Adsorbents for air carbon capture, their preparation methods and applications

Abstract

This invention relates to an adsorbent for capturing carbon in the air. The adsorbent is carbon nanotubes modified with amine compounds and additives, wherein the additives are selected from at least one of polyglycol compounds, polyepoxide compounds, and alkyl titanates. The adsorbent provided by this invention introduces amine compounds and additives during the modification of carbon nanotubes. The polyglycol and polyepoxide compounds possess certain flexibility and dispersibility, which helps the amine compounds to be better dispersed on the surface of the carbon nanotubes, reducing agglomeration. They may also participate in the interaction with carbon dioxide, further enhancing the adsorption effect. The alkyl titanates can form chemical bonds with the surface of the carbon nanotubes, enhancing the binding force between the amine compounds and the carbon nanotubes, and improving the stability and reusability of the adsorbent. This invention also relates to a method for preparing the adsorbent for capturing carbon in the air, and a method and apparatus for capturing carbon in the air.

Description

Technical Field

[0001] This invention relates to the technical field of adsorbents for air carbon capture, and more particularly to an adsorbent for air carbon capture, its preparation method, and its application. This invention provides a wind-powered air carbon capture technology, aiming to effectively reduce the concentration of carbon dioxide in the air and address climate change by combining wind energy with carbon capture technology. Background Technology

[0002] With the acceleration of global industrialization, human activities have released large amounts of greenhouse gases such as carbon dioxide into the atmosphere. The continuous rise in atmospheric carbon dioxide concentration has triggered a series of serious climate change problems, such as rising global temperatures, melting glaciers, rising sea levels, and frequent extreme weather events. These phenomena pose a huge threat to the balance of ecosystems, the human living environment, and global economic development.

[0003] Traditional carbon capture technologies primarily focus on capturing high concentrations of carbon dioxide from industrial emission sources (such as power plants, cement plants, and steel mills). However, research and application of capturing low concentrations of carbon dioxide (approximately 400-500 ppm) in the atmosphere are relatively limited. In reality, the total amount of carbon dioxide in the atmosphere is enormous, and its accumulation is a key factor in global climate change. Therefore, developing efficient air carbon capture technologies is of paramount importance for addressing climate change.

[0004] Carbon nanotubes, due to their unique physicochemical properties such as large specific surface area, good chemical stability, and tunable pore structure, have shown potential application value in the field of adsorption. However, the adsorption performance of unmodified carbon nanotubes for carbon dioxide often fails to meet the practical requirements of airborne carbon capture. Amine compounds contain amino groups, which have good chemisorption properties for carbon dioxide and can react chemically with carbon dioxide, thereby improving the adsorption capacity and selectivity. However, pure amine compounds may have some limitations in the adsorption process, such as easy aggregation and insufficient adsorption stability.

[0005] Against this backdrop, developing an adsorbent for air carbon capture has significant scientific value and practical application prospects, and is expected to provide a new technological approach and effective means to address global climate change. Summary of the Invention

[0006] Based on the above, the purpose of this invention is to provide an adsorbent for air carbon capture, its preparation method, and its application. The adsorbent for air carbon capture provided by this invention is used to efficiently capture carbon dioxide from the air, thereby effectively reducing the concentration of carbon dioxide in the air and addressing the problem of climate change.

[0007] Therefore, the present invention provides an adsorbent for air carbon capture, wherein the adsorbent is carbon nanotube modified with amine compounds and additives, and the additives are selected from at least one of polydiol compounds, polyepoxide compounds, and alkyl titanates.

[0008] The adsorbent provided by this invention introduces amine compounds and additives during the modification of carbon nanotubes. Polydiol and polyepoxide compounds possess certain flexibility and dispersibility, which helps the amine compounds to disperse better on the carbon nanotube surface, reducing aggregation. They may also participate in the interaction with carbon dioxide, further enhancing the adsorption effect. Alkyl titanate compounds can form chemical bonds with the carbon nanotube surface, strengthening the binding force between the amine compounds and the carbon nanotubes, and improving the stability and reusability of the adsorbent.

[0009] As a specific embodiment of the present invention, the amine compound is selected from at least one of monoamine compounds and polyamine compounds.

[0010] As a specific embodiment of the present invention, the monoamine compound is selected from at least one of ethanolamine, methanolamine, and isopropanolamine.

[0011] As a specific embodiment of the present invention, the polyamine compound is selected from at least one of diethanolamine, triethanolamine, and polyethyleneimine.

[0012] As a specific embodiment of the present invention, the amine compound is selected from at least two of monoamine compounds and polyamine compounds.

[0013] As a specific embodiment of the present invention, the mass ratio of the monoamine compound to the polyamine compound is 1:0.5-2.

[0014] As a specific embodiment of the present invention, the carbon nanotubes have a specific surface area of ​​1000 m². 2 / g or more, preferably 1000m 2 / g-1300m 2 / g.

[0015] As a specific embodiment of the present invention, the average pore size of the carbon nanotubes is 3-50 nm.

[0016] As a specific embodiment of the present invention, the alkyl titanate is a tetraalkyl titanate with the general formula Ti(OR)4, wherein R is a C2-C6 alkyl group.

[0017] In a specific embodiment of the present invention, the tetraalkyl titanate is tetrabutyl titanate.

[0018] As a specific embodiment of the present invention, the carbon nanotubes are selected from at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0019] As a specific embodiment of the present invention, the average pore size of the single-walled carbon nanotube is 3-15 nm, more preferably 5-10 nm.

[0020] As a specific embodiment of the present invention, the average pore size of the multi-walled carbon nanotubes is 20-40 nm, more preferably 20-30 nm.

[0021] As a specific embodiment of the present invention, the single-walled carbon nanotubes are prepared by chemical vapor deposition or arc discharge.

[0022] As a specific embodiment of the present invention, the multi-walled carbon nanotubes are multi-walled carbon nanotubes prepared by chemical vapor deposition or catalytic pyrolysis.

[0023] As a specific embodiment of the present invention, the polydiol compound is selected from at least one of polyethylene glycol, polypropylene glycol, and polybutanediol.

[0024] As a specific embodiment of the present invention, the number-average molecular weight of the polydiol compound is 300-800 g / mol.

[0025] As a specific embodiment of the present invention, the number-average molecular weight of the polyethylene glycol is 350-600 g / mol.

[0026] As a specific embodiment of the present invention, the polyepoxide compound is selected from at least one of polyethylene oxide, polypropylene oxide, and polybutane oxide.

[0027] As a specific embodiment of the present invention, the number average molecular weight of the polyepoxide compound is 1000-3000 g / mol.

[0028] As a specific embodiment of the present invention, the number average molecular weight of the polyoxyethylene is 1500-2500 g / mol.

[0029] As a specific embodiment of the present invention, the method for modifying carbon nanotubes includes the following steps: adding amine compounds and auxiliaries to an organic solvent to prepare a modification solution, and adding carbon nanotubes to the modification solution to carry out a reaction.

[0030] As a specific embodiment of the present invention, the ratio of the amine compound to the organic solvent is 2-8g:100mL.

[0031] As a specific embodiment of the present invention, the ratio of the auxiliary agent to the organic solvent is 0.5-5g:100mL.

[0032] In a specific embodiment of the present invention, the ratio of the auxiliary agent to the organic solvent is 0.5-3.5 g: 100 mL. Within the above ratio range, excessive coating of the adsorbent surface by the auxiliary agent can be avoided, which would lead to an increase in regeneration temperature and energy consumption during regeneration.

[0033] As a specific embodiment of the present invention, the ratio of the carbon nanotubes to the modified solution is 0.5-3g:100mL.

[0034] As a specific embodiment of the present invention, the organic solvent is selected from at least one of ethanol, dichloromethane, and water.

[0035] Therefore, in a second aspect, the present invention provides a method for preparing the above-mentioned adsorbent for air carbon capture, characterized by comprising the following steps:

[0036] S1, carbon nanotube pretreatment;

[0037] S2. Preparation of modified solution: Amine compounds and auxiliaries are added to an organic solvent to prepare a modified solution;

[0038] S3. Adsorbent modification: The pretreated carbon nanotubes are mixed with the modification solution and reacted under stirring conditions to obtain modified carbon nanotubes.

[0039] S4. Drying and Activation: Activate the modified carbon nanotubes obtained in step S3.

[0040] As a specific embodiment of the present invention, the conditions for the modification of the adsorbent include: temperature 20-40℃ and time 2-12 hours.

[0041] As a specific embodiment of the present invention, the activation conditions include: under vacuum conditions, a temperature of 60-120°C, and a time of 2-12 hours.

[0042] In a specific embodiment of the present invention, the carbon nanotube pretreatment is selected from at least one of acidification treatment, heat treatment, and cleaning treatment. The preparation method of the present invention uses carbon nanotube pretreatment to remove impurities from the carbon nanotubes and enhance their surface activity.

[0043] As a specific embodiment of the present invention, the acidification treatment includes: placing the carbon nanotubes in an acid solution for ultrasonic treatment, followed by washing and drying.

[0044] As a specific embodiment of the present invention, the acid solution is nitric acid with a mass concentration of 30%-60% and / or sulfuric acid with a mass concentration of 20%-40%.

[0045] As a specific embodiment of the present invention, the acid solution is nitric acid with a mass concentration of 30%-60% and sulfuric acid with a mass concentration of 20%-40%, preferably with a volume ratio of nitric acid to sulfuric acid of 1:2-4.

[0046] As a specific embodiment of the present invention, the heat treatment includes: placing the carbon nanotubes at 300-500℃ for 1-3 hours.

[0047] As a specific embodiment of the present invention, the detergent used in the cleaning process is selected from at least one of acetone, diethyl ether, and n-hexane.

[0048] Therefore, in a third aspect, the present invention provides a method for capturing carbon in the air, comprising the following steps: contacting the adsorbent for capturing carbon in the air described above or the adsorbent for capturing carbon in the air prepared by the above preparation method with an airflow containing carbon dioxide to adsorb carbon dioxide in the air.

[0049] In a specific embodiment of the present invention, the concentration of carbon dioxide in the airflow is 400-500 ppm.

[0050] As a specific embodiment of the present invention, the adsorbent for air carbon capture is regenerated by heat treatment, more preferably, the temperature of the heat treatment is 80-120°C.

[0051] As a specific embodiment of the present invention, the heat treatment is performed in a vacuum environment.

[0052] Therefore, in a fourth aspect, the present invention provides an air carbon capture device comprising the above-described adsorbent for air carbon capture or the adsorbent for air carbon capture prepared by the above-described preparation method.

[0053] As a specific embodiment of the present invention, the device is used to capture carbon dioxide generated by power plants, industrial production processes or transportation.

[0054] The beneficial effects of this invention are:

[0055] The adsorbent provided by this invention is a carbon nanotube modified with amine compounds and specific additives. It combines the large specific surface area of ​​carbon nanotubes with the chemical adsorption of carbon dioxide by amine compounds and the synergistic effect of additives. It can effectively capture carbon dioxide from low concentrations (400-500 ppm) of air. Compared with traditional adsorbents, it has higher adsorption capacity and selectivity, and can significantly reduce the concentration of carbon dioxide in the air, thus playing a positive role in mitigating climate change.

[0056] The adsorbents and additives provided by this invention, such as alkyl titanates, can enhance the binding force between amine compounds and carbon nanotubes, reduce the loss of active components during the adsorption-regeneration cycle, and give the adsorbent good stability and reusability, thereby reducing the cost of use and improving the economy and sustainability of the process.

[0057] The adsorbent provided by this invention has various pretreatment methods for carbon nanotubes, including acidification, heat treatment and cleaning, which can be selected and combined according to actual needs and raw material characteristics. Moreover, the conditions in the preparation of the modified solution and the modification process of the adsorbent are relatively mild, easy to operate and control, and conducive to large-scale industrial production.

[0058] The adsorbent provided by this invention is easy to regenerate. It adopts a heat treatment regeneration method, which can realize the regeneration of the adsorbent in a vacuum environment of 80-120℃. The regeneration energy consumption is low, the regeneration process is relatively simple, and it can quickly restore the adsorption performance of the adsorbent, ensuring the continuity and efficiency of the adsorption process, and further improving the practicality and economy of the entire carbon capture process.

[0059] The adsorbent, air carbon capture method, and apparatus provided by this invention have broad application prospects. This air carbon capture device can be applied to end-of-pipe treatment or environmental remediation of multiple carbon dioxide emission sources such as power plants, industrial production processes, or transportation, helping to reduce the contribution of these sectors to atmospheric carbon dioxide emissions. While addressing global climate change, it also meets the needs of green and low-carbon development in various industries, possessing extremely broad market application potential and environmental and social benefits. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the invention and should not be considered as specific limitations thereof. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0061] Example 1

[0062] The single-walled carbon nanotubes selected have a specific surface area of ​​1100 m². 2 / g, with an average pore size of 7.5nm;

[0063] (1) Pretreatment of carbon nanotubes:

[0064] A mixed acid solution is obtained by mixing 40% nitric acid and 30% sulfuric acid at a volume ratio of 1:3.

[0065] 5g of single-walled carbon nanotubes were placed in 50mL of mixed acid solution and sonicated for 2 hours to remove impurities. They were then washed with deionized water until neutral and dried for later use.

[0066] (2) Modification

[0067] Add 2.0 g ethanolamine and 1.0 g polyethylene glycol (number average molecular weight of 400 g / mol) to 50 mL of anhydrous ethanol, and stir until completely dissolved to obtain a modified solution;

[0068] 1.0 g of pretreated single-walled carbon nanotubes were added to the modification solution and stirred at room temperature for 6 hours. After the reaction, the mixture was filtered and washed to obtain the modified single-walled carbon nanotubes.

[0069] (3) Drying and activation

[0070] The modified single-walled carbon nanotubes were placed in a vacuum drying oven and dried at 60°C for 8 hours to obtain the adsorbent product.

[0071] (4) Performance Testing

[0072] The adsorbent product was used in an experiment to capture carbon dioxide in an air stream. The volume concentration of CO2 in the air stream was 400 ppm, and the air stream flow rate was 1 L / min. After 60 minutes, the adsorption capacity reached 2.5 mmol / g.

[0073] After the above-mentioned adsorbent products were regenerated by heat treatment at 120°C and in a vacuum environment for 60 minutes, their adsorption performance was restored to 92% of that of fresh adsorbents, and there was no significant performance degradation after 20 cycles of use.

[0074] Comparative Example 1

[0075] The selected single-walled carbon nanotubes have a specific surface area of ​​1100 m². 2 / g, with an average pore size of 7.5nm;

[0076] (1) Pretreatment of carbon nanotubes:

[0077] A mixed acid solution is obtained by mixing 40% nitric acid and 30% sulfuric acid at a volume ratio of 1:3.

[0078] 5g of single-walled carbon nanotubes were placed in 50mL of mixed acid solution and sonicated for 2 hours to remove impurities, and then washed with deionized water until neutral.

[0079] (2) Drying and activation

[0080] The washed single-walled carbon nanotubes were placed in a vacuum drying oven and dried at 60°C for 8 hours to obtain the adsorbent product.

[0081] (3) Performance Testing

[0082] The adsorbent product was used in an experiment to capture carbon dioxide in an air stream. The volume concentration of CO2 in the air stream was 400 ppm, and the air stream flow rate was 1 L / min. After 60 minutes, the adsorption capacity was only 0.8 mmol / g.

[0083] The adsorbent product, after being regenerated by heat treatment at 120℃ in a vacuum environment for 60 minutes, showed no significant performance degradation after 5 cycles of use. However, its adsorption performance decreased by more than 50%. This indicates that the unmodified carbon nanotubes have poor adsorption performance and poor regeneration performance.

[0084] Comparative Example 2

[0085] The difference from Example 1 is that in step (2), 1.0g of polyethylene glycol is replaced with 1.0g of ethanolamine.

[0086] The performance test results showed that the adsorption capacity was 1.5 mmol / g.

[0087] The adsorption capacity of the adsorbent product in this comparative example is lower than that of the adsorbent product in Example 1, indicating that the auxiliary agent polyethylene glycol plays an important role in improving the modification effect of carbon nanotubes.

[0088] Example 2

[0089] The specific surface area of ​​the multi-walled carbon nanotubes selected is 1250 m². 2 / g, with an average pore size of 25nm;

[0090] (1) Pretreatment of carbon nanotubes:

[0091] Under nitrogen protection, multi-walled carbon nanotubes were heated to 400℃ and held for 2 hours to enhance their surface activity.

[0092] (2) Modification

[0093] Add 3.0 g of diethanolamine and 2.0 g of ethylene oxide polymer (number average molecular weight of 2000 g / mol) to 100 mL of dichloromethane, stir until homogeneous, and obtain a modified solution;

[0094] 2.0 g of pretreated single-walled carbon nanotubes were added to the modification solution, heated to 40 °C and stirred for 8 hours. After the reaction, the mixture was filtered and washed to obtain the modified single-walled carbon nanotubes.

[0095] (3) Drying and activation

[0096] The modified single-walled carbon nanotubes were placed in a vacuum drying oven and dried at 100°C for 6 hours to obtain the adsorbent product.

[0097] (4) Performance Testing

[0098] The adsorbent product was used in an experiment to capture carbon dioxide in an air stream. The volume concentration of CO2 in the air stream was 400 ppm, and the air stream flow rate was 1 L / min. After 45 minutes, the adsorption capacity reached 3.2 mmol / g.

[0099] After the above-mentioned adsorbent product was regenerated by heat treatment at 90℃ for 45 minutes, its adsorption performance remained at 96%, and there was no significant performance degradation after 20 cycles of use.

[0100] Example 3

[0101] The difference from Example 2 is that in step (2), 2.0g of ethylene oxide polymer is replaced with 4.0g of ethylene oxide polymer.

[0102] The performance test results showed that the adsorption capacity was 3.0 mmol / g.

[0103] The adsorption capacity of the adsorbent product in this embodiment is similar to that of the adsorbent product in Example 2, but the adsorbent product needs to be regenerated by heat treatment at 150°C for 60 minutes, which increases the regeneration energy consumption.

[0104] Example 4

[0105] The specific surface area of ​​the multi-walled carbon nanotubes selected is 1250 m². 2 / g, pore size is 25nm;

[0106] (1) Pretreatment of carbon nanotubes:

[0107] A mixed acid solution is obtained by mixing 50% nitric acid and 25% sulfuric acid at a volume ratio of 1:3.

[0108] 5g of single-walled carbon nanotubes were placed in 50mL of mixed acid solution and sonicated for 2 hours to remove impurities. They were then washed with deionized water until neutral and dried for later use.

[0109] (2) Modification

[0110] Add 2.0 g methylamine, 1.5 g polyethyleneimine and 0.5 g tetrabutyl titanate to 50 mL of anhydrous ethanol, stir well to obtain a modified solution;

[0111] 2.0g of pretreated multi-walled carbon nanotubes were added to the modification solution, heated to 60℃ and stirred for 10 hours. After the reaction, the mixture was filtered and washed to obtain the modified multi-walled carbon nanotubes.

[0112] (3) Drying and activation

[0113] The modified multi-walled carbon nanotubes were placed in a vacuum drying oven and dried at 80°C for 8 hours to obtain the adsorbent product.

[0114] (4) Performance Testing

[0115] The adsorbent product was used in an experiment to capture carbon dioxide in an air stream. The volume concentration of CO2 in the air stream was 400 ppm, and the air stream flow rate was 1 L / min. After 30 minutes, the adsorption capacity reached 4.0 mmol / g.

[0116] After the above-mentioned adsorbent product is regenerated by heat treatment at 85℃ for 30 minutes, the adsorption performance remains at 96%, and after being recycled 20 times, the adsorption performance remains above 95%.

[0117] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An adsorbent for capturing carbon from the air, characterized in that, The adsorbent is a carbon nanotube modified with amine compounds and additives, wherein the additives are selected from at least one of polydiol compounds, polyepoxide compounds, and alkyl titanates.

2. The adsorbent according to claim 1, characterized in that, The amine compound is selected from at least one of monoamine compounds and polyamine compounds; Preferably, the monoamine compound is selected from at least one of ethanolamine, methanolamine, and isopropanolamine; Preferably, the polyamine compound is selected from at least one of diethanolamine, triethanolamine, and polyethyleneimine; More preferably, the amine compound is selected from at least two of monoamine compounds and polyamine compounds; even more preferably, the mass ratio of the monoamine compound to the polyamine compound is 1:0.5-2.

3. The adsorbent according to claim 1 or 2, characterized in that, The specific surface area of ​​the carbon nanotubes is 1000 m². 2 / g or more, preferably 1000m 2 / g-1300m 2 / g; and / or The carbon nanotubes have an average pore size of 3-50 nm; and / or The alkyl titanate is a tetraalkyl titanate with the general formula Ti(OR)4, wherein R is a C2-C6 alkyl group; preferably, the tetraalkyl titanate is a tetrabutyl titanate.

4. The adsorbent according to any one of claims 1-3, characterized in that, The carbon nanotubes are selected from at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes; Preferably, the average pore size of the single-walled carbon nanotubes is 3-15 nm, more preferably 5-10 nm; Preferably, the average pore size of the multi-walled carbon nanotubes is 20-40 nm, more preferably 20-30 nm; Preferably, the single-walled carbon nanotubes are prepared by chemical vapor deposition or arc discharge. Preferably, the multi-walled carbon nanotubes are multi-walled carbon nanotubes prepared by chemical vapor deposition or catalytic pyrolysis.

5. The adsorbent according to claim 4, characterized in that, The polyglycol compound is selected from at least one of polyethylene glycol, polypropylene glycol, and polybutanediol; preferably, the number-average molecular weight of the polyglycol compound is 300-800 g / mol; more preferably, the number-average molecular weight of the polyethylene glycol is 350-600 g / mol; and / or The polyepoxide compound is selected from at least one of polyethylene oxide, polypropylene oxide, and polybutane; preferably, the number-average molecular weight of the polyepoxide compound is 1000-3000 g / mol; more preferably, the number-average molecular weight of the polyethylene oxide is 1500-2500 g / mol.

6. The adsorbent according to any one of claims 1-5, characterized in that, The method for modifying carbon nanotubes includes the following steps: adding amine compounds and auxiliaries to an organic solvent to prepare a modification solution, and adding carbon nanotubes to the modification solution to carry out a reaction; Preferably, the ratio of the amine compound to the organic solvent is 2-8 g: 100 mL; Preferably, the ratio of the auxiliary agent to the organic solvent is 0.5-5g:100mL, more preferably 0.5-3.5g:100mL; Preferably, the ratio of the carbon nanotubes to the modified solution is 0.5-3g:100mL; Preferably, the organic solvent is selected from at least one of ethanol, dichloromethane, and water.

7. A method for preparing an adsorbent for airborne carbon capture according to any one of claims 1-6, characterized in that, Includes the following steps: S1, carbon nanotube pretreatment; S2. Preparation of modified solution: Amine compounds and auxiliaries are added to an organic solvent to prepare a modified solution; S3. Adsorbent modification: The pretreated carbon nanotubes are mixed with the modification solution and reacted under stirring conditions to obtain modified carbon nanotubes. S4. Drying and Activation: Activate the modified carbon nanotubes obtained in step S3. Preferably, the conditions for modifying the adsorbent include: temperature 20-40℃, time 2-12 hours; Preferably, the activation conditions include: under vacuum conditions, at a temperature of 60-120°C, for a time of 2-12 hours.

8. The preparation method according to claim 7, characterized in that, The carbon nanotube pretreatment is selected from at least one of acidification treatment, heat treatment and cleaning treatment; Preferably, the acidification treatment includes: placing the carbon nanotubes in an acid solution for ultrasonic treatment, followed by washing and drying; more preferably, the acid solution is nitric acid with a mass concentration of 30%-60% and / or sulfuric acid with a mass concentration of 20%-40%, and even more preferably, the volume ratio of nitric acid to sulfuric acid is 1:2-4; Preferably, the heat treatment includes: placing the carbon nanotubes at 300-500°C for 1-3 hours; Preferably, the detergent used in the cleaning process is selected from at least one of acetone, diethyl ether, and n-hexane.

9. A method for capturing carbon from the air, characterized in that, The adsorbent for air carbon capture according to any one of claims 1-6 or the adsorbent for air carbon capture prepared by the preparation method according to claim 7 or 8 is brought into contact with an airflow containing carbon dioxide to adsorb carbon dioxide from the air. Preferably, the concentration of carbon dioxide in the airflow is 400-500 ppm; Preferably, the adsorbent for air carbon capture is regenerated by heat treatment; more preferably, the heat treatment temperature is 80-120°C; and / or, the heat treatment is performed in a vacuum environment.

10. An air carbon capture device, characterized in that, The device comprises an adsorbent for air carbon capture as described in any one of claims 1-6 or an adsorbent for air carbon capture prepared by the preparation method described in claim 7 or 8; preferably, the device is used to capture carbon dioxide generated by power plants, industrial production processes or transportation.