Hydrogen production agent and method for producing the same

Abstract

The present application provides a hydrogen production agent and a preparation method thereof. In one embodiment, the hydrogen production agent includes a first form before hydrogenation and a second form after hydrogenation, characterized in that: the first form includes magnesium powder and an alloy phase inlaid on the surface of the magnesium powder; a) the particle size of the magnesium powder ranges from 1 to 150 microns; b) the alloy phase is Al 12 Mg 17 ; and the second form includes magnesium hydride and aluminum.

Description

A hydrogen generating agent and preparation method thereof Technical Field

[0001] The invention relates to a hydrogen generating agent and a preparation method thereof. Background Art

[0002] Magnesium hydride can react with water to produce a large amount of hydrogen and is an efficient hydrogen-generating agent that is convenient for outdoor use. However, due to the active chemical properties of magnesium, it easily forms an oxide film in the air, which makes the synthesis of magnesium hydride difficult, with complex process conditions, long synthesis time, and high energy consumption. Therefore, magnesium hydride is expensive and has poor economic efficiency as a hydrogen-generating agent. The present invention adds a small amount of other elements, such as aluminum and sodium, to magnesium powder, controls the temperature so that magnesium and other elements first undergo an alloying reaction to form intermetallic hydrides, thereby destroying the surface oxide layer, and then carries out the hydrogenation reaction. This can simplify the magnesium hydrogenation production process, shorten the hydrogenation time, and reduce production energy consumption. Aluminum itself is also a hydrolysis hydrogen-generating agent, and its hydrogen production capacity is slightly smaller than that of magnesium hydride. Therefore, adding a small amount of aluminum will not have a significant impact on the hydrogen production capacity of magnesium hydride.

[0003] Summary of the Invention

[0004] The present invention provides a hydrogen-generating agent. In one embodiment, the hydrogen-generating agent includes a first form before the hydrogenation reaction and a second form after the hydrogenation reaction, characterized in that: the first form includes magnesium powder and an alloy phase embedded on the surface of the magnesium powder: a) the particle size of the magnesium powder is in the range of 1-150 microns; b) the alloy phase is Al 12 Mg 17 ; The second form includes magnesium hydride and aluminum.

[0005] The present invention further provides a method for hydrogenating the hydrogen-generating agent of the present invention from a first form to a second form. In one embodiment, the method comprises the following steps: a) placing the hydrogen-generating agent in the first form in a 1-10 MPa hydrogen environment; b) maintaining the temperature at 300-400°C for a hydrogenation reaction for 2-8 hours.

[0006] The present invention also provides a method for producing the first form of the hydrogen-generating agent described herein. In one embodiment, the method comprises the following steps: a) mixing magnesium powder having a uniform particle size of 1-150 microns with aluminum powder having a smaller particle size than the magnesium powder, with the magnesium-aluminum mixed atomic ratio being 95:5 to 75:25; and b) heating the magnesium-aluminum mixed powder from step (a) to 350-450°C in a 1-10 MPa hydrogen atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1 shows the preparation process flow of the present invention.

[0008] Figure 2 shows the mosaic structure formed by grinding magnesium powder and aluminum powder.

[0009] Figure 3 shows the magnesium-aluminum phase diagram.

[0010] Figure 4 shows the XRD pattern of the product without adding aluminum powder, and the degree of hydrogenation of pure magnesium is very low.

[0011] FIG5 shows the XRD pattern of the product when 10 at % aluminum powder is added. The magnesium in the sample has been substantially hydrogenated to form magnesium hydride.

[0012] FIG6 shows the XRD pattern of the product when 20 at % aluminum powder is added. The magnesium in the sample has been basically hydrogenated to form magnesium hydride. DETAILED DESCRIPTION

[0013] The present invention provides a magnesium hydride composite hydrogen-generating agent and a preparation method thereof. In this method, magnesium and an added second component such as sodium, aluminum, etc. undergo an alloying reaction at a specific temperature to destroy the surface oxide layer of the magnesium particles, provide a hydrogen diffusion channel, and then the hydrogen enters the interior of the magnesium particles to undergo a hydrogenation reaction. Taking aluminum as an example, magnesium powder and aluminum powder are mixed in a certain proportion, stirred, and ground, and the mixed powder is heated to 350-450°C under a hydrogen pressure of 1-10 MPa. During this process, magnesium and aluminum undergo an alloying reaction to generate Al 12 Mg 17 , the magnesium oxide on the surface of magnesium and aluminum is destroyed, exposing the fresh surface, and then maintaining the temperature at 300-400℃ for 2-8 hours, Al 12 Mg 17 Magnesium reacts with hydrogen to form magnesium hydride and aluminum. The magnesium reacts with hydrogen to form magnesium hydride, completing the preparation of the magnesium-based hydrogen-generating agent of the present invention, which is a mixture of magnesium hydride and aluminum. Aluminum itself is also a hydrogen-generating agent, but its hydrogen production capacity is slightly smaller than that of magnesium hydride. Therefore, adding a small amount of aluminum will not significantly affect the hydrogen production capacity of magnesium hydride. However, it can significantly simplify the magnesium hydrogenation process, shorten the hydrogenation time, and reduce energy consumption.

[0014] The advantages of the present invention are that by adding a small amount of other elements to magnesium powder, intermetallic hydrides are generated under specific process conditions, thereby destroying the oxide layer on the surface of the particles, thereby simplifying the magnesium hydrogenation production process, shortening the hydrogenation time, and reducing production energy consumption.

[0015] The present invention provides a hydrogen-generating agent. In one embodiment, the hydrogen-generating agent includes a first form before the hydrogenation reaction and a second form after the hydrogenation reaction, characterized in that: the first form includes magnesium powder and an alloy phase embedded on the surface of the magnesium powder: a) the particle size of the magnesium powder is in the range of 1-150 microns; b) the alloy phase is Al 12 Mg 17 ; The second form includes magnesium hydride and aluminum.

[0016] In one embodiment, the magnesium powder has a particle size range of 20-100 microns.

[0017] In one embodiment, the aluminum powder has a particle size range of 1-20 microns.

[0018] In one embodiment, the aluminum powder has a particle size range of 1-10 microns.

[0019] In one embodiment, the mixed magnesium-aluminum atomic ratio is 95:5-75:25.

[0020] In one embodiment, the mixed magnesium-aluminum atomic ratio is 90:10-80:20.

[0021] In one embodiment, the heating comprises raising the temperature to 350-450°C.

[0022] In one embodiment, the heating comprises raising the temperature to 395-450°C.

[0023] In one embodiment, the heating is performed in a 1-10 MPa hydrogen environment.

[0024] In one embodiment, the heating is performed in a 1.5-3 MPa hydrogen environment.

[0025] In one embodiment, the mosaic structure is formed by mixing and grinding the magnesium powder and the aluminum powder.

[0026] The present invention also provides a method for producing the first form of the hydrogen-generating agent described herein. In one embodiment, the method comprises the following steps: a) mixing magnesium powder having a uniform particle size of 1-150 microns with aluminum powder having a smaller particle size than the magnesium powder, with the magnesium-aluminum mixed atomic ratio being 95:5 to 75:25; and b) heating the magnesium-aluminum mixed powder from step (a) to 350-450°C in a 1-10 MPa hydrogen atmosphere.

[0027] In one embodiment, the hydrogen environment of step (a) is 1.5-3 MPa.

[0028] In one embodiment, the hydrogenation reaction in step (b) is 3-5 hours.

[0029] In one embodiment, the alloy phase is generated by uniformly mixing the magnesium powder and aluminum powder having a smaller particle size than the magnesium powder to form a mosaic structure and then heating.

[0030] The present invention further provides a method for hydrogenating the hydrogen-generating agent of the present invention from a first form to a second form. In one embodiment, the method comprises the following steps: 1) placing the hydrogen-generating agent in the first form in a 1-10 MPa hydrogen environment; and 2) maintaining the temperature at 300-400°C for a hydrogenation reaction for 2-8 hours.

[0031] In one embodiment, the step (1) further comprises stirring and grinding the magnesium powder and the aluminum powder into a mosaic structure.

[0032] Example 1

[0033] The preparation process is shown in Figure 1.

[0034] Magnesium powder and aluminum powder are weighed separately and then mixed. The magnesium powder has a particle size range of 1-150 microns, preferably 20-100 microns. The aluminum powder has a particle size range of 1-20 microns, preferably 1-10 microns. The aluminum powder has a smaller particle size than the magnesium powder. The magnesium-aluminum atomic ratio is 95:5 to 75:25, preferably 90:10 to 80:20.

[0035] After the magnesium powder and aluminum powder are mixed, they are stirred and ground until they are evenly mixed. Some of the magnesium powder and aluminum powder can form a mosaic structure after grinding (Figure 2), and the smaller aluminum powder is tightly adhered to the larger magnesium particles.

[0036] The mixed powder after mixing and grinding is placed in a sealed pressure-resistant container, and the container is filled with 1-10MPa hydrogen (preferably 1.5-3MPa). The mixed powder in the container is heated to 350-450℃, preferably 395-450℃. During the heating process, the tightly bound magnesium and aluminum react to form Al 12 Mg 17 Alloy phase. The formation of this alloy phase effectively breaks the surface oxide layer of the magnesium particles, making it easier for hydrogen to enter the interior of the particles during the subsequent hydrogenation process to undergo a hydrogenation reaction. The alloying temperature is preferably 395-450°C because: if the temperature is too low, the alloy phase generation rate is slow, and it takes a period of time to completely generate the alloy phase. If the temperature exceeds 450°C, the alloy phase may produce a molten phase (see Figure 3 for details), which is not conducive to the hydrogenation reaction. In the range of 395-450°C, magnesium and aluminum can quickly generate alloy phases and will not melt. 17Mg+12Al→Al 12 Mg 17

[0037] After alloying is completed, the temperature in the container is maintained at 300-400°C, the hydrogen pressure remains unchanged, and the temperature is kept for 2-8 hours, preferably 3-5 hours, to carry out the hydrogenation reaction. 12 Mg 17 Reacting with hydrogen to generate magnesium hydride and aluminum, magnesium reacts with hydrogen to generate magnesium hydride, and the magnesium-based hydrogen generating agent of the present invention is thus prepared, which is a mixture of magnesium hydride and aluminum and can be used as a material for hydrolysis hydrogen production. 12 Mg 17 +17H2→17MgH2+12Al Mg+H2→MgH2

[0038] Example 2

[0039] Pure magnesium powder with a particle size of 45 μm was heated to 450°C under a hydrogen pressure of 3 MPa, then cooled to 340°C and kept at this temperature for 5 hours. The XRD pattern of the product is shown in Figure 4. This shows that the degree of hydrogenation of pure magnesium is very low without the addition of aluminum powder.

[0040] Figure 5 shows the XRD pattern of a sample prepared by mixing 45-micron magnesium powder and 1-3-micron aluminum powder in a 90:10 atomic ratio. The mixture was heated to 420°C under a hydrogen pressure of 3 MPa, then cooled to 340°C and held for 5 hours. This indicates that with the addition of 10 at% aluminum powder, virtually all the magnesium in the sample has been hydrogenated to form magnesium hydride.

[0041] Example 3

[0042] Figure 6 shows the XRD pattern of a sample prepared by mixing 45-micron magnesium powder and 1-3-micron aluminum powder in an atomic ratio of 80:20. The mixture was heated to 420°C under a hydrogen pressure of 2 MPa, then cooled to 340°C and held for 3 hours. This indicates that with the addition of 20 at% aluminum powder, virtually all the magnesium in the sample has been hydrogenated to form magnesium hydride.

Claims

1. A hydrogen production agent, which includes a first form before the hydrogenation reaction and a second form after the hydrogenation reaction. Characterized in that: The first form includes magnesium powder and an alloy phase embedded on the surface of the magnesium powder: a. The particle size range of the magnesium powder is 1 - 150 microns; b. The alloy phase is Al 12 Mg 17 ; The second form includes magnesium hydride and aluminum.

2. The hydrogen production agent according to claim 1, Characterized in that: The alloy phase is formed by uniformly mixing the magnesium powder with aluminum powder having a particle size smaller than that of the magnesium powder, forming an embedded structure, and then heating.

3. The hydrogen production agent according to claim 1, Characterized in that: The particle size range of the magnesium powder is 20 - 100 microns.

4. The hydrogen production agent according to claim 1, Characterized in that: The particle size range of the aluminum powder is 1 - 20 microns.

5. The hydrogen production agent according to claim 4, Characterized in that: The particle size range of the aluminum powder is 1 - 10 microns.

6. The hydrogen production agent according to claim 2, Characterized in that: The atomic ratio of magnesium to aluminum in the mixture is 95:5 - 75:

25.

7. The hydrogen production agent according to claim 6, Characterized in that: The atomic ratio of magnesium to aluminum in the mixture is 90:10 - 80:

20.

8. The hydrogen production agent according to claim 2, Characterized in that: The heating includes raising the temperature to 350 - 450 °C.

9. The hydrogen production agent according to claim 8, Characterized in that: The heating includes raising the temperature to 395 - 450 °C.

10. The hydrogen production agent according to claim 2, Characterized in that: The heating is carried out in a hydrogen environment of 1 - 10 MPa.

11. The hydrogen production agent according to claim 10, Characterized in that: The heating is carried out in a hydrogen environment of 1.5 - 3 MPa.

12. The hydrogen production agent according to claim 2, Characterized in that: The embedded structure is formed by stirring and grinding the magnesium powder and the aluminum powder.

13. A method for hydrogenating the hydrogen production agent according to claim 1 from the first form to the second form, Characterized in that It includes the following steps: a. Placing the hydrogen production agent in the first form in a hydrogen environment of 1 - 10 MPa; b. Maintaining the temperature at 300 - 400 °C for 2 - 8 hours for the hydrogenation reaction.

14. The method according to claim 13, Characterized in that: The hydrogen environment in step (a) is 1.5 - 3 MPa.

15. The method according to claim 13, Characterized in that: The hydrogenation reaction in step (b) is 3 - 5 hours.

16. A method for producing the hydrogen production agent in the first form according to claim 1, Characterized in that It includes the following steps: a. Uniformly mixing magnesium powder with a particle size of 1 - 150 microns with aluminum powder having a particle size smaller than that of the magnesium powder, and the atomic ratio of magnesium to aluminum in the mixture is 95:5 - 75:25; b. Heating the magnesium-aluminum mixed powder in step (a) to 350 - 450 °C in a hydrogen environment of 1 - 10 MPa.

17. The method according to claim 16, Characterized in that: Step (a) further includes stirring and grinding the magnesium powder and the aluminum powder into an embedded structure.

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