A CO2 adsorbent suitable for treating hot flue gas, its preparation method and application

Abstract

This invention belongs to the field of gas separation and carbon capture technology, specifically relating to a CO2 adsorbent suitable for treating hot flue gas, its preparation method, and its application, particularly suitable for the efficient capture and separation of CO2 in medium- and high-temperature industrial hot flue gas systems. The adsorbent is a ternary eutectic solvent, with 4-methylimidazole (4MI) as the first hydrogen bond acceptor, 3-aminopropanol (3AP) as the hydrogen bond donor, and monoethanolamine (MEA) as the second hydrogen bond acceptor; wherein the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:3, and the mass of monoethanolamine (MEA) accounts for 20-40 wt% of the mass of the binary eutectic solvent composed of 4MI and 3AP. This invention solves the problem of decreased absorption capacity and inability to adapt to industrial hot flue gas scenarios of existing DES-type CO2 adsorbents at medium and high temperatures, achieving efficient CO2 capture in a temperature range of 20-100℃. Simultaneously, this adsorbent possesses characteristics of water resistance, good thermal stability, and excellent cycle performance, making it suitable for industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of gas separation and carbon capture technology, specifically relating to a CO2 adsorbent suitable for treating hot flue gas, its preparation method and application, especially suitable for efficient CO2 capture and separation in medium and high temperature industrial hot flue gas systems. Background Technology

[0002] Industrial flue gas emissions are one of the main sources of CO2. Most industrial flue gas temperatures fall within the medium-high temperature range of 20-100℃. Achieving efficient CO2 capture within this temperature range is of great significance for the goal of carbon neutrality. Due to its advantages such as designability, low volatility, and environmental friendliness, eutectic solvents (DES) have become a research hotspot in the field of CO2 capture and have been widely developed as CO2 adsorbents.

[0003] Existing DES-type CO2 adsorbents are mostly systems such as aromatic amine-polyol, choline salt-alkanolamine-water, imidazole-alkanolamine, and triamine salt-polyamine. The CO2 absorption performance of these adsorbents is generally significantly affected by temperature; as temperature increases, the CO2 absorption capacity shows a clear downward trend, making them unsuitable for medium- and high-temperature applications involving industrial hot flue gas. For example, the CO2 absorption capacity of 4-aminopyridine / ethylene glycol (1:3) DES is 0.60 mol / mol at 303.15 K, decreasing further when the temperature rises to 323.1 K. After 5 K, the absorption decreased to 0.28 mol / mol, a decrease of 53.3%; the absorption of imidazole / monoethanolamine (1:4) DES was 0.323 g / g at 303.15 K, which decreased to 0.294 g / g at 333.15 K, a decrease of 9.0%; the absorption of 1,5-diazabicyclo[4.3.0]non-5-ene / 2-imidazolidineone (2:1) DES was 0.299 g / g at 45 °C, which was only 0.085 g / g at 80 °C, a decrease of 71.6%. Even though the negative effects of temperature were mitigated by adding water in some systems, the absorption still decreased with increasing temperature. Moreover, the desorption rate increased at high temperatures, while the absorption performance decreased significantly, making it difficult to balance the adsorption efficiency at medium and high temperatures with industrial applicability.

[0004] To address the issue of CO2 absorption capacity decay in existing DES adsorbents at medium and high temperatures, developing a DES-type CO2 adsorbent with increased CO2 absorption capacity as temperature rises and adaptable to industrial hot flue gas at 20~100℃ has become an urgent technical challenge in the current carbon capture field. Summary of the Invention

[0005] (a) Technical problems to be solved The purpose of this invention is to provide a CO2 adsorbent suitable for treating hot flue gas, its preparation method, and its application. This invention solves the problems of the decreased absorption capacity of existing DES-type CO2 adsorbents at medium and high temperatures and their inability to adapt to industrial hot flue gas scenarios. It achieves efficient CO2 capture in a temperature range of 20~100℃. At the same time, this adsorbent has the characteristics of water resistance, good thermal stability, and excellent cycle performance, making it suitable for industrial applications.

[0006] (II) Technical Solution In a first aspect, the present invention provides a CO2 adsorbent suitable for treating hot flue gas. The adsorbent is a ternary eutectic solvent, with 4-methylimidazole (4MI) as the first hydrogen bond acceptor, 3-aminopropanol (3AP) as the hydrogen bond donor, and monoethanolamine (MEA) as the second hydrogen bond acceptor; wherein the molar ratio of 4MI to 3AP is 1:3, and the mass of monoethanolamine (MEA) accounts for 20-40 wt% of the mass of the binary eutectic solvent composed of 4MI-3AP.

[0007] Secondly, the present invention provides a method for preparing a CO2 adsorbent suitable for treating hot flue gas, comprising the following steps: S1. Raw material pretreatment: Place 4-methylimidazole (4MI), 3-aminopropanol (3AP), and monoethanolamine (MEA) in a vacuum drying oven and vacuum dry at 40-60℃ for 20-24 hours to remove moisture and volatile impurities from the raw materials for later use. S2. Preparation of binary eutectic solvent: Weigh the pretreated 4MI and 3AP in a molar ratio of 1:3 and add them to a container with a stirrer. Stir at 70-80℃ for 1.5-3h until the system forms a homogeneous, transparent and stable liquid to obtain the 4MI:3AP (1:3) binary eutectic solvent. S3. Preparation of ternary eutectic solvent: Add 20-40wt% (preferably 20wt%) of pretreated MEA to the above 4MI:3AP (1:3) binary eutectic solvent, and continue stirring at room temperature until a homogeneous, transparent and stable liquid is formed, thus obtaining a CO2 adsorbent suitable for treating hot flue gas.

[0008] Thirdly, the present invention provides the application of the above-mentioned CO2 adsorbent in capturing CO2 in hot flue gas.

[0009] The temperature of the hot flue gas is 20-100℃.

[0010] Fourthly, the present invention provides a method for capturing CO2 in hot flue gas, comprising: capturing CO2 in industrial hot flue gas at 20-100°C and normal pressure using the above-mentioned CO2 adsorbent.

[0011] (III) Beneficial Effects The ternary eutectic solvent adsorbent prepared by this invention, consisting of 4MI:3AP(1:3) + 20-40wt%MEA, overcomes the technical bottleneck of absorption capacity decay at high temperatures in existing DES adsorbents, making it suitable for industrial hot flue gas applications. Furthermore, this series of adsorbents exhibits excellent water resistance, thermal stability, and cycling performance. Specific technical effects are as follows: (1) CO2 absorption capacity increases significantly with increasing temperature at medium and high temperatures: The CO2 absorption capacity of this series of adsorbents shows a continuous increasing trend with increasing temperature in the range of 20~100℃; Among them, the preferred 4MI:3AP(1:3)+20-40wt%MEA adsorbent has an absorption capacity of 0.1533g CO2 / g DES at 20℃, which increases to 0.2172g CO2 / g DES at 100℃. The high temperature environment significantly promotes CO2 absorption and is perfectly suited for CO2 capture of industrial hot flue gas at 20~100℃; Under simulated flue gas conditions, the preferred adsorbent has an absorption capacity of 0.1333g CO2 / g DES at 20℃ and reaches 0.1872g CO2 / g DES at 100℃, still maintaining the core characteristic of increasing absorption capacity with increasing temperature.

[0012] (2) Excellent water resistance, simplifying the flue gas pretreatment process: In both pure CO2 system and simulated flue gas system, this series of adsorbents has good resistance to moisture. When the moisture content in the flue gas is ≤50wt%, the CO2 absorption capacity of the adsorbent only decreases slightly. There is no need to perform deep dehydration treatment on industrial flue gas, which greatly simplifies the flue gas pretreatment process and reduces the cost of industrial applications.

[0013] (3) Good thermal stability, meeting the requirements of adsorption-desorption industrial cycle: The initial thermal decomposition temperature of this series of adsorbents is 93℃, and they are completely decomposed at 220℃. Their decomposition temperature is much higher than the industrial desorption temperature (90℃). There is no solvent loss and the structure remains intact during the adsorption-desorption cycle. They can exist stably at medium and high temperatures.

[0014] (4) Excellent cycle performance and low industrial regeneration cost: Under the conditions of adsorption at 30℃ and desorption at 90℃, the CO2 absorption capacity of this series of adsorbents does not decrease significantly after 5 absorption-desorption cycles, and the desorption rate remains above 90%; among them, the preferred 20-40wt% MEA adsorbent has a stable absorption capacity of about 0.1683g CO2 / g DES after cycling, and the absorption-desorption process is highly reversible, which greatly reduces the industrial regeneration cost.

[0015] (5) Excellent physicochemical properties, which are conducive to industrial mass transfer: The adsorbents in this series are all uniform and transparent liquids with viscosity that decreases significantly with increasing temperature. They have high intermolecular mass transfer efficiency and density that changes linearly with temperature, making them easy to design and control in industrial processes. At the same time, the introduction of MEA improves absorption performance while reducing overall raw material costs.

[0016] (6) The preparation process is simple, environmentally friendly and cost-controllable: the preparation process of the adsorbent is carried out at room temperature, without the need for high temperature and high pressure conditions. The process is simple and easy to operate. The raw materials are non-volatile and environmentally friendly. It is suitable for large-scale industrial production and application. Attached Figure Description

[0017] Figure 1 The viscosity curves of the eutectic solvents of Examples 1, Comparative Examples 1, and Comparative Examples 8-9 as a function of temperature are shown.

[0018] Figure 2 The changes in CO2 absorption performance of 4MI:3AP (1:3) DES+20% MEA under different temperature conditions.

[0019] Figure 3 The changes in CO2 absorption capacity when using 4MI:3AP(1:3)+20% MEA to capture CO2 from flue gas with water contents of 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% at 30℃ and normal pressure.

[0020] Figure 4 The TGA curve of 4MI:3AP(1:3)+20% MEA DES under N2 protection during the process of heating from room temperature to 500℃.

[0021] Figure 5 The recycling performance results are for 4MI:3AP(1:3)+20% MEA DES.

[0022] Figure 6 The CO2 absorption capacity of five different mass ratios of 4MI-3AP:MEA eutectic solvent is shown.

[0023] Figure 7 The variation of CO2 absorption performance in simulated flue gas using 4MI:3AP(1:3) DES+20% MEA under different temperature conditions.

[0024] Figure 8 The study investigated the changes in CO2 absorption capacity when treating flue gas with moisture contents of 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% using a 4MI:3AP(1:3)+20% MEA solution under simulated flue gas conditions at 30℃ and normal pressure. Detailed Implementation

[0025] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] This embodiment prepares a CO2 adsorbent suitable for treating hot flue gas, and the preparation method is as follows: (1) Raw material pretreatment: 4-methylimidazole (4MI), 3-aminopropanol (3AP) and monoethanolamine (MEA) were placed in a vacuum drying oven and vacuum dried at 60°C for 24 hours to remove moisture and volatile impurities, and then set aside for use. (2) Preparation of binary DES: Weigh 0.05 mol 4MI and 0.15 mol 3AP, add them to a three-necked flask, and stir at 300 r / min for 2.5 h at 80 °C to obtain a uniform and transparent 4MI:3AP (1:3) binary DES; (3) Preparation of ternary DES: Add 20wt% MEA to the above binary DES and continue stirring at 300r / min at room temperature for 1.5h to obtain a uniform and transparent 4MI:3AP(1:3)+20wt%MEA ternary DES, which is the CO2 adsorbent.

[0028] Example 2

[0029] In this embodiment, the MEA content in Example 1 is increased to 30% of the mass of binary DES.

[0030] Example 3

[0031] In this embodiment, the MEA content in Example 1 is increased to 40% of the mass of the binary DES.

[0032] Comparative Example 1 This comparative example does not include MEA.

[0033] Comparative Example 2 In this comparative example, the amount of MEA added was 10 wt% of the mass of the binary DES.

[0034] Comparative Example 3 In this comparative example, the amount of MEA added was 50 wt% of the mass of the binary DES.

[0035] Comparative Example 4 This comparative example does not contain MEA, and the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:1.

[0036] Comparative Example 5 This comparative example does not contain MEA, and the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:2.

[0037] Comparative Example 6 This comparative example does not contain MEA, and the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:4.

[0038] Comparative Example 7 This comparative example does not contain MEA, and the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:5.

[0039] Comparative Example 8 In this comparative example, MEA in Example 1 is replaced with an equal amount of EG.

[0040] Comparative Example 9 In this comparative example, MEA in Example 1 was replaced with an equal amount of 2-NH2Py.

[0041] Comparative Example 10 This comparative example does not contain MEA, and 4-methylimidazole (4MI) is replaced with imidazole IM.

[0042] Comparative Example 11 This comparative example does not contain MEA, and 4-methylimidazole (4MI) is replaced with 1,2-dimethylimidazole 2DMI.

[0043] The absorption performance of the above eutectic solvents for CO2 was measured at 30℃ and normal pressure. The results are shown in Table 1.

[0044] Table 1:

[0045] As can be seen from the above examples and comparative examples, when the molar ratio of hydrogen bond acceptor to hydrogen bond donor is determined to be 1:3, the eutectic solvent composed of 4-methylimidazole (4MI) and 3-aminopropanol (3AP) has a better CO2 absorption capacity than the eutectic solvent composed of imidazole IM / 1,2-dimethylimidazole 2DMI and 3AP; among the five ratios of 4MI to 3AP (1:1, 1:2, 1:3, 1:4, 1:5), the molar ratio of 4-methylimidazole (4MI) to 3-aminopropanol (3AP) is 1:3, which has a better CO2 absorption capacity. In ternary DES, when MEA, EG, and 2-NH₂Py are added respectively, the eutectic solvent obtained by adding MEA in a 4MI:3AP eutectic solvent exhibits a superior CO₂ absorption capacity. When MEA is added at a concentration of 20-40 wt%, the resulting eutectic solvent shows a superior CO₂ absorption capacity compared to those with 0%, 10%, or 50% MEA. Furthermore, experiments revealed that when the second hydrogen bond acceptor is EG or 2-NH₂Py, and their addition constitutes 10-50% of the binary DES (4MI:3AP=1:3) mass, the CO₂ absorption capacity of the resulting ternary DES significantly decreases compared to the binary DES. Only when the second hydrogen bond acceptor is MEA does the resulting eutectic solvent exhibit a positive change in CO₂ absorption capacity.

[0046] The following tests were conducted on the ternary DES obtained in Example 1, including viscosity as a function of temperature, CO2 adsorption capacity as a function of temperature, water resistance, thermal stability, and cycling performance.

[0047] 1. Viscosity as a function of temperature test Viscosity is a crucial parameter for DES in industrial applications. Under normal pressure and different temperatures, the viscosity changes of four eutectic solvents—Example 1 (DES+MEA), Comparative Example 1 (DES), Comparative Example 8 (DES+EG), and Comparative Example 9 (DES+2AP)—as a function of temperature were measured. Figure 1 As shown. By Figure 1 It is known that the viscosity of the ternary DES in Example 1 is always lowest between 25°C and 45°C, which helps the diffusion rate and mass transfer efficiency of CO2. As the temperature increases, the viscosity of the ternary DES system of the present invention decreases significantly. This not only improves its liquid phase fluidity, enhances CO2 gas-liquid contact and mass transfer efficiency, and promotes the absorption of CO2 by the ternary DES, but also helps to overcome the energy barrier in the reaction process of CO2 with basic sites (such as amino groups), promotes the formation of products such as carbamates, and thus increases the CO2 capture capacity per unit mass of absorbent.

[0048] 2. Test on the change of CO2 adsorption capacity with temperature In the CO2 absorption experiment of DES, the absorption temperature is a key factor that directly determines the decarbonization efficiency of DES. The changes in CO2 absorption performance of 4MI:3AP (1:3) DES + 20% MEA at different temperatures were tested, and the experimental results are as follows: Figure 2 As shown. Figure 2 As shown, with the increase of experimental temperature, the absorption capacity of CO2 by 4MI:3AP (1:3) DES+20% MEA gradually increases. When the temperature increases from 20℃ to 100℃, the absorption capacity of DES increases from 0.1533gCO2 / gDES to 0.2172gCO2 / gDES (an increase of 41.7%), indicating that high temperature is beneficial to the absorption of CO2 by DES.

[0049] 3. Water resistance test Industrial flue gas often contains about 10% moisture, and the 4MI:3AP(1:3)+20% MEA solution comes into contact with moisture in the air during experimental preparation and use. Therefore, the effect of the small amount of moisture in the DES on CO2 absorption performance needs to be considered. This experiment studied the changes in CO2 absorption capacity of 4MI:3AP(1:3)+20% MEA for CO2 capture of flue gas with moisture contents of 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% under 30℃ and normal pressure conditions. Figure 3 .

[0050] Depend on Figure 3 It is known that moisture has an adverse effect on the CO2 absorption performance of DES. However, the moisture content of industrial flue gas usually does not exceed 20%. When 4MI:3AP (1:3)+20% MEA DES comes into contact with flue gas containing 10wt% moisture, its CO2 absorption capacity decreases from 0.18g CO2 / g DES to 0.1742g CO2 / g DES, a decrease of approximately 0.03%. The experimental results show that a small amount of moisture in the flue gas has a relatively small impact on the decarbonization performance of 4MI:3AP (1:3)+20% MEA DES, and this DES can be stably applied in flue gas environments.

[0051] 4. Thermal stability analysis Thermal stability is an important parameter of DES. The higher the thermal decomposition temperature of 4MI:3AP(1:3)+20% MEA DES, the better its thermal stability, which is more conducive to its stable existence at high temperatures and maintaining its good CO2 absorption-desorption performance. Under N2 protection, the mass change of 4MI:3AP(1:3)+20% MEA DES was observed as the temperature was increased from room temperature to 500℃ at a rate of 10℃ / min, and the TGA curve of 4MI:3AP(1:3)+20% MEA DES was plotted. Figure 4 As shown, the initial decomposition temperature of 4MI:3AP(1:3)+20% MEA DES is 93℃, and it completely decomposes at 220℃, exhibiting good thermal stability. Furthermore, the decomposition temperature of 4MI:3AP(1:3)+20% MEA DES is much higher than the desorption temperature (90℃) in the experiment, ensuring its structural integrity and preventing solvent loss during desorption, allowing for subsequent DES cycle performance testing. The desorption process not only requires reaching the desorption temperature but also requires continuous nitrogen gas flow to desorb carbon dioxide.

[0052] 5. Cyclic performance The regeneration and recycling performance of DES directly affects its cost in industrial applications. The recycling performance of 4MI:3AP(1:3)+20% MEA DES was investigated, and the experimental results are as follows: Figure 5As shown in the figure, CO2 absorption experiments were conducted at 30℃ and normal pressure, and desorption experiments were conducted at 90℃. A five-cycle absorption-desorption experiment was performed on CO2. The results showed that after five absorption-desorption cycles, the CO2 absorption capacity of 4MI:3AP(1:3) + 20%MEA DES remained stable at approximately 0.1683 g CO2 / g DES, while exhibiting a high desorption rate of over 90% (90.8% desorption rate in the 5th cycle). This system exhibits highly reversible cyclic characteristics in the CO2 absorption-desorption process, and its performance stabilized after five cycles. This excellent regeneration performance can reduce the industrial regeneration cost of DES and expand its application.

[0053] The CO2 absorption capacity, temperature-dependent CO2 absorption capacity, and water resistance of the ternary DES of this invention were tested under simulated flue gas conditions. The simulated flue gas composition was 15% CO2 by volume + 85% N2 by volume. This ratio closely matches the typical CO2 content range of industrial flue gas (such as flue gas from coal-fired or gas-fired boilers) (usually 10%-18%), and is a commonly used simulated flue gas system in the field of carbon capture. The effect of moisture in the flue gas was also investigated in the experiment: operating conditions with moisture contents of 10wt%, 30wt%, and 50wt%, covering the actual moisture range of industrial flue gas (usually 5%~20%).

[0054] 1. CO2 absorption capacity of ternary DES under simulated flue gas conditions The CO2 absorption performance of 4MI-3AP:MEA DESs with different proportions was tested under simulated flue gas conditions at 30℃ and normal pressure. The CO2 absorption capacity of five different mass ratios of eutectic solvents is as follows: Figure 6 As shown, at 30°C, the CO2 absorption capacities of five different mass ratios of 4MI-3AP DESs were 0.1155 (Comparative Example 2), 0.1417 (Example 1), 0.1381 (Example 2), 0.1344 (Example 3), and 0.134 g CO2 / g DES (Comparative Example 3), respectively. It can be seen that with increasing MEA content, the CO2 absorption capacity of DESs first increases and then decreases, with the highest CO2 absorption capacity observed under flue gas conditions when the ratio was 10:2 (MEA addition was 20 wt% of the binary DES mass).

[0055] 2. Effect of temperature on CO2 absorption capacity of ternary DES under simulated flue gas conditions In the CO2 absorption experiment of DES, the absorption temperature is a key factor that directly determines the decarbonization efficiency of DES. This experiment investigated the changes in the CO2 absorption performance of 4MI:3AP(1:3) DES+20% MEA in simulated flue gas under different temperature conditions. The experimental results are as follows: Figure 7As shown, with the increase of experimental temperature, the CO2 absorption capacity of 4MI:3AP(1:3)DES+20% MEA gradually increased. When the temperature increased from 20℃ to 100℃, the absorption capacity of DES increased from 0.1333g CO2 / gDES to 0.1872g CO2 / gDES (an increase of 40.4%), indicating that high temperature is more conducive to the absorption of CO2 by DES. This makes the ternary DES of the present invention very suitable for capturing CO2 in hot flue gas at high temperature and ambient temperature.

[0056] 3. Effect of Moisture Content on CO2 Absorption Capacity of Ternary DES under Simulated Flue Gas Conditions Because the flue gas contains approximately 10% moisture, and the 4MI:3AP(1:3)+20% MEA solution comes into contact with moisture in the air during experimental preparation and use, the impact of the small amount of moisture in the DES on CO2 absorption performance needs to be considered. This experiment investigated the CO2 absorption capacity of 4MI:3AP(1:3)+20% MEA on flue gas with moisture contents of 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% under simulated flue gas conditions at 30℃ and normal pressure. Figure 8 As shown.

[0057] Depend on Figure 8 It is known that moisture has an adverse effect on the CO2 absorption performance of DES. However, after 4MI:3AP (1:3) + 20% MEA came into contact with flue gas containing 10wt% moisture, its CO2 absorption capacity decreased from 0.1417 gCO2 / gDES to 0.14 gCO2 / gDES, a decrease of approximately 0.01%. The experimental results indicate that a small amount of moisture in the flue gas has a relatively small impact on the decarbonization performance of 4MI:3AP (1:3) + 20% MEA DES, and this DES can be stably applied in flue gas environments.

[0058] Furthermore, the DES prepared by this invention exhibits a CO2 / N2 selectivity of approximately 98, demonstrating good selective separation performance for CO2.

[0059] Furthermore, the performance of the ternary DES (4MI:3AP+20wt%MEA) of the present invention is compared with that of other DES in Table 2.

[0060] Table 2:

[0061] As shown in the table above, the CO2 absorption capacity of existing DES adsorbents decreases to varying degrees with increasing temperature. Among them, the decrease is more than 50% for aromatic amine-polyol and superalkali functionalized DES, which cannot be adapted to medium- and high-temperature industrial hot flue gas scenarios. However, the adsorbent of this invention with a MEA content of 20-40 wt% shows a significant increase in absorption capacity with increasing temperature in the range of 20~100℃, which is in stark contrast to the existing DES system. It is a novel DES adsorbent suitable for CO2 capture in medium- and high-temperature hot flue gas.

[0062] In summary, the ternary eutectic solvent adsorbent 4MI:3AP(1:3) + 20-40wt%MEA prepared by this invention solves the technical problem of absorption capacity decay at high temperatures in existing DES adsorbents, achieving efficient capture of CO2 in industrial hot flue gas at 20~100℃. Furthermore, it exhibits wide adaptability to MEA ratios, good water resistance, excellent thermal stability and cycling performance, and a simple preparation process with controllable cost, making it highly valuable for industrial applications. The adsorbent with a MEA mass ratio of 20wt% shows the best overall performance and is the preferred embodiment.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions, or combinations of technical features in the above embodiments that do not conflict with each other, can be made in accordance with the manner described in the embodiments. These modifications, substitutions or combinations do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A CO2 adsorbent suitable for treating hot flue gas, characterized in that, The adsorbent is a ternary eutectic solvent with 4-methylimidazole 4MI as the first hydrogen bond acceptor, 3-aminopropanol 3AP as the hydrogen bond donor, and monoethanolamine MEA as the second hydrogen bond acceptor. The molar ratio of 4MI to 3AP is 1:3, and the mass of monoethanolamine MEA accounts for 20-40 wt% of the mass of the binary eutectic solvent composed of 4MI and 3AP.

2. A method for preparing a CO2 adsorbent suitable for treating hot flue gas, characterized in that, Includes the following steps: S1. Raw material pretreatment: Place 4-methylimidazole, 3-aminopropanol and monoethanolamine in a vacuum drying oven and vacuum dry at 40-60℃ for 20-24h to remove moisture and volatile impurities from the raw materials for later use. S2. Preparation of binary eutectic solvent: Weigh pretreated 4-methylimidazolium (4MI) and 3-aminopropanol (3AP) in a molar ratio of 1:3, add them to a container with a stirrer, and stir at 70-80℃ for 1.5-3 hours until a homogeneous, transparent, and stable liquid is formed to obtain the 4MI:3AP binary eutectic solvent. S3. Preparation of ternary eutectic solvent: Add 20-40 wt% of pretreated monoethanolamine MEA to the above 4MI:3AP binary eutectic solvent. Continue stirring at room temperature until a homogeneous, transparent, and stable liquid is formed, thus obtaining a CO2 adsorbent suitable for treating hot flue gas.

3. The application of the CO2 adsorbent according to claim 1 in capturing CO2 in hot flue gas.

4. The application according to claim 3, characterized in that, The temperature of the hot flue gas is 20-100℃.

5. A method for capturing CO2 in hot flue gas, characterized in that, This includes capturing CO2 from industrial hot flue gas at 20-100°C and normal pressure using the aforementioned CO2 adsorbent.

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