Copper-based mixed ligand metal organic framework material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metal organic framework materials, and particularly relates to a copper-based mixed ligand metal organic framework material and a preparation method and application thereof. According to the copper-based mixed ligand metal organic framework material provided by the invention, Cu < 2 + > is used as coordination metal, 2, 2 '-bipyridine-5, 5'-dicarboxylic acid and 1, 2, 4-triazole are used as organic ligands, and the copper-based mixed ligand metal organic framework material is of a three-dimensional network structure with a P21 / c space group. The structure of the copper-based mixed ligand metal organic framework material has coordinated water molecules facing the inside of a pore channel, and a large number of open metal sites can be exposed after activation, so that the material has a relatively high specific surface area, and gas molecules such as carbon dioxide and the like can be polarized; the interaction between the material and gases such as carbon dioxide is improved, so that the adsorption capacity and separation selectivity of the gases such as carbon dioxide are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal-organic framework materials, and particularly relates to a copper-based mixed-ligand metal-organic framework material, a preparation method thereof, and an application thereof. Background Art

[0002] In industrial production activities, the combustion of fossil fuels generates flue gas, the main components of which include nitrogen and carbon dioxide. How to selectively separate carbon dioxide from flue gas has attracted wide attention in the industrial community.

[0003] Currently, chemical absorption methods are commonly used in industrial production to treat carbon dioxide in flue gas. Common chemical absorbents are alkaline solutions, such as ammonia water or sodium hydroxide solution, etc. However, chemical absorbents are corrosive, have a large solvent consumption, and high regeneration energy consumption, which do not meet the development requirements of green chemistry.

[0004] In addition, as porous materials, metal-organic framework materials have the potential to adsorb carbon dioxide. However, the specific surface area and separation coefficient of existing metal-organic framework materials are low, the adsorption capacity and selectivity for carbon dioxide are low, and they cannot effectively separate carbon dioxide in flue gas. Summary of the Invention

[0005] The purpose of the present invention is to provide a copper-based mixed-ligand metal-organic framework material, a preparation method thereof, and an application thereof. The copper-based mixed-ligand metal-organic framework material provided by the present invention has strong adsorption selectivity for carbon dioxide, a high adsorption capacity, saves materials, is environmentally friendly, and meets the development requirements of green chemistry.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a copper-based mixed-ligand metal-organic framework material with a structural formula of Cu2(μ2-Cl)(bpydc)(1,2,4-triz)·H2O, where μ2-Cl is a dichloro bridge group, bpydc is 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,2,4-triz is 1,2,4-triazole; the coordinated metal of the copper-based mixed-ligand metal-organic framework material is Cu 2+ , and the organic ligands are 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole.

[0008] Preferably, the Cu 2+ is 5-coordinated.

[0009] Preferably, the chemical formula of the copper-based mixed-ligand metal-organic framework material is Cu2ClC 14 H 10 O5N5, and the topological point symbol is {8 2 .10 4}}。

[0010] Preferably, the specific surface area of the copper-based mixed-ligand metal-organic framework material is 350 - 650 m 2 g -1 , and the actual pore volume is 0.15 - 0.35 cm 3 g -1 。

[0011] The present invention also provides a preparation method of the copper-based mixed-ligand metal-organic framework material described in the above solution, including the following steps:

[0012] Mix a soluble copper salt, an organic ligand, an organic acid, and an organic solvent and carry out a solvothermal reaction to obtain the copper-based mixed-ligand metal-organic framework material; the organic ligand is 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole; the soluble copper salt is copper chloride dihydrate.

[0013] Preferably, the molar ratio of the soluble copper salt to the organic ligand is 2.0:1.4 - 5.5.

[0014] Preferably, the molar ratio of 2,2'-bipyridine-5,5'-dicarboxylic acid to 1,2,4-triazole is 1.0:0.5 - 2.2.

[0015] Preferably, the temperature of the solvothermal reaction is 90 - 200 °C, and the heat preservation time is 12 - 48 h.

[0016] The present invention also provides the application of the copper-based mixed-ligand metal-organic framework material described in the above solution or the copper-based mixed-ligand metal-organic framework material obtained by the preparation method described in the above solution in separating carbon dioxide and nitrogen.

[0017] Preferably, before using the copper-based mixed-ligand metal-organic framework material, it further includes activating the copper-based mixed-ligand metal-organic framework material; the activation includes the following steps: mixing the copper-based mixed-ligand metal-organic framework material with methanol for solvent exchange and then degassing.

[0018] The present invention provides a copper-based mixed-ligand metal-organic framework material. The copper-based mixed-ligand metal-organic framework material provided by the present invention uses Cu 2+ as the coordination metal and 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole as the organic ligands, and is a mixed-ligand metal-organic framework material with a three-dimensional network structure of the P21 / c space group.

[0019] The copper-based mixed-ligand metal-organic framework material provided by the present invention uses Cu 2+ as the coordination metal, Cu 2+As a strong Lewis acid, it can not only form coordination bonds with O and N atoms, easily form MOF materials with diverse structures and adjustable pore sizes with mixed ligands, but also contribute to the structural stability of MOF materials.

[0020] The copper-based mixed-ligand metal-organic framework material provided by the present invention has a nod topology structure, belongs to the monoclinic system, has a novel pore structure, and presents a one-dimensional straight-through ultra-microporous pore channel formed by mononuclear Cu 2+ and mixed ligands inside, and has a large number of open copper metal sites. These metal sites can specifically adsorb carbon dioxide in flue gas, generate a stronger interaction with carbon dioxide gas, and effectively achieve the separation of carbon dioxide and nitrogen.

[0021] In the structure of the copper-based mixed-ligand metal-organic framework material provided by the present invention, there are coordinated water molecules facing the pore channel. After activation, a large number of open metal sites can be exposed, which not only endows the material of the present invention with a high specific surface area, but also can polarize gas molecules such as carbon dioxide, improve the interaction between the material of the present invention and gas molecules such as carbon dioxide, and thus increase the adsorption amount and separation selectivity of the material of the present invention for gas molecules such as carbon dioxide. The results of the examples show that under the conditions of 298K and 101.3kPa, the CO2 adsorption amount is 71.9 cm 3 g -1 , and the separation ratio of CO2 / N2 (15:85, v / v) is 93.6.

[0022] The present invention also provides a preparation method of the copper-based mixed-ligand metal-organic framework material described in the above solution. The preparation method provided by the present invention has the advantages of simple steps, convenient operation, low cost, and easy realization of industrial batch production.

[0023] The present invention also provides the application of the copper-based mixed-ligand metal-organic framework material described in the above solution or the copper-based mixed-ligand metal-organic framework material obtained by the preparation method described in the above solution in carbon dioxide adsorption. The copper-based mixed-ligand metal-organic framework material provided by the present invention has the function of selectively adsorbing carbon dioxide, can collect carbon dioxide through physical adsorption, is especially suitable for treating flue gas, avoids the corrosion of the chemical adsorption method, has a good separation effect on carbon dioxide and nitrogen, and has the advantages of low energy consumption, simple equipment, convenient operation, small environmental impact, and flexible selection of adsorbents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a crystal morphology photo of the copper-based mixed-ligand metal-organic framework material provided by the present invention;

[0026] Figure 2 It is a schematic diagram of the crystal structure of the copper-based mixed-ligand metal-organic framework material provided by the present invention;

[0027] Figure 3 It is the powder X-ray diffraction pattern and the simulated XRD pattern of the structure of the copper-based mixed-ligand metal-organic framework material provided by the present invention;

[0028] Figure 4 It is the single-component adsorption isotherm (298K) of carbon dioxide / nitrogen of the copper-based mixed-ligand metal-organic framework material provided by the present invention;

[0029] Figure 5 It is the adsorption selectivity curve of carbon dioxide / nitrogen of the copper-based mixed-ligand metal-organic framework material provided by the present invention. Detailed implementation manners

[0030] The present invention provides a copper-based mixed-ligand metal-organic framework material with the structural formula Cu2(μ2-Cl)(bpydc)(1,2,4-triz)·H2O, where μ2-Cl is a dichloro bridge group, bpydc is 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,2,4-triz is 1,2,4-triazole; the coordinated metal of the copper-based mixed-ligand metal-organic framework material is Cu 2+ , and the organic ligands are 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole.

[0031] In the present invention, the Cu 2+ can be 5-coordinated, and the Cu 2+ forms a three-dimensional network structure with one-dimensional straight through channels with the organic ligands.

[0032] In the present invention, the chemical formula of the copper-based mixed-ligand metal-organic framework material can be Cu2ClC 14 H 10 O5N5, with the space group of P21 / c, and the topological point symbol can be {8 2 .10 4}.

[0033] In the present invention, the specific surface area of the copper-based mixed-ligand metal-organic framework material can be 350-650 m 2 g -1 , specifically it can be 450 m 2 g -1 or 500 m 2 g-1 The actual pore volume can be 0.15 to 0.35 cm 3 g -1 and specifically can be 0.20 cm 3 g -1 or 0.25 cm 3 g -1 .

[0034] The present invention also provides a method for preparing the copper-based mixed-ligand metal-organic framework material described in the above solution, comprising the following steps:

[0035] Mix a soluble copper salt, an organic ligand, an organic acid and an organic solvent and carry out a solvothermal reaction to obtain the copper-based mixed-ligand metal-organic framework material; the organic ligand is 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole; the soluble copper salt is copper chloride dihydrate.

[0036] In the present invention, the soluble copper salt, the organic ligand, the organic acid and the organic solvent are mixed to obtain a reaction solution. In the present invention, the molar ratio of the soluble copper salt to the organic ligand can be 2.0:1.4 to 5.5, and specifically can be 2.0:1.4, 2.0:1.5, 2.0:1.8, 2.0:2.1, 2.0:2.4, 2.0:2.75, 2.0:3.0, 2.0:3.2, 2.0:3.4, 2.0:3.6, 2.0:3.8, 2.0:4.0, 2.0:4.2, 2.0:4.5, 2.0:4.7, 2.0:4.9, 2.0:5.1, 2.0:5.2, 2.0:5.3, 2.0:5.4 or 2.0:5.5.

[0037] In the present invention, the molar ratio of 2,2'-bipyridine-5,5'-dicarboxylic acid to 1,2,4-triazole can be 1.0:0.5 to 2.2, and specifically can be 1.0:0.5, 1.0:0.6, 1.0:0.7, 1.0:0.8, 1.0:0.9, 1.0:1.0, 1.0:1.1, 1.0:1.2, 1.0:1.3, 1.0:1.4, 1.0:1.5, 1.0:1.6, 1.0:1.7, 1.0:1.8, 1.0:1.9, 1.0:2.0 or 1.0:2.2.

[0038] In the present invention, the organic acid can be an organic carboxylic acid; the organic carboxylic acid can be a C1-C5 organic carboxylic acid; the C1-C5 organic carboxylic acid can include one or more of formic acid, acetic acid and trifluoroacetic acid. In the present invention, the addition of the organic acid plays an inducing role in inducing the assembly of the metal and the ligand and the crystal growth.

[0039] In the present invention, the organic solvent may be an amide solvent; the amide solvent may include one or more of N,N-dimethylformamide, N-methylformamide, and N,N-dimethylacetamide, and more preferably N,N-dimethylformamide.

[0040] In the present invention, the mass ratio of the organic ligand to the organic solvent may be 3-7:1000, specifically 3:1000, 3.1:1000, 3.2:1000, 3.3:1000, 3.4:1000, 3.5:1000, 3.7:1000, 4.0:1000, 4.5:1000, 5.0:1000, 5.5:1000, 6.0:1000, 6.5:1000, or 7.0:1000.

[0041] In the present invention, the volume ratio of the organic solvent to the organic acid may be 100:5-30, specifically 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, 100:16, 100:17, 100:18, 100:19, 100:20, 100:21, 100:22, 100:23, 100:24, 100:25, 100:26, 100:27, 100:28, 100:29, or 100:30.

[0042] In the present invention, the mixing may be ultrasonic mixing; specifically, the mixing may be: adding a soluble copper salt to the organic solvent for the first mixing to obtain a first mixed solution, then adding the organic ligand to the first mixed solution for the second mixing to obtain a second mixed solution, and then adding the organic acid to the second mixed solution for the third mixing.

[0043] After obtaining the reaction solution, the present invention performs a solvothermal reaction on the reaction solution to obtain the copper-based mixed ligand metal-organic framework material. In the present invention, the temperature of the solvothermal reaction may be 90-200°C, specifically 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, and the heat preservation time may be 12-48 h, specifically 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h, 30 h, 32 h, 34 h, 36 h, 38 h, 40 h, 42 h, 44 h, 46 h, or 48 h.

[0044] In the present invention, the equipment for the solvothermal reaction may be a transparent glass bottle with a sealing gasket and an oven; the material of the sealing gasket may be polytetrafluoroethylene.

[0045] In the present invention, after the solvothermal reaction, it may further include successively cooling, washing, and drying the obtained solvothermal reaction product; the cooling can be natural cooling; the final temperature of the cooling can be room temperature; the washing agent used for washing can be an amide solvent; the amide solvent can include one or more of N,N-dimethylformamide, N-methylformamide, and N,N-dimethylacetamide.

[0046] The present invention also provides the application of the copper-based mixed-ligand metal-organic framework material described in the above solution or the copper-based mixed-ligand metal-organic framework material obtained by the preparation method described in the above solution in separating carbon dioxide and nitrogen.

[0047] In the present invention, before using the copper-based mixed-ligand metal-organic framework material, it may further include activating the copper-based mixed-ligand metal-organic framework material.

[0048] In the present invention, the activation may include the following steps: mixing the copper-based mixed-ligand metal-organic framework material with methanol for solvent exchange and then degassing.

[0049] In the present invention, the mixing of the copper-based mixed-ligand metal-organic framework material with methanol can be: immersing the copper-based mixed-ligand metal-organic framework material in methanol until it is completely submerged.

[0050] In the present invention, the temperature of the solvent exchange can be 15 - 30 °C, specifically 15 °C, 20 °C, 25 °C, or 30 °C, and the number of times of solvent exchange can be more than 5 times, specifically 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 15 times, 20 times, or 30 times; the time for a single solvent exchange can be 1 - 3 h, specifically 1 h, 1.5 h, 2 h, 2.5 h, or 3 h.

[0051] In the present invention, the degassing treatment can be carried out under vacuum conditions; the temperature of the degassing treatment can be 80 - 130 °C, specifically 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, or 130 °C, and the heat preservation time can be 8 - 12 h, specifically 8 h, 9 h, 10 h, 11 h, or 12 h.

[0052] In the present invention, when separating carbon dioxide and nitrogen, the volume ratio of carbon dioxide to nitrogen can be 0.15:0.85.

[0053] In the present invention, when separating carbon dioxide and nitrogen, the temperature of the mixed gas of carbon dioxide and nitrogen can be 25 °C.

[0054] To further illustrate the present invention, the solutions of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0055] Example 1

[0056] Under the condition of room temperature (25 °C), 11 mg (0.0645 mmol) of copper chloride dihydrate was dissolved in 0.5 mL of N,N-dimethylformamide, and 4 mg (0.0164 mmol) of 2,2'-bipyridine-5,5'-dicarboxylic acid and 2 mg (0.0290 mmol) of 1,2,4-triazole were dissolved in 1 mL of N,N-dimethylformamide. Then the two solutions were mixed to obtain a mixed solution, and 0.3 mL of acetic acid was added to the mixed solution, and ultrasonic mixing was carried out for 30 s to obtain a reaction solution. The reaction solution was transferred into a transparent glass bottle with a polytetrafluoroethylene sealing gasket, and the transparent glass bottle was placed in an oven at 120 °C for solvothermal reaction for 20 h. Then the transparent glass bottle was taken out and naturally cooled to room temperature, washed with N,N-dimethylformamide and dried to constant weight to obtain a copper-based mixed ligand metal-organic framework material.

[0057] The crystal morphology of the copper-based mixed ligand metal-organic framework material prepared in this example was tested, and the results are as Figure 1 shown. The crystal structure of the copper-based mixed ligand metal-organic framework material prepared in this example is as Figure 2 shown. According to Figure 1 and Figure 2 it can be seen that the copper-based mixed ligand metal-organic framework material prepared in this example has one-dimensional straight through-channels (the one-dimensional straight through-channels are surrounded by blue circles, Figure 2 7 one-dimensional straight through-channels are shown in

[0058] ), and there are coordinated water molecules facing the channels. The activated material will have a high density of open metal sites, ensuring the specific adsorption ability for carbon dioxide. Figure 3 shown. According to Figure 3 it can be seen that the copper-based mixed ligand metal-organic framework material prepared in this example has characteristic diffraction peaks of a simulated single crystal structure, indicating that the material of the present invention is consistent with the crystal structure obtained by simulated single crystal X-ray diffraction and has high crystallinity.

[0059] Example 2

[0060] At room temperature (20 °C), 8 mg (0.0469 mmol) of copper(II) chloride dihydrate, 5 mg (0.0205 mmol) of 2,2'-bipyridine-5,5'-dicarboxylic acid, and 3 mg (0.0435 mmol) of 1,2,4-triazole were dissolved in 2 mL of N,N-dimethylformamide to obtain a mixed solution. Then, 0.5 mL of acetic acid was added to the mixed solution, and the mixture was ultrasonically mixed for 90 s to obtain a reaction solution. The reaction solution was transferred into a transparent glass bottle with a polytetrafluoroethylene sealing gasket, and the transparent glass bottle was placed in an oven at 130 °C for solvothermal reaction for 30 h. Then, the transparent glass bottle was taken out and naturally cooled to room temperature, washed with N,N-dimethylformamide, and dried to a constant weight to obtain a copper-based mixed-ligand metal-organic framework material.

[0061] Example 3

[0062] At room temperature (25 °C), 9 mg (0.0528 mmol) of copper(II) chloride dihydrate, 4.5 mg (0.0185 mmol) of 2,2'-bipyridine-5,5'-dicarboxylic acid, and 2.5 mg (0.0363 mmol) of 1,2,4-triazole were dissolved in 1.5 mL of N,N-dimethylformamide to obtain a mixed solution. Then, 0.4 mL of acetic acid was added to the mixed solution, and the mixture was ultrasonically mixed for 120 s to obtain a reaction solution. The reaction solution was transferred into a transparent glass bottle with a polytetrafluoroethylene sealing gasket, and the transparent glass bottle was placed in an oven at 110 °C for solvothermal reaction for 24 h. Then, the transparent glass bottle was taken out and naturally cooled to room temperature, washed with N,N-dimethylformamide, and dried to a constant weight to obtain a copper-based mixed-ligand metal-organic framework material.

[0063] Application Example 1

[0064] 100 mg of the copper-based mixed-ligand metal-organic framework material prepared in Example 1 was added to 5 mL of methanol for methanol exchange for 48 h (5 mL of methanol was added each time, and the exchange was carried out once every 3 h for a total of 48 h) to obtain a pretreated copper-based mixed-ligand metal-organic framework material; then, in a vacuum drying oven, vacuum degassing was carried out at 110 °C for 10 h to obtain an activated copper-based mixed-ligand metal-organic framework material. The activated copper-based mixed-ligand metal-organic framework material was used to perform a single-component adsorption isotherm test on a carbon dioxide / nitrogen mixed gas (the volume ratio of carbon dioxide to nitrogen was 0.15:0.85), and the test temperature was 25 °C. The results are as Figure 4 and Figure 5 shown. Figure 4 is the single-component adsorption isotherm of carbon dioxide and nitrogen for the copper-based mixed-ligand metal-organic framework material prepared in Example 1, Figure 5 is the adsorption selectivity curve of carbon dioxide / nitrogen for the copper-based mixed-ligand metal-organic framework material prepared in Example 1 calculated by IAST.

[0065] According to Figure 4 and Figure 5 it can be seen that the adsorption isotherms of carbon dioxide and nitrogen both belong to Type I adsorption isotherms. At 25 °C and 1 bar, the adsorption capacity of carbon dioxide reaches 71.9 cm 3 g -1 , while the adsorption capacity of nitrogen is only 6.0 cm 3 g -1 . IAST calculation shows that the adsorption selectivity of the material of the present invention for carbon dioxide in the carbon dioxide / nitrogen mixed gas is 93.6 at 1 bar, which is much higher than many existing MOF materials, such as the reported FJUT-4 (69.3), NKU-521a (51.0) and SCNU-Z4 (17.4).

[0066] It can be known from the above embodiments that the copper-based mixed-ligand metal-organic framework material provided by the present invention has strong adsorption selectivity for carbon dioxide, high adsorption capacity, less material consumption, low cost, environmental friendliness, and meets the development requirements of green chemistry.

[0067] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can also be obtained according to these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A copper-based mixed ligand metal-organic framework material, characterized in that, The structural formula is Cu2(μ2-Cl)(bpydc)(1,2,4-triz)·H2O, where μ2-Cl is a dichloro-bridge group, bpydc is 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,2,4-triz is 1,2,4-triazole; The coordinated metal of the copper-based hybrid ligand metal-organic framework material is Cu 2+ , and the organic ligands are 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole.

2. The copper-based hybrid ligand metal-organic framework material according to claim 1, wherein The described Cu 2+ is 5-coordinated.

3. The copper-based mixed-ligand metal-organic framework material according to claim 1, characterized in that, The chemical formula of the copper-based hybrid ligand metal-organic framework material is Cu2ClC 14 H 10 O5N5, and the topological point symbol is {8 2 .10 4}.

4. The copper-based hybrid ligand metal-organic framework material according to claim 1 or 3, characterized in that, The specific surface area of the copper-based mixed-ligand metal-organic framework material is 350-650 m 2 g -1 , and the actual pore volume is 0.15-0.35 cm 3 g -1 .

5. The preparation method of the copper-based mixed-ligand metal-organic framework material according to any one of claims 1 to 4, characterized in that, It includes the following steps: Mix a soluble copper salt, an organic ligand, an organic acid, and an organic solvent for a solvothermal reaction to obtain the copper-based mixed-ligand metal-organic framework material; The organic ligand is 2,2'-bipyridine-5,5'-dicarboxylic acid and 1,2,4-triazole; The soluble copper salt is copper(II) chloride dihydrate.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the soluble copper salt to the organic ligand is 2.0:1.4 to 5.

5.

7. The preparation method according to claim 5 or 6, characterized in that, The molar ratio of 2,2'-bipyridine-5,5'-dicarboxylic acid to 1,2,4-triazole is 1.0:0.5 to 2.

2.

8. The preparation method according to claim 5, characterized in that, The temperature of the solvothermal reaction is 90 to 200 °C, and the heat preservation time is 12 to 48 h.

9. The application of the copper-based mixed-ligand metal-organic framework material according to any one of claims 1 to 4 or the copper-based mixed-ligand metal-organic framework material obtained by the preparation method according to claims 5 to 8 in the separation of carbon dioxide and nitrogen.

10. The application according to claim 9, wherein Before use, the copper-based mixed-ligand metal-organic framework material further includes activating the copper-based mixed-ligand metal-organic framework material; The activation includes the following steps: Mix the copper-based mixed-ligand metal-organic framework material with methanol for solvent exchange and then degas.

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