Hydrogen storage alloy and industrial production method thereof

Abstract

This invention discloses a hydrogen storage alloy and its industrial-scale preparation method, belonging to the field of magnesium-based solid-state hydrogen storage materials. The raw materials used are magnesium-nickel alloy ingots, pure magnesium, magnesium rare-earth alloy ingots, and flux. This invention employs a specific preparation sequence, combined with mechanical processing, pulverization, and hydrogenation, to prepare a high-performance hydrogen storage alloy. Each unit operation in the process flow of this invention is easily scaled up, has high compatibility with existing metallurgical and mechanical processing industries, and possesses promising prospects for industrial application. The method of this invention effectively solves the problems of poor safety and high equipment cost in the hydrogen storage alloy smelting process; low pulverization efficiency, easy introduction of impurities, and inherent risks associated with traditional ball milling methods; and difficulties, long cycles, and high energy consumption in the initial activation of materials.

Description

Technical Field

[0001] This invention relates to the field of magnesium-based solid hydrogen storage materials, and more specifically to a hydrogen storage alloy and its industrial preparation method. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, faces key technological bottlenecks in its storage and transportation, hindering its large-scale application. Magnesium-based hydrogen storage alloys are considered one of the most promising solid-state hydrogen storage materials due to their high hydrogen storage capacity (theoretically up to 7.6 wt%), abundant resources, and low cost.

[0003] However, the industrial application of magnesium-based hydrogen storage alloys faces two major challenges:

[0004] Flammability issues during preparation: Magnesium is extremely reactive during smelting and subsequent processing, and is easily oxidized or even burned. Traditional smelting requires inert gas protection or a vacuum environment, which involves complex equipment and high costs, making it difficult to achieve large-scale, low-cost industrial production.

[0005] Activation challenges: A dense oxide film forms on the surface of dense magnesium ingots or blocks, hindering the dissociation of hydrogen molecules and the diffusion of hydrogen atoms, making activation very difficult. It usually requires extremely high temperatures (>350℃) and pressures (>3MPa) as well as multiple hydrogen absorption and desorption cycles, which is time-consuming, energy-intensive, and inefficient.

[0006] Currently, although some studies have used mechanical ball milling to prepare magnesium powder, this method has high energy consumption, low yield, is prone to introducing impurities, and poses safety hazards, making it difficult to meet the needs of industrialization.

[0007] Therefore, it is of great significance to develop a simple, safe, reliable, low-cost method suitable for industrial-scale preparation and activation of magnesium-based hydrogen storage alloys. Summary of the Invention

[0008] To address the problems in the industrial-scale preparation of magnesium-based hydrogen storage materials, such as poor safety and high equipment costs during the smelting process; low efficiency, easy introduction of impurities, and risks associated with traditional ball milling; and difficulties, long cycles, and high energy consumption in the initial activation of materials, this invention provides a simple, safe, reliable, and low-cost industrial-scale preparation method. This method achieves efficient, safe, and large-scale production of magnesium-based hydrogen storage alloys through flux flame retardancy, mechanical cutting for chip preparation, and forced hydrogenation in a reaction vessel.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A hydrogen storage alloy includes a magnesium-nickel alloy ingot, pure magnesium, a magnesium rare earth alloy ingot, and a flux; The mass ratio of magnesium, nickel and rare earth elements in the hydrogen storage alloy is 83-88:8-12:4-6. The amount of flux used is 1.5% of the total mass of magnesium-nickel alloy ingots, pure magnesium and magnesium rare earth alloy ingots.

[0010] Furthermore, the magnesium-nickel alloy ingot is Mg80Ni20; the magnesium rare earth alloy ingot is any one of Mg70Ce30, Mg70Nd30, Mg80La20, and Mg80Gd20.

[0011] Furthermore, the flux is RJ-2.

[0012] This invention also provides an industrial-scale preparation method for the above-mentioned hydrogen storage alloy, comprising the following steps: (1) Weigh each raw material according to the above dosage; (2) Divide the flux into three equal parts, then put the magnesium-nickel alloy ingot into a graphite crucible and cover the magnesium-nickel alloy ingot with the first part of flux. Place the crucible into an induction heating furnace and heat until it melts into a liquid state. (3) After adding the magnesium rare earth alloy ingot to the crucible, add the second part of flux and heat it again to melt it into a liquid state. Then add pure magnesium and the third part of flux, heat it to a liquid state and stir it evenly. Finally, pour the alloy material in the crucible into the graphite mold to obtain the alloy rod. (4) The alloy rod is mechanically crushed and then the resulting alloy scrap is loaded into an alumina crucible. The alumina crucible is placed in a high-temperature and high-pressure reactor, sealed, and then evacuated and filled with hydrogen 2-3 times. The parameters are adjusted. The conditions for hydrogenation activation are a temperature of 370-390℃ and a hydrogen pressure of 4-5MPa. The hydrogenation activation of the alloy can be completed by maintaining these conditions for 10-15 hours, and a hydrogen storage alloy is obtained.

[0013] Furthermore, the induction heating furnace mentioned in step (2) needs to be heated to 750-800℃ until the magnesium alloy and pure magnesium raw materials are completely melted into a liquid state.

[0014] Furthermore, the induction heating furnace described in step (3) needs to be heated to 750-800°C until the material is completely melted into a liquid state; The graphite mold needs to be preheated to 200°C.

[0015] Furthermore, the machining and crushing method described in step (4) is to set the spindle speed to 500 rpm / min, the feed rate to 0.1 cm, the cutting speed to 0.2 m / min, and the tool angle to 25° to obtain alloy chips of uniform size.

[0016] The beneficial effects of this invention are as follows: (1) The present invention uses a low-cost flux to replace the expensive vacuum or high-purity inert gas protection system, which greatly reduces the cost of smelting equipment and the difficulty of operation, and is very suitable for large-scale industrial production.

[0017] (2) Mechanical cutting has a much higher crushing efficiency than mechanical ball milling, and can be used for continuous mass production. The chips produced by cutting have a fresh and clean surface, and avoid the contamination of impurities and the risk of spontaneous combustion caused by ball milling.

[0018] (3) This invention utilizes the highly active surface generated by mechanical processing, combined with the strengthening effect of the high temperature and high pressure reactor, to achieve "one-step in-situ hydrogenation activation", eliminating the cumbersome multi-round hydrogen absorption and desorption cycle activation process of traditional methods, significantly shortening the production cycle and reducing energy consumption.

[0019] (4) Each unit operation of the process flow of the present invention (smelting-casting-machining-hydrogenation) is easy to scale up, has high compatibility with existing metallurgical and mechanical processing industries, and has prospects for industrial application. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the industrial-scale preparation method of magnesium-based hydrogen storage alloy of the present invention; Figure 2 This is a SEM image of magnesium alloy fragments obtained by mechanical cutting in Embodiment 1 of the present invention. Figure 3 The TPD hydrogen desorption curve of the Mg-Ni-Ce hydrogen storage alloy prepared in Example 1 of this invention after hydrogenation; Figure 4 The TPD hydrogen desorption curve of the Mg-Ni-Nd hydrogen storage alloy prepared in Example 2 of this invention after hydrogenation; Figure 5 The TPD hydrogen desorption curve of the Mg-Ni-Gd hydrogen storage alloy prepared in Example 3 of this invention after hydrogenation; Figure 6 The TPD hydrogen desorption curve of the Mg-Ni-La hydrogen storage alloy prepared in Example 4 of this invention after hydrogenation; Figure 7 The TPD hydrogen desorption curve of MgH2 in Comparative Example 1 of this invention; Figure 8 The TPD hydrogen desorption curve is shown for the hydrogen storage alloy of Comparative Example 3 of this invention after hydrogenation. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 The industrial-scale preparation method of hydrogen storage alloys includes the following steps: (1) 150g of Mg80Ni20 alloy, 112.75g of pure magnesium (the expected Mg burn-off rate is 5%), 50g of Mg70Ce30 alloy; the total calculated amount is 312.75g, and 4.69g of 1.5% flux RJ-2 is weighed. (2) Divide the flux into three equal parts, then put Mg80Ni20 into a graphite crucible and cover the magnesium-nickel alloy ingot with the first part of flux. Place the crucible into an induction heating furnace and heat it to 760°C to a molten liquid state. (3) After adding Mg70Ce30 ingots to the crucible, add the second part of flux and heat again to 760°C to liquid state. Then add pure magnesium and the third part of flux, heat to liquid state and stir evenly. Finally, pour the alloy material in the crucible into the graphite mold (the graphite mold is preheated to 200°C in advance) to obtain alloy rods. (4) The alloy bar was mechanically crushed. The spindle speed was set to 500 rpm / min, the feed rate to 0.1 cm, the cutting speed to 0.2 m / min, and the tool angle to 25°, resulting in uniformly sized Mg-Ni-Ce alloy chips. The obtained Mg-Ni-Ce alloy chips were tested using a scanning electron microscope (SEM) to obtain SEM images and EDS results. The SEM results showed that the chip size was greater than 500 micrometers, but there were cracks, which had a certain effect on hydrogen absorption and desorption. The EDS results showed that Mg, Ni, and Ce were uniformly distributed in the alloy, indicating that segregation was not serious during the smelting process and the alloy composition was uniform. Figure 2 As shown.

[0023] (5) The obtained alloy fragments are loaded into a corundum crucible. The corundum crucible is placed in a high-temperature and high-pressure reactor, sealed, and then evacuated and filled with hydrogen three times. The parameters are adjusted to a temperature of 380℃ and a hydrogen pressure of 4.5MPa. The hydrogenation activation of the alloy is completed after 12 hours, and Mg-Ni-Ce hydrogen storage alloy is obtained.

[0024] A Mg-Ni-Ce hydrogen storage alloy was used, and its TPD (Total Hydrogen Desorption / Potential) was tested using a PCT hydrogen adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The test results showed a hydrogen desorption capacity of 5.94 wt%, an initial hydrogen desorption temperature of 234℃, and a peak dehydrogenation temperature of 264℃. Dehydrogenation was complete within 30 minutes, demonstrating good dehydrogenation kinetics, significantly improved compared to pure magnesium. Figure 3 As shown.

[0025] Example 2 The technical solution is basically the same as that in Example 1, except that the Mg70Ce30 alloy is replaced with the Mg70Nd30 alloy to form a Mg-Ni-Nd hydrogen storage alloy.

[0026] A Mg-Ni-Nd hydrogen storage alloy was used, and its TPD (Total Hydrogen Desorption / Potential) was tested using a PCT hydrogen adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The test results showed a hydrogen desorption capacity of 5.62 wt%, an initial hydrogen desorption temperature of 254℃, and a peak dehydrogenation temperature of 281℃. Main phase dehydrogenation was complete within 30 minutes, demonstrating good dehydrogenation kinetics, significantly improved compared to pure magnesium. Figure 4 As shown.

[0027] Example 3 The technical solution is basically the same as that in Example 1, except that the Mg70Ce30 alloy is replaced with the Mg80Gd20 alloy to form a Mg-Ni-Gd hydrogen storage alloy.

[0028] A Mg-Ni-Gd hydrogen storage alloy was used, and its TPD (Total Hydrogen Desorption / Potential) was tested using a PCT hydrogen adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The test results showed a hydrogen desorption capacity of 5.66 wt%, an initial hydrogen desorption temperature of 271℃, and a peak dehydrogenation temperature of 328℃. Main phase dehydrogenation was complete within 30 minutes, demonstrating good dehydrogenation kinetics, significantly improved compared to pure magnesium. Figure 5 As shown.

[0029] Example 4 The technical solution is basically the same as that in Example 1, except that the Mg70Ce30 alloy is replaced with the Mg80La20 alloy to form a Mg-Ni-La hydrogen storage alloy.

[0030] A Mg-Ni-La hydrogen storage alloy was used, and its TPD (Total Hydrogen Desorption / Potential) was tested using a PCT hydrogen adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The test results showed a hydrogen desorption capacity of 5.89 wt%, an initial hydrogen desorption temperature of 265℃, and a peak dehydrogenation temperature of 310℃. Main phase dehydrogenation was complete within 30 minutes, demonstrating good dehydrogenation kinetics, significantly improved compared to pure magnesium. Figure 6 As shown.

[0031] Comparative Example 1 The TPD of MgH2 was tested using a PCT hydrogen adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The results showed a hydrogen release capacity of 6.60 wt%, an initial hydrogen release temperature of 300℃, a peak dehydrogenation temperature of 404℃, and poor dehydrogenation kinetics, with main phase dehydrogenation occurring between 130 and 200 minutes. Figure 7 As shown.

[0032] Comparative Example 2 The technical solution is basically the same as that in Example 1, except that no flux is added. The result shows that a large amount of magnesium is burned off, and hydrogen storage material cannot be obtained.

[0033] Comparative Example 3 According to the technical solution of Example 1, All materials were added out of order; all raw materials were directly mixed and then melted and cast with flux. During the experiment, some magnesium was burned off, and segregation also occurred. Hydrogen storage performance was tested using a PCT hydrogen storage adsorption analyzer. The temperature was set to 550℃ for 250 minutes. The test results showed a hydrogen release capacity of 5.98 wt%, an initial hydrogen release temperature of 211℃, and a peak dehydrogenation temperature of 297℃. Compared to Example 1, the initial temperature was 23℃ lower, and the peak hydrogen release temperature was 33℃ higher. The dehydrogenation was a two-step process, and the kinetics of the two-step dehydrogenation showed that complete dehydrogenation took approximately 50 minutes. Compared to Example 1, the kinetic effect of Example 1 was superior to that of Comparative Example 3.

[0034] Table 1. Test results of hydrogen storage alloys in different embodiments and comparative examples.

[0035] The method of the present invention is not only applicable to the above-mentioned alloy materials, but can also be used to prepare other types of hydrogen storage alloys, such as multi-element magnesium-based hydrogen storage alloys and Ti-based hydrogen storage alloys. For Ti-based alloys, only the hydrogenation and testing parameters need to be modified.

[0036] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydrogen storage alloy, characterized in that, Including magnesium-nickel alloy ingots, pure magnesium, magnesium rare earth alloy ingots, and flux; The mass ratio of magnesium, nickel and rare earth elements in the hydrogen storage alloy is 83-88:8-12:4-6. The amount of flux used is 1.5% of the total mass of magnesium-nickel alloy ingots, pure magnesium and magnesium rare earth alloy ingots.

2. The hydrogen storage alloy according to claim 1, characterized in that, The magnesium-nickel alloy ingot is Mg80Ni20; the magnesium rare earth alloy ingot is any one of Mg70Ce30, Mg70Nd30, Mg80La20, and Mg80Gd20.

3. A hydrogen storage alloy according to claim 1 or 2, characterized in that, The flux is RJ-2.

4. The industrial-scale preparation method of a hydrogen storage alloy according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Weigh each raw material according to the amount specified for the hydrogen storage alloy; (2) Divide the flux into three equal parts, then put the magnesium-nickel alloy ingot into a graphite crucible and cover the magnesium-nickel alloy ingot with the first part of flux. Place the crucible into an induction heating furnace and heat until it melts into a liquid state. (3) After adding the magnesium rare earth alloy ingot to the crucible, add the second part of flux and heat it again to melt it into a liquid state. Then add pure magnesium and the third part of flux, heat it to a liquid state and stir it evenly. Finally, pour the alloy material in the crucible into the graphite mold to obtain the alloy rod. (4) The alloy rod is mechanically crushed and then the resulting alloy scrap is loaded into an alumina crucible. The alumina crucible is placed in a high-temperature and high-pressure reactor, sealed, and then evacuated and filled with hydrogen 2-3 times. The parameters are adjusted. The conditions for hydrogenation activation are a temperature of 370-390℃ and a hydrogen pressure of 4-5MPa. The hydrogenation activation of the alloy can be completed by maintaining these conditions for 10-15 hours, and a hydrogen storage alloy is obtained.

5. The industrial-scale preparation method of a hydrogen storage alloy according to claim 4, characterized in that, The induction heating furnace mentioned in step (2) needs to be heated to 750-800℃ until the magnesium alloy and pure magnesium raw materials are completely melted into a liquid state.

6. The industrial-scale preparation method of a hydrogen storage alloy according to claim 4, characterized in that, The induction heating furnace mentioned in step (3) needs to be heated to 750-800℃ until the material is completely melted into a liquid state; The graphite mold needs to be preheated to 200°C.

7. The industrial-scale preparation method of a hydrogen storage alloy according to claim 4, characterized in that, The machining and crushing method described in step (4) is to set the spindle speed to 500 rpm / min, the feed rate to 0.1 cm, the cutting speed to 0.2 m / min, and the tool angle to 25° to obtain alloy chips of uniform size.

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