Modified activated carbon material as well as preparation method and application thereof

Abstract

The invention relates to the field of adsorbents, and discloses a modified activated carbon material as well as a preparation method and application thereof. The material contains a copper metal organic framework, activated carbon and polyvinyl formal, is in a microbead shape, and has a large specific surface area and high sulfur capacity. The preparation method of the modified activated carbon material comprises the following steps: taking activated carbon which is prepared from a biomass raw material and is subjected to nitric acid dipping treatment as a substrate, loading a metal organic framework material, and then forming the metal organic framework material and a polymer raw material into microbeads by using a phase reversal method. According to the method, the whole process is high in controllability, metal components are introduced through a metal organic framework, metal active components are highly dispersed, and the adsorption performance is further enhanced; the prepared formed modified activated carbon material shows good sulfur dioxide adsorption performance and is convenient to use and recycle.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Chinese patent application 202410975826.3 filed on July 19, 2024, the contents of which are incorporated herein by reference. Technical Field

[0002] The invention relates to the field of adsorbents, and in particular to a modified activated carbon material and a preparation method and application thereof. Background Art

[0003] The rapid development of the energy industry has improved human life, but also brought environmental problems. Sulfur dioxide (SO2) is a colorless but pungent environmental pollutant gas. The SO2 emitted into the atmosphere by human activities mainly comes from the combustion process of sulfur-containing fuels and the flue gas generated in the industrial production process of sulfur-containing products, which is easy to cause air pollution and acid rain. Reducing sulfur dioxide emissions is one of the key points in solving environmental problems. At present, the most widely used desulfurization methods can be divided into wet flue gas desulfurization (WFGD), semi-dry flue gas desulfurization (SDFGD) and dry flue gas desulfurization (DFGD) according to whether water is involved in the desulfurization process and the dry and wet states of the desulfurizer and the by-products after desulfurization. Among them, the dry flue gas desulfurization process that adsorbs sulfur dioxide with adsorbents such as activated carbon is a simple and effective method for removing sulfur dioxide. It can avoid the wastewater generated in the wet process and the additional energy consumption of flue gas heating treatment. It has the advantages of less secondary pollution, renewable adsorbents and simple facility maintenance.

[0004] As the core of dry desulfurization process, adsorbents with large sulfur capacity are one of the research focuses. Activated carbon materials show excellent SO2 removal performance due to their huge specific surface area, developed microporous / mesoporous structure, excellent physical properties (high temperature resistance, strong hydrophobicity, stable mechanical strength) and chemical properties (acid and alkali resistance, rich surface functional groups). However, pure activated carbon generally has the disadvantages of small adsorption capacity, easy saturation and easy desorption. It needs to be modified to optimize the morphology and structure of activated carbon and improve sulfur capacity and adsorption effect; powdered activated carbon also has the disadvantages of being difficult to use and difficult to recycle. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of the prior art that the activated carbon has poor sulfur dioxide adsorption performance and is not easy to use, and to provide a modified activated carbon material and its preparation method and application. The modified activated carbon material is in the form of microbeads, which overcomes the disadvantage that the powdered activated carbon material is inconvenient to use, and contains a metal organic framework, activated carbon and polyvinyl formal, and the metal organic framework further improves the adsorption performance of the modified activated carbon material for sulfur dioxide. The preparation method introduces metal active components into the metal organic framework to achieve the modification of the activated carbon, and the loaded metal organic framework is highly dispersed and evenly distributed, which is conducive to contact with sulfur dioxide and further improves the adsorption performance; it is formed into microbeads by a phase inversion method, and the morphology structure of the modified activated carbon material can be effectively controlled by adjusting the process conditions, so that the modified activated carbon material is easy to use and recycle.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a modified activated carbon material on the one hand, wherein the particles of the modified activated carbon material are in the form of microbeads, and the modified activated carbon material contains activated carbon, a metal organic framework and polyvinyl formal, and relative to 100 parts by weight of the activated carbon, the content of the metal organic framework is 0.1-5 parts by weight, and the content of the polyvinyl formal is 1-30 parts by weight.

[0007] Preferably, relative to 100 parts by weight of the activated carbon, the content of the metal organic framework is 0.5-2 parts by weight, and the content of the polyvinyl formal is 5-20 parts by weight.

[0008] Preferably, the metal organic framework is a copper metal organic framework.

[0009] Preferably, the specific surface area of ​​the modified activated carbon material is 370-550m 2 / g, sulfur capacity is 450-860mg / g.

[0010] A second aspect of the present invention provides a method for preparing a modified activated carbon material, the method comprising the following steps: (1) subjecting biomass raw materials to pyrolysis and carbonization to obtain biochar; (2) mixing the biomass charcoal with nitric acid for impregnation treatment, and then calcining the mixture to obtain activated carbon; (3) mixing the activated carbon with a solution containing a metal organic framework to obtain modified activated carbon; (4) The modified activated carbon is mixed with a polyvinyl formal solution to obtain a slurry, and then the slurry is formed by a phase inversion method.

[0011] Preferably, in step (1), the pyrolysis carbonization treatment is carried out under an inert atmosphere, and the conditions of the pyrolysis carbonization treatment include: a temperature of 500-600° C. and a time of 60-120 min.

[0012] Preferably, the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere.

[0013] Preferably, the method according to any one of claim 5 is characterized in that, in step (1), before the biomass raw material is subjected to pyrolysis and carbonization treatment, the biomass raw material is crushed, ground and sieved to obtain a powder with a particle size of 50-200 mesh.

[0014] Preferably, the biomass raw material is coconut shell and / or pine wood.

[0015] Preferably, in step (2), the nitric acid is used in the form of an aqueous solution, and the mass ratio of the nitric acid solution to the biochar is 5-7:1.

[0016] Preferably, the concentration of the nitric acid solution is 25-35wt%.

[0017] Preferably, the calcination treatment conditions include: temperature of 750-950° C. and time of 1.5-2.5 h.

[0018] Preferably, in step (3), the mass volume ratio of the activated carbon to the solution containing the metal organic framework is 1 g: 18-22 mL.

[0019] Preferably, in step (3), the metal organic framework is a copper-based metal organic framework, preferably MFM-170.

[0020] Preferably, the method further comprises preparing the copper-based metal organic framework according to the following steps: 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) and copper salt are dissolved in an aqueous solution containing N,N-dimethylformamide, and concentrated nitric acid is added for acidification, followed by heating.

[0021] Preferably, the molar ratio of the 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) to the copper salt is 1:1.5-2 in terms of Cu.

[0022] Preferably, in step (4), the mass volume ratio of the modified activated carbon to the polyvinyl formal solution is 1 g: 2.5-4.5 mL.

[0023] Preferably, the concentration of the polyvinyl formal solution is 3-8wt%.

[0024] Preferably, in step (4), the process of molding the slurry by phase inversion method comprises: The slurry is dripped into water drop by drop to solidify into micro beads, and then the formed micro beads are separated from the solid and liquid and dried.

[0025] The third aspect of the present invention provides a modified activated carbon material prepared by the aforementioned method.

[0026] A fourth aspect of the present invention provides the use of the aforementioned modified activated carbon material in the adsorption of sulfur dioxide.

[0027] According to the modified activated carbon material of the present invention, the material contains a metal organic framework, activated carbon and polyvinyl formal and is in the form of microbeads, wherein the metal organic framework, especially the copper metal organic framework, can further enhance the material's ability to adsorb sulfur dioxide. The microbead shape improves the material's structural stability while facilitating use and recycling. The material has a large specific surface area and sulfur capacity, which is beneficial to the adsorption of sulfur dioxide.

[0028] According to the preparation method of the modified activated carbon material of the present invention, the metal active component is introduced into the metal organic framework, especially the copper-based metal organic framework, to realize the modification of the activated carbon. The loaded metal organic framework is highly dispersed and evenly distributed, which is beneficial to the contact with sulfur dioxide, and further improves the overall adsorption performance of the material. The modified activated carbon material is formed into microbeads by the phase inversion method, and the morphology structure of the modified activated carbon material can be effectively controlled by adjusting the process conditions, so that the modified activated carbon material is easy to use and recycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process of preparing the modified activated carbon material provided by the present invention.

[0030] Figure 2 It is a short-term sulfur dioxide adsorption efficiency diagram of the modified activated carbon material provided by the present invention.

[0031] Figure 3 It is a graph of the long-term sulfur dioxide adsorption efficiency of the modified activated carbon material provided by the present invention. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] The present invention provides a modified activated carbon material, the particles of which are in the form of microbeads. The modified activated carbon material contains activated carbon, a metal organic framework and polyvinyl formal, and relative to 100 parts by weight of the activated carbon, the content of the metal organic framework is 0.1-5 parts by weight, and the content of the polyvinyl formal is 1-30 parts by weight.

[0035] In the modified activated carbon material described in the present invention, preferably, the content of the metal organic framework is 0.5-2 parts by weight, more preferably 0.8-1.5 parts by weight, relative to 100 parts by weight of the activated carbon; the content of the polyvinyl formal is 5-20 parts by weight, more preferably 8-15 parts by weight.

[0036] In the present invention, the component contents within the above range are selected to form stable micro-beads while ensuring the performance of adsorbing sulfur dioxide, which is conducive to obtaining better adsorption performance and reusability.

[0037] In the modified activated carbon material of the present invention, preferably, the metal organic framework is a copper metal organic framework. In the present invention, the selection of a copper metal organic framework is beneficial to further improve the adsorption capacity of sulfur dioxide.

[0038] In the modified activated carbon material of the present invention, preferably, the specific surface area of ​​the modified activated carbon material is 370-550m 2 / g, sulfur capacity is 450-860mg / g.

[0039] The modified activated carbon material according to the present invention has a larger specific surface area and a higher sulfur capacity, which is conducive to obtaining better sulfur dioxide adsorption performance, and is in the form of microbeads, which is more conducive to practical use and recycling than traditional powdered activated carbon materials.

[0040] The method for preparing the modified activated carbon material of the present invention comprises the following steps: (1) subjecting biomass raw materials to pyrolysis and carbonization to obtain biochar; (2) mixing the biomass charcoal with nitric acid for impregnation treatment, and then calcining the mixture to obtain activated carbon; (3) mixing the activated carbon with a solution containing a metal organic framework to obtain modified activated carbon; (4) The modified activated carbon is mixed with a polyvinyl formal solution to obtain a slurry, and then the slurry is formed by a phase inversion method.

[0041] In the method described in the present invention, preferably, in step (1), the pyrolysis carbonization treatment is carried out under an inert atmosphere, and the conditions of the pyrolysis carbonization treatment include: a temperature of 500-600°C and a time of 60-120 min. More preferably, the conditions of the pyrolysis carbonization treatment include: a temperature of 520-580°C and a time of 70-110 min. Most preferably, the conditions of the pyrolysis carbonization treatment include: a temperature of 540-575°C and a time of 80-100 min. In the present invention, the above-mentioned pyrolysis carbonization conditions are selected to ensure that the biomass is fully carbonized and the desired biomass charcoal is obtained.

[0042] In the method of the present invention, preferably, the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere.

[0043] In the method of the present invention, preferably, in step (1), before subjecting the biomass raw material to pyrolysis and carbonization, the biomass raw material is crushed, ground and sieved to obtain a powder with a particle size of 50-200 mesh. More preferably, the particle size of the crushed biomass raw material is 75-120 mesh.

[0044] In the method of the present invention, preferably, the biomass raw material is coconut shell and / or pine wood. In the present invention, the above biomass raw materials and sizes can be used to obtain more biomass charcoal through pyrolysis, and can be fully carbonized in a shorter time.

[0045] In the method of the present invention, preferably, in step (2), the nitric acid is used in the form of an aqueous solution, and the mass ratio of the nitric acid solution to the biochar is 5-7:1.

[0046] In the method described in the present invention, preferably, the concentration of the nitric acid solution is 25-35wt%.

[0047] In the present invention, the above-mentioned amount and concentration of nitric acid can be used to modify the surface of biochar, so that the surface of biochar obtains more oxygen-containing functional groups, which is beneficial to the subsequent loading of metal active components.

[0048] In the method described in the present invention, preferably, in step (2), the conditions for the calcination treatment include: a temperature of 750-950°C and a time of 1.5-2.5h. More preferably, the conditions for the calcination treatment include: a temperature of 800-900°C and a time of 1.75-2.5h. Most preferably, the conditions for the calcination treatment include: a temperature of 825-875°C and a time of 1.75-2.25h. In the present invention, the above-mentioned calcination treatment conditions are adopted to fully activate the biomass charcoal to obtain activated carbon, so that the obtained activated carbon has a rich pore structure and a large specific surface area, which is conducive to the final product also having a large specific surface area.

[0049] In the method of the present invention, preferably, in step (3), the mass volume ratio of the activated carbon material to the solution containing the metal organic framework is 1g:18-22mL, more preferably 1g:19-21mL, and most preferably 1g:19-20mL. In the present invention, the above-mentioned dosage ratio can make the activated carbon fully dispersed in the solution containing the metal organic framework, making the load more uniform, which is conducive to obtaining a modified activated carbon material with highly dispersed metal active components.

[0050] In the method of the present invention, preferably, in step (3), the metal organic framework is a copper-based metal organic framework, preferably MFM-170. In the present invention, the use of the above metal organic framework can introduce a copper metal organic framework with good adsorption capacity for sulfur dioxide, further improving the adsorption performance; the use of the metal organic framework can ensure the high dispersion of copper, so that when the loaded copper is converted into the copper metal organic framework, it can maintain a uniformly dispersed state, which is conducive to obtaining a modified activated carbon material with high sulfur capacity.

[0051] In the method of the present invention, preferably, the method further comprises preparing the copper-based metal organic framework according to the following steps: 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) and copper salt are dissolved in an aqueous solution containing N,N-dimethylformamide, and concentrated nitric acid is added for acidification, followed by heating.

[0052] In the method of the present invention, preferably, the molar ratio of the amount of the 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) to the copper salt is 1:1.5-2, more preferably 1:1.6-1.9. In the present invention, the above amount is used to obtain the MFM-170 metal organic framework and ensure full utilization of the raw materials.

[0053] In the method of the present invention, preferably, in step (4), the mass volume ratio of the modified activated carbon to the polyvinyl formal solution is 1 g: 2.5-4.5 mL, more preferably 1 g: 3.0-4.2 mL, and most preferably 1 g: 3.4-4.0 mL. In the present invention, the above amount can make the modified activated carbon fully dispersed in the solution and fully mixed with the polyvinyl formal, which is conducive to obtaining microbeads with uniformly distributed components.

[0054] In the method of the present invention, preferably, the polyvinyl formal solution is a solution obtained by dissolving polyvinyl formal in N,N-dimethylformamide at 70-90°C.

[0055] In the method of the present invention, preferably, the concentration of the polyvinyl formal solution is 3-8wt%, more preferably 4-7wt%, most preferably 5-6wt%.

[0056] In the method of the present invention, preferably, in step (4), after the modified activated carbon is mixed with the polyvinyl formal solution, the viscosity of the mixed solution can be increased to 900-1150 g / (m∙s) by further evaporating N,N-dimethylformamide as a solvent, which is beneficial to the rapid molding of microbeads in the phase inversion method.

[0057] In the method of the present invention, preferably, in step (4), the process of molding the slurry by phase inversion method comprises: The slurry is dripped into water drop by drop to solidify into micro beads, and then the formed micro beads are separated from the solid and liquid and dried.

[0058] In the method of the present invention, preferably, in step (4), the slurry is dripped into a water tank filled with water through a syringe needle, and a jet device formed by a T-shaped connector and a diaphragm is arranged near the syringe needle. The jet device can be adjusted to allow air flow to pass through the needle tip, thereby increasing resistance and forming smaller microbeads.

[0059] In the present invention, the phase inversion method is used to rapidly shape the slurry into microbeads after the slurry is dropped into water, and the morphology and structure of the obtained microbeads can be adjusted by adjusting the ratio of the modified activated carbon and the polyvinyl formal solution in the slurry.

[0060] In a specific embodiment, Figure 1 As shown, the preparation method of the present invention comprises the following steps: (1) Pyrolyzing and carbonizing the biomass in an inert atmosphere at 500-600°C for 60-120 minutes to obtain biochar; (2) The biochar is impregnated with a 25-35wt% nitric acid solution at 70-90°C for 0.5-3h, then rinsed with water until neutral, dried at 100-150°C, and then calcined at 750-950°C for 0.5-2h to obtain activated carbon; wherein the mass ratio of the nitric acid to the carbonized solid is 5-7:1; (3) Dissolving 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) (i.e., H4L) and copper salt in an aqueous solution containing N,N-dimethylformamide, adding concentrated nitric acid for acidification, and then reacting at 70-90° C. for 12-20 hours to obtain a solution containing a metal organic framework; wherein the molar ratio of the H4L to the copper salt in terms of Cu is 1:1.5-2, the copper salt is one or more of Cu(NO3)2∙2.5H2O, Cu(NO3)2∙5H2O and Cu(NO3)2, the ratio of N,N-dimethylformamide to water in the aqueous solution containing N,N-dimethylformamide is 4-6:1, and the volume ratio of the concentrated nitric acid to the aqueous solution containing N,N-dimethylformamide is 1:150-170; The activated carbon obtained in step (2) is mixed with the solution containing the metal organic framework in a mass volume ratio of 1 g of activated carbon to 18-22 mL of the solution containing the metal organic framework, and then the obtained mixture is separated into solid and liquid, and the obtained solid is washed with hot N,N-dimethylformamide and dried at 70-90° C. for 6-18 hours to obtain modified activated carbon; (4) Polyvinyl formal (PVFM) is mixed with N,N-dimethylformamide at 70-90° C. to obtain a polyvinyl formal solution with a mass fraction of 3-8 wt %, and the modified activated carbon obtained in step (3) is mixed with the polyvinyl formal solution at a mass volume ratio of 1 g of modified activated carbon: 2.5-4.5 mL of the polyvinyl formal solution to obtain a slurry, and then the slurry is dripped into water dropwise to solidify to form microbeads, and then the formed microbeads are separated from the solid and liquid, and dried at 80-100° C. for 12-24 h.

[0061] The preparation method of the modified activated carbon material of the present invention uses a metal organic framework containing Cu as a copper source and activated carbon modified by nitric acid as a substrate, obtains a modified activated carbon loaded with a copper metal organic framework through calcination, and then mixes it with a polyvinyl formal solution, and forms it into microbeads through a phase inversion method, and introduces active components in the form of a metal organic framework, so that the active components can be highly dispersed after calcination, providing more adsorption active centers, which is beneficial to improving adsorption performance; when forming by the phase inversion method, by adjusting the concentration of different components, formed microbeads with different shapes, sizes, densities and specific surface areas can be prepared, which is beneficial to adjust the obtained products according to actual needs.

[0062] The modified activated carbon material prepared by the aforementioned method of the present invention has highly dispersed adsorption active centers and a stable and controllable morphology structure. The loading modification of the Cu-containing metal organic framework helps to further improve the adsorption performance. It is easy to use and recycle by being formed into microbeads, thereby improving the reusability during actual use.

[0063] The modified activated carbon material described in the present invention is used in the adsorption of sulfur dioxide. The modified activated carbon prepared with a Cu-containing metal organic framework as a copper source adsorbs sulfur dioxide at 120°C, an adsorption time of 20 hours, a total flow rate of 30 mL / min, 2000 ppm SO2, and 6% O2. The adsorption amount reaches 850.8 mg / g, showing good sulfur dioxide adsorption performance.

[0064] In the present invention, the sulfur capacity refers to the adsorption capacity of sulfur dioxide within a fixed time.

[0065] The modified activated carbon material and its preparation method and application of the present invention are further illustrated by examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0066] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0067] Example 1 (1) The coconut shell was crushed, ground and sieved to obtain coconut shell powder with a particle size of 100 mesh, which was then placed in a furnace, introduced with 500 mL / min of N2, pyrolyzed and carbonized at 550°C for 90 min, and then continued to be introduced with 200 mL / min of N2 to cool to room temperature to obtain biochar; (2) 40 g of the biochar obtained in step (1) was immersed in 200 mL of a 30 wt% nitric acid solution in a water bath at 80 ° C for 2 h, then rinsed with deionized water until neutral, dried at 120 ° C, 10 g of the dried biochar was placed in a furnace, 500 mL / min of N2 was introduced as a protective gas, the temperature was raised to 850 ° C at a rate of 10 ° C / min, and calcined for 2 h to obtain activated carbon; (3) Weigh 192 mg of 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) (i.e., H4L) and 298 mg of Cu(NO3)2∙3H2O and dissolve them in 48 mL of an aqueous solution containing N,N-dimethylformamide (DMF) (volume ratio DMF:H2O=5:1), and add 0.3 mL of concentrated nitric acid for acidification. Transfer the resulting solution to a Schott bottle and react at 80°C for 18 h to obtain a solution containing MFM-170; Add 2.5 g of the activated carbon obtained in step (2) to the solution containing MFM-170, perform ultrasonic vibration for 20 min, and then let it stand for 10 min to separate the obtained mixture into solid and liquid. Then, wash the obtained solid with hot N,N-dimethylformamide and dry it in an oven at 70° C. for 18 h to obtain modified activated carbon. (4) Dissolve 1 g of polyvinyl formal (PVFM) in 18 mL of N,N-dimethylformamide at 80 °C, add 6 g of the modified activated carbon obtained in step (3) to the polyvinyl formal solution to obtain a slurry, pump the slurry into a syringe at a rate of 1 mL / min, and drip it into a sink filled with deionized water through the syringe needle, then separate the microbeads that instantly harden and form when dripped into the sink, and dry them at 90 °C for 18 h. The obtained modified activated carbon material is recorded as CuAC-1.

[0068] Example 2 (1) The coconut shell was crushed, ground and sieved to obtain coconut shell powder with a particle size of 125 mesh, which was then placed in a furnace, introduced with 450 mL / min of N2, pyrolyzed and carbonized at 500 °C for 60 min, and then continued to be introduced with 150 mL / min of N2 to cool to room temperature to obtain biochar; (2) 40 g of the biochar obtained in step (1) was immersed in 200 mL of a 35 wt% nitric acid solution in a water bath at 70 ° C for 2.5 h, then rinsed with deionized water until neutral, dried at 150 ° C, 10 g of the dried biochar was placed in a furnace, 450 mL / min of N2 was introduced as a protective gas, the temperature was raised to 850 ° C at a rate of 10 ° C / min, and calcined for 2 h to obtain activated carbon; (3) Weigh 144 mg of 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) (i.e., H4L) and 223.5 mg of Cu(NO3)2∙2.5H2O and dissolve them in 48 mL of an aqueous solution containing N,N-dimethylformamide (DMF) (volume ratio DMF:H2O=5:1), and add 0.3 mL of concentrated nitric acid for acidification. Transfer the resulting solution to a Schott bottle and react at 80°C for 20 h to obtain a solution containing MFM-170; Add 5 g of the activated carbon obtained in step (2) to the solution containing MFM-170, perform ultrasonic vibration for 30 min, and then let it stand for 15 min to separate the obtained mixture into solid and liquid. Then, wash the obtained solid with hot N,N-dimethylformamide and dry it in an oven at 80° C. for 12 h to obtain modified activated carbon. (4) 1.2 g of polyvinyl formal (PVFM) was dissolved in 18 mL of N,N-dimethylformamide at 90 °C, and 5 g of the modified activated carbon obtained in step (3) was added to the polyvinyl formal solution to obtain a slurry. The slurry was pumped into a syringe at a rate of 1 mL / min and dripped into a sink filled with deionized water through the syringe needle. The microbeads that instantly hardened and formed when dripped into the sink were separated and dried at 100 °C for 12 h. The modified activated carbon material obtained was recorded as CuAC-2.

[0069] Example 3 (1) The coconut shell was crushed, ground and sieved to obtain coconut shell powder with a particle size of 150 mesh, which was then placed in a furnace, introduced with 350 mL / min of N2, pyrolyzed and carbonized at 600 °C for 120 min, and then continued to be introduced with 100 mL / min of N2 and cooled to room temperature to obtain biochar; (2) 40 g of the biochar obtained in step (1) was immersed in 200 mL of a 30 wt% nitric acid solution in a water bath at 90 ° C for 1.5 h, then rinsed with deionized water until neutral, dried at 120 ° C, 10 g of the dried biochar was placed in a furnace, 450 mL / min of N2 was introduced as a protective gas, the temperature was raised to 800 ° C at a rate of 10 ° C / min, and calcined for 2 h to obtain activated carbon; (3) Weigh 230.4 mg of 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) (i.e., H4L) and 357.6 mg of Cu(NO3)2∙3H2O and dissolve them in 48 mL of an aqueous solution containing N,N-dimethylformamide (DMF) (volume ratio DMF:H2O=5:1), and add 0.3 mL of concentrated nitric acid for acidification. Transfer the resulting solution to a Schott bottle and react at 85°C for 18 h to obtain a solution containing MFM-170; Add 2.5 g of the activated carbon obtained in step (2) to the solution containing MFM-170, perform ultrasonic vibration for 20 min, and then let it stand for 15 min to separate the obtained mixture into solid and liquid. Then, wash the obtained solid with hot N,N-dimethylformamide and dry it in an oven at 90° C. for 10 h to obtain modified activated carbon. (4) 0.8 g of polyvinyl formal (PVFM) was dissolved in 18 mL of N,N-dimethylformamide at 70 °C, and 5 g of the modified activated carbon obtained in step (3) was added to the polyvinyl formal solution to obtain a slurry. The slurry was pumped into a syringe at a rate of 1 mL / min and dripped into a sink filled with deionized water through the syringe needle. The microbeads that instantly hardened and formed when dropped into the sink were separated and dried at 80 °C for 18 h. The modified activated carbon material obtained was recorded as CuAC-3.

[0070] Comparative Example 1 A modified activated carbon material was prepared according to the method of Example 1, except that in step (3), a solution containing MFM-170 was not prepared, but an aqueous solution of Cu(NO3)2∙3H2O was used instead of the solution containing MFM-170 as the copper source to prepare the modified activated carbon. The obtained modified activated carbon material was recorded as D1.

[0071] Comparative Example 2 A modified activated carbon material was prepared according to the method of Example 2, except that in step (3), a solution containing MFM-170 was not prepared, but an aqueous solution of Cu(NO3)2∙2.5H2O was used as a copper source instead of a solution containing MFM-170 to prepare the modified activated carbon. The obtained modified activated carbon material was recorded as D2.

[0072] Comparative Example 3 A modified activated carbon material was prepared according to the method of Example 3, except that in step (3), a solution containing MFM-170 was not prepared, but an aqueous solution of Cu(NO3)2∙3H2O was used as a copper source instead of a solution containing MFM-170 to prepare the modified activated carbon. The obtained modified activated carbon material was recorded as D3.

[0073] Test Example 1 The specific surface areas of the modified activated carbon materials CuAC-1 to CuAC-3 and D1 to D3 prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were tested by the BET method. The results are shown in Table 1: Table 1

[0074] As shown in Table 1, the modified activated carbon material prepared by the method of the present invention has a larger specific surface area than the activated carbon material modified by copper salt impregnation, and the specific surface area can reach 542.9 m 2 / g, which is beneficial to expose more adsorption sites and obtain better adsorption performance.

[0075] Test Example 2 The short-term adsorption performance of sulfur dioxide of the modified activated carbon materials CuAC-1 to CuAC-3 and D1~D3 prepared in Examples 1-3 and Comparative Examples 1-3 was tested by a fixed bed method (based on Cu content, the modified activated carbon materials with the same Cu dosage were weighed for testing). The test conditions were: 120° C., adsorption time 2 h, total flow rate 30 ml / min, SO2 concentration 2000 ppm, O2 content 6%, and the adsorbent was placed in a quartz tube with a diameter of 7 mm and kept at a height of 2 cm; The results are shown in Table 2 and Figure 2 As shown: Table 2

[0076] From Table 2 and Figure 2 It can be seen that the modified activated carbon material prepared by the method of the present invention has a higher SO2 adsorption capacity (i.e., sulfur capacity). Under the conditions of short-term testing, the SO2 adsorption capacity can reach 17.66 mg / g, showing good performance in adsorbing sulfur dioxide, which is significantly higher than the modified activated carbon material using copper salt solution as the copper source, indicating that using a metal organic framework as the copper source can utilize the confinement effect of the metal organic framework to make Cu highly dispersed, thereby further improving the adsorption performance.

[0077] Test Example 3 The long-term sulfur dioxide adsorption performance of the modified activated carbon materials CuAC-1 to CuAC-3 prepared in Examples 1-3 was tested by a fixed bed method (based on the Cu content, the modified activated carbon materials with the same Cu dosage were weighed for testing). The test conditions were: 120° C., adsorption time of 20 h, total flow rate of 30 ml / min, SO2 concentration of 2000 ppm, O2 content of 6%, and the adsorbent was placed in a quartz tube with a diameter of 7 mm and maintained at a height of 2 cm; The results are shown in Table 3 and Figure 3 As shown: Table 3

[0078] From Table 3 and Figure 3 It can be seen that the modified activated carbon material prepared by the method of the present invention has a higher SO2 adsorption capacity (i.e., sulfur capacity). Under the conditions of 20 hours of continuous adsorption, the efficiency remains 100%, and the SO2 adsorption capacity can reach 850.80 mg / g, showing good sulfur dioxide adsorption performance and a long service life, which is conducive to practical use.

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A modified activated carbon material, characterized in that: The particles of the modified activated carbon material are in the shape of microbeads. The modified activated carbon material contains activated carbon, a metal organic framework and polyvinyl formal. Relative to 100 parts by weight of the activated carbon, the content of the metal organic framework in terms of metal is 0.1-5 parts by weight, and the content of the polyvinyl formal is 1-30 parts by weight.

2. The modified activated carbon material according to claim 1, characterized in that Relative to 100 parts by weight of the activated carbon, the content of the metal organic framework in terms of metal is 0.5-2 parts by weight, and the content of the polyvinyl formal is 5-20 parts by weight.

3. The modified activated carbon material according to claim 1 or 2, characterized in that: The metal organic framework is a copper metal organic framework Preferably, the metal organic framework is MFM-170.

4. The modified activated carbon material according to any one of claims 1 to 3, characterized in that: The specific surface area of ​​the modified activated carbon material is 370-550m 2 / g, sulfur capacity is 450-860mg / g.

5. A method for preparing a modified activated carbon material, characterized in that: The method comprises the following steps: (1) subjecting biomass raw materials to pyrolysis and carbonization to obtain biochar; (2) mixing the biomass charcoal with nitric acid for impregnation treatment, and then calcining the mixture to obtain activated carbon; (3) mixing the activated carbon with a solution containing a metal organic framework to obtain modified activated carbon; (4) The modified activated carbon is mixed with a polyvinyl formal solution to obtain a slurry, and then the slurry is formed by a phase inversion method.

6. The method according to claim 5, characterized in that In step (1), the pyrolysis carbonization treatment is carried out under an inert atmosphere, and the conditions of the pyrolysis carbonization treatment include: a temperature of 500-600° C. and a time of 60-120 min; Preferably, the inert atmosphere is a nitrogen atmosphere and / or an argon atmosphere.

7. The method according to any one of claim 5, characterized in that In step (1), before the biomass raw material is subjected to pyrolysis and carbonization treatment, the biomass raw material is crushed, ground and sieved to obtain a powder with a particle size of 50-200 mesh; Preferably, the biomass raw material is coconut shell and / or pine wood.

8. The method according to claim 5, characterized in that In step (2), the nitric acid is used in the form of an aqueous solution, and the mass ratio of the nitric acid solution to the biochar is 5-7:1; Preferably, the concentration of the nitric acid solution is 25-35wt%.

9. The method according to claim 5, characterized in that In step (2), the calcination treatment conditions include: temperature of 750-950°C and time of 1.5-2.5h.

10. The method according to claim 5, characterized in that In step (3), the mass volume ratio of the activated carbon to the solution containing the metal organic framework is 1 g:18-22 mL.

11. The method according to claim 5 or 10, characterized in that: In step (3), the metal organic framework is a copper-based metal organic framework, preferably MFM-170.

12. The method according to claim 11, characterized in that The method further comprises preparing the copper-based metal organic framework according to the following steps: Dissolving 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) and copper salt in an aqueous solution containing N,N-dimethylformamide, adding concentrated nitric acid for acidification, and then heating the solution; Preferably, the molar ratio of the 4',4'''-(pyridine-3,5-diyl)bis(([1,1'-biphenyl]-3,5-dicarboxylic acid)) to the copper salt is 1:1.5-2 in terms of Cu.

13. The method according to claim 5, characterized in that In step (4), the mass volume ratio of the modified activated carbon to the polyvinyl formal solution is 1 g: 2.5-4.5 mL; Preferably, the concentration of the polyvinyl formal solution is 3-8wt%.

14. The method according to claim 5 or 13, characterized in that: In step (4), the process of molding the slurry by phase inversion method includes: The slurry is dripped into water drop by drop to solidify into micro beads, and then the formed micro beads are separated from the solid and liquid and dried.

15. A modified activated carbon material prepared by the method according to any one of claims 5 to 14.

16. Use of the modified activated carbon material according to any one of claims 1 to 4 and 15 in the process of adsorbing sulfur dioxide.

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