Ordered multi-stage functionalized wood carbon aerogel as well as preparation method and application thereof

Abstract

The invention relates to the technical field of CO2 adsorption materials, and discloses ordered multi-stage functionalized wood carbon aerogel as well as a preparation method and application thereof. The method comprises the following steps: S1, carrying out delignification treatment on balsa wood chips, cleaning, freezing and drying to obtain wood aerogel; s2, soaking the wood aerogel in an ammonium sulfate solution; s3, placing the impregnated aerogel in a tubular furnace, and carrying out heating carbonization under nitrogen to prepare carbon aerogel; s4, grinding the carbon aerogel and potassium hydroxide, heating and activating under nitrogen, cleaning and drying to obtain porous carbon; s5, adding the porous carbon into the modified solution, performing ultrasonic treatment, standing and dipping, and then washing and drying to obtain a finished product. According to the invention, wood carbon aerogel is constructed by utilizing the dual flame-retardant effects of cellulose and ammonium sulfate and a chemical activation method, and amino is introduced for modification, so that the ordered multi-stage functionalized wood porous carbon is prepared and is used for rapidly adsorbing CO2.

Description

Technical Field

[0001] This invention relates to the field of CO2 adsorption materials technology, and in particular to an ordered multi-level functionalized lignocarbon aerogel, its preparation method, and its application. Background Technology

[0002] The extensive use of fossil fuels has led to a sharp rise in atmospheric CO2 concentration, triggering the greenhouse effect and global climate change. Carbon capture, utilization, and storage (CCUS) technology is one of the effective means to mitigate this problem, and solid adsorbents have become a research hotspot due to their advantages such as high adsorption capacity, renewability, and ease of operation.

[0003] In existing technologies, biomass-derived porous carbon materials are used for CO2 adsorption due to their wide availability and low cost, but the following problems still exist:

[0004] (1) The vertical pores of wood are prone to collapse during the traditional carbonization process, resulting in a decrease in specific surface area;

[0005] (2) Unfunctionalized porous carbon has limited chemical adsorption capacity for CO2;

[0006] (3) The adsorption rate and capacity need to be further improved to meet the needs of practical applications.

[0007] Balsa wood is an ideal biotemplate due to its rapid growth, lightweight nature, and unique porous structure. However, structural shrinkage and pore collapse during its carbonization process limit its performance. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide an ordered multi-level functionalized lignocarbon aerogel, its preparation method, and its application. The lignocarbon aerogel prepared by this invention, through delignification, ammonium sulfate flame retardancy, KOH activation, and TEPA amino modification, solves the problems of pore collapse and insufficient adsorption performance in the prior art, achieving efficient and rapid CO2 adsorption.

[0009] The technical solution adopted by this invention to solve its technical problem is:

[0010] A method for preparing ordered, multi-level functionalized lignocarbon aerogels, specifically including the following steps:

[0011] Step S1: Preparation of wood aerogel: Balsa wood chips are dried at 80-105℃ for 10-15 hours to constant weight, then subjected to delignification treatment, washed with deionized water and freeze-dried to obtain wood aerogel.

[0012] Step S2, Ammonium sulfate impregnation: The wood aerogel obtained in step S1 is impregnated in an ammonium sulfate solution;

[0013] Step S3, Preparation of carbon aerogel (CWAN): The impregnated aerogel is placed in a tube furnace and heated to 700-800℃ for 2 hours under a nitrogen atmosphere to obtain carbon aerogel.

[0014] Step S4, Preparation of porous carbon (KCWAN): The carbon aerogel obtained in step S3 is ground evenly with potassium hydroxide, then activated at 750-800℃ for 1-2 hours under a nitrogen atmosphere, washed with hydrochloric acid and distilled water and dried to obtain porous carbon.

[0015] Step S5, Amine Modification: The porous carbon obtained in step S4 is added to the modification solution, ultrasonically treated for 0.5-1 h, allowed to stand and impregnate for 4-6 h, and then washed and dried to obtain the finished ordered multi-level functionalized wood carbon aerogel (KCWANT).

[0016] Further, in step S1, the lignin removal operation specifically involves immersing balsa wood chips in a solution containing 22.5 wt% sodium chlorite, adjusting the pH to 4.5–4.8 by adding glacial acetic acid, and then maintaining the solution at 60–80°C for 6–10 hours. Excessive lignin removal time can lead to cellulose breakage and reorganization, resulting in a low specific surface area of ​​the material after carbonization. By controlling the removal time, lignin can be effectively removed while preserving cellulose.

[0017] Furthermore, in step S2, the concentration of the ammonium sulfate solution is 0.05–0.1 mol / L, and the soaking time is 3–6 days, every 24 hours.

[0018] Furthermore, in steps S3 and S4, the heating rates are 2 to 5 °C / min, respectively.

[0019] Furthermore, in step S4, the mass ratio of carbon aerogel to potassium hydroxide is 1:(1-2).

[0020] Further, in step S5, the modified solution is a tetraethylenepentamine-methanol solution, which is prepared by adding tetraethylenepentamine (TEPA) to methanol and mixing them evenly, with the volume ratio of tetraethylenepentamine to methanol being 1:(200-250).

[0021] Furthermore, in step S5, the ratio of porous carbon to modified solution material is 1:1.

[0022] An ordered, multi-level functionalized lignocarbon aerogel was prepared using the method described above.

[0023] Furthermore, the lignocarbon aerogel has a vertical channel structure and a microporous-mesoporous hierarchical pore structure, with a specific surface area ≥600m². 2 / g, nitrogen content ≥5at%.

[0024] An application of the above-mentioned ordered multi-level functionalized lignocarbon aerogel, wherein the lignocarbon aerogel is used for CO2 adsorption.

[0025] The beneficial effects of this invention are as follows: This invention has a reasonable design and a simple preparation method, and has the following advantages:

[0026] (1) By removing lignin from wood and preserving cellulose, stable microchannels can be formed, which is conducive to the diffusion of CO2 in the material.

[0027] (2) By impregnating with ammonium sulfate, the flame retardancy of ammonium sulfate can effectively inhibit the structural collapse of balsa wood during the carbonization process and protect its vertical pore structure; ammonium sulfate can also be used as a source of nitrogen doping, increasing the nitrogen content of porous carbon, which is beneficial for CO2 adsorption.

[0028] (3) Using potassium hydroxide as an activator, by controlling the ratio and activation temperature, a well-developed porous structure is formed on the surface of the material, which increases the amount of micropores and the specific surface area of ​​the material, which is beneficial to the adsorption of CO2.

[0029] (4) Tetraethylenepentamine was used to modify porous carbon, and ultrasound was used to better introduce it into the porous carbon; introducing amino groups into the surface of porous carbon enhanced the chemical interaction with CO2 molecules, thereby improving the adsorption capacity.

[0030] (5) Balsa wood has ordered vertical channels after lignin removal. By activating micropores and introducing amino groups, the adsorption rate of CO2 by the material is effectively improved. The corresponding adsorption rate constant K of KCWANT is 1.4 times higher than that of unmodified CWA. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 The image shows the scanning electron microscope (SEM) morphology of the wood-based carbon aerogel prepared in Example 1.

[0033] Figure 2 The nitrogen adsorption-desorption isotherm of the wood-based carbon aerogel prepared in Example 1 is shown below.

[0034] Figure 3 Fourier transform infrared spectrum of the wood-based carbon aerogel prepared in Example 1;

[0035] Figure 4The X-ray photoelectron spectrum of the wood-based carbon aerogel prepared in Example 1 is shown below.

[0036] Figure 5 The adsorption kinetics of CO2 on the wood-based carbon aerogel prepared in Example 1 is shown in the figure.

[0037] Figure 6 The image shows the scanning electron microscope (SEM) morphology of the wood-based carbon aerogel prepared in Comparative Example 1. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] A method for preparing ordered, multi-level functionalized lignocarbon aerogels, specifically including the following steps:

[0042] Step S1: Preparation of wood aerogel: Balsa wood chips are dried at 80-105℃ for 10-15 hours to constant weight, then subjected to delignification treatment, washed with deionized water and freeze-dried to obtain wood aerogel.

[0043] Step S2, Ammonium sulfate impregnation: The wood aerogel obtained in step S1 is impregnated in an ammonium sulfate solution;

[0044] Step S3, Preparation of carbon aerogel: The impregnated aerogel is placed in a tube furnace and heated to 700-800℃ for 2 hours under a nitrogen atmosphere to obtain carbon aerogel.

[0045] Step S4, Preparation of porous carbon: The carbon aerogel obtained in step S3 is ground evenly with potassium hydroxide, then activated at 750-800℃ for 1-2 hours under a nitrogen atmosphere, washed with hydrochloric acid and distilled water and dried to obtain porous carbon.

[0046] Step S5, Amine Modification: The porous carbon obtained in step S4 is added to the modification solution, ultrasonically treated for 0.5-1h, allowed to stand and soak for 4-6h, then washed and dried to obtain the finished ordered multi-level functionalized lignocarbon aerogel.

[0047] In step S1, the delignification process specifically involves immersing balsa wood chips in a solution containing 2.5 wt% sodium chlorite, adjusting the pH to 4.5–4.8 by adding glacial acetic acid, and then maintaining the solution at 60–80°C for 6–10 hours.

[0048] In step S2, the concentration of the ammonium sulfate solution is 0.05–0.1 mol / L, the soaking time is 3–6 days, and the solution is changed every 24 hours.

[0049] In steps S3 and S4, the heating rates are 2–5 °C / min, respectively.

[0050] In step S4, the mass ratio of carbon aerogel to potassium hydroxide is 1:(1-2).

[0051] In step S5, the modified solution is a tetraethylenepentamine-methanol solution, which is prepared by adding tetraethylenepentamine to methanol and mixing them evenly, with the volume ratio of tetraethylenepentamine to methanol being 1:(200-250).

[0052] In step S5, the ratio of porous carbon to modified solution material is 1:1.

[0053] An ordered, multi-level functionalized lignocarbon aerogel was prepared using the above-described method; the prepared lignocarbon aerogel possesses a vertical channel structure and a microporous-mesoporous hierarchical pore structure, with a specific surface area ≥600 m². 2 / g, nitrogen content ≥5at%.

[0054] An application of the above-mentioned ordered multi-level functionalized lignocarbon aerogel, which is used for CO2 adsorption.

[0055] Example 1

[0056] A method for preparing ordered, multi-level functionalized lignocarbon aerogel (KCWANT):

[0057] Step S1: Dry the balsa wood at 105℃ for 12 hours. After drying to constant weight, immerse it in a solution containing 2.5wt% sodium chlorite. Adjust the pH of the solution to 4.6 by adding glacial acetic acid. Then, maintain the solution at 80℃ for 10 hours for delignin treatment. After cooling to room temperature, wash it several times with deionized water. After freeze-drying for 24 hours, obtain the delignin-free wood WA.

[0058] Step S2: Soak WA in ammonium sulfate solution (0.1 mol / L) for 3 days, changing the solvent daily. Wash with deionized water and dry to obtain aerogel.

[0059] Step S3: Transfer the prepared aerogel to a tube furnace and raise the temperature of the tube furnace to 800°C in a nitrogen atmosphere (80 mL / min) at a heating rate of 5°C / min, and keep it at this temperature for 2 hours to prepare carbon aerogel (CWAN).

[0060] In step S4, CWAN and KOH are ground in a 1:2 ratio. The mixture is then transferred to a nitrogen environment and heated to 750°C at a heating rate of 5°C / min and held for 2 hours to achieve activation. The mixture is named KCWAN.

[0061] Step S5: After cooling, the sample is washed sequentially with 1 mol / L hydrochloric acid solution and distilled water, and then dried at 60°C. TEPA and methanol are mixed at a volume ratio of 1:250 and KCWAN is added. The mixture is ultrasonically treated for 1 h to ensure uniform dispersion, and then allowed to stand for 4 h for soaking. After washing, it is placed in an oven and dried at 70°C to obtain an ordered multi-level functionalized lignocarbon aerogel, denoted as KCWANT-1.

[0062] Figure 1 The image shows the scanning electron microscope (SEM) morphology of the wood-based carbon aerogel prepared in Example 1. Figure 1 The microstructure of the prepared wood char aerogel was studied using scanning electron microscopy. Figure 1 The results showed that the honeycomb structure of Balsa wood WA after lignin removal remained intact, the tubular channels were well connected, and no collapse, shrinkage or cracking occurred. Figure 1 b shows that WA exhibits a loose, layered structure in the open channels along the growth direction. Figure 1 c shows that although the carbon walls of the carbon aerogel CWAN obtained by impregnation and carbonization with (NH4)2SO4 are thinner, it still has a layered structure similar to WA along the growth direction. This indicates that the addition of (NH4)2SO4 does not change the original structure of the material and protects its original structure during high-temperature calcination. Figure 1 d shows that CWAN exhibits a honeycomb structure in cross-section, but it has shrunk. Figure 1 As can be seen, there are many holes on the walls of the vertical channel. These holes are about 1-2 μm in size and are unique structures formed during the growth of trees.

[0063] Figure 2 The image shows the nitrogen adsorption-desorption isotherm of the wood-based carbon aerogel prepared in Example 1. Figure 2 As shown, compared with WCA, WCAN has a larger specific surface area (257.4 m²). 2 g -1This is because the material shrinks and collapses during carbonization, leading to a decrease in specific surface area. Introducing ammonium sulfate effectively inhibits this process, preserving a large amount of the carbonized structure and thus increasing the material's specific surface area. KCWAN's specific surface area is 632.6 m². 2 g -1 The results indicate that successful activation generated a large number of micropores, increasing the specific surface area of ​​WCAN. The specific surface area of ​​the material decreased slightly after TEPA impregnation, which may be due to the TEPA causing partial coverage of the micropores. The average pore size of the wood adsorbent is approximately 2-4 nm, indicating that the main components of the material are micropores and mesopores.

[0064] Figure 3 The Fourier transform infrared spectrum of the wood-based carbon aerogel prepared in Example 1 is shown. Figure 3 Showing FT-IR images of the lignocellulosic adsorbent. All FT-IR spectra show typical cellulose vibrational bands at 1736 and 1248 cm⁻¹. -1 The positions correspond to the -(C=O)- and -(C=O)-O- groups of lignin and hemicellulose, respectively. After delignification, compared with the original wood (NW), the strength of the lignin and hemicellulose groups in WA is significantly weakened or even disappeared, reflecting the high efficiency of the delignification process. At 3449 cm⁻¹ -1 The peak at 1369 cm⁻¹ corresponds to the tensile vibration of -OH. -1 The characteristic peak on the band indicates C=O tensile vibration, at 1384 cm⁻¹. -1 The peak value at 1410 cm⁻¹ corresponds to the tensile vibration of CN. Compared to other adsorbents, KCWANT shows better performance at 1410 cm⁻¹. -1 and 1570cm -1 The appearance of a new characteristic peak is caused by the symmetric and asymmetric bending vibrations of primary amine-NH2 in TEPA, indicating that TEPA has been successfully loaded onto the material surface.

[0065] Figure 4 The image shows the X-ray photoelectron spectrum of the wood-based carbon aerogel prepared in Example 1. Figure 4 As shown, the full-spectrum XPS spectra at 284.3, 397.9, and 532.25 eV clearly indicate the presence of C, N, and O elements in the material. A very small N1s peak appeared in CWA at 397.9 eV, indicating that a small amount of nitrogen remains in the wood biochar, derived from natural wood and retained during carbonization. Compared to CWA, an increase in nitrogen content was observed in CWAN, indicating that (NH4)2SO4 was successfully grafted onto the material surface after long-term impregnation, and N doping was achieved through high-temperature calcination, effectively increasing the N content of the material. After TEPA impregnation, KCWANT showed a significant N1s peak, indicating that TEPA was successfully loaded onto the wood biochar.

[0066] Figure 5 This is an adsorption kinetic diagram of CO2 on the wood-based carbon aerogel prepared in Example 1. Figure 5 As shown, at 25 °C, the maximum adsorption capacities of CWA, CWAN, KCWAN, and KCWANT were 4.06, 3.26, 2.43, 2.16, and 1.57 mmol g, respectively. -1 Among them, KCWANT had the largest adsorption capacity and the fastest adsorption rate. From Figure 5 It can be seen that CWA exhibits a relatively fast CO2 capture rate from 0 to 30 minutes, gradually decreases from 30 to 40 minutes, reaches a peak around 40 minutes, and then gradually reaches equilibrium. Figure 5 As can be seen from Figure d, the adsorption rate of the TEPA-modified carbon aerogel is significantly improved. KCWANT exhibits a rapid adsorption rate within 0-20 min, gradually decreasing from 20-25 min, and then leveling off after 30 min. This indicates that the introduction of TEPA, through chemical modification, enhances the material's adsorption capacity and significantly improves its adsorption rate.

[0067] Example 2

[0068] A method for preparing ordered, multi-level functionalized lignocarbon aerogel (KCWANT):

[0069] Step S1: Dry the balsa wood at 105℃ for 12 hours. After drying to constant weight, immerse it in a solution containing 2.5wt% sodium chlorite. Adjust the pH of the solution to 4.6 by adding glacial acetic acid. Then, maintain the solution at 80℃ for 6 hours for delignin treatment. After cooling to room temperature, wash it several times with deionized water. After freeze-drying for 24 hours, obtain the delignin-free wood WA.

[0070] Step S2: Soak WA in ammonium sulfate solution (0.1 mol / L) for 3 days, changing the solvent daily. Wash with deionized water and dry to obtain aerogel.

[0071] Step S3: Transfer the prepared aerogel to a tube furnace and raise the temperature of the tube furnace to 800°C in a nitrogen atmosphere (80 mL / min) at a heating rate of 5°C / min, and keep it at this temperature for 2 hours to prepare carbon aerogel (CWAN).

[0072] In step S4, CWAN and KOH are ground in a 1:2 ratio. The mixture is then transferred to a nitrogen environment and heated to 750°C at a heating rate of 5°C / min and held for 2 hours to achieve activation. The mixture is named KCWAN.

[0073] Step S5: After cooling, the sample is washed sequentially with 1 mol / L hydrochloric acid solution and distilled water, and then dried at 60°C. TEPA and methanol are mixed at a volume ratio of 1:250 and KCWAN is added. The mixture is ultrasonically treated for 1 h to ensure uniform dispersion, and then allowed to stand for 4 h for soaking. After washing, it is placed in an oven and dried at 70°C to obtain an ordered multi-level functionalized lignocarbon aerogel, denoted as KCWANT-2.

[0074] Example 3

[0075] A method for preparing ordered, multi-level functionalized lignocarbon aerogel (KCWANT):

[0076] Step S1: Dry the balsa wood at 105℃ for 12 hours. After drying to constant weight, immerse it in a solution containing 2.5wt% sodium chlorite. Adjust the pH of the solution to 4.6 by adding glacial acetic acid. Then, maintain the solution at 80℃ for 6 hours for delignin treatment. After cooling to room temperature, wash it several times with deionized water. After freeze-drying for 24 hours, obtain the delignin-free wood WA.

[0077] Step S2: Soak WA in ammonium sulfate solution (0.1 mol / L) for 3 days, changing the solvent daily. Wash with deionized water and dry to obtain aerogel.

[0078] Step S3: Transfer the prepared aerogel to a tube furnace and raise the temperature of the tube furnace to 800°C in a nitrogen atmosphere (80 mL / min) at a heating rate of 5°C / min, and keep it at this temperature for 2 hours to prepare carbon aerogel (CWAN).

[0079] In step S4, CWAN and KOH are ground in a 1:1 ratio, the mixture is transferred to a nitrogen environment, and activated by heating to 750°C at a heating rate of 5°C / min and holding for 2 hours. The mixture is named KCWAN.

[0080] Step S5: After cooling, the sample is washed sequentially with 1 mol / L hydrochloric acid solution and distilled water, and then dried at 60°C. TEPA and methanol are mixed at a volume ratio of 1:250 and KCWAN is added. The mixture is ultrasonically treated for 1 h to ensure uniform dispersion, and then allowed to stand for 4 h for soaking. After washing, it is placed in an oven and dried at 70°C to obtain an ordered multi-level functionalized lignocarbon aerogel, denoted as KCWANT-3.

[0081] Example 4

[0082] A method for preparing ordered, multi-level functionalized lignocarbon aerogel (KCWANT):

[0083] Step S1: Dry the balsa wood at 105℃ for 12 hours. After drying to constant weight, immerse it in a solution containing 2.5wt% sodium chlorite. Adjust the pH of the solution to 4.6 by adding glacial acetic acid. Then, maintain the solution at 80℃ for 6 hours for delignin treatment. After cooling to room temperature, wash it several times with deionized water. After freeze-drying for 24 hours, obtain the delignin-free wood WA.

[0084] Step S2: Soak WA in ammonium sulfate solution (0.1 mol / L) for 3 days, changing the solvent daily. Wash with deionized water and dry to obtain aerogel.

[0085] Step S3: Transfer the prepared aerogel to a tube furnace and raise the temperature of the tube furnace to 800°C in a nitrogen atmosphere (80 mL / min) at a heating rate of 5°C / min, and keep it at this temperature for 2 hours to prepare carbon aerogel (CWAN).

[0086] In step S4, CWAN and KOH are ground in a 1:2 ratio. The mixture is then transferred to a nitrogen environment and heated to 800℃ at a heating rate of 5℃ / min and held for 2 hours to achieve activation. The mixture is named KCWAN.

[0087] Step S5: After cooling, the sample is washed sequentially with 1 mol / L hydrochloric acid solution and distilled water, and then dried at 60°C. TEPA and methanol are mixed at a volume ratio of 1:250, and KCWAN is added and ultrasonically treated for 1 h to ensure uniform dispersion. Then, the sample is allowed to stand and soak for 4 h. After washing, it is placed in an oven and dried at 70°C to obtain an ordered multi-level functionalized lignocarbon aerogel, denoted as KCWANT-4.

[0088] Comparative Example 1

[0089] A method for preparing carbon aerogel (CWA):

[0090] Balsa wood was dried at 105℃ for 12 h until constant weight was achieved. It was then immersed in a solution containing 2.5 wt% sodium chlorite, and the pH of the solution was adjusted to 4.6 by adding glacial acetic acid. The wood was then kept at 80℃ for 6 h for delignin treatment. After cooling to room temperature, the wood was washed multiple times with deionized water and freeze-dried for 24 h to obtain delignin-free wood (WA). The prepared WA was transferred to a tube furnace and heated to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere (80 mL / min). The temperature was maintained at this temperature for 2 h to prepare carbon aerogel (CWA).

[0091] The scanning electron microscope (SEM) image of the lignocarbon aerogel prepared in this comparative example is shown below. Figure 6 As shown. Figure 6 It can be seen that the biochar CWA obtained by direct carbonization of WA shows that high-temperature calcination causes the layered structure of WA to collapse and the structure to become incomplete.

[0092] In summary, this invention utilizes the dual flame-retardant properties of cellulose and ammonium sulfate, along with chemical activation, to construct lignocarbon aerogels. Furthermore, it introduces amino modification to prepare ordered, multi-level functionalized porous lignocarbons for rapid CO2 adsorption.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ordered, multi-level functionalized lignocarbon aerogel, characterized in that: Specifically, the steps include the following: Step S1: Preparation of wood aerogel: Balsa wood chips are dried at 80-105℃ for 10-15 hours to constant weight, then subjected to delignification treatment, washed with deionized water and freeze-dried to obtain wood aerogel. Step S2, Ammonium sulfate impregnation: The wood aerogel obtained in step S1 is impregnated in an ammonium sulfate solution; Step S3, Preparation of carbon aerogel: The impregnated aerogel is placed in a tube furnace and heated to 700-800℃ for 2 hours under a nitrogen atmosphere to obtain carbon aerogel. Step S4, Preparation of porous carbon: The carbon aerogel obtained in step S3 is ground evenly with potassium hydroxide, then activated at 750-800℃ for 1-2 hours under a nitrogen atmosphere, washed with hydrochloric acid and distilled water and dried to obtain porous carbon. Step S5, Amino Modification: Add the porous carbon obtained in step S4 to the modification solution, sonicate for 0.5-1 h, let stand and impregnate for 4-6 h, then wash and dry to obtain the finished ordered multi-level functionalized lignocarbon aerogel.

2. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In step S1, the delignification process specifically involves immersing balsa wood chips in a solution containing 2.5 wt% sodium chlorite, adjusting the pH to 4.5–4.8 by adding glacial acetic acid, and then maintaining the solution at 60–80°C for 6–10 hours.

3. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In step S2, the concentration of the ammonium sulfate solution is 0.05–0.1 mol / L, the soaking time is 3–6 days, and the solution is replaced every 24 hours.

4. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In steps S3 and S4, the heating rates are 2 to 5 °C / min, respectively.

5. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In step S4, the mass ratio of carbon aerogel to potassium hydroxide is 1:(1-2).

6. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In step S5, the modified solution is a tetraethylenepentamine-methanol solution, which is prepared by adding tetraethylenepentamine to methanol and mixing them evenly, with the volume ratio of tetraethylenepentamine to methanol being 1:(200-250).

7. The method for preparing an ordered multi-level functionalized lignocarbon aerogel according to claim 1, characterized in that: In step S5, the ratio of porous carbon to modified solution material is 1:

1.

8. An ordered, multi-level functionalized lignocarbon aerogel, characterized in that: The wood-based carbon aerogel is prepared by the preparation method according to any one of claims 1 to 7.

9. The ordered multi-level functionalized lignocarbon aerogel according to claim 8, characterized in that: The wood-based carbon aerogel has a vertical channel structure and a microporous-mesoporous hierarchical pore structure, with a specific surface area ≥600 m². 2 / g, nitrogen content ≥5at%.

10. An application of the ordered multi-level functionalized lignocarbon aerogel as described in any one of claims 8 to 9, characterized in that: The wood-based carbon aerogel is used for CO2 adsorption.

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