Carbon dioxide capture method and system capable of simultaneously producing carbon monoxide and hydrogen gas

Abstract

A method and system for collecting carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas is provided. The method for collecting carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas includes the steps of collecting carbon dioxide as a target component using an alkaline solution to obtain a carbonate-containing aqueous solution, performing a first electrolysis process on the carbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution and hydrogen gas, and performing a second electrolysis process on the bicarbonate-containing aqueous solution in the presence of a catalyst to obtain carbon monoxide and hydrogen gas, the catalyst being one or more selected from the group consisting of metal elements, alloys, and compounds of Groups VIII, IB, IIB, IVA, and lanthanoid elements. The method allows the collected carbon dioxide to be consumed and used as a synthetic gas, further expanding the application field of carbon dioxide resource recovery, and also significantly reducing power consumption and process costs by converting a part of the carbonate in the carbonate solution into bicarbonate before the first electrolysis process.

Description

[Technical field]

[0001] This application is based on and claims priority from a Chinese application having Chinese application number 202210311730.8 and filing date March 28, 2022, the disclosure of which is hereby incorporated by reference in its entirety into this application. The present invention relates to the field of carbon dioxide capture, and more particularly to a method and system for carbon dioxide capture capable of co-producing carbon monoxide and hydrogen gas. [Background technology]

[0002] At present, chemical absorption using liquid alkanolamine as CO2 absorbent has the advantages of fast absorption rate and simple process, and is currently one of the most widely studied and most widely used technologies for CO2 capture. However, the regeneration process of alkanolamine absorbent requires the use of a large amount of steam to absorb a certain amount of water vaporization latent heat, which consumes a lot of energy. In addition, the alkanolamine solvent decomposes to a certain extent during use, which causes amine loss and increased running costs.

[0003] In order to solve the problem of high energy consumption when using liquid alkanolamine solvents, CO2 capture using solid adsorbents / absorbents has become a hot research topic. The regeneration process of such adsorbents / absorbents avoids the heat of vaporization of a large amount of water, and the energy consumption is mainly the sensible heat of temperature rise of the material during the regeneration process and the heat of chemical reaction required for regeneration, so the regeneration energy consumption is greatly reduced. However, this method has high requirements for solid adsorbents / absorbents, and the adsorbents used must have both excellent adsorption performance and thermal stability, but the adsorbents / absorbents with excellent performance are generally expensive, which increases the initial investment cost. Meanwhile, it is necessary to develop the corresponding process equipment and process flow, and the related adsorption and regeneration equipment is usually mainly fluidized bed, which inevitably causes material wear during operation, resulting in a certain amount of adsorbent / absorbent loss, and increasing the running cost. Therefore, at present, relatively mature industrial applications have not yet been reported.

[0004] CO2 capture using inorganic alkaline solution as absorbent is cheaper than solid adsorption / absorption. In addition, the carbonate obtained by absorbing CO2 with inorganic alkali can usually be regenerated by reacting with Ca(OH)2. Compared with chemical absorption method using alkanolamine solvent as absorbent, this method avoids the latent heat of vaporization of a large amount of water during the regeneration process. However, the Ca(OH)2 that needs to be used in the regeneration process becomes CaCO3, and CaCO3 needs to be calcined to become CaO and react with H2O again to realize the regeneration of Ca(OH)2. Therefore, the system of this method is complicated, and in addition, the calcination of CaCO3 increases energy consumption, and the consumption of calcination fuel leads to CO2 emission, and it is not excellent in both investment cost and running cost. Therefore, how to reduce the cost of CO2 capture is the main focus of current research. Another point of current research is to turn CO2 into a resource and use it. The final products obtained by the mainstream carbon capture technology in the market are basically CO2 as the main component, and the carbon element is used in a single form. The captured CO2 can be used to synthesize chemical products such as CO2-based methanol and CO2-based alkenes, but the types and production capacity of chemical products that need to be synthesized using CO2 as raw material are limited. Therefore, how to further expand the application fields of CO2 as a resource, consume captured CO2 in a timely manner, and form a complete industrial chain is an important research direction.

[0005] In view of the above problems, there is a need to develop a method for capturing CO2 that can simultaneously produce CO and H2. Summary of the Invention [Problem to be solved by the invention]

[0006] The main object of the present invention is to provide a carbon dioxide capture method and system capable of simultaneously producing carbon monoxide and hydrogen gas, in order to solve the problems of high capture costs and a single product in conventional carbon dioxide capture methods. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of the present invention provides a method for collecting carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas, the method comprising the steps of: collecting carbon dioxide in a target component using an alkaline solution to obtain a carbonate-containing aqueous solution, performing a first electrolysis process on the carbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution and hydrogen gas, and performing a second electrolysis process on the bicarbonate-containing aqueous solution in the presence of a catalyst to obtain carbon monoxide and hydrogen gas, the catalyst being one or more selected from the group consisting of simple metals, alloys and compounds of Group VIII, Group IB, Group IIB, Group IVA and the lanthanoid elements.

[0008] Furthermore, the product of the first electrolysis process further includes a first crude oxygen gas, which contains a portion of carbon dioxide, and the method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas further includes a step of purifying the first crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain pure oxygen gas and a bicarbonate-containing aqueous solution, and a step of performing a first electrolysis process on the bicarbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution.

[0009] Furthermore, in the first electrolysis process, the electrolytic cell voltage is 1.1 to 4 V, and the current density is 500 to 8000 A / m 2 The carbonate-containing aqueous solution has a pH of 10 to 14 and a carbonate concentration of 1 to 4.5 mol / L.

[0010] Furthermore, the product of the first electrolysis process further includes a regenerated alkaline solution, and the method for capturing carbon dioxide capable of co-producing carbon monoxide and hydrogen gas further includes a step of involving at least a portion of the regenerated alkaline solution and / or the catholyte obtained in at least the second electrolysis process in the capturing process as an alkaline solution.

[0011] Additionally, at least a portion of the regenerated alkaline solution is cooled before participating in the collection process.

[0012] Furthermore, in the second electrolysis process, the electrolytic cell voltage is 100-220V, and the current density is 500-10000A / m 2 The catalyst loading is 1 to 200 mg / cm 2 The pH of the bicarbonate-containing aqueous solution is 8 to 13, and the concentration of bicarbonate in the bicarbonate-containing aqueous solution is 1.5 to 3.8 mol / L.

[0013] Furthermore, the operating temperature of the first electrolysis step is 70-95°C, and the operating temperature of the second electrolysis step is 20-90°C.

[0014] Furthermore, the catalyst is one or more selected from the group consisting of metallic Au, metallic Ni, metallic Zn, CuPb, CeO2, and ZnO, and the amount of the catalyst supported is 30 to 80 mg / cm 2 It is.

[0015] Furthermore, the product of the second electrolysis process further includes a second crude oxygen gas, which contains a portion of carbon dioxide, and the method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas further includes a step of purifying the second crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain pure oxygen gas and a bicarbonate-containing aqueous solution.

[0016] Furthermore, during the collection process, the pressure is normal pressure, the concentration of the carbonate-containing aqueous solution is 1 to 4.5 mol / L, and the pH is 10 to 13.

[0017] Furthermore, in the refining process, the ratio of the molar amount of the bicarbonate radicals to the total molar amount of the carbonate radicals and the bicarbonate radicals in the bicarbonate-containing aqueous solution is (0.1-1:1).

[0018] Furthermore, the carbon dioxide capture method capable of co-producing carbon monoxide and hydrogen gas further includes a step of reintroducing a portion of the carbonate-containing aqueous solution into the capture process.

[0019] Furthermore, the molar ratio of carbon monoxide to hydrogen gas obtained in the second electrolysis process is (0.1-1:1).

[0020] Another aspect of the present invention further provides a carbon dioxide capture system capable of co-producing carbon monoxide and hydrogen gas, the carbon dioxide capture system capable of co-producing carbon monoxide and hydrogen gas, comprising a carbon dioxide capture device, a first electrolysis device, and a second electrolysis device, the carbon dioxide capture device being provided with an alkaline solution inlet, a target component inlet, and a carbonate-containing aqueous solution outlet, the first electrolysis device being provided with a carbonate-containing aqueous solution inlet, a bicarbonate-containing aqueous solution outlet, and a hydrogen gas outlet, the carbonate-containing aqueous solution outlet being connected to the carbonate-containing aqueous solution inlet, a catalyst being provided inside the second electrolysis device, and the first electrolysis device being provided with a bicarbonate-containing aqueous solution inlet and a cathode gas outlet, the cathode gas outlet being used to discharge carbon monoxide and hydrogen gas, the catalyst being one or more selected from the group consisting of elemental metals, alloys, and compounds of Group VIII, Group IB, Group IIB, Group IVA, and lanthanoid elements.

[0021] In addition, the first electrolysis device is further equipped with a first crude oxygen outlet, and the carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes a purification device, in which a crude oxygen inlet, an alkaline absorbent inlet and a hydrogen carbonate-containing aqueous solution outlet are provided, the crude oxygen inlet is connected to the first crude oxygen outlet, and the hydrogen carbonate-containing aqueous solution outlet is connected to the hydrogen carbonate-containing aqueous solution inlet.

[0022] Furthermore, the carbonate-containing aqueous solution outlet is connected to the alkaline absorbent inlet and the alkaline solution inlet, respectively.

[0023] In addition, the first electrolysis device further includes a regenerated alkaline solution outlet, and the regenerated alkaline solution outlet and the alkaline solution inlet are connected via a regenerated alkaline solution transport pipeline.

[0024] Furthermore, the carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes a buffer device and a cooling device, which are sequentially installed in the regenerated alkaline liquid transport pipeline along the flow direction of the regenerated alkaline liquid.

[0025] In addition, the second electrolysis device is further provided with a catholyte outlet and a second crude oxygen outlet, the catholyte outlet being connected to the alkaline solution inlet, and the second crude oxygen outlet being connected to the crude oxygen inlet. Effect of the Invention

[0026] By applying the technical solution of the present invention, the carbon dioxide is captured from the target component (such as air or combustion exhaust gas) and converted into a carbonate-containing aqueous solution through the above method, thereby realizing the purpose of reducing carbon dioxide emissions. The carbonate-containing aqueous solution is lightly electrolyzed through the first electrolysis process to convert the carbonate into bicarbonate, thereby realizing the regeneration of the alkaline absorption solution, and also producing some hydrogen gas as a by-product. Due to the action of the catalyst, the bicarbonate undergoes a catalytic electrolysis reaction in the second electrolysis process to obtain carbon monoxide and hydrogen gas. Through the above method, the captured carbon dioxide can be consumed and utilized as a synthetic gas, further expanding the application field of carbon dioxide resource utilization. In addition, a part of the carbonate in the carbonate solution is converted into bicarbonate before the first electrolysis process, thereby greatly reducing power consumption and process costs. [Brief description of the drawings]

[0027] The drawings forming a part of this application are intended to provide a further understanding of the present invention, and the illustrative embodiments of the present invention and the description thereof are intended to interpret the present invention and are not intended to unduly limit the present invention. [Figure 1] FIG. 1 is a structural schematic diagram of a carbon dioxide capture device capable of simultaneously producing carbon monoxide and hydrogen gas according to the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] It should be noted that, unless contradictory, the embodiments and features in the embodiments in the present application can be combined with each other.

[0029] As described in the Background Art, the conventional carbon dioxide capture method has the problem that the capture cost is high and the product is single. In order to solve the above problems, the present application provides a carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas. The carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas includes the steps of: capturing carbon dioxide in a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; performing a first electrolysis process on the carbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution and hydrogen gas; and performing a second electrolysis process on the bicarbonate-containing aqueous solution in the presence of a catalyst to obtain carbon monoxide and hydrogen gas, the catalyst being one or more selected from the group consisting of metals, alloys, and compounds of Group VIII, Group IB, Group IIB, Group IVA, and lanthanoid elements.

[0030] The above method captures carbon dioxide from the target components (e.g., air or combustion exhaust gas) and converts it into a carbonate-containing aqueous solution, thereby achieving the purpose of reducing carbon dioxide emissions. The carbonate-containing aqueous solution is lightly electrolyzed in the first electrolysis process to convert the carbonate into bicarbonate, thereby realizing the regeneration of the alkaline absorption solution and also producing some hydrogen gas as a by-product. Due to the action of the catalyst, the bicarbonate undergoes a catalytic electrolysis reaction in the second electrolysis process to obtain carbon monoxide and hydrogen gas. The above method allows the captured carbon dioxide to be consumed and used as a synthetic gas, further expanding the application field of carbon dioxide resource utilization. In addition, a part of the carbonate in the carbonate solution is converted into bicarbonate before the first electrolysis, thereby significantly reducing power consumption and process costs.

[0031] In a preferred embodiment, the product of the first electrolysis process further includes a first crude oxygen gas, which contains a portion of carbon dioxide, and the method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas further includes a step of purifying the first crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain pure oxygen gas and a bicarbonate-containing aqueous solution, and a step of performing a first electrolysis process on the bicarbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution.

[0032] By purifying the first crude oxygen gas using the carbonate-containing aqueous solution obtained in the carbon dioxide capture process, the carbon dioxide carried away in the oxygen gas can be recovered, which is advantageous to improving the capture efficiency of carbon dioxide in the capture process. In addition, in the above purification process, a part of the carbonate in the carbonate-containing aqueous solution can be converted into hydrogen carbonate, which can be used as the electrolyte in the first electrolysis process, thereby reducing the power consumption in the first electrolysis process to a certain extent, and ultimately reducing the energy consumption of the system and the cost of the entire process.

[0033] The carbonate-containing aqueous solution can be converted into a hydrogencarbonate-containing aqueous solution by the first electrolysis process. In a preferred embodiment, the electrolytic cell voltage is 1.1-4 V and the current density is 500-8000 A / m 2 The pH of the carbonate-containing aqueous solution is 10 to 14, and the carbonate concentration in the carbonate-containing aqueous solution is 1 to 4.5 mol / L. The electrolytic cell voltage, current density, pH of the carbonate-containing aqueous solution, and carbonate concentration in the first electrolysis process include, but are not limited to, the above-mentioned ranges, and limiting them to the above-mentioned ranges is advantageous for further improving the conversion rate of hydrogencarbonate.

[0034] In a preferred embodiment, the product of the first electrolysis process further includes a regenerated alkaline solution, and the method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas further includes a step of using at least a part of the regenerated alkaline solution and / or the catholyte obtained in at least the second electrolysis process as an alkaline solution in the capturing process. A part of the alkaline solution (regenerated alkaline solution) can be regenerated in the first electrolysis process, and this is used again as a collector in the carbon dioxide capture process, which is favorable for improving the raw material utilization rate in the entire process and therefore favorable for further reducing costs.

[0035] Generally, after the first electrolysis process, the regenerated alkaline solution has a certain temperature, and in order to prevent the regenerated alkaline solution from affecting the absorption of carbon dioxide during the reuse process, it is preferable to first perform a cooling treatment on at least a part of the regenerated alkaline solution before it is used in the collection process.

[0036] In a preferred embodiment, in the second electrolysis step, the electrolytic cell voltage is 100-220V, and the current density is 500-10000A / m 2 The catalyst loading is 1 to 200 mg / cm 2 The pH of the bicarbonate-containing aqueous solution is 8 to 13, and the concentration of bicarbonate in the bicarbonate-containing aqueous solution is 1.5 to 3.8 mol / L. The electrolytic cell voltage, current density, catalyst loading, pH of the bicarbonate-containing aqueous solution, and bicarbonate concentration in the second electrolysis process include, but are not limited to, the above-mentioned ranges, and limiting them to the above-mentioned ranges is advantageous for further improving the yield of carbon monoxide.

[0037] Preferably, the operating temperature of the first electrolysis step is 70-95° C., and the operating temperature of the second electrolysis step is 20-90° C. Since the temperature has a certain effect on the efficiency of the electrolysis step, limiting the operating temperatures of the first electrolysis step and the second electrolysis step within the above ranges is advantageous for further improving the yield of carbon monoxide.

[0038] In order to further improve the yield and reaction activity of carbon monoxide, the catalyst used in the present application preferably includes, but is not limited to, one or more selected from the group consisting of metallic Au, metallic Ni, metallic Zn, CuPb, CeO2, and ZnO, and the catalyst loading is 30 to 80 mg / cm 2 It is.

[0039] A certain amount of crude oxygen gas (second crude oxygen gas) is also produced in the second electrolysis process, and the second crude oxygen gas contains a portion of carbon dioxide. In order to recover the carbon dioxide in the second crude oxygen gas and improve the utilization rate of carbon element, the carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas preferably further includes a step of purifying the second crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain pure oxygen gas and a hydrogen carbonate-containing aqueous solution.

[0040] In a preferred embodiment, the pressure is normal pressure, the concentration of the carbonate-containing aqueous solution is 1-4.5 mol / L, and the pH is 10-13 during the collection process.

[0041] In a preferred embodiment, in the purification process, the molar ratio of the bicarbonate radical to the total molar amount of the carbonate radical and the bicarbonate radical is (0.1-1):1. The molar ratio of the bicarbonate radical to the total molar amount of the carbonate radical and the bicarbonate radical includes but is not limited to the above range, and being limited to the above range is advantageous for improving the CO yield in the second electrolysis process. The first electrolysis process also produces some hydrogen gas, which can be mixed with the carbon monoxide and hydrogen gas produced in the second electrolysis process to flexibly adjust the ratio of carbon monoxide and hydrogen in the synthesis gas.

[0042] Preferably, the molar ratio of carbon monoxide to hydrogen obtained in the second electrolysis step is (0.1-1:1).

[0043] A second aspect of the present application further provides a carbon dioxide capture system capable of co-producing carbon monoxide and hydrogen gas. The carbon dioxide capture system capable of co-producing carbon monoxide and hydrogen gas includes a carbon dioxide capture device 10, a first electrolysis device 20, and a second electrolysis device 30. The carbon dioxide capture device 10 is provided with an alkaline solution inlet 101, a target component inlet 102, and a carbonate-containing aqueous solution outlet 103. The electrolysis device is provided with a carbonate-containing aqueous solution inlet 201, a bicarbonate-containing aqueous solution outlet 202, and a hydrogen gas outlet 203, and the carbonate-containing aqueous solution outlet 103 is connected to the carbonate-containing aqueous solution inlet 201. A catalyst is installed inside the second electrolysis device 30, and a bicarbonate-containing aqueous solution inlet and a cathode gas outlet are installed in the first electrolysis device 20, the cathode gas outlet is used to discharge carbon monoxide and hydrogen, and the catalyst is one or more selected from the group consisting of metal elements, alloys and compounds of Group VIII, Group IB, Group IIB, Group IVA and lanthanoids.

[0044] The carbon dioxide capture device 10 captures carbon dioxide from target components such as air or combustion exhaust gas and converts it into a carbonate-containing aqueous solution, thereby reducing carbon dioxide emissions. The first electrolysis device 20 lightly electrolyzes the carbonate-containing aqueous solution to convert the carbonate into hydrogen carbonate, thereby regenerating the alkaline absorption solution and producing some hydrogen gas as a by-product. The hydrogen carbonate undergoes a catalytic electrolysis reaction in the second electrolysis device 30 due to the action of a catalyst, resulting in carbon monoxide and hydrogen gas. The above capture system allows the captured carbon dioxide to be consumed and used as a synthetic gas, further expanding the application field of carbon dioxide resource recovery. In addition, by converting some of the carbonate in the carbonate solution into hydrogen carbonate before the first electrolysis, power consumption and process costs are significantly reduced.

[0045] In a preferred embodiment, the first electrolysis device 20 is further provided with a first crude oxygen outlet, and the carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes an oxygen purification device 40, which is provided with a crude oxygen inlet 401, an alkaline absorbent inlet 402, and a bicarbonate-containing aqueous solution outlet 403, the crude oxygen inlet 401 being connected to the first crude oxygen outlet, and the bicarbonate-containing aqueous solution outlet 403 being connected to the bicarbonate-containing aqueous solution inlet. In the oxygen purification device 40, the carbonate-containing aqueous solution obtained in the carbon dioxide capture device 10 is used to purify the first crude oxygen gas, so that the carbon dioxide carried out in the oxygen gas can be recovered, which is advantageous to improving the capture efficiency of carbon dioxide in the capture process. In addition, in the above purification process, a part of the carbonate in the carbonate-containing aqueous solution can be converted into bicarbonate, which can be used as the electrolyte of the first electrolysis device 20, which can reduce the power consumption of the first electrolysis device 20 to a certain extent, ultimately reducing the energy consumption of the system and reducing the overall process cost.

[0046] In order to further improve the utilization rate of the raw materials and reduce the process cost, the carbonate-containing aqueous solution outlet 103 preferably communicates with the alkaline absorbent inlet 402 and the alkaline solution inlet 101 respectively.

[0047] In order to further improve the utilization rate of the raw materials and reduce the process cost, in a preferred embodiment, the first electrolysis device 20 further includes a regenerated alkaline solution outlet 204, and the regenerated alkaline solution outlet 204 and the alkaline solution inlet 101 are connected through a regenerated alkaline solution transport pipeline.

[0048] Preferably, the carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes a buffer unit 50 and a cooling unit 60, which are sequentially installed in the regenerated alkaline liquid transport pipeline along the flow direction of the regenerated alkaline liquid. In the buffer unit 50, the concentration and pH of the regenerated alkaline liquid can be adjusted by adding water separately. Generally, the regenerated alkaline liquid discharged after the first electrolysis has a certain temperature, so that the installation of the cooling unit 60 is advantageous in suppressing the influence of carbon dioxide absorption during the reuse process of the regenerated alkaline liquid.

[0049] The second electrolysis device 30 also discharges a certain amount of crude oxygen gas (second crude oxygen gas), and the second crude oxygen gas contains a portion of carbon dioxide. In order to recover the carbon dioxide in the second crude oxygen gas and improve the utilization rate of carbon elements, the second electrolysis device 30 is preferably further provided with a catholyte outlet and a second crude oxygen outlet, the catholyte outlet communicates with the alkaline solution inlet 101, and the second crude oxygen outlet communicates with the crude oxygen inlet 401.

[0050] The present application will now be described in more detail with reference to specific examples, which should not be construed as limitations on the scope of protection claimed by the present application.

[0051] [Example 1] A method for capturing carbon dioxide that can co-produce carbon monoxide and hydrogen gas includes the following steps.

[0052] In the carbon dioxide capture apparatus 10, the carbon dioxide capture process includes: an alkaline solution enters the carbon dioxide capture apparatus 10 through an alkaline solution inlet 101; a target component enters the carbon dioxide capture apparatus 10 through a target component inlet; and the alkaline solution captures the carbon dioxide in the target component to obtain a carbonate-containing aqueous solution. Here, the target component is air, the volume fraction of carbon dioxide is 400 ppm, the alkaline solution is a 1.1 mol / L KOH aqueous solution, and the carbonate-containing aqueous solution is a 2.1 mol / L K2CO3 solution with a pH of 13.6. The carbonate-containing aqueous solution is discharged from a carbonate-containing aqueous solution outlet 103, and the uncaptured gas is discharged from a top gas outlet 104.

[0053] The carbonate-containing aqueous solution is controlled by the carbonate-containing aqueous solution transport pump 11 and the flow rate control valve 12 to enter the first electrolysis device 20 through the carbonate-containing aqueous solution inlet 201. The first electrolysis process includes the following: Put the above K2CO3 solution into the electrolysis cell, set the electrolysis cell voltage to 2.6 V, and set the current density to 1560 A / m 2 The cathode obtains a KOH solution (regenerated alkaline solution) and hydrogen gas, the hydrogen gas is discharged from the hydrogen gas outlet 203, and the obtained KOH solution is discharged from the regenerated alkaline solution outlet 204. The KOH solution is transported to the buffer device 50 by the regenerated alkaline solution transport pump 22, and the pH is adjusted by adding water to the buffer device 50 through the external water supply transport pipe 51. The KOH solution is then cooled in the cooling device 60 and returned to the carbon dioxide capture device 10 through the alkaline solution inlet 101 for reuse. The anode obtains a KHCO3 solution (aqueous solution containing bicarbonate) with a concentration of 2.4 mol / L and a first crude oxygen gas containing CO2 with a dry basis volume fraction of 42%. The aqueous solution containing bicarbonate is discharged from the aqueous solution containing bicarbonate outlet 403, and the first crude oxygen gas is discharged from the first crude oxygen gas outlet.

[0054] The first electrolysis device anolyte is transported to the second electrolysis device 30 by the anolyte transport pump 21. The second electrolysis process includes the following: The KHCO3 solution obtained at the anode of the first electrolysis process is transported to the electrolysis cell, and the electrolysis cell voltage is set to 150 V and the current density is set to 2500 A / m 2The electrolysis temperature was set to 45°C, and the catalyst loading on the electrolytic cell ion membrane was set to 36mg / cm 2 The catalyst used is metallic Au. At the cathode, synthesis gas with a molar ratio of CO and H2 of 0.49:1 and catholyte are obtained. At the anode, second crude oxygen gas containing 9% CO2 by volume fraction on a dry basis is obtained. The second crude oxygen gas is discharged from the second crude oxygen gas outlet, and the catholyte is returned to the carbon dioxide capture device 10 from the alkaline solution inlet by the second electrolysis device catholyte transport pump 31.

[0055] The first and second crude oxygen gases are transported by the anode gas transport fan 23 and enter the oxygen purification device 40 from the crude oxygen inlet 401. The alkaline absorbent (at least a portion of the carbonate-containing aqueous solution obtained in the carbon dioxide capture process) enters the oxygen purification device 40 from the alkaline absorbent inlet 402. The purification process includes the following. Before performing the first electrolysis on a portion of the carbonate-containing aqueous solution obtained in the carbon dioxide capture process, the first and second crude oxygen gases are purified using the portion of the solution to obtain a bicarbonate-containing aqueous solution and purified oxygen gas. Here, the bicarbonate-containing aqueous solution has a ratio of the molar amount of bicarbonate roots to the total molar amount of carbonate roots and bicarbonate roots of 0.23:1, and is discharged from the bicarbonate-containing aqueous solution outlet 403, and then is fed into the electrolysis cell of the first electrolysis device 20 by the purified bottom liquid transport pump 41, where the electrolysis operation is performed. The oxygen gas is discharged from the top exhaust port 404.

[0056] In this embodiment, it can be seen that under the above conditions, the CO2 capture rate is 51%. Compared with the case where the first electrolysis process is directly performed on the carbonate solution, the refining process can improve the recovery rate of the captured CO2 from the conventional 70% to 98.6%, and the refining process converts K2CO3 in a part of the carbonate solution obtained in the carbon dioxide capture process into KHCO3, reducing the energy consumption of the first electrolysis process to 13.6%. The second electrolysis process achieves a single-pass conversion rate of carbon dioxide of 28.7%, and the H2 obtained in the first electrolysis process can be doped with the synthesis gas obtained in the second electrolysis process according to downstream demand, so that the carbon-hydrogen ratio of the final synthesis gas can be adjusted within a predetermined range, realizing flexible adjustment.

[0057] [Example 2] This example is different from Example 1 in that the catalyst is metallic Zn.

[0058] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 15.3%.

[0059] [Example 3] This example is different from Example 1 in that the catalyst is metallic Ni.

[0060] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 16.1%.

[0061] [Example 4] This is different from Example 1 in that the catalyst is CuPb.

[0062] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 24.6%.

[0063] [Example 5] This is different from Example 1 in that the catalyst is CeO2.

[0064] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 22.3%.

[0065] [Example 6] This is different from Example 1 in that the catalyst is ZnO.

[0066] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 19.4%.

[0067] [Example 7] Compared with Example 1, the catalyst loading was 30 mg / cm 2 The difference is that

[0068] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 24.6%.

[0069] [Example 8] Compared with Example 1, the catalyst loading was 80 mg / cm 2 The difference is that

[0070] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 29.8%.

[0071] [Example 9] Compared to Example 1, the catalyst loading was 16 mg / cm 2 The difference is that

[0072] Through the second electrolysis process, the single-pass conversion rate of carbon dioxide was 20.4%.

[0073] From the above description, it can be seen that the above embodiments of the present invention can achieve the following technical effects.

[0074] (1) In the system and method for CO2 capture and utilization capable of simultaneously producing CO and H2 according to the present invention, the carbonate-containing aqueous solution from the CO2 absorption tower is used to refine crude O2, and the CO2 carried away by the O2 is recovered, thereby ensuring the capture efficiency of the system. At the same time, some of the carbonates in the carbonate-containing aqueous solution are converted to hydrogen carbonate, which is then fed into an electrolytic cell for electrolysis, thereby reducing the power consumption of the electrolytic cell to a certain extent, and ultimately reducing the energy consumption of the system.

[0075] (2) In the system and method for capturing and utilizing CO2 capable of simultaneously producing CO and H2 according to the present invention, the captured CO2 is reacted with water through secondary catalytic electrolysis and is ultimately converted into a synthesis gas of CO and H2. This allows the captured CO2 to be consumed and utilized as a synthesis gas, further expanding the application fields of CO2 resource utilization.

[0076] (3) In the system and method for CO2 capture and utilization capable of simultaneously producing CO and H2 according to the present invention, the alkaline absorption solution can be regenerated by primary electrolysis to produce a portion of pure H2 as a by-product. The H2 obtained can be directly sold as a product, or can be doped with the CO and H2 synthesis gas obtained in the secondary electrolysis cell according to downstream demand to flexibly adjust the carbon-hydrogen ratio in the synthesis gas.

[0077] In addition, the terms "first", "second", etc. in the specification and claims of the present application are not intended to describe a particular order or sequence, but are intended to distinguish between similar objects. In addition, the terms used in this manner may be appropriately interchanged so that the embodiments of the present application described herein may be implemented, for example, in an order other than that described herein.

[0078] The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Those skilled in the art can make various modifications and variations to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention. [Explanation of symbols]

[0079] 10 Carbon dioxide capture device 101 Alkaline solution inlet 102 Target component inlet 103 Carbonate-containing aqueous solution outlet 104 Tower top gas outlet 11. Pump for transporting carbonate-containing aqueous solution 12 Flow control valve 20 1st electrolysis device 201 Carbonate-containing aqueous solution inlet 202 Hydrogen carbonate-containing aqueous solution outlet 203 Hydrogen gas outlet 204 Regenerated alkaline solution outlet 21 1st electrolysis device anolyte transport pump 22 Regenerated alkaline liquid transport pump 23 Anode gas transport fan 30 2nd electrolyzer 31 2nd Electrolysis Device Catholyte Transport Pump 40 Oxygen gas purification equipment 401 Crude oxygen inlet 402 Alkaline absorbent inlet 403 Hydrogen carbonate-containing aqueous solution outlet 404 Tower top exhaust outlet 41 Purification column bottom liquid transport pump 50 Shock absorber 51 External supplementary water transport pipe 60 Cooling device

Claims

1. A method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas, comprising the steps of: Using an alkaline solution to capture carbon dioxide in the target component to obtain a carbonate-containing aqueous solution; performing a first electrolysis process on the carbonate-containing aqueous solution to obtain a bicarbonate-containing aqueous solution and hydrogen gas; and performing a second electrolysis process on the bicarbonate-containing aqueous solution in the presence of a catalyst to obtain carbon monoxide and hydrogen gas. The catalyst is one or more selected from the group consisting of metals, alloys and compounds of Group VIII, Group IB, Group IIB, Group IVA and lanthanoid elements; A method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas.

2. the product of the first electrolysis step further comprises a first crude oxygen gas, the first crude oxygen gas comprising a portion of carbon dioxide; The carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas comprises the steps of: purifying the first crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain pure oxygen gas and the bicarbonate-containing aqueous solution; and performing a first electrolysis process on the bicarbonate-containing aqueous solution to obtain the bicarbonate-containing aqueous solution.

2. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 1.

3. In the first electrolysis step, the electrolytic cell voltage is 1.1 to 4 V, and the current density is 500 to 8000 A / m ２ The carbonate-containing aqueous solution has a pH of 10 to 14, and a carbonate concentration in the carbonate-containing aqueous solution is 1 to 4.5 mol / L.

3. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 1 or 2.

4. the product of the first electrolysis step further comprises regenerated alkaline solution; The carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas comprises the steps of: The method further includes a step of using at least a part of the regenerated alkaline solution and / or the catholyte obtained in at least the second electrolysis step as the alkaline solution in the collection step.

4. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 3.

5. At least a portion of the regenerated alkaline solution is cooled before participating in the collection process.

5. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 4.

6. In the second electrolysis step, the electrolytic cell voltage is 100-220 V, and the current density is 500-10,000 A / m ２ The catalyst loading is 1 to 200 mg / cm ２ The bicarbonate-containing aqueous solution has a pH of 8 to 13, and a bicarbonate concentration in the bicarbonate-containing aqueous solution is 1.5 to 3.8 mol / L.

4. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 3.

7. The operating temperature of the first electrolysis step is 70-95°C, and the operating temperature of the second electrolysis step is 20-90°C.

7. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 6.

8. The catalyst is metal Au, metal Ni, metal Zn, CuPb, CeO ２ and ZnO, and the amount of the catalyst supported is 30 to 80 mg / cm ２ That is, 4. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 3.

9. the product of the second electrolysis step further comprises a second crude oxygen gas, the second crude oxygen gas comprising a portion of carbon dioxide; The carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas comprises the steps of: The method further includes purifying the second crude oxygen gas using a portion of the carbonate-containing aqueous solution to obtain the pure oxygen gas and the bicarbonate-containing aqueous solution.

3. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 2.

10. During the collection process, the pressure is normal pressure, the carbonate-containing aqueous solution has a concentration of 1 to 4.5 mol / L and a pH of 10 to 13.

2. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 1.

11. In the process of purification, in the hydrogen carbonate-containing aqueous solution, the ratio of the molar amount of hydrogen carbonate radicals to the total molar amount of carbonate radicals and hydrogen carbonate radicals is (0.1 to 1):1; 3. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 2.

12. The carbon dioxide capture method capable of simultaneously producing carbon monoxide and hydrogen gas comprises the steps of: and further comprising the step of reintroducing a portion of the carbonate-containing aqueous solution into the collection process.

11. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 10.

13. the molar ratio of carbon monoxide to hydrogen gas obtained in the second electrolysis step is (0.1-1):1; 2. The method for capturing carbon dioxide capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 1.

14. A carbon dioxide capture system capable of co-producing carbon monoxide and hydrogen gas, comprising: A carbon dioxide capture device (10), a first electrolysis device (20), and a second electrolysis device (30), The carbon capture device (10) is provided with an alkaline solution inlet (101), a target component inlet (102) and a carbonate-containing aqueous solution outlet (103); The electrolysis device is provided with a carbonate-containing aqueous solution inlet (201), a hydrogencarbonate-containing aqueous solution outlet (202) and a hydrogen gas outlet (203), and the carbonate-containing aqueous solution outlet (103) and the carbonate-containing aqueous solution inlet (201) are connected to each other. a catalyst is installed inside the second electrolysis device (30); and the first electrolysis device (20) is provided with an inlet for a bicarbonate-containing aqueous solution and a cathode gas outlet, the cathode gas outlet being used to discharge carbon monoxide and hydrogen gas; The catalyst is one or more selected from the group consisting of metals, alloys and compounds of Group VIII, Group IB, Group IIB, Group IVA and lanthanoid elements; A carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas.

15. The first electrolysis device (20) is further provided with a first crude oxygen outlet, The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes an oxygen gas purification device (40), in which a crude oxygen inlet (401), an alkaline absorbent inlet (402), and a hydrogen carbonate-containing aqueous solution outlet (403) are provided, the crude oxygen inlet (401) and the first crude oxygen outlet are connected to each other, and the hydrogen carbonate-containing aqueous solution outlet (403) and the hydrogen carbonate-containing aqueous solution inlet are connected to each other.

15. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 14.

16. The carbonate-containing aqueous solution outlet (103) is connected to the alkaline absorbent inlet (402) and the alkaline solution inlet (101), respectively.

16. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 15.

17. The first electrolysis device (20) further includes a regenerated alkaline solution outlet (204), and the regenerated alkaline solution outlet (204) and the alkaline solution inlet (101) are connected to each other via a regenerated alkaline solution transport pipeline.

16. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 15.

18. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas further includes a buffer device (50) and a cooling device (60), and the buffer device (50) and the cooling device (60) are sequentially installed in the transport pipeline of the regenerated alkaline liquid along the flow direction of the regenerated alkaline liquid.

18. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 17.

19. The second electrolysis device (30) is further provided with a catholyte outlet and a second crude oxygen outlet, the catholyte outlet and the alkaline solution inlet (101) are connected to each other, and the second crude oxygen outlet is connected to the crude oxygen inlet (401).

18. The carbon dioxide capture system capable of simultaneously producing carbon monoxide and hydrogen gas according to claim 17.

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