Carbon dioxide absorbent and carbon dioxide capture method using same

Abstract

The present invention relates to a carbon dioxide absorbent and a carbon dioxide capture method using same. The carbon dioxide absorbent according to the present invention has improved carbon dioxide absorption capacity and can be regenerated with low regeneration heat, thereby enabling carbon dioxide to be captured and the absorbent to be regenerated with high efficiency and at low cost.

Description

Carbon dioxide absorbent and carbon dioxide capture method using the same

[0001] The present invention relates to a carbon dioxide absorbent and a method for capturing carbon dioxide using the same.

[0002] As greenhouse gases emitted from the use of fossil fuels cause global warming, the importance of Carbon Dioxide Capture and Storage (CCS) technology, which sequesters carbon dioxide—the main culprit of global warming—from the atmosphere, is receiving attention.

[0003] CCS technology can be classified into capture technology, which separates and recovers carbon dioxide generated from the use of fossil fuels; transport technology, which moves the captured carbon dioxide to storage sites; and storage technology, which injects the transported carbon dioxide into the ground or ocean to sequester and monitor it. Since carbon capture costs account for 75 to 85% of the total cost of CCS technology, low-cost capture processes are crucial for the commercialization of CCS technology.

[0004] Carbon dioxide capture technologies can be classified into pre-combustion, post-combustion, and oxy-fuel combustion depending on the capture method. Pre-combustion technology is a technology that separates high-concentration carbon dioxide and produces hydrogen in conjunction with IGCC power generation, and long-term utilization is required when considering the commercialization of power generation technology. On the other hand, post-combustion technology is a technology that can be applied in conjunction with pulverized coal-fired power generation, which is currently used in most power plants, and since short-term application is possible, demonstration research is currently being actively conducted worldwide. Post-combustion technology is a method that removes nitrogen oxides, dust, and sulfur oxides from combustion flue gas (carbon dioxide concentration of 3–15%) and captures and separates carbon dioxide using a separation device before releasing it into the atmosphere.

[0005] Currently, among commercially available carbon dioxide capture technologies, there is a technology that uses monoethanolamine (MEA) absorbents. Monoethanolamine has the property of absorbing acidic gases very well and releasing them again when heated, and typically, a 30 wt% aqueous solution of monoethanolamine is used. Processes using monoethanolamine absorbents have the problem of consuming a large amount of energy to capture carbon dioxide. There is a need for a carbon dioxide absorbent with improved performance that can increase the amount and rate of carbon dioxide captured and reduce renewable energy consumption.

[0006] The present invention relates to a carbon dioxide absorbent and a method for capturing carbon dioxide using the same, and aims to provide a carbon dioxide absorbent with improved performance that can increase the amount and rate of carbon dioxide captured and reduce renewable energy consumption.

[0007] The present invention provides a carbon dioxide absorbent comprising a carbon dioxide absorption liquid and a carbon dioxide absorption promoter, and a method for capturing using the same.

[0008] The carbon dioxide absorbent according to the present invention has an enhanced carbon dioxide absorption capacity and can regenerate the absorbent with low regeneration heat, thereby enabling the capture of carbon dioxide and regeneration of the absorbent with high efficiency and low cost.

[0009] FIG. 1 is a schematic diagram showing a carbon dioxide capture system according to an embodiment of the present invention.

[0010] Figure 2 is a graph comparing the performance of carbon dioxide absorbent regenerative energy (specific reboiler duty, SRD) under small-capacity experimental conditions according to an embodiment of the present invention.

[0011] Figure 3 is a graph showing the carbon dioxide removal efficiency of a carbon dioxide absorbent at a reboiler temperature of 95°C according to an embodiment of the present invention.

[0012] Figure 4 is a graph comparing the performance of carbon dioxide absorbent regenerative energy (specific reboiler duty, SRD) at a reboiler temperature of 95°C according to an embodiment of the present invention.

[0013] Figure 5 is a graph showing the carbon dioxide removal efficiency of a carbon dioxide absorbent at a reboiler temperature of 100°C according to an embodiment of the present invention.

[0014] Figure 6 is a graph comparing the performance of carbon dioxide absorbent regenerative energy (specific reboiler duty, SRD) at a reboiler temperature of 100°C according to an embodiment of the present invention.

[0015] Figure 7 is a graph comparing the performance of carbon dioxide absorbent regenerative energy (specific reboiler duty, SRD) according to temperature and carbon dioxide concentration, according to an embodiment of the present invention.

[0016] Figure 8 is a graph showing the carbon dioxide removal efficiency of a carbon dioxide absorbent according to the reboiler operating temperature and carbon dioxide concentration, according to an embodiment of the present invention.

[0017] FIG. 9 is a graph showing the carbon dioxide removal efficiency of a carbon dioxide absorbent according to the G / L ratio in the reboiler operating temperature range of 80°C to 100°C, according to an embodiment of the present invention.

[0018] FIG. 10 is a graph comparing the performance of specific reboiler duty (SRD) of a carbon dioxide absorbent according to the promoter content of a carbon dioxide absorbent containing a carbon dioxide absorption promoter, in accordance with an embodiment of the present invention.

[0019] To achieve the above objective, a carbon dioxide absorbent is provided in one aspect of the present invention.

[0020] In one embodiment of the present invention, the carbon dioxide absorbent may include N-methyldiethanolamine (MDEA), hydroxyethylpiperazine (HEPZ), and piperazine (PZ).

[0021] In one embodiment of the present invention, the N-methyldiethanolamine may be included in an amount of 10% to 30% by weight relative to the total weight of the carbon dioxide absorbent.

[0022] In one embodiment of the present invention, the hydroxyethylpiperazine may be included in an amount of 1% to 10% by weight relative to the total weight of the carbon dioxide absorbent.

[0023] In one embodiment of the present invention, the piperazine may be included at a concentration of 0.5 m to 2.0 m relative to the total weight of the carbon dioxide absorbent.

[0024] In one embodiment of the present invention, the carbon dioxide absorbent may further include a carbon dioxide absorption promoter.

[0025] In one embodiment of the present invention, the carbon dioxide absorption promoter may include an organic metal salt.

[0026] In one embodiment of the present invention, the organometallic salt may comprise one or more selected from the group consisting of metal acetate, metal formate, metal propionate, and metal oxalate.

[0027] In one embodiment of the present invention, the metal may be Li, Na, or K.

[0028] In one embodiment of the present invention, the organometallic salt may be included in an amount of 1% to 20% by weight.

[0029] In one embodiment of the present invention, the carbon dioxide absorbent may further include water.

[0030] In another aspect of the present invention, a carbon dioxide capture method can be provided.

[0031] In one embodiment of the present invention, the method may include the step of absorbing carbon dioxide from a gas mixture containing carbon dioxide using the carbon dioxide absorbent; and the step of regenerating the carbon dioxide absorbent by removing the carbon dioxide absorbed by the carbon dioxide absorbent.

[0032] In one embodiment of the present invention, the step of absorbing carbon dioxide may be performed in a temperature range of 20°C to 60°C.

[0033] In one embodiment of the present invention, the step of regenerating the carbon dioxide absorbent can be performed at a temperature of 100°C or lower.

[0034] In one embodiment of the present invention, the carbon dioxide recovery method may further include the step of reusing a regenerated absorbent from which carbon dioxide has been removed.

[0035] One embodiment of the present invention is illustrated in the accompanying drawings. However, the present creative concept may be embodied in many other forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided to ensure that the present disclosure is thorough and complete and will sufficiently convey the scope of the present creative concept to those skilled in the art. Identical reference numerals denote identical components.

[0036] The terms used herein are intended to describe specific embodiments only and are not intended to limit the creative concept. The singular form used herein is intended to include the plural form including "at least one" unless the content clearly indicates otherwise. "At least one" should not be interpreted as limiting to the singular. As used herein, the term "and / or" includes any combination of one or more of the listed items. The terms "comprising" and / or "comprising" as used in the detailed description specify the presence of the specified features, regions, integers, steps, actions, components, and / or components, and do not exclude the presence or addition of one or more other features, regions, integers, steps, actions, components, components, and / or groups thereof.

[0037] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Furthermore, it will also be understood that terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning within the context of the relevant technology and the content of this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0038] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or cannot be anticipated may arise to the applicant or those skilled in the art. Accordingly, the appended claims, which may be filed and modified, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0039] In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0040] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0041] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is illustrated.

[0042] In the following embodiments, the x-axis, y-axis, and z-axis are not limited to three axes in an orthogonal coordinate system and can be interpreted in a broader sense that includes them. For example, the x-axis, y-axis, and z-axis may be orthogonal to each other, but they may also refer to different directions that are not orthogonal to each other.

[0043] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described consecutively may be performed substantially simultaneously or proceed in the reverse order of the description.

[0044] In one aspect, the present invention relates to a carbon dioxide absorbent, wherein the carbon dioxide absorbent may include a carbon dioxide absorption liquid and a carbon dioxide absorption promoter.

[0045] In one embodiment of the present invention, the carbon dioxide absorbent liquid may include an amine mixture and is an active ingredient that absorbs carbon dioxide by reacting directly with carbon dioxide within a carbon dioxide absorbent. In one embodiment, the carbon dioxide absorbent liquid may include two or more selected from the group consisting of N-methyldiethanolamine (MDEA), dimethylaminoethylamine (DMEA), triethanolamine (TEA), diethylaminoethanol (DEEA), hydroxyethylpiperazine (HEPZ), piperazine (PZ), 1-methylpiperazine (1-MePZ), and 2-methylpiperazine (2-MePZ).

[0046] The carbon dioxide absorbent of the present invention has a higher carbon dioxide capture capacity compared to conventionally used absorbents and can regenerate the carbon dioxide absorbent at a lower temperature, thereby reducing the amount of absorbent and regeneration energy required for the process.

[0047] FIG. 1 is a schematic diagram of a system for capturing carbon dioxide with a carbon dioxide absorbent of the present invention, removing carbon dioxide to recover carbon dioxide, and regenerating the absorbent.

[0048] In one embodiment of the present invention, the carbon dioxide absorbent of the present invention can be used in a carbon dioxide capture system comprising a carbon dioxide absorption unit (110) and a carbon dioxide absorbent regeneration unit (120).

[0049] In the carbon dioxide absorption unit (110), a mixed gas containing carbon dioxide is injected into the carbon dioxide absorption unit equipped with an absorbent to selectively absorb carbon dioxide. When carbon dioxide and the carbon dioxide absorbent are mixed, a rich solution containing the absorbent can be formed, and the rich solution can be supplied to the carbon dioxide absorbent regeneration unit (120) to remove carbon dioxide. The carbon dioxide absorbent regeneration unit can remove carbon dioxide from the rich solution and regenerate the carbon dioxide absorbent. The removed carbon dioxide can be discharged from the regeneration unit and supplied to the carbon dioxide recovery unit, or can be stored separately through various physicochemical methods.

[0050] In one embodiment of the present invention, the carbon dioxide capture system may further include a reboiler. In order to facilitate the removal of carbon dioxide in the carbon dioxide regeneration unit, carbon dioxide can be removed and the absorbent regenerated by heat supplied from the reboiler. The regenerated absorbent can be reused through a resupply line (200) to the carbon dioxide absorption unit, and can be cooled before being supplied to the carbon dioxide absorption unit.

[0051] The carbon dioxide absorbent according to the present invention enables carbon dioxide removal and absorbent regeneration under temperature conditions of 100°C or lower, thereby reducing the thermal energy required for the process.

[0052] Generally, monoethanolamine (MEA), a primary amine, is the most widely used because it has the highest basicity and the smallest equivalent weight. Diethanolamine (DEA), a secondary amine, and triethanolamine (TEA), N-methyldiethanolamine (MDEA), and triisopropanolamine (TIPA), a tertiary amine, are also used. In the case of MDEA, although it has low corrosiveness and regeneration heat, it has the disadvantage of a low absorption rate. Regarding absorption technology, the technology utilizing a monoethanolamine absorption solution is representative. Initially, the ABB Lummus process using a 20% monoethanolamine absorption solution was used; however, with the development of corrosion additives, the Fluor Daniel process using 30% MEA as the absorption solution was developed and is currently utilized as the representative standard amine process.

[0053] The present invention relates to a carbon dioxide absorbent comprising an amine mixture, and the carbon dioxide absorbent according to the present invention has the effect of increasing the amount of carbon dioxide captured and saving energy required for the regeneration of the absorbent.

[0054] In one embodiment of the present invention, the amine mixture may comprise two or more selected from the group consisting of N-methyldiethanolamine (MDEA), dimethylaminoethylamine (DMEA), triethanolamine (TEA), diethylaminoethanolamine (DEEA), hydroxyethylpiperazine (HEPZ), piperazine (PZ), 1-methylpiperazine (1-MePZ), and 2-methylpiperazine (2-MePZ). The amine compounds of the present invention are substances with relatively low biological / oxidative degradability, and their combination can improve the performance of carbon dioxide absorbents.

[0055] In one embodiment of the present invention, the carbon dioxide absorbent may comprise a combination of a tertiary amine compound and a secondary amine compound. For example, one or more selected from the group consisting of N-methyldiethanolamine (MDEA), dimethylaminoethylamine (DMEA), triethanolamine (TEA), and diethylaminoethanolamine (DEEA) may be adopted as the tertiary amine, and a mixture may be used in which one or more selected from the group consisting of hydroxyethylpiperazine (HEPZ), piperazine (PZ), 1-methylpiperazine (1-MePZ), and 2-methylpiperazine (2-MePZ) are adopted and mixed.

[0056] The amine compounds of the present invention are organic compounds having nitrogen bonded to one, two, or three carbons, and can be classified into primary amines (RNH2), secondary amines (R2NH), and tertiary amines (R3N) depending on the number of substituted hydrogen atoms. In the carbon dioxide absorption reaction of the amine absorbent, carbamates and bicarbonates are generated as intermediates; these can be dissociated to regenerate the amine absorbent and remove and recover the carbon dioxide. Generally, the reaction between the primary and secondary amines of the carbon dioxide absorbent and carbon dioxide can occur via two main mechanisms: 1) Carbamates are formed by a nucleus reaction in which electron-donating substances such as OH-, CN-, NH3, and H2O attack a region of low electron density in the counterpart substance (2RNH2 + CO2 = RNHCOO). - +RNH3 + ) and 2) the formed carbamate is converted to bicarbonate by hydrolysis with water (2RNH2+CO2+H2O=RNH3 + +HCO3 - +RNH2) can occur. In this case, the reaction between the amine and carbon dioxide can form a carbamate through a 2:1 molar reaction. Due to this absorption mechanism, carbon dioxide absorbents using primary and secondary amines exhibit a faster absorption rate but lower absorption capacity when the reaction proceeds more toward the carbamate reaction, whereas a slower absorption rate but higher absorption capacity when the reaction proceeds more toward the bicarbonate reaction. Furthermore, since carbon dioxide is released in the reverse order, high regeneration energy is required.

[0057] In the case of tertiary amines, carbamates are not formed because there are no amino hydrogen atoms, and they can absorb carbon dioxide to form bicarbonates. By capturing one carbon dioxide molecule per amine molecule, they can have higher absorption performance than primary and secondary amines and enable the realization of a carbon dioxide absorbent with low regeneration energy.

[0058] In one embodiment of the present invention, the amine mixture may be included in an amount of 10% to 80% by weight relative to the total weight of the absorbent. If the carbon dioxide absorbent liquid is less than 10% by weight, the carbon dioxide absorption efficiency is negligible and is undesirable, and if it exceeds 80% by weight, crystals may form within the absorbent or the loss rate of the absorbent due to deterioration may increase.

[0059] In a preferred embodiment of the present invention, the carbon dioxide absorbent comprises N-methyldiethanolamine (MDEA), a tertiary amine compound, and may comprise a mixture in which hydroxyethylpiperazine (HEPZ) and piperazine (PZ), which are secondary amine compounds, are mixed. N-methyldiethanolamine (MDEA) is a tertiary amine that has a high carbon dioxide absorption capacity, can reduce renewable energy consumption, and can possess thermal stability. Hydroxyethylpiperazine and piperazine can rapidly form carbamates with carbon dioxide, thereby increasing the carbon dioxide absorption rate. Hydroxyethylpiperazine and piperazine form carbamates with carbon dioxide to lower the initial carbon dioxide concentration, and N-methyldiethanolamine continuously absorbs carbon dioxide to increase the total amount of carbon dioxide absorbed. The above hydroxyethylpiperazine exhibits hydrophilicity due to the presence of hydroxyethyl groups, can be easily dissolved in an aqueous carbon dioxide absorbent, and can improve stability.

[0060] In one embodiment of the present invention, the piperazine and hydroxyethylpiperazine may each be included in a weight percent lower than that of N-methyldiethanolamine. If piperazine is added in a weight percent higher than that of N-methyldiethanolamine or diethylaminoethanol, the total carbon dioxide absorption amount is lowered, and the energy required to regenerate the absorbent may be increased.

[0061] In one embodiment of the present invention, the N-methyldiethanolamine may be included in an amount of 10% or more, 10% to 30%, 10% to 20%, 15% to 30%, 15% to 25%, 15% to 20%, 20% to 30%, or 20% to 30% based on the total weight of the carbon dioxide absorbent. If the N-methyldiethanolamine is included in the absorbent at less than 10% by weight, the amount of carbon dioxide captured may decrease, and the energy required to regenerate the absorbent may increase. Additionally, if it is included in an amount exceeding 30% by weight, the carbon dioxide absorption rate may decrease.

[0062] In one embodiment of the present invention, hydroxyethylpiperazine may be included in an amount of 1% or more, 1% to 10%, 1% to 8%, 1% to 5%, 1% to 3%, 3% to 10%, 3% to 8%, or 3% to 5% with respect to the total weight of the carbon dioxide absorbent. If the hydroxyethylpiperazine is included in the absorbent at less than 1% by weight, the total carbon dioxide absorption rate may be lowered, and if it is included at a level higher than 10% by weight, the energy required to regenerate the carbon dioxide absorbent may increase, and the energy required to regenerate the absorbent may increase.

[0063] In one embodiment of the present invention, the piperazine is present at an absorbent molal concentration of 0.5 m to 2.0 m, 0.5 m to 1.5 m, 0.5 m to 1.4 m, 0.5 m to 1.3 m, 0.5 m to 1.2 m, 0.5 m to 1.1 m, 0.5 m to 1.0 m, 0.8 m to 2.0 m, 0.8 m to 1.5 m, 0.8 m to 1.4 m, 0.8 m to 1.3 m, 0.8 m to 1.2 m, 0.8 m to 1.1 m, 0.8 m to 1.0 m, 0.9 m to 2.0 m, 0.9 m to 1.5 m, 0.9 m to 1.4 m, 0.9 m to 1.3 m, and 0.9 m to 1.2 m. It may be included at a molar concentration of 0.9 m to 1.1 m or 0.9 m to 1.0 m. If the piperazine is included at a molar concentration lower than 0.5 m, the total carbon dioxide absorption rate may be lowered, and if the piperazine is included at a molar concentration higher than 2.0 m, the energy required to regenerate the absorbent may be increased.

[0064] In one embodiment of the present invention, the carbon dioxide absorbent may further include a carbon dioxide absorption promoter, and the carbon dioxide absorption promoter may include an organic metal salt.

[0065] In one embodiment of the present invention, the organometallic salt may comprise one or more selected from the group consisting of metal acetates, metal formates, metal propionates, and metal oxalates. The metal may be Li, Na, or K, and in a preferred embodiment, the organometallic salt is potassium acetate. The organometallic salt containing a carboxyl group reacts with carbon dioxide within the carbon dioxide absorbent to form bicarbonates or carbonates, and can directly participate in carbon dioxide absorption. The organometallic salt present within the carbon dioxide absorbent can improve carbon dioxide absorption performance and facilitate maintenance of the absorbent. Furthermore, it can increase the carbon dioxide capture capacity and enable carbon dioxide removal even at low temperatures, thereby reducing the energy required for the regeneration of the carbon dioxide absorbent.

[0066] In one embodiment of the present invention, the organometallic salt may be included in an amount of 1% to 30% by weight, 5% to 25% by weight, 5% to 20% by weight, or 5% to 15% by weight. If the organometallic salt is included in an amount of less than 1% by weight, the improvement in carbon dioxide absorption efficiency is negligible, and if it is included in an amount of more than 30% by weight, it may reduce the stability of the amine compound.

[0067] In one embodiment of the present invention, the carbon dioxide absorbent may further include water. In the carbon dioxide absorbent containing water of the present invention, carbon dioxide can be dissolved in water and converted into carbonic acid, and the carbonic acid can increase the reactivity of the amine component of the present invention, for example, N-methyldiethanolamine or diethylaminoethanol, to form a bicarbonate.

[0068] In another aspect, the present invention can provide a method for capturing carbon dioxide using a carbon dioxide absorbent.

[0069] The carbon dioxide capture method of the present invention may include the step of absorbing carbon dioxide from a gas mixture containing carbon dioxide using a carbon dioxide absorbent; and the step of regenerating the carbon dioxide absorbent by removing the carbon dioxide absorbed by the carbon dioxide absorbent.

[0070] The step of absorbing carbon dioxide can capture carbon dioxide using the carbon dioxide absorbent described above. The step of absorbing carbon dioxide according to the present invention can be performed by injecting a carbon dioxide-containing gas into a carbon dioxide absorbent so that the absorbent can absorb the carbon dioxide within the contained gas. The carbon dioxide-containing gas is, for example, exhaust gas or flue gas (hereinafter referred to as "exhaust gas, etc."), and the exhaust gas, etc. may include waste gases formed as final products of power generation or processes in various industrial fields, and such exhaust gas, etc. may contain a large amount of carbon dioxide.

[0071] When absorbing carbon dioxide, the amount of carbon dioxide absorbed may increase as the temperature decreases and the pressure increases. In one embodiment, when absorbing carbon dioxide, the temperature may be performed in a temperature range of 0°C to 80°C, preferably in a temperature range of 20°C to 60°C, and the pressure may be performed at atmospheric pressure to about 80 atmospheres, preferably atmospheric pressure to 60 atmospheres.

[0072] The step of regenerating the carbon dioxide absorbent is a step in which carbon dioxide is removed from the absorbent that has absorbed carbon dioxide and the carbon dioxide absorbent is regenerated. More specifically, the absorbent can be regenerated by applying heat to the absorbent that has absorbed carbon dioxide, and the carbamate or bicarbonate within the absorbent can be decomposed by the heat, thereby removing the carbon dioxide and regenerating the absorbent. In one embodiment, the step of regenerating the carbon dioxide absorbent can be performed at a temperature of 120°C or lower, more preferably at a temperature of 100°C or lower.

[0073] In one embodiment of the present invention, the carbon dioxide recovery method may further include a step of reusing a regenerated absorbent from which carbon dioxide has been removed. The regenerated absorbent from which carbon dioxide has been removed can be reused in the step of absorbing carbon dioxide to be reused for carbon dioxide capture.

[0074]

[0075] The present invention will be explained in detail below through examples and experimental examples.

[0076] However, the embodiments and experimental examples described below are merely specific examples of the present invention in one aspect, and the present invention is not limited thereto.

[0077]

[0078] Example

[0079] <Example 1> Preparation of Carbon Dioxide Absorbent CV-S3

[0080] A carbon dioxide absorbent was prepared in an aqueous solution containing 25 wt% N-methyldiethanolamine (MDEA), 5 wt% hydroxyethylpiperazine (HEPZ), and 0.9 m piperazine (PZ).

[0081]

[0082] <Example 2> Preparation of a carbon dioxide absorbent with added carbon dioxide absorption promoter

[0083] A carbon dioxide absorbent was prepared by adding 15% by weight of potassium acetate as a carbon dioxide absorption promoter to the carbon dioxide absorbent prepared according to Example 1.

[0084]

[0085] <Example 3> Preparation of a carbon dioxide absorbent with added carbon dioxide absorption promoter

[0086] A carbon dioxide absorbent was prepared by adding 10% by weight of potassium acetate as a carbon dioxide absorption promoter to the carbon dioxide absorbent prepared according to Example 1.

[0087]

[0088] <Example 4> Preparation of a carbon dioxide absorbent with added carbon dioxide absorption promoter

[0089] A carbon dioxide absorbent was prepared by adding 5% by weight of potassium acetate as a carbon dioxide absorption promoter to the carbon dioxide absorbent prepared according to Example 1.

[0090]

[0091] <Comparative Example 1> Preparation of carbon dioxide absorbent

[0092] A carbon dioxide absorbent in the form of an aqueous solution containing 30% by weight of monoethanolamine (MEA) was prepared.

[0093]

[0094] <Test Example 1> Performance Evaluation of Small-Volume Batch Carbon Dioxide Absorbent

[0095] To evaluate the performance of the carbon dioxide absorbent CV-S3 prepared according to Example 1, the performance of the carbon dioxide capture capacity (CO2 loading or loading capacity) and specific reboiler duty (SRD) was evaluated using a solvent screening system (SSS) under the same experimental conditions.

[0096] The carbon dioxide absorption experiment was conducted up to the saturation level of the carbon dioxide absorbents of Example 1 and Comparative Example 1 according to the carbon dioxide sensor, and the carbon dioxide content was quantified by gravimetric measurement. Each carbon dioxide absorbent was 150g, the gas composition was 30% CO2 and 70% N2, and the gas flow rate was 1.0L / min.

[0097] Specific reboiler duty (SRD) evaluation was performed to assess the energy required for the regeneration of carbon dioxide absorbents. Regeneration is the process of removing carbon dioxide from absorbents that have absorbed carbon dioxide; the SRD evaluation considered the minimum (theoretical) and maximum (actual) values ​​by applying correction factors obtained from the theoretically required energy and actual experimental values.

[0098] To evaluate SRD, the experiment was conducted with a temperature gradient from 25°C to 100°C and a constant condenser temperature of 0°C, and nitrogen gas was injected during the experiment to promote the release of carbon dioxide from the saturated solvent. The results are shown in Table 1 and Figure 2 below.

[0099] Referring to Table 1, it was confirmed that the absorbent of Example 1 had a carbon dioxide capture capacity of 0.56 mol CO2 / mol amine. On the other hand, the absorbent of Comparative Example 1 showed a carbon dioxide capture capacity of 0.47 mol CO2 / mol amine, proving that the absorbent of Example 1 has superior carbon dioxide absorbent performance with a higher capture capacity than the absorbent of Comparative Example 1.

[0100] Classification Absorbent Components Carbon Dioxide Capture Capacity (in mol CO2 / mol amine) Comparative Example 1 MEA (30 wt%) 0.47 Example 1 MDEA / HEPZ / PZ (25 wt% / 5 wt% / 0.9 m) 0.56

[0101] Referring to Figure 2, regarding SRD performance, the absorbent of Example 1 showed a 15% reduction in SRD compared to Comparative Example 1, confirming that the energy required to regenerate the absorbent can be reduced compared to the MEA absorbent.

[0102] <Test Example 2> Performance Evaluation of a 95℃ Reboiler Large Capacity Carbon Dioxide Capture System

[0103] The performance evaluation of the large-capacity carbon dioxide capture system was tested under conditions similar to those of a general carbon dioxide capture system. The experiment was conducted up to the saturation level of the carbon dioxide absorbents of Example 1 and Comparative Example 1 according to the carbon dioxide sensor, and the carbon dioxide content was quantified by gravimetric measurement. Each carbon dioxide absorbent was 10 kg, the gas composition was 15% CO2 and 85% N2, the total gas flow rate was 14 L / min (CO2 = 2.10 L / min, N2 = 11.90 L / min), the absorbent flow rate was 1.0 L / min, and the G / L ratio was 14.

[0104] Specific reboiler duty (SRD) experiments were conducted with a solvent amount of 10 kg, gas composition of 50% CO2 and 50% N2, gas flow rate of 9.0 L / min, G / L ratios of 10, 20, 30, 40, and 50, and a reboiler temperature of 95 ℃. The results are shown in Table 2, Figures 3 and 4 below.

[0105] Referring to Table 2, the capture capacity of the absorbent showed different results from those confirmed in Test Example 1. It was confirmed that the absorbent of Example 1 had a capacity of 0.76 mol CO2 / mol amine. The capture capacity of the absorbent of Example 1 was measured to be 46% higher than that of the absorbent of Comparative Example 1. These results indicate that it has a very superior carbon dioxide capture capacity compared to the capacity of 0.52 mol CO2 / mol amine of the absorbent of Comparative Example 1.

[0106] Classification Absorbent Components Carbon Dioxide Capture Capacity (in mol CO2 / mol amine) Comparative Example 1 MEA (30 wt%) 0.52 Example 1 MDEA / HEPZ / PZ (25 wt% / 5 wt% / 0.9 m) 0.76

[0107] Referring to FIG. 3, which is a graph showing the carbon dioxide removal efficiency with respect to the G / L ratio at a reboiler operating temperature of 95°C, it was confirmed that the absorbent of Example 1 exhibited a 100% carbon dioxide removal efficiency at G / L ratios of 20 to 50, demonstrating superior carbon dioxide removal efficiency compared to Comparative Example 1. In particular, at a G / L ratio of 50, it was confirmed to exhibit performance five times better than Comparative Example 1. It was found that the carbon dioxide capture rate remained high even under operating conditions where the G / L ratio increased, and the carbon dioxide absorbent showed excellent regeneration performance at the corresponding temperature. The SRD data of the absorbent of Example 1 at 95°C is shown in FIG. 4. According to FIG. 4(a), the absorbent of Example 1 showed a 67% reduction rate at a G / L ratio of 10, exhibiting a significantly reduced SRD value compared to the absorbent of Comparative Example 1. Excellent SRD reduction was observed even at G / L 20 to 40 in FIGS. 4(b) to 4(d), and according to FIG. 4(e), it was confirmed that the absorbent of Example 1 showed superior absorbent regeneration performance compared to the absorbent of Comparative Example 1, with an SRD reduction rate of 36% even at G / L 50.

[0108]

[0109] <Test Example 3> Performance Evaluation of a 100℃ Reboiler Large Capacity Carbon Dioxide Capture System

[0110] Under the same conditions as Test Example 2 above, the reboiler temperature was set to 100°C to evaluate the performance of the carbon dioxide capture system. Similar to Test Example 2, the carbon dioxide absorption experiment was conducted until the carbon dioxide absorbents of Example 1 and Comparative Example 1 reached saturation according to the carbon dioxide sensor, and the carbon dioxide content was quantified by gravimetric measurement. Each carbon dioxide absorbent was 10 kg, the gas composition was 15% CO2 and 85% N2, the total gas flow rate was 14 L / min (CO2 = 2.10 L / min, N2 = 11.90 L / min), the absorbent flow rate was 1.0 L / min, and the G / L ratio was 14.

[0111] Specific reboiler duty (SRD) experiments were conducted with a solvent amount of 10 kg, gas composition of 50% CO2 and 50% N2, gas flow rate of 9.0 L / min, G / L ratios of 10, 20, 30, 40, and 50, and a reboiler temperature of 100 ℃. The results are shown in Table 3, Figures 5 and 6 below.

[0112] Referring to Table 3, it was confirmed that the absorbent of Example 1 had the same value as the result of Test Example 2 with a capacity of 0.76 mol CO2 / mol amine.

[0113] Classification Absorbent Components Carbon Dioxide Capture Capacity (in mol CO2 / mol amine) Comparative Example 1 MEA (30 wt%) 0.52 Example 1 MDEA / HEPZ / PZ (25 wt% / 5 wt% / 0.9 m) 0.76

[0114] Referring to FIG. 5, the carbon dioxide removal efficiency of the absorbent of Example 1 at a G / L ratio of 30 to 50 was higher than that of the absorbent of Comparative Example 1. In particular, at a G / L ratio of 50, it showed an efficiency of 98%, which was confirmed to be more than 2.4 times superior to the 40% efficiency of the absorbent of Comparative Example 1. When comparing the fact that the absorbent of Example 1 of the present invention showed more than 5 times the performance of the absorbent of Comparative Example 1 at a reboiler temperature of 95°C in the above test, and that it showed lower efficiency than Comparative Example 1 at a G / L ratio of 20, it suggests that the absorbents of the embodiments of the present invention exhibit even better performance than Comparative Example 1 at lower reboiler temperatures. The SRD data of the absorbent of Example 1 at 100°C is shown in FIG. 6. Referring to FIG. 6, it was confirmed that the absorbent of Example 1 showed a 59% increase in SRD compared to the MEA 30 wt% absorbent of Comparative Example 1 at a G / L ratio of 10, as shown in FIG. 6(a). The SRD also increased at G / L ratios of 20 and 30 in FIG. 6(b). These results are very different from the 95°C test results of Test Example 2, suggesting that the performance of the absorbent of the example of the present invention is superior at lower temperatures. On the other hand, the SRD decreased at a G / L ratio of 40 in FIG. 6(d) and a G / L ratio of 50 in FIG. 6(e), and it was confirmed that the SRD reduction rate of the absorbent of Example 1 at a G / L ratio of 50 was 16%, indicating superior performance compared to the absorbent of Comparative Example 1.

[0115]

[0116] <Test Example 4> Performance Evaluation of Carbon Dioxide Capture System by Carbon Dioxide Absorbent According to Temperature

[0117] Performance evaluation of a carbon dioxide capture system according to the temperature of the carbon dioxide absorbent according to Example 1 of the present invention was performed.

[0118] The performance evaluation at 100°C, in which the absorbent of Comparative Example 1 showed the best efficiency in the performance evaluations of Test Examples 2 and 3, and the performance evaluation of the absorbent of Example 1 at 90°C and 95°C were compared. The tests were performed under the conditions listed in Table 4, and the results are shown in Figures 7 and 8.

[0119] CO2 concentration (Volume%) Total gas flow (L / min) Liquid flow rate (L / min) G / L ratio 50 90.1850 40 90.1850 30 90.1850 20 90.1850 15 90.1850

[0120] Referring to Fig. 7, it was confirmed that the SRD according to each temperature of each absorbent decreased as the carbon dioxide concentration increased due to the increase in CO2 gas absorbed in the solvent. However, referring to Fig. 8, in the graph showing the carbon dioxide removal efficiency according to the reboiler operating temperature and carbon dioxide concentration, 100% removal efficiency was confirmed only when the carbon dioxide concentration was 15 volume% and 20 volume%, and it was confirmed that 100% removal was achieved at all concentrations only in the absorbent of Example 1 at 95℃. In particular, when the carbon dioxide concentration of the absorbent of Comparative Example 1 exceeded 20 volume%, the removal efficiency decreased sharply, reaching a minimum value of 42% when the carbon dioxide concentration was 50 volume%.

[0121] A performance evaluation of the carbon dioxide removal efficiency of the absorbent of Example 1 according to the G / L ratio was performed at a reboiler operating temperature of 80°C to 100°C, and the results are shown in Fig. 9.

[0122] It was confirmed that the absorbent according to Example 1 of the present invention exhibits a carbon dioxide removal efficiency of 90% or more at a G / L ratio in the range of 10 to 40 at 90°C or higher. It was also confirmed that at 85°C, removal of 90% or more is achieved at a G / L ratio of 10 to 30, suggesting that it is superior to the removal efficiency of Comparative Example 1 at a G / L ratio of 20 to 50 under all temperature conditions in which performance evaluation was performed.

[0123] The absorbent of Example 1 of the present invention can maintain a carbon dioxide capture rate even at a high G / L ratio, and the regeneration energy required for regenerating the absorbent can be significantly reduced compared to the absorbent of Comparative Example 1, and it exhibits superior efficiency at low temperatures, thereby reducing the energy required for the carbon dioxide capture process.

[0124]

[0125] <Test Example 5> Performance Evaluation of a Carbon Dioxide Capture System Using a Carbon Dioxide Absorbent Containing a Carbon Dioxide Absorption Promoter

[0126] Performance evaluation of a carbon dioxide capture system containing a carbon dioxide absorbent according to Examples 2 to 4 of the present invention was performed under the same conditions as Test Example 2. The results are shown in Table 5 and Figure 10.

[0127] Referring to Table 5, the absorbents of Examples 1 to 4 of the present invention exhibited superior capture capacity compared to Comparative Example 1, and in particular, Examples 2 to 4, which included a carbon dioxide absorption promoter, exhibited higher capture capacity. Examples 2 to 4 showed an increase of 32% or more compared to Comparative Example 1, and Examples 2 to 4 showed an increase of 15% or more compared to Example 1.

[0128] Classification Comparison Example 1 Example 1 Example 2 Example 3 Example 4 Capture Capacity (mol CO2 / mol amine) 0.46 0.53 0.63 0.60 0.61

[0129] Referring to FIG. 10, it was confirmed that the SRD of Examples 1 to 4 was reduced to 23% to 38% compared to Comparative Example 1. In particular, it was confirmed that the absorbents of Examples 2 to 4, to which a carbon dioxide absorption promoter was added, showed a higher SRD reduction rate than the absorbent of Example 1, to which no promoter was added. These results demonstrate that the potassium acetate contained in the carbon dioxide absorbent of the present invention acts as a promoter or catalyst within the carbon dioxide absorbent.

[0130] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0131] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

1. Comprising N-methyldiethanolamine (MDEA), hydroxyethylpiperazine (HEPZ), and piperazine (PZ), Carbon dioxide absorbent.

2. In Paragraph 1, The N-methyldiethanolamine is included in an amount of 10% to 30% by weight relative to the total weight of the carbon dioxide absorbent. Carbon dioxide absorbent.

3. In Paragraph 1, The hydroxyethylpiperazine is included in an amount of 1% to 10% by weight relative to the total weight of the carbon dioxide absorbent. Carbon dioxide absorbent.

4. In Paragraph 1, The piperazine is contained at a concentration of 0.5 m to 2.0 m with respect to the total weight of the carbon dioxide absorbent, Carbon dioxide absorbent.

5. In Paragraph 1, The above carbon dioxide absorbent further includes a carbon dioxide absorption promoter, and The above carbon dioxide absorbent is an organometal salt, Carbon dioxide absorbent.

6. In Paragraph 5, The above organometallic salt comprises one or more selected from the group consisting of metal acetates, metal formates, metal propionates, metal phosphates, and metal oxalates. Carbon dioxide absorbent.

7. In Paragraph 6, The above metal is Li, Na, or K, Carbon dioxide absorbent.

8. In Paragraph 5, The above organometallic salt is included in an amount of 1% to 20% by weight, Carbon dioxide absorbent.

9. In Paragraph 1, The above carbon dioxide absorbent further contains water, Carbon dioxide absorbent.

10. As a carbon dioxide capture method, The above method comprises the step of absorbing carbon dioxide from a gas mixture containing carbon dioxide using a carbon dioxide absorbent according to any one of claims 1 to 9; and, A method comprising the step of regenerating the carbon dioxide absorbent by removing carbon dioxide absorbed by the carbon dioxide absorbent. Carbon dioxide capture method.

11. In Paragraph 10, The step of absorbing carbon dioxide is performed in a temperature range of 20 ℃ to 60 ℃, Carbon dioxide capture method.

12. In Paragraph 10, The step of regenerating the carbon dioxide absorbent is performed at a temperature of 100°C or lower, Carbon dioxide capture method.

13. In Paragraph 10, The above carbon dioxide recovery method further includes the step of reusing a regenerated absorbent from which carbon dioxide has been removed. Carbon dioxide capture method.

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