Carbon dioxide absorbent

Abstract

The invention relates to a carbon dioxide absorbent, which comprises the following raw material components: primary and secondary amine, tertiary amine and water, and is characterized in that the raw material components further comprise a phase separating agent, and the phase separating agent is obtained by chemical reaction of alanine and inorganic quaternary ammonium base; the carbon dioxide absorbent is combined with CO2 to form a split-phase system, the split-phase system comprises an upper phase system and a lower phase system, the upper phase system comprises a first part of the tertiary amine, and the lower phase system comprises a composition with a water shell structure, a composition of primary and secondary amine and CO2, a second part of the tertiary amine and free water; the composition with the water shell layer structure is composed of a phase separating agent and water, and the diameter of the composition with the water shell layer structure is (8 * 10 <-10 >)-(20 * 10 <-10 >) m. The technical problem that an existing carbon dioxide absorbent is high in regeneration energy consumption is solved.

Description

Technical Field

[0001] This application relates to the technical field of carbon dioxide control and emission reduction, and particularly to a carbon dioxide absorbent. Background Art

[0002] Climate change problems caused by the emission of greenhouse gases such as carbon dioxide (CO2) have attracted more and more widespread attention. At present, low-concentration CO2 carbon sources are more abundant, and the scale effect brought by capturing low-concentration carbon sources is more significant, but the difficulty is higher. Absorption based on amines (mainly MEA solution) is the most effective technology for CO2 capture from low-pressure, large-volume gas flows. MEA absorbent has the advantages of rapid reaction, effective absorption of CO2, and relatively cheap amine. When the temperature is relatively low (20 - 40 °C), the reaction proceeds in the forward reaction direction and releases heat; when the temperature is relatively high, the reaction proceeds in the reverse reaction direction and the solution is regenerated. Industrially, the characteristics of the reaction between MEA and CO2 are utilized to achieve the purpose of CO2 recovery (or removal). However, MEA aqueous solution has the disadvantages of low CO2 absorption capacity and high regeneration energy consumption.

[0003] In the actual regeneration process, the main energy consumption involves the energy required for the decomposition of CO2 compounds or the evaporation of absorbents. Therefore, using a phase change absorbent and only using this absorbent for regeneration to reduce the amount of absorbent required is a practical and effective method. Currently, a series of innovative biphasic solvents have emerged, showing advantageous characteristics such as high-efficiency CO2 absorption, high absorption rate, and low energy consumption. Among these innovative biphasic solvents, amino biphasic solutions have attracted much attention. The usual configuration includes using primary or secondary amines as the main absorbent and tertiary amines as the phase separator. However, these absorbents have two obvious defects: 1) High amine concentration leads to an increase in solution viscosity, thus hindering the absorption process; 2) The loss of volatile amines during the process will all result in high regeneration energy consumption of the absorbent. Summary of the Invention

[0004] This application provides a carbon dioxide absorbent to solve the technical problem of high regeneration energy consumption of existing carbon dioxide absorbents.

[0005] In a first aspect, this application provides a carbon dioxide absorbent, the raw material components of which include: primary and secondary amines, tertiary amines, and water. It is characterized in that the raw material components further include: a phase separation agent, which is obtained by a chemical reaction between alanine and an inorganic quaternary ammonium base;

[0006] The carbon dioxide absorbent combines with CO2 to form a phase separation system, and the phase separation system includes an upper phase system and a lower phase system.

[0007] The upper phase system includes the first part of the tertiary amines.

[0008] The lower phase system includes a composition with a water shell layer structure, a composition of primary and secondary amines and CO2, the secondary amine in the second part, and free water. The composition with the water shell layer structure is composed of a phase separation agent and water, and the diameter of the composition with the water shell layer structure is (8*10 -10 ) to (20*10 -10 ) meters.

[0009] Optionally, relative to 1 volume part of the phase separation system, the lower phase system is 0.18 to 0.90 volume parts.

[0010] Optionally, relative to 1 volume part of the lower phase system, the secondary amine in the second part is 0.05 to 0.2 volume parts.

[0011] Optionally, the volume ratio of the water content in the composition with the water shell layer structure to the free water is (1.1 to 1.6):1.

[0012] Optionally, the inorganic quaternary ammonium base includes at least one of the following: tetramethylammonium hydroxide, tetraethylammonium hydroxide.

[0013] Optionally, relative to 1 weight part of the carbon dioxide absorbent, the phase separation agent is 0.05 to 0.4 weight parts.

[0014] Optionally, relative to 1 weight part of the carbon dioxide absorbent, the phase separation agent is 0.05 to 0.1 weight parts.

[0015] Optionally, the primary and secondary amines include at least one of the following: hydroxyethyl ethylenediamine, diethanolamine, triethylenetetramine; and / or,

[0016] The secondary amines include at least one of the following: 1-ethylimidazole, 1-methylimidazole, 1-butylimidazole.

[0017] Optionally, relative to 1 weight part of the carbon dioxide absorbent, the primary and secondary amines are 0.1 to 0.4 weight parts, the secondary amines are 0.1 to 0.5 weight parts, and the water is 0.05 to 0.2 weight parts.

[0018] Optionally, the process parameters for the combination of the carbon dioxide absorbent and CO2 include: the operating temperature is 20°C to 50°C, the operating pressure is 1 to 3 atmospheres, and the volume fraction of CO2 is 5% to 40%.

[0019] The above technical solutions provided in the embodiments of the present application have the following advantages compared with the prior art:

[0020] The carbon dioxide absorbent provided by the embodiment of the present application has strong hydrophilicity of alanine, strong hydrophilicity and symmetrical structure of inorganic quaternary ammonium base, and the phase separation agent obtained by the neutralization reaction of alanine and inorganic quaternary ammonium base has strong hydrophilicity and stable structure. The carbon dioxide absorbent combines with CO2, and the phase separation agent acts as a trigger during the CO2 absorption process. Through the cooperative-discharge absorption mechanism, a phase separation system is formed. The phase separation agent forms a stable water shell layer structure with water. The small size of the water shell layer structure is beneficial to controlling the viscosity of the lower phase within a reasonable range, and the absorption product does not generate solids due to the agglomeration effect. This structural water shell layer structure combines a large amount of water. Since the tertiary amine does not have a sensitive hydrogen bond donor, it cannot form a strong interaction with other components, which is beneficial to repelling part of the tertiary amine out of the aqueous phase to form a separate phase, and then gradually being discharged from the system and transferred to the upper phase; the primary and secondary amines are the main absorbents, maintaining a high absorption rate of the absorbent for CO2, and thus being transferred to the lower phase. This phase separation system effectively reduces the energy consumption in the regeneration process of the carbon dioxide absorbent and also promotes the absorption of carbon dioxide by the main absorbent, primary and secondary amines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a graph showing the change of a phase separation system with the content of the phase separation agent provided by the embodiment of the present application;

[0024] Figure 2 It is a graph showing the change of a phase separation system with the content of primary and secondary amines provided by the embodiment of the present application;

[0025] Figure 3 It is a curve graph showing the change of the absorption capacity of carbon dioxide absorption with the content of primary and secondary amines and tertiary amines provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0027] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0028] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Additionally, in the description of this application's specification, the terms "include", "comprise", etc. mean "including but not limited to". In this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, "and / or" describes the associated relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this document, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one of the following items", or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0029] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this application can all be obtained through market purchases or can be prepared by existing methods.

[0030] In a first aspect, the present application provides a carbon dioxide absorbent, the raw material components of which include: primary and secondary amines, tertiary amines, and water. It is characterized in that the raw material components further include: a phase separation agent, which is obtained by a chemical reaction between alanine and an inorganic quaternary ammonium base;

[0031] The carbon dioxide absorbent combines with CO2 to form a phase separation system, which includes an upper phase system and a lower phase system.

[0032] The upper phase system includes the first part of the tertiary amines.

[0033] The lower phase system includes a composition with a water shell structure, a composition of primary and secondary amines and CO2, the second part of the tertiary amines, and free water. The composition with a water shell structure is composed of a phase separation agent and water, and the diameter of the composition with a water shell structure is (8*10 -10 ) to (20*10 -10 ) meters.

[0034] In the embodiments of the present application, alanine has strong hydrophilicity, and the inorganic quaternary ammonium base has strong hydrophilicity and a symmetrical structure. The phase separation agent obtained by the neutralization reaction between alanine and the inorganic quaternary ammonium base has strong hydrophilicity and a stable structure. When this carbon dioxide absorbent combines with CO2, the phase separation agent acts as a trigger during the CO2 absorption process. Through the synergy-excretion absorption mechanism, a phase separation system is formed. The phase separation agent and water form a stable water shell structure. The small size of the water shell structure helps to control the viscosity of the lower phase within a reasonable range, and the absorption product does not produce solids due to the aggregation effect. This water shell structure combines a large amount of water. Since the tertiary amines do not have sensitive hydrogen bond donors, they cannot form strong interactions with other components, which is conducive to excluding some of the tertiary amines from the aqueous phase to form a separate phase, and then gradually being excreted from the system and transferred to the upper phase; the primary and secondary amines are the main absorbents, maintaining a relatively high absorption rate of the absorbent for CO2, and thus being transferred to the lower phase. This phase separation system reduces the volume of the phase where carbon dioxide is concentrated, can effectively reduce the energy consumption during the regeneration process, and also promotes the absorption of carbon dioxide by the main absorbent, primary and secondary amines. Exemplarily, the diameter of the above-mentioned composition with a water shell structure can be 8*10 -10 m, 10*10 -10 m, 12*10 -10 m, 13*10 -10 m, 14*10 -10 m, 15*10 -10 m, 16*10 -10 m, 18*10 -10 m, 20*10 -10 m.

[0035] The preparation process of the above phase separator: Dissolve inorganic quaternary ammonium base and alanine in an appropriate amount of deionized water at a molar ratio of 1:1, and stir and react at room temperature for 48 h to obtain a solution. Remove the solvent water from the reaction solution using a rotary evaporator to obtain a viscous liquid, which is the crude product of the ionic liquid. Add anhydrous ethanol for washing and filtration. The solid phase is the excessive alanine, and the liquid phase is concentrated and the washing step is repeated twice to obtain an ethanol solution of the ionic liquid. Rotate and evaporate to remove the solvent ethanol, and after drying, a viscous liquid is obtained, which is the pure product of the ionic liquid, that is, the phase separator, and it is stored sealed for use.

[0036] In some embodiments, relative to 1 volume portion of the phase separation system, the lower phase system is 0.18 volume portion to 0.90 volume portion.

[0037] In the embodiments of the present application, controlling the volume of the above lower phase system is beneficial to regulating the sensible heat during the regeneration process and maintaining an appropriate viscosity of the lower phase; if the volume of the lower phase system is too large, to a certain extent, it will increase the regeneration energy consumption of the carbon dioxide absorbent; if the volume of the lower phase system is too small, to a certain extent, it will cause the viscosity of the rich liquid in the lower phase regeneration to be too large, which is not conducive to the regeneration of the carbon dioxide absorbent. Exemplarily, the above lower phase system can be 0.18 volume portion, 0.2 volume portion, 0.3 volume portion, 0.4 volume portion, 0.5 volume portion, 0.6 volume portion, 0.9 volume portion, etc.

[0038] In some embodiments, relative to 1 volume portion of the lower phase system, the tertiary amine in the second part is 0.05 volume portion to 0.2 volume portion.

[0039] In the embodiments of the present application, the tertiary amine is distributed in the tertiary amine in the first part (upper phase) and the tertiary amine in the second part (lower phase). Controlling the volume of the tertiary amine in the second part of the lower phase system maintains an appropriate phase separation ratio. If the volume of the tertiary amine in the lower phase system is too large, to a certain extent, it will increase the regeneration cycle capacity, increasing the regeneration energy consumption of the carbon dioxide absorbent and the energy consumption of the feed liquid transmission; if the volume of the tertiary amine in the lower phase system is too small, to a certain extent, it will inhibit the proton transfer during the regeneration process, affecting the regeneration efficiency of the carbon dioxide absorbent. Exemplarily, the tertiary amine in the second part can be 0.05 volume portion, 0.10 volume portion, 0.15 volume portion, 0.2 volume portion, etc.

[0040] In some embodiments, the volume ratio of the water content in the composition having a water shell layer structure to the free water is (1.1 to 1.6):1.

[0041] In the embodiments of the present application, the volume of free water in the lower phase is controlled to maintain an appropriate latent heat of regeneration. If the volume of the free water is too large, it will significantly increase the water consumption to a certain extent, thereby increasing the latent heat; if the volume of the free water is too small, it will increase the viscosity to a certain extent, affecting the regeneration efficiency. Exemplarily, the volume ratio of the water content in the composition having the water shell layer structure to the volume of the free water may be 1.1:1, 1.3:1, 1.84:1, 1.5:1, 1.6:1, etc.

[0042] In some embodiments, the inorganic quaternary ammonium base includes at least one of the following: tetramethylammonium hydroxide, tetraethylammonium hydroxide.

[0043] In the embodiments of the present application, tetramethylammonium hydroxide and tetraethylammonium hydroxide are selected to form a stable ionic liquid structure with alanine. Cations with a small relative molecular mass and a symmetric structure can form a stable water shell layer. The phase separation agent obtained by the reaction of tetramethylammonium hydroxide and alanine is abbreviated as [N 1111 [Ala], and the phase separation agent obtained by the reaction of tetraethylammonium hydroxide and alanine is abbreviated as [N 2222 [Ala].

[0044] In some embodiments, relative to 1 part by weight of the carbon dioxide absorbent, the phase separation agent is 0.05 part by weight to 0.4 part by weight.

[0045] In some embodiments, relative to 1 part by weight of the carbon dioxide absorbent, the phase separation agent is 0.05 part by weight to 0.1 part by weight.

[0046] In the embodiments of the present application, the positive effect of controlling the content of the phase separation initiator: regulating an appropriate phase separation time point. If the content is too high, the phase separation will disappear in the later stage of absorption to a certain extent; if the content is too low, the water shell layer cannot be stably formed to a certain extent, thereby inhibiting the phase separation. Exemplarily, the phase separation agent may be 0.05 part by weight, 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, etc. Optionally, the phase separation agent may be 0.05 part by weight to 0.1 part by weight.

[0047] In some embodiments, the primary and secondary amines include at least one of the following: hydroxyethyl ethylenediamine, diethanolamine, triethylenetetramine; and / or,

[0048] The tertiary amines include at least one of the following: 1-ethylimidazole, 1-methylimidazole, 1-butylimidazole.

[0049] In the embodiments of the present application, hydroxyethyl ethylenediamine, diethanolamine, and triethylenetetramine are selected as primary and secondary amines. The excellent primary and secondary amine groups can maintain a high absorption rate. 1-ethylimidazole and N,N-dimethylethanolamine are selected as tertiary amines. The above two tertiary amines are excellent proton acceptors and are easily discharged from the aqueous phase during the phase separation process.

[0050] In some embodiments, relative to 1 part by weight of the carbon dioxide absorbent, the primary and secondary amine is 0.1 to 0.4 parts by weight, the tertiary amine is 0.1 to 0.5 parts by weight, and the water is 0.05 to 0.2 parts by weight.

[0051] In the embodiments of the present application, the content of the primary and secondary amine is controlled to maintain an appropriate absorption capacity and absorption rate. If the content of the primary and secondary amine is too high, it will cause excessive viscosity and inhibit absorption to a certain extent. If the content of the primary and secondary amine is too low, the absorption amount will be too low to a certain extent. In the embodiments of the present application, the positive effect of controlling the content of the tertiary amine is to maintain an appropriate phase separation rate and phase separation ratio to ensure the absorption amount. If the content of the tertiary amine is too high, it will cause excessive viscosity and a small absorption capacity to a certain extent. If the content is too low, the phase separation will be inhibited to a certain extent. Controlling the water content can reduce the viscosity, transfer protons, promote the formation of the water shell layer, and improve the absorption rate. If the water content is too high, the regeneration latent heat will increase to a certain extent. If the water content is too low, the rich phase viscosity will increase to a certain extent, affecting the absorption and regeneration rates. Exemplarily, the above primary and secondary amines can be 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight. Optionally, the above primary and secondary amines can be 0.1 to 0.3 parts by weight. The above tertiary amines can be 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight. Optionally, the above tertiary amines can be 0.2 to 0.5 parts by weight. The above water can be 0.05 part by weight, 0.1 part by weight, 0.2 part by weight. Optionally, the above water can be 0.1 to 0.2 parts by weight.

[0052] In some embodiments, the process parameters for the carbon dioxide absorbent to combine with CO2 include: the operating temperature is 20°C to 50°C, the operating pressure is 1 to 3 atmospheres, and the volume fraction of CO2 is 5% to 40%.

[0053] In the embodiments of the present application, the operating temperature is controlled to maintain a high absorption rate; the operating pressure is controlled to avoid the disappearance of the phase interface due to excessive absorption; the volume fraction of CO2 is controlled to ensure the environment for flue gas absorption. Exemplarily, the above-mentioned operating temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc., the operating pressure can be 1 atmosphere, 2 atmospheres, 3 atmospheres, etc., and the volume fraction of CO2 can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0054] The following further elaborates the present application in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0055] The embodiments of the present application provide a carbon dioxide absorbent. Please refer to the raw materials of the carbon dioxide absorbent shown in Table 1 and the raw material content of the carbon dioxide absorbent shown in Table 2.

[0056] Table 1 Raw materials of the carbon dioxide absorbent

[0057] Serial number Primary and secondary amines Tertiary amines Phase separation agent Example 1 Hydroxyethyl ethylenediamine 1-Ethylimidazole Alanine, tetramethylammonium hydroxide Example 2 Hydroxyethyl ethylenediamine 1-Methylimidazole Alanine, tetraethylammonium hydroxide Example 3 Diethanolamine 1-Ethylimidazole Alanine, tetramethylammonium hydroxide Example 4 Triethylenetetramine 1-Ethylimidazole Alanine, tetraethylammonium hydroxide Example 5 Triethylenetetramine 1-Butylimidazole Alanine, tetramethylammonium hydroxide Comparative Example 1 Hydroxyethyl ethylenediamine 1-Ethylimidazole / Comparative Example 2 Ethanolamine / /

[0058] Table 2 Raw material content (wt%) of the carbon dioxide absorbent

[0059] Serial number Primary and secondary amines Tertiary amines Phase separation agent Water Example 1 20％ 50％ 10％ 20％ Example 2 20％ 50％ 10％ 20％ Example 3 20％ 50％ 10％ 20％ Example 4 20％ 50％ 10％ 20％ Example 5 20％ 50％ 10％ 20％ Comparative Example 1 20％ 50％ / 30％ Comparative Example 2 30％ / / 70％

[0060] The carbon dioxide in the power plant flue gas with an original carbon dioxide content of 10 - 40% is absorbed and treated by the carbon dioxide absorbents prepared in the above-mentioned Examples 1 - 5 and Comparative Examples 1 - 2. Among them, the configured carbon dioxide absorbent is introduced into the configured saturated water and then into the simulated flue gas for absorption. The gas to be treated containing carbon dioxide is brought into full contact with the carbon dioxide absorbent in an environment of 40°C and 1.5 bar pressure for absorption to obtain a phase-separated system. Please refer to the distribution of the phase-separated system shown in Table 3, and the lower phase of the phase-separated system is sent to the regeneration tower for regeneration. Please refer to the test results of the absorption performance of the carbon dioxide absorbent shown in Table 4.

[0061] Table 3 Distribution of the phase-separated system

[0062]

[0063] Table 4 Test results of the absorption performance of the carbon dioxide absorbent

[0064] Serial number Absorption capacity (mol / kg) <![CDATA[Regeneration energy consumption (GJ / tCO2)]]> Regeneration rate % Example 1 4.23 2.01 81％ Example 2 3.86 3.59 76％ Example 3 2.86 2.32 70％ Example 4 2.55 2,87 79％ Example 5 3.02 3.04 68％ Comparative Example 1 2.26 4.23 52％ Comparative Example 2 2.42 3.89 44％

[0065] From Tables 1 to 4, with different combinations of primary and secondary amines and different tertiary amines while keeping the phase separation agent unchanged, the regeneration energy consumption of the carbon dioxide absorbent is small. Figure 1 It is a graph showing the change of a phase separation system provided by an embodiment of the present application with the content of the phase separation agent; please refer to Figure 1 , for the raw material components in Example 1, only changing the content of the phase separation agent shows that as the content of the phase separation agent decreases, the absorption amount gradually increases and the proportion of the lower phase gradually decreases. When the content is less than 5%, phase separation cannot occur. Figure 2 It is a graph showing the change of a phase separation system provided by an embodiment of the present application with the content of the primary and secondary amines; please refer to Figure 2 , for the raw material components in Example 1, only changing the content of the primary and secondary amines, the primary and secondary amines represent the main absorbent, indicating that as the proportion of the main absorbent decreases, the volume of the lower phase shrinks accordingly, and when its content is 20%, it is the most reasonable. Figure 3 It is a graph showing the change of the absorption capacity of carbon dioxide absorption provided by an embodiment of the present application with the content of the primary and secondary amines and the tertiary amines; please refer to Figure 3 , the primary and secondary amines represent the main absorbent, and the phase separation represents the tertiary amine, indicating that as the content of the main absorbent increases, the absorption amount gradually rises, and when it reaches 50%, the absorption amount reaches 4.2 mol / kg.

[0066] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A carbon dioxide absorbent, the raw material components including: Primary and secondary amines, tertiary amines, and water, characterized in that the raw material components further include: a phase separation agent obtained by a chemical reaction of alanine and an inorganic quaternary ammonium base; The carbon dioxide absorbent combines with CO2 to form a phase separation system, and the phase separation system includes an upper phase system and a lower phase system. The upper phase system includes the tertiary amine in the first part, and the lower phase system includes a composition with a water shell structure, a composition of primary and secondary amines and CO2, the tertiary amine in the second part, and free water. The composition with a water shell structure is composed of a phase separation agent and water, and the diameter of the composition with a water shell structure is (8*10 -10 ) to (20*10 -10 ) m.

2. The carbon dioxide absorbent according to claim 1, wherein, Relative to 1 volume part of the phase separation system, the lower phase system is 0.18 volume parts to 0.90 volume parts.

3. The carbon dioxide absorbent according to claim 1 or 2, wherein Relative to 1 volume part of the lower phase system, the second part of the tertiary amine is 0.05 volume parts to 0.2 volume parts.

4. The carbon dioxide absorbent according to claim 1, characterized in that, The volume ratio of the water content in the composition having a water shell layer structure to the free water is (1.1 - 1.6):

1.

5. The carbon dioxide absorbent according to claim 1, wherein The inorganic quaternary ammonium base includes at least one of the following: tetramethylammonium hydroxide, tetraethylammonium hydroxide.

6. The carbon dioxide absorbent according to claim 1, wherein Relative to 1 weight part of the carbon dioxide absorbent, the phase separation agent is 0.05 weight parts to 0.4 weight parts.

7. The carbon dioxide absorbent according to claim 6, characterized in that, Relative to 1 weight part of the carbon dioxide absorbent, the phase separation agent is 0.05 weight parts to 0.1 weight parts.

8. The carbon dioxide absorbent according to claim 1, wherein The primary and secondary amines include at least one of the following: hydroxyethyl ethylenediamine, diethanolamine, triethylenetetramine; and / or The tertiary amines include at least one of the following: 1-ethylimidazole, 1-methylimidazole, 1-butylimidazole.

9. The carbon dioxide absorbent according to claim 1 or 8, characterized in that, Relative to 1 weight part of the carbon dioxide absorbent, the primary and secondary amines are 0.1 weight parts to 0.4 weight parts, the tertiary amines are 0.1 weight parts to 0.5 weight parts, and the water is 0.05 weight parts to 0.2 weight parts.

10. The carbon dioxide absorbent according to claim 1, wherein, The process parameters for the combination of the carbon dioxide absorbent and CO2 include: an operating temperature of 20°C to 50°C, an operating pressure of 1 to 3 atmospheres, and a volume fraction of CO2 of 5% to 40%.

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