Submicron UiO-66 material and synthesis method thereof

Abstract

The invention is applicable to the technical field of chemical materials, and provides a submicron UiO-66 material and a synthetic method thereof, the synthetic method comprises the following steps: step 1, adding zirconium tetrachloride and terephthalic acid into an N, N-dimethylformamide solution, and carrying out ultrasonic treatment; step 2, adding glacial acetic acid into the solution obtained in the step 1, and carrying out ultrasonic treatment; 3, putting the solution obtained in the step 2 into a reaction kettle, and keeping at 120 DEG C for 24 hours; and 4, cooling to room temperature, centrifugally washing the product obtained in the step 3, and drying in vacuum to obtain the UiO-66 material. The glacial acetic acid is used as a regulator, synthesis of the UiO-66 material is accurately regulated and controlled, the crystallinity of the material is improved, and uniform growth of crystals is promoted. By optimizing the relative proportion of glacial acetic acid to the solvent, the crystal size is successfully controlled at the submicron level, and the synthesized UiO-66 material has wide application prospects in the aspect of active substance loading.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical materials, and in particular relates to a submicron UiO-66 material and a synthesis method thereof. Background Art

[0002] UiO-66 (UiO = University of Oslo) is a metal organic framework material with zirconium ions as metal centers and terephthalic acid as organic ligands, and has a periodic structure. In recent years, with its excellent chemical stability, high specific surface area and high porosity, UiO-66 has shown broad application prospects in gas adsorption and separation, catalytic sensing, drug loading and delivery, etc.

[0003] In terms of synthesis methods, compared with microwave-assisted and electrochemical methods, which have high equipment requirements and cumbersome operations, the solvothermal method has become a common method for synthesizing UiO-66 due to its simple process and low cost. The specific preparation steps are to dissolve the zirconium source and terephthalic acid in N,N-dimethylformamide solution to form a mother liquor, and transfer it to a stainless steel autoclave. At a certain crystallization temperature and time, zirconium ions and terephthalic acid self-assemble to form UiO-66 crystals. However, during the synthesis process, uneven coordination is prone to occur between the metal center and the organic ligand, resulting in low crystallinity of the generated crystals. In addition, the method of controlling crystal growth by regulating the solvent volume is difficult to operate accurately, which may result in irregular morphology and a wide size distribution of the generated crystals, thereby affecting the stability of the overall performance of the material.

[0004] Introducing a regulator is an effective improvement method. Existing studies have used organic acids as regulators to effectively improve the crystallinity of Zr-MOF and have controlled the crystal particle size to a certain extent by changing the dosage of the regulator (A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke, P. Behrens, Modulated Synthesis of Zr-Based Metal–Organic Frameworks: From Nano to Single Crystals, Chemistry–A European Journal 17(24)(2011)6643-6651; K. C. Bentz, S. Ayala, M. Kalaj, S. M. Cohen, Polyacids as Modulators for the Synthesis of UiO-66, Australian Journal of Chemistry 72(10)(2019)848-851). However, the efficiency of controlling the particle size uniformity only by the regulator content is low, and the influence of N,N-dimethylformamide on the crystal particle size is ignored. As a solvent, N,N-dimethylformamide can, on the one hand, fully dissolve the raw materials, and on the other hand, its own polarity can enhance the role of the regulator, thereby further stabilizing the crystal growth process and better controlling the crystal size. Currently, there are few studies on crystal synthesis by controlling the relative ratio of the regulator to the solvent, and further exploration and technical optimization are still needed. For this reason, the present invention proposes a submicron-sized UiO-66 material and its synthesis method. Summary of the Invention

[0005] The purpose of the present invention is to provide a submicron-sized UiO-66 material and its synthesis method, aiming to solve the problems raised in the above background technology.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A synthesis method of a submicron-sized UiO-66 material, comprising the following steps:

[0008] Step 1: Add zirconium tetrachloride and terephthalic acid to an N,N-dimethylformamide solution and perform ultrasonic treatment;

[0009] Step 2: Add glacial acetic acid to the solution obtained in Step 1 and perform ultrasonic treatment;

[0010] Step 3: Put the solution obtained in Step 2 into a reaction kettle and keep it at 120 °C for 24 h;

[0011] Step 4: After cooling to room temperature, the product obtained in Step 3 is centrifuged, washed, and dried under vacuum to obtain UiO-66 material;

[0012] In the said Step 4, the washing solution is N,N-dimethylformamide, and the volume ratio of the N,N-dimethylformamide solution to glacial acetic acid is (1250 - 12500):(112.5 - 1703).

[0013] Furthermore, in the said Step 1, the molar ratio of zirconium tetrachloride to terephthalic acid is 1:1.

[0014] Furthermore, in the said Step 1, the time of ultrasonic treatment is 10 - 20 min, and more preferably 10 min.

[0015] Furthermore, in the said Step 2, the time of ultrasonic treatment is 5 - 20 min. More preferably 10 min.

[0016] Furthermore, in the said Step 4, the centrifugation speed is 8000 - 9000 rpm, the centrifugation time is 5 - 8 min, the drying temperature is 60 - 80 °C, and the drying time is 12 - 24 h.

[0017] Furthermore, the volume ratio of the N,N-dimethylformamide solution to glacial acetic acid is 11350:1703.

[0018] A submicron-sized UiO-66 material prepared by the synthesis method described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The method provided by the present invention uses glacial acetic acid as a regulator to precisely control the synthesis of UiO-66 material, which not only improves the crystallinity of the material but also promotes the uniform growth of crystals. By further optimizing the relative ratio of glacial acetic acid to the solvent, the crystal size is successfully controlled at the submicron level. This optimization strategy not only solves the problems of irregularity and non-uniformity existing in the traditional synthesis of UiO-66 material but also significantly improves the loading capacity of the material for active substances. The synthesized UiO-66 material has broad application prospects in the loading of active substances. Description of the Drawings

[0021] Figure 1 Scanning electron microscope images of the samples in Examples 1 - 4; where a is the scanning electron microscope image of the sample in Example 1, b is the scanning electron microscope image of the sample in Example 2, c is the scanning electron microscope image of the sample in Example 3, and d is the scanning electron microscope image of the sample in Example 4.

[0022] Figure 2 X-ray diffraction experimental diagram of the sample in Example 4.

[0023] Figure 3 It is the Fourier transform infrared spectrum of the sample of Example 4.

[0024] Figure 4 It is the schematic diagram of the dynamic light scattering distribution of the sample of Example 4.

[0025] Figure 5 It is the related characterization diagram of the samples of Examples 1-4 loaded with methyl red dye; where a is the ultraviolet absorption curve of methyl red-ethanol solutions with different concentrations, b is the standard ultraviolet absorption curve (494nm) of methyl red-ethanol solution, c is the ultraviolet absorption curve of the solution prepared by loading methyl red on the samples of Examples 1-4, and d is the loading rate of the samples of Examples 1-4. Detailed implementation manners

[0026] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0027] The following describes the specific implementation of the present invention in detail with reference to specific embodiments.

[0028] Example 1: Weigh 26.5 mg of zirconium tetrachloride and 19 mg of terephthalic acid and mix them in 1.25 mL of N,N-dimethylformamide solution, and ultrasonicate for 10 min; pour 112.5 μL of glacial acetic acid into the above mixed solution and ultrasonicate again for 10 min; transfer the obtained solution to a 22.5 mL reaction kettle and maintain it at 120 °C for 24 h; after the reaction is completed, cool it to room temperature, centrifuge the obtained product solution at 8000 rpm for 5 min, and wash it with N,N-dimethylformamide solution; finally, vacuum-dry the centrifuged product at 60 °C for 24 h.

[0029] Example 2: The same as Example 1, the amount of glacial acetic acid is 150 μL, 2.5 mL of N,N-dimethylformamide solution is used as the reaction solution, and other conditions remain unchanged.

[0030] Example 3: The same as Example 1, the amount of glacial acetic acid is 1125 μL, 12.5 mL of N,N-dimethylformamide solution is used as the reaction solution, and other conditions remain unchanged.

[0031] Example 4: The same as Example 1, the amount of glacial acetic acid is 1703 μL, 11.35 mL of N,N-dimethylformamide solution is used as the reaction solution, and other conditions remain unchanged.

[0032] Methyl red loading experiment: Accurately weigh 5 mg of the samples of Examples 1 to 4 and place them in a centrifuge tube. Add 2 mL of methyl red ethanol (10 μg / mL) solution, shake well to disperse, and then place it in a vacuum oven. Keep it under the maximum negative pressure condition for 5 min, and repeat the dispersion and negative pressure treatment 3 times to ensure that the sample reaches the maximum loading amount. Subsequently, centrifuge at 8000 rpm, take the supernatant of the solution, dilute it to 3 mL to obtain a free methyl red solution, and conduct ultraviolet-visible absorption tests on it. Combine with the concentration-absorbance standard curve of the methyl red-ethanol solution, and use the formula: [(content of original methyl red - content of free methyl red) / content of original methyl red]×100%, to calculate the loading rate of the samples of Examples 1 to 4 for methyl red.

[0033] Material characterization:

[0034] 1. Morphology characterization: Use a cold field scanning electron microscope produced by Hitachi, Ltd., Japan to observe and characterize the morphology of the samples of Examples 1 to 4. As can be seen from Figure 1 a - d, from Example 1 to Example 4, the octahedral morphology of the sample becomes gradually significant, indicating that glacial acetic acid effectively promotes the regular growth of crystals.

[0035] 2. Crystallization property and chemical property characterization: Use an X-ray diffractometer produced by Bruker Corporation, Germany and a Fourier transform infrared spectrometer produced by Thermo Fisher Scientific, Inc., USA to characterize the crystallization property and chemical property of the sample of Example 4. As can be seen from Figure 2 it that the positions of the diffraction peaks of the sample coincide with the standard peak positions, confirming that the material is UiO-66; at the same time, the corresponding diffraction peaks are sharp and have high intensity, indicating that the sample has high crystallinity. As can be seen from Figure 3 it that there are vibration peaks of μ3-OH, Zr(O-C), μ3-O, O-Zr-O vibration peak, C=C vibration peak on the aromatic ring, and related vibration peaks of carboxyl groups in the sample, further confirming that the sample has the characteristic functional groups of UiO-66.

[0036] 3. Particle size analysis: Use a nano particle size analyzer produced by Malvern Instruments Ltd., UK to analyze the particle size of the sample of Example 4. As can be seen from Figure 4 it that the PDI index of the sample is less than 0.2, indicating that the particle size distribution is uniform, the consistency of the particle size is good, and the average size is 912.30 nm, which is in the submicron range.

[0037] 4. Loading rate characterization: Use an ultraviolet-visible spectrophotometer to characterize the loading rate of the samples of Examples 1 to 4. As can be seen from Figure 5 a that the maximum absorption peak of methyl red in the ethanol solution appears at 494 nm, and as the concentration of methyl red increases, the absorbance gradually increases. Therefore, a concentration-absorbance standard curve can be established here.Figure 5 As can be seen from b, the variance of the established standard curve is 0.9998, which is very close to 1, indicating that the curve has a strong linear relationship. The relational expression can be used for subsequent calculations. From Figure 5 As can be seen from c and d, the content of free methyl red corresponding to the sample of Example 4 is the lowest, so the loading rate is the highest, reaching 48.61%.

[0038] The above are only the preferred embodiments of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent.

Claims

1. A method for synthesizing submicron UiO-66 material, characterized in that: The steps include: Step 1: adding zirconium tetrachloride and terephthalic acid into N,N-dimethylformamide solution and performing ultrasonic treatment; Step 2: adding glacial acetic acid to the solution obtained in step 1 and performing ultrasonic treatment; Step 3: Place the solution obtained in step 2 into a reaction kettle and keep it at 120°C for 24 hours; Step 4: After cooling to room temperature, the product obtained in step 3 is centrifuged, washed, and vacuum dried to obtain UiO-66 material; In step 4, the washing solution is N,N-dimethylformamide, and the volume ratio of N,N-dimethylformamide solution to glacial acetic acid is (1250-12500):(112.5-1703).

2. The synthesis method according to claim 1, characterized in that In the step 1, the molar ratio of zirconium tetrachloride to terephthalic acid is 1:

1.

3. The synthesis method according to claim 1, characterized in that In the step 1, the ultrasonic treatment time is 10 to 20 minutes.

4. The synthesis method according to claim 3, characterized in that The ultrasonic treatment time is 10 min.

5. The synthesis method according to claim 1, characterized in that In the step 2, the ultrasonic treatment time is 5 to 20 minutes.

6. The synthesis method according to claim 5, characterized in that The ultrasonic treatment time is 10 min.

7. The synthesis method according to claim 1, characterized in that In step 4, the centrifugal speed is 8000-9000 rpm, the centrifugal time is 5-8 min, the drying temperature is 60-80° C., and the drying time is 12-24 h.

8. The synthesis method according to claim 1, characterized in that The volume ratio of the N,N-dimethylformamide solution to glacial acetic acid is 11350:1703.

9. A submicron UiO-66 material obtained according to the synthesis method according to any one of claims 1 to 8.

Images