Method for absorbing carbon dioxide by using choline eutectic solvent as absorbent

Abstract

The invention relates to a method for using a choline eutectic solvent as a carbon dioxide absorbent. A choline eutectic solvent is used in the method. Wherein the choline eutectic solvent is prepared by mixing choline chloride (ChCl) and ethanolamine (MEA) according to a molar ratio of 1: 5. Placing the round-bottom flask filled with ChCl and MEA in a constant-temperature magnetic stirring oil bath pan, and heating and stirring for more than 3 hours at the temperature of 100 DEG C; and after a uniform and transparent solution is formed in the flask, taking out the solution from the oil bath pan, and standing to room temperature. Transferring into a reagent bottle, and pasting a label for later use. The choline deep-eutectic solvent is simple in preparation method and low in toxicity, and is an efficient carbon dioxide absorbent.

Description

[Technical field]

[0001] The invention belongs to the field of green chemistry and chemical engineering, and specifically relates to a method for absorbing carbon dioxide by a choline-based low eutectic solvent. [Background technology]

[0002] As the global warming problem becomes increasingly serious, carbon dioxide, as the main greenhouse gas, has become the focus of global attention. Reducing carbon dioxide emissions is crucial to mitigating climate change and achieving sustainable development goals. Therefore, it is necessary to develop efficient carbon dioxide capture technology. Choline-based low eutectic solvents are a new generation of environmentally friendly solvents for natural product extraction. Choline chloride (ChCl)-based low eutectic solvents have good adsorption functions for polar gases such as CO2. Currently, there are some limitations in the commonly used carbon dioxide absorption methods in industry, such as amine absorption. For example, traditional amine absorbents have problems such as strong corrosiveness, volatility, and degradation to produce toxic substances, which not only damages the equipment and increases maintenance costs, but also may cause potential harm to the environment and human health. In addition, the desorption energy consumption in the amine absorption process is high, resulting in high costs for the entire carbon dioxide capture process, which limits its large-scale application. Choline-based low eutectic solvents have the advantages of low toxicity and biodegradability, which are in line with the development concept of green chemistry. They have little impact on the environment during use and disposal, and are an environmentally friendly solvent choice. This type of solvent has good solubility in carbon dioxide and can effectively absorb carbon dioxide. At the same time, by changing the type of choline salt, the type of complexing agent and the molar ratio between them, the physicochemical properties of the low eutectic solvent, such as melting point, viscosity, conductivity, etc., can be adjusted to meet the needs of different carbon dioxide absorption application scenarios. Choline compounds such as choline chloride are usually abundant in source, relatively cheap and easy to obtain, which is conducive to their large-scale production and application, thereby reducing the cost of carbon dioxide capture.

[0003] Therefore, the mixed solvent of choline low eutectic solvent-organic solvent stands out among carbon dioxide absorbers due to its significant advantages such as good absorption performance, low raw material cost, simple preparation process, low corrosiveness, and good selectivity. It helps to reduce carbon dioxide emissions, alleviate various environmental problems caused by climate change, promote sustainable development, and contribute to environmental protection. [Summary of the invention]

[0004] The present invention provides a method for preparing a solvent for absorbing carbon dioxide. The method uses a choline-based low eutectic solvent as a carbon dioxide absorbing solvent, which can not only be widely used in industry, but also can alleviate atmospheric problems such as the greenhouse effect caused by carbon dioxide.

[0005] [Technical solution]

[0006] The present invention aims at solving the problems of carbon dioxide absorption solvents and proposes a method for absorbing carbon dioxide with a choline-based low eutectic solvent, which not only achieves the purpose of efficiently absorbing carbon dioxide, but also makes the process cleaner and more environmentally friendly. The present invention is achieved through the following technical solutions.

[0007] A method for absorbing carbon dioxide using a choline-based deep eutectic solvent as an absorbent comprises the following steps:

[0008] (1) Prepare a choline-based low eutectic solvent. Place choline chloride (ChCl) in a vacuum drying oven to dry and dehydrate; weigh the dried choline chloride (ChCl); weigh ethanolamine (MEA) at a molar ratio of choline chloride (ChCl) to ethanolamine (MEA) of 1:5. (2) Add the weighed choline chloride (ChCl) and ethanolamine (MEA) into a round-bottom flask and mix evenly. Add a stirring magnet and seal the round-bottom flask with a lid. (3) Place the round-bottom flask containing choline chloride (ChCl) and ethanolamine (MEA) in a constant temperature magnetic stirring oil bath at 100°C and heat and stir for more than 3 hours. When a uniform and transparent solution is formed in the flask, remove it from the oil bath and let it stand to room temperature. Transfer it to a reagent bottle, label it, and set aside. (4) As Figure 2 By changing the opening of the N2, O2, and CO2 valves and observing the sizes of F1, F2, F3, and F4, the composition of CO2 in the mixed gas is controlled to simulate the actual gas composition. The gas reaches the tubular heat exchanger through the pipeline, changing the temperature of the gas to meet the process conditions at different temperatures. (5) The mixed gas then enters the designed device, passes through the mesh vent and the induced draft fan, is absorbed by the mixed solvent in the absorption unit, and then leaves from the upper box cover. (6) Finally, the remaining gas is collected by the remaining gas collection device, and the molar mass of the absorbed CO2 is calculated by judging the composition of the remaining gas.

[0009] According to another preferred embodiment of the present invention, it is characterized in that the molar ratio of ChCl to MEA is 1:5.

[0010] According to another preferred embodiment of the present invention, it is characterized in that the ChCl and MEA need to be synthesized at 373.15K.

[0011] According to another preferred embodiment of the present invention, it is characterized in that the stirring rate during the synthesis process is 300 rpm to 800 rpm.

[0012] According to another preferred embodiment of the present invention, it is characterized in that the constant temperature stirring time during the synthesis process is more than 180 minutes.

[0013] According to another preferred embodiment of the present invention, it is characterized in that, in the simulated absorption of carbon dioxide, at 363.15K, the molar ratio of carbon dioxide to the choline low eutectic solvent is 0.26.

[0014] [Beneficial Effects]

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) This method uses a mixed solvent of a choline-based low eutectic solvent and an organic solvent to absorb carbon dioxide, thereby improving the carbon dioxide absorption efficiency. The raw material source is abundant and easy to obtain, which is conducive to large-scale production and application.

[0017] (2) This method has the advantages of simple process, less investment in equipment, and high efficiency in absorbing carbon dioxide. The absorbent used is a mixed solvent of a choline low eutectic solvent and an organic solvent, which has the advantages of simple preparation, easy recovery, and good chemical and thermal stability.

Brief Description of the Drawings

[0018] Figure 1 The present invention is a process flow chart of synthesizing choline low eutectic solvent.

[0019] Figure 2 This is a flow chart of the device for testing the absorption of carbon dioxide of the present invention

[0020] Figure 3 This is a flow chart of the absorption experiment of carbon dioxide by the choline deep eutectic solvent of the present invention [Specific implementation method]

[0021] Embodiment 1:

[0022] The prepared eutectic solvent of choline chloride (ChCl) and ethanolamine (MEA) is placed in a gas absorption device, a certain amount of carbon dioxide is introduced, and the temperature of the system is adjusted by a heat exchanger so that the carbon dioxide entering the gas absorption device is fully mixed with the choline eutectic solvent at a certain temperature. After a certain period of time, the molar mass of the absorbed carbon dioxide is calculated by the residual gas collection device. The molar ratio of carbon dioxide to choline eutectic solvent composed of ChCl and MEA in a molar ratio of 1:5 is 0.28 at 363.15K.

[0023] Embodiment 2:

[0024] The prepared eutectic solvent of choline chloride (ChCl) and ethanolamine (MEA) is placed in a gas absorption device, a certain amount of carbon dioxide is introduced, and the temperature of the system is adjusted by a heat exchanger so that the carbon dioxide entering the gas absorption device is fully mixed with the choline eutectic solvent at a certain temperature. After a certain period of time, the molar mass of the absorbed carbon dioxide is calculated by the residual gas collection device. The molar ratio of carbon dioxide to choline eutectic solvent composed of CHCl and MEA in a molar ratio of 1:5 is 0.23 at 363.15K.

[0025] Embodiment 3:

[0026] The prepared low eutectic solvent of choline chloride (ChCl) and ethanolamine (MEA) is placed in a gas absorption device, a certain amount of carbon dioxide is introduced, and the temperature of the system is adjusted by a heat exchanger so that the carbon dioxide entering the gas absorption device is fully mixed with the choline low eutectic solvent at a certain temperature. After a certain period of time, the molar mass of the absorbed carbon dioxide is calculated by the residual gas collection device. The molar ratio of carbon dioxide to choline low eutectic solvent composed of ChCl and MEA in a molar ratio of 1:5 is 0.26 at 363.15K.

[0027] Embodiment 4:

[0028] The prepared low eutectic solvent of choline chloride (ChCl) and ethanolamine (MEA) is placed in a gas absorption device, a certain amount of carbon dioxide is introduced, and the temperature of the system is adjusted by a heat exchanger so that the carbon dioxide entering the gas absorption device is fully mixed with the choline low eutectic solvent at a certain temperature. After a certain period of time, the molar mass of the absorbed carbon dioxide is calculated by the residual gas collection device. The molar ratio of carbon dioxide to choline low eutectic solvent composed of ChCl and MEA in a molar ratio of 1:5 is 0.24 at 363.15K.

[0029] Embodiment 5:

[0030] The prepared eutectic solvent of choline chloride (ChCl) and ethanolamine (MEA) is placed in a gas absorption device, a certain amount of carbon dioxide is introduced, and the temperature of the system is adjusted by a heat exchanger so that the carbon dioxide entering the gas absorption device is fully mixed with the choline eutectic solvent at a certain temperature. After a certain period of time, the molar mass of the absorbed carbon dioxide is calculated by the residual gas collection device. The molar ratio of carbon dioxide to choline eutectic solvent composed of CHCl and MEA in a molar ratio of 1:5 is 0.29 at 363.15K.

Claims

1. A method for absorbing carbon dioxide using a choline-based deep eutectic solvent as an absorbent, characterized in that: Includes steps: (1) preparing a choline-based low eutectic solvent, placing choline chloride (CHCl) in a vacuum drying oven for drying and dehydration; weighing the dried choline chloride (CHCl); and weighing ethanolamine (MEA) at a molar ratio of choline chloride (CHCl) to ethanolamine (MEA) of 1:

5. (2) Add weighed choline chloride (CHCl) and ethanolamine (MEA) into a round-bottom flask and mix well. Add a magnetic stirrer and seal the round-bottom flask with a lid. (3) Place the round-bottom flask containing choline chloride (ChCl) and ethanolamine (MEA) in a constant temperature magnetic stirring oil bath at 100°C and heat and stir for more than 3 hours. When a uniform and transparent solution is formed in the flask, remove it from the oil bath and let it stand at room temperature. Transfer it to a reagent bottle, label it, and set aside. (4) As shown in Figure 2, by changing the opening of the N2, O2, and CO2 valves and observing the size of F1, F2, F3, and F4, the composition of CO2 in the mixed gas is controlled to simulate the actual gas composition. The gas reaches the tubular heat exchanger through the pipeline, changing the gas temperature to meet the process conditions at different temperatures. (5) The mixed gas then enters the designed device, passes through the mesh vent and the induced draft fan, is absorbed by the mixed solvent in the absorption unit, and then leaves from the upper box cover. (6) Finally, the remaining gas is collected by the remaining gas collection device, and the molar mass of the absorbed CO2 is calculated by judging the composition of the remaining gas.

2. According to another preferred embodiment of the present invention, it is characterized in that: The molar ratio of CHCl to MEA is 1:

5.

3. According to another preferred embodiment of the present invention, it is characterized in that: The CHCl and MEA need to be synthesized at 373.15K.

4. According to another preferred embodiment of the present invention, it is characterized in that: The stirring rate during the synthesis process was 300 rpm to 800 rpm.

5. According to another preferred embodiment of the present invention, it is characterized in that: During the synthesis process, the constant temperature stirring time is more than 180 minutes.

6. According to another preferred embodiment of the present invention, it is characterized in that: In the simulated absorption of carbon dioxide, at 363.15K, the molar ratio of carbon dioxide to the choline deep eutectic solvent is 0.26.

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