Nitrogen-doped carbon aerogel and preparation method and application thereof

Abstract

The application belongs to the technical field of preparation of carbon aerogel materials, and particularly relates to a nitrogen-doped carbon aerogel and a preparation method and application thereof. A carbon aerogel with a three-dimensionally interconnected microporous structure is prepared by using two precursors with low cost and rich in nitrogen content, namely acrylamide and aniline. Firstly, a three-dimensionally interconnected polyacrylamide medium with high absorbability is prepared; then, by virtue of the high absorbability, the reaction solution of aniline is fully absorbed in a low-temperature state, and the aniline is uniformly dispersed and orderly polymerized under a freezing condition, so that the problem of agglomeration of traditional polyaniline preparation and difficulty in dispersion are solved; finally, an activating agent is used to activate and pore-form the aerogel. The carbon aerogel has high nitrogen content, rich in a large number of basic active sites and a three-dimensionally interconnected microporous structure, and thus the CO2 adsorption capacity is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of preparation of carbon aerogel materials, and particularly relates to a nitrogen-doped carbon aerogel and a preparation method and application thereof. BACKGROUND

[0002] Carbon dioxide capture and storage (CCS) is an important technical path for reducing carbon emissions and addressing global warming. Among them, adsorption technology is attracting attention due to its high efficiency, especially when the adsorbent has a three-dimensional interconnected pore structure and can achieve rapid gas transmission, its application potential is more significant. Carbon aerogel shows a wide application prospect due to its high specific surface area, adjustable density, high porosity, flexible pore size distribution and excellent electrical conductivity. Compared with traditional carbon aerogel, nitrogen-doped carbon aerogel has more superior performance due to more active sites. After nitrogen atoms replace carbon atoms in carbon materials, the morphology, structure and chemical properties of the materials can be effectively controlled, and the reaction activity can be improved. In addition, the introduction of nitrogen heteroatoms can significantly enhance the basic active sites on the surface of carbon materials, thereby improving the adsorption capacity and selectivity of acidic CO2 molecules. By directly activating nitrogen-containing polymers, not only the complex post-processing steps can be avoided, but also the precise control of chemical composition can be achieved, further improving the adsorption performance. At the same time, this method can effectively alleviate the problem of blocking of active sites and diffusion channels caused by post-processing, thereby maintaining the high adsorption performance of the material.

[0003] A Chinese patent with application number 201510649028.2 (a nitrogen-doped carbon aerogel and a preparation method thereof) discloses a method for preparing a nitrogen-doped carbon aerogel, which process is to add resorcinol and formaldehyde solution in m-trihydroxybenzene solution, after stirring, add potassium carbonate to form an aerogel, after the aerogel is treated by acetone solvent exchange, an m-trihydroxybenzene-resorcinol-formaldehyde gel is prepared, through supercritical carbon dioxide extraction and drying steps, a xerogel is obtained, and finally a nitrogen-doped carbon aerogel is prepared by carbonization. A Chinese patent with application number 201711206128.3 (a method for preparing a nitrogen-doped carbon aerogel) proposes a preparation process using bean dregs as carbon source, the specific operation is to mix bean dregs with concentrated sulfuric acid and stir to form a carbon sol precursor, after dilution, a brown precipitate is obtained by microwave hydrothermal treatment; the precipitate is prepared into a nitrogen-doped carbon aerogel by suction filtration, drying and high-temperature carbonization; however, these preparation methods have complex process flow, require the use of professional equipment such as supercritical carbon dioxide extraction instrument, and take a long time. The raw material cost is expensive, including resorcinol and formaldehyde, etc. which are highly toxic chemicals. In addition, the structure of the prepared carbon aerogel is relatively single, which is difficult to meet the actual application requirements. Therefore, it is urgent to develop a new adsorbent with higher selectivity and adsorption efficiency to promote the efficient development of CO2 capture technology. SUMMARY

[0004] In view of this, the present application aims to provide a nitrogen-doped carbon aerogel and its preparation method and application.

[0005] The carbon aerogel uses a freezing crystallization and subsequent polymerization strategy to prepare a three-dimensionally interconnected carbon aerogel by using two low-cost and nitrogen-rich precursors, acrylamide (AM) and aniline (ANI). First, a three-dimensionally interconnected polyacrylamide (PAM) medium with high absorbability is prepared; then, by virtue of its high absorbability, the aniline reaction solution is fully absorbed in a low-temperature state (to ensure sufficient aniline reaction solution), and the aniline is uniformly dispersed and polymerized under the action of ice crystals in a frozen condition, thus solving the problem of agglomeration of traditional polyaniline (PANI) preparation. Finally, the aerogel is activated to form pores by using an activating agent. The carbon aerogel significantly improves the CO2 adsorption capacity due to its high nitrogen content, rich basic active sites and three-dimensionally interconnected microporous structure.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A preparation method of a nitrogen-doped carbon aerogel, comprising the following steps:

[0008] (1) Preparation of a PAM aerogel with high absorbability

[0009] Acrylamide (AM) and an N,N'-methylenebisacrylamide (MBA) crosslinking agent are dissolved in deionized water, and after nitrogen is filled to drive oxygen, stirring is performed until complete dissolution to form a uniform solution; pre-cooled ammonium persulfate (APS) and N,N,N',N'-tetramethyl ethylenediamine (TEMED) are added to the solution at-5 ~ 0℃; after uniform stirring, the solution is quickly poured into a silica gel mold, and freezing polymerization is performed at-40 ~-25℃; and then, after melting, washing and drying, a PAM aerogel with a three-dimensionally continuous pore structure and high absorbability is obtained;

[0010] To obtain a PAM aerogel with a three-dimensionally continuous pore structure and high absorbability, the present application uses a freezing crystallization polymerization method to realize copolymerization of an acrylamide monomer and an N,N'-methylenebisacrylamide (MBA) crosslinking agent in an aqueous solution;

[0011] (2) Uniform dispersion and polymerization of PANI

[0012] Aniline (ANI) is added dropwise into an acidic solution under a nitrogen atmosphere, stirred thoroughly to ensure complete dissolution, and then pre-cooled; ammonium persulfate (APS) is dissolved in deionized water using microwave-assisted ultrasonic and pre-cooled; when small ice crystals appear in the two pre-cooled solutions, the two pre-cooled solutions are quickly mixed and stirred thoroughly; then the pre-cooled PAM aerogel is added, and after mixing uniformly, the mixture is frozen and polymerized in an environment of -40 to -25℃, and then melted and dried; during the cooling and crystallization of the mixed solution, the solvent water crystallizes into a pore-forming agent and separates from the solute phase, the solute phase is continuously concentrated, which promotes the self-assembly of the ANI solute in the three-dimensionally interconnected PAM aerogel to complete the polymerization and spreading, and finally forms a polymer (PANI@PAM) aerogel;

[0013] (3) Activation and carbonization treatment

[0014] The PANI@PAM aerogel is thoroughly ground under nitrogen, and an activator is added and mixed uniformly; sufficient calcination and activation are performed at a certain heating rate under a flowing nitrogen (N2) atmosphere; and then the residual activator is removed by soaking in an acidic solution, and the nitrogen-doped carbon aerogel is obtained after complete washing and drying. The activation of the polymer can avoid the loss of active sites and retain the three-dimensionally interconnected pore structure of the PAM aerogel, providing a fast channel for the high-speed flow of CO2.

[0015] Preferably, in the reaction system in step (1), the mass-volume ratio of acrylamide (AM), N,N'-methylenebisacrylamide (MBA), and deionized water is (0.5 g ~ 1.3 g): (0.1 g ~ 0.2 g): (5 mL ~ 20 mL).

[0016] Further preferably, in step (1), the ammonium persulfate (APS) is added in the form of 0.3 mL ~ 0.6 mL of an APS aqueous solution with a mass fraction of 5% ~ 20%, and the N,N,N',N'-tetramethyl ethylenediamine (TEMED) is added in the form of 0.1 mL ~ 0.3 mL of a TEMED aqueous solution with a mass fraction of 5% ~ 15%.

[0017] Preferably, in step (1), the nitrogen-oxygen driving time is 2 ~ 4 h; the freezing polymerization is performed at -40 ~ -20℃ for 16 ~ 24 h; the melting temperature is 20 ~ 26℃; and the unreacted monomers are completely removed by ethanol ultrasonic cleaning and deionized water cleaning to neutralization.

[0018] Preferably, in step (2), the acidic solution is hydrochloric acid (HCl) or phytic acid (C6H 18 O 24P6) an aqueous solution of sulfuric acid (H2SO4) or nitric acid (HNO3), more preferably, the acidic solution is hydrochloric acid.

[0019] Preferably, the concentration of the acidic solution in step (2) is 1-3 mol / L, and the volume is 4-6 mL; the pre-cooling temperature is-10-0 ℃.

[0020] Preferably, in step (2), the volume of the aniline is 2-5 mL, and the concentration is >99.5%; the mass of ammonium persulfate is 1-2 g, and the volume is 1-2 mL; the mass of the PANI@PAM aerogel is 0.1-0.5 g; the freezing and polymerization time under-40--25 ℃ is 18-24 h; the melting temperature is 30-40 ℃; and the drying is performed in an oven at 40-50 ℃ for 12-18 h.

[0021] Preferably, in step (3), the activating agent is potassium carbonate (K2CO3), potassium hydroxide (KOH), or phosphoric acid (H3PO4), more preferably, the activating agent is K2CO3 or KOH.

[0022] Preferably, in step (3), the mass ratio of the activating agent to the PANI@PAM aerogel is (1-4):1.

[0023] Preferably, in step (3), the flow rate of the flowing nitrogen is 0.4-1 L / min; the heating rate of the calcination is 1-10 ℃ / min; the calcination temperature is 400-900 ℃; and the sufficient calcination and activation time is 2-4 h.

[0024] Preferably, in step (3), the acidic solution is hydrochloric acid (HCl), or an aqueous solution of nitric acid (HNO3), sulfuric acid (H2SO4), formic acid (HCOOH), acetic acid (CH3COOH), or oxalic acid (C2H2O4), more preferably, the acidic solution is hydrochloric acid.

[0025] Preferably, in step (3), the concentration of the acidic solution is 1-3 mol / L, and the soaking time is 4-6 h.

[0026] Preferably, in step (3), the washing is performed by ultrasonic cleaning with ethanol and cleaning with deionized water until neutral; and the drying is performed in an oven at 90-150 ℃ for 10-12 h.

[0027] The nitrogen-doped carbon aerogel prepared by the above method.

[0028] Use of the nitrogen-doped aerogel in CO2 adsorption.

[0029] Advantages

[0030] The present application constructs a hierarchical carbon aerogel adsorbent with a spatial three-dimensional continuous nitrogen-rich structure (about 10%) and a pore wall with a rich micro-pore structure (0.4-0.9 nm) by a freezing crystallization polymerization and activation technology. From a molecular level, the essence of the substrate of the adsorbent described in the present application is a three-dimensional network of a high-absorbing, highly interconnected pore structure polymer chain, which provides a good place for the reaction of an aniline mixed solution. When the aniline solution enters the three-dimensional network, the water solution is crystallized to form a pore-forming agent due to rapid cooling, the solute aniline is highly enriched and covers the surface of the three-dimensional network under the action of ice crystals, and polymerization extension is carried out under the action of an initiator to complete self-assembly. The freezing crystallization polymerization method can break the strong hydrogen bonding effect of aniline during polymerization, thereby improving the coverage of aniline in the material and the nitrogen content of the polymer. Under the action of an activating agent, a large number of micro-pore structures are generated on the surface of the polymer, greatly improving the specific surface area of the material. The specific surface area of the prepared carbon aerogel material is 200-1500 m 2 / g, and the CO2 adsorption capacity is 0.55-4.5 mmol / g. The material has good stability and can maintain more than 95% of the initial adsorption capacity after 10 adsorption-desorption cycles.

[0031] The present application uses aniline and acrylamide, which are low in price and high in nitrogen content, as a carbon source, adopts a preparation strategy combining freezing crystallization polymerization and high-temperature carbonization, and has a simple process and is suitable for large-scale industrial production. The obtained product has the characteristics of rich nitrogen content, reasonable pore grading, high specific surface area, and stable structure, and can be widely applied in the field of high-efficiency CO2 adsorption. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a preparation flowchart of the nitrogen-doped carbon aerogel of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described in conjunction with specific examples. The advantages and characteristics of the present application will be more clearly embodied in the description. However, the examples are only used as a demonstration and do not constitute any limitation on the scope of the present application. Those skilled in the art should understand that the details and forms of the technical solutions can be modified or replaced without departing from the spirit and scope of the present application, and these modifications and replacements all belong to the protection scope of the present application.

[0034] Example 1

[0035] A preparation method of a nitrogen-doped carbon aerogel, comprising the following steps:

[0036] (1) 0.9 g of acrylamide (AM) monomer and 0.18 g of N,N'-methylenebisacrylamide (MBA) crosslinking agent were added to 10 mL of deionized water, and nitrogen was used to remove oxygen for 3 h. The mixture was stirred until it was completely dissolved to form a uniform solution. When the temperature dropped to -5°C, 0.4 mL of pre-cooled 10% ammonium persulfate (APS) aqueous solution and 0.2 mL of 10% N,N,N',N'-tetramethyl ethylenediamine (TEMED) aqueous solution were added to the solution. After stirring, the mixture was quickly poured into a silica gel mold (size: length x width x height = 60 mm x 30 mm x 40 mm) and placed in a freezer at -20°C for 24 h. After the end of the reaction, the ice crystals were melted at room temperature, washed with deionized water, and dried at ambient pressure to obtain PAM aerogel.

[0037] (2) A 4.75 mL solution of 3 mol / L HCl was prepared and slowly added to 2 mL of aniline (ANI), which was stirred thoroughly to ensure complete dissolution and cooled to -10°C. In another beaker, 1.3 g of APS was dissolved in 2 mL of deionized water using an ultrasonic vibrator, and the solution was pre-cooled. When small ice crystals appeared in the pre-cooled solution, the two cooled solutions were quickly mixed and stirred thoroughly. Subsequently, 0.2 g of pre-cooled PAM aerogel was added, and the mixture was placed in a freezer at -30°C for 24 h. After the reaction was completed, the mixture was melted in deionized water at 35°C, and the resulting product was dried in an oven at 50°C for 12-18 h to obtain PANI@PAM 3D porous structure aerogel.

[0038] (3) The obtained aerogel material was ground into powder and mixed with an activating agent (K2CO3) in a mortar at a mass ratio of 1:2. Then, the mixture was placed in a tube furnace and calcined under a flowing nitrogen (N2) atmosphere at a flow rate of 0.5 L / min, with a heating rate of 5°C / min and a calcination temperature of 650°C for 2 h. After activation, the material was soaked in a 1 mol / L HCl solution for 5 h to remove residual activating agents. Subsequently, the material was washed repeatedly with deionized water and ethanol solution until it was neutral, and finally dried at 95°C for 12 h.

[0039] The specific surface area of the carbon aerogel adsorbent prepared in Example 1 was 1354.63 m 2 / g, and the micropore volume was 0.60 cm 3The micropores are distributed in the range of 0.55-0.76 nm, and the carbon aerogel has good CO2 affinity. The carbon aerogel prepared by the reaction system formulation in Example 1 has a CO2 saturated adsorption capacity of 4.32 mmol / g at 25°C and 101 kPa, which is increased by 89.76% compared with the adsorption capacity without adding the activator. After 10 adsorption-desorption cycles, the adsorption capacity of the adsorbent is still as high as 95% of the initial adsorption capacity.

[0040] Example 2

[0041] A preparation method of a nitrogen-doped carbon aerogel, comprising the following steps:

[0042] (1) 1.0 g of acrylamide (AM) monomer and 0.18 g of N,N'-methylenebisacrylamide (MBA) crosslinking agent were added to 20 mL of deionized water, and the solution was stirred for 3 h under nitrogen atmosphere to remove oxygen until the solution was completely dissolved to form a uniform solution. When the temperature dropped to -5°C, 0.3 mL of pre-cooled 10% ammonium persulfate (APS) and 0.3 mL of 10% N,N,N',N'-tetramethyl ethylenediamine (TEMED) were added to the solution. After stirring, the solution was quickly poured into a silica gel mold (size: length x width x height = 60 mm x 30 mm x 40 mm), and the mold was placed in a freezer at -20°C for 24 h. After the end of the reaction, the ice crystals were melted at room temperature, washed with deionized water, and dried at ambient pressure to obtain a PAM aerogel.

[0043] (2) 4.75 mL of 1.5 mol / L phytic acid solution was prepared and slowly added to 2 mL of aniline (ANI), and the solution was stirred to ensure complete dissolution and cooled to -10°C. In another beaker, 1.5 g of APS was dissolved in 2 mL of deionized water with an ultrasonic vibrator, and the solution was pre-cooled. When small ice crystals appeared in the pre-cooled solution, the two cooled solutions were quickly mixed and stirred thoroughly. Subsequently, 0.2 g of pre-cooled PAM aerogel was added, and the mixture was placed in a freezer at -30°C for 24 h. After the reaction was completed, the product was melted in deionized water at 35°C, and the resulting product was dried in an oven at 50°C for 12-18 h to obtain a PANI@PAM 3D porous structure aerogel.

[0044] (3) The obtained aerogel material was ground into powder and uniformly mixed with an activating agent (KOH) in a mortar at a mass ratio of 1:2. Then, the mixture was placed in a tube furnace for calcination and activation under a flowing nitrogen (N2) atmosphere at 0.5 L / min, with a heating rate of 10°C / min, a calcination temperature of 750°C and a holding time of 2 h. After activation, the material was soaked in a 1 mol / L HC1 solution for 5 h to remove residual activating agent. Subsequently, the material was repeatedly washed with deionized water and an ethanol solution until neutral, and finally dried at 95°C for 12 h.

[0045] The specific surface area of the carbon aerogel adsorbent prepared in this Example 2 was 1175.67 m 2 / g, the micropore volume was 0.36 cm 3 / g, the micropore distribution was in the range of 0.45 ~ 0.70 nm, and the carbon aerogel adsorbent had good CO2 affinity. The CO2 saturated adsorption capacity of the carbon aerogel adsorbent prepared in this Example 2 was 3.81 mmol / g at 25°C and 101 kPa, which was increased by 85.56% compared with the adsorption capacity without adding an activating agent.

[0046] Example 3

[0047] A method for preparing a nitrogen-doped carbon aerogel, comprising the following steps:

[0048] (1) 0.5 g of acrylamide (AM) monomer and 0.2 g of N,N'-methylenebisacrylamide (MBA) crosslinking agent were added to 10 mL of deionized water, and the solution was stirred under nitrogen for 3 h until the monomers were completely dissolved to form a uniform solution. When the temperature dropped to -5°C, 0.5 mL of pre-cooled 15% ammonium persulfate (APS) and 0.3 mL of 15% N,N,N',N'-tetramethyl ethylenediamine (TEMED) were added to the solution. After stirring uniformly, the solution was quickly poured into a silica gel mold (size: length x width x height = 60 mm x 30 mm x 40 mm) and placed in a freezer at -20°C for 24 h of cold polymerization. After the end of the polymerization, the ice crystals were melted at room temperature, washed with deionized water and dried under ambient atmospheric pressure to obtain a PAM aerogel.

[0049] (2) Prepare 5 mL of 1.5 mol / L HCl solution, slowly add it to 2 mL of aniline (ANI), and stir well to ensure complete dissolution and cool to -10°C. In another beaker, add 2.0 g of APS, and pre-cool the solution after dissolving in 2 mL of deionized water with an ultrasonic vibrator. When small ice crystals appear in the pre-cooled solution, quickly mix the two cooled solutions and stir well. Then, add 0.2 g of pre-cooled PAM aerogel, mix well, and then place the mixture in a freezer at -30°C for 24 h. After the reaction is complete, melt in deionized water at 35°C, and dry the resulting product in an oven at 50°C for 12-18 h to obtain PANI@PAM 3D porous structure aerogel.

[0050] (3) The obtained aerogel material is ground into powder and uniformly mixed with an activating agent (KOH) in a mortar at a mass ratio of 1:4. Then, the mixture is placed in a tube furnace for calcination and activation under a flowing nitrogen (N2) atmosphere at 1 L / min, with a heating rate of 4°C / min, a calcination temperature of 850°C and a holding time of 1 h. After activation is complete, soak in a 1 mol / L HCl solution for 5 h to remove residual activating agent. Then, wash repeatedly with deionized water and ethanol solution until neutral, and finally dry at 95°C for 12 h.

[0051] The specific surface area of the carbon aerogel adsorbent prepared in this Example 3 is 324.34 m 2 / g, the micropore volume is 0.22 cm 3 / g, the micropore distribution is in the range of 0.72-0.93 nm, and it has good CO2 affinity. The carbon aerogel adsorbent prepared in the reaction system formulation of Example 3 has a CO2 saturated adsorption capacity of 0.97 mmol / g at 25°C and 101 kPa, which is 43.30% higher than the adsorption capacity without adding an activating agent.

[0052] Comparative Example 1

[0053] A method for preparing a nitrogen-doped carbon aerogel, comprising the following steps:

[0054] (1) 0.9 g of acrylamide (AM) monomer and 0.18 g of N,N'-methylenebisacrylamide (MBA) crosslinking agent were added to 10 mL of deionized water, and nitrogen was used to remove oxygen for 3 h. The mixture was stirred until it was completely dissolved to form a uniform solution. When the temperature dropped to -5°C, 0.4 mL of pre-cooled 10% ammonium persulfate (APS) and 0.2 mL of 10% N,N,N',N'-tetramethyl ethylenediamine (TEMED) were added to the solution. After stirring, the mixture was quickly poured into a silica gel mold (size: length x width x height = 60 mm x 30 mm x 40 mm) and placed in a freezer at -20°C for 24 h. After the end of the reaction, the ice crystals were melted at room temperature, washed with deionized water, and dried at ambient pressure to obtain a PAM aerogel.

[0055] (2) A 4.75 mL solution of 3 mol / L HCl was prepared and slowly added to 2 mL of aniline (ANI), which was stirred thoroughly to ensure complete dissolution and cooled to -10°C. In another beaker, 1.3 g of APS was dissolved in 2 mL of deionized water using an ultrasonic vibrator, and the solution was pre-cooled. When small ice crystals appeared in the pre-cooled solution, the two cooled solutions were quickly mixed and stirred thoroughly. Subsequently, 0.2 g of pre-cooled PAM aerogel was added, and the mixture was placed in a freezer at -30°C for 24 h. After the reaction was completed, the mixture was melted in deionized water at 35°C, and the resulting product was dried in an oven at 50°C to obtain a PANI@PAM 3D porous structure aerogel.

[0056] (3) The obtained aerogel material was ground into powder and placed in a tube furnace for calcination under a flowing nitrogen (N2) atmosphere at 0.5 L / min, with a heating rate of 5°C / min and a calcination temperature of 650°C for 2 h. After calcination, the material was soaked in a 1 mol / L HCl solution for 5 h. Subsequently, the material was washed repeatedly with deionized water and ethanol solution until it was neutral, and finally dried at 95°C for 12 h.

[0057] The specific surface area of the carbon aerogel adsorbent prepared in Comparative Example 1 was 1.56 m 2 / g, the micropore volume was 0.03 cm 3 / g, and the CO2 saturated adsorption capacity at 25°C and 101 kPa was 0.55 mmol / g.

Claims

1. A method for preparing a nitrogen-doped carbon aerogel, characterized by, Comprising the following steps: (1) Preparation of high-absorbent PAM aerogel Dissolve acrylamide and N,N'-methylene bisacrylamide crosslinking agent in deionized water, and after nitrogen filling to drive oxygen, stir until completely dissolved to form a uniform solution; add pre-cooled ammonium persulfate and N,N,N',N'-tetramethyl ethylenediamine to the solution at -5 ~ 0℃; after stirring evenly, quickly pour into silica gel mold, and freeze polymerize at -40 ~ -25℃; then melt, wash and dry to obtain PAM aerogel with high absorbency and three-dimensional continuous channel structure; (2) Uniform dispersion and polymerization of PANI Drop aniline into the acidic solution under a nitrogen atmosphere, stir thoroughly to ensure complete dissolution, and then pre-cool; Dissolve ammonium persulfate in deionized water using microwave-assisted ultrasonic and pre-cool; when small ice crystals appear in the two pre-cooled solutions, quickly mix the two pre-cooled solutions and stir thoroughly; then add pre-cooled PAM aerogel, mix evenly, and then place the mixture in a -40 ~ -25℃ environment for freeze polymerization, and then melt and dry; finally form polymer PANI@PAM aerogel; (3) Activation and carbonization treatment Grind the PANI@PAM aerogel thoroughly under nitrogen, and add an activator and mix evenly; fully calcine and activate at a certain heating rate under a flowing nitrogen atmosphere; then soak in an acidic solution to remove residual activator, and wash and dry completely to obtain the nitrogen-doped carbon aerogel.

2. The method for preparing nitrogen-doped carbon aerogel according to claim 1, characterized in that, In the reaction system in step (1), the mass-volume ratio of acrylamide, N,N'-methylene bisacrylamide, and deionized water is (0.5 g ~ 1.3 g): (0.1 g ~ 0.2 g): (5 mL ~ 20 mL).

3. The method for preparing nitrogen-doped carbon aerogel according to claim 1, characterized by, In step (1), the ammonium persulfate is added in the form of 0.3 mL ~ 0.6 mL of a 5% ~ 20% APS aqueous solution, and the N,N,N',N'-tetramethyl ethylenediamine is added in the form of 0.1 mL ~ 0.3 mL of a 5% ~ 15% TEMED aqueous solution.

4. The method for preparing nitrogen-doped carbon aerogel according to claim 1, characterized by, In step (1), the nitrogen filling and oxygen driving time is 2 ~ 4 h; the freeze polymerization is carried out at -40 ~ -20℃ for 16 ~ 24 h; the melting temperature is 20 ~ 26℃; and the washing is carried out using ethanol ultrasonic cleaning and deionized water cleaning until neutral, completely removing the unreacted monomers.

5. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by the steps of: In step (2), the acidic solution is hydrochloric acid, or an aqueous solution of phytic acid, sulfuric acid or nitric acid.

6. The method of claim 5, wherein the nitrogen-doped carbon aerogel is prepared by a process comprising: The acidic solution is hydrochloric acid.

7. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by the steps of: In step (2), the concentration of the acidic solution is 1 ~ 3 mol / L, and the volume is 4 ~ 6 mL; the pre-cooling temperature is -10 ~ 0℃.

8. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by the steps of: The volume of the aniline in step (2) is 2-5 mL, and the concentration is >99.5%; the mass of ammonium persulfate is 1-2 g, and the volume is 1-2 mL; the mass of PAM aerogel is 0.1-0.5 g; the freezing and polymerization time under the environment of-40 to-25℃ is 18-24 h; the melting temperature is 30-40℃; and the drying is performed in an oven at 40-50℃ for 12-18 h.

9. The method for preparing nitrogen-doped carbon aerogel according to claim 1, characterized in that, The activating agent in step (3) is potassium carbonate, potassium hydroxide or phosphoric acid.

10. The method for preparing nitrogen-doped carbon aerogel according to claim 9, characterized in that, The activating agent is K2CO3 or KOH.

11. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by the steps of: The mass ratio of the activating agent to PANI@PAM aerogel in step (3) is (1-4):

1.

12. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by a process comprising: The flow rate of the flowing nitrogen in step (3) is 0.4-1 L / min; the temperature rising rate of the calcination is 1-10℃ / min, the calcination temperature is 400-900℃, and the sufficient calcination and activation time is 2-4 h.

13. The method for preparing nitrogen-doped carbon aerogel according to claim 1, characterized in that, The acid solution in step (3) is hydrochloric acid, or an aqueous solution of nitric acid, sulfuric acid, formic acid, acetic acid or oxalic acid.

14. The method of claim 13, wherein the nitrogen-doped carbon aerogel is prepared by a process comprising: The acid solution is hydrochloric acid.

15. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by a process comprising: The concentration of the acid solution in step (3) is 1-3 mol / L, and the soaking time is 4-6 h.

16. The method of claim 1, wherein the nitrogen-doped carbon aerogel is prepared by a process comprising: The washing in step (3) adopts ethanol ultrasonic cleaning and deionized water cleaning until neutral; and the drying is performed in an oven at 90-150℃ for 10-12 h.

17. The nitrogen-doped carbon aerogel prepared by the preparation method according to any one of claims 1-16.

18. The nitrogen-doped carbon aerogel according to claim 17 for use in CO2 adsorption.

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