A method for preparing zirconium-based metal-organic framework materials and their applications

Abstract

This application discloses a method for preparing zirconium-based metal-organic framework materials, belonging to the field of adsorbents. Addressing the problem in existing technologies where "metal-organic framework materials used as water adsorbents suffer from difficulty in precisely controlling water adsorption behavior and poor water adsorption cycle stability," the technical solution of this application involves adding a quantitative amount of Zr-TCPB-Br2 to solutions of ligands H2PDC, H2BPYDC, and H2PhenDC, and conducting a solvothermal reaction. This accurately embeds a series of auxiliary ligands into specific nodes within the Zr-TCPB-Br2 framework, yielding a series of zirconium-based metal-organic framework materials. The zirconium-based metal-organic framework materials prepared by this invention can improve the water adsorption cycle stability of zirconium-based metal-organic framework materials, with the adsorption amount remaining almost constant during three water adsorption processes. It can also reduce the S-type adsorption "inflection point" of the aforementioned materials to relative humidity levels of 44%, 50%, 49%, 48%, 39%, and 38% RH, respectively, making them particularly suitable for water adsorption-related conditions such as capturing water in low-humidity air and controlling indoor humidity.

Description

Technical Field

[0001] This invention relates to a method for preparing zirconium-based metal-organic framework materials and their applications, belonging to the field of adsorbents. Background Technology

[0002] Developing porous adsorbent materials for water adsorption is crucial, as they are widely used in applications such as natural gas dehydration, air capture, indoor humidity control, adsorption-driven heat pumps, and cooling. In water adsorption applications, the material's water adsorption capacity and water adsorption cycle stability are two critical factors. However, current common adsorbent materials, such as molecular sieves and silica gel, generally suffer from low water adsorption capacity, high regeneration energy consumption, and difficulties in functionalization and precise control. Therefore, developing materials that can precisely control water adsorption behavior and achieve stable water adsorption cycles is extremely important, suitable for various water adsorption conditions with specific requirements.

[0003] Based on this, metal-organic frameworks (MOFs) are porous crystalline materials with periodic network structures formed by the self-assembly of inorganic metal ions and organic ligands through coordination bonds. Due to their precise structural design and functionalization modifications, MOFs hold great promise for applications in water adsorption. In particular, aluminum-based, chromium-based, and zirconium-based MOFs exhibit very stable structures, which are expected to advance the practical application of water adsorption. Although the framework of aluminum-based and chromium-based MOFs can resist the capillary forces acting on the inner walls of the material pores during desorption, and the amount of water adsorbed does not decrease in water adsorption cycle tests, demonstrating stable water adsorption cycles, the bond energies in the coordination bonds formed between aluminum and chromium ions and oxygen in carboxylic acid ligands are very high, making it difficult to obtain single crystals of aluminum-based and chromium-based MOFs. This prevents the precise resolution of their structures at the molecular scale using single-crystal X-ray diffraction. Conversely, zirconium-based MOFs offer a rich variety of structures and are relatively easy to obtain as single crystals, facilitating the exploration of the structure-property relationship between MOF structure and water adsorption performance, and promoting the design of high-performance MOFs for water adsorption applications. However, currently only a few zirconium-based MOFs exhibit stable water adsorption cycles. Therefore, developing methods for preparing zirconium-based MOFs that precisely regulate water adsorption behavior and enhance water adsorption cycle stability is a crucial step in promoting the practical application of this material, and also a highly challenging technical problem. Summary of the Invention

[0004] To address the problem in existing technologies that "metal-organic framework materials are difficult to precisely control in terms of water adsorption behavior and have poor stability in water adsorption cycles when used as water adsorbents," a method for preparing zirconium-based metal-organic framework materials and their applications are proposed.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a method for preparing zirconium-based metal-organic framework materials, using at least one of 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid as auxiliary ligands; using 1'4'-dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene and zirconium tetrachloride as framework raw materials, and modifying and embedding the auxiliary ligands by a solvothermal method to prepare zirconium-based MOFs;

[0006] 1'4'-Dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene and zirconium tetrachloride form a Zr-TCPB-Br2 framework structure;

[0007] In the Zr-TCPB-Br2-based structure, the Zr6 clusters are 6-connected nodes with 6 empty sites; among all the empty nodes of the Zr6 clusters, the distance between the empty nodes of adjacent Zr6 clusters has at least three different lengths.

[0008] Based on the chain lengths of 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid, length matching was performed, and 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid were respectively embedded into the empty nodes of the Zr6 cluster;

[0009] The insertion of auxiliary ligands increases the number of connections in zirconium-based metal clusters, and the inserted auxiliary ligands contain Lewis basic N sites.

[0010] In an optimized manner, the above-mentioned method for preparing zirconium-based metal-organic framework materials is based on the fact that the Zr6 clusters in the Zr-TCPB-Br2 structure are 6-connected nodes with 6 vacant sites, and the distances between the vacant sites of adjacent Zr6 clusters are 6.6 Å, 11.1 Å, and 11.9 Å, respectively.

[0011] Optimally, the preparation method of the above-mentioned zirconium-based metal-organic framework material adopts the post-modified ligand intercalation method, which refers to dispersing the synthesized Zr-TCPB-Br2 into a solution of auxiliary ligands and carrying out a solvothermal reaction.

[0012] In an optimized manner, in the post-modified ligand intercalation method of the above-mentioned zirconium-based metal-organic framework material preparation method, the solvent for the framework raw material is a mixed solution of N,N-diethylformamide and acetic acid; and the solvent for the auxiliary ligand is N,N-diethylformamide (DMF).

[0013] The above-mentioned method for preparing zirconium-based metal-organic framework materials is optimized.

[0014] According to mass ratio, when 2,5-pyrazine dicarboxylic acid is used as an auxiliary ligand, the mass ratio of the Zr-TCPB-Br2 skeleton structure formed by 1'4'-dibromo-2,3,5,6-tetra(4-carboxybenzene)benzene and zirconium tetrachloride to 2,5-pyrazine dicarboxylic acid is 20:(3~5).

[0015] According to mass ratio, when 2,2'-bipyridine-5,5'-dicarboxylic acid is used as an auxiliary ligand, the mass ratio of Zr-TCPB-Br2 skeleton structure to 2,2'-bipyridine-5,5'-dicarboxylic acid is 20:(4-8) or 20:(9-15);

[0016] According to mass ratio, when 2,5-pyrazine dicarboxylic acid and 2,2'-bipyridine-5,5'-dicarboxylic acid are used as auxiliary ligands, the mass ratio of the Zr-TCPB-Br2 skeleton structure to 2,5-pyrazine dicarboxylic acid and 2,2'-bipyridine-5,5'-dicarboxylic acid is 20:(3~5):(4~8);

[0017] According to mass ratio, when 1,10-phenanthroline-3,8-dicarboxylic acid is used as an auxiliary ligand, the mass ratio of Zr-TCPB-Br2 skeleton structure to 1,10-phenanthroline-3,8-dicarboxylic acid is 20:(6-9).

[0018] According to mass ratio, when 2,5-pyrazine dicarboxylic acid and 1,10-phenanthroline-3,8-dicarboxylic acid are used as auxiliary ligands, the mass ratio of the Zr-TCPB-Br2 skeleton structure to 2,5-pyrazine dicarboxylic acid and 1,10-phenanthroline-3,8-dicarboxylic acid is 20:(3~5):(6~9).

[0019] In an optimized method for preparing the above-mentioned zirconium-based metal-organic framework material, the ratio of the embedded ligand to DMF in the preparation of the embedded ligand solution is 1:(50-100) by mass.

[0020] In an optimized manner, in the above-mentioned method for preparing zirconium-based metal-organic framework materials, the reaction temperature of the solvothermal synthesis in the post-modified ligand intercalation method is 80°C to 120°C, and the reaction time of the solvothermal synthesis is 4 hours to 70 hours.

[0021] In an optimized manner, the preparation method of the above-mentioned zirconium-based metal-organic framework material involves filtration and collection of the filter cake after the solvothermal reaction is completed.

[0022] The filter cake was washed with DMF and acetone and then dried to obtain zirconium-based MOFs.

[0023] In the optimized method for preparing the zirconium-based metal-organic framework material, the washing process is carried out using DMF and acetone, respectively, and the total amount of solvent used in the washing process to the solvent used in the synthesis of the zirconium-based metal-organic framework material is 1-10:20 by mass.

[0024] The drying time is 8h to 20h, and the drying temperature is 100℃ to 150℃.

[0025] An application of a zirconium-based metal-organic framework material, wherein the zirconium-based metal-organic framework material is used in water adsorption-related applications such as capturing water in the air and regulating indoor humidity.

[0026] The beneficial effects of this application are as follows:

[0027] The zirconium-based metal-organic framework material prepared by the method in this application can not only precisely control the water adsorption behavior, but also enhance the stability of water adsorption cycles, that is, after three cycles of water adsorption, its water adsorption capacity is still maintained.

[0028] Meanwhile, the embedding of different single ligands and mixed ligands can cause the S-type adsorption "inflection point" of the corresponding material to shift to different degrees in the low humidity range.

[0029] Regarding water adsorption, the zirconium-based metal-organic framework material prepared by this invention has a high water adsorption capacity and is stable in cycles, and its S-type adsorption "inflection point" is located at a relative humidity of 38-50%RH.

[0030] The adsorbent based on the zirconium-based metal-organic framework material prepared in this invention can be used to capture water in low-humidity air and regulate indoor humidity. Attached Figure Description

[0031] Figure 1 The crystal structure diagram of Zr-TCPB-Br2 prepared in Comparative Example 1;

[0032] Figure 2 This is a crystal structure diagram of Zr-TCPB-Br2-PDC prepared in Example 1 of this application;

[0033] Figure 3 The crystal structure diagram of Zr-TCPB-Br2-BPYDC-L prepared in Example 2 of this application is shown.

[0034] Figure 4 The crystal structure diagram of Zr-TCPB-Br2-BPYDC-H prepared in Example 3 of this application is shown.

[0035] Figure 5 The crystal structure diagram of Zr-TCPB-Br2-PDC-BPYDC prepared in Example 4 of this application is shown.

[0036] Figure 6 This is a crystal structure diagram of Zr-TCPB-Br2-PhenDC prepared in Example 5 of this application;

[0037] Figure 7 The crystal structure diagram of Zr-TCPB-Br2-PDC-PhenDC prepared in Example 6 of this application is shown.

[0038] Figure 8 Comparative Example 1 and Examples 1-6 of this application show the theoretical, experimental, and X-ray powder diffraction (PXRD) spectra of Zr-TCPB-Br2, Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, and Zr-TCPB-Br2-PDC-PhenDC.

[0039] Figure 9 The water adsorption isotherms at room temperature of Zr-TCPB-Br2, Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, Zr-TCPB-Br2-PDC-PhenDC, Zr-TCPB-Br2, Zr-TCPB-Br2-BDC, Zr-TCPB-Br2-BPDC, and Zr-TCPB-Br2-BDC-BPDC prepared in Comparative Example 1 and Examples 1 to 6 of the present invention are shown.

[0040] Figure 10 Comparative diagram of the three-stage water adsorption isotherms of Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, and Zr-TCPB-Br2-PDC-PhenDC prepared in Comparative Example 1 and Examples 1-6. Detailed Implementation

[0041] This application provides a method for preparing zirconium-based metal-organic framework materials and their applications, which precisely regulate water adsorption behavior and enhance the stability of water adsorption cycles. The method for preparing the zirconium-based metal-organic framework materials includes...

[0042] Zirconium-based metal-organic framework (Zr-TCPB-Br2) was prepared using 1'4'-dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene (H4TCPB-Br2) and zirconium tetrachloride as raw materials. The Zr-TCPB-Br2 structure features 6-connected Zr6 clusters with 6 vacant sites, and the distances between the vacant nodes of adjacent Zr6 clusters are 6.6, 11.1, and 11.1, respectively. Considering that the chain lengths of 2,5-pyrazine dicarboxylic acid (H2PDC), 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC), and 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) are 6.6, 11.1, and... The distance between the vacant nodes of the Zr6 cluster in Zr-TCPB-Br2 is very close. After modification and insertion of auxiliary ligands using a solvothermal method, the above ligands are accurately embedded into specific vacant nodes of the Zr6 cluster based on size matching.

[0043] On the one hand, the insertion of auxiliary ligands increases the number of connections in the zirconium-based metal cluster. This increased number of connections can resist the capillary forces exerted by water molecules on the inner walls of the material's pores during desorption, resulting in stable water adsorption cycles. On the other hand, the aforementioned inserted ligands contain Lewis basic N sites, which provide adsorption sites for water molecules through hydrogen bonding. This enhances the hydrophilicity of the framework structure's pores, causing the S-type adsorption "inflection point" to shift to varying degrees within a low humidity range, enabling water adsorption applications in low humidity environments.

[0044] In this application, the method for preparing zirconium-based metal-organic framework material Zr-TCPB-Br2 using 1'4'-dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene (H4TCPB-Br2) and zirconium tetrachloride as raw materials can be prepared using the method described in Comparative Example 1 below.

[0045] In a solvothermal reaction, 1'4'-dibromo-2,3,5,6-tetra(4-carboxybenzene)benzene (H4TCPB-Br2) and zirconium tetrachloride were ultrasonically dispersed in a mixed solution of N,N-diethylformamide (DEF) and acetic acid, and the reaction was carried out to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2. The ligands 2,5-pyrazine dicarboxylic acid (H2PDC), 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC), and 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) were ultrasonically dispersed in a solution of N,N-dimethylformamide (DMF).

[0046] When preparing the solution containing the intercalating auxiliary ligand, the ratio of the intercalated auxiliary ligand to DMF is 1:50-100 by mass to obtain solution AF.

[0047] In this solution, solution A contains 2,5-pyrazine dicarboxylic acid (H2PDC) dissolved in DMF; solution B contains a small amount of 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) dissolved in DMF; solution C contains a large amount of 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) dissolved in DMF; solution D contains both 2,5-pyrazine dicarboxylic acid (H2PDC) and 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) dissolved in DMF; solution E contains 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) dissolved in DMF; and solution F contains both 2,5-pyrazine dicarboxylic acid (H2PDC) and 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) dissolved in DMF.

[0048] In this embodiment, the synthesized Zr-TCPB-Br2 was dispersed into a solution of an auxiliary ligand using a post-modified ligand intercalation method, followed by a solvothermal reaction. In the post-modified ligand intercalation method, the solvothermal synthesis reaction temperature was 80℃~120℃, and the reaction time was 4h~70h.

[0049] After the solvothermal reaction was completed, the mixture was filtered and the filter cake was collected. The filter cake was washed with DMF and acetone respectively and then dried to obtain zirconium-based MOFs.

[0050] The washing process was performed using DMF and acetone, with the total mass ratio of the solvent used in the washing process to the solvent used in the synthesis of the zirconium-based metal-organic framework material being 1-(10:20). The drying process lasted for 8 to 20 hours at a temperature of 100°C to 150°C.

[0051] The zirconium-based metal-organic framework material prepared by this invention can precisely regulate water adsorption behavior and enhance the stability of water adsorption cycle. Since the Zr6 cluster in the Zr-TCPB-Br2 structure is a 6-connected node with 6 vacant sites, it provides the possibility for the intercalated auxiliary ligand to be intercalated into the vacant sites of the Zr6 cluster. Furthermore, the distance between the vacant nodes of adjacent Zr6 clusters is very close to the chain length of 2,5-pyrazine dicarboxylic acid (H2PDC), 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC), and 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC), which makes the distance between the vacant nodes of adjacent Zr6 clusters match the chain length of the auxiliary ligand. The insertion of auxiliary ligands increases the number of connections in the zirconium-based metal clusters. This increased number of connections can resist the capillary forces exerted by water molecules on the inner walls of the material's pores during desorption, thus improving the material's water adsorption cycle stability. On the other hand, the selected ligands contain Lewis basic N sites, which helps to enhance the hydrophilicity of the pores in the framework structure, causing the S-type adsorption "inflection point" to shift to different degrees in the low humidity range, making it suitable for water adsorption applications in different low humidity ranges.

[0052] This invention also provides applications for the preparation of zirconium-based MOFs materials that precisely regulate water adsorption behavior and enhance water adsorption cycle stability. These applications involve using the prepared zirconium-based MOFs for water adsorption. For example, they can be used as adsorbent components to capture water from the air under low humidity conditions and for controlling indoor humidity.

[0053] The technical solution of this application will be further explained below with specific examples.

[0054] Comparative Example 1:

[0055] 0.8 g of 1'4'-dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene (H4TCPB-Br2) and 1.2 g of zirconium tetrachloride were ultrasonically dispersed in a mixture of 200 mL of N,N-diethylformamide (DEF) and 40 mL of acetic acid. The mixture was allowed to stand at 120 °C for 24 h for a solvothermal reaction. After the reaction was completed, the mixture was filtered and the filter cake was collected. The filter cake was washed with 200 mL of N,N-dimethylformamide (DMF) and 500 mL of acetone, respectively. The washed filter cake was then dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2.

[0056] Example 1:

[0057] 0.04 g of 2,5-pyrazine dicarboxylic acid (H2PDC) was ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution A; 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution A and allowed to stand at 80 °C for 5 h for a solvothermal reaction; after the reaction was completed, the mixture was filtered and the filter cake was collected; the filter cake was washed with 100 mL of DMF and 300 mL of acetone, respectively, and the washed filter cake was dried at 120 °C for 10 h to obtain zirconium-based metal-organic framework material Zr-TCPB-Br2-PDC.

[0058] Example 2:

[0059] 0.06 g of 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) was ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution B; 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution B and allowed to stand at 80 °C for 8 h for a solvothermal reaction; after the reaction was completed, the mixture was filtered and the filter cake was collected; the filter cake was washed with 200 mL of DMF and 400 mL of acetone, respectively, and the washed filter cake was dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2-BPYDC-L.

[0060] Example 3:

[0061] 0.14 g of 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) was ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution C; 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution C and allowed to stand at 80 °C for 70 h for a solvothermal reaction; after the reaction was completed, the mixture was filtered and the filter cake was collected; the filter cake was washed with 400 mL of DMF and 500 mL of acetone, respectively, and the washed filter cake was dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2-BPYDC-H.

[0062] Example 4:

[0063] 0.06 g of 2,5-pyrazine dicarboxylic acid (H2PDC) and 0.06 g of 2,2'-bipyridine-5,5'-dicarboxylic acid (H2BPYDC) were ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution D. 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution D and allowed to stand at 80 °C for 24 h for a solvothermal reaction. After the reaction was completed, the mixture was filtered and the filter cake was collected. The filter cake was washed with 200 mL of DMF and 400 mL of acetone, respectively. The washed filter cake was dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2-PDC-BPYDC.

[0064] Example 5:

[0065] 0.06 g of 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) was ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution E; 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution E and allowed to stand at 80 °C for 10 h for a solvothermal reaction; after the reaction was completed, the mixture was filtered and the filter cake was collected; the filter cake was washed with 200 mL of DMF and 400 mL of acetone, respectively, and the washed filter cake was dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2-PDC-PhenDC.

[0066] Example 6:

[0067] 0.06 g of 2,5-pyrazine dicarboxylic acid (H2PDC) and 0.06 g of 1,10-phenanthroline-3,8-dicarboxylic acid (H2PhenDC) were ultrasonically dispersed in 20 mL of N,N-dimethylformamide (DMF) to obtain solution F. 0.2 g of Zr-TCPB-Br2 was ultrasonically dispersed in solution F and allowed to stand at 80 °C for 24 h for a solvothermal reaction. After the reaction was completed, the mixture was filtered and the filter cake was collected. The filter cake was washed with 300 mL of DMF and 500 mL of acetone, respectively, and then dried at 120 °C for 10 h to obtain the zirconium-based metal-organic framework material Zr-TCPB-Br2-PDC-PDCC-PhenDC.

[0068] Test example:

[0069] I. Single Crystal Structure Analysis

[0070] The single crystals of zirconium-based metal-organic framework materials prepared in Comparative Example 1 and Examples 1-6 were analyzed using a Bruker KappaAPEX II single crystal diffractometer to obtain their crystallographic data, which are shown in Tables 1 and 2.

[0071] Table 1. Crystallographic data of organic framework materials prepared in Comparative Example 1 and Examples 1-3

[0072]

[0073] Table 1 shows that the insertion of auxiliary ligands (2,5-pyrazine dicarboxylic acid, H2PDC; 2,2'-bipyridine-5,5'-dicarboxylic acid, H2BPYDC; 1,10-phenanthroline-3,8-dicarboxylic acid, H2PhenDC) does not affect the cell parameters of zirconium-based metal-organic framework materials, and the resulting crystals all belong to the cubic crystal system.

[0074] Figure 1-7These are the crystal structures of Zr-TCPB-Br2, Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, and Zr-TCPB-Br2-PDC-PhenDC. Figure 1-7 It is known that the ligands H2PDC, H2BPYDC, and H2PhenDC selectively embed at different sites without affecting the overall scaffold structure.

[0075] II. X-ray Powder Diffraction (PXRD) Analysis

[0076] The structures of the materials synthesized in Comparative Example 1 and Examples 1-6 were characterized using a STOE-STADIP X-ray powder diffractometer. The double diffraction angle range was 2-20°, and the test voltage and current were 40 kV and 40 mA, respectively. Cu-K α The radiation has a wavelength of 0.15406 nm.

[0077] Table 2 Crystallographic data of organic framework materials prepared in Examples 4-6

[0078]

[0079] Figure 8 The PXRD spectra of Zr-TCPB-Br2, Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, and Zr-TCPB-Br2-PDC-PhenDC prepared in Comparative Examples 1 and Examples 1-6 are shown. Figure 8 As can be seen, the PXRD spectra of the six zirconium-based metal-organic framework materials synthesized in Comparative Examples 1 and Examples 1-6 are identical, indicating that the structures of these six samples are consistent with those of Comparative Example 1. Furthermore, the diffraction peak positions of the six samples synthesized in Comparative Examples 1 and Examples 1-6 are the same as the peak positions of the PXRD spectra simulated from single-crystal structures, indicating that high-purity materials from Comparative Examples 1 and Examples 1-6 were synthesized.

[0080] III. Water Adsorption Isotherm Test

[0081] The water adsorption isotherms of Zr-TCPB-Br2, Zr-TCPB-Br2-PDC, Zr-TCPB-Br2-BPYDC-L, Zr-TCPB-Br2-BPYDC-H, Zr-TCPB-Br2-PDC-BPYDC, Zr-TCPB-Br2-PhenDC, Zr-TCPB-Br2-PDC-PhenDC, and Zr-TCPB-Br2-BDC-BPDC prepared in Comparative Example 1 and Examples 1-3 were tested using a Micromeritics 3Flex vapor adsorption analyzer. The results are as follows: Figure 9 As shown, during the first water adsorption process, Zr-TCPB-Br2 achieved a water adsorption capacity as high as 0.60 g / g at 90% RH. However, during the second and third water adsorption processes, the water adsorption capacity decreased to 0.49 g / g and 0.41 g / g, respectively, representing losses of 18% and 32%. (Comparison) Figure 8 It can be seen that after three water adsorptions, the characteristic peak intensities at 2.7° and 5.5° of Zr-TCPB-Br2 decreased and broadened significantly, indicating that the framework structure of Zr-TCPB-Br2 partially collapsed and was destroyed.

[0082] When embedding a single auxiliary ligand H2PDC, considering the proximity of the H2PDC chain length to the distances between nodes in the small square channels of the Zr-TCPB-Br2 structure, H2PDC is precisely embedded between the short-node Zr6 clusters, constructing Zr-TCPB-Br2-PDC. When embedding single auxiliary ligands H2BPYDC and H2PhenDC, considering the proximity of the H2BPYDC and H2PhenDC chain lengths to the distances between nodes in the large square channels of the Zr-TCPB-Br2 structure, Zr-TCPB-Br2-BPYDC-L and Zr-TCPB-Br2-PhenDC are constructed. Since H2PDC, H2BPYDC, and H2PhenDC are embedded on the nodes in the small and large square channels of the Zr-TCPB-Br2 structure, respectively, their embedding positions do not interfere with each other. Therefore, when the mixed ligands H2PDC and H2BPYDC, or H2PDC and H2PhenDC, are simultaneously embedded in the node positions left in the small and large square channels of the Zr-TCPB-Br2 structure, respectively, Zr-TCPB-Br2-PDC-BPYDC and Zr-TCPB-Br2-PDC-PhenDC can be constructed. Compared with H2PhenDC, H2BPYDC has better flexibility; that is, the two pyridine rings in H2BPYDC can rotate and twist, but the phenanthroline in H2PhenDC is coplanar and cannot rotate or twist. When the concentration of the auxiliary ligand H2BPYDC is increased and the solvothermal reaction time is prolonged, H2BPYDC can not only be embedded in the node positions left in the large square channels of the Zr-TCPB-Br2 structure, but also in the node positions left in the small square channels of the Zr-TCPB-Br2 structure in a diagonal manner, thus constructing Zr-TCPB-Br2-BPYDC-H. Compared to the first water adsorption capacity, the second and third water adsorption capacities of the six zirconium-based metal-organic framework materials with ligand inlay remained unchanged at 90% RH. Furthermore, comparing the PXRD spectra after three water adsorption cycles revealed no significant changes, indicating that the material structure remained intact. These data demonstrate that the inlay of auxiliary ligands can improve the water adsorption cycle stability of zirconium-based metal-organic framework materials.

[0083] Furthermore, compared to Zr-TCPB-Br2, whose S-type adsorption "inflection point" is at a relative humidity of 56% RH, the intercalation of H2PDC, H2BPYDC, and H2PhenDC can reduce the S-type adsorption "inflection point" of the aforementioned materials to relative humidity of 44%, 50%, 49%, 48%, 39%, and 38% RH, respectively. This makes it particularly suitable for water adsorption-related conditions such as capturing water in low-humidity air and regulating indoor humidity.

[0084] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A method for preparing a zirconium-based metal-organic framework material, characterized in that: Zirconium-based MOFs were prepared by using at least one of 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid as auxiliary ligands, and using 1'4'-dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene and zirconium tetrachloride as skeletal raw materials, followed by modification and insertion of auxiliary ligands via a solvothermal method. 1'4'-Dibromo-2,3,5,6-tetra(4-carboxyphenyl)benzene and zirconium tetrachloride form a Zr-TCPB-Br2 framework structure; The method of post-modified ligand intercalation is adopted, which refers to dispersing the synthesized Zr-TCPB-Br2 into a solution of auxiliary ligands and carrying out a solvothermal reaction. In the Zr-TCPB-Br2-based structure, the Zr6 clusters are 6-connected nodes with 6 empty sites; among all the empty nodes of the Zr6 clusters, the distance between the empty nodes of adjacent Zr6 clusters has at least three different lengths. Based on the chain lengths of 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid, length matching was performed, and 2,5-pyrazine dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 1,10-phenanthroline-3,8-dicarboxylic acid were respectively embedded into the empty nodes of the Zr6 cluster.

2. The method for preparing zirconium-based metal-organic framework materials according to claim 1, characterized in that: In the Zr-TCPB-Br2-based structure, the Zr6 clusters are 6-connected nodes with 6 empty sites, and the distances between the empty sites of adjacent Zr6 clusters are 6.6 Å, 11.1 Å, and 11.9 Å, respectively.

3. The method for preparing zirconium-based metal-organic framework materials according to claim 1, characterized in that: The solvent for the skeletal raw material is a mixed solution of N,N-diethylformamide and acetic acid; the solvent for the auxiliary ligand is a solution of N,N-dimethylformamide.

4. The method for preparing zirconium-based metal-organic framework materials according to claim 1, characterized in that: According to mass ratio, when 2,5-pyrazine dicarboxylic acid is used as an auxiliary ligand, the mass ratio of the Zr-TCPB-Br2 skeleton structure formed by 1'4'-dibromo-2,3,5,6-tetra(4-carboxybenzene)benzene and zirconium tetrachloride to 2,5-pyrazine dicarboxylic acid is 20:(3~5). According to mass ratio, when 2,2'-bipyridine-5,5'-dicarboxylic acid is used as an auxiliary ligand, the mass ratio of Zr-TCPB-Br2 skeleton structure to 2,2'-bipyridine-5,5'-dicarboxylic acid is 20:(4-8) or 20:(9-15); According to mass ratio, when 2,5-pyrazine dicarboxylic acid and 2,2'-bipyridine-5,5'-dicarboxylic acid are used as auxiliary ligands, the mass ratio of the Zr-TCPB-Br2 skeleton structure to 2,5-pyrazine dicarboxylic acid and 2,2'-bipyridine-5,5'-dicarboxylic acid is 20:(3~5):(4~8); According to mass ratio, when 1,10-phenanthroline-3,8-dicarboxylic acid is used as an auxiliary ligand, the mass ratio of Zr-TCPB-Br2 skeleton structure to 1,10-phenanthroline-3,8-dicarboxylic acid is 20:(6~9). According to mass ratio, when 2,5-pyrazine dicarboxylic acid and 1,10-phenanthroline-3,8-dicarboxylic acid are used as auxiliary ligands, the mass ratio of the Zr-TCPB-Br2 skeleton structure to 2,5-pyrazine dicarboxylic acid and 1,10-phenanthroline-3,8-dicarboxylic acid is 20:(3~5):(6~9).

5. The method for preparing zirconium-based metal-organic framework materials according to claim 1, characterized in that: In the post-modified ligand intercalation method, the reaction temperature for solvothermal synthesis is 80℃ to 120℃, and the reaction time is 4 hours to 70 hours.

6. The application of the zirconium-based metal-organic framework material prepared by any one of claims 1-5, characterized in that: The application involves using the zirconium-based metal-organic framework material to capture water from the air and regulate indoor humidity.

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