Preparation of pyrazole-3,4,5-tricarboxylate ligand heteronuclear metal organic framework materials and gas adsorption separation applications

Abstract

This invention discloses the preparation and gas adsorption separation application of pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials, comprising the following steps: 1) Weighing CuCl2·2H2O, Ba(NO3)2, and 1H-pyrazole-3,4,5-tricarboxylic acid as raw materials; 2) Placing the raw materials in a polytetrafluoroethylene-lined reactor, adding distilled water, and adjusting the pH to 2-4 with malonic acid; 3) Sealing the reactor and heating the reaction, raising the temperature from room temperature to 80-120℃ over 0-12 hours, holding the temperature for 70-75 hours, and then lowering it to room temperature over another 0-12 hours; 4) Collecting the product, washing, and vacuum drying to obtain the chemical formula [Cu2Ba(HL)2(H2O)3]. n The crystal is a pyrazole-3,4,5-tricarboxylic acid. By combining the multi-site coordination advantages, heterometallic node construction advantages, and pore functionalization control advantages of pyrazole-3,4,5-tricarboxylic acid, a stable framework structure can be constructed while simultaneously adjusting pore size, optimizing pore wall polarity, and constructing local adsorption sites, thereby enhancing the material's application potential in SF6 capture and separation, and C2 gas adsorption and storage.

Description

Technical Field

[0001] This invention relates to the field of metal-organic framework materials, and more particularly to the preparation and gas adsorption and separation application of a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material. Background Technology

[0002] Metal-organic frameworks (MOFs) exhibit superior performance in gas recognition, adsorption, and mass transfer compared to traditional porous materials due to the high designability of their metal nodes and organic linkers, their well-defined crystal structures, ultra-high specific surface areas, and adjustable pore sizes and internal chemical environments. However, current technologies for MOF applications in gas adsorption and separation still have several shortcomings: the limited types of coordination sites for single organic ligands and the limited number of functional sites in the pores make it difficult to achieve synergistic control of pore size, polarity, and adsorption sites, thus limiting the optimization of material performance; the lack of nitrogen-containing functional sites within the constructed framework pores hinders the fine control of the pore chemical environment and makes it difficult to enhance the interaction between the framework and specific gas molecules; and frameworks with single metal ions as nodes suffer from insufficient flexibility in structural construction due to the limited metal coordination characteristics, resulting in limited means of adjusting the pore microenvironment and making it impossible to introduce diverse adsorption sites into the same framework, which is detrimental to the synergistic control of host-guest interactions.

[0003] Currently, existing technologies still lack organic ligands and their corresponding metal-organic framework materials that simultaneously possess heterometallic nodes, nitrogen-containing sites, and polycarboxylic acid coordination sites, and can achieve synergistic regulation of framework structure construction and pore microenvironment. This makes it impossible to meet the practical application needs of such materials in the field of gas adsorption and separation. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a method for the preparation and gas adsorption and separation application of pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials. This method combines the advantages of multi-site coordination, heterometallic node construction, and pore functionalization of pyrazole-3,4,5-tricarboxylic acid. While achieving stable framework structure construction, it also takes into account pore size adjustment, pore wall polarity optimization, and local adsorption site construction, thereby enhancing the application potential of the material in SF6 capture and separation, and C2 gas adsorption and storage.

[0005] This invention provides a method for preparing a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material, comprising the following steps:

[0006] 1) Weigh out CuCl2·2H2O, Ba(NO3)2 and 1H-pyrazole-3,4,5-tricarboxylic acid as raw materials;

[0007] 2) Place the above raw materials in a polytetrafluoroethylene-lined reactor, add distilled water, and adjust the pH to 2-4 with malonic acid;

[0008] 3) Seal the above reaction vessel and heat it to react. Raise the temperature from room temperature to 80-120℃ in 0-12h, keep it constant for 70-75h, and then lower it to room temperature in 0-12h.

[0009] 4) Collect the product, wash it, and vacuum dry it to obtain the chemical formula [Cu2Ba(HL)2(H2O)3]. n Crystals, wherein L is pyrazole-3,4,5-tricarboxylic acid.

[0010] Furthermore, by mass: CuCl2·2H2O is 210 mg, Ba(NO3)2 is 160 mg, 1H-pyrazole-3,4,5-tricarboxylic acid is 30 mg, and distilled water is 14 mL.

[0011] Furthermore, in step 4), the washing process uses deionized water and methanol; the vacuum drying temperature is 70-90℃, and the time is 25-35 min.

[0012] In addition, the present invention also provides a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material prepared by the above-mentioned method for preparing pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials.

[0013] In addition, the present invention also provides an application of the pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material as described above in gas adsorption and separation.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. Material synthesis and structural construction:

[0016] Based on pyrazole-3,4,5-tricarboxylic acid ligand-based heteronuclear metal-organic framework materials and their preparation methods, synergistic optimization was achieved from three levels: ligand design, metal node construction, and pore functionalization. By introducing transition metals for coordination with 6p metals, the synthetic approach of constructing frameworks using heterometals as nodes was expanded, and the resulting material formed a heterometallic microporous framework [Cu2Ba(HL)2(H2O)3] with rhombic one-dimensional channels. n The material exhibits well-defined pore geometry and an adjustable pore wall chemical environment, which facilitates the size sieving of different gas molecules and the regulation of host-guest interactions. The resulting material possesses microporous characteristics with a pore size of approximately 7.3 Å, indicating that the constructed framework has a well-defined pore structure.

[0017] 2. Gas adsorption and separation performance:

[0018] 1) The material constructed in this invention exhibits a volumetric adsorption capacity of 81.97 cm³ for CO₂ at 298 K and 273 K, respectively. 3 / cm 3 and 90.60cm 3 / cm 3 This indicates that the material has good CO2 adsorption performance.

[0019] 2) The material of this invention exhibits excellent performance in C2 gas adsorption. At 298 K, the volume adsorption capacities for C2H2, C2H4, and C2H6 are 87.47 cm³, respectively. 3 / cm 3 75.56cm 3 / cm 3 and 70.51cm 3 / cm 3 This indicates that the material has application potential in the adsorption and storage of acetylene / ethylene / ethane.

[0020] 3) The material of this invention also exhibits good adsorption and separation performance in SF6 / N2 separation. Under conditions of 298 K and 1 bar, the volume adsorption capacities for SF6 and N2 are 59.53 cm³ and 59.53 cm³, respectively. 3 / cm 3 and 14.03cm 3 / cm 3 The corresponding IAST selectivity of SF6 / N2 is 308, indicating that the material can preferentially adsorb SF6 and is suitable for SF6 capture and separation.

[0021] 3. Application Value:

[0022] 1) CO2 capture and separation:

[0023] The material contains polar sites within its pores that can interact with CO2, enabling selective adsorption of CO2 during flue gas, industrial exhaust gas, or natural gas purification processes, thereby reducing carbon emissions and improving gas purity.

[0024] 2) Adsorption and storage of C2 gases such as acetylene, ethylene, and ethane:

[0025] This material exhibits strong adsorption capacity for C2 gas, enabling high-density gas storage under milder conditions, thereby reducing the equipment and energy consumption requirements of traditional high-pressure or low-temperature storage methods. The material helps improve gas storage safety, reduce leakage risks, and increase gas storage efficiency per unit volume. This material has potential for promoting energy conservation, improving raw material utilization efficiency, and advancing the safe operation of related chemical processes.

[0026] 3) SF6 capture and SF6 / N2 separation:

[0027] Due to its strong adsorption capacity and high separation selectivity for SF6, it can be used for the separation and recovery of SF6 / N2 mixed gas during the operation and maintenance of electrical equipment, and has the potential value of reducing greenhouse gas emissions and promoting the recycling of SF6.

[0028] 4) Gas purification and resource recovery:

[0029] This material combines a microporous structure with an adjustable pore wall environment, making it suitable as an adsorbent for the enrichment, purification, and recovery of specific gas components, thereby improving the utilization rate of raw materials and the added value of products in industrial processes.

[0030] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0031] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 In the example, (a) is [Cu2Ba(HL)2(H2O)3]. n The coordination model diagram, (b) is [Cu2Ba(HL)2(H2O)3] n A three-dimensional spatial structure diagram;

[0033] Figure 2 [Cu2Ba(HL)2(H2O)3] n Aperture distribution diagram;

[0034] Figure 3 [Cu2Ba(HL)2(H2O)3] n PXRD test image;

[0035] Figure 4 [Cu2Ba(HL)2(H2O)3] n Thermogravimetric analysis diagram;

[0036] Figure 5 [Cu2Ba(HL)2(H2O)3] n Schematic diagram of SF6 and N2 adsorption isotherms at 298K;

[0037] Figure 6 [Cu2Ba(HL)2(H2O)3] n A schematic diagram of the adsorption isotherms of CO2, C2H2, C2H4, and C2H6 at 298K;

[0038] Figure 7 [Cu2Ba(HL)2(H2O)3] n Schematic diagrams of CO2 adsorption isotherms at 298K and 273K;

[0039] Figure 8 [Cu2Ba(HL)2(H2O)3] n A schematic diagram of the heat of CO2 adsorption;

[0040] Figure 9 [Cu2Ba(HL)2(H2O)3] n A schematic diagram of IAST selectivity for SF6 / N2 mixed gas; Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] Please refer to Figures 1-9 The present invention provides a method for preparing a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material, comprising the following steps:

[0044] 1) Weigh out CuCl2·2H2O (copper chloride dihydrate), Ba(NO3)2 (barium nitrate) and 1H-pyrazole-3,4,5-tricarboxylic acid as raw materials;

[0045] 2) Place the above raw materials in a polytetrafluoroethylene-lined reactor, add distilled water, and adjust the pH to 2-4 with malonic acid;

[0046] 3) Seal the above reaction vessel and heat it to react. Raise the temperature from room temperature to 80-120℃ in 0-12h, keep it constant for 70-75h, and then lower it to room temperature in 0-12h.

[0047] 4) Collect the product, wash it, and vacuum dry it to obtain the chemical formula [Cu2Ba(HL)2(H2O)3]. n Crystals of (pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials), where L is pyrazole-3,4,5-tricarboxylic acid.

[0048] By mass: CuCl2·2H2O is 210 mg, Ba(NO3)2 is 160 mg, 1H-pyrazole-3,4,5-tricarboxylic acid is 30 mg, and distilled water is 14 mL.

[0049] In step 4), the washing process uses deionized water and methanol; the vacuum drying temperature is 70-90℃ and the time is 25-35 min.

[0050] In addition, the present invention also provides a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material prepared by the above-mentioned method for preparing pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials.

[0051] In addition, the present invention also provides an application of the pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material as described above in gas adsorption and separation.

[0052] In this embodiment, based on pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials and their preparation methods, synergistic optimization was achieved from three levels: ligand design, metal node construction, and pore functionalization. By introducing transition metals for coordination with 6p metals, the synthetic approach of constructing frameworks using heterometals as nodes was expanded, and the resulting material formed a heterometallic microporous framework [Cu2Ba(HL)2(H2O)3] with rhombic one-dimensional channels. n The material exhibits well-defined pore geometry and an adjustable pore wall chemical environment, which facilitates the size sieving of different gas molecules and the regulation of host-guest interactions. The resulting material possesses microporous characteristics with a pore size of approximately 7.3 Å, indicating that the constructed framework has a well-defined pore structure.

[0053] The material constructed in this embodiment achieved a volumetric adsorption capacity of 81.97 cm³ for CO₂ at 298 K and 273 K, respectively. 3 / cm 3 and 90.60cm 3 / cm 3 This indicates that the material has good CO2 adsorption performance; the material also exhibits good performance in C2 gas adsorption, with volumetric adsorption capacities of 87.47 cm³ for C2H2, C2H4, and C2H6 at 298 K. 3 / cm 3 75.56cm 3 / cm 3 and 70.51cm 3 / cm 3This indicates that the material has application potential in the adsorption and storage of acetylene / ethylene / ethane; the material also exhibits good adsorption and separation performance in SF6 / N2 separation, with volumetric adsorption capacities of 59.53 cm³ for SF6 and N2 at 298 K and 1 bar. 3 / cm 3 and 14.03cm 3 / cm 3 The corresponding IAST selectivity of SF6 / N2 is 308, indicating that the material can preferentially adsorb SF6 and is suitable for SF6 capture and separation.

[0054] In this embodiment, the material contains polar sites within its pores that can interact with CO2, enabling selective adsorption of CO2 during flue gas, industrial tail gas, or natural gas purification processes. This reduces carbon emissions and improves gas purity. The material exhibits strong adsorption capacity for C2 gas, allowing for high-density gas storage under milder conditions, thus reducing the equipment and energy consumption requirements of traditional high-pressure or low-temperature storage methods. The material helps improve gas storage safety, reduces leakage risks, and increases gas storage efficiency per unit volume. This material has potential for promoting energy conservation, improving raw material utilization efficiency, and driving the safe operation of related chemical processes. Its microporous structure and adjustable pore wall environment allow it to be used as an adsorbent for the enrichment, purification, and recovery of specific gas components, improving raw material utilization and product added value in industrial processes.

[0055] In this embodiment, due to its strong adsorption capacity and high separation selectivity for SF6, it can be used for the separation and recovery of SF6 / N2 mixed gas during the operation and maintenance of electrical equipment, and has the potential value of reducing greenhouse gas emissions and promoting the recycling of SF6.

[0056] Example 1

[0057] Weigh out 210 mg of CuCl2·2H2O, 160 mg of Ba(NO3)2, and 30 mg of 1H-pyrazole-3,4,5-tricarboxylic acid. Place these raw materials sequentially into a 25 mL polytetrafluoroethylene-lined high-temperature reactor. Add 14 mL of distilled water to the reactor using a pipette. Finally, add malonic acid to adjust the pH to 3. Seal the reactor and place it in an oven for heating. First, raise the temperature from room temperature to 120°C over 12 hours, then maintain the temperature at 120°C for 72 hours, and finally lower it to room temperature over 12 hours. After the reaction is complete, collect the product. Wash the obtained product with deionized water and methanol, and then dry it in an 80°C vacuum drying oven for 30 minutes to obtain the target product. The chemical formula of the target product is [Cu2Ba(HL)2(H2O)3]. n The target product is a blue, transparent, rectangular blocky crystal with a yield of approximately 65% ​​(estimated based on L).

[0058] Example 2

[0059] The reaction temperature can be adjusted within the range of 80-120℃, and the reaction time can be extended to obtain larger crystals. Appropriately shortening the reaction time can yield high-quality single crystals with better crystallinity. There is no significant difference in the structure and properties of the products.

[0060] Example 3

[0061] By replacing Cu with other transition metals such as Co, Ni, and Zn, while keeping other raw materials and steps unchanged, the target material with the same structure can be obtained.

[0062] Example 4

[0063] By replacing Ba with other metals from the same group, such as Be, Mg, Ca, or Sr, while keeping other raw materials and steps unchanged, the target material with the same structure can be obtained.

[0064] Example 5

[0065] Using a mixed solvent system, methanol, acetonitrile, N,N-dimethylformamide, etc. are added as mixed solvents after the raw materials are mixed. By adjusting the ratio of these solvents to deionized water, the target material with the same structure can be obtained.

[0066] Example 6

[0067] By replacing malonic acid with other weak acids such as phthalic acid or terephthalic acid to adjust the solution pH, while keeping other raw materials and steps unchanged, the target material can be obtained.

[0068] Example 7

[0069] Other synthesis methods, such as solvent evaporation, diffusion, or ultrasound-assisted synthesis, can be used to prepare this series of crystals.

[0070] (1) Calculate the heat of adsorption (Q) based on the Werley equation. st ):

[0071]

[0072] Where P is pressure, N is adsorption amount, T is temperature, m and n are the number of terms required to fully describe the isotherm, and a i and b j These are empirical parameters.

[0073] (2) The adsorption isotherms of the same group of gases to be calculated were fitted using a two-point Langmuir model:

[0074]

[0075] Where q is the adsorption amount, qsat is the saturated adsorption amount, b is the Langmuir parameter, p is the volumetric gas phase pressure, and A and B represent two different points.

[0076] (3) Derive and calculate the IAST selectivity of the gas mixture, assuming that the ratio of the two gas mixtures is 50:50 (v / v%):

[0077]

[0078] Where, q i p represents the adsorption amount of component i. i Let be the partial pressure of component i.

[0079] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0080] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework materials, characterized in that, Includes the following steps: 1) Weigh out CuCl2·2H2O, Ba(NO3)2 and 1H-pyrazole-3,4,5-tricarboxylic acid as raw materials; 2) Place the above raw materials in a polytetrafluoroethylene-lined reactor, add distilled water, and adjust the pH to 2-4 with malonic acid; 3) Seal the above reaction vessel and heat it to react. Raise the temperature from room temperature to 80-120℃ in 0-12h, keep it constant for 70-75h, and then lower it to room temperature in 0-12h. 4) Collect the product, wash it, and vacuum dry it to obtain the chemical formula [Cu2Ba(HL)2(H2O)3]. n Crystals, wherein L is pyrazole-3,4,5-tricarboxylic acid.

2. The method for preparing the pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material according to claim 1, characterized in that, By mass: CuCl2·2H2O is 210 mg, Ba(NO3)2 is 160 mg, 1H-pyrazole-3,4,5-tricarboxylic acid is 30 mg, and distilled water is 14 mL.

3. The method for preparing the pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material according to claim 2, characterized in that, In step 4), the washing process uses deionized water and methanol; the vacuum drying temperature is 70-90℃ and the time is 25-35 min.

4. A pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material prepared by the preparation method of the pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material according to any one of claims 1-4.

5. The application of a pyrazole-3,4,5-tricarboxylic acid ligand heteronuclear metal-organic framework material as described in claim 3 in gas adsorption and separation.

Images