Method for preparing high-content transition metal doped imidazole zeolite framework

Abstract

The invention relates to the technical field of imidazole zeolite frameworks, and discloses a method for preparing a high-content transition metal doped imidazole zeolite framework, which comprises the following steps: S1, dissolving zinc nitrate and another one or more soluble metal salts in a solvent to obtain a metal salt solution 1; s2, dissolving 2-methylimidazole and organic amine in a solvent to obtain a ligand solution 2; s3, mixing and stirring the solution 1 and the solution 2 at room temperature, and reacting for a period of time; s4, after a certain precipitate is formed, a product is sequentially subjected to centrifugal separation, washing, vacuum drying and the like, and the transition metal doped zeolite imidazole framework nano material is obtained. The method has the characteristics of simplicity, controllability, mild reaction conditions, high yield, high transition metal doping amount, good repeatability, strong universality and the like, and fills the blank of a high-content transition metal doped zeolite imidazole framework synthesis technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of imidazole zeolite frameworks, and particularly relates to a method for preparing imidazole zeolite frameworks doped with a high content of transition metals. Background Art

[0002] Zeolite imidazole frameworks are a class of ordered porous materials formed by the self-assembly of metal ions and imidazole ligands, with characteristics such as high specific surface area, highly tunable pore structure, and abundant active sites. In recent years, zeolite imidazole framework materials doped with transition metals have shown great application potential in the fields of catalysis, gas adsorption and separation, energy storage and conversion, etc. The introduction of transition metals (such as Fe, Co, Ni, Cu, Ru, etc.) can significantly change the electronic structure, catalytic activity, and selectivity of zeolite imidazole frameworks, thereby expanding their scope of functional applications. For example, zeolite imidazole frameworks doped with transition metals exhibit excellent catalytic performance in reactions such as electrocatalytic water splitting, carbon dioxide reduction, and organic pollutant degradation, and have become a research hotspot in the fields of green chemistry and sustainable energy.

[0003] Although zeolite imidazole framework materials doped with transition metals have broad application prospects, their preparation process still faces many challenges: 1. Uniformity of high-content doping: Achieving high-content transition metal doping in zeolite imidazole frameworks while maintaining the uniformity and stability of the crystal structure is a technical difficulty. The difference in the coordination ability between transition metal ions and ligands may lead to crystal structure defects or collapse, affecting the performance of the material; 2. Dispersion of doped metals: The dispersion of transition metals in zeolite imidazole frameworks directly affects their catalytic activity and selectivity; 3. Control of synthesis conditions: The synthesis of zeolite imidazole frameworks usually requires precise control of reaction temperature, solvent type, reaction time, etc. High-content transition metal doping may change the reaction kinetics and increase the synthesis difficulty. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a method for preparing imidazole zeolite frameworks doped with a high content of transition metals, which can overcome or at least partially solve the above problems.

[0005] The present invention is realized as follows. A method for preparing imidazole zeolite frameworks doped with a high content of transition metals includes the following steps:

[0006] S1: Add zinc nitrate and another or multiple soluble metal salts into an environmentally friendly solvent, and stir vigorously to dissolve to obtain metal salt solution 1;

[0007] S2: Add 2-methylimidazole and organic amine into an environmentally friendly solvent, and stir vigorously to dissolve to obtain ligand solution 2;

[0008] S3: Rapidly add Solution 1 to Solution 2, mix and stir at room temperature, and react for a period of time;

[0009] S4: After a certain amount of precipitation is formed, centrifuge the product to remove the solvent, and obtain the transition metal-doped zeolitic imidazolate framework nanomaterial after washing and vacuum drying, etc.

[0010] Preferably in the present invention, the soluble metal salt in S1 is selected from any one or more of MnSO4, Mn(CH3COO)2, MnCl2, FeCl2, FeSO4, FeCl3, Fe2(SO4)3, Fe(NO3)3, CoCl2, CoSO4, Co(NO3)2, NiCl2, NiSO4, Ni(NO3)2, Ni(CH3COO)2, CuCl2, CuSO4, Cu(CH3COO)2, Cu(NO3)2, RuCl3, RhCl3, IrCl3.

[0011] Preferably in the present invention, the molar ratio of zinc nitrate to the soluble metal salt in S1 is (1:2) - (40:1).

[0012] Preferably in the present invention, the environmentally friendly solvent in S1 and S2 is one or more of methanol, ethanol, and water.

[0013] Preferably in the present invention, the organic amine in S2 is selected from any one or more of n-propylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-hexylamine, n-pentylamine, di-n-butylamine, trimethylamine, triethylamine, and tripropylamine.

[0014] Preferably in the present invention, the molar ratio of 2-methylimidazole to the organic amine in S2 is (1:1) - (10:1).

[0015] Preferably in the present invention, the molar ratio of zinc nitrate to 2-methylimidazole in S3 is (1:16) - (1:2).

[0016] Preferably in the present invention, the washing solvent in S4 includes water, ethanol, acetone, etc., and wash three times repeatedly; the vacuum drying specifically means vacuum drying at 50 - 80 °C for 8 - 12 h.

[0017] Preferably, the highly transition-metal-doped imidazole zeolite framework in S4 is any one of Mn-ZIF-8, Fe-ZIF-8, Co-ZIF-8, Ni-ZIF-8, Cu-ZIF-8, Ru-ZIF-8, Rh-ZIF-8, Ir-ZIF-8, FeMn-ZIF-8, FeNi-ZIF-8, FeCo-ZIF-8, FeCu-ZIF-8, CoNi-ZIF-8, NiCu-ZIF-8, CoCu-ZIF-8, FeCoNi-ZIF-8, FeCoNiCu-ZIF-8, FeCoNiCuRu-ZIF-8.

[0018] Preferably, for its structural characterization, the powder X-ray diffraction pattern has sharp diffraction peaks and is the same as the crystal structure of ZIF-8 without doping other transition metals.

[0019] Preferably, for its pore size distribution and specific surface area analysis, the powder X-ray diffraction pattern has sharp diffraction peaks and is the same as the crystal structure of ZIF-8 without doping other transition metals.

[0020] Preferably, for its elemental analysis, the elemental mapping in energy-dispersive X-ray spectroscopy shows that the doped transition metals are uniformly dispersed in the imidazole zeolite framework, and the content of the doped transition metals can be as high as 13.7 wt%.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention can obtain a highly transition-metal-doped zeolite imidazole framework nanomaterial by an organic amine-assisted method; this method is simple and controllable, with mild reaction conditions, good repeatability, high yield, and can achieve mass production; the highly transition-metal-doped imidazole zeolite framework prepared by the present invention has good crystallinity, perfectly retains the crystal structure of the original ZIF-8, and has a high specific surface area; the synthesis conditions adopted by the present invention are mild, do not require the use of high temperature and high pressure, save energy, and reduce the preparation cost. Description of the Drawings

[0023] Figure 1 It is the process flow chart provided by the embodiment of the present invention;

[0024] Figure 2 It is the scanning electron micrograph of Ni-doped zeolite imidazole framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0025] Figure 3 It is the transmission electron micrograph of Ni-doped zeolite imidazole framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0026] Figure 4It is the element mapping diagram in the energy dispersive X-ray spectrum of Ni-doped zeolitic imidazolate framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0027] Figure 5 It is the powder X-ray diffraction pattern of Ni-doped zeolitic imidazolate framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0028] Figure 6 It is the N2 adsorption-desorption isotherm of Ni-doped zeolitic imidazolate framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0029] Figure 7 It is the micropore size distribution curve of Ni-doped zeolitic imidazolate framework Ni-ZIF-8 prepared in Example 1 of the present invention;

[0030] Figure 8 It is the element mapping diagram in the energy dispersive X-ray spectrum of Ru-doped zeolitic imidazolate framework Ru-ZIF-8 prepared in Example 2 of the present invention. Detailed implementation manners

[0031] To further understand the content, features and effects of the present invention, the following examples are given and described in detail with the accompanying drawings as follows.

[0032] The structure of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] As Figures 1 to 8 shown, a method for preparing a high-content transition metal-doped imidazole zeolite framework provided by an embodiment of the present invention includes the following steps:

[0034] S1: Add zinc nitrate and another or multiple soluble metal salts into an environmentally friendly solvent, and stir vigorously to dissolve to obtain a metal salt solution 1;

[0035] S2: Add 2-methylimidazole and organic amine into an environmentally friendly solvent, and stir vigorously to dissolve to obtain a ligand solution 2;

[0036] S3: Quickly add solution 1 into solution 2, mix and stir at room temperature, and react for a period of time;

[0037] S4: After a certain precipitate is formed, centrifuge and separate the product to remove the solvent, and then obtain the transition metal-doped zeolitic imidazolate framework nanomaterial through washing and vacuum drying, etc.

[0038] Preferably, in the present invention, the soluble metal salt in S1 is selected from any one or more of MnSO4, Mn(CH3COO)2, MnCl2, FeCl2, FeSO4, FeCl3, Fe2(SO4)3, Fe(NO3)3, CoCl2, CoSO4, Co(NO3)2, NiCl2, NiSO4, Ni(NO3)2, Ni(CH3COO)2, CuCl2, CuSO4, Cu(CH3COO)2, Cu(NO3)2, RuCl3, RhCl3, and IrCl3.

[0039] Preferably, in the present invention, the molar ratio of zinc nitrate to the soluble metal salt in S1 is (1:2) - (40:1).

[0040] Preferably, in the present invention, the environmentally friendly solvent in S1 and S2 is one or more of methanol, ethanol, and water.

[0041] Preferably, in the present invention, the organic amine in S2 is selected from any one or more of n-propylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-hexylamine, n-pentylamine, di-n-butylamine, trimethylamine, triethylamine, and tripropylamine.

[0042] Preferably, in the present invention, the molar ratio of 2-methylimidazole to the organic amine in S2 is (1:1) - (10:1).

[0043] Preferably, in the present invention, the molar ratio of zinc nitrate to 2-methylimidazole in S3 is (1:16) - (1:2).

[0044] Preferably, in the present invention, the washing solvent in S4 includes water, ethanol, acetone, etc., and is washed three times repeatedly; the vacuum drying specifically refers to vacuum drying at 50 - 80 °C for 8 - 12 h.

[0045] Preferably, in the present invention, the highly transition metal-doped imidazole zeolite framework in S4 is any one of Mn-ZIF-8, Fe-ZIF-8, Co-ZIF-8, Ni-ZIF-8, Cu-ZIF-8, Ru-ZIF-8, Rh-ZIF-8, Ir-ZIF-8, FeMn-ZIF-8, FeNi-ZIF-8, FeCo-ZIF-8, FeCu-ZIF-8, CoNi-ZIF-8, NiCu-ZIF-8, CoCu-ZIF-8, FeCoNi-ZIF-8, FeCoNiCu-ZIF-8, and FeCoNiCuRu-ZIF-8.

[0046] Preferably, in the present invention, for its structural characterization, the powder X-ray diffraction pattern has sharp diffraction peaks and is the same as the crystal structure of ZIF-8 without doping other transition metals.

[0047] Preferably, for the present invention, pore size distribution and specific surface area analysis are carried out. The powder X-ray diffraction pattern has sharp diffraction peaks and is the same as the crystal structure of ZIF-8 without doping other transition metals.

[0048] Preferably, for the present invention, elemental analysis is carried out. Element mapping in energy-dispersive X-ray spectroscopy shows that the doped transition metals are uniformly dispersed in the imidazole zeolite framework, and the content of the doped transition metals can be as high as 13.7 wt%.

[0049] Example 1

[0050] S1: By an ultrasonic-assisted method, 1.49 g of zinc nitrate hexahydrate and 0.073 g of nickel nitrate hexahydrate are dissolved in 50 mL of pure water to obtain metal salt solution 1;

[0051] S2: 3.3 g of 2-methylimidazole and 3 ml of n-butylamine are dissolved in 50 mL of pure water to obtain ligand solution 2;

[0052] S3: Under vigorous stirring, solution 1 is quickly poured into solution 2 for thorough mixing. After vigorous stirring for 2 h, it is left standing at room temperature for 24 h;

[0053] S4: After a certain precipitate is formed, the product is first centrifuged to remove the solvent, then washed 3 times with pure water, and finally dried in vacuum at 60 °C for 12 h to obtain Ni-doped zeolitic imidazolate framework Ni-ZIF-8.

[0054] S5: Figure 2 is the scanning electron micrograph of Ni-ZIF-8; Figure 3 is the transmission electron micrograph of Ni-ZIF-8; Figure 4 is the elemental mapping diagram in the energy-dispersive X-ray spectroscopy of Ni-ZIF-8, and it can be observed that Ni elements are uniformly distributed in the nanomaterial; Figure 5 is the powder X-ray diffraction pattern of Ni-ZIF-8, which can prove that the Ni-doped zeolitic imidazolate framework retains the high crystallinity of the original zeolitic imidazolate framework; Figure 6 is the N2 adsorption-desorption isotherm of Ni-ZIF-8, and the specific surface area of Ni-ZIF-8 can be calculated to be 1650 m 2 / g; Figure 7 is the micropore distribution curve of Ni-ZIF-8, which can prove that the Ni-doped zeolitic imidazolate framework has highly ordered micropores.

[0055] Example 2

[0056] S1: By an ultrasonic-assisted method, 1.49 g of zinc nitrate hexahydrate and 0.065 g of ruthenium(III) chloride trihydrate are dissolved in 50 mL of pure water to obtain metal salt solution 1;

[0057] S2: Dissolve 3.3 g of 2-methylimidazole and 3 ml of n-hexylamine in 50 mL of pure water to obtain ligand solution 2;

[0058] S3: Under vigorous stirring, quickly pour solution 1 into solution 2 for thorough mixing. After vigorously stirring for 2 h, let it stand at room temperature for 24 h;

[0059] S4: After a certain amount of precipitation is formed, first centrifuge the product to remove the solvent, then wash it 3 times with pure water, and finally vacuum dry it at 60 °C for 12 h to obtain Ru-doped zeolitic imidazolate framework Ru-ZIF-8.

[0060] S5: Figure 8 is the elemental mapping diagram in the energy-dispersive X-ray spectrum of Ru-ZIF-8, and it can be observed that the Ru element is evenly distributed in the nanomaterial.

[0061] Example 3

[0062] S1: By an ultrasound-assisted method, dissolve 1.49 g of zinc nitrate hexahydrate, 0.033 g of iron(III) chloride hexahydrate, and 0.037 g of nickel nitrate hexahydrate in 50 mL of pure water to obtain metal salt solution 1;

[0063] S2: Dissolve 3.3 g of 2-methylimidazole and 3 ml of n-butylamine in 50 mL of pure water to obtain ligand solution 2;

[0064] S3: Under vigorous stirring, quickly pour solution 1 into solution 2 for thorough mixing. After vigorously stirring for 2 h, let it stand at room temperature for 24 h;

[0065] S4: After a certain amount of precipitation is formed, first centrifuge the product to remove the solvent, then wash it 3 times with pure water, and finally vacuum dry it at 60 °C for 12 h to obtain FeNi-doped zeolitic imidazolate framework FeNi-ZIF-8.

[0066] Example 4

[0067] S1: By an ultrasound-assisted method, dissolve 1.49 g of zinc nitrate hexahydrate, 0.022 g of iron(III) chloride hexahydrate, 0.024 g of cobalt(II) nitrate hexahydrate, and 0.024 g of nickel nitrate hexahydrate in 50 mL of pure water to obtain metal salt solution 1;

[0068] S2: Dissolve 3.3 g of 2-methylimidazole and 3 ml of n-butylamine in 50 mL of pure water to obtain ligand solution 2;

[0069] S3: Under strong stirring, quickly pour solution 1 into solution 2 for thorough mixing. After vigorously stirring for 2 h, let it stand at room temperature for growth for 24 h;

[0070] S4: After a certain amount of precipitation has formed, the product is first centrifuged to remove the solvent, then washed three times with pure water, and finally dried in vacuo at 60 °C for 12 h to obtain FeCoNi-doped zeolitic imidazolate framework FeCoNi-ZIF-8.

[0071] It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0072] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent without departing from the scope of the technical solution of the present invention.

Claims

1. A method for preparing imidazole zeolite-like frameworks doped with high-content transition metals, characterized in that: It includes the following steps: S1: Dissolve zinc nitrate and another soluble metal salt in a solvent to obtain metal salt solution 1; S2: Dissolve 2-methylimidazole and an organic amine in a solvent to obtain ligand solution 2; S3: Mix and stir solution 1 and solution 2 at room temperature and react for a period of time; S4: After a certain precipitate is formed, centrifuge, wash, and vacuum dry the product in sequence to obtain a transition metal-doped zeolitic imidazolate framework nanomaterial.

2. The method for preparing an imidazole zeolite framework doped with a high content of transition metal according to claim 1, characterized in that: The soluble metal salt is selected from any one of MnSO4, Mn(CH3COO)2, MnCl2, FeCl2, FeSO4, FeCl3, Fe2(SO4)3, Fe(NO3)3, CoCl2, CoSO4, Co(NO3)2, NiCl2, NiSO4, Ni(NO3)2, Ni(CH3COO)2, CuCl2, CuSO4, Cu(CH3COO)2, Cu(NO3)2, RuCl3, RhCl3, IrCl3.

3. The method for preparing an imidazole zeolite framework doped with a high content of transition metal according to claim 1, characterized in that: The solvent is one of methanol, ethanol, and water.

4. A method for preparing a high-content transition metal-doped imidazole zeolite framework according to claim 1, characterized in that: The organic amine is selected from any one of n-propylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-hexylamine, n-pentylamine, di-n-butylamine, trimethylamine, triethylamine, and tripropylamine.

5. A method for preparing an imidazole zeolite framework doped with a high content of transition metal according to claim 1, characterized in that: The molar ratio of zinc nitrate to the soluble metal salt is (1:2) - (40:1).

6. The method for preparing an imidazole zeolite framework doped with a high content of transition metal according to claim 1, characterized in that: The molar ratio of 2-methylimidazole to the organic amine is (1:1) - (10:1).

7. The method for preparing a highly content transition metal-doped imidazole zeolite framework according to claim 1, wherein: The molar ratio of zinc nitrate to 2-methylimidazole is (1:16) - (1:2).

8. A method for preparing an imidazole zeolite framework doped with a high content of transition metal according to claim 1, characterized in that: The high-content transition metal-doped imidazole zeolite framework is any one of Mn-ZIF-8, Fe-ZIF-8, Co-ZIF-8, Ni-ZIF-8, Cu-ZIF-8, Ru-ZIF-8, Rh-ZIF-8, Ir-ZIF-8, FeMn-ZIF-8, FeNi-ZIF-8, FeCo-ZIF-8, FeCu-ZIF-8, CoNi-ZIF-8, NiCu-ZIF-8, CoCu-ZIF-8, FeCoNi-ZIF-8, FeCoNiCu-ZIF-8, FeCoNiCuRu-ZIF-8.

9. The method for preparing a highly content transition metal-doped imidazole zeolite framework according to claim 1, wherein: For the transition metal-doped imidazole zeolite framework, its powder X-ray diffraction pattern has sharp diffraction peaks and is the same as the crystal structure of ZIF-8 without doping other transition metals.

10. A method for preparing a highly content transition metal-doped imidazole zeolite framework according to claim 1, characterized in that: The transition metal-doped imidazole zeolite frameworks have a high specific surface area, in the range of 991-1888 m 2 / g.

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