KR20150077028A - Carbon dioxide absorbent - Google Patents

Abstract

The present invention relates to a carbon dioxide absorbent and, more specifically, to a carbon dioxide absorbent, which comprises a low alcohol substituted with an aliphatic tertiary amine, piperazine, and at least one amine group. According to the present invention, a carbon dioxide absorbent with low dissociation energy and a large amount of carbon dioxide dissociated during the same time can obtain effects in reducing energy consumption, in comparison with the existing low amine-based absorbent. In addition, effects in reducing costs can be obtained with absorption capacity, rapid absorption speed, and strong performance of anti-deterioration, anti-corruption, etc., and capable of reducing a scale of equipment or the like with a small amount of an absorbent supplemented during usage.

Description

[0001] Carbon dioxide absorbent [0002]

More particularly, the present invention relates to a carbon dioxide absorbent comprising an aliphatic tertiary amine, piperazine, and a lower alcohol substituted with at least one amine group.

Methods for separating carbon dioxide from exhaust gases from chemical plants, power plants, and steelmaking processes include absorption, adsorption, separation membrane, and deep-sea cooling. Among them, the absorption method and the adsorption method are mainly used when the concentration of the emitted carbon dioxide is low.

The absorption method and the adsorption method are widely used industrially because they can selectively separate only some gases which are easily absorbed and adsorbed by the absorbent and the adsorbent. The adsorption method is widely used for purification of exhaust gas and gas separation because of its advantage of easy replacement of the absorbent because it uses a liquid phase absorbent. When the adsorption method requires a long period of time to change the adsorbent, It is used for gas separation in harsh conditions.

As the carbon dioxide absorbing agent, a low-amine-based system such as monoethanolamine, N-methyldiethanolamine, diethanolamine and the like is most widely used because the weakly alkaline amine absorbent chemically bonds with the acidic gas, carbon dioxide, The carbon dioxide is separated (stripped) and recovered, and the absorbent can be regenerated.

Conventionally, "ionic liquid system carbon dioxide absorbent derived from amide" (Korean Patent Laid-Open No. 10-2010-0100391) and "alkali carbonate carbon dioxide absorbent having added sterically hindered cyclic amine and carbon dioxide removing method using same" Korean Patent Publication No. 10-2011-0075196).

An object of the present invention is to provide a carbon dioxide absorbent which is excellent in absorption capacity and absorption rate for carbon dioxide and is resistant to deterioration and corrosion.

According to one aspect of the invention, 3 to 7 parts by weight of an aliphatic tertiary amine; 5 to 15 parts by weight of piperazine; 3 to 7 parts by weight of a lower alcohol substituted with at least one amine group; And 75 to 85 parts by weight of water can be provided.

In one embodiment, the aliphatic tertiary amine is represented by R ₁ R ₂ R ₃ N, wherein R ₁ , R _2, and R ₃ are each independently selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ hydro is selected from alkyl and hydroxy C ₁ -C ₄ haloalkyl, wherein said piperazine is from C ₁ -C ₄ alkyl, C ₁ -C ₄ hydroxyalkyl, C ₁ -C ₄ haloalkyl and C ₁ -C ₄ aminoalkyl And may be optionally substituted with 1-2 substituents selected.

In one embodiment, the aliphatic tertiary amine is at least one selected from methyldiethanolamine, dimethylmonoethanolamine, ethyldiethanolamine, diethylmonoethanolamine, triethylamine, and trivinylamine, Razin is preferably selected from the group consisting of piperazine, 1-methylpiperazine, 2-methylpiperazine, dimethylpiperazine, 2,5-dimethyl-piperazine, cis 2,6-dimethyl-piperazine, (2-aminoethyl) piperazine, 1- (2-hydroxyethyl) piperazine, 1-amino-4-methyl At least one selected from piperazine, 1- (2-aminoethyl) -4-methylpiperazine, 1- (2-hydroxyethyl) -4-methylpiperazine and 2-aminoethyl-piperazine.

In one embodiment, the lower alcohol substituted with at least one amine group is selected from the group consisting of 2-amino-2-methyl-1-propanol, 2-isopropylamino-1-propanol, 2- (tert-butylamino) Amino-2-methyl-1,3-propanediol, and 2-amino-1-butanol. have.

In one embodiment, the carbon dioxide absorbent may further comprise 1 to 5 parts by weight of at least one additive selected from corrosion inhibitors, antioxidants, oxygen inhibitors, antifoaming agents and coagulation assistants.

According to the present invention, compared with the conventional low-amine-based absorbent, since the separation energy is low and the amount of carbon dioxide separated during the same time is large, the energy saving effect can be obtained. In addition, it has excellent absorption capacity and absorption rate for carbon dioxide, and has a strong performance against deterioration and corrosion, so that it is possible to reduce the amount of the absorbent to be supplemented at the time of use and reduce the size of the facility, thereby achieving cost reduction.

1 is a schematic view of an apparatus for absorbing carbon dioxide according to an embodiment of the present invention.
FIGS. 2 and 3 are graphs showing the measurement results of carbon dioxide absorption amount per unit time in Examples and Comparative Examples of the carbon dioxide absorbent according to the present invention.
4 is a graph showing the results of measurement of the heat of reaction occurring in the carbon dioxide absorption reaction of the carbon dioxide absorbent according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It is to be understood that the terms "comprises" or "having" in this application are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Hereinafter, embodiments of the carbon dioxide absorbent according to the present invention will be described in detail with reference to the accompanying drawings.

According to one aspect of the present invention, there can be provided a carbon dioxide absorbent comprising an aliphatic tertiary amine, piperazine, a lower alcohol substituted with at least one amine group, and water.

As used herein, the term "amine" refers to a compound in which the hydrogen atom of ammonia is substituted with a hydrocarbon group. When the hydrocarbon group is all an alkyl group, it is referred to as an "aliphatic amine ". The term "aliphatic tertiary amine" means an amine having a total of three hydrocarbon groups substituted with nitrogen atoms.

In one embodiment, the aliphatic tertiary amine is represented by R ₁ R ₂ R ₃ N, wherein R ₁ , R _2, and R ₃ are each independently selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ hydro hydroxyalkyl and C ₁ may be selected from -C ₄ haloalkyl, in another embodiment, the aliphatic tertiary amine is methyl diethanolamine, dimethyl monoethanolamine, ethyl diethanolamine, diethyl ethanolamine, triethylene Ethylamine, and trivinylamine.

The term "piperazine " used in the present invention means a heterocyclic compound (C ₄ H ₁₀ N ₂ ) containing two nitrogen atoms at the 1,4-position of a six-membered ring.

In one embodiment, the piperazine is substituted with 1 to 2 substituents selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ hydroxyalkyl, C ₁ -C ₄ haloalkyl and C ₁ -C ₄ aminoalkyl And in another embodiment the piperazine is selected from the group consisting of piperazine, 1-methylpiperazine, 2-methylpiperazine, dimethylpiperazine, 2,5-dimethyl-piperazine, Dimethyl-piperazine, 1,4-dimethyl-piperazine, trans 2,5-dimethyl-piperazine, 1- ethylpiperazine, aminoethylpiperazine, 1- (2- aminoethyl) piperazine, 1- (2-aminoethyl) -4-methylpiperazine, 1- (2-hydroxyethyl) -4-methylpiperazine and 2 -Aminoethyl-piperazine. ≪ / RTI >

The term " lower alcohol " used in the present invention means an alcohol having a small number of carbon atoms constituting an alcohol skeleton. In the present invention, an alcohol having 5 or less carbon atoms in the alcohol skeleton is referred to as a lower alcohol.

In one embodiment, the lower alcohol may have a backbone in a chain or branched form.

In one embodiment, the lower alcohol substituted with at least one amine group is selected from the group consisting of 2-amino-2-methyl-1-propanol, 2-isopropylamino-1-propanol, 2- (tert-butylamino) Amino-2-methyl-1,3-propanediol, and 2-amino-1-butanol. have.

The reaction formula of amine and carbon dioxide according to the type of amine used in the carbon dioxide absorbent is as follows.

Scheme 1

Scheme 2

The primary or secondary amine reacts directly with carbon dioxide to absorb 0.5 mol of carbon dioxide per mole of amine (see Scheme 1), while the tertiary amine acts as a base catalyst instead of directly with carbon dioxide, Carbon dioxide reacts to form hydrogen carbonate ions (HCO ₃ ^- ) (see Scheme 2). That is, when a tertiary amine is used, it is possible to absorb 1 mole of carbon dioxide per 1 mole of amine.

Table 1 below shows the results of comparison of the performance as a carbon dioxide absorbent according to a single absorbent.

Absorbent menstruum single
Absorbent Key Performance Secondary performance Absorption capacity
(mol CO ₂ / mol absorbent) Absorption rate
(m ³ / kmol · s) Reaction heat
(kJ / mol CO ₂ ) Deterioration corrosion MEA
0.5
7,600
84 Under Under Ethylene
Glycol water AEP 0.8 9,000 72 usually usually water MEDA 1.0 3.5 49 Great Great water

* MEA: monoethanolamine, AEP: aminoethylpiperazine, MDEA: methyldiethanolamine

As described above, when a tertiary amine is used, since it is possible to absorb 1 mol of carbon dioxide per 1 mol of amine, the equivalent amount of carbon dioxide absorbent to be added to absorb the same amount of carbon dioxide as that of the primary and secondary amine will be small.

However, Table 1, the third type, one of the methyl diethanol amine of the amine which can be used as the carbon dioxide absorbent as described in. However the advantage of a strong and heat of reaction and the vapor pressure in the degradation and erosion is low, the absorption rate 3.5 m ³ / kmol · s, which is significantly lower than other amine series. On the other hand, monoethanolamine or aminoethylpiperazine has excellent absorption rate, high reaction heat and vapor pressure, and is less resistant to deterioration and corrosion than tertiary amine.

Further, in the case of aminomethyl propanol (AMP), which is one of the lower alcohols substituted with at least one amine group exemplified in the present invention, the high hydrolysis characteristics due to the instability of the carbamate are caused by the volume of the alkyl chain group It has the advantages of fast reaction rate and low reaction heat, but it has high reaction heat and vapor pressure and low resistance to deterioration and corrosion.

Particularly, in the carbon dioxide capture and storage technology of the present invention, the main treatment cost is the energy cost consumed for separating the carbon dioxide in the absorbent by heating the absorbent at a high temperature in the separation tower, It accounts for 50 to 80% of energy costs. Since the heat generated by the carbon dioxide absorbent absorbs carbon dioxide is equal to the energy injected to separate the carbon dioxide from the absorbent, the selection of the carbon dioxide absorbent having a low reaction temperature is directly related to the performance of the absorbent.

In addition, recovering the reusable absorbent by separating the carbon dioxide from the absorbent absorbed carbon dioxide is also one of the indexes directly related to the performance of the absorbent.

Therefore, the present invention can provide complementary effects in terms of absorption capacity, absorption rate, reaction heat, vapor pressure and resistance to deterioration / corrosion, which are important indexes of performance evaluation of the carbon dioxide absorbent, And a carbon dioxide absorbent in which a recoverable heterogeneous amine and a lower alcohol are mixed.

Thus, in one embodiment, 3 to 7 parts by weight of an aliphatic tertiary amine; 5 to 15 parts by weight of piperazine; 3 to 7 parts by weight of a lower alcohol substituted with at least one amine group; And 75 to 85 parts by weight of water can be provided. In another embodiment, the carbon dioxide absorbent comprises 5 parts by weight of an aliphatic tertiary amine; 1 part by weight piperazine; 5 parts by weight of a lower alcohol substituted with at least one amine group; And 80 parts by weight of water.

In one embodiment, the composition may further comprise 1 to 5 parts by weight of at least one additive selected from the group consisting of a corrosion inhibitor, an antioxidant, an oxygen inhibitor, an antifoaming agent and an aggregation aid.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are illustrative of the present invention and the contents of the present invention are not limited to the following examples.

Manufacture of carbon dioxide absorbent

The compositions of Examples and Comparative Examples of the present invention prepared for the performance comparison of the carbon dioxide absorbent are shown in Table 2 below.

Composition (parts by weight) Example Comparative Example Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 MDEA 5 10 - - 5 10 AEP 10 10 - - 5 10 MEA - - 30 30 - - AMP 5 - - - 10 5 water 80 80 70 - 80 75 EG - - - 67 - - AC - - - 3 - -

* MEA: monoethanolamine; AEP: aminoethylpiperazine; MDEA: methyl diethanolamine; AMP: aminomethyl propanol; EG: ethylene glycol; AC: Acetate.

Comparison of absorption capacity of carbon dioxide absorbent

In order to compare the carbon dioxide absorbing ability of the carbon dioxide absorbent (Example 1 and Comparative Examples 1 to 5) prepared by the above examples, the amount of carbon dioxide absorbed by 1 mol amine was measured as the maximum saturation amount. The measurement results are shown in the graph of the absorption ability of carbon dioxide per hour shown in FIGS.

The carbon dioxide absorbent according to the embodiment of the present invention retained a carbon dioxide absorption amount (maximum saturation amount) of at least 0.7 mol per 1 mol of amine even after a sufficient time (after about 1 hour) elapsed, but the absorbent according to Comparative Examples 2 and 3 The maximum absorption capacity (maximum saturation amount) of 0.4 mol was observed, indicating a large difference in absorption capacity. In addition, the absorbent according to Comparative Examples 4 and 5 exhibited a maximum absorption of carbon dioxide of 0.6 mol, which was less than that of the carbon dioxide absorbent according to the embodiment of the present invention.

In addition, the carbon dioxide absorbent according to the embodiment of the present invention showed higher carbon dioxide absorption amount (maximum saturation amount) at 30 minutes than Comparative Example 1, and maintained carbon dioxide absorption amount (maximum saturation amount) at 0.75 mol or more even after 2 hours I could.

Comparison of Reaction Heat of Carbon Dioxide Absorbent Produced

The heat of reaction generated when the carbon dioxide absorbent (Example 1 and Comparative Examples 4 to 5) prepared by the above example absorbed 1 mol of carbon dioxide was measured in kJ units. The measurement results are shown in Fig.

The heat generated by the carbon dioxide absorbent absorbing the carbon dioxide is the same as the energy applied to separate the carbon dioxide from the absorbent. Therefore, the carbon dioxide absorbent having a low reaction heat has a low energy input to separate carbon dioxide from the absorbent than the absorbent having a high reaction heat.

Accordingly, it can be confirmed that the absorbent of the composition according to Example 1 has lower heat of reaction than that of the absorbent of the comparative example, so that it takes less energy to separate the carbon dioxide.

That is, as described above, according to the present invention, compared to the conventional amine-based absorbent, since the separation energy is low and the amount of carbon dioxide separated during the same time is large, the energy saving effect can be obtained. In addition, it has excellent absorption capacity and absorption rate for carbon dioxide, and has a strong performance against deterioration and corrosion, so that it is possible to reduce the amount of the absorbent to be supplemented at the time of use and reduce the size of the facility, thereby achieving cost reduction.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

Claims (5)

3 to 7 parts by weight of an aliphatic tertiary amine;
5 to 15 parts by weight of piperazine;
3 to 7 parts by weight of a lower alcohol substituted with at least one amine group; and
75 to 85 parts by weight of water.
The method according to claim 1,
Wherein the aliphatic tertiary amine is represented by R ₁ R ₂ R ₃ N, wherein R _1, R ₂ and R ₃ are each independently C ₁ -C ₄ alkyl, C ₁ -C ₄ hydroxyalkyl and C ₁ - C ₄ haloalkyl,
Said piperazine is a carbon dioxide absorbent optionally substituted with one to two substituents selected from C ₁ -C ₄ alkyl, C ₁ -C ₄ hydroxyalkyl, C ₁ -C ₄ haloalkyl and C ₁ -C ₄ aminoalkyl .
The method according to claim 1,
Wherein the aliphatic tertiary amine is at least one selected from methyldiethanolamine, dimethylmonoethanolamine, ethyldiethanolamine, diethylmonoethanolamine, triethylamine and trivinylamine,
Wherein the piperazine is selected from the group consisting of piperazine, 1-methylpiperazine, 2-methylpiperazine, dimethylpiperazine, 2,5-dimethyl- piperazine, cis 2,6- , Trans 2, 5-dimethyl-piperazine, 1 ethylpiperazine, aminoethylpiperazine, 1- (2-aminoethyl) piperazine, 1- (2-hydroxyethyl) At least one carbon dioxide selected from methylpiperazine, 1- (2-aminoethyl) -4-methylpiperazine, 1- (2-hydroxyethyl) -4-methylpiperazine and 2-aminoethyl- Absorbent.
The method according to claim 1,
The lower alcohols substituted with at least one amine group may be selected from the group consisting of 2-amino-2-methyl-1-propanol, 2-isopropylamino-1-propanol, 2- (tert- butylamino) Ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol and 2-amino-1-butanol.
The method according to claim 1,
1 to 5 parts by weight of at least one additive selected from corrosion inhibitors, antioxidants, oxygen inhibitors, defoamers and coagulant aids.

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