JP7207685B2 - Hydrogen storage material, method for producing hydrogen storage material, and method for producing hydrogen storage alloy - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act ・Publication name: “The 4th Japan Institute of Metals and Materials Next-Generation Academic and Application Development Research Meeting on Hydrides” Publication date: November 16, 2017 ・Study meeting name: No. 4th Japan Institute of Metals, Japan Institute of Metals and Materials Next-Generation Academic and Application Development Study Group on Hydride Venue Okinawa Industry Support Center Middle Hall Date November 16, 2017

TECHNICAL FIELD The present invention relates to a hydrogen storage material and the like that can realize cost reduction.

Hydrogen is a secondary energy that can be produced in various ways from a variety of primary energy sources. An energy system using hydrogen is expected to be put into practical use (commercialization) in the future because it can be expected to have effects such as high energy efficiency and low environmental load.

The energy density per volume of hydrogen is as low as about one-third that of natural gas. Therefore, when transporting and storing hydrogen, it is required to increase the density of hydrogen. A hydrogen storage alloy can store hydrogen atoms in the alloy by dissociating hydrogen molecules on the surface of the alloy. For example, Patent Documents 1 to 3 describe hydrogen storage alloys such as LaNi ₅ , TiFe and SrAl ₂ . In addition, Non-Patent Document 1 describes a hydride of Al ₂ Cu.

Japanese Patent Application Laid-Open No. 51-13934 (published on February 3, 1976) U.S. Pat. No. 3,922,872 (published Dec. 2, 1975) Japanese Patent Application Laid-Open No. 2001-262266 (published on September 26, 2001)

H. Saitoh et. al., APL Materials 1, 032113 (2013)

However, while the hydrogen storage alloys described in Patent Documents 1 to 3 are excellent in hydrogen absorption/desorption characteristics, they contain rare metals such as titanium and rare earth elements, so they have cost issues. Al ₂ Cu described in Non-Patent Document 1 uses only a base metal (general-purpose metal). Base metals are metals with large reserves, production volumes, and usage volumes, and include iron, copper, zinc, tin, aluminum, and the like. However, hydrides of Al ₂ Cu are stable only under high pressure, and their hydrogen storage capacity is relatively small at about 1% by mass. Therefore, it is difficult to use it as a hydrogen storage material.

In view of the current situation, one aspect of the present invention is a hydrogen storage material that can realize cost reduction while having hydrogen storage characteristics (high gravimetric hydrogen density) equivalent to those of conventionally known hydrogen storage alloys. An object of the present invention is to provide a method for producing a hydrogen hydride storage material and a method for producing a hydrogen storage alloy.

In order to solve the above-mentioned problems, the present inventors have made intensive studies, and as a result, have found that a specific alloy composed of a base metal that is difficult to hydrogenate has hydrogen storage properties, and have completed the present invention. We have also found that certain alloys of base metals and common metals (relatively cheap, high reserve metals) that are difficult to hydrogenate have hydrogen storage properties. That is, the present invention includes the following inventions. Conventional hydrogen storage alloys are generally produced by combining metals that are easily hydrogenated and metals that are difficult to hydrogenate. A hydrogen storage alloy can be manufactured at low cost.

[1] A hydrogen storage material characterized by containing one or more of alloys represented by the following compositional formulas (1) and (2) (provided that inevitable impurities are allowed to be contained):
AlxFe _{(1-x) (} 1)
Al _y Mn _(1-y) (2)
(Here, x is 0.70 or more and 0.80 or less, and y is 0.60 or more and 0.70 or less).

[2] Contains one or more of a first alloy containing aluminum and iron and a second alloy containing aluminum and manganese, wherein the first alloy is a crystal having an Al ₁₃ Fe ₄ type crystal structure and a crystal phase having an Al _2.8 Fe type crystal structure, and the second alloy is Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ A hydrogen storage material characterized by having a crystal phase having an Al ₁₂ type crystal structure.

[3] A hydrogen hydride storage material, characterized in that the hydrogen storage material according to [1] or [2] stores hydrogen therein.

[4] A method for producing a hydrogen storage material, comprising the step of causing the hydrogen storage material according to [1] or [2] to absorb hydrogen under pressure and heating conditions.

[5] A step of pressurizing and heating, in a hydrogen atmosphere, a mixed powder obtained by mixing powders of different types of difficult-to-hydrogenate metals at a compositional ratio that provides an alloy having hydrogen storage properties when alloyed. A method for producing a hydrogen storage alloy, comprising:

According to one aspect of the present invention, it can be manufactured using aluminum and any one of iron and manganese as main raw materials, and has the same hydrogen storage characteristics (high gravimetric hydrogen density) as conventionally known hydrogen storage alloys. A hydrogen storage material can be provided. Therefore, one embodiment of the present invention has an effect of realizing cost reduction in the hydrogen storage technology.

FIG. 3 is a diagram showing an example of the result of observing the hydrogenation reaction process of the hydrogen storage material in Embodiment 1 of the present invention using synchrotron radiation X-rays. (a) is a diagram showing an example of an X-ray diffraction pattern obtained by powder X-ray diffraction measurement using synchrotron radiation X-rays for the alloy hydride in Embodiment 1 of the present invention; is a table showing diffraction peaks in the X-ray diffraction pattern. FIG. 2 is a diagram showing the hydrogen release temperature at normal pressure of the hydrogen storage alloy after hydrogen storage in Embodiment 1 of the present invention. (a) is a diagram showing an example of an X-ray diffraction pattern obtained by powder X-ray diffraction measurement using synchrotron radiation X-rays for the hydrogen storage material according to Embodiment 2 of the present invention; [ Fig. 2] Fig. 2 is a diagram showing an example of the result of observing the hydrogenation reaction process of the hydrogen storage material using synchrotron radiation X-rays. FIG. 4 is a diagram showing an example of an X-ray diffraction pattern obtained by powder X-ray diffraction measurement using synchrotron radiation X-rays for the alloy hydride in Embodiment 2 of the present invention, and (b) is the X-ray 4 is a table showing diffraction peaks in a diffraction pattern; FIG. 5 is a graph showing the hydrogen release temperature at normal pressure of the hydrogen storage alloy after hydrogen storage in Embodiment 2 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The following description is for better understanding of the gist of the invention, and does not limit the invention unless otherwise specified. In addition, unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)".

In the following description, the findings of the present invention will be briefly described before describing the hydrogen storage material and the like in the embodiments of the present invention.

(Brief description of the findings of the invention)
In general, a hydrogen storage alloy is an intermetallic compound composed of a combination of a metal element that easily reacts with hydrogen (easily hydrogenated) and a metal element that does not easily react with hydrogen (hardly hydrogenates). Development guidelines for hydrogen storage alloys based on combinations of metal elements are known. In addition, the metal element which hardly reacts with hydrogen refers to a metal element which exhibits the following properties under the conditions of a pressure of 10,000 atmospheres or less and room temperature. That is, the Gibbs energy of a metal hydride in which the element ratio (H/M) of hydrogen (H) and metal (M) is greater than 0.5 It refers to a metallic element whose Gibbs energy is always relatively small.

Hydrogen storage alloys containing base metals as part of the elements constituting the alloy have been reported so far (for example, TiFe and SrAl ₂ described in Patent Documents 2 and 3). Since base metals are categorized as metal elements that are difficult to react with hydrogen (hereinafter sometimes referred to as difficult-to-hydrogenate metals), it has been conventionally considered impossible to create a hydrogen-absorbing alloy formed only from base metals. rice field.

In recent years, it has been reported that an alloy of aluminum and copper (Al ₂ Cu), which is a base metal, forms a hydride under conditions of 100,000 atmospheres and 800° C. (see Non-Patent Document 1). However, as described above, this hydride is stable only under high pressure and does not have a sufficient hydrogen storage capacity, and thus has insufficient performance as a hydrogen storage material. In addition, Non-Patent Document _{1 describes the mechanism of the hydrogenation reaction of Al 2 Cu} . Various atomic motions upon release of the torsion are described as effecting the hydrogenation reaction.

Therefore, based on the above mechanism, a guideline for searching for a hydrogen storage alloy formed only from a base metal can be considered. In this case, it is common to search for hydrogen storage alloys among alloys formed only from base metals and having an Al ₂ Cu type structure. However, after the report by Non-Patent Document 1, there has been no report on a hydrogen storage alloy having such a structure, and there is also no report on a hydrogen storage alloy formed only from a base metal. Therefore, those skilled in the art normally thought that it would be difficult to use, as a hydrogen storage alloy, an intermetallic compound composed only of a base metal that is classified as a difficult-to-hydrogenate metal.

Under such circumstances, the present inventors have investigated in detail the hydrogenation reactions of various intermetallic compounds composed of base metals and difficult-to-hydrogenate metals in order to develop materials from a new viewpoint. Specifically, the hydrogenation reaction of the intermetallic compound was repeatedly observed in situ under various conditions using high-energy synchrotron radiation. As a result, the present inventors surprisingly found that aluminum-iron-based alloys and aluminum-manganese-based alloys, which cannot be expected to function as hydrogen storage alloys according to conventional concepts, can have hydrogen storage properties. rice field. By repeating synchrotron radiation experiments (in-situ observation), the inventors have determined the conditions under which the above alloy has hydrogen storage properties, and have completed the present invention. It should be noted that such a study is only possible when a highly skilled and experienced expert analyzes the data obtained based on a meticulous plan in detail.

When the aluminum-iron alloy in one aspect of the present invention is illustrated and explained, the following has been found. That is, it was found that a specific crystal phase in an aluminum-iron alloy has a hydrogen storage property. Specifically, the crystal phases are a crystal phase having an Al ₁₃ Fe ₄ type crystal structure and a crystal phase having an Al _2.8 Fe type crystal structure. For example, by supplying hydrogen under high temperature and high pressure, the alloy containing these crystal phases can occlude hydrogen. As a compositional range in which the aluminum-iron alloy contains the crystal phase, a range of 0.70≦x≦0.80 is given, where the compositional formula of the alloy is Al _x Fe _(1−x) .

It was also found that when the aluminum-iron alloy is hydrogenated, both the Al ₁₃ Fe ₄ type crystal structure and the Al _2.8 Fe type crystal structure change to different crystal structures. It was also found that the crystal structure after hydrogenation was the same regardless of whether the crystal structure before hydrogenation was the Al ₁₃ Fe ₄ type or Al _2.8 Fe type. Although the above aluminum-iron alloys are known per se, it was not even expected that the alloys would possess hydrogen storage properties. Therefore, a hydride (alloy hydride) having a crystal structure after hydrogenation as described above has not been known in the past, and the above findings are highly unexpected findings that the present inventors have discovered for the first time. .

[Embodiment 1]
One embodiment of the present invention will be described below with reference to the drawings.

<Hydrogen storage material>
The aluminum-iron alloy having a composition having hydrogen storage properties, which the present inventors have discovered, contains aluminum and iron and can be used as a hydrogen storage alloy.

The hydrogen storage material in this embodiment means a material used for hydrogen storage, including the aluminum-iron alloy. The above-mentioned hydrogen storage material is obtained by an original method of combining aluminum and iron, which are base metals which are difficult to hydrogenate, to form an alloy which is easily hydrogenated. The hydrogen storage material in the present embodiment may be made of a hydrogen storage alloy containing an aluminum-iron alloy, or a combination of the hydrogen storage alloy and other substances (for example, other conventionally known hydrogen storage alloys). It may consist of a combination.

(composition and crystal structure)
The alloy (hydrogen storage alloy) contained in the hydrogen storage material in the present embodiment includes a crystal phase having an Al ₁₃ Fe ₄ type crystal structure (hereinafter sometimes referred to as a first crystal phase) and an Al _2.8 Fe type It has one or more crystal phases having a crystal structure of (hereinafter sometimes referred to as a second crystal phase).

Further, the hydrogen storage material in this embodiment includes a hydrogen storage alloy represented by the following compositional formula (1): Al _x Fe _(1-x) (1) (where x is 0.70 or more 0.80 or less, preferably 0.73 or more and 0.78 or less). The composition of the hydrogen storage alloy of the present invention is allowed to contain unavoidable impurities.

The hydrogen storage alloy contained in the hydrogen storage material in the present embodiment has a crystal phase having an Al ₁₃ Fe ₄ type crystal structure when x in the composition formula (1) is in the range of 0.75 or more and 0.78 or less. is formed. Moreover, in the composition in which x in the composition formula (1) is in the range of 0.70 or more and less than 0.75, a crystal phase having an Al _2.8 Fe type crystal structure is formed. This can be confirmed experimentally using X-ray diffraction measurements. It can also be understood with reference to an aluminum-iron binary alloy phase diagram. In addition, the hydrogen storage material in this embodiment should just contain the said hydrogen storage alloy. The crystal phase does not have to be formed as a thermodynamically balanced (stable) phase, so x in the composition formula (1) may be in the range of 0.70 or more and 0.80 or less. Further, as described later, the hydrogen storage alloy in the present embodiment preferably has an Al ₁₃ Fe ₄ type crystal structure, so x in the composition formula (1) is in the range of 0.73 or more and 0.78 or less. Preferably.

The hydrogen storage alloy in this embodiment has a crystal structure after hydrogenation that is changed from the Al ₁₃ Fe ₄ type or Al _2.8 Fe type crystal structure when hydrogen is occluded. By releasing hydrogen from the hydrogen-absorbing alloy after hydrogenation, it returns to the hydrogen-absorbing alloy having the first crystal phase or the second crystal phase. Here, in the X-ray diffraction pattern after the hydrogen release treatment, the width of the diffraction peak may be broadened due to the influence of residual distortion. However, even if the width of the diffraction peak is widened, the diffraction peak position can sometimes be identified. Therefore, it is possible to determine whether or not the object to be measured corresponds to the hydrogen storage alloy of the present embodiment by performing X-ray diffraction measurement of the object to be measured after the hydrogen release process. In some cases, the diffraction peak spreads significantly, making it difficult to specify the diffraction peak position. In this case, it is possible to determine whether or not the object to be measured corresponds to the hydrogen storage alloy of this embodiment by composition analysis.

The value of x in the composition formula (1) may be arbitrarily set within a range in which a crystal phase having an Al ₁₃ Fe ₄ type or Al _2.8 Fe type crystal structure is formed, and the set value of x The above alloy may be produced by mixing aluminum and iron so that the atomic ratio is based on.

It should be noted that the hydrogen storage alloy in the present embodiment only needs to contain one or more of the first crystal phase and the second crystal phase, and the hydrogen storage alloy includes the first crystal phase and the second crystal phase. is not particularly limited. This is because the hydrogen storage alloy of the present embodiment has hydrogen storage properties if it contains the first crystal phase or the second crystal phase.

The hydrogen storage alloy in the present embodiment has a composition in which x is in the range of 0.70 or more and 0.80 or less, and the majority of the alloy is either the first crystal phase or the second crystal phase. can be in the state of Further, in the hydrogen storage alloy of the present embodiment, the first crystal phase and the second crystal phase coexist in a composition in which x is in the range of 0.70 or more and 0.80 or less, and other A crystalline phase may be absent. The hydrogen storage alloy in this embodiment may contain crystal phases other than the first crystal phase and the second crystal phase.

More preferably, the hydrogen storage material of the present embodiment has a composition in which x in the composition formula (1) is in the range of 0.75 or more and 0.78 or less. This is because the first crystalline phase is superior in hydrogen storage characteristics to the second crystalline phase. More preferably, the hydrogen storage alloy in this embodiment is a binary alloy having a composition of Al _0.76 Fe _0.24 . In this case, the hydrogen storage property can be made relatively high, and the hydrogen storage material in this embodiment has, for example, a gravimetric hydrogen density equivalent to that of TiFe, which is one of typical hydrogen storage alloys. Although the above binary alloy with the composition Al _0.76 Fe _0.24 is a known material (e.g. Acta Cryst., 1955, Vol. I wasn't even expected to have it.

(other elements)
The hydrogen storage material and the alloy contained in the hydrogen storage material in this embodiment are allowed to contain impurities that may inevitably be mixed in from raw materials, tools used in the manufacturing process, and the like. That is, the hydrogen storage material may contain unavoidable impurities, for example, when the composition is analyzed, and the composition of the remainder after removing the unavoidable impurities should be within the above range. Examples of unavoidable impurities include elements such as carbon, nitrogen, oxygen, and sulfur contained in aluminum and iron.

Further, when the hydrogen storage material in the present embodiment contains a dissimilar element different from aluminum and iron, the composition range for forming the first crystal phase or the second crystal phase (x range) may fluctuate. The hydrogen storage material is allowed to contain the heteroelement within a range (kind and amount) that does not prevent the formation of the first crystal phase or the second crystal phase. In the hydrogen storage material of the present embodiment, the composition of the remainder excluding the foreign elements and inevitable impurities should be within the above range.

The hydrogen storage material of the present embodiment may contain the first crystal phase or the second crystal phase, and may have a composition outside the range of x in the composition formula (1). .

(Composition analysis method)
The composition of the hydrogen storage material of this embodiment can be analyzed, for example, by the following method. A sample to be measured is embedded in a resin such as Technovit. Next, the cross section is surface-polished using diamond slurry or the like. The resulting polished cross section is subjected to composition analysis using an EDS (energy dispersive X-ray spectrometer) or WDS (angle dispersive X-ray spectrometer) of a scanning electron microscope. As a result of the composition analysis, if the composition of the sample is within the range of x in the above composition formula (1) after considering the error caused by the apparatus, the sample is identified as the hydrogen storage material of this embodiment. can do. At this time, the sample may or may not occlude hydrogen. Further, when the sample is a hydrogen storage material containing the alloy of the present embodiment, if it is determined whether the composition of the alloy phase present in the polished cross section is within the range of x in the above composition formula (1) good.

In addition, the method of said composition analysis is an example. The method is not particularly limited as long as the composition of the hydrogen storage material of the present embodiment can be analyzed. For example, methods such as EPMA (electron probe microanalyzer) and ICP emission spectrometry (high frequency inductively coupled plasma emission spectrometry) may be used.

<Method for producing hydrogen storage material>
An example of the method for producing the hydrogen storage material according to this embodiment will be described below.

First, a mixed powder is prepared by mixing metal powder of aluminum and metal powder of iron weighed so as to have a predetermined ratio. The metal powder of aluminum and the metal powder of iron as raw materials may have a purity of 3N, for example, and may be commercially available. Then, the mixed powder is melted by heating. As a device used for this heating, for example, an electric furnace, an infrared light collecting furnace, or the like can be used. For example, the heating temperature is 1200° C. to 1250° C. and the heating time is 30 seconds to 1 minute. In addition, the above conditions are specific examples, and it is sufficient if an alloy having the first crystal phase or the second crystal phase can be produced. Specific conditions (heating temperature / time, powder particle size, mixing method , etc.) is not particularly limited.

Next, by solidifying the melt obtained by melting the mixed powder, an aluminum-iron alloy can be obtained.

In addition, the raw materials of aluminum and iron are not limited to powders. The raw material may be in the form of, for example, small pieces or flakes.

(Usage form)
The above aluminum-iron alloy may be used after being refined to have a grain size of 1 mm or less. The hydrogen storage material in this embodiment may contain a finely divided aluminum-iron alloy as a hydrogen storage alloy. In this case, the surface area of the hydrogen storage alloy can be increased, which is preferable. The form (size, shape, etc.) of the hydrogen storage alloy contained in the hydrogen storage material in one aspect of the present invention is not particularly limited.

<Hydrogenation>
Hydrogenation of the hydrogen storage material of this embodiment will be described below with reference to FIG. FIG. 1 is a diagram showing an example of the result of observing the hydrogenation reaction process of the hydrogen storage material in this embodiment using synchrotron radiation X-rays.

First, the hydrogen storage material of this embodiment is placed in the high pressure generator. Then, the hydrogen storage material is pressurized to a high pressure of 70,000 atmospheres or higher. Pressurization may be performed, for example, at room temperature, or may be performed at a temperature lower or higher than room temperature, if necessary. Moreover, the pressurization speed can be set arbitrarily because it does not particularly affect the hydrogen storage performance. A known device can be used as the high pressure generator. Such devices include, for example, cubic-type multi-anvil devices. After reaching a predetermined pressure in the high-pressure generator, the hydrogen storage material is heated to 670° C. or higher in a hydrogen fluid. By holding the hydrogen storage material in the hydrogen fluid at high temperature and high pressure, the hydrogen storage material is made to store hydrogen (hydrogen storage step).

By causing the hydrogen storage material of the present embodiment to store hydrogen in the hydrogen storage step, a hydrogen storage material containing hydrogen (hereinafter sometimes referred to as "hydrogen storage material") can be produced. . The time required for hydrogen storage depends on the composition of the hydrogen storage material and the conditions of temperature and pressure, but the higher the temperature, the shorter the reaction time. Moreover, it can be expected that the hydrogenation reaction proceeds rapidly when the pressure is increased and the reaction temperature is raised.

The results of in situ observation of the hydrogenation reaction of the hydrogen storage material in this embodiment using synchrotron radiation X-rays will be described below. Here, a hydrogen storage material having a composition of Al _0.76 Fe _0.24 is used. Also, the X-ray diffraction (XRD) pattern is measured using synchrotron X-rays under conditions of 90,000 atmospheres and 670°C. The XRD patterns were measured before the hydrogenation treatment and 30 seconds, 60 seconds, 90 seconds and 120 seconds after the start of the hydrogenation treatment.

In situ observation using such synchrotron radiation X-rays, only a portion of the sample is observed, so the reaction appears to proceed in a short period of time. However, several tens of minutes or more are required to hydrogenate the entire sample.

As shown in FIG. 1, the XRD pattern of the hydrogen storage material before hydrogen absorption (pattern at the bottom in FIG. 1) has diffraction peaks indicated by black squares in the figure. This corresponds to the XRD pattern of the Al ₁₃ Fe ₄ type crystal structure. The XRD pattern obtained by measurement using synchrotron radiation X-rays under high temperature and pressure conditions may differ slightly in peak position and shape from the XRD pattern at room temperature and normal pressure.

It can be seen that as the elapsed time after the start of the hydrogenation treatment increases, the XRD patterns change in order from the lowest XRD pattern to the highest XRD pattern in FIG. This change in the XRD pattern corresponds to a change in crystal structure due to solid solution of hydrogen in the hydrogen storage material and hydrogenation. As can be seen from this, the uppermost XRD pattern in FIG. 1 shows the crystal structure of the alloy hydride (state in which the alloy is hydrogenated) formed by hydrogenating the hydrogen storage material in this embodiment. . The XRD pattern of the alloy hydride in this embodiment has diffraction peaks indicated by black circles in the figure.

The alloy hydride in this embodiment can be stored in a stable state without reacting with oxygen or moisture in the air when it is taken out into the atmosphere.

<Alloy hydride>
The hydrogen storage material of this embodiment containing hydrogen includes the alloy hydride formed as described above. As an example of the alloy hydride, an alloy hydride obtained by hydrogenating an alloy having a composition of Al _0.76 Fe _0.24 under conditions of 90,000 atmospheres, 750° C., and 2 hours will be described below.

The result of powder X-ray diffraction measurement of the above alloy hydride under normal temperature and normal pressure will be described. Powder X-ray diffraction measurement was performed by a method using synchrotron radiation X-rays.

FIG. 2(a) is a diagram showing an example of an X-ray diffraction pattern obtained by powder X-ray diffraction measurement using synchrotron radiation X-rays for the hydrogen hydride storage material of the present embodiment. FIG. 2(b) is a table showing diffraction peaks in the X-ray diffraction pattern. Measurements were performed as follows. First, the alloy hydride was ground in a mortar for about 15 minutes. The resulting powder was then packed into a Kapton capillary with an inner diameter of 1 mm. Measurements were performed using synchrotron radiation X-rays at the beamline BL22XU of SPring-8, a large synchrotron radiation facility. Specifically, powder X-ray diffraction measurement was performed by irradiating the capillary with synchrotron X-rays under the conditions of an incident X-ray energy of 69.668 keV and a beam size of 200 μm.

As shown in (a) and (b) of FIG. 2, the alloy hydride in the present embodiment has 4.64 Å, 3.79 Å, 2 19 Å and 1.98 Å, showing X-ray diffraction patterns containing at least diffraction peaks corresponding to lattice spacings d of 1.98 Å.

(About errors)
In the above method, the diffraction angle and the lattice spacing d calculated from the diffraction angle may vary depending on the composition of the alloy, the type and amount of impurities, and the like. Therefore, the lattice spacing d (the position of the diffraction peak) allows an error of ±2%. Generally, the error falls within ±1% or less.

(judgement)
Consider the case of determining whether or not an unknown sample (object to be inspected) is an alloy hydride or a hydrogen hydride storage material containing the alloy hydride in the present embodiment. In this case, for example, it is determined whether the result of measuring the powder X-ray diffraction of the test object using the method described above matches the diffraction pattern of the alloy hydride described above or includes the diffraction pattern. . In this determination, an error is allowed as described above.

If the measurement result of powder X-ray diffraction matches the diffraction pattern of the alloy hydride described above, the inspection object can be identified as corresponding to the alloy hydride of the present embodiment. In addition, if it contains the diffraction pattern of the above alloy hydride, it can be identified as corresponding to the hydrogenated hydrogen storage material of the present embodiment. The above method is only an example, and the object to be inspected is the alloy hydride of the present embodiment or a hydrogen hydride storage material containing the alloy hydride by performing X-ray diffraction measurement by another method. Of course, it is also possible to determine whether or not.

(composition analysis)
Whether or not the object to be inspected is the alloy hydride or the hydrogen hydride storage material in this embodiment can also be determined based on the result of composition analysis using the above-described composition analysis method. Specifically, it is determined whether or not the composition of the object to be inspected itself or the alloy contained in the object to be inspected satisfies the condition of the following composition formula (1). If the conditions are satisfied, the test object can be identified as being an alloy hydride or hydrogen hydride storage material in this embodiment;
AlxFe _{(1-x) (} 1)
(Here, x is 0.70 or more and 0.80 or less).

<Method for producing alloy hydride>
An example of the method for producing the alloy hydride of the present embodiment will be described below. First, the hydrogen storage material is enclosed in a pressure medium, and the pressure medium is accommodated in the high pressure generator (accommodation step). A high pressure generator can be, for example, a cubic multi-anvil device. Next, in the high-pressure generator, the hydrogen storage material is pressurized and heated, and a hydrogen fluid is supplied into the pressure medium to hydrogenate the hydrogen storage material (hydrogenation step). In the above hydrogenation step, the following conditions are preferred in order to favorably advance the hydrogenation of the aluminum-iron alloy of the present embodiment. That is, it is preferable to set the pressurization condition to 70,000 atmospheres or more. Moreover, it is preferable to set the heating condition to 670° C. or higher. The heating time is preferably 0.5 hours or more.

<advantageous effect>
Hydrogen release characteristics of the hydrogen storage material in this embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the hydrogen release temperature at normal pressure of the hydrogen storage alloy after hydrogen absorption. Here, a hydrogen storage alloy with a composition of Al _0.76 Fe _0.24 was used.

As shown in FIG. 3, the hydrogen storage alloy after the hydrogenation treatment was heated under normal pressure, and the hydrogen release profile was measured. was done. At about 200° C., hydrogen release of about 2.2% by mass was confirmed. From this, it can be seen that the hydrogen storage material in this embodiment has performance equivalent to hydrogen storage alloys such as LaNi ₅ (approximately 1.3% by mass) and TiFe (approximately 1.8% by mass).

As described above, the hydrogen storage material of the present embodiment is an invention realized by using materials that have not been considered at all in the conventional search guidelines for hydrogen storage alloys. The hydrogen storage material is made only of inexpensive raw materials (base metals) and has excellent hydrogen storage capacity. That is, the hydrogen storage material is made of aluminum and iron, which are produced in large quantities and are extremely inexpensive, and has a gravimetric hydrogen density equivalent to that of hydrogen storage alloys such as LaNi ₅ and TiFe.

Aluminum and iron are very common materials, and the hydrogen storage material in one aspect of the present invention can reduce the raw material cost to a fraction of that of hydrogen storage alloys such as LaNi ₅ and TiFe. . Therefore, it is very advantageous in terms of cost. An example of the application of the hydrogen storage material in one aspect of the present invention is a hydrogen storage tank. Hydrogen storage tanks are suitably used in fuel cell systems for storing and using energy seasonally (seasonally), hydrogen stations, and the like.

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to the drawings. It should be noted that, unless otherwise specified, other aspects than those described in this embodiment are the same as those described in Embodiment 1, and descriptions thereof will be omitted.

In this embodiment, an aluminum-manganese alloy, which is a hydrogen storage alloy contained in the hydrogen storage material according to one aspect of the present invention, will be described.

FIG. 4(a) is a diagram showing an example of an X-ray diffraction pattern obtained by powder X-ray diffraction measurement of a hydrogen storage material containing an aluminum-manganese alloy according to this embodiment. As shown in FIG. 4(a), the aluminum-manganese alloy in this embodiment has a crystal phase having a Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure. The hydrogen storage alloy in this embodiment has a crystal structure after hydrogenation that is changed from the Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure when hydrogen is occluded. By releasing hydrogen from the hydrogen-absorbing alloy after hydrogenation, it returns to the hydrogen-absorbing alloy having a crystal phase having the above-mentioned Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure. By performing X-ray diffraction measurement of the object to be measured after the hydrogen releasing process, it is possible to determine whether or not the object to be measured corresponds to the hydrogen storage alloy of the present embodiment. In some cases, the diffraction peak spreads significantly, making it difficult to specify the diffraction peak position. In this case, it is possible to determine whether or not the object to be measured corresponds to the hydrogen storage alloy of this embodiment by composition analysis.

Further, the hydrogen storage material in the present embodiment contains a hydrogen storage alloy represented by the following compositional formula (2) (however, it is allowed to contain inevitable impurities): Al _y Mn _(1-y) ( 2) (where y is 0.60 or more and 0.70 or less, preferably 0.61 or more and 0.67 or less).

The hydrogen storage alloy contained in the hydrogen storage material in the present embodiment has a composition in which y in the composition formula (2) is in the range of 0.60 or more and 0.70 or less, and is Cr _4.5 (Cr _0.56 Al 0.60) _{. 44} ) A crystalline phase with a crystal structure of the ₉ Al ₁₂ type is formed. This can be confirmed experimentally using X-ray diffraction measurements. In addition, the hydrogen storage material in this embodiment should just contain the said hydrogen storage alloy. The crystalline phase does not have to be formed as a thermodynamically balanced (stable) phase, so y in the compositional formula (2) may be in the range of 0.60 or more and 0.70 or less. In addition, the hydrogen storage alloy contained in the hydrogen storage material in the present embodiment may contain, for example, an alloy of _Mn3.85Al11 of ₅ % by mass or less, and may contain other phases having unknown structures. may be

Since it is preferable that a phase having a Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure is likely to form in the hydrogen storage alloy, y in the composition formula (2) is 0 It is preferably in the range of 0.61 or more and 0.67 or less.

The value of y in the composition formula (2) may be set arbitrarily within a range in which a crystal phase having a Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure is formed. , aluminum and manganese may be mixed so as to have an atomic ratio based on the set value of y to produce the above alloy.

The hydrogen storage material and the alloy contained in the hydrogen storage material of this embodiment are allowed to contain impurities, and their compositions can be analyzed in the same manner as described in the first embodiment. Then, it can be produced by a production method similar to that described in the first embodiment, and can be hydrogenated by using a similar hydrogenation method.

An example of the method for producing the hydrogen storage material according to this embodiment will be described below. That is, a mixed powder is prepared by mixing metal powder of aluminum and metal powder of manganese weighed so as to have a predetermined ratio. The metal powder of aluminum and the metal powder of manganese used as raw materials may have a purity of 3N, for example, and may be commercially available. Then, by heating the mixed powder, an alloy is produced by a solid phase reaction. As a device used for this heating, for example, an electric furnace, an infrared light collecting furnace, or the like can be used. For example, the heating temperature is 780° C. to 810° C., and the heating time is 3 hours to 6 hours. Then, after the mixed powder undergoes a solid phase reaction, the alloy is cooled to room temperature to obtain an aluminum-manganese alloy. The above conditions are specific examples, and it is sufficient if an alloy having a crystal phase having the above Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure can be produced. Conditions (heating temperature/time, particle size of powder, mixing method, etc.) are not particularly limited.

Further, the hydrogenation of the hydrogen storage material in this embodiment is carried out, for example, by housing the hydrogen storage material in a cubic-type multi-anvil apparatus and holding it in a hydrogen fluid under conditions of 90,000 atmospheres and 670°C. It can be done by Further, it has been confirmed that the hydrogen storage material in this embodiment is hydrogenated even under conditions of 40,000 atmospheres and 430°C.

In the method for producing an alloy hydride of the present embodiment, it is preferable to perform the hydrogenation step under the following conditions. That is, it is preferable to set a pressurization condition of 50,000 atmospheres or more and a heating condition of 510° C. or more. The heating time is preferably 3 hours or longer. In the present specification, the term "heating time" refers to the time from reaching the temperature of the heating conditions (set temperature at the time of production) to maintaining the temperature.

The results of in situ observation of the hydrogenation reaction of the hydrogen storage material in this embodiment using synchrotron radiation X-rays will be described below with reference to FIG. 4(b). FIG. 4(b) is a diagram showing an example of the result of observing the hydrogenation reaction process of the hydrogen storage material using synchrotron radiation X-rays. Here, a hydrogen storage material containing an alloy with a composition of Al ₂ Mn is used. Also, the X-ray diffraction (XRD) pattern is measured using synchrotron X-rays under conditions of 90,000 atmospheres and 670°C. XRD patterns were measured at room temperature before heating, before hydrogenation after heating, 10 minutes, 20 minutes, 30 minutes, 40 minutes, and 610 minutes after starting hydrogenation, and at room temperature after cooling. each went.

As shown in FIG. 4(b), the XRD pattern of the hydrogen storage material in the state before hydrogen absorption (pattern at the bottom in FIG. 4(b)) shows diffraction peaks indicated by black triangles in the figure. have The main peak near about 56 keV corresponds to the XRD pattern of the Cr _4.5 (Cr _0.56 Al _0.44 ) ₉ Al ₁₂ type crystal structure (diffraction angle near 19°). It can be seen that the XRD pattern changes in order from the lower XRD pattern toward the upper XRD pattern in FIG. This change in the XRD pattern corresponds to a change in crystal structure due to solid solution of hydrogen in the hydrogen storage material and hydrogenation. As can be seen from this, the uppermost XRD pattern in FIG. 4(b) shows the crystal structure of the alloy hydride formed by hydrogenating the hydrogen storage material in this embodiment. The XRD pattern of the alloy hydride in this embodiment has diffraction peaks indicated by black circles in the figure.

The hydrogen storage material of this embodiment containing hydrogen includes the alloy hydride formed as described above. As an example of the alloy hydride, an alloy hydride obtained by hydrogenating an alloy having a composition of Al ₂ Mn under conditions of 90,000 atmospheres, 670° C., and 610 minutes will be described below.

The result of powder X-ray diffraction measurement of the above alloy hydride under normal temperature and normal pressure will be described. Powder X-ray diffraction measurement was performed by a method using synchrotron radiation X-rays. Specifically, the measurements were performed using synchrotron X-rays at the beamline BL22XU of SPring-8, a large synchrotron radiation facility. The conditions were an incident X-ray wavelength of 0.496406 Å (incident X-ray energy: 24.976 keV) and a beam size of 100 μm.

As shown in (a) and (b) of FIG. 5, the alloy hydride in this embodiment has 5.92 Å, 2.70 Å, 2 1 shows an X-ray diffraction pattern containing at least diffraction peaks corresponding to lattice spacings d of 0.14 Å, 2.12 Å and 2.02 Å.

In the above method, the diffraction angle and the lattice spacing d calculated from the diffraction angle may vary depending on the composition of the alloy, the type and amount of impurities, and the like. Therefore, the lattice spacing d (the position of the diffraction peak) allows an error of ±2%. Generally, the error falls within ±1% or less.

The alloy hydride in this embodiment can be stored in a stable state without reacting with oxygen or moisture in the air when it is taken out into the atmosphere. Also, using the same method as described in the first embodiment, it is determined whether or not the object to be inspected is the alloy hydride of the present embodiment or a hydrogen hydride storage material containing the alloy hydride. be able to.

Hydrogen release characteristics of the hydrogen storage material in this embodiment will be described with reference to FIG. FIG. 6 is a diagram showing the hydrogen release temperature at normal pressure of the hydrogen storage alloy after hydrogen storage in this embodiment. Here, a hydrogen storage alloy with a composition of Al ₂ Mn was used.

As shown in FIG. 6, the hydrogen storage alloy after the hydrogenation treatment was heated under normal pressure, and the hydrogen release profile was measured. was done. Approximately 2.5% by mass of hydrogen release was confirmed. As described above, according to one aspect of the present invention, a hydrogen storage material that can be manufactured using aluminum and manganese as main raw materials and that has hydrogen storage properties (high gravimetric hydrogen density) equivalent to those of conventionally known hydrogen storage alloys. can be provided.

[Embodiment 3]
Other embodiments of the invention are described below. It should be noted that unless otherwise specified, other than what is explained in this embodiment is the same as that explained in the first and second embodiments, and the explanation will be omitted.

In Embodiments 1 and 2, an alloy hydride is produced by hydrogenating a prefabricated hydrogen storage alloy. In contrast, in the present embodiment, a method of manufacturing a hydrogen storage alloy and hydrogenating it in the same process will be described.

Conventionally, there has been known a method of producing a hydrogen-containing hydrogen-absorbing alloy by mixing a metal hydride with another metal and subjecting the mixture to ball milling in a hydrogen atmosphere. In this case, a hydrogenated hydrogen storage alloy can be produced in one step. On the other hand, the hydrogen storage material in one aspect of the present invention includes a hydrogen storage alloy made only of raw materials that are difficult to hydrogenate.

Here, it has been reported that in an Al--Cr alloy composed of aluminum and chromium, under high-temperature and high-pressure conditions (600° C., 90,000 atmospheres), a hydrogenation reaction of Cr occurs and an alloy hydride can be produced. ing. However, in this case, high temperature and high pressure conditions are necessary for the hydrogenation reaction to occur. Therefore, the load on the hydrogenation apparatus is relatively large. Moreover, it is difficult to reduce energy consumption.

Regarding the hydrogen storage alloy (Al--Fe alloy, Al--Mn alloy) according to one aspect of the present invention, there is no known method for producing a hydrogen-containing hydrogen storage alloy in one step.

As a result of intensive studies, the present inventors have found that a mixed powder obtained by mixing different types of difficult-to-hydrogenate metals is placed in a high-temperature and high-pressure state in a hydrogen atmosphere to produce a hydrogen-absorbing alloy according to one aspect of the present invention. We have found that it is possible to manufacture In the method for producing a hydrogen storage alloy according to the present embodiment, a mixed powder obtained by mixing powders of different types of difficult-to-hydrogenate metals at a composition ratio that forms an alloy having hydrogen storage properties when alloyed is prepared in a hydrogen atmosphere. , including the steps of pressurizing and heating.

According to the method for producing a hydrogen-absorbing alloy of the present embodiment, when the different types of difficult-to-hydrogenate metals are Al and Fe, the hydrogen-absorbing material containing an Al—Fe alloy consisting only of base metals can be produced in one step. can be manufactured. Therefore, energy consumption can be reduced and costs can be reduced.

It was also found that when the different metals that are difficult to hydrogenate are Al and Mn, a hydrogen hydride storage material containing an Al—Mn alloy can be produced in one step under relatively low pressure conditions. Therefore, it is possible to reduce the load on the hydrogenation device and reduce the energy consumption. As a result, cost reduction can be achieved.

The method for producing a hydrogen-absorbing alloy according to the present embodiment discovered by the present inventors can be widely and generally applied to the production of a hydrogen-absorbing alloy composed of a metal that is difficult to be hydrogenated. For example, it can be applied to manufacture of an alloy containing Al ₂ Cu as a main component (see Non-Patent Document 1).

A hydrogen storage alloy, which is an aluminum-iron alloy, will be described below.

In the method for producing a hydrogen-absorbing alloy according to the present embodiment, the composition ratio of the mixed powder (dissimilar metals) is Al:Fe=x:(1-x) (where x is 0.70 to 0.70). 80 or less, preferably 0.73 or more and 0.78 or less). The composition of the mixed powder is allowed to contain unavoidable impurities. Specifically, the method for producing a hydrogen storage alloy according to this embodiment includes the following steps.

The mixed powder is prepared, and the mixed powder is enclosed in a pressure medium. Then, the pressure medium is stored in the high pressure generator (accommodation step). Next, the mixed powder is pressurized through the pressure medium in the high pressure generator (pressurization step). Next, the pressurized pressure medium is heated to a temperature at which alloying of the mixed powder proceeds, and a hydrogen fluid is supplied into the pressure medium (hydrogen is generated in the medium). ) to produce an alloy hydride in one step (hydride production process).

The pressure in the pressurizing step is, for example, 90,000 atmospheres or more. The temperature in the hydride production step is, for example, 670° C. to 750° C. In this step, hydrogen is supplied in such an amount that the ratio is, for example, one hydrogen atom per one metal atom. Preferably, hydrogen is supplied in an amount such that there is a ratio of 3 or more hydrogen atoms per metal atom.

As a result, the hydrogen-absorbing alloy (alloy hydride) of the present embodiment in which hydrogen is occluded can be obtained.

In addition, in the method for producing a hydrogen-absorbing alloy according to the present embodiment, when the target is a hydrogen-absorbing alloy that is an aluminum-manganese alloy, the alloy hydride is produced even if the pressure in the pressurizing step is 40,000 atmospheres. be able to. The hydrogenation reaction can proceed under much milder conditions than the Al—Cr alloy described above.

That is, when manufacturing an aluminum-manganese alloy, the pressure in the pressurizing step is, for example, 40,000 atmospheres or more. The temperature in the hydride production step is, for example, 430°C to 500°C. In this step, hydrogen is supplied in an amount such that, for example, the ratio is one or more hydrogen atoms per one metal atom. Preferably, hydrogen is supplied in an amount such that there is a ratio of 3 or more hydrogen atoms per metal atom.

[Embodiment 4]
The hydrogen storage material in one aspect of the present invention is not limited to containing one type of the alloy described in Embodiments 1 and 2, and may contain a plurality of types. That is, the hydrogen storage material in one aspect of the present invention may contain one or more of the aforementioned aluminum-iron alloy and aluminum-manganese alloy. In this case, the hydrogen storage material may be a combination of the various hydrogen storage alloys described above and other substances (for example, other conventionally known hydrogen storage alloys).

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

〔Example〕
An embodiment of the invention is described below. In addition, the present invention is not limited to the following examples.

(Hydrogen storage alloy)
A hydrogen storage alloy was produced according to the following procedure. First, small pieces of aluminum and small pieces of iron or manganese were weighed and mixed so as to have a predetermined composition ratio in terms of atomic ratio. The mixed sample is heated to 1200° C. to 1250° C. (in the case of iron) or 780° C. to 810° C. (in the case of manganese) using an infrared concentrator to obtain an aluminum-iron alloy or aluminum of a predetermined composition. - A manganese-based alloy was produced.

(Hydrogenation method)
An alloy sample was prepared using a predetermined composition ratio. This alloy sample was hydrogenated using a cubic-type multi-anvil apparatus. Since the cubic-type multi-anvil device is a known device, a detailed description of the configuration will be omitted. Using a cubic-type multi-anvil apparatus, the above alloy sample was held under high temperature and high pressure and subjected to hydrogenation treatment. Specific hydrogenation conditions will be described later using tables.

(evaluation)
After the hydrogenation treatment, the temperature and pressure of the apparatus were set to normal temperature and normal pressure, and the sample was collected. The recovered sample was subjected to powder X-ray diffraction measurement, and it was determined based on the XRD pattern whether or not a hydrogen-absorbing alloy in a hydrogen-absorbing state was obtained. A sample in which a hydrogen-absorbing alloy in a hydrogen-absorbing state was obtained was evaluated as ◯, and a sample in which a hydrogen-absorbing alloy was not obtained was evaluated as x.

<Example 1>
An aluminum-iron alloy (Al _0.76 Fe _0.24 alloy) was prepared so as to have a composition of aluminum:iron=76:24 in atomic ratio. The prepared alloy was pressurized to 60,000 to 90,000 atmospheres at room temperature using a cubic-type multi-anvil apparatus. After pressurization was completed, the sample was heated to 505-750° C. in 7-9 minutes and held for 0.5-8 hours. After that, the sample was taken out and examined for the presence or absence of hydrogenation. Table 1 shows the results.

No. in Table 1. 1 to 12, the alloy hydride according to one aspect of the present invention was produced by hydrogenation for 0.5 hours or longer under conditions of 70,000 atmospheres or higher and 670° C. or higher. On the other hand, under the pressurization condition of 60,000 atm, No. 2 was subjected to hydrogenation by holding at a heating temperature of 505 to 670° C. for 2 hours. In Comparative Examples 13 to 16, the hydrogenation reaction did not proceed.

<Example 2>
An aluminum-iron alloy was prepared by weighing so that the composition ratio of aluminum and iron was 73:27 to 78:22 in terms of atomic ratio. The prepared alloy was pressurized to 60,000 to 100,000 atmospheres at room temperature using a cubic-type multi-anvil apparatus. After pressurization was completed, the sample was heated to 670° C. in 8 minutes or 750° C. in 9 minutes and held for 2-24 hours. After that, the sample was taken out and examined for the presence or absence of hydrogenation. Table 2 shows the results.

No. in Table 2. 17 to 25, even when the composition ratio of aluminum and iron varied from 73:27 to 78:22 in terms of atomic ratio, alloy hydrides according to one embodiment of the present invention were produced. On the other hand, no. In Comparative Example 26, the hydrogenation reaction did not proceed.

<Example 3 (Example of Embodiment 2)>
Aluminum-manganese alloys were prepared by weighing so that the composition ratio of aluminum and manganese was 8:5 (61:39) or 2:1 (66:34) in atomic ratio. The prepared alloy was pressurized to 30,000 to 90,000 atmospheres at room temperature using a cubic-type multi-anvil apparatus. After pressurization was completed, the sample was heated to 430° C. to 820° C. and held in a hydrogen fluid (under a hydrogen atmosphere) for 3 to 13 hours. After the hydrogenation treatment, the sample was cooled to room temperature, and the pressure was reduced to normal pressure at room temperature to recover the sample. The presence or absence of hydrogenation was investigated for the recovered sample. Table 3 shows the results.

No. in Table 3. As shown in 31 to 36, alloy hydrides according to one aspect of the present invention were formed even when the composition ratio of aluminum and manganese was changed to 8:5 or 2:1 in terms of atomic ratio. On the other hand, no. Comparative Example No. 37, and No. 37, which was subjected to hydrogenation under a pressurization condition of 40,000 atmospheres and a heating condition of 585° C. for 4 hours. In Comparative Example 38, the hydrogenation reaction did not proceed.

<Example 4 (Example of Embodiment 3)>
A mixed powder was prepared by weighing aluminum powder and iron powder in an atomic ratio of 75:25 and mixing them using an agate mortar. This mixed powder was pressurized to 90,000 atmospheres at room temperature using a cubic-type multi-anvil apparatus. After completion of pressurization to 90,000 atmospheres, the sample was heated to 670° C. in 8 minutes and held in a hydrogen fluid (under a hydrogen atmosphere) for 2 hours. After the hydrogenation treatment, the sample was cooled to room temperature, and the pressure was reduced to normal pressure at room temperature to recover the sample. When powder X-ray diffraction measurement was performed on the recovered sample, it was confirmed that a hydrogen-absorbing alloy in a hydrogen-absorbing state was obtained.

Further, a mixed powder was prepared by weighing aluminum powder and manganese powder in an atomic ratio of 67:33 and mixing them using an agate mortar. This mixed powder was pressurized to 40,000 atmospheres at room temperature using a cubic-type multi-anvil apparatus. After completion of pressurization up to 40,000 atmospheres, the sample was heated to 470° C. in 5 minutes and held in a hydrogen fluid (under a hydrogen atmosphere) for 14 hours. After the hydrogenation treatment, the sample was cooled to room temperature, and the pressure was reduced to normal pressure at room temperature to recover the sample. When powder X-ray diffraction measurement was performed on the recovered sample, it was confirmed that a hydrogen-absorbing alloy in a hydrogen-absorbing state was obtained.

The method of absorbing hydrogen using the hydrogen absorbing material of the present invention can be used, for example, as hydrogen storage means for fuel cell systems.

Claims (5)

A hydrogenated material containing at least one of the alloys represented by the following compositional formulas (1) and (2) (allowing to contain inevitable impurities),
The alloy represented by the following composition formula (1) can be hydrogenated under pressure conditions of 70,000 atmospheres or more, heating conditions of 670 ° C. or more, and heating time conditions of 0.5 hours or more,
The alloy represented by the following compositional formula (2) can be hydrogenated under pressure conditions of 50,000 atmospheres or more, heating conditions of 510 ° C. or more, and heating time conditions of 3 hours or more . Material:
AlxFe _{(1-x) (} 1)
Al _y Mn _(1-y) (2)
(Here, x is 0.70 or more and 0.80 or less, and y is 0.60 or more and 0.70 or less). 2. A hydrogenating material according to claim 1 , characterized in that said alloy comprises a hydrogenated alloy hydride . A method for producing a hydrogenated material , comprising the step of hydrogenating the alloy by supplying hydrogen to the hydrogenated material according to claim 1 under pressurized and heated conditions. A method for producing an alloy hydride,
A mixed powder obtained by mixing aluminum and iron powders in a composition ratio that satisfies the following composition formula (1) (however, it is allowed to contain unavoidable impurities) is pressurized at 90,000 atmospheres or more in a hydrogen atmosphere. A method for producing an alloy hydride, including a step of pressurizing and heating under a heating condition of 670 ° C. or higher:
Al _x Fe _(1-x) ... (1)
(Here, x is 0.70 or more and 0.80 or less). A method for producing an alloy hydride,
A mixed powder obtained by mixing aluminum and manganese powders in a composition ratio that satisfies the following composition formula (2) (however, it is allowed to contain unavoidable impurities) is pressurized at 40,000 atmospheres or more in a hydrogen atmosphere. A method for producing an alloy hydride, including a step of pressurizing and heating under a heating condition of 430 ° C. or higher:
Al _y Mn _(1-y) ... (2)
(Here, y is 0.60 or more and 0.70 or less).

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