CARBON DIOXIDE ABSORBING COMPOSITION COMPRISING IONIC BASE CONTAINING SPIROAmmonium CATION, AND METHOD FOR SEPARATING CARBON

Abstract

The present invention provides a carbon dioxide absorbing composition containing an ionic substance containing a spiroammonium cation and a method for separating carbon dioxide using the carbon dioxide absorbing composition, the carbon dioxide absorbing composition of the present invention having high thermal stability and chemical stability and having an excellent carbon dioxide absorbing effect. In addition, the method for separating carbon dioxide using the carbon dioxide absorbing composition is very effective for desorption of carbon dioxide, and the carbon dioxide absorbing composition can be reused, thus being a very economical method.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide absorbing composition comprising an ionic substance containing spiroammonium cations and a method for separating carbon dioxide using the carbon dioxide absorbing composition. Background Art

[0002] Due to the rapid advancement of economic development and industrialization worldwide, the use of fossil fuels, which are the main source of energy, has continued to increase. In particular, carbon dioxide (CO2) is known to account for the largest proportion of the main greenhouse gases formed in the process of burning fossil fuels to convert them into energy, and is closely related to the problem of global warming. Due to the increase and long-term use of energy, the problem of global warming has intensified and has attracted worldwide attention. In order to solve this problem, research fields related to carbon dioxide have also become important.

[0003] Methods for separating carbon dioxide from waste gas and natural gas from chemical plants, power plants, and large boilers use absorption methods, adsorption methods, separation membrane methods, cryogenic separation methods, and the like. In particular, when the concentration of the emitted carbon dioxide is low, absorption methods or adsorption methods are generally used. The absorption method or adsorption method can selectively separate only part of the gas that is well absorbed or adsorbed by the absorbent or adsorbent, and is therefore widely used in industry, but the absorbent and adsorbent undergo chemical changes during the separation process, and therefore have the disadvantage of requiring regular replacement.

[0004] When solid adsorbents are used, chemical changes of the adsorbent are less, so it is advantageous to use solid adsorbents when the replacement cycle of the adsorbent is long. On the other hand, liquid absorbents are used in the absorption method, so it has the advantage of easy replacement of the absorbent, and is widely used in the purification of large amounts of waste gas or gas separation, but it has the disadvantage of chemical changes of the absorbent.

[0005] As a carbon dioxide absorbent, aqueous solutions of amines such as monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and diethanolamine (DEA) are generally the most widely used. This is because the weakly alkaline amine absorbent forms a chemical bond with carbon dioxide, which is an acidic gas. When heat is applied, the bond breaks, the carbon dioxide is degassed and recovered, and the absorbent can be regenerated.

[0006] However, there are several serious problems with the process using an aqueous amine solution. In particular, the following disadvantages have been pointed out: the high temperature used in the regeneration step of the amine absorbent to break the chemical bond between carbon dioxide and the absorbent causes irreversible decomposition of the amine, SO contained in the absorption gas, and the like. x and NO xThe problems of irreversible decomposition of amines due to impurities such as amines, performance degradation of the absorbent and the problem of replenishing the absorbent due to the irreversible decomposition of the amines, corrosion of the absorption device due to the amines themselves or their decomposition products, and contamination of the regenerated gaseous carbon dioxide due to the vapor pressure of the absorbent, etc.

[0007] As an alternative to this, ionic liquids have been proposed. Ionic liquids are composed of cations and relatively small inorganic anions or organic anions, wherein the cations are quaternary ammonium, imidazolium, pyridinium, phosphonium ions, etc., and the inorganic anions are [Cl] - ,[Br] - , [I] - , [BF4] - , [PF6] - , [Tf2N] - etc., wherein the organic anion is [RCO2] - , [CO3] 2- Ionic liquids are also called "designer solvents" because they can be transformed into various properties through unlimited combinations of cations and anions and functional groups.

[0008] The imidazolium cation and [Cl] - , [BF4] - , [PF6] - , [CH3SO3] - , [CF3BF3] - , [C2F5BF3] - Many studies have been conducted on anionic liquids and synthesis using the anionic liquids. In the case of ionic liquids containing fluorine, high carbon dioxide absorption capacity can be expected. However, since they are difficult to biodegrade, they are harmful to the environment, and fluorine-containing anions are very expensive.

[0009] Therefore, it is necessary to develop an absorbent that is an ionic substance with optimal characteristics for the separation of carbon dioxide, has thermal stability so that there is no possibility of release into the atmosphere, and has chemical stability so that the release of decomposition products into the atmosphere can be reduced, and can desorb carbon dioxide with excellent efficiency without causing corrosion of the device. Summary of the invention

[0010] 1. Technical issues to be resolved

[0011] An object of the present invention is to provide a carbon dioxide absorbing composition which is not easily decomposed even under high temperature alkaline conditions and thus has high stability in a carbon dioxide desorption process.

[0012] The object of the present invention is to provide a carbon dioxide absorbing composition which has thermal and chemical stability, thereby reducing the release of decomposition products into the atmosphere when applied to a process and reducing the regeneration energy due to low vapor pressure.

[0013] Another object of the present invention is to provide a method for separating carbon dioxide in an environmentally friendly and economical manner using the carbon dioxide absorbing composition.

[0014] (II) Technical solution

[0015] The present invention provides a carbon dioxide absorbing composition, which includes an ionic substance, wherein the ionic substance includes a spiroammonium cation represented by the following Chemical Formula 1.

[0016] [Chemical formula 1]

[0017]

[0018] (In the chemical formula 1, L1 and L2 are each independently a single bond, -O-, -NR 13 -、 or (C1-C8) alkylene, L3 is a single bond, -O-, -NR 14 - or (C1-C8) alkylene, R1 to R 14 Each is independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, (C3-C20)cycloalkyl or (C2-C20)heterocycloalkyl.)

[0019] According to a specific embodiment, L1 and L2 in the chemical formula 1 can each independently be a single bond, -O-, -NR 13 - or (C1-C5) alkylene, R1 to R 14 Each may independently be hydrogen or (C1-C10) alkyl.

[0020] According to a specific embodiment, L1 and L2 in the chemical formula 1 can each independently be a single bond, -O-, -NR 13 - or (C1-C3) alkylene, R1 to R 14 Each may independently be hydrogen or (C1-C5) alkyl.

[0021] According to a specific embodiment, L1 of the Chemical Formula 1 may be a single bond, a methylene group, -O- or -N(CH3)-, and L2 may be a single bond or a methyl group.

[0022] The spiroammonium cation may be represented by Chemical Formula 2 below.

[0023] [Chemical formula 2]

[0024]

[0025] (In the chemical formula 2, L2 and L3 are each independently a single bond, -O-, -NR 13 - or (C1-C5) alkylene, wherein R1 to R 14 is hydrogen or (C1-C10) alkyl. )

[0026] According to a specific embodiment, L2 and L3 in the chemical formula 2 may each independently be a single bond or a (C1-C3) alkylene group, and R1 to R 14 It may be hydrogen or (C1-C5) alkyl.

[0027] According to a specific embodiment, L2 and L3 of the Chemical Formula 2 may be a single bond or a methylene group, and L2 and L3 may be the same as each other.

[0028] According to a specific embodiment, the spiroammonium cation may be selected from the following chemical formulae.

[0029]

[0030] The ionic substance in the carbon dioxide absorbing composition according to one specific embodiment of the present invention may include a phenoxide-based anion represented by the following Chemical Formula 3 or an imidazolium-based anion represented by the following Chemical Formula 4.

[0031] [Chemical formula 3]

[0032]

[0033] (In the chemical formula 3, R 21 To R 25 Each of them is independently hydrogen, amino, hydroxyl, nitro, amide, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, and the amino, hydroxyl, amide, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylamino, dialkylamino, alkylaminoalkyl and dialkylaminoalkyl may be substituted by one or more substituents selected from halogen, cyano, amino, nitro, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl and C1-C10 alkoxycarbonyl.)

[0034] [Chemical formula 4]

[0035]

[0036] (In the chemical formula 4, A1 to A4 are each independently CR or N, at least one of A1 to A4 is N, and R is hydrogen, amino, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylcarbonylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, or two or more Rs may be connected to each other to form a ring.)

[0037] The carbon dioxide absorbing composition may comprise water.

[0038] The carbon dioxide absorbing composition may further comprise one or more solvents other than water.

[0039] The carbon dioxide absorption equivalent represented by the following Formula 1 of the carbon dioxide absorbing composition according to one specific embodiment of the present invention may be 0.6 or more.

[0040] [Formula 1]

[0041] Carbon dioxide absorption equivalent = (number of moles of carbon dioxide absorbed) / (number of moles of ionic species in the absorption composition)

[0042] According to a specific embodiment, the carbon dioxide absorbing composition may further comprise one or more amine absorbents.

[0043] The carbon dioxide absorbing composition further comprising one or more of the amine absorbents may contain water.

[0044] The carbon dioxide absorbing composition may further comprise one or more solvents other than water.

[0045] According to a specific embodiment of the present invention, a method for separating carbon dioxide may include: a first step of contacting a carbon dioxide absorption composition according to a specific embodiment of the present invention with a mixture containing carbon dioxide; and a second step of heat-treating the carbon dioxide absorption composition to desorb carbon dioxide attached to the absorption composition.

[0046] The first step can be performed at 20-80°C.

[0047] The second step can be performed at 70-150°C.

[0048] According to a specific embodiment, the method for separating carbon dioxide may set the first step and the second step as a unit process, and repeat the unit process more than twice to continuously separate carbon dioxide.

[0049] (III) Beneficial effects

[0050] The carbon dioxide absorption composition according to the present invention has thermal stability and chemical stability, so when applied to a process, the release of decomposition products into the atmosphere can be reduced. Compared with the existing amine carbon dioxide absorption composition, it is not easy to decompose even under high temperature alkaline conditions, so it has thermal stability.

[0051] In addition, compared with the existing amine carbon dioxide absorbing composition, the carbon dioxide absorbing composition according to the present invention has low corrosivity, so that a carbon dioxide absorbing composition containing a high concentration of ionic substances can be prepared, and thus can show significantly improved absorption performance. In addition, compared with the existing amine carbon dioxide absorbing composition, the carbon dioxide absorbing composition of the present invention can easily desorb carbon dioxide even with low regeneration energy, and is therefore very effective in absorbing and desorbing carbon dioxide.

[0052] The method of separating carbon dioxide using the carbon dioxide absorbing composition according to the present invention can have improved absorption performance and stable process operation, and thus is a very economical and environmentally friendly method, and thus can be easily applied in industry. DETAILED DESCRIPTION

[0053] Hereinafter, the present invention will be described in detail. Unless otherwise defined, the terms used in this specification should be interpreted as what is generally understood by those skilled in the art. The embodiments of this specification are intended to enable those skilled in the art to easily understand and implement the present invention, and the contents that may make the gist of the present invention unclear may be omitted from the embodiments, and the present invention is not limited to the embodiments.

[0054] Unless otherwise specifically stated herein, a singular form used in the present specification may also include a plural form.

[0055] In addition, the numerical range used in this specification includes the lower limit value and the upper limit value and all values ​​within the range, the increments logically derived from the form and width of the defined range, all values ​​defined therein, and all possible combinations of the upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may appear due to experimental errors or rounding of values ​​are also included in the defined numerical range.

[0056] In this specification, terms such as “comprises,” “includes,” “contains,” “has,” and “equipped” refer to the existence of features or constituent elements recorded in the specification, and do not preclude the possibility of adding one or more other features or constituent elements unless otherwise specifically limited.

[0057] In this specification, the term "single bond" refers to the case where there is no atom at the corresponding position. For example, in the structure of XYZ, when Y is a single bond, X and Z are directly connected to form the structure of XZ.

[0058] The present invention provides a carbon dioxide absorbing composition, which includes an ionic substance, wherein the ionic substance includes a spiroammonium cation represented by Chemical Formula 1.

[0059] [Chemical formula 1]

[0060]

[0061] (In the chemical formula 1, L1 and L2 are each independently a single bond, -O-, -NR 13 -、 or (C1-C8) alkylene, L3 is a single bond, -O-, -NR 14 - or (C1-C8) alkylene, R1 to R 14 Each is independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, (C3-C20)cycloalkyl or (C2-C20)heterocycloalkyl.)

[0062] The carbon dioxide absorbing composition according to one embodiment of the present invention has thermal stability and chemical stability, so when applied to a process, the loss of the carbon dioxide absorbing composition caused by decomposition is low. Specifically, the spiroammonium cation and the phenolate anion or the imidazolium anion of the ionic substance constituting the carbon dioxide absorbing composition are not easily decomposed in the desorption process under high temperature and alkaline conditions, so that when applied to a process, the periodic replenishment of the absorbing composition can be reduced, and thus it is economical.

[0063] Amine absorbents (e.g., monoethanolamine (MEA)) used in existing carbon dioxide absorbing compositions have the advantage of fast reaction speed with carbon dioxide, but have the problem of high decomposition rate after carbon dioxide desorption process. In contrast, the carbon dioxide absorbing composition according to one embodiment of the present invention comprises an ionic substance comprising a spiroammonium cation and a phenolate anion or an imidazolate anion of a specific structure, and thus can reduce the decomposition rate after carbon dioxide desorption process compared with existing amine absorbents.

[0064] Compared with existing amine compounds, the ionic substance of the present invention has low corrosivity, so the ionic substance can be used to prepare a carbon dioxide absorption composition containing a high concentration of ionic substance, and compared with the existing carbon dioxide absorption composition containing amine compounds, the carbon dioxide absorption composition can have significantly improved carbon dioxide absorption performance.

[0065] Specifically, L1 and L2 in the chemical formula 1 according to one embodiment of the present invention may each independently be a single bond, -O-, -NR 13 - or (C1-C5) alkylene, R1 to R 14 Each may independently be hydrogen or (C1-C10) alkyl.

[0066] More specifically, L1 and L2 in the chemical formula 1 can each independently be a single bond, -O-, -NR 13 - or (C1-C3) alkylene, R1 to R 14 Each may independently be hydrogen or (C1-C5) alkyl.

[0067] More specifically, L1 of the Chemical Formula 1 may be a single bond, a methylene group, -O- or -N(CH3)-, and L2 may be a single bond or a methyl group.

[0068] The spiroammonium cation according to one embodiment of the present invention may be represented by Chemical Formula 2 below.

[0069] [Chemical formula 2]

[0070]

[0071] (In the chemical formula 2, L2 and L3 are each independently a single bond, -O-, -NR 13 - or (C1-C5) alkylene, wherein R1 to R 14 Each is independently hydrogen or (C1-C10) alkyl.)

[0072] Specifically, L2 and L3 of the chemical formula 2 according to one embodiment of the present invention may each independently be a single bond or a (C1-C3) alkylene group, and R1 to R 14 It may be hydrogen or (C1-C5) alkyl.

[0073] More specifically, L2 and L3 of the Chemical Formula 2 may be a single bond or a methylene group, and L2 and L3 may be the same as each other.

[0074] The spiroammonium cation according to one embodiment of the present invention may be selected from the following chemical formulae.

[0075]

[0076] In the carbon dioxide absorbing composition according to one specific embodiment of the present invention, the ionic substance may include a phenoxide-based anion represented by the following Chemical Formula 3 or an imidazolium-based anion represented by the following Chemical Formula 4.

[0077] [Chemical formula 3]

[0078]

[0079] (In the chemical formula 3, R 21 To R 25 Each of them is independently hydrogen, amino, hydroxyl, nitro, amide, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, and the amino, hydroxyl, amide, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylamino, dialkylamino, alkylaminoalkyl and dialkylaminoalkyl may be substituted by one or more substituents selected from halogen, cyano, amino, nitro, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl and C1-C10 alkoxycarbonyl.)

[0080] [Chemical formula 4]

[0081]

[0082] (In the chemical formula 4, A1 to A4 are each independently CR or N, at least one of A1 to A4 is N, and R is hydrogen, amino, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylcarbonylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, or two or more Rs may be connected to each other to form a ring.)

[0083] In the carbon dioxide absorbing composition according to one embodiment of the present invention, based on the total composition, 20-80 wt % of ionic substances may be included, specifically 25-77 wt % of ionic substances may be included, and more specifically 30-75 wt % of ionic substances may be included.

[0084] The carbon dioxide absorption composition may contain water, and may further contain one or more solvents other than water. The solvent other than water may be a non-aqueous solvent, and illustratively, the non-aqueous solvent may be one or more selected from ethylene glycol, propylene glycol, methyl glycol, methyl isopropyl carboxylate, methyl diethyl carboxylate, triethylene glycol, dimethyl sulfonate, and diethyl sulfonate, and may be ethylene glycol.

[0085] According to a specific embodiment, the carbon dioxide absorbing composition may contain 20-80 wt % of a mixed solvent of water and a non-aqueous solvent, more specifically, 23-75 wt % or 25-70 wt % of a mixed solvent of water and a non-aqueous solvent.

[0086] The carbon dioxide absorption equivalent represented by the following Formula 1 of the carbon dioxide absorbing composition according to one embodiment of the present invention may be 0.6 or more, preferably may be 0.65 to 3.0, and more preferably may be 0.7 to 3.0.

[0087] [Formula 1]

[0088] Carbon dioxide absorption equivalent = (number of moles of carbon dioxide absorbed) / (number of moles of ionic species in the absorption composition)

[0089] As for the carbon dioxide absorption mechanism of the ionic substance containing spiroammonium cations and phenolate anions or imidazolium anions according to one embodiment of the present invention, not only a chemical absorption method in which carbon dioxide reacts with the phenolate anions or imidazolium anions of the absorption composition to form carbonates and carbamates represented by Reaction Formulas 1 and 2, but also a physical absorption method in which carbon dioxide is captured in the "free volume" of the carbon dioxide absorption composition containing the ionic substance can show a more excellent carbon dioxide absorption equivalent.

[0090] [Reaction 1]

[0091] CO2+[heterocyclic-N + ][Phenol-O - ] → [Heterocyclic-N + ][Phenolate-O-CO2 - ]

[0092] [Reaction 2]

[0093] CO2+[heterocyclic-N + ][Imidazole salt-N - ] → [Heterocyclic-N + ][Imidazole salt-N-CO2 - ]

[0094] The carbon dioxide absorption composition containing the ionic substance according to one embodiment of the present invention is a combination of a spiroammonium cation substance with a specific structure and a phenolate anion or an imidazolium anion, which can show a significantly improved effect in terms of absorption equivalent compared with the existing amine carbon dioxide absorption composition.

[0095] The carbon dioxide absorbing composition according to one embodiment of the present invention may further comprise one or more amine absorbents, specifically, 1 to 5 or 1 to 3 amine absorbents. The amine absorbent may be selected from monoethanolamine (MEA), N-methyldiethanolamine (MDEA), diethanolamine (DEA), triethanolamine (TEA), 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ).

[0096] The carbon dioxide absorbing composition including the amine absorbent may further include water, and may further include one or more solvents other than water.

[0097] When the carbon dioxide absorbing composition including the ionic substance according to one embodiment of the present invention is stored for a long time at a heat treatment temperature for desorbing carbon dioxide attached to the absorbing composition, the reduction rate of the carbon dioxide absorbing composition is low, so that even after the carbon dioxide desorption process, the performance of the carbon dioxide absorbing composition can be stably maintained. The reduction rate of the carbon dioxide absorbing composition represented by the following formula 2 can be 5% or less, preferably 4.5% or less, and more preferably 4% or less.

[0098] [Formula 2]

[0099] Reduction rate of carbon dioxide absorbing composition = 100 - {(number of moles of ionic substances after heat treatment) / (number of moles of ionic substances before heat treatment)} × 100

[0100] The present invention provides a method for separating carbon dioxide using a carbon dioxide absorbing composition. Specifically, the method for separating carbon dioxide may include: a first step of contacting the carbon dioxide absorbing composition with a mixture containing carbon dioxide; and a second step of heat-treating the carbon dioxide absorbing composition to desorb the carbon dioxide attached to the absorbing composition.

[0101] In the method for separating carbon dioxide according to the present invention, the decomposition of the carbon dioxide absorbing composition is suppressed in the second step of desorbing carbon dioxide under high temperature and alkaline conditions, so that the reduction rate of the absorbing composition after desorption of carbon dioxide can be reduced. Therefore, compared with the existing method of absorbing carbon dioxide using an amine-based carbon dioxide absorbing composition, the method for separating carbon dioxide has less loss of the absorbing composition according to the number of processes, so that the amount of the absorbing composition to be supplemented after each process can be reduced, and thus the process can be operated more economically.

[0102] The first step of the method for separating carbon dioxide according to the present invention can be carried out at 20-80°C, specifically at 25°C to 65°C, more specifically at 30°C to 50°C, but is not limited thereto.

[0103] The second step of the method for separating carbon dioxide according to the present invention can be carried out at 70-150°C, specifically at 80°C to 140°C, more specifically at 90°C to 130°C, but is not limited thereto.

[0104] According to the method for separating carbon dioxide of the present invention, the first step and the second step may be set as a unit process, and the unit process may be repeated two or more times to continuously separate carbon dioxide.

[0105] The carbon dioxide absorbing composition according to the present invention has thermal stability and chemical stability, so the loss of the carbon dioxide absorbing composition caused by decomposition is also low. Therefore, based on the above reasons, the method of separating carbon dioxide of the present invention using the carbon dioxide absorbing composition has few by-products released into the atmosphere due to the decomposition of the absorbing composition, and can therefore be a very environmentally friendly method.

[0106] Furthermore, the method of separating carbon dioxide using the carbon dioxide absorbing composition according to the present invention has a low decomposition rate of the carbon dioxide absorbing composition after the carbon dioxide desorption process, so that the absorbing composition can be reused, and thus is a very economical method.

[0107] Hereinafter, the carbon dioxide absorbing composition comprising an ionic substance containing spiroammonium cations and the method for separating carbon dioxide using the carbon dioxide absorbing composition according to the present invention will be described in more detail through specific examples.

[0108] [Preparation Example 1] Preparation of ionic substance IC-1

[0109] 40 mmol of the cationic chloride of IC-1 in Table 1 below and 40 mmol of the anionic sodium compound of IC-1 in Table 1 below were added, and 40 mL of ethanol was added, followed by stirring at room temperature for 2 hours. The generated sodium chloride solid was filtered and removed, and vacuum dried at 50° C. for 15 hours to obtain an ionic substance IC-1. The obtained ionic substance IC-1 was subjected to NMR measurement, and the results are shown in Table 1.

[0110] [Preparation Example 2 to Preparation Example 9] Preparation of Ionic Substances IC-2 to IC-9

[0111] Ionic substances IC-2 to IC-9 were prepared in the same manner as in Preparation Example 1, except that the cationic chlorides and anionic sodium compounds of IC-2 to IC-9 in Table 1 below were used instead of the cationic chlorides and anionic sodium compounds used in Preparation Example 1. The obtained ionic substances were subjected to NMR measurement, and the results are shown in Table 1.

[0112] [Table 1]

[0113]

[0114] [Example 1 to Example 17]

[0115] The carbon dioxide absorbing compositions of Examples 1 to 17 including the ionic substances of Preparation Examples 1 to 9 and solvents were prepared according to the compositions of Table 2 below.

[0116] The carbon dioxide absorbing compositions of Examples 1 to 17 were prepared by adding the ionic substance and the solvent in % by weight regardless of the order of addition and mixing at 20 to 40° C. for 5 to 60 minutes.

[0117] [Table 2]

[0118]

[0119] [Comparative Example 1] Preparation of Carbon Dioxide Absorbing Composition

[0120] A carbon dioxide absorbing composition of Comparative Example 1 including an amine and a solvent was prepared according to the composition of Table 3 below.

[0121] Regardless of the order of addition, the amine and the solvent were added in a weight ratio and mixed at 20-40° C. for 5-60 minutes to prepare the carbon dioxide absorbing composition of Comparative Example 1.

[0122] [Table 3]

[0123]

[0124] [Experimental Example 1] Evaluation of carbon dioxide absorption performance

[0125] In order to evaluate the carbon dioxide absorption performance of the carbon dioxide absorption composition according to Examples 1 to 9 and Comparative Example 1, the carbon dioxide absorption performance was measured using a vapor liquid equilibrium (VLE) device manufactured according to a reference (Applied Chemistry for Engineering, 2010, 21 (3), 284-290). The vapor liquid equilibrium device uses a device including a carbon dioxide storage cylinder (150 mL), a constant temperature water tank, a stainless steel reactor (73 mL) equipped with a thermometer, an electronic pressure measuring instrument, and a stirrer. At this time, a constant temperature water tank and a heating block are used to keep the cylinder and the reactor at a constant temperature of 40° C., and the absorption capacity is measured. The measurement error range of the reactor is ± 0.1° C. and ± 0.01 bar.

[0126] The evaluation of carbon dioxide absorption performance is specifically carried out by the following method. First, the interior of the carbon dioxide storage cylinder and the absorption reactor is fully replaced with nitrogen, and then the carbon dioxide is filled in the carbon dioxide storage cylinder and maintained at 1 bar and 40°C. Next, the carbon dioxide absorption composition (6.0g) of Example 1 to Example 9 and Comparative Example 1 is added to the interior of the reactor and maintained at 40°C, then the valve connecting the cylinder and the reactor is opened, and the pressure is measured after reaching absorption equilibrium. The equilibrium pressure is measured in units of 30 minutes, and the above process is repeated and continued until there is no pressure change between the cylinder and the reactor.

[0127] The number of moles of carbon dioxide absorbed according to the pressure change was calculated using the ideal gas equation. The carbon dioxide absorption equivalent calculated according to the following Formula 1 using the number of moles of carbon dioxide absorbed was analyzed and shown in Table 4 below.

[0128] [Formula 1]

[0129] Carbon dioxide absorption equivalent = (number of moles of carbon dioxide absorbed) / (number of moles of ionic species in the absorption composition)

[0130] [Table 4]

[0131]

[0132] [Experimental Example 2] Evaluation of thermal stability

[0133] In order to evaluate the thermal stability of the carbon dioxide absorbing composition according to Examples 10 to 17 and Comparative Example 1, the absorbing composition was bubbled with carbon dioxide at a rate of 100 milliliters (cc) / minute for more than 30 minutes to fully absorb carbon dioxide. 10.0 g of the composition attached with carbon dioxide was placed in a stainless steel container (50 mL) and stored in an oven maintained at a constant temperature of 130° C. for 4.5 days for heat treatment, and the reduction rate of the carbon dioxide absorbing composition calculated by the following formula 2 is shown in the following Table 5.

[0134] [Formula 2]

[0135] Reduction rate of carbon dioxide absorbing composition = 100 - {(number of moles of ionic substances after heat treatment) / (number of moles of ionic substances before heat treatment)} × 100

[0136] [Table 5]

[0137]

[0138] As shown in Table 4, the carbon dioxide absorption equivalents of the Examples were all 0.7 or more, and it was found that the Examples showed improved carbon dioxide absorption performance compared with the Comparative Examples.

[0139] In addition, as shown in Table 5, the reduction rate of ion substances in the examples is 4.0% or less, which shows that the examples have excellent stability in high temperature and alkaline environments. On the other hand, the comparative examples in which monoethanolamine, which is widely used as an amine-based carbon dioxide absorption composition, is introduced show a higher reduction rate than the examples, and it can be seen from the above results that the examples of the present invention show significantly improved stability in the carbon dioxide absorption process.

[0140] The carbon dioxide absorbing composition comprising the ionic substance containing spiroammonium cations and phenoxide-based anions or imidazolium-based anions according to the present invention has improved stability in high temperature and alkaline environments, thereby improving the problems of desorption and limited recycling occurring in the existing carbon dioxide absorbing composition introducing monoethanolamine, and thus the process is very easy to apply to large-scale production.

[0141] Furthermore, the method of separating carbon dioxide using the carbon dioxide absorbing composition is very effective in desorption of carbon dioxide, as compared with an amine-based carbon dioxide absorbing composition, and the carbon dioxide absorbing composition can be reused, thus being a very economical method.

[0142] As described above, the present invention has been described through specific contents and limited embodiments and comparative examples, but this is only provided to help to have a more comprehensive understanding of the present invention. The present invention is not limited to the above embodiments, and technicians in the field of the present invention can make various modifications and variations based on these records.

[0143] Therefore, the concept of the present invention should not be limited to the illustrated embodiments, and all contents of the claims of the present invention and equivalents to the claims or equivalent modifications belong to the scope of the concept of the present invention.

Claims

1. A carbon dioxide absorbing composition comprising an ionic substance, wherein the ionic substance comprises a spiroammonium cation represented by the following chemical formula 1, [Chemical formula 1] In the chemical formula 1, L1 and L2 are each independently a single bond, -O-, -NR 13 -、 or (C1-C8)alkylene, L3 is a single bond, -O-, or -NR 14 - or (C1-C8) alkylene, R1 to R 14 Each is independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, (C3-C20)cycloalkyl or (C2-C20)heterocycloalkyl.

2. The carbon dioxide absorbing composition according to claim 1, wherein The spiroammonium cation is represented by the following chemical formula 2, [Chemical formula 2] In the chemical formula 2, L2 and L3 are each independently a single bond, -O-, -NR 13 - or (C1-C5) alkylene, The R1 to R 14 is hydrogen or (C1-C10) alkyl.

3. The carbon dioxide absorbing composition according to claim 1, wherein The spiroammonium cation is selected from the following chemical formula: 。 4. The carbon dioxide absorbing composition according to any one of claims 1 to 3, wherein The ionic substance includes a phenoxide-based anion represented by the following Chemical Formula 3 or an imidazolate-based anion represented by the following Chemical Formula 4, [Chemical formula 3] In the chemical formula 3, R 21 To R 25 are independently hydrogen, amino, hydroxy, nitro, amide, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, The amino, hydroxyl, amide, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylamino, dialkylamino, alkylaminoalkyl and dialkylaminoalkyl are optionally substituted with one or more substituents selected from halogen, cyano, amino, nitro, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl and C1-C10 alkoxycarbonyl, [Chemical formula 4] In the chemical formula 4, A1 to A4 are each independently CR or N, At least one of A1 to A4 is N, R is hydrogen, amino, C1-C10 alkyl, C1-C10 alkoxy, C1-C10 alkylcarbonyl, C1-C10 alkoxycarbonyl, C1-C10 alkylamino, di-C1-C10 alkylamino, C1-C10 alkylcarbonylamino, C1-C10 alkylaminoC1-C10 alkyl or di-C1-C10 alkylaminoC1-C10 alkyl, or two or more R are connected to form a ring.

5. The carbon dioxide absorbing composition according to claim 1, wherein The carbon dioxide absorbing composition comprises water.

6. The carbon dioxide absorbing composition according to claim 5, wherein The carbon dioxide absorbing composition further comprises one or more solvents other than water.

7. The carbon dioxide absorbing composition according to claim 1, wherein The carbon dioxide absorption equivalent of the carbon dioxide absorbing composition represented by the following formula 1 is 0.6 or more, [Formula 1] Carbon dioxide absorption equivalent = (number of moles of carbon dioxide absorbed) / (number of moles of ionic species in the absorbent composition).

8. The carbon dioxide absorbing composition according to claim 1, wherein The carbon dioxide absorbing composition further comprises one or more amine absorbents.

9. A method for separating carbon dioxide, comprising: In a first step, the carbon dioxide absorbing composition according to claim 1 is contacted with a mixture containing carbon dioxide; as well as In the second step, the carbon dioxide absorbing composition is subjected to a heat treatment to desorb the carbon dioxide attached to the absorbing composition.

10. The method for separating carbon dioxide according to claim 9, wherein: The first step and the second step are set as a unit process, and the unit process is repeated two or more times to continuously separate carbon dioxide.

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