JP4227907B2 - Pd alloy hydrogen separation membrane material - Google Patents

Description

  The present invention relates to a Pd alloy hydrogen separation membrane material. In particular, the present invention relates to a Pd alloy hydrogen separation membrane material that has high hydrogen permeation performance that exceeds conventional limits and is stable for a long period of time.

  Conventionally, by utilizing the fact that a certain kind of metal film has an overwhelmingly high hydrogen permeation rate compared to other gas components, hydrogen is selectively permeated from a mixed gas containing hydrogen, and high purity is achieved. Hydrogen production methods for obtaining hydrogen have been researched and developed, and some have been put into practical use.

  As the metal film material, a Pd alloy has been put into practical use. This is because the Pd alloy has the property of selectively dissolving and permeating hydrogen, and is less prone to hydrogen embrittlement (formation of hydride and embrittlement), and is excellent in oxidation resistance, carburization, and nitridation, This is because it has a feature that it can be used stably for a long time. On the other hand, Pd is a noble metal and a strategic substance. Therefore, Pd is already expensive, and if a large amount of consumption is expected, there is a possibility that it will rise. Therefore, a method of adding an additive element has been proposed for the purpose of substituting Pd with another element and reducing the amount of Pd used by improving the hydrogen permeation performance of the Pd alloy.

  Patent Document 1 proposes that a ternary alloy film in which Ag, Y, Gd, Lu, or the like is added to Pd has excellent permeation performance. Moreover, in patent document 2 and patent document 3, hydrogen permeation performance improves 4 to 8 times by adding one kind of additive element in Sm, Ce, Yb, Tb, Dy, Ho, and Er to Pd. Propose to do.

  On the other hand, it has been clarified that the addition of 3A group elements such as Sc, Y, Eu, Ho, Yb, and Lu and rare earth elements to Pd increases the lattice constant of the Pd alloy solid solution. Furthermore, Non-Patent Document 1 reports that the lattice constant of Pd to which an alloy is added and the hydrogen permeation performance are in a substantially linear relationship, and the hydrogen permeation performance increases as the lattice constant increases.

In summary, it can be arranged that the addition of a 3A group element and a rare earth element to Pd increases the lattice constant of the Pd alloy and improves the hydrogen permeation performance. In the examples and non-patent documents in these patent documents, the upper limit of the amount of alloy added is slightly different depending on the kind of the additive element, but is at most 8 atomic%. This improves the addition of additive element more than that, beyond the limits Pd can solute, Pd _x M _y (M is additive element) is the second phase intermetallic compound is precipitated, the hydrogen permeability is higher It is said not to. From the examples in the above-mentioned patent documents and non-patent documents, the hydrogen permeation performance improvement of the Pd alloy by the additive element is within 4 times that of Pd to which no alloy is added, which can be said to be the limit of this method.
JP-A-11-99323 JP 2001-46845 A JP 2001-131653 A Seki et al., The Japan Institute of Metals Spring Meeting Performance Overview (2001), p147

  The present invention improves the hydrogen permeation performance of a Pd alloy and increases its stability and reduces the amount of Pd used in a Pd alloy hydrogen separation membrane material that obtains high purity hydrogen by permeating only hydrogen from a hydrogen mixed gas. Aimed at

The present invention provides a hydrogen separation membrane material that selectively permeates hydrogen from a hydrogen mixed gas to obtain high-purity hydrogen, wherein Pd is a base metal, and one or more types selected from group 3a elements and rare earth elements in the periodic table The element is an additive element M, the concentration of the additive element M is 5 to 20 atomic%, and at least the Pd alloy solid solution as the parent phase is supersaturated in a temperature range of 300 ° C. to 700 ° C. a Pd alloy hydrogen separation membrane material formed as a solid solution, wherein if the concentration of the additive element M is greater than or equal to the maximum solid solubility limit concentration of Pd solid solution, Pd solid solution Pd concentration is highest Pd _x M _y intermetallics a eutectic temperature T lower than _E ° C. with, (T _E -450) subjected to a heat treatment at a temperature within the range of more than ° C., when the concentration of the additive element M is less than or equal to the maximum solid solubility limit concentration of Pd solid solution Includes the solidus temperature of the Pd solid solution A full, (T _E -450) subjected to a heat treatment at a temperature within the range of more than ° C., then provides Pd alloy hydrogen separation membrane material obtained by quenching. The maximum solid solution limit concentration (Ms _max ) of the additive element M satisfies 5 ≦ Ms _max ≦ 20 (unit: atomic%). “Rapid cooling” means that an alloy at a solution treatment temperature is cooled to about 20 ° C. within about 10 seconds, for example, by contacting with water at room temperature.

  It is preferable that the Pd alloy hydrogen separation membrane material has a single phase structure of a Pd alloy solid solution.

  Alternatively, the Pd alloy hydrogen separation membrane material may be a multiphase structure composed of a parent phase of a Pd alloy solid solution and an intermetallic compound.

  The one or more elements M selected from the group 3a elements and rare earth elements in the periodic table are preferably Y, Ce, Sm, Gd, Dy, Yb, and Lu.

According to still another aspect of the present invention, there is provided a method for producing a Pd alloy hydrogen separation membrane material, wherein one or more kinds of additions selected from Pd as a base metal, a group 3a element in the periodic table, and a rare earth element are added. In the step of mixing the element M so that the concentration of the additive element M is 5 to 20 atomic%, and when the mixed metal has the M concentration equal to or higher than the maximum solid solution limit concentration of the Pd solid solution, and Pd solid solution, a eutectic temperature T lower than _E ° C. with Pd concentration is highest Pd _x M _y intermetallic compound, (T _E -450) at a temperature in the range of more than ° C., the M concentration Pd solid solution In the case where the concentration is less than the maximum solid solution limit concentration, the heat treatment is performed at a temperature lower than the solidus temperature of the Pd solid solution and in the range of (T _E -450) ° C. or more, and the heat treated metal Quenching.

  According to the present invention, a single-phase structure of a Pd alloy solid solution as a parent phase can be obtained by the Pd alloy hydrogen separation membrane material and the manufacturing method thereof, and the hydrogen permeation performance is further improved as compared with the conventional one. In addition, the material whose additive concentration is higher than the solid solution limit has a multiphase structure composed of a matrix and an intermetallic compound of a Pd alloy solid solution, and is supersaturated at the operating temperature in a fuel cell device or the like. Hydrogen permeation performance is improved. Even in the supersaturated Pd alloy hydrogen separation membrane material, it took time to deposit and grow an intermetallic compound, and as a supersaturated solid solution, high hydrogen permeation performance could be maintained for a long time.

  As an effect of the present invention, by increasing the solution treatment temperature to increase the amount of alloy added elements, or by adding an alloy beyond the solid solution limit, high hydrogen permeation performance exceeding the conventional limit can be achieved. It became possible to get.

  The Pd alloy hydrogen separation membrane material according to the embodiment of the present invention includes the base metal Pd and the additive element M. The additive element M can be one or more elements selected from the group 3a elements such as Sc and Y and rare earth elements. In particular, it is preferable to use Y, Ce, Sm, Gd, Dy, Yb, or Lu as the additive element M. This is because the effect of improving the hydrogen permeation performance is basically the same for the group 3a and rare earth elements, but the effect of improving the hydrogen permeation performance is somewhat superior. When the additive element M is two or more, it is preferable to use a combination of two or more elements selected from Y, Ce, Sm, Gd, Dy, Yb, and Lu. This is because the same effect as the Pd-M binary alloy can be obtained.

  The addition concentration of the additive element is not constant because the solid solubility limit of Pd varies depending on the element, but it is preferable to set it within the range of 5 to 20 atomic%. If the amount is less than 5 atomic%, the effect of improving the hydrogen permeation performance is not sufficient. If the amount is more than 20 atomic%, the formation of an intermetallic compound is remarkable, which causes a problem in workability. The addition concentration of the additive element M can be determined from the solid solution limit concentration (atomic%) of the additive element M in the base metal Pd at the solution treatment temperature described in detail below. Specifically, the addition concentration of the additive element M is the same as the concentration limit (atomic%) of the additive element M in the base metal Pd at the solution treatment temperature of the Pd alloy hydrogen separation membrane material. It can be within a concentration range of 1 to 8 atomic% higher.

  In addition to the base metal Pd and the additive element M, the Pd alloy hydrogen separation membrane material usually contains an element inevitably mixed.

The structure of the Pd alloy hydrogen separation membrane material may be a single phase structure of a Pd alloy solid solution as a matrix. In addition to the single phase structure of such a Pd alloy solid solution, may be one Pd _x M _y is a second phase is precipitated. Here, Pd _x M _y represents a Pd _x M _y intermetallic compounds most Pd concentration higher side on the diagram a state of Pd-M alloy. In the case of using the Group 3a element or rare earth element as described above as an additive element M is Pd _x M _y intermetallic compound is often the Pd ₃ M _1, which are not limited.

  The Pd alloy hydrogen separation membrane material according to the present embodiment is in a supersaturated solid solution state in the range of 700 to 300 ° C., which is a general use temperature used as a hydrogen separation membrane.

  Next, the Pd alloy hydrogen separation membrane material according to the present invention will be described from the aspect of the production method. The Pd alloy hydrogen separation membrane material according to the present embodiment is obtained by mixing Pd, which is a base metal, and the additive element M at a predetermined concentration, performing a solid solution treatment, and rapidly cooling.

  Both the base metal Pd and the additive element M preferably have a purity of 99.9% or more. The additive element M may be used alone or in combination of two or more.

  In general, “solid solution treatment” is defined by adding an additive element having a concentration within the solid solution limit to a base metal to obtain a single phase structure of only the base metal matrix phase. However, in the present invention, the concentration of the additive element M may be equal to or higher than the solid solution limit concentration, and such a heat treatment is represented as a solid solution treatment even if the second phase which is an intermetallic compound is precipitated. I will do it.

The solution treatment temperature is set as follows. In Pd-M alloy, when M concentration is maximum solubility limit concentration Ms _max over Pd solid solution is less than the eutectic temperature T _E of Pd solid solution Pd concentration is highest Pd _x M _y intermetallics Thus, a temperature in the range of (T _E −450) ° C. or higher, which is 450 ° C. lower than T _E , is set as a solution treatment temperature. On the other hand, M concentration in the case of less than the maximum solid solubility limit concentration Ms _max of Pd solid solution is a solidus temperature below the Pd solid solution, Pd solid solution Pd concentration is the highest Pd _x M _y intermetallics A temperature in the range of (T _E -450) ° C. or higher which is 450 ° C. lower than the eutectic temperature T _E is defined as a solution treatment temperature.

The Pd-rich side of the Pd-M alloy phase diagram is generally as shown in FIG. 1, although the composition and temperature vary depending on the type of M. Temperature to increase solid solubility the most additive element in Pd solid solution, Pd solid solution Pd concentration is at eutectic temperature T _E of the highest Pd _x M _y intermetallic compound. Therefore, in order to obtain a Pd solid solution to which a high concentration of the additive element M is added, it is desirable to perform the solution treatment at a temperature close to T _E. However, in FIG. 1, at a temperature higher than the shaded area, partial melting may occur and the alloy material may be greatly deformed. Therefore, it is desirable to perform the solution treatment at a temperature in the shaded area in the drawing. In addition, when the solution treatment is performed at a temperature lower than (T _E −450) ° C., the concentration of the additive element M in the matrix Pd alloy solid solution is lowered, so that a sufficient hydrogen permeation performance improvement effect can be achieved. There is a problem that it cannot be obtained. Therefore, it is desirable to perform the solution treatment at a temperature higher than (T _E −450) ° C. Among the shaded temperature range, a temperature range of (T _E −20) ° C. to (T _E −100) ° C. is particularly preferable. This is because the hydrogen permeation performance is the best because the concentration of the additive element M in the Pd alloy solid solution as the matrix is the highest.

  In the present embodiment, the method for determining the solution treatment temperature using the phase diagram of the Pd-M binary alloy has been described. However, in the embodiment including two or more kinds of additive elements M, the state of the multi-component alloy is similarly described. The solution treatment temperature can be determined from the figure. It is within the scope of the present invention that a person skilled in the art can appropriately select two or more elements from the additive element M disclosed in the present application, create a phase diagram, and determine the solution treatment temperature. It is.

  The solution treatment time of the Pd alloy hydrogen separation membrane material of the present invention can be 10 minutes to 1 hour. Such a solution treatment can be carried out by a person skilled in the art using an apparatus that is usually used. A Pd alloy hydrogen separation membrane material can be obtained by performing a solution treatment under the temperature and time conditions described above and then cooling with water. The obtained Pd alloy hydrogen separation membrane material is usually an ingot material, and a Pd alloy hydrogen separation membrane can be produced by cutting a plate material from this and rolling it to a desired thickness.

The present inventors have studied to overcome the limitations of Pd lattice constant expansion and hydrogen permeation performance improvement by adding alloys, and as a result of experimental considerations, have found the above-described further method for improving hydrogen permeation performance It is. That is, the present inventors paid attention to the fact that the additive element solid solution limit of Pd increases with temperature. Pd subjected to solution treatment at a high temperature just below the temperature corresponding to the eutectic temperature T _E in the phase diagram closest to the alloy composition, with the addition of an additive element having a solid solution limit concentration at that temperature. The alloy can dissolve the additive element at the highest concentration. And the lattice constant of the Pd alloy solid solution manufactured in this way becomes the largest. This maximizes the hydrogen permeation performance.

  On the other hand, in order to efficiently produce high-purity hydrogen, for example, a general operating temperature used as a hydrogen separation membrane for separating and extracting only hydrogen from a hydrogen mixed gas atmosphere by, for example, steam reforming of methane gas is in the range of 700 to 300 ° C. It is. As described above, the Pd alloy solid solution subjected to the solid solution treatment immediately below the eutectic temperature is in a supersaturated solid solution state because the solid solution limit decreases in the operating temperature range. However, in the operating temperature range, it took a considerable amount of time for the intermetallic compound to precipitate and the lattice constant to decrease, and in practice it was revealed that high hydrogen permeation performance was maintained for a long time as a supersaturated solid solution. .

  In the present invention, the Pd base metal dissolves the additive element, and the alloy solution is subjected to a solution treatment at a high temperature within the range showing the single-phase structure of the solid solution Pd. The transmission performance is to be obtained. On the other hand, the concentration of the added element is further increased, an element having a concentration higher than the solid solution limit is added, and the second phase which is an intermetallic compound remains after the solution treatment, but the matrix phase (parent phase) is It has also been clarified that a Pd alloy in a state where an alloy having a solid solution limit concentration is in a solid solution exhibits high hydrogen permeation performance as well.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the present invention.
[Example 1]

In Example 1 of the present invention, Ce, Gd, and Lu were selected from Y and rare earth elements as the additive element M. As a result of pre-examined alloy phase diagram and send the Pd-M2 binary alloy system, Pd concentration (all Pd ₃ M ₁ is selected alloys based) and formed by the meeting of a Pd highest intermetallic Pd _x M _y The eutectic temperature T _E and the solid solution limit concentration of each additive element in Pd were estimated as follows. The composition of the alloy was expressed as “Pd−x% M”. Here, “x%” means atomic% of the additive element M in the alloy.

  Therefore, a Pd alloy ingot was melted by arc melting in Ar gas using Pd powder having a purity of 99.95% or more and Y, Ce, Gd or Lu powder having a purity of 99.9% or more. Pd alloys are Pd-12% Y, Pd-14% Y, Pd-13% Ce, Pd-15% Ce, Pd-12% Gd, Pd-14% Gd and Pd-14% Lu, Pd-16% A product having the composition of Lu was produced. However, in this embodiment, these alloys contain impurity elements inevitably mixed in addition to Pd and additive elements. The composition of these alloys is such that each additive element M has a composition corresponding to the solid solution limit concentration at a solution treatment temperature of 1150 ° C. and a composition in which the additive element M is 2 atomic% higher than the solid solution limit concentration. Selected.

Next, using these Pd alloy ingot samples, solution treatment was performed in an Ar atmosphere furnace. The solution treatment temperature was 1150 ° C. This temperature is the eutectic temperature T 20 to 80 ° C. lower temperature than _E between the Pd solid solution and Pd ₃ M intermetallic compounds each alloy system. Each Pd alloy ingot was heated in an Ar atmosphere for 60 minutes and then cooled with water to obtain a Pd alloy hydrogen separation membrane material.

[Comparative example]
Next, as a comparative test, Pd, Pd-10% Y, Pd-11% Ce, Pd-10% Gd, and Pd-12% Lu alloy were similarly melted and subjected to solid solution treatment at 500 ° C. to obtain a Pd alloy. A hydrogen separation membrane material was obtained.

[Evaluation and structure observation of hydrogen permeation performance]
A plate material was cut out from the obtained Pd alloy hydrogen separation membrane material (originally an ingot material) of the example and the comparative example, rolled to a thickness of 0.5 mm, and a disk-shaped sample having a diameter of 30 mm was manufactured, and hydrogen permeation was performed. A performance evaluation test was conducted. The hydrogen permeation performance was measured using hydrogen gas with a purity of 99.999%, temperature of 500 ° C., primary side pressure of 0.3 MPa, and secondary side pressure of 0.1 MPa. Evaluation was performed by calculating a normalized hydrogen permeation coefficient in consideration of thickness and front and back hydrogen pressure. At that time, He gas having the same pressure difference was introduced to confirm that there was no leakage. Moreover, the structure of the rolled material was observed using an optical microscope. Table 2 summarizes the hydrogen permeation performance and the structure observation results for the samples of Examples and Comparative Examples.

  As shown in Table 2, the Pd alloy materials having the above-mentioned eight kinds of compositions subjected to the solid solution treatment at 1150 ° C. have a hydrogen permeation performance that is more than four times that of the Pd material to which no alloy is added, which is a conventional limit. showed that. In particular, the hydrogen permeation performance of Pd-14% Y, Pd-15% Ce, Pd-14% Gd, and Pd-16% Lu alloy pressurized material having a composition exceeding the solid solution limit is the solid solution at 1150 ° C. of each additive element. The hydrogen permeation performance was higher than that of the Pd alloy material having the composition of the solubility limit concentration.

As a result of structural observation, the solid solution limit compositions Pd-12% Y, Pd-13% Ce, Pd-12% Gd and Pd-14% Lu alloy materials showed a single-phase structure. On the other hand, Pd-14% Y, Pd-15% Ce, Pd-14% Gd, and Pd-16% Lu alloy materials having compositions exceeding the solid solution limit have some Pd ₃ M ₁ (M is Y, Ce, Gd). Lu) It exhibited a two-phase structure in which precipitation of intermetallic compounds was observed. Since the latter group has better hydrogen permeation performance than the former group, it is presumed that the second phase precipitation has influenced the hydrogen permeation performance.

[Thermal stability evaluation of hydrogen permeation performance]
Next, the heat of hydrogen permeation performance was measured for four types of rolled alloy samples of Pd-14% Y, Pd-15% Ce, Pd-14% Gd and Pd-16% Lu that showed particularly excellent hydrogen permeation performance. Stability was evaluated. The sample manufactured as described above was subjected to heat treatment at 700 ° C. for 500 hours or 600 ° C. for 2000 hours using an Ar atmosphere furnace, and changes in hydrogen permeation performance were investigated. The hydrogen permeation performance was measured by the method described above. The results are shown in Table 3.

  All the materials exhibited 98% or more of hydrogen permeation performance after heating at 700 ° C. for 500 hours, and the performance degradation was within 2%. Moreover, the hydrogen permeation performance after heating at 600 ° C. for 2000 hours showed 99% or more before heating, and the decrease in hydrogen permeation performance was within 1%.

  From the above, at a use temperature of 700 ° C. or less, which is a general temperature when using a Pd alloy as a hydrogen separation membrane, the Pd-M alloy membrane material having a supersaturated composition exhibits excellent hydrogen permeation performance, It has become clear that the hydrogen permeation performance is stable and can be used for a sufficiently long period of time. This is because, at 700 ° C. or lower, diffusion of Pd and additive elements is slow, and it takes time for precipitation and growth of intermetallic compounds, and local precipitation and growth of intermetallic compounds is immediately related to the overall hydrogen permeation performance. It is thought that it does not have a big influence on

[Example 2]
Samples having different alloy compositions and solution treatment temperatures were prepared in the same manner as in Example 1, and the hydrogen permeation performance was evaluated. Here, the solution treatment temperature was carried out at 800 ° C. four hundred thirty to three hundred and seventy a ° C. lower temperature than the eutectic temperature T _E between the Pd solid solution and Pd ₃ M intermetallic compound in the alloy system.

  The additive element M is the same as that in Example 1, and a Pd powder having a purity of 99.95% or more and Y, Ce, Gd, and Lu powders having a purity of 99.9% or more are used in an Ar gas. It was melted by arc melting. The composition of the manufactured Pd alloy ingot was Pd-11% Y, Pd-13% Y, Pd-12% Ce, Pd-14% Ce, Pd-11% Gd, Pd-13% Gd and Pd-13% Lu. , Pd-15% Lu. However, these alloys contain impurity elements inevitably mixed in addition to Pd and additive elements. The compositions of these alloys were selected so that the additive element M had a composition corresponding to the solid solution limit concentration at 800 ° C. and a composition in which the additive element M was 2 atomic% higher than the solid solution limit concentration. Next, using these ingot samples, a solid solution treatment was performed in an Ar atmosphere furnace at a temperature of 800 ° C. and a maintenance time of 60 minutes, followed by water cooling to obtain a Pd alloy hydrogen separation membrane material.

[Evaluation and structure observation of hydrogen permeation performance]
The obtained Pd alloy hydrogen separation membrane material was processed into a disk shape, a sample was produced, and the hydrogen permeation performance was evaluated in the same manner as in Example 1. Moreover, the structure | tissue observation of the processed material was performed using the optical microscope. The results are summarized in Table 4. The Pd alloy materials having the above eight compositions subjected to the solution treatment at 800 ° C. showed higher hydrogen permeation performance than the comparative materials shown in Table 1.

[Thermal stability evaluation of hydrogen permeation performance]
Thermal stability of hydrogen permeation performance was evaluated for four types of rolled alloy samples of Pd-13% Y, Pd-14% Ce, Pd-13% Gd, and Pd-15% Lu. In the same manner as in Example 1, using an Ar atmosphere furnace, the sample was heat-treated at 700 ° C. for 500 hours or 600 ° C. for 2000 hours, and the change in hydrogen permeation performance was investigated. The results are shown in Table 5. The hydrogen permeation performance was measured as described above.

  All the materials exhibited 99% or more of hydrogen permeation performance after heating at 700 ° C. for 500 hours, and the performance degradation was within 1%. Further, the hydrogen permeation performance after heating at 600 ° C. for 2000 hours also showed 99% or more before the heating, and the hydrogen permeation performance decreased within 1%. From the above, at a use temperature of 700 ° C. or less, which is a general temperature used as a hydrogen separation membrane, the Pd-M alloy membrane material having a supersaturated composition exhibits excellent hydrogen permeation performance and stable performance. It was revealed that it can be used for a long time, sufficiently practical.

A method for producing pure hydrogen from steam reforming of methane gas or the like using a metal film that selectively permeates hydrogen, such as a Pd alloy film, is generally performed at a temperature of 700 ° C. to 300 ° C. Conventionally, it has been clarified that hydrogen permeation performance is improved by adding an element selected from Group 3a and rare earth elements to Pd. However, the amount of the alloy added was substantially 8 atomic% or less, although it was slightly different depending on the added element. This was to keep the solid solution limit or less at the use temperature. On the other hand, the solid solution limit of the additive element to Pd tends to increase with temperature, and a higher concentration additive element can be added by performing the solution treatment at a high temperature. Here, Y, Ce, Gd, and Lu were selected as additive elements, and an alloy to which a high concentration additive element of 12 to 14 atomic% was added was melted. These alloy ingots were subjected to solution treatment at 20 to 80 ° C. lower 1150 ° C. Nitaishi eutectic temperature of the most Pd concentration is high Pd _x M _y intermetallic compound and solid solution Pd of each Pd-M2 binary alloy. As a result, a solid solution Pd single phase structure was obtained, and the hydrogen permeation performance was further improved as compared with the conventional one.

  It was also found that the hydrogen permeation performance was further improved when the addition concentration was increased beyond the solid solution limit. Here, 14 to 16 atomic% of the above four types of additive elements were added, and a solution treatment was performed at 1150 ° C. In any alloy system, since the solid solution limit concentration was exceeded, a completely solid solution single-phase structure was not obtained, and a two-phase structure in which an intermetallic compound was precipitated was exhibited. The Pd alloy with the alloy added exceeding the solid solution limit has a better hydrogen permeation performance than the Pd alloy with the solid solution limit concentration added. This is presumed to have been affected. On the other hand, although the material added with the additive element at such a high concentration is supersaturated at the use temperature, it takes time to precipitate and grow an intermetallic compound, and practically as a supersaturated solid solution. High hydrogen permeation performance was maintained for a long time.

  Further, the same four types of binary alloys as Pd—Y, Pd—Ce, Pd—Gd, and Pd—Lu as described above, the alloy addition concentration is in the range of 11 to 15 atomic%, and the solution treatment temperature is 800 ° C. The same test was carried out even in the case of, and it was confirmed that high hydrogen permeation performance and long-term stability were obtained.

  As examples of utilization of the Pd alloy hydrogen separation membrane material of the present invention, a hydrogen supply device that supplies raw hydrogen to a fuel cell by selectively extracting only high-purity hydrogen, and a ground that supplies hydrogen to a fuel cell vehicle Examples include a hydrogen station as equipment, a hydrogen purifier for producing high-purity hydrogen used in a semiconductor factory, and the like.

It is a figure which shows the solution treatment temperature range in manufacture of Pd alloy hydrogen separation membrane material.

Claims (4)

In a hydrogen separation membrane material that selectively permeates hydrogen from a hydrogen mixed gas to obtain high purity hydrogen,
Pd is a base metal, one or more elements selected from Group 3a elements and rare earth elements of the periodic table are added elements M, and the concentration of the added elements M is 5 to 20 atomic%, and is at least a parent phase The Pd alloy solid solution is a Pd alloy hydrogen separation membrane material made of a Pd alloy in which the additive element M is dissolved in a supersaturated concentration in a temperature range of 300 ° C. to 700 ° C.
Wherein when the concentration of the additive element M is greater than or equal to the maximum solid solubility limit concentration of Pd solid solution, a eutectic temperature T lower than _E ° C. with Pd solid solution Pd concentration is highest Pd _x M _y intermetallic compound, (T _E- 450) When heat treatment is performed at a temperature in the range of at least C, and when the concentration of the additive element M is less than or equal to the maximum solid solution limit concentration of the Pd solid solution, it is less than the solidus temperature of the Pd solid solution, (T _E -450) A Pd alloy hydrogen separation membrane material obtained by performing a heat treatment at a temperature in the range of not lower than ° C and then cooling with water .   The Pd alloy hydrogen separation membrane material according to claim 1, wherein the Pd alloy hydrogen separation membrane material has a single-phase structure of a Pd alloy solid solution.   2. The Pd alloy hydrogen separation membrane material according to claim 1, wherein the Pd alloy hydrogen separation membrane material has a multiphase structure composed of a parent phase of a Pd alloy solid solution and an intermetallic compound. Mixing Pd serving as a base metal with one or more additive elements M selected from Group 3a elements and rare earth elements of the periodic table so that the concentration of the additive element M is 5 to 20 atomic%; ,
Mixed metal,
Wherein when M concentration is greater than or equal to the maximum solid solubility limit concentration of Pd solid solution, and Pd solid solution, a eutectic temperature T lower than _E ° C. with Pd concentration is highest Pd _x M _y intermetallic compound, (T _E- 450) at a temperature in the range of not less than ° C,
Wherein when M concentration is less than or equal to the maximum solid solubility limit concentration of Pd solid solution is a solidus temperature below the Pd solid solution, at a temperature in the range of (T _E -450) ℃ or higher,
A heat treatment step;
A method for producing a Pd alloy hydrogen separation membrane material comprising a Pd alloy, comprising the step of water-cooling the heat-treated metal.

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