Metal organic framework material for adsorbing carbon dioxide and preparation method thereof

Abstract

The invention provides a Ca-MOF metal organic framework material, a preparation method thereof and application of the Ca-MOF metal organic framework material in carbon dioxide adsorption. A novel porous material is formed by taking Ca < 2 + > as a coordination metal and benzo-[1, 2-b: 3, 4-b ': 5, 6-b'] trithiophene-2, 5, 8-tricarboxylic acid as an organic ligand and carrying out solvothermal reaction in a mixed solvent composed of an organic solvent and water, the material is a metal organic framework material with a net structure, and the material has a cage-shaped structure, so that the porous material is a porous material. Meanwhile, the compound has a multi-core calcium cluster element and a large number of open metal sites. The open metal site is a Lewis acid site which polarizes gas molecules such as carbon dioxide and the like, and the interaction between the gas such as carbon dioxide and the metal organic framework material is enhanced, so that the capture capacity of CO2 is improved, and the high adsorption capacity of CO2 is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of metal organic framework materials, and in particular to a Ca-MOF metal organic framework material, a preparation method thereof, and an application thereof in adsorbing carbon dioxide. Background Art

[0002] Since the Industrial Revolution, the use of fossil fuels has grown dramatically to meet the growing global energy demand and technological development. The reliance of many industrial activities on the combustion of fossil fuels has inevitably caused the concentration of carbon dioxide in the atmosphere to rise to unprecedented levels, leading to serious environmental disasters such as global warming and climate change. In order to solve these problems and the global energy crisis, it is urgent to develop strategies to reduce greenhouse gas emissions and reduce dependence on fossil fuels.

[0003] Metal-organic Frameworks (MOFs), as a crystalline porous material with a periodic network structure formed by metal ions or metal clusters and organic ligands containing coordinating atoms such as O, N, and S connected by coordination bonds, have attracted great attention from chemical researchers in recent years. MOFs materials have the advantages of ultra-high specific surface area, good chemical stability, diverse structures, and modifiable functions, and play a good role in capturing and separating carbon dioxide gas. Summary of the invention

[0004] The present invention aims to provide a Ca-MOF metal organic framework material and a preparation method thereof and application in the adsorption of carbon dioxide. The Ca-MOF metal organic framework material provided by the present invention has good adsorption capacity for carbon dioxide.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A Ca-MOF metal organic framework material, characterized in that the organic ligand of the metal organic framework material is benzo-[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid, and the coordination metal is Ca 2+ ; The Ca-MOF metal organic framework material has a cage-like structure.

[0007] Preferably, the Ca-MOF metal organic framework material has a tetra-nuclear calcium cluster structural unit.

[0008] The present invention provides a method for preparing the above-mentioned Ca-MOF metal organic framework material, comprising the following steps: mixing a soluble copper salt, a soluble indium salt, an organic ligand and a polar organic solvent to obtain a mixed solution; mixing the mixed solution with a low boiling point solvent, performing a solvothermal reaction, and obtaining the Ca-MOF metal organic framework material.

[0009] Preferably, the soluble calcium salt is one or more of calcium chloride, calcium nitrate, calcium acetate, calcium carbonate, calcium sulfate and calcium perchlorate.

[0010] The molar ratio of the soluble calcium salt to the organic ligand is 1-3:1-2.

[0011] Preferably, the polar organic solvent is an amide solvent, and the amide solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylformamide; the low boiling point solvent is one or more of water, acetonitrile, methanol and ethanol.

[0012] Preferably, the volume ratio of the polar organic solvent to the low boiling point solvent is 1-2 mL:20-400 μL.

[0013] Preferably, the temperature of the solvent thermal reaction is 100-120° C. and the time is 24-72 hours.

[0014] The present invention provides the use of the calcium-based metal organic framework material described in the above technical solution or the calcium-based metal organic framework material prepared by the preparation method described in the above technical solution in adsorbing carbon dioxide.

[0015] The present invention provides a Ca-MOF metal organic framework material, characterized in that the organic ligand of the Ca-MOF metal organic framework material is benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid, and the coordination metal is Ca 2+ The Ca-MOF metal organic framework material has a cage structure. 2+ As a coordination metal, benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid is used as an organic ligand. The material is a metal organic framework material with a three-dimensional network structure, and the material has a cage structure, and has a multi-core calcium cluster unit and a large number of open metal sites. These open metal sites can be regarded as Lewis acid sites to polarize gas molecules such as carbon dioxide, thereby strengthening the interaction between gases such as carbon dioxide and the MOFs material skeleton, and improving the CO 2 Capture and separation capabilities to achieve CO 2 The results of the embodiment show that the adsorption capacity of carbon dioxide by Ca-MOF metal organic framework material is 35cm at 273K and 1bar. 3 g -1 The adsorption capacity of carbon dioxide at 298K and 1bar is 67cm 3 g -1 .

[0016] The present invention provides a method for preparing the above-mentioned Ca-MOF metal organic framework material. The present invention is based on the theory of soft and hard acid and base, and adopts a "one-pot method" to synthesize the Ca-MOF metal organic framework material. 3 The solvothermal reaction of BTTC and calcium metal salt can enrich the types of structural elements, connection methods, skeleton structures and pore structures of MOFs materials. The obtained Ca-MOF has stable structural performance, multi-core calcium cluster structural elements and a large number of open metal sites, which ensures a sufficiently high carbon dioxide adsorption capacity. At the same time, the preparation method provided by the present invention is simple to operate, low in cost, and easy to realize industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the crystal structure of Ca-MOF;

[0018] Figure 2 Schematic diagram of the microscopic crystal structure of Ca-MOF;

[0019] Figure 3 PXRD characterization data of Ca-MOF and its solvent immersion;

[0020] Figure 4 is the 77K nitrogen adsorption curve of Ca-MOF;

[0021] Figure 5 This is the carbon dioxide adsorption curve of Ca-MOF. DETAILED DESCRIPTION

[0022] The present invention provides a Ca-MOF metal organic framework material, wherein the organic ligand of the Ca-MOF metal organic framework material is benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid;

[0023] The Ca-MOF metal organic framework material has a cage-like structure.

[0024] In the present invention, the Ca-MOF metal organic framework material has a tetra-nuclear calcium cluster structural unit.

[0025] In the present invention, the molar ratio of the soluble calcium salt to the organic ligand is 1-3:1-2.

[0026] In the present invention, the specific surface area of ​​the Ca-MOF metal organic framework material is 900 to 1000 m 2 / g, preferably 921m 2 / g; the actual pore volume is 0.3-0.5cm 3 / g, preferably 0.45cm 3 / g; the porosity is 50-70%, preferably 57.7%.

[0027] The present invention provides a method for preparing the above-mentioned Ca-MOF metal organic framework material, comprising the following steps:

[0028] mixing a soluble calcium salt, an organic ligand and a polar organic solvent to obtain a mixed solution;

[0029] The mixed solution is mixed with a low boiling point solvent to perform a solvothermal reaction to obtain a Ca-MOF metal organic framework material.

[0030] The present invention mixes a soluble calcium salt, an organic ligand and a polar organic solvent to obtain a mixed solution. In the present invention, the soluble calcium salt is preferably one or more of calcium chloride, calcium nitrate, calcium acetate, calcium carbonate, calcium sulfate and calcium perchlorate, and more preferably calcium chloride hydrate. In the present invention, the molar ratio of the soluble calcium salt to the organic ligand is preferably 1-3:1-3, and more preferably 1-2:1-2.

[0031] In the present invention, the polar organic solvent is preferably one or more of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylformamide, more preferably N,N-dimethylacetamide.

[0032] In the present invention, the volume ratio of the amount of the soluble calcium salt to the polar organic solvent is preferably 0.01-0.03 mmol:1-3 mL.

[0033] The present invention has no special requirements for the mixing method, and any mixing method well known to those skilled in the art may be used, such as stirring and mixing.

[0034] After obtaining the mixed solution, the present invention mixes the mixed solution with a low boiling point solvent, performs a solvothermal reaction, and obtains a Ca-MOF metal organic framework material. In the present invention, the boiling point solvent is preferably one or more of water, acetonitrile, methanol and ethanol, more preferably water. In the present invention, the volume ratio of the polar organic solvent to the low boiling point solvent is 1 to 3 mL: 20 to 500 μL. In the present invention, the role of the low boiling point solvent is to adjust the polarity of the mixed solution.

[0035] In the present invention, the temperature of the solvothermal reaction is preferably 100 to 120° C., more preferably 100 to 110° C., and the time is preferably 24 to 72 hours, more preferably 24 to 48 hours.

[0036] In the present invention, after the solvothermal reaction, the obtained solvothermal reaction product is preferably washed and dried. The present invention has no special requirements for the washing and drying methods, and washing and drying methods well known to those skilled in the art can be used.

[0037] The present invention provides application of the Ca-MOF metal organic framework material in adsorbing carbon dioxide.

[0038] In the present invention, before the Ca-MOF metal organic framework material adsorbs carbon dioxide, the present invention preferably activates the Ca-MOF metal organic framework material.

[0039] In the present invention, the activation method preferably comprises the following steps:

[0040] The Ca-MOF metal organic framework material is mixed with acetone to perform solvent exchange to obtain a pretreated Ca-MOF metal organic framework material;

[0041] The pretreated Ca-MOF metal organic framework material is subjected to degassing treatment to obtain an activated Ca-MOF metal organic framework material.

[0042] In the present invention, the solvent exchange time is 1 to 3 hours each time, and the number of times is preferably multiple times.

[0043] In the present invention, the degassing treatment is preferably carried out under vacuum conditions, the temperature of the degassing treatment is preferably 0 to 50° C., more preferably 30° C., and the time is preferably 8 to 12 h, more preferably 10 h.

[0044] The Ca-MOF metal organic framework material provided by the present invention, its preparation method and its application in the adsorption of carbon dioxide are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1

[0046] The organic ligand of the Ca-MOF metal organic framework material is benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid;

[0047] The preparation method of the above-mentioned Ca-MOF metal organic framework material is as follows:

[0048] Weigh 6 mg of copper chloride and 5 mg of organic ligand benzo[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid into a 20 mL glass bottle, and dissolve them in 1 mL of DMA. Ultrasonicate for 20 minutes to mix them thoroughly, then add 0.5 mL of water, cover and seal, and heat in a 105 °C oven for 24 hours. Take out and cool to obtain colorless polyhedrons, which are collected, washed with DMA and dried.

[0049] The crystal diagram of the obtained Ca-MOF is shown in Figure 1 The crystal structure diagram of Ca-MOF is shown in Figure 2The PXRD characterization data of the obtained Ca-MOF are shown in Figure 3 As shown. It can be seen that the Ca-MOF material provided by the present invention has a cage structure and a tetranuclear calcium cluster structural unit, and therefore has a large number of open metal sites, ensuring a sufficiently high carbon dioxide adsorption capacity. The reasonable structural design enables the Ca-MOF material to achieve good stability and relatively high carbon dioxide adsorption performance.

[0050] Test Example 1

[0051] In order to test the chemical stability of the material, it was immersed in Acetone solution. After immersion for 3 days, the PXRD characterization data of Ca-MOF were as follows: Figure 3 As shown in the PXRD spectrum, it can be seen that after being immersed in organic solvents, Ca-MOF still has good stability.

[0052] Test Example 2

[0053] First, the Ca-MOF was activated, and the free guest molecules in the pores were exchanged with a low-boiling-point acetone solvent. The solvent exchange method was used for multiple exchanges in acetone, each time at least 3 hours apart. The sample was degassed for 10 hours under vacuum conditions at 30°C. After the fully activated sample was obtained, further performance testing was performed. In order to test the specific surface area of ​​the Ca-MOF material, a 77K nitrogen isothermal adsorption test was performed, and the results are shown in Figure 4 It can be seen that the nitrogen adsorption curve is a typical type I curve, and the BET specific surface area is 921m 2 / g.

[0054] Test Example 3

[0055] The carbon dioxide adsorption capacity of Ca-MOF was tested at 273K and 298K and 1 bar. The obtained carbon dioxide adsorption curves are shown in the figure. Figure 5 As shown. It can be seen that the carbon dioxide adsorption capacity of Ca-MOF at 273K and 1 bar is 35cm 3 g -1 , the carbon dioxide adsorption capacity is 16cm at 298K and 1bar. 3 g -1 .

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A Ca-MOF metal organic framework material, characterized in that the organic ligand of the metal organic framework material is benzo-[1,2-b:3,4-b':5,6-b']terthiophene-2,5,8-tricarboxylic acid, and the coordination metal is Ca 2+ ; The Ca-MOF metal organic framework material has a cage-like structure.

2. The Ca-MOF metal organic framework material according to claim 1, characterized in that The Ca-MOF metal organic framework material has a tetra-nuclear copper cluster structural unit.

3. The method for preparing the Ca-MOF metal organic framework material according to any one of claims 1 or 2, comprising the following steps: mixing a soluble calcium salt, an organic ligand and a polar organic solvent to obtain a mixed solution; The mixed solution is mixed with a low boiling point solvent to perform a solvothermal reaction to obtain a Ca-MOF metal organic framework material.

4. The preparation method according to claim 3, characterized in that: The soluble calcium salt is one or more of calcium chloride, calcium nitrate, calcium acetate, calcium carbonate, calcium sulfate and calcium perchlorate.

5. The preparation method according to claim 3 or 4, characterized in that: The molar ratio of the soluble calcium salt to the organic ligand is 1-3:1-2.

6. The preparation method according to claim 3, characterized in that: The polar organic solvent is an amide solvent, and the amide solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide and N-methylformamide; The low boiling point solvent is one or more of water, acetonitrile, methanol and ethanol.

7. The preparation method according to claim 3 or 6, characterized in that: The volume ratio of the polar organic solvent to the low boiling point solvent is 1-2 mL: 20-400 μL.

8. The preparation method according to claim 3, characterized in that: The temperature of the solvent thermal reaction is 100-120° C. and the time is 24-72 hours.

9. Use of the Ca-MOF metal organic framework material according to any one of claims 1 to 3 or the Ca-MOF metal organic framework material prepared by the preparation method according to any one of claims 4 to 8 in the adsorption of carbon dioxide.

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