Ultra-microporous metal-organic framework materials, preparation thereof and application thereof for xenon-krypton separation

Abstract

The application discloses an ultramicroporous metal organic framework material, a preparation method thereof and a xenon / krypton separation application. 12 H 12 ] 2‑ The six-coordinated divalent metal cation M is coordinated with the four-tooth nitrogen-containing ligand L in the horizontal direction to form an infinitely extended two-dimensional network structure, is coordinated with two water molecules in the vertical direction to form a two-dimensional secondary structure unit, and finally is coordinated with the divalent inorganic anion [B 12 H 12 ](H2O)2, wherein L is a four-tooth nitrogen-containing ligand 1,1,2,2-tetrakis (pyridine-4-yl) ethylene, the metal cation M is one or more than two of Cu 2+ , Ni 2+ , Fe 2+ , Co 2+ , Zn 2+ .

Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, specifically to an ultramicroporous metal-organic framework material, its preparation method, and its application in xenon and krypton separation. Background Technology

[0002] Industrially, xenon and krypton feedstock gases mainly come from two sources: by-product mixtures from large-scale air separation units and waste gas from spent nuclear power plant fuel reprocessing. The xenon and krypton in these feedstock gases are fundamentally derived from the atmosphere. Xenon and krypton have significant applications in high-tech fields such as lighting, medical applications, and aerospace electric propulsion; achieving efficient separation of the two has both major economic and environmental implications. However, xenon and krypton have highly similar atomic sizes and physicochemical properties, and their concentrations in the air are extremely low (xenon is only about 0.087 ppmv, and krypton is only about 1.14 ppmv), making separation a persistent technical challenge in the gas separation field. Currently, a large amount of xenon-krypton mixtures in industry are not effectively purified, resulting in a serious waste of valuable rare gas resources. Cryogenic distillation is the mainstream technology for industrial xenon-krypton separation, utilizing the difference in their boiling points to achieve separation at low temperatures. However, this technology is complex, requires large equipment investments, consumes a lot of energy, and is mainly suitable for large-scale air separation units, limiting its application in low-concentration, high-radioactivity scenarios such as nuclear power plant waste gas. Therefore, there is an urgent need to develop new, efficient, and low-energy-consumption separation technologies. Physical adsorption is a relatively energy-efficient separation technology, the core of which lies in the development of high-performance porous adsorbents. However, existing traditional adsorbents are difficult to achieve efficient separation: traditional activated carbon has limited adsorption capacity, a wide and disordered pore size distribution, and a xenon / krypton separation selectivity of only 2-3, with severe co-adsorption; conventional zeolite molecular sieves have a xenon / krypton selectivity of only 4-6, low overall porosity, and an absolute xenon adsorption capacity generally below 1 mmol / g; the patent specification with publication number CN121155519A discloses the application of silver-modified AFX molecular sieve in xenon / krypton gas separation. Although the silver-modified molecular sieve has significantly better selectivity and capacity than traditional molecular sieves, it suffers from problems such as easy deactivation of active sites, poor operating stability, complex preparation process, and high cost for large-scale production, and cannot meet the separation needs of high-concentration and trace systems in all scenarios.

[0003] Metal-organic frameworks (MOFs) are a class of organic-inorganic hybrid materials with intramolecular pores, formed by the self-assembly of organic ligands and metal ions or clusters through coordination bonds. They possess advantages such as large specific surface area and finely tunable pore size and pore environment, showing potential application prospects in the field of gas adsorption and separation. However, existing MOF materials still face key bottlenecks restricting their industrial application: it is difficult to simultaneously achieve high adsorption capacity and high separation selectivity; they have poor hydrothermal and environmental tolerance, making it impossible to operate stably for a long time under complex industrial conditions such as humidity (Sep. Purif. Technol., 2020, 116514); and the synthesis conditions of some high-performance materials are harsh, making it difficult to achieve low-cost, large-scale, and stable production.

[0004] In summary, while existing cryogenic distillation technology and various porous adsorption materials have made some progress, core bottlenecks still need to be overcome. Xenon and krypton have highly similar physicochemical properties and complex industrial application conditions. Existing materials generally struggle to balance adsorption capacity, separation selectivity, and environmental stability, significantly limiting industrial application. The industry still lacks dedicated adsorption materials for xenon-krypton separation with excellent comprehensive performance. Therefore, developing novel MOF adsorbents that can achieve efficient xenon-krypton separation at room temperature and pressure, possess excellent hydrothermal and radiation stability, have simple synthesis processes, and are low in cost, is of significant practical importance for overcoming the technological barriers to rare gas purification and ensuring the safe and stable development of related fields. Summary of the Invention

[0005] To address the aforementioned technical problems and shortcomings in this field, the present invention provides an ultramicroporous metal-organic framework material, its preparation method, and its application in xenon-krypton separation.

[0006] The specific technical solution is as follows: In a first aspect, the present invention provides an ultraporous metal-organic framework material, comprising a two-dimensional network structure in which a six-coordinated divalent metal cation M coordinates with a tetradentate nitrogen-containing ligand L in the horizontal direction to form an infinitely extended network structure, and then coordinates with two water molecules in the vertical direction to form two-dimensional secondary structural units, and finally, a divalent inorganic anion [B 12 H 12 ] 2- By forming double hydrogen bonds with water molecules with a length of 2.8~3.0 Å, they are embedded between two-dimensional layers to form a complete ultraporous metal-organic framework material; The molecular formula of the ultramicroporous metal-organic framework material is ML(B) 12 H 12 (H₂O)₂, where L is the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene, and the metal cation M is Cu. 2+ Ni 2+ Fe 2+ Co 2+ Zn 2+ One or more of them.

[0007] Divalent inorganic anion [B 12 H 12 ] 2- It is a dodecylborate group, with the following structure: .

[0008] The ultramicroporous metal-organic framework material described in this invention can be synthesized using at least one of the well-known interfacial diffusion method, stirring method, solvothermal method, etc.

[0009] In a second aspect, the present invention provides a method for preparing the ultramicroporous metal-organic framework material described in the first aspect, comprising: preparing a precursor of a metal cation M and an inorganic anion [B... 12 H 12 ] 2- The precursor and the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene are mixed and reacted in a solvent to obtain the ultraporous metal-organic framework material.

[0010] In some preferred embodiments, the precursor of the metal cation M comprises a nitrate.

[0011] In some preferred embodiments, the inorganic anion [B 12 H 12 ] 2- The precursors include sodium salts.

[0012] In some preferred embodiments, the solvent includes methanol and water.

[0013] In some preferred embodiments, the reaction temperature is room temperature to 60 °C, for example, 50 °C.

[0014] In some preferred embodiments, the preparation method specifically includes: adding solution A, buffer solution and solution B sequentially to a container, and allowing the reaction to proceed to obtain the ultraporous metal-organic framework material; Solution A includes a precursor of metal cation M and inorganic anion [B]. 12 H 12 ] 2- The precursor and solvent water; The buffer solution comprises methanol and water; Solution B comprises the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene and the solvent methanol.

[0015] More preferably, the volume ratio of methanol to water in the buffer solution is 1:1.

[0016] In some preferred embodiments, the preparation method specifically includes: adding a methanol solution of the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene to the precursor of the metal cation M and the inorganic anion [B 12 H 12 ] 2- The ultraporous metal-organic framework material is obtained by reacting in a mixed aqueous solution of the precursor.

[0017] Thirdly, this invention provides the application of the ultramicroporous metal-organic framework material described in the first aspect for the adsorption of xenon gas. The ultramicroporous metal-organic framework material of this invention achieves a very high adsorption capacity for xenon gas (in a xenon / krypton mixed system) within a certain temperature range.

[0018] Fourthly, the present invention provides the application of the microporous metal-organic framework material described in the first aspect for the adsorption and separation of xenon and krypton. The microporous metal-organic framework material can selectively adsorb xenon. The microporous metal-organic framework material achieves a separation selectivity of 11.84 for a xenon and krypton mixture with a molar ratio of 20:80 at 298 K and 100 kPa.

[0019] Xenon and krypton have very small differences in physical properties such as atomic size, and both are present at low concentrations in exhaust gases. This necessitates that the adsorbent possess strong recognition sites for xenon to effectively exclude krypton and other gaseous components. Xenon also exhibits significantly high polarizability (40.44 × 10⁻⁶). -25 cm 3 Krypton is 24.84 × 10 -25 cm 3 Therefore, polarization sites can be introduced into the channels to achieve selective adsorption of xenon.

[0020] The invention relates to [B] 12 H 12 ] 2- The anionic ultraporous metal-organic framework not only has a large number of regularly arranged negatively charged [B] atoms distributed on its surface. 12 H 12 ] 2- The functional groups, these negatively charged anions, form a special electrostatic environment within the confined space of the ultra-microporous metal-organic framework material with the specific structure of the present invention. This environment allows for the selective recognition and adsorption of xenon molecules from a mixture of xenon and krypton. Furthermore, the ultra-microporous metal-organic framework material of the present invention has a customized pore size, enabling it to generate stronger and more numerous interaction forces with xenon, which has a larger atomic size, thereby achieving the separation of xenon / krypton gas mixtures.

[0021] The inventors discovered that the specific structure described above in this invention contains [B] 12 H 12 ] 2- Anionic, ultraporous metal-organic frameworks possess excellent hydrothermal stability, enabling them to withstand harsh industrial applications. They can selectively adsorb xenon from a mixture of xenon and krypton, achieving efficient separation of the xenon / krypton mixture. The adsorbent of this invention contains [B...] 12 H 12 ] 2- Anions can form a regular arrangement on the pore surface, creating a special electrostatic environment within the confined space of the pores in the specific structure of the material of this invention. On one hand, in the specific structure of the material of this invention, [B 12 H 12 ] 2-The introduction of anions enhances the material's selective recognition of xenon in a xenon / krypton mixture. Furthermore, the material's customized pore size further strengthens xenon recognition, thereby improving the selective separation of xenon and krypton. Both of these characteristics are indispensable; only when both are present can the effective separation of xenon and krypton as required by this invention be achieved.

[0022] The present invention [B] 12 H 12 ] 2- Anion-hybridized ultraporous metal-organic frameworks can be used directly as adsorbents alone, or they can be combined with other materials to form adsorbent materials of different shapes and sizes. This meets the particle size requirements of various industrial reaction devices for adsorbent packing materials.

[0023] Fifthly, the present invention provides a method for separating xenon and krypton, comprising: contacting a mixture of xenon and krypton with the microporous metal-organic framework material described in the first aspect, wherein the microporous metal-organic framework material selectively adsorbs xenon in the mixture, thereby achieving the separation of xenon and krypton.

[0024] In some preferred embodiments, the xenon and krypton mixture contains xenon gas with a total molar amount of xenon and krypton of 100%, and the xenon molar content is between 10% and 90%, or more specifically between 10% and 50%, such as 20%.

[0025] In some preferred embodiments, the contact method includes any one or a combination of two or more of fixed-bed adsorption, fluidized-bed adsorption, and moving-bed adsorption.

[0026] In some preferred embodiments, the contact method includes fixed-bed adsorption, specifically comprising: at a set adsorption temperature and pressure, a mixture of xenon and krypton gas is introduced at a set flow rate into a fixed-bed adsorption column packed with the ultraporous metal-organic framework material. The krypton component preferentially penetrates the bed, and high-purity krypton gas is directly obtained from the adsorption column outlet, while xenon gas is adsorbed in the fixed-bed adsorption column. Furthermore, high-purity xenon gas can be obtained by desorption at the set adsorption temperature and pressure. The xenon gas can be recycled by regenerating the adsorbent using methods such as heating and vacuum desorption, and the recovered high-purity xenon gas can be further commercialized.

[0027] In some preferred embodiments, the adsorption temperature is 0~40 °C.

[0028] In some preferred embodiments, the adsorption pressure is 0.5 to 10 atm.

[0029] In some preferred embodiments, the method in the fifth aspect further includes: selectively adsorbing xenon from the mixed gas using the microporous metal-organic framework material to separate xenon from krypton, and then desorbing the xenon under conditions of 30-100 °C and 0-1 atm to achieve xenon recovery and regeneration of the microporous metal-organic framework material. In this invention, the interaction between the microporous metal-organic framework material and gas molecules is a physical force, making desorption and regeneration easy and under mild conditions.

[0030] This invention can adsorb xenon gas from a xenon / krypton gas mixture with high capacity and selectivity. The adsorbent (ultraporous metal-organic framework material) is easy to regenerate and has good hydrothermal stability.

[0031] Compared with the prior art, the beneficial effects of this invention are as follows: 1) On the one hand, containing [B] 12 H 12 ] 2- The anionic ultraporous metal-organic framework has a large number of regularly arranged, high-density negatively charged [B] atoms. 12 H 12 ] 2- Anion sites can create a special electrostatic environment within the pores, due to xenon's significantly high polarizability (40.44 × 10⁻⁶). -25 cm 3 Krypton is 24.84 × 10 -25 cm 3 The material can selectively identify xenon and efficiently exclude other gases such as krypton. On the other hand, the ultra-microporous metal-organic framework material has a customized pore size that matches xenon, thereby generating stronger and more numerous interaction forces with xenon, achieving the separation of the xenon / krypton mixture. The combined synergistic effect of these two aspects is necessary to achieve the highly efficient separation of xenon and krypton achieved in this invention.

[0032] 2) Ultra-microporous metal-organic framework materials are easy to desorb and regenerate, which is a great advantage over traditional adsorbent materials. It can reduce the energy consumption of MOF regeneration. At the same time, the material can be regenerated and reused.

[0033] 3) Microporous metal-organic frameworks have extremely strong water stability and cycle stability. The excellent stability also shows the potential of microporous metal-organic framework materials in industrial applications. Attached Figure Description

[0034] Figure 1 Zn(B) in Example 1 12 H 12 Crystal structure diagram of TPE(H2O)2.

[0035] Figure 2 Zn(B) in Example 312 H 12 Adsorption isotherms of xenon and krypton in TPE(H2O)2 at 298 K and 0-100 kPa.

[0036] Figure 3 Zn(B) in Example 5 12 H 12 The breakthrough curve of TPE(H2O)2 separating a xenon / krypton mixture with a molar ratio of 20 / 80 at 298 K and a flow rate of 2 mL / min. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0038] Example 1: 18 mg of Zn[NO3]2·3H2O was mixed with 14 mg of Na2B 12 H 12 Dissolve 2H₂O in 10 mL of water (solution A), then dissolve 40 mg of 1,1,2,2-tetratetra(pyridin-4-yl)ethylene (TPE) in 10 mL of methanol (solution B). Prepare 20 mL of methanol / water (1 / 1 volume ratio) buffer solution. Finally, add 1 mL of solution A, 2 mL of buffer solution, and 1 mL of solution B to a 5 mL test tube. Seal the test tube and let it stand at room temperature for one week to obtain transparent and colorless Zn(B) crystals. 12 H 12 TPE(H2O)2, namely the ultramicroporous metal-organic framework material of this invention. Crystal analysis revealed that Zn(B) 12 H 12 The crystal parameters of TPE(H2O)2 are shown in Table 1, and the structure is as follows: Figure 1 As shown.

[0039] Table 1 Example 2: In a 50 mL round-bottom flask, 330 mg of Na₂B 12 H 12·2H2O and 450 mg of Zn[NO3]2·6H2O were dissolved in 15 mL of water. In another 50 mL round-bottom flask, 500 mg of 1,1,2,2-tetratetra(pyridin-4-yl)ethylene (TPE) was dissolved in 30 mL of methanol. The methanol solution was added dropwise to the aqueous solution, and the mixture was stirred at 50 °C for 48 hours to obtain a white solid precipitate. The precipitate was filtered and washed with methanol. The solid was then immersed in anhydrous methanol, with the methanol being replaced every six hours for a total of at least three replacements to remove free water molecules from the pores of the material, thus obtaining the ultramicroporous metal-organic framework material Zn(B 12 H 12 TPE(H2O)2, whose crystal parameters and crystal structure are the same as those in Example 1.

[0040] Example 3: Approximately 100 mg of Zn(B) obtained in Example 2 12 H 12 TPE(H2O)2 material was loaded into an adsorption tube, and after being evacuated at room temperature for two hours, it was activated by evacuating at 75 °C for 10 hours. Then, under conditions of 298 K, single-component gas adsorption experiments of xenon and krypton were conducted using an adsorption apparatus, and their single-component gas adsorption curves were measured as shown below. Figure 2 As shown. Specifically at 298 K and 100 kPa, Zn(B 12 H 12 The xenon adsorption capacity of TPE(H2O)2 can reach 41.28 cm⁻¹. 3 / g, krypton adsorption capacity is 16.70cm³. 3 / g.

[0041] Example 4: Using the unit-point Langmuir model to analyze Zn(B) in Example 2 12 H 12 The adsorption isotherms of xenon or krypton gas in TPE(H2O)2 were fitted, and then the parameters obtained from the fitting were used to calculate the Zn(B) adsorption at 298 K and 100 kPa using the Ideal Solution Adsorption Theory (IAST). 12 H 12 The xenon / krypton (20 / 80, v / v) separation selectivity of TPE(H2O)2 is 11.84, indicating that Zn(B) 12 H 12 TPE(H2O)2 can achieve efficient separation of xenon / krypton gas.

[0042] Example 5: The Zn(B) obtained in Example 2 12 H 12TPE(H2O)2 material was ground into a uniform fine powder and packed into an adsorption column with an inner diameter of 0.5 cm and a length of 5 cm. After activation at 75 ℃ for 10 hours, a xenon and krypton mixture (20 / 80, v / v) was introduced into the adsorption column at room temperature (25 ℃) at a rate of 2 mL / min. It was observed that Kr preferentially emerged, followed by Xe after a certain period. The breakthrough curve is shown below. Figure 3 As shown.

[0043] Example 6: In a 50 mL round-bottom flask, 330 mg of Na₂B 12 H 12 ·2H2O and 440 mg of Co[NO3]2·6H2O were dissolved in 15 mL of water. In another 50 mL round-bottom flask, 500 mg of 1,1,2,2-tetratetra(pyridin-4-yl)ethylene (TPE) was dissolved in 30 mL of methanol. The methanol solution was added dropwise to the aqueous solution, and the mixture was stirred at 50 °C for 48 hours to obtain an orange solid precipitate. The precipitate was filtered and washed with methanol. The solid was then immersed in anhydrous methanol, with the methanol being replaced every six hours for a total of at least three replacements to remove free water molecules from the pores of the material, thus obtaining the ultramicroporous metal-organic framework material Co(B) 12 H 12 TPE(H2O)2. Approximately 100 mg of Co(B) will be obtained. 12 H 12 TPE(H2O)2 material was loaded into an adsorption tube and activated by vacuuming at room temperature for two hours, followed by vacuuming at 75 °C for 10 hours. Then, single-component gas adsorption experiments of xenon and krypton were conducted using an adsorption apparatus at 298 K, and their single-component gas adsorption curves were measured. The adsorption isotherms of single-component xenon or krypton were fitted using a unit-point Langmuir model. The fitted parameters and the ideal solution adsorption theory (IAST) were then used to calculate the adsorption temperature of Co(B) at 298 K and 100 kPa. 12 H 12 The xenon / krypton (20 / 80, v / v) separation selectivity of TPE(H2O)2 is 10.34, indicating that Co(B) 12 H 12 TPE(H2O)2 can achieve efficient separation of xenon / krypton gas.

[0044] Example 7: In a 50 mL round-bottom flask, 330 mg of Na₂B 12 H 12·2H2O and 400 mg of Cu[NO3]2·3H2O were dissolved in 15 mL of water. In another 50 mL round-bottom flask, 500 mg of 1,1,2,2-tetratetra(pyridin-4-yl)ethylene (TPE) was dissolved in 30 mL of methanol. The methanol solution was added dropwise to the aqueous solution, and the mixture was stirred at 50 °C for 48 hours to obtain a blue solid precipitate. The precipitate was filtered and washed with methanol. The solid was then immersed in anhydrous methanol, with the methanol being replaced every six hours for a total of at least three replacements to remove free water molecules from the pores of the material, thus obtaining the ultramicroporous metal-organic framework material Cu(B) 12 H 12 TPE(H2O)2. Approximately 100 mg of Cu(B) was obtained. 12 H 12 TPE(H2O)2 material was loaded into an adsorption tube and activated by vacuuming at room temperature for two hours, followed by vacuuming at 75 °C for 10 hours. Then, single-component gas adsorption experiments of xenon and krypton were conducted at 298 K using an adsorption apparatus, and their single-component gas adsorption curves were measured. The adsorption isotherms of single-component xenon or krypton were fitted using a unit-point Langmuir model. The fitted parameters and the ideal solution adsorption theory (IAST) were then used to calculate the adsorption isotherms of Cu(B) at 298 K and 100 kPa. 12 H 12 The xenon / krypton (20 / 80, v / v) separation selectivity of TPE(H2O)2 was 11.21, indicating that Cu(B) 12 H 12 TPE(H2O)2 can achieve efficient separation of xenon / krypton gas.

[0045] Example 8: In a 50 mL round-bottom flask, 330 mg of Na₂B 12 H 12 440 mg of Ni[NO3]2·6H2O was dissolved in 15 mL of water. In another 50 mL round-bottom flask, 500 mg of 1,1,2,2-tetra(pyridin-4-yl)ethylene (TPE) was dissolved in 30 mL of methanol. The methanol solution was added dropwise to the aqueous solution, and the mixture was stirred at 50 °C for 48 hours, yielding a blue solid precipitate. This precipitate was filtered and washed with methanol. The solid was then immersed in anhydrous methanol, with the methanol being replaced every six hours for a total of at least three replacements to remove free water molecules from the pores of the material, resulting in the ultramicroporous metal-organic framework material Ni(B)2·6H2O. 12 H 12 TPE(H2O)2. Approximately 100 mg of Ni(B) will be obtained. 12 H 12TPE(H2O)2 material was loaded into an adsorption tube and activated by vacuuming at room temperature for two hours, followed by vacuuming at 75 °C for 10 hours. Then, single-component gas adsorption experiments of xenon and krypton were conducted using an adsorption apparatus at 298 K, and their single-component gas adsorption curves were measured. The adsorption isotherms of single-component xenon or krypton were fitted using a unit-point Langmuir model. The fitted parameters and the ideal solution adsorption theory (IAST) were then used to calculate the adsorption isotherms of Ni(B) at 298 K and 100 kPa. 12 H 12 The xenon / krypton (20 / 80, v / v) separation selectivity of TPE(H2O)2 is 10.99, indicating that Ni(B) 12 H 12 TPE(H2O)2 can achieve efficient separation of xenon / krypton gas.

[0046] Example 9: In a 50 mL round-bottom flask, 330 mg of Na₂B 12 H 12 ·2H2O and 611 mg of Fe[NO3]2·9H2O were dissolved in 15 mL of water. In another 50 mL round-bottom flask, 500 mg of 1,1,2,2-tetratetra(pyridin-4-yl)ethylene (TPE) was dissolved in 30 mL of methanol. The methanol solution was added dropwise to the aqueous solution, and the mixture was stirred at 50 °C for 48 hours to obtain a blue solid precipitate. The precipitate was filtered and washed with methanol. The solid was then immersed in anhydrous methanol, with the methanol being replaced every six hours for a total of at least three replacements to remove free water molecules from the pores of the material, thus obtaining the ultramicroporous metal-organic framework material Fe(B 12 H 12 TPE(H2O)2. Approximately 100 mg of Fe(B) will be obtained. 12 H 12 TPE(H2O)2 material was loaded into an adsorption tube and activated by vacuuming at room temperature for two hours, followed by vacuuming at 75 °C for 10 hours. Then, single-component gas adsorption experiments of xenon and krypton were conducted using an adsorption apparatus at 298 K, and their single-component gas adsorption curves were measured. The adsorption isotherms of single-component xenon or krypton were fitted using a unit-point Langmuir model. The fitted parameters were then used to calculate the adsorption isotherms of Fe(B) at 298 K and 100 kPa using the Ideal Solution Adsorption Theory (IAST). 12 H 12 The xenon / krypton (20 / 80, v / v) separation selectivity of TPE(H2O)2 was 9.98, indicating that Fe(B) 12 H 12 TPE(H2O)2 can achieve efficient separation of xenon / krypton gas.

[0047] 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 metal-organic framework material, characterized in that, A six-coordinated divalent metal cation M coordinates with a tetradentate nitrogen-containing ligand L in the horizontal direction to form an infinitely extended two-dimensional network structure, and then coordinates with two water molecules in the vertical direction to form two-dimensional secondary structural units. Finally, the divalent inorganic anion [B 12 H 12 ] 2- By forming double hydrogen bonds with water molecules with a length of 2.8~3.0 Å, they are embedded between two-dimensional layers to form a complete ultraporous metal-organic framework material; The molecular formula of the ultramicroporous metal-organic framework material is ML(B) 12 H 12 (H₂O)₂, where L is the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene, and the metal cation M is Cu. 2+ Ni 2+ Fe 2+ Co 2+ Zn 2+ One or more of them.

2. The method for preparing the ultramicroporous metal-organic framework material according to claim 1, characterized in that, include: The precursor of the metal cation M, and the inorganic anion [B] 12 H 12 ] 2- The precursor and the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene are mixed and reacted in a solvent to obtain the ultraporous metal-organic framework material.

3. The preparation method according to claim 2, characterized in that, The precursor of the metal cation M includes nitrate; The inorganic anion [B 12 H 12 ] 2- The precursors include sodium salts; The solvent includes methanol and water; The reaction temperature is room temperature to 60°C.

4. The preparation method according to claim 2 or 3, characterized in that, The preparation method specifically includes: adding solution A, buffer solution and solution B sequentially to a container, and allowing the reaction to proceed to obtain the ultramicroporous metal-organic framework material; Solution A includes a precursor of metal cation M and inorganic anion [B]. 12 H 12 ] 2- The precursor and solvent water; The buffer solution comprises methanol and water; Solution B comprises the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene and the solvent methanol.

5. The preparation method according to claim 2 or 3, characterized in that, The preparation method specifically includes: adding a methanol solution of the tetradentate nitrogen-containing ligand 1,1,2,2-tetra(pyridin-4-yl)ethylene to the precursor of the metal cation M and the inorganic anion [B 12 H 12 ] 2- The ultraporous metal-organic framework material is obtained by reacting in a mixed aqueous solution of the precursor.

6. The application of the ultramicroporous metal-organic framework material according to claim 1 for the adsorption of xenon gas.

7. The application of the ultramicroporous metal-organic framework material according to claim 1 for the adsorption and separation of xenon and krypton, characterized in that, The ultraporous metal-organic framework material selectively adsorbs xenon gas.

8. A method for separating xenon and krypton, characterized in that, include: A mixture of xenon and krypton is brought into contact with the microporous metal-organic framework material described in claim 1, wherein the microporous metal-organic framework material selectively adsorbs xenon from the mixture, thereby achieving the separation of xenon and krypton.

9. The method according to claim 8, characterized in that, In the mixture containing xenon and krypton, the total molar amount of xenon and krypton is 100%, and the molar content of xenon is 10% to 90%, and more specifically 10% to 50%. The contact method includes any one or a combination of two or more of fixed-bed adsorption, fluidized-bed adsorption, and moving-bed adsorption. The adsorption temperature is 0~40℃; The adsorption pressure is 0.5~10 atm.

10. The method according to claim 8 or 9, characterized in that, The method further includes: selectively adsorbing xenon gas from the mixed gas in the ultraporous metal-organic framework material to separate xenon gas from krypton gas, and then desorbing xenon gas under conditions of temperature 30~100℃ and pressure 0~1 atm to achieve xenon gas recovery and regeneration of the ultraporous metal-organic framework material.

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