An ultra-microporous zinc-based MOF material, a preparation method thereof and application thereof in ammonia gas adsorption
By preparing ultraporous zinc-based MOF materials, the energy-intensive and material instability problems of existing ammonia capture technologies have been solved, achieving efficient ammonia adsorption and stability, making them suitable for industrial-scale applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG CARBON LANGUAGE NEW MATERIAL CO LTD
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-05
AI Technical Summary
Existing ammonia capture technologies, such as wet scrubbing and catalytic reduction, are energy-intensive and generate waste. Traditional porous materials have limited ammonia capacity, and the high reactivity and corrosiveness of ammonia lead to structural instability in MOF materials.
The ultramicroporous zinc-based MOF material is formed by the coordination self-assembly of Zn2+ ions with squaric acid ligands and triazole ligands, constructing a three-dimensional periodic network structure. The pore size matches the dynamic diameter of ammonia molecules, forming strong interactions and improving stability and adsorption efficiency.
At room temperature, the mass adsorption capacity of ammonia is 2.3 mmol/g, and the volume adsorption capacity is as high as 4.8 mmol/cm3. The framework structure remains intact after being soaked in water for 7 days. It is low in cost and suitable for industrial-scale applications.
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Figure CN122145820A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of crystalline materials technology, and specifically relates to an ultramicroporous zinc-based MOF material, its preparation method, and its application in ammonia adsorption. Background Technology
[0002] Ammonia is widely considered one of the most viable media for hydrogen storage and distribution. As a renewable fuel, it can be produced on a large scale and at low cost, and burned in fuel cells to produce water and nitrogen as byproducts. However, any practical application requires several prerequisites, including the development of a safe and high-capacity storage medium, an efficient cracking process, and an effective ammonia leak capture and removal system. Current ammonia capture technologies, such as wet scrubbing and catalytic reduction, are energy-intensive and generate waste. Gas adsorption technology based on porous materials has attracted widespread attention due to its low energy consumption, ease of control, low equipment investment, and high capture efficiency.
[0003] Various traditional adsorbent materials have been used for the capture and storage of ammonia, but their capacities are often limited. Metal-organic frameworks (MOFs) are a new class of solid porous materials, consisting of a three-dimensional network structure formed by metal ions and organic ligands linked by coordination bonds. Compared with traditional porous materials such as zeolites, molecular sieves, and carbon materials, these materials have advantages such as large specific surface area, high porosity, and easily tunable pore structure and performance, showing broad application prospects in gas adsorption. The presence of acidic functional groups and open metal sites in MOF materials can significantly improve the adsorption capacity of ammonia, attracting increasing attention in ammonia adsorption. Nevertheless, due to the high reactivity and corrosiveness of ammonia, many carboxylate MOFs can hardly maintain their structural integrity under alkaline conditions, undergoing irreversible structural changes over time, leading to framework degradation. Therefore, developing stable MOF adsorbents and exploring their ammonia adsorption performance is of great research significance. Summary of the Invention
[0004] The purpose of this invention is to provide an ultramicroporous zinc-based MOF material, its preparation method, and its application in ammonia adsorption. This material exhibits excellent ammonia adsorption performance.
[0005] This invention is achieved through the following technical solution: This invention first provides an ultramicroporous zinc-based MOF material, which is made from Zn 2+ The ions, along with squaric acid ligands and triazole ligands, assemble through coordination to form an ultramicroporous zinc-based metal-organic framework material with a three-dimensional periodic network structure, wherein Zn... 2+The ions exhibit two coordination modes: six-coordinate octahedral and four-coordinate tetrahedral. The chemical formula of this material is C4H2N3O2Zn, and the molecular formula is [Zn2(C4O4)(C2H2N3)2], where C4O4... 2- It is a squaric acid ligand, C2H2N3 - It is a triazole ligand.
[0006] Preferably, the zinc-based MOF material has an orthorhombic crystal system with space group I. mma The unit cell parameters are: a = 7.2663(3)Å, b = 9.6193(4)Å, c = 16.8260(6)Å, α=β=γ=90 o .
[0007] Preferred, a Zn 2+ The ion coordinates with each of the two squaric acids, each providing one oxygen atom, and with each of the four triazole ligands providing one nitrogen atom, forming a six-coordinate octahedral coordination mode; another Zn 2+ The ion coordinates with each of the two squaric acids, each providing an oxygen atom, and with each of the two triazole ligands, each providing a nitrogen atom, forming a tetrahedral coordination mode.
[0008] Preferably, in the zinc-based MOF material, the six-coordinated octahedral building units are interconnected to form one-dimensional chain-like building units.
[0009] Preferably, the one-dimensional chain-like structures are interconnected by tetragonal units of tetraligands distributed in six directions, forming a 3D MOF structure with petal-like features.
[0010] Preferably, in the 3D MOF structure, there is a one-dimensional rhomboid channel along the a-axis direction, with a diameter of 2.6 Å × 4.6 Å.
[0011] This invention also provides a method for preparing ultramicroporous zinc-based MOF materials, comprising the following steps: Under sealed conditions, a microporous zinc-based MOF material was obtained by solvothermal reaction of ZnC2O4·2H2O, squaric acid (H2C4O4), and triazole (C2H3N3) in a mixed solution of water (H2O).
[0012] Preferably, the molar ratio of ZnC2O4·2H2O, squaric acid (H2C4O4), and triazole (C2H3N3) is 1:2:10.
[0013] Preferably, the temperature of the solvothermal reaction is 170-190°C, and the reaction time is 48-80 hours.
[0014] The present invention also provides the application of the aforementioned microporous zinc-based MOF material in ammonia adsorption.
[0015] Beneficial effects of the present invention This invention provides an ultramicroporous zinc-based MOF material, its preparation method, and its application in ammonia adsorption. Utilizing inexpensive zinc oxalate, squaric acid, and triazole, this invention successfully constructed a MOF material with a pore size (2.6 Å × 4.6 Å) matching the dynamic diameter of ammonia molecules and rich in N / O sites. Because transition metals can form strong coordination bonds with both oxygen (hard base) and nitrogen (soft base), this MOF material exhibits good stability, maintaining the integrity of its framework structure even after immersion in water for 7 days. The matched pore size and high density of N / O sites lead to strong interactions between the MOF material's framework and ammonia guest molecules, resulting in a mass adsorption capacity of 2.3 mmol / g and a volumetric adsorption capacity as high as 4.8 mmol / cm³ for NH₃ at 1.0 bar and room temperature. 3 It is approximately 60% of the volumetric adsorption capacity of ammonia by the well-known Mg-MOF-74 (7.96 mmol / cm³). 3 (1.0 bar and room temperature). High stability and low raw material or synthesis costs are beneficial for the mass production and application of MOF adsorbents on an industrial scale. This invention not only provides an ammonia adsorption material with potential applications, but also provides exploratory experience for the design and synthesis of novel stable MOF materials for ammonia capture applications. Attached Figure Description
[0016] Figure 1 The diagram shows the coordination mode of mononuclear Zn ions in the metal-organic framework material obtained in Example 1. Figure 2 This is a schematic diagram of the structure of a one-dimensional chain formed by octahedral units in the metal-organic framework material obtained in Example 1; Figure 3 This is a three-dimensional structural diagram of the metal-organic framework material obtained in Example 1; Figure 4 The pore size diagram is shown for the metal-organic framework material obtained in Example 1. Figure 5 The powder diffraction patterns of the metal-organic framework material obtained in Example 1 are based on single-crystal data simulation, and are shown for the freshly synthesized sample and the sample after soaking in water for 7 days. Figure 6 The graph shows the thermal stability analysis of the metal-organic framework material obtained in Example 1. Figure 7 The graph shows the ammonia adsorption curve of the metal-organic framework material obtained in Example 1 at 298K. Detailed Implementation
[0017] This invention first provides an ultramicroporous zinc-based MOF material, which is made from Zn 2+ The ions, along with squaric acid ligands and triazole ligands, assemble through coordination to form an ultramicroporous zinc-based metal-organic framework material with a three-dimensional periodic network structure, wherein Zn... 2+ The ion exists in two coordination modes: six-coordinate octahedral and four-coordinate tetrahedral; one Zn 2+ The ion coordinates with each of the two squaric acids, each providing one oxygen atom, and with each of the four triazole ligands providing one nitrogen atom, forming a six-coordinate octahedral coordination mode; another Zn 2+ The ion coordinates with each of the two squaric acids, each providing an oxygen atom, and with each of the two triazole ligands, each providing a nitrogen atom, forming a four-coordinate tetrahedral coordination mode. In the zinc-based MOF material, the six-coordinate octahedral building units are interconnected to form one-dimensional chain-like building units. Between these one-dimensional chain-like buildings, each chain is interconnected with the other chains through tetrahedral units distributed in six directions, forming a 3D MOF structure with petal-like features.
[0018] According to the present invention, the chemical formula of the material is C4H2N3O2Zn, and the molecular formula is [Zn2(C4O4)(C2H2N3)2], wherein C4O4 2- It is a squaric acid ligand, C2H2N3 - It is a triazole ligand.
[0019] According to the present invention, the crystal structure of the zinc-based MOF material belongs to the orthorhombic crystal system, and the space group is I. mma The unit cell parameters are: a = 7.2663(3)Å, b = 9.6193(4)Å, c = 16.8260(6)Å, α=β=γ=90 o In the 3D MOF structure, there is a one-dimensional rhomboid channel along the a-axis, with a diameter of 2.6 Å × 4.6 Å.
[0020] This invention also provides a method for preparing ultramicroporous zinc-based MOF materials, comprising the following steps: Under sealed conditions, ZnC₂O₄·2H₂O, squaric acid (H₂C₄O₄), and triazole (C₂H₃N₃) are reacted in a mixed solution of water (H₂O) via a solvothermal reaction. The preferred temperature of the solvothermal reaction is 170-190°C, more preferably 180°C, and the preferred reaction time is 48-80 hours, more preferably 72 hours. After the reaction is completed and cooled to room temperature, the resulting solid particles are filtered and collected, and then washed with methanol to obtain colorless, transparent, blocky crystals, i.e., ultraporous zinc-based MOF material. The preferred molar ratio of ZnC₂O₄·2H₂O, squaric acid (H₂C₄O₄), and triazole (C₂H₃N₃) is 1:2:10.
[0021] According to the present invention, the zinc-based metal-organic framework material has good stability and can still maintain the integrity of the framework structure after being soaked in water for 7 days.
[0022] The present invention also provides the application of the aforementioned microporous zinc-based MOF material in ammonia adsorption.
[0023] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.
[0024] Example 1 Commercially purchased ligands squaric acid (0.1 mmol) and triazole (0.5 mmol) and inorganic salt ZnC4O4·2H2O (0.05 mmol) were weighed and placed in a 7 mL glass vial. 2.5 mL of water was added, and the vial was sealed and placed in an ultrasonicator for sonication at room temperature for 5 minutes. After sealing, the vial was placed in an oven at 180 °C for 72 hours. After the reaction was complete, the oven was turned off, and the vial was cooled to room temperature. The resulting solid particles were collected by filtration, washed with methanol, and observed under a microscope to yield colorless, transparent, blocky crystals [Zn2(C4O4)(C2H2N3)2] (yield: 68%, based on H2C4O4 ligand).
[0025] The crystal [Zn2(C4O4)(C2H2N3)2] prepared in Example 1 was characterized as follows: (1) Determination of crystal structure: A single crystal of suitable size was selected, and X-ray diffraction data were collected at ~300 K using monochromatic Mo / Kα radiation (λ=0.071073 nm) on a CrysAlisPro 1.171.42.95a (Rigaku OD, 2023). Data reconstruction was performed using CrysAlisPro 1.171.42.95a (Rigaku OD, 2023). The crystal structure was resolved using the Olex software package via a direct method, followed by refinement using full-matrix least squares. In the final round, anisotropic refinement was performed on non-hydrogen atoms. The positions of hydrogen atoms were obtained through theoretical hydrogenation, with the isotropic displacement parameter of the hydrogen atoms set to 1.2 × U of the connecting atoms. eq Crystallographic data are shown in Table 1.
[0026] Table 1. Crystallographic data of metal-organic framework materials
[0027] The structural diagram of the zinc-based metal-organic framework material prepared in Example 1 is shown below. Figure 1-4 As shown.
[0028] Figure 1This is a coordination pattern diagram of mononuclear Zn ions in the metal-organic framework material obtained in Example 1. In this metal-organic framework material, Zn... 2+ The ion employs two different coordination modes: a six-coordinate octahedral coordination mode and a four-coordinate tetrahedral coordination mode. Zn 2+ The ion coordinates with one oxygen atom from each of the two squaric acids and one nitrogen atom from each of the four triazole ligands, forming a six-coordinate octahedral coordination mode. Additionally, Zn... 2+ The ion also coordinates to one oxygen atom from each of the two squaric acids and one nitrogen atom from each of the two triazole ligands, forming a tetrahedral coordination mode. The six-coordinate octahedral units interconnect to form a one-dimensional chain-like building block, see […]. Figure 2 .
[0029] Figure 3 This is a three-dimensional structural diagram of the ligands in the metal-organic framework material obtained in Example 1. Each chain is interconnected via four-coordinate tetrahedral units distributed in six directions, forming a 3D MOF framework structure with petal-like features. In this framework structure, one-dimensional rhombic channels exist along the a-axis, with a pore size of 2.6 Å × 4.6 Å, belonging to a typical ultraporous structure. See [link to documentation]. Figure 4 .
[0030] (2) Characterization of materials: The material obtained in Example 1 was characterized by powder X-ray diffraction, see [see details]. Figure 5 The powder X-ray diffraction peaks of the newly synthesized sample are in excellent agreement with those simulated by the single-crystal structure. Therefore, the obtained material is a MOF material exhibited by a single-crystal structure, and the prepared sample is a pure phase. To investigate the thermal stability of this MOF material, thermogravimetric analysis was performed on the newly synthesized sample at 25-700℃. Figure 6 It can be observed that the framework of the metal-organic framework material can be stable up to nearly 500°C. After 500°C, the framework of the MOF material collapses.
[0031] (3) Water stability of the material: The crystal sample obtained in Example 1 was immersed in water, and its powder X-ray diffraction pattern was measured daily. Figure 5 As shown, after seven days, the powder X-ray diffraction peaks of the sample soaked in water remained almost identical to those of the newly synthesized sample. This indicates that the metal-organic framework material has excellent water stability.
[0032] (4) Gas adsorption test: Figure 7The figure shows the adsorption isotherm of ammonia by the metal-organic framework material obtained in Example 1 at 298 K. As can be seen from the figure, at 298 K and 1.0 bar, the mass adsorption capacity of this metal-organic framework material for ammonia is 50.6 cm³ / g (2.3 mmol / g), and the volume adsorption capacity is as high as 4.8 mmol / cm³. 3 It is approximately 60% of the volumetric adsorption capacity of ammonia by the well-known Mg-MOF-74 (7.96 mmol / cm³). 3 (1.0 bar and room temperature).
[0033] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.
Claims
1. A microporous zinc-based MOF material, characterized in that, This material is made from Zn 2+ The ions, along with squaric acid ligands and triazole ligands, assemble through coordination to form an ultramicroporous zinc-based metal-organic framework material with a three-dimensional periodic network structure, wherein Zn... 2+ The ions exhibit two coordination modes: six-coordinate octahedral and four-coordinate tetrahedral. The chemical formula of this material is C4H2N3O2Zn, and the molecular formula is [Zn2(C4O4)(C2H2N3)2], where C4O4... 2- It is a squaric acid ligand, C2H2N3 - It is a triazole ligand.
2. The ultraporous zinc-based MOF material according to claim 1, characterized in that, The zinc-based MOF material has an orthorhombic crystal system and a space group of I. mma The unit cell parameters are: a = 7.2663(3)Å, b = 9.6193(4)Å, c = 16.8260(6)Å, α=β=γ=90 o .
3. The ultraporous zinc-based MOF material according to claim 1, characterized in that, A type of Zn 2+ The ion coordinates with each of the two squaric acids, each providing one oxygen atom, and with each of the four triazole ligands providing one nitrogen atom, forming a six-coordinate octahedral coordination mode; another Zn 2+ The ion coordinates with one oxygen atom from each of the two squaric acids and one nitrogen atom from each of the two triazole ligands, forming a tetrahedral coordination mode.
4. The ultramicroporous zinc-based MOF material according to claim 1, characterized in that, In the zinc-based MOF material, six-coordinated octahedral building units are interconnected to form one-dimensional chain-like building units.
5. The ultraporous zinc-based MOF material according to claim 4, characterized in that, Between the aforementioned one-dimensional chain-like structures, each chain is interconnected by tetragonal units of tetraligands distributed in six directions, forming a 3D MOF structure with petal-like features.
6. The ultramicroporous zinc-based MOF material according to claim 1, characterized in that, In the 3D MOF structure, there is a one-dimensional rhomboid channel along the a-axis direction, with a diameter of 2.6 Å × 4.6 Å.
7. The method for preparing an ultramicroporous zinc-based MOF material according to claim 1, characterized in that, Includes the following steps: Under sealed conditions, a microporous zinc-based MOF material was obtained by solvothermal reaction of ZnC2O4·2H2O, squaric acid and triazole in a mixed solution of water.
8. The method for preparing an ultramicroporous zinc-based MOF material according to claim 7, characterized in that, The molar ratio of ZnC2O4·2H2O, squaric acid, and triazole is 1:2:
10.
9. The method for preparing an ultraporous zinc-based MOF material according to claim 7, characterized in that, The solvothermal reaction is carried out at a temperature of 170-190℃ for 48-80 hours.
10. The application of the ultramicroporous zinc-based MOF material according to claim 1 in ammonia adsorption.