Co 2 capture method and co 2 capture apparatus based on electrochemical regeneration coupled with hydrogen production

Abstract

The present invention provides a CO2 capture method and CO2 capture apparatus based on electrochemical regeneration coupled with hydrogen production. The method comprises: using an alkaline solution to absorb Co2 from a CO2-containing gas to form a CO2-rich solution; enabling the CO2-rich solution and an acidic solution to undergo acid-base neutralization to obtain a neutralized solution and CO2; and electrolyzing the neutralized solution to obtain a cathodic electrolysis product and an anodic electrolysis product, wherein the cathodic electrolysis product is H2 and an alkaline solution, and the anodic electrolysis product is O2 and an acidic solution. The acidic solution of the present invention can avoid corrosion to apparatuses and devices, and reduce the net energy consumption and net costs of the CO2 capture process.

Description

A CO2 capture method and CO2 capture device coupled with electrochemical regeneration of hydrogen production

[0001] Cross-reference information

[0002] This application claims priority to Chinese Patent Application No. 202411731410.3, filed on November 28, 2024, entitled "A CO2 Capture Method and CO2 Capture Device Coupled with Electrochemical Regeneration of Hydrogen Production", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a CO2 capture method and CO2 capture device coupled with electrochemical regeneration of hydrogen production, belonging to the field of carbon capture technology. Background Technology

[0004] CO2 capture, utilization, and storage (CCUS) technology is one of the most effective means of achieving large-scale carbon emission reduction. Among CO2 capture technologies, solvent-based methods offer advantages such as good separation efficiency and mature, reliable technology; however, they are costly for large-scale CO2 capture. Therefore, reducing energy consumption to lower capture costs has become a research hotspot in solvent-based CO2 capture technology. Besides developing new solvents to reduce energy consumption, optimizing process design can also effectively reduce energy consumption and capture costs.

[0005] CN1232500C discloses a heat recovery method for a regeneration tower used in the regeneration of chemical absorbents. This method fully leverages the advantages of the rich liquid's low boiling point and high heat of vaporization, employing a parallel split-flow approach for heat recovery. This breaks through the traditional "equal heat capacity exchange" paradigm in the field, minimizing heat consumption during the regeneration process. However, it suffers from the drawback of absorbent degradation during thermal regeneration.

[0006] CN113117506A discloses an electrolytic device and method for capturing carbon dioxide from industrial waste gas or air. This process is based on traditional carbon dioxide absorption technology, achieving CO2 capture and regeneration of the CO2 absorbent through electrochemical methods, and also yielding high-purity carbon dioxide products, while simultaneously producing hydrogen and oxygen as byproducts. However, it suffers from the drawback of generating strong acid during electrolysis, which severely corrodes the electrolytic device.

[0007] Although process optimization can significantly reduce capture energy consumption, the following main challenges still exist: (1) Carbon capture absorbents are regenerated by heating, and the absorbents are subject to high-temperature degradation. The process has high energy consumption and high cost, which restricts the large-scale promotion of carbon capture technology; (2) The strong acid of electro-regeneration is highly corrosive to the device, which limits its large-scale application.

[0008] Therefore, it is of great significance to develop a process that can avoid high-temperature degradation of the absorbent while also significantly reducing the net energy consumption and net cost of the entire capture process. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a CO2 capture method and device that couples hydrogen production with electrochemical regeneration. The acidic solution generated by electrolysis in this invention can avoid corrosion of the device and reduce the net energy consumption and net cost of the CO2 capture process.

[0010] To achieve the above objectives, in a first aspect, the present invention provides a CO2 capture method coupled with electrochemical regeneration for hydrogen production, comprising the following steps:

[0011] Step 1: Use an alkaline solution to absorb CO2 from the gas containing CO2, forming a CO2-rich solution;

[0012] Step 2: Neutralize the CO2-rich solution with an acidic solution to obtain a neutralized solution and CO2;

[0013] Step 3: Electrolyze the neutralized solution to obtain cathodic electrolysis products and anodic electrolysis products. The cathodic electrolysis products are H2 and an alkaline solution, and the anodic electrolysis products are O2 and an acidic solution.

[0014] Step 4: The alkaline solution is returned to Step 1 to participate in CO2 absorption, and the acidic solution is returned to Step 2 to participate in acid-base neutralization;

[0015] The acidic solution is selected from one or more of the following: pyruvic acid solution, gluconic acid solution, malonic acid solution, tartaric acid solution, glyceric acid solution, oxaloacetic acid solution, formic acid solution, isopropionic acid solution, isobutyric acid solution, fumaric acid solution, aconitic acid solution, isocitrate solution, and hexanediol diacid solution. The acidic solution may be an aqueous solution of the corresponding acid.

[0016] According to a specific embodiment of the present invention, preferably, in step one, the alkaline solution is a potassium hydroxide solution.

[0017] According to a specific embodiment of the present invention, preferably, in step one, the concentration of the alkaline solution is 0.5-5 mol / L, more preferably 1-3 mol / L.

[0018] According to a specific embodiment of the present invention, preferably, in step one, the flow rate of the CO2-containing gas is 0.3-3 m³ / h. 3 / h, more preferably 1.5-2.5m 3 / h.

[0019] According to a specific embodiment of the present invention, preferably, in step one, the flow rate of the alkaline solution is 0.6-6 L / h, more preferably 3-5 L / h.

[0020] The CO2 absorption process in step one can be carried out in a cyclical manner within the CO2 capture container. The flow rates of the CO2-containing gas and alkaline solution mentioned above refer to the flow rates of the CO2-containing gas and alkaline solution entering the capture container during the absorption process, respectively.

[0021] According to a specific embodiment of the present invention, preferably, in step two, the concentration of the acidic solution is 0.5-5 mol / L, more preferably 1-3 mol / L.

[0022] According to a specific embodiment of the present invention, preferably, in step two, the flow rate ratio of the CO2-rich solution to the acidic solution is 1:(1-3), more preferably 1:2.

[0023] According to a specific embodiment of the present invention, preferably, in step two, the flow rate of the acidic solution is 1.2-7.2 L / h, more preferably 2-5 L / h, and even more preferably 3-4.5 L / h.

[0024] The acid-base neutralization process in step two can be carried out in a suitable reaction vessel. The flow rate ratio of the CO2-rich solution to the acidic solution mentioned above refers to the ratio of the flow rates of the CO2-rich solution and the acidic solution entering the reaction vessel during the acid-base neutralization process.

[0025] According to a specific embodiment of the present invention, preferably, in step three, the initial voltage of the electrolysis is 1.5-5V, and the current density is 100-600mA / cm. 2 More preferably, the initial voltage of the electrolysis is 1.5-2.5V, and the current density is 150-400mA / cm. 2 .

[0026] According to a specific embodiment of the present invention, preferably, in step three, the flow rate of the neutralizing liquid is 0.6-6 L / h, more preferably 3-5 L / h. The electrolysis process in step three can be carried out in a suitable electrolysis device, and the flow rate of the neutralizing liquid refers to the flow rate of the neutralizing liquid entering the electrolysis device.

[0027] According to a specific embodiment of the present invention, preferably, in step three, the concentration of the alkaline solution is 0.5-5 mol / L, more preferably 1-3 mol / L.

[0028] According to a specific embodiment of the present invention, preferably, in step three, the concentration of the acidic solution is 0.5-5 mol / L, more preferably 1-3 mol / L.

[0029] According to a specific embodiment of the present invention, preferably, the concentration of CO2 in the CO2-containing gas is below 60%, more preferably 5%-30%. The components of the CO2-containing gas, in addition to CO2, also include O2, SO2, and NO. x ,water vapor.

[0030] According to a specific embodiment of the present invention, preferably, the method further includes: the CO2 obtained after acid-base neutralization in step two is subjected to a hydrogenation reaction with the H2 of the cathode electrolysis product in step three to obtain various hydrocarbons such as liquid fuels such as methanol, ethanol, gasoline, and kerosene, gaseous components such as methane and syngas, and solid materials such as carbon materials.

[0031] In the technical solution of this invention, steps one, two, three, and four are only for ease of description and are not intended to limit the method of this invention to be performed in such an order. In practice, the method of this invention is performed continuously and cyclically.

[0032] In a preferred embodiment, the CO2 capture method includes:

[0033] Step 1: Set the flow rate to 0.3-3m³ / min. 3 Flue gas with a CO2 concentration of 5%-30% is introduced into the absorption unit at a flow rate of 0.6-6 L / h, while a potassium hydroxide solution with a concentration of 0.5-5 mol / L is introduced from the other side of the device. The CO2 on the gas side enters the solution through a chemical reaction, thus achieving CO2 absorption.

[0034] Step 2: The CO2-absorbed solution and an acidic solution with a concentration of 0.5-5 mol / L are mixed at a flow rate of 1:1-3 and introduced into the neutralization unit, where the flow rate of the acidic solution is 1.2-7.2 L / h. The two react in the neutralization unit to produce high-purity CO2 product gas.

[0035] Step 3: The neutralized solution obtained after the reaction is introduced into the anode of the regeneration unit at a flow rate of 0.6-6 L / h, with a current density of 100-600 mA / cm². 2 Electrolysis is performed at room temperature under constant current conditions, with an initial voltage of 1.5-5V. During electrolysis, high-purity O2 and an acidic solution with a final concentration of about 0.5-5 mol / L are obtained in the anode region, while high-purity H2 and a potassium hydroxide solution with a concentration of about 0.5-5 mol / L are obtained in the cathode region.

[0036] Step 4: The acidic solution obtained in the anode region is returned to the neutralization unit to participate in the neutralization reaction, and the potassium hydroxide solution obtained in the cathode region is returned to the absorption unit to capture CO2.

[0037] In a preferred embodiment, the CO2 capture method further includes:

[0038] Step 1: Set the flow rate to 1.5-2.5m³ / h. 3 Flue gas with a CO2 concentration of 5%-30% is introduced into the absorption unit at a flow rate of 3-5 L / h, while a potassium hydroxide solution with a concentration of 1-3 mol / L is introduced from the other side of the device. The CO2 on the gas side enters the solution through a chemical reaction, thus achieving CO2 absorption.

[0039] Step 2: The CO2-absorbed solution and an acidic solution with a concentration of 1-3 mol / L are mixed at a flow rate of 1:1-3 and introduced into the neutralization unit, where the flow rate of the acidic solution is 2-5 L / h. The two react in the neutralization unit to produce high-purity CO2 product gas.

[0040] Step 3: The neutralized solution obtained after the reaction is introduced into the anode of the regeneration unit at a flow rate of 3-5 L / h, with a current density of 150-400 mA / cm². 2 Electrolysis is performed at room temperature under constant current conditions, with an initial voltage of 1.5-2.5V. During electrolysis, high-purity O2 and an acidic solution with a final concentration of about 1-3 mol / L are obtained in the anode region, while high-purity H2 and a potassium hydroxide solution with a concentration of about 1-3 mol / L are obtained in the cathode region.

[0041] Step 4: The acidic solution obtained in the anode region is returned to the neutralization unit to participate in the neutralization reaction, and the potassium hydroxide solution obtained in the cathode region is returned to the absorption unit to capture CO2.

[0042] In a preferred embodiment, the CO2 capture method further includes:

[0043] Step 1: Set the flow rate to 1.5-2.5m³ / h. 3 Flue gas with a CO2 concentration of 5%-30% is introduced into the absorption unit at a flow rate of 3-5 L / h, while a potassium hydroxide solution with a concentration of 1-3 mol / L is introduced from the other side of the device. The CO2 on the gas side enters the solution through a chemical reaction, thus achieving CO2 absorption.

[0044] Step 2: The CO2-absorbed solution and a 1-3 mol / L pyruvate solution are mixed at a flow rate of 1:2 and introduced into the neutralization unit. The flow rate of the acidic solution is 3-4.5 L / h. The two react in the neutralization unit to produce high-purity CO2 product gas.

[0045] Step 3: Pass the potassium pyruvate solution obtained after the reaction into the anode of the regeneration unit at a flow rate of 3-5 L / h, with a current density of 150-400 mA / cm². 2Electrolysis was performed at room temperature under constant current conditions, with an initial voltage of 1.5-2.5V. During the electrolysis process, high-purity O2 and a pyruvate solution with a final concentration of about 1-3 mol / L were obtained in the anode region, while high-purity H2 and a potassium hydroxide solution with a concentration of about 1-3 mol / L were obtained in the cathode region.

[0046] Step 4: The pyruvate solution obtained in the anode region is returned to the neutralization unit to participate in the neutralization reaction, and the potassium hydroxide solution obtained in the cathode region is returned to the absorption unit to capture CO2.

[0047] Secondly, the present invention also provides a CO2 capture device for the above-described electrochemical regeneration method of coupled hydrogen production, comprising:

[0048] The absorption unit has a CO2-containing gas inlet, an alkaline solution inlet, a CO2-rich solution outlet, and a waste gas outlet; the absorption unit is used to allow the alkaline solution to absorb CO2 from the CO2-containing gas, forming a CO2-rich solution;

[0049] The neutralization unit has a CO2-rich solution inlet, an acidic solution inlet, a neutralized solution outlet, and a CO2 outlet; the neutralization unit is used to neutralize the CO2-rich solution with the acidic solution to obtain a neutralized solution and CO2.

[0050] The regeneration unit has a neutralizing liquid inlet, an H2 outlet, an alkaline solution outlet, an O2 outlet, and an acidic solution outlet; the regeneration unit is used to electrolyze the neutralizing liquid, obtaining H2 and an alkaline solution at the cathode and obtaining O2 and an acidic solution at the anode;

[0051] The CO2-rich liquid outlet of the absorption unit is connected to the CO2-rich liquid inlet of the neutralization unit.

[0052] The neutralization liquid outlet of the neutralization unit is connected to the neutralization liquid inlet of the regeneration unit;

[0053] The acidic solution inlet of the neutralization unit is connected to the acidic solution outlet of the regeneration unit;

[0054] The alkaline solution outlet of the regeneration unit is connected to the alkaline solution inlet of the absorption unit.

[0055] According to a specific embodiment of the present invention, preferably, the absorption unit is used for contacting the CO2-containing gas with an alkaline solution, and the equipment used in the absorption unit can be, for example, a CO2 absorption tower.

[0056] According to a specific embodiment of the present invention, the CO2-containing gas inlet of the absorption unit is used to input the CO2-containing gas that needs to be captured, and the waste gas outlet is used to discharge the waste gas generated during the absorption process.

[0057] According to a specific embodiment of the present invention, preferably, the neutralization unit is used for the acid-base neutralization reaction between the CO2-rich solution and the acidic solution, and the equipment used in the neutralization unit can be, for example, a neutralization reaction vessel.

[0058] According to a specific embodiment of the present invention, the CO2 outlet of the neutralization unit is used to discharge the desorbed CO2 gas.

[0059] According to a specific embodiment of the present invention, preferably, the regeneration unit is used to electrolyze the neutralized liquid.

[0060] According to a specific embodiment of the present invention, preferably, the regeneration unit is an electrolysis device, the electrolysis device having a regeneration cathode chamber and a regeneration anode chamber; a cation membrane is disposed between the regeneration cathode chamber and the regeneration anode chamber; an electrolytic cathode is disposed in the regeneration cathode chamber, and an electrolytic anode is disposed in the regeneration anode chamber; the regeneration cathode chamber has an alkaline solution outlet and an H2 outlet; the regeneration anode chamber has an acidic solution outlet, a neutralization liquid inlet, and an O2 outlet.

[0061] According to a specific embodiment of the present invention, preferably, the regeneration anode chamber of the regeneration unit is provided with an anode electrolyte circulation pipeline, and the regeneration cathode chamber of the regeneration unit is provided with a cathode electrolyte circulation pipeline.

[0062] According to a specific embodiment of the present invention, the H2 outlet and O2 outlet of the regeneration unit are used to output H2 and O2 generated during the electrolysis process, respectively.

[0063] According to a specific embodiment of the present invention, preferably, the CO2 capture device further includes: a carbon hydrogenation unit having an H2 inlet and a CO2 inlet; the carbon hydrogenation unit is used to perform a hydrogenation reaction between the CO2 obtained by acid-base neutralization and the H2 obtained by cathode electrolysis to produce hydrocarbons.

[0064] The CO2 inlet of the carbon hydrogenation unit is connected to the CO2 outlet of the neutralization unit; the H2 inlet of the carbon hydrogenation unit is connected to the H2 outlet of the regeneration unit.

[0065] According to a specific embodiment of the present invention, preferably, the equipment used in the carbon hydrogenation unit can be, for example, a CO2 hydrogenation high-pressure reactor.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] This invention employs an electrochemical regeneration carbon capture method that combines room-temperature absorption with coupled hydrogen production, achieving regeneration while simultaneously preparing hydrocarbons through carbon hydrogenation. The acidic solution generated by electrolysis in this invention avoids corrosion of the equipment, significantly improving the economics and environmental friendliness of the process, and reducing the net energy consumption and net cost of the entire CO2 capture process. Attached Figure Description

[0068] Figure 1 is a process flow diagram of the present invention.

[0069] The attached diagram shows the following: 1. Absorption unit; 2. Neutralization unit; 31. Regenerated cathode chamber; 32. Regenerated anode chamber; 33. Cation membrane; 34. Cathode electrolyte circulation line; 35. Anode electrolyte circulation line; 4. Carbon hydrogenation unit. Detailed Implementation

[0070] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0071] As shown in Figure 1, the CO2 capture device includes:

[0072] Absorption unit 1 has a CO2 gas inlet, an alkaline solution inlet, a CO2-rich solution outlet, and a waste gas outlet;

[0073] Neutralization unit 2 has a CO2-rich solution inlet, an acidic solution inlet, a neutralized solution outlet, and a CO2 outlet;

[0074] The electrolysis apparatus includes a regeneration cathode chamber 31 and a regeneration anode chamber 32;

[0075] The regeneration cathode chamber 31 has an alkaline solution outlet and an H2 outlet;

[0076] The regeneration anode chamber 32 has an acidic solution outlet, a neutralization solution inlet, and an O2 outlet;

[0077] Carbon hydrogenation unit 4 has an H2 inlet and a CO2 inlet;

[0078] The CO2-rich liquid outlet of absorption unit 1 is connected to the CO2-rich liquid inlet of neutralization unit 2;

[0079] The neutralization liquid outlet of neutralization unit 2 is connected to the neutralization liquid inlet of regeneration anode chamber 32;

[0080] The acidic solution inlet of neutralization unit 2 is connected to the acidic solution outlet of regeneration anode chamber 32;

[0081] The alkaline solution outlet of the regenerating cathode chamber 31 is connected to the alkaline solution inlet of the absorption unit 1;

[0082] A cation membrane 33 is disposed between the regeneration cathode chamber 31 and the regeneration anode chamber 32;

[0083] The regenerated cathode chamber 31 is also equipped with a cathode electrolyte circulation pipeline 34, and the regenerated anode chamber 32 is also equipped with an anode electrolyte circulation pipeline 35;

[0084] The CO2 inlet of carbon hydrogenation unit 4 is connected to the CO2 outlet of neutralization unit 2;

[0085] The H2 inlet of the carbon hydrogenation unit 4 is connected to the H2 outlet of the regeneration cathode chamber 31.

[0086] Example 1

[0087] This embodiment provides a CO2 capture method, which is performed using the apparatus shown in Figure 1. The method includes:

[0088] Step 1: Set the flow rate to 1m 3 Flue gas with a CO2 concentration of 13% per hour is introduced into the absorption unit, while a 3 mol / L potassium hydroxide solution is introduced from the other side of the device at a flow rate of 2 L / h. The CO2 from the gaseous side enters the solution through a chemical reaction, achieving CO2 absorption with a capture rate of 98%.

[0089] Step 2: The CO2-absorbed solution and a 3 mol / L pyruvate solution are mixed at a flow rate of 1:2 and introduced into the neutralization unit, where the pyruvate solution flows at a flow rate of 3 L / h. The two react in the neutralization unit to produce high-purity CO2 product gas, with a CO2 desorption rate of approximately 90%.

[0090] Step 3: Pass the potassium pyruvate solution obtained after the reaction into the anode of the regeneration unit (electrolysis device) at a current density of 200 mA / cm². 2 Electrolysis was performed at room temperature under constant current conditions, with an initial voltage of 1.9V. During the electrolysis process, high-purity O2 and a pyruvate solution with a final concentration of approximately 3 mol / L were obtained in the anode region, while high-purity H2 and a potassium hydroxide solution with a concentration of approximately 3 mol / L were obtained in the cathode region. The electrolysis efficiency was approximately 95%.

[0091] Step 4: The pyruvate solution obtained in the anode region is returned to the neutralization unit to participate in the neutralization reaction, and the potassium hydroxide solution obtained in the cathode region is returned to the absorption unit to capture CO2.

[0092] Calculations show that the net energy consumption for the entire capture process is 1.48 GJ / t CO2, and the net capture cost is 150 yuan / t CO2.

[0093] Example 2

[0094] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0095] In step one, a potassium hydroxide solution with a flow rate of 1 L / h and a concentration of 3 mol / L is introduced from the other side of the device.

[0096] Example 3

[0097] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0098] In step one, a potassium hydroxide solution with a flow rate of 3 L / h and a concentration of 3 mol / L is introduced from the other side of the device.

[0099] Example 4

[0100] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0101] In step one, a potassium hydroxide solution with a flow rate of 2 L / h and a concentration of 1 mol / L is introduced from the other side of the device.

[0102] Example 5

[0103] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0104] In step one, a potassium hydroxide solution with a flow rate of 2 L / h and a concentration of 2 mol / L is introduced from the other side of the device.

[0105] Example 6

[0106] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0107] In step two, a pyruvate solution with a concentration of 1 mol / L is used in the neutralization unit.

[0108] Example 7

[0109] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0110] In step two, a 2 mol / L pyruvate solution is used in the neutralization unit.

[0111] Example 8

[0112] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0113] In step two, a pyruvate solution with a flow rate of 2 L / h and a concentration of 3 mol / L is introduced into the neutralization unit.

[0114] Example 9

[0115] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0116] In step two, a pyruvate solution with a flow rate of 5 L / h and a concentration of 3 mol / L is introduced into the neutralization unit.

[0117] Example 10

[0118] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0119] In step two, a 3 mol / L gluconic acid solution is used in the neutralization unit.

[0120] Example 11

[0121] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0122] In step two, a 3 mol / L malonic acid solution is used in the neutralization unit.

[0123] Example 12

[0124] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0125] In step two, a 3 mol / L tartaric acid solution is used in the neutralization unit.

[0126] Example 13

[0127] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0128] In step two, a 3 mol / L glyceric acid solution is used in the neutralization unit.

[0129] Example 14

[0130] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0131] In step two, the CO2-absorbed solution and the acid solution are mixed at a 1:1 flow rate and enter the neutralization unit.

[0132] Example 15

[0133] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0134] In step two, the CO2-absorbed solution and the acid solution are mixed at a flow rate of 1:3 and then enter the neutralization unit.

[0135] Example 16

[0136] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0137] In step three, the current density is 100 mA / cm². 2 .

[0138] Example 17

[0139] This embodiment provides a CO2 capture method, which differs from Embodiment 1 only in that:

[0140] In step three, the current density is 300 mA / cm². 2 .

[0141] Comparative Example 1

[0142] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0143] In step one, a potassium hydroxide solution with a concentration of 3 mol / L is introduced from the other side of the apparatus using a flow rate of 0.5 L / h.

[0144] Comparative Example 2

[0145] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0146] In step one, a potassium hydroxide solution with a concentration of 0.1 mol / L is introduced from the other side of the device at a flow rate of 1 L / h.

[0147] Comparative Example 3

[0148] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0149] In step one, the use of NaOH solution will cause a significant decrease in the solubility of electrolytes in the rich absorbent solution, resulting in precipitation and making it impossible to regenerate part of the rich absorbent solution.

[0150] Comparative Example 4

[0151] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0152] In step two, a pyruvate solution with a concentration of 0.1 mol / L is used in the neutralization unit.

[0153] Comparative Example 5

[0154] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0155] In step two, a pyruvate solution of 0.5 L / h is introduced into the neutralization unit.

[0156] Comparative Example 6

[0157] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0158] In step two, the use of glycine will reduce the electrolysis efficiency and CO2 desorption efficiency.

[0159] Comparative Example 7

[0160] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0161] In step two, the CO2-absorbed solution and the acid solution are mixed at a flow rate of 2:1 and enter the neutralization unit.

[0162] Comparative Example 8

[0163] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0164] In step three, the current density is 50 mA / cm². 2 .

[0165] Comparative Example 9

[0166] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0167] In step three, the anode region yields high-purity O2 and a final pyruvate solution of approximately 0.1 mol / L.

[0168] Comparative Example 10

[0169] This comparative example provides a CO2 capture method, which differs from Example 1 only in that:

[0170] In step three, high-purity H2 and a 0.1 mol / L potassium hydroxide solution are obtained in the cathode region.

[0171] The calculation methods for the parameters involved in Table 1 are as follows:

[0172] CO2 capture rate = (CO2 captured / total CO2) × 100%;

[0173] CO2 desorption rate = (amount of desorbed CO2 / amount of captured CO2) × 100%;

[0174] Electrolysis efficiency = (Hydrogen production charge consumption / Total electrolysis charge) × 100%;

[0175] Net energy consumption = Total energy consumption - Hydrogen production energy consumption = Total electrolysis power × Total electrolysis time - Hydrogen production energy consumption;

[0176] Total energy consumption for electrolysis = Total power for electrolysis × Total time for electrolysis;

[0177] Hydrogen production energy consumption = total hydrogen production power × total hydrogen production time;

[0178] Net capture cost = Net energy consumption × Unit energy price / 0.7 (including 30% depreciation).

[0179] Table 1 shows the relevant results of CO2 capture rate, CO2 desorption rate, electrolysis efficiency, net energy consumption and net cost for the examples and comparative examples.

[0180] Table 1

[0181] In Example 1, the flow rate of the potassium hydroxide solution introduced into the absorption unit in step one was 2 L / h, resulting in a high CO2 capture rate and low cost. In contrast, the flow rate of the potassium hydroxide solution in Comparative Example 1 was 0.5 L / h, leading to a low capture rate and high cost. This demonstrates that excessively low flow rates of the alkaline solution into the absorption unit reduce the amount of CO2 processed per unit time. Using an acidic solution generated by electrolysis avoids corrosion of the equipment and reduces the net energy consumption and net cost of the entire CO2 capture process.

[0182] In Comparative Example 2, the concentration of potassium hydroxide solution in step one was 0.1 mol / L. Compared with the concentration of potassium hydroxide in Example 1, which was 3 mol / L, the lower concentration of alkaline solution resulted in a significant reduction in the amount of CO2 processed per unit time, leading to poor CO2 capture rate and high cost.

[0183] Comparative Example 3 used an alkaline sodium hydroxide solution. Compared with Example 1, which used a potassium hydroxide solution, it had a poorer CO2 capture rate, a poorer desorption rate, lower electrolysis efficiency, and higher cost. This is because some of the solutes in the solution that absorbs CO2 exist in the solution in the form of precipitates, which greatly reduces the solubility of the electrolyte and generates precipitates, making it impossible for them to participate in subsequent reactions.

[0184] In Comparative Example 4, the concentration of the pyruvate solution used in step two was 0.1 mol / L. Compared with the concentration of 3 mol / L of the pyruvate solution in Example 1, the concentration of the acidic solution in Comparative Example 4 was too low to desorb the absorbed CO2, resulting in poor CO2 desorption rate, low electrolysis efficiency, and high cost.

[0185] Compared with Example 1, in Comparative Example 5, when the flow rate of potassium hydroxide solution in step 2 is too low at 0.5 L / h, the absorbed CO2 cannot be desorbed, resulting in poor CO2 capture rate and high cost.

[0186] Comparative Example 6 uses a glycine solution. Compared with Example 1 which uses a pyruvate solution, the amount of absorbed CO2 that cannot be desorbed will result in a decrease in electrolysis efficiency, a decrease in CO2 desorption efficiency, and a poorer glycine regeneration effect.

[0187] In Comparative Example 7, the flow rate ratio of the solution after CO2 absorption to the acidic solution in step two was 2:1. Compared with Example 1, where the flow rate ratio of the solution after CO2 absorption to the acidic solution was 1:2, the absorbed CO2 could not be desorbed, resulting in poor CO2 desorption rate, low electrolysis efficiency, and high cost.

[0188] The current density of Comparative Example 8 is 50 mA / cm². 2 Compared with Example 1, the neutralization solution cannot be efficiently regenerated to obtain acidic solution and potassium hydroxide solution, resulting in low CO2 electrolysis efficiency and high cost.

[0189] Compared with Example 1, in Comparative Example 9, the concentration of the final pyruvate solution obtained in the anode region in step 3 is about 0.1 mol / L. Since the neutralization solution cannot be efficiently regenerated to obtain acidic solution and potassium hydroxide solution, it will result in poor CO2 capture rate, poor desorption rate, low electrolysis efficiency and high cost.

[0190] In Comparative Example 10, a 0.1 mol / L potassium hydroxide solution was obtained in the cathode region in step 3. Compared with the 3 mol / L potassium hydroxide solution obtained in the cathode region of Example 1, the neutralization solution could not be efficiently regenerated to obtain an acidic solution and a potassium hydroxide solution, resulting in poor CO2 capture rate, poor desorption rate, low electrolysis efficiency, and high cost.

[0191] The present invention can achieve a maximum CO2 capture rate and electrolysis efficiency of 98%, a maximum CO2 desorption rate of 90%, and the net energy consumption of the entire capture process can be controlled at 1.4-1.9 GJ / t CO2, and the net cost of capture can be controlled at 140-190 yuan / t CO2.

Claims

1. A process for CO2 capture with coupled electrochemical regeneration of hydrogen, wherein, The method comprises the following steps: Step 1: absorbing CO2 in the CO2-containing gas by using an alkaline solution to form a CO2-rich solution; Step 2: neutralizing the CO2-rich solution with an acidic solution to obtain a neutralized solution and CO2; Step 3: electrolyzing the neutralized solution to obtain a cathode electrolysis product and an anode electrolysis product, wherein the cathode electrolysis product is H2 and the alkaline solution, and the anode electrolysis product is O2 and the acidic solution; Step 4: returning the alkaline solution to the step 1 to participate in the absorption of CO2, and returning the acidic solution to the step 2 to participate in the acid-base neutralization; The acidic solution is selected from one or a combination of two or more of the following: pyruvic acid solution, gluconic acid solution, malonic acid solution, tartaric acid solution, glyceric acid solution, oxalacetic acid solution, formic acid solution, isopropionic acid solution, isobutyric acid solution, fumaric acid solution, aconitic acid solution, isocitric acid solution, and hexanediol diacid solution.

2. The CO2 capture method of claim 1, wherein, In the step 1, the alkaline solution is a potassium hydroxide solution.

3. The CO2 capture method of claim 1, wherein, In the step 1, the concentration of the alkaline solution is 0.5-5 mol / L.

4. The CO2 capture method of claim 1, wherein, In step one, the flow rate of the gas containing CO2 is 0.3-3 m 3 / h.

5. The CO2 capture method of claim 1, wherein, In the step 1, the flow rate of the alkaline solution is 0.6-6 L / h.

6. The CO2 capture method of claim 1, wherein, In the step 2, the concentration of the acidic solution is 0.5-5 mol / L.

7. The CO2 capture method of claim 1, wherein, In the step 2, the flow rate ratio of the CO2-rich solution to the acidic solution is 1:(1-3).

8. The CO2 capture method of claim 1, wherein, In the step 2, the flow rate of the acidic solution is 1.2-7.2 L / h.

9. The CO2 capture method of claim 1, wherein, In step three, the initial voltage of the electrolysis is 1.5-5 V, and the current density is 100-600 mA / cm 2 .

10. The CO2 capture method of claim 1, wherein, In the step 3, the flow rate of the neutralized solution is 0.6-6 L / h.

11. The CO2 capture method of claim 1, wherein, In the step 3, the concentration of the alkaline solution is 0.5-5 mol / L.

12. The CO2 capture method of claim 1, wherein, In step 3, the concentration of the acidic solution is 0.5-5 mol / L.

13. The CO2 capture method of claim 1, wherein, The concentration of CO2 in the CO2-containing gas is 60% or less.

14. The CO2 capture method of claim 1, wherein, The method further comprises: performing a hydrogenation reaction between the CO2 obtained after the acid-base neutralization in the step 2 and the H2 in the cathode electrolysis product in the step 3 to prepare a hydrocarbon.

15. A CO2 capture device for the CO2 capture method coupled with hydrogen production and electrochemical regeneration of claim 1-14, comprising: an absorption unit having a CO2-containing gas inlet, an alkaline solution inlet, a CO2-rich solution outlet, and a waste gas outlet; a neutralization unit having a CO2-rich solution inlet, an acidic solution inlet, a neutralized solution outlet, and a CO2 outlet; a regeneration unit having a neutralized solution inlet, an H2 outlet, an alkaline solution outlet, an O2 outlet, and an acidic solution outlet; the CO2-rich solution outlet of the absorption unit is connected to the CO2-rich solution inlet of the neutralization unit; the neutralized solution outlet of the neutralization unit is connected to the neutralized solution inlet of the regeneration unit; the acidic solution inlet of the neutralization unit is connected to the acidic solution outlet of the regeneration unit; the alkaline solution outlet of the regeneration unit is connected to the alkaline solution inlet of the absorption unit.

16. The CO2 capture device of claim 15, wherein, The device further comprises: a carbon hydrogenation unit having an H2 inlet and a CO2 inlet; the CO2 inlet of the carbon hydrogenation unit is connected to the CO2 outlet of the neutralization unit; the H2 inlet of the carbon hydrogenation unit is connected to the H2 outlet of the regeneration unit.

17. The CO2 capture device of claim 15, wherein, The regeneration unit is an electrolysis device, which has a regeneration cathode chamber and a regeneration anode chamber; A cation membrane is arranged between the regeneration cathode chamber and the regeneration anode chamber; An electrolysis cathode is arranged in the regeneration cathode chamber, and an electrolysis anode is arranged in the regeneration anode chamber; The regeneration cathode chamber has the alkaline solution outlet and an H2 outlet; The regeneration anode chamber has the acid solution outlet, a neutralizing liquid inlet, and an O2 outlet.

18. The CO2 capture device of claim 17, wherein, The regeneration anode chamber of the regeneration unit is provided with an anode electrolyte circulating pipeline, and the regeneration cathode chamber of the regeneration unit is provided with a cathode electrolyte circulating pipeline.

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