Carbon dioxide gas neutralization treatment system and carbon dioxide gas neutralization treatment method

Abstract

Provided are a carbon dioxide gas neutralization treatment system and a carbon dioxide gas neutralization treatment method that are capable of directly reducing carbon dioxide on a large scale in an economical way. The carbon dioxide gas neutralization treatment system according to the present invention comprises an electrolysis unit, a carbon dioxide treatment unit, an acidic solution neutralization unit and a discharge unit. The electrolysis unit comprises an electrolytic solution, a cathode electrode, an anode electrode and a diaphragm, wherein the electrolytic solution is an aqueous solution containing sodium chloride. In the electrolysis unit, the electrolytic solution is electrolyzed. Thus, a basic first aqueous solution is generated on the cathode side of the electrolysis unit and an acidic second aqueous solution is generated on the anode side of the electrolysis unit. The carbon dioxide gas neutralization treatment system according to the present invention is characterized in that the specific energy consumption of the carbon dioxide absorption therein is at least greater than the specific energy consumption of the carbon dioxide discharge of a power generation system for the electricity used in the electrolysis unit.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide gas neutralization treatment system and a carbon dioxide gas neutralization treatment method. This application claims priority based on Japanese Patent Application No. 2021-038494 filed in Japan on March 10, 2021, and incorporates its content herein by reference.

Background Art

[0002] In accordance with the Paris Agreement, it is necessary to aim for substantially zero carbon dioxide emissions by 2050, but its realization is not easy. To achieve substantially zero carbon dioxide emissions, not only energy conservation and zero emissions, but also technologies for negative emissions of carbon dioxide are required. The amount of carbon dioxide emissions is enormous, and large-scale, economically rational, and realistic innovative technologies are demanded. Renewable energies such as solar power generation and wind power are the most expected, but their economic efficiency is still low, power storage is difficult, fluctuations are intense, and the operation rate is low, so their usage forms are limited. CCS (carbon dioxide geological storage) is a trump card for negative emissions, but its large-scale practical application also requires considerations such as environmental protection and is uncertain. DACCS (direct air capture of carbon dioxide) and BECCS (biomass CCS) also presuppose the realization of CCS. CCU (carbon capture and utilization) does not directly lead to negative emissions of carbon dioxide. The utilization of biomass is limited by the rate and efficiency of plant photosynthesis. Water electrolysis and electrochemical reduction of carbon dioxide using renewable power are also very costly and are not negative emissions themselves.

[0003] So far, the wisdom of the world has been gathered to address the issue of global warming, but at present, no decisive method has been found to achieve virtually zero carbon dioxide emissions. The difficulty of the carbon dioxide problem lies in the fact that partial optimal solutions alone cannot solve the problem for the entire planet. For example, behind the technology for carbon dioxide recovery and recycling, there may be a large amount of carbon dioxide emissions during the process or elsewhere, such as the need for a huge amount of hydrogen and electricity for separation, purification, and reduction. That is, it is necessary to consider whether a consistent total system can lead to carbon dioxide reduction and truly achieve zero emissions. In addition, when a method cannot be completed within a single country or region, it may be difficult to reach an agreement on cooperation.

[0004] As a technology for fixing carbon dioxide gas, there is weathering promotion using basic substances, especially basic minerals, through neutralization reactions. Looking at the whole world, the total amount of basic substances containing basic minerals is enormous, and it can sufficiently absorb the carbon dioxide generated from human social activities. However, it has the drawback that the rate of mineral weathering promotion is very slow. Even if only the solid surface becomes carbonate, it takes a considerable amount of time for neutralization to reach the bulk interior, and there is also a limit to refinement. Verifying the effectiveness of simple weathering promotion itself is difficult. Injecting carbon dioxide gas into the rock mass of basic minerals is almost similar to CCS, but the suitable location, treatment volume, and treatment speed are very limited.

[0005] To suppress the recent rapid increase in carbon dioxide gas, innovative technologies with immediate large-scale and economic rationality are required. Carbon dioxide reacts immediately with alkali metal hydroxides such as NaOH, but the use of NaOH at the reagent level is expensive. NaOH is produced with the generation of Cl 2 When carbon dioxide is reacted with NaOH on a large scale, there is a problem that a large amount of toxic and corrosive Cl 2 gas becomes surplus. It cannot be stored in a gaseous state. Cl 2 generates HClO when dissolved in water and is useful as a chemical in some disinfectants, etc., but when produced in large quantities, even at low concentrations, it has a great impact on the environment and cannot be discarded directly into the external environment. Hydrogen from the cathode side and Cl 2There is also a method of reacting to produce HCl, but it is necessary to consider including aspects that are disadvantageous in terms of power consumption and H 2 consumption. Also, if the power used for the electrolysis is from a thermal power plant that emits carbon dioxide, there may be contradictions such as an overall increase in carbon dioxide. If the power for electrolysis is from renewable energy, the power is expensive, and the electrolysis operation rate (equipment utilization rate) does not increase, further eliminating economic viability. The method of producing hydrogen by electrolyzing renewable energy has the dilemma that the cost of hydrogen production is high, and the hydrogen utilization infrastructure, including transportation and utilization, does not spread.

[0006] In the case of solar power generation, it is about 14% in Japan and about 20% even in the sunbelt region. In the case of wind power generation, it is about 20 - 30%. Therefore, continuous operation is difficult. There is also a method of combining with energy storage for continuous operation, but the cost increases. Even if the operation rate is low, if it operates only with renewable energy, the carbon dioxide emissions during operation can be seemingly very low, and negative emissions are also possible, but it is difficult to achieve economic viability. Even for negative emissions such as DACCS or the combination of solar power generation and water electrolysis, it is difficult to spread when the cost is very high. The problem of carbon dioxide global warming is now also an economic problem, and the compatibility between the two is very important.

[0007] The negative and positive emission technologies for carbon dioxide are not just in the sense of relative comparison, but the results obtained are completely different. Even if there is a little negative emission, by introducing it on a large scale, there is a possibility of significant carbon dioxide reduction. On the other hand, even if there is a little positive emission, by introducing it on a large scale, there will be a huge amount of carbon dioxide emissions. There is a need for an idea to increase the operation rate as much as possible and achieve negative emissions.

[0008] For example, Non-Patent Document 1 discloses the following method. Using a porous membrane as a diaphragm, Na 2 SO 4An aqueous solution is electrolyzed. At the cathode, hydrogen gas and an aqueous NaOH solution are generated. At the anode side, oxygen and sulfuric acid are generated from water, and a basic mineral is directly added to the anode tank for neutralization. Air is blown into the aqueous NaOH solution later to convert it to carbonate anions by neutralizing carbon dioxide in the air with NaOH.

[0009] Also, Patent Document 1 discloses the following method. In the electrolysis of sodium chloride, NaOH and HClO are generated. NaOH is considered as the valuable product to be produced. HClO is recovered as CaCl 2 via Ca(ClO) 2 to improve the economy.

[0010] Patent Documents 2 - 5 disclose the following method. In seawater electrolysis, NaOH is produced at as low a voltage as possible, carbon dioxide gas in the exhaust gas is converted to carbonate, and then reacted with HCl to recover pure carbon dioxide gas. As the product on the anode side, Cl 2 or H 2 generated on the cathode side is reacted to form HCl. A comparison is made with the methylamine recovery method for carbon dioxide gas. Also, for carbon dioxide emitted from a coal-fired power plant, seawater electrolysis is carried out, and the power consumption of pumps etc. for carbon dioxide recovery including carbon dioxide is calculated. It is estimated that the carbon dioxide recovery part will not result in carbon dioxide emissions (partial negative emissions).

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0012] [Non-Patent Document 1] Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production, PNAS, 18, 2013, 10095-10100; https: / / doi.org / 10.1073 / pnas.1222358110。 [Summary of the Invention] [Problems to be Solved by the Invention]

[0013] However, in the method of Non-Patent Document 1, due to the influence of the potential for hydrogen generation on the cathode side, the electrolysis voltage is as high as 3.5 V or more, and there is a drawback of high power consumption. With this experimental value, even if the power of LNG thermal power, which has less carbon dioxide emissions among thermal power generation, is used, the carbon dioxide emissions will actually increase. For the use of the raw material Na 2 SO 4 , although Cl 2 is not generated, it is inferior to sodium chloride in terms of reserves and economy. Although the concept of seawater utilization is mentioned, no specific method for converting it into acidic water is shown. Although the use of renewable energy power, which is not a fossil fuel, is assumed, no solution is presented for the problem that its operating rate cannot be increased. The conditions and assumptions for whether carbon dioxide is actually reduced are also unclear. In fact, due to poor voltage and current efficiency, carbon dioxide is not a negative emission experimentally.

[0014] Also, in Patent Document 1, in order to recover CaCl 2 with CaCO 3 , carbon dioxide is reacted with NaOH to obtain Na 2 CO 3and the Na 2 CO 3 and CaCl 2 This is a complex system in which they react. The overall objective is the positioning of a carbon dioxide recovery system, and no consideration is given to what to do with the recovered carbon dioxide (including the final treatment such as discharging it to the external environment). As a whole, the product balance does not match, and it does not achieve zero emissions or negative emissions including carbon dioxide emissions from thermal power plants.

[0015] In Patent Documents 2 - 5, in a system that only recovers carbon dioxide, no consideration is given to what to do with the recovered carbon dioxide, lacking consideration of what to do with it finally. At the same time, the overall product balance of HCl and Cl 2 that should be generated simultaneously does not match. Although the expression "mineral" is used, it clearly indicates the carbonate that precipitates when reacting NaOH with carbon dioxide, and there is no mention at all about the use of basic minerals and the like.

[0016] As described above, in a state of high operating rate, a method for realizing negative emissions of carbon dioxide is not disclosed for the entire system, including not only the recovery of carbon dioxide gas but also the neutralization treatment of carbon dioxide gas to the external environment.

[0017] The present invention aims to solve the above - mentioned problems, and an object of the present invention is to provide a technology of an integrated system that enables long - term immobilization of carbon dioxide gas, which is the cause of global warming. It provides an innovative and highly economical negative emission technology that contributes to the goal of the Paris Agreement and the Japanese government to achieve substantially zero carbon dioxide emissions by 2050. Further, in one embodiment of the present invention, it is a technology particularly for an essential carbon dioxide absorption promotion treatment using a neutralization reaction of basic minerals.

[0018] The inventor, as a method for simultaneously solving many problems regarding negative emission technologies that utilize the above neutralization reaction, considered various technology combination patterns and operations, conducted economic and LCA calculations, and developed the most realistic carbon dioxide reduction system while taking into account the purity of the generated acidic and basic aqueous solutions. Even if the purity is low, there is no problem. The method of the present invention is a technology that is easy to be self - contained in one country or region. It has been clarified that a certain method is implemented under certain conditions, which can contribute to the realization of a negative emission system.

Means for Solving the Problems

[0019] The present invention has been completed based on these findings, and specifically has the following features. [1] A neutralization treatment system for carbon dioxide gas, comprising an electrolysis device, a carbon dioxide treatment device, an acidic liquid neutralization device, and a discharge device, wherein the electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, the electrolytic solution is an aqueous solution containing sodium chloride, in the electrolysis device, the electrolytic solution is electrolyzed, and a basic first aqueous solution is generated on the cathode side of the electrolysis device, and an acidic second aqueous solution is generated on the anode side of the electrolysis device, in the carbon dioxide treatment device, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions, in the acidic liquid neutralization device, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution, the discharge device has a first discharge part and a second discharge part, the first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment, the second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment, A neutralization treatment system for carbon dioxide gas, characterized in that the energy unit of carbon dioxide absorption is larger than at least the energy unit of carbon dioxide emissions of the power generation facility using the power consumed by the electrolysis device. 〔2〕 The energy unit of the carbon dioxide absorption is 0.5 kg-CO 2 / kWh or more, and the carbon dioxide gas neutralization treatment system according to 〔1〕. 〔3〕 In the acidic liquid neutralization device, the basic substance for neutralizing the second aqueous solution contains a basic mineral or a basic waste, and the carbon dioxide gas neutralization treatment system according to 〔1〕 or 〔2〕. 〔4〕 In the carbon dioxide treatment device, on the cathode side, the first aqueous solution and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution is discharged to the external environment, or the carbon dioxide treatment device includes a first storage section, the first aqueous solution is transferred from the cathode side to the first storage section, and in the first storage section, the first aqueous solution and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution is discharged to the external environment. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕 to 〔3〕. 〔5〕 The electrolysis device uses the electric power including thermal power generation, and the electrolysis device is continuously operated to neutralize carbon dioxide. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕 to 〔4〕. 〔6〕 In the electrolysis device, the operating rate of electrolysis is 20% or more. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕 to 〔5〕. 〔7〕 The acidic liquid neutralization device includes a second storage section, the second aqueous solution generated on the anode side is transferred to the second storage section, and in the second storage section, the second aqueous solution is neutralized with the basic substance, and the neutralized aqueous solution is discharged to the external environment. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕 to 〔6〕. 〔8〕 When the electrolysis voltage is X and the energy unit of the carbon dioxide emission of the power generation facility is A, the relationship between the electrolysis voltage, the current efficiency Q, and the energy unit of the carbon dioxide emission is represented by the following formula (1). The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔7〕. 1.64×Q / X > A (1) (In the formula, the unit of X is V, and the unit of A is kg-CO 2 / kWh.) 〔9〕 When the electrolysis voltage is X, the energy efficiency of carbon dioxide emission by auxiliary equipment other than electrolysis and the neutralization introduction of basic substances is Z, the overall carbon dioxide energy efficiency of the system is CEE, and the energy unit of the carbon dioxide emission of the power generation facility for the power used in electrolysis is A, the relationship is represented by the following formula (4). The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔8〕. CEE = (X / 1.64×Q) + Z < (1 / A) (4) (In the formula, the unit of X is V, and the units of Z and A are kg-CO 2 / kWh.) 〔10〕 The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔9〕, wherein the diaphragm is an ion exchange membrane. 〔11〕 Further, it includes an oxygen reduction device, On the cathode side of the electrolysis device, using the oxygen reduction device, a gas containing oxygen is supplied for oxygen reduction. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔10〕. 〔12〕 In the electrolysis device, the carbon dioxide supplied from the carbon dioxide treatment device is brought into contact with the aqueous solution on the cathode side to generate bicarbonate ions. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔11〕. 〔13〕 Further, it includes a sensor, The sensor has a first sensor for monitoring the pH or a second sensor for monitoring the composition of the dissolved matter to neutralize the second aqueous solution. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔12〕. 〔14〕The second storage section has two or more storage sub - sections, the two or more storage sub - sections are connected in two or more stages in the order of acid concentration, and for the two or more storage sub - sections, devices for adding a basic substance are connected in two or more stages. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔13〕. 〔15〕The ion exchange membrane is disposed on the surface of the anode electrode or in the vicinity of the anode electrode. The carbon dioxide gas neutralization treatment system according to any one of 〔1〕~〔14〕. 〔16〕Using the oxygen reduction device, high - purity oxygen generated on the anode side is sent to the cathode side. The carbon dioxide gas neutralization treatment system according to any one of 〔11〕~〔15〕. 〔17〕High - purity oxygen generated on the anode side is sent to a thermal power generation facility. The carbon dioxide gas neutralization treatment system according to any one of claims 1~16. 〔18〕The basic mineral or basic waste contains Fe 2+ , V 4+ , Mn 2+ . The basic mineral or basic waste is dissolved in the second aqueous solution of the second storage section, and an oxidized compound of by - produced Cl - is brought into contact with the dissolved aqueous solution and reduced to be converted into HCl. The carbon dioxide gas neutralization treatment system according to any one of 〔7〕~〔17〕. 〔19〕The basic mineral or basic waste is an R substance, the R substance is a substance containing an R mineral, steel slag other than the R mineral, or cement waste material other than the R mineral, the R substance is dissolved in the second aqueous solution of the second storage section, substances that deteriorate the electrolytic reaction are removed, and then a solution containing ions of Fe 2+ , V 4+ , Mn 2+ as R elements is introduced to the anode side of the electrolysis device to reduce the electrolytic voltage. The carbon dioxide gas neutralization treatment system according to any one of 〔7〕~〔18〕. 〔20〕A method for neutralizing carbon dioxide gas, comprising an electrolysis step, a carbon dioxide treatment step, an acidic solution neutralization step, and a discharge step, wherein the electrolysis step uses an electrolysis device having an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, the electrolytic solution is an aqueous solution containing sodium chloride, in the electrolysis step, the electrolytic solution is electrolyzed to generate a basic first aqueous solution on the cathode side of the electrolysis device and an acidic second aqueous solution on the anode side of the electrolysis device, in the carbon dioxide treatment step, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions, in the acidic solution neutralization step, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution, the discharge step has a first discharge sub-step and a second discharge sub-step in the first discharge sub-step, the first aqueous solution or the third aqueous solution is discharged to the external environment, and in the second discharge sub-step, the second aqueous solution or the fourth aqueous solution is discharged to the external environment, and the energy unit of carbon dioxide absorption is characterized in that it is larger than at least the energy unit of carbon dioxide emission of the power generation facility using the power in the electrolysis step. A method for neutralizing carbon dioxide gas.

Effect of the Invention

[0020] According to the present invention, a carbon dioxide gas neutralization treatment system can be formed in which the energy unit of carbon dioxide absorption is larger than the energy unit of carbon dioxide emission of the power generation facility using the power in the electrolysis device. It has been found that the practicality of negative emissions with economic efficiency can be improved compared to the prior art.

[0021] In addition, the inventors have found that in one embodiment of the above-described combination system, economic rationality can be improved, such as a decrease in electrolysis voltage or suppression of side reactions. Although a countermeasure system for the carbon dioxide problem often results in an increase in carbon dioxide emissions as the processes are combined more complexly, the inventors have found that there are optimal conditions for negative emission operation in the present invention.

Brief Description of the Drawings

[0022]

Figure 1

Modes for Carrying Out the Invention

[0023] Hereinafter, a carbon dioxide gas neutralization treatment system according to an embodiment of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0024] (Explanation of Terms) Current efficiency (Q), also called Faraday efficiency, indicates the ratio or selectivity of the electrons used for the target reaction to the number of electrons that have flowed. The target reaction in the electrolysis of the present invention is the production ratio of base (OH - ions). It is usually expressed as a ratio number or percentage between 0 and 1. Before the neutralization reaction, the concentration of the base generated by electrolysis can be evaluated by measuring the pH. When an undesirable reaction occurs during the reaction, the current efficiency decreases. For example, when an acid and a base are mixed halfway, the current efficiency of base generation decreases.

[0025] The energy unit of carbon dioxide emissions is a value representing energy efficiency, which is the amount of carbon dioxide emitted by consuming energy such as electric power and heat (fuel) required to produce a unit amount of product or amount, and is also called the carbon dioxide emission coefficient. In the case of a power plant, for example, it is expressed in units of kg-CO 2 / kWh.

[0026] The energy unit of carbon dioxide absorption is a value representing the energy efficiency in carbon dioxide absorption, which refers to the amount of carbon dioxide absorbed by consuming a unit amount of energy such as electric power. The unit is expressed in kg-CO 2 / kWh. Contrary to the energy unit of carbon dioxide emission, the energy unit of carbon dioxide absorption is a concept corresponding to negative emission technologies such as the present invention that consume electric power to absorb carbon dioxide.

[0027] (Carbon Dioxide Gas Neutralization Treatment System) As shown in FIG. 1, the carbon dioxide gas neutralization treatment system according to an embodiment of the present invention includes an electrolysis device, a carbon dioxide treatment device, an acidic liquid neutralization device, and a discharge device. The electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, and the electrolytic solution is an aqueous solution containing sodium chloride. Electrolyze the electrolytic solution in the electrolysis device to generate a basic first aqueous solution on the cathode side of the electrolysis device, and generate an acidic second aqueous solution on the anode side of the electrolysis device. In the carbon dioxide treatment device, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions. In the acidic liquid neutralization device, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution. The discharge device has a first discharge part and a second discharge part. The first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment, and the second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment. The carbon dioxide gas neutralization treatment system of this embodiment is characterized in that the energy unit of carbon dioxide absorption is at least greater than the energy unit of carbon dioxide emission of the power generation facility using the electric power used in at least the electrolysis device. It is preferable that the energy unit of carbon dioxide absorption is 0.5 kg-CO 2 / kWh or more, and more preferably 0.8 kg-CO 2 / kWh or more.

[0028] In this embodiment, a method is provided that enables negative emissions even when a thermal power plant operates at its rated output continuously as a power source. The continuous operation of the electrolyzer means that, except during maintenance periods, the operation is continued as close to the rated value as possible for as long as possible, thereby improving economic efficiency. It can be adjusted by thermal power generation or the like to smooth out variable renewable energies such as solar power generation and wind power generation. In recent years, variable renewable energies such as solar power generation and wind power generation have imposed loads on the grid, but this can be alleviated.

[0029] <Electrolyzer> The electrolyzer of this embodiment comprises an electrolytic solution, a diaphragm, a cathode electrode, and an anode electrode. The electrolytic solution includes an anode electrolytic solution and a cathode electrolytic solution. The diaphragm separates the anode electrolytic solution and the cathode electrolytic solution of the electrolyzer. As the diaphragm according to this embodiment, an ion exchange membrane or a porous membrane can be used, etc., but an ion exchange membrane is preferred for improving electrolysis efficiency and carbon dioxide neutralization efficiency. In particular, a cation exchange membrane that permeates alkali metal ions and further a selective permeation membrane for monovalent cations are preferably used between the cathode side. If there is unexpected movement of electrons or ions, the current that flows will not be used for acid-base generation, and the current efficiency will decrease. When using a porous membrane, in order to prevent unfavorable ion flow, for example, it is necessary to devise a one-way water flow so that the basic aqueous solution does not mix with the acidic aqueous solution. Also, arranging an anion exchange membrane on the anode side is also preferable for improving current efficiency. A bipolar membrane can also be used, which has the advantage of simplicity in the whole, but requires measures to prevent the voltage from increasing. The current efficiency is preferably at least 70% or more, more preferably 90% or more, and even more preferably close to 100%.

[0030] <Power source> The power source of the carbon dioxide gas neutralization treatment system of this embodiment is not particularly limited, and examples include a thermal power plant that generates carbon dioxide gas. Since thermal power plants use fossil resources such as coal, oil, and natural gas as raw materials, there is a problem of emitting a huge amount of carbon dioxide. Thermal power plants can also vary their output, but operating at a continuous rated output is more efficient and improves economic efficiency.

[0031] <Electrolyte solution> For the aqueous solution containing sodium chloride, which is the electrolyte solution according to this embodiment, seawater or brine can be used. The same raw material purification technology as that in the conventional chlor-alkali process electrolysis using seawater can be used. The electrolyte concentration is 0.1 M or more, preferably 0.5 M or more, more preferably 1 M or more or the saturation concentration of the salt, in order to reduce the resistance. Since the concentration is preferably as high as possible within the dissolving range, 5 M or more is even more preferable.

[0032] <Carbon dioxide treatment device> In the carbon dioxide treatment device according to this embodiment, on the cathode side of the electrolysis device, the first aqueous solution and carbon dioxide gas may be subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution may be discharged to the external environment. Alternatively, the carbon dioxide treatment device may include a first storage section, the first aqueous solution may be transferred from the cathode side to the first storage section, and in the first storage section, the first aqueous solution and carbon dioxide gas may be subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution may be discharged to the external environment. When the electrolysis device uses the power of a thermal power plant, from the viewpoint that the electrolysis device can be continuously operated to neutralize carbon dioxide, in the carbon dioxide treatment device according to this embodiment, it is preferable to carry out the neutralization dissolution reaction on the cathode side of the electrolysis device to generate the third aqueous solution.

[0033] The third aqueous solution generated by the neutralization dissolution reaction of the basic first aqueous solution and carbon dioxide gas contains an anion of carbonic acid. The anion of carbonic acid refers to HCO 3 - or CO 3 2- but formally, it may be dissolved in water as H 2 CO 3 The OH - of the basic first aqueous solution and carbon dioxide gas are neutralized to form HCO 3 - and CO 3 2-It changes to. When discharging the third aqueous solution to the external environment, it is preferable that the third aqueous solution is neutral. HCO 3 - and CO 3 2- The ratio of is determined by pH, and the more neutral it is, the more HCO 3 - becomes more. Also, the carbon dioxide gas neutralization treatment system of the present invention preferably further includes a sensor, and this sensor may have a first sensor for monitoring pH or a second sensor for monitoring the composition of the dissolved matter. It is preferable to monitor the pH and composition of the third aqueous solution appropriately with a sensor or the like. Also, when discharging the third aqueous solution to the external environment, it may be stored in a management pond without flowing it into the sea or lake, or the aqueous solution may be evaporated and stored as a solid of bicarbonate.

[0034] When carbon dioxide is brought into contact with the first aqueous solution on the cathode side of electrolysis to generate bicarbonate ions, if the pH is immediately neutralized and the pH becomes close to neutral, the electrolysis voltage can be significantly reduced compared to the highly alkaline pH = 14. However, some impurity removal is required so that carbon dioxide does not contaminate the cathode electrode. Ultra-high purification is not necessary, and it is sufficient to have a water scrubber or water bubbling level, so the energy consumption loss can be reduced. When contacting with a high-concentration aqueous solution close to neutral NaHCO 3 The neutralized downstream NaHCO 3 aqueous solution can also be circulated and returned to the aqueous solution on the cathode side of electrolysis.

[0035] In the combination of a method of feeding carbon dioxide gas near the cathode electrode and a gas diffusion electrode, since carbonates may precipitate on the electrode, it is desirable to take measures such as flushing with brine. In the present invention, since there is little need to make the alkaline aqueous solution highly pure and highly concentrated, a method of flushing with water, brine, an NaOH aqueous solution, etc. is effective. Also, by introducing brine to the cathode electrode side, the electrical conductivity of the cathode cell can be increased. In general NaOH production, thin NaOH is introduced for purity improvement, but due to its low concentration, the initial conductivity is poor and it causes an increase in voltage. On the other hand, in the present invention, there is no problem even if raw salts such as sodium chloride are mixed in NaOH, and the initial electrolyte concentration and its electrical conductivity can be improved.

[0036] <Acidic liquid neutralization device> In the present embodiment, it is preferable that the basic substance that neutralizes the second aqueous solution generated on the anode side to generate a fourth aqueous solution contains a basic mineral or a basic waste.

[0037] A basic mineral is a mineral that shows alkalinity when put in water. It often contains many elements of Groups 1 to 3 of the periodic table. It is represented by ultra-basic rocks, basic rocks, kanran rocks, basalts, etc. Most of the basic minerals have their surfaces stabilized by carbonate ions, etc. Minerals containing carbonate ions such as limestone can also be used, but since carbon dioxide may be generated by neutralization, it is desirable that the carbonate ion content be low.

[0038] In the neutralization of the acidic second aqueous solution with a basic mineral, since the neutralization rate becomes faster when the basic mineral is pulverized, it is preferable to make the basic mineral fine. On the other hand, it is necessary to avoid consuming a large amount of pulverization energy. If the pH is low, the neutralization rate becomes faster. Neutralization can be advanced by taking a longer retention time. If it takes a long time, neutralization can be carried out by standing in cracks in the formation of the basic mineral, open-pit mining holes, or reservoir-like storage compartments. Natural neutralization takes time, but the energy loss and cost are small.

[0039] Basic waste refers to basic substances such as basic minerals, steel slag, and cement-related waste, and these can be mixed and used for neutralization with HCl.

[0040] "Second storage section" It is preferable that the acidic liquid neutralization device according to this embodiment includes a second storage section. It is preferable to transfer the basic second aqueous solution generated on the anode side to the second storage section. Examples of the transfer means include pipelines and the like. In the second storage section, the second aqueous solution can be neutralized with the basic substance, and the neutralized aqueous solution can be discharged to the external environment.

[0041] It is preferable that the second storage section has two or more storage sub-sections. The two or more storage sub-sections may be connected in two or more multi-stages in the order of acid concentration, or for the two or more storage sub-sections, devices for adding basic substances may be connected in two or more multi-stages. By multi-staging the storage section, in order to finally discharge to the environment, while monitoring the pH and composition, the types and amounts of basic minerals can be introduced in multiple stages to control the neutralization conditions.

[0042] In a place where the pH of the pre-stage storage sub-section of the storage section is very low, the dissolution rate of minerals is fast, and it can be industrially used for extraction of high-value substances from minerals and generation of reducing ions such as Fe 2+ etc. It is desirable to avoid using minerals containing a large amount of carbonate ions. Since the solution is warm due to Joule heat in the pre-stage, it is suitable for mineral dissolution.

[0043] In the post-stage storage sub-section of the storage section, control and management for discharging to the environment are performed. Minerals containing a large amount of carbonate ions such as limestone can also be used in the post-stage without generating carbon dioxide. Near neutrality, ions such as Fe 2+ etc. precipitate. The final fine adjustment of pH is performed by appropriately mixing the acidic solution on the cathode side.

[0044] "Selectivity of anode electrolysis products" On the anode side, O due to the oxidation of water 2Generate, or perform a reaction to generate chlorine (Cl - ) or a chloric acid compound (HClO 2 ) by oxidation of chloride ions (Cl x ) in seawater (brine). The generation of chlorine (Cl 2 ) is the same as the conventional chlor-alkali process in seawater. As the electrode for the reaction via Cl 2 , a DSA electrode coated with a platinum group such as ruthenium oxide or iridium oxide on a titanium substrate is desirable. Cl 2 can be used industrially as usual for useful chemicals such as vinyl chloride. Hypochlorous acid (HClO) can be used for sterilization, disinfection, bleaching, etc. Other HCl and HClO 2 , HClO 3 , HClO 4 can also be sold as various chemicals. On the other hand, when performing large-scale carbon dioxide treatment on the cathode side, such various chloric acid compounds are expected to become surplus in the future. The surplus HCl and chlorine compounds are either simply stored in a storage compartment or the like, or are detoxified or neutralized and discharged to the external environment.

[0045] When oxidizing seawater to generate oxygen, acidic water of HCl is generated, and when oxidizing sulfate to generate oxygen, acidic water of sulfuric acid is generated. When containing Cl - like seawater, the oxidation of water and the oxidation of Cl - become competitive reactions. In the conventional chlor-alkali process in seawater, the generation of Cl 2 is the main rather than the generation of O 2 . When detoxifying or neutralizing and discharging to the external environment in the use of seawater or brine containing Cl - , finally, the forms of oxygen generation and HCl generation are desirable.

[0046] There are several methods for selectively generating O 2 using seawater. Use an electrode catalyst with a high overvoltage for the oxidation of Cl - . For example, use an electrode catalyst such as manganese oxide or Zn-doped RuO 2 . Also, a method of introducing an anion with a buffering action into the anolyte is effective.

[0047] Cl on or near the surface of the anode electrode - It is preferable to place a membrane with a negative charge to keep the protons away from the membrane. For example, a method of placing a cation exchange resin or a membrane with a cationic substituent is very effective. The cation exchange resin is made into a cylindrical or enclosure shape, and high-concentration stable acid water is placed inside. For example, sulfuric acid, perchloric acid, phosphoric acid, nitric acid, etc. High-purity oxygen is generated from the top of the enclosure. The generated protons move out from the cation exchange resin. Water is supplied to the enclosure. Placing many membranes helps to improve current efficiency and reaction selectivity, but the current-voltage characteristics may decrease due to increased electrical resistance, so a balance must be considered. It is important that the current efficiency is improved even at the expense of voltage and power, and as a result, the energy consumption rate of carbon dioxide absorption is improved. It is desirable that the membranes are as thin as possible and the spacing between them is narrow so as not to deteriorate the electrical resistance.

[0048] <Management of the acidic second aqueous solution> The second acidic aqueous solution is preferably simply stored in a second storage compartment, or is detoxified or neutralized before being discharged to the external environment. Examples of the second storage compartment include a storage management pond, a storage tank, a storage facility, a natural depression or a crack, etc. When discharging to the external environment, the second aqueous solution may be stored in a management pond or may be evaporated to be stored as a solid metal salt, without being discharged into the sea or a lake.

[0049] When storing volatile chlorine compounds, be mindful of the environment by using covers to prevent evaporation. Also, be careful of unexpected cracks in the rock. The extraction process known as leaching in mines can be used as a reference for managing this, and can be used for neutralization. This method takes longer than the latter method below, but consumes less energy.

[0050] Tank leaching (crushing high-grade ore into slurry and performing stirring leaching in a tank), vat leaching (crushing ore, depositing it in a large container, and immersing it in a liquid for leaching), heap leaching (crushing ore, depositing it on an impermeable base (including a sheet), and spraying a liquid for leaching), dump leaching (depositing low-grade Run-of-Mine Ore and waste rock and directly spraying a liquid for leaching), in-situ leaching (creating cracks at the original location without moving the ore and performing leaching at that location). If the production rate of acidic water and the neutralization time are not balanced, respond by making the crushing finer or increasing the neutralization contact time in the storage section. Considering energy efficiency, the latter is preferred.

[0051] "Reduce Cl with R mineral to HCl" 2 "to HCl" In this embodiment, it is preferable that the basic mineral or basic waste contains Fe 2+ , V 4+ , Mn 2+ etc. In the second aqueous solution of the second storage section, dissolve such a basic mineral or basic waste, and preferably contact the oxidized compound of the by-produced Cl - with its dissolved aqueous solution for reduction to convert it to HCl. As a method for reducing the toxic and difficult-to-store Cl 2 to HCl for detoxification, there is a reaction of reducing Cl 2 with hydrogen generated on the cathode electrode side. However, hydrogen is essential and leads to energy loss. Hydrogen generation has a higher electrolysis voltage than oxygen reduction, increasing power energy consumption. As a method that does not use hydrogen, for example, a reaction using minerals can be used in the present invention. Basic minerals often contain reduced ions (reductants) of stable oxides such as Fe 2+ (in the case of iron, Fe 3+ ). FeSiO 3 is a representative example. When a mineral containing this reductant (R mineral. R is the initial letter of Reduction) is dissolved in the acidic HCl aqueous solution of the second storage section, a solution containing reductants such as Fe 2+ ions is formed. This Fe 2+ and Cl 2When reacted, it can be converted into Fe 3+ and hydrochloric acid. By incorporating this reaction into the system, oxygen reduction is actively carried out at the cathode, leading to a reduction in voltage. Since existing chlor-alkali process technologies can be used, it is possible to bypass and avoid the new development of selective oxygen generation from seawater, and the merit of reducing the energy loss in that part is significant.

[0052] Fe 2+ In addition to this, reductants of reactions with a redox potential more negative than +1.3 V (RHE), such as V 5+ / V 4+ and Mn 4+ / Mn 2+ etc. can be used. Without dissolving the R mineral, it is also possible to react with Cl 2 by a thermal reaction to produce HCl. In addition to the R mineral, it is also possible to mix and use substances containing reductants such as steel slag and cement waste. In the present invention, substances containing R mineral, steel slag other than R mineral, or cement waste other than R mineral are collectively referred to as R substances.

[0053] "Putting the reductant ions of the dissolved R substance into the anode to lower the voltage" Dissolving the R substance in the acidic aqueous solution of the second storage compartment and introducing the solution containing its reductant ions (for example, Fe 2+ , V 4+ , Mn 2+ etc.) to the anode side of the electrolysis device to lower the electrolysis voltage is an effective method. In that case, it is preferable to remove substances that deteriorate the electrolysis reaction and then introduce the aqueous solution to the anode side of the electrolysis device. Cations such as Fe 2+ can come into contact even if a cation exchange membrane is installed on the anode electrode.

[0054] "Other methods for reducing voltage" As other methods for reducing the electrolysis voltage, Fe by photocatalyst 2+There is a combination with the method of sending the solution of the patent for low-voltage NaOH production by generation (Patent No. 6345524) to the anode. By combining this technology with the proposed patent specification, it can be used for further reduction of voltage. However, since Patent No. 6345524 is not for the purpose of negative emission like this proposal, the combination method of the system and the operating conditions are very different, and it is also different in that concepts such as neutralization by basic minerals and O 2 reduction are not included. It should be stated that they are different in this respect.

[0055] Also, as the anode electrode, the method of using a semiconductor photoelectrode can also be utilized. As the semiconductor, oxides such as BiVO 4 and nitrides and oxynitrides such as Ta 3 N 5 etc. can be used, but in particular, strongly acidic WO 3 etc. can be utilized. In the form of a sheet, a selective generation promoter is supported on the oxidation surface, and a reduction promoter is supported on the reduction surface, so that it can be made into a self-supporting type without an external bias. For the surface separating oxidation and reduction, a structure with porosity or filling the holes with a cation exchange membrane is good. 2 Selective generation promoter is supported on the oxidation surface, and 2 Reduction promoter is supported on the reduction surface, so that it can be made into a self-supporting type without an external bias. For the surface separating oxidation and reduction, a structure with porosity or filling the holes with a cation exchange membrane is good. Fe 2+ When ions coexist, Fe - oxidation occurs preferentially over Cl 2+ oxidation. It is preferable to install an ion exchange membrane on the surface of the anode electrode or in the vicinity of the anode electrode to suppress the outflow of iron ions.

[0056] This method can utilize various redox media other than Fe 3+ / Fe 2+ The range of the redox level is 0 V to +2 V (RHE), more preferably +0.2 V to 1.3 V (RHE). There are Fe 3+ / Fe 2+ 、V 5+ / V 4+ 、Mn 4+ / Mn 2+ 、iodine redox, nitrate redox, etc.

[0057] (Calculation of the energy unit of carbon dioxide emissions) In the carbon dioxide neutralization treatment system according to the present embodiment, as the power for electrolysis, the operation including renewable power and the power of a thermal power plant that emits carbon dioxide using fossil fuels can improve the practicality. Therefore, it is preferable that the power for electrolysis includes renewable power and the power of a thermal power plant that emits carbon dioxide using fossil fuels. The drawback of renewable power with large fluctuations and an inoperable operating rate can be compensated by using it in combination with the power of a thermal power plant or the like. Regarding this system that recovers carbon dioxide while emitting carbon dioxide, an LCA (Life Cycle Assessment) analysis was performed, and it was found that even if the thermal power generation is 100%, it can sufficiently contribute to negative emissions without contradiction. The higher the renewable energy ratio, the more carbon dioxide emissions are reduced, but it is a technology that can gradually increase the ratio of renewable power without difficulty.

[0058] In the carbon dioxide neutralization treatment system according to the present embodiment, the energy unit of carbon dioxide absorption can be calculated as follows. By operating for a long time, the carbon dioxide emissions related to the manufacture of the system can be ignored as much as possible. The energy consumption during long-term operation is very important. The largest energy consumption part is the electrolysis power. In the present invention, when the current efficiency generated by the basic aqueous solution for electrolysis is Q, and the energy unit of carbon dioxide emissions of the power generation facility for the power used in the electrolysis is A [kg-CO 2 / kWh], it was shown that at least the condition related to the electrolysis voltage X [V] is represented by the following formula (1).

[0059] 1.64×Q / X >A (1)

[0060] (Note that the left side indicates the energy unit of carbon dioxide absorption during electrolysis [kg-CO 2 / kWh]. Also, the calculation method for calculating the coefficient of 1.64 is as follows. (1000Wh×3600 seconds×M)÷(F×1000g)=1.64 (1-1) M is the mass number of carbon dioxide, 44, and F is the Faraday constant (96500).) Furthermore, the relationship between the current efficiency Q, which is a ratio, and the voltage V is incorporated. With this, the left side of Equation (1) becomes [kg-CO 2 / kWh].)

[0061] There is a relational expression stating that at least the left side must be greater than the right side A.

[0062] On the other hand, when using the energy per unit amount of carbon dioxide, that is, the carbon dioxide energy efficiency (CEE. The energy part is converted in kWh) [kWh / kg-CO 2 , it is expressed as the reciprocal of Equation (1) to obtain Equation (2). Let the electrolysis voltage be X [V] and the carbon dioxide energy efficiency of the entire system [kWh / kg-CO 2 be on the left side, and the energy unit of carbon dioxide emissions of the power generation facility using the power for electrolysis be A [kg-CO 2 / kWh] in this case.

[0063] (X / (1.64×Q)) < (1 / A) (2)

[0064] Both the right side and the left side are [kWh / kg-CO 2 . The left side is the energy required per unit amount of carbon dioxide in electrolysis. There is a relational expression stating that at least the left side must be smaller than the right side.

[0065] "Consideration of Auxiliary Equipment Energy Consumption" When compared with the electrolysis power used in the electrolysis device according to this embodiment, the energy consumption of auxiliary equipment such as auxiliary devices that assist the electrolysis device is small, and conversely, it is important to operate in such a way that the consumption of auxiliary equipment is reduced.

[0066] Examples of energy consumption other than the main electrolysis power (such as energy consumption of auxiliary equipment) include the following. When the energy consumption of auxiliary equipment cannot be ignored, correction is necessary. By this correction, the operating conditions can be further restricted compared to Equation (1).

[0067] (a) Removal of impurities and liquid feeding of brine or seawater. (a) Cathode - side operation: Neutralization of carbon dioxide gas from a power plant with a basic aqueous solution. Removal of impurities from carbon dioxide. Increased contact between carbon dioxide and NaOH. Neutralized NaHCO 3 Management and discharge of the aqueous solution. (c) In the case of oxygen reduction, supply air. (d) Fan power for capturing atmospheric carbon dioxide by DAC. (e) Anode - side operation: Liquid feeding, management, and discharge of acidic water. (f) Crushing and introduction of basic minerals.

[0068] The above (a) - (f) are much smaller compared to the energy of electrolysis. The fan power for DAC is about 2% of the electrolysis power at 2V electrolysis. The water supply power, estimated from the water pump characteristics, is about 0.2% of the electrolysis power per unit at 2V electrolysis. Even if the number of pumps is increased or the treatment concentration is decreased, it remains at the level of a few percent. Regarding basic minerals, in methods such as creating cracks in the original location without moving the ore and neutralizing at that location, the energy consumption can be ignored. Regarding crushing, if dynamite crushing is mainly used, the energy consumption and carbon dioxide emissions can be reduced. Removal of various impurities can be energy - saving through basic filter management.

[0069] Based on the sum of the energy consumption of auxiliary machines other than the above - mentioned electrolysis power and the carbon dioxide emissions from the introduction of basic substances, converting this into the unit of kg - CO 2 / kWh (Y [kg - CO 2 / kWh]), Equation (1) can be transformed. For example, Y can be calculated as an average value over a certain period such as a year. The items included in Y can be either variables or constants when the voltage V changes.

[0070] (1.64×Q / X)―Y > A (3) The above Equation (1) and Equation (2) must be satisfied at a minimum, and preferably Equation (3) is satisfied.

[0071] On the other hand, the carbon dioxide energy efficiency (CEE) [kWh / kg - CO 2When stacking, it becomes Equation (4). Z represents the carbon dioxide emissions from auxiliary equipment other than electrolysis power and energy consumption due to the introduction of basic substances as CEE [kWh / kg-CO 2 is represented by.

[0072] CEE = (X / 1.64×Q)+Z < (1 / A) (4)

[0073] Carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 Using a detailed calculation of Z, the energy consumption of various processes is accumulated. These are preferably small numbers. For example, regarding crushing, if dynamite crushing is mainly used, the energy consumption and carbon dioxide emissions can be reduced. However, referring to Non-Patent Document 2 (Nature, 583, 2020, pages 242-248), in Equation (4), Z can be estimated to be about 0.0153 kWh / kg-CO 2 and can be made quite small, so this condition can be satisfied. The Z of seawater pump power is about 0.002 kWh / kg-CO 2 per unit, and at the level of several units, it is within the error range. The fan power for carbon dioxide absorption is about 0.04 kWh / kg-CO 2 per unit, and at the level of several units, it is also within the error range. It is for system building security, lighting, etc., and is much smaller than the energy of electrolysis, etc., so it can be ignored. Conversely, this equation gives an important pointer regarding how much the carbon dioxide emissions of auxiliary equipment other than electrolysis should be suppressed and how many units of pumps, etc., should be used. There is a range of negative emissions for which this inequality holds, and operation within that range is fully possible.

[0074] "Concept of hybrid power" In the carbon dioxide gas neutralization treatment system of this embodiment, while there are conditions under which 100% thermal power generation can be achieved, since thermal power generation is not 100% and the higher the proportion of renewable energy, the greater the reduction in carbon dioxide emissions, it is a technology that can gradually increase the proportion of renewable power without difficulty. While using renewable power, the operating rate of the system of the present invention can be close to 100%. For example, in the "hybrid power" of thermal power generation and solar power generation, the energy unit of carbon dioxide emissions at the mixing ratio (MP and MP': values from 0 to 1) is as shown in the following formula (5). When using grid power, there are regional differences, but in many cases, it is hybrid power.

[0075] Energy unit of carbon dioxide emissions in hybrid power = Energy unit of carbon dioxide emissions in thermal power generation × Mixing ratio MP + Energy unit of carbon dioxide emissions in solar power generation × Mixing ratio MP' (5)

[0076] <Oxygen reduction device> The carbon dioxide gas neutralization treatment system of this embodiment preferably further includes an oxygen reduction device. It is preferable to supply a gas containing oxygen and perform oxygen reduction using the oxygen reduction device on the cathode side of the electrolysis device. For example, using an oxygen reduction device, air can be sent to the cathode side to perform oxygen reduction at the cathode. Also, using an oxygen reduction device, the high-purity oxygen generated on the anode side can be collected, and the collected high-purity oxygen can be circulated to the cathode side. Moreover, by sending the high-purity oxygen generated on the anode side to the thermal power generation facility, it is also possible to improve the power generation efficiency of thermal power generation.

[0077] When performing oxygen reduction on the cathode side of the electrolysis device, various electrodes are used, but it is preferable to use a gas diffusion electrode with a high surface area.

[0078] <Operation of the carbon dioxide gas neutralization treatment system of this embodiment> "DAC and fan" In the method for installing a carbon dioxide gas neutralization treatment system according to this embodiment, regarding the location, it is a feature of this technology that being close to a city such as a power consumption area is not a very high priority. The carbon dioxide emission source may be not only a thermal power plant but also combined with Direct air capture (DAC) using air. Even considering the power consumption of the DAC fan, it is within the error range. When omitting the purification process, it is desirable to introduce the gas into the basic aqueous solution at the subsequent stage of the electrolyzer. When reducing oxygen in the air on the cathode side, it can be shared with the fan that sends in the air.

[0079] In a normal DACCS, it is operated with a large fan device and a large amount of power according to the processing speed of a special carbon dioxide recovery device, but the cost is extremely high. In combination with this patent, by effectively utilizing natural convection, the fan device and power cost can be suppressed.

[0080] "Carbon dioxide source" The carbon dioxide source absorbed in the present invention can be any emission source other than thermal power generation and DAC. It may be used near a large number of high-concentration emission sources such as steel mills and cement industries.

[0081] "Electric power after carbon dioxide absorption" The electric power after carbon dioxide absorption in the present invention can be used for various purposes in addition to DAC. Among them, a utilization method that can contribute to the popularization of renewable energy power is desirable. For example, it can be used for a photocatalyst - electrolysis hybrid system or an external bias for a photoelectrode reaction.

[0082] "Location" Even in the case of 100% thermal power generation, if the negative emissions of carbon dioxide can be substantially achieved by satisfying formulas (1) to (4), and gradually introducing the power of renewable energy as a power source, a truly zero-emission society can be constructed finally.

[0083] The power ratio of thermal power generation of the power source may be 100%, but it is preferably 90% or less, more preferably 80% or less. In the case of using hybrid power of solar power generation in the San Belt region, it can be 80% or less, and in promising wind power regions such as Patagonia, it may be possible to be 60% or less.

[0084] The thermal power plant may be adjacent to or away from the electrolysis system of the present invention. Preferably, it is adjacent and it is desirable to neutralize the high-concentration carbon dioxide gas discharged therefrom in the present invention.

[0085] Considering the use of basic minerals, it is desirable that the location of the neutralization system of the present invention be close to the production area of basic minerals. This is because basic minerals are heavy and it is not preferable to consume a large amount of energy for this transportation. Examples of basic minerals include kanran rock and basalt. It is important to reduce the energy for transporting heavy ores. It is preferable to locate together with a power plant (thermal + renewable energy) near the mineral production area. It is also important that seawater and salt water are as close as possible. Basic minerals are often exposed in areas close to the sea.

[0086] "Operating rate" The operating rate of the entire system such as the electrolysis device is desirably high. It is 20% or more with only renewable energy, 50% or more with hybrid power including thermal power, preferably 80% or more, and more preferably 90% or more.

[0087] "Regarding the electrolysis voltage" The actual electrolysis voltage depends on the conditions in formulas (1) to (4), but is preferably 3V or less, more preferably 2V or less, and even more preferably 1V or less. If the various methods described in the above embodiments are incorporated, the electrolysis voltage can be sufficiently reduced. The assumed pairs of oxidation reaction / reduction reaction, and their respective theoretical electrolysis voltages and actual commercial voltages are described. Cl 2 Generation / H 2 Generation: 1.3 + 0.83 = 2.13V (theoretical). Commercial 3.2V. Cl 2 Generation / O 2Reduction: 0.07 + 0.83 = 0.9 V (theoretical). Commercial use: 2.0 V. O 2 Generation / O 2 Reduction: 0.83 V (theoretical). O 2 Generation / O 2 Reduction (neutral with carbon dioxide): 0.42 V (theoretical). Fe 2+ Oxidation / O 2 Reduction (neutral with carbon dioxide): -0.04 (theoretical).

[0088] The theoretical value and the actual voltage difference in commercial use are about 1 V, which is the loss due to overvoltage. If there is a similar overvoltage in other reactions, an electrolysis voltage of about 1 to 1.8 V is assumed to be possible.

[0089] Initially, it is centered on the application of the commercial 3.2 V for the generation of Cl with a proven track record in the chloralkali process, and the commercial 2.0 V for the reduction of Cl and O, but it is considered that it will gradually be replaced in the direction of lower voltage. 2 Generation / H 2 The commercial 3.2 V for the generation of Cl and the commercial 2.0 V for the reduction of Cl and O 2 Generation / O 2 Although it is centered on the application of the commercial 3.2 V for the generation of Cl and the commercial 2.0 V for the reduction of Cl and O, it is considered that it will gradually be replaced in the direction of lower voltage.

[0090] "Regarding current" For an electrolysis voltage within the range where negative emission occurs, the higher the current and the apparent current density, the better the economy, so it is desirable. In ordinary alkaline electrolysis, the apparent current density is several hundred mA to several A / cm 2 Therefore, a level equivalent to or higher than that is desirable. Since the apparent current density increases as the actual electrode area increases, increasing the actual electrode area is very effective.

[0091] (Method for neutralizing carbon dioxide gas) The method for neutralizing carbon dioxide gas according to an embodiment of the present invention includes an electrolysis step, a carbon dioxide treatment step, an acidic liquid neutralization step, and a discharge step. In the electrolysis step, an electrolysis device having an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm is used, and the electrolytic solution is an aqueous solution containing sodium chloride. In the electrolysis step, the electrolytic solution is electrolyzed to generate a basic first aqueous solution on the cathode side of the electrolysis apparatus, and an acidic second aqueous solution is generated on the anode side of the electrolysis apparatus. In the carbon dioxide treatment step, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions. In the acidic solution neutralization step, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution. The discharge step includes a first discharge sub-step and a second discharge sub-step. In the first discharge sub-step, the first aqueous solution or the third aqueous solution is discharged to the external environment, and in the second discharge sub-step, the second aqueous solution or the fourth aqueous solution is discharged to the external environment. When the carbon dioxide gas neutralization treatment method of the present embodiment is used, the energy unit of carbon dioxide absorption is greater than at least the energy unit of carbon dioxide emissions from the power generation facility using the power consumed in the electrolysis step. Preferred embodiments of the carbon dioxide gas neutralization treatment method of the present embodiment can incorporate the preferred embodiments of the carbon dioxide gas neutralization treatment system of the present embodiment described above.

Example

[0092] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited by these examples in any way.

[0093] (Evaluation method) 「Method for measuring voltage and current」 An H-type electrolytic cell made of Pyrex, consisting of an anode cell, an intermediate cell, and a cathode cell, was used for evaluation under the condition that gas was bubbled into the anode cell and the cathode cell at a flow rate of 100 cc per minute for 1 minute as needed. The electrolytes in the cathode cell and the cathode cell were each stirred at about 100 rpm using a stirrer. In the experiment using one diaphragm, nothing was sandwiched between the anode chamber and the intermediate cell, and the evaluation was performed in two chambers of anode + intermediate cell (electrolyte: 50 mL) and cathode cell (electrolyte: 40 mL). When two diaphragms were used, the evaluation was performed in three chambers of anode cell (40 mL), intermediate cell (10 mL), and cathode cell (40 mL). When three diaphragms were used, another intermediate cell was connected, and the evaluation was performed in four chambers of anode cell (40 mL), intermediate cell (10 mL), intermediate cell’ (10 mL), and cathode cell (40 mL). As the cation exchange membrane, Nafion (NRE212) with a membrane thickness of about 51 μm was used, and as the anion exchange membrane, Selemion (ASV) with a membrane thickness of 120 μm was used. The cation exchange membrane and the anion exchange membrane were immersed in an aqueous solution adjusted to 5M NaCl manufactured by Fujifilm Wako Pure Chemical Corporation for about one day and then used in the experiment. An aqueous solution prepared in the same manner was also used for the electrolyte. As needed, H 2 SO 4 (manufactured by Fujifilm Wako Pure Chemical Corporation) and FeSO 4 (Kanto Chemical) were used to adjust the electrolyte. Pt mesh electrodes were used for the anode electrode and the cathode electrode, respectively. Using a potentiostat (manufactured by BAS), a voltage was applied under the condition of 1V to 6V, and each was energized for 40C.

[0094] "Evaluation Method for Energy Unit of Carbon Dioxide Absorption" From the above formula (1) and the foregoing description regarding formula (1), using the current efficiency Q generated by the basic aqueous solution of the electrolysis of each example and the electrolysis voltage X [V], the energy unit of carbon dioxide absorption of each example [kg-CO 2 / kWh] was obtained.

[0095] Energy unit of carbon dioxide absorption = 1.64 × Q / X (5)

[0096] "Measurement Method of pH" The pH of the electrolyte was measured using a portable pH meter (manufactured by Toa DKK. IM-32P). After measurement, 10 mL of the electrolyte was aliquoted into a cylindrical glass cell (2 cm in diameter) for measurement. After energization at 40°C, 5 mL each of the electrolyte in the anode cell was aliquoted into three 13 mL vials, vial 1 to vial 3. 0.1 g of MgO (manufactured by Fujifilm Wako Pure Chemical Corporation) or 0.1 g of FeO (manufactured by High Purity Chemical) was added to vial 1 and vial 2 respectively. After capping, it was vigorously mixed for about 10 seconds and left to stand for 15 minutes, and then the pH was measured.

[0097] "Concentration evaluation of chlorine by DPD method" After energization at 40°C, 5 mL each of the electrolyte in the anode cell was aliquoted into three 13 mL vials, vial 1 to vial 3. 0.1 g of MgO (manufactured by Fujifilm Wako Pure Chemical Corporation) or 0.1 g of FeO was added to vial 1 and vial 2 respectively. After capping, it was vigorously mixed for about 10 seconds and left to stand for 15 minutes. Then, the chlorine concentration C (unit: M) in the solution obtained by filtering the remaining undissolved FeO or MgO was calculated by the DPD method using a spectrophotometer (JASCO, V760). A DPD reagent manufactured by Shibata Chemical was used. The following formula (6) was used for the calculation of the chlorine concentration C.

[0098] C (chlorine concentration) = absorbance at 552 nm / (2.1×10 4 ) (6)

[0099] (Raw materials and equipment used) "Electrolyzer": An electrolytic cell equipped with a cylindrical platinum mesh electrode (1.5 cm in diameter, 4 cm in height) at both electrodes, which was a H-type electrolytic cell (2 cm in diameter, cylindrical) manufactured by Makuhari Rika Glass Works, with one or two intermediate tanks (2 cm in diameter, 3 cm in width) connected. O-rings made by Bitton were used for each connection. An inner diameter 1 mm Teflon (registered trademark) tube was introduced into the aqueous solution in the cathode electrolytic cell, and N 2 , CO 2 , or O 2 gas was bubbled for evaluation. Diaphragm setting method: 1 sheet, 2 sheets, 3 sheets

[0100] "Power supply": BASF Corporation "Cation exchange membrane": Nafion (NRE212) manufactured by Sigma-Aldrich, film thickness 51 μm "Anion exchange membrane": Selemion (AMV) manufactured by AGC Engineering Co., Ltd., film thickness 120 μm "Sodium chloride", "MgO powder", "Sulfuric acid": Manufactured by FUJIFILM Wako Pure Chemical Corporation "Carbon dioxide gas": Hama Shokai, normal pressure "FeO powder": High-purity chemicals

[0101] (Example 1) Electrolysis was carried out using an electrolyzer having an anode electrode, a cathode electrode, an electrolyte, and an ion exchange membrane (Nafion, a cation exchange membrane) as a diaphragm in a two-compartment cell. The solution volume of the electrolyte was 40 mL, and 5M-sodium chloride was used on both the anode side and the cathode side. N 2 The dissolved oxygen on the cathode side was purged with N gas. Pt electrodes were used for both electrodes. A current of 40 C was passed at 3 V. The electrolysis time was 17 minutes, and the temperature was 20°C to 25°C. It can be said that the operating rate of the electrolysis cell during the experiment time was 100%. The current value was 42 mA.

[0102] After electrolysis, a part of the electrolyte on both sides was transferred to another container (simulating a storage compartment). The pH on the anode side was about 12, and the pH on the cathode side was about 3. The results are shown in Table 1. The current efficiency of NaOH production was better than that of a porous membrane diaphragm and was almost 100% (in the following examples, the same ion exchange membrane (Nafion) is used, so it is assumed that the electrolysis efficiency is the same).

[0103] Also, when carbon dioxide was introduced into the basic aqueous solution (the first aqueous solution of this embodiment) of the cathode that was partially transferred, the pH became 6, indicating that it was neutralized. When FeO powder was introduced into the acidic solution (the second aqueous solution of this embodiment) of the anode that was partially transferred, simulating a basic mineral, it was found that FeO dissolved. Furthermore, when MgO powder was introduced into the acidic solution of the anode that was partially transferred, simulating a basic mineral, the pH became 10, indicating that it was neutralized.

[0104] On the anode side, 5M-sodium chloride was in contact with the Pt anode electrode, and chlorine was generated, but a part of it was dissolved in water (dissolved as hypochlorous acid). The presence of the dissolved matter of this chlorine compound could be confirmed by the DPD method (diethyl paraphenylenediamine method) (1.8 mM). Regarding the anode solution containing the chlorine compound, a part of it was transferred, and when FeO (Fe 2+ ions) was added, it decreased significantly to about 0.1 mM. Most of the chlorine compounds were reduced to HCl.

[0105] The energy unit of carbon dioxide absorption obtained using the above evaluation method was 0.55 kg-CO 2 / kWh. The results are shown in Table 1. Since the energy unit of carbon dioxide emissions of the average grid power of Tokyo Electric Power (0.44 kg-CO 2 / kWh) is larger, even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 1.8 kWh / kg-CO 2 , which has become sufficiently small.

[0106] (Example 2) Electrolysis was carried out using an electrolyzer similar to that in Example 1, except that O 2 was introduced on the cathode side. Due to the introduction of O 2 , the required voltage was reduced, and a current of about 27 mA was observed even at only 2V. Electrolysis was carried out for 40 C. It can be said that the operating rate of the electrolysis cell during the experiment time was 100%.

[0107] After electrolysis, a part of the electrolytes on both sides was transferred to another container. The pH on the anode side was about 12, and the pH on the cathode side was about 3. The current efficiency of NaOH production was almost 100%. On the anode side, 5M-sodium chloride was in contact with the Pt anode electrode, and the chlorine generation was the same as in Example 1.

[0108] In the same manner as in Example 1, the energy unit of carbon dioxide absorption was obtained. 0.82 kg-CO 2 / kWh. The results are shown in Table 1.

[0109] Since it is larger than the energy unit of carbon dioxide emissions of the average grid power of Tokyo Electric Power (0.44 kg-CO 2 / kWh), even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 1.2 kWh / kg-CO 2 and has become sufficiently small.

[0110] (Example 3) Electrolysis was carried out using the same electrolyzer as in Example 1 except that carbon dioxide was introduced on the cathode side. Due to the introduction of carbon dioxide, the required voltage was reduced, and a current of about 27 mA was observed even at only 2.6 V. Electrolysis was carried out for 40 C. It can be said that the operating rate of the electrolysis cell during the experiment time was 100%.

[0111] After electrolysis, a part of the electrolytes on both sides was transferred to another container. The pH on the anode side was immediately neutralized by carbon dioxide to about 6, and the pH on the cathode side became about 3. The results are shown in Table 1.

[0112] In the same manner as in Example 1, the energy unit of carbon dioxide absorption was obtained. 0.63 kg-CO 2 / kWh. The results are shown in Table 1.

[0113] Since it is larger than the energy unit of carbon dioxide emissions of the average grid power of Tokyo Electric Power (0.44 kg-CO 2 / kWh), even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 1.6 kWh / kg-CO 2 and has become sufficiently small.

[0114] (Example 4) Electrolysis was carried out using the same electrolyzer as in Example 1, except that both carbon dioxide and O 2 were introduced on the cathode side. Since both carbon dioxide and O 2 were introduced, the required voltage was reduced, and a current of about 17 mA was observed even at 1.6 V. Electrolysis was carried out for 40 C. The operating rate of the electrolytic cell during the experiment can be said to be 100%.

[0115] After electrolysis, a part of the electrolytes on both sides was transferred to another container. The pH on the anode side was immediately neutralized by carbon dioxide to about 9, and the pH on the cathode side was about 3. The results are shown in Table 1.

[0116] In the same manner as in Example 1, the energy consumption per unit of carbon dioxide absorption was obtained. It was 1.03 kg-CO 2 / kWh. The results are shown in Table 1.

[0117] Since it is larger than the energy consumption per unit of carbon dioxide emission of the average grid power of Tokyo Electric Power (0.44 kg-CO 2 / kWh), even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 0.97 kWh / kg-CO 2 , which has become sufficiently small.

[0118] (Example 5) As shown in Table 1, another ion exchange membrane (Nafion, a cation exchange membrane) was placed on the anode electrolyte side; electrolysis was carried out using the same electrolyzer as in Example 4, except that three types of electrolytes were in series, starting with the anode electrolyte (1 M-H 2 SO 4 ), a cation exchange membrane, a central electrolyte (5 M-sodium chloride), a cation exchange membrane, and a cathode electrolyte (5 M-sodium chloride). Due to the additional cation exchange membrane, Cl - does not come into direct contact with the anode electrode, and Cl 2The generation of hypochlorous acid is suppressed. HCl has the advantage of being generated in the central electrolyte.

[0119] Since both carbon dioxide and O 2 were introduced on the cathode side, the required voltage was reduced, and a current of about 10 mA was observed even at only 1.7 V. Electrolysis was carried out for 40 C. It can be said that the operating rate of the electrolytic cell during the experimental time was 100%.

[0120] After electrolysis, a part of the electrolytes on both sides was transferred to another container. The pH of the anode side was immediately neutralized by carbon dioxide to about 6, and the pH of the central electrolyte became about 0. The results are shown in Table 1.

[0121] In the same manner as in Example 1, the energy absorption unit of carbon dioxide was obtained. It was 0.97 kg-CO 2 / kWh. The results are shown in Table 1.

[0122] Since it is larger than the energy unit of carbon dioxide emissions of the average grid power of Tokyo Electric Power (0.44 kg-CO 2 / kWh), even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 1.03 kWh / kg-CO 2 and has become sufficiently small.

[0123] (Example 6) As shown in Table 1, an electrolyzer similar to that in Example 5 was used for electrolysis, except that the composition of the anode electrolyte (1 M-H 2 SO 4 and 0.1 M-FeSO 4 this mixture), cation exchange membrane, central electrolyte (5 M-sodium chloride), cation exchange membrane, and cathode electrolyte (5 M-sodium chloride) was used. Due to the additional cation exchange membrane, Cl - does not come into direct contact with the anode electrode, not only suppressing the generation of Cl 2 and hypochlorous acid, but also Fe 2+The presence can reduce the voltage. HCl has the advantage of being generated in the central electrolyte.

[0124] Both carbon dioxide and O are introduced to the cathode side, and further Fe is introduced to the anode side. 2 As a result, the required voltage was greatly reduced, and a current of about 19 mA was observed even at 1 V. Electrolysis was carried out for 40 C. It can be said that the operating rate of the electrolytic cell during the experimental time was 100%. 2+ After electrolysis, a part of the electrolytes on both sides was transferred to another container. The pH of the anode side was immediately neutralized by carbon dioxide to about 6, and the pH of the central electrolyte became about 0. The results are shown in Table 1.

[0125] The carbon dioxide absorption per unit was obtained in the same manner as in Example 1. It was 1.64 kg-CO

[0126] / kWh. The results are shown in Table 1. 2 Since it is larger than the carbon dioxide emission per unit of the average grid power of Tokyo Electric Power (0.44 kg-CO

[0127] / kWh), even when using this grid power (which is a mixed power), negative emissions are achieved. When comparing using the carbon dioxide energy efficiency (CEE) [kWh / kg-CO 2 , it is 0.61 kWh / kg-CO 2 and has become sufficiently small. 2

[0128] (Example 7) As shown in Table 1, an anion exchange membrane was installed between two cation exchange membranes; electrolysis was carried out using the same electrolytic cell as in Example 6 except for using an anode electrolyte (1 M-H 2 SO 4 and 0.1 M-FeSO 4 this mixture), a cation exchange membrane, a central electrolyte (5 M-sodium chloride), an anion exchange membrane, a central electrolyte '(5 M-sodium chloride), a cation exchange membrane, and a cathode electrolyte (5 M-sodium chloride). The added anion exchange membrane has the advantage of suppressing the movement of undesirable cations such as iron ions, alkali metals, and protons.

[0129] Carbon dioxide and O on the cathode side 2 In addition, Fe was introduced on the anode side. 2+ The introduction of the ion exchanger greatly reduced the required voltage, and a current of about 15 mA was observed even at only 1.2 V. Although the amount of membrane and electrolyte was increased, the decrease in the current-voltage characteristics was not so noticeable. A current of 40 C was applied.

[0130] After electrolysis, a portion of the electrolyte on both sides was transferred to a separate container. The pH of the electrolyte on the anode side was immediately neutralized by carbon dioxide to about 6, while the pH of the electrolyte in the center was about 0. The results are shown in Table 1.

[0131] The operating rate of the electrolysis cell during the experiment was 100%. The energy consumption rate of carbon dioxide absorption was obtained in the same manner as in Example 1. 2 The results are shown in Table 1.

[0132] The carbon dioxide emissions per unit of energy for Tokyo Electric Power Company's average grid power (0.44 kg-CO 2 / kWh), so even using this grid power (which is mixed) results in negative emissions. Carbon Dioxide Energy Efficiency (CEE) [kWh / kg-CO 2 ], the figure is 0.73 kWh / kg-CO 2 and became small enough.

[0133] [Table 1]

[0134] (Consideration) So far, the problem of global warming caused by carbon dioxide has been considered to be inseparable from the energy problem. However, considering the concept of neutralization reaction using the vast amount of basic minerals existing on the earth, the two problems can be separated, and a completely new solution can be provided for the former. Since carbon dioxide is a gas, it is difficult to store it on the ground. Considering the global transfer of carbon dioxide, carbon dioxide with weak acid properties can be neutralized with basic minerals in units of hundreds of millions of years, but the Paris Agreement's 2050 goal cannot be achieved on that time scale. Some concepts of the present invention are similar to Non-Patent Document 1. The electrolytic neutralization of carbon dioxide is a more direct solution than electrolytic hydrogen production, and the required number of electrons can be significantly reduced (about 1 / 4 to 1 / 8), but such a comparative advantage has not been disclosed so far. This is because the overall concept can only be achieved through the integration of fields that are too far apart, so the importance has not been recognized or discussed. The present invention is a concept of accelerating the mineral absorption rate of carbon dioxide on a global scale even when using fossil resources, and can bypass the discussions of energy laws and thermodynamics laws. Based on the inventor's cost estimate and LCA estimate, the novelty of the present invention is that negative emission conditions that can be immediately put into practical use have been found even when only thermal power generation is used for electrolysis power and continuous operation is carried out.

Industrial Applicability

[0135] The present invention provides a carbon dioxide gas neutralization treatment system and a carbon dioxide gas neutralization treatment method that can directly reduce carbon dioxide on a large scale and economically. By implementing a certain method shown in the present invention under certain conditions, it can contribute to negative emissions. It is a technology that suppresses global warming caused by carbon dioxide and promotes the realization of a low-carbon society.

Explanation of Signs

[0136] 1: Carbon dioxide gas neutralization treatment system

Claims

1. A carbon dioxide gas neutralization treatment system including an electrolysis device, a carbon dioxide treatment device, an acidic liquid neutralization device, a discharge device, and an oxygen reduction device, wherein the electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, the electrolytic solution is an aqueous solution containing sodium chloride, in the electrolysis device, the electrolytic solution is electrolyzed to generate a basic first aqueous solution on the cathode side of the electrolysis device and an acidic second aqueous solution on the anode side of the electrolysis device, in the carbon dioxide treatment device, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions, in the acidic liquid neutralization device, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution, the discharge device has a first discharge part and a second discharge part, the first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment, the second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment, the energy unit of carbon dioxide absorption is greater than at least the energy unit of carbon dioxide emissions of the power generation facility using the power consumed by the electrolysis device, A carbon dioxide gas neutralization treatment system, characterized in that on the cathode side of the electrolysis device, a gas containing oxygen is supplied using the oxygen reduction device to perform oxygen reduction.

2. The carbon dioxide gas neutralization treatment system according to claim 1, characterized in that in the electrolysis device, carbon dioxide supplied from the carbon dioxide treatment device is brought into contact with the aqueous solution on the cathode side to generate bicarbonate ions.

3. Further including a sensor, The carbon dioxide gas neutralization treatment system according to claim 1 or 2, wherein the sensor has a first sensor for monitoring pH or a second sensor for monitoring the composition of the dissolved matter in order to neutralize the second aqueous solution.

4. A carbon dioxide gas neutralization treatment system including an electrolysis device, a carbon dioxide treatment device, an acidic liquid neutralization device, and a discharge device, wherein the electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, the electrolytic solution is an aqueous solution containing sodium chloride, in the electrolysis device, the electrolytic solution is electrolyzed to generate a basic first aqueous solution on the cathode side of the electrolysis device and an acidic second aqueous solution on the anode side of the electrolysis device, In the carbon dioxide treatment device, the first aqueous solution generated on the cathode side and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate a third aqueous solution containing carbonate anions. In the acidic liquid neutralization device, the second aqueous solution generated on the anode side is neutralized with a basic substance to generate a fourth aqueous solution. The discharge device has a first discharge part and a second discharge part. The first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment. The second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment. The energy unit of carbon dioxide absorption is greater than at least the energy unit of carbon dioxide emissions from the power generation facility that supplies the power used in the electrolysis device. The acidic liquid neutralization device includes a storage section for the acidic liquid neutralization device. The second aqueous solution generated on the anode side is transferred to the storage section for the acidic liquid neutralization device. In the storage section for the acidic liquid neutralization device, the second aqueous solution is neutralized with the basic substance, and the neutralized aqueous solution is discharged to the external environment. The storage section for the acidic liquid neutralization device has two or more storage sub-sections. The two or more storage sub-sections are connected in two or more multi-stages in the order of acid concentration, and for the two or more storage sub-sections, devices for adding a basic substance are connected in two or more multi-stages. A carbon dioxide gas neutralization treatment system characterized by this.

5. The electrolysis device has two or more diaphragms. The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 4, wherein at least one of the diaphragms is disposed on the surface of the anode electrode or in the vicinity of the anode electrode.

6. The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 3, characterized in that high-purity oxygen generated on the anode side is sent to the cathode side using the oxygen reduction device.

7. The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 6, characterized in that high-purity oxygen generated on the anode side is sent to a thermal power generation facility.

8. A carbon dioxide gas neutralization treatment system including an electrolysis device, a carbon dioxide treatment device, an acidic liquid neutralization device, and a discharge device, The electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm. The electrolytic solution is an aqueous solution containing sodium chloride. Electrolyze the electrolytic solution in the electrolysis device, generate a basic first aqueous solution on the cathode side of the electrolysis device, and generate an acidic second aqueous solution on the anode side of the electrolysis device. In the carbon dioxide treatment device, cause a neutralization dissolution reaction between the first aqueous solution generated on the cathode side and carbon dioxide gas to generate a third aqueous solution containing carbonate anions. In the acidic solution neutralization device, neutralize the second aqueous solution generated on the anode side with a basic substance to generate a fourth aqueous solution. The discharge device has a first discharge part and a second discharge part. The first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment. The second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment. The energy unit of carbon dioxide absorption is greater than at least the energy unit of carbon dioxide emissions from the power generation facility using the power in the electrolysis device. The acidic solution neutralization device includes a storage section for the acidic solution neutralization device. Transfer the second aqueous solution generated on the anode side to the storage section for the acidic solution neutralization device. In the storage section for the acidic solution neutralization device, neutralize the second aqueous solution with the basic substance, and discharge the neutralized aqueous solution to the external environment. In the acidic solution neutralization device, the basic substance for neutralizing the second aqueous solution includes a basic mineral or a basic waste. wherein the basic mineral or basic waste contains at least one selected from the group consisting of Fe ２＋ , V ４＋ , and Mn ２＋ and Dissolve the basic mineral or basic waste with the second aqueous solution in the storage section for the acidic liquid neutralization device, and contact the oxidized compound of Cl － contained in the compound with its dissolved aqueous solution, and reduce Cl ２ contained in the compound with at least one selected from the group consisting of Fe ２＋ , V ４＋ , and Mn ２＋ to convert it to HCl, and a carbon dioxide gas neutralization treatment system characterized by this.

9. A carbon dioxide gas neutralization treatment system including an electrolysis device, a carbon dioxide treatment device, an acidic solution neutralization device, and a discharge device, wherein the electrolysis device has an electrolytic solution, a cathode electrode, an anode electrode, and a diaphragm, the electrolytic solution is an aqueous solution containing sodium chloride, electrolyze the electrolytic solution in the electrolysis device, generate a basic first aqueous solution on the cathode side of the electrolysis device, and generate an acidic second aqueous solution on the anode side of the electrolysis device, in the carbon dioxide treatment device, cause a neutralization dissolution reaction between the first aqueous solution generated on the cathode side and carbon dioxide gas to generate a third aqueous solution containing carbonate anions, in the acidic solution neutralization device, neutralize the second aqueous solution generated on the anode side with a basic substance to generate a fourth aqueous solution, the discharge device has a first discharge part and a second discharge part, the first discharge part discharges the first aqueous solution or the third aqueous solution to the external environment, the second discharge part discharges the second aqueous solution or the fourth aqueous solution to the external environment. The energy unit of carbon dioxide absorption is greater than at least the energy unit of carbon dioxide emissions from the power generation facility that supplies the power used in the electrolysis device. The acidic liquid neutralization device includes a storage section for the acidic liquid neutralization device. The second aqueous solution generated on the anode side is transferred to the storage section for the acidic liquid neutralization device. In the storage section for the acidic liquid neutralization device, the second aqueous solution is neutralized with the basic substance, and the neutralized aqueous solution is discharged to the external environment. In the acidic liquid neutralization device, the basic substance for neutralizing the second aqueous solution includes a basic mineral or a basic waste. The basic mineral or basic waste is a reducing agent-containing substance. The reducing agent-containing substance is a substance including a reducing agent-containing mineral, a steel slag other than the reducing agent-containing mineral, or a cement waste material other than the reducing agent-containing mineral. Dissolve the reductant-containing substance in the second aqueous solution in the storage section for the acidic liquid neutralization device, remove the substance that deteriorates the electrolytic reaction, and then Fe ２＋ , V ４＋ , Mn ２＋ A carbon dioxide gas neutralization treatment system, characterized in that a solution containing at least one kind of reductant ion selected from the group consisting of is introduced to the anode side of an electrolysis device to lower the electrolytic voltage.

10. The energy unit of the carbon dioxide absorption is 0.5 kg-CO ２ / kWh or more, and the carbon dioxide gas neutralization treatment system according to any one of claims 1 to 9.

11. In the acidic liquid neutralization device, the basic substance for neutralizing the second aqueous solution includes a basic mineral or a basic waste, and the carbon dioxide gas neutralization treatment system according to any one of claims 1 to 7.

12. In the carbon dioxide treatment device. On the cathode side, the first aqueous solution and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution is discharged to the external environment, or The carbon dioxide treatment device includes a storage section for the carbon dioxide treatment device, the first aqueous solution is transferred from the cathode side to the storage section for the carbon dioxide treatment device, and in the storage section for the carbon dioxide treatment device, the first aqueous solution and carbon dioxide gas are subjected to a neutralization dissolution reaction to generate the third aqueous solution, and the third aqueous solution is discharged to the external environment, and the carbon dioxide gas neutralization treatment system according to any one of claims 1 to 11.

13. The electrolysis device uses the power including thermal power generation. The electrolysis device is continuously operated to neutralize carbon dioxide, and the carbon dioxide gas neutralization treatment system according to any one of claims 1 to 12.

14. In the electrolysis device, the operating rate of electrolysis is 20% or more, and the carbon dioxide gas neutralization treatment system according to any one of claims 1 to 13.

15. The acidic liquid neutralization device includes a storage section for the acidic liquid neutralization device. The second aqueous solution generated on the anode side is transferred to the storage section for the acidic liquid neutralization device. In the storage section for the acidic liquid neutralization device, the second aqueous solution is neutralized with the basic substance, and the neutralized aqueous solution is discharged to the external environment. The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 3 and 6.

16. When the electrolysis voltage is X, the current efficiency is Q, and the energy unit of carbon dioxide emissions from the power generation facility is A, the relationship between the electrolysis voltage and the energy unit of carbon dioxide emissions is represented by the following formula (1). The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 15. 1.64 × Q / X > A (1) (where the unit of X is V and the unit of A is kg-CO ２ / kWh.)

17. When the electrolysis voltage is X, the energy efficiency of carbon dioxide emissions due to auxiliary equipment other than electrolysis and neutralization introduction of basic substances is Z, the overall carbon dioxide energy efficiency of the system is CEE, and the energy unit of carbon dioxide emissions from the power generation facility for the power used in electrolysis is A, the relationship is represented by the following formula (4). The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 16. CEE = (X / 1.64 × Q) + Z < (1 / A) (4) (wherein the unit of X is V, and the units of Z and A are kg-CO ２ / kWh.)

18. The carbon dioxide gas neutralization treatment system according to any one of claims 1 to 17, wherein the diaphragm is an ion exchange membrane.

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