A method for continuous preparation of MOF material using supergravity technology in aqueous phase

Abstract

The application discloses a method for continuously preparing MOF materials in water phase by using a supergravity technology, and comprises the following steps: S1, weighing metal salt and dissolving the metal salt in a deionized water solution at normal temperature, and recording the solution as reaction liquid A; S2, weighing organic ligand and dissolving the organic ligand in an alkali solution at normal temperature, and recording the solution as reaction liquid B; S3, starting a supergravity reactor, and simultaneously introducing the reaction liquid A and the reaction liquid B into the supergravity reactor by a peristaltic pump to perform a precipitation crystallization reaction, so as to prepare a MOF material suspension, wherein the supergravity reactor is selected from an external circulation rotating packed bed; and S4, performing centrifugation, washing, activation and drying on the suspension, so as to obtain MOFs. The method is green and environment-friendly, the prepared product has high crystallinity, large specific surface area, uniform particle distribution, regular morphology, and the average particle size is 20 nm-6 microns, and the size is controllable.

Description

Technical Field

[0001] This invention relates to the field of metal-organic framework material preparation technology; more specifically, it relates to a method for continuously preparing MOF materials in an aqueous phase using hypergravity technology. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of novel porous materials composed of metal ions and organic ligands linked by coordination bonds. They are characterized by ultra-high porosity and extremely large surface area, flexible and tunable structure, and controllable pore size, possessing rich application potential and finding wide applications in gas adsorption, separation, catalysis, sensing, and biomedicine.

[0003] Typically, the synthesis of MOFs generally involves a solvothermal reaction of a solution containing metal salts and ligands in an organic solvent (e.g., N,N-dimethylformamide, ethanol) or a mixture of organic solvent and water. In this process, the large-scale use of organic solvents such as DMF increases costs and introduces safety risks and environmental hazards, hindering the industrialization of MOFs. Solvothermal reactions require high temperatures and long reaction times, making large-scale continuous production impossible. Furthermore, some organic solvents are prone to decomposition, generating substantial amounts of waste byproducts, which may affect the functionality and performance of MOF products.

[0004] In recent years, some new technologies that do not require organic solvents, such as mechanical synthesis and microwave synthesis, have been developed. However, these methods often require complex equipment and the synthesis process is relatively complicated. Finding a simple and feasible general method that does not use organic solvents is an important direction for the large-scale industrial production of MOF materials. Among all solvents, water is mild, readily available, and inexpensive. Synthesis in water is considered the safest, cheapest, and simplest post-processing method. Compared with organic solvents, water is safe, environmentally friendly, inexpensive, readily available, and has simple post-processing. In addition, organic solvents such as DMF in the pores of MOF materials are usually difficult to completely eliminate, thus requiring long-term activation, and the activation process also requires a large amount of organic solvent. Water can easily be removed from the pores. Using water as a solvent can reduce the use of organic solvents in the activation process, and the activation time is also greatly shortened, making the synthesis process simpler and greener.

[0005] Rotating packed bed (RPB) with supergravity, as a process intensification device, generates a great centrifugal force. Liquids pass through the porous packing of the device and diffuse or break into micro- and nano-droplets, threads, and thin films under strong shearing. Micro-mixing and mass transfer between fluid elements are highly enhanced, and the micro-mixing process is greatly strengthened. The micro-mixing time is less than the nucleation induction time, and the particle nucleation and growth process can be carried out in a micro-uniform ideal environment.

[0006] There are already reports on the use of hypergravity technology to prepare MOF materials, such as Chinese Patent Publication No. CN112341630A, entitled "Method for Continuous Preparation of Nanoscale Metal-Organic Framework Materials Using Hypergravity Technology," and Chinese Patent Publication No. CN114891233A, entitled "Method for Preparation of Nanoscale Zirconium-based MOF Materials Using an Internal Circulation Rotating Packed Bed." These methods can efficiently prepare MOF materials in organic phase synthesis. However, these methods have drawbacks in aqueous phase synthesis. The organic ligands in MOF materials are mostly large-molecule polycarboxylic acids, which are extremely difficult to dissolve in water. In aqueous phase synthesis, a large amount of undissolved organic ligands is difficult to react with metal ions, resulting in low reaction conversion rate, low yield, and low product purity due to the presence of unreacted organic ligands. Undissolved organic ligands can also become stuck in the equipment packing, making cleaning difficult and causing significant ligand waste.

[0007] Furthermore, the strong association between water and metal ions makes it difficult for metal ions and organic ligands to form coordination bonds in the aqueous phase, inhibiting MOF nucleation and resulting in a long reaction time. Aqueous-phase synthesized MOFs tend to form large single crystals, and the uncontrollable size of these crystals also hinders the development of aqueous MOF synthesis. Therefore, developing a continuous, rapid, and green synthesis route for large-scale MOF material preparation with controllable material size, while remaining technically and economically feasible, is a significant challenge. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a method for the continuous preparation of MOF materials in aqueous phase using supergravity technology. This method is green and environmentally friendly, and the products obtained have high crystallinity, large specific surface area, uniform particle distribution, regular morphology, average particle size of 20nm-6μm, and controllable size.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0011] S1. Weigh out a metal salt and dissolve it in a deionized aqueous solution at room temperature, and record it as reaction solution A;

[0012] S2. Weigh out the organic ligand and dissolve it in an alkaline solution at room temperature, and record it as reaction solution B;

[0013] S3. Start the hypergravity reactor and simultaneously introduce reaction solution A and reaction solution B into the hypergravity reactor by a peristaltic pump to carry out precipitation and crystallization reaction; obtain MOF material suspension; the hypergravity reactor is selected from external circulation rotating packed bed;

[0014] S4. Centrifuge, wash, activate, and dry the suspension to obtain MOF products.

[0015] As a further improvement to the technical solution, in step S1, the metal salt is selected from one or more of soluble zinc salts, magnesium salts, cobalt salts, nickel salts, aluminum salts, manganese salts, iron salts, copper salts, and cadmium salts.

[0016] Preferably, in step S1, the concentration of the metal salt in the reaction solution A is 10-1000 mM.

[0017] As a further improvement to the technical solution, in step S1, a coordination competition additive may be added to the reaction solution A. The coordination competition additive is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, hydrofluoric acid, benzoic acid, citric acid, salicylic acid, hydrochloric acid, nitric acid, sulfuric acid, chloroacetic acid, and trifluoroacetic acid.

[0018] Preferably, in step S1, the molar ratio of the coordination competing additive to the metal salt is (0-1.5):1.

[0019] As a further improvement to the technical solution, in step S2, the organic ligand is selected from one or more of 2,5-dihydroxyterephthalic acid, pyromellitic acid, terephthalic acid, 2-aminopyromellitic acid, 2-aminoterephthalic acid, 2-hydroxyterephthalic acid, 2,5-diaminoterephthalic acid, 4,4'-biphenyl dicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid, fumaric acid, and 2,5-thiophene dicarboxylic acid.

[0020] Preferably, in step S2, the concentration of the organic ligand solution is 10-1000 mM.

[0021] As a further improvement to the technical solution, in step S2, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium formate, sodium propionate, sodium butyrate, sodium benzoate, triethylamine, ethylenediamine, and urea; the molar ratio of the alkali to the organic ligand in the reaction solution B is (0.1-6):1.

[0022] As a further improvement to the technical solution, in step S3, the reaction temperature of the precipitation crystallization reaction is 5-90℃.

[0023] Preferably, in step S3, the volumetric flow rates of reaction solution A and reaction solution B injected into the hypergravity reactor by a peristaltic pump are both 50-600 mL / min.

[0024] Preferably, in step S3, the rotor speed of the external circulation rotary filling bed is 500-2850 rpm; more preferably, the rotor speed of the external circulation rotary filling bed is 500-2500 rpm.

[0025] As a further improvement to the technical solution, in step S4, the solvent used for washing and activation is one or more of deionized water, methanol, acetone, ethanol, N,N'-dimethylformamide, N,N'-dimethylacetamide, N,N'-diethylformamide, tetrahydrofuran, chloroform, and dichloromethane.

[0026] Preferably, in step S4, the washing and activation method involves continuously replacing the solvent 2-6 times.

[0027] Preferably, in step S4, the drying method is vacuum drying, the drying temperature is 50-180℃, and the drying time is 2-20h.

[0028] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0029] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0030] Compared with the prior art, the present application has the following beneficial effects :

[0031] 1) This invention utilizes ultragravity aqueous phase synthesis of metal-organic framework materials, and the resulting product has high crystallinity, large specific surface area, uniform particle distribution, regular morphology, and an average particle size of 20nm-6μm.

[0032] 2) In the process of preparing metal-organic framework compounds, this invention avoids the use of organic solvents in conventional synthesis methods. Instead, it uses deionized water as a solvent and synthesizes MOF materials rapidly at lower temperatures under alkaline-assisted deprotonation conditions. This method is green, environmentally friendly, safe, and low in cost.

[0033] 3) This invention enables large-scale, continuous preparation with a simple process. By changing conditions such as the rotation speed of the supergravity, the feed flow rate, and the amount of coordination competing additives, the particle size of the product can be adjusted, achieving large-scale, green, and controllable continuous preparation, providing a new approach for the synthesis and industrialization of metal-organic framework materials. Attached Figure Description

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Figure 1 Comparison of the MOF-74-Zn material prepared in Example 1 with the simulated XRD spectrum;

[0036] Figure 2 Scanning electron microscope (SEM) image of the MOF-74-Zn material prepared in Example 1;

[0037] Figure 3 Comparison of the MOF-74-Mg material prepared in Example 2 with the simulated XRD spectrum;

[0038] Figure 4 Scanning electron microscope (SEM) images of the MOF-74-Mg material prepared in Example 2;

[0039] Figure 5 Scanning electron microscope (SEM) images of the MOF-74-Ni material prepared in Example 3;

[0040] Figure 6 Transmission electron microscope (TEM) image of the MOF-74-Co material prepared in Example 4;

[0041] Figure 7 Comparison of the HKUST-1 material prepared in Example 5 with the simulated XRD spectrum;

[0042] Figure 8 Here is a scanning electron microscope image of the HKUST-1 material prepared in Example 5;

[0043] Figure 9 Scanning electron microscope (SEM) image of the MOF-74-Zn material prepared in Example 6;

[0044] Figure 10 Scanning electron microscope (SEM) image of the MOF-74-Zn material prepared in Example 7;

[0045] Figure 11 Here is a scanning electron microscope image of the HKUST-1 material prepared in Example 8;

[0046] Figure 12 To compare the simulated XRD pattern of the material prepared in Comparative Example 1 with that of MOF-74-Zn;

[0047] Figure 13 The image shows a scanning electron microscope (SEM) image of the material prepared in Comparative Example 3. Detailed Implementation

[0048] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0049] As one aspect of the present invention, a method for continuous preparation of MOF materials in aqueous phase using supergravity technology is characterized by comprising the following steps:

[0050] S1. Weigh out a metal salt and dissolve it in a deionized aqueous solution at room temperature, and record it as reaction solution A;

[0051] S2. Weigh out the organic ligand and dissolve it in an alkaline solution at room temperature, and record it as reaction solution B;

[0052] S3. Start the hypergravity reactor and simultaneously introduce reaction solution A and reaction solution B into the hypergravity reactor by a peristaltic pump to carry out precipitation and crystallization reaction; obtain MOF material suspension; the hypergravity reactor is selected from external circulation rotating packed bed;

[0053] S4. Centrifuge, wash, activate, and dry the suspension to obtain MOF products.

[0054] In step S2 of this invention, the organic ligands required for MOF material synthesis are mostly large-molecule polycarboxylic acids, which have very low solubility in aqueous solution, resulting in low reaction conversion rate, low yield, and unreacted organic ligands mixed in the product, leading to low product purity. To solve this problem, a certain amount of alkali is added to the system. The alkali reacts with the organic ligands to generate the corresponding carboxylate salts. The ionized carboxylate salts have high solubility in water, thus providing an environment for homogeneous nucleation and growth of the material. In addition to dissolving the ligands in water, the addition of alkali can also complete the deprotonation process of the organic ligands during the preparation of the precursor, accelerating the combination of the organic ligands with metal ions, thereby accelerating the nucleation and growth process. The reaction is completed in a shorter time and at a lower temperature. Therefore, MOFs can be synthesized efficiently in aqueous phase under mild conditions.

[0055] In some embodiments, in step S1, the metal salt is selected from one or more of soluble zinc salts, magnesium salts, cobalt salts, nickel salts, aluminum salts, manganese salts, iron salts, copper salts, and cadmium salts.

[0056] In some embodiments, in step S1, the concentration of the metal salt in the reaction solution A is 10-1000 mM.

[0057] In some embodiments, in step S1, a coordination competition additive is further added to the reaction solution A. The coordination competition additive is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, hydrofluoric acid, benzoic acid, citric acid, salicylic acid, hydrochloric acid, nitric acid, sulfuric acid, chloroacetic acid, and trifluoroacetic acid.

[0058] In some embodiments, in step S1, the molar ratio of the coordination competing additive to the metal salt is (0-1.5):1.

[0059] In some embodiments, in step S2, the organic ligand is selected from one or more of 2,5-dihydroxyterephthalic acid, pyromellitic acid, terephthalic acid, 2-aminopyromellitic acid, 2-aminoterephthalic acid, 2-hydroxyterephthalic acid, 2,5-diaminoterephthalic acid, 4,4'-biphenyl dicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid, fumaric acid, and 2,5-thiophene dicarboxylic acid.

[0060] In some embodiments, in step S2, the concentration of the organic ligand solution is 10-1000 mM, such as, but not limited to, 10-800 mM, 10-600 mM, 10-400 mM, 10-200 mM, 10-100 mM, 100-1000 mM, 100-800 mM, 100-600 mM, 100-400 mM, 100-200 mM, 200-1000 mM, 200-800 mM, 200-600 mM, 200- 400mM, 300-1000mM, 300-800mM, 300-600mM, 300-400mM, 400-1000mM, 400-800mM, 400-600mM, 500-1000mM, 500-800mM, 500-600mM, 600-1000mM, 600-800mM, 700-1000mM, 700-800mM, 800-1000mM, or 800-900mM.

[0061] In some embodiments, in step S2, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium formate, sodium propionate, sodium butyrate, sodium benzoate, triethylamine, ethylenediamine, and urea; the molar ratio of the alkali to the organic ligand in the reaction solution B is (0.1-6):1.

[0062] In some embodiments, in step S3, the reaction temperature of the precipitation crystallization reaction is 5-90°C, for example, but not limited to, 5-80°C, 5-70°C, 5-60°C, 5-50°C, 5-40°C, 5-30°C, 5-20°C, 5-10°C, 15-90°C, 15-80°C, 15-70°C, 15-60°C, 15-50°C, 15-40°C, 15-30°C, 15-20°C, 25-90°C, 25-80°C, 25-70°C, 25-60°C. ℃, 25-50℃, 25-40℃, 25-30℃, 35-90℃, 35-80℃, 35-70℃, 35-60℃, 35-50℃, 35-40℃, 45-90℃, 45-80℃, 45-70℃, 45-60℃, 45-50℃, 55-90℃, 55-80℃, 55-70℃, 55-60℃, 65-90℃, 65-80℃, 65-70℃, 75-90℃, 75-80℃, or 85-90℃.

[0063] In some embodiments, in step S3, the volumetric flow rates of reaction solution A and reaction solution B injected into the hypergravity reactor via peristaltic pumps are both 50-600 mL / min, for example, but not limited to, 50-550 mL / min, 50-500 mL / min, 50-450 mL / min, 50-400 mL / min, 50-350 mL / min, 50-300 mL / min, 50-250 mL / min, 50-200 mL / min, 50-150 mL / min, 50-100 mL / min, 100-600 mL / min, 100-550 mL / min, 100

[0064] -500mL / min, 100-450mL / min, 100-400mL / min, 100-350mL / min, 100-300mL / min, 100-250mL / min, 100-200mL / min, 100-150mL / min, 150-600mL / min, 150-55 0mL / min, 150-500mL / min, 150-450mL / min, 150-400mL / min, 150-350mL / min, 150-300mL / min, 150-250mL / min, 150-200mL / min, 200-600mL / min, 200-550mL / min, 200-500mL / min, 200-450mL / min, 200-400mL / min, 200-350mL / min, 200-300mL / min, 200-250mL / min, 300-600mL / min, 300-550mL / min, 300-500mL / mi n, 300-450mL / min, 300-400mL / min, 300-350mL / min, 400-600mL / min, 400-550mL / min, 400-500mL / min, 400-450mL / min, 500-600mL / min, or 500-550mL / min.

[0065] In some embodiments, in step S3, the rotor speed of the external circulation rotary filling bed is 500-2850 rpm; more preferably, the rotor speed of the external circulation rotary filling bed is 500-2500 rpm.

[0066] In some embodiments, in step S4, the solvent used for washing and activation is one or more of deionized water, methanol, acetone, ethanol, N,N'-dimethylformamide, N,N'-dimethylacetamide, N,N'-diethylformamide, tetrahydrofuran, chloroform, and dichloromethane.

[0067] Preferably, in step S4, the washing and activation method involves continuously replacing the solvent 2-6 times.

[0068] In some embodiments, in step S4, the drying method is vacuum drying, and the drying temperature is 50-180℃, such as, but not limited to, 50-170℃, 50-160℃, 50-150℃, 50-140℃, 50-130℃, 50-120℃, 50-110℃, 50-100℃, 50-90℃, 50-80℃, and 50-70℃. 50-60℃, 70-180℃, 70-170℃, 70-160℃, 70-150℃, 70-140℃, 70-140℃, 70-130℃, 70-120℃, 70-110℃, 70-100℃, 70-90℃, 70-80℃, 90-180℃, 90-170℃, 90-160℃, 90-150℃, 90-1 40℃, 90-140℃, 90-130℃, 90-120℃, 90-110℃, 90-100℃, 110-180℃, 110-170℃, 110-160℃, 110-150℃, 110-140℃, 110-130℃, 110-120℃, 130-180℃, 130-170℃, 130-160℃, 130- 150℃, 130-140℃, 150-180℃, 150-170℃, 150-160℃; drying time 2-20h, for example but not limited to 2-17h, 2-14h, 2-11h, 2-8h, 2-5h, 5-20h, 5-17h, 5-14h, 5-11h, 5-8h, 8-20h, 8-17h, 8-14h, 8-11h.

[0069] Example 1

[0070] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0071] 1) Preparation of solution A: Dissolve 2.00 g (10.9 mmol) of anhydrous zinc acetate in 30 mL of deionized water by ultrasonic shaking at room temperature;

[0072] 2) Preparation of solution B: Dissolve 0.872 g (21.8 mmol) of sodium hydroxide in 30 mL of deionized water by ultrasonic vibration at room temperature; dissolve 1.08 g (5.45 mmol) of 2,5-dihydroxyterephthalic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature.

[0073] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and centrifuge all the product suspension to remove the supernatant.

[0074] 4) The centrifuged wet solid was first washed three times with deionized water, then washed three times with methanol. The cleaned wet solid was placed in a vacuum drying oven at 80°C for 12 hours. After the solvent evaporated, the MOF-74-Zn sample was obtained.

[0075] Figure 1 The product obtained in Example 1 is compared with the simulated XRD pattern of MOF-74-Zn material. The XRD pattern shows that the product is MOF-74-Zn particles with high crystallinity.

[0076] Figure 2 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 1. As can be seen from the image, the product particles are rod-shaped with a length range of about 5.5 μm, a narrow particle size distribution, and uniform particle size.

[0077] Example 2

[0078] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0079] 1) Preparation of solution A: Dissolve 2.80 g (10.9 mmol) of magnesium nitrate hexahydrate in 30 mL of deionized water by ultrasonic vibration at room temperature;

[0080] 2) Preparation of solution B: Dissolve 0.872 g (21.8 mmol) of sodium hydroxide in 30 mL of deionized water by ultrasonic vibration at room temperature; dissolve 1.08 g (5.45 mmol) of 2,5-dihydroxyterephthalic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature.

[0081] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and centrifuge all the product suspension to remove the supernatant.

[0082] 4) The centrifuged wet solid was first washed three times with deionized water, then washed three times with methanol. The cleaned wet solid was placed in a vacuum drying oven at 80°C for 12 hours. After the solvent evaporated, the MOF-74-Mg sample was obtained.

[0083] Figure 3 The product obtained in Example 2 is compared with the simulated XRD pattern of MOF-74-Mg material. The XRD pattern shows that the product is MOF-74-Mg particles with high crystallinity.

[0084] Figure 4 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 2. As can be seen from the image, the product particles are spherical with a size of about 1 μm, a narrow particle size distribution, and uniform particle size.

[0085] Example 3

[0086] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0087] 1) Preparation of solution A: Dissolve 1.74 g (7 mmol) of nickel acetate tetrahydrate in 100 mL of deionized water by ultrasonic shaking at room temperature;

[0088] 2) Preparation of solution B: Dissolve 0.56 g (14 mmol) of sodium hydroxide in 100 mL of deionized water by ultrasonic vibration at room temperature; dissolve 0.70 g (3.5 mmol) of 2,5-dihydroxyterephthalic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature.

[0089] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and centrifuge all the product suspension to remove the supernatant.

[0090] 4) The centrifuged wet solid was first washed three times with deionized water, then washed three times with methanol. The cleaned wet solid was placed in a vacuum drying oven at 80°C for 12 hours. After the solvent evaporated, the MOF-74-Ni sample was obtained.

[0091] Figure 5 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 3. As can be seen from the image, the product particles are spherical with a size of about 20 nm, a narrow particle size distribution, and uniform particle size.

[0092] Example 4

[0093] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0094] 1) Preparation of solution A: Dissolve 1.12 g (4.5 mmol) of cobalt acetate tetrahydrate in 100 mL of deionized water by ultrasonic shaking at room temperature;

[0095] 2) Preparation of solution B: Dissolve 0.36 g (9 mmol) of sodium hydroxide in 100 mL of deionized water by ultrasonic vibration at room temperature; dissolve 0.45 g (2.25 mmol) of 2,5-dihydroxyterephthalic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature.

[0096] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and centrifuge all the product suspension to remove the supernatant.

[0097] 4) The centrifuged wet solid was first washed three times with deionized water, then washed three times with methanol. The cleaned wet solid was placed in a vacuum drying oven at 80°C for 12 hours. After the solvent evaporated, the MOF-74-Co sample was obtained.

[0098] Figure 6 The image shows a transmission electron microscope (TEM) image of the product obtained in Example 4. As can be seen from the image, the particles of the obtained product are spherical with a particle size of about 150 nm, a narrow particle size distribution, and uniform particle size.

[0099] Example 5

[0100] 1) Preparation of solution A: Dissolve 0.362 g (1.5 mmol) of copper nitrate trihydrate in 100 mL of deionized water by ultrasonic shaking at room temperature;

[0101] 2) Preparation of solution B: Dissolve 0.12 g (3 mmol) of sodium hydroxide in 100 mL of deionized water by ultrasonic vibration at room temperature, and dissolve 0.21 g (1 mmol) of trimesic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature;

[0102] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and immediately centrifuge all the product suspension to remove the supernatant;

[0103] 4) The centrifuged wet solid was washed three times with ethanol. The cleaned wet solid was then placed in a vacuum drying oven at 70°C and dried for 12 hours. After the solvent evaporated, the sample HKUST-1 was obtained.

[0104] Figure 7 The product obtained in Example 5 is compared with the simulated XRD pattern of HKUST-1 material. The XRD pattern shows that the product is HKUST-1 particles with high crystallinity.

[0105] Figure 8 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 5. As can be seen from the image, the particles of the obtained product are spherical with a particle size of about 900 nm, a narrow particle size distribution, and uniform particle size.

[0106] Example 6

[0107] A method for continuous preparation of MOF materials in aqueous phase using high gravity technology includes the following steps:

[0108] 1) Preparation of solution A: Dissolve 2.00 g (10.9 mmol) of anhydrous zinc acetate in 30 mL of deionized water by ultrasonic shaking at room temperature, and add 300 μL of HOAc.

[0109] 2) Preparation of solution B: Dissolve 0.872 g (21.8 mmol) of sodium hydroxide in 30 mL of deionized water by ultrasonic vibration at room temperature; dissolve 1.08 g (5.45 mmol) of 2,5-dihydroxyterephthalic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature.

[0110] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and centrifuge all the product suspension to remove the supernatant.

[0111] 4) The centrifuged wet solid was first washed three times with deionized water, then washed three times with methanol. The cleaned wet solid was placed in a vacuum drying oven at 80°C for 12 hours. After the solvent evaporated, the MOF-74-Zn sample was obtained.

[0112] Figure 9 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 6. It can be seen from the image that the product particles are ellipsoidal in shape, with a length dimension of approximately 2.39 μm, a narrow particle size distribution, and uniform particle size. Combining Examples 1 and 6, it can be seen that adding a certain amount of acetic acid as a coordination competitive additive can effectively reduce the particle size.

[0113] Example 7

[0114] Repeat Example 6, except that: after reaction solution A and reaction solution B are prepared, they are cooled to 5°C in a cold water bath, and at the same time, the temperature of the external circulating rotating packed bed circulating water bath is set to 5°C, so that the reaction is carried out at 5°C. Figure 10 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 7. As can be seen from the image, the particles of the obtained product are spherical with a particle size of about 1.03 μm, a narrow particle size distribution, and uniform particle size.

[0115] from Figure 10 As can be seen, the product effect is similar to that of Example 6, but the average particle size is smaller, indicating that changing the temperature can control the particle size.

[0116] Example 8

[0117] 1) Prepare solution A: Dissolve 0.362 g (1.5 mmol) of copper nitrate trihydrate in 100 mL of deionized water by ultrasonic shaking at room temperature, and add 100 μL of HOAc.

[0118] 2) Preparation of solution B: Dissolve 0.12 g (3 mmol) of sodium hydroxide in 100 mL of deionized water by ultrasonic vibration at room temperature, and dissolve 0.21 g (1 mmol) of trimesic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature;

[0119] 3) Turn on the centrifugal reactor and adjust the rotor speed to 1500 rpm; simultaneously pump liquid A and liquid B into the centrifugal reactor to quickly and thoroughly mix and precipitate crystallize, controlling the feed rate on both sides to 100 mL / min. The reaction is carried out at room temperature. After both streams of material have been fed, turn off the centrifugal reactor. Collect the product suspension from the outlet of the external circulating rotating packed bed, and immediately centrifuge all the product suspension to remove the supernatant;

[0120] 4) The centrifuged wet solid was washed three times with ethanol. The cleaned wet solid was then placed in a vacuum drying oven at 70°C and dried for 12 hours. After the solvent evaporated, the sample HKUST-1 was obtained.

[0121] Figure 11 The image shows a scanning electron microscope (SEM) image of the product obtained in Example 8. As can be seen from the image, the particles of the obtained product are spherical with a particle size of about 480 nm, a narrow particle size distribution, and uniform particle size.

[0122] Example 9

[0123] Example 1 was repeated, except that the zinc salt was selected from one or more of zinc nitrate, zinc acetylacetonate, or zinc acetate dihydrate. The resulting product had similar effects to that of Example 1.

[0124] Example 10

[0125] Example 6 was repeated, except that the coordination competing additive used in reaction solution A was selected from one or more of formic acid, propionic acid, butyric acid, hydrofluoric acid, benzoic acid, citric acid, salicylic acid, hydrochloric acid, nitric acid, sulfuric acid, chloroacetic acid, and trifluoroacetic acid. The resulting product had similar effects to that of Example 6.

[0126] Example 11

[0127] Example 1 was repeated, except that the alkali source used in reaction solution B was selected from one or more of potassium hydroxide, ammonia, sodium acetate, sodium formate, sodium propionate, sodium butyrate, sodium benzoate, triethylamine, ethylenediamine, and urea. The resulting product had similar effects to that of Example 1.

[0128] Comparative Example 1

[0129] MOF-74-Zn was prepared using the steps described in Example 1, except that: Solution A was prepared by dissolving 0.26 g (1.45 mmol) of anhydrous zinc acetate in 200 mL of deionized water under ultrasonic vibration at room temperature;

[0130] Figure 12 The results of comparing the product obtained in Comparative Example 1 with the simulated XRD pattern of MOF-74-Zn material are as follows: MOF-74-Zn cannot be prepared by this method. Comparing the obtained product with the simulated XRD pattern of MOF-74-Zn material, it can be seen from the XRD pattern that the product is an amorphous product. This is because the concentration of metal salt is too low to precipitate and crystallize.

[0131] Comparative Example 2

[0132] MOF-74-Zn was prepared using the steps described in Example 6, with the following difference: Step 1) Preparation of Solution A: 2.00 g (10.9 mmol) of anhydrous zinc acetate was dissolved in 30 mL of deionized water by ultrasonic vibration at room temperature, and 500 μL of HOAc was added. The results are as follows: MOF-74-Zn could not be prepared by this method. Comparing the obtained product with the simulated XRD pattern of MOF-74-Zn material, it can be seen from the XRD pattern that the product contains a large amount of the reactant 2,5-dihydroxyterephthalic acid. This is because the additive is excessive and acidic, and the ligand cannot be deprotonated and combine with the metal salt, thus failing to precipitate and crystallize into MOF-74-Zn.

[0133] Comparative Example 3

[0134] 1) Preparation of solution A: Dissolve 0.362 g (1.5 mmol) of copper nitrate trihydrate in 100 mL of deionized water by ultrasonic shaking at room temperature, and add 100 μL of glacial acetic acid to the solution.

[0135] 2) Preparation of solution B: Dissolve 0.12 g (3 mmol) of sodium hydroxide in 100 mL of deionized water by ultrasonic vibration at room temperature, and dissolve 0.21 g (1 mmol) of trimesic acid in the above sodium hydroxide solution by ultrasonic vibration at room temperature;

[0136] 3) At room temperature, place a 400mL beaker on a magnetic stirrer, place the magnetic stir bar, adjust the speed to 500rpm, pour liquid A and liquid B into the beaker at the same time to react. After the two materials are mixed, turn off the magnetic stirrer, collect the product suspension, and immediately centrifuge all the product suspension to remove the supernatant.

[0137] 4) The centrifuged wet solid was washed three times with ethanol. The cleaned wet solid was then placed in a vacuum drying oven at 70°C and dried for 12 hours. After the solvent evaporated, the sample HKUST-1 was obtained.

[0138] Figure 13 The image shown is a scanning electron microscope image of the product obtained in Comparative Example 3. The product consists of rod-shaped particles with a size of tens of micrometers and uneven size distribution. Because the mixing of the reaction solution by magnetic stirring in the beaker is less uniform and complete compared to the supergravity reactor, a rapid and large-scale nucleation process cannot occur. Therefore, the product obtained in the beaker has uneven particle size and a very large particle size.

[0139] Comparative Example 4

[0140] MOF-74-Zn was prepared using the steps described in Example 1, with the difference that in step S2, Chinese Patent Publication No. CN112341630A, entitled "Method for Continuous Preparation of Nanoscale Metal-Organic Framework Materials Using Hypergravity Technology," was used. The organic ligands were directly dissolved in deionized water instead of in sodium hydroxide solution. The result was that pure MOF-74-Zn could not be prepared, and the obtained product contained a large amount of unreacted organic ligands that could not be separated. This is because the organic ligands are insoluble in water at room temperature, preventing the reaction from proceeding.

[0141] Comparative Example 5

[0142] MOF-74-Zn was prepared using the steps described in Example 1, with the difference that steps S1 and S2 used the method of Chinese Patent Publication No. CN114891233A, entitled "Preparation of Nano-Zirconium-based MOFs Using an Internal Circulation Rotary Packed Bed". The specific steps are as follows: zinc metal salt and organic ligand solid were weighed, and deionized water was added. No alkali source was added to the system, and the reaction was carried out at room temperature. The result was that pure MOF-74-Zn could not be prepared. The obtained product contained a large amount of unreacted organic ligands, which could not be separated. This is because the organic ligands are insoluble in water, and at room temperature, the organic ligands cannot deprotonate and form coordination bonds with metal ions, thus preventing the reaction from proceeding.

[0143] Comparative Example 6

[0144] MOF materials were prepared using the steps described in Example 1, except that lead acetate, which is not within the range of metal salts selected in step S1, was used in step 1). The result was that the corresponding lead-based MOF materials could not be formed.

[0145] Comparative Example 7

[0146] MOF-74-Zn was prepared using the steps described in Example 1, except that: Step 1) Preparation of solution B: 10.8 g (54.5 mmol) of 2,5-dihydroxyterephthalic acid was dissolved in 30 mL of deionized water under ultrasonic vibration at room temperature. The result was as follows: the ligand concentration was too high and could not be completely dissolved, so a pure MOF-74-Zn product could not be obtained.

[0147] Comparative Example 8

[0148] MOF-74-Zn was prepared using the steps described in Example 6, with the following difference: Step 1) Preparation of Solution A: 2.00 g (10.9 mmol) of anhydrous zinc acetate was dissolved in 30 mL of deionized water by ultrasonic oscillation at room temperature, and 300 μL of boric acid, which is not within the range of coordination competing additives selected in step S1, was added. The result was as follows: MOF-74-Zn could not be prepared by this method.

[0149] Comparative Example 9

[0150] MOF-74-Zn was prepared using the steps described in Example 1, except that the reaction in step 3) was carried out at 95°C. The result was as follows: the size distribution of the formed MOF-74-Zn material was uneven. This was because the reaction temperature was close to the boiling point of the solvent, the solvent evaporated in large quantities, the precursor concentration changed significantly in a short time, and the nucleation and growth were uneven.

[0151] Comparative Example 10

[0152] MOF-74-Zn was prepared using the steps described in Example 1, except that in step 3), the feed volume flow rate of the peristaltic pumps on both sides was 20 mL / min. The result was as follows: the size distribution of the formed MOF-74-Zn material was uneven. The reason was that the feed flow rate was too small and the initial velocity of the liquid at the feed inlet was low. The two reactants could not be premixed at the feed inlet, which affected the mass transfer process and caused uneven particle size distribution.

[0153] Comparative Example 11

[0154] MOF-74-Zn was prepared using the steps described in Example 1, except that in step 4), the cleaned wet solid was placed in a vacuum drying oven at 40°C for 12 hours. The result was as follows: MOF-74-Zn powder could not be obtained because the drying temperature was too low.

[0155] Comparative Example 12

[0156] MOF-74-Zn was prepared using the steps described in Example 1, except that in step 4), the cleaned wet solid was placed in a vacuum drying oven at 80°C for 1.5 hours. The result was that MOF-74-Zn powder could not be obtained because the drying time was too short.

[0157] In summary, the preparation method of the present invention, including the selection of raw materials and the selection of various parameters, constitutes an overall technical solution. Only through mutual cooperation can the metal-organic framework material of the present invention be obtained; any deviation from the conditions will result in the failure to achieve the purpose of the present invention.

[0158] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for continuous preparation of MOF materials in aqueous phase using high gravity technology, characterized in that, Includes the following steps: S1. Weigh out a metal salt and dissolve it in a deionized aqueous solution at room temperature, and record it as reaction solution A; S2. Weigh out the organic ligand and dissolve it in an alkaline solution at room temperature, and record it as reaction solution B; S3. Turn on the hypergravity reactor and simultaneously introduce reaction solution A and reaction solution B into the hypergravity reactor by a peristaltic pump to carry out precipitation and crystallization reaction. A MOF material suspension was prepared; the high-gravity reactor was selected from an external circulation rotating packed bed reactor. S4. Centrifuge, wash, activate, and dry the suspension to obtain MOF products; In step S1, the metal salt is selected from one or more of the following soluble salts: zinc salt, magnesium salt, cobalt salt, nickel salt, aluminum salt, manganese salt, iron salt, copper salt, and cadmium salt. In step S1, the concentration of the metal salt in the reaction solution A is 10-1000 mM; In step S1, a coordination competition additive is further added to the reaction solution A. The coordination competition additive is selected from one or more of formic acid, acetic acid, propionic acid, n-butyric acid, hydrofluoric acid, benzoic acid, citric acid, salicylic acid, hydrochloric acid, nitric acid, sulfuric acid, chloroacetic acid, and trifluoroacetic acid. In step S1, the molar ratio of the coordination competing additive to the metal salt is (0-1.5):1; In step S2, the organic ligand is selected from one or more of 2,5-dihydroxyterephthalic acid, pyromellitic acid, terephthalic acid, 2-aminopyromellitic acid, 2-aminoterephthalic acid, 2-hydroxyterephthalic acid, 2,5-diaminoterephthalic acid, 4,4'-biphenyl dicarboxylic acid, 3,3'-dihydroxy-4,4'-biphenyl dicarboxylic acid, fumaric acid, and 2,5-thiophene dicarboxylic acid; In step S2, the concentration of the organic ligand solution is 10-1000 mM; In step S2, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium formate, sodium propionate, sodium butyrate, sodium benzoate, triethylamine, ethylenediamine, and urea; the molar ratio of the alkali to the organic ligand in the reaction solution B is (0.1-6):

1. In step S3, the reaction temperature of the precipitation crystallization reaction is 5-90℃; In step S3, the volumetric flow rates of reaction solution A and reaction solution B injected into the hypergravity reactor by a peristaltic pump are both 50-600 mL / min. In step S3, the rotor speed of the external circulation rotary filling bed is 500-2850 rpm; In step S4, the solvent used for washing and activation is one or more of deionized water, methanol, acetone, ethanol, N,N'-dimethylformamide, N,N'-dimethylacetamide, N,N'-diethylformamide, tetrahydrofuran, chloroform, and dichloromethane. In step S4, the washing and activation method involves continuously replacing the solvent 2-6 times. In step S4, the drying method is vacuum drying, the drying temperature is 50-180℃, and the drying time is 2-20h.

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