Iron-based NCB-type three-element metal organic framework material, preparation method thereof, and application in methane storage

Abstract

The present invention discloses a series of iron-based ncb-type three-element metal organic framework materials and their preparation methods and applications in storing methane. The molecular formula of the materials is [Fe3O(BL P )3(L) 1.5 ], where BL P The invention relates to a series of iron-based NCb-type metal organic framework materials, wherein L represents deprotonated 4-((4-(pyridine-4-yl)phenyl)amide)benzoic acid, L represents deprotonated biphenyldicarboxylic acid, azobenzene-4-4'-dicarboxylic acid, terphenyldicarboxylic acid, bipyridinedicarboxylic acid, or 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid; the material belongs to the cubic crystal system and has an I-43m(217) space group. The series of materials are prepared by a solvent thermal reaction using a trinuclear iron cluster, 4-((4-(pyridine-4-yl)phenyl)amide)benzoic acid, and five different dicarboxylic acids as raw materials, trifluoroacetic acid and acetic acid as templates, and N-methylpyrrolidone as an auxiliary solvent. The series of iron-based NCb-type metal organic framework materials disclosed herein have a large specific surface area and a mesoporous structure, and have broad application prospects in the field of methane storage.

Description

Technical Field

[0001] The invention belongs to the technical field of metal organic framework materials, and in particular relates to five iron-based NCB-type three-element metal organic framework materials. Background Art

[0002] Metal-organic frameworks (MOFs) are a new class of solid porous materials. They are composed of three-dimensional networks formed by the self-assembly of metal ions or metal clusters and organic ligands through coordination bonds. MOFs have a rich and diverse structure and have shown potential applications in energy gas adsorption and storage, carbon capture and conversion, and heterogeneous catalysis. Consequently, they have attracted extensive research attention over the past two decades. To date, tens of thousands of MOFs have been reported, and significant progress has been made in methane storage research.

[0003] UCMC-152 is the MOF material with the highest methane (CH4) volume ratio reported so far (J.Am.Chem.Soc.2010,132,13941-13948.), with a volume ratio working capacity of up to 226cm at 298K and 5-80bar. 3 (STP)cm -3 , but its mass ratio working capacity is 0.271gg -1 The performance is not outstanding. The mass ratio is proportional to the pore volume, but it is more difficult to activate MOF materials with larger pore volume. NU-1501-Al benefits from its large pore volume (2.91cm 3 g -1 ) and specific surface area (7310m 2 g -1 ) is the MOF material with the best mass ratio working capacity at present, but its volume ratio working capacity is not outstanding due to its low skeleton density (Science 2020,368,297-303.). It can be seen that it is very challenging to synthesize MOF materials with both high mass ratio and volume ratio working capacity. Iron-based ncb-type three-element metal organic framework material is an emerging metal organic framework material developed in recent years. Due to its cage-channel hierarchical system and its high connectivity, no open metal sites, suitable cage size and other advantages, it has attracted much attention in the field of clean energy storage. In the previous work, the inventors selected 9-connected ncb topological MOFs as a platform to construct three homonetwork Fe-ncb-MOF materials without open metal sites (ACS Appl. Mater. Interfaces 2021,13,44956-44963.), among which the compound Fe-ncb-ABDC has a mass and volume ratio working capacity of 0.302g at 298K and 5-80bar, respectively. -1and 196cm 3 (STP)cm -3 The results of this study show that as the ligand gradually lengthens, its skeleton density decreases slowly. While ensuring its high volume ratio working capacity, its mass ratio working capacity has the potential to be further increased. Summary of the Invention

[0004] The purpose of the present invention is to provide a series of iron-based NCb-type three-element metal organic framework materials, and to provide a preparation method, an activation method and an application for the series of materials.

[0005] For the above purpose, the present invention provides an iron-based ncb-type three-element metal organic framework material with the molecular formula of [Fe3O(BL P )3(L) 1.5 ], where BL P represents deprotonated 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, and L represents any one of deprotonated biphenyldicarboxylic acid (BPDC), deprotonated azobenzene-4-4'-dicarboxylic acid (ABDC), deprotonated terphenyldicarboxylic acid (TPDC), deprotonated bipyridinedicarboxylic acid (BPyDC), and deprotonated 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid (BTDDC).

[0006] The iron-based ncb-type three-element metal organic framework materials provided by the present invention all belong to the cubic system and the I-43m (217) space group. When L represents BPDC, it is recorded as compound 1, and the molecular formula is [Fe3O(BL P )3(BPDC) 1.5 ], the unit cell parameters are: α=β=γ=90°, the unit cell volume is When L represents ABDC, it is recorded as compound 2, and the molecular formula is [Fe3O(BL P )3(ABDC) 1.5 ], the unit cell parameters are: α=β=γ=90°, the unit cell volume is When L represents TPDC, it is recorded as compound 3, and the molecular formula is [Fe3O(BL P )3(TPDC) 1.5 ], the unit cell parameters are: α=β=γ=90°, the unit cell volume is When L represents BPyDC, it is recorded as compound 4, and the molecular formula is [Fe3O(BL P )3(BPyDC) 1.5], the unit cell parameters are the same as those of compound 1; when L represents BTDDC, it is recorded as compound 5, and the molecular formula is [Fe3O(BL P )3(BTDDC) 1.5 ], and the unit cell parameters are the same as those of compound 3.

[0007] The structure of the iron-based NCB-type three-element metal-organic framework material of the present invention contains three cages of different sizes: cage I is a distorted cubic cage composed of eight trinuclear iron clusters, 12 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid, and two dicarboxylic acid ligands; cage II is a trigonal pyramidal cage composed of four trinuclear iron clusters, three 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid, and three dicarboxylic acid ligands; and cage III is a tetrahedral cage composed of four trinuclear iron clusters and six dicarboxylic acid ligands. The number ratio of cages I, II, and III is 3:1:4, and each cage I is interconnected to form one-dimensional channels along three directions, forming a hierarchical channel-cage double pore system within the overall structure.

[0008] The preparation method of the above-mentioned iron-based ncb-type three-element metal organic framework material is as follows: trinuclear iron cluster (Fe3O(CH3COO)6(H2O)3), 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid (HBL P ), N,N-dimethylformamide, trifluoroacetic acid, acetic acid, N-methylpyrrolidone, and dicarboxylic acid are uniformly mixed, heated at 110-125° C. under closed conditions for reaction for 24-48 hours, and cooled to room temperature to obtain an iron-based ncb-type three-element metal-organic framework material. The dicarboxylic acid is selected from any one of biphenyldicarboxylic acid (H2BPDC), azobenzene-4-4'-dicarboxylic acid (H2ABDC), terphenyldicarboxylic acid (H2TPDC), bipyridinedicarboxylic acid (H2BPyDC), and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) (H2BTDDC).

[0009] In the above preparation method, it is preferred that the molar ratio of the trinuclear iron cluster to biphenyl dicarboxylic acid, bipyridine dicarboxylic acid, azobenzene-4-4'-dicarboxylic acid, terphenyl dicarboxylic acid, 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) is 1:1, and the molar ratio of the trinuclear iron cluster to biphenyl dicarboxylic acid or bipyridine dicarboxylic acid is 1:1. The molar ratio of the 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid to azobenzene-4-4'-dicarboxylic acid is 4:1, the molar ratio of the 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid to terphenyldicarboxylic acid or 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) is 6:1.

[0010] In the above preparation method, the molar ratio of the trinuclear iron cluster to acetic acid is preferably 1:0.1 to 0.15.

[0011] In the above preparation method, the volume ratio of N,N-dimethylformamide, trifluoroacetic acid, acetic acid and N-methylpyrrolidone is preferably 6-7:0.01-0.05:0.1:0.1-0.2.

[0012] The activation method of the above-mentioned iron-based ncb-type three-element metal organic framework material is as follows: compound 1 is first exchanged once with dichloromethane every 8 hours for a total of 3 times, then exchanged once with acetonitrile every 8 hours for a total of 3 times, then exchanged once with n-hexane every 8 hours for a total of 3 times, and then exchanged once with supercritical carbon dioxide every half an hour for a total of 3 times; compound 2 is first exchanged once with dichloromethane every 8 hours for a total of 6 times, then exchanged once with acetonitrile every 8 hours for a total of 6 times, then exchanged once with n-hexane every 8 hours for a total of 6 times, and finally exchanged once with supercritical carbon dioxide every half an hour for a total of 3 times; compound 3 is first exchanged once with N-methylpyrrolidone at 85°C every 8 hours for a total of 3 times, and then The reaction mixture was exchanged with ethanol once every 6 hours for a total of 2 exchanges, then with dichloromethane once every 8 hours for a total of 3 exchanges, then with acetonitrile once every 8 hours for a total of 3 exchanges, then with n-hexane once every 8 hours for a total of 6 exchanges, and finally with supercritical carbon dioxide once every half an hour for a total of 3 exchanges; the activation method of compound 4 was the same as that of compound 1; compound 5 was first exchanged with N-methylpyrrolidone at 85°C once every 8 hours for a total of 3 exchanges, then with dichloromethane once every 8 hours for a total of 3 exchanges, then with acetonitrile once every 8 hours for a total of 3 exchanges, then with n-hexane once every 8 hours for a total of 6 exchanges, and finally with supercritical carbon dioxide once every half an hour for a total of 3 exchanges.

[0013] The iron-based NCb-type three-element metal organic framework material activated by the above method has a large specific surface area and pore volume, and can be used for adsorption and storage of methane.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. The present invention uses trinuclear iron clusters as metal sources, 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid and five different dicarboxylic acids as organic ligands, trifluoroacetic acid and acetic acid as templates, and prepares a series of iron-based NCB-type three-element metal-organic framework materials through solvent thermal reaction. By activating the series of iron-based NCB-type three-element metal-organic framework materials, the nitrogen adsorption isotherms of the activated series of materials at 77K were tested. The results show that the series of materials have large specific surface areas and pore volumes, with compound 1 to compound 5 being 4881m 2 g-1 、4954m 2 g -1 、5106m 2 g -1 、4824m 2 g -1 、4938m 2 g -1 , and the pore volumes are 1.93 cm 3 g -1 , 2.13cm 3 g -1 、2.44cm 3 g -1 、1.90cm 3 g -1 、2.19cm 3 g -1 This series of iron-based ncb-type three-element metal-organic framework materials has broad application prospects in the field of methane gas adsorption and storage.

[0016] 2. The high-pressure methane storage performance test of the series of iron-based ncb-type three-element metal organic framework materials of the present invention shows that this series of materials has excellent performance in terms of mass ratio due to its large pore volume and specific surface area. The mass ratio is improved compared with the Fe-ncb-ABDC series and is second only to NU-1501 under the same conditions. At the same time, it also has a high volume ratio, especially under the conditions of 273K and 5-80bar, with the volume ratio and mass ratio being 0.533g / cm2 respectively. -1 、232cm 3 (STP)cm -3 , and performs well in natural gas adsorption applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a series of iron-based NCB-type metal organic framework materials of the present invention.

[0018] Figure 2 It is a topological schematic diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0019] Figure 3 It is a cage schematic diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0020] Figure 4 It is a window schematic diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0021] Figure 5 It is the powder X-ray diffraction pattern of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0022] Figure 6 This is a thermal analysis diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0023] Figure 7 This is a gas adsorption isotherm diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0024] Figure 8 This is the pore size distribution diagram of the series of iron-based NCB-type metal organic framework materials of the present invention.

[0025] Figure 9 This is the methane adsorption isotherm of the series of iron-based NCB-type metal organic framework materials of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the protection scope of the present invention is not limited to these examples.

[0027] Example 1

[0028] 10 mg (0.017 mmol) of trinuclear iron cluster (Fe3O(CH3COO)6(H2O)3)), 19.08 mg (0.06 mmol) of 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, 3.63 mg (0.015 mmol) of biphenyldicarboxylic acid, 6 mL of N,N-dimethylformamide, 0.15 mL of N-methylpyrrolidone, 0.1 mL (0.00175 mmol) of acetic acid, and 0.01 mL of trifluoroacetic acid were mixed and added to a 20 mL scintillation vial, sealed, and placed in a 120°C oven to react for 24 hours. The resulting dark brown polyhedral block crystals were compound 1. The activation method of compound 1 is as follows: first, exchange with dichloromethane once every 8 hours for a total of 3 exchanges, then exchange with acetonitrile once every 8 hours for a total of 3 exchanges, then exchange with n-hexane once every 8 hours for a total of 3 exchanges, and finally exchange with supercritical carbon dioxide once every half an hour for a total of 3 exchanges. After the exchange, keep at 40°C for 1 hour, start to reduce the pressure, and the pressure reduction time lasts for 6 to 8 hours.

[0029] Example 2

[0030] Mix 10 mg (0.017 mmol) of trinuclear iron cluster (Fe₃O(CH₃COO)₆(H₂O)₃), 23.8 mg (0.075 mmol) of 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, 4.05 mg (0.015 mmol) of azobenzene-4-4'-dicarboxylic acid, 6 mL of N,N-dimethylformamide, 0.18 mL of N-methylpyrrolidone, 0.1 mL (0.00175 mmol) of acetic acid, and 0.01 mL of trifluoroacetic acid. The mixture was then added to a 20 mL scintillation vial, sealed, and placed in a 120°C oven to react for 24 hours. The resulting dark brown polyhedral block crystals were compound 2. The activation method of compound 2 is as follows: first, exchange with dichloromethane once every 8 hours for a total of 6 exchanges, then exchange with acetonitrile once every 8 hours for a total of 6 exchanges, then exchange with n-hexane once every 8 hours for a total of 6 exchanges, and finally exchange with supercritical carbon dioxide once every half an hour for a total of 3 exchanges. After the exchanges, keep at 40°C for 1 hour, start to reduce the pressure, and the pressure reduction time lasts for 6 to 8 hours.

[0031] Example 3

[0032] 10 mg (0.017 mmol) of trinuclear iron cluster (Fe₃O(CH₃COO)₆(H₂O)₃), 23.8 mg (0.075 mmol) of 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, 4.77 mg (0.015 mmol) of terphenyldicarboxylic acid, 7 mL of N,N-dimethylformamide, 0.1 mL of N-methylpyrrolidone, 0.1 mL (0.00175 mmol) of acetic acid, and 0.02 mL of trifluoroacetic acid were mixed and added to a 20 mL scintillation vial, sealed, and placed in a 120°C oven to react for 48 hours. The resulting dark brown polyhedral block crystals were compound 3. The activation method of compound 3 is as follows: first, exchange with N-methylpyrrolidone at 85°C once every 8 hours for a total of 3 exchanges, then exchange with ethanol once every 6 hours for a total of 2 exchanges, then exchange with dichloromethane once every 8 hours for a total of 3 exchanges, then exchange with acetonitrile once every 8 hours for a total of 3 exchanges, then exchange with n-hexane once every 8 hours for a total of 6 exchanges, and finally exchange with supercritical carbon dioxide once every half an hour for a total of 3 exchanges. After the exchanges, keep at 40°C for 1 hour, start to reduce the pressure, and the pressure reduction time lasts for 6 to 8 hours.

[0033] Example 4

[0034] 10 mg (0.017 mmol) of trinuclear iron cluster (Fe3O(CH3COO)6(H2O)3)), 19.08 mg (0.06 mmol) of 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, 2.44 mg (0.010 mmol) of bipyridinedicarboxylic acid, 6 mL of N,N-dimethylformamide, 0.15 mL of N-methylpyrrolidone, 0.1 mL (0.00175 mmol) of acetic acid, and 0.01 mL of trifluoroacetic acid were mixed and added to a 20 mL scintillation vial, sealed, and placed in a 120°C oven to react for 24 hours. The resulting dark brown polyhedral block crystals were compound 4. The activation method of compound 4 is as follows: first, exchange with dichloromethane once every 8 hours for a total of 3 exchanges, then exchange with acetonitrile once every 8 hours for a total of 3 exchanges, then exchange with n-hexane once every 8 hours for a total of 3 exchanges, and then exchange with supercritical carbon dioxide once every half an hour for a total of 3 exchanges. After the exchange, keep at 40°C for 1 hour, start to reduce the pressure, and the pressure reduction time lasts for 6 to 8 hours.

[0035] Example 5

[0036] 10 mg (0.017 mmol) of trinuclear iron cluster (Fe₃O(CH₃COO)₆(H₂O)₃), 28.6 mg (0.09 mmol) of 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, 2.44 mg (0.015 mmol) of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid, 7 mL of N,N-dimethylformamide, 0.15 mL of N-methylpyrrolidone, 0.1 mL (0.00175 mmol) of acetic acid, and 0.05 mL of trifluoroacetic acid were mixed and added to a 20 mL scintillation vial, sealed, and placed in a 120°C oven to react for 48 hours. The resulting dark brown polyhedral block crystals were compound 5. The activation method of compound 5 is as follows: first, exchange with N-methylpyrrolidone at 85°C once every 8 hours for a total of 3 exchanges, then exchange with dichloromethane once every 8 hours for a total of 3 exchanges, then exchange with acetonitrile once every 8 hours for a total of 3 exchanges, then exchange with n-hexane once every 8 hours for a total of 6 exchanges, and finally exchange with supercritical carbon dioxide once every half an hour for a total of 3 exchanges. After the exchanges, keep at 40°C for 1 hour, start to reduce the pressure, and the pressure reduction time lasts for 6 to 8 hours.

[0037] The structures of the above compounds 1 to 5 were characterized by single crystal X-ray diffraction, and the molecular formulas were compound 1: [Fe3O(BL P )3(BPDC) 1.5 ], Compound 2: [Fe3O(BL P )3(ABDC) 1.5 ], Compound 3: [Fe3O(BLP )3(TPDC) 1.5 ], Compound 4: [Fe3O(BL P )3(BPyDC) 1.5 ], Compound 5: [Fe3O(BL P )3(BTDDC) 1.5 ], all belong to the cubic system, I-43m (217) space group, and the unit cell parameters are: Compound 1 and Compound 4: α=β=γ=90°, compound 2: α=β=γ=90°, compound 3 and compound 5: α=β=γ=90°, and the unit cell volumes are compound 1 and compound 4 respectively: Compound 2: Compound 3 and Compound 5: In the crystal structure, the molecular building block of the inorganic part is a trinuclear iron cluster [Fe3O(O2C-)6(NC5-)3]. Each [Fe3O(O2C-)6(NC5-)3] oxygen-centered trinuclear iron cluster is in a 9-connected state, and the ligands connected to it include three deprotonated dicarboxylic acids and six deprotonated 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid. The three are interconnected to form a three-dimensional periodic network structure. Using the node method, the oxygen-centered trinuclear iron cluster is simplified to a 9-connected node, and the 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and dicarboxylic acid are simplified to two 2-connected rods respectively. Topological analysis shows that the structure is an ncb topology, see Figure 1 、 2 . This series of structures has three cages with a ratio of 3:1:4, and their shapes and sizes are different. Cage I is a distorted cubic cage composed of 8 trinuclear iron clusters, 12 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and 2 dicarboxylic acid ligands; cage II is a trigonal pyramidal cage composed of 4 trinuclear iron clusters, 3 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and 3 dicarboxylic acid ligands; cage III is a tetrahedral cage composed of 4 trinuclear iron clusters and 6 dicarboxylic acid ligands. In addition, each cage I is interconnected to form a one-dimensional channel along three directions, thereby forming a hierarchical channel-cage double-pore system within the overall structure. The cage size is as follows. Figure 3As shown. At the same time, there are three types of windows in this structure. Window I is an equilateral triangle window composed of 3 trinuclear iron clusters and 3 dicarboxylic acid ligands; Window II is an isosceles triangle window composed of 3 trinuclear iron clusters, 2 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and 1 dicarboxylic acid ligand; Window III is a distorted quadrilateral window composed of 4 trinuclear iron clusters and 4 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid. Its size is shown in Figure 4 .

[0038] Figure 5 The results show that the positions of the diffraction peaks in the powder X-ray diffraction patterns of the activated compounds 1, 2, and 5 are completely consistent with the positions of the diffraction peaks in the powder X-ray diffraction patterns simulated using the structural data obtained from single crystal structure analysis. This indicates that the single crystal structure determined by X-ray diffractometer can well describe the material structure. It also shows that the present invention can produce a large number of pure phase series of iron-based NCb-type three-element metal-organic framework materials. The compound structure remains intact after exchange with dichloromethane and n-hexane, and is pure phase. Because compounds 1 and 4, and compounds 3 and 5 have the same network structure, to ensure the purity of the subsequent test samples, the simulated peaks of the structural data obtained from the single crystal structure analysis of compound 4 and compound 1 were compared, and the simulated peaks of compound 3 and compound 5 were compared. The results show that all are pure phases.

[0039] pass Figure 6 From the thermogravimetric analysis curves, it can be seen that the skeletons of compounds 1, 2 and 5 completely collapsed after 420°C, and the skeletons of compounds 3 and 4 completely collapsed after 620°C, indicating that they have good thermal stability.

[0040] In order to confirm the porosity of the above-obtained series of iron-based ncb-type tri-element metal organic framework materials, the N2 adsorption isotherm test of the activated compounds 1 to 5 in the examples was carried out at 77K, and a typical "IV" type curve was obtained (see Figure 7 ), proving that it is a mesoporous material. The N2 adsorption capacity of compounds 1 to 5 reaches 1245 cm 3 g -1 、1377cm 3 g -1 、1576cm 3 g -1 、1223cm 3 g -1 、1417cm 3 g -1 , and the BET specific surface areas are 4881m 2 g -1 、4954m 2 g -1 、5106m2 g -1 、4824m 2 g -1 、4938m 2 g -1 , and the pore volumes are 1.93 cm 3 g -1 , 2.13cm 3 g -1 、2.44cm 3 g -1 、1.90cm 3 g -1 、2.19cm 3 g -1 .from Figure 8 It can be seen that there are three types of pores in the sample.

[0041] In order to evaluate the methane storage performance of compounds 1-5, we tested the high-pressure methane adsorption isotherms of activated compounds 1-5 at 298K and 273K (see Figure 9 The mass ratio adsorption of compounds 1 to 5 showed a positive correlation with the pore volume, which was 0.344 / 0.377 g·g at 298 K and 65 / 80 bar, respectively. -1 、0.367 / 0.415gg -1 、0.385 / 0.441gg -1 、0.329 / 0.380gg -1 、0.371 / 0.418gg -1 , mass ratio working capacity is 0.300 / 0.333gg respectively -1 、0.325 / 0.373gg -1 、0.341 / 0.397gg -1 、0.290 / 0.341gg -1 、0.323 / 0.370gg -1 The volume ratio adsorption of compounds 1 to 5 at 298K and 65 / 80bar is 170 / 188cm 3 (STP)cm -3 、174 / 196cm 3 (STP)cm -3 、169 / 193cm 3 (STP)cm -3 、167 / 192cm 3 (STP)cm -3 、176 / 197cm 3 (STP)cm -3The volume ratio working capacity is 148 / 166cm 3 (STP)cm -3 、155 / 177cm 3 (STP)cm -3 、150 / 174cm 3 (STP)cm -3 、147 / 172cm 3 (STP)cm -3 、154 / 175cm 3 (STP)cm -3 When the temperature is lowered to 273K, the volume ratio adsorption capacity and mass ratio adsorption capacity increase significantly. At 273K and 65 / 80bar, the mass ratio adsorption capacity is 0.401 / 0.447g respectively. -1 、0.447 / 0.508gg -1 、0.526 / 0.598gg -1 、0.390 / 0.432gg -1 、0.476 / 0.527gg -1 , the mass ratio working capacity is 0.341 / 0.387gg respectively -1 、0.388 / 0.449gg -1 、0.461 / 0.533gg -1 、0.336 / 0.378gg -1 、0.409 / 0.460gg -1 At 273K and 65 / 80bar, the volume ratio adsorption capacity is 200 / 224cm 3 (STP)cm -3 、212 / 240cm 3 (STP)cm -3 , 230 / 260cm 3 (STP)cm -3 、195 / 215cm 3 (STP)cm -3 、225 / 248cm 3 (STP)cm -3 The volume ratio working capacity is 170 / 194cm 3 (STP)cm -3 、185 / 213cm 3 (STP)cm -3 、202 / 232cm 3 (STP)cm -3 、168 / 188cm 3 (STP)cm -3、193 / 216cm 3 (STP)cm -3 This indicates that compounds 1 to 5 of the present invention have excellent performance in methane storage.

Claims

1. An iron-based ncb-type three-element metal-organic framework material, characterized by: The molecular formula of the material is [Fe3O(BL P )3(L) 1.5 ], where BL P represents deprotonated 4-((4-(pyridin-4-yl)phenyl)amido)benzoic acid, L represents any one of deprotonated biphenyldicarboxylic acid, deprotonated azobenzene-4-4'-dicarboxylic acid, deprotonated terphenyldicarboxylic acid, deprotonated bipyridinedicarboxylic acid, and deprotonated 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid; The material belongs to the cubic system, I-43m (217) space group, wherein when L represents deprotonated biphenyldicarboxylic acid or deprotonated bipyridinedicarboxylic acid, the unit cell parameters are: α=β=γ=90°, the unit cell volume is When L represents deprotonated azobenzene-4-4'-dicarboxylic acid, the unit cell parameters are: α=β=γ=90°, the unit cell volume is When L represents deprotonated terphenyldicarboxylic acid or deprotonated 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid, the unit cell parameters are: α=β=γ=90°, the unit cell volume is 2. The iron-based NCB-type three-element metal-organic framework material according to claim 1, characterized in that: There are three cages of different sizes in the structure. Cage I is a distorted cubic cage composed of eight trinuclear iron clusters, 12 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and two dicarboxylic acid ligands; cage II is a trigonal pyramidal cage composed of four trinuclear iron clusters, three 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid and three dicarboxylic acid ligands; cage III is a tetrahedral cage composed of four trinuclear iron clusters and six dicarboxylic acid ligands; the number ratio of cages I, II and III is 3:1:

4. Each cage I is interconnected to form a one-dimensional channel along three directions, forming a hierarchical channel-cage double pore system within the overall structure.

3. A method for preparing the iron-based NCB-type three-element metal-organic framework material according to claim 1, characterized in that: After the trinuclear iron cluster, 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid, N,N-dimethylformamide, trifluoroacetic acid, acetic acid, N-methylpyrrolidone, and dicarboxylic acid are evenly mixed, the mixture is heated at 110-125° C. for 24-48 hours under closed conditions, and the mixture is cooled to room temperature to obtain an iron-based NCB-type three-element metal-organic framework material; wherein the dicarboxylic acid is selected from any one of biphenyldicarboxylic acid, azobenzene-4-4'-dicarboxylic acid, terphenyldicarboxylic acid, bipyridinedicarboxylic acid, and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid).

4. The method for preparing the iron-based NCB-type three-element metal-organic framework material according to claim 3, characterized in that: The molar ratio of the trinuclear iron cluster to biphenyldicarboxylic acid, bipyridinedicarboxylic acid, azobenzene-4-4'-dicarboxylic acid, terphenyldicarboxylic acid, and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) is 1:1, the molar ratio of the 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid to biphenyldicarboxylic acid or bipyridinedicarboxylic acid is 4:1, the molar ratio of the 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid to azobenzene-4-4'-dicarboxylic acid is 5:1, and the molar ratio of the 4-((4-(pyridin-4-yl)phenyl)amide)benzoic acid to terphenyldicarboxylic acid or 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) is 6:

1.

5. The method for preparing the iron-based NCB-type three-element metal-organic framework material according to claim 3, characterized in that: The molar ratio of the trinuclear iron cluster to acetic acid is 1:0.1-0.15, and the volume ratio of the N,N-dimethylformamide, trifluoroacetic acid, acetic acid, and N-methylpyrrolidone is 6-7:0.01-0.05:0.1:0.1-0.

2.

6. A method for activating the iron-based NCB-type three-element metal-organic framework material according to claim 1, characterized in that: When L represents deprotonated biphenyldicarboxylic acid or deprotonated bipyridinedicarboxylic acid, the material is first exchanged with dichloromethane once every 8 hours for a total of 3 exchanges, then exchanged with acetonitrile once every 8 hours for a total of 3 exchanges, then exchanged with n-hexane once every 8 hours for a total of 3 exchanges, and then exchanged with supercritical carbon dioxide once every half an hour for a total of 3 exchanges; When L represents deprotonated azobenzene-4-4'-dicarboxylic acid, the material is first exchanged with dichloromethane once every 8 hours for a total of 6 times, then exchanged with acetonitrile once every 8 hours for a total of 6 times, then exchanged with n-hexane once every 8 hours for a total of 6 times, and finally exchanged with supercritical carbon dioxide once every half an hour for a total of 3 exchanges; When L represents deprotonated terphenyldicarboxylic acid, the material is first exchanged with N-methylpyrrolidone at 85° C. once every 8 hours for a total of 3 exchanges, then exchanged with ethanol once every 6 hours for a total of 2 exchanges, then exchanged with dichloromethane once every 8 hours for a total of 3 exchanges, then exchanged with acetonitrile once every 8 hours for a total of 3 exchanges, then exchanged with n-hexane once every 8 hours for a total of 6 exchanges, and finally exchanged with supercritical carbon dioxide once every half an hour for a total of 3 exchanges; When L represents deprotonated 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid, the material is first exchanged with N-methylpyrrolidone at 85°C once every 8 hours for a total of 3 exchanges, then exchanged with dichloromethane once every 8 hours for a total of 3 exchanges, then exchanged with acetonitrile once every 8 hours for a total of 3 exchanges, then exchanged with n-hexane once every 8 hours for a total of 6 exchanges, and finally exchanged with supercritical carbon dioxide once every half an hour for a total of 3 exchanges.

7. Use of the iron-based NCB-type three-element metal organic framework material activated by the method according to claim 6 in the adsorption and storage of methane.

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