Two-phase absorbent for CO2 capture and preparation method of two-phase absorbent

Abstract

The invention discloses a two-phase absorbent for capturing CO2, which is characterized by being prepared from the following components in percentage by mass: 25%-30% of N-(2-ethoxyl) ethylenediamine, 0%-3% of N-aminoethyl piperazine, 0%-3% of 2-(1-ethoxyl) pyridine, 10%-13% of N, N '-diethyl ethylenediamine, 15%-20% of N, N'-diethylethylenediamine, 5%-10% of N, N '-diethylethylenediamine, 5%-10% of N, N'-diethylethylenediamine and the balance of water. The invention relates to a cleaning agent which is prepared from the following components in percentage by weight: 1 to 5 percent of N, N-diethylhydroxylamine, 1 to 5 percent of pentamethyldiethylenetriamine, 0 to 2 percent of tert-butylamine ethoxyethanol, 0 to 3 percent of 2-amino-2-methyl-propyl alcohol, 5 to 8 percent of sulfolane, 5 to 8 percent of dimethyl ether, 5 to 8 percent of p-xylene and 5 to 8 percent of n-butyl alcohol. The composition can be prepared by uniformly stirring the components. The preparation method is simple, and the prepared two-phase absorbent can improve the saturated absorption capacity, improve the desorption rate and optimize the performance of the phase change absorbent.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and particularly relates to a biphasic absorbent for CO2 capture and a preparation method thereof. Background Art

[0002] Under the severe situation of global climate change, carbon dioxide (CO2), as one of the main components of greenhouse gases, its excessive emission has had a significant impact on global warming, causing many environmental problems and attracting wide attention globally. From the perspective of environmental science, the emission of a large amount of CO2 has disrupted the carbon balance of the earth's ecosystem, leading to a series of serious consequences such as intensified greenhouse effect, rising sea levels, and frequent extreme climate events, having a profound negative impact on the earth's ecological environment. Facing the severe challenges brought by the excessive emission of CO2, countries have invested resources in researching and applying various CO2 capture technologies. Among them, the chemical absorption method has stood out and become the mainstream CO2 capture technology in the industrial field due to its scientificity, reliability, and efficiency demonstrated in aspects such as theoretical basis, experimental verification, and actual application effects. However, traditional absorbents (such as monoethanolamine, MEA) have many deficiencies, such as limited absorption capacity (0.8 - 1.0 mol / mol amine). Taking the phase change absorbent with the publication number CN115845363B as an example, its absorption capacity is only 0.40 mol / mol, which is still high, and the desorption rate is poor, making it difficult to meet the urgent need to improve the performance of phase change absorbents.

[0003] The defects of the existing technology mainly focus on aspects such as high reaction enthalpy change, low mass transfer efficiency, and poor cycle stability. Therefore, developing a new type of absorbent with a high absorption capacity (≥0.603 mol / mol amine), up to 1.10 mol / mol amine, a rich phase volume fraction of 42 - 65%, reducing the regeneration energy consumption; and good regeneration performance, with a maximum desorption efficiency of up to 90.8% is of great significance for promoting the sustainable development of CO2 capture technology. Summary of the Invention

[0004] The purpose of the present invention is to provide a biphasic absorbent for CO2 capture and a preparation method thereof. The preparation method is simple, and the prepared biphasic absorbent can improve the saturated absorption capacity.

[0005] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0006] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 25%-30% of N-(2-hydroxyethyl)ethylenediamine, 0%-3% of N-aminoethylpiperazine, 0%-3% of 2-(1-hydroxyethyl)pyridine, 10%-13% of N,N'-diethylethylenediamine, 15%-20% of N,N-diethylhydroxylamine, 1%-5% of pentamethyldiethylenetriamine, 0%-2% of tert-butylaminoethoxyethanol, 0%-3% of 2-amino-2-methyl-propanol, 5%-8% of sulfolane, 5%-8% of dimethyl ether, 5%-8% of p-xylene, and 5%-8% of n-butanol; after the biphasic absorbent absorbs carbon dioxide, it is divided into a lean phase and a rich phase, and carbon dioxide is concentrated in the rich phase.

[0007] Preferably, the biphasic absorbent forms a biphasic system after saturated absorption of CO2 at 50°C, where the volume ratio of the rich phase is 42-65%, and the CO2 absorption capacity ≥ 0.603 mol / mol amine.

[0008] Preferably, the desorption efficiency of the absorbent is ≥ 39.9% at 130°C, and the highest desorption efficiency can reach 90.8%.

[0009] The present invention also provides a preparation method of the above-mentioned biphasic absorbent for CO2 capture. Weigh the above components according to the ratio and place them in a container, stir at 40-60°C for 15-30 minutes, and maintain the rotation speed at 200-400 rpm to form a homogeneous solution; then seal the container and perform ultrasonic dispersion treatment for 10-20 min to obtain the biphasic absorbent, and the ultrasonic power is 150-250 W.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] The present invention is composed of 8 amine compounds such as AEEA, AEP, and HEP (accounting for 45-60%) and organic solvents such as sulfolane and dimethyl ether (accounting for 25-35%); it achieves a breakthrough through the multi-amine gradient synergy and solvent regulation technology. Among them, 8 amine compounds construct a gradient reaction activity system, that is, the high reaction activity of primary amine AEEA, the piperazine ring of secondary amine AEP to enhance the cycle capacity, and pyridine-based HEP to enhance the basic sites, combined with sterically hindered amines PMDETA / AMP to reduce the reaction enthalpy. At the same time, the design of using sulfolane to enhance physical absorption, dimethyl ether to promote desorption, and n-butanol to regulate phase separation enables the absorbent to have a maximum saturated absorption capacity of 1.10 mol / mol amine at 50°C and a maximum desorption efficiency of 90.8%, which can significantly improve the capture efficiency and economy, and is applicable to coal-fired power plants, the steel industry, and chemical tail gas treatment, providing an efficient and low-cost solution for industrial flue gas CO2 capture. Description of the Drawings

[0012] Figure 1Effect diagram of the relationship between the absorption amount and absorption time of the biphasic absorbents prepared in Examples 1-10 of the present invention;

[0013] Figure 2 Effect diagram of the relationship between the absorption rate and absorption time of the biphasic absorbents prepared in Examples 1-10 of the present invention;

[0014] Figure 3 Effect diagram of the relationship between desorption and absorption time of the biphasic absorbents prepared in Examples 1-10 of the present invention;

[0015] Figure 4 Effect diagram of the relationship between the desorption rate and absorption time of the biphasic absorbents prepared in Examples 1-10 of the present invention;

[0016] Figure 5 Effect diagram of the phase ratio of the rich phase and lean phase of the biphasic absorbents prepared in Examples 1-10 of the present invention. Detailed implementation manners

[0017] The present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0018] Example 1

[0019] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 25% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 3% of N-aminoethylpiperazine (AEP), 3% of 2-(1-hydroxyethyl)pyridine (HEP), 13% of N,N'-diethylethylenediamine (DEEA), 15% of N,N-diethylhydroxylamine (DEHA), 5% of pentamethyldiethylenetriamine (PMDETA), 2% of tert-butylaminoethoxyethanol (TBEE), 2% of 2-amino-2-methyl-propanol (AMP), 8% of sulfolane, 8% of dimethyl ether, 8% of p-xylene, and 8% of n-butanol.

[0020] The preparation method is as follows: Weigh the above components according to the ratio and place them in a container, stir at 40-60 °C for 15-30 minutes; slowly add deionized water to the container and maintain the rotation speed at 200-400 rpm to form a homogeneous solution; then seal the container and perform ultrasonic dispersion treatment for 10-20 min to obtain the biphasic absorbent, and the ultrasonic power is 150-250 W.

[0021] Absorption experiment:

[0022] At 40 °C, the absorption performance of the CO2 absorbents prepared in Examples 1-10 was detected.

[0023] Desorption experiment:

[0024] At 130 °C, the desorption performance of the CO2 absorbents prepared in Examples 1-10 was detected respectively.

[0025] Experimental procedure: This process was carried out in a bubble absorption device. Stir for 15 - 30 minutes at 50 °C; maintain the rotation speed at 200 - 400 rpm. After forming a homogeneous solution, introduce high-purity CO2 gas at a flow rate of 200 mL / min until the solution is saturated with absorption, and then phase separation occurs. Monitor the gas flow difference through a mass flow meter and a wet gas meter, record the absorption time and the volume of the outgoing gas, and calculate the absorption capacity β1 = (V0t160 - V1) / (1000×22.4×(n_AEEA + n_DEEA + n_DEHA + n_PMDETA)). Subsequently, place the rich phase in an oil bath at a constant temperature of 130 °C for heating and desorption. Measure the CO2 release amount through a mass flow meter. The desorption efficiency is calculated as β2 / β1×100%, where β2 = V2 / (1000×22.4×(n_AEEA + n_DEEA + n_DEHA + n_PMDETA)).

[0026] During the absorption and desorption processes, record the absorption load and desorption load of the phase-change absorption solvent using the difference between the mass flow meter and the wet gas meter. Differentiate the relationship between the absorption load and time to obtain the relationship between the absorption rate of the solution and time; differentiate the relationship between the desorption load and time to obtain the relationship between the desorption rate of the solution and time.

[0027] Detection results: As Figure 5 shown, after the solution is saturated with absorption, liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 58.2 mL, and the volume of the lean phase is 49.9 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 1.02 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.0135 mol CO2 / mol / s. As Figure 3 shown, after the rich phase desorbs for 100 min, the desorption amount of the solution is 0.407 mol / mol, as Figure 4 shown, the initial desorption rate is 0.00689 mol CO2 / mol / s, and the desorption efficiency is 39.9%.

[0028] Example 2

[0029] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 30% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 13% of N,N'-diethylethylenediamine (DEEA), 20% of N,N-diethylhydroxylamine (DEHA), 5% of pentamethyldiethylenetriamine (PMDETA), 8% of sulfolane, 8% of dimethyl ether, 8% of p-xylene, and 8% of n-butanol.

[0030] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0031] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase transition occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 65.16 mL, and the volume of the lean phase is 35.54 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 1.102 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.0103 mol CO2 / mol / s. As Figure 3 shown, after the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.5952 mol / mol, as Figure 4 shown, the initial desorption rate is 0.00652 mol CO2 / mol / s, and the desorption efficiency is 54%.

[0032] Example 3

[0033] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 27% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 3% of N-aminoethylpiperazine (AEP), 3% of 2-(1-hydroxyethyl)pyridine (HEP), 13% of N,N'-diethylethylenediamine (DEEA), 17% of N,N-diethylhydroxylamine (DEHA), 5% of pentamethyldiethylenetriamine (PMDETA), 2% of tert-butylaminoethoxyethanol (TBEE), 2% of 2-amino-2-methyl-propanol (AMP), 7% of sulfolane, 7% of dimethyl ether, 7% of p-xylene, and 7% of n-butanol.

[0034] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0035] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase transition occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 55.7 mL, and the volume of the lean phase is 44.2 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.818 mol CO2 / mol,Figure 2 The absorption rate of the shown solution is 0.0118 mol CO2 / mol / s. As Figure 3 shown, the desorbed amount of the solution after 100 min of rich-phase desorption is 0.425 mol / mol. As Figure 4 shown, the initial desorption rate is 0.00348 mol CO2 / mol / s, and the desorption efficiency is 51.9%.

[0036] Example 4

[0037] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 28% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 2% of N-aminoethylpiperazine (AEP), 2% of 2-(1-hydroxyethyl)pyridine (HEP), 12% of N,N'-diethylethylenediamine (DEEA), 16% of N,N-diethylhydroxylamine (DEHA), 4% of pentamethyldiethylenetriamine (PMDETA), 1% of tert-butylaminoethoxyethanol (TBEE), 1% of 2-amino-2-methyl-propanol (AMP), 6% of sulfolane, 6% of dimethyl ether, 6% of p-xylene, and 6% of n-butanol.

[0038] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0039] Test results: As Figure 5 shown, after the solution is saturated in absorption, liquid-solid phase transition occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 58.3 mL, and the volume of the lean phase is 42.3 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.98 mol CO2 / mol. As Figure 2 shown, the absorption rate of the solution is 0.0135 mol CO2 / mol / s. As Figure 3 shown, the desorbed amount of the solution after 100 min of rich-phase desorption is 0.472 mol / mol. As Figure 4 shown, the initial desorption rate is 0.00352 mol CO2 / mol / s, and the desorption efficiency is 48.16%.

[0040] Example 5

[0041] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 26% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 1% of N-aminoethylpiperazine (AEP), 1% of 2-(1-hydroxyethyl)pyridine (HEP), 11% of N,N'-diethylethylenediamine (DEEA), 19% of N,N-diethylhydroxylamine (DEHA), 2% of pentamethyldiethylenetriamine (PMDETA), 5% of sulfolane, 5% of dimethyl ether, 5% of p-xylene, and 5% of n-butanol.

[0042] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0043] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 50.26 mL, and the volume of the lean phase is 50.84 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.9034 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.01135 mol CO2 / mol / s. As Figure 3 shown, after the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.365 mol / mol, as Figure 4 shown, the initial desorption rate is 0.00253 mol CO2 / mol / s, and the desorption efficiency is 40.4%.

[0044] Example 6

[0045] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 29% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 10% of N,N'-diethylethylenediamine (DEEA), 18% of N,N-diethylhydroxylamine (DEHA), 3% of pentamethyldiethylenetriamine (PMDETA), 8% of sulfolane, 8% of dimethyl ether, 8% of p-xylene, and 8% of n-butanol.

[0046] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0047] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 48.5 mL, and the volume of the lean phase is 52.2 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.91 mol CO2 / mol, as Figure 2The absorption rate of the shown solution is 0.011 mol CO2 / mol / s. As Figure 3 After the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.4558 mol / mol, as Figure 4 The initial desorption rate shown is 0.00708 mol CO2 / mol / s, and the desorption efficiency is 50.08%.

[0048] Example 7

[0049] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 25% N-(2-hydroxyethyl)ethylenediamine (AEEA), 3% N-aminoethylpiperazine (AEP), 3% 2-(1-hydroxyethyl)pyridine (HEP), 10% N,N'-diethylethylenediamine (DEEA), 20% N,N-diethylhydroxylamine (DEHA), 1% pentamethyldiethylenetriamine (PMDETA), 2% tert-butylaminoethoxyethanol (TBEE), 3% 2-amino-2-methyl-propanol (AMP), 5% sulfolane, 5% dimethyl ether, 5% p-xylene, 5% n-butanol.

[0050] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0051] Test results: As Figure 5 shown, after the solution is saturated in absorption, a liquid-solid phase transition occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 60.12 mL, and the volume of the lean phase is 40.94 mL. As Figure 1 After the absorbent absorbs for 50 min, the absorption amount of the solution is 1.088 mol CO2 / mol, as Figure 2 The absorption rate of the shown solution is 0.011 mol CO2 / mol / s. As Figure 3 After the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.513 mol / mol, as Figure 4 The initial desorption rate shown is 0.00497 mol CO2 / mol / s, and the desorption efficiency is 47.5%.

[0052] Example 8

[0053] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 30% N-(2-hydroxyethyl)ethylenediamine (AEEA), 13% N,N'-diethylethylenediamine (DEEA), 15% N,N-diethylhydroxylamine (DEHA), 5% pentamethyldiethylenetriamine (PMDETA), 7% sulfolane, 7% dimethyl ether, 7% p-xylene, 7% n-butanol.

[0054] The preparation method of the absorbent, as well as the absorption and desorption experiment processes, are all kept the same as those in Example 1.

[0055] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 45.2 mL, and the volume of the lean phase is 55.9 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.797 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.011 mol CO2 / mol / s. As Figure 3 shown, after the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.545 mol / mol, as Figure 4 shown, the initial desorption rate is 0.00384 mol CO2 / mol / s, and the desorption efficiency is 63.38%.

[0056] Example 9

[0057] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 27% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 1% of N-aminoethylpiperazine (AEP), 1% of 2-(1-hydroxyethyl)pyridine (HEP), 12% of N,N'-diethylethylenediamine (DEEA), 18% of N,N-diethylhydroxylamine (DEHA), 4% of pentamethyldiethylenetriamine (PMDETA), 1% of tert-butylaminoethoxyethanol (TBEE), 1% of 2-amino-2-methyl-propanol (AMP), 6% of sulfolane, 6% of dimethyl ether, 6% of p-xylene, and 6% of n-butanol.

[0058] The preparation method of the absorbent, as well as the absorption and desorption experiment processes, are all kept the same as those in Example 1.

[0059] Test results: As Figure 5 shown, after the solution is saturated with absorption, a liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 42.9 mL, and the volume of the lean phase is 58.15 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 0.603 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.008 mol CO2 / mol / s. As Figure 3 shown, after the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.548 mol / mol, as Figure 4 shown, the initial desorption rate is 0.00641 mol CO2 / mol / s, and the desorption efficiency is 90.8%.

[0060] Example 10

[0061] A biphasic absorbent for CO2 capture is prepared from the following components by mass percentage: 28% of N-(2-hydroxyethyl)ethylenediamine (AEEA), 11% of N,N'-diethylethylenediamine (DEEA), 17% of N,N-diethylhydroxylamine (DEHA), 3% of pentamethyldiethylenetriamine (PMDETA), 8% of sulfolane, 8% of dimethyl ether, 8% of p-xylene, and 8% of n-butanol.

[0062] The preparation method of this absorbent and the processes of absorption and desorption experiments are all the same as those in Example 1.

[0063] Test results: As Figure 5 shown, after the solution is saturated in absorption, a liquid-solid phase change occurs. The upper liquid phase is the lean phase, and the lower liquid phase is the rich phase. The volume of the rich phase is 62.2 mL, and the volume of the lean phase is 38.8 mL. As Figure 1 shown, after the absorbent absorbs for 50 min, the absorption amount of the solution is 1.08 mol CO2 / mol, as Figure 2 shown, the absorption rate of the solution is 0.012 mol CO2 / mol / s. As Figure 3 shown, after the rich phase is desorbed for 100 min, the desorption amount of the solution is 0.545 mol / mol, as Figure 4 shown, the initial desorption rate is 0.0016 mol CO2 / mol / s, and the desorption efficiency is 50.4%.

[0064] The CO2 phase change absorbent adopted in this application realizes efficient capture through the multi-amine gradient coordination and solvent regulation technology. The absorbent is compounded from polyamine substances such as primary amine (AEEA), secondary amine (AEP), pyridine compounds (HEP), and tertiary amine (DEEA) and solvents such as sulfolane and dimethyl ether. Among them, the primary amine provides high reaction activity, the secondary amine contains a piperazine ring to enhance the cycle capacity, the tertiary amine reduces volatility, and the pyridine compounds enhance the density of basic sites; the solvent system optimizes the liquid-liquid equilibrium through aromatic solvents and n-butanol, sulfolane enhances physical absorption, dimethyl ether promotes desorption, and DEHA inhibits degradation.

[0065] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments. Although the components in the formula can be adjusted according to requirements (such as changing the ratio of tert-butylaminoethoxyethanol to AMP), they should all be regarded as equivalent deformations of the present invention. The core of the present invention lies in achieving high desorption rate and high-capacity CO2 capture performance through multi-amine gradient activity design and solvent synergy. Therefore, any equivalent substitution or combination based on the claims (such as using pentamethyldiethylenetriamine and AMP in cooperation) should be included within the protection scope.

[0066] It should be understood that the technical solutions of the embodiments in the specification can be appropriately combined (such as combining the synergistic effects of different amines with solvent regulation) to form other embodiments understandable to those skilled in the art. The scope of the present invention is defined by the appended claims, and any parameter optimization or component fine-tuning based on the present invention does not depart from the spirit of the present invention.

Claims

1. A biphasic absorbent for CO2 capture, characterized in that, It is prepared from the following components by mass percentage: 25%-30% of N-(2-hydroxyethyl)ethylenediamine, 0%-3% of N-aminoethylpiperazine, 0%-3% of 2-(1-hydroxyethyl)pyridine, 10%-13% of N,N'-diethylethylenediamine, 15%-20% of N,N-diethylhydroxylamine, 1%-5% of pentamethyldiethylenetriamine, 0%-2% of tert-butylaminoethoxyethanol, 0%-3% of 2-amino-2-methyl-propanol, 5%-8% of sulfolane, 5%-8% of dimethyl ether, 5%-8% of p-xylene, 5%-8% of n-butanol; after the biphasic absorbent absorbs carbon dioxide, it is divided into a lean phase and a rich phase, and carbon dioxide is concentrated in the rich phase.

2. The biphasic absorbent for CO2 capture according to claim 1, characterized in that, The biphasic absorbent forms a biphasic system after saturated absorption of CO2 at 50 °C, in which the volume percentage of the rich phase is 42-65%, and the CO2 absorption capacity ≥ 0.603 mol / mol amine.

3. The biphasic absorbent for CO2 capture according to claim 1 or 2, characterized in that, The desorption efficiency of the absorbent at 130 °C ≥ 39.9%, and the highest desorption efficiency can reach 90.8%.

4. A method for preparing a biphasic absorbent for CO2 capture according to any one of claims 1 to 3, characterized in that, Weigh the components described in Claim 1 according to the ratio and place them in a container. Stir at 40-60 °C for 15-30 minutes and maintain the rotation speed at 200-400 rpm to form a homogeneous solution; then seal the container and perform ultrasonic dispersion treatment for 10-20 min to obtain a biphasic absorbent, and the ultrasonic power is 150-250 W.

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