A three-dimensional boron nitride foam loaded organic covalent framework hydrogen storage material and a preparation method thereof

Abstract

The application discloses a three-dimensional boron nitride foam loaded organic covalent framework hydrogen storage material and a preparation method thereof. A three-dimensional porous boron nitride foam is prepared through an in-situ template-free foaming reaction with ammonia borane and thiourea. The thiourea is used as a foaming agent in the synthesis, and the foaming obtains the three-dimensional structure boron nitride foam with thin walls. The product has a hierarchical porous structure, and the open-cell and high-porosity ultralight three-dimensional foam is beneficial to the permeation of gas, has excellent adsorption characteristics and cycle performance. The loaded melamine terephthaldehyde copolymerized organic covalent framework also has a high specific surface area, can synergistically adsorb and store hydrogen through pores, and obtains the final three-dimensional boron nitride foam loaded organic covalent framework hydrogen storage material with high hydrogen storage density. The three-dimensional boron nitride foam loaded organic covalent framework hydrogen storage material prepared by the application has the characteristics of rapid hydrogen adsorption rate, and improves chemical stability, mechanical performance and thermal stability, and can be applied to new energy hydrogen storage key materials.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials, specifically relating to a three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material and its preparation method. Background Technology

[0002] Hydrogen possesses advantages such as abundant reserves, high energy density, zero emissions, and low cost, making it a promising new energy carrier. Hydrogen storage is a crucial step in hydrogen utilization. The storage and release of hydrogen involves molecular adsorption, diffusion, chemical bonding, van der Waals forces, and dissociation; it can be adsorbed onto suitable material surfaces in molecular or ionic form. Physical adsorption of hydrogen preserves its molecular properties. Currently, the most widely studied materials are porous materials, such as carbon materials (fullerenes, nanotubes, and graphene), zeolites, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), microporous metal coordination materials (MMOMs), and organometallic transition metal complexes.

[0003] Ultralight three-dimensional foams with open pores and high porosity facilitate gas permeation, exhibiting rapid adsorption and excellent circulation performance. Their superior gas adsorption properties and good mechanical properties have attracted increasing attention as hydrogen storage materials. Among them, boron nitride (BN) foam, with its hexagonal crystal structure, high thermal stability, high porosity, and large specific surface area, is a reliable adsorbent suitable for a wide range of applications. Furthermore, the numerous functional groups (such as amino and hydroxyl groups) on BN foam possess high reactivity, which is also beneficial for hydrogen adsorption. These characteristics all indicate that using foamed BN adsorbents can effectively capture and reversibly store hydrogen.

[0004] Furthermore, by incorporating two-dimensional materials such as covalent organic frameworks (COFs) into three-dimensional porous foams, leveraging their high surface area, tunable pore size distribution, and multifunctionality, the regular pore size and high specific surface area of ​​these materials can provide convenient channels for hydrogen adsorption, facilitating higher-density hydrogen storage. The two-dimensional nanostructures within the COF generate high internal connectivity, allowing for effective hydrogen permeation within the foam. Patent application 202210273075.1 discloses a MoS-2 / Ce-doped zirconium-based metal-organic framework composite hydrogen storage material. This material uses a zirconium-based metal-organic framework with high specific area and high porosity as a matrix. Through the synergistic catalysis of cerium and molybdenum disulfide doping, it not only improves the hydrogen storage capacity of the composite material but also enhances its hydrogen adsorption / desorption rate.

[0005] Although BN three-dimensional porous foam materials can maintain their macroscopic structural integrity during hydrogen adsorption and desorption, have a high specific surface area, and exhibit high hydrogen storage performance under environmental conditions, showing great application potential in key components of actual hydrogen storage, these foam materials also have shortcomings such as complex preparation processes, which to some extent limit the further application of these materials. Simplifying the preparation process of three-dimensional foam is also an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material and its preparation method.

[0007] The three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material is not only lightweight but also possesses abundant microporous and mesoporous structures. The supported two-dimensional organic framework penetrates the foam thin wall, synergistically enhancing hydrogen capture and storage capabilities. The foam exhibits excellent hydrogen adsorption capacity, as well as superior mechanical properties, regeneration, and recyclability. Its preparation can be achieved simply by heating the raw materials together with a blowing agent. The developed three-dimensional boron nitride foam-supported organic covalent framework material shows promising practical applications in hydrogen adsorption and storage and can be prepared on a large scale.

[0008] The present invention proposes a method for preparing a three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material, the specific steps of which are as follows: (1) Dissolve amine monomer A in solvent D, then gradually add an aqueous solution of catalyst E to D, and sequentially add a dichloromethane solution of aldehyde monomer B. Place the solution in a high-pressure tube and heat to 100-130°C. o Reaction C, reaction time is 12h~240h, product is collected by ultrasound and washed with solvent acetone; solvent D is dichloromethane or hexane oxide, catalyst E is trifluoromethanesulfonic acid, acetic acid, oxalic acid, citric acid or methylbenzenesulfonic acid. (2) Three-dimensional boron nitride foam is produced by gas foaming. A mixture of 100-400 mg of ammonia borane and 50-100 mg of thiourea in an alumina crucible is heated to 600-800 °C at a heating rate of 5-10 °C per minute. The entire reaction is protected by a gas flow of N2. The reaction is maintained at 600-800 °C for 2-8 hours until it is complete. After cooling to room temperature, the three-dimensional boron nitride foam is collected. (3) The product obtained in step (1) is impregnated with polystyrene binder in a certain mass ratio into the three-dimensional boron nitride foam obtained in step (2). After impregnation at room temperature for 12-24 hours, it is dried at 60-80℃ to obtain the final product.

[0009] In this invention, amine monomer A is melamine or p-phenylenediamine, and aldehyde monomer B is terephthalaldehyde or 1,3,5-tricarboxymethyl-m-phenylene.

[0010] A three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material and its preparation thereof, characterized in that: a covalent organic framework with a periodically repeating structure is obtained by polycondensation reaction of amine monomer A and aldehyde monomer B as raw materials, and in-situ supported in a three-dimensional boron nitride foam, with a loading ratio of 5wt% to 20wt%; the surface area of ​​the covalent organic framework is 700~1000 m². 2 / g, with a pore size of 0.5~1nm; the surface area of ​​the three-dimensional boron nitride foam is 800~1000 m². 2 / g, with a pore size of 2~10um; this high hydrogen storage density three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material exhibits efficient hydrogen adsorption capacity and can be applied to key components of solid-state hydrogen storage.

[0011] This invention addresses the high hydrogen storage density characteristics of hydrogen storage materials by ingeniously designing a three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material. It provides a simple, one-step, template-free method for preparing agent-assisted gas-foamed three-dimensional boron nitride foam. The resulting porous boron nitride foam with ultrathin bubble walls exhibits extremely high gas adsorption capacity. This simple and efficient synthesis method for three-dimensional porous boron nitride foam shows great potential as a high-performance hydrogen storage material.

[0012] Compared with existing technologies, the advantages of this invention are as follows: The preparation method provided by this invention uses widely available raw materials, and the boron nitride, foaming agent, binder, and solvent used can all be industrially produced. The synthesis method is simple and easy to implement. The synthesized three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material can store a large amount of hydrogen, while simplifying the reaction process and improving processability. The three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material can be successfully prepared on a large scale and practically applied in solid-state hydrogen storage new energy systems. Attached Figure Description

[0013] Figure 1 Example 1: Hydrogen adsorption rate diagram of an organic covalent framework hydrogen storage material supported by three-dimensional boron nitride foam. Detailed Implementation

[0014] The following embodiments are further illustrations of the present invention, but are not intended to limit the scope of the invention.

[0015] Example 1: (1) Dissolve 1g of melamine in 100ml of dichloromethane, then gradually add an aqueous solution of acetic acid as a catalyst to the dichloromethane, and then add a dichloromethane solution of terephthalaldehyde in sequence. The mixture is placed in a high-pressure tube and reacted at 100℃ for 12 hours. The product is collected by ultrasound and washed with acetone. (2) Three-dimensional boron nitride foam was produced by gas foaming. A mixture of 100 mg ammonia borane and 50 mg thiourea in an alumina crucible was heated to 600 °C at a heating rate of 5 °C per minute. The entire reaction was protected by a gas flow of N2. The reaction was maintained at 600 °C for 2 hours until it was complete. After cooling to room temperature, the three-dimensional boron nitride foam was collected. (3) The product obtained in step (1) is impregnated with 5 wt% polystyrene binder into the three-dimensional boron nitride foam obtained in step (2). The impregnation is carried out at room temperature for 12 h and then dried at 60 °C for 24 h to obtain the final product. The yield of the composite product is 40-45%.

[0016] The test results for this embodiment are shown below. Figure 1 The horizontal axis represents time in seconds, and the vertical axis represents adsorption rate in wt%. wt% is the weight percentage, and the hydrogen adsorption rate reaches 7%, achieving high-efficiency solid-state hydrogen storage density.

[0017] Example 2: (1) Dissolve 1.2g of melamine in 100ml of solvent epoxide, then gradually add an aqueous solution of the catalyst trifluoromethanesulfonic acid to the epoxide, and sequentially add a dichloromethane solution of aldehyde monomer B. Then, place the solution in a high-pressure tube and heat to 110°C. o C reaction, reaction time 24h, product collected by ultrasound, and washed with acetone solvent; (2) Three-dimensional boron nitride foam was produced by gas foaming. A mixture of 150 mg ammonia borane and 60 mg thiourea in an alumina crucible was heated to 650 °C at a heating rate of 6 °C per minute. The entire reaction was protected by a gas flow of N2. The reaction was maintained at 650 °C for 3 hours until it was complete. After cooling to room temperature, the three-dimensional boron nitride foam was collected. (3) The product obtained in step (1) was impregnated with 10 wt% polystyrene binder into the three-dimensional boron nitride foam obtained in step (2). The impregnation was carried out at room temperature for 15 h and then dried at 65 °C for 24 h to obtain the final product. The yield of the composite product was 48-52%.

[0018] Example 3: (1) Dissolve 1.5g of melamine in 100ml of dichloromethane, then gradually add an aqueous solution of oxalic acid catalyst to the dichloromethane, followed by the sequential addition of a dichloromethane solution of terephthalaldehyde. The mixture is then placed in a high-pressure tube and heated to 115°C. o C reaction, reaction time 48h, product collected by ultrasound, and washed with acetone solvent; (2) Three-dimensional boron nitride foam was produced by gas foaming. A mixture of 200 mg ammonia borane and 70 mg thiourea in an alumina crucible was heated to 700 °C at a heating rate of 7 °C per minute. The entire reaction was protected by a gas flow of N2. The reaction was maintained at 700 °C for 4 hours until it was complete. After cooling to room temperature, the three-dimensional boron nitride foam was collected. (3) The product obtained in step (1) was impregnated with polystyrene binder at a mass ratio of 12 wt% into the three-dimensional boron nitride foam obtained in step (2). The impregnation was carried out at room temperature for 18 h and then dried at 70 °C for 24 h to obtain the final product. The yield of the composite product was 55-60%.

[0019] Example 4: (1) Dissolve 1.6g of p-phenylenediamine in 100ml of dichloromethane, then gradually add an aqueous solution of citric acid as a catalyst to the dichloromethane, followed by the sequential addition of a dichloromethane solution of p-phenylenedialdehyde. The solution is then placed in a high-pressure tube and heated to 120°C. o The reaction was carried out at C for 100 hours. The product was collected by ultrasound and washed with acetone. (2) Three-dimensional boron nitride foam was produced by gas foaming. A mixture of 300 mg ammonia borane and 80 mg thiourea in an alumina crucible was heated to 750 °C at a heating rate of 8 °C per minute. The entire reaction was protected by a gas flow of N2. The reaction was maintained at 750 °C for 6 hours until it was complete. After cooling to room temperature, the three-dimensional boron nitride foam was collected. (3) The product obtained in step (1) was impregnated with polystyrene binder at a mass ratio of 15 wt% into the three-dimensional boron nitride foam obtained in step (2). The impregnation was carried out at room temperature for 10 h and then dried at 75 °C for 24 h to obtain the final product. The yield of the composite product was 62-70%.

[0020] Example 5: (1) Dissolve 2g of p-phenylenediamine in 100ml of dichloromethane, then gradually add an aqueous solution of the catalyst methylbenzenesulfonic acid to the dichloromethane, followed by the sequential addition of a dichloromethane solution of 1,3,5-triformylm-phenylene. The solution is then placed in a high-pressure tube and heated to 130°C. o C reaction, reaction time 240h, product collected by ultrasound and washed with acetone solvent; (2) Three-dimensional boron nitride foam was produced by gas foaming. A mixture of 400 mg ammonia borane and 100 mg thiourea in an alumina crucible was heated to 800 °C at a heating rate of 10 °C per minute. The entire reaction was protected by a gas flow of N2. The reaction was maintained at 800 °C for 8 hours until it was complete. After cooling to room temperature, the three-dimensional boron nitride foam was collected. (3) The product obtained in step (1) was impregnated with 20 wt% polystyrene binder into the three-dimensional boron nitride foam obtained in step (2). The impregnation was carried out at room temperature for 24 h and then dried at 80 °C for 24 h to obtain the final product. The yield of the composite product was 70-76%.

[0021] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above-disclosed technical content should be considered as equivalent and valid embodiments, and all fall within the scope of protection of the present invention.

Claims

1. A three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material, characterized in that... A covalent organic framework with a periodically repeating structure was obtained through a polycondensation reaction using amine monomer A and aldehyde monomer B as raw materials. This framework was then in situ supported in a three-dimensional boron nitride foam at a loading ratio of 5 wt% to 20 wt%. The surface area of ​​the covalent organic framework was 700–1000 m². 2 / g, with a pore size of 0.5~1nm; the surface area of ​​the three-dimensional boron nitride foam is 800~1000m². 2 / g, with a pore size of 2~10um; the amine monomer A is melamine or p-phenylenediamine, and the aldehyde monomer B is terephthalaldehyde or 1,3,5-triformyl-m-phenylene; a method for preparing a three-dimensional boron nitride foam-supported organic covalent framework hydrogen storage material, comprising the following sequential steps: (1) Dissolve amine monomer A in solvent D, then gradually add an aqueous solution of catalyst E to D, and sequentially add a dichloromethane solution of aldehyde monomer B. Place the mixture in a high-pressure tube and react at a high temperature of 100~130℃ for 12h~240h. Collect the product by ultrasound and wash it with acetone. Solvent D is dichloromethane or hexane, and catalyst E is trifluoromethanesulfonic acid, acetic acid, oxalic acid, citric acid or methylbenzenesulfonic acid. (2) Three-dimensional boron nitride foam is produced by gas foaming. A mixture of 100-400 mg ammonia borane and 50-100 mg thiourea in an alumina crucible is heated to 600-800 °C at a heating rate of 5-10 °C per minute. The entire reaction is protected by N2 gas flow. The reaction is maintained at 600-800 °C for 2-8 hours until the reaction is complete. After cooling to room temperature, the three-dimensional boron nitride foam is collected. (3) The product obtained in step (1) is impregnated with polystyrene binder in a mass ratio into the three-dimensional boron nitride foam obtained in step (2), impregnated at room temperature for 12-24 hours and then dried at 60-80℃ to obtain the final product.

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