WO2017213413A1

WO2017213413A1 - Carbon dioxide separation method and carbon dioxide separation system

Info

Publication number: WO2017213413A1
Application number: PCT/KR2017/005904
Authority: WO
Inventors: 한종인; 정재인; 정욱; 이예린
Original assignee: 한국과학기술원
Priority date: 2016-06-07
Filing date: 2017-06-07
Publication date: 2017-12-14
Also published as: KR20170138364A

Abstract

The present invention relates to a method and system capable of selectively separating carbon dioxide from industrial waste gas or the like on the basis of an electrochemical system. The use of the method and system for separating carbon dioxide can efficiently separate, with minimum energy, high-purity concentrated carbon dioxide from a mixed gas.

Description

【Specification】

[Name of invention]

CO2 Separation Method and CO2 Separation System

Technical Field

The present invention relates to a method and system capable of selectively separating carbon dioxide from industrial waste gases and the like.

Background Art

Carbon dioxide (C0 ₂ ) is known as a representative greenhouse gas causing global warming, and has recently been reported as a material that adversely affects the ecosystem by causing acidification of seawater and rainwater. It is also known to cause respiratory disease and asphyxiation when the concentration of carbon dioxide in the atmosphere exceeds the reference value (0.038% v / v). Therefore, countries around the world are aware of the problems that occur when the concentration of carbon dioxide in the atmosphere exceeds the threshold and specify as a joint obligation to reduce the emissions of carbon dioxide. Beginning with the Vienna Convention in 1985, the CO2 emissions were restricted by country through the Montreal Protocol (1987), the Climate Change Convention (1992), the Kyoto Protocol (1997), and the Paris Agreement (2015). I try to reduce.

Carbon dioxide is a gas produced in large quantities in the combustion process of fossil fuels such as coal and oil. Due to the positive correlation between fossil fuel use and GDP, population growth and industrial development have accelerated the generation of carbon dioxide and are still increasing. Currently, 80 million tons of carbon dioxide is generated annually.

Generally, about 8 to 15% of carbon dioxide is contained in the exhaust gas based on fossil fuels. Accordingly, Carbon Capture Ut il izat ion and Storage (CCUS) technology, which combines Carbon Capture and Storage (CCS), which captures and stores carbon dioxide, and Carbon Capture and Ut izat ion (CCU), which captures and recycles carbon dioxide. This is getting attention.

CCUS technology encompasses all technologies for selectively separating, transporting, storing and utilizing carbon dioxide in exhaust gases. Ecus is currently commercialized Since the process incremental capture stage accounts for 50 to 의 of the total cost, a low-cost and efficient collection method is needed to reduce the processing cost.

There are currently three ways to separate and capture carbon dioxide. These three methods are pre combust ion, post-combust ion and oxy-fuel combust ion methods. Post-combustion capture is a method of separating carbon dioxide from a mixed gas generated after fuel combustion, and pre-combustion capture is a method of separating carbon dioxide from a mixed gas of carbon dioxide and hydrogen in fuel through oxygen. It is a method of separating carbon dioxide with water through high concentration of oxygen. Each collection method is based on the conversion of carbon dioxide into the gas form after absorption, adsorption, and separation by membrane. Different separation methods are applied according to the type of fuel demand. Among the separation methods, absorption is the most effective method, and the carbon dioxide in the exhaust gas is selectively collected through chemical bonding with carbon dioxide using an amine-based material as an absorbent. However, carbon dioxide ionized by chemical bonds has a disadvantage in that it is difficult to reverse the gas form to be easily recycled, and an additional step is required to recycle the used absorbent.

[Contents of the Invention]

[Problem to solve]

The present invention is to provide a method and system capable of selectively separating carbon dioxide from industrial waste gas and the like.

[Measures of problem]

According to one embodiment of the invention, the anode; cathode; An ion exchange membrane positioned between the anode and the cathode; And a method of separating carbon dioxide using a device including a pair of anode compartments and cathode compartments separated by the ion exchange membrane, wherein a mixed gas including carbon dioxide in a cathode compartment in which hydroxide ions are generated when a voltage is applied to the anode and the cathode A first step of capturing carbon dioxide within to produce carbonic acid-based silver or salts thereof; And moving the carbonate-based ions or salts thereof from the cathode compartment to the anode compartment where hydrogen ions are generated when voltage is applied to the anode and cathode. A method of separating carbon dioxide is provided that includes a second step of reconversion.

According to another embodiment of the invention, the carbon dioxide separation system in a mixed gas containing carbon dioxide, the anode (anode); Cathode; A cathode compartment in which hydroxide ions are generated when a voltage is applied to the anode and the cathode, and carbon dioxide is trapped in a mixed gas including carbon dioxide to generate carbonic acid-based ions or salts thereof; An anode compartment for generating hydrogen ions when a voltage is applied to the anode and the cathode and reconverting the carbonate-based ions or salts thereof transferred to the carbon dioxide; And an ion exchange membrane separating the anode compartment and the cathode compartment.

According to another embodiment of the invention, the first electrode; Second electrode; The above

A cation exchange membrane positioned between the first electrode and the second electrode; And a pair of first and second compartments separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side. In order to generate carbonic acid-based ions or salts thereof by applying a voltage such that the first electrode becomes an anode and the second electrode becomes a cathode, carbon dioxide in a mixed gas containing carbon dioxide is collected in a second section in which hydroxide ions are generated. Stage 1 ; And converting the carbonate-based ions or salts thereof into carbon dioxide in a second section in which hydrogen ions are generated by applying a voltage such that the first electrode becomes a cathode and the second electrode becomes an anode.

There is provided a method for separating carbon dioxide comprising two steps.

According to another embodiment of the invention, the carbon dioxide separation system in a mixed gas containing carbon dioxide, the first electrode; Second electrode; A cation exchange membrane positioned between the first and second electrodes; A pair of crabs 1 and a second compartment separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side; And a power supply for applying a voltage such that the first electrode becomes the anode and the second electrode becomes the cathode, and then applies the voltage such that the first electrode becomes the cathode and the second electrode becomes the anode. A system is provided.

【Effects of the Invention】 By using the carbon dioxide separation method and the carbon dioxide separation system according to an embodiment of the present invention, it is possible to selectively separate carbon dioxide from industrial waste gas at low energy. Accordingly, carbon dioxide, which is a representative greenhouse gas, can be removed economically and efficiently. In addition, according to the method and system, it is expected to provide carbon dioxide useful in a field requiring ultra high purity carbon dioxide, for example, chemical reaction process, by providing concentrated carbon dioxide with high purity.

【Brief Description of Drawings】

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing an electrolysis apparatus including a pair of anode compartments and cathode compartments separated by one ion exchange membrane.

FIG. 2 is a diagram schematically illustrating an electrolysis apparatus including a pair of anode compartments, an intermediate compartment and a cathode compartment separated by two ion exchange membranes. 3 is a diagram schematically illustrating an electrolysis apparatus including two pairs of anode and cathode sections, including one bipolar membrane.

FIG. 4 is a diagram schematically showing an electrolysis device including two bipolar membranes and three pairs of anode compartments and cathode compartments.

5 and 6 are diagrams schematically showing an electrolysis apparatus including four or more bipolar membranes and five or more anode and cathode compartments, and FIG. 5 is a carbonate-based black containing a salt thereof. 6 is a view showing the movement to the anode compartment paired with the cathode compartment, Figure 6 is a view showing the movement of the carbonic acid-based ions or salts thereof to the anode compartment not paired with the cathode compartment including the same.

7 is a view showing a method for implementing a method of separating carbon dioxide using two electrolysis devices.

8 is a view showing a method for implementing a method of separating carbon dioxide using three or more electrolysis devices.

FIG. 9 is a schematic view of the first stage (10) and the second stage (20) using an electrolysis device comprising a pair of first and second compartments separated by a bilateral exchange membrane. .

10 shows a pair of first and second compartments separated by a cation exchange membrane. Figure 1 schematically shows the state (10) of the first step, the state (20) of the second step and the state (10 ') of the first step after the second step using an electrolysis device comprising.

FIG. 11 is a view schematically showing a first stage view 10 and a second stage view 20 using an electrolysis device including two pairs of first and second compartments, including one bipolar membrane. .

12 is a diagram schematically illustrating an electrolysis apparatus including five pairs of first and second compartments, including four bipolar membranes.

FIG. 13 is a graph showing pH over time of the cathode compartment in separating carbon dioxide according to Examples 1 and 2. FIG.

FIG. 14 is a graph showing pH over time of the anode compartment in separating carbon dioxide according to Examples 1 and 2. FIG.

15 is a graph showing the content of pure carbon dioxide (pure C0 ₂ ), the content of H ₂ S0 ₄ and the pH of the positive electrode compartment obtained in the positive electrode compartment of Example 1. FIG. FIG. 16 shows the first and second electrodes in Example 1 2. When the voltage of 5 V and 3 is applied, it is a graph showing the change of concentration of inorganic carbon in the second compartment with time.

[Specific contents to carry out invention]

Hereinafter, a method of separating carbon dioxide and a carbon dioxide separation system according to a specific embodiment of the present invention will be described.

According to one embodiment of the invention, the anode; cathode; An ion exchange membrane positioned between the anode and the cathode; And a method of separating carbon dioxide using a device including a pair of anode compartments and cathode compartments separated by the ion exchange membrane, wherein a mixed gas including carbon dioxide in a cathode compartment in which hydroxide ions are generated when a voltage is applied to the anode and the cathode A first step of capturing carbon dioxide within to produce carbonic acid-based ions or salts thereof; And a second step of transferring the carbonate-based ions or salts thereof from the cathode compartment to the anode compartment where hydrogen ions are generated when voltage is applied to the anode and the cathode, and converting the carbonate-based ions or salts thereof into carbon dioxide. A separation method of is provided. Carbon dioxide separation method according to the embodiment is an electrochemical system Based on the low energy, carbon dioxide can be selectively separated from industrial waste gas. Accordingly, the carbon dioxide separation method can provide an economical CCUS technology by replacing the capture process that occupies 50 to 70% of the total cost of the existing carbon capture technology (CCUS) technology, thereby Carbon dioxide, a representative greenhouse gas, can be efficiently removed from industrial waste gas.

Separation method of carbon dioxide according to the embodiment may provide a high purity concentrated carbon dioxide. Therefore, the method of separating carbon dioxide according to the embodiment is expected to provide carbon dioxide useful in fields requiring ultra-high purity carbon dioxide, for example, chemical reaction processes in which carbon dioxide is used as a precursor.

In addition, the method for separating carbon dioxide according to the embodiment uses a hydroxide ion generated by electrolysis of water instead of an amine-based collector or ammonia, which is a representative collector for carbon dioxide, so that it is regenerated to recycle the collector after carbon dioxide capture. The advantage is that no separate process is required.

Hereinafter, a method of separating carbon dioxide according to the embodiment will be described in detail with reference to FIG. 1.

Referring to Figure 1, the carbon dioxide separation method is an anode (anode); Cathode; An ion exchange membrane (I EM) positioned between the anode and the cathode; And a pair of anode compartments (AC) and cathode compartments (CC) separated by the ion exchange membrane. In the present specification, the device may be referred to as an electrolysis device.

When voltage is applied to the anode and the cathode in the electrolysis device, an oxidation reaction may occur in the anode compartment and a reduction reaction may occur in the cathode compartment. Accordingly, the 'anode' may be referred to as an 'oxide electrode' and the 'cathode' may be referred to as a 'reduction electrode'.

When voltage is applied to the anode and the cathode, hydrogen silver may be generated in the anode compartment, and hydroxide ions may be generated in the cathode compartment. For example, if an anode is installed in the anode compartment, hydrogen ions may be generated due to an oxidation reaction as shown in Equation 1 or 2 below.

[Equation 1]

2H ₂ 0 → 4H ⁺ + 0 ₂ + 4e ^"

[Equation 2]

¾ → 2H ⁺ + 2e 一

In addition, if the negative electrode is installed in the negative electrode compartment, hydroxide ions may be generated due to the reduction reaction as shown in Equation 3 below.

[Equation 3]

2¾0 + 2 & → 20H ^" +

As another example, as described below, if the electrolysis apparatus includes a bipolar membrane (see FIGS. 3 to 6), at least one anode compartment and the cathode compartment may be in contact with the bipolar membrane. When voltage is applied to the anode and the cathode, water is separated into hydrogen ions and silver hydroxide by the bipolar membrane. The hydrogen ions and the hydroxide ions are moved by the electrical attraction, so that hydrogen ions are supplied to the anode compartment in contact with the bipolar membrane and hydroxide ions are supplied to the cathode compartment in contact with the bipolar membrane.

Therefore, a region where hydrogen ions are generated by applying voltage to the anode and the cathode is defined as a cathode compartment, and a region where hydroxide ions are generated is defined as a cathode compartment.

For stable operation of the electrolysis device, high capture efficiency and reconversion efficiency of carbon dioxide, the anode compartment and the cathode compartment may be filled with a solvent in which the electrolyte is dissolved. The solvent may be water, and the electrolyte may be various salts that can be dissolved in water and dissociated into cations and anions. Non-limiting examples of electrolytes include hydrochloride, sulfate, nitrate, carbonate, hydroxide, oxide black. More specifically, the electrolyte is sodium chloride, potassium chloride, lithium chloride, rubidium chloride _: , calcium chloride, magnesium chloride, sodium sulfate, potassium sulfate, lithium sulfate, rubidium sulfate _: , calcium sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, Lithium nitrate, rubidium nitrate, calcium nitrate, magnesium nitrate, sodium carbonate, potassium carbonate, lithium carbonate, rubidium carbonate _: Calcium carbonate, magnesium carbonate, Sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, calcium hydroxide, magnesium hydroxide, sodium potassium oxide, lithium oxide, rubidium oxide, calcium oxide, magnesium oxide, aluminum oxide, or a combination thereof.

In the separation method of carbon dioxide, a voltage may be applied to the anode and the cathode such that hydrogen ions are generated in the anode compartment and hydroxide ions are generated in the cathode compartment. The applied voltage may be adjusted according to the type and concentration of the electrolyte contained in the positive electrode compartment and the negative electrode compartment, the type of oxidation reaction occurring in the positive electrode compartment, the type of reduction reaction occurring in the black negative electrode compartment, and the like. Specifically, the positive electrode and the negative electrode are 0.42 V or more, 0.83 V or more, 1.03 V or more, black is 2.06 V or more, 10 V or less, 7 V or less, 5 V or less, 4 V or less, 3 V or less, and black is 2 V or less. The voltage of can be applied. Within this range, carbon dioxide in the mixed gas can be efficiently separated with little energy.

According to the separation method of carbon dioxide of the embodiment, the mixed gas may be directly supplied to the negative electrode compartment to collect carbon dioxide in the mixed gas in the negative electrode compartment. Accordingly, the method of separating carbon dioxide has the advantage that it is not necessary to provide a separate collecting device such as a scrubber to collect carbon dioxide in the mixed gas.

The mixed gas may be supplied to the cathode compartment before the voltage is applied to the anode and the cathode, at the same time as the voltage is applied to the anode and the cathode, and after the voltage is applied to the black anode and the cathode.

As an example, the mixed gas may be supplied to a cathode compartment after applying a voltage to the anode and the cathode to generate hydroxide ions in abundance. Specifically, the mixed gas has a pH of the cathode compartment of about 10 to 14, about 11 to 14, about 12 to 14, about 13 to 14, and about 10 as the hydroxide ions are generated by applying voltage to the anode and the cathode. To 13, about 11 to 13, about 12 to 13, about 10 to 12, about 11 to 12, or about 10 to 11, may be supplied to the cathode compartment. By supplying the mixed gas to the cathode compartment having such a pH, it is possible to improve the collection efficiency of carbon dioxide in the mixed gas. The mixed gas may be continuously supplied to the cathode compartment or black may be periodically supplied. For example, the mixed gas has a pH of the cathode compartment It may be supplied periodically when the above range is reached.

The carbon dioxide separation method is capable of separating pure carbon dioxide from various mixed gases containing carbon dioxide. Examples of such a mixed gas include a mixed gas requiring separation of carbon dioxide, industrial waste gas discharged from a natural gas power generation facility, a cement refining plant, and an exhaust gas discharged from a combustion process of fuel.

The ratio of carbon dioxide in the mixed gas is not particularly limited, but at least 2% by volume, at least 5% by volume, at least 10% by volume, at least 15% by volume, at least 20% by volume, at least 30% by volume, at least 40% by volume, It may be at least 50% by volume. In this range, more pure and concentrated carbon dioxide can be obtained. On the other hand, the upper limit of the ratio of carbon dioxide contained in the mixed gas is not particularly limited, 100 vol% or less, 90 vol% or less, 80 vol% or less, 70 vol% or less, 60 vol% or less 50 vol% or less, 40 vol% Or less, 30 volume% or less, black may be 20 volume% or less.

The cathode compartment is a region where hydroxide ions are generated when a voltage is applied to the anode and the cathode. Therefore, in the first step, carbon dioxide in the mixed gas supplied to the cathode compartment may be collected as hydroxide ions present in the cathode compartment according to Equation 4 below.

[Equation 4]

C0 ₂ + OH ^" → HC0 ₃ ^"

In the method for separating carbon dioxide according to the embodiment, carbon dioxide in the mixed gas may be collected under normal pressure. Atmospheric pressure means natural pressure that is not pressurized or depressurized. Specifically, the carbon dioxide in the mixed gas may be collected in a pressure range of about 100. 0 to 100. 102 MPa. In addition, the carbon dioxide in the mixed gas in the method for producing carbon dioxide according to the embodiment may be collected at a temperature of about 15 to 80 ^° C black or about 15 to 60 ^° C. As a result, the industrial waste gas black can be supplied directly to the cathode compartment without notice of a mixed gas such as exhaust gas, and carbon dioxide can be collected from the mixed gas.

The pH of the cathode compartment in which carbon dioxide is collected in the mixed gas is about 4 Or more, about 5 or more, about 6 or more, about 7 or more, about 8 or more, about 9 or more, about 10 or more, about 11 or more, or about 12 or more, about 14 or less, about 13 or less, and black may be about 12 or less. . Among them, the pH of the cathode compartment is about 10 to 14, about 11 to 14, about 12 to 14, about 13 to 14, about 10 to 13, about 11 to 13, about 12 to 13, and about 10 for the selective collection of carbon dioxide. 12 to 12, about 11 to 12 black may be adjusted to about 10 to 11.

Meanwhile, carbon dioxide in the mixed gas is selectively collected by hydroxide ions to generate hydrogen carbonate ions (HC0 ₃ _). The hydrogen carbonate (HCCV) is changed to carbonate (C0 ₃ ² ) as the pH is higher. Accordingly, carbon dioxide in the mixed gas supplied to the cathode compartment may be collected by hydroxide ions to generate hydrogen carbonate ions and / or carbonate ions. In this specification, the term 'carbonate-based ion' is used to collectively refer to a mixture of hydrogen carbonate ions, black hydrogen carbonate ions, and carbonate ions.

In addition, if carbon dioxide is continuously collected in the cathode compartment, the concentration of carbonate ions in the cathode compartment increases, and some carbonate ions may bind to the cations dissociated in the electrolyte and precipitate as salts. Therefore, when a voltage is applied to the anode and the cathode and a mixed gas is supplied to the cathode compartment in which hydroxide ions are generated, carbon dioxide in the mixed gas is trapped to form carbonate ions, black carbonate ions and salts thereof, and salts of black carbonate ions. Can be generated.

In order to improve the collection efficiency of carbon dioxide, the negative electrode compartment may include a carbonate, hydroxide black or a combination thereof among the above-mentioned electrolytes. More specifically, the negative electrode compartment includes electrolytes such as sodium carbonate, potassium carbonate, lithium carbonate, rubidium carbonate, calcium carbonate, magnesium carbonate, sodium hydroxide, potassium hydroxide lithium hydroxide, rubidium hydroxide, calcium hydroxide, and magnesium hydroxide black. can do.

The carbonate supplied as an electrolyte to the cathode compartment is dissociated into cations and silver carbonate (C0 ₃ ² ), and the carbonate ions may collect carbon dioxide in a mixed gas to generate hydrogen carbonate ions as shown in Equation 5 below.

[Equation 5]

C0 ₂ + C0 ₃ ² — + ¾0 → 2HC0 ₃ ^" In addition, the hydroxide supplied as an electrolyte to the cathode compartment is also dissociated into cations and hydroxide ions, and the hydroxide ions may collect carbon dioxide in a mixed gas as in Formula 4 to generate hydrogen carbonate ions.

In this way, the carbonate and hydroxide black supplied as electrolyte to the cathode compartment can stably capture carbon dioxide in the initial mixed gas. In addition, carbon dioxide in the mixed gas may be continuously collected by the hydroxide ions generated by applying voltage to the anode and the cathode.

Carbonate ions dissociated from the carbonate supplied to the electrolyte and hydroxide ions dissociated from the hydroxide supplied to the electrolyte or generated by applying voltage to the black anode and cathode have the advantage of selectively trapping carbon dioxide in the mixed gas, and then into carbon dioxide. In the second stage of reconversion, there is an advantage that carbon dioxide can be regenerated without a separate energy supply. The concentration of carbonates, hydroxide blacks, and mixtures thereof supplied to the electrolyte may be appropriately adjusted in consideration of carbon dioxide capture efficiency and economic efficiency. Specifically, the electrolyte may be supplied to the negative electrode compartment at a concentration below the saturation concentration of the electrolyte, and more specifically, the electrolyte is 1% to 50%, 1% to 30% black silver 22% to 28% relative to the saturation concentration Can be supplied. In one example, the saturated concentration of sodium carbonate at 15 ^° C is 1.55 M. Therefore, in the case of using sodium carbonate as the electrolyte, sodium carbonate may be supplied so that the concentration of sodium carbonate in the negative electrode compartment is 0.0155 to 0.775 M, 0.0155 to 0.465 M, or 0.341 to 0.434 M based on 15 ^° C. Within this range, carbon dioxide can be captured economically and efficiently.

When carbon dioxide is collected in the first step to sufficiently generate carbonate-based ions or salts thereof, the carbonate-based silver or salts thereof may be moved from the cathode compartment to the anode compartment.

The time point when carbon dioxide is collected and the carbonic acid-based salts or salts thereof are generated can be confirmed by the pH of the anode compartment or the cathode compartment, the concentration of carbonate ions in the electrolyte of the cathode compartment, the electrical conductivity of the black cathode compartment, and the like. For example, when a voltage is applied to the anode and the cathode, hydroxide ions are generated in the cathode compartment, so that the cathode compartment exhibits a high pH, or black is the above. Carbonate, hydroxide black, or a mixture thereof is supplied to the cathode compartment as an electrolyte so that the cathode compartment can exhibit high pH. However, since the silver hydroxide and carbonate ions are used to capture carbon dioxide as in Equation 4 and Equation 5, as the carbon dioxide is collected, the pH of the cathode compartment is gradually lowered. As a result of the experiments of the inventors, the pH of the cathode compartment is gradually lowered as the carbon dioxide is collected so that a constant value between about 7 to 9, about 7 to 8. 5 black and about 7. 5 to 8. 5 is maintained. It was confirmed. It can be seen that the reaction of the cathode compartment has reached equilibrium from the fact that the pH of the cathode compartment is maintained at a constant value. Thus, if the pH of the negative electrode compartment maintains a constant value between about 7 and 9, the carbonate-based ions or salts thereof in the negative electrode compartment can be transferred to the positive electrode compartment.

As another example, while carbon dioxide is collected in the cathode compartment, hydrogen ions are continuously generated in the anode compartment, thereby lowering the pH of the anode compartment. Therefore, when the pH of the anode compartment is 0 to 3, 1 to 3, 2 to 3, 0 to 2, 1 to 2 black is 0 to 1, the carbonate-based ions or salts thereof in the cathode compartment are moved to the anode compartment. Can be.

In another example, when the concentration of carbonate ions in the cathode compartment is measured directly or indirectly, if the carbonate ions are produced above the saturation concentration, for example, above the saturation concentration, the carbonate ions or salts thereof are added to the cathode compartment. Can be moved to the anode compartment.

As another example, as the carbon dioxide is collected in the cathode compartment, the concentration of carbonic acid ions increases to increase the electrical conductivity of the cathode compartment. Therefore, the electrical conductivity of the cathode compartment is measured to increase the electrical conductivity from 0 mS / cm to 50 mS / cm, 10 mS / cm to 50 mS / cm, 20 mS / cm to 50 mS / cm, and 30 mS / cm to When 50 mS / cm, black is 40 mS / cm to 50 mS / cm, carbonate-based ions or salts thereof can be moved from the cathode compartment to the anode compartment.

The method for transferring the carbonate-based ions or salts thereof into the anode compartment is not particularly limited, and the electrolyte solution contained in the cathode compartment may be anode by using a method of supplying an electrolyte solution or the like from the reservoir to the cathode compartment or the anode compartment. Can be moved to a compartment Accordingly, carbonic acid ions Alternatively, a moving path and a fluid flow rate regulating device may be installed between the cathode compartment in which the salt thereof is formed and the anode compartment in which the carbonate-based ion or the salt thereof is supplied.

Whenever the concentration of carbonate-based ions or salts thereof generated in the cathode compartment is above a certain level, the carbonate-based ions or salts thereof in the cathode compartment may be periodically moved to the anode compartment.

The content of the carbonate-based ions or salts thereof transferred to the anode compartment may be adjusted according to the amount of carbon dioxide to be obtained in the anode compartment.

Carbonic acid ions or salts thereof supplied from the cathode compartment are reconverted to carbon dioxide in the anode compartment. Specifically, the anode compartment is a region in which hydrogen is generated when a voltage is applied to the anode and the cathode, and when a carbonate-based ion or a salt thereof is supplied to the anode compartment, according to the equation of pH equilibrium as shown in Equations 6 and 7 below. Can be converted to carbon dioxide. Specifically, the carbonate dissociated from the carbonate or black carbonate dissolved in the electrolyte may be converted to hydrogen carbonate ions as shown in Equation 6 below, and the hydrogen carbonate ions may be converted to carbon dioxide as shown in Equation 7 below.

[Equation 6]

C0 ₃ ^{2 "} + H ⁺ → HC (

[Equation 7]

HC0 ₃ ^" + H ⁺ → C0 ₂ + H ₂ 0

In particular, in the method for separating carbon dioxide according to the embodiment, since carbonate black or black hydroxide ions are used as the trapping agent, the collected carbon dioxide may be reconverted into carbon dioxide without adding an additive or supplying energy.

In the second step, carbonic acid-based ions or salts thereof may be converted into carbon dioxide under normal pressure. Specifically, the carbonate-based ions or salts thereof may be reconverted to carbon dioxide at a pressure in the range of about 0.1 to 100 MPa.

In the second step, the carbonate-based ions or salts thereof may be reconverted to carbon dioxide at a temperature of about 15 to 80 ^° C. black or about 15 to 60 ^° C. Accordingly, even if the industrial waste gas black or the mixed gas such as the exhaust gas is used immediately without notice, carbon dioxide can be separated from the mixed gas with excellent efficiency.

The pH of the anode compartment in which the carbonic acid ion or salt thereof is reconverted to carbon dioxide may be about 7 or less, about 6 or less, about 5 or less, about 4 or less, about 3 or less, and black may be about 2 or less, about 0 or more, or about One or more blacks may be about two or more. Among them, the pH of the anode compartment is about 0 to 6, about 0 to 5, about 0 to 4, about 0 to 3, about 0 to 2, about 0 to 1, about 1 to 6, for efficient reconversion to carbon dioxide. About 1 to 5, about 1 to 4, about 1 to 3, about 2 to 6, about 2 to 5, about 2 to 4 black may be adjusted to about 2 to 3.

On the other hand, a lower voltage is required when generating hydrogen ions through the oxidation reaction of hydrogen gas than when generating hydrogen ions through oxidation reaction of water. In the cathode compartment, hydrogen gas is generated according to Equation 3, and the hydrogen gas is moved from the cathode compartment to the anode compartment to save more energy.

Specifically, when the carbonic acid-based ions or salts thereof are converted into carbon dioxide by hydrogen ions generated through oxidation reaction of hydrogen gas in the second step, a voltage of 0.83 V to 2 V is applied to the anode and the cathode. Can be authorized. Applying a voltage in this range can significantly reduce the energy required to separate carbon dioxide. In addition, the theoretical voltage for oxidizing water to generate hydrogen ions and oxygen gas is 2.06V. Therefore, the purity of carbon dioxide can be improved by suppressing generation of oxygen gas in the anode compartment by adjusting the voltage range as described above.

On the other hand, as the ratio of carbon dioxide in the mixed gas increases, the collection efficiency of carbon dioxide in the first stage may be improved, and the purity and yield of carbon dioxide obtained through the second stage may be improved. Accordingly, the method of separating carbon dioxide according to the embodiment may pretreat the mixed gas before the first step.

For example, before the mixed gas is supplied to the cathode compartment, the mixed gas may be contacted with a solvent to remove other gases other than carbon dioxide from the mixed gas. In the case of using the above-described industrial waste gas as the mixed gas, the mixed gas may include gases such as S0 _X) HF, HC1, NH ₃ , Cl ₂ , SiF ₄₎ 0 ₂ , N ₂ , CO, N0 _X , SH _{2 in} addition to carbon dioxide. It may include.

C¾ may be a pH of 3.5 to 5.5 which is not very soluble in _{water, S0 X, HF, HC1,} NH 3, Cl 2, SiF 4 and so on is smoothly dissolved. Thus, the heunhap gas a pH in water of about 3.5 to 7, 3.5 to 6, from about 3.5 to 5.5, the pH range than C0 ₂ from the gas mixture about 3.5 to 5 black is brought into contact with from about 3.5 to 4 water A gas with high solubility in water, for example, S0 _X , HF, HC1, N¾, Cl ₂₎ SiF _4, etc., can be removed in advance.

Specifically, the mixed gas is passed through a container, a black tube, or the like, containing the water in the pH range, or the black is sprayed with the water in the pH range to the flow of the mixed gas passes in advance to other gases other than ω ₂ in the mixed gas in advance. Can be removed

For example, the pretreatment of the mixed gas may be performed using a scrubber. Specifically, the pretreated mixed gas may be obtained by filling the scrubber with water in the pH range and dispersing the mixed gas under a high pressure through a sparger. In addition, after the mixed gas is supplied to the scrubber inlet, water of the pH range may be injected into the flow of the mixed gas to obtain a pretreated mixed gas from the outlet of the scrubber.

In addition, gases other than C0 ₂ not removed in this pretreatment step may not be dissolved in the high pH electrolyte in the cathode compartment and may be removed naturally. Specifically, the gas such as 0 ₂ , N ₂ , CO, N0 _X , SH _{2 in} the mixed gas does not dissolve in the high pH electrolyte of the cathode compartment, and thus the mixed gas containing such gas is supplied from the mixed gas even if the mixed gas containing the gas is supplied to the cathode compartment. You can optionally collect C0 ₂ . On the other hand, the inventors have found that after a lot of research, when the mixed gas contains C0 ₂ and S0 ₂ , SO ₂ improves the capture efficiency and reconversion efficiency of CO ₂ . Therefore, if the mixed gas contains ω ₂ and so ₂ , carbon dioxide can be separated from the mixed gas more efficiently even if the pretreatment step is omitted. In addition, sulfate ions (SO ₄ ² —) can be obtained from SO ₂ with the separation of carbon dioxide. Specifically, when the mixed gas is supplied to the cathode compartment as described above, carbon dioxide in the mixed gas is collected by the hydroxide ions present in the cathode compartment as shown in Equation 4 above. In addition, sulfur dioxide in the mixed gas may be collected by hydroxide ions present in the cathode compartment as shown in Equation 8.

[Equation 8]

S0 ₂ + OH ^" → S0 ₃ ² — + H ⁺

In this case, the mixed gas may not be pretreated so that the mixed gas may contain NO _x . However, as described above Ν0 _Χ is not dissolved in an electrolytic solution of high ρΗ the cathode compartment. Thus, Ν0 _Χ can be removed not to enter the melt electrolyte to supply the gas to the cathode compartment heunhap.

If sulfur dioxide is continuously collected by the hydroxide ions as shown in Equation 8, the concentration of sulfite ions (sul ^{fite s0} ₃ ^{2 ᅵ} ) in the cathode compartment is increased, similar to the carbonate ions, and some sulfite ions are electrolytes. It may be precipitated as a salt in combination with a cation derived from and the like. Therefore, when a voltage is applied to the anode and the cathode and a mixed gas is supplied to the cathode compartment in which hydroxide ions are generated, carbon dioxide in the mixed gas is trapped to form carbonate ions, black carbonate ions and salts thereof, and salts of black carbonate ions. And sulfur dioxide in the mixed gas may be collected to form sulfite ions, sulfite ions and salts thereof, and salts of black sulfite ions.

Then, as described above, the sulfite ions or salts thereof along with the carbonate ions or salts thereof are moved from the cathode compartment to the anode compartment to reconvert the carbonate ions or salts thereof to carbon dioxide in the anode compartment and from the sulfite ions or salts thereof. Sulfate ions or salts thereof can be produced. The second step can be carried out as described above, except that the disulfide or sulfite along with the carbonate ions or salts thereof is moved from the cathode compartment to the anode compartment, unless otherwise noted.

The sulfite ions dissociated from the sulfite ions or salts thereof supplied to the anode compartment may react with water to generate hydrogen ions as shown in Equation 9 below.

[Equation 9] S0 ₃ '^" + H ₂ 0 → SO ^" + 2W + 2

Since the carbonate-based ions or salts thereof supplied to the anode compartment are reconverted to carbon dioxide by hydrogen ions, reactions that generate sulfate ions from sulfite ions generating hydrogen ions can promote the reconversion reaction of carbon dioxide. In addition, sulfate ions generated from sulfite ions can improve the electrical conductivity by increasing the total amount of ions in the anode compartment.

On the other hand, when the anode compartment and the cathode compartment are separated by the cation exchange membrane, hydrogen ions may move through the cation exchange membrane by the electrical attraction to the cathode compartment. However, even in this case, when sulfite ions or salts thereof are supplied to the anode compartment, hydrogen ions are additionally generated as shown in Equation 9, so that the carbon dioxide reconversion efficiency may not be reduced.

Meanwhile, in the anode compartment, hydrogen ions and oxygen gas are generated due to the oxidation reaction of water as in Equation 1 above. Accordingly, not only carbon dioxide but also oxygen gas is released from the anode compartment, the purity of carbon dioxide obtained in the anode compartment may be reduced. However, sulfite ions dissociated from the sulfite ions or salts thereof supplied to the anode compartment may consume oxygen gas generated in the anode compartment by reacting with oxygen to generate sulfate ions as shown in Equation 10 below. Accordingly, it is possible to improve the purity of carbon dioxide emitted from the anode compartment.

[Equation 10]

2S¾ ² — + 0 ₂ → 2S0 ₄ ² —

On the other hand, in the anode compartment, hydrogen ions are required to reconvert carbon dioxide from carbonate-based ions or salts thereof, and the hydrogen ions are subjected to oxidation reaction of sulfite ions or salts thereof according to Equation 9 rather than electrolysis of water according to Equation 1 above. If so, it is possible to prevent the generation of oxygen gas in the anode compartment to provide high purity carbon dioxide. Specifically, a voltage of 1.03 V to 2 V may be applied to the anode and the cathode to minimize the oxygen gas generated in the anode compartment. Since the theoretical voltage for oxidizing water to generate hydrogen ions and oxygen gas is 2.06 V, it is possible to suppress the generation of oxygen gas by adjusting the voltage range as described above. have.

On the other hand, the anode compartment may further improve the purity of carbon dioxide by further including a catalyst to promote the reaction of the formula (10). As such a catalyst, any catalyst capable of promoting the reaction of oxidizing sulfite ions (S¾ ² —) to sulfate ions (S0 ₄ ² —) may be used. For example, the catalyst is composed of a compound containing Co ²⁺ , Fe ²⁺ , Fe ³⁺ , Mn ²⁺ , Zn ²⁺ , Au ²⁺ or Cu ²⁺ and a compound containing Au, kg, Ru or Ir It may be one or more compounds selected from the group.

When the catalyst is included in the anode compartment, a voltage optimized for capture and reconversion of carbon dioxide may be applied to the anode and the cathode regardless of generation of oxygen gas. Specifically, when a catalyst is included in the anode, a voltage of 0.83 V to 20 V, 0.83 V to 15 V, or 0.83 V to 10 V may be applied to the anode and the cathode.

On the other hand, in the carbon dioxide separation method according to the embodiment may repeat the first step after the second step. Thereby, high purity and high concentration of carbon dioxide can be separated continuously from the mixed gas.

The first and second steps described above may be performed using the electrolysis device described above. Hereinafter, the electrolysis device used in the carbon dioxide separation method according to the embodiment will be described in detail.

Referring to FIG. 1, the electrolysis device includes an anode; Cathode; An ion exchange membrane (IEM) positioned between the anode and the cathode; And a pair of anode compartments (AC) and cathode compartments (CC) separated by the ion exchange membrane.

The ion exchange membrane may be a cat ion exchange membrane (CEM) or an anion exchange membrane (AEM). As described above, carbon dioxide in the mixed gas in the cathode compartment is captured by the hydroxide ions, and carbonic acid-based ions or salts thereof in the anode compartment may be converted back to carbon dioxide by hydrogen ions. If a pair of anode and cathode compartments are separated by an anion exchange membrane, hydroxide ions are passed through the anion exchange membrane by electrical attraction to the anode compartment to reduce the CO 2 capture efficiency. Can be degraded. On the other hand, if a pair of anode and cathode compartments are separated by a cation exchange membrane, hydrogen ions may pass through the cation exchange membrane by electrical attraction to the cathode compartment and the carbon dioxide reconversion efficiency may be lowered. In the case of the anion exchange membrane, only the ion species passing through the negative exchange membrane are hydroxide ions. In the case of the cation exchange membrane, in addition to the hydrogen ions, there are cations dissociated from the electrolyte. In view of this, it can be seen that the degree of reduction in the efficiency of carbon dioxide trapping by the migration of hydroxide ions by the anion exchange membrane is greater than the degree of reduction of the conversion efficiency of carbon dioxide by the movement of hydrogen ions by the cation exchange membrane. In addition, referring to the reaction formula described in the anode compartment AC of FIG. 1, hydrogen ions are supplied in many routes as compared with hydroxide ions. For example, hydrogen ions can be obtained from hydrogen gas supplied from the cathode compartment, and the collection of sulfur dioxide together with carbon dioxide generates additional hydrogen ions with the formation of disulfide sulphate from sulfite ions. Therefore, when the pair of anode and cathode compartments are separated by one ion exchange membrane, a different exchange membrane may be employed as the ion exchange membrane.

When the pair of anode compartments and the cathode compartments are separated by one ion exchange membrane, the separation method of carbon dioxide may further include a step of regenerating the electrolyte after the second step.

Regenerating the electrolyte may be performed by mixing the electrolyte solution in the positive electrode compartment and the negative electrode compartment, and supplying a uniformly mixed electrolyte solution to the positive electrode compartment and the negative electrode compartment.

More specifically, regenerating the electrolyte may be performed by applying a voltage to the positive electrode and the negative electrode to adjust the pH of the positive electrode compartment to 3 to 5, and to adjust the pH of the negative electrode compartment to 11 to 12, the electrolyte solution of the positive electrode compartment and the negative electrode compartment It can be carried out by producing an electrolyte solution of pH 8 to 10 by mixing. The electrolyte of pH 8 to 10 thus produced can be supplied to the positive electrode compartment and the negative electrode compartment again.

Meanwhile, referring to FIG. 2, both a cation exchange membrane (CEM) and an anion exchange membrane (AEM) may be employed as the ion exchange membrane. Specifically, this electrolysis device is intermediate between a pair of anode compartments (AC) and cathode compartments (CC). Anion exchange membrane (AEM) separating the anode compartment (AC) and the intermediate compartment (MC) so that a middle compartment (MC) is present and a cation exchange membrane (CEM) separating the middle compartment (MC) and the cathode compartment (CC) It may include.

In such an electrolysis device, hydrogen ions generated in the anode compartment (AC) are directed toward the cathode compartment (CC) by electrical attraction, but remain in the anode compartment by the anion exchange membrane (AEM), and the hydroxide generated in the cathode compartment (CC). Ions are directed towards the anode compartment (AC) by electrical attraction but stay in the cathode compartment by the cation exchange membrane (CEM). Accordingly, when the pair of anode compartments and the cathode compartments are separated by two ion exchange membranes, the step of regenerating the above-described electrolyte may be omitted.

In addition, the intermediate compartment (MC) may unexpectedly prevent the cation exchange membrane from passing through the cation exchange membrane or the anion exchange membrane from the anode compartment black cathode compartment due to chemical black physical defects of the cation exchange membrane black anion exchange membrane so that the anion does not cross over to the opposite compartment. Play a role

When the voltage on the positive and negative electrodes is the cation present in the intermediate compartment (MC) is moved to the cathode compartment (CC) through the cation exchange membrane _(CEM): the anion is a positive electrode compartment (AC) through an anion exchange membrane (AEM) The electrolyte in the intermediate compartment can be desalted by moving to. Accordingly, the desalination may be supplied to the intermediate compartment MC to desalination. Specifically, the middle compartment may be desalted by supplying water resources including salts such as seawater, sewage, wastewater, and industrial water or their mixtures. Accordingly, by continuously supplying a water resource including a salt to the intermediate compartment as an electrolyte solution to obtain desalted fresh water continuously, it is possible to simultaneously perform a separation process and a desalination process of carbon dioxide.

However, the type of electrolyte supplied to the intermediate compartment is not limited thereto, and artificial brine may be supplied or black artificial brine may be supplied in combination with the water resource. The artificial saline may be a solvent in which the above-described electrolyte is dissolved.

The electrolysis device may include two or more pairs of anode compartments and cathode compartments using a bipolar membrane. When voltage is applied to the positive and negative poles, Water is separated into hydrogen ions and hydroxide ions by a bipolar membrane, and the hydrogen ions and hydroxide ions can be moved by electrical attraction. In the electrolysis device, the bipolar membrane may be replaced with a water migration passage whose sidewall is composed of the bipolar membrane. When water is flowed into the water passage and voltage is applied to the anode and the cathode, the water is separated into hydrogen hydride and hydroxide ions in the bipolar membrane where the water is the sidewall, and hydrogen ions are supplied to the anode compartment by electrical attraction. The compartment may be supplied with hydroxide ions.

Referring to FIG. 3, the electrolysis device includes an anode; Cathode; A bipol membrane (BM) positioned between the anode and the cathode; Two ion exchange membranes IEM positioned between the anode and the bipolar membrane BM and between the bipolar membrane BM and the cathode; Each ear may comprise two pairs of anode compartments AC and cathode compartments CC separated by an exchange membrane IEM. Referring to FIG. 4, the electrolysis device includes an anode; Cathode; Two or more bipolar membranes (BM) positioned between the anode and the cathode; between the anode and the bipolar membrane (BM), between the bipolar membrane and the bipolar membrane, and between the bipolar membrane (BM) and the cathode (cathode) Three or more ion exchange membranes (IEMs) located in the; It may include three or more pairs of anode compartments AC and cathode compartments CC separated by respective ion exchange membranes IEM. 5 and 6 are diagrams schematically showing an electrolysis apparatus including four or more bipolar membranes.

In the electrolysis apparatus including the bipolar membrane, as described above, a region in which a voltage is applied to the anode and a cathode to generate hydroxide ions is a cathode section, and a region in which a voltage is applied to the anode and the cathode to generate hydrogen ions is a cathode section.

When using such an electrolysis device, a mixed gas may be supplied to each of two or more cathode compartments. In addition, the carbonate-based ions or salts thereof generated in each cathode compartment may be moved to the anode compartment paired with the corresponding cathode compartment as shown in FIG. 5, or moved to the anode compartment paired with another cathode compartment as shown in FIG. 6. .

On the other hand, the carbon dioxide separation method according to the embodiment is two or more It can be implemented using an electrolysis device.

Referring to FIG. 7, the carbonate-based ions or salts thereof generated in the cathode compartment of the first electrolysis apparatus 100 are moved to the anode compartment of the second electrolysis apparatus 200 to convert the carbonate-based ions or salts thereof into carbon dioxide. Reconversion, and the carbonate-based ions or salts thereof generated in the cathode compartment of the second electrolysis device 200 are transferred to the anode compartment of the first electrolysis device 100 to reconvert the carbonate-based ions or salts thereof to carbon dioxide. can do. In FIG. 7, each electrolysis device is represented as a device including a pair of anode compartments and a cathode compartment separated by one silver exchange membrane, but each electrolysis unit is represented by two ions schematically shown in FIG. 2. The device may include a pair of anode compartments, an intermediate compartment and a cathode compartment by means of an exchange membrane, or black may be a device including two or more pairs of anode compartments and cathode compartments including the bipolar membrane shown in FIGS. 3 to 6. In addition, referring to FIG. 8, the method for separating carbon dioxide according to one embodiment may be implemented using three or more electrolysis devices.

The electrolysis device may be configured as known in the art. Hereinafter, the components constituting the electrolysis device will be described in detail.

As the cation exchange membrane and the negative exchange membrane, all kinds of ion exchange membranes applied to an electrolysis device or a fuel cell may be used. Specifically, for example, as a cation exchange membrane, commercially available Nafion from Dupont or CMX of Tokuyama, Japan can be used. As an anion exchange membrane, for example, Tokuyama, Japan AMX, AHA, ACS, etc. can be used.

The positive electrode and the negative electrode may be installed at an appropriate position to exert an electrical attraction to the ionic species contained in the positive electrode compartment and the negative electrode compartment. The shape of the positive electrode and the negative electrode is not particularly limited, and may be variously modified as known in the art.

As the anode and the cathode, various kinds of electrodes applied to an electrolysis device or a fuel cell may be used. For example, the anode and As the cathode, various kinds of conductors may be used, or an electrode including an electrode substrate and a catalyst applied to the electrode substrate may be used. The above conductors include titanium (Ti), stainless steel, nickel (Ni), nickel / chromium (Ni / Cr) alloys, platinum (Pt), gold (Au), palladium (Pd), iridium (Ir) and rhodium ( Rh), ruthenium (Ru) or those selected from the group consisting of these oxides can be used. In addition, in an electrode including a catalyst coated on the electrode substrate, carbon cloth or the like may be used as the electrode substrate, and platinum (Pt), ruthenium (Ru), osmium (0s), or palladium may be used as the catalyst. (Pd), iridium (Ir), carbon (other transition metals and mixtures thereof) may be used.

The positive electrode and the negative electrode may be connected to a power supply. As the power supply device, any of those known in the art to which the present invention pertains may be used as long as the voltage can be applied to the positive electrode and the negative electrode. The electrolysis device may include a movement path connecting the anode compartment and the cathode compartment to allow fluid to move between the anode compartment and the cathode compartment. The material forming the moving path is not particularly limited as long as it is not corroded or damaged by the fluid and can withstand the flow of the fluid. For example, the moving path may be formed of various materials such as SUS (steel use stainless), acrylic polymer, Teflon, nylon. In addition, the flow path may be further provided with a fluid flow rate control device.

The electrolysis device may be connected to one or more reservoirs so as to continuously supply a mixed gas and an electrolyte to the electrolysis device, and collect carbon dioxide and fresh water obtained from the electrolysis device.

In addition, the electrolysis device includes a fluid flow rate adjusting device capable of adjusting a flow rate of a fluid or the like; A sensor for monitoring the status of the anode compartment, the cathode compartment, and optionally an intermediate compartment; And a recording device capable of recording an electrical signal related to the electrolysis device and a change in solution properties of each compartment.

The electrolysis device further includes a configuration commonly employed in addition to the above-described configuration, such as an electrolysis device known in the art. Black may be employed as part of a larger facility in connection with other device components.

On the other hand, according to another embodiment of the present invention, the carbon dioxide separation system in a mixed gas containing carbon dioxide, the anode (anode); Cathode; A cathode compartment in which hydroxide ions are generated when a voltage is applied to the anode and the cathode, and carbon dioxide is trapped in a mixed gas including carbon dioxide to generate carbonic acid-based ions or salts thereof; An anode compartment for generating hydrogen ions when a voltage is applied to the anode and the cathode and reconverting the carbonate-based ions or salts thereof transferred to the carbon dioxide; And an ion exchange membrane separating the anode compartment and the cathode compartment.

The carbon dioxide separation system is a system capable of performing the above-described method of separating carbon dioxide, which has been described in detail above, and thus, a detailed description thereof will be omitted.

Since the method for separating carbon dioxide according to one embodiment of the present invention is capable of purely separating carbon dioxide from a mixed gas discharged during combustion, it is expected to be applicable to various technical fields for separating, using, or treating carbon dioxide. In particular, the carbon dioxide separation method is useful for reducing the cost of the ecus technology, it is expected to provide carbon dioxide useful in fields requiring ultra-high purity carbon dioxide, for example, chemical reaction process.

On the other hand, according to another embodiment of the present invention, the first electrode; Second electrode; A cation exchange membrane positioned between the first electrode and the second electrode; And a pair of first and second compartments separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side. The first electrode may be a cathode, and the second electrode may be applied with a voltage to collect carbon dioxide in a mixed gas including carbon dioxide in a second compartment in which hydroxide ions are generated, thereby generating carbonic acid-based silver or a salt thereof. Stage 1; And generating a hydrogen ion by applying a voltage such that the first electrode becomes a cathode and the second electrode becomes an anode. There is provided a method for separating carbon dioxide comprising a second step of reconverting the carbonate-based ions or salts thereof to carbon dioxide in two compartments.

The method for separating carbon dioxide according to the embodiment may selectively separate carbon dioxide from industrial waste gas and the like with low energy based on an electrochemical system. Accordingly, the carbon dioxide separation method can provide an economical CCUS technology by replacing the capture process that occupies 50 to 70% of the total cost of the existing Carbon Capture Ut ion ion and Storage (CCUS) technology, thereby Carbon dioxide, a representative greenhouse gas, can be efficiently removed from industrial waste gas.

Separation method of carbon dioxide according to the embodiment may provide a high purity concentrated carbon dioxide. Therefore, the carbon dioxide separation method according to the embodiment is expected to provide a carbon dioxide useful in the field requiring ultra-high purity carbon dioxide, for example, chemical reaction process using carbon dioxide as a precursor.

In addition, the method for separating carbon dioxide according to the embodiment uses a hydroxide ion generated by electrolysis of water instead of amine-based collector black or ammonia, which is a representative collector for carbon dioxide, so that it is regenerated to recycle the collector after carbon dioxide capture. There is an advantage that no separate process is required.

Hereinafter, a method of separating carbon dioxide according to the embodiment will be described in detail with reference to FIG. 9.

9, the carbon dioxide separation method may include a first electrode (f irst electrode; 1st EL); Second electrode (2nd EL); A cat ion exchange membrane (CEM) positioned between the first electrode and the second electrode; And a pair of first and second compartments separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side. compartment (2nd CP). In the present specification, the device may be referred to as an electrolysis device.

In the first step, the first electrode becomes the anode and the second electrode becomes the cathode. When a voltage is applied, an oxidation reaction may occur in the first compartment located on the first electrode side based on the cation exchange membrane, and a reduction reaction may occur in the second compartment located on the second electrode side based on the cation exchange membrane. That is, in the present specification, 'anode' means 'oxidizing electrode', and 'cathode' means 'reducing electrode'.

In the first step, when a voltage is applied such that the first electrode becomes the anode and the second electrode becomes the cathode, hydrogen ions may be generated in the first compartment, and hydroxide ions may be generated in the second compartment (see FIG. 9 10). .

For example, if the first electrode is installed in the first compartment, hydrogen ions may be generated due to oxidation reaction as shown in Equation 1 or 2 below.

[Equation 1]

2¾0 → 4H ⁺ + 0 ₂ + 4e—

[Equation 2]

¾ → 2H ⁺ + 2e ^"

And, if the second electrode is installed in the second compartment, hydroxide ions may be generated due to the reduction reaction as shown in Equation 3 below.

[Equation 3]

2 0 + 2e— → 20H— +

As another example, if the electrolysis apparatus includes a bipolar membrane as described below (see FIGS. 11 and 12), at least one of the first and second compartments may be in contact with the bipolar membrane. When voltage is applied to the first and second electrodes, water is separated into hydrogen ions and hydroxide ions by the bipolar membrane. The hydrogen ions and the hydroxide ions are moved by electrical attraction. If a voltage is applied to the first and second electrodes such that the first electrode becomes the anode and the second electrode becomes the cathode, hydrogen is added to the first compartment adjacent to the bipolar membrane. Hydrogen ions are supplied to the second compartment in which the ions are supplied and in contact with the bipolar membrane.

On the other hand, when a voltage is applied such that the first electrode becomes the cathode and the second electrode becomes the anode in the second step, the same reaction occurs as in the second section of the first step in the first section, and in the second section, The first stage Reactions, such as I compartments, occur.

For example, if the first electrode is installed in the first compartment and the second electrode is installed in the second compartment, the reduction reaction occurs in the first compartment of the second stage as in Equation 3 to generate hydroxide ions, and In the two compartments, an oxidation reaction may occur as in Equation 1 or Equation 2 to generate hydrogen ions (see 20 in FIG. 9).

As another example, as described above, the electrolysis device includes a bipolar membrane (see FIGS. 11 and 12), and according to the second step, the first electrode and the second electrode become the anode according to the second step. When a voltage is applied to the electrode, hydroxide ions are supplied to the first compartment in contact with the bipolar membrane and hydrogen ions are supplied to the second compartment in contact with the bipolar membrane (Fig.

20 of II).

Accordingly, the type of ions generated in the first and second compartments may be determined depending on which of the first and second electrodes is applied with a voltage such that the anode is the anode black or the cathode.

The first and second compartments may be filled with a solvent in which an electrolyte is dissolved for stable driving of the electrolysis device, high capture efficiency and reconversion efficiency of carbon dioxide. The solvent may be water, and the electrolyte may be various salts that can be dissolved in water and dissociated into cations and anions. By way of non-limiting example, the electrolyte may be a hydrochloride, sulfate, nitrate, carbonate, hydroxide, oxide black or a combination thereof. More specifically, the electrolyte is sodium chloride, lithium chloride, rubidium chloride, calcium chloride, magnesium chloride, sodium sulfate sulfate, lithium sulfate, rubidium sulfate, calcium sulfate, magnesium sulfate, sodium nitrate, potassium nitrate, lithium nitrate, rubidium nitrate, Calcium nitrate, magnesium nitrate, sodium carbonate potassium carbonate, lithium carbonate, rubidium carbonate, calcium carbonate, magnesium carbonate, sodium hydroxide potassium hydroxide, lithium hydroxide, rubidium hydroxide, calcium hydroxide, magnesium hydroxide sodium oxide, potassium oxide, lithium oxide, rubidium oxide, Calcium oxide, magnesium oxide or oxides thereof.

In the method for separating carbon dioxide, hydrogen ions are generated in one of the first and second compartments, and in the other of the first and second compartments. A voltage may be applied to the first and second electrodes to generate hydroxide ions. The applied voltage is the kind and concentration of the electrolyte contained in the first and second compartments, the type of oxidation reaction occurring in one compartment of the first and second compartments, and the reduction occurring in the other compartment of the black and the first and second compartments. It can be adjusted according to the type of reaction.

Specifically, the first and second electrodes are 0.42 V or more, 0.83 V or more, 1.03 V or more, and 2.06 V or more, and 10 V or less, 7 V or less, 5 V or less, 4 V or less, 3 V or less. A voltage of 2 V or less can be applied. Within this range, carbon dioxide in the mixed gas can be efficiently separated with little energy.

According to the separation method of carbon dioxide of the embodiment, the mixed gas may be directly supplied to any one of the first and second compartments to collect carbon dioxide in the mixed gas in any one of the compartments. As described below, in the first step, the mixed gas is directly supplied to the second compartment to collect carbon dioxide in the mixed gas, and in the second step, the mixed gas is directly supplied to the first compartment to capture the carbon dioxide in the mixed gas, and again. When the first step is repeated, the mixed gas may be directly supplied to the second compartment to collect carbon dioxide in the mixed gas. Accordingly, the method of separating carbon dioxide has the advantage that it is not necessary to provide a separate collecting device such as a scrubber to collect the carbon dioxide in the mixed gas.

The mixed gas is applied to the first and second electrodes before the voltage is applied to the first and second electrodes, and black is the first and second compartments after the voltage is applied to the first and second electrodes. It can be supplied to either compartment.

For example, the mixed gas may be supplied after a layer of hydroxide ions is generated in one of the first and second compartments by applying a voltage to the first and second electrodes. Specifically, as the mixed gas is applied with voltage to the first and second electrodes to generate hydroxide ions, the pH of any one of the first and second sections is about 10 to 14, about 11 to 14, about 12 to 14, about 13 to 14, about 10 to 13, about 11 to 13, about 12 to 13, about 10 to 12, about 11 to 12 black is about 10 to 11, Can be supplied. By supplying the mixed gas to any one compartment having such a pH, it is possible to improve the collection efficiency of carbon dioxide in the mixed gas. The mixed gas may be continuously supplied to one of the first and second compartments, or black may be periodically supplied. For example, the mixed gas may be periodically supplied when the pH of one of the first and second compartments reaches the above-mentioned range.

The carbon dioxide separation method is capable of separating pure carbon dioxide from various mixed gases containing carbon dioxide. Examples of such a mixed gas include a mixed gas requiring separation of carbon dioxide, industrial waste gas discharged from a natural gas power generation facility, a cement refining plant, and exhaust gas discharged from a combustion process of fuel.

The ratio of carbon dioxide in the mixed gas is not particularly limited.

At least 2 volume%, at least 5 volume%, at least 10 volume%, at least 15 volume%, at least 20 volume%, at least 30 volume%, at least 40 volume% black may be at least 50 volume%. In this range, more pure and concentrated carbon dioxide can be obtained. On the other hand, the upper limit of the ratio of carbon dioxide contained in the mixed gas is not particularly limited, 100% by volume or less, 90% by volume or less, 80% by volume or less, 70% by volume or less may be 60% by volume or less.

In the first step, the second compartment is a region where hydroxide ions are generated when a voltage is applied to the first and second electrodes. Therefore, in the first step, carbon dioxide in the mixed gas supplied to the second compartment can be selectively collected into the hydroxide ions present in the second compartment according to Equation 4 below.

[Equation 4]

C0 ₂ + OH ^" → HC0 ₃ —

In the method for separating carbon dioxide according to the embodiment, carbon dioxide in the mixed gas may be collected under normal pressure. Atmospheric pressure means natural pressure that is not pressurized or depressurized. Specifically, the carbon dioxide in the mixed gas may be collected in a pressure range of about 0.1 to 100 MPa. In addition, in the method for producing carbon dioxide according to the embodiment, the carbon dioxide in the mixed gas may be collected at a temperature of about 15 to 80 ^° C. or about 15 to 60 ^° C. Can be. Accordingly, carbon dioxide can be collected from the mixed gas by supplying the mixed gas such as industrial waste gas or exhaust gas directly to the first or second compartment without cooling the mixed gas.

The pH of any one of the first and second compartments in which the carbon dioxide in the mixed gas is collected is about 4 or more, about 5 or more, about 6 or more, about 7 or more, about 8 or more, about 9 or more, about 10 or more, or about 11 or more blacks may be about 12 or more, about 14 or less, about 13 or less blacks may be about 12 or less. Among these, for the selective capture of carbon dioxide, the pH of any one of the first and second compartments in which the carbon dioxide in the mixed gas is collected is about 10 to 14, about 11 to 14, about 12 to 14, about 13 to 14, About 10 to 13, about 11 to 13, about 12 to 13, about 10 to 12, about 11 to 12 black may be adjusted to about 10 to 11.

On the other hand, carbon dioxide in the mixed gas is selectively collected by hydroxide ions to generate hydrogen carbonate ions (HC0 ₃ —), and these hydrogen carbonates (HC _) change to dicarbonate (C0 ₃ ² —) at higher pH. Therefore, the carbon dioxide in the mixed gas supplied to any one of the first and second compartments may be collected by hydroxide ions to generate hydrogen carbonate ions and / or carbonate ions. In the present specification, the term 'carbonate-based ion' is used to collectively refer to a mixture of hydrogen carbonate ions, carbonate ions, black hydrogen carbonate ions and carbonate ions.

In addition, if carbon dioxide is collected continuously in either of the first and second compartments, the concentration of carbonic acid ions in the one compartment is increased, and some of the carbonic acid ions are combined with the dissociated cations in the electrolyte to form a salt. Can be precipitated. Therefore, when a mixed gas is supplied to one of the first and second compartments in which a voltage is applied to the first and second electrodes and hydroxide ions are generated, carbon dioxide in the mixed gas is collected to form a carbonic acid ion or a carbonic acid ion. Salts thereof, or salts of carbonate ions can be produced.

In order to improve the collection efficiency of the carbon dioxide, any one section in which hydroxide ions are generated in the first and second compartments may include a carbonate hydroxide black thereof in the above-described electrolyte. That is, in the first step, the second compartment may contain carbonate, hydroxide black as a electrolyte, and a mixture thereof. In the second step, the first compartment may be carbonate, hydroxide black as its electrolyte. May include a mixture. Therefore, in the first step, carbonate and hydroxide black may be supplied to the second compartment, and in the second step, carbonate and hydroxide black may be supplied to the first compartment.

Specific examples of the carbonate, hydroxide black and these mixtures include sodium carbonate, potassium carbonate, lithium carbonate, rubidium carbonate, calcium carbonate, magnesium carbonate, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, calcium hydroxide, and magnesium hydroxide black. These can be mentioned a combination.

Carbonate supplied as an electrolyte to any of the compartments in which hydroxide ions are generated in the first and second compartments is dissociated into cations and carbonates (C0 ₃ ² —), and the carbonate ions are carbon dioxide in the mixed gas as shown in Equation 5 below. It can be collected to produce hydrogen bicarbonate.

[Equation 5]

C0 ₂ + C0 ₃ ^{2 "} + ¾0 → 2HC0 ₃ —

In addition, the hydroxide supplied as an electrolyte to any of the compartments in which the hydroxide ions are generated in the first and second compartments is also dissociated into cations and hydroxide ions, and the hydroxide ions trap carbon dioxide in the mixed gas as described in Equation 4 to form carbon dioxide. Hydrogen ions can be produced.

In this way, the carbon dioxide in the initial mixed gas can be stably collected due to the carbonate and hydroxide black supplied as an electrolyte to one of the compartments in which the first and second compartments are added. In addition, carbon dioxide in the mixed gas may be continuously collected by hydroxide ions generated by applying voltage to the first and second electrodes.

Carbonate ions dissociated from the carbonate supplied to the electrolyte and hydroxide ions dissociated from the hydroxide supplied to the electrolyte or generated by applying a voltage to the first and second electrodes which are black have the advantage of selectively trapping carbon dioxide in the mixed gas, Thereafter, in the second step of reconverting to carbon dioxide, there is an advantage that carbon dioxide can be regenerated without a separate energy supply.

The concentrations of carbonates, hydroxides, blacks and the like supplied to the electrolyte may be appropriately adjusted in consideration of carbon dioxide capture efficiency and economic efficiency. Can be. Specifically, the electrolyte may be supplied at a concentration below the saturation concentration of the electrolyte, and more specifically, the electrolyte may be supplied at 50%, 1% to 30% black, and 22% to 28% of the saturation concentration. As an example, the saturation concentration of sodium carbonate at 15 ^° C is 1.55 M. Thus, when sodium carbonate is used as the electrolyte, the concentration of sodium carbonate is 0.0155 to 0.775 M, 0.0155 to 0.465 M, or 0.341 to 0.434 M at 15 ^° C. in either compartment where the first and second compartment thick hydroxide ions are generated. Sodium carbonate can be fed. Within this range, carbon dioxide can be captured economically and efficiently.

When carbon dioxide is collected in the first step to produce carbonic silver or a salt thereof, a voltage may be applied such that the first electrode becomes a cathode and the second electrode becomes an anode.

The time when the carbon dioxide is collected and the carbonate-based salts or salts thereof are generated in detail is the pH of the first or second compartment, the concentration of the carbonate-based ions in the electrolyte solution of the first or second compartment, or the black or the first or second compartment. This can be checked through electrical conductivity.

For example, when voltage is applied to the first and second electrodes in the first step, hydroxide ions are generated in the first and second compartments, so that the second compartment has a high pH, or black in the first stage. Carbonate, hydroxide black can be fed to these mixtures as an electrolyte so that the second compartment can exhibit high pH. However, since the hydroxide ions and the carbonate ions are used to capture carbon dioxide as in Equation 4 and Equation 5, as the carbon dioxide is collected, the pH of the second compartment of the first stage becomes lower gradually. As a result of the experiments of the inventors, as the carbon dioxide is collected in the crab step, the pH of the 1 2 compartment is gradually lowered to maintain a constant value between about 7 to 9, about 7 to 8.5 black and about 7.5 to 8.5 It confirmed that it became. It can be seen that the reaction of the second compartment has reached equilibrium from the fact that the pH of the second compartment of the first stage is maintained at a constant value. Therefore, when the pH of the second section of the first step maintains a constant value between about 7 and 9, a voltage can be applied such that the first electrode becomes the cathode and the second electrode becomes the anode. In another example, while carbon dioxide is collected in the second compartment of the first stage, hydrogen is continuously generated in the nearly one compartment so that the pH of the crab is gradually lowered. Therefore, when the pH of the first section of the first step is 0 to 3, 1 to 3, 2 to 3, 0 to 2, 1 to 2 black is 0 to 1, the first electrode becomes the cathode and the second electrode A voltage can be applied to this anode.

As another example, when the concentration of carbonic acid ions in the second compartment is measured directly or indirectly, if enough carbonic acid ions are generated, for example, when the concentration of the carbonic acid is higher than or equal to the saturation concentration, the first electrode becomes a cathode and the second electrode. Voltage can be applied to this anode.

As another example, as the carbon dioxide is collected in the second compartment of the first step, the concentration of the carbonic acid ions increases to increase the electrical conductivity of the second compartment. Therefore, by measuring the electrical conductivity of the second section of the first step, the increase in electrical conductivity is 0 raS / cm to 50 mS / cm, 10 mS / cm to 50 mS / cra, 20 raS / cm to 50 mS / cm, When 30 mS / cm to 50 mS / cm, black is 40 mS / cm to 50 mS / cm, a voltage may be applied such that the first electrode becomes a cathode and the second electrode becomes an anode.

The method of applying a voltage to the first and second electrodes is not particularly limited so that the first electrode serving as the anode becomes the cathode in the first step, and the second electrode serving as the cathode serves as the anode. In the power supply connected to the electrode, it may be performed by applying a voltage to the first and second electrodes by setting which of the first and second electrodes will function as the anode black or the cathode. Typically, it is very easy to set which of the two electrodes to function as the anode in the power supply. Therefore, the first and second steps may be performed by setting the anode and the cathode to be interchanged when a signal indicating that the carbonate-based ions or salts thereof are generated through the sensors installed in the first and second compartments. The signal that the carbonate ions or salts thereof are sufficiently produced means that the pH of the first or second compartment, the concentration of the carbonate ions, and the black or black electrical conductivity have reached a certain value.

In the first step, a voltage is applied to the first and second electrodes such that the first electrode serving as the anode becomes the cathode and the second electrode serving as the cathode becomes the anode. Upon application, the carbonate-based ions or salts thereof produced in the second compartment are reconverted to carbon dioxide.

Specifically, when voltage is applied to the first and second electrodes such that the first electrode becomes the cathode and the second electrode becomes the anode, the first compartment becomes a region where hydroxide ions are generated and the second compartment generates hydrogen ions. It becomes an area. Therefore, the carbonate-based ions or salts thereof present in the second compartment may be converted into carbon dioxide according to the pH equilibrium principle as shown in Equations 6 and 7. Specifically, carbonate ions dissolved in the electrolyte black carbonate dissociated from the carbonate is converted to hydrogen carbonate ions as shown in Equation 6, hydrogen carbonate ions may be converted to carbon dioxide as shown in Equation 7.

[Equation 6]

C0 ₃ ^{2 "} + H ⁺ → HC0 ₃ ^"

[Equation 7]

HC0 ₃ ^" + H ⁺ → C0 ₂ + 0

In the second step, the carbonate-based ions or salts thereof may be reconverted to carbon dioxide at a temperature of about 15 to 80 ^° C. black or about 15 to 60 ^° C. Accordingly, even if the industrial waste gas black or the mixed gas such as the exhaust gas is used without cooling, carbon dioxide can be separated from the mixed gas with excellent efficiency.

In the second step, the pH of the second compartment in which the carbonate-based salt or salt thereof is reconverted to carbon dioxide may be about 7 or less, about 6 or less, about 5 or less, about 4. or less and about 3 or less, and black may be about 2 or less, About 0 or more, about 1 or more Black is about 2 It may be abnormal. Among them, for the efficient reconversion to carbon dioxide,

The pH of the second stage of the second stage is about 0-6, about 0-5 Pa about 0-4, about 0-3, about 0-2, about 0-1, about 1-6, about 1-5, about 1 to 4, about 1 to 3, about 2 to 6, about 2 to 5, about 2 to 4 or about 2 to 3.

On the other hand, a lower voltage is required when generating hydrogen ions through oxidation reaction of hydrogen gas than when generating hydrogen ions through oxidation reaction of water. In the second section of the first stage, hydrogen gas is generated according to Equation 3. In the second section of the second stage, the hydrogen gas is oxidized to generate hydrogen ions, thereby saving energy.

Specifically, when the carbonic acid-based ions or salts thereof are converted into carbon dioxide by hydrogen ions generated through oxidation reaction of hydrogen gas in the second step, 0.83 V to 2 V at the first and second electrodes. The voltage of can be applied. Applying a voltage in this range can significantly reduce the energy required to separate carbon dioxide. In addition, the theoretical voltage for oxidizing water to generate hydrogen ions and oxygen gas is 2.06V. Therefore, by adjusting the voltage range as described above, the purity of carbon dioxide is improved by consuming hydrogen gas generated in the second section of the first stage and suppressing generation of oxygen gas in the second section of the second stage. You can.

On the other hand, as the ratio of carbon dioxide in the mixed gas increases, the capture efficiency of carbon dioxide is improved, and the purity and yield of carbon dioxide obtained by reconversion of carbonate-based ions or salts thereof may be improved. Accordingly, the method of separating carbon dioxide according to the embodiment may pretreat the mixed gas before the first step.

For example, before the mixed gas is supplied to the first or second compartment, the mixed gas may be contacted with a solvent to remove other gases other than carbon dioxide from the mixed gas.

In the case of using the above-described industrial waste gas as the mixed gas, the mixed gas is a gas such as S0 _X , HF, HC1, NH ₃₎ Cl _{2 j} SiF ₄ , 0 ₂ , N ₂ , CO, N0 _X , SH _{2 in} addition to carbon dioxide. It may include. C0 ₂ may be a pH of 3.5 to 5.5 which is not very soluble in _{water, S0 X, HF, HC1,} NH 3, Cl 2, SiF 4 and so on is smoothly dissolved. Therefore, the mixed gas has a pH of about 3. 5 to Ί, about 3.5 to 6 ᅳ about 3. 5 to 5. 5, about 3. 5 to 5 or about 3.5 to 4 in contact with water so that the solubility of the mixed gas in water in the above pH range is higher than C0 ₂ The gas, for example, S0 _X , HF, HC1, NH ₃₎ Cl ₂ , SiF ₄ can be removed in advance.

Specifically, the mixed gas is passed through a container, a black tube, or the like, containing the water in the pH range, or black, by injecting water in the pH range in a flow through which the mixed gas passes, to advance other gases other than C0 _{2 in} the mixed gas in advance. Can be removed

For example, the pretreatment of the mixed gas may be performed using a scrubber. Specifically, the pretreated mixed gas may be obtained by filling the scrubber with water in the pH range and dispersing the mixed gas under high pressure through a porous spray plate into a scrubber. In addition, after supplying the mixed gas to the scrubber inlet, water of the pH range may be injected into the flow of the mixed gas to obtain the mixed gas pretreated from the outlet of the scrubber.

In addition, other gases other than C0 ₂ not removed in this pretreatment step may be naturally dissolved because they do not dissolve in the high pH electrolyte in any one compartment where hydroxide ions are generated in the first and _second compartments. Specifically, the gas such as 0 ₂ , N ₂ , CO, N0 _X , SH _{2 in} the mixed gas does not dissolve in the high pH electrolyte solution, so even if the mixed gas containing such gas is supplied to the first or second compartment, the mixed gas You can selectively capture C¾ from.

On the other hand, the inventors have found that, after a lot of research, S¾ improves the capture efficiency and reconversion efficiency of CO ₂ when the mixed gas contains CO ₂ and SO ₂ . Therefore, if the mixed gas contains C0 ₂ and S0 ₂ , carbon dioxide can be separated from the mixed gas more efficiently even if the pretreatment step is omitted. In addition, sulfate ions (SO ₄ ² —) can be obtained from SO ₂ with the separation of carbon dioxide.

Specifically, when the mixed gas is supplied to the second section of the first step as described above, the carbon dioxide in the mixed gas is converted by the hydroxide ions as shown in Equation 4 above. Is collected. In addition, sulfur dioxide in the mixed gas may be collected by hydroxide ions as shown in Equation 8.

[Equation 8]

S0 ₂ + OH— → S0 ₃ ^{2 "} + H +

At this time, the mixed gas may not be pretreated so that the mixed gas may contain NO _x . However, as described above Ν0 _Χ is not dissolved in an electrolytic solution of high ρΗ. Therefore, ΝΟχ can be removed by not melting in the electrolyte when supplying the mixed gas to the second compartment of the first stage.

If sulfur dioxide is continuously collected by the hydroxide ions as shown in Equation 8, the concentration of sulfite ions (sul fi te, S0 ₃ ² —) in the second compartment of the first step is increased, similarly to the carbonic acid-based silver. In addition, some sulfite ions may be combined with cations derived from an electrolyte or the like to precipitate as a salt. Therefore, when the mixed gas is supplied to the second section of the first stage, carbon dioxide in the mixed gas is collected to form carbonate-based ions, black carbonate-based ions and salts thereof, and salts of black carbonate-based ions, and sulfur dioxide in the mixed gas. This trapping can produce sulfite ions, sulfite ions and salts thereof, and salts of black or sulfite ions.

As described above, the first electrode serving as the anode in the first step becomes the cathode, and the voltage is applied to the first and second electrodes so that the second electrode serving as the cathode becomes the anode. The ions or their salts can be reconverted to carbon dioxide and sulfate ions or salts thereof can be produced from the sulfite ions or salts thereof. The first and second steps may be performed as described above, unless otherwise described.

The sulfite ions dissociated from the sulfite ions or salts thereof present in the second compartment of the second step may react with water to generate hydrogen ions as shown in Equation 9 below.

[Equation 9]

S0 ₃ ² — + ¾0 → S0 ₄ ^{2 "} + 2H + + 2e

In the second section of the second step, the carbonic acid-based ions or salts thereof are reconverted into hydrogen dioxide by hydrogen ions, and thus the reaction for generating sulfate ions from sulfite ions generating hydrogen ions results in reconversion of carbon dioxide. Can be promoted. In addition, sulfate ions generated from sulfite ions can improve the electrical conductivity by increasing the total amount of ions in the second compartment.

On the other hand, since the pair of crab first and second compartments are separated by a cation exchange membrane, the hydrogen ions generated in the second compartment of the second stage can move through the cation exchange membrane to the first compartment by electrical attraction. However, even in such a case, since sulfite ions or salts thereof further generate hydrogen ions as in Equation 9, the carbon dioxide reconversion efficiency may not be reduced.

Meanwhile, in the second section of the second step, hydrogen ions and oxygen gas are generated due to the oxidation reaction of water as in Equation 1 above. Accordingly, not only carbon dioxide but also oxygen gas may be released from the second compartment of the second stage, thereby reducing the purity of the carbon dioxide obtained in the second compartment of the second stage. However, sulfite ions dissociated from the sulfite ions or salts thereof present in the second compartment in the second step may consume oxygen gas generated in the second compartment by reacting with oxygen to generate sulfate ions as shown in Equation 10 below. . Accordingly, it is possible to improve the purity of the carbon dioxide emitted from the second compartment of the second step.

[Equation 10]

2S0 ₃ ^{2 "} + 0 ₂ → 2S0 ₄ ^2"

On the other hand, hydrogen ions are required to reconvert carbon dioxide from carbonate ions or salts thereof in the second compartment of the second step, and the hydrogen ions are not sulfur dioxide or silver sulfite according to Equation 9, but the electrolysis of water according to Equation 1 above. When supplied through the oxidation reaction of the salt, it is possible to prevent the generation of oxygen gas in the second section of the second step to provide a high purity carbon dioxide.

Specifically, a voltage of 1.03 V to 2 V may be applied to the first and second electrodes in order to minimize the oxygen gas generated in the second section of the second step. Since the theoretical voltage for oxidizing water to generate hydrogen ions and oxygen gas is 2.06 V, oxygen gas generation can be suppressed by adjusting the voltage range as described above. On the other hand, in the carbon dioxide separation method according to the embodiment may repeat the first step after the second step. Thereby, high purity and high concentration of carbon dioxide can be separated continuously from the mixed gas.

Referring to FIG. 10, hydroxide ions are generated in the first compartment 1st CP of the second stage similarly to the second compartment 2nd CP of the first stage (see 10 and 20 of FIG. 10). Accordingly, the second step may collect carbon dioxide in the mixed gas including carbon dioxide in the first compartment to generate carbonic acid ions or salts thereof (see 20 in FIG. 10). Since the method of capturing carbon dioxide in the second compartment of the first stage has been described in detail above, a detailed description of the method of capturing carbon dioxide in the first compartment of the second stage will be omitted. As an example, in the first step, carbonate and hydroxide as an electrolyte are supplied to the second compartment to improve the collection efficiency of carbon dioxide, and in the second step, carbonate and hydroxide are used as the electrolyte in the first compartment. Black can feed these mixtures. In addition, as in the second compartment of the first stage, the sulfur dioxide is captured together with the carbon dioxide, the first compartment of the second stage can also collect sulfur dioxide together with the carbon dioxide. As described above, if carbon dioxide in the mixed gas is collected in the first compartment (1st CP) of the second stage to generate carbonic acid-based ions or salts thereof, hydrogen ions are generated in the first compartment when the first stage is repeated. The carbonate-based ions or salts thereof may be reconverted to carbon dioxide (see 10 ′ in FIG. 10). This allows the use of both pairs of first and second compartments to separate more carbon dioxide from more mixed gases.

9, the electrolysis device includes a first electrode (1st EL); Second electrode (2nd EL); A cat ion exchange membrane (CEM) positioned between the first electrode and the second electrode, and a pair of first and second compartments separated by the cation exchange membrane, the second electrode positioned on the first electrode side; F irst compartment (1st CP) and second electrode A second compartment located on the side (2nd CP).

As described above, the carbon dioxide in the mixed gas in the second compartment of the first stage is captured by the hydroxide ions, and in the second compartment of the second stage, the carbonic acid-based ions or salts thereof may be converted into carbon dioxide by hydrogen ions. . If a pair of first and second compartments are separated by an anion exchange membrane, hydroxide ions can pass through the anion exchange membrane by electrical attraction to other compartments, thereby degrading the capture efficiency of carbon dioxide. On the other hand, when the pair of first and second compartments are separated by the cation exchange membrane, hydrogen ions may pass through the cation exchange membrane by electrical attraction to other compartments, thereby reducing carbon dioxide reconversion efficiency. In the case of the anion exchange membrane, only the ion species passing through the anion exchange membrane is hydroxide ions, but in the case of the cation exchange membrane, in addition to the hydrogen ions, the amount of dissociated from the electrolyte is different. Considering this point, it can be seen that the degree of reduction of the carbon dioxide collection efficiency due to the migration of hydroxide ions by the anion exchange membrane is greater than the degree of reduction of the reconstruction efficiency of the carbon dioxide by the transfer of hydrogen ions by the different exchange membrane. In addition, referring to 20 of FIG. 9, hydrogen ions are provided in more routes than hydroxide ions. For example, hydrogen ions can be obtained from hydrogen gas generated at the time of capture of carbon dioxide. When sulfur dioxide is collected together with carbon dioxide, hydrogen ions are further generated while sulfate ions are generated from sulfite ions. Therefore, in the method for separating carbon dioxide according to the embodiment, by employing a cation exchange membrane, both the capture efficiency and the reconversion efficiency of carbon dioxide were maintained at excellent levels.

The method for separating carbon dioxide according to the embodiment may further include regenerating the electrolyte after the second step. Then, after the electrolyte regeneration, the first step may be repeated.

Regenerating the electrolyte may be performed by mixing the electrolyte solution of the first and second compartments, and supplying the electrolyte solution mixed uniformly to the first and second compartments.

More specifically, regenerating the electrolyte may be performed by applying a voltage to the first and second electrodes to adjust the pH of one compartment to 3-5. After adjusting the pH of the compartments to 11 to 12, the electrolyte of the first and second compartments may be mixed to produce an electrolyte of pH 8 to 10. The resulting electrolyte of pH 8 to 10 may be supplied to the first and second compartments again. The electrolysis device may comprise two or more pairs of first and second compartments using a bipolar membrane. When voltage is applied to the first and second electrodes, water is separated into hydrogen ions and hydroxide ions by the bipolar membrane, and the hydrogen ions and hydroxide ions can move by electrical attraction. In the electrolysis device, the bipolar membrane may be replaced with a water migration passage whose sidewall is composed of the bipolar membrane. When water is poured into the water passage and voltage is applied to the first and second electrodes, water is separated into hydrogen ions and hydroxide ions in the bipolar membrane where the water is a sidewall. Hydrogen ions are supplied by an electrical attraction to the compartment located on the anode side of the pair of first and second compartments based on the cation exchange membrane located between the first and second compartments, and the compartment located on the cathode side is electrically Hydroxide ions can be supplied by attraction.

Referring to FIG. 11, the electrolysis device includes a first electrode 1st EL; Second electrode 2nd EL; A bipol ar membrane (BM) positioned between the first and second electrodes; between the first electrode (1st EL) and the bipolar membrane (BM) and between the bipolar membrane (BM) and the second electrode (2nd EL) Two cation exchange membranes (CEM) located between the; Two pairs of first and second partitions separated by the respective cation exchange membranes (CEMs), two first compartments (1st CP) and a second electrode (2nd EL) positioned on the first electrode (1st EL) side. It may include two second compartment (2nd CP) located on the side). Referring to FIG. 12, the electrolysis device includes a first electrode 1st EL; A second electrode (2nd EL); two or more bipol ar membranes (BMs) positioned between the first and second electrodes; Three or more cation exchange membranes (CEM) positioned between the first electrode 1st EL and the bipolar membrane BM, between the bipolar membrane and the bipolar membrane, and between the bipolar membrane BM and the second electrode 2nd EL; At least three pairs of first and second compartments separated by the respective cation exchange membranes (CEM), wherein at least three first compartments (1st CP) and a second electrode (2nd) positioned on the first electrode (1st EL) side. It may include three or more second compartments (2nd CP) located on the EL side. In the case of using such an electrolysis device, a mixed gas may be supplied to each of two or more second sections in the first step. In addition, a mixed gas may be supplied to each of two or more first sections in the second step. In addition, the carbonate-based ions or salts thereof generated in the compartment may be reconverted to carbon dioxide in the compartment while changing the roles of the first and second electrodes as the anode and the cathode.

The electrolysis device may be configured as known in the art. Hereinafter, the component which comprises the said electrolysis apparatus is demonstrated in detail.

As the cation exchange membrane, various kinds of divalent silver exchange membranes applied to an electrolysis device or a fuel cell may be used. Specifically, as the cation exchange membrane, for example, commercially available Nafion from Dupont, CMX from Tokuyama, Japan, and the like can be used.

The first and second electrodes may be installed at appropriate positions so as to exert an electrical attraction to the ionic species included in the first and second compartments. The shape of the first and second electrodes is not particularly limited, and may be variously modified as known in the art.

As the first and second electrodes, all kinds of electrodes applied to an electrolysis device or a fuel cell may be used. For example, various types of conductors may be used as the first and second electrodes, or an electrode including a black electrode substrate and a catalyst applied to the electrode substrate may be used. The above conductors include titanium (Ti), stainless steel, nickel (Ni), nickel / chromium (Ni / Cr) alloys, platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), and rhodium ( Rh), ruthenium (Ru) or those selected from the group consisting of these oxides can be used. In addition, in an electrode including a catalyst coated on the electrode substrate, carbon cloth or the like may be used as the electrode substrate, and platinum (Pt), ruthenium (Ru), osmium (0s), or baffle may be used as the catalyst. Radium (Pd), iridium (Ir), carbon (0, other transition metals and mixtures thereof) may be used.

The first and second electrodes may be connected to a power supply device. remind As the power supply device, voltages in the above-described ranges may be applied to the first and second electrodes, and if it is possible to change the roles of the first and second electrodes as the anode and the cathode, those known in the art. Both can be used.

The electrolysis device may be connected to one or more reservoirs so as to continuously supply a mixed gas and an electrolyte to the electrolysis device, and collect carbon dioxide and the like obtained from the electrolysis device.

In addition, the electrolysis device includes a fluid flow rate adjusting device capable of adjusting the flow rate of the fluid flow; Sensors for monitoring the status of the first and second compartments; And a recording device capable of recording an electrical signal related to the electrolysis device and a change in solution properties of each compartment.

In addition to the above-described configuration, the electrolysis device may further include a configuration commonly employed in the electrolysis device known in the art to which the present invention pertains, or may be employed as a part of a large-scale facility in connection with other device parts.

On the other hand, according to another embodiment of the present invention, the carbon dioxide separation system in a mixed gas containing carbon dioxide, the first electrode; Second electrode; A cation exchange membrane positioned between the first and second electrodes; A pair of first and second compartments separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side; And a power supply for applying a voltage such that the first electrode becomes an anode and the second electrode becomes a cathode, and then applies a voltage such that the first electrode becomes a cathode and the second electrode becomes an anode. A system is provided. The carbon dioxide separation system is a system capable of performing the above-described method of separating carbon dioxide, which has been described in detail above, and thus a detailed description thereof will be omitted.

Since the method for separating carbon dioxide according to one embodiment of the present invention is capable of purely separating carbon dioxide from a mixed gas discharged during combustion, it is expected to be applicable to various technical fields for separating, using, or treating carbon dioxide. In particular, the carbon dioxide separation method is ecus technology It is expected to be able to provide carbon dioxide useful for cost reduction and useful in fields requiring ultra high purity carbon dioxide, for example, chemical reaction processes. Hereinafter, the operation and effects of the invention will be described in more detail with reference to specific examples. However, this is presented as an example of the invention, whereby the scope of the invention is not limited in any sense. Example 1 Separation of Carbon Dioxide

Carbon dioxide was separated from the mixed gas using an electrolysis device as shown in FIG. 2. Specifically, the supply of 15 ° C based on an aqueous solution of sodium carbonate of about 0.4 M in the electrolyte in the anode compartment, and supplying the 15 ^° C based on aluminum oxide aqueous solution of about 1.0 M in the electrolyte in the cathode compartment and the intermediate compartment to the electrolytic solution 15 ^° C A standard about 1.0 M aqueous sodium chloride solution was supplied. A voltage of 4 V was applied to the positive electrode and the negative electrode, and a mixed gas containing 10 vol% of carbon dioxide was supplied to the negative electrode compartment at a rate of 80 cc / min.

Referring to FIG. 13, the initial pH of the cathode compartment at room temperature (25 ^° C.) was measured to be about 11.75. As the carbon dioxide is continuously collected, the pH is gradually lowered, and it is confirmed that the pH is maintained at about 7.9.

On the other hand, referring to Figure 14, the initial pH of the anode compartment at room temperature (25 ^° C) is about

It is confirmed that the pH is continuously lowered with time since hydrogen ions are generated by electrolysis of water in the anode compartment.

When the pH reaches a constant value in the cathode compartment, it can be expected that the reaction in the cathode compartment has reached equilibrium. Therefore, when the pH of the negative electrode compartment reached a constant value, the carbonate-based black of the negative electrode compartment moved the electrolyte solution containing its salt to the positive electrode compartment.

Anode compartment exhibits a very low p _H as described above and the carbon black-based ion moved to the cathode compartment has been released is again a salt thereof is converted to carbon dioxide.

In the cathode compartment before moving the electrolyte from the cathode compartment to the anode compartment As a result of measuring the concentration of carbonic acid ions, the concentration at room temperature (25 ^° C) was about 1.0 M, and the concentration at room temperature was about 1.0 M when the concentration of hydrogen ions in the anode compartment was measured.

In this way, the carbon dioxide generated and the at room temperature for preparing a NaHC0 ₃ solution and S0 ₄ solution, H ₂ of about 0.5 M to approximately 1.0 M was added to H ₂ S0 ₄ solution of about 0.5 M in the NaHC0 ₃ solution was about 1.0 M The content was measured to define the amount of carbon dioxide expected to be theoretically recovered in the anode compartment. Since 1 mol of H ₂ S0 ₄ dissociated to generate 2 mol of hydrogen ions, the concentration of the H ₂ S0 ₄ solution was adjusted to 0.5 M.

Carbon dioxide generation amount according to the addition of the H ₂ S0 ₄ solution of about 0.5 M is

It was expressed as 15 ·, and the pH change amount is represented by the surface graph. The amount of carbon dioxide generated in the anode compartment according to Example 1 is represented by A of FIG. 15.

Referring to Figure 15, it is confirmed that all of the pure carbon dioxide (pure CO ₂ ) expected to be recovered theoretically in the anode compartment. The purity of carbon dioxide released from the anode compartment was about 100% by volume. Example 2 Separation of Carbon Dioxide

In the same manner as in Example 1, the electrolyte was supplied to the cathode compartment, the anode compartment, and the intermediate compartment, and carbon dioxide was separated from the mixed gas in the same manner as in Example 1 except that the temperature of the electrolysis device was increased to 50 ^° C.

Referring to FIG. 13, the initial pH of the cathode compartment at 50 ^° C. was measured at about 11. And, as the carbon dioxide continues to be collected, the pH is gradually lowered, and it is confirmed that the pH is maintained at about 8.2.

On the other hand, referring to Figure 14, the initial pH of the anode compartment at 50 ^° C is about

1.4, although the pH initially increases slightly, the overall pH decreases over time.

As described above, the first and second steps were carried out at 50 ^° C., and the purity of the carbon dioxide released from the anode compartment was about 100% by volume. In the method for separating carbon dioxide according to an embodiment of the present invention, the exhaust gas is normally discharged. As a result of conducting at a temperature (about 50 ^° C), no physical defects of the electrolysis device were found, and there was no difference in tendency and separation efficiency from Example 1 implemented at room temperature. As a result, it was confirmed that the present invention can be directly applied to the carbon dioxide separation system of the present invention without cooling the exhaust gas. Example 3 Separation of Carbon Dioxide

Carbon dioxide was separated from the mixed gas using an electrolysis device as shown in FIG. 10. Specifically, an aqueous solution of about 0.4 M sodium carbonate based on 15 ° C. was supplied to Crab 1 and the second compartment. A voltage of 4 V is applied to the first and second electrodes so that the first electrode becomes the anode and the second electrode becomes the cathode, and the mixed gas containing 10 vol% of carbon dioxide is added to the second compartment at 80 cc / min. Feed at rate (see 10 of FIG. 10).

The initial pH of the second compartment at room temperature was measured to be about 11.75. And, as the carbon dioxide continues to be collected, the pH was gradually lowered and reached about 7.9 to be maintained.

When the pH reaches a constant value in the second compartment, it can be expected that the reaction in the second compartment has reached equilibrium. Therefore, when the pH of the second compartment reaches a constant value, a voltage of 2.5 V or 3 V is applied to the first and second electrodes so that the first electrode becomes the cathode and the crab electrode becomes the anode (20 in FIG. 10). Reference) . As the second electrode functions as an anode, hydrogen ions were generated in the second compartment. When a voltage of 2.5 V was applied to the first and second electrodes, the pH was lowered from 8 to 6.7, and a voltage of 3 V was applied. When it was confirmed that the pH is lowered from 8 to 1.8. As a result, the carbonate-based black silver salt produced in the second compartment was converted into carbon dioxide and released.

After the voltage was applied such that the first electrode became the cathode and the second electrode became the anode, the concentration change of the inorganic carbon in the second compartment with time was measured and shown in FIG. 16. Referring to FIG. 16, when a voltage of 3 V is applied to the first and second electrodes, it is confirmed that a larger amount of carbon dioxide is released faster than when a voltage of 2.5 V is applied. However, it is about 3 hours whether the voltage of 3 V or the voltage of 2.5 V is applied to the first and second electrodes. As time passes, it is confirmed that all carbon dioxide trapped in the second compartment is released. When a voltage of 2.5 V and a voltage of 3 V were applied to the first and second electrodes, carbon dioxide having a purity of about 90% by volume was emitted from the second compartment.

Meanwhile, as the second electrode functions as an anode and the first electrode functions as a cathode, hydroxide ions were generated in the first compartment. Accordingly, when a mixed gas was supplied to the first compartment, carbon dioxide was collected. Thereafter, when the pH of the first compartment decreases gradually and reaches a constant value, a voltage of 4 V is applied to the first and second electrodes so that the first electrode becomes the anode and the second electrode becomes the cathode. The carbon dioxide-based ions or salts thereof were converted into carbon dioxide while carbon dioxide was collected in the second compartment (see 10 'in FIG. 10). By repeating this process, it was confirmed that carbon dioxide can be continuously separated from the mixed gas.

[Explanation of code]

Θ: cathode

AC: anode compartment

CC: cathode compartment

MC: middle compartment

1st EL first electrode

2nd EL second electrode

1st CP first compartment

2nd CP second compartment

I EM: ion exchange membrane CEM: catorr exchange membrane AEM: an ion exchange membrane BM: bipolar membrane

Mix: Mixed Gas

10: State of the first stage

20: State of the second phase

10 '： State of the first stage after the second stage

100: first electrolysis device

200: second electrolysis device

300: third electrolysis device

MX: salt consisting of cation (M ⁺ ) and negative 0Γ)

Claims

【Claims】

【Claim 1】

anode; cathode; an ion exchange membrane located between the anode and the cathode; and a method of separating carbon dioxide using a device including a pair of anode compartments and a cathode compartment separated by the ion exchange membrane,

A first step of collecting carbon dioxide in a common gas containing carbon dioxide in the cathode compartment where hydroxide ions are generated when a voltage is applied to the anode and cathode to generate carbonate ions or salts thereof; and

Carbon dioxide comprising a second step of reconverting the carbonate ion or its salt into carbon dioxide by moving the carbonate ion or its salt from the cathode compartment to the anode compartment where hydrogen is generated when a voltage is applied to the anode and cathode. How to separate.

[Claim 2]

The method of separating carbon dioxide according to item 11, wherein a voltage of 0.42 V or more and 10 V or less is applied to the anode and cathode.

【Claim 3】

The method of separating carbon dioxide according to claim 1, wherein the mixed gas contains carbon dioxide in an amount of 2% by volume or more.

[Claim 4]

The method of separating carbon dioxide according to claim 1, wherein the cathode compartment contains carbonate, hydroxide, or a mixture thereof as an electrolyte.

【Claim 5】

The method of claim 1, wherein when the pH of the cathode compartment is maintained at a constant value between 7 and 9, carbonate ions or salts thereof from the cathode compartment are moved to the anode compartment.

[Claim 6]

The method of separating carbon dioxide according to claim 1, wherein when the pH of the anode compartment becomes 0 to 3, carbonate ions or salts thereof from the cathode compartment are moved to the anode compartment.

【Claim 7】 The method of separating carbon dioxide according to claim 1, wherein when the concentration of carbonate ions in the cathode compartment is higher than the saturation concentration, the carbonate ions or salts thereof in the cathode compartment are moved to the anode compartment.

[Claim 8]

The method of separating carbon dioxide according to claim 1, wherein when the increase in electrical conductivity in the cathode compartment is 10 mS/cm to 50 mS/cm, carbonate ions or salts thereof in the cathode compartment are moved to the anode compartment.

【Claim 9】

The method of separating carbon dioxide according to claim 1, wherein hydrogen gas generated in the cathode compartment is moved to the anode compartment.

[Claim 10]

The method of separating carbon dioxide according to paragraph 19, wherein a voltage of 0.83 V to 2 V is applied to the anode and cathode.

【Claim 11】

The method of separating carbon dioxide according to claim 1, wherein the mixed gas is brought into contact with water of pH 3.5 to 7 and then injected into the cathode compartment.

[Claim 12]

The method of claim 1, wherein in the first step, carbon dioxide in the mixed gas is collected to produce carbonate ions or salts thereof, and sulfur dioxide is collected to produce sulfurous acid ions or salts thereof.

【Claim 13】

The method of claim 12, wherein in the second step, the carbonate ion or salt thereof and the sulfurite ion or salt thereof are moved from the cathode compartment to the anode compartment to reconvert the carbonate ion or salt thereof to carbon dioxide in the anode compartment, and the sulfite ion Or a method of separating carbon dioxide that produces sulfate ions or a salt thereof from a salt thereof.

[Claim 14]

The method of separating carbon dioxide according to claim 13, wherein a voltage of 1.03 V to 2 V is applied to the anode and cathode.

【Claim 15】 The method of separating carbon dioxide according to claim 1 12, wherein the anode compartment further includes a catalyst.

【Claim 16】

The method of claim 15, wherein the catalyst includes a compound containing Co ²⁺ , Fe ²⁺ , Fe ³⁺ , Mn ²⁺ , Zn ³⁺ , Au ²⁺ or Cu ²⁺ and Au, Ag, Ru or Ir. A method of separating carbon dioxide using one or more compounds selected from the group consisting of compounds.

[Claim 17]

The method of separating carbon dioxide according to claim 16, wherein a voltage of 0.83 V to 20 V is applied to the anode and cathode.

【Claim 18】

The method of claim 1, wherein an anion exchange membrane separates the anode compartment and the intermediate compartment so that an intermediate compartment exists between the pair of anode compartments and the cathode compartment, and an anion exchange membrane separates the intermediate compartment and the cathode compartment. ，Separation method of carbon dioxide.

【Claim 19】

The method of separating carbon dioxide according to item 18, wherein seawater, sewage, wastewater, industrial water, or a mixture thereof is supplied to the middle compartment to desalinate the water.

[Claim 20]

The method of claim 1, wherein the device includes an anode; cathode; One bipolar film located between the anode and the cathode; Two ion exchange membranes located between the anode and the bipolar membrane and between the bipolar membrane and the cathode; A method of separating carbon dioxide using an apparatus comprising two pairs of anode compartments and cathode compartments separated by respective ion exchange membranes.

【Claim 21】

The method of claim 1, wherein the device includes an anode; cathode; two or more bipolar films positioned between the anode and the cathode; Three or more ion exchange membranes located between the anode and the bipolar membrane, between the bipolar membrane and the bipolar membrane, and between the bipolar membrane and the cathode; Separation of carbon dioxide using a device including three or more pairs of anode compartments and cathode compartments separated by each ion exchange membrane. method.

[Claim 22]

The method of separating carbon dioxide according to claim 1, wherein carbonate ions or salts thereof generated in the cathode compartment of the first electrolysis device are moved to the anode section of the second electrolysis device, which is different from the first electrolysis device.

【Claim 23】

A system for separating carbon dioxide from a common gas containing carbon dioxide, including an anode; cathode; A cathode compartment in which hydroxide ions are generated when a voltage is applied to the anode and the cathode, and carbon dioxide in a common gas containing carbon dioxide is collected to generate carbonate ions or salts thereof; When a voltage is applied to the anode and the cathode, hydrogen ions are generated, and an anode compartment that reconverts carbonate ions or salts thereof transferred from the cathode compartment into carbon dioxide; and a continuous exchange membrane separating the anode compartment and the cathode compartment.

【Claim 24】

first electrode; second electrode; a cation exchange membrane positioned between the first electrode and the second electrode; and a pair of first and second compartments separated by the cation exchange membrane, a method of separating carbon dioxide using a device comprising a first compartment located on the first electrode side and a second compartment located on the second electrode side. _: An agent that collects carbon dioxide in the common gas containing carbon dioxide in the second compartment where hydroxide ions are generated by applying a voltage so that the first electrode becomes the anode and the second electrode becomes the cathode, thereby generating carbonate ions or salts thereof. Level 1 ; and

Separation of carbon dioxide comprising a second step of applying a voltage so that the low ί 1 electrode becomes a cathode and the second electrode becomes an anode to reconvert the carbonate ion or salt thereof into carbon dioxide in a second compartment where hydrogen ions are generated. method.

【Claim 25】

The method of separating carbon dioxide according to claim 24, wherein a voltage of 0.42 V or more and 10 V or less is applied to the first and second electrodes.

【Claim 26】

The method of separating carbon dioxide according to claim 24, wherein the mixed gas contains carbon dioxide in an amount of 2% by volume or more.

【Claim 27】

The method of separating carbon dioxide according to claim 24, wherein in the first step, the second compartment contains carbonate, hydroxide, or a mixture thereof as an electrolyte.

【Claim 28】

The separation of carbon dioxide according to claim 24, wherein in the first step, when maintaining a constant value between pH 7 and 9 in the second compartment, a voltage is applied so that the first electrode becomes the cathode and the second electrode becomes the anode. method.

【Claim 29】

The method of claim 24, wherein when the pH of the first compartment becomes 0 to 3 in the first step, a voltage is applied so that the first electrode becomes a cathode and the second electrode becomes an anode.

【Claim 30】

The method of claim 24, wherein if the concentration of carbonate ions in the second compartment is greater than the saturation concentration in the first step, a voltage is applied so that the first electrode becomes the cathode and the second electrode becomes the anode.

[Claim 31]

The method of claim 24, wherein when the increase in electrical conductivity in the second compartment of the first step ranges from 10 mS/cm to 50 tnS/cm, a voltage is applied so that the first electrode becomes the cathode and the second electrode becomes the anode. ，Separation method of carbon dioxide.

【Claim 32】

The method of claim 24, wherein a voltage of 0.83 V to 2 V is applied to the first and second electrodes.

[Claim 33]

The method of separating carbon dioxide according to claim 24, wherein the mixed gas is brought into contact with water of pH 3.5 to 7 and then injected into the second compartment.

【Claim 34】

The method of claim 24, wherein in the second compartment of the first stage, the A carbon dioxide separation method that captures carbon dioxide in common gas to produce carbonate ions or salts thereof, and captures sulfur dioxide to produce sulfurous acid ions or salts thereof.

[Claim 35]

The method of claim 34, wherein in the second section of the second step, the carbonate ions or salts thereof are reconverted to carbon dioxide, and sulfate ions or salts thereof are generated from the sulfite ions or salts thereof.

[Claim 36]

The method of claim 35, wherein a voltage of 1.03 V to 2 V is applied to the first and second electrodes.

【Claim 37】

The method of claim 24, wherein step 1 is repeated again after the second step _.

,

【Claim 38】

The method of claim 24, wherein the second step captures carbon dioxide in the mixed gas containing carbon dioxide in the first compartment to produce carbonate ions or salts thereof.

[Claim 39]

The method of claim 24, wherein in the first step, the second compartment contains carbonate and hydroxide as the electrolyte and a mixture thereof, and in the second step, the first compartment contains carbonate and hydroxide as the electrolyte and a mixture thereof. Including, a method of separating carbon dioxide.

【Claim 40】

The method of claim 38, wherein carbonic acid or its salt is reconverted to carbon dioxide in the first section of the first step repeated after the second step.

[Claim 41]

25. The method of claim 24, wherein the device includes: a first electrode; second electrode; One bipolar film located between the first electrode and the second electrode; The first electrode and two cation exchange membranes positioned between the bipolar membrane and between the bipolar membrane and the second electrode; A device comprising two pairs of first and second compartments, each of which is separated by an exchange membrane, with two Crab 1 compartments located on the Crab 1 electrode side and two second compartments located on the Crab 2 electrode side. Method for separating carbon dioxide using .

【Claim 42】

25. The method of claim 24, wherein the device includes: a first electrode; Crab 2 electrode; two or more bipolar films positioned between the first electrode and the second electrode; three or more cation exchange membranes located between the first electrode and the bipolar membrane, between the bipolar membrane and the bipolar membrane, and between the bipolar membrane and the second electrode; Three or more pairs of first and second compartments, each of which is separated by a silver exchange membrane, including at least three first compartments located on the first electrode side and three or more second compartments located on the second electrode side. A method of separating carbon dioxide using a device that does this. 【Claim 43】

A system for separating carbon dioxide from a common gas containing carbon dioxide, comprising: a first electrode; Crab 2 electrode; a cation exchange membrane positioned between the first and second electrodes; A pair of first and second compartments separated by the cation exchange membrane, the first compartment located on the first electrode side and the second compartment located on the second electrode side; And a power supply device that applies a voltage so that the first electrode becomes an anode and the second electrode becomes a cathode, and then applies a voltage so that the first electrode becomes a cathode and the second electrode becomes an anode. Carbon dioxide separation comprising a power supply device. system.