High-efficiency hydrogen production system by direct air capture method using renewable energy

Abstract

The present invention relates to a high-efficiency hydrogen production system by a direct air capture method using renewable energy. According to an embodiment of the present invention, the high-efficiency hydrogen production system comprises: a direct air capture device in which a chemical reaction occurs when an alkaline liquid mixture containing a specific component, such as potassium hydroxide or sodium hydroxide, is brought into contact with air, to capture carbon dioxide from the air; an electrolysis tank into which pure water and the sodium carbonate or potassium carbonate solution generated in the process of the chemical reaction for capturing carbon dioxide in the direct air capture device are introduced and then electrolyzed by using renewable energy including solar or wind power generation energy, to generate a gas containing hydrogen and a liquid containing potassium hydroxide or sodium hydroxide and separate and extract the generated gas and liquid; a gas storage tank in which the gas separated and extracted from the electrolysis tank is stored; and a liquid storage tank in which the remaining liquid after the gas is separated and extracted from the electrolysis tank is stored and potassium hydroxide or sodium hydroxide contained in the liquid is reintroduced into the direct air capture device.

Description

A high-efficiency hydrogen production system using direct air capture using renewable energy.

[0001] The present invention relates to a high-efficiency hydrogen production system using a direct air capture (DAC) method using renewable energy, and more specifically, to a high-efficiency hydrogen production system using a direct air capture method using renewable energy, which directly captures carbon dioxide in the atmosphere using renewable energy, converts the carbon dioxide, and electrolyzes a potassium carbonate or sodium carbonate solution obtained by converting the carbon dioxide to produce useful resources such as hydrogen, sodium hydroxide, potassium hydroxide, oxygen, or carbon dioxide, and the produced potassium hydroxide or sodium hydroxide is reused within the device, the produced carbon dioxide is reused for various purposes outside the device, and the green hydrogen produced in the process is used as a clean energy source, thereby having the advantages of being multi-purpose and environmentally friendly.

[0002] Recently, as climate change has emerged as a global issue, countries are actively responding, and major nations are introducing various policies to reduce greenhouse gases. With the Kyoto Protocol officially in effect, Korea is also in a position where it cannot avoid its obligation to reduce greenhouse gases. However, it is not enough to reverse the rising trend of greenhouse gas emissions.

[0003] Efforts to reduce carbon dioxide, a major component of these greenhouse gases, are being carried out in two main ways: one is to reduce carbon dioxide emitted into the air from carbon dioxide emission sources, and the other is to remove carbon dioxide already emitted into the air.

[0004] The second of these, a technology for removing carbon dioxide already emitted into the air, is commonly referred to as direct air capture (DAC).

[0005] More specifically, this technology reduces the concentration of carbon dioxide, a representative greenhouse gas, by capturing carbon dioxide in the air using various adsorption methods, such as chemical adsorption using various media such as alkaline solutions and physical adsorption using various catalysts.

[0006] The next thing to consider is that efforts to reduce carbon dioxide in the air can be divided into direct methods, such as suppressing carbon dioxide emissions or removing carbon dioxide from the air at the source, as explained above, and indirect methods, such as replacing carbon dioxide-emitting energy sources with energy sources that do not emit carbon dioxide at all.

[0007] Among the above-mentioned indirect methods, the energy source that has recently gained the most attention is green hydrogen. Green hydrogen refers to clean hydrogen obtained by decomposing water using renewable energy that does not emit carbon dioxide. Furthermore, the technology for decomposing water is also called water electrolysis.

[0008] However, in order to put into practice direct and indirect methods for reducing carbon dioxide as described above, it is necessary to consider factors such as economic feasibility, environmental friendliness, and structural feasibility.

[0009] First, economic issues include device reliability and durability, the production of single value-added substances, and limitations in reducing energy consumption associated with water decomposition. Environmental concerns include issues related to the extensive use of water, the use of pure water, and the use of alkaline solutions. Finally, structural issues include electrode arrangement and flow path formation in the standard cell configuration of the stack, among the electrolytic cell components.

[0010] Meanwhile, water electrolysis technology for producing green hydrogen is generally divided into the following four methods: alkaline method, polymer electrolyte membrane (PEM) method, anion exchange membrane (AEM) method, and solid oxide electrolysis cell (SOECs) method.

[0011] However, despite the various characteristics, advantages, and disadvantages of the above-mentioned methods, they are all experiencing difficulties in practical application as they are unable to overcome the problem of economic feasibility, with the production cost of hydrogen reaching 12,000 won / kg.

[0012] The fundamental technical problem of this is that a large amount of energy of 1.23 V is input to the decomposition of pure water supplied to both the anode and cathode of the electrolytic cell, as shown in the equation below.

[0013] - Bipolar reaction: H2O → 1 / 2O2+ 2H+ + 2e- (Standard potential: 0.40 V)

[0014] - Cathode reaction: 2H2O + 2e- → H2+ 2OH- (Standard potential: -0.83 V)

[0015] Therefore, as a way to solve the economic problem mentioned above while reducing carbon dioxide emissions at the same time, DAC (Direct Air Capture) electrolysis technology, which directly captures carbon dioxide from the air and ultimately produces green hydrogen using the captured carbon dioxide, is rapidly emerging as an alternative.

[0016] The present invention was created to solve the above-described problems, and the purpose of the present invention is to provide a high-efficiency hydrogen production system using a direct air capture method using renewable energy, which directly captures carbon dioxide in the atmosphere using renewable energy, converts the carbon dioxide, and electrolyzes a potassium carbonate or sodium carbonate solution obtained by converting the carbon dioxide to produce useful resources such as hydrogen, sodium hydroxide, potassium hydroxide, oxygen, or carbon dioxide, and the produced potassium hydroxide or sodium hydroxide is reused within the device, the produced carbon dioxide is reused for various purposes outside the device, and the green hydrogen produced in the process is used as a clean energy source, thereby having the advantages of being multi-purpose and environmentally friendly.

[0017] The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0018] In order to achieve the above object, a high-efficiency hydrogen production system using a direct air capture method using renewable energy according to one embodiment of the present invention comprises: a direct air capture device that captures carbon dioxide in the air by causing a chemical reaction by bringing a basic alkaline mixture of a specific component including potassium hydroxide or sodium hydroxide into contact with air; an electrolytic cell that generates a gas including hydrogen and a liquid including potassium hydroxide or sodium hydroxide by electrolysis using renewable energy including solar or wind power generation energy after injecting a sodium carbonate or potassium carbonate solution and pure water generated in the chemical reaction process of capturing carbon dioxide in the direct air capture device, and then separates and extracts the generated gas and liquid; a gas storage tank that stores the gas separated and extracted in the electrolytic cell; and a liquid storage tank that stores the remaining liquid after the gas is separated and extracted in the electrolytic cell, and reintroduces the potassium hydroxide or sodium hydroxide in the liquid into the direct air capture device.

[0019] In addition, according to one embodiment, the direct air capture device and the electrolytic cell further include a first transfer pump for transferring a potassium carbonate or sodium carbonate solution generated in the direct air capture device to the electrolytic cell; a pure water storage tank for storing pure water; a second transfer pump for transferring the pure water stored in the pure water storage tank to the electrolytic cell; and a third transfer pump for transferring and reintroducing the liquid stored in the liquid storage tank to the direct air capture device.

[0020] In addition, according to one embodiment, the electrolytic cell further includes a first gas-liquid separation device for separating and extracting carbon dioxide or oxygen from a product generated during the electrolytic treatment process of the electrolytic cell; and a second gas-liquid separation device for separating and extracting hydrogen from a product generated during the electrolytic treatment process of the electrolytic cell.

[0021] In addition, according to one embodiment, the gas storage tank includes a first gas storage tank for storing carbon dioxide or oxygen separated and extracted from a first gas-liquid separator; and a second gas storage tank for storing hydrogen separated and extracted from a second gas-liquid separator.

[0022] Also, according to one embodiment, the electrolytic cell comprises: an inlet end plate having an inlet for a potassium carbonate or sodium carbonate solution and an inlet for pure water; a positive current collector to which positive power is supplied from a rectifier; a positive metal electrode to which a foam-type positive electrode is bonded; a spacer for forming a flow path for the solution; a cation exchange membrane for moving potassium or sodium ions from the positive metal electrode to the negative metal electrode; positive and negative electrode supports for fixing the positive metal electrode, the spacer, and the cation exchange membrane, and separately maintaining an outflow path for a fluid including carbon dioxide, oxygen, and residual potassium carbonate or sodium carbonate solution from an inflow path for the potassium carbonate or sodium carbonate solution, and separately maintaining an outflow path for a fluid including hydrogen, potassium hydroxide or sodium hydroxide solution; a negative metal electrode to which a foam-type negative electrode is bonded; a negative current collector to which negative power is supplied from a rectifier; and an outlet end plate having separate outlets for a fluid including carbon dioxide, oxygen, residual potassium carbonate or sodium carbonate solution and outlets for a fluid including hydrogen, potassium hydroxide or sodium hydroxide solution;

[0023] Additionally, according to one embodiment, the spacer is characterized in that it is formed of one or more materials selected from polyethylene, polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, and polycarbonate.

[0024] In addition, according to one embodiment, the positive metal electrode or the negative metal electrode is characterized in that it is formed of at least one material selected from among stainless steel metal alloy, Bi, Ni, Cd, Co, Ti, Fe, Mn, Mo, Al, Zn, Au, In, Ga, and W.

[0025] In addition, according to one embodiment, the electrolytic cell is characterized by being a serial multilayer electrolytic cell in which an inlet end plate and an outlet end plate are arranged at each end, and a plurality of cells including a positive collector and a negative collector are connected in multiple layers between the inlet end plate and the outlet end plate, and power is connected in series only to the positive collector and the negative collector at each end.

[0026] In addition, according to one embodiment, the electrolytic cell is characterized by being a parallel multilayer electrolytic cell in which an inlet end plate and an outlet end plate are arranged at each end, and a plurality of cells including a positive collector and a negative collector are connected in multiple layers between the inlet end plate and the outlet end plate, and a power source is connected in parallel to each of the positive collector and the negative collector.

[0027] Additionally, according to one embodiment, an insulator is further provided between the positive and negative collectors at the middle portion, excluding the positive and negative collectors at the two ends.

[0028] Embodiments of the disclosed technology may have the following advantages. However, this does not mean that embodiments of the disclosed technology must include all of these, and therefore the scope of the disclosed technology should not be construed as being limited thereby.

[0029] According to one embodiment of the present invention, by directly capturing carbon dioxide in the atmosphere, it is possible to remove carbon dioxide in the atmosphere and produce high-purity green hydrogen, and to produce carbon resources such as sodium carbonate or sodium bicarbonate, which are other useful substances, by using the removed carbon dioxide.

[0030] In addition, according to one embodiment of the present invention, by utilizing carbon dioxide reactants such as sodium carbonate or sodium bicarbonate converted into carbon resources as an electrolyte, more green hydrogen can be produced compared to conventional general water electrolysis technology, and furthermore, oxygen, a useful resource, can be produced during the electrolysis process.

[0031] Figure 1 is a conceptual diagram of a high-efficiency hydrogen production system using a direct air capture method using renewable energy of the present invention.

[0032] Figure 2 is a block diagram showing the operation process of a hydrogen production system according to one embodiment of the present invention.

[0033] Figure 3 is a drawing showing the pre-assembly components of a single-layer electrolytic cell according to the first embodiment of the present invention.

[0034] Fig. 4 is a side view showing the single-layer electrolytic cell of Fig. 3 in an assembled state.

[0035] Figure 5 is a side view showing a serial multilayer electrolytic cell according to the second embodiment of the present invention.

[0036] Figure 6 is a side view showing a parallel multilayer electrolytic cell according to the third embodiment of the present invention.

[0037] Figure 7 shows the pH change before and after the reaction according to the concentration of potassium carbonate according to the present invention.

[0038] The present invention can have various modifications and various embodiments, and specific embodiments are illustrated in the drawings and specifically described in the detailed description.

[0039] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0040] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0041] Hereinafter, a high-efficiency hydrogen production system using a direct air capture method using renewable energy according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0042] Figure 1 is a conceptual diagram of a high-efficiency hydrogen production system using a direct air capture method using renewable energy of the present invention.

[0043] Referring to FIG. 1, the hydrogen production system of the present invention may be configured to include an electrolytic cell (200) that is connected to a direct air capture device (100) that captures carbon dioxide in the air and decomposes a potassium carbonate or sodium carbonate solution produced in the direct air capture device (100), a first gas-liquid separator (300) that separates carbon dioxide and oxygen gas produced in the anode body (244, 246, 248, 250, see FIG. 3) of the electrolytic cell (200) and the remaining potassium carbonate or sodium carbonate solution into gas and liquid, and a second gas-liquid separator (400) that separates hydrogen gas produced in the cathode body (254, 255, 256, see FIG. 3) of the electrolytic cell (200) and a potassium hydroxide or sodium hydroxide solution into gas and liquid.

[0044] According to one embodiment, the direct air collection device (100) may be implemented in the form of a 'cascade-type artificial forest creation device' (Patent Registration No. 2499516, registered on February 9, 2023) for which the applicant of the present invention previously secured patent rights, and although not directly included in the spirit of the present invention to help understanding of the present invention, according to one embodiment, it has the following configuration.

[0045] The above-mentioned 'cascade-type artificial forest creation device', that is, the direct air collection device (100) according to the present invention, as mentioned in its specification, comprises: a cascade flow path assembly having a plurality of partitions horizontally stacked in multiple stages at regular intervals inside a rectangular casing, and the left and right ends of the partitions communicating with each other in a staggered manner, thereby forming a zigzag-shaped internal flow path; an air intake unit connected to one side of the lower portion of the cascade flow path assembly to suck in ambient air and induce the sucked air to flow upward along the internal flow path of the cascade flow path assembly; a mixture storage unit provided at the lower portion of the cascade flow path assembly, which stores a basic alkaline mixture of a specific component that captures carbon dioxide in the air by causing a chemical reaction upon contact with air, and when air is sucked in through the air intake unit, supplies the basic alkaline mixture to the upper portion of the cascade flow path assembly, and induces the basic alkaline mixture to come into surface contact with the air while flowing downward by its own weight along the internal flow path of the cascade flow path assembly; And it includes an air exhaust unit provided on the upper part of the cascade euro assembly and discharging the remaining air from which carbon dioxide has been removed while passing through the internal euro to the surroundings.

[0046] In addition, the reason why it is a prerequisite to be connected to the above direct air collection device (100) is that the substance produced when the KOH (potassium hydroxide) or NaOH (sodium hydroxide) solution used as the basic alkaline mixture reacts with carbon dioxide in the air is Na2CO3 (sodium carbonate) or K2CO3 (potassium carbonate), as shown in <Reaction Formula 1> below, and there is a problem that the KOH or NaOH solution is continuously injected during this process.

[0047] <Reaction Scheme 1>

[0048] 2KOH + CO2→ K2CO3+ H2O

[0049] 2NaOH + CO2→ Na2CO3+ H2O

[0050] Therefore, in order to minimize the new input of KOH or NaOH solution used in the direct air collection device (100), as shown in <Reaction Schemes 2 and 3> below, it is significant to produce KOH (see Reaction Scheme 2) or NaOH (see Reaction Scheme 3) solution in the electrolytic cell (200) according to the present invention and reuse (re-inject) it into the direct air collection device (100).

[0051] <Reaction Formula 2>

[0052] Bipolar reaction: 2K2CO3+ H2O → 2CO2+ O2+ 4K+ + 4e- + H2O

[0053] Cathode reaction: 4K+ + 4H2O → 2H2+ 4KOH

[0054] <Reaction Formula 3>

[0055] Bipolar reaction: 2Na2CO3+ H2O → 2CO2+ O2+ 4Na+ + 4e- + H2O

[0056] Cathode reaction: 4Na+ + 4H2O → 2H2+ 4NaOH

[0057] At this time, since additional energy, which is electricity produced from renewable energy, must be input into the electrolytic cell (200) during the operation of the electrolytic cell (200), it is difficult to meet economic feasibility by simply producing a KOH or NaOH solution and reusing it in the direct air collection device (100). Therefore, considering this point, the present invention can obtain an additional advantage of being able to utilize hydrogen produced simultaneously in the production process of the KOH or NaOH solution in the above <Reaction Formulas 2 and 3> as green hydrogen.

[0058] In addition, since carbon dioxide is generated during the operation of the electrolytic cell (200), this runs counter to the original purpose of reducing carbon dioxide in the air. The carbon dioxide produced at this time can be permanently sequestered again by various methods, and since the method for permanently sequestering the carbon dioxide is not included in the scope of the present invention, a detailed description thereof will be omitted.

[0059] Figure 2 is a block diagram showing the operation process of an electrolysis system according to one embodiment of the present invention.

[0060] Referring to the above drawing 2, the overall operation process of the electrolysis system of the present invention will be examined according to one embodiment as follows.

[0061] First, a sodium carbonate (Na2CO3) or potassium carbonate (K2CO3) solution is introduced from a direct air collection device (100) into the anode of the electrolytic cell (200) at a flow rate of 1 ml / min per unit electrode area using a first transfer pump (720), and at the same time, pure water is introduced from a pure water storage tank (600) into the cathode of the electrolytic cell (200) at a flow rate of 0.2 L / h per 15.2 cm2 using a second transfer pump (740).

[0062] At this time, when the value of the pH meter (220) installed in the outlet line of the first transfer pump (720) indicates a value less than 12.5, the solution is introduced into the electrolytic cell (200), and when it is 12.5 or higher, the potassium carbonate or sodium carbonate solution is circulated to the direct air collection device (100).

[0063] Next, the potassium carbonate or sodium carbonate solution is continuously introduced for 20 to 60 minutes to uniformly wet the internal cell components of the electrolytic cell, such as the cation exchange membrane, electrode, and spacer, with the potassium carbonate or sodium carbonate solution.

[0064] After each of the above potassium carbonate or sodium carbonate solutions is introduced into each electrode body (anode body, cathode body) for 20 to 60 minutes, while continuing to introduce the solution, a voltage of 1.5 to 4.0 V is applied to the electrolytic cell (200) from the rectifier (800). At this time, the rectifier (800) is initially in constant pressure mode, but when the output current exceeds 4.0 A, in order to prevent deterioration of the electrodes and cation membrane of the electrolytic cell (200), it is switched from constant voltage mode to constant current mode, and the applied voltage is automatically adjusted so as not to exceed 4 V.

[0065] Continuing, as soon as voltage is applied through the rectifier (800), gas bubbles generated at the anode and cathode outlet lines of the stack are checked, and if no gas bubbles are visible, the power is immediately turned off, the cause is identified, and normal measures are taken. Meanwhile, if gas bubbles are confirmed, the first gas-liquid separator (510) separates gases such as carbon dioxide and oxygen and liquids such as residual potassium carbonate or sodium carbonate solution, and the second gas-liquid separator (520) separates hydrogen gas and liquids such as potassium hydroxide or sodium hydroxide solution.

[0066] In addition, gases such as carbon dioxide and oxygen separated in the first gas-liquid separation device (510) are stored in the first gas storage tank (300), and hydrogen gas separated in the second gas-liquid separation device (520) is stored in the second gas storage tank (400). Meanwhile, when the solutions (sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, etc.) separated in the first gas-liquid separation device (510) and the second gas-liquid separation device (520) reach 2 / 3 of the height of the separation devices (510, 520), they are transferred to the liquid storage tank (760) by gravity through valves mounted at the bottoms of the first gas-liquid separation device (510) and the second gas-liquid separation device (520).

[0067] Afterwards, when the liquid storage tank (760) is filled with the solution, the third transfer pump (770) is operated to transfer the solution to the direct air collection device (100) and finally reintroduce it.

[0068] Figure 3 is a drawing showing the pre-assembly components of a single-layer electrolytic cell according to the first embodiment of the present invention.

[0069] Referring to the above Figure 3, the detailed configuration of the electrolytic cell (200) includes: an inlet end plate (242) having a potassium carbonate or sodium carbonate solution inlet (260) and a pure water inlet (262); a positive current collector (244) to which positive (+) power is supplied from a rectifier (800); a positive metal electrode (246) to which a foam-type positive electrode is joined; a spacer (248) for forming a flow path for the solution; a cation exchange membrane (250) for moving only potassium ions or sodium ions from the positive metal electrode (246) to the negative electrode (255); The positive and negative electrode support (252) which fixes the positive metal electrode (246), spacer (248) and cation exchange membrane (250), and maintains the inflow passage of potassium carbonate or sodium carbonate solution and the outflow passage of carbon dioxide, oxygen and residual potassium carbonate or sodium carbonate solution separately, and maintains the outflow passage of hydrogen and potassium hydroxide or sodium hydroxide solution separately, thereby separating the flow paths of the anode and cathode bodies respectively, and preventing the inflow passage of potassium carbonate or sodium carbonate solution and the outflow passage of carbon dioxide, oxygen and residual potassium carbonate or sodium carbonate solution and the inflow passage of pure water and the outflow passage of hydrogen and potassium hydroxide or sodium hydroxide solution from mixing with each other; a foam-type negative electrode (254); a negative metal electrode (255) to which the foam-type negative electrode is joined, a negative current collector (256) to which negative (-) power is supplied from a rectifier (800); and an outlet end plate (258) having an outlet (266) for carbon dioxide and oxygen and residual potassium carbonate or sodium carbonate solution and an outlet (264) for hydrogen and potassium hydroxide or sodium hydroxide solution.

[0070] At this time, the spacer (248) may be formed of one or more materials selected from among polyethylene, polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, and polycarbonate, according to one embodiment.

[0071] In addition, the positive metal electrode (246) or the negative metal electrode (255) may be formed of at least one material selected from among stainless steel metal alloy, Bi, Ni, Cd, Co, Ti, Fe, Mn, Mo, Al, Zn, Au, In, Ga, and W.

[0072] Figure 4 is a side view showing the single-layer electrolytic cell of Figure 3 in an assembled state.

[0073] Referring to the above drawing 4, the configuration and flow path of the electrolytic cell (200) in an assembled state are examined according to one embodiment in terms of the external appearance. The potassium carbonate (or sodium carbonate) solution is introduced through the potassium carbonate or sodium carbonate solution inlet (260) of the inlet end plate (242) having the potassium carbonate or sodium carbonate solution inlet (260) and the pure water inlet (262), and the potassium carbonate solution flows horizontally through the positive current collector (244) to which positive (+) power is supplied from the rectifier (800), the positive metal electrode (246) to which the foam electrode is joined, the spacer (248) for forming the flow path of the solution, and the like, thereby producing carbon dioxide and oxygen, and the remaining potassium carbonate solution is introduced through the outlet (266) of the outlet end plate (258).

[0074] Meanwhile, pure water is introduced through the inlet (262) of the inlet end plate (242), flows horizontally through the foam-type negative electrode (254), the negative metal electrode (255) to which the foam-type negative electrode is joined, and the negative collector (256) supplied with negative power from the rectifier (800), whereby water is decomposed to produce hydrogen, and flows out through the outlet (264) of the outlet end plate (258) together with potassium hydroxide generated by reacting with potassium ions moving vertically through the cation membrane from the positive electrode body.

[0075] In addition, according to one embodiment, the electrolytic cell may further be provided with a sensing unit (not shown) that detects information of the solution, including electrical conductivity, pH, temperature, etc. of the solution (potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate solution); and a control unit (not shown) that controls the electrolytic device based on information of the sensing unit.

[0076] The control unit controls the magnitude of the voltage applied from the rectifier (800) to the anode and cathode of the electrolytic cell (200) and the flow rate of the solution flowing into the electrolytic cell (200) based on the characteristics of the solution detected by the sensing unit. That is, the control unit can perform a control function of decreasing or increasing the voltage depending on the values ​​of electrical conductivity, pH, temperature, etc. detected by the sensing unit.

[0077] Meanwhile, the electrolytic cell (200) can be configured by increasing the number of electrolytic cells (200) according to the required processing amount, and after increasing the number of electrolytic cells (200), the electrolytic cells can be configured as a serial multilayer electrolytic cell (200-A) or a parallel multilayer electrolytic cell (200-B) by connecting them in multiple layers according to the purpose.

[0078] FIG. 5 is a side view showing a serial multilayer electrolytic cell (200A) according to a second embodiment of the present invention.

[0079] Referring to the above drawing 5, the configuration of the serial multilayer electrolytic cell (200A) supplies power only to the positive collector (244) and negative collector (256) at both ends of the electrolytic cell (200A), and the internal cells are connected in series.

[0080] That is, the above-described serial multilayer electrolytic cell (200A) has an inlet end plate (242) and an outlet end plate (258) arranged at each end, and a plurality of cells (cells, 244 to 256) including a pair of positive collectors (244) and negative collectors (256) are connected in multiple layers between the inlet end plate (242) and the outlet end plate (258). At this time, power is connected in series from the rectifier only to the positive collectors (244) and negative collectors (256) at each end.

[0081] Figure 6 is a side view showing a parallel multilayer electrolytic cell (200B) according to a third embodiment of the present invention.

[0082] Referring to the above drawing 6, the configuration of the parallel multilayer electrolytic cell (200B) applies voltage to all electrodes within the electrolytic cell (200B), and at this time, all positive (+) potentials are connected to the anodes (244, 246, 248, 250) of the parallel multilayer electrolytic cell (200B), and all negative (-) potentials are connected to the cathodes (254, 255, 256).

[0083] That is, the parallel multilayer electrolytic cell (200B) has an inlet end plate (242) and an outlet end plate (258) arranged at each end, and a plurality of cells (244 to 256) including a pair of positive collectors (244) and negative collectors (256) are connected in multiple layers between the inlet end plate (242) and the outlet end plate (258). At this time, power is connected in parallel from a rectifier (800) to not only the positive collectors (244) and negative collectors (256) at both ends, but also the positive collectors (244) and negative collectors (256) at the middle.

[0084] In addition, in this case, it is preferable to place an insulator (268) for insulation between all positive and negative collectors (244) and negative collectors (256) at the ends of the electrolytic cell (200B) except for the positive and negative collectors (244) and negative collectors (256) at both ends of the electrolytic cell (200B).

[0085] Experimental Example: pH Measurement Experiment

[0086] Figure 7 is a pH change diagram before and after the reaction according to the concentration of potassium carbonate according to the present invention.

[0087] Referring to the above Figure 7, in order to confirm whether the above reaction occurred in the electrolytic cell (200) as an embodiment of the present invention, the pH before introduction into the electrolytic cell (200) and the pH change in the solution passing through the anode (244, 246, 248, 250) and the solution passing through the cathode (254, 255, 256) for potassium carbonate (K2CO3) solutions having concentrations of 20%, 30%, 40%, and 45%, respectively, were measured.

[0088] As shown in Fig. 7, the pH of the anode-passed solution decreased after the reaction for all concentrations of potassium carbonate solutions compared to before the reaction, which means that the potassium carbonate solution was decomposed and converted into carbon dioxide gas, thereby decreasing the concentration of potassium carbonate in the solution. In addition, the pH of the cathode-passed solution increased after the reaction for all concentrations of potassium carbonate solutions compared to before the reaction, which means that potassium hydroxide was produced in the cathode.

[0089] In addition, after manufacturing an electrolytic cell according to one embodiment of the present invention, 20%, 30%, 40%, and 45% of potassium carbonate solutions were introduced into the electrolytic cell (200), and the gas separated from the first gas-liquid separator (510) was analyzed for components, and as a result, both carbon dioxide and oxygen were detected. At this time, the concentration of the detected carbon dioxide was measured to be 19 to 30%, and the concentration of oxygen was measured to be 70 to 81%.

[0090] In addition, as a result of analyzing the components of the gas separated in the second gas-liquid separator (520) after introducing 20%, 30%, 40%, and 45% potassium carbonate solutions into the electrolytic cell (200), hydrogen was detected, and the concentration of the hydrogen detected at this time was measured to be 90 to 99%.

[0091] In addition, when 20%, 30%, 40%, and 45% of potassium carbonate solutions were introduced into the electrolytic cell (200), the instantaneous power at the point where the carbon dioxide concentration reached its peak value of 19 to 30% was 9.6 W, 12.8 W, 13.2 W, and 16 W, respectively.

[0092] Therefore, the flow rate, flow velocity, and current density derived from the experimental results described above are as shown in Table 1 below.

[0093] Flow rate (L / h, at 15.2 cm2)Flow velocity (m / min)Current density (A / m2)0.10 ~ 0.140.9 ~ 1.025 ~ 30

[0094] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential characteristics thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present specification is indicated by the scope of the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included within the scope of the present specification.

[0095] Meanwhile, this specification and drawings disclose preferred embodiments of this specification, and although specific terms are used, they are used in a general sense only to easily explain the technical contents of this specification and help understand the invention, and are not intended to limit the scope of this specification. It will be apparent to those skilled in the art that other modified examples based on the technical idea of ​​this specification are possible in addition to the embodiments disclosed herein.

[0096] The present invention can be widely used in the field of high-efficiency hydrogen production systems using direct air capture using renewable energy.

Claims

1. A direct air capture device that captures carbon dioxide in the air by causing a chemical reaction by bringing a basic alkaline mixture containing a specific component including potassium hydroxide or sodium hydroxide into contact with the air; An electrolytic cell that generates a gas containing hydrogen and a liquid containing potassium hydroxide or sodium hydroxide by electrolyzing a sodium carbonate or potassium carbonate solution and pure water generated in a chemical reaction process of capturing carbon dioxide in the above direct air capture device using renewable energy including solar or wind power generation energy, and then separates and extracts the generated gas and liquid; A gas storage tank for storing the gas separated and extracted from the electrolytic cell; and A high-efficiency hydrogen production system using a direct air capture method using renewable energy, including a liquid storage tank that stores the remaining liquid after the gas is separated and extracted in the electrolytic cell, and reintroduces potassium hydroxide or sodium hydroxide in the liquid into a direct air capture device.

2. In paragraph 1, Between the direct air capture device and the electrolytic cell, there is provided a first transfer pump for transferring the potassium carbonate or sodium carbonate solution generated in the direct air capture device to the electrolytic cell; Pure water storage tank for storing pure water; A second transfer pump for transferring the pure water stored in the pure water storage tank to the electrolysis tank; and A high-efficiency hydrogen production system using renewable energy by direct air capture, further comprising a third transfer pump that transfers and reintroduces liquid stored in a liquid storage tank to a direct air capture device.

3. In paragraph 1, In the above electrolytic cell, A first gas-liquid separation device for separating and extracting carbon dioxide or oxygen from the products generated during the electrolytic treatment process of the electrolytic cell; and A high-efficiency hydrogen production system using a direct air capture method using renewable energy, further comprising a second gas-liquid separation device for separating and extracting hydrogen from the products generated during the electrolytic treatment process of the electrolytic cell.

4. In paragraph 3, The above gas storage tank, A first gas storage tank for storing carbon dioxide or oxygen separated and extracted from the first gas-liquid separator; and A high-efficiency hydrogen production system using a direct air capture method using renewable energy, including a second gas storage tank for storing hydrogen separated and extracted from a second gas-liquid separation device.

5. In paragraph 1, The above electrolytic cell, An inlet end plate having an inlet for potassium carbonate or sodium carbonate solution and an inlet for pure water; A positive current collector supplied with positive (+) power from a rectifier; A bimetallic electrode with a foam-type positive electrode bonded thereto; Spacer for forming a flow path of the solution; A cation exchange membrane that moves potassium or sodium ions from the positive metal electrode to the negative metal electrode; A positive and negative electrode support that fixes the above-mentioned positive metal electrode, spacer and cation exchange membrane, and separately maintains an outlet passage for a fluid including carbon dioxide, oxygen, residual potassium carbonate or sodium carbonate solution from an inlet passage for potassium carbonate or sodium carbonate solution, and separately maintains an outlet passage for a fluid including hydrogen, potassium hydroxide or sodium hydroxide solution; A negative metal electrode to which a foam-type negative electrode is bonded; A negative power supply circuit supplied with negative (-) power from a rectifier; and A high-efficiency hydrogen production system using a direct air capture method using renewable energy, comprising an outlet end plate having separate outlets for a fluid containing carbon dioxide, oxygen, residual potassium carbonate or sodium carbonate solution, and outlets for a fluid containing hydrogen, potassium hydroxide or sodium hydroxide solution.

6. In paragraph 5, The above spacer, A high-efficiency hydrogen production system using a direct air capture method using renewable energy, characterized in that it is formed of one or more materials selected from among polyethylene, polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, and polycarbonate.

7. In paragraph 5, The above positive or negative metal electrode is, A high-efficiency hydrogen production system using a direct air capture method using renewable energy, characterized in that it is formed of at least one material selected from among stainless steel metal alloys, Bi, Ni, Cd, Co, Ti, Fe, Mn, Mo, Al, Zn, Au, In, Ga, and W.

8. In paragraph 5, The above electrolytic cell, A high-efficiency hydrogen production system using a direct air capture method using renewable energy, characterized by a series multilayer electrolyzer in which an inlet end plate and an outlet end plate are arranged at each end, a plurality of cells including a positive collector and a negative collector are connected in multiple layers between the inlet end plate and the outlet end plate, and power is connected in series only to the positive collector and negative collector at each end.

9. In paragraph 5, The above electrolytic cell, A high-efficiency hydrogen production system using a direct air capture method using renewable energy, characterized by a parallel multilayer electrolyzer in which an inlet end plate and an outlet end plate are arranged at each end, a plurality of cells including a positive collector and a negative collector are connected in multiple layers between the inlet end plate and the outlet end plate, and power is connected in parallel to each positive collector and negative collector.

10. In paragraph 9, A high-efficiency hydrogen production system using a direct air capture method using renewable energy, in which an insulator is additionally installed between the positive and negative collectors in the middle section, excluding the positive and negative collectors at both ends.

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