WO2023085042A1 - Method for recovering carbon dioxide from carbon dioxide-containing gas and aqueous amine solution for recovering carbon dioxide - Google Patents

Method for recovering carbon dioxide from carbon dioxide-containing gas and aqueous amine solution for recovering carbon dioxide Download PDF

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WO2023085042A1
WO2023085042A1 PCT/JP2022/039235 JP2022039235W WO2023085042A1 WO 2023085042 A1 WO2023085042 A1 WO 2023085042A1 JP 2022039235 W JP2022039235 W JP 2022039235W WO 2023085042 A1 WO2023085042 A1 WO 2023085042A1
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carbon dioxide
amine
aqueous
solution
amine solution
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フィロツ アラム チョウドリ
朋大 木下
利紀 村岡
克則 余語
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公益財団法人地球環境産業技術研究機構
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/62—Carbon oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C215/00—Compounds containing amino and hydroxy groups bound to the same carbon skeleton
    • C07C215/02—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton
    • C07C215/04—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated
    • C07C215/06—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated and acyclic
    • C07C215/08—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated and acyclic with only one hydroxy group and one amino group bound to the carbon skeleton
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C215/00—Compounds containing amino and hydroxy groups bound to the same carbon skeleton
    • C07C215/02—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton
    • C07C215/04—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated
    • C07C215/06—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated and acyclic
    • C07C215/14—Compounds containing amino and hydroxy groups bound to the same carbon skeleton having hydroxy groups and amino groups bound to acyclic carbon atoms of the same carbon skeleton the carbon skeleton being saturated and acyclic the nitrogen atom of the amino group being further bound to hydrocarbon groups substituted by amino groups
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/40—Capture or disposal of greenhouse gases of CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Definitions

  • the present invention relates to a method for recovering carbon dioxide from a gas containing carbon dioxide, and an aqueous amine solution for recovering carbon dioxide.
  • Patent Document 1 discloses that an aqueous solution containing 2-isopropylaminoethanol and at least one selected from the group consisting of piperazines and alkanolamines is prepared by adding dioxide in the gas. It proposes a carbon dioxide recovery method including a step of absorbing carbon and a step of heating an aqueous solution in which carbon dioxide has been absorbed to desorb and recover carbon dioxide.
  • an aqueous amine solution that absorbs carbon dioxide to a high concentration as quickly as possible is required. Such requirements are higher the lower the partial pressure of carbon dioxide in the gas.
  • Several amine aqueous solutions have been proposed so far, but all of them have room for improvement in the balance between the amount of carbon dioxide absorbed and the absorption rate.
  • One aspect of the present invention is a method for recovering carbon dioxide from a gas containing carbon dioxide, comprising: a first step of absorbing carbon dioxide in an aqueous amine solution containing an amine compound; and a second step of heating to desorb and recover the carbon dioxide from the aqueous solution, wherein the amine compound is a primary amine component of the formula (I):
  • two A's each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different, and relates to a method for recovering carbon dioxide.
  • Another aspect of the invention is an aqueous amine solution for recovering carbon dioxide from a gas containing carbon dioxide, said aqueous amine solution comprising an amine compound, said amine compound comprising, as a primary amine component, :
  • two A each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different, for recovering carbon dioxide It relates to aqueous amine solutions.
  • the balance between the amount of carbon dioxide absorbed and the absorption speed can be well controlled, so carbon dioxide can be efficiently recovered at low cost.
  • the aqueous amine solution quickly absorbs a sufficient amount of carbon dioxide even if the partial pressure of carbon dioxide in the gas is less than 5 kPa.
  • FIG. 2 is a graph showing the relationship between the amount of carbon dioxide absorbed and the rate of absorption by aqueous amine solutions of Examples and Comparative Examples.
  • Embodiments of the method for recovering carbon dioxide and the aqueous amine solution for recovering carbon dioxide will be described below. is not limited to
  • any of the illustrated lower limits and any of the illustrated upper limits can be arbitrarily combined as long as the lower limit is not greater than or equal to the upper limit. .
  • a plurality of materials one of them may be selected and used alone, or two or more may be used in combination.
  • the content (% by mass) of an amine compound in an aqueous amine solution is defined as the ratio of the amine compound to the mass of the aqueous amine solution (total of water and amine compound) excluding carbon dioxide absorbed in the aqueous amine solution. means percentage.
  • a method for recovering carbon dioxide from a gas containing carbon dioxide has a first step and a second step.
  • the first step involves absorbing carbon dioxide into an aqueous amine solution containing an amine compound.
  • the second step includes heating the carbon dioxide-absorbed amine aqueous solution to desorb and recover the carbon dioxide from the aqueous solution.
  • the method of absorbing carbon dioxide in the aqueous amine solution is not particularly limited.
  • the method of contacting the gas containing carbon dioxide with the aqueous amine solution is not limited.
  • the method of heating the aqueous amine solution in which carbon dioxide has been absorbed is not limited.
  • the method of recovering the carbon dioxide desorbed from the aqueous amine solution is also not limited.
  • the amine compound in the amine aqueous solution contains a primary amine component and a secondary amine component.
  • the amine compound may contain a tertiary amine component other than the primary amine component and the secondary amine component, provided that the sum of the primary amine component and the secondary amine component is the sum of the amine compounds (total of all amine compounds). For example, it preferably accounts for 70% by mass or more, more preferably 80% by mass or more or 90% by mass or more.
  • the primary amine component has the formula (I):
  • IPAE 2-isopropylaminoethanol
  • the carbon dioxide absorption performance refers to the absorption amount (loading amount) of carbon dioxide per unit mass and the desorption property (desorption property) of carbon dioxide.
  • the desorption property (desorption property) of carbon dioxide refers to the desorption amount and the desorption rate.
  • Carbon dioxide absorbed by the aqueous amine solution forms either a carbamate anion or a bicarbonate ion in the aqueous amine solution.
  • the heat of reaction upon absorption is higher for the reaction that produces the carbamate anion.
  • Such a difference is considered to be due to the difference in molecular structure of the amine compound.
  • the difference in bonding state between carbon dioxide and the amine compound affects the difference in desorption rate and desorption amount in the carbon dioxide desorption step.
  • 2-aminoethanol which is a typical primary alkanolamine, produces a large amount of carbamate anions that exhibit high heat of reaction, and a small amount of bicarbonate ions that exhibit low heat of reaction.
  • 2-Ethylaminoethanol (EAE) which is a secondary alkanolamine, produces a large amount of carbamate anions exhibiting a high heat of reaction, and produces a small amount of bicarbonate ions exhibiting a low heat of reaction, similarly to MEA.
  • IPAE is a secondary alkanolamine
  • it produces traces of carbamate anions and mostly produces bicarbonate ions. This is presumably because the isopropyl group substituting the amino group of the IPAE molecule is bulky unlike the ethyl group of EAE, and its steric properties significantly inhibit the formation of carbamate bonds.
  • the above characteristics of IPAE are considered to be due to the absorption mechanism of carbon dioxide by the production of bicarbonate ions.
  • IPAE has a slow carbon dioxide absorption rate and, for example, when targeting a gas containing carbon dioxide at a partial pressure of less than 5 kPa, the carbon dioxide absorption performance is also insufficient.
  • IPAE has a relatively low boiling point (about 171° C.), so it is easily volatilized when heating the amine aqueous solution in the second step, and loss is likely to occur.
  • Patent Document 1 proposes to use a specific piperazine compound or a specific alkanolamine compound together with IPAE in order to supplement the absorption rate of IPAE when targeting a gas with a carbon dioxide concentration of, for example, 5 to 30% by volume. are doing.
  • a specific piperazine compound or a specific alkanolamine compound together with IPAE in order to supplement the absorption rate of IPAE when targeting a gas with a carbon dioxide concentration of, for example, 5 to 30% by volume. are doing.
  • the absorption rate is insufficient especially when the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa.
  • the piperazine compound since the piperazine compound has low solubility in water, it may precipitate in an aqueous solution.
  • the second component has the general formula (II):
  • two A's each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different.
  • the secondary amine component has a high absorption rate of carbon dioxide, and this tendency is remarkable particularly when the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less), Carbon dioxide absorption performance is also at a sufficient level.
  • the secondary amine component since the secondary amine component has a relatively high boiling point, it is difficult to volatilize when the aqueous amine solution is heated in the second step, and loss is less likely to occur.
  • the secondary amine component has a high solubility in water, and there is no fear of precipitation in an aqueous solution.
  • the secondary amine component has a smaller carbon dioxide loading amount than IPAE, but a high loading amount can be maintained by using the secondary amine component and IPAE together.
  • aqueous amine solution containing a secondary amine component and IPAE rapidly absorbs a sufficient amount of carbon dioxide even when targeting a gas containing carbon dioxide at a partial pressure of less than 5 kPa. Therefore, carbon dioxide can be efficiently recovered at low cost from a gas containing low-concentration carbon dioxide (for example, the atmosphere).
  • AEAE N-(2-aminoethyl)-2-aminoethanol
  • both A are ethylene groups having 2 carbon atoms
  • AEAE has a high boiling point (about 244° C.), is stable and hardly causes loss, and has very high solubility in water.
  • the content of AEAE in the secondary amine component is, for example, preferably 70% by mass or more, preferably 80% by mass or more, and may be 90% by mass or more (or 100%).
  • total amine amount The content of the amine compound (total of all amine compounds) contained in the amine aqueous solution (hereinafter also referred to as "total amine amount") is not particularly limited, but is, for example, 20% by mass to 60% by mass, and 30% by mass. It may be from 30 to 55% by mass, or from 40 to 55% by mass.
  • total amine content is 60% by mass or less, it is believed that the effect of water as an activator is improved, the amount of carbon dioxide absorbed is likely to increase, and the miscibility between the primary amine component and the secondary amine component is good. become. Also, the viscosity of the aqueous amine solution is kept low.
  • the carbon dioxide absorption performance per unit volume of the amine aqueous solution can be sufficiently increased, so that carbon dioxide can be recovered more efficiently. It can be carried out.
  • the content (C2) of the secondary amine component contained in the amine compound may be greater than the content (C1) of the primary amine component (IPAE) contained in the amine compound.
  • the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less)
  • the absorption rate of carbon dioxide by the amine aqueous solution increases, and carbon dioxide is more efficiently absorbed. can be recovered.
  • the ratio of the content C2 of the secondary amine component to the content C1 of the primary amine component (IPAE): C2/C1 may be, for example, 1.5 to 3, 2 to 3, or 2 to 2.5. good.
  • the content of the primary amine component (IPAE) contained in the amine aqueous solution is, for example, 5% by mass or more and less than 30% by mass, and may be 10% by mass or more and 25% by mass or less.
  • the content of the secondary amine component contained in the aqueous amine solution is, for example, 15% by mass or more and 55% by mass or less, may be 25% by mass or more and 50% by mass or less, or may be 30% by mass or more and 45% by mass. It can be below.
  • the carbon dioxide absorption performance and desorption performance of the aqueous amine solution can be further improved.
  • the C2/C1 ratio is about 0.05, the effect of improving the rate of absorption of carbon dioxide by the secondary amine component is observed.
  • C2/C1 ratios of 0.05 and above, and even 0.1 and above more stable improvements are seen.
  • the aqueous amine solution may contain various additives.
  • a phosphoric acid anticorrosive agent for preventing corrosion of equipment a silicone antifoaming agent for preventing foaming, an antioxidant for preventing deterioration of the amine compound, and the like may be added to the aqueous amine solution.
  • the aqueous amine solution is suitable for recovering carbon dioxide from gases containing carbon dioxide at low concentrations. That is, the first step may be a step of bringing a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less) into contact with the aqueous amine solution to absorb the carbon dioxide in the aqueous amine solution.
  • the gas containing carbon dioxide at a partial pressure of less than 5 kPa may be the atmosphere. That is, the present disclosure may be applied to DAC (Direct Air Capture).
  • the gas containing carbon dioxide at a partial pressure of less than 5 kPa may be a gas containing carbon dioxide that is emitted in a closed space by human breathing, energy conversion by equipment, or the like. Examples of closed spaces include indoor spaces such as submersible research vessels, space stations, buildings, and offices.
  • a gas containing carbon dioxide may contain a higher concentration of carbon dioxide.
  • Gases containing carbon dioxide are used, for example, in thermal power plants that use coal, heavy oil, natural gas, etc. as fuel, blast furnaces in steel plants that reduce iron oxide with coke, and steel plants that burn carbon in pig iron to make steel. converters, boilers in various manufacturing plants, kilns in cement plants, etc., and exhaust gases emitted from transportation equipment such as automobiles, ships, and aircraft that use gasoline, heavy oil, light oil, etc. as fuel.
  • the gas containing carbon dioxide may be brought into contact with an aqueous amine solution at a temperature of, for example, 60°C or lower (further 50°C or lower, or 45°C or lower), preferably 20°C to 45°C. may come into contact with This can promote the absorption of carbon dioxide into the aqueous amine solution.
  • Examples of the method of contacting a gas containing carbon dioxide with an aqueous amine solution include a method of bubbling a gas containing carbon dioxide into an aqueous amine solution, a method of atomizing or spraying an aqueous amine solution into a gas stream containing carbon dioxide, and a method of spraying an aqueous amine solution into a gas stream containing carbon dioxide. It can be carried out by a method of contacting a gas containing carbon dioxide and an aqueous amine solution in a countercurrent manner.
  • the pressure of the gas containing carbon dioxide may be approximately atmospheric pressure.
  • the gas may be pressurized to higher pressures to enhance absorption performance. From the viewpoint of suppressing energy consumption required for gas compression, it is preferable to perform the first step under atmospheric pressure.
  • the carbon dioxide-absorbed amine aqueous solution may be heated, for example, to a temperature of 70°C or higher.
  • the carbon dioxide-absorbed amine aqueous solution may be heated to 80°C or higher, further 90°C or higher, preferably 90 to 120°C. This can promote desorption of carbon dioxide from the aqueous amine solution.
  • the boiling point of the aqueous amine solution according to the present embodiment can be 120° C. or higher, it can be heated to 120° C. without boiling even under atmospheric pressure.
  • the carbon dioxide-absorbed amine aqueous solution is heated in the same manner as distillation and bubbled in a kettle to desorb carbon dioxide.
  • a method of heating by widening the liquid contact interface in the desorption tower containing the material may be employed. This liberates carbon dioxide from the carbamate or bicarbonate ions.
  • the pressure of the atmosphere of the aqueous amine solution when desorbing carbon dioxide may be approximately atmospheric pressure.
  • the atmosphere may be depressurized to facilitate desorption of carbon dioxide.
  • the pressure in the inner space may be higher than the atmospheric pressure.
  • the aqueous amine solution after desorbing carbon dioxide is recycled to absorb carbon dioxide again in the first step.
  • the purity of the recovered carbon dioxide can be extremely high, for example, about 95-99.9% by volume.
  • High-concentration carbon dioxide can be used as a raw material for synthesizing chemicals, polymeric substances, refrigerants for food freezing, and the like.
  • Gas is collected at the inlet and outlet of the mixed gas of the gas absorption bottle, and the carbon dioxide concentration in the gas is continuously measured with an infrared carbon dioxide meter (HORIBA GAS ANALYZER VA-3000). The amount of carbon dioxide absorbed was monitored from the difference in the carbon dioxide flow rate at the outlet.
  • HORIBA GAS ANALYZER VA-3000 The amount of carbon dioxide absorbed was monitored from the difference in the carbon dioxide flow rate at the outlet.
  • the absorption amount of carbon dioxide at the time when the carbon dioxide concentration at the outlet matches the carbon dioxide concentration at the inlet was taken as the saturated absorption amount.
  • the temperature of the amine aqueous solution A1 in which carbon dioxide had been absorbed to a saturated state was raised to 120° C. under atmospheric pressure to desorb carbon dioxide from the amine aqueous solution A1.
  • the gas absorption bottle was filled with carbon dioxide, so the partial pressure of carbon dioxide (P CO2 ) at 120° C. was approximately 100 kPa.
  • a gas chromatograph-type total organic carbon meter (SHIMADZU TOC-VCSH) was used to measure the amount of inorganic carbon in the aqueous amine solution A1 in which carbon dioxide was absorbed to a saturated state at 40°C and in the aqueous amine solution A1 after desorption of carbon dioxide at 120°C. ) to determine the absorption amount of each carbon dioxide.
  • Table 1 shows the absorption rate of carbon dioxide, the saturated absorption amount of carbon dioxide at 40 ° C. (M_rich), the absorption amount of carbon dioxide after desorbing carbon dioxide at 120 ° C. (M_lean), and these The carbon dioxide recovery amount (loading amount, M_rich ⁇ M_lean) obtained from the difference is shown.
  • the absorption amount is indicated by the mass (g-CO 2 /L-soln.) of carbon dioxide absorbed by a unit volume (1 L) of the amine aqueous solution.
  • Example 1 The same measurement as in Example 1 was performed except that 50 mL of an aqueous amine solution B1 containing 30% by mass of IPAE, 20% by mass of piperazine (PZ), and 50% by mass of water (total 100%) was filled in a gas absorption bottle. . Table 1 shows the results.
  • Example 2 The same measurement as in Example 1 was performed except that 50 mL of an amine aqueous solution C1 (100% in total) containing 30% by mass of monoethanolamine (MEA) and 70% by mass of water was filled in a gas absorption bottle. Table 1 shows the results.
  • FIG. 1 shows the relationship between the absorption amount of carbon dioxide (Absorption amount (g/L-soln.)) at 40° C. and the absorption rate (Absorption rate (g-CO 2 /L/min.)).
  • Absorption amount g/L-soln.
  • Absorption rate g-CO 2 /L/min.
  • the tact time for collecting carbon dioxide by repeating the absorption and desorption of carbon dioxide the better. Since the aqueous amine solution A1 rapidly absorbs and releases carbon dioxide in the loading area, the tact time is significantly shorter than the aqueous amine solutions B1 and C1. That is, it can be said that carbon dioxide can be efficiently recovered at low cost by using an aqueous amine solution such as the aqueous amine solution A1.
  • the method for recovering carbon dioxide according to the present disclosure it is possible to efficiently recover carbon dioxide in gas at low cost.
  • the aqueous amine solution according to the present disclosure even when the partial pressure of carbon dioxide in gas is low, carbon dioxide can be rapidly absorbed to a high concentration.
  • the present disclosure is suitable for practical use of, for example, a DAC (Direct Air Capture) that recovers carbon dioxide from the atmosphere.
  • DAC Direct Air Capture

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Abstract

Provided is a method for recovering carbon dioxide, that includes: a first step in which an aqueous amine solution that contains a amine compound is caused to absorb carbon dioxide in a gas containing carbon dioxide; and a second step in which the aqueous amine solution that has absorbed the carbon dioxide is heated and the carbon dioxide is desorbed and recovered from the aqueous solution. The amine compound includes 2-isopropyl aminoethanol and H2N-A-NH-A-OH (where the two As each indicate a C2–4 alkylene group, respectively, that may be the same or different from each other).

Description

二酸化炭素を含むガスから二酸化炭素を回収する方法、および、二酸化炭素を回収するためのアミン水溶液Method for recovering carbon dioxide from gas containing carbon dioxide and aqueous amine solution for recovering carbon dioxide
　本発明は、二酸化炭素を含むガスから二酸化炭素を回収する方法、および、二酸化炭素を回収するためのアミン水溶液に関する。 The present invention relates to a method for recovering carbon dioxide from a gas containing carbon dioxide, and an aqueous amine solution for recovering carbon dioxide.
　地球温暖化は、人間の活動が活発になることに付随して増大する二酸化炭素等の温室効果ガスが大気中に増大するためであると考えられている。地球温暖化を防止するために、二酸化炭素の削減に向けての対策が緊急に必要となっている。 Global warming is thought to be due to an increase in greenhouse gases such as carbon dioxide in the atmosphere, which accompanies increased human activity. In order to prevent global warming, there is an urgent need for measures to reduce carbon dioxide.
　ガス中の二酸化炭素を回収する方法として、例えば、特許文献１は、２－イソプロピルアミノエタノール、並びに、ピペラジン類及びアルカノールアミン類からなる群より選択される少なくとも一種を含有する水溶液にガス中の二酸化炭素を吸収させる工程、および、二酸化炭素が吸収された水溶液を加熱して、二酸化炭素を脱離して回収する工程を含む二酸化炭素の回収方法を提案している。 As a method for recovering carbon dioxide in a gas, for example, Patent Document 1 discloses that an aqueous solution containing 2-isopropylaminoethanol and at least one selected from the group consisting of piperazines and alkanolamines is prepared by adding dioxide in the gas. It proposes a carbon dioxide recovery method including a step of absorbing carbon and a step of heating an aqueous solution in which carbon dioxide has been absorbed to desorb and recover carbon dioxide.
ＷＯ２００９／００１８０４号パンフレットWO2009/001804 pamphlet
　アミン水溶液によりガス中の二酸化炭素を低コストで効率的に回収するためには、二酸化炭素をできるだけ高濃度まで速やかに吸収するアミン水溶液が求められる。そのような要求は、ガス中の二酸化炭素の分圧が小さいほど高くなる。これまでにいくつかのアミン水溶液が提案されているが、いずれも二酸化炭素の吸収量と吸収速度とのバランスにおいて改善の余地がある。 In order to efficiently recover carbon dioxide in gas at low cost with an aqueous amine solution, an aqueous amine solution that absorbs carbon dioxide to a high concentration as quickly as possible is required. Such requirements are higher the lower the partial pressure of carbon dioxide in the gas. Several amine aqueous solutions have been proposed so far, but all of them have room for improvement in the balance between the amount of carbon dioxide absorbed and the absorption rate.
　本発明の一側面は、二酸化炭素を含むガスから二酸化炭素を回収する方法であって、アミン化合物を含むアミン水溶液に二酸化炭素を吸収させる第１工程と、前記二酸化炭素を吸収させた前記アミン水溶液を加熱して前記二酸化炭素を水溶液から脱離させて回収する第２工程と、を含み、前記アミン化合物が、第１アミン成分として、式（I）： One aspect of the present invention is a method for recovering carbon dioxide from a gas containing carbon dioxide, comprising: a first step of absorbing carbon dioxide in an aqueous amine solution containing an amine compound; and a second step of heating to desorb and recover the carbon dioxide from the aqueous solution, wherein the amine compound is a primary amine component of the formula (I):
Figure JPOXMLDOC01-appb-C000005
  
Figure JPOXMLDOC01-appb-C000005
  
で表される２－イソプロピルアミノエタノールを含み、かつ第２アミン成分として、一般式（II）： and containing 2-isopropylaminoethanol represented by the general formula (II) as a secondary amine component:
Figure JPOXMLDOC01-appb-C000006
  
Figure JPOXMLDOC01-appb-C000006
  
で表されるアルカノールアミンを含み、前記一般式（II）中、２つのＡは、それぞれ炭素数２～４のアルキレン基を示し、かつ互いに同一でも異なってもよい、二酸化炭素の回収方法に関する。 In the general formula (II), two A's each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different, and relates to a method for recovering carbon dioxide.
　本発明の別の側面は、二酸化炭素を含むガスから二酸化炭素を回収するアミン水溶液であって、前記アミン水溶液は、アミン化合物を含み、前記アミン化合物が、第１アミン成分として、式（I）： Another aspect of the invention is an aqueous amine solution for recovering carbon dioxide from a gas containing carbon dioxide, said aqueous amine solution comprising an amine compound, said amine compound comprising, as a primary amine component, :
Figure JPOXMLDOC01-appb-C000007
  
Figure JPOXMLDOC01-appb-C000007
  
で表される２－イソプロピルアミノエタノールを含み、かつ第２アミン成分として、一般式（ＩＩ）： and containing 2-isopropylaminoethanol represented by and as a secondary amine component, the general formula (II):
Figure JPOXMLDOC01-appb-C000008
  
Figure JPOXMLDOC01-appb-C000008
  
で表されるアルカノールアミンを含み、前記一般式（II）中、２つのＡは、それぞれ炭素数２～４のアルキレン基を示し、かつ互いに同一でも異なってもよい、二酸化炭素を回収するためのアミン水溶液に関する。 In the general formula (II), two A each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different, for recovering carbon dioxide It relates to aqueous amine solutions.
　本開示によれば、二酸化炭素の回収方法において、二酸化炭素の吸収量と吸収速度とのバランスを良好に制御できるため、二酸化炭素を低コストで効率的に回収することができるようになる。上記アミン水溶液は、ガス中の二酸化炭素の分圧が５ｋＰａ未満であっても十分量の二酸化炭素を速やかに吸収する。 According to the present disclosure, in the carbon dioxide recovery method, the balance between the amount of carbon dioxide absorbed and the absorption speed can be well controlled, so carbon dioxide can be efficiently recovered at low cost. The aqueous amine solution quickly absorbs a sufficient amount of carbon dioxide even if the partial pressure of carbon dioxide in the gas is less than 5 kPa.
　本発明の新規な特徴を添付の請求の範囲に記述するが、本発明は、構成および内容の両方に関し、本発明の他の目的および特徴と併せ、図面を照合した以下の詳細な説明によりさらによく理解されるであろう。 While the novel features of the present invention are set forth in the appended claims, the present invention, both as to construction and content, together with other objects and features of the present invention, will be further developed by the following detailed description in conjunction with the drawings. will be well understood.
実施例および比較例のアミン水溶液による二酸化炭素の吸収量と吸収速度との関係を示す図である。FIG. 2 is a graph showing the relationship between the amount of carbon dioxide absorbed and the rate of absorption by aqueous amine solutions of Examples and Comparative Examples.
　以下、二酸化炭素の回収方法および二酸化炭素を回収するためのアミン水溶液の実施形態について説明するが、本開示に係る二酸化炭素の回収方法および二酸化炭素を回収するためのアミン水溶液は、以下の実施形態に限定されるものではない。 Embodiments of the method for recovering carbon dioxide and the aqueous amine solution for recovering carbon dioxide will be described below. is not limited to
　以下の説明では、具体的な数値、材料等を例示する場合があるが、本開示の効果が得られる限り、他の数値、材料等を適用してもよい。なお、本開示に特徴的な部分以外の構成要素には、公知の二酸化炭素の回収方法およびアミン水溶液の構成要素を適用してもよい。この明細書において、「数値Ａ～数値Ｂの範囲」という場合、当該範囲には数値Ａおよび数値Ｂが含まれる。 In the following description, specific numerical values, materials, etc. may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure can be obtained. Note that components other than the characteristic parts of the present disclosure may be applied to known carbon dioxide recovery methods and components of an aqueous amine solution. In this specification, when referring to "a range from numerical value A to numerical value B", numerical value A and numerical value B are included in the range.
　以下の説明において、特定の物性や条件などに関する数値の下限と上限とを例示した場合、下限が上限以上とならない限り、例示した下限のいずれかと例示した上限のいずれかを任意に組み合わせることができる。複数の材料が例示される場合、その中から１種を選択して単独で用いてもよく、２種以上を組み合わせて用いてもよい。 In the following description, when lower and upper limits of numerical values relating to specific physical properties, conditions, etc. are exemplified, any of the illustrated lower limits and any of the illustrated upper limits can be arbitrarily combined as long as the lower limit is not greater than or equal to the upper limit. . When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more may be used in combination.
　この明細書において、アミン水溶液中でのアミン化合物の含有率（質量％）は、アミン水溶液に吸収されている二酸化炭素を除いたアミン水溶液（水とアミン化合物との合計）の質量に対するアミン化合物の百分率を意味する。 In this specification, the content (% by mass) of an amine compound in an aqueous amine solution is defined as the ratio of the amine compound to the mass of the aqueous amine solution (total of water and amine compound) excluding carbon dioxide absorbed in the aqueous amine solution. means percentage.
　二酸化炭素を含むガスから二酸化炭素を回収する方法は、第１工程と第２工程とを有する。第１工程は、アミン化合物を含むアミン水溶液に二酸化炭素を吸収させることを含む。第２工程は、二酸化炭素を吸収させたアミン水溶液を加熱して、二酸化炭素を水溶液から脱離させて回収することを含む。第１工程において、アミン水溶液に二酸化炭素を吸収させる方法は特に限定されない。例えば、二酸化炭素を含むガスとアミン水溶液との接触方法は限定されない。第２工程において、二酸化炭素を吸収させたアミン水溶液を加熱する方法は限定されない。アミン水溶液から脱離させた二酸化炭素を回収する方法も限定されない。 A method for recovering carbon dioxide from a gas containing carbon dioxide has a first step and a second step. The first step involves absorbing carbon dioxide into an aqueous amine solution containing an amine compound. The second step includes heating the carbon dioxide-absorbed amine aqueous solution to desorb and recover the carbon dioxide from the aqueous solution. In the first step, the method of absorbing carbon dioxide in the aqueous amine solution is not particularly limited. For example, the method of contacting the gas containing carbon dioxide with the aqueous amine solution is not limited. In the second step, the method of heating the aqueous amine solution in which carbon dioxide has been absorbed is not limited. The method of recovering the carbon dioxide desorbed from the aqueous amine solution is also not limited.
　アミン水溶液中のアミン化合物は、第１アミン成分と第２アミン成分とを含む。アミン化合物は、第１アミン成分および第２アミン成分以外の第３アミン成分を含んでもよいが、第１アミン成分と第２アミン成分との合計が、アミン化合物（全てのアミン化合物の合計）の例えば７０質量％以上を占めることが望ましく、８０質量％以上もしくは９０質量％以上を占めることがより望ましい。 The amine compound in the amine aqueous solution contains a primary amine component and a secondary amine component. The amine compound may contain a tertiary amine component other than the primary amine component and the secondary amine component, provided that the sum of the primary amine component and the secondary amine component is the sum of the amine compounds (total of all amine compounds). For example, it preferably accounts for 70% by mass or more, more preferably 80% by mass or more or 90% by mass or more.
　第１アミン成分は、式（I）： The primary amine component has the formula (I):
Figure JPOXMLDOC01-appb-C000009
  
Figure JPOXMLDOC01-appb-C000009
  
で表される２－イソプロピルアミノエタノール（以下、「ＩＰＡＥ」とも称する。）である。ＩＰＡＥは、例えば、５ｋＰａ以上の分圧で二酸化炭素を含むガスを対象とする場合には、二酸化炭素の吸収性能と劣化耐性に優れ、反応熱も小さい点で優れている。ここで、二酸化炭素の吸収性能とは、単位質量あたりの二酸化炭素の吸収量（ローディング量）および二酸化炭素の放散性（脱離性）をいう。二酸化炭素の放散性（脱離性）は、脱離量および脱離速度をいう。 is 2-isopropylaminoethanol (hereinafter also referred to as “IPAE”) represented by For example, when a gas containing carbon dioxide at a partial pressure of 5 kPa or more is targeted, IPAE is excellent in that it has excellent carbon dioxide absorption performance and resistance to deterioration, and has low reaction heat. Here, the carbon dioxide absorption performance refers to the absorption amount (loading amount) of carbon dioxide per unit mass and the desorption property (desorption property) of carbon dioxide. The desorption property (desorption property) of carbon dioxide refers to the desorption amount and the desorption rate.
　アミン水溶液によって吸収された二酸化炭素は、アミン水溶液中でカルバミン酸アニオンまたは重炭酸イオンのいずれかを形成している。吸収時の反応熱は、カルバミン酸アニオンを生成する反応の方が高い。このような相違点は、アミン化合物の分子構造の差によると考えられる。二酸化炭素とアミン化合物との結合状態の差は、二酸化炭素の脱離工程における脱離速度および脱離量の差に影響する。 Carbon dioxide absorbed by the aqueous amine solution forms either a carbamate anion or a bicarbonate ion in the aqueous amine solution. The heat of reaction upon absorption is higher for the reaction that produces the carbamate anion. Such a difference is considered to be due to the difference in molecular structure of the amine compound. The difference in bonding state between carbon dioxide and the amine compound affects the difference in desorption rate and desorption amount in the carbon dioxide desorption step.
　１３Ｃ－ＮＭＲ測定によれば、代表的な一級アルカノールアミンである２－アミノエタノール（ＭＥＡ）は高い反応熱を示すカルバミン酸アニオンを多く生成し、低い反応熱を示す重炭酸イオンの生成は少ない。二級アルカノールアミンである２－エチルアミノエタノール（ＥＡＥ）は、ＭＥＡと同様に、高い反応熱を示すカルバミン酸アニオンを多く生成し、低い反応熱を示す重炭酸イオンの生成は少ない。 　According to 13C-NMR measurements, 2-aminoethanol (MEA), which is a typical primary alkanolamine, produces a large amount of carbamate anions that exhibit high heat of reaction, and a small amount of bicarbonate ions that exhibit low heat of reaction. 2-Ethylaminoethanol (EAE), which is a secondary alkanolamine, produces a large amount of carbamate anions exhibiting a high heat of reaction, and produces a small amount of bicarbonate ions exhibiting a low heat of reaction, similarly to MEA.
　これに対し、ＩＰＡＥは、二級アルカノールアミンでありながら、カルバミン酸アニオンが痕跡程度で生成し、大半は重炭酸イオンを生成する。これは、ＩＰＡＥ分子のアミノ基に置換しているイソプロピル基が、ＥＡＥのエチル基とは違って嵩高く、その立体的特性によりカルバメート結合の生成が著しく阻害されるためと推定される。ＩＰＡＥの上記特徴は、重炭酸イオンの生成による二酸化炭素の吸収機構に起因すると考えられる。 On the other hand, although IPAE is a secondary alkanolamine, it produces traces of carbamate anions and mostly produces bicarbonate ions. This is presumably because the isopropyl group substituting the amino group of the IPAE molecule is bulky unlike the ethyl group of EAE, and its steric properties significantly inhibit the formation of carbamate bonds. The above characteristics of IPAE are considered to be due to the absorption mechanism of carbon dioxide by the production of bicarbonate ions.
　一方、ＩＰＡＥは、二酸化炭素の吸収速度が遅く、かつ、例えば、５ｋＰａ未満の分圧で二酸化炭素を含むガスを対象とする場合には、二酸化炭素の吸収性能も不十分である。また、ＩＰＡＥは沸点（約１７１℃）が比較的低いため、第２工程でアミン水溶液を加熱する際に揮散しやすく、ロスが生じやすい。 On the other hand, IPAE has a slow carbon dioxide absorption rate and, for example, when targeting a gas containing carbon dioxide at a partial pressure of less than 5 kPa, the carbon dioxide absorption performance is also insufficient. In addition, IPAE has a relatively low boiling point (about 171° C.), so it is easily volatilized when heating the amine aqueous solution in the second step, and loss is likely to occur.
　特許文献１では、二酸化炭素濃度が例えば５～３０体積％のガスを対象とする場合にＩＰＡＥの吸収速度を補うために、特定のピペラジン化合物または特定のアルカノールアミン化合物をＩＰＡＥと併用することを提案している。しかし、吸収速度を速めるのには限界があり、特に５ｋＰａ未満の分圧で二酸化炭素を含むガスを対象とする場合には、吸収速度が不十分である。また、ピペラジン化合物は水に対する溶解度が低いため、水溶液中で析出する可能性がある。 Patent Document 1 proposes to use a specific piperazine compound or a specific alkanolamine compound together with IPAE in order to supplement the absorption rate of IPAE when targeting a gas with a carbon dioxide concentration of, for example, 5 to 30% by volume. are doing. However, there is a limit to increasing the absorption rate, and the absorption rate is insufficient especially when the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa. Moreover, since the piperazine compound has low solubility in water, it may precipitate in an aqueous solution.
　これに対し、第２アミン成分をＩＰＡＥと併用する場合、二酸化炭素の吸収速度が顕著に改善される。第２成分は、一般式（II）： On the other hand, when the secondary amine component is used in combination with IPAE, the absorption rate of carbon dioxide is significantly improved. The second component has the general formula (II):
Figure JPOXMLDOC01-appb-C000010
  
Figure JPOXMLDOC01-appb-C000010
  
で表されるアルカノールアミンであり、一般式（II）中、２つのＡは、それぞれ炭素数２～４のアルキレン基を示し、かつ互いに同一でも異なってもよい。 In general formula (II), two A's each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different.
　第２アミン成分は、二酸化炭素の吸収速度が速く、特に５ｋＰａ未満（更には２ｋＰａ以下、もしくは１ｋＰａ以下）の分圧で二酸化炭素を含むガスを対象とする場合に、その傾向が顕著であり、二酸化炭素の吸収性能も十分なレベルである。また、第２アミン成分は沸点が比較的高いため、第２工程でアミン水溶液を加熱する際に揮散しにくく、ロスが生じにくい。また、第２アミン成分は水に対する溶解度が高く、水溶液中で析出する懸念がない。 The secondary amine component has a high absorption rate of carbon dioxide, and this tendency is remarkable particularly when the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less), Carbon dioxide absorption performance is also at a sufficient level. In addition, since the secondary amine component has a relatively high boiling point, it is difficult to volatilize when the aqueous amine solution is heated in the second step, and loss is less likely to occur. In addition, the secondary amine component has a high solubility in water, and there is no fear of precipitation in an aqueous solution.
　なお、第２アミン成分は、二酸化炭素のローディング量がＩＰＡＥに比べると少ないが、第２アミン成分とＩＰＡＥとを併用することで高いローディング量を維持できる。第２アミン成分とＩＰＡＥとを併用することで、それぞれの長所が最大限に発揮される。第２アミン成分とＩＰＡＥとを含むアミン水溶液は、５ｋＰａ未満の分圧で二酸化炭素を含むガスを対象とする場合でも十分量の二酸化炭素を速やかに吸収する。よって、低濃度の二酸化炭素を含むガス（例えば大気）から二酸化炭素を低コストで効率的に回収することができるようになる。 The secondary amine component has a smaller carbon dioxide loading amount than IPAE, but a high loading amount can be maintained by using the secondary amine component and IPAE together. By using the secondary amine component and IPAE together, the advantages of each are maximized. An aqueous amine solution containing a secondary amine component and IPAE rapidly absorbs a sufficient amount of carbon dioxide even when targeting a gas containing carbon dioxide at a partial pressure of less than 5 kPa. Therefore, carbon dioxide can be efficiently recovered at low cost from a gas containing low-concentration carbon dioxide (for example, the atmosphere).
　第２アミン成分の中でも、２つのＡがいずれも炭素数２のエチレン基であるＮ－（２－アミノエチル）－２－アミノエタノール（以下、「ＡＥＡＥ」とも称する。）は、二酸化炭素の吸収速度が速く、二酸化炭素の吸収性能にも優れている。また、ＡＥＡＥは、沸点（約２４４℃）が高く、安定でロスが生じにくいことに加え、ＡＥＡＥは水に対する溶解度が非常に高い。第２アミン成分中のＡＥＡＥの含有率は、例えば、７０質量％以上が好ましく、８０質量％以上が好ましく、９０質量％以上（もしくは１００％）でもよい。 Among the secondary amine components, N-(2-aminoethyl)-2-aminoethanol (hereinafter also referred to as “AEAE”), in which both A are ethylene groups having 2 carbon atoms, absorbs carbon dioxide. It is fast and has excellent carbon dioxide absorption performance. In addition, AEAE has a high boiling point (about 244° C.), is stable and hardly causes loss, and has very high solubility in water. The content of AEAE in the secondary amine component is, for example, preferably 70% by mass or more, preferably 80% by mass or more, and may be 90% by mass or more (or 100%).
　アミン水溶液に含まれるアミン化合物（全てのアミン化合物の合計）の含有率（以下、「総アミン量」とも称する。）は、例えば、特に限定されないが、２０質量％～６０質量％であり、３０質量％～６０質量％でもよく、３０～５５質量％でもよく、４０質量％～５５質量％でもよい。総アミン量が６０質量％以下である場合、活性剤としての水の効果が向上すると考えられ、二酸化炭素の吸収量が増大しやすく、第１アミン成分と第２アミン成分との混合性が良好になる。また、アミン水溶液の粘度も低く維持される。また、総アミン量が２０質量％以上（更には３０質量％以上）である場合、アミン水溶液の単位体積あたりの二酸化炭素の吸収性能を十分に大きくできるため、二酸化炭素の回収をより効率的に行うことができる。 The content of the amine compound (total of all amine compounds) contained in the amine aqueous solution (hereinafter also referred to as "total amine amount") is not particularly limited, but is, for example, 20% by mass to 60% by mass, and 30% by mass. It may be from 30 to 55% by mass, or from 40 to 55% by mass. When the total amine content is 60% by mass or less, it is believed that the effect of water as an activator is improved, the amount of carbon dioxide absorbed is likely to increase, and the miscibility between the primary amine component and the secondary amine component is good. become. Also, the viscosity of the aqueous amine solution is kept low. In addition, when the total amine content is 20% by mass or more (further 30% by mass or more), the carbon dioxide absorption performance per unit volume of the amine aqueous solution can be sufficiently increased, so that carbon dioxide can be recovered more efficiently. It can be carried out.
　アミン化合物に含まれる第２アミン成分の含有率（Ｃ２）は、アミン化合物に含まれる第１アミン成分（ＩＰＡＥ）の含有率（Ｃ１）よりも大きくてもよい。この場合、特に５ｋＰａ未満（更には２ｋＰａ以下、もしくは１ｋＰａ以下）の分圧で二酸化炭素を含むガスを対象とする場合に、アミン水溶液による二酸化炭素の吸収速度が速くなり、より効率的に二酸化炭素を回収できるようになる。第２アミン成分の含有率Ｃ２の第１アミン成分（ＩＰＡＥ）の含有率Ｃ１に対する比：Ｃ２／Ｃ１は、例えば、１．５～３でもよく、２～３でもよく、２～２．５でもよい。 The content (C2) of the secondary amine component contained in the amine compound may be greater than the content (C1) of the primary amine component (IPAE) contained in the amine compound. In this case, especially when the target is a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less), the absorption rate of carbon dioxide by the amine aqueous solution increases, and carbon dioxide is more efficiently absorbed. can be recovered. The ratio of the content C2 of the secondary amine component to the content C1 of the primary amine component (IPAE): C2/C1 may be, for example, 1.5 to 3, 2 to 3, or 2 to 2.5. good.
　より具体的には、アミン水溶液に含まれる第１アミン成分（ＩＰＡＥ）の含有率は、例えば、５質量％以上、３０質量％未満であり、１０質量％以上、２５質量％以下でもよい。 More specifically, the content of the primary amine component (IPAE) contained in the amine aqueous solution is, for example, 5% by mass or more and less than 30% by mass, and may be 10% by mass or more and 25% by mass or less.
　また、アミン水溶液に含まれる第２アミン成分の含有率は、例えば、１５質量％以上、５５質量％以下であり、２５質量％以上、５０質量％以下でもよく、３０質量％以上、４５質量％以下でもよい。 Further, the content of the secondary amine component contained in the aqueous amine solution is, for example, 15% by mass or more and 55% by mass or less, may be 25% by mass or more and 50% by mass or less, or may be 30% by mass or more and 45% by mass. It can be below.
　なお、必ずしもＣ２＞Ｃ１である必要はなく、アミン化合物に含まれる第２アミン成分の含有率（Ｃ２）は、アミン化合物に含まれる第１アミン成分（ＩＰＡＥ）の含有率（Ｃ１）よりも小さくてもよく、Ｃ１＝Ｃ２でもよい。この場合、アミン水溶液による二酸化炭素の吸収性能および脱離性能を更に向上させることができる。また、Ｃ２／Ｃ１比が０．０５程度であっても、第２アミン成分による二酸化炭素の吸収速度の向上効果が見られる。Ｃ２／Ｃ１比が０．０５以上、更には０．１以上では、より安定した向上が見られる。 It should be noted that C2>C1 does not necessarily hold, and the content (C2) of the secondary amine component contained in the amine compound is smaller than the content (C1) of the primary amine component (IPAE) contained in the amine compound. or C1=C2. In this case, the carbon dioxide absorption performance and desorption performance of the aqueous amine solution can be further improved. Even when the C2/C1 ratio is about 0.05, the effect of improving the rate of absorption of carbon dioxide by the secondary amine component is observed. At C2/C1 ratios of 0.05 and above, and even 0.1 and above, more stable improvements are seen.
　アミン水溶液には、様々な添加剤を含ませてもよい。例えば、設備の腐食を防止するためのリン酸系防食剤、泡立ち防止のためのシリコーン系消泡剤、アミン化合物の劣化防止のための酸化防止剤等をアミン水溶液に添加してもよい。 The aqueous amine solution may contain various additives. For example, a phosphoric acid anticorrosive agent for preventing corrosion of equipment, a silicone antifoaming agent for preventing foaming, an antioxidant for preventing deterioration of the amine compound, and the like may be added to the aqueous amine solution.
　以上のように、アミン水溶液は、低濃度で二酸化炭素を含むガスから二酸化炭素を回収するのに適している。すなわち、第１工程は、二酸化炭素を分圧５ｋＰａ未満（更には２ｋＰａ以下、もしくは１ｋＰａ以下）で含むガスをアミン水溶液に接触させて、アミン水溶液に二酸化炭素を吸収させる工程であってもよい。 As described above, the aqueous amine solution is suitable for recovering carbon dioxide from gases containing carbon dioxide at low concentrations. That is, the first step may be a step of bringing a gas containing carbon dioxide at a partial pressure of less than 5 kPa (further, 2 kPa or less, or 1 kPa or less) into contact with the aqueous amine solution to absorb the carbon dioxide in the aqueous amine solution.
　二酸化炭素を分圧５ｋＰａ未満で含むガスは、大気であってもよい。すなわち、本開示がＤＡＣ（Ｄｉｒｅｃｔ　Ａｉｒ　Ｃａｐｔｕｒｅ）に適用してもよい。二酸化炭素を分圧５ｋＰａ未満で含むガスは、密閉空間において人の呼吸、機器のエネルギー変換等で排出される二酸化炭素を含むガスであってもよい。密閉空間としては、潜水調査船、宇宙ステーション、ビル、オフィス等の室内空間等が挙げられる。 The gas containing carbon dioxide at a partial pressure of less than 5 kPa may be the atmosphere. That is, the present disclosure may be applied to DAC (Direct Air Capture). The gas containing carbon dioxide at a partial pressure of less than 5 kPa may be a gas containing carbon dioxide that is emitted in a closed space by human breathing, energy conversion by equipment, or the like. Examples of closed spaces include indoor spaces such as submersible research vessels, space stations, buildings, and offices.
　二酸化炭素を含むガスは、より高濃度の二酸化炭素を含んでもよい。二酸化炭素を含むガスは、例えば、石炭、重油、天然ガス等を燃料とする火力発電所、コークスで酸化鉄を還元する製鐵所の高炉、銑鉄中の炭素を燃焼して製鋼する製鐵所の転炉、各種製造所におけるボイラー、セメント工場におけるキルン等、ガソリン、重油、軽油等を燃料とする自動車、船舶、航空機等の輸送機器から排出される排ガスであってもよい。 A gas containing carbon dioxide may contain a higher concentration of carbon dioxide. Gases containing carbon dioxide are used, for example, in thermal power plants that use coal, heavy oil, natural gas, etc. as fuel, blast furnaces in steel plants that reduce iron oxide with coke, and steel plants that burn carbon in pig iron to make steel. converters, boilers in various manufacturing plants, kilns in cement plants, etc., and exhaust gases emitted from transportation equipment such as automobiles, ships, and aircraft that use gasoline, heavy oil, light oil, etc. as fuel.
　第１工程では、二酸化炭素を含むガスを、例えば６０℃以下（更には５０℃以下、もしくは４５℃以下）の温度のアミン水溶液に接触させてもよく、好ましくは２０℃～４５℃のアミン水溶液に接触させてもよい。これにより、アミン水溶液への二酸化炭素の吸収を促進することができる。 In the first step, the gas containing carbon dioxide may be brought into contact with an aqueous amine solution at a temperature of, for example, 60°C or lower (further 50°C or lower, or 45°C or lower), preferably 20°C to 45°C. may come into contact with This can promote the absorption of carbon dioxide into the aqueous amine solution.
　二酸化炭素を含むガスをアミン水溶液に接触させる方法としては、例えば、アミン水溶液に二酸化炭素を含むガスをバブリングさせる方法、二酸化炭素を含むガス気流中にアミン水溶液を噴霧もしくはスプレーする方法、吸収塔内で二酸化炭素を含むガスとアミン水溶液とを向流接触させる方法などによって行い得る。 Examples of the method of contacting a gas containing carbon dioxide with an aqueous amine solution include a method of bubbling a gas containing carbon dioxide into an aqueous amine solution, a method of atomizing or spraying an aqueous amine solution into a gas stream containing carbon dioxide, and a method of spraying an aqueous amine solution into a gas stream containing carbon dioxide. It can be carried out by a method of contacting a gas containing carbon dioxide and an aqueous amine solution in a countercurrent manner.
　第１工程において、二酸化炭素を含むガスの圧力は、ほぼ大気圧で行ってもよい。吸収性能を高めるために、より高い圧力までガスを加圧してもよい。ガスの圧縮に要するエネルギー消費を抑える観点からは、大気圧下で第１工程を行うことが好ましい。 In the first step, the pressure of the gas containing carbon dioxide may be approximately atmospheric pressure. The gas may be pressurized to higher pressures to enhance absorption performance. From the viewpoint of suppressing energy consumption required for gas compression, it is preferable to perform the first step under atmospheric pressure.
　第２工程では、二酸化炭素を吸収させたアミン水溶液を、例えば７０℃以上の温度に加熱してもよい。アミン水溶液の温度が高くなるほど、二酸化炭素がアミン水溶液から脱離しやすい。二酸化炭素を吸収させたアミン水溶液を、８０℃以上、更には９０℃以上、好ましくは９０～１２０℃に加熱してもよい。これにより、アミン水溶液からの二酸化炭素の脱離を促進することができる。なお、本実施形態に係るアミン水溶液の沸点は１２０℃以上になり得るため、大気圧下でも沸騰させずに１２０℃に加熱することができる。 In the second step, the carbon dioxide-absorbed amine aqueous solution may be heated, for example, to a temperature of 70°C or higher. The higher the temperature of the aqueous amine solution, the easier it is for carbon dioxide to desorb from the aqueous amine solution. The carbon dioxide-absorbed amine aqueous solution may be heated to 80°C or higher, further 90°C or higher, preferably 90 to 120°C. This can promote desorption of carbon dioxide from the aqueous amine solution. In addition, since the boiling point of the aqueous amine solution according to the present embodiment can be 120° C. or higher, it can be heated to 120° C. without boiling even under atmospheric pressure.
　第２工程では、二酸化炭素を吸収させたアミン水溶液を、蒸留と同じように加熱して釜で泡立てて二酸化炭素を脱離させる方法、棚段塔、スプレー塔、磁製や金属網製の充填材の入った脱離塔内で液接触界面を広げて加熱する方法などを採用してもよい。これにより、カルバミン酸アニオンまたは重炭酸イオンから二酸化炭素が遊離して放出される。 In the second step, the carbon dioxide-absorbed amine aqueous solution is heated in the same manner as distillation and bubbled in a kettle to desorb carbon dioxide. A method of heating by widening the liquid contact interface in the desorption tower containing the material may be employed. This liberates carbon dioxide from the carbamate or bicarbonate ions.
　二酸化炭素を脱離させるときのアミン水溶液の雰囲気の圧力は、ほぼ大気圧で行ってよい。二酸化炭素の脱離を促進するために雰囲気を減圧してもよい。釜、棚段塔、スプレー塔、脱離塔などの内空間で二酸化炭素を脱離させる場合は、内空間の圧力を大気圧より高めてもよい。 The pressure of the atmosphere of the aqueous amine solution when desorbing carbon dioxide may be approximately atmospheric pressure. The atmosphere may be depressurized to facilitate desorption of carbon dioxide. When desorbing carbon dioxide in the inner space of a kettle, plate tower, spray tower, desorption tower, etc., the pressure in the inner space may be higher than the atmospheric pressure.
　二酸化炭素を脱離した後のアミン水溶液は、再び第１工程で二酸化炭素を吸収させるために循環使用される。 The aqueous amine solution after desorbing carbon dioxide is recycled to absorb carbon dioxide again in the first step.
　回収された二酸化炭素の純度は、例えば、９５～９９．９体積％程度と極めて高くなり得る。高濃度の二酸化炭素は、化学品、高分子物質の合成原料、食品冷凍用の冷剤等として用い得る。その他、回収した二酸化炭素を、現在技術開発されつつある地下等へ隔離貯蔵することも可能である。 The purity of the recovered carbon dioxide can be extremely high, for example, about 95-99.9% by volume. High-concentration carbon dioxide can be used as a raw material for synthesizing chemicals, polymeric substances, refrigerants for food freezing, and the like. In addition, it is also possible to isolate and store the recovered carbon dioxide underground, for which technology is currently being developed.
［実施例］
　次に、本開示について実施例と比較例を用いて更に具体的に説明するが、本開示は以下の実施例に限定されない。実施例で使用した薬品は、いずれも東京化成工業株式会社製の試薬である。 [Example]
Next, the present disclosure will be described more specifically using examples and comparative examples, but the present disclosure is not limited to the following examples. All chemicals used in the examples are reagents manufactured by Tokyo Kasei Kogyo Co., Ltd.
《実施例１》
　アミン水溶液の温度が４０℃になるように設定した恒温水槽内に、ガラス製のガス吸収ビンを浸し、ビン内に、ＩＰＡＥを１５質量％、ＡＥＡＥを３５質量％、水５０質量％を含むアミン水溶液Ａ１（合計１００％）５０ｍＬを充填した。アミン水溶液Ａ１中に、目の粗さ１００μｍ、直径１３ｍｍのガラスフィルターを通して、分圧（ＰＣＯ２）が１ｋＰａの二酸化炭素と窒素との混合ガスを０．７リットル／分でバブリングさせて、二酸化炭素をアミン水溶液Ａ１に吸収させた。 <<Example 1>>
A glass gas absorption bottle was immersed in a constant temperature water bath set so that the temperature of the aqueous amine solution was 40° C., and an amine containing 15% by mass of IPAE, 35% by mass of AEAE, and 50% by mass of water was placed in the bottle. 50 mL of aqueous solution A1 (total 100%) was charged. A mixed gas of carbon dioxide and nitrogen having a partial pressure (P CO2 ) of 1 kPa was bubbled at 0.7 liter/min through a glass filter having a mesh size of 100 μm and a diameter of 13 mm into the aqueous amine solution A1 to remove carbon dioxide. was absorbed in aqueous amine solution A1.
　ガス吸収ビンの混合ガスの入口および出口でガスを捕集して、ガス中の二酸化炭素濃度を、赤外線式の二酸化炭素計（ＨＯＲＩＢＡ　ＧＡＳ　ＡＮＡＬＹＺＥＲ　ＶＡ－３０００）で連続的に測定して、入口および出口の二酸化炭素流量の差から二酸化炭素の吸収量をモニタリングした。 Gas is collected at the inlet and outlet of the mixed gas of the gas absorption bottle, and the carbon dioxide concentration in the gas is continuously measured with an infrared carbon dioxide meter (HORIBA GAS ANALYZER VA-3000). The amount of carbon dioxide absorbed was monitored from the difference in the carbon dioxide flow rate at the outlet.
　出口の二酸化炭素濃度が入口の二酸化炭素濃度に一致する時点における二酸化炭素の吸収量を飽和吸収量とした。 The absorption amount of carbon dioxide at the time when the carbon dioxide concentration at the outlet matches the carbon dioxide concentration at the inlet was taken as the saturated absorption amount.
　次に、同じガス気流中で、二酸化炭素を飽和状態まで吸収させたアミン水溶液Ａ１の温度を大気圧下で１２０℃に昇温し、アミン水溶液Ａ１から二酸化炭素を脱離させた。ガス吸収ビン内は二酸化炭素で満たされた状態であり、従って１２０℃における二酸化炭素の分圧（ＰＣＯ２）は概ね１００ｋＰａであった。 Next, in the same gas stream, the temperature of the amine aqueous solution A1 in which carbon dioxide had been absorbed to a saturated state was raised to 120° C. under atmospheric pressure to desorb carbon dioxide from the amine aqueous solution A1. The gas absorption bottle was filled with carbon dioxide, so the partial pressure of carbon dioxide (P CO2 ) at 120° C. was approximately 100 kPa.
　４０℃で二酸化炭素を飽和状態まで吸収させたアミン水溶液Ａ１と、１２０℃で二酸化炭素を脱離させた後のアミン水溶液Ａ１の無機炭素量をガスクロマトグラフ式の全有機炭素計（ＳＨＩＭＡＤＺＵ　ＴＯＣ－ＶＣＳＨ）で測定し、それぞれの二酸化炭素の吸収量を求めた。 A gas chromatograph-type total organic carbon meter (SHIMADZU TOC-VCSH) was used to measure the amount of inorganic carbon in the aqueous amine solution A1 in which carbon dioxide was absorbed to a saturated state at 40°C and in the aqueous amine solution A1 after desorption of carbon dioxide at 120°C. ) to determine the absorption amount of each carbon dioxide.
　表１に、二酸化炭素の吸収速度と、４０℃での二酸化炭素の飽和吸収量（Ｍ_ｒｉｃｈ）と、１２０℃で二酸化炭素を脱離させた後の二酸化炭素の吸収量（Ｍ_ｌｅａｎ）と、これらの差から求めた二酸化炭素の回収量（ローディング量、Ｍ_ｒｉｃｈ－Ｍ_ｌｅａｎ）を示す。吸収量は単位体積（１Ｌ）のアミン水溶液に吸収される二酸化炭素の質量（ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．）で示す。 Table 1 shows the absorption rate of carbon dioxide, the saturated absorption amount of carbon dioxide at 40 ° C. (M_rich), the absorption amount of carbon dioxide after desorbing carbon dioxide at 120 ° C. (M_lean), and these The carbon dioxide recovery amount (loading amount, M_rich−M_lean) obtained from the difference is shown. The absorption amount is indicated by the mass (g-CO 2 /L-soln.) of carbon dioxide absorbed by a unit volume (1 L) of the amine aqueous solution.
《比較例１》
　ＩＰＡＥを３０質量％、ピペラジン（ＰＺ）を２０質量％、水５０質量％を含むアミン水溶液Ｂ１（合計１００％）５０ｍＬをガス吸収ビンに充填したこと以外、実施例１と同様の測定を行った。結果を表１に示す。 <<Comparative Example 1>>
The same measurement as in Example 1 was performed except that 50 mL of an aqueous amine solution B1 containing 30% by mass of IPAE, 20% by mass of piperazine (PZ), and 50% by mass of water (total 100%) was filled in a gas absorption bottle. . Table 1 shows the results.
《比較例２》
　モノエタノールアミン（ＭＥＡ）を３０質量％、水７０質量％を含むアミン水溶液Ｃ１（合計１００％）５０ｍＬをガス吸収瓶に充填したこと以外、実施例１と同様の測定を行った。結果を表１に示す。 <<Comparative Example 2>>
The same measurement as in Example 1 was performed except that 50 mL of an amine aqueous solution C1 (100% in total) containing 30% by mass of monoethanolamine (MEA) and 70% by mass of water was filled in a gas absorption bottle. Table 1 shows the results.
Figure JPOXMLDOC01-appb-T000011
  
Figure JPOXMLDOC01-appb-T000011
  
　表１の結果を考慮すると、アミン水溶液Ａ１の場合、１１２．８ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．から１４３．３ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．の範囲（ローディング領域）が１回の吸収と脱離のサイクルで回収される二酸化炭素量（ローディング量）に対応する。一方、アミン水溶液Ｂ１の場合、９１．１ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．から１２７．２ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．の範囲（ローディング領域）が、アミン水溶液Ｃ１の場合、８３．１ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．から９７．３ｇ-ＣＯ2／Ｌ-ｓｏｌｎ．の範囲（ローディング領域）が、１回の吸収と脱離のサイクルで回収される二酸化炭素量（ローディング量）に対応する。 Considering the results in Table 1, in the case of the amine aqueous solution A1, 112.8 g-CO 2 /L-soln. to 143.3 g- CO2 /L-soln. (loading area) corresponds to the amount of carbon dioxide recovered in one absorption and desorption cycle (loading amount). On the other hand, in the case of amine aqueous solution B1, 91.1 g-CO 2 /L-soln. to 127.2 g- CO2 /L-soln. (loading area) is 83.1 g-CO 2 /L-soln. to 97.3 g- CO2 /L-soln. (loading area) corresponds to the amount of carbon dioxide (loading) recovered in one absorption-desorption cycle.
　次に、図１に、４０℃における二酸化炭素の吸収量（Ａｂｓｏｒｐｔｉｏｎａｍｏｕｎｔ（ｇ／Ｌ－ｓｏｌｎ．））と吸収速度（Ａｂｓｏｒｐｔｉｏｎｒａｔｅ（ｇ-ＣＯ２／Ｌ／ｍｉｎ．））との関係を示す。図１から、アミン水溶液Ａ１の場合、ローディング領域における吸収速度があまり変化せず、高い吸液速度を維持できることが理解できる。一方、アミン水溶液Ｂ１の場合、ローディング領域において吸収速度が急低下することが理解できる。また、アミン水溶液Ｃ１の場合、ローディング領域において吸収速度が急低下し、ローディング量も少ないことが理解できる。 Next, FIG. 1 shows the relationship between the absorption amount of carbon dioxide (Absorption amount (g/L-soln.)) at 40° C. and the absorption rate (Absorption rate (g-CO 2 /L/min.)). From FIG. 1, it can be understood that in the case of the amine aqueous solution A1, the absorption rate in the loading area does not change much, and a high liquid absorption rate can be maintained. On the other hand, in the case of the aqueous amine solution B1, it can be understood that the absorption rate drops sharply in the loading region. Moreover, in the case of the amine aqueous solution C1, it can be understood that the absorption rate drops sharply in the loading region and the loading amount is small.
　実用上の要請を考慮する場合、二酸化炭素の吸収と脱離を繰り返して二酸化炭素を回収するタクトタイムは短いほど望ましい。アミン水溶液Ａ１は、ローディング領域で迅速に二酸化炭素を吸収し、放出するため、アミン水溶液Ｂ１、Ｃ１よりもタクトタイムが相当に短くなる。すなわち、アミン水溶液Ａ１のようなアミン水溶液を用いることで、二酸化炭素を低コストで効率的に回収することができるようになるといえる。 When considering practical requirements, the shorter the tact time for collecting carbon dioxide by repeating the absorption and desorption of carbon dioxide, the better. Since the aqueous amine solution A1 rapidly absorbs and releases carbon dioxide in the loading area, the tact time is significantly shorter than the aqueous amine solutions B1 and C1. That is, it can be said that carbon dioxide can be efficiently recovered at low cost by using an aqueous amine solution such as the aqueous amine solution A1.
　本開示に係る二酸化炭素を回収する方法によれば、ガス中の二酸化炭素を低コストで効率的に回収することが可能である。本開示に係るアミン水溶液によれば、ガス中の二酸化炭素の分圧が小さい場合でも二酸化炭素を高濃度まで速やかに吸収することができる。本開示は、例えば、大気中から二酸化炭素を回収するＤＡＣ（Ｄｉｒｅｃｔ　Ａｉｒ　Ｃａｐｔｕｒｅ）の実用化に適する。 According to the method for recovering carbon dioxide according to the present disclosure, it is possible to efficiently recover carbon dioxide in gas at low cost. According to the aqueous amine solution according to the present disclosure, even when the partial pressure of carbon dioxide in gas is low, carbon dioxide can be rapidly absorbed to a high concentration. The present disclosure is suitable for practical use of, for example, a DAC (Direct Air Capture) that recovers carbon dioxide from the atmosphere.
　本発明を現時点での好ましい実施態様に関して説明したが、そのような開示を限定的に解釈してはならない。種々の変形および改変は、上記開示を読むことによって本発明に属する技術分野における当業者には間違いなく明らかになるであろう。したがって、添付の請求の範囲は、本発明の真の精神および範囲から逸脱することなく、すべての変形および改変を包含する、と解釈されるべきものである。
  While the invention has been described in terms of presently preferred embodiments, such disclosure is not to be construed in a limiting sense. Various alterations and modifications will no doubt become apparent to those skilled in the art to which the invention pertains after reading the above disclosure. Therefore, the appended claims are to be interpreted as covering all variations and modifications without departing from the true spirit and scope of the invention.

Claims (8)

  1. 　二酸化炭素を含むガスから二酸化炭素を回収する方法であって、
    　アミン化合物を含むアミン水溶液に二酸化炭素を吸収させる第１工程と、
    　前記二酸化炭素を吸収させた前記アミン水溶液を加熱して前記二酸化炭素を水溶液から脱離させて回収する第２工程と、を含み、
    　前記アミン化合物が、
    　第１アミン成分として、式（I）：
    Figure JPOXMLDOC01-appb-C000001
      
    で表される２－イソプロピルアミノエタノールを含み、かつ
    　第２アミン成分として、一般式（II）：
    Figure JPOXMLDOC01-appb-C000002
      
    で表されるアルカノールアミンを含み、
    　前記一般式（II）中、２つのＡは、それぞれ炭素数２～４のアルキレン基を示し、かつ互いに同一でも異なってもよい、二酸化炭素の回収方法。     A method for recovering carbon dioxide from a gas containing carbon dioxide, comprising:
    A first step of absorbing carbon dioxide in an aqueous amine solution containing an amine compound;
    a second step of heating the aqueous amine solution in which the carbon dioxide has been absorbed to desorb and recover the carbon dioxide from the aqueous solution;
    The amine compound is
    As the primary amine component, the formula (I):
    Figure JPOXMLDOC01-appb-C000001
    and containing 2-isopropylaminoethanol represented by the general formula (II) as a secondary amine component:
    Figure JPOXMLDOC01-appb-C000002
    containing an alkanolamine represented by
    A method for recovering carbon dioxide, wherein in the general formula (II), two A's each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different.
  2. 　前記第２アミン成分が、前記２つのＡがいずれもエチレン基であるＮ－（２－アミノエチル）－２－アミノエタノールである、請求項１に記載の二酸化炭素の回収方法。 The method for recovering carbon dioxide according to claim 1, wherein the secondary amine component is N-(2-aminoethyl)-2-aminoethanol in which the two A are both ethylene groups.
  3. 　前記アミン水溶液に含まれる前記アミン化合物の含有率が、２０質量％以上、６０質量％以下である、請求項１または２に記載の二酸化炭素の回収方法。 The method for recovering carbon dioxide according to claim 1 or 2, wherein the content of the amine compound contained in the aqueous amine solution is 20% by mass or more and 60% by mass or less.
  4. 　前記アミン化合物に含まれる前記第２アミン成分の含有率が、前記アミン化合物に含まれる前記第１アミン成分の含有率よりも大きい、請求項１～３のいずれか１項に記載の二酸化炭素の回収方法。 Carbon dioxide according to any one of claims 1 to 3, wherein the content of the secondary amine component contained in the amine compound is higher than the content of the primary amine component contained in the amine compound. collection method.
  5. 　前記アミン水溶液に含まれる前記第１アミン成分の含有率が、５質量％以上、３０質量％未満である、請求項１～４のいずれか１項に記載の二酸化炭素の回収方法。 The method for recovering carbon dioxide according to any one of claims 1 to 4, wherein the content of the primary amine component contained in the aqueous amine solution is 5% by mass or more and less than 30% by mass.
  6. 　前記第１工程において、二酸化炭素を分圧５ｋＰａ未満で含むガスを前記アミン水溶液に接触させて、前記アミン水溶液に前記二酸化炭素を吸収させる、請求項１～５のいずれか１項に記載の二酸化炭素の回収方法。 The dioxide according to any one of claims 1 to 5, wherein in the first step, a gas containing carbon dioxide at a partial pressure of less than 5 kPa is brought into contact with the aqueous amine solution to cause the aqueous amine solution to absorb the carbon dioxide. Carbon recovery method.
  7. 　前記第１工程において、前記ガスを６０℃以下の温度の前記アミン水溶液に接触させ、かつ前記第２工程において、前記二酸化炭素を吸収させた前記アミン水溶液を７０℃以上の温度に加熱する、請求項６に記載の二酸化炭素の回収方法。 In the first step, the gas is brought into contact with the aqueous amine solution having a temperature of 60°C or lower, and in the second step, the aqueous amine solution in which the carbon dioxide is absorbed is heated to a temperature of 70°C or higher. 7. The method for recovering carbon dioxide according to Item 6.
  8. 　二酸化炭素を含むガスから二酸化炭素を回収するアミン水溶液であって、
    　前記アミン水溶液は、アミン化合物を含み、
    　前記アミン化合物が、
    　第１アミン成分として、式（I）：
    Figure JPOXMLDOC01-appb-C000003
      
    で表される２－イソプロピルアミノエタノールを含み、かつ
    　第２アミン成分として、一般式（II）：
    Figure JPOXMLDOC01-appb-C000004
      
    で表されるアルカノールアミンを含み、
    　前記一般式（II）中、２つのＡは、それぞれ炭素数２～４のアルキレン基を示し、かつ互いに同一でも異なってもよい、二酸化炭素を回収するためのアミン水溶液。
          An aqueous amine solution for recovering carbon dioxide from a gas containing carbon dioxide,
    The aqueous amine solution contains an amine compound,
    The amine compound is
    As the primary amine component, the formula (I):
    Figure JPOXMLDOC01-appb-C000003
    and containing 2-isopropylaminoethanol represented by the general formula (II) as a secondary amine component:
    Figure JPOXMLDOC01-appb-C000004
    containing an alkanolamine represented by
    An aqueous amine solution for recovering carbon dioxide, wherein two A's in the general formula (II) each represent an alkylene group having 2 to 4 carbon atoms and may be the same or different.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10202053A (en) * 1997-01-27 1998-08-04 Mitsubishi Heavy Ind Ltd Method of reducing amine mist in decarbonation column
WO2009001804A1 (en) * 2007-06-28 2008-12-31 Research Institute Of Innovative Technology For The Earth Method for efficiently recovering carbon dioxide in gas
KR20110032940A (en) * 2009-09-24 2011-03-30 한국전력공사 Absorbents for separation of acidic gas
JP2017031046A (en) * 2015-07-29 2017-02-09 国立大学法人金沢大学 Absorber and generator of carbon dioxide derived from air
JP2020069415A (en) * 2018-10-30 2020-05-07 東ソー株式会社 Carbon dioxide separating composition

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10202053A (en) * 1997-01-27 1998-08-04 Mitsubishi Heavy Ind Ltd Method of reducing amine mist in decarbonation column
WO2009001804A1 (en) * 2007-06-28 2008-12-31 Research Institute Of Innovative Technology For The Earth Method for efficiently recovering carbon dioxide in gas
KR20110032940A (en) * 2009-09-24 2011-03-30 한국전력공사 Absorbents for separation of acidic gas
JP2017031046A (en) * 2015-07-29 2017-02-09 国立大学法人金沢大学 Absorber and generator of carbon dioxide derived from air
JP2020069415A (en) * 2018-10-30 2020-05-07 東ソー株式会社 Carbon dioxide separating composition

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