Electrode, device and method for solid-phase adsorption and capture of CO2

Abstract

The invention discloses a solid-phase adsorption and capture CO2 electrode, device and method, the solid-phase adsorption and capture CO2 electrode comprises an electrode unit, the electrode unit comprises two cathode layers, an anode layer located between the two cathode layers, and current collectors located on the sides, away from the anode layer, of the cathode layers, the electrolyte layer, the diaphragm and the electrolyte layer are positioned between the anode layer and the cathode layer and are arranged in sequence; wherein the number of the electrode unit is at least one. The electrode unit in the electrode for adsorbing and capturing CO2 in the solid phase is arranged to be of a sandwich structure of'cathode + anode + cathode ', gas-solid interface mass transfer in the CO2 capturing process is enhanced through the structural design, the requirement that the anode layer balances charges is met, meanwhile, the CO2 capturing area of the cathode layer is enlarged, and the carbon capturing efficiency is improved. In addition, compared with a traditional liquid-phase carbon capture method, the solid-phase adsorption CO2 capture electrode, device and method disclosed by the invention have more advantages in capture efficiency and energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 capture, and particularly to a solid-phase adsorption CO2 capture electrode, device and method. Background Art

[0002] The large-scale use of fossil fuels has led to a sharp increase in carbon emissions, having a profound impact on the global climate pattern. Currently, carbon emissions from distributed sources account for approximately half of the global total emissions, and low-concentration CO2 emissions targeted by flue gas capture and direct air capture are the main emission sources. Among them, flue gas capture technology mainly targets large emission sources such as coal-fired power plants, and realizes emission reduction by efficiently capturing CO2 in flue gas; while direct air capture technology is dedicated to directly separating and storing CO2 from the atmospheric environment, further broadening the boundaries of carbon emission reduction. However, although the existing amine absorption method in industry is relatively mature in technology, its inherent limitations such as high regeneration energy consumption, poor solvent thermal stability, and easy corrosion of equipment, especially in the low-concentration CO2 capture scenario, the aggravation of solvent entrainment and oxidation phenomena directly lead to a significant increase in the capture cost.

[0003] In recent years, electrochemically mediated carbon capture technology, as an emerging emission reduction means, can operate at normal temperature and pressure, directly acting on target molecules rather than the surrounding environmental medium, showing relatively energy-saving potential, and having the characteristics of plug-and-play and high integration. However, existing electrochemically mediated carbon capture technologies generally rely on the continuous operation of a liquid-phase system, requiring sufficient dissolution of carbon dioxide absorbents in specific solvents, thereby significantly increasing the amount of electrolyte solution used and resulting in a large overall floor area of the device. And the system devices involved not only consume high energy during operation, but also have complex operation processes, and these factors together constitute the main challenges and limitations faced by current electrochemically mediated carbon capture technology in practical applications.

[0004] Based on this, it is particularly important to develop efficient and low-energy-consuming CO2 capture technology. Summary of the Invention

[0005] In order to solve the problems of large consumption of electrolyte solution, high energy consumption and large floor area of equipment in existing CO2 capture technology, one of the purposes of the present invention is to provide a solid-phase adsorption CO2 capture electrode.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: Provide a solid-phase adsorption CO2 capture electrode, which includes an electrode unit. The electrode unit includes a cathode layer, the cathode layer is two layers, an anode layer located between the two cathode layers, a current collector located on the cathode layer and on the side far from the anode layer, and electrolyte layers, a separator and an electrolyte layer arranged in sequence between the anode layer and the cathode layer; wherein, the number of electrode units is at least 1;

[0007] The cathode layer includes a carbon substrate and a conductive material located on the carbon substrate and loaded with a first redox carrier;

[0008] The anode layer includes a carbon substrate and a conductive material located on the carbon substrate and loaded with a second redox carrier;

[0009] The electrolyte layer includes a conductive layer and an electrolyte filled in the conductive layer.

[0010] Based on the above technical solutions, the present invention can be further improved as follows:

[0011] Further, the oxidation potential value required for the first redox carrier to release CO2 is more negative than the potential value at which the second redox carrier undergoes a reduction reaction.

[0012] Further, the first redox carrier contains C=O or / and C=N groups.

[0013] Further, the first redox carrier is any one of monomers, polymers, and their derivatives of quinone, pyridine, phenazine, and conductive metal-organic frameworks;

[0014] The second redox carrier is any one of ferrocene, 1,1'-diethylferrocene, n-octylferrocene, polyvinylferrocene, lithium iron phosphate, lithium cobaltate, and lithium manganate;

[0015] The conductive material is any one of graphene, carbon nanotubes, porous carbon, and conductive carbon black;

[0016] The carbon substrate is carbon paper or carbon cloth.

[0017] Further, the conductive layer is a porous conductive material, and the electrolyte is any one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, and ionic liquids;

[0018] The separator is a polymer;

[0019] The current collector is a metal mesh, and the mesh number of the metal mesh is 50-200.

[0020] The second object of the present invention is to provide a solid-phase adsorption and capture CO2 device. The solid-phase adsorption and capture CO2 device includes a housing, an inner cavity that is open and located inside the housing, a cover plate that is connected to the housing and located at the opening of the inner cavity, an air inlet and an air outlet that penetrate through the cover plate and communicate with the inner cavity, an electrochemical capture circuit unit located inside the inner cavity, a solid-phase adsorption and capture CO2 electrode according to any one of claims 1-5 mounted on the electrochemical capture circuit unit, and a cathode connecting rod and an anode connecting rod that penetrate through the cover plate at one end and are both connected to the electrochemical capture circuit unit.

[0021] Further, the electrochemical capture circuit unit includes a cathode connection plate and an anode connection plate that are symmetrically positioned and located in the inner cavity. The cathode connection plate and the anode connection plate are both provided with card slots for mounting the solid-phase adsorption and capture CO2 electrodes. The card slot on the cathode connection plate is provided with a cathode metal clip. Among them, the cathode layer is connected to the cathode connection plate through the cathode metal clip, the anode layer is connected to the anode connection plate through a wire, the cathode connecting rod is connected to the cathode connection plate, and the anode connecting rod is connected to the anode connection plate.

[0022] Further, the solid-phase adsorption and capture CO2 device further includes a gasket located between the opening of the inner cavity and the cover plate. The gasket conforms to the shape of the opening of the inner cavity. One end is located on the cover plate, and the pressure sensor and the temperature sensor extend into the inner cavity through the cover plate and the gasket. Among them, the air inlet and the air outlet are communicated with the inner cavity through the gasket.

[0023] The third object of the present invention is to provide a method for solid-phase adsorption and capture of CO2. The solid-phase adsorption and capture CO2 device in the second object of the claims is used for CO2 capture, including the following steps:

[0024] Step 1: Blow the gas containing CO2 to be treated into the inner cavity of the solid-phase adsorption and capture CO2 device;

[0025] Step 2: Apply a capture voltage to cause the first redox carrier in the cathode layer to undergo a reduction reaction to capture CO2 in the gas;

[0026] Step 3: Apply a release voltage to cause the first redox carrier in the cathode layer to undergo an oxidation reaction to release the previously captured CO2.

[0027] Further, the capture voltage in Step 2 is not less than the potential difference between the reduction of the first redox carrier and the oxidation of the second redox carrier;

[0028] The release voltage in Step 3 is less than the potential difference between the reduction of the second redox carrier and the oxidation of the first redox carrier.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention realizes the solid-phase adsorption of carbon dioxide through an electrochemically mediated method, directly using electrical energy as the driving force, avoiding the problems of the large use of solvents and high-energy-consuming desorption in traditional methods. This innovation not only significantly reduces the cost of carbon capture but also effectively reduces solvent pollution, which is of positive significance to environmental protection. At the same time, the solid-phase adsorption CO₂ capture device in the present invention has characteristics such as being small and having a flexible layout, being highly suitable for different complex systems, and providing the possibility for the wide application of carbon capture technology. Thus, the present invention provides a simple and feasible electrochemically mediated carbon dioxide capture process, and through precise control of the charging and discharging potentials, precise regulation of the carbon dioxide capture and release processes is achieved.

[0031] 2. The solid-phase adsorption CO₂ capture electrode in the present invention is composed of electrode units with a sandwich structure. By setting the electrode units as a "cathode + anode + cathode" combination, it not only meets the function of the anode to balance charges but also expands the capture area, improves the carbon capture efficiency, and according to later tests, it is found that using the electrode in the present invention for CO₂ capture has lower energy consumption than the traditional liquid-phase absorption method. Brief Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the electrochemical capture and release of carbon dioxide in the present invention, where Figure 1 Figure (a) is a schematic diagram of carbon dioxide capture, and Figure (b) is a schematic diagram of carbon dioxide release;

[0033] Figure 2 It is a schematic structural diagram of the electrode unit in the present invention;

[0034] Figure 3 It is a three-dimensional structural diagram of the solid-phase adsorption CO₂ capture device in the present invention;

[0035] Figure 4 It is a top-view structural diagram of the solid-phase adsorption CO₂ capture device in the present invention;

[0036] Figure 5 It is a sectional structural diagram of the solid-phase adsorption CO₂ capture device in the present invention;

[0037] Figure 6 It is a sectional structural diagram of the solid-phase adsorption CO₂ capture device in the present invention;

[0038] Figure 7 It is a schematic structural diagram of the cathode connection plate in the present invention;

[0039] Figure 8 It is a schematic structural diagram of the anode connection plate in the present invention;

[0040] Figure 9This is the graph of the capture capacity, desorption amount, desorption rate, and desorption energy consumption for CO2 capture in the present invention;

[0041] Explanation of reference numerals:

[0042] 1. Solid-phase adsorption CO2 capture electrode, 1-1. Cathode layer, 1-2. Diaphragm, 1-3. Anode layer, 1-4. Electrolyte support layer, 1-5. Current collector; 2. Pressure sensor interface; 3. Temperature sensor interface; 4. Spare interface; 5. Inlet; 6. Outlet; 7. Inner cavity; 8. Gasket; 9. Outer shell; 10. Cover plate; 11. Cathode connection plate; 12. Anode connection plate; 13. Card slot; 14. Lock; 15. Cathode metal clip; 16. Cathode connection rod; 17. Anode connection rod; 18. Contact; 19. Top block. Detailed implementation manners

[0043] Next, a solid-phase adsorption CO2 capture electrode, device, and method in the present application will be described in combination with embodiments.

[0044] However, the present application can be exemplified in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0045] The inventor conducted a detailed investigation based on current CO2 capture technologies, especially the relatively emerging emission reduction means of electrochemically mediated carbon capture technology in recent years, and found that the currently widely studied electrochemically mediated carbon capture technologies include electrochemically mediated amine regeneration (EMAR) and electrochemically mediated pH swing, etc. For example, a system and method for capturing CO2 by electrochemically mediated amine regeneration are described in a patent with the patent number: CN202411302325.5. In this system, metal copper is used as the electrode and an organic amine solution is used as the absorbent. In this technology, during the absorption stage, the amine absorbent reacts with CO2 to form carbamate or bicarbonate, etc., to achieve the capture of carbon dioxide; during the release stage, the absorbent is regenerated by an electrochemical method, and at the same time, CO2 is released to complete the cycle of capture and release. The EMAR technology has mild operating conditions and good reversibility, but it involves multiple aspects such as the construction of the electrochemical system, the selection of the absorbent, and the control of reaction conditions. The system design and operation are relatively complex. In continuous absorption-desorption cycles, the amine absorbent may lose its activity due to degradation, resulting in a decrease in the capture efficiency.

[0046] For another example, the documents with patent numbers CN202311151852.6 and CN202410353357.1 record a method for capturing CO2 by using pH changes. The method is as follows: the pH value of the solution is changed through an electrochemical oxidation-reduction reaction, thereby realizing the capture and release of CO2; specifically, when the solution is in an alkaline state, the concentration of OH - ions increases, which is conducive to the absorption of CO2, forming carbonates or bicarbonates; when the solution is acidified, it promotes the decomposition of carbonates / bicarbonates, releasing CO2. This technology can adapt to carbon capture requirements of different scales and operate isothermally under environmental conditions, but there are also problems such as the use of organic adsorbents or inorganic solutions and the corrosion of the device.

[0047] As can be seen from the above, the existing electrochemically mediated carbon capture technologies generally still rely on the continuous operation of the liquid phase system, and the absorbent for capturing CO2 needs to be dissolved in a specific solvent to release CO2. It can be seen that these methods significantly increase the amount of electrolyte solution and solvent, resulting in a large overall floor area of the device. In addition, when these methods involve the operation of the system, not only is the energy consumption high, but the operation process is also complex. These factors together constitute the main challenges and limitations faced by the current electrochemically mediated carbon capture technology in practical applications.

[0048] Based on this, the present invention provides a solid-phase adsorption CO2 capture electrode, device and method with less solvent consumption, low energy consumption and convenient operation.

[0049] An embodiment of the first aspect of the present invention provides a solid-phase adsorption CO2 capture electrode. The solid-phase adsorption CO2 capture electrode includes an electrode unit. The electrode unit includes a cathode layer, the cathode layer has two layers, an anode layer located between the two cathode layers, a current collector located on the cathode layer and away from the anode layer side, and an electrolyte layer, a diaphragm and an electrolyte layer arranged in sequence between the anode layer and the cathode layer; wherein, the number of electrode units is at least 1; the cathode layer includes a carbon substrate and a conductive material loaded with a first redox carrier on the carbon substrate; the anode layer includes a carbon substrate and a conductive material loaded with a second redox carrier on the carbon substrate; the electrolyte layer includes a conductive layer and an electrolyte filled in the conductive layer.

[0050] In the present invention, the first redox carrier in the cathode layer undergoes a reduction reaction after applying an external voltage, and can undergo an electrophilic addition reaction with CO2 to achieve selective adsorption of low-concentration carbon dioxide (as shown in Figure 1 Figure (a) below); after applying a release voltage, the first redox carrier combined with CO2 undergoes an oxidation reaction, showing a repulsive effect on carbon dioxide, and realizing the desorption of carbon dioxide (as shown in Figure 1as shown in Figure (b) therein. It can be seen that in the present invention, the capture and release of CO2 both occur in the cathode layer. Therefore, in the present invention, the electrode unit constituting the solid-phase adsorption and capture CO2 electrode is set into a sandwich "cathode + anode + cathode" structure, which structure satisfies the charge balance of the anode layer, while expanding the capture area when the cathode layer captures CO2, and improving the carbon capture efficiency. In addition, it also avoids the need to adsorb CO2 in a solvent to form carbonate or bicarbonate in the prior art, thereby reducing the amount of solvent used, and also avoids the need to acidify the carbonate or bicarbonate when releasing CO2, and further avoids the problem of corrosion of the device caused by the acidification process.

[0051] In addition, the solid-phase adsorption and capture CO2 electrode in the present invention can be composed of one electrode unit, or can be composed of multiple electrode units. The electrode composed of multiple electrode units can further increase the CO2 capture ability of the electrode. In the following, the present invention will be described with the solid-phase adsorption and capture CO2 electrode composed of one electrode unit.

[0052] Secondly, the electrolyte layer of the present invention directly fills the electrolyte in the conductive layer. Therefore, only a small amount of electrolyte is required for the electrolysis reaction, reducing the amount of electrolyte used and to a certain extent reducing the volume of the CO2 capture device.

[0053] The preparation of the cathode layer in the present invention is as follows: First, a first redox carrier is loaded on a conductive material with a mass fraction of 10% to 50%, and the above-mentioned conductive material is uniformly coated on a carbon substrate to obtain the cathode layer. The preparation method of the anode layer is the same as that of the cathode layer, except that a second redox carrier is loaded on the conductive material, and the loading amount of the second redox carrier is 30 wt.% to 70 wt.%. Preferably, the oxidation potential value required for the first redox carrier to release CO2 is more negative than the potential value at which the second redox carrier undergoes a reduction reaction, so as to further ensure that the electrode can effectively capture and release CO2. Further preferably, the first redox carrier contains C=O or / and C=N groups; still further preferably, the first redox carrier is any one of monomers, polymers and their derivatives of quinone, pyridine, phenazine, and conductive metal-organic frameworks; the second redox carrier is any one of ferrocene, 1,1'-diethylferrocene, n-octylferrocene, polyvinylferrocene, lithium iron phosphate, lithium cobaltate, and lithium manganate; the conductive material is any one of graphene, carbon nanotubes, porous carbon, and conductive carbon black; the carbon substrate is carbon paper or carbon cloth; further preferably, the conductive material is multi-walled carbon nanotubes with a diameter of 5 - 15 nm, a length of 10 - 30 μm, and a specific surface area of 220 - 300 m 2 / g.

[0054] In addition, the solvent used for dispersion during the preparation of the cathode layer and the anode layer can be dimethyl sulfoxide, and in practice, it can also be other solvents with properties similar to dimethyl sulfoxide.

[0055] In this embodiment, the preparation of the electrolyte layer is as follows: The electrolyte is directly infiltrated (i.e., wetted) into the conductive layer to obtain the electrolyte layer in the present invention. Preferably, the conductive layer in this embodiment is a porous conductive material. Further preferably, the porous conductive material is carbon felt or carbon cloth. Of course, it can also be other materials with pores and conductivity. The electrolyte in this embodiment is any one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate, and ionic liquids; among them, the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]TF2N) or N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([P14]Tf2N).

[0056] In addition, in some embodiments, the separator in the present invention is a polymer. Preferably, the polymer is any one of a cellulose membrane, a glass fiber separator, a polyimide membrane, and a polyester membrane. The current collector is a metal mesh, and the mesh number of the metal mesh is 50 to 200; preferably, the current collector is a stainless steel mesh or a titanium mesh. Of course, in practice, it can also be a mesh made of other materials with similar properties.

[0057] Based on the above, the preparation of the solid-phase adsorption and capture CO2 electrode composed of one electrode unit in the present invention is as follows: The cathode layer, anode layer, and electrolyte layer prepared above are assembled in sequence according to the current collector, cathode layer, electrolyte layer, separator, electrolyte layer, anode layer, electrolyte layer, separator, electrolyte layer, cathode layer, and current collector to obtain the Figure 2 solid-phase adsorption and capture CO2 electrode as shown.

[0058] The reactions involved in the electrolysis of the cathode layer and anode layer in the present invention are described below using phenazine as the first redox carrier and ferrocene as the second redox carrier, as follows:

[0059] Reactions occurring in the cathode layer:

[0060]

[0061] Reactions occurring in the anode layer:

[0062]

[0063] As can be seen from the above formulas (1) and (2), the first redox carrier phenazine in the cathode layer undergoes a reduction reaction after the application of the capture voltage, shows an affinity for acidic carbon dioxide, and can undergo an electrophilic addition reaction with it to achieve selective adsorption of low-concentration carbon dioxide. After the application of the release voltage, the phenazine combined with CO2 undergoes an oxidation reaction, shows a repulsive effect on carbon dioxide, and realizes the desorption of carbon dioxide. The second redox carrier ferrocene in the anode layer undergoes an oxidation reaction after the application of the capture voltage and a reduction reaction after the application of the release voltage to balance the charge.

[0064] An embodiment of the second aspect of the present invention provides a solid-phase adsorption and capture CO2 device, which includes the solid-phase adsorption and capture CO2 electrode 1 provided in the embodiment of the first aspect, a housing 9, an inner cavity 7, a cover plate 10, a pressure sensor, a temperature sensor, an air inlet 5, an air outlet 6, an electrochemical capture circuit unit, a cathode connecting rod 16, and an anode connecting rod 17.

[0065] Specifically, as Figure 2 shown, the electrode unit in the solid-phase adsorption and capture CO2 electrode includes a current collector 1-5, a cathode layer 1-1, an electrolyte layer 1-4, a separator 1-2, and an anode layer 1-3, and they are sequentially arranged in the order of current collector, cathode layer, electrolyte layer, separator, electrolyte layer, anode layer, electrolyte layer, separator, electrolyte layer, cathode layer, and current collector.

[0066] The following takes the solid-phase adsorption and capture CO2 electrode consisting of one electrode unit as an example to elaborate in detail on the solid-phase adsorption and capture CO2 device in the present invention.

[0067] As Figures 3 to 8 shown, the solid-phase adsorption and capture CO2 device includes a housing 9 and a cover plate 10. The housing 9 and the cover plate 10 are connected by a buckle 14. At the same time, in order to ensure that the device can withstand a certain pressure, the housing and the cover plate in the present invention are made of stainless steel materials. Of course, in practice, other materials that can withstand a certain pressure can also be used. The inner cavity 7 is located in the housing 9, the inner cavity is in an open shape, and the cover plate 10 is located at the opening of the inner cavity 7. In addition, in order to further seal the inner cavity, a gasket 8 conforming to the opening shape of the inner cavity is provided at the opening of the inner cavity. The inner cavity and the cover plate are further sealed under the action of the gasket 8. In addition, in order to avoid electrochemical interference when the solid-phase adsorption and capture CO2 device in the present invention captures CO2 by energization, the inner cavity and the gasket are made of insulating materials, such as polytetrafluoroethylene or polypropylene.

[0068] In order to facilitate the replacement of the inner cavity, so as to meet the requirements for capturing CO2 of different scales, as Figures 4 to 5As shown, a top block 19 is provided below the outer bottom wall of the inner cavity 7. One end of the top block 19 is in contact with the outer bottom wall of the inner cavity, and the other end is in contact with the inner bottom wall of the outer shell 9. When replacing the inner cavity 7, the top block 19 can push out the inner cavity to facilitate the replacement of the inner cavity. In addition, an O-ring seal (not shown in the drawings) is also provided between the base and the outer shell.

[0069] As Figures 3 to 8 shown, a pressure sensor interface 2 for placing a pressure sensor and a temperature sensor interface 3 for placing a temperature sensor are provided on the cover plate 10. The pressure sensor interface 2 and the temperature sensor interface 3 both penetrate through the cover plate 10. The pressure sensor and the temperature sensor respectively pass through the pressure sensor interface 2 and the temperature sensor interface 3 and then penetrate through the gasket 8 to extend into the inner cavity 7 (the pressure sensor and the temperature sensor are not shown in the drawings). Among them, the pressure sensor is mainly used to monitor the dynamic changes of the pressure inside the inner cavity before and after capturing CO2, and calculate the capture capacity of the solid-phase adsorption CO2 capture electrode for CO2 through the gas state equation. The temperature sensor is used to synchronously record the temperature change of the inner cavity during the capture process. In addition, the present invention also has a spare port 4, which serves as a spare interface for the pressure sensor interface and the temperature sensor interface.

[0070] As Figures 3 to 8 shown, one end of the cathode connecting rod 16 and the anode connecting rod 17 penetrates through the cover plate and is connected to the electrochemical capture circuit unit, and the other end is connected to the power supply, so as to connect the device to an external power supply.

[0071] As Figures 3 to 8 shown, the electrochemical capture circuit unit includes a cathode connection plate 11, an anode connection plate 12, a card slot 13, and a cathode metal clip 15. Specifically, the cathode connection plate 11 and the anode connection plate 12 are both located in the inner cavity 7 and are symmetrically positioned. Card slots 13 are provided on both the cathode connection plate and the anode connection plate, and the card slots are used to install the solid-phase adsorption CO2 capture electrode. The cathode metal clip 15 is arranged on the card slot 13 located on the cathode connection plate 11. Among them, the cathode connection rod 16 is connected to the cathode connection plate 11, and the anode connection rod 17 is connected to the anode connection plate 12. In the present invention, when the solid-phase adsorption CO2 capture electrode is inserted into the card slot, the cathode layer is in contact with the cathode metal clip to achieve connection with the cathode connection plate 11, and the anode layer is connected to the anode connection plate through a wire. In addition, in the present invention, the number of card slots on the cathode connection plate and the anode connection plate is multiple. As Figure 7 and 8 shown, it can be 5. Of course, in practice, the number of card slots can be increased according to the amount of CO2 in the gas to be captured, and then the number of solid-phase adsorption CO2 capture electrodes can be increased, thereby increasing the area of the cathode layer and expanding the CO2 capture capacity of the device. In addition, when installing multiple solid-phase adsorption CO2 capture electrodes on the cathode connection plate and the anode connection plate, the solid-phase adsorption CO2 capture electrodes are connected in parallel to the circuit.

[0072] In addition, in the present invention, contacts 18 are provided on both the cathode connection plate 11 and the anode connection plate 12, and the cathode connecting rod 16 and the anode connecting rod 17 are respectively connected to the cathode connection plate 11 and the anode connection plate 12 through the contacts 18. That is, in the present invention, the cathode connection plate and the anode connection plate are respectively connected to the power supply through the cathode connection rod 16 and the anode connection rod 17.

[0073] As Figures 3 to 6 shown, the air inlet 5 and the air outlet 6 are located on the cover plate 10, the air inlet 5 and the air outlet 6 penetrate through the cover plate, and the gasket 8 is provided with holes for the air inlet 5 and the air outlet 6 to communicate with the inner cavity 7.

[0074] An embodiment of the third aspect of the present invention provides a method for CO2 capture based on the solid-phase adsorption and capture CO2 electrode of the first aspect and the solid-phase adsorption and capture CO2 device of the second aspect. The method includes the following steps:

[0075] Step 1: After purging the CO2-containing gas to be processed into the inner cavity, seal it; preferably, stop sweeping the CO2-containing gas into the inner cavity until the pressure in the inner cavity is stable under constant temperature conditions.

[0076] Step 2: Apply a capture voltage to the solid-phase adsorption and capture CO2 device through the power supply to cause a reduction reaction of the first redox carrier in the cathode layer, thereby achieving the capture of CO2; preferably, maintain this voltage state until the pressure in the inner cavity no longer changes, which indicates that the CO2 adsorption reaches equilibrium.

[0077] Step 3: Apply a release voltage to the device through the power supply to cause an oxidation reaction of the first redox carrier in the cathode, thereby releasing the previously captured CO2.

[0078] In the present invention, the carbon dioxide capture capacity corresponding to the solid-phase adsorption and capture CO2 electrode can be calculated according to the gas state equation where P1 and T1 are respectively the pressure and temperature of the inner cavity after the pressure in the inner cavity in Step 1 is stable under constant temperature conditions, and P2 and T2 are respectively the pressure and temperature of the inner cavity when the pressure in the inner cavity in Step 2 no longer changes.

[0079] In addition, in some embodiments, the capture voltage in Step 2 is not less than the potential difference between the reduction of the first redox carrier and the oxidation of the second redox carrier. For example, the range of the capture voltage can be 1.2 - 1.8V; the release voltage in Step 3 is less than the potential difference between the reduction of the second redox carrier and the oxidation of the first redox carrier. For example, the range of the capture voltage can be 0.6 - 1.0V. In this embodiment, the capture voltage and the release voltage are not limited to the given examples, and the voltage range values can change according to the differences between the first redox carrier and the second redox carrier.

[0080] Example

[0081] The following is a specific example to illustrate in detail the solid-phase adsorption and capture CO2 electrode (the solid-phase adsorption and capture CO2 electrode consists of one electrode unit) and the method for solid-phase adsorption and capture of CO2 in the present invention, as follows:

[0082] Example 1

[0083] I. Preparation of the solid-phase adsorption and capture CO2 electrode, including the following steps:

[0084] Step 1. Preparation of the cathode layer (PhN-CNT / CP): Dissolve phenazine and multi-walled carbon nanotubes (the selected multi-walled carbon nanotubes have a diameter of 5 - 15 nm, a length of 10 - 30 μm, and a specific surface area of 220 - 300 m 2 / g) in a dimethyl sulfoxide (DMSO) solvent at a mass ratio of 1:1, and obtain a uniform ink by ultrasonic dispersion. Subsequently, uniformly drop the ink on the carbon paper (the area of the carbon paper is 2.5×4 cm 2 ) and dry it at 120°C for 60 min. Continue to drop the ink on the carbon paper and dry it at 120°C for 60 min. Then continue to drop the ink on the carbon paper and dry it at 120°C for 10 h. Finally, obtain the PhN-CNT / CP cathode layer;

[0085] Step 2. Preparation of the anode layer (Fc-CNT / CP): Dissolve ferrocene and multi-walled carbon nanotubes (the multi-walled carbon nanotubes have a diameter of 5 - 15 nm, a length of 10 - 30 μm, and a specific surface area of 220 - 300 m 2 / g) in a dimethyl sulfoxide solvent at a mass ratio of 2:1, and then ultrasonically disperse it into a uniform ink. Subsequently, uniformly drop the ink on the carbon paper (the area of the carbon paper is 2.5×3.5 cm 2 ) and dry it at 120°C for 60 min. Continue to drop the ink on the carbon paper and dry it at 120°C for 60 min. Then continue to drop the ink on the carbon paper and dry it at 120°C for 10 h. After drying, obtain the Fc-CNT / CP anode layer;

[0086] Step 3. Preparation of the electrolyte layer: Uniformly moisten 500 uL of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]TF2N) on the carbon felt with an area of 2.5×4 cm 2 to obtain the electrolyte.

[0087] Step 4: Preparation of the solid-phase adsorption and capture CO₂ electrode: The solid-phase adsorption and capture CO₂ electrode is obtained by pressing and assembling layers in the order of current collector, PhN-CNT / CP cathode layer, electrolyte layer, separator, electrolyte layer, Fc-CNT / CP anode layer, electrolyte layer, separator, electrolyte layer, PhN-CNT / CP cathode layer, and current collector; wherein, the separator is made of cellulose membrane, and the current collector is made of 100-mesh stainless steel mesh.

[0088] II. Solid-phase adsorption and capture CO₂ device

[0089] According to the description of the solid-phase adsorption and capture CO₂ device above, install the solid-phase adsorption and capture CO₂ electrode prepared in "I" in the card slot, and install a total of 5 solid-phase adsorption and capture CO₂ electrodes. At the same time, connect the circuit and gas path to ensure good airtightness.

[0090] III. Method for solid-phase adsorption and capture of CO₂, including the following steps:

[0091] Step 1: Fill the inner cavity of the solid-phase adsorption and capture CO₂ device with air until the pressure stabilizes at 110 kPa, and record the initial pressure P1 and temperature T1.

[0092] Step 2: Apply a capture voltage of 1.7 V to the solid-phase adsorption and capture CO₂ device to oxidize ferrocene and reduce phenazine until the pressure stabilizes. Record the final temperature T2 and pressure P2, and use the ideal gas state equation to calculate the capture capacity.

[0093] Step 3: Apply a release voltage of 0.7 V to the solid-phase adsorption and capture CO₂ device to reduce ferrocene and oxidize phenazine, and release the captured CO₂.

[0094] After testing, after filling with air, the solid-phase adsorption and capture CO₂ device in this embodiment has a CO₂ capture capacity of 5.98 mol·kg -1 under a capture voltage of 1.7 V, and the CO₂ desorption amount under a release voltage of 0.7 V is 4.32 mol·kg -1 , the desorption rate is 72.24%, and the desorption energy consumption is 2.95 GJ / t CO₂.

[0095] Example 2

[0096] In this example, the preparation of the solid-phase adsorption and capture CO₂ electrode is the same as that in Example 1 above, and the solid-phase adsorption and capture CO₂ device is the same. The difference is that when capturing CO₂, the gas filled into the inner cavity of the solid-phase adsorption and capture CO₂ device is simulated flue gas (the simulated flue gas is composed of 15 vol% CO₂ and 85 vol% N₂).

[0097] After testing, after filling with flue gas, the solid-phase CO2 adsorption device in this embodiment has a CO2 capture capacity of 7.31 mol·kg at a capture voltage of 1.7 V. -1 The CO2 desorption amount at a release voltage of 0.7 V is 5.94 mol·kg -1 , the desorption rate is 81.25%, and the desorption energy consumption is 2.43 GJ / t CO2.

[0098] Comparative Example 1

[0099] In this embodiment, traditional MEA (ethanolamine) solvent is used to absorb and capture CO2, and its absorption capacity and regeneration energy consumption are tested.

[0100] Absorption conditions: The absorbent is 30 wt.% MEA, the solvent volume is 50 mL, the CO2 concentration is 15 ± 0.05%, the total gas flow rate is 500 mL / min, the basis for judging absorption saturation is 15 ± 0.1%, and the absorption temperature is 40 °C.

[0101] Desorption conditions: The volume of the rich liquid is 20 mL, the N2 gas flow rate is 200 mL / min, the basis for judging complete desorption is that the CO2 vol.% in the MEA solution ≤ 0.25%, the target desorption temperature deviation is ±1 °C, and the desorption temperature is 100 °C.

[0102] The steps of the absorption process are as follows: (1) Purge the entire experimental system with N2 to ensure that there is no CO2 residue in the system; (2) Add 50 mL of absorbent to the three-necked flask, and use a constant temperature water bath to control the absorption temperature at 303 - 323 K, and the thermometer monitors the absorbent temperature in real time; (3) CO2 and N2 from the gas cylinders are controlled by a mass flow meter, and after passing through the mixing tank, a uniform 15 ± 0.05 vol.% CO2 mixed gas (425 mL / min N2) is formed to simulate industrial flue gas, and the mixed gas is bubbled into the three-necked flask to react with the absorbent. During the process, magnetic stirring is used to enhance gas-liquid mass transfer; (4) The reacted gas is condensed by a cooling medium at -5 °C, then passed through a washing bottle filled with concentrated sulfuric acid and a drying tube filled with cotton, and then passed into a CO2 infrared analyzer for on-line detection of the CO2 concentration. When the outlet concentration reaches 15 ± 0.2 vol.% and remains unchanged for 10 min, it is considered absorption saturation.

[0103] The CO2 absorption capacity is measured by acid titration method, the constant pressure specific heat capacity of the MEA solvent is measured by differential scanning calorimetry, and the absorption reaction heat is measured by thermogravimetric analyzer.

[0104] After testing, the saturated CO2 loading of 30 wt.% MEA solvent titrated in this embodiment at 40 °C is 2.81 mol·kg -1 , the CO2 desorption amount at 100 °C is 2.22 mol·kg -1, the desorption rate is 78.79%, and the desorption energy consumption is 4.30 GJ / t CO2.

[0105] From Example 1, Example 2 and Comparative Example 1, and Figure 9 it can be seen that when using the device of the solid-phase adsorption and capture CO2 electrode in the present invention for CO2 capture, it has the advantages of high capture capacity, large desorption amount and low capture energy consumption (see details in Figure 9 ).

[0106] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A solid-phase adsorption and capture CO2 electrode, characterized in that, It includes an electrode unit, the electrode unit includes a cathode layer, the cathode layer is two layers, an anode layer located between the two cathode layers, a current collector located on the cathode layer and on the side far from the anode layer, and an electrolyte layer, a separator and an electrolyte layer which are sequentially arranged between the anode layer and the cathode layer; wherein, the number of electrode units is at least 1; The cathode layer includes a carbon substrate and a conductive material located on the carbon substrate and loaded with a first redox carrier; The anode layer includes a carbon substrate and a conductive material located on the carbon substrate and loaded with a second redox carrier; The electrolyte layer includes a conductive layer and an electrolyte filled in the conductive layer.

2. The solid-phase adsorption and capture CO2 electrode according to claim 1, wherein The oxidation potential value required for the first redox carrier to release CO2 is more negative than the potential value at which the second redox carrier undergoes a reduction reaction.

3. The solid-phase adsorption and capture CO2 electrode according to claim 2, wherein The first redox carrier contains C=O or / and C=N groups.

4. The solid-phase adsorption and capture CO2 electrode according to claim 3, wherein The first redox carrier is any one of quinone, pyridine, phenazine monomers, polymers and their derivatives, and conductive metal-organic frameworks; The second redox carrier is any one of ferrocene, 1,1'-diethylferrocene, n-octylferrocene, polyvinylferrocene, lithium iron phosphate, lithium cobaltate and lithium manganate; The conductive material is any one of graphene, carbon nanotubes, porous carbon and conductive carbon black; The carbon substrate is carbon paper or carbon cloth.

5. The solid-phase adsorption and capture CO2 electrode according to claim 1, wherein The conductive layer is a porous conductive material, and the electrolyte is any one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, lithium tetrafluoroborate and ionic liquid; The separator is a polymer; The current collector is a metal mesh, and the mesh number of the metal mesh is 50-200.

6. A solid-phase adsorption and capture CO2 device, characterized in that, It includes a housing, an inner cavity which is open and located inside the housing, a cover plate connected to the housing and located at the opening of the inner cavity, an air inlet and an air outlet which penetrate through the cover plate and are communicated with the inner cavity, an electrochemical capture circuit unit located in the inner cavity, a solid-phase adsorption and capture CO2 electrode according to any one of claims 1-5 mounted on the electrochemical capture circuit unit, and a cathode connecting rod and an anode connecting rod which penetrate through the cover plate at one end and are both connected to the electrochemical capture circuit unit.

7. The solid-phase adsorption and capture CO2 device according to claim 6, wherein The electrochemical capture circuit unit includes a cathode connection plate and an anode connection plate which are symmetrically located in the inner cavity, and card slots for mounting the solid-phase adsorption and capture CO2 electrode are provided on both the cathode connection plate and the anode connection plate. Cathode metal clips are provided on the card slots on the cathode connection plate. Among them, the cathode layer is connected to the cathode connection plate through the cathode metal clips, the anode layer is connected to the anode connection plate through a wire, the cathode connecting rod is connected to the cathode connection plate, and the anode connecting rod is connected to the anode connection plate.

8. The solid-phase adsorption and capture CO2 device according to claim 6, wherein The solid-phase adsorption and capture CO2 device further includes a gasket located between the opening of the inner cavity and the cover plate. The gasket conforms to the shape of the opening of the inner cavity. A pressure sensor and a temperature sensor are located at one end on the cover plate and the other end extends into the inner cavity through the cover plate and the gasket. Among them, the air inlet and the air outlet are communicated with the inner cavity through the gasket.

9. A method for solid-phase adsorption and capture of CO2, characterized in that, Performing CO2 capture using the solid-phase adsorption CO2 capture device according to any one of claims 6 to 8, comprising the following steps: Step 1: Blowing the gas containing CO2 to be treated into the inner cavity of the solid-phase adsorption CO2 capture device; Step 2: Applying a capture voltage to cause the first redox carrier in the cathode layer to undergo a reduction reaction to capture CO2 in the gas; Step 3: Applying a release voltage to cause the first redox carrier in the cathode layer to undergo an oxidation reaction to release the previously captured CO2.

10. The method according to claim 9, wherein The capture voltage in Step 2 is not less than the potential difference between the reduction of the first redox carrier and the oxidation of the second redox carrier; The release voltage in Step 3 is less than the potential difference between the reduction of the second redox carrier and the oxidation of the first redox carrier.

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