Heteroatom-doped porous carbon material for carbon dioxide adsorption as well as preparation method and application of heteroatom-doped porous carbon material

Abstract

The invention provides a heteroatom-doped porous carbon material for carbon dioxide adsorption as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, drying and crushing waste biomass to obtain raw material powder; s2, mixing the raw material powder with an activating agent, and fully grinding to obtain a mixture of the raw material powder and the activating agent powder; s3, dissolving one or more heteroatom sources in hot deionized water to obtain a hot solution, pouring the mixture of the raw materials and the activator powder in the step S2 into the hot solution, and heating and stirring until water is evaporated; s4, performing high-temperature carbonization on the mixture finally obtained in the step S3 in an anoxic environment; and S5, cleaning and drying the product in the step S4 to obtain the heteroatom-doped porous carbon material. The heteroatom-doped porous carbon material disclosed by the invention has a highly developed pore structure, and the porous carbon prepared by taking the waste biomass as a precursor is used as a carbon dioxide adsorbent, so that high-value utilization of waste biomass resources is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection adsorption materials, and particularly relates to a heteroatom-doped porous carbon material for carbon dioxide adsorption, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of human industry and the continuous consumption of fossil energy, a large amount of greenhouse gases (such as carbon dioxide, etc.) are emitted into the atmosphere, causing global climate change problems. Porous carbon materials are a kind of materials with excellent adsorption properties. The porous carbon materials prepared from biomass as a precursor have characteristics such as high mechanical strength and highly developed pores, and have very high research value in the field of carbon dioxide adsorption. Moreover, biomass is rich in sources, simple to prepare, and low in cost. Using it as a raw material can also improve the utilization rate of waste biomass and achieve the effect of energy conservation and environmental protection.

[0003] A large number of studies have shown that porous carbon materials, as a kind of green and environmental protection adsorbent and catalyst, have controllable structural properties. The addition of heteroatoms can change the pore structure and specific surface area inside the porous carbon material, and the number of functional groups on its surface will also change accordingly. On the other hand, it will also improve the hydrophilicity of the carbon material surface. By doping different heteroatoms, the characteristics of biomass-derived porous carbon materials can be changed in many aspects.

[0004] However, the commonly used method in the prior art is the direct solid-phase mixing of biomass and heteroatom sources, which will lead to low doping efficiency and even uneven doping. Summary of the Invention

[0005] Aiming at the above technical problems, the present invention provides a heteroatom-doped porous carbon material for carbon dioxide adsorption and a preparation method thereof. This method is based on the effective doping of nitrogen and sulfur to prepare waste biomass-derived porous carbon materials. The prepared heteroatom-doped porous carbon materials have a highly developed pore structure and exhibit excellent carbon dioxide adsorption capacity.

[0006] The present invention also provides an application of a heteroatom-doped porous carbon material for carbon dioxide adsorption as a carbon dioxide adsorbent, and the carbon dioxide adsorption effect is remarkable.

[0007] In the present invention, nitrogen (N) is one of the heteroatoms in the carbon material and can be introduced into the carbon skeleton in different configurations such as pyrrole nitrogen, pyridine nitrogen, and quaternary ammonium nitrogen, increasing the chemical active sites and structural defects of the carbon material, thereby improving the surface adsorption capacity of carbon. Sulfur (S), as a chemical element with high capacity, has a large electronegativity and is easy to form chemical bonds with the adsorbed gas, promoting the uneven distribution of the electron cloud on the surface of the porous carbon and the generation of defect sites. Among them, the S=O bond can enhance the adsorption capacity of CO2. The present invention optimizes the technical aspects of the heteroatom doping method and obtains porous carbon with more excellent CO2 adsorption performance.

[0008] Among numerous waste biomasses, fruit peels are the most common, especially those of citrus fruits. Their peels are mostly inedible for humans and are often directly discarded, generating basically no economic benefits. In terms of composition and structure, for example, pomelo peel has a natural sponge-like foam structure, containing approximately 78% hemicellulose, 7%-21% pectin, and free sugars. At high temperatures, highly cross-linked amorphous hemicellulose can form non-graphitized hard carbon materials. Meanwhile, through modification methods such as activation and heteroatom doping, an adsorbent material with excellent carbon dioxide adsorption performance, environmental friendliness, and low cost can be formed. The present invention relates to a preparation method of a doped porous carbon material using waste biomasses such as fruit shells or peels and its application as a carbon dioxide adsorbent, highly valorizing waste biomass resources, having a rich pore structure and a large specific surface area, and having high environmental protection application value.

[0009] Note that the recitation of these objectives does not preclude the existence of other objectives. One embodiment of the present invention does not need to achieve all of the above objectives. Objectives other than the above can be extracted from the descriptions in the specification, drawings, and claims.

[0010] The present invention achieves the above technical objectives through the following technical means.

[0011] A preparation method of a heteroatom-doped porous carbon material for carbon dioxide adsorption, comprising the following steps:

[0012] Step S1, drying and pulverizing the waste biomass: drying and pulverizing the waste biomass to obtain raw material powder;

[0013] Step S2, mixing the waste biomass with an activator: mixing the raw material powder in Step S1 with the activator and thoroughly grinding to obtain a mixture of the raw material and the activator powder;

[0014] Step S3, effectively introducing the heteroatom source: dissolving one or more heteroatom sources in hot deionized water to obtain a hot solution, and pouring the mixture of the raw material and the activator powder in Step S2 into the hot solution, heating and stirring until the water evaporates;

[0015] Step S4, high-temperature carbonization: performing high-temperature carbonization on the mixture obtained in the last step of Step S3 in an anoxic environment;

[0016] Step S5, cleaning and drying the doped porous carbon material: cleaning and drying the product of Step S4 to obtain a heteroatom-doped porous carbon material for carbon dioxide adsorption.

[0017] In the above solution, the waste biomass in Step S1 includes fruit shells or peels.

[0018] Further, the waste biomass includes one or a combination of more than one of pomelo peel, orange peel, tangerine peel, sugarcane peel or coconut shell.

[0019] In the above solution, the activator in step S2 includes one or a combination of two of potassium hydroxide, zinc chloride, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium oxalate, sodium oxalate;

[0020] The raw material powder and the activator are mixed at a weight ratio of 1:0.5 to 1:1.5.

[0021] In the above solution, in step S2, the raw material powder in step S1 is mixed and placed in a mortar for sufficient grinding.

[0022] In the above solution, the heteroatom source in step S3 includes one or a combination of two of sulfur-containing chemical reagents, nitrogen-containing chemical reagents, phosphorus-containing chemical reagents;

[0023] The sulfur-containing chemical reagent includes one or a combination of two of sodium sulfide, potassium sulfide; the nitrogen-containing chemical reagent includes one or a combination of two of melamine, urea, ammonium carbonate, ammonium bicarbonate, ammonium sulfate, imidazole compounds;

[0024] The phosphorus-containing chemical reagent includes one or a combination of two of phosphoric acid, phosphorous acid, ammonium dihydrogen phosphate, hypophosphorous acid;

[0025] The mass of the heteroatom source is 20% - 80% of the raw material powder.

[0026] In the above solution, the temperature of heating and stirring in step S3 is 60 - 120 °C, and the heating and stirring time is 2 - 12 h.

[0027] In the above solution, the anoxic environment in step S4 refers to carbonization under an inert gas atmosphere. Preferably, the inert gas includes argon, nitrogen and their mixture; the inert gas purge rate is 50 - 200 mL / min; the high temperature refers to a temperature of 700 - 1000 °C; the heating rate is 5 °C / min, and the holding time is 1 - 5 h.

[0028] In the above solution, the cleaning in step S5 includes soaking in an acidic solution, then filtering by suction and washing the product with deionized water until the filtrate is neutral, and finally drying;

[0029] The acidic solution is an HCl or H2SO4 solution with a diluted concentration of 2 mol / L;

[0030] The drying temperature is 100 - 200 °C, and the drying duration is 24 hours.

[0031] A heteroatom-doped porous carbon material for carbon dioxide adsorption, which is prepared according to the preparation method of the heteroatom-doped porous carbon material for carbon dioxide adsorption.

[0032] An application of the heteroatom-doped porous carbon material for carbon dioxide adsorption in a carbon dioxide adsorbent.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The beneficial effects of the present invention are remarkable. First, activation is carried out under normal pressure conditions, avoiding the complexity and safety hazards brought by the high-pressure environment, making the whole process safer and more operable. Secondly, the present invention only needs to carry out a single high-temperature carbonization process, thus simplifying the cumbersome steps of multiple carbonizations in the traditional method. This innovative step not only improves production efficiency, shortens the reaction time, but also effectively reduces production costs. The heteroatom-doped porous carbon material prepared by this method has a highly developed pore structure, making it excellent in the adsorption capacity of carbon dioxide. The excellent performance of this material makes it have broad application prospects in the fields of environmental protection and gas separation. In addition, due to the lower energy consumption required by this method, compared with other activation methods, the present invention also shows obvious advantages in resource utilization and environmental friendliness.

[0035] The present invention uses the discarded biomass fruit shell or peel as a precursor to prepare porous carbon as a carbon dioxide adsorbent. The fruit shell or peel that should have been discarded is prepared into a porous carbon adsorbent with high value effects. It has a highly developed pore structure and exhibits excellent carbon dioxide adsorption capacity. In particular, the nitrogen-doped porous carbon has a CO2 adsorption capacity of up to 4.7 mmol / g at 25 °C and one atmosphere. This excellent gas adsorption performance makes it have broad application potential in many industrial fields. In the carbon capture and storage (CCS) technology, this material can be used to reduce the carbon dioxide emitted by industries, which is beneficial to helping enterprises achieve a lower carbon footprint and meet the global emission reduction goals. In addition, in the process of gas separation and purification, an efficient carbon dioxide adsorbent can improve the separation efficiency and reduce energy consumption, especially showing excellent performance in natural gas treatment and biogas purification. The present invention realizes the effective utilization of discarded biomass to a certain extent, gives full play to the recycling value of resources, and promotes the development of circular economy. By converting discarded biomass into high-performance adsorption materials, it not only contributes to environmental protection, but also provides new ideas for the sustainable development of related industries, having important practical significance and economic value.

[0036] Note that the recording of these effects does not prevent the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. Effects other than the above can be obviously seen and extracted from the descriptions in the specification, drawings, claims, etc. Brief Description of the Drawings

[0037] Figure 1 are the microscopic morphology structure diagrams of the biomass raw materials used in Examples 1, 2, and 3 of the present invention.

[0038] Figure 2 is the microscopic morphology structure diagram of the nitrogen-doped porous carbon material of Example 1 of the present invention.

[0039] Figure 3 is the carbon dioxide adsorption-desorption isotherm of Example 1 of the present invention.

[0040] Figure 4 is the X-ray powder diffraction pattern of Example 1 of the present invention.

[0041] Figure 5 is the Raman spectrum of Example 1 of the present invention.

[0042] Figure 6 is the microscopic morphology structure diagram of the sulfur-doped porous carbon material of Example 2 of the present invention.

[0043] Figure 7 is the carbon dioxide adsorption-desorption isotherm of Example 2 of the present invention.

[0044] Figure 8 is the X-ray powder diffraction pattern of Example 2 of the present invention.

[0045] Figure 9 is the Raman spectrum of Example 2 of the present invention.

[0046] Figure 10 is the microscopic morphology structure diagram of the nitrogen-sulfur co-doped porous carbon material of Example 3 of the present invention.

[0047] Figure 11 is the carbon dioxide adsorption-desorption isotherm of Example 3 of the present invention.

[0048] Figure 12 is the X-ray powder diffraction pattern of Example 3 of the present invention.

[0049] Figure 13 is the Fourier transform infrared spectrum of Example 3 of the present invention.

[0050] Figure 14 is the Raman spectrum of Example 3 of the present invention. Detailed Description of the Invention

[0051] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of specific embodiments of the present invention with reference to the accompanying drawings. Without conflict, the features in the embodiments of the present invention can be combined with each other. In addition, in the preparation processes of the following embodiments, unless otherwise specified, they are all conventional means in the prior art in this field, and thus will not be elaborated in detail; the raw materials used in the following embodiments are all commercially available products.

[0052] Example 1: Preparation of nitrogen-doped porous carbon material

[0053] A preparation method of a heteroatom-doped porous carbon material for carbon dioxide adsorption includes the following steps:

[0054] Step S1: Dry and crush pomelo peel to obtain raw material powder;

[0055] Step S2: Mix waste biomass with activator: Mix 4 g of the raw material pomelo peel powder in Step S1 with 3 g of potassium hydroxide at a weight ratio of 4:3, and place it in a mortar for thorough grinding to obtain a mixture of raw material and activator powder;

[0056] Step S3: Effectively introduce heteroatom source: Dissolve 0.8 g of melamine in hot deionized water to obtain a hot solution, and pour the mixture of raw material and activator powder in Step S2 into the hot solution, heat and stir until the water evaporates; specifically, the heating temperature is 90 °C and the stirring time is 4 h;

[0057] Step S4: High-temperature carbonization: Carbonize the mixture obtained in the last step of Step S3 at high temperature in an oxygen-deficient environment; specifically, put the mixture obtained in the last step of Step S3 into an alumina corundum crucible, then place it in a tube furnace, set the nitrogen purge flow rate to 150 mL / min, set the program to heat the tube furnace to the preset temperature of 900 °C at a heating rate of 5 °C / min, maintain this temperature for 3 h, and naturally cool after the program runs to completion;

[0058] Step S5: Wash and dry the doped porous carbon material: Wash and dry the product of Step S4 to obtain a nitrogen-doped porous carbon material. Specifically, transfer the cooled product in Step S4 to a beaker and add 200 milliliters of hydrochloric acid solution with a concentration of 2 mol / L to the beaker, and stir at room temperature for 24 hours. After the stirring ends, use a suction filtration device for filtration and repeatedly rinse the solid product with deionized water until the filtrate is neutral. Finally, put the washed black product into a drying oven at 150 °C for drying for 24 hours to obtain a nitrogen-doped porous carbon material, and the nitrogen-doped porous carbon material is used as a carbon dioxide adsorbent.

[0059] Figure 1The microscopic morphology (SEM) of the waste biomass grapefruit peel raw material is shown. It can be observed from the figure that the surface of the grapefruit peel is wrinkled, and no obvious pore characteristics are found. This shows that the grapefruit peel precursor lacks a pore structure and its surface has rough and wrinkled characteristics. Figure 2 The microscopic morphology of the nitrogen-doped porous carbon material obtained by high-temperature carbonization of grapefruit peel in an oxygen-deficient environment is shown. Compared with the morphology of the precursor grapefruit peel, it presents a sponge-like pore structure of nanometer size. This is because the nitrogen in melamine will be converted into ammonia or nitrogen oxides during the high-temperature carbonization process, which further promotes the formation of pores. The formation of this pore structure increases the specific surface area of ​​the waste biomass grapefruit peel, which indicates that through the carbonization / activation method in an oxygen-deficient environment, pores can be formed inside the waste biomass grapefruit peel, thereby effectively increasing its specific surface area. Elemental analysis (EA) shows that the nitrogen-doped porous carbon material has a nitrogen content of 0.5wt%, indicating that nitrogen atoms are effectively incorporated into the carbon material skeleton.

[0060] like Figure 3 As shown in the figure, based on the test results of nitrogen-doped porous carbon materials for CO2 adsorption at room temperature (25°C), it is observed that when the pressure is between 0 and 1 bar, the adsorption capacity of nitrogen-doped porous carbon materials for carbon dioxide is significantly enhanced. In particular, when the pressure reaches one atmosphere, the adsorption capacity of CO2 reaches 105.3 cm 3 / g, converted to 4.7mmol / g.

[0061] like Figure 4 The X-ray powder diffraction pattern of Example 1 is shown in Figure 4 It can be seen that the nitrogen-doped porous carbon material exhibits significant broad peaks at 2θ angles of about 24° and 43°, indicating that the material has an amorphous porous carbon structure. Figure 4 No other impurity peaks were observed, indicating that the carbon material after impregnation and washing with hydrochloric acid does not contain other impurities.

[0062] like Figure 5 As shown, it is the Raman spectrum of Example 1, Figure 5 It can be seen that 1330cm on the x-axis -1 and 1590cm -1 There are two significant broad diffraction peaks at , which correspond to the D peak and G peak of nitrogen-doped porous carbon materials, respectively, indicating that the sample has a certain degree of graphitization structure and defect structure. G / I D The smaller the value, the lower the degree of graphitization of the carbon material, that is, it has more defective structures. It is calculated that the I G / I D The value is 0.97, which is the same as that in Example 2 (IG / I D value is 1.03) and Example 3 (I G / I D The IG / ID value of Example 1 is smaller than that of Example 3 (value is 0.98), indicating that the nitrogen-doped porous carbon of Example 1 has more defective structures, can provide more adsorption sites, and shows that the nitrogen heteroatom functional groups brought by nitrogen doping play an enhanced role in the carbon dioxide adsorption process.

[0063] Example 2: Preparation of sulfur-doped porous carbon material

[0064] A preparation method of a heteroatom-doped porous carbon material for carbon dioxide adsorption includes the following steps:

[0065] Step S1: Dry and crush pomelo peel to obtain raw material powder;

[0066] Step S2: Mix waste biomass with activator: Mix 4 g of the raw material pomelo peel powder in Step S1 with 3 g of potassium hydroxide at a weight ratio of 4:3, and place it in a mortar for thorough grinding to obtain a raw material and activator powder mixture;

[0067] Step S3: Effectively introduce heteroatom source: Dissolve 0.8 g of sodium sulfide in hot deionized water to obtain a hot solution, and pour the raw material and activator powder mixture in Step S2 into the hot solution, heat and stir until the water evaporates; specifically, the heating temperature is 90 °C and the stirring time is 4 h;

[0068] Step S4: High-temperature carbonization: Carbonize the mixture obtained in the last step of Step S3 at high temperature in an anoxic environment; specifically, put the mixture obtained in the last step of Step S3 into an alumina corundum crucible, then place it in a tube furnace, set the nitrogen purge flow rate to 150 mL / min, set the program to heat the tube furnace to the preset temperature of 900 °C at a heating rate of 5 °C / min, keep this temperature for 3 h, and naturally cool after the program runs to completion;

[0069] Step S5: Clean and dry the doped porous carbon material: Clean and dry the product of Step S4 to obtain a nitrogen-doped porous carbon material. Specifically, transfer the cooled product in Step S4 to a beaker and add 200 mL of hydrochloric acid solution with a concentration of 2 mol / L to the beaker, stir at room temperature for 24 hours. After the stirring ends, use a suction filtration device for filtration and repeatedly rinse the solid product with deionized water until the filtrate is neutral. Finally, put the washed black product into a drying oven at 150 °C and dry for 24 hours to obtain a sulfur-doped porous carbon material, and the sulfur-doped porous carbon material is used as a carbon dioxide adsorbent.

[0070] The SEM image of the sulfur-doped porous carbon material shows an uneven pore structure, as Figure 6 shown. Although it has a nanoporous structure, compared with the nitrogen-doped porous carbon material, the latter obviously has a denser and more developed pore structure. Elemental analysis (EA) shows that the sulfur content in the sulfur-doped porous carbon material is as high as 3.2 wt%, indicating that sulfur heteroatoms are effectively incorporated into the carbon material skeleton; the elemental analysis also shows that the nitrogen content in the sulfur-doped porous carbon material is only 0.2 wt%.

[0071] As Figure 7 shown, based on the analysis of the test results of the CO2 adsorption of the sulfur-doped porous carbon material at room temperature (25 °C), when the pressure is between 0 and 1 bar, it is observed that the CO2 adsorption capacity of the sample is significantly enhanced. Especially under the condition that the pressure reaches one atmosphere, the CO2 adsorption amount reaches 69.4 cm 3 / g, which is converted to 3.1 mmol / g.

[0072] As Figure 8 shown, it is the X-ray powder diffraction pattern of Example 2. It can be seen from Figure 8 that the sulfur-doped porous carbon material exhibits significant broad peaks at positions where the 2θ angle is about 24° and 43°, indicating that the material has an amorphous porous carbon structure. In addition, no other impurity peaks are observed from Figure 8 , indicating that the carbon material after hydrochloric acid impregnation washing does not contain other impurities.

[0073] As Figure 9 shown, it is the Raman spectrum of Example 2. It can be seen from Figure 9 that there are two significant diffraction broad peaks at 1352 cm -1 and 1590 cm -1 on the x-axis, which respectively correspond to the D peak and G peak of the sulfur-doped porous carbon material, indicating that this sample has a certain degree of graphitized structure and defect structure. After calculation, the I G / I D value of the sulfur-doped porous carbon material is 1.03.

[0074] Example 3: Preparation of nitrogen-sulfur co-doped porous carbon material

[0075] A preparation method of a heteroatom-doped porous carbon material for CO2 adsorption, comprising the following steps:

[0076] Step S1: Dry and crush pomelo peel to obtain raw material powder;

[0077] Step S2. Mixing waste biomass with an activator: Mix 4 g of pomelo peel powder as the raw material in Step S1 with 3 g of potassium hydroxide at a weight ratio of 4:3, and place them in a mortar for thorough grinding to obtain a mixture of the raw material and the activator powder;

[0078] Step S3. Effectively introducing heteroatom sources: Dissolve 0.8 g of melamine and 0.8 g of sodium sulfide in hot deionized water to obtain a hot solution, and pour the mixture of the raw material and the activator powder in Step S2 into the hot solution, then heat and stir until the water evaporates; specifically, the heating temperature is 90 °C and the stirring time is 4 h;

[0079] Step S4. High-temperature carbonization: Carbonize the mixture obtained at the end of Step S3 at high temperature in an oxygen-deficient environment; specifically, put the mixture obtained at the end of Step S3 into an alumina corundum crucible, then place it in a tubular furnace, set the nitrogen purge flow rate to 150 mL / min, set the program to heat the tubular furnace at a heating rate of 5 °C / min to the preset temperature of 900 °C, maintain this temperature for 3 h, and let it cool naturally after the program runs to completion;

[0080] Step S5. Cleaning and drying of the doped porous carbon material: Clean and dry the product of Step S4 to obtain a nitrogen-doped porous carbon material. Specifically, transfer the cooled product in Step S4 to a beaker, add 200 mL of hydrochloric acid solution with a concentration of 2 mol / L to the beaker, stir at room temperature for 24 h. After the stirring ends, use a suction filtration device for filtration and repeatedly rinse the solid product with deionized water until the filtrate is neutral. Finally, put the washed black product into a drying oven at 150 °C for drying for 24 h to obtain a nitrogen-sulfur co-doped porous carbon material, and the nitrogen-sulfur co-doped porous carbon material is used as a carbon dioxide adsorbent.

[0081] Such as Figure 10 is the micrograph of the nitrogen-sulfur co-doped porous carbon material in Example 3. The microstructural morphology of the nitrogen-sulfur co-doped porous carbon material also shows a porous structure at the nanoscale, and the specific surface area at 800 °C is 1832 m 2 / g, indicating that the specific surface area of the waste biomass pomelo peel has been increased. The results of elemental analysis (EA) show that the percentage content of N in the nitrogen-sulfur co-doped porous carbon material is as high as 2.5 wt%, much higher than the N content (0.5 wt%) in the nitrogen-doped porous carbon material; while the percentage of S in the nitrogen-sulfur co-doped porous carbon material is 1.36 wt%, indicating that the two heteroatoms of nitrogen and sulfur are effectively incorporated into the carbon material framework. Figure 13 is the infrared spectrum (FT-IR) of the nitrogen-sulfur co-doped porous carbon material, indicating the types of functional groups contained in the nitrogen-sulfur co-doped porous carbon material, at 1050 - 1150 cm -1The absorption peak range corresponds to C-O; at 1650 - 1700 cm -1 The absorption peak range corresponds to C=O; at 2250 - 2300 cm -1 The absorption peak in the range corresponds to C-N; the C-H functional group appears at 2850 - 2960 cm -1 (alkyl) and 3000 - 3100 cm -1 (alkene / aromatic) absorption peak range; at approximately 1350 cm -1 corresponds to the N-O functional group; at approximately 620 cm -1 The absorption peak corresponds to the sulfonic acid group (-SO3H). The S=O in the sulfonic acid group can enhance the carbon dioxide adsorption capacity. Because the doping of heteroatoms in the carbon skeleton will form a defective structure, resulting in changes in the electronic structure of the carbon material and affecting the carbon dioxide adsorption performance. And the nitrogen-containing functional group will form basic adsorption sites to improve the adsorption capacity. Although the nitrogen-sulfur co-doped carbon material has excellent carbon dioxide performance, the results show that it is lower than the nitrogen-doped carbon material in Example 1 because there is a competitive behavior between the nitrogen functional group adsorption site and the sulfur functional group adsorption site.

[0082] As Figure 11 shown, based on the analysis of the test results of the nitrogen-sulfur co-doped porous carbon material for CO2 adsorption at room temperature (25 °C), when the pressure is between 0 and 1 bar, it is observed that the carbon dioxide adsorption capacity of the sample is significantly enhanced. Especially under the condition that the pressure reaches one atmosphere, the adsorption amount of CO2 reaches 71.7 cm 3 / g, which is converted to 3.2 mmol / g.

[0083] As Figure 12 shown, it is the X-ray powder diffraction pattern of Example 3. It can be Figure 12 seen that the nitrogen-sulfur co-doped porous carbon material shows significant broad peaks at positions where the 2θ angle is approximately 24° and 43°, indicating that the material has an amorphous porous carbon structure. In addition, no other impurity peaks are observed from Figure 12 , indicating that the nitrogen-sulfur co-doped carbon material after being impregnated and washed with hydrochloric acid does not contain other impurities.

[0084] As Figure 14 shown, it is the Raman spectrum of Example 3. It can be Figure 14 seen that there are two significant diffraction broad peaks at 1350 cm on the x-axis -1 and 1593 cm -1 respectively, which correspond to the D peak and G peak of the nitrogen-sulfur co-doped porous carbon material. This indicates that this sample has a certain degree of graphitized structure and defective structure. After calculation, the I G / I D value of the nitrogen-sulfur co-doped porous carbon material is 0.98.

[0085] It should be understood that although this specification is described according to various embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0086] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a heteroatom-doped porous carbon material for carbon dioxide adsorption, characterized in that: The steps include: Step S1, drying and crushing the waste biomass: drying and crushing the waste biomass to obtain raw material powder; Step S2, mixing the waste biomass with the activator: mixing the raw material powder in step S1 with the activator, and grinding them sufficiently to obtain a raw material and activator powder mixture; Step S3, effectively introducing heteroatom sources: dissolving one or more heteroatom sources in hot deionized water to obtain a hot solution, and pouring the mixture of the raw materials and the activator powder in step S2 into the hot solution, heating and stirring until the water evaporates; Step S4, high temperature carbonization: carbonizing the mixture obtained in step S3 at high temperature in an oxygen-deficient environment; Step S5, washing and drying the doped porous carbon material: washing and drying the product of step S4 to obtain a heteroatom-doped porous carbon material for carbon dioxide adsorption.

2. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The waste biomass in step S1 includes fruit shells or peels.

3. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 2, characterized in that: The waste biomass includes one or more of grapefruit peel, tangerine peel, orange peel, sugarcane peel or coconut shell.

4. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The activator in step S2 includes one or a combination of two of potassium hydroxide, zinc chloride, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium oxalate, and sodium oxalate; The raw material powder and the activator are mixed at a weight ratio of 1:0.5 to 1:1.

5.

5. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The heteroatom source in step S3 includes one or a combination of sulfur-containing chemical reagents, nitrogen-containing chemical reagents, and phosphorus-containing chemical reagents; The sulfur-containing chemical reagent includes one or a combination of sodium sulfide and potassium sulfide; the nitrogen-containing chemical reagent includes one or a combination of melamine, urea, ammonium carbonate, ammonium bicarbonate, ammonium sulfate and imidazole compounds; The phosphorus-containing chemical reagent includes one or a combination of two of phosphoric acid, phosphorous acid, diammonium phosphate and hypophosphorous acid; The mass of the heteroatom source is 20% to 80% of the raw material powder.

6. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The heating and stirring temperature in step S3 is 60-120 degrees, and the heating and stirring time is 2-12 hours.

7. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The oxygen-deficient environment in step S4 refers to carbonization under an inert gas atmosphere; the inert gas purge volume is 50-200 mL / min; the high temperature refers to a temperature of 700-1000 degrees; the heating rate is 5°C / min, and the insulation time is 1-5 hours.

8. The method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 1, characterized in that: The cleaning in step S5 includes soaking in an acidic solution, followed by suction filtration and washing the product with deionized water until the filtrate is neutral, and finally drying; The acidic solution is HCl or H2SO4 solution with a concentration of 2 mol / L; The drying temperature is 100-200°C and the drying time is 24 hours.

9. A heteroatom-doped porous carbon material for carbon dioxide adsorption, characterized in that: It is prepared according to the method for preparing heteroatom-doped porous carbon material for carbon dioxide adsorption according to any one of claims 1-8.

10. Use of the heteroatom-doped porous carbon material for carbon dioxide adsorption according to claim 9 in a carbon dioxide adsorbent.

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