A porous framework material based on a carborane skeleton, its preparation method and application

Abstract

This invention discloses a porous framework material based on a carborane framework, its preparation method, and its applications. The porous framework material is obtained by coordinating a metal ion M with a carboxylated carborane to form a two-dimensional planar structure, and then using an organic nitrogen-containing ligand as a pillar to form a three-dimensional framework structure; the metal ion M is selected from Cu. 2+ Zn 2+ Ni 2+ Co 2+ At least one of the following: the carboxycarborane is selected from at least one of para-carboxycarborane and meta-carboxycarborane; the organic nitrogen-containing ligand is selected from at least one of 1,4-diazabicyclo[2.2.2]octane, pyrazine, 4,4'-bipyridine, and piperazine. Preparation method: The salt containing metal ion M, the carboxycarborane, and the organic nitrogen-containing ligand are reacted in a solvent at 50-100℃ to obtain a solid product; the solid product is placed in methanol for one or more solvent exchanges to remove solvent molecules, and then vacuum degassing and activation are performed to remove methanol molecules from the channels to obtain a porous framework material.

Description

Technical Field

[0001] This invention relates to the fields of porous material synthesis and gas adsorption technology, specifically to a porous framework material based on a carborane skeleton, its preparation method, and its application. Background Technology

[0002] Polymer-grade ethylene (C2H4 ≥ 99.95%) is a key raw material widely used in the production of polymers and high-value organic chemicals. In recent years, scientists have agreed on the need for an economical and efficient purification method to remove ethane (C2H6), an unavoidable byproduct of C2H4. Adsorption separation technology based on porous materials has attracted widespread attention due to its advantages such as energy saving, environmental friendliness, reusability, and high production efficiency. However, C2H6... and C2H4 The extremely similar molecular sizes of C2H6 and C2H4 pose a significant challenge to finding suitable porous materials. Although there are reports of separating C2H6 / C2H4 through pore engineering design of molecular sieve materials, achieving a one-step extraction of high-purity C2H4 remains very difficult.

[0003] Metal-organic frameworks (MOFs) are a new type of porous material that have shown great potential for gas storage and separation due to their high surface area and pore volume, ordered crystal structure and tunable pore environment.

[0004] The organic ligand frameworks of current metal-organic frameworks (MOFs) mainly consist of benzene rings and benzene ring derivatives. However, regardless of the different functions and sizes of the aromatic units and phenyl linkers, the inherent planarity of the phenyl ring cannot be changed, thus limiting the composition and application of the organic linkers. Carborane framework linkers possess a natural 3D structure, providing consistent pore size and more functionality throughout the MOF. Furthermore, the surface of carborane framework linkers is rich in negative hydrogen atoms, which can enhance adsorption capacity and separation efficiency through dihydrogen bonding between negative and positive hydrogen atoms. Boron cluster anion hybrid MOFs such as BSF-3 (Angew. Chem. Int. Ed. 2020, 59, 17664-17669) and ZNU-1 (Angew. Chem. Int. Ed. 2021, 60, 22865-22870) have been developed as benchmark materials for capturing acetylene in C2H2 / CO2 and C2H2 / C2H4 mixtures. The closed dodecanoate anions [B] on the pore surface... 12 H 12 ] 2- Acetylene can be selectively captured through specific double hydrogen bond interactions.

[0005] The patent specification with publication number CN110193352A discloses a functionalized cage-like borane anion-supported supramolecular microporous framework material, which is composed of metallic Cu. 2+ The ion coordinates with the bidentate linear organic nitrogen-containing ligand L to form a two-dimensional planar structure, and then with the iodine-substituted functionalized cage-like dodecorane anion [B 12 H 11 I] 2- The bridging forms a three-dimensional layered columnar framework structure, which can be used for the selective purification of methane.

[0006] The patent specification with publication number CN109851810A discloses a borane anion supramolecular organic framework material. This material first forms a two-dimensional planar structure by coordination of metal ions M with bidentate linear organic nitrogen-containing ligands L, and then utilizes cage-like borane anions [B... 12 H 12 ] 2- Or [B] 10 H 10 ] 2- It is obtained by forming a three-dimensional framework structure through supramolecular interactions such as various negative hydrogen-positive hydrogen dihydrogen bonds and negative hydrogen-metal interactions, which can be used for highly selective adsorption and separation of propane / ethane / methane, carbon dioxide / methane, and acetylene / ethylene.

[0007] The borane anions used in the above-mentioned prior art are different from the carborane used in this patent application.

[0008] Based on ethylene (42.52×10 -25 cm 3 The polarizability of ) is lower than that of ethane (44.7 × 10⁻⁶). -25 cm 3 Given the fact that reducing the electrostatic potential of the pore surface in porous materials is expected to achieve preferential adsorption of ethane compared to ethylene, this invention replaces boron cluster anions with neutral carboranes (C2B). 10 H 12 By altering the electrostatic potential within the pores, ethylene can be purified from C2H6 / C2H4 in one step. This is based on neutral carborane (p-C2B) 10 H 12 and m-C2B 10 H 12 The use of ) as a framework for the separation of organic framework materials for C2H6 / C2H4 has never been reported to date. Summary of the Invention

[0009] This invention provides a porous framework material based on a carborane skeleton that can selectively adsorb ethane from a mixed system containing ethane and ethylene.

[0010] The specific technical solution is as follows:

[0011] A porous framework material based on a carborane skeleton that can selectively adsorb ethane from a mixed system containing ethane and ethylene is obtained by coordinating metal ions M with carboxylated carborane to form a two-dimensional planar structure, and then using organic nitrogen-containing ligands as pillars to form a three-dimensional framework structure.

[0012] The metal ion M is selected from Cu. 2+ Zn 2+ Ni 2+ Co 2+ At least one of them;

[0013] The carboxycarborane is selected from at least one of para-carboxycarborane and meta-carboxycarborane;

[0014] The expression for the para-carboxylated carboborane is p-C2B. 10 H 10 (COOH)₂ has the structure shown in formula (I):

[0015]

[0016] The expression for the meta-carboxylated carboborane is m-C2B. 10 H 10 (COOH)2 has the structure shown in formula (II):

[0017]

[0018] The organic nitrogen-containing ligand is selected from at least one of 1,4-diazabicyclo[2.2.2]octane, pyrazine, 4,4'-bipyridine, and piperazine, and the corresponding chemical structures are shown below:

[0019]

[0020] This invention also provides a method for preparing the aforementioned porous framework material based on a carborane skeleton, comprising the following steps:

[0021] (1) The salt containing metal ion M, carboxylated carborane and organic nitrogen-containing ligand are reacted in a solvent at 50-100℃ to obtain a solid product;

[0022] (2) The solid product is placed in methanol for one or more solvent exchanges to remove solvent molecules, and then vacuum degassing and activation are performed to remove methanol molecules in the pores to obtain the porous framework material based on the carborane skeleton.

[0023] In step (1), the salt containing metal ion M can be selected from at least one of the following: nitrate, chloride, and tetrafluoroborate of metal ion M.

[0024] The metal ion M described in this invention has a positive divalent charge, and the carboxycarborane ion has a negative divalent charge. In order to achieve charge balance, the preferred molar ratio of the two is 1:1.

[0025] In a preferred embodiment, in step (1), the molar ratio of the salt containing metal ion M, the carboxycarborane, and the organic nitrogen-containing ligand is 2:2:1.

[0026] In step (1), the solvent may be selected from at least one of methanol, DMF (N,N-dimethylformamide), water, DMA (N,N-dimethylacetamide), ethanol, acetone, and acetonitrile, preferably a mixture of methanol, DMF, and water.

[0027] In step (1), the reaction time can be 4 to 48 hours.

[0028] In step (2), the time for each solvent exchange can be 5 to 8 hours.

[0029] In step (2), the temperature for vacuum degassing activation can be room temperature to 140°C, and the time can be 12 to 24 hours.

[0030] The present invention also provides the application of the aforementioned porous framework material based on a carborane skeleton in the field of selective adsorption and separation of gases.

[0031] Furthermore, the porous framework material based on the carborane skeleton is particularly suitable for selectively adsorbing ethane from a mixed system containing ethane and ethylene, thereby achieving the separation of ethane and ethylene.

[0032] Compared with the prior art, the beneficial effects of this invention are as follows:

[0033] 1) The porous framework material based on carborane skeleton designed and synthesized in this invention has unique structural characteristics. Using carborane as a skeleton improves the inherent planarity of the phenyl ring, thereby improving the limitations of organic linkers in terms of composition and application.

[0034] 2) Replace the boron cluster anion with a neutral carborane (C2B) 10 H 12 By changing the electrostatic potential in the pores, preferential adsorption of ethane over ethylene was achieved.

[0035] 3) This invention uses cage-like polyhedral carborane as a framework. Due to the delocalization of its charge, it exhibits stronger thermal and chemical stability and is expected to be applied to the synthesis of porous materials.

[0036] 4) The porous framework material based on a carborane skeleton designed and synthesized in this invention has high separation selectivity for ethane / ethylene. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the crystal structure of ZNU-10, a porous framework material based on a carborane skeleton, in Example 1.

[0038] Figure 2 This is the 77K nitrogen adsorption curve of ZNU-10 in Example 1;

[0039] Figure 3 This is a single-component adsorption curve of ethane in ZNU-10 determined at 273K, 298K, and 308K in Example 1.

[0040] Figure 4 This is a single-component adsorption curve of ethylene in ZNU-10 measured at 273K, 298K, and 308K in Example 1.

[0041] Figure 5 This is the ethane and ethylene adsorption heat curve of ZNU-10 calculated based on the isotherm in Example 1;

[0042] Figure 6 The image shows the IAST selectivity diagram for the separation of ethane / ethylene mixed gases, calculated by ZNU-10 based on isotherms in Example 1.

[0043] Figure 7 Thermogravimetric curve of ZNU-10 in Example 1;

[0044] Figure 8 Powder X-ray diffraction (PXRD) patterns of ZNU-10 at different temperatures in Example 1;

[0045] Figure 9 This is a graph showing the water adsorption test curve of ZNU-10 in Example 1. Detailed Implementation

[0046] 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.

[0047] Example 1

[0048] In a 30 mL reaction vessel, Cu(NO3)2·3H2O containing 9.68 mg (0.04 mmol) and p-C2B were added. 10 H 10(COOH)₂ and 2.24 mg (0.02 mmol) of 1,4-diazabicyclo[2.2.2]octane were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, a blue transparent solution was obtained. The reaction vessel was sealed and reacted at 80 °C for 6 h to obtain blue-green transparent crystals. The blue-green transparent crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuuming at room temperature for 2 h, the temperature was raised to 120 °C for vacuum activation for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-10.

[0049] Figure 1 This is a schematic diagram of the crystal structure of ZNU-10. Cu 2+ The Cu2(COO)4 unit is formed by connecting with the carboxyl group in the para-carboxycarborane. The Cu2 unit with the paddle-shaped structure extends alternately in the two-dimensional direction by connecting with the four carboxyl groups from the four para-carboxycarboranes respectively, forming a square grid layer. The 1,4-diazabicyclo[2.2.2]octane ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0050] The activated material was subjected to adsorption-desorption experiments at 77K N2 under liquid nitrogen conditions, and the results are as follows: Figure 2 As shown.

[0051] Then, the single-component adsorption curves of ZNU-10 for ethane and ethylene were measured at 273 K, 298 K, and 303 K. The adsorption heat curves of ZNU-10 for the above gases were calculated and fitted using the Clausians-Clapeyron equation, as shown below. Figures 3-5 As shown. Figure 6 As shown, the separation selectivity for ethane / ethylene for single-component and two-component gases was obtained based on the Ideal Adsorption Solution Theory (IAST) and adsorption data fitting. The selectivity for ethane / ethylene at 298 K was 1.66.

[0052] Thermogravimetric analysis indicates that the thermal stability temperature of ZNU-10 is approximately 340℃. Figure 7 ZNU-10 was subjected to variable-temperature PXRD testing, and its powder diffraction pattern remained unchanged at 320℃, indicating that this organic framework material has good thermal stability. Figure 8 ).

[0053] Water adsorption analysis showed that ZNU-10 adsorbed very little water, indicating hydrophobicity. Figure 9 ).

[0054] 1 g of ZNU-10 crystals were packed into an adsorption column with an inner diameter of 0.5 cm and a length of 10 cm. At room temperature (25°C), a mixture of ethane and ethylene with a volume ratio of 10 / 90 was introduced into the column at a rate of 2 mL / min. Ethylene permeated through the column before ethane, and ethane permeated through 18 minutes later. This demonstrates that ZNU-10 can effectively adsorb ethane in an ethane / ethylene mixture, achieving highly selective separation.

[0055] Example 2

[0056] In a 30 mL reaction vessel, Cu(NO3)2·3H2O containing 9.68 mg (0.04 mmol) and m-C2B were added. 10 H 10 (COOH)₂ and 2.24 mg (0.02 mmol) of 1,4-diazabicyclo[2.2.2]octane were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, the reaction vessel was sealed and reacted at 80 °C for 6 h to obtain crystals. The crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuuming at room temperature for 2 h, the temperature was raised to 120 °C for vacuum activation for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-102.

[0057] In the ZNU-102 crystal structure, Cu 2+ The Cu2 unit is formed by connecting with the carboxyl group in the meta-carboxycarborane to form a paddle wheel unit Cu2(COO)4. The paddle wheel-shaped Cu2 unit is connected with the four carboxyl groups from the four meta-carboxycarboranes respectively, and extends alternately in the two-dimensional direction to form a grid layer. The 1,4-diazabicyclo[2.2.2]octane ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0058] Due to the non-polar nature of the ZNU-102 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By loading 1g of ZNU-102 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0059] Example 3

[0060] In a 30 mL reaction vessel, Cu(NO3)2·3H2O containing 9.68 mg (0.04 mmol) and p-C2B were added.10 H 10 (COOH)₂ and 1.60 mg (0.02 mmol) of pyrazine were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, the reaction vessel was sealed and reacted at 80 °C for 6 h to obtain crystals. The crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuum activation at room temperature for 2 h, the temperature was raised to 120 °C for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-103.

[0061] In the ZNU-103 crystal structure, Cu 2+ The Cu2 unit, which is connected to the carboxyl group in the para-carboxycarborane, forms a paddle wheel unit Cu2(COO)4. The paddle wheel-shaped Cu2 unit extends alternately in the two-dimensional direction to form a grid layer by connecting to the four carboxyl groups from the four para-carboxycarboranes respectively. The pyrazine organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0062] Due to the non-polar nature of the ZNU-103 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By loading 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0063] Example 4

[0064] In a 30 mL reaction vessel, Cu(NO3)2·3H2O containing 9.68 mg (0.04 mmol) and p-C2B were added. 10 H 10 (COOH)₂ and 3.12 mg (0.02 mmol) of 4,4'-bipyridine were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, the reaction vessel was sealed and reacted at 80 °C for 6 h to obtain crystals. The crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuum activation at room temperature for 2 h, the temperature was raised to 120 °C for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-104.

[0065] In the ZNU-104 crystal structure, Cu 2+The Cu2 unit, Cu2(COO)4, is formed by connecting with the carboxyl groups in the para-carboxycarborane. The Cu2 unit with the propeller-shaped structure extends alternately in the two-dimensional direction to form a grid layer by connecting with the four carboxyl groups from the four para-carboxycarboranes respectively. The 4,4'-bipyridine organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0066] Due to the non-polar nature of the ZNU-104 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By loading 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0067] Example 5

[0068] In a 30 mL reaction vessel, Cu(NO3)2·3H2O containing 9.68 mg (0.04 mmol) and p-C2B were added. 10 H 10 (COOH)₂ and 1.72 mg (0.02 mmol) of piperazine were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, the reaction vessel was sealed and reacted at 80 °C for 6 h to obtain crystals. The crystals were filtered and washed with methanol. The crystals were then subjected to displacement in anhydrous methanol three times at 8-h intervals to remove solvent molecules from the pores of the material. After vacuum activation at room temperature for 2 h, the temperature was raised to 120 °C for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-105.

[0069] In the ZNU-105 crystal structure, Cu 2+ The Cu2 unit is formed by connecting with the carboxyl group in the para-carboxycarborane to form a paddle wheel unit Cu2(COO)4. The paddle wheel-shaped Cu2 unit extends alternately in the two-dimensional direction to form a grid layer by connecting with the four carboxyl groups from the four para-carboxycarboranes respectively. The piperazine organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0070] Due to the non-polar nature of the ZNU-105 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By packing 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0071] Example 6

[0072] In a 30 mL reactor, 11.63 mg (0.04 mmol) of Ni(NO3)2·6H2O and 9.28 mg (0.04 mmol) of p-C2B were added. 10 H 10 (COOH)₂ and 2.24 mg (0.02 mmol) of 1,4-diazabicyclo[2.2.2]octane were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, a light green transparent solution was obtained. The reaction vessel was sealed and reacted at 80 °C for 6 h to obtain light green transparent crystals. The light green transparent crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuuming at room temperature for 2 h, the temperature was raised to 120 °C for vacuum activation for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-106.

[0073] ZNU-106 crystal structure consists of Ni 2+ A grid layer is formed by connecting with para-carboxylated carboborane, and the 1,4-diazabicyclo[2.2.2]octane organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0074] Due to the non-polar nature of the ZNU-106 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By loading 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0075] Example 7

[0076] In a 30 mL reactor, 11.64 mg (0.04 mmol) of Co(NO3)2·6H2O and 9.28 mg (0.04 mmol) of p-C2B were added. 10 H 10(COOH)₂ and 2.24 mg (0.02 mmol) of 1,4-diazabicyclo[2.2.2]octane were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, a red transparent solution was obtained. The reaction vessel was sealed and reacted at 80 °C for 6 h to obtain red transparent crystals. The red transparent crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuuming at room temperature for 2 h, the temperature was raised to 120 °C for vacuum activation for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-107.

[0077] The crystal structure of ZNU-107 is composed of Co 2+ A grid layer is formed by connecting with para-carboxylated carboborane, and the 1,4-diazabicyclo[2.2.2]octane organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0078] Due to the non-polar nature of the ZNU-107 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By packing 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0079] Example 8

[0080] In a 30 mL reactor, 11.89 mg (0.04 mmol) of Zn(NO3)2·6H2O and 9.28 mg (0.04 mmol) of p-C2B were added. 10 H 10 (COOH)₂ and 2.24 mg (0.02 mmol) of 1,4-diazabicyclo[2.2.2]octane were dissolved in 2 mL of DMF, 2 mL of methanol, and 1 mL of water. After sonication for 10 minutes, a colorless and transparent solution was obtained. The reaction vessel was sealed and reacted at 80 °C for 6 h to obtain colorless and transparent crystals. The colorless and transparent crystals were filtered and washed with methanol. The crystals were then replaced three times with anhydrous methanol at 8-h intervals to remove solvent molecules from the pores of the material. After vacuuming at room temperature for 2 h, the temperature was raised to 120 °C for vacuum activation for 10 h to remove methanol molecules from the channels, resulting in an organic framework material based on a carborane skeleton, named ZNU-108.

[0081] The ZNU-108 crystal structure consists of Zn 2+A grid layer is formed by connecting with para-carboxylated carboborane, and the 1,4-diazabicyclo[2.2.2]octane organic nitrogen-containing ligand acts as a pillar to support the grid layer into a complete three-dimensional orthogonal lattice.

[0082] Due to the non-polar nature of the ZNU-108 pore surface, its interaction force with ethane is greater than that with ethylene. Therefore, its ethane adsorption capacity is greater than that of ethylene, making it suitable for the selective adsorption and separation of ethane and ethylene. By packing 1g of ZNU-103 crystals into an adsorption column with an inner diameter of 0.5cm and a length of 10cm, and at room temperature (25℃), a mixture of ethane / ethylene with a volume ratio of 10 / 90 is introduced into the adsorption column at a rate of 2mL / min. This allows ethylene to permeate through first, followed by ethane.

[0083] 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. The application of a porous framework material based on a carborane framework capable of selectively adsorbing ethane from a mixed system containing ethane and ethylene in the field of selective gas adsorption and separation, characterized in that, The porous framework material based on the carborane skeleton is used to selectively adsorb ethane from a mixed system containing ethane and ethylene, thereby achieving the separation of ethane and ethylene. The porous framework material based on carborane skeleton is obtained by coordinating metal ions M with carboxylated carborane to form a two-dimensional planar structure, and then using organic nitrogen-containing ligands as pillars to form a three-dimensional framework structure; The metal ion M is selected from Cu. 2+ Zn 2+ Ni 2+ Co 2+ At least one of them; The carboxycarborane is selected from at least one of para-carboxycarborane and meta-carboxycarborane; The expression for the para-carboxylated carboborane is as follows: p -C2B 10 H 10 (COOH)2 has the structure shown in formula (I): （I）； The expression for the meta-carboxylated carboborane is as follows: m -C2B 10 H 10 (COOH)2 has the structure shown in formula (II): (II); The organic nitrogen-containing ligand is selected from at least one of 1,4-diazabicyclo[2.2.2]octane, pyrazine, 4,4'-bipyridine, and piperazine.

2. The application according to claim 1, characterized in that, The method for preparing porous framework materials based on carborane skeletons includes the following steps: (1) The salt containing metal ion M, carboxycarborane and organic nitrogen-containing ligand are reacted in a solvent at 50~100℃ to obtain a solid product; (2) The solid product is placed in methanol for one or more solvent exchanges to remove solvent molecules, and then vacuum degassing and activation are performed to remove methanol molecules in the channels to obtain the porous framework material based on the carborane skeleton.

3. The application according to claim 2, characterized in that, In step (1), the salt containing metal ion M is selected from at least one of the nitrate, chloride, and tetrafluoroborate of metal ion M.

4. The application according to claim 2, characterized in that, In step (1), the molar ratio of the salt containing metal ion M, the carboxylated carborane, and the organic nitrogen-containing ligand is 2:2:

1.

5. The application according to claim 2, characterized in that, In step (1), the solvent is selected from at least one of methanol, DMF, water, DMA, ethanol, acetone, and acetonitrile.

6. The application according to claim 2, characterized in that, In step (1), the reaction time is 4 to 48 hours.

7. The application according to claim 2, characterized in that, In step (2), the solvent exchange time is 5 to 8 hours each time.

8. The application according to claim 2, characterized in that, In step (2), the temperature for vacuum degassing activation is room temperature to 140°C, and the time is 12 to 24 hours.

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