A cold-welding-free magnesium-based hydrolysis hydrogen production powder material and a preparation method thereof

Abstract

This invention belongs to the technical field of hydrolysis hydrogen production materials, specifically relating to a cold-welding-free magnesium-based hydrolysis hydrogen production powder material and its preparation method. The cold-welding-free magnesium-based hydrolysis hydrogen production powder material is composed of Mg in a mass ratio of 80-95:5-20. x Ca 1‑x It is composed of alloy hydride and expanded graphite; the value of x ranges from 0.7 to 1. In the preparation of powder materials, Mg... x Ca 1‑x After the alloy is pulverized, expanded graphite is added, and then the mixture is ball-milled to obtain Mg. x Ca 1‑x Alloy-expanded graphite powder is repeatedly activated and hydrogenated to obtain Mg. x Ca 1‑x Alloy hydride-expanded graphite composite material. The addition of expanded graphite can effectively suppress the cold welding phenomenon that occurs during ball milling, improve the powdering efficiency, and also effectively reduce the particle size and promote hydrogenation, thereby increasing the hydrogen production from hydrolysis. This is conducive to the large-scale industrial production of the material and has ideal application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrolysis hydrogen production materials, and particularly relates to a cold-weld-free magnesium-based hydrolysis hydrogen production powder material for hydrolysis hydrogen production and a preparation method thereof. BACKGROUND

[0002] Hydrogen energy is regarded as an ideal alternative energy due to its cleanliness and renewable advantage. However, the efficient, safe production, storage and transportation of hydrogen greatly limit the development of hydrogen energy. The hydrolysis hydrogen production technology of magnesium-based materials integrates the production, storage and transportation of hydrogen, and can realize online production of hydrogen at normal temperature and pressure, so it is a relatively ideal portable hydrogen source.

[0003] However, the hydrolysis hydrogen production of magnesium-based materials is affected by the by-product Mg(OH)2, which usually covers the surface of the material to form a passivation layer, hinders water from entering the inside of the particles, and thus reduces the hydrolysis conversion rate. Chinese patent CN103787273A discloses a "magnesium-calcium-based hydride powder for hydrolysis hydrogen production in a wide temperature range and a preparation method thereof", which contains components Ca4Mg3H 14 is easy to hydrolyze, and the by-product Ca(OH)2 is relatively easier to dissolve than Mg(OH)2, thus providing a channel for water to enter the inside of the particles, so it has more excellent hydrolysis hydrogen production performance than Mg and MgH2 at room temperature and low temperature. However, since magnesium and magnesium-calcium alloy both have strong toughness, they will have a serious cold welding phenomenon during the ball milling process, which makes it difficult to achieve effective ball milling and greatly reduces the powder production efficiency. Ineffective ball milling also further leads to difficulty in complete hydrogenation, thus reducing the theoretical hydrogen production amount.

[0004] Therefore, how to effectively solve the cold welding phenomenon of magnesium-based hydrolysis hydrogen production powder materials during the ball milling process and improve the powder production efficiency is one of the keys to solving the large-scale production and preparation of the materials and facing the engineering application as a portable hydrogen source. SUMMARY

[0005] The application aims to provide a preparation method of a cold-weld-free magnesium-based hydrolysis hydrogen production powder material to solve the technical problem that the existing magnesium-based hydrolysis hydrogen production powder material is prone to cold welding during the ball milling process.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A cold-weld-free magnesium-based hydrolysis hydrogen production powder material, which is composed of Mg x Ca 1-x alloy hydride and expanded graphite in a mass ratio of 80-95:5-20; the value range of x is 0.7-1.

[0008] Further, the phase of the Mg x Ca 1-x alloy hydride includes Ca4Mg3H 14and MgH2.

[0009] The technical solution also provides a preparation method of the cold-welding-free magnesium-based hydrolysis hydrogen production powder material.

[0010] S1: crushing Mg x Ca 1-x After the alloy is crushed, the expanded graphite is added, and then ball milling is performed to obtain Mg x Ca 1-x alloy-expanded graphite powder.

[0011] S2: repeatedly activating and hydrogenating the Mg x Ca 1-x alloy-expanded graphite powder to obtain Mg x Ca 1-x alloy hydride-expanded graphite composite material.

[0012] Further, in S1, the phase of the Mg x Ca 1-x alloy includes CaMg2 and Mg.

[0013] Further, in S1, the proportion of the Mg x Ca 1-x alloy is 95wt%-80wt%, and the proportion of the expanded graphite is 5wt%-20wt%.

[0014] Further, in S1, the ball-to-material ratio of the ball milling is 15:1-25:1, the diameter of the grinding ball is 3-20mm, the rotating speed is 1200-1800r / min, and the time is 2-5h.

[0015] Further, in S1, the particle size of the crushed Mg x Ca 1-x alloy is less than 200 mesh.

[0016] Further, in S2, the temperature of the repeated activation and hydrogenation is 350-450℃, and the time is 4-16h.

[0017] The technical solution also provides an application of the cold-welding-free magnesium-based hydrolysis hydrogen production powder material in hydrolysis hydrogen production.

[0018] Further, the cold-welding-free magnesium-based hydrolysis hydrogen production powder material is contacted with water or a salt solution to produce hydrogen; the solute of the salt solution is selected from at least one of aluminum chloride, sodium chloride, potassium chloride, calcium chloride and magnesium chloride.

[0019] The principle of the scheme is that:

[0020] The application provides a cold-welding-free magnesium-based hydrolysis hydrogen production powder material for hydrolysis hydrogen production, which contains the following components and in the following proportions: Mg xCa 1-x Hydrogenated alloy 95wt%-80wt%, wherein x represents the mass fraction of Mg, x ranges from 0.7 to 1; expanded graphite 5wt%-20wt%. The preparation method of the composite material is to mix Mg x Ca 1-x After the alloy is crushed, the expanded graphite is mixed and ball milled, and then activated and hydrogenated. The magnesium-based hydrolysis hydrogen powder material and the preparation method thereof for hydrolysis hydrogen provided by the application effectively inhibit the cold welding phenomenon of the material in the ball milling powder preparation process, improve the powder preparation efficiency, effectively reduce the particle size, promote hydrogenation, and thus improve the hydrolysis hydrogen production. The inventor analyzes the reason for inhibiting cold welding: in the ball milling process, the expanded graphite is distributed on the surface of the material as a dispersant, preventing the contact between Mg and CaMg2, thereby effectively inhibiting the occurrence of cold welding, greatly improving the powder preparation efficiency, and effectively reducing the particle size and improving the hydrogenation effect.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] (1) For magnesium-based alloys with strong toughness, cold welding occurs easily during the ball milling powder preparation process, thereby reducing the powder preparation efficiency. The Mg x Ca 1-x Hydrogenated alloy-expanded graphite composite material, due to the addition of expanded graphite, solves the above technical problems.

[0023] (2) The Mg x Ca 1-x Hydrogenated alloy-expanded graphite composite material has a particle size small enough to promote complete hydrogenation of the material, thereby improving the theoretical hydrolysis hydrogen production of the material.

[0024] (3) The hydrolysis hydrogen production of magnesium-based materials is usually limited by the Mg(OH)2 passivation layer generated on the surface of the material. The Mg x Ca 1-x Hydrogenated alloy-expanded graphite composite material, during the hydrolysis process, the graphite distributed on the surface of the material can effectively prevent the adhesion of Mg(OH)2 deposition, thereby delaying the formation of the passivation layer; the graphite partially embedded in the material body can also provide a channel for water to enter the interior of the particles, thereby improving the hydrolysis conversion rate.

[0025] (4) The application uses low-cost Mg x Ca 1-x Alloy and expanded graphite as raw materials, which effectively improves the preparation efficiency of the powder material and is conducive to realizing large-scale production of the material for industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a comparison chart of the cold welding inhibition effect of Example 1 of the application.

[0027] Figure 2 This is a comparison chart of XRD results for Embodiment 2 of the present invention.

[0028] Figure 3 This is a TEM image of Embodiment 2 of the present invention.

[0029] Figure 4 This is a comparison chart of the hydrogen production performance by hydrolysis in Example 2 of the present invention.

[0030] Figure 5 This is a microscopic image of the composite material in Comparative Example 3. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials, reagents, etc. used are all commercially available.

[0032] Example 1

[0033] Mg 0.7 Ca 0.3 Alloy (purchased from Suzhou Chuanmao Metal Materials Co., Ltd., a specific ratio of Mg) x Ca 1-x The alloy, as tested, contains Mg. x Ca 1-x The alloy phases (including CaMg2 and Mg) are crushed and ground to less than 200 mesh (i.e., the alloy is pulverized and passed through a 200-mesh sieve; as a preferred option, the alloy can be ground to less than 160 mesh), with no or 5 wt% expanded graphite (Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., 80 mesh; i.e., Mg) added. x Ca 1-x The mass ratio of alloy to expanded graphite was 95:5 (the calculation method for material usage in subsequent experiments is the same as here and will not be repeated). High-energy ball milling was performed for 2 hours under an argon atmosphere (at normal pressure) (ball-to-material ratio 20:1; in actual operation, a ball-to-material ratio of 15:1-25:1 can be used; the diameter of the grinding balls can be 3-20 mm; in this specific embodiment, 5 mm and 10 mm diameter grinding balls were used, with a mass ratio of 1:1; the rotation speed was 1500 rpm to obtain Mg). x Ca 1-x Alloy-expanded graphite powder.

[0034] This embodiment compares Mg 0.7 Ca 0.3 The effect of alloys with and without expanded graphite (5 wt% expanded graphite) on cold welding phenomenon after ball milling.

[0035] Figure 1 is a cold welding inhibition effect comparison chart, apparently, when no expanded graphite is added, serious cold welding occurs, and a large amount of material adheres to the bottom and side wall of the ball milling tank. After adding 5wt% expanded graphite, the cold welding phenomenon is effectively inhibited, and the material is in the form of dispersed particles and can be easily scraped off.

[0036] Example 2

[0037] This example is basically the same as Example 1, except that the amount of expanded graphite added is different, which is 20wt%, 12wt%, 5wt% expanded graphite and no expanded graphite. After ball milling is completed, the material obtained after ball milling is placed in a Sieverts reactor, and repeated activation (vacuum in the reactor, vacuum degree is 1Pa) and hydrogenation (hydrogen is added, and the hydrogen pressure in the reactor is maintained at 3-4MPa) at a temperature of 350℃. The process of repeated activation and hydrogenation is as follows: activation for 60min and hydrogenation for 60min, which is repeated for 4h. In addition, according to actual needs, the repeated activation-hydrogenation temperature can be 350-450℃, and the above activation-hydrogenation process can be continued for 4-16h, which can achieve ideal effect. Thus, Mg 0.7 Ca 0.3 alloy hydride-expanded graphite composite material. The Mg 0.7 Ca 0.3 alloy hydride-expanded graphite composite material contains Mg 0.7 Ca 0.3 alloy hydride and expanded graphite. In this technical solution, the Mg x Ca 1-x alloy hydride, x represents the mass fraction of Mg, and the value of x is 0.7-1. The Mg x Ca 1-x alloy hydride and expanded graphite have a mass ratio of 80-95:5-20, i.e. the Mg x Ca 1-x alloy hydride accounts for 95wt%-80wt%, and the expanded graphite accounts for 5wt%-20wt%, and the sum of the two is 100%.

[0038] This example compares the Mg 0.7 Ca 0.3The particle size and degree of hydrogenation of the alloy hydride-expanded graphite composite material were analyzed using a laser particle size analyzer. The median particle size was the largest (32.69 μm) without expanded graphite. After adding 5 wt%, 12 wt%, and 20 wt% expanded graphite, the median particle size decreased to 21.31 μm, 20.71 μm, and 16.87 μm, respectively, indicating that the addition of expanded graphite effectively reduced the Mg content. 0.7 Ca 0.3 Particle size of alloy hydride-expanded graphite composite material.

[0039] Mg was analyzed by XRD 0.7 Ca 0.3 The phase composition of the alloy hydride-expanded graphite composite material is as follows: Figure 2 As shown, Mg was detected only in the material without expanded graphite, while the other materials contained only Ca4Mg3H4O. 14 The material contains two phases, Mg and MgH2, therefore it can be considered that the smaller particle size resulting from the addition of expanded graphite is beneficial to the complete hydrogenation of the material. That is, the Mg synthesized using this technical method... x Ca 1-x The phases of the alloy hydride include only Ca4Mg3H 14 With MgH2, hydrogenation is complete.

[0040] Mg added at 20 wt% expanded graphite 0.7 Ca 0.3 The alloy hydride-expanded graphite composite material was characterized by TEM. The TEM characterization results are as follows: Figure 3 As shown, it can be clearly observed that the graphite coating on the material surface hinders the adhesion of Mg(OH)2 precipitate during hydrolysis, thus delaying the formation of the passivation layer. Furthermore, some graphite is embedded in the material body, providing channels for water to enter the particle interior and for hydrogen evolution. Therefore, the addition of expanded graphite can prevent the formation of a passivation layer on the surface of the powder material during hydrolysis to produce hydrogen, and the embedding of some graphite into the material body makes it easier for water to enter, thereby improving the hydrolysis conversion rate.

[0041] 0.1 g of the prepared composite material was placed in a reactor at a constant temperature of 25°C, and 10 mL of deionized water at 25°C was injected. The reaction was allowed to proceed for 20 min, and hydrogen gas was collected by water displacement. The resulting volume was converted to standard conditions. The results are as follows: Figure 4 As shown, the hydrogen production without the addition of expanded graphite is 715 mL / g. com The hydrogen production after adding 5 wt%, 12 wt%, and 20 wt% expanded graphite was 751 mL / g, respectively. com 825mL / g com and 733 mL / g com, which indicates that the addition of expanded graphite promotes the improvement of the hydrogen production performance to a certain extent. Among them, the addition of 12wt% of expanded graphite is the best for improving the hydrogen production performance of Mg 0.7 Ca 0.3 Hydride-alloy-expanded graphite composite material has the best effect on hydrogen production.

[0042] It can be seen that expanded graphite has multiple effects in the technical solution: the addition of expanded graphite not only prevents the occurrence of cold welding phenomenon, but also further reduces the particle size of the powder material and improves the hydrogenation rate of the alloy material, thereby improving the theoretical hydrogen production capacity of the material; it can also form a graphite coating on the surface of the material to avoid the formation of a passivation layer during the hydrolysis of the material, and some graphite is embedded in the material body, making it easier for water to enter the material body and improving the hydrolysis conversion rate. The initial purpose of introducing expanded graphite in the technical solution is to prevent the occurrence of cold welding phenomenon. During the actual research, the inventors accidentally discovered other effects of introducing expanded graphite, which was not expected before the actual research. In addition, expanded graphite also has a price advantage, which can greatly reduce the process cost. The inventors researched the prices of graphite additives, and the cost of multi-walled carbon nanotubes is 200-300 million yuan / ton, the cost of single-walled carbon nanotubes is 1200-1500 million yuan / ton, the cost of graphene is about 40 million yuan / ton, and the cost of expanded graphite is about 60 million yuan / ton. Therefore, the technical solution has a significant advantage in terms of cost.

[0043] Example 3

[0044] In this example, Mg 0.7 Ca 0.3 Hydride-alloy-expanded graphite composite material was prepared according to the method of Example 2, and the hydrogen production performance of hydrolysis in AlCl3 solution was studied.

[0045] 0.1g of the composite material was placed in a reactor with a constant temperature of 25℃, 10mL of 0.1mol / L, 0.2mol / L and 0.3mol / L AlCl3 solution with a temperature of 25℃ was injected, and the reaction was carried out for 5min. Hydrogen was collected by the drainage method, and the results were converted to the volume under standard conditions.

[0046] The results show that the hydrogen production of Mg 0.7 Ca 0.3 Hydride-alloy-expanded graphite composite material in 0.1mol / L, 0.2mol / L and 0.3mol / L AlCl3 solution is 1122mL / g com , 1201mL / g com and 1345mL / g com , respectively. Among them, the conversion rate in 0.3mol / L AlCl3 solution reaches 100%.

[0047] Example 4

[0048] This example does not use the alloy of calcium and magnesium to prepare the composite material, and the preparation process of the composite material is as described in Example 2, except that Mg 0.7 Ca 0.3 The alloy is replaced by Mg, and the addition of expanded graphite is as follows: 20wt% expanded graphite is added or no expanded graphite is added.

[0049] Take 0.1 g of the composite material and place it in a reactor at a constant temperature of 25°C, inject 10 mL of deionized water at a temperature of 25°C, and react for 20 min. Collect hydrogen gas by the drainage method, and convert the obtained results to the volume at standard conditions.

[0050] The results show that the hydrogen production without adding expanded graphite is 128 mL / g com, and the hydrogen production after adding 20wt% expanded graphite is increased to 261 mL / g com, indicating that the addition of expanded graphite promotes the improvement of the hydrogen production performance to a certain extent.

[0051] Comparative Example 1

[0052] This comparative example compares Mg 0.7 Ca 0.3 Hydrogen production performance of the alloy hydride changes at different ball milling speeds, and other operation steps are the same as in Example 2 (the addition amount of expanded graphite is 20wt%), except that the ball milling speed is set to 1500 rpm and 400 rpm, and Mg 0.7 Ca 0.3 Hydrogen production performance of the alloy hydride changes at different ball milling speeds, and other operation steps are the same as in Example 2 (the addition amount of expanded graphite is 20wt%), except that the ball milling speed is set to 1500 rpm and 400 rpm, and Mg

[0053] The results show that the hydrogen production is 715 mL / g com at a speed of 1500 rpm, and the hydrogen production is 641 mL / g com at a speed of 400 rpm, indicating that higher ball milling speed promotes the improvement of the hydrogen production performance of the material.

[0054] Comparative Example 2

[0055] This technical solution avoids the occurrence of cold welding during ball milling by adding expanded graphite during ball milling, and further improves the hydrogen production performance of the composite material. Expanded graphite is a carbon material, and in fact, adding carbon material to the alloy in the prior art cannot achieve the technical effect of this solution.

[0056] For example, in Chinese Patent CN114105094A, a (Mg 10 Ni) 85Ce 15 A magnesium-aluminum alloy hydrolysis hydrogen production material and method are synergistically modified with carbon nanotubes (CNT, a carbon material). The technology introduces (Mg 10 Ni) 85 Ce 15 A ternary high-activity alloy and carbon nanotubes (CNT) surface-modified industrial Mg-Al alloy residual waste are used to produce hydrogen at a high yield and at a high speed in simulated seawater. In the technology, the purpose of adding lightweight and large specific surface area carbon nanotubes is mainly to destroy the dense Mg(OH)2 colloid layer on the surface of the waste magnesium-aluminum alloy produced by the hydrolysis of the high-activity alloy (CNT are lightweight and have a large specific surface area by themselves, and can be embedded into the surface of the waste magnesium-aluminum alloy), to provide a fast mass transfer path for the molecules of the medium solution, and to improve the hydrogen production yield. The expanded graphite added in the invention can inhibit the agglomeration of the Mg x Ca 1-x Cold welding phenomenon during alloy ball milling, which can improve the powder preparation efficiency, is a process problem encountered during material preparation, and can effectively promote large-scale production. In addition, the addition of expanded graphite can also reduce the particle size of the composite material powder and promote hydrogenation. It can also form a graphite coating on the surface of the material (to avoid the generation of a passivation layer). However, Chinese Patent CN114105094A does not report the effect of carbon nanotubes on preventing cold welding, reducing material particle size, and forming a coating layer on the outer layer of the material. In addition, the present technical solution is subjected to hydrogenation treatment, and the addition of expanded graphite can reduce the particle size of the material to improve the hydrogenation effect. Chinese Patent CN114105094A does not involve the hydrogenation treatment process (repeated activation and hydrogenation at a certain temperature) after the preparation of the composite material, and does not focus on the effect of carbon materials on the hydrogenation of magnesium-based hydrolysis hydrogen production materials. Therefore, expanded graphite, as a different carbon material from carbon nanotubes, has unexpected technical effects on magnesium-based hydrolysis hydrogen production powder materials compared to other carbon materials.

[0057] More specifically, we can compare the following experimental data: Mg 0.7 Ca 0.3 The hydrogenated alloy-expanded graphite composite material is observed by TEM to prove that the expanded graphite is coated on the surface of the material as a dispersant. Figure 3 However, the final material prepared by adding CNT in Chinese Patent CN114105094A is observed to have carbon nanotubes embedded in the surface of the material, as shown in Figure 5 This figure is selected from the attached Figure 3 of Chinese Patent CN114105094A. Figure 5 In this figure, (c) is a Mg-Al alloy; (d) is a (Mg 10 Ni) 85 Ce 15And CNT ball milling, the composite material obtained. It can be observed that the CNTs in the composite material in (d) are embedded on the surface of the Mg-Al alloy, and do not form an outer coating layer as in the present solution. Therefore, although both expanded graphite and carbon nanotubes belong to carbon materials and are also compounded with magnesium-containing alloys by ball milling treatment, they exhibit completely different patterns in the microstructure of the final product.

[0058] For another example, Chinese patent CN115287490A reports a magnesium-based hydrolysis hydrogen production composite material and a preparation method thereof. The specific process is as follows: step one, preparing Mg-Ca-Ni ternary alloy by flux protection method; step two, mechanically crushing the obtained Mg-Ca-Ni ternary alloy to obtain Mg-Mg2Ca-Mg2Ni alloy particles; step three, short-time high-energy ball milling of MWCNTs (nanomulti-walled carbon nanotubes) and alloy particles to obtain refined Mg-Mg2Ca-Mg2Ni-MWCNTs composite powder; step four, placing the composite powder into a tabletting die and using a tablet press to press into a block or sheet material to obtain a porous magnesium-based hydrolysis hydrogen production composite material.

[0059] In patent CN115287490A, nanomulti-walled carbon nanotubes (MWCNTs) are also a carbon material, but there is a big difference in effect compared with the expanded graphite of the present solution. In this solution, porous sheet composite material is prepared by using the dispersibility of MWCNTs, and the purpose of adding MWCNTs is to take advantage of its dispersibility to ensure that the fine Mg-Mg2Ca-Mg2Ni alloy powder after tabletting maintains a rapid and continuous hydrolysis reaction, and it also does not pay attention to the cold welding problem in the ball milling preparation process. The person skilled in the art cannot know from this patent technology whether the carbon material has an inhibitory effect on the cold welding phenomenon. Patent CN115287490A also does not have a hydrogenation treatment process (repeated activation and hydrogenation at a certain temperature) for the prepared material, and it cannot be known from this technical material whether the carbon material can reduce the particle size of the composite material powder and thus promote hydrogenation.

[0060] Therefore, the addition of the expanded graphite material of the present technical solution has the following unexpected technical effects compared with patent CN115287490A: inhibiting the cold welding phenomenon during alloy ball milling, improving the powder preparation efficiency; reducing the particle size of the material, promoting hydrogenation; forming an outer coating layer of the material, delaying the formation of the passivation layer, thereby improving the hydrolysis conversion rate, etc.

[0061] The above-mentioned are only embodiments of the present application, and common technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that, for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A magnesium-based hydrolysis hydrogen production powder material without cold welding, characterized in that: From Mg x Ca 1-x Composed of alloy hydride and expanded graphite; x ranges from 0.7 to 1; Mg x Ca 1-x The phases of the alloy hydride include only Ca4Mg3H 14 It contains MgH2 and no Mg; It is prepared by the following method: S1: Mg x Ca 1-x The alloy was pulverized and passed through a 200-mesh sieve, then expanded graphite was added, and the mixture was ball-milled to obtain Mg. x Ca 1-x Alloy-expanded graphite powder; Mg x Ca 1-x The alloy's phases include CaMg2 and Mg; Mg x Ca 1-x The alloy accounts for 88 wt%; expanded graphite accounts for 12 wt%. The ball-to-material ratio of the ball mill is 15:1-25:1, the diameter of the grinding balls is 3-20mm, the rotation speed is 1200-1800 rpm, and the time is 2-5h. S2: For Mg x Ca 1-x The alloy-expanded graphite powder was repeatedly activated and hydrogenated to obtain Mg x Ca 1-x Alloy hydride-expanded graphite composite material.

2. The method for preparing a cold-welding-free magnesium-based hydrolysis hydrogen production powder material according to claim 1, characterized in that: The steps are as follows, performed sequentially: S1: Mg x Ca 1-x The alloy was pulverized and passed through a 200-mesh sieve, then expanded graphite was added, and the mixture was ball-milled to obtain Mg. x Ca 1-x Alloy-expanded graphite powder; Mg x Ca 1-x The alloy's phases include CaMg2 and Mg; Mg x Ca 1-x The alloy accounts for 88 wt%; expanded graphite accounts for 12 wt%. The ball-to-material ratio of the ball mill is 15:1-25:1, the diameter of the grinding balls is 3-20mm, the rotation speed is 1200-1800 rpm, and the time is 2-5h. S2: For Mg x Ca 1-x The alloy-expanded graphite powder was repeatedly activated and hydrogenated to obtain Mg x Ca 1-x Alloy hydride-expanded graphite composite material.

3. The method for preparing a cold-welding-free magnesium-based hydrolysis hydrogen production powder material according to claim 2, characterized in that: In S2, the temperature for repeated activation and hydrogenation is 350-450℃ and the time is 4-16h.

4. The application of the cold-welding-free magnesium-based hydrolysis hydrogen production powder material according to claim 1 in hydrolysis hydrogen production.

5. The application of the cold-welding-free magnesium-based hydrolysis hydrogen production powder material according to claim 4 in hydrolysis hydrogen production, characterized in that, Hydrogen is produced by contacting a non-cold-welding magnesium-based hydrolysis hydrogen-producing powder material with water or a salt solution; the solute in the salt solution is selected from at least one of aluminum chloride, sodium chloride, potassium chloride, calcium chloride, and magnesium chloride.

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