Alkynyl functionalized hydrogen bond organic framework material for efficient reverse separation of propylene / propane as well as preparation method and application of alkynyl functionalized hydrogen bond organic framework material

Abstract

The invention discloses an alkynyl functionalized hydrogen bond organic framework (HOF) material for efficient reverse separation of propylene / propane as well as a preparation method and application of the alkynyl functionalized hydrogen bond organic framework (HOF) material. The preparation method comprises the following steps: dissolving a tetracarboxylic acid type organic ligand H4L in a benign organic solvent to obtain an H4L solution, then placing the H4L solution in a poor solvent steam atmosphere, and obtaining an HOF material through a gas phase diffusion method; after a low-boiling-point reagent is adopted to carry out solvent exchange on the HOF material, solvent molecules in pore channels of the HOF material are removed through an activation method, and then the alkynyl functionalized HOF material for propylene / propane efficient reverse separation is obtained. The material shows the characteristics of high propane adsorption capacity, excellent propylene / propane reverse separation performance, good cycle performance, easy repair and reproducibility, fills the technical blank of the HOF material in the field of efficient reverse separation of propylene / propane mixed gas, and provides a brand new thought and technical support for research and development in the field of light hydrocarbon separation.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen-bonded organic nanomaterials and important olefin gas purification, and specifically to an alkynyl-functionalized hydrogen-bonded organic framework (HOF) material for efficient reverse separation of propylene / propane, as well as a preparation method and application thereof. The HOF material is functionalized with electron-rich alkynyl groups, and the pore size and pore environment of the material are further controlled by regulating the number of alkynyl groups, ultimately achieving efficient reverse separation of propylene / propane mixed gas. Background Art

[0002] Propylene (C3H6) is a key chemical raw material for the industrial production of chemicals such as polypropylene, acrylonitrile, acrylic acid, and propylene oxide. It is widely used in plastics, healthcare, agriculture, and other fields. By 2023, global annual propylene production was expected to reach 160 million tons, second only to ethylene, making it one of the world's most produced chemical products. Industrially, propylene is primarily produced through naphtha steam cracking or propane (C3H8) dehydrogenation, but this process is accompanied by the formation of propane impurities. The separation of propylene and propane (C3H6 / C3H8) is a key step in the production of polymer-grade propylene (purity ≥99.5%). However, due to the extremely similar molecular size and volatility of the two, traditional cryogenic distillation technology requires repeated distillation-compression cycles using high-plate-count (>100) distillation columns under harsh conditions of 243K and 0.3MPa. This process is not only cumbersome and inefficient, but also results in significant energy and cost consumption. The purification of olefins and paraffin waxes accounts for approximately 1% of global carbon emissions, necessitating the development of energy-efficient and alternative separation technologies.

[0003] Adsorption separation technology based on porous materials offers the potential for low energy consumption and low cost, making it an ideal solution for propylene / propane separation. In recent years, progress has been made in propylene / propane separation using adsorbents such as metal-organic frameworks (MOFs) and zeolites. However, these materials often utilize their polar metal sites or metal clusters to strongly interact with unsaturated olefin molecules, requiring further desorption and multiple adsorption-desorption cycles to obtain high-purity propylene, increasing the complexity and energy consumption of the separation process. In contrast, propane-selective adsorbents can produce high-purity propylene directly at the outlet, significantly reducing separation energy consumption and saving approximately 40% of the energy required for pressure swing adsorption (PSA). However, designing such propane-selective adsorbents is extremely challenging. Currently, only a few MOFs have achieved reverse propylene / propane separation (C3H8 / C3H6) by introducing propane-binding sites (e.g., sites containing F groups or N / O atoms) or designing inert / nonpolar pore surfaces.

[0004] Studies have shown that porous materials with non-polar pore surfaces (e.g., with aromatic or aliphatic groups) tend to preferentially adsorb alkanes rather than alkenes. In this regard, porous hydrogen-bonded organic frameworks (HOFs), which are self-assembled from organic ligands through intermolecular hydrogen bonds, are purely organic and metal-free, and can provide a natural non-polar pore surface. They are considered to be very promising alkane-selective materials. HOFs have shown excellent performance in ethane / ethylene separation, and their separation mechanism may be applicable to propane / propylene separation. In addition, HOFs have unique advantages such as mild synthesis conditions, high solution processability, easy purification, easy regeneration, and self-healing, making the development of porous HOFs as propane-selective adsorbents very attractive. However, compared with ethane / ethylene separation, propane / propylene separation is more challenging because the polarity difference between propylene and propane molecules is smaller, the molecular size is very close, and the shape is complex.

[0005] Currently, the design of propane-selective HOFs still faces two major challenges: one is the lack of functional sites that can effectively enhance the propane adsorption capacity; the other is that the introduction of common functional sites (such as N or O sites) may lead to the destruction of the original hydrogen bond network, thereby causing the failure of HOF pore functionalization. Although some studies have attempted to use the size screening effect or introduce low-polarity sites to achieve selective adsorption of propylene molecules, to date, no research has successfully developed propane-selective HOFs that can achieve efficient propylene / propane reverse separation. Therefore, the design and optimization of porous HOFs with suitable functional sites and pore size to achieve propylene / propane reverse separation still has important academic value and application prospects, and further research and exploration are urgently needed. To solve the above technical problems, the present invention uses a network synthesis strategy to carefully design a tetracarboxylic acid-type alkynyl-functionalized organic ligand and successfully synthesizes a new isomorphously extended HOF material with sql topology. The prepared HOF material has regular and orderly one-dimensional pores. By regulating the number of alkynyl groups, the pore size and pore function of the HOF material are effectively regulated, significantly enhancing its selective adsorption performance for propane. The prepared HOF material with diacetylene groups exhibited excellent propane adsorption capacity and propane / propylene selectivity, achieving efficient reversal separation of propylene / propane for the first time, filling the technological gap in HOF material research in this field and laying a solid foundation for technological innovation and development in related fields. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides an alkynyl-functionalized hydrogen-bonded organic framework (HOFs) material for efficient inverse separation of propylene / propane, as well as a preparation method and application thereof. The present invention adopts a reticular synthesis strategy to successfully construct an isomorphous HOF material with an SQL topological structure, and by regulating the number of alkynyl groups, effectively adjusts the pore size and pore function of the HOF material, thereby significantly improving the performance of the HOF material in the propane / propylene separation process. Among them, the HOF with diacetylene sites can preferentially adsorb propane molecules in a propylene / propane mixture to obtain high-purity propylene in one step. The high propane adsorption capacity and good propane / propylene selectivity of the HOF material realize the efficient inverse separation of propylene / propane for the first time, providing a highly promising technical solution for industrial propane / propylene separation and propylene purification, and showing good application prospects.

[0007] The present invention adopts the following technical solutions:

[0008] A method for preparing an alkynyl-functionalized HOF material for efficient inverse separation of propylene / propane comprises:

[0009] Step 1: Dissolve the tetracarboxylic acid type organic ligand H4L in a benign organic solvent to obtain an H4L solution, which is then placed in a poor solvent vapor atmosphere to obtain the HOF material by a vapor diffusion method;

[0010] Step 2: After solvent exchange of the HOF material with a low-boiling-point reagent, the solvent molecules in the pores are removed by an activation method, thereby obtaining the alkynyl-functionalized HOF material for efficient propylene / propane inverse separation;

[0011] The tetracarboxylic acid type organic ligand H4L is any one of 5,5′-(ethynyl)diisophthalic acid and 5,5′-(butane-1,3-diyne-1,4-diyl)diisophthalic acid, and their structural formulas correspond to the following:

[0012]

[0013] Furthermore, the preparation method of the tetracarboxylic acid type organic ligand H4L comprises:

[0014] First, the ester of H4L functionalized with alkyne was obtained by Sonogashira coupling reaction, which was then hydrolyzed and then the target product H4L was obtained by rotary evaporation, acid addition, filtration and drying.

[0015] Furthermore, in step 1, the benign organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, ethanol, and methanol; preferably tetrahydrofuran; and the concentration of the H4L solution is 2-50 mg / mL.

[0016] Furthermore, in step 1, the poor solvent is one or more of diethyl ether, n-hexane, acetone, acetonitrile, dichloromethane, chloroform, ethyl acetate, petroleum ether, and cyclohexane; preferably ethyl acetate;.

[0017] Furthermore, in step 1, the temperature of the gas phase diffusion is 0-50°C; the gas phase diffusion time is 7-21 days; the preferred temperature is 25°C, and the preferred time is 14 days.

[0018] Furthermore, in step 2, the low-boiling-point reagent is one of anhydrous ether, anhydrous n-hexane, high-purity acetone, and high-purity dichloromethane, and the number of solvent exchanges is not less than 8 times, and the interval between each exchange is not less than 3 hours; preferably, high-purity acetone.

[0019] Furthermore, in step 2, the activation method is one or more of supercritical carbon dioxide activation, vacuum decompression, heating or gas purging, and the activation time is 6-48h; wherein, the supercritical carbon dioxide activation method is to use supercritical carbon dioxide for solvent exchange and then heat, dry and exhaust; the vacuum decompression method is to maintain the vacuum degree of the environment in which the material is located at 0.1-100Pa; the heating method is to maintain the temperature of the environment in which the material is located at 40-60°C; the gas of the gas purging method includes one or more of nitrogen, argon, helium and air.

[0020] An alkynyl functionalized HOF material for efficient propylene / propane inversion separation is prepared by any of the methods described above.

[0021] A propane selective adsorbent contains the alkynyl functionalized HOF material.

[0022] The application of the alkyne-functionalized HOF material in the efficient inversion separation of propylene / propane gas.

[0023] The inventive principle of the present invention is:

[0024] The present invention addresses the challenges of industrially important propylene / propane reverse separation and the difficulty in achieving functionalization of current propane-selective HOF materials. By introducing different numbers of alkynyl groups for functionalization using a network synthesis strategy, a new type of alkynyl-functionalized HOF material is designed and synthesized, which is characterized by a one-dimensional pore with a pore window diameter of High-efficiency separation performance of propane / propylene mixed gas was achieved. First, a high-purity tetracarboxylic acid organic ligand was synthesized through chemical reaction, and then a new alkyne-functionalized HOF material was prepared by gas phase diffusion method. By adding different tetracarboxylic acid organic ligands to control the number of alkyne groups, the pore size and pore function of the HOF material were effectively adjusted. Among them, the pore surface of the HOF material with diacetylene sites has abundant electronegative alkyne sites and carboxylic acid oxygen sites, and the pore size is large, which can ensure that the gas molecules and functional groups are fully in contact and interact, providing a favorable environment for the preferential adsorption of propane gas, thereby achieving efficient reverse separation of propylene / propane, filling the gap in HOF materials in this technical field, and showing good application prospects in the important industrial field of light hydrocarbon separation.

[0025] The beneficial effects of the present invention are:

[0026] This invention provides an alkynyl-functionalized hydrogen-bonded organic framework (HOF) material for efficient propylene / propane inverse separation and its preparation method. This fills a technological gap in HOF material research in this field and demonstrates promising application prospects in the important industrial field of light hydrocarbon separation. Compared with existing technologies, its main advantages are as follows:

[0027] (1) The organic molecular unit involved in the present invention has the advantages of being environmentally friendly and having good biocompatibility.

[0028] (2) A novel HOF material for propane / propylene separation was designed and synthesized. The material, which uses tetracarboxylic acid organic ligands as connectors and self-assembles via hydrogen bonding, exhibits excellent crystallinity, facilitating single crystal analysis to determine the material structure and investigate the relationship between structure and performance.

[0029] (3) The HOF material involved in the present invention has good structural design and functionality. Its structure is a typical sql two-dimensional network structure. Without introducing additional hydrogen bonds, the functional construction of the HOF structure is achieved. The isostructural HOF material is constructed using a network synthesis strategy. By selecting different tetracarboxylic acid organic ligands to change the number of introduced alkynyl groups, the pore size and pore function of the HOF material are effectively regulated. The pore surface is rich in electronegative alkynyl groups and carboxylic acid oxygen atoms, which can provide multiple binding sites for propane molecules.

[0030] (4) The HOF material of the present invention successfully achieves high propane adsorption capacity and high propane / propylene selectivity. The HOF material has a propane adsorption capacity of up to 146.8 cm at room temperature and pressure (298K and 1 bar). 3

[0031] g –1The propane / propylene separation selectivity under this condition is calculated to be 1.53, filling the technical gap of HOF materials in this field, and its comprehensive performance ranks among the best commercial porous materials and similar materials reported to date.

[0032] (5) The HOF material of the present invention has the characteristics of good cycle stability, simple preparation process, mild synthesis conditions, easy regeneration and self-repair, which is conducive to its large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The figure is a specific flow chart of the synthesis of organic ligands in the present invention.

[0034] Figure 2 Schematic diagram of the microscopic crystal structure of the material in the embodiment of the present invention.

[0035] Figure 3 This is the PXRD pattern of the materials in the examples of the present invention.

[0036] Figure 4 This is the 77K nitrogen isothermal full adsorption curve of the material in the embodiment of the present invention.

[0037] Figure 5 Comparison of single-component adsorption isotherms (298K) for propane and propylene in the examples of the present invention.

[0038] Figure 6 The single-component adsorption isotherms of propane and propylene at different temperatures (298K, 318K, 338K) for the materials in the examples of the present invention are shown.

[0039] Figure 7 This is the propane single-component cyclic adsorption curve of the material under 298K conditions in the embodiment of the present invention.

[0040] Figure 8 It is the IAST separation selectivity (298K) of the material in the embodiment of the present invention for propane / propylene (50 / 50, v / v) mixed gas.

[0041] Figure 9 2 is the PXRD pattern of the material before and after the adsorption test in the embodiment of the present invention.

[0042] Figure 10 This is a diagram of the adsorption sites of the materials in the examples of the present invention for propylene and propane molecules.

[0043] Figure 11 The material filling column in the embodiment of the present invention is at 298K, 1 bar total pressure and 1.25 mL min –1 50 / 50 propane / propylene dynamic breakthrough test curve conducted at total flow rate.

[0044] Figure 12 The material filling column in the embodiment of the present invention is at 298K, 1 bar total pressure and 1.25 mL min –1 Test curve of 50 / 50 propane / propylene dynamic circulation breakthrough experiment conducted at total flow rate. DETAILED DESCRIPTION

[0045] The contents of the present invention will be further illustrated below with reference to examples, but these examples do not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

[0046] Example 1

[0047] The synthesis of the tetracarboxylic acid organic ligand 5,5′-(ethynyl)diisophthalic acid (4) specifically comprises the following steps: ( Figure 1 ):

[0048] Synthesis of compound 5,5′-(1,2-ethynyl)di(1,3-phthalic acid)diethyl ester (3):

[0049] First, 20 mL of tetrahydrofuran and 10 mL of diisopropylamine were added to a 50 mL reaction flask, and the gas in the solvent was removed by bubbling with nitrogen. 35.5 mg of di(triphenylphosphine)palladium dichloride (II), 28.7 mg of copper (I) iodide, and 315 mg of 5-iodo-1,3-benzenedicarboxylate (1) were added to the reaction flask and stirred at 25°C for 30 minutes. Subsequently, 200 mg of 5-ethynyl-1,3-benzenedicarboxylate (2) was dissolved in 5 mL of tetrahydrofuran, and the solvent was added dropwise to the reaction flask, which was then allowed to react at 25°C for 24 hours. After the reaction, the organic solvent was dried by rotary evaporation, and the crude product was purified by column chromatography to obtain a light yellow compound 3 with high purity. Yield: 310 g, 82%. 1 H NMR (400MHz, CDCl3, ppm): δ = 8.68 (t, J = 1.6Hz, 2H), 8.40 (d, J = 1.6Hz 2H), 4.45 (q, J = 7.2Hz, 8H), 1.45 (t, J = 7.2Hz, 12H); 13 CNMR (100MHz, CDCl3) δ = 165.46, 136.87, 131.83, 130.94, 123.88, 89.50, 62.06, 14.72.

[0050] Synthesis of organic compound 5,5′-(ethynyl)diisophthalic acid (4):

[0051] 200 mg of compound 3, 240 mg of potassium hydroxide and 2 mL of methanol were added to a 250 mL reaction flask, and the mixture was heated to 80 °C for 12 h. After cooling, the organic layer was removed by spinning, and then a certain amount of water was added, and 2 mol L –1 The pH of the solution was adjusted to approximately 2 with HCl, resulting in the formation of a white precipitate. The resulting white precipitate was filtered, washed, and dried to obtain compound 4 of high purity (purity > 99%). Yield: 140 mg, 70%. 1 H NMR (400MHz, DMSO-d6, ppm): δ = 8.45 (s, 2H), 8.32 (s, 4H), 13.53 (bs, 4H); 13 C NMR (100MHz, DMSO-d6): δ=166.16, 136.24, 132.44, 130.51, 123.22, 89.31.

[0052] Synthesis of HOF materials:

[0053] To a 20 mL vial, add 10 mg of the tetracarboxylic acid-type organic ligand 5,5′-(ethynyl)diisophthalic acid and 5 mL of tetrahydrofuran. After sonication, dissolve the mixture and seal with plastic wrap. Then, poke a hole with a needle and place the vial in a 100 mL sealed bottle containing 30 mL of ethyl acetate. After two weeks of vapor diffusion at 25°C, colorless, transparent needle-shaped crystals, designated ZJU-HOF-60, are formed at the bottom of the vial.

[0054] The resulting homogeneous crystalline material was exchanged multiple times in high-purity acetone using a solvent exchange method, with each exchange interval of at least 3 hours. This was followed by a 3-hour exchange with liquid carbon dioxide, during which the liquid carbon dioxide was discharged for 5 minutes per hour under positive pressure, with the discharge rate of the liquid carbon dioxide always kept below the filling rate. After 3 hours of exhaust and soaking with liquid carbon dioxide, the drying chamber was sealed and the temperature was raised to 40°C. This caused the pressure in the chamber to exceed the critical point of carbon dioxide, 1300 psi. The chamber was maintained above the critical point for 1 hour, and then the chamber was slowly exhausted over 2 hours. Finally, the dried sample was vacuum degassed at 40°C for 12 hours, ultimately obtaining the ZJU-HOF-60 material with the solvent molecules removed.

[0055] Example 2

[0056] The synthesis of tetracarboxylic acid organic 5,5′-(butane-1,3-diyne-1,4-diyl) diisophthalic acid (6) specifically includes the following steps: Figure 1 ):

[0057] Synthesis of the organic compound 5,5′-(butane-1,4-diyne-1,4-diyl)bis(diethylisophthalate) (5):

[0058] 4.95 g of compound 1 and 6.00 g of copper acetate trihydrate were dissolved in a mixture of 25 mL of pyridine and 25 mL of methanol. The reaction mixture was stirred at 80°C under nitrogen for 24 hours. 20 mL of deionized water was added to the reaction solution, and an appropriate amount of concentrated hydrochloric acid (12N) was added to neutralize the pyridine. The solid precipitate was filtered and washed sequentially with deionized water and ethyl acetate to obtain purified compound 5 as a light white solid. Yield: 4.33 g, 8.8 mmol, 88%. 1 H NMR (300MHz, CDCl3, ppm): δ = 8.67 (t, J = 1.5Hz, 2H), 8.39 (d, J = 1.2Hz, 4H), 4.44 (q, J = 6.9Hz, 8H), 1.44 (t, J = 6.9Hz, 12H); 13 C NMR (75MHz, CDCl3, ppm): δ = 165.0, 136.4, 131.4, 130.5, 123.4, 89.0, 61.6, 14.2.

[0059] Synthesis of the organic compound 5,5′-(butane-1,3-diyne-1,4-diyl)diisophthalic acid (6):

[0060] 4.33g of compound 5 and 4.95g of potassium hydroxide were dissolved in a mixed solvent of 30mL of methanol and 30mL of water and stirred under reflux for 12 hours. After the reaction was completed, 20mL of deionized water was added to dissolve the solid and 2mol L –1 The pH of the solution was adjusted to approximately 2 with HCl until a light yellow precipitate formed. The precipitate was then filtered, washed, and dried to obtain a light yellow solid organic molecular unit 6. Yield: 2.68 g, 7.1 mmol, 81%. 1 H NMR (400MHz, DMSO-d6, ppm): δ = 13.52 (bs, 4H), 8.48 (t, J = 1.2Hz, 2H), 8.35 (d, J = 1.2Hz, 4H); 13 C NMR (100MHz, DMSO-d6, ppm): δ = 166.6, 136.7, 132.8, 131.0, 123.6, 89.8.

[0061] Synthesis of HOF materials:

[0062] To a 20 mL vial, add 30 mg of the tetracarboxylic acid-type organic ligand 5,5′-(butane-1,3-diyne-1,4-diyl)diisophthalic acid and 4 mL of tetrahydrofuran. After sonication, seal the vial with plastic wrap. Then, poke a hole with a needle and place the vial in a 100 mL sealed bottle filled with 30 mL of ethyl acetate. After two weeks of vapor diffusion at 25°C, colorless, transparent needle-shaped crystals were obtained at the bottom of the vial, designated ZJU-HOF-62.

[0063] The resulting homogeneous crystalline material was exchanged multiple times in high-purity acetone using a solvent exchange method, with each exchange interval of at least 3 hours. This was followed by a 3-hour exchange with liquid carbon dioxide, during which the liquid carbon dioxide was discharged for 5 minutes per hour under positive pressure, with the discharge rate of the liquid carbon dioxide always kept below the filling rate. After 3 hours of exhaust and soaking with liquid carbon dioxide, the drying chamber was sealed and the temperature was raised to 40°C. This caused the pressure in the chamber to exceed the critical point of carbon dioxide, 1300 psi. The chamber was maintained above the critical point for 1 hour, and then the chamber was slowly exhausted over 2 hours. Finally, the dried sample was vacuum degassed at 40°C for 12 hours, ultimately obtaining the ZJU-HOF-62 material with the solvent molecules removed.

[0064] Tests on the HOF materials of Example 1 and Example 2:

[0065] The obtained HOF material was subjected to single crystal X-ray diffraction test, and its microscopic crystal structure diagram is shown in Figure 2 , PXRD characterization data see Figure 3 The material is a framework material with an SQL topological network structure and one-dimensional pores. The pores contain abundant electronegative alkynyl sites and carboxylic acid oxygen sites, which can provide a favorable adsorption environment for propane gas and achieve efficient inverse separation of propylene / propane.

[0066] In order to test the specific surface area of ​​the activated alkyne functionalized HOF material, a nitrogen isothermal adsorption test was conducted at 77K. Figure 4 The BET specific surface area of ​​ZJU-HOF-60 is 1056.8m 2 g –1 The BET specific surface area of ​​ZJU-HOF-62 is 1533.8m 2 g –1 .

[0067] In order to characterize the adsorption and performance of alkyne-functionalized HOF materials for propane and propylene, the isothermal adsorption curves of propane and propylene at 298K and 1 bar were tested. Figure 5It can be seen that ZJU-HOF-62 with diacetylene sites exhibits high propane adsorption capacity and excellent propylene / propane inversion separation performance. The isothermal adsorption curves of ZJU-HOF-62 for propane and propylene at three different temperatures (298K, 318K, 338K) and 1 bar were further tested. Figure 6 It can be seen that the ZJU-HOF-62 material can achieve good propylene / propane reverse separation effect at different temperatures.

[0068] In order to verify the repeatability of the high propane adsorption capacity of ZJU-HOF-62, the propane adsorption isotherm curve at 298K and 1 bar was cycled five times. The test results are shown in Figure 7 , there is no obvious loss of adsorption capacity after multiple cycles.

[0069] In order to characterize the inverse separation performance of HOF materials for propylene / propane mixture, the separation selectivity was calculated according to the ideal adsorption solution theory. Figure 8 It can be seen that ZJU-HOF-62 material has excellent separation performance for a 50 / 50 propane / propylene mixture. By regulating the number of acetylenic groups, enhanced propylene / propane inversion separation performance is obtained.

[0070] In order to characterize the recyclability of ZJU-HOF-62 after testing, the PXRD patterns were tested. Figure 9 It can be seen that the structure of the material remains intact after multiple adsorption tests and is recyclable.

[0071] In order to explore the mechanism of ZJU-HOF-62 in achieving efficient propylene / propane reverse separation, DFT calculations were performed to analyze the adsorption sites and host-guest interactions of the material for propylene and propane gas molecules. Figure 10 It can be seen that the abundant diacetylene groups and carboxylic acid oxygen groups in this material can provide more and stronger interaction forces for propane molecules, thereby achieving preferential binding of propane gas.

[0072] In order to simulate the actual industrial separation process, a dynamic penetration test was used to evaluate the actual separation effect of ZJU-HOF-62 on propane / propylene mixture. 1.2108 g of activated sample was filled into the packed column as the fixed bed of the adsorption tower, and then the column was heated at 1.25 mL min –1 The penetration test was conducted by introducing a 50 / 50 propane / propylene mixture at a flow rate of Figure 11 As can be seen from the figure, ZJU-HOF-62 can achieve efficient separation of a 50 / 50 propane / propylene mixture. In order to characterize the recyclability and cyclic stability of the material, multiple cyclic penetration tests were conducted on a 50 / 50 propane / propylene mixture. The results showed that the material had no significant loss in separation ability during the five cycles ( Figure 12 ).

[0073] The above are only some preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an alkynyl-functionalized HOF material for efficient inverse separation of propylene / propane, characterized in that: include: Step 1: Dissolve the tetracarboxylic acid type organic ligand H4L in a benign organic solvent to obtain an H4L solution, which is then placed in a poor solvent vapor atmosphere to obtain the HOF material by a vapor diffusion method; Step 2: After solvent exchange of the HOF material with a low-boiling-point reagent, the solvent molecules in the pores are removed by an activation method to obtain the alkynyl-functionalized HOF material for efficient propylene / propane inverse separation; The tetracarboxylic acid type organic ligand H4L is any one of 5,5′-(ethynyl)diisophthalic acid and 5,5′-(butane-1,3-diyne-1,4-diyl)diisophthalic acid, and their structural formulas correspond to the following:

2. The preparation method according to claim 1, characterized in that The preparation method of the tetracarboxylic acid type organic ligand H4L comprises: First, the ester of H4L functionalized with alkyne was obtained by Sonogashira coupling reaction, which was then hydrolyzed and then the target product H4L was obtained by rotary evaporation, acid addition, filtration and drying.

3. The preparation method according to claim 1, characterized in that In step 1, the benign organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, ethanol, and methanol; and the concentration of the H4L solution is 2-50 mg / mL.

4. The preparation method according to claim 1, characterized in that In step 1, the poor solvent is one or more of diethyl ether, n-hexane, acetone, acetonitrile, dichloromethane, chloroform, ethyl acetate, petroleum ether, and cyclohexane.

5. The preparation method according to claim 1, characterized in that In step 1, the temperature of the gas phase diffusion is 0-50° C.; and the time of the gas phase diffusion is 7-21 days.

6. The preparation method according to claim 1, characterized in that In step 2, the low-boiling-point reagent is one of anhydrous ether, anhydrous n-hexane, high-purity acetone, and high-purity dichloromethane, and the number of solvent exchanges is not less than 8 times, and the interval between each exchange is not less than 3 hours.

7. The preparation method according to claim 1, characterized in that In step 2, the activation method is one or more of supercritical carbon dioxide activation, vacuum decompression, heating or gas purging, and the activation time is 6-48 hours; among them, the supercritical carbon dioxide activation method is to use supercritical carbon dioxide for solvent exchange and then heat, dry and exhaust; the vacuum decompression method is to maintain the vacuum degree of the environment in which the material is located at 0.1-100Pa; the heating method is to maintain the temperature of the environment in which the material is located at 40-60°C; the gas of the gas purging method includes one or more of nitrogen, argon, helium and air.

8. An alkynyl-functionalized HOF material for efficient inverse separation of propylene / propane, characterized in that: The method is prepared by any one of claims 1 to 7.

9. A propane selective adsorbent, characterized in that: Contains the alkyne-functionalized HOF material as claimed in claim 8.

10. Use of the alkyne-functionalized HOF material according to claim 8 in efficient inversion separation of propylene / propane gases.

Images