Method and system for producing formate through synergistic trapping and conversion of flue gas carbon dioxide

Abstract

The invention relates to the field of carbon dioxide capture and utilization, in particular to a method and system for producing formate through synergistic capture and conversion of flue gas carbon dioxide, formate is obtained through electrochemical conversion of carbon-rich capture liquid, capture liquid is generated, the capture liquid directly captures flue gas carbon dioxide, and the carbon-rich capture liquid is obtained again. And the carbon-rich trapping liquid is continuously recycled for electrochemical conversion. The carbon-rich capture liquid electrochemical conversion process and the flue gas carbon dioxide capture process do not need to be alternately carried out step by step, but are synchronously and continuously carried out in the same system, the whole process does not need to pre-treat a small amount of oxygen and trace nitrogen oxide and sulfur oxide gas impurities in the flue gas, and a high-energy-consumption carbon dioxide gas regeneration step is avoided; the method overcomes the defect of low single conversion rate of electrochemical conversion of carbon dioxide gas, realizes collaborative capture and conversion of flue gas carbon dioxide to produce formate, and finally realizes direct conversion and utilization of carbon dioxide from flue gas to a high-value product formate.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture and utilization, and particularly to a method and system for synergistically capturing and converting flue gas carbon dioxide to produce formate. Background Art

[0002] The excessive emission of carbon dioxide has led to a series of environmental problems such as global warming, ocean acidification, and land desertification, which have attracted great attention and emphasis globally. Developing carbon dioxide capture and electrochemical conversion to obtain high-value fuels and chemicals is an important technology for reducing carbon emissions and promoting carbon resource utilization. As the main carbon dioxide emission source, flue gas usually contains varying concentrations (5%-15%) of oxygen and trace amounts of nitrogen oxides and sulfur oxide gas impurities. These gases will seriously interfere with the electrochemical conversion of carbon dioxide, making the carbon dioxide in the flue gas unable to be directly utilized and requiring the removal of these gas impurities first. Therefore, traditional carbon dioxide electrochemical conversion technologies require the use of high-purity carbon dioxide gas. However, pure carbon dioxide gas usually needs to be obtained through high-energy-consuming steps such as high-temperature desorption, purification, and compression from carbon-rich capture liquid, and the single-pass conversion rate of carbon dioxide in traditional carbon dioxide electrochemical conversion technologies is relatively low. Therefore, the current entire carbon capture and electrochemical utilization process has the disadvantages of multiple links, high energy consumption, and low efficiency.

[0003] Recently, researchers have begun to attempt to bypass the high-energy-consuming carbon dioxide desorption step and directly perform electrochemical conversion on the carbon-rich capture liquid to obtain valuable chemicals. Although the method of directly performing electrochemical conversion on the carbon-rich capture liquid overcomes the disadvantages of traditional carbon dioxide electrochemical conversion, it still maintains the order of independent operation of first capture and then conversion. First, the capture liquid reacts with carbon dioxide to obtain the carbon-rich capture liquid, and then the above carbon-rich capture liquid is collected and electrochemically converted under an inert atmosphere to obtain the target product while regenerating the capture liquid. The regenerated capture liquid needs to be collected again and re-supplied to the carbon dioxide capture module. The above capture and conversion processes are independently operated in their respective modules, and do not truly integrate carbon dioxide capture and conversion into a completely synchronous and continuous operation system. In addition, the carbon utilization rate in the conversion stage of the above relatively independent integrated system is relatively high. However, compared with the amount of carbon dioxide input into the integrated system in the initial capture stage and the amount of target product finally converted, the carbon utilization rate is also not ideal, usually less than 20%.

[0004] Therefore, the above carbon dioxide capture and electrochemical conversion systems operating independently need to be further optimized and improved. Summary of the Invention

[0005] To solve the above technical problems, the object of the present invention is to provide a method and system for the co-capture and conversion of flue gas carbon dioxide to produce formate. The entire process does not require pretreatment of a small amount of oxygen, trace nitrogen oxides, sulfur oxides and other gas impurities in the flue gas. The carbon dioxide capture and electrochemical conversion processes do not need to be carried out step by step alternately, but are continuously and synchronously operated in the same system, bypassing the high-energy-consuming carbon dioxide gas regeneration step, overcoming the deficiency of low single-pass conversion rate of electrochemical conversion of gaseous carbon dioxide, and realizing the direct conversion and utilization of carbon dioxide from flue gas to high-value product formate.

[0006] To achieve the above object, the present invention is realized by the following technical solutions:

[0007] In the first aspect of the present invention, a method for the co-capture and conversion of flue gas carbon dioxide to produce formate is provided, specifically as follows:

[0008] Taking the bicarbonate solution or carbamate solution in the carbon dioxide capture tank as the initial cathode electrolyte for electrocatalytic conversion to produce formate, and generating the capture liquid simultaneously during the electrolysis process; the obtained capture liquid is immediately transported to the carbon dioxide capture tank for capturing flue gas carbon dioxide to obtain a carbon-rich capture liquid, and at the same time, it continues to be supplied to the cathode chamber of the electrolytic cell for electrochemical conversion to produce formate; the electrochemical conversion process and the flue gas carbon dioxide capture process occur continuously and synchronously in the same closed system, realizing the co-capture and electrochemical conversion of flue gas carbon dioxide.

[0009] Preferably, the concentration of the bicarbonate solution or carbamate solution in the initial cathode electrolyte (carbon-rich capture liquid) is 0.1 - 5 mol / L.

[0010] Preferably, the main components of the capture liquid are hydroxides, carbonates or amino-containing compounds.

[0011] More preferably, the carbonates include potassium carbonate, sodium carbonate, lithium carbonate and cesium carbonate;

[0012] The hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide and cesium hydroxide;

[0013] The amino group-containing compounds include amino acid compounds and organic amine compounds; further preferably, the amino group-containing compounds include sodium glycinate, potassium glycinate, lithium glycinate, cesium glycinate, sodium prolinate, potassium prolinate, lithium prolinate, cesium prolinate, sodium lysinate, potassium lysinate, lithium lysinate, cesium lysinate, sodium glutamate, potassium glutamate, lithium glutamate, cesium glutamate, sodium sarcosinate, potassium sarcosinate, lithium sarcosinate, cesium sarcosinate, sodium alaninate, potassium alaninate, lithium alaninate, cesium alaninate, sodium arginate, potassium arginate, lithium arginate, cesium arginate, sodium threoninate, potassium threoninate, lithium threoninate, cesium threoninate, sodium valinate, potassium valinate, lithium valinate, cesium valinate, sodium histidinate, potassium histidinate, lithium histidinate, cesium histidinate, monoethanolamine, diethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(butylamino)ethanol, N,N-dimethylethanolamine, methyldiethanolamine, diglycolamine, diisopropanolamine, methylaminoethanol, 2-ethylaminoethanol, hydroxyethyl ethylenediamine, piperazine, N-aminoethylpiperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

[0014] Preferably, in the method for synergistically capturing and converting flue gas carbon dioxide to produce formate, the process of electrochemically converting the carbon-rich capture liquid to produce formate is achieved through the following reactions (1) and (2):

[0015]

[0016] CO2 + H2O + 2e - →HCOO - + OH - (2)

[0017] In the method, the carbon dioxide capture process is achieved through the following reactions (3) and (4):

[0018]

[0019] Meanwhile, the following reaction (5) occurs at the anode:

[0020]

[0021] In the second aspect of the present invention, a system for synergistically capturing and converting flue gas carbon dioxide to produce formate is provided, including: a carbon dioxide synergistic capture and conversion module and an anodic side reaction module; the carbon dioxide synergistic capture and conversion module includes a cathode assembly and a carbon dioxide capture tank, the cathode assembly includes an electrolytic cell cathode chamber and a pump; the anodic side reaction module includes an electrolytic cell anode chamber; the electrolytic cell cathode chamber and the electrolytic cell anode chamber are separated by an ion exchange membrane.

[0022] Preferably, the liquid outlet end of the cathode chamber of the electrolytic cell is connected to the liquid inlet end of the pump, the liquid outlet end of the pump is connected to the liquid inlet end of the carbon dioxide capture tank, and the liquid outlet end of the carbon dioxide capture tank is connected to the liquid inlet end of the cathode chamber of the electrolytic cell; the gas inlet of the carbon dioxide capture tank is connected to the flue gas source.

[0023] Preferably, the ion exchange membrane is selected from one of bipolar membranes, cation exchange membranes, and anion exchange membranes, and is used to separate the cathode chamber and the anode chamber and conduct ion transport.

[0024] Preferably, the cathode chamber of the electrolytic cell is used to electrochemically convert the carbon-rich capture liquid to obtain the target product formate and generate the capture liquid, and the anode chamber of the electrolytic cell is used to electrochemically convert the anode electrolyte to generate oxygen.

[0025] More preferably, the electrolyte in the anode chamber of the electrolytic cell is potassium hydroxide solution with a concentration of 0.5 - 5 mol / L.

[0026] More preferably, the electrochemical conversion process uses electricity from various sources, including intermittent renewable clean energy that is not easy to store, which helps the utilization and storage of renewable but intermittent energy.

[0027] Preferably, the anode material used in the anode chamber of the electrolytic cell is nickel foam, platinum mesh or titanium mesh, preferably titanium mesh coated with iridium oxide, and the cathode catalyst used in the cathode chamber of the electrolytic cell is metals such as indium, tin, lead, bismuth and cobalt and their oxide / sulfide materials, preferably bismuth oxide catalyst.

[0028] The beneficial effects obtained by one or more of the above technical solutions of the present invention are as follows:

[0029] (1) In the system for synergistic capture and conversion of flue gas carbon dioxide to produce formate provided by the present invention, a carbon dioxide synergistic capture and conversion module and an anodic side reaction module are provided. The initial cathode electrolyte (carbon-rich capture liquid) is electrochemically converted to obtain formate and generate the capture liquid. The capture liquid is used to directly capture carbon dioxide in the flue gas to re-obtain the carbon-rich capture liquid, and at the same time, the carbon-rich capture liquid continues to be used for electrochemical conversion to produce formate. The above electrochemical conversion process of the carbon-rich capture liquid and the flue gas carbon dioxide capture process do not need to be carried out step by step alternately, but are synchronously and continuously carried out in the same system, that is, the synergistic capture and conversion of flue gas carbon dioxide is realized.

[0030] (2) The method for synergistic capture and conversion of flue gas carbon dioxide to produce formate adopted by the present invention does not need to pre-treat a small amount of oxygen and trace gas impurities such as nitrogen oxides and sulfur oxides in the flue gas, and can directly capture and electrochemically convert carbon dioxide in the flue gas, realizing the direct conversion and utilization of carbon dioxide from flue gas to high-value product formate.

[0031] (3) The method for co-capturing and converting flue gas carbon dioxide to produce formate provided by the present invention can flexibly utilize various sources of electricity, including intermittent renewable clean energy that is not easy to store, which helps the utilization and storage of renewable but intermittent energy. Description of the Drawings

[0032] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0033] Figure 1 Schematic diagram of the system for co-capturing and converting flue gas carbon dioxide to produce formate of the present invention;

[0034] Figure 2 For Example 2 of the present invention at 100 mA / cm 2 1H nuclear magnetic resonance spectrum of the potassium bicarbonate solution electrolyzed for 30 minutes to produce formate by continuously introducing simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, and a flow rate of 10 sccm) at a current density;

[0035] Figure 3 For Example 2 of the present invention at 100 mA / cm 2 Faraday efficiency of the potassium bicarbonate solution electrolyzed for 30 minutes to produce formate by continuously introducing simulated flue gas with different components (15% carbon dioxide, 80% nitrogen, 5% oxygen; 15% carbon dioxide, 85% nitrogen, and 200 ppm SO2; 15% carbon dioxide, 85% nitrogen, and 200 ppm NO, with a flow rate of 10 sccm) at a current density;

[0036] Figure 4 For Example 3 of the present invention at 100 mA / cm 2 Trend of the carbon dioxide capture utilization rate of the potassium bicarbonate solution electrolyzed for 24 hours by continuously introducing simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, and a flow rate of 10 sccm) at a current density;

[0037] Figure 5 For Example 3 of the present invention at 100 mA / cm 2 Faraday efficiency of the potassium bicarbonate solution electrolyzed for 24 hours to produce formate by continuously introducing simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, and a flow rate of 10 sccm) at a current density;

[0038] In the figure: 1. Cathode chamber of the electrolytic cell; 2. Pump; 3. Carbon dioxide capture tank; 4. Ion exchange membrane; 5. Anode chamber of the electrolytic cell. Detailed Embodiments

[0039] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0040] Example 1

[0041] In a typical implementation manner of the present invention, a system for synergistic capture and conversion of flue gas carbon dioxide to produce formate is proposed. As Figure 1 shown, it includes a carbon dioxide synergistic capture and conversion module and an anodic side reaction module; the carbon dioxide synergistic capture and conversion module includes a cathode assembly and a carbon dioxide capture tank 3, the cathode assembly includes an electrolytic cell cathode chamber 1 and a pump 2; the anodic side reaction module includes an electrolytic cell anode chamber 5; the electrolytic cell cathode chamber 1 and the electrolytic cell anode chamber 5 are separated by an ion exchange membrane 4.

[0042] Among them, the liquid outlet end of the electrolytic cell cathode chamber is connected to the liquid inlet end of the pump, the liquid outlet end of the pump is connected to the liquid inlet end of the carbon dioxide capture tank, the liquid outlet end of the carbon dioxide capture tank is connected to the liquid inlet end of the electrolytic cell cathode chamber, and the gas inlet of the carbon dioxide capture tank is connected to the flue gas source.

[0043] Specifically, the pump 2 is used to provide power for the liquid transportation of the carbon-rich capture liquid and the capture liquid in the closed pipeline of the electrolytic cell cathode chamber 1 - carbon dioxide capture tank 3 - electrolytic cell cathode chamber 1.

[0044] Specifically, the electrolytic cell cathode chamber 1 is used for the electrochemical conversion of the carbon-rich capture liquid, the electrolytic cell anode chamber 5 is used for the electrolysis of the anolyte, and the carbon dioxide capture tank 3 is a place for capturing flue gas carbon dioxide. Among them, the initial solution inside the carbon dioxide capture tank is a carbamate solution or a bicarbonate solution, and this solution does not react with carbon dioxide.

[0045] In this embodiment, the solvent used for the initial electrolyte in the electrolytic cell cathode chamber 1 is bicarbonate or carbamate, and the main components of the electrolytic products include hydroxides, carbonates, and amino-containing compounds; the hydroxides, carbonates, and amino-containing compounds are carbon dioxide absorbents.

[0046] Among them, the hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide, and cesium hydroxide; the carbonates include potassium carbonate, sodium carbonate, lithium carbonate, and cesium carbonate; the amino group-containing compounds include sodium glycinate, potassium glycinate, lithium glycinate, cesium glycinate, sodium prolinate, potassium prolinate, lithium prolinate, cesium prolinate, sodium lysinate, potassium lysinate, lithium lysinate, cesium lysinate, sodium glutamate, potassium glutamate, lithium glutamate, cesium glutamate, sodium sarcosinate, potassium sarcosinate, lithium sarcosinate, cesium sarcosinate, sodium alaninate, potassium alaninate, lithium alaninate, cesium alaninate, sodium arginate, potassium arginate, lithium arginate, cesium arginate, sodium threonate, potassium threonate, lithium threonate, cesium threonate, sodium valinate, potassium valinate, lithium valinate, cesium valinate, sodium histidinate, potassium histidinate, lithium histidinate, cesium histidinate, monoethanolamine, diethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(butylamino)ethanol, N,N-dimethylethanolamine, methyldiethanolamine, diglycolamine, diisopropanolamine, methylaminoethanol, 2-ethylaminoethanol, hydroxyethyl ethylenediamine, piperazine, N-aminoethylpiperazine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, etc.

[0047] Furthermore, the concentration ranges of the bicarbonate solution and the carbamate solution in the initial cathode electrolyte (carbon-rich capture liquid) are 0.1 - 5 mol / L, and the specific values of the concentration can be any value within this range.

[0048] In this embodiment, the cathode chamber 1 of the electrolytic cell is separated from the anode chamber 5 of the electrolytic cell by a bipolar membrane, a cation exchange membrane, or an anion exchange membrane.

[0049] In this embodiment, the cathode catalyst used in the cathode chamber can be metals such as indium, tin, lead, bismuth, and cobalt and their oxide / sulfide materials; the anode material used in the anode chamber can be nickel foam, platinum mesh, or titanium mesh.

[0050] In this embodiment, the electrochemical conversion process can flexibly utilize electric power from various sources, including intermittent renewable clean energy that is not easy to store, which helps the utilization and storage of renewable but intermittent energy.

[0051] In this embodiment, the electrolytic cell used in the electrochemical conversion process is a membrane electrode electrolytic cell.

[0052] The working principle of the system for synergistic capture and conversion of flue gas carbon dioxide to produce formate provided in this embodiment is as follows:

[0053] In the cathode chamber 1 of the electrolytic cell, the initial cathode electrolyte (carbon-rich capture liquid) is electrochemically converted to obtain formate and the capture liquid is generated. The capture liquid is circulated to the carbon dioxide capture tank 3 to directly capture the flue gas carbon dioxide and re-obtain the carbon-rich capture liquid. The carbon-rich capture liquid is continuously supplied to the cathode chamber 3 of the electrolytic cell under the action of the pump 2 for electrochemical conversion. The above process runs continuously in a cycle, continuously electrolyzing to obtain the target product formate while continuously capturing the flue gas carbon dioxide.

[0054] Meanwhile, during the electrolysis process, an oxygen evolution reaction occurs in the anode chamber 5 of the electrolytic cell to generate oxygen.

[0055] In the carbon dioxide co-capture and conversion module and the anodic side reaction module of the present invention, the target product formate is obtained by electrochemically converting the carbon-rich capture liquid and the capture liquid is generated. The capture liquid directly captures the carbon dioxide in the flue gas containing gas impurities and re-obtains the carbon-rich capture liquid. The above carbon-rich capture liquid electrochemical conversion process and the flue gas carbon dioxide capture process both occur in the same continuous system. The electrochemical conversion stage continuously provides the capture liquid for the capture stage, and the capture stage continuously provides the electrolyte for the electrochemical conversion stage.

[0056] Example 2

[0057] In a typical embodiment of the present invention, a method for co-capturing and converting flue gas carbon dioxide to produce formate is proposed:

[0058] Taking the bicarbonate solution or carbamate solution in the carbon dioxide capture tank as the initial cathode electrolyte (carbon-rich capture liquid) for electrochemical conversion treatment to produce formate. During the electrolysis process, the capture liquid is generated at the same time. The obtained capture liquid is immediately transported to the carbon dioxide capture tank for capturing the flue gas carbon dioxide to re-obtain the carbon-rich capture liquid. The regenerated carbon-rich capture liquid is also continuously supplied to the cathode chamber of the electrolytic cell for electrochemical conversion to produce formate. The above carbon-rich capture liquid electrochemical conversion process and the flue gas carbon dioxide capture process occur continuously and synchronously in the same closed system, thereby realizing the co-capture and electrochemical conversion of flue gas carbon dioxide.

[0059] At this time, the carbon-rich capture liquid continues to be continuously supplied to the cathode chamber of the electrolytic cell for electrochemical conversion to produce formate. The above carbon-rich capture liquid electrochemical conversion process and the flue gas carbon dioxide capture process are not independent and do not stagnate. The two processes occur continuously and synchronously in the same closed system. While the electrochemical conversion stage provides the capture liquid for the capture stage, the capture stage also continuously provides the electrolyte for the electrochemical conversion stage, thereby realizing the co-capture and electrochemical conversion of flue gas carbon dioxide.

[0060] Specifically, in the cathode chamber 1 of the electrolytic cell, a formate is obtained by electrochemically converting a carbon-rich capture liquid, and the capture liquid is recycled to the carbon dioxide capture tank 3 to directly capture flue gas carbon dioxide and re-obtain the carbon-rich capture liquid. The carbon-rich capture liquid is continuously supplied to the cathode chamber 1 of the electrolytic cell by the pump 2 for electrochemical conversion. The above process continuously operates in a cycle, continuously electrolyzing to obtain formate and continuously capturing flue gas carbon dioxide.

[0061] In this embodiment, taking the initial electrolyte as a 3 mol / L potassium bicarbonate solution and the catalyst as a bismuth oxide catalyst supported by a carbon material as an example, the process of electrochemically converting the carbon-rich capture liquid to produce formate in the method is achieved through the following reactions (1) and (2):

[0062]

[0063] CO2 + H2O + 2e - →HCOO - + OH - (2)

[0064] The carbon dioxide capture process in the method is achieved through the following reactions (3) and (4):

[0065]

[0066] At the same time, the following reaction (5) occurs at the anode:

[0067]

[0068] Among them, the overall process of real-time synchronous capture of flue gas carbon dioxide and conversion to produce formate is as follows:

[0069] In the electrochemistry conversion stage, since the reaction continuously proceeds, in-situ carbon dioxide is continuously dissociated and generated. The carbon dioxide dissociated from the potassium bicarbonate solution is electrocatalytically converted to formate (2), and hydroxide ions and carbonate ions are generated simultaneously during the electrolysis process.

[0070] In the capture stage, the hydroxide ions and carbonate ions generated during the above electrolysis process are recycled to the carbon dioxide capture tank, and reactions (3) and (4) occur to achieve the capture of carbon dioxide in the flue gas and re-obtain the potassium bicarbonate solution.

[0071] The above process of electrochemically converting the carbon-rich capture liquid and the process of capturing flue gas carbon dioxide both occur in the same continuous system. The electrochemistry conversion stage continuously provides the capture liquid for the capture stage, and the capture stage continuously provides the carbon-rich capture liquid for the electrochemistry conversion stage.

[0072] In this embodiment, a 3 mol / L potassium bicarbonate solution is used as the initial cathode electrolyte for the co-capture and conversion of flue gas carbon dioxide to produce formate. The cathode catalyst material used is bismuth oxide catalyst, and the catalyst loading is 4 mg / cm 2 . In the cathode chamber, the 3 mol / L potassium bicarbonate solution is electrochemically converted to obtain the target product formate and a capture solution is generated. The capture solution is circulated into the carbon dioxide capture tank to capture flue gas carbon dioxide and regenerate the potassium bicarbonate solution; the anode catalyst used in the anode chamber is a titanium mesh coated with iridium oxide, and the anode electrolyte is a 1 mol / L potassium hydroxide solution; a bipolar membrane is used to separate the anode chamber and the cathode chamber of the electrolytic cell.

[0073] Example 3: This example conducts a demonstration evaluation test on the co-capture and electrochemical conversion performance of flue gas carbon dioxide

[0074] Long-term performance evaluation of the co-capture and conversion of flue gas carbon dioxide to produce formate based on potassium bicarbonate solution

[0075] Experimental procedure: A membrane electrode electrolytic cell is used. The cathode electrolyte is a 3 mol / L potassium bicarbonate solution, and the anode electrolyte is a 1 mol / L potassium hydroxide solution. At a current density of 100 mA / cm 2 , the potassium bicarbonate solution continuously fed with simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, flow rate of 10 sccm) is electrolyzed for 24 hours. The formate product is quantitatively detected by nuclear magnetic resonance hydrogen spectrum, and the capture and utilization of flue gas carbon dioxide are monitored simultaneously.

[0076] Figure 2 For the nuclear magnetic resonance hydrogen spectrum of formate generated by electrolyzing the potassium bicarbonate solution continuously fed with simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, flow rate of 10 sccm) for 30 minutes at a current density of 100 mA / cm 2 .

[0077] Figure 3 For the Faraday efficiency of formate generated by electrolyzing the potassium bicarbonate solution continuously fed with simulated flue gas with different components (15% carbon dioxide, 80% nitrogen, 5% oxygen; 15% carbon dioxide, 85% nitrogen, 200 ppm NO; 15% carbon dioxide, 85% nitrogen, 200 ppm SO2, flow rate of 10 sccm each) for 30 minutes at a current density of 100 mA / cm 2 .

[0078] Figure 4 For the change trend of the carbon dioxide capture and utilization rate during the 24-hour electrolysis of the potassium bicarbonate solution continuously fed with simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, flow rate of 10 sccm) at a current density of 100 mA / cm 2 .

[0079] Figure 5 At a current density of 100 mA / cm 2 The change trend of the Faraday efficiency of formate production during the 24-hour electrolysis of a potassium bicarbonate solution continuously fed with simulated flue gas (15% carbon dioxide, 80% nitrogen, 5% oxygen, and a flow rate of 10 sccm).

[0080] It can be seen from Figures 2 to 5 that in the system for synergistic capture and conversion of flue gas carbon dioxide to produce formate, the Faraday efficiency of formate during electrochemical conversion is not affected by a small amount of oxygen, trace nitrogen oxides, and sulfur oxide gas impurities in the flue gas. That is, without the need for pretreatment of the flue gas, this system can efficiently capture and electrochemically convert carbon dioxide in flue gas containing various gas impurities. During the electrochemical conversion process, the Faraday efficiency of formate fluctuates within a small range, and the Faraday efficiency of formate remains at about 40% at 24 h; during the 24-hour electrolysis process, carbon dioxide is captured and utilized to varying degrees, and the highest capture and utilization rate of flue gas carbon dioxide reaches 48% at 24 h.

[0081] The above experimental results show that a method for synergistic capture and conversion of flue gas carbon dioxide to produce formate provided by the present invention exhibits the ability to synergistically capture and convert carbon dioxide in flue gas containing gas impurities.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for co-capturing and converting carbon dioxide in flue gas to produce formate, characterized in that, It includes the following processes: Taking the bicarbonate solution or carbamate solution in the carbon dioxide capture tank as the initial cathode electrolyte for electrocatalytic conversion to produce formate, and simultaneously generating the capture liquid during the electrolysis process; the obtained capture liquid is immediately transported to the carbon dioxide capture tank for capturing flue gas carbon dioxide to obtain the carbon-rich capture liquid, and at the same time, it continues to be supplied to the cathode chamber of the electrolytic cell for electrocatalytic conversion to produce formate; the electrocatalytic conversion process and the flue gas carbon dioxide capture process occur continuously and synchronously in the same closed system, realizing the coordinated capture and electrocatalytic conversion of flue gas carbon dioxide.

2. The method according to claim 1, characterized in that, The concentrations of both the bicarbonate solution and the carbamate solution are 0.1 - 5 mol / L.

3. The method according to claim 1, wherein The main components of the capture liquid are hydroxides, carbonates or amino-containing compounds.

4. The method according to claim 3, wherein The hydroxides include potassium hydroxide, sodium hydroxide, lithium hydroxide and cesium hydroxide; the carbonates include potassium carbonate, sodium carbonate, lithium carbonate and cesium carbonate; the amino-containing compounds include amino acid compounds and organic amine compounds.

5. A flue gas carbon dioxide co-capture and conversion system for producing formate based on the method according to any one of claims 1 to 4, characterized in that, It includes: A carbon dioxide coordinated capture and conversion module and an anodic side reaction module; the carbon dioxide coordinated capture and conversion module includes a cathode assembly and a carbon dioxide capture tank, the cathode assembly includes an electrolytic cell cathode chamber and a pump; the anodic side reaction module includes an electrolytic cell anode chamber; the electrolytic cell cathode chamber and the electrolytic cell anode chamber are separated by an ion exchange membrane.

6. The system according to claim 5, wherein The liquid outlet end of the electrolytic cell cathode chamber is connected to the liquid inlet end of the pump, the liquid outlet end of the pump is connected to the liquid inlet end of the carbon dioxide capture tank, and the liquid outlet end of the carbon dioxide capture tank is connected to the liquid inlet end of the electrolytic cell cathode chamber; the gas inlet of the carbon dioxide capture tank is connected to the flue gas source.

7. The system according to claim 5, wherein The ion exchange membrane is selected from one of bipolar membranes, cation exchange membranes, and anion exchange membranes, and is used to separate the cathode chamber and the anode chamber and conduct ion transport.

8. The system according to claim 5, characterized in that, The electrolyte of the electrolytic cell anode chamber is a potassium hydroxide solution with a concentration of 0.5 - 5 mol / L.

9. The system according to claim 5, wherein The electrolytic cell cathode chamber is used for electrochemically converting the carbon-rich capture liquid to obtain the target product formate and generating the capture liquid, and the electrolytic cell anode chamber is used for electrochemically converting the anodic electrolyte to generate oxygen.

10. The system according to claim 4, wherein The anode material used in the electrolytic cell anode chamber is nickel foam, platinum mesh or titanium mesh, preferably titanium mesh coated with iridium oxide, and the cathode catalyst used in the electrolytic cell cathode chamber is metals such as indium, tin, lead, bismuth and cobalt and their oxide / sulfide materials, preferably bismuth oxide catalyst.

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