Azacyclo ionic liquid solvent as well as preparation method and application thereof

Abstract

The invention provides an azacyclo-ionic liquid solvent as well as a preparation method and application thereof. The azacyclo-ionic liquid solvent comprises azacyclo-ionic liquid and an organic solvent, the structure of the azacyclo ionic liquid is [M] [Y], [M] is an imidazole cation, and [Y] is an azacyclo anion and comprises any one of [Y1], [Y2], [Y3] or [Y4]. The azacyclo ionic liquid solvent provided by the invention realizes directional regulation and control on the phase change behavior of the solvent after CO2 is absorbed by regulating the structures and polarities of the imidazole cations and the organic solvent, so that homogeneous-phase or phase-change ionic liquid solvents meeting different requirements are obtained, and absorbents adaptive to different scenes are obtained; guidance is provided for directional design of the carbon capture functional ionic liquid solvent, and the workload in solvent design is effectively reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas separation and purification, and particularly relates to a nitrogen heterocyclic ionic liquid solvent and a preparation method and application thereof. BACKGROUND

[0002] The exploitation and use amount of fossil fuels such as petroleum and coal increase year by year, resulting in a large amount of CO2 emission, causing serious climate and environmental problems such as global warming and ocean acidification. How to reduce CO2 emission has become a great challenge facing the world. The chemical absorption method represented by alcohol amine solution is the most widely used carbon capture technology at present, but it has problems such as high water content, high regeneration energy consumption and high solvent loss. In recent years, phase change absorbents have become one of the research hotspots for realizing low-energy consumption CO2 capture due to their unique phase separation performance. In the regeneration process, only the CO2-rich phase needs to be desorbed, which can greatly reduce the regeneration volume of the absorbent and in turn reduce the regeneration energy consumption. Wang et al. (Fuel, 2022, 325, 124885) studied the phase change behavior of amine / 1-propanol / H2O absorbent. The absorbent composed of 30wt.%TETA and 50wt.%1-propanol rapidly separates into two phases in 2 minutes at 60℃, the CO2 capacity of the rich phase is as high as 6.06mol / L, the volume ratio is 38.9%, and the regeneration energy consumption is 2.06GJ / t CO2, which is 48.4% lower than that of 30wt.%MEA.

[0003] Recent studies have reported several methods to correlate the phase transition behavior with the composition of the solvent system. Machida et al. (Int. J. Greenh. Gas Control, 2018, 75, 1) studied three types of absorbents consisting of amines, water, and ethers (phase separation, miscible, and insoluble), and pointed out that different phase behaviors are determined by the combination of amines and ethers. Subsequently, Yang et al. (Sep. Purif. Technol, 2025, 358, 130318) studied the phase separation behavior of 5.0 M mixed amines and verified this conclusion: when the molecular polarity index (MPI) of tertiary amines is less than 6.74 kcal / mol, the absorbent remains in a homogeneous state before and after absorbing CO2; when 9.00 kcal / mol < MPI < 10.08 kcal / mol, the homogeneous absorbent undergoes phase separation after absorbing CO2, indicating that the difference in polarity between components is the key factor that triggers phase separation. Zhao et al. (Chem. Eng. J, 2021, 422, 130389) used density functional theory and statistical models to obtain the ionic log P of the product, predicting the phase separation behavior of amine / organic solvent / water systems during the CO2 absorption process, and proposed a boundary line between the two-phase and single-phase systems based on the log P of anions and cations. Shen et al. (Sep. Purif. Technol., 2022, 300, 121908) studied the phase transition behavior of 30 non-aqueous alkanolamine and ethylene glycol ether combination systems before and after absorbing CO2, and proposed a solubility parameter interaction distance (SPID) parameter (i.e., SPID = 19.5) that better predicts the two-phase and single-phase behavior of the system. Although there have been reports on the phase transition behavior of amine-water systems, these systems with phase transition behavior still rely heavily on extensive experimental screening, and the model parameters cannot well predict the influence of related components, and the research conclusions are limited to the types of organic amines and solvents explored and lack of universality; at the same time, organic amine phase transition absorbents still face the problems of solvent loss and high energy consumption in regeneration due to the presence of volatile water and organic amines.

[0004] Ionic liquids have no vaporization heat and low specific heat capacity, which can reduce the latent heat of regeneration. More importantly, the combination of different structures of anions and cations, specific structural design can directional regulate the acidity and basicity, polarity of ionic liquids and the hydrogen bond, chemical interaction between ionic liquids and gas, and realize the efficient and selective separation of gas. Sun et al. (Ind. Eng. Chem. Res., 2024, 63, 9515-9526) developed a [N 2222[1,2,4-Triz] and N-MI constitute anhydrous two-phase absorbent, the absorption capacity can reach 0.119g CO2 / g solvent, wherein the CO2 absorption capacity in the CO2-rich phase accounts for 95% of the total capacity, and the volume only accounts for 60% of the total volume of the system, and the regeneration energy consumption is reduced to 1.29GJ / t CO2, and the absorbent still has good absorption performance after 5 cycles. At present, various homogeneous and phase change ionic liquid absorbents with excellent absorption-desorption performance have been reported, but there is no research on how to directionally regulate the phase change behavior of the solvent after absorbing CO2. Therefore, how to provide a method capable of effectively directionally regulating the phase change behavior of the solvent after absorbing CO2, so as to obtain homogeneous or phase change ionic liquid solvents meeting different requirements, has become a problem to be solved. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a nitrogen heterocyclic ionic liquid solvent and a preparation method and application thereof. The nitrogen heterocyclic ionic liquid solvent provided by the present application realizes directional regulation of the phase change behavior of the solvent after absorbing CO2 by adjusting the structure and polarity of the imidazole cation and the organic solvent, thereby obtaining homogeneous or phase change ionic liquid solvents meeting different requirements, obtaining absorbents adapted to different scenarios, providing guidance for the directional design of carbon capture functional ionic liquid solvents, and effectively reducing the workload in solvent design.

[0006] To achieve the purpose of the present application, the following technical solutions are adopted:

[0007] In a first aspect, the present application provides a nitrogen heterocyclic ionic liquid solvent, which comprises a nitrogen heterocyclic ionic liquid and an organic solvent.

[0008] The structure of the nitrogen heterocyclic ionic liquid is [M][Y], wherein [M] is an imidazole cation, and [Y] is a nitrogen heterocyclic anion, including any one of [Y1], [Y2], [Y3] or [Y4].

[0009] The structures of [M], [Y1], [Y2], [Y3] and [Y4] are as follows:

[0010]

[0011] Among them, R1, R2, R3 are independently selected from H, C n H 2n+1 or C n H 2n OH, K1, K2, K3 are independently selected from H, NH2, C n H 2n+1 , C n H 2n OH or CN.

[0012] n is an integer from 1 to 6 (1, 2, 3, 4, 5, or 6).

[0013] The above-mentioned specific component, structure of the nitrogen heterocyclic ionic liquid solvent can be achieved by adjusting the structure and polarity of imidazole cation and organic solvent to realize the directional regulation of the solvent phase behavior after absorbing CO2, thereby obtaining a homogeneous or phase change ionic liquid solvent that meets different needs, obtaining an absorbent that adapts to different scenarios, providing guidance for the directional design of carbon capture functional ionic liquid solvent, and effectively reducing the workload in solvent design.

[0014] Preferably, the organic solvent includes any one or a combination of at least two of sulfolane, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monobutyl ether, or triethylene glycol dimethyl ether.

[0015] Preferably, in the nitrogen heterocyclic ionic liquid solvent, the mass fraction of the nitrogen heterocyclic ionic liquid is 20-90%, for example, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%, etc., but not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.

[0016] Preferably, the absorption temperature of the nitrogen heterocyclic ionic liquid solvent for CO2 is 30-60℃, for example, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, or 60℃, etc., but not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.

[0017] Preferably, the desorption temperature of the nitrogen heterocyclic ionic liquid solvent is 80-100℃, and the desorption pressure is 0.01-1bar, wherein the desorption temperature can be 80℃, 85℃, 90℃, 95℃, or 100℃, etc., and the desorption pressure can be 0.01bar, 0.05bar, 0.1bar, 0.2bar, 0.3bar, 0.4bar, 0.5bar, 0.6bar, 0.7bar, 0.8bar, 0.9bar, or 1bar, etc., but not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.

[0018] Preferably, the nitrogen heterocyclic ionic liquid solvent is homogeneous before absorbing CO2 and presents a homogeneous phase, a liquid-liquid two-phase, or a liquid-solid two-phase after absorbing CO2, wherein the volume of the CO2-rich phase in the nitrogen heterocyclic ionic liquid solvent after phase change accounts for 10-60% of the total volume of the nitrogen heterocyclic ionic liquid solvent.

[0019] In a second aspect, the present application provides a preparation method of the nitrogen heterocyclic ionic liquid solvent as described above, which comprises the following steps:

[0020] The imidazole compound and the nitrogen heterocyclic compound are mixed to obtain a nitrogen heterocyclic ionic liquid, and then mixed with an organic solvent to obtain the nitrogen heterocyclic ionic liquid solvent.

[0021] In a third aspect, the application further provides application of the nitrogen heterocyclic ionic liquid solvent as described above in CO2 capture separation.

[0022] Compared with the prior art, the application has the following beneficial effects:

[0023] The application provides a nitrogen heterocyclic ionic liquid solvent (binary anhydrous system), which can realize directional regulation of phase change behavior of the solvent after the product absorbs CO2 by adjusting the structure and polarity of the imidazole cation and the organic solvent, thereby obtaining a homogeneous or phase change ionic liquid solvent meeting different requirements, obtaining an absorbent suitable for different scenes, providing guidance for directional design of a carbon capture functional ionic liquid solvent, effectively reducing the workload in solvent design, and effectively guiding relevant personnel to obtain a homogeneous and phase change ionic liquid absorbent meeting different application requirements, and the application is suitable for CO2 capture separation of various gas sources such as flue gas of a thermal power plant, chemical tail gas, and coal bed gas. DETAILED DESCRIPTION

[0024] In order to further illustrate the technical means adopted by the application and the effects thereof, the technical solution of the application will be further described below in combination with preferred embodiments of the application, but the application is not limited in the scope of the embodiments.

[0025] Embodiment 1

[0026] This embodiment provides three kinds of nitrogen heterocyclic ionic liquids, and the preparation method is as follows:

[0027] 1) 0.2 mol of sodium 1,2,4-triazolate is added to a 250 mL round-bottom flask containing 100 mL of anhydrous ethanol, and stirred at room temperature until it is completely dissolved; at the same time, 0.2 mol of 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) is weighed in a 150 mL beaker, 100 mL of anhydrous ethanol is added to completely dissolve it, and then it is slowly added dropwise into the round-bottom flask, and stirred at room temperature for 48 h. After the reaction is completed, the solid NaCl is removed by filtration, and the ethanol is removed by rotary evaporation at 65 DEG C to obtain a light yellow turbid liquid, which is washed with anhydrous ethanol for multiple times, filtered, and rotary evaporated to obtain a light yellow transparent liquid, which is vacuum dried at 60 DEG C for 48 h to obtain the nitrogen heterocyclic ionic liquid [Emim][Triz], and the water content is less than 2000 ppm.

[0028] 2) In a 250 mL round bottom flask containing 100 mL of absolute ethanol, 0.2 mol of sodium 1,2,4-triazolate was added and stirred at room temperature until it was completely dissolved; meanwhile, 0.2 mol of 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HO-Emim]Cl) was weighed in a 150 mL beaker, 100 mL of absolute ethanol was added to make it completely dissolved, and then it was slowly added dropwise into the round bottom flask, and stirred at room temperature for 48 h. After the reaction was completed, the solid NaCl was removed by filtration, and the ethanol was removed by rotary evaporation at 65°C to obtain a yellow turbid liquid, which was washed with absolute ethanol several times, filtered, and rotary evaporated to obtain a yellow transparent liquid, which was vacuum dried at 60°C for 48 h to obtain the nitrogen heterocyclic ionic liquid [HO-Emim][Triz], the water content of which was less than 2000 ppm.

[0029] 3) In a 250 mL round bottom flask containing 100 mL of absolute ethanol, 0.2 mol of sodium 1,2,4-triazolate was added and stirred at room temperature until it was completely dissolved; meanwhile, 0.2 mol of 1-ethyl-2,3-dimethylimidazolium chloride ([Emmim]Cl) was weighed in a 150 mL beaker, 100 mL of absolute ethanol was added to make it completely dissolved, and then it was slowly added dropwise into the round bottom flask, and stirred at room temperature for 48 h. After the reaction was completed, the solid NaCl was removed by filtration, and the ethanol was removed by rotary evaporation at 65°C to obtain a yellow turbid liquid, which was washed with absolute ethanol several times, filtered, and rotary evaporated to obtain a yellow transparent liquid, which was vacuum dried at 60°C for 48 h to obtain the nitrogen heterocyclic ionic liquid [Emmim][Triz], the water content of which was less than 2000 ppm.

[0030] Example 2

[0031] 1) The [Emim][Triz] synthesized in (1) of Example 1 was mixed with ethylene glycol monoethyl ether (EGEE) at a mass ratio of 7:3 and stirred at 60°C for 4 h to obtain a uniform transparent nitrogen heterocyclic ionic liquid solvent [Emim][Triz] / EGEE (mass ratio 7:3). Without changing other conditions, the organic solvent was adjusted to be tetramethylene sulfone (TMS), diethylene glycol monobutyl ether (DEBGE), and N,N-dimethylformamide (DMF) to obtain the nitrogen heterocyclic ionic absorbent [Emim][Triz] / TMS (mass ratio 7:3), [Emim][Triz] / DEBGE (mass ratio 7:3), and [Emim][Triz] / DMF (mass ratio 7:3).

[0032] 2) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emim][Triz] / EGEE (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emim][Triz] / EGEE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.119 g CO2 / g absorbent. The results are shown in Table 1.

[0033] 3) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emim][Triz] / TMS (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emim][Triz] / TMS (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.115 g CO2 / g absorbent. The results are shown in Table 1.

[0034] 4) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emim][Triz] / DEBGE (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emim][Triz] / DEBGE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.131 g CO2 / g absorbent. The results are shown in Table 1.

[0035] 5) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emim][Triz] / DMF (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emim][Triz] / DMF (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.108 g CO2 / g absorbent. The results are shown in Table 1.

[0036] Example 3

[0037] 1) The [HO-Emim][Triz] synthesized in (2) of Example 1 was mixed with ethylene glycol monoethyl ether (EGEE) in a mass ratio of 7:3 and stirred at 60°C for 4h to obtain a homogeneous and transparent ionic liquid solvent [HO-Emim][Triz] / EGEE (mass ratio 7:3). Under other conditions unchanged, adjusting the organic solvent to be tetramethylene sulfone (TMS), diethylene glycol monobutyl ether (DEBGE) and N,N-dimethylformamide (DMF), the ionic liquid absorbents [HO-Emim][Triz] / TMS (mass ratio 7:3), [HO-Emim][Triz] / DEBGE (mass ratio 7:3), [HO-Emim][Triz] / DMF (mass ratio 7:3) were obtained.

[0038] 2) The absorption capacity of the ionic liquid solvent [HO-Emim][Triz] / EGEE (mass ratio 7:3) for CO2 was determined by weighing method. In the absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [HO-Emim][Triz] / EGEE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until no change was observed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.100 g CO2 / g absorbent. The results are shown in Table 1.

[0039] 3) The absorption capacity of the ionic liquid solvent [HO-Emim][Triz] / TMS (mass ratio 7:3) for CO2 was determined by weighing method. In the absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [HO-Emim][Triz] / TMS (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until no change was observed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.133 g CO2 / g absorbent. The results are shown in Table 1.

[0040] 4) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [HO-Emim][Triz] / DEBGE (mass ratio 7:3) for CO2 was determined by gravimetric method. In the absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [HO-Emim][Triz] / DEBGE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was measured at intervals until no change was observed. The phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.139 g CO2 / g absorbent. The results are shown in Table 1.

[0041] 5) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [HO-Emim][Triz] / DMF (mass ratio 7:3) for CO2 was determined by gravimetric method. In the absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [HO-Emim][Triz] / DMF (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was measured at intervals until no change was observed. The phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.112 g CO2 / g absorbent. The results are shown in Table 1.

[0042] Example 4

[0043] 1) The [Emmim][Triz] synthesized in (3) of Example 1 was mixed with ethylene glycol monoethyl ether (EGEE) at a mass ratio of 7:3 and stirred at 60°C for 4 h to obtain a uniform transparent nitrogen heterocyclic ionic liquid solvent [Emmim][Triz] / EGEE (mass ratio 7:3). By adjusting the organic solvent to be sulfolane (TMS), diethylene glycol monobutyl ether (DEBGE), and N,N-dimethylformamide (DMF) under the same conditions, the nitrogen heterocyclic ionic absorbents [Emmim][Triz] / TMS (mass ratio 7:3), [Emmim][Triz] / DEBGE (mass ratio 7:3), and [Emmim][Triz] / DMF (mass ratio 7:3) were obtained.

[0044] 2) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emmim][Triz] / EGEE (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emmim][Triz] / EGEE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.140 g CO2 / g absorbent. The results are shown in Table 1.

[0045] 3) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emmim][Triz] / TMS (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emmim][Triz] / TMS (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.134 g CO2 / g absorbent. The results are shown in Table 1.

[0046] 4) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emmim][Triz] / DEBGE (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emmim][Triz] / DEBGE (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.156 g CO2 / g absorbent. The results are shown in Table 1.

[0047] 5) The absorption capacity of the nitrogen heterocyclic ionic liquid solvent [Emmim][Triz] / DMF (mass ratio 7:3) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emmim][Triz] / DMF (mass ratio 7:3) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was taken at intervals until the weight no longer changed, the phase change of the absorbent was observed, and the absorption capacity of the absorbent for CO2 was calculated to be 0.115 g CO2 / g absorbent. The results are shown in Table 1.

[0048] Example 5

[0049] 1) The [Emmim][Triz] synthesized in (3) of Example 1 was mixed with ethylene glycol monoethyl ether (EGEE) at a mass ratio of 6:4 and stirred at 60°C for 4h to obtain a uniform transparent azacyclic ionic liquid solvent [Emmim][Triz] / EGEE (mass ratio 6:4).

[0050] 2) The absorption capacity of the azacyclic ionic liquid solvent [Emmim][Triz] / EGEE (mass ratio 6:4) for CO2 was determined by the weighing method. In an absorption bottle with an inner diameter of 2.00 cm, 3.00 g of [Emmim][Triz] / EGEE (mass ratio 6:4) was added, and after a period of stabilization, CO2 was introduced at a flow rate of 100 mL / min, a temperature of 40°C, and a pressure of 1 bar. The weight of the absorption bottle was measured at intervals until no further change was observed, and the phase change of the absorbent was observed. The absorption capacity of the absorbent for CO2 was calculated to be 0.110 g CO2 / g absorbent, as shown in Table 1.

[0051] Table 1 Solvent state and absorption capacity of azacyclic ionic liquid solvents in Examples 2-5 after absorbing CO2

[0052]

[0053] From the above data, it can be found that by adjusting the structure and polarity of the imidazolium cation and the organic solvent, the phase change behavior of the product after absorbing CO2 can be directionally controlled. The three imidazolium cations have different structures (such as -OH and -CH3), resulting in different polarities. When combined with solvents of various polarities, the difference in polarity causes the resulting ionic liquid solvent to exhibit single-phase, partial two-phase, and full two-phase states after absorbing CO2, achieving directional control of the phase change behavior. This allows the product to meet different needs and adapt to different scenarios, providing guidance for the directional design of carbon capture functional ionic liquid solvents and effectively reducing the workload in solvent design.

[0054] The applicant declares that the azacyclic ionic liquid solvent of the present application, its preparation method and application are illustrated by the above examples, but the present application is not limited to the above examples, i.e. it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the scope of protection and disclosure of the present application.

[0055] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0056] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, various possible combinations are not described again by the present application.

Claims

1. A nitrogen heterocyclic ionic liquid solvent, characterized by, The nitrogen heterocyclic ionic liquid solvent comprises a nitrogen heterocyclic ionic liquid and an organic solvent. The nitrogen heterocyclic ionic liquid has a structure of [M][Y], wherein [M] is an imidazole cation, and [Y] is a nitrogen heterocyclic anion, including any one of [Y1], [Y2], [Y3] or [Y4]. The structures of [M], [Y1], [Y2], [Y3] and [Y4] are shown as follows: wherein R1, R2, R3are independently selected from H, C n H 2n+1 or C n H 2n OH, K1, K2, K3are independently selected from H, NH2, C n H 2n+1 , C n H 2n OH or CN; n is an integer of 1-6.

2. The azaheterocyclic ionic liquid solvent according to claim 1, wherein The organic solvent includes any one or a combination of at least two of sulfolane, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monobutyl ether or triethylene glycol dimethyl ether.

3. The azacyclic ionic liquid solvent according to claim 1 or 2, wherein In the nitrogen heterocyclic ionic liquid solvent, the mass fraction of the nitrogen heterocyclic ionic liquid is 20-90%.

4. The azaheterocyclic ionic liquid solvent according to any one of claims 1 to 3, characterized in that, The absorption temperature of the nitrogen heterocyclic ionic liquid solvent for CO2 is 30-60℃.

5. The azaheterocyclic ionic liquid solvent according to any one of claims 1 to 4, wherein The desorption temperature of the nitrogen heterocyclic ionic liquid solvent is 80-100℃, and the desorption pressure is 0.01-1 bar.

6. The azacyclic ionic liquid solvent according to any one of claims 1 to 5, wherein, The nitrogen heterocyclic ionic liquid solvent is homogeneous before absorbing CO2, and presents a homogeneous phase, a liquid-liquid two-phase or a liquid-solid two-phase after absorbing CO2, wherein the volume of the CO2-rich phase in the nitrogen heterocyclic ionic liquid solvent after phase transition accounts for 10-60% of the total volume of the nitrogen heterocyclic ionic liquid solvent.

7. A process for the preparation of the ionic liquid solvent according to any one of claims 1 to 6, characterized in that, The preparation method comprises the following steps: The imidazole compound and the nitrogen heterocyclic compound are mixed to obtain a nitrogen heterocyclic ionic liquid, which is then mixed with the organic solvent to obtain the nitrogen heterocyclic ionic liquid solvent.

8. Use of the nitrogen heterocyclic ionic liquid solvent according to any one of claims 1-6 in CO2 capture separation.

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