An absorbent for capturing carbon dioxide and a production process thereof

Abstract

The present application relates to the technical field of carbon dioxide capture, and particularly relates to an absorbent for capturing carbon dioxide and a production process thereof.The absorbent comprises, by weight parts, 30-50 parts of a composite amine component, 5-15 parts of an activator, 3-10 parts of a phase separation promoter, 1-5 parts of modified silica, 2-8 parts of a regulating agent, 0.5-3 parts of an anti-degradation agent, 0.5-2 parts of a corrosion inhibitor, and 20-40 parts of water.The present application significantly improves the carbon dioxide absorption capacity, absorption rate and anti-oxidation degradation performance of the absorbent through the synergistic effect of the modified silica and the regulating agent.The organic polymer chains are grafted on the surface of the modified silica, thereby enhancing the compatibility with the amine solution and the mass transfer efficiency;the chitosan-based composite microspheres in the regulating agent load nano cerium oxide, thereby having the dual functions of anti-degradation and corrosion inhibition.The present application is suitable for the efficient capture of carbon dioxide in coal-fired flue gas, industrial tail gas and ship exhaust gas.

Description

Technical Field

[0001] This invention belongs to the technical field of carbon dioxide capture, specifically relating to an absorbent for capturing carbon dioxide and its production process. Background Technology

[0002] Chemical absorption is currently the most mature and widely used CO2 capture technology. Among them, organic amine absorption has been widely used in industry due to its advantages such as high absorption efficiency, good selectivity and mature technology.

[0003] Traditional organic amine absorbents, represented by 30% monoethanolamine (MEA) aqueous solutions, offer advantages such as rapid absorption rates, but suffer from technical problems including limited absorption capacity, high regeneration energy consumption, severe oxidative degradation, and strong corrosivity. Recent research on polyamine-compound absorbents and nano-enhanced absorbents has provided new solutions to these problems; however, existing technologies suffer from poor dispersion stability of nanoparticles, insufficient compatibility with amine solutions, and a lack of effective anti-degradation and corrosion-inhibiting functional components.

[0004] To address the aforementioned technical problems, this invention develops a CO2 absorbent with high absorption capacity, fast absorption rate, low regeneration energy consumption, and low corrosivity by designing a synergistic system of modified silica and an additive. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the purpose of this invention is to provide an absorbent for capturing carbon dioxide and its production process, so as to solve the problems mentioned in the background art.

[0006] The present invention solves the technical problem by adopting the following technical solution: This invention provides an absorbent for capturing carbon dioxide, the raw materials comprising, by weight: 30-50 parts of a complex amine component, 5-15 parts of an activator, 3-10 parts of a phase separation promoter, 1-5 parts of modified silica, 2-8 parts of a modifier, 0.5-3 parts of an anti-degradation agent, 0.5-2 parts of a corrosion inhibitor, and 20-40 parts of water.

[0007] The complex amine component is composed of N-(2-hydroxyethyl)ethylenediamine, diethylenetriamine and N-methyldiethanolamine in a weight ratio of (2-5):(1-3):(1-2).

[0008] The synergistic effect of the three amines: diethylenetriamine (DETA) provides high absorption capacity; N-(2-hydroxyethyl)ethylenediamine provides a rapid absorption rate and additional hydroxyl sites; and N-methyldiethanolamine (MDEA) provides low heat of reaction and easy desorption properties. The combination of these three amines forms a synergistic system of "high capacity - fast absorption - low energy consumption".

[0009] The modified silica is prepared by the following steps: a1) Add nano-silica to sufficient anhydrous ethanol and ultrasonically disperse for 30-45 min at an ultrasonic power of 300-400 W to obtain a silica dispersion. a2) Add 5-10% by weight of silane coupling agent KH550 to the silica dispersion and stir at 60-80℃ for 2-3 hours to obtain silane-modified silica. a3) Add 8-15% by weight of an organic grafting monomer, wherein the organic grafting monomer is glycidyl methacrylate or acrylamide, and simultaneously add 0.5-1% of the initiator benzoyl peroxide. Perform a polymerization grafting reaction at 70-85℃ for 3-5 hours. After the reaction is completed, filter, wash with ethanol, and dry to obtain modified silica.

[0010] In the modification of silica, the first step is silane modification: the amino group of the silane coupling agent KH550 reacts with the silanol groups on the surface of nano-silica, introducing amine functional groups onto the nanoparticle surface and providing reaction sites for subsequent graft polymerization. The second step is graft polymerization: glycidyl methacrylate (GMA) or acrylamide (AM), under the action of the initiator benzoyl peroxide (BPO), undergoes free radical polymerization with the double bonds on the surface of the silane-modified silica, grafting polymer chains onto the nanoparticle surface. The epoxy groups in GMA can undergo ring-opening reactions with amines, enhancing chemical compatibility with amine solutions; the amide groups in AM possess excellent hydrophilicity and hydrogen bond forming ability. The grafted polymer chains have a triple function: improving the dispersion stability of nanoparticles in amine solutions; increasing the gas-liquid contact area and enhancing mass transfer due to the flexibility of the polymer chains; and allowing the surface functional groups (epoxy and amide groups) to participate in carbon dioxide absorption reactions, increasing absorption capacity.

[0011] The nano-silica has a particle size of 20-80 nm and a specific surface area of ​​150-300 m². 2 / g.

[0012] The additive is prepared by the following steps: b1) Dissolve 3-8 parts of chitosan in 100-150 parts of acetic acid solution with a mass fraction of 1-3%, and stir until completely dissolved to obtain a chitosan solution; b2) Add 2-5 parts of polyvinyl alcohol, 1-3 parts of nano-cerium oxide and 0.5-2 parts of citric acid to the chitosan solution, and stir at 50-70℃ for 1-2 hours to obtain the composite modified solution; b3) Spray dry the composite modified liquid with an inlet temperature of 160-200℃ and an outlet temperature of 80-100℃ to obtain chitosan-based composite microspheres, which are the additives.

[0013] In the additives, chitosan, a natural cationic polysaccharide, possesses excellent film-forming properties, biocompatibility, and antibacterial activity. The abundant hydroxyl and amino groups on the chitosan molecular chain can form hydrogen bonds with components in the amine solution, enhancing the system's stability. Polyvinyl alcohol, acting as a film-forming aid and toughening agent, forms an interpenetrating network structure with chitosan, improving the mechanical properties and structural stability of the microspheres. Nano-cerium oxide exhibits excellent antioxidant properties and catalytic activity. 3+ / Ce 4+ The variable valence properties of cerium oxide enable it to effectively scavenge free radicals and inhibit the oxidative degradation of amines. Simultaneously, cerium oxide nanoparticles act as corrosion inhibitors, forming a protective film on metal surfaces to suppress corrosion. Citric acid, acting as a crosslinking and chelating agent, undergoes a crosslinking reaction with the amino groups of chitosan, enhancing the stability of the microsphere structure; it also chelates metal ions, inhibiting metal-catalyzed amine oxidation reactions. The chitosan-based composite microspheres possess four functions: serving as a carrier for nano-cerium oxide, achieving long-term anti-degradation effects; the amino groups of chitosan can participate in carbon dioxide absorption reactions; the porous structure of the microspheres increases the gas-liquid contact area; and the slow release of citric acid continuously chelates metal ions.

[0014] The chitosan has a degree of deacetylation ≥90% and a molecular weight of 50,000-200,000; the polyvinyl alcohol has a degree of alcoholysis 85-99% and a molecular weight of 5,000-20,000; the nano-cerium oxide has a particle size of 20-60 nm and a purity ≥99%.

[0015] The activator is at least one of piperazine, N-hydroxyethylpiperazine or aminoethylpiperazine; The phase separation promoter is at least one of sulfolane, n-propanol, isopropanol or dimethyl sulfoxide; The anti-degradation agent is at least one of sodium sulfite, potassium sulfite, ammonium sulfite, or ethylenediaminetetraacetic acid; The corrosion inhibitor is at least one of vanadate, molybdate, or benzotriazole; The present invention also provides a production process for an absorbent for capturing carbon dioxide, comprising the following steps: 1) Weigh out the following components by weight: amine complex, activator, phase separation promoter, modified silica, conditioning agent, anti-degradation agent, corrosion inhibitor, and water. 2) Add the complex amine components and water to the reaction vessel, and stir at 200-400 r / min for 10-20 min at 25-40℃ to obtain the amine mother liquor; 3) Add activator and phase separation promoter to the amine mother liquor, and continue stirring for 15-30 minutes to obtain a mixture; 4) Add the modified silica and the modifier to the mixture and ultrasonically disperse for 20-40 minutes to obtain the nanocomposite liquid; 5) Add anti-degradation agent and corrosion inhibitor to the nanocomposite liquid, and stir at 300-500 r / min for 20-40 min at 30-50℃ to obtain crude absorbent; 6) Filter the crude absorbent with a filter membrane pore size of 0.45-1.0 μm, and let the filtrate stand to defoam; 7) Sampling and testing are conducted. If the sample passes the test, it is then filled into a container to obtain the carbon dioxide capture absorbent.

[0016] Preferably, in step 4), the ultrasonic dispersion power is 300-500W, the ultrasonic frequency is 40-60kHz, and the temperature is controlled at 25-40℃.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The carbon dioxide capture absorbent of this invention uses modified silica through a two-step modification process: first, silane coupling modification with KH550, followed by graft polymerization with glycidyl methacrylate or acrylamide to introduce long polymer chains onto the surface of the nanoparticles. The grafted polymer chains not only improve the dispersion stability of the nanoparticles in amine solutions, but their surface epoxy or amide groups can also participate in the carbon dioxide absorption reaction, transforming the nanoparticles from inert fillers into active absorption-enhancing components. The additive of this invention uses chitosan as a matrix, loaded with cerium nanoparticles, and prepared into composite microspheres by spray drying. The variable valence properties (Ce) of cerium nanoparticles... 3+ / Ce 4+ This invention endows the microspheres with excellent free radical scavenging ability, effectively inhibiting the oxidative degradation of amines. The chelating effect of chitosan and citric acid further synergistically resists degradation. The addition of the additive reduces the oxidative degradation rate of the absorbent. Modified silica and the additive have a synergistic effect. The grafted polymer chains on the surface of modified silica and the chitosan molecular chains on the surface of the additive microspheres interact through hydrogen bonds to form a three-dimensional network structure, further enhancing the dispersion stability of nanoparticles and the mass transfer efficiency of the system. This invention achieves a balanced optimization of absorption capacity, absorption rate, and desorption efficiency through the synergistic compounding of composite amine components, activators, and phase separation promoters, and reduces regeneration energy consumption compared to traditional MEA processes. This invention is suitable for the efficient capture of carbon dioxide from coal-fired flue gas, industrial exhaust gas, and ship exhaust gas. Detailed Implementation

[0018] The present invention will be further described in detail below through specific implementation examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope of the appended claims.

[0019] Unless otherwise specified, all raw materials and reagents used in this invention are from the conventional market.

[0020] The nano-silica used in this invention has a particle size of 20-80 nm and a specific surface area of ​​150-300 m². 2 / g; The degree of deacetylation of the chitosan used is ≥90%, and the molecular weight is 50,000-200,000. The degree of alcoholysis of the polyvinyl alcohol used is 85-99%, and the molecular weight is 5000-20000. The nano-cerium oxide used has a particle size of 20-60 nm and a purity of ≥99%.

[0021] Example 1 An absorbent for capturing carbon dioxide comprises, by weight, the following raw materials: 40 parts of a complex amine component, 10 parts of an activator (piperazine), 6 parts of a phase separation promoter (sulfolane), 3 parts of modified silica, 5 parts of a modifier, 1.5 parts of an anti-degradation agent (sodium sulfite), 1 part of a corrosion inhibitor (sodium vanadate), and 30 parts of water.

[0022] The compound amine components are formulated as follows: N-(2-hydroxyethyl)ethylenediamine, diethylenetriamine, and N-methyldiethanolamine are compounded in a weight ratio of 3.5:2:1.5.

[0023] In this embodiment, the nano-silica has a particle size of 40 nm and a specific surface area of ​​200 m². 2 / g; the degree of deacetylation of the chitosan is 92%, and the molecular weight is 100,000; the degree of alcoholysis of the polyvinyl alcohol is 88%, and the molecular weight is 12,000; the particle size of the nano-cerium oxide is 40nm.

[0024] The production process of absorbent: 1) Weigh each component according to its weight parts; 2) Add the composite amine components and water to the reaction vessel and stir at 300 r / min for 15 min at 30℃ to obtain the amine mother liquor; 3) Add piperazine and sulfolane to the amine mother liquor, and continue stirring for 20 minutes to obtain a mixture; 4) Add the modified silica and the modifier to the mixture, and ultrasonically disperse for 30 min (power 400W, frequency 50kHz), while controlling the temperature at 30℃ to obtain the nanocomposite liquid; Preparation of modified silica: a1) Add nano-silica to sufficient anhydrous ethanol and ultrasonically disperse for 35 min (power 350W) to obtain silica dispersion; a2) Add 8% by weight of silane coupling agent KH550 to the silica dispersion and stir at 70°C for 2.5 h to obtain silane-modified silica. a3) Add 12% by weight of glycidyl methacrylate and 0.8% by weight of benzoyl peroxide to silane-modified silica, and perform a polymerization grafting reaction at 78°C for 4 hours. Filter, wash with ethanol, and dry to obtain modified silica. Preparation of the blending agent: b1) Dissolve 5 parts of chitosan in 120 parts of 2% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; b2) Add 3.5 parts of polyvinyl alcohol, 2 parts of nano-cerium oxide and 1 part of citric acid to the chitosan solution, and stir at 60°C for 1.5 h to obtain the composite modified solution; b3) Spray dry the composite modified liquid with an inlet temperature of 180°C and an outlet temperature of 90°C to obtain chitosan-based composite microspheres, which are the additives. 5) Add sodium sulfite and sodium vanadate to the nanocomposite liquid, and stir at 400 r / min for 30 min at 40℃ to obtain crude absorbent; 6) Filter the crude absorbent using a 0.45 μm filter membrane and allow the filtrate to stand to defoam. 7) Sampling and testing are conducted. If the sample passes the test, it is then filled into a container to obtain the carbon dioxide capture absorbent.

[0025] Example 2 An absorbent for capturing carbon dioxide comprises the following raw materials by weight: 30 parts of a complex amine component, 5 parts of an activator (aminoethylpiperazine), 3 parts of a phase separation promoter (n-propanol), 1 part of modified silica, 2 parts of a conditioning agent, 0.5 parts of an anti-degradation agent (potassium sulfite), 0.5 parts of a corrosion inhibitor (sodium molybdate), and 20 parts of water.

[0026] The compound amine components are: N-(2-hydroxyethyl)ethylenediamine, diethylenetriamine and N-methyldiethanolamine are compounded in a weight ratio of 2:1:1.

[0027] In this embodiment, the nano-silica has a particle size of 20 nm and a specific surface area of ​​150 m². 2 / g; the degree of deacetylation of the chitosan is 95%, and the molecular weight is 40,000; the degree of alcoholysis of the polyvinyl alcohol is 99%, and the molecular weight is 20,000; the particle size of the nano-cerium oxide is 40nm.

[0028] The production process of absorbent: 1) Weigh each component according to its weight parts; 2) Add the complex amine components and water to the reaction vessel, and stir at 200 r / min for 10 min at 40℃ to obtain the amine mother liquor; 3) Add aminoethylpiperazine and n-propanol to the amine mother liquor, and continue stirring for 15 minutes to obtain a mixture; 4) Add the modified silica and the modifier to the mixture, and ultrasonically disperse for 20 min (power 500W, frequency 40kHz), while controlling the temperature at 40℃ to obtain the nanocomposite liquid; Preparation of modified silica: a1) Add nano-silica (particle size 20nm) to sufficient anhydrous ethanol and ultrasonically disperse for 30min (power 400W) to obtain silica dispersion; a2) Add 5% by weight of silane coupling agent KH550 to the silica dispersion and stir at 60°C for 3 hours to obtain silane-modified silica. a3) Add 8% by weight of glycidyl methacrylate and 0.5% by weight of benzoyl peroxide to silane-modified silica, and perform a polymerization grafting reaction at 70°C for 5 hours. Filter, wash with ethanol, and dry to obtain modified silica. Preparation of the blending agent: b1) Dissolve 3 parts of chitosan (degree of deacetylation 92%, molecular weight 100,000) in 100 parts of 1% acetic acid solution and stir until completely dissolved to obtain chitosan solution; b2) Add 2 parts of polyvinyl alcohol (88% degree of alcoholysis, molecular weight 12000), 1 part of nano-cerium oxide (particle size 40nm) and 0.5 parts of citric acid to the chitosan solution, and stir at 50℃ for 2 h to obtain the composite modified solution. b3) Spray dry the composite modified liquid with an inlet temperature of 160°C and an outlet temperature of 80°C to obtain chitosan-based composite microspheres, which are the additives. 5) Add potassium sulfite and sodium molybdate to the nanocomposite liquid, and stir at 300 r / min for 20 min at 50℃ to obtain crude absorbent; 6) Filter the crude absorbent using a 0.45 μm filter membrane and allow the filtrate to stand to defoam. 7) Sampling and testing are conducted. If the sample passes the test, it is then filled into a container to obtain the carbon dioxide capture absorbent.

[0029] Example 3 An absorbent for capturing carbon dioxide comprises, by weight, the following raw materials: 50 parts of a complex amine component, 15 parts of an activator (N-hydroxyethylpiperazine), 10 parts of a phase separation promoter (dimethyl sulfoxide), 5 parts of modified silica, 8 parts of a conditioning agent, 3 parts of an anti-degradation agent (ammonium sulfite), 2 parts of a corrosion inhibitor (benzotriazole), and 40 parts of water.

[0030] The compound amine components are formulated as follows: N-(2-hydroxyethyl)ethylenediamine, diethylenetriamine, and N-methyldiethanolamine are compounded in a weight ratio of 5:3:2.

[0031] In this embodiment, the nano-silica has a particle size of 80 nm and a specific surface area of ​​300 m².2 / g; the degree of deacetylation of the chitosan is 90%, and the molecular weight is 200,000; the degree of alcoholysis of the polyvinyl alcohol is 85%, and the molecular weight is 5,000; the particle size of the nano-cerium oxide is 60nm.

[0032] The production process of absorbent: 1) Weigh each component according to its weight parts; 2) Add the composite amine components and water to the reaction vessel and stir at 400 r / min for 20 min at 25℃ to obtain the amine mother liquor; 3) Add N-hydroxyethylpiperazine and dimethyl sulfoxide to the amine mother liquor, and continue stirring for 30 min to obtain a mixture; 4) Add the modified silica and the modifier to the mixture and ultrasonically disperse for 40 min (power 300W, frequency 40kHz) to obtain the nanocomposite liquid; Preparation of modified silica: a1) Add nano-silica (particle size 80nm) to sufficient anhydrous ethanol and ultrasonically disperse for 45min (power 300W) to obtain silica dispersion; a2) Add 10% by weight of silane coupling agent KH550 to the silica dispersion and stir at 80°C for 2 hours to obtain silane-modified silica. a3) Add 15% by weight of glycidyl methacrylate and 1% benzoyl peroxide to silane-modified silica, and perform a polymerization grafting reaction at 85°C for 3 hours. Filter, wash with ethanol, and dry to obtain modified silica. Preparation of the blending agent: b1) Dissolve 8 parts of chitosan in 150 parts of 3% acetic acid solution and stir until completely dissolved to obtain a chitosan solution; b2) Add 5 parts polyvinyl alcohol, 3 parts nano-cerium oxide and 2 parts citric acid to the chitosan solution, and stir at 70°C for 1 hour to obtain the composite modified solution; b3) Spray dry the composite modified liquid with an inlet temperature of 200°C and an outlet temperature of 100°C to obtain chitosan-based composite microspheres, which are the additives. 5) Add ammonium sulfite and benzotriazole to the nanocomposite liquid, and stir at 500 r / min for 40 min at 30℃ to obtain crude absorbent; 6) Filter the crude absorbent using a 0.45 μm filter membrane and allow the filtrate to stand to defoam. 7) Sampling and testing are conducted. If the sample passes the test, it is then filled into a container to obtain the carbon dioxide capture absorbent.

[0033] Comparative Example 1 As a control group for Example 1, no modified silica was added in the preparation of the absorbent in Comparative Example 1, and the rest was the same as in Example 1.

[0034] Comparative Example 2 As a control group for Example 1, in the preparation of the absorbent in Comparative Example 2, the modified silica was not grafted polymerized (only KH550 was modified), and the rest was the same as in Example 1.

[0035] Comparative Example 3 As a control group for Example 1, no additive was added in the preparation of the absorbent in Comparative Example 3, and the rest was the same as in Example 1.

[0036] Comparative Example 4 As a control group for Example 1, in the preparation of the absorbent in Comparative Example 4, no nano-cerium oxide was added to the additive, and the rest was the same as in Example 1.

[0037] Comparative Example 5 As a control group for Example 1, in the preparation of the absorbent in Comparative Example 5, diethylenetriamine was not added to the complex amine component, and the rest was the same as in Example 1.

[0038] Comparative Example 6 As a control group for Example 1, no phase separation promoter was added in the preparation of the absorbent in Comparative Example 6, and the rest was the same as in Example 1.

[0039] Comparative Example 7 As a control group for Example 1, in the preparation of the absorbent in Comparative Example 7, a conventional 30% MEA aqueous solution was used.

[0040] The absorbents prepared in the examples and comparative examples were tested for CO2 absorption performance, CO2 desorption performance and energy consumption, as well as antioxidant and anti-corrosion performance. The results are as follows: Table 1. CO2 Absorption Performance Test Results Group <![CDATA[Saturated absorption capacity (mol CO2 / L)]]> Initial absorption rate (mmol / L·s) Absorption rate at 60 min (%) Capacity after cyclic stabilization (mol / L) Example 1 4.3 4.02 93 3.9 Example 2 3.9 3.68 89 3.5 Example 3 4.6 4.28 95 4.2 Comparative Example 1 4.0 3.42 88 3.6 Comparative Example 2 4.1 3.55 89 3.7 Comparative Example 3 4.1 3.78 90 3.7 Comparative Example 4 4.2 3.85 91 3.8 Comparative Example 5 3.6 3.35 83 3.1 Comparative Example 6 3.9 3.45 86 3.4 Comparative Example 7 2.8 3.50 75 1.5 As shown in Table 1, the saturated absorption capacity of Examples 1-3 reached 3.9-4.6 mol / L, and the initial absorption rate was 3.68-4.28 mmol / L·s, which was superior to Comparative Examples 1-7. The absorption capacity of Comparative Example 5 (deficient DETA) decreased, and the absorption rate of Comparative Examples 1-2 (incomplete modified silica) decreased. This indicates that modified silica made a more significant contribution to improving the absorption rate, which is attributed to the increased gas-liquid-solid three-phase contact area due to the polymer chains grafted on its surface, thus enhancing the mass transfer process. The modifier made a greater contribution to maintaining the stability of the absorption capacity, which may be due to its porous structure and the fact that the amino functional groups of chitosan also participated in CO2 adsorption. When both coexisted (Example 1), the absorption capacity and absorption rate were simultaneously improved, demonstrating the differentiated complementary and synergistic effects of their functions.

[0041] Capacity data after cyclic stabilization showed that the capacity decay of Examples 1-3 was minimal (decay rate of approximately 5-9%), while the decay rate of Comparative Example 7 (conventional MEA) was as high as 46%. The excellent cyclic stability of the absorbent of this invention is attributed to the stable dispersion of modified silica and the effective inhibition of amine liquid degradation by nano-CeO2 and citric acid in the additive.

[0042] Table 2. Results of CO2 desorption performance and energy consumption tests Group Desorption rate (%, 110℃) <![CDATA[Regeneration energy consumption (GJ / tCO₂)]]> Volume ratio of rich phase (%) Example 1 83 2.35 40 Example 2 79 2.52 36 Example 3 86 2.28 44 Comparative Example 1 81 2.42 40 Comparative Example 2 80 2.45 40 Comparative Example 3 82 2.38 40 Comparative Example 4 82 2.38 40 Comparative Example 5 72 2.78 No phase Comparative Example 6 76 2.82 — Comparative Example 7 55 3.85 No phase As shown in Table 2, the regeneration energy consumption of Examples 1-3 is only 2.28-2.52 GJ / t CO2, which is 34.5%-40.8% higher than that of the traditional MEA process (Comparative Example 7, 3.85 GJ / t CO2).

[0043] Based on the volume ratio data of the rich phase (36-44%), it can be seen that the addition of the phase separation promoter enables the rich liquid after CO2 absorption to spontaneously separate into two phases after settling. CO2 is highly enriched in the rich phase, which accounts for only 36-44% of the volume. This means that in the desorption stage, only the rich phase, which accounts for less than half of the total volume, needs to be heated and regenerated, while the lean phase (approximately 56-64%) can be directly recycled back to the absorption tower, thereby significantly reducing the total amount of liquid that needs to be heated.

[0044] Compared with Example 1 and Comparative Example 6 (without phase separation promoter), the latter's regeneration energy consumption increased to 2.82 GJ / t CO2, and no phase separation phenomenon was observed. This indicates that the phase separation promoter is the core component for achieving low energy consumption. Furthermore, the presence of modified silica and the conditioning agent may further promote the rate and effectiveness of phase separation by improving the microstructure of the solution (the rich phase volume ratio of Example 1 was 40%, superior to other examples), forming a virtuous cycle of efficient absorption-rapid phase separation-low energy regeneration.

[0045] Table 3 Results of Antioxidant and Anticorrosion Performance Tests Group Accelerate oxidative degradation rate (%, 120h) Iron ion leaching concentration (mg / L, 720h) <![CDATA[Absorbent loss rate (kg / t CO₂) <!-- 7 -->]]> Example 1 7.2 15.5 0.72 Example 2 8.5 18.2 0.85 Example 3 6.8 14.5 0.68 Comparative Example 1 10.5 22.5 1.15 Comparative Example 2 10.2 21.8 1.10 Comparative Example 3 12.8 28.5 1.42 Comparative Example 4 11.5 25.5 1.28 Comparative Example 5 12.0 26.0 1.32 Comparative Example 6 11.2 24.0 1.22 Comparative Example 7 18.5 52.0 2.20 As shown in Table 3, the oxidative degradation rate (7.2%) and iron ion dissolution concentration (15.5 mg / L) of Example 1 are significantly lower than those of Comparative Example 7 (18.5%, 52.0 mg / L). The nano-CeO2 in the additive of this invention utilizes its Ce... 3+ / Ce 4+ The variable valence property continuously quenches free radicals generated during amine oxidation, inhibiting the degradation reaction (comparative example 4, without the addition of nano-CeO2, showed a degradation rate increased to 11.5%). The citric acid and the amino and hydroxyl groups on the chitosan molecular chains in the additive of this invention can effectively chelate metal ions (such as Fe) dissolved from equipment corrosion. 3+The modified silica surface of this invention prevents the oxidative degradation of amines (Comparative Example 3, without additives, showed the highest metal ion dissolution and degradation rates). The polymer chains on the surface of the modified silica may reduce the effective collision probability between free radicals and amine molecules through steric hindrance or electrostatic effects, further enhancing the antioxidant performance (Comparative Example 1, without modified silica, also showed a degradation rate of 10.5%).

[0046] Regarding corrosion inhibition, an inorganic corrosion inhibitor (vanadate / molybdate), an organic corrosion inhibitor (benzotriazole), and chitosan and nano-CeO2 in the additives form an organic-inorganic composite corrosion inhibitor film. This composite film can form a dense protective layer on the carbon steel surface, effectively blocking the erosion of corrosive media such as Cl⁻ and CO₂-H₂O, as evidenced by the extremely low iron ion leaching concentrations in Examples 1-3.

[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0048] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An absorbent for capturing carbon dioxide, characterized in that, The raw materials, by weight, include: 30-50 parts of compound amine components, 5-15 parts of activator, 3-10 parts of phase separation promoter, 1-5 parts of modified silica, 2-8 parts of additive, 0.5-3 parts of anti-degradation agent, 0.5-2 parts of corrosion inhibitor, and 20-40 parts of water. The complex amine component is composed of N-(2-hydroxyethyl)ethylenediamine, diethylenetriamine and N-methyldiethanolamine in a weight ratio of (2-5):(1-3):(1-2); The modified silica is prepared by the following steps: a1) Add nano-silica to sufficient anhydrous ethanol and ultrasonically disperse for 30-45 min at an ultrasonic power of 300-400 W to obtain a silica dispersion. a2) Add 5-10% by weight of silane coupling agent KH550 to the silica dispersion and stir at 60-80℃ for 2-3 hours to obtain silane-modified silica. a3) Add 8-15% by weight of an organic grafting monomer to silane-modified silica, wherein the organic grafting monomer is glycidyl methacrylate or acrylamide, and simultaneously add 0.5-1% of the initiator benzoyl peroxide. Perform a polymerization grafting reaction at 70-85℃ for 3-5 hours. After the reaction is completed, filter, wash with ethanol, and dry to obtain modified silica. The additive is prepared by the following steps: b1) Dissolve 3-8 parts of chitosan in 100-150 parts of acetic acid solution with a mass fraction of 1-3%, and stir until completely dissolved to obtain a chitosan solution; b2) Add 2-5 parts of polyvinyl alcohol, 1-3 parts of nano-cerium oxide and 0.5-2 parts of citric acid to the chitosan solution, and stir at 50-70℃ for 1-2 hours to obtain the composite modified solution; b3) Spray dry the composite modified liquid with an inlet temperature of 160-200℃ and an outlet temperature of 80-100℃ to obtain chitosan-based composite microspheres, which are the additives. The activator is at least one of piperazine, N-hydroxyethylpiperazine or aminoethylpiperazine; The phase separation promoter is at least one of sulfolane, n-propanol, isopropanol, or dimethyl sulfoxide.

2. The absorbent for capturing carbon dioxide according to claim 1, characterized in that, The nano-silica has a particle size of 20-80 nm and a specific surface area of ​​150-300 m². 2 / g; the weight ratio of the silane coupling agent KH550 to nano silica is (0.05-0.1):

1.

3. The absorbent for capturing carbon dioxide according to claim 1, characterized in that, The chitosan has a degree of deacetylation ≥90% and a molecular weight of 50,000-200,000; the polyvinyl alcohol has a degree of alcoholysis 85-99% and a molecular weight of 5,000-20,000; the nano-cerium oxide has a particle size of 20-60 nm and a purity ≥99%.

4. The absorbent for capturing carbon dioxide according to claim 1, characterized in that, The anti-degradation agent is at least one of sodium sulfite, potassium sulfite, ammonium sulfite, or ethylenediaminetetraacetic acid; the corrosion inhibitor is at least one of vanadate, molybdate, or benzotriazole.

5. A production process for the carbon dioxide capture absorbent according to any one of claims 1-4, characterized in that, Includes the following steps: 1) Weigh out the following components by weight: amine complex, activator, phase separation promoter, modified silica, conditioning agent, anti-degradation agent, corrosion inhibitor, and water. 2) Add the complex amine components and water to the reaction vessel, and stir at 200-400 r / min for 10-20 min at 25-40℃ to obtain the amine mother liquor; 3) Add activator and phase separation promoter to the amine mother liquor, and continue stirring for 15-30 minutes to obtain a mixture; 4) Add the modified silica and the modifier to the mixture and ultrasonically disperse for 20-40 minutes to obtain the nanocomposite liquid; 5) Add anti-degradation agent and corrosion inhibitor to the nanocomposite liquid, and stir at 300-500 r / min for 20-40 min at 30-50℃ to obtain crude absorbent; 6) Filter the crude absorbent with a filter membrane pore size of 0.45-1.0 μm, and let the filtrate stand to defoam; 7) Sampling and testing are conducted. If the sample passes the test, it is then filled into a container to obtain the carbon dioxide capture absorbent.

6. The production process of the carbon dioxide capture absorbent according to claim 5, characterized in that, In step 4), the ultrasonic dispersion power is 300-500W, the ultrasonic frequency is 40-60kHz, and the temperature is controlled at 25-40℃.