Method for preparing and separating alkylene carbonate using carbon dioxide in air

Abstract

Disclosed is a method for preparing and separating alkylene carbonate using carbon dioxide in the air. The method comprises the steps of: injecting air containing carbon dioxide into an amine solution containing a diamine compound to obtain a carbon dioxide-captured solution; adding an alkylene oxide, a catalyst, and a solvent to the carbon dioxide-captured solution and reacting the additives to obtain a solution in which an alkylene carbonate has been produced; and separating the alkylene carbonate from the solution in which the alkylene carbonate has been produced.

Description

Method for producing and separating alkylene carbonate using carbon dioxide in the air

[0001] Cross-reference to related applications

[0002] This application claims priority to Republic of Korea Patent Application No. 10-2024-0088737, filed July 5, 2024, the entire contents of which are incorporated herein by reference.

[0003] Description of Nationally Supported Research and Development

[0004] This study was conducted at the Korea Institute of Science and Technology (KIST) under the management of the National Research Foundation of Korea (NRF) under the Ministry of Science and ICT. The research project name is DACU Core Technology Development (R&D), and the research project name is Development of Core Technology for Simultaneous Capture and Conversion of Carbon Dioxide from Air (Project Unique Number: 1711197843, Project Number: 00259920).

[0005] The present disclosure discloses a method for producing and separating alkylene carbonates using carbon dioxide in the air.

[0006] Organic carbonates, including ethylene carbonate, are widely used in the chemical and materials industries, including as electrolyte solvents for secondary batteries. The global ethylene carbonate market reached approximately $450 million in 2021 and is showing a steep upward trend each year. Notably, it is projected to reach $1.35 billion by 2030, approximately three times the 2021 figure. Demand for ethylene carbonate is growing significantly with the growth of the secondary battery industry, with hundreds of thousands of tons produced domestically annually. However, technology for producing alkylene carbonates using atmospheric carbon dioxide as a raw material, which could significantly contribute to mitigating global warming, is still lacking.

[0007] Traditionally, alkylene carbonates have been manufactured using high-concentration carbon dioxide. This high-concentration carbon dioxide has been obtained by separating carbon dioxide from flue gases emitted from power plants. Flue gases typically contain 10% to 15% carbon dioxide. To separate and concentrate this carbon dioxide to a high concentration, an absorption-stripping process using a carbon dioxide absorbent, such as an amine solution, is required. In this entire carbon dioxide capture system, 80% of the energy consumed occurs during the stripping process. Therefore, there is a need for technological development for a method that can directly manufacture alkylene carbonates using a solution containing captured carbon dioxide without stripping, and for a method that can manufacture alkylene carbonates with less energy.

[0008] In one aspect, the present disclosure aims to provide a method for producing and separating alkylene carbonate from carbon dioxide in the air.

[0009] In one aspect, the present disclosure provides a method for producing and separating an alkylene carbonate using carbon dioxide in the air, the method comprising the steps of: injecting air containing carbon dioxide into a solution containing a carbon dioxide capture agent to obtain a solution in which carbon dioxide is captured; adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which carbon dioxide is captured and reacting the same to obtain a solution in which an alkylene carbonate is produced; and separating an alkylene carbonate from the solution in which the alkylene carbonate is produced.

[0010] In an exemplary embodiment, the carbon dioxide capture agent may be a diamine compound represented by the following chemical formula 1.

[0011] [Chemical Formula 1]

[0012]

[0013] In the above formula,

[0014] n is any integer selected from 1 to 3,

[0015] R 1 and R 2 are identical to each other and are a hexylamine group, a methyl group, an ethyl group, a propyl group or a butyl group,

[0016] R 3 is a methyl group.

[0017] In an exemplary embodiment, the solution including the carbon dioxide capture agent may be one in which the carbon dioxide capture agent is dissolved in one or more solvents selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

[0018] In an exemplary embodiment, the solution comprising the carbon dioxide capture agent may have a boiling point of 160 to 300° C.

[0019] In an exemplary embodiment, the catalyst for producing the alkylene carbonate may be a quaternary ammonium halide.

[0020] In an exemplary embodiment, the quaternary ammonium halide may include at least one selected from the group consisting of cetyltrimethylammonium bromide (CTAB), tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC1), and tetra-n-butylammonium iodide (TBAI).

[0021] In an exemplary embodiment, the solvent may be at least one selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

[0022] In an exemplary embodiment, the step of obtaining a solution in which the alkylene carbonate is produced may include adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which the carbon dioxide is captured, and reacting the solution at 80 to 160° C. under an inert gas atmosphere.

[0023] In an exemplary embodiment, the inert gas may include at least one selected from the group consisting of hydrogen, nitrogen, helium, argon, and neon.

[0024] In an exemplary embodiment, the inert gas atmosphere may be one in which the reactor pressure is adjusted to 6 to 12 bar by injecting an inert gas.

[0025] In an exemplary embodiment, the reaction may be carried out for 2 to 12 hours.

[0026] In an exemplary embodiment, the step of separating the alkylene carbonate may include injecting air containing carbon dioxide into a solution in which the alkylene carbonate is produced to obtain a separated solvent layer and a gel layer, wherein the solvent layer may include the solvent and the alkylene carbonate, and the gel layer may include the carbon dioxide capture agent, carbon dioxide, and a catalyst.

[0027] In an exemplary embodiment, the solvent layer and the gel layer may be obtained by decantation.

[0028] In an exemplary embodiment, the method may further include a step of adding an alkylene oxide and a solvent to the obtained gel layer and reacting them to obtain a solution in which an alkylene carbonate is produced.

[0029] In an exemplary embodiment, the alkylene oxide may be represented by the following chemical formula 2, and the alkylene carbonate may be represented by the following chemical formula 3.

[0030] [Chemical Formula 2]

[0031]

[0032] [Chemical Formula 3]

[0033]

[0034] In the above chemical formulas 2 and 3, R1 and R2 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted hydroxyalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, or a substituted or unsubstituted arylalkyl group having 7 to 13 carbon atoms.

[0035] In one aspect, the technology disclosed in the present disclosure provides a method for producing and separating alkylene carbonates from carbon dioxide in the air. The method directly produces alkylene carbonates using a solution containing captured carbon dioxide without stripping, and utilizes carbon dioxide in the air rather than exhaust gas, thereby reducing the concentration of carbon dioxide in the atmosphere, which contributes to global warming.

[0036] In another aspect, the technology disclosed in the present disclosure has the effect of providing a method for easily separating and purifying the alkylene carbonate by producing an alkylene carbonate using carbon dioxide in the air and then injecting carbon dioxide in the air again to cause layer separation.

[0037] In another aspect, the technology disclosed in the present disclosure enables continuous production of alkylene carbonates by reusing the carbon dioxide capture agent and catalyst obtained by layer separation, and has the effect of enabling a recycling reaction.

[0038] Figure 1 shows the structural formula of an aliphatic quaternary ammonium bromide catalyst used in one embodiment.

[0039] Figure 2 illustrates a flow chart of a method for producing and separating an alkylene carbonate according to one embodiment. When carbon dioxide is re-injected into the solution in which the reaction is completed and the alkylene carbonate is produced, phase separation occurs into a solvent layer and an amine gel layer containing carbon dioxide. The solvent layer and the amine gel layer can be separated by decantation. Furthermore, by adding an alkylene oxide and a solvent to the separated amine gel layer, the alkylene carbonate can be produced again, thereby enabling a recycling reaction.

[0040] Figure 3 shows step-by-step photographs of a method for producing and separating an alkylene carbonate according to one embodiment.

[0041] Figure 4 is a reaction product of a compound of chemical formula 1-1 and propylene oxide (PO) according to a comparative example. 1 H NMR spectra are shown. (A) is the spectrum of tetrabutylammonium bromide (TBAB), (B) is the compound of chemical formula 1-1, (C) is the spectrum of the product obtained by reacting the compound of chemical formula 1-1 with propylene oxide without CO2 capture, and (D) is the spectrum of the product obtained by reacting the compound of chemical formula 1-1 with propylene oxide after CO2 capture (PC (▼), TBAB (●)).

[0042] Figure 5 is a graph showing the reaction product of t-BAE and propylene oxide (PO) according to a comparative example. 1 H NMR spectra are shown. (A) is the spectrum of tetrabutylammonium bromide (TBAB), (B) is the spectrum of 2-(tert-Butylamino)ethanol (t-BAE), and (C) is the spectrum of the product of the reaction of t-BAE and propylene oxide without CO2 capture (TBAB (●), t-BAE (*), t-BAE+PO reaction product (▼)).

[0043] Hereinafter, the present disclosure is described in detail.

[0044] In one aspect, the present disclosure provides a method for producing and separating an alkylene carbonate using carbon dioxide in the air, the method comprising the steps of: injecting air containing carbon dioxide into a solution containing a carbon dioxide capture agent to obtain a solution in which carbon dioxide is captured; adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which carbon dioxide is captured and reacting the same to obtain a solution in which an alkylene carbonate is produced; and separating an alkylene carbonate from the solution in which the alkylene carbonate is produced.

[0045] The present disclosure provides a method for directly synthesizing an alkylene carbonate by adding an alkylene oxide to a solution containing carbon dioxide captured from the air. As shown in the following reaction scheme 1, carbon dioxide and an alkylene oxide react in the presence of a catalyst to synthesize an alkylene carbonate.

[0046] [Reaction Formula 1]

[0047]

[0048] The carbon dioxide capture process according to the present disclosure must be water-free. If water is present in the capture solution, it reacts with the alkylene oxide to produce a glycol compound, as shown in Reaction Scheme 2 below. Therefore, a water-free carbon dioxide capture system is required. Therefore, tertiary amines, which can chemically capture carbon dioxide only in the presence of water, are not suitable for the carbon dioxide capture process according to the present disclosure.

[0049] [Reaction Formula 2]

[0050]

[0051] In addition, representative CO2 capturing amines such as monoethanolamine, diethanolamine, and aminomethylpropanol react with alkylene oxides to produce alcohol compounds as shown in the following reaction scheme 3, and are therefore not suitable for the carbon dioxide capturing process according to the present disclosure.

[0052] [Reaction Formula 3]

[0053]

[0054] In addition, amines that react with alkylene oxides are not suitable for the carbon dioxide capture process according to the present disclosure because a ring opening reaction occurs by the amine as shown in the following reaction scheme 4.

[0055] [Reaction Formula 4]

[0056]

[0057] Therefore, in the carbon dioxide capture process according to the present disclosure, it may be preferable that the carbon dioxide capture agent be a diamine compound containing an ether group.

[0058] In an exemplary embodiment, the carbon dioxide capture agent may be a diamine compound represented by the following chemical formula 1.

[0059] [Chemical Formula 1]

[0060]

[0061] In the above formula,

[0062] n is any integer selected from 1 to 3,

[0063] R 1 and R 2 are identical to each other and are a hexylamine group, a methyl group, an ethyl group, a propyl group or a butyl group,

[0064] R 3 is a methyl group.

[0065] In a method for producing and separating alkylene carbonates using carbon dioxide in the air according to the present disclosure, the carbon dioxide capture agent is capable of capturing not only high-concentration carbon dioxide but also low-concentration carbon dioxide of about 450 ppm in the air. The carbon dioxide capture agent is capable of capturing low-concentration carbon dioxide and dissociating with the carbon dioxide. Therefore, separation from products generated in a subsequent process is possible, thereby providing the effect of producing and separating alkylene carbonates from carbon dioxide in the air.

[0066] In an exemplary embodiment, the carbon dioxide capture agent may be a diamine compound represented by the following chemical formula 1-1, 1-2 or 1-3.

[0067] [Chemical Formula 1-1]

[0068]

[0069] [Chemical Formula 1-2]

[0070]

[0071] [Chemical Formula 1-3]

[0072]

[0073] In an exemplary embodiment, the solution including the carbon dioxide capture agent may be one in which the carbon dioxide capture agent is dissolved in one or more solvents selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

[0074] In an exemplary embodiment, the solution including the carbon dioxide capture agent may have a boiling point of 160 to 300°C. Accordingly, the boiling point of the solution is lowered to below 160°C, thereby preventing the possibility of carbon dioxide being lost along with air during the process of capturing carbon dioxide, and the boiling point of the solution is higher than 300°C, thereby preventing the problem of the viscosity of the solution increasing, thereby slowing down the CO2 capture rate too much.

[0075] In an exemplary embodiment, the catalyst for producing the alkylene carbonate may be a quaternary ammonium halide. Accordingly, when layer separation is formed after the reaction, the catalyst is present in the amine gel layer, resulting in the pure separation of the alkylene oxide product contained in the solvent layer, and the carbon dioxide capture agent and the amine gel layer containing the catalyst can be recycled.

[0076] In an exemplary embodiment, the quaternary ammonium halide may be an aliphatic quaternary ammonium halide.

[0077] In an exemplary embodiment, the quaternary ammonium halide may be an aliphatic quaternary ammonium halide having 2 to 4 carbon atoms.

[0078] In an exemplary embodiment, the quaternary ammonium halide may be an aliphatic quaternary ammonium bromide, chloride or iodide.

[0079] In an exemplary embodiment, the quaternary ammonium halide may include at least one selected from the group consisting of cetyltrimethylammonium bromide (CTAB), tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC1), and tetra-n-butylammonium iodide (TBAI).

[0080] In an exemplary embodiment, the quaternary ammonium halide may be tetraethylammonium bromide (TEAB).

[0081] In general, there has been a problem in that amines have high boiling points and the produced alkylene carbonates also have high boiling points, making separation after the reaction difficult (e.g., ethylene carbonate 243°C, propylene carbonate 242°C). The method according to the present disclosure uses a solvent together with a catalyst for producing alkylene carbonates to facilitate the separation of alkylene carbonates.

[0082] In an exemplary embodiment, the solvent added to the solution containing the carbon dioxide captured together with the catalyst for producing alkylene oxide and alkylene carbonate may be the same as or different from the solvent used in the solution containing the carbon dioxide capture agent.

[0083] In an exemplary embodiment, the solvent added to the solution in which the carbon dioxide is captured together with the catalyst for producing alkylene oxide and alkylene carbonate may be at least one selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

[0084] In an exemplary embodiment, the solvent added to the carbon dioxide-captured solution together with the catalyst for producing alkylene oxide and alkylene carbonate may be diglyme (diethylene glycol dimethyl ether).

[0085] In an exemplary embodiment, the step of obtaining a solution in which the alkylene carbonate is produced may include adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which the carbon dioxide is captured, and reacting the mixture at 80 to 160° C., 80 to 140° C., 80 to 120° C., or 80 to 100° C. under an inert gas atmosphere. The method for producing and separating an alkylene carbonate according to the present disclosure provides the effect of producing an alkylene carbonate by adding an alkylene oxide, a catalyst, and a solvent in a state in which carbon dioxide in the air is dissolved in an amine solution without a carbon dioxide concentration process that consumes a large amount of energy, and then easily separating and purifying the alkylene carbonate through layer separation by injecting carbon dioxide in the air again.

[0086] In an exemplary embodiment, the inert gas may include at least one selected from the group consisting of hydrogen, nitrogen, helium, argon, and neon.

[0087] In an exemplary embodiment, the inert gas atmosphere may be one in which the reactor pressure is adjusted to 6 to 12 bar by injecting an inert gas.

[0088] In an exemplary embodiment, the reaction may be carried out for 2 to 12 hours, 2 to 10 hours, or 4 to 10 hours.

[0089] In an exemplary embodiment, the step of separating the alkylene carbonate may include injecting air containing carbon dioxide into a solution in which the alkylene carbonate is produced to obtain a separated solvent layer and a gel layer, wherein the solvent layer may include the solvent and the alkylene carbonate, and the gel layer may include the carbon dioxide capture agent, carbon dioxide, and a catalyst. The method for producing and separating an alkylene carbonate according to the present disclosure separates the alkylene carbonate through phase inversion and layer separation by re-injecting carbon dioxide in the air after producing the alkylene carbonate from carbon dioxide in the air. The method provides the effect of producing the alkylene carbonate with high efficiency using carbon dioxide in the air rather than exhaust gas, and then easily separating and purifying the alkylene carbonate through phase inversion and layer separation.

[0090] In an exemplary embodiment, the solvent layer and the gel layer may be obtained by decantation.

[0091] In an exemplary embodiment, the method may further include a step of adding an alkylene oxide and a solvent to the obtained gel layer and reacting them to obtain a solution in which an alkylene carbonate is produced. Thereafter, carbon dioxide in the air may be re-injected as in the subsequent process described above to separate and purify the alkylene carbonate through layer separation. In the method according to the present disclosure, the carbon dioxide capture agent, which is a diamine compound containing an ether group, captures carbon dioxide in the air well and can be separated from the reaction product and reused. The present disclosure has the effect of enabling a recycling reaction by reusing the carbon dioxide capture agent and the catalyst.

[0092] In an exemplary embodiment, the alkylene oxide may be represented by the following chemical formula 2, and the alkylene carbonate may be represented by the following chemical formula 3.

[0093] [Chemical Formula 2]

[0094]

[0095] [Chemical Formula 3]

[0096]

[0097] In the above chemical formulas 2 and 3, R1 and R2 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted hydroxyalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, or a substituted or unsubstituted arylalkyl group having 7 to 13 carbon atoms.

[0098] In an exemplary embodiment, R1 and R2 in the above chemical formulas 2 and 3 may be connected to each other to form a ring or may not form a ring.

[0099] In an exemplary embodiment, the substitution may be with an ether group.

[0100] In an exemplary embodiment, the alkylene oxide may be ethylene oxide, propylene oxide or butylene oxide.

[0101] In an exemplary embodiment, the alkylene carbonate may be ethylene carbonate, propylene carbonate or butylene carbonate.

[0102] Hereinafter, the present disclosure will be described in more detail through examples. These examples are intended solely to illustrate the present disclosure, and it will be apparent to those skilled in the art that the scope of the present disclosure is not limited by these examples.

[0103] Example 1.

[0104] A diamine compound (1.2 g, 6.3 mmol) of the following chemical formula 1-1 was dissolved in 15 mL of a diglyme solvent as a carbon dioxide capture agent, and then treated with air containing 430 ppm of carbon dioxide at 500 cc / min to obtain an amine solution with carbon dioxide captured. The amount of carbon dioxide captured over time is shown in Table 1 below.

[0105] [Chemical Formula 1-1]

[0106]

[0107] Time CO2 Capture (CO2mol / amine mol) 40.126 0.32 12 0.74 24 1.03

[0108] Example 2.

[0109] In the above Example 1, propylene oxide (4.5 g, 77.5 mmol) as an alkylene oxide, an aliphatic quaternary ammonium bromide catalyst (0.5 mmol) listed in Table 2 below, and 15 g of diglyme solvent were added to the amine solution in which carbon dioxide was captured by treating for 24 hours, and the mixture was reacted at 80° C. for 4 hours under a nitrogen atmosphere of 10 bar to obtain a solution in which propylene carbonate (PC) was produced.

[0110] Afterwards, air containing carbon dioxide was injected again into the solution in which the propylene carbonate was produced for 24 hours, and the solution in which layers were separated into a solvent layer and a gel layer was decanted. Through the layer separation, a solvent layer containing the solvent and propylene carbonate and a gel layer containing the carbon dioxide capture agent, carbon dioxide, and a catalyst were obtained. 1 H NMR analysis (400 MHz, Brucker) was performed.

[0111] As a result, it was found that there were differences in the amount of propylene carbonate produced and the results of layer separation depending on the type of catalyst used (see Table 2). TMAB and TEAB, which have short alkyl group lengths, showed no or low reactivity, while when CTAB, TPAB, or TBAB were used as catalysts, propylene carbonate was detected in the diglyme layer, confirming excellent PC conversion reactivity.

[0112] Propylene carbonate (PC) yield (%) = 100 × amount of PC produced (mmol) / amount of CO2 captured (mmol)

[0113] Catalyst PC yield (%)NH4Br20TMAB0CTAB76TEAB17TPAB100TBAB100

[0114] Example 3.

[0115] In the same manner as in Example 2, alkylene carbonate was prepared and separated from carbon dioxide in the air, but a diamine compound of chemical formula 1-2 or 1-3 was used as a carbon dioxide capture agent to obtain an amine solution in which carbon dioxide was captured, and tetrabutylammonium bromide (TBAB) was used as a catalyst. After treating air containing 430 ppm of carbon dioxide at 500 cc / min for 24 hours, the amount of carbon dioxide captured and the yield of propylene carbonate as a result of the reaction are shown in Table 3 below.

[0116] Carbon dioxide capture agent CO2 capture amount (CO2 mol / amine mol) PC yield (%) [Chemical formula 1-2] 1.0292 [Chemical Formula 1-3] 1.0495

[0117] Example 4.

[0118] In the same manner as in Example 2, alkylene carbonate was prepared and separated from carbon dioxide in the air, but tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC1), or tetra-n-butylammonium iodide (TBAI) was used as a catalyst, and triglyme or tetraglyme was used as a solvent, thereby obtaining an amine solution containing carbon dioxide and a solution containing propylene carbonate. The results of the reaction by changing the catalyst and solvent as described above are shown in Table 4 below.

[0119] Catalyst solvent PC yield (%) TBAB triglyme 93 TBACl tetraglyme 86 TBAI tetraglyme 100

[0120] Example 5.

[0121] In the same manner as in Example 2, alkylene carbonate was produced and separated from carbon dioxide in the air, but tetrabutylammonium bromide (TBAB) was used as a catalyst, and the solvents in Table 5 below were used as solvents to obtain an amine solution containing carbon dioxide and a solution containing propylene carbonate. The yield of propylene carbonate as a result of the reaction is shown in Table 5 below.

[0122] Solvent Solvent Structure PC Yield (%) Monoglyme 96 Tetraglyme 94 propylene carbonate 921,4-dioxane 89THF 942-methyltetrahydrofuran 96

[0123] Example 6.

[0124] In the same manner as in Example 2, an alkylene carbonate was prepared and separated from carbon dioxide in the air, but tetrabutylammonium bromide (TBAB) was used as a catalyst, and the compounds in Table 6 below were used as alkylene oxides to prepare the alkylene carbonate. The reaction temperature and reaction time are as shown in Table 6 below, and the yield of the alkylene carbonate produced as a result of the reaction is shown in Table 6 below.

[0125] Yield of alkylene carbonate produced (%) = 100 × Amount of alkylene carbonate produced (mmol) / Amount of CO2 captured (mmol)

[0126] Alkylene oxide reaction temperature and reaction time produced alkylene carbonate produced alkylene carbonate yield (%) 80 ℃, 4 h 100 80 ℃, 4 h 95 80 ℃, 9 h 90 80 ℃, 9 h 92 80 ℃, 9 h 99 80 ℃, 9 h 96 100 ℃, 9 h 91 100 ℃, 9 h 88

[0127] Example 7.

[0128] In the same manner as in Example 2, alkylene carbonate was prepared and separated from carbon dioxide in the air, but tetraethylammonium bromide (TEAB) was used as a catalyst, and propylene oxide, a catalyst, and a solvent were added to cause the reaction. The reaction temperature was raised to 120°C to convert the alkylene carbonate into propylene carbonate (see Figs. 2 and 3). The yield of propylene carbonate as a result of the reaction is shown in Table 7 below.

[0129] By adding propylene oxide, catalyst, and solvent and increasing the reaction temperature, the conversion reaction to propylene carbonate was performed, and it was confirmed that the PC conversion reactivity was excellent even when TEAB with a short alkyl group length was used as a catalyst. Specifically, when TEAB was used as a catalyst, propylene carbonate was produced at a yield of 17% based on the captured CO2 when the PC conversion reaction was performed at 80°C, but when the reaction temperature was increased to 120°C, the propylene carbonate yield increased by nearly four times.

[0130] After the conversion reaction to propylene carbonate, a white solid was observed in the solution where propylene carbonate was produced, which was expected to be TEAB. In addition, when CO2 was injected again into the solution where propylene carbonate was produced, it was confirmed that phase separation occurred into two layers. The reaction product existing as a single phase was phase separated by CO2 injection, allowing the separation of the carbon dioxide capture agent, propylene carbonate, and catalyst. The layers were separated into a solvent layer containing diglyme and propylene carbonate and an amine gel layer containing the carbon dioxide capture agent and catalyst. NMR analysis showed that approximately 95% of the total amount of propylene carbonate produced was confirmed in the solvent layer. The catalyst TEAB was confirmed in the amine gel layer where carbon dioxide was captured, and was not detected in the solvent layer, i.e., the diglyme layer. Therefore, propylene oxide and diglyme were added again to the separated amine gel layer to synthesize propylene carbonate, confirming that the recycling reaction was possible. As a result of reusing the carbon dioxide capture agent and catalyst as described above, it was confirmed that propylene carbonate could be produced in a high yield even in the second, third, and fourth reactions, as shown in Table 7 below.

[0131] Reaction order catalyst PC yield (%) 1st TEAB 69 2nd TEAB 75 3rd TEAB 72 4th TEAB 72

[0132] Comparative Example 1.

[0133] After reacting the compound of chemical formula 1-1 with propylene oxide in the presence of the catalyst TBAB at 80°C for 4 hours, 1 As a result of measuring H-NMR, only the compound of chemical formula 1-1 and the catalyst TBAB were detected, as shown in (C) of Fig. 4, confirming that propylene carbonate was not produced. On the other hand, when CO2 was captured using the compound of chemical formula 1-1 and reacted under the same conditions, it was confirmed that propylene carbonate (PC) was produced, as shown in (D) of Fig. 4.

[0134] [Chemical Formula 1-1]

[0135]

[0136] Comparative Example 2.

[0137] After reacting 2-(tert-Butylamino)ethanol (t-BAE), which contains an alcohol group other than the compound of chemical formula 1-1, as a carbon dioxide capture agent, in the presence of propylene oxide (PO) and the catalyst TBAB at 80°C for 4 hours, 1 H-NMR measurements confirmed that the alcohol group of t-BAE reacts with PO to produce various substances (see Fig. 5). Accordingly, it was confirmed that a carbon dioxide capture agent capable of reacting with alkylene oxide is not suitable for the method of preparing and separating alkylene carbonates of the present disclosure.

[0138] While specific aspects of the present disclosure have been described in detail, it will be apparent to those skilled in the art that these specific descriptions are merely preferred embodiments and do not limit the scope of the present disclosure. Accordingly, the substantial scope of the present disclosure is defined by the appended claims and their equivalents.

Claims

1. A step of injecting air containing carbon dioxide into a solution containing a carbon dioxide capture agent to obtain a solution containing carbon dioxide captured; A step of adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which the carbon dioxide is captured and reacting to obtain a solution in which an alkylene carbonate is produced; and A method for producing and separating an alkylene carbonate using carbon dioxide in the air, comprising a step of separating an alkylene carbonate from a solution in which the alkylene carbonate is produced.

2. In paragraph 1, The above carbon dioxide capture agent is a diamine compound represented by the following chemical formula 1, and a method for producing and separating alkylene carbonate using carbon dioxide in the air: [Chemical Formula 1] In the above formula, n is any integer selected from 1 to 3, R 1 and R 2 are identical to each other and are a hexylamine group, a methyl group, an ethyl group, a propyl group or a butyl group, R 3 is a methyl group.

3. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the solution containing the carbon dioxide capture agent is a solution in which the carbon dioxide capture agent is dissolved in at least one solvent selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

4. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the solution containing the carbon dioxide capture agent has a boiling point of 160 to 300°C.

5. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the catalyst for producing the above alkylene carbonate is a quaternary ammonium halide.

6. In paragraph 5, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the quaternary ammonium halide comprises at least one selected from the group consisting of cetyltrimethylammonium bromide (CTAB), tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC1), and tetra-n-butylammonium iodide (TBAI).

7. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the solvent is at least one selected from the group consisting of monoglyme, diglyme, triglyme, tetraglyme, propylene carbonate, 1,4-dioxane, THF, and 2-methyltetrahydrofuran.

8. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the step of obtaining a solution in which the above-mentioned alkylene carbonate is produced comprises adding an alkylene oxide, a catalyst for producing an alkylene carbonate, and a solvent to the solution in which the carbon dioxide is captured, and reacting the solution at 80 to 160°C under an inert gas atmosphere.

9. In paragraph 8, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the inert gas comprises at least one selected from the group consisting of hydrogen, nitrogen, helium, argon, and neon.

10. In paragraph 8, A method for producing and separating alkylene carbonate using carbon dioxide in the air, wherein the above inert gas atmosphere is obtained by injecting an inert gas and adjusting the reactor pressure to 6 to 12 bar.

11. In paragraph 8, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the above reaction is carried out for 2 to 12 hours.

12. In paragraph 1, The step of separating the above alkylene carbonate is to obtain a separated solvent layer and a gel layer by injecting air containing carbon dioxide into the solution in which the above alkylene carbonate is produced, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the solvent layer comprises the solvent and an alkylene carbonate, and the gel layer comprises the carbon dioxide capture agent, carbon dioxide, and a catalyst.

13. In paragraph 12, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the solvent layer and the gel layer are obtained by decantation.

14. In paragraph 12, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the method further comprises a step of adding an alkylene oxide and a solvent to the obtained gel layer and reacting them to obtain a solution in which an alkylene carbonate is produced.

15. In paragraph 1, A method for producing and separating an alkylene carbonate using carbon dioxide in the air, wherein the alkylene oxide is represented by the following chemical formula 2 and the alkylene carbonate is represented by the following chemical formula 3: [Chemical Formula 2] [Chemical Formula 3] In the above chemical formulas 2 and 3, R1 and R2 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted hydroxyalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, or a substituted or unsubstituted arylalkyl group having 7 to 13 carbon atoms.

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