A three-chamber CO2 mineralization membrane electrolysis system and method for producing high-purity carbonates from solid waste.

Abstract

This invention discloses a three-chamber CO2 mineralization membrane electrolysis system and method for producing high-purity carbonates from solid waste, belonging to the field of electrochemical technology. It includes an electrolysis reactor and a power supply. The electrolysis reactor comprises an anode chamber, an intermediate chamber, and a cathode chamber. Powered by the power supply, the system utilizes an electrochemical PCET reaction to alter the pH environment of the solutions at both the anode and cathode, promoting CO2 absorption in the cathode region and acid production in the anode region. Acid production in the intermediate chamber is achieved through the selective permeation of H+ ions via a cation exchange membrane. The high-concentration acid is then used to recover and utilize natural minerals or alkaline solid waste, realizing both solid waste treatment and high-purity carbonate production. H2 generated at the cathode regenerates the anolyte outside the system, thus achieving continuous and stable operation of the CO2 mineralization membrane electrolysis. This invention improves the stability and current efficiency of the electrolysis system, reduces energy consumption, enables the production of high-concentration acid, and simplifies the system's process flow.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically, to a three-chamber CO2 mineralization membrane electrolysis system and method for producing high-purity carbonates from solid waste. Background Technology

[0002] CO2 mineralization refers to the process of converting CO2 into inorganic carbonates, and it is one of the key technologies for CO2 emission reduction and utilization (CCU). Currently, many studies have been carried out both domestically and internationally on CO2 mineralization using bulk calcium and magnesium salt ores (serpentine, olivine, wollastonite) or solid wastes (carbide slag, steel slag, red mud).

[0003] However, current CO2 mineralization technologies generally face technical challenges such as high energy consumption and cost for mineralization reaction activation, low economic value of products, and environmental pollution from wastewater generation, limiting the feasibility of large-scale application of CO2 mineralization technologies. Combining cutting-edge electrochemical CO2 emission reduction technologies with natural minerals or solid waste treatment using a proton cycle-driven technology route can effectively reduce mineralization energy consumption while improving resource recovery rates, potentially achieving a large-scale, economical, and low-energy integrated CO2 mineralization process encompassing "CO2 emission reduction - solid waste treatment - resource recovery - chemical production." Current CO2 mineralization membrane electrolysis technologies typically use organic proton-coupled electron transfer (PCET) reactants or recycled H2 as the carrier for electrochemical redox reactions. A major challenge with recycled H2 is that the electrochemical oxidation reaction requires a gas diffusion electrode, and the difficult-to-control three-phase reaction interface easily leads to electrode "flooding," causing electrode failure and unstable reaction operation. A core challenge with organic PCET reactants is the impact of O2 on system stability. Especially on the cathode side where CO2 is absorbed, the presence of even a small amount of O2 (gaseous oxygen or dissolved oxygen) can cause a rapid decay of electrochemical PCET reactants, making it difficult for the system to operate stably. In particular, CO2 mineralization membrane electrolysis systems often require the direct treatment of natural minerals or alkaline solid waste with acidic anolytes. If PCET reactants are used as electrochemical redox carriers, it will cause irreversible loss of organic PCET reactants. Adding an additional separation process between acid and PCET reactants will undoubtedly increase the operating cost of the device. At the same time, PCET reactants will also affect the purity of the products recovered from natural minerals or alkaline solid waste, further reducing the economic feasibility of the membrane electrolysis system.

[0004] Therefore, simplifying the process flow of CO2 mineralization membrane electrolysis system to enable it to operate continuously and stably at low cost is a technical challenge that urgently needs to be overcome. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a three-chamber CO2 mineralization membrane electrolysis system and method for producing high-purity carbonates from solid waste. This system improves the stability and current efficiency of electrolysis, reduces energy consumption, and enables the production of high-concentration acids. It can be directly connected to the subsequent calcite dissolution process, avoids the separation process between acid and PCET reactants, simplifies the system's process flow, and reduces the impact of PCET reactants on product purity.

[0006] The objective of this invention is achieved through the following solution: A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste includes an electrolysis reactor and a power supply. The electrolysis reactor comprises an anode chamber, an intermediate chamber, and a cathode chamber. Powered by the power supply, the system utilizes an electrochemical PCET reaction to alter the pH environment of the solutions at both the anode and cathode, promoting CO2 absorption in the cathode region and acid generation in the anode region. H+ is then selectively permeated through a cation exchange membrane. + The system enables the production of acid in the intermediate chamber and utilizes high-concentration acid to recycle natural minerals or alkaline solid waste, thereby achieving solid waste treatment and the production of high-purity carbonates. The H2 generated at the cathode is used to reduce and regenerate the anolyte outside the system, thus achieving continuous and stable operation of CO2 mineralization membrane electrolysis.

[0007] Furthermore, the process of recycling natural minerals or alkaline solid waste using high-concentration acids specifically involves dissolving calcite in an intermediate chamber solution and mineralizing CO2 in a cathode solution after electrolysis, thereby achieving solid waste treatment and the production of high-purity carbonates.

[0008] Furthermore, an acid containing reduced PCET reactant QH2 is added to the anode chamber of the electrolytic reactor, a strong base-weak acid salt solution is added as a buffer to the intermediate chamber, and a saturated sodium bicarbonate solution is added to the cathode chamber. During electrolysis, a hydrogen evolution reaction occurs at the cathode, and hydrogen gas is circulated to the reduction tower in the anode area to combine with PCET reactant Q, and is oxidized at the anode to form H. + H + The solution passes through the first cation exchange membrane and enters the intermediate chamber to form an acetate-sodium acetate buffer system. The Na+ released from the ionization of the solution in the intermediate chamber... + It enters the cathode chamber through the second cation exchange membrane to maintain the charge balance of the system; After electrolysis, the solution in the intermediate chamber reacts with calcite to form calcium acetate, and then reacts with sodium sulfate to form gypsum. The filtered liquid phase is used again as the initial solution in the intermediate chamber. The cathode reacts with carbon dioxide to obtain sodium bicarbonate as a mineralization product, and the filtered liquid phase is used again as the initial electrolyte in the cathode chamber.

[0009] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, wherein the H2 carrier for the redox reaction in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described in any of the preceding claims can be replaced with organic PCET reactants.

[0010] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste is provided. The assembly method of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described above is adaptable to different environments. Under the premise that the buffer system meets the production conditions, a weak acid system can be directly used as the anolyte, and the electrolysis cell can be modified into a two-chamber system through an extraction process.

[0011] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, wherein the anolyte acid in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described above is not limited to sulfuric acid, but also includes any one of hydrochloric acid and phosphoric acid.

[0012] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, wherein the electrochemical PCET reactants used in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described in any of the preceding claims include quinones, tungstic acid, pyridines, phenazines and their derivatives.

[0013] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, wherein the electrolyte added to the cathode chamber of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described in any of the preceding claims is saturated sodium bicarbonate, but can also be replaced with other salts or alkaline solutions.

[0014] A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, wherein the CO2 mineralization process in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste as described in any of the preceding claims includes the use of pure CO2 gas or impure CO2 gas.

[0015] A three-chamber CO2 mineralization membrane electrolysis method for producing high-purity carbonates from solid waste includes: Step 1: Construct a three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, as described in any of the above items; Step 2: Based on this system, complete the CO2 mineralization membrane electrolysis for producing high-purity carbonates from solid waste.

[0016] The beneficial effects of this invention include: This invention's system creates conditions for subsequent calcite dissolution, gypsum production, and CO2 mineralization through membrane electrolysis. While achieving CO2 mineralization, it has the potential to treat solid waste and simultaneously produce high-purity carbonate products. Furthermore, the reduction unit in the anode region prevents the formation of unstable three-phase interfaces inherent in the original hydrogen circulation system, avoiding the use of gas diffusion electrodes. Simultaneously, utilizing an asymmetric battery structure, hydrogen evolution occurs at the cathode, preventing losses caused by PCET reactants contacting oxygen and improving the system's electrolytic stability. In addition, the system introduces an intermediate chamber as a buffer, which not only mitigates proton entry into the cathode chamber, improving electrolysis current efficiency and reducing system energy consumption, but also enables the production of high-concentration acids. This allows for direct connection to the subsequent calcite dissolution process, avoiding the separation process between acid and PCET reactants, simplifying the system's process flow, and reducing the impact of PCET reactants on product purity. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates in an embodiment of the present invention; Figure 3 This is a cyclic voltammetry curve of the PCET reactants in an embodiment of the present invention; Figure 4 This is a voltage-time curve of mineralized calcite in an embodiment of the present invention; Figure 5 This is an XRD characterization diagram of the mineral recycling products in an embodiment of the present invention; Figure 6 This is an XRD characterization diagram of the CO2 mineralization product in an embodiment of the present invention; Figure 7 This is a TGA characterization diagram of CO2 mineralization products in an embodiment of the present invention; Figure 8 This is a voltage-time curve of mineralized calcite in an embodiment of the present invention; Figure 9 This is a voltage-time curve of mineralized calcite in the comparative example of this invention; Figure 10This is a voltage-time curve of mineralized calcite in the comparative example of this invention; Among them, 1-external power supply; 2-electrolysis reactor; 3-anode chamber; 4-cation exchange membrane; 5-intermediate chamber; 6-cation exchange membrane; 7-cathode chamber; 8-gas-liquid separator; 9-hydrogen dryer; 10-carbon dioxide absorption tower; 11-bicarbonate crystallizer; 12-reduction and regeneration tower; 13-hydrogen storage tank; 14-acid dissolution reactor; 15-precipitation reactor. Detailed Implementation

[0019] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0020] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] In its inventive concept, this invention simplifies the process flow of a CO2 mineralization membrane electrolysis system, avoiding the separation step between acid and PCET reactants. In practical applications, the system can be powered by an external power source, utilizing the electrochemical PCET reaction to alter the pH environment of the solutions at both the cathode and anode, promoting CO2 absorption at the cathode and acid generation at the anode, and selectively allowing H2 to permeate through the cation exchange membrane. + This system enables the production of acid in the intermediate chamber and utilizes high-concentration acid for the high-resource conversion and recovery of natural minerals or alkaline solid waste. H2 generated at the cathode regenerates the anolyte outside the system, thus achieving a short-process, low-cost, and high-resource-conversion-rate continuous and stable CO2 mineralization membrane electrolysis operation. Specifically, the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates utilizes an external power supply to alter the pH environment of the anode and cathode solutions. After electrolysis, the intermediate chamber solution dissolves calcite, and the cathode solution mineralizes CO2, thereby achieving both solid waste treatment and high-purity carbonate production.

[0022] First, an acid (such as sulfuric acid or phosphoric acid) containing the reduced PCET reactant QH2 is added to the anode chamber of the system. A strong base-weak acid salt solution (such as sodium acetate) is added as a buffer in the intermediate chamber, and a saturated sodium bicarbonate solution is added to the cathode chamber. During electrolysis, a hydrogen evolution reaction occurs at the cathode, and hydrogen gas is circulated to the reduction tower in the anode region to combine with the PCET reactant Q, and is oxidized at the anode to form H2. + H + The solution passes through the first cation exchange membrane and enters the intermediate chamber to form an acetate-sodium acetate buffer system. The Na+ released from the ionization of the solution in the intermediate chamber... + The electrolyte enters the cathode chamber through a second cation exchange membrane to maintain the system's charge balance. After electrolysis, the intermediate chamber solution reacts with calcite (mainly calcium carbonate) to form calcium acetate, which then reacts with sodium sulfate (mainly sodium sulfate) to form gypsum (mainly calcium sulfate dihydrate). The filtered liquid phase can be used again as the initial solution for the intermediate chamber. The cathode reacts with carbon dioxide to obtain sodium bicarbonate as a mineralization product, and the filtered liquid phase can be used again as the initial electrolyte for the cathode chamber. The entire membrane electrolysis mineralization process operates in this cyclical manner.

[0023] Specifically, the principle of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates is as follows: Figure 1 As shown, it includes an external power supply 1 and an electrolysis reactor 2.

[0024] The electrolytic reactor is an electrolytic cell structure, including a cathode region 7, an anode region 3, an intermediate chamber 5, a cation exchange membrane 4 separating the anode region from the intermediate chamber, and a cation exchange membrane 6 separating the intermediate chamber from the cathode region.

[0025] The cathode is a hydrogen evolution electrode, where an electrochemical reduction reaction occurs, water is decomposed to produce H2, and the alkalinity of the cathode solution continuously increases. The reaction equation is as follows: Cathode reaction: 2H₂O + 2e⁻ - →H2+2OH - Cathode reaction: 2OH - +2HCO3 - →2CO3 2- +2H2O Cathode region 7 is connected to gas-liquid separator 8. A hydrogen dryer 9 is installed at the outlet of gas-liquid separator 8. H2 first enters H2 storage tank 13, then enters the reduction and regeneration tower on the anode side, where it combines with the oxidized PCET reactant Q to form QH2. The anode is a graphite felt electrode, where an electrochemical oxidation reaction of the organic PCET reactant occurs, oxidizing the reduced QH2 into Q and H. + The reaction equation is as follows: Reduction tower reaction: Q + H2 → QH2 Anode reaction: QH2→Q+2H ++2e - H generated at the anode + The solution enters the intermediate chamber 5 through the cation exchange membrane 4, and then proceeds to the calcite dissolution process in the acid dissolution reactor 14. The mother liquor filtered in the precipitation reactor 15 reacts with sodium sulfate to obtain the gypsum product, simultaneously regenerating the solution in the intermediate chamber. The solution is then recycled back to the intermediate chamber 5. The reaction is as follows: Calcite dissolution: 2HAc + CaCO3 → Ca(Ac)2 + H2O + CO2↑ Gypsum production: Ca(Ac)2 + Na2SO4 → 2NaAc + CaSO4↓ After passing through the gas-liquid separator 8, the catholyte enters the CO2 absorption tower 10, where it crystallizes to form sodium bicarbonate in the bicarbonate crystallizer 11. The mother liquor is then recycled back to the cathode zone 7. The reaction is as follows: CO2 mineralization: Na2CO3 + CO2 + H2O → 2NaHCO3↓ This system enables the direct treatment of solid waste, the production of high-purity carbonate products, and the mineralization of CO2 through a hydrogen circulation membrane electrolysis process based on the PCET reaction.

[0026] The technical solution of this invention has the following technical effects: (1) The system of the present invention includes four main processes: external power supply electrolysis, electrochemical PCET reaction, high-concentration acid treatment of natural minerals or alkaline solid waste, and non-electrochemical reaction reduction and regeneration; wherein, the external power supply provides energy for the electrochemical reaction, the anode undergoes an oxidation reaction of organic PCET reactants, and H+ is released. + Increase the acidity of the anolyte, and allow H+ to pass through the cation exchange membrane. + The solution is transferred to the intermediate chamber, where a high-concentration acid is produced and directly used to treat natural minerals or alkaline solid waste. An electrochemical hydrogen evolution reaction occurs at the cathode, increasing the alkalinity of the cathode solution, which is then used to absorb CO2 generated during the treatment of natural minerals or alkaline solid waste in the intermediate chamber, producing HCO3. - Ions, metal cations in the intermediate chamber (such as Na) + K + (etc.) reach the cathode side through the cation exchange membrane and react with HCO3 on the cathode side. - High-purity bicarbonate is generated. Finally, the hydrogen produced at the cathode is used by the catalyst to reduce the organic PCET reactants at the anode, thereby regenerating the anolyte.

[0027] (2) The system of the present invention includes an external power supply and an electrolytic reactor. The electrolytic reactor is an electrolytic cell structure, including an anode and cathode chamber, an intermediate chamber, and a cation exchange membrane separating the chambers. The anode is filled with a mass-electric coupling agent and H2SO4 solution, the intermediate chamber is filled with NaAc solution, and the cathode is filled with NaHCO3 solution. The cathode is a hydrogen evolution electrode (e.g., a platinum electrode, a platinum-nickel plated mesh, etc.).

[0028] (3) The system of the present invention is equipped with a gas-liquid separator, a CO2 absorption tower and a bicarbonate crystallizer on the cathode side; under the action of current, an electrochemical reduction reaction occurs at the cathode to decompose water and produce H2 and OH. - This increases the alkalinity of the catholyte, and the reaction equation occurring on the cathode side is: 2H₂O + 2e⁻ - →2OH - +H2. The alkaline-rich catholy solution is fed into a gas-liquid separator to separate H2 and the catholy solution. The catholy solution is then fed into a CO2 absorption tower to mineralize CO2 and produce NaHCO3. The NaHCO3-rich solution is fed into a bicarbonate crystallizer to produce high-purity carbonate products. The mother liquor is recycled to the cathode side of the electrolytic cell. The reaction equation for CO2 mineralization in the CO2 absorption tower is: CO2 + NaOH → NaHCO3.

[0029] (4) The anode of the system of the present invention is a graphite felt electrode, which undergoes an electrochemical oxidation reaction of organic PCET reactant QH2 (such as quinone derivatives) and releases H. + This increases the acidity of the anolyte. The reaction equation on the anolyte side is: QH2→Q+2H + +2e - (Q / QH2 are the oxidized and reduced states of the organic PCET reactants, respectively).

[0030] (5) The system of the present invention is provided with an acid dissolution reactor and a precipitation reactor on the intermediate chamber side, and H generated by electrochemical reaction on the anode side. + A high-concentration acid solution is formed in the intermediate chamber of the cation exchange membrane. The high-concentration acid solution is passed into the acid dissolution reactor and reacts directly with natural minerals or alkaline solid waste to generate CO2 and calcium salt solution. The CO2 is recycled to the CO2 absorption tower on the cathode side. The calcium salt solution is passed into the precipitation reactor and reacts with sodium sulfate (Na2SO4) to generate CaSO4 precipitate and sodium salt electrolyte. The sodium salt electrolyte enters the intermediate chamber for recycling.

[0031] (6) The system of the present invention has a reduction and regeneration tower on the anode side. The substance Q, which is rich in the oxidized state of organic PCET, enters the reduction and regeneration tower and undergoes non-electrochemical reduction with H2 separated from the gas-liquid separator on the cathode side in the environment of platinum-carbon catalyst to generate QH2. The non-electrochemical reduction and regeneration reaction equation of QH2 is: Q + H2 → QH2.

[0032] (7) In the system of the present invention, the anolyte rich in QH2 is circulated into the anode chamber of the electrolytic cell at the outlet of the reduction and regeneration tower to achieve stable circulation of the organic PCET reactants. The anode of this system uses water-soluble organic PCET reactants, which release H2 through electrochemical oxidation. + The acidity of the intermediate chamber solution is selectively increased by permeating through the cation exchange membrane. Cations in the intermediate chamber electrolyte reach the cathode side through the membrane, providing a cation source for cathode CO2 mineralization. Electrochemical PCET reactants include, but are not limited to, quinones, tungstic acid, pyroxenes, phenazines and their derivatives (AQDS, silicotungstic acid, phosphotungstic acid, FMN, DHPS, DHPC, BHPC, etc.), with the structures shown below, where R... n =-H, -OH, -COOH, -SO3H, -NH2, -CH3, -O-, -S-, -CH2-, -F, or -Cl. It can also be replaced with inorganic PCET reactants or polymers with PCET reaction properties, such as MnOOH, NiOOH, polyaniline, etc.

[0033]

[0034] (8) In the system of the present invention, the reduction and regeneration of organic PCET reactants are carried out outside the electrolysis system. Under the action of a catalyst, the oxidized state of the organic PCET reactants undergoes a spontaneous redox reaction with H2, thereby realizing the reduction and regeneration cycle of the organic PCET reactants. Available reduction and regeneration catalysts include: Pt, Pt / C, Pd / C, Ni, etc.

[0035] Furthermore, the advantages of the technical solution of the present invention are as follows: 1. The system of this invention uses organic PCET reactants at the anode. Because the anode side only involves a solid-liquid two-phase electrochemical reaction, the use of a gas diffusion electrode is avoided, completely eliminating the electrochemical "gas-liquid-solid" three-phase reaction interface and significantly improving the system's long-term operational stability. At the cathode side, a hydrogen evolution reaction occurs while CO2 is absorbed, completely avoiding the influence of O2 and dissolved oxygen in CO2 on the organic PCET reactants at the cathode. Simultaneously, the H2 generated at the cathode can act as a reducing agent to regenerate the organic PCET reactants, thereby achieving continuous and stable operation of the CO2 mineralization membrane electrolysis system.

[0036] 2. The system of this invention enables low-cost, high-resource-conversion-rate, continuous, and stable operation of a CO2 mineralization membrane electrolysis system. In practical applications, this system can be powered by an external power source and utilizes the electrochemical PCET reaction to alter the pH environment at both the anode and cathode, promoting CO2 absorption at the cathode and acid generation at the anode. H2 is then selectively permeated through the cation exchange membrane. +This system enables the production of acid in the intermediate chamber and utilizes high-concentration acid to directly recycle natural minerals or alkaline solid waste with a high resource conversion rate. H2 generated at the cathode is used externally to reduce and regenerate the anolyte, thus achieving a low-cost, high-resource-conversion, continuous, and stable CO2 mineralization membrane electrolysis process.

[0037] 3. The system of this invention uses a cation exchange membrane and an intermediate buffer chamber to separate the anode and cathode liquids, completely avoiding interference from O2 on the anode organic PCET reactants on the cathode CO2 absorption side, and enabling direct mineralization of CO2 (oxygen-containing CO2) under real-world conditions. Simultaneously, the H in the anode region... + The metal cations in the intermediate chamber reach the cathode region through the cation exchange membrane, achieving charge balance in the system and forming a bicarbonate solution with the CO2 mineralized at the positive electrode. This solution can be crystallized to saturation to produce high-purity, high-value-added bicarbonate products.

[0038] 4. The system of this invention selectively permeates H through a cation exchange membrane. + The intermediate chamber enables the production of high-concentration acid, avoiding the separation process between acid and PCET reactants. This high-concentration acid can be directly used to recycle natural minerals or alkaline solid waste with a high resource conversion rate. At the same time, it can also regenerate the sodium salt electrolyte in the intermediate chamber.

[0039] 5. Based on thermodynamic analysis, the redox potential of organic PCET reactants in this invention must be higher than the hydrogen potential in an acidic environment to ensure the spontaneous reduction of organic PCET reactants by H2 under the action of a catalyst outside the electrochemical system. Simultaneously, the potential difference between the organic PCET reactants and the hydrogen evolution reaction reflects the theoretical minimum input energy. To ensure that the anolyte can be spontaneously reduced by hydrogen under the action of a catalyst, while avoiding high electrolysis energy consumption, this system uses quinone derivatives (e.g., AQDS), fluoroquinone / isofluoroquinone derivatives (e.g., FMN), or phenazine derivatives (e.g., DHPS, DHPC, BHPC) with suitable potentials as organic PCET reactants, enabling spontaneous reduction of the anolyte and a low-energy CO2 mineralization membrane electrolysis process.

[0040] 6. The redox reaction carrier in the system of this invention is H2, but it can be replaced with other mass-to-electrode coupling agents, such as organic PCET reactants including but not limited to phenazine, pyrazine, quinone and their derivatives. The organic PCET reactant at the battery negative electrode undergoes an electrochemical oxidation reaction, releasing H2. + The acidification solution reduces the alkalinity of the negative electrode solution; the organic PCET reactants at the positive electrode undergo an electrochemical reduction reaction, accepting H+. + Alkalinization of the solution increases the alkalinity of the positive electrode solution.

[0041] 7. The catalyst in the anolyte reduction and regeneration tower of the present invention is an acid-resistant platinum-supported catalyst. This type of catalyst is widely used in industrial H2 reduction reactions, is simple to prepare, and has low cost. The cation exchange membrane of the system uses Nafion 115, Nafion 117, and domestic membranes, which have low cost.

[0042] 8. The entire system of this invention can be designed as a simple integrated device according to requirements, or it can be designed into a large-scale integrated device through series and parallel connections. It can be applied to CO2 capture in environments including flue gas from coal-fired power plants, factory exhaust gas, transportation exhaust gas, and even the atmosphere. The mineral raw materials used include, but are not limited to, natural minerals such as wollastonite, serpentine, olivine, and potassium feldspar; or industrial alkaline solid wastes such as carbide slag, biomass ash, fly ash, steel slag, and red mud. The system can operate continuously without interruption, without time or space limitations.

[0043] Example 1 This embodiment provides a three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, including an external power supply 1 and an electrolysis reactor 2.

[0044] Electrolytic reactor 2 is an electrolytic cell structure, including a cathode chamber 7, an anode chamber 3, an intermediate chamber 5, and a cation exchange membrane 4 separating the anode region from the intermediate chamber, and a cation exchange membrane 6 separating the intermediate chamber 5 from the cathode chamber 7. The cathode is a hydrogen evolution electrode, where an electrochemical reduction reaction occurs, and the anode is a graphite felt electrode, where an electrochemical oxidation reaction occurs on organic PCET (in this embodiment, PCET stands for Proton-cycled electron transfer, commonly referred to as proton-coupled electron transfer or mass-electric coupling) reactants.

[0045] A gas-liquid separator 8, a carbon dioxide absorption tower 10, and a bicarbonate crystallizer 11 are provided on the cathode side. The cathode chamber 7 is connected to the gas-liquid separator 8, the gas-liquid separator 8 is connected to the carbon dioxide absorption tower 10, the carbon dioxide absorption tower 10 is connected to the bicarbonate crystallizer 11, and the bicarbonate crystallizer 11 is connected to the cathode chamber 7. Preferably, a hydrogen dryer 9 is provided at the outlet of the gas-liquid separator.

[0046] An acid dissolution reactor 14 and a precipitation reactor 15 are installed in the intermediate chamber 5. The intermediate chamber 5 is connected to the acid dissolution reactor 14, the acid dissolution reactor 14 is connected to the precipitation reactor 15, and the precipitation reactor 15 is connected to the intermediate chamber 5. The acid dissolution reactor 14 is also connected to the CO2 absorption tower 10 on the cathode side.

[0047] A reduction and regeneration tower 12 is provided on the anode side; the reduction and regeneration tower 12 is circulatedly connected to the anode chamber 3, and the reduction and regeneration tower 12 is also connected to the hydrogen dryer 9 on the cathode side through a hydrogen storage tank 13.

[0048] The system structure of this embodiment is as follows: Figure 2 As shown in the diagram, the connection relationship between the various devices in the system is illustrated above, and the process is as follows: Figure 1 As shown, the raw materials used are as follows: analytical grade concentrated sulfuric acid, sodium sulfate, sodium bicarbonate, sodium acetate, and quinone derivatives were directly used as experimental materials. Calcite was obtained from Lingshou County Jiubao Building Materials Sales Department. H2 and Ar with a purity of 99.99% and CO2 were purchased from Heping (Sichuan) Gas Company. The Pt / C catalyst was purchased from Hesen (Shanghai) Company. The cation exchange membrane used was a Nafion 115 membrane (DuPont). A nickel-plated platinum mesh (which can be made in the laboratory) was used as the cathode electrode.

[0049] In this embodiment, anthraquinone 2,7-disulfonic acid disodium salt (2,7-AQDS) was used as the PCET reactant, and its cyclic voltammetric curve in the anolyte is shown in the figure below. Figure 3 As shown, it exhibits electrochemical quasi-reversibility.

[0050] Two Nafion 115 cation exchange membranes were placed in an electrolytic cell, which was divided into an anode chamber, an intermediate chamber, and a cathode chamber. 100 ml of anolyte (0.1 M anthraquinone 2,7-disulfonic acid disodium salt (2,7-AQDS) + 0.5 M H₂SO₄), 100 ml of intermediate chamber solution (1 M NaAc), and 100 ml of cathode solution (1 M NaHCO₃) were placed in a 100 ml sealed tank. The temperature of the electrolytic cell and tank was set to 50 °C. A peristaltic pump circulated between the electrolytic cell and tank at a flow rate of 390 ml / min. H₂ was introduced into the reduction tower at a flow rate of 50 ml / min. After electrolysis, CO₂ was bubbled into the cathode region at a rate of 30 ml / min. A DC power supply was applied between the anode and cathode electrodes. The electrolysis reaction was powered by an external DC power supply (IT6932A, Itek). The temperature of the electrolytic cell and tank was set to 50 °C.

[0051] The current density was set to 10 mA / cm². 2 The initial voltage was 0.464V, and the average voltage over 24 hours was 0.793V. Figure 4 The electrolysis efficiency is 93.8%, and the energy consumption for mineralizing each ton of CO2 is 533.3 kW·h.

[0052] 10g of CaCO3 was added to 100ml of electrolyte in the intermediate chamber, and the mixture was stirred at 400rpm for 8 hours. Then, 28.4g of solid Na2SO4 was added, and the mixture was reacted at 500rpm for 2 hours. The suspension was then vacuum filtered. The filter residue was dried at 50℃, and its composition was analyzed by XRD. The XRD results are shown below. Figure 5As shown, the results indicate that the purity of CaSO4 is 99.4% and the conversion rate is 88.26%.

[0053] After electrolysis, a large amount of solid precipitated two hours after CO2 was introduced into the alkaline solution at the cathode. Its composition and purity were determined using XRD and TGA (e.g., ...). Figures 6-7 This proves that it is NaHCO3 with a purity of 99.18%.

[0054] The test results met expectations, verifying the feasibility of the three-chamber CO2 mineralization membrane electrolysis system of the present invention for the production of high-value-added carbonates.

[0055] Example 2 Based on the system of Example 1, two Nafion 115 cation exchange membranes were placed in an electrolytic cell, which was divided into an anode chamber, an intermediate chamber, and a cathode chamber. 100 ml of anolyte (0.1 M substance ② anthraquinone 2,6-disulfonic acid disodium salt (2,6-AQDS) + 0.5 M H2SO4), 100 ml of intermediate chamber solution (1 M NaAc), and 100 ml of cathode solution (1 M NaHCO3) were placed in a 100 ml sealed storage tank. The temperature of the electrolytic cell and the storage tank was set to 50°C. A peristaltic pump circulated between the electrolytic cell and the storage tank at a flow rate of 390 ml / min. H2 was introduced into the reduction tower at a flow rate of 50 ml / min. After electrolysis, CO2 was bubbled into the cathode region at a rate of 30 ml / min. A DC power supply was applied between the anode and cathode electrodes. The electrolysis reaction was powered by an external DC power supply (IT6932A, Itek). The temperature of the electrolytic cell and the storage tank was set to 50°C.

[0056] The current density was set to 10 mA / cm². 2 The initial voltage was 0.874V, and the average voltage over 24 hours was 1.036V. Figure 8 The electrolysis efficiency is 90.2%, and the energy consumption for mineralizing each ton of CO2 is 735.1 kW·h.

[0057] 10 g of CaCO3 was added to 100 ml of electrolyte in the intermediate chamber, and the mixture was stirred at 400 rpm for 8 h. Then, 28.4 g of solid Na2SO4 was added, and the mixture was reacted at 500 rpm for 2 h. The suspension was then vacuum filtered. The filter residue was dried at 50 °C, and its composition was analyzed by XRD, showing that the purity of CaSO4 was 99.3%.

[0058] After electrolysis, a large amount of solid was precipitated two hours after CO2 was introduced into the cathode alkaline solution. The composition and purity were tested by XRD and TGA, proving that it was NaHCO3 with a purity of 98.5%.

[0059] Comparative Example 1 Two Nafion 115 cation exchange membranes were placed in an electrolytic cell, dividing the cell into an anode chamber, an intermediate chamber, and a cathode chamber. A gas diffusion electrode was used as the anode. 100 ml of anolyte (0.5 M H₂SO₄), 100 ml of intermediate chamber solution (1 M NaAc), and 100 ml of cathode solution (1 M NaHCO₃) were placed in a 100 ml sealed tank. The temperature of the electrolytic cell and tank was set to 50 °C. A peristaltic pump circulated between the electrolytic cell and tank at a flow rate of 390 ml / min. H₂ was introduced into the gas diffusion electrode at a flow rate of 50 ml / min. A DC power supply was applied between the anode and cathode electrodes. The electrolysis reaction was powered by an external DC power supply (IT6932A, Itech). The temperature of the electrolytic cell and tank was set to 50 °C. The current density was set to 10 mA / cm². 2 They also continuously monitor and record the voltage variation patterns of the electrolytic cell.

[0060] Figure 9 For this comparative group, the example current density is 10 mA / cm². 2 The relationship between cell voltage and reaction time during electrolysis is shown. The initial voltage is 1.635V, the average voltage over 24 hours is 2.170V, the electrolysis efficiency is 91.3%, and the energy consumption per ton of CO2 mineralization is 1447.8kW·h. The energy consumption of this technology is much higher than that of the technology applied to the technical solution of this invention.

[0061] Comparative Example 2 A Nafion 115 cation exchange membrane was placed in an electrolytic cell, which was divided into an anode and a cathode chamber. 100 ml of anolyte (0.1 M anthraquinone 2,7-disulfonic acid disodium salt (2,7-AQDS) + 0.5 M H₂SO₄) and 100 ml of catholyte (1 M NaHCO₃) were placed in a 100 ml sealed tank. The temperature of the electrolytic cell and tank was set to 50 °C. A peristaltic pump circulated between the electrolytic cell and tank at a flow rate of 390 ml / min. The H₂ flow rate introduced into the external reduction tower was 50 ml / min. A DC power supply was applied between the anode and cathode electrodes. The electrolysis reaction was powered by an external DC power supply (IT6932A, Itech). The temperature of the electrolytic cell and tank was set to 50 °C. The current density was set to 10 mA / cm². 2 They also continuously monitor and record the voltage variation patterns of the electrolytic cell.

[0062] Figure 10 For this comparative example, the current density is 10 mA / cm². 2The relationship between cell voltage and reaction time during electrolysis is shown. The initial voltage was 1.009V, the average voltage over 24 hours was 1.183V, the electrolysis efficiency was 82.5%, and the energy consumption per ton of CO2 mineralization was 873.4 kW·h. It can be seen that the energy consumption of this technology is higher than that of the technology applied in this invention, and the system stability is poor.

[0063] In summary, the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates provided by this invention utilizes an external power supply to change the pH environment of the solutions at the anode and cathode. After electrolysis, the system connects to the intermediate chamber solution to dissolve calcite and the cathode liquid to mineralize CO2, thereby realizing solid waste treatment and the production of high-purity carbonates.

[0064] First, an acid (such as sulfuric acid or phosphoric acid) containing the reduced PCET reactant QH2 is added to the anode chamber of the system. A strong base-weak acid salt solution (such as sodium acetate) is added as a buffer to the intermediate chamber, and a saturated sodium bicarbonate solution is added to the cathode chamber. During electrolysis, hydrogen evolution reaction (2H₂O + 2e⁻) occurs at the cathode. - →H2+2OH - ,2OH - +2HCO3 - →2CO3 2- +2H2O), hydrogen gas is circulated to the reduction tower in the anode area and combines with PCET reactant Q (Q + H2 → QH2), where it is oxidized at the anode to form H + (QH2→Q+2H) + +2e - ), H + The solution passes through the first cation exchange membrane and enters the intermediate chamber to form an acetate-sodium acetate buffer system. The Na+ released from the ionization of the solution in the intermediate chamber... + The electrolyte enters the cathode chamber through a second cation exchange membrane to maintain the system's charge balance. After electrolysis, the intermediate chamber solution reacts with calcite (mainly calcium carbonate) to form calcium acetate (2HAc + CaCO3 → Ca(Ac)2 + H2O + CO2↑), and then reacts with sodium sulfate (mainly sodium sulfate) to form gypsum (mainly calcium sulfate) (Ca(Ac)2 + Na2SO4 → 2NaAc + CaSO4↓). The filtered liquid phase can be used again as the initial solution for the intermediate chamber. The cathode reacts with carbon dioxide to obtain sodium bicarbonate as a mineralization product (Na2CO3 + CO2 + H2O → 2NaHCO3↓). The filtered liquid phase can be used again as the initial electrolyte for the cathode chamber. The entire membrane electrolysis mineralization process operates in this cyclical manner.

[0065] This system creates conditions for subsequent calcite dissolution, gypsum production, and CO2 mineralization through membrane electrolysis. While achieving CO2 mineralization, it has the potential to treat solid waste and produce high-purity carbonate products. Furthermore, the reduction unit in the anode region prevents the formation of unstable three-phase interfaces inherent in the original hydrogen circulation system, avoiding the use of gas diffusion electrodes. Simultaneously, utilizing an asymmetric battery structure, hydrogen evolution occurs at the cathode, preventing losses caused by PCET reactants contacting oxygen and improving the system's electrolytic stability. In addition, the system introduces an intermediate chamber as a buffer, which not only mitigates proton entry into the cathode chamber, improving electrolysis current efficiency and reducing system energy consumption, but also enables the production of high-concentration acid. This allows for direct connection to the subsequent calcite dissolution process, avoiding the separation process between acid and PCET reactants, simplifying the system's process flow, and reducing the impact of PCET reactants on product purity.

[0066] The specific embodiments of the present invention are not limited to the methods described above. The above descriptions are merely preferred embodiments and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, adjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the principles and concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The application relates to a CO2 mineralization membrane electrolysis system, which comprises an electrolysis reactor and a power supply, wherein the electrolysis reactor comprises an anode chamber, an intermediate chamber and a cathode chamber; the pH environment of the solution at the anode and the cathode is changed by using an electrochemical PCET reaction and being powered by the power supply, so that the absorption of CO2 at the cathode and the generation of acid at the anode are promoted, H + The production of acid in the intermediate chamber is realized, and the natural mineral or alkaline solid waste is recycled by using high-concentration acid, so that the solid waste treatment and the production of high-purity carbonate are realized; the H2 generated at the cathode is used for reducing and regenerating the anode liquid outside the system, so that the CO2 mineralization membrane electrolysis can be continuously and stably operated.

2. The three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to claim 1, characterized in that, The process of recycling natural minerals or alkaline solid waste using high-concentration acids involves dissolving calcite in an intermediate chamber solution after electrolysis and mineralizing CO2 in the cathode liquid, thereby achieving solid waste treatment and the production of high-purity carbonates.

3. The three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to claim 1, characterized in that, An acid containing reduced PCET reactant QH2 is added to the anode chamber of the electrolytic reactor, a strong base-weak acid salt solution is added to the intermediate chamber as a buffer, and a saturated sodium bicarbonate solution is added to the cathode chamber. During electrolysis, a hydrogen evolution reaction occurs at the cathode, and hydrogen gas is circulated to the reduction tower in the anode area to combine with PCET reactant Q, and is oxidized at the anode to form H. + H + The solution passes through the first cation exchange membrane and enters the intermediate chamber to form an acetate-sodium acetate buffer system. The Na+ released from the ionization of the solution in the intermediate chamber... + It enters the cathode chamber through the second cation exchange membrane to maintain the charge balance of the system; After electrolysis, the solution in the intermediate chamber reacts with calcite to form calcium acetate, and then reacts with sodium sulfate to form gypsum. The filtered liquid phase is used again as the initial solution in the intermediate chamber. The cathode reacts with carbon dioxide to obtain sodium bicarbonate as a mineralization product, and the filtered liquid phase is used again as the initial electrolyte in the cathode chamber.

4. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, In any one of the claims 1 to 3, the H2 carrier for the redox reaction in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste can be replaced with organic PCET reactants.

5. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The assembly method of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to any one of claims 1 to 3 is adaptable to different environments; under the premise that the buffer system meets the production conditions, a weak acid system can be directly used as the anolyte, and the electrolysis cell can be modified into a two-chamber system through an extraction process.

6. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The anolyte acid in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to any one of claims 1 to 3 is not limited to sulfuric acid, but also includes any one of hydrochloric acid and phosphoric acid.

7. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The electrochemical PCET reactants used in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to any one of claims 1 to 3 include quinones, tungstic acid, pyridines, phenazines, and their derivatives.

8. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The electrolyte added to the cathode chamber of the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to any one of claims 1 to 3 is saturated sodium bicarbonate, but it can also be replaced with other salts or alkaline solutions.

9. A three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, characterized in that, The CO2 mineralization process in the three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste according to any one of claims 1 to 3 includes the use of pure CO2 gas or impure CO2 gas.

10. A three-chamber CO2 mineralization membrane electrolysis method for producing high-purity carbonates from solid waste, characterized in that, include: Step 1: Construct a three-chamber CO2 mineralization membrane electrolysis system for producing high-purity carbonates from solid waste, as described in any one of claims 1 to 3; Step 2: Based on this system, complete the CO2 mineralization membrane electrolysis for producing high-purity carbonates from solid waste.

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