CN115216052B - A preparation method of hierarchically porous MOFs material maintaining a complete framework - Google Patents

Abstract

The invention discloses a preparation method of a hierarchical pore MOFs material with a complete framework, which comprises the following steps: dispersing MOFs material into a solvent, and marking as feed liquid A; dispersing a template agent into a solvent, and marking as a feed liquid B; mixing the feed liquid A and the feed liquid B to form a mixed dispersion; introducing the mixed dispersion obtained in the step S3 into a spray dryer for spray drying to obtain a mixed cluster body of MOFs material and template agent; and (3) dissolving the mixed cluster body obtained in the step (S4) in a liquid phase medium for etching, removing a template agent, and obtaining a product through centrifugation, washing and drying. The invention adopts spray drying technology, and then obtains the hierarchical pore MOFs material with regular morphology and controllable pore diameter through steps such as etching. The preparation method effectively realizes the preparation of the hierarchical pore MOFs material, and more than or equal to 70% of particles are in a spherical shape, and the particle size range of the particles is 1-10 mu m; the preparation process adopted by the invention is simple and is easy to realize large-scale production.

Description

A preparation method of hierarchically porous MOFs material maintaining a complete framework

technical field

The invention relates to the technical field of preparation of metal-organic framework materials; more specifically, it relates to a preparation method of a hierarchically porous MOFs material that maintains a complete framework.

Background technique

In the past two decades, MOFs (abbreviation for metal-organic framework materials), as a new type of functional material, have attracted much attention due to their high specific surface area, low crystal density, permanent porosity and rich topological structure. It has attracted extensive attention from domestic and foreign research scholars. At present, MOFs materials have shown great application prospects in the fields of gas storage, adsorption separation, drug delivery, energy conversion, supercapacitors, and catalysis.

Most of the reported MOFs materials are microporous structures, and only a few MOFs materials have mesoporous structures. Although the pore structure of the material itself is conducive to the adsorption and separation of small molecules, it also hinders the rapid diffusion of molecules and the entry of larger molecules such as reactant molecules, product molecules, reaction intermediates, and large-sized drug molecules into the pores of MOFs. As a result, the practical application of MOFs materials has been greatly limited, and the emergence of hierarchically porous MOFs has opened up a new way to solve the above problems.

Hierarchical porous MOFs materials refer to MOFs materials with at least two pore structures of micropores, mesopores and macropores. The existence of small mesopores makes the material still retain a high specific surface area and porosity, while the introduction of other mesopores and macropores is conducive to the rapid diffusion and free transport of guest molecules inside the pores. In addition, the introduction of mesoporous and macroporous structures makes the hierarchically porous MOFs materials have larger pore volumes and thus higher adsorption capacity.

At present, the methods for preparing hierarchically porous MOFs materials mainly include extended ligand method, mixed ligand method, post-processing method and so on. The extended ligand method is to use a long ligand with a large size and structure to combine with the metal center to form a larger pore; the post-treatment method is to remove part of the ligand or metal center by heat treatment to form defects. The operation procedures of these methods are very different, so the morphology and function of the formed hierarchical porous MOFs materials are also very different, but the operation process is easy to lead to the collapse of the MOFs material itself. Therefore, it is necessary to provide a method for preparing hierarchically porous MOFs materials that maintain a complete framework with simple process, low energy consumption, short preparation time, controllable product particle size, and relatively uniform morphology and pore size.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a hierarchically porous MOFs material that maintains a complete framework. The method adopts spray drying technology, and then obtains hierarchically porous MOFs materials with regular morphology and controllable pore size through steps such as etching. The method of the invention effectively realizes the preparation of the multi-level porous MOFs material, and more than 70% of the particles are spherical in shape, and the particle size range is 1-10 μm; the preparation process adopted in the invention is simple, and it is easy to realize large-scale production.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

S1. Disperse the MOFs material into the solvent, which is recorded as material liquid A;

S2, disperse the templating agent into the solvent, and record it as material liquid B;

S3, mixing feed liquid A and feed liquid B to form a mixed dispersion;

S4. Pass the mixed dispersion obtained in step S3 into a spray dryer for spray drying to obtain mixed clusters of MOFs materials and templating agents;

S5. Dissolving the mixed clusters obtained in step S4 in a liquid medium for etching, removing the template agent, centrifuging, washing, and drying to prepare a multi-level porous MOFs material.

As a further improvement of the technical solution, in steps S1 and S2, the solvent is selected from one or more of the following substances: water, methanol, ethanol, N,N-dimethylformamide, toluene, tetrahydrofuran, ethylene glycol alcohol, cyclohexane.

Preferably, in step S1, the particle size of the MOFs material is 1-100 nm; preferably, the particle size of the MOFs material is 5-50 nm.

Preferably, in step S1, the solid content of the feed solution A is 1-10 wt%, preferably 2-5 wt%.

As a further improvement of the technical solution, in step S2, the template agent is selected from one or more of the following substances: polystyrene, silicon dioxide, mesoporous silica, mesoporous zeolite, alumina, hexadecane Alkyltrimethylammonium bromide, dodecanoic acid, F127, N,N-dimethyloctadecylamine, sodium 4-dodecylbenzoate.

Preferably, in step S2, the particle size of the template is 20-600 nm; preferably, the particle size of the template is 50-500 nm.

Preferably, in step S2, the solid content of the feed solution B is 1-8 wt%, preferably 2-5 wt%.

As a further improvement of the technical solution, in step S3, the mass ratio of the feed liquid A to the feed liquid B is 3:1-10:1.

Preferably, in step S3, ultrasonic treatment is used for 4-6 minutes when the feed liquid A and feed liquid B are mixed.

As a further improvement of the technical solution, in step S4, a peristaltic pump is used to pass the mixed dispersion into the spray dryer.

Preferably, in step S4, the compressed air velocity during the spray drying process is 300-800 L/h; more preferably, the compressed air velocity during the spray drying process is 400-650 L/h.

Preferably, in step S4, the input speed of the mixed dispersion during the spray drying process is 6-30 mL/min; more preferably, the input speed of the mixed dispersion during the spray drying process is 10-23 mL/min.

Preferably, in step S4, the temperature at the nozzle is 90-160°C during the spray drying process; more preferably, the temperature at the nozzle is 100-140°C during the spray drying process.

As a further improvement of the technical solution, in step S5, the liquid phase medium is selected from one or more of the following substances: sodium hydroxide, hydrofluoric acid, toluene, N,N-dimethylformamide, tetrahydrofuran, ethanol.

Preferably, in step S5, the ratio of the mixed clusters to the liquid medium is 1.5-6 mg: 1 mL; preferably, the ratio of the mixed clusters to the liquid medium is 2-4.5 mg: 1 mL.

Preferably, in step S5, the etching reaction conditions are heating and stirring, the heating temperature is 25-100° C., and the reaction time is 0.5-10 h.

Preferably, in step S5, the rotation speed of the centrifugation is 8000-12000rpm, and the time is 5-10min.

Any range recited in the present invention includes the endpoints and any value between the endpoints and any sub-range formed by the endpoints or any value between the endpoints.

Unless otherwise specified, each raw material in the present invention can be purchased commercially, and the equipment used in the present invention can be carried out by using conventional equipment in the field or referring to the prior art in the field.

Compared with the prior art, the present invention has the following beneficial effects:

1) Regarding the preparation of hierarchically porous MOFs materials in the prior art, it is usually difficult to control the size of the pores, and it is difficult to prepare MOFs with at least two pore structures in micropores, mesopores and macropores while maintaining a complete MOFs framework Material. The invention adopts the method of combining the spray drying process and the etching method, through the close arrangement of the particles of the MOFs material in the spray drying process, the mesopores formed between the particles and the etching method to remove the macropores formed by the template agent, A hierarchical porous MOFs material with micro/mesopores, controllable mesopores and macropores simultaneously exists in the material itself, and ≥70% of the particles are spherical.

2) The preparation method of the present invention has a wide range of applications, and a variety of MOFs materials and templates can be used as raw materials for the method; and the etching method can easily and gently remove the templates to ensure the integrity of the MOFs material skeleton in the process .

3) The present invention provides a simple method for regulating the diameter of the macropores in the hierarchically porous MOFs material, and the method only needs to adjust one process condition to realize the controllable preparation. That is, the preparation of MOFs materials with different sizes of macropores can be achieved by spray-drying templates with different particle sizes and MOFs materials.

4) The technological process used in the present invention is simple, the experimental process is easy to operate, the production efficiency is high, and it is easy to realize large-scale production.

Description of drawings

Below in conjunction with accompanying drawing, specific embodiment of the present invention is described in further detail

Fig. 1 shows the scanning electron microscope (SEM) picture of the mixed cluster body and hierarchical hole ZIF-8 that the embodiment of the present invention 1 gains;

Fig. 2 shows the particle size distribution figure of the hierarchical porous ZIF-8 that the embodiment of the present invention 1 gains;

Fig. 3 shows the SEM image of the mixed cluster body and hierarchical pore ZIF-8 obtained in Example 4 of the present invention;

Fig. 4 shows the SEM image of the mixed cluster body and hierarchical pore ZIF-8 obtained in Example 6 of the present invention;

Fig. 5 shows the SEM image of the mixed cluster body and hierarchical pore ZIF-8 obtained in Example 7 of the present invention;

Fig. 6 shows the SEM figure of the product obtained in comparative example 1 of the present invention;

Fig. 7 shows the SEM figure of the product obtained in comparative example 2 of the present invention;

Figure 8 shows the SEM image of the product obtained in Comparative Example 3 of the present invention.

Detailed ways

In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

In the present invention, the term "hierarchical pore" refers to the simultaneous presence of at least two pore structures of micropores, mesopores and macropores.

In the present invention, the term "micropore" refers to a pore with a diameter of less than 2 nm.

In the present invention, the term "mesoporous" refers to pores with a diameter of 2-50 nm.

In the present invention, the term "macropore" refers to a pore with a diameter greater than 50 nm.

As an aspect of the present invention, a method for preparing a hierarchically porous MOFs material that maintains a complete framework of the present invention comprises the following steps:

S1. Disperse the MOFs material into the solvent, which is recorded as material liquid A;

S2, disperse the templating agent into the solvent, and record it as material liquid B;

S3, mixing feed liquid A and feed liquid B to form a mixed dispersion;

S4. Pass the mixed dispersion obtained in step S3 into a spray dryer for spray drying to obtain mixed clusters of MOFs materials and templating agents;

S5. Dissolving the mixed clusters obtained in step S4 in a liquid medium for etching, removing the template agent, centrifuging, washing, and drying to prepare a multi-level porous MOFs material.

According to some embodiments of the present invention, in steps S1 and S2, the solvent is selected from one or more of the following substances: water, methanol, ethanol, N,N-dimethylformamide, toluene, tetrahydrofuran, Ethylene glycol, cyclohexane.

According to some embodiments of the present invention, in step S1, the particle size of the MOFs material is 1-100 nm; preferably, the particle size of the MOFs material is 5-50 nm.

According to some embodiments of the present invention, in step S1, the solid content of the feed solution A is 1-10 wt%.

According to some preferred embodiments of the present invention, in step S1, the solid content of the feed liquid A is 2-5 wt%.

According to some embodiments of the present invention, in step S2, the template agent is selected from one or more of the following substances: polystyrene, silicon dioxide, mesoporous silica, mesoporous zeolite, alumina, Cetyltrimethylammonium Bromide, Lauryl Acid, F127, N,N-Dimethyloctadecylamine, Sodium 4-Dodecylbenzoate.

According to some embodiments of the present invention, in step S2, the particle size of the template is 20-600 nm; preferably, the particle size of the template is 50-500 nm.

According to some embodiments of the present invention, in step S2, the solid content of the feed liquid B is 1-8 wt%, preferably 2-5 wt%.

According to some embodiments of the present invention, in step S3, the mass ratio of the feed liquid A to the feed liquid B is 3:1-10:1.

According to some embodiments of the present invention, in step S3, ultrasonic treatment is used for 4-6 minutes when the feed liquid A and feed liquid B are mixed.

According to some embodiments of the present invention, in step S4, a peristaltic pump is used to pass the mixed dispersion into the spray dryer.

According to some embodiments of the present invention, in step S4, the compressed air velocity during the spray drying process is 300-800 L/h.

According to some preferred embodiments of the present invention, the compressed air velocity during the spray drying process is 400-650 L/h.

According to some embodiments of the present invention, in step S4, the input speed of the mixed dispersion in the spray drying process is 6-30 mL/min.

According to some preferred embodiments of the present invention, the input speed of the mixed dispersion in the spray drying process is 10-23 mL/min.

According to some embodiments of the present invention, in step S4, the temperature at the nozzle during the spray drying process is 90-160°C.

According to some preferred embodiments of the present invention, the temperature at the nozzle during the spray drying process is 100-140°C.

According to some embodiments of the present invention, in step S5, the liquid phase medium is selected from one or more of the following substances: sodium hydroxide, hydrofluoric acid, toluene, N,N-dimethylformamide, Tetrahydrofuran, ethanol.

According to some embodiments of the present invention, in step S5, the ratio of the mixed cluster body to the liquid medium is 1.5-6mg: 1mL.

According to some preferred embodiments of the present invention, the ratio of the mixed clusters to the liquid medium is 2-4.5mg: 1mL.

According to some embodiments of the present invention, in step S5, the etching reaction conditions are heating and stirring, the heating temperature is 25-100° C., and the reaction time is 0.5-10 h.

According to some embodiments of the present invention, in step S5, the rotation speed of the centrifugation is 8000-12000 rpm, and the time is 5-10 min.

Example 1

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of material liquid A: prepare 100 mL of ZIF-8 dispersion with a solid content of 2 wt%, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 20 nm.

2) Preparation of feed liquid B: prepare 25 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 300 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 17.1mL/min, the compressed air velocity is 601L/h, The temperature is 110°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 80° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 3.75 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

In Figure 1, (a) shows the SEM image of the mixed clusters obtained by spray drying, 80% of the clusters are spherical in shape, and the particle size range is 1-10 μm; in Figure 1, (b) shows It is the topography diagram of the hierarchically porous ZIF-8 obtained after etching, and the diameter of the macropore is about 300 nm, which is consistent with the particle size of the polystyrene template used.

Figure 2 shows the pore size distribution diagram of the obtained hierarchically porous ZIF-8, where the existence of micropores and mesopores can be seen.

Example 2

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of material liquid A: prepare 100 mL of ZIF-8 dispersion with a solid content of 2 wt%, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 20 nm.

2) Preparation of feed liquid B: prepare 25 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 300 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 13.3mL/min, the compressed air velocity is 473L/h, The temperature is 100°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 70° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 3 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

By changing the parameters of spray drying, the morphology of the obtained hierarchical porous ZIF-8 is well maintained, most of which are spherical, and the diameter of the large pores is about 300nm.

Example 3

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of material liquid A: prepare 90 mL of ZIF-8 dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 20 nm.

2) Preparation of feed solution B: prepare 30 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 300 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 17.1mL/min, the compressed air velocity is 670L/h, The temperature is 120°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 80° C. and stirred for 1.5 h, wherein the ratio of polystyrene to DMF was 3.75 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

The macropore distribution of the hierarchically porous ZIF-8 obtained in this example is wider, and the pore diameter is about 300 nm.

Example 4

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of material liquid A: prepare 100 mL of ZIF-8 dispersion with a solid content of 2 wt%, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 20 nm.

2) Preparation of feed solution B: prepare 25 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 400 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 17.1mL/min, the compressed air velocity is 601L/h, The temperature is 100°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 80° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 3.75 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

In Figure 3, (a) shows the SEM image of the mixed clusters obtained by spray drying, 80% of the clusters are spherical in shape, and the particle size ranges from 1 to 10 μm. In Fig. 3, (b) and (c) show the SEM images of the hierarchically porous ZIF-8 obtained after etching, and the macropore diameter of the hierarchically porous ZIF-8 obtained in this embodiment is about 400 nm.

Example 5

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of feed liquid A: prepare 100 mL of ZIF-8 dispersion with a solid content of 3 wt %, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 20 nm.

2) Preparation of feed solution B: prepare 25 mL of polystyrene dispersion with a solid content of 3 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 400 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 17.1mL/min, the compressed air velocity is 414L/h, The temperature is 100°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 80° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 2.5 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

The hierarchically porous ZIF-8 obtained in this example is similar to Example 1.

Example 6

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of feed solution A: prepare 100 mL of ZIF-8 dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 30 nm.

2) Preparation of feed solution B: prepare 25 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 400 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 20.9mL/min, the compressed air velocity is 601L/h, The temperature is 100°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 90° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 3.75 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

In Figure 4, (a) shows the SEM image of the mixed clusters obtained by spray drying, 80% of the clusters are spherical in shape, and the particle size ranges from 1 to 10 μm.

In Fig. 4, (b) shows the SEM image of the hierarchically porous ZIF-8 obtained after etching, the diameter of the macropore is about 400nm, the particle size of the material liquid A is changed in this embodiment, after the template is removed by etching Still can maintain the intact hierarchical porous ZIF-8 framework.

Example 7

A method for preparing a hierarchically porous MOFs material that maintains a complete framework, comprising the steps of:

1) Preparation of feed solution A: prepare 100 mL of ZIF-8 dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of ZIF-8 in the dispersion is 15 nm.

2) Preparation of feed solution B: prepare 25 mL of polystyrene dispersion with a solid content of 2 wt %, the dispersion medium is water, and the particle size of polystyrene in the dispersion is 100 nm.

3) Mix the material liquid A and the material liquid B, and ultrasonically mix for 5 minutes to obtain a mixed dispersion.

4) Pass the mixed dispersion into the spray dryer with a peristaltic pump for spray drying; the process parameters used for spray drying are: the input speed of the mixed dispersion is 17.1mL/min, the compressed air velocity is 601L/h, The temperature is 100°C, and mixed clusters are obtained

5) The mixed clusters were dissolved in DMF solution, placed in a water bath at 80° C. and stirred for 1 h, wherein the ratio of polystyrene to DMF was 3.75 mg/mL. The obtained product was washed by centrifugation, once with DMF, and twice with methanol, and the obtained wet solid was dried in a vacuum oven at 60° C. for 12 hours to obtain hierarchically porous ZIF-8.

In Fig. 5, (a) shows the SEM image of the mixed clusters obtained by spray drying, 80% of the clusters are spherical in shape, and the particle size ranges from 1 to 10 μm. In Fig. 5, (b) shows the SEM image of the hierarchically porous ZIF-8 obtained after etching, and the diameter of the macropore is about 100 nm.

Example 8

Repeat Example 1, the only difference is that in step 1), the ZIF-8 uses MIL-101, UiO-66, ZIF-67, ZIF-90, MOF-801, MIL-100, MIL-53 , UiO-66-NH ₂ , UiO-66-SO ₃ H, and UiO-66-COOH instead.

The result is similar to Example 1.

Example 9

Repeat Example 1, the only difference is that in step 1), the ZIF-8 is replaced by one of HKUST-1, MOF-5, and MOF-74; the dispersion medium is ethanol. In step 2), the dispersion medium is ethanol.

The result is similar to Example 1.

Comparative example 1

The steps described in Example 1 were used to prepare the hierarchically porous MOFs material, except that in step 2), 50 mL of polystyrene dispersion with a solid content of 2 wt % was prepared.

Figure 6 shows the SEM image of the product obtained in Comparative Example 1. Since the mass ratio of ZIF-8 to polystyrene is 2:1, it is difficult to maintain a complete ZIF-8 skeleton structure after etching, resulting in its fragmentation.

Comparative example 2

The step described in Example 2 was used to prepare the hierarchically porous MOFs material, except that the temperature at the nozzle in step 4) was 160°C.

Figure 7 is the SEM image of the product obtained in Comparative Example 2. Due to the high temperature at the nozzle, only about 30% of the clusters formed after spray drying are spherical, and they are severely broken after etching.

Comparative example 3

The steps as described in Example 3 were used to prepare the hierarchically porous MOFs material, except that the particle size of polystyrene in step 2) was 800 nm.

Figure 8 shows the SEM image of the product obtained in Comparative Example 3. Since the particle size of the template agent used is too large, the clusters formed by spray drying are supported by the template agent, and MOFs will also be formed after etching. The collapse of the skeleton.

Comparative example 4

The step described in Example 4 was used to prepare the hierarchically porous MOFs material, the difference being that in step 3), the feed solution A and the feed solution B were directly mixed without ultrasonic treatment.

The agglomeration of the template agent is easily caused during the spray drying process, and the pore structure distribution of the obtained hierarchical porous MOFs material is not uniform.

Comparative example 5

The steps as described in Example 6 were used to prepare the hierarchically porous MOFs material, except that the etching temperature in step 5) was 200°C.

Due to the high temperature used in the etching process, the polystyrene template was removed and adhered to the surface of the hierarchically porous ZIF-8.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. All the implementation manners cannot be exhaustively listed here. All obvious changes or variations derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (13)

1. The preparation method of the hierarchical pore MOFs material capable of maintaining the complete framework is characterized by comprising the following steps of:

s1, dispersing MOFs material into a solvent, and marking as feed liquid A; the particle size of the MOFs material is 1-100nm;

s2, dispersing a template agent into a solvent, and marking as a feed liquid B; the particle size of the template agent is 20-600nm;

s3, mixing the feed liquid A and the feed liquid B to form a mixed dispersion; the mass ratio of the feed liquid A to the feed liquid B is 3:1-10:1, and ultrasonic treatment is performed for 4-6min when the feed liquid A and the feed liquid B are mixed;

s4, introducing the mixed dispersion obtained in the step S3 into a spray dryer for spray drying to obtain a mixed cluster body of MOFs material and template agent; the temperature of the nozzle in the spray drying process is 100-140 ℃;

s5, dissolving the mixed cluster body obtained in the step S4 in a liquid phase medium for etching, removing a template agent, and obtaining the hierarchical pore MOFs material through centrifugation, washing and drying; the etching reaction conditions are heating and stirring, the heating temperature is 25-100 ℃, and the reaction time is 0.5-10h.

2. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in the steps S1 and S2, the solvent is selected from one or more of the following substances: water, methanol, ethanol, N-dimethylformamide, toluene, tetrahydrofuran, ethylene glycol, cyclohexane.

3. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in the step S1, the particle size of the MOFs material is 5-50nm.

4. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in the step S1, the solid content of the feed liquid A is 1-10wt%.

5. The method for preparing the hierarchical porous MOFs material according to claim 4, wherein the steps of: in the step S1, the solid content of the feed liquid A is 2-5wt%.

6. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in step S2, the template agent is selected from one or more of the following substances: polystyrene, silicon dioxide, mesoporous zeolite, alumina, cetyltrimethylammonium bromide, dodecanoic acid, N-dimethyl octadecyl amine, and sodium 4-dodecyl benzoate.

7. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in the step S2, the particle size of the template agent is 50-500nm.

8. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in the step S2, the solid content of the feed liquid B is 1-8 wt%.

9. The method for preparing the hierarchical porous MOFs material according to claim 8, wherein the steps of: in the step S2, the solid content of the feed liquid B is 2-5wt%.

10. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in step S4, introducing the mixed dispersion into a spray dryer by a peristaltic pump;

in the step S4, the air speed of compressed air in the spray drying process is 300-800L/h;

in step S4, the input speed of the mixed dispersion in the spray drying process is 6-30mL/min.

11. The method for preparing the hierarchical porous MOFs material according to claim 10, wherein the steps of:

in the step S4, the air speed of compressed air in the spray drying process is 400-650L/h;

in step S4, the input speed of the mixed dispersion in the spray drying process is 10-23mL/min.

12. The method for preparing the hierarchical porous MOFs material according to claim 1, wherein the steps of: in step S5, the liquid medium is selected from one or more of the following: hydrofluoric acid, toluene, N-dimethylformamide, tetrahydrofuran and ethanol;

in step S5, the ratio of the mixed cluster body to the liquid phase medium is 1.5-6mg:1mL.

13. The method for preparing the hierarchical porous MOFs material according to claim 12, wherein:

in step S5, the ratio of the mixed cluster body to the liquid phase medium is 2-4.5mg:1mL.

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