exhaust gas) into contact with an acid gas absorbent, and absorbs and removes the acid gas from the gas containing the acid gas, and a regenerator 3 that separates the acid gas from the acid gas absorbent that has absorbed the acid gas, and regenerates the acid gas absorbent. Hereinafter, an example will be described in which the acid gas is carbon dioxide.

[0055] FIG. 1 is a schematic diagram of an acidic gas removal apparatus according to an embodiment. This acid gas removal device 1 includes an absorber 2 that brings a gas containing an acid gas (e.g., exhaust gas) into contact with an acid gas absorbent, and absorbs and removes the acid gas from the gas containing the acid gas, and a regenerator 3 that separates the acid gas from the acid gas absorbent that has absorbed the acid gas, and regenerates the acid gas absorbent. Hereinafter, an example will be described in which the acid gas is carbon dioxide.

[0056] As shown in Fig. 1, exhaust gas containing carbon dioxide, such as combustion exhaust gas discharged from a thermal power plant or the like, is introduced to the lower part of the absorber 2 through a gas supply port 4. This exhaust gas is forced into the absorber 2 and comes into contact with an acid gas absorbent supplied from an acid gas absorbent supply port 5 at the upper part of the absorber 2. As the acid gas absorbent, the acid gas absorbent according to the above-mentioned embodiment is used.

[0057] In addition to the above-mentioned amine compound and a solvent such as water, the acidic gas absorbent may contain other compounds in any ratio, such as a nitrogen-containing compound that improves the carbon dioxide absorption performance, an antioxidant, a pH adjuster, etc.

[0058] In this way, the exhaust gas comes into contact with the acid gas absorbent, and carbon dioxide in the exhaust gas is absorbed and removed by the acid gas absorbent. The exhaust gas from which carbon dioxide has been removed is discharged to the outside of the absorber 2 through the gas outlet 6.

[0059] The acidic gas absorbent that has absorbed carbon dioxide is pumped to the heat exchanger 7 by the rich liquid pump 8, and is further pumped to the regenerator 3. The acidic gas absorbent pumped into the regenerator 3 moves from the top to the bottom of the regenerator 3, during which the acidic gas in the acidic gas absorbent is desorbed, and the acidic gas absorbent is regenerated.

[0060] The acidic gas absorbent regenerated in the regenerator 3 is pumped by a lean liquid pump 9 to a heat exchanger 7 and an absorbent cooler 10 , and then returned to the absorber 2 from an acidic gas absorbent supply port 5 .

[0061] On the other hand, the acid gas separated from the acid gas absorbent comes into contact with reflux water supplied from the reflux drum 11 in the upper part of the regenerator 3 , and is discharged to the outside of the regenerator 3 .

[0062] The reflux water with carbon dioxide dissolved therein is cooled in a reflux condenser 12, and then separated from a liquid component formed by condensing water vapor containing carbon dioxide in a reflux drum 11. This liquid component is led to an acid gas recovery step via a recovered acid gas line 13. Meanwhile, the reflux water from which the acid gas has been separated is sent to a regenerator 3.

[0063] According to the acidic gas removal apparatus 1 of the present embodiment, by using an acidic gas absorbent having excellent absorption and desorption properties for acidic gas, it becomes possible to perform highly efficient absorption and removal of acidic gas.

[0064] The reflux water from which the acid gas has been separated is sent to the regenerator 3 by a reflux water pump 14. According to the acid gas removal device 1 of this embodiment, by using an acid gas absorbent having excellent absorption and desorption properties for acid gas, it is possible to perform highly efficient absorption and removal of acid gas.

[0065] Hereinafter, the embodiments of the present invention will be described in more detail using examples.

[0066] [Synthesis Example] Synthesis of 1,4-bis(2-isopropylaminoethyl)piperazine (a1-1) (i) Synthesis of 1-chloro-2-(N-isopropyl)amino)ethane (M1) 36.4g (0.91mol) of sodium hydroxide was weighed out in a beaker, dissolved in water, and the solution was made up to 300ml. 0.6mol of 1-chloro-2-(N-isopropyl)amino)ethane·hydrochloride (2·HCl) synthesized by the above method was added to it, and after stirring well to dissolve, it was extracted three times with ether. The ether phase was dried over anhydrous sodium sulfate, and then concentrated until only a small amount of ether remained, to obtain 1-chloro-2-(N-isopropyl)amino)ethane (M1). (However, if all the ether is removed, compound 2 will gradually undergo a self-decomposition reaction.)

[0067] The synthesized compounds were measured using a 400 MHz NMR apparatus (JEOL model JMTC0-400 / 54 / SS, JELO model NM-SCM40SS / AL) to identify the compounds.

[0068] NMR spectrum of M1 1 H-NMR, (CDCl3, ppm) δ:1.08(d, 6H, J=6.4Hz), 2.84(m, 1H), 2.95(t, 2H, J=5.7Hz), 3.66(t,2H,J=5.7Hz), 13 C-NMR (CDCl3, ppm) δ:22.95, 45.12, 48.02, 48.45

[0069] (ii) Synthesis of 1,4-bis(2-isopropylaminoethyl)piperazine (a1-1) Next, 51.71g (0.60mol) of piperazine, 72.88g (0.72mol) of triethylamine and 200ml of acetonitrile were added to a four-neck flask equipped with a reflux condenser, a mechanical stirrer, a thermometer and a dropping funnel, and heated to 70°C. To this, a solution of 0.6mol of 1-chloro-2-(N-isopropyl)amino)ethane (M1) synthesized by the above method, to which 100ml of acetonitrile had been added and ether had been removed, was added. After dropping, the mixture was reacted at 70°C for 13 hours and then cooled to room temperature. The precipitate was removed by filtration from the reaction mixture, the filtrate was concentrated, the concentrate was redissolved in ether, and the precipitate was further filtered. The filtrate was dried over anhydrous sodium sulfate and then concentrated to obtain 37.49g of the reaction mixture (orange liquid). This reaction product was purified by column chromatography (activated alumina, developing solvent volume ratio of chloroform:hexane = 85:15) to obtain 15.62 g of the target compound (a1-1) as a yellow transparent liquid (19.8% based on raw material 2) and 9.75 g of 1-(2-isopropylaminoethyl)piperazine (M2) as a yellow transparent liquid (9.5%).

[0070] NMR spectrum of a1-1 1 H-NMR,(CDCl3,ppm)δ:1.06(d, 12H, J=5.9Hz), 2.49(t, 4H, J=6.4Hz), 2.4~2.7(m, 8H), 2.69(t,4H,J=6.4Hz), 2.76(m, 2H) 13 C-NMR(CDCl3, ppm)δ:23.03, 44.13, 48.90, 53.30, 58.04

[0071] NMR spectrum of M2 1 H-NMR, (CDCl3, ppm) δ:1.07(d, 6H, J=6.4Hz), 2.48(t, 2H, J=6.4Hz), 2.3~2.6(m, 4H), 2.70(t,2H, J=6.4Hz), 2.78(m,1H), 2.89(t, J=6.4Hz, 4H), 13 C-NMR (CDCl3, ppm) δ:23.07, 44.97, 46.20, 48.92, 54.69, 58.72

[0072] Synthesis of 1,4-bis[3-(N-isopropylamino)propyl]piperazine (a1-2) In a four-neck flask equipped with a reflux condenser with an argon inlet tube, a mechanical stirrer, a thermometer, and a dropping funnel, 100.33g (0.500mol) of 1,4-bis(3-aminopropyl)piperazine, 165.9g (1.20mol) of potassium carbonate, and 200ml of anhydrous acetonitrile were added under an argon atmosphere. The mixture was heated to about 70°C. A solution of 147.7g (1.18mol) of 2-bromopropane dissolved in 50ml of anhydrous acetonitrile was added dropwise from the dropping funnel. After the addition, the mixture was reacted at 70°C for 8 hours, and then a solution of 36.94g (0.30mol) of 2-bromopropane dissolved in 50ml of anhydrous acetonitrile was further added dropwise. The mixture was further reacted at 70°C for 12 hours and cooled to room temperature. The precipitate was removed by filtration from the reaction mixture, the filtrate was concentrated, the concentrate was redissolved in ether, and the precipitate was further filtered. The filtrate was dried over anhydrous sodium sulfate and then concentrated to obtain 120.7 g (yield 84.7%) of a pale yellow transparent liquid of 1,4-bis[3-(N-isopropylamino)propyl]piperazine (a1-2).

[0073] NMR spectrum of a1-2 1 H-NMR, (CDCl3, ppm) δ:1.05(d, 6H, J=6.4Hz), 1.67(m, 4H), 2.39(t, 2H, J=7.3Hz), 2.3~2.6(m, 8H), 2.63(t,2H, J=7.1Hz), 2.78(m,H) 13 C-NMR (CDCl3, ppm) δ:22.88, 27.27, 46.31, 48.63, 55.22, 57.08

[0074] Synthesis of 1,4-bis[3-(N-sec-butylamino)propyl]piperazine (a1-3) In a four-neck flask equipped with a reflux condenser with an argon inlet tube, a mechanical stirrer, a thermometer, and a dropping funnel, 100.33g (0.500mol) of 1,4-bis(3-aminopropyl)piperazine, 165.8g (1.20mol) of potassium carbonate, and 200ml of anhydrous acetonitrile were added under an argon atmosphere. The flask was heated to about 70°C. A solution of 164.54g (1.18mol) of 2-bromobutane dissolved in 50ml of anhydrous acetonitrile was added dropwise from the dropping funnel. After the addition, the mixture was reacted at 70°C for 24 hours, and then cooled to room temperature. The precipitate was removed from the reaction mixture by filtration, and the filtrate, which was washed with chloroform, was concentrated. The concentrate was redissolved in hexane, and the precipitate was removed by filtration. The filtrate was dried over anhydrous sodium sulfate, and then concentrated. The reaction product was separated by column chromatography (silica, hexane as a developing solvent by volume) and concentrated to obtain 95.2 g (yield %) of 1,4-bis[3-(N-sec-butylamino)propyl]piperazine (a1-3) as a pale yellow transparent liquid. The compound was identified by NMR.

[0075] NMR spectrum of a1-3 1 H-NMR, (CDCl3, ppm) δ:0.88(t, 6H, J=7.3Hz), 1.02(d, 6H, 6.9Hz), 1.30(m, 2H), 1.47(m, 2H), 1.67(m, 4H), 2.2~2.9(m, 14H), 2.39(t, 4H, J=7.3Hz), 13 C-NMR (CDCl3, ppm) δ:10.34, 19.83, 27.36, 29.53, 46.21, 53.33, 54.74, 57.21

[0076] Synthesis of 1-isopropyl-4-[2-(N-isopropylamino)ethyl]piperazine (a2-1) 38.76g (0.300mol) of 1-(2-aminoethyl)piperazine was added to a four-neck flask equipped with a reflux condenser with an argon inlet tube, a thermometer, a bottom funnel, and a mechanical stirrer, and 150ml of anhydrous acetonitrile was added to dissolve it. 99.59g (0.720mol) of potassium carbonate (K2CO3) was added to it. 49.29g (0.401mol) of 2-bromopropane dissolved in 40ml of anhydrous acetonitrile at room temperature was gradually added using a bottom funnel under an argon atmosphere. After the dropwise addition was completed, the mixture was heated in an oil bath and reacted at 65℃ for 4 hours, but it was found that the reaction solution had hardly progressed. After cooling to room temperature, the precipitate was filtered, washed with chloroform, and the washings were combined with the filtrate from before, and the filtrate was concentrated in an evaporator to remove the solvent. Diethyl ether was added to the residue to dissolve it, and the mixture was filtered. After drying the filtrate with anhydrous sodium sulfate, the solvent was concentrated with an evaporator to obtain 51.17 g of a pale yellow transparent liquid as the product. It was further purified by reduced pressure distillation to obtain the product (15.6 g) from the distillation components (distillation temperature 85-89 ° C (220 Pa)).

[0077] 1 H-NMR (CDCl3, ppm) δ:1.06(d, J=6.7Hz, 6H), 1.09(d,J=6.2Hz, 6H), 2.4~2.8(m, 14H) 13C-NMR (CDCl3, ppm) δ 18.62, 22.84, 44.07, 48.67, 48.82, 53.34, 54.34, 58.03

[0078] [Examples 1 to 26, Comparative Examples 1 to 18] The amines (a1-1 to a1-3), 2-(N-methylamino)ethanol (MEA), methyldiethanolamine (MDEA), 1-(2-hydroxyethyl)piperazine (HEPZ), 1-(2-aminoethyl)piperazine (AEPZ), and 1-(2-isopropylaminoethyl)piperazine (IPAEPZ) synthesized as shown in the synthesis examples were dissolved in water at the concentrations shown in Table 1 to prepare acidic gas absorbents.

[0079] [Evaluation of acid gas absorption rate] The acid gas absorbent was filled into a test tube and heated to 40°C, and a mixed gas containing 10% by volume of carbon dioxide (CO2) and 90% by volume of nitrogen (N2) was passed through the acid gas absorbent at a flow rate of 500 mL / min. The carbon dioxide (CO2) concentration in the gas at the outlet of the test tube was measured using an infrared gas concentration measuring device (Shimadzu Corporation, product name "CGT-700") to evaluate the absorption performance. The slope of the absorption curve obtained 10 minutes after the start of measurement was taken as the absorption rate. The results are shown in Tables 1-1 and 1-2.

[0080] [Table 1]

[0081] [Table 2-1]

[0082] [result] As is apparent from the above results, it is clear that the acidic gas absorbent according to the embodiment has a significantly improved carbon dioxide absorption rate as compared with the conventional acidic gas absorbent.

[0083] As described above, although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0084] Reference Signs List 1...Acid gas removal device, 2...Absorber, 3...Regenerator, 4...Gas supply port, 5...Acid gas absorbent supply port, 6...Gas outlet, 7...Heat exchanger, 8...Rich liquid pump, 9...Lean liquid pump, 10...Absorbent cooler, 11...Reflux drum, 12...Reflux cooler, 13...Acid gas carbon recovery line

Claims

1. (A) Formula (a1) or formula (a2): 【Chemical 1】 [In the formula, R １ are each independently hydrogen or an unsubstituted or substituted alkyl group having 3 or fewer carbon atoms, R ２ are each independently hydrogen or an unsubstituted or substituted alkyl group having 3 or fewer carbon atoms , and at least two of the Rs contained in one - CR ２ ３ are not hydrogen), and are represented by ２ a substituent, R R ３ is hydrogen or an unsubstituted or substituted alkyl group having 4 or fewer carbon atoms, p is each independently 0 or 1, m is a number from 1 to 3, n is each independently a number from 1 to 4]] a first amine compound represented by, (B) Formula (b): 【Chemical 2】 [In the formula, R ４ are each independently hydrogen or an unsubstituted or substituted alkyl group, and among the three Rs ４ at least one is not hydrogen, and a cyclic structure in which two Rs ４ are linked to each other may be taken. ] a second amine compound represented by, and, (C) a solvent is included, and the ratio B / A of the content of component (B) to the content of component (A) is 2.5 to 15 an acidic gas absorbent.

2. The acidic gas absorbent according to claim 1, wherein the ratio B / A is 3 to 12.

3. The acidic gas absorbent according to claim 1 or 2, wherein n is 2 or 3.

4. The acid gas absorbent according to claim 1 or 2, wherein m is 2.

5. The acid gas absorbent according to claim 1 or 2, wherein all of the p are 1.

6. Based on the total amount of the acid gas absorbent, the content of the component (A) is 3 to 20% by mass The acid gas absorbent according to claim 1 or 2.

7. An additive selected from the group consisting of (D) antioxidant, pH adjuster, defoaming agent, and corrosion inhibitor The acid gas absorbent according to claim 1 or 2, further comprising.

8. Contacting a gas containing an acid gas with the acid gas absorbent according to claim 1 or 2 An acid gas removal method comprising removing the acid gas from the gas containing the acid gas. .

9. By contacting a gas containing an acid gas with the acid gas absorbent according to claim 1 or 2 Absorbing the acid gas into the acid gas absorbent to remove the acid gas from the gas containing the acid gas An absorber, A regenerator for desorbing the acid gas from the acid gas absorbent that has absorbed the acid gas and regenerating the acid gas absorbent And Having An acid gas removal apparatus that reuses the acid gas absorbent regenerated in the regenerator in the absorber. Device.

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