A FeVO4-MgH2 composite hydrogen storage material, its preparation method and its application

Abstract

The application relates to the field of hydrogen storage materials, in particular to a FeVO4-MgH2 composite hydrogen storage material, a preparation method and application thereof, the FeVO4-MgH2 composite hydrogen storage material comprises MgH2 and a FeVO4 catalyst, wherein the total mass of the FeVO4-MgH2 composite hydrogen storage material is 100%, and the mass fraction of the FeVO4 is 2%-6%. The preparation method comprises the following steps: preparing 94%-98% of MgH2 and 2%-6% of the FeVO4 catalyst, and mixing and ball milling the two to obtain the FeVO4-MgH2 composite hydrogen storage material. Through implementation of the scheme, the hydrogen storage material capable of reducing thermodynamic stability and improving hydrogen absorption and release dynamic performance is obtained.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage materials, specifically to a FeVO4-MgH2 composite hydrogen storage material, its preparation method, and its application. Background Technology

[0002] Against the backdrop of dwindling global energy resources, new energy sources have become a research hotspot, with hydrogen energy gaining increasing acceptance due to its high energy density, renewability, and cleanliness. Hydrogen storage is a crucial component in hydrogen utilization. Magnesium-based hydrogen storage materials, with their advantages of high hydrogen storage density, abundant resources, and low cost, are considered among the most promising solid-state hydrogen storage materials. MgH2, with its high hydrogen storage capacity (7.6 wt%), abundant reserves (China is one of the world's richest countries in magnesium resources, accounting for 22.5% of global reserves), low cost, and high safety, is increasingly being used in laboratories and is considered one of the most promising solid-state hydrogen storage materials for development.

[0003] Currently, magnesium-based hydrogen storage in my country is still in the laboratory research stage and cannot be used on a large scale. This is because, on the one hand, MgH2 has high thermodynamic stability (its dehydrogenation temperature is usually 300-400℃, far exceeding the requirements of practical applications), and on the other hand, its reaction kinetics are slow (the reaction rate of MgH2 is low during hydrogen storage and dehydrogenation, limiting its energy release efficiency). To solve these problems and improve the hydrogen absorption / desorption performance of MgH2, the current focus is on developing highly efficient catalysts. For example, CN 119680567B discloses a method for preparing rare earth high-entropy alloy catalysts and their applications. Although this method improves the hydrogen absorption / desorption capacity, the problems of high thermodynamic stability and slow reaction kinetics have not been effectively solved. Therefore, it is necessary to design a hydrogen storage material that can reduce thermodynamic stability and improve hydrogen absorption / desorption kinetics. Summary of the Invention

[0004] One of the objectives of this invention is to provide a FeVO4-MgH2 composite hydrogen storage material. Through the synergistic combination and precise ratio configuration of FeVO4 and MgH2, not only is the hydrogen storage capacity of the material increased, but the hydrogen absorption and desorption temperature is also significantly reduced, and the hydrogen absorption and desorption reaction rate is also significantly improved.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a FeVO4-MgH2 composite hydrogen storage material, comprising MgH2 and FeVO4 catalyst, wherein the total mass of the FeVO4-MgH2 composite hydrogen storage material is 100%, and the mass fraction of FeVO4 is 2%-6%.

[0006] Preferably, as an improvement, the mass fraction of FeVO4 is 3%.

[0007] The second objective of this invention is to provide a method for preparing FeVO4-MgH2 composite hydrogen storage materials, so as to prepare FeVO4 with high purity and complete nanorod structure, and to effectively improve the hydrogen absorption and desorption performance of hydrogen storage materials by rationally preparing sheet-like FeVO4 and MgH2 composite materials.

[0008] A method for preparing a FeVO4-MgH2 composite hydrogen storage material includes the following steps: preparing MgH2 with a mass fraction of 94%-98% and FeVO4 catalyst with a mass fraction of 2%-6%, and mixing and ball milling the two to obtain the FeVO4-MgH2 composite hydrogen storage material.

[0009] Preferably, as an improvement, ball milling is performed at 350-420 r / min, with a 10-minute pause after every 10 minutes of ball milling, and the cycle is repeated 70-75 times.

[0010] Preferably, as an improvement, the preparation method of the FeVO4 catalyst includes the following steps: S01, Prepare FeCl3·6H2O and NH4VO3; SO2. Dissolve FeCl3·6H2O in deionized water and stir for 30-35 minutes to obtain solution A; SO3. Dissolve NH4VO3 in deionized water at 80℃ and stir to dissolve in a water bath at 80℃ to obtain solution B; S04. While stirring, slowly add solution B dropwise to solution A, and continue stirring for 30-40 minutes to obtain solution C; S05. After reacting solution C at 180-190℃ for 3-3.5h, cool to room temperature, centrifuge to collect the precipitate, wash the precipitate repeatedly, and dry it at 60-70℃ to obtain powder. S06. The powder obtained in S05 is calcined at 500-550℃ for 1.8-2.2h at a heating rate not exceeding 5℃ / min to obtain a rod-shaped FeVO4 catalyst.

[0011] Preferably, as an improvement, the molar ratio of FeCl3·6H2O and NH4VO3 is 1:1.

[0012] Preferably, as an improvement, in S05, solution C is placed in a stainless steel reactor lined with polytetrafluoroethylene for reaction.

[0013] Preferably, as an improvement, the atmosphere during ball milling is an inert atmosphere.

[0014] The third objective of this invention is to provide a FeVO4-MgH2 composite hydrogen storage material for application in the field of hydrogen storage materials.

[0015] The principles and advantages of this scheme are: 1. It has excellent hydrogen absorption performance: 1) Hydrogen absorption temperature reduced by 37.5%: Compared with existing hydrogen storage materials that use rare earth high-entropy alloys as catalysts, which can only achieve a hydrogen absorption of 6.13wt% at 320℃, this solution can achieve the same hydrogen absorption at only 200℃, significantly reducing the required hydrogen absorption temperature by as much as 37.5%.

[0016] 2) The hydrogen absorption rate is increased by up to 20 times: Under the condition of 200℃, the same hydrogen absorption of 6.13wt% is achieved. Using rare earth high entropy alloy as the catalyst for hydrogen storage material, it takes 120 minutes, while this solution only takes 6 minutes, which significantly increases the hydrogen absorption rate by up to 20 times.

[0017] 2. It has excellent hydrogen desorption performance: 1) The hydrogen release temperature is reduced by 26.4%: Compared with existing hydrogen storage materials that use rare earth high-entropy alloys as catalysts, which can only achieve a hydrogen release of 6.1 wt% at 340℃, this solution can achieve a higher hydrogen release of 6.31 wt% at only 250℃, which significantly reduces the hydrogen release temperature by as much as 26.4%.

[0018] 2) Hydrogen release increased by 17.6%: At 300℃, the maximum hydrogen release of this scheme can reach about 7wt%, while the hydrogen storage material using rare earth high entropy alloy as catalyst can only reach 5.95 wt%, thus increasing the hydrogen release by 17.6%.

[0019] 3) The hydrogen release rate is increased by at least 4 times: This scheme can achieve a hydrogen release rate of 7wt% in just 6 minutes at 300℃, while the hydrogen storage material using rare earth high-entropy alloy as catalyst requires 25 minutes and 340℃ to reach 6.1wt%. Therefore, this scheme increases the hydrogen release rate by at least 4 times at a relatively low temperature.

[0020] 3. Good cycle stability: After several hydrogen absorption and desorption cycles at 300℃, this hydrogen storage material shows almost no hydrogen capacity decay. The maximum hydrogen absorption capacity of the material is maintained at about 6 wt%, and the maximum hydrogen desorption capacity is maintained at 7 wt%. This indicates that the material maintains stable hydrogen storage performance under high temperature conditions and does not experience serious capacity decay. Its cycle stability is very good.

[0021] 4. Good reversibility of reaction: During each hydrogen absorption / desorption cycle, the hydrogen absorption / desorption curves are nearly symmetrical, without any obvious plateau drift or asymmetric hydrogen absorption / desorption, indicating that the hydrogen storage material has good reversibility of reaction.

[0022] 5. The FeVO4 catalyst prepared by this method has high purity, with no impurity phases generated. Furthermore, the FeVO4 catalyst has a nanorod structure, which, compared to other structures, has a relatively large specific surface area. This can further increase the contact area between the FeVO4 catalyst and MgH2, thereby improving the hydrogen storage capacity of the hydrogen storage material. Attached Figure Description

[0023] Figure 1 The XRD diffraction pattern of FeVO4 in this invention is shown.

[0024] Figure 2 This is a SEM scan of FeVO4 from the present invention.

[0025] Figure 3 This is the XPS spectrum of FeVO4 according to the present invention.

[0026] Figure 4 Isothermal hydrogen absorption curves of hydrogen storage materials with different FeVO4 doping ratios (0%, 3%, 6%, 9%) at different temperatures.

[0027] Figure 5 Isothermal hydrogen desorption curves of hydrogen storage materials with different FeVO4 doping ratios (0%, 3%, 6%, 9%) at different temperatures.

[0028] Figure 6 Cyclic performance test results for hydrogen storage materials doped with 3% FeVO4.

[0029] Figure 7 (a) is the fitting curve of the JMAK equation; Figure 7 (b) Fitting curve of the Arrhenius equation.

[0030] Figure 8 XRD patterns of ball milling, dehydrogenation, and re-hydrogen absorption of FeVO4-MgH2 composite hydrogen storage material. Detailed Implementation

[0031] The following detailed description illustrates the specific implementation method: Example 1 A FeVO4-MgH2 composite hydrogen storage material includes MgH2 and FeVO4 catalyst, wherein the total mass of the FeVO4-MgH2 composite hydrogen storage material is 100%, and the mass fraction of FeVO4 is 2%-6%. The mass fraction of FeVO4 is 2%, 3%, 4%, 5%, or 6%, with 3% being preferred in this embodiment.

[0032] The preparation method of FeVO4-MgH2 composite hydrogen storage material includes the following steps: Step 1: Preparation of FeVO4 catalyst; S01, Prepare FeCl3·6H2O and NH4VO3; SO2. Dissolve FeCl3·6H2O in deionized water and stir for 30-35 minutes to obtain solution A; SO3. Dissolve NH4VO3 in deionized water at 80℃ and stir to dissolve in a water bath at 80℃ to obtain solution B; S04. While stirring, slowly add solution B dropwise to solution A, and continue stirring for 30-40 minutes to obtain solution C; S05. After reacting solution C at 180℃ for 3 hours, cool it to room temperature, centrifuge to collect the precipitate, wash the precipitate repeatedly, and dry it at 60-70℃ to obtain powder. S06. The powder obtained in S05 is calcined at 500-550℃ for 1.8-2.2h at a heating rate not exceeding 5℃ / min to obtain a rod-shaped FeVO4 catalyst. Firstly, if the heating rate exceeds 5℃ / min, the powder is heated unevenly, resulting in inconsistent particle size and unstable morphology of the prepared FeVO4 catalyst. Secondly, a calcination time shorter than the specified time leads to uneven crystal structure, while an excessively long calcination time may cause deactivation of the FeVO4 catalyst. Finally, controlling the calcination temperature between 500-550℃ ensures optimal FeVO4 purity and catalytic performance. Excessively high calcination temperatures can cause catalyst sintering and aggregation, leading to decreased catalytic performance, while excessively low calcination temperatures result in incomplete reaction and low FeVO4 purity.

[0033] Therefore, in this embodiment, the powder is calcined at 500°C for 2 hours with a heating rate of 5°C / min.

[0034] Step 2: Preparation of FeVO4-MgH2 composite hydrogen storage material 97% by mass of MgH2 and 3% by mass of FeVO4 catalyst were ball-milled at 350-420 r / min, with a 10-min pause every 10 min of ball milling, and the cycle was repeated 70-75 times to obtain FeVO4-MgH2 composite hydrogen storage material.

[0035] Example 2: Unlike Example 1, the FeVO4 doping amount is 6%; Comparative Example 1: Unlike Example 1, the FeVO4 doping amount was 0%; Comparative Example 2: Unlike Example 1, the FeVO4 doping amount is 9%.

[0036] experiment I. FeVO4 catalyst from Figures 1-3 The images show the XRD diffraction pattern, SEM scan, and XPS pattern of the FeVO4 catalyst. These patterns demonstrate that the FeVO4 prepared by the hydrothermal method has high purity and exhibits a nanorod-like microstructure.

[0037] II. FeVO4-MgH2 Composite Hydrogen Storage Materials The following test experiments will be used to verify the influence of the FeVO4-MgH2 composite hydrogen storage material on the hydrogen storage performance in this scheme.

[0038] The MgH2-3FeVO, MgH2-6FeVO, and MgH2-9FeVO mentioned in the figure and below refer to hydrogen storage materials doped with 3%, 6%, and 9% FeVO4 catalyst, respectively.

[0039] 1. Hydrogen absorption performance at different temperatures Figure 4 (a) shows the isothermal hydrogen absorption curves of hydrogen storage materials doped with 0%, 3%, 6%, and 9% catalyst, respectively, at 200 °C. As can be seen from the figure, the hydrogen absorption rate is significantly increased under the condition of FeVO4 doping. After approximately 6 min of reaction, the hydrogen absorption capacities of MgH2-3FeVO4, MgH2-6FeVO4, and MgH2-9FeVO4 reached 6.13 wt%, 5.84 wt%, and 4.82 wt%, respectively, while the hydrogen absorption capacity of pure MgH2 without catalyst doping was only 1.97 wt%. The reaction rates of the first three are several times higher than the latter, indicating that the hydrogen absorption rate of the catalyst-doped composite materials is significantly improved at 200 °C.

[0040] Figure 4 (b) shows the isothermal hydrogen absorption curves of hydrogen storage materials doped with 3%, 6%, and 9% catalyst at 150 °C. It is easy to see from the figure that the hydrogen absorption rates of the three composite materials with different doping ratios are basically the same. The hydrogen absorption capacity almost reaches the maximum within 6 minutes of the reaction. The hydrogen absorption capacities of MgH2-3FeVO4, MgH2-6FeVO4, and MgH2-9FeVO4 are 5.61 wt%, 4.98 wt%, and 4.69 wt%, respectively.

[0041] Figure 4(c) shows the isothermal hydrogen absorption curves of hydrogen storage materials doped with 3%, 6%, and 9% catalyst, respectively, at 100 °C. It can be seen that the hydrogen absorption curves of MgH2-6FeVO and MgH2-9FeVO basically overlap at this time. At about 6 min, the hydrogen absorption reaches 4.56 wt%, while the hydrogen absorption of MgH2-3FeVO is 3.97 wt%. After about 10 min of reaction, the hydrogen absorption of MgH2-3FeVO exceeds that of MgH2-6FeVO and MgH2-9FeVO. After 60 min of reaction, the hydrogen absorption of MgH2-3FeVO is as high as 5.48 wt%, while the hydrogen absorption of MgH2-6FeVO and MgH2-9FeVO is about 5.03 wt%.

[0042] By comparing the hydrogen absorption behavior of undoped and magnesium-based composites with different FeVO4 doping ratios (3%, 6%, and 9%) at 100℃, 150℃, and 200℃, it was found that the introduction of FeVO4 not only effectively improved the hydrogen absorption rate but also increased the hydrogen storage capacity. Among them, the composite with a doping amount of 3wt% exhibited the optimal hydrogen absorption rate, making it the best choice for balancing kinetics and capacity.

[0043] In summary, the advantages of this scheme in hydrogen absorption performance are as follows (taking 3% catalyst doping at 200℃ as an example): 1) Low hydrogen absorption temperature: Compared with existing hydrogen storage materials that use rare earth high-entropy alloys as catalysts, which can only achieve a hydrogen absorption of 6.13wt% at 320℃, this solution can achieve the same hydrogen absorption at only 200℃, significantly reducing the hydrogen absorption temperature by as much as 37.5%.

[0044] 2) Fast hydrogen absorption rate: To achieve the same hydrogen absorption rate of 6.13 wt%, hydrogen storage materials using rare earth high-entropy alloy as catalyst require 120 minutes, while this solution only requires 6 minutes, significantly increasing the hydrogen absorption rate by up to 20 times.

[0045] 2. Hydrogen release performance at different temperatures Figure 5 (d) shows the isothermal hydrogen desorption curves of four composite materials with different doping ratios at 300 °C. It is easy to see that at this temperature, the hydrogen desorption rate of the catalyst-doped composite material is much greater than that of pure MgH2. After about 6 min of reaction, the hydrogen desorption of the two composite materials doped with 3% and 6% FeVO4 catalyst both exceeded 7 wt%, and the hydrogen desorption of the 9% doped composite material also exceeded 6%, while the hydrogen desorption of the undoped composite material was only 0.17 wt%. Among the three catalyst-doped components, the hydrogen desorption rate and hydrogen desorption of the 3% and 6% doped components were significantly better than those of the 9% doped component.

[0046] Figure 5(e) shows the isothermal hydrogen desorption curves of the composite materials with three doping ratios at 275 °C. The figure reveals that the hydrogen desorption of MgH2-3FeVO is greater than that of MgH2-6FeVO and MgH2-9FeVO. After 60 min of reaction, the hydrogen desorption of MgH2-3FeVO is approximately 6.65 wt%, MgH2-6FeVO is 6.48 wt%, and MgH2-9FeVO is 6.03 wt%. All three exhibit high hydrogen desorption rates, exceeding 5.0 wt% within 6 min.

[0047] Figure 5 (f) shows the isothermal hydrogen desorption curves of the composite materials with three doping ratios at 250 °C. It can be clearly seen from the curves that MgH2-3FeVO has the largest hydrogen desorption capacity, which is 6.31 wt% after 30 min of reaction, which is significantly higher than 5.66 wt% of MgH2-6FeVO. MgH2-9FeVO has the worst hydrogen desorption capacity, with a hydrogen desorption capacity of only 5.30 wt%.

[0048] By examining the hydrogen release performance of hydrogen storage materials with different doping ratios at different temperatures, it was found that the 3% and 6% FeVO4 catalysts exhibited better hydrogen release performance at temperatures above 275℃. At 250℃, the 3% FeVO4 catalyst still achieved a hydrogen release of 6.31 wt%, demonstrating its ability to maintain high hydrogen release even at low temperatures.

[0049] In summary, the hydrogen desorption performance advantages of this scheme are as follows (taking a 3% catalyst doping as an example): 1) Low hydrogen release temperature: Compared with existing hydrogen storage materials that use rare earth high entropy alloys as catalysts, which can only achieve a hydrogen release of 6.1 wt% at 340℃, this solution can achieve a higher hydrogen release of 6.31 wt% at only 250℃, significantly reducing the hydrogen release temperature by as much as 26.4%.

[0050] 2) High hydrogen release: At 300℃, the maximum hydrogen release of this scheme can reach about 7wt%, while the hydrogen storage material using rare earth high entropy alloy as catalyst can only reach 5.95 wt%, thus increasing the hydrogen release by 17.6%.

[0051] 3) Fast hydrogen release rate: This scheme can achieve a hydrogen release rate of 7 wt% in just 6 minutes at 300℃, while hydrogen storage materials using rare earth high-entropy alloys as catalysts require 25 minutes and 340℃ to reach 6.1 wt%. Therefore, this scheme increases the hydrogen release rate by at least 4 times at a relatively low temperature.

[0052] Therefore, in summary Figure 4 , Figure 5 The hydrogen storage materials with different FeVO4 doping ratios show that the addition of FeVO4 catalyst can greatly improve the hydrogen absorption and desorption performance of the hydrogen storage materials. However, excessive addition ratio can lead to material agglomeration, a decrease in specific surface area, and a reduction in the effective contact area between the FeVO4 catalyst and hydrogen, thus resulting in a decrease in the hydrogen storage capacity of the system. Among them, the hydrogen storage material with a 3% FeVO4 doping ratio achieves the optimal hydrogen storage performance.

[0053] 3. Cyclic stability Figure 6 The isotherm curve is obtained from 5 hydrogen absorption and desorption cycles of MgH2-3FeVO at 300 °C.

[0054] The horizontal axis represents time, and the vertical axis represents hydrogen capacity, marking the first to fifth cycles sequentially. Each cycle includes one hydrogen absorption and one hydrogen release, which can be used to assess the cycle stability, reversibility, and reaction kinetics of MgH2-3FeVO. As shown in the figure, at 300℃, the various hydrogen absorption and release curves of the material are very similar, with almost no hydrogen capacity decay observed. The maximum hydrogen absorption is approximately 6 wt%, and the maximum hydrogen release remains above 7 wt%, indicating that MgH2-3FeVO exhibits excellent cycle stability after five consecutive hydrogen absorption and release cycles. Compared to other traditional magnesium-based hydrogen storage materials that suffer from performance degradation at high temperatures, MgH2-3FeVO demonstrates a significant advantage: it maintains stable hydrogen storage performance at high temperatures without experiencing severe capacity decay. Furthermore, the graph shows that its hydrogen absorption and release curves are very steep, indicating that it can achieve rapid hydrogen absorption and release. Simultaneously, during each hydrogen absorption / release cycle, its hydrogen absorption / release curves are nearly symmetrical, without any obvious plateau drift or asymmetry, meaning this material exhibits excellent reaction reversibility. Reaction reversibility is a crucial parameter for evaluating the performance of magnesium-based hydrogen storage materials, referring to whether irreversible changes occur during cycling, i.e., whether the amount of hydrogen absorbed and released remains equal in magnitude and opposite in direction before and after cycling under the same material state. Based on the above reasons, MgH₂-3FeVO₄ exhibits not only a fast reaction rate and good reversibility at 300℃ but also a high capacity retention rate. Therefore, doping MgH₂ with FeVO₄ can significantly improve its cycling stability at 300℃.

[0055] 4. Thermodynamic performance Figure 7(a) is the curve obtained by fitting using the Johnson-Mehl-Avrami-Kolmogorov method, which includes three temperatures (250 ℃, 275 ℃, and 300 ℃). Figure 7 (b) shows the dehydrogenation activation energy of the sample obtained by linear fitting using the Arrhenius equation. The dehydrogenation activation energy of MgH2-3FeVO is 87.61 KJ / mol, while that of pure MgH2 is 160–220 KJ / mol. Therefore, the doping of ferric vanadate reduces the dehydrogenation activation energy of MgH2 by approximately 50%, significantly increasing the rate of the dehydrogenation reaction. This indicates that Fe and V elements in ferric vanadate promote the dehydrogenation of MgH2, increasing the rate of the dehydrogenation reaction several times. This is because V in ferric vanadate can accelerate the breaking of the Mg-H bond, and the interface between MgH2 and FeVO4 can form a diffusion channel, accelerating the diffusion of hydrogen atoms.

[0056] 5. Catalytic mechanism XRD was used to analyze the phase composition of MgH2-3FeVO at different stages to identify the phases that may have a catalytic effect on the system.

[0057] Figure 8 The XRD diffraction patterns of the MgH2-3FeVO sample in three states—ball-milled, dehydrogenated, and rehydrogen-absorbed—are shown. The XRD pattern reveals that most diffraction peaks in the ball-milled MgH2-3FeVO sample are MgH2, indicating that the main phase is still MgH2. A composite diffraction peak appears at 45.9°, composed of both Fe and V2O3. This composite diffraction peak is also present in the dehydrogenated and rehydrogen-absorbed MgH2-3FeVO states, indicating that some FeVO4 has decomposed during ball milling, generating Fe and V2O3. These components exhibit good stability and maintain their morphology without significant change in subsequent processes. This suggests that Fe and V2O3 likely continue to participate in the subsequent dehydrogenation and rehydrogen-absorbing reactions, acting as catalysts in the process.

[0058] Furthermore, MgO diffraction peaks were detected in the MgH2-3FeVO samples after ball milling, dehydrogenation, and rehydrogen absorption. This is likely due to the reaction of the introduced O element in FeVO4 with Mg during ball milling to form MgO. Based on the above results, the entire catalytic reaction pathway of the MgH2-3FeVO system is presumably as follows: First, the chemical activity of FeVO4 and MgH2 is activated during ball milling. The Fe and V2O3 generated in situ from their reaction are stably present in the dehydrogenated and rehydrogen-absorbed states of MgH2-3FeVO. Fe and V2O3 participate in the dehydrogenation and rehydrogen absorption reactions. The presence of Fe effectively reduces the bond energy of the HH bond, thus accelerating the dissociation of H2 and speeding up the hydrogen absorption process. In addition, Fe can also act as a diffusion channel for hydrogen atoms, while V2O3 can accelerate the breaking of the Mg-H bond, thereby increasing the hydrogen release rate. In summary, Fe mainly plays a role in the dissociation and process of hydrogen molecules and provides a pathway for hydrogen atom diffusion, thus increasing the hydrogen absorption rate; while V₂O₃ mainly promotes the breaking of Mg-H bonds, increasing the dehydrogenation rate. The synergistic effect of the two makes this composite system exhibit excellent kinetic performance in both hydrogen absorption and dehydrogenation processes.

[0059] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A FeVO4-MgH2 composite hydrogen storage material, characterized in that: The catalyst comprises MgH2 and FeVO4, wherein the total mass of the FeVO4-MgH2 composite hydrogen storage material is 100%, and the mass fraction of FeVO4 is 3%; the preparation method of the FeVO4 catalyst includes the following steps: S01, Prepare FeCl3·6H2O and NH4VO3; SO2. Dissolve FeCl3·6H2O in deionized water and stir for 30-35 minutes to obtain solution A; SO3. Dissolve NH4VO3 in deionized water at 80℃ and stir to dissolve in a water bath at 80℃ to obtain solution B; S04. While stirring, slowly add solution B dropwise to solution A, and continue stirring for 30-40 minutes to obtain solution C; S05. After reacting solution C at 180-190℃ for 3-3.5h, cool to room temperature, centrifuge to collect the precipitate, wash the precipitate repeatedly, and dry it at 60-70℃ to obtain powder. S06. The powder obtained in S05 is calcined at 500-550℃ for 1.8-2.2h at a heating rate not exceeding 5℃ / min to obtain a rod-shaped FeVO4 catalyst.

2. The FeVO4-MgH2 composite hydrogen storage material according to claim 1, characterized in that: Includes the following steps: Prepare a catalyst with 97% MgH2 and 3% FeVO4 by mass, mix and ball-mill the two to obtain FeVO4-MgH2 composite hydrogen storage material.

3. The FeVO4-MgH2 composite hydrogen storage material according to claim 2, characterized in that: During ball milling, mill at 350-420 r / min, pause for 10 minutes after every 10 minutes of milling, and repeat 70-75 times.

4. The FeVO4-MgH2 composite hydrogen storage material according to claim 3, characterized in that: The molar ratio of FeCl3·6H2O and NH4VO3 is 1:

1.

5. The FeVO4-MgH2 composite hydrogen storage material according to claim 4, characterized in that: In S05, solution C is placed in a stainless steel reactor lined with polytetrafluoroethylene for reaction.

6. The FeVO4-MgH2 composite hydrogen storage material according to claim 5, characterized in that: The atmosphere during ball milling is an inert atmosphere.

7. The FeVO4-MgH2 composite hydrogen storage material according to any one of claims 1-6 is applied in the field of hydrogen storage materials.

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