JP2007289877A - Hydrogen storage material, manufacturing method thereof and hydride compound material - Google Patents

Hydrogen storage material, manufacturing method thereof and hydride compound material Download PDF

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JP2007289877A
JP2007289877A JP2006121618A JP2006121618A JP2007289877A JP 2007289877 A JP2007289877 A JP 2007289877A JP 2006121618 A JP2006121618 A JP 2006121618A JP 2006121618 A JP2006121618 A JP 2006121618A JP 2007289877 A JP2007289877 A JP 2007289877A
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hydrogen
hydrogen storage
storage material
amount
mixing
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Yasuaki Kawai
泰明 河合
Yoshitsugu Kojima
由継 小島
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Toyota Central R&D Labs Inc
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen storage material capable of storing and releasing hydrogen reversibly at low temperatures without lowering the amount of available hydrogen, its manufacturing method and a hydride compound material. <P>SOLUTION: The manufacturing method comprises a blending process of blending NaH with Al containing 0.05-2.0 mass% of Fe and a crushing/mixing process of crushing and mixing the resultant blend in a non-oxidative atmosphere, and the Fe-containing compound particles are crushed to particle sizes below 10 nm in the crushing/mixing process. The hydrogen storage material consists of a matrix comprising NaH, Al and NaAlH<SB>4</SB>and Fe-containing compound particles dispersed in the matrix, with the particle sizes of the compound particles below 10 nm. A hydride compound material obtained by causing the hydrogen storage material to absorb hydrogen is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、水素吸蔵材料及びその製造方法、並びに水素化物複合体に関し、さらに詳しくは、ＮａＡｌＨ4又はその分解生成物を主成分とし、相対的に低温において可逆的に水素の吸蔵／放出が可能な水素吸蔵材料及びその製造方法、並びに、このような水素吸蔵材料に水素を吸蔵させることにより得られる水素化物複合体に関する。 The present invention relates to a hydrogen storage material, a method for producing the same, and a hydride composite. More specifically, the present invention mainly includes NaAlH 4 or a decomposition product thereof and can reversibly store and release hydrogen at a relatively low temperature. The present invention relates to a hydrogen storage material, a method for producing the same, and a hydride composite obtained by storing hydrogen in such a hydrogen storage material.

近年、二酸化炭素の排出による地球の温暖化等の環境問題や、石油資源の枯渇等のエネルギー問題から、クリーンな代替エネルギーとして水素エネルギーが注目されている。水素は、クリーンであるだけでなく、最も軽い燃料であり、質量当たりのエネルギー密度が大きいという特徴がある。しかしながら、水素は、常温・常圧では気体であり、単位体積当たりのエネルギー貯蔵量が小さいという欠点がある。そのため、水素エネルギーを実用化するためには、水素を安全にかつ効率的に貯蔵、輸送する技術の開発が重要となる。   In recent years, hydrogen energy has attracted attention as a clean alternative energy because of environmental problems such as global warming caused by carbon dioxide emissions and energy problems such as the depletion of petroleum resources. Hydrogen is not only clean, but also the lightest fuel and is characterized by a high energy density per mass. However, hydrogen is a gas at normal temperature and normal pressure, and has a drawback that the amount of stored energy per unit volume is small. Therefore, in order to put hydrogen energy into practical use, it is important to develop technology for storing and transporting hydrogen safely and efficiently.

水素を貯蔵する方法としては、
（１） 高圧の水素ガスを耐圧容器に貯蔵する第１の方法、
（２） 液体水素を断熱容器に貯蔵する第２の方法、
（３） ある種の材料に水素を物理的又は化学的に吸着させる第３の方法、
などが知られている。
これらの内、第１の方法は、耐圧容器の重量が大きく、かつ、水素ガスの圧縮には限界があるので、単位体積当たり及び単位重量当たりの水素密度は相対的に小さい。また、第２の方法は、液化によって水素の体積を大幅に縮小することはできるが、水素の液化に多量のエネルギーを消費し、かつ、液体水素の貯蔵のために特殊な断熱容器が必要となる。これに対し、第３の方法は、液体水素と同等以上の密度で水素を貯蔵でき、かつ、貯蔵のために特殊な容器や多量のエネルギーを必要としないので、輸送可能な水素貯蔵方法として注目されている。 As a method of storing hydrogen,
(1) A first method for storing high-pressure hydrogen gas in a pressure vessel,
(2) a second method for storing liquid hydrogen in an insulated container;
(3) a third method in which hydrogen is physically or chemically adsorbed to a certain material;
Etc. are known.
Among these, in the first method, the weight of the pressure vessel is large and the compression of hydrogen gas is limited, so the hydrogen density per unit volume and unit weight is relatively small. In the second method, the volume of hydrogen can be significantly reduced by liquefaction, but a large amount of energy is consumed for liquefaction of hydrogen, and a special insulated container is required for storage of liquid hydrogen. Become. On the other hand, the third method is capable of storing hydrogen at a density equal to or higher than that of liquid hydrogen, and does not require special containers or a large amount of energy for storage. Has been.

水素を物理的又は化学的に吸着（貯蔵）できる材料としては、具体的には、
（１） 活性炭、フラーレン、ナノチューブ等の炭素材料、
（２） ＬａＮｉ５、ＴｉＦｅ等の水素吸蔵合金、
などが知られている。
これらの内、水素吸蔵合金は、炭素材料に比べて単位体積当たりの水素密度が高いので、水素を貯蔵・輸送するための水素貯蔵材料として有望視されている。しかしながら、ＬａＮｉ５、ＴｉＦｅ等の水素吸蔵合金は、Ｌａ、Ｎｉ、Ｔｉ等の希少金属を含んでいるため、その資源確保が困難であり、コストも高いという問題がある。また、従来の水素吸蔵合金は、合金自体の重量が大きいために、単位重量当たりの水素密度が小さい、すなわち、大量の水素を貯蔵するために極めて重い材料を必要とするという問題がある。 Specific examples of materials that can physically or chemically adsorb (store) hydrogen include:
(1) Carbon materials such as activated carbon, fullerene and nanotubes,
(2) Hydrogen storage alloys such as LaNi 5 and TiFe,
Etc. are known.
Among these, hydrogen storage alloys are promising as hydrogen storage materials for storing and transporting hydrogen because they have a higher hydrogen density per unit volume than carbon materials. However, since hydrogen storage alloys such as LaNi 5 and TiFe contain rare metals such as La, Ni, and Ti, there are problems that it is difficult to secure resources and the cost is high. In addition, the conventional hydrogen storage alloy has a problem that since the weight of the alloy itself is large, the hydrogen density per unit weight is small, that is, an extremely heavy material is required to store a large amount of hydrogen.

そこでこの問題を解決するために、軽元素を含む各種の水素吸蔵材料の開発が試みられている。
例えば、非特許文献１には、ＮａＨ（９５％、〜２００メッシュ）、Ａｌ粉末（９９．９５＋％、〜２００メッシュ）、及びＴｉ粉末（９９．９８％、〜３２５メッシュ）を１：１：０．０４のモル比で配合し、水素雰囲気下（０．８ＭＰａ）又はアルゴン雰囲気下（０．１ＭＰａ）において遊星ボールミルで粉砕混合することにより得られるＴｉドープＮａＡｌＨ4が開示されている。同文献には、このような方法により得られるＴｉドープＮａＡｌＨ4は、水素を可逆的に吸蔵／放出することができる点が記載されている。 In order to solve this problem, development of various hydrogen storage materials containing light elements has been attempted.
For example, Non-Patent Document 1 includes NaH (95%, ˜200 mesh), Al powder (99.95 +%, ˜200 mesh), and Ti powder (99.98%, ˜325 mesh) 1: 1: A Ti-doped NaAlH 4 obtained by blending at a molar ratio of 0.04 and pulverizing and mixing with a planetary ball mill in a hydrogen atmosphere (0.8 MPa) or an argon atmosphere (0.1 MPa) is disclosed. This document describes that Ti-doped NaAlH 4 obtained by such a method can reversibly absorb and release hydrogen.

また、特許文献１には、ＬｉＨ粒子（純度９０％以上、粒径８０μｍ以下）、Ａｌ粒子（純度９９％、粒径８０μｍ以下）、及びＴｉＨ2粒子（純度９９％、粒径５０〜３００ｎｍ）を４８：４８：４のモル比で配合し、水素雰囲気下（２．０ＭＰａ）において横型ボールミルで粉砕混合することにより得られる水素貯蔵材粉末が開示されている。同文献には、このような方法により得られる水素貯蔵材粉末は、水素を可逆的に吸蔵／放出することができる点が記載されている。
さらに、非特許文献２には、各種の触媒を用いて固相反応により合成されたＮａ2ＬｉＡｌＨ6が開示されている。同文献には、各種の触媒を添加することによって水素の吸蔵／放出が可能となるが、有効水素量が低下（２〜２．５ｗｔ％）し、水素の吸蔵／放出温度も２３０℃に上昇する点が記載されている。 Patent Document 1 discloses LiH particles (purity 90% or more, particle size 80 μm or less), Al particles (purity 99%, particle size 80 μm or less), and TiH 2 particles (purity 99%, particle size 50 to 300 nm). Is stored in a molar ratio of 48: 48: 4, and a hydrogen storage material powder obtained by pulverizing and mixing with a horizontal ball mill in a hydrogen atmosphere (2.0 MPa) is disclosed. This document describes that the hydrogen storage material powder obtained by such a method can reversibly store and release hydrogen.
Further, Non-Patent Document 2 discloses Na 2 LiAlH 6 synthesized by solid phase reaction using various catalysts. In this document, hydrogen can be occluded / released by adding various catalysts, but the amount of effective hydrogen decreases (2 to 2.5 wt%), and the hydrogen occlusion / release temperature rises to 230 ° C. The point to do is described.

J.Phys.Chem.B 2004, 108, 15827-15829J.Phys.Chem.B 2004, 108, 15827-15829 特開２００４−２８３６９４号公報JP 2004-283694 A Journal of Alloys and Compounds 404-406(2005)771-774Journal of Alloys and Compounds 404-406 (2005) 771-774

Ｎａ、Ｌｉなどの軽元素を含む水素吸蔵材料は、単位重量当たりの水素密度が高いという利点がある。しかしながら、軽元素を含む水素吸蔵材料は、貯蔵した水素の放出のみが可能なものが多く、可逆的に水素を吸蔵／放出できるものが少ない。
ＮａＡｌＨ4は、単独では水素を可逆的に吸蔵／放出することはできないが、Ｔｉを触媒として添加すると、可逆的な水素の吸蔵／放出が可能となる材料の１つである（非特許文献１参照）。しかしながら、原料粉末に触媒粉末を加えて混合粉砕する方法では、触媒微粒子の微細化及び高分散化に限界がある。そのため、相対的に高い性能を得るためには、相対的に多量の触媒の添加が必要になる。また、Ｔｉは、一般に高価である。
一方、特許文献１には、ＴｉＨ2超微粒子の存在下で固相合成されたＬｉＡｌＨ4は、水素を可逆的に吸蔵／放出できる点が記載されている。しかしながら、本願発明者らが追試を行ったところでは、水素の可逆的な吸蔵／放出は確認できなかった。
さらに、有効水素量を低下させずに、より低温での水素吸蔵／放出が可能なＡｌ系水素吸蔵材料、及びこのような材料を簡便に製造する方法が提案された例は、従来にはない。 A hydrogen storage material containing light elements such as Na and Li has an advantage of high hydrogen density per unit weight. However, many hydrogen storage materials containing light elements can only release stored hydrogen, and few can reversibly store and release hydrogen.
NaAlH 4 alone cannot absorb / release hydrogen reversibly, but is one of the materials that can reversibly store / release hydrogen when Ti is added as a catalyst (Non-Patent Document 1). reference). However, the method of adding and mixing and pulverizing the catalyst powder to the raw material powder has a limit to the refinement and high dispersion of the catalyst fine particles. Therefore, in order to obtain relatively high performance, it is necessary to add a relatively large amount of catalyst. Ti is generally expensive.
On the other hand, Patent Document 1 describes that LiAlH 4 synthesized in the solid phase in the presence of TiH 2 ultrafine particles can reversibly absorb and release hydrogen. However, reversible storage / release of hydrogen could not be confirmed when the inventors of the present application conducted a follow-up test.
Further, there has never been an example in which an Al-based hydrogen storage material capable of storing / releasing hydrogen at a lower temperature without reducing the effective hydrogen amount and a method for easily producing such a material have been proposed. .

本発明が解決しようとする課題は、可逆的な水素の吸蔵／放出が可能な水素吸蔵材料及びその製造方法、並びに、このような水素吸蔵材料に水素を吸蔵させることにより得られる水素化物複合体を提供することにある。
また、本発明が解決しようとする他の課題は、低コストであり、かつ、有効水素量を低下させることなく、より低温での可逆的な水素の吸蔵／放出が可能な水素吸蔵材料及びその製造方法、並びに、水素化物複合体を提供することにある。 The problem to be solved by the present invention is a hydrogen storage material capable of reversibly storing / releasing hydrogen, a method for producing the same, and a hydride composite obtained by storing such a hydrogen storage material with hydrogen. Is to provide.
Another problem to be solved by the present invention is a hydrogen storage material that is low in cost and capable of reversibly storing / releasing hydrogen at a lower temperature without reducing the amount of effective hydrogen, and its It is in providing a manufacturing method and a hydride composite.

上記課題を解決するために本発明に係る水素吸蔵材料の製造方法は、ＮａＨと、０．０５ｍａｓｓ％以上２．０ｍａｓｓ％以下のＦｅを含むＡｌとを配合する配合工程と、前記配合工程で得られた配合物を非酸化雰囲気下において粉砕混合する粉砕混合工程を備え、前記粉砕混合工程は、Ｆｅを含む複合粒子の粒径が１０ｎｍ未満となるように、前記粉砕混合を行うものであることを要旨とする。
また、本発明に係る水素吸蔵材料は、ＮａＨと、Ａｌと、ＮａＡｌＨ4との混合物からなるマトリックスと、前記マトリックス中に分散しているＦｅを含む複合粒子とを備え、前記複合粒子の粒径は、１０ｎｍ未満であることを要旨とする。
さらに、本発明に係る水素化物複合体は、本発明に係る水素吸蔵材料に水素を吸蔵させることにより得られるものからなる。 In order to solve the above problems, a method for producing a hydrogen storage material according to the present invention is obtained by a blending step of blending NaH and Al containing 0.05 mass% or more and 2.0 mass% or less of Fe, and the blending step. A pulverizing and mixing step of pulverizing and mixing the resulting blend in a non-oxidizing atmosphere, wherein the pulverizing and mixing step is to perform the pulverizing and mixing so that the particle size of the composite particles containing Fe is less than 10 nm. Is the gist.
The hydrogen storage material according to the present invention includes a matrix made of a mixture of NaH, Al, and NaAlH 4, and composite particles containing Fe dispersed in the matrix, and the particle size of the composite particles Is summarized as being less than 10 nm.
Furthermore, the hydride composite according to the present invention is obtained by storing hydrogen in the hydrogen storage material according to the present invention.

ＮａＨとＡｌから固相反応によりＮａＡｌＨ4を合成する場合において、所定量のＦｅを不純物として含むＡｌを出発原料に用いると、Ｆｅを含む複合粒子が均一に分散した水素吸蔵材料が得られる。Ｆｅを含む複合粒子は、ＮａＡｌＨ4が水素を放出し、又は、ＮａＡｌＨ4の分解生成物が水素を再吸蔵する際に触媒として機能する。しかも、Ｆｅは、あらかじめ微粒子としてＡｌ中に含まれているので、粉砕混合条件を最適化することによって、複合粒子の粒径を容易に１０ｎｍ未満にすることができる。そのため、複合粒子の量が極めて少量であっても、高い触媒能を発揮する。また、有効水素量を低下させることなく、より低温での可逆的な水素の吸蔵／放出が可能となる。 In the case of synthesizing NaAlH 4 from NaH and Al by solid phase reaction, when Al containing a predetermined amount of Fe as an impurity is used as a starting material, a hydrogen storage material in which composite particles containing Fe are uniformly dispersed can be obtained. Composite particles containing Fe is, NaAlH 4 is release hydrogen, or degradation products of NaAlH 4 functions as a catalyst when re storing hydrogen. Moreover, since Fe is already contained in Al as fine particles, the particle size of the composite particles can be easily reduced to less than 10 nm by optimizing the pulverization and mixing conditions. Therefore, even if the amount of the composite particles is very small, high catalytic ability is exhibited. In addition, reversible hydrogen storage / release at a lower temperature is possible without reducing the effective hydrogen amount.

以下、本発明の一実施の形態について詳細に説明する。
本発明に係る水素吸蔵材料は、マトリックスと、マトリックス中に分散している複合粒子とを備えている。
「マトリックス」とは、ＮａＨと、Ａｌと、ＮａＡｌＨ4との混合物をいう。本発明に係る水素吸蔵材料は、後述するように、ＮａＨと所定量のＦｅを含むＡｌを粉砕混合することにより得られる。そのため、水素吸蔵材料中には、微細に粉砕されたＮａＨとＡｌの混合物の他に、固相反応により生成したＮａＡｌＨ4が含まれる。粉砕直後の材料中に含まれるＮａＡｌＨ4の粒径及び量は、粉砕条件により異なる。後述する条件下では、粉砕直後のＮａＡｌＨ4の粒径は、数十μｍ程度となる。 Hereinafter, an embodiment of the present invention will be described in detail.
The hydrogen storage material according to the present invention includes a matrix and composite particles dispersed in the matrix.
“Matrix” refers to a mixture of NaH, Al, and NaAlH 4 . As will be described later, the hydrogen storage material according to the present invention is obtained by pulverizing and mixing Al containing NaH and a predetermined amount of Fe. Therefore, the hydrogen storage material contains NaAlH 4 produced by a solid phase reaction in addition to a finely pulverized mixture of NaH and Al. The particle size and amount of NaAlH 4 contained in the material immediately after pulverization vary depending on the pulverization conditions. Under the conditions described later, the particle size of NaAlH 4 immediately after pulverization is about several tens of μm.

「複合粒子」とは、主成分としてＦｅを含む微粒子をいう。複合粒子は、出発原料中に予め添加されるものではなく、出発原料であるＡｌに不純物として含まれるＦｅが粉砕される過程で複合粒子となる。
複合粒子は、実質的にＦｅのみからなるものでも良く、あるいは、Ｆｅと他の金属又は半金属との混合物であっても良い。また、複合粒子は、Ｆｅに加えて又はこれに代えて、Ｆｅを含む合金又は化合物が含まれていても良い。
複合粒子に含まれる他の金属、半金属、化合物としては、以下のようなものがある。
（１） 出発原料であるＡｌに不純物として含まれるＳｉ。
（２） 粉砕容器又は粉砕媒体から混入する金属若しくは化合物（例えば、Ｆｅ3Ｃ、Ｃｒなど）。
なお、Ｆｅ3Ｃ、Ｃｒなどの遷移金属又はその化合物は、ＮａＡｌＨ4の水素の吸蔵／放出反応を促進させる触媒能を持つ。一方、Ｓｉは、ＮａＡｌＨ4の水素の吸蔵／放出反応を促進させる触媒能はないが、吸蔵／放出反応を阻害することもないので、複合粒子に含まれていても良い。 “Composite particles” refers to fine particles containing Fe as a main component. The composite particles are not added in advance to the starting material, but become composite particles in the process of pulverizing Fe contained as impurities in the starting material Al.
The composite particles may be substantially composed only of Fe, or may be a mixture of Fe and other metals or metalloids. Further, the composite particles may contain an alloy or compound containing Fe in addition to or instead of Fe.
Examples of other metals, metalloids and compounds contained in the composite particles are as follows.
(1) Si contained as an impurity in Al as a starting material.
(2) Metal or compound (for example, Fe 3 C, Cr, etc.) mixed from the grinding container or grinding medium.
Note that transition metals such as Fe 3 C and Cr or compounds thereof have catalytic ability to promote the hydrogen storage / release reaction of NaAlH 4 . On the other hand, Si does not have a catalytic ability to promote the hydrogen occlusion / release reaction of NaAlH 4 , but does not inhibit the occlusion / release reaction, so Si may be contained in the composite particles.

複合粒子の粒径は、１０ｎｍ未満が好ましい。複合粒子の粒径が１０ｎｍ以上になると、触媒活性が低下するので、高い触媒能を得るためには、相対的に多量の複合粒子が必要となる。複合粒子の粒径は、さらに好ましくは、５ｎｍ以下である。   The particle size of the composite particles is preferably less than 10 nm. When the particle size of the composite particles is 10 nm or more, the catalytic activity decreases, so that a relatively large amount of composite particles is required to obtain high catalytic ability. The particle size of the composite particles is more preferably 5 nm or less.

一般に、水素吸蔵材料中に含まれる複合粒子の量が多くなるほど、可逆的な水素の吸蔵／放出が容易化する。また、複合粒子の粒径が小さくなるほど、相対的に少量で高い触媒能が得られる。本発明に係る複合粒子は、極めて微細であるので、その量が０．１モル％未満であっても極めて高い触媒能が得られる。複合粒子の量は、さらに好ましくは、０．０５モル％以下である。
一方、水素吸蔵材料中に含まれる複合粒子の量が少なくなりすぎると、水素の吸蔵／放出温度が上昇し、あるいは、可逆的な水素の吸蔵／放出が困難となる。可逆的な水素の吸蔵／放出を容易化するためには、水素吸蔵材料中に含まれる複合粒子の量は、０．００１モル％以上が好ましい。複合粒子の量は、さらに好ましくは、０．０１モル％以上である。
なお、「複合粒子の量（モル％）」とは、水素吸蔵材料を構成する主元素であるＮａのモル数（ｘ）及びＡｌのモル数（ｙ）に対するＦｅのモル数（ｚ）の割合（＝ｚ×１００／（ｘ＋ｙ））をいう。 In general, as the amount of composite particles contained in the hydrogen storage material increases, reversible hydrogen storage / release is facilitated. Moreover, as the particle size of the composite particles becomes smaller, higher catalytic ability can be obtained with a relatively small amount. Since the composite particles according to the present invention are extremely fine, even if the amount is less than 0.1 mol%, extremely high catalytic ability can be obtained. More preferably, the amount of the composite particles is 0.05 mol% or less.
On the other hand, if the amount of the composite particles contained in the hydrogen storage material is too small, the hydrogen storage / release temperature rises, or reversible hydrogen storage / release becomes difficult. In order to facilitate reversible hydrogen storage / release, the amount of the composite particles contained in the hydrogen storage material is preferably 0.001 mol% or more. The amount of the composite particles is more preferably 0.01 mol% or more.
The “amount of composite particles (mol%)” is the ratio of the mole number (z) of Fe to the mole number (x) of Na, which is the main element constituting the hydrogen storage material, and the mole number (y) of Al. (= Z × 100 / (x + y)).

図１に、本発明に係る水素吸蔵材料（粉砕直後）の概念図を示す。粉砕直後の水素吸蔵材料は、主原料であるＮａＨ及びＡｌの微細な混合物に加えて、固相反応により生成した数十μｍ程度のＮａＡｌＨ4を含む。また、主原料の粉砕混合の過程で生じた１０ｎｍ未満の微細な複合粒子がマトリックス（ＮａＨ、Ａｌ及びＮａＡｌＨ4の混合物）中に均一に分散した状態になっている。 In FIG. 1, the conceptual diagram of the hydrogen storage material (just after grinding | pulverization) which concerns on this invention is shown. The hydrogen storage material immediately after pulverization includes NaAlH 4 of about several tens of μm produced by solid-phase reaction in addition to a fine mixture of NaH and Al which are main raw materials. Further, fine composite particles of less than 10 nm generated in the course of pulverization and mixing of the main raw material are uniformly dispersed in the matrix (mixture of NaH, Al and NaAlH 4 ).

ＮａＡｌＨ4の水素吸蔵／放出反応は、周知のように、次の（１）式で表される。
ＮａＡｌＨ4⇔1/3Ｎａ3ＡｌＨ6＋2/3Ａｌ＋Ｈ2⇔ＮａＨ＋Ａｌ＋3/2Ｈ2 ・・・（１）
図１に示す組織を有する水素吸蔵材料に対して水素を吸蔵させると、（１）式の左側に向かって反応が進行する。すなわち、マトリックス中に残存しているＮａＨ及びＡｌがＨ2と反応し、ＮａＡｌＨ4となる。この時、吸蔵条件を最適化すると、理想的には、マトリックス全体がＮａＡｌＨ4に変化した水素化物複合体となる。
一方、水素化物複合体を所定の温度に加熱すると、（１）式の右側に向かって反応が進行し、水素を放出する。その結果、マトリックス中のＮａＡｌＨ4の全部又は一部がＮａ3ＡｌＨ6、ＮａＨ又はＡｌに分解する。また、放出条件を最適化すると、理想的には、マトリックス全体がＮａＨとＡｌの混合物に変化した水素吸蔵材料となる。
なお、本発明において、「水素吸蔵材料」とは、水素ガスを吸蔵する能力を有するものをいう。「水素吸蔵材料」という時は、水素を完全に放出した材料だけでなく、最大吸蔵量に満たない水素を吸蔵している材料も含まれる。
また、本発明において、「水素化物複合体」とは、ＮａＡｌＨ4を含む複合体であって、水素ガスを放出する能力を有するものをいう。 As is well known, the hydrogen storage / release reaction of NaAlH 4 is expressed by the following equation (1).
NaAlH 4 ⇔1 / 3Na 3 AlH 6 + 2 / 3Al + H 2 ⇔NaH + Al + 3 / 2H 2 (1)
When hydrogen is stored in the hydrogen storage material having the structure shown in FIG. 1, the reaction proceeds toward the left side of the equation (1). That is, NaH and Al remaining in the matrix react with H 2 to become NaAlH 4 . If the occlusion conditions are optimized at this time, ideally, the entire matrix becomes a hydride complex changed to NaAlH 4 .
On the other hand, when the hydride complex is heated to a predetermined temperature, the reaction proceeds toward the right side of the formula (1) to release hydrogen. As a result, all or part of NaAlH 4 in the matrix is decomposed into Na 3 AlH 6 , NaH or Al. Moreover, when the release conditions are optimized, ideally, the entire matrix becomes a hydrogen storage material that is changed to a mixture of NaH and Al.
In the present invention, the “hydrogen storage material” refers to a material having the ability to store hydrogen gas. The term “hydrogen storage material” includes not only a material that completely releases hydrogen but also a material that stores hydrogen that is less than the maximum storage amount.
In the present invention, the “hydride complex” refers to a complex containing NaAlH 4 and capable of releasing hydrogen gas.

次に、本発明に係る水素吸蔵材料の製造方法について説明する。
本発明に係る水素吸蔵材料の製造方法は、配合工程と、粉砕混合工程とを備えている。
配合工程は、ＮａＨとＡｌとを所定の比率で配合する工程である。
出発原料であるＮａＨとＡｌの形態は、特に限定されるものではないが、通常は、粉末を用いる。また、出発原料として粉末を用いる場合、その粒径は、特に限定されるものではない。一般に、出発原料として粒径の細かい粉末を用いるほど、粉砕混合の際の負荷を軽減することができる。一方、必要以上に細かい粉末を出発原料として用いると、粉末表面が酸化等により被毒されるおそれがある。従って、粉末の粒径は、作業性、コスト、被毒の有無等を考慮して、最適な粒径を選択するのが好ましい。 Next, the manufacturing method of the hydrogen storage material which concerns on this invention is demonstrated.
The method for producing a hydrogen storage material according to the present invention includes a blending step and a pulverizing and mixing step.
The blending step is a step of blending NaH and Al at a predetermined ratio.
The form of NaH and Al as starting materials is not particularly limited, but usually powder is used. Moreover, when using powder as a starting material, the particle size is not specifically limited. In general, the load at the time of pulverization and mixing can be reduced as the powder having a smaller particle diameter is used as a starting material. On the other hand, if a finer powder than necessary is used as a starting material, the powder surface may be poisoned by oxidation or the like. Therefore, it is preferable to select an optimum particle size in consideration of workability, cost, presence / absence of poisoning, and the like.

工業的に生産されるＮａＨには、一般に、不純物として、Ｃａ、Ｋ、Ａｌ、Ｂなどが含まれている。これらは、いずれも、水素吸蔵／放出反応を阻害する作用はないが、少ない方が好ましい。原料として用いるＮａＨの純度は、９５％以上が好ましく、さらに好ましくは、９９％以上である。
Ａｌには、所定量のＦｅを含むものを用いる。Ａｌ中に不純物として含まれるＦｅが複合微粒子の主要構成元素となる。水素の吸蔵／放出反応を容易化するためには、Ａｌ中に含まれるＦｅの量は、０．０５ｍａｓｓ％以上が好ましい。Ｆｅ量は、さらに好ましくは、０．０８ｍａｓｓ％以上である。一方、過剰のＦｅを含むＡｌは、実益が無いだけでなく、入手も困難である。従って、Ｆｅ量は、２．０ｍａｓｓ％以下が好ましく、さらに好ましくは、１．５ｍａｓｓ％以下である。
このような条件を満たすＡｌとしては、純度が９９％以上９９．９５％未満の純Ａｌ（ＪＩＳ １０５０、１０６０、１０７０、１１００、１２００相当）、市販のＡｌホイル、タブレット、ワイヤー、小径棒、条（リボン）などがある。 Industrially produced NaH generally contains Ca, K, Al, B, etc. as impurities. None of these has an effect of inhibiting the hydrogen storage / release reaction, but a smaller amount is preferable. The purity of NaH used as a raw material is preferably 95% or more, and more preferably 99% or more.
Al containing a predetermined amount of Fe is used. Fe contained as an impurity in Al is a main constituent element of the composite fine particles. In order to facilitate the hydrogen storage / release reaction, the amount of Fe contained in Al is preferably 0.05 mass% or more. The amount of Fe is more preferably 0.08 mass% or more. On the other hand, Al containing excess Fe not only has no practical benefit, but is also difficult to obtain. Therefore, the Fe amount is preferably 2.0 mass% or less, and more preferably 1.5 mass% or less.
As Al satisfying such conditions, pure Al (equivalent to JIS 1050, 1060, 1070, 1100, 1200) having a purity of 99% or more and less than 99.95%, commercially available Al foil, tablet, wire, small-diameter bar, strip (Ribbon).

ＮａＨとＡｌの配合比は、理想的にはモル比で１：１であるが、化学量論比から若干ずれていても良い。但し、化学量論比からのずれが大きくなりすぎると、反応に消費されない原料が残り、材料全体の水素吸蔵量が低下する。従って、ＮａＨとＡｌの配合比は、化学量論比に近く、かつ、複合粒子のモル数が所定の範囲となるように、出発原料の純度に応じて最適な配合比を選択する。   The mixing ratio of NaH and Al is ideally 1: 1 as a molar ratio, but may be slightly deviated from the stoichiometric ratio. However, if the deviation from the stoichiometric ratio becomes too large, raw materials that are not consumed in the reaction remain, and the hydrogen storage amount of the entire material decreases. Therefore, the mixing ratio of NaH and Al is close to the stoichiometric ratio, and the optimal mixing ratio is selected according to the purity of the starting material so that the number of moles of the composite particles is within a predetermined range.

粉砕混合工程は、配合工程で得られた配合物を非酸化雰囲気下において粉砕混合する工程である。
粉砕混合は、粉砕容器の中に配合物及び粉砕媒体（例えば、ボール）を入れ、粉砕媒体を介して配合物に機械的応力を加えることにより行う。これにより、配合物が微細に粉砕され、かつ均一に混合されると同時に、固相反応が部分的に進行する。
粉砕混合方法は、特に限定されるものではなく、相対的に大きな機械的エネルギーを配合物に加えられるものであればよい。使用する粉砕機としては、具体的には、遊星ボールミル、回転ミル、振動ミルなどが好適である。 The pulverization / mixing step is a step of pulverizing and mixing the compound obtained in the compounding step in a non-oxidizing atmosphere.
Crushing and mixing is performed by placing the formulation and grinding media (eg, balls) in a grinding vessel and applying mechanical stress to the formulation through the grinding media. As a result, the compound is finely pulverized and uniformly mixed, and at the same time, the solid-phase reaction partially proceeds.
The pulverization and mixing method is not particularly limited as long as relatively large mechanical energy can be added to the blend. Specifically, as the grinder to be used, a planetary ball mill, a rotary mill, a vibration mill, or the like is preferable.

粉砕容器及び粉砕媒体の材料には、
（１） クロムモリブデン鋼、ニッケルクロム鋼、ニッケルクロムモリブデン鋼、高炭素鋼などのクロムを含有する高炭素な鋼、
（２） ジルコニアなどのセラミックス、
などを用いることができる。また、粉砕媒体は、上述した材料のいずれか１種のみからなるものでも良く、あるいは、２種以上を組み合わせて用いても良い。
さらに、粉砕媒体の表面に、所定量のＦｅを含むＡｌをコーティング、メッキなどの手段であらかじめ付着させておいても良い。粉砕媒体表面をＡｌで被覆すると、粉砕混合時にＡｌ層が摩砕され、原料中にＦｅを効率よく混入させることができる。 For the material of the grinding container and grinding media,
(1) High carbon steel containing chromium, such as chromium molybdenum steel, nickel chromium steel, nickel chromium molybdenum steel, high carbon steel,
(2) Ceramics such as zirconia,
Etc. can be used. Further, the grinding medium may be composed of only one of the materials described above, or may be used in combination of two or more.
Further, Al containing a predetermined amount of Fe may be preliminarily adhered to the surface of the grinding medium by means such as coating or plating. When the grinding medium surface is coated with Al, the Al layer is ground during grinding and mixing, and Fe can be efficiently mixed into the raw material.

粉砕混合は、Ｆｅを含む複合粒子の粒径が１０ｎｍ未満となるように行う。一般に、別個の触媒粒子を配合物に加えて粉砕混合する場合、触媒粒子の粒径を１０ｎｍ未満にするのは容易でない。これに対し、本発明においては、Ａｌ中に不純物として含まれるＦｅを利用するので、複合粒子の粒径を比較的容易に１０ｎｍ以下にすることができる。
具体的な粉砕条件は、粉砕方法により異なる。一般に、粉砕時の加速度が大きくなるほど、短時間で複合粒子の粒径を１０ｎｍ以下にすることができる。例えば、遊星ボールミルを用いて加速度２〜６Ｇの条件下で粉砕する場合、粉砕時間は、５時間以上が好ましく、さらに好ましくは、１０時間以上である。 The pulverization and mixing is performed so that the particle diameter of the composite particles containing Fe is less than 10 nm. Generally, when adding separate catalyst particles to the formulation and pulverizing and mixing, it is not easy to make the particle size of the catalyst particles less than 10 nm. On the other hand, in the present invention, since Fe contained as an impurity in Al is used, the particle size of the composite particles can be relatively easily reduced to 10 nm or less.
Specific grinding conditions vary depending on the grinding method. In general, the larger the acceleration during pulverization, the shorter the composite particle size can be 10 nm or less. For example, when pulverizing under the condition of acceleration of 2 to 6 G using a planetary ball mill, the pulverization time is preferably 5 hours or more, and more preferably 10 hours or more.

粉砕混合は、非酸化雰囲気下で行う。粉砕時の雰囲気としては、具体的には、
（１） 不活性ガス雰囲気（例えば、アルゴン）、
（２） 水素雰囲気、
などがある。本発明においては、いずれの雰囲気を用いても良い。
特に、水素雰囲気下で粉砕混合を行うと、その理由の詳細は不明であるが、不活性ガス雰囲気下で粉砕混合する場合に比べて、水素の吸蔵／放出特性が向上する。水素雰囲気下で粉砕混合する場合、水素雰囲気圧は、０．２〜１ＭＰａが好ましい。 The pulverization and mixing are performed in a non-oxidizing atmosphere. Specifically, the atmosphere during grinding is as follows:
(1) Inert gas atmosphere (for example, argon),
(2) Hydrogen atmosphere,
and so on. Any atmosphere may be used in the present invention.
In particular, when the pulverization and mixing is performed in a hydrogen atmosphere, the details of the reason are unclear, but the hydrogen storage / release characteristics are improved as compared with the case of pulverizing and mixing in an inert gas atmosphere. When pulverizing and mixing in a hydrogen atmosphere, the hydrogen atmosphere pressure is preferably 0.2 to 1 MPa.

このようにして得られた水素吸蔵材料は、粉末状態のまま使用しても良く、あるいは、これを適当な大きさに成形した圧粉体の状態で使用しても良い。また、粉末の表面を他の材料（例えば、銅などの熱伝導性の良い材料）からなる被膜で被覆し、これを成形して使用しても良い。この場合、被覆方法には、ＰＶＤ法、ＣＶＤ法などの物理的方法を用いるのが好ましい。   The hydrogen storage material thus obtained may be used in a powder state, or may be used in the form of a green compact obtained by molding it into an appropriate size. Alternatively, the surface of the powder may be coated with a film made of another material (for example, a material having good thermal conductivity such as copper) and used after being molded. In this case, it is preferable to use a physical method such as a PVD method or a CVD method as the coating method.

次に、本発明に係る水素吸蔵材料及びその製造方法の作用について説明する。
ＮａＡｌＨ4は、単独では、水素を可逆的に吸蔵／放出することはできないが、触媒が共存すると、水素を可逆的に吸蔵／放出する。この場合、高い触媒活性を得るには、相対的に多量の触媒を添加するか、あるいは、触媒を微細化する必要がある。しかしながら、非特許文献１に開示されているように、原料配合物にＴｉ粉末を添加する方法では、Ｔｉ粉末の微細化には限界がある。そのため、相対的に高い触媒活性を得るためには、相対的に多量の触媒の添加が必要となる。 Next, the operation of the hydrogen storage material and the manufacturing method thereof according to the present invention will be described.
NaAlH 4 alone cannot reversibly occlude / release hydrogen, but reversibly occludes / releases hydrogen when a catalyst coexists. In this case, in order to obtain high catalytic activity, it is necessary to add a relatively large amount of catalyst or to refine the catalyst. However, as disclosed in Non-Patent Document 1, the method of adding Ti powder to a raw material mixture has a limit in the refinement of Ti powder. Therefore, in order to obtain a relatively high catalytic activity, it is necessary to add a relatively large amount of catalyst.

これに対し、ＮａＨとＡｌから固相反応によりＮａＡｌＨ4を合成する場合において、所定量のＦｅを不純物として含むＡｌを出発原料に用いると、Ｆｅを含む複合粒子が均一に分散した水素吸蔵材料が得られる。Ｆｅを含む複合粒子は、ＮａＡｌＨ4が水素を放出し、又は、ＮａＡｌＨ4の分解生成物が水素を再吸蔵する際に触媒として機能する。しかも、Ｆｅは、あらかじめ微粒子としてＡｌ中に含まれているので、粉砕混合条件を最適化することによって、複合粒子の粒径を容易に１０ｎｍ未満にすることができる。そのため、複合粒子の量が極めて少量であっても、高い触媒能を発揮する。また、有効水素量を低下させることなく、より低温での可逆的な水素の吸蔵／放出が可能となる。具体的には、１００〜１５０℃の低い温度と高圧水素により、３〜３．５ｗｔ％の水素を吸蔵／放出することが可能な水素吸蔵材料が得られる。しかも、原料であるＮａＨ及びＡｌは、ありふれた材料であるので、製造コストを低減することができる。 In contrast, in the case of synthesizing NaAlH 4 from NaH and Al by solid phase reaction, if Al containing a predetermined amount of Fe as an impurity is used as a starting material, a hydrogen storage material in which composite particles containing Fe are uniformly dispersed is obtained. can get. Composite particles containing Fe is, NaAlH 4 is release hydrogen, or degradation products of NaAlH 4 functions as a catalyst when re storing hydrogen. Moreover, since Fe is already contained in Al as fine particles, the particle size of the composite particles can be easily reduced to less than 10 nm by optimizing the pulverization and mixing conditions. Therefore, even if the amount of the composite particles is very small, high catalytic ability is exhibited. In addition, reversible hydrogen storage / release at a lower temperature is possible without reducing the effective hydrogen amount. Specifically, a hydrogen storage material capable of storing / releasing 3 to 3.5 wt% of hydrogen is obtained by a low temperature of 100 to 150 ° C. and high pressure hydrogen. Moreover, since the raw materials NaH and Al are common materials, manufacturing costs can be reduced.

（実施例１）
［１． 試料の作製］
ＮａＨ粉末（純度９５％、粒径１０〜５０μｍ、Ａｌｄｒｉｃｈ社製）及び純Ａｌ粉末（純度９９．９％、粒径５〜２０μｍ、レアメタリック社製）をモル比で１：１に配合した。表１に、使用したＮａＨ及び純Ａｌの分析値を示す。なお、表１には、市販のＡｌホイルの分析値も併せて示した。クロムモリブデン鋼（ＳＣＭ）の容器に高炭素クロム鋼（ＳＵＪ）のボール及び配合物を入れ、水素圧力１ＭＰａ、加速度６Ｇの条件下で５〜７２時間のメカニカルグラインディング（ＭＧ）処理を行った。 Example 1
[1. Preparation of sample]
NaH powder (purity 95%, particle size 10-50 μm, manufactured by Aldrich) and pure Al powder (purity 99.9%, particle size 5-20 μm, manufactured by Rare Metallic) were mixed at a molar ratio of 1: 1. Table 1 shows analytical values of NaH and pure Al used. Table 1 also shows analysis values of commercially available Al foil. A ball of a high carbon chromium steel (SUJ) and a compound were placed in a chromium molybdenum steel (SCM) container, and mechanical grinding (MG) treatment was performed for 5 to 72 hours under conditions of a hydrogen pressure of 1 MPa and an acceleration of 6G.

Figure 2007289877
Figure 2007289877

［２． 評価（１）：ＴＥＭ観察］
純Ａｌを用いて７２時間ＭＧ処理により得られた水素吸蔵材料について、ＴＥＭ観察を行った。図２（ａ）及び図２（ｂ）に、それぞれ、水素吸蔵材料の低倍率ＴＥＭ写真及び高倍率ＴＥＭ写真を示す。図２より、マトリックス中に、１０ｎｍ未満の黒い微細な粒子（複合粒子）が含まれていることがわかる。
次に、図２（ｂ）中、矢印で示した４箇所について、ＴＥＭにて組成分析を行った。図３に、その結果を示す。図３より、複合粒子には、Ｆｅ（６．４０、７．００ｋｅＶ）が含まれていることがわかった。 [2. Evaluation (1): TEM observation]
TEM observation was performed about the hydrogen storage material obtained by the MG process for 72 hours using pure Al. 2A and 2B show a low-magnification TEM photograph and a high-magnification TEM photograph of the hydrogen storage material, respectively. FIG. 2 shows that black fine particles (composite particles) of less than 10 nm are contained in the matrix.
Next, composition analysis was performed by TEM at four locations indicated by arrows in FIG. FIG. 3 shows the result. From FIG. 3, it was found that the composite particles contain Fe (6.40, 7.00 keV).

［３． 評価（２）：ラマンスペクトル］
純Ａｌを用いて２４時間ＭＧ処理により得られた水素吸蔵材料について、光学顕微鏡観察及びラマンスペクトルの測定を行った。図４に、その結果を示す。
光学顕微鏡により、黒い部位の中に数十μｍサイズの白い部位が多数析出しているのが観察された。ラマンスペクトルから、白い部位はＮａＡｌＨ4からなり、黒い部位は、非晶質なＮａＨ／Ａｌであることがわかった。
ＴＥＭ観察及びラマンスペクトルから、本発明に係る水素吸蔵材料の構造は、図１の概略図に示すような構造を持つことが確認された。 [3. Evaluation (2): Raman spectrum]
The hydrogen storage material obtained by MG treatment for 24 hours using pure Al was subjected to optical microscope observation and Raman spectrum measurement. FIG. 4 shows the result.
By the optical microscope, it was observed that many white parts having a size of several tens of μm were deposited in the black parts. From the Raman spectrum, it was found that the white part was composed of NaAlH 4 and the black part was amorphous NaH / Al.
From the TEM observation and the Raman spectrum, it was confirmed that the structure of the hydrogen storage material according to the present invention has a structure as shown in the schematic diagram of FIG.

［４． 評価（３）：水素吸蔵／放出特性］
純Ａｌを用いて５〜７２時間ＭＧ処理により得られた水素吸蔵材料について、温度１５０℃、水素圧６ＭＰａの条件下で水素を吸蔵させた。図５に、水素吸蔵時間と水素吸蔵量との関係を示す。図５より、ＭＧ処理時間が長くなるほど、短時間で多量の水素を吸蔵することがわかる。これは、長時間ＭＧ処理することにより、ＮａＨとＡｌの微細化が進行し、触媒である複合粒子の混合分散度が高まったためと考えられる。 [4. Evaluation (3): Hydrogen storage / release characteristics]
About the hydrogen storage material obtained by MG treatment for 5 to 72 hours using pure Al, hydrogen was stored under conditions of a temperature of 150 ° C. and a hydrogen pressure of 6 MPa. FIG. 5 shows the relationship between the hydrogen storage time and the hydrogen storage amount. FIG. 5 shows that a larger amount of hydrogen is stored in a shorter time as the MG treatment time is longer. This is thought to be due to the progress of the refinement of NaH and Al by the MG treatment for a long time, and the mixing and dispersion of the composite particles as the catalyst increased.

次に、純Ａｌを用いて７２時間ＭＧ処理により得られた水素吸蔵材料について、水素吸蔵量の水素圧力依存性を調べた。吸蔵温度は、１５０℃とした。図６に、その結果を示す。図６より、本発明に係る水素吸蔵材料は、水素吸蔵量の水素圧力依存性が顕著であり、吸蔵時の水素圧力が高くなるほど、水素吸着速度が大きくなることがわかる。
さらに、純Ａｌを用いて７２時間のＭＧ処理により得られた水素吸蔵材料について、水素吸蔵量の温度依存性を調べた。水素圧力は、６ＭＰａとした。図７に、その結果を示す。図７より、本発明に係る水素吸蔵材料は、６ＭＰａ、１５０℃、２４時間の条件で、３〜３．５％の水素を吸蔵できること、及び、温度を１００℃に低下させても、約３日で３〜３．５ｗｔ％の水素を吸蔵できることがわかる。 Next, the hydrogen pressure dependence of the hydrogen occlusion amount was investigated for the hydrogen occlusion material obtained by MG treatment for 72 hours using pure Al. The storage temperature was 150 ° C. FIG. 6 shows the result. FIG. 6 shows that the hydrogen storage material according to the present invention has a remarkable hydrogen pressure dependency of the hydrogen storage amount, and the higher the hydrogen pressure during storage, the higher the hydrogen adsorption rate.
Furthermore, the temperature dependence of the hydrogen storage amount was investigated about the hydrogen storage material obtained by MG processing for 72 hours using pure Al. The hydrogen pressure was 6 MPa. FIG. 7 shows the result. From FIG. 7, the hydrogen storage material according to the present invention can store 3 to 3.5% of hydrogen under conditions of 6 MPa, 150 ° C. and 24 hours, and even if the temperature is lowered to 100 ° C., it is about 3 It can be seen that 3 to 3.5 wt% of hydrogen can be occluded per day.

［５． 評価（４）：Ａｌの純度と水素吸蔵／放出特性との関係］
１０ｎｍ未満の複合粒子は、主にＦｅとＳｉ（データ省略）であることがＴＥＭによる分析から判断できる。その他、Ｆｅとして検出されるものの一部は、Ｆｅ3Ｃになっている可能性もあり、Ｃｒも微量存在する。水素吸蔵材料の触媒として機能すると考えられるＦｅをＩＣＰ（誘導結合プラズマ）発光分析すると、５時間ＭＧ処理と７２時間ＭＧ処理ではその量に大きな変化はなく、その量は、原料中のＡｌに含まれるＦｅ量とほぼ同等であった。すなわち、１０ｎｍ未満の複合粒子の約８０％は、Ａｌ中の不純物に起因すると考えられる。上述の結果は、純Ａｌの上限に近い素材を用いて得られた結果であるが、純Ａｌの下限に近い素材（純度９９％）を用いれば、Ｆｅ量を約１０〜２０倍増加させることができるので、水素吸蔵放出特性を大幅に改善できると考えられる。
この点を確認するために、表１に示す組成を有する家庭用アルミ箔（クッキングホイル、東洋アルミ製）を用いて、同様の実験を行った。その結果、ＭＧ処理時間：２４時間、水素吸蔵温度：１５０℃、水素圧：６ＭＰａの条件下では、約１０時間で１．５ｗｔ％の水素吸蔵量が得られ、水素吸蔵速度は、純Ａｌ粉末を用いた場合の約２倍であった。 [5. Evaluation (4): Relationship between Al purity and hydrogen storage / release characteristics]
It can be judged from the analysis by TEM that the composite particles of less than 10 nm are mainly Fe and Si (data omitted). In addition, part of what is detected as Fe may be Fe 3 C, and a small amount of Cr is also present. When ICP (inductively coupled plasma) emission analysis is performed on Fe, which is considered to function as a catalyst for hydrogen storage materials, there is no significant change in the amount between 5-hour MG treatment and 72-hour MG treatment, and the amount is contained in Al in the raw material. It was almost equivalent to the amount of Fe. That is, it is considered that about 80% of the composite particles of less than 10 nm are attributed to impurities in Al. The above results are obtained using a material close to the upper limit of pure Al. If a material close to the lower limit of pure Al (99% purity) is used, the amount of Fe is increased by about 10 to 20 times. Therefore, it is considered that the hydrogen storage / release characteristics can be greatly improved.
In order to confirm this point, a similar experiment was performed using household aluminum foil (cooking foil, manufactured by Toyo Aluminum) having the composition shown in Table 1. As a result, under the conditions of MG treatment time: 24 hours, hydrogen storage temperature: 150 ° C., hydrogen pressure: 6 MPa, a hydrogen storage amount of 1.5 wt% was obtained in about 10 hours, and the hydrogen storage rate was pure Al powder. It was about twice as much as when using.

（比較例１）
実施例１で用いたＮａＨ及びＡｌをモル比で１：１に配合し、乳鉢を用いて５分間混合した。得られた粉末について、温度：１５０℃、水素圧：６ＭＰａの条件下で水素と接触させた。しかしながら、２４時間経過後の水素吸蔵量は、ゼロであった。これは、軽度の粉砕混合を短時間行ったために、触媒となる複合粒子の微細化及び均一分散が不十分であるためと考えられる。 (Comparative Example 1)
NaH and Al used in Example 1 were mixed at a molar ratio of 1: 1, and mixed for 5 minutes using a mortar. The obtained powder was brought into contact with hydrogen under conditions of temperature: 150 ° C. and hydrogen pressure: 6 MPa. However, the hydrogen storage amount after the lapse of 24 hours was zero. This is presumably because fine pulverization and mixing were performed for a short time, so that the fine particles and uniform dispersion of the composite particles serving as a catalyst were insufficient.

（比較例２、３）
［１． 試料の作製］
ＬｉＨ粉末（粒径１０〜５０μｍ、Ａｌｄｒｉｃｈ社製）及び純Ａｌ粉末（表１に示す純度９９．９％Ａｌ、レアメタリック社製）をモル比で１：１に配合した。クロムモリブデン鋼（ＳＣＭ）の容器に高炭素クロム鋼（ＳＵＪ）のボール及び配合物を入れ、水素圧力１ＭＰａ、加速度６Ｇの条件下で６５時間のＭＧ処理を行った（比較例２）。
また、ＬｉＨ粉末（粒径１〜５０μｍ、Ａｌｄｒｉｃｈ社製）及び純Ａｌ粉末（表１に示す純度９９．９％Ａｌ、レアメタリック社製）をモル比で１：１に配合し、これにさらに５ｗｔ％のＴｉＣｌ3粉末を加えた。クロムモリブデン鋼（ＳＣＭ）の容器に高炭素クロム鋼（ＳＵＪ）のボール及び配合物を入れ、水素圧力１ＭＰａ、加速度６Ｇの条件下で７０時間のＭＧ処理を行った（比較例３）。
さらに、得られた試料（比較例２、３）について、温度１７０℃、水素圧７０ＭＰａ、処理時間１６８時間（１ｗ）の条件下で水素と接触させる処理（高圧処理）を行った。 (Comparative Examples 2 and 3)
[1. Preparation of sample]
LiH powder (particle size: 10-50 μm, manufactured by Aldrich) and pure Al powder (purity: 99.9% Al shown in Table 1; manufactured by Rare Metallic) were mixed at a molar ratio of 1: 1. A ball of a high carbon chromium steel (SUJ) and a compound were placed in a chromium molybdenum steel (SCM) container, and MG treatment was performed for 65 hours under conditions of a hydrogen pressure of 1 MPa and an acceleration of 6 G (Comparative Example 2).
Further, LiH powder (particle size: 1-50 μm, manufactured by Aldrich) and pure Al powder (purity: 99.9% Al shown in Table 1; manufactured by Rare Metallic) were mixed at a molar ratio of 1: 1, and further 5 wt% TiCl 3 powder was added. A ball of a high carbon chromium steel (SUJ) and a compound were placed in a chromium molybdenum steel (SCM) container and subjected to MG treatment for 70 hours under conditions of a hydrogen pressure of 1 MPa and an acceleration of 6 G (Comparative Example 3).
Further, the obtained samples (Comparative Examples 2 and 3) were subjected to a treatment (high pressure treatment) for contacting with hydrogen under the conditions of a temperature of 170 ° C., a hydrogen pressure of 70 MPa, and a treatment time of 168 hours (1 w).

［２． 評価（１）：Ｘ線回折］
図８に、比較例２で得られた高圧処理後の試料のＸ線回折パターンを示す。Ｘ線回折では、ＬｉＡｌＨ4の確認は難しいが、ラマンスペクトル（図示せず）からＬｉＡｌＨ4の生成を確認した。 [2. Evaluation (1): X-ray diffraction]
FIG. 8 shows an X-ray diffraction pattern of the sample after the high-pressure treatment obtained in Comparative Example 2. Although it was difficult to confirm LiAlH 4 by X-ray diffraction, the production of LiAlH 4 was confirmed from a Raman spectrum (not shown).

［３． 評価（２）：水素放出特性］
図９（ａ）に、比較例２で得られた試料の水素ＭＧ処理後の水素放出量、及び水素ＭＧ処理＋高圧処理後の水素放出量を示し、図９（ｂ）に、同試料の水素放出速度を示す。また、図９（ｃ）に、比較例３で得られた試料の水素ＭＧ処理後の水素放出量、及び水素ＭＧ処理＋高圧処理後の水素放出量を示し、図９（ｄ）に、同試料の水素放出速度を示す。
図９より、
（１）触媒を添加しない試料（比較例２）の場合、高圧処理の有無にかかわらず、３００℃での水素放出量は、わずか０．２５ｗｔ％であること、及び、
（２）触媒を添加した試料（比較例３）の場合、３００℃での水素放出量は、高圧処理を行わないときは０．３５ｗｔ％、高圧処理を行ったときは０．５ｗｔ％であること、
がわかる。
この結果は、ＬｉＨ／Ａｌの混合物にＴｉＣｌ3を添加して粉砕混合しても、水素放出温度は低下せず、かつ、可逆的な水素の吸蔵／放出がほとんどできないこと（すなわち、添加したＴｉＣｌ3がほとんど触媒として機能していないこと）を示している。 [3. Evaluation (2): Hydrogen Release Characteristics]
FIG. 9A shows the hydrogen release amount after the hydrogen MG treatment of the sample obtained in Comparative Example 2, and the hydrogen release amount after the hydrogen MG treatment + high pressure treatment, and FIG. The hydrogen release rate is shown. Further, FIG. 9C shows the hydrogen release amount after the hydrogen MG treatment of the sample obtained in Comparative Example 3, and the hydrogen release amount after the hydrogen MG treatment + high pressure treatment, and FIG. The hydrogen release rate of the sample is shown.
From FIG.
(1) In the case of a sample to which no catalyst is added (Comparative Example 2), the hydrogen release amount at 300 ° C. is only 0.25 wt% regardless of the presence or absence of high-pressure treatment, and
(2) In the case of the sample to which the catalyst is added (Comparative Example 3), the hydrogen release amount at 300 ° C. is 0.35 wt% when the high pressure treatment is not performed and 0.5 wt% when the high pressure treatment is performed. thing,
I understand.
This result shows that even when TiCl 3 is added to the LiH / Al mixture and pulverized and mixed, the hydrogen release temperature does not decrease and reversible hydrogen absorption / release is hardly possible (ie, the added TiCl 3 is hardly functioning as a catalyst).

以上、本発明の実施の形態について詳細に説明したが、本発明は上記実施の形態に何ら限定されるものではなく、本発明の要旨を逸脱しない範囲内で種々の改変が可能である。   Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

本発明に係る水素吸蔵材料及び水素化物複合体は、燃料電池システム用の水素貯蔵手段、超高純度水素製造装置、ケミカル式ヒートポンプ、アクチュエータ、金属−水素蓄電池用の水素貯蔵体等に用いることができる。   The hydrogen storage material and hydride composite according to the present invention can be used for hydrogen storage means for fuel cell systems, ultra-high purity hydrogen production equipment, chemical heat pumps, actuators, hydrogen storage bodies for metal-hydrogen storage batteries, and the like. it can.

本発明に係る水素吸蔵材料の微構造を示す概略図である。It is the schematic which shows the microstructure of the hydrogen storage material which concerns on this invention. 図２（ａ）及び図２（ｂ）は、それぞれ、純Ａｌを用いて７２時間ＭＧ処理により得られた水素吸蔵材料の低倍率ＴＥＭ写真、及び高倍率ＴＥＭ写真である。FIGS. 2A and 2B are a low-magnification TEM photograph and a high-magnification TEM photograph of the hydrogen storage material obtained by MG treatment for 72 hours using pure Al, respectively. 図３（ａ）〜図３（ｄ）は、それぞれ、図２（ｂ）に矢印で示した領域について測定された元素分析結果である。FIGS. 3A to 3D are elemental analysis results measured for the regions indicated by arrows in FIG. 純Ａｌを用いて２４時間のＭＧ処理により得られた水素吸蔵材料の光学顕微鏡写真、並びに、白い部位及び黒い部位のラマンスペクトルである。It is the optical microscope photograph of the hydrogen storage material obtained by the MG process for 24 hours using pure Al, and the Raman spectrum of a white site | part and a black site | part. ＭＧ処理時間の異なる水素吸蔵材料に対し、温度１５０℃、水素圧力６ＭＰａの条件で水素を吸蔵させたときの時間と水素吸蔵量との関係を示す図である。It is a figure which shows the relationship between the time and hydrogen storage amount when hydrogen is occluded on the conditions of temperature 150 degreeC and hydrogen pressure 6MPa with respect to the hydrogen storage material from which MG processing time differs. 純Ａｌを用いて７２時間のＭＧ処理により得られた水素吸蔵材料に対し、温度１５０℃、水素圧力３〜９ＭＰａの条件で水素を吸蔵させたときの時間と水素吸蔵量との関係を示す図である。The figure which shows the relationship between the time when hydrogen is occluded on the conditions of temperature 150 degreeC and hydrogen pressure 3-9MPa, and the hydrogen occlusion amount with respect to the hydrogen occlusion material obtained by the MG process for 72 hours using pure Al. It is. 純Ａｌを用いて７２時間のＭＧ処理により得られた水素吸蔵材料に対し、温度１００〜１５０℃、水素圧力６ＭＰａの条件で水素を吸蔵させたときの時間と水素吸蔵量との関係を示す図である。The figure which shows the relationship between the time when hydrogen is occluded on the conditions of temperature 100-150 degreeC and hydrogen pressure 6MPa, and the hydrogen occlusion amount with respect to the hydrogen occlusion material obtained by the MG process for 72 hours using pure Al. It is. ＬｉＨ／Ａｌに対し、水素ＭＧ処理及び高圧処理をした後のＸ線回折パターンである。It is an X-ray-diffraction pattern after carrying out hydrogen MG process and a high voltage | pressure process with respect to LiH / Al. 図９（ａ）は、ＬｉＨ／Ａｌに対し、水素ＭＧ処理のみ又は水素ＭＧ処理＋高圧処理をした後の水素放出量であり、図９（ｂ）は、同試料の水素放出速度である。また、図９（ｃ）は、（ＬｉＨ／Ａｌ）／５ｗｔ％ＴｉＣｌ3に対し、水素ＭＧ処理のみ又は水素ＭＧ処理＋高圧処理をした後の水素放出量であり、図９（ｄ）は、同試料の水素放出速度である。FIG. 9A shows the hydrogen release amount after performing only the hydrogen MG treatment or hydrogen MG treatment + high pressure treatment on LiH / Al, and FIG. 9B shows the hydrogen release rate of the same sample. FIG. 9C shows the hydrogen release amount after performing only the hydrogen MG treatment or hydrogen MG treatment + high pressure treatment on (LiH / Al) / 5 wt% TiCl 3 , and FIG. This is the hydrogen release rate of the sample.

Claims (7)

ＮａＨと、０．０５ｍａｓｓ％以上２．０ｍａｓｓ％以下のＦｅを含むＡｌとを配合する配合工程と、
前記配合工程で得られた配合物を非酸化雰囲気下において粉砕混合する粉砕混合工程を備え、
前記粉砕混合工程は、Ｆｅを含む複合粒子の粒径が１０ｎｍ未満となるように、前記粉砕混合を行うものである水素吸蔵材料の製造方法。 A blending step of blending NaH and Al containing 0.05 mass% or more and 2.0 mass% or less of Fe;
Comprising a pulverizing and mixing step of pulverizing and mixing the compound obtained in the compounding step in a non-oxidizing atmosphere;
The pulverization and mixing step is a method for producing a hydrogen storage material, wherein the pulverization and mixing is performed so that the particle size of the composite particles containing Fe is less than 10 nm. 前記粉砕混合工程は、水素雰囲気下において前記粉砕混合を行うものである請求項１に記載の水素吸蔵材料の製造方法。   The method for producing a hydrogen storage material according to claim 1, wherein the pulverizing and mixing step is performed by performing the pulverizing and mixing in a hydrogen atmosphere. 請求項１又は２に記載の方法により得られる水素吸蔵材料。   A hydrogen storage material obtained by the method according to claim 1. ＮａＨと、Ａｌと、ＮａＡｌＨ4との混合物からなるマトリックスと、
前記マトリックス中に分散しているＦｅを含む複合粒子とを備え、
前記複合粒子の粒径は、１０ｎｍ未満である水素吸蔵材料。 A matrix composed of a mixture of NaH, Al and NaAlH 4 ;
Comprising composite particles containing Fe dispersed in the matrix,
A hydrogen storage material, wherein the composite particles have a particle size of less than 10 nm. 前記複合粒子の量は、０．００１モル％以上０．１モル％未満である請求項４に記載の水素吸蔵材料。   The hydrogen storage material according to claim 4, wherein the amount of the composite particles is 0.001 mol% or more and less than 0.1 mol%. 請求項３から５までのいずれかに記載の水素吸蔵材料に水素を吸蔵させることにより得られる水素化物複合体。   A hydride composite obtained by storing hydrogen in the hydrogen storage material according to any one of claims 3 to 5. 請求項６に記載の水素化物複合体から水素の全部又は一部を放出させることにより得られる水素吸蔵材料。
A hydrogen storage material obtained by releasing all or part of hydrogen from the hydride composite according to claim 6.
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