Method for producing magnesium-based hydride

Abstract

Provided is a method for efficiently producing one MgH2 (magnesium hydride) structure from one Mg compact made of a raw material mainly composed of magnesium. 【Solution means】In a state of a predetermined pressure range and a state of a predetermined temperature range in a hydrogen gas atmosphere, by reacting the components in the Mg compact with hydrogen gas, a step of producing a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined is carried out by accommodating the Mg compact in a reaction box that is sealed and has a function of maintaining the internal space pressure and the internal space temperature in a state of a predetermined pressure range and a state of a predetermined temperature range. A plurality of reaction boxes in which the step of producing the magnesium-based hydride is being executed are carried into a reaction station, and in the plurality of reaction boxes that have been carried in, the step of producing the magnesium-based hydride is executed while maintaining the internal space pressure and the internal space temperature in a state of a predetermined pressure range and a state of a predetermined temperature range.

Description

Technical Field

[0001] This invention relates to a method for producing a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined to generate hydrogen by reacting with water.

Background Art

[0002] MgH2 (magnesium hydride), which is a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined, is an ionic bond-type hydride composed of a bond between Mg 2+ and H - and is generated by reacting Mg (magnesium) with high-pressure hydrogen in a heated state. The reaction formula for generating MgH2 is Mg + H2 → MgH2.

[0003] Although the powder of MgH2 is charcoal gray and stable in air, it decomposes in water while reacting with water to release hydrogen. Therefore, MgH2 that has previously absorbed hydrogen can be used as a hydrogen storage material that releases hydrogen by reacting with water when necessary.

[0004] The reaction formula for MgH2 reacting with water is Pressure Temperature Water Supply MgO 0.5×10 3 hPa 440°C 0.30 kg / h 100% 1.0×10 3 hPa 470°C 0.27 kg / h 100% 2.0×10 3 hPa 600°C 0.25 kg / h 100% Under the conditions of MgH2 + H2O → MgO + 2H2 is represented.

[0005] Note that under normal temperature and pressure conditions, Mg(OH)2 is generated MgH2 + 2H2O → Mg(OH)2 + 2H2 It is also known that a hydrogen generation reaction as described above occurs.

[0006] As a by-product, MgO is more valuable, and the economy is good.

[0007] Regarding methods for producing magnesium-based hydrides, various proposals have been made in the past.

[0008] For example, Patent Document 1 proposes a method for producing a magnesium-based hydride by creating a compressed product in which a plurality of thin sheets having a thickness of 150 μm or less and containing magnesium as a main component are integrated and compressed, and reacting the components in the compressed product with hydrogen gas in a hydrogen gas atmosphere. By compressing the thin sheets containing Mg as the main component, strain is generated in the thin sheets, making it easier for Mg and hydrogen gas to react, and the yield of the magnesium-based hydride is said to be improved.

[0009] Also, Patent Document 2 proposes a method for producing magnesium hydride in which a unit containing a magnesium compressed body obtained by compression molding a thin sheet of magnesium is introduced into a first chamber connected to a first end of a cylindrical production furnace, the magnesium contained in the unit is heated in the first chamber, and while transporting the unit containing the heated magnesium compressed body from the first end to the second end of the production furnace, a magnesium hydride structure is generated, and the unit containing the generated magnesium hydride structure is cooled in a second chamber connected to the second end of the production furnace. It is said that the magnesium hydride production apparatus can be stably operated for a long time, and variations in the quality of the magnesium hydride structure can be prevented.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0011] This invention aims to propose a method for producing magnesium-based hydrides capable of efficiently producing one MgH₂ (magnesium hydride) structure from one Mg compressed body composed of a raw material mainly containing magnesium.

Means for Solving the Problems

[0012] The present invention for solving the above problems involves reacting the components in the Mg compressed body with hydrogen gas in a state of a predetermined pressure range and a predetermined temperature range in a hydrogen gas atmosphere, thereby combining a raw material mainly containing magnesium with hydrogen to produce a magnesium-based hydride. This is carried out by accommodating the Mg compressed body in a reaction box that is sealed and has a function of maintaining the internal space pressure and internal space temperature within the predetermined pressure range and the predetermined temperature range.

[0013] Also, a plurality of reaction boxes in each of which the process of producing magnesium-based hydrides is being executed are carried into each reaction station. In each of the carried-in plurality of reaction boxes, while maintaining the internal space pressure and internal space temperature within the predetermined pressure range and the predetermined temperature range, the process of producing magnesium-based hydrides is executed.

[0014] Furthermore, the reaction box in which the process of producing magnesium-based hydrides has been completed is taken out from the reaction station, and into the empty space of the reaction station from which the taking-out has been performed, a new reaction box containing an Mg compressed body and starting the process of producing magnesium-based hydrides is carried in, and the process of producing magnesium-based hydrides is advanced in the reaction box.

[0015] Such a present invention can be exemplified as follows. [1] A first step of producing fibrous magnesium fibers having a diameter of 10 nm to 1,000 nm and a length of at least 0.3 m or more by machining from an ingot mainly composed of magnesium in an inert gas atmosphere. A second step of accumulating the fibrous magnesium fibers produced in the first step in a mold and compressing them by cold isostatic pressing (CIP) to produce a magnesium bar having a cylindrical shape, a mirror surface shape in which the upper end edge circumference and the lower end edge circumference have R, and a specific gravity of 0.7 to 0.9 in an inert gas atmosphere. A third step of sawing the magnesium bar produced in the second step to produce a disc-shaped first magnesium disc in an inert gas atmosphere. A fourth step of pressing the first magnesium disc produced in the third step to produce a thin disc-shaped second magnesium disc having a specific gravity of 1.4 or more in an inert gas atmosphere. A fifth step of producing a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined by reacting the components in the second magnesium disc with hydrogen gas in a state of a predetermined pressure range and a predetermined temperature range in a hydrogen gas atmosphere. A method for producing a magnesium-based hydride comprising the above steps.

[0016] [2] The fifth step is performed in a reaction box in which the second magnesium disc is hermetically accommodated. The reaction box includes: An opening / closing means for closing the internal space of the reaction box and opening and closing the internal space when accommodating and carrying out the second magnesium disc into and out of the internal space; A temperature sensor for detecting the internal temperature of the sealed internal space; Temperature adjusting means including a heating and cooling mechanism for adjusting the temperature of the sealed internal space; A pressure sensor for detecting the internal pressure of the sealed internal space; An air supply valve mechanism used when gas is supplied from the outside to the sealed internal space, and an exhaust valve mechanism used when gas is exhausted from the sealed internal space to the outside are provided, The fifth step is, while exhausting the inert gas from the internal space of the reaction box in which the second magnesium disk is hermetically stored to the outside through the exhaust valve mechanism and supplying hydrogen into the internal space through the air supply valve mechanism, a hydrogen substitution step of replacing the sealed internal space with a hydrogen atmosphere; heating the internal space after the hydrogen substitution step by the temperature adjusting means to bring it to the predetermined temperature range state in the fifth step, and supplying hydrogen into the internal space through the air supply valve mechanism to bring the internal space to the predetermined pressure range state in the fifth step, a first temperature and pressure adjusting step; A method for producing a magnesium-based hydride according to [1], comprising these steps.

[0017] [3] The fifth step is, carrying the reaction box after the first temperature and pressure adjusting step is completed into the reaction station, after the reaction box is carried into the reaction station, constantly detecting the internal temperature and internal pressure in the reaction box with the temperature sensor and the pressure sensor, maintaining the internal temperature at the predetermined temperature range state by the temperature adjusting means, and supplying hydrogen into the internal space through the air supply valve mechanism to maintain the internal space at the predetermined pressure range state in the fifth step, a second temperature and pressure adjusting step A method for producing a magnesium-based hydride according to [2], including this step.

[0018] [4] A plurality of the reaction boxes can be carried into the reaction station, In the fifth step, the reaction boxes after the first temperature and pressure adjusting step are sequentially put into the reaction station. In each of the plurality of reaction boxes introduced into the reaction station, the second temperature and pressure adjustment step is performed. A method for producing a magnesium-based hydride according to [3].

[0019] [5] The fifth step is performed in a reaction box that hermetically houses the second magnesium disk. The reaction box seals the internal space thereof, and has an opening / closing means for opening and closing the internal space when accommodating and carrying out the second magnesium disk into and out of the internal space, a temperature sensor for detecting the internal temperature of the sealed internal space, temperature adjustment means comprising a heating and cooling mechanism for adjusting the temperature of the sealed internal space, a pressure sensor for detecting the internal pressure of the sealed internal space, an air supply valve mechanism used when gas is supplied from the outside to the sealed internal space, and an exhaust valve mechanism used when gas is exhausted from the sealed internal space to the outside. It is provided with The fifth step sequentially carries the reaction box in which the second magnesium disk is hermetically housed into a reaction station capable of carrying in a plurality of the reaction boxes, and in each of the plurality of reaction boxes carried into the reaction station, sequentially starts the hydrogen substitution step, the first temperature and pressure adjustment step, and the second temperature and pressure adjustment step. A method for producing a magnesium-based hydride according to [1].

[0020] [6] The fifth step is performed in a reaction box that hermetically houses the second magnesium disk. The reaction box Closing means for closing the internal space of the reaction box and opening and closing the internal space when accommodating and removing the second magnesium disk into and from the internal space, A temperature sensor for detecting the internal temperature of the sealed internal space, Temperature adjusting means comprising a heating and cooling mechanism for adjusting the temperature of the sealed internal space, A pressure sensor for detecting the internal pressure of the sealed internal space, An air supply valve mechanism used when gas is supplied from the outside to the sealed internal space, An exhaust valve mechanism used when gas is exhausted from the sealed internal space to the outside, and comprising, In the fifth step, after carrying the reaction box in which the second magnesium disk is hermetically accommodated into a reaction station capable of carrying a plurality of the reaction boxes, In each of the plurality of reaction boxes, the hydrogen substitution step, the first temperature and pressure adjustment step, and the second temperature and pressure adjustment step are sequentially started. The method for producing magnesium-based hydride according to [1].

[0021] [7] A take-out step of taking out the reaction box after completion of the fifth step from the reaction station, Detecting the internal temperature and internal pressure in the reaction box after the take-out step by the temperature sensor and the pressure sensor, lowering the internal temperature to the ambient temperature state around the reaction box by the temperature adjusting means, and exhausting the hydrogen to the outside through the exhaust valve mechanism, thereby reducing the internal space to the atmospheric pressure state around the reaction box. A third temperature and pressure adjustment step, An inert gas substitution step of exhausting hydrogen from the internal space to the outside through the exhaust valve mechanism and supplying an inert gas into the internal space through the air supply valve mechanism, thereby substituting the sealed internal space with an inert gas atmosphere, After exhausting the inert gas from the internal space after the inert gas replacement step to the outside through the exhaust valve mechanism and supplying air into the internal space through the intake valve mechanism, an air replacement step of replacing the sealed internal space with air; After the air replacement step, an unloading step of opening the reaction box by the opening / closing means and unloading the magnesium-based hydride from the reaction box to the outside; A method for producing a magnesium-based hydride according to any one of [4], [5], and [6], further comprising:

[0022] [8] A method for producing a magnesium-based hydride according to [2], further comprising a first inert gas recycling step of recovering and recycling the inert gas exhausted to the outside in the hydrogen replacement step.

[0023] [9] A method for producing a magnesium-based hydride according to [7], further comprising a second inert gas recycling step of recovering and recycling the inert gas exhausted to the outside in the air replacement step.

Advantages of the Invention

[0024] According to this invention, one MgH2 (magnesium hydride) structure can be efficiently produced from one Mg compact made of a raw material mainly composed of magnesium.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiment for Carrying out the Invention

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. <Step of Producing Mg Compact> In the method for producing a magnesium-based hydride of the present embodiment, an example of the step of producing an Mg compact to be used in the magnesium-based hydride production step will be described. For example, an Mg compact can be produced by performing the following first to fourth steps.

[0027] <First Step> Fibrous magnesium fibers having a diameter of 10 nm to 1,000 nm and a length of at least 0.3 m or more are produced from an ingot mainly composed of magnesium by machining in an inert gas atmosphere.

[0028] For example, as shown in the reference photograph of three in FIG. 1(a), an Mg ingot (for example, 8 kg / one, specific gravity: 1.74) is machined in an Ar gas atmosphere, and fibrous magnesium fibers having a diameter of 10 nm to 1,000 nm and a length of at least 0.3 m or more are produced in an Ar gas atmosphere. FIG. 1(b) shows an example of the fibrous magnesium fibers produced in the first step in a reference photograph.

[0029] <Second Step> The fibrous magnesium fibers produced in the first step are accumulated in a mold in an inert gas atmosphere and compressed by cold isostatic pressing (CIP) to produce a magnesium bar with a specific gravity of 0.7 to 0.9, which is cylindrical and has a mirror surface shape with the upper edge circumference and the lower edge circumference having an R, in an inert gas atmosphere. Fig. 1(c) is a reference photo showing a part of the magnesium bar (cylindrical with a diameter of 300 mm and a length of 1,000 mm) produced in the second step with some parts omitted.

[0030] The second step is the process of compressing the fibrous magnesium fibers accumulated in the mold by cold isostatic pressing (CIP) in an inert gas atmosphere (for example, in an Ar gas atmosphere).

[0031] Cold isostatic pressing (CIP) is a conventionally known method and is carried out using a conventionally known dry cold isostatic pressing device.

[0032] The above-mentioned dry cold isostatic pressing device generally has a forming container formed in a vertical cylindrical shape, an upper lid and a lower lid that respectively close the upper opening and the lower opening of the forming container, and a cylindrical forming rubber mold is provided around the inside of the forming container via a pressure rubber mold.

[0033] The upper lid has an inner and outer double structure with an upper punch provided inside the frame of a hollow upper lid frame. Similarly, the lower lid also has an inner and outer double structure with a lower punch provided inside the frame of a hollow lower lid frame. By fitting the upper punch into the upper opening of the forming rubber mold by a predetermined amount and fitting the lower punch into the lower opening of the forming rubber mold by a predetermined amount, a cylindrical forming chamber for the object to be processed surrounded by these upper punch, forming rubber mold, forming rubber mold, and lower punch is formed.

[0034] Cold isostatic pressing (CIP) is a method of pressure-forming the object to be processed through a rubber mold incorporated in a pressure vessel in advance. It can smoothly perform the filling, pressurization, and removal of the object to be processed, and is easy to automate and suitable for mass production.

[0035] The magnesium bar 30 (Fig. 2(a)) with a specific gravity of 0.7 to 0.9 produced by compression using the cold isostatic pressing method (CIP) in an inert gas atmosphere (for example, in an Ar gas atmosphere) using the above-described dry cold isostatic pressing apparatus is cylindrical as illustrated in Fig. 2(b), and the upper edge circumference 31 and the lower edge circumference 32 are formed in a mirror-like shape having an R.

[0036] That is, by performing compression processing by the cold isostatic pressing method (CIP) using the above-described dry cold isostatic pressing apparatus, as illustrated in Fig. 2(b), the upper surface 30a of the magnesium bar 30 after compression processing is formed in a mirror plate shape, and the upper edge circumference 31a is formed in a mirror plate shape having an R. Similarly, the lower surface 30 of the magnesium bar 30 after compression processing is formed in a mirror plate shape, and the lower edge circumference 32a is formed in a mirror plate shape having an R.

[0037] When the Mg compact to be subjected to the step of producing the magnesium-based hydride is produced by compression processing by a conventional pressing method that performs X-axis compression, Y-axis compression, and Z-axis compression, an octahedral Mg compact is obtained. In the eight corner portions and the eight ridge line portions of this octahedral Mg compact, the compression ratio becomes high. For this reason, the hydrogenation rate of these portions becomes high and approaches 100%, and a phenomenon occurs in which the hydrogenation rate decreases in the step of producing the magnesium-based hydride from the Mg compact described later.

[0038] Since the compression processing performed in the present embodiment is by the cold isostatic pressing method (CIP) using the above-described dry cold isostatic pressing apparatus, the magnesium bar 30 (Fig. 2(a)) with a specific gravity of 0.7 to 0.9 after compression processing is cylindrical as illustrated in Fig. 2(b), and the upper surface 30a and the lower surface 30b are formed in a mirror plate shape, and the upper edge circumference 31 and the lower edge circumference 32 are formed in a mirror plate shape having an R. Therefore, it is possible to suppress the occurrence of the above-described phenomenon that occurs in compression processing by a conventional pressing method that performs X-axis compression, Y-axis compression, and Z-axis compression.

[0039] <Third Step> The magnesium bar 30 (Fig. 2) produced in the second step is sawn in an inert gas atmosphere (for example, in an Ar gas atmosphere) to produce a disk-shaped first magnesium disk. As a result, the first magnesium disk (diameter: 300 mm) shown in the reference photo in Fig. 1(d) is obtained. For example, a cylindrical magnesium bar 30 (Fig. 2(a)) produced in the second step with a vertical length (the length between the upper surface 30a and the lower surface 30b of the cylindrical magnesium bar 30) of 1,000 mm is sawn to obtain first magnesium disks (diameter: 300 mm) (Fig. 1(d)) each with a thickness of 100 mm.

[0040] As will be described later, the Mg compact produced through the first to fourth steps is subjected to the magnesium-based hydride production process. At this time, it is desirable that the Mg compact is compression-molded to a specific gravity of 1.4 or more for obtaining a good hydrogenation rate in the short-time magnesium-based hydride production process.

[0041] However, it is not easy to produce an Mg compact compression-molded to a specific gravity of 1.4 or more all at once from the fibrous magnesium fibers produced in the first step. It is advantageous in terms of the efficiency of producing the Mg compact to produce a magnesium bar with a uniform specific gravity of 0.7 to 0.9 by compression molding using the cold isostatic pressing method in the second step described above, produce a first magnesium disk with a predetermined thickness from this by sawing in the third step, and then produce an Mg compact compression-molded to a specific gravity of 1.4 or more by compression molding in the fourth step described later.

[0042] The reason for setting the specific gravity of the magnesium bar produced by compression molding using the cold isostatic pressing method in the second step described above in the range of 0.7 to 0.9 is considered in view of producing a first magnesium disk with a predetermined thickness from the magnesium bar by sawing in the third step and then producing an Mg compact with a specific gravity of 1.4 or more by compression molding in the subsequent second step.

[0043] <Fourth Step> The first magnesium disk produced in the above-described third step is press-worked in an inert gas atmosphere (for example, in an Ar gas atmosphere) to produce a second magnesium disk that is thin and disk-shaped and has a specific gravity of 1.4 or more. As a result, the second magnesium disk (diameter 300 mm, thickness 25 mm) shown in the reference photograph in Fig. 1(e) is obtained.

[0044] This second magnesium disk (Fig. 1(e)) becomes the Mg compact to be used in the subsequent step of producing magnesium-based hydride.

[0045] This Mg compact is made from an ingot mainly composed of magnesium (specific gravity 1.74 g / cm 3 ) produced in the first step described above. By machining, fibrous magnesium fibers with a diameter of 10 nm to 1,000 nm and a length of at least 0.3 m or more are produced, and these are integrated in a mold and compression-machined.

[0046] Therefore, this second magnesium disk with a specific gravity of 1.4 or more is a porous structure, and the substantial surface area of the fibrous magnesium fibers produced from an ingot mainly composed of magnesium is large. In addition, as described above, by being compression-machined to a specific gravity of 1.4 or more, it will show a good hydrogenation rate in the short-time magnesium-based hydride production step.

[0047] In order to show a good hydrogenation rate in such a short-time magnesium-based hydride production step, it is desirable that the specific gravity of the Mg compact produced by the compression-machining in the fourth step, that is, the second magnesium disk, is at least 1.4 or more.

[0048] Note that the compression-machining in the fourth step can also be compression-machining by the cold isostatic pressing method (CIP) using the above-described dry cold isostatic pressing device instead of press-work.

[0049] However, by producing a magnesium bar that is cylindrical, with upper and lower surfaces formed in a platen shape, and with the upper and lower edge circumferences formed in a platen shape having an R, in the second step, as described above, at least in order to suppress the occurrence of phenomena that occur in compression processing by a conventional pressing method that performs X-axis compression, Y-axis compression, and Z-axis compression, it is desirable that the second step be compression processing by a cold isostatic pressing method (CIP) using a dry cold isostatic pressing device.

[0050] On the other hand, considering the equipment cost, the compression processing in the fourth step is advantageously a pressing process as described above.

[0051] As described above, in the method for producing a magnesium-based hydride of the present invention, from an ingot mainly composed of magnesium (for example, 8 kg per piece, specific gravity: 1.74), the step of producing an Mg compact (that is, the second magnesium disk described above) to be used in the magnesium-based hydride production step (in the above example, the first to fourth steps) is all performed in an inert gas atmosphere (for example, in an Ar gas atmosphere).

[0052] Note that the inert gas (for example, Ar gas) used for performing the above-described steps in an inert gas atmosphere (for example, in an Ar gas atmosphere) can be recovered, recycled, and reused after the completion of the above-described steps. Since the inert gas (for example, Ar gas) is rare and expensive, having such an inert gas recycling step is advantageous in terms of cost.

[0053] <Magnesium-based hydride production step (fifth step)> In the method for producing a magnesium-based hydride of the present embodiment, as described above, after producing an Mg compact, that is, the second magnesium disk, in a state of a predetermined pressure range and a predetermined temperature range in a hydrogen gas atmosphere, the components in the second magnesium disk (Mg compact) and hydrogen gas are reacted to produce a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined.

[0054] At this time, as is conventionally known, the predetermined pressure range in the hydrogen gas atmosphere is, for example, 6,000 hPa to 10,000 hPa, and the predetermined temperature range in the hydrogen gas atmosphere is, as is conventionally known, for example, 550°C to 590°C. In this embodiment, as this fifth step (magnesium-based hydride production step), various forms described below can be adopted.

[0055] <Reaction box used in the fifth step (magnesium-based hydride production step)> In this embodiment, the fifth step (magnesium-based hydride production step) is performed in a reaction box that hermetically houses the second magnesium disk (Mg compact) produced in the above-described first to fourth steps.

[0056] Here, an embodiment of this reaction box will be described with reference to FIGS. 3 and 4.

[0057] The reaction box 1 shown as an example in FIGS. 3 and 4 is, for example, made of austenitic stainless steel and has a rectangular parallelepiped shape composed of a front wall 5, a rear wall 6, an upper wall 2, a bottom wall 7, a left side wall 3, and a right side wall 4. An internal space 12 of the reaction box 1 that is enclosed and sealed by these wall surfaces is formed.

[0058] The reaction box 1 is provided with opening / closing means (not shown). By opening or closing the front wall 5 by this opening / closing means, the internal space 12 is opened and closed.

[0059] In the illustrated embodiment, the opening / closing means (not shown) seals the internal space 12 of the reaction box 1 by closing the front wall 5 (FIG. 3), and also allows the second magnesium disk produced in the above-described first to fourth steps to be accommodated and carried out into the internal space 12 by opening the front wall 5 (FIG. 4).

[0060] In the illustrated embodiment, in the internal space 12 of the reaction box 1, a plurality of support rods 13a, 13b, ···, 13i that are spaced apart by a predetermined interval in the left-right direction in FIG. 4(a) and extend from the back side to the front side of the drawing form an upper support shelf 13. Similarly, a plurality of support rods 14a, 14b, ···, 14i that are spaced apart by a predetermined interval in the left-right direction in FIG. 4(a) and extend from the back side to the front side of the drawing form a lower support shelf 14.

[0061] As shown in FIG. 4, with the front wall 5 opened by an opening / closing means (not shown) and the internal space 12 opened, the second magnesium disks (Mg compacts) 20a, 20b produced in the above-described first to fourth steps are placed on the support shelves 13, 14. Next, with the front wall 5 closed by the opening / closing means (not shown) and the internal space 12 closed (FIG. 3), a magnesium-based hydride production step (fifth step) for the second magnesium disks (Mg compacts) 20a, 20b is carried out. In this way, the step of hermetically accommodating the Mg compact (that is, the second magnesium disk described above) to be used in the magnesium-based hydride production step in the internal space 12 of the reaction box 1 can also be carried out in an inert gas atmosphere (for example, in an Ar gas atmosphere).

[0062] In the illustration, two second magnesium disks (Mg compacts) to be used in the magnesium-based hydride production step (fifth step) are accommodated in the internal space 12 of the reaction box 1, but it can be variously changed so that only one can be accommodated or three or more can be accommodated.

[0063] Also, the form in which the second magnesium disk (Mg compact) to be used in the magnesium-based hydride production step (fifth step) is arranged in the internal space 12 of the reaction box 1 can be variously changed.

[0064] The reaction box 1 is provided with a temperature sensor, a temperature adjustment means, a pressure sensor, an air supply valve mechanism, and an exhaust valve mechanism.

[0065] In the illustrated embodiment, a temperature control mechanism 8 that also serves as a temperature sensor, a pressure sensor 9, an air supply valve mechanism 10, and an exhaust valve mechanism 11 are provided in the reaction box 1.

[0066] The temperature control mechanism 8 includes an outer part 8a of the temperature control mechanism located outside the reaction box 1 and an inner part 8b of the temperature control mechanism located inside the reaction box 1, and serves as a temperature sensor for detecting the internal temperature of the sealed internal space 12 and as a temperature adjustment means including a heating and cooling mechanism for adjusting the temperature of the sealed internal space 12.

[0067] The pressure sensor 9 includes an outer part 9a of the pressure sensor located outside the reaction box 1 and an inner part 9b of the pressure sensor located inside the reaction box 1, and serves to detect the internal pressure of the sealed internal space 12.

[0068] The air supply valve mechanism 10 includes an outer part 10a of the air supply valve mechanism located outside the reaction box 1 and an inner part 10b of the air supply valve mechanism located inside the reaction box 1, and is used when gas is supplied from the outside to the sealed internal space 12.

[0069] The exhaust valve mechanism 11 includes an outer part 11a of the exhaust valve mechanism located outside the reaction box 1 and an inner part 11b of the exhaust valve mechanism located inside the reaction box 1, and is used when gas is exhausted from the sealed internal space 12 to the outside.

[0070] Although not shown in FIGS. 3 and 4, an air supply pipe for supplying a predetermined gas from outside the reaction box 1 is connected to the air supply valve mechanism 10, and an exhaust pipe for exhausting gas from inside the reaction box 1 to the outside is connected to the exhaust valve mechanism 11, respectively.

[0071] Although not shown in FIGS. 3 and 4, the temperature control mechanism 8, the pressure sensor 9, the air supply valve mechanism 10, and the exhaust valve mechanism 11 each communicate information with an external control device (not shown) via predetermined wiring or the like to monitor the temperature and pressure, and perform temperature adjustment of the sealed internal space 12 by heating or cooling via the temperature control mechanism 8, gas supply to the internal space 12 of the reaction box 1 via the air supply valve mechanism 10, exhaust from the internal space 12 of the reaction box 1 to the outside via the exhaust valve mechanism 11, and internal pressure adjustment by gas supply to the internal space 12 of the reaction box 1 via the air supply valve mechanism 10.

[0072] Hereinafter, some embodiments when the second magnesium disk (Mg compressed body) produced in the above-described first to fourth steps is hermetically housed in the above-described reaction box 1 in which one embodiment was described with reference to FIGS. 3 and 4, and the fifth step (magnesium-based hydride production step) is carried out will be described.

[0073] <First Embodiment of the Fifth Step (Magnesium-Based Hydride Production Step)> As described above, in an inert gas atmosphere (for example, in an Ar gas atmosphere), in the reaction box 1 in which the Mg compressed body (that is, the above-described second magnesium disk) to be subjected to the magnesium-based hydride production step is hermetically housed in the internal space 12 of the reaction box 1, the fifth step (magnesium-based hydride production step) proceeds as follows.

[0074] (Hydrogen Replacement Step) The inert gas (the above-described argon gas) is exhausted from the internal space 12 of the reaction box 1 to the outside via the exhaust valve mechanism 11, and hydrogen is supplied into the internal space 12 via the air supply valve mechanism 10 to replace the sealed internal space 12 with a hydrogen atmosphere (FIG. 5).

[0075] By performing, in an inert gas atmosphere (for example, in an Ar gas atmosphere), the step of hermetically accommodating a Mg compact (the second magnesium disk described above) to be subjected to the magnesium hydride production process in the internal space 12 of the reaction box 1, the inert gas (for example, Ar gas) present in the internal space 12 is exhausted from the internal space 12 to the outside, and hydrogen gas is supplied into the internal space 12 to replace the sealed internal space 12 of the reaction box 1 with a hydrogen atmosphere.

[0076] In addition, a configuration can be adopted that further includes a first inert gas recycling step of recovering and recycling the inert gas (the above-described argon gas) exhausted to the outside in this hydrogen replacement step.

[0077] The inert gas (for example, the above-described argon gas) recycled in the first inert gas recycling step can be used as the inert gas (Ar gas) when performing, in an inert gas atmosphere (for example, in an Ar gas atmosphere), the step of producing a Mg compact (the second magnesium disk described above) to be subjected to the magnesium hydride production process from an ingot mainly composed of magnesium (for example, 8 kg per piece, specific gravity: 1.74) described above, or the step of hermetically accommodating a Mg compact (the second magnesium disk described above) to be subjected to the magnesium hydride production process in the internal space 12 of the reaction box 1. Further, it can be used for the purpose of supplying it into the internal space 12 of the reaction box 1 in the inert gas replacement step described later.

[0078] Since argon gas is rare and expensive, the magnesium hydride production method having the first inert gas recycling step is advantageous in terms of cost.

[0079] (First temperature and pressure adjustment step) The internal space 12 after the hydrogen substitution step is heated by a temperature adjustment means (temperature control mechanism 8) to a predetermined temperature range (550°C to 590°C) in a hydrogen gas atmosphere required for the magnesium-based hydride production step, and hydrogen is supplied into the internal space 12 through the air supply valve mechanism 10 to bring the internal space 12 to a predetermined pressure range (6,000 hPa to 10,000 hPa) in a hydrogen gas atmosphere required for the magnesium-based hydride production step.

[0080] By this first temperature adjustment and pressure adjustment step, a step of reacting the components in the second magnesium disks (Mg compacts) 20a, 20b with hydrogen gas to produce a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined is started.

[0081] <Second Form of the Fifth Step (Magnesium-Based Hydride Production Step)> After the start of the "first temperature adjustment and pressure adjustment step" in the first form described above, the temperature and pressure of the internal space 12 of the reaction box 1 vary as the magnesium-based hydride production step progresses. Therefore, after the "first temperature adjustment and pressure adjustment step" in the first form described above is started, the reaction box 1 is carried into a predetermined reaction station, and until the magnesium-based hydride production step is completed, the temperature and pressure of the internal space 12 of the reaction box 1 are maintained within a predetermined temperature range (550°C to 590°C) and a predetermined pressure range (6,000 hPa to 10,000 hPa) in a hydrogen gas atmosphere required for the magnesium-based hydride production step.

[0082] That is, the reaction box 1 after the completion of the "first temperature adjustment and pressure adjustment step" in the first form described above is carried into the reaction station.

[0083] After thus carrying the reaction box into the reaction station, a second temperature adjustment and pressure adjustment step described below is performed.

[0084] In this second temperature and pressure adjustment process, the internal temperature and internal pressure inside the reaction box 1 are constantly detected by a temperature sensor (temperature adjustment mechanism 8) and a pressure sensor 9, and the internal temperature is maintained within a predetermined temperature range (550°C to 590°C) by the temperature adjustment means (temperature adjustment mechanism 8). At the same time, hydrogen is supplied into the internal space 12 through the air supply valve mechanism 10 to maintain the internal space 12 within a predetermined pressure range (6,000 hPa to 10,000 hPa).

[0085] After the "first temperature and pressure adjustment process" in the above-described first embodiment is completed, the reaction box 1 is carried into the reaction station, and as described above, when the second temperature and pressure adjustment process is carried out, a plurality of reaction boxes 1 can be carried into the reaction station. After the "first temperature and pressure adjustment process" in the above-described first embodiment is completed, the reaction boxes 1 are sequentially introduced into the reaction station, and the second temperature and pressure adjustment process can be carried out for each of the plurality of reaction boxes 1 introduced into the reaction station.

[0086] FIG. 7 illustrates an example of such an embodiment.

[0087] The reaction station 100 is equipped with a drive conveyor 101 for carrying and transporting a plurality of reaction boxes.

[0088] After the "first temperature and pressure adjustment process" in the above-described first embodiment is completed, the reaction box 1a is carried onto the drive conveyor 101 of the reaction station 100 as shown by the arrow 103.

[0089] The reaction box 1b in FIG. 7 is a reaction box after the "first temperature and pressure adjustment process" in the above-described first embodiment is completed, prior to the reaction box 1a. In the process of moving in the direction indicated by the arrow 102 in FIG. 7, the above-described second temperature and pressure adjustment process is in progress.

[0090] In this way, a plurality of reaction boxes 1 can be carried into the reaction station, and after the first temperature control and pressure control steps described above are completed, the reaction boxes 1h, 1g, 1f, 1e, 1d, 1c, 1b, 1a are sequentially loaded onto the drive conveyor 101 of the reaction station 100, and the second temperature control and pressure control steps described above are performed in each of the plurality of loaded reaction boxes 1h, 1g, 1f, 1e, 1d, 1c, 1b, 1a.

[0091] <Third form of the fifth step (magnesium-based hydride production step)> In this third form, similar to the above, the fifth step (magnesium-based hydride production step) is carried out in the reaction box 1 described above. However, the specific embodiment is different from the second embodiment described above and is as follows.

[0092] That is, a plurality of reaction boxes 1 that hermetically contain the second magnesium disks 20a, 20b are sequentially loaded onto the drive conveyor 101 of the reaction station 100 capable of loading a plurality of reaction boxes 1, and in each of the reaction boxes 1h, 1g, 1f, 1e, 1d, 1c, 1b, 1a loaded into the reaction station 100, the above-described hydrogen substitution step, first temperature control and pressure control step, and second temperature control and pressure control step are sequentially started.

[0093] <Step of unloading the magnesium-based hydride> As described above, the magnesium-based hydride can be unloaded from the reaction box 1 in which the fifth step (magnesium-based hydride production step) is completed in the internal space 12 of the reaction box 1 as follows.

[0094] (Taking-out step) The reaction box 1h in which the above-described fifth step (magnesium-based hydride production step) is completed is taken out from the drive conveyor 101 of the reaction station 100 as indicated by the arrow 104 (Fig. 7).

[0095] (Third temperature control and pressure control step) The internal temperature and internal pressure of the reaction box within 1 hour after the extraction process are detected by a temperature sensor (temperature control mechanism 8) and a pressure sensor 9. The internal temperature is lowered to the ambient temperature state around the reaction box 1h by the temperature adjustment means (temperature control mechanism 8), and the internal space 12 is depressurized to the ambient pressure state around the reaction box 1h by exhausting hydrogen to the outside through the exhaust valve mechanism 11.

[0096] (Inert gas replacement process) Hydrogen is exhausted from the internal space 12 to the outside through the exhaust valve mechanism 11, and the sealed internal space 12 is replaced with an inert gas atmosphere by supplying an inert gas (e.g., argon gas) into the internal space 12 through the supply valve mechanism 10 (Fig. 6(a)).

[0097] (Atmosphere replacement process) After the inert gas replacement process described above, the inert gas (argon gas) is exhausted from the internal space 12 to the outside through the exhaust valve mechanism 11, and the sealed internal space 12 is replaced with the atmosphere by supplying the atmosphere into the internal space 12 through the supply valve mechanism 10 (Fig. 6(b)).

[0098] In addition, a second inert gas recycling process for recovering and recycling the inert gas (argon gas described above) exhausted to the outside in this atmosphere replacement process can be further provided.

[0099] The inert gas recycled in the second inert gas recycling step (for example, the argon gas described above) is used as the inert gas (Ar gas) when performing steps such as the step of producing the Mg compacts (the second magnesium disks described above) to be supplied to the magnesium hydride production step from the ingots mainly composed of magnesium described above (for example, 8 kg per piece, specific gravity: 1.74), such as the steps (in the above example, the first to fourth steps), or the step of hermetically accommodating the Mg compacts (the second magnesium disks described above) to be supplied to the magnesium hydride production step in the internal space 12 of the reaction box 1 in an inert gas atmosphere (for example, in an Ar gas atmosphere). Further, in this inert gas replacement step, it can be used for the purpose of supplying it into the internal space 12 of the reaction box 1.

[0100] Since argon gas is rare and expensive, the magnesium hydride production method having the second inert gas recycling step is advantageous in terms of cost.

[0101] (Unloading step) After the above-described air replacement step, the reaction box 1h is opened by opening and closing means (not shown), and the magnesium hydride is unloaded from the reaction box 1h to the outside.

[0102] By doing so, one MgH2 (magnesium hydride) structure can be efficiently produced from one Mg compact made of a raw material mainly composed of magnesium.

[0103] As described above, the embodiments of the present invention have been described with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the technical scope grasped from the description of the claims.

[0104] For example, in the above, an embodiment was described in which a reaction station that houses a plurality of reaction boxes 1 in which the fifth step (magnesium-based hydride production step) proceeds in the internal space 12 is provided with a drive conveyor 101. In the internal space 12 of the reaction box 1 sequentially carried onto the drive conveyor 101, the fifth step (magnesium-based hydride production step) proceeds respectively. While being conveyed by the drive conveyor 101, the fifth step (magnesium-based hydride production step) is completed, and the completed reaction box 1 is taken out from the reaction station (drive conveyor 101). At the position that has become empty due to the removal of the reaction box 1, a new reaction box 1 was carried in.

[0105] Instead of such a form, a fixed (pit type) reaction station can also be used. It is a fixed (pit type) reaction station having a space part that houses a plurality of reaction boxes 1 in which the fifth step (magnesium-based hydride production step) proceeds in the internal space 12.

[0106] Also in this case, the reaction box 1 is sequentially carried into the space part of the fixed (pit type) reaction station, the fifth step (magnesium-based hydride production step) is respectively made to proceed in the internal space 12 of the reaction box 1, and the reaction box 1 for which the reaction has been completed is sequentially taken out from the space part of the fixed (pit type) reaction station according to the order of loading. At the position that has become empty due to the removal of the reaction box 1, a new reaction box 1 is carried in.

Claims

1. A first step of producing fibrous magnesium fibers having a diameter of 10 nm to 1,000 nm and a length of at least 0.3 m or more by machining from an ingot mainly composed of magnesium in an inert gas atmosphere, a second step of accumulating the fibrous magnesium fibers produced in the first step in a mold and compressing them by a cold isostatic pressing (CIP) method to produce a magnesium bar having a cylindrical shape, a mirror surface shape having an R at the upper edge circumference and the lower edge circumference, and a specific gravity of 0.7 to 0.9 in an inert gas atmosphere, a third step of sawing the magnesium bar produced in the second step to produce a disk-shaped first magnesium disk in an inert gas atmosphere, a fourth step of pressing the first magnesium disk produced in the third step to produce a thin disk-shaped second magnesium disk having a specific gravity of 1.4 or more in an inert gas atmosphere, a fifth step of producing a magnesium-based hydride in which a raw material mainly composed of magnesium and hydrogen are combined by reacting the components in the second magnesium disk with hydrogen gas in a predetermined pressure range state and a predetermined temperature range state in a hydrogen gas atmosphere, and a method for producing a magnesium-based hydride comprising the above steps.

2. The fifth step is performed in a reaction box that hermetically houses the second magnesium disk, The reaction box includes opening and closing means for closing the internal space of the reaction box and opening and closing the internal space when accommodating and removing the second magnesium disk into and from the internal space, a temperature sensor for detecting the internal temperature of the sealed internal space, temperature adjusting means comprising a heating and cooling mechanism for adjusting the temperature of the sealed internal space, a pressure sensor for detecting the internal pressure of the sealed internal space, a gas supply valve mechanism used when gas is supplied from the outside to the sealed internal space, an exhaust valve mechanism used when gas is exhausted from the sealed internal space to the outside, and is provided with, The fifth step is Exhausting an inert gas to the outside from the internal space of the reaction box in which the second magnesium disk is hermetically stored through the exhaust valve mechanism and supplying hydrogen into the internal space through the intake valve mechanism to replace the sealed internal space with a hydrogen atmosphere; a hydrogen replacement step A first temperature and pressure adjustment step of heating the internal space after the hydrogen replacement step by the temperature adjustment means to bring it to the predetermined temperature range state in the fifth step and supplying hydrogen into the internal space through the intake valve mechanism to bring the internal space to the predetermined pressure range state in the fifth step The magnesium-based hydride production method according to claim 1, comprising the above.

3. The fifth step is After the first temperature and pressure adjustment step is completed, carrying the reaction box into a reaction station After the reaction box is carried into the reaction station Continuously detecting the internal temperature and internal pressure in the reaction box with the temperature sensor and the pressure sensor, maintaining the internal temperature at the predetermined temperature range state by the temperature adjustment means, and supplying hydrogen into the internal space through the intake valve mechanism to maintain the internal space at the predetermined pressure range state in the fifth step; a second temperature and pressure adjustment step The magnesium-based hydride production method according to claim 2, including the above.

4. A plurality of the reaction boxes can be carried into the reaction station In the fifth step, after the first temperature and pressure adjustment step is completed, the reaction boxes are sequentially loaded into the reaction station The magnesium-based hydride production method according to claim 3, wherein the second temperature and pressure adjustment step is performed in each of the plurality of reaction boxes loaded into the reaction station

5. A take-out step of taking out the reaction box after the fifth step from the reaction station Detecting the internal temperature and internal pressure in the reaction box after the take-out step with the temperature sensor and the pressure sensor, reducing the internal temperature to the ambient atmospheric temperature state around the reaction box by the temperature adjustment means, and exhausting the hydrogen to the outside through the exhaust valve mechanism to depressurize the internal space to the ambient atmospheric pressure state around the reaction box; a third temperature and pressure adjustment step An inert gas substitution step of exhausting hydrogen from the internal space to the outside through the exhaust valve mechanism and supplying an inert gas into the internal space through the intake valve mechanism to replace the sealed internal space with an inert gas atmosphere; An air substitution step of exhausting the inert gas from the internal space after the inert gas substitution step to the outside through the exhaust valve mechanism and supplying air into the internal space through the intake valve mechanism to replace the sealed internal space with air; An unloading step of opening the reaction box by the opening / closing means and unloading the magnesium-based hydride from the reaction box to the outside after the air substitution step; The method for producing a magnesium-based hydride according to claim 4, further comprising the above steps.

6. The method for producing a magnesium-based hydride according to claim 2, further comprising a first inert gas recycling step of recovering and recycling the inert gas exhausted to the outside in the hydrogen substitution step.

7. The method for producing a magnesium-based hydride according to claim 5, further comprising a second inert gas recycling step of recovering and recycling the inert gas exhausted to the outside in the air substitution step.

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