Interpenetration type iron-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention discloses an interpenetrating type iron-based metal organic framework material and a preparation method and application thereof, the molecular formula of the material is [Fe3O4 (H2O) 3 (L1) (L2) 4 / 3], in the formula, L1 represents deprotonated 4-(4-carboxybenzamido) benzoic acid, L2 represents deprotonated 1, 3, 5-tri (4-carboxyphenyl) benzene, and n represents 1, 3, 5-tri (4-carboxyphenyl) benzene; the material belongs to a hexagonal crystal system and an R-3c space group, and is prepared by taking a trinuclear iron cluster, 4-(4-carboxybenzamido) benzoic acid and 1, 3, 5-tri (4-carboxyphenyl) benzene as raw materials, acetic acid as a template agent and N, N-dimethylformamide and n-amyl alcohol as solvents through solvothermal reaction. The interpenetrating type iron-based metal organic framework material disclosed by the invention has a relatively large specific surface area and a relatively large pore structure, has good adsorption performance on methane and carbon dioxide, and has a wide application prospect in the fields of methane storage and flue gas carbon dioxide capture.

Description

Technical Field

[0001] This invention belongs to the field of metal-organic framework materials technology, specifically relating to an interpenetrating iron-based metal-organic framework material, its preparation method, and its application. Background Technology

[0002] Metal-organic frameworks (MOFs) are a novel class of crystalline porous materials. They are three-dimensional network structures formed by the self-assembly of metal ions or metal clusters with organic ligands through coordination bonds. MOFs possess advantages such as controllable specific surface area, tunable pore size, modifiable pore surfaces, and well-defined structures, showing potential applications in energy gas storage, carbon capture and conversion, catalysis, and drug delivery. Therefore, they have attracted widespread attention from researchers over the past two decades. To date, tens of thousands of MOFs have been reported, and significant progress has been made in research on methane storage and carbon dioxide capture.

[0003] Iron-based organic frameworks are a new type of metal-organic framework material that has been developed in recent years. Due to the high valence state, high charge density, and strong polarizability of the central iron ion, trivalent iron exhibits a strong affinity for the carboxyl oxygen atom in the organic ligand. Since trivalent iron is a hard acid and the deprotonated carboxylic acid ligand is a hard base, according to the hard-soft acid-base theory, the resulting metal-organic framework compound exhibits good stability and has broad application prospects in gas storage and capture. Therefore, the structure and preparation of this type of material have attracted the attention of many research groups. Summary of the Invention

[0004] The purpose of this invention is to provide an example of an interpenetrating iron-based metal-organic framework material, and to provide a preparation method, activation method and application of the material.

[0005] To achieve the above objectives, the molecular formula of the intercalation-type iron-based metal-organic framework material provided by the present invention is [Fe3O(H2O)3(L1)(L2)]. 4 / 3 In the formula, L1 represents deprotonated 4-(4-carboxybenzoamide)benzoic acid, and L2 represents deprotonated 1,3,5-tris(4-carboxyphenyl)benzene; the crystal structure of this material belongs to the hexagonal crystal system, space group R-3c, with the following cell parameters: a=b=34.7425(17) Å, c=92.093(5) Å, α=β=90°, γ=120°, and the cell volume is 96267.4 Å. 3 .

[0006] The crystal structure of the interpenetrating iron-based metal-organic framework material of this invention contains two types of cages. One type of cage is an anti-triangular prism cage composed of 9 trinuclear iron clusters, 3 4-(4-carboxybenzoamide)benzoic acid ligands and 5 1,3,5-tris(4-carboxyphenyl)benzene ligands. The other type of cage is a flattened cubic octahedral cage composed of 6 trinuclear iron clusters, 6 4-(4-carboxybenzoamide)benzoic acid ligands and 12 1,3,5-tris(4-carboxyphenyl)benzene ligands.

[0007] The above-mentioned intercalation-type iron-based metal-organic framework material is prepared by mixing trinuclear iron cluster (Fe3O(CH3COO)6(H2O)3), 4-(4-carboxybenzoamide)benzoic acid, 1,3,5-tris(4-carboxyphenyl)benzene, N,N-dimethylformamide, acetic acid and n-pentanol evenly, and then heating and reacting at 125-135℃ for 24-48 hours under sealed conditions, and then cooling to room temperature to obtain the intercalation-type iron-based metal-organic framework material.

[0008] In the above preparation method, the preferred molar ratio of the trinuclear iron cluster to 4-(4-carboxybenzoamide)benzoic acid and 1,3,5-tris(4-carboxyphenyl)benzene is 1:2-3:1.1-1.5.

[0009] In the above preparation method, the preferred molar ratio of the trinuclear iron cluster to acetic acid is 1:80 to 150.

[0010] In the above preparation method, the volume ratio of N,N-dimethylformamide to n-pentanol is preferably 15-25:1.

[0011] The activation method of the interpenetrating iron-based metal-organic framework material of the present invention is as follows: first, acetone is used to exchange the material once every 20 to 60 minutes for a total of 3 to 5 times, and then hexane is used to exchange the material once every 20 to 60 minutes for a total of 3 to 5 times.

[0012] The interpenetrating iron-based metal-organic framework material activated by the above method has a large specific surface area and pore volume, and exhibits good adsorption performance for methane and carbon dioxide. It can be used for methane adsorption and storage and carbon dioxide capture in flue gas.

[0013] The beneficial effects of this invention are as follows:

[0014] 1. This invention uses a trinuclear iron cluster as the metal source, 4-(4-carboxybenzoamide)benzoic acid and 1,3,5-tris(4-carboxyphenyl)benzene as organic ligands, and acetic acid as a template agent to prepare an intercalated iron-based metal-organic framework material via a solvothermal reaction. The intercalated iron-based metal-organic framework material was activated with acetone and n-hexane. The nitrogen adsorption isotherm of the activated material at 77 K was tested, and the results showed that the activated material has a large specific surface area and pore volume of 2728 m².2 g -1 and 0.98 cm 3 g -1 This material has broad application prospects in the adsorption and storage of methane gas and the capture of carbon dioxide. 2. The high-pressure methane storage performance of the intercalated iron-based metal-organic framework material of this invention was tested. The results show that this material, due to its large pore volume and specific surface area, exhibits excellent performance in terms of mass ratio, exceeding that of Ni-MOF-74 under the same conditions. It also possesses a high volume ratio, especially under conditions of 273 K and 5–80 bar, where its mass ratio working capacity and volume ratio working capacity for methane are 0.147 g g and 0.147 g g, respectively. -1 139 cm 3 (STP) cm -3 It exhibits good performance in adsorbing methane. Furthermore, at 298 K and 1 bar, the separation selectivity for carbon dioxide and nitrogen, calculated based on the ideal adsorption solution theory, is 9.20 at a volume ratio of 15:85, indicating that the material has excellent carbon dioxide capture performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0016] Figure 2 This is a topological schematic diagram of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0017] Figure 3 This is a schematic diagram of the cage of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0018] Figure 4 This is a schematic diagram of the window of the intercalation iron-based metal-organic framework material prepared in Example 1.

[0019] Figure 5 These are powder X-ray diffraction patterns of the interpenetrating iron-based metal-organic framework material prepared in Example 1 before and after activation.

[0020] Figure 6 This is a powder X-ray diffraction pattern of the water stability of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0021] Figure 7 This is a thermal analysis diagram of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0022] Figure 8 This is a gas adsorption isotherm diagram of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0023] Figure 9This is a pore size distribution diagram of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0024] Figure 10 This is the high-pressure methane volume ratio adsorption isotherm of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0025] Figure 11 This is the high-pressure methane mass ratio adsorption isotherm of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0026] Figure 12 The carbon dioxide temperature-variable adsorption isotherm is the result of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0027] Figure 13 The nitrogen temperature-variable adsorption isotherm of the interpenetrating iron-based metal-organic framework material prepared in Example 1 is shown.

[0028] Figure 14 These are the carbon dioxide and nitrogen adsorption isotherms of the interpenetrating iron-based metal-organic framework material prepared in Example 1.

[0029] Figure 15 This is the IAST selectivity diagram of the interpenetrating iron-based metal-organic framework material prepared in Example 1. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0031] Example 1

[0032] 10 mg (0.017 mmol) of trinuclear iron cluster (Fe3O(CH3COO)6(H2O)3), 11 mg (0.039 mmol) of 4-(4-carboxybenzoamide)benzoic acid, 10 mg (0.023 mmol) of 1,3,5-tris(4-carboxyphenyl)benzene, 2 mL of N,N-dimethylformamide, 0.08 mL (1.40 mmol) of acetic acid, and 0.1 mL of n-pentanol were mixed thoroughly and added to a 20 mL scintillation flask. The flask was sealed and placed in an oven at 130 °C for 36 hours. After cooling to room temperature, dark brown polyhedral blocky crystals were obtained, which are interpenetrating iron-based metal-organic framework materials.

[0033] The structure of the interpenetrating iron-based metal-organic framework material prepared in Example 1 was characterized by single-crystal X-ray diffraction, and its molecular formula is [Fe3O(H2O)3(L1)(L2). 4 / 3In the formula, L1 represents deprotonated 4-(4-carboxybenzoamide)benzoic acid, and L2 represents deprotonated 1,3,5-tris(4-carboxyphenyl)benzene; the crystal structure of this material belongs to the hexagonal crystal system, space group R-3c, with the following cell parameters: a=b=34.7425(17) Å, c=92.093(5) Å, α=β=90°, γ=120°, and the cell volume is 96267.4 Å. 3 In its crystal structure, the inorganic molecular building block is a trinuclear iron cluster [Fe3O(H2O)3(O2C-)6]. Each [Fe3O(H2O)3(O2C-)6] oxygen-core trinuclear iron cluster is in a 6-linked state, and the ligands linked to it include two deprotonated 4-(4-carboxybenzoamide)benzoic acids and four deprotonated 1,3,5-tris(4-carboxyphenyl)benzene. These three are interconnected to form a three-dimensional periodic network structure with double interpenetration. Using the nodal method, the oxygen-core trinuclear iron cluster is simplified to a 6-linked node, 4-(4-carboxybenzoamide)benzoic acid is simplified to a 2-linked bar, and 1,3,5-tris(4-carboxyphenyl)benzene is simplified to a 3-linked node. Topological analysis shows that the structure is a 3,3,6-linked network, and the Schleifli notation is [3·4 2 5 3 7 5 8 4 ]3[4·5 2 ]3[4 3 ],See Figure 1 , 2 The material has a crystal structure with two types of cages. One cage (cage 1) is an anti-triangular prism cage composed of 9 trinuclear iron clusters, 3 4-(4-carboxybenzoamide)benzoic acid ligands, and 5 1,3,5-tris(4-carboxyphenyl)benzene ligands. The other cage (cage 2) is a flattened cubic octahedral cage composed of 6 trinuclear iron clusters, 6 4-(4-carboxybenzoamide)benzoic acid ligands, and 12 1,3,5-tris(4-carboxyphenyl)benzene ligands. Furthermore, each anti-triangular prism cage is surrounded by 4 cubic octahedral cages and 4 anti-triangular prism cages, and each cubic octahedral cage is surrounded by 6 anti-triangular prism cages. Cage 1 has a size of 13.5 Å, and cage 2 has a size of 5.0 × 26.4 Å. 2 ,like Figure 3As shown. Simultaneously, two types of windows exist in this crystal structure: one window (window 1) is an equilateral triangle composed of three trinuclear iron clusters and three 4-(4-carboxybenzoamide)benzoic acid ligands; the other window (window 2) is an isosceles triangle composed of three trinuclear iron clusters, one 4-(4-carboxybenzoamide)benzoic acid ligand, and two 1,3,5-tris(4-carboxyphenyl)benzene ligands. The size of window 1 is 7.88 Å, and the size of window 2 is 9.06 Å. Figure 4 As shown.

[0034] The interpenetrating iron-based metal-organic framework material prepared in Example 1 was first exchanged with acetone once every 1 hour for a total of 3 times, and then with n-hexane once every 1 hour for a total of 3 times. The material before and after activation was characterized. Figure 5 The results show that the positions of the diffraction peaks in the powder X-ray diffraction pattern of the obtained intercalated iron-based metal-organic framework material (compound 1 in the figure) after activation are completely consistent with the positions of the diffraction peaks in the powder X-ray diffraction pattern simulated by the structural data obtained by single-crystal structure analysis. This indicates that the single-crystal structure measured by X-ray diffractometer can well describe the material structure. It also shows that the present invention can prepare a large number of pure-phase intercalated iron-based metal-organic framework materials. After exchanging with acetone and n-hexane, its structure remains intact and is a pure phase.

[0035] The interpenetrating iron-based metal-organic framework material prepared in Example 1 was immersed in water for 24 hours, and powder X-ray diffraction tests were performed on the material before and after immersion. Figure 6 The results show that the material remains a pure phase after 24 hours of soaking, indicating that it has good water stability.

[0036] Thermal analysis was performed on the activated intercalation-type iron-based metal-organic framework material. Figure 7 This indicates that the frame only begins to collapse when the temperature reaches above 400℃, demonstrating its good thermal stability.

[0037] To confirm the porosity of the obtained intercalated iron-based metal-organic framework material, N2 adsorption isotherms were tested at 77 K, yielding a typical "I"-type curve (see...). Figure 8 This proves that it is a microporous material, with an N2 adsorption capacity of 583 cm⁻¹. 3 g -1 BET has a specific surface area of ​​2178 m². 2 g -1 The pore volume is 0.98 cm³. 3 g -1 .from Figure 9 It can be seen from this that the pore size in this material is approximately 14.2 Å.

[0038] To evaluate the methane storage performance of the interpenetrating iron-based metal-organic framework material prepared in Example 1, we tested the high-pressure methane adsorption isotherms of the activated interpenetrating iron-based metal-organic framework material at 298 K and 273 K. Figure 10 and 11 As shown, under conditions of 298 K and 65 / 80 bar, the mass-to-adsorption capacity of this material is 0.157 / 0.171 gg. -1 The quality ratio to working capacity is 0.126 / 0.140 gg. -1 The volumetric adsorption capacity at 298 K and 65 / 80 bar was 149 / 163 cm⁻¹. 3 (STP)cm -3 The volumetric working capacity is 119 / 133 cm³. 3 (STP)cm -3 When the temperature decreased to 273 K, both the volumetric adsorption capacity and the mass adsorption capacity increased to some extent. At 273 K and 65 / 80 bar, the mass adsorption capacity was 0.180 / 0.193 g g. -1 The quality ratio to working capacity is 0.134 / 0.147 gg. -1 The volumetric adsorption capacity was 171 / 184 cm⁻¹ at 273 K and 65 / 80 bar. 3 (STP)cm -3 The volumetric working capacity is 126 / 139 cm³. 3 (STP)cm -3 This demonstrates that the intercalated iron-based metal-organic framework material of this invention exhibits excellent performance in methane storage.

[0039] To evaluate the carbon dioxide capture performance of the interpenetrating iron-based metal-organic framework material prepared in Example 1, we tested the adsorption isotherms of the activated interpenetrating iron-based metal-organic framework material for single-component carbon dioxide and nitrogen. Figure 12 and Figure 13 As shown, this material exhibits superior adsorption capacity for carbon dioxide compared to nitrogen under conditions of 0–1 bar, 298 K, and 273 K. At 298 K, the adsorption capacity for carbon dioxide is 24.4 cm⁻¹. 3 g -1 (1.09 mmol g) -1 The adsorption capacity was significantly higher than that of nitrogen (2.3 cm⁻¹). 3 g -1 (0.10 mmol g) -1At 273 K, it also exhibits carbon dioxide (47.0 cm⁻¹). 3 g -1 ) is higher than nitrogen (6.5 cm) 3 g -1 The trend of [missing information] indicates that the material has a stronger affinity for carbon dioxide. Using adsorption data of single-component gases at 298 K and 273 K, the adsorption enthalpies (Q) of carbon dioxide and nitrogen were calculated. st The adsorption enthalpy at zero point best reflects the strength of the affinity between gas molecules and materials. The zero-point adsorption enthalpies for carbon dioxide and nitrogen are 21.3 kJ / mol. -1 and 4.6 kJ mol -1 The results are consistent with those of the single-component adsorption isotherm, indicating that the interaction force between this material and carbon dioxide is indeed stronger than that with nitrogen.

[0040] Separation selectivity is an important indicator for evaluating the separation performance of materials. Based on the adsorption isotherm data of the interpenetrating iron-based metal-organic framework material prepared in Example 1 for single-component carbon dioxide and nitrogen at 298 K (…), Figure 14 The separation selectivity of this material for carbon dioxide and nitrogen was calculated using the ideal adsorption solution theory, such as... Figure 15 As shown, the IAST selectivity for a carbon dioxide / nitrogen volume ratio of 15:85 is 9.20 (1 bar), indicating that the intercalated iron-based metal-organic framework material of the present invention has broad application prospects in flue gas carbon dioxide capture.

Claims

1. An interpenetrating iron-based metal-organic framework material, characterized in that: The molecular formula of the material is [Fe3O(H2O)3(L1)(L2)]. 4 / 3 In the formula, L1 represents deprotonated 4-(4-carboxybenzoamide)benzoic acid, and L2 represents deprotonated 1,3,5-tris(4-carboxyphenyl)benzene; The material belongs to the hexagonal crystal system. R- 3 c Space group, cell parameters are: a = b =34.7425(17) Å, c =92.093(5)Å, α = β =90°, γ =120°, unit cell volume is 96267.4 Å 3 .

2. The interpenetrating iron-based metal-organic framework material according to claim 1, characterized in that: The crystal structure of the material contains two types of cages: one type is an anti-triangular prism cage composed of 9 trinuclear iron clusters, 3 4-(4-carboxybenzoamide)benzoic acid ligands and 5 1,3,5-tris(4-carboxyphenyl)benzene ligands; the other type is a flattened cubic octahedral cage composed of 6 trinuclear iron clusters, 6 4-(4-carboxybenzoamide)benzoic acid ligands and 12 1,3,5-tris(4-carboxyphenyl)benzene ligands.

3. A method for preparing the interpenetrating iron-based metal-organic framework material according to claim 1, characterized in that: After uniformly mixing trinuclear iron clusters, 4-(4-carboxybenzoamide)benzoic acid, 1,3,5-tris(4-carboxyphenyl)benzene, N,N-dimethylformamide, acetic acid and n-pentanol, the mixture was heated at 125-135°C for 24-48 hours under sealed conditions and then cooled to room temperature to obtain an interpenetrating iron-based metal-organic framework material.

4. The method for preparing the interpenetrating iron-based metal-organic framework material according to claim 3, characterized in that: The molar ratio of the trinuclear iron cluster to 4-(4-carboxybenzoamide)benzoic acid and 1,3,5-tris(4-carboxyphenyl)benzene is 1:2-3:1.1-1.

5.

5. The method for preparing the interpenetrating iron-based metal-organic framework material according to claim 3, characterized in that: The molar ratio of the trinuclear iron cluster to acetic acid is 1:80 to 150.

6. The method for preparing the interpenetrating iron-based metal-organic framework material according to claim 3, characterized in that: The volume ratio of N,N-dimethylformamide to n-pentanol is 15–25:

1.

7. A method for activating the interpenetrating iron-based metal-organic framework material according to claim 1, characterized in that: First, use acetone to exchange the solution once every 20-60 minutes for a total of 3-5 times. Then, use n-hexane to exchange the solution once every 20-60 minutes for a total of 3-5 times.

8. The use of the interpenetrating iron-based metal-organic framework material activated by the method of claim 7 in the adsorption and storage of methane.

9. Use of the interpenetrating iron-based metal-organic framework material activated by the method of claim 7 in carbon dioxide capture.

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