JP4018030B2 - Hydrogen permeable membrane and manufacturing method thereof - Google Patents

Description

【００１７】
このような金属Ａの粒子及び物質Ｂの粒子を準備する。但し、金属Ａの融点の方が物質Ｂの融点よりも高い組み合わせであるものとする。この金属Ａ及び物質Ｂの粉末状粒子は、所定の混合割合として図１（ｂ）に示すように均一に混合し、混合体を所定の温度にまで加熱し、物質Ｂのみを溶解させ、その後に冷却固化させてインゴットからなる固化生成物Ｃを得る。すなわち、加熱・冷却の過程で物質Ｂが一旦溶解してから再度凝固することによりインゴット（固化生成物Ｃ）が得られ、このインゴット中には金属Ａの粉末粒子が分散して含まれることになる。固化生成物Ｃは、物質Ｂの隗の内部に微粒子状の金属Ａが分散材として分散した複合体の構造となつている。
【００１８】
ここで、金属Ａ及び物質Ｂの混合割合は、複合体における金属Ａの割合が、３０〜８０at. ％の範囲、つまり固化生成物Ｃ全体ひいては水素透過膜中に占める金属Ａの割合が３０〜８０ａｔ．％の範囲となるようにすることが好ましい。
【００１９】
こうして得られた固化生成物Ｃからなる材料は、必要に応じて金属Ａの占める割合が低い部分を切除した後、図１（ｃ）に示すように圧延、切削等の加工により薄膜ないし箔状に形成し、金属Ａ及び物質Ｂの複合体からなる水素透過膜Ｄとする。物質Ｂは、延性に優れ、切削性にも優れる。圧延による加工性は、概ね物質Ｂ材料の性質を引き継いでいる。よつて、インゴット（固化生成物Ｃ）の圧延又は切削による加工は、非常に容易に行うことができる。但し、水素透過膜Ｄを固化生成物Ｃの圧延によつて製作するときは、金属Ａの粒子径が水素透過膜Ｄの厚さ以下のものとする。かくして得られる水素透過膜Ｄは、固化生成物Ｃと同様に、水素透過性能に優れる金属Ａと金属Ａを繋ぎ止めるバインダーの役割をする物質Ｂとの複合体ないし混合体からなる。勿論、水素透過膜Ｄは、薄膜の表面から裏面にまで達する通気孔が存在しない状態にあり、不純物ガスが水素透過膜Ｄを通過しない状態にある。
【００２０】
上記のように金属Ａ及び物質Ｂの混合割合を、水素透過膜Ｄ中に占める金属Ａの割合が３０〜８０ａｔ．％の範囲となるように設定する理由は、（１）水素透過膜Ｄ中にて金属Ａの微粒子同士が適度に接触していること、（２）水素透過膜Ｄとするための十分な延性及び加工性を保つこと、という二つの条件を満たすことが望まれるためである。
【００２１】
特に、水素透過性能に優れる金属Ａの粒子が水素透過膜Ｄの膜厚に比して十分に小さく、水素透過膜Ｄの表面から裏面にまで接触状態で連続し、或いは金属Ａの粒子が水素透過膜Ｄの膜厚にほぼ合致し、金属Ａの多くの粒子が、水素透過膜Ｄの表面から裏面にまで貫通状態で存在して水素透過の経路を形成していることが望ましい。すなわち、金属Ａの粒子が水素透過膜Ｄの膜厚に比して十分に小さいとき、水素透過膜Ｄの物質Ｂは多孔質体状をなしているが、この多孔質体が連通孔を有する状態にあれば、水素透過性能に優れる金属Ａの粒子が、水素透過膜Ｄの表面から裏面にまで接触状態で連続している状態にある。物質Ｂに対する金属Ａの割合が極度に少ない場合は金属Ａ粒子同士が接触し難くなるため、水素透過の経路が確保されず不適であるので、金属Ａ粒子同士が接触する状態に混合比を選定する。
【００２２】
水素透過膜Ｄは、連通孔を有する多孔質の支持体Ｅに必要に応じて接合させて重ね合わせた状態で、メンブレンリフォーマーの水素精製器に組み込み、生成させた改質ガスに含まれる水素ガスのみを水素透過膜Ｄ及び支持体Ｅを透過させ、水素を精製して取り出すために使用される。支持体Ｅは、例えばセラミックス、ガラス、ステンレス等の粉末や繊維の焼結体である。必要に応じ、水素透過膜Ｄの表裏両面に水素化触媒かつ酸化防止膜として作用する材料（Ｐｄ，Ｐｔ等）のコーティングを、スパッタリング、メッキ等の手段によつて施した後、水素透過膜Ｄ及び支持体Ｅからなる透過膜構造体とすることができる。
【００２３】
上記方法により作成した水素透過膜Ｄによれば、水素透過現象が起こる際、予め、微粉化してある金属Ａのマクロ的に見た膨張度合いは非常に小さく、また、金属Ａの変形は延性の高い物質Ｂの変形により吸収・緩和される。このため、水素固溶による金属Ａの粒子の膨張に起因する水素透過膜Ｄの表面から裏面へと貫通するような大きなクラックは、長期使用によつても生じ難く、水素以外の不純物ガスが水素精製器の低圧側へと透過してしまうことは生じない。
【００２４】
一方、水素ガスは、水素透過膜Ｄの金属Ａを透過する。すなわち、水素精製器の高圧側から供給される水素分子は、水素透過膜Ｄの表面に露出する金属Ａ若しくはＰｄ、Ｐｔ等のコーティング材表面にて解離し、適度な密度で分散されて相互に接触している多数の金属Ａの粒子内を固溶・拡散して、水素透過膜Ｄの裏面に露出する金属Ａ若しくはコーティング材表面から水素精製器の低圧側へと拡散・放出されて透過する。
【００２５】
また、水素透過膜Ｄの材料（Ａ，Ｂ）の性質にもよるが、金属Ａと物質Ｂの混合比が重要であり、混合比は、固化生成物Ｃ全体ひいては水素透過膜Ｄ全体（金属Ａ＋物質Ｂ）に対して金属Ａ＝３０〜８０ａｔ．％の範囲となるようにすることが好ましい。なぜなら、物質Ｂの混合割合が多過ぎるときは、水素透過膜Ｄ中にて水素透過に効果的に寄与する金属Ａの割合が少なくなり、水素透過速度が低下するのみならず、金属Ａの微粒子同士の適度な接触が少なくなり、これによつても同様に水素透過速度が低下してしまうからである。一方、物質Ｂの混合割合が少な過ぎるときは、物質Ｂによる金属Ａの微粒子を繋ぎ止めておく力が弱くなり、水素透過膜Ｄとするための圧延等の加工が困難になつたり、金属Ａの体積膨張を抑制しながら許容する水素透過膜Ｄの能力が失われてしまうからである。なお、物質Ｂが水素透過性能を有していれば、水素透過膜Ｄの水素透過性能が向上する。
【００２６】
また、水素透過膜Ｄの材料である固化生成物Ｃは、全体に金属Ａ及び物質Ｂが所定の混合比を有する複合体に形成することも可能である。すなわち、金属Ａの粉末状粒子を容器等の所定容積の空間に相互密接状態で充填・充満させ、その空隙の容積を実測により求める。そして、粒子状の金属Ａの空隙の容積に応じた粒子状の物質Ｂを所定量用意する。この物質Ｂの粉末状粒子の量は、金属Ａの間の空隙を完全に埋める体積（実測値）に相当する重量（又は原子数）を密度から算出して実測値として決定する。
【００２７】
その後、上述したように金属Ａ及び物質Ｂの粉末状粒子を均一に混合し、混合体を所定の温度にまで加熱し、物質Ｂのみを溶解させる。この物質Ｂの溶解は、粒子状の金属Ａのみを密接状態で充填した空間と同一容積の空間内において行わせる。これは、シリンダ状容器の中に金属Ａ及び物質Ｂの混合体を入れ、ピストン部材で加圧しながら加熱し、物質Ｂのみを溶解させればよい。これにより、所定容積の空間内において、粒子状の金属Ａの周囲の隙間が溶融状態の物質Ｂによつて満たされる。この粒子状の金属Ａと溶融状態の物質Ｂとの複合体ないし混合体を冷却固化させてインゴットからなる固化生成物Ｃを得ることにより、全体に金属Ａ及び物質Ｂが所定の混合比を有する固化生成物Ｃが得られる。
【００２８】
このような固化生成物Ｃによれば、固化生成物Ｃの全体で所定の混合比を有しているから、物質Ｂのみからなる部分を切除することなく、圧延、切削等の加工により薄膜ないし箔状に形成し、金属Ａ及び物質Ｂの複合体からなる水素透過膜Ｄとすることができる。この水素透過膜Ｄは、金属Ａの粒子同士が良好に密着した状態で、金属Ａ同士の隙間が物質Ｂによつて満たされている。従つて、水素透過膜Ｄの材料（Ａ，Ｂ）、特に物質Ｂの使用量を削減することができる。なお、物質Ｂの金属Ａに対する混合割合は、原子百分率（ａｔ．％）で実測値±１０ａｔ．％の範囲とし、金属Ａの粒子同士が水素透過を行う上で良好に密着した状態とすることができる。
【００２９】
ところで、上記１実施の形態にあつては、金属Ａの融点の方が物質Ｂの融点よりも高いものとしたが、金属Ａの融点の方が物質Ｂの融点よりも低い組み合わせとすることもできる。金属Ａの融点の方が物質Ｂの融点よりも低い場合には、出発原料（金属Ａ，物質Ｂ）は必ずしも粉末状に限られない。例えば、物質Ｂからなるｎｍ〜μｍサイズの連通孔を有する多孔質状の材料隗（例：発泡金属）を作成し、この多孔質状の材料隗をアルゴン、窒素等の不活性ガスの雰囲気中又は真空中で金属Ａの溶融液中に浸し、多孔質状の物質Ｂ内部に金属Ａを含浸させた後、冷却・凝固させることで、上記１実施の形態と同様の構造体（固化生成物Ｃ）を得ることができる。この固化生成物Ｃは、金属Ａが物質Ｂ内に粒子状をなして連続的に分散配置された複合体である。
【００３０】
この複合体（固化生成物Ｃ）は、上記１実施の形態と同様に圧延、切削等の加工により薄膜をなす箔状に形成し、金属Ａ及び物質Ｂの複合体からなる水素透過膜Ｄとする。この水素透過膜Ｄも、水素透過性能に優れる金属Ａの粒子が、表裏両面間に連通する連通孔が形成された多孔質状の物質Ｂの内部に分散配置されて保有され、水素透過膜Ｄの表面から裏面にまで連続している。従つて、この水素透過膜Ｄ中の金属Ａも、物質Ｂに分散材として分散配置され、粒子状の金属Ａが物質Ｂによつて保持されて繋ぎ止められている。
【００３１】
なお、水素透過膜Ｄ内に金属Ａの粒子が独立して存在する場合には、物質Ｂが水素透過性能を有しない限り、水素透過膜Ｄとしての水素透過性能が得られない。従つて、粒子状の金属Ａは、水素透過膜Ｄの表裏両面に適度に露出し、かつ、表面から裏面にまで連続していることが望まれる。
【００３２】
【発明の効果】
以上の説明によつて理解されるように、本発明に係る水素透過膜及びその製造方法によれば、次の効果を奏することができる。
請求項１に係る発明によれば、水素透過性能を有する粒子状の金属が、物質中に分散配置されて、水素透過膜の表面から裏面にまで連続して水素透過の経路を形成しているので、従来材であるＰｄやＰｄ合金と同程度あるいはそれ以上の水素透過性能を有する水素透過膜を得ることができる。また、水素透過性能に優れる粒子状の金属が金属を繋ぎ止めるバインダーの役割をする物質中に分散配置されているので、粒子状の金属の水素固溶に伴う破壊の起きる可能性の少ない水素透過膜を得ることができる。加えて、粒子状の金属及び物質の材料の選択により、従来材料よりはるかに安価な水素透過膜を作製することが可能である。
【００３３】
請求項５に係る発明によれば、固化生成物の全体が所定の混合比を有し、かつ、水素透過性能を有する粒子状の金属の粒子同士が良好に接触した状態にあるから、水素透過膜の材料を有効活用しながら、請求項１に係る発明と同様の効果を奏することができる。
【図面の簡単な説明】
【図１】 本発明の１実施の形態に係る水素透過膜の製造工程を示し、（ａ）は出発金属及び物質を示す図、（ｂ）は固化生成物を示す図、（ｃ）は水素透過膜を支持体と重ね合わせた透過膜構造体を示す図。
【図２】 水素透過膜による水素透過機構を示す説明図。
【符号の説明】
Ａ：金属、Ｂ：物質、Ｃ：固化生成物、Ｄ：水素透過膜、Ｅ：支持体。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen permeable membrane and a method for producing the same, and more particularly to a hydrogen permeable membrane attached to a reformer for producing high purity hydrogen gas and a method for producing the same.
[0002]
[Prior art and problems]
Conventionally, in a membrane reformer type fuel cell that uses city gas, natural gas, oil, etc. as primary energy, after the city gas is led to a membrane reformer that functions as a reformer and hydrogen purifier, the reformed gas is generated. The hydrogen is purified and extracted by utilizing the phenomenon that only the hydrogen gas contained in the reformed gas permeates the hydrogen permeable membrane.
[0003]
Such a hydrogen permeable membrane for a membrane reformer includes palladium (Pd) from the viewpoint of stability in a high temperature environment in the reformer or hydrogen permeation performance with respect to a reformed gas containing impurities such as CO and CO2. ) And Pd-based materials made of a Pd alloy are used.
[0004]
However, Pd is a rare metal that is rarer than gold (Au), and is very expensive and difficult to obtain. Membrane reformers that have been commercialized using such Pd-based materials have a simpler device configuration than conventional reformers that do not use hydrogen permeable membranes, but are not necessarily advantageous from a cost standpoint. It ’s not good. For this reason, as a material for a new hydrogen permeable membrane replacing the Pd-based material, there are many tantalum (Ta), niobium (Nb), so-called hydrogen storage alloy (MH), etc., whose hydrogen solid solution amount is about one digit larger than Pd. It has been proposed (for example, JP-A-2001-170460).
[0005]
Here, as shown in FIG. 2, the hydrogen permeation mechanism by the hydrogen permeable membrane is driven by a pressure difference of hydrogen gas between the front and back surfaces of the permeable membrane D ′ (concentration difference of hydrogen dissolved in the membrane) as a driving force. From the side, the hydrogen molecules H2 dissociate and dissolve in the form of atoms in the film D ′, diffuse and recombine to the low pressure side, and are released again as hydrogen molecules H2.
[0006]
The reformed gas supplied to the high pressure side contains not only hydrogen but also impurity gases such as unreacted hydrocarbon gas (CH 4), CO, and CO 2, which are present in the hydrogen permeable membrane due to restrictions such as atomic size. Does not dissolve. For this reason, only hydrogen gas having a theoretical purity of 100% is released from the low pressure side of the hydrogen permeable membrane. Because of this mechanism, it can be said that the higher the hydrogen solubility and the hydrogen diffusion coefficient, the better the material for the hydrogen permeable membrane, and the lower the hydrogen permeable membrane thickness, the higher the hydrogen permeation rate. I understand that I can do it.
[0007]
As a method for producing such a hydrogen permeable membrane, (1) foil formation by rolling, (2) direct film formation (plating, ion plating, sputtering, etc.) on a porous support (substrate), etc. Has been implemented.
[0008]
To date, only Pd-based materials have been put into practical use as materials for hydrogen permeable membranes, but this material has a very high hydrogen dissociation catalytic action compared to other materials, Since diffusion is fast, it can be said that it is suitable as a material for the hydrogen permeable membrane. However, the Pd-based material is a very expensive material, and its weak point is that the hydrogen solid solution amount is not so large. Against this background, tantalum (Ta), niobium (Nb), or a so-called hydrogen storage alloy (MH), which is cheaper and has a higher hydrogen solubility than Pd, is promising as an alternative material. Yes.
[0009]
However, these alternative materials have a technical problem that deformation occurs due to volume expansion accompanying hydrogen solid solution, and the hydrogen permeable membrane itself often breaks and breaks (particularly in a low temperature region).
[0010]
In the present invention, the problem that the hydrogen permeable membrane is destroyed by a large amount of hydrogen solid solution is that the hydrogen permeable material of the hydrogen permeable membrane is replaced with a foil and dispersed in a substance that is effectively a suitable binder in the form of fine particles. It was made by paying attention to the fact that it can be solved by suppressing cracks caused by volume expansion associated with hydrogen solid solution, by using the Pd substitute material as a hydrogen permeable membrane material, and cracking due to hydrogen solid solution It aims at proposing the hydrogen permeable membrane of the outstanding structure which can avoid the problem of.
[0011]
[Means for Solving the Problems]
The present invention has been made in view of such a conventional technical problem, and the configuration thereof is as follows.
The invention of claim 1 is composed of a composite of a particulate metal A having hydrogen permeation performance and a material B having a ductility made of a metal including an alloy, and the particulate metal A is dispersedly arranged in the material B. The particulate metal A is held together by the substance B, and the proportion of the particulate metal A in the composite is in the range of 30 to 80 at.%, And the particulate metal A is hydrogen. The hydrogen permeable film is characterized in that a hydrogen permeable path is continuously formed from the front surface to the back surface of the permeable film D.
The invention of claim 2 is characterized in that the particulate metal A is composed of a single element of Ta, Nb or V, an alloy containing Ta, Nb or V, and a hydrogen storage alloy, or a mixture thereof. The hydrogen permeable membrane according to claim 1.
The invention of claim 3 is characterized in that the substance B is made of a single element selected from the group consisting of a single element of Cu, Au, Ag, Pt, Fe or Al, or an alloy group containing these elements. This is a hydrogen permeable membrane.
A fourth aspect of the present invention, the particle diameter of the particulate metal A is a hydrogen-permeable membrane according to claim 1, 2 or 3, characterized in that the range of 10Nm～50myuemu.
In the invention of claim 5, particulate metal A having hydrogen permeation performance is closely packed in a predetermined volume of space, the volume of voids in the space is obtained as an actual measurement value, and an amount corresponding to the actual measurement value is obtained. After preparing the particulate substance B having ductility, the particulate metal A and the substance B made of a metal including an alloy are mixed to obtain a mixture, and the mixture is heated to a predetermined temperature to have the same volume. In the space, only the substance B is dissolved, and then cooled and solidified to obtain a solidified product C. The solidified product C is processed into a thin film, and is composed of a composite of particulate metal A and substance B. The particulate metal A is a hydrogen permeable film D in which a hydrogen permeable path is continuously formed from the front surface to the back surface of the hydrogen permeable film D, and the proportion of the particulate metal A in the composite is 30 to 30%. Manufacturing method of hydrogen permeable membrane characterized by being in the range of 80 at.% Is the law.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a manufacturing process of a hydrogen permeable membrane according to an embodiment of the present invention. In FIG. 1A, the symbol A indicates a metal that is a hydrogen permeable material of the hydrogen permeable membrane. This metal A is a metal having a high hydrogen solid solubility and excellent hydrogen permeation performance. For example, the metal A is composed of only Ta (melting point: 2996 ° C.), Nb (melting point: 2415 ° C.), V (melting point: 1735 ° C.), and the like. It consists of one of the elements, alloys containing Ta, Nb, V and the like as main components and hydrogen storage alloys (MH). For example, Ni, Mo, or Co may be added to the alloy containing Ta, Nb, or V as a main component. However, when the combination of the melting point of the metal A is higher than the melting point of the substance B as described later, an alloy containing a single element such as Ta, Nb, or V, Ta, Nb, or V, and a hydrogen storage alloy ( It is also possible to use a mixture in which two or more of (MH) are mixed.
[0013]
The metal A is refined by, for example, performing a hydrogenation treatment a sufficient number of times, and prepared in a particle shape with a diameter of about several nm to 100 μm. Specifically, the particle diameter of the metal A is desirably in the range of 10 nm to 50 μm. Therefore, the metal A is composed of at least one of particles of pure elements such as Ta, Nb, and V, particles of an alloy containing Ta, Nb, and V, and particles of a hydrogen storage alloy. Note that Ta, Nb, and V have higher hydrogen permeation performance than a Pd-based material made of Pd or a Pd alloy.
[0014]
Further, in FIG. 1A, reference numeral B is a substance that serves as a binder for tethering metal A when a hydrogen permeable membrane is formed. For the substance B, particles having the same size as the metal A are prepared. The substance B is a metal including an alloy from the viewpoint of stability in a high temperature environment in the reformer. However, the substance B is a material excellent in ductility and easily elastically deformed, and may have a function as a binder for holding the fine particles of the metal A, and does not necessarily have hydrogen permeability.
[0015]
Specifically, the substance B includes Cu (melting point: 1083 ° C.), Au (melting point: 1063 ° C.), Ag (melting point: about 960 ° C.), Pt (melting point: 1774 ° C.), Fe (melting point: 1535 ° C.), Al It can be set as the particle | grains which consist of 1 type selected from material single elements, such as (melting | fusing point: 660 degreeC), or the alloy group containing these. The material of substance B is shown in Table 1. Since the substance B is a material having excellent ductility necessary for securing the metal A, it is desirable that the elongation at around room temperature is 20% or more, preferably 24% or more.
[0016]
[Table 1]

[0017]
Such metal A particles and substance B particles are prepared. However, the melting point of the metal A is a combination higher than the melting point of the substance B. The powdered particles of the metal A and the substance B are uniformly mixed as shown in FIG. 1B as a predetermined mixing ratio, the mixture is heated to a predetermined temperature, and only the substance B is dissolved. And solidified product C consisting of ingot is obtained. That is, an ingot (solidified product C) is obtained by once solidifying the substance B in the process of heating and cooling and then solidifying again, and the powder particles of the metal A are dispersed and contained in the ingot. Become. The solidified product C has a structure of a composite in which fine metal A is dispersed as a dispersing material inside the cage of the substance B.
[0018]
Here, the mixing ratio of the metal A and the substance B is such that the ratio of the metal A in the composite is in the range of 30 to 80 at.%, That is, the ratio of the metal A in the solidified product C and the hydrogen permeable membrane is 30 to 30%. 80 at. % Range is preferable.
[0019]
The material comprising the solidified product C thus obtained is cut into a thin portion or a foil shape by processing such as rolling and cutting as shown in FIG. A hydrogen permeable membrane D formed of a composite of metal A and substance B is formed. The substance B is excellent in ductility and excellent in machinability. The workability by rolling largely inherits the properties of the substance B material. Therefore, the processing by rolling or cutting of the ingot (solidified product C) can be performed very easily. However, when the hydrogen permeable membrane D is manufactured by rolling the solidified product C, the particle diameter of the metal A is not more than the thickness of the hydrogen permeable membrane D. Like the solidified product C, the hydrogen permeable membrane D thus obtained is composed of a composite or mixture of a metal A having excellent hydrogen permeation performance and a substance B that serves as a binder to hold the metal A together. Of course, the hydrogen permeable membrane D is in a state where there is no vent hole reaching from the front surface to the back surface of the thin film, and the impurity gas does not pass through the hydrogen permeable membrane D.
[0020]
As described above, the mixing ratio of the metal A and the substance B is set so that the ratio of the metal A in the hydrogen permeable membrane D is 30 to 80 at. The reason for setting to be in the range of% is that (1) the fine particles of the metal A are in proper contact with each other in the hydrogen permeable membrane D, and (2) sufficient ductility to obtain the hydrogen permeable membrane D. This is because it is desired to satisfy the two conditions of maintaining the workability.
[0021]
In particular, the metal A particles having excellent hydrogen permeation performance are sufficiently smaller than the film thickness of the hydrogen permeable membrane D, and are continuously in contact from the front surface to the back surface of the hydrogen permeable membrane D, or the metal A particles are hydrogen. It is desirable that the film substantially matches the film thickness of the permeable membrane D, and that many particles of the metal A exist in a penetrating state from the front surface to the back surface of the hydrogen permeable membrane D to form a hydrogen permeable path. That is, when the metal A particles are sufficiently smaller than the film thickness of the hydrogen permeable membrane D, the substance B of the hydrogen permeable membrane D has a porous body shape, but this porous body has communication holes. If it is in the state, the particles of the metal A having excellent hydrogen permeation performance are in a continuous state from the front surface to the back surface of the hydrogen permeable membrane D. When the ratio of metal A to substance B is extremely small, it becomes difficult for metal A particles to come into contact with each other. To do.
[0022]
The hydrogen permeable membrane D is incorporated into a hydrogen purifier of a membrane reformer in a state of being joined to and superposed on a porous support E having communication holes if necessary, and hydrogen gas contained in the generated reformed gas Only hydrogen permeate through the hydrogen permeable membrane D and the support E and are used to purify and take out hydrogen. The support E is, for example, a sintered body of powder or fiber such as ceramics, glass, and stainless steel. If necessary, after coating the front and back surfaces of the hydrogen permeable membrane D with a material (Pd, Pt, etc.) that acts as a hydrogenation catalyst and an antioxidant film by means of sputtering, plating, etc., the hydrogen permeable membrane D And a permeable membrane structure comprising the support E.
[0023]
According to the hydrogen permeable membrane D produced by the above method, when the hydrogen permeation phenomenon occurs, the degree of expansion of the metal A that has been finely pulverized in advance is very small, and the deformation of the metal A is ductile. Absorbed and relaxed by deformation of high substance B. For this reason, a large crack penetrating from the front surface to the back surface of the hydrogen permeable membrane D due to the expansion of the metal A particles due to hydrogen solid solution hardly occurs even after long-term use. Permeation to the low pressure side of the purifier does not occur.
[0024]
On the other hand, the hydrogen gas permeates the metal A of the hydrogen permeable membrane D. That is, the hydrogen molecules supplied from the high-pressure side of the hydrogen purifier are dissociated on the surface of the coating material such as metal A or Pd, Pt exposed on the surface of the hydrogen permeable membrane D, and are dispersed at an appropriate density. A large number of metal A particles in contact are dissolved and diffused, and the metal A or coating material surface exposed on the back surface of the hydrogen permeable membrane D is diffused, released, and transmitted to the low pressure side of the hydrogen purifier. .
[0025]
Further, although depending on the properties of the materials (A, B) of the hydrogen permeable membrane D, the mixing ratio of the metal A and the substance B is important, and the mixing ratio depends on the entire solidified product C and the entire hydrogen permeable membrane D (metal). Metal A = 30-80 at. % Range is preferable. This is because when the mixing ratio of the substance B is too large, the ratio of the metal A that effectively contributes to hydrogen permeation in the hydrogen permeable film D is reduced, and not only the hydrogen permeation rate is lowered but also the fine particles of the metal A This is because there is less moderate contact between them, and this also reduces the hydrogen permeation rate. On the other hand, when the mixing ratio of the substance B is too small, the force for keeping the fine particles of the metal A by the substance B is weakened, and the processing such as rolling for forming the hydrogen permeable film D becomes difficult. This is because the ability of the hydrogen permeable membrane D to be allowed while suppressing the volume expansion of the film is lost. If the substance B has hydrogen permeation performance, the hydrogen permeation performance of the hydrogen permeable membrane D is improved.
[0026]
Further, the solidified product C, which is a material of the hydrogen permeable membrane D, can be formed into a composite in which the metal A and the substance B have a predetermined mixing ratio as a whole. That is, the powdered particles of metal A are filled and filled in a predetermined volume space such as a container in close contact with each other, and the volume of the void is obtained by actual measurement. Then, a predetermined amount of the particulate substance B corresponding to the volume of the void of the particulate metal A is prepared. The amount of the powdery particles of the substance B is determined as a measured value by calculating a weight (or the number of atoms) corresponding to a volume (measured value) that completely fills the gap between the metals A from the density.
[0027]
Thereafter, as described above, the powdered particles of the metal A and the substance B are uniformly mixed, the mixture is heated to a predetermined temperature, and only the substance B is dissolved. The dissolution of the substance B is performed in a space having the same volume as the space filled with only the particulate metal A in a close state. This put a mixture of metals A and substance B in a cylindrical container, and heated under pressure in the piston member, may be dissolved only to a material B. As a result, the gap around the particulate metal A is filled with the molten substance B in a predetermined volume of space. The composite or mixture of the particulate metal A and the molten substance B is cooled and solidified to obtain a solidified product C made of an ingot, whereby the metal A and the substance B have a predetermined mixing ratio as a whole. Solidified product C is obtained.
[0028]
According to such a solidified product C, since the whole solidified product C has a predetermined mixing ratio, the thin film or the thin film or the like can be obtained by processing such as rolling and cutting without excising a portion consisting only of the substance B. A hydrogen permeable membrane D formed of a composite of metal A and substance B can be formed in a foil shape. In the hydrogen permeable membrane D, the metal A particles are in good contact with each other, and the gap between the metals A is filled with the substance B. Accordingly, the amount of the material (A, B) of the hydrogen permeable membrane D, particularly the substance B, can be reduced. In addition, the mixing ratio of the substance B to the metal A is an actually measured value ± 10 at.% In atomic percentage (at.%). % Range, and the metal A particles can be in good contact with each other for hydrogen permeation.
[0029]
By the way, in the first embodiment, the melting point of the metal A is higher than that of the substance B. However, the melting point of the metal A may be lower than the melting point of the substance B. it can. When the melting point of the metal A is lower than the melting point of the substance B, the starting material (metal A, substance B) is not necessarily in the form of powder. For example, a porous material cage (for example, foam metal) made of the substance B and having a communicating hole with a size of nm to μm is prepared, and the porous material cage is placed in an atmosphere of an inert gas such as argon or nitrogen. Alternatively, the structure (solidified product) similar to that of the first embodiment is obtained by immersing in a melt of metal A in a vacuum and impregnating the metal A inside the porous substance B, followed by cooling and solidification. C) can be obtained. The solidified product C is a composite in which the metal A is continuously dispersed in the form of particles in the substance B.
[0030]
This composite (solidified product C) is formed in a foil shape forming a thin film by processing such as rolling and cutting, as in the first embodiment, and a hydrogen permeable membrane D comprising a composite of metal A and substance B. To do. This hydrogen permeable membrane D is also held in such a manner that particles of metal A having excellent hydrogen permeation performance are dispersed and arranged inside a porous substance B in which communication holes communicating between the front and back surfaces are formed. It is continuous from the front side to the back side. Accordingly, the metal A in the hydrogen permeable membrane D is also dispersed and arranged in the substance B as a dispersing material, and the particulate metal A is held and held by the substance B.
[0031]
When the metal A particles are present independently in the hydrogen permeable membrane D, the hydrogen permeable performance as the hydrogen permeable membrane D cannot be obtained unless the substance B has the hydrogen permeable performance. Therefore, it is desired that the particulate metal A is appropriately exposed on both the front and back surfaces of the hydrogen permeable membrane D and is continuous from the front surface to the back surface.
[0032]
【The invention's effect】
As understood from the above description, the hydrogen permeable membrane and the manufacturing method thereof according to the present invention can provide the following effects.
According to the first aspect of the present invention, the particulate metal having hydrogen permeation performance is dispersed and arranged in the substance to form a hydrogen permeation path continuously from the front surface to the back surface of the hydrogen permeation membrane. Therefore, it is possible to obtain a hydrogen permeable membrane having a hydrogen permeation performance equivalent to or higher than that of conventional Pd and Pd alloys. In addition, since the particulate metal with excellent hydrogen permeation performance is dispersed and arranged in the substance that acts as a binder to hold the metal, hydrogen permeation is less likely to occur due to hydrogen dissolution of the particulate metal. A membrane can be obtained. In addition, it is possible to produce a hydrogen permeable membrane that is much cheaper than conventional materials by selecting particulate metal and material materials.
[0033]
According to the fifth aspect of the invention, since the solidified product as a whole has a predetermined mixing ratio and the particulate metal particles having hydrogen permeation performance are in good contact with each other, The effect similar to that of the invention according to claim 1 can be achieved while effectively using the material of the film.
[Brief description of the drawings]
FIG. 1 shows a manufacturing process of a hydrogen permeable membrane according to an embodiment of the present invention, where (a) shows a starting metal and substance, (b) shows a solidified product, and (c) shows hydrogen. The figure which shows the permeable membrane structure which piled up the permeable membrane with the support body.
FIG. 2 is an explanatory view showing a hydrogen permeation mechanism by a hydrogen permeable membrane.
[Explanation of symbols]
A: metal, B: substance, C: solidified product, D: hydrogen permeable membrane, E: support.

Claims (5)

It consists of a composite of a particulate metal (A) having hydrogen permeation performance and a ductile substance (B) made of a metal containing an alloy, and the particulate metal (A) is dispersed in the substance (B). The particulate metal (A) is held together by the substance (B), and the proportion of the particulate metal (A) in the composite is in the range of 30 to 80 at. A hydrogen permeable membrane, wherein the particulate metal (A) continuously forms a hydrogen permeable path from the front surface to the back surface of the hydrogen permeable membrane (D). The particulate metal (A) is composed of a single element of Ta, Nb or V, an alloy containing Ta, Nb or V, and a hydrogen storage alloy, or a mixture thereof. Hydrogen permeable membrane.   3. The hydrogen permeable membrane according to claim 1, wherein the substance (B) is made of one element selected from a single element of Cu, Au, Ag, Pt, Fe, or Al or an alloy group containing these elements. The particle size of the particulate metal (A) is, according to claim 1, 2 or 3 of the hydrogen-permeable membrane, characterized in that the range of 10Nm～50myuemu. Particulate metal (A) having hydrogen permeation performance is filled in a predetermined volume of space in close contact, the volume of voids in the space is obtained as an actual measurement value, and a particulate form having an amount of ductility corresponding to the actual measurement value After preparing the substance (B), the particulate metal (A) and the substance (B) made of a metal containing an alloy are mixed to obtain a mixture, and the mixture is heated to a predetermined temperature to have the same volume. In the space, only the substance (B) is dissolved, and then cooled and solidified to obtain a solidified product (C). The solidified product (C) is processed into a thin film to form a particulate metal (A) And a composite of the substance (B), wherein the particulate metal (A) forms a hydrogen permeable membrane (D) that continuously forms a hydrogen permeable path from the front surface to the back surface of the hydrogen permeable membrane (D). In addition, the ratio of the particulate metal (A) in the composite is in the range of 30 to 80 at.%. A method for producing a hydrogen permeable membrane.

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