A mixed amine carbon capture absorbent for carbon dioxide capture and use thereof

Abstract

This invention relates to a mixed amine carbon capture absorbent for carbon dioxide capture. The mixed amine carbon capture absorbent comprises, by mass percentage: 10-30% main absorbent, 2-15% co-absorbent, 0-5% additive, and the balance being water. The main absorbent comprises a polyamine and / or a sterically hindered amine. The polyamine has 2-4 amino groups. The amino groups of the polyamine include any one or a combination of at least two of primary, secondary, and tertiary amino groups. A carbon chain exists between the amino sites of the polyamine. The carbon chain has ≥2 carbon atoms. The co-absorbent comprises a cyclic amine with side chains. The mixed amine carbon capture absorbent of this invention has advantages such as high CO2 loading capacity, high absorption rate, and low regeneration energy consumption. It can achieve efficient and low-energy capture of CO2 from mixed gases and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, and more particularly to a mixed amine carbon capture absorbent for carbon dioxide capture and its application. Background Technology

[0002] Currently, carbon emissions are a serious problem, and chemical absorption is the only carbon capture technology that can be commercialized on a large scale. It is suitable for low-concentration carbon dioxide (CO2) applications. Its absorbent is mainly organic amine absorbent. Among them, mixed amine absorbent combines the advantages of different organic amines and can be applied based on existing processes. It is currently the most promising flue gas decarbonization absorbent for industrial applications.

[0003] Primary and secondary amines such as ethanolamine (MEA) and diethanolamine (DEA) are widely used as primary absorbents due to their advantages such as fast absorption rate and low cost. For example, CN113426249A discloses a novel mixed organic amine CO2 absorbent with MEA as the main component and DETA as an additive, with a CO2 loading of 0.50 mol CO2 / mol amine; CN120771682A discloses a carbon dioxide capture and absorption agent and a capture and absorption method, which is an absorbent with DEA ​​and ethylenediamine as the main agents, with a regeneration rate of 77% and a regeneration energy consumption of 2.68 GJ / t CO2. Tertiary amines such as N-methyldiethanolamine (MDEA) have also become common primary agents in mixed amine absorbents due to their high CO2 loading and low heat of reaction. China Petroleum & Chemical Corporation has developed an absorbent with MDEA and DEA as the main agents, which has high removal rate and regeneration performance. In addition, hindered amines such as 2-amino-2-methyl-1-propanol (AMP) are also favored due to their high CO2 loading capacity. For example, CN104853830A discloses an absorbent containing AMP, which contains a combination of 2-amino-2-methyl-1-propanol (AMP) and 3-aminopropanol (AP) and has strong antioxidant and corrosion resistance.

[0004] Currently, absorbents generally face the dilemma of not being able to simultaneously achieve optimal absorption and desorption performance. Primary and secondary amines, with their fast absorption rates, suffer from low regeneration rates, low CO2 loading, and high regeneration energy consumption. Tertiary amines, while exhibiting excellent regeneration performance and low regeneration energy consumption, have slow reaction rates. Furthermore, common industrial carbon capture processes for CO2 chemical absorption still primarily utilize absorbent systems such as MEA, MDEA, and AMP. Among these, mixed amine absorbents, primarily based on MEA, generally suffer from unsatisfactory absorption and regeneration performance, high regeneration energy consumption, and strong corrosivity, making it difficult to optimize economic benefits. 30% MEA absorbent is a widely used industrial carbon capture absorbent, commonly used as a standard for performance comparison; its CO2 absorption capacity is 0.50 mol CO2 / mol amine, its regeneration rate is 70%, and its regeneration energy consumption is 3.80 GJ·t. -1 CO2; MDEA-based absorbents have slow reaction rates, are prone to foaming, require strict filtration of thermally stable salts, and increase operating costs; AMP is a primary amine, therefore the regeneration energy consumption of this system is still relatively high, and its low thermal stability makes it prone to degradation, resulting in high operating costs. Furthermore, literature reports that mixed amine carbon capture absorbents have absorption capacities of 0.31-1.38 mol CO2 / mol amine, regeneration rates of 50-90%, and regeneration energy consumption of 2.0-3.2 GJ·t. -1 CO2.

[0005] While mixed absorbent systems with the aforementioned absorbents as the main components can compensate for shortcomings to some extent, they are limited by the inherent characteristics of these single organic amines, making it difficult to simultaneously possess excellent absorption and regeneration performance, and the regeneration energy consumption is relatively high. These shortcomings have become obstacles to the large-scale and rapid promotion of these absorbents. Therefore, there is an urgent need to develop novel mixed amine carbon capture and absorption agents that are highly efficient and have low energy consumption. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a mixed amine carbon capture absorbent for carbon dioxide capture and its application. This invention aims to overcome the issues of the inability to simultaneously achieve optimal absorption and desorption performance in carbon capture absorbents, as well as high regeneration energy consumption. The mixed amine carbon capture absorbent of this invention combines the advantages of a primary absorbent (high CO2 absorption capacity and regeneration rate) with that of a secondary absorbent (fast absorption rate and high removal rate), and its simple regeneration process demonstrates the excellent absorption and desorption performance of the absorbent.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 10-30% main absorbent, 2-15% co-absorbent, 0-5% additive, and the balance being water.

[0009] The main absorbent comprises a polyamine and / or a sterically hindered amine; the polyamine has 2-4 amino groups; the amino groups of the polyamine include any one or a combination of at least two of primary, secondary, and tertiary amino groups; a carbon chain exists between the amino sites of the polyamine; the carbon chain has ≥2 carbon atoms;

[0010] The absorption aid comprises cyclic amines with side chains.

[0011] For organic amines, primary and secondary amines mainly achieve CO2 capture by forming carbamates, limiting their CO2 absorption capacity to 0.5 mol CO2 / mol amine, and their desorption rate is relatively slow. For tertiary amines, they interact with CO2 during the capture process to form HCO3-. - This gives it a theoretical CO2 absorption capacity of 1 mol CO2 / mol amine; while hindered amines, although they can have primary and secondary amine structures, will rapidly hydrolyze into HCO3- due to steric hindrance, as the resulting unstable carbamates will be formed. - In organic amine solutions rich in CO2, HCO3- - The presence of ions promotes the deprotonation of organic amines, enabling the absorbent to accelerate desorption while increasing its CO2 absorption capacity, which is beneficial for subsequent recycling.

[0012] The preferred primary absorbent of this invention is tetramethylpropanediamine, which has a tertiary amino polyamine molecular structure, and its molecular structure is as follows: It has ≥2 tertiary amine structures, a theoretical CO2 loading > 1 mol CO2 / mol amine, and will form HCO3 after absorbing CO2. - This process promotes the deprotonation of organic amines and, acting as a proton acceptor, directly releases CO2. This allows the main absorbent to accelerate desorption while increasing its CO2 absorption capacity, thereby improving its regeneration rate and giving the absorbent excellent regeneration performance. Furthermore, absorbents with multiple amino sites and long chains (≥3 carbon atoms) exhibit more prominent kinetic characteristics, thus enabling the main absorbent to possess both excellent absorption and desorption performance.

[0013] The mass fraction of the main absorbent in the mixed amine carbon capture and absorbent is 10-30%, such as 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0014] The mass fraction of the co-absorbent in the mixed amine carbon capture and absorbent is 2-15%, such as 2%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] The mass fraction of the additive in the mixed amine carbon capture and absorbent is 0-5%, such as 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0016] As a preferred embodiment of the present invention, the polyamine comprises any one or a combination of at least two of diethylenetriamine, triethylenediamine, hydroxyethylethylenediamine, tetraethylenepentamine, and tetramethylpropylenediamine. Typical but non-limiting examples of such combinations include: diethylenetriamine and tetramethylpropylenediamine, triethylenediamine and hydroxyethylethylenediamine, hydroxyethylethylenediamine and tetraethylenepentamine, and tetraethylenepentamine and tetramethylpropylenediamine. In this invention, tetramethylpropylenediamine is preferred.

[0017] Preferably, the sterically hindered amine comprises 2-amino-2-methyl-1-propanol or 2-amino-2-methyl-1,3-propanediol.

[0018] As a preferred embodiment of the present invention, the absorbent includes any one of N-methylpiperazine, 2-methylpiperazine or N-aminoethylpiperazine, and N-methylpiperazine is preferred as the absorbent in the present invention.

[0019] The preferred absorption aid of this invention is N-methylpiperazine, with a molecular structure of a tertiary amino polyamine, and its molecular structure is as follows: It possesses both tertiary and secondary amino structures, and its amino groups are replaced by methyl groups, which can improve its CO2 capacity and absorption rate, giving the absorbent excellent kinetic properties and thus excellent absorption rate.

[0020] Preferably, the total amine concentration of the mixed amine carbon capture and absorbent is 10-50%, such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] Preferably, the mass ratio of the primary absorbent to the co-absorbent is 2:1 to 10:1, such as 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] Since the CO2 capture of mixed amine absorbents follows a shuttle mechanism, the ratio of promoter to shuttle affects the absorption rate of the absorbent. At the same time, the proportion of different components affects the absorption capacity, regeneration rate and regeneration energy consumption of the absorbent. By adjusting the proportion of each component in the mixed amine absorbent, the absorption and regeneration performance of the absorbent can be further improved, and the formulation can be optimized.

[0023] As a preferred technical solution of the present invention, the additive includes any one or a combination of at least two of the following: anti-degradation agent, corrosion inhibitor, or defoamer. Typical but non-limiting examples of such combinations include: anti-degradation agent and corrosion inhibitor, anti-degradation agent and defoamer, and anti-degradation agent, corrosion inhibitor, and defoamer.

[0024] As a preferred embodiment of the present invention, the anti-degradation agent includes any one or a combination of at least two of ethylenediaminetetraacetic acid (EDTA), sodium potassium tartrate, or hydroquinone. Typical but non-limiting examples of such combinations include: EDTA and hydroquinone, EDTA and sodium potassium tartrate, and sodium potassium tartrate and hydroquinone.

[0025] As a preferred embodiment of the present invention, the corrosion inhibitor includes any one of sodium sulfite, sodium vanadate, sodium metavanadate, or sodium thiosulfate.

[0026] As a preferred embodiment of the present invention, the defoamer includes any one of polydimethylsiloxane, polyethylene glycol, or polyether.

[0027] In a second aspect, the present invention provides an application of the mixed amine carbon capture absorbent as described in the first aspect, wherein the mixed amine carbon capture absorbent is used to capture CO2 from a mixed gas, specifically comprising: fully contacting the mixed amine carbon capture absorbent with a mixed gas containing CO2, performing absorption treatment, and obtaining a mixed amine carbon capture absorbent rich solution loaded with CO2.

[0028] The rich solution of the mixed amine carbon trapping absorbent is heated and desorbed to obtain a poor solution of the mixed amine carbon trapping absorbent.

[0029] In this invention, the CO2 capture of the mixed amine carbon capture absorbent follows a shuttle mechanism: primary and secondary amines react rapidly with CO2 at the gas-liquid interface to form carbamates, which then permeate into the liquid phase and react with excess tertiary or sterically hindered amines to produce HCO3. -The original organic amine molecules are released again, returning to the gas-liquid interface to react with CO2 once more. In this process, primary and secondary amines act as promoters and shuttles, reducing mass transfer resistance and promoting the rapid entry of CO2 into the liquid phase. Therefore, organic amine composite solutions containing a small amount of primary or tertiary amine structures can rapidly increase the CO2 absorption rate, and their reaction kinetics are mainly influenced by their structural factors. The substitution of alkyl groups at the 2nd and 5th positions in cyclic amines increases both the initial absorption rate and CO2 absorption capacity; similarly, substitution of alkyl groups and amines by side chains also increases the initial absorption rate and CO2 absorption capacity.

[0030] As a preferred technical solution of the present invention, the absorption treatment temperature is 30-40℃, such as 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0031] Preferably, the concentration of CO2 in the CO2-containing mixed gas is 10-20%, such as 10%, 12%, 14%, 16%, 18%, 20%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0032] As a preferred technical solution of the present invention, the heating desorption temperature is 90-120℃, such as 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0033] It should be noted that the absorption and desorption processes described in this invention are both carried out under normal pressure.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] (1) The mixed amine carbon capture absorbent of the present invention has the advantages of high CO2 absorption capacity and regeneration rate of the main absorbent and fast absorption rate and high removal rate of the auxiliary absorbent. Its CO2 absorption capacity is 1.16 mol CO2 / mol amine, the regeneration rate is >90%, and the regeneration process is simple, showing the excellent absorption and desorption performance of the absorbent.

[0036] (2) The regeneration energy consumption of the mixed amine carbon capture and absorbent of the present invention is 2.30 GJ·t. -1 Compared with the mixed amine carbon capture and absorbent reported in the literature, the mixed amine carbon capture and absorbent of the present invention has great application potential. The viscosity of the mixed amine carbon capture and absorbent before and after absorbing CO2 is low (<3.00cPa), and it still maintains good absorption and desorption performance after multiple cycles, showing excellent stability.

[0037] (3) The mixed amine carbon capture and absorbent of the present invention can capture CO2 from mixed gas efficiently and with low energy consumption, and has good application prospects. Attached Figure Description

[0038] Figure 1 This is a graph showing the CO2 load and regeneration rate of the mixed amine carbon capture and absorbent prepared in Example 10 of this invention after four cycles.

[0039] Figure 2 This is the VLE curve of the amine carbon trapping absorbent prepared in Example 10 of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0041] Example 1

[0042] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% tetramethylpropylenediamine, 10% N-methylpiperazine and 70% water;

[0043] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas. Specifically, it includes: weighing 150g of absorbent by mass percentage using an analytical balance, and controlling the temperature in a 40°C constant-temperature water bath. The absorbent is placed in a three-necked flask, and CO2 and N2 are mixed in a 15%:85% ratio to simulate flue gas using a mass flow controller, with a flow rate controlled at 1L / min. The CO2 concentration is confirmed using an infrared gas analyzer that has been preheated and zeroed with nitrogen. After the gas stabilizes, an absorption experiment is conducted. The mixed gas is sequentially absorbed, condensed, and dried by the mixed amine absorbent. The CO2 concentration is monitored using a gas analyzer. When the gas analyzer displays an outlet CO2 concentration of 15%, the absorbent is considered to have reached its saturated CO2 load, resulting in a CO2-saturated mixed amine carbon capture absorbent-rich solution.

[0044] The rich solution of the mixed amine carbon trapping absorbent is heated and desorbed. The oil bath is controlled at 120°C to condense the CO2 at the outlet. The outlet gas flow rate is monitored and recorded by a soap film flow meter. When the soap film flow meter shows that the outlet gas flow rate is <5mL / min, the desorption is considered to be complete, and a lean solution of the mixed amine carbon trapping absorbent is obtained.

[0045] Example 2

[0046] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 10% tetramethylpropylenediamine, 2% 2-methylpiperazine, 1% ethylenediaminetetraacetic acid (anti-degradation agent), and 87% water.

[0047] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas. Specifically, it includes: fully contacting the mixed amine carbon capture absorbent with a mixed gas containing CO2 for absorption treatment to obtain a CO2-saturated mixed amine carbon capture absorbent rich solution; and heating the mixed amine carbon capture absorbent rich solution for desorption to obtain a mixed amine carbon capture absorbent lean solution.

[0048] The absorption treatment temperature is 30°C; the CO2 concentration in the CO2-containing mixed gas is 15%; and the heating desorption temperature is 90°C.

[0049] Example 3

[0050] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 30% diethylenetriamine and tetramethylpropylenediamine, 15% N-aminoethylpiperazine, 1% sodium metavanadate (corrosion inhibitor), and 54% water.

[0051] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas. Specifically, it includes: fully contacting the mixed amine carbon capture absorbent with a mixed gas containing CO2 for absorption treatment to obtain a CO2-saturated mixed amine carbon capture absorbent rich solution; and heating the mixed amine carbon capture absorbent rich solution for desorption to obtain a mixed amine carbon capture absorbent lean solution.

[0052] The absorption treatment temperature is 35°C; the CO2 concentration in the CO2-containing mixed gas is 15%; and the heating desorption temperature is 100°C.

[0053] Example 4

[0054] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 25% hydroxyethyl ethylenediamine and 2-amino-2-methyl-1-propanol, 10% N-methylpiperazine, 3% polyethylene glycol (defoamer), and 62% water.

[0055] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas. Specifically, it includes: fully contacting the mixed amine carbon capture absorbent with a mixed gas containing CO2 for absorption treatment to obtain a CO2-saturated mixed amine carbon capture absorbent rich solution; and heating the mixed amine carbon capture absorbent rich solution for desorption to obtain a mixed amine carbon capture absorbent lean solution.

[0056] The absorption treatment temperature is 33°C; the CO2 concentration in the CO2-containing mixed gas is 15%; and the heating desorption temperature is 110°C.

[0057] Example 5

[0058] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% 2-amino-2-methyl-1-propanol, 10% N-methylpiperazine and 70% water;

[0059] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0060] Example 6

[0061] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% tetramethylpropylenediamine, 10% N-aminoethylpiperazine and 70% water;

[0062] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0063] Example 7

[0064] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% 2-amino-2-methyl-1-propanol, 10% N-aminoethylpiperazine and 70% water;

[0065] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0066] Example 8

[0067] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 24% tetramethylpropylenediamine, 6% N-methylpiperazine, and 70% water; that is, the mass ratio of the main absorbent to the co-absorbent is 4:1.

[0068] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0069] Example 9

[0070] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 25.7% tetramethylpropylenediamine, 4.3% N-methylpiperazine, and 70% water; that is, the mass ratio of the main absorbent to the co-absorbent is 6:1.

[0071] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0072] Example 10

[0073] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 26.7% tetramethylpropylenediamine, 3.3% N-methylpiperazine, and 70% water; that is, the mass ratio of the main absorbent to the co-absorbent is 8:1.

[0074] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0075] Example 11

[0076] This embodiment provides a mixed amine carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 27.3% tetramethylpropylenediamine, 2.7% N-methylpiperazine, and 70% water; that is, the mass ratio of the main absorbent to the co-absorbent is 10:1.

[0077] This embodiment also provides an application of the mixed amine carbon capture absorbent, which is used to capture CO2 from a mixed gas, and all other aspects are the same as in Example 1.

[0078] Comparative Example 1

[0079] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 30% ethanolamine and 70% water;

[0080] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0081] Comparative Example 2

[0082] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 30% tetramethylpropanediamine and 70% water;

[0083] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 10% N-methylpiperazine and 90% water;

[0086] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0087] Comparative Example 4

[0088] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 30% 2-amino-2-methyl-1-propanol and 70% water;

[0089] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0090] Comparative Example 5

[0091] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 10% N-aminoethylpiperazine and 90% water;

[0092] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0093] Comparative Example 6

[0094] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% ethanolamine, 10% N-methylpiperazine and 70% water;

[0095] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0096] Comparative Example 7

[0097] This comparative example provides a carbon capture absorbent for carbon dioxide capture, comprising the following components by mass percentage: 20% N-methylmonoethanolamine, 10% N-methylpiperazine and 70% water;

[0098] This comparative example also provides an application of the carbon capture absorbent, which is used to capture CO2 from a mixed gas, and is otherwise the same as in Example 1.

[0099] Performance testing

[0100] (1) CO2 absorption rate and CO2 loading of mixed amine carbon capture and absorbent

[0101] The CO2 load in the CO2-rich solution of the mixed amine carbon trap absorbent, saturated with CO2 obtained in Example 1, was determined by titration using a CO2 load testing device based on acid-base neutralization reaction. The analysis employed the principle of strong acid replacing weak acid; when hydrochloric acid solution was injected into the sample, CO2 was rapidly released from the sample solution. The specific experimental steps are as follows:

[0102] Place a clean rotor into the reaction flask, weigh a certain amount of the absorbent rich solution, add 50 mL of deionized water, and adjust the height before titration to make the liquid surface in the gas measuring tube parallel. Add 1 mol / L hydrochloric acid solution dropwise until excess, until the liquid level in the gas measuring tube no longer changes. Move the water level bottle up and down until the liquid level is parallel to the gas measuring tube, and record the gas measuring tube graduation, the total volume of hydrochloric acid consumed, and the volume of hydrochloric acid consumed to reach titration equilibrium. Based on the height difference between the initial graduation and the final graduation of the gas measuring tube, the volume of CO2 loaded in the absorbent sample can be calculated. Each sample should be repeated at least 3 times.

[0103] The CO2 absorption rate and CO2 loading of the rich solution were calculated using the following formulas:

[0104] CO2 absorption rate (×10) -5 mol / (kg∙s) ;

[0105] Where, q in q represents the CO2 flow rate in the inlet gas stream, in mL / min; out The CO2 flow rate in the outlet gas stream is expressed in mL / min; m a denoted as mass of the absorbent sample, in g; T represents the actual temperature, in K.

[0106] CO2 loading in rich solution (mol CO2 / mol amine) ;

[0107] Where, ΔV CO2 The volume of CO2 produced is L; n a denoted as the exact amount of the absorbent organic amine, in mol; ƒ is the gas volume correction factor when the experimental conditions are converted to standard conditions. , dimensionless quantity, P0 is standard atmospheric pressure, 101.325 kPa; P is the actual experimental pressure, kPa.

[0108] (2) CO2 desorption rate and lean solution CO2 loading of mixed amine carbon capture and absorbent

[0109] The calculation methods for CO2 desorption rate and CO2 loading of lean solution using mixed amine carbon capture and absorbent are similar to those for CO2 absorption rate and CO2 loading of rich solution, and will not be elaborated here.

[0110] (3) CO2 recycling capacity and regeneration rate of mixed amine carbon capture and absorbent

[0111] CO2 circulation capacity = CO2 loading rate of rich solution - CO2 loading rate of lean solution;

[0112] Regeneration rate = CO2 circulation capacity / rich liquid CO2 load.

[0113] (4) Cyclic performance of mixed amine carbon capture and absorbent

[0114] The cyclic performance of the absorbent was tested through multiple absorption and desorption experiments.

[0115] (5) Reaction heat and regeneration energy consumption of mixed amine carbon capture and absorbent

[0116] The equilibrium solubility of CO2 in the absorbent is measured using a gas-liquid equilibrium data acquisition (VLE) device, and the heat of reaction of the absorbent is calculated accordingly. The specific experimental steps are as follows:

[0117] First, the reactor is evacuated to remove air, and N2 is introduced to remove residual air while maintaining a constant gas phase partial pressure. Then, 100 mL of mixed amine-carbon absorbent is poured into the reactor, and a known volume of CO2 is stored in a CO2 storage tank. The temperature is adjusted to a stable state, and after gas-liquid equilibrium is reached, the initial pressure of the reactor is recorded. A fixed amount of CO2 is then introduced into the reactor to achieve a certain gas partial pressure. The heat of reaction of the absorbent can be calculated from the CO2 solubility data using the Gibbs-Helmholtz equation.

[0118] Heat of reaction (GJ / t CO2) ;

[0119] Regenerative energy consumption ;

[0120] in, is the heat of reaction of CO2 absorption by the absorbent, kJ / mol; M is the molecular weight of CO2, 44 g / mol; It is the specific heat capacity of the absorbent-rich liquid, obtained by differential scanning calorimetry using the sapphire method, kJ / (kg∙K); ΔT is the mass of the absorbent rich solution, in kg; ΔT is the temperature difference between the absorbent thermally lean rich solution and the absorbent solution, which is generally assumed to be 10K. It is the mass of CO2 absorbed, in grams; m H2O It is the content of water evaporated during the regeneration process (kg), which can be obtained by testing with a CO2 desorption device; It is the latent heat of vaporization of water, kJ / mol.

[0121] The viscosity of the absorbent and its rich solution was measured at 40°C using a Brookfield DV3T rotational viscometer (USA). The specific heat capacity of the absorbent was measured using a TA DSC25 thermogravimetric analyzer (USA) via the DSC sapphire method under a nitrogen atmosphere at temperatures ranging from 30 to 100°C.

[0122] The mixed amine carbon trapping and absorbent from Example 10 was subjected to multiple desorption experiments, and the CO2 loading of the lean and rich solutions was as follows: Figure 1 As shown; the CO2 equilibrium solubility of the mixed amine carbon trapping absorbent of Example 10 was measured using a VLE device at 40°C, 50°C, and 60°C, respectively, and the results are as follows. Figure 2 As shown.

[0123] The CO2 loading rate, maximum absorption rate, maximum desorption rate, and regeneration rate of the mixed amine carbon capture absorbents in Examples 1-11 and Comparative Examples 1-7 were calculated using the above calculation formula, and the results are shown in Table 1.

[0124] Table 1

[0125]

[0126] The test results show that:

[0127] (1) As can be seen from Table 1, the mixed amine carbon capture absorbents of Examples 1 to 7 have significantly better CO2 loading capacity, maximum absorption / desorption rate, and regeneration rate than Comparative Example 1, which is widely used in industry. Among them, Example 1 combines the advantages of high CO2 loading capacity and high regeneration rate of Comparative Example 2 as the main absorbent with the advantages of fast absorption rate and high removal rate of Comparative Example 3 as the auxiliary absorbent. Its CO2 loading capacity in the rich liquid reaches 1.07 mol CO2 / mol amine, and its maximum absorption rate reaches 57.98 × 10⁻⁶. -5mol / (kg∙s); Maximum desorption rate 275.90×10 -5 With a CO2 loading of 1.10 mol CO2 / mol amine and a regeneration rate as high as 92%, both significantly better than those of Comparative Example 1, a commonly used industrial absorbent, it exhibits excellent absorption and desorption performance. Furthermore, Example 6 showed the highest CO2 loading in its rich solution, reaching 1.10 mol CO2 / mol amine, but its highest absorption rate was only 46.89 × 10⁻⁶ mol / (kg∙s). - 5 The desorption rate was the lowest among the seven examples, at mol / (kg∙s); the highest desorption rate was second only to Example 1, at 248.89 × 10⁻⁶. -5 The regeneration rate was 87%, slightly lower than that of Example 1, and it showed good absorption and desorption performance, second only to Example 1.

[0128] (2) Based on Example 1, which exhibited the best absorption and desorption performance, the mixed amine carbon capture absorbent was further optimized by adjusting the ratio of different components. The ratios of the main absorbent to the co-absorbent in Examples 9-11 were 4:1, 6:1, 8:1, and 10:1, respectively. As shown in Table 1, the CO2 loading, maximum absorption / desorption rate, and regeneration rate of Examples 1 and 9-11 were all superior to those of Comparative Example 1. Furthermore, increasing the ratio of the main absorbent to the co-absorbent led to an upward trend in the CO2 loading of the absorbent in the rich solution. Among them, Example 11 had the highest CO2 loading in the rich solution, reaching 1.17 mol CO2 / mol amine, and its maximum absorption rate and maximum desorption rate were second only to Example 1, at 52.43 × 10⁻⁶. -5 mol / (kg∙s), 389.84×10 -5 The CO2 loading of Example 10 was 1.16 mol CO2 / mol amine, second only to Example 1, with a regeneration rate of 92%, and its highest absorption rate was 52.43 × 10⁻⁶ mol / (kg∙s). -5 mol / (kg∙s), with a maximum desorption rate of 558.36 × 10⁻⁶. -5 The regeneration rate was highest at mol / (kg∙s), which was most prominent in the examples, reaching 92%. Examples 10 and 11 both demonstrated excellent absorption and desorption performance, showing promising potential for practical applications.

[0129] (3) The mixed amine carbon capture and absorbent in Example 10 was subjected to multiple absorption and desorption experiments. The CO2 loading of the lean and rich liquids was as follows: Figure 1As shown in the figure, the absorption and desorption performance of the absorbent did not change significantly after multiple cycles, demonstrating excellent cycling performance. Furthermore, the viscosities of the purified absorbent solution and the rich solution were 2.72 cPa and 2.40 cPa, respectively. These low viscosity values ​​and minimal change before and after absorption are beneficial for practical applications.

[0130] The CO2 equilibrium solubility of the mixed amine carbon trapping absorbent in Example 10 was measured using a VLE device at 40°C, 50°C, and 60°C, respectively. The results are as follows: Figure 2 As shown, the heat of reaction and regeneration energy consumption of the absorbent were calculated based on the results. The heat of reaction of the mixed amine carbon trap absorbent in Example 10 was 1.36 GJ·t. -1 CO2 regeneration energy consumption is 2.30 GJ·t -1 CO2, far below 30% MEA, is 1.89 GJ·t. -1 The heat of reaction of CO2 is 3.95 GJ·t. -1 The energy consumption of CO2 regeneration is beneficial to reducing operating costs and demonstrates its broad application prospects.

[0131] (4) As can be seen from Example 1 and Comparative Examples 6-7, the present invention can improve the absorption rate and regeneration rate of mixed amine carbon capture absorbent by selecting the type of main absorbent, preferably an organic amine with multiple amino sites and a long carbon chain between them.

[0132] In summary, this invention provides a mixed amine carbon capture absorbent for carbon dioxide capture and its application. This mixed amine carbon capture absorbent combines the advantages of a primary absorbent (high CO2 absorption capacity and regeneration rate) with that of a secondary absorbent (fast absorption rate and high removal rate). Its CO2 absorption capacity is 1.16 mol CO2 / mol amine, its regeneration rate is >90%, and the regeneration process is simple, demonstrating the absorbent's excellent absorption and desorption performance. The regeneration energy consumption is 2.30 GJ·t. -1 Compared with the mixed amine carbon capture and absorbent reported in the literature, this method has great application potential for CO2. It has low viscosity (<3.00 cPa) before and after CO2 absorption, and maintains good absorption and desorption performance after multiple cycles, showing excellent stability. It can achieve efficient and low-energy capture of CO2 from mixed gases, and has good application prospects.

[0133] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A mixed amine carbon capture and absorbent for carbon dioxide capture, characterized in that, It includes the following components by mass percentage: 10-30% main absorbent, 2-15% co-absorbent, 0-5% additives, and the balance being water; The main absorbent comprises a polyamine and / or a sterically hindered amine; the polyamine has 2-4 amino groups; the amino groups of the polyamine include any one or a combination of at least two of primary, secondary, and tertiary amino groups; a carbon chain exists between the amino sites of the polyamine; the carbon chain has ≥2 carbon atoms; The absorption aid comprises cyclic amines with side chains.

2. The mixed amine carbon capture and absorbent according to claim 1, characterized in that, The polyamine includes any one or a combination of at least two of diethylenetriamine, triethylenediamine, hydroxyethylethylenediamine, tetraethylenepentamine, and tetramethylpropanediamine, preferably tetramethylpropanediamine; Preferably, the sterically hindered amine comprises 2-amino-2-methyl-1-propanol or 2-amino-2-methyl-1,3-propanediol.

3. The mixed amine carbon capture and absorbent according to claim 1 or 2, characterized in that, The absorption aid includes any one of N-methylpiperazine, 2-methylpiperazine or N-aminoethylpiperazine, preferably N-methylpiperazine; Preferably, the total amine concentration of the mixed amine carbon trapping and absorbing agent is 10-50%; Preferably, the mass ratio of the primary absorbent to the co-absorbent is 2:1 to 10:

1.

4. The mixed amine carbon capture and absorbent according to any one of claims 1-3, characterized in that, The additives include any one or a combination of at least two of the following: anti-degradation agents, corrosion inhibitors, or defoamers.

5. The mixed amine carbon capture and absorbent according to any one of claims 1-4, characterized in that, The anti-degradation agent includes any one or a combination of at least two of ethylenediaminetetraacetic acid, sodium potassium tartrate, or hydroquinone.

6. The mixed amine carbon capture and absorbent according to any one of claims 1-5, characterized in that, The corrosion inhibitor includes any one of sodium sulfite, sodium vanadate, sodium metavanadate, or sodium thiosulfate.

7. The mixed amine carbon capture and absorbent according to any one of claims 1-6, characterized in that, The defoamer includes any one of polydimethylsiloxane, polyethylene glycol, or polyether.

8. The application of a mixed amine carbon capture and absorbent as described in any one of claims 1-7, characterized in that, The mixed amine carbon capture absorbent is used to capture CO2 from a mixed gas, specifically by: fully contacting the mixed amine carbon capture absorbent with a mixed gas containing CO2 for absorption treatment to obtain a mixed amine carbon capture absorbent rich solution saturated with CO2. The rich solution of the mixed amine carbon trapping absorbent is heated and desorbed to obtain a poor solution of the mixed amine carbon trapping absorbent.

9. The application according to claim 8, characterized in that, The absorption treatment temperature is 30-40℃; the CO2 concentration in the CO2-containing mixed gas is 10-20%.

10. The application according to claim 8 or 9, characterized in that, The temperature for heating and desorption is 90-120℃.

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