A magnesium-based hydrogen storage material and preparation method thereof

Abstract

The present invention belongs to the technical field of hydrogen storage materials, and specifically relates to a magnesium-based hydrogen storage material and a preparation method thereof. The preparation method comprises the following steps: S1: ball-milling Mg and 2,7-pyrenediamine, and calcining to obtain Mg-C; S2: subjecting the Mg-C to a hydrogenation combustion treatment and ball-milling to obtain MgH2-C; and S3: ball-milling the MgH2-C, a carbon aerogel, and an additive to obtain the magnesium-based hydrogen storage material. The present invention improves the hydrogen absorption and desorption rate of the magnesium-based hydrogen storage material by optimizing the magnesium-based hydrogen storage material system and preparation method. The magnesium-based hydrogen storage material prepared using this method has excellent hydrogen absorption and desorption performance and cyclic stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage materials, and in particular relates to a magnesium-based hydrogen storage material and a preparation method thereof. Background Art

[0002] Hydrogen is a highly energy-dense and truly clean energy source. Its storage and transportation are crucial in its utilization. Hydrogen can be stored and transported in three primary forms: high-pressure gas, liquid, and solid. Compared to high-pressure gas and liquid forms, solid-state hydrogen storage offers advantages such as lower energy consumption and higher volumetric hydrogen storage density. Therefore, solid-state hydrogen storage materials are a key factor in determining solid-state hydrogen storage technology.

[0003] Solid-state hydrogen storage using metal hydrides is one of the feasible hydrogen storage methods. Among them, the most popular hydrogen storage metal material is magnesium-based hydrogen storage material. Magnesium is a hydrogen storage material with relatively close ideal characteristics: (1) my country is rich in magnesium resources; (2) after absorbing hydrogen, it turns into magnesium hydride. Magnesium hydride can be converted into magnesium and release hydrogen under certain temperature and pressure conditions with good reversibility; (3) it has light weight and low density. Therefore, magnesium is considered to be one of the most promising hydrogen storage materials.

[0004] A Chinese patent application, publication number CN102212721A, discloses a magnesium-nickel-based hydrogen storage material and preparation method. The material, consisting of 2MgNi-xB (x = 1%-15%), is synthesized by mechanical ball milling by mixing magnesium and nickel in an atomic ratio of 2:1, then adding varying amounts of boron according to the aforementioned mass percentages. While the addition of boron to this magnesium-nickel-based hydrogen storage material improves its hydrogen absorption rate compared to Mg2Ni, the hydrogen absorption kinetics curves show that other boron-containing samples take a relatively long time to reach maximum hydrogen absorption, reaching 90% of their maximum absorption capacity between 600 and 900 seconds. This limits its practical application in applications requiring rapid hydrogen charging and discharging. Summary of the Invention

[0005] Existing magnesium-based hydrogen storage materials have the problem of low hydrogen absorption and desorption rates. In order to solve this problem, the present invention provides a magnesium-based hydrogen storage material and a preparation method thereof.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a magnesium-based hydrogen storage material, comprising the following steps:

[0008] S1: ball milling Mg and 2,7-pyrenediamine, and calcining to obtain Mg-C;

[0009] S2: Mg-C is subjected to hydrogenation combustion treatment and ball milling to obtain MgH2-C;

[0010] S3: ball milling MgH2-C, carbon aerogel and additives to obtain magnesium-based hydrogen storage materials.

[0011] By adopting the above technical scheme, Mg and 2,7-pyrenediamine are ball-milled and calcined to obtain Mg-C. The introduction of carbon material can increase the specific surface area of ​​the material, increase the active sites of the reaction, help improve the hydrogen absorption and desorption kinetics of magnesium, and improve the hydrogen storage capacity; hydrogenation combustion treatment can fully hydrogenate Mg to produce MgH2, further improving the hydrogen storage capacity of the material. In this process, the presence of carbon can disperse and stabilize MgH2 particles, preventing MgH2 from agglomerating during the hydrogen absorption and desorption process, thereby maintaining the good hydrogen absorption and desorption performance of the material; finally, MgH2-C is ball-milled with carbon aerogel and additives to obtain a magnesium-based hydrogen storage material. The carbon aerogel has a high specific surface area and pore structure, providing a channel for hydrogen diffusion and improving the cyclic stability of the material; the addition of additives can reduce the hydrogen absorption and desorption temperature of MgH2 and improve the hydrogen absorption and desorption performance of the MgH2 hydrogen storage material.

[0012] Preferably, in step S1, the molar ratio of Mg to 2,7-pyrenediamine is 1:(0.11-0.17).

[0013] By adopting the above technical solution, at this ratio, 2,7-pyrene diamine can be evenly dispersed in the Mg matrix, and during the calcination process, a uniform and stable Mg-C structure is formed, which helps to increase the specific surface area of ​​the material and form more active sites.

[0014] Preferably, in step S3, the mass ratio of MgH2-C, carbon aerogel and additive is (85-88): (5-8): (4-10).

[0015] By adopting the above technical solution, too little carbon aerogel can easily lead to poor dispersion of MgH2-C in the material, making it easy to agglomerate, while reducing the specific surface area and porosity of the material, thereby reducing the adsorption and diffusion channels of hydrogen; if the additive is used in too little amount, the hydrogen absorption and desorption temperature cannot be effectively reduced, affecting the hydrogen storage performance of the material.

[0016] Preferably, in step S3, the method for preparing carbon aerogel comprises the following steps:

[0017] (1) Resorcinol, furfural, pyrazole, emulsifier and acetone are uniformly mixed, aged, dried and carbonized to obtain an intermediate product;

[0018] (2) The intermediate product is mixed evenly with a hexadecyltrimethylammonium bromide solution, dried, and heat-treated to obtain a carbon aerogel.

[0019] By adopting the above technical solution, the prepared carbon aerogel has a high specific surface area and a good pore structure.

[0020] Preferably, in step (1), the ratio of resorcinol to furfural is 1 g: (1.5-2) mL; the amount of pyrazole is 6%-8% of the mass of resorcinol; and the amount of emulsifier is 0.5%-1% of the mass of resorcinol.

[0021] By adopting the above technical solution, furfural can fully react with resorcinol at this dosage, which helps to form a rich pore structure in the carbon aerogel. The use of pyrazole can avoid the introduction of excessive impurities while well regulating the pore structure of the carbon aerogel. The amount of emulsifier is controlled within the range of 0.5%-1%, which can evenly disperse resorcinol and furfural and other substances, thereby improving the uniformity of the reaction.

[0022] Preferably, in step (2), the mass fraction of the cetyltrimethylammonium bromide solution is 10%, and the usage ratio of the intermediate product to the cetyltrimethylammonium bromide solution is 1 g: (15-20) mL.

[0023] By adopting the above technical solution, the intermediate product is immersed in a hexadecyltrimethylammonium bromide solution, which can increase the specific surface area of ​​the carbon aerogel and optimize the pore structure of the carbon aerogel.

[0024] Preferably, in step (2), the heat treatment process is as follows: in a carbon dioxide atmosphere, heating to 500-800°C at a heating rate of 5°C / min and keeping the temperature for 3-4 hours.

[0025] By adopting the above technical solution, heat treatment under a carbon dioxide atmosphere can further increase the pore size of the carbon aerogel and improve the specific surface area of ​​the carbon aerogel.

[0026] Preferably, in step S1, the additive is Ni3(VO4)2, and the preparation method of Ni3(VO4)2 comprises the following steps:

[0027] Nickel nitrate hexahydrate, ammonium vanadate, ethylenediaminetetraacetic acid and water are uniformly mixed, the pH is adjusted to 9-10, hydrothermal reaction is carried out, centrifugation is carried out, washing is carried out, drying is carried out, and calcination is carried out to obtain Ni3(VO4)2.

[0028] By adopting the above technical solution and using Ni3(VO4)2 as an additive, Ni3(VO4)2 can be evenly distributed on the MgH2-C matrix, which can improve the hydrogen absorption and desorption kinetics of MgH2-C and improve the cyclic hydrogen absorption and desorption performance of MgH2-C.

[0029] Preferably, the molar ratio of nickel nitrate hexahydrate to ammonium vanadate is (1.3-1.6):1; the reaction temperature is 200-220°C, and the reaction time is 10-12 hours; the calcination process is as follows: heating to 480-550°C at a heating rate of 5°C / min and calcining for 4-5 hours.

[0030] By adopting the above technical solution, under the reaction conditions, nickel nitrate hexahydrate and ammonium vanadate can be fully contacted and reacted, which is conducive to the formation of Ni3(VO4)2 with good crystallization and uniform particles.

[0031] Preferably, in step S1, step S2 and step S3, the ball milling process is as follows: the diameters of the steel balls used in ball milling are 6 mm and 10 mm, the ball-to-material mass ratio is 35:1, the mass ratio of large balls to small balls is 1:1.5, and each ball milling is 20 minutes, with a 10-minute interruption.

[0032] In a second aspect, the present invention provides a magnesium-based hydrogen storage material prepared according to the above-mentioned method for preparing magnesium-based hydrogen storage material.

[0033] In summary, the beneficial effects of the present invention are:

[0034] (1) The present invention calcines Mg and 2,7-pyrene diamine to obtain Mg-C, and introduces carbon material into the Mg matrix, which can effectively reduce the hydrogen absorption and desorption temperature of the magnesium-based hydrogen storage material and improve the hydrogen absorption and desorption reaction kinetics of the magnesium-based hydrogen storage material; at the same time, the carbon material can also inhibit the occurrence of agglomeration and improve the hydrogen storage performance of the magnesium-based hydrogen storage material;

[0035] (2) The present invention prepares a carbon aerogel with a high specific surface area and a good pore structure. Through the impregnation of hexadecyltrimethylammonium bromide solution and the activation of carbon dioxide, the stability of the three-dimensional network structure of the carbon aerogel is enhanced, and the pore size of the three-dimensional network structure of the carbon aerogel is further expanded. The expanded pore size is conducive to the adsorption and diffusion of hydrogen;

[0036] (3) The present invention prepares Ni3(VO4)2 and adds it as an additive to magnesium-based hydrogen storage materials, which can play a catalytic role, reduce the hydrogen absorption and desorption temperature of magnesium-based materials, accelerate the hydrogen absorption and desorption rate, and improve the kinetic properties of the materials;

[0037] (4) The present invention improves the hydrogen absorption and desorption rate of magnesium-based hydrogen storage materials by optimizing the magnesium-based hydrogen storage material system and preparation method. The magnesium-based hydrogen storage material prepared by this method has excellent hydrogen absorption and desorption performance and cyclic stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the SEM morphology of the magnesium-based hydrogen storage material prepared in Example 1;

[0039] Figure 2 1 is a pore size distribution diagram of the carbon aerogels prepared in Example 1 and Comparative Example 1;

[0040] Figure 3 The DSC curves of the magnesium-based hydrogen storage materials prepared in Example 1 and Comparative Example 6 at a heating rate of 10°C / min are shown. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is explained in detail below with reference to several representative embodiments of the present invention.

[0042] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples and comparative examples are all commercially available.

[0043] The processes of reagent weighing, storage, transfer, and sample loading and unloading in the following examples and comparative examples were all performed in a glove box filled with high-purity argon to avoid oxidation.

[0044] The ball milling process in the following examples and comparative examples is as follows: the diameters of the steel balls are 6 mm and 10 mm, the ball-to-material mass ratio is 35:1, the mass ratio of large balls to small balls is 1:1.5, and each ball milling is 20 minutes, followed by a 10-minute break.

[0045] Example 1

[0046] A magnesium-based hydrogen storage material of this embodiment is prepared by the following method for preparing magnesium-based hydrogen storage materials.

[0047] A method for preparing a magnesium-based hydrogen storage material in this embodiment comprises the following specific steps:

[0048] S1: Add 2.43 g of Mg and 3.25 g of 2,7-pyrenediamine into a ball mill and mill at 300 r / min for 1.5 h. Then seal the mill and transfer it to a tube furnace. Under an argon atmosphere, heat the temperature to 1050 °C at a heating rate of 5 °C / min and hold for 3 h. Then cool the mixture naturally to room temperature to obtain Mg-C.

[0049] S2: Transfer 5 g of Mg-C into the sample tube of the PCT instrument and heat it at 5 °C / min under a hydrogen pressure of 4 MPa. -1 The temperature was raised to 400°C at a heating rate of 1000 rpm and kept at this temperature for 24 h. The mixture was naturally cooled to room temperature and transferred to a ball mill and milled at a speed of 800 rpm for 6 h to obtain MgH2-C.

[0050] S3: 8.5 g MgH2-C, 0.6 g carbon aerogel and 0.9 g additive were added to a ball mill and milled at a speed of 600 r / min for 15 h to obtain a magnesium-based hydrogen storage material; the SEM morphology of the magnesium-based hydrogen storage material is shown in Figure 1 ,Depend on Figure 1 It can be seen that the internal particles of the magnesium-based hydrogen storage material are basically around 1 μm, evenly distributed, and there is no obvious agglomeration phenomenon.

[0051] The preparation method of the carbon aerogel of this embodiment comprises the following specific steps:

[0052] (1) 11.01 g of resorcinol, 18.7 mL of furfural, 0.77 g of pyrazole and 80 mL of acetone were added to a three-necked flask and stirred at 40 °C for 20 min. 0.077 g of emulsifier was added and stirred for 10 min. The mixture was transferred to a constant temperature water bath at 80 °C and aged for 72 h. The aged material was taken out and dried in a vacuum drying oven at 80 °C for 10 h. The material was transferred to a high-temperature carbonization furnace and carbonized at 950 °C for 5 h to obtain an intermediate product.

[0053] (2) 10 g of the intermediate product and 15 mL of a 10% hexadecyltrimethylammonium bromide solution were added to a beaker, stirred at 50 °C for 12 h, dried in a vacuum drying oven at 60 °C for 12 h, and heated to 750 °C at a heating rate of 5 °C / min in a carbon dioxide atmosphere and kept at this temperature for 4 h to obtain carbon aerogel.

[0054] The carbon aerogel prepared in Example 1 was subjected to nitrogen isothermal adsorption and desorption tests. The results showed that the specific surface area of ​​the carbon aerogel prepared in this example was 1952 m 2 / g.

[0055] The preparation method of Ni3(VO4)2 in this embodiment has the following specific steps:

[0056] Add 43.62 g of nickel nitrate hexahydrate, 11.7 g of ammonium vanadate, 2.92 g of ethylenediaminetetraacetic acid and 100 mL of water into a three-necked flask and stir for 1 hour. Adjust the pH to 9, transfer the mixture to an autoclave, heat it to 220 ° C for hydrothermal reaction for 12 hours, cool it to room temperature, centrifuge it, wash it with anhydrous ethanol 3 times, wash it with water 3 times, dry it at 80 ° C in a vacuum drying oven for 12 hours, transfer it to a tubular furnace, heat it to 500 ° C at a heating rate of 5 ° C / min and calcine it for 5 hours to obtain Ni3(VO4)2.

[0057] Example 2

[0058] A magnesium-based hydrogen storage material of this embodiment is prepared by the following method for preparing magnesium-based hydrogen storage materials.

[0059] A method for preparing a magnesium-based hydrogen storage material in this embodiment comprises the following specific steps:

[0060] S1: Add 2.43 g of Mg and 2.56 g of 2,7-pyrenediamine into a ball mill and mill at 300 r / min for 1.5 h. Then seal the mill and transfer it to a tube furnace. Under an argon atmosphere, heat the furnace to 1050 °C at a heating rate of 5 °C / min, hold the temperature for 3 h, and cool it naturally to room temperature to obtain Mg-C.

[0061] S2: Transfer 5 g of Mg-C into the sample tube of the PCT instrument and heat it at 5 °C / min under a hydrogen pressure of 4 MPa. -1 The temperature was raised to 400°C at a heating rate of 1000 rpm and kept at this temperature for 24 h. The mixture was naturally cooled to room temperature and transferred to a ball mill and milled at a speed of 800 rpm for 6 h to obtain MgH2-C.

[0062] S3: 8.8 g of MgH2-C, 0.7 g of carbon aerogel and 0.5 g of additives were added to a ball mill and ball milled at a speed of 600 r / min for 15 h to obtain a magnesium-based hydrogen storage material.

[0063] The preparation method of the carbon aerogel of this embodiment comprises the following specific steps:

[0064] (1) 11.01 g of resorcinol, 16.6 mL of furfural, 0.88 g of pyrazole and 80 mL of acetone were added to a three-necked flask and stirred at 40 °C for 20 min. 0.056 g of emulsifier was added and stirred for 10 min. The mixture was transferred to a constant temperature water bath at 80 °C and aged for 72 h. The aged material was taken out and dried in a vacuum drying oven at 80 °C for 10 h. The material was transferred to a high-temperature carbonization furnace and carbonized at 950 °C for 5 h to obtain an intermediate product.

[0065] (2) 10 g of the intermediate product and 16 mL of a 10% hexadecyltrimethylammonium bromide solution were added to a beaker, stirred at 50 °C for 12 h, dried in a vacuum drying oven at 60 °C for 12 h, and heated to 500 °C at a heating rate of 5 °C / min in a carbon dioxide atmosphere and kept at this temperature for 4 h to obtain carbon aerogel.

[0066] The carbon aerogel prepared in Example 2 was subjected to nitrogen isothermal adsorption and desorption tests. The results showed that the specific surface area of ​​the carbon aerogel prepared in this example was 1845 m 2 / g.

[0067] The preparation method of Ni3(VO4)2 in this embodiment has the following specific steps:

[0068] Add 37.9 g of nickel nitrate hexahydrate, 11.7 g of ammonium vanadate, 2.92 g of ethylenediaminetetraacetic acid and 100 mL of water into a three-necked flask and stir for 1 hour. Adjust the pH to 9, transfer the mixture to an autoclave, heat it to 200 ° C for hydrothermal reaction for 12 hours, cool it to room temperature, centrifuge it, wash it with anhydrous ethanol 3 times, wash it with water 3 times, dry it at 80 ° C in a vacuum drying oven for 12 hours, transfer it to a tubular furnace, heat it to 550 ° C at a heating rate of 5 ° C / min and calcine it for 4 hours to obtain Ni3(VO4)2.

[0069] Example 3

[0070] A magnesium-based hydrogen storage material of this embodiment is prepared by the following method for preparing magnesium-based hydrogen storage materials.

[0071] A method for preparing a magnesium-based hydrogen storage material in this embodiment comprises the following specific steps:

[0072] S1: Add 2.43 g of Mg and 3.93 g of 2,7-pyrenediamine into a ball mill and mill at 300 r / min for 1.5 h. Then seal the mill and transfer it to a tube furnace. Under an argon atmosphere, heat the temperature to 1050 °C at a heating rate of 5 °C / min and hold for 3 h. Then cool the mixture naturally to room temperature to obtain Mg-C.

[0073] S2: 5 g of Mg-C was transferred to the sample tube of the PCT instrument and heated at 5 °C / min under a hydrogen pressure of 4 MPa. -1 The temperature was raised to 400°C at a heating rate of 1000 rpm and kept at this temperature for 24 h. The mixture was naturally cooled to room temperature and transferred to a ball mill and milled at a speed of 800 rpm for 6 h to obtain MgH2-C.

[0074] S3: 8.6 g of MgH2-C, 0.8 g of carbon aerogel and 0.6 g of additive were added to a ball mill and ball milled at a speed of 600 r / min for 15 h to obtain a magnesium-based hydrogen storage material.

[0075] The preparation method of the carbon aerogel of this embodiment comprises the following specific steps:

[0076] (1) 11.01 g of resorcinol, 22 mL of furfural, 0.67 g of pyrazole and 80 mL of acetone were added to a three-necked flask and stirred at 40 °C for 20 min. 0.11 g of emulsifier was added and stirred for 10 min. The mixture was transferred to a constant temperature water bath at 80 °C and aged for 72 h. The aged material was taken out and dried in a vacuum drying oven at 80 °C for 10 h. The material was transferred to a high-temperature carbonization furnace and carbonized at 950 °C for 5 h to obtain an intermediate product.

[0077] (2) 10 g of the intermediate product and 18 mL of a 10% hexadecyltrimethylammonium bromide solution were added to a beaker, stirred at 50 °C for 12 h, dried in a vacuum drying oven at 60 °C for 12 h, and heated to 800 °C at a heating rate of 5 °C / min in a carbon dioxide atmosphere and kept at this temperature for 3 h to obtain carbon aerogel.

[0078] The carbon aerogel prepared in Example 3 was subjected to nitrogen isothermal adsorption and desorption tests. The results showed that the specific surface area of ​​the carbon aerogel prepared in this example was 1879 m 2 / g.

[0079] The preparation method of Ni3(VO4)2 in this embodiment has the following specific steps:

[0080] Add 46.5 g of nickel nitrate hexahydrate, 11.7 g of ammonium vanadate, 2.92 g of ethylenediaminetetraacetic acid and 100 mL of water into a three-necked flask and stir for 1 h. Adjust the pH to 10, transfer the mixture to an autoclave, heat it to 210 ° C for hydrothermal reaction for 11 h, cool it to room temperature, centrifuge it, wash it with anhydrous ethanol 3 times, wash it with water 3 times, dry it in a vacuum drying oven at 80 ° C for 12 h, transfer it to a tubular furnace, heat it to 530 ° C at a heating rate of 5 ° C / min and calcine it for 4 h to obtain Ni3(VO4)2.

[0081] Example 4

[0082] A magnesium-based hydrogen storage material of this embodiment is prepared by the following method for preparing magnesium-based hydrogen storage materials.

[0083] A method for preparing a magnesium-based hydrogen storage material in this embodiment comprises the following specific steps:

[0084] S1: Add 2.43 g of Mg and 3.72 g of 2,7-pyrenediamine into a ball mill and mill at 300 r / min for 1.5 h. Then seal the mill and transfer it to a tube furnace. Under an argon atmosphere, heat the temperature to 1050 °C at a heating rate of 5 °C / min, hold the temperature for 3 h, and cool it naturally to room temperature to obtain Mg-C.

[0085] S2: 5 g of Mg-C was transferred to the sample tube of the PCT instrument and heated at 5 °C / min under a hydrogen pressure of 4 MPa. -1 The temperature was raised to 400°C at a heating rate of 1000 rpm and kept at this temperature for 24 h. The mixture was naturally cooled to room temperature and transferred to a ball mill and milled at a speed of 800 rpm for 6 h to obtain MgH2-C.

[0086] S3: 8.7 g of MgH2-C, 0.5 g of carbon aerogel and 0.8 g of additives were added to a ball mill and ball milled at a speed of 600 r / min for 15 h to obtain a magnesium-based hydrogen storage material.

[0087] The preparation method of the carbon aerogel of this embodiment comprises the following specific steps:

[0088] (1) 11.01 g of resorcinol, 16.6 mL of furfural, 0.7 g of pyrazole and 80 mL of acetone were added to a three-necked flask and stirred at 40 °C for 20 min. 0.088 g of emulsifier was added and stirred for 10 min. The mixture was transferred to a constant temperature water bath at 80 °C and aged for 72 h. The aged material was taken out and dried in a vacuum drying oven at 80 °C for 10 h. The material was transferred to a high-temperature carbonization furnace and carbonized at 950 °C for 5 h to obtain an intermediate product.

[0089] (2) 10 g of the intermediate product and 20 mL of 10% hexadecyltrimethylammonium bromide solution were added to a beaker, stirred at 50 °C for 12 h, dried in a vacuum drying oven at 60 °C for 12 h, and heated to 600 °C at a heating rate of 5 °C / min in a carbon dioxide atmosphere and kept at this temperature for 3 h to obtain carbon aerogel.

[0090] The carbon aerogel prepared in Example 4 was subjected to nitrogen isothermal adsorption and desorption tests. The results showed that the specific surface area of ​​the carbon aerogel prepared in this example was 1946 m 2 / g.

[0091] The preparation method of Ni3(VO4)2 in this embodiment has the following specific steps:

[0092] Add 40.71 g of nickel nitrate hexahydrate, 11.7 g of ammonium vanadate, 2.92 g of ethylenediaminetetraacetic acid and 100 mL of water into a three-necked flask and stir for 1 hour. Adjust the pH to 10, transfer the mixture to an autoclave, heat it to 200 ° C for hydrothermal reaction for 10 hours, cool it to room temperature, centrifuge it, wash it with anhydrous ethanol 3 times, wash it with water 3 times, dry it at 80 ° C in a vacuum drying oven for 12 hours, transfer it to a tubular furnace, heat it to 480 ° C at a heating rate of 5 ° C / min and calcine it for 5 hours to obtain Ni3(VO4)2.

[0093] Comparative Example 1

[0094] The difference from Example 1 is that in the preparation method of carbon aerogel in this comparative example, step (2) is not performed, and the rest is the same as Example 1.

[0095] The carbon aerogel prepared in Comparative Example 1 was subjected to nitrogen isothermal adsorption and desorption tests. The results showed that the specific surface area of ​​the carbon aerogel prepared in this comparative example was 474 m 2 / g, the pore size distribution of carbon aerogels prepared in Example 1 and Comparative Example 1 is shown in Figure 2 .

[0096] Comparative Example 2

[0097] The difference from Example 1 is that the preparation method of a magnesium-based hydrogen storage material in this comparative example has the following specific steps: S1: Mg is subjected to hydrogenation combustion treatment and ball milling to obtain MgH2; S2: MgH2, carbon aerogel and additives are ball milled to obtain a magnesium-based hydrogen storage material; the rest are the same as Example 1.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that no carbon aerogel is added in the preparation of step S3 in this comparative example, and the rest is the same as Example 1.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that Ni3(VO4)2 is not added in the preparation of step S3 in this comparative example, and the rest is the same as Example 1.

[0102] Comparative Example 5

[0103] The difference from Example 1 is that in the preparation of step S3, the added amounts of MgH2-C, carbon aerogel and additive in this comparative example are 7.4 g, 1.2 g and 1.4 g respectively, and the rest are the same as in Example 1.

[0104] Comparative Example 6

[0105] The difference from Example 1 is that in this comparative example, Mg is directly subjected to hydrogenation combustion treatment and ball milling to obtain MgH2.

[0106] The hydrogen release performance of the magnesium-based hydrogen storage materials prepared in Example 1 and Comparative Example 6 at a heating rate of 10°C / min was tested by DSC. The DSC curves are shown in FIG. Figure 3 .

[0107] Related performance tests

[0108] The magnesium-based hydrogen storage materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 were subjected to hydrogen absorption and desorption performance tests in a PCT tester: the test conditions were 250°C, the hydrogen absorption performance tests of the samples were all carried out under an initial hydrogen pressure of 3 MPa, and the hydrogen desorption performance tests were all carried out under an initial hydrogen pressure of 0.1 MPa. The test results are shown in Table 1.

[0109] Table 1 Test results

[0110]

[0111] Comparison of Comparative Example 1 and Comparative Example 3 with Example 1 and Figure 2It can be seen that the introduction of carbon aerogel can improve the hydrogen absorption and desorption performance of magnesium-based hydrogen storage materials; at the same time, the intermediate product is impregnated with hexadecyltrimethylammonium bromide solution and heat-treated under a carbon dioxide atmosphere. The pore size of the obtained carbon aerogel is significantly larger than that of the carbon aerogel that has not been impregnated and heat-treated, and the specific surface area is also significantly increased. The expansion of the pore size of the carbon aerogel is conducive to the diffusion and transmission of hydrogen inside the hydrogen storage material, reducing the resistance of hydrogen in the pores, further accelerating the hydrogen absorption and desorption rate of the magnesium-based hydrogen storage material, and improving the kinetic performance.

[0112] From the comparison between Comparative Example 2 and Example 1, it can be seen that co-sintering 2,7-pyrenediamine with magnesium can introduce carbon material into magnesium, which helps to increase the specific surface area of ​​the magnesium-based hydrogen storage material and form more active sites. At the same time, it can inhibit the agglomeration of particles and improve the hydrogen absorption and desorption properties of the magnesium-based hydrogen storage material.

[0113] From the comparison between Comparative Example 4 and Example 1, it can be seen that the addition of Ni3(VO4)2 can improve the hydrogen absorption and desorption performance of the magnesium-based hydrogen storage material; the addition of Ni3(VO4)2 can weaken the Mg-H bond and accelerate the hydrogen absorption and desorption rate; the elements such as Ni and V in Ni3(VO4)2 can form NiH phase and V2O3 phase, which catalyze the hydrogen absorption and desorption reaction.

[0114] By comparing Comparative Example 5 with Example 1, it can be seen that changing the added amounts of MgH2-C, carbon aerogel and additives reduces the hydrogen absorption and desorption performance of the magnesium-based hydrogen storage material, proving that the ratio of MgH2-C, carbon aerogel and additives in the present invention has reached the optimal ratio.

[0115] By comparing Comparative Example 6 with Example 1 and combining Figure 3 It can be seen that the magnesium-based hydrogen storage material prepared in Comparative Example 6 has an endothermic peak at 374°C and an initial hydrogen desorption temperature of 342°C. The magnesium-based hydrogen storage material prepared in Example 1 has a peak hydrogen desorption temperature reduced to 287°C and an initial hydrogen desorption temperature reduced to 246°C. This shows that the introduction of carbon materials, carbon aerogels, and additives can accelerate the diffusion rate of hydrogen atoms in the material, significantly improving the hydrogen absorption and desorption properties.

[0116] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium-based hydrogen storage material, characterized in that: The steps include: S1: ball milling Mg and 2,7-pyrenediamine, and calcining to obtain Mg-C; S2: Mg-C is subjected to hydrogenation combustion treatment and ball milling to obtain MgH2-C; S3: ball milling MgH2-C, carbon aerogel and additives to obtain magnesium-based hydrogen storage materials.

2. The method for preparing a magnesium-based hydrogen storage material according to claim 1, characterized in that: In the step S1, the molar ratio of Mg to 2,7-pyrenediamine is 1:(0.11-0.17).

3. The method for preparing a magnesium-based hydrogen storage material according to claim 1, characterized in that: In step S3, the mass ratio of MgH2-C, carbon aerogel and additive is (85-88): (5-8): (4-10).

4. The method for preparing a magnesium-based hydrogen storage material according to claim 1, characterized in that: In step S3, the method for preparing carbon aerogel comprises the following steps: (1) Resorcinol, furfural, pyrazole, emulsifier and acetone are uniformly mixed, aged, dried and carbonized to obtain an intermediate product; (2) The intermediate product is mixed evenly with a hexadecyltrimethylammonium bromide solution, dried, and heat-treated to obtain a carbon aerogel.

5. The method for preparing a magnesium-based hydrogen storage material according to claim 4, characterized in that: In the step (1), the ratio of resorcinol to furfural is 1 g: (1.5-2) mL; the amount of pyrazole is 6%-8% of the mass of resorcinol; and the amount of emulsifier is 0.5%-1% of the mass of resorcinol.

6. The method for preparing a magnesium-based hydrogen storage material according to claim 4, characterized in that: In the step (2), the mass fraction of the cetyltrimethylammonium bromide solution is 10%, and the usage ratio of the intermediate product to the cetyltrimethylammonium bromide solution is 1 g: (15-20) mL.

7. The method for preparing a magnesium-based hydrogen storage material according to claim 4, characterized in that: In step (2), the heat treatment process is as follows: in a carbon dioxide atmosphere, the temperature is raised to 500-800°C at a heating rate of 5°C / min and kept at this temperature for 3-4 hours.

8. The method for preparing a magnesium-based hydrogen storage material according to claim 1, characterized in that: In step S1, the additive is Ni3(VO4)2, and the preparation method of Ni3(VO4)2 includes the following steps: Nickel nitrate hexahydrate, ammonium vanadate, ethylenediaminetetraacetic acid and water are uniformly mixed, the pH is adjusted to 9-10, hydrothermal reaction is carried out, centrifugation is carried out, washing is carried out, drying is carried out, and calcination is carried out to obtain Ni3(VO4)2.

9. The method for preparing a magnesium-based hydrogen storage material according to claim 8, characterized in that: The molar ratio of nickel nitrate hexahydrate to ammonium vanadate is (1.3-1.6):1; the reaction temperature is 200-220°C, and the reaction time is 10-12 hours; the calcination process is as follows: heating to 480-550°C at a heating rate of 5°C / min and calcining for 4-5 hours.

10. A magnesium-based hydrogen storage material prepared by the method for preparing a magnesium-based hydrogen storage material according to any one of claims 1 to 9.

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