A self-heating membrane absorption-electrochemical regeneration coupled co2 capture method

Abstract

The application discloses a kind of self-heating membrane absorption-electrochemical regeneration coupled CO2 capture method, through the reaction heat generated by recycling hollow fiber membrane contactor and the reaction heat is passed into heat exchanger, preheats absorption rich liquid;After preheating, absorption rich liquid is passed into the anode chamber of bipolar membrane electrolytic cell, and the CO2 released by electrolytic effect is collected;And the absorption lean liquid after regeneration discharged by the anode chamber of bipolar membrane electrolytic cell is passed into mixed tank with the lye discharged by cathode chamber, after being mixed evenly, it is backflowed to the shell side of hollow fiber membrane contactor by circulating pump, the above steps are repeated, that is, continuous and stable CO2 capture and absorbent regeneration can be realized.The application carries out CO2 capture by using membrane absorption-electrochemical regeneration coupled mode, and the reaction heat during membrane absorption capture is recycled, compared with traditional heat regeneration process, energy consumption can be reduced by more than 70%, which can effectively reduce the regeneration energy consumption and operating cost.

Description

Technical Field

[0001] This invention relates to the field of CO2 capture technology, specifically to a self-heating membrane absorption-electrochemical regeneration coupled CO2 capture method. Background Technology

[0002] With the advancement of global "dual carbon" goals, the capture technology of low-concentration CO2 (volume fraction 10-15%) in industrial flue gas has become crucial for achieving deep decarbonization. Currently, membrane absorption has been widely studied and initially applied in industrial CO2 capture due to its advantages such as high mass transfer efficiency, compact equipment, and simple operation. Its core principle is to use a hydrophobic and breathable membrane to separate the flue gas from the absorbent, and CO2 permeates through the membrane wall and reacts chemically with the absorbent to achieve capture.

[0003] However, existing membrane absorption CO2 capture technology has two major drawbacks that limit its industrial application: First, the energy consumption for absorbent regeneration is high. Traditional regeneration methods mostly use thermal regeneration (such as steam heating), with regeneration energy consumption as high as 3.5 GJ / ton CO2, accounting for more than 70% of the total energy consumption of the capture system, resulting in high operating costs. Second, the system integration is low. The membrane absorption unit and the absorbent regeneration unit are independent of each other, without energy coupling design. The reaction heat released during the reaction is directly wasted, and additional alkali solution needs to be added during the regeneration process to compensate for the loss, which can easily lead to secondary pollution.

[0004] In existing technologies, although some researchers have attempted to combine membrane absorption with electrochemical regeneration (such as the patent with publication number CN112933879B), this is merely a simple splicing of two units, failing to recover and utilize the heat of reaction, and thus unable to solve the problem of high energy consumption. Furthermore, the absorbent loss during regeneration requires external alkali replenishment, posing a risk of secondary pollution. Simultaneously, the system lacks a self-heating balance control mechanism, resulting in poor operational stability. Moreover, existing coupling technologies largely rely on specialized membrane materials or novel absorbents, which are difficult and costly to develop, making them unsuitable for rapid retrofitting and implementation in existing industrial facilities.

[0005] Therefore, developing a membrane absorption-electrochemical regeneration coupled CO2 capture technology that is low in energy consumption, highly integrated, free from secondary pollution, and highly efficient has become an urgent technical problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a CO2 capture method that couples self-heating membrane absorption with electrochemical regeneration.

[0007] The technical solution of this invention is: a CO2 capture method coupled with a self-heating membrane absorption-electrochemical regeneration system, comprising the following steps: S1. Flue gas pretreatment: The industrial flue gas containing CO2 is sequentially treated by dust removal and desulfurization to remove dust and SO2 impurities from the flue gas, and the pretreated industrial flue gas is obtained. S2. Membrane absorption and capture: The pretreated industrial flue gas is introduced into the tube side of the hollow fiber membrane contactor, and the absorbent is introduced into the shell side of the hollow fiber membrane contactor at the same time. CO2 passes through the membrane wall of the hollow fiber membrane and reacts chemically with the absorbent to form a rich absorbent solution, and releases heat of reaction (about 80kJ / mol CO2) during the reaction. S3, Reaction Heat Recovery Coupling: The reaction heat generated in S2 is recovered and passed into a heat exchanger to preheat the absorption-rich solution that is about to enter the bipolar membrane electrolyzer, thus obtaining the preheated absorption-rich solution. S4. Electrochemical regeneration: The preheated rich absorbent solution is passed into the anode chamber of the bipolar membrane electrolyzer. Under the conditions of electrolysis voltage of 2.5-3.5V and electrolysis temperature of 40-60℃, CO2 is released from the rich absorbent solution through electrolysis. The released CO2 is condensed and dried to obtain CO2 with a purity of ≥99.5%, which can be further used in chemical processes or stored. S5. Closed-loop circulation: The regenerated lean absorbent solution discharged from the anode chamber of the bipolar membrane electrolyzer and the alkaline solution discharged from the cathode chamber are fed into a mixing tank together. After being mixed evenly, the solution is returned to the shell side of the hollow fiber membrane contactor by a circulation pump. Steps S2-S4 are repeated to achieve continuous and stable CO2 capture and absorbent regeneration.

[0008] Furthermore, the industrial flue gas is low-concentration CO2 flue gas from power plants, steel plants, or cement plants, with a CO2 volume fraction of 10-15%.

[0009] Furthermore, the hollow fiber membrane contactor uses a commercially available hydrophobic polytetrafluoroethylene (PTFE) membrane with a pore size of 0.1-0.2 μm and a CO2 absorption rate of ≥95%.

[0010] Description: Commercially available hydrophobic polytetrafluoroethylene (PTFE) membranes possess excellent hydrophobicity and anti-wetting capabilities. Furthermore, the membrane pore size, ranging from 0.1 to 0.2 μm, is within the optimal range for microporous membranes, allowing high-speed diffusion of CO2 molecules while completely blocking liquid phase permeation. This achieves precise separation at the gas-liquid interface, enhancing mass transfer flux and selectivity. PTFE membranes are also resistant to strong acids, strong alkalis, organic solvents, and oxidizing environments, compatible with various absorbents, and exhibit high chemical stability and durability. CO2 flux can reach 0.61–1.35 × 10⁻⁶. -3 mol / (m 2 ·s).

[0011] Furthermore, the absorbent is an amino acid salt-ionic liquid composite absorbent, wherein the volume ratio of the amino acid salt to the ionic liquid in the amino acid salt-ionic liquid composite absorbent is 3-5:1; the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the amino acid salt is any one or more of sodium glycinate (GlyNa), sodium lysine (LysNa), and sodium arginine (ArgNa).

[0012] Note: In membrane absorption and capture, the use of amino acid salt-ionic liquid composite absorbent can significantly reduce regeneration energy consumption, which can be as low as 1.58~2.75 GJ / t CO2, which is more than 30% lower than 3.22~4.0 GJ / t CO2 of 30% MEA solution, thus greatly reducing operating costs; Meanwhile, this composite system avoids the thermal oxidative degradation problem of MEA in the presence of oxygen, can maintain good CO2 absorption efficiency even after multiple uses, and concentrates reaction products in the CO2-rich phase, reducing system viscosity, improving mass transfer efficiency, and facilitating subsequent separation and regeneration.

[0013] Furthermore, an organic enhancer is introduced into the amino acid salt-ionic liquid composite absorbent, wherein the organic enhancer is dimethyl sulfoxide (DMSO) and glycerol (Gly), wherein the amount of dimethyl sulfoxide (DMSO) added is 10-20 wt% and the amount of glycerol (Gly) added is 2-5 wt%.

[0014] Note: By introducing appropriate amounts of dimethyl sulfoxide and glycerol as co-solvents, the viscosity of the system can be reduced by 40-60%, achieving a balance between high absorption capacity and rapid mass transfer. Within the above range, the introduction of dimethyl sulfoxide can maintain the CO2 absorption capacity at a level of >0.8 mol CO2 / mol absorbent, and the electrochemical regeneration efficiency is significantly improved. Introducing glycerol within the above range can assist dimethyl sulfoxide in adjusting the polarity of the system and synergistically stabilizing the zwitterionic structure.

[0015] Furthermore, the hydrophobic polytetrafluoroethylene membrane is subjected to membrane treatment, which involves encapsulating amino acid salt-ionic liquids (AAILs) within hydrophobic core-shell nanoparticles of polyimide (PIM) to form AAILs@PIM nanoparticles, and then embedding the AAILs@PIM nanoparticles into the hydrophobic polytetrafluoroethylene membrane. The steps are as follows: 1) Preparation of AAILs@PIM nanoparticles: AAILs were dissolved in an aqueous phase to form an inner aqueous phase; PIM was dissolved in an organic solvent to form an oil phase; PVA was dissolved in an aqueous phase to form an outer aqueous phase; the inner aqueous phase was then slowly injected into the oil phase to emulsify and form a W / O primary emulsion; the W / O primary emulsion was then injected into the outer aqueous phase to emulsify and form a W / O / W biemulsion; the solvent was then evaporated at a low temperature of 4°C to solidify PIM on the surface of the AAILs droplets, thus forming AAILs@PIM nanoparticles. The content of AAILs in the inner aqueous phase is 0.3~0.5 mol / L, the content of PIM in the oil phase is 1~5 wt%, the content of PVA in the outer aqueous phase is 0.5~1.5 wt%, and the emulsification is performed by a 20~40kHz ultrasonic homogenizer for 10~20 min. 2) Pretreatment of PTFE membrane: The surface of the PTFE membrane is treated with oxygen plasma to introduce -OH and -COOH polar groups; the oxygen plasma treatment power is 50~100W and the time is 5~10min; then the PTFE membrane is immersed in 1~5 vol% γ-aminopropyltriethoxysilane in ethanol solution and reacted at room temperature for 1.5~2h to obtain the pretreated PTFE membrane. 3) Disperse AAILs@PIM nanoparticles in NMP or DMF to obtain a casting solution, wherein the AAILs@PIM nanoparticles in the casting solution are 10-20 wt%; then uniformly coat the casting solution onto a pretreated PTFE membrane, immerse it in water or ethanol for 10-20 min, and then vacuum dry it at 20-40℃ for 24 h to obtain an AAILs@PIM / PTFE composite membrane; wherein the coating amount of the casting solution is 0.1-0.3 mL / cm 2 And during the coating process, ultrasonic treatment at 20~40kHz is applied.

[0016] Description: By encapsulating amino acid salt-ionic liquids (AAILs) within hydrophobic core-shell nanoparticles of polyimide (PIM), and then coating these nanoparticles onto a PTFE membrane, a hybrid membrane is formed. This hybrid membrane leverages the high free volume channels provided by PIM and the high CO2 affinity sites provided by AAILs to synergistically achieve high permeability and high selectivity, enhancing the effectiveness of the hydrophobic PTFE membrane in membrane absorption and capture. Furthermore, it eliminates the need for high-temperature desorption and can be coupled with driving mechanisms such as electric fields and vibrations to further strengthen CO2 capture and absorption, thereby enhancing the stability of the membrane absorption and capture system.

[0017] Furthermore, in S2, a fluctuating external electric field EEF is simultaneously applied to the tube side and shell side of the hollow fiber membrane contactor. The voltage of the fluctuating external electric field EEF is 2~5V, and the fluctuation period is ±1V / s.

[0018] Explanation: By applying a fluctuating external electric field to the system, the redistribution of charged ions can be further induced, thereby weakening the electrostatic interaction between anions and cations, increasing the free volume, and thus significantly improving the enrichment effect of CO2.

[0019] Furthermore, the heat of reaction is recovered through a heat exchange channel located on the shell side of the hollow fiber membrane contactor. Specifically, the heat exchange channel refers to a heat exchange tube wrapped around the outside of the hollow fiber membrane contactor. This heat exchange tube is equipped with a heat-conducting honeycomb copper plate connected to the hollow fiber membrane contactor. The heat exchange tube contains a heat exchange fluid, and its end is connected to the heat exchanger.

[0020] Note: By recovering and utilizing the reaction heat of the hollow fiber membrane contactor, the problem of high energy consumption in CO2 capture can be effectively solved, and the self-heating energy supply for electrochemical regeneration can be achieved. This can reduce the regeneration energy consumption to 0.6-0.8 MWh / ton CO2, which is more than 70% lower than the energy consumption of traditional thermal regeneration processes and more than 40% lower than the energy consumption of existing simple membrane absorption-electrochemical regeneration coupling processes.

[0021] Furthermore, during membrane absorption and capture, the reaction temperature of the hollow fiber membrane contactor and the preheating temperature of the electrolytic cell are monitored in real time by a temperature sensor. The signals of the reaction temperature and preheating temperature are transmitted to the controller. The PLC controller then adjusts the flow regulating valve of the heat exchanger and the speed of the circulating pump in conjunction with the controller to match the amount of heat recovered from the reaction with the preheating requirement of the electrolytic cell. This maintains the reaction temperature of the hollow fiber membrane contactor at 30-40℃ and the preheating temperature of the electrolytic cell at 40-60℃, with a control accuracy of ±2℃.

[0022] Note: By setting the above-mentioned temperature sensor and other components in the system, the CO2 capture system of the present invention can have a self-heating balance control mechanism, which can monitor the reaction temperature and the preheating temperature of the electrolyzer in real time, thereby adjusting the dynamic effect, ensuring the effect of membrane absorption capture and electrochemical regeneration, and improving the operational stability of the system.

[0023] The beneficial effects of this invention are: (1) The energy consumption of the CO2 capture method of the present invention is significantly reduced. Through reaction heat recovery coupling, the self-heating energy supply of electrochemical regeneration can be realized, and the regeneration energy consumption is reduced to 0.6-0.8 MWh / ton CO2, which is more than 70% lower than the energy consumption of traditional thermal regeneration process and more than 40% lower than the energy consumption of existing simple membrane absorption-electrochemical regeneration coupling process.

[0024] (2) The CO2 capture method of the present invention has no secondary pollution and can realize closed-loop circulation of absorbent. The OH generated in the cathode chamber - Ions directly replenish the absorbent loss without the need for additional alkali solution, thus avoiding alkali consumption and wastewater discharge, and meeting environmental protection requirements.

[0025] (3) The CO2 capture method of the present invention has high system stability. By setting a self-heating balance control mechanism, it can respond to the fluctuations of flue gas composition and reaction temperature in real time, ensuring that the CO2 capture efficiency (≥95%) and absorbent regeneration efficiency (≥98%) are stable, and the decarbonized flue gas can be directly discharged in compliance with standards.

[0026] (4) The CO2 capture method of the present invention has a wide range of applications and can be adapted to various low-concentration CO2 flue gas treatment scenarios such as power plants, steel plants, and cement plants. It can be directly connected to the transformation of existing industrial facilities. At the same time, the captured high-purity CO2 (≥99.5%) can be directly used in chemical utilization processes such as methanol synthesis and urea production, which is highly practical. Detailed Implementation

[0027] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0028] Example 1: A CO2 capture method using a self-heating membrane absorption-electrochemical regeneration coupling, comprising the following steps: S1. Flue gas pretreatment: Industrial flue gas containing CO2 is pretreated at 80 Nm³ / h. 3 A flow rate of [amount] / h is fed into a bag filter and an alkaline spray desulfurizer, where the flue gas undergoes dust removal and desulfurization treatments to remove dust and SO2 impurities, ensuring that the outlet SO2 concentration is ≤50mg / Nm³. 3 The pretreated industrial flue gas is obtained; it should be noted that the CO2-containing industrial flue gas mentioned is low-concentration CO2 flue gas from power plants, steel plants or cement plants, with a CO2 volume fraction of 12%; S2, Membrane absorption and capture: The pretreated industrial flue gas is then captured at 80 Nm³. 3 A flow rate of 8 L / h is introduced into the tube side of the hollow fiber membrane contactor, the circulation flow rate is 8 L / h, the system pressure is controlled at 0.15 MPa, the reaction temperature is maintained at 35℃, and the absorbent is introduced into the shell side of the hollow fiber membrane contactor. CO2 passes through the membrane wall of the hollow fiber membrane and reacts chemically with the absorbent to form a rich absorbent solution. During the reaction, a heat of reaction of about 80 kJ / mol CO2 is released. The hollow fiber membrane contactor uses a commercially available hydrophobic polytetrafluoroethylene (PTFE) membrane with a pore size of 0.15 μm and a CO2 absorption rate of ≥95%. The absorbent is an amino acid salt-ionic liquid composite absorbent, wherein the volume ratio of the amino acid salt to the ionic liquid in the amino acid salt-ionic liquid composite absorbent is 4:1. The ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the amino acid salt is sodium glycine (GlyNa). S3, Reaction Heat Recovery Coupling: The reaction heat generated in S2 is recovered and passed into a heat exchanger to preheat the absorption-rich solution that is about to enter the bipolar membrane electrolyzer, thus obtaining the preheated absorption-rich solution. The heat of reaction is recovered through a heat exchange channel located on the shell side of the hollow fiber membrane contactor. Specifically, the heat exchange channel refers to a heat exchange tube wrapped around the outside of the hollow fiber membrane contactor. This heat exchange tube is equipped with a heat-conducting honeycomb copper plate connected to the hollow fiber membrane contactor. The heat exchange tube contains a heat exchange fluid, and its end is connected to the heat exchanger. It should be noted that both the heat exchange fluid and the heat exchanger are commercially available. S4. Electrochemical Regeneration: The preheated rich absorbent solution is passed into the anode chamber of a bipolar membrane electrolyzer. Under the conditions of an electrolysis voltage of 3.0V and an electrolysis temperature of 50℃, CO2 is released from the rich absorbent solution through electrolysis. The released CO2 is then condensed and dried in a condenser to obtain CO2 with a purity ≥99.5%, which can be further utilized in chemical processes or stored. Meanwhile, OH- is generated in the cathode chamber. - Ions, concentration maintained at 0.5 mol / L; S5. Closed-loop circulation: The regenerated lean absorbent solution discharged from the anode chamber of the bipolar membrane electrolyzer and the alkaline solution discharged from the cathode chamber are fed into a mixing tank together. After being mixed evenly, the solution is returned to the shell side of the hollow fiber membrane contactor by a circulation pump. Steps S2-S4 are repeated to achieve continuous and stable CO2 capture and absorbent regeneration.

[0029] Meanwhile, during membrane absorption and capture, the reaction temperature of the hollow fiber membrane contactor and the preheating temperature of the electrolyzer are monitored in real time by temperature sensors. The signals of reaction temperature and preheating temperature are transmitted to the controller, which adjusts the flow regulating valve of the heat exchanger and the speed of the circulating pump through the PLC controller (Siemens S7-200) to match the amount of reaction heat recovery with the preheating requirements of the electrolyzer, so that the reaction temperature of the hollow fiber membrane contactor is maintained at 35℃ and the preheating temperature of the electrolyzer is maintained at 50℃, with a control accuracy of ±2℃.

[0030] Example 2: This example differs from Example 1 in that the hollow fiber membrane contactor uses a commercially available hydrophobic polytetrafluoroethylene (PTFE) membrane with a pore size of 0.1 μm and a CO2 absorption rate ≥95%; the absorbent is an amino acid salt-ionic liquid composite absorbent, with a volume ratio of amino acid salt to ionic liquid of 3:1; the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the amino acid salt is sodium lysine (LysNa).

[0031] Example 3: This example differs from Example 1 in that the hollow fiber membrane contactor uses a commercially available hydrophobic polytetrafluoroethylene (PTFE) membrane with a pore size of 0.2 μm and a CO2 absorption rate ≥95%; the absorbent is an amino acid salt-ionic liquid composite absorbent, with a volume ratio of amino acid salt to ionic liquid of 5:1; the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the amino acid salt is sodium arginine (ArgNa).

[0032] Example 4: The difference between this example and Example 1 is that the preheated rich absorbent solution is introduced into the anode chamber of the bipolar membrane electrolyzer. Under the conditions of electrolysis voltage of 2.5V and electrolysis temperature of 40℃, CO2 is released from the rich absorbent solution through electrolysis.

[0033] Example 5: The difference between this example and Example 1 is that the preheated rich absorbent solution is introduced into the anode chamber of the bipolar membrane electrolyzer. Under the conditions of electrolysis voltage of 3.5V and electrolysis temperature of 60℃, CO2 is released from the rich absorbent solution through electrolysis.

[0034] Example 6: The difference between this example and Example 1 is that the reaction temperature of the hollow fiber membrane contactor is maintained at 30°C and the preheating temperature of the electrolytic cell is maintained at 60°C.

[0035] Example 7: The difference between this example and Example 1 is that the reaction temperature of the hollow fiber membrane contactor is maintained at 40°C, and the preheating temperature of the electrolytic cell is maintained at 40°C.

[0036] Example 8: This example differs from Example 1 in that an organic enhancer is introduced into the amino acid salt-ionic liquid composite absorbent. The organic enhancer is dimethyl sulfoxide (DMSO) and glycerol (Gly), wherein the amount of dimethyl sulfoxide (DMSO) added is 18 wt% and the amount of glycerol (Gly) added is 3 wt%.

[0037] Example 9: This example differs from Example 8 in that the amount of dimethyl sulfoxide (DMSO) added is 10 wt%, and the amount of glycerol (Gly) added is 2 wt%.

[0038] Example 10: This example differs from Example 8 in that the amount of dimethyl sulfoxide (DMSO) added is 20 wt%, and the amount of glycerol (Gly) added is 5 wt%.

[0039] Example 11: This example differs from Example 1 in that the hydrophobic polytetrafluoroethylene membrane undergoes membrane treatment. The membrane treatment involves encapsulating amino acid salt-ionic liquids (AAILs) within hydrophobic core-shell nanoparticles of polyimide (PIM) to form AAILs@PIM nanoparticles, and then embedding these AAILs@PIM nanoparticles into the hydrophobic polytetrafluoroethylene membrane. The steps are as follows: 1) Preparation of AAILs@PIM nanoparticles: AAILs were dissolved in an aqueous phase to form an inner aqueous phase; PIM was dissolved in an organic solvent to form an oil phase; PVA was dissolved in an aqueous phase to form an outer aqueous phase; the inner aqueous phase was then slowly injected into the oil phase to emulsify and form a W / O primary emulsion; the W / O primary emulsion was then injected into the outer aqueous phase to emulsify and form a W / O / W biemulsion; the solvent was then evaporated at a low temperature of 4°C to solidify PIM on the surface of the AAILs droplets, thus forming AAILs@PIM nanoparticles. The inner aqueous phase contains 0.4 mol / L AAILs, the oil phase contains 4.5 wt% PIM, the outer aqueous phase contains 1.2 wt% PVA, and the emulsification is performed using a 30kHz ultrasonic homogenizer for 18 min. 2) Pretreatment of PTFE membrane: The surface of the PTFE membrane was treated with oxygen plasma to introduce -OH and -COOH polar groups; the oxygen plasma treatment power was 80W and the time was 7min; then the PTFE membrane was immersed in an ethanol solution of 4.2 vol% γ-aminopropyltriethoxysilane and reacted at room temperature for 1.8h to obtain the pretreated PTFE membrane. 3) AAILs@PIM nanoparticles were dispersed in DMF to obtain a casting solution, wherein the AAILs@PIM nanoparticles in the casting solution were 15 wt%; the casting solution was then uniformly coated onto a pretreated PTFE membrane, immersed in water for 15 min, and subsequently vacuum dried at 35℃ for 24 h to obtain an AAILs@PIM / PTFE composite membrane; wherein the coating amount of the casting solution was 0.2 mL / cm². 2 And during the coating process, 30kHz ultrasound is applied.

[0040] Example 12: This example differs from Example 11 in that the AAILs in the inner aqueous phase are 0.3 mol / L, the PIM in the oil phase is 1 wt%, the PVA in the outer aqueous phase is 0.5 wt%, and the emulsification is performed using a 20kHz ultrasonic homogenizer for 10 min.

[0041] Example 13: This example differs from Example 11 in that the AAILs in the inner aqueous phase are 0.5 mol / L, the PIM in the oil phase is 5 wt%, the PVA in the outer aqueous phase is 1.5 wt%, and the emulsification is performed using a 40kHz ultrasonic homogenizer for 20 min.

[0042] Example 14: This example differs from Example 11 in that oxygen plasma is used to treat the surface of the PTFE membrane to introduce -OH and -COOH polar groups; wherein, the oxygen plasma treatment power is 50W and the time is 5min; then the PTFE membrane is immersed in 1 vol% γ-aminopropyltriethoxysilane in ethanol solution and reacted at room temperature for 1.5h to obtain the pretreated PTFE membrane.

[0043] Example 15: This example differs from Example 11 in that oxygen plasma is used to treat the surface of the PTFE membrane to introduce -OH and -COOH polar groups; wherein, the oxygen plasma treatment power is 100W and the time is 10min; then the PTFE membrane is immersed in 5 vol% γ-aminopropyltriethoxysilane in ethanol solution and reacted at room temperature for 2h to obtain the pretreated PTFE membrane.

[0044] Example 16: This example differs from Example 11 in that AAILs@PIM nanoparticles are dispersed in DMF to obtain a casting solution, wherein the AAILs@PIM nanoparticles in the casting solution are 10 wt%; the casting solution is then uniformly coated onto a pretreated PTFE membrane, immersed in water for 10 min, and subsequently vacuum dried at 20°C for 24 h to obtain an AAILs@PIM / PTFE composite membrane; wherein the coating amount of the casting solution is 0.1 mL / cm². 2 And during the coating process, 20kHz ultrasound is applied.

[0045] Example 17: This example differs from Example 11 in that AAILs@PIM nanoparticles are dispersed in NMP to obtain a casting solution, wherein the AAILs@PIM nanoparticles in the casting solution are 20 wt%; the casting solution is then uniformly coated onto a pretreated PTFE membrane, immersed in ethanol for 20 min, and subsequently vacuum dried at 40 °C for 24 h to obtain an AAILs@PIM / PTFE composite membrane; wherein the coating amount of the casting solution is 0.3 mL / cm². 2 And during the coating process, 40kHz ultrasound is applied.

[0046] Example 18: The difference between this example and Example 1 is that in S2, a fluctuating external electric field EEF is simultaneously applied to the tube side and shell side of the hollow fiber membrane contactor. The voltage of the fluctuating external electric field EEF is 2~5V, and the fluctuation period is ±1V / s. Specifically, the fluctuating external electric field EEF fluctuates periodically between 2V and 5V, and the adjustment value per second is ±1V.

[0047] Example 19: The difference between this example and Example 11 is that, in S2, a fluctuating external electric field EEF is simultaneously applied to the tube side and shell side of the hollow fiber membrane contactor. The voltage of the fluctuating external electric field EEF is 2~5V, and the fluctuation period is ±1V / s. Specifically, the fluctuating external electric field EEF fluctuates periodically between 2V and 5V, and the adjustment value per second is ±1V.

[0048] Experimental example: A system is now constructed using the CO2 capture method of the present invention, and the apparatus used in the system is as follows: (1) Flue gas pretreatment module: bag filter (processing capacity 100 Nm³) 3 / h), alkaline spray desulfurizer (spray liquid is 8% NaOH solution, spray flow rate 2L / h); (2) Membrane absorption module: Commercial PTFE hollow fiber membrane contactor, such as Pall PTFE membrane module, with a membrane pore size of 0.15μm and an effective area of ​​2m². 2 The shell side is equipped with a stainless steel heat exchange channel; (3) Heat exchange coupling module: plate heat exchanger (heat exchange area 0.5m²) 2 Heat transfer coefficient 1000W / (m 2 ·℃)); (4) Bipolar membrane electrolysis regeneration module: Commercial bipolar membrane electrolyzer (effective area 0.1m²) 2 The bipolar membrane is of the FumasepFBM type, with IrO2-Ta2O5 / Ti as the anode and Ni foam as the cathode. (5) Circulation module: magnetically driven circulation pump (flow range 5-10L / h), mixing tank (volume 5L), flow metering valve (accuracy ±0.1L / h), pressure regulating valve (adjustment range 0.1-0.2MPa); (6) Control components: PT100 temperature sensor (accuracy ±0.1℃), PLC controller (Siemens S7-200).

[0049] Meanwhile, simulated industrial flue gas was used as the experimental sample, as shown in Table 1 below: Table 1. Content of various components in simulated industrial flue gas

[0050] Prepare a condenser dryer (cooling temperature 5℃) and a gas flow meter (accuracy ±0.5 Nm). 3 / h), CO2 analyzer (detection accuracy ±0.1%), running the CO2 capture method of Example 1 for 72h, the test results are as follows: 1) CO2 capture efficiency: average 96.2%, CO2 volume fraction in flue gas after decarbonization ≤0.46%, meeting industrial emission requirements; 2) CO2 purity: After condensation and drying, the CO2 purity is 99.7%, which can be directly used in chemical applications; 3) Absorbent regeneration efficiency: 98.5% on average. After 72 hours of circulation, the absorbent performance showed no significant decline and no need to replenish the alkali solution. 4) Regeneration energy consumption: average 0.72 MWh / ton CO2, a 71.2% reduction compared to the traditional thermal regeneration process (2.5 MWh / ton CO2); 5) System stability: Within 72 hours, the reaction temperature and electrolysis temperature fluctuations are ≤±1℃, the circulation flow is stable, and there are no problems such as membrane fouling or absorbent leakage.

[0051] Meanwhile, in order to further explore the impact of different CO2 capture methods on the capture effect, the following investigation was conducted: Investigation 1: The effect of different absorbent ratios on the capture effect Using the same system and experimental procedures as in Example 1, only the volume ratio of amino acid salt to ionic liquid was changed. Three groups of experiments were set up with ratios of 3:1, 4:1, and 5:1, respectively. Each group was run for 24 hours to test the CO2 capture efficiency and regeneration energy consumption. The results are shown in Table 2 below: Table 2 Effect of different absorbent ratios on collection efficiency

[0052] Conclusion: As can be seen from the results in Table 2 above, the optimal ratio of amino acid salt to ionic liquid is 4:1, which results in the highest CO2 capture efficiency, moderate regeneration energy consumption, and best absorption stability.

[0053] Investigation 2: The Influence of Different Membrane Absorption and Capture Systems on Capture Efficiency The system apparatus and experimental procedures of Examples 8, 11, 18, and 19 were adopted. The remaining system apparatus and experimental procedures were the same as those of Example 1. Each group was run for 24 hours to test CO2 capture efficiency and regeneration energy consumption. The results are shown in Table 3 below: Table 3. Effects of different membrane absorption and capture systems on capture efficiency

[0054] Conclusions: As shown in Table 3 above, introducing a certain amount of dimethyl sulfoxide and glycerol as co-solvents can further improve the CO2 absorption capacity, achieving a balance between high absorption capacity and rapid mass transfer. Compared with traditional PTFE membranes, the CO2 capture efficiency and regeneration energy consumption of AAILs@PIM / PTFE composite membranes are significantly optimized, significantly enhancing the membrane absorption and capture effect of PTFE membranes in this system. Furthermore, the introduction of an EEF fluctuating external electric field improves the performance of both PTFE membrane + amino acid salt-ionic liquid composite absorbent and AAILs@PIM / PTFE composite membrane + ionic liquid composite absorbent, with the effect being more pronounced on AAILs@PIM / PTFE composite membrane + ionic liquid composite absorbent.

[0055] Meanwhile, experiments were conducted to test the effects of different amino acid salt-ionic liquid composite absorbents and AAILs@PIM / PTFE composite membranes on the capture efficiency. Each group ran for 24 hours, and the CO2 capture efficiency and regeneration energy consumption were tested. The results are shown in Tables 4 and 5 below: Table 4. Effects of different amino acid salt-ionic liquid composite absorbents on the capture efficiency.

[0056] Conclusion: As shown in Table 4 above, the optimal ratio of dimethyl sulfoxide and glycerol is achieved when the addition amounts are 18 wt% and 3 wt%, respectively, resulting in the highest CO2 capture efficiency, moderate regeneration energy consumption, and best absorption stability.

[0057] Table 5. Effects of different AAILs@PIM / PTFE composite membranes on capture efficiency

[0058] Conclusion: As shown in Table 5 above, the performance of AAILs@PIM / PTFE composite membranes prepared under different process conditions varies. Among them, the CO2 capture efficiency and regeneration energy consumption of AAILs@PIM / PTFE composite membranes (L11) and (L15) are the optimal schemes. However, the process energy consumption of L15 is higher than that of L11. Therefore, considering the production cost and other factors, the process of AAILs@PIM / PTFE composite membrane of L11 is the optimal process.

[0059] Investigation 3: The Effect of Different Electrolysis Voltages on Regeneration Efficiency Using the same system apparatus and experimental procedures as in Example 1, only the electrolysis voltage of the bipolar membrane electrolyzer was changed. Three sets of experiments were set at 2.5V, 3.0V, and 3.5V respectively, and each set was run for 24 hours. The regeneration efficiency of the absorbent and the purity of CO2 were tested, and the results are shown in Table 6 below: Table 6. Effect of different electrolysis voltages on regeneration efficiency

[0060] Conclusion: As can be seen from the results in Table 6 above, when the electrolysis voltage is 3.0V, the absorbent regeneration efficiency, CO2 purity and electrolysis energy consumption reach the best balance, which is the optimal electrolysis voltage.

Claims

1. A self-heating membrane absorption-electrochemical regeneration coupled CO2 capture method, characterized in that, Includes the following steps: S1. Flue gas pretreatment: The industrial flue gas containing CO2 is sequentially treated by dust removal and desulfurization to remove dust and SO2 impurities from the flue gas, and the pretreated industrial flue gas is obtained. S2. Membrane absorption and capture: The pretreated industrial flue gas is introduced into the tube side of the hollow fiber membrane contactor, and the absorbent is introduced into the shell side of the hollow fiber membrane contactor at the same time. CO2 passes through the membrane wall of the hollow fiber membrane and reacts chemically with the absorbent to form a rich absorbent solution, and releases heat of reaction during the reaction process. S3, Reaction Heat Recovery Coupling: The reaction heat generated in S2 is recovered and passed into a heat exchanger to preheat the absorption-rich solution that is about to enter the bipolar membrane electrolyzer, thus obtaining the preheated absorption-rich solution. S4. Electrochemical regeneration: The preheated rich absorbent solution is passed into the anode chamber of the bipolar membrane electrolyzer. Under the conditions of electrolysis voltage of 2.5-3.5V and electrolysis temperature of 40-60℃, CO2 is released from the rich absorbent solution through electrolysis. The released CO2 is condensed and dried to obtain CO2 with a purity of ≥99.5%, which can be further used in chemical processes or stored. S5. Closed-loop circulation: The regenerated lean absorbent solution discharged from the anode chamber of the bipolar membrane electrolyzer and the alkaline solution discharged from the cathode chamber are fed into a mixing tank together. After being mixed evenly, the solution is returned to the shell side of the hollow fiber membrane contactor by a circulation pump. Steps S2-S4 are repeated to achieve continuous and stable CO2 capture and absorbent regeneration.

2. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, The industrial flue gas is low-concentration CO2 flue gas from power plants, steel plants, or cement plants, with a CO2 volume fraction of 10-15%.

3. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, The hollow fiber membrane contactor uses a hydrophobic polytetrafluoroethylene membrane with a pore size of 0.1-0.2 μm and a CO2 absorption rate of ≥95%.

4. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, An absorbent is introduced into the shell side of the hollow fiber membrane contactor. The absorbent is an amino acid salt-ionic liquid composite absorbent, wherein the volume ratio of the amino acid salt to the ionic liquid in the amino acid salt-ionic liquid composite absorbent is 3-5:

1. The ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and the amino acid salt is any one or more of sodium glycinate (GlyNa), sodium lysine (LysNa), and sodium arginine (ArgNa).

5. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 4, characterized in that, An organic enhancer is introduced into the amino acid salt-ionic liquid composite absorbent, wherein the organic enhancer is dimethyl sulfoxide (DMSO) and glycerol (Gly), wherein the amount of dimethyl sulfoxide (DMSO) added is 10-20 wt% and the amount of glycerol (Gly) added is 2-5 wt%.

6. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 4, characterized in that, The hydrophobic polytetrafluoroethylene (PTFE) membrane is subjected to membrane treatment, which involves encapsulating amino acid salt-ionic liquids (AAILs) within hydrophobic core-shell nanoparticles of polyimide (PIM) to form AAILs@PIM nanoparticles, and then embedding the AAILs@PIM nanoparticles into the hydrophobic PTFE membrane. The steps are as follows: 1) Preparation of AAILs@PIM nanoparticles: AAILs were dissolved in an aqueous phase to form an inner aqueous phase; PIM was dissolved in an organic solvent to form an oil phase; PVA was dissolved in an aqueous phase to form an outer aqueous phase; the inner aqueous phase was then slowly injected into the oil phase to emulsify and form a W / O primary emulsion; the W / O primary emulsion was then injected into the outer aqueous phase to emulsify and form a W / O / W biemulsion; the solvent was then evaporated at a low temperature of 4°C to solidify PIM on the surface of the AAILs droplets, thus forming AAILs@PIM nanoparticles. The content of AAILs in the inner aqueous phase is 0.3~0.5 mol / L, the content of PIM in the oil phase is 1~5 wt%, the content of PVA in the outer aqueous phase is 0.5~1.5 wt%, and the emulsification is performed by a 20~40kHz ultrasonic homogenizer for 10~20 min. 2) Pretreatment of PTFE membrane: The surface of the PTFE membrane is treated with oxygen plasma; the power of the oxygen plasma treatment is 50~100W and the time is 5~10min; then the PTFE membrane is immersed in 1~5 vol% γ-aminopropyltriethoxysilane in ethanol solution and reacted at room temperature for 1.5~2h to obtain the pretreated PTFE membrane. 3) Disperse AAILs@PIM nanoparticles in NMP or DMF to obtain a casting solution, wherein the AAILs@PIM nanoparticles in the casting solution are 10-20 wt%; then uniformly coat the casting solution onto a pretreated PTFE membrane, immerse it in water or ethanol for 10-20 min, and then vacuum dry it at 20-40℃ for 24 h to obtain an AAILs@PIM / PTFE composite membrane; wherein the coating amount of the casting solution is 0.1-0.3 mL / cm 2 And during the coating process, ultrasonic treatment at 20~40kHz is applied.

7. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, In S2, a fluctuating external electric field EEF is simultaneously applied to the tube side and shell side of the hollow fiber membrane contactor. The voltage of the fluctuating external electric field EEF is 2~5V, and the fluctuation period is ±1V / s.

8. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, The heat of reaction is recovered through a heat exchange channel located in the shell side of the hollow fiber membrane contactor.

9. The CO2 capture method based on a self-heating membrane absorption-electrochemical regeneration coupling according to claim 1, characterized in that, During membrane absorption and capture, the reaction temperature of the hollow fiber membrane contactor and the preheating temperature of the electrolytic cell are monitored in real time by temperature sensors. The signals of reaction temperature and preheating temperature are transmitted to the controller. The PLC controller is used to adjust the flow regulating valve of the heat exchanger and the speed of the circulating pump in conjunction with the controller, so that the amount of reaction heat recovery matches the preheating requirement of the electrolytic cell. This keeps the reaction temperature of the hollow fiber membrane contactor at 30-40℃ and the preheating temperature of the electrolytic cell at 40-60℃, with a control accuracy of ±2℃.

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