KR20230143516A - Water electrolysis system to produce calcium carbonate - Google Patents

Abstract

It is a water electrolysis system that produces hydrogen and calcium carbonate using carbon dioxide, and has the advantage of being able to produce not only oxygen and chlorine, but also hydrogen and calcium carbonate with high purity.

Description

Water electrolysis system to produce calcium carbonate}

This relates to a water electrolysis system that produces hydrogen and calcium carbonate using carbon dioxide.

Recently, with industrialization, greenhouse gas emissions are continuously increasing, and carbon dioxide accounts for the largest proportion of greenhouse gases. Carbon dioxide emissions by industry type are highest from energy sources such as power plants, and carbon dioxide generated from cement/steel/refining industries, including power generation, accounts for half of global emissions. The field of carbon dioxide conversion/utilization can be broadly divided into chemical conversion, biological conversion, and direct utilization, and technical categories include catalyst, electrochemistry, bioprocess, light utilization, inorganic (carbonation), and polymer. Carbon dioxide is generated from various industries and processes, and since carbon dioxide reduction cannot be achieved with one technology, various approaches are needed to reduce carbon dioxide.

Currently, the U.S. Department of Energy (DOE) is interested in CCUS technology, which is a combination of CCS (Carbon Capture Storage) and CCU (CC & Utilization), as a technology to reduce carbon dioxide and is pursuing multifaceted technology development. CCUS technology is recognized as an effective greenhouse gas reduction method, but it faces the problems of high investment costs, the possibility of releasing harmful collectors into the air, and low technology maturity. Additionally, from an energy and climate policy perspective, CCUS provides a means to substantially reduce greenhouse gas emissions, but there are many complements to the realization of the technology. Therefore, there is a need to develop a new sustainable breakthrough technology that captures, stores, and utilizes carbon dioxide more efficiently.

Meanwhile, the method of producing precipitated calcium carbonate (PCC) is largely produced by injecting carbon dioxide gas into a solution containing dissolved calcium and mixing a soluble carbonate solution with a dissolved calcium salt solution. There are ways to do it, etc.

However, when injecting carbon dioxide in gaseous form, carbon dioxide must be secured separately, and quality control is not easy. Additionally, some of the carbon dioxide that fails to react is released into the atmosphere during the reaction, and carbon dioxide is generated during the firing process, causing environmental pollution. Moreover, the manufacturing process is complicated, and the manufacturing cost increases by calcining limestone at a high temperature of 1000°C or higher to produce quicklime, an intermediate material.

Therefore, in order to reduce the amount of carbon dioxide generated and lower the cost of producing calcium carbonate, there is a problem that calcium components should not be supplied to limestone and a calcium source that does not bind to carbon dioxide should be used.

On the other hand, when liquid calcium carbonate is produced by mixing a dissolved calcium salt solution with a soluble carbonate solution, there is a problem of increased cost because additional carbonate, etc. must be secured.

Republic of Korea Patent Publication No. 10-1388217

The purpose of solving the above problem is as follows.

a cathode portion including a first aqueous solution contained in a first accommodating space, and a cathode (anode) at least partially submerged in the first aqueous solution; an anode portion including a second aqueous solution contained in a second accommodating space and a metal anode at least partially submerged in the second aqueous solution; a connecting portion including a connecting passage that communicates the first accommodating space and the second accommodating space, and an ion exchange membrane located in the connecting passage; A power supply device connecting the cathode and anode; And a calcium carbonate generator connected to the first accommodating space and the third accommodating space to generate calcium carbonate (CaCO _{3 (S)} ); When power is supplied to the power supply device, hydrogen gas and calcium carbonate are generated. The purpose is to provide a water electrolysis system that generates electricity.

A water electrolysis system according to one aspect includes a cathode portion including a first aqueous solution contained in a first accommodating space, and a cathode (anode) at least partially submerged in the first aqueous solution; an anode portion including a second aqueous solution contained in a second accommodating space, and a metal anode at least partially submerged in the second aqueous solution; A power supply device connecting the cathode and anode; a connecting portion including a connecting passage that communicates the first accommodating space and the second accommodating space, and an ion exchange membrane located in the connecting passage; And a calcium carbonate generator connected to the first accommodating space and the third accommodating space to generate calcium carbonate (CaCO _{3 (S)} ). When power is supplied to the power supply device, the first accommodating space is connected to the first accommodating space and the third accommodating space. Carbon dioxide gas flows into the electrolyte solution, and hydrogen ions (H ⁺ ) and bicarbonate ions (HCO ₃ ^- ) are generated by the reaction of the first electrolyte solution and the carbon dioxide gas, and the hydrogen ions (H ⁺ ) and the power supply supply It is characterized in that hydrogen gas (H ₂ ) is generated by combining electrons (e ^- ).

The calcium carbonate generating unit includes a reactor that generates calcium carbonate (CaCO _3(S) ); A first inlet connecting the first accommodation space and the reactor and introducing bicarbonate ions (HCO ₃ ^- ) from the first accommodation space into the reactor; A second inlet connected to the reactor and introducing calcium ions (Ca ²⁺ ) into the reactor; and a third inlet that connects the third accommodating space and the reactor and injects the remaining liquid after the calcium carbonate (CaCO _3(S) ) production reaction into the third accommodating space.

The anode may include an oxygen evolution reaction catalyst.

The oxygen evolution reaction catalyst may be one or more selected from the group consisting of metal oxide catalysts, perovskite oxide catalysts, metal sulfide catalysts, metal carbide catalysts, and carbon catalysts.

The metal contained in the oxygen evolution reaction catalyst is selected from the group consisting of Li, Co, Ni, Zn, Fe, Ti, Na, Mn, Cu, Ga, Sn, Cr, W, Ru, Ir, Pt, and Au. There may be at least one type.

The cathode may include carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, and metal thin film.

The cathode may further include a hydrogen evolution reaction catalyst.

The carbon dioxide treatment unit may further include a carbon dioxide treatment unit that communicates with the first accommodation space and includes a third aqueous solution accommodated in the third accommodation space.

The carbon dioxide treatment unit may separate unionized carbon dioxide gas from the carbon dioxide gas flowing into the third accommodation space from the third aqueous solution and prevent it from being supplied to the anode unit.

The carbon dioxide treatment unit may separate the non-ionized carbon dioxide gas using a difference in specific gravity from the third aqueous solution.

The carbon dioxide treatment unit is located below the water surface of the third aqueous solution in the third accommodation space and includes an inlet through which carbon dioxide gas flows. and a communication port located below the inlet and formed to communicate with the first accommodating space in the third accommodating space.

The cathode unit may further include a first outlet that is located above the water surface of the first aqueous solution accommodated in the first accommodation space and discharges hydrogen gas generated during discharge.

The carbon dioxide treatment unit may be located above the water surface of the third aqueous solution in the third accommodation space and may further include a second outlet through which the non-ionized carbon dioxide gas is discharged during discharge.

The carbon dioxide treatment unit may further include a carbon dioxide circulation supply unit that resupplies the non-ionized carbon dioxide gas to the third aqueous solution in the third accommodation space.

The first or second aqueous solution may be an alkaline aqueous solution containing alkaline metal ions.

Alkaline metal ions in the second accommodation space may move to the first accommodation space through the ion exchange membrane.

The water electrolysis system according to one aspect has the advantage of being able to produce not only oxygen and chlorine, but also hydrogen and calcium carbonate with high purity.

Figure 1 is a schematic diagram showing the water electrolysis process of a water electrolysis system according to an embodiment.
Figure 2 is a schematic diagram showing the water electrolysis process of a water electrolysis system according to another embodiment.

The above objects, other objects, features and advantages will be easily understood through the following preferred embodiments in conjunction with the accompanying drawings. However, it is not limited to the embodiments described here and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content will be thorough and complete and the technical ideas can be sufficiently conveyed to those skilled in the art.

While describing each drawing, similar reference numerals are used for similar components. In the attached drawings, the dimensions of the structures are enlarged from the actual size for clarity of the present invention. Terms such as first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof. Additionally, when a part of a layer, membrane, region, plate, etc. is said to be “on” another part, this includes not only being “directly above” the other part, but also cases where there is another part in between. Conversely, when a part of a layer, membrane, region, plate, etc. is said to be "underneath" another part, this includes not only being "immediately below" the other part, but also cases where there is another part in between.

Unless otherwise specified, all numbers, values, and/or expressions used herein expressing quantities of components, reaction conditions, polymer compositions, and formulations are intended to represent, among other things, how such numbers inherently occur in obtaining such values. Since they are approximations reflecting the various uncertainties of measurement, they should be understood in all cases as being qualified by the term "approximately". Additionally, where a numerical range is disclosed herein, such range is continuous and, unless otherwise indicated, includes all values from the minimum to the maximum of such range inclusively. Furthermore, when such range refers to an integer, all integers from the minimum value up to and including the maximum value are included, unless otherwise indicated.

In this specification, when a range is stated for a variable, the variable will be understood to include all values within the stated range, including the stated endpoints of the range. For example, the range "5 to 10" includes the values 5, 6, 7, 8, 9, and 10, as well as any subranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc. It will be understood that it also includes any values between integers that fall within the scope of the stated range, such as 5.5, 6.5, 7.5, 5.5 to 8.5, and 6.5 to 9, etc. Also, for example, the range "10% to 30%" includes values such as 10%, 11%, 12%, 13%, etc. and all integers up to and including 30%, as well as 10% to 15%, 12% to 12%, etc. It will be understood that it includes any subranges, such as 18%, 20% to 30%, etc., and any value between reasonable integers within the range of the stated range, such as 10.5%, 15.5%, 25.5%, etc.

Although many means have been provided to reduce conventional greenhouse gas emissions, there is a need to develop a new concept of sustainable breakthrough technology that captures, stores, and utilizes carbon dioxide more efficiently. In addition, in order to reduce carbon dioxide emissions and lower the cost of producing calcium carbonate, there was a problem that calcium components should not be supplied to limestone and a calcium source that does not bind to carbon dioxide should be used.

Accordingly, the present inventors conducted intensive research to solve the above problem, and as a result, a cathode portion including a first aqueous solution included in the first accommodation space and a cathode (anode) at least partially submerged in the first aqueous solution; an anode portion including a second aqueous solution contained in a second accommodating space and a metal anode at least partially submerged in the second aqueous solution; a connecting portion including a connecting passage that communicates the first accommodating space and the second accommodating space, and an ion exchange membrane located in the connecting passage; A power supply device connecting the cathode and anode; In the case of a water electrolysis system including a calcium carbonate generator connected to the first accommodation space and the third accommodation space to generate calcium carbonate (CaCO _{3 (S)} ), when power is supplied to the power supply device, oxygen and chlorine, etc., as well as producing hydrogen and calcium carbonate with high purity.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described in detail with reference to the drawings.

Figure 1 is a schematic diagram showing the water electrolysis process of a water electrolysis system according to an embodiment. Referring to Figure 1, a cathode portion 110 including a first aqueous solution 115 accommodated in the first accommodating space 111, and a cathode 118 at least partially submerged in the first aqueous solution 115; An anode portion 150 including a second aqueous solution 155 accommodated in the second accommodating space 151, and an anode 158 at least partially submerged in the second aqueous solution; A power supply device 160 connecting the cathode 118 and anode 158; a connecting portion 190 including a connecting passage 191 that communicates the first accommodating space 111 and the second accommodating space 151, and an ion exchange membrane 192 provided in the connecting passage; And a calcium carbonate generating unit 120 connected to the first accommodating space 111 and the second accommodating space 151 to generate calcium carbonate (CaCO _{3 (S)} ).

The cathode portion 110 may include a first aqueous solution 115 accommodated in the first accommodation space 111, and a cathode 118 that is at least partially submerged in the first aqueous solution 115.

The first aqueous solution 115 is an aqueous electrolyte. Specifically, it may be an alkaline aqueous solution in which an alkali metal hydroxide (e.g., LiOH, NaOH, or KOH) is dissolved in water, and is preferably an alkaline aqueous solution in which carbon dioxide is easily dissolved. It may be an aqueous KOH solution.

According to one embodiment, the first aqueous solution 115 may be obtained by eluting CO ₂ from a strong basic solution of 1M KOH.

The cathode 118 is an electrode for forming a water electrolysis system and may be a reduction electrode that receives electrons (e ^- ) and generates hydrogen gas (H ₂ ).

Specifically, the cathode 118 may be a material that can cause a reduction reaction through electrons (e ^- ) generated when power is supplied to the power supply device.

According to one embodiment, the cathode 118 may be one or more selected from the group consisting of carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, and metal thin film.

The cathode 118 may further include a catalyst within the cathode to promote the reduction reaction. Specifically, it may include a hydrogen evolution reaction catalyst.

In one embodiment, the cathode 118 may include one or more selected from the group consisting of a platinum catalyst, a carbon-based catalyst, a carbon-metal composite catalyst, and a perovskite oxide catalyst, preferably , it may further include a platinum catalyst known to have the highest catalytic activity for the hydrogen generation reaction in an aqueous electrolyte.

The cathode portion 110 may further include a first inlet 112, a first outlet 113, and a first connector 114 that communicate with the first receiving space 111.

The first inlet 112 may be located at the lower part of the first receiving space 111 so as to be located below the water surface of the first aqueous solution 115. The first outlet 113 may be located at the upper part of the first receiving space 111 so as to be above the water surface of the first aqueous solution 115. Carbon dioxide, which is used as a raw material during the discharge process, flows into the first receiving space 111 through the first inlet 112, and when necessary, the first aqueous solution 115 can also flow in. Gas generated during the water electrolysis process can be discharged to the outside through the first outlet 113. Although not shown, the inlet 112 and outlet 113 may be selectively opened and closed at appropriate times by a valve or the like during charging and discharging. The first connector 114 is located below the water surface of the first aqueous solution 115, and a connector 190 is connected to the first connector 114. A carbon dioxide elution reaction may occur in the cathode 110 during the water electrolysis process.

The anode 150 may include a second aqueous solution 155 accommodated in the second accommodating space 151, and an anode 158 at least partially submerged in the second aqueous solution 155, and preferably, the electronic It may be an oxidation electrode part where an oxidation reaction that generates (e ^- ) occurs.

The second aqueous solution 155 is an aqueous electrolyte. Specifically, it may be an alkaline aqueous solution in which an alkali metal hydroxide (e.g., LiOH, NaOH, or KOH) is dissolved in water, and is preferably oxidized through an oxygen generation reaction. It may be a high-concentration KOH aqueous solution that facilitates the reduction reaction.

According to one embodiment, the second aqueous solution 155 may be a 1M KOH or 6M KOH strongly basic solution.

The anode 158 may have one side in contact with the second electrolyte 155, but is preferably positioned so that at least part of the anode 158 is submerged in the second electrolyte 155.

The anode 158 is an oxidizing electrode that forms a water electrolysis system, and can generate electrons (e ^- ) through the oxidation reactions of oxygen evolution reaction (OER) and chlorine evolution reaction (CER), and preferably, generate oxygen. Reaction (Oxygen Evolution Reaction, OER) catalyst may be included.

According to one embodiment, the oxygen generation reaction catalyst included in the anode may be one or more selected from the group consisting of a metal oxide catalyst, a perovskite oxide catalyst, a metal sulfide catalyst, a metal carbide catalyst, and a carbon catalyst, wherein , the metal contained in the oxygen evolution reaction catalyst is selected from the group consisting of Li, Co, Ni, Zn, Fe, Ti, Na, Mn, Cu, Ga, Sn, Cr, W, Ru, Ir, Pt, and Au. There may be at least one type.

The anode unit 150 may further include a third inlet 127, a second outlet 153, and a second connector 154 that communicate with the second accommodation space 151.

The third inlet 127 may be located at the lower part of the second receiving space 151 so as to be located below the water surface of the second aqueous solution 155. The second outlet 153 may be located at the upper part of the second receiving space 151 so as to be above the water surface of the second aqueous solution 155.

The remaining liquid remaining after generating calcium carbonate in the calcium carbonate (CaCO _{3 (S)} ) generating unit 120 may be injected into the second receiving space 151 through the third inlet 127. Oxygen (O ₂ ) and chlorine (Cl ₂ ), which are gases generated when power is supplied to the power supply device, may be discharged to the outside through the second outlet 153. Although not shown, the third inlet 127 and the second outlet 153 may be selectively opened and closed at appropriate times by a valve or the like when the power supply device is supplied with power.

The anode portion 150 may be formed with a second connector 154 that communicates with the second receiving space 151. The second connector 154 is located below the water surface of the second aqueous solution 155, and the connector 190 may be connected to the second connector 154.

The connection part 190 is a connection passage 191 connecting the first accommodation space 111 of the cathode unit 110 and the second accommodation space 151 of the anode unit 150, and the interior of the connection passage 191. It may be provided with an ion exchange membrane (membrane) 192 installed in the.

Specifically, the connection passage 191 extends between the first connector 114 formed in the cathode portion 110 and the second connector 154 formed in the anode portion 150 to connect the first connector 114 of the cathode portion 110. The receiving space 111 and the second receiving space 151 of the anode unit 150 may be connected. An ion exchange membrane 192 may be provided inside the first connection passage 191.

The ion exchange membrane 192 may be installed to block the interior of the connection passage 191. The ion exchange membrane 192 only allows the movement of ions between the cathode portion 110 and the anode portion 150, thereby resolving ion imbalance occurring during the water electrolysis process.

Specifically, alkali metal ions, specifically potassium ions (K ⁺ ), contained in the second electrolyte solution 155 can move to the first electrolyte solution 115 by the ion exchange membrane 192.

According to one embodiment, Nafion, a fluororesin-based cation exchange membrane developed by DuPont in the United States, may be used as the ion exchange membrane 192.

The calcium carbonate generating unit 120 includes a reactor 121 that generates calcium carbonate (CaCO _3(S) ); A first inlet 123 that connects the first accommodation space 111 and the reactor 121 and injects bicarbonate ions (HCO ₃ ^- ) in the first accommodation space 111 into the reactor 121; A second inlet 125 connected to the reactor 121 and introducing calcium ions (Ca ²⁺ ) into the reactor 121; and a third inlet 127 that connects the second accommodation space 151 and the reactor 121 and injects the remaining liquid after the calcium carbonate (CaCO _3(S) ) production reaction into the second accommodation space 151; may include.

The first inlet 123 connects the first accommodating space 111 and the reactor 121, and bicarbonate ions (HCO ₃ ^- ), which are the product after reaction in the first accommodating space 111, are converted into calcium carbonate (CaCO _3(S) ) can be introduced into the reactor 121 of the production unit 120.

According to one embodiment, KHCO _3(aq), which is a product after reaction in the first receiving space 111, may be introduced into the reactor 121.

The second inlet 125 is connected to the reactor 121, and reacts with bicarbonate ions (HCO ₃ ^- ) introduced into the reactor 121 through the first inlet 123 to produce calcium carbonate (CaCO _{3 (S).} ) Calcium ions (Ca ²⁺ ) that can generate can be introduced.

According to one embodiment, CaCl _2(aq) may be added to the reactor 121.

The reactor 121 reacts with bicarbonate ions (HCO ₃ ^- ) introduced from the first inlet 123 and calcium ions (Ca ²⁺ ) introduced from the second inlet 125 to produce calcium carbonate (CaCO _{3 (S)} ) is produced, and residues may remain after the production reaction.

According to one embodiment, the residue may be KCl _(aq) .

The third inlet 127 is connected to the second receiving space 151 and the reactor 121, and the remaining liquid after the production reaction in the reactor 121 is injected into the second receiving space 151 to form the anode 158. It is possible to provide a solution that progresses the oxygen evolution reaction (OER) and the chlorine evolution reaction (CER).

Figure 2 is a schematic diagram showing the water electrolysis process of a water electrolysis system according to another embodiment. Referring to FIG. 2, the secondary battery 100a includes a cathode portion 110, an anode portion 150, a connection portion 190 connecting the cathode portion 110 and the anode portion 150, and a cathode portion 110. 1 Calcium carbonate generating unit 120, carbon dioxide processing unit 130, carbon dioxide circulation supply unit 135, and cathode unit 110 connecting the accommodation space 111 and the second accommodation space 151 of the anode unit 150. It may include a first connection pipe 140 that communicates with the carbon dioxide treatment unit 130.

Among the content related to the cathode portion 110, anode portion 150, connection portion 190, and calcium carbonate generating portion 120, content that overlaps with the content described in the water electrolysis system shown in FIG. 1 can be omitted. there is.

The carbon dioxide processing unit 130 may be in communication with the first accommodation space 111.

The third aqueous solution 135 accommodated in the third accommodating space 131 in the carbon dioxide treatment unit 130 may be the same aqueous solution as the first aqueous solution 115 of the cathode unit 110.

The carbon dioxide treatment unit 130 includes a second inlet 132 through which carbon dioxide flows into the third accommodation space 131, a communication port (not shown) to which the connection pipe 140 is connected, and a third accommodation space 131. It may include a third outlet 133 located at the top.

The second inlet 132 may be located above the communication port (not shown) in the fourth receiving space 131 and below the water level of the third outlet 133 and the third aqueous solution 135. Carbon dioxide gas, which is used as a fuel in the water electrolysis process, can flow into the third receiving space 131 through the second inlet 132, and a third aqueous solution 135 can also be supplied through the second inlet 132 as needed. can be supplied.

The third outlet 133 is located above the water level of the second inlet 132 and the third aqueous solution 135 in the third accommodation space 131. Carbon dioxide gas that is not dissolved in the fourth aqueous solution 135 in the fourth accommodating space 131 through the third outlet 133 and thus is not ionized floats to the top due to the difference in specific gravity and is finally discharged to the outside. Carbon dioxide gas discharged through the third outlet 133 may be supplied to the second inlet 132 through the carbon dioxide circulation supply unit 135.

This has the advantage of increasing the purity of hydrogen (H ₂ ) gas discharged from the first outlet 113. In other words, the existing method did not include a separate carbon dioxide treatment unit, so there was a disadvantage in that unionized carbon dioxide gas and hydrogen gas generated from the secondary battery were mixed and discharged, lowering the purity. However, the water electrolysis system according to another embodiment has a carbon dioxide treatment unit 130, so that among the carbon dioxide introduced into the third accommodation space 131, the carbon dioxide gas that is not dissolved in the third aqueous solution and thus not ionized is disposed of in the cathode unit 110. Unable to move to the first receiving space 111, the non-ionized carbon dioxide gas is discharged separately through the third outlet 133, making a difference from the first outlet 113 through which hydrogen gas generated in the water electrolysis system is discharged. There is an advantage in obtaining high purity hydrogen gas.

Meanwhile, the second inlet 132 and the first outlet 113 may be selectively opened and closed at appropriate times by a valve or the like during charging and discharging.

The communication port (not shown) is located below the second inlet 132 in the third receiving space 131, and a connection pipe 140 may be connected to the communication port (not shown). The third accommodation space 131 may be in communication with the first accommodation space 111 through the connection pipe 140 connected to the communication port (not shown).

The connection pipe 140 may connect the first inlet 112 of the first accommodation space 111 and the communication port (not shown) of the third accommodation space 131. The first accommodating space 111 and the third accommodating space 121 may be communicated through a connection passage (not shown) formed inside the connecting pipe 140.

The carbon dioxide circulation supply unit 135 may circulate the carbon dioxide gas discharged through the third outlet 133 to the second inlet 132 and re-supply it.

That is, among the carbon dioxide that flows into the fourth accommodation space 131 of the carbon dioxide processing unit 130 through the second inlet 132, the carbon dioxide gas that is not ionized because it is not dissolved in the fourth aqueous solution 135 is connected to the first electrode unit 110. ) fails to move to the first accommodation space 111 and rises, collects in the space above the water surface of the fourth aqueous solution 135 in the fourth accommodation space 131, and is then discharged through the third outlet 133 and the third outlet ( The carbon dioxide gas discharged through 133) is supplied to the fourth accommodation space 131 through the second inlet 132 by the carbon dioxide circulation supply unit 135 and is recycled.

Therefore, the secondary battery according to another embodiment has the advantage of increasing the energy efficiency of the battery because it can supply non-ionized carbon dioxide gas to the second inlet 132 through the carbon dioxide circulation supply unit 135.

The water electrolysis process of the water electrolysis system (100, 100a) is as follows. Figure 1 or Figure 2 shows the water electrolysis process of the water electrolysis system (100, 100a). Referring to this, carbon dioxide as a raw material for hydrogen production is injected into the first aqueous solution 115 through the first inlet 112, and a chemical elution reaction of carbon dioxide occurs in the cathode portion 110 as shown in the following [Reaction Formula 1].

[Scheme 1]

H ₂ O(l) + CO ₂ (g) → H ⁺ (aq) + HCO ₃ ^- (aq)

^{That is, the cathode unit 110 produces hydrogen cations (H +} _{) and} bicarbonate ( HCO ₃ ^- ) can be produced.

Additionally, an electrical reaction occurs in the cathode portion 110 as shown in [Reaction Formula 2].

[Scheme 2]

2H ⁺ (aq) + 2e ^- → H ₂ (g)

That is, in the cathode portion 110, hydrogen positive ions (H+) receive electrons (e ^- ) and hydrogen (H ₂ ) gas is generated. The generated hydrogen (H ₂ ) gas is discharged to the outside through the first outlet 113.

In summary, a complex hydrogen generation reaction occurs in the cathode portion 110 as shown in [Reaction Formula 3].

[Scheme 3]

2H ₂ O(l) + 2CO ₂ (g) + 2e ^- → H ₂ (g) + 2HCO ₃ ^- (aq)

The aqueous solution containing bicarbonate (HCO ₃ ^- ) generated from the complex hydrogen generation reaction may be introduced into the reactor 121 of the calcium carbonate (CaCO _{3 (S)} ) production unit through the first inlet 123 along with positive ions.

At this time, the cation contained in the aqueous solution containing bicarbonate may be one or more types selected from the group consisting of potassium cation (K ⁺ ), sodium cation (Na ⁺ ), lithium (Li ⁺ ), and magnesium (Mg ⁺ ).

According to one embodiment, an aqueous solution of KHCO _{3 (aq)} may be introduced into the reactor 121.

Bicarbonate (HCO ₃ ^- ) introduced into the reactor 121 is an aqueous solution containing calcium ions (Ca ²⁺ ) introduced into the reactor through the second inlet 125 and a calcium carbonate production reaction as shown in [Reaction Formula 4]. It comes true.

[Scheme 4]

2 KHCO _3(aq) + CaCl _2(aq) → 2 KCl _(aq) + CO _2(g) + CaCO _3(s) + H ₂ O _(l)

or

K ₂ CO _3(aq) + CaCl _2(aq) → 2 KCl _(aq) + CaCO _3(s)

At this time, the anion contained in the aqueous solution containing calcium ion (Ca ²⁺ ) is selected from the group consisting of chlorine anion (Cl ^- ), hydroxide ion (OH ^- ), fluorine (F ^- ), and bromine (Br ^- ). There may be more than one type.

According to one embodiment, an aqueous CaCl _{2 (aq)} solution may be introduced into the reactor 121.

After the calcium carbonate production reaction, the remaining liquid may be injected into the anode unit 150 through the third inlet 127.

At this time, it may include cations contained in an aqueous solution containing bicarbonate and anions contained in an aqueous solution containing calcium ions (Ca ²⁺ ).

According to one embodiment, it may be an aqueous KCl _(aq) solution.

And, in the anode unit 150, the remaining liquid after the calcium carbonate generation reaction injected from the third inlet 127 undergoes an oxidation reaction of oxygen evolution reaction (OER) as shown in [Reaction Formula 5].

[Scheme 5]

4 OH ^- _(aq) → O _2(g) + 2H ₂ O _(l) + 4 e ^-

Meanwhile, if the remaining liquid after the calcium carbonate generation reaction injected from the third inlet 127 contains chlorine ions (Cl-), the oxidation reaction of the chlorine generation reaction as shown in the following [Reaction Formula 6] also occurs.

[Scheme 6]

2 Cl ^- _(aq) → Cl _2(g) + 2 e ^-

In other words, the water electrolysis system according to one aspect has the advantage of being able to produce not only oxygen and chlorine, but also hydrogen and calcium carbonate with high purity.

100, 100a: Water electrolysis system
110: cathode part
120: Calcium carbonate production unit
130: carbon dioxide processing unit
140: connector
150: anode part
160: power supply device

Claims (16)

a cathode portion including a first aqueous solution contained in a first accommodating space, and a cathode (anode) at least partially submerged in the first aqueous solution;
an anode portion including a second aqueous solution contained in a second accommodating space and a metal anode at least partially submerged in the second aqueous solution;
A power supply device connecting the cathode and anode;
a connecting portion including a connecting passage that communicates the first accommodating space and the second accommodating space, and an ion exchange membrane located in the connecting passage; and
It includes a calcium carbonate generating unit connected to the first accommodating space and the third accommodating space to generate calcium carbonate (CaCO _{3 (S)} ),
When power is supplied to the power supply device, carbon dioxide gas flows into the first electrolyte from the cathode, and hydrogen ions (H ⁺ ) and bicarbonate ions (HCO ₃ ^- ) are generated by the reaction of the first electrolyte and the carbon dioxide gas. , A water electrolysis system characterized in that hydrogen gas (H ₂ ) is generated by combining the hydrogen ions (H ⁺ ) and electrons (e ^- ) supplied by power supply. According to paragraph 1,
The calcium carbonate producing unit
A reactor for producing calcium carbonate (CaCO _3(S) );
A first inlet connecting the first accommodation space and the reactor and introducing bicarbonate ions (HCO ₃ ^- ) from the first accommodation space into the reactor;
A second inlet connected to the reactor and introducing calcium ions (Ca ²⁺ ) into the reactor; and
A third inlet connects the third accommodating space and the reactor and injects the remaining liquid after the calcium carbonate (CaCO _{3 (S)} ) production reaction into the third accommodating space,
Water electrolysis system. According to paragraph 1,
A water electrolysis system wherein the anode includes an oxygen evolution reaction catalyst. According to paragraph 3,
The oxygen generation reaction catalyst is
A water electrolysis system comprising at least one selected from the group consisting of metal oxide catalysts, perovskite oxide catalysts, metal sulfide catalysts, metal carbide catalysts, and carbon catalysts. According to paragraph 4,
The metal contained in the oxygen generation reaction catalyst is
A water electrolysis system comprising at least one selected from the group consisting of Li, Co, Ni, Zn, Fe, Ti, Na, Mn, Cu, Ga, Sn, Cr, W, Ru, Ir, Pt, and Au. According to paragraph 1,
The water electrolysis system wherein the cathode includes carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, and metal thin film. According to clause 6,
The water electrolysis system wherein the cathode further includes a hydrogen evolution reaction catalyst. According to paragraph 1,
The carbon dioxide processing unit
A water electrolysis system further comprising a carbon dioxide treatment unit that communicates with the first accommodation space and includes a third aqueous solution accommodated in the third accommodation space. According to clause 8,
The carbon dioxide processing unit
A water electrolysis system that separates un-ionized carbon dioxide gas from the carbon dioxide gas flowing into the third receiving space from the third aqueous solution and prevents it from being supplied to the anode part. According to clause 8,
The carbon dioxide processing unit
A water electrolysis system that separates the non-ionized carbon dioxide gas using the difference in specific gravity from the third aqueous solution. According to clause 8,
The carbon dioxide processing unit
an inlet located below the water surface of the third aqueous solution in the third accommodation space and through which carbon dioxide gas flows; and
The water electrolysis system further includes; a communication port located below the inlet and formed to communicate with the first accommodating space in the third accommodating space. According to paragraph 1,
The cathode part
The water electrolysis system further includes a first outlet located above the water surface of the first aqueous solution accommodated in the first accommodation space and discharging hydrogen gas generated during discharge. According to clause 8,
The carbon dioxide processing unit
The water electrolysis system is located above the water surface of the third aqueous solution in the third accommodation space and further includes a second outlet through which the non-ionized carbon dioxide gas is discharged during discharge. According to clause 8,
The carbon dioxide processing unit
A water electrolysis system further comprising a carbon dioxide circulation supply unit that resupplies the non-ionized carbon dioxide gas to the third aqueous solution in the third accommodation space. According to paragraph 1,
A water electrolysis system wherein the first aqueous solution or the second aqueous solution is an alkaline aqueous solution containing alkaline metal ions. According to clause 15,
A water electrolysis system in which alkaline metal ions in the second accommodation space move to the first accommodation space through an ion exchange membrane.