CN113698620B

CN113698620B - Preparation method of carboxylic acid metal organic framework microspheres

Info

Publication number: CN113698620B
Application number: CN202111070590.1A
Authority: CN
Inventors: 李健生; 张雨婷; 齐俊文; 王超海; 孙秀云
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2021-09-13
Filing date: 2021-09-13
Publication date: 2023-07-04
Anticipated expiration: 2041-09-13
Also published as: CN113698620A

Abstract

The invention discloses a preparation method of carboxylic acid metal organic frame microspheres, which comprises the steps of adding high polymer resin into the preparation process of metal organic frame materials, reacting, and then obtaining millimeter-sized metal organic frame microspheres with single particle size distribution by a non-solvent induced phase separation method and a syringe pump extrusion process. The formed microbeads obtained by in-situ growth through a solvothermal method under a high-viscosity system can freely realize different metal-organic frame loads, avoid blocking of pore channels by a binder, are simple to prepare and easy to recycle, and have wide application prospects in the fields of catalysis, separation, adsorption and the like.

Description

Preparation method of carboxylic acid metal organic framework microspheres

Technical Field

The invention belongs to the technical field of metal organic framework materials, and particularly relates to a preparation method of carboxylic acid metal organic framework microspheres.

Background

Metal organic frameworks (Metal Organic Frameworks, MOFs) are a class of crystalline materials with periodic three-dimensional network frameworks formed from organic ligands and metal ions by a self-assembly process. Compared with the traditional porous material, MOFs have the advantages of extremely developed pore channel structure, ordered micropore structure, various framework structures, adjustable pore diameter and surface property, unsaturated metal active sites and the like. MOFs material as a novel functional molecular material has the characteristics of structural cuttability and easy functionalization which are incomparable with other materials, and therefore plays an important role in a plurality of fields such as catalysis, sensing, separation and the like.

Conventional synthesis methods typically result in MOF crystal powders with crystallite sizes ranging from nanometers to hundreds of microns. Polycrystalline powder materials are generally undesirable in industry because of many difficulties in handling, such as pressure drop, dust, clogging, wear, mass loss as the fluid flows through the packed bed, and challenges in transportation and handling. The moulding of MOFs into more valuable forms such as granules, gels or films (Y.Chen, X.Huang, S.Zhang, et al shaping of Metal-Organic Frameworks: from Fluid to Shaped Bodies and RobustF oams, J.Am.chem.Soc.,2016,138,10810-10813) has recently attracted considerable attention. In practical applications, especially in the field of gas phase transport and separation, how to form MOFs is an urgent problem to be solved.

At present, the molding method of MOFs materials mainly comprises pressure molding, bonding molding, embedding molding and the like. The MOFs powder is bonded into aggregates with larger bulk density through the action of high pressure, so that the storage and use volume space of the MOFs powder is greatly reduced, and the problem of difficult recovery is solved (BardiyaValizadeh, tuN.Nguyen, kyriakos C.Stylianou.shape engineering of metal-organic frameworks [ J ]. Polyhdron, 2018,145:1-15 ]). However. Excessive pressure can cause the inherently unstable MOFs backbone to transform to an amorphous state, resulting in collapse of the pore structure and loss of the unique properties of MOFs. The bonding molding is to mold MOFs particles under lower pressure by adding a certain polymer organic solvent or binder on the basis of pressure molding. Compared with high-pressure molding, the lower molding pressure can effectively avoid collapse and transformation of the framework structure, and molded particles with different shapes can be obtained according to the use requirements. However, blockage and coverage of the MOFs pore structure and active metal sites by binders is unavoidable and can severely impact its performance. On the other hand, the embedding formation method represented by spray drying and electrospinning cannot avoid blocking of the pore structure by the organic polymer chain (D.Lozano-Castel, D.Cazolla-Amor, S.A. Linares-Solano, et al, activated Carbon monoliths for methane storage: influence ofbinder [ J ]. Carbon,2002,40 (15): 2817-2825.). And the complex forming process and the low utilization rate of material efficiency of the material form a barrier for practical popularization and application.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention aims to provide a simple and convenient preparation method of carboxylic acid metal organic frame microspheres, and the formed microspheres obtained through solvothermal in-situ growth under a high-viscosity system can freely realize different metal organic frame loads, avoid blocking of a pore canal by a binder, are simple to prepare and easy to recycle, and have wide application prospects in the fields of catalysis, separation, adsorption and the like.

In order to achieve the technical purpose of the invention, the invention adopts the following technical scheme:

the invention relates to a preparation method of carboxylic acid metal organic frame microspheres, which adopts a one-step method to add macromolecule resin into the preparation process of carboxylic acid metal organic frame materials, and then applies a non-solvent to phase separation method in the field of membrane separation to the molding of the carboxylic acid metal organic frame microspheres after the reaction; millimeter-sized metal organic framework microspheres with single particle size distribution can be obtained through an injection pump extrusion process; the MOFs microsphere with controllable content can be obtained by adjusting the proportion of carboxylic acid ligand and corresponding metal precursor in the system.

The preparation method of the carboxylic acid metal organic framework microsphere comprises the following steps:

1) Dissolving high polymer resin and pore-forming agent PVP in N, N-Dimethylformamide (DMF) at 50-90 ℃ to prepare solution A;

2) Adding an organic carboxylic acid ligand into the solution A, stirring and dissolving to obtain a solution B;

3) Adding the solution B into the DMF solution of the metal precursor, and uniformly stirring to obtain a solution C;

4) Placing the solution C into a polytetrafluoroethylene high-pressure reaction kettle for solvothermal reaction, and growing MOFs in the process to obtain a solution D;

5) And extruding the solution D into a gelatinizing bath, carrying out split-phase gelatinization, and airing to obtain the metal organic framework microspheres.

Further, the mass fraction of the polymer resin in the solution A is 10% -24%, and the mass ratio of the polymer resin to the PVP is 2:1-8:1.

Further, the polymer resin is selected from polyacrylonitrile PAN or polyether sulfone PES.

Further, the mass ratio of the organic carboxylic acid ligand to the polymer resin is 1:1-1:20, wherein the organic carboxylic acid ligand is selected from terephthalic acid or trimesic acid.

Further, the mass ratio of the metal precursor to the polymer resin is 1:10-3:2, and the metal precursor is selected from zirconium tetrachloride, copper nitrate trihydrate, manganese acetate tetrahydrate or ferric trichloride hexahydrate.

Further, the thermal reaction condition is 80-220 ℃.

Further, the split-phase gelation extrusion speed is 0.5 mL/min-1.0 mL/min.

The beneficial effects of the invention are as follows:

1) The polymer resin is added into the preparation of the carboxylic MOFs, and the complex processes of one-step blending, bonding molding and the like are replaced, so that the operation is simple, the cost is low, and the equipment requirement is simple and convenient;

2) After the reaction, the particle size distribution of the spherical polymer-based precursor extruded by the injection pump is extremely narrow, the sphericity is high, the process is simple and controllable, and the industrial expansion production is easy;

3) The controllable preparation of the formed microspheres with different MOFs content can be realized by adjusting the proportion of the polymer resin to the carboxylic acid ligand and the metal precursor.

Drawings

FIG. 1 is a cross-sectional and partially enlarged scanning electron microscope view of the molded metal organic frame material prepared in example 1;

FIG. 2 is an X-ray diffraction pattern of the shaped metal-organic framework materials prepared in examples 1, 3, 4 and 5;

FIG. 3 is a graph of thermal analysis of the molded metal organic framework material prepared in example 1.

Detailed Description

The following description of the present invention will be made more complete and clear in view of the detailed description of the invention, which is to be taken in conjunction with the accompanying drawings that illustrate only some, but not all, of the embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

The embodiment particularly provides a preparation method of carboxylic acid metal organic framework microspheres, which comprises the following steps:

1) 2g PAN and 0.3g PVP were accurately weighed into a conical flask, 13mLN, N-dimethylformamide was added and mechanically stirred at 60℃until dissolved.

2) 1g of terephthalic acid was added and stirring was continued until the solution was uniform.

3) 1.5g of manganese acetate tetrahydrate is weighed and dissolved in 5mL of DMF, and then the solution in the step 2) is added and stirred uniformly.

4) Transferring the mixed solution obtained in the step 3) into a 50mL polytetrafluoroethylene reaction kettle, and placing the mixed solution in a 150 ℃ oven for reaction for 12 hours.

5) After the reaction kettle is cooled to room temperature, 5mL of the solution after the reaction in the step 4) is taken by a syringe and placed on a syringe pump, the speed of the syringe pump is regulated to be 0.7 mL/min, and liquid drops are extruded to 500mL of deionized water right below the needle of the syringe for split-phase gelation.

6) And taking out the millimeter-sized spherical beads after 12 hours, and airing at room temperature to obtain the formed Mn-BDC microspheres.

Example 2

1) 2g PAN and 0.3g PVP were accurately weighed, placed in an Erlenmeyer flask, 13mLN, N-dimethylformamide was added, and mechanically stirred at 60℃until dissolved.

2) 1.5g of terephthalic acid was added and stirring was continued until it was dissolved uniformly.

3) 2.25g of manganese acetate tetrahydrate is weighed and dissolved in 5mL of DMF, and then the solution in the step 2) is added and stirred uniformly.

Example 3

1) 2g PES and 0.3g PVP were accurately weighed, placed in an Erlenmeyer flask, 8mLN, N-dimethylformamide was added, and the mixture was mechanically stirred at 60℃until dissolved.

2) 0.4g of trimesic acid is added, and stirring is continued until the solution is uniform.

3) 0.42g of copper nitrate trihydrate is weighed and dissolved in 4mL of DMF and added to the solution of step 2) and stirred well.

4) Transferring the mixed solution obtained in the step 3) into a 50mL polytetrafluoroethylene reaction kettle, and placing the mixed solution in an oven at 80 ℃ to react for 24 hours.

6) And taking out the millimeter-sized ball after 12 hours, and airing at room temperature to obtain the formed Cu-BTC microsphere.

Example 4

2) 0.52g of terephthalic acid was added and stirring was continued until it was dissolved uniformly.

3) After 0.73g of zirconium tetrachloride was dissolved in 4mL of DMF, the solution of step 2) was added and stirred well.

4) Transferring the mixed solution obtained in the step 3) into a 50mL polytetrafluoroethylene reaction kettle, and placing the mixed solution in a 120 ℃ oven for reaction for 24 hours.

6) And taking out the millimeter-sized ball after 12 hours, and airing at room temperature to obtain the formed UIO-66 microsphere.

Example 5

2) 0.6g of terephthalic acid was added and stirring was continued until the solution was uniform.

3) 0.97g of ferric trichloride hexahydrate is weighed and dissolved in 5mL of DMF, and then the solution in the step 2) is added and stirred uniformly.

4) Transferring the mixed solution obtained in the step 3) into a 50mL polytetrafluoroethylene reaction kettle, and placing the mixed solution in a 100 ℃ oven for reaction for 12 hours.

6) And taking out the millimeter-sized ball after 12 hours, and airing at room temperature to obtain the formed MIL-88B microsphere.

As shown in fig. 1 to 3, fig. 1 shows that the molded metal organic frame material prepared in example 1 has obvious finger holes below the leather layer, and a large amount of MOFs particles are accumulated in the partial graph; FIG. 2 shows that the X-ray diffraction pattern of the resulting shaped metal-organic framework material is consistent with the X-ray diffraction peak positions of Mn-BDC, cu-BTC, HKUST-1 and MIL-88B, illustrating successful preparation of the shaped metal-organic framework material; fig. 3 shows a graph of thermal analysis of a shaped metal organic framework material.

Comparative example 1

This comparative example is substantially the same as example 1 except that: PVDF (polyvinylidene fluoride) is adopted as the polymer resin, but PVDF molecular chains are broken under high temperature and high pressure for a long time, and the obtained material cannot be balled.

Comparative example 2

This comparative example is substantially the same as example 5 except that: 2.5g of ferric trichloride hexahydrate is added, and the addition of excessive metal precursor containing a large amount of crystal water leads to phase separation of the whole system, so that the obtained material cannot be formed into balls.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The preparation method of the carboxylic acid metal organic framework microsphere is characterized by comprising the following steps of:

1) Dissolving high polymer resin and pore-forming agent PVP in N, N-dimethylformamide at 50-90 ℃ to prepare solution A; the mass fraction of the polymer resin in the solution A is 10% -24%, the mass ratio of the polymer resin to PVP is 2:1-8:1, and the polymer resin is selected from polyacrylonitrile PAN;

2) Adding an organic carboxylic acid ligand into the solution A, stirring and dissolving to obtain a solution B; the mass ratio of the organic carboxylic acid ligand to the high polymer resin is 1:1-1:20; the organic carboxylic acid ligand is selected from terephthalic acid or trimesic acid;

3) Adding the solution B into the DMF solution of the metal precursor, and uniformly stirring to obtain a solution C; the mass ratio of the metal precursor to the high polymer resin is 1:10-3:2; the metal precursor is selected from zirconium tetrachloride, copper nitrate trihydrate, manganese acetate tetrahydrate or ferric trichloride hexahydrate;

4) Placing the solution C into a polytetrafluoroethylene high-pressure reaction kettle, and performing thermal reaction to obtain a solution D: