A method for preparing and applying porous adsorbent materials

Abstract

This invention discloses a method for preparing and applying porous adsorbent materials, relating to the field of environmental protection technology. The invention first modifies biomass with organic nitrogen compounds to obtain nitrogen-doped materials; then, it modifies the nitrogen-doped materials with a chemical activator to obtain intermediate products; finally, it obtains porous adsorbent materials through pyrolysis. This novel porous adsorbent material not only possesses abundant highly reactive active groups such as hydroxyl, carboxyl, and amine groups, but also has a large specific surface area (1500-1800 m²). 2 The material exhibits excellent adsorption performance for CO2 and VOCs. This invention utilizes internationally recognized "zero-carbon" renewable agricultural and forestry biomass as raw material to prepare porous adsorption materials. This not only realizes the resource utilization of biomass but also applies it to the adsorption and treatment of CO2 and VOCs in industrial flue gas, resulting in significant environmental and economic benefits and broad application prospects in the field of industrial flue gas treatment.

Description

Technical Field

[0001] This study relates to a method for preparing and applying porous adsorbent materials, which belongs to the field of environmental protection technology. Background Technology

[0002] With the acceleration of global industrialization, the concentration of greenhouse gases in the atmosphere is constantly increasing, especially CO2, which has a profound impact on climate change. At the same time, various industrial production processes and transportation release large amounts of VOCs, which are not only harmful to human health but also a major cause of photochemical smog and secondary organic aerosols. Therefore, developing high-performance adsorption materials is crucial for the effective removal of CO2 and VOCs from the air.

[0003] Traditional activated carbon is widely used for gas adsorption due to its high specific surface area and good physicochemical stability. However, its adsorption efficiency for specific pollutants such as CO2 and VOCs still needs further improvement. As an emerging carbonaceous adsorbent, biochar possesses a good pore structure, abundant surface functional groups, and high inorganic mineral content, making it suitable for environmental management and ecological restoration. Biochar has been widely used in the remediation of emerging pollutants in soil and water, the mitigation of greenhouse gases, and the reduction of volatile organic compound (VOC) emissions, showing promising application prospects. Many parameters can be used to describe the properties of biochar, such as pore structure, surface functional groups, inorganic mineral content, VOC content, particle size, electrical conductivity, catalytic performance, aromaticity, hydrophobicity, and hydrophilicity. Among these, pore structure has a significant impact on the application of biochar, especially its adsorption capacity. For example, the micropores of biochar facilitate the adsorption of small molecule pollutants. In recent years, studies have found that introducing heteroatoms such as nitrogen can significantly improve the surface properties and electronic structure of carbon materials, thereby enhancing their affinity and selectivity for specific gas molecules. Summary of the Invention

[0004] To address the issues of high cost and poor stability in existing technologies for treating CO2 and VOCs in industrial flue gas, the present invention aims to provide a porous adsorbent material, its preparation method, and its application in industrial flue gas. The prepared adsorbent has high nitrogen content and specific surface area, and exhibits good adsorption performance for CO2 and VOCs.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A method for preparing a porous adsorbent material, characterized by comprising the following steps:

[0007] S1: Mix agricultural and forestry biomass and organic nitrogen compounds evenly, heat and stir to 100-200℃, and keep the temperature constant until the system becomes viscous to obtain nitrogen-doped materials;

[0008] S2: Add the nitrogen-doped material and chemical activator to water, mix evenly, and dry in an oven at 80-120°C to obtain an intermediate product;

[0009] S3: The intermediate product is pyrolyzed at 600℃~900℃ to obtain the porous adsorption material.

[0010] The technical concept of this invention is as follows: This invention incorporates organic nitrogen compounds into agricultural and forestry biomass to generate nitrogen-doped materials, which are then mixed with a chemical activator and carbonized at 600℃~900℃, followed by alkali melting to form a large number of porous structures, thus obtaining a porous adsorbent material. The prepared adsorbent material has a large specific surface area and good adsorption performance.

[0011] In the above preparation method, the agricultural and forestry biomass is at least one of crop straw, forestry residues, fruit shells, sugarcane bagasse, and vegetable residues.

[0012] The organic nitrogen compound is at least one of urea, melamine, polyacrylonitrile, ethylenediamine, aniline, and triethanolamine.

[0013] If there are two or more types of agricultural and forestry biomass, they can be mixed in any proportion.

[0014] Preferably, the mass ratio of the agricultural and forestry biological mass to the organic nitrogen compound is 2:1 to 5:1.

[0015] The chemical activator is at least one of potassium hydroxide, sodium hydroxide, phosphoric acid, zinc chloride, potassium carbonate, and sulfuric acid; and / or

[0016] Preferably, the mass ratio of the nitrogen-doped material to the chemical activator is (1-2):1; and / or

[0017] Preferably, the molar ratio of the chemical activator to water is 1:(45-300);

[0018] Preferably, the heating rate of the pyrolysis is 1–5 °C / min; and / or

[0019] The pyrolysis time is 30 to 100 minutes.

[0020] In the above preparation method, the CO2 and VOCs adsorbent material is a porous carbon material.

[0021] Furthermore, the specific surface area of ​​the porous adsorbent material is 1500–1800 m². 2 / g, such as 1679m 2 / g.

[0022] Secondly, the present invention provides porous adsorbent materials prepared by the method described in any of the above-mentioned methods.

[0023] Thirdly, the present invention provides the application of the porous adsorption material in the adsorption and treatment of CO2 and / or VOCs in industrial flue gas.

[0024] In the above applications, the adsorption conditions are normal temperature and pressure.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The specific surface area of ​​the adsorbent can reach 1500-1800 m². 2 / g;

[0027] (2) It has good adsorption properties;

[0028] (3) The total adsorption capacity of the adsorbent for CO2 and VOCs can reach 1 to 5 mmol / g.

[0029] Attached Figure

[0030] Figure 1 This is a SEM image of the porous adsorbent material prepared in Example 1 of the present invention;

[0031] Figure 2 This is a pore size distribution diagram of the porous adsorbent material prepared in Example 1 of the present invention;

[0032] Figure 3 The adsorption breakthrough curves of the porous adsorbent material prepared in Example 1 of this invention for CO2 and acetone are shown. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. The given embodiments are merely illustrative and not intended to limit the scope of the invention. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0034] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0035] Example 1

[0036] This invention provides a porous carbon adsorbent material, prepared from wheat straw and sawdust in a mass ratio of 7:3, a chemical activator in a molar ratio of 1:137, and water, specifically including the following steps:

[0037] Mix 7.5g of wheat straw, 2.5g of sawdust, and 5g of melamine evenly, heat to 170℃, and stir at a constant temperature until it becomes viscous to obtain melamine-doped material.

[0038] The preparation of porous adsorbent materials using the above-mentioned melamine-doped material specifically includes the following steps:

[0039] Take 5g of the melamine-doped material prepared above, mix it evenly with 5g of sodium hydroxide particles, add it to 310mL of water, stir at room temperature for 4h, and then dry it in an oven at 100℃ to obtain an intermediate product. Heat the intermediate product to 700℃ in a nitrogen atmosphere at a heating rate of 3℃ / min and hold for 60min to obtain a carbonized material. Wash the carbonized material with deionized water until neutral, and then dry it in an oven at 60℃ to obtain a porous adsorbent material.

[0040] The scanning electron microscope (SEM) image of the porous adsorbent material prepared above is shown below. Figure 1 As shown in the figure, the porous adsorbent material prepared by this invention has a rich and uniformly dense honeycomb pore structure. The formation of this structure greatly increases the specific surface area and improves the adsorption performance, making it exhibit excellent performance in environmental purification and resource recycling.

[0041] The pore size distribution diagram of the porous adsorbent material prepared in this embodiment is shown below. Figure 2 As shown in the figure, the porous adsorbent material contains both micropores and mesopores, with micropores (<2 nm) being the predominant type and an average pore size of 0.55 nm, reaching the ultramicropore range (<1 nm). Ultramicropores exhibit stronger adsorption potential and thus demonstrate greater advantages in adsorption. Appropriate activation levels result in a superior microporous structure in the modified biochar, leading to higher adsorption performance.

[0042] The adsorption breakthrough curve of the porous adsorbent material prepared in this embodiment is as follows: Figure 3 As shown in the figure, even under conditions of low CO2 and acetone concentrations, the porous adsorbent material prepared in this invention still exhibits high adsorption performance for its two-component gases. Specifically, the adsorption capacity for CO2 is 1.25 mmol / g, and the adsorption capacity for acetone is 2.01 mmol / g.

[0043] Example 2

[0044] This invention provides a porous adsorbent material prepared from a chemical activator and water in a molar ratio of 1:200, specifically comprising the following steps:

[0045] Mix 10g of wheat straw and 5g of urea evenly, heat to 120℃, and stir at a constant temperature until it becomes viscous to obtain urea-doped material.

[0046] Take 5g of the urea-doped material prepared above, mix it evenly with 5g of potassium hydroxide granules, add it to 320mL of water, stir at room temperature for 4h, and then dry it in an oven at 100℃ to obtain an intermediate product. Heat the intermediate product to 800℃ in a nitrogen atmosphere at a heating rate of 5℃ / min and hold for 60min to obtain a carbonized material. Wash the carbonized material with deionized water until neutral, and then dry it in an oven at 60℃ to obtain a porous adsorbent material.

[0047] Example 3

[0048] This invention provides a porous adsorbent material prepared from a chemical activator and water in a molar ratio of 1:62, specifically comprising the following steps:

[0049] Mix 10g of sugarcane bagasse and 10g of urea evenly, heat to 120℃, and stir at a constant temperature until it becomes viscous to obtain urea-doped material.

[0050] Take 4g of the urea-doped material prepared above, mix it evenly with 3g of sodium hydroxide particles, add it to 140mL of water, stir at room temperature for 4h, and then dry it in an oven at 100℃ to obtain an intermediate product. Heat the intermediate product to 700℃ in a nitrogen atmosphere at a heating rate of 3℃ / min and hold for 90min to obtain a carbonized material. Wash the carbonized material with deionized water until neutral, and then dry it in an oven at 60℃ to obtain a porous adsorbent material.

[0051] Example 4

[0052] This invention provides a porous adsorbent material prepared from wheat straw and branches in a mass ratio of 1:1, a chemical activator in a molar ratio of 1:137, and water, specifically comprising the following steps:

[0053] Mix 4.2g of wheat straw, 4.2g of branches, and 8.4g of urea evenly, heat to 120℃, and stir at a constant temperature until it becomes viscous to obtain urea-doped material.

[0054] Take 6g of the urea-doped material prepared above, mix it evenly with 6g of sodium hydroxide particles, add it to 375mL of water, stir at room temperature for 4h, and then dry it in an oven at 100℃ to obtain an intermediate product. Heat the intermediate product to 700℃ in a nitrogen atmosphere at a heating rate of 3℃ / min and hold for 60min to obtain a carbonized material. Wash the carbonized material with deionized water until neutral, and then dry it in an oven at 60℃ to obtain a porous adsorbent material.

[0055] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A method for preparing a porous adsorbent material, characterized in that, Includes the following steps: S1: Mix agricultural and forestry biomass and organic nitrogen compounds evenly, heat and stir to 100~200℃, keep the temperature constant until the system becomes viscous, and obtain nitrogen-doped materials; The organic nitrogen compound is at least one of urea, melamine, polyacrylonitrile, ethylenediamine, aniline, and triethanolamine; S2: Add the nitrogen-doped material and chemical activator to water, mix evenly, and dry in an oven at 80~120℃ to obtain an intermediate product; S3: The intermediate product is pyrolyzed at 600℃~900℃ to obtain carbonized material; the carbonized material is washed with deionized water until neutral, and then dried in an oven at 60℃ to obtain porous adsorption material.

2. The method for preparing a porous adsorbent material as described in claim 1, characterized in that, The agricultural and forestry biomass is at least one of the following: crop straw, forestry residues, fruit shells, sugarcane bagasse, and vegetable residues.

3. The method for preparing a porous adsorbent material as described in claim 1, characterized in that, If there are two or more types of agricultural and forestry biomass, they can be mixed in any proportion. The mass ratio of agricultural and forestry biomass to organic nitrogen compounds is 2:1 to 5:

1.

4. The method for preparing a porous adsorbent material as described in claim 1, characterized in that, The chemical activator is at least one of potassium hydroxide, sodium hydroxide, phosphoric acid, zinc chloride, potassium carbonate, and sulfuric acid; and / or the mass ratio of the nitrogen-doped material to the chemical activator is (1~2):1; and / or the molar ratio of the chemical activator to water is 1:(45~300); The heating rate of the pyrolysis is 1~5℃ / min; and / or The pyrolysis time is 30~100min.

5. The application of the porous adsorbent material prepared by the preparation method according to any one of claims 1-4 in the adsorption and treatment of CO2 and / or VOCs in industrial flue gas.

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