A method for capturing carbon dioxide using a ternary solvent system based on superbase ionic liquids

Abstract

The present invention discloses a method for capturing carbon dioxide using a ternary solvent system based on a superbase ionic liquid. The ternary solvent system consists of a superbase ionic liquid, a phenolic organic compound, and an alcoholic organic compound; the molar ratio of the superbase ionic liquid to the phenolic organic compound and the alcoholic organic compound is 1:1-6:2-10, respectively. By adjusting the content of each component in the ternary solvent system, the present invention achieves control of the capture capacity and desorption temperature, providing a simple and easy method for regulating the carbon capture behavior of the solvent.

Description

Technical Field

[0001] The present invention belongs to the field of carbon dioxide capture, and in particular relates to a method for capturing carbon dioxide using a ternary solvent system based on a superbase ionic liquid. Background Art

[0002] To date, various carbon capture technologies have been developed. Among them, the most widely used industrially is the carbon capture method based on aqueous alcoholamine solutions. This method offers good carbon capture efficiency and capacity, but it also suffers from drawbacks such as the susceptibility of the absorbent to thermal degradation, equipment corrosion, and high solvent regeneration energy consumption.

[0003] In recent years, superbase ionic liquids have attracted attention in the field of carbon capture due to their simple synthesis process and high carbon capture capacity. However, the high viscosity of superbase ionic liquids makes them unsuitable for large-scale practical application. To address this issue, researchers have mixed superbase ionic liquids with organic solvents to obtain carbon capture solvents with lower viscosity. However, how to control the carbon capture performance (capture capacity, regeneration temperature, etc.) of superbase ionic liquid-organic solvent mixed systems remains a challenge for researchers. Summary of the Invention

[0004] The present invention aims to provide a method for capturing CO2 using a ternary solvent system composed of a superbase ionic liquid and an organic compound. By adjusting the content of the components in the ternary solvent system, the carbon capture performance of the solvent, such as its capture capacity and regeneration temperature, can be controlled.

[0005] The method for capturing CO2 using a ternary solvent system formed by a superbase ionic liquid and an organic matter provided by the present invention comprises the following steps:

[0006] 1) preparing a ternary solvent system, wherein the ternary solvent system consists of a superbase ionic liquid, a phenolic organic compound, and an alcoholic organic compound;

[0007] 2) The carbon dioxide-containing gas is introduced into a container containing the ternary solvent system, and the pressure and temperature are controlled and the gas is captured.

[0008] In step 1) of the above method, the superbase ionic liquid is synthesized by an acid-base reaction between a superbase and a phenolic substance;

[0009] Wherein, the superbase used to synthesize the superbase ionic liquid is selected from at least one of tetramethylguanidine (TMG), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), and specifically 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU);

[0010] The phenolic substance used to synthesize the superbase ionic liquid is selected from the group consisting of phenol, 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-trifluoromethylphenol, 2,4-difluorophenol, 4-fluoro-3-methylphenol, 2-methoxy-4-methylphenol, 2-methoxy-4-propylphenol, 2,6-dimethoxyphenol, thymol, carvacrol, eugenol, and vanillin, and specifically 4-fluorophenol;

[0011] The phenolic substance used to constitute the ternary solvent system is selected from the group consisting of: phenol, 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-trifluoromethylphenol, 2,4-difluorophenol, 4-fluoro-3-methylphenol, 2-methoxy-4-methylphenol, 2-methoxy-4-propylphenol, 2,6-dimethoxyphenol, thymol, carvacrol, eugenol, and vanillin, and specifically 4-fluorophenol;

[0012] The alcohol substance used to constitute the ternary solvent system is selected from at least one of butanol, leaf alcohol, ethylene glycol, butanediol, diethylene glycol, triethylene glycol, and polyethylene glycol, and specifically can be ethylene glycol.

[0013] In step 1), the ternary solvent system is prepared by the following method: mixing a superbase and a phenolic substance in an equal molar ratio, reacting under heating and stirring, and cooling to room temperature to obtain a superbase ionic liquid; mixing the superbase ionic liquid, a phenolic organic substance, and an alcohol organic substance at room temperature and stirring to obtain a ternary solvent system;

[0014] The reaction time may be 1-4 hours, specifically 2 hours;

[0015] The molar ratios of the superbase ionic liquid to the phenolic organic compound and the alcohol organic compound are: 1:1-6:2-10, preferably 1:1-4:2-3, 1:1:2-3, 1:1:2, 1:1:3, 1:2:2, 1:4:2.

[0016] In step 2), the pressure of the CO2 gas is 0.005 to 0.1 MPa, and the capture temperature is 20-70°C, specifically 25°C.

[0017] Weighing is performed during the capture process until the mass of the container no longer changes, i.e., absorption saturation is reached.

[0018] The above method may further include the following operation: after absorption saturation, introducing inert gas into the obtained saturated solution, heating, desorbing CO2 to recover the ternary solvent system.

[0019] Wherein, the flow rate of the inert gas is 40-100 mL / min, specifically 50 mL / min;

[0020] The inert gas may specifically be N2;

[0021] The desorption temperature is 25-80°C, preferably 30-60°C.

[0022] The present invention realizes the regulation of capture capacity and desorption temperature by adjusting the content of each component in the ternary solvent system, and provides a simple and easy method for regulating the carbon capture behavior of the solvent. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0024] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0025] Example 1

[0026] The superbase DBU was added to a glass vial, followed by an equal molar amount of 4-fluorophenol (4-F-PhOH). The reaction was stirred at 50°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain the liquid ionic liquid [DBUH][4-F-PhO]. Subsequently, a certain amount of 4-fluorophenol and ethylene glycol (EG) were added to achieve a molar ratio of 1:1:3 between the ionic liquid, 4-fluorophenol, and EG. The resulting ternary solvent system was designated [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:3).

[0027] Example 2

[0028] The superbase DBU was added to a glass vial, followed by an equal molar amount of 4-fluorophenol (4-F-PhOH). The reaction was stirred at 50°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain the liquid ionic liquid [DBUH][4-F-PhO]. Subsequently, a certain amount of 4-fluorophenol and ethylene glycol (EG) were added to achieve a molar ratio of 1:1:2 between the ionic liquid, 4-fluorophenol, and EG. The resulting ternary solvent system was designated [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:2).

[0029] Example 3

[0030] The superbase DBU was added to a glass vial, followed by an equimolar amount of 4-fluorophenol (4-F-PhOH). The reaction was stirred at 50°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain the liquid ionic liquid [DBUH][4-F-PhO]. Subsequently, a certain amount of 4-fluorophenol and ethylene glycol (EG) were added to achieve a molar ratio of 1:2:2 between the ionic liquid, 4-fluorophenol, and EG. The resulting ternary solvent system was designated [DBUH][4-F-PhO]:4-F-PhOH:EG (1:2:2).

[0031] Example 4

[0032] The superbase DBU was added to a glass vial, followed by an equimolar amount of 4-fluorophenol (4-F-PhOH). The reaction was stirred at 50°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain the liquid ionic liquid [DBUH][4-F-PhO]. Subsequently, a certain amount of 4-fluorophenol and ethylene glycol (EG) were added to achieve a molar ratio of 1:2:2 between the ionic liquid, 4-fluorophenol, and EG. The resulting ternary solvent system was designated [DBUH][4-F-PhO]:4-F-PhOH:EG (1:4:2).

[0033] Example 5

[0034] In a glass test tube with an inner diameter of 10 mm, about 2.0 g of the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:3) prepared in Example 1 of the present invention was added, and then CO2 gas was slowly introduced at a flow rate of 50 mL / min. The absorption gas pressure was 0.1 MPa and the temperature was controlled at 25°C. The absorption process was weighed using an electronic analytical balance until absorption equilibrium was reached. At equilibrium, the ratio of the molar amount of CO2 captured by the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:3) to the molar amount of [DBUH][4-F-PhO] contained in the [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:3) was 0.90 mol CO2 / mol [DBUH][4-F-PhO].

[0035] Example 6

[0036] In a glass test tube with an inner diameter of 10 mm, about 2.0 g of the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:2) prepared in Example 2 of the present invention was added, and then CO2 gas was slowly introduced at a flow rate of 50 mL / min. The absorption gas pressure was 0.1 MPa and the temperature was controlled at 25°C. The absorption process was weighed using an electronic analytical balance until absorption equilibrium was reached. At equilibrium, the ratio of the molar amount of CO2 captured by the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:2) to the molar amount of [DBUH][4-F-PhO] contained in the [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:2) was 0.84 mol CO2 / mol [DBUH][4-F-PhO].

[0037] Example 7

[0038] In a glass test tube with an inner diameter of 10 mm, approximately 2.0 g of the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:2:2) prepared in Example 3 of the present invention was added, and then CO2 gas was slowly introduced at a flow rate of 50 mL / min. The absorption gas pressure was 0.1 MPa and the temperature was controlled at 25°C. The absorption process was weighed using an electronic analytical balance until absorption equilibrium was reached. At equilibrium, the ratio of the molar amount of CO2 captured by the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:2:2) to the molar amount of [DBUH][4-F-PhO] contained in the [DBUH][4-F-PhO]:4-F-PhOH:EG (1:2:2) was 0.69 mol CO2 / mol [DBUH][4-F-PhO].

[0039] Example 8

[0040] In a glass test tube with an inner diameter of 10 mm, about 2.0 g of the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:4:2) prepared in Example 4 of the present invention was added, and then CO2 gas was slowly introduced at a flow rate of 50 mL / min. The absorption gas pressure was 0.1 MPa and the temperature was controlled at 25°C. The absorption process was weighed using an electronic analytical balance until absorption equilibrium was reached. At equilibrium, the ratio of the molar amount of CO2 captured by the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:4:2) to the molar amount of [DBUH][4-F-PhO] contained in the [DBUH][4-F-PhO]:4-F-PhOH:EG (1:4:2) was 0.44 mol CO2 / mol [DBUH][4-F-PhO].

[0041] By comparing the experimental results of Examples 5-8, the following conclusion is drawn: by changing the content of the components in the ternary solvent system, the absorption capacity of CO2 by the ternary solvent can be adjusted.

[0042] Example 9

[0043] After the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:3) in Example 5 of the present invention reached absorption equilibrium for CO2, N2 was introduced into the solvent system at a flow rate of 50 mL / min and a desorption temperature of 60°C. After about 65 minutes, all the CO2 captured by the solvent was desorbed.

[0044] Example 10

[0045] After the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:1:2) in Example 6 of the present invention reached absorption equilibrium for CO2, N2 was introduced into the solvent system at a flow rate of 50 mL / min and a desorption temperature of 50°C. After about 95 minutes, all the CO2 captured by the solvent was desorbed.

[0046] Example 11

[0047] After the solvent [DBUH][4-F-PhO]:4-F-PhOH:EG (1:2:2) in Example 7 of the present invention reached absorption equilibrium for CO2, N2 was introduced into the solvent system at a flow rate of 50 mL / min and a desorption temperature of 30°C. After about 105 minutes, all the CO2 captured by the solvent was desorbed.

[0048] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that further improvements can be made to the present invention. In short, according to the principles of the present invention, this application is intended to include any changes, uses or improvements to the present invention, including changes that depart from the disclosed scope in this application and are made using conventional techniques known in the art.

Claims

1. A method for capturing CO2 using a ternary solvent system formed by a superbase ionic liquid and an organic compound, comprising the following steps: 1) preparing a ternary solvent system, wherein the ternary solvent system consists of a superbase ionic liquid, a phenolic organic compound, and an alcoholic organic compound; The molar ratio of the superbase ionic liquid to the phenolic organic compound and the alcohol organic compound is: 1:1-6:2-10; The superbase ionic liquid is synthesized by acid-base reaction between a superbase and a phenolic substance; in, The superbase used to synthesize the superbase ionic liquid is selected from at least one of tetramethylguanidine (TMG), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD); The phenolic substance used to synthesize the superbase ionic liquid is selected from the group consisting of: phenol, 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-trifluoromethylphenol, 2,4-difluorophenol, 4-fluoro-3-methylphenol, 2-methoxy-4-methylphenol, 2-methoxy-4-propylphenol, 2,6-dimethoxyphenol, thymol, carvacrol, eugenol, and vanillin; The phenolic organic compound used to constitute the ternary solvent system is selected from at least one of phenol, 2-fluorophenol, 3-fluorophenol, 4-fluorophenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-trifluoromethylphenol, 2,4-difluorophenol, 4-fluoro-3-methylphenol, 2-methoxy-4-methylphenol, 2-methoxy-4-propylphenol, 2,6-dimethoxyphenol, thymol, carvacrol, eugenol, and vanillin; The alcohol organic compound used to form the ternary solvent system is selected from at least one of butanol, leaf alcohol, ethylene glycol, butanediol, diethylene glycol, triethylene glycol, and polyethylene glycol; 2) The carbon dioxide-containing gas is introduced into a container containing the ternary solvent system, and the pressure and temperature are controlled and then captured.

2. The method according to claim 1, wherein: In step 1), the ternary solvent system is prepared by the following method: mixing a superbase and a phenolic substance in an equal molar ratio, reacting under heating and stirring, and cooling to room temperature to obtain a superbase ionic liquid; mixing the superbase ionic liquid, a phenolic organic substance, and an alcohol organic substance at room temperature and stirring to obtain a ternary solvent system; The reaction time is 1-4 h.

3. The method according to claim 1 or 2, wherein: In step 2), the pressure of the CO2 gas is 0.005 to 0.1 MPa, and the capture temperature is 20-70°C.

4. The method according to claim 1 or 2, characterized in that: The method further comprises the following operations: after absorption saturation, introducing an inert gas into the obtained saturated solution, heating, and desorbing CO2 to recover the ternary solvent system.

5. The method according to claim 4, characterized in that: The flow rate of the inert gas is 40-100 mL / min; The inert gas is specifically N2; The desorption temperature is 25-80°C.