KR102487385B1 - Mixed absorbent for capturing carbon dioxide - Google Patents

Abstract

The present invention relates to an absorbent for capturing carbon dioxide that selectively absorbs carbon dioxide, and more particularly, is manufactured by mixing three or more other compounds, and absorbs and removes carbon dioxide even under conditions of low concentration of carbon dioxide and high concentration of oxygen. and a mixed absorbent for capturing carbon dioxide having excellent stripping rate and excellent durability of the absorbent.

Description

Mixed absorbent for carbon dioxide capture {MIXED ABSORBENT FOR CAPTURING CARBON DIOXIDE}

The present invention relates to an absorbent for capturing carbon dioxide that selectively absorbs carbon dioxide, and more particularly, to a mixed absorbent for capturing carbon dioxide in which three or more different compounds are mixed to improve carbon dioxide absorbency.

Various methods such as absorption, adsorption, membrane separation, and deep cooling have been proposed as carbon dioxide capture and storage technologies, but among these, the absorption method is suitable for large-capacity, low-concentration gas separation, so it is applied in most industries and power plants. this is easy The process of using monoethanolamine (hereinafter referred to as MEA) manufactured by ABB lummus Crest to capture CO ₂ by the absorption method is used in Trona, CA, USA and Shady Point (Shady Point, Oklahoma, USA).

However, while the absorption process using MEA as an absorbent has a fast reaction rate, a large amount of energy is consumed for carbon dioxide separation, a large amount of absorbent is used, and there is a problem of corrosion of the equipment due to the absorbent, so a new additive or absorbent that can solve this problem development is urgently needed.

As another example of the absorption method, a method of separating and recovering acid gases such as CO ₂ , H ₂ S, and COS in mixed gases discharged from steel mills and thermal power plants by using chemical reactions with alkanolamine aqueous solutions has also been extensively studied. has been applied in the field. Alkanolamines that have been widely used in the past include primary-type monoethanolamine (MEA), secondary-type diethanolamine (DEA), tertiary-type triethanolamine (TEA), N- There are N-methyl diethanolamine (MDEA) and triisopropanolamine (TIPA).

However, the above-described monoethanolamine (MEA) and diethanolamine (DEA) have been widely used because of their high reaction rate, but due to problems such as high corrosiveness, high renewable energy and deterioration of these compounds, It is known that there are difficulties in using it as an absorbent. In addition, N-methyldiethanolamine (MDEA) has low corrosiveness and low regeneration heat, but has a low absorption rate. Recently, studies on hindered amines such as aminomethylpropanol (2-amino-2-methyl-1-propanol, AMP) have been actively conducted as new alkanol amine-based absorbents. The characteristic of these hindered amines is their absorption capacity and acid gas selectivity is very high and the energy required for regeneration is low, but the absorption rate is relatively slow.

Korean Patent Registration No. 10-1746561

In consideration of the above points, an object of the present invention is to provide a mixed absorbent for capturing carbon dioxide with improved efficiency and durability in separating and recovering carbon dioxide from a mixed gas. In particular, it has a relatively fast absorption rate and a high regeneration rate that can be applied to exhaust gas composition such as LNG combined cycle power plants with a relatively low carbon dioxide concentration compared to coal-fired power plants, as well as providing an absorbent that can be used for a relatively large number of unreacted exhaust gases. want to do In addition, it is intended to provide a mixed absorbent for capturing carbon dioxide that is effectively used for flue gas composition such as LNG combined cycle power plants having a relatively high oxygen concentration compared to coal-fired power plants due to improved oxidative degradation.

The mixed absorbent for capturing carbon dioxide of the present invention to achieve the above object includes compounds represented by the following Chemical Formula 1 and Chemical Formula 2, and includes at least one compound among the compounds represented by Chemical Formula 3 and Chemical Formula 4 below. can do.

In Formula 1, a is a hydrocarbon group having 0 to 1 carbon atoms, b and c are hydrocarbon groups having 0 to 3 carbon atoms, and R ₁ and R ₂ are -(CH ₂ ) _f -H, -(CH ₂ ) _m It is any one selected from -NH ₂ , -CH-(CH ₃ ) ₂ and -C-(CH ₃ ) ₃ , where f and m are integers from 0 to 5.

The compound of Formula 1 is, for example, diethylenetriamine, 1,3-diamino-2-propanol, 1,5-diamino-3-pentane 1,5-diamino-2-pentanol, butylenediamine, pentamethylenediamine, hexamethylenediamine, bis(3-aminopropyl)amine ), tetraethylenepentamine, N-isopropylethylenediamine, N-isopropyl-1,3-propanediamine and 1,8-dia It is any one selected from mino-para-menthane (1,8-diamino-p-menthane), and among these, tetraethylenepentamine can be used most preferably.

In Formula 2, R ₃ is -(CH ₂ NHCH ₂ ) _g -, where g is an integer of 1 to 2.

The compound of Formula 2 is, for example, 1,4,7-triazacyclononane (1,4,7-triazacyclononane) and 1,4,7,10-tetraazacyclododicane (1,4,7,10 -tetraazacyclododecane), and preferably 1,4,7,10-tetraazacyclododecane (1,4,7,10-tetraazacyclododecane) can be used.

In Formula 3, d is a hydrocarbon group having 1 to 4 carbon atoms, and R ₄ is any one selected from -(CH ₂ ) _h -CH ₃ , -CH-(CH ₃ ) ₂ and -C-(CH ₃ ) ₃ , where h is an integer from 0 to 3.

The compound of Formula 3 is, for example, 2- (methylamino) ethanol (2- (methylamino) ethanol), 2- (ethylamino) ethanol (2- (ethylamino) ethanol), 2- (propylamino) ethanol ( 2-(propylamino)ethanol), 2-(isopropylamino)ethanol (2-(isopropylamino)ethanol), 2-(butylamino)ethanol (2-(butylamino)ethanol), 2-(tert-butylamino)ethanol (2-(tert-butylamino)ethanol), 3-(methylamino)propanol (3-(methylamino)propanol), 3-(ethylamino)propanol (3-(ethylamino)propanol), 3-(propylamino)propanol (3-(propylamino)propanol), 3-(isopropylamino)propanol (3-(isopropylamino)propanol), 3-(butylamino)propanol (3-(butylamino)propanol), 3-(tert-butylamino) Propanol (3-(tert-butylamino)propanol), 4-(methylamino)butanol (4-(methylamino)butanol), 4-(ethylamino)butanol (4-(ethylamino)butanol), 4-(propylamino) Butanol (4-(propylamino)butanol), 4-(isopropylamino)butanol (4-(isopropylamino)butanol), 4-(butylamino)butanol (4-(butylamino)butanol), 4-(tert-butylamino) ) Butanol (4- (tert-butylamino) butanol), 5- (methylamino) pentanol (5- (methylamino) pentanol), 5- (ethylamino) pentanol (5- (ethylamino) pentanol), 5- ( 5-(propylamino)pentanol, 5-(isopropylamino)pentanol, 5-(butylamino)pentanol and 5 -(tert-butylamino)pentanol (5-(tert-butylamino)pentanol) It may be any one selected from among. Among them, 2-(isopropylamino)ethanol may be preferably used.

In Formula 4, e is a hydrocarbon group having 0 to 3 carbon atoms, R ₅ is -(CH ₂ ) _i -H, or -CH-(CH ₃ ) ₂ , R ₆ is -H or CH ₃ , and R ₇ , R ₈ is -(CH ₂ ) _j -H, where i is an integer from 0 to 6, and j is an integer from 0 to 3.

The compound of Formula 4 is an alkanol amine-based absorbent, for example, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1 -Butanol (2-amino-2-methyl-1-butanol), 2-amino-2-methyl-1-pentanol (2-amino-2-methyl-1-pentanol), 3-amino-3-methyl- 1-butanol (3-amino-3-methyl-1-butanol), 4-amino-4-methyl-1-pentanol (4-amino-4-methyl-1-pentanol), N-methyl-2-amino -1-propanol (N-methyl-2-amino-1-propanol), N-ethyl-2-amino-1-propanol (N-ethyl-2-amino-1-propanol), N-isopropyl-2- Amino-1-propanol (N-isopropyl-2-amino-1-propanol), N-methyl-2-amino-1-butanol (N-methyl-2-amino-1-butanol), N-methyl-2- Amino-1-pentanol (N-methyl-2-amino-1-pentanol), N-isopropyl-2-amino-1-pentanol (N-isopropyl-2-amino-1-pentanol), 2-amino -1-propanol (2-amino-1-propanol), 2-amino-1-butanol (2-amino-1-butanol), 2-amino-3-methylbutanol (2-amino-3-methylbutanol), 2 -Amino-1-pentanol (2-amino-1-pentanol), 2-amino-1-hexanol (2-amino-1-hexanol), 3-amino-1-butanol (3-amino-1-butanol ), 4-amino-1-pentanol, 5-amino-1-hexanol, 3-amino-1-pentanol -1-pentanol), 3-amino-1-hexanol (3-amino-1-hexanol), 1-amino-2-propanol (1-amino-2-propanol), 1-amino-2-butanol (1 -amino-2-butanol), 1-amino-2-pentanol (1-amino-2-pentanol) and It may be any one selected from 1-amino-3-methyl-2-butanol (1-amino-3-methyl-2-butanol).

The mixed absorbent for capturing carbon dioxide of the present invention contains 5 to 15% by weight of the compound of Formula 1, 5 to 15% by weight of the compound of Formula 2, and 5 to 15% by weight of the compound of Formula 2, based on 100% by weight of the mixed absorbent for capturing carbon dioxide. 3 and at least one compound of Formula 4 may be included in an amount of 10 to 30% by weight, and the remaining amount of water may be included.

For example, the mixed absorbent for capturing carbon dioxide of the present invention includes tetraethylenepentamine and 1,4,7,10-tetraazacyclododicane, 2-(isopropylamino)ethanol and 2-amino-2-methyl It includes any one or more compounds selected from -1-propanol, but when the 2-(isopropylamino)ethanol is included, 2-(isopropyl)diethanolamine may be included. At this time, based on 100% by weight of the mixed absorbent for capturing carbon dioxide, the tetraethylenepentamine was 10% by weight, the 1,4,7,10-tetraazacyclododicane was 10% by weight, and the 2-(isopropyl Amino) ethanol may be 14 wt % to 21 wt %, and the 2-amino-2-methyl-1-propanol may be 10 wt % to 30 wt %. In addition, the total weight of the 2-(isopropylamino)ethanol and the 2-(isopropyl)diethanolamine is 20% by weight and 30% by weight based on 100% by weight of the mixed absorbent for capturing carbon dioxide, and the 2- (Isopropylamino)ethanol may be 14 wt% to 21 wt%, and the 2-(isopropyl)diethanolamine may be included at 6 wt% to 9 wt%.

Here, the component of the compound included in the mixed absorbent for capturing carbon dioxide may be included in an amount of 20 to 60% by weight based on 100% by weight of the mixed absorbent for capturing carbon dioxide, preferably based on 100% by weight of the mixed absorbent for capturing carbon dioxide. , and may include 50% by weight of the components of the compound and 50% by weight of the remaining water.

If the content range of the compound in the mixed absorbent for capturing carbon dioxide is out of the suggested range, the carbon dioxide absorption rate, absorption amount, stripping rate and stripping rate of the mixed absorbent for capturing carbon dioxide are reduced, and the durability of the absorbent is also reduced. As such, it is preferable to satisfy the above-described content range.

The mixed absorbent for capturing carbon dioxide of the present invention may further include a thiadiazole-based degradation inhibitor, wherein the thiadiazole-based degradation inhibitor is preferably dimercaptothiadiazole.

The thiadiazole-based deterioration inhibitor may be included in an amount of 0 or more and 1% by weight or less based on 100% by weight of the total carbon dioxide trapping mixed absorbent. If the content of the degradation inhibitor exceeds 1% by weight and is added in excess, problems such as carbon dioxide absorption and deterioration in regeneration performance of the absorbent occur.

The mixed absorbent for capturing carbon dioxide of the present invention absorbs carbon dioxide in a temperature range of 0 to less than 70°C, and removes it in a range of 70°C to 150°C.

The mixed absorbent for capturing carbon dioxide of the present invention has a carbon dioxide absorption and stripping pressure of 1 bar to 2 bar.

As the mixed absorbent for capturing carbon dioxide according to the present invention is applied to a wet carbon dioxide separation process through a carbon dioxide absorption and removal test and an oxidative deterioration test, the carbon dioxide absorption rate, absorption amount, stripping rate, It can be seen that not only the stripping rate but also the durability of the absorbent is excellent.

Therefore, the mixed absorbent for capturing carbon dioxide of the present invention, in consideration of the absorption rate, absorption amount, stripping rate, and stripping amount compared to commercial or existing absorbents even under low-concentration carbon dioxide exhaust gas conditions such as LNG combined cycle exhaust gas in addition to coal-fired power generation exhaust gas, capture facility's CAPEX and Capable of efficiently capturing carbon dioxide to reduce OPEX.

In addition, the mixed absorbent for capturing carbon dioxide of the present invention improves durability even under high-concentration oxygen exhaust gas conditions such as LNG combined cycle exhaust gas in addition to coal-fired power generation exhaust gas, and economical operation is possible by reducing loss of the absorbent due to entrainment.

1 is a schematic diagram briefly showing a carbon dioxide absorption and removal test apparatus.
2 is a schematic diagram schematically showing a reactor of an oxidative degradation test apparatus.

The mixed absorbent for capturing carbon dioxide according to the present invention will be described in more detail through Examples and Comparative Examples below.

Terms such as "consists of," "includes," or "adds" used in this specification should not be construed as necessarily including all of the various elements described in the specification, and some of them may not be included. It may be, and should be construed as being able to further include additional components.

In the present specification, for convenience of description, 'absorbent' is interchangeably named as 'carbon dioxide absorbent' or 'absorbent for capturing carbon dioxide'. In addition, the 'absorbent' of Examples 1 to 3 to be described below is also referred to as a 'mixed absorbent for capturing carbon dioxide'.

A mixed absorbent for capturing carbon dioxide in an aqueous solution having the composition shown in Table 1 below was prepared. Here, purified water was used as the solvent.

The following Examples 1 to 3 are mixed absorbents for capturing carbon dioxide in which three or more different compounds are mixed, and the mixed compound composition is 50% by weight based on 100% by weight of the entire mixed absorbent for capturing carbon dioxide, and the rest is purified. It was prepared with a compositional content of 50% by weight of water.

Comparative Examples 1 to 7 below are single-component carbon dioxide capture absorbents for comparison with the carbon dioxide capture mixed absorbents of Examples 1 to 3, or carbon dioxide capture in the form of a mixture of two different compounds. As an absorbent, the composition of the compound was 30% by weight based on 100% by weight of the total absorbent for capturing carbon dioxide, and the rest was prepared with a composition content of 70% by weight of purified water.

division absorbent density
(wt%) molarity
(M) Comparative Example 1 MEA 30 4.92 Comparative Example 2 MEA+DMTD 30:0.5 4.92 Comparative Example 3 TEPA 30 1.59 Comparative Example 4 IPAE+IPDEA 21:9 2.58 Comparative Example 5 AMP 30 3.37 Comparative Example 6 Pz 30 3.48 Comparative Example 7 TACD 30 1.74 Example 1 TEPA+IPAE+IPDEA+TACD 10:21:9:10 3.52 Example 2 TEPA+AMP+TACD 10:30:10 3.98 Example 3 TEPA+IPAE+IPDEA+AMP+TACD 10:14:6:10:10 3.66

In Table 1, MEA is monoethanolamine, DMTD is dimercaptothiadiazole as a thiadiazole-based deterioration inhibitor, and TEPA is tetraethylenepentamine, corresponding to the compound of Formula 1, IPAE is 2- (isopropylamino) ethanol (2- (isopropylamino) ethanol), which corresponds to the compound of Formula 3, and IPDEA is 2- (isopropyl) diethanolamine (2- (isopropyl) diethanolamine or N-isopropyl- 2,2′-iminodiethanol), AMP is aminomethylpropanol (2-amino-2-methyl-1-propanol) and corresponds to the compound of Formula 4, Pz is piperazine, and TACD is 1,4 , 7,10-tetraazacyclododecane (1,4,7,10-tetraazacyclododecane), which corresponds to the compound of Formula 2. As shown in Table 1, the mixed absorbents for capturing carbon dioxide of Examples and Comparative Examples A carbon dioxide absorption and removal test was performed to confirm the carbon dioxide absorption and removal efficiency of the absorbent for capturing carbon dioxide, and at this time, the carbon dioxide absorption and removal test apparatus as shown in FIG. 1 was performed.

In the carbon dioxide absorption and removal test, 50 g of the mixed absorbent for capturing carbon dioxide prepared in Examples 1 to 3, Comparative Example 1, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7 were used. Filled. A gas having a composition of 4% carbon dioxide and 96% nitrogen was injected and dispersed at a rate of 1.5 liters/minute into the reaction vessel through a tube with a porous diffuser under atmospheric conditions. Thereafter, the concentration of carbon dioxide in the outlet gas was continuously measured using a non-dispersive infrared analysis type carbon dioxide concentration meter to measure the absorption rate and amount of carbon dioxide. At a certain point in time when the absorbent was saturated to some extent by carbon dioxide, the temperature of the reaction vessel was raised to 70 ° C. to measure the rate and amount of carbon dioxide removed from the absorbent for 30 minutes. The results are shown in Table 2 below. shown in

division Absorption rate (min ^-1 ) Stripping speed (min ^-1 ) Absorption capacity (90 minutes) Removal amount (30 minutes) stripping rate g/kg M/M g/kg M/M g/kg M/M g/kg M/M % Comparative Example 1 2.7 0.012 1.2 0.0055 118 0.55 13 0.06 11 Comparative Example 3 3.5 0.050 1.0 0.014 183 2.6 28 0.40 15 Comparative Example 4 2.2 0.019 2.0 0.018 73 0.64 42 0.37 58 Comparative Example 5 2.4 0.016 1.3 0.0088 114 0.77 36 0.24 32 Comparative Example 6 3.0 0.020 0.5 0.0033 136 0.89 18 0.12 13 Comparative Example 7 3.2 0.042 1.6 0.021 172 2.2 50 0.65 29 Example 1 5.4 0.035 2.6 0.017 232 1.5 82 0.53 35 Example 2 6.0 0.034 2.2 0.013 260 1.5 83 0.47 32 Example 3 5.8 0.036 2.6 0.016 245 1.5 84 0.52 34

As shown in Table 2, the absorbents for capturing carbon dioxide according to Examples 1 to 3 were superior to the absorbents for capturing carbon dioxide of Comparative Examples in terms of carbon dioxide absorption rate, stripping rate, absorption capacity, stripping amount, and stripping rate. In addition, in order to examine the degrees of oxidative degradation of the absorbents for capturing carbon dioxide of the Examples and Comparative Examples prepared as shown in Table 1, an oxidative degradation test was performed using the oxidative degradation test apparatus shown in FIG. 2.

Specifically, in the oxidative degradation test, 0.7 liter of the absorbent for capturing carbon dioxide prepared in Examples 1 to 3 and Comparative Examples 1 to 7 was filled in a 1 liter glass reaction vessel contained in a water tank set at 60 ° C. Gas with a composition of 98% oxygen (O ₂ ) and 2% carbon dioxide (CO ₂ ) is injected and dispersed at a rate of 100 mL/min through a tube with a porous diffuser into the reaction vessel through a humidifier. made it Thereafter, 1 mL of the absorbent was collected at intervals of 50 to 100 hours for 1,200 hours and analyzed using gas chromatography. The analysis results obtained at this time are shown in Table 3 below.

division degree of oxidative degradation
(wt%/hr) Boiling point (℃) Comparative Example 1 3.8 170 Comparative Example 2 0.34 170 Comparative Example 3 2.9 340 Comparative Example 4 2.7 172 Comparative Example 5 1.5 165 Comparative Example 6 2.2 146 Comparative Example 7 1.8 284 Example 1 2.4 - Example 2 2.2 - Example 3 1.9 -

The degree of oxidative deterioration is a value representing the amount of degraded absorbent per hour, and the smaller the value, the better the durability. Referring to [Table 2], as in Comparative Example 1 and Comparative Examples 3 to 7, the degree of oxidative degradation for each single component of the absorbent for capturing carbon dioxide was Comparative Example 1 (MEA) > Comparative Example 3 (TEPA) ≫ Comparative Example 6 ( Pz) ≒ Comparative Example 4 (IPAE+IPDEA) ≒ Comparative Example 7 (TACD) ≒ Comparative Example 5 (AMP). That is, Comparative Example 3 (TEPA), which has a significantly higher carbon dioxide absorption rate and absorption amount, is also superior to Comparative Example 1 (MEA) in terms of oxidative deterioration, and also Comparative Example 4 (IPAE+IPDEA), Comparative Example 5 (AMP), and Comparative Example 6 (Pz) and Comparative Example 7 (TACD) are also significantly superior to Comparative Example 1 (MEA). It can be seen that the deterioration degree is improved by 36% or more compared to monoethanolamine (MEA) of Comparative Example 1 as a conventional absorbent.

As in Comparative Example 2 of Table 3, when dimercaptothiadiazole (DMTD), a thiadiazole-based deterioration inhibitor, was mixed with the absorbent for capturing carbon dioxide at 0.5% by weight based on the total weight of the absorbent, the degree of oxidative degradation was greatly reduced.

Therefore, when 0.5% by weight of dimercaptothiadiazole (DMTD), a thiadiazole-based deterioration inhibitor, was mixed with the mixed absorbents for capturing carbon dioxide of Examples 1 to 3, based on the total weight of the absorbent, from Comparative Example 2 in Table 3 It can be inferred that the degree of oxidative degradation is greatly reduced.

And, as shown in Table 3, considering the boiling points of Comparative Examples 1 to 7, Comparative Example 3 (TEPA) and Comparative Example 7 (TACD) had the highest boiling points, so tetraethylenepentamine (TEPA) and It can be seen that the mixed absorbents for capturing carbon dioxide of Examples 1 to 3 containing all of 1,4,7,10-tetraazacyclododicane (TACD) are effective in preventing volatilization and entrainment.

Claims (1)

including tetraethylenepentamine and 1,4,7,10-tetraazacyclododicane;
Including any one or more compounds selected from 2- (isopropylamino) ethanol and 2-amino-2-methyl-1-propanol,
Based on 100% by weight of the total carbon dioxide capture mixed absorbent,
The 1,4,7,10-tetraazacyclododicane is 10% by weight,
The 2-amino-2-methyl-1-propanol is 10 to 30% by weight;
In the case of including the 2-(isopropylamino)ethanol, 2-(isopropyl)diethanolamine is included together,
The total weight of the 2-(isopropylamino)ethanol and the 2-(isopropyl)diethanolamine is 20% to 30% by weight,
The 2-(isopropylamino)ethanol is 14% to 21% by weight, and the 2-(isopropyl)diethanolamine is 6% to 9% by weight.

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