Pyrenyl metal organic framework material suitable for low-temperature methane adsorption storage as well as preparation and application of pyrenyl metal organic framework material

Abstract

The invention discloses a pyrenyl metal organic framework material Cr-TBPP-MOF suitable for low-temperature methane adsorption and storage as well as a preparation method and application of the pyrenyl metal organic framework material Cr-TBPP-MOF in low-temperature methane adsorption. The preparation method comprises the following steps: firstly, synthesizing an eight-connection pyrenyl ligand H8TBPP from 1, 3, 6, 8-tetrabromo pyrene serving as a raw material under a specific and appropriate condition, and then preparing the high-porosity metal organic framework material Cr-TBPP-MOF from the eight-connection pyrenyl ligand H8TBPP and a Cr3 metal cluster under a specific and appropriate condition. The synthesis and preparation method is easy to operate, low in cost and suitable for efficient low-temperature methane adsorption and storage.

Description

Technical Field

[0001] The present invention relates to the field of metal organic framework materials, and in particular to a pyrene-based metal organic framework material suitable for low-temperature methane adsorption storage, and a preparation method and application thereof. Background Art

[0002] The burning of fossil fuels produces a large amount of carbon dioxide, causing various environmental problems such as the greenhouse effect. Therefore, transitioning from traditional energy to clean and renewable energy alternatives is a viable way to achieve sustainable development.

[0003] Methane, the main component of natural gas, emits less carbon dioxide when burned and uses heat more efficiently than other fossil fuels, making it a promising candidate for transportation and other applications.

[0004] Liquefied natural gas (LNG) is currently considered one of the most effective natural gas storage technologies. However, the low temperature characteristics of LNG storage tanks will inevitably produce boil-off gas (BOG), which will increase tank pressure and cause safety hazards. Therefore, the recovery and storage of BOG is crucial to ensure transportation safety and reduce economic losses.

[0005] Adsorbed natural gas (ANG) is an emerging technology driven by state-of-the-art porous materials. Recently, the coupling of LNG regasification and ANG buffering processes, referred to as the LNG-ANG coupled system, is considered to enable efficient recovery of BOG in a safer and more economical manner. In this approach, the adsorbent is incorporated into the ANG tank to achieve high methane adsorption capacity. Despite the high demand for porous adsorbents with excellent low-temperature methane capacity, research and development in this area remains underexplored.

[0006] Metal-organic frameworks (MOFs) are porous framework materials composed of metal ions or clusters and organic ligands. MOFs have the characteristics of high porosity, high specific surface area and easily controllable pore structure, and have attracted more and more attention from researchers as gas adsorbents.

[0007] Metal-organic frameworks (MOFs) are composed of inorganic metal nodes and organic ligands and are crystalline porous materials with tunable pore sizes and ultrahigh surface areas. MOFs have been widely studied for their environmental and energy-related applications, including gas adsorption and separation, water adsorption, and catalysis. High-porosity MOFs offer great potential for methane storage, especially at cryogenic conditions.

[0008] The patent specification with the announcement number CN112625069B discloses a cobalt metal organic framework material based on pyrene tetrapyrazole ligand, a preparation method and its application, which belongs to the technical field of crystalline materials. The chemical formula is Co(H 4 TPP)(CH 3COO 2 (H 2 O)(CH 3 CN) 2 , H 4 TPP is an organic ligand 1,3,6,8-tetrakis(1H-pyrazol-4-yl)pyrene. The synthesis method of the metal-organic framework is that the organic ligand 1,3,6,8-tetrakis(1H-pyrazol-4-yl)pyrene and cobalt nitrate are reacted in a mixed solution of N,N-dimethylformamide, acetic acid and acetonitrile under closed conditions to obtain crystals through solvothermal reaction; this metal-organic framework material shows potential application in selective adsorption and separation of carbon dioxide, methane and nitrogen. Summary of the invention

[0009] The present invention provides a pyrene-based metal organic framework material (Cr-TBPP-MOF) suitable for low-temperature methane adsorption and storage, a preparation method thereof, and an application in low-temperature methane adsorption. This metal organic framework material has a novel structure and excellent properties, and the pore volume can reach 1.31cm 3 g -1 , and can have 3700m 2 g -1 High specific surface area and excellent low temperature methane working capacity.

[0010] The specific technical solutions are as follows:

[0011] [1] A pyrene-based metal organic framework material suitable for low-temperature methane adsorption storage, composed of organic ligand H 8 TBPP and Cr 3 Metal clusters (Cr 3 cluster) replaces the coordination connection to form, and its formation process can be seen in Figure 1 (M in the figure represents Cr).

[0012] The organic ligand H 8 TBPP has the chemical structure shown below:

[0013]

[0014] The Cr 3 Metal clusters have the following chemical structure:

[0015]

[0016] In the process of substitution coordination, the organic ligand H 8 TBPP firstly uses its carboxyl group to 3 The same structural substitution of OCO in metal clusters is similar to that of Fe 3 The metal clusters form coordination bonds, and then Fe3 The Fe atoms in the metal cluster are exchanged for Cr atoms to form Cr 3 Pyrene-based metal-organic frameworks connected by metal clusters and organic ligands.

[0017] The Fe 3 Metal clusters have the following chemical structure:

[0018]

[0019] The single crystal structure data of the pyrene-based metal organic framework material are as follows:

[0020]

[0021] [2] The method for preparing the pyrene-based metal organic framework material according to [1] comprises the steps of:

[0022] S1, the organic ligand H 8 TBPP and basic ferric acetate were added to a mixed solution of N,N-dimethylformamide (DMF) and acetic acid (HAc) for solvothermal reaction to obtain metal organic framework material 2;

[0023] S2, adding the metal organic framework material 2 to a chromium chloride N,N-dimethylformamide solution to carry out a metal exchange reaction to obtain the pyrene-based metal organic framework material.

[0024] The present invention firstly designs and synthesizes a novel octa-connected pyrene-based ligand, and then synthesizes the high-porosity metal-organic framework material Cr-TBPP-MOF under specific and appropriate conditions. In the LNG-ANG coupling system, Cr-TBPP-MOF has excellent low-temperature methane working capacity and can be used multiple times in cycles.

[0025] The organic ligand H 8 The method for preparing TBPP may include the steps of:

[0026] (1) Under nitrogen protection, 1,3,5-tribromobenzene, (4-(methoxycarbonyl)phenyl)boric acid, Na 2 CO 3 , [Pd(PPh 3 ) 4 ](tetrakis(triphenylphosphine)palladium) was added to a degassed mixed solvent of toluene / methanol / water, the solution was stirred and refluxed, the reaction product was extracted with dichloromethane and washed with brine, anhydrous MgSO 4 After drying, filtering and drying the organic solvent, the residue was separated by column chromatography, the eluent was a mixture of dichloromethane and petroleum ether, and the eluent was dried to obtain a white solid 1 having the following chemical structure:

[0027]

[0028] (2) Under anhydrous and oxygen-free conditions, white solid 1, bis(pinacol)diboron, KOAc, PdCl 2 (dppf)(1,1'-bis(diphenylphosphinodiphenylferrocenepalladium dichloride) was added to dioxane, and the reaction mixture was heated at 85-95°C (preferably 90°C) under nitrogen. After the reaction was completed, the mixture was extracted with chloroform and washed with brine. The combined organic extracts were washed with anhydrous MgSO 4 After drying, filtering and drying the organic solvent, the crude product was purified by flash column using dichloromethane / petroleum ether as eluent to obtain a white solid 2 having the following chemical structure:

[0029]

[0030] (3) Under nitrogen protection, dioxane and K were added to 1,3,6,8-tetrabromopyrene, white solid 2 and Pd SPhos Gen III (CAS: 1445085-82-4). 3 PO 4 The aqueous solution is stirred at 85-95° C. (preferably 90° C.) under a nitrogen atmosphere to react. After the reaction is completed, the reaction solution is filtered and washed with water. The obtained dark green filtrate is fully dissolved in chloroform, filtered through diatomaceous earth and the chloroform is removed under reduced pressure. The collected yellow-green product is hydrolyzed with NaOH, refluxed overnight with tetrahydrofuran (THF) / ethanol (EtOH) / water as a solvent, and the organic solvent is removed by rotation. HCl is added to a pH of 1.5-2.5 (preferably 2), filtered, the filter cake is washed with water, and vacuum dried to obtain the organic ligand H 8 TBPP.

[0031] In step (1), the molar ratio of 1,3,5-tribromobenzene to (4-(methoxycarbonyl)phenyl)boric acid may be 1:2 to 3, preferably 1:2.5.

[0032] In step (1), Na 2 CO 3 The molar ratio of 1,3,5-tribromobenzene can be 4 to 6:1, preferably 5:1.

[0033] In step (1), [Pd(PPh 3 ) 4 ] can be added at 3% to 6% of the molar amount of 1,3,5-tribromobenzene.

[0034] In step (1), the ratio of the mixed solvent of toluene / methanol / water to 1,3,5-tribromobenzene can be 8-12 mL:1 mmol, preferably 10 mL:1 mmol.

[0035] In step (1), the volume ratio of toluene, methanol and water in the mixed solvent of toluene / methanol / water can be 2:1:1.

[0036] In step (1), Na 2 CO 3 It can be added in the form of a solution, wherein the solvent can be water, Na 2 CO 3 The solution concentration may be 1.5 to 2.5 M, preferably 2 M.

[0037] In step (1), the stirring reflux temperature can be 75-85°C, preferably 80°C.

[0038] In step (1), the stirring reflux time can be 48 to 52 hours, preferably 50 hours.

[0039] In step (1), the volume ratio of dichloromethane to petroleum ether in the eluent used for column chromatography can be 1:4.

[0040] In step (2), the molar ratio of the white solid 1 to bis(pinacol)diboron can be 1:1 to 1.2, preferably 1:1.1.

[0041] In step (2), the molar ratio of KOAc to the white solid 1 can be 7 to 8:1.

[0042] In step (2), PdCl 2 (dppf) can be added at 3% to 6% of 1 mol of white solid.

[0043] In step (2), the usage ratio of dioxane to white solid 1 can be 20-22 mL:1 mmol.

[0044] In step (2), the heating time at 75 to 85° C. (preferably 80° C.) can be 10 to 14 hours.

[0045] In step (2), the volume ratio of dichloromethane to petroleum ether in the eluent dichloromethane / petroleum ether used in the column chromatography can be 3:1.

[0046] In step (3), the molar ratio of 1,3,6,8-tetrabromopyrene to the white solid 2 can be 1:4 to 6, preferably 1:5.

[0047] In step (3), Pd SPhos Gen III may be added at 14% to 16% of the molar amount of 1,3,6,8-tetrabromopyrene, preferably 15%.

[0048] In step (3), dioxane and K 3 PO 4The ratio of the total volume of the aqueous solution to the molar amount of 1,3,6,8-tetrabromopyrene may be 95-105 mL:1 mmol, preferably 100 mL:1 mmol.

[0049] In step (3), dioxane and K 3 PO 4 The volume ratio of the aqueous solution may be 3 to 5:1, preferably 4:1.

[0050] In step (3), K 3 PO 4 K in aqueous solution 3 PO 4 The concentration may be 0.9 to 1.1 M, preferably 1 M.

[0051] In step (3), the stirring reaction time can be 1.5 to 2.5 days, preferably 2 days.

[0052] In step (3), in the hydrolysis step, the volume ratio of tetrahydrofuran, ethanol and water in the solvent tetrahydrofuran / ethanol / water can be 5:5:1.

[0053] In step (3), NaOH can be added in the form of a solution, wherein the solvent is water and the concentration is 5 to 7 M, preferably 6 M.

[0054] In step (3), the temperature of the overnight reflux can be controlled at 115-125°C, preferably 120°C.

[0055] In some embodiments, in step S1, the basic ferric acetate and the organic ligand H 8 The mass ratio of TBPP is not less than 2:1.

[0056] In step S1, the volume ratio of N,N-dimethylformamide to acetic acid in the mixed solution of N,N-dimethylformamide and acetic acid can be 1.5-2.5:1, preferably 2:1.

[0057] In step S1, the organic ligand H 8 The usage ratio of TBPP to the N,N-dimethylformamide can be 5 mg:1-3 mL, preferably 5 mg:2 mL.

[0058] In step S1, the temperature of the solvent thermal reaction can be 150-180° C., and the time can be 12-48 hours.

[0059] In step S1, after the solvothermal reaction is completed, the following post-treatment operation may be performed: the solid product is washed with N,N-dimethylformamide and ethanol, and dried with supercritical carbon dioxide to obtain the metal organic framework material 2.

[0060] In step S2, the mass ratio of the metal organic framework material 2 to the chromium chloride may be 1:6-18.

[0061] In step S2, the concentration of chromium chloride in the chromium chloride N,N-dimethylformamide solution may be 0.4-0.6M.

[0062] In step S2, the temperature of the metal exchange reaction can be 115 to 125°C, and the time can be 12 to 72 hours.

[0063] In step S2, after the metal exchange reaction is completed, the following post-treatment operation can be performed: the solid product is washed with N,N-dimethylformamide, soaked and then cleaned with ethanol, and dried with supercritical carbon dioxide to obtain the pyrene-based metal organic framework material.

[0064] The preparation method provided by the present invention synthesizes the eight-connected pyrene-based ligand H under specific and appropriate conditions. 8 TBPP, then with Cr 3 The metal clusters are used to prepare stable metal organic framework materials under specific and appropriate conditions. The synthesis and preparation methods of the invention are easy to operate and have low cost.

[0065] The metal organic framework material Cr-TBPP-MOF of the present invention can efficiently adsorb methane at low temperatures to achieve natural gas storage and transportation. The metal organic framework material Cr-TBPP-MOF of the present invention is preferably activated before being used for methane adsorption, and the activation operation may include vacuum heating the metal organic framework material at 120°C for more than 6 hours.

[0066] Under LNG-ANG conditions, the low-temperature methane adsorption capacity of the metal-organic framework material Cr-TBPP-MOF can reach 302 cm 3 (STP)cm -3 ,In addition, the excellent performance of Cr-TBPP-MOF during multiple cycles ,demonstrating its potential in practical applications.

[0067] [3] Use of the pyrene-based metal organic framework material according to [1] in methane adsorption. Furthermore, the pyrene-based metal organic framework material can be used in a liquefied natural gas-adsorbed natural gas combined system.

[0068] As a general inventive concept, [4] a methane adsorption method comprises: using the pyrene-based metal organic framework material described in [1] to adsorb methane. Further, the methane adsorption method can use a liquefied natural gas-adsorbed natural gas combined system, and the pyrene-based metal organic framework material can be loaded in the liquefied natural gas-adsorbed natural gas combined system.

[0069] In the application described in [3] and the methane adsorption method described in [4], the conditions of the liquefied natural gas-adsorbed natural gas combined system can be set as follows: 159K, 6 bar; 298K, 5 bar.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] 1. The present invention creatively synthesizes a novel eight-connected pyrene-based organic ligand H 8 TBPP.

[0072] 2. The preparation method of the octa-connected pyrene-based organic ligand provided by the present invention is simple to operate, has high yield and low cost.

[0073] 3. The preparation method of the metal organic framework material provided by the present invention is simple and suitable for large-scale synthesis.

[0074] 4. The metal organic framework material provided by the present invention has a high volumetric methane working capacity and has high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 The organic ligand of the present invention and Cr 3 Metal clusters (Cr 3 Schematic diagram of metal-organic framework materials formed by connecting metals through cluster substitution and coordination.

[0076] Figure 2 The powder X-ray diffraction (PXRD) patterns of the two metal organic framework materials Fe-TBPP-MOF and Cr-TBPP-MOF in Example 3 and the comparison with the simulated PXRD (Simulated line).

[0077] Figure 3 This is a graph showing the nitrogen adsorption / desorption curves of the two metal organic framework materials Fe-TBPP-MOF and Cr-TBPP-MOF in Example 3.

[0078] Figure 4 This is a diagram of the methane adsorption performance of the metal organic framework material Cr-TBPP-MOF in Example 3.

[0079] Figure 5 This is a performance diagram of multiple methane adsorption cycles of the metal organic framework material Cr-TBPP-MOF in Example 3. DETAILED DESCRIPTION

[0080] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0081] Example 1

[0082] Organic ligand H 8 Synthesis method of TBPP:

[0083]

[0084] (1) 1,3,5-tribromobenzene (10.0 g, 32 mmol), (4-(methoxycarbonyl)phenyl)boric acid (15 g, 80 mmol), Na 2 CO 3 (17 g, 160 mmol), [Pd(PPh 3 ) 4 ] (1.5 g, 1.27 mmol) was added to a three-necked flask containing degassed toluene (Toluene)-methanol (MeOH)-water (160:80:80 mL), and refluxed at 80 ° C for 50 h under nitrogen protection. The product was extracted with dichloromethane (160 mL × 3), washed with brine (160 mL), and anhydrous MgSO 4 The filtered solution was dried and evaporated under reduced pressure to obtain the product. The residue was purified by silica gel column chromatography (dichloromethane / petroleum ether=1:4, V / V) to obtain compound 1. Yield: 6.2 g (46%).

[0085] (2) Compound 1 (6.2 g, 14 mmol), bis(pinacolato)diboron (4.1 g, 15.4 mmol) and KOAc (11 g, 108 mmol) were added to dioxane (300 mL) at room temperature under nitrogen for 30 minutes. PdCl 2 (dppf) (0.6 g, 0.8 mmol). The reaction mixture was heated at 90 °C under nitrogen for 12 hours. The mixture was extracted with chloroform (120 mL x 3) and washed with brine (120 mL). The combined organic extracts were washed with anhydrous MgSO 4 Dry and remove the solvent under reduced pressure. The crude product was purified by flash chromatography using dichloromethane / petroleum ether (3:1, V / V) as eluent to give 2 as a white solid. Yield: 5.0 g (73%).

[0086] (3) 1,3,6,8-tetrabromopyrene (0.51 g, 1 mmol), white solid 2 (2.36 g, 5 mmol), and Pd SPhos Gen III catalyst (117 mg, 0.15 mmol) were added to a 250 mL flask. Degassing was performed with nitrogen, and dioxane (80 mL) and K 3 PO 4Aqueous solution (1M, 20mL). Stir the reaction at 90°C for 2 days under a nitrogen atmosphere. Filter the reaction solution, wash with water, and the obtained dark green filtrate is fully dissolved in chloroform. After filtering through diatomaceous earth, chloroform is removed under reduced pressure. The collected yellow-green product (0.5g, 0.32mmol) is suspended in 100mL of a 1:1 volume ratio EtOH and THF mixture in a 250mL round-bottom flask, and then 10mL of 6M NaOH aqueous solution is added. After reflux at 120°C overnight, the organic solvent is removed by rotation, and 4M HCl is slowly added until the pH is about 2, filtered, and the filter cake is washed with water three times and vacuum dried to obtain the organic ligand H 8 TBPP. Yield: 0.44 g (95%).

[0087] Example 2

[0088] Synthesis method of metal organic framework material (Cr-TBPP-MOF):

[0089] Basic ferric acetate (10mg) and organic ligand (5mg) are dissolved in 2mL DMF and 1mL HAc, and put into a 15mL vial. Then, the mixture is ultrasonicated for 3 minutes. The resulting mixture is sealed and heated to 150°C and kept for 12 hours. Golden block crystals are obtained. Harvest crystals and cleaned 6 times with DMF within three days. Then clean the crystals 6 times with EtOH within three days. After cleaning with EtOH, dry the crystals with supercritical carbon dioxide to obtain metal organic framework material 2 (Fe-TBPP-MOF).

[0090] The metal organic framework material 2 (about 50 mg) was transferred to a 15 mL Schlenk tube, and as much DMF as possible was aspirated. The solution was pumped out by the freeze pump, and the cycle was repeated three times. In an argon atmosphere glove box, 400 mg of CrCl 2 Dissolve CrCl in 6 mL DMF 2 / DMF solution was added to the Shrek bottle containing the metal organic framework material 2 crystals, which was then sealed and taken out of the glove box. The resulting mixture was placed in an oven preheated to 120°C for 18 hours. After the vial was cooled to room temperature, the green crystals were collected. The crystalline materials were washed 3 times with DMF and then soaked in DMF overnight. After washing the crystals 6 times with EtOH within three days, the crystals were dried with supercritical carbon dioxide to obtain a high porosity pyrene-based metal organic framework material Cr-TBPP-MOF.

[0091] Example 3

[0092] The metal organic framework material 2 obtained in Example 2 was vacuum activated at room temperature for 6 h, and Cr-TBPP-MOF was vacuum heated and activated at 120°C for 6 h for PXRD test. The results are shown in Figure 2, which are basically consistent with the peak positions of the simulated PXRD curves (Simulated lines), indicating that the designed MOF was successfully prepared with high phase purity.

[0093] The single crystal structure data of the metal organic framework material Cr-TBPP-MOF is shown in Table 1.

[0094] Table 1

[0095]

[0096] The two activated MOFs were used for nitrogen adsorption and desorption tests at 77K. The results are shown in Figure 3 The pore volume of Cr-TBPP-MOF reached 1.31 cm 3 g -1 , and has 3700m 2 g -1 High specific surface area.

[0097] The methane adsorption performance results of Cr-TBPP-MOF are shown in Figure 4 Under LNG-ANG conditions (159K, 6 bar; 298K, 5 bar), the low-temperature methane adsorption capacity of the metal organic framework material is 302 cm 3 (STP)cm -3 .

[0098] Several methane adsorption experiments were conducted on the metal organic framework material Cr-TBPP-MOF. Figure 5 As shown in the figure, the methane adsorption capacity remained basically unchanged in the three rounds, indicating that Cr-TBPP-MOF has excellent recyclability.

[0099] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A pyrene-based metal organic framework material suitable for low-temperature methane adsorption storage, characterized in that: It is formed by substitution coordination connection between organic ligand H8TBPP and Cr3 metal clusters; The organic ligand H8TBPP has the following chemical structure: The Cr3 metal cluster has the chemical structure shown below:

2. The pyrene-based metal organic framework material according to claim 1, characterized in that: The single crystal structure data of the pyrene-based metal organic framework material are as follows:

3. The method for preparing a pyrene-based metal organic framework material according to claim 1 or 2, characterized in that: Includes steps: S1, adding the organic ligand H8TBPP and basic ferric acetate to a mixed solution of N,N-dimethylformamide and acetic acid to carry out a solvothermal reaction to obtain a metal organic framework material 2; S2, adding the metal organic framework material 2 to a chromium chloride N,N-dimethylformamide solution to carry out a metal exchange reaction to obtain the pyrene-based metal organic framework material.

4. The preparation method according to claim 3, characterized in that: The preparation method of the organic ligand H8TBPP comprises the steps of: (1) Under nitrogen protection, 1,3,5-tribromobenzene, (4-(methoxycarbonyl)phenyl)boric acid, Na2CO3, and [Pd(PPh3)4] were added to a degassed mixed solvent of toluene / methanol / water, and the solution was stirred and refluxed. The reaction product was extracted with dichloromethane, washed with brine, dried over anhydrous MgSO4, filtered, and the organic solvent was dried by spin drying. The residue was separated by column chromatography, and the eluent was a mixture of dichloromethane and petroleum ether. The eluent was dried by spin drying to obtain a white solid 1 having the following chemical structure: (2) Under anhydrous and oxygen-free conditions, white solid 1, bis(pinacolato)diboron, KOAc, and PdCl2(dppf) were added to dioxane, and the reaction mixture was heated at 85-95° C. under nitrogen. After the reaction was completed, the mixture was extracted with chloroform and washed with brine. The combined organic extracts were dried over anhydrous MgSO4, filtered, and the organic solvent was dried by spin drying. The crude product was purified by flash column using dichloromethane / petroleum ether as eluent to obtain a white solid 2 having the following chemical structure: (3) Under nitrogen protection, dioxane and K3PO4 aqueous solution were added to 1,3,6,8-tetrabromopyrene, white solid 2 and Pd SPhos Gen III, and the reaction was stirred at 85-95° C. under nitrogen atmosphere. After the reaction was completed, the reaction solution was filtered and washed with water. The obtained dark green filtrate was fully dissolved in chloroform, filtered through diatomaceous earth and the chloroform was removed under reduced pressure. The collected yellow-green product was hydrolyzed with NaOH, refluxed overnight with tetrahydrofuran / ethanol / water as solvent, and the organic solvent was removed by rotation. HCl was added to a pH of 1.5-2.5, filtered, the filter cake was washed with water, and vacuum dried to obtain the organic ligand H8TBPP.

5. The preparation method according to claim 4, characterized in that: In step (1): The molar ratio of 1,3,5-tribromobenzene to (4-(methoxycarbonyl)phenyl)boric acid is 1:2-3; The molar ratio of Na2CO3 to 1,3,5-tribromobenzene is 4 to 6:1; [Pd(PPh3)4] is added at 3% to 6% of the molar amount of 1,3,5-tribromobenzene; The ratio of the mixed solvent toluene / methanol / water to 1,3,5-tribromobenzene is 8-12 mL:1 mmol; The volume ratio of toluene, methanol and water in the mixed solvent toluene / methanol / water is 2:1:1; Na2CO3 is added in the form of a solution, wherein the solvent is water and the concentration of the Na2CO3 solution is 1.5 to 2.5 M; The stirring reflux temperature is 75-85°C; The stirring reflux time is 48 to 52 hours; The eluent used in column chromatography was dichloromethane and petroleum ether in a volume ratio of 1:4; In step (2): The molar ratio of white solid 1 to bis(pinacol)diboron is 1:1 to 1.2; The molar ratio of KOAc to white solid 1 was 7-8:1; PdCl2(dppf) is added at 3% to 6% of 1 mol of white solid; The dosage ratio of dioxane to white solid 1 is 20-22 mL:1 mmol; The heating time at 85-95°C is 10-14 hours; The eluent used in column chromatography was dichloromethane / petroleum ether, with a volume ratio of dichloromethane to petroleum ether of 3:1; In step (3): The molar ratio of 1,3,6,8-tetrabromopyrene to white solid 2 is 1:4-6; Pd SPhos Gen III was added at 14% to 16% of the molar amount of 1,3,6,8-tetrabromopyrene; The ratio of the total volume of dioxane and K3PO4 aqueous solution to the molar amount of 1,3,6,8-tetrabromopyrene is 95-105mL:1mmol; The volume ratio of dioxane to K3PO4 aqueous solution is 3 to 5:1; The concentration of K3PO4 in K3PO4 aqueous solution is 0.9~1.1M; The stirring reaction time is 1.5 to 2.5 days; In the hydrolysis step, the volume ratio of tetrahydrofuran, ethanol, and water in the solvent tetrahydrofuran / ethanol / water is 5:5:1; NaOH is added in the form of a solution, in which the solvent is water and the concentration is 5-7 M; The temperature of the reflux overnight was controlled at 115-125°C.

6. The preparation method according to claim 3, characterized in that: In step S1: The mass ratio of the basic ferric acetate to the organic ligand H8TBPP is not less than 2:1; The volume ratio of N,N-dimethylformamide to acetic acid in the mixed solution of N,N-dimethylformamide and acetic acid is 1.5 to 2.5:1; The usage ratio of the organic ligand H8TBPP and the N,N-dimethylformamide is 5 mg:1-3 mL; The temperature of the solvent thermal reaction is 150-180°C and the time is 12-48h; After the solvothermal reaction is completed, the following post-treatment operation is performed: the solid product is washed with N,N-dimethylformamide and ethanol, and dried with supercritical carbon dioxide to obtain the metal organic framework material 2; In step S2: The mass ratio of the metal organic framework material 2 to the chromium chloride is 1:6-18; The concentration of chromium chloride in the N,N-dimethylformamide solution of chromium chloride is 0.4-0.6M; The temperature of the metal exchange reaction is 115 to 125° C. and the time is 12 to 72 hours; After the metal exchange reaction is completed, the following post-treatment operation is further performed: the solid product is washed with N,N-dimethylformamide, soaked and then cleaned with ethanol, and dried with supercritical carbon dioxide to obtain the pyrene-based metal organic framework material.

7. Use of the pyrene-based metal organic framework material according to claim 1 or 2 in methane adsorption.

8. The use according to claim 7, characterized in that: The pyrene-based metal organic framework material is used in a liquefied natural gas-adsorbed natural gas combined system.

9. A methane adsorption method, characterized in that: include: The pyrene-based metal organic framework material according to claim 1 is used to adsorb methane.

10. The methane adsorption method according to claim 9, characterized in that: The methane adsorption method adopts a liquefied natural gas-adsorbed natural gas combined system, and the pyrene-based metal organic framework material is loaded in the liquefied natural gas-adsorbed natural gas combined system.

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