A phase-change absorbent for capturing and purifying CO2 in waste gas and its application

Abstract

The present invention belongs to the technical field of CO2 capture and purification, and specifically relates to a phase change absorbent for capturing and purifying CO2 in exhaust gas and its application. The phase change absorbent, by mass percentage, comprises raw materials including: 27%-30% hydroxyethylethylenediamine, 25%-30% pentamethyldiethylenetriamine, 15%-20% diethylene glycol dimethyl ether, 0.1%-0.3% corrosion inhibitor, 0.5%-1.0% antioxidant and the remainder of water. The present invention is suitable for the regeneration of the absorption system of CO2 capture and purification. The phase change can reduce the regeneration energy consumption and regeneration temperature, and increase the regeneration rate through the phase change during the regeneration process. It has the characteristics of large absorption load, high absorption and desorption rate and low regeneration energy consumption, and can make the regeneration energy consumption of the CO2 capture system lower than 2.0GJ / tCO2, which can effectively reduce the CO2 capture energy consumption and reduce the CO2 capture cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of CO2 capture and purification, and in particular relates to a phase change absorbent for capturing and purifying CO2 in waste gas and application thereof. Background Art

[0002] Carbon capture, utilization and storage (CCUS) technology is a necessary means to achieve substantial CO2 emission reductions at this stage.

[0003] Among the many capture technologies, chemical absorption is the most commonly selected flue gas CO2 capture method for CCUS projects due to its technical maturity and application prospects. It is the main technical path for capturing CO2 from large stationary emission sources such as coal-fired and gas-fired power plants at this stage. In the chemical solvent absorption method, organic amine solvents have relatively mature applications in industry due to their high absorption efficiency, renewability, and high purity of desorbed CO2. However, traditional organic amine solvents also have defects such as easy corrosion and degradation, high regeneration energy consumption, and too low cycle load. In recent decades, researchers have been committed to developing new structural modified amines and compound amines, new absorption-desorption processes, and efficient gas-liquid mass transfer equipment to reduce energy consumption in the CO2 absorption-desorption process.

[0004] Chinese invention patent application CN117101347A discloses an ionic liquid-based phase change absorbent for CO2 capture, which includes a functionalized ionic liquid, a phase separation agent and water, wherein the functionalized ionic liquid is triethylenetetraminemethylimidazole or triethylenetetraminepiperazine. The phase change absorbent forms two phases after absorbing CO2, and CO2 exists in both the rich phase and the phase change absorbent. By adjusting the ratio of the ionic liquid, the phase separation agent and the water, the minimum rich phase ratio in the phase change absorbent is only 15%, which is beneficial to reduce the regeneration energy consumption. However, the ionic liquid phase change absorbent has a high viscosity and faces difficulties in industrial application and promotion.

[0005] Chinese invention patent application CN112107966A discloses a non-aqueous liquid-liquid phase-change absorbent for carbon dioxide capture and its application. The phase-change absorbent is composed of primary alcohol amine and composite organic solvent. It is homogeneous before absorbing CO2 and two-phase after absorption. The system is regenerated by heating the rich phase, which reduces the regeneration energy consumption and facilitates recycling. However, in actual industrial applications, the flue gas itself contains water vapor, and the non-aqueous phase-change absorbent cannot guarantee the phase separation under a certain water content.

[0006] Phase change absorbents can effectively reduce regeneration energy consumption and have received widespread attention from researchers. Phase change absorbents are uniform liquid phases. After absorbing CO2, they can be converted into two distinct phases, one of which is a rich phase enriched with more than 95% of the CO2 product, and the other is a lean phase. During desorption, only the rich phase needs to be heated, which can effectively reduce the amount of heated solution, thereby reducing regeneration energy consumption. However, current phase change absorbents still have problems such as low comprehensive decarbonization ability, strong corrosiveness, easy foaming, high desorption energy consumption, high regeneration temperature, and weak anti-oxidation and degradation ability.

[0007] Therefore, the development of phase change absorbents that are resistant to corrosion and degradation, have low regeneration energy consumption, and high cycle load is the key to current research. Summary of the invention

[0008] In view of the defects of high regeneration energy consumption and poor desorption performance of phase change absorbents in the prior art, the present invention provides a phase change absorbent for capturing and purifying CO2 in exhaust gas and its application, opening up a new efficient and economical method for current industry.

[0009] The present invention is achieved through the following technical solutions:

[0010] A phase-change absorbent for capturing and purifying CO2 in exhaust gas. The raw materials of the phase-change absorbent include, by mass percentage, 20%-30% hydroxyethylethylenediamine, 20%-30% pentamethyldiethylenetriamine, 10%-20% diethylene glycol dimethyl ether, 0.01%-0.3% corrosion inhibitor, 0.1%-2.0% antioxidant and the balance water.

[0011] Preferably, the raw materials of the phase change absorber include, by mass percentage: 25%-30% hydroxyethylethylenediamine, 25%-30% pentamethyldiethylenetriamine, 15%-20% diethylene glycol dimethyl ether, 0.1%-0.3% corrosion inhibitor, 0.5%-1.0% antioxidant and the balance water.

[0012] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 29%: 30%: 15%: 25%: 0.2%: 0.8%.

[0013] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28.5%: 30%: 15.5%: 25%: 0.2%: 0.8%.

[0014] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 30%: 16%: 25%: 0.2%: 0.8%.

[0015] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 29%: 17%: 25%: 0.2%: 0.8%.

[0016] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 28%: 18%: 25%: 0.2%: 0.8%.

[0017] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 27%: 28%: 19%: 25%: 0.2%: 0.8%.

[0018] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 27.5%: 18.5%: 25%: 0.2%: 0.8%.

[0019] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 27%: 27%: 20%: 25%: 0.2%: 0.8%.

[0020] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 26%: 20%: 25%: 0.2%: 0.8%.

[0021] Further preferably, the composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 29%: 25%: 20%: 25%: 0.2%: 0.8%.

[0022] Preferably, the corrosion inhibitor is selected from one or more of benzoic acid imidazoline-dimethyl sulfate quaternary ammonium salt, benzoic acid imidazoline-chloromethane quaternary ammonium salt, imidazoline, quaternary ammonium salt, potassium chromate, potassium dichromate, sodium nitrite, sodium nitrate and sodium phosphate.

[0023] Further preferably, the corrosion inhibitor is benzoic acid imidazoline-dimethyl sulfate quaternary ammonium salt or benzoic acid imidazoline-chloromethane quaternary ammonium salt.

[0024] Preferably, the antioxidant is selected from one or more of carbohydrazide, pyrogallol, sodium metavanadate, potassium sodium tartrate, sodium thiosulfate, sodium sulfite, sodium pyrosulfite and sodium bisulfite.

[0025] More preferably, the antioxidant is carbohydrazide or pyrogallol.

[0026] The present invention also relates to a process for capturing and purifying CO2 in exhaust gas using the above-mentioned phase change absorbent. When the absorption system suitable for low partial pressure CO2 capture and purification is applied to a CO2 capture and purification system assembly for CO2 capture and purification, the CO2 capture and purification system assembly includes an absorption tower, a desorption tower, a phase separator and a heat pump. The CO2 capture and purification specifically includes the following parts:

[0027] a.CO2 absorption: Flue gas enters the absorption tower from bottom to top, and the lean liquid absorbent discharged from the phase separator is sprayed from top to bottom into the absorption tower. The two are in countercurrent contact for decarbonization reaction. The temperature of the lean liquid absorbent discharged from the phase separator and entering the absorption tower is controlled at 35-45℃;

[0028] b.CO2 desorption: The rich liquid that has absorbed CO2 gas is discharged from the bottom of the absorption tower and transported through a heat pump. The heat exchange temperature is controlled at 95-105°C. After heat exchange, it enters the desorption tower for desorption;

[0029] c. Regeneration of absorption solvent: The desorbed lean liquid enters the heat exchanger from the lean liquid outlet at the bottom of the desorption tower for heat exchange and cooling. After heat exchange and cooling, the temperature is controlled at 40-50°C and re-enters the absorption tower to start a new absorption process;

[0030] d. Regeneration gas treatment: The regeneration gas desorbed from the rich liquid enters the condenser from the top outlet of the desorption tower for condensation and cooling to 80℃-90℃; the product gas is obtained, and the separated dilute solution continues to enter the desorption tower kettle.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The regenerative stratified phase-change absorbent of the absorption system suitable for CO2 capture and purification can reduce the regeneration energy consumption and regeneration temperature and increase the regeneration rate through phase change in the regeneration process. It has the characteristics of large absorption load, high absorption and desorption rate and low regeneration energy consumption. The regeneration energy consumption of the absorbent combined with the energy-saving process is no more than 2.0 GJ / tCO2, which can effectively reduce the CO2 capture energy consumption and reduce the CO2 capture cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is an energy-saving process flow chart suitable for CO2 capture and purification using a phase change absorption system.

[0034] Among them, the figure numbers are explained as follows: 1. absorption tower, 2. phase separator, 3. heat pump, 4. desorption tower, 5. condenser, 6. heat exchanger. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0036] The absorption system suitable for low partial pressure CO2 capture and purification is a phase change absorption system. The regeneration and stratification phase change absorbent of the phase change absorption system is composed of a base liquid, a stratification agent, a corrosion inhibitor and an antioxidant. The base liquid is a basic absorption liquid, which is used to ensure a large collection load and a high absorption rate of the absorbent, and is composed of hydroxyethylethylenediamine (AEEA) and pentamethyldiethylenetriamine (PMDETA). The stratification agent is used to realize stratification after the absorption system regenerates CO2, realizes the autonomous self-extraction of the organic phase, ensures a large stratification ratio, and thus reduces energy consumption. It is composed of diethylene glycol dimethyl ether and water. The corrosion inhibitor is used to reduce the corrosion of the absorption system to steel (reactors, heat exchange equipment, various storage tanks, pipelines, etc.), and is composed of benzoic acid imidazoline-dimethyl sulfate quaternary ammonium salt (IBDSQAS) or benzoic acid imidazoline-chloromethane quaternary ammonium salt (ICQAB). The antioxidant is used to reduce the thermal degradation and oxidative degradation of the active ingredients of the absorbent and ensure the stability of the absorption system, and is composed of carbohydrazide (CD) or pyrogallol (OTP).

[0037] An energy-saving process for capturing and purifying CO2 in exhaust gas using a phase-change absorbent, such as Figure 1 As shown, the capture and purification system assembly suitable for low partial pressure CO2 includes an absorption tower 1, a phase separator 2, a heat pump 3, a desorption tower 4, a condenser 5, and a heat exchanger 6.

[0038] Energy-saving process for CO2 capture and purification:

[0039] a.CO2 absorption: Flue gas enters absorption tower 1 from bottom to top, and the lean liquid absorbent discharged from phase separator 2 is sprayed from top to bottom into absorption tower 1. The two are in countercurrent contact for decarbonization reaction. The temperature of the lean liquid absorbent discharged from phase separator 2 and entering absorption tower 1 is controlled at 35-45℃;

[0040] b. CO2 desorption: The rich liquid that has absorbed CO2 gas is discharged from the bottom of the absorption tower 1 and transported through the heat pump 3. The heat exchange temperature is controlled at 95-105°C. After heat exchange, it enters the desorption tower 4 for desorption;

[0041] c. Regeneration of absorption solvent: The desorbed lean liquid enters the heat exchanger 6 from the lean liquid outlet at the bottom of the desorption tower 4 for heat exchange and cooling. After heat exchange and cooling, the temperature is controlled at 40-50°C and re-enters the absorption tower 1 to start a new absorption process;

[0042] d. Regeneration gas treatment: The regeneration gas desorbed from the rich liquid enters the condenser 5 from the top outlet of the desorption tower 4 to be condensed and cooled to 80℃-90℃; the product gas is obtained, and the separated dilute solution continues to enter the desorption tower 4 kettle;

[0043] The present invention is discussed below by taking the capture and purification of CO2 from flue gas discharged from a coal-fired power plant as an example.

[0044] The parameters of the absorption tower and desorption tower are shown in Table 1, the flue gas composition is shown in Table 2, and the CO2 capture and purification experimental operating parameters are shown in Table 3. The absorption tower and desorption tower are made of stainless steel and stainless steel corrugated structured packing. The absorption tower, desorption tower and pipeline are wrapped with insulation materials. The regeneration heat comes from the electric heater at the bottom of the desorption tower 4, and the regeneration temperature of the system is controlled by thyristor voltage adjustment.

[0045] Table 1 Absorption tower and desorption tower parameters

[0046]

[0047] Table 2 Flue gas composition

[0048]

[0049] Table 3 CO2 capture and purification experimental operating parameters

[0050]

[0051] Example 1

[0052] The composition and mass ratio of the phase change absorption system are:

[0053] AEEA:PMDETA:Diethylene glycol dimethyl ether:H2O:IBDSQAS:CD=29%:30%:15%:25%:0.2%:0.8%.

[0054] The specific performance parameters of the conventional process and the energy-saving process are shown in Table 4 (a) and Table 4 (b).

[0055] Table 4 (a) Performance parameters of Example 1 using conventional process

[0056]

[0057] Table 4 (b) Performance parameters of the energy-saving process used in Example 1

[0058]

[0059] Example 2

[0060] The composition and mass ratio of the phase change absorption system are:

[0061] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: ICQAB: CD = 28.5%: 30%: 15.5%: 25%: 0.2%: 0.8%. The specific performance parameters of the conventional process and the energy-saving process are shown in Table 5 (a) and Table 5 (b).

[0062] Table 5 (a) Performance parameters of Example 2 using conventional process

[0063]

[0064] Table 5 (b) Performance parameters of Example 2 using energy-saving technology

[0065]

[0066] Example 3

[0067] The composition and mass ratio of the phase change absorption system are:

[0068] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 28%: 30%: 16%: 25%: 0.2%: 0.8%. The specific performance parameters of the conventional process and the energy-saving process are shown in Table 6 (a) and Table 6 (b).

[0069] Table 6 (a) Performance parameters of Example 3 using conventional process

[0070]

[0071] Table 6 (b) Performance parameters of Example 3 using energy-saving technology

[0072]

[0073] Example 4

[0074] The composition and mass ratio of the phase change absorption system are:

[0075] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 28%: 29%: 17%: 25%: 0.2%: 0.8%. The specific performance parameters of the conventional process and the energy-saving process are shown in Table 7 (a) and Table 7 (b).

[0076] Table 7 (a) Performance parameters of Example 4 using conventional process

[0077]

[0078] Table 7 (b) Performance parameters of Example 4 using energy-saving technology

[0079]

[0080] Example 5

[0081] The composition and mass ratio of the phase change absorption system are:

[0082] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 28%: 28%: 18%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 8.

[0083] Table 8 Performance parameters of Example 5 using energy-saving technology

[0084]

[0085] Example 6

[0086] The composition and mass ratio of the phase change absorption system are:

[0087] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 27%: 28%: 19%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 9.

[0088] Table 9 Performance parameters of Example 6 using energy-saving technology

[0089]

[0090] Example 7

[0091] The composition and mass ratio of the phase change absorption system are:

[0092] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: ICQAB: OTP = 28%: 27.5%: 18.5%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 10.

[0093] Table 10 Performance parameters of Example 7 using energy-saving technology

[0094]

[0095] Example 8

[0096] The composition and mass ratio of the phase change absorption system are:

[0097] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: OTP = 27%: 27%: 20%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 11.

[0098] Table 11 Performance parameters of Example 8 using energy-saving technology

[0099]

[0100] Example 9

[0101] The composition and mass ratio of the phase change absorption system are:

[0102] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 28%: 26%: 20%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 12.

[0103] Table 12 Performance parameters of Example 9 using energy-saving technology

[0104]

[0105] Example 10

[0106] The composition and mass ratio of the phase change absorption system are:

[0107] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: OTP = 29%: 25%: 20%: 25%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 13.

[0108] Table 13 Performance parameters of energy-saving process used in Example 10

[0109]

[0110] Comparative Example 1

[0111] The composition and mass ratio of the phase change absorption system are:

[0112] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 20%: 20%: 30%: 29%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 14.

[0113] Table 14 Performance parameters of comparative example 1 using energy-saving process

[0114]

[0115] Comparative Example 2

[0116] The composition and mass ratio of the phase change absorption system are:

[0117] AEEA: PMDETA: diethylene glycol dimethyl ether: H2O: IBDSQAS: CD = 35%: 20%: 25%: 19%: 0.2%: 0.8%. The performance parameters of the specific energy-saving process are shown in Table 15.

[0118] Table 15 Performance parameters of comparative example 2 using energy-saving technology

[0119]

[0120] The mass ratio of the phase change absorbent in Comparative Example 1-2 has changed. Compared with the embodiment of the present invention, the regeneration energy consumption has increased significantly, and the regeneration energy consumption is greater than 2.6 GJ / tCO2; the regeneration rate after running for 72h and 720h is significantly lower than that in the embodiment of the present invention.

[0121] The present invention is applicable to the phase change in the regeneration process of the absorption system for capturing and purifying CO2 in exhaust gas, which can reduce the regeneration energy consumption and regeneration temperature, and improve the regeneration rate. It has the characteristics of large absorption load, high absorption and desorption rate and low regeneration energy consumption. The regeneration energy consumption of the absorbent itself is less than 2.2GJ / tCO2.

[0122] The absorption and desorption coupling process used in the present invention is an energy-saving process suitable for CO2 capture and purification, which can effectively reduce the volume of the boiler, greatly reduce the regeneration energy consumption, reduce the loss of reagents and the degradation of reagents, increase the number of cycles of chemical absorbents, save investment costs, achieve resource recovery and reduce environmental pollution, and make the regeneration energy consumption of the CO2 capture system lower than 2.0GJ / tCO2. Compared with the traditional process, the regeneration energy consumption can be reduced by 0.75-0.85GJ / tCO2.

[0123] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A phase change absorbent for capturing and purifying CO2 in exhaust gas, characterized in that: The raw materials of the phase change absorber include, by mass percentage: 27%-30% hydroxyethylethylenediamine, 25%-30% pentamethyldiethylenetriamine, 15%-20% diethylene glycol dimethyl ether, 0.1%-0.3% corrosion inhibitor, 0.5%-1.0% antioxidant and the balance water; The corrosion inhibitor is selected from one or more of benzoic acid imidazoline-dimethyl sulfate quaternary ammonium salt, benzoic acid imidazoline-chloromethane quaternary ammonium salt, imidazoline, quaternary ammonium salt, potassium chromate, potassium dichromate, sodium nitrite, sodium nitrate and sodium phosphate; The antioxidant is selected from one or more of carbohydrazide, pyrogallol, sodium metavanadate, potassium sodium tartrate, sodium thiosulfate, sodium sulfite, sodium pyrosulfite and sodium bisulfite.

2. The phase change absorber according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 29%: 30%: 15%: 25%: 0.2%: 0.8%.

3. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28.5%: 30%: 15.5%: 25%: 0.2%: 0.8%.

4. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 30%: 16%: 25%: 0.2%: 0.8%.

5. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 29%: 17%: 25%: 0.2%: 0.8%.

6. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 28%: 18%: 25%: 0.2%: 0.8%.

7. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 27%: 28%: 19%: 25%: 0.2%: 0.8%.

8. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 27.5%: 18.5%: 25%: 0.2%: 0.8%.

9. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 27%: 27%: 20%: 25%: 0.2%: 0.8%.

10. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 28%: 26%: 20%: 25%: 0.2%: 0.8%.

11. The phase change absorbent according to claim 1, characterized in that: The composition and mass ratio of the phase change absorber are: hydroxyethylethylenediamine: pentamethyldiethylenetriamine: diethylene glycol dimethyl ether: water: corrosion inhibitor: antioxidant = 29%: 25%: 20%: 25%: 0.2%: 0.8%.

12. The phase change absorbent according to claim 1, characterized in that: The corrosion inhibitor is benzoic acid imidazoline-dimethyl sulfate quaternary ammonium salt or benzoic acid imidazoline-chloromethane quaternary ammonium salt.

13. The phase change absorbent according to claim 1, characterized in that: The antioxidant is carbohydrazide or pyrogallol.

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