Biomass-based carbon aerogel as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of carbon aerogel, and particularly relates to biomass-based carbon aerogel as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) crushing a biomass raw material, and uniformly mixing the crushed biomass raw material with an organic solvent to obtain a biomass liquefied liquid; (2) carrying out spray pyrolysis on the liquefied liquid to obtain biomass liquefied product microspheres; and (3) drying the biomass liquefied product microspheres, and carbonizing to obtain the biomass-based carbon aerogel. According to the method, renewable biomass resources are fully utilized, the cost is reduced, the environmental pollution is reduced, the prepared carbon aerogel has excellent physical and chemical properties, and the application field of the carbon aerogel is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon aerogels, and particularly relates to a biomass-based carbon aerogel and its preparation method and application. Background Art

[0002] As a material with characteristics such as high specific surface area, low density, good electrical conductivity and thermal stability, carbon aerogels are widely used in fields such as electrochemical energy storage, catalyst carriers, and adsorption materials. However, the preparation of traditional carbon aerogels mostly relies on fossil fuels, which not only increases costs but also is not conducive to environmental protection. Therefore, finding sustainable and low-cost biomass raw materials to prepare carbon aerogels has become the focus of research.

[0003] CN 108217624A discloses a preparation method of hierarchical porous carbon aerogels, including the following steps: freezing and freeze-drying a biomass material in sequence to obtain an aerogel; carbonizing the aerogel under a protective atmosphere to obtain a carbonized product; activating the carbonized product under an activation atmosphere to obtain hierarchical porous carbon aerogels. This technical solution has a complex process, with activation after carbonization, and there is still room for improvement.

[0004] CN 113559797A discloses a bio-carbon aerogel material, including biochar and lanthanum ions; the surface of the biochar contains hydroxyl groups and carboxyl groups; the lanthanum ions are bonded to the hydroxyl groups or carboxyl groups; the preparation method of the bio-carbon aerogel material includes the following steps: performing pyrolytic carbonization reaction on a biomass raw material to obtain biochar; placing the biochar in an aqueous solution of lanthanum salt for adsorption reaction and then freeze-drying to obtain the bio-carbon aerogel material. The biochar obtained by this technical solution retains the unique structure of biomass, and the surface contains a large number of hydroxyl groups and carboxyl groups, which can combine with lanthanum ions and improve the phosphorus adsorption performance of the material, but it cannot be applied to the field of new energy batteries.

[0005] Therefore, the prior art still requires a preparation method of carbon aerogels with a simple preparation process and reliable product quality. Summary of the Invention

[0006] The object of the present invention is to obtain a carbon aerogel with physical and chemical properties through spray pyrolysis and carbonization in view of the deficiencies of the existing carbon aerogel preparation methods, and to expand the application fields of carbon aerogels. The detailed technical solution of the present invention is as follows.

[0007] The present invention protects a preparation method of a biomass-based carbon aerogel, including the following steps:

[0008] (1) After crushing a biomass raw material, adding an organic solvent and mixing evenly to obtain a biomass liquefied liquid;

[0009] (2) Obtain biomass liquefied microspheres by spray pyrolysis of the liquefied liquid;

[0010] (3) Carbonize the biomass liquefied microspheres after drying to obtain biomass-based carbon aerogel.

[0011] Preferably, in step (1), an inorganic acid is further added. Specifically, after mixing the biomass powder and the solvent evenly, the inorganic acid is added and dissolved under acidic conditions.

[0012] Preferably, the solvent includes at least one of phenol and p-cresol, and the inorganic acid includes at least one of sulfuric acid, hydrochloric acid and nitric acid.

[0013] Preferably, the mass ratio of the biomass raw material to the solvent is 1:(2 - 10), and the mass ratio of the biomass raw material to the inorganic acid is 10:(1 - 2).

[0014] Preferably, the carbonization in step (3) is carried out under a protective atmosphere, the carbonization temperature is 650°C - 750°C, and the carbonization time is 2h - 3h.

[0015] Preferably, in step (2), the spray pyrolysis is to spray the biomass liquefied liquid into a calcination furnace through a sprayer to form light rice husk liquefied microspheres.

[0016] Preferably, the spray pressure is 0.1 - 1.5 MPa, the spray rate is 0.1 - 10 L / min, the inlet temperature is 200 - 600°C, the outlet temperature is 100 - 200°C, and the carrier gas flow rate is 10 - 100 m 3 / h.

[0017] Preferably, the biomass raw material includes any one of rice husk, corn straw and larch sawdust.

[0018] The present invention also protects a biomass-based carbon aerogel prepared by the preparation method described above.

[0019] The present invention also protects the application of the biomass-based carbon aerogel in electrochemical energy storage and pollutant adsorption.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The process of the present invention significantly increases the contact area between the biomass and the organic solvent, thereby greatly improving the conversion efficiency of the biomass to the liquefied liquid. Compared with the biomass raw material without pulverization treatment, this method can more quickly and completely dissolve and liquefy the biomass, and can also ensure the quality stability of the final product.

[0022] (2) The present invention is applicable to various combinations of biomass raw materials and organic solvents, overcoming the dependence limitations of traditional methods on specific types of biomass or solvents, broadening the effective utilization rate and application fields of biomass resources. The entire process conforms to the principles of green chemistry and helps to promote sustainable development. This process can not only improve production efficiency and reduce costs, but also further enhance economic benefits and social benefits due to the improvement of product quality and the reduction of waste emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a graph of the specific capacitance and specific surface area of the carbon aerogel electrode material of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further describes the specific embodiments of the present invention with reference to the drawings:

[0025] Example 1

[0026] 1. Clean the larch sawdust, dry it to a constant weight, and then crush it into fine powder.

[0027] 2. Mix the larch sawdust powder with isopropanol at a mass ratio of 1:2, add an appropriate amount of sulfuric acid (concentration: 7%, 10% of the larch mass), and stir and react at 30 °C for 2 h.

[0028] 3. After the reaction is completed, filter the mixture and wash it to neutral to obtain the larch liquefied product.

[0029] 4. Using the spray pyrolysis method, spray the larch liquefied product into the calcination furnace through a sprayer under the promotion and protection of nitrogen to form lightweight larch liquefied product microspheres.

[0030] 5. The dried microspheres are carbonized at 650 °C for 2 h under nitrogen protection to obtain carbon aerogel microspheres.

[0031] Example 2

[0032] 1. Clean the larch sawdust, dry it to a constant weight, and then crush it into fine powder.

[0033] 2. Mix the larch sawdust powder with isopropanol at a mass ratio of 1:1.5, add an appropriate amount of sulfuric acid (concentration: 7%, 8% of the larch mass), and stir and react at 40 °C for 3 h.

[0034] 3. After the reaction is completed, filter the mixture and wash it to neutral to obtain the larch liquefied product.

[0035] 4. Using the spray pyrolysis method, spray the larch liquefied product into the calcination furnace through a sprayer under the promotion and protection of argon to form lightweight larch liquefied product microspheres.

[0036] 5. The dried microspheres are carbonized at 700 °C for 2 h under nitrogen protection to obtain carbon aerogel microspheres.

[0037] Example 3

[0038] 1. Wash the rice husks clean, dry them to a constant weight, and then crush them into fine powder with a particle size less than 1 mm.

[0039] 2. Mix the pretreated rice husk powder with isopropanol at a mass ratio of 1:10. Add an appropriate amount of phosphoric acid (10% of the mass of the rice husks), and stir and react in a magnetic stirrer at 30 °C for 4 h for a liquefaction reaction to form a uniform suspension.

[0040] 3. After the reaction is completed, filter the mixture and wash it to neutral to obtain the rice husk liquefied product.

[0041] 4. Using spray pyrolysis, set the feed pump pressure to 1.5 MPa, the nozzle aperture to 0.5 mm. Set the inlet temperature to 400 °C, the outlet temperature to 150 °C, and the carrier gas flow rate to 50 m 3 / h. Under nitrogen protection, spray the rice husk liquefied liquid into the calcination furnace through a sprayer to form light rice husk liquefied product microspheres. Collect the generated microspheres and further dry them in an oven at 105 °C for 2 h to ensure complete removal of the residual solvent.

[0042] 5. Put the dried microspheres into a tube furnace and carbonize them at 750 °C for 2 h under nitrogen protection to obtain carbon aerogel microspheres.

[0043] Example 4

[0044] 1. Wash the corn straw clean, dry it to a constant weight, and then crush it into fine powder with a particle size less than 1 mm.

[0045] 2. Mix the pretreated corn straw powder with a mixed solvent of ethanol and isopropanol (mixed at 2:1) at a mass ratio of 1:8. Add an appropriate amount of phosphoric acid (8% of the mass of the corn straw), and stir and react in a magnetic stirrer at 35 °C for 4 h for a liquefaction reaction to form a uniform suspension.

[0046] 3. After the reaction is completed, filter the mixture and wash it to neutral to obtain the rice husk liquefied product.

[0047] 4. Using spray pyrolysis, set the feed pump pressure to 1.5 MPa, the nozzle aperture to 0.5 mm. Set the inlet temperature to 400 °C, the outlet temperature to 150 °C, and the carrier gas flow rate to 50 m 3 / h. Under the condition of nitrogen protection, the rice husk liquefied liquid is sprayed into the calcination furnace through a sprayer to form lightweight rice husk liquefied microspheres. The generated microspheres are collected and further dried in an oven at 105°C for 2 h to ensure complete removal of the residual solvent.

[0048] 5. The dried microspheres are placed in a tubular furnace and carbonized at 700°C for 2 h under nitrogen protection to obtain carbon aerogel microspheres.

[0049] Example 5

[0050] 1. Clean the rice husks and dry them to a constant weight, then crush them into fine powder with a particle size less than 0.5 mm.

[0051] 2. Mix the pretreated rice husk powder with a mixed solvent of ethanol and isopropanol (mixed at 1:1) at a mass ratio of 1:10. Add an appropriate amount of phosphoric acid (10% of the mass of the rice husks), and stir and react in a magnetic stirrer at 40°C for 4 h for the liquefaction reaction to form a uniform suspension.

[0052] 3. After the reaction is completed, filter the mixture and wash it to neutral to obtain the rice husk liquefied product.

[0053] 4. Using spray pyrolysis, set the feed pump pressure to 1.5 MPa, the nozzle aperture to 0.5 mm. The inlet temperature is set to 500°C, the outlet temperature is set to 150°C, and the carrier gas flow rate is 50 m 3 / h. Under the condition of argon protection, the rice husk liquefied liquid is sprayed into the calcination furnace through a sprayer to form lightweight rice husk liquefied microspheres. The generated microspheres are collected and further dried in an oven at 105°C for 2 h to ensure complete removal of the residual solvent.

[0054] 5. The dried microspheres are placed in a tubular furnace and carbonized at 750°C for 2 h under argon protection to obtain carbon aerogel microspheres.

[0055] Application Example

[0056] The above-prepared carbon aerogel microspheres are used as the electrode material of a supercapacitor, and the test results are shown in Table 1.

[0057] Table 1

[0058] Performance Index Example 1 Example 2 Example 3 Example 4 Example 5 Specific Capacitance (F / g) 117 150 210 220 228 Energy Density (Wh / kg) 10 13 14 15 18 Power Density (W / kg) 11500 12400 12400 12400 18500 <![CDATA[Density (g / cm 3 )]]> 0.25 0.2 0.2 0.2 0.1 <![CDATA[Specific surface area (m 2 / g)]]> 950 1200 1895 2400 2750 <![CDATA[Pore volume (cm 3 / g)]]> 1.5 1.8 1.8 1.8 2.6

[0059] The results show that the material exhibits excellent electrochemical performance, has a high specific capacitance and good cycle stability, and is suitable for the preparation of high-performance supercapacitors.

[0060] Figure 1It is the graph of the specific capacitance and specific surface area of the carbon aerogel electrode material in the embodiment. As can be seen from the graph, the change trend of the specific capacitance of the carbon aerogel electrode material is increasing with the increase of the specific surface area, and it has a high specific capacitance.

[0061] According to the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A preparation method of a biomass-based carbon aerogel, characterized in that, It includes the following steps: (1) After crushing the biomass raw material, add an organic solvent and mix evenly to obtain a biomass liquefied liquid; (2) Obtain biomass liquefied microspheres by spray pyrolysis of the liquefied liquid; (3) Dry the biomass liquefied microspheres and then carry out carbonization to obtain biomass-based carbon aerogel.

2. The preparation method according to claim 1, wherein, In step (1), an inorganic acid is also added. Specifically, after mixing the biomass powder and the solvent evenly, the inorganic acid is added and dissolved under acidic conditions.

3. The preparation method according to claim 2, characterized in that, The solvent includes at least one of phenol and p-cresol, and the inorganic acid includes at least one of sulfuric acid, hydrochloric acid, and nitric acid.

4. The preparation method according to claim 2, characterized in that, The mass ratio of the biomass raw material to the solvent is 1:(2 - 10), and the mass ratio of the biomass raw material to the inorganic acid is 10:(1 - 2).

5. The preparation method according to claim 1, characterized in that, In step (3), the carbonization is carried out under a protective atmosphere, the carbonization temperature is 650°C - 750°C, and the carbonization time is 2h - 3h.

6. The preparation method according to claim 1, wherein In step (2), the spray pyrolysis is to spray the biomass liquefied liquid into a calcination furnace through a sprayer to form lightweight rice husk liquefied microspheres.

7. The preparation method according to claim 6, characterized in that, The spray pressure is 0.1 - 1.5 MPa, the spray rate is 0.1 - 10 L / min, the inlet temperature is 200 - 600 °C, the outlet temperature is 100 - 200 °C, and the carrier gas flow rate is 10 - 100 m 3 / h.

8. The preparation method according to claim 1, characterized in that, The biomass raw material includes any one of rice husk, corn straw, and larch sawdust.

9. A biomass-based carbon aerogel, characterized in that, Prepared by the preparation method according to any one of claims 1 - 8.

10. Use of the biomass-based carbon aerogel according to claim 9 in electrochemical energy storage and pollutant adsorption.

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