Imidazole-based metal organic framework nanomaterial and preparation method and application thereof
By preparing imidazole-based metal-organic framework nanomaterials, the problem of difficulty in selective adsorption of carbon dioxide in existing technologies was solved, and efficient and low-cost carbon dioxide enrichment effects were achieved.
Patent Information
- Application Number
- CN202410839577.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-26
- Publication Date
- 2025-10-10
- Estimated Expiration
- 2044-06-26
AI Technical Summary
Existing metal-organic framework materials are difficult to effectively and selectively adsorb carbon dioxide from mixed gases at low concentrations, and existing methods are complex or costly to operate.
Using imidazole-based metal-organic framework nanomaterials, a nanomaterial with a cage-like pore structure was prepared by reacting metal salts with 4,5-dicyanoimidazole at normal pressure, which was used to physically adsorb carbon dioxide to form an enrichment device.
It achieves highly selective adsorption and enrichment of carbon dioxide, has large adsorption capacity, simple operation, low cost, good repeatability, and is suitable for the enrichment of low-concentration carbon dioxide.
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Figure CN119019698B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of porous materials, in particular to an imidazole-based metal organic framework nanomaterial and a preparation method and application thereof. Background Art
[0002] Carbon dioxide (CO2) is widely present in the atmosphere and strata of the Earth and other planets, and plays an extremely important role in human life and the origin of life. Carbon dioxide not only maintains the stability of the human body's internal environment and provides nutrients for plants to photosynthesize, but also affects climate change. The capture and enrichment of carbon dioxide is of great significance to the maintenance of living organisms, the exploration of the origin of life, and the protection of the natural environment. However, the low concentration of carbon dioxide in nature poses a challenge to the enrichment of carbon dioxide. At present, the main methods for separating or enriching carbon dioxide include absorption, adsorption, catalysis, and biological fixation. Among them, adsorption, as a physical method, has the advantages of high selectivity, large adsorption capacity, simple process, and low cost, and is favored by many researchers.
[0003] Metal-organic frameworks (MOFs) have the characteristics of large specific surface area, adjustable pore size, and diverse structures, and have attracted widespread attention in the fields of gas adsorption, storage, and enrichment. However, the MOF materials reported so far have insufficient recognition ability for carbon dioxide, making it difficult to effectively and selectively adsorb carbon dioxide from mixed gases at low concentrations. By selecting new organic ligands to construct CO2-philic MOFs, the selectivity of MOFs for CO2 can be effectively improved. In addition, the development of simple synthetic methods to prepare MOF nanocrystals will facilitate the processing of MOFs into enrichment devices, thereby better utilizing MOFs' role in CO2 enrichment. Summary of the Invention
[0004] The present application aims to overcome the deficiencies in the prior art and provide an imidazole-based metal organic framework nanomaterial, a preparation method and application thereof; the preparation method and process provided by the invention are simple, and the prepared imidazole-based metal organic framework nanomaterial has high adsorption selectivity for low-concentration carbon dioxide and excellent enrichment performance.
[0005] The above technical objectives of the present invention are achieved through the following technical solutions:
[0006] An imidazole-based metal organic framework nanomaterial comprises a metal salt and an organic ligand; the organic ligand is 4,5-dicyanoimidazole.
[0007] Preferably, the metal ions in the metal salt include zinc ions or cobalt ions.
[0008] When the metal ion is a zinc ion, the chemical structure obtained by the reaction of the metal salt with 4,5-dicyanoimidazole is as follows:
[0009]
[0010] When the metal ion is a cobalt ion, the chemical structure obtained by the reaction of the metal salt with 4,5-dicyanoimidazole is as follows:
[0011]
[0012] More preferably, the metal salt is one or more of zinc nitrate, zinc acetate, cobalt nitrate and cobalt acetate; most preferably, zinc acetate or cobalt acetate.
[0013] Preferably, the molar ratio of the metal ion to the organic ligand is 1:(1.5-6); more preferably 1:(1-5); and most preferably 1:2.
[0014] Preferably, the nanomaterial is a structure with a grain size of 50 to 200 nm.
[0015] In addition, to achieve the above-mentioned purpose, the present invention also provides a method for preparing an imidazole-based metal organic framework nanomaterial, which is specifically: mixing a metal salt, an organic ligand and an organic solvent under normal pressure and stirring, carrying out a coordination reaction at a certain temperature, and then centrifuging, washing and drying in sequence to obtain an imidazole-based metal organic framework nanomaterial.
[0016] Preferably, the organic solvent includes N,N-dimethylformamide, methanol, water, or N,N-dimethylformamide / water or N,N-dimethylformamide / methanol. More preferably, it is N,N'-dimethylformamide or N,N'-dimethylformamide / methanol; and most preferably, it is N,N'-dimethylformamide / methanol.
[0017] Preferably, the coordination reaction temperature is 25-60°C and the reaction time is 24-96 hours. The temperature is more preferably 40-60°C, and most preferably 50-60°C. The reaction time is more preferably 24-72 hours, and most preferably 48-72 hours.
[0018] In addition, to achieve the above-mentioned purpose, the present invention also provides an application of an imidazole-based metal organic framework nanomaterial in the selective adsorption of carbon dioxide.
[0019] Preferably, the concentration of carbon dioxide and nitrogen in static adsorption is 99.9% or 99.99%;
[0020] Preferably, the concentration of carbon dioxide in nitrogen during dynamic adsorption is 1 ppm, 10 ppm and 100 ppm.
[0021] In addition, to achieve the above-mentioned purpose, the present invention also provides an application of an imidazole-based metal-organic framework in a low-concentration carbon dioxide concentrator. The preparation method of the low-concentration carbon dioxide concentrator is as follows:
[0022] The prepared imidazole-based metal organic framework nanomaterial is dispersed in an anhydrous organic solvent, and then the obtained dispersion is deposited on a component to form a thin film. After removing the solvent, the concentrator is obtained.
[0023] The enricher is preferably used as a selective enrichment device for carbon dioxide in a carbon dioxide-nitrogen mixed system.
[0024] Preferably, the concentration of the dispersion is 5 to 30 mg / mL. More preferably, it is 10 to 25 mg mL -1 , most preferably 15-25 mg mL -1 .
[0025] Preferably, the thickness of the film is ≤60 μm.
[0026] Preferably, the thin film is deposited by spin coating or drop coating.
[0027] In addition, the concentration of the low concentration carbon dioxide is ≤100ppm
[0028] Preferably, the anhydrous organic solvent includes one or more of anhydrous methanol, anhydrous acetonitrile, and anhydrous dichloromethane, more preferably anhydrous methanol and acetonitrile, and most preferably methanol.
[0029] Preferably, during the process of removing the solvent, heating is used, and the heating method includes vacuum heating or nitrogen flow heating.
[0030] Preferably, the heating temperature for removing the solvent is 80-180°C for 6-24 hours, more preferably 100-150°C, and most preferably 120-150°C; and the heating time is more preferably 12-24 hours, and most preferably 12-18 hours.
[0031] Preferably, the element is a silicon wafer, organic glass or aluminum wafer.
[0032] Compared with the prior art, the present invention has the following beneficial effects:
[0033] 1. The imidazole-based metal organic framework nanomaterial prepared by the present invention has a cage-like pore structure, wherein the cyano group in the cage can recognize carbon dioxide and has a high adsorption selectivity for carbon dioxide. As shown in the results of the examples of the present invention, the imidazole-based metal organic framework material provided by the present invention has a CO2 / N2 adsorption selectivity of up to 195 and a carbon dioxide enrichment factor of up to 1480. The framework has a cage-like structure, and the cavity of the cage can accommodate a large number of carbon dioxide molecules, thereby increasing the adsorption capacity for carbon dioxide. As shown in the results of the examples of the present invention, the imidazole-based metal organic framework material provided by the present invention has an adsorption capacity of 36.2 cm2 of carbon dioxide. 3 / g, and the carbon dioxide enrichment amount at a low concentration is up to 0.03 cm 3 / g.
[0034] 2. The absorption method is to use the different solubility of components in the solvent to enrich, but it needs to consume a large amount of solvent. The catalytic method is to use the catalyst to convert the target component into other components, which is not only irreversible, but also needs expensive catalysts. The biological fixation method is to use bacteria or plants to convert into chemical substances, which is generally irreversible, and takes a very long time. Compared with the above methods, the present application uses imidazole-based metal organic framework material as a selective carbon dioxide enrichment agent, and uses physical adsorption to enrich carbon dioxide in carbon dioxide-nitrogen mixed gas, which has the advantages of simple operation, high selectivity, large adsorption capacity and high repeatability. BRIEF DESCRIPTION OF DRAWINGS
[0035] Figure 1 is a crystal structure diagram of Zn(CN-IM)2 and Co(CN-IM)2;
[0036] Figure 2 is an X-ray diffraction pattern of Zn(CN-IM)2 powder prepared in Example 1;
[0037] Figure 3 is an infrared spectrum of Zn(CN-IM)2 powder prepared in Example 1;
[0038] Figure 4 is a thermogravimetric curve of Zn(CN-IM)2 powder prepared in Example 1;
[0039] Figure 5 is a scanning electron microscope photograph of the front and cross section of the film of Zn(CN-IM)2 powder prepared in Example 1;
[0040] Figure 6 is an adsorption curve of carbon dioxide and nitrogen of Zn(CN-IM)2 powder prepared in Example 1;
[0041] Figure 7 is an adsorption selectivity graph of carbon dioxide and nitrogen of Zn(CN-IM)2 powder prepared in Example 1;
[0042] Figure 8 is an X-ray diffraction pattern of Co(CN-IM)2 powder prepared in Example 2;
[0043] Figure 9 is an infrared spectrum of Co(CN-IM)2 powder prepared in Example 2;
[0044] Figure 10 is a thermogravimetric curve of Co(CN-IM)2 powder prepared in Example 2;
[0045] Figure 11 Scanning electron microscope photos of the front surface of the Co(CN-IM)2 powder and the cross section of the film prepared in Example 2;
[0046] Figure 12 This is a graph showing the adsorption of carbon dioxide and nitrogen by the Co(CN-IM)2 powder prepared in Example 2;
[0047] Figure 13 This is a graph showing the adsorption selectivity of carbon dioxide to nitrogen for the Co(CN-IM)2 powder prepared in Example 2;
[0048] Figure 14 This is the X-ray diffraction pattern of the Zn / Co(CN-IM)2 powder prepared in Example 3;
[0049] Figure 15 This is the infrared spectrum of the Zn / Co(CN-IM)2 powder prepared in Example 3;
[0050] Figure 16 This is a thermogravimetric curve of the Zn / Co(CN-IM)2 powder prepared in Example 3;
[0051] Figure 17 Scanning electron microscope photos of the front surface of the Zn / Co(CN-IM)2 powder and the cross section of the film prepared in Example 3;
[0052] Figure 18 This is a graph showing the adsorption of carbon dioxide and nitrogen by the Zn / Co(CN-IM)2 powder prepared in Example 3;
[0053] Figure 19 This is a graph showing the adsorption selectivity of carbon dioxide to nitrogen for the Zn / Co(CN-IM)2 powder prepared in Example 3;
[0054] Figure 20 Figures for Zn(CN-IM)2, Co(CN-IM)2, and Zn / Co(CN-IM)2 thin film assemblies;
[0055] Figure 21 Schematic diagram of the apparatus used in the experiment of enriching carbon dioxide in carbon dioxide / nitrogen mixture. DETAILED DESCRIPTION
[0056] The preparation of the imidazolyl metal organic framework material described in this application is further described in detail below in conjunction with specific embodiments.
[0057] Example 1
[0058] (1) Under normal pressure and stirring, zinc acetate (Zn(CH3COO)2, 91.5 mg, 0.5 mmol) and 4,5-dicyanoimidazole (C5H2N4, 113.3 mg, 0.96 mmol) were added to a glass bottle, and 10 mL of a N,N'-dimethylformamide / methanol mixed solvent (solvent volume ratio: 1 / 1) was added with a dropper. The mixture was reacted at 50°C for 72 h. When the solution became turbid, heating was stopped. After the temperature dropped to room temperature, the solution was centrifuged (at a speed of 10,000 rpm) to obtain a solid. The obtained solid was ultrasonically washed with methanol and then centrifuged. This operation was repeated three times to obtain a washed solid.
[0059] The solvent was exchanged with methanol (20 mL per reaction) for 6 hours with stirring, followed by centrifugation to obtain a solid. This solvent exchange procedure was repeated five times. The methanol-exchanged solid was then vacuum-dried at 120°C for 12 hours to obtain an imidazolyl metal-organic framework nanopowder (abbreviated as Zn(CN-IM)2) with a yield of 78% and a purity of 80%.
[0060] The obtained powder material was dispersed in 5 mL of methanol to obtain a dispersion with a concentration of 20 mg / mL, and 2 drops of the dispersion (0.1 mL) were dripped onto a carrier aluminum sheet using a 5 mL dropper and air-dried at room temperature; then vacuum-dried at 120° C. for 12 h to obtain an imidazole-based metal organic framework membrane element (i.e., an enricher), such as Figure 20 By calculating the mass of the carrier and the membrane element, the mass of the imidazolyl metal organic framework material in the membrane element was calculated to be 30 mg based on the mass difference.
[0061] The structure of the material was determined by X-ray diffraction. The powder X-ray diffraction pattern of Zn(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the material has obvious diffraction peaks at 7.3° and 12.5°. After comparison, it was found that these diffraction peaks are consistent with ZIF-8 generated by the classic reaction of 2-methylimidazole and zinc, indicating that the material is isostructural with ZIF-8. The specific structure is as follows Figure 1 shown.
[0062] Nicolet IS50 infrared spectrometer and KBr tablet were used to measure whether the reaction occurred. The infrared spectrum of Zn(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the material is 420cm -1 The vibration absorption peak of Zn-N appears at , indicating that the coordination reaction between the ligand and the metal occurs smoothly.
[0063] Thermogravimetric analysis was performed using a Mettler Toledo, TGA / DSC 3+ thermogravimetric analyzer. The thermogravimetric curve was used to determine the thermal stability of the material and verify the purity of the material. The thermogravimetric curve of Zn(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 4 As shown. Figure 4 It can be seen that Zn(CN-IM)2 does not lose weight before 100°C, indicating that there is no solvent residue in the material; it begins to lose weight after 230°C, indicating that the Zn(CN-IM)2 prepared by the present invention has good thermal stability.
[0064] The powder and membrane element prepared in this example were characterized by scanning electron microscopy. Figure 5 As shown, the prepared Zn(CN-IM)2 particles have a size of 50 to 200 nm; Figure 5 As shown, there are no obvious cracks on the surface of the prepared Zn(CN-IM)2 membrane, indicating that the prepared membrane element has good continuity, and the thickness of the film is 60μm.
[0065] Test Case
[0066] The adsorption curves of carbon dioxide and nitrogen of the Zn(CN-IM)2 material prepared in Example 1 were tested at 298K using Autosorb iQ2 adsorptometer and Quantachrome automatic adsorption instrument. The test results are as follows: Figure 6 As shown in the figure, the solid data are carbon dioxide adsorption data, and the hollow data are nitrogen adsorption data. Figure 6 It can be seen that the adsorption capacity of Zn(CN-IM)2 material for carbon dioxide is 36.2 cm 3 / g, and the adsorption capacity of nitrogen is 1.6cm 3 / g; It shows that the Zn(CN-IM)2 prepared by the present invention has a low adsorption capacity for nitrogen and a high adsorption capacity for carbon dioxide, and can achieve selective adsorption of carbon dioxide in a carbon dioxide-nitrogen mixed system. Figure 6 It can be seen that the adsorption selectivity of Zn(CN-IM)2 material for carbon dioxide in a carbon dioxide-nitrogen mixed system is 178, indicating that the Zn(CN-IM)2 prepared by the present invention has high selective adsorption performance for carbon dioxide in a carbon dioxide-nitrogen mixed system.
[0067] Use as Figure 21 The dynamic adsorption device shown was used to test the enrichment of carbon dioxide at low concentrations on the membrane element prepared in Example 1. The test gas composition was carbon dioxide and nitrogen, with carbon dioxide concentrations of 1 ppm, 10 ppm, and 100 ppm, respectively. The test results are shown in Table 2. The carbon dioxide enrichment capacity of the prepared Zn(CN-IM)2 membrane element was 0.03 cm 3 / g; through the formula PF=C i / C f The calculated enrichment factor is 748, indicating that Zn(CN-IM)2 material has a high capacity and high selectivity enrichment effect on carbon dioxide.
[0068] Table 2
[0069]
[0070]
[0071] Example 2
[0072] Under normal pressure and stirring, cobalt acetate (Co(CH3COO)2, 88.5 mg, 0.5 mmol) and 4,5-dicyanoimidazole (C5H2N4, 113.3 mg, 0.96 mmol) were added to a glass bottle. 10 mL of a mixed solvent of N,N'-dimethylformamide and acetonitrile (volume ratio: 1 / 1) was added using a dropper. The reaction was carried out at 50°C for 72 h. When the solution became turbid, heating was stopped. After the temperature dropped to room temperature, the solution was centrifuged (at 10,000 rpm) to obtain an initial solid. The obtained solid was ultrasonically washed with acetonitrile and then centrifuged. This operation was repeated three times to obtain a washed solid. The solvent was exchanged with acetonitrile, using 20 mL of acetonitrile each time. The exchange was carried out under stirring for 6 h, followed by centrifugation to obtain a solid. This solvent exchange step was repeated five times. The solid after acetonitrile exchange was vacuum dried at 120° C. for 12 h to obtain an imidazole-based metal organic framework nanopowder material (abbreviated as Co(CN-IM) 2, with a yield of 70% and a purity of 80%).
[0073] The obtained powder material was dispersed in 5 mL of acetonitrile to obtain a dispersion with a concentration of 20 mg / mL, and 2 drops of the dispersion (0.1 mL) were spin-coated on a silicon wafer using a 5 mL dropper (rotation speed 500 rpm), and dried at room temperature; then vacuum dried at 120 ° C for 12 h to obtain an imidazole-based metal organic framework membrane element ( Figure 20 By calculating the mass of the carrier silicon wafer and the membrane element, the mass of the imidazolyl metal organic framework material in the membrane element was calculated to be 40 mg based on the mass difference.
[0074] The structure of the material was determined by X-ray diffraction. The powder X-ray diffraction pattern of Co(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 9 As shown. Figure 9 It can be seen that the material has obvious diffraction peaks at 7.3° and 12.5°. After comparison, it was found that these diffraction peaks are consistent with ZIF-7 generated by the reaction of classic 2-methylimidazole and zinc, indicating that the material is isostructural with ZIF-7. The specific structure is as follows Figure 1 shown.
[0075] Nicolet IS50 infrared spectrometer and KBr pellet were used to determine whether the reaction occurred. The infrared spectrum of Co(CN-IM)2 prepared in this example is shown in FIG. Figure 10 As shown. Figure 10 It can be seen that the material is 414cm -1 The vibration absorption peak of Co-N appears at , indicating that the coordination reaction between the ligand and the metal occurs smoothly.
[0076] The thermal stability of the material and the purity of the material were determined by the thermogravimetric curve of the Mettler Toledo TGA / DSC 3+ thermogravimetric analyzer. Figure 11 As shown. Figure 11 It can be seen that the Co(CN-IM)2 material did not lose weight before 100°C, indicating that there was no solvent residue in the material; it began to lose weight after 245°C, indicating that the Co(CN-IM)2 prepared by the present invention has good thermal stability.
[0077] The powder and membrane element prepared in this example were characterized by scanning electron microscopy. Figure 12 As shown in , the prepared powder particle size is 50 to 200 nm; Figure 12 As shown, there are no obvious cracks on the surface of the prepared Co(CN-IM)2 membrane, indicating that the prepared membrane element has good continuity, and the thickness of the film is 80μm.
[0078] Test Case
[0079] The adsorption curves of the Co(CN-IM)2 material prepared in Example 1 for carbon dioxide and nitrogen were tested at 298K using Autosorb iQ2 adsorptometer and Quantachrome automatic adsorption instrument. The test results are shown in Figure 2. Figure 13 As shown in the figure, where the solid area is the carbon dioxide adsorption point and the hollow area is the nitrogen adsorption point. Figure 13 It can be seen that the adsorption capacity of Co(CN-IM)2 material for carbon dioxide is 29.2 cm 3 / g, and the adsorption capacity of nitrogen is 1.1cm 3 / g; It shows that the Co(CN-IM)2 prepared by the present invention has a low adsorption capacity for nitrogen and a high adsorption capacity for carbon dioxide, and can achieve selective adsorption of carbon dioxide in a carbon dioxide-nitrogen mixed system. Figure 13It can be seen that the adsorption selectivity of Co(CN-IM)2 material for carbon dioxide in a carbon dioxide-nitrogen mixed system is 195, indicating that the Co(CN-IM)2 prepared by the present invention has high selective adsorption performance for carbon dioxide in a carbon dioxide-nitrogen mixed system.
[0080] Use as Figure 21 The dynamic adsorption device shown was used to test the enrichment of carbon dioxide at low concentrations on the membrane element prepared in Example 2. The test gas composition was carbon dioxide and nitrogen, with carbon dioxide concentrations of 1 ppm, 10 ppm, and 100 ppm, respectively. The test results are shown in Table 3. The carbon dioxide enrichment capacity of the prepared Co(CN-IM)2 membrane element was 0.028 cm 3 / g; through the formula PF=C i / C f The calculated enrichment factor is 1480, indicating that the Co(CN-IM)2 material has a high capacity and high selectivity enrichment effect on carbon dioxide.
[0081] Table 3
[0082] [CO2 initial concentration] <![CDATA[富集后脱附CO2浓度]]> Figure 21 Figure 21 Figure 21 1480.6 Figure 21 Figure 21 182.7 Figure 21 Figure 21 16.5
[0083] Example 3
[0084] (1) Under normal pressure and stirring, zinc acetate (Zn(CH3COO)2, 45.8 mg, 0.25 mmol), cobalt acetate (Co(CH3COO)2, 44.3 mg, 0.25 mmol), and 4,5-dicyanoimidazole (C5H2N4, 113.3 mg, 0.96 mmol) were added to a glass bottle, and 10 mL of N,N'-dimethylformamide / methanol mixed solvent (solvent volume ratio: 1 / 1) was added with a dropper. The reaction was carried out at 50°C for 72 h. When the solution became turbid, heating was stopped. After the temperature dropped to room temperature, the solution was centrifuged (at a speed of 10,000 rpm) to obtain a solid. The obtained solid was ultrasonically washed with methanol and then centrifuged. This operation was repeated three times to obtain a washed solid. The solvent was exchanged with methanol, with the amount of methanol used each time being 20 mL. The exchange was carried out under stirring for 6 h, and then centrifuged to obtain a solid. This solvent exchange step was repeated five times. The solid after methanol exchange was vacuum dried at 120° C. for 12 h to obtain an imidazole-based metal organic framework nanopowder material (abbreviated as Zn / Co(CN-IM) 2, with a yield of 75% and a purity of 80%).
[0085] The resulting powder material was dispersed in 5 mL of methanol to obtain a dispersion with a concentration of 20 mg / mL. Two drops of the dispersion (0.1 mL) were then dripped onto a plexiglass sheet using a 5 mL dropper and allowed to air dry at room temperature. The membrane element was then vacuum-dried at 120°C for 12 hours to obtain an imidazolyl metal-organic framework (IMF) membrane element. The mass of the carrier silicon wafer and the membrane element was calculated, and the difference in mass revealed that the mass of the IMF material in the membrane element was 15 mg.
[0086] The structure of the material was determined by X-ray diffraction. The powder X-ray diffraction pattern of Zn / Co(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 21 As shown. Figure 21 It can be seen that the material has obvious diffraction peaks at 7.3° and 12.5°. After comparison, it was found that these diffraction peaks are consistent with the crystals generated by the reaction of 4,5-dicyanoimidazole and zinc, indicating that the material is isostructural with Zn(CN-IM)2.
[0087] The reaction was determined by using a Nicolet IS50 infrared spectrometer and KBr pellets. The infrared spectrum of Zn / Co(CN-IM)2 prepared in this example is shown in FIG. Figure 21 As shown. Figure 21 It can be seen that the material is at 421cm -1 、412cm -1 The vibration absorption peaks of Zn-N and Co-N appear at the positions respectively, indicating that the coordination reaction between the ligand and the metal occurs smoothly.
[0088] Thermogravimetric analysis was performed using a Mettler Toledo, TGA / DSC 3+ thermogravimetric analyzer. The thermogravimetric curve was used to determine the thermal stability of the material and verify the purity of the material. The thermogravimetric curve of Zn / Co(CN-IM)2 prepared in this embodiment is shown in FIG. Figure 21 As shown. Figure 21 It can be seen that Zn / Co(CN-IM)2 does not lose weight before 100°C, indicating that there is no solvent residue in the material; it begins to lose weight after 240°C, indicating that the Zn / Co(CN-IM)2 prepared by the present invention has good thermal stability.
[0089] The powder and membrane element prepared in this example were characterized by scanning electron microscopy. Figure 21 As shown in Figure 2, the particle size of the prepared powder is 50 to 200 nm; Figure 21 As shown, there are no obvious cracks on the surface of the prepared Zn / Co(CN-IM)2 film, indicating that the prepared membrane element has good continuity, and the thickness of the film is 30μm.
[0090] Test Case
[0091] The adsorption curves of Zn / Co(CN-IM)2 material prepared in Example 3 for carbon dioxide and nitrogen were tested at 298K using Autosorb iQ2 adsorptometer and Quantachrome automatic adsorption instrument. The test results are shown in Figure 2. Figure 21 As shown in the figure, where the solid area is the carbon dioxide adsorption point and the hollow area is the nitrogen adsorption point. Figure 21 It can be seen that the adsorption capacity of Zn / Co(CN-IM)2 material for carbon dioxide is 35.8 cm 3 / g, and the adsorption capacity of nitrogen is 1.3cm 3 / g; It shows that the Zn / Co(CN-IM)2 prepared by the present invention has a low adsorption capacity for nitrogen and a high adsorption capacity for carbon dioxide, and can achieve selective adsorption of carbon dioxide in a carbon dioxide-nitrogen mixed system. Figure 21 It can be seen that the adsorption selectivity of Zn / Co(CN-IM)2 material for carbon dioxide in a carbon dioxide-nitrogen mixed system is 192, indicating that the Zn / Co(CN-IM)2 prepared by the present invention has high selective adsorption performance for carbon dioxide in a carbon dioxide-nitrogen mixed system.
[0092] Use as Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 Figure 21 The dynamic adsorption device shown was used to test the enrichment of carbon dioxide at low concentrations on the membrane element prepared in Example 3. The test gas composition was carbon dioxide and nitrogen, with carbon dioxide concentrations of 1 ppm, 10 ppm, and 100 ppm, respectively. The test results are shown in Table 4. The carbon dioxide enrichment capacity of the prepared Zn / Co(CN-IM)2 membrane element was 0.029 cm 3 / g; through the formula PF=C i / C f The calculated enrichment factor is 950, indicating that the Zn / Co(CN-IM)2 material has a high capacity and high selectivity enrichment effect on carbon dioxide.
[0093] Table 4
[0094]
[0095]
[0096] The elemental composition and content of the powder materials in Examples 1-3 were determined by inductively coupled plasma emission spectroscopy and elemental analyzer, and the results are shown in Table 1.
[0097] Table 1
[0098]
Claims
1. An application of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide, characterized in that: The imidazole-based metal organic framework nanomaterial comprises a metal salt and an organic ligand; wherein the organic ligand is 4,5-dicyanoimidazole.
2. The use of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide according to claim 1, characterized in that: The metal ions in the metal salt include zinc ions or cobalt ions.
3. The use of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide according to claim 2, characterized in that: The molar ratio of the metal ion to the organic ligand is 1:(1.5-6).
4. The use of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide according to claim 1, characterized in that: The nanomaterial has a crystalline structure and a grain size of 50-200 nm.
5. The use of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide according to claim 1, characterized in that: The preparation method of the imidazole-based metal organic framework nanomaterial comprises: mixing a metal salt, an organic ligand and an organic solvent under normal pressure and stirring, performing a coordination reaction at a certain temperature, and then centrifuging, washing and drying in sequence to obtain the imidazole-based metal organic framework nanomaterial.
6. The use of an imidazole-based metal organic framework nanomaterial in selective adsorption of carbon dioxide according to claim 5, characterized in that: The coordination reaction temperature is 25-60° C., and the time is 24-96 h.
7. Use of the imidazole-based metal organic framework nanomaterial for selectively adsorbing carbon dioxide according to any one of claims 1 to 6 in a low-concentration carbon dioxide enricher, characterized in that: The preparation method of the low-concentration carbon dioxide enricher is as follows: The prepared imidazole-based metal organic framework nanomaterial is dispersed in an anhydrous organic solvent, and then the obtained dispersion is deposited on a component to form a thin film. After removing the solvent, the concentrator is obtained.
8. The use of the imidazole-based metal organic framework nanomaterial for selectively adsorbing carbon dioxide in a low-concentration carbon dioxide concentrator according to claim 7, characterized in that: The concentration of the dispersion is 5-20 mg / mL.
9. The use of the imidazole-based metal organic framework nanomaterial for selectively adsorbing carbon dioxide in a low-concentration carbon dioxide concentrator according to claim 8, characterized in that: The thickness of the film is ≤60 μm.