CN114702397A - A kind of synthetic method of carbon dioxide absorbent and application thereof - Google Patents

Abstract

The invention discloses a synthesis method and application of a carbon dioxide absorbent. The carbon dioxide absorbent is 2-((3-aminopropyl)(ethyl)amino)ethanol. The preparation method takes ethanolamine and acrylonitrile as raw materials, reacts at low temperature for a period of time, then briefly heats the reaction, steams the unreacted material, and then adds a reducing agent to react to obtain 2-((3-aminopropyl)(ethyl)amino ) ethanol, the yield is 75%-80%. 2-((3-aminopropyl)(ethyl)amino)ethanol is used as carbon dioxide absorber, it is configured into an aqueous solution with a concentration of 0.5mol/L-3mol/L, absorbs carbon dioxide at 10℃-80℃, 80 ℃-120 ℃ desorb carbon dioxide; the volume fraction of the absorbed carbon dioxide can be 0%-99%; compared with the existing common amine carbon dioxide absorbers, the 2-((3-aminopropyl) ( The performance of ethyl)amino)ethanol to absorb carbon dioxide should be excellent, which is reflected in the larger absorption capacity, faster absorption rate, faster desorption rate, higher cycle desorption capacity, and lower regeneration energy consumption.

Description

A kind of synthetic method of carbon dioxide absorbent and application thereof

technical field

The invention relates to the field of carbon dioxide control and emission reduction, in particular to a synthesis method of 2-((3-aminopropyl)(ethyl)amino)ethanol and its application as a carbon dioxide absorbent.

Background technique

With the continuous development of human society and the acceleration of the pace of modern industry, people are mining mining in large quantities, and the emissions of combustion products and automobile exhausts increase rapidly, thus causing the content of carbon dioxide in the atmosphere to skyrocket and the thickness of the earth's atmosphere to increase, leading to global warming. and a series of environmental issues. As a potential chemical resource, how to efficiently capture and store carbon dioxide has become a very important international research topic. Among the absorption methods of carbon dioxide, the chemical absorption method is the most widely used. The gas is washed with a chemically active absorbent, and the carbon dioxide and the absorbent chemically react to form metastable compounds, and then the products are decomposed and released under certain conditions. Carbon dioxide, the desorbed solution is recycled. The chemical absorption method has experienced the development process from the hot potash method, the benfeier method to the organic amine method, and the treatment level is gradually increasing.

The absorption of carbon dioxide by organic amine method is a hot research topic at present, because this method has the characteristics of large absorption capacity, good absorption effect, fast absorption rate, and recyclable absorbent.

However, the organic amine solvents currently used for _CO capture have some disadvantages. For example, primary amines (MEA) and secondary amines (DEA) have faster reaction rates during _CO absorption, but require relatively high consumption during desorption. The large amount of energy to release the absorbed CO ₂ also means that there is a large amount of solvent volatilization, resulting in higher regeneration costs; and the carbamate generated after the CO ₂ is absorbed is more corrosive and easy to damage equipment. cause some damages. Tertiary amine absorbents (such as N-methyldiethanolamine, MDEA) require less energy consumption in the _CO desorption process than primary and secondary amines, but their reaction rates in the _CO absorption process are higher than those of primary and secondary amines. Secondary amines are much lower and certain additives are required to increase their absorption rate. Therefore, the existing organic amines cannot well meet the requirements of high speed, high capacity and low energy consumption in industrialization.

Therefore, the development of new absorbents with high rate, high capacity and low energy consumption is a new trend in the development of carbon dioxide capture.

The structural formula of 2-((3-aminopropyl)(ethyl)amino)ethanol is:

At present, the compound is mainly used in pharmaceutical intermediates. The present invention provides its use as a _CO absorbent and a method for synthesizing 2-((3-aminopropyl)(ethyl)amino)ethanol. Compared with the existing absorbing solvent, 2-((3-aminopropyl)(ethyl)amino)ethanol The absorption performance of (3-aminopropyl)(ethyl)amino)ethanol is better than that of existing and commonly used absorption solvents such as ethanolamine (MEA), N-methyldiethanolamine (MDEA), and it has a faster absorption rate and Large absorption capacity, and lower energy consumption for regeneration.

SUMMARY OF THE INVENTION

Technical scheme one of the present invention is:

A synthetic method of 2-((3-aminopropyl)(ethyl)amino)ethanol, comprising:

(1) Acrylonitrile (compound I) and ethanolamine (compound II) are stirred and reacted at a certain temperature for a period of time; after the reaction is completed, the mixture is briefly heated; then the unreacted material is distilled off under vacuum at 100°C to 120°C to obtain 3-[ Ethyl(2-hydroxyethyl)amino]propionitrile (compound III);

(2) Dissolve the catalyst and 3-[ethyl(2-hydroxyethyl)amino]propionitrile in the solvent respectively, and slowly add 3-[ethyl(2-hydroxyethyl)amino]propionitrile dropwise to the catalyst at low temperature The solution was reacted for 1.5-3 h. After the reaction was completed, the reaction was quenched, and the solvent was evaporated to obtain 2-((3-aminopropyl)(ethyl)amino)ethanol (compound III).

The synthetic route is as follows:

In the step (1), the molar ratio of acrylonitrile to ethanolamine is preferably 1.1-1.5, more preferably 1.3.

In the step (1), the reaction time of ethanolamine and acrylonitrile is 3h-6h, preferably 5h.

In the step (1), the reaction temperature of 3-[ethyl(2-hydroxyethyl)amino]propionitrile is preferably 60°C-90°C, more preferably 70°C-80°C.

In the step (2), the molar ratio of the catalyst to 3-[ethyl(2-hydroxyethyl)amino]propionitrile is 1.5-3, more preferably 2.

The catalyst used in the step (2) is preferably sodium borohydride, lithium aluminum hydride, or borane complex, more preferably lithium aluminum hydride.

In the step (2), the reaction time of lithium aluminum hydride and 3-[ethyl(2-hydroxyethyl)amino]propionitrile is 1-3h, preferably 2h.

The solvent used in the step (2) is preferably tetrahydrofuran, diethyl ether and ethyl acetate, more preferably tetrahydrofuran.

The low temperature in the step (2) is 0°C-5°C.

The second technical solution of the present invention is

A kind of application of 2-((3-aminopropyl)(ethyl)amino)ethanol as carbon dioxide absorbent:

The application of the 2-((3-aminopropyl)(ethyl)amino)ethanol as carbon dioxide absorbent, the method is to prepare 2-((3-aminopropyl)(ethyl)amino)ethanol for 0.5 The aqueous solution of mol/L-3mol/L is used as carbon dioxide absorption liquid, preferably 2mol/L; and the absorption temperature of the carbon dioxide absorption liquid is controlled to be 100 ℃-80 ℃, preferably 30 ℃-60 ℃; the gas pressure to be absorbed is 0.1-3MPa ; the volume fraction of carbon dioxide in the gas is 0%-99%, preferably 10%-30%; the regeneration temperature of the absorbent is 80°C-120°C, preferably 90°C-100°C.

The advantage of the present invention is that a simple route for synthesizing 2-((3-aminopropyl)(ethyl)amino)ethanol is provided. And 2-((3-aminopropyl)(ethyl)amino)ethanol is used as a carbon dioxide absorber, and its structure has a tertiary amine and a primary amine, and the tertiary amine in the molecule can promote faster and more primary amines. It absorbs carbon dioxide and the presence of side chain hydroxyl groups makes it more efficient in mass transfer when it is configured into an aqueous solution. As shown in Figure 1, 2-((3-aminopropyl)(ethyl)amino)ethanol (HEEPDA) has a larger _CO absorption capacity relative to ethanolamine (MEA) and N-methyldiethanolamine (MDEA) and a faster absorption rate; as shown in Figure 2, by comparing the maximum and minimum loadings of the three, it can be seen that 2-((3-aminopropyl)(ethyl)amino)ethanol has a higher circulation As can be seen from Figure 3, after 6 regeneration cycles of 2-((3-aminopropyl)(ethyl)amino)ethanol, the amount of _CO2 absorbed is relatively stable, indicating that it has a strong stability sex.

Description of drawings

Figure 1 is a comparative curve of CO ₂ absorption loading performance of ethanolamine (MEA), N-methyldiethanolamine (MDEA), and 2-((3-aminopropyl)(ethyl)amino)ethanol (HEEPDA) absorbents.

Figure 2 is a graph comparing the maximum and minimum loadings of MEA, MDEA and 2-((3-aminopropyl)(ethyl)amino)ethanol (HEEPDA) absorbents.

Figure 3 is a graph comparing regeneration amounts of MEA, MDEA, and 2-((3-aminopropyl)(ethyl)amino)ethanol (HEEPDA) absorbents.

Detailed ways

Example 1

Take 47 g of acrylonitrile and add it dropwise to 50 g of ethanolamine in 90 min. The unreacted material was evaporated to dryness under reduced pressure at °C to obtain 3-[ethyl(2-hydroxyethyl)amino]propionitrile. Dissolve 1.1 g of sodium borohydride in 25 ml of tetrahydrofuran solution under ice bath and _N2 protection; take 2 ml of 3-[ethyl(2-hydroxyethyl)amino]propionitrile, dissolve in 20 ml of tetrahydrofuran, and slowly add dropwise to the hydroboration In the sodium solution, after the dropwise addition was completed, the reaction was carried out at 0 °C for 2 h. After the completion of the reaction, hydrolyzed with concentrated hydrochloric acid and transferred to a clean beaker, then filtered, rinsed with tetrahydrofuran solution, and evaporated the solvent under reduced pressure to obtain 2-((3-aminopropyl)(ethyl)amino)ethanol , the yield is 50%.

Example 2

47 g of acrylonitrile was taken and added dropwise to 50 g of ethanolamine in 90 min. The reaction temperature was controlled at 20 °C. After the dropwise addition was completed, the reaction was stirred for 3 h. After the reaction was completed, the reaction mixture was transferred to a water bath and heated at 80 °C for 30 min. The unreacted material was evaporated to dryness under reduced pressure at °C to obtain 3-[ethyl(2-hydroxyethyl)amino]propionitrile. Dissolve 1.1 g of lithium aluminum hydride in 22 ml of tetrahydrofuran solution under ice bath and _N2 protection; take 2 ml of 3-[ethyl(2-hydroxyethyl)amino]propionitrile, dissolve in 20 ml of tetrahydrofuran, and slowly add dropwise to lithium aluminum hydride The solution was added dropwise and reacted at 0°C for 2h. After the reaction was completed, 1.1 g of deionized water was slowly added dropwise to the reaction solution, deionized water was added dropwise for 10 min, and then 1.1 g of 15% NaOH solution was added dropwise to quench the reaction, then filtered, and the solvent was evaporated under reduced pressure to obtain 2. -((3-aminopropyl)(ethyl)amino)ethanol, 70% yield.

Example 3

56.5 g of acrylonitrile was taken and added dropwise to 50 g of ethanolamine in 90 min. The reaction temperature was controlled at 30 °C. After the dropwise addition was completed, the reaction was stirred for 5 h. After the reaction was completed, the reaction mixture was transferred to a water bath and heated at 80 °C for 30 min. The unreacted material was evaporated to dryness under reduced pressure at 110°C to obtain 3-[ethyl(2-hydroxyethyl)amino]propionitrile. Dissolve 1.1 g of lithium aluminum hydride in 22 ml of tetrahydrofuran solution under ice bath and _N2 protection; take 2 ml of 3-[ethyl(2-hydroxyethyl)amino]propionitrile, dissolve in 20 ml of tetrahydrofuran, and slowly add dropwise to lithium aluminum hydride The solution was added dropwise and reacted at 5°C for 2h. After the reaction was completed, 1.1 g of deionized water was slowly added dropwise to the reaction solution, deionized water was added dropwise for 10 min, and then 1.1 g of 15% NaOH solution was added dropwise to quench the reaction, then filtered, and the solvent was evaporated to dryness under reduced pressure to obtain 2. -((3-aminopropyl)(ethyl)amino)ethanol, 80% yield.

Example 4: Absorption capacity investigation

2-((3-aminopropyl)(ethyl)amino)ethanol was prepared into a 2mol/l aqueous solution as a carbon dioxide absorbent. Under the condition of normal pressure of 0.1MPa, the volume fraction of _CO2 was controlled to be 10%, and 2 -((3-Aminopropyl)(ethyl)amino)ethanol uptake as a function of time. The results showed that 2-((3-aminopropyl)(ethyl)amino)ethanol had the largest absorption capacity compared to the other two carbon dioxide absorbers. As shown in Figure 1.

Example 5: Maximum and Minimum Loads

2-((3-aminopropyl)(ethyl)amino)ethanol was prepared into a 2mol/l aqueous solution as a carbon dioxide absorbent. Under the condition of normal pressure of 0.1MPa, the volume fraction of _CO2 was controlled to be 10%, and the temperature reached 50 °C. The maximum loading was measured after the absorption was saturated; the minimum loading was measured after the desorption was completed at 90°C. The results show that 2-((3-aminopropyl)(ethyl)amino)ethanol has the largest active absorption capacity compared to the other two carbon dioxide absorbers. as shown in picture 2.

Example 6: Cycle capacity

2-((3-aminopropyl)(ethyl)amino)ethanol was prepared into a 2mol/l aqueous solution as a carbon dioxide absorbent. Under the condition of normal pressure of 0.1MPa, the volume fraction of _CO2 was controlled to be 10%, and after the absorption was saturated , the load was measured, and after desorption at 90 °C for 2 hours, the absorption was carried out again. After repeated many times, the performance did not deteriorate. As shown in Figure 3.

Claims (9)

1. A synthetic method and its application of carbon dioxide absorbent, said absorbent is 2- ((3-aminopropyl) (ethyl) amino) ethanol, said synthetic method, characterized by that:

(1) taking acrylonitrile and ethanolamine as starting raw materials, and stirring and reacting for a period of time at a certain temperature; after the reaction is completed, heating the mixture; evaporating unreacted reactants at 100-120 ℃ under negative pressure to obtain 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile;

(2) respectively dissolving a catalyst and 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile in a solvent, dropwise adding the 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile into the catalyst solution at low temperature, reacting for a period of time, quenching the reaction, and evaporating the solvent to obtain the 2- ((3-aminopropyl) (ethyl) amino) ethanol.

2. The method of synthesizing 2- ((3-aminopropyl) (ethyl) amino) ethanol according to claim 1 wherein the molar ratio of acrylonitrile to ethanolamine in step (1) is 1.1 to 1.5; the molar ratio of the catalyst to the 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile in the step (2) is 1.5-3.

3. The method for synthesizing 2- ((3-aminopropyl) (ethyl) amino) ethanol according to claim 1, wherein the step (1) ethanolamine and acrylonitrile are reacted for 3h to 6 h; the reaction time of the catalyst in the step (2) and 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile is 1-3h, and preferably 2 h.

4. The method for synthesizing 2- ((3-aminopropyl) (ethyl) amino) ethanol according to claim 1, wherein the reaction temperature of ethanolamine and acrylonitrile in step (1) is 20 ℃ to 35 ℃; the reaction temperature of the 3- [ ethyl (2-hydroxyethyl) amino ] propionitrile in the step (1) is 60-90 ℃; the low temperature in the step (2) is 0-5 ℃.

5. The method for synthesizing 2- ((3-aminopropyl) (ethyl) amino) ethanol according to claim 1, wherein in step (2) the catalyst is sodium borohydride, lithium aluminum hydride, borane complex, preferably lithium aluminum hydride.

6. The method for synthesizing 2- ((3-aminopropyl) (ethyl) amino) ethanol according to claim 1, wherein the solvent in step (2) is tetrahydrofuran, diethyl ether, ethyl acetate, preferably tetrahydrofuran.

7. Use according to claim 1, wherein the concentration of 2- ((3-aminopropyl) (ethyl) amino) ethanol in the carbon dioxide absorbing solution is from 0.5mol/L to 3mol/L, preferably 2 mol/L.

8. The use according to claim 1, wherein the absorption temperature of the carbon dioxide absorption liquid is 10 ℃ to 80 ℃; the regeneration temperature of the carbon dioxide absorbent is 80-120 ℃.

9. Use according to claim 1, wherein the absorbed gas has a pressure of 0.1-3 MPa; the volume fraction of carbon dioxide in the gas is 0-99%.

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