CN113773517A

CN113773517A - General preparation method of multi-stage porous metal organic framework material

Info

Publication number: CN113773517A
Application number: CN202111168888.6A
Authority: CN
Inventors: 付昱; 翟旭
Original assignee: Shanghai Yihe Jiapeng New Material Technology Co ltd
Current assignee: Shanghai Yihe Jiapeng New Material Technology Co ltd
Priority date: 2021-10-08
Filing date: 2021-10-08
Publication date: 2021-12-10

Abstract

The invention discloses a general preparation method of a multi-stage porous metal organic framework material, which comprises the following steps: s1, preparing a metal cation solution and an organic ligand solution; s2, mixing the prepared metal cation solution and the organic ligand solution, and transferring the mixture into a high-pressure reaction kettle to crystallize for a certain time at a certain temperature; s3, separating the precipitate obtained by crystallization in the step S2 to obtain MOFs powder; s4, placing a platform in the lining of the closed high-pressure reaction kettle, placing the MOFs powder prepared in the step S3 on the platform, placing an etchant solution at the bottom of the lining of the reaction kettle, wherein the etchant solution is located below the platform and is not in contact with the MOFs powder on the platform, and etching at a certain temperature to obtain the HP-MOFs material. The general preparation method of the multistage porous metal organic framework material can quickly and effectively synthesize various multistage porous metal organic framework materials, and has the advantages of simple method, easiness in large-scale preparation, low cost and the like.

Description

General preparation method of multi-stage porous metal organic framework material

Technical Field

The invention relates to the technical field of metal organic framework materials, in particular to a general preparation method of a multi-stage porous metal organic framework material.

Background

Metal-organic frameworks (MOFs) are a new class of porous crystalline materials, which are constructed by metal ions or clusters and multifunctional organic ligands in a self-assembly mode, and the MOFs has a large specific surface area, adjustable pore size and a customizable framework, and these characteristics make them have great potential in the fields of catalysis, gas separation, sensing, and the like. Most of the reported MOFs have pore sizes limited to the micropore range (pore size less than 2 nm), which prevents the catalytic diffusion process from proceeding, especially when macromolecular substrates are involved; this greatly hinders their application prospects and industrialization progress. In order to solve the key problem, it is a feasible method to construct a mesoporous structure (with the pore diameter of 2-50 nm) in the original microporous MOFs frame, i.e. to form HP-MOFs, wherein micropores provide a large specific surface area, and mesopores are helpful for the mass transfer process.

The preparation method of HP-MOFs is mainly divided into direct synthesis and post-treatment. Currently, post-treatment based etching processes are of interest because they can maintain the structural integrity of the post-etch MOFs to some extent. In this approach, suitable etchants matching the structural features of the MOFs are typically required to achieve etching of the MOFs to create mesopores in the microporous MOFs. For example, MIL-100 can be H matched in molecular size to the MIL-100 pore structure₃PO₄And selectively etching to form mesopores in the original MIL-100. However, when the HCl molecular size is smaller than the MIL-100 window size, the MIL-100 backbone is completely dissolved. Therefore, the etching process of the MOFs is very difficult to control, and it is difficult to rapidly complete the etching of the MOFs, which limits the production efficiency and the wide-range preparation of the HP-MOFs.

Disclosure of Invention

The invention aims to provide a general preparation method of a multistage porous metal organic framework material, which can quickly and effectively synthesize various multistage porous metal organic framework materials.

In order to achieve the above object, the present invention provides a general method for preparing a multi-stage porous metal organic framework material, comprising the steps of,

s1, preparing a metal cation solution and an organic ligand solution;

s2, mixing the metal cation solution and the organic ligand solution prepared in the step S1, and transferring the mixture into a high-pressure reaction kettle to crystallize for a certain time at a certain temperature;

s3, separating the precipitate obtained by crystallization in the step S2 to obtain MOFs powder;

s4, placing a platform in the lining of the closed high-pressure reaction kettle, placing the MOFs powder prepared in the step S3 on the platform, placing an etchant solution at the bottom of the lining of the reaction kettle, wherein the etchant solution is located below the platform and is not in contact with the MOFs powder on the platform, and etching at a certain temperature to obtain the HP-MOFs material.

Preferably, in the step S1, the metal cation is Zn²⁺、Cu²⁺、Co²⁺、Ni²⁺、Mn²⁺、Fe²⁺、Pd²⁺、Pt²⁺、Ru² ⁺、Cd²⁺、Zr⁴⁺、Hf⁴⁺、Ti⁴⁺One kind of (1).

Preferably, in step S1, the organic ligand solution is one of terephthalic acid, naphthalenedicarboxylic acid, trimesic acid, oxalic acid, succinic acid, imidazole, pyridine, piperidine, fumaric acid, and 2-aminoterephthalic acid.

Preferably, in step S1, the concentration of the metal cation solution is 0.1-10 mmol/mL, and the concentration of the organic ligand solution is 0.1-10 mmol/mL.

Preferably, in step S1, the solvent used in the metal cation solution and the organic ligand solution is one pure solvent or a mixture of any two of N, N-dimethylformamide, absolute ethanol and water.

Preferably, in the step S2, the volume of the high-pressure reaction kettle is 50-100 mL.

Preferably, in the step S2, the crystallization temperature in the high-pressure reaction kettle is 25 to 150 ℃, and the crystallization time is 16 to 24 hours.

Preferably, in step S3, the method for separating the precipitate is centrifugation or filtration.

Preferably, in step S4, the etchant solution is a mixture of a volatile unstable acid or base etchant and a solvent, and the solvent is one or a mixture of water, ammonia water, trifluoroacetic acid, triethylamine, hydrochloric acid, acetic acid, nitric acid, acetonitrile, and methanol.

Preferably, in the step S4, the etching temperature is 60-200 ℃, and the etching time is 1-24 h.

According to the general preparation method of the multi-level porous metal organic framework material, MOFs powder is placed on a platform inside a reaction kettle, and the MOFs is etched by using steam of an etchant generated inside the reaction kettle at a high temperature, so that the required multi-level porous material can be quickly synthesized. The synthesis reaction can be realized by using conventional equipment, and the etchant solution can be repeatedly used for many times, so that the cost of the etchant is saved, and the method is very favorable for industrial mass production. The preparation method has the characteristics of simple method, easy preparation, low production cost, quick reaction time, high yield and the like, and is very suitable for large-scale industrial production.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 is an SEM photograph of a copper-trimesic acid framework (HKUST-1) prepared in example 1 of the present invention;

FIG. 2 is an XRD spectrum of copper-trimesic acid skeleton (HKUST-1) prepared in example 1 of the present invention;

FIG. 3 is an SEM photograph of a multi-stage porous copper-trimesic acid skeleton (HP-HKUST-1) prepared in example 1 of the present invention;

FIG. 4 is an XRD pattern of a multi-stage porous copper-trimesic acid skeleton (HP-HKUST-1) prepared in example 1 of the present invention;

FIG. 5 is a TEM image of a zirconium-terephthalic acid framework (Zr-UiO-66) prepared in example 2 of the present invention;

FIG. 6 is an XRD spectrum of a zirconium-terephthalic acid skeleton (Zr-UiO-66) prepared in example 2 of the present invention;

FIG. 7 is a TEM spectrum of a multi-stage porous zirconium-terephthalic acid skeleton (HP-Zr-UiO-66) prepared in example 2 of the present invention;

FIG. 8 is an XRD spectrum of a multi-stage porous zirconium-terephthalic acid skeleton (HP-Zr-UiO-66) prepared in example 2 of the present invention;

FIG. 9 is a TEM image of zinc-2-methylimidazole skeleton (ZIF-8) prepared in example 3 of the present invention;

FIG. 10 is an XRD spectrum of zinc-2-methylimidazole skeleton (ZIF-8) prepared in example 3 of the present invention;

FIG. 11 is a TEM spectrum of a multi-stage porous zinc-2-methylimidazole skeleton (HP-ZIF-8) prepared in example 3 of the present invention;

FIG. 12 is an XRD spectrum of a multi-stage porous zinc-2-methylimidazole skeleton (HP-ZIF-8) prepared in example 3 of the present invention;

FIG. 13 is an SEM image of an iron-fumaric acid skeleton (MIL-88A) prepared in example 4 of the present invention;

FIG. 14 is an XRD pattern of iron-fumaric acid skeleton (MIL-88A) prepared in example 4 of the present invention;

FIG. 15 is a TEM image of a multi-stage porous iron-fumaric acid skeleton (HP-MIL-88A) prepared in example 4 of the present invention;

FIG. 16 is an XRD pattern of a multi-stage porous iron-fumaric acid skeleton (HP-MIL-88A) prepared in example 4 of the present invention;

FIG. 17 is a TEM image of a hafnium-terephthalic acid framework (UiO-66(Hf)) prepared in example 5 of the present invention;

FIG. 18 is an XRD spectrum of a hafnium-terephthalic acid framework (UiO-66(Hf)) prepared in example 5 of the present invention;

FIG. 19 is a TEM spectrum of a multi-stage porous hafnium-terephthalic acid framework (HP-UiO-66(Hf)) prepared in example 5 of the present invention;

FIG. 20 is an XRD spectrum of a multi-stage porous hafnium-terephthalic acid skeleton (HP-UiO-66(Hf)) prepared in example 5 of the present invention;

FIG. 21 is a TEM image of a titanium-2-amino terephthalic acid skeleton (MIL-125-NH2) prepared in example 6 of the present invention;

FIG. 22 is an XRD spectrum of titanium-2-amino terephthalic acid skeleton (MIL-125-NH2) prepared in example 6 of the present invention;

FIG. 23 is a TEM spectrum of multi-stage porous titanium-2-amino terephthalic acid skeleton (HP-MIL-125-NH2) prepared in example 6 of the present invention;

FIG. 24 is an XRD spectrum of multi-stage porous titanium-2-amino terephthalic acid skeleton (HP-MIL-125-NH2) prepared in example 6 of the present invention.

Detailed Description

The technical solution of the present invention is further illustrated by the accompanying drawings and examples.

A general preparation method of a multi-stage porous metal organic framework material comprises the following steps,

s1, preparing a metal cation solution and an organic ligand solution; the metal cation being Zn²⁺、Cu²⁺、Co²⁺、Ni²⁺、Mn² ⁺、Fe²⁺、Pd²⁺、Pt²⁺、Ru²⁺、Cd²⁺、Zr⁴⁺、Hf⁴⁺、Ti⁴⁺One kind of (1). The use of transition metal elements having a valence of two or four enables the formation of stable metal-organic framework compounds with organic ligands. The organic ligand solution is one of terephthalic acid, naphthalenedicarboxylic acid, trimesic acid, oxalic acid, succinic acid, imidazole, pyridine, piperidine, fumaric acid and 2-aminoterephthalic acid, and the organic ligand and metal cations can form a metal-organic framework compound which is stable, novel in structure and adjustable in appearance. According to the theory of soft and hard acids and bases, the metal cations of hard acids react in combination with the organic ligands of hard bases to form stable MOFs.

The concentration of the metal cation solution is 0.1-10 mmol/mL, the concentration of the organic ligand solution is 0.1-10 mmol/mL, the nano-scale or micron-scale metal organic framework material with high crystallinity can be generated, and the yield of the synthesized nano/micron-scale metal organic framework material is high. The solvent used in the metal cation solution and the organic ligand solution is one pure solvent or a mixed solvent of any of N, N-dimethylformamide, absolute ethyl alcohol and water. N, N-dimethylformamide, absolute ethyl alcohol and water can also be used as ligands to coordinate with metal cations or form hydrogen bonds with organic ligands, so that the synthesized nano/micron-sized metal organic framework material has nano and micron pores.

S2, mixing the metal cation solution and the organic ligand solution which are prepared in the step S1, and transferring the mixture into a high-pressure reaction kettle to crystallize for a certain time at a certain temperature. The volume of the high-pressure reaction kettle is 50-100 mL, and the inner lining of the high-pressure reaction kettle is white polytetrafluoroethylene which is resistant to high temperature, high pressure and acid and alkali. The crystallization temperature in the high-pressure reaction kettle is 25-150 ℃, and the crystallization time is 16-24 h. The metal cation solution and the organic ligand solution react in a high-temperature high-pressure reaction kettle, which is beneficial to the crystallization of MOFs products.

S3, separating the precipitate obtained by crystallization in the step S2 to obtain the MOFs powder. The method for separating the precipitate is centrifugation or filtration.

S4, placing a platform in the lining of the closed high-pressure reaction kettle, placing the MOFs powder prepared in the step S3 on the platform, placing an etchant solution at the bottom of the lining of the reaction kettle, wherein the etchant solution is located below the platform and is not in contact with the MOFs powder on the platform, and etching at a certain temperature to obtain the HP-MOFs material. The etchant solution is a mixed solution of volatile unstable acid or alkali etchant and solvent, wherein the solvent is one or a mixture of water, ammonia water, trifluoroacetic acid, triethylamine, hydrochloric acid, acetic acid, nitric acid, acetonitrile and methanol. The etching temperature is 60-200 ℃, and the etching time is 1-24 h. The etchant volatilizes under the action of high temperature, the MOFs powder is etched by utilizing the volatilized steam atmosphere, and the steam can be uniformly diffused into the MOFs skeleton and break the coordination bond between metal and ligand, so that the multi-level porous metal organic skeleton material can be quickly generated.

Example 1

Preparing a copper nitrate trihydrate solution with the concentration of 0.33 mmol/mL and a trimesic acid solution with the concentration of 0.015 mmol/mL, wherein the solvents are H₂O/DMF/EtOH, volume ratio =1:1: 1. 0.6 g of copper nitrate trihydrate was dissolved in 2.5 mL of DMF and 2.5 mL of H₂Preparing a copper nitrate trihydrate solution in a mixed solvent consisting of O and 2.5 mL of EtOH; 0.3 g of trimesic acid was dissolved in 2.5 mL of DMF and 2.5 mL of H₂O and 2.5 mL of EtOH to prepare a trimesic acid solution.

In a 20 mL scintillation vial, the two solutions were mixed and a few drops of concentrated hydrochloric acid were added for ultrasonic dissolution until the solution became clear, followed by crystallization in an oven at 85 ℃ for 24 h.

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in FIG. 1, the resulting HKUST-1 was of an octahedral structure. As shown in FIG. 2, the spectrum of the synthesized HKUST-1 was consistent with the structure of the model, demonstrating that HKUST-1 was successfully synthesized.

The HKUST-1 powder is placed on the upper part of a platform of a lining of a high-pressure reaction kettle, 10 mL of 0.1 mol/L HCl aqueous solution is placed at the bottom of the platform, the platform is etched in a 120 ℃ oven for 6 hours, and the obtained powder is characterized. As shown in FIG. 3, the resulting sample is denoted as HP-HKUST-1 and is still of octahedral morphology, except for nanopores with many mesoporous features on the surface. As shown in FIG. 4, the spectrum of the synthesized HP-HKUST-1 was consistent with that of the original one, demonstrating that the crystal structure of the obtained HP-HKUST-1 was still well maintained.

Example 2

Preparing a zirconium tetrachloride solution of 0.1 mmol/mL and a terephthalic acid solution of 0.1 mmol/mL: dissolving 116.7 mg of zirconium tetrachloride solid in 5 mL of N, N dimethylformamide to prepare a zirconium tetrachloride solution; dissolving 83 mg of terephthalic acid in 5 mL of N, N-dimethylformamide to prepare a terephthalic acid solution;

in a 20 mL scintillation vial, the two solutions were mixed and sonicated, followed by the addition of 3 mL of glacial acetic acid. Finally, the mixture is placed in an oven at 120 ℃ for crystallization for 24 hours.

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in FIG. 5, the obtained UiO-66 crystal is of regular octahedral morphology. As shown in FIG. 6, the spectrum of the synthesized UiO-66 is consistent with the simulated structure, which proves that the UiO-66 crystal is successfully synthesized.

And placing the UiO-66 powder on the upper part of a platform of a lining of a high-pressure reaction kettle, placing a mixed solution of 5 mL of ethanol and 3 mL of ammonia water at the bottom, etching for 3 h in an oven at 85 ℃, and characterizing the obtained powder. The resulting sample, shown in FIG. 7, was designated as HP-UiO-66 and still maintained the octahedral morphology of the original UiO-66, except that the nanopores had many mesoporous features on their surface, demonstrating that hierarchical pore UiO-66 was successfully synthesized. As shown in FIG. 8, the spectrum of the synthesized HP-UiO-66 was consistent with that of the original one, demonstrating that the crystal structure of the obtained HP-UiO-66 was still well maintained.

Example 3

Preparing a 5 mmol/mL zinc nitrate hexahydrate solution and a 40 mmol/mL dimethylimidazole solution: dissolving 1.487 g of solid zinc nitrate hexahydrate in 30 mL of deionized water to prepare a zinc nitrate hexahydrate solution; dissolving 3.28 g of dimethyl imidazole in 30 mL of deionized water to prepare a dimethyl imidazole solution;

the two solutions were mixed and dissolved by sonication in a 100 mL beaker, followed by crystallization at 85 ℃ for 24 h.

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in FIG. 9, the ZIF-8 crystal obtained was a dodecahedral morphology. As shown in FIG. 10, the spectrum of the synthesized ZIF-8 was consistent with that of the simulated structure, demonstrating that ZIF-8 was successfully synthesized.

And (3) placing ZIF-8 powder on the upper part of a platform of a high-pressure reaction kettle lining, placing 10 mL of 0.1 mol/L HCl aqueous solution at the bottom, etching for 6 hours in an oven at 85 ℃, and characterizing the obtained powder. As shown in fig. 11, the resulting sample was denoted HP-ZIF-8 and still maintained the dodecahedral morphology of the original ZIF-8, except for nanopores with many mesoporous features on the surface, demonstrating the successful synthesis of hierarchical pore ZIF-8. As shown in fig. 12, the synthesized HP-ZIF-8 showed a spectrum consistent with that of the original one, demonstrating that the crystal structure of the obtained HP-ZIF-8 was still well maintained.

Example 4

Preparing 0.4 mmol/mL ferric trichloride hexahydrate solution and 0.4 mmol/mL fumaric acid solution: dissolving 0.540 g of ferric trichloride hexahydrate in 5 mL of N, N-dimethylformamide to prepare a ferric trichloride hexahydrate solution; dissolving 0.252 g of fumaric acid in 5 mL of N, N-dimethylformamide to prepare a fumaric acid solution;

the two solutions were mixed and dissolved ultrasonically in a 20 mL scintillation vial, followed by crystallization in an oven at 85 ℃ for 16 h.

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in fig. 13, the resulting MIL-88A crystals were spindle-shaped in morphology. As shown in fig. 14, the synthesized MIL-88A spectrum was consistent with the simulated structure, demonstrating that MIL-88A was successfully synthesized.

The MIL-88A powder is placed on the upper portion of a platform of a high-pressure reaction kettle lining, 10 mL of 0.1M HCl aqueous solution is placed at the bottom of the platform, etching is carried out in an oven at 85 ℃ for 6 hours, and the obtained powder is characterized. As shown in fig. 15, the resulting sample was denoted HP-MIL-88A and still maintained the morphology of the original MIL-88A, except that the nanopores had many mesoporous features on their surface, demonstrating that the multiwell MIL-88A was successfully synthesized. As shown in FIG. 16, the synthesized HP-MIL-88A showed a spectrum consistent with that of the original one, demonstrating that the crystal structure of the obtained HP-MIL-88A was still well maintained.

Example 5

Preparing a hafnium tetrachloride solution of 0.1 mmol/mL and a terephthalic acid solution of 0.1 mmol/mL: 160.0 mg of hafnium tetrachloride solid is dissolved in 5 mL of N, N dimethylformamide to prepare a hafnium tetrachloride solution; dissolving 83 mg of terephthalic acid in 5 mL of N, N-dimethylformamide to prepare a terephthalic acid solution;

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in FIG. 17, the obtained UiO-66(Hf) crystals were in the shape of regular octahedron. As shown in FIG. 18, the spectrum of the synthesized UiO-66(Hf) was consistent with the simulated structure, demonstrating that UiO-66(Hf) was successfully synthesized.

And placing the UiO-66 powder on the upper part of a platform of a lining of a high-pressure reaction kettle, placing a mixed solution of 5 mL of ethanol and 3 mL of ammonia water at the bottom, etching for 3 h in an oven at 85 ℃, and characterizing the obtained powder. As shown in FIG. 7, the resulting sample is denoted as HP-UiO-66(Hf) and still maintains the octahedral morphology of the original UiO-66(Hf), except that nanopores with many mesoporous features (2-50 nm) on the surface demonstrate the successful synthesis of hierarchical pore UiO-66 (Hf). As shown in FIG. 20, the spectrum of the synthesized HP-UiO-66 was consistent with that of the original one, demonstrating that the crystal structure of the resulting HP-UiO-66(Hf) was still well maintained.

Example 6

Preparing 0.4 mmol/mL isopropyl titanate solution and 0.6 mmol/mL 2-amino terephthalic acid solution: adding 0.6 mL of isopropyl titanate into a solvent consisting of 18 mL of N, N-dimethylformamide and 2 mL of methanol to prepare an isopropyl titanate solution; dissolving 0.56 g of 2-amino terephthalic acid in a solvent consisting of 18 mL of N, N-dimethylformamide and 2 mL of methanol to prepare a 2-amino terephthalic acid solution;

the two solutions were mixed and dissolved by sonication in a 100 mL stainless steel reactor and finally crystallized in an oven at 150 ℃ for 24 h.

And (4) separating the precipitate after the reaction is finished, and carrying out characterization after collecting the precipitate by using a centrifugal tube. As shown in FIG. 21, MIL-125-NH was obtained₂The crystal is in a disc shape. As shown in FIG. 22, the synthesized MIL-125-NH₂The spectrum of (A) was consistent with the simulated structure, demonstrating MIL-125-NH₂Was successfully synthesized.

Mixing MIL-125-NH₂And placing the powder on the upper part of a platform of a lining of a high-pressure reaction kettle, placing a mixed solution of 5 mL of ethanol and 3 mL of ammonia water at the bottom, etching for 3 h in an oven at 85 ℃, and characterizing the obtained powder. As shown in FIG. 7, the sample obtained is designated as HP-MIL-125-NH₂And still maintain the original MIL-125-NH₂The disc shape is different from that of a nano-pore with a plurality of mesoporous characteristics on the surface, and the multi-level porous MIL-125-NH is proved₂Was successfully synthesized. As shown in FIG. 24, the synthesized HP-MIL-125-NH₂The spectrum of (A) was consistent with that of the original, demonstrating that the resulting HP-MIL-125-NH was obtained₂The crystal structure of (a) is still well maintained.

Therefore, the general preparation method of the multi-stage porous metal organic framework material can quickly and effectively synthesize various multi-stage porous metal organic framework materials, has the advantages of simple method, easy mass preparation, low cost and the like, and is very suitable for large-scale industrial production.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the invention without departing from the spirit and scope of the invention.

Claims

1. A general preparation method of a multistage porous metal organic framework material is characterized by comprising the following steps: comprises the following steps of (a) carrying out,

s1, preparing a metal cation solution and an organic ligand solution;

2. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S1, the metal cation is Zn²⁺、Cu²⁺、Co²⁺、Ni²⁺、Mn²⁺、Fe²⁺、Pd²⁺、Pt²⁺、Ru²⁺、Cd²⁺、Zr⁴⁺、Hf⁴⁺、Ti⁴⁺One kind of (1).

3. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S1, the organic ligand solution is one of terephthalic acid, naphthalenedicarboxylic acid, trimesic acid, oxalic acid, succinic acid, imidazole, pyridine, piperidine, fumaric acid, and 2-aminoterephthalic acid.

4. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S1, the concentration of the metal cation solution is 0.1-10 mmol/mL, and the concentration of the organic ligand solution is 0.1-10 mmol/mL.

5. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S1, the solvent used in the metal cation solution and the organic ligand solution is one pure solvent or a mixture of any two of N, N-dimethylformamide, absolute ethyl alcohol and water.

6. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S2, the volume of the high-pressure reaction kettle is 50-100 mL.

7. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S2, the crystallization temperature in the high-pressure reaction kettle is 25-150 ℃, and the crystallization time is 16-24 h.

8. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in step S3, the method for separating the precipitate is centrifugation or filtration.

9. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S4, the etchant solution is a mixture of a volatile unstable acid or base etchant and a solvent, and the solvent is one or a mixture of water, ammonia water, trifluoroacetic acid, triethylamine, hydrochloric acid, acetic acid, nitric acid, acetonitrile, and methanol.

10. The method for preparing a multi-stage porous metal organic framework material according to claim 1, wherein the method comprises the following steps: in the step S4, the etching temperature is 60-200 ℃, and the etching time is 1-24 h.