MOF (Metal Organic Framework) material capable of efficiently adsorbing, catalyzing and decomposing gaseous pollutants and preparation method of MOF material

Abstract

The invention discloses an MOF material capable of efficiently adsorbing, catalyzing and decomposing gaseous pollutants and a preparation method of the MOF material, and relates to the technical field of air purification materials. The MOF material capable of efficiently adsorbing, catalyzing and decomposing the gaseous pollutants comprises the following raw materials in parts by weight: 8-15 parts of modified terephthalic acid, 5-10 parts of modified chitosan, 10-20 parts of zinc nitrate, 5-10 parts of cobalt nitrate hexahydrate, 6-12 parts of trimesic acid and 80-150 parts of N, N-dimethylformamide. The invention discloses an environment-friendly water-based fuel which comprises the following components: N, N-dimethylformamide, 50-100 parts of absolute ethyl alcohol, 2-5 parts of glacial acetic acid, 30-60 parts of deionized water, 3-8 parts of activated carbon powder, 2-6 parts of active manganese powder and 5-15 parts of a sodium hydroxide solution. The MOF material can accurately adsorb polar gaseous pollutants such as formaldehyde, meets the multi-component purification requirement, can achieve whole-process purification of adsorption-fixation-conversion-decomposition, has excellent moisture resistance and cycling stability, is matched with an air purification filter element, can be widely applied to indoor scenes such as families and offices, and is high in industrialization and practicability.

Description

Technical Field

[0001] This invention relates to the field of air purification materials technology, specifically to a MOF material that can efficiently adsorb and catalytically decompose gaseous pollutants and its preparation method. Background Technology

[0002] Formaldehyde, methanethiol, ammonia, acetic acid, benzene compounds (such as benzene, toluene, and xylene), and TVOCs (total volatile organic compounds) are the main gaseous pollutants in indoor environments, with wide-ranging sources and significant hazards. Formaldehyde mainly originates from furniture boards, paints, and adhesives, with a release period of 3-15 years. Long-term exposure can cause respiratory diseases, allergic reactions, and even cancer. Methanethiol and ammonia often come from pet odors and household waste, and have a strong, pungent smell. Acetic acid is mainly produced during kitchen cooking and from the volatilization of building materials, and can easily cause eye and respiratory discomfort. Benzene compounds and TVOCs are commonly found in paints, cleaning agents, and decorative materials, and have chronic toxicity and carcinogenic risks. Therefore, the simultaneous and efficient purification of multiple indoor gaseous pollutants has become a core requirement in the field of air purification.

[0003] Currently, gaseous pollutant purification technologies mainly include physical adsorption, chemical decomposition, and photocatalytic oxidation. Physical adsorption commonly uses activated carbon and conventional MOF materials, but these methods have significant drawbacks: activated carbon has a limited adsorption capacity for polar pollutants (such as formaldehyde and acetic acid), typically below 50 mg / g, and is easily saturated and difficult to regenerate, potentially releasing pollutants and causing secondary pollution after saturation; while conventional MOF materials have a large specific surface area, they have poor selectivity for specific pollutants, and their crystal structure easily collapses in humid environments, resulting in performance degradation exceeding 40%. Chemical decomposition relies on oxidants or catalysts, requiring harsh reaction conditions such as high temperature and high pressure, and easily generates secondary pollutants such as NOx and CO. Photocatalytic oxidation requires ultraviolet or visible light irradiation and completely fails in the absence of light at night or in enclosed spaces such as wardrobes and drawers, limiting its practical application.

[0004] MOF materials possess natural advantages in gas adsorption and catalysis due to their ultra-large specific surface area, tunable pore structure, and abundant active sites. However, existing MOF materials suffer from three core problems: first, poor selectivity, failing to achieve precise adsorption of polar pollutants such as formaldehyde and methanethiol; second, weak stability, with active sites easily occupied by water molecules in high humidity environments, leading to ineffectiveness after less than 10 cycles; and third, vague application scenarios, failing to meet the actual needs of air purification devices / filters, making direct commercialization difficult. To address these shortcomings, developing a MOF material that combines high adsorption capacity, high catalytic efficiency, strong selectivity, and stability, and can be directly applied to air purification filters, is of great significance for promoting the upgrading of indoor air purification technology. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants, and its preparation method, thus solving the problems of low adsorption capacity, poor selectivity, weak stability, and unclear application scenarios of traditional materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants comprises the following raw materials in parts by weight: 8-15 parts modified terephthalic acid, 5-10 parts modified chitosan, 10-20 parts zinc nitrate, 5-10 parts cobalt nitrate hexahydrate, 6-12 parts trimesic acid, 80-150 parts N,N-dimethylformamide, 50-100 parts anhydrous ethanol, 2-5 parts glacial acetic acid, 30-60 parts deionized water, 3-8 parts activated carbon powder, 2-6 parts activated manganese powder, and 5-15 parts sodium hydroxide solution.

[0007] Furthermore, the sodium hydroxide solution has a mass fraction of 15%; the activated carbon powder has a particle size of 100-300 mesh and a specific surface area ≥800 m². 2 / g, which can increase the contact area with formaldehyde molecules, significantly improving the adsorption rate and capacity of the material for formaldehyde; the active manganese powder has a particle size of 200-400 mesh and a specific surface area ≥150m². 2 / g, with a manganese dioxide mass fraction ≥85%, it can rapidly oxidize pollutants such as formaldehyde into carbon dioxide and water at room temperature without clogging MOF pores.

[0008] Furthermore, the modified terephthalic acid is prepared using the following specific steps: A1. First, terephthalic acid was ground in a mortar for 30 minutes and passed through a 200-mesh sieve. Then, it was mixed with anhydrous ethanol and malonic acid, and trifluoromethanesulfonic acid was added as a catalyst. The mixture was stirred at 80℃ and 500 r / min for 4 hours. After the reaction, the mixture was slowly poured into ice water while stirring. A precipitate was formed and filtered using a Buchner funnel. The precipitate was washed three times with ethanol, and filtered after each wash. The washed precipitate was placed in a vacuum drying oven and dried at 60℃ for 8 hours to obtain the first modified terephthalic acid. Grinding and sieving can reduce the particle size of terephthalic acid and improve the reaction contact efficiency. The introduction of malonic acid can increase the active functional groups, and trifluoromethanesulfonic acid can efficiently catalyze the reaction. Precipitation in ice water and washing with ethanol can improve the purity of the product. A1 introduces carboxyl active sites through malonic acid, which can enhance the adsorption affinity for polar pollutants. A2. Prepare an ethanol solution containing pyridine and formaldehyde, and sonicate it in an ultrasonic cleaner for 15 min. Take the first modified terephthalic acid and add it to the mixture. After mixing, react at 50℃ and 400 r / min for 6 h. During the reaction, maintain reflux and pass 20℃ circulating water through the condenser. After the reaction is complete, transfer the reaction solution to a rotary evaporator and distill it at 60℃ and a vacuum of 0.08 MPa to remove ethanol and pyridine until no liquid is distilled off, obtaining the second modified terephthalic acid. Ultrasonic treatment promotes thorough mixing of pyridine and formaldehyde, enhancing reaction uniformity. Reflux reduces raw material volatilization loss and improves raw material utilization. A2 introduces basic sites through pyridine-formaldehyde modification, enhancing the selective adsorption of acidic pollutants. A3. The second modified terephthalic acid was mixed with cobalt acetylacetonate, and N,N-dimethylformamide was added as a solvent. The reaction was carried out under a nitrogen atmosphere with a nitrogen flow rate controlled at 20 mL / min. Nitrogen was first purged for 30 min to remove air, and then the reaction was carried out at 100℃ and 600 r / min for 5 h. After the reaction was completed, the heating device was turned off, and nitrogen was continued to be purged until it cooled to room temperature. The reaction solution was filtered through a sintered glass funnel and washed three times with N,N-dimethylformamide. After each wash, the mixture was allowed to stand for 5 min before filtration. This allowed any unreacted raw materials remaining on the surface to fully dissolve in the washing solution, preventing impurities from being trapped with the solid product. The product was placed in a forced-air drying oven and dried at 70℃ for 6 h to obtain modified terephthalic acid. The addition of cobalt acetylacetonate can introduce metal coordination sites, enhancing the binding ability with metal ions. A3 introduces cobalt coordination sites through cobalt acetylacetonate, providing active centers for the catalytic decomposition of pollutants.

[0009] Furthermore, the ratio of terephthalic acid, anhydrous ethanol, malonic acid, trifluoromethanesulfonic acid, and ice water in A1 is 10g:50mL:2g:0.5g:200mL.

[0010] Furthermore, the ratio of pyridine, formaldehyde, ethanol, and first-modified terephthalic acid in A2 is 2.4g:1.6g:30mL:8g.

[0011] Furthermore, the ratio of the second modified terephthalic acid, cobalt acetylacetonate, and N,N-dimethylformamide in A3 is 6g:0.75g:40mL.

[0012] Furthermore, the modified chitosan is prepared using the following specific steps: B1. Soaking powdered chitosan in deionized water for 2 hours allows it to swell fully, facilitating subsequent dissolution. After draining, dissolve it in a 3% (w / w) acetic acid solution, stirring until completely dissolved. Then add succinic anhydride and triethylamine, and stir at 40℃ and 300 rpm for 3 hours. During the reaction, monitor the pH of the solution in real time with a pH meter, maintaining it between 6 and 7. This pH range ensures efficient acylation of the amino groups in succinic anhydride with chitosan, while avoiding excessive acidity leading to chitosan degradation or excessive alkalinity causing the succinic anhydride to decompose. Solution: After the reaction, the pH was adjusted to 7 with 1 mol / L sodium hydroxide solution to completely terminate the acylation reaction and avoid over-reaction. While adding the solution, stirring was performed to precipitate the mixture. The precipitate was then separated by centrifugation at 3000 r / min. The supernatant was discarded, and the precipitate was washed three times with deionized water, centrifuged for 5 min after each wash. The precipitate was then placed in a vacuum drying oven and dried at 60℃ for 10 h to obtain the first modified chitosan. Succinic anhydride introduced carboxyl groups, and triethylamine maintained pH stability to promote the reaction. B1 introduced carboxyl groups through succinic anhydride acylation, enhancing the binding force with MOF materials. B2. Take the first modified chitosan and add it to a deionized aqueous solution containing epichlorohydrin and imidazole at 40℃. After mixing, react at 60℃ and 450r / min for 4h. Stir the mixture during the reaction. After the reaction is complete, transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000-14000Da and dialyze it with deionized water for 72h, changing the deionized water every 6h. After dialysis, transfer the solution in the dialysis bag to a freeze dryer and freeze dry it at -50℃ and 0.09MPa for 24h to obtain the second modified chitosan. B2 improves the structural stability by crosslinking with epichlorohydrin and avoids dissolution in a humid environment. B3. The second-modified chitosan was mixed with 3-aminopropyltriethoxysilane, and methanol at 50°C was added as a solvent. The mixture was refluxed at 70°C and 500 rpm for 5 hours. After the reaction was completed, the reaction solution was transferred to a distillation flask, and methanol was removed by atmospheric distillation at a rate of 1 drop per second. This ensured full recovery of methanol, reduced production costs, and avoided damage to the product structure due to excessively rapid distillation. The distilled methanol was collected for recycling. After distillation, the modified chitosan was obtained. B3 introduces an amino group through 3-aminopropyltriethoxysilane, which can react with formaldehyde via a Schiff base reaction to achieve complete degradation.

[0013] Furthermore, the ratio of chitosan, deionized water, acetic acid solution, succinic anhydride, and triethylamine in B1 is 10g:50mL:500mL:5g:2g.

[0014] Furthermore, the ratio of the first modified chitosan, epichlorohydrin, imidazole, and deionized water in B2 is 8g:2.4g:0.8g:80mL.

[0015] Furthermore, the ratio of the second modified chitosan, 3-aminopropyltriethoxysilane, and methanol in B3 is 6g:2.4g:30mL.

[0016] A method for preparing a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants, specifically comprising the following steps: S1. Dissolve zinc nitrate and cobalt nitrate hexahydrate separately in N,N-dimethylformamide and stir until homogeneous to form a metal salt solution; separately dissolve modified terephthalic acid and trimesic acid in N,N-dimethylformamide at 60℃ to obtain an organic ligand solution; slowly add the metal salt solution dropwise to the organic ligand solution, and simultaneously add glacial acetic acid, mixing thoroughly under stirring to carry out the coordination reaction, with the temperature controlled at 60-70℃; after the addition is complete, slowly add sodium hydroxide solution to adjust the pH value to between 6.5 and 7.5 to obtain a mixed solution; S2. Transfer the mixed solution to the reaction vessel, seal it, and place it in an oven. React at 120-150℃ for 12-24 hours to form stable zinc-cobalt bimetallic MOF primary crystals. After the reaction is completed, allow the reaction vessel to cool naturally to room temperature. Natural cooling can avoid damage to the crystal structure due to sudden temperature changes. Then, take out the reaction product and separate it by centrifugation to obtain the solid precipitate, which is the initially synthesized MOF material. S3. Wash the precipitate four times with anhydrous ethanol, and collect the solid by centrifugation after each wash. Put the activated carbon powder, activated manganese powder and the washed MOF material into a mortar and grind for 15-30 minutes to ensure that the activated carbon and activated manganese are evenly dispersed in the MOF material. This ensures that the activated carbon powder and MOF material are evenly mixed, and avoids over-grinding that will damage the crystal structure of the MOF material. S4. Dissolve the modified chitosan in deionized water, add the MOF material mixed with activated carbon powder to the modified chitosan solution, heat to 40-50℃, control the stirring speed at 300-500r / min, and stir for 2-4h to obtain the composite material. S5. The composite material is centrifuged again to collect the solid product. The product is washed four times with deionized water and anhydrous ethanol. The washed product is placed in an oven and dried at 60-80℃ to constant weight to obtain MOF material that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0017] Furthermore, in S1, the metal salt solution is added to the organic ligand solution at a rate of 1-2 drops / second to avoid excessively high local concentrations of metal ions, prevent the formation of irregular crystal structures, and ensure that the coordination reaction proceeds in an orderly manner. During the addition process, the stirring speed is maintained at 400-600 r / min.

[0018] Furthermore, in S1, both zinc nitrate and cobalt nitrate hexahydrate are vacuum dried at 100°C for 4 hours before use, which can effectively remove the water of crystallization and adsorbed water in zinc nitrate and cobalt nitrate hexahydrate, avoid the interference of moisture on the coordination reaction, and ensure the stability of the reaction and the quality of the product; after drying, they are sealed and stored in a desiccator to avoid moisture absorption affecting the efficiency of the coordination reaction.

[0019] This invention provides a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants and its preparation method, which has the following beneficial effects: 1. This MOF material, through scientific raw material formulation and stepwise modification process, possesses excellent adsorption capacity. Modified terephthalic acid undergoes three modifications to introduce carboxyl groups, basicity, and metal coordination sites, combined with a particle size of 100-300 mesh and a specific surface area ≥800 m². 2 This activated carbon powder, at a concentration of / g, significantly enhances the adsorption affinity for polar gaseous pollutants such as formaldehyde and methanethiol. Furthermore, the pore structure synergistically constructed by trimesic acid and metal salts can accommodate a variety of pollutant molecular sizes. Compared to the limited adsorption capacity of traditional activated carbon for polar pollutants and the poor selectivity of conventional MOFs, this material can precisely adsorb major gaseous pollutants in indoor environments, meeting the needs of multi-component purification.

[0020] 2. The material constructs a complete purification chain through the synergistic effect of multiple components. First, the composite structure of modified terephthalic acid and activated carbon efficiently adsorbs gaseous pollutants. Next, the amino sites introduced by modified chitosan form stable chemical bonds with pollutant molecules, fixing them to the material surface and preventing secondary pollution caused by desorption after adsorption. Subsequently, the active centers of the zinc-cobalt bimetallic MOF promote the transformation of pollutant molecular structures, breaking harmful chemical bonds. Finally, activated manganese powder accelerates the oxidation reaction at room temperature, completely decomposing the intermediate products after transformation into carbon dioxide and water. The entire process does not require high temperature, high pressure, or light assistance, solving the problem that traditional technologies can only perform single adsorption or decomposition and are prone to secondary pollution, achieving harmless purification throughout the entire process.

[0021] 3. Multiple structural optimization designs endow the material with excellent stability. Modified chitosan undergoes epichlorohydrin cross-linking treatment, effectively enhancing its resistance to dissolution and preventing structural damage in humid environments. The zinc-cobalt bimetallic MOF crystal structure itself possesses high stability. Combined with processes such as centrifugation, multiple washing, and vacuum drying during preparation, impurities and structural defects are reduced. Furthermore, the material is less prone to loss of function due to adsorption saturation during use, and exhibits high performance retention after regeneration. This solves the pain points of traditional adsorption materials, such as easy saturation, difficulty in regeneration, and deactivation under high humidity, significantly extending the material's service life.

[0022] 4. The material's preparation process is standardized and parameters are clearly defined. From raw material pretreatment to the coordination reaction and composite modification of metal salt solution and organic ligand solution, and finally to drying and molding, the temperature, rotation speed, time, and other parameters of each step can be precisely controlled, possessing the potential for large-scale production. Simultaneously, the material is clearly compatible with air purification devices / filters, and can be integrated into existing purification equipment without additional processing. It can be directly applied to indoor scenarios such as homes and offices, and is especially suitable for enclosed spaces such as wardrobes and drawers, achieving efficient transformation from technology research and development to practical application. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: Preparation of MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants. The specific preparation steps are as follows: S1. Dissolve 10 parts zinc nitrate and 5 parts cobalt nitrate hexahydrate in 40 parts N,N-dimethylformamide and stir until homogeneous to form a metal salt solution. Separately, dissolve 8 parts modified terephthalic acid and 6 parts trimesic acid in 40 parts N,N-dimethylformamide at 60℃ to obtain an organic ligand solution. Add the metal salt solution dropwise to the organic ligand solution at a rate of 1 drop / second, and simultaneously add 2 parts glacial acetic acid. Mix thoroughly under stirring at 400 r / min to carry out the coordination reaction, and control the temperature at 60℃. After the addition is complete, slowly add 5 parts sodium hydroxide solution to adjust the pH value to 6.5 to obtain a mixed solution. S2. Transfer the mixed solution to the reaction vessel, seal it, and place it in an oven. React at 120°C for 12 hours to form the primary crystal structure of the MOF material. After the reaction is completed, allow the reaction vessel to cool naturally to room temperature, remove the reaction product, and obtain the solid precipitate by centrifugation, which is the initially synthesized MOF material. S3. Wash the precipitate four times with 50 parts of anhydrous ethanol. After each washing, centrifuge to collect the solid. Take 3 parts of activated carbon powder, 2 parts of activated manganese powder and put them into a mortar together with the washed MOF material. Grind for 15 minutes to ensure that the activated carbon and activated manganese are evenly dispersed in the MOF material. S4. Dissolve 5 parts of modified chitosan in 30 parts of deionized water, add the MOF material mixed with activated carbon powder to the modified chitosan solution, heat to 40℃, control the stirring speed at 300r / min, and stir for 2h to obtain the composite material. S5. The composite material is centrifuged again to collect the solid product. The product is washed four times with deionized water and anhydrous ethanol. The washed product is placed in an oven and dried at 60°C to constant weight to obtain the MOF material that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0025] Example 2: Preparation of MOF materials capable of efficiently adsorbing and catalytically decomposing gaseous pollutants. The specific preparation steps are as follows: S1. Dissolve 20 parts of zinc nitrate and 10 parts of cobalt nitrate hexahydrate in 70 parts of N,N-dimethylformamide and stir until homogeneous to form a metal salt solution. Separately, dissolve 15 parts of modified terephthalic acid and 12 parts of trimesic acid in 80 parts of N,N-dimethylformamide at 60℃ to obtain an organic ligand solution. Add the metal salt solution dropwise to the organic ligand solution at a rate of 2 drops / second, and simultaneously add 5 parts of glacial acetic acid. Mix thoroughly under stirring at 600 r / min to carry out the coordination reaction, and control the temperature at 70℃. After the addition is complete, slowly add 15 parts of sodium hydroxide solution to adjust the pH value to 7.5 to obtain a mixed solution. S2. Transfer the mixed solution to the reaction vessel, seal it, and place it in an oven. React at 150°C for 24 hours to form the primary crystal structure of the MOF material. After the reaction is completed, allow the reaction vessel to cool naturally to room temperature, remove the reaction product, and obtain the solid precipitate by centrifugation, which is the initially synthesized MOF material. S3. Wash the precipitate four times with 100 parts of anhydrous ethanol. After each wash, centrifuge to collect the solid. Take 8 parts of activated carbon powder, 6 parts of activated manganese powder and put them into a mortar together with the washed MOF material. Grind for 30 minutes to ensure that the activated carbon and activated manganese are evenly dispersed in the MOF material. S4. Dissolve 10 parts of modified chitosan in 60 parts of deionized water, add the MOF material mixed with activated carbon powder to the modified chitosan solution, heat to 50℃, control the stirring speed at 500r / min, and stir for 4h to obtain the composite material. S5. The composite material is centrifuged again to collect the solid product. The product is washed four times with deionized water and anhydrous ethanol. The washed product is placed in an oven and dried at 80°C to constant weight to obtain MOF material that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0026] Example 3: Preparation of MOF materials capable of efficiently adsorbing and catalytically decomposing gaseous pollutants. The specific preparation steps are as follows: S1. Dissolve 15 parts zinc nitrate and 7 parts cobalt nitrate hexahydrate in 55 parts N,N-dimethylformamide and stir until homogeneous to form a metal salt solution. Separately, dissolve 11 parts modified terephthalic acid and 9 parts trimesic acid in 60 parts N,N-dimethylformamide at 60℃ to obtain an organic ligand solution. Add the metal salt solution dropwise to the organic ligand solution at a rate of 1 drop / second, and simultaneously add 3 parts glacial acetic acid. Mix thoroughly under stirring at 500 r / min to carry out the coordination reaction, and control the temperature at 65℃. After the addition is complete, slowly add 10 parts sodium hydroxide solution to adjust the pH value to 7.0 to obtain a mixed solution. S2. Transfer the mixed solution to the reaction vessel, seal it, and place it in an oven. React at 135°C for 18 hours to form the primary crystal structure of the MOF material. After the reaction is completed, allow the reaction vessel to cool naturally to room temperature, remove the reaction product, and obtain the solid precipitate by centrifugation, which is the initially synthesized MOF material. S3. Wash the precipitate four times with 75 parts of anhydrous ethanol. After each washing, centrifuge to collect the solid. Take 5 parts of activated carbon powder, 4 parts of activated manganese powder and put them into a mortar together with the washed MOF material. Grind for 22 minutes to ensure that the activated carbon and activated manganese are evenly dispersed in the MOF material. S4. Dissolve 7 parts of modified chitosan in 45 parts of deionized water, add the MOF material mixed with activated carbon powder to the modified chitosan solution, heat to 45℃, control the stirring speed at 400r / min, and stir for 3h to obtain the composite material. S5. The composite material is centrifuged again to collect the solid product. The product is washed four times with deionized water and anhydrous ethanol. The washed product is placed in an oven and dried at 70°C to constant weight to obtain the MOF material that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0027] Example 4: Preparation of modified terephthalic acid. The specific preparation steps are as follows: A1. First, grind 10g of terephthalic acid in a mortar for 30min and pass it through a 200-mesh sieve. Then, mix it with 50mL of anhydrous ethanol and 2g of malonic acid, add 0.5g of trifluoromethanesulfonic acid as a catalyst, and stir the mixture at 80℃ and 500r / min for 4h. After the reaction is complete, slowly pour the mixture into 200mL of ice water while stirring. A precipitate will form. Filter the precipitate with a Buchner funnel and wash it three times with ethanol. Filter the precipitate after each wash. Place the washed precipitate in a vacuum drying oven and dry it at 60℃ for 8h to obtain the first modified terephthalic acid. A2. Prepare a 30 mL ethanol solution containing 2.4 g pyridine and 1.6 g formaldehyde, and sonicate it in an ultrasonic cleaner for 15 min. Take 8 g of the first modified terephthalic acid and add it to the mixture. After mixing, react at 50 °C and 400 r / min for 6 h. During the reaction, keep the reflux condenser running and pass 20 °C circulating water through the condenser. After the reaction is completed, transfer the reaction solution to a rotary evaporator and distill it at 60 °C and 0.08 MPa to remove ethanol and pyridine until no liquid is distilled off, to obtain the second modified terephthalic acid. A3. Mix 6g of second-modified terephthalic acid with 0.75g of cobalt acetylacetonate, add 40mL of N,N-dimethylformamide as solvent, and react under a nitrogen atmosphere with a nitrogen flow rate of 20mL / min. First, purge with nitrogen for 30min to remove air, then react at 100℃ and 600r / min for 5h. After the reaction is complete, turn off the heating device and continue to purge with nitrogen until it cools to room temperature. Filter the reaction solution with a sintered glass funnel and wash it three times with N,N-dimethylformamide. After each wash, let it stand for 5min and then filter again. Place the product in a forced-air drying oven and dry at 70℃ for 6h to obtain modified terephthalic acid.

[0028] Example 5: Preparation of modified chitosan. The specific preparation steps are as follows: B1. Soak 10g of powdered chitosan in 50mL of deionized water for 2 hours and drain. Then dissolve it in 500mL of 3% acetic acid solution and stir until completely dissolved. Add 5g of succinic anhydride and 2g of triethylamine and stir at 40℃ and 300r / min for 3 hours. During the reaction, monitor the pH value of the solution in real time with a pH meter and keep it between 6 and 7. After the reaction, adjust the pH to 7 with 1mol / L sodium hydroxide solution while stirring. The precipitate will precipitate and be separated by centrifugation at 3000r / min. After discarding the supernatant, wash the precipitate three times with deionized water. Centrifuge for 5 minutes after each wash. Place the precipitate in a vacuum drying oven and dry at 60℃ for 10 hours to obtain the first modified chitosan. B2. Take 8g of the first-modified chitosan and add it to 80mL of deionized water containing 2.4g of epichlorohydrin and 0.8g of imidazole at 40℃. After mixing, react at 60℃ and 450r / min for 4h. Stir with a stirrer during the reaction. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cutoff of 8000-14000Da and dialyze with deionized water for 72h. Change the deionized water every 6h. After the dialysis is completed, transfer the solution in the dialysis bag to a freeze dryer and freeze dry at -50℃ and 0.09MPa for 24h to obtain the second-modified chitosan. B3. Mix 6g of the second modified chitosan with 2.4g of 3-aminopropyltriethoxysilane, add 30mL of methanol at 50℃ as solvent, and reflux at 70℃ and 500r / min for 5h. After the reaction is complete, transfer the reaction solution to a distillation flask and remove methanol by atmospheric distillation at a rate of 1 drop per second. Collect the distilled methanol for recycling. After distillation, the modified chitosan is obtained.

[0029] Comparative Example 1: A MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants was prepared. The specific preparation steps are as follows: The remaining steps remain the same, except that the modified terephthalic acid in Example 3 is replaced with untreated terephthalic acid to prepare MOF materials that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0030] Comparative Example 2: A MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants was prepared. The specific preparation steps are as follows: The remaining steps remain unchanged, except that the modified chitosan in Example 3 is replaced with untreated chitosan to prepare MOF materials that can efficiently adsorb and catalytically decompose gaseous pollutants.

[0031] Performance testing

[0032] The performance test results show that, under the conditions of 25℃, corresponding initial concentration, and 24h adsorption / degradation, the adsorption and catalytic performance of Examples 1-3 are comprehensively superior to those of Comparative Example 1 (using unmodified terephthalic acid) and Comparative Example 2 (using unmodified chitosan). In terms of adsorption capacity, Example 3 adsorbs 65-95 mg / g of key gaseous pollutants such as formaldehyde and methanethiol, far exceeding the 38-52 mg / g of Comparative Example 1. Regarding catalytic degradation efficiency, Example 3 achieves a formaldehyde degradation rate of 98% and a methanethiol degradation rate of 95%, while Comparative Example 1 only achieves 72% and 68%, respectively. In terms of adsorption selectivity, Example 3 achieved a polar / non-polar gas adsorption ratio of 1.46, precisely targeting harmful polar pollutants. In terms of stability, Example 3 retained 90% of the formaldehyde adsorption capacity under high humidity (80% RH) conditions, and still maintained 88% after 5 cycles, significantly better than Comparative Example 2's 52% and 58%. In terms of decomposition capacity, Example 3 achieved a formaldehyde decomposition amount of 93.1 mg / g, solving the problems of adsorption saturation and high humidity deactivation of traditional materials. In contrast, the comparative example, due to the lack of modification of raw materials, showed significant performance degradation and the risk of trace pollutant residues.

[0033] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants, characterized in that: The modified terephthalic acid, the specific preparation steps are as follows: 2.The MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution is 15%; the particle size of the activated carbon powder is 100-300 mesh, and the specific surface area is greater than or equal to 800 m 2 / g; the particle size of the activated manganese powder is 200-400 mesh, and the specific surface area is greater than or equal to 150 m 2 / g, and the mass fraction of manganese dioxide is greater than or equal to 85%. 3.The MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants according to claim 1, characterized in that: A1, first, terephthalic acid is placed in a mortar and ground for 30 min, and then it is mixed with anhydrous ethanol, malonic acid, and trifluoromethanesulfonic acid is added as a catalyst, and stirred at 80 DEG C, 500 r / min for 4 h, after the reaction, the mixture is slowly poured into ice water, and stirred, the precipitate is filtered with a Buchner funnel, and washed with ethanol for 3 times, after each washing, the precipitate is placed in a vacuum drying oven, dried at 60 DEG C for 8 h, and the first modified terephthalic acid is obtained; A2, an ethanol solution containing pyridine and formaldehyde is prepared, and ultrasonic cleaning is carried out in an ultrasonic cleaner for 15 min, the first modified terephthalic acid is taken and added to the mixed solution, and after mixing, it is reacted at 50 DEG C, 400 r / min for 6 h, and during the reaction, the condenser is kept at 20 DEG C, after the reaction, the reaction liquid is transferred to a rotary evaporator, and ethanol and pyridine are distilled off at 60 DEG C, 0.08 MPa, until no liquid is distilled off, and the second modified terephthalic acid is obtained; A3, the second modified terephthalic acid is mixed with cobalt acetylacetone, and N,N-dimethylformamide is added as a solvent, and the reaction is carried out under a nitrogen atmosphere, the nitrogen flow is controlled at 20 mL / min, nitrogen is passed for 30 min to remove air, and then the reaction is carried out at 100 DEG C, 600 r / min for 5 h, after the reaction, the heating device is turned off, and nitrogen is continued to be passed until it is cooled to room temperature, the reaction liquid is filtered with a sand core funnel, and washed with N,N-dimethylformamide for 3 times, after each washing, it is placed for 5 min and then filtered, and the product is placed in a blast drying oven, dried at 70 DEG C for 6 h, and the modified terephthalic acid is obtained. The amount ratio of terephthalic acid, anhydrous ethanol, malonic acid, trifluoromethanesulfonic acid and ice water in A1 is 10 g: 50 mL: 2 g: 0.5 g: 200 mL; 4. The MOF material of claim 3, wherein: The amount ratio of pyridine, formaldehyde, ethanol and the first modified terephthalic acid in A2 is 2.4 g: 1.6 g: 30 mL: 8 g; The amount ratio of the second modified terephthalic acid, cobalt acetylacetone and N,N-dimethylformamide in A3 is 6 g: 0.75 g: 40 mL. The modified chitosan, the specific preparation steps are as follows:

5. The MOF material of claim 1, wherein: ​ B1, the powdered chitosan is soaked in deionized water for 2h, then it is dissolved in 3% acetic acid solution, stirred until completely dissolved, then succinic anhydride and triethylamine are added, stirred at 40℃, 300r / min for 3h, the pH value of the solution is monitored in real time during the reaction by pH meter, and the pH value is maintained between 6-7, after the reaction, the pH value is adjusted to 7 with 1mol / L sodium hydroxide solution, and the precipitate is separated by centrifugation at 3000r / min, the supernatant is discarded, and the precipitate is washed with deionized water for 3 times, each time after washing, centrifugation for 5min, the precipitate is placed in a vacuum drying oven, dried at 60℃ for 10h, to obtain the first modified chitosan; B2, the first modified chitosan is taken and added to a deionized water solution containing epichlorohydrin and imidazole at 40℃, mixed and reacted at 60℃, 450r / min for 4h, the reaction process is stirred by stirring paddle, after the reaction is completed, the reaction solution is transferred to a dialysis bag with a molecular weight cutoff of 8000-14000Da, dialyzed with deionized water for 72h, and the deionized water is replaced every 6h, after dialysis is completed, the solution in the dialysis bag is transferred to a freeze dryer, and freeze-dried at-50℃, vacuum degree 0.09MPa for 24h, to obtain the second modified chitosan; B3, the second modified chitosan is mixed with 3-aminopropyl triethoxysilane, and methanol with a temperature of 50℃ is added as a solvent, refluxed at 70℃, 500r / min for 5h, after the reaction is completed, the reaction solution is transferred to a distillation flask, and the methanol is removed by atmospheric distillation, the distillation speed is controlled at 1 drop per second, and the distilled methanol is collected for recycling, after the distillation is completed, the modified chitosan is obtained.

6. The MOF material of claim 5, wherein: The amount ratio of chitosan, deionized water, acetic acid solution, succinic anhydride, triethylamine in B1 is 10g:50mL:500mL:5g:2g; The amount ratio of the first modified chitosan, epichlorohydrin, imidazole, deionized water in B2 is 8g:2.4g:0.8g:80mL; The amount ratio of the second modified chitosan, 3-aminopropyl triethoxysilane, methanol in B3 is 6g:2.4g:30mL.

7. A method for preparing a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants, characterized in that: Specifically comprising the following steps: S1, zinc nitrate and cobalt nitrate hexahydrate are respectively dissolved in N,N-dimethylformamide to form a metal salt solution; another modified terephthalic acid and trimesic acid are dissolved in 60℃ N,N-dimethylformamide to obtain an organic ligand solution; the metal salt solution is slowly added to the organic ligand solution, and glacial acetic acid is added at the same time, and the mixture is uniformly mixed under stirring to carry out coordination reaction, and the temperature is controlled at 60-70℃; after the addition is completed, sodium hydroxide solution is slowly added to adjust the pH value to 6.5-7.5, to obtain a mixed solution; S2, transfer the mixed solution to a reaction kettle, after sealing, put it into an oven, react at 120-150℃ for 12-24h to form the primary crystal structure of MOF material; after the reaction is completed, the reaction kettle is naturally cooled to room temperature, the reaction product is taken out, and the solid precipitate, i.e. the preliminary synthesized MOF material, is obtained by centrifugal separation; S3, wash the precipitate with anhydrous ethanol for 4 times, and collect the solid after each washing by centrifugal separation; take activated carbon powder, activated manganese powder and the MOF material after washing into a mortar, and grind for 15-30min to ensure that the activated carbon and activated manganese are uniformly dispersed in the MOF material; S4, dissolve the modified chitosan in deionized water, add the MOF material mixed with activated carbon powder into the modified chitosan solution, heat to 40-50℃, control the stirring speed at 300-500r / min, and stir for 2-4h to obtain a composite material; S5, centrifugally separate the composite material again, collect the solid product, wash the product with deionized water and anhydrous ethanol alternately for 4 times, and dry the washed product in an oven at 60-80℃ to constant weight to obtain a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants.

8. The method of claim 7, wherein the MOF material is capable of efficiently adsorbing and catalytically decomposing gaseous pollutants. The dropping speed of the metal salt solution in S1 into the organic ligand solution is 1-2 drops / s, and the stirring speed is maintained at 400-600r / min during the dropping process.

9. The method for preparing a MOF material capable of efficiently adsorbing and catalytically decomposing gaseous pollutants according to claim 7, characterized in that: The zinc nitrate and cobalt nitrate hexahydrate in S1 are vacuum dried at 100℃ for 4h before use, and are sealed and stored in a desiccator after drying to avoid moisture absorption affecting the coordination reaction efficiency.

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