CN115138334A - Nitrogen-doped biochar, preparation method thereof and application thereof in carbon dioxide adsorption - Google Patents
Nitrogen-doped biochar, preparation method thereof and application thereof in carbon dioxide adsorption Download PDFInfo
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Abstract
The invention provides nitrogen-doped biochar, a preparation method thereof and application thereof in carbon dioxide adsorption, and relates to the technical field of biochar materials. Mixing straw, biogas slurry and sodium sulfate to obtain a solid-liquid mixture; carrying out hydrothermal reaction on the solid-liquid mixture to obtain nitrogen-doped hydrothermal carbon; and mixing the nitrogen-doped hydrothermal carbon and potassium hydroxide, and activating in a nitrogen atmosphere to obtain the nitrogen-doped biochar. The biogas slurry is simultaneously used as a biomass nitrogen source and a liquid medium, and participates in the hydrothermal carbonization process to realize nitrogen doping of the biochar, so that the use of the traditional high-energy consumption chemical nitrogen source is reduced; the invention adopts sodium sulfate as an additive to effectively promote hydrothermal carbonization and improve nitrogen element doping efficiency, and is beneficial to subsequent activation and pore-forming. The invention can realize the green preparation of the nitrogen-doped biochar, ensures high doping efficiency and realizes the resource treatment of the straws and the biogas slurry, and the obtained nitrogen-doped biochar has good adsorption performance on carbon dioxide.
Description
Technical Field
The invention relates to the technical field of biochar materials, in particular to nitrogen-doped biochar, a preparation method thereof and application thereof in carbon dioxide adsorption.
Background
Hydrothermal treatment of biomass is a thermochemical reaction carried out under subcritical or supercritical water conditions, water providing the medium for a complex series of reactions. The biomass hydrothermal treatment can directly convert biomass raw materials with high carbon content and high moisture content without pre-drying, the process is an endothermic reaction, and generally the biomass raw materials are subjected to hydrolysis, depolymerization and condensation fractionation to finally form biochar, also called hydrothermal carbon.
Due to the good adsorption capacity and stable chemical property of the biochar, the biochar can finish the adsorption and recovery work of greenhouse gases under certain conditions, and further realize the trapping of the greenhouse gases. The biological carbon has the advantages of simple operation and good effect in practical application due to the strong adsorption capacity of the biological carbon, and the hydrothermal carbon has rich oxygen-containing functional groups and uniform carbon formation in carbon dioxide (CO) 2 ) The adsorption field has wide application prospect. The carbon dioxide is adsorbed by the biochar mainly by two adsorption modes, namely physical adsorption and chemical adsorption, wherein the main action source of the physical adsorption is intermolecular van der Waals force, the chemical adsorption relates to chemical reactions such as acid-base action, electron transfer and the like, and the chemical adsorption of the biochar on the carbon dioxide can be enhanced by doping nitrogen elements so as to improve the adsorption performance.
The alkalinity of the surface of the charcoal has an important effect on the adsorption of carbon dioxide, the alkaline surface functional group is the most main influencing factor, the nitrogen-containing functional group is the main source of the alkalinity of the surface of the charcoal, and the addition of nitrogen can change the acidity and alkalinity of the surface of the charcoal material, so that the hydrophilic property and the adsorption property of the surface of the charcoal material are improved. And nitrogen is one of the adjacent elements next to carbon in the periodic table, has chemical properties similar to carbon, and can form stable covalent bond with carbon and enable the stable existence of the carbon in the carbon skeleton; the size of nitrogen atoms is similar to that of carbon, so that the length of a C-N bond is very close to that of a C-C bond, the deformation of a carbon network structure after doping can be effectively minimized, and the geometric structure of the carbon network is kept to a great extent, so that the nitrogen-doped carbon has the characteristics of richness, easiness in synthesis and excellent performance. The nitrogen sources adopted for preparing the nitrogen-doped biochar at the present stage are high-energy-consumption chemical products such as urea, melamine and the like, and the green production is difficult to realize effectively.
In addition, the biogas slurry obtained after the anaerobic fermentation of the biomass at the present stage still has a certain treatment problem, and the environmental pollution is easily caused by improper treatment.
Disclosure of Invention
In view of the above, the present invention aims to provide a nitrogen-doped biochar, a preparation method thereof, and an application thereof in carbon dioxide adsorption. The preparation method provided by the invention takes biogas slurry as a nitrogen source, realizes the green preparation of nitrogen-doped biochar, and realizes the recycling treatment of the biogas slurry.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of nitrogen-doped biochar, which comprises the following steps:
mixing the straws, the biogas slurry and sodium sulfate to obtain a solid-liquid mixture;
carrying out hydrothermal reaction on the solid-liquid mixture to obtain nitrogen-doped hydrothermal carbon;
and mixing the nitrogen-doped hydrothermal carbon with potassium hydroxide, and activating in a nitrogen atmosphere to obtain the nitrogen-doped biochar.
Preferably, the straws comprise one or more of corn straws, cotton straws and wheat straws, and the particle size of the straws is less than 0.3 mm.
Preferably, the total nitrogen content of the biogas slurry is 2.5 to 4g/L.
Preferably, the mass of the straw is 15 to 20 percent of the sum of the mass of the straw and the mass of the biogas slurry; the mass of the sodium sulfate is 0.5 to 1.5 percent of the sum of the mass of the straws and the mass of the biogas slurry.
Preferably, the temperature of the hydrothermal reaction is 200 to 280 ℃ and the time is 1 to 3h.
Preferably, the mass ratio of the nitrogen-doped hydrothermal carbon to the potassium hydroxide is 1 to 1.
Preferably, the activation temperature is 650 to 800 ℃, and the activation time is 1 to 3h; the heating rate from the room temperature to the activation temperature is 5 to 10 ℃/min.
The invention provides the nitrogen-doped biochar prepared by the preparation method in the technical scheme.
Preferably, the total specific surface area of the nitrogen-doped biochar is 1600 to 1900m 2 The nitrogen content is 4 to 6wt percent per gram.
The invention provides application of the nitrogen-doped biochar in the technical scheme in carbon dioxide adsorption.
The invention provides a preparation method of nitrogen-doped biochar, which comprises the following steps: mixing the straws, the biogas slurry and sodium sulfate to obtain a solid-liquid mixture; carrying out hydrothermal reaction on the solid-liquid mixture to obtain nitrogen-doped hydrothermal carbon; and mixing the nitrogen-doped hydrothermal carbon with potassium hydroxide, and activating in a nitrogen atmosphere to obtain the nitrogen-doped biochar. The biogas slurry is used as a nitrogen source and a liquid medium for hydrothermal reaction at the same time, and participates in the hydrothermal carbonization process to realize nitrogen doping of the biochar, and the biogas slurry is used as a biomass nitrogen source, so that the use of the traditional high-energy-consumption chemical nitrogen source is reduced; the biomass nitrogen source has a complex form of nitrogen element, the doping efficiency is lower than that of the traditional nitrogen source, the sodium sulfate is used as an additive to participate in hydrothermal reaction, the hydrothermal carbonization efficiency can be promoted, the densification degree of the product carbon is improved, the doping efficiency of the nitrogen element is improved, the addition of the sodium sulfate is beneficial to subsequent activated pore-forming, and therefore the carbon dioxide adsorption performance of the biochar is improved to a certain extent. The preparation method provided by the invention can realize the green preparation of the nitrogen-doped biochar, ensures high doping efficiency and realizes the resource treatment of the straws and the biogas slurry.
The invention provides the nitrogen-doped biochar prepared by the preparation method in the technical scheme. The total specific surface area of the nitrogen-doped biochar provided by the invention is 1600-1900 m 2 (iv)/g, the nitrogen content is 4 to 6wt%,the nitrogen content is high, and the carbon dioxide adsorption performance is good. The results of examples show that the adsorption capacity of the nitrogen-doped biochar prepared by the invention on carbon dioxide is 5.60 to 6.40mmol/g (0 ℃,100 kPa) and 4.10 to 4.50mmol/g (25 ℃,100 kPa).
Drawings
FIG. 1 is a schematic flow diagram of the process for preparing nitrogen-doped biochar according to the present invention;
FIG. 2 scanning electron micrograph of nitrogen-doped biochar prepared in example 1.
Detailed Description
The invention provides a preparation method of nitrogen-doped biochar, which comprises the following steps:
mixing the straws, the biogas slurry and sodium sulfate to obtain a solid-liquid mixture;
carrying out hydrothermal reaction on the solid-liquid mixture to obtain nitrogen-doped hydrothermal carbon;
and mixing the nitrogen-doped hydrothermal carbon with potassium hydroxide, and activating in a nitrogen atmosphere to obtain the nitrogen-doped biochar.
FIG. 1 is a schematic flow chart of the present invention for preparing nitrogen-doped biochar. The present invention will be described in detail with reference to fig. 1.
The invention mixes the straw, the biogas slurry and the sodium sulfate to obtain a solid-liquid mixture. In the invention, the straw preferably comprises one or more of corn straw, cotton straw and wheat straw, and more preferably is corn straw; the invention has no special requirements on the source of the straws, and the straws with the sources well known by the technicians in the field can be adopted. In the invention, the grain diameter of the straw is preferably less than 0.3mm, and the grain diameter of the straw is preferably controlled to be less than 0.3mm by crushing. The invention selects the biomass raw material of the straws as the raw material for preparing the biochar, is beneficial to forming a good carbon structure by hydrothermal reaction and promotes the carbon formation. In the invention, the total nitrogen content of the biogas slurry is preferably 2.5 to 4g/L; the source of the biogas slurry is not particularly required, and the biogas slurry from which the source is known by a person skilled in the art can be adopted. A large amount of nitrogen exists in the biogas slurry, and the nitrogen mainly exists in two forms of ammonia nitrogen and nitrate nitrogen, wherein the ammonia nitrogenIs a main component with high proportion, which causes a large amount of NH in the biogas slurry 4 + And NH 3 The invention takes biogas slurry to replace water as a reaction medium of hydrothermal reaction and provides a biomass nitrogen source (NH) for preparing nitrogen-doped biochar 4 + Is a main nitrogen source), and reduces the use of the traditional high-energy consumption chemical nitrogen source. The biomass nitrogen source has a complex form of nitrogen element, and the doping efficiency is lower than that of the traditional nitrogen sources such as urea, melamine and the like. In the invention, the mass of the straw is preferably 15 to 20 percent of the sum of the mass of the straw and the mass of the biogas slurry, and more preferably 15 percent; the sodium sulfate is crystal powder, and the mass of the sodium sulfate is preferably 0.5-1.5%, more preferably 0.8-1.3%, and even more preferably 1.2% of the sum of the mass of the straws and the mass of the biogas slurry. The method for mixing the straws, the biogas slurry and the sodium sulfate has no special requirements, the straws and the biogas slurry are fully mixed, and the straws and the biogas slurry are preferably mixed firstly, and then the sodium sulfate is added into the straws and the biogas slurry for mixing.
After a solid-liquid mixture is obtained, the solid-liquid mixture is subjected to hydrothermal reaction to obtain the nitrogen-doped hydrothermal carbon. In the present invention, the hydrothermal reaction is performed in a hydrothermal reaction vessel, and in the present invention, it is preferable that the hydrothermal reaction is performed after air in the hydrothermal reaction vessel is purged with nitrogen gas. In the invention, the temperature of the hydrothermal reaction is preferably 200 to 280 ℃, more preferably 220 to 240 ℃, and the time is preferably 1 to 3 hours, more preferably 2 hours; the hydrothermal reaction is preferably carried out under stirring, preferably at a rate of 80rpm. In the hydrothermal reaction process, the straws are firstly hydrolyzed and depolymerized, then condensed and fractionated, and finally polymerized into carbon, nitrogen elements in the biogas slurry can be replaced with carbon in a carbon skeleton, so that doping is carried out, and the nitrogen elements can gradually penetrate into the carbon skeleton to form more stable nitrogen-containing functional groups along with the reaction; the sodium sulfate is used as an additive to effectively promote hydrothermal carbon formation and improve the doping efficiency of nitrogen elements. After the hydrothermal reaction is finished, the obtained product is preferably filtered, and the solid phase obtained by filtering is sequentially subjected to alcohol washing, water washing and drying to obtain the nitrogen-doped hydrothermal carbon. In the invention, the alcohol reagent adopted by the alcohol washing is preferably ethanol with 95% volume fraction, and the water adopted by the water washing is preferably deionized water; the temperature of the drying is preferably 105 ℃ and the time is 12h, and the drying is preferably carried out in an oven.
After the nitrogen-doped hydrothermal carbon is obtained, the nitrogen-doped hydrothermal carbon and potassium hydroxide are mixed and activated in a nitrogen atmosphere to obtain the nitrogen-doped biological carbon. In the present invention, the potassium hydroxide is preferably potassium hydroxide powder; the mass ratio of the nitrogen-doped hydrothermal carbon to the potassium hydroxide is preferably 1 to 1, more preferably 1:1; the method for mixing the nitrogen-doped hydrothermal carbon and the potassium hydroxide has no special requirement, and the uniform mixing is ensured. In the invention, the activation temperature is preferably 650 to 800 ℃, more preferably 800 ℃, and the activation time is preferably 1 to 3 hours, more preferably 2 hours; the rate of temperature increase from room temperature to the activation temperature is preferably 5 to 10 ℃/min, more preferably 5 ℃/min. In the present invention, the specific operation of the activation is preferably: placing the mixture obtained by mixing the nitrogen-doped hydrothermal carbon and the potassium hydroxide into a tubular furnace, and purging the tubular furnace by using nitrogen to realize a nitrogen atmosphere; and then heating the tube furnace from room temperature to 650 to 800 ℃, and activating at the temperature. In the activation process, the potassium hydroxide is converted into a molten state to etch the surface of the biochar, so that the activation pore-forming is realized; and simultaneously, the sodium sulfate also promotes the activation and pore-forming. After the activation, preferably, the obtained product is cooled to room temperature and then sequentially subjected to acid washing, water washing and drying to obtain nitrogen-doped biochar; the cooling is preferably furnace cooling (in a nitrogen atmosphere); the acid reagent for acid washing is preferably diluted hydrochloric acid, and the concentration of the diluted hydrochloric acid is preferably 0.05mol/L; the washing water is preferably deionized water; the temperature of the drying is preferably 105 ℃ and the time is preferably 12h, and the drying is preferably carried out in an oven.
The method takes the straws as the raw material, takes the biogas slurry as the nitrogen source and the hydrothermal reaction medium, prepares the nitrogen-doped biochar through hydrothermal reaction and activation modification, and provides technical support for green production of the nitrogen-doped biochar and solving the problem of biogas slurry treatment.
The invention provides the nitrogen-doped biochar prepared by the preparation method in the technical scheme. The total specific surface area of the nitrogen-doped charcoal provided by the invention is 1600 to 1900m 2 The nitrogen content is 4 to 6wt%, the nitrogen content is high, and the carbon dioxide adsorption material has good adsorption performance on carbon dioxide and good application prospect in the field of carbon dioxide adsorption.
The nitrogen-doped biochar provided by the invention, the preparation method thereof and the application thereof in carbon dioxide adsorption are described in detail below with reference to the examples, but the invention is not to be construed as being limited by the scope of the invention.
Example 1
The preparation method of the nitrogen-doped biochar comprises the following steps:
uniformly mixing corn straw powder (with the particle size of less than 0.3mm and the mass of 9 g), sodium sulfate (with the mass of 0.7 g) and biogas slurry (51 g and the total nitrogen content of 2.5 g/L), adding the mixture into a hydrothermal reaction kettle, introducing nitrogen to completely exhaust air in the reaction kettle, and then carrying out hydrothermal reaction at the temperature of 240 ℃, the reaction time of 2 hours and the stirring rate of 80rpm; and filtering the obtained hydrothermal reaction product, washing the solid phase obtained by filtering with ethanol and deionized water with the volume fraction of 95%, and drying in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped hydrothermal carbon.
Mixing the nitrogen-doped hydrothermal carbon and potassium hydroxide powder, placing the mixture in a tubular furnace for activation, wherein the mass ratio of the nitrogen-doped biological carbon to the potassium hydroxide powder is 1:1, purging the tubular furnace by using nitrogen before activation, the activation temperature of the tubular furnace is 800 ℃, the activation time is 2 hours, the heating rate is set to be 5 ℃/min in the activation process, and the activation and heating processes are carried out in the nitrogen atmosphere; and cooling the activated biochar to room temperature under nitrogen airflow, repeatedly washing the biochar to be neutral by using dilute hydrochloric acid (the concentration is 0.05 mol/L) and deionized water, carrying out suction filtration on the washed biochar, and drying the biochar in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped biochar.
FIG. 2 is a scanning electron micrograph of the nitrogen-doped biochar prepared in example 1. As can be seen from FIG. 2, the prepared nitrogen-doped biochar material has a good pore structure.
The nitrogen content (namely the nitrogen doping amount) of the nitrogen-doped biochar prepared in the example 1 is 4.57 wt%, the hydrogen-carbon ratio is 0.066, and the total specific surface area is 1860m 2 Per g, specific micropore surface area of 1540m 2 The ratio of micropores was 82.8%, and the adsorption capacities for carbon dioxide were 5.60mmol/g (0 ℃ C., 100 kPa) and 4.30mmol/g (25 ℃ C., 100 kPa). The prepared nitrogen-doped biochar is used for carbon dioxide adsorption, and the adsorption performance of the nitrogen-doped biochar is superior to that of common commercial activated carbon (3.0 to 3.5mmol/g,0 ℃ and 100 kPa).
Example 2
The preparation method of the nitrogen-doped biochar comprises the following steps:
uniformly mixing corn straw powder (the particle size is less than 0.3mm and the mass is 9 g), sodium sulfate (crystal powder and the mass is 0.7 g) and biogas slurry (51 g and the total nitrogen content is 3.0 g/L), adding the mixture into a hydrothermal reaction kettle, introducing nitrogen to completely exhaust air in the reaction kettle, and then carrying out hydrothermal reaction at the temperature of 220 ℃, the reaction time of 2 hours and the stirring speed of 80rpm; and filtering the obtained hydrothermal reaction product, washing a solid phase substance obtained by filtering with ethanol with the volume fraction of 95% and deionized water, and placing the solid phase substance in an oven for drying at the temperature of 105 ℃ for 12h to obtain the nitrogen-doped hydrothermal carbon.
Mixing the nitrogen-doped hydrothermal carbon and potassium hydroxide powder, placing the mixture in a tubular furnace for activation, wherein the mass ratio of the nitrogen-doped biological carbon to the potassium hydroxide powder is 1:1, purging the tubular furnace by using nitrogen before activation, the activation temperature of the tubular furnace is 800 ℃, the activation time is 2 hours, the heating rate in the activation process is set to be 5 ℃/min, and the activation and heating processes are carried out in a nitrogen atmosphere; and cooling the activated biochar to room temperature under nitrogen airflow, repeatedly washing the biochar to be neutral by using dilute hydrochloric acid (the concentration is 0.05 mol/L) and deionized water, carrying out suction filtration on the washed biochar, and drying the biochar in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped biochar.
Example 2 preparation of the resulting Nitrogen-doped organismsThe nitrogen content of the carbon is 5.69 wt percent, the hydrogen-carbon ratio is 0.065, and the total specific surface area is 1770m 2 (ii)/g, specific micropore surface area of 1430m 2 A micropore occupying ratio of 80.8%, and an adsorption capacity for carbon dioxide of 6.40mmol/g (0 ℃ C., 100 kPa) and 4.50mmol/g (25 ℃ C., 100 kPa). The prepared nitrogen-doped biochar is used for carbon dioxide adsorption, and the adsorption performance of the nitrogen-doped biochar is superior to that of common commercial activated carbon (3.0 to 3.5mmol/g,0 ℃ and 100 kPa).
Example 3
The preparation method of the nitrogen-doped biochar comprises the following steps:
uniformly mixing corn straw powder (the particle size is less than 0.3mm and the mass is 12 g), sodium sulfate (crystal powder and the mass is 0.5 g) and biogas slurry (48 g and the total nitrogen content is 3.0 g/L), adding the mixture into a hydrothermal reaction kettle, introducing nitrogen to completely exhaust air in the reaction kettle, and then carrying out hydrothermal reaction at the temperature of 240 ℃, the reaction time of 3 hours and the stirring speed of 80rpm; and filtering the obtained hydrothermal reaction product, washing the solid phase obtained by filtering with ethanol and deionized water with the volume fraction of 95%, and drying in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped hydrothermal carbon.
Mixing the nitrogen-doped hydrothermal carbon and potassium hydroxide powder, placing the mixture in a tubular furnace for activation, wherein the mass ratio of the nitrogen-doped biological carbon to the potassium hydroxide powder is 1:1, purging the tubular furnace by using nitrogen before activation, the activation temperature of the tubular furnace is 800 ℃, the activation time is 2 hours, the heating rate in the activation process is set to be 5 ℃/min, and the activation and heating processes are carried out in a nitrogen atmosphere; and cooling the activated biochar to room temperature under nitrogen airflow, repeatedly washing the biochar to be neutral by using dilute hydrochloric acid (the concentration is 0.05 mol/L) and deionized water, carrying out suction filtration on the washed biochar, and drying the biochar in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped biochar.
The nitrogen content of the nitrogen-doped biochar prepared in example 3 is 5.07 wt%, the hydrogen-carbon ratio is 0.067, and the total specific surface area is 1690m 2 Per g, specific surface area of micropores 1360m 2 A micropore content of 80.5%, an adsorption capacity for carbon dioxide of 6.00mmol/g (0 ℃ C., 100 kPa) and 4.10mmol/g (25 ℃ C., 10 kPa)0 kPa). The prepared nitrogen-doped biochar is used for carbon dioxide adsorption, and the adsorption performance of the nitrogen-doped biochar is superior to that of common commercial activated carbon (3.0 to 3.5mmol/g,0 ℃ and 100 kPa).
Comparative example 1
The preparation method of the nitrogen-doped biochar comprises the following steps:
uniformly mixing corn straw powder (the particle size is less than 0.3mm, the mass is 9 g) and biogas slurry (51 g, the total nitrogen content is 2.5 g/L), adding the mixture into a hydrothermal reaction kettle, introducing nitrogen to completely exhaust air in the reaction kettle, and then carrying out hydrothermal reaction at the temperature of 240 ℃, the reaction time of 2 hours and the stirring speed of 80rpm; filtering the obtained hydrothermal reaction product, washing a solid phase substance obtained by filtering with ethanol with the volume fraction of 95% and deionized water, and placing the solid phase substance in an oven for drying at the temperature of 105 ℃ for 12h to obtain nitrogen-doped hydrothermal carbon;
mixing the nitrogen-doped hydrothermal carbon and potassium hydroxide powder, placing the mixture in a tubular furnace for activation, wherein the mass ratio of the nitrogen-doped biological carbon to the potassium hydroxide powder is 1:1, purging the tubular furnace by using nitrogen before activation, the activation temperature of the tubular furnace is 800 ℃, the activation time is 2 hours, the heating rate is set to be 5 ℃/min in the activation process, and the activation and heating processes are carried out in the nitrogen atmosphere; and cooling the activated biochar to room temperature under nitrogen airflow, repeatedly washing the biochar to be neutral by using dilute hydrochloric acid (the concentration is 0.05 mol/L) and deionized water, carrying out suction filtration on the washed biochar, and drying the biochar in an oven at the temperature of 105 ℃ for 12 hours to obtain the nitrogen-doped biochar.
The nitrogen-doped biochar prepared in comparative example 1 had a nitrogen content of 1.87wt%, a hydrogen-to-carbon ratio of 0.081, and a total specific surface area of 1840m 2 (g) a specific surface area of 1230m pores 2 A micropore occupying ratio of 66.8% to 4.30mmol/g (0 ℃ C., 100 kPa) and an adsorption capacity for carbon dioxide of 3.20mmol/g (25 ℃ C., 100 kPa).
Compared with the embodiment 1, the addition of sodium sulfate is omitted in the comparative example 1, the nitrogen doping effect and the carbon forming effect of the prepared nitrogen-doped biochar are obviously reduced, and the adsorption performance of the biochar on carbon dioxide is also obviously reduced.
According to the embodiment, the preparation method provided by the invention can realize the green preparation of the nitrogen-doped biochar, ensures high doping efficiency, realizes the resource treatment of the straw and the biogas slurry, and has good adsorption performance on carbon dioxide.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. The preparation method of the nitrogen-doped biochar is characterized by comprising the following steps of:
mixing the straws, the biogas slurry and sodium sulfate to obtain a solid-liquid mixture;
carrying out hydrothermal reaction on the solid-liquid mixture to obtain nitrogen-doped hydrothermal carbon;
and mixing the nitrogen-doped hydrothermal carbon with potassium hydroxide, and activating in a nitrogen atmosphere to obtain the nitrogen-doped biochar.
2. The preparation method of claim 1, wherein the straw comprises one or more of corn straw, cotton straw and wheat straw, and the particle size of the straw is less than 0.3 mm.
3. The preparation method of claim 1, wherein the total nitrogen content of the biogas slurry is 2.5-4 g/L.
4. The method of claim 1~3 wherein the mass of straw is 15 to 20% of the sum of the mass of straw and biogas slurry; the mass of the sodium sulfate is 0.5 to 1.5 percent of the sum of the mass of the straws and the biogas slurry.
5. The preparation method according to claim 1, wherein the hydrothermal reaction is carried out at a temperature of 200 to 280 ℃ for 1 to 3 hours.
6. The preparation method according to claim 1, wherein the mass ratio of the nitrogen-doped hydrothermal carbon to the potassium hydroxide is 1 to 1.
7. The preparation method according to claim 1, wherein the activation temperature is 650 to 800 ℃ and the activation time is 1 to 3h; the heating rate from the room temperature to the activation temperature is 5 to 10 ℃/min.
8. The nitrogen-doped biochar prepared by the preparation method of any one of claims 1~7.
9. The nitrogen-doped biochar as claimed in claim 8, wherein the total specific surface area of the nitrogen-doped biochar is 1600 to 1900m 2 The nitrogen content is 4 to 6wt percent per gram.
10. Use of the nitrogen-doped biochar of claim 8 or 9 for carbon dioxide adsorption.
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| CN115445574A (en) * | 2022-10-11 | 2022-12-09 | 中国科学院东北地理与农业生态研究所 | Preparation method of N, S co-doped hydrothermal carbon and application thereof in removing Cr (VI) in water |
| CN115722194A (en) * | 2022-12-07 | 2023-03-03 | 江汉大学 | Nitric acid modified lotus leaf carbon adsorption material and preparation method and application thereof |
| CN117101675A (en) * | 2023-10-17 | 2023-11-24 | 中国农业科学院农业环境与可持续发展研究所 | High-entropy alloy modified nitrogen-doped biochar as well as preparation method and application thereof |
| CN117383539A (en) * | 2023-10-30 | 2024-01-12 | 北京市科学技术研究院城市安全与环境科学研究所 | Preparation of modified straw-based hydrothermal carbon and application of modified straw-based hydrothermal carbon in carbon dioxide fixation |
| CN117623302A (en) * | 2023-12-01 | 2024-03-01 | 浙江大学 | Preparation method and application of heteroatom doped biochar |
| CN117383539B (en) * | 2023-10-30 | 2024-05-10 | 北京市科学技术研究院城市安全与环境科学研究所 | Preparation of modified straw-based hydrothermal carbon and application of modified straw-based hydrothermal carbon in carbon dioxide fixation |
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| CN117101675A (en) * | 2023-10-17 | 2023-11-24 | 中国农业科学院农业环境与可持续发展研究所 | High-entropy alloy modified nitrogen-doped biochar as well as preparation method and application thereof |
| CN117101675B (en) * | 2023-10-17 | 2024-02-09 | 中国农业科学院农业环境与可持续发展研究所 | High-entropy alloy modified nitrogen-doped biochar as well as preparation method and application thereof |
| CN117383539A (en) * | 2023-10-30 | 2024-01-12 | 北京市科学技术研究院城市安全与环境科学研究所 | Preparation of modified straw-based hydrothermal carbon and application of modified straw-based hydrothermal carbon in carbon dioxide fixation |
| CN117383539B (en) * | 2023-10-30 | 2024-05-10 | 北京市科学技术研究院城市安全与环境科学研究所 | Preparation of modified straw-based hydrothermal carbon and application of modified straw-based hydrothermal carbon in carbon dioxide fixation |
| CN117623302A (en) * | 2023-12-01 | 2024-03-01 | 浙江大学 | Preparation method and application of heteroatom doped biochar |
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