Electrochemically Assisted Method and System for Simultaneous Hydrogen and Magnesium Carbonate Production from CO2 in Seawater Mineralization

Abstract

The present disclosure provides a method and system for electrochemically assisted seawater mineralization of CO2 for simultaneous hydrogen production and basic magnesium carbonate. The method comprises: separating an anode chamber and a cathode chamber by a selective ion exchange membrane, adding concentrated seawater to the cathode chamber, introducing CO2-containing gas into the cathode chamber or a mineralization reaction zone connected with the cathode chamber, generating OH ‑ and hydrogen by water electrolysis reaction, reacting OH ‑ with CO2 and Mg 2+ to form a solid precipitate of magnesium-based compounds; in the anode chamber, a chlorine evolution reaction occurs to produce chlorine gas as a byproduct; hydrogen produced in the cathode is separated from the electrolyte in a gas-liquid separator, and the hydrogen is condensed, dried, deoxygenated and purified to obtain hydrogen gas product; the cathode effluent containing solid precipitate is separated in a solid-liquid separation unit, and the separated wet solid is washed and dried to obtain basic magnesium carbonate product. The process of the present disclosure has high flexibility and can be adapted to various magnesium sources such as pure chemicals and industrial waste liquid.

Description

Technical Field

[0001] This disclosure pertains to the technical field of seawater mineralization and magnesium-based compound production, specifically relating to an electrochemically assisted method and system for simultaneous hydrogen and magnesium carbonate production from CO2 produced by seawater mineralization. Background Technology

[0002] Against the backdrop of climate change, carbon dioxide (CO2) emission reduction and clean energy production are major global challenges. Current CO2 mineralization and storage technologies primarily utilize natural alkaline minerals or industrial waste, but these generally suffer from slow reaction rates, high energy consumption, and the need for additional chemical alkalis (such as NaOH). On the other hand, water electrolysis for hydrogen production, as a green hydrogen production route, faces economic bottlenecks due to high power consumption and low added value of oxygen. Traditional water electrolysis produces hydrogen gas and hydroxide ions (OH-) at the cathode. - Oxygen is produced at the anode. If the OH- produced at the cathode can be effectively utilized... - Driving CO2 mineralization can simultaneously achieve negative CO2 emissions, high-value-added mineral production, and low-cost hydrogen production.

[0003] However, this coupling process faces multiple technical bottlenecks, such as the challenge of matching reaction kinetics and the challenges of OH generated during electrolysis. - Concentration and distribution depend on the gas-liquid mass transfer and absorption of CO2, as well as its subsequent interaction with Mg. 2+ The mineral precipitation kinetics of plasma must be precisely matched; otherwise, OH- ions are highly likely to form. - Local overconcentration can lead to the production of low-value magnesium hydroxide, or insufficient CO2 absorption, resulting in low reaction efficiency and poor product purity. Secondly, there is a lack of electrode and system design, with a shortage of electrolytic cell configurations and electrode materials specifically designed for coupled reactions to promote gas-liquid-solid three-phase mass transfer, suppress side reactions, and achieve effective product separation. Product separation and purification present challenges, requiring the simultaneous and efficient separation of hydrogen products and solid magnesium compounds, while managing anolyte products (such as Cl2, O2, or soluble ions) to avoid cross-contamination. Furthermore, there is insufficient raw material adaptability: existing processes require high raw material purity, making it difficult to directly and efficiently process low-grade magnesium sources (such as seawater brine and olivine leachate), as impurity ions in these sources can interfere with the electrolysis and precipitation processes.

[0004] To address the above problems, this invention proposes an electrochemically assisted method for simultaneous hydrogen production and basic magnesium carbonate production from CO2 mineralization in seawater. Summary of the Invention

[0005] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide an electrochemically assisted method and system for simultaneous hydrogen production and basic magnesium carbonate production from seawater mineralization of CO2.

[0006] One aspect of this disclosure provides an electrochemically assisted method for simultaneous hydrogen production and basic magnesium carbonate production from seawater mineralization of CO2, the method comprising: The anode chamber and cathode chamber are separated by a selective ion exchange membrane. Concentrated seawater is added to the cathode chamber, and CO2-containing gas is introduced into the cathode chamber or a mineralization reaction zone connected to the cathode chamber. The cathode is made of a material with high specific surface area and high hydrogen evolution activity, and OH- is generated through water electrolysis. - and hydrogen, OH - With CO2 and Mg 2+ The reaction forms a solid precipitate of magnesium-based compounds; In the anode chamber, a chlorine evolution reaction occurs, producing chlorine gas as a byproduct; The hydrogen produced at the cathode is separated from the electrolyte in a gas-liquid separator. The hydrogen is then condensed, dried, and purified to obtain the hydrogen product. The cathode effluent rich in solid precipitates enters the solid-liquid separation unit for separation. The separated wet solids are washed and dried to obtain basic magnesium carbonate product.

[0007] Optionally, the cathode may be made of platinum-plated titanium mesh, nickel foam, or carbon-based material.

[0008] Optionally, the selective ion exchange membrane is an AEM anion exchange membrane.

[0009] Optionally, the current density in the cathode chamber is 300-500 mA / cm². 2 .

[0010] Optionally, the temperature of the cathode chamber is 40-55°C.

[0011] Optionally, the CO2-containing gas is power plant flue gas, lime kiln gas, air, or pure CO2.

[0012] Optionally, when the CO2-containing gas is power plant flue gas, lime kiln gas, or air, the CO2 concentration is 0.04-15 vol.%.

[0013] In another aspect, this disclosure proposes an electrochemically assisted system for simultaneous hydrogen production and basic magnesium carbonate production from CO2 mineralization in seawater, the system comprising a cathode chamber and an anode chamber, and a selective ion exchange membrane separating the cathode chamber and the anode chamber; wherein, The cathode chamber is also provided with an inlet for introducing concentrated seawater, a solid outlet for separating magnesium-based compounds, and a hydrogen outlet for discharging hydrogen. The anode chamber is equipped with a chlorine outlet for discharging chlorine products.

[0014] This disclosure presents a method and system for electrochemically assisted seawater mineralization of CO2 to simultaneously produce hydrogen and basic magnesium carbonate. The method includes: separating an anode chamber and a cathode chamber via a selective ion exchange membrane; adding concentrated seawater to the cathode chamber; introducing CO2-containing gas into the cathode chamber or a mineralization reaction zone connected to the cathode chamber; using a highly active hydrogen evolution material as the cathode material; and generating OH- through water electrolysis. - and hydrogen, OH - With CO2 and Mg 2+ The reaction forms a solid precipitate of magnesium-based compounds. In the anode chamber, a chlorine evolution reaction occurs, producing chlorine gas as a byproduct. Hydrogen gas generated at the cathode is separated from the electrolyte in a gas-liquid separator. The hydrogen gas is condensed, dried, and deoxygenated to obtain hydrogen product. The cathode effluent rich in solid precipitate enters a solid-liquid separation unit for further separation. The separated wet solids are washed and dried to obtain basic magnesium carbonate product. The process design disclosed herein is highly flexible and adaptable to various magnesium sources, ranging from pure chemicals to industrial waste liquids (brine, mineral leachate). Attached Figure Description

[0015] Figure 1 A flowchart illustrating an electrochemically assisted method for simultaneous hydrogen production and basic magnesium carbonate production from CO2 mineralization in seawater, as described in a specific embodiment of this disclosure. Figure 2 This is a schematic diagram of an electrochemically assisted system for simultaneous hydrogen production from CO2 and basic magnesium carbonate from seawater mineralization, as described in a specific embodiment of this disclosure. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0017] As shown in Figure 1, one aspect of this disclosure provides a method S100 for electrochemically assisted seawater mineralization of CO2 to simultaneously produce hydrogen and basic magnesium carbonate, specifically including the following steps S110~S140: S110. The anode chamber and cathode chamber are separated by a selective ion exchange membrane. Concentrated seawater is added to the cathode chamber, and CO2-containing gas is introduced into the cathode chamber or a mineralization reaction zone connected to the cathode chamber. The cathode can be made of a material with high specific surface area and high hydrogen evolution activity. The water electrolysis reaction produces OH-. - and hydrogen, OH - With CO2 and Mg 2+ The reaction forms a solid precipitate of magnesium-based compounds.

[0018] In step S110, a dedicated membrane electrolysis system is first constructed. The anode chamber is separated from the cathode chamber by a selective ion exchange membrane, preferably an AEM anion exchange membrane. The ion exchange membrane (AEM) effectively isolates the cathode and anode chambers, preventing cross-contamination of products (such as Cl2 entering the cathode chamber to oxidize H2, or Mg(OH)2 precipitating into the anode chamber), while allowing specific ions (such as Cl2) to enter the cathode chamber to oxidize H2, or Mg(OH)2 precipitate to enter the anode chamber). - OH - They migrate to maintain charge balance.

[0019] In step S110, concentrated seawater after evaporation is used as the cathode electrolyte. The feed solution can be pretreated (e.g., preliminary filtration, pH adjustment) to remove large suspended particles or some impurities. Then, the treated seawater is pumped into the cathode chamber of the membrane electrolyzer as the cathode electrolyte. Simultaneously, a CO2-containing gas (such as power plant flue gas, lime kiln gas, or air) is introduced into the cathode chamber or the connected mineralization reaction zone. Thus, on the one hand, the cathode reaction reduces water to generate hydrogen (H2) and hydroxide ions (OH-). - OH generated in the cathode region - It rapidly raises the local pH, specifically through the following reaction: 2H₂O + 2e⁻ - → H2↑ + 2OH - On the other hand, it promotes the rapid hydration and dissolution of the introduced CO2 (or CO2-containing gas) in the alkaline microenvironment, converting it into carbonate (CO3-). 2- ), and then react with Mg in seawater 2+ The reaction produces magnesium-based compound precipitates of magnesium hydroxide [Mg(OH)2] or basic magnesium carbonate [xMgCO3·yMg(OH)2·zH2O], which grow and precipitate under electrolyte circulation or external stirring / fluidization conditions.

[0020] In some preferred embodiments, the cathode can preferably be a platinum-titanium mesh, nickel foam, or carbon-based material. These materials can create high-pH localized regions on the electrode surface, significantly promoting CO2 dissolution, hydration, and subsequent carbonate generation and precipitation reactions. The high specific surface area helps increase active sites and enhance mass transfer. For example, foam or mesh structures can provide a larger reaction area, loading more catalytic sites per unit area and increasing the reaction rate. The porous structure facilitates electrolyte permeation and rapid gas desorption, preventing bubbles from covering the electrode surface and maintaining a continuous and efficient reaction. Simultaneously, the high activity significantly reduces the additional voltage required for hydrogen evolution, ensuring that electrons are preferentially used for hydrogen production.

[0021] In some preferred embodiments, the current density in the cathode chamber is 300-500 mA / cm². 2 .

[0022] In some preferred embodiments, the temperature of the cathode chamber is 40-55°C.

[0023] In some preferred embodiments, the CO2-containing gas is power plant flue gas, lime kiln gas, air, or pure CO2.

[0024] In some preferred embodiments, when the CO2-containing gas is power plant flue gas, lime kiln gas, or air, the CO2 concentration is 0.04-15 vol.%. It should be understood that when the CO2-containing gas is pure CO2, the CO2 concentration is 100 vol.%.

[0025] This embodiment, through electrochemical parameter regulation and reaction sequence design, can directly process raw materials containing impurities and produce high-purity products, thus expanding the application scenarios and economic competitiveness of the technology.

[0026] S120 In the anode chamber, a chlorine evolution reaction occurs, producing chlorine gas as a byproduct.

[0027] In step S120, a controlled oxidation reaction occurs at the anode (first chloride ions are oxidized to produce chlorine, then water is oxidized to produce oxygen), generating chlorine gas as a byproduct. The specific reaction formula is as follows: 2Cl - →Cl2↑+2e - At the same time, the ion exchange membrane shell prevents harmful substances from diffusing into the cathode chamber.

[0028] S130. Online separation and purification of products: The hydrogen gas generated at the cathode is separated from the electrolyte in a gas-liquid separator. After condensation, drying, and deoxygenation purification, hydrogen products are obtained.

[0029] S140, Solid product separation: The cathode effluent rich in solid precipitates enters the solid-liquid separation unit for separation. The separated wet solids are washed and dried to obtain basic magnesium carbonate product.

[0030] In step S140, the solid-liquid separation unit may be a hydrocyclone, settling tank, filter or centrifuge.

[0031] It should be understood that the method of this embodiment also includes: electrolyte regeneration and recycling, that is, the clear liquid after solid separation (rich in unreacted Mg) 2+ The electrolyte can be returned to the cathode chamber for recycling, and fresh magnesium and water can be added as needed to maintain steady-state operation.

[0032] It should also be understood that the anode products should be safely collected and processed in this embodiment. For example, chlorine gas can be cooled and dried as a chemical raw material.

[0033] It should be noted that the yield and type of the product obtained in step S140 are related to the current density and CO2 concentration. Higher current density results in a higher solid yield, and higher CO2 concentration results in a higher yield of basic magnesium carbonate. In other words, high CO2 concentration is beneficial for obtaining basic magnesium carbonate, and high current density is beneficial for increasing the solid yield. Under other conditions, the obtained solid may be Mg(OH)2, which further reacts in air to form basic magnesium carbonate with a lower yield. It may also form mixed basic salts, which further react in air to form basic magnesium carbonate with a relatively lower yield.

[0034] In this embodiment, by optimizing the electrolytic cell design, electrode materials, and operating parameters, efficient coupling and synergistic enhancement of CO2 mineralization, hydrogen production, and high-purity product generation are achieved. OH- generated in situ at the cathode is utilized. - As the sole alkali source required for mineralization, it completely eliminates the need for external alkali additives (such as lime or caustic soda), reducing costs and process complexity from the outset. Furthermore, it integrates traditionally separate processes (alkali production + mineralization + hydrogen production), minimizing intermediate steps and energy losses. The controllable design of the anode reaction (chlorine production, oxygen production, or sacrificial dissolution) allows for optimization of overall economics based on product market and electricity prices, improving the material and energy utilization efficiency of the entire system.

[0035] like Figure 2 As shown, another aspect of this disclosure proposes an electrochemically assisted system 200 for simultaneous hydrogen production and basic magnesium carbonate production from CO2 mineralization in seawater. This system includes a cathode chamber 210 and an anode chamber 220, and a selective ion exchange membrane 230 separating the cathode chamber 210 and the anode chamber 220. The cathode chamber 210 is further provided with an inlet for introducing concentrated seawater, a solid outlet for separating magnesium-based compounds, and a hydrogen outlet for exporting hydrogen. The anode chamber 220 is provided with a chlorine outlet for exporting chlorine products.

[0036] In some preferred embodiments, the selective ion exchange membrane can preferably be an AEM anion exchange membrane, which effectively isolates the anode and cathode chambers, preventing cross-contamination of products (such as Cl2 entering the cathode chamber to oxidize H2, or Mg(OH)2 precipitating into the anode chamber), while allowing specific ions (such as Cl2) to enter the cathode chamber. - OH - They migrate to maintain charge balance.

[0037] In other preferred embodiments, the cathode material in the cathode chamber can preferably be a material with high specific surface area and high hydrogen evolution activity, such as a platinum-plated titanium mesh, nickel foam, or carbon-based material. These materials can create a high-pH localized region on the electrode surface, greatly promoting the dissolution and hydration of CO2, as well as the subsequent carbonate generation and precipitation reactions.

[0038] It should be noted that the high-purity hydrogen produced in this embodiment can be used as an energy carrier, and the separated magnesium-based compound may be magnesium hydroxide or basic magnesium carbonate. Magnesium hydroxide further generates basic magnesium carbonate in the air, and the final basic magnesium carbonate product is used in flame retardants, papermaking, magnesium salt precursors, etc.

[0039] This disclosure develops a dedicated membrane electrolyzer system suitable for this coupled reaction. Through electrode material selection (high hydrogen evolution activity cathode, corrosion-resistant / selective oxidation anode), ion exchange membrane optimization, and reactor hydrodynamic design, it achieves effective isolation of the reaction zone, enhanced mass transfer process, and in-situ product separation, resolving the efficiency-purity contradiction in the coupled process. High-purity hydrogen, high-value-added magnesium-based chemicals, and potential anode chemicals (chlorine / oxygen) are produced simultaneously. The entire process achieves "carbon-negative" hydrogen production, simultaneously sequestering a significant amount of CO2 per unit of hydrogen produced, resulting in outstanding environmental benefits.

[0040] The following will further illustrate the method of electrochemically assisted simultaneous hydrogen production and basic magnesium carbonate production from seawater mineralization of CO2: Example 1 S1: Electrolyte preparation and feeding The system uses evaporated and concentrated seawater as the cathode electrolyte, which can pre-treat the raw material solution to remove large suspended particles or some impurities.

[0041] S2: Electrochemical-assisted CO2 mineralization and simultaneous hydrogen production The cathode electrolyte is pumped into the cathode chamber of the membrane electrolyzer. Simultaneously, air (CO2 concentration of 0.04 vol.%) is introduced into the cathode chamber.

[0042] Cathode reaction: The preferred cathode is a platinum-plated titanium mesh, with a current density of 100 mA / cm². 2 At a temperature of 25℃, the following reaction occurs: 2H₂O + 2e⁻ - → H2↑ + 2OH - The generated OH - Immediately increase the local pH of the catholyte.

[0043] CO2 absorption and mineralization: CO2 rapidly hydrates in an alkaline microenvironment and reacts with OH-. - The reaction produces CO3 2- This leads to the reaction with Mg in the solution. 2+ They combine to form Mg(OH)2 or basic magnesium carbonate precipitate. This precipitate grows and precipitates under electrolyte circulation or external stirring / fluidization conditions.

[0044] Anode reaction: In the anode chamber, the following chlorine evolution reaction will occur first: 2Cl - → Cl2↑ + 2e -This produces chlorine as a byproduct.

[0045] S3: Online separation and purification of products Hydrogen separation: The hydrogen produced at the cathode is separated from the electrolyte in a gas-liquid separator. After condensation, drying, and possible deoxygenation purification, hydrogen products are obtained.

[0046] Solid product separation: The cathode effluent rich in solid precipitates enters the hydrocyclone. The separated wet solids are washed (to remove adsorbed salts) and dried to obtain magnesium hydroxide or basic magnesium carbonate products.

[0047] S4: Anode Product Management and System Integration The anode products are safely collected and processed. Chlorine gas can be cooled and dried before being used as a chemical raw material.

[0048] The simulation results for Example 1 are shown in Table 1. The cell voltage was 2.4V, and the H2 yield was 3.7 mol / (h·m³). 2 The main solid product is Mg(OH)₂, which further reacts with air to form basic magnesium carbonate, with a yield of 0.05 kg / (h·m³). 2 The yield is extremely low, with an energy consumption of 52 kWh / kg H2 per unit of H2.

[0049] Example 2 The method in Example 2 is the same as that in Example 1, except that the temperature is 40°C, the CO2-containing gas is flue gas, and the CO2 concentration in the flue gas is 15 vol.%.

[0050] The simulation results for Example 2 are shown in Table 1. The cell voltage was 2.3V, and the H2 yield was 3.73 mol / (h·m³). 2 The solid product is mainly a mixed basic salt, which further yields basic magnesium carbonate in a yield of 0.30 kg / (h·m). 2 The energy consumption per unit of H2 is 50 kWh / kg H2.

[0051] Example 3 The method in Example 3 is the same as that in Example 1, except that the temperature is 55°C and the CO2-containing gas is pure CO2, that is, the concentration of CO2 is 100 vol..

[0052] The simulation results for Example 3 are shown in Table 1. The cell voltage was 2.2V, and the H2 yield was 3.73 mol / (h·m³). 2 The solid product is mainly basic magnesium carbonate, with a yield of 0.35 kg / (h·m³). 2 The energy consumption per unit of H2 is 48 kWh / kg H2.

[0053] Example 4 The method in Example 4 is the same as in Example 1, except that the current density is 300 mA / cm². 2 The temperature is 40℃. The simulation results for Example 4 are shown in Table 1. The cell voltage was 3.1V, and the H2 yield was 11.2mol / (h·m). 2 The main solid product is Mg(OH)₂, which further reacts with air to form basic magnesium carbonate, with a yield of 0.15 kg / (h·m³). 2 The energy consumption per unit of H2 is 73 kWh / kg H2.

[0054] Example 5 The method in Example 5 is the same as that in Example 1, except that the current density is 300 mA / cm². 2 The temperature is 55℃, and the gas containing CO2 is flue gas with a CO2 concentration of 15 vol.%. The simulation results for Example 5 are shown in Table 1. The cell voltage was 3.0V, and the H2 yield was 11.2 mol / (h·m). 2 The solid product is mainly a mixed basic salt, which further yields basic magnesium carbonate at a yield of 0.95 kg / (h·m³). 2 The energy consumption per unit of H2 is 71 kWh / kg H2.

[0055] Example 6 The method in Example 6 is the same as in Example 1, except that the current density is 300 mA / cm². 2 The gas containing CO2 is flue gas, and the concentration of CO2 in the flue gas is 15 vol.%. The simulation results for Example 6 are shown in Table 1. The cell voltage was 3.0V, and the H2 yield was 11.2 mol / (h·m). 2 The solid product is mainly basic magnesium carbonate, with a yield of 1.05 kg / (h·m³). 2 The energy consumption per unit of H2 is 75 kWh / kg H2.

[0056] Example 7 The method in Example 7 is the same as in Example 1, except that the current density is 500 mA / cm². 2 The temperature is 55℃. The simulation results for Example 7 are shown in Table 1. The cell voltage was 3.9V, and the H2 yield was 18.7 mol / (h·m). 2 The main solid product is Mg(OH)₂, which further reacts with air to form basic magnesium carbonate, with a yield of 0.25 kg / (h·m³). 2The energy consumption per unit of H2 is 88 kWh / kg H2.

[0057] Example 8 The method in Example 8 is the same as in Example 1, except that the current density is 500 mA / cm². 2 The gas containing CO2 is flue gas, and the concentration of CO2 in the flue gas is 15 vol.%. The simulation results for Example 8 are shown in Table 1. The cell voltage was 4.0V, and the H2 yield was 18.7 mol / (h·m). 2 The solid product is mainly a mixed basic salt, which further yields basic magnesium carbonate at a yield of 1.40 kg / (h·m³). 2 The energy consumption per unit of H2 is 90 kWh / kg H2.

[0058] Example 9 The method in Example 9 is the same as in Example 1, except that the current density is 500 mA / cm². 2 The gas containing CO2 is pure CO2, that is, the concentration of CO2 is 100 vol.%, and the temperature is 40℃. The simulation results for Example 9 are shown in Table 1. The cell voltage was 3.8V, and the H2 yield was 18.7 mol / (h·m). 2 The solid product is mainly basic magnesium carbonate, with a yield of 1.55 kg / (h·m³). 2 The energy consumption per unit of H2 is 85 kWh / kg H2.

[0059] Table 1. Parameters and index results for each embodiment

[0060] In summary, based on the results in Table 1, it can be seen that the H2 yield is strongly positively correlated with the current density at 100, 300, and 500 mA / cm². 2 Under these conditions, the yields stabilized at approximately 3.7, 11.2, and 18.7 mol / (h·m⁻²), respectively. 2 The solid yield and product type are jointly determined by the current density and CO2 concentration. The higher the current density, the higher the solid yield, but also the higher the cell voltage and energy consumption per unit of H2. Secondly, low concentration (air) mainly produces Mg(OH)2 with extremely low yield; medium concentration (flue gas) produces mixed basic salts with significantly improved yield; high concentration (pure CO2) produces basic magnesium carbonate with the highest yield.

[0061] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for electrochemically assisted seawater mineralization of CO2 to simultaneously produce hydrogen and basic magnesium carbonate, characterized in that, The method includes: The anode chamber and cathode chamber are separated by a selective ion exchange membrane. Concentrated seawater is added to the cathode chamber, and CO2-containing gas is introduced into the cathode chamber or a mineralization reaction zone connected to the cathode chamber. The cathode is made of a material with high specific surface area and high hydrogen evolution activity, and OH- is generated through water electrolysis. - and hydrogen, OH - With CO2 and Mg 2+ The reaction forms a solid precipitate of magnesium-based compounds; In the anode chamber, a chlorine evolution reaction occurs, producing chlorine gas as a byproduct; The hydrogen produced at the cathode is separated from the electrolyte in a gas-liquid separator. The hydrogen is then condensed, dried, and purified to obtain the hydrogen product. The cathode effluent rich in solid precipitates enters the solid-liquid separation unit for separation. The separated wet solids are washed and dried to obtain basic magnesium carbonate product.

2. The method according to claim 1, characterized in that, The cathode is made of platinum-plated titanium mesh, nickel foam, or carbon-based material.

3. The method according to claim 1, characterized in that, The selective ion exchange membrane is an AEM anion exchange membrane.

4. The method according to claim 1, characterized in that, The current density in the cathode chamber is 300-500 mA / cm². 2 .

5. The method according to claim 1, characterized in that, The temperature of the cathode chamber is 40-55°C.

6. The method according to claim 1, characterized in that, The CO2-containing gas is power plant flue gas, lime kiln gas, air, or pure CO2.

7. The method according to claim 1, characterized in that, When the CO2-containing gas is power plant flue gas, lime kiln gas, or air, the CO2 concentration is 0.04-15 vol.%.

8. A system for electrochemically assisted seawater mineralization of CO2 to simultaneously produce hydrogen and magnesium carbonate, characterized in that, The system includes a cathode chamber and an anode chamber, and a selective ion exchange membrane separating the cathode chamber and the anode chamber; wherein, The cathode chamber is also provided with an inlet for introducing concentrated seawater, a solid outlet for separating magnesium-based compounds, and a hydrogen outlet for discharging hydrogen. The anode chamber is equipped with a chlorine outlet for discharging chlorine products.

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