A solid-state hydrogen storage microporous polymer, its preparation method and application

Abstract

This invention provides a solid-state hydrogen storage microporous polymer, its preparation method, and its application. The method includes the following steps: Step S1, in an inert gas atmosphere, a cobalt source and ligand are dissolved in an alcohol solvent, and a cobalt metal functional building block is prepared through an electrophilic addition reaction; Step S2, in an inert gas atmosphere, the cobalt metal functional building block obtained in Step S1, an alkyne structural building block, and a catalyst are uniformly dispersed in a reaction solvent, and a covalently bonded porous material is prepared through a cross-coupling reaction; Step S3, the porous material obtained in Step S2 is purified to remove unreacted monomers and catalyst, thus preparing a solid-state hydrogen storage microporous polymer. The solid-state hydrogen storage microporous polymer prepared by this invention not only has significant advantages such as excellent porosity, high pressure resistance, extreme high and low temperature resistance, and ideal hydrogen storage capacity, but also possesses windproof, moisture-proof, intrinsically heat-insulating, and flame-retardant properties. The preparation process is simple and the conditions are mild, making it a high-performance, high-safety solid-state hydrogen storage material.

Description

Technical Field

[0001] This invention relates to the field of solid hydrogen storage materials technology, specifically to a solid hydrogen storage microporous polymer, its preparation method, and its application. Background Technology

[0002] In the grand global effort to reduce pollutants and greenhouse gases, the search for clean fuels to replace traditional carbon-based fossil fuels has become an urgent priority, as pressing as an arrow on a bowstring. Hydrogen (H2) is abundant, renewable, and has zero carbon emissions. Its gravimetric energy density (142 MJ / kg) is higher than any other known hydrocarbon fuel, making it a promising clean energy carrier for promoting future economic development. However, the widespread use of hydrogen fuel is limited by the lack of efficient, safe, and economical storage systems. Currently, many hydrogen storage technologies are under development, including ultra-high pressure storage, cryogenic storage, metal hydrides, chemical hydrogen storage materials, and the emerging adsorption storage based on nanoporous materials. Cryogenic and ultra-high pressure storage require extreme conditions, are costly, and pose significant safety risks, while chemical hydrogen storage materials require additional energy to break chemical bonds and release hydrogen, typically resulting in a slow hydrogen release rate.

[0003] In recent years, with the precise design and rapid development of porous organic polymers, hydrogen storage technology based on porous material adsorption has shown significant advantages, especially in automotive applications. Compared to traditional porous materials such as activated carbon, zeolite, and alumina, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and conjugated microporous polymers (CMPs) have demonstrated more significant advantages. They possess higher specific surface areas, and their pore geometry and volume are adjustable. This unique property makes them highly attractive in gas storage applications, making them a hot research and application topic. Among them, conjugated microporous polymers (CMPs) offer numerous significant advantages in hydrogen storage applications. The unique microporous structure of CMPs not only provides high tunability, allowing precise control of pore size, shape, and distribution to adapt to hydrogen molecule sizes and achieve efficient physical adsorption, but also offers abundant adsorption sites due to their large specific surface area (up to hundreds of square meters per gram), greatly increasing the hydrogen adsorption capacity. CMPs also exhibit good chemical and thermal stability, maintaining structural integrity under complex conditions and ensuring the safety and reliability of the hydrogen storage process. Meanwhile, some CMP materials can have their hydrogen storage performance further improved after chemical modification, giving them broad application prospects and huge development potential in the field of hydrogen energy development and utilization, especially in the efficient storage of hydrogen.

[0004] To improve the hydrogen adsorption performance of existing porous organic polymers, various methods have been employed to modify them, such as impregnation, catalysis, functionalization, and metal doping and coordination. Among these modification methods, metal doping and coordination can alter the surface charge distribution and polarization of porous materials, enhancing the van der Waals forces on hydrogen molecules, thus making it easier for hydrogen to be adsorbed and captured by the porous materials. Simultaneously, metal doping and coordination may also affect the pore structure of porous materials, optimizing pore size distribution and pore volume, providing more suitable adsorption sites for hydrogen molecules, thereby comprehensively improving the adsorption capacity and rate of hydrogen for porous materials. This enhances their hydrogen adsorption performance from multiple dimensions, demonstrating potential application value in fields such as energy storage. Goddard et al. were among the first to conduct theoretical research on hydrogen storage using metal-doped and coordinated MOFs and COFs (JAm Chem Soc, 2008; 130:11580). Their calculations show that metal-doped and coordinated porous materials can meet the 2015 U.S. Department of Energy (DOE) weight targets (i.e., 4.5 wt% and 28 g / L). Da et al. also demonstrated that the H2 absorption rate of metal-doped and coordinated materials is superior to that of the original sample (Angew Chem Int Ed, 2009; 48:4730). In addition to theoretical studies, experimental research on metal-doped and coordinated porous material systems is also underway. Li et al. reported a maximum H2 storage capacity of 6.1 wt% for metal-doped and coordinated conjugated microporous polymers at low temperature and ambient pressure (Angew Chem Int Ed, 2010; 49:3330). Extensive theoretical research and experimental data indicate that introducing metal functional sites into porous material systems can significantly improve their hydrogen storage capacity and adapt to harsh hydrogen storage conditions, representing a novel and efficient microporous polymer modification strategy. Summary of the Invention

[0005] The purpose of this invention is to prepare a solid hydrogen storage microporous polymer with a wide temperature range and high pressure resistance to meet the demand for efficient and safe storage of hydrogen under low temperature and normal pressure conditions.

[0006] To achieve the above objectives, this invention provides a solid hydrogen storage microporous polymer, its preparation method, and its application. This invention prepares a cobalt metal functional building block by directionally inserting cobalt metal sites into a bidentate ligand through an electrophilic addition reaction, which is then linked to an alkyne structural building block. Under the induction of a metal catalyst, a cross-coupling reaction occurs to prepare a porous material connected by strong covalent bonds. Then, unreacted monomers and metal catalysts are removed through various purification techniques to prepare a solid hydrogen storage microporous polymer with a wide pressure resistance and temperature range.

[0007] According to a first aspect of the present invention, a method for preparing a solid hydrogen storage microporous polymer is provided, comprising the following steps: Step S1, preparing a cobalt metal functional building block: in an inert gas atmosphere, a cobalt source and a ligand are fully dissolved in an alcohol solvent, and a cobalt metal functional building block is prepared by heating through an electrophilic addition reaction; Step S2, preparing a covalently bonded porous material: in an inert gas atmosphere, the cobalt metal functional building block obtained in Step S1, an alkyne structural building block, and a metal catalyst are uniformly dispersed in a reaction solvent, and a covalently bonded porous material is prepared by cross-coupling reaction; Step S3, preparing a pressure-resistant, wide-temperature-range microporous polymer: the porous material obtained in Step S2 is purified to remove unreacted monomers and the metal catalyst, thereby preparing a solid hydrogen storage microporous polymer with a pressure resistance and wide temperature range.

[0008] Preferably, the inert gas in steps S1 and S2 is one or more of nitrogen, helium, neon, argon, krypton, and xenon, and the purity of the inert gas is maintained at 99.9% or higher.

[0009] Preferably, in step S1, the cobalt source is one or more of cobalt halide, cobalt sulfate, cobalt nitrate, cobalt carbonate, cobalt oxalate, cobalt oxide, and cobalt hydroxide, and the ligand is 5,5'-dibromo-2,2'-bipyridine, 5,5'-dichloro-2,2'-bipyridine, 6,6'-dibromo-2,2'-bipyridine, 6,6'-dichloro-2,2'-bipyridine, 4,4'-dibromo-2,2'-bipyridine, or 2,6'-dibromo-3 The reaction mixture consists of one or more of 4'-bipyridine and 6,6'-dibromo-2,3'-bipyridine, with a cobalt source to ligand molar ratio of 1:2 to 2:1. The alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and ethylene glycol. The total mass of the cobalt source and ligand accounts for 1 to 5% of the mass of the alcohol solvent. The electrophilic addition reaction is carried out at a temperature of 60 to 90 °C for 12 to 48 hours.

[0010] Preferably, in step S2, the alkyne structural building block is one or more of 1,4-diethynbenzene, 1,3,5-triethynbenzene, 1,3,6,8-tetraethynylpyrene, 2,4,6-tris-4-ethynylphenyl-1,3,5-triazine, and tris-4-ethynylphenylamine, and the molar ratio of the reactive functional groups of the cobalt metal functional building block to the alkyne structural building block is 1:3 to 3:1.

[0011] Preferably, in step S2, the metal catalyst is a mixed solvent of palladium-based catalyst and copper-based catalyst. The palladium-based catalyst is one or more of palladium acetate, palladium chloride, tetraphenylphosphine palladium, tribenzylacetone dipalladium, and palladium on carbon. The copper-based catalyst is one or more of cuprous iodide, cuprous bromide, cuprous chloride, copper acetate, copper sulfate, and nano-copper catalyst. The molar ratio of palladium-based catalyst to copper-based catalyst in the metal catalyst is 1:5 to 1:20.

[0012] Preferably, in step S2, the reaction solvent is one or more of the following non-alkaline solvents (toluene, N,N-dimethylformamide, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, N-methylpyrrolidone, 1,4-dioxane) mixed with triethylamine, the volume ratio of the non-alkaline solvent to triethylamine is 1:6 to 6:1, the total molar concentration of cobalt metal functional building blocks and acetylene structural building blocks is 1 to 30% of the reaction solvent, the reaction temperature of the cross-coupling reaction is 50 to 110°C, and the reaction time is 12 to 72 hours.

[0013] Preferably, the purification technique in step S3 is one or more of Soxhlet extraction, supercritical fluid extraction, dialysis, column chromatography, solvent displacement, and ultrasonic cleaning. The solvent used in the above purification techniques is one or more of dichloromethane, chloroform, acetone, deionized water, methanol, tetrahydrofuran, and pyridine. The purification purity is less than 1‰ of impurities.

[0014] Preferably, the purification technique in step S3 is Soxhlet extraction, with an extraction temperature of 60–100°C, an extraction time of 6–12 h, and an extraction solvent of a mixture of dichloromethane, methanol, and acetone. The volume ratio of the covalently bonded porous material to the extraction solvent is 1:5 to 1:50.

[0015] Preferably, the purification technique in step S3 is supercritical fluid extraction, with an extraction temperature of 60–100°C, an extraction time of 6–12 h, and an extraction solvent of a mixture of dichloromethane, methanol, and acetone. The volume ratio of the covalently bonded porous material to the extraction solvent is 1:5 to 1:50.

[0016] Preferably, the purification technique in step S3 is dialysis, with a dialysis temperature of 0–25°C, a dialysis time of 8–48 h, and a dialysis solution that is a mixed solvent of dichloromethane, methanol, and acetone. The volume ratio of the covalently bonded porous material to the dialysis solution is 1:5 to 1:50.

[0017] Preferably, the purification technique in step S3 is solvent replacement method, with a replacement temperature of 0-80℃, a replacement time of 1-48h, a stirring speed of 50-500rpm, and a mixed solvent of dichloromethane, methanol and acetone. The volume ratio of the covalently bonded porous material to the replacement solvent is 1:5 to 1:50.

[0018] To achieve the above objectives, according to a second aspect of the present invention, the present invention also provides a microporous polymer obtained by the aforementioned preparation method.

[0019] Preferably, the obtained microporous polymer has a high specific surface area (377m²). 2 / g~462m 2It has small pore size (0.56nm~0.92nm), abundant cobalt content (3.1~3.6wt%) and ideal hydrogen storage capacity (hydrogen adsorption capacity higher than 5.1wt%).

[0020] To achieve the above objectives, according to a third aspect of the present invention, the present invention also provides the application of the above-described microporous polymer in solid hydrogen storage materials.

[0021] The beneficial effects of this invention are as follows: (1) The introduction of cobalt metal sites changes the molecular skeleton structure, causing the pore size to shrink, providing a larger specific surface area and a wider pore volume for hydrogen adsorption and storage; (2) The introduction of heteroatoms such as nitrogen and cobalt can change the surface charge distribution of the molecular skeleton, causing the molecular polarity to change, generating more intermolecular forces for the hydrogen adsorption process; (3) The conjugated microporous polymer has excellent chemical stability and environmental tolerance, enabling the adsorbent to maintain the skeleton and structure stability under low temperature or high pressure conditions, meeting the process environment for hydrogen adsorption and storage; (4) The steps work together to prepare a material that not only has a series of advantages such as excellent pore properties, high pressure resistance, extreme high and low temperature resistance, and ideal hydrogen storage capacity, but also has windproof, moisture-proof and intrinsic heat insulation and flame retardant properties. The preparation process is simple and the conditions are mild, making it a highly promising and high-performance safe solid hydrogen storage material.

[0022] The technical solution proposed in this invention enables a pressure-resistant, wide-temperature-range, high-safety solid-state hydrogen storage microporous polymer to possess high specific surface area, small pore size, abundant cobalt metal adsorption sites, and ideal hydrogen adsorption capacity. This material is designed to meet the demand for efficient and safe hydrogen storage under low-temperature and ambient-pressure conditions, and has broad application potential and market prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 1.

[0025] Figure 2 This is an elemental mapping image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 1.

[0026] Figure 3 This is the Fourier transform infrared spectrum of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 1.

[0027] Figure 4 This is the powder X-ray diffraction spectrum of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 1.

[0028] Figure 5 This is a nitrogen adsorption-desorption isotherm curve of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 1.

[0029] Figure 6 This is a scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 2.

[0030] Figure 7 This is an elemental mapping image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 2.

[0031] Figure 8 This is a scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 3.

[0032] Figure 9 This is an elemental mapping image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 3.

[0033] Figure 10 This is a scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 4.

[0034] Figure 11 This is an elemental mapping image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer in Example 4.

[0035] Figure 12 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the embodiments.

[0037] like Figure 12As shown, Example 1 of the present invention provides a method for preparing a solid hydrogen storage microporous polymer, comprising the following steps: Step S11, preparing cobalt metal functional building blocks: under argon atmosphere, cobalt halide and 5,5'-dibromo-2,2'-bipyridine (molar ratio 1:1) are fully dissolved in anhydrous ethanol solution (the total mass of cobalt source and ligand accounts for 3% of the mass of anhydrous ethanol), the temperature is raised to 85°C, and the reaction is carried out for 24 hours to prepare cobalt metal functional building blocks through electrophilic addition reaction; Step S12, preparing covalently bonded porous materials: the cobalt metal functional building blocks prepared in step S11 are combined with 1,3,5-triethynylbenzene (functional group molar ratio 1:1), tetrakis(triphenylphosphine)palladium and cuprous iodide (molar ratio 1:1). 10) Dispersed in a mixed solvent of N,N-dimethylformamide and triethylamine (volume ratio 2:1), reacted at 90°C under nitrogen atmosphere for 72 hours to prepare a covalently bonded porous material; Step S13, preparation of a pressure-resistant, wide-temperature-range microporous polymer: The covalently bonded porous material obtained in step S12 is purified by Soxhlet extraction (extraction temperature 80°C, extraction time 10 h, extraction solvent is a mixed solvent of dichloromethane, methanol and acetone, volume ratio of covalently bonded porous material to extraction solvent is 1:30) to remove unreacted monomers and metal catalysts, preparing a solid hydrogen storage microporous polymer with excellent pore properties, high pressure resistance, and resistance to extreme high and low temperatures, with a specific surface area of ​​462 m². 2 / g, with an average pore size of 0.56nm.

[0038] like Figure 1 As shown in the scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer obtained in Example 1 of the present invention, the material has a randomly arranged and stacked spherical morphology.

[0039] like Figure 2 As shown in the elemental mapping diagram of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 1 of the present invention, carbon, nitrogen and cobalt elements are uniformly distributed on the surface of the material, and the cobalt element content is 3.6 wt%.

[0040] like Figure 3 As shown, the Fourier transform infrared spectrum of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 1 of the present invention indicates that the material structure contains C=N stretching vibration, terminal alkyne (-C≡CH) stretching vibration, and C=C and C≡C stretching vibration.

[0041] like Figure 4 As shown, the powder X-ray diffraction pattern of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer obtained in Example 1 of the present invention shows an amorphous diffraction peak (20°) representing the conjugated microporous polymer, indicating that the material has an amorphous structure under kinetic control.

[0042] like Figure 5As shown, the nitrogen adsorption-desorption isotherm curve of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 1 of the present invention indicates that the material has excellent specific surface area and narrow pore size.

[0043] Example 2 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, comprising the following steps: Step S21, preparing cobalt metal functional building blocks: Under an argon atmosphere, cobalt nitrate and 5,5'-dichloro-2,2'-bipyridine (molar ratio 1:2) are fully dissolved in anhydrous methanol solution (the total mass of cobalt source and ligand accounts for 5% of the mass of anhydrous methanol), the temperature is raised to 60°C, and the reaction is carried out for 48 hours, thereby preparing cobalt metal functional building blocks through an electrophilic addition reaction; Step S22, preparing covalently bonded porous materials: The cobalt metal functional building blocks prepared in step S21 are combined with 1,4-diacetylenebenzene (functional group molar ratio 3:2), tris(dibenzylacetone)palladium and cuprous bromide (molar ratio 1:2). A covalently bonded porous material was prepared by dispersing a mixture of dichloromethane and triethylamine (volume ratio 2:1) in a 1:5 ratio at 100°C under nitrogen atmosphere for 60 hours. Step S23: Preparation of a pressure-resistant, wide-temperature-range microporous polymer: The covalently bonded porous material obtained in step S22 was purified by supercritical fluid extraction (extraction temperature 90°C, extraction time 8 hours, extraction solvent a mixture of dichloromethane, methanol, and acetone, volume ratio of covalently bonded porous material to extraction solvent 1:20) to remove unreacted monomers and metal catalysts, thus preparing a solid-state hydrogen storage microporous polymer with excellent pore properties, high pressure resistance, and tolerance to extreme high and low temperatures, with a specific surface area of ​​424 m². 2 / g, with an average pore size of 0.71nm.

[0044] like Figure 6 As shown in the scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer obtained in Example 2 of the present invention, the material has a randomly arranged and stacked spherical morphology.

[0045] like Figure 7 As shown in the elemental mapping diagram of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 2 of the present invention, carbon, nitrogen and cobalt elements are uniformly distributed on the surface of the material, and the cobalt element content is 3.1 wt%.

[0046] Example 3 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, comprising the following steps: Step S31, preparing cobalt metal functional building blocks: under argon atmosphere, cobalt carbonate and 6,6'-dibromo-2,2'-bipyridine (molar ratio 2:1) are fully dissolved in anhydrous n-propanol solution (the total mass of cobalt source and ligand accounts for 1% of the mass of anhydrous n-propanol), the temperature is raised to 90°C, and the reaction is carried out for 12 hours, thereby preparing cobalt metal functional building blocks through electrophilic addition reaction; Step S32, preparing covalently bonded porous materials: the cobalt metal functional building blocks prepared in step S31 are combined with 1,3,6,8-tetraethynylpyrene (functional group molar ratio 2:1), palladium acetate and copper acetate (molar ratio 1:1). :15) Dispersed in a mixed solvent of 1,2-dichloroethane and triethylamine (volume ratio 3:2), reacted at 85°C under nitrogen atmosphere for 60 hours to prepare a covalently bonded porous material; Step S33, preparation of a pressure-resistant, wide-temperature-range microporous polymer: The covalently bonded porous material obtained in step S32 was purified by dialysis (dialysis temperature 10°C, dialysis time 24h, dialysis solution a mixed solvent of dichloromethane, methanol and acetone, volume ratio of covalently bonded porous material to dialysis solution 1:40) to remove unreacted monomers and metal catalysts, preparing a solid hydrogen storage microporous polymer with excellent pore properties, high pressure resistance, and resistance to extreme high and low temperatures, with a specific surface area of ​​389 m². 2 / g, with an average pore size of 0.88nm.

[0047] like Figure 8 As shown in the scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer obtained in Example 3 of the present invention, the material has a randomly arranged and stacked spherical morphology.

[0048] like Figure 9 As shown in the elemental mapping diagram of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 3 of the present invention, carbon, nitrogen and cobalt elements are uniformly distributed on the surface of the material, and the cobalt element content is 3.2 wt%.

[0049] Example 4 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, comprising the following steps: Step S41, preparing cobalt metal functional building blocks: under argon atmosphere, cobalt sulfate and 6,6'-dichloro-2,2'-bipyridine (molar ratio 3:2) are fully dissolved in anhydrous ethylene glycol solution (the total mass of cobalt source and ligand accounts for 4% of the mass of anhydrous ethylene glycol), the temperature is raised to 80°C, and the reaction is carried out for 36 hours to prepare cobalt metal functional building blocks through electrophilic addition reaction; Step S42, preparing covalently bonded porous materials: the cobalt metal functional building blocks prepared in step S41 are combined with tris(4-acetylenylphenylamine) (functional group molar ratio 1:1), tris(dibenzylacetone dipalladium) and copper sulfate (molar ratio 1:12) in a mixture. A covalently bonded porous material was prepared by reacting the covalently bonded porous material in a mixed solvent of tetrahydrofuran and triethylamine (volume ratio 1:2) at 80°C under nitrogen atmosphere for 48 hours. Step S43 involves preparing a pressure-resistant, wide-temperature-range microporous polymer: the covalently bonded porous material obtained in step S42 is purified by solvent displacement (displacement temperature 40°C, displacement time 48 hours, stirring speed 500 rpm, displacement solvent a mixed solvent of dichloromethane, methanol, and acetone, volume ratio of covalently bonded porous material to displacement solvent 1:50) to remove unreacted monomers and metal catalysts, thus preparing a solid-state hydrogen storage microporous polymer with excellent pore properties, high pressure resistance, and tolerance to extreme high and low temperatures, with a specific surface area of ​​377 m². 2 / g, with an average pore size of 0.92nm.

[0050] like Figure 10 As shown in the scanning electron microscope image of the pressure-resistant, wide-temperature-range hydrogen storage microporous polymer obtained in Example 4 of the present invention, the material has a randomly arranged and stacked spherical morphology.

[0051] like Figure 11 As shown in the elemental mapping diagram of the pressure-resistant wide-temperature-range hydrogen storage microporous polymer obtained in Example 4 of the present invention, carbon, nitrogen and cobalt elements are uniformly distributed on the surface of the material, and the cobalt element content is 3.0 wt%.

[0052] Comparative Example 1 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, which basically adopts the method of Example 1 to prepare a pressure-resistant, wide-temperature-range, high-safety solid hydrogen storage microporous polymer. The difference is that this example does not use cobalt metal as a functional building block to combine with the acetylene structural building block to prepare the porous polymer. Specifically, 5,5'-dibromo-2,2'-bipyridine and 1,3,5-triethynylbenzene (functional group molar ratio 1:1), tetratetraphenylphosphine palladium and cuprous iodide (molar ratio 1:10) were dispersed in a mixed solvent of N,N-dimethylformamide and triethylamine (volume ratio 2:1). The reaction was carried out under nitrogen atmosphere at 90°C for 72 hours to prepare a covalently linked porous material. The obtained covalently linked porous material was purified by Soxhlet extraction (extraction temperature 80°C, extraction time 10 h, extraction solvent a mixed solvent of dichloromethane, methanol, and acetone, volume ratio of covalently linked porous material to extraction solvent 1:30) to remove unreacted monomers and metal catalysts, preparing a metal-free porous polymer with a specific surface area of ​​156 m². 2 / g, with an average pore size of 2.58nm.

[0053] Comparative Example 2 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, which basically adopts the method of Example 3 to prepare a pressure-resistant, wide-temperature-range, high-safety solid hydrogen storage microporous polymer. The difference is that this example does not use purification techniques to treat covalently bonded porous materials to prepare the microporous polymer. Specifically, under argon atmosphere, cobalt carbonate and 6,6'-dibromo-2,2'-bipyridine (molar ratio 2:1) were fully dissolved in anhydrous n-propanol solution (the total mass of cobalt source and ligand accounted for 1% of the mass of anhydrous n-propanol). The temperature was raised to 90℃ and the reaction was carried out for 12 hours to prepare cobalt metal functional building blocks via electrophilic addition reaction. The prepared cobalt metal functional building blocks, 1,3,6,8-tetraethynylpyrene (functional group molar ratio 2:1), palladium acetate, and copper acetate (molar ratio 1:15) were dispersed in a mixed solvent composed of 1,2-dichloroethane and triethylamine (volume ratio 3:2). Under nitrogen atmosphere, the reaction was carried out at 85℃ for 60 hours to prepare a pressure-resistant, wide-temperature-range microporous polymer with a specific surface area of ​​189 m². 2 / g, with an average pore size of 2.28nm.

[0054] Comparative Example 3 of this invention provides a method for preparing a solid hydrogen storage microporous polymer, which basically adopts the method of Example 2 to prepare a pressure-resistant, wide-temperature-range, high-safety solid hydrogen storage microporous polymer. The difference is that this example uses phenanthroline-based ligands to prepare cobalt metal functional building blocks, which are then linked with alkyne structural building blocks to prepare the microporous polymer. Specifically, under an argon atmosphere, cobalt nitrate and a solution of 3,8-dibromo-1,10-phenanthroline-5,6-dione (molar ratio 1:2) are fully dissolved in anhydrous methanol solution (the total mass of the cobalt source and ligand is 5% of the mass of anhydrous methanol). The temperature is raised to 60°C, and the reaction is carried out for 48 hours to prepare the cobalt metal functional building block via an electrophilic addition reaction. The cobalt metal functional building block, 1,4-diacetylenebenzene (functional group molar ratio 3:2), tris(dibenzylacetone)palladium and cuprous bromide (molar ratio 1:5) are dispersed in a solution of dichloromethane and triethylamine (volume ratio 1:1). In a mixed solvent of 2:1, under nitrogen atmosphere, at 100℃, a covalently bonded porous material was prepared for 60 hours. The obtained covalently bonded porous material was then purified by supercritical fluid extraction (extraction temperature 90℃, extraction time 8 h, extraction solvent a mixed solvent of dichloromethane, methanol, and acetone, with a volume ratio of covalently bonded porous material to extraction solvent of 1:20) to remove unreacted monomers and metal catalysts, thus preparing a solid-state hydrogen storage microporous polymer with excellent pore properties, high pressure resistance, and tolerance to extreme high and low temperatures, possessing a specific surface area of ​​164 m². 2 / g, with an average pore size of 2.03nm.

[0055] The structural characterization and performance testing are as follows.

[0056] Scanning electron microscopy observation: The microstructure of the high-safety solid-state hydrogen storage microporous polymer was observed using a field emission scanning electron microscope (model JSM-7900F, NEC). Figure 1 , Figure 6 , Figure 8 , Figure 10 ).

[0057] Surface elemental distribution testing: The surface elemental distribution of the high-safety solid-state hydrogen storage microporous polymer was recorded using an energy-dispersive X-ray spectrometer (Vario EL, NEC). Figure 2 , Figure 7 , Figure 9 , Figure 11 ).

[0058] Functional group structure testing: The functional groups of the high-safety solid-state hydrogen storage microporous polymer were recorded using an infrared spectrometer (model VERTEX 70, Bruker, USA). Figure 3 ).

[0059] Crystal structure testing: The crystal structure of the high-safety solid-state hydrogen storage microporous polymer was recorded using an X-ray spectrometer (model D / Max-2400, Rigaku Corporation, Japan). Figure 4 ).

[0060] Specific surface area test: The nitrogen adsorption-desorption isotherm of the high-safety solid hydrogen storage microporous polymer was measured at 77K using a gas adsorption analyzer (ASAP 2060, Micromeritics, USA). Figure 5 ).

[0061] Hydrogen storage performance testing: Using a commercial pressure-composition-isotherm (PCI) apparatus, the low hydrogen adsorption isotherm of the high-safety solid-state hydrogen storage microporous polymer was tested by volumetric method at 77 K and a pressure range of 0–1 bar. High-purity hydrogen (99.999%) was used as the adsorbent in the experiment.

[0062] Experimental results: such as Figure 1 , Figure 6 , Figure 8 and Figure 10 As shown, under the induction of a metal catalyst, cobalt metal functional building blocks and alkyne structural building blocks undergo a cross-coupling reaction to form a high-pressure-resistant, wide-temperature-range, high-safety solid-state hydrogen storage microporous polymer. Differences in the structures of the reacting monomers, the polarity of the reaction solvent, and the purification techniques all affect the microstructure and pore properties. The polymer exhibits a regular, disordered spherical structure without significant agglomeration, greatly improving the specific surface area and pore properties of the microporous polymer and fully exposing the active centers.

[0063] like Figure 2 , Figure 7 , Figure 9 and Figure 11 As shown, carbon, nitrogen, and cobalt elements are uniformly distributed on the surface of the microporous polymer, indicating that the cobalt metal functional building blocks and the acetylene structural building blocks are fully connected, and finally a uniform and compact solid hydrogen storage microporous polymer with a wide temperature range and high safety is grown. The cobalt adsorption sites are uniformly anchored on the material surface, providing more opportunities and possibilities for hydrogen adsorption.

[0064] like Figure 3 As shown, the signals corresponding to C≡CH and C-Br bonds disappear, indicating that the coupling reaction has occurred completely. At 3082 and 804 cm⁻¹, the signals disappeared. -1 The signal observed at approximately 2200 cm corresponds to the stretching and bending vibrations of the CH bonds within the benzene ring; at approximately 2200 cm -1 The signal observed at 1600 cm can be attributed to the stretching vibration of the -C≡C- bond; -1 and 1400cm -1The strong and broad peaks observed nearby are attributed to skeletal vibrations of the benzene ring backbone. The appearance of these characteristic signal peaks indicates the successful preparation of the microporous polymer.

[0065] like Figure 4 As shown, the diffraction pattern of the microporous polymer shows a broad and flat signal peak at around 20°, indicating that the microporous polymer is formed in an amorphous structure under kinetic control.

[0066] like Figure 5 As shown, the adsorption-desorption isotherms of the adsorbent exhibit a significant increase in nitrogen adsorption in the low-pressure region, a relatively slow increase in the medium-pressure region, and a sharp increase in the high-pressure region, indicating that the adsorbent is composed of continuous micropores, mesopores, and macropores.

[0067] Table 1 compares the specific surface area, average pore size, cobalt content, and hydrogen adsorption capacity of the high-safety solid hydrogen storage microporous polymers obtained in the examples and comparative examples.

[0068] Table 1

[0069]

[0070] Examples 1-4 have a high specific surface area (377m²). 2 / g~462m 2 The cobalt metal adsorption sites exhibit a small pore size (0.56 nm–0.92 nm) and a relatively small pore size. This is because the directional anchoring of the cobalt metal adsorption sites on the bidentate ligand alters the molecular framework structure, thereby reducing the pore size. The specific surface areas of Comparative Examples 1–3 are only 156–189 m². 2 / g, with an average pore size of 2.03–2.58 nm, which is due to defects in pore structure and functional groups caused by the lack of use of metal groups and purification techniques.

[0071] The hydrogen storage capacity of pressure-resistant, wide-temperature-range microporous polymers is closely related to their specific surface area, pore size, and metal adsorption sites. Examples 1-4, which possess a large specific surface area, small pore size, and abundant cobalt adsorption sites, all exhibit hydrogen adsorption capacities exceeding 5.1 wt%, demonstrating excellent hydrogen storage capacity. Among them, Example 1, with the highest specific surface area, smallest pore size, and most cobalt adsorption sites, performed the best in the hydrogen storage test, with a hydrogen adsorption capacity of 6.2 wt%, significantly higher than Comparative Example 1 (1.5 wt%), which has a low specific surface area, large pore size, and no cobalt adsorption sites.

[0072] This invention provides a solid hydrogen storage microporous polymer, its preparation method, and its application. Many methods and approaches exist to achieve this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for preparing a solid-state hydrogen storage microporous polymer, characterized in that, The method comprises the following steps: Step S1, dissolving a cobalt source and a ligand in an alcohol solvent in an inert gas atmosphere to prepare a cobalt metal functional block by reaction; Step S2, dispersing the cobalt metal functional block obtained in step S1, an alkyne structure block and a metal catalyst in a reaction solvent in an inert gas atmosphere to prepare a covalently linked porous material by cross-coupling reaction; Step S3, removing unreacted monomers and metal catalysts from the covalently linked porous material obtained in step S2 by purification technology to prepare a solid-state hydrogen storage microporous polymer. In step S1, the cobalt source is one or more of cobalt halide, cobalt sulfate and cobalt nitrate, the ligand is one or more of 5,5'-dibromo-2,2'-bipyridine, 5,5'-dichloro-2,2'-bipyridine, 6,6'-dibromo-2,2'-bipyridine, 6,6'-dichloro-2,2'-bipyridine, 4,4'-dibromo-2,2'-bipyridine, 2,6'-dibromo-3,4'-bipyridine and 6,6'-dibromo-2,3'-bipyridine, the reaction temperature is 60-90℃, and the reaction time is 12-48 hours. In step S2, the alkyne structure block is one or more of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene, 1,3,6,8-tetraethynylpyrene, 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine and tris(4-ethynylphenyl)amine.

2. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, In steps S1 and S2, the inert gas is one or more of nitrogen, helium, neon, argon, krypton and xenon, and the purity of the inert gas is kept above 99.9%.

3. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, The alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and ethylene glycol, the molar ratio of the cobalt source to the ligand is 1:2-2:1, and the total mass of the cobalt source and the ligand accounts for 1-5% of the mass of the alcohol solvent.

4. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, The reaction functional group molar ratio of the cobalt metal functional block to the alkyne structure block is 1:3-3:

1.

5. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, In step S2, the metal catalyst is a mixed solvent of a palladium-based catalyst and a copper-based catalyst, the palladium-based catalyst is one or more of palladium acetate, palladium chloride, tetrakis(triphenylphosphine)palladium, tris(dibenzylideneacetone)dipalladium and palladium-carbon catalyst, the copper-based catalyst is one or more of cuprous iodide, cuprous bromide, copper chloride, copper acetate, copper sulfate and nano copper catalyst, and the molar ratio of the palladium-based catalyst to the copper-based catalyst in the metal catalyst is 1:5-1:

20.

6. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, In step S2, the reaction solvent is a mixed solvent of a non-basic solvent and triethylamine, the non-basic solvent is one or more of toluene, N,N-dimethylformamide, 1,2-dichloroethane, dichloromethane, tetrahydrofuran and N-methylpyrrolidone, the volume ratio of the non-basic solvent to triethylamine is 1:6-6:1, the substance amount concentration between the sum of the cobalt metal functional block and the alkyne structure block and the reaction solvent is 1-30%, the cross-coupling reaction temperature is 50-110℃, and the reaction time is 12-72 hours.

7. The method for preparing the solid hydrogen storage microporous polymer as described in claim 1, characterized in that, The purification technique in the step S3 is one or more of the following: Soxhlet extraction, supercritical fluid extraction, dialysis, column chromatography, solvent displacement, ultrasonic cleaning, and the solvent used in the purification technique is one or more of the following: dichloromethane, chloroform, acetone, deionized water, methanol, tetrahydrofuran, and pyridine, and the impurity of the purified product is less than 1 ‰.

8. A microporous polymer prepared by the method of claim 1.

9. The microporous polymer of claim 8, wherein, The specific surface area is 377 m 2 / g ~ 462 m 2 / g, the pore size is 0.56 nm ~ 0.92 nm, the cobalt element content is 3.1 ~ 3.6 wt%, and the hydrogen adsorption amount is ≥ 5.1 wt%.

10. The microporous polymer of claim 9 for use in solid-state hydrogen storage material.

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