Nano zeolite imidazole framework material and CO2Auxiliary preparation method and application
阅读说明：本技术 纳米沸石咪唑骨架材料和co2辅助制备方法及应用 (Nano zeolite imidazole framework material and CO2Auxiliary preparation method and application ) 是由 詹国武 曾小丽 陈彬 肖静冉 周树锋 于 2020-07-02 设计创作，主要内容包括：本发明公开了纳米沸石咪唑骨架材料和CO<Sub>2</Sub>辅助制备方法及应用。通过在ZIFs的合成过程中引入CO<Sub>2</Sub>气体作为调节介质,利用CO<Sub>2</Sub>气体的通入与撤除处理,可逆地破坏金属离子与有机配体之间的配位键,使ZIFs在溶解再结晶的过程中快速发生结构转变,最终制备nano ZIFs。该制备方法耗时短、操作简便、重复性好、合成工艺经济环保,制备的nano ZIFs具有颗粒尺寸小、比表面积大、结晶度高、热稳定性好、纯度高等优点。之外,nano ZIFs还具有良好的有机染料光降解催化活性。(The invention discloses a nanometer zeolite imidazole framework material and CO 2 An auxiliary preparation method and application. By introducing CO during the synthesis of ZIFs 2 Using gas as conditioning medium, using CO 2 And (3) introducing and removing the gas to reversibly destroy the coordination bond between the metal ions and the organic ligand, so that the structure of the ZIFs is rapidly changed in the dissolving and recrystallization processes, and finally the nano ZIFs are prepared. The preparation method has the advantages of short time consumption, simple and convenient operation, good repeatability and economic and environment-friendly synthesis process, and the prepared nano ZIFs have the advantages of small particle size, large specific surface area, high crystallinity, good thermal stability, high purity and the like. Besides, nano ZIFs also have good catalytic activity for photodegradation of organic dyes.)
1.CO2The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: introduction of CO during synthesis of ZIFs2Gas, using CO2Introducing and removing gas to make ZIFs generate structural transformation in the process of dissolving and recrystallizing, and preparing to obtain nano zeolite imidazole framework materials, which are marked as nano ZIFs;
the CO is2The gas introducing and removing treatment comprises the following steps:
after the metal salt and the organic ligand are mixed to generate precipitation, introducing CO with the pressure of 1-50 bar2Gas is discharged for 10-120 min, and then CO is removed2And (4) stirring and reacting for 10-120 min.
2. CO according to claim 12Auxiliary preparation of nano zeoliteThe method for preparing the azole framework material is characterized by comprising the following steps: the method comprises the following steps:
(1) dissolving metal salt in an alcohol solvent, and stirring until the metal salt is completely dissolved to obtain a solution A; dissolving an organic ligand in an alcohol solvent, adding an alkali liquor, and stirring until the organic ligand is completely dissolved to obtain a solution B; mixing the solution A and the solution B to obtain turbid liquid generating white solid precipitate;
(2) introducing CO into the turbid liquid2Gas, when the turbid liquid is converted into a clear solution; then CO is removed2Stirring the gas to ensure that the clear solution gradually generates a milky solid product; and centrifuging to recover a solid product, and cleaning and drying to obtain nano ZIFs.
3. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: the metal salt is one or more of anhydrous zinc acetate, zinc acetate dihydrate, anhydrous zinc nitrate, zinc nitrate hexahydrate, anhydrous zinc sulfate, zinc sulfate heptahydrate, anhydrous cobalt acetate, cobalt acetate tetrahydrate, anhydrous cobalt nitrate, cobalt nitrate hexahydrate, anhydrous cobalt sulfate and cobalt sulfate heptahydrate.
4. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: the alcohol solvent is one or more of methanol, ethanol, ethylene glycol, n-propanol, isopropanol and propylene glycol.
5. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: the organic ligand is one or more of 1-methylimidazole, 2-methylimidazole, 1, 2-methylimidazole, 2, 4-methylimidazole, 2-formylimidazole, 1-ethylimidazole and 2-ethylimidazole.
6. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: the alkali liquor is ethylenediamine, triethylamine, propylamine, n-butylamine,One or more of tert-butylamine, ammonia water, sodium hydroxide and potassium hydroxide.
7. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: the molar ratio of the metal salt to the organic ligand is 1: 1-8, and the molar ratio of the alkali liquor to the organic ligand is 1: 1-5.
8. CO according to claim 22The method for preparing the nano zeolite imidazole framework material in an auxiliary way is characterized by comprising the following steps: and washing the centrifugally recovered solid product with ethanol for 3-5 times, and drying in an oven at 55-65 ℃ for 12-14 hours to obtain nano ZIFs.
9. A nano zeolitic imidazolate framework material prepared according to the method of any of claims 1 to 8, characterized in that: the ZIFs particles are nano-sized, and the BET specific surface area of the ZIFs particles is 1180-1190 m2(ii)/g, pore diameter is not more than 2 nm.
10. Use of the nano zeolitic imidazolate framework material of claim 9 for the catalysis of the photodegradation of organic dyes.
Technical Field
The invention belongs to the technical field of nano material preparation, and particularly relates to a nano zeolite imidazole framework material and CO2An auxiliary preparation method and application.
Background
Zeolitic Imidazolate Frameworks (ZIFs) are built up of four-coordinated metal ions (e.g. Zn)2+Or Co2+) And an organic imidazole compound to form a metal-organic framework having a zeolite-like topology. Compared with most Metal Organic Frameworks (MOFs), ZIFs have higher physical and chemical stability and higher specific surface area. Therefore, ZIFs have become promising materials in various industries, including gas storage, membrane separation, catalysis, and biomedicine.
Similar to inorganic nanomaterials, the particle size and morphology of ZIFs play a key role in physicochemical properties and application performance. Therefore, many methods such as changing the concentration of the precursor solution, the type of solvent, the synthesis temperature, adding capping agents or lye additives, etc., have been used to adjust the particle size and morphology of the ZIFs particles. For example, Cravilon et al (Chemistry of materials,2011,23(8), 2130-. In addition, various surfactants and polymers have been used as structure directing agents to adjust the particle size and morphology of ZIFs. For example, Hu et al (ChemCatchem,2019,11(14),3212-3219) prepared ZIFs with different morphologies, such as solid spheres, hollow spheres, etc., using different surfactants as templates. However, optimizing various synthesis parameters during experimentation tends to be time consuming, expensive, and inefficient. In addition, in some cases, the addition of auxiliary chemicals to adjust the morphology and particle size of ZIFs particles may cause problems such as low purity or poor crystallinity, and therefore, it is important to develop a simpler and more direct method to precisely control the size and morphology of ZIFs crystals.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides nano zeolite imidazoleFramework material and CO2The auxiliary preparation method and the application solve the problems in the background technology.
One of the technical schemes adopted by the invention for solving the technical problems is as follows: providing a CO2The method for preparing nanometer zeolite imidazole framework material in an auxiliary way introduces CO in the synthesis process of ZIFs2Gas, using CO2Introducing and removing gas to make ZIFs generate structural transformation in the process of dissolving and recrystallizing, and preparing to obtain nano zeolite imidazole framework materials, which are marked as nano ZIFs;
the CO is2The gas introducing and removing treatment comprises the following steps:
after the metal salt and the organic ligand are mixed to generate precipitation, introducing CO with the pressure of 1-50 bar2Gas is discharged for 10-120 min, and then CO is removed2And (4) stirring and reacting for 10-120 min.
In a preferred embodiment of the present invention, the method comprises the following steps:
(1) dissolving metal salt in an alcohol solvent, and stirring until the metal salt is completely dissolved to obtain a solution A; dissolving an organic ligand in an alcohol solvent, adding an alkali liquor, and stirring until the organic ligand is completely dissolved to obtain a solution B; mixing the solution A and the solution B to obtain turbid liquid generating white solid precipitate;
(2) introducing CO into the turbid liquid2Gas, when the turbid liquid is converted into a clear solution; then CO is removed2Stirring the gas to ensure that the clear solution gradually generates a milky solid product; centrifugally recycling the solid product, cleaning and drying to obtain the NanoZIFs.
In a preferred embodiment of the present invention, the metal salt is one or more of anhydrous zinc acetate, zinc acetate dihydrate, anhydrous zinc nitrate, zinc nitrate hexahydrate, anhydrous zinc sulfate, zinc sulfate heptahydrate, anhydrous cobalt acetate, cobalt acetate tetrahydrate, anhydrous cobalt nitrate, cobalt nitrate hexahydrate, anhydrous cobalt sulfate, and cobalt sulfate heptahydrate.
In a preferred embodiment of the present invention, the alcohol solvent is one or more of methanol, ethanol, ethylene glycol, n-propanol, isopropanol, and propylene glycol.
In a preferred embodiment of the present invention, the organic ligand is one or more of 1-methylimidazole, 2-methylimidazole, 1, 2-methylimidazole, 2, 4-methylimidazole, 2-formylimidazole, 1-ethylimidazole and 2-ethylimidazole.
In a preferred embodiment of the present invention, the alkali solution is one or more of ethylenediamine, triethylamine, propylamine, n-butylamine, tert-butylamine, ammonia water, sodium hydroxide and potassium hydroxide.
In a preferred embodiment of the present invention, the molar ratio of the metal salt to the organic ligand is 1: 1-8, and the molar ratio of the alkali solution to the organic ligand is 1: 1-5.
In a preferred embodiment of the invention, the centrifugally recovered solid product is washed with ethanol for 3-5 times, and dried in an oven at 55-65 ℃ for 12-14 hours to obtain nano ZIFs.
The second technical scheme adopted by the invention for solving the technical problems is as follows: the nanometer zeolite imidazole framework material prepared by the method is nanometer ZIFs particles, and the BET specific surface area of the nanometer zeolite imidazole framework material is 1180-1190 m2(ii)/g, pore diameter is not more than 2 nm.
The third technical scheme adopted by the invention for solving the technical problems is as follows: provides the application of the nano zeolite imidazole framework material in catalyzing the photodegradation of organic dyes.
Compared with the background technology, the technical scheme has the following advantages:
1. the invention utilizes CO2The nucleation and growth of gas-mediated crystals reversibly destroy coordination bonds between metal ions and organic ligands, so that the ZIFs are rapidly subjected to structural transformation in the process of dissolution and recrystallization, and nano ZIFs are finally prepared;
2. the preparation method has the advantages of short time consumption, simple and convenient operation, good repeatability and economic and environment-friendly synthesis process;
3. the nano ZIFs prepared by the method has the advantages of small particle size, large specific surface area, high crystallinity, good thermal stability, high purity and the like;
4. the nano ZIFs prepared by the method has good catalytic activity for photodegradation of organic dyes.
Drawings
FIG. 1 is a scanning electron micrograph of nano ZIFs prepared in example 1, with a scale of 200 nm.
FIG. 2 is a scanning electron micrograph of nano ZIFs prepared in example 3, with a 2 μm scale in the middle.
FIG. 3 is a plot of the nitrogen physisorption and desorption isotherms of the nano ZIFs prepared in example 4 (the inset is the pore size distribution plot).
Detailed Description