Column layer ultra-microporous metal organic framework material, preparation method thereof and application of column layer ultra-microporous metal organic framework material in gas separation

Abstract

The invention discloses a column layer ultra-microporous metal organic framework material and a preparation method and application thereof in gas separation, the chemical formula of the metal organic framework material is [Co3 (BDC-CH3) 3 (DABCO)] n, BDC-CH3 is a first organic ligand 2-methyl-1, 4-phthalic acid, and DABCO is a second organic ligand 1, 4-diazabicyclo [2.2. 2] octane. The pore structure of the column layer ultramicropore metal organic framework material is a triangular pore channel, the column layer ultramicropore metal organic framework material has high adsorption energy and high adsorption capacity for acetylene, regeneration can be achieved, acetylene can be preferentially adsorbed from acetylene / carbon dioxide mixed gas, the adsorption selectivity is relatively high, and therefore efficient separation of acetylene and carbon dioxide is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical separation, and particularly relates to a column-layered ultra-microporous metal-organic framework material, a preparation method thereof, and an application in gas separation. Background Art

[0002] Acetylene (C2H2) is one of the important petrochemical raw materials and is also the basic raw material for manufacturing vinyl chloride, benzene, acrylic acid, synthetic fibers, etc. At the same time, the combustion temperature of acetylene in oxygen can reach 3300 °C, which can be used in the gas welding and cutting industries. Currently, the main methods for producing acetylene are the hydrolysis of calcium carbide and the partial combustion of methane. Among them, carbon dioxide (CO2) is an inevitable impurity, and it must be removed to produce high-purity acetylene for downstream applications. However, acetylene and carbon dioxide have highly similar physical properties, such as molecular size (acetylene: 3.32×3.34×5.7 Å 3 , carbon dioxide: 3.18×3.33×5.36 Å 3 ) and boiling point (acetylene: 189.3 K, carbon dioxide: 194.7 K). In addition, both carbon dioxide and acetylene are non-polar linear molecules. Therefore, separating the C2H2 / CO2 gas mixture is still a highly challenging process. Traditional separation technologies are mainly cryogenic distillation or solvent extraction, but these traditional separation technologies have high energy consumption, high solvent costs, and are not environmentally friendly. To reduce energy consumption and costs, it is necessary to develop a separation technology that can efficiently separate the acetylene-carbon dioxide mixed gas at room temperature and atmospheric pressure.

[0003] Metal-organic frameworks (MOFs) have attracted extensive attention in the fields of adsorption and separation due to their highly tunable porosity, surface polarity, pore size, and topological structure. However, the almost identical kinetic diameters of carbon dioxide and acetylene make it difficult for MOFs to distinguish these gases. Some macroporous volume MOFs with medium pore sizes (7-15 Å) exhibit high gas absorption capacities, but have weak interactions with acetylene molecules, resulting in low C2H2 / CO2 selectivities. An effective method to improve C2H2 / CO2 selectivity is usually to install hydrogen bond acceptors (such as N, O, F active sites) or open metal sites (OMS) in ultra-microporous metal-organic frameworks. However, too strong an interaction between the framework and acetylene gas molecules often leads to high regeneration energy consumption, while small pores often result in low absorption capacities. Therefore, it is of great significance to study a metal-organic framework material with high acetylene adsorption capacity and selectivity and low regeneration energy consumption. Summary of the Invention

[0004] The object of the present invention is to address the above problems and provide a column-layered ultra-microporous metal-organic framework material, a preparation method thereof, and an application in gas separation.

[0005] To achieve its objectives, the present invention adopts the following technical solutions: In the first aspect of the present invention, a columnar-layered ultra-microporous metal-organic framework material is provided. The chemical formula of the metal-organic framework material is [Co3(BDC-CH3)3(DABCO)] n , where: BDC-CH3 is the first organic ligand 2-methyl-1,4-benzenedicarboxylic acid, and DABCO is the second organic ligand 1,4-diazabicyclo[2.2.2]octane.

[0006] The metal-organic framework material [Co3(BDC-CH3)3(DABCO)] n belongs to the monoclinic system, and the space group is I2 / a; the unit cell parameters are: a = 17.56 Å, b = 9.77 Å, c = 27.04 Å, α = 90°, β = 94°, γ = 90°, V = 4628.16.

[0007] The metal-organic framework material [Co3(BDC-CH3)3(DABCO)] n has a pore diameter of 4.4 Å, and its pore structure is a triangular pore channel.

[0008] In the second aspect of the present invention, a preparation method of the above-mentioned columnar-layered ultra-microporous metal-organic framework material is provided, including the following steps: Dissolve the first organic ligand 2-methyl-1,4-benzenedicarboxylic acid and cobalt salt in N,N-dimethylformamide to obtain a mixed solution A, dissolve the second organic ligand 1,4-diazabicyclo[2.2.2]octane in acetonitrile to obtain a mixed solution B, mix and stir the mixed solution A and the mixed solution B, a green precipitate appears, let it stand for sufficient reaction until no more precipitate is produced, filter and remove the precipitate, take the filtrate and place it in a reaction kettle for sufficient reaction, the reaction temperature is 100-130 °C, after the reaction is completed, cool and filter to obtain purple crystals, wash and dry the crystals, and then the metal-organic framework material is obtained.

[0009] In the above technical solution of the preparation method, preferably, the filtrate reacts in the reaction kettle at 100-120 °C for 24-72 h; after the reaction is completed, cool and filter to obtain purple crystals, wash with N,N-dimethylformamide, and then activate and dry to remove the solvent by organic solvent exchange, and then the metal-organic framework material is obtained.

[0010] In the above technical solution of the preparation method, preferably, the purple crystals are washed with N,N-dimethylformamide, and then after multiple organic solvent exchanges, they are activated at a temperature of 80-160 °C and a pressure of 5-6 μmHg for 12-24 h to remove the solvent, and the metal-organic framework material is obtained.

[0011] In the above technical solution of the preparation method, preferably, in the mixed solution of mixed solution A and mixed solution B, the volume ratio of N,N-dimethylformamide to acetonitrile is (8 - 10) : (4 - 7) (preferably 8 - 10 : 5 - 7), and the molar ratio of cobalt salt, 2-methyl-1,4-benzenedicarboxylic acid and 1,4-diazabicyclo[2.2.2]octane is (1 - 1.3) : 1 : (0.8 - 1).

[0012] In the above technical solution of the preparation method, the cobalt salt is cobalt nitrate or cobalt chloride; The organic solvent is selected from at least one or more of acetonitrile, methanol, dichloromethane, acetone and ethanol.

[0013] The third aspect of the present invention provides the application of the column-layered ultra-microporous metal-organic framework material described in any one of the above in the adsorption and separation of acetylene.

[0014] Preferably, the metal-organic framework material is used for separating acetylene / carbon dioxide mixed gas.

[0015] The JNU-13-CH3 prepared by the present invention has a trinuclear pinwheel-shaped secondary building unit (pinwheel SBU). From the structure of the trinuclear pinwheel-shaped secondary building unit, it can be seen that there are two types of cobalt ions in this secondary building unit (denoted as Co1 and Co2 respectively). Co1 adopts a six-coordination mode and coordinates with six O atoms from six different 2-methyl-1,4-benzenedicarboxylic acid ligands respectively, while Co2 adopts a five-coordination mode and coordinates with 4 O atoms from three 2-methyl-1,4-benzenedicarboxylic acid ligands and 1 N atom from one DABCO respectively. Each secondary building unit contains six 2-methyl-1,4-benzenedicarboxylic acid ligands, which are connected to six adjacent secondary building units to form a two-dimensional layer with triangular pores, and the DABCO ligand acts as a pillar between the layers, thus forming a three-dimensional metal-organic framework.

[0016] The JNU-13-CH3 of the present invention is a kind of ultra-microporous metal-organic framework material with a triangular pore structure. Its pore size matches the acetylene molecule, providing a suitable confinement space, and acetylene molecules form a close packing in the pores of JNU-13-CH3, and multiple H δ+ ···C δ- dipole-dipole interactions are formed between acetylene molecules, and there are multiple C-H···O bonds between acetylene molecules and the O atoms of the secondary building unit of the metal-organic framework material; while there are only two weak O···C CO2 van der Waals force interactions between carbon dioxide and the framework. Therefore, acetylene can be preferentially adsorbed from the acetylene / carbon dioxide mixed gas, and the adsorption selectivity is high.

[0017] The beneficial effects of the present invention are as follows: (1) Currently, the conventional methods for improving the C2H2 / CO2 selectivity usually involve installing hydrogen bond acceptors (such as N, O, F active sites) or open metal sites (OMS) in ultra-microporous metal-organic frameworks, which results in a strong interaction with guest molecules and increases the energy consumption for regeneration. In contrast, the structure of the present invention is closely packed, which is more conducive to regeneration.

[0018] Compared with other reported MOFs for C2H2 separation, such as CuI @UiO-66-(COOH)2 (74.5 kJ / mol), ATC-Cu (79.1 kJ / mol), ZNU-1 (54.0 kJ / mol), and NKMOF-1-Ni (60.3 kJ / mol), the isosteric heat of adsorption of acetylene by the JNU-13-CH3 material of the present invention ( Figure 5 ) is 31.61 kJ / mol, which is lower than the above-mentioned reference MOFs. The moderate Qst value of the material of the present invention ensures that under ambient conditions, the material can preferentially adsorb C2H2 and can also be regenerated.

[0019] (2) The pore surface of the material of the present invention is composed of organic ligands 2-methyl-1,4-benzenedicarboxylic acid (BDC-CH3) and 1,4-diazabicyclo[2.2.2]octane (DABCO). The insertion of the methyl group in BDC-CH3 results in a strong interaction between the pore surface of the material and acetylene molecules, ensuring that the material has a strong adsorption energy and a high adsorption capacity for acetylene. Generally speaking, a large pore volume has a high adsorption capacity, while a small pore volume has a low adsorption capacity. However, the JNU-13-CH3 of the present invention has a relatively high adsorption capacity despite having a small pore volume. The JNU-13-CH3 of the present invention is an ultra-microporous metal-organic framework with a theoretical pore volume of 0.314 cm 3 / g, and the measured pore volume is 0.308 cm 3 / g. The nitrogen adsorption capacity at 77K is 200 cm 3 / g, but it has an acetylene adsorption capacity of 95 cm 3 / g.

[0020] (3) The material of the present invention has an appropriate pore size (4.4 Å), providing a confined adsorption space for further strengthening the interaction between acetylene molecules and the framework. The material of the present invention can preferentially adsorb acetylene from the acetylene / carbon dioxide mixed gas, and the adsorption selectivity is relatively high, thus realizing the efficient separation of acetylene and carbon dioxide.

[0021] (4) The organic ligands 2-methyl-1,4-benzenedicarboxylic acid and 1,4-diazabicyclo[2.2.2]octane used in the synthesis of the material of the present invention have simple structures and relatively low costs in the ligand materials.

[0022] (5)Based on the pillar-layer structure foundation of the materials of the present invention, the organic ligand 2-methyl-1,4-benzenedicarboxylic acid can be replaced with ligands of the same type (such as 1,4-benzenedicarboxylic acid, 2-methoxy-1,4-benzenedicarboxylic acid), and the pillar ligands can be replaced with ligands of the same type but different sizes (such as pyrazine, 4,4'-bipyridine), so as to construct a series of isostructural microporous cobalt-based MOFs, providing a material basis for accurately studying the structure-activity relationship and dealing with more gas separation systems. Description of the Drawings

[0023] Figure 1 It is the topological structure diagram of the JNU-13-CH3 metal-organic framework material prepared in Example 1.

[0024] Figure 2 It is the N2 adsorption / desorption isotherm of JNU-13-CH3 at 77K.

[0025] Figure 3 It is the adsorption / desorption isotherm of C2H2 and CO2 of JNU-13-CH3 at 298K.

[0026] Figure 4 It is the powder X-ray spectrum of JNU-13-CH3 (simulated powder X-ray diffraction spectrum and powder X-ray diffraction spectra before and after activation).

[0027] Figure 5 It is the isosteric heat of adsorption Qst of the JNU-13-CH3 metal-organic framework material with acetylene and carbon dioxide.

[0028] Figure 6 It is the column cycle separation breakthrough curve (298K, 1 bar) of the JNU-13-CH3 metal-organic framework material for the mixed gas of C2H2 / CO2 (v:v = 50:50) with flow rates of 1, 2, 3, and 4 mL / min respectively.

[0029] Figure 7 It is the column cycle separation breakthrough curve (298K, 1 bar) of the JNU-13-CH3 metal-organic framework material for the mixed gas of C2H2 / CO2 (v:v = 50:50, total flow rate of 2 mL / min) at different humidities.

[0030] Figure 8 It is the schematic diagram of the interaction between the JNU-13-CH3 metal-organic framework material and acetylene molecules.

[0031] Figure 9 It is the schematic diagram of the interaction between the JNU-13-CH3 metal-organic framework material and carbon dioxide molecules.

[0032] Figure 10It is the X-ray spectrum of the metal-organic framework material powder prepared in Examples 1-4.

[0033] Figure 11 It is the powder X-ray spectrum (a) and the N2 adsorption-desorption isotherm curve (b) of JNU-13-H prepared in Comparative Example 1. Detailed implementation manners

[0034] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

[0035] The main raw materials and their sources in each embodiment of the present invention are as follows: Cobalt nitrate hexahydrate, CAS No.: 10026-22-9, chemical formula: Co(NO3)2·6H2O; 2-Methyl-1,4-benzenedicarboxylic acid (H2BDC-CH3): CAS No.: 5156-01-4, chemical formula: C9H8O4; N,N-Dimethylformamide (DMF): CAS No.: 68-12-2, chemical formula: C3H7NO; 1,4-Diazabicyclo[2.2.2]octane (DABCO): alias: triethylenediamine, CAS No.: 280-57-9, chemical formula: C6H 12 N2; Acetonitrile: CAS No.: 75-05-8, chemical formula: C2H3N.

[0036] The above raw materials are all commercially available conventional chemical raw materials and are all of laboratory analytical purity.

[0037] Example 1 Preparation of the column-layered ultra-microporous metal-organic framework material of the present invention The preparation method is carried out according to the following steps: Dissolve cobalt(II) nitrate hexahydrate (1.3 mmol, 378.3 mg) and 2-methyl-1,4-benzenedicarboxylic acid (1.3 mmol, 234.2 mg) in 10 mL of N,N-dimethylformamide, and stir with ultrasonic vibration until completely dissolved; dissolve 1,4-diazabicyclo[2.2.2]octane (0.8 mmol, 90 mg) in 5 mL of acetonitrile, and stir with ultrasonic vibration until completely dissolved; mix the two obtained solutions and stir evenly (for about dozens of seconds), a green precipitate appears, let it stand for 2 - 3 hours, then filter off the green precipitate (impurities), take the filtrate and place it in a 20 ml thick-walled pressure-resistant bottle, heat it in an oven to 100 °C and keep it warm for 36 h, cool to room temperature after the reaction is completed, filter to obtain purple parallelogram-shaped crystals, wash the obtained purple crystals with N,N-dimethylformamide until the solution is clear, then exchange with acetonitrile for three days, with at least three exchanges per day, and then activate it at 80 °C and a pressure of 6 μmHg for 12 h to remove solvent molecules, obtaining the metal-organic framework material of the present invention, abbreviated as JNU-13-CH3.

[0038] JNU-13-CH3 was tested. Single-crystal X-ray diffractometer tests showed that the purple crystal was the target compound. The X-ray single-crystal diffraction data was collected in an ω-scan mode on an XtaLAB PRO MM007-DW single-crystal diffractometer system. The X-ray generator used was RA-Micro7HF-MR-DW (Cu / Mo), and the detector was HyPix-6000HE Hybrid Photon Counting (HPC). The "crystallographic parameters" of the compound were: a = 17.56 Å, b = 9.77 Å, c = 27.04 Å, α = 90°, β = 94°, γ = 90°. The pore size of the metal-organic framework material was 4.4 Å. The molecular formula was [Co3(BDC-CH3)3(DABCO)] n , where BDC-CH3 is 2-methyl-1,4-benzenedicarboxylic acid and DABCO is 1,4-diazabicyclo[2.2.2]octane.

[0039] The crystal structure topology diagram of the JNU-13-CH3 metal-organic framework material is as Figure 1 shown. It can be seen from the figure that JNU-13-CH3 has triangular channels along the c-axis direction.

[0040] The JNU-13-CH3 was tested for N2 adsorption at 77 K using a Micromeritics ASAP 2020 Plus Accelerated Surface Area and Porosimetry analyzer. Its N2 isothermal adsorption curve is asFigure 2 As shown, its specific surface area is 605 m 2 / g.

[0041] The isothermal adsorption curves of C2H2 and CO2 of JNU-13-CH3 metal-organic framework material at 298 K are as Figure 3 shown. It can be seen from Figure 3 that the JNU-13-CH3 material preferentially adsorbs acetylene gas, and the adsorption amount is significantly higher than that of carbon dioxide. At 298 K and 100 kPa, the adsorption amounts of the metal-organic framework for acetylene and carbon dioxide are 95 and 55 cm 3 / g respectively, that is, the adsorption of acetylene is much higher than that of carbon dioxide. And JNU-13-CH3 has good solvent stability and thermal stability. For the equicomponent acetylene-carbon dioxide mixture, in the pressure range of 1-100 kPa, the IAST selectivity of acetylene-carbon dioxide is about 5.1. The adsorption selectivity of JNU-13-CH3 for acetylene mainly comes from the close packing of acetylene molecules in the appropriate pore size, and there are multiple H δ+ ···C δ- dipole-dipole interactions between guest molecules, and there are multiple C-H···O bonds between the guest and the O atom of the secondary building unit of the host framework.

[0042] Figure 4 is the powder X-ray spectrum of JNU-13-CH3. It can be seen from Figure 4 that the synthesized JNU-13-CH3 sample is in good agreement with the simulated PXRD spectrum, which proves the phase purity of JNU-13-CH3, and the crystallinity of the activated sample remains good, indicating that JNU-13-CH3 has good stability.

[0043] The crystallographic data of JNU-13-CH3 are shown in Table 1 as follows: Table 1

[0044] The isothermal adsorption heats of JNU-13-CH3 metal-organic framework material with acetylene and carbon dioxide are as Figure 5 shown. It can be seen from Figure 5 that the isothermal adsorption heat of acetylene and the metal-organic framework material is significantly higher than that of carbon dioxide and the framework, which further illustrates that the metal-organic framework material preferentially adsorbs acetylene.

[0045] The breakthrough curves of JNU-13-CH3 at different flow rates under ambient conditions at room temperature are as Figure 6As shown, it can be seen from the figure that under the environmental conditions of room temperature, JNU-13-CH3 can completely separate the C2H2 / CO2 mixture at different flow rates to obtain high-purity acetylene. The breakthrough curves of JNU-13-CH3 at different humidities under the environmental conditions of room temperature are as Figure 7 shown. Under the environmental conditions of room temperature, JNU-13-CH3 can completely separate the C2H2 / CO2 mixture at different humidities to obtain high-purity acetylene without obvious loss.

[0046] Schematic diagrams of the interactions between the JNU-13-CH3 metal-organic framework material and acetylene molecules and carbon dioxide molecules are respectively as Figure 8 and 9 shown. It can be seen from the figure that there are multiple interaction forces between acetylene molecules and between acetylene and the framework: acetylene molecules form close packing in the pores of JNU-13-CH3, and multiple H δ+ ···C δ- dipole-dipole interactions are formed between acetylene molecules, and multiple C-H···O bonds exist between acetylene molecules and the O atoms of the secondary building units of the metal-organic framework material; while there are only two weak O···C CO2 van der Waals force interactions between carbon dioxide and the framework; therefore, the material JNU-13-CH3 preferentially adsorbs acetylene.

[0047] Example 2 The preparation method is operated according to the following steps: Dissolve cobalt nitrate hexahydrate (1.3 mmol, 378.3 mg) and 2-methyl-1,4-benzenedicarboxylic acid (1.3 mmol, 234.2 mg) in 10 mL of N,N-dimethylformamide, and stir with ultrasonic vibration until completely dissolved; dissolve 1,4-diazabicyclo[2.2.2]octane (1 mmol, 112 mg) in 5 mL of acetonitrile, and stir with ultrasonic vibration until completely dissolved; mix the two obtained solutions and stir evenly to form a green precipitate. Let it stand for 2 - 3 hours, then filter off the green precipitate (impurities), take the filtrate and place it in a 20 ml thick-walled pressure-resistant bottle, put it in an oven and heat it to 100 °C for heat preservation reaction for 72 h. After the reaction is completed, cool it to room temperature, filter to obtain purple parallelogram-shaped crystals. Wash the obtained purple crystals with N,N-dimethylformamide until the solution is clear, and then exchange with acetonitrile for three days, with at least three exchanges per day. Then activate it at 80 °C and an atmospheric pressure of 6 μmHg for 12 h to remove solvent molecules to obtain the metal-organic framework material of the present invention.

[0048] Example 3 The preparation method is carried out according to the following steps: Dissolve cobalt(II) nitrate hexahydrate (1.3 mmol, 378.3 mg) and 2-methyl-1,4-benzenedicarboxylic acid (1.3 mmol, 234.2 mg) in 10 mL of N,N-dimethylformamide, and stir with ultrasonic vibration until completely dissolved; dissolve 1,4-diazabicyclo[2.2.2]octane (0.8 mmol, 90 mg) in 5 mL of acetonitrile, and stir with ultrasonic vibration until completely dissolved; mix the two obtained solutions and stir evenly to form a green precipitate. Let it stand for 2 - 3 hours, then filter off the green precipitate (impurities). Take the filtrate and place it in a 20 mL thick-walled pressure-resistant bottle, heat it in an oven to 120 °C and keep it reacting for 24 h. After the reaction is completed, cool it to room temperature, filter to obtain purple parallelogram-shaped crystals. Wash the obtained purple crystals with N,N-dimethylformamide until the solution is clear, then exchange with acetonitrile for three days, with at least three exchanges per day. Then activate it at 80 °C and a pressure of 6 μmHg for 12 h to remove solvent molecules, obtaining the metal-organic framework material of the present invention.

[0049] Example 4 The preparation method is carried out according to the following steps: Dissolve cobalt(II) nitrate hexahydrate (1.3 mmol, 378.3 mg) and 2-methyl-1,4-benzenedicarboxylic acid (1.3 mmol, 234.2 mg) in 8 mL of N,N-dimethylformamide, and stir with ultrasonic vibration until completely dissolved; dissolve 1,4-diazabicyclo[2.2.2]octane (0.8 mmol, 90 mg) in 7 mL of acetonitrile, and stir with ultrasonic vibration until completely dissolved; mix the two obtained solutions and stir evenly to form a green precipitate. Let it stand for 2 - 3 hours, then filter off the green precipitate (impurities). Take the filtrate and place it in a 20 mL thick-walled pressure-resistant bottle, heat it in an oven to 100 °C and keep it reacting for 36 h. After the reaction is completed, cool it to room temperature, filter to obtain purple parallelogram-shaped crystals. Wash the obtained purple crystals with N,N-dimethylformamide until the solution is clear, then exchange with acetonitrile for three days, with at least three exchanges per day. Then activate it at 80 °C and a pressure of 6 μmHg for 12 h to remove solvent molecules, obtaining the metal-organic framework material of the present invention.

[0050] Figure 10 It is the powder X-ray spectrum of the metal-organic framework material prepared in Examples 1 - 4. It can be seen from the powder X-ray diffraction pattern that the samples prepared in Examples 1 - 4 are the same column-layered ultra-microporous metal-organic framework material [Co3(BDC-CH3)3(DABCO)] n 。

[0051] Comparative Example 1 Preparation of MOF samples with different organic ligands Replace the organic ligand 2-methyl-1,4-benzenedicarboxylic acid in Example 1 with 1,4-benzenedicarboxylic acid, and the preparation method is operated according to the following steps: Dissolve cobalt(II) nitrate hexahydrate (1.3 mmol, 378.3 mg) and 1,4-benzenedicarboxylic acid (1.3 mmol, 216 mg) in 10 mL of N,N-dimethylformamide, and stir with ultrasonic vibration until completely dissolved; dissolve 1,4-diazabicyclo[2.2.2]octane (1 mmol, 112 mg) in 5 mL of acetonitrile, and stir with ultrasonic vibration until completely dissolved; mix the two obtained solutions and stir evenly to form a green precipitate, let it stand for 2 - 3 hours, then filter off the green precipitate (impurities), take the filtrate and place it in a 20 ml thick-walled pressure-resistant bottle, heat it in an oven to 100 °C and keep the reaction for 36 h, cool to room temperature after the reaction is completed, filter to obtain purple parallelogram-shaped crystals, wash the obtained purple crystals with N,N-dimethylformamide until the solution is clear, then exchange with acetonitrile for three days, with at least three exchanges per day, and then activate at 80 °C and a pressure of 6 μmHg for 12 h to remove solvent molecules to obtain a metal-organic framework material, abbreviated as JNU-13-H.

[0052] The powder X-ray spectrum of JNU-13-H ( Figure 11 Figure a in Figure 11 and the 77K N2 adsorption-desorption isotherm curve ( Figure 11 Figure b in Figure 4 show that the stability of JNU-13-H prepared in Comparative Example 1 is worse than that of Example 1 ( Figure 11 comparing Figure a in Figure 4 ), which is because the ligand in Example 1 has the insertion of a hydrophobic group methyl, thus improving the stability of Example 1. Due to the poor stability of Comparative Example 1, therefore, the 77K N2 adsorption-desorption experiment of JNU-13-H also shows test results of unstable samples, and the nitrogen adsorption amount is much lower than the theoretical adsorption amount ( Figure 11 Figure b in Figure 4 ), while the theoretical adsorption amount and the measured adsorption amount in Example 1 are basically in agreement.

Claims

1. A column-layered ultra-microporous metal-organic framework material, characterized in that: The chemical formula of the metal-organic framework material is [Co3(BDC-CH3)3(DABCO)] n , where BDC-CH3 is the first organic ligand 2-methyl-1,4-benzenedicarboxylic acid, and DABCO is the second organic ligand 1,4-diazabicyclo[2.2.2]octane.

2. The column-layered ultra-microporous metal-organic framework material according to claim 1, wherein: The metal-organic framework material [Co3(BDC-CH3)3(DABCO)] n belongs to the monoclinic system with the space group I2 / a; the unit cell parameters are: a = 17.56 Å, b = 9.77 Å, c = 27.04 Å, α = 90°, β = 94°, γ = 90°, V = 4628.

16.

3. The pillar-layered ultra-microporous metal-organic framework material according to claim 1, wherein: The metal-organic framework material [Co3(BDC-CH3)3(DABCO)] n has a pore size of 4.4 Å and its pore structure is a triangular pore channel.

4. The preparation method of the column-layered ultra-microporous metal-organic framework material according to any one of claims 1 to 3, characterized in that, It includes the following steps: Dissolve the first organic ligand 2-methyl-1,4-benzenedicarboxylic acid and cobalt salt in N,N-dimethylformamide to obtain a mixed solution A, dissolve the second organic ligand 1,4-diazabicyclo[2.2.2]octane in acetonitrile to obtain a mixed solution B, mix and stir the mixed solution A and the mixed solution B, and a green precipitate appears. Let it stand to fully react until no more precipitate is produced. Filter off the precipitate, take the filtrate and place it in a reaction kettle for full reaction. The reaction temperature is 100-130 °C. After the reaction is completed, cool and filter to obtain purple crystals. Wash and dry the crystals to obtain the metal-organic framework material.

5. The preparation method according to claim 4, characterized in that: The filtrate reacts in the reaction kettle at 100-120 °C for 24-72 h; after the reaction is completed, cool and filter to obtain purple crystals, wash them with N,N-dimethylformamide, and then carry out activation by organic solvent exchange and dry to remove the solvent to obtain the metal-organic framework material.

6. The preparation method according to claim 5, characterized in that: The purple crystals are washed with N,N-dimethylformamide, and then after multiple organic solvent exchanges, they are activated at a temperature of 80-160 °C and a pressure of 5-6 μmHg under atmospheric pressure for 12-24 h to remove the solvent to obtain the metal-organic framework material.

7. The preparation method according to claim 4, characterized in that: In the mixed solution of the mixed solution A and the mixed solution B, the volume ratio of N,N-dimethylformamide to acetonitrile is (8-10) : (4-7), and the molar ratio of cobalt salt, 2-methyl-1,4-benzenedicarboxylic acid and 1,4-diazabicyclo[2.2.2]octane is (1-1.3) : 1 : (0.8-1).

8. The preparation method according to claim 5, characterized in that: The cobalt salt is cobalt nitrate or cobalt chloride; The organic solvent is selected from at least one or more of acetonitrile, methanol, dichloromethane, acetone and ethanol.

9. Use of the column-layered ultra-microporous metal-organic framework material according to any one of claims 1 to 3 in the adsorption and separation of acetylene.

10. The application according to claim 9, characterized in that: The metal-organic framework material is used for separating acetylene / carbon dioxide mixed gas.

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