Electrolysis device for hydrogen peroxide production and simultaneous carbon dioxide capture, and method for hydrogen peroxide production and simultaneous carbon dioxide capture using same

Abstract

Provided is an electrolysis device for hydrogen peroxide production and carbon dioxide capture according to one aspect. The electrolysis device comprises: a reduction electrode reaction chamber including a reduction electrode; an oxidation electrode reaction chamber including an oxidation electrode; a separation membrane which selectively permeates charges and ionic species between the reduction electrode reaction chamber and the oxidation electrode reaction chamber; an oxygen supply unit for supplying oxygen to the reduction electrode; and a carbon dioxide supply unit for supplying carbon dioxide to the reduction electrode, wherein the reduction electrode is a gas diffusion electrode (GDE) including a hydrophobic carbon catalyst layer.

Description

Electrolytic device for producing hydrogen peroxide and capturing carbon dioxide simultaneously and method for producing hydrogen peroxide and capturing carbon dioxide simultaneously using the same

[0001] The present invention relates to an electrolytic device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, and a method for producing hydrogen peroxide and capturing carbon dioxide simultaneously using the same.

[0002] Hydrogen peroxide (H2O2) is a crucial compound in chemical synthesis and water treatment processes. The anthraquinone process is a representative process for producing hydrogen peroxide. However, it is expensive, environmentally unfriendly, and hazardous due to the use of expensive hydrogen gas, toxic organic solvents, and a precious metal, palladium, as a catalyst. To address these issues, electrochemical hydrogen peroxide synthesis via oxygen reduction has been proposed.

[0003] Carbon dioxide (CO2) is a greenhouse gas emitted today from all aspects of human activity, including energy production. Due to growing concerns about global warming and climate change, related policies are being continuously strengthened. Consequently, the development of carbon capture, utilization, and storage (CCUS) technologies is also actively underway worldwide.

[0004] Carbon capture, utilization, and treatment technologies are broadly divided into carbon capture and storage (CCS) and carbon capture and recycling (CCU). CCS, which includes direct air capture (DAC) and absorption / adsorption, offers the advantage of substantially reducing carbon dioxide emissions, but there are still significant areas for improvement in practical application. CCU, which includes carbon dioxide reduction (CO2RR), has the advantage of converting atmospheric carbon dioxide into useful compounds and recycling it as a resource. However, converting carbon dioxide, the end product of combustion, requires significantly high cell potentials. While active research is being conducted in the field of CO2RR to convert carbon dioxide into a resource, continued advancements in negative emission technologies (NETs) are necessary to achieve net zero and the practical removal of carbon dioxide from the atmosphere.

[0005] In this regard, the advancement of CCS technologies, such as DAC and absorption / adsorption, is essential. While DAC technology is steadily improving through ongoing research and the introduction of electrochemical technologies, it still faces significant limitations. A key issue is that DAC typically requires a very high pH, ​​typically >14. This requires a significant supply of hydroxide ions, which in turn requires lowering the pH during the carbon dioxide separation process. This ultimately increases the unit cost of the process.

[0006] The present invention provides an electrolytic device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, and an effective method for producing hydrogen peroxide and capturing carbon dioxide simultaneously using the same.

[0007] An electrolysis device for producing hydrogen peroxide and capturing carbon dioxide simultaneously according to the sun is provided. The electrolysis device comprises:

[0008] A reduction electrode reactor including a reduction electrode;

[0009] An oxidation electrode reactor including an oxidation electrode;

[0010] A separation membrane selectively permeating charge and ion species between the reduction electrode reaction tank and the oxidation electrode reaction tank;

[0011] An oxygen supply unit that supplies oxygen to the above reduction electrode; and

[0012] A carbon dioxide supply unit for supplying carbon dioxide to the above reduction electrode;

[0013] The above reduction electrode is a gas diffusion electrode (GDE) including a hydrophobic carbon catalyst layer.

[0014] Another method for producing hydrogen peroxide and capturing carbon dioxide simultaneously according to the sun is provided. The method

[0015] A reduction electrode reactor including a reduction electrode;

[0016] An oxidation electrode reactor including an oxidation electrode;

[0017] A separation membrane selectively permeating charge and ion species between the reduction electrode reaction tank and the oxidation electrode reaction tank;

[0018] An oxygen supply unit that supplies oxygen to the above reduction electrode; and

[0019] A carbon dioxide supply unit for supplying carbon dioxide to the above reduction electrode;

[0020] A step of providing an electrolysis device in which the above reduction electrode is a gas diffusion electrode including a hydrophobic carbon catalyst layer;

[0021] A step of accommodating an electrolyte in the reduction electrode reaction tank and the oxidation electrode reaction tank;

[0022] A step of supplying oxygen and carbon dioxide to the gas diffusion electrode through the oxygen supply unit and the carbon dioxide supply unit; and

[0023] It includes a step of performing electrolysis by applying current or voltage to the reduction electrode and the oxidation electrode.

[0024] According to the present invention, a high-concentration hydrogen peroxide can be produced while simultaneously effectively capturing carbon dioxide using an electrolytic device utilizing a carbon-based gas diffusion electrode. Furthermore, when seawater is used as an electrolyte, the captured carbon dioxide can be mineralized at room temperature while simultaneously producing high-concentration chlorine.

[0025] Figure 1 is a diagram conceptually illustrating the operating principle of an electrolysis device for simultaneous production of hydrogen peroxide and capture of carbon dioxide according to one embodiment.

[0026] Figure 2 is a flowchart showing a method for producing hydrogen peroxide and simultaneously capturing carbon dioxide according to one embodiment.

[0027] Figure 3 is a diagram showing the speciation and reaction path of carbon dioxide in the electrolyte of the electrolysis device of the present invention.

[0028] Figure 4a is a photograph of the reaction time of a reduction electrode reaction tank including a pH indicator of an electrolysis device, and Figure 4b is a photograph of an enlarged portion of the reduction electrode in Figure 4a.

[0029] Figure 5 is a series of photographs showing the colors of twelve sodium perchlorate aqueous solutions with different pHs and containing a pH indicator.

[0030] Figures 6a to 6d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte after electrolysis, the bulk pH of the reduction electrode reaction tank electrolyte, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Example 1 and Comparative Example 1, respectively.

[0031] Figure 7 is a graph comparing the amount of carbon dioxide dissolved in the electrolyte in Comparative Example 2 and Example 1.

[0032] Figures 8a to 8d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte after electrolysis, the bulk pH of the reduction electrode reaction tank electrolyte, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Examples 2 to 4, respectively.

[0033] Figures 9a to 9d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte after electrolysis, the bulk pH of the reduction electrode reaction tank electrolyte, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Examples 1 and 2, respectively.

[0034] Figures 10a to 10d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte after electrolysis, the bulk pH of the reduction electrode reaction tank electrolyte, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Examples 2 and 5 and Comparative Example 3, respectively.

[0035] Figure 11 shows the current density of 10 mA / cm in Example 5 and Comparative Example 3. 2 This is a photo of a gas diffusion electrode after 30 minutes of electrolysis.

[0036] Figure 12 shows the current density of 10 mA / cm in Example 5 and Comparative Example 3. 2 These are SEM photographs of the surface of the gas diffusion electrode after 30 minutes of electrolysis and the surface of the unused gas diffusion electrode (Comparative Example 4) manufactured in Example 1.

[0037] Figures 13 and 14 are XRD graphs of precipitates in the electrolyte of the reduction electrode reaction tank of Example 5 and Comparative Example 3, respectively, using seawater electrolyte.

[0038] Figures 15a to 15d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte after electrolysis, the bulk pH of the reduction electrode reaction tank electrolyte, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Example 5 and Comparative Example 5, respectively.

[0039] Figure 16 is an XRD graph of the precipitate in the electrolyte of the reduction electrode reaction tank of Comparative Example 5.

[0040] Figures 17a and 17b are graphs comparing the changes in the concentration of calcium ions and magnesium ions in the reduction electrode reaction tank after electrolysis in Comparative Examples 3 and 5, respectively.

[0041] Figure 18 is a graph showing the change in the concentration of chloride ions in the reduction electrode reaction tank and oxidation electrode reaction tank after electrolysis in Comparative Example 5, analyzed using ion chromatography.

[0042] Figure 19 is a graph measuring the mass of mineral carbonation products (sediment) obtained according to the electrolysis time in Comparative Example 5.

[0043] Hereinafter, an electrolytic device for producing hydrogen peroxide and simultaneously capturing carbon dioxide according to implementation examples and a method for producing hydrogen peroxide and simultaneously capturing carbon dioxide using the same are described in detail.

[0044] (Electrolysis device for simultaneous production of hydrogen peroxide and capture of carbon dioxide)

[0045] FIG. 1 is a conceptual diagram illustrating an electrolysis device for simultaneous production of hydrogen peroxide and capture of carbon dioxide according to one embodiment. Referring to FIG. 1, an electrolysis device (100) for simultaneous production of hydrogen peroxide and capture of carbon dioxide includes a reaction tank (10), a reduction electrode (20), an oxidation electrode (30), a separation membrane (40), a power supply device (50), an oxygen supply unit (80a), and a carbon dioxide supply unit (80b). In one embodiment, the electrolysis device (100) may further include a chamber or a mixed gas supply unit (70) for delivering oxygen and carbon dioxide to the reduction electrode (20). Oxygen and carbon dioxide may be mixed in the mixed gas supply unit (70) and supplied to the reduction electrode (20).

[0046] The reaction tank (10) is a container that accommodates an electrolyte (60) and to which a reduction electrode (20) and an oxidation electrode (30) are connected. In one embodiment, the reaction tank (10) includes a reduction electrode reaction tank (10a) in which a reduction electrode (20) is placed and an oxidation electrode reaction tank (10b) in which an oxidation electrode (30) is placed, and the reduction electrode reaction tank (10a) and the oxidation electrode reaction tank (10b) can be separated by a separation membrane (40).

[0047] The reduction electrode reaction tank (10a) may accommodate a reduction electrode electrolyte (60a), and the oxidation electrode reaction tank (10b) may accommodate an oxidation electrode electrolyte (60b). In one embodiment, both the reduction electrode electrolyte (60a) and the oxidation electrode electrolyte (60b) may contain seawater. In another embodiment, the reduction electrode electrolyte (60a) and the oxidation electrode electrolyte (60b) may contain various industrial wastewaters such as concentrated seawater and brine.

[0048] The reduction electrode (20) is an electrode where oxygen is reduced through a proton reduction reaction to produce hydrogen peroxide. The reduction electrode (20) may be a carbonaceous gas diffusion electrode (GDE). A carbonaceous gas diffusion electrode refers to a gas diffusion electrode whose surface is made of (or coated with) an inorganic carbon material such as carbon black. The carbonaceous gas diffusion electrode can promote a proton reduction reaction to enable the production of high-concentration hydrogen peroxide. As hydrogen peroxide is actively produced, a local pH increase effectively occurs on the surface of the carbonaceous gas diffusion electrode, which can facilitate the absorption of carbon dioxide into the electrolyte.

[0049] The carbonaceous gas diffusion electrode of the reduction electrode (20) may be, for example, an electrode having an inorganic carbon catalyst layer (22) formed on the surface of a porous gas diffusion layer (21). The porous gas diffusion layer (21) may be formed, for example, of nickel foam. The porous gas diffusion layer (21) may be formed, for example, by overlapping and compressing a plurality of nickel foams. For example, the gas diffusion layer (21) may be formed by overlapping 5 to 10 sheets of nickel foam and compressing them using a hot press. An inorganic carbon catalyst layer (22) may be formed on one surface of the gas diffusion layer (21) to form the carbonaceous gas diffusion electrode of the reduction electrode (20). The inorganic carbon catalyst layer (22) may be, for example, a carbon black layer.

[0050] In one embodiment, the inorganic carbon catalyst layer (22) may be hydrophobic. The inorganic carbon catalyst layer (22) may include a hydrophobic binder to have hydrophobicity. The hydrophobic binder may include, but is not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP), or a combination thereof.

[0051] Since the inorganic carbon catalyst layer (22) has hydrophobicity, it allows gaseous reactants (oxygen and carbon dioxide) to directly contact the reduction electrode surface over a wide area, thereby reducing the material transfer limit to the electrode surface and significantly increasing the reaction rate at the reduction electrode.

[0052] Referring to Fig. 1, oxygen supplied from an oxygen supply unit (80a) passes through a gas diffusion layer (21) of a reduction electrode (20) and receives electrons from an inorganic carbon catalyst layer (22), and hydrogen peroxide can be generated through a previous oxygen reduction reaction as shown in the following reaction formula.

[0053] O2+ 2H + + 2e － → H2O2

[0054] Meanwhile, carbon dioxide supplied from the carbon dioxide supply unit (80b) passes through the gas diffusion layer (21) of the reduction electrode (20) and forms carbonic acid ions, i.e., bicarbonate ions (HCO3) in the electrolyte (60a), as shown in the following reaction formula. － ) or carbonate ions (CO3 2－ ) can be dissolved.

[0055] CO2+ H2O → HCO3 － + H + → CO3 2－ + 2H +

[0056] Meanwhile, in addition to the oxygen supply unit (80a) and the carbon dioxide supply unit (80b), an inert gas supply unit such as nitrogen may be further included. The inert gas may, for example, serve to control the ratio of oxygen and carbon dioxide.

[0057] Due to the favorable hydrogen peroxide production reaction by using the carbonaceous gas diffusion electrode according to the embodiment of the present invention, the electrolyte on the surface of the reduction electrode (20) can locally increase in pH to about 13 or more. The higher the pH of the solvent, the higher the solubility of carbon dioxide. Since carbon dioxide passes through the reduction electrode (20), which is a gas diffusion electrode, and comes into contact with the reduction electrode (20) and is injected into the reduction electrode electrolyte (60a) having a locally high pH, ​​the solubility of carbon dioxide in the electrolyte (60a) increases, and the amount of carbon dioxide captured in the form of ions in the reduction electrode electrolyte (60a) can increase.

[0058] In addition, when seawater is used as the electrolyte (60), carbon dioxide dissolved in the reduction electrode electrolyte (60a) such as hydrogen carbonate ions or carbonate ions can react with mineral ions such as calcium ions, which are dissolved components in the reduction electrode electrolyte (60a), to form a precipitate of carbonate such as calcium carbonate. The concentration of hydrogen carbonate ions or carbonate ions in the reduction electrode electrolyte (60a) decreases due to the formation of the carbonate precipitate, thereby promoting the capture of carbon dioxide in the reduction electrode electrolyte (60a). That is, when seawater is used as the electrolyte (60), carbon dioxide dissolved in the reduction electrode electrolyte (60a) can be solidified by mineral carbonation as described above (a mineral carbonation material is generated), which can be advantageous for the separation and storage of carbon dioxide.

[0059] Meanwhile, the porous structure of the gas diffusion electrode (20), which is a reduction electrode, facilitates the diffusion and dispersion of gas into the electrolyte. The use of the gas diffusion electrode ensures a uniform and smooth supply of oxygen, minimizing the influence of the oxygen transfer rate on the hydrogen peroxide production reaction, and also allows carbon dioxide to diffuse evenly into the electrolyte.

[0060] Conventional direct air capture (DAC) of carbon dioxide requires a very high solution pH of approximately 14, requiring a significant supply of hydroxide ions. This, in turn, requires lowering the solution pH during the subsequent carbon dioxide separation process. Furthermore, solvents used for DAC are vulnerable to oxygen and require additional equipment for temperature and pressure control.

[0061] In comparison, the present invention utilizes the active electron-oxygen reduction ability of a carbonaceous gas diffusion electrode to induce a high local pH in the electrolyte on the surface of the reduction electrode, thereby promoting carbon dioxide capture while maintaining the bulk pH of the electrolyte at a relatively low level, thereby reducing the cost of carbon dioxide capture and increasing the efficiency of the process.

[0062] In addition, the carbonaceous gas diffusion electrode used in the present invention does not require advanced catalyst synthesis technology, so it has high potential for mass production, and additionally, it has high potential for scale-up and integration with other processes, so that it can be applied in a wider range of industrial fields.

[0063] When seawater is used as the electrolyte (60), the seawater, which is the oxidation electrode electrolyte (60b), can be oxidized at the oxidation electrode (30) to produce oxygen and hydrogen ions. The production of hydrogen ions lowers the pH of the oxidation electrode electrolyte (60b). In addition, chlorine ions, which account for the highest proportion among the dissolved components in seawater, can be oxidized at the oxidation electrode (30) to produce chlorine gas and chlorine water containing the same. In addition, the produced chlorine can exist in the form of chlorine gas in an acidic region and hypochlorous acid in a weakly acidic to neutral region. Chlorine is a component of widely used disinfectants, and therefore, the electrolysis device according to the present invention can produce chlorine, which is a useful substance, in addition to producing hydrogen peroxide and capturing and storing carbon dioxide.

[0064] The reaction tank (10) may include a separation membrane (40) between the reduction electrode (20) and the oxidation electrode (30). That is, the reduction electrode reaction tank (10a) and the oxidation electrode reaction tank (10b) may be separated by the separation membrane (40). The separation membrane (40) may be any suitable commercially available ion exchange membrane, including, for example, an anion exchange membrane and a cation exchange membrane. The separation membrane (40) may selectively allow charges and hydrogen ions to pass through, but may have difficulty allowing hydrogen peroxide, which has a relatively large molecular size, to pass through, thereby preventing the hydrogen peroxide generated at the reduction electrode (20) from being decomposed again at the oxidation electrode (30). Meanwhile, when carbon dioxide captured in the reduction electrode reaction tank (10a) moves to the oxidation electrode reaction tank (10b), the oxidation electrode reaction tank (10b) has a lower pH environment than the reduction electrode reaction tank (10a) due to the oxidation reaction, so it may be released as a gas. At this time, the movement of carbon dioxide in the reduction electrode reaction tank (10a) to the oxidation electrode reaction tank (10b) is restricted by the separation membrane (40), thereby preventing the release of the captured carbon dioxide. In addition, when seawater is used as the electrolyte (60), carbon dioxide and mineral ions contained in the reduction electrode electrolyte (60a) react in the reduction electrode reaction tank (10a) to form a carbonate precipitate, so that carbon dioxide may be fixed in the reduction electrode electrolyte (60a).

[0065] In one implementation example, when a reference electrode is used in the reaction tank (10), a more precise evaluation of the electrolysis device, such as energy consumption, becomes possible.

[0066] (Electrolytic method for producing hydrogen peroxide and simultaneously capturing carbon dioxide)

[0067] Figure 2 is a flowchart sequentially showing an electrolysis method for producing hydrogen peroxide and simultaneously capturing carbon dioxide using the electrolysis device described above.

[0068] Referring to Fig. 2, an electrolytic cell for simultaneous production of hydrogen peroxide and capture of carbon dioxide is configured (S10). For this purpose, an electrolysis device according to the aforementioned embodiment can be used. As described above, a carbonaceous gas diffusion electrode can be used as a reduction electrode. An electrolyte is contained in a reduction electrode reaction tank and an oxidation electrode reaction tank. In one embodiment, seawater can be contained as the electrolyte. In another embodiment, various industrial wastewaters, such as seawater concentrate discharged from processes such as seawater desalination and brine, a byproduct of a salt plant, can be used as the electrolyte.

[0069] Oxygen and carbon dioxide are supplied to the reduction electrode gas diffusion electrode (S20). Oxygen may be supplied at a flow rate ranging from, for example, 50 mL / min to 500 mL / min, for example, 100 mL / min to 400 mL / min, for example, 150 mL / min to 300 mL / min, but is not limited thereto. Carbon dioxide may be supplied at a flow rate ranging from, for example, 1 mL / min to 500 mL / min, for example, 10 mL / min to 400 mL / min, for example, 30 mL / min to 300 mL / min, but is not limited thereto. Meanwhile, an inert gas such as nitrogen may be selectively supplied to control the content ratio of oxygen or carbon dioxide, and the flow rates thereof may be appropriately selected. The total gas flow rate supplied to the reduction electrode may be, for example, in the range of about 50 mL / min to about 1000 mL / min, for example, in the range of about 100 mL / min to about 500 mL / min, for example, in the range of about 200 mL / min to about 400 mL / min, but is not limited thereto. In the present embodiment, a case where oxygen and carbon dioxide are supplied at independent flow rates has been described, but in other embodiments, these gases may be mixed in advance and the flow rate of the mixed gas may be controlled and injected, and in this case, an inert gas such as nitrogen and / or a trace amount of other types of gases may be included.

[0070] The flow rate of gas supplied to the gas diffusion electrode, which is a reduction electrode, can be adjusted to an appropriate range depending on the applied current and / or voltage, the intensity of the oxygen reduction reaction, the purity (concentration) of the injected carbon dioxide gas, etc.

[0071] Since the reduction electrode is a gas diffusion electrode, oxygen and carbon dioxide can diffuse and disperse smoothly and evenly into the electrolyte through the gas diffusion electrode, thereby improving hydrogen peroxide production and carbon dioxide dissolution. Furthermore, the carbonaceous gas diffusion electrode facilitates the smooth proton reduction reaction of oxygen.

[0072] Apply voltage or current to the electrolysis device (S30). At this time, the current density flowing through the electrolysis device is, for example, 1 mA / cm 2 Within 100 mA / cm 2 or 5 mA / cm 2 50 mA / cm 2 or 10 mA / cm 2 20 mA / cm 2 This can be achieved by applying voltage or flowing current, but is not limited thereto. The voltage or current value can be changed by calculating the current density required to achieve the desired concentration of hydrogen peroxide or dissolved carbon dioxide within a desired time.

[0073] When voltage is applied or current flows to the electrolysis device, oxygen supplied to the gas diffusion electrode, which is a reduction electrode, undergoes a diatomic reduction reaction on the surface of the gas diffusion electrode to produce hydrogen peroxide, and the dissolution of carbon dioxide supplied to the gas diffusion electrode into the electrolyte is promoted (S40).

[0074] The faradaic efficiency for producing hydrogen peroxide by electrolysis according to the present embodiment may be 60% to 100%, 70% to 100%, or 80% to 100%. Additionally, the energy consumed to produce 1 kg of hydrogen peroxide by the electrolysis may be 3 kWh to 30 kWh, 4 kWh to 20 kWh, 4 kWh to 15 kWh, or 4 kWh to 10 kWh.

[0075] As hydrogen peroxide is produced, the electrolyte around the reduction electrode consumes hydrogen ions, locally increasing the pH. Then, the decrease in hydrogen ions gradually spreads to the electrolyte inside the reduction electrode reaction vessel, so that the pH of the entire reduction electrode electrolyte also increases. The electrolyte around the reduction electrode and the electrolyte inside the reduction electrode reaction vessel can have strong alkalinity. For example, the electrolyte in the part in contact with the reduction electrode can have a local pH of pH 13 or higher, and the electrolyte inside the reduction electrode reaction vessel can have a value of about pH 10 to 12 under conditions without carbon dioxide and a value of about pH 7.5 to 10 under conditions where carbon dioxide is absorbed. The higher the concentration of hydrogen peroxide produced, the higher the local pH of the electrolyte around the reduction electrode can become. Since carbon dioxide is more soluble in solutions with high pH, ​​the higher the efficiency of hydrogen peroxide production, the higher the solubility of carbon dioxide in the electrolyte, which can increase the carbon dioxide absorption rate. Meanwhile, the pH of the electrolyte located a certain distance from the reduction electrode (i.e., bulk pH) decreases compared to the pH of the electrolyte near the reduction electrode. For example, the bulk pH of the reduction electrode electrolyte can range from approximately 7.5 to 10. Carbon dioxide can be absorbed into the electrolyte and stored in an ionic state. After carbon dioxide undergoes speciation into an ionic state within the electrolyte, it can remain stable even at relatively low pH.

[0076] Figure 3 is a diagram showing the speciation and reaction path of carbon dioxide in the atmosphere and water system to explain the promotion of carbon dioxide dissolution into the electrolyte in the present invention. At the reduction electrode of the electrolysis device of the present invention, first, hydrogen peroxide, a reaction product, is produced by the electron reduction reaction, along with hydroxide ions (OH) as a byproduct. - ) is generated. In the present invention, since the transfer of oxygen molecules is improved by utilizing a carbonaceous gas diffusion electrode, the electron reduction reaction is further promoted. The high local pH region near the surface of the reduction electrode becomes more basic due to this active electron reduction reaction, and since the supply of the mixed gas is made through the carbonaceous gas diffusion electrode, the location of carbon dioxide supply and the location of formation of locally high pH coincide. In a non-alkaline environment, the speciation of carbon dioxide proceeds by a slow reaction called hydration (Reaction 1), but in the present invention, carbon dioxide (CO2(aq)) dissolved in the electrolyte can directly react with hydroxide ions locally concentrated on the surface of the carbonaceous gas diffusion electrode (Reaction 3). This reaction is a very fast reaction compared to the hydration reaction, and the carbonaceous gas diffusion electrode can increase the local concentration of hydroxide ions (local pH) faster than other types of electrodes, resulting in the promotion of carbon dioxide capture, and the captured carbon dioxide can then be converted into carbonate (hydrogen) ions and stored in the electrolyte of the reduction electrode reactor. Since the hydroxide ions generated by the carbonaceous gas diffusion electrode gradually diffuse into the electrolyte of the reduction electrode reactor, the carbonate (hydrogen) ions stored in this way can be stably stored in an alkaline environment.

[0077]

[0078] The absorption and storage of carbon dioxide in an alkaline aqueous solution follows the speciation of carbon dioxide, and since hydroxide ions are directly or indirectly involved in the individual reactions mentioned above, the equilibrium of substances in the system and the reaction rates of the related reactions are greatly affected by pH. However, for carbon dioxide absorption and capture through this process to be effective in an actual process, a very high pH is required. In fact, the carbon dioxide absorption process utilizing the currently commercialized direct air capture (DAC) technology requires a very high pH (>14). However, the present invention does not increase the pH of the entire absorption solution (reduction electrode reactor electrolyte) for carbon dioxide capture, but rather focuses on enhancing only the local pH of the area where absorption directly occurs (near the surface of the carbonaceous gas diffusion electrode) and directly utilizes this, thereby having the advantage of easier pH control compared to existing carbon dioxide absorption processes. In addition, the carbon dioxide absorption process of the present invention is insensitive to oxygen in the injected mixed gas, and is stable in water because it is based on an aqueous electrochemical system. Since many carbon dioxide capture processes have the limitation of being very sensitive to oxygen and water, the present invention has the advantage of being able to supplement or replace existing carbon dioxide capture processes that have such limitations.

[0079] Additionally, carbon dioxide in its ionic state can react with mineral ions, such as calcium ions, dissolved in seawater electrolytes, to form carbonate precipitates, such as calcium carbonate. In other words, carbon dioxide can be stored in the seawater electrolyte in both its ionic and solid form.

[0080] In addition, because the pH of the reduction electrode reactor is maintained in a relatively low alkaline range due to the buffering effect of carbon dioxide captured and stored within the electrolyte, the concern about decomposition of the generated hydrogen peroxide due to high alkaline pH can be reduced.

[0081] Meanwhile, during the electrolysis process of the present invention, the seawater electrolyte can be oxidized at the oxidation electrode to produce oxygen and hydrogen ions. Furthermore, chlorine ions, a dissolved component in seawater, can be oxidized to produce chlorine gas or chlorine water containing chlorine ions.

[0082] According to the electrolysis method of the present invention, by using a carbonaceous gas diffusion electrode as a reduction electrode, the electron-oxygen reduction reaction is promoted, thereby increasing the production efficiency of hydrogen peroxide, and as the production efficiency of hydrogen peroxide increases, the local pH of the carbonaceous gas diffusion electrode increases, thereby increasing the carbon dioxide capture efficiency. In addition, by using a gas diffusion electrode, the area of ​​contact between carbon dioxide and the electrolyte is increased, thereby further increasing the carbon dioxide capture efficiency. In addition, in the present embodiment, by using seawater as an electrolyte, mineral carbonation is promoted by the reaction of carbon dioxide captured in the electrolyte with mineral ions in seawater, thereby increasing the carbon dioxide capture efficiency, and chlorine gas useful in industry can be obtained by oxidation of chlorine ions in seawater at the oxidation electrode.

[0083] Example

[0084] Example of manufacturing a gas diffusion electrode

[0085] (1) Manufacturing of ink for carbon black catalyst

[0086] 1 g of carbon black (FuelcellStore) powder was mixed with 50 mL of ethanol and sonicated for 1 hour to mix. 1 mL of a PTFE (polytetrafluoroethylene) dispersion (60 wt%) was added to this mixture, sonicated for another hour, and then homogenized for 15 minutes to prepare a carbon black catalyst ink.

[0087] (2) Manufacturing of gas diffusion layer

[0088] After overlapping seven sheets of nickel foam, they were pressed at a pressure of 100 bar using a hot press to form a support, and then the outermost sheet of nickel foam on one side of the support was removed to produce a gas diffusion layer. Removing the outer nickel foam exposes the rough surface of the nickel foam, facilitating the subsequent formation of a catalyst layer.

[0089] (3) Formation of carbon black catalyst layer

[0090] The carbon black catalyst ink prepared in (1) was evenly applied to the rough surface of the nickel foam gas diffusion layer using an air gun so that the nickel foam was not exposed. The nickel foam electrode coated with the carbon black catalyst ink was dried on a hot plate at 120°C for about 3 minutes to remove the solvent in the ink, and sintered in a furnace at 270°C for 10 minutes. The coating, drying, and sintering of the carbon black catalyst ink were performed once more to form a carbon black catalyst layer on the gas diffusion layer. The gas diffusion layer on which the carbon black catalyst layer was formed was pressed at a pressure of 100 bar in a hot press at 100°C for 10 minutes. Thereafter, the side surfaces of the gas diffusion layer pressed in the hot press were coated with a hydrophobic adhesive (Pattex glue) having waterproofing capabilities to prevent unnecessary penetration of the injected gas and electrolyte, thereby completing the gas diffusion electrode on which the carbon black catalyst layer was formed.

[0091] Visualization of local pH and bulk pH of electrolytes

[0092] (1) Composition of electrolysis device

[0093] The gas diffusion electrode manufactured in the gas diffusion electrode manufacturing example was used as the reduction electrode of the electrolysis device (electrolytic cell), a platinum coil electrode was used as the oxidation electrode, and a saturated calomel electrode (SCE) was used as the reference electrode. A 50 mM sodium perchlorate aqueous solution containing a pH indicator (sodium orange II salt, 62.5 ppm) was used as the electrolyte.

[0094] The area of ​​the reduction electrode is 7 cm 2 The volume of the electrolyte in the reduction electrode reaction tank was 11 mL, and the volume of the electrolyte in the oxidation electrode reaction tank was 14 mL. The initial pH of the reduction electrode reaction tank was 6.28 (including pH indicator), and the initial pH of the oxidation electrode reaction tank was 6.24. An anion separation membrane (AMX from Neosepta) was used between the reduction electrode reaction tank and the oxidation electrode reaction tank.

[0095] (2) Operation of electrolysis device

[0096] Oxygen (O2) and nitrogen (N2) were supplied from the back of the gas diffusion electrode, which is the reduction electrode of the above electrolysis device, and the flow rates of oxygen (O2) and nitrogen (N2) supplied to the reduction electrode were approximately 50 mL / min each, and the reaction was initiated by flowing a constant current of 70 mA. The current density was 10.0 mA / cm 2 It was.

[0097] (3) Visualization of electrolyte pH

[0098] The reduction electrode reaction tank of the electrolysis device was photographed before and 3 seconds after the current was applied. Fig. 4a is a series of photographs of the reduction electrode reaction tank of the electrolysis device, including a pH indicator, over the course of reaction time, and Fig. 4b is an enlarged photograph of the reduction electrode portion in Fig. 4a. In Figs. 4a and 4b, (a) is a photograph before the current was applied, and (b), (c), (d), (e), and (f) are photographs taken 0.2 seconds, 0.6 seconds, 1.0 seconds, 2.0 seconds, and 3.0 seconds after the current was applied, respectively. Referring to Fig. 4a, the color of the electrolyte is orange, and overall, no change in the color of the electrolyte is noticeable, but the color on the left side of the reaction tank where the reduction electrode is located appears to gradually darken as the reaction time elapses. Referring to Fig. 4b, as the reaction time elapses, the color of the electrolyte around the reduction electrode begins to darken, and the dark-colored area gradually expands. However, referring to Fig. 4a, the dark-colored area of ​​the electrolyte appears to be limited to the area around the reduction electrode.

[0099] Twelve sodium perchlorate aqueous solutions having a pH range of 6.28 to 12.82 were prepared by adding 0.001N, 0.01N, 0.1N, and 1N NaOH solutions in amounts of 0 mL, 0.15 mL, or 0.30 mL to a sodium perchlorate aqueous solution containing 50.0 mM sodium perchlorate and 62.5 ppm Orange II sodium salt indicator.

[0100] The color and pH of the above 12 sodium perchlorate aqueous solutions are shown in Fig. 5 and Table 1, respectively. Referring to Fig. 5 and Table 1, it can be seen that the darker the color of the sodium perchlorate aqueous solution, the higher the pH. By comparing the photo of the reduction electrode reaction tank of Fig. 4b with the color of the sodium perchlorate aqueous solution of Fig. 5, the pH of the reduction electrode reaction tank of Fig. 4b can be inferred. In addition, it can be confirmed that the local pH of the reduction electrode surface is significantly higher than the bulk pH inside the reduction electrode reaction tank from the fact that the color of the electrolyte adjacent to the reduction electrode is much darker than the color of the electrolyte inside the reduction electrode reaction tank.

[0101] pH1a1b1c1d6.286.286.286.282a2b2c2d6.5710.2911.3512.63a3b3c3d6.8310.6411.6812.82

[0102]

[0103] Examples 1 to 5 and Comparative Examples 1 to 5

[0104] (1) Composition of electrolysis device

[0105] An electrolysis device was constructed as described above with reference to Fig. 1. The electrolysis device forms an electrolysis cell. The gas diffusion electrode manufactured in Example 1 was used as the reduction electrode of the electrolysis device, a platinum coil electrode was used as the oxidation electrode of the electrolysis device, and a saturated calomel electrode (SCE) was used as the reference electrode. The reduction electrode had an area of ​​7 cm. 2 And, an anion separation membrane (AMX from Neosepta) was used between the reduction electrode reaction tank and the oxidation electrode reaction tank.

[0106] (2) General electrolyte

[0107] For the general electrolyte, not seawater, a 50 mM sodium perchlorate aqueous solution was used. When the general electrolyte was used, the electrolyte volume of the reduction electrode reaction tank was 13 mL or 25 mL, and the electrolyte volume of the oxidation electrode reaction tank was 14 mL. The initial pH of the general electrolyte (reduction electrode electrolyte and oxidation electrode electrolyte) was 6.24. Perchloric acid (HClO4) and sodium hydroxide (NaOH) were used to adjust the initial pH to approximately 6.24.

[0108] (3) Seawater electrolyte

[0109] Seawater collected from Geojampo Beach, Incheon was used as a seawater electrolyte, and the collected seawater was passed through a 0.2 μm vacuum filter to remove impurities. The seawater electrolyte contained sodium ions (approximately 459.2 mM), magnesium ions (approximately 46.0 mM), calcium ions (approximately 7.9 mM), potassium ions (approximately 9.7 mM), chloride ions (approximately 535.4 mM), sulfate ions (approximately 27.6 mM), and bromine ions (approximately 0.8 mM). When seawater electrolyte was used, the electrolyte volume of the reduction electrode reaction tank was 25 mL, and the electrolyte volume of the oxidation electrode reaction tank was 14 mL. The initial pH of the seawater electrolyte (reduction electrode electrolyte and oxidation electrode electrolyte) was 7.98.

[0110] (4) Operation of electrolysis device

[0111] Oxygen and nitrogen or a mixture of oxygen, carbon dioxide, and nitrogen was supplied to the gas diffusion electrode (reduction electrode) at a flow rate of about 200 mL / min. The mixed gas passed through the gas diffusion electrode and was injected into the electrolyte of the reduction electrode reaction tank. The currents at the reduction electrode were 1.0, 2.5, 5.0, and 10.0 mA / cm. 2 Each electrolysis device was operated for 30 minutes for each current density. At this time, a current corresponding to the gas diffusion electrode, which is the working electrode (reduction electrode), was applied to have the above current density.

[0112] Example 1 (general electrolyte)

[0113] The general electrolyte of the above-mentioned sodium perchlorate aqueous solution was used as the electrolyte, and the volume of the electrolyte in the reduction electrode reaction tank was 13 mL. A mixture of oxygen: carbon dioxide: nitrogen with a flow ratio of 50:1:49 was used as the gas supplied to the reduction electrode. The current densities were 1.0, 2.5, 5.0, and 10.0 mA / cm 2 In each case, an electrolysis field was operated.

[0114] Comparative Example 1 (hydrogen peroxide production alone)

[0115] The electrolysis field was operated in the same manner as in Example 1, except that a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:0:50 was used instead of a flow rate ratio of 50:1:49 as the gas supplied to the reduction electrode.

[0116] Comparative Example 2 (Carbon Dioxide Capture Only)

[0117] Instead of 6.24, the initial pH of the electrolyte was 11, 12 and 13, and no current was applied to the electrolysis device (current density was 0 mA / cm). 2 ) was operated using the same method as in Example 1.

[0118] Example 2 (carbon dioxide concentration)

[0119] The electrolysis field was operated in the same manner as in Example 1, except that the volume of the reduction electrode reaction tank electrolyte was 25 mL instead of 13 mL.

[0120] Example 3 (carbon dioxide concentration)

[0121] The electrolysis field was operated in the same manner as in Example 2, except that a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:15:35 was used instead of a flow rate ratio of 50:1:49 as the gas supplied to the reduction electrode.

[0122] Example 4 (carbon dioxide concentration)

[0123] The electrolysis field was operated in the same manner as in Example 2, except that a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:50:0 was used instead of a flow rate ratio of 50:1:49 as the gas supplied to the reduction electrode.

[0124] Example 5 (seawater electrolyte)

[0125] An electrolysis cell was operated in the same manner as in Example 1, except that seawater was used instead of the general electrolyte of sodium perchlorate aqueous solution as the electrolyte. At this time, the volume of the electrolyte in the reduction electrode reaction tank was 25 mL.

[0126] Comparative Example 3 (Seawater Electrolyte & Hydrogen Peroxide Production Only)

[0127] The electrolysis field was operated in the same manner as in Example 5, except that a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:0:50 was used instead of a flow rate ratio of 50:1:49 as the gas supplied to the reduction electrode.

[0128] Comparative Example 4 (Gas Diffusion Electrode)

[0129] The gas diffusion electrode manufactured in the gas diffusion electrode manufacturing example was used for SEM imaging and EDS analysis.

[0130] Comparative Example 5 (Seawater Electrolyte & Damaged Electrode)

[0131] An electrolysis field was operated in the same manner as in Example 5, except that a damaged gas diffusion electrode was used instead of a normal gas diffusion electrode as the reduction electrode. The damaged gas diffusion electrode was formed by spraying water with high water pressure to cause the carbon black catalyst layer on the surface of the gas diffusion electrode to be lost.

[0132] Table 2 summarizes the conditions of Examples 1 to 5 and Comparative Examples 1 to 5.

[0133] GDE Electrolyte Source Reactor Electrolyte Volume (mL) O2:CO2:N2 Total Flow Rate (mL / min) Initial pH Example 1 Normal sodium perchlorate aqueous solution 1350:1:49 2006.24 Comparative Example 1 Normal sodium perchlorate aqueous solution 1350:0:50 2006.24 Comparative Example 2 Normal sodium perchlorate aqueous solution 1350:0:50 20011,12,13 Example 2 Normal sodium perchlorate aqueous solution 2550:1:49 2006.24 Example 3 Normal sodium perchlorate aqueous solution 2550:15:35 2006.24 Example 4 Normal sodium perchlorate aqueous solution 2550:50:0 2006.24 Example 5 Normal seawater 2550:1:49 2007.98 Comparison example 3 Normal seawater 2550:0:50 2007.98 Comparison example 4 Unused electrode-----Comparison example 5 Damaged electrode Seawater 2550:1:49 2007.98

[0134]

[0135] Evaluation method

[0136] (1) Measurement of the amount of carbon dioxide dissolved in the electrolyte

[0137] After 30 minutes of applying current to the electrolyzer, i.e., after 30 minutes of electrolysis, a sample was taken from the electrolyte in the cathode reactor, diluted with distilled water, and acid-treated simultaneously. Dilution and acid treatment were performed in a sealed headspace vial, and the concentration of carbon dioxide present in the headspace was measured by gas chromatography (Agilent Technologies 7820A GC System). By dissolving carbonate precipitates in the electrolyte by acid treatment, the contribution of carbonate precipitates to the amount of carbon dioxide dissolved in the electrolyte (absorbed amount) was included. Carbonate precipitates may be products formed when carbon dioxide dissolved in the electrolyte reacts with inorganic ions in seawater.

[0138] However, in the case of Comparative Example 2, the above-mentioned mixed gas was injected through the gas diffusion electrode for 30 minutes without applying current to the electrolysis device, and then the concentration of dissolved carbon dioxide in the electrolyte of the reduction electrode reaction tank was measured.

[0139] (2) Electrolyte pH measurement

[0140] After 30 minutes of electrolysis, a sample was taken from the cathode reactor electrolyte, and the bulk pH of the electrolyte was measured using a pH meter (Thermo Scientific Orion Star A Series). The cathode reactor electrolyte can be considered to have the same pH (bulk pH) except for a localized area on the cathode surface, and the bulk pH was measured at the electrolyte at the midpoint of the cathode reactor.

[0141] (3) Measurement of the faradaic efficiency of hydrogen peroxide production

[0142] The faradaic efficiency is the efficiency of an electrochemical reaction occurring at an electrode, and is the ratio of the amount of product actually produced during the reaction to the amount of product theoretically expected based on the amount of charge applied.

[0143] After applying current to the electrolysis device and 30 minutes, 0.2 to 1 mL of a sample was taken from the electrolyte of the reduction electrode reaction tank and diluted so that the concentration of hydrogen peroxide in the sample became 0.25 mM to 2 mM. Then, 1 mL of the diluted sample was mixed with 2 mL of an aqueous titanium sulfate solution, and the absorbance of the sample was measured at a wavelength of 405 nm using a colorimetric (titanium sulfate method) and a UV-VIS spectrophotometer. The absorbance value of the sample can be obtained using the molar absorbance value of the aqueous titanium sulfate solution used for the analysis. The amount of hydrogen peroxide generated was derived by measuring the absorbance, and the faradaic efficiency was obtained from the derived amount of hydrogen peroxide.

[0144] (4) Measurement of energy consumption per weight of hydrogen peroxide

[0145] The amount of hydrogen peroxide produced after 30 minutes of applying current to the electrolysis device and the energy consumed per weight of hydrogen peroxide (per 1 kg) were calculated from the energy consumed during this time. The energy consumed was calculated based on the applied current density and the effective area of ​​the reduction electrode (7 cm 2), was obtained using the cell voltage (voltage between the reduction electrode and the oxidation electrode) and reaction time (30 minutes) recorded in the electrostatic potential.

[0146] (5) XRD (X-ray diffraction) analysis

[0147] 10 mA / cm in Example 5, Comparative Example 3 and Comparative Example 5 2 After electrolysis was performed for 30 minutes under current density conditions, XRD analysis was performed on the precipitates formed in the reduction electrode or reduction electrode reactor using SmartLab (Rigaku).

[0148] (6) SEM imaging and EDS (Energy Dispersive X-Ray Spectrometer) analysis

[0149] 10 mA / cm in Example 5 and Comparative Example 3 2 After electrolysis was performed for 30 minutes under current density conditions, SEM imaging and EDS analysis were performed on the gas diffusion electrode. SEM imaging and EDS analysis were also performed on the gas diffusion electrode (Comparative Example 44) that was not used as a reference. JSM-7800F Prime (JEOL Ltd.) was used for EDS analysis.

[0150] (7) Measurement of changes in the concentration of calcium and magnesium ions

[0151] After electrolysis for 30 minutes, the changes in the concentration of calcium and magnesium ions in the reduction electrode reactor were measured using ion chromatography (Dionex AS-AP, Thermo Scientific).

[0152] (8) Measurement of sediment weight over time

[0153] The weight of the precipitate generated according to the electrolysis performance time was measured using the change in the weight of the reduction electrode and reduction reaction tank according to the progress of electrolysis. The mass measurement of the reduction electrode and reduction reaction tank was performed after sufficient drying in a dry oven for more than 12 hours.

[0154] Evaluation example

[0155] (1) Confirmation of integration of hydrogen peroxide production and carbon dioxide capture

[0156] Figures 6a to 6d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank after electrolysis, the bulk pH of the electrolyte of the reduction electrode reaction tank, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Example 1 and Comparative Example 1, respectively. In Example 1, a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:1:49 was used, and in Comparative Example 1, a mixed gas of oxygen:carbon dioxide:nitrogen with a flow rate ratio of 50:0:50 was used.

[0157] Referring to Fig. 6a, in Example 1, the amount of carbon dioxide dissolved in the electrolyte increased as the current density increased, whereas in Comparative Example 1, the amount of carbon dioxide dissolved in the electrolyte was 0 regardless of the current density. From this, it can be confirmed that the carbon dioxide supplied to the gas diffusion electrode, which is the reduction electrode, is captured in the electrolyte of the reduction electrode.

[0158] Referring to Fig. 6b, the bulk pH of the electrolyte of Example 1 is 2 to 4 lower than the bulk pH of the electrolyte of Comparative Example 1. This is believed to be because the local pH of the surface of the gas diffusion electrode increases due to the active proton reduction reaction (i.e., hydrogen peroxide production reaction) at the gas diffusion electrode, which is the reduction electrode of Example 1, and the capture of carbon dioxide supplied through the gas diffusion electrode in the electrolyte is promoted by this increased pH, and the capture of carbon dioxide causes the consumption (buffering effect) of hydroxide ions in the electrolyte.

[0159] Meanwhile, hydrogen peroxide generated by the previous electron oxygen reduction reaction is prone to reacting with hydroxide ions when the pH of the electrolyte is high, and thus has low stability. However, in the case of Example 1, since the bulk pH of the electrolyte was reduced compared to Comparative Example 1, the stability of the generated hydrogen peroxide is expected to be higher.

[0160] Referring to Fig. 6c, Example 1, in which hydrogen peroxide production and carbon dioxide capture were performed simultaneously, exhibited a higher faradaic efficiency of hydrogen peroxide production at all current densities than Comparative Example 1, in which only hydrogen peroxide production was performed. In other words, it was confirmed that Example 1 had a hydrogen peroxide production capability that surpassed that of Comparative Example 1.

[0161] In Fig. 6d, the Y-axis represents the energy consumed to produce 1 kg of hydrogen peroxide. Referring to Fig. 6d, the energy consumption calculated in Example 1 is similar to the energy consumption calculated in Comparative Example 1. This means that the energy consumption is satisfactory even though hydrogen peroxide production and carbon dioxide capture were performed simultaneously in Example 1 (i.e., two different processes were integrated).

[0162] From the comparison between Example 1 and Comparative Example 1, it can be confirmed that the integration of the hydrogen peroxide generation system and the carbon dioxide capture system according to the present invention not only effectively causes carbon dioxide capture, but also further increases the hydrogen peroxide generation capacity compared to a single hydrogen peroxide generation system (Comparative Example 1), and furthermore, no additional energy is consumed during the integration process.

[0163] (2) pH comparison for carbon dioxide absorption

[0164] Figure 7 is a graph comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank in Comparative Example 2 and Example 1. In Comparative Example 2, the initial pH value of the electrolyte (pH i ) For 11, 12, and 13, a mixture of oxygen:carbon dioxide:nitrogen was supplied to the gas diffusion electrode for 30 minutes without applying current. That is, in Comparative Example 2, only carbon dioxide capture was performed without electrolysis for producing hydrogen peroxide. The rightmost bar in Fig. 7 is the current density of 10 mA / cm in Example 1. 2In this case, the amount of carbon dioxide dissolved in the electrolyte is (see Fig. 6a). Referring to Fig. 7, in the case of Example 1, even though the initial pH of the electrolyte was 7.98, the amount of dissolved carbon dioxide (current density 10 mA / cm 2 The amount of carbon dioxide dissolved in a strong alkaline solution with an initial pH of 13 (about 50 mM) in Comparative Example 2 is higher than that of carbon dioxide dissolved in a strong alkaline solution with an initial pH of 13 (about 40 mM). That is, the current density of 10 mA / cm in Example 1 2 The amount of carbon dioxide dissolved in is expected to be comparable to the amount of carbon dioxide dissolved when the initial pH of the electrolyte of Comparative Example 2 is 14.

[0165] Also, in Comparative Example 2, when the initial pH was 12, the amount of dissolved carbon dioxide (about 6 mM) was 1 mA / cm in the current density of Example 1. 2 In this case, it appears to be smaller than the amount of carbon dioxide dissolved in the electrolyte (about 10 mM) (see Fig. 6a). In addition, referring to Fig. 6b, although the final bulk pH of the reduction electrode reaction tank electrolyte in Example 1 is all 10 or less, the amount of dissolved carbon dioxide is all greater than that of Comparative Example 2, which has an initial pH of 11 or more. It is inferred that the carbon dioxide capture ability of Example 1, in which the electron reduction reaction (hydrogen peroxide production) and carbon dioxide capture proceed simultaneously, is superior to that of Comparative Example 2, in which only carbon dioxide capture proceeds, due to the high local pH formed on the surface of the reduction electrode due to the active electron reduction reaction occurring at the gas diffusion electrode, which is the reduction electrode (see Figs. 4a and 4b).

[0166] (3) Comparison according to carbon dioxide supply amount

[0167] Figures 8a to 8d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank after electrolysis, the bulk pH of the electrolyte of the reduction electrode reaction tank, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Examples 2 to 4, respectively. In Examples 2 to 4, the flow rate ratio of carbon dioxide in the total mixed gas is 1%, 15%, and 50%, respectively.

[0168] Referring to FIGS. 8a and 8b, as the content of carbon dioxide in the mixed gas supplied to the gas diffusion electrode increases, the content of carbon dioxide dissolved in the electrolyte increases, and the bulk pH of the electrolyte decreases. In other words, as the content of carbon dioxide supplied increases, the amount of carbon dioxide captured increases. Referring to FIGS. 8c and 8d, in Examples 2 to 4, the faradaic efficiency of hydrogen peroxide production remains high without being significantly affected by the carbon dioxide content, and the energy consumption of hydrogen peroxide production also appears to be unaffected by the carbon dioxide content.

[0169] Although the data of Examples 2 to 4 were obtained using a general electrolyte, it can be inferred that even when a seawater electrolyte is used, the amount of carbon dioxide captured increases as the carbon dioxide content increases, just as in the case of using a general electrolyte, and that the faradaic efficiency and energy consumption of hydrogen peroxide production will not be significantly affected by the carbon dioxide content.

[0170] (4) Comparison according to the volume of electrolyte in the reduction electrode reaction tank

[0171] Figures 9a to 9d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank after electrolysis, the bulk pH of the electrolyte of the reduction electrode reaction tank, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Examples 1 and 2, respectively. In Examples 1 and 2, the electrolyte volume of the reduction electrode reaction tank is 13 mL and 25 mL, respectively. At this time, the area of ​​the reduction electrode is 7 cm.2 was the same as .

[0172] Referring to FIGS. 9a to 9d, the amount of captured and stored carbon dioxide is higher in Example 1, which uses a smaller volume of the reduction electrode reaction tank electrolyte, than in Example 2. The energy consumption for hydrogen peroxide production is higher in Example 2, which uses a larger volume of the reduction electrode reaction tank electrolyte, and this is believed to be due to the increased distance between the reduction electrode and the oxidation electrode due to the increased length of the reduction electrode reaction tank used in Example 2. From this, it can be inferred that the miniaturization of the system does not impair the performance of hydrogen peroxide production and carbon dioxide capture.

[0173] (5) Comparison by electrolyte

[0174] Figures 10a to 10d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank after electrolysis, the bulk pH of the electrolyte of the reduction electrode reaction tank, the faradaic efficiency of hydrogen peroxide production, and the energy consumption in Example 2, Example 5, and Comparative Example 3, respectively. In Example 5 and Comparative Example 3, a seawater electrolyte was used, and in Example 2, a general electrolyte of an aqueous sodium perchlorate solution was used. In Example 5 and Example 2, a mixed gas having a flow rate ratio of oxygen:carbon dioxide:nitrogen of 50:1:49 was used, and in Comparative Example 3, a mixed gas having a flow rate ratio of oxygen:carbon dioxide:nitrogen of 50:0:50 was used.

[0175] Referring to Fig. 10a, the carbon dioxide absorption amounts of Example 5 using seawater electrolyte and Example 2 using general electrolyte are not significantly different, and Example 2 appears to be slightly lower than Example 5.

[0176] Referring to Fig. 10b, in Examples 5 and 2 in which carbon dioxide capture is performed, Example 5 of the seawater electrolyte exhibits a lower bulk pH than Example 2 of the general electrolyte. This is believed to be because the types of ions contained in seawater are more diverse and have higher concentrations than those in the sodium perchlorate aqueous solution electrolyte. Meanwhile, the bulk pH of Comparative Example 3, in which no carbon dioxide was supplied and a seawater electrolyte was used, and Example 2, in which carbon dioxide was supplied and a general electrolyte was used, were lower than those of the seawater electrolyte at a current density of 2.5 mA / cm. 2 The values ​​are similar to those above, and it is believed that this is because the magnesium ions included in the seawater in Comparative Example 3 react with the hydroxide ions and reduce the concentration of the hydroxide ions.

[0177] Referring to Fig. 10c, the Faraday efficiency of hydrogen peroxide production in Example 5 using a seawater electrolyte is lower than that in Example 2 using a general electrolyte, and is higher than that in Comparative Example 3 using a seawater electrolyte but without simultaneous capture of carbon dioxide. From this, it was confirmed that even when a seawater electrolyte containing a large amount of minerals, as in Example 5, is used, the performance (Faraday efficiency) of a specific electrochemical reaction can be maintained at a significantly high level.

[0178] Referring to Fig. 10d, Example 5 and Comparative Example 3 using seawater electrolyte have lower energy consumption than Example 2 using a general electrolyte. From this, it can be seen that the use of seawater electrolyte can reduce the energy consumption of hydrogen peroxide production or hydrogen peroxide production and carbon dioxide capture. This is thought to be because the internal resistance of the electrolysis system is reduced due to the high conductivity of the components of the seawater electrolyte, thereby reducing energy consumption. Meanwhile, the energy consumption of Comparative Example 3, which uses seawater electrolyte like Example 5 but does not perform carbon dioxide capture, is higher than that of Example 5. This is thought to be because the concentration and electrical conductivity of the sodium perchlorate aqueous solution electrolyte are significantly lower than those of seawater.

[0179] (6) Comparison of deposits in gas diffusion electrodes

[0180] Figure 11 shows the current density of 10 mA / cm in Example 5 and Comparative Example 3. 2 This is a photograph of a gas diffusion electrode, which is a reduction electrode, after 30 minutes of electrolysis. Referring to Fig. 11, it is observed that serious surface deposits were formed in the gas diffusion electrode used in Comparative Example 3 (b), whereas the formation of surface deposits was clearly suppressed in the gas diffusion electrode used in Example 5 (a). The formation of deposits on the electrode surface causes a decrease in the performance of the electrochemical system. It can be inferred that the cause of the decrease in the faradaic efficiency of hydrogen peroxide production observed in Comparative Example 3 (see Fig. 10c) is due to the formation of deposits on the surface of the reduction electrode.

[0181] Figure 12 shows the current density of 10 mA / cm in Example 5 and Comparative Example 3. 2These are SEM photographs of the surface of the gas diffusion electrode, which is a reduction electrode, after 30 minutes of electrolysis and the surface of the unused gas diffusion electrode (Comparative Example 4) manufactured in the aforementioned gas diffusion electrode manufacturing example. Referring to Fig. 12, the surface (b) of the gas diffusion electrode of Example 5 appears similar to the surface (a) of the unused gas diffusion electrode of Comparative Example 4, but the surface (c) of the gas diffusion electrode of Comparative Example 3 shows a large difference in shade, unlike the surface (a) of the unused gas diffusion electrode of Comparative Example 4. This large difference in shade may be caused by vertical steps on the surface, and it is believed that the vertical steps on the surface are due to the formation of sediments on the electrode surface. Therefore, it can also be confirmed from the SEM photographs that sediments were formed on the surface of the gas diffusion electrode of Comparative Example 3.

[0182] Table 3 shows the results of EDS (Energy Dispersive X-Ray Spectrometer) analysis of the portions shown in the SEM images of the gas diffusion electrodes of Example 5 and Comparative Example 3 and the gas diffusion electrodes of Comparative Example 4.

[0183] Element Comparison Example 4 Example 5 Comparison Example 3 Atom % Atom % Atom % C86.0184.8831.87O--46.80 F12.5812.281.59Na--8.65 Mg--8.32 S0.150.130.17 Cl--0.60 K--0.75 Ca--0.76 Ni1.262.700.50 Total 100.00100.00100.00

[0184] Referring to Table 3, in Example 5 and Comparative Example 4 (unused gas diffusion electrode), only C, F, and Ni signals were significantly detected, which originated from carbon black powder, PTFE binder, and gas diffusion layer (Ni foam), respectively. On the other hand, in Comparative Example 3, high levels of O, C, Mg, and Na were detected simultaneously with Ca, F, Ni, K, and Cl. In Table 3, '-' indicates non-detection. From this, it can be seen that in Comparative Example 3, precipitation occurred on the surface of the catalyst layer of the gas diffusion electrode by operating a single electron reduction reaction (hydrogen peroxide production reaction) using a seawater electrolyte, and at the same time, various components in the seawater penetrated into the surface of the catalyst layer of the gas diffusion electrode. On the other hand, in Example 5, where hydrogen peroxide production and carbon dioxide capture were simultaneously performed despite the use of seawater electrolyte, damage to the catalyst layer of the gas diffusion electrode caused by the formation of sediment was significantly suppressed. (6) Comparison of sediments in the reduction electrode reaction tank electrolyte

[0185] Figures 13 and 14 are XRD graphs of precipitates in the electrolyte of the reduction electrode reaction tank of Example 5 and Comparative Example 3, respectively, using seawater electrolyte. Electrolysis in an electrolyte containing a large amount of mineral ions, such as seawater, can form precipitates in the reaction tank electrolyte or on the electrode surface. However, in the case of Example 5, precipitates were formed specifically in the electrolyte and not on the electrode surface, and in the case of Comparative Example 3, precipitates were formed both on the electrode surface and in the electrolyte.

[0186] Referring to Fig. 13, in Example 5, where hydrogen peroxide production and carbon dioxide capture were performed simultaneously, the main component of the precipitate included calcium carbonate (2-theta = 29.4°, 36.1°, 39.4°, 47.5°), which corresponds to a mineral carbonation product of mineral ions in seawater due to dissolved carbon dioxide. No magnesium precipitate was confirmed in the XRD graph of Example 5. On the other hand, referring to Fig. 14, in the case of Comparative Example 3, which is a single hydrogen peroxide production system, the main component of the precipitate was magnesium hydroxide (2-theta = 18.5°, 38.0°, 50.9°, 58.7°, 62.1°, 68.1°), and no separate mineral carbonation was observed.

[0187] As discussed above, since Example 5 has real-time mineral carbonation capability and excellent electrode surface deposit formation suppression capability, it can be seen that the present invention can significantly improve the stability of an electrolysis device in an environment where a large amount of mineral ions are included and serious electrode surface deposits and electrochemical performance reduction are a concern. In addition, the carbon dioxide capture process that proceeds simultaneously with hydrogen peroxide does not require separate energy input, but utilizes the high local pH of the reduction electrode surface formed by the production of hydrogen peroxide, and furthermore, the internal resistance reduction effect due to the high conductivity of seawater can be stably utilized, so it has an advantage in terms of energy usage compared to conventional technologies.

[0188] (7) Comparison according to damage to the gas diffusion electrode

[0189] Figures 15a to 15d are graphs comparing the amount of carbon dioxide dissolved in the electrolyte of the reduction electrode reaction tank after electrolysis, the bulk pH of the electrolyte of the reduction electrode reaction tank, the faradaic efficiency of hydrogen peroxide production, and the energy consumption of Example 5 and Comparative Example 5, respectively. In Comparative Example 5, hydrogen peroxide production and carbon dioxide capture were performed under the same conditions as Example 5, except that a damaged gas diffusion electrode was used.

[0190] Referring to Figures 15a to 15d, Comparative Example 5 showed a similar amount of dissolved carbon dioxide compared to Example 5, but the bulk pH of the reduction electrode reaction tank electrolyte (seawater electrolyte) was lower, and the faradaic efficiency of hydrogen peroxide production decreased and the energy consumption increased. In addition, in Comparative Example 5, as in Comparative Example 3, a significant amount of sediment was formed on the surface of the gas diffusion electrode (reduction electrode).

[0191] The decrease in the faraday efficiency of hydrogen peroxide production and the increase in energy consumption in Comparative Example 5 are believed to be due to the formation of deposits on the surface of the gas diffusion electrode, and the formation of the deposits is believed to be due to a damaged gas diffusion electrode. In the damaged gas diffusion electrode, the catalyst layer in contact with the electrolyte is particularly damaged, and the hydrophobicity of the catalyst layer is lost as a result. When the hydrophobicity of the catalyst layer on the surface of the gas diffusion electrode is also lost, the boundary between the electrolyte and the catalyst layer of the gas diffusion electrode becomes weak, allowing calcium ions in seawater to permeate the catalyst layer of the gas diffusion electrode, and this leads to the formation of calcium carbonate directly on the electrode surface, which is believed to induce the formation of deposits on the electrode surface.

[0192] Fig. 16 is an XRD graph of a precipitate within the electrolyte of the reduction electrode reaction tank of Comparative Example 5. Referring to Fig. 16, Comparative Example 5 appears to produce a precipitate mainly composed of calcium carbonate within the electrolyte of the reduction electrode reaction tank using seawater, similar to Example 5, regardless of damage to the gas diffusion electrode. This indicates that mineral carbonation occurs within the electrolyte of the reduction electrode in Comparative Example 5 regardless of damage to the gas diffusion electrode.

[0193] Table 4 shows the XRD analysis results of the precipitates in the reduction electrode reactor in Comparative Example 5 and Comparative Example 3. Referring to Table 4, in Comparative Example 3, most of the precipitates contain magnesium ions, whereas in Comparative Example 5, most of the precipitates contain calcium ions, and the main form of the precipitates appears to be calcium carbonate series.

[0194] Comparative Example 5 (Seawater electrolyte, damaged electrode, carbon dioxide supply) Name of precipitate compound Chemical formula of precipitate compound Weight ratio (%) Calcite monohydrate CaCO3 H2O 5 9.2 Calcite CaCO3 2 8.9 Calcium carbide CaC 2 5.6 Magnesium oxide MgO 2 6.4 Comparative Example 3 (Seawater electrolyte, normal electrode, carbon dioxide not supplied) Name of precipitate compound Chemical formula of precipitate compound Weight ratio (%) Brucite Mg(OH) 2 90 Calcite Magnesian Mg 0.1 Ca 0.9 CO34.1 AragoniteCaCO36

[0195] Fig. 17a is a graph comparing the change in the concentration of calcium ions in the reduction electrode reaction tank after electrolysis in Comparative Examples 3 and 5, and Fig. 17b is a graph comparing the change in the concentration of magnesium ions in the reduction electrode reaction tank after electrolysis in Comparative Examples 3 and 5. In Figs. 17a and 17b, C / C0 is the ratio of the concentration of the ion after electrolysis to the concentration before electrolysis. Referring to Figs. 17a and 17b, in Comparative Example 5, where the former reduction reaction (hydrogen peroxide production reaction) and carbon dioxide capture occurred simultaneously, it was found that the ability to remove calcium ions in the seawater electrolyte was maintained regardless of the damage to the gas diffusion electrode, and in the case of magnesium ions, the current density was 10.0 mA / cm 2 Under these conditions, only about 10% of the initial concentration was reduced. This is thought to be because in an environment where carbon dioxide is supplied, i.e., where carbonate ions are present, the reaction between carbonate ions and calcium ions is relatively favored. On the other hand, in Comparative Example 3, where only the electron reduction reaction (hydrogen peroxide production reaction) occurred, the current density was 10.0 mA / cm 2 Under these conditions, only about 10% of the initial calcium concentration was reduced, while about 40% of the initial magnesium concentration was removed. This is thought to be because Mg(OH)2 precipitate is formed by electrolysis in an environment without carbonate ions.

[0196] (8) Reaction in the oxidation electrode reactor

[0197] Fig. 18 is a graph showing the change in the concentration of chloride ions in the reduction electrode reaction tank and the oxidation electrode reaction tank after electrolysis in Comparative Example 5, analyzed by ion chromatography. In Fig. 18, C / C0 is the ratio of the concentration of chloride ions after electrolysis to the concentration before electrolysis. Referring to Fig. 18, as the current density increases, the concentration of chloride ions in the oxidation electrode reaction tank increases after electrolysis, and the concentration of chloride ions in the reduction electrode reaction tank decreases. This is thought to be because, when the chloride ions in the seawater electrolyte of the oxidation electrode reaction tank are oxidized to chlorine gas at the oxidation electrode, the chloride ions in the seawater electrolyte of the reduction electrode reaction tank diffuse into the oxidation electrode reaction tank through the anion exchange membrane. In other words, it is thought that the concentration of chloride ions in the reduction electrode reaction tank decreases and the concentration of chloride ions in the oxidation electrode reaction tank increases due to the diffusion of chloride ions in the reduction electrode reaction tank to the oxidation electrode reaction tank. While conventional electrolysis systems utilize a simple water decomposition reaction at the oxidation electrode as a counter-reaction to the hydrogen peroxide production reaction at the reduction electrode, this embodiment demonstrates that the oxidation reaction of chloride ions present in seawater can be utilized. Therefore, the electrolysis system according to the present invention demonstrates that chloride ions in seawater can be utilized to produce useful resources such as chlorine gas.

[0198] (9) Measurement of the weight of mineral carbonation products

[0199] Figure 19 is a graph measuring the weight of mineral carbonation products (sediment) obtained according to the electrolysis time in Comparative Example 5. Referring to the graph of Figure 19, at a current density of 10 mA / cm 2As the electrolysis time increases under these conditions, the weight of the resulting mineral carbonation product increases. Furthermore, the weight of the mineral carbonation product increases nonlinearly with time. This is believed to be because as the electrolysis time increases, the alkaline environment within the reduction electrode reactor becomes more intense, facilitating mineral carbonation.

[0200] The above examples demonstrate that the present invention possesses the ability to simultaneously capture hydrogen peroxide production and accelerated carbon dioxide, mineral carbonation utilizing calcium ions in seawater without separate energy consumption, and chlorine production capability in the oxidation electrode reactor. Furthermore, the present invention significantly increases the stability of the electrolysis system by suppressing the formation of electrode surface deposits, enhances the system's electrochemical hydrogen peroxide production capacity, and further reduces energy consumption.

[0201] While the present invention has been described with reference to the above-described embodiments, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. A reduction electrode reaction tank including a reduction electrode; An oxidation electrode reactor including an oxidation electrode; A separation membrane selectively permeating charge and ion species between the reduction electrode reaction tank and the oxidation electrode reaction tank; An oxygen supply unit that supplies oxygen to the above reduction electrode; and A carbon dioxide supply unit for supplying carbon dioxide to the above reduction electrode; An electrolysis device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the above reduction electrode is a gas diffusion electrode (GDE) including a hydrophobic carbon catalyst layer.

2. In paragraph 1, The above gas diffusion electrode is an electrolytic device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, formed by compressing a plurality of overlapping nickel foams.

3. In paragraph 1, An electrolytic device for simultaneous production of hydrogen peroxide and capture of carbon dioxide, wherein the carbon catalyst layer is a coating layer containing carbon on the surface of the gas diffusion electrode.

4. In paragraph 3, An electrolysis device for simultaneous production of hydrogen peroxide and capture of carbon dioxide, wherein the carbon catalyst layer comprises a hydrophobic binder.

5. In paragraph 1, An electrolysis device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the above separation membrane is an anion exchange membrane or a cation exchange membrane.

6. In paragraph 1, An electrolysis device for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the above reduction electrode reaction tank and the above oxidation electrode reaction tank each receive seawater, seawater concentrate, or bittern as an electrolyte.

7. A reduction electrode reaction tank including a reduction electrode; An oxidation electrode reactor including an oxidation electrode; A separation membrane selectively permeating charge and ion species between the reduction electrode reaction tank and the oxidation electrode reaction tank; An oxygen supply unit that supplies oxygen to the above reduction electrode; and A carbon dioxide supply unit for supplying carbon dioxide to the above reduction electrode; A step of providing an electrolysis device in which the above reduction electrode is a gas diffusion electrode including a hydrophobic carbon catalyst layer; A step of accommodating an electrolyte in the reduction electrode reaction tank and the oxidation electrode reaction tank; A step of supplying oxygen and carbon dioxide to the reduction electrode through the oxygen supply unit and the carbon dioxide supply unit; and An electrolysis method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, comprising a step of performing electrolysis by applying current or voltage to the reduction electrode and the oxidation electrode.

8. In paragraph 7, The above gas diffusion electrode is an electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein a plurality of overlapping nickel foams are compressed.

9. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the electrolyte comprises seawater, seawater concentrate or bittern.

10. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the carbon catalyst layer is a coating layer containing carbon on the surface of the gas diffusion electrode.

11. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the carbon catalyst layer comprises a hydrophobic binder.

12. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the above separation membrane is an anion exchange membrane or a cation exchange membrane.

13. In paragraph 7, An electrolysis method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the pH of the electrolyte in the portion in contact with the surface of the reduction electrode in the reduction electrode reaction tank is higher than the pH of the electrolyte in the middle portion of the reduction electrode reaction tank.

14. In paragraph 7, An electrolysis method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the pH of the electrolyte in the portion in contact with the surface of the reduction electrode in the reduction electrode reaction tank is 13 or higher.

15. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the pH of the electrolyte in the middle part of the reduction electrode reaction tank is in the range of 7.5 to 10.

16. In paragraph 7, The above carbon dioxide is bicarbonate ion (HCO3) in the electrolyte - ) or carbonate ions (CO3 2- ) An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, which is dissolved and captured in the form of hydrogen peroxide.

17. In paragraph 16, When the electrolyte contains calcium ions, the bicarbonate ions (HCO3) dissolved in the electrolyte - ) or carbonate ions (CO3 2- ) An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein at least a portion of the hydrogen peroxide reacts with the calcium ions to form calcium carbonate.

18. In paragraph 7, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the faradaic efficiency for producing hydrogen peroxide by the above electrolysis is 60% to 100%.

19. In paragraph 7, An electrolysis method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein the energy consumed to produce 1 kg of hydrogen peroxide in the electrolysis is 3 kWh to 30 kWh.

20. In paragraph 9, An electrolytic method for producing hydrogen peroxide and capturing carbon dioxide simultaneously, wherein hydrogen peroxide is produced at the reduction electrode, oxygen (O2) and chlorine (Cl2) are produced at the oxidation electrode, and mineral carbonate is produced within the reduction electrode reaction tank.

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