A binuclear iron-based metal-organic framework material and its preparation method and application
By preparing the dual-core iron-based metal-organic framework material of [Fe2(BPTC)(DMSO)2] in a specific solvent system by using solvothermal method, the problems of limited preparation methods and insufficient adsorption performance are solved, and efficient gas separation performance is achieved.
Patent Information
- Application Number
- CN202310709990.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-15
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2043-06-15
AI Technical Summary
The existing preparation methods for dual-core iron-based metal-organic framework materials are relatively limited, and the stability and adsorption performance are insufficient, making it difficult to achieve efficient gas separation.
Ferrous chloride tetrahydrate and 3,3’,5,5’-biphenyltetracarboxylic acid were prepared by solvothermal method in a mixed solvent system of N,N-dimethylacetamide, dimethyl sulfoxide and tetrafluoroboric acid. [Fe2(BPTC)(DMSO)2].
The efficient preparation of dual-core iron-based metal-organic framework materials is achieved. The material has rich open metal sites and porous structures, which significantly improves the adsorption amount of C2H2 and CO2 and the exclusion ability of CH4, which is better than the reported tri-core cluster-based Fe-MOFs materials.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of alkane adsorption and separation, and specifically relates to a binuclear iron-based metal-organic framework material with biphenyltetracarboxylic acid as an organic ligand, and a preparation method and application thereof. Background Art
[0002] Metal-Organic Frameworks (MOFs), as a new type of adsorbent, are a type of crystalline porous crystalline material self-assembled by metal ions or metal clusters and organic ligands through coordination bonds. Due to its advantages such as ultra-high specific surface area, structural designability, and pore modifiability, it has great application potential in gas storage. At present, MOF materials with better separation performance are mostly concentrated in Zn / Cu-MOFs with relatively low stability, and there are very few stable MOF materials that can achieve high efficiency and high adsorption performance. At present, there are very few reports on binuclear iron-based metal-organic framework materials. The main reason is that iron salts tend to form stable iron hydroxides or oxides, and cannot self-assemble with organic ligands to form crystalline materials.
[0003] Through literature research (Chem. Eur. J., 2017, 23, 6693 – 6700) found that under the solvothermal conditions of N,N-dimethylacetamide (1 mL), dimethyl sulfoxide (3 mL) and tetrafluoroboric acid solvent system (7 drops), we successfully constructed a trinuclear cluster-based Fe-MOFs (SNNU-60) based on the organic ligand 3,3',5,5'-biphenyltetracarboxylic acid (H4BPTC). This trinuclear secondary building block consists of a μ3-OH - ions, three Fe 2+ ions, three coordinated dimethyl sulfoxide molecules and six carboxyl oxygens from different ligands. Gas adsorption performance studies revealed that this MOF material exhibited good methane purification capabilities. However, among the many reported methane purification MOFs materials, binuclear secondary structural units have a great advantage. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a new type of porous binuclear iron-based metal-organic framework material and to provide an effective preparation method for the Fe-MOF material.
[0005] The binuclear iron-based metal-organic framework material of the present invention has a chemical formula of [Fe2(BPTC)(DMSO)2], BPTC 4- It is a 3,3',5,5'-biphenyltetracarboxylic acid anion with the hydrogen atoms on the four carboxyl groups removed.
[0006] Single X-ray crystal structure analysis shows that the crystal structure of the binuclear iron-based metal-organic framework material (Fe-MOF material) belongs to the trigonal system, the space group is R-3m, and the unit cell parameters are: α=β=90°, γ=120°.
[0007] In this metal-organic framework material, binuclear iron-based secondary building units (Fe-SBUs) consist of two Fe 2+ ions, two coordinating solvent molecules dimethyl sulfoxide and four carboxyl oxygens from different ligands. At the same time, the organic ligand BPTC 4- Four Fe-SBUs are connected to form a three-dimensional porous structure. The structure has two different pore sizes ( and ) one-dimensional cylinder. From a topological point of view, each Fe-SBUs can act as a 4-connected node, and the organic ligand BPTC 4- As a 4-connected node, a single-node 4-connected NbO topology is formed, and its topology conforms to {6 4 .8 2}.
[0008] The invention discloses a method for preparing a binuclear iron-based metal-organic framework material based on biphenyltetracarboxylic acid, comprising the following steps: adding ferrous chloride tetrahydrate and an organic ligand 3,3',5,5'-biphenyltetracarboxylic acid H4BPTC into a mixed solvent system of N,N-dimethylacetamide, dimethyl sulfoxide and tetrafluoroboric acid to obtain a mixed solution, performing a solvent thermal reaction, and naturally cooling to room temperature after the reaction is completed to obtain a binuclear iron-based metal-organic framework material.
[0009] Furthermore, the structural formula of the organic ligand 3,3',5,5'-biphenyltetracarboxylic acid H4BPTC is as follows:
[0010]
[0011] Furthermore, in the mixed solution, the concentration of ferrous chloride tetrahydrate is 0.02-0.045 mol / L, and the concentration of the organic ligand 3,3',5,5'-biphenyltetracarboxylic acid H4BPTC is 0.004-0.0065 mol / L.
[0012] Furthermore, the volume ratio of N,N-dimethylacetamide, dimethyl sulfoxide and tetrafluoroboric acid in the mixed solvent is (6-8):(1-2):(0.15-0.25).
[0013] Furthermore, the temperature of the solvent thermal reaction is 130° C., and the reaction is kept at a constant temperature for 2 days.
[0014] The preparation method of the binuclear iron-based metal-organic framework material based on biphenyltetracarboxylic acid of the present invention is as follows:
[0015] Ferrous chloride tetrahydrate and organic ligand H4BPTC are added to a mixed solution system of N,N-dimethylacetamide (6mL-8mL), dimethyl sulfoxide (1mL-2mL) and tetrafluoroboric acid (0.15mL-0.25mL) in a molar ratio of (5-7):1 to carry out a solvothermal reaction. The solvothermal reaction temperature is 130°C and the reaction is kept at a constant temperature for 2 days, and then naturally cooled to room temperature to prepare a binuclear iron-based metal-organic framework material.
[0016] The present invention also provides an application of a binuclear iron-based metal-organic framework material based on biphenyltetracarboxylic acid. The binuclear iron-based metal-organic framework material of the biphenyltetracarboxylic acid of the present invention is used as a C2H2, CO2 and CH4 adsorption material, has high C2H2, CO2 adsorption capacity and low CH4 adsorption capacity, and its adsorption capacity ratios C2H2 / CH4 and CO2 / CH4 are higher than those of the reported tri-nuclear cluster-based Fe-MOFs (SNNU-60).
[0017] Compared with the prior art, the main advantages of the present invention include:
[0018] 1. The N,N-dimethylacetamide / dimethyl sulfoxide / tetrafluoroboric acid solvent system of the present invention is conducive to the growth of Fe-MOF crystalline materials, wherein dimethyl sulfoxide can be used as both a solvent and a coordinating solvent molecule in the MOF structure. The binuclear iron-based metal-organic framework material has abundant open metal sites and two different pore sizes ( and ), which can promote the efficient separation of C2H2 / CH4 and CO2 / CH4. By comparison, it is found that the methane purification performance of the binuclear iron-based metal-organic framework material is improved compared with the reported tri-nuclear cluster-based Fe-MOFs. , which is improved compared with the reported tri-nuclear cluster-based Fe-MOFs.
[0019] 2. The binuclear iron-based metal-organic framework material of the present invention is prepared by a solvothermal method, which is simple and universal. The prepared complex has high C2H2 and CO2 adsorption capacity and low CH4 adsorption capacity, and can be used as a potential methane gas purification material. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is the SEM morphology of the metal organic framework material prepared in Example 3.
[0021] Figure 2 This is a diagram of the binuclear iron cluster structure of the metal organic framework material prepared in Example 3.
[0022] Figure 3This is the organic ligand connection diagram of the metal organic framework material prepared in Example 3.
[0023] Figure 4 This is a three-dimensional structural diagram of the metal organic framework material prepared in Example 3 after removing dimethyl sulfoxide.
[0024] Figure 5 This is the X-ray powder diffraction pattern of the metal organic framework material Fe-MOF prepared in Example 3.
[0025] Figure 6 This is the C2H2, CO2 and CH4 gas adsorption diagram of the metal organic framework material prepared in Example 3 at 273K.
[0026] Figure 7 This is the C2H2, CO2 and CH4 gas adsorption diagram of the metal organic framework material at 298K in Example 3. DETAILED DESCRIPTION
[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.
[0028] Example 1
[0029] Take the preparation of tetrazole porous complex with structural unit [Fe2(BPTC)(DMSO)2] as an example, where BPTC 4- The 3,3',5,5'-biphenyltetracarboxylic acid anion is prepared by removing the hydrogen atoms on the four carboxyl groups. The specific preparation method is as follows:
[0030] Ferrous chloride tetrahydrate (0.31 mmol) and an organic ligand 3,3',5,5'-biphenyltetracarboxylic acid (0.045 mmol) were added to a mixed solution system of N,N-dimethylacetamide (6 mL), dimethyl sulfoxide (1 mL) and tetrafluoroboric acid (0.15 mL). The thermal reaction temperature was 130° C. and the reaction was kept at a constant temperature for 2 days. The reaction was naturally cooled to room temperature to prepare cubic crystals of a binuclear iron-based metal-organic framework material.
[0031] Example 2
[0032] The preparation method of the binuclear iron-based metal-organic framework material in this embodiment is as follows:
[0033] Ferrous chloride tetrahydrate (0.25 mmol) and an organic ligand 3,3',5,5'-biphenyltetracarboxylic acid (0.05 mmol) were added to a mixed solution system of N,N-dimethylacetamide (8 mL), dimethyl sulfoxide (2 mL) and tetrafluoroboric acid (0.20 mL). The thermal reaction temperature was 130° C. and the reaction was kept at a constant temperature for 2 days. The reaction was naturally cooled to room temperature to prepare cubic crystals of a binuclear iron-based metal-organic framework material.
[0034] Example 3
[0035] The preparation method of the binuclear iron-based metal-organic framework material in this embodiment is as follows:
[0036] Ferrous chloride tetrahydrate (0.31 mmol) and organic ligand 3,3',5,5'-biphenyltetracarboxylic acid (0.045 mmol) were added to a mixed solution system of N,N-dimethylacetamide (8 mL), dimethyl sulfoxide (2 mL) and tetrafluoroboric acid (0.25 mL). The temperature of the thermal reaction was 130° C. and the reaction was allowed to stand for 2 days. The reaction was then naturally cooled to room temperature to prepare cubic crystals of binuclear iron-based metal-organic framework materials ( Figure 1 ).
[0037] The test results of the products obtained in the above embodiments are the same, as shown below:
[0038] (1) Crystal structure determination:
[0039] Data were collected at 298 K using a Bruker D8 VENTURE PHOTON II single crystal diffractometer. Data were collected using a Cu-Kα ( ) target ray. The crystal structure was solved by direct method using SHELXTL program. First, the coordinates of all non-hydrogen atoms were determined by difference function method and least square method, and the positions of hydrogen atoms were obtained by theoretical hydrogenation method. Then, SHELXTL was used to refine the crystal structure. See the structure diagram for details. Figure 2 , Figure 3 and Figure 4 The crystallographic data are shown in Table 1.
[0040] Table 1 Crystallographic data of the metal-organic framework material
[0041]
[0042]
[0043] Figure 2 The structural diagram shows that in this metal-organic framework material, the binuclear iron-based secondary building unit (Fe-SBUs) consists of two Fe 2+ ion, two coordinating solvent molecules dimethyl sulfoxide and four carboxyl oxygen groups from different ligands
[0044] Figure 3 The structural diagram shows that in this metal-organic framework material, the organic ligand BPTC 4- Four Fe-SBUs were connected to form a three-dimensional porous structure.
[0045] Figure 4The structural diagram shows that the structure has two different pore sizes ( and ) is a one-dimensional cylinder.
[0046] Figure 5 The structural diagram shows that the diffraction peaks of the experimental powder PXRD spectrum and the single crystal structure simulation PXRD spectrum are basically consistent, indicating that the purity of the MOFs material is very high.
[0047] (2) Characterization of gas adsorption performance:
[0048] Figure 6 and Figure 7 The application of the material of the present invention in gas adsorption shows that at 273K under 1 atmosphere, the adsorption capacity of the metal-organic framework material for C2H2, CO2 and CH4 is 78.3, 64.1 and 9.2 cm2, respectively. 3 g -1 ( Figure 6 ), at 298K, the adsorption capacities of C2H2, CO2 and CH4 are 45.8, 33.4 and 7.8 cm 3 g -1 ( Figure 7 ). Therefore, we found that the adsorption ratios of C2H2 / CH4 and CO2 / CH4 were 8.5 and 6.9 at 273K and 5.8 and 4.2 at 298K, which were higher than the corresponding values of SNNU-60 under the same conditions (273K, C2H2 / CH4=2.6 and CO2 / CH4=2.5; 273K, C2H2 / CH4=3.3 and CO2 / CH4=3.0).
Claims
1. A binuclear iron-based metal-organic framework material, characterized in that: The chemical formula of binuclear iron-based metal-organic framework material is [Fe2(BPTC)(DMSO)2], BPTC 4- The crystal structure of the binuclear iron-based metal-organic framework material belongs to the trigonal system, and the space group is R-3m , the unit cell parameters are: a = 19.1104(9) Å, b = 19.1104(9) Å, c = 24.504(2) Å, α = β = 90 o , γ = 120 o .
2. The binuclear iron-based metal-organic framework material according to claim 1, characterized in that: In binuclear iron-based metal-organic framework materials, the binuclear iron-based secondary building blocks Fe-SBUs consist of two Fe 2+ ions, two coordinating solvent molecules dimethyl sulfoxide and four carboxyl oxygens from different ligands. At the same time, the organic ligand BPTC 4- Four Fe-SBUs were connected to form a three-dimensional porous structure.
3. The method for preparing a binuclear iron-based metal-organic framework material according to claim 1, characterized in that: Add ferrous chloride tetrahydrate and organic ligand 3,3',5,5'-biphenyltetracarboxylic acid H4BPTC N , N - A mixed solution is obtained in a mixed solvent system of dimethylacetamide, dimethyl sulfoxide and tetrafluoroboric acid, and a solvothermal reaction is carried out. After the reaction is completed, the mixture is naturally cooled to room temperature to obtain a binuclear iron-based metal-organic framework material.
4. The method for preparing a binuclear iron-based metal-organic framework material according to claim 3, characterized in that: In the mixed solution, the concentration of ferrous chloride tetrahydrate is 0.02-0.045 mol / L, and the concentration of the organic ligand 3,3',5,5'-biphenyltetracarboxylic acid H4BPTC is 0.004-0.0065 mol / L.
5. The method for preparing a binuclear iron-based metal-organic framework material according to claim 3, characterized in that: The mixed solvent N , N -The volume ratio of dimethylacetamide, dimethyl sulfoxide and tetrafluoroboric acid is (6~8):(1~2):(0.15~0.25).
6. The method for preparing a binuclear iron-based metal-organic framework material according to claim 3, characterized in that: The temperature of the solvent thermal reaction is 130° C., and the reaction is kept at a constant temperature for 2 days.
7. The use of the binuclear iron-based metal-organic framework material in gas adsorption according to claim 1 or 2, characterized in that: The binuclear iron-based metal-organic framework material is used as a C2H2, CO2 and CH4 adsorption material.