Preparation method and application of MOF material

Abstract

The invention provides a preparation method and application of an MOF material, and relates to the technical field of materials. The preparation method of the MOF material provided by the invention comprises the following steps: mixing a metal salt and an organic ligand for preparing the MOF material in water to obtain a solution; adding a pH regulator to regulate the pH of the solution to 2-5 for reaction, and drying a reaction product after the reaction is finished to obtain an MOF material; wherein the reaction temperature is 110-230 DEG C, and the drying mode is supercritical CO2 drying or freeze drying. According to the preparation method, a water-based process is adopted, and precursor preparation, reaction conditions and post-treatment processes are optimized, so that the environmental influence and the production cost are remarkably reduced, and meanwhile, the high yield and the product quality stability are kept. The prepared MOF material shows excellent water adsorption performance in a low-humidity environment, and is suitable for water catching in arid regions.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a method for preparing MOF materials and their applications. Background Technology

[0002] In recent years, metal-organic frameworks (MOFs) have become a research hotspot in the field of water capture applications due to their high porosity, excellent adsorption performance, and diverse chemical structures. MOFs, through their porous structure, can effectively adsorb water vapor from the air and release moisture under specific conditions, offering potential for solving water scarcity problems. Studies have shown that MOF-based devices can capture water from the air in low-humidity environments (such as 20% relative humidity), making them particularly suitable for desert and semi-arid regions.

[0003] However, traditional MOF synthesis methods have significant limitations. These methods typically rely on toxic solvents (such as N,N-dimethylformamide (DMF) and hydrofluoric acid (HF)) and high-temperature, high-pressure reaction conditions. N,N-dimethylformamide (DMF) is highly toxic (oral LD50 in rats is 5 g / kg) and has a persistent degradation rate (half-life >100 days), leading to high wastewater treatment costs. Hydrofluoric acid (HF) is highly corrosive, posing a threat to equipment and operator safety. High-temperature, high-pressure conditions (such as 250°C and 40 bar) increase energy consumption by 30%-40% and raise equipment maintenance costs. Therefore, traditional MOF synthesis methods not only impose a significant burden on the environment but also increase production costs, limiting their application in industrial production.

[0004] To overcome the above problems, there is an urgent need to develop an environmentally friendly, cost-effective and scalable method for synthesizing MOFs.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a method for preparing MOF materials to solve the aforementioned technical problems.

[0007] The second objective of this invention is to provide the application of the MOF-801 material prepared by the above-described method in atmospheric water collection.

[0008] To achieve the above objectives, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing MOF materials, comprising the following steps: The metal salt and organic ligand used for MOF material preparation were mixed in water to obtain a solution; The pH of the solution was adjusted to 2-5 by adding a pH adjuster to carry out the reaction. After the reaction was completed, the reaction product was dried to obtain the MOF material. The reaction temperature is 110–230°C, the drying method is supercritical CO2 drying or freeze drying, and the MOF material includes MOF-303, MOF-801, UiO-66 or MIL-101.

[0009] As a further technical solution, the metal salt used to prepare the MOF-303 is Al(OH)3, and the organic ligand is pyrazole-3,5-dicarboxylic acid (PZDC). The molar ratio of the metal salt to the organic ligand of the MOF-303 is (0.8–1.2):1; The reaction temperature of the metal salt and organic ligand of MOF-303 is 110–130 °C.

[0010] As a further technical solution, the metal salt used to prepare the MOF-801 is ZrCl4, and the organic ligand is fumaric acid; The molar ratio of the metal salt to the organic ligand of the MOF-801 is 1:(1.5 to 1.9); The reaction temperature of the metal salt and organic ligand of MOF-801 is 120–170 °C.

[0011] As a further technical solution, the metal salt used to prepare the UiO-66 is ZrCl4, and the organic ligand is terephthalic acid (H2BDC); The molar ratio of the metal salt to the organic ligand of the UiO-66 is (0.9–1.1):1; The reaction temperature of the metal salt and organic ligand of UiO-66 is 110–130 °C.

[0012] As a further technical solution, the metal salt used to prepare the MIL-101 is chromium nitrate nonahydrate, and the organic ligand is terephthalic acid.

[0013] The molar ratio of the metal salt to the organic ligand in MIL-101 is (0.8–1.2):1; The reaction temperature of the metal salt and organic ligand of MIL-101 is 200–230 °C.

[0014] As a further technical solution, microwave-assisted heating is used to heat the solution to the reaction temperature.

[0015] As a further technical solution, the pH adjuster includes acetic acid, citric acid, or nitric acid.

[0016] As a further technical solution, the reaction process includes a step of solid-liquid separation to collect the reaction products and washing the reaction products after the reaction is completed. The solvents used for washing include water and ethanol.

[0017] As a further technical solution, the drying process also includes activating the reaction products.

[0018] Secondly, the present invention provides the application of the MOF-801 material prepared by the above preparation method in atmospheric water collection.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method provided by the present invention is universal. By fine-tuning the parameters, the method can be used for the synthesis of various MOFs.

[0020] (2) The preparation method provided by the present invention is green and environmentally friendly. By adopting a water-based process, the use of toxic solvents is avoided, thereby reducing environmental pollution and lowering the cost of waste liquid treatment.

[0021] (3) The preparation method provided by the present invention has good scalability, mild reaction conditions, and is suitable for large-scale reactor operation.

[0022] (4) The MOF material prepared by the preparation method provided by the present invention has smaller grains and larger specific surface area, and has excellent water-capturing performance. It can exhibit excellent water adsorption capacity under low humidity and is suitable for water-capturing applications.

[0023] (5) The preparation method provided by the present invention simplifies the post-processing process, reduces energy consumption and waste treatment costs, and improves the economic benefits of industrial production. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 The process flow of the preparation method of the present invention is as follows; Figure 2 SEM image of MOF-303; Figure 3 SEM images of MOF-801; Figure 4 SEM image of UiO-66; Figure 5 SEM image of MIL-101. Detailed Implementation

[0026] The embodiments and examples of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments and examples are for illustrative purposes only and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] In a first aspect, the present invention provides a method for preparing MOF materials, comprising the following steps: Metal salts and organic ligands for MOF material preparation are mixed in water to obtain a solution; a pH adjuster is added to adjust the pH of the solution to 2-5 for reaction; after the reaction is completed, the reaction product is dried to obtain the MOF material; wherein the reaction temperature is 110-230℃, and the drying method is supercritical CO2 drying or freeze drying; the MOF material includes MOF-303, MOF-801, UiO-66 or MIL-101.

[0028] The MOF material preparation method provided by this invention employs a water-based process. By optimizing precursor preparation, reaction conditions, and post-processing, it significantly reduces environmental impact and production costs (compared to traditional methods, reaction time can be shortened to 1 / 10-1 / 5, energy consumption reduced by 30%-50%, and waste treatment costs reduced by 90%), while maintaining high yield (80%-91%) and stable product quality. By precisely controlling the pH value between 2 and 5, the coordination environment of metal ions and organic ligands is optimized, improving the crystallinity and performance of the MOF. The prepared MOF material exhibits excellent water adsorption performance (water adsorption capacity up to 31.5 g / 100 g) in low humidity environments (e.g., relative humidity 20%-30%), making it particularly suitable for water capture applications in arid regions. This invention's preparation method has good environmental friendliness, scalability, and versatility, and is applicable to the preparation of various MOF materials such as MOF-303, MOF-801, UiO-66, and MIL-101.

[0029] In some alternative embodiments, the metal salt used to prepare the MOF-303 is Al(OH)3, and the organic ligand is pyrazole-3,5-dicarboxylic acid.

[0030] The molar ratio of the metal salt and organic ligand of the MOF-303 can be, for example, but not limited to, 0.8:1, 1:1 or 1.2:1, preferably 1:1.

[0031] The reaction temperature of the metal salt and organic ligand of MOF-303 can be, for example, but not limited to, 110°C, 120°C or 130°C, preferably 120°C.

[0032] In some alternative embodiments, the metal salt used to prepare the MOF-801 is ZrCl4, and the organic ligand is fumaric acid.

[0033] The molar ratio of the metal salt and organic ligand of the MOF-801 can be, for example, but not limited to, 1:1.5, 1:1.7 or 1:1.9, preferably 1:1.7.

[0034] The reaction temperature of the metal salt and organic ligand of MOF-801 can be, for example, but not limited to, 120°C, 150°C, 160°C or 170°C, preferably 160°C.

[0035] In some alternative embodiments, the metal salt used to prepare the UiO-66 is ZrCl4, and the organic ligand is terephthalic acid.

[0036] The molar ratio of the metal salt and organic ligand of the UiO-66 can be, for example, but not limited to, 0.9:1, 1:1 or 1.1:1, preferably 1:1.

[0037] The reaction temperature of the metal salt and organic ligand of the UiO-66 can be, for example, but not limited to, 110°C, 120°C or 130°C, preferably 120°C.

[0038] In some alternative embodiments, the metal salt used to prepare the MIL-101 is chromium nitrate nonahydrate, and the organic ligand is terephthalic acid.

[0039] The molar ratio of the metal salt and organic ligand of the MIL-101 can be, for example, but not limited to, 0.8:1, 1:1 or 1.2:1, preferably 1:1.

[0040] The reaction temperature of the metal salt and organic ligand of MIL-101 can be, for example, but not limited to, 200°C, 215°C or 230°C, preferably 218°C.

[0041] This invention does not impose specific limitations on the heating method; any heating method well known to those skilled in the art can be used. In some optional embodiments, microwave-assisted heating is used to heat the solution to the reaction temperature.

[0042] In some alternative embodiments, the power of the microwave-assisted heating can be, for example, but not limited to, 300W, 500W, or 800W, and the reaction time can be, for example, but not limited to, 60 minutes, 90 minutes, or 120 minutes. Microwave-assisted heating can significantly shorten the conventional heating time.

[0043] In some alternative embodiments, the pH adjuster includes, but is not limited to, acetic acid, citric acid, or nitric acid, or a pH adjuster well known to those skilled in the art.

[0044] In some optional embodiments, the reaction may further include a step of solid-liquid separation to collect the reaction products and washing the reaction products after the reaction is completed.

[0045] The solvents used for washing include water and ethanol.

[0046] In some alternative implementations, the solid-liquid separation method includes, but is not limited to, filtration and centrifugation, or other solid-liquid separation methods well known to those skilled in the art.

[0047] In some alternative embodiments, the washing method includes washing three times sequentially with deionized water and sustainably sourced ethanol (twice the amount of the initial reaction solution each time), collecting the ethanol and recovering it through distillation for reuse, thereby reducing waste emissions.

[0048] In some alternative embodiments, the conditions for supercritical CO2 drying include: 40-70°C, 13 MPa.

[0049] The freeze-drying is a sublimation drying process carried out at -20°C to -80°C.

[0050] Supercritical CO2 drying or freeze drying can effectively protect the structure of MOF materials.

[0051] In some alternative embodiments, the drying process further includes activation of the reaction products, such as gas flow activation using nitrogen or argon (50-100°C), to remove residual moisture or impurities under mild conditions, replacing traditional high-temperature vacuum activation.

[0052] In some alternative embodiments, the MOF material has a water adsorption capacity ≥30g / 100g at a relative humidity of 20%-30%.

[0053] The MOF material prepared by the method of this invention has good water-capturing properties.

[0054] Secondly, the present invention provides the application of the MOF-801 material prepared by the above preparation method in atmospheric water collection.

[0055] The MOF material prepared by this invention has good water-capturing properties and can be used for atmospheric water collection.

[0056] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0057] Example 1: Process flow of UiO-66 This embodiment provides a reaction pathway for the conversion of biomass-derived materials into various compounds (such as...). Figure 1 (As shown). The reaction pathway includes the following steps: (1) Initial conversion: Biomass was hydrolyzed at 80-120℃ to obtain 5-hydroxymethylfurfural (HMF); (2) Oxidation reaction: The HMF is reacted with oxygen at about 100°C to generate 5-hydroxymethyl-2-furanoic acid (HMFA). (3) Cycloaddition reaction: The HMFA was subjected to a Diels-Alder reaction at about 150 °C to obtain p-hydroxymethylbenzoic acid (HMBA) compound; (4) Second oxidation reaction: The HMBA compound is oxidized at 150°C to produce terephthalic acid (TPA). (5) MOF synthesis steps: Zirconium chloride (ZrCl4) and terephthalic acid (TPA) are reacted in an aqueous phase at 100-120℃ for about 24 hours to obtain metal-organic framework (MOF) material UiO-66.

[0058] Example 2: Synthesis of MOF-303 Materials: Aluminum hydroxide (Al(OH)3, 99% purity); pyrazole-3,5-dicarboxylic acid (PZDC, 98% purity); deionized water.

[0059] step: (1) Add 0.8 g Al(OH)3 and 1.6 g PZDC to 20 mL of deionized water and stir for 30 minutes to form a uniform suspension; (2) Add 0.2 mL of acetic acid to adjust the pH to 3 to optimize crystallinity; (3) Transfer the suspension to a stainless steel autoclave lined with polytetrafluoroethylene; (4) Heat at 120℃ for 24 hours; (5) Filtration; washing with deionized water and sustainably sourced ethanol (each time the amount is twice that of the initial reaction solution, and the ethanol is recovered and reused); freeze drying (-20°C, sublimation drying); activation, using nitrogen flow activation (50°C).

[0060] (6) Dry at 80℃ for 12 hours to obtain MOF-303.

[0061] Results: SEM images of the molded MOF (see attached image). Figure 2 The yield of this embodiment is 91%, and the BET specific surface area of ​​the product is 1180 m². 2 / g, water adsorption capacity (30% RH) is 31.5 g / 100 g.

[0062] Example 3: Synthesis of MOF-801 Materials: Zirconium chloride (ZrCl4, 99% purity); fumaric acid (98% purity); deionized water.

[0063] step: (1) Dissolve 0.2 g ZrCl4 and 0.15 g fumaric acid in 20 mL of deionized water; (2) Add 0.2 mL of acetic acid to adjust the pH to 3 to optimize crystallinity; (3) Transfer the above solution to a microwave-resistant high-pressure reaction vessel and seal it. Place the reaction vessel in a microwave reactor and set the reaction conditions as follows: temperature 120℃, power 300 W, reaction time 2 hours. During the reaction, the mixture can be stirred intermittently to ensure uniform heating of the solution. After the microwave reaction is completed, allow it to cool naturally to room temperature. (4) Filtration; washing with deionized water and sustainably sourced ethanol (ethanol recovery); supercritical CO2 drying (50°C, 13 MPa); activation, using argon flow activation (60°C).

[0064] Results: SEM images of the molded MOF are shown below. Figure 3 As shown. The yield of this embodiment is 90%, and the BET specific surface area of ​​the product is 691.05 m². 2 / g, water adsorption capacity (30% RH) is 31.5 g / 100 g.

[0065] Example 4: Synthesis of UiO-66 Materials: Zirconium chloride (ZrCl4, 99% purity); terephthalic acid (H2BDC, 98% purity); deionized water.

[0066] step: (1) Dissolve 0.2 g ZrCl4 in 20 mL of deionized water; (2) Add 0.14 g H2BDC and stir until completely dissolved; (3) Add 0.2 mL of nitric acid (65 wt%) and adjust the pH to 2; (4) Stir at 120℃ for 24 hours; (5) Filtration; washing with deionized water and sustainably sourced ethanol (ethanol recovery); supercritical CO2 drying (50°C, 13 MPa); activation, using nitrogen flow activation (60°C).

[0067] (6) Dry at 100℃ for 12 hours to obtain UiO-66.

[0068] Results: SEM images of the molded MOF are shown below. Figure 4 As shown. The yield of this embodiment is 90%, and the BET specific surface area of ​​the product is 1200 m². 2 / g, water adsorption capacity 30 g / 100 g (30% RH).

[0069] Example 5: Synthesis of MIL-101 Materials: Chromium nitrate nonahydrate (Cr(NO3)3·9H2O, 99% purity); terephthalic acid (H2BDC, 98% purity); deionized water; nitric acid (HNO3, 65 wt%).

[0070] step: (1) Dissolve 2.0 g Cr(NO3)3·9H2O and 0.8 g H2BDC in 20 mL of deionized water.

[0071] (2) Add 0.2 mL of 65 wt% HNO3, adjust the pH to 2, and stir well.

[0072] (3) Transfer the mixture to a 50 mL autoclave lined with polytetrafluoroethylene.

[0073] (4) Heat at 220℃ for 8 hours.

[0074] (5) Filter after cooling to room temperature; wash with deionized water and sustainably sourced ethanol (ethanol recovery); perform supercritical CO2 drying (60°C, 13 MPa); activate using argon flow activation (80°C).

[0075] (6) Dry at 100℃ for 12 hours to obtain MIL-101.

[0076] Results: SEM images of the molded MOF are shown below. Figure 5 As shown. In this embodiment, the yield is >80%, and the BET specific surface area of ​​the product is >3200 m². 2 / g, water adsorption capacity 31.0 g / 100 g (measured under 30% RH conditions).

[0077] Comparative Example 1: Synthesis of UiO-66 by the conventional DMF method Materials: Zirconium chloride (ZrCl4, 99% purity); terephthalic acid (H2BDC, 98% purity); N,N-dimethylformamide (DMF).

[0078] step: (1) Dissolve 0.4 g ZrCl4 and 0.28 g H2BDC in 20 mL DMF.

[0079] (2) Transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene.

[0080] (3) Heat at 120°C for 24 hours.

[0081] (4) After cooling to room temperature, filter and collect the white precipitate, and wash with DMF and ethanol.

[0082] (5) Dry under vacuum at 120°C for 12 hours.

[0083] Results: The yield of this comparative example was 80%, and the BET specific surface area of ​​the product was 1450 m². 2 / g, water adsorption capacity 28.0g / 100g (measured under 30% RH conditions). Compared with Example 3, the yield is lower and the toxic solvent DMF is used.

[0084] Comparative Example 2: Synthesis of MOF-801 without pH control Materials: ZrCl4 (99%), fumaric acid (98%), DMF.

[0085] step: (1) Dissolve 0.2 g ZrCl4 and 0.15 g fumaric acid in 20 mL DMF.

[0086] (2) Heat at 120℃ for 18 hours.

[0087] (3) Filter, wash with DMF and ethanol, and vacuum dry at 120°C.

[0088] Results: The yield of this comparative example was 80%, and the BET specific surface area of ​​the product was 650 m². 2 / g, water adsorption capacity is 28g / 100g (30% RH).

[0089] Comparative Example 3: Synthesis of MOF-303 without the addition of regulators Materials: Aluminum hydroxide (Al(OH)3, 99% purity); pyrazole-3,5-dicarboxylic acid (PZDC, 98% purity); deionized water.

[0090] step: (1) Add 0.8 g Al(OH)3 and 1.6 g PZDC to 20 mL of deionized water and stir for 30 minutes to form a uniform suspension.

[0091] (2) No nitric acid is added to adjust the pH.

[0092] (3) Transfer the suspension to a stainless steel autoclave lined with polytetrafluoroethylene.

[0093] (4) Heat at 120°C for 24 hours.

[0094] (5) After cooling to room temperature, filter and collect the white product, and wash with deionized water and ethanol.

[0095] (6) Dry at 80℃ for 12 hours to obtain MOF-303.

[0096] Results: The yield of this comparative example was 75%, and the BET specific surface area of ​​the product was 1000 m². 2 / g, water adsorption capacity was 28.0g / 100g (measured under 30% RH conditions). Compared with Example 1, both the yield and specific surface area were lower, indicating that the regulator had a significant impact on the synthesis of MOF-303.

[0097] Comparative Example 4: Synthesis of MIL-101 by the conventional high temperature and high pressure method Materials: Chromium nitrate nonahydrate (Cr(NO3)3·9H2O, 99% purity); terephthalic acid (H2BDC, 98% purity); DMF.

[0098] step: (1) Dissolve 2.0 g Cr(NO3)3·9H2O and 0.8 g H2BDC in 20 mL DMF; (2) Heat at 250℃ and 40 bar for 12 hours; (3) After filtration, wash with DMF and ethanol, and dry under vacuum at 120°C.

[0099] Results: The yield of this comparative example was 72%, and the BET specific surface area of ​​the product was 3000 m². 2 / g, water adsorption capacity 28 g / 100 g (30% RH). Comparative conclusion: The method of the present invention has a higher yield (80%), a 33% shorter reaction time (8 hours vs. 12 hours), and does not require high-pressure equipment.

[0100] A systematic comparison between the method of this invention and traditional methods: The preparation method of this invention is significantly superior to traditional methods in terms of technical feasibility, environmental friendliness, and economy, as detailed below: Technical parameter optimization: Reaction conditions: Traditional methods rely on high temperature and pressure (e.g., 250°C, 40 bar) and toxic solvents (e.g., DMF, HF), while the method of this invention uses a water-based system, reducing the reaction temperature to room temperature to 220°C, and the pressure to atmospheric pressure. For example, the synthesis time of MOF-801 is shortened from 24 hours in the traditional method to 2 hours (microwave-assisted), and energy consumption is reduced by 40%.

[0101] Yield and stability: The yield of the method of this invention is stable at 80%-91%, which is a significant improvement over the traditional method (60%-85%), and the product performance is consistent (e.g., the specific surface area of ​​UiO-66 reaches 1200 m²). 2 / g, compared with the traditional method 1450 m 2 The water adsorption capacity is comparable to that of g, but it is increased by 26% to 30.0 g / 100 g (30% RH).

[0102] Environmental and safety advantages: Solvent substitution: In traditional processes, the high toxicity of DMF (LD50: 5 g / kg) and HF leads to wastewater treatment costs accounting for 15%-20% of the total cost, and their biodegradability is poor (half-life > 100 days); the method of this invention completely eliminates toxic solvents and adopts water or solvent-free systems to achieve zero toxic waste discharge.

[0103] Carbon emissions: The method of this invention can use mild reaction conditions with microwave-assisted heating, which reduces the overall carbon emissions by more than 50% compared with the traditional hydrothermal method (the energy consumption of this invention is 0.5 kWh, which is better than the 1.0 kWh of the traditional hydrothermal method).

[0104] Economic benefits and scalability: Simplified process: Traditional methods require multiple solvent replacements and high-pressure equipment maintenance, while the post-treatment of the method of this invention only requires water / ethanol washing, reducing equipment investment by 40% and making it more suitable for industrial scale-up (such as 500L reactors).

[0105] Product application performance: The UiO-66 prepared by the method of this invention exhibits superior water adsorption performance (30.0 g / 100 g) in low humidity environments (20%-30% RH). Compared with UiO-66 synthesized by the traditional hydrothermal method (Comparative Example 1, 28.0 g / 100 g), its cycle stability is improved, making it particularly suitable for all-weather water capture equipment in arid regions. Compared with traditional methods, this invention has the following significant advantages: Environmentally friendly: completely avoids toxic solvents such as DMF and HF, reducing carbon emissions by more than 50%; Cost-effective: raw material costs are reduced by 20%-30%, and waste treatment costs are reduced by 90%; Highly efficient and energy-saving: microwave-assisted reaction time is shortened to the minute level, reducing energy consumption by 40%; Excellent performance: water adsorption capacity is increased by 26%. A comparison of the preparation method of this invention with traditional methods is shown in Table 1.

[0106] Table 1 Comparison of the preparation method of the present invention with traditional methods

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing MOF materials, characterized in that, Includes the following steps: The metal salt and organic ligand used for MOF material preparation were mixed in water to obtain a solution; The pH of the solution was adjusted to 2-5 by adding a pH adjuster to carry out the reaction. After the reaction was completed, the reaction product was dried to obtain the MOF material. The reaction temperature is 110–230°C, the drying method is supercritical CO2 drying or freeze drying, and the MOF material includes MOF-303, MOF-801, UiO-66 or MIL-101.

2. The preparation method according to claim 1, characterized in that, The metal salt used to prepare the MOF-303 is Al(OH)3, and the organic ligand is pyrazole-3,5-dicarboxylic acid; The molar ratio of the metal salt to the organic ligand of the MOF-303 is (0.8–1.2):1; The reaction temperature of the metal salt and organic ligand of MOF-303 is 110–130 °C.

3. The preparation method according to claim 1, characterized in that, The metal salt used to prepare MOF-801 is ZrCl4, and the organic ligand is fumaric acid; The molar ratio of the metal salt to the organic ligand of the MOF-801 is 1:(1.5 to 1.9); The reaction temperature of the metal salt and organic ligand of MOF-801 is 120–170 °C.

4. The preparation method according to claim 1, characterized in that, The metal salt used to prepare the UiO-66 is ZrCl4, and the organic ligand is terephthalic acid; The molar ratio of the metal salt to the organic ligand of the UiO-66 is (0.9–1.1):1; The reaction temperature of the metal salt and organic ligand of UiO-66 is 110–130 °C.

5. The preparation method according to claim 1, characterized in that, The metal salt used to prepare MIL-101 is chromium nitrate nonahydrate, and the organic ligand is terephthalic acid; The molar ratio of the metal salt to the organic ligand in MIL-101 is (0.8–1.2):1; The reaction temperature of the metal salt and organic ligand of MIL-101 is 200–230 °C.

6. The preparation method according to claim 1, characterized in that, The solution is heated to the reaction temperature using microwave-assisted heating.

7. The preparation method according to claim 1, characterized in that, The pH adjuster includes acetic acid, citric acid, or nitric acid.

8. The preparation method according to claim 1, characterized in that, After the reaction is completed, the process also includes solid-liquid separation to collect the reaction products and washing the reaction products. The solvents used for washing include water and ethanol.

9. The preparation method according to any one of claims 1-8, characterized in that, The drying process also includes activating the reaction products.

10. The application of the MOF-801 material prepared by the preparation method according to any one of claims 1-9 in atmospheric water collection.

Images