JP2007302487A - Hydrogen occlusion material and its production method - Google Patents
Hydrogen occlusion material and its production method Download PDFInfo
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 328
- 239000001257 hydrogen Substances 0.000 title claims abstract description 321
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 321
- 239000000463 material Substances 0.000 title claims abstract description 73
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 238000003860 storage Methods 0.000 claims abstract description 143
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- 229910045601 alloy Inorganic materials 0.000 claims abstract description 83
- 229910052751 metal Inorganic materials 0.000 claims abstract description 54
- 239000002184 metal Substances 0.000 claims abstract description 54
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 40
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 40
- 239000011232 storage material Substances 0.000 claims description 60
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 38
- 238000000034 method Methods 0.000 claims description 32
- 239000002245 particle Substances 0.000 claims description 22
- 229910002804 graphite Inorganic materials 0.000 claims description 16
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- 238000002156 mixing Methods 0.000 claims description 10
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 8
- 229910052700 potassium Inorganic materials 0.000 claims description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 7
- 239000011812 mixed powder Substances 0.000 claims description 7
- 238000001704 evaporation Methods 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 238000007740 vapor deposition Methods 0.000 claims description 5
- 229910000861 Mg alloy Inorganic materials 0.000 claims description 4
- RZJQYRCNDBMIAG-UHFFFAOYSA-N [Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Zn].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn] Chemical class [Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Cu].[Zn].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Ag].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn].[Sn] RZJQYRCNDBMIAG-UHFFFAOYSA-N 0.000 claims description 4
- 230000006835 compression Effects 0.000 claims description 4
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- 229910001068 laves phase Inorganic materials 0.000 claims description 4
- 229910002593 Fe-Ti Inorganic materials 0.000 claims description 3
- 229910020794 La-Ni Inorganic materials 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 230000008020 evaporation Effects 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052746 lanthanum Inorganic materials 0.000 claims description 3
- 229910052744 lithium Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052706 scandium Inorganic materials 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 229910052712 strontium Inorganic materials 0.000 claims description 3
- 229910052727 yttrium Inorganic materials 0.000 claims description 3
- 229910052726 zirconium Inorganic materials 0.000 claims description 3
- 238000005245 sintering Methods 0.000 claims 1
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- 238000010521 absorption reaction Methods 0.000 description 77
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 5
- 238000001994 activation Methods 0.000 description 5
- 239000002041 carbon nanotube Substances 0.000 description 5
- 229910021393 carbon nanotube Inorganic materials 0.000 description 5
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- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
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- 238000010907 mechanical stirring Methods 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
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Classifications
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/32—Hydrogen storage
Abstract
Description
本発明は、水素ガスの吸蔵材料及び該吸蔵材料を有する水素ガスの貯蔵容器、並びに該水素吸蔵材料の製造方法に関する。 The present invention relates to a hydrogen gas storage material, a hydrogen gas storage container having the storage material, and a method for producing the hydrogen storage material.
水素吸蔵材料は、比較的低温または高圧雰囲気において水素を吸蔵して発熱を伴って金属水素化物を生成し、一方、比較的高温または低圧雰囲気において水素ガスを放出する。
このような水素吸蔵材料は、水素貯蔵用に利用が図られる。
これまで開発されている水素ガスの貯蔵方法は、（ｉ）高圧ガスとしての貯蔵方法、（ii）水素ガスの液化貯蔵方法、及び（iii）水素ガスを合金材料等に吸蔵させる方法、の三つに分類することができる。
しかしながら、前記三つの従来技術にはそれぞれ問題点が存在する。（ｉ）の貯蔵方法は、ボンベのような金属製の耐圧容器を使用する必要があり、この容器の重量が非常に重い。またその蓄積密度がせいぜい１２ｍｇ／ｍｌ程度と低く、更に高圧であるために安全面での配慮が必要である。
前記（ii）の方法は、水素ガスをいったん液化して蓄えるもので、液化水素の蓄積密度は約７０ｍｇ／ｍｌ程度と相対的には高い蓄積密度である。しかし、水素ガスの液化は、約−２５０℃以下の定温で行う必要があるために冷却装置の付加と、冷却エネルギー消費を伴う問題点がある。
The hydrogen storage material stores hydrogen in a relatively low temperature or high pressure atmosphere to generate a metal hydride with heat generation, while releasing hydrogen gas in a relatively high temperature or low pressure atmosphere.
Such a hydrogen storage material can be used for hydrogen storage.
The hydrogen gas storage methods that have been developed so far are (i) a storage method as high-pressure gas, (ii) a liquefied storage method for hydrogen gas, and (iii) a method for storing hydrogen gas in an alloy material or the like. Can be classified.
However, each of the three conventional techniques has problems. The storage method (i) requires the use of a metal pressure vessel such as a cylinder, and the weight of this vessel is very heavy. In addition, the accumulated density is as low as about 12 mg / ml and the pressure is higher, so safety considerations are necessary.
In the method (ii), hydrogen gas is temporarily liquefied and stored, and the accumulation density of liquefied hydrogen is a relatively high accumulation density of about 70 mg / ml. However, since the liquefaction of hydrogen gas needs to be performed at a constant temperature of about −250 ° C. or less, there are problems associated with the addition of a cooling device and the consumption of cooling energy.
前記（iii）の方法は、水素吸蔵合金等の水素吸蔵材料を用いるもので、その貯蔵密度は、合金等への吸蔵であるにもかかわらず高く、液体水素の密度以上である。また、水素の吸蔵と放出が室温付近で可能であり、取り扱いが比較的容易である。
また何らかのトラブルで水素吸蔵容器の内圧の急上昇が起こったときに、水素吸蔵体が水素を吸蔵することにより水素吸蔵容器内の内圧上昇を抑え、その間にトラブルが解決すれば容器内の水素を外部に放出せずにすみ、容器の安全性を高めることができる。
そこで近年、第三の水素貯蔵方法として水素を金属材料に貯蔵させる方法が試みられている。この方法を採用することにより大きな貯蔵密度を実現できるとともに、水素貯蔵容器の重量の軽減が図れ、また特殊な水素貯蔵条件も必要とせず、水素ガス漏れや液化水素ガスの気化に対する安全性の点からも優れた効果が期待できる（特許文献１）。
The method (iii) uses a hydrogen storage material such as a hydrogen storage alloy, and its storage density is high despite being stored in the alloy or the like, and is higher than the density of liquid hydrogen. In addition, hydrogen can be stored and released near room temperature, and handling is relatively easy.
Also, when the internal pressure of the hydrogen storage container suddenly increases due to some trouble, the hydrogen storage body stores the hydrogen to suppress the internal pressure increase in the hydrogen storage container. Therefore, it is possible to increase the safety of the container.
Therefore, in recent years, a method of storing hydrogen in a metal material has been tried as a third hydrogen storage method. By adopting this method, a large storage density can be realized, the weight of the hydrogen storage container can be reduced, and there is no need for special hydrogen storage conditions, which is a point of safety against hydrogen gas leakage and liquefied hydrogen gas vaporization. Therefore, an excellent effect can be expected (Patent Document 1).
現在、水素ガスを吸蔵させるために実用化が検討されている金属材料はいくつかあるが、その中でも水素吸蔵合金（例えばＭｇ２Ｎｉ合金）とナノカーボン材からなる複合体は、水素貯蔵量が３．６質量％程度と高く、質量当りの水素貯蔵密度の点から優れており、次世代の水素吸蔵材料として注目されている。しかしながら、この水素吸蔵体は、水素吸収速度が遅く、そのままでは実用レベルに達していないという問題がある。車載用途あるいはモバイル用途の燃料として用いるためには、最大水素吸蔵量の８０％に到達するまでの時間が５分以内であることが必須要件であると考えられるが、この水素吸蔵体では、最大水素貯蔵量の８０％に到達するまでに４０分程度も必要であった。前記水素吸収速度を早くするために他の金属や合金を添加する方法も考えられるが、他の金属や合金を混ぜると水素吸蔵体としての水素吸蔵量が減少するので好ましくない。一方、水素吸収速度が早い合金（例えばＬａＮｉ５合金）では、水素吸蔵量が１．６重量％程度に低下するので、実用レベルには達していない。
従って、これまで、水素吸蔵量と水素吸収速度の双方について共に実用性レベルを満たす水素吸蔵材料は見出されていない。
Currently, there are several metal materials that are being put into practical use in order to occlude hydrogen gas. Among them, composites composed of hydrogen occlusion alloys (for example, Mg 2 Ni alloys) and nanocarbon materials have a hydrogen storage capacity. It is as high as about 3.6% by mass and is excellent in terms of hydrogen storage density per mass, and is attracting attention as a next-generation hydrogen storage material. However, this hydrogen occlusion body has a problem that the hydrogen absorption rate is slow and it does not reach a practical level as it is. In order to use it as a fuel for in-vehicle or mobile applications, it is considered that the time required to reach 80% of the maximum hydrogen storage amount is 5 minutes or less. It took about 40 minutes to reach 80% of the hydrogen storage amount. In order to increase the hydrogen absorption rate, a method of adding another metal or alloy is conceivable. However, mixing other metal or alloy is not preferable because the hydrogen storage amount as a hydrogen storage body is reduced. On the other hand, an alloy having a high hydrogen absorption rate (for example, LaNi 5 alloy) does not reach a practical level because the hydrogen storage amount is reduced to about 1.6% by weight.
Therefore, until now, no hydrogen storage material satisfying the practical level of both the hydrogen storage amount and the hydrogen absorption rate has been found.
本発明はこのような状況に鑑みてなされたもので、水素吸蔵合金粉末とナノカーボン材からなる複合体について、高い水素吸蔵量を維持して、従来の問題点である水素吸収速度を改良して、実用性レベルを満たす水素吸蔵材料を提供することを目的とする。 The present invention has been made in view of such a situation, and for a composite composed of a hydrogen storage alloy powder and a nanocarbon material, a high hydrogen storage amount is maintained and the conventional hydrogen absorption rate is improved. An object of the present invention is to provide a hydrogen storage material that satisfies a practical level.
本発明者らは、水素吸蔵合金粉末とアルカリ金属でドープされたナノカーボン材からなる複合体を使用することにより、上記課題が解決できることを見出し、本発明を完成させた。
すなわち、本発明の第１の態様は、（１）少なくともアルカリ金属がドープされたナノカーボン材、並びに水素吸蔵金属及び／又は合金からなり、かつ該水素吸蔵金属及び／又は合金と、該ナノカーボン材により形成される空隙を有する複合体であることを特徴とする水素吸蔵材料に関する発明である。
The present inventors have found that the above problems can be solved by using a composite composed of a hydrogen storage alloy powder and a nanocarbon material doped with an alkali metal, and completed the present invention.
That is, the first aspect of the present invention includes (1) a nanocarbon material doped with at least an alkali metal, and a hydrogen storage metal and / or alloy, and the hydrogen storage metal and / or alloy and the nanocarbon. The present invention relates to a hydrogen storage material, which is a composite having voids formed of a material.
第１の態様においては、さらに下記（２）ないし（１０）の態様とすることができる。
（２）前記ナノカーボン材が、単層カーボンナノチューブ、多層カーボンナノチューブ、及びカーボンナノホーンから選択された１種又は２種以上からなること、
（３）前記水素吸蔵金属及び／又は合金が、Ｍｇ、Ｃａ、Ｓｒ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｙ、Ｚｒ、Ｎｂ、Ｐｄ、Ａｇ及びＬａから選択された１種又は２種以上を含むこと、
（４）前記水素吸蔵合金が、Ｌａ−Ｎｉ系合金、ＭＭ−Ｎｉ系合金、II族元素−Ｎｉ系合金、Ｍｇ合金、Ｆｅ−Ｔｉ系合金、ラベス相合金及びＢＣＣ合金のいずれかであること、
（５）前記水素吸蔵金属及び／又は合金の平均粒径が５０μｍ以下であること、
（６）前記アルカリ金属がＬｉ、Ｎａ及びＫから選択された１種又は２種以上からなること、
（７）前記アルカリ金属がドープされてナノカーボン材のグラファイト層間又はグラファイト束の隙間に分散して存在していること、
（８）前記水素吸蔵材料中において、ナノカーボン材が水素吸蔵金属及び／又は合金１００質量部に対して、０．１〜１０質量部含有されていること、
（９）前記水素吸蔵材料中において、前記アルカリ金属がナノカーボン材１００質量部に対して、１〜５０質量部含有されていること、
In the first aspect, the following aspects (2) to (10) can be further provided.
(2) The nanocarbon material is composed of one or more selected from single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanohorns,
(3) The hydrogen storage metal and / or alloy is selected from Mg, Ca, Sr, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Pd, Ag, and La Including one or two or more
(4) The hydrogen storage alloy is any one of La—Ni alloy, MM—Ni alloy, Group II element—Ni alloy, Mg alloy, Fe—Ti alloy, Laves phase alloy, and BCC alloy. ,
(5) The hydrogen storage metal and / or alloy has an average particle size of 50 μm or less,
(6) The alkali metal is composed of one or more selected from Li, Na and K,
(7) The alkali metal is doped and exists dispersed in the graphite layers of the nanocarbon material or in the gaps between the graphite bundles,
(8) In the hydrogen storage material, the nanocarbon material is contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the hydrogen storage metal and / or alloy,
(9) In the hydrogen storage material, the alkali metal is contained in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the nanocarbon material.
本発明の第２の態様は、（１０）前記（１）ないし（９）のいずれかに記載の水素吸蔵材料を有する水素吸蔵手段、熱制御手段及び圧力制御手段を備えた水素貯蔵容器に関する発明である。 A second aspect of the present invention is (10) an invention relating to a hydrogen storage container provided with a hydrogen storage means, a heat control means, and a pressure control means having the hydrogen storage material according to any one of (1) to (9). It is.
本発明の第３の態様は、（１１）アルカリ金属がドープされたナノカーボン材料と、水素吸蔵金属及び／又は合金とを有機溶媒中で混合した後に該有機溶媒を蒸発除去し、得られた混合粉末を金型内で圧縮成形し、その後不活性ガス雰囲気下で焼結することを特徴とする水素吸蔵材料の製造方法に関する発明である。
上記第３の態様において、（１２）アルカリ金属によるナノカーボン材料のドープを蒸着法により行うことができる。
The third aspect of the present invention was obtained by (11) mixing an alkali metal-doped nanocarbon material and a hydrogen storage metal and / or alloy in an organic solvent and then evaporating and removing the organic solvent. The invention relates to a method for producing a hydrogen storage material, wherein the mixed powder is compression molded in a mold and then sintered in an inert gas atmosphere.
In the third aspect, (12) the nanocarbon material can be doped with an alkali metal by a vapor deposition method.
本発明は、アルカリ金属がドープされたナノカーボン材料と水素吸蔵金属及び／又は合金（以下、「水素吸蔵金属及び／又は合金」を水素吸蔵金属等ということがある。）を含有する複合体とすることにより、ナノカーボン材料が水素吸蔵金属等の間に位置して、隣り合う水素吸蔵金属等同士の接触による内部応力の増加を抑制すると共に水素吸蔵による膨張の緩衝材として作用して、粉化による水素吸蔵材料の劣化を防止する。また水素吸蔵物間に位置するナノカーボン材料が水素吸蔵空間を確保すると共に水素吸収速度の向上効果をもたらし、更にナノカーボン材料がアルカリ金属でドープされていることにより、水素の吸蔵を一層促進する作用を奏し、これらのことから水素吸収速度が大幅に増加される。 The present invention includes a composite containing a nanocarbon material doped with an alkali metal and a hydrogen storage metal and / or alloy (hereinafter, “hydrogen storage metal and / or alloy” may be referred to as a hydrogen storage metal or the like). As a result, the nanocarbon material is located between the hydrogen storage metals, etc., and suppresses an increase in internal stress due to contact between adjacent hydrogen storage metals, etc., and acts as a buffer for expansion due to hydrogen storage. Prevents deterioration of hydrogen storage materials due to chemical conversion. The nanocarbon material located between the hydrogen occlusions secures the hydrogen occlusion space and improves the hydrogen absorption rate. Further, the nanocarbon material is doped with an alkali metal to further promote hydrogen occlusion. There is an effect, and from these, the hydrogen absorption rate is greatly increased.
[１] 第１の態様
本発明の第１の態様に係る水素吸蔵材料は、少なくともアルカリ金属でドープされたナノカーボン材、並びに水素吸蔵金属及び／又は合金からなり、かつ少なくとも該水素吸蔵金属及び／又は合金とこれらの間に位置する該ナノカーボン材により形成される空隙を有する複合体であることを特徴とする。
以下、[イ]〜[ハ]に第１の態様に係る水素吸蔵材料について詳述する。
[1] First Aspect The hydrogen storage material according to the first aspect of the present invention comprises at least a nanocarbon material doped with an alkali metal, and a hydrogen storage metal and / or alloy, and at least the hydrogen storage metal and It is a composite having voids formed by the nanocarbon material located between the alloy and the alloy.
Hereinafter, the hydrogen storage material according to the first embodiment will be described in detail in [i] to [c].
[イ] 水素吸蔵金属及び／又は合金
本発明に使用する水素吸蔵金属及び／又は合金は、Ｍｇ、Ｃａ、Ｓｒ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｙ、Ｚｒ、Ｎｂ、Ｐｄ、Ａｇ及びＬａから選択された１種又は２種以上を含むことが好ましい。これらの中でも特にＭｇ、Ｔｉ、Ｖは、軽量であることから特に好ましく、複数種類の金属または合金を含む場合においても少なくとも、Ｍｇ、Ｔｉ、Ｖのうちの少なくとも１種類を同時に含むことが好ましい。
また、水素吸蔵合金には、Ｌａ−Ｎｉ系合金、ＭＭ−Ｎｉ系合金、II族元素−Ｎｉ系合金、Ｍｇ合金、Ｆｅ−Ｔｉ系合金、ラベス相合金、ＢＣＣ合金などが用いられる。
上記ＭＭ−Ｎｉ系合金とは、ＬａＮｉ５において高価なＬａの代わりにミッシュメタルと呼ばれるＬａを含む合金を使用した合金である。ラベス（Ｌａｖｅｓ）相合金とは、合金を結晶構造で定義したもので、例えばＭｇ２Ｎｉが代表的な該合金の結晶構造である。
ＢＣＣ合金とは、その結晶構造が体心立方格子構造である合金の一般的な略称である。体心立方格子構造とは単位格子の四隅と中心に原子が位置する構造（body-centered cubic lattice）で、ＢＣＣ合金とは前記英語標記の略である。
前記合金を使用することにより、水素吸蔵の温度・圧力条件と放出の温度・圧力条件が比較的近似するという効果を得ることができる。
尚、Ｍｇ合金、ＢＣＣ合金は質量当りの水素貯蔵密度が高いことから特に好ましい。
[I] Hydrogen storage metal and / or alloy The hydrogen storage metal and / or alloy used in the present invention includes Mg, Ca, Sr, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, It is preferable to include one or more selected from Zr, Nb, Pd, Ag, and La. Among these, Mg, Ti, and V are particularly preferable because they are lightweight, and it is preferable that at least one of Mg, Ti, and V is included at the same time even when a plurality of types of metals or alloys are included.
As the hydrogen storage alloy, a La—Ni alloy, a MM—Ni alloy, a Group II element—Ni alloy, a Mg alloy, a Fe—Ti alloy, a Laves phase alloy, a BCC alloy, or the like is used.
The MM-Ni alloy is an alloy using an alloy containing La called Misch metal instead of expensive La in LaNi 5 . The Laves phase alloy is an alloy that is defined by a crystal structure. For example, Mg 2 Ni is a typical crystal structure of the alloy.
A BCC alloy is a general abbreviation for an alloy whose crystal structure is a body-centered cubic lattice structure. The body-centered cubic lattice structure is a structure in which atoms are located at the four corners and the center of the unit cell (body-centered cubic lattice), and BCC alloy is an abbreviation for the above-mentioned English mark.
By using the alloy, it is possible to obtain an effect that the temperature / pressure conditions for hydrogen storage and the temperature / pressure conditions for release are relatively approximate.
Mg alloys and BCC alloys are particularly preferable because of high hydrogen storage density per mass.
上記水素吸蔵金属及び／又は合金（水素吸蔵金属等）としては、水素化物を形成する金属が好ましく使用される。
これらの水素吸蔵金属等は、微細化されていることが望ましく、これによって上記の可逆的な水素の吸蔵と脱離のより一層の低温動作化を図ることができ、またナノカーボン材と混合して水素吸蔵材料の前駆体である複合体が形成されるので、ナノカーボン材との均一混合性を考慮すると粉末形状のものが好ましい。これらのことから、水素吸蔵金属等の平均粒径は、５０μｍ以下であることが好ましく、１０μｍ以下であることが特に好ましい。平均粒径の下限範囲は特に制限を受けるものではないが、商業的に作製可能な粒径を考慮すると、１μｍ程度以上が実用的である。
なお、前記微細化の手段としては、機械的攪拌等などが挙げられる。また、前記平均粒径は、レーザ回折式粒度分布測定装置を用いて測定することができる。
As said hydrogen storage metal and / or alloy (hydrogen storage metal etc.), the metal which forms a hydride is used preferably.
These hydrogen storage metals and the like are desirably miniaturized, thereby enabling the above-described reversible hydrogen storage and desorption to be performed at a lower temperature, and mixing with nanocarbon materials. Thus, a composite that is a precursor of the hydrogen storage material is formed. Therefore, in consideration of uniform mixing with the nanocarbon material, a powder form is preferable. For these reasons, the average particle size of the hydrogen storage metal or the like is preferably 50 μm or less, and particularly preferably 10 μm or less. The lower limit of the average particle diameter is not particularly limited, but considering a commercially available particle diameter, about 1 μm or more is practical.
Examples of the means for miniaturization include mechanical stirring. The average particle diameter can be measured using a laser diffraction particle size distribution measuring apparatus.
[ロ] ナノカーボン材
本発明におけるナノカーボンとは、ナノメートル（１０のマイナス９乗メートル）サイズの炭素のみで構造される物質の総称で、その構造は図１（ａ）に示すように、１つの層からなるチューブ形状の単層カーボンナノチューブ（以下ＳＷＣＮＴと略す）、図１（ｂ）に示す２つの層からなる２層カーボンナノチューブ（以下ＤＷＣＮＴと略す）、図１（ｃ）に示す３層以上の多層構造を有する多層カーボンナノチューブ（以下ＭＷＣＮＴと略す）、図１（ｅ）に示すカップスタック状カーボンナノチューブ（以下ＣＳＣＮＴと略す）等がある。一方、図１（ｄ）に示す気相成長炭素繊維（以下ＶＧＣＦと略す）や、図１（ｆ）に示すカーボンナノホーン（以下ＣＮＨと略す）、及びカーボンナノファイバーなどの種類もある。
前記ナノカーボン材として、単層カーボンナノチューブ、多層カーボンナノチューブの少なくとも一方を含むことによってアルカリ金属がドープできる構造を持ち、キャリア密度を向上させることができるという効果を得ることができる。
なお、多層カーボンナノチューブを用いる場合には、グラファイト間を押し広げ易く、多くのアルカリ金属がドープできる点から好ましくは２５層以下、さらに好ましくは１０層以下の総数を有する。
これらのナノカーボン材は、アーク放電法、化学的気相合成法（ＤＶＤ法）、アーク放電法、レーザーアブレーション法、炭化水素触媒合成法、シリコンカーバイト（ＳｉＣ）高温処理法などで作製される。
[B] Nanocarbon material Nanocarbon in the present invention is a general term for substances composed only of nanometer (10 to the ninth power) carbon size, and its structure is shown in FIG. A tube-shaped single-walled carbon nanotube (hereinafter abbreviated as SWCNT) consisting of one layer, a double-walled carbon nanotube (hereinafter abbreviated as DWCNT) consisting of two layers shown in FIG. 1 (b), and 3 shown in FIG. 1 (c). There are multi-walled carbon nanotubes (hereinafter abbreviated as MWCNT) having a multi-layer structure of more than one layer, cup-stacked carbon nanotubes (hereinafter abbreviated as CSCNT) shown in FIG. On the other hand, there are also types such as a vapor-grown carbon fiber (hereinafter abbreviated as VGCF) shown in FIG. 1 (d), a carbon nanohorn (hereinafter abbreviated as CNH) and carbon nanofibers shown in FIG. 1 (f).
By including at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes as the nanocarbon material, it has a structure that can be doped with an alkali metal, and an effect that carrier density can be improved can be obtained.
In the case of using multi-walled carbon nanotubes, it preferably has a total number of 25 layers or less, more preferably 10 layers or less from the viewpoint that it can easily spread between graphite and can be doped with many alkali metals.
These nanocarbon materials are produced by an arc discharge method, a chemical vapor synthesis method (DVD method), an arc discharge method, a laser ablation method, a hydrocarbon catalyst synthesis method, a silicon carbide (SiC) high-temperature treatment method, or the like. .
本発明で用いられるナノカーボン材は、特に曲率を持つグラファイト面を有することで、より優れた変形能力を示し、水素ガスの吸蔵時や放出時に水素吸蔵金属等の体積変化による歪が生じても、ナノカーボン材の変形によりその歪が吸収され、水素吸蔵金属等に欠陥が発生しにくくなる。
その様子を、図２に模式的に表す。水素吸蔵金属等の粉末とナノカーボン材とからなる複合体が、水素吸蔵により、水素吸蔵金属等の粉末間のナノカーボンが歪み、収縮する様子（図２の右図）、及び水素放出により、ナノカーボンの歪が開放され元の形状に戻る様子（図２の左図）を模式的に図示したものである。
複合体に適度の割合で混合されたナノカーボンが、水素吸蔵、放出に伴い収縮、膨張することにより、水素吸蔵金属等の内部応力を減少させ、水素吸蔵金属等に欠陥が発生するのを防ぐ効果が発揮される。
The nanocarbon material used in the present invention has a particularly deformable graphite surface, and thus exhibits a better deformation capacity, even when hydrogen gas is occluded or released due to distortion caused by volume change of the hydrogen occlusion metal or the like. The deformation of the nanocarbon material absorbs the strain, so that defects are hardly generated in the hydrogen storage metal or the like.
This is schematically shown in FIG. A composite composed of a powder of hydrogen storage metal or the like and a nanocarbon material is distorted and contracted by hydrogen storage, the nanocarbon between the powder of hydrogen storage metal or the like (right diagram in FIG. 2), and by hydrogen release, FIG. 2 schematically shows how the nanocarbon strain is released and returns to its original shape (the left diagram in FIG. 2).
Nanocarbon mixed in an appropriate ratio with the composite shrinks and expands along with hydrogen storage and release, thereby reducing internal stress of the hydrogen storage metal and preventing defects in the hydrogen storage metal and the like. The effect is demonstrated.
ナノカーボン材は、その大きさがナノサイズであるために分散性に優れ、また繊維状であるために水素吸蔵金属等の間に位置して、水素吸蔵金属等の凝集を防止すると共に電子移動距離の長さを十分に確保することができる。従って、酸化還元反応を促進する導電助剤として効果的に機能することができる。 Nano-carbon materials are nano-sized, so they have excellent dispersibility, and because they are fibrous, they are positioned between hydrogen-occluded metals, etc., preventing aggregation of hydrogen-occluded metals and transferring electrons. A sufficient length of distance can be secured. Therefore, it can function effectively as a conductive additive that promotes the redox reaction.
前記水素吸蔵材料中において、ナノカーボン材が水素吸蔵金属及び／又は合金１００質量部に対して、０．１〜１０質量部含有されていることが好ましく、１〜５質量部含有されているのが特に好ましい。このような配合割合とすることにより、上記効果を効果的に発揮することができる。 In the hydrogen storage material, the nanocarbon material is preferably contained in an amount of 0.1 to 10 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass of the hydrogen storage metal and / or alloy. Is particularly preferred. By setting it as such a mixture ratio, the said effect can be exhibited effectively.
（ナノカーボンの層数、粒度の測定）
上記それぞれのナノカーボンをＴＥＭ（透過型電子顕微鏡、Transmission Electron Microscope）で観察し、観察できたナノカーボンから５０個を無作為に抽出する。形状がチューブ状のナノカーボンは（図１（ａ）〜（ｃ）など）、その軸に対して垂直方向の中心を通る長さの平均値をナノカーボンの平均直径とする。カーボンナノホーン（ＣＮＨ）など形状がチューブ状でない場合は（図１（ｆ））、その形状の最大直径となる部分を測定し、抽出した５０個のカーボンナノホーンにおいて、その最大直径値の平均をそのカーボンナノホーンの平均直径（ｄ）とする。
(Measurement of the number of nanocarbon layers and particle size)
Each of the above nanocarbons is observed with a TEM (Transmission Electron Microscope), and 50 pieces are randomly extracted from the observed nanocarbons. In the case of nanocarbon having a tubular shape (such as FIGS. 1A to 1C), the average value of the length passing through the center in the direction perpendicular to the axis is taken as the average diameter of the nanocarbon. When the shape such as carbon nanohorn (CNH) is not a tube shape (FIG. 1 (f)), the portion having the maximum diameter of the shape is measured, and the average of the maximum diameter values of the extracted 50 carbon nanohorns is It is set as the average diameter (d) of carbon nanohorn.
同様にそれぞれのナノカーボンをＴＥＭ観察し、観察できたナノカーボンから５０個を無作為に抽出する。形状がチューブ状のナノカーボンは、その長軸に対して垂直方向にグラファイト層が何層あるかを数える。グラファイト層が確認できない場合は、グラファイト層の厚みを測定し、その厚みをカーボンナノチューブにおける平均的なグラファイト層間距離である０．３４ｎｍで除算することにより層数を算出する。これらの方法で得たグラファイト層数の平均値をナノカーボンの平均層数（ｎ）とする。形状がチューブ状でないカーボンナノホーン（ＣＮＨ）においては層数を１層とする。 Similarly, each nanocarbon is observed by TEM, and 50 pieces are randomly extracted from the observed nanocarbon. Tube-shaped nanocarbon counts how many graphite layers are perpendicular to its long axis. When the graphite layer cannot be confirmed, the thickness of the graphite layer is measured, and the number of layers is calculated by dividing the thickness by 0.34 nm which is an average graphite interlayer distance in the carbon nanotube. The average value of the number of graphite layers obtained by these methods is defined as the average number of nanocarbon layers (n). In carbon nanohorn (CNH) whose shape is not tube-shaped, the number of layers is one.
上記測定方法により、本明細書の実施例、比較例で採用したナノカーボンの平均層数（ｎ）は、単層カーボンナノチューブ（ＳＷＣＮＴ）は１層、多層カーボンナノチューブ（ＭＷＣＮＴ）は３６層、カーボンナノホーン（ＣＮＨ）は１層、気相成長炭素繊維（ＶＧＣＦ）は２２０層であることがわかった。 According to the above measurement method, the average number of nanocarbon layers (n) employed in the examples and comparative examples of the present specification is one for single-walled carbon nanotubes (SWCNT), 36 for multi-walled carbon nanotubes (MWCNT), carbon It was found that nanohorn (CNH) has one layer and vapor grown carbon fiber (VGCF) has 220 layers.
それぞれのナノカーボンの平均長さは、ナノカーボンを有機溶媒に分散させ、レーザ回折式粒度分布測定装置（日機装（株）製マイクロトラックＭＴ３３００ＥＸ粒度分布測定装置）を用いて測定した。本明細書の実施例、比較例で使用したナノカーボンの平均長さ（Ｌ）は上記粒度分布測定により、カーボンナノホーン（ＣＮＨ）は８０ｎｍ程度、単層カーボンナノチューブ（ＳＷＣＮＴ）、二層カーボンナノチューブ（ＤＷＣＮＴ）、及び多層カーボンナノチューブ（ＭＷＣＮＴ）はいずれも10,000ｎｍ程度、カップスタック状カーボンナノチューブ（ＣＳＣＮＴ）と気相成長炭素繊維（ＶＧＣＦ）は共に15,000ｎｍ程度であることがわかった。 The average length of each nanocarbon was measured by dispersing the nanocarbon in an organic solvent and using a laser diffraction particle size distribution measuring device (Microtrack MT3300EX particle size distribution measuring device manufactured by Nikkiso Co., Ltd.). The average length (L) of the nanocarbon used in the examples and comparative examples of the present specification is about 80 nm from the particle size distribution measurement, the carbon nanohorn (CNH) is about 80 nm, the single-walled carbon nanotube (SWCNT), the double-walled carbon nanotube ( DWCNT) and multi-walled carbon nanotubes (MWCNT) were both about 10,000 nm, and cup-stacked carbon nanotubes (CSCNT) and vapor grown carbon fibers (VGCF) were both about 15,000 nm.
本発明の水素吸蔵材料中において、ナノカーボン材は、水素吸蔵金属及び／又は合金１００質量部に対して、０．１〜１０質量部含有されていることが好ましく、１〜５質量部含有されていることが特に好ましい。ナノカーボン材の含有量が前記１０質量部を超えても水素の吸蔵量の増加効果は少ない。また前記０．１質量部未満では、水素吸蔵金属等の間に位置して、隣り合う水素吸蔵金属等同士の接触による内部応力の増加を抑制すると共に水素吸蔵による膨張の緩衝材として作用して、粉化による水素吸蔵材料の劣化を防止する効果が顕著ではない。 In the hydrogen storage material of the present invention, the nanocarbon material is preferably contained in an amount of 0.1 to 10 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass of the hydrogen storage metal and / or alloy. It is particularly preferable. Even if the content of the nanocarbon material exceeds 10 parts by mass, the effect of increasing the amount of occlusion of hydrogen is small. If the amount is less than 0.1 parts by mass, it is located between the hydrogen storage metals and the like, and suppresses an increase in internal stress due to contact between adjacent hydrogen storage metals and acts as a buffer for expansion due to hydrogen storage. The effect of preventing deterioration of the hydrogen storage material due to powdering is not significant.
[ハ] アルカリ金属
本発明は、ナノカーボン材、並びに水素吸蔵金属及び／又は合金からなる複合体中のナノカーボン材がアルカリ金属でドープされていることに特に特徴がある。
尚、本発明においては、予めナノカーボン材をアルカリ金属でドープしてから水素吸蔵金属等と混合した後に複合体を形成してもよく、又ナノカーボン材と水素吸蔵金属等とを混合した後にアルカリ金属でドープしてもよい。
ナノカーボン材のドープに使用するアルカリ金属は、Ｌｉ、Ｎａ及びＫから選択された１種又は２種以上からなることが望ましいが、Ｋは、軽量であることから特に好ましく、複数種類のアルカリ金属を含む場合においてもＫを同時に含むことが好ましい。
[C] Alkali Metal The present invention is particularly characterized in that the nanocarbon material and the nanocarbon material in the composite made of a hydrogen storage metal and / or alloy are doped with an alkali metal.
In the present invention, a nanocarbon material may be pre-doped with an alkali metal and then mixed with a hydrogen storage metal or the like, and then a composite may be formed, or after the nanocarbon material and the hydrogen storage metal or the like are mixed. You may dope with an alkali metal.
The alkali metal used for the doping of the nanocarbon material is preferably one or more selected from Li, Na and K, but K is particularly preferable because of its light weight. Even when it contains, it is preferable to contain K simultaneously.
アルカリ金属は、ドープされてナノカーボン材のグラファイト層間又はグラファイト束の隙間に分散して存在して、ナノカーボンのキャリア密度を高めて、電荷の移動を容易にし、その結果電荷状態に依存する水素吸蔵等の表面での水素乖離速度を高めて、水素吸収速度が向上すると考えられる。
尚、アルカリ金属の添加量は、ナノカーボン材１００質量部に対して、１〜５０質量部が好ましく、１０〜２０質量部が特に好ましい。また、複数種類のアルカリ金属を含む場合には、全てのアルカリ金属量の合計が上記範囲に含まれるものとする。
アルカリ金属の添加量を前記５０質量部以下とすることにより、ナノカーボンの変形が塑性変形になるという不都合が生じるのを抑制でき、また前記１質量部以上とすることにより、水素吸収速度が向上する効果を効果的に発揮できる。
ナノカーボン材がアルカリ金属によりドープされていることの確認は、ナノカーボン材における任意の複数箇所をＴＥＭ（透過電子顕微鏡、例えば日本電子（株）製）を使用してアルカリ金属の存在を観察し、そのうちの相当割合にアルカリ金属分散を観察することにより、ナノカーボン材がアルカリ金属でドープされていることを確認することができる。アルカリ金属によるナノカーボン材のドープは、例えば蒸着法により実施することができる。
Alkali metal is doped and exists in the nanocarbon material between graphite layers or in the gaps between the graphite bundles, increasing the carrier density of the nanocarbon, facilitating charge transfer, and as a result, hydrogen depending on the charge state. It is thought that the hydrogen absorption rate is improved by increasing the hydrogen dissociation rate on the surface such as occlusion.
In addition, 1-50 mass parts is preferable with respect to 100 mass parts of nanocarbon materials, and, as for the addition amount of an alkali metal, 10-20 mass parts is especially preferable. When a plurality of types of alkali metals are included, the total amount of all alkali metals is included in the above range.
By making the addition amount of the alkali metal 50 parts by mass or less, it is possible to suppress the disadvantage that the deformation of the nanocarbon becomes plastic deformation, and by making the addition amount 1 part by mass or more, the hydrogen absorption rate is improved. Can effectively demonstrate the effect.
To confirm that the nanocarbon material is doped with an alkali metal, the presence of the alkali metal is observed by using a TEM (transmission electron microscope, for example, manufactured by JEOL Ltd.) at any plurality of locations in the nanocarbon material. By observing the alkali metal dispersion in a considerable proportion, it can be confirmed that the nanocarbon material is doped with an alkali metal. The nanocarbon material can be doped with an alkali metal by, for example, a vapor deposition method.
[２] 第２の態様
本発明の第２の態様は、前記した水素吸蔵材料を有する水素吸蔵手段、熱制御手段及び圧力制御手段を備えた水素貯蔵容器に関する発明である。
本発明の水素貯蔵容器には、前記水素吸蔵材料を封入して、比較的低温または高圧雰囲気において水素を吸蔵して発熱し、一方、比較的高温または低圧雰囲気において水素を放出する。このような水素ガスの吸蔵、放出手段は、熱制御手段、圧力制御等により効率よく行うことができる。
例えば連続的な水素の吸蔵・放出を行う場合には、水素貯蔵容器を高密度セル分割型容器として、複数のセルの各々に水素吸蔵材料を封入して、各セル１内の水素吸蔵材料は、ヒーターにより、セル毎に温度制御ができるようにすることができる。熱制御手段は、水素吸蔵材料に水素を吸収、放出させるためには該材料を冷却、加熱する必要がある。このような冷却、加熱手段としては熱媒体用のパイプ、放熱用フィン等が例示できる。圧力制御手段は、圧縮機、圧力調節弁等を使用して行うことができる。
このような容器とすることにより、水素放出速度を良好に制御できる。又、水素貯蔵容器には安全性が高く軽量な高強度耐熱アルミニウム合金製容器が好適である。
このような水素貯蔵容器は、車載モジュールや携帯用モジュールに利用できる。
[2] Second Aspect A second aspect of the present invention is an invention relating to a hydrogen storage container provided with a hydrogen storage means having the above-described hydrogen storage material, a heat control means, and a pressure control means.
The hydrogen storage container of the present invention encloses the hydrogen storage material and stores hydrogen in a relatively low temperature or high pressure atmosphere to generate heat, while releasing hydrogen in a relatively high temperature or low pressure atmosphere. Such hydrogen gas occlusion and release means can be efficiently performed by heat control means, pressure control and the like.
For example, when performing continuous storage and release of hydrogen, the hydrogen storage container is a high-density cell division type container, a hydrogen storage material is sealed in each of a plurality of cells, and the hydrogen storage material in each cell 1 is The temperature can be controlled for each cell by the heater. The heat control means needs to cool and heat the hydrogen storage material in order to absorb and release hydrogen. Examples of such cooling and heating means include a heat medium pipe, a heat radiation fin, and the like. The pressure control means can be performed using a compressor, a pressure control valve, or the like.
By using such a container, the hydrogen release rate can be controlled well. As the hydrogen storage container, a highly safe and lightweight high strength heat-resistant aluminum alloy container is suitable.
Such a hydrogen storage container can be used for an in-vehicle module or a portable module.
[５] 第３態様に係る水素吸蔵材料の製造方法は、アルカリ金属でドープされたナノカーボン材料と、水素吸蔵金属及び／又は合金とを有機溶媒中で混合した後に該有機溶媒を蒸発除去し、得られた混合粉末を金型内で圧縮成形し、その後不活性ガス雰囲気下で焼結することを特徴とする。
具体例として、例えばアルカリ金属がドープされたナノカーボン材を空気に曝さないように有機溶媒溶液中に取り出す。この溶媒溶液に水素吸蔵合金を添加する。更に必要により連結材を添加し、それぞれが均一に混ざるように十分に撹拌する。次に真空容器に移し、撹拌下に有機溶媒を蒸発除去して混合粉体を得る。得られた混合粉体を金型に入れて、加圧下で圧縮成形し、この圧縮成形体をアルゴンガス雰囲気下６００℃で焼結して、ハイブリッド状態の焼結体を得る。
尚、本発明において、ハイブリッドとは合金粉末とナノカーボン材とが混合されている状態で、合金粉末の少なくとも一部がナノカーボン材に拘束されていることをいう。以下、このような状態にある焼結体、成形体をそれぞれハイブリッド焼結体、又はハイブリッド成形体ということがある。
[5] The method for producing a hydrogen storage material according to the third aspect includes mixing a nanocarbon material doped with an alkali metal and a hydrogen storage metal and / or alloy in an organic solvent, and then evaporating and removing the organic solvent. The obtained mixed powder is compression molded in a mold and then sintered in an inert gas atmosphere.
As a specific example, for example, a nanocarbon material doped with an alkali metal is taken out into an organic solvent solution so as not to be exposed to air. A hydrogen storage alloy is added to the solvent solution. Further, if necessary, a connecting material is added and sufficiently stirred so that each is uniformly mixed. Next, the mixture is transferred to a vacuum container, and the organic solvent is removed by evaporation with stirring to obtain a mixed powder. The obtained mixed powder is put into a mold, compression-molded under pressure, and the compression-molded body is sintered at 600 ° C. in an argon gas atmosphere to obtain a hybrid sintered body.
In the present invention, the hybrid means that the alloy powder and the nanocarbon material are mixed and at least a part of the alloy powder is restrained by the nanocarbon material. Hereinafter, the sintered body and the molded body in such a state may be referred to as a hybrid sintered body or a hybrid molded body, respectively.
前記第３態様において、アルカリ金属によるナノカーボン材料のドープは、蒸着法により行うのが望ましい。この蒸着法の具体例としては、例えば石英管内の両端にナノカーボンとカリウムをそれぞれは位置後、該石英管内を高真空にしてからシールする。次にマイクロコイルヒータを用いて石英管外部からナノカーボンの配置部分を４００℃程度、カリウムの配置部分を２５０℃程度にそれぞれ８時間程度に加熱、維持する。
以下に実施例により、本発明を具体的に説明するが、本発明は以下の実施例に限定されるものではない。
In the third aspect, it is desirable that the nanocarbon material is doped with an alkali metal by vapor deposition. As a specific example of this vapor deposition method, for example, after nanocarbon and potassium are positioned at both ends of the quartz tube, the quartz tube is sealed in a high vacuum after sealing. Next, using a microcoil heater, the arrangement part of nanocarbon is heated and maintained at about 400 ° C. and the arrangement part of potassium at about 250 ° C. for about 8 hours from the outside of the quartz tube.
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
以下に、実施例１〜８及び比較例１を記載するが、実施例１〜８に係る表１〜５及び７〜９，並びに図３〜７及び９〜１１には比較を容易にするために実施例の範囲外の評価結果も合わせて示す。
尚、本実施例と比較例に使用した試料の調製方法とその評価方法は以下の[１]ないし[３]に記載する。
[１] 水素吸蔵材料の調製
（ナノカーボン材のアルカリ金属ドープ）
内容積１００ｍｌの石英管内の両端にナノカーボン材（ナノカーボン材の種類については各実施例に記載されている）０．０５ｇとカリウム０．５ｇをそれぞれ配置する。石英管内をロータリーポンプにて真空引きを行い、さらにＤＰポンプによる真空引きにて１×１０−４torrまで真空度を上げてから真空封入する。
マイクロコイルヒータを用いて石英管外部からナノカーボンの部分を４００℃、カリウムの部分を２５０℃まで昇温して、８時間それぞれ前記温度に維持した。
Examples 1 to 8 and Comparative Example 1 are described below, but Tables 1 to 5 and 7 to 9 according to Examples 1 to 8 and FIGS. 3 to 7 and 9 to 11 are for easy comparison. The results of evaluation outside the scope of the examples are also shown.
The sample preparation methods and evaluation methods used in the examples and comparative examples are described in [1] to [3] below.
[1] Preparation of hydrogen storage materials (alkali metal doping of nanocarbon materials)
0.05 g of nanocarbon material (the type of nanocarbon material is described in each example) and 0.5 g of potassium are arranged at both ends in a quartz tube having an internal volume of 100 ml. The quartz tube is evacuated by a rotary pump, and further vacuumed by a DP pump to 1 × 10 −4 torr and sealed.
Using a microcoil heater, the nanocarbon portion was heated to 400 ° C. and the potassium portion to 250 ° C. from the outside of the quartz tube, and maintained at the above temperature for 8 hours.
（ハイブリッド焼結体の調製）
真空封入し、加熱処理によりカリウムをドープさせたナノカーボン材を空気に曝さないように有機溶媒テトラヒドロフラン(以下ＴＨＦ)２００ｍｌ溶液中に取り出す。その溶媒に水素吸蔵合金（金属）を４．９５ｇ添加する。さらに連結材として流動バラフィンを０．６ｇ添加し、それぞれが均一に混ざるように３０分間撹拌を行った。
次に真空容器に移し、撹拌下に有機溶媒を蒸発除去して混合粉体を作製した。
得られた混合粉体を２７ｍｍφの金型に入れて、５００ｋｇｆ／ｃｍ２の加圧下で圧縮成形して、ハイブリッド成形体を得た。この成形体をアルゴンガス雰囲気下６００℃で焼結して、ハイブリッド焼結体を得ることができる。
(Preparation of hybrid sintered body)
The nanocarbon material doped with potassium by heat treatment is taken out into a 200 ml organic solvent tetrahydrofuran (hereinafter THF) solution so as not to be exposed to air. 4.95 g of a hydrogen storage alloy (metal) is added to the solvent. Further, 0.6 g of fluidized ballaffin was added as a connecting material, and stirring was performed for 30 minutes so that each was mixed uniformly.
Next, the mixture was transferred to a vacuum container, and the organic solvent was removed by evaporation with stirring to produce a mixed powder.
The obtained mixed powder was put into a 27 mmφ mold and compression molded under a pressure of 500 kgf / cm 2 to obtain a hybrid molded body. This molded body can be sintered at 600 ° C. in an argon gas atmosphere to obtain a hybrid sintered body.
（測定前の活性処理）
得られたハイブリッド焼結体をステンレス製容器に挿入し、この容器中の空気を真空引きで除去する。さらにハイブリッド焼結体に水素が出入りし易くするために、真空引きを行いながら容器を８０℃まで加熱して、８０℃での真空引きを６０分間維持する。この操作を活性化処理とする。
(Activation treatment before measurement)
The obtained hybrid sintered body is inserted into a stainless steel container, and the air in the container is removed by vacuuming. Further, in order to make hydrogen easily enter and exit the hybrid sintered body, the container is heated to 80 ° C. while evacuating, and the evacuation at 80 ° C. is maintained for 60 minutes. This operation is an activation process.
（安定化処理）
その後、水素ガスを５ＭＰａでステンレス製容器に導入し３０分維持させ、ハイブリッド焼結体へ水素を吸蔵させ、さらに真空引きを３０分行い、水素を放出させる。この３０分の水素吸蔵・放出を１０回繰り返した。この処理を安定化処理とする。
(Stabilization process)
Thereafter, hydrogen gas is introduced into a stainless steel container at 5 MPa and maintained for 30 minutes, hydrogen is occluded in the hybrid sintered body, and evacuation is further performed for 30 minutes to release hydrogen. This 30-minute hydrogen storage / release was repeated 10 times. This process is referred to as a stabilization process.
[２]水素吸蔵量と水素吸収速度の測定法
（水素吸蔵量の測定法）
本発明の水素吸蔵材料についての水素吸収速度を得るために、ステンレス製水素貯蔵容器の温度を３０℃、導入水素圧力を３．７ＭＰａとし、容器を密閉し、その水素圧力と時間の推移を測定した。水素吸蔵により水素ガスが減少し、密閉容器内の水素圧が下がるため、その下がった分の圧力と容器内の体積から水素吸蔵量を求める。
[2] Method for measuring hydrogen storage and hydrogen absorption rate (Method for measuring hydrogen storage)
In order to obtain the hydrogen absorption rate of the hydrogen storage material of the present invention, the temperature of the stainless steel hydrogen storage container was set to 30 ° C., the introduced hydrogen pressure was set to 3.7 MPa, the container was sealed, and the transition of the hydrogen pressure and time was measured. did. Since the hydrogen gas is reduced by the occlusion of hydrogen and the hydrogen pressure in the sealed container is lowered, the hydrogen occlusion amount is obtained from the pressure and the volume in the container.
（水素吸収速度の測定法）
導かれた水素吸蔵量−時間の推移において水素吸収条件としての水素圧は変化しているため、水素吸収速度としてその傾きを用いることは不適である。そこで自触式反応の速度式 ｌｎ（ｙ／(１−ｙ)）＝ｋｔに値を代入する。
上式において、yを水素吸蔵量／最大水素吸蔵量、tを時間(sec)、ｋを水素吸収速度定数とし、その水素吸収速度定数ｋを用いて水素吸収速度を評価する。
（８０％水素吸収所要時間の算出）
上記水素吸収速度定数ｋを用いて、自触式反応の速度式（ｌｎ（ｙ／１−ｙ））＝ｋｔからｙ＝０．８のときのｔを求める。これにより、同一条件で水素吸収を行った場合の８０％まで水素を吸蔵するまでかかる時間、すなわち８０％水素吸収所要時間ｔが求められる。
(Measurement method of hydrogen absorption rate)
Since the hydrogen pressure as the hydrogen absorption condition changes in the transition of the introduced hydrogen storage amount-time, it is inappropriate to use the slope as the hydrogen absorption rate. Therefore, a value is substituted into the rate equation ln (y / (1-y)) = kt of the self-touching reaction.
In the above equation, y is hydrogen storage amount / maximum hydrogen storage amount, t is time (sec), k is hydrogen absorption rate constant, and the hydrogen absorption rate constant k is used to evaluate the hydrogen absorption rate.
(Calculation of 80% hydrogen absorption time)
Using the hydrogen absorption rate constant k, the rate equation (ln (y / 1−y)) = kt to t for the self-touching reaction is obtained. Thereby, the time required to occlude hydrogen up to 80% when hydrogen absorption is performed under the same conditions, that is, the 80% hydrogen absorption required time t is obtained.
[３] ナノカーボン材へのアルカリ金属分散の確認
水素吸蔵材料中のナノカーボン材における任意の２０箇所で測定してそのうちの８割以上にアルカリ金属が存在することをＴＥＭ（透過電子顕微鏡、日本電子（株）製）を用いて観察することにより、ナノカーボン材がアルカリ金属でドープされていることを確認した。
[3] Confirmation of alkali metal dispersion in nanocarbon material TEM (Transmission Electron Microscope, Japan) measured at 20 arbitrary locations in the nanocarbon material in the hydrogen storage material and more than 80% of the alkali metal was present. It was confirmed that the nanocarbon material was doped with an alkali metal by observing using an electron).
[実施例１]
平均粒径１０μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、Ｋでドープしたカーボンナノホーン（ＣＮＨ 平均層数１層で平均長さは８０ｎｍ）をそれぞれ０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部となるようにハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸蔵特性を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。更に求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸蔵までに要する時間を算出した。表１、及び図３にそれぞれサンプルと水素吸収速度定数（図３（Ａ））と８０％水素吸蔵までに要する時間（図３（Ｂ））を示す。
図３（Ａ）より、Ｍｇ２Ｎｉ１００質量部に対し、カーボンナノホーン０．１〜１０質量部の範囲で水素吸収速度の向上が見られる。
[Example 1]
Carbon nanohorns doped with K (average number of CNH: 1 layer, average length: 80 nm) with respect to 100 parts by mass of hydrogen storage alloy Mg 2 Ni with an average particle size of 10 μm are 0, 0.1, 0.2,. A hydrogen storage material was prepared by the method described in [1] Preparation of hydrogen storage material, except that it was hybridized to 5, 1.0, 2.0, 5.0, 10, 20 parts by mass. The storage characteristics were measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. Further, from the obtained hydrogen absorption rate constant, the time required to occlude 80% hydrogen under 3.7 MPa hydrogen pressure was calculated. Table 1 and FIG. 3 show the sample, the hydrogen absorption rate constant (FIG. 3A), and the time required for 80% hydrogen storage (FIG. 3B), respectively.
From FIG. 3 (A), the hydrogen absorption rate is improved in the range of 0.1 to 10 parts by mass of carbon nanohorn with respect to 100 parts by mass of Mg 2 Ni.
[実施例２]
平均粒径２００、１００、５０、２０、３μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、それぞれにＫをドープしたカーボンナノホーン（ＣＮＨ 実施例１で使用したと同じもの）１質量部となるようにハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸蔵特性を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。更に求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸蔵までにかかる時間を算出した。表２、及び図４にそれぞれサンプルと水素吸収速度定数（図４（Ａ））と８０％水素吸蔵までに要する時間（図４（Ｂ））を示す。
図４（Ａ）より、水素吸蔵合金の平均粒径５０μｍφ以下の条件で水素吸収速度の向上が見られる。
[Example 2]
To 100 parts by mass of hydrogen storage alloy Mg 2 Ni having an average particle size of 200, 100, 50, 20, 3 μm, 1 part by mass of carbon nanohorns doped with K (same as used in CNH Example 1). A hydrogen storage material was prepared by the method described in [1] Preparation of hydrogen storage material except for the hybrid, and the hydrogen storage characteristics were measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. Furthermore, the time taken for 80% hydrogen storage under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 2 and FIG. 4 show the sample, the hydrogen absorption rate constant (FIG. 4A), and the time required for 80% hydrogen storage (FIG. 4B), respectively.
As shown in FIG. 4A, the hydrogen absorption rate is improved under the condition that the average particle size of the hydrogen storage alloy is 50 μmφ or less.
[実施例３]
カーボンナノホーン１００質量部に対し、Ｋを０．１、１、５、２０、５０、６０質量部となるようにＫをドープし、平均粒径１０μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、上記割合でＫドープしたカーボンナノホーン（ＣＮＨ 実施例１で使用したと同じもの）１質量部となるようにハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸蔵特性を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。更に求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸蔵までにかかる時間を算出した。表３、及び図５にそれぞれサンプルと水素吸収速度定数（図５（Ａ））と８０％水素吸蔵までに要する時間（図５（Ｂ））を示す。
図５（Ａ）より、Ｋドープ量が上記１〜５０質量部の範囲で水素吸収速度の向上が見られる。そこで、以降の実施例においてはナノカーボン１００質量部へのＫドープ割合は２０質量部とした。
[Example 3]
For 100 parts by mass of carbon nanohorn, K is doped so that K is 0.1, 1, 5, 20, 50, 60 parts by mass, and for 100 parts by mass of hydrogen storage alloy Mg 2 Ni with an average particle size of 10 μm, A hydrogen storage material was produced by the method described in [1] Preparation of hydrogen storage material, except that it was hybridized to 1 part by mass of carbon nanohorn K-doped at the above ratio (the same as that used in CNH Example 1). Then, the hydrogen storage characteristics were measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. Furthermore, the time taken for 80% hydrogen storage under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 3 and FIG. 5 show the sample, the hydrogen absorption rate constant (FIG. 5A), and the time required for 80% hydrogen storage (FIG. 5B), respectively.
As shown in FIG. 5A, the hydrogen absorption rate is improved when the K doping amount is in the range of 1 to 50 parts by mass. Therefore, in the following examples, the K doping ratio to 100 parts by mass of nanocarbon was set to 20 parts by mass.
[実施例４]
平均粒径１０μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、Ｋをドープした単層カーボンナノチューブ（ＳＷＣＮＴ 平均層数１層で平均長さは10,000ｎｍ）０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部をそれぞれハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸収を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸収までにかかる時間を算出した。表４、及び図６にそれぞれサンプルと水素吸収速度定数（図６（Ａ））と８０％水素吸蔵までに要する時間（図６（Ｂ））を示す。
図６（Ａ）より、合金Ｍｇ２Ｎｉ１００質量部に対し、ＫをドープしたＳＷＣＮＴ重量比１〜１０質量部の範囲で水素吸収速度の向上が見られる。
[Example 4]
Single-walled carbon nanotubes doped with K (average number of SWCNTs is 1 layer and average length is 10,000 nm) with respect to 100 parts by mass of hydrogen storage alloy Mg 2 Ni with an average particle size of 10 μm 0, 0.1, 0.2, 0 .5, 1.0, 2.0, 5.0, 10 and 20 parts by mass, except that each was hybridized to produce a hydrogen occlusion material by the method described in [1] Preparation of hydrogen occlusion material. Was measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. The time required for 80% hydrogen absorption under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 4 and FIG. 6 show the sample, the hydrogen absorption rate constant (FIG. 6A), and the time required for 80% hydrogen storage (FIG. 6B), respectively.
FIG. 6 (A) shows an improvement in the hydrogen absorption rate in the range of 1 to 10 parts by mass of the SWCNT weight ratio doped with K with respect to 100 parts by mass of the alloy Mg 2 Ni.
[実施例５]
平均粒径１０μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、Ｋをドープした多層カーボンナノチューブ（ＭＷＣＮＴ 平均層数は３６層で平均長さは10,000ｎｍ）０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部をそれぞれハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸収特性を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸収までにかかる時間を算出した。表５、及び図７にそれぞれサンプルと水素吸収速度定数（図７（Ａ））と８０％水素吸蔵までに要する時間（図７（Ｂ））を示す。
図７（Ａ）より、Ｍｇ２Ｎｉ１００質量部に対し、ＫをドープしたＭＷＣＮＴ重量比０．１〜１０質量部の範囲で水素吸収速度の向上が見られる。
[Example 5]
Multi-layer carbon nanotubes doped with K (average number of MWCNTs is 36 and average length is 10,000 nm) with respect to 100 parts by mass of hydrogen storage alloy Mg 2 Ni with an average particle size of 10 μm 0, 0.1, 0.2, 0 .5, 1.0, 2.0, 5.0, 10 and 20 parts by mass, except that each was hybridized to produce a hydrogen occlusion material by the method described in [1] Preparation of hydrogen occlusion material. Characteristics were measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. The time required for 80% hydrogen absorption under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 5 and FIG. 7 show the sample, the hydrogen absorption rate constant (FIG. 7A), and the time required for 80% hydrogen storage (FIG. 7B), respectively.
From FIG. 7A, the hydrogen absorption rate is improved in the range of 0.1 to 10 parts by mass of the MWCNT weight ratio doped with K with respect to 100 parts by mass of Mg 2 Ni.
[比較例１]
平均粒径１０μｍの水素吸蔵合金Ｍｇ２Ｎｉ１００質量部に対し、Ｋをドープした気相成長炭素繊維（ＶＧＣＦ 平均層数220層で平均長さは15,000ｎｍ）０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部をそれぞれハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製して、水素吸収特性を測定した。
水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸収までにかかる時間を算出した。表６、及び図８にそれぞれサンプルと水素吸収速度定数（図８（Ａ））と８０％水素吸蔵までに要する時間（図８（Ｂ））を示す。図８（Ａ）より、カーボンナノチューブがＶＧＣＦでは水素吸収速度の向上が見られなかった。
[Comparative Example 1]
100 parts by mass of hydrogen storage alloy Mg 2 Ni with an average particle size of 10 μm, vapor-grown carbon fiber doped with K (VGCF average number of layers 220, average length is 15,000 nm) 0, 0.1, 0.2, A hydrogen storage material was prepared by the method described in [1] Preparation of hydrogen storage material, except that 0.5, 1.0, 2.0, 5.0, 10, and 20 parts by mass were hybridized. Absorption characteristics were measured.
The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. The time required for 80% hydrogen absorption under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 6 and FIG. 8 show the sample, the hydrogen absorption rate constant (FIG. 8A), and the time required for 80% hydrogen storage (FIG. 8B), respectively. FIG. 8A shows that the hydrogen absorption rate is not improved when the carbon nanotube is VGCF.
[実施例６]
平均粒径が１０μｍの水素吸蔵合金ＬａＮｉ５ １００質量部に対し、Ｋをドープしたカーボンナノホーン（ＣＮＨ 実施例１で使用したと同じもの）０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部をハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製した。
それぞれの合金に対応した初期活性処理を行い、吸蔵圧が同じ程度になるように４０℃の温度条件下で水素吸収特性を測定した。水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸収までにかかる時間を算出した。表７、及び図９にそれぞれサンプルと水素吸収速度定数（図９（Ａ））と８０％水素吸蔵までに要する時間（図９（Ｂ））を示す。図９（Ａ）より、ＬａＮｉ５ １００質量部に対し、グラファイト層が１層であるＣＮＨ１〜１０質量部の範囲で水素吸収速度の向上が見られた。
[Example 6]
Carbon nanohorn doped with K (same as used in CNH Example 1) 0, 0.1, 0.2, 0.5, 1 for 100 parts by mass of hydrogen storage alloy LaNi 5 with an average particle size of 10 μm Except for hybridizing 0.0, 2.0, 5.0, 10, and 20 parts by mass, a hydrogen storage material was prepared by the method described in [1] Preparation of hydrogen storage material.
The initial activation treatment corresponding to each alloy was performed, and the hydrogen absorption characteristics were measured under a temperature condition of 40 ° C. so that the occlusion pressure was the same. The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. The time required for 80% hydrogen absorption under 3.7 MPa hydrogen pressure was calculated from the obtained hydrogen absorption rate constant. Table 7 and FIG. 9 show the sample, the hydrogen absorption rate constant (FIG. 9A), and the time required for 80% hydrogen storage (FIG. 9B), respectively. From FIG. 9 (A), the hydrogen absorption rate was improved in the range of 1 to 10 parts by mass of CNH in which the graphite layer was one layer with respect to 100 parts by mass of LaNi 5 .
[実施例７]
平均粒径がそれぞれ２００μｍ、１００μｍ、５０μｍ、２０μｍ、１０μｍ、３μｍの水素吸蔵合金ＦｅＴｉ１００質量部に対し、Ｋをドープしたカーボンナノホーン（ＣＮＨ 実施例１で使用したと同じもの）を０、０．１、０．２、０．５、１．０、２．０、５．０、１０、２０質量部をハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製した。
それぞれの合金に対応した初期活性処理を行い、吸収圧が同じ程度になるように２０℃の温度条件下で水素吸収特性を測定した。水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸蔵までにかかる時間を算出した。表８、及び図１０にそれぞれサンプルと水素吸収速度定数（図１０（Ａ））と８０％水素吸蔵までに要する時間（図１０（Ｂ））を示す。図１０（Ａ）より、合金ＦｅＴｉ１００質量部に対し、グラファイト層が１層であるＣＮＨ１〜１０質量部の範囲で水素吸収速度の向上が見られた。
[Example 7]
Carbon nanohorns doped with K (same as used in CNH Example 1) were added to 0, 0.1 with respect to 100 parts by mass of hydrogen storage alloy FeTi having average particle diameters of 200 μm, 100 μm, 50 μm, 20 μm, 10 μm, and 3 μm, respectively. , 0.2, 0.5, 1.0, 2.0, 5.0, 10 and 20 parts by mass, except that the mass was hybridized by the method described in [1] Preparation of hydrogen storage material. did.
The initial activation treatment corresponding to each alloy was performed, and the hydrogen absorption characteristics were measured under a temperature condition of 20 ° C. so that the absorption pressure was the same. The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. From the obtained hydrogen absorption rate constant, the time required to occlude 80% hydrogen under 3.7 MPa hydrogen pressure was calculated. Table 8 and FIG. 10 show the sample, the hydrogen absorption rate constant (FIG. 10A), and the time required for 80% hydrogen storage (FIG. 10B), respectively. From FIG. 10 (A), the hydrogen absorption rate was improved in the range of 1 to 10 parts by mass of CNH in which the graphite layer was one layer with respect to 100 parts by mass of the alloy FeTi.
[実施例８]
平均粒径が１０μｍの水素吸蔵金属（Ｖ）１００質量部に対し、Ｋをドープしたカーボンナノホーン（ＣＮＨ 実施例１で使用したと同じもの）０、０．１、０．２、０．５、１．０、２．０％質量部をハイブリッドした以外は上記［１］水素吸蔵材料の調製に記載した方法により水素吸蔵材料を作製した。尚、水素吸蔵金属（Ｖ）は、ＢＣＣ合金に相当する。
それぞれの水素吸蔵金属Ｖに対応した初期活性処理を行い、吸収圧が同じ程度になるように４０℃の温度条件下で水素吸収特性を測定した。水素吸蔵量―時間の測定結果より自触式反応式を用いて水素吸収速度定数を求めた。求めた水素吸収速度定数より3.7ＭＰa水素圧下で８０％水素吸収までに要する時間を算出した。表９、及び図１１にそれぞれサンプルと水素吸収速度定数（図１１（Ａ））と８０％水素吸蔵までに要する時間（図１１（Ｂ））を示す。図１１（Ａ）より、水素吸蔵金属（Ｖ）１００質量部に対し、グラファイト層が１層であるＣＮＨ１〜１０質量部の範囲で水素吸収速度の向上が見られた。
[Example 8]
Carbon nanohorn doped with K (same as used in CNH Example 1) 0, 0.1, 0.2, 0.5, 100 parts by mass of hydrogen storage metal (V) having an average particle size of 10 μm A hydrogen storage material was produced by the method described in [1] Preparation of hydrogen storage material, except that 1.0 and 2.0% by mass were hybridized. The hydrogen storage metal (V) corresponds to a BCC alloy.
The initial activation treatment corresponding to each hydrogen storage metal V was performed, and the hydrogen absorption characteristics were measured under a temperature condition of 40 ° C. so that the absorption pressure was the same. The hydrogen absorption rate constant was obtained from the hydrogen storage amount-time measurement result using a self-contacting reaction equation. From the obtained hydrogen absorption rate constant, the time required for 80% hydrogen absorption under 3.7 MPa hydrogen pressure was calculated. Table 9 and FIG. 11 show the sample, the hydrogen absorption rate constant (FIG. 11A), and the time required for 80% hydrogen storage (FIG. 11B), respectively. From FIG. 11 (A), the hydrogen absorption rate was improved in the range of 1 to 10 parts by mass of CNH having one graphite layer with respect to 100 parts by mass of the hydrogen storage metal (V).
本発明の水素吸蔵材料は、水素貯蔵容器に封入して、車載モジュールや携帯用モジュール等に広く利用できる。 The hydrogen storage material of the present invention is enclosed in a hydrogen storage container and can be widely used for in-vehicle modules and portable modules.
１ 水素吸蔵合金
２ ナノカーボン
1 Hydrogen storage alloy 2 Nanocarbon
Claims (12)
12. The method for producing a hydrogen storage material according to claim 11, wherein the doping of the nanocarbon material with an alkali metal is a vapor deposition method.
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| CN113998988A (en) * | 2021-11-09 | 2022-02-01 | 上海超高环保科技股份有限公司 | Method for manufacturing sheet, block, tubular and special-shaped material for hydrogen storage |
| CN114604822A (en) * | 2022-03-30 | 2022-06-10 | 中国华能集团清洁能源技术研究院有限公司 | Hydrogen storage material, hydrogen storage reactor and method |
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