Water-phase mixed amine absorbent and application thereof

Abstract

The invention belongs to the technical field of gas purification and separation, and particularly relates to a water-phase mixed amine absorbent and application thereof. Polyamine without tertiary amine N atoms is used as an absorption main agent, tertiary amine containing one N atom is used as a desorption main agent, polyamine containing one tertiary amine N atom is used as an activating agent, the desorption main agent is easy to regenerate, and the alkaline characteristic of the desorption main agent can strengthen the proton transfer process, so that the proton transfer efficiency is improved. Therefore, the mixed amine has the characteristics of high regeneration rate, high regeneration efficiency and low regeneration energy consumption; the absorption main agent contains a plurality of amino groups, so that the mixed amine has the characteristics of high absorption rate and high absorption capacity; meanwhile, the activating agent can activate the mixed amine absorbent, so that the mixed amine absorbent has efficient absorption performance and desorption performance at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of gas purification and separation, and in particular relates to a water-phase mixed amine absorbent and application thereof. Background Art

[0002] Since the Industrial Revolution, with the rapid economic development, the concentration of greenhouse gases such as CO2 in the atmosphere has increased year by year, leading to global warming. The end-of-pipe control of CO2 represented by CO2 capture, utilization and storage (CCUS) technology is a bottom-line technology for multiple industries to achieve zero or even negative carbon emissions, and is of decisive significance for the large-scale low-carbon utilization of fossil energy.

[0003] Post-combustion CO2 capture (PCC) is an important part of CCUS technology. PCC mainly includes physical absorption, chemical absorption, adsorption, membrane separation, biological method, etc. As a long-term and stable concentrated emission source of CO2, the flue gas from coal-fired power plants has a large flue gas flow rate and a low CO2 partial pressure. Combined with the maturity and adaptability of the current PCC technical process, the chemical absorption method is the most competitive technology for commercial application. Chemical absorbent is the core of chemical absorption technology. Monoethanolamine (MEA) is the earliest chemical absorbent to achieve commercial application. It has the advantage of fast absorption rate, but in actual application, it has problems such as small circulation capacity, high regeneration energy consumption, fast degradation rate, and strong corrosiveness. Therefore, the development of new absorbents with fast absorption rate, high regeneration rate, large circulation capacity, and low regeneration energy consumption is the key to reducing the energy consumption of carbon capture systems and improving economic benefits. Summary of the invention

[0004] The purpose of the present invention is to provide an aqueous mixed amine absorbent and application thereof. The aqueous mixed amine absorbent provided by the present invention has the advantages of high absorption rate, high regeneration rate, large circulation capacity and low regeneration energy consumption.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides an aqueous mixed amine absorbent, the aqueous mixed amine absorbent comprising a main agent and an activator, the main agent comprising an absorption main agent and a desorption main agent, the absorption main agent is a polyamine containing no tertiary amine N atom, the desorption main agent is a tertiary amine containing one N atom, and the activator is a polyamine containing one tertiary amine N atom;

[0007] The pKa values ​​of the activator, the main absorbing agent and the main desorbing agent decrease in sequence.

[0008] Preferably, the molar ratio of the absorption main agent, the activator and the desorption main agent is 1:0.1-4:0.1-3.9.

[0009] Preferably, the main absorption agent includes one or more of hydroxyethylethylenediamine, diethylenetriamine and ethylenediamine.

[0010] Preferably, the desorption main agent includes one or more of N-methyldiethanolamine, diethylaminoethanol, N,N-dimethylethanolamine and triethanolamine.

[0011] Preferably, the activator is aminoethylpiperazine.

[0012] Preferably, the aqueous phase mixed amine absorbent also includes water;

[0013] When the aqueous mixed amine absorbent also includes water, the mass percentage of the main agent and the activator is 30-50%.

[0014] The present invention also provides the use of the aqueous phase mixed amine absorbent described in the above technical solution in carbon dioxide capture.

[0015] Preferably, during the application, the absorption temperature of the aqueous phase mixed amine absorbent is 30-50°C.

[0016] Preferably, after the water-phase mixed amine absorbent captures carbon dioxide, the process further includes regenerating the water-phase mixed amine absorbent.

[0017] Preferably, the regeneration temperature is 90-120°C;

[0018] The regeneration pressure is 1-1.2 bar.

[0019] The present invention provides an aqueous mixed amine absorbent, the aqueous mixed amine absorbent comprises a main agent and an activator, the main agent comprises an absorption main agent and a desorption main agent, the absorption main agent is a polyamine without tertiary amine N atom, the desorption main agent is a tertiary amine containing one N atom, and the activator is a polyamine containing one tertiary amine N atom; the pKa values ​​of the activator, the absorption main agent, and the desorption main agent are successively reduced. The present invention uses a polyamine without tertiary amine N atom as the absorption main agent, a tertiary amine containing one N atom as the desorption main agent, and a polyamine containing one tertiary amine N atom as the activator, wherein the tertiary amine containing one N atom is easy to regenerate, and its alkalinity can strengthen the proton transfer process, so that the mixed amine has the characteristics of fast regeneration rate, high regeneration efficiency and low regeneration energy consumption; the absorption main agent contains multiple amino groups, so the mixed amine has the characteristics of high absorption rate and high absorption amount; at the same time, the activator can activate the mixed amine absorbent, and activate the absorption and desorption processes at the same time, so that the mixed amine absorbent has both efficient absorption performance and desorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The absorption curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0021] Figure 2 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0022] Figure 3 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1 to 2 of the present invention;

[0023] Figure 4 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0024] Figure 5 The cyclic absorption curve of the mixed amine absorbent solution obtained in Example 1 and Comparative Examples 1-2 of the present invention;

[0025] Figure 6 The absorption curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention;

[0026] Figure 7 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention;

[0027] Figure 8 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention;

[0028] Fig. 9 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention;

[0029] Fig.10 The cyclic absorption curve of the mixed amine absorbent solution obtained in Example 2 and Comparative Examples 3 to 4 of the present invention;

[0030] Fig.11 The absorption curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention;

[0031] Fig.12 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention;

[0032] Fig.13 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention;

[0033] Fig.14 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention;

[0034] Fig.15 This is the circulation absorption curve of the mixed amine absorbent solution obtained in Example 3 of the present invention and Comparative Examples 5-6. DETAILED DESCRIPTION

[0035] The present invention provides an aqueous mixed amine absorbent, the aqueous mixed amine absorbent comprising a main agent and an activator, the main agent comprising an absorption main agent and a desorption main agent, the absorption main agent is a polyamine containing no tertiary amine N atom, the desorption main agent is a tertiary amine containing one N atom, and the activator is a polyamine containing one tertiary amine N atom;

[0036] The pKa values ​​of the activator, the main absorbing agent and the main desorbing agent decrease in sequence.

[0037] In the present invention, the structural formula of the absorption main agent, the desorption main agent and the activator is as follows:

[0038]

[0039] The N atom subscript represents the number of amino functional groups, and CnHm represents the alkyl functional group.

[0040] In the present invention, the molar ratio of the absorption main agent, the activating agent and the desorption main agent is preferably 1:0.1-4:0.1-3.9, specifically 1:1:3 or 1:0.5:3.5.

[0041] In the present invention, the main absorbent preferably includes one or more of hydroxyethylethylenediamine (AEEA), diethylenetriamine (DETA) and ethylenediamine (EDA). In the present invention, the pKa values ​​of hydroxyethylethylenediamine (AEEA), diethylenetriamine (DETA) and ethylenediamine (EDA) at 25°C are 9.44, 9.76 and 9.93 respectively.

[0042] In the present invention, the main desorption agent includes one or more of N-methyldiethanolamine (MDEA), diethylaminoethanol (DEEA), N,N-dimethylethanolamine (DMEA) and triethanolamine (TEA). In the present invention, the pKa values ​​of N-methyldiethanolamine (MDEA), diethylaminoethanol (DEEA), N,N-dimethylethanolamine (DMEA) and triethanolamine (TEA) at 25°C are 8.65, 9.75, 9.49 and 7.85 respectively.

[0043] In the present invention, the activator is preferably aminoethylpiperazine (AEP); the pKa value of the aminoethylpiperazine (AEP) at 25° C. is 10.11.

[0044] In the present invention, the aqueous mixed amine absorbent preferably also includes water, and the water is preferably deionized water; when the aqueous mixed amine absorbent also includes water, the mass percentage of the main agent and the activator is preferably 30-50%, specifically 30%, 35%, 40%, 45% or 50%.

[0045] The present invention also provides the use of the aqueous phase mixed amine absorbent described in the above technical solution in carbon dioxide capture.

[0046] The present invention has no special limitation on the application process, and those skilled in the art may adopt the process known to those skilled in the art. In the present invention, during the application process, the absorption temperature of the aqueous phase mixed amine absorbent is preferably 30-50°C.

[0047] In the present invention, after the aqueous mixed amine absorbent captures carbon dioxide, the aqueous mixed amine absorbent is preferably regenerated. In the present invention, the regeneration temperature is preferably 90-120°C; the regeneration pressure is preferably 1-1.2 bar.

[0048] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0049] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Example 1

[0051] Take 6.62g of aminoethylpiperazine (AEP), 5.51g of hydroxyethylethylenediamine (AEEA), 17.87g of N-methyldiethanolamine (MDEA) and 70g of deionized water respectively, mix them evenly, and prepare 100g of mixed amine absorbent solution with a molar ratio of 1:1:3, in which the total mass fraction of AEP+AEEA+MDEA is 30wt%, and let it stand for use.

[0052] Example 2

[0053] Take 6.59 g of aminoethylpiperazine (AEP), 5.26 g of diethylenetriamine (DETA), 18.15 g of N-methyldiethanolamine (MDEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 1:1:3, in which the total mass fraction of AEP+DETA+MDEA is 30 wt%, and let it stand for use.

[0054] Example 3

[0055] Take 5.69 g of aminoethylpiperazine (AEP), 4.59 g of hydroxyethylethylenediamine (AEEA), 19.72 g of triethanolamine (TEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 1:1:3, in which the total mass fraction of AEP+AEEA+TEA is 30 wt %, and let it stand for use.

[0056] Comparative Example 1

[0057] Take 5.68g of hydroxyethylethylenediamine (AEEA), 24.32g of N-methyldiethanolamine (MDEA) and 70g of deionized water respectively, mix them evenly, and prepare 100g of mixed amine absorbent solution with a molar ratio of 1:4, in which the total mass fraction of AEEA+MDEA is 30wt%, and let it stand for use.

[0058] Comparative Example 2

[0059] Take 11.04 g of hydroxyethylethylenediamine (AEEA), 18.96 g of N-methyldiethanolamine (MDEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 2:3, wherein the total mass fraction of AEEA+MDEA is 30 wt %, and set aside for use.

[0060] Comparative Example 3

[0061] Take 5.36g of diethylenetriamine (DETA), 24.64g of N-methyldiethanolamine (MDEA) and 70g of deionized water respectively, mix them evenly, and prepare 100g of mixed amine absorbent solution with a molar ratio of 1:4, in which the total mass fraction of DETA+MDEA is 30wt%, and let it stand for use.

[0062] Comparative Example 4

[0063] Take 10.99 g of diethylenetriamine (DETA), 19.01 g of N-methyldiethanolamine (MDEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 2:3, in which the total mass fraction of DETA+MDEA is 30 wt%, and let it stand for use.

[0064] Comparative Example 5

[0065] Take 4.46 g of hydroxyethylethylenediamine (AEEA), 25.54 g of triethanolamine (TEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 1:4, wherein the total mass fraction of AEEA+TEA is 30 wt %, and set aside for use.

[0066] Comparative Example 6

[0067] Take 9.53 g of hydroxyethylethylenediamine (AEEA), 20.47 g of triethanolamine (TEA) and 70 g of deionized water respectively, mix them evenly, and prepare 100 g of a mixed amine absorbent solution with a molar ratio of 2:3, wherein the total mass fraction of AEEA+TEA is 30 wt %, and set aside for use.

[0068] Performance Testing

[0069] The mixed amine absorbent solutions obtained in the examples and comparative examples were placed at normal pressure and 40° C. to absorb pure CO 2 . The system after CO 2 absorption was placed at a stirring speed of 50 rpm and an oil bath temperature of 120° C. to desorb CO 2 .

[0070] Among them, the absorption amount is defined as: the amount of CO2 absorbed by 1 mol of amine (mol);

[0071] The absorption rate is defined as: the amount of CO2 absorbed by 1 mol of amine per unit time (min) (mol);

[0072] The desorption amount is defined as: the amount of CO2 desorbed by 1 mol of amine (mol);

[0073] The CO2 desorption rate is defined as: the amount of CO2 (mol) desorbed by 1 mol of amine per unit time (min);

[0074] The cycle capacity is defined as the amount of CO2 absorbed by the lean solution generated after the rich solution is fully regenerated at 120°C (mol).

[0075] (1) Results Analysis of Example 1 and Comparative Examples 1 to 2

[0076] Figure 1 The absorption curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention; Figure 2 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention; Figure 3 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1 to 2 of the present invention; Figure 4 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1-2 of the present invention; Figure 5 The cyclic absorption curves of the mixed amine absorbent solutions obtained in Example 1 and Comparative Examples 1 to 2 of the present invention; wherein "AEEA+AEP+MDEA; 1:1:3" is Example 1, "AEEA+MDEA; 1:4" is Comparative Example 1, and "AEEA+MDEA; 2:3" is Comparative Example 2;

[0077] Depend on Figures 1 to 5It can be seen that for the AEEA+MDEA mixed amine absorbent with AEEA as the main absorption agent and MDEA as the main desorption agent, its characteristics are that as the proportion of AEEA increases and the proportion of MDEA decreases, the absorption performance increases, while the desorption performance decreases, and it is impossible to have both efficient CO2 absorption performance and desorption performance. Compared with the mixed amine solution with a molar ratio of AEEA+MDEA of 1:4 (i.e., Comparative Example 1), AEP is added as an activator, so that AEP replaces part of the desorption main agent MDEA to form a mixed amine solution with a molar ratio of AEP+AEEA+MDEA of 1:1:3 (i.e., Example 1).

[0078] In terms of absorption performance, the absorption amount and absorption rate of Example 1 are significantly improved, and its saturated absorption amount is 0.98 mol CO2 / mol amine, while the saturated absorption amount of Comparative Example 1 is 0.87 mol CO2 / mol amine; in terms of desorption performance, the replacement of the main desorption agent does not reduce the equilibrium desorption amount, but increases it. The equilibrium desorption amount of Example 1 is 0.93 mol CO2 / mol amine, while the equilibrium desorption amount of Comparative Example 1 is 0.85 mol CO2 / mol amine;

[0079] The maximum desorption rate slightly decreased, and the maximum CO2 desorption rate of Example 1 was 0.060 mol CO2 / (mol amine min), while the maximum CO2 desorption rate of Comparative Example 1 was 0.065 mol CO2 / (mol amine min). This shows that compared with the mixed amine solution of Comparative Example 1 which has high CO2 desorption performance but not high CO2 absorption performance, the addition of the activator AEP can improve the CO2 absorption performance while ensuring the CO2 desorption performance.

[0080] Compared with the mixed amine solution with a molar ratio of AEEA+MDEA of 2:3 (i.e., comparative example 2), AEP is added as an activator, so that AEP replaces part of the absorption main agent AEEA to form a mixed amine solution with a molar ratio of AEP+AEEA+MDEA of 1:1:3 (i.e., example 1). In terms of absorption performance, the replacement of the absorption main agent did not reduce the absorption performance, and the equilibrium absorption amount was equivalent to that of comparative example 2. The absorption rate of example 1 in the initial stage was lower than that of comparative example 2; but when the CO2 loading amount was higher than 0.28 mol CO2 / mol amine, its absorption rate was higher than that of comparative example 2; in terms of desorption performance, the desorption amount and desorption rate of example 1 were significantly higher than those of comparative example 2. This shows that compared with the mixed amine solution of comparative example 2, which has high-efficiency CO2 absorption performance but not high-efficiency CO2 desorption performance, the addition of the activator AEP can improve the CO2 desorption performance while ensuring the CO2 absorption performance.

[0081] The mixed amine solution of Example 1 has stable CO2 cyclic absorption and desorption amounts, and both of the cyclic absorption and desorption amounts are higher than those of Comparative Examples 1 and 2.

[0082] In summary, AEP activator is suitable for AEEA+MDEA mixed amine absorbent with AEEA as the main absorption agent and MDEA as the main desorption agent. The AEEA+AEP+MDEA mixed amine solution can have both efficient CO2 absorption performance and CO2 desorption performance.

[0083] (2) Analysis of the results of Example 2 and Comparative Examples 3 to 4

[0084] Figure 6 The absorption curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention; Figure 7 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention; Figure 8 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention; Fig. 9 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention; Fig.10 The cyclic absorption curves of the mixed amine absorbent solutions obtained in Example 2 and Comparative Examples 3 to 4 of the present invention; wherein, "DETA+AEP+MDEA; 1:1:3" is Example 2, "DETA+MDEA; 1:4" is Comparative Example 3, and "DETA+MDEA; 2:3" is Comparative Example 4;

[0085] Depend on Figures 6 to 10 It can be known that for the DETA+MDEA mixed amine absorbent with DETA as the main absorption agent and MDEA as the main desorption agent, its characteristics are that as the proportion of DETA increases and the proportion of MDEA decreases, the absorption performance increases, while the desorption performance decreases, and it is impossible to have both efficient CO2 absorption performance and desorption performance. Compared with the mixed amine solution with a molar ratio of DETA+MDEA of 1:4 (Comparative Example 3), AEP is added as an activator to make AEP replace part of the desorption main agent MDEA to form a mixed amine solution with a molar ratio of DETA+AEP+MDEA of 1:1:3 (ie, Example 2). In terms of absorption performance, the absorption amount and absorption rate of Example 2 are significantly improved, and its saturated absorption amount is 1.13 mol CO2 / mol amine, while the saturated absorption amount of Comparative Example 3 is 1.00 mol CO2 / mol amine; the absorption rate in the initial stage of Example 2 (0.032 mol CO2 / (mol amine min)) is also higher than that of Comparative Example 3 (0.02 mol CO2 / (mol amine min));

[0086] In terms of desorption performance, the replacement of the main desorption agent did not reduce the equilibrium desorption amount, but increased it. The equilibrium desorption amount of Example 2 was 0.94 mol CO2 / mol amine, while the equilibrium desorption amount of Comparative Example 3 was 0.88 mol CO2 / mol amine;

[0087] The maximum desorption rate slightly decreased, and the maximum CO2 desorption rate of Example 2 was 0.061 mol CO2 / (mol amine min), while the maximum CO2 desorption rate of Comparative Example 3 was 0.062 mol CO2 / (mol amine min). This shows that compared with the mixed amine solution of Comparative Example 3 which has high CO2 desorption performance but not high CO2 absorption performance, the addition of the activator AEP can improve the CO2 absorption performance while ensuring the CO2 desorption performance.

[0088] Compared with the mixed amine solution with a molar ratio of DETA+MDEA of 2:3 (Comparative Example 4), AEP was added as an activator to make AEP replace part of the absorption main agent DETA to form a mixed amine solution with a molar ratio of DETA+AEP+MDEA of 1:1:3 (Example 2). In terms of absorption performance, the replacement of the absorption main agent did not reduce the absorption performance, but improved it. The equilibrium absorption amount of Example 2 (1.13 mol CO2 / mol amine) was slightly higher than that of Comparative Example 4 (1.12 mol CO2 / mol amine); the absorption rate of Example 2 (0.032 mol CO2 / (mol amine min)) was also higher than that of Comparative Example 4 (0.028 mol CO2 / (mol amine min));

[0089] In terms of desorption performance, the desorption amount (0.94 mol CO2 / mol amine) and desorption rate (0.061 mol CO2 / (mol amine min)) of Example 2 are significantly higher than the desorption amount (0.90 mol CO2 / mol amine) and desorption rate (0.059 mol CO2 / (mol amine min)) of Comparative Example 4. The desorption rate (83%) of Example 2 is also higher than that of Comparative Example 4 (80%). This shows that compared with the mixed amine solution of Comparative Example 4 which has high CO2 absorption performance but not high CO2 desorption performance, the addition of the activator AEP can improve the CO2 desorption performance while ensuring the CO2 absorption performance.

[0090] The mixed amine solution of Example 2 has stable CO2 cyclic absorption and desorption amounts, and both of the cyclic absorption and desorption amounts are higher than those of Comparative Examples 3 and 4.

[0091] In summary, AEP activator is suitable for DETA+MDEA mixed amine absorbent with DETA as the main absorption agent and MDEA as the main desorption agent. DETA+AEP+MDEA mixed amine solution can have both efficient CO2 absorption performance and CO2 desorption performance.

[0092] (3) Analysis of the results of Example 3 and Comparative Examples 5 to 6

[0093] Fig.11The absorption curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention; Fig.12 The absorption rate curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention; Fig.13 The desorption amount curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention; Fig.14 The desorption rate curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention; Fig.15 The cyclic absorption curves of the mixed amine absorbent solutions obtained in Example 3 and Comparative Examples 5 to 6 of the present invention; wherein, "AEEA+AEP+TEA; 1:1:3" is Example 3, "AEEA+TEA; 1:4" is Comparative Example 5, and "AEEA+TEA; 2:3" is Comparative Example 6;

[0094] Depend on Figures 11 to 15 It can be known that for the AEEA+TEA mixed amine absorbent with AEEA as the main absorption agent and TEA as the main desorption agent, its characteristics are that as the proportion of AEEA increases and the proportion of TEA decreases, the absorption performance increases, while the desorption performance decreases, and it is impossible to have both efficient CO2 absorption performance and desorption performance. Compared with the mixed amine solution with a molar ratio of 1:4 for AEEA+TEA (i.e., Comparative Example 5), AEP is added as an activator to make AEP replace part of the desorption main agent TEA to form a mixed amine solution with a molar ratio of 1:1:3 for AEEA+AEP+TEA (i.e., Example 3). In terms of absorption performance, the absorption amount and absorption rate of Example 3 are significantly improved, and its saturated absorption amount is 0.84 molCO2 / molamine, while the saturated absorption amount of Comparative Example 5 is 0.65 molCO2 / molamine; the absorption rate in the initial stage of Example 3 (0.035 molCO2 / (molaminemin)) is also higher than the absorption rate of Comparative Example 5 (0.032 molCO2 / (molaminemin));

[0095] In terms of desorption performance, the replacement of the main desorption agent did not reduce the equilibrium desorption amount and the maximum desorption rate, but increased them. The equilibrium desorption amount of Example 3 was 0.77 mol CO2 / mol amine, while the equilibrium desorption amount of Comparative Example 5 was 0.63 mol CO2 / mol amine; the maximum desorption rate of Example 3 was 0.050 mol CO2 / (mol amine min), while the maximum desorption rate of Comparative Example 5 was 0.048 mol CO2 / (mol amine min). This shows that compared with the mixed amine solution of Comparative Example 5 which has high CO2 desorption performance but not high CO2 absorption performance, the addition of the activator AEP can improve the CO2 absorption performance while ensuring the CO2 desorption performance.

[0096] Compared with the mixed amine solution with a molar ratio of 2:3 of AEEA+TEA (i.e., comparative example 6), AEP was added as an activator, so that AEP replaced part of the absorption main agent AEEA to form a mixed amine solution with a molar ratio of 1:1:3 of AEEA+AEP+TEA (i.e., example 3). In terms of absorption performance, the replacement of the absorption main agent did not reduce the absorption performance, but improved it. The equilibrium absorption amount of example 3 (0.84 mol CO2 / mol amine) was significantly higher than that of comparative example 6 (0.73 mol CO2 / mol amine), and the absorption rate in the initial stage of example 3 (0.035 mol CO2 / (mol amine min)) was also higher than that of comparative example 6 (0.031 mol CO2 / (mol amine min));

[0097] In terms of desorption performance, the desorption amount (0.77 mol CO2 / mol amine) and desorption rate (0.050 mol CO2 / (mol amine min)) of Example 3 are both higher than the desorption amount (0.73 mol CO2 / mol amine) and desorption rate (0.049 mol CO2 / (mol amine min)) of Comparative Example 6. This shows that compared with the mixed amine solution of Comparative Example 6 which has high CO2 absorption performance but not high CO2 desorption performance, the addition of the activator AEP can improve the CO2 desorption performance while ensuring the CO2 absorption performance.

[0098] The mixed amine solution of Example 3 has stable CO2 cyclic absorption and desorption amounts, and its cyclic absorption and desorption amounts are higher than those of Comparative Examples 5 and 6.

[0099] In summary, AEP activator is suitable for AEEA+TEA mixed amine absorbent with AEEA as the main absorption agent and TEA as the main desorption agent. The AEEA+AEP+TEA mixed amine solution can have both efficient CO2 absorption performance and CO2 desorption performance.

[0100] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An aqueous phase mixed amine absorbent, characterized in that: The aqueous phase mixed amine absorbent comprises a main agent and an activator, wherein the main agent comprises an absorption main agent and a desorption main agent, wherein the absorption main agent is a polyamine containing no tertiary amine N atom, the desorption main agent is a tertiary amine containing one N atom, and the activator is a polyamine containing one tertiary amine N atom; The pKa values ​​of the activator, the main absorbing agent and the main desorbing agent decrease in sequence.

2. The aqueous phase mixed amine absorbent according to claim 1, characterized in that: The molar ratio of the absorption main agent, the activating agent and the desorption main agent is 1:0.1-4:0.1-3.

9.

3. The aqueous phase mixed amine absorbent according to claim 1 or 2, characterized in that: The main absorption agent includes one or more of hydroxyethylethylenediamine, diethylenetriamine and ethylenediamine.

4. The aqueous phase mixed amine absorbent according to claim 1 or 2, characterized in that: The main desorption agent includes one or more of N-methyldiethanolamine, diethylaminoethanol, N,N-dimethylethanolamine and triethanolamine.

5. The aqueous phase mixed amine absorbent according to claim 1 or 2, characterized in that: The activator is aminoethylpiperazine.

6. The aqueous phase mixed amine absorbent according to claim 1 or 2, characterized in that: The aqueous phase mixed amine absorbent also includes water; When the aqueous mixed amine absorbent also includes water, the mass percentage of the main agent and the activator is 30-50%.

7. Use of the aqueous phase mixed amine absorbent according to any one of claims 1 to 6 in carbon dioxide capture.

8. The use according to claim 7, characterized in that: During the application, the absorption temperature of the aqueous phase mixed amine absorbent is 30-50°C.

9. The use according to claim 7, characterized in that: After the water-phase mixed amine absorbent captures carbon dioxide, the method further includes regenerating the water-phase mixed amine absorbent.

10. The use according to claim 9, characterized in that: The regeneration temperature is 90-120°C; The regeneration pressure is 1-1.2 bar.

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