Mof-808 material based on zirconium acetylacetonate, its microwave preparation method and application in catalytic degradation of deppt

Abstract

The application provides a MOF-808 material based on zirconium acetylacetonate, a microwave preparation method of the MOF-808 material and application of the MOF-808 material in catalytic degradation of DEPPT, the MOF-808 material is based on zirconium acetylacetonate as a zirconium source, the MOF-808 material has rich Zr-OH active sites, and a Fourier infrared spectrum of the MOF-808 material has a Zr-OH characteristic absorption peak near 3670 cm ‑1 In addition, the MOF-808 material also comprises titanium elements. The application provides a metal zirconium source more suitable for a microwave synthesis system, so as to optimize a reaction process and realize precise regulation of a material structure, improve the catalytic degradation performance of a single zirconium-based MOF-808 on DEPPT, and develop a simple "one-pot" process to realize in-situ introduction of heterogeneous metal ions with a synergistic catalytic effect in the MOF-808 crystal to construct multifunctional active sites, and the catalytic degradation efficiency of the MOF-808 on a nerve agent simulant DEPPT is improved by 50% compared with the MOF-808 without doped metal, and the MOF-808 has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal-organic framework material synthesis technology, and relates to a MOF-808 material based on zirconium acetylacetonate, its microwave preparation method, and its application in the catalytic degradation of DEPPT. Technical Background

[0002] Nerve agents (such as sarin, soman, and VX) possess extremely high toxicity and rapid-acting capabilities, posing a serious threat to public safety and national defense. In practical training, testing, and safety assessments, less toxic mimics, such as diethyl phosphate-p-nitrophenol (DEPPT), are often used to replace real agents in research. Therefore, developing novel materials capable of efficiently and rapidly catalytically degrading such mimics is of great significance for the development of chemical protection technologies.

[0003] Metal-organic frameworks (MOFs) are a class of crystalline porous materials formed by the self-assembly of metal ions or clusters with organic ligands. Due to their ultra-high specific surface area, tunable pore size, and abundant active sites, they exhibit great potential in catalysis, adsorption, and separation. Among them, MOF-808, with zirconium clusters as nodes, is considered a highly promising material for the catalytic degradation of chemical agents due to its excellent hydrothermal stability, abundant coordinated unsaturated zirconium sites, and strong affinity for phosphate ester molecules (typical structures of nerve agents and their analogues).

[0004] Currently, the synthesis of MOF-808 mainly employs a conventional solvothermal method, using inorganic zirconium salts (such as zirconium oxychloride octahydrate, ZrOCl2·8H2O) as the metal source and trimesic acid (BTC) as the ligand, reacting at high temperatures for an extended period. However, this method generally suffers from drawbacks such as long reaction times (typically requiring 24-48 hours), high energy consumption, and difficulty in precisely controlling crystal size and morphology. In recent years, microwave synthesis has been introduced into the preparation of MOF materials. By directly applying microwave radiation to the reaction molecules, it enables rapid and uniform heating of the reaction system, significantly shortening the reaction time to tens of minutes or even minutes, and holds promise for obtaining smaller and more uniform crystals. Nevertheless, existing research on the microwave synthesis of MOF-808 still largely uses traditional inorganic zirconium salts as the metal source. However, inorganic zirconium salts exhibit rapid dissociation rates and vigorous nucleation behavior in solution, resulting in poor controllability of structural defects in the formed Zr6 clusters, making it difficult to obtain high-density, uniformly distributed Zr-OH active sites after removing the modifier. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention aims to provide a zirconium acetylacetonate-based MOF-808 material, its microwave preparation method, and its application in the catalytic degradation of DEPPT. Specifically, it overcomes the drawbacks of long reaction cycles and high energy consumption in the traditional solvothermal synthesis of MOF-808; provides a zirconium metal source more suitable for microwave synthesis systems to optimize the reaction process and achieve precise control of the material structure; enhances the catalytic degradation performance of single zirconium-based MOF-808 for DEPPT; and develops a simple one-pot process to introduce heterogeneous metal ions with synergistic catalytic effects in situ into MOF-808 crystals to construct multifunctional active sites.

[0006] The technical solution of the present invention is as follows: A zirconium acetylacetonate-based MOF-808 material, wherein the zirconium source includes zirconium acetylacetonate, the MOF-808 material has abundant Zr-OH active sites, and its Fourier transform infrared spectrum is at 3670 cm⁻¹. -1 There are characteristic absorption peaks of Zr-OH in the vicinity.

[0007] The MOF-808 material also includes titanium, wherein the molar ratio of titanium to zirconium is 96:4 to 99.5:0.5.

[0008] The zirconium source also includes an inorganic zirconium source, which includes one or more of zirconium oxychloride octahydrate, zirconium chloride, zirconium hydroxide, and zirconium-oxygen clusters.

[0009] The molar ratio of zirconium acetylacetonate to inorganic zirconium source is 2:8~0.5:9.5.

[0010] The present invention also provides a method for preparing the above-mentioned MOF-808 material, wherein a zirconium source, pyromellitic acid, formic acid and N,N-dimethylformamide are mixed to form a mixed solution, and the material is synthesized in one step by microwave radiation reaction.

[0011] The microwave reaction temperature is 30~150℃, and the reaction time is 10~90min. Further, the microwave reaction temperature is 50~120℃, and the reaction time is 15-70min. Even further, the microwave reaction temperature is 70~110℃, and the reaction time is 30-60min.

[0012] The microwave radiation is single-mode microwave radiation.

[0013] The mixed solution also includes a doped metal source, which is a titanium source. The titanium source is tetraisopropyl titanate.

[0014] The volume ratio of formic acid to N,N-dimethylformamide is 90:10 to 30:70. Further, the volume ratio of formic acid to N,N-dimethylformamide is 60:40 to 40:60.

[0015] The molar volume ratio of zirconium acetylacetonate to DMF is 1 mmol : (2~14) mL.

[0016] It also includes washing and drying after the reaction.

[0017] The drying temperature is 80-120℃, and the drying time is 12-24h.

[0018] The drying process is vacuum drying.

[0019] The present invention also provides an application of the above-mentioned MOF-808 material in the catalytic degradation of DEPPT.

[0020] This invention offers the following advantages: The zirconium source comprises zirconium acetylacetonate, and MOF-808 material is synthesized using a microwave reactor, significantly improving synthesis efficiency. The reaction time is shortened by approximately 24 times compared to the traditional solvothermal method, and the resulting MOF-808 material possesses abundant Zr-OH active sites. By introducing a titanium source, the number of active sites in the material is significantly increased, resulting in a 50% improvement in its catalytic degradation efficiency against the nerve agent mimic DEPPT compared to undoped MOF-808. Attached Figure Description

[0021] Figure 1 The images show the SEM image and EDS spectrum of MOF-808-zirconium acetylacetonate from Example 1, as well as the EDS mapping image (magnification of 5000x).

[0022] Figure 2 Fourier transform infrared spectra of MOF-808-zirconium acetylacetonate in Example 1, MOF-808-zirconium oxychloride octahydrate in Example 2, and MOF-808-Ti in Example 12.

[0023] Figure 3 The images shown are SEM images and EDS spectra of MOF-808-Ti from Example 12, as well as the EDS mapping image (magnification of 5000x).

[0024] Figure 4 This is a schematic diagram of the testing process. Detailed Implementation

[0025] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0026] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0027] The specific test procedure for the catalytic degradation of DEPPT is as follows: First, 2.5 mg of the catalyst obtained in the example and 9.9 mg of DTNB as a colorimetric reagent were placed in a glass bottle. Then, 1 ml of NEM aqueous solution of a certain concentration was added, and the solution was ultrasonically cleaned for 20 min to disperse the catalyst as much as possible. Next, a stir bar was added, and the solution was immediately placed on a magnetic stirrer and stirred at 1500 rpm. 10 μL of the reaction solution was taken out and injected into 3 ml of NEM for dilution. The solution was then dispersed in an adjustable mixer for 10 s, and immediately poured into a cuvette for detection using a UV spectrophotometer. Simultaneously, 5.6 μL of DEPPT was added to the reaction solution. At 1, 3, 5, 7, 10, 15, 30, 45, 60, and 90 min after addition, 10 μL of the reaction solution was taken out, diluted, and tested. The test procedure is attached. Figure 4 .

[0028] Example 1 Preparation of MOF-808-zirconium acetylacetonate Acetylacetone and trimesic acid ligand were mixed in a molar ratio of 3:1 in a mixture of 15 ml formic acid and 15 ml N,N-dimethylformamide to obtain a mixed solution. The solution was dissolved by sonication for 60 min and then reacted in a single-mode microwave reactor at 70 °C for 60 min. The resulting product was washed five times by centrifugation with DMF or anhydrous ethanol at 10000 rpm for 30 min each time. After vacuum drying at 100 °C for 24 h, MOF-808-zirconium acetylacetone powder was obtained. The SEM image of this powder is shown below. Figure 1 As shown, MOF-808 exhibits a relatively regular hexagonal bipyramidal shape.

[0029] Examples 2-9 The experimental method of Example 1 was followed, but the difference from Example 1 was that the zirconium sources were zirconium oxychloride octahydrate, zirconium chloride, zirconium hydroxide, zirconium oxide clusters, zirconium acetylacetonate with zirconium oxychloride octahydrate, zirconium acetylacetonate with zirconium chloride, zirconium acetylacetonate with zirconium hydroxide, and zirconium acetylacetonate with zirconium oxide clusters. The half-life and 30-minute equilibrium degradation rate of the prepared MOF-808 are shown in Table 1. It can be seen that the MOF-808 synthesized using zirconium acetylacetonate as the metal source has significantly better performance. Figure 2 The RT-IR spectrum shows that the RT-IF spectrum of the MOF-808-zirconium acetylacetonate sample is at 3670 cm⁻¹. -1The sample synthesized using zirconium oxychloride octahydrate exhibits a distinct Zr-OH / H2O characteristic peak, while no such peak is observed. This difference is attributed to the varying behavior of ligands in different metal source precursors under the same synthetic conditions. In zirconium acetylacetone, the acetylacetone ligand binds to Zr via a bidentate chelate structure. 4+ The coordination complex, possessing strong bond energies, is only partially removed under solvothermal conditions. This partially removed coordination environment provides coordination unsaturation for the Zr-OH / H2O active center, favoring the formation of Zr-OH / H2O. In contrast, the Zr in the zirconium oxychloride octahydrate precursor... 4+ The coordination interaction with ligands is relatively weak, and it is easily completely replaced by solvent molecules or regulators during solvothermal processes. However, after substitution, the coordination sites are quickly occupied by acid regulators or BTC ligands, which limits the formation of Zr-OH / H2O. This is precisely why MOF-808 synthesized using zirconium acetylacetonate as the metal source exhibits better performance.

[0030] Table 1. Properties of MOF-808 prepared with different metallic zirconium sources

[0031] Examples 10-14 The experimental method of Example 1 was followed, but the difference from Example 1 was that the mixed solution also included tetraisopropyl titanate, and the molar ratio of zirconium acetylacetonate to tetraisopropyl titanate was changed. The half-life and 30-minute equilibrium degradation rate of the prepared MOF-808 are shown in Table 2. Figure 1 and Figure 3 As shown, doping with Ti in MOF-808 did not affect its morphology. Furthermore, the mapping image confirms that Ti was successfully incorporated into MOF-808. Figure 2 The infrared spectrum shows that it is located at approximately 3670 cm⁻¹ -1 The Zr-OH / H2O stretching vibration peak at approximately 1050 cm⁻¹ weakens, while the peak at approximately 1050 cm⁻¹ also weakens. -1 A new characteristic peak appeared. This peak can be attributed to the bending vibration of Ti-OH or the stretching vibration of the Zr-O-Ti bridging structure. This change indicates that Ti... 4+ Ions have been successfully incorporated in situ into the Zr6O4(OH)4 metal cluster of MOF-808, forming a Zr-O-Ti heterometallic bridging structure, and possibly accompanied by the generation of Ti-OH or novel activated μ3-OH groups. These structural units induced by Ti doping collectively constitute a "new active center" distinct from the original MOF-808, providing additional or more efficient sites for catalytic reactions.

[0032] Table 2. Performance of MOF-808-Ti doped with different amounts of tetraisopropyl titanate.

[0033] Examples 15-18 The experimental method of Example 1 was followed, but the volume ratio of formic acid and the reaction solvent N,N-dimethylformamide was changed. The half-life and 30-minute equilibrium degradation rate of the prepared MOF-808 are shown in Table 3.

[0034] Table 3. Performance of MOF-808 with different formic acid to solvent ratios.

[0035] Examples 19-22 The experimental method of Example 1 was followed, but the temperature of the single-mode microwave reaction was changed. The half-life and 30-minute equilibrium degradation rate of the prepared MOF-808 are shown in Table 4. The reaction temperature was 80-100℃, and the reaction time was 30-60 min.

[0036] Table 4 Performance of MOF-808 at different reaction times

[0037] Examples 23-26 The experimental method of Example 1 was followed, but the difference from Example 1 was that the single-mode microwave reaction time was changed. The half-life and 30-minute equilibrium degradation rate of the prepared MOF-808 are shown in Table 5.

[0038] Table 5

Claims

1. A MOF-808 material based on zirconium acetylacetonate, characterized in that: The zirconium source includes zirconium acetylacetone. The MOF-808 material has abundant Zr-OH active sites, and its Fourier transform infrared spectrum is at 3670 cm⁻¹. -1 There are characteristic absorption peaks of Zr-OH in the vicinity.

2. The MOF-808 material based on zirconium acetylacetonate as described in claim 1, characterized in that: The MOF-808 material also includes titanium, wherein the molar ratio of titanium to zirconium is 96:4 to 99.5:0.

5.

3. The MOF-808 material based on zirconium acetylacetonate as described in claim 1, characterized in that: The zirconium source also includes an inorganic zirconium source, which includes one or more of zirconium oxychloride octahydrate, zirconium chloride, zirconium hydroxide, and zirconium-oxygen clusters.

4. The MOF-808 material based on zirconium acetylacetonate as described in claim 3, characterized in that: The molar ratio of zirconium acetylacetonate to inorganic zirconium source is 2:8~0.5:9.

5.

5. A method for preparing the MOF-808 material according to claim 1 or 3, characterized in that: The solution was prepared by mixing zirconium source, pyromellitic acid, formic acid and N,N-dimethylformamide, and then synthesized in one step by microwave irradiation reaction.

6. The method for preparing MOF-808 material as described in claim 5, characterized in that: The microwave reaction temperature is 30~150℃, and the reaction time is 10~90min.

7. The method for preparing MOF-808 material as described in claim 5, characterized in that: The mixed solution also includes a titanium source.

8. The method for preparing MOF-808 material as described in claim 5, characterized in that: The volume ratio of formic acid to N,N-dimethylformamide is 90:10 to 30:70; the molar volume ratio of zirconium source to DMF is 1 mmol : 2 to 14 mL.

9. The application of the MOF-808 material according to any one of claims 1-4 in the catalytic degradation of DEPPT.

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