A dual-ligand microporous / mesoporous / macroporous metal-organic framework material and a preparation method thereof

Abstract

The application discloses a kind of dual-ligand microporous / mesoporous / macroporous metal organic framework materials and preparation method thereof, belong to metal organic framework material technical field, the method realizes the organic integration of structural complexity and multistage pore characteristics in single MOF nanostructure by multi-component synergistic assembly strategy, and synthesizes dual-ligand multistage pore MOF nanospheres;By regulating the structure of functional ligand or changing the synthesis medium, it can be further extended to the preparation of a variety of dual-ligand mediated microporous / mesoporous / macroporous synergistic configuration metal organic framework materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal organic framework materials, and particularly relates to a kind of bidentate microporous / mesoporous / macroporous metal organic framework material and a preparation method thereof. BACKGROUND

[0002] Metal-Organic Frameworks (MOFs) are a class of highly ordered porous crystalline materials formed by metal ions / clusters and organic ligands through coordination bonds. Due to their high specific surface area, rich pore structure, good designability, and potential for multifunctionalization, MOFs have attracted widespread attention in recent years in the fields of gas adsorption and separation, catalysis, sensing, drug release, energy storage and conversion, etc. MIL-101, as a typical representative of the MOF family, has become one of the first MOFs to achieve industrialization and application research due to its excellent thermal stability, catalytically active centers derived from metals or ligands, intrinsic mesoporous channels, and good chemical stability. Although MIL-101 has certain advantages in many aspects, most of its conventional synthesis routes use a single organic ligand system, which often makes it difficult to form more complex structural hierarchies or further introduce other functional sites. At the same time, the traditional MIL-101 crystal mesoporous channels are small, which leads to some deficiencies in its practical applications. In summary, the traditional MIL-101 has the following problems: (1) single function, lack of further site engineering space, difficult to meet the needs of cooperative function in complex systems; (2) high specific surface area, but limited pore flux, low molecular diffusion efficiency, especially for large molecule substrate transport.

[0003] In recent years, by introducing a small amount of functional ligands based on the main ligand (such as BDC) to construct a dual-ligand system, it has been proven to effectively regulate the skeleton structure and local chemical environment of MOFs, which not only helps to introduce specific functional sites, but also to a certain extent, affects the growth behavior and morphology evolution of the crystal. At the same time, the construction of multi-level pore MOF structures with microporous, mesoporous, and macroporous coexisting has gradually become a research hotspot. Such structures can significantly improve the molecular transport efficiency and enhance the contact probability of reactants and active sites, thereby improving the performance of MOFs in catalysis, adsorption, and other processes. Among them, using surfactant template method to regulate the crystallization process of MOFs is an effective means to construct multi-level pore structures.

[0004] Currently, research on the construction of MIL-101 nanospheres with hierarchical porous structures under surfactant-induced synthesis remains limited, particularly in terms of preparation methods for achieving morphology control, synergistic regulation of pore structure, and fine-tuning of framework properties using dual ligands. Therefore, there is an urgent need to develop a simple, controllable, and versatile synthetic strategy, combined with dual-ligand regulation, to achieve the controllable synthesis of multifunctional microporous / mesoporous / macroporous MIL-101 nanospheres, meeting their high-efficiency application requirements in heterogeneous catalysis, adsorption separation, and other fields. Summary of the Invention

[0005] To address the shortcomings of existing technologies in the synthesis of hierarchical porous MIL-101 nanospheres based on surfactant-induced synthesis, such as the immaturity of synthesis strategies for finely adjusting framework composition, pore size distribution, or functional sites, and the lack of universal and controllable synthesis strategies, this invention provides a dual-ligand microporous / mesoporous / macroporous metal-organic framework material and its preparation method. This method achieves the organic integration of structural complexity and hierarchical pore characteristics within a single MOF nanostructure through a multi-component synergistic assembly strategy, synthesizing dual-ligand hierarchical porous MOF nanospheres. By controlling the structure of functionalized ligands or changing the synthesis medium, this method can be further extended to the preparation of various dual-ligand-mediated microporous / mesoporous / macroporous synergistic configuration metal-organic framework materials.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material specifically includes the following steps:

[0008] Step 1: Dissolve the surfactants disodium cocoamphodiacetate (CAD), F127, and P123 in deionized water and mix them by sonication to obtain a clear solution;

[0009] Step 2: Add glycerol and organic solvent to the clear solution from Step 1, and mix by sonication to obtain mixed solution A;

[0010] Step 3: Add ferric nitrate nonahydrate, the main ligand, and the functionalized ligand to the mixed solution A obtained in Step 2 in a certain mass ratio to obtain mixed solution B;

[0011] Step 4: Stir the mixed solution B obtained in Step 3 at 55 °C. After the reaction is complete, centrifuge, wash, and dry to obtain a dual-ligand microporous / mesoporous / macroporous metal-organic framework material.

[0012] Further, in step one, the mass ratio of CAD, F127, and P123 is 1:5:5; the mass percentage of F127 in the clear solution is 0.1-0.5 w.

[0013] Further, in step two, the organic solvent is one or more of TMB and cyclohexane.

[0014] Further, in step three, the main ligand is terephthalic acid, and the functional ligand is 2,5-dimercaptoterephthalic acid, sulfonic acid group terephthalic acid, hydroxy terephthalic acid or nitro terephthalic acid.

[0015] Further, in step three, the molar ratio of the iron nitrate nonahydrate, the main ligand and the functional ligand is 5:5:1, and the molar concentration of the iron nitrate nonahydrate in the mixed solution B is 5-60 mM.

[0016] Further, in step four, the stirring rate is 200-700 rpm, the reaction time is 5 h, the centrifugal speed is 8000 rpm, the time is 3 min, the washing solvent is DMF and ethanol, and the drying temperature is 60℃.

[0017] In another aspect, the application also provides a dual-ligand microporous / mesoporous / macroporous metal organic framework material, which is prepared by the above method.

[0018] Further, the material has a multi-level pore structure of micropores, mesopores and macropores, the mesopores are highly open channels diverging from the center to the periphery, and the macropores are "gully" structures.

[0019] Compared with the prior art, the application has the following advantages:

[0020] 1. The application first uses a surfactant template method to realize the controllable synthesis of multi-level pore iron-based MIL-101(Fe) nanospheres, effectively breaking through the limitations of traditional synthesis strategies on morphology and pore structure control, and the obtained material has micropores, mesopores and macropores, significantly improving the diffusion efficiency of molecules in the material, solving the problem that traditional MOFs are easily limited by diffusion in application, and being especially suitable for catalytic conversion and efficient adsorption separation process of macromolecular substrates;

[0021] 2. The application constructs the MOF framework by the functional ligand and the main ligand terephthalic acid, not only enhances the framework stability, but also introduces rich chemical functional sites in the framework, providing a highly adjustable platform for subsequent metal loading, catalytic reaction or targeted adsorption;

[0022] 3. The main ligand and the functional ligand can be flexibly replaced according to the target application, providing a highly flexible platform method for constructing multifunctional and multi-level pore MOF materials. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings required to be used in the specific embodiments or prior art description will be briefly introduced below.

[0024] Figure 1 Synthesis scheme of DL-micro- / meso- / macro MIL-101 NSs synthesized for Example 1;

[0025] Figure 2 Scanning and transmission pictures of DL-micro- / meso- / macro MIL-101 NSs synthesized for Example 1;

[0026] Wherein, a is a low-magnification scanning picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, b is a single scanning picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, c is a high-magnification scanning picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, d is a low-magnification transmission picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, e is a single transmission picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, f is a high-magnification transmission picture of the synthesized DL-micro- / meso- / macro MIL-101 NSs, and g is a scanning transmission electron microscope (STEM) image and C, Fe and O element distribution image of the synthesized DL-micro- / meso- / macro MIL-101 NSs;

[0027] Figure 3 X-ray photoelectron spectroscopy (XPS) of DL-micro- / meso- / macro MIL-101 NSs synthesized for Example 1;

[0028] Figure 4 X-ray diffraction spectrum of DL-micro- / meso- / macro MIL-101 NSs synthesized for Example 1 and traditional microporous control sample MicroMIL-101;

[0029] Figure 5 Nitrogen adsorption and pore size distribution spectrum of DL-micro- / meso- / macro MIL-101 NSs synthesized for Example 1 and traditional microporous control sample MicroMIL-101;

[0030] Wherein, a is the nitrogen adsorption spectrum of the synthesized DL-micro- / meso- / macroMIL-101 NSs and the conventional microporous control sample MicroMIL-101; b is the pore size distribution spectrum of the synthesized DL-micro- / meso- / macroMIL-101 NSs and the conventional microporous control sample MicroMIL-101.

[0031] Figure 6 Thermogravimetric analysis (TGA) curves of DL-micro- / meso- / macroMIL-101 NSs and the conventional microporous control sample MicroMIL-101 were obtained;

[0032] Figure 7 The graph shows the changes when the incorporation of three surfactants is altered.

[0033] Wherein, a is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs, b is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs without CAD, c is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs without P123, d is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs without F27, e is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs, f is a single transmission image of the synthesized DL-micro- / meso- / macroMIL-101 NSs without CAD, and g is a single scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs. A single transmission image of NSs without P123, h is a single transmission image of synthesized DL-micro- / meso- / macroMIL-101 NSs without F27;

[0034] Figure 8 The scanning, transmission, XRD and FT-IR spectra of DL-micro- / meso- / macroMIL-101 NSs (SO3Na) synthesized in Example 2 are shown.

[0035] wherein, a is the low-magnification scanning image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na), b is the high-magnification scanning image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na), c is the low-magnification transmission image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na), d is the high-magnification transmission image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na), e is the XRD spectrum of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na), and f is the FT-IR spectrum of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na); Figure 9 Scanning, transmission, XRD and FT-IR spectra of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH) of Example 3;

[0036] wherein, a is the low-magnification scanning image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH), b is the high-magnification scanning image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH), c is the low-magnification transmission image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH), d is the high-magnification transmission image of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH), e is the XRD spectrum of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH), and f is the FT-IR spectrum of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH); Figure 10 Scanning, transmission, XRD and FT-IR spectra of the synthesized DL-micro- / meso- / macro MIL-101 NSs (NO2) of Example 4;

[0037] In the image, a is a low-magnification scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2), b is a high-magnification scan image of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2), c is a low-magnification transmission image of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2), d is a high-magnification transmission image of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2), e is the XRD pattern of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2), and f is the FT-IR pattern of the synthesized DL-micro- / meso- / macroMIL-101 NSs(NO2). Detailed Implementation

[0038] To clearly and completely describe the technical solution and its specific working process of the present invention, the specific embodiments of the present invention are as follows, in conjunction with the accompanying drawings:

[0039] Example 1

[0040] This embodiment provides a method for preparing dual-ligand microporous / mesoporous / macroporous metal-organic framework materials, which specifically includes the following steps:

[0041] 5 mg of CAD, 50 mg of F127, and 50 mg of P123 were dissolved in 11.85 mL of deionized water, followed by the addition of 75 μL of TMB, 75 μL of cyclohexane, and 0.15 g of glycerol. The mixture was sonicated to form a homogeneous solution. Then, 107 mg of Fe(NO3)3·9H2O, 44 mg of BDC, and 1 mg of 2,5-dimercaptoterephthalic acid were added sequentially to this mixture, and the mixture was stirred at 55 °C for 5 hours. The resulting product was collected by centrifugation and washed three times with DMF and ethanol, respectively. The thoroughly washed product was dried under vacuum at 60 °C overnight to obtain DL-micro- / meso- / macroMIL-101 NSs.

[0042] like Figure 2 As shown in the scanning, transmission, and scanning transmission electron microscopy (STEM) images and elemental distribution images, the DL-micro- / meso- / macroMIL-101 NSs synthesized in Example 1 have highly open mesoporous channels that radiate outward from the center, and also have "groove"-shaped macropores.

[0043] like Figure 3For the X-ray photoelectron spectroscopy (XPS) of the DL-micro- / meso- / macro MIL-101 NSs synthesized in Example 1, the characteristic peak of sulfur (S) element was obviously detected in the full spectrum. The appearance of the peak indicated that the sulfur element was successfully doped or introduced into the structure of the MIL-101 nanosheets;

[0044] As shown in Figure 4 The X-ray diffraction spectra of the DL-micro- / meso- / macro MIL-101 NSs synthesized in Example 1 and the traditional microporous control sample Micro MIL-101 revealed that they were MIL-101 crystal structures, and had good crystallinity;

[0045] As shown in Figure 5 The nitrogen adsorption and pore size distribution spectra of the DL-micro- / meso- / macro MIL-101 NSs synthesized in Example 1 and the traditional microporous control sample Micro MIL-101 showed that there were abundant mesoporous structures in the DL-micro- / meso- / macro MIL-101 NSs;

[0046] As shown in Figure 6 The thermogravimetric analysis (TGA) curves of the DL-micro- / meso- / macro MIL-101 NSs and the traditional microporous control sample Micro MIL-101 showed that after removing the template, the DL-micro- / meso- / macro MIL-101 NSs would form certain structural defects in the framework of the material;

[0047] As shown in Figure 7 The scanning and transmission pictures of the change of the incorporation of the three surfactants were shown. It can be seen that when F127 was not added, the PPO proportion of P123 was high, the assembly parameter was 1 / 3 < P < 1 / 2, and dendritic micelles were formed. When P123 was not added, the hydrophilic PEO proportion of F127 was high, the assembly parameter P value was small (P < 1 / 3), the interfacial tension was large, and spherical micelles were easily formed. The introduction of the ionic surfactant CAD caused the charge interaction and local interface distortion, so that the original regular micelle template arrangement or interface deposition process was directionally twisted, fused or locally collapsed, thereby causing the formation of "gully" large pores or structural grooves. In the P123 plus ionic surfactant system, due to the serious disturbance of the coordination process, only amorphous or non-crystalline structures could be formed.

[0048] Example 2

[0049] The embodiment provides a preparation method of a dual-ligand micro-pore / meso-pore / macro-pore metal organic framework material, and the preparation method is to replace mercaptoterephthalic acid with sulfonic acid group terephthalic acid to synthesize DL-micro- / meso- / macro MIL-101 NSs (SO3Na), and specifically comprises the following steps:

[0050] 5mg of CAD, 50mg of F127 and 50mg of P123 are dissolved in 11.85mL of deionized water, then 75μL of TMB, 75μL of cyclohexane and 0.15g of glycerol are added, and ultrasonic is used to form a uniform solution. Then 107mg of Fe(NO3)3·9H2O, 44mg of BDC and 1mg of sulfonic acid group terephthalic acid are sequentially added to the mixed system, and stirring reaction is carried out at 55°C for 5 hours. The obtained product is collected by centrifugation, and is washed with DMF and ethanol respectively for three times. The thoroughly cleaned product is dried at 60°C under vacuum overnight, and DL-micro- / meso- / macro MIL-101 NSs (SO3Na) is obtained.

[0051] Figure 8 The scanning, transmission, XRD and FT-IR spectra of the synthesized DL-micro- / meso- / macro MIL-101 NSs (SO3Na) are shown in the figure, and it can be seen from the figure that the material still has good crystallinity while retaining the multi-level pore nanostructure characteristics, and the sulfonic acid group functional ligand is successfully introduced into the MIL-101 framework.

[0052] Embodiment 3

[0053] The embodiment provides a preparation method of a dual-ligand micro-pore / meso-pore / macro-pore metal organic framework material, and the preparation method is to replace mercaptoterephthalic acid with sulfonic acid group terephthalic acid to synthesize DL-micro- / meso- / macro MIL-101 NSs (SO3Na), and specifically comprises the following steps:

[0054] 5mg of CAD, 50mg of F127 and 50mg of P123 are dissolved in 11.85mL of deionized water, then 75μL of TMB, 75μL of cyclohexane and 0.15g of glycerol are added, and ultrasonic is used to form a uniform solution. Then 107mg of Fe(NO3)3·9H2O, 44mg of BDC and 1mg of sulfonic acid group terephthalic acid are sequentially added to the mixed system, and stirring reaction is carried out at 55°C for 5 hours. The obtained product is collected by centrifugation, and is washed with DMF and ethanol respectively for three times. The thoroughly cleaned product is dried at 60°C under vacuum overnight, and DL-micro- / meso- / macro MIL-101 NSs (SO3Na) is obtained.

[0055] Figure 9The scanning, transmission, XRD and FT-IR spectra of the synthesized DL-micro- / meso- / macro MIL-101 NSs (OH) can be seen from the figures, and the material still has good crystallinity while retaining the hierarchical pore nanostructure characteristics, and the hydroxyl functional ligand is successfully introduced into the MIL-101 framework.

[0056] Example 4

[0057] The present embodiment provides a preparation method of a dual-ligand micro- / meso- / macro metal-organic framework material, which synthesizes DL-micro- / meso- / macro MIL-101 NSs (NO2) by replacing mercaptoterephthalic acid with nitroterephthalic acid, and specifically includes the following steps:

[0058] 5 mg of CAD, 50 mg of F127 and 50 mg of P123 are dissolved in 11.85 mL of deionized water, followed by adding 75 μL of TMB, 75 μL of cyclohexane and 0.15 g of glycerol, and ultrasonicating to form a uniform solution. Then 107 mg of Fe(NO3)3·9H2O, 44 mg of BDC and 1 mg of nitroterephthalic acid are sequentially added to the mixed system, and the reaction is stirred at 55°C for 5 hours. The obtained product is collected by centrifugation and washed with DMF and ethanol three times, respectively. The thoroughly cleaned product is dried at 60°C under vacuum overnight to obtain DL-micro- / meso- / macro MIL-101 NSs (NO2);

[0059] Figure 10 The scanning, transmission, XRD and FT-IR spectra of the synthesized DL-micro- / meso- / macro MIL-101 NSs (NO2) can be seen from the figures, and the material still has good crystallinity while retaining the hierarchical pore nanostructure characteristics, and the nitro functional ligand is successfully introduced into the MIL-101 framework.

[0060] The preferred embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0061] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combination manners.

[0062] Furthermore, the various embodiments of the present application can be combined with each other, as long as it does not violate the spirit of the present application, and it should be considered as disclosed in the present application.

Claims

1. A method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material, characterized in that, Specifically, the steps include the following: Step 1: Dissolve the surfactants disodium cocoamphodiacetate (CAD), F127, and P123 in deionized water and mix them by sonication to obtain a clear solution; Step 2: Add glycerol and organic solvent to the clear solution from Step 1, and mix by sonication to obtain mixed solution A; Step 3: Add ferric nitrate nonahydrate, the main ligand, and the functionalized ligand to the mixed solution A obtained in Step 2 in a certain mass ratio to obtain mixed solution B; Step 4: Stir the mixed solution B obtained in Step 3 at 55°C. After the reaction is complete, centrifuge, wash, and dry to obtain a dual-ligand microporous / mesoporous / macroporous metal-organic framework material. In step one, the mass ratio of CAD, F127, and P123 is 1:5:5; the mass percentage of F127 in the clear solution is 0.1-0.5 wt%.

2. The method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material as described in claim 1, characterized in that, In step two, the organic solvent is one or more of TMB and cyclohexane.

3. The method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material as described in claim 1, characterized in that, In step three, the main ligand is terephthalic acid, and the functionalized ligand is 2,5-dimercaptoterephthalic acid, sulfonic acid terephthalic acid, hydroxyterephthalic acid, or nitroterephthalic acid.

4. The method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material as described in claim 1, characterized in that, In step three, the molar ratio of ferric nitrate nonahydrate, the main ligand, and the functionalized ligand is 5:5:1; the molar concentration of ferric nitrate nonahydrate in mixed solution B is 5-60 mM.

5. The method for preparing a dual-ligand microporous / mesoporous / macroporous metal-organic framework material as described in claim 1, characterized in that, In step four, the stirring rate is 200-700 rpm, the reaction time is 5 h, the centrifugation speed is 8000 rpm, the time is 3 min, the washing solvent is DMF and ethanol, and the drying temperature is 60℃.

6. A dual-ligand microporous / mesoporous / macroporous metal-organic framework material, characterized in that, Prepared by the method described in any one of claims 1-5.

7. A dual-ligand microporous / mesoporous / macroporous metal-organic framework material as described in claim 6, characterized in that, The material has a multi-level pore structure of micropores, mesopores and macropores, wherein the mesopores are highly open channels radiating from the center to the surrounding area, and the macropores are "groove"-like structures.

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