Preparation method of hydrophobic metal organic framework
Through the method of reacting metal soap salts with organic ligands in organic solvents, the problems of water instability and poor lipophilicity of metal organic frame materials are solved, and efficient and uniform superhydrophobic metal organic frame synthesis is achieved, which is suitable for a variety of application fields.
Patent Information
- Application Number
- CN202411591273.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-03-11
AI Technical Summary
The existing metal organic frame materials have problems such as water instability, poor lipophilicity, and low synthetic concentration, which limit their application.
The superhydrophobic metal organic framework is synthesized by a one-step method using metal soap salt and organic ligand to react in an organic solvent, and stearate is used as a metal source to bring in hydrophobic groups to improve the water stability and hydrophobicity of the material.
It has achieved high concentration, large batch and high efficiency synthesis, uniform material size and excellent hydrophobicity, and is suitable for gas storage, separation or catalysis.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of metal organic framework materials, and in particular to a method for preparing a hydrophobic metal organic framework. Background Art
[0002] Metal-organic frameworks (MOFs) are a class of crystalline materials with high specific surface area, which are composed of second building blocks (SBUs) composed of inorganic metals and multifunctional organic linkers connected by self-assembly. The wide range of metal ions in the second building blocks and the designability of organic linkers make them widely used in medicine, organic synthesis, catalysis, energy, polymers and gas adsorption and separation, and have great development potential.
[0003] At present, the synthesis methods of metal organic frameworks have been expanded to about ten kinds, mainly including: hydrothermal / solvothermal method, ultrasonic method, microwave heating method, electrochemical synthesis (anodic synthesis method, cathode synthesis method, indirect bipolar electrodeposition method, electroplating displacement method and electrophoretic deposition method), mechanochemistry, solution diffusion method, sol-gel method, ion thermal method, etc. However, these preparation methods have certain common problems, such as the water instability, poor lipophilicity and low synthesis concentration of the prepared metal organic frameworks, which limit the use of metal organic frameworks.
[0004] There are two main strategies to improve the hydrophobicity of metal organic frameworks. One is the ligand modification method, which uses organic ligands with hydrophobic groups to coordinate with metal ions and directly introduce hydrophobic groups into the metal organic framework; the other is the post-modification method, which first prepares the metal organic framework and then coats it with hydrophobic polymers. However, the ligand modification method may affect the coordination of organic ligands with metal ions, the structure and yield of the metal organic framework, etc., while the post-modification method has cumbersome steps and may affect the surface pore structure of the material. Summary of the invention
[0005] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the purposes of the present invention is to provide a method for preparing a hydrophobic metal organic framework; the second purpose of the present invention is to provide a hydrophobic metal organic framework prepared by the method; the third purpose of the present invention is to provide the application of the hydrophobic metal organic framework.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is:
[0007] A first aspect of the present invention provides a method for preparing a hydrophobic metal organic framework, comprising the following steps:
[0008] S1, dissolving the metal soap salt and the organic ligand in an organic solvent respectively to obtain a metal soap salt solution and an organic ligand solution;
[0009] S2, adding the organic ligand solution dropwise to the metal soap salt solution to react and obtain the hydrophobic metal organic framework.
[0010] Preferably, in step S1, the metal soap salt includes stearate; further preferably, the metal soap salt is selected from at least one of zinc stearate, magnesium stearate, iron stearate, copper stearate, cobalt stearate, calcium stearate, zirconium stearate, aluminum stearate, and chromium stearate.
[0011] Preferably, in step S1, the organic ligand is selected from at least one of benzimidazole, imidazole, 2-methylimidazole, terephthalic acid, 2-aminoterephthalic acid, 2,5-hydroxyterephthalic acid, isophthalic acid, phthalic acid, trimesic acid, trimellitic acid and their derivatives.
[0012] Preferably, in step S1, the organic solvent is selected from at least one of methanol, ethanol, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.
[0013] Preferably, in step S1, the metal soap salt and the organic ligand are dissolved in the same organic solvent.
[0014] Preferably, in step S1, the concentration ratio of the metal soap salt solution to the organic ligand solution is (0.125-2):1; further preferably, the concentration ratio of the metal soap salt solution to the organic ligand solution is (0.25-1):1.
[0015] Preferably, in step S1, the concentration of the metal soap salt solution is 0.01-1 mol / L; further preferably, the concentration of the metal soap salt solution is 0.02-0.5 mol / L.
[0016] Preferably, in step S1, the concentration of the organic ligand solution is 0.01-1 mol / L; further preferably, the concentration of the organic ligand solution is 0.05-0.5 mol / L.
[0017] Preferably, in step S1, the dissolution of the metal soap salt and the organic ligand is performed by heating; the heating temperature is selected from 70-150°C.
[0018] Preferably, in step S1, the dissolution of the metal soap salt and the organic ligand is assisted by stirring.
[0019] Preferably, in step S1, the stirring speed is 300-800 r / min; further preferably, the stirring speed is 400-600 r / min.
[0020] Preferably, in step S2, the volume ratio of the organic ligand solution to the metal soap salt solution is 1:(0.8-1.2); further preferably, the volume ratio of the organic ligand solution to the metal soap salt solution is 1:(0.9-1.1).
[0021] Preferably, in step S2, the reaction temperature is 70-150°C, and the reaction time is 0.1-24h; further preferably, the reaction temperature is 70-140°C, and the reaction time is 0.1-2h.
[0022] Preferably, in step S2, the reaction process is assisted by stirring.
[0023] Preferably, in step S2, the stirring speed is 500-1000 r / min; further preferably, the stirring speed is 500-800 r / min.
[0024] Preferably, in the step S2, after the reaction is completed, the steps of collecting the product by suction filtration and washing with a solvent are also included.
[0025] Preferably, the solvent washing is to wash the product after heating the solvent to near boiling point.
[0026] Preferably, the solvent is selected from at least one of methanol, ethanol, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide; more preferably, the solvent is N,N-dimethylformamide at 150°C.
[0027] The second aspect of the present invention provides a hydrophobic metal organic framework prepared by the preparation method described in the first aspect of the present invention.
[0028] The third aspect of the present invention provides the use of the hydrophobic metal organic framework described in the second aspect of the present invention in the field of gas storage and separation, or catalysis.
[0029] Compared with the prior art, the present invention has the following beneficial effects:
[0030] 1) The preparation method of the hydrophobic metal organic framework provided by the present invention adopts metal soap salt as the metal ion source, which overcomes the problems of easy deliquesce and low safety caused by nitrate and chloride salt in the traditional process, solves the problems of metal source stability and high cost, and lays an excellent foundation for large-scale industrial production;
[0031] 2) The method for preparing the hydrophobic metal organic framework provided by the present invention has simple steps, mild conditions and high efficiency. The metal soap anion can be used as a molecular regulator to synthesize a super hydrophobic metal organic framework with a capped soap group and a large number of hydrophobic alkyl chains, which can effectively improve the stability of the metal organic framework in water;
[0032] 3) The preparation method of the hydrophobic metal organic framework provided by the present invention is universal and applicable to the preparation of various types of existing metal organic frameworks. It overcomes the problems of long synthesis time, low concentration and complex operation of the reactor in the traditional method, and realizes high-concentration, large-scale and high-efficiency synthesis;
[0033] 4) The metal organic framework prepared by the preparation method provided by the present invention has uniform size and excellent hydrophobicity, and can meet the application requirements of gas storage and separation, or catalysis. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 is the XRD pattern of the metal organic framework ZIF-8-Ⅰ in Example 1;
[0035] Figure 2 is the XRD pattern of the metal organic framework Zn-MOF-74 in Example 3;
[0036] Figure 3 is the XRD pattern of the metal organic framework HKUST-1-Ⅰ in Example 5;
[0037] Figure 4 is the XRD pattern of the metal organic framework ZIF-67-Ⅰ in Example 11;
[0038] Figure 5 IR spectra of the metal organic frameworks in Example 1(a) and Comparative Example 1(b);
[0039] Figure 6 IR spectra of the metal organic frameworks in Example 5 (a) and Comparative Example 3 (b);
[0040] Figure 7 IR spectra of the metal organic frameworks in Example 11(a) and Comparative Example 2(b);
[0041] Figure 8 is a SEM image of the metal organic framework in Example 11;
[0042] Fig. 9 SEM images of the metal organic frameworks in Example 5 (a) and Comparative Example 3 (b);
[0043] Fig.10 Graphs showing water contact angles of the metal organic frameworks in Example 1 (a) and Comparative Example 1 (b);
[0044] Fig.11 This is a water contact angle diagram of the metal organic framework Zn-MOF-74 in Example 3;
[0045] Fig.12This is a water contact angle diagram of the metal organic framework Zn-HKUST-1 in Example 4;
[0046] Fig.13 This is a water contact angle diagram of the metal organic framework HKUST-1-Ⅰ in Example 5;
[0047] Fig.14 This is a water contact angle diagram of the metal organic framework Mg-MOF-74 in Example 6;
[0048] Fig.15 is a water contact angle diagram of the metal organic framework Fe-MIL-101 in Example 9;
[0049] Fig.16 This is the water contact angle diagram of the metal organic framework ZIF-67-Ⅰ in Example 11.
[0050] Fig.17 This is a comparison chart of the catalytic performance of the metal organic framework in Example 5 and Comparative Example 3. DETAILED DESCRIPTION
[0051] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.
[0052] Example 1
[0053] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0054] S11, add 2 mmol zinc stearate to 50 mL ethanol, heat to 75°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0055] S12, adding 4 mmol 2-methylimidazole to 50 mL ethanol, heating to 75° C., stirring at 500 r / min to obtain solution B;
[0056] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 75°C, stir at 700 r / min, react for 0.5 h, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-8-Ⅰ.
[0057] Example 2
[0058] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0059] S11, add 1 mmol zinc stearate to 25 mL ethanol, heat to 130°C, and stir at 700 r / min until completely dissolved to prepare solution A;
[0060] S12, adding 4 mmol of 2-methylimidazole to 25 mL of ethanol, heating to 130° C., and stirring at 500 r / min to obtain solution B;
[0061] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 500 r / min, react for 0.1 h, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework ZIF-8-Ⅱ.
[0062] Example 3
[0063] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0064] S11, add 5 mmol zinc stearate to 25 mL N,N-dimethylformamide, heat to 130°C, and stir at 600 r / min until completely dissolved to prepare solution A;
[0065] S12, adding 5 mmol of 2,5-hydroxyterephthalic acid to 25 mL of N,N-dimethylformamide, heating to 130° C., stirring at 500 r / min to obtain solution B;
[0066] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 800 r / min, react for 0.5 h, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework Zn-MOF-74.
[0067] Example 4
[0068] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0069] S11, add 3 mmol zinc stearate to 25 mL N,N-dimethylformamide, heat to 130°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0070] S12, adding 2 mmol of trimesic acid to 25 mL of N,N-dimethylformamide, heating to 120°C, stirring at 400 r / min to obtain solution B;
[0071] S21. Solution B was slowly added dropwise to solution A, the temperature was maintained at 130°C, stirring was performed at 800 r / min, the reaction was performed for 2 h, the powder was collected by filtration, and washed three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which was recorded as metal organic framework Zn-HKUST-1.
[0072] Example 5
[0073] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0074] S11, add 2 mmol copper stearate to 25 mL N,N-dimethylformamide, heat to 140°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0075] S12, adding 3.6 mmol of trimesic acid into 25 mL of N,N-dimethylformamide, heating to 130°C, stirring at 400 r / min to obtain solution B;
[0076] S21. Solution B was slowly added dropwise to solution A, the temperature was maintained at 140°C, stirring was performed at 800 r / min, the reaction was performed for 2 h, the powder was collected by filtration, and washed three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which was recorded as the metal organic framework HKUST-1-Ⅰ.
[0077] Example 6
[0078] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0079] S11, add 2.5mmol magnesium stearate to 25mL N,N-dimethylformamide, heat to 140°C, and stir at 600r / min until completely dissolved to prepare solution A;
[0080] S12, adding 5 mmol of 2,5-hydroxyterephthalic acid to 25 mL of N,N-dimethylformamide, heating to 130° C., stirring at 500 r / min to obtain solution B;
[0081] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 800 r / min, react for 1 hour, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework Mg-MOF-74.
[0082] Example 7
[0083] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0084] S11, add 2 mmol of iron stearate to 25 mL of N,N-dimethylformamide, heat to 140°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0085] S12, adding 3.6 mmol of trimesic acid into 25 mL of N,N-dimethylformamide, heating to 130°C, stirring at 400 r / min to obtain solution B;
[0086] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 140°C, stir at 800 r / min, react for 1 hour, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework Fe-BTC.
[0087] Example 8
[0088] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0089] S11, add 2 mmol aluminum stearate to 25 mL N,N-dimethylformamide, heat to 140°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0090] S12, add 4 mmol of trimesic acid into 25 mL of N,N-dimethylformamide, heat to 130°C, and stir at 400 r / min to obtain solution B;
[0091] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 140°C, stir at 800 r / min, react for 1 hour, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework Al-BTC.
[0092] Example 9
[0093] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0094] S11, add 4 mmol of iron stearate to 25 mL of N,N-dimethylformamide, heat to 140°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0095] S12, adding 2 mmol of trimesic acid to 25 mL of N,N-dimethylformamide, heating to 120°C, stirring at 400 r / min to obtain solution B;
[0096] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 140°C, stir at 800 r / min, react for 1 hour, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework Fe-MIL-101.
[0097] Example 10
[0098] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0099] S11, add 5 mmol of cobalt stearate to 25 mL of N,N-dimethylformamide, heat to 130°C, and stir at 400 r / min until completely dissolved to prepare solution A;
[0100] S12, adding 2.5 mmol 2,5-hydroxyterephthalic acid into 25 mL N,N-dimethylformamide, heating to 130° C., stirring at 400 r / min to obtain solution B;
[0101] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 500 r / min, react for 1 hour, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework Co-MOF-74.
[0102] Embodiment 11
[0103] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0104] S11, add 2.5mmol of cobalt stearate to 25mL of N,N-dimethylformamide, heat to 130°C, and stir at 400r / min until completely dissolved to prepare solution A;
[0105] S12, adding 5 mmol 2-methylimidazole to 25 mL N,N-dimethylformamide, heating to 80°C, stirring at 400 r / min to obtain solution B;
[0106] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 500 r / min, react for 1 hour, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-67-Ⅰ.
[0107] Example 12
[0108] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0109] S11, add 2 mmol of cobalt stearate to 50 mL of ethanol, heat to 75°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0110] S12, adding 5 mmol of 2-methylimidazole to 50 mL of ethanol, heating to 75° C., and stirring at 500 r / min to obtain solution B;
[0111] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 75°C, stir at 600 r / min, react for 0.5 h, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-67-Ⅱ.
[0112] Example 13
[0113] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0114] S11, add 5 mmol nickel stearate to 25 mL N,N-dimethylformamide, heat to 130°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0115] S12, adding 2.5 mmol 2,5-hydroxyterephthalic acid into 25 mL N,N-dimethylformamide, heating to 130° C., stirring at 500 r / min to obtain solution B;
[0116] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 700 r / min, react for 1 hour, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework Ni-MOF-74.
[0117] Embodiment 14
[0118] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0119] S11, add 5 mmol of zirconium stearate to 25 mL of N,N-dimethylformamide, heat to 130°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0120] S12, adding 5 mmol of 2-aminoterephthalic acid to 25 mL of N,N-dimethylformamide, heating to 130° C., stirring at 500 r / min to obtain solution B;
[0121] S21, solution B was slowly added dropwise to solution A, the temperature was maintained at 130°C, stirring was performed at 500 r / min, the reaction was continued for 2 h, the powder was collected by filtration, and washed three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which was recorded as the metal organic framework UiO-66-NH 2 .
[0122] Embodiment 15
[0123] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0124] S11, add 4 mmol of chromium stearate to 25 mL of N,N-dimethylformamide, heat to 140°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0125] S12, adding 2 mmol of terephthalic acid into 25 mL of N,N-dimethylformamide, heating to 120°C, stirring at 500 r / min to obtain solution B;
[0126] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 140°C, stir at 800 r / min, react for 1 hour, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, recorded as metal organic framework Cr-MIL-101.
[0127] Example 16
[0128] This embodiment provides a metal organic framework, and the preparation steps are as follows:
[0129] S11, add 1 mmol zinc stearate to a mixed solution of 12.5 mL N,N-dimethylformamide and 25 mL ethanol, heat to 130°C, and stir at 500 r / min until completely dissolved to prepare solution A;
[0130] S12, adding 4 mmol of terephthalic acid to a mixed solution of 12.5 mL of N,N-dimethylformamide and 25 mL of ethanol, heating to 70° C., and stirring at 500 r / min to obtain a solution B;
[0131] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 500 r / min, react for 0.1 h, collect the powder by filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-8-Ⅲ.
[0132] Comparative Example 1
[0133] This comparative example provides a metal organic framework, and the preparation steps are as follows:
[0134] S11, add 2mmol zinc nitrate to 25mL N,N-dimethylformamide, heat to 70°C, and stir at 500r / min until completely dissolved to prepare solution A;
[0135] S12, adding 4 mmol 2-methylimidazole to 25 mL N,N-dimethylformamide, heating to 70°C, stirring at 500 r / min to obtain solution B;
[0136] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 130°C, stir at 500 r / min, react for 0.1 h, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-8-Ⅳ.
[0137] Comparative Example 2
[0138] This comparative example provides a metal organic framework, and the preparation steps are as follows:
[0139] S11, add 2.5mmol of cobalt nitrate to 50mL of ethanol, heat to 75°C, and stir at 500r / min until completely dissolved to prepare solution A;
[0140] S12, adding 5 mmol of 2-methylimidazole to 50 mL of ethanol, heating to 75° C., and stirring at 500 r / min to obtain solution B;
[0141] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 75°C, stir at 600 r / min, react for 0.5 h, collect the powder by filtration, and wash three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as metal organic framework ZIF-67-Ⅲ.
[0142] Comparative Example 3
[0143] This comparative example provides a metal organic framework, and the preparation steps are as follows:
[0144] S11, add 2mmol copper nitrate to 25mL N,N-dimethylformamide, heat to 140℃, stir at 500r / min until completely dissolved, to prepare solution A;
[0145] S12, adding 3.6 mmol of trimesic acid into 25 mL of N,N-dimethylformamide, heating to 130°C, stirring at 400 r / min to obtain solution B;
[0146] S21. Slowly add solution B dropwise into solution A, maintain the temperature at 140°C, stir at 800 r / min, react for 2 h, collect the powder by suction filtration, and wash it three times with 150°C N,N-dimethylformamide to obtain a powdery solid, which is recorded as the metal organic framework HKUST-1-Ⅱ.
[0147] Material Characterization and Performance Testing
[0148] 1. X-ray diffraction test was performed on the metal organic framework materials prepared in Examples 1, 3, 5 and 11:
[0149] Figure 1 is the XRD pattern of the metal organic framework ZIF-8-Ⅰ in Example 1, Figure 2 is the XRD pattern of the metal organic framework Zn-MOF-74 in Example 3, Figure 3 is the XRD pattern of the metal organic framework HKUST-1-Ⅰ in Example 5, Figure 4 is the XRD pattern of the metal organic framework ZIF-67-Ⅰ in Example 11. Figure 1-Figure 4 It can be seen that the metal organic framework prepared in the example has a good crystalline structure, and its characteristic diffraction peak is consistent with that of a conventional metal organic framework, indicating that a well-crystallized metal organic framework crystal can be obtained using stearate as a precursor.
[0150] 2. Infrared spectrum test was performed on the metal organic framework materials prepared in Examples 1, 5, 11 and Comparative Examples 1-3:
[0151] Figure 5 : are infrared spectra of the metal organic frameworks in Example 1(a) and Comparative Example 1(b), Figure 6 The infrared spectra of the metal organic frameworks in Example 5 (a) and Comparative Example 3 (b) are shown in FIG. Figure 7 The infrared spectra of the metal organic framework in Example 11 (a) and Comparative Example 2 (b) are shown in FIG. Figure 5-Figure 7 It can be seen that compared with the conventional metal organic framework prepared in the comparative example, the metal organic frameworks ZIF-8-Ⅰ, HKUST-1-Ⅰ and ZIF-67-Ⅰ in the examples have a peak at 2852 cm -1 and 2920cm -1 Obvious fatty characteristic diffraction peaks appear at the , indicating that using stearate as a metal precursor, the stearate group can coordinate with the metal ions in the metal-organic framework, and its hydrophobic fatty long hydrocarbon chain makes the metal-organic framework superhydrophobic.
[0152] 3. Scanning electron microscopy test was performed on the metal organic framework materials prepared in Examples 5, 11 and Comparative Example 3:
[0153] Figure 8 is the SEM image of the metal organic framework in Example 11, Fig. 9 The SEM images of the metal organic framework in Example 5 (a) and Comparative Example 3 (b) are shown. Fig. 9 It can be seen that the metal organic framework prepared by the method provided by the present invention has uniform size; Fig. 9 It can be seen that the morphologies of the metal-organic framework HKUST-1-Ⅰ prepared in Example 5 and the conventional HKUST-1-Ⅱ prepared in Comparative Example 3 are quite different, indicating that when stearate is used as a metal precursor, the stearate can be used as a surfactant in the process of forming the metal-organic framework, which has a significant effect on the morphology of the metal-organic framework, and the metal-organic framework prepared by the method provided by the present invention has a smaller particle size.
[0154] 4. Conduct water contact angle test on the metal organic framework materials prepared in the examples and comparative examples:
[0155] Fig.10 Graphs showing water contact angles of the metal organic frameworks in Example 1(a) and Comparative Example 1(b), Fig.11 is the water contact angle diagram of the metal organic framework Zn-MOF-74 in Example 3, Fig.12 is the water contact angle diagram of the metal organic framework Zn-HKUST-1 in Example 4, Fig.13 is the water contact angle diagram of the metal organic framework HKUST-1-Ⅰ in Example 5, Fig.14 is the water contact angle diagram of the metal organic framework Mg-MOF-74 in Example 6, Fig.15 is the water contact angle diagram of the metal organic framework Fe-MIL-101 in Example 9, Fig.16 : is the water contact angle diagram of the metal organic framework ZIF-67-Ⅰ in Example 11. Fig.10 It can be seen that compared with ZIF-8-IV prepared with nitrate as a precursor in Comparative Example 1, ZIF-8-I prepared with stearate as a precursor in Example 1 has better hydrophobicity. Figure 11-Figure 16 It can be seen that the metal organic frameworks prepared by the method provided by the present invention have excellent hydrophobicity, which is beneficial to improving the water stability of the metal organic framework.
[0156] 5. Comparison of the catalytic synthesis performance of the metal organic frameworks in Example 5 and Comparative Example 3:
[0157] Fig.17 This is a performance comparison diagram of the metal organic framework catalyzing the synthesis of 2-phenylbenzimidazole in Example 5 and Comparative Example 3. The catalytic reaction route is shown as follows:
[0158]
[0159] Depend on Fig.17It can be seen that the hydrophobic metal organic framework HKUST-1-Ⅰ prepared in Example 5 has a higher catalytic synthesis efficiency than the conventional HKUST-1-Ⅱ prepared in Comparative Example 3, and the secondary catalytic synthesis efficiency HKUST-1-Ⅰ after recovery is significantly higher than HKUST-1-Ⅱ, that is, when the metal organic framework material prepared by the method provided by the present invention is applied to the catalytic field, the catalytic efficiency is high and the cycle stability is good. This is mainly because the hydrophobic HKUST-1-Ⅰ in Example 5 has better stability to water during the aqueous phase catalysis, and can maintain the original structure and performance after catalysis, while the conventional HKUST-1-Ⅱ in Comparative Example 3 has poor stability to water, and part of the structure is destroyed after catalysis, resulting in a significant decrease in catalytic performance.
[0160] The preparation method of the metal organic framework provided by the present invention, using metal soap salt (such as stearate) as a metal source, can realize one-step synthesis of super hydrophobic metal organic framework materials, the material end group has functional groups such as soap groups for end-capping, saturated aliphatic long chains extend outward, realize the construction of super hydrophobic surface, can realize the improvement of water stability and self-cleaning effect, can significantly improve the water phase catalytic performance of materials. The anion of metal soap salt can be used as a surfactant to regulate the morphology and particle size of the metal organic framework, compared with conventional metal organic framework materials of the same type, the size of the material is uniform and the particle size is smaller, and this method will not affect the surface pore structure of the material, for increasing the specific surface area of the material, improving the adsorption and other properties of the material has a positive effect. The present invention provides a method under the premise of existing metal soap salts, can realize the full class preparation of existing metal organic frameworks including ZIF-8, HKUST-1, UiO-66, etc., the method has strong applicability and good practicality.
Claims
1. A method for preparing a hydrophobic metal organic framework, characterized in that: The following steps are involved: S1, dissolving the metal soap salt and the organic ligand in an organic solvent respectively to obtain a metal soap salt solution and an organic ligand solution; S2, adding the organic ligand solution dropwise to the metal soap salt solution to react and obtain the hydrophobic metal organic framework.
2. The preparation method according to claim 1, characterized in that: In the step S1, the metal soap salt includes stearate.
3. The preparation method according to claim 1, characterized in that: In the step S1, the organic ligand is selected from at least one of benzimidazole, imidazole, 2-methylimidazole, terephthalic acid, 2-aminoterephthalic acid, 2,5-hydroxyterephthalic acid, isophthalic acid, phthalic acid, trimesic acid, trimellitic acid and their derivatives.
4. The preparation method according to claim 1, characterized in that: In the step S1, the organic solvent is selected from at least one of methanol, ethanol, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.
5. The preparation method according to claim 1, characterized in that: In the step S1, the metal soap salt and the organic ligand are dissolved in the same organic solvent; Preferably, the concentration ratio of the metal soap salt solution to the organic ligand solution is (0.125-2):
1.
6. The preparation method according to claim 5, characterized in that: The concentration of the metal soap salt solution is 0.01-1 mol / L; And / or, the concentration of the organic ligand solution is 0.01-1 mol / L.
7. The preparation method according to claim 1, characterized in that: In the step S2, the volume ratio of the organic ligand solution to the metal soap salt solution is 1:(0.8-1.2).
8. The preparation method according to claim 1, characterized in that: In the step S2, the reaction temperature is 70-150° C. and the reaction time is 0.1-24 h.
9. A hydrophobic metal organic framework obtained by the preparation method according to any one of claims 1 to 8.
10. Use of the hydrophobic metal organic framework according to claim 9 in the field of gas storage and separation, or catalysis.