Polyamine composite absorbent for capturing co 2, and regeneration method therefor

Abstract

The present application relates to the technical fields of resource environment and chemical engineering. Disclosed are a polyamine composite absorbent for capturing CO2, and a regeneration method therefor. The polyamine composite absorbent comprises: tetraaza-adamantane and a derivative thereof, an auxiliary and an organic solvent, wherein the tetraaza-adamantane and the derivative thereof contain an active amino. In the present application, an active amino is introduced into tetraaza-adamantane, and the selectivity and absorption efficiency for CO2 are improved by means of a steric hindrance effect, such that the reaction is more reversible and more thermodynamically advantageous. Thus, the absorption and desorption of CO2 can be achieved at relatively low temperatures, the overall energy consumption is reduced, and the cycle efficiency of the polyamine composite absorbent is improved.

Description

Polyamine composite absorbent for capturing CO2 and its regeneration method

[0001] This application claims priority to Chinese Patent Application No. 202411560600.3, filed on November 4, 2024, entitled "Polyamine Composite Absorbent for CO2 Capture and Regeneration Method Thereof", the entire contents of which are incorporated herein by reference. Technical Field

[0002] The embodiments of this application relate to, but are not limited to, the fields of resources and environment and chemical technology, and more specifically, to a polyamine composite absorbent for capturing CO2 and a method for regenerating it. Background Technology

[0003] Flue gas from coal-fired power plants, natural gas, refinery gas, cement plant gas, and nitrogen fertilizer plant gas all contain varying amounts of CO2. Taking flue gas from coal-fired power plants as an example, it is a mixture of solid particles, liquids, and gases containing multiple components. Its main components are nitrogen, carbon dioxide, incompletely burned oxygen, nitrogen oxides, and sulfides. Nitrogen oxides and sulfides are generally considered hazardous substances, while carbon dioxide can not only be effectively utilized as a raw material in chemical production but can also be collected and stored using advanced capture technologies to reduce its environmental impact.

[0004] Currently, carbon dioxide capture is typically achieved through chemical absorption, particularly using methyldiethanolamine (MDEA) solution as the absorbent. Specifically, when MDEA solution comes into contact with a CO2-containing gas, the CO2 dissolves in the solution and reacts chemically with MDEA to form reversible bicarbonates or carbonates. This reaction transfers CO2 from the gas phase to the liquid phase, thus purifying the gas and capturing the CO2. However, this method still requires significant energy consumption to achieve CO2 desorption. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] The purpose of this application is to provide a polyamine composite absorbent for capturing CO2 and a method for regenerating it, so as to achieve the effect of CO2 desorption with low energy consumption.

[0007] In a first aspect, this application provides a polyamine composite absorbent, which includes: tetraazaadamantane and its derivatives, an auxiliary agent and an organic solvent, wherein the tetraazaadamantane and its derivatives contain active amine groups.

[0008] In one optional embodiment, the content of tetraazaadamantane and its derivatives is 20 wt% to 79 wt%, the content of the auxiliaries is 0.01 wt% to 5 wt%, and the content of the organic solvent is 20 wt% to 75 wt%.

[0009] In an optional embodiment, the tetraazaadamantane and its derivatives are selected from one of the following general structural formulas, or a mixture of multiple formulas in any proportion:

[0010] In one alternative embodiment, the additive is selected from one or more of defoamers, antioxidants, and corrosion inhibitors.

[0011] In one optional embodiment, the defoamer is selected from one or more of polysiloxanes, fluorinated polysiloxanes, polyether-modified polysiloxanes, and polyoxyethylene ethers in any proportion; the antioxidant is selected from one or more of hindered phenolic antioxidants, aromatic amine antioxidants, and ascorbic acid in any proportion; and the corrosion inhibitor is selected from one or more of organic imidazoline, pyridine quaternary ammonium salts, inorganic nitrites, tungstates, molybdates, and vanadates in any proportion.

[0012] In one alternative embodiment, the organic solvent is selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion, or an aqueous solution selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion.

[0013] Secondly, this application provides a method for regenerating a polyamine composite absorbent, the method comprising:

[0014] The prepared raw gas, after being treated by the flue gas bypass system, is input to the bottom of the absorption tower which is operating under the first set conditions. The first set conditions include temperature and pressure, wherein the temperature range is 40℃~60℃ and the pressure range is 0.1MPa~10MPa.

[0015] The target composite absorbent is fed to the top of the absorption tower, and the target composite absorbent forms a countercurrent contact with the raw gas to obtain a rich liquid. The rich liquid is the target composite absorbent after absorbing CO2, and the target composite absorbent is the polyamine composite absorbent described in the first aspect and / or various possible embodiments of the first aspect.

[0016] The rich liquor is preheated by exchanging heat with the lean liquor flowing out from the bottom of the regeneration tower through a heat exchanger. The lean liquor is the target composite absorbent after desorbing CO2.

[0017] The preheated rich solution is fed to the top of the regeneration tower, which is operating under the second set conditions, to obtain the regenerated target composite absorbent. The regenerated target composite absorbent is a lean solution. The second set conditions include temperature and pressure. The temperature range is 90℃~130℃, and the pressure range is 0.1MPa~0.4MPa.

[0018] In one optional embodiment, the target composite absorbent is a diluted solution of a polyamine composite absorbent.

[0019] In one optional embodiment, the mass concentration of the polyamine complex absorbent in the diluent is 20% to 79%.

[0020] In one optional embodiment, the volume ratio of the polyamine composite absorbent to CO2 in the feed gas is 100:(0.1-80).

[0021] Thirdly, this application provides a regeneration method for a polyamine composite absorbent, the regeneration device comprising: a flue gas bypass system, an absorption tower, a regeneration tower, a heat exchanger, and a reboiler;

[0022] Flue gas bypass system is used to process the prepared raw gas;

[0023] An absorption tower is used to form a countercurrent contact between the raw gas flowing from bottom to top and the polyamine composite absorbent flowing from top to bottom of the absorption tower, to obtain decarbonized raw gas and rich liquid. The rich liquid is the polyamine composite absorbent after absorbing CO2. The polyamine composite absorbent is the polyamine composite absorbent described in the first aspect and / or various possible embodiments of the first aspect, or a diluted solution of the polyamine composite absorbent described in the first aspect and / or various possible embodiments of the first aspect, wherein the mass concentration of the polyamine composite absorbent in the diluted solution is 20-79%.

[0024] A heat exchanger is used to exchange heat between the rich solution and the lean solution flowing out from the bottom of the regeneration tower in order to preheat the rich solution.

[0025] A reboiler is used to provide heat to the regeneration tower;

[0026] The regeneration tower is used to obtain the desorbed CO2 and the regenerated polyamine composite absorbent from the preheated rich liquid.

[0027] This application provides a polyamine composite absorbent for capturing CO2 and a method for its regeneration. The polyamine composite absorbent comprises tetraazaadamantane and its derivatives, an auxiliary agent, and an organic solvent. The tetraazaadamantane and its derivatives contain active amine groups. This application introduces active amine groups into tetraazaadamantane, improving the selectivity and absorption efficiency of CO2 through steric hindrance, making the reaction more reversible and thermodynamically advantageous. This allows for CO2 absorption and desorption at lower temperatures, reducing overall energy consumption and improving the recycling efficiency of the polyamine composite absorbent.

[0028] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] Figure 1 is a schematic diagram of the structure of a regeneration device for a polyamine composite absorbent provided in an embodiment of this application.

[0031] Explanation of reference numerals in the attached diagram: 1: Absorber; 2: Regeneration tower; 3: Lean liquor storage tank; 4: Heat exchanger; 5: Lean liquor pump; 6: Rich liquor storage tank; 7: Reboiler; 8: Rich liquor pump.

[0032] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments.

[0033] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0036] Whether it's reducing carbon emissions from coal-fired power plants or improving oil recovery (ROE) through CO2 injection in oil and gas field development, carbon dioxide capture and storage is a critical issue that urgently needs to be addressed.

[0037] Among numerous CO2 capture technologies, chemical absorption, especially organic amine-based absorption, has been widely used in industry. Organic amine-based absorption uses CO2 as an acid to induce a reversible acid-base neutralization reaction with the organic amine-based absorbent. At relatively low temperatures, such as 40℃–80℃, an absorption-neutralization chemical reaction occurs, capturing CO2. Under high-temperature conditions, such as 100℃–130℃, the absorbent that has absorbed a large amount of CO2 undergoes a decomposition reaction, releasing CO2. The organic amine-based absorbent is then regenerated and returned to the absorption step, in a repeated cycle. The traditional organic amine base absorption method initially used an aqueous solution of monoethanolamine (MEA) as the absorbent. Later, it was developed into methyldiethanolamine (MDEA). In particular, MDEA-formulated absorbents (such as MDEA + activator diethanolamine (DEA)) have overcome the shortcomings of MEA as a single alcohol amine absorbent. In terms of energy saving, consumption reduction and equipment corrosion control, it has rapidly developed into the main solvent absorption method.

[0038] The development of amine absorbents more suitable for different operating conditions has been ongoing, and soon hindered amines with steric hindrance effects were developed for use in decarbonization. Stericly hindered amines are effective because the nitrogen atom has at least one dissociable hydrogen atom, and the group attached to the nitrogen atom is a non-linear carbon chain, such as a tert-butyl group. Steric hindered amines generate significant steric hindrance, resulting in low molar heat of reaction when the amine absorbent reacts with CO2. The formed carbamate is unstable, but precisely because of this characteristic, the carbamate also readily removes CO2. The desorption of CO2 by the amine-rich solution can proceed at lower temperatures, preventing carbamate accumulation, avoiding system corrosion, and significantly reducing operating energy consumption. However, existing sterically hindered amines suffer from limited sources, poor selectivity, and generally weak steric hindrance effects, and are constrained by cost, failing to meet production needs.

[0039] Existing alkanolamine absorbents, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N-methyl-diethanolamine (MDEA), piperazine, triazine, diisopropanolamine (DIPA), and 2-amino-2-methyl-1-propanol (AMP), have an N / C atomic ratio not exceeding 0.5, resulting in a CO2 absorption capacity of 0.5–0.8 mol CO2 / 1 mol absorbent. Polyethylene polyamines, such as diethylenetriamine, triethylenetetraamine, and tetraethylenepentamine, have a higher N / C atomic ratio, leading to a CO2 absorption capacity of up to 1.2 mol CO2 / 1 mol absorbent. Therefore, increasing the N / C atomic ratio of alkanolamine absorbents to improve their absorption capacity is a key direction for developing novel alkanolamine absorbents.

[0040] To address the aforementioned problems, this application provides a polyamine composite absorbent comprising: tetraazaadamantane and its derivatives, an additive, and an organic solvent. The tetraazaadamantane and its derivatives contain active amine groups. The tetraazaadamantane and its derivatives possess inherent active amines, enabling self-activation and increasing the absorption rate and capacity, thereby achieving CO2 desorption with lower energy consumption.

[0041] This application provides a polyamine composite absorbent, comprising: tetraazaadamantane and its derivatives, an auxiliary agent, and an organic solvent. The tetraazaadamantane and its derivatives contain active amine groups. It is understood that the polyamine composite absorbent of this application comprises these three substances: tetraazaadamantane and its derivatives, an auxiliary agent, and an organic solvent. The tetraazaadamantane and its derivatives contain active amine groups, which can chemically react with CO2 molecules to form compounds such as ammonium bicarbonate or carbamates. This chemical adsorption process is typically reversible; CO2 can be released by heating or reducing pressure, regenerating the active amine groups. This reversibility allows the tetraazaadamantane derivatives to effectively capture and release CO2 in multiple cycles.

[0042] This application's embodiments introduce active amine groups into tetraazaadamantane, improving the selectivity and absorption efficiency of CO2 through steric hindrance, making the reaction more reversible and thermodynamically advantageous. This allows for CO2 absorption and desorption at lower temperatures, reducing overall energy consumption and improving the cycle efficiency of the polyamine composite absorbent.

[0043] In some embodiments, tetraazaadamantane and its derivatives are selected from one of the following general structural formulas, or a mixture of multiple formulas in any proportion:

[0044] It is understandable that tetraazaadadamantane and its derivatives contain active amine (-NH) groups. These active amine groups ensure rapid neutralization with CO2, resulting in a fast absorption rate and good steric hindrance, leading to a low molar heat of reaction with CO2 and allowing CO2 desorption in the absorbent solution to occur at a lower temperature. Furthermore, the presence of active amines in tetraazaadadamantane and its derivatives enables self-activation, further increasing the absorption rate and capacity. Optionally, tetraazaadadamantane and its derivatives may also contain four tertiary amine groups. Group.

[0045] Optionally, tetraazaadadamane has an N / C atomic ratio of 0.67, comparable to diethylenetriamine, the polyethylenepolyamine compound with the highest N / C ratio. Aminotetraazaadadamane has an N / C atomic ratio of 0.83, the highest among alkanolamine absorbents. Each nitrogen atom is a reaction site with CO2, resulting in a high carbon capacity, which significantly reduces the volume of the regeneration solution and further reduces regeneration energy consumption.

[0046] In some embodiments, the content of tetraazaadamantane and its derivatives is 20 wt% to 79 wt%, the content of the additives is 0.01 wt% to 5 wt%, and the content of the organic solvent is 20 wt% to 75 wt%. Excessive content of tetraazaadamantane and its derivatives can lead to saturation of the adsorbent surface, thereby reducing its CO2 capture capacity; insufficient content can result in ineffective CO2 capture, leading to reduced efficiency. Excessive content of the additives can alter the physical properties of the adsorbent or solvent, such as changes in viscosity or density, thus affecting mass and heat transfer efficiency; insufficient content of the additives can lead to a decrease in reaction rate and a prolonged capture time. Excessive content of the organic solvent can reduce mass transfer efficiency because the contact area between the organic solvent and the gas is relatively reduced; insufficient content of the organic solvent can lead to incomplete CO2 capture.

[0047] In some embodiments, the additive is selected from one or more of defoamers, antioxidants, and corrosion inhibitors.

[0048] Defoamers are chemical additives used to reduce or eliminate foam in liquids. Appropriate selection of defoamer types is beneficial for effectively controlling foam problems and improving production efficiency. For example, defoamers are selected from one or more of polysiloxanes, fluorinated polysiloxanes, polyether-modified polysiloxanes, and polyoxyethylene ethers, in any proportion as a mixture.

[0049] Antioxidants are compounds that can inhibit or delay the oxidation process. They protect materials by neutralizing free radicals or preventing oxidation chain reactions. Appropriate selection of antioxidants is beneficial for effectively preventing oxidative damage. For example, antioxidants are selected from one or more of hindered phenolic antioxidants, aromatic amine antioxidants, and ascorbic acid, in any proportion.

[0050] Corrosion inhibitors (also known as corrosion suppressants) are a class of chemical substances used to reduce or prevent corrosion of metallic materials when they come into contact with corrosive environments. Proper selection of corrosion inhibitors can effectively extend the service life of metal equipment and structures, reduce maintenance costs, and improve safety and reliability.

[0051] In some embodiments, the corrosion inhibitor is selected from one or more of organic imidazoline, pyridine quaternary ammonium salt, inorganic nitrite, tungstate, molybdate, and vanadate in any proportion.

[0052] In some embodiments, the organic solvent is selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion, or an aqueous solution selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion. The organic solvent is chosen from mixtures of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether, or aqueous solutions thereof, for the following reasons: these substances provide excellent solubility and perform well in handling complex chemical structures; secondly, these substances have high chemical stability and remain stable under harsh conditions, reducing the occurrence of side reactions; and thirdly, these substances have a wide boiling point range, facilitating the optimization of reaction conditions. Alternatively, by adjusting the mixing ratio of these substances, specific solubility and reactivity can be achieved to meet diverse industrial needs.

[0053] Optionally, embodiments of this application also provide a method for regenerating a polyamine composite absorbent. The regeneration method includes: inputting a prepared feed gas, treated by a flue gas bypass system, into the bottom of an absorption tower operating under first set conditions, the first set conditions including temperature and pressure, wherein the temperature range is 40℃~60℃ and the pressure range is 0.1MPa~10MPa; inputting a target composite absorbent into the top of the absorption tower, whereby the target composite absorbent and the feed gas form a countercurrent contact to obtain a rich liquid, wherein the rich liquid is the target composite absorbent after CO2 absorption. The target composite absorbent is the polyamine composite absorbent described in the previous embodiments. A heat exchanger is used to preheat the rich solution and the lean solution flowing from the bottom of the regeneration tower, which is the target composite absorbent after CO2 desorption. The preheated rich solution is then fed to the top of the regeneration tower operating under second set conditions to obtain the regenerated target composite absorbent, which is the lean solution. The second set conditions include temperature and pressure, with the temperature ranging from 90°C to 130°C and the pressure ranging from 0.1 MPa to 0.4 MPa. Optionally, the regenerated target composite absorbent flows out from the bottom of the regeneration tower, exchanges heat with the rich solution entering the regeneration tower via a heat exchanger, and is pumped back into the top of the absorbent tower when cooled to the set temperature, forming a closed-loop cycle to regenerate the polyamine composite absorbent.

[0054] In some embodiments, the target composite absorbent may also be a diluted solution of the polyamine composite absorbent described in the preceding embodiments. The mass concentration of the polyamine composite absorbent in the diluted solution is 20% to 79%. Using a diluted solution of the polyamine composite absorbent as the target composite absorbent can reduce the corrosiveness of the target composite absorbent, minimize damage to the device materials, and extend the service life of the device.

[0055] Optionally, the volume ratio of the aforementioned polyamine composite absorbent to CO2 in the feed gas is 100:(0.1–80). A volume ratio that is too low means the amount of polyamine composite absorbent is insufficient to fully react with the CO2 in the feed gas, resulting in a chemical equilibrium bias towards unreacted CO2. This indicates that the CO2 absorption reaction is incomplete, leading to reduced absorption efficiency. A volume ratio that is too high means the amount of polyamine composite absorbent is excessive. While an excess of polyamine composite absorbent can help drive the reaction towards the products, excessive polyamine composite absorbent may require more energy to break chemical bonds and release absorbed CO2 during regeneration. Therefore, by adjusting the volume ratio, it is possible to ensure that the concentration of the polyamine composite absorbent is sufficient to effectively absorb CO2, improve absorption efficiency, and reduce unabsorbed CO2 emissions. An appropriate volume ratio helps optimize the amount of polyamine composite absorbent used, thereby reducing energy consumption during regeneration and improving the overall economic efficiency of the process.

[0056] This application also provides a regeneration device for a polyamine composite absorbent. Figure 1 is a schematic diagram of the structure of a regeneration device for a polyamine composite absorbent provided in this application. As shown in Figure 1, the regeneration device includes: a flue gas bypass system, an absorption tower, a regeneration tower, a heat exchanger, a reboiler, a rich liquid storage tank, a rich liquid pump, a lean liquid storage tank, and a lean liquid pump.

[0057] The flue gas bypass system is used to process the prepared raw gas, which contains 10% CO2.

[0058] An absorption tower is used to form a countercurrent contact between the raw gas flowing from bottom to top and the polyamine composite absorbent flowing from top to bottom of the absorption tower, to obtain decarbonized raw gas and rich liquid. The rich liquid is the polyamine composite absorbent after absorbing CO2. The polyamine composite absorbent is the polyamine composite absorbent described in the previous embodiment, or a diluted solution of the polyamine composite absorbent described in the previous embodiment. The mass concentration of the polyamine composite absorbent in the diluted solution is 20-79%.

[0059] A heat exchanger is used to exchange heat between the rich solution and the lean solution flowing out from the bottom of the regeneration tower in order to preheat the rich solution.

[0060] A reboiler is used to provide heat to the regeneration tower;

[0061] The regeneration tower is used to obtain the desorbed CO2 and the regenerated polyamine composite absorbent from the preheated rich liquid.

[0062] A flooded liquid storage device is used to temporarily store flooded liquid.

[0063] A rich solution pump is used to transport rich solution from a rich solution storage tank to a regeneration tower;

[0064] An empty solution reservoir is used to temporarily store empty solution.

[0065] A lean solution pump is used to transfer lean solution from the lean solution storage tank back to the absorption tower.

[0066] It should be noted that feedstock gas includes one or more of the following: flue gas from coal-fired power plants, natural gas, refinery gas, cement plant gas, liquefied petroleum gas, and syngas from fertilizer plants. Carbon dioxide in flue gas from coal-fired power plants includes N2, O2, and CO2.

[0067] Optionally, this application also discloses an application of a polyamine composite absorbent in the apparatus of FIG1, wherein the polyamine composite absorbent is used directly or diluted with a solvent for CO2 capture, the polyamine composite absorbent that has absorbed CO2 from flue gas from a coal-fired power plant is regenerated, and the regenerated polyamine composite absorbent is used again for CO2 capture.

[0068] The regeneration method of the polyamine composite absorbent provided in this application will be further described below with reference to specific embodiments.

[0069] Unless otherwise specified, the experimental methods used in the following embodiments can be conventional methods in the art.

[0070] In the following embodiments, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0071] Experiment 1

[0072] By using different absorbents, a treatment capacity of 1×10⁻⁶ can be captured. 6 m 3 The CO2 in the flue gas of a coal-fired power plant was collected under the following conditions: absorbent solution circulation rate maintained at 10 t / h, absorption temperature at 43℃, and regeneration temperature at 108℃. After 720 hours of operation, the operational performance of different absorbents was analyzed and checked, as shown in Table 1. The method for capturing CO2 in the flue gas of a coal-fired power plant using absorbents is described in the previous examples.

[0073] Table 1: Decarbonization effect of different absorbents

[0074] The specific formulation of composite absorbent 1 in Example 1 is as follows: 30% aminotetraazadamane; 0.1% polysiloxane; 0.1% organic imidazoline; 0.1% antioxidant; and 30% sulfolane.

[0075] The specific formulation of the composite absorbent 2 in Example 2 is as follows: 35% aminotetraazadamane; 0.1% polysiloxane; 0.1% organic imidazoline; 0.1% antioxidant; and 30% sulfolane.

[0076] The specific formulation of the composite absorbent 3 in Example 3 is as follows: 35% aminomethyltetraazadamane; 0.1% polysiloxane; 0.1% organic imidazoline; 0.1% antioxidant; and 25% piperazine.

[0077] The specific formulation of the composite absorbent 4 in Example 4 is as follows: 40% aminomethyltetraazadamane; 0.1% polysiloxane; 0.1% molybdate; 0.1% antioxidant; and 30% ethylene glycol dimethyl ether.

[0078] The specific formulation of the composite absorbent 5 in Example 5 is as follows: 40% aminomethylhydroxytetraazadamane; 0.1% polysiloxane; 0.1% molybdate; 0.1% antioxidant; and 35% piperazine.

[0079] The specific formulation of the composite absorbent 6 in Example 6 is as follows: 30% aminomethylhydroxytetraazadamane; 0.1% polysiloxane; 0.1% molybdate; 0.1% antioxidant; and 40% ethylene glycol monoethyl ether.

[0080] The specific formulation of the composite absorbent 7 in Example 7 is as follows: 40% aminotetraazadamane; 0.1% polysiloxane; 0.1% pyridine quaternary ammonium salt; 0.1% antioxidant; and 40% sulfolane.

[0081] The results show that the composite absorbent of the present invention has better decarbonization performance than the traditional MDEA absorbent.

[0082] Experiment 2:

[0083] This experiment evaluated the corrosion of equipment by polyamine composite absorbents. Q235 steel sheets were used. After degreasing, polishing, drying, and constant weighting, the steel sheets were weighed and immersed in an alcohol amine absorbent solution at 100℃. A mixed gas (10% CO2) was passed into the solution at 150 mL / min for 48 hours. After that, the Q235 steel sheets were removed, corrosion products on the surface of the steel sheets were removed, dried, and weighed. The weight loss of the sheets was measured. The corrosion of carbon steel by solutions with different compositions is shown in Table 2.

[0084] Table 2 Comparison of corrosion rates

[0085] The data in Table 2 show that the corrosivity is reduced when using the composite absorbent of the present invention.

[0086] Experiment 3:

[0087] This experiment evaluated the polyamine composite absorbent for a single-treatment capacity of 3.6 × 10⁻⁶. 5 m 3 CO2 capture from flue gas of a coal-fired power plant, with CO2 accounting for 10% of the inlet gas composition, absorbent solution circulation rate of 4.2 t / h, absorption temperature of 41℃, and regeneration temperature of 103℃, after 760 hours of operation, the accumulation of stable salts was analyzed and determined in accordance with standard SY / T7001. The accumulation of stable salts in solutions with different compositions is shown in Table 3.

[0088] Table 3 Comparison of the accumulation of stable salts

[0089] The data in Table 3 show that the stability of the salt accumulation is greatly improved when using the polyamine composite absorbent of the present invention.

[0090] Experiment 4:

[0091] This experiment used different absorbents to capture a sample with a processing capacity of 1.2 × 10⁻⁶. 5 m 3The carbon capacity of CO2 in the flue gas of a coal-fired power plant was determined by measuring the amount of CO2 absorbed by the absorbent during the absorption and regeneration cycles. The specific comparison results are shown in Table 4. CO2 accounts for 8% of the inlet gas composition. The absorbent solution circulation rate is 0.85 t / h. The absorption temperature is 40℃ and the regeneration temperature is 102℃.

[0092] Table 4 Comparison of Carbon Capacity

[0093] The data in Table 4 show that the carbon capacity is greatly improved when using the composite absorbent of the present invention.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0095] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A polyamine composite absorbent, said polyamine composite absorbent comprising: Tetraazaadamantane and its derivatives, auxiliaries and organic solvents, wherein the tetraazaadamantane and its derivatives contain active amine groups.

2. The polyamine composite absorbent according to claim 1, wherein the content of the tetraazadamane and its derivatives is 20wt% to 79wt%, the content of the auxiliary agent is 0.01wt% to 5wt%, and the content of the organic solvent is 20wt% to 75wt%.

3. The polyamine composite absorbent according to claim 1 or 2, wherein the tetraazadamane and its derivatives are selected from one of the following general structural formulas, or a mixture of multiple formulas in any proportion:

4. The polyamine composite absorbent according to claim 1 or 2, wherein the auxiliary agent is selected from one or more of defoamers, antioxidants, and corrosion inhibitors.

5. The polyamine composite absorbent according to claim 4, wherein the defoamer is selected from one or more of polysiloxanes, fluorinated polysiloxanes, polyether-modified polysiloxanes, and polyoxyethylene ethers in any proportion; the antioxidant is selected from one or more of hindered phenolic antioxidants, aromatic amine antioxidants, and ascorbic acid in any proportion; and the corrosion inhibitor is selected from one or more of organic imidazoline, pyridine quaternary ammonium salts, inorganic nitrites, tungstates, molybdates, and vanadates in any proportion.

6. The polyamine composite absorbent according to claim 1 or 2, wherein the organic solvent is selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion, or an aqueous solution selected from one or more of sulfolane, piperazine, triazine, polyethylene polyamine, ethylene glycol, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether in any proportion.

7. A method for regenerating a polyamine composite absorbent, comprising: The prepared raw gas, after being treated by the flue gas bypass system, is input to the bottom of the absorption tower which is operating under the first set conditions. The first set conditions include temperature and pressure, wherein the temperature range is 40℃~60℃ and the pressure range is 0.1MPa~10MPa. The target composite absorbent is fed to the top of the absorption tower, and the target composite absorbent forms a countercurrent contact with the raw gas to obtain a rich liquid, wherein the rich liquid is the target composite absorbent after absorbing CO2, and the target composite absorbent is the polyamine composite absorbent according to any one of claims 1 to 6. The rich liquid is preheated by exchanging heat with the lean liquid flowing out from the bottom of the regeneration tower through a heat exchanger. The lean liquid is the target composite absorbent after desorbing CO2. The preheated rich liquid is fed to the top of a regeneration tower operating under the second set conditions to obtain the regenerated target composite absorbent. The regenerated target composite absorbent is a lean liquid. The second set conditions include temperature and pressure. The temperature range is 90℃ to 130℃, and the pressure range is 0.1MPa to 0.4MPa.

8. The regeneration method according to claim 7, wherein the target composite absorbent is a diluted solution of the polyamine composite absorbent.

9. In the regeneration method according to claim 8, the mass concentration of the polyamine composite absorbent in the diluent is 20% to 79%.

10. The regeneration method according to any one of claims 7 to 9, wherein the volume ratio of the polyamine composite absorbent to CO2 in the feed gas is 100:(0.1 to 80).

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