Hydrogen production and carbon dioxide storage system with improved carbon dioxide processing capability

Abstract

The present invention relates to a hydrogen production and carbon dioxide storage system that increases the handling capacity of carbon dioxide. The system comprises a metal-carbon dioxide battery, wherein the metal-carbon dioxide battery comprises a negative electrode, a positive electrode and an ion exchange membrane positioned between the negative electrode and the positive electrode; a first supply unit configured to supply a first electrolyte solution to the negative electrode; a second supply unit configured to supply a second electrolyte solution including hydrogen ions and an alkali metal bicarbonate aqueous solution to the positive electrode; a separation unit; the electrolyte circulating unit is positioned at the rear end of the separation unit; the dissolving unit is positioned at the rear end of the electrolyte circulating unit; and a carbon dioxide purification unit.

Description

Technical Field

[0001] The present invention relates to a hydrogen production and carbon dioxide storage system with improved carbon dioxide processing capabilities. Background Art

[0002] In recent years, with the development of renewable energy, electrochemical water electrolysis has been actively studied to combat climate change. 2 ) capture, storage and conversion technologies are becoming increasingly important for reducing greenhouse gases.

[0003] In terms of price and reserves, the zinc / aluminum (Zn / Al) based aqueous battery system is a very economical metal cathode candidate. The zinc / aluminum (Zn / Al) based aqueous battery system is a kind of battery that produces hydrogen and uses potassium bicarbonate (KHCO 3 ) and other salts to capture carbon dioxide.

[0004] The above information disclosed in this Background section is only provided for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0005] The present invention is directed to solving the above-mentioned problems associated with the prior art.

[0006] An object of the present invention is to provide a hydrogen production and carbon dioxide storage system having a higher carbon dioxide processing capacity than conventional systems.

[0007] Another object of the present invention is to provide a hydrogen production and carbon dioxide storage system having a greater production capacity of alkali metal bicarbonate than conventional systems.

[0008] The object of the present invention is not limited to the above-mentioned object. The object of the present invention will be clearly understood from the description of the following embodiments, and can be achieved by the manner defined in the claims and their combinations.

[0009] In one aspect, the present invention provides a hydrogen production and carbon dioxide storage system, which includes a metal-carbon dioxide battery, the metal-carbon dioxide battery including an anode, a cathode, and an ion exchange membrane between the anode and the cathode; a first supply unit, the first supply unit is configured to provide a first electrolyte to the anode; a second supply unit, the second supply unit is configured to provide a second electrolyte including hydrogen ions and an alkali metal bicarbonate aqueous solution to the cathode; a separation unit, the separation unit is configured to separate the product discharged from the cathode into hydrogen and circulating liquid; an electrolyte circulation unit, which is located at the rear end of the separation unit, wherein the electrolyte circulation unit is configured to receive and store the circulating liquid from the separation unit; a dissolution unit, which is located at the rear end of the electrolyte circulation unit, wherein the dissolution unit is configured to dissolve carbon dioxide in the starting material received from the electrolyte circulation unit to produce an electrolyte precursor solution; and a carbon dioxide purification unit, which is configured to purify carbon dioxide from a gas mixture including carbon dioxide supplied from the outside and provide the carbon dioxide to the dissolution unit.

[0010] The system may further include a filtration unit located between the second supply unit and the dissolution unit, wherein the filtration unit is configured to precipitate and separate alkali metal bicarbonate from the electrolyte precursor solution received from the dissolution unit to produce a second electrolyte and provide the second electrolyte to the second supply unit.

[0011] The negative electrode may include at least one selected from the group consisting of aluminum, zinc, and a combination thereof.

[0012] The positive electrode may include at least one selected from the group consisting of carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal thin film, and a combination thereof, or may include a catalyst metal supported on a carrier.

[0013] The ion exchange membrane may include a cation conductive resin.

[0014] The first electrolyte may include at least one selected from the group consisting of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a combination thereof.

[0015] The second electrolyte may have a pH of 7 to 9.

[0016] The alkali metal bicarbonate aqueous solution may include a 3 ) aqueous solution, potassium bicarbonate (KHCO 3 ) aqueous solution and their combination consisting of at least one.

[0017] The alkali metal bicarbonate aqueous solution included in the second electrolyte may have a concentration of 0.5M to 2M.

[0018] The carbon dioxide purification unit may include: an absorbent storage module configured to store an absorbent including an aqueous solution of alkali metal carbonate; an intake module configured to dissolve carbon dioxide of a gas mixture in the absorbent received from the absorbent storage module to produce a concentrate; a degassing module configured to degas carbon dioxide from the concentrate received from the intake module and provide the carbon dioxide to a dissolution unit; and an effluent distribution module configured to receive effluent discharged from the degassing module, provide part of the effluent to an electrolyte circulation unit, and provide the remaining effluent to the absorbent storage module.

[0019] The aqueous solution of alkali metal carbonate may include a 2 CO 3 ) aqueous solution, potassium carbonate (K 2 CO 3 ) aqueous solution and their combination consisting of at least one.

[0020] The alkali metal carbonate aqueous solution included in the absorbent may have a concentration of 0.01M to 1M.

[0021] The gas mixture may include at least one selected from the group consisting of steel by-product gas, exhaust gas, and combinations thereof.

[0022] The intake module may include an intake separator installed therein, which is configured to separate the internal space of the intake module into an absorbent flow space and a gas mixture flow space; and the carbon dioxide included in the gas mixture flowing in the gas mixture flow space can pass through the intake separator and can be dissolved in the absorbent flowing in the absorbent flow space.

[0023] The ratio of the flow rate of the absorbent to the gas mixture provided to the intake module may be 1:0.001 to 1:5.

[0024] The ratio of the pressure of the absorbent to the gas mixture provided to the intake module may be 1:0.1 to 1:3.

[0025] The amount of carbon dioxide included in the residual gas exhausted from the intake module may be 0.1 wt % or less.

[0026] The degassing module may include a degassing separator installed therein, the degassing separator being configured to separate an internal space of the degassing module into a concentrate flow space and a carbon dioxide degassing space, and carbon dioxide included in the concentrate flowing in the concentrate flow space may pass through the degassing separator and may be discharged to the carbon dioxide degassing space.

[0027] The carbon dioxide exhausted from the degassing module may have a purity of 99.9% by volume or more.

[0028] The effluent distribution module may provide a portion of the effluent to the electrolyte circulation unit, and in the electrolyte circulation unit, the portion of the effluent may be mixed with the circulating liquid and stored as a starting material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments of the invention shown in the accompanying drawings, which are given hereinafter by way of illustration only and therefore do not limit the present invention, wherein:

[0030] Figure 1 A hydrogen production and carbon dioxide storage system according to the present invention is shown;

[0031] Figure 2 shows a carbon dioxide purification unit according to the present invention;

[0032] Figure 3 An air intake module according to the present invention is shown;

[0033] Figure 4 A degassing module according to the present invention is shown;

[0034] Figure 5 Showing a dissolution unit according to the invention;

[0035] Figure 6 shows the measurement results of the carbon dioxide concentration exhausted from the carbon dioxide purification unit according to Example 1;

[0036] Figure 7 shows the measurement results of the carbon dioxide concentration exhausted from the carbon dioxide purification unit according to Example 2;

[0037] Figure 8 The measurement results of the carbon dioxide concentration exhausted from the carbon dioxide purification unit according to Example 3 are shown.

[0038] It should be understood that the accompanying drawings are not necessarily drawn to scale, and that they present a somewhat simplified representation of various preferred features that illustrate the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the specific intended application and use environment.

[0039] In the drawings, reference characters refer to the same or equivalent parts of the present invention throughout the various figures of the drawing. DETAILED DESCRIPTION

[0040] The above objects and other objects, features and advantages will be clearly understood by referring to the following preferred embodiments of the accompanying drawings. However, the present invention is not limited to these embodiments and will be embodied in different forms. On the contrary, the embodiments are provided only to provide a thorough and complete understanding of the disclosed content and to fully inform those skilled in the art of the technical concept of the present invention.

[0041] Throughout the description of the accompanying drawings, the same reference numerals refer to the same elements. In the accompanying drawings, the size of the structure is magnified for clarity. It should be understood that although the terms "first", "second", etc. can be used to describe various elements in this article, the corresponding elements should not be understood to be limited by these terms, which are only used to distinguish one element from another element. For example, within the scope defined by the present invention, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form.

[0042] It should also be understood that when the terms "comprises", "has", etc. are used in this specification, the existence of the stated features, numbers, steps, operations, elements, components, or combinations thereof is explicitly indicated, but the existence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof is not excluded. In addition, it should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly above the other element or there can be intervening elements. It should also be understood that when an element such as a layer, film, region, or substrate is referred to as being "under" another element, it can be directly under the other element or there can be intervening elements.

[0043] Unless the context clearly indicates otherwise, all numbers, values ​​and / or expressions representing ingredients, reaction conditions, polymer compositions and mixture amounts used in this specification are approximate values, which reflect the various measurement uncertainties inherent in the process of obtaining these values, etc. Therefore, it should be understood that the term "about" should modify all numbers, values ​​and / or expressions in any case. In addition, when a numerical range is disclosed in the specification, unless otherwise defined, these ranges are continuous and include all numbers from the minimum to the maximum within the range, including the maximum. In addition, when a range involves an integer, unless otherwise defined, it includes all integers from the minimum to the maximum within the range, including the maximum.

[0044] Figure 1 The hydrogen production and carbon dioxide storage system according to the present invention is shown. The system may include a metal-carbon dioxide battery 10, the metal-carbon dioxide battery 10 including a negative electrode 11, a positive electrode 12 and an ion exchange membrane 13 located between the negative electrode 11 and the positive electrode 12; a first supply unit 20, the first supply unit 20 is configured to provide a first electrolyte A to the negative electrode 11; and a second supply unit 30, the second supply unit 30 is configured to provide a second electrolyte B to the positive electrode 12.

[0045] The negative electrode 11 is an electrode made of a metal material, and the metal material may include at least one selected from the group consisting of aluminum, zinc, and a combination thereof.

[0046] The first supply unit 20 may include a tank configured to receive the first electrolyte A and a pump configured to supply the first electrolyte A to the negative electrode 11 .

[0047] The first electrolyte A may include at least one selected from the group consisting of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a combination thereof.

[0048] At the negative electrode 11, an oxidation reaction such as the following reaction formula 1-1 or reaction formula 1-2 may occur. The following reaction formula 1-1 and reaction formula 1-2 are based on the case where the negative electrode 11 is zinc. Reaction formula 1-1: Zn+4Na + +4OH - →4Na + +Zn(OH) 4 2- +2e - Zn(OH) 4 2- →ZnO+H 2 O+2OH - Reaction 1-2: Zn+4K + +4OH - →4K + +Zn(OH) 4 2- +2e - Zn(OH) 4 2- →ZnO+H 2 O+2OH -

[0049] Alkali metal oxide such as zinc oxide generated at the negative electrode 11 is discharged to the outside, and alkali metal cations move to the positive electrode 12 through the ion exchange membrane 13 .

[0050] The ion exchange membrane 13 may be located between the negative electrode 11 and the positive electrode 12 to prevent physical contact therebetween. In addition, the ion exchange membrane 13 may prevent mixing between the first electrolyte A and the second electrolyte B, and may conduct alkali metal cations generated from the negative electrode 11 to the positive electrode 12.

[0051] The ion exchange membrane 13 may include a cation conductive resin. For example, the ion exchange membrane 13 may include a perfluorosulfonic acid-based resin such as Nafion.

[0052] The positive electrode 12 may cause a reaction between the alkali metal cations moving through the ion exchange membrane 13 and the second electrolyte B to generate hydrogen gas, and may store carbon dioxide in the form of alkali metal bicarbonate.

[0053] The positive electrode 12 as an electrode may include at least one selected from the group consisting of carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal film and a combination thereof, or may include a catalyst metal supported on a carrier. Although not particularly limited, the catalyst metal may include a noble metal such as platinum (Pt), and / or a transition metal such as nickel (Ni) or molybdenum (Mo).

[0054] The second supply unit 30 may include a tank configured to receive the second electrolyte B and a pump configured to provide the second electrolyte B to the positive electrode 12 .

[0055] The second electrolyte B may include hydrogen ions, an alkali metal bicarbonate aqueous solution, and carbon dioxide. The second electrolyte B may also include an alkali metal carbonate aqueous solution which will be described later.

[0056] The alkali metal bicarbonate aqueous solution may include a 3 ) aqueous solution, potassium bicarbonate (KHCO 3 ) aqueous solution and their combination consisting of at least one.

[0057] The aqueous alkali metal carbonate solution may include a 2 CO 3 ) aqueous solution, potassium carbonate (K 2 CO 3 ) aqueous solution and their combination consisting of at least one.

[0058] When the second electrolyte B is supplied to the positive electrode 12, hydrogen is generated according to the following reaction formula 2, and carbon dioxide is stored in the form of salt according to the following reaction formulas 3-1 and 3-2: Reaction 2: 2H + +2e - →H 2 Reaction 3-1: 2Na + +Na 2 CO 3 +3CO 2 +3H 2 O→4Na + +4HCO 3 - +2H + →4NaHCO 3 + 2H + Na + +HCO 3 - →NaHCO 3 Reaction 3-2: 2K + +K 2 CO 3 +3CO 2 +3H 2 O→4K + +4HCO 3 - +2H + →4KHCO 3 +2H + K + +HCO 3 - →KHCO 3

[0059] Therefore, the product C discharged from the positive electrode 12 may include unreacted substances of the second electrolyte B, hydrogen gas, and an alkali metal bicarbonate aqueous solution.

[0060] The system may include a separation unit 40, which is configured to separate the product C discharged from the positive electrode 12 into hydrogen and a circulating liquid C'; an electrolyte circulation unit 50, which is located at the rear end of the separation unit 40 and is configured to receive and store the circulating liquid C' from the separation unit 40; a dissolution unit 60, which is located at the rear end of the electrolyte circulation unit 50 and is configured to dissolve carbon dioxide in a starting material D received from the electrolyte circulation unit 50 to produce an electrolyte precursor solution F; and a filtration unit 70, which is located between the second supply unit 30 and the dissolution unit 60, and is configured to precipitate and separate alkali metal bicarbonate from the electrolyte precursor solution F received from the dissolution unit 60 to produce a second electrolyte B and provide the second electrolyte B to the second supply unit 30.

[0061] Furthermore, the system may include a carbon dioxide purification unit 80 configured to purify carbon dioxide E from a gas mixture including carbon dioxide supplied from the outside and provide the carbon dioxide E to the dissolving unit 60 .

[0062] In the present invention, based on the flow of the gas mixture, the carbon dioxide can be processed sequentially by the carbon dioxide purification unit 80 located at the front end and the dissolution unit 60 located at the rear end, thereby increasing the processing capacity of the carbon dioxide. In addition, since the high-purity carbon dioxide E that has passed through the carbon dioxide purification unit 80 is provided to the dissolution unit 60, the processing pressure, flow rate, etc. can be reduced, so the scale of the dissolution unit 60 can be greatly reduced.

[0063] Figure 2 A carbon dioxide purification unit 80 according to the present invention is shown. The carbon dioxide purification unit 80 may include an absorbent storage module 81 configured to store an absorbent G1 including an alkali carbonate aqueous solution; an intake module 82 configured to dissolve carbon dioxide of a gas mixture in the absorbent G1 received from the absorbent storage module 81 to produce a concentrate G2; a degassing module 83 configured to degas carbon dioxide E from the concentrate G2 received by the intake module 82 and provide the carbon dioxide E to the dissolution unit 60; and an effluent distribution module 84 configured to receive the effluent G3 discharged from the degassing module 83 to provide a portion of the effluent G4 to the electrolyte circulation unit 50 and provide the remaining effluent G5 to the absorbent storage module 81.

[0064] The aqueous alkali metal carbonate solution may include a2 CO 3 ) aqueous solution, potassium carbonate (K 2 CO 3 ) aqueous solution and their combination consisting of at least one.

[0065] The concentration of the alkali metal carbonate aqueous solution contained in the absorbent G1 may be 0.01 M to 1 M, or 0.1 M to 0.5 M. A low concentration alkali metal carbonate aqueous solution should be used as the absorbent G1 to increase the solubility and selectivity of carbon dioxide contained in the gas mixture.

[0066] The carbon dioxide purification unit 80 may further include an absorbent provision unit (not shown) configured to supply the absorbent G1 to the absorbent storage module 81 .

[0067] Figure 3 An intake module 82 according to the present invention is shown. The intake module 82 may include an intake membrane 821 installed therein. The intake membrane 821 may separate the inner space of the intake module 82 into an absorbent flow space 822 and a gas mixture flow space 823.

[0068] The absorbent G1 may be supplied to the absorbent flow space 822, and the external gas mixture including carbon dioxide may be supplied to the gas mixture flow space 823. The absorbent G1 and the gas mixture may flow in a counter flow form having opposite flow directions. Figure 3 , when the absorbent G1 is supplied to the upper portion of the intake module 82 and the absorbent G1 is discharged to the lower portion of the intake module 82, the gas mixture may be supplied to the lower portion of the intake module 82 and the gas mixture may be discharged to the upper portion of the intake module 82. This may be used to increase the contact time between the absorbent G1 and the gas mixture.

[0069] The intake membrane 821 may include hollow fibers made of a polyolefin-based material such as polypropylene. The surface of the intake membrane 821 may include micropores so that the gas mixture can pass through the intake membrane 821 while the absorbent G1 cannot diffuse.

[0070] The gas mixture may refer to a mixture of carbon dioxide, nitrogen, oxygen, hydrogen, etc. Specifically, the gas mixture may include at least one selected from the group consisting of steel by-product gas, exhaust gas, and a combination thereof.

[0071] Carbon dioxide in the gas mixture has high solubility in the absorbent G1 under high pressure, but remaining gases, such as nitrogen and oxygen, have low solubility in the absorbent G1. Therefore, at the interface between the gas mixture and the intake membrane 821, carbon dioxide passes through the intake membrane 821 and is dissolved and separated in the absorbent G1, and the remaining gas is discharged as residual gas.

[0072] Carbon dioxide can be dissolved in the absorbent G1 according to the following reaction formula 4, which is based on the case where the absorbent G1 is a potassium carbonate aqueous solution. Reaction 4: H 2 O+CO 2 →H + +HCO 3 - K + +CO 3 2- +H + →KHCO 3 K + +HCO 3 - →KHCO 3 Net reaction (Net): K 2 CO 3 +H 2 O+CO 2 →KHCO 3

[0073] Most of the carbon dioxide in the gas mixture may be dissolved in the absorbent G1 in the intake module 82. Specifically, the content of carbon dioxide included in the residual gas exhausted from the intake module 82 may be 0.1 wt% or less.

[0074] The intake module 82 may dissolve carbon dioxide in the absorbent G1 to produce a concentrate G2 , and may provide the concentrate G2 to the degassing module 83 located at a rear end thereof.

[0075] The carbon dioxide absorption rate of the absorbent G1 can be adjusted in various ways. For example, the ratio of the flow rate of the absorbent G1 to the gas mixture provided to the intake module 82 can be adjusted to 1:0.001 to 1:5, or the ratio of the pressure of the absorbent G1 to the gas mixture provided to the intake module 82 can be adjusted to 1:0.1 to 1:3.

[0076] Figure 4A degassing module 83 according to the present invention is shown. The degassing module 83 may include a degassing membrane 831 installed therein. The degassing membrane 831 may separate the inner space of the degassing module 83 into a concentrate flow space 832 and a carbon dioxide degassing space 833.

[0077] The degassing membrane 831 may include hollow fibers made of a polyolefin-based material such as polypropylene. The surface of the degassing membrane 831 may include micropores so that the concentrate G2 cannot pass through but the carbon dioxide E exhausted from the concentrate G2 can pass through.

[0078] The degassing module 83 may degas the carbon dioxide dissolved in the concentrate G2, and may provide the carbon dioxide to the carbon dioxide degassing space 833. More specifically, the concentrate G2 may be provided to the concentrate flow space 832, and the gas in the carbon dioxide degassing space 833 may be discharged to the outside, whereby the pressure in the degassing module 83 may be adjusted so that the carbon dioxide dissolved in the concentrate G2 may be degassed, and thus the concentrate G2 may be separated into the outflow G3 of the degassed carbon dioxide and the carbon dioxide E.

[0079] The pressure in the degassing module 83 may be normal pressure or vacuum, but is not limited thereto, as long as the carbon dioxide in the concentrate G2 can be degassed.

[0080] The purity of the carbon dioxide E discharged from the degassing module 83 may be 99.9% by volume or more. The high-purity carbon dioxide E may be provided to the dissolving unit 60 .

[0081] The effluent G3 may include an alkali metal carbonate aqueous solution as the absorbent G1, and an alkali metal bicarbonate aqueous solution formed by a reaction between the absorbent G1 and carbon dioxide.

[0082] The effluent distribution module 84 may provide a portion of the effluent G4 to the electrolyte circulation unit 50 and the portion of the effluent G4 may be mixed with the circulating liquid C' in the electrolyte circulation unit 50 and stored as the starting material D. The amount of the portion of the effluent G4 is not particularly limited and may be adjusted to a level at which the water consumed according to Reaction Formula 2 and Reaction Formula 3 is supplemented to the metal-carbon dioxide battery 10.

[0083] The effluent distribution module 84 may provide the remaining effluent G5 to the absorbent storage module 81 .

[0084] The system is characterized by including an electrolyte circulation system consisting of a separation unit 40, an electrolyte circulation unit 50, a dissolution unit 60, a filtration unit 70, and a second supply unit 30. As a result, an aqueous solution of alkali metal bicarbonate and / or alkali metal carbonate can be supplied to the positive electrode 12 at a constant concentration to increase the throughput of carbon dioxide and produce alkali metal bicarbonate.

[0085] The separation unit 40 may include a gas-liquid separation device configured to separate hydrogen from a liquid product C exhausted from the positive electrode 12 .

[0086] The separation unit 40 may provide the circulating liquid C' obtained by separating hydrogen from the product C to the electrolyte circulation unit 50. The circulating liquid C' may include unreacted substances of the second electrolyte B and an alkali metal bicarbonate aqueous solution.

[0087] The electrolyte circulation unit 50 may include a storage tank configured to receive a starting material D including a circulation liquid C′ and a portion of the effluent G4 received from the effluent distribution module 84 ; and a pump configured to provide the starting material D to the dissolution unit 60 .

[0088] Figure 5 A dissolution cell 60 according to the present invention is shown. The dissolution cell 60 may include a dissolution separator 61 installed therein. The dissolution separator 61 may separate an inner space of the dissolution cell 60 into an electrolyte flow space 62 and a carbon dioxide flow space 63.

[0089] The starting material D may be provided to the electrolyte flow space 62, and the high-purity carbon dioxide E may be provided to the carbon dioxide flow space 63. The starting material D and the carbon dioxide E may flow in a countercurrent form having opposite flow directions. Figure 5 , when the carbon dioxide E is supplied to the lower part of the dissolution unit 60 and the carbon dioxide E is discharged to the upper part of the dissolution unit 60, the starting material D may be supplied to the upper part of the dissolution unit 60 and the starting material D may be discharged to the lower part of the dissolution unit 60. This may be used to increase the contact time between the carbon dioxide E and the starting material D.

[0090] The dissolving membrane 61 may include hollow fibers made of a polyolefin-based material such as polypropylene. The surface of the dissolving membrane 61 may include micropores so that the starting substance D cannot pass through but the carbon dioxide E can pass through.

[0091] The dissolution reaction of carbon dioxide occurs as shown in the following reaction formula 5 and reaction formula 6. Reaction 5: CO 2 +H 2 O→H+ +HCO 3 - Reaction 6: CO 2 +K 2 CO 3 +H 2 O→2KHCO 3

[0092] The pressure of the carbon dioxide flow space 63 may be adjusted to 1 bar to 10 bar to induce a dissolution reaction of the carbon dioxide E. The dissolution unit 60 may further include a sensor configured to measure the pressure of the carbon dioxide flow space 63 and a pressure control device configured to control the pressure.

[0093] In addition, the ratio of the flow rate of the carbon dioxide E to the flow rate of the starting material D flowing in the dissolving unit 60 may be 1:0.001 to 1:5. When the flow rate ratio is within the above range, the starting material D and the carbon dioxide may effectively contact each other.

[0094] The dissolution unit 60 may supply the electrolyte precursor solution F obtained by the dissolution reaction of the carbon dioxide E to the filtering unit 70. The filtering unit 70 may include a cooler 71 configured to lower the temperature of the electrolyte precursor solution F so that the alkali metal bicarbonate is precipitated from the electrolyte precursor solution F; and a filter 72 configured to separate the precipitated alkali metal bicarbonate. When the cooler 71 lowers the temperature of the electrolyte precursor solution F, the solubility of the alkali metal bicarbonate is reduced, thereby precipitating the alkali metal bicarbonate. The precipitated alkali metal bicarbonate can be easily separated and collected by the filter 72.

[0095] The cooler 71 may cool the electrolyte precursor solution F to about 0°C to 25°C, or 5°C to 10°C.

[0096] The alkali metal bicarbonate can be precipitated and separated from the electrolyte precursor solution F to obtain a second electrolyte B.

[0097] The pH of the second electrolyte B may be pH 7 to pH 9, the temperature thereof may be 0° C. to 25° C., and the concentration of the alkali metal bicarbonate aqueous solution included therein may be 0.5M to 2M.

[0098] Other forms of the present invention will be described in more detail by the following examples. The following examples are illustrative only to assist in understanding the present invention and are not intended to limit the scope of the present invention. Example 1

[0099] like Figure 2As shown in FIG. 1 , a carbon dioxide purification unit was configured. A material including polypropylene hollow fibers was used as each of the intake membrane and the degassing membrane. 0.1 M potassium carbonate (K 2 CO 3 ) aqueous solution as an absorbent. The gas mixture supplied to the air intake module consists of carbon dioxide and nitrogen provided at a flow rate of 1:3. Specifically, carbon dioxide is provided to the air intake module at a flow rate of 3.75 liters / minute and nitrogen is provided at a flow rate of 11.25 liters / minute. The pressure in the air intake module is adjusted to about 6 bar.

[0100] About 50 liters of absorbent are provided to the intake module at a flow rate of about 5 liters / minute, and carbon dioxide is dissolved in the absorbent to obtain a concentrate and residual gas discharged from the intake module. The concentrate is provided to the degassing module to degas the carbon dioxide, and the carbon dioxide and effluent discharged from the degassing module are collected.

[0101] The contents of carbon dioxide and nitrogen in the residual gas discharged from the intake module were measured, and the composition of carbon dioxide discharged from the degassing module was measured. The results are shown in Table 1 below. Comparative Example

[0102] The carbon dioxide purification unit was operated in the same manner as in Example 1, except that a 2M potassium carbonate aqueous solution was used instead of the absorbent. The contents of carbon dioxide and nitrogen in the residual gas according to the comparative example were measured, and the composition of carbon dioxide discharged from the degassing module was measured. The results are shown in Table 1 below. Table 1

[0103] Referring to Table 1, it can be seen that compared with the comparative example, Example 1 using a low concentration absorbent has a higher carbon dioxide absorption rate in the gas mixture and can produce high-purity carbon dioxide in the degassing module.

[0104] Figure 6 The measurement results of the carbon dioxide concentration exhausted from the carbon dioxide purification unit according to Example 1 are shown.

[0105] It can be seen that the initial carbon dioxide dissolution rate is 99.99% and lasts for about 80 minutes. Example 2

[0106] The carbon dioxide purification unit was operated in the same manner as in Example 1, except that a 0.3 M aqueous solution of potassium carbonate was used instead of the absorbent. Figure 7 The measurement results of the carbon dioxide concentration discharged from the carbon dioxide purification unit according to Example 2 are shown. The time point of carbon dioxide emission concentration equilibrium is when all potassium carbonate (K 2 CO 3) is converted into potassium bicarbonate (KHCO 3 ) and the time point at which carbon dioxide is dissolved in water. At this point, the pH of the absorbent is 8.25 and the pH of the effluent is 8.15, with almost no difference between the two. This means that carbon dioxide has been absorbed by water. It can be seen that the solubility of carbon dioxide in potassium bicarbonate aqueous solution is lower than that in water. Example 3

[0107] The carbon dioxide purification unit was operated in the same manner as in Example 1, except that a 1 M aqueous solution of potassium carbonate was used instead of the absorbent. Figure 8 The measurement results of the carbon dioxide concentration discharged from the carbon dioxide purification unit according to Example 3 are shown. The initial carbon dioxide absorption rate is 99.97%, and carbon dioxide begins to be discharged from the degassing module after about 60 minutes, at which time carbon dioxide absorbed by water is discharged. As the concentration of the absorbent increases, the amount of water decreases due to the reaction of carbon dioxide, and as the operating time of the membrane system increases, the dissolution rate of carbon dioxide decreases. Therefore, it can be seen that a lower concentration of absorbent should be used as much as possible.

[0108] The embodiments and experimental examples of the present invention are described in detail above, but the scope of the present invention is not limited to the above embodiments and experimental examples, and various modifications and improvements of the basic concepts of the present invention as defined in the appended claims by those skilled in the art are also included in the scope of the present invention.

[0109] As is apparent from the above, according to the present invention, it is possible to obtain a hydrogen production and carbon dioxide storage system having a higher carbon dioxide processing capacity than conventional systems.

[0110] According to the present invention, a hydrogen production and carbon dioxide storage system having very low carbon dioxide emissions (below 400 ppm) can be obtained.

[0111] According to the present invention, it is possible to obtain a hydrogen production and carbon dioxide storage system having a larger alkali metal bicarbonate production capacity than conventional systems.

[0112] The effects of the present invention are not limited to the above-mentioned effects. It should be understood that the effects of the present invention include all the effects that can be derived from the above description.

[0113] The present invention has been described in detail with reference to the preferred embodiments of the present invention. However, it will be appreciated by those skilled in the art that these embodiments may be modified without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hydrogen production and carbon dioxide storage system, comprising: A metal-carbon dioxide battery, comprising a negative electrode, a positive electrode and an ion exchange membrane between the negative electrode and the positive electrode; a first supply unit, the first supply unit being configured to provide a first electrolyte to the negative electrode; a second supply unit configured to supply a second electrolyte including hydrogen ions and an alkali metal bicarbonate aqueous solution to the positive electrode; a separation unit configured to separate the product discharged from the positive electrode into hydrogen gas and a circulating liquid; an electrolyte circulation unit, the electrolyte circulation unit being located at the rear end of the separation unit, wherein the electrolyte circulation unit is configured to receive and store the circulating liquid from the separation unit; a dissolution unit, the dissolution unit being located at a rear end of the electrolyte circulation unit, wherein the dissolution unit is configured to dissolve carbon dioxide in a starting material received from the electrolyte circulation unit to produce an electrolyte precursor solution; as well as A carbon dioxide purification unit is configured to purify carbon dioxide from a gas mixture including carbon dioxide supplied from the outside and to supply the carbon dioxide to the dissolving unit.

2. The hydrogen production and carbon dioxide storage system according to claim 1 further comprises a filtration unit located between the second supply unit and the dissolution unit, wherein the filtration unit is configured to precipitate and separate alkali metal bicarbonate from the electrolyte precursor solution received from the dissolution unit to produce the second electrolyte and provide the second electrolyte to the second supply unit. 3 . The hydrogen production and carbon dioxide storage system according to claim 1 , wherein the negative electrode comprises at least one selected from the group consisting of aluminum, zinc, and combinations thereof.

4. The hydrogen production and carbon dioxide storage system according to claim 1, wherein the positive electrode comprises at least one selected from the group consisting of carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal film and a combination thereof; or comprises a catalyst metal supported on a carrier.

5. The hydrogen production and carbon dioxide storage system of claim 1, wherein the ion exchange membrane comprises a cation conductive resin. 6 . The hydrogen production and carbon dioxide storage system according to claim 1 , wherein the first electrolyte comprises at least one selected from the group consisting of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a combination thereof. 7 . The hydrogen production and carbon dioxide storage system according to claim 1 , wherein the second electrolyte has a pH of 7 to 9.

8. The hydrogen production and carbon dioxide storage system according to claim 1, wherein the alkali metal bicarbonate aqueous solution comprises at least one selected from the group consisting of a sodium bicarbonate (NaHCO3) aqueous solution, a potassium bicarbonate (KHCO3) aqueous solution, and a combination thereof. 9 . The hydrogen production and carbon dioxide storage system according to claim 1 , wherein the concentration of the alkali metal bicarbonate aqueous solution in the second electrolyte is in the range of 0.5M to 2M.

10. The hydrogen production and carbon dioxide storage system according to claim 1, wherein the carbon dioxide purification unit comprises: an absorbent storage module configured to store an absorbent including an aqueous solution of an alkali carbonate; an intake module configured to dissolve carbon dioxide of the gas mixture in an absorbent received from the absorbent storage module to produce a concentrate; a degassing module configured to degas carbon dioxide from the concentrate received by the intake module and provide the carbon dioxide to the dissolution unit; as well as An effluent distribution module is configured to receive the effluent discharged from the degassing module, provide a portion of the effluent to the electrolyte circulation unit, and provide the remaining effluent to the absorbent storage module.

11. The hydrogen production and carbon dioxide storage system according to claim 10, wherein the alkali metal carbonate aqueous solution comprises at least one selected from the group consisting of a sodium carbonate (Na2CO3) aqueous solution, a potassium carbonate (K2CO3) aqueous solution, and a combination thereof.

12. The hydrogen production and carbon dioxide storage system according to claim 10, wherein the concentration of the alkali metal carbonate aqueous solution in the absorbent is in the range of 0.01M to 1M.

13. The hydrogen production and carbon dioxide storage system of claim 10, wherein the gas mixture comprises at least one selected from the group consisting of steel by-product gas, exhaust gas, and combinations thereof.

14. The hydrogen production and carbon dioxide storage system according to claim 10, wherein: The air intake module includes an air intake diaphragm configured to separate an inner space of the air intake module into an absorbent flow space and a gas mixture flow space; and Carbon dioxide included in the gas mixture flowing in the gas mixture flow space passes through the gas inlet membrane and is dissolved in the absorbent flowing in the absorbent flow space. 15 . The hydrogen production and carbon dioxide storage system according to claim 10 , wherein a ratio of a flow rate of the absorbent to a gas mixture provided to the air intake module is 1:0.001 to 1:

5. 16 . The hydrogen production and carbon dioxide storage system according to claim 10 , wherein a ratio of the pressure of the absorbent to the gas mixture provided to the intake module is 1:0.1 to 1:

3. 17 . The hydrogen production and carbon dioxide storage system according to claim 10 , wherein the amount of carbon dioxide in the residual gas exhausted from the intake module is 0.1 wt % or less.

18. The hydrogen production and carbon dioxide storage system according to claim 10, wherein: The degassing module includes a degassing membrane configured to separate an inner space of the degassing module into a concentrate flow space and a carbon dioxide degassing space; and Carbon dioxide included in the concentrate flowing in the concentrate flow space passes through the degassing membrane and is discharged to the carbon dioxide degassing space.

19. The hydrogen production and carbon dioxide storage system according to claim 10, wherein the carbon dioxide exhausted from the degassing module has a purity of 99.9% by volume or more.

20. The hydrogen production and carbon dioxide storage system according to claim 10, wherein The effluent distribution module provides part of the effluent to the electrolyte circulation unit, and In the electrolyte circulation unit, the part of the effluent is mixed with the circulating liquid and stored as a starting material.

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