Efficient and environment-friendly method for synthesizing high-performance MIL101

Abstract

The invention discloses an efficient and environment-friendly method for synthesizing high-performance MIL101, which comprises the following steps of: 1, weighing metal salt, ligand and mineralizer, and mixing in a beaker according to a molar ratio; step 2, adding pure water, carrying out ultrasonic dispersion for 3-120 minutes, then putting into a continuous flow reactor, and reacting for 2-8 hours in an environment of 140-240 DEG C, so as to obtain an MOFs precursor solution; step 3, putting the MOFs precursor solution into a spray dryer; and 4, a MIL-101 crude product is obtained through a spray dryer collector, the MIL-101 crude product is washed with hot pure water twice for 2 hours, centrifugation, drying and grinding are performed to obtain a MIL-101 finished product, and the metal salt is one or more of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate and chromium nitrate nonahydrate. According to the preparation method, the solution containing the MOFs precursor is atomized into the microdroplets and is quickly dried, so that the particle size and morphology are effectively controlled, the dispersity is improved, the reaction time of the MOFs is shortened, the use of a solvent is reduced, and the preparation method is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of MIL101 synthesis, and specifically to a method for efficiently and environmentally synthesizing high-performance MIL101. Background Art

[0002] MIL-101 is a metal-organic framework (MOFs) material, which shows great application potential in the fields of gas storage, separation, and catalysis due to its unique pore structure and high specific surface area. The pore structure of this material is formed by the self-assembly of metal nodes and organic ligands. The metal nodes can be different metal elements such as chromium, iron, aluminum, titanium, vanadium, scandium, and manganese, while the organic ligands are usually terephthalic acid (BDC) or its derivatives. MIL-101 has the following remarkable characteristics: it has a huge unit cell volume and high specific surface area, which creates conditions for providing abundant active sites; high porosity helps the adsorption and diffusion of substances; excellent thermal stability, capable of maintaining the structural stability at higher temperatures; containing unsaturated active sites, which makes MIL-101 perform excellently in catalytic reactions. These characteristics make MIL-101 an ideal material in the fields of water treatment, gas storage, and catalytic conversion, etc.

[0003] Although MIL-101 has many advantages, there are some problems in synthesizing MIL-101 by the traditional hydrothermal synthesis method, such as long reaction time, the need for a large amount of organic reagents for washing and purification, and not high specific surface area, etc.;

[0004] For example, in a method for preparing a magnetic MOFs-based Pb(II) ion-imprinted polymer described in Patent CN117430820A, the method for synthesizing MIL-101 is to dissolve chromium(III) chloride hexahydrate and terephthalic acid in deionized water, and after ultrasonic treatment, put it into a Teflon liner for hydrothermal reaction. The reaction conditions are heating at 150 °C for 8 hours, and then washing with ethanol for 8 hours and pure water for 2 hours, and the whole process takes a long time;

[0005] In a method for preparing and applying a titanium dioxide metal-organic framework forward osmosis membrane described in Patent CN116059855A, the method for synthesizing MIL-101(Cr) / TiO2 involves dissolving chromium(III) nitrate nonahydrate and phthalic acid in water, adding tetramethylammonium hydroxide and titanium dioxide and mixing them, and then putting it into a Teflon liner for hydrothermal reaction. The high-temperature reaction conditions are heating at 180 °C for 24 hours, and subsequent washing and purification are also required using DMF, absolute ethanol, and pure water in sequence. This process not only has a long reaction time but also requires a large amount of organic reagents for washing and purification.

[0006] Therefore, the present invention provides a method for efficiently and environmentally synthesizing high-performance MIL101 to solve the above problems. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides a method for efficiently and environmentally synthesizing high-performance MIL-101, which solves the above problems.

[0008] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for efficiently and environmentally synthesizing high-performance MIL-101, the steps are as follows:

[0009] First step, weigh metal salts, ligands and mineralizers, and mix them in a beaker according to the molar ratio;

[0010] Second step, add pure water, first disperse it by ultrasound for 3 - 120 min, then put it into a continuous flow reactor, and react for 2 - 8 h at an environment of 140 - 240 °C to obtain a MOFs precursor solution;

[0011] Third step, place the MOFs precursor solution in a spray dryer;

[0012] Fourth step, obtain the crude MIL-101 through the collector of the spray dryer, wash it with hot pure water twice for 2 hours, centrifuge, dry, and grind it to obtain the finished MIL-101.

[0013] Preferably, the metal salt is one or more of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, and chromium nitrate nonahydrate.

[0014] Preferably, the ligand is one or several of terephthalic acid, diaminoterephthalic acid, disodium terephthalate, vinyl terephthalic acid, and dibutyl terephthalate.

[0015] Preferably, the mineralizer is one or several of hydrofluoric acid, benzoic acid, acetic acid, 2-methylimidazole, and sodium acetate.

[0016] Preferably, the molar ratio of the metal salt, ligand and mineralizer is 1 mol : 1 - 1.2 mol : 2.05 - 2.5 mol.

[0017] Preferably, the ratio of pure water to terephthalic acid is 2 mol : 10000 ml.

[0018] Preferably, the spray dryer is provided with:

[0019] An inlet temperature adjustment module for controlling the inlet temperature of the spray dryer;

[0020] A compressed air flow rate adjustment module for controlling the compressed air flow rate;

[0021] A feed rate adjustment module for controlling the feed rate;

[0022] A solid content adjustment module for controlling the solid content;

[0023] A three-fluid nozzle for mixing a ligand and a metal salt in a drying chamber of a spray dryer;

[0024] A double-layer spoiler for intervening in the spray to increase the reaction time between the metal and the ligand.

[0025] Preferably, the feeding rate of the spray dryer is 3 - 20 ml / min, the flow rate of compressed air is 50 - 200 ml / min, and the inlet temperature is 150 - 240 °C.

[0026] Beneficial effects

[0027] The present invention provides a method for efficiently and environmentally friendly synthesizing high-performance MIL101. Compared with the prior art, it has the following beneficial effects:

[0028] This method for efficiently and environmentally friendly synthesizing high-performance MIL101 can atomize a solution containing MOFs precursors into microdroplets and quickly dry them, inducing the reaction between metal ions and ligands within the droplets to form MOFs nanoparticles. These nanoparticles aggregate and fuse to form a dense or hollow spherical MOFs structure, while the solvent completely evaporates. Finally, the MIL-101 product is collected by a collector, effectively controlling the particle size and morphology, improving the dispersibility, reducing the reaction time of MOFs, reducing the solvent usage, and being suitable for large-scale production. Description of the drawings

[0029] Figure 1 is a flow chart of the present invention;

[0030] Figure 2 is an XRD test image of Example 1 and the control example of the present invention;

[0031] Figure 3 is an isotherm image of nitrogen adsorption and desorption of Example 1 and the control example of the present invention;

[0032] Figure 4 is a schematic diagram of the spray dryer device of the present invention. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0034] Please refer to Figure 1 , a method for efficiently and environmentally friendly synthesizing high-performance MIL101, the steps are as follows:

[0035] First step: Weigh the metal salt, ligand and mineralizer, and mix them in a beaker according to the molar ratio.

[0036] Second step: Add pure water, first disperse it by ultrasound for 3 - 120 min, and then place it in a continuous flow reactor to react for 2 - 8 h at an environment of 140 - 240 °C to obtain the MOFs precursor solution.

[0037] Third step: Place the MOFs precursor solution in a spray dryer.

[0038] Fourth step: Obtain the crude MIL - 101 through the collector of the spray dryer, wash it with hot pure water twice for 2 hours, centrifuge, dry, and grind to obtain the finished MIL - 101.

[0039] More specifically, the metal salt is one or more of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, and chromium nitrate nonahydrate.

[0040] It can be understood that the ligand is one or several of terephthalic acid, diaminoterephthalic acid, disodium terephthalate, vinyl terephthalic acid, and dibutyl terephthalate.

[0041] Furthermore, the mineralizer is one or several of hydrofluoric acid, benzoic acid, acetic acid, 2 - methylimidazole, and sodium acetate.

[0042] More specifically, the molar ratio of the metal salt, ligand and mineralizer is 1 mol: 1 - 1.2 mol: 2.05 - 2.5 mol.

[0043] More specifically, the ratio of pure water to terephthalic acid is 2 mol: 10000 ml.

[0044] Furthermore, the spray dryer is provided with:

[0045] An inlet temperature adjustment module for controlling the inlet temperature of the spray dryer.

[0046] A compressed air flow rate adjustment module for controlling the compressed air flow rate.

[0047] A feed rate adjustment module for controlling the feed rate.

[0048] A solid content adjustment module for controlling the solid content.

[0049] A three - liquid nozzle for mixing the ligand and the metal salt in the drying chamber of the spray dryer.

[0050] A double - layer spoiler for intervening in the spray to increase the reaction time between the metal and the ligand.

[0051] Furthermore, the feeding rate of the spray dryer is 3 - 20 ml / min, the compressed air flow rate is 50 - 200 ml / min, and the inlet temperature is 150 - 240 °C.

[0052] To further illustrate that the synthesis of MIL101 by the above method is more efficient and more environmentally friendly, specific examples will be listed below for further description;

[0053] Example 1:

[0054] Weigh chromium(III) nitrate nonahydrate, phthalic acid, and sodium acetate (the ratio of the three is 0.02 mol : 0.02 mol : 0.041 mol) and mix them in a beaker, then add 100 ml of pure water. First, disperse them by ultrasound for 30 min, and then place them in a continuous flow reactor to react at 180 °C for 4 h to obtain a MOFs precursor solution. Place the MOFs precursor solution in a spray dryer, set the feeding rate to 5 ml / min, the flow rate to 100 ml / min, and the inlet temperature to 220 °C as the synthesis conditions. After passing through the spray dryer collector, obtain the crude MIL101. After washing twice with hot pure water for 2 h, centrifuging, drying, and grinding, obtain the finished MIL101;

[0055] Example 2:

[0056] Weigh chromium(III) chloride hexahydrate, phthalic acid, and sodium hydroxide (the ratio of the three is 0.02 mol : 0.02 mol : 0.041 mol) and mix them in a beaker, then add 100 ml of pure water. First, disperse them by ultrasound for 60 min, and then place them in a continuous flow reactor to react at 160 °C for 2 h to obtain a MOFs precursor solution. Place the MOFs precursor solution in a spray dryer, set the feeding rate to 5 ml / min, the flow rate to 50 ml / min, and the inlet temperature to 220 °C as the synthesis conditions. After passing through the spray dryer collector, obtain the crude MIL101. After washing twice with hot pure water for 2 h, centrifuging, drying, and grinding, obtain the finished MIL101;

[0057] Example 3:

[0058] Weigh chromium(III) chloride hexahydrate, phthalic acid, and hydrofluoric acid (the ratio of the three is 0.02 mol : 0.02 mol : 0.041 mol) and mix them in a beaker, then add 100 ml of pure water. First, disperse them by ultrasound for 30 min, and then place them in a continuous flow reactor to react at 180 °C for 4 h to obtain a MOFs precursor solution. Place the MOFs precursor solution in a spray dryer, set the feeding rate to 10 ml / min, the flow rate to 100 ml / min, and the inlet temperature to 240 °C as the synthesis conditions. After passing through the spray dryer collector, obtain the crude MIL101. After washing twice with hot pure water for 2 h, centrifuging, drying, and grinding, obtain the finished MIL101;

[0059] Control example: Synthesis of MIL-101 using the traditional hydrothermal synthesis method

[0060] Weigh 2 g of chromium(III) nitrate nonahydrate and 0.82 g of terephthalic acid, add them to 25 mL of deionized water and 25 mL of 0.05 mol / L hydrogen fluoride solution, stir for 30 min, then transfer the mixture to a hydrothermal reaction kettle lined with polytetrafluoroethylene. After sealing, place it in a constant-temperature blast drying oven preheated to 220 °C for constant-temperature crystallization for 8 h. After the reaction, let the hydrothermal reaction kettle stand and cool to room temperature. After the sample is thoroughly washed and filtered by suction, place it in a drying oven and dry at 150 °C for 5 h to obtain MIL-101 crystals. Weigh 0.2 g of MIL-101 crystals into a hydrothermal reaction kettle and add 60 mL of absolute ethanol. After sealing, place it in a constant-temperature blast drying oven and keep it at 100 °C for 20 h, then reflux the sample with pure water at 60 °C for 10 h. Finally, place the sample in a constant-temperature blast drying oven and dry at 150 °C for 5 h to obtain the control example sample.

[0061] More specifically, the XRD tests of Example 1 and the control example are as Figure 2 shown. The main characteristic peaks of Example 1 are consistent with those of the control example, proving that the structure of MIL-101 has been successfully synthesized.

[0062] The nitrogen adsorption-desorption isotherms of Example 1 and the control example are as Figure 3 shown. By comparing the nitrogen adsorption and desorption curves of Example 1 and the control example, we found that Example 1 is comprehensively superior to the control example in terms of nitrogen adsorption and desorption performance. This indicates that the pore structure of Example 1 is more developed, providing more adsorption sites. Combining with the specific surface area data, the specific surface area of Example 1 is 3794.96 m 2 / g, while that of the control example is 3134.19 m 2 / g. This means that the specific surface area of Example 1 has increased by 21.08% compared to the control example, which is a significant increase, indicating that Example 1 has a higher porosity and more available surface area in structure, proving that the performance of MIL-101 synthesized in Example 1 is stronger than that of the control example.

[0063] The comparison of the synthesis processes of Example 1 and the control example is shown in the following table:

[0064]

[0065]

[0066] As can be seen from the above table, the synthesis time of Example 1 is about 8.5 hours, which is much less than the 48.5 hours required for the control example, and is only 17.5% of the time of the control example. This significantly reduced reaction time, combined with the low energy consumption characteristics of Example 1, the absence of the need for a large amount of organic solvent washing, and the fact that no toxic ammonium fluoride was added during the synthesis, indicates that Example 1 has obvious advantages in terms of synthesis efficiency and environmental friendliness;

[0067] In summary, for the problems existing in the traditional hydrothermal synthesis method of MIL-101, such as long reaction time, the need for a large amount of organic reagents for washing and purification, and low specific surface area performance, using the spray drying method for synthesis optimization is an effective solution. The spray drying method atomizes the solution containing MOFs precursors into microdroplets and quickly dries them, which not only significantly reduces the synthesis time but also avoids using a large amount of organic solvents for washing and purification, thereby reducing the environmental impact and production costs;

[0068] The MIL-101 synthesized by the spray drying method exhibits excellent performance in terms of nitrogen adsorption and desorption isotherms and specific surface area analysis. The specific surface area has increased by 21.08%, which indicates that the MIL-101 synthesized by the spray drying method has a higher porosity and more active sites, thereby enhancing its application potential in fields such as gas adsorption and separation;

[0069] In addition, the synthesis time of MIL-101 by the spray drying method is only 17.5% of that of the traditional hydrothermal synthesis method, which greatly shortens the production cycle and improves the production efficiency. The MIL-101 synthesized by the spray drying method also has other advantages, such as high energy utilization rate, controllable morphology and size of the synthesized product, and high product yield. These characteristics make the MIL-101 synthesized by the spray drying method have great potential in large-scale production and industrial applications.

[0070] Meanwhile, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0071] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0072] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently and environmentally synthesizing high-performance MIL101, characterized in that: The steps are as follows: First step, weigh the metal salt, ligand and mineralizer, and mix them in a beaker according to the molar ratio; Second step, add pure water, first disperse it by ultrasound for 3 - 120 min, then put it into a continuous flow reactor and react for 2 - 8 h at an environment of 140 - 240 °C to obtain a MOFs precursor solution; Third step, place the MOFs precursor solution in a spray dryer; Fourth step, obtain the crude MIL - 101 through the collector of the spray dryer, wash it with hot pure water twice for 2 hours, centrifuge, dry, and grind to obtain the finished MIL - 101.

2. A method for efficiently and environmentally synthesizing high-performance MIL-101 according to claim 1, characterized in that: The metal salt is one or more of ferric chloride hexahydrate, chromium chloride hexahydrate, ferric nitrate nonahydrate, and chromium nitrate nonahydrate.

3. A method for efficiently and environmentally synthesizing high-performance MIL101 according to claim 1, characterized in that: The ligand is one or several of terephthalic acid, diaminoterephthalic acid, disodium terephthalate, vinyl terephthalic acid, and dibutyl terephthalate.

4. A method for efficiently and environmentally synthesizing high-performance MIL-101 according to claim 1, characterized in that: The mineralizer is one or several of hydrofluoric acid, benzoic acid, acetic acid, 2 - methylimidazole, and sodium acetate.

5. A method for efficiently and environmentally friendly synthesizing high-performance MIL-101 according to claim 1, characterized in that: The molar ratio of the metal salt, ligand and mineralizer is 1 mol: 1 - 1.2 mol: 2.05 - 2.5 mol.

6. A method for efficiently and environmentally synthesizing high-performance MIL-101 according to claim 1, characterized in that: The ratio of pure water to terephthalic acid is 2 mol: 10000 ml.

7. A method for efficiently and environmentally synthesizing high-performance MIL-101 according to claim 1, characterized in that: The spray dryer is provided with: An inlet temperature adjustment module for controlling the inlet temperature of the spray drying agent; A compressed air flow rate adjustment module for controlling the compressed air flow rate; A feed rate adjustment module for controlling the feed rate; A solid content adjustment module for controlling the solid content; A three - liquid nozzle for mixing the ligand and the metal salt in the drying chamber of the spray dryer; A double - layer spoiler for intervening in the spray to increase the reaction time between the metal and the ligand.

8. A method for efficiently and environmentally synthesizing high-performance MIL-101 according to claim 1, characterized in that: The feed rate of the spray dryer is 3 - 20 ml / min, the compressed air flow rate is 50 - 200 ml / min, and the inlet temperature is 150 - 240 °C.

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