Long-life magnesium-based hydrogen storage material and preparation method thereof

Abstract

The application provides a long-life magnesium-based hydrogen storage material and a preparation method thereof. The magnesium-based hydrogen storage material takes a magnesium hydride as a matrix, is prepared by introducing ZrH2 / C and / or TiO2 as a catalyst through ball milling, and the content of the catalyst is 5wt%. The magnesium-based hydrogen storage material is subjected to hydrogen absorption and release cycles at 300 DEG C, and can release 7.0wt.% H2 within 6min after 1000 cycles, and has very low capacity attenuation. Compared with other magnesium-based hydrogen storage materials, the application solves the problems of short cycle life and easy particle agglomeration of the previous catalytically modified magnesium-based materials, has the advantages of simple preparation process, low hydrogen absorption and release temperature, low hydrogen absorption pressure, long cycle life and excellent kinetic performance, and has important application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the field of solid-state hydrogen storage, and particularly relates to a long-life magnesium-based hydrogen storage material and a preparation method thereof. BACKGROUND

[0002] Hydrogen energy is a clean energy with hydrogen as a carrier. Hydrogen is widely distributed, has abundant reserves, high energy density, and no pollution, and is considered to be the most potential energy carrier to replace fossil energy in the future. However, hydrogen storage is still a bottleneck for the development of hydrogen energy. Among the many developed hydrogen storage materials, MgH2 is considered to be one of the most promising hydrogen storage materials due to its high hydrogen storage capacity (7.6wt.%), low price, abundant resource storage, and environmental compatibility. However, compared with traditional hydrogen storage alloys, the hydrogenated magnesium hydrogen storage material has problems such as high hydrogen absorption and desorption temperature, poor kinetic performance, and short cycle life. The hydrogen absorption and desorption temperature is usually above 350℃ to achieve the expected hydrogen storage density, and the MgH2 particles are prone to agglomeration during repeated hydrogen charging and discharging, which leads to a sharp decline in performance, causing some obstacles to the commercial development of magnesium-based hydrogen storage materials.

[0003] In the past few decades, many methods have been adopted to improve the hydrogen storage properties of MgH2. Among them, the method of adding catalysts can improve the kinetic performance of MgH2 by providing active nucleation sites and providing a fast channel for H atom diffusion, thereby reducing the hydrogen absorption and desorption temperature. Although current research on the catalytic modification of MgH2 has made good progress in reducing the hydrogen absorption and desorption temperature of MgH2 and improving its kinetic performance, the cycle performance has not been significantly improved. For example, the addition of Ti(Nb)O2 can catalyze MgH2 to release 6wt.% of H2 within 12 minutes at 225℃, but the capacity decreases to 5.39wt.% after 50 cycles at 250℃ [Dan L., Wang H., Yang X., et al. ACS Appl. Mater. Interfaces 2023, 15(25), 30372-30382.]; the addition of 5wt.% of N-NaTiO can catalyze MgH2 to completely release hydrogen within 20 minutes at 300℃, but the hydrogen release time is extended to 60 minutes after 250 cycles [Li J., Zou R., Cui Y., et al. Chemical Engineering Journal 2023, 470, 144259.]. Therefore, it is necessary to provide a preparation method of a hydrogen storage material with high hydrogen storage capacity, fast kinetics, and long cycle life. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides a long-life magnesium-based hydrogen storage material and a preparation method thereof, which has excellent cycle stability and solves the problem that the hydrogen storage material in the prior art cannot have high hydrogen storage capacity, fast kinetics and long cycle life.

[0005] To achieve the above-mentioned object, the present application adopts the following technical scheme:

[0006] The preparation method of the long-life magnesium-based hydrogen storage material comprises the following steps:

[0007] S1 mixing ZrH2 and graphene under an argon atmosphere to obtain a mixture, and pouring the mixture into a ball mill tank;

[0008] S2 ball milling the mixture in S1 by using a planetary ball milling method, and obtaining a ZrH2 / C catalyst after ball milling;

[0009] S3 ball milling TiO2 under a vacuum condition by using a plasma ball milling method, and obtaining a PTiO2 catalyst after ball milling;

[0010] S4 mixing magnesium hydride, ZrH2 / C and PTiO2 under an argon atmosphere, and pouring the mixture into a ball mill tank;

[0011] S5 ball milling the mixture in S4 on a planetary ball mill under a hydrogen atmosphere to obtain a MgH2-3ZrH2 / C-2PTiO2 composite hydrogen storage material.

[0012] Preferably, in the step S1, the atomic ratio of Zr to C in ZrH2 and graphene is 5:1.

[0013] Preferably, in the step S2, the ball milling rotation speed is 250 rpm, the ball-to-material ratio is 40:1, and the ball milling time is 25 h.

[0014] Preferably, in the step S2, the ball milling is performed for 25 h, and during the ball milling process, mechanical energy is converted into part of heat energy, so as to prevent the system temperature from being too high, and therefore, the instrument is stopped for 15 min every 30 min of operation.

[0015] Preferably, in the step S3, the ball milling rotation speed is 1320 rpm, the ball-to-material ratio is 100:1, and the ball milling time is 2 h.

[0016] Preferably, in the step S4, the content of each component is 95 wt.% magnesium hydride, 3 wt.% ZrH2 / C and 2 wt.% PTiO2.

[0017] Preferably, as a preferred embodiment, in the step S5, the hydrogen atmosphere is 1.5 MPa.

[0018] Another object of the present application is to provide a magnesium-based hydrogen storage material prepared by the aforementioned preparation method.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The raw materials used in the present application, magnesium hydride powder, zirconium hydride powder, titanium dioxide powder and graphene, are commercial products, and the raw materials are easy to obtain; the mechanical ball milling preparation process is simple, convenient to operate and fast in material synthesis.

[0021] (2) The method of adding a catalyst can improve the kinetic performance of MgH2 by providing active nucleation sites and providing a fast channel for the diffusion of H atoms, but in the cycling process, the phase interface of the catalyst combined with MgH2 may be destroyed, resulting in catalyst deactivation. By comparison, it can be found that the PTiO2 prepared in the present application as a catalyst can improve the dehydrogenation kinetics of MgH2; ZrH2 / C as a catalyst can exist stably during the cycling process and can stabilize the structure of MgH2 and the dehydrogenation product, thereby significantly prolonging the cycling life of MgH2. Therefore, by simultaneously introducing ZrH2 / C and PTiO2 into MgH2, the material successfully cycles hydrogen absorption / desorption 1000 times at 300℃, and the capacity is still as high as 7.0wt.%, solving the problems of short cycling life and easy particle agglomeration of the previously catalytically modified magnesium hydride, and having potential application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure shows the dehydrogenation kinetic curve of the sample after treatment in Example 1 of the present application at 300℃;

[0023] Figure 2 The figure shows the dehydrogenation kinetic curve of the sample after treatment in Example 1 of the present application at 300℃;

[0024] Figure 3 The figure shows the XRD pattern of the MgH2-3ZrH2 / C-2PTiO2 composite sample prepared in Example 1 of the present application and the dehydrogenated sample after cycling;

[0025] Figure 4 The figure shows the dehydrogenation kinetic curve of the sample after treatment in Example 2 of the present application at 300℃;

[0026] Figure 5 The figure shows the dehydrogenation kinetic curve of the sample after treatment in Example 2 of the present application at 300℃;

[0027] Figure 6The hydrogen desorption kinetics curve of the sample after the treatment of the embodiment 3 of the present application at 300℃ is shown.

[0028] Figure 7 The single cycle hydrogen desorption kinetics curve of the sample after the treatment of the embodiment 3 of the present application at 300℃ in the cycle is shown. DETAILED DESCRIPTION

[0029] For better illustrating the purpose, technical scheme and advantages of the present application, the present application will be further explained in combination with specific embodiments.

[0030] I. Embodiment 1

[0031] The raw materials are commercially available magnesium hydride powder, zirconium hydride powder, titanium dioxide powder and graphene.

[0032] A preparation method of a magnesium-based hydrogen storage material, comprising the following steps:

[0033] S1 In an argon atmosphere glove box, 4.4183g of ZrH2 and 0.5817g of graphene were weighed and poured into a ball mill jar for mixing, a planetary ball milling method was adopted, the ball-to-material ratio was 40:1, the ball milling speed was 250rpm, and the ball milling time was 25h, to obtain a ZrH2 / C catalyst.

[0034] S2 2g of TiO2 powder was weighed and poured into a ball mill jar, the ball-to-material ratio was 40:1, a plasma ball milling method was adopted under vacuum condition, the ball milling speed was 1320rpm, and the ball milling time was 2h, to obtain a PTiO2 catalyst.

[0035] S3 In an argon atmosphere glove box, 0.03g of ZrH2 / C, 0.02g of PTiO2 and 0.95g of MgH2 were weighed and poured into a ball mill jar, 1.5MPa of hydrogen was introduced into the ball mill jar, a planetary ball milling method was adopted, the ball milling speed was 400rpm, the ball-to-material ratio was 50:1, and the ball milling time was 10h, to obtain a composite sample marked as MgH2-3ZrH2 / C-2PTiO2.

[0036] HyEnergy PCTPro 2000 was adopted to test the hydrogen desorption performance of the sample in the cycle.

[0037] The hydrogen desorption kinetics performance test method was as follows: about 70mg of MgH2-3ZrH2 / C-2PTiO2 composite sample was placed in a sample rod, vacuumizing was performed after the sample was installed, 3MPa of hydrogen was filled and heated, wherein the heating rate was 5℃ / min. When the temperature rose to 300℃, the hydrogen desorption kinetics performance test was started, wherein the hydrogen absorption hydrogen pressure was 2MPa, the hydrogen absorption time was 10min, and the hydrogen desorption initial hydrogen pressure was 0bar.

[0038] Figure 1The hydrogen release cycle curve of MgH2-3ZrH2 / C-2PTiO2 at 300℃ is shown in Figure 4, from which it can be seen that the capacity gradually increased from 6.6wt.% to 7.0wt.% in the first 50 cycles, and remained at 7.0wt.% after 1000 cycles. Figure 1

[0039] Figure 2 The isothermal hydrogen release kinetics curve of the composite hydrogen storage material per 100 cycles is shown in Figure 5, which shows that the hydrogen release rate first increased and then decreased, and the fastest release of 6.9wt.% H2 was achieved in 4min, and the release of 7.0wt.% H2 was always completed within 6min in the remaining stages, and the hydrogen release kinetics remained excellent even after 1000 cycles.

[0040] The composite sample of MgH2-3ZrH2 / C-2PTiO2 prepared in this embodiment and the sample after the hydrogen release cycle were subjected to XRD testing. The XRD pattern is shown in Figure 6, which shows that the phases of the composite sample mainly consisted of magnesium hydride, ZrH2 and TiO2, and the phases of the sample after the hydrogen release cycle mainly consisted of Mg, MgO and ZrH2, indicating that the sample was in a completely dehydrogenated state. Figure 3

[0041] II. Example 2

[0042] The composite sample was prepared according to the same preparation method as in Example 1, and the mixture was 0.05g ZrH2 / C and 0.95g MgH2. The prepared composite sample was marked as MgH2-5ZrH2 / C. The composite sample prepared in Example 2 was subjected to hydrogen release cycle performance testing.

[0043] The hydrogen release cycle kinetics performance testing method was as follows: about 70mg of the MgH2-5ZrH2 / C composite sample was placed in a sample rod, vacuum was drawn after the sample was installed, 3MPa of hydrogen was filled and heated, and the heating rate was 5℃ / min. When the temperature reached 300℃, the hydrogen release cycle kinetics performance testing was started, and the hydrogen absorption pressure was 2MPa, the hydrogen absorption time was 10min, and the initial hydrogen pressure for hydrogen release was 0bar.

[0044] Figure 4 The hydrogen release cycle curve of MgH2-5ZrH2 / C at 300℃ is shown in Figure 8, from which it can be seen that the first hydrogen release capacity reached 6.6wt.%, and the capacity gradually increased to 7.0wt.% during the cycle process.

[0045] Figure 5 The isothermal hydrogen release kinetics curve of the composite hydrogen storage material per 5 cycles is shown in Figure 9, which shows that the hydrogen release rate first increased and then decreased, and the fastest release of 6.6wt.% H2 was achieved in 6min, and the hydrogen release was always completed within 9min in the remaining stages.

[0046] III. Example 3​​

[0047] The composite sample was prepared by the same method as in Example 1, the mixture was 0.05 g PTiO2, 0.95 g MgH2, and the prepared composite sample was marked as MgH2-5PTiO2. The cyclic hydrogen release performance test was conducted on the composite sample prepared in Example 3.

[0048] The hydrogen release cycle kinetics performance test method was as follows: about 70 mg MgH2-5PTiO2 composite sample was placed in a sample rod, vacuumizing was conducted after the sample was installed, 3 MPa hydrogen was filled and heated, the heating rate was 5°C / min. When the temperature rose to 300°C, the hydrogen release cycle kinetics performance test was started, the hydrogen absorption hydrogen pressure was 2 MPa, the hydrogen absorption time was 10 min, and the hydrogen release initial hydrogen pressure was 0 bar.

[0049] Figure 6 The hydrogen release cycle kinetics performance test method was as follows: about 70 mg MgH2-5PTiO2 composite sample was placed in a sample rod, vacuumizing was conducted after the sample was installed, 3 MPa hydrogen was filled and heated, the heating rate was 5°C / min. When the temperature rose to 300°C, the hydrogen release cycle kinetics performance test was started, the hydrogen absorption hydrogen pressure was 2 MPa, the hydrogen absorption time was 10 min, and the hydrogen release initial hydrogen pressure was 0 bar.

[0050] Figure 7 The hydrogen release cycle kinetics performance test method was as follows: about 70 mg MgH2-5PTiO2 composite sample was placed in a sample rod, vacuumizing was conducted after the sample was installed, 3 MPa hydrogen was filled and heated, the heating rate was 5°C / min. When the temperature rose to 300°C, the hydrogen release cycle kinetics performance test was started, the hydrogen absorption hydrogen pressure was 2 MPa, the hydrogen absorption time was 10 min, and the hydrogen release initial hydrogen pressure was 0 bar.

[0051] As described above, the application can be well implemented, the above examples are only part of the examples of the application, and are not used to limit the implementation range of the application; any equivalent change and modification made according to the content of the application are covered in the range required by the claims of the application.

Claims

1. A method for preparing a long-life magnesium-based hydrogen storage material, characterized in that, The method comprises the following steps: S1 mixing ZrH2 and graphene under argon atmosphere to obtain a mixture, and pouring the mixture into a ball mill tank; S2 ball milling the mixture in S1 by using a planetary ball mill to obtain a ZrH2 / C catalyst; S3 ball milling TiO2 under vacuum by using a plasma ball mill to obtain a PTiO2 catalyst; S4 mixing MgH2, ZrH2 / C and PTiO2 under argon atmosphere, and pouring the mixture into a ball mill tank; S5 ball milling the mixture in S4 on a planetary ball mill under hydrogen atmosphere to obtain a MgH2-3ZrH2 / C-2PTiO2 composite hydrogen storage material; In the step S4, the content of each component is 95 wt.% MgH2, 3 wt.% ZrH2 / C and 2 wt.% PTiO2.

2. The production method according to claim 1, characterized by, In the step S1, the atomic ratio of Zr to C in ZrH2 and graphene is 5:

1.

3. The production method according to claim 1, characterized by, In the step S2, the ball milling speed is 250 rpm, the ball-to-material ratio is 40:1, and the ball milling time is 25 h, and the ball milling is stopped for 15 min every 30 min.

4. The production method according to claim 1, characterized by, In the step S3, the ball milling speed is 1320 rpm, the ball-to-material ratio is 100:1, and the ball milling time is 2 h.

5. The production method according to claim 1, characterized by, In the step S5, the hydrogen atmosphere is 1.5 MPa.

6. A magnesium-based hydrogen storage material prepared by the preparation method according to any one of claims 1-5.

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