Carbon dioxide capturing agent comprising two kinds of amine compounds and carbon dioxide capturing method using same

Abstract

The present invention relates to a carbon dioxide capturing agent comprising two kinds of amine compounds and a carbon dioxide capturing method using same. The present invention enables an effective and economically sustainable CO2 capturing process while achieving an improved reaction rate.

Description

Carbon dioxide capturing agent comprising two kinds of amine compounds and carbon dioxide capturing method using the same The present invention relates to a carbon dioxide capture agent comprising two kinds of amine compounds and a carbon dioxide capture method using the same. Since the start of the Industrial Revolution in the 1750s, the concentration of greenhouse gases in the atmosphere has begun to increase rapidly due to the continuous emission of large amounts of greenhouse gases. Carbon dioxide, which accounts for the majority of these greenhouse gases emitted, causes global warming and climate change, so efforts are needed in the industry to reduce it. In particular, coal-fired power generation, which accounts for about 30% of CO2 emissions from all energy-related businesses, is known as the largest single source of emissions. Global CO2 emissions from coal-fired power plants reached a record 9.7 Gt in 2021, more than 100 million tons higher than the previous peak in 2018. In order to get on track for the Net Zero scenario by 2050, emissions from coal-fired power plants must decrease by an average of about 8% per year by 2030. Post-combustion CO2 capture technology is widely used in industries to reduce emissions by capturing CO2 from exhaust gases and releasing it into the atmosphere. Currently available CO2 capture technologies include adsorption, physical / chemical absorption, membrane separation, biological purification, and cryogenic separation. Among these, the chemical absorption process using amine aqueous solution is a mature process that has been developed since the 1930s, and has a market share of more than 60% in the carbon capture market due to its convenience of operation, fast CO2 absorption rate, high absorption capacity, and recycling ability. In addition, compared with other CO2 capture methods, it is a reasonable technology that is relatively inexpensive and can be easily applied to current power plants because CO2 can be directly extracted from flue gas. Accordingly, the chemical absorption process based on amine is the first method considered for large-scale CO2 capture such as coal-fired power plants. The present invention has been made to solve the above-mentioned problem, and one embodiment of the present invention provides a carbon dioxide capture agent comprising two kinds of amine compounds and a carbon dioxide capture method using the same. The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below. As a technical means for achieving the above-mentioned technical task, one aspect of the present invention provides a carbon dioxide capture agent comprising an amine mixture, wherein the amine mixture comprises a first amine compound comprising a tertiary amine; and a second amine compound comprising a secondary amine. The above first amine may be at least one selected from the group consisting of 3-dimethylamino-1-propanol (3DMA1P), N, N-methyl diethanolamine (MDEA), triethanolamine (TEA), Triisopropanolamine (TIPA), and combinations thereof. The above first amine may be 3-dimethylamino-1-propanol (3DMA1P). The second amine is Piperazine (PZ), Propylamine, Dipropylamine, Butylamine, Dibutylamine, Isobutylamine, 1,2-Dimethyl propylamine, Hexylamine, N,N-Dimethyl allylamine, Dimethylamino ethylamine, 1,3-diamino propane, Methylamino propylamine, N-Aminoethyl morpholine, Imino bis propylamine, 2-pipecoline, 2,4-lupetidine, N-Amino-4-pipecoline, 2-Piperidine ethanol, 4-Piperidinol, N-Methyl benzylamine, Dibenzylamine, Phenethylamine, Pyrazine, 2-Methyl pyrazine, 2-Methyl piperazine, 2,3-Lutidine, 2-Methyl-4-ethyl pyridine, 4-Alkyl pyridine, Picolinic It may be at least one selected from the group consisting of acid, 2-Aminonicotinic acid, 3-Amino pyridine, 3-Decyloxy propylamine, and combinations thereof. The above secondary amine may be piperazine (PZ). The above amine mixture may include the first amine compound and the second amine compound in a weight ratio of 2 to 15:1. The content of the above amine mixture may be 35 to 45 wt% based on 100 wt% of the total carbon dioxide capture agent. As a technical means for achieving the above-mentioned technical task, another aspect of the present invention provides a method for capturing carbon dioxide, comprising the steps of: preparing an absorption liquid including an amine mixture; contacting the absorption liquid with a gas or liquid including carbon dioxide; absorbing carbon dioxide from the gas or liquid; and desorbing the carbon dioxide; wherein the amine mixture includes a first amine compound including a tertiary amine, and a second amine compound including a secondary amine. The first amine compound may be 3-dimethylamino-1-propanol (3DMA1P), and the second amine compound may be piperazine (PZ). The above amine mixture may contain the first amine compound and the second amine compound in a weight ratio of 2 to 15:1. The content of the above amine mixture may be 35 to 45 wt% based on 100 wt% of the entire mixture. The above absorption step can be performed at a temperature of 300 to 330 K. The above absorbing step can be performed at a pressure of 1 to 10 kPa. The above detachment step can be performed at a temperature of 380 to 410K. The above detaching step can be performed at a pressure of 90 to 100 kPa. According to one embodiment of the present invention, the carbon dioxide capture agent can not only perform an effective and economically sustainable CO2 capture process, but also have a more advantageous effect in terms of reaction speed. The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims. Figure 1 is a flow chart illustrating a carbon dioxide capture method using a carbon dioxide capture agent according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a gas-liquid equilibrium experimental device used for CO2 equilibrium solubility experiment and absorption rate measurement of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 3 shows the results of measuring the CO2 equilibrium solubility value at a temperature of 313 K of a carbon dioxide capture agent according to one embodiment of the present invention and a carbon dioxide capture agent according to other literature. Figure 4a shows the results of measuring the CO2 equilibrium solubility value at a temperature of 313 K of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 4b shows the results of measuring the CO2 equilibrium solubility value at 393 K of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 5 shows the results of measuring the circulation capacity of a carbon dioxide capture agent according to one embodiment of the present invention. FIG. 6 is a schematic diagram of a wetted wall column (WWC) device used to measure the total mass transfer coefficient of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 7 shows the results of CO2 absorption flux measurement according to various partial pressures at a temperature of 313 K of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 8 shows the total mass transfer coefficient (K) at a temperature of 313 K of a carbon dioxide capture agent according to one embodiment of the present invention. G ) are the measurement results. FIG. 9 is a schematic diagram of a differential reaction calorimeter (DRC, Setaram) that measures the amount of heat generated when a carbon dioxide capture agent reacts with CO2 according to one embodiment of the present invention. Figure 10 shows the results of measuring the heat of absorption at a temperature of 313 K of a carbon dioxide capture agent according to one embodiment of the present invention. Figure 11 shows the results of measuring the sensible heat, latent heat, and absorption heat of a carbon dioxide capture agent according to one embodiment of the present invention. Fig. 12 is Q of MEA 30 reg This is a result of measuring the relative heat load of a carbon dioxide capture agent according to one embodiment of the present invention when the value is considered to be 100. FIG. 13 is a schematic diagram of a batch reactor used for sampling a carbon dioxide capture agent according to one embodiment of the present invention. Figure 14 is a carbon dioxide capture agent according to one embodiment of the present invention. 13 The molecular structure is illustrated with carbons numbered to indicate the chemical species of the corresponding peaks in the C NMR spectrum. Figure 15 is for the 3DMA1P-PZ-H2O-CO₂ system. 13 The peaks in the C NMR spectrum are depicted. Figure 16 shows the results of concentration measurement according to CO₂ loading of the product of the 3DMA1P-PZ-H2O-CO₂ system. Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. Example 1 After adding an amine mixture containing 3DMA1P and PZ in a weight ratio of 3:1, a total amount of 100 gr (103.5 ml) of an amine absorbent mixed with water was made and stirred for 60 minutes to prepare a 0.407 M carbon dioxide capture agent aqueous solution. (Hereinafter referred to as 3DMA1P 30 + PZ 10) Example 2 After adding an amine mixture containing 3DMA1P and PZ in a weight ratio of 4.3:1, a total amount of 100 gr (104.1 ml) of an amine absorbent mixed with water was made and stirred for 60 minutes to prepare a 0.402 M carbon dioxide capture agent aqueous solution. (Hereinafter referred to as 3DMA1P 32.5 + PZ 7.5) Example 3 After adding an amine mixture containing 3DMA1P and PZ in a weight ratio of 7:1, the total amount of amine absorbent mixed with water was made 100 gr (104.7 ml), and stirred for 60 minutes to prepare a 0.397 M carbon dioxide capture agent aqueous solution. (Hereinafter referred to as 3DMA1P 35 + PZ 5) Example 4 After adding an amine mixture containing 3DMA1P and PZ in a weight ratio of 15:1, a total amount of 100 gr (105.3 ml) of an amine absorbent mixed with water was made and stirred for 60 minutes to prepare a 0.393 M carbon dioxide capture agent aqueous solution. (Hereinafter referred to as 3DMA1P 37.5 + PZ 2.5) Comparative Example 1 It was manufactured in the same manner as Example 1, except that 30 wt% of MEA was added instead of the amine mixture. (hereinafter referred to as MEA 30) Comparative Example 2 It was manufactured in the same manner as Example 1, except that 40 wt% of 3DMA1P was added instead of the amine mixture. (Hereinafter referred to as 3DMA1P 40) Experimental Example 1: Measurement of Equilibrium CO₂ Solubility The gas-liquid equilibrium experimental apparatus used for the CO₂ equilibrium solubility experiment and absorption rate measurement is shown in Fig. 2. The supply gas of the gas-liquid equilibrium apparatus used 99.99 vol% CO₂, and was injected into the reactor after being preheated in the reservoir. The experimental temperature was maintained using an oven, and the experiment was conducted at 313 K and 393 K, which are the temperatures of general absorption and stripping towers. The volume of the reactor was 200 mL, and 110 g of the collector was used. The stirring speed was maintained at 300 RPM to increase the contact area between the collector and the gas. The gas preheated in the reservoir was injected into the reactor, and the operation was repeated when the pressure inside the reactor reached equilibrium. As a result, the experiment was terminated when the pressure of the gas in the reactor and the reservoir were the same and no more gas was injected, and the CO₂ loading value was calculated by applying the equations below. Since the experimental condition is carbon dioxide in the combustion exhaust gas emitted at normal pressure, the absorption amount was calculated using the ideal gas state equation by assuming the compression factor of CO₂ as 1. Equilibrium partial pressure of carbon dioxide in the reactor After absorption equilibrium is reached as in Equation (1-1), the equilibrium pressure First pressure in It can be expressed as a value minus . (1-1) The number of moles of carbon dioxide injected is the initial pressure (P) of the supply as in Equation (1-2). Si ) after injection of carbon dioxide into the reactor (P ST ) minus the volume of the feeder (V) S ) is multiplied and divided by RT again to obtain the result by applying the ideal gas state equation. When equilibrium is reached, the number of moles of carbon dioxide in the gas phase of the reactor is given by the final pressure of the reactor (P) as in Equation (1-3). RT) is the initial pressure (P) of the reactor in a vacuum state. Ri ) minus the reactor gas phase volume (V R ) is multiplied by RT and then divided by the ideal gas equation of state to obtain the result. Finally, the number of moles of carbon dioxide absorbed is obtained from the difference between the two values, as in Equation (1-4). (1-2) Supply (gas storage tank): (1-3) Reactor: (1-4) Number of moles of CO₂ absorbed: CO₂ loading is the number of moles of carbon dioxide absorbed by the capture agent. Can amine molecule The value divided by can be expressed as the absorption capacity and is expressed as Equation (1-5). (1-5) At equilibrium, CO₂ solubility is an important parameter that indicates the CO₂ capture performance of a capture agent and the maximum amount of CO₂ that a liquid solution can absorb at a specific temperature and CO₂ partial pressure. In this experiment, the CO₂ equilibrium solubility values of 30 wt% MEA aqueous solution at 313 K were first measured according to the partial pressure, and the obtained data were compared with the literature data to demonstrate the validity of the device. The results are consistent with the literature data, as shown in Fig. 3. After demonstrating the reliability of the experimental apparatus under identical operating conditions, the equilibrium CO₂ solubilities of single 3DMA1P and 3DMA1P+PZ mixed absorbers were measured at temperatures of 313 K and 393 K under various CO₂ partial pressures. Figures 4a and 4b show the equilibrium CO₂ solubilities of the absorbers containing amine mixtures at 313 K and 393 K, respectively, and Table 1 summarizes the experimental results. Referring to Fig. 3, all the collectors showed an increase in equilibrium CO₂ solubility as the CO₂ partial pressure increased. Referring to Fig. 4a, the equilibrium CO₂ solubility showed a tendency to increase as the PZ content increased at the same pressure at low pressure, but when the equilibrium was completely reached, in the case of the 3DMA1P 40 collector, the CO₂ loading The value is 0.885, and for 3DMA1P 30 + PZ 10 collectors, it is reduced to about 0.866. This is related to the CO₂ loading value and molecular weight of a single amine. Theoretical CO₂ loading of 3DMA1P and PZ The values are 1 each, but according to the literature, 3DMA1P is about 0.89 and PZ is about 1.1, so PZ is larger. However, the molecular weight of 3DMA1P is 103.16 g / mol and PZ is 86.136 g / mol, so as the ratio of PZ in the collector increases, the overall mole number of amine tends to increase, and accordingly, CO₂ loading The values show a decreasing trend. To support this claim, CO₂ loading The units were converted into values and shown in Table 1. The total amount of CO₂ absorbed was found to increase as the ratio of PZ increased. Figure 4b shows the equilibrium CO₂ solubility at high temperature of 393 K. As the ratio of PZ increases, the CO₂ loading The opposite result of increasing values was observed. This can be explained by the vapor pressure measurement results shown in Table 2 of Experimental Example 7 below, and it can be inferred that the CO₂ loading value decreases due to loss of the collector because the volatility increases as the PZ ratio decreases. [Table 1] Experimental Example 2: Measurement of Circulating Capacity The circulation capacity is an important parameter that determines the height of the absorption tower in the CO₂ capture process. The loading value when the capture agent absorbs CO₂ at 313 K is called rich CO₂ loading, and the loading value when the capture agent regenerates at 393 K is called lean CO₂ loading. The difference between them is called the circulation capacity. The circulation capacity was used to verify the absorption and regeneration performance of the capture agent. The circulation capacity is expressed by Equation (2-1). (2-1) Cyclic capacity = Rich loading - Lean loading The loading value was determined at each temperature and partial pressure using the origin plot. Figure 5 shows a comparison of the calculated cyclic capacity values. The cyclic capacity of commercialized MEA 30 is 0.301 was calculated. 3DMA1P 40, 3DMA1P 37.5+PZ 2.5, 3DMA1P 35+PZ 5, 3DMA1P 32.5+PZ 7.5, and 3DMA1P 30+PZ 10 showed cyclic capacities 36, 48, 50, 22, and 20% higher than MEA 30, respectively. In addition, as the PZ content increased, it showed a tendency to increase and then decrease, but the cyclic capacities of all the collectors were higher than MEA 30, which means that the size of the absorption tower in the process can be reduced, and it can be confirmed that the reboiler heat duty is reduced by having lower sensible heat. Experimental Example 3: Measurement of the total mass transfer coefficient The total mass transfer coefficient of the collector was measured using a wetted wall column (WWC) device. The configuration of the WWC device is shown in Fig. 6. The WWC consists of a stainless steel tube with a height of 90 mm and an outer diameter of 12.6 mm. The column is surrounded by glass, and a double jacket is formed by two other glass walls, and water circulates between them to transfer heat. At this time, the temperature was maintained constant at 313 K using a thermostatic bath. The liquid collector flows at a flow rate of 150 mL / min, and the supply gas flows at a flow rate of 5 L / min from the bottom. After the collector and gas come into contact and react, the gas is discharged from the top and the collector is discharged from the bottom. The CO₂ injection concentration was changed from 3 vol% to 9 vol% for the experiment. The gas concentration was continuously analyzed using a non-dispersive infrared (NDIR) gas detector. The CO₂ concentrations at the inlet and outlet obtained through the NDIR also provide information on the CO₂ partial pressure. Total mass transfer coefficient (K G ) was calculated in the following order: The amount of CO₂ absorbed at the gas-liquid interface and mass flux ) is the driving force K G It was calculated by multiplying K. Since it is difficult to obtain the concentration of CO₂ at the interface, G Equilibrium partial pressure of CO₂ was used. (3-1) The pressure difference, or driving force, can be expressed using the log mean pressure difference. (3-2) and The values are data obtained from actual experiments. The value is not considered for the case of a capture medium that is not saturated with CO₂. Therefore, K G can be expressed as follows. (3-3) Mass flux can be calculated using the exposed area of the liquid film and the absorption rate (q). (3-4) In this formula d h is the hydraulic diameter including the tube diameter (d) and the liquid film thickness (f), and h is the height of the column. Hydraulic diameter (d h ) was calculated as follows. (3-5) The thickness (f) of the liquid film can be calculated using the following equation. (3-6) The viscosity and density required for the above equation were measured at 313 K using a viscometer (Brookfield, DV-II+PRO) and a density meter (Anton paar, DMA 4500M). The physicochemical properties of the 3DMA1P-PZ-H2O mixed collector are described in Table 2 below. As a result, K G is the log average driving force of CO₂ partial pressure as in Equation (3-3). About the plot can be determined by analyzing linear regression. The CO₂ loading value and cyclic capacity of a single 3DMA1P solution gave relatively high results, but the CO₂ absorption rate is slow due to the characteristics of tertiary amines, so it is too slow to be used as a collector alone. Therefore, PZ was mixed to improve the absorption rate, and the mass transfer coefficient of the 3DMA1P+ PZ collector was measured to compare the absorption rates. The absorption rate of the collector is a very important parameter that determines the height of the tower in the CO₂ capture process, and the measurement of the total mass transfer coefficient shows the result. The CO₂ absorption flux of the 3DMA1P+PZ mixed collector was measured at 313 K with various CO₂ concentrations (3, 6, 9, and 12 vol%) using a wetted wall column apparatus. The CO₂ unloaded collector was used in this experiment. The CO₂ absorption flux of the collector as a function of CO₂ partial pressure is shown in Fig. 7. MEA 30, 3DMA1P 40, and all mixed collectors showed higher absorption flux than MDEA 40, and 3DMA1P 30 + PZ 10 collector containing the highest amount of PZ showed the highest absorption rate. The overall mass transfer coefficient of the collector was obtained from the slope of the flux plot versus the log average partial pressure change. The overall mass transfer coefficient of the collector at 313 K (K G ) is shown in Fig. 8. The K of MEA 30 obtained in this experiment G is 2.056×10 3· mol·m -2· sec -1· kPa -1 . The KG of the 3DMA1P 32.5 + PZ 7.5 wt% and 3DMA1P 30 + PZ 10 collectors are 2.203 and 2.325 × 10, respectively. 3 ·mol·m -2 ·sec -1 ·kPa -1 It showed a higher value than MEA 30. The largest K G3DMA1P 30 + PZ 10 collector having MDEA 40 (0.231×10 3 ·mol·m -2 ·sec -1 ·kPa -1 ) 1000% of 3DMA1P 40 (0.301×10 3 ·mol·m -2 ·sec -1 ·kPa -1 ) 770% of MEA 30 (2.056×10 3 ·mol·m -2 ·sec -1 ·kPa -1 ) was found to be about 13% higher than the original value. Also, a single 3DMA1P is K better than MDEA. G It can be seen that the value is large, which can be explained by the difference in molecular structure as mentioned above. 3DMA1P 37.5 + PZ 2.5 collector has the lowest K among the mixed collectors. G , but shows about 400% improved results compared to the 3DMA1P 40 collector. This is a result that can prove that PZ acts as an activator in the mechanism suggested in the present invention. The activator improves the mass transfer of CO₂ at the interface as a CO₂ carrier. When an amine with high reactivity and small molecular size such as PZ is used as an activator, it is effective as a CO₂ transfer medium because it can easily move between the liquid membrane and the liquid bulk. As a result, PZ used as an activator in the present invention can significantly improve the CO₂ absorption rate of the 3DMA1P aqueous solution. Experimental Example 4: Measurement of heat of absorption The differential reaction calorimeter (DRC, Setaram) is a device that measures the amount of heat generated by the reaction of amine scavengers with CO₂. Figure 9 shows the configuration of the DRC device. 200 g of scavengers were injected into the measuring reactor and the reference reactor, each with a volume of 250 mL, and water was circulated between the reactor and the glass jacket through a circulator to maintain the reaction temperature at 313 K. The two reactors were connected to a single digital stirrer and stirred at 200 RPM to increase the contact area between the scavengers and the gas. In addition, the temperature of each scavenger was recorded in real time using a thermocouple. A Joule effect correction probe was installed in the measuring reactor. N₂ gas was injected into the reference reactor at a flow rate of 200 mL / min, and CO₂ 15 vol% (N₂balance) was injected into the measuring reactor at a flow rate of 200 mL / min using an MFC. The injection gas was supplied in the form of bubbles using a bubble injector. After passing through the collector, the CO₂ concentration was measured using gas chromatography (GC, Agilent 7890N) at a flow rate of 56 mL / min to calculate the amount of CO₂ dissolved in the collector. When the temperature difference (T) between the two reactors reached a constant value, the reaction was considered complete and the experiment was terminated. In order to measure the heat of reaction using DRC, the amount of CO₂ dissolved in the collector must first be calculated. The number of moles of CO₂ at the beginning of injection and the number of moles of CO₂ released after the reaction can be calculated by applying the ideal gas equation in Equations (4-1) and (4-2). Finally, the difference between the two moles is used to obtain the amount of CO₂ dissolved in the collector through Equation (4-3). (4-1) (4-2) (4-3) The total amount of CO₂ dissolved in the capture agent can be calculated by integrating the moles of CO₂ calculated from the above equation over time. Prior to the measurement of the heat of reaction, electrical compensation was performed to determine the reactor heat transfer coefficient (UA) (W / ℃) before and after the reaction of the collector and CO₂. The UA value can be determined through electrical compensation by the Joule effect. The electrical energy injected into the reactor is consumed through the reactor wall, and a temperature change curve is generated. At this time, the UA value can be determined through Equation (4-4) by integrating the area of the temperature change curve over time. (4-4) UA has different values depending on the change in chemical composition and the mixing of the sample. Therefore, the average of the UA values obtained by performing corrections 2 to 3 times before CO₂ is injected into the collector and after the reaction is completed should be obtained. (4-5) UA1 and UA2 are the heat transfer values before and after the reaction. Calculated UA average is the heat of reaction (Q) calculated by multiplying the area of the temperature change curve over time recorded during the CO₂ absorption reaction. r ) was derived. The reaction heat calculation formula is as follows. (4-6) The heat of absorption of the capture agents measured at a temperature of 313 K was compared using DRC, and the results are shown in Fig. 10. According to the results reported by Hadri et al. [EL HADRI, Nabil, et al. Aqueous amine solution characterization for post-combustion CO2 capture process. Applied Energy, 2017, 185: 1433-1449.], the heat of absorption of MEA 30 wt% aqueous solution was 85.13 kJ / mol. CO₂The validity of the values measured in the present invention is demonstrated, so that the results obtained by the apparatus and method used in this experiment are reliable. The maximum value of the heat of absorption is MEA 30 (85 kJ / mol CO₂ ), the lowest value was MDEA 40 (52.9 kJ / mol CO₂ ) is similar to MDEA 40. In the case of 3DMA1P 40, it has a value similar to MDEA 40. The 3DMA1P and PZ mixed collector is 59.2~64.8 kJ / mol. CO₂ As the ratio of PZ increases in the range, the heat of absorption also tends to increase. This shows that the heat of absorption of the mixed collector increases as the ratio of PZ, which has two primary amino groups that generate stable carbamate ions when reacted with CO₂, increases. On the other hand, tertiary amines MDEA and 3DMA1P produce bicarbonate and carbonate ions, so their heat of absorption is relatively low. In the case of 3DMA1P 30 + PZ 10, which has the highest heat of absorption among mixed collectors, it is 64.8 kJ / mol. CO₂ As a result, it can be concluded that the collector containing all amine mixtures is more effective for regeneration compared to MEA 30, which shows a value reduced by about 25%. Experimental Example 5: Energy consumption in the CO₂ capture process The energy consumption in the CO₂ capture process is commonly referred to as the reboiler heat duty, since the total energy for the regeneration of the capture agent is provided by the hot steam passing through the reboiler in the stripping tower. The reboiler heat duty can be described by the sum of the following three terms and was calculated using the equation presented by Oexmann et al. [OEXMANN, Jochen; KATHER, Alfons. Minimizing the regeneration heat duty of post-combustion CO2 capture by wet chemical absorption: The misguided focus on low heat of absorption solvents. International Journal of Greenhouse Gas Control, 2010, 4.1: 36-43.]. (5-1) In this formula is the sensible heat required to heat the collector to the regeneration temperature, represents the heat of vaporization, which directly indicates the amount of steam required in the reboiler for CO₂ desorption. is the heat of absorption generated when the capture agent reacts with CO₂, and the same amount of heat released from the exothermic reaction in the absorption tower must be provided in the stripping tower to reverse the absorption process and desorb CO₂. Consequently, a reboiler heat duty must be provided for the regeneration of the CO₂-loaded capture agent in the CO₂ capture process. The equation presented by Oexmann et al. is as follows. (5-2) (Reboiler Heat = Sensible Heat + Heat of Vaporization + Heat of Absorption) The factors included in the above equation are the specific heat capacity , circulating capacity ( ), temperature of reboiler and absorption tower , molar mass of the collector and CO₂ , mole fraction of amine in solution , heat of evaporation , partial pressure of water vapor and CO₂ under CO₂ desorption conditions , and the heat of reaction between the collector and CO₂ can be defined as . Some of these factors are not independent, so a holistic approach is needed that considers all contributing factors simultaneously. Reboiler heat duty was calculated using the equation (5-2) presented by Oxemann et al. Figure 11 shows the sensible heat, latent heat, absorption heat and their sum for each collector. As the content of PZ increased, the sensible heat and reaction heat tended to increase. Among them, 3DMA1P 32.5+PZ 7.5 showed the largest sensible heat value because it had a relatively high specific heat (Table 2) and low cyclic capacity. The heat of reaction was the highest in 3DMA1P 30+PZ 10, which had the highest PZ content, because the carbamate production reaction occurred more frequently as the PZ content increased. In the case of latent heat, there was no correlation with the content of PZ and all showed similar results to MEA 30. Q of MEA 30 reg is about 4.0 , and 3DMA1P 40, 3DMA1P 37.5+PZ 2.5, 3DMA1P 35+PZ 5, 3DMA1P 37.5+PZ 2.5 were 3.19, 3.30, 3.50, 3.78, and 3.59, respectively. All of them have reduced values compared to MEA 30. Fig. 12 shows the Q of MEA 30. reg When the value is considered as 100, the relative heat load is shown. 3DMA1P 40, 3DMA1P 37.5+PZ 2.5, 3DMA1P 35+PZ 5, and 3DMA1P 37.5+PZ 2.5 showed -20.3%, -17.4%, -12.5%, -5.5%, and -10.2% reduced heat load, respectively, compared to MEA 30. 3DMA1P 32.5+PZ 7.5 showed a higher heat load than 3DMA1P 30+PZ 10, which has the highest PZ content, which can be explained by the difference in the measured specific heat values in Table 2. As a result, all of the capture agents containing the amine mixture tested in this study have lower reboiler heat duty than MEA 30 and consume less energy for regeneration than MEA 30 in the CO₂ capture process, so they have economic advantages and can be judged to have potential in CO₂ capture. Experimental Example 6: 13 C Nuclear Magnetic Resonance Spectroscopy The species distribution of 3DMA1P+PZ aqueous solutions was determined using a BRUCKER AVANCE 400MHz NMR spectrometer. 13 C NMR measurements were performed at 293 K on CO₂-loaded mixed collectors. Spectra were acquired with a delay time of 2 min to obtain accurate peaks. 13 C NMR was obtained and the number of scans (NS) was 64. The CO₂-containing mixed collector was prepared using a batch reactor. Figure 13 shows the batch reactor used for sampling. 13The species of products formed when mixed amine aqueous solutions absorb carbon dioxide were identified and quantitatively evaluated through C NMR analysis in the 3DMA1P-PZ-H2O-CO₂ system. 13 The products that can be evaluated through C NMR spectra are PZ, protonated PZ (PZH + ), PZ carbamate(PZCOO - ), PZ dicarbamate(PZ(COO - )2), 3DMA1P, protonated 3DMA1P(3DMA1PH + ), bicarbonate(HCO 3- ), and carbonate(CO3 2- )am. 13 To indicate the chemical species of the corresponding peaks in the C NMR spectrum, each corresponding carbon was numbered as shown in Figure 14. Stacked for 3DMA1P-PZ-H2O-CO₂ system 13The peaks of each species in the C NMR spectrum are shown in Fig. 15. The peak appearing at δ=67.00 ppm is 1,4-dioxane used as a reference substance. The chemical shifts of the 3DMA1P peaks before CO₂ injection were δ=44.49, 55.87, 29.62, and 60.5 ppm, respectively, as indicated by the numbers 7, 8, 9, and 10 in Fig. 14, and in the case of PZ, it was shown at δ=45.46 ppm. After 10 minutes of reaction with CO₂, chemical shifts were observed in the peaks of carbamate (signal 4) and dicarbamate (signal 6) of PZ, which reacted with CO₂ first. After 30 minutes of reaction with CO₂, the chemical shift of the carbonate / bicarbonate peak appeared at a new peak at δ=163.46 ppm (signal 11). The peaks of carbonate and bicarbonate are indistinguishable due to the rapid proton exchange between them. This can be seen as an important clue to prove the assumption that CO₂ absorbed by free PZ in the previously presented mechanism (1-2) can be transferred to 3DMA1P and simultaneously reacts with water to form carbamate, and this carbamate reacts with 3DMA1P to form bicarbonate. As the CO₂ loading value gradually increases, the production of PZ carbamate and PZ dicarbamate also gradually increases until α=0.48 After 60 minutes of CO₂ absorption, the chemical shift of the PZ carbamate peak was no longer observed, and α=0.83 After 360 min, the chemical shift of the PZ dicarbamate peak was also not observed. On the other hand, the chemical shift of the carbonate / bicarbonate peak of signal 11 was observed until the reaction of the mixed collector and CO₂ was completed. The concentration changes of these three major products according to CO₂ loading are shown in Fig. 16. The concentration of PZ showed a tendency to gradually decrease until the reaction was completed, and in particular, the concentration of PZ gradually decreased at about α=0.32 at the beginning of the reaction with CO₂. It decreased rapidly until the concentration of carbonate and bicarbonate increased. After that, it can be confirmed that the increase in PZ / PZH+, PZ carbamate, and PZ dicarbamate decreases at the point where the concentration of carbonate and bicarbonate increases. This is the basis that can support the liquid behavior mechanism of the 3DMA1P+PZ mixed collector as mentioned above. Experimental Example 7: Physicochemical properties Physicochemical properties of solvents such as viscosity, density, pH, and vapor pressure are considered as some of the important parameters used in practical process applications. Among these, viscosity and density data are essential for column design of absorption and stripping columns and determination of reaction rate models. These data can be used to determine the diameter, velocity, and pressure drop of the column, and to calculate mass transfer correlations and mass transfer areas. The results of the measurement of physicochemical properties are shown in Table 2. Viscosity was measured using a viscometer (Brookfield, DV-II+PRO). The measurement temperature was maintained at 313 K (±0.1) by a water circulator. After washing with distilled water and acetone and drying, the next sample was injected. Density was measured using a density meter (Anton paar, DMA 4500M) with an accuracy of 0.00001 g / cm3. The measurement temperature was controlled at 313 K (±0.1) using the temperature control function of the density meter itself. Before density measurement, the density meter was washed and dried by pouring distilled water before use. pH is an important parameter in the amine mechanism. In the reaction of amine aqueous solution and CO₂, amines with stronger basicity can be protonated more quickly, which is consequently related to the CO₂ absorption capacity. pH was measured using a pH meter (Mettler Toledo, seven compact). The accuracy is ±0.002 and the measurements were made at room temperature. When capturing CO₂ with aqueous amine solutions, the use of new solvents to replace the lost amine reduces the cost-effectiveness of the process. The lower the vapor pressure of the capture agent, the better the CO₂ is maintained in the liquid state, and the less volatilized to the gaseous state, which makes it more efficient. Therefore, the measurement of the vapor pressure of aqueous amine solutions provides important information in the CO₂ capture process, and can be used to improve the efficiency and safety of the process. An automatic vapor pressure tester (GRABNER INSTRUMENTS, MiniVap VP Vision) was used to measure the vapor pressure. In addition, continuous measurements were made in the temperature range of 313-393 K. All physicochemical properties were measured three times to obtain reliable results, and the average values were obtained. The physicochemical properties of the capture agent can be applied as important parameters for design in the CO₂ capture process. Table 2 shows data summarizing the density, viscosity, pH, vapor pressure, and specific heat measurements according to the composition of the 3DMA1P+PZ system performed in the present invention. As the content of PZ increased, the density and viscosity increased. The pH tended to increase as the content of PZ increased, which means that the higher the amount of PZ, the stronger the basicity and the faster the protonation, which can accelerate the reaction rate with CO₂.

[0034] . Based on the pH analysis results, it can be one data that can prove the results of the overall mass transfer experiment conducted previously. The vapor pressure showed a tendency to decrease as the content of PZ increased at both 313K and 393K. When looking at the VLE experiment results, the CO₂ loading did not differ significantly at 313K. It can be seen that the values are significantly different at 393 K, which means that the influence of vapor pressure cannot be ignored. The results of the specific heat measurement showed that the single 3DMA1P 40 had the lowest value, and the mixed collectors containing PZ had higher values than the single 3DMA1P 40, but the mixed collector of 3DMA1P 30+PZ 10, which had the highest PZ content, showed the smallest result among them. [Table 2] Hereinafter, the present invention will be described in more detail. However, the present invention may be implemented in various different forms and the present invention is not limited to the embodiments described herein, and the present invention is only defined by the claims set forth below. In addition, the terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. Throughout the specification of the present invention, the term "including" a certain component does not exclude other components, but rather means that other components may be included, unless specifically stated otherwise. A first aspect of the present invention provides a carbon dioxide capture agent comprising an amine mixture. Hereinafter, a carbon dioxide capture agent according to the first aspect of the present invention will be described in detail. In one embodiment of the present invention, the carbon dioxide capture agent may include an amine mixture. The above amine mixture may include a first amine compound and a second amine compound. The above first amine compound may include a tertiary amine. The above first amine may be at least one selected from the group consisting of 3-dimethylamino-1-propanol (3DMA1P), N, N-methyl diethanolamine (MDEA), triethanolamine (TEA), Triisopropanolamine (TIPA), and combinations thereof. The above first amine may preferably be 3-dimethylamino-1-propanol (3DMA1P). Amines are classified according to the number of amine groups, and the most widely commercialized amine in the composition of carbon dioxide capture agents is monoethanolamine (MEA), a primary amine, which has the advantages of high absorption rate and low price. However, primary amines have a small absorption capacity and a mechanism for forming stable carbamates, so they have the disadvantage of requiring a lot of energy for regeneration. In addition, secondary amines have a fast absorption rate, but a small absorption capacity and a large regeneration energy. Tertiary amines have a large absorption capacity, a small regeneration energy, but a slow absorption rate. Therefore, the present invention has improved the disadvantages of carbon dioxide capture agents containing a single amine by producing a capture agent containing an amine mixture by mixing these amines rather than a single amine, thereby realizing the effects of having superior CO₂ absorption and desorption performance, reaction heat, and energy consumption. In particular, carbon dioxide capture agents based on tertiary amines have the effect of showing more improved energy efficiency than capture agents based on primary amines or secondary amines. Among these tertiary amines, it has been reported that 3-dimethylamino-1-propanol (3DAM1P) is more advantageous in CO₂ capture than the commonly used tertiary amine methyldiethanolamine (MDEA). N. El Hadri (EL HADRI, Nabil, et al. Aqueous amine solution characterization for post-combustion CO2 capture process. Applied Energy, 2017, 185: 1433-1449.) investigated the CO₂ loading values and absorption heats of 30 amines. The CO₂ loading values of MDEA and 3DMA1P were 0.74 and 0.85 (molCO₂ / molamine), respectively, and their absorption heats were similar values of -52.51 and -54.55 (H; kJ / mol of CO₂), showing that 3DMA1P has greater potential for CO₂ capture than MDEA. According to Liu(LIU, Sen, et al. Experimental evaluation of highly efficient primary and secondary amines with lower energy by a novel method for post-combustion CO2 capture. Applied energy, 2019, 233: 443-452.), the rGm (molar Gibbs energy change of proton combination with amine, kJ / mol) and rHm (molar reaction enthalpy of protonated amine dissociation into amine and proton, kJ / mol) values of 11 amines were calculated. The rGm values of the compared tertiary amines, MDEA, DEEA, N,N-dimethylethanolamine (DMEA), and 3DMA1P, are -49.15, -56.57, -53.26, -54.75, and the rHm values are 40.93, 43.25, 41.25, 39.89, showing that 3DMA1P is the most ideal amine among the compared tertiary amines. Also, the cyclic capacity is the largest among the compared amines and it is expected to have the best energy efficiency. According to Kadiwala (KADIWALA, Salim. Absorption Rates of CO2 in Aqueous and Non-Aqueous Amine Solutions and Solubility of CO2 in Aqueous Piperazine Solution. 2008. PhD Thesis. University of Regina.), 3DMA1P shows a higher reaction rate with CO₂ than MDEA. The molecular structure characteristics can determine the performance of amines for CO₂ capture and explain the high absorption capacity of 3DMA1P. The Hadri literature shows that tertiary amine 3DMA1P with four carbon chain length between two functional groups has faster reaction kinetics and lower heat of CO₂ absorption than parallel amines with two carbon chains. It also shows that CH2CH3 linked to nitrogen atom is more beneficial to CO₂ solubility than CH3 with the same carbon chain length in tertiary amines. The absorption rate of 3DMA1P may be faster than that of other tertiary amines, but it shows significantly slower results than that of primary and secondary amines and diamines due to the nature of tertiary amines. Accordingly, it is necessary to add primary and secondary amines to improve the absorption rate of 3DMA1P. Accordingly, the present invention may include an amine mixture comprising a first amine compound, which is a tertiary amine, and a second amine compound, which is a secondary amine. The second amine is Piperazine (PZ), Propylamine, Dipropylamine, Butylamine, Dibutylamine, Isobutylamine, 1,2-Dimethyl propylamine, Hexylamine, N,N-Dimethyl allylamine, Dimethylamino ethylamine, 1,3-diamino propane, Methylamino propylamine, N-Aminoethyl morpholine, Imino bis propylamine, 2-pipecoline, 2,4-lupetidine, N-Amino-4-pipecoline, 2-Piperidine ethanol, 4-Piperidinol, N-Methyl benzylamine, Dibenzylamine, Phenethylamine, Pyrazine, 2-Methyl pyrazine, 2-Methyl piperazine, 2,3-Lutidine, 2-Methyl-4-ethyl pyridine, 4-Alkyl pyridine, Picolinic It may be at least one selected from the group consisting of acid, 2-Aminonicotinic acid, 3-Amino pyridine, 3-Decyloxy propylamine, and combinations thereof. The above secondary amine may preferably include piperazine (PZ). Piperazine, a cyclic compound containing two secondary amine groups, is more resistant to deterioration and corrosion, has lower volatility, better CO₂ absorption capacity, and lower regeneration energy than conventional alkanol amines such as monoethanolamine, making it advantageous for CO₂ capture. The reaction of 3DMA1P aqueous solution activated by piperazine and CO₂ can be explained by the homogeneous activation mechanism or the shuttle mechanism. The CO₂ absorption of 3DMA1P+PZ aqueous solution can occur through the following reactions. (1) CO₂ + H2O H3O + + HCO3 - (2) HCO3 - + H2O H + + CO3 2- (3) PZ + H3O + PZH + + H2O (4) PZ + CO₂ PZ-CO₂ (5) PZ-CO₂ + 3DMA1P PZ + 3DMA1P-CO₂ (6) PZ-CO₂ + H2O PZCOO - + H3O + (7) PZCOO - + 3DMA1P + H2O 3DMA1PH + + HCO3 - + PZ (8) PZCOO - + CO₂ + H2O PZ(COO - )2+ H3O + (9) 3DMA1P + H3O + 3DMA1PH + + H2O (10) CO₂ + 3DMA1P 3DMA1P-CO₂ (11) 3DMA1P-CO₂ + H2O 3DMA1PH + + HCO3 - The dissociation of CO₂ to form bicarbonate and carbonate ions occurs as shown in Eqs. (1) and (2). PZ is protonated to form protonated PZ (Eq. (3)). The CO₂ absorbed by free PZ (Eq. (4)) can be transferred to 3DMA1P as shown in Eq. (5), and simultaneously undergoes a reaction with water to form carbamate (Eq. (6)), which then reacts with 3DMA1P to form bicarbonate (Eq. (7)). PZ has two amine groups and can theoretically react with 2 mol of CO₂, but the reaction in which the second amine group binds to the second CO₂ can be neglected (Eq. (8)). The effective free PZ can act as a homogeneous activator, although its concentration is very low, to transfer CO₂ to 3DMA1P, thereby accelerating the CO₂ absorption rate. The above amine mixture may include the first amine compound and the second amine compound in a weight ratio of 2 to 15: 1. For example, if the weight ratio is less than 2: 1, there may be a problem with increasing the CO2 absorption amount of the absorbent, and if it exceeds 15: 1, the CO2 absorption amount of the absorbent may be increased, but there may be a problem with the absorption rate being reduced. The content of the above amine mixture may be 30 to 50 wt% based on 100 wt% of the total carbon dioxide capture agent, and preferably, 35 to 45 wt%. If the content is less than 30 wt%, the amine content is low, so that the carbon dioxide absorption amount of the absorbent containing the amine is low, and there may be a problem with the circulating absorption amount (Rich amine - Lean amine, CO2 absorption amount in the absorption tower - CO2 content in the absorbent after CO2 removal in the stripping tower) indicating the performance of the subsequent capture process, and if it exceeds 50 wt%, the viscosity of the absorbent is high, so that there may be a problem with mass transfer and heat transfer during continuous CO2 absorption and regeneration, and there may be a problem with the operation of the continuous capture process. For example, the first amine compound can be at most 40 wt%, at most 37.5 wt%, at most 35 wt%, at most 32.5 wt%, at most 31 wt%, at most 30 wt%, or at least 29 wt%, and the second amine compound can be at least 10 wt%, at least 9 wt%, at least 7.5 wt%, at least 5 wt%, at least 2.5 wt%, or at least 1 wt%. The second aspect of the original is, A method for capturing carbon dioxide is provided, comprising: a step (S1) of preparing an absorbent liquid containing an amine mixture; a step (S2) of contacting the absorbent liquid with a gas containing carbon dioxide; a step (S3) of absorbing carbon dioxide from the gas; and a step (S4) of desorbing the carbon dioxide. Although detailed descriptions of parts that overlap with the first aspect of the present application have been omitted, the contents described for the first aspect of the present application may be equally applied even if the description is omitted for the second aspect. In one embodiment of the present invention, S1 may be a step of preparing an absorbent. The above absorbent liquid comprises an amine mixture, and the amine mixture may comprise a first amine compound and a second amine compound. The first amine compound and the second amine compound are as described above, but preferably, the first amine compound may be 3-dimethylamino-1-propanol (3DMA1P) and the second amine compound may be piperazine (PZ). The above mixture may contain the amine mixture in a weight ratio of 2 to 15: 1. If the weight ratio is less than 2: 1, there is a problem with increasing the CO2 absorption amount of the absorbent, and if it exceeds 15: 1, the CO2 absorption amount of the absorbent may be increased, but there may be a problem with the absorption rate being reduced. The above amine mixture may be 35 to 45 wt% based on 100 wt% of the entire mixture. If the content is less than 35 wt%, the amine content is low, so that the carbon dioxide absorption capacity of the absorbent containing the amine is low, and there is a problem with the circulation absorption capacity (Rich amine - Lean amine, CO2 absorption capacity in the absorption tower - CO2 content in the absorbent after CO2 stripping in the stripping tower) indicating the performance of the subsequent capture process. If it exceeds 45 wt%, the viscosity of the absorbent is high, so that there is a problem with mass transfer and heat transfer during continuous CO2 absorption and regeneration, and there may be a problem with the operation of the continuous capture process. The mixed solution may further include an accelerator, for example, Propylamine, Dipropylamine, Butylamine, Dibutylamine, Isobutylamine, 1,2-Dimethyl propylamine, Hexylamine, N,N-Dimethyl allylamine, Dimethylamino ethylamine, 1,3-diamino propane, Methylamino propylamine, N-Aminoethyl morpholine, Imino bis. propylamine, 2-pipecoline, 2,4-lupetidine, N-Amino-4-pipecoline, 2-Piperidine ethanol, 4-Piperidinol, N-Methyl benzylamine, Dibenzylamine, Phenethylamine, Pyrazine, 2-Methyl pyrazine, 2-Methyl piperazine, 2,3-Lutidine, 2-Methyl-4-ethyl pyridine, 4-Alkyl pyridine, Picolinic acid, It may include at least one selected from the group consisting of 2-Aminonicotinic acid, 3-Amino pyridine, 3-Decyloxy propylamine, and combinations thereof. In one embodiment of the present invention, the S2 may be a step of contacting a gas. The above gas may contain carbon dioxide. In one embodiment of the present invention, the S3 may be a step of absorbing carbon dioxide. The above S3 can be performed at a temperature of 300 to 330 K. If the temperature is less than 300 K, there may be a problem that a lot of energy is consumed to cool the exhaust gas in the pretreatment stage because the temperature is lower than that of the exhaust gas emitted during combustion, and if it exceeds 330 K, there may be a problem that the temperature of the absorbent is high, so that the temperature is high when the CO2 and the absorbent come into contact in the absorption tower, and the CO2 absorption amount of the absorbent is low. The above S3 can be performed at a pressure of 1 to 10 kPa. If the pressure exceeds 10 kPa, there may be a problem that a lot of energy is consumed to increase the pressure of the exhaust gas in the pretreatment stage because the pressure is higher than that of the exhaust gas emitted during combustion. In one embodiment of the present invention, the S4 may be a step of desorbing carbon dioxide. The above S4 can be performed at a temperature of 380 to 410 K. If the temperature is less than 300 K, there may be a problem that a lot of energy is consumed to cool the exhaust gas in the pretreatment stage because the temperature is lower than that of the exhaust gas emitted during combustion, and if it exceeds 330 K, there may be a problem that the temperature of the absorbent is high, so that the temperature is high when the CO2 and the absorbent come into contact in the absorption tower, and the CO2 absorption amount of the absorbent is low. There may be a problem that a lot of energy is consumed to cool the exhaust gas in the pretreatment stage because the temperature is lower than that of the exhaust gas emitted during combustion, and if it exceeds 330K, the temperature of the absorbent is high, so there may be a problem that the CO2 absorption amount of the absorbent is low because the temperature is high when it comes into contact with the CO2 and the absorbent in the absorption tower. There may be a problem that a lot of energy is consumed to cool the exhaust gas in the pretreatment stage because the temperature is lower than that of the exhaust gas emitted during combustion, and if it exceeds 330K, the temperature of the absorbent is high, so there may be a problem that the CO2 absorption amount of the absorbent is low because the temperature is high when it comes into contact with the CO2 and the absorbent in the absorption tower. The above S4 can be performed at a pressure of 90 to 100 kPa. If the pressure is less than 90 kPa, there may be a problem that the partial pressure of CO2 in the flue gas is low because the pressure is lower than that of the flue gas, resulting in a low CO2 absorption amount in the absorption tower. If it exceeds 100 kPa, there may be a problem that energy consumption is high in order to increase the pressure of the flue gas because the flue gas must be compressed. As the content of the secondary amine compound of the above absorbent increases, the CO2 loading can increase. As the content of the secondary amine compound of the above absorbent increases, the CO2 absorption rate can increase. As the content of the secondary amine compound in the above absorbent increases, the heat of absorption ((△H; kJ / mol of CO2)) may increase. According to an embodiment of the present invention, a carbon dioxide capture agent comprising two kinds of amine compounds and a carbon dioxide capture method using the same can not only perform an effective, economically sustainable CO2 capture process, but also have an improved reaction rate.

Claims

1. Containing an amine mixture, A carbon dioxide capture agent, wherein the amine mixture comprises a first amine compound including a tertiary amine; and a second amine compound including a secondary amine.

2. In paragraph 1, A carbon dioxide capturing agent, wherein the first amine is at least one selected from the group consisting of 3-dimethylamino-1-propanol (3DMA1P), N, N-methyl diethanolamine (MDEA), triethanolamine (TEA), Triisopropanolamine (TIPA), and combinations thereof.

3. In paragraph 1, A carbon dioxide capturing agent wherein the first amine is 3-dimethylamino-1-propanol (3DMA1P).

4. In paragraph 1, The second amine is Piperazine (PZ), Propylamine, Dipropylamine, Butylamine, Dibutylamine, Isobutylamine, 1,2-Dimethyl propylamine, Hexylamine, N,N-Dimethyl allylamine, Dimethylamino ethylamine, 1,3-diamino propane, Methylamino propylamine, N-Aminoethyl morpholine, Imino bis propylamine, 2-pipecoline, 2,4-lupetidine, N-Amino-4-pipecoline, 2-Piperidine ethanol, 4-Piperidinol, N-Methyl benzylamine, Dibenzylamine, Phenethylamine, Pyrazine, 2-Methyl pyrazine, 2-Methyl piperazine, 2,3-Lutidine, 2-Methyl-4-ethyl pyridine, 4-Alkyl pyridine, Picolinic A carbon dioxide capturing agent, wherein the agent is at least one selected from the group consisting of acid, 2-Aminonicotinic acid, 3-Amino pyridine, 3-Decyloxy propylamine, and combinations thereof.

5. In paragraph 1, A carbon dioxide capturing agent, wherein the second amine is piperazine (PZ).

6. In paragraph 1, A carbon dioxide capture agent, wherein the amine mixture comprises a first amine compound and a second amine compound in a weight ratio of 2 to 15:

1.

7. In paragraph 1, A carbon dioxide capture agent, wherein the content of the above amine mixture is 35 to 45 wt% based on 100 wt% of the total carbon dioxide capture agent.

8. A step of preparing an absorbent containing an amine mixture; A step of contacting the above absorbent with a gas or liquid containing carbon dioxide; A step of absorbing carbon dioxide from the above gas or liquid; and comprising a step of desorbing the carbon dioxide; A method for capturing carbon dioxide, wherein the amine mixture comprises a first amine compound including a tertiary amine and a second amine compound including a secondary amine.

9. In paragraph 8, The above first amine compound is 3-dimethylamino-1-propanol (3DMA1P), A method for capturing carbon dioxide, wherein the second amine compound is piperazine (PZ).

10. In paragraph 1, A method for capturing carbon dioxide, wherein the amine mixture comprises the first amine compound and the second amine compound in a weight ratio of 2 to 15:

1.

11. In paragraph 1, A method for capturing carbon dioxide, wherein the content of the above amine mixture is 35 to 45 wt% based on 100 wt% of the entire mixture.

12. In paragraph 8, A method for capturing carbon dioxide, wherein the above absorption step is performed at a temperature of 300 to 330K.

13. In paragraph 8, A method for capturing carbon dioxide, wherein the above absorbing step is performed at a pressure of 1 to 10 kPa.

14. In paragraph 8, A method for capturing carbon dioxide, wherein the above-mentioned detachment step is performed at a temperature of 380 to 410K.

15. In paragraph 8, A method for capturing carbon dioxide, wherein the above-mentioned detaching step is performed at a pressure of 90 to 100 kPa.

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