KR20200079686A - Ether-functional diamine-based carbon dioxide absorbents and method for preparing the same - Google Patents

Abstract

The present invention relates to a carbon dioxide absorbent comprising a diamine compound represented by chemical formula 1. According to the present invention, the carbon dioxide absorbent of the present invention does not generate solid salts even when dissolved in water at a high concentration to absorb carbon dioxide. Compared to a conventional water-based carbon dioxide absorbent, energy due to latent heat caused by water is reduced, and thus renewable energy can be reduced.

Description

Ether-functional diamine-based carbon dioxide absorbents and method for preparing the same}

The present invention relates to a carbon dioxide absorbent capable of selectively capturing and separating carbon dioxide contained in a combustion gas or industrial exhaust gas, and a method for manufacturing the same, more specifically, a high carbon dioxide absorption rate, a low stripping temperature, low renewable energy and high stability. It relates to a carbon dioxide absorbent having and a method for manufacturing the same.

The most effective way to remove carbon dioxide (CO ₂ ) from gas mixtures containing carbon dioxide, such as gas mixtures obtained from hydrogen, steel and cement production processes, combustion flue gas and natural gas from power plants using fossil fuels The physical absorption method using an organic solvent when the concentration is high, and the chemical absorption method using an amine aqueous solution when the concentration is low are mentioned. In the case of a physical absorption method suitable for a gas mixture having a high carbon dioxide concentration, its economic efficiency and efficacy have been proven in various commercialization processes such as hydrogen production and natural gas purification. On the other hand, in the case of removing carbon dioxide from combustion gas having a low carbon dioxide concentration, the chemical absorbent is much more effective than the physical absorbent, but the use of the chemical absorbent is still insufficient due to the problem of high absorbent renewable energy.

As the chemical absorbent, amine aqueous solutions such as monoethanolamine (MEA), diethanolamine (DEA), and piperazine have been studied the most, and these amine-based absorbents react with carbon dioxide to stabilize This is because mate compounds are easily formed, and these compounds can be decomposed again into carbon dioxide and amines by heat. However, the carbon dioxide capture process using these amine-based absorbents has some serious problems, in particular, due to the high thermal and chemical stability of carbamate generated from the reaction with carbon dioxide, the decomposition temperature is higher than 120°C and excessive renewable energy is consumed. In addition to the problem (in the case of MEA, renewable energy requires 4.0~4.2 GJ per ton of carbon dioxide), there is a problem of excessive volatilization loss of amine (4 Kg per ton in case of MEA) due to high regeneration temperature, and there is also a problem of supplementing the absorbent accordingly. .

In order to compensate for the disadvantages of the amine-based aqueous solution absorbent, attempts have been made to use an alkanolamine having a steric hindrance around the amine group of the alkanolamine as an absorbent, and a representative example is 2-amino-2-methyl, which is a primary amine. -1-propanol (AMP). AMP has the advantage of forming a bicarbonate compound ([AMPH][HCO ₃ ]) that is easier to regenerate than carbamate when reacting with carbon dioxide, so it has the advantage of 30% lower renewable energy than MEA, but the rate of carbon dioxide absorption is It has a disadvantage that is less than 50% of MEA.

As a way to increase the absorption rate of AMP, Mitsubishi Heavy Industries and Kansai Thermal Power Plant jointly developed and registered a new absorbent with a secondary ring amine piperazine added to AMP (Patent No. 3197173). However, the absorbent disclosed in the patent has a problem that precipitation occurs during the process of absorbing carbon dioxide, and piperazine and carbon dioxide react to form a thermally more stable carbamate in addition to the bicarbonate compound, and thus there is a problem of difficulty in regeneration.

In addition, a method of reducing renewable energy by using an alkali carbonate such as sodium carbonate or potassium carbonate as a carbon dioxide absorber instead of a primary alkanolamine absorber such as MEA is also known, but has a disadvantage of slow carbon dioxide absorption. As one of the ways to increase the carbon dioxide absorption rate, international publication WO 2004-089512 A1 reports that when piperazine or a derivative thereof is added to potassium carbonate, the carbon dioxide absorption rate is reported to increase significantly, but there is a problem of precipitation formation due to the use of carbonate. It remains a challenge to be solved.

When carbon dioxide is captured using an amine-based absorbent using water as a solvent, about 70% or more of the energy consumed is used for absorbent regeneration, of which 50% or more is due to the energy required to vaporize water, that is, the latent heat of water. It is known as energy. This means that the energy consumed in the collecting process may be significantly reduced when the absorbent solvent replaces an organic solvent having a higher boiling point than the absorbent regeneration temperature and having a small specific heat instead of water having high latent heat and specific heat. Based on this concept, WO2012-034921 A1 and WO2012-093853 A1 disclose patents that use a solution dissolved in AMP or t-butylaminoethanol (TBAE) alcohol with steric hindrance as a carbon dioxide absorbent. . However, the absorbents disclosed in the patent have a significant disadvantage that the loss of alcohol is large in the absorption and regeneration process because the absorption rate of carbon dioxide is significantly slower than that of MEA and exhibits efficacy only in low-boiling alcohols such as methanol. The absorbent exhibits the same performance as methanol even under a high-boiling alcohol ethylene glycol (EG) solvent, but has the disadvantage that the absorbent circulation is restricted because the viscosity of the solution rises excessively after carbon dioxide absorption.

As recently proposed in U.S. Patent No. 6,849,774, U.S. Patent No. 6,623,659, and U.S. Patent Publication No. 2008/0146849, an ionic liquid that maintains a liquid phase at a low temperature of 100° C. or less while having no volatility and high thermal stability Attempts have been made to use (ionic liquid) as a non-aqueous absorbent. However, in order to synthesize these ionic liquids, it is usually necessary to go through two or more complicated manufacturing processes, and the production cost is too high, and the absorption capacity of carbon dioxide at a low pressure and the absorption rate of carbon dioxide is too low, and the combustion is discharged to atmospheric pressure. There is a problem in that it is not appropriate to capture carbon dioxide from the off-gas.

The object of the present invention is to solve the above problems, it does not form a precipitate by reacting with carbon dioxide, it is dissolved in water well in the state combined with carbon dioxide as well as itself, so it can be used after dilution of water at a high concentration, so the concentration of water is relatively It is low, so it can reduce the total energy required compared to the conventional water-based absorbent, and can remove the absorbent combined with carbon dioxide at less than 100℃, reducing energy consumption due to latent heat of water. It is to provide a carbon dioxide absorbent containing a diamine-based compound containing an intramolecular ether group.

Another object of the present invention is to provide a method for effectively separating carbon dioxide by separating carbon dioxide by using a carbon dioxide absorbent containing a diamine-based compound containing an ether group in the molecule, and then removing it with low energy and reusing it multiple times.

According to one aspect of the invention,

A carbon dioxide absorbent comprising a diamine compound represented by Formula 1 below is provided.

[Formula 1]

In Formula 1,

n is a repetition number that is an integer selected from 0 to 10,

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted A C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a C6 to C30 aryl group,

R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, Or a substituted or unsubstituted C1 to C30 heteroaryl group.

Preferably, in Chemical Formula 1,

n is a repetition number that is an integer selected from 0 to 4

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), or a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

R ³ may be a hydrogen atom, a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group.

Even more preferably,

In Chemical Formula 1,

n is a repetition number which is any integer selected from 1 to 3,

R ¹ and R ² are the same or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t -Butyl group,

R ⁴ and R ⁵ One of them is a hydrogen atom, the other is a C1 to C10 alkyl group,

R ³ may be a hydrogen atom, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t-butyl group.

Most preferably, in Chemical Formula 1,

n is 1,

R ¹ and R ² are methyl groups,

R ³ may be a methyl group.

The carbon dioxide absorbent may be an aqueous solution containing the diamine compound represented by Chemical Formula 1 above.

The aqueous solution containing the diamine compound represented by Chemical Formula 1 may contain 20 to 80% by weight of the diamine compound represented by Chemical Formula 1.

According to the “other” aspect of the present invention,

A method for separating carbon dioxide using a carbon dioxide absorbent containing a diamine compound represented by the following Chemical Formula 1 is provided.

[Formula 1]

In Formula 1,

n is a repetition number that is an integer selected from 0 to 10,

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted A C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a C6 to C30 aryl group,

R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, Or a substituted or unsubstituted C1 to C30 heteroaryl group.

Preferably, in Chemical Formula 1,

n is a repetition number that is an integer selected from 0 to 4

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), or a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

R ³ may be a hydrogen atom, a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group.

More preferably, in the above Chemical Formula 1,

n is a repetition number which is any integer selected from 1 to 3,

R ¹ and R ² are the same or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t -Butyl group,

R ⁴ and R ⁵ One of them is a hydrogen atom, the other is a C1 to C10 alkyl group,

R ³ may be a hydrogen atom, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t-butyl group.

Most preferably, in Chemical Formula 1,

n is 1,

R ¹ and R ² are methyl groups,

R ³ may be a methyl group.

The separation method of carbon dioxide,

(a) an absorption step of absorbing carbon dioxide from a gas mixture containing carbon dioxide by using an aqueous solution containing a diamine compound represented by Formula 1 as a carbon dioxide absorbent; And

(b) a stripping step of stripping the carbon dioxide absorbed by the carbon dioxide absorbent; may include.

In step (a), the temperature upon absorption of carbon dioxide may be 20 to 60°C.

In step (a), the pressure during carbon dioxide absorption may be 1 to 20 atmospheres.

In step (a), the ratio (L/G) of the carbon dioxide absorbent to the gas mixture containing carbon dioxide may be 2 to 7 L/Nm ³ .

When removing carbon dioxide in step (b), the temperature may be 80 to 100°C.

In step (b), carbon dioxide stripping may be performed at 1 atmosphere.

After step (b), the reuse step of performing steps (a) and (b) can be further performed using carbon dioxide removed and regenerated carbon dioxide absorbent.

The reuse step can be repeated multiple times.

The carbon dioxide absorbent of the present invention does not form a precipitate by reacting with carbon dioxide, and is dissolved in water well in itself and combined with carbon dioxide, so it can be used by diluting water at a high concentration. Can reduce the overall energy being. In addition, since the absorbent combined with carbon dioxide can be removed at 100° C. or less, energy consumption due to latent heat of water can be reduced, and consequently, the regenerative energy of the absorbent is low, so that it is excellent in regeneration and economical efficiency is high.

In addition, the carbon dioxide separation method of the present invention uses carbon dioxide absorbents containing a diamine-based compound containing an ether group in the molecule to separate carbon dioxide and then remove it with low energy and reuse it multiple times, so there is little change in performance. It can be separated very efficiently.

1 is a schematic diagram of a carbon dioxide absorption test apparatus.
2 is a result of NMR analysis of the absorbent after carbon dioxide absorption in Experimental Example 1.
3 is a result of a repeated test for carbon dioxide absorption, stripping, and reabsorption of Experimental Example 5.
4 is a test apparatus for measuring the renewable energy of the carbon dioxide absorbent of Experimental Example 6.

The present invention can be applied to a variety of transformations and may have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In the description of the present invention, when it is determined that a detailed description of related known technologies may obscure the subject matter of the present invention, the detailed description will be omitted.

The "substituted" is at least one hydrogen atom deuterium, C1 to C30 alkyl group, C3 to C30 cycloalkyl group, C2 to C30 heterocycloalkyl group, C1 to C30 halogenated alkyl group, C6 to C30 aryl group, C1 to C30 heteroaryl group, C1 to C30 alkoxy group, C3 to C30 cycloalkoxy group, C1 to C30 heterocycloalkoxy group, C2 to C30 alkenyl group, C2 to C30 alkynyl group, C6 to C30 aryloxy group, C1 to C30 heteroaryloxy group, silyloxy Period (-OSiH ₃ ), -OSiR ¹ H ₂ (R ¹ is a C1 to C30 alkyl group or C6 to C30 aryl group), -OSiR ¹ R ² H (R ¹ and R ² are each independently a C1 to C30 alkyl group or C6 To C30 aryl group), -OSiR ¹ R ² R ³ , (R ¹ , R ² , and R ³ are each independently a C1 to C30 alkyl group or a C6 to C30 aryl group), a C1 to C30 acyl group, a C2 to C30 acyl Oxy group, C2 to C30 heteroaryloxy group, C1 to C30 sulfonyl group, C1 to C30 alkylthiol group, C3 to C30 cycloalkylthiol group, C1 to C30 heterocycloalkylthiol group, C6 to C30 arylthiol group, C1 to C30 heteroaryl thiol group, C1 to C30 phosphate group, silyl group (SiR ¹ R ² R ³ ₎ (R ¹ , R ² , and R ³ are each independently a hydrogen atom, a C1 to C30 alkyl group or a C6 to C30 aryl group ), amine group (-NRR'), wherein R and R'are each independently a substituent selected from the group consisting of a hydrogen atom, a C1 to C30 alkyl group, and a C6 to C30 aryl group, a carboxyl group, a halogen group, It means substituted with a substituent selected from the group consisting of a cyano group, a nitro group, an azo group, and a hydroxyl group.

In addition, two adjacent substituents may be fused to form a saturated or unsaturated ring.

In addition, the carbon number range of the alkyl group or the aryl group in the "substituted or unsubstituted C1 to C30 alkyl group" or "substituted or unsubstituted C6 to C30 aryl group" is unsubstituted without considering the part where the substituent is substituted. It means the total number of carbon atoms constituting the alkyl portion or the aryl portion as viewed. For example, the phenyl group substituted with a butyl group in the para position means that it corresponds to an aryl group having 6 carbon atoms substituted with a butyl group having 4 carbon atoms.

“Hetero” in the present specification means that, unless otherwise defined, one functional group contains 1 to 4 hetero atoms selected from the group consisting of N, O, S, and P, and the rest is carbon.

“Hydrogen” in this specification means mono-, bi-, or tri-hydrogen, unless otherwise defined.

"Alkyl (alkyl) group" as used herein means an aliphatic hydrocarbon group, unless otherwise defined.

The alkyl group may be a "saturated alkyl group" that does not contain any double or triple bonds.

The alkyl group may be a “unsaturated alkyl group” containing at least one double bond or triple bond.

The alkyl group, whether saturated or unsaturated, can be pulverized, straight or cyclic.

The alkyl group may be a C1 to C30 alkyl group. More specifically, it may be a C1 to C20 alkyl group, a C1 to C10 alkyl group, or a C1 to C6 alkyl group.

For example, C1 to C4 alkyl groups are 1 to 4 carbon atoms in the alkyl chain, i.e., the alkyl chain is methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl. It is selected from the group consisting of.

For a specific example, the alkyl group is a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, ethenyl group, propenyl group, butenyl group, cyclopropyl group, cyclo It means a butyl group, a cyclopentyl group, a cyclohexyl group, etc.

An “amine group” includes an amino group, an arylamine group, an alkylamine group, an arylalkylamine group, or an alkylarylamine group, and may be represented by -NRR', wherein R and R'are each independently a hydrogen atom , C1 to C30 alkyl group, and C6 to C30 aryl group.

“Cycloalkyl group” includes a monocyclic or fused ring polycyclic (ie, ring that divides adjacent pairs of carbon atoms) functional groups.

“Heterocycloalkyl group” means that the cycloalkyl group contains 1 to 4 heteroatoms selected from the group consisting of N, O, S, and P, and the rest is carbon. When the heterocycloalkyl group is a fused ring, at least one ring of the fused ring may include 1 to 4 heteroatoms.

“Aromatic group” means a functional group in which all elements of a ring-shaped functional group have p-orbitals, and these p-orbitals form a conjugate. A specific example is an aryl group and a heteroaryl group.

An “aryl group” includes a monocyclic or fused ring polycyclic (ie, ring that divides adjacent pairs of carbon atoms) functional groups.

"Heteroaryl (heteroaryl) group" means that the aryl group contains 1 to 4 heteroatoms selected from the group consisting of N, O, S and P, and the rest is carbon. When the heteroaryl group is a fused ring, at least one ring of the fused ring may include 1 to 4 heteroatoms.

The number of atoms in the ring in the aryl group and heteroaryl group is the sum of the number of carbon atoms and non-carbon atoms.

Hereinafter, the carbon dioxide absorbent of the present invention will be described.

The carbon dioxide absorbent of the present invention includes a diamine compound represented by Formula 1 below.

[Formula 1]

In Formula 1,

n is a repetition number that is an integer selected from 0 to 10,

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted A C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a C6 to C30 aryl group,

R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, Or a substituted or unsubstituted C1 to C30 heteroaryl group.

Preferably,

In Chemical Formula 1,

n is a repetition number that is an integer selected from 0 to 4

R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), or a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group,

R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

R ³ may be a hydrogen atom, a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group.

More preferably,

In Chemical Formula 1,

n is a repetition number which is any integer selected from 1 to 3,

R ¹ and R ² are the same or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t -Butyl group,

R ⁴ and R ⁵ One of them is a hydrogen atom, the other is a C1 to C10 alkyl group,

R ³ may be a hydrogen atom, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t-butyl group.

Most preferably, in Chemical Formula 1,

n is 1,

R ¹ and R ² are methyl groups,

R ³ may be a methyl group.

The carbon dioxide absorbent may be an aqueous solution containing a diamine compound represented by Chemical Formula 1.

The aqueous solution containing the diamine compound represented by Chemical Formula 1 preferably contains 20 to 80% by weight of the diamine compound represented by Chemical Formula 1, and more preferably 30 to 70% by weight. When the content of the diamine compound is less than 20% by weight, the absorption rate and absorption capacity of carbon dioxide decreases, and when it exceeds 80% by weight, the increase in absorption capacity and absorption rate is small, whereas the viscosity of the absorption liquid increases, so that the absorption of the absorbent becomes difficult and energy consumption increases. have.

Hereinafter, the method of "separation" of the carbon dioxide of the present invention will be described.

The method of “separation of carbon dioxide” of the present invention is characterized by using a “carbon dioxide” absorbent containing “diamine” compound represented by the formula “1” above.

Since the “diamine” compound represented by “Formula 1” above is the same as the above-mentioned bar, “specific” content will be referred to the “section”.

Specifically, the method of separating the carbon dioxide is as follows.

First, represented by the formula (1) Diamine Carbon dioxide is absorbed from a gas mixture containing carbon dioxide by using an aqueous solution containing the compound as a carbon dioxide absorber (step 　a).

At this time, it is preferred that the temperature at the time of carbon dioxide absorption is 20 to 60°C, and more preferably 20 to 30°C. When the absorption temperature exceeds 60°C, the amount of carbon dioxide absorption decreases because carbon dioxide stripping proceeds at the same time, and when the absorption temperature is less than 20°C, an additional refrigeration facility is required to lower the temperature, which is unfavorable in economic efficiency.

When absorbing carbon dioxide, the pressure is preferably 1 to 20 atm, preferably 1 to 10 atm, and even more preferably at atmospheric pressure, i.e., at about 1 atm. In general, the “pressure” of the exhaust gas is “normal pressure,” so it is most economical that absorption takes place at “normal pressure”.

The ratio (L/G) of the carbon dioxide absorbent to the gas mixture containing carbon dioxide is preferably 2 to 7 L/Nm ³ , and more preferably 3 to 6 L/Nm ^3. When is less than 2, the viscosity of the absorbent may increase due to long-term contact with the liquid, and when it exceeds 7, the separation performance may decrease due to a small amount of CO ₂ absorbed.

Next, the carbon dioxide absorbed by the carbon dioxide absorbent Remove (Step b).

At this time, the temperature when removing the carbon dioxide is preferably 80 to 100 ℃. When the temperature at the time of removal is less than 80° C., the amount of carbon dioxide removal is greatly reduced, and when it exceeds 100° C., energy by latent heat of water is further consumed, so that the advantage of the present invention may be reduced.

It is also desirable that the removal at the “main” stage is carried out at 1 atmosphere. In the case of a high pressure of 1 atm or higher, the partial pressure of carbon dioxide must be high to maintain the pressure, so a high temperature is required, which may deteriorate economic efficiency.

After step (b), the reuse step of performing steps (a) and (b) can be further performed using carbon dioxide removed and regenerated carbon dioxide absorbent.

The reuse step can be repeated multiple times.

In particular, in the carbon dioxide separation method according to the present invention, the concentration of the aqueous solution containing the compound represented by Formula 1 in step (a), a diamine compound, the temperature and pressure when absorbing carbon dioxide, the carbon dioxide for the gas mixture containing carbon dioxide When the carbon dioxide is removed from the ratio (L/G) of the absorbent, (b), the temperature, pressure, and reuse are different. As a result of performing the carbon dioxide separation experiment, the carbon dioxide separation efficiency when all of the following conditions are satisfied, unlike other conditions: It showed that the renewable energy efficiency was the highest, and the conditions are as follows.

The compound represented by Formula 1 in step (a) is n in Formula 1 is 1, R ¹ and R ² are methyl groups, R ³ is a methyl group compound, and the concentration of the aqueous solution containing the diamine compound is diamine compound: water = 60:40, the temperature when absorbing carbon dioxide is 20 to 30 ℃, the pressure is 1 atm, the ratio of the carbon dioxide absorber to the gas mixture containing carbon dioxide (L/G) is 3 to 6 L/Nm ³ , (b When removing carbon dioxide from ), the temperature is 90 to 100°C, the pressure is 1 atm, and the reuse is 1 to 5 times.

Hereinafter, preferred embodiments are provided to help understanding of the present invention. However, these examples are intended to illustrate the present invention in more detail, and the scope of the present invention is not limited thereto, and various changes and modifications can be made within the scope and technical scope of the present invention. It will be obvious to those who have knowledge.

[Example]

Carbon dioxide absorption test apparatus and method

The carbon dioxide absorption performance experiment was performed using the apparatus of FIG. 1. The apparatus of FIG. 1 is a 60 ml high pressure vial reactor (R1) with a thermometer (T2) attached, a pressure transducer (P1) for high pressure (0 to 70 atm), and 75 ml with a thermometer (T1) attached It consists of a cylinder (2) for storing carbon dioxide (S2) and a stirrer (1), and is installed in a thermostat to measure the carbon dioxide absorption capacity at a constant temperature. In addition, a carbon dioxide supply container (S1) and a pressure gauge (P2) were installed outside the thermostat.

A certain amount of absorbent and a magnetic rod were put together in the absorption reactor (R1), and the total weight of the reactor was measured, and then transferred to a constant temperature oven to maintain the temperature inside the reactor at 40°C. Next, after closing the valve (V4) connected to the absorption reactor (R1), put 50 atm of carbon dioxide into the storage cylinder (S2), record the equilibrium pressure and temperature, then stop the stirring of the absorption reactor (R1) and stop the valve ( V4) and after maintaining the pressure of the absorption reactor (R1) constant using a pressure regulator, record the pressure and temperature in the equilibrium state of the storage cylinder (S2), start stirring, and store the cylinder in 1 minute increments. The pressure and temperature of (S2) were recorded and the change in weight of the absorption reactor (R1) was measured after 30 minutes.

carbon dioxide Removal Experimental method

In the case of the carbon dioxide stripping experiment, after closing the valve (V4) and raising the temperature of the absorption reactor (R1) to 100°C using a heating mantle, the valve (V4), valve (V5) and valve (V6) Carbon dioxide was removed for 30 minutes while opening and supplying nitrogen to the absorption reactor (R1) at 20 ml/min. Thereafter, the temperature was lowered to room temperature and the weight change before and after stripping was measured.

Example One

(1) CO2 absorption

In Formula 1, R ¹ and R ² are methyl groups, and n is a carbon dioxide absorption experiment using a diamine compound having a structure of 1. 30 g of the non-aqueous absorbent having a weight ratio of 60/40 of the diamine compound/water was charged into the absorption reactor (R1) of FIG. 1 described above, and the carbon dioxide absorption experiment was performed after fixing the temperature of the reactor at 40°C. After stopping the stirring of the absorption reactor (R1) and using the valve (V4) and pressure regulator to record the pressure in the equilibrium state of the storage cylinder (S2) while maintaining the pressure of the absorption reactor (R1) at 1 atmosphere, Start stirring again and record the pressure change of the storage cylinder (S2) for 30 minutes in 1 minute increments and calculate the carbon dioxide absorption from the result. In addition, for the accuracy of the experiment, the amount of carbon dioxide absorbed was determined by measuring the weight of the reactor before and after absorption.

(2) Carbon dioxide removal and reabsorption

In the case of the removal and carbon dioxide reabsorption experiment, close the valve (V4), raise the temperature of the absorption reactor (R1) to 100 °C, open the valve (V4), valve (V5) and valve (V6) and open at 20 mL/min. As a result of removing carbon dioxide for 30 minutes while supplying nitrogen to the absorption reactor (R1), it was confirmed that the carbon dioxide absorbed in the whole absorption process was removed. Thereafter, an experiment of reabsorbing carbon dioxide at 40°C was performed. In addition, in order to ensure the accuracy of the measurement, the weight change of the absorption reactor (R1) is measured before and after the absorption and stripping experiments, and as a result, carbon dioxide absorption capacity (mol CO ₂ /mol absorbent), carbon dioxide absorption capacity when reabsorbing carbon dioxide after stripping (mol CO ₂ /mol absorbent) and regeneration rate (reabsorption/initial absorption after removal) were measured.

Example 2

In Formula 1, R ¹ and R ² are methyl groups, n is 1 instead of a diamine compound having a structure, in Formula 1, R ¹ and R ² are propyl groups, and n is a diamine compound having a structure except 1 is used. Then, carbon dioxide absorption and stripping experiments were performed in the same manner as in Example 1.

Example 3

In Formula 1, R ¹ and R ² are methyl groups, n is 1 instead of a diamine compound having a structure, in Formula 1, R ¹ and R ² are butyl groups, and n is a diamine compound having a structure except 1 is used. Then, carbon dioxide absorption and stripping experiments were performed in the same manner as in Example 1.

Example 4

In Formula 1, R ¹ and R ² are methyl groups, n is a diamine compound having a structure of 1, R ¹ and R ² in Formula 1 are hexylamine groups, and n is a diamine compound having a structure of 1 is used. Except for the carbon dioxide absorption and stripping experiment was carried out in the same manner as in Example 1.

Example 5

In Formula 1, R ¹ and R ² are methyl groups, n is a diamine compound having a structure of 1, R ¹ and R ² in Formula 1 are propyl groups, and n is a diamine compound having a structure of 2 is excluded. Then, carbon dioxide absorption and stripping experiments were performed in the same manner as in Example 1.

Example 6

In Formula 1, R ¹ and R ² are methyl groups, n is 1 instead of a diamine compound having a structure, in Formula 1, R ¹ and R ² are butyl groups, and n is a diamine compound having a structure of 2 is excluded. Then, carbon dioxide absorption and stripping experiments were performed in the same manner as in Example 1.

Example 7

In Formula 1, R ¹ and R ² are methyl groups, n is 1 instead of a diamine compound having a structure, in Formula 1, R ¹ and R ² are propyl groups, and n is a diamine compound having a structure of 3 is excluded. Then, carbon dioxide absorption and stripping experiments were performed in the same manner as in Example 1.

Example 8

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the temperature of the reactor was set to 20°C instead of 40°C.

Example 9

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the reactor temperature was set to 30°C instead of 40°C.

Example 10

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the temperature of the reactor was 50°C instead of 40°C.

Example 11

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the reactor temperature was set to 60°C instead of 40°C.

Example 12

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the absorption reactor pressure was 2 atm instead of 1 atm.

Example 13

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the absorption reactor pressure was 5 atm instead of 1 atm.

Example 14

When absorbing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the absorption reactor pressure was 10 atm instead of 1 atm.

Example 15

When removing carbon dioxide, carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that the temperature was set to 80°C instead of 100°C.

Example 16

Carbon dioxide absorption, stripping, and reabsorption experiments were carried out in the same manner as in Example 1, except that the temperature was 90°C instead of 100°C when removing carbon dioxide.

Example 17

The carbon dioxide absorption, stripping, and reabsorption processes of Example 1 were repeatedly performed 5 times.

Comparative example One

In Formula 1, R ¹ and R ² are methyl groups, n is a diamine compound having a structure of 1, instead of a non-aqueous absorbent having a weight ratio of 60/40, an aqueous solution containing 30% by weight of monoethanolamine (MEA) Carbon dioxide absorption, stripping, and reabsorption experiments were performed in the same manner as in Example 1, except that it was used as an absorbent.

Comparative example 2

The carbon dioxide absorption, stripping, and reabsorption processes of Comparative Example 1 were repeatedly performed 5 times.

The carbon dioxide absorption, stripping, and reabsorption conditions of Examples 1 to 17 and Comparative Examples 1 and 2 are summarized below.

division Absorbent component (diamine compound of formula 1) Absorption temperature
(℃) Absorption pressure
(atmospheric pressure) Stripping temperature
(℃) Absorption/removal/reabsorption cycle R ¹ and R ² n Example 1 methyl One 40 One 100 One Example 2 profile One 40 One 100 One Example 3 Butyl One 40 One 100 One Example 4 Hexylamine One 40 One 100 One Example 5 profile 2 40 One 100 One Example 6 Butyl 2 40 One 100 One Example 7 profile 3 40 One 100 One Example 8 methyl One 20 One 100 One Example 9 methyl One 30 One 100 One Example 10 methyl One 50 One 100 One Example 11 methyl One 60 One 100 One Example 12 methyl One 40 2 100 One Example 13 methyl One 40 5 100 One Example 14 methyl One 40 10 100 One Example 15 methyl One 40 One 80 One Example 16 methyl One 40 One 90 One Example 17 methyl One 40 One 100 5 Comparative Example 1 Monoethanolamine 40 One 100 One Comparative Example 2 Monoethanolamine 40 One 100 5

[Experimental Example]

Experimental Example 1: Absorbent after carbon dioxide absorption NMR analysis

The results of 13C-NMR analysis after carbon dioxide absorption of the carbon dioxide absorbent of Example 1 (ether diamine) and the carbon dioxide absorbent of Comparative Example 1 (MEA) are shown in FIG. 2. Where: a) 0.5 mol CO ₂ /mol MEA, b) 0.5 mol CO ₂ /mol etherdiamine, c) 0.82 mol CO ₂ /mol etherdiamine. The amine-based compound of Example 1 has a certain degree of steric hindrance around the amino group compared to primary amines such as monoethanolamine (MEA), and thus has high thermal stability like other primary amines when reacting with carbon dioxide in an aqueous solution. It forms a carbamate compound, but when water is present, it can be converted into bicarbonate, which is rapidly regenerated, as shown in Scheme 1 below.

In addition, the amine-based compound of the present invention does not precipitate as a solid by reaction with CO ₂ even when present in a relatively high concentration in water because a hydrophilic ether group exists in the molecule.

[Scheme 1]

Therefore, in the case of using the carbon dioxide absorbent of the present invention, since the stripping occurs even at 100° C. or less, energy consumption due to latent heat of water can be significantly lowered, and thus the total renewable energy can be significantly reduced compared to the existing water-based absorbent. The absorption rate of carbon dioxide also has a much higher advantage than the conventional non-aqueous absorbent ionic liquid and amine-alcohol mixed solution.

Experimental Example 2: Diamine CO2 according to absorbent change Absorption capacity And refresh rate measurement

Example 1 Carbon dioxide absorption, stripping, and uptake experiments of carbon dioxide absorption capacity (mol CO ₂ / mol absorbent), and then stripping the carbon dioxide uptake carbon dioxide absorption capacity (mol CO ₂ / mol absorbing agent) according to to 7 according to the conducted respectively and refresh rate (Reabsorption ability / initial absorption ability after removal) is shown in Table 2 below.

division Absorbent component (diamine compound of formula 1) CO ₂ absorption capacity
(mol CO ₂ /mol absorbent) CO ₂ reabsorption capacity
(mol CO ₂ /mol absorbent) Refresh rate (%) R ¹ and R ² n Example 1 methyl One 0.94 0.93 99 Example 2 profile One 0.92 0.90 98 Example 3 Butyl One 0.93 0.90 97 Example 4 Hexylamine One 0.96 0.95 99 Example 5 profile 2 0.95 0.91 96 Example 6 Butyl 2 0.94 0.90 96 Example 7 profile 3 0.95 0.92 97

Experimental Example 3: Carbon dioxide according to absorption temperature change Absorption capacity And refresh rate measurement

The carbon dioxide absorption, stripping, and reabsorption experiments of Example 1, and Examples 8 to 11, in which the absorption temperature of the same composition as in Example 1 was changed, and the absorption temperature was changed while the carbon dioxide pressure was fixed at 1 atmosphere, and , The results are shown in Table 3 below.

division Absorption temperature (℃) CO ₂ absorption capacity
(mol CO ₂ /mol absorbent) CO ₂ reabsorption capacity
(mol CO ₂ /mol absorbent) Refresh rate (%) Example 1 40 0.94 0.93 99 Example 8 20 1.42 1.38 97 Example 9 30 1.24 1.20 97 Example 10 50 0.94 0.92 98 Example 11 60 0.90 0.84 93

Experimental Example 4: absorption pressure and Stripping temperature Carbon dioxide following changes Absorption capacity And refresh rate measurement

The carbon dioxide absorption, stripping, and reabsorption experiments of Example 1 and Examples 12 to 16 were performed using the absorbent having the same composition as in Example 1 and changing the absorption pressure and stripping temperature while the absorption temperature was fixed at 40°C. And the results are shown in Table 4 below.

division Absorption pressure (atmospheric pressure) Stripping temperature
(℃) CO ₂ absorption capacity
(mol CO ₂ /mol absorbent) CO ₂ reabsorption capacity
(mol CO ₂ /mol absorbent) Refresh rate (%) Example 1 One 100 0.94 0.93 99 Example 12 2 100 1.21 1.18 98 Example 13 5 100 1.32 1.27 96 Example 14 10 100 1.43 1.33 93 Example 15 One 80 0.94 0.73 77 Example 16 One 90 0.94 0.87 92

Experimental Example 5: carbon dioxide absorption, Removal , Repeat test of reabsorption

According to Example 17 and Comparative Example 2, the carbon dioxide absorption, stripping, and reabsorption processes were continuously repeated five times, and the results are shown in FIG. 3.

According to this, it was confirmed that despite the repeated experiments, there was almost no change in the performance of the absorbent, and although no change in the performance of the absorbent was observed, the absorption amount was lower than in Example 17 in Comparative Example 2.

In addition, although the carbon dioxide absorption capacity was 1.05 moles per mole of the absorbent, it was confirmed that when the carbon dioxide was reabsorbed after 100°C removal, the carbon dioxide absorption capacity was 0.34 moles and the regeneration rate was only 34.4%. When the amount of the absorbent is 30% by weight or more, the amine-CO ₂ bond precipitates as a solid.

Experimental Example 6: Renewable energy measurement

The experiment for measuring the renewable energy of the absorbent was performed using the apparatus of FIG. 4. The device includes an absorption tower (C02) and a heat exchanger (HX02) for reboiling carbon dioxide, a pump (P03) and a constant temperature circulation device (CW02) for condensing water vapor at the top, and a stripping tower equipped with a storage tank (T02). (C03), and an absorbent heat exchanger (HX01) that exchanges heat between the absorbed absorbent and the regenerated absorbent. For the circulation of the absorbent, one pump (P01, P02) was installed at the bottom of the absorber (C02) and the stripping column (C03), respectively, and the regenerated absorbent passing through the absorbent heat exchanger (HX01) was added to the absorber (C02). A constant temperature circulation device (CW01) is further installed to lower the temperature to room temperature before being supplied. In addition, a wet tower (C01) was installed before the absorption tower (C02) to make the gas to be treated saturated with water vapor.

The gas to be treated which has become saturated in water vapor through the wet tower (C01) is supplied from the bottom of the absorption tower (C02), and the absorbent falls to the bottom from the top of the absorption tower (C02). The absorbent that selectively absorbs carbon dioxide from the gas to be treated is collected under the absorption tower C02, and is supplied to the stripping column C03 through the absorber heat exchanger HX01 through the pump P01. The absorbent absorbed by the carbon dioxide falls to the bottom of the stripping column (C03) and is heated through a reboiler composed of a heat exchanger (HX02) and a pump (P03) to separate the carbon dioxide and the absorbent. The regenerated absorbent is again supplied to the top of the absorption tower (C01) through the absorber heat exchanger (HX01) through the pump (P02). The temperature of the absorbent regenerated is reduced through the heat exchanger between the absorbent regenerated in the absorbent heat exchanger (HX01) and the absorbent absorbing the discharged carbon dioxide, and the heated absorbent absorbed reduces the thermal energy supplied for the removal of carbon dioxide from the stripping column.

The component ratio including carbon dioxide of the gas to be treated was specified, and an experiment for measuring renewable energy was performed while maintaining the flow rate at 1.2 Nm ³ /hr. In the state where the thermal energy supplied through the heat exchanger (HX02) to the stripping column (C03) is kept constant, the pressure of the stripping column (C03) and the circulating flow rate of the absorbent supplied to the pumps (P01, P02) are changed to achieve the lowest regeneration. Energy was measured. The calculation of renewable energy was calculated as the ratio of the difference between the amount of carbon dioxide in the gas to be treated and the amount of carbon dioxide in the exhaust gas discharged to the top of the absorption tower (C02) and the thermal energy supplied to the stripping tower (C03).

As a result of the experiment, the optimum operating conditions of the diamine compound used in Example 1 and the monoethanolamine of Comparative Example 1 and the renewable energy at this time are as shown in Table 5 below.

Item Example 1 Etherdiamine compound 30wt% monoethanolamine (MEA) of Comparative Example 1 renewable energy
(GJ/tCO ₂ ) 2.8 4.3 Pressure (barg) 0 0.29 L/G(L/Nm ³ ) 5.67 4.52 CO ₂ regeneration rate 80 80

The embodiments of the present invention have been described above, but those skilled in the art can add, change, delete, or add components within the scope of the present invention as set forth in the claims. It will be said that the present invention can be variously modified and changed by the like, and this is also included within the scope of the present invention.

R1: absorption reactor S1: CO ₂ supply container
S2: CO ₂ storage cylinder P1: High pressure pressure transducer
PR1, PR2: Pressure regulator T1, T2: Thermometer
V1 ~ V6: Valve 1: Agitator
C01: Wet tower C02: Absorption tower
C03: Removal tower CW01, CW02: Constant temperature circulation device
HX01: Absorbent heat exchanger HX02: Reboiler heat exchanger
P01, P02: Absorbent pump P03: Reboiler pump
T01: Tank at the bottom of the stripping tower T02: Storage tank for the condenser

Claims (18)

Carbon dioxide absorbent comprising a diamine compound represented by the formula (1);
[Formula 1]

In Formula 1,
n is a repetition number that is an integer selected from 0 to 10,
R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted A C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,
R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a C6 to C30 aryl group,
R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, Or a substituted or unsubstituted C1 to C30 heteroaryl group. According to claim 1,
In Chemical Formula 1,
n is a repetition number that is an integer selected from 0 to 4
R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), or a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group,
R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,
R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C10 carbon dioxide absorbent, characterized in that a straight-chain or pulverized alkyl group. According to claim 1,
In Chemical Formula 1,
n is a repetition number which is any integer selected from 1 to 3,
R ¹ and R ² are the same or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t -Butyl group,
R ⁴ and R ⁵ One of them is a hydrogen atom, the other is a C1 to C10 alkyl group,
R ³ is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, or a t-butyl group. According to claim 1,
In Chemical Formula 1,
n is 1,
R ¹ and R ² are methyl groups,
R ³ is a carbon dioxide absorbent characterized in that it is a methyl group. According to claim 1,
The carbon dioxide absorbent is a carbon dioxide absorbent, characterized in that the aqueous solution containing the diamine compound represented by the formula (1). The method of claim 5,
Carbon dioxide absorbent, characterized in that the aqueous solution containing the diamine compound represented by the formula (1) contains 20 to 80% by weight of the diamine compound represented by the formula (1). Method for separating carbon dioxide using a carbon dioxide absorbent comprising a diamine compound represented by Formula 1 below;
[Formula 1]

In Formula 1,
n is a repetition number that is any integer selected from 0 to 10,
R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted A C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,
R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a C6 to C30 aryl group,
R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group, a substituted or unsubstituted C6 to C30 aryl group, Or a substituted or unsubstituted C1 to C30 heteroaryl group. The method of claim 7,
In Chemical Formula 1,
n is a repetition number that is an integer selected from 0 to 4
R ¹ and R ² are the same as or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), or a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group,
R ⁴ and R ⁵ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,
R ³ is a hydrogen atom, a substituted or unsubstituted C1 to C10 straight-chain or pulverized alkyl group, characterized in that the carbon dioxide separation method. The method of claim 7,
In Chemical Formula 1,
n is a repetition number which is any integer selected from 1 to 3,
R ¹ and R ² are the same or different from each other, and each independently an amine group (-NR ⁴ R ⁵ ), methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, or t -Butyl group,
R ⁴ and R ⁵ One of them is a hydrogen atom, the other is a C1 to C10 alkyl group,
R ³ is a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, or a t-butyl group. The method of claim 7,
In Chemical Formula 1,
n is 1,
R ¹ and R ² are methyl groups,
R ³ is a methyl group, characterized in that the separation method of carbon dioxide. The method of claim 7,
The separation method of carbon dioxide,
(a) an absorption step of absorbing carbon dioxide from a gas mixture containing carbon dioxide by using an aqueous solution containing a diamine compound represented by Formula 1 as a carbon dioxide absorbent; And
(b) a stripping step of stripping the carbon dioxide absorbed by the carbon dioxide absorbent; carbon dioxide separation method comprising a. The method of claim 11,
In step (a), the carbon dioxide separation method, characterized in that the carbon dioxide absorption temperature is 20 to 60 ℃. The method of claim 11,
In step (a), the carbon dioxide separation method, characterized in that the pressure when absorbing carbon dioxide is 1 to 20 atmospheres. The method of claim 11,
In step (a), the ratio of the carbon dioxide absorbent to the gas mixture containing the carbon dioxide (L/G) is 2 to 7 L/Nm ³ Carbon dioxide separation method, characterized in that. The method of claim 11,
Carbon dioxide separation method, characterized in that the temperature when removing carbon dioxide in step (b) is 80 to 100 ℃. The method of claim 11,
Carbon dioxide separation method characterized in that the carbon dioxide stripping in step (b) is carried out at 1 atmosphere. The method of claim 11,
After step (b), the carbon dioxide separation method characterized in that the carbon dioxide is removed and further performing a reuse step of performing steps (a) and (b) using the regenerated carbon dioxide absorbent. The method of claim 17,
The reuse step is a carbon dioxide separation method characterized in that it is repeatedly performed a plurality of times.

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