KR20120029586A - Absorbents for separation of acidic gas from mixed gas and separation method using the same - Google Patents

Abstract

The present invention is a compound having two amines in the molecule, one of which is a primary amine and the other is a tertiary amine; And an acid gas absorbent comprising at least one compound selected from the group consisting of cyclic compounds having two or more amines in a molecule, a composition comprising the same, and an acid gas separation method. Excellent economy and excellent heat resistance.

Description

Absorbents for Separation of Acidic Gas from Mixed Gas and Separation Method using the Same}

The present invention relates to an absorbent for acidic gas separation and a method for separating acidic gas using the same, and more particularly, to acidic gas separation which has a fast reaction rate and high absorption capacity for acidic gas and does not require much energy for regeneration. It relates to an absorbent for solvents and a method for separating acid gases using the same.

Since the early 19th century, when the industrialization started, the use of fossil fuels such as coal, petroleum, and LNG used in the energy industry increased the concentration of acidic gases such as CO ₂ , CH ₄ , H ₂ S, and COS. Increasing acid gases have caused air pollution, and countries have stricter regulations on the emission and disposal of acid gases.

In particular, increasing atmospheric concentrations of carbon dioxide have accelerated global warming. The United Nations Conference on Environment and Development in Rio, Brazil, in June 1992 has raised international interest in global warming, and developed countries, including the United States and Japan, have decided to reduce global greenhouse gas emissions by 5.2% in 2010 compared to 1990. International agreements on how to reduce acid gases are being made. In particular, the separation of carbon dioxide, which accounts for most of the acidic gases that cause global warming, is emerging as a more important problem.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

The inventors of the present application are compounds having two amines in a molecule, one of which is a primary amine and the other is a tertiary amine; And it was confirmed that by using alone or mixed with a compound having two or more amines in the molecule, it is possible to reduce the energy required in the stripping process and to prevent corrosion without lowering the absorption rate and absorption rate for the acidic gas.

Accordingly, it is an object of the present invention to provide an acid gas separation absorbent, a composition comprising the same, and an acid gas separation method, which have excellent throughput and processing speed for acidic gas, as well as excellent heat resistance and economic efficiency.

In order to achieve the above object, the absorbent for acid gas separation according to the present invention includes a compound represented by the following Chemical Formula 1.

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,

X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms.

The compound of Formula 1 is a compound having two amines in the molecule, one of which is the primary amine and the other is characterized in that the tertiary amine. For example, the compound of Formula 1, in Formula 1, R ₁ and R ₂ may be an alkyl group having 1 to 3 carbon atoms having the same number of carbon atoms, X may be an alkylene group having 1 to 4 carbon atoms.

In one embodiment, the absorbent for acid gas separation may further include an amine compound of the formula (2).

(2)

In Chemical Formula 2,

R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6;

The absorbent for acid gas separation according to the present invention is very excellent in the absorption rate and the absorption amount for the acid gas as well as the stripping rate and stripping amount after absorption. In particular, since there is no hydroxyl group (-OH) in the molecule, there is an advantage that the generation of deterioration material is small. In addition, it is advantageous in terms of durability because it is superior in economic efficiency and excellent heat resistance compared to the existing absorbent.

The acid gas separation absorbent may include a compound of Formula 1, or may include both compounds of Formulas 1 and 2. In the case of including both the compound of Formula 1 and the amine compound of Formula 2, it may be used by mixing in various ratios depending on the amount of acid gas and the required processing speed. In one embodiment, the absorbent for acidic gas separation may include 10 to 200 parts by weight of the amine compound of Formula 2 based on 100 parts by weight of the compound of Formula 1. More specifically, the absorbent may include 50 to 150 parts by weight of the amine compound of Formula 2 based on 100 parts by weight of the compound of Formula 1. The content range is for simultaneously improving the absorption rate and absorption amount, and stripping rate and stripping amount of the acid gas. Specifically, when the content of the amine compound of Formula 2 is too low, the effect of improving the reaction rate is insignificant, and when it exceeds the above range, the efficiency of improving the reaction rate relative to the amount used may be lowered and the stripping rate may be lowered. .

The compound of Formula 1 is, for example, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, 1-dimethylamino-2-propylamine and N, N- It may be one kind or a mixture of two or more kinds selected from the group consisting of diethylethylenediamine. Further, the absorbent according to the present invention is N-methyl-2-amino-1-propanol, N-ethyl-2-amino-1-propanol, N-isopropyl-2-amino-1-poropanol, N-methyl -2-amino-1-butanol, N-methyl-2-amino-1-pentanol, N-isopropyl-2-amino-1-pentanol, 2-amino-1-propanol, 2-amino-1- Butanol, 2-amino-3-methylbutanol, 2-amino-1-pentanol, 2-amino-1-propanol, 2-amino-1-hexanol, 3-amino-1-butanol, 4-amino-1 It may include one or two compounds selected from the group consisting of -pentanol, 5-amino-1-hexanol, 3-amino-1-pentanol, 3-amino-1-hexanol and the like.

The amine compound of Formula 2 is, for example, piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5- Dimethylpiperazine, 2,4-dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1 1 type or 2 types selected from the group consisting of, 4-bis (1-aminomethyl) piperazine, 1,4-bis (2-aminoethyl) piperazine and 1,4-bis (3-aminopropyl) piperazine It may be a mixture of the above. In addition, the absorbent according to the present invention, piperazine, morpholine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,3-dimethylpiperazine, 2,4-dimethylpiperazine, 2-ethanolpiperazine , 2,5-diethanol piperazine, 2-aminoethyl piperazine, thiomorpholine, piperazine, including piperidine, morpholine, thiomorpholine, piperidine derivatives.

The acid gas which can be separated through the absorbent is not particularly limited, and may be, for example, any one or two or more selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO _2, and COS. In particular, the absorbent according to the present invention is capable of effective adsorption and separation of CO ₂ gas.

The invention also provides a compound of formula (1); And it provides an absorbent for acid gas separation comprising the amine compound of formula (2).

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,

X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms.

The compound of Formula 1 is a compound having two amines in the molecule, one of which is the primary amine and the other is characterized in that the tertiary amine. For example, the compound of Formula 1, in Formula 1, R ₁ and R ₂ may be an alkyl group having 1 to 3 carbon atoms having the same number of carbon atoms, X may be an alkylene group having 1 to 4 carbon atoms.

 (2)

In Chemical Formula 2,

R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6;

The absorbent for acid gas separation includes both the compound of Formula 1 and the amine compound of Formula 2, and may be used in various ratios depending on the amount of acid gas and the required processing speed. In one embodiment, the absorbent may include 10 to 200 parts by weight of the amine compound of Formula 2 based on 100 parts by weight of the compound of Formula 1. More specifically, the absorbent may include 50 to 150 parts by weight of the amine compound of Formula 2 based on 100 parts by weight of the compound of Formula 1. The content range is for simultaneously improving the absorption rate and absorption amount, and stripping rate and stripping amount of the acid gas. Specifically, when the content of the amine compound of Formula 2 is too low, the effect of improving the reaction rate is insignificant, and when it exceeds the above range, the efficiency of improving the reaction rate relative to the amount used may be lowered and the stripping rate may be lowered. .

The compound of Formula 1 is, for example, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, 1-dimethylamino-2-propylamine and N, N- It may be one kind or a mixture of two or more kinds selected from the group consisting of diethylethylenediamine. Further, the absorbent according to the present invention is N-methyl-2-amino-1-propanol, N-ethyl-2-amino-1-propanol, N-isopropyl-2-amino-1-poropanol, N-methyl -2-amino-1-butanol, N-methyl-2-amino-1-pentanol, N-isopropyl-2-amino-1-pentanol, 2-amino-1-propanol, 2-amino-1- Butanol, 2-amino-3-methylbutanol, 2-amino-1-pentanol, 2-amino-1-propanol, 2-amino-1-hexanol, 3-amino-1-butanol, 4-amino-1 It may include one or two compounds selected from the group consisting of -pentanol, 5-amino-1-hexanol, 3-amino-1-pentanol, 3-amino-1-hexanol and the like.

The amine compound of Formula 2 is, for example, piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5- Dimethylpiperazine, 2,4-dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1 1 type or 2 types selected from the group consisting of, 4-bis (1-aminomethyl) piperazine, 1,4-bis (2-aminoethyl) piperazine and 1,4-bis (3-aminopropyl) piperazine It may be a mixture of the above. In addition, the absorbent according to the present invention, piperazine, morpholine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,3-dimethylpiperazine, 2,4-dimethylpiperazine, 2-ethanolpiperazine , 2,5-diethanol piperazine, 2-aminoethyl piperazine, thiomorpholine, piperazine, including piperidine, morpholine, thiomorpholine, piperidine derivatives.

The acid gas which can be separated through the absorbent is not particularly limited, and may be, for example, any one or two or more selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO _2, and COS.

In addition, the present invention is a compound of Formula 1; And one or more solvents selected from the group consisting of water or alcohols having 1 to 6 carbon atoms.

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,

X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms.

The compound of Formula 1 is a compound having two amines in the molecule, one of which is the primary amine and the other is characterized in that the tertiary amine. For example, the compound of Formula 1, in Formula 1, R ₁ and R ₂ may be an alkyl group having 1 to 3 carbon atoms having the same number of carbon atoms, X may be an alkylene group having 1 to 4 carbon atoms.

In one embodiment, the absorbent composition may further comprise an amine compound of formula (2).

(2)

In Chemical Formula 2,

R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6;

The solvent of the absorbent composition may be one or two or more mixed solutions selected from the group consisting of water and alcohols having 1 to 6 carbon atoms. For example, the solvent may be water. When the solvent is water, the concentration of the absorbent composition may be in the range of 10 to 70% (w / v), more specifically 20 to 50% (w / v). When the concentration of the absorbent composition is less than the above range, the low concentration causes a decrease in performance when the absorbent is removed, thereby causing an increase in stripping energy. If the concentration of the absorbent exceeds the above range, the corrosion of the device by the absorbent is increased, and the resulting power ratio can be increased because the viscosity of the absorbent increases the capacity of the pump for supplying the absorbent in the process.

The acid gas which can be separated through the absorbent composition may be, for example, any one or two or more selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS.

The present invention also provides a method for separating acid gas using an absorbent.

In one embodiment, the separation method according to the present invention is to separate the acid gas by using an absorbent for acid gas separation comprising a compound of formula (1).

[Formula 1]

In Chemical Formula 1,

R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,

X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms.

The compound of Formula 1 is a compound having two amines in the molecule, one of which is the primary amine and the other is characterized in that the tertiary amine. For example, the compound of Formula 1, in Formula 1, R ₁ and R ₂ may be an alkyl group having 1 to 3 carbon atoms having the same number of carbon atoms, X may be an alkylene group having 1 to 4 carbon atoms.

In another embodiment, the absorbent used in the separation method may further include a compound of Formula 2 below.

 (2)

In Chemical Formula 2,

R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6;

The acid gas separation method may absorb the acid gas at 0 to 60 ° C., specifically 20 to 55 ° C., and remove the acid gas absorbed at 70 to 200 ° C., specifically, 90 to 130 ° C. In general, the process of separating acid gas consumes the most energy in the process of removing the absorbed gas. For example, in the separation and absorption process for carbon dioxide, a process of separating the absorbed carbon dioxide from the absorbent at a high temperature and regenerating (removing) the absorbent consumes about 50 to 80% of the energy of the entire process. Therefore, the lower the temperature required in the stripping process, the more economical it can be secured.

Acidic gas that can be separated through the separation method according to the invention is not particularly limited, for example, any one or two or more selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS. Can be. In particular, effective separation is possible for CO ₂ .

In the acidic gas separation method, the absorbent may be formulated in the form of an aqueous solution. The absorbent may be formulated in an aqueous solution in a concentration range of 10 to 70% (w / v), more specifically 20 to 50% (w / v). When the concentration of the absorbent aqueous solution is less than the above range, the reaction rate for the acidic gas containing carbon dioxide may be lowered. When the concentration exceeds the above range, the reaction rate improvement efficiency may be deteriorated according to the amount used.

As described above, the acid gas absorbent and the separation method using the same according to the present invention can improve the processing speed and throughput for acid gas at the same time, and are excellent in economic efficiency and excellent in heat resistance.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited thereto.

EXAMPLES 1-4

40% by weight of N, N-dimethyl-1,3-propanediamine of Formula 1 and 10% by weight of piperazine of Formula 2 were mixed to prepare an absorbent aqueous solution at a concentration of 50% (w / v) (Example 1). .

40% by weight of N, N-diethyl-1,3-propanediamine of Formula 1 and 10% by weight of piperazine of Formula 2 were mixed to prepare an absorbent aqueous solution at a concentration of 50% (w / v) (Example 2 ).

20% by weight of 1-dimethylamino-2-propylamine of Formula 1 and 10% by weight of piperazine of Formula 2 were mixed to prepare an aqueous solution of absorbent at a concentration of 30% (w / v) (Example 3).

In addition, 20% by weight of N, N-dimethyl-1,3-propanediamine of Formula 1 and 10% by weight of piperazine of Formula 2 were mixed to prepare an absorbent aqueous solution at a concentration of 30% (w / v) (Example 4).

[Comparative Examples 1-3]

Commercially available MEA (monoethanolamine) was mixed with water to prepare a concentration of 30% (w / w) (Comparative Example 1).

32% by weight of the primary amine 2-amino-2-methyl-1-propanol and 4% by weight of piperazine were mixed to prepare an aqueous absorbent solution at a concentration of 36% (w / v) (Comparative Example 2).

Then, 10% by weight of 2-amino-2-methyl-1-propanol as a primary amine, 25% by weight of diisopropanolamine as a secondary amine and 10% by weight of piperazine were mixed to absorb a 45% (w / v) concentration. An aqueous solution was prepared (Comparative Example 3).

Experimental Example 1

For the absorbents prepared in Examples 1 to 4 and Comparative Examples 1 to 3, the treatment capacity for carbon dioxide was compared. For each absorbent, the initial absorption rate, total absorption amount (gCO ₂ / L absorbent) and cumulative stripping amount (gCO ₂ / L absorbent) relative to MEA (monoethanolamine) were measured, respectively. The measurement results are shown in Table 1 below.

Absorbent Concentration
(% (w / v)) Initial Absorption Rate
Of MEA Total Absorption
(gCO ₂ / L absorbent) Cumulative removal
(gCO ₂ / L absorbent) Example 1 50 1.07 220.94 25.10 Example 2 50 1.09 198.57 20.21 Example 3 30 0.95 129.79 16.03 Example 4 30 1.02 147.89 16.19 Comparative Example 1 30 One 124.43 10.94 Comparative Example 2 36 0.60 122.71 15.55 Comparative Example 3 45 0.91 118.00 16.31

Referring to Table 1, the absorbents of Examples 1 to 4 can be seen that the initial absorption rate is similar or rather faster than the conventional absorbent MEA. Comparing the total absorbents, the absorbents of Examples 1 to 4 were generally superior to the absorbents of Comparative Examples 1 to 3, and in particular, the total absorbents of the absorbents of Example 1 were the largest. In addition, in the cumulative stripping amount, the absorbent of Example 1 was found to be about 2.5 times better than the MEA of Comparative Example 1.

Claims (25)

Absorbent for acid gas separation comprising the compound of formula 1:
[Chemical Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,
X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms. The method of claim 1,
An absorbent for acid gas separation, further comprising an amine compound represented by Chemical Formula 2:
[Formula 2]

In Chemical Formula 2,
R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6; The method of claim 1,
In Formula 1,
R ₁ and R ₂ are alkyl groups having 1 to 3 carbon atoms having the same number of carbon atoms,
X is an absorbent for acid gas separation, having 1 to 4 alkylene groups. The method of claim 2,
Acid absorbent for gas separation,
Based on 100 parts by weight of the compound of Formula 1,
An absorbent for acid gas separation, comprising 10 to 200 parts by weight of the amine compound of Formula 2. The method of claim 2,
Acid absorbent for gas separation,
Based on 100 parts by weight of the compound of Formula 1,
Absorbent for acidic gas separation comprising 50 to 150 parts by weight of the amine compound of Formula 2. The method of claim 1,
Compounds of the formula (1) include N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, 1-dimethylamino-2-propylamine and N, N-diethylethylene An absorbent for acid gas separation, which is one or a mixture of two or more selected from the group consisting of diamines. The method of claim 2,
The amine compound of formula (2) is piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5-dimethylpiperazine, 2 , 4-dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1,4-bis ( Acid gas which is one or a mixture of two or more selected from the group consisting of 1-aminomethyl) piperazine, 1,4-bis (2-aminoethyl) piperazine and 1,4-bis (3-aminopropyl) piperazine Absorbent for separation. The method according to claim 1 or 2,
The acidic gas is any one or two or more absorbents for acidic gas separation selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS. The method of claim 8,
Acid gas is absorbent for acid gas separation which is CO ₂ gas. A compound of formula 1; And
Absorbent for acid gas separation comprising the amine compound of Formula 2:
[Chemical Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,
X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms,
[Formula 2]

In Chemical Formula 2,
R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6; The method of claim 10,
Acid absorbent for gas separation,
Based on 100 parts by weight of the compound of Formula 1,
An absorbent for acid gas separation, comprising 10 to 200 parts by weight of the amine compound of Formula 2. The method of claim 10,
Compounds of the formula (1) include N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, 1-dimethylamino-2-propylamine and N, N-diethylethylene An absorbent for acid gas separation, which is one or a mixture of two or more selected from the group consisting of diamines. The method of claim 10,
The amine compound of formula (2) is piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5-dimethylpiperazine, 2 , 4-dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1,4-bis ( Acid gas which is one or a mixture of two or more selected from the group consisting of 1-aminomethyl) piperazine, 1,4-bis (2-aminoethyl) piperazine and 1,4-bis (3-aminopropyl) piperazine Absorbent for separation. The method of claim 10,
The acidic gas is any one or two or more absorbents for acidic gas separation selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS. A compound of formula 1; And
An absorbent composition for acidic gas separation comprising at least one solvent selected from the group consisting of water and alcohols having 1 to 6 carbon atoms:
[Chemical Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,
X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms. The method of claim 15,
The composition is an absorbent composition for acid gas separation further comprising an amine compound of formula:
[Formula 2]

In Chemical Formula 2,
R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6; The method according to claim 15 or 16,
The solvent is water absorbent composition for acid gas separation. The method of claim 17,
The concentration of the composition is 10 to 70% (w / v) absorbent composition for acidic gas separation. The method of claim 15,
The acid gas is any one or two or more selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS absorbent composition for acid gas separation. Acid gas separation method using an absorbent for acid gas separation comprising the compound of formula 1:
[Chemical Formula 1]

In Chemical Formula 1,
R ₁ and R ₂ are alkyl groups having 1 to 6 carbon atoms,
X is an alkylene group having 1 to 6 carbon atoms unsubstituted or substituted with an alkyl group having 1 to 6 carbon atoms. The method of claim 20,
The absorbent is an acidic gas separation method further comprises an amine compound of formula:
[Formula 2]

In Chemical Formula 2,
R ₃ to R ₈ are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or (CH ₂ ) _h -NH ₂ , where h is an integer of 1 to 6; 22. The method according to claim 20 or 21,
Acid gas separation method is an acid gas separation method that absorbs the acid gas at 0 ~ 60 ℃, remove the acid gas absorbed at 70 ~ 200 ℃. The method of claim 20,
The acid gas is one or more acid gas separation method selected from the group consisting of CO ₂ , H ₂ S, SO ₂ , NO ₂ and COS. 22. The method according to claim 20 or 21,
The acid gas separation method using the absorbent in the form of an aqueous solution. The method of claim 24,
The acid gas separation method using the absorbent in the form of an aqueous solution in the concentration range of 10 to 70% (w / v).