A method for preparing high-stability MOFs thermodynamic metastable state ordered defects
By treating with high-equivalent metal salts and ligand solutions, combined with ultrasonic, hydrothermal, and vacuum activation steps, ordered defect MOFs were prepared, solving the problem of disordered defect distribution and achieving the synthesis of MOFs with higher stability and better performance, especially in catalysis and adsorption.
Patent Information
- Application Number
- CN202411832996.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2044-12-13
AI Technical Summary
Existing technologies make it difficult to achieve a controllable distribution of defects in MOFs, leading to disordered MOF structures and hindering the study of structure-property relationships. In particular, the synthesis of highly stable thermodynamic metastable MOFs remains a challenge.
By preparing high-equivalent metal salt and ligand solutions, combined with ultrasonic treatment, hydrothermal reaction, solvent exchange and vacuum activation, MOF structures with ordered defects were prepared. The synthesis of ordered defects was achieved by utilizing self-template-induced nucleation and lattice-matched growth mechanisms.
The synthesized ordered defect MOFs have a larger specific surface area and pore size, providing more open metal sites and significantly improving catalytic and adsorption performance, such as showing higher conversion rates in the hydrolysis reaction of nerve agent mimics.
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Figure CN119431820B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of defect or metastable MOFs synthesis, and relates to a preparation method of high-stability MOFs thermodynamic metastable ordered defects, in particular to ordered defect MOFs obtained by a method of high-equivalent metal salt and high-equivalent modulator. BACKGROUND
[0002] Metal-organic frameworks (MOFs) are an attractive field of research with important applications in gas storage, sensing, catalysis, etc. Defects are inherent properties of solid crystalline materials and play a key role in determining and influencing material performance. As a crystalline porous material, MOFs are no exception to being affected by defects. Defect engineering has become a favorable tool to adjust and optimize the performance of MOFs (see Daliran, S., et al. Defect-enabling zirconium-based metal–organic frameworks for energy and environmental remediation applications. Chem. Soc. Rev. 53, 6244-6294 (2024)). Although there are many related studies on controlling the number and type of defects, achieving precise control of defect distribution remains a major challenge (see Han, Y., et al. Trace benzene capture by decoration of structural defects in metal–organic framework materials. Nat. Mater. 23, 1531-1538 (2024)). The distribution of defects is currently random, which destroys the order of MOFs and hinders the study of structure-property relationships. The current synthesis method, especially the de novo synthesis method, is difficult to achieve controllable distribution of defects, and it is still a major challenge to achieve ordered defects that meet the thermodynamic metastable phase, especially high-stability MOFs.
[0003] The application proposes a preparation method of high-stability ordered defect MOFs, and obtains a new structure with ordered defects. This method can be extended to various metals and ligands. Ordered defect MOFs have better application performance than defect-free and disordered defect MOFs, for example, in catalysis, adsorption, etc. SUMMARY
[0004] The purpose of the application is to propose a preparation method of high-stability ordered defect MOFs in view of the shortcomings and deficiencies of the current synthesis technology.
[0005] The technical scheme of the application is as follows:
[0006] A preparation method of high-stability MOFs thermodynamic metastable ordered defects, steps as follows:
[0007] (1) configure high equivalent metal salt solution I, after adding high equivalent metal salt solution I to high equivalent monocarboxylic acid under stirring, ultrasonic treatment is carried out;
[0008] (2) configure ligand solution II, add ligand solution II to the mixed solution of high equivalent monocarboxylic acid and metal salt, after stirring, seal and carry out hydrothermal reaction; after hydrothermal reaction, naturally cool to room temperature, filter the obtained solid and wash with solvent;
[0009] (3) solvent exchange is carried out on the solid obtained in step (2), and then the solvent exchanged solid is activated under vacuum, and the MOFs structure with the composition of M x O y L z is obtained after activation treatment, wherein M=alkaline earth metal, third main group metal, transition metal such as Zr, Hf, Y, Eu; L=polycarboxylic acid of different lengths such as fumaric acid, terephthalic acid, diphenic acid, and polycarboxylic acid modified by different types and different numbers of functional groups; the MOFs structure of M x O y L z is an ordered defect structure with multiple open metal sites per cluster, and the molar ratio of ligand:cluster of the MOFs structure is L:M x =z:1 (z=1-8).
[0010] The molar ratio of metal salt, monocarboxylic acid and ligand is (5-30):(125-500):1.
[0011] The metal salt is one of alkaline earth metal salt, third main group metal salt, Zr, Hf, Y, Eu and other transition metal salt.
[0012] The ligand is polycarboxylic acid of different lengths such as fumaric acid, terephthalic acid, diphenic acid, and polycarboxylic acid modified by different types and different numbers of functional groups.
[0013] The monocarboxylic acid is formic acid or acetic acid.
[0014] The solvent used for configuring metal salt solution I and ligand solution II is N,N dimethylformamide or N,N dimethylacetamide.
[0015] The ultrasonic treatment temperature is 20-50℃, and the time is 20-50 minutes.
[0016] The hydrothermal reaction temperature is 100-150℃, and the time is 36-72h.
[0017] The solvent exchange is carried out by using the same solvent as used in steps (1) and (2) and methanol in sequence, and the stirring time is 12-24 hours.
[0018] The temperature of the activation treatment under vacuum is 90-150℃, and the time is 10-24h.
[0019] The beneficial effects of the present application are:
[0020] 1. The present application realizes the synthesis of a new structure with ordered defects by synthesizing thermodynamically metastable ordered defect MOFs under the guidance of self-template induced nucleation and lattice matching growth mechanism in the condition of high concentration monocarboxylic acid and metal salt.
[0021] 2. By changing the proportion of metal salt and ligand, MOFs with ordered defects can be obtained.
[0022] 3. The new structure with ordered defects synthesized in the present application has more open sites and larger pore size compared with the disordered defect structure, and the performance is significantly improved in catalysis, adsorption, etc., such as Lewis acid catalytic reactions of nerve agent analog hydrolysis, oxidation of styrene ring opening, and carbon dioxide ring addition. More open sites and larger pore size caused by ordered defects are more conducive to substrate diffusion, thus promoting the catalysis of the reaction. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The XRD image of the ordered defect MOFs synthesized in Example 1.
[0024] Figure 2 The XRD image of the ordered defect MOFs synthesized in Example 2.
[0025] Figure 3 The thermogravimetric curve of the ordered defect MOFs synthesized in Example 1.
[0026] Figure 4 The nitrogen adsorption isotherm image of the ordered defect MOFs synthesized in Example 1.
[0027] Figure 5 The scanning electron microscope image of the ordered defect MOFs synthesized in Example 1.
[0028] Figure 6 The XRD image of the disordered defect MOFs synthesized in Comparative Example 1.
[0029] Figure 7 The XRD image of the disordered defect MOFs synthesized in Comparative Example 2.
[0030] Figure 8 XRD pattern of the disordered defect MOF synthesized in Comparative Example 3. DETAILED DESCRIPTION
[0031] The specific embodiments of the present application are further illustrated in the following with reference to the accompanying drawings and technical solutions.
[0032] Example 1
[0033] The preparation method of the high-stability ordered defect MOF comprises the following steps:
[0034] (1) 60 mL of N,N-dimethylformamide and 9.6 mmol of zirconium chloride were added into a beaker, and ultrasonic stirring was used to accelerate dissolution to obtain solution I;
[0035] (2) 3 mL of formic acid was added into a 30 mL glass bottle, and solution I was transferred into the 30 mL glass bottle under stirring, and after sufficient stirring, the 30 mL glass bottle was transferred into an ultrasonic oscillator for ultrasonic treatment;
[0036] (3) 16 mL of N,N-dimethylformamide and 1.28 mmol of terephthalic acid were added into a beaker, and stirring was used to dissolve to obtain solution II;
[0037] (4) The 30 mL glass bottle after ultrasonic treatment was taken out, and solution II was added into the glass bottle under stirring, and after sealing, it was placed in an oven for hydrothermal reaction, and heated at 120°C for 72 h;
[0038] (5) The glass bottle after reaction in step (4) was taken out and naturally cooled to room temperature, and the obtained solid was filtered out and washed with N,N-dimethylformamide for multiple times;
[0039] (6) The solid obtained in step (5) was filtered out and solvent exchange was performed using N,N-dimethylformamide and methanol, and the sample after solvent exchange was subjected to activation treatment under vacuum, and the activation temperature was 90°C and the time was 20 h.
[0040] Example 2
[0041] The preparation method of the high-stability ordered defect MOF comprises the following steps:
[0042] (1) 60 mL of N,N-dimethylformamide and 19.2 mmol of zirconium chloride were added into a beaker, and ultrasonic stirring was used to accelerate dissolution to obtain solution I;
[0043] (2) 6 mL of formic acid was added into a 30 mL glass bottle, and solution I was transferred into the 30 mL glass bottle under stirring, and after sufficient stirring, the 30 mL glass bottle was transferred into an ultrasonic oscillator for ultrasonic treatment;
[0044] (3) In a beaker, 16 mL of N,N-dimethylformamide and 1.28 mmol of terephthalic acid were added, and stirring was performed to obtain a solution II;
[0045] (4) The 30 mL glass bottle after ultrasonic treatment was taken out, and solution II was added to the glass bottle while stirring was maintained. After sealing, the glass bottle was placed in an oven for hydrothermal reaction, and heating was performed at 150°C for 24 h;
[0046] (5) The glass bottle after reaction in step (4) was taken out and naturally cooled to room temperature. The obtained solid was filtered out and washed with N,N-dimethylformamide for multiple times;
[0047] (6) The solid obtained in step (5) was filtered out and subjected to solvent exchange with N,N-dimethylformamide and methanol. The sample after solvent exchange was subjected to activation treatment under vacuum, and the activation temperature was 150°C, and the time was 10 h.
[0048] In Example 3, the zirconium chloride in step (1) in Example 1 was replaced with hafnium chloride, and the other conditions were the same as in Example 1.
[0049] In Example 4, the zirconium chloride in step (1) in Example 1 was replaced with europium nitrate, and the other conditions were the same as in Example 1.
[0050] In Example 5, the terephthalic acid in step (3) in Example 1 was replaced with methyl terephthalic acid, and the other conditions were the same as in Example 1.
[0051] In Example 6, the terephthalic acid in step (3) in Example 1 was replaced with hydroxy terephthalic acid, and the other conditions were the same as in Example 1.
[0052] In Example 7, the terephthalic acid in step (3) in Example 1 was replaced with amino terephthalic acid, and the other conditions were the same as in Example 1.
[0053] In Example 8, the terephthalic acid in step (3) in Example 1 was replaced with methoxy terephthalic acid, and the other conditions were the same as in Example 1.
[0054] Comparative Example 1
[0055] The preparation method of the disordered defect MOFs comprises the following steps:
[0056] (1) 60 mL of N,N-dimethylformamide and 9.6 mmol of zirconium chloride were added to a beaker, and ultrasonic stirring was performed to accelerate dissolution to obtain a solution I;
[0057] (2) 1 mL of formic acid was added to a 30 mL glass bottle, and the solution I was transferred to the 30 mL glass bottle while stirring was maintained. After stirring was performed, the 30 mL glass bottle was transferred to an ultrasonic oscillator for ultrasonic treatment;
[0058] (3) In a beaker, 16 mL of N,N-dimethylformamide and 1.28 mmol of terephthalic acid were added, and stirring was performed to obtain solution II;
[0059] (4) The 30 mL glass bottle after ultrasonic treatment was taken out, and solution II was added to the glass bottle while stirring was maintained. After sealing, the glass bottle was placed in an oven for hydrothermal reaction, and heating was performed at 150°C for 24 h;
[0060] (5) The glass bottle after reaction in step (4) was taken out and naturally cooled to room temperature. The obtained solid was filtered out and washed with N,N-dimethylformamide for multiple times;
[0061] (6) The solid obtained in step (5) was filtered out and solvent exchange was performed using N,N-dimethylformamide and methanol. The sample after solvent exchange was subjected to activation treatment under vacuum, and the activation temperature was 150°C and the time was 10 h.
[0062] Comparative Example 2
[0063] The preparation method of the disordered defect MOFs comprises the following steps:
[0064] (1) In a beaker, 60 mL of N,N-dimethylformamide and 2.4 mmol of zirconium chloride were added, and ultrasonic stirring was performed to accelerate dissolution to obtain solution I;
[0065] (2) In a 30 mL glass bottle, 3 mL of formic acid was added, and solution I was transferred to the 30 mL glass bottle while stirring was maintained. After sufficient stirring, the 30 mL glass bottle was transferred to an ultrasonic oscillator for ultrasonic treatment;
[0066] (3) In a beaker, 16 mL of N,N-dimethylformamide and 1.28 mmol of terephthalic acid were added, and stirring was performed to obtain solution II;
[0067] (4) The 30 mL glass bottle after ultrasonic treatment was taken out, and solution II was added to the glass bottle while stirring was maintained. After sealing, the glass bottle was placed in an oven for hydrothermal reaction, and heating was performed at 150°C for 24 h;
[0068] (5) The glass bottle after reaction in step (4) was taken out and naturally cooled to room temperature. The obtained solid was filtered out and washed with N,N-dimethylformamide for multiple times;
[0069] (6) The solid obtained in step (5) was filtered out and solvent exchange was performed using N,N-dimethylformamide and methanol. The sample after solvent exchange was subjected to activation treatment under vacuum, and the activation temperature was 150°C and the time was 10 h.
[0070] Comparative Example 3
[0071] The preparation method of the disordered defect MOF comprises the following steps:
[0072] (1) 60 mL of N,N-dimethylformamide and 2.4 mmol of zirconium chloride were added into a beaker, and ultrasonic stirring was used to accelerate dissolution to obtain solution I;
[0073] (2) 1 mL of formic acid was added into a 30 mL glass bottle, and solution I was transferred into the 30 mL glass bottle under stirring, and after sufficient stirring, the 30 mL glass bottle was transferred into an ultrasonic oscillator for ultrasonic treatment;
[0074] (3) 16 mL of N,N-dimethylformamide and 1.28 mmol of terephthalic acid were added into a beaker, and stirring was used to dissolve to obtain solution II;
[0075] (4) The 30 mL glass bottle after ultrasonic treatment was taken out, and solution II was added into the glass bottle under stirring, and after sealing, the glass bottle was placed into an oven for hydrothermal reaction, and heating was performed at 150 DEG C for 24 h;
[0076] (5) The glass bottle after reaction in step (4) was taken out and naturally cooled to room temperature, and the obtained solid was filtered out and washed with N,N-dimethylformamide for multiple times;
[0077] (6) The solid obtained in step (5) was filtered out and subjected to solvent exchange with N,N-dimethylformamide and methanol, and the sample after solvent exchange was subjected to activation treatment under vacuum, and the activation temperature was 150 DEG C, and the time was 10 h.
[0078] Application example
[0079] The high-stability ordered defect MOF has a significant performance improvement in applications such as catalysis and adsorption, and the Lewis acid catalytic reaction is taken as an example of the hydrolysis reaction of a nerve agent mimic (DMNP).
[0080] The steps are as follows: 10% D2O / H2O buffer solution of N-ethylmorpholine and the catalysts of example 1, comparative example 1, comparative example 2, comparative example 3 were added into a reactor, and the catalysts were example 1, comparative example 1, comparative example 2, comparative example 3, and the catalyst ratio was 3 mol% of DMNP, and stirring was performed at room temperature until complete dispersion. DMNP was added to start the reaction, and samples were taken at 5, 10, 15, 20 and 30 minutes after the start of the reaction, and nuclear magnetic resonance spectroscopy was used for characterization.
[0081] The results are as follows: example 1 can be converted by 50% in 5 minutes, comparative example 1 can be converted by 22.5% under the same conditions, comparative example 2 can be converted by 23.9% under the same conditions, and comparative example 3 can be converted by 15.7% under the same conditions.
[0082] The results show that, due to the existence of ordered defects, more metal open sites and larger pore size are produced in Example 1, which is beneficial to the diffusion and hydrolysis of the substrate DMNP, and thus the conversion rate is higher in the same time.
Claims
1. A method for preparing ordered defects in a thermodynamically metastable state of a highly stable MOF, characterized in that, The steps are as follows: (1) Prepare metal salt solution I. After adding metal salt solution I to a monocarboxylic acid while stirring, perform ultrasonic treatment. (2) Prepare ligand solution II. Add ligand solution II to a mixed solution of monocarboxylic acid and metal salt, stir and seal, and carry out hydrothermal reaction. After hydrothermal reaction, cool naturally to room temperature, filter the obtained solid and wash it with solvent. The molar ratio of the metal salt, monocarboxylic acid, and ligand is (5-30):(125-500):1; (3) The solid obtained in step (2) is subjected to solvent exchange, and then the solid after solvent exchange is activated under vacuum. After activation, the solid with the structure M is obtained. x O y L z The MOF structure, where M = transition metal; L = functionalized polycarboxylic acid; M x O y L z The MOF structure has a ligand:cluster molar ratio of L:M. x =z:1, z=1-8, each cluster has an ordered defect structure with multiple open metal sites.
2. The preparation method according to claim 1, characterized in that, The metal salt mentioned is a transition metal salt.
3. The preparation method according to claim 1, characterized in that, The ligand is one of fumaric acid, terephthalic acid, and biphenyl acid.
4. The preparation method according to claim 1, characterized in that, The monocarboxylic acid mentioned is formic acid or acetic acid.
5. The preparation method according to claim 1, characterized in that, The solvents used to prepare metal salt solution I and ligand solution II are both N,N-dimethylformamide or N,N-dimethylacetamide.
6. The preparation method according to claim 1, characterized in that, The ultrasonic treatment is performed at a temperature of 20℃-50℃ for 20-50 minutes.
7. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 100℃-150℃ for a time of 36-72 h.
8. The preparation method according to claim 5, characterized in that, The solvent exchange is performed by sequentially exchanging the solid with a solvent and methanol, respectively. The solvent is the same as the solvent used in steps (1) and (2), and the stirring time is 12-24 hours.
9. The preparation method according to claim 1, characterized in that, The vacuum activation treatment is performed at a temperature of 90-150℃ for 10-24 hours.