JP2012152701A - Hydrogen separation membrane, method of manufacturing the same, and hydrogen separation method - Google Patents

Abstract

The present invention provides a hydrogen separation membrane that can be used in a membrane reactor for steam reforming of hydrocarbons, exhibits no brittleness even at high temperatures, has durability, and has excellent hydrogen permeation performance. Moreover, while providing the manufacturing method of the hydrogen separation membrane, the hydrogen separation method is provided.
A hydrogen separation membrane comprising an alloy thin film mainly composed of palladium, copper, and silver, and the crystal structure of the alloy thin film after heat treatment at 500 ° C. or higher is substantially a body-centered cubic structure. A hydrogen separation membrane characterized by that.
[Selection figure] None

Description

  The present invention relates to a hydrogen separation membrane, a production method thereof, and a hydrogen separation method.

  A thin film of palladium or palladium alloy has a selective hydrogen permeability, and is used as a hydrogen separation membrane by utilizing this characteristic. Typical examples of the palladium alloy thin film include a palladium / silver alloy thin film and a palladium / copper alloy thin film.

  Palladium thin films and palladium / silver alloy thin films have a face-centered cubic structure, and are known to expand when they absorb hydrogen. For this reason, a so-called hydrogen embrittlement phenomenon occurs in which the film expands and contracts due to fluctuations in the hydrogen partial pressure and temperature, causing damage and destruction of the film. When palladium or a palladium alloy is used as a hydrogen separation membrane, generally, the thinner the film thickness, the higher the permeation rate of hydrogen, and the less the amount of noble metal used such as expensive palladium. However, excessive reduction in the thickness of the palladium-based film having a face-centered cubic structure causes the film to be destroyed due to hydrogen embrittlement, resulting in a decrease in film life.

  On the other hand, it is known that a palladium / copper alloy containing about 40 to 50% by weight of copper has a body-centered cubic structure at 300 ° C. (Non-patent Documents 1 and 2). It is known that the palladium-copper alloy having such a body-centered cubic structure absorbs hydrogen significantly less than the above-mentioned face-centered cubic structure alloy (Non-Patent Document 3), and therefore the danger of hydrogen embrittlement. Is expected to be small and is actually known to be highly durable. However, according to the phase diagram of the palladium-copper binary alloy, the face-centered cubic structure and the body-centered cubic structure are obtained at 340 to 550 ° C. in an alloy containing 40% by weight of copper having the highest hydrogen permeation performance among palladium / copper alloys. A crystal structure having a mixed structure is formed, and crystal dislocations are completely generated in a face-centered cubic structure at 550 ° C. or higher (Non-patent Documents 1 and 2). When an alloy containing 40% by weight of copper is actually used as a hydrogen separation membrane, the hydrogen permeation performance at 400 ° C. and 450 ° C. is almost the same, and when it exceeds 450 ° C., the hydrogen permeation performance deteriorates significantly (non-patent document). 4). This is considered to be caused by the appearance of a crystal phase having a face-centered cubic structure at 450 ° C., and when the temperature exceeds 450 ° C., the face-centered cubic structure becomes prominent. Therefore, hydrogen embrittlement due to the face-centered cubic structure and embrittlement due to crystal dislocation are feared even at 450 ° C. Therefore, use of an alloy containing 40% by weight of copper as a hydrogen separation membrane is practically a crystalline phase. Can be said to be preferably performed at 400 ° C. or lower, which is mainly a body-centered cubic structure. In the case of palladium-copper alloys with a copper content of 45 to 48% by weight, the transition temperature from this body-centered cubic structure to the face-centered cubic structure is about 600 ° C., and there is almost no coexistence region between the body-centered cubic structure and the face-centered cubic structure It is known that it does not exist (Non-patent Documents 1 and 2). Therefore, since the palladium-based hydrogen separation membrane having such a composition does not lose the body-centered cubic structure near 600 ° C., there is little risk of hydrogen embrittlement and embrittlement accompanying crystal dislocation in the temperature range of 600 ° C. or lower. Is expected. However, it is known that when the copper content is increased from 40% by weight, the hydrogen permeation rate is significantly reduced even if the crystalline phase of the film has a body-centered cubic structure. In fact, the 47% by weight palladium / copper alloy film maintains a body-centered cubic structure up to around 600 ° C., but its hydrogen permeation performance is only 10-20% compared to the 40% by weight palladium / copper alloy film. It has been reported (Non-Patent Document 5).

  As a method of using a hydrogen separation membrane, there is a membrane reactor technology in which hydrogen production reaction and hydrogen separation are performed in the same reactor. In the production of hydrogen from hydrocarbons, a steam reforming reaction is usually carried out. However, when the reaction is carried out without hydrogen separation, a reaction temperature of 800 ° C. or higher is selected in practice because it escapes from the constraints of chemical equilibrium. On the other hand, when the reaction is carried out while performing hydrogen separation using a membrane reactor, the chemical equilibrium is advantageous to the product side according to Le Chatelier's law, so that the temperature of the reaction can be lowered. However, since the catalyst activity decreases when the reaction temperature is lowered, a large amount of catalyst must be used. To avoid such a situation, the reaction temperature must be at least 500 ° C., preferably 550 ° C. or more. . Here, considering that a hydrogen separation membrane made of a conventionally known palladium / copper alloy is used in a membrane reactor for hydrocarbon steam reforming, for example, 45 wt. A membrane having a high copper content of at least% and having a low hydrogen permeation performance is inevitably used, and as a result, the efficiency of the membrane reactor is greatly reduced and the utility is lost.

  In addition, as a hydrogen separation membrane, there are descriptions in many patent documents that an alloy of a combination of palladium, copper, and silver can be used (for example, Patent Document 1). However, as far as the present inventor is aware, there is no mention of the crystal structure, and there is no precedent specific to an alloy of a combination of palladium, silver and copper.

Binary Alloy Phase Diagrams Second Edition volume 2, 1454-1456 ASMInternational (1990) Mei Li, Zhenmin Du, Cuiping Guo and Changrong Li, “A thermodynamic modeling of the Cu-Pd system”, Computer Coupling of Phase Diagrams and Thermochemistry 32,439-446 (2008) Preeti Kamakoti, Bryan D. Morreale, Michael V. Ciocco, Bret H. Howard, Richard P. Killmeyer, Anthony V. Cugine and David S. Sholl, “Prediction of Hydrogen Flux Through Sulfer-Tolerant Binary AlloyMembranes, Science, 307, 569 -573 (2005) Tatsuya Tsuneki, Yoshinori Shirasaki, Isamu Yasuda, Hydrogen Permeation Performance of Pd-Cu Alloy, Journal of the Japan Institute of Metals, 70: 658-661 (2006) BH Howard, RP Killmeyer, KS Rothenberger, AV Cugini, BDMorreale, RM Enick and F. Bustamante, “Hydrogenpermeance of palladium-copper alloy membranes over a wide range of temperaturesand pressures”, J. Membrane Science, 241, 207-218 ( 2004).

JP2007-69207A

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is that it can be used for a membrane reactor for hydrocarbon steam reforming and does not exhibit brittleness even at high temperatures and has durability. Another object is to provide a hydrogen separation membrane having excellent hydrogen permeation performance. Moreover, while providing the manufacturing method of the hydrogen separation membrane, it aims at providing the hydrogen separation method.

  The present inventor has intensively studied to achieve the above-described object. As a result, when a small amount of silver is added to the palladium / copper alloy, the transition temperature from the body-centered cubic structure to the face-centered cubic structure moves to a high temperature region even when the copper content is small, and even after heating at 550 to 600 ° C. It has been found that a palladium / copper / silver alloy thin film that does not lose the body-centered cubic structure can be formed, and that this thin film can withstand hydrogen separation at 500 to 600 ° C., and the present invention has been completed.

  That is, the object of the present invention is a hydrogen separation membrane comprising an alloy thin film mainly composed of palladium, copper, and silver, and the crystal structure of the alloy thin film after heat treatment at 500 ° C. or higher is substantially body. This is achieved by a hydrogen separation membrane characterized by a centered cubic structure.

  Further, in this hydrogen separation membrane, the copper content in the alloy thin film is 37 wt% to 40 wt%, and the crystal structure of the alloy thin film after heat treatment at least at 500 ° C. is substantially a body-centered cubic structure. It is preferable that

  Moreover, it is preferable that the content of copper in the alloy thin film is 40 wt% to 42 wt%, and the crystal structure of the alloy thin film after the heat treatment at least at 550 ° C. is substantially a body-centered cubic structure.

  Moreover, it is preferable that content of copper in the alloy thin film is 42 wt% to 44 wt%, and the crystal structure of the alloy thin film after the heat treatment at least at 600 ° C. is substantially a body-centered cubic structure.

  Another object of the present invention is a method for producing a hydrogen separation membrane comprising an alloy thin film mainly composed of palladium, copper, and silver, and produces a laminate comprising a palladium-containing thin film, a silver-containing thin film, and a copper-containing thin film. And a step of heat-treating the laminate at 350 ° C. to 600 ° C. to produce an alloy thin film of palladium, copper and silver having a crystal structure substantially having a body-centered cubic structure. Is achieved.

  Further, the object of the present invention is to position the hydrogen-containing mixed gas on one side through the hydrogen separation membrane described above, and set the hydrogen partial pressure on the other side to be equal to or lower than the hydrogen partial pressure on the hydrogen-containing mixed gas side. This is achieved by a method for separating hydrogen from a hydrogen-containing gas mixture.

  According to the present invention, a hydrogen separation membrane that can be used for a membrane reactor for steam reforming of hydrocarbons, exhibits no brittleness even at high temperatures, has durability, and has excellent hydrogen permeation performance, its production method, and hydrogen separation A method can be provided.

2 is a graph showing measurement results of X-ray diffraction patterns of palladium / copper / silver alloy thin films in Example 1. FIG. 6 is a graph showing measurement results of X-ray diffraction patterns of palladium / copper / silver alloy thin films in Example 2. FIG. 6 is a graph showing measurement results of an X-ray diffraction pattern of a palladium / copper alloy thin film in Example 3. FIG. 6 is a graph showing measurement results of an X-ray diffraction pattern of a palladium / copper alloy thin film in Example 4.

Hereinafter, the hydrogen separation membrane of the present invention will be specifically described.
Hydrogen separation membrane and method for producing the same The hydrogen separation membrane of the present invention is an alloy mainly composed of palladium, copper and silver, and preferably contains 37 to 44% by weight, more preferably 38 to 44% by weight of copper. Further, it preferably contains 0.5 to 7% by weight, more preferably 1 to 5% by weight of silver, and the main crystal structure is a body-centered cubic structure even when heated at 500 ° C. or higher. It consists of a characteristic palladium / copper / silver alloy thin film. The hydrogen separation membrane of the present invention has different crystal structure stability depending on the copper content, and the hydrogen separation membrane containing 37 wt% to 40 wt% copper substantially maintains a body-centered cubic structure at least at 500 ° C. The hydrogen separation membrane containing 40 wt% to 42 wt% copper substantially retains the body-centered cubic structure at least at 550 ° C., and the hydrogen separation membrane containing 42 wt% to 44 wt% copper is at least The body-centered cubic structure is substantially retained at 600 ° C. Here, the crystal structure can be specified by measuring the X-ray diffraction pattern. When the hydrogen separation membrane substantially holding the body-centered cubic structure of the present invention is heated, the X-ray diffraction pattern is measured at room temperature. A clear peak due to the body-centered cubic structure of the alloy is detected, and the presence of a peak due to the face-centered cubic structure cannot be clearly detected.

  The preferable film thickness of this thin film is 0.5-30 micrometers, More preferably, it is 1-20 micrometers. If the film thickness is too small, defects increase and the hydrogen selective separation performance deteriorates. If the film thickness is too large, the hydrogen permeation performance deteriorates.

  The hydrogen separation membrane of the present invention may be formed on a support capable of gas diffusion such as porous ceramics and porous sintered metal. Examples of porous ceramics include alumina porous bodies, zirconia porous bodies, ceria porous bodies, zirconia-ceria porous bodies, silica porous bodies, titania porous bodies, yttria-stabilized zirconia porous bodies, mullite porous bodies, and the like. The material of the porous sintered metal is not particularly limited, and for example, stainless steel, hastelloy alloy, inconel alloy, nickel, nickel alloy, titanium, titanium alloy and the like can be used. In order to prevent metal diffusion from the porous sintered metal to the palladium / copper / alloy film, the surface of the porous sintered metal may be oxidized or a diffusion blocking layer such as silver or gold may be formed. . Also, porous ceramics such as alumina porous body, zirconia porous body, ceria porous body, zirconia-ceria porous body, silica porous body, titania porous body, yttria stabilized zirconia porous body, mullite porous body on porous sintered metal A support modified with may be used. In addition, there is no limitation in particular about the shape of a support body, For example, shapes, such as plate shape, a hollow tubular shape, and a bottomed cylindrical shape, are employable.

  The hydrogen separation membrane of the present invention preferably contains 37% to 44% by weight of copper, more preferably 38% to 43% by weight, and preferably 0.5% to 7% by weight of silver, more preferably 1%. It can be produced by rolling a palladium-copper-silver alloy containing 5% by weight to 5% by weight by rolling.

  However, in the case of a thinning method by rolling, there is a limit to thinning, so it is more preferable to form a palladium / copper / silver alloy thin film on some porous support. As a film formation method, for example, a sputtering method such as magnetron sputtering, a chemical vapor deposition method, or a plating method may be used, but among them, the plating method is the simplest and cheapest to form a palladium / copper / silver alloy thin film. Can be membrane.

  In the case of the plating method, when the support surface is a non-conductive substance such as porous ceramics, the metal constituting the palladium / copper / silver alloy thin film may be plated by an electroless plating method. Although it is possible to perform alloy plating for plating a plurality of metal elements by electroless plating, it is difficult to control the composition, and it is preferable to perform the plating step by step. Further, when the support surface is a conductive material, any method of electroless plating or electroplating may be used. From the viewpoint of composition control, it is preferable to plate palladium as the first stage plating. Even if copper or silver is plated in the first stage, the purpose can be achieved by plating the metal constituting the palladium / copper / silver alloy thin film in the latter stage and the subsequent alloying treatment by heating, but copper and silver are palladium. Compared to the above, since it is electrically base, if plating with copper or silver first, substitution plating occurs at the time of plating with a metal containing palladium in the latter stage, making composition control difficult.

  Since the surface of the support becomes conductive by the first stage plating, any method of electroless plating and electroplating can be performed after the second stage. In some cases, displacement plating can also be performed. After the second stage, the metal constituting the palladium / copper / silver alloy thin film may be sequentially plated on the layer formed in the first stage, and then alloyed by heating. Since copper is the most basic in the alloy composition, it is preferable from the viewpoint of composition control to perform plating of a metal containing copper in the final stage.

  Here, in the composition of the plated metal layer, copper is preferably 37 wt% to 44 wt%, more preferably 38 wt% to 44 wt%, and silver is preferably 0.5 wt% to 7 wt%, More preferably, after 1 wt% to 5 wt%, the metal layer is alloyed by heat treatment. In general, copper is easily diffused into palladium by heat treatment, but silver is hardly diffused, and heating at a temperature usually exceeding 600 ° C. is required. However, when the temperature exceeds 600 ° C., the crystal phase of the palladium / copper / silver alloy may have a face-centered cubic structure. To avoid this, once palladium and silver are laminated in the first stage and heated at a temperature exceeding 600 ° C., the silver is diffused into the palladium to form a palladium / silver alloy film, and then in the second stage. It is also possible to stack copper on top and then heat-treat at 600 ° C. or lower to diffuse copper into the palladium / silver alloy to form a palladium / silver / copper alloy. However, the heat treatment at a temperature exceeding 600 ° C. in the first stage has a high risk of deteriorating the metal film, and new defects are generated, leading to deterioration of hydrogen selectivity.

  In order to avoid such a heat treatment at a temperature exceeding 600 ° C., a palladium layer is formed by electroless plating in the first stage, and then palladium / electroplating, which is easier than electroless plating in the second stage, is performed. Silver alloy plating is performed, and copper is plated in the third stage. Here, a known plating bath and plating method may be used for electroless plating and electroplating.

  When the hydrogen separation membrane precursor thus formed is heated preferably at 350 to 600 ° C., more preferably at 450 to 550 ° C., since silver is already diffused in palladium before heating, alloying is performed. Can easily proceed to form a palladium-copper-silver alloy thin film having a body-centered cubic structure. This heat treatment may be performed in a non-oxidizing atmosphere, and can usually be performed by heating in a reducing gas atmosphere or an inert gas atmosphere. As the reducing gas, for example, a reducing gas such as hydrogen or methanol can be used. Examples of the inert gas include helium, nitrogen, argon, water vapor, and the like. Alternatively, it may be performed under vacuum. This processing time may normally be about 5 to 100 hours. In order to remove organic substances adhering to the surface of the hydrogen separation membrane during the treatment, it may be brought into contact with oxygen or a gas containing oxygen.

Hydrogen Separation Method The hydrogen separation membrane of the present invention can be used for separating only hydrogen from a mixed gas containing hydrogen according to a conventional method. For example, a hydrogen-containing mixed gas is positioned on one side separated by the hydrogen separation membrane, one surface of the hydrogen separation membrane is brought into contact with the hydrogen-containing gas, and the hydrogen partial pressure on the other surface side is mixed with the hydrogen-containing mixture. What is necessary is just to be below the hydrogen partial pressure on the gas side. Thus, hydrogen selectively permeates through the hydrogen separation membrane, and only hydrogen on the hydrogen-containing mixed gas side can be moved to the opposite side for separation. The temperature of the hydrogen separation membrane in this case may be within a range in which the body-centered cubic structure of the palladium / copper / silver alloy is maintained, and is usually about 50 to 650 ° C., preferably about 300 to 600 ° C. good. If the temperature is too low, the hydrogen permeation rate is lowered, and if the temperature is too high, the structure changes from a body-centered cubic structure to a face-centered cubic structure, which causes deterioration.

  According to the present invention, a hydrogen separation membrane excellent in durability at high temperatures can be obtained by a relatively simple method. The obtained hydrogen separation membrane can be effectively used particularly for a membrane reactor intended for a reaction requiring a relatively high temperature such as steam reforming of hydrocarbon.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Example 1]
A porous ceramic support with a layer thickness of 30μm and an average pore diameter of 0.1μm manufactured by coating yttria-stabilized zirconia particles on the outer surface of a bottomed cylindrical stainless steel porous sintered metal (diameter 1cm, length 5cm) A palladium layer (palladium-containing thin film) having a thickness of 2.0 μm was formed on the body by electroless plating using a commercially available electroless palladium plating reagent. Subsequently, this palladium layer is immersed in an electroplating solution comprising palladium and silver ammine complexes, and a palladium / silver alloy (silver-containing thin film) is electroplated on the palladium layer, and the palladium / silver alloy is deposited on the palladium layer. Layers were formed. Next, the palladium / silver alloy layer formed on the palladium layer was immersed in an electroplating solution made of a copper ethylenediamine complex to form a copper layer (copper-containing thin film) on the palladium / silver alloy layer.

  A laminate comprising a palladium layer, a palladium / silver alloy layer, and a copper layer is washed and dried, and then heated to 400 ° C. under an argon stream, then heated to 500 ° C. in a hydrogen atmosphere, and then heated to 500 ° C. for 40 hours. Then, a heat treatment was performed to obtain a 6 μm-thick palladium / copper / silver alloy thin film using porous ceramic as a support.

The hydrogen permeation rate (k) of a hydrogen separation membrane made of an alloy containing palladium as a main component generally follows the Sievert law. That is,
k = J / (p1 ^0.5 -p2 ^0.5 )
It becomes. Here, J is the hydrogen permeation flow rate (mmol / s / m ² ), p1 is the inlet-side hydrogen partial pressure (Pa), and p2 is the outlet-side hydrogen partial pressure (Pa).

For gases other than hydrogen, the gas permeation rate (k ′) is generally
k ′ = J ′ / (p3-p4)
And become. Here, J ′ is a gas permeation flow rate (mmol / s / m ² ), p3 is an inlet side gas partial pressure (Pa), and p4 is an outlet side gas partial pressure (Pa).

Therefore, in order to evaluate the performance of the hydrogen separation membrane obtained by the above method, a gas permeation test was conducted in the range of a hydrogen differential pressure of 0 to 2 atm and an argon differential pressure of 0 to 4 atm. A hydrogen permeation rate of ^0.5 / s / m ² / Pa ^{0.5 and} an argon permeation rate of 18 nmol / s / m ² / Pa were obtained.

  After the gas permeation test at 550 ° C., the X-ray diffraction pattern (FIG. 1) measured by cooling the palladium / copper / silver alloy thin film to room temperature is unique to the crystal structure of the body-centered cubic structure. No peak derived from the cubic structure was detected. The average composition of the palladium / copper / silver alloy thin film obtained by ICP emission spectroscopic analysis was 60 wt% palladium, 38 wt% copper, and 1.7 wt% silver. The X-ray diffraction pattern was measured using an X-ray diffractometer (model number: MP6XCE, Cu source) manufactured by Mac Science, and the average composition of the palladium / copper / silver alloy thin film was manufactured by Rigaku / SPECTRO. And an ICP emission analyzer (model number: CIROS-120EOP).

[Example 2]
Using a commercially available electroless palladium plating reagent on the porous ceramic support in the same manner as in Example 1, a 1.8 μm thick palladium layer was formed by electroless plating. Subsequently, in the same manner as in Example 1, a palladium / silver alloy layer was formed on the palladium layer, and a copper layer was formed on the layer.

  After cleaning and drying, the temperature was raised to 400 ° C. under an argon stream, followed by raising the temperature to 500 ° C. under a hydrogen atmosphere, and heat treatment at 500 ° C. for 40 hours to form a porous ceramic support. A 6 μm palladium / copper / silver alloy thin film was obtained.

As a result of conducting a gas permeation test in the same manner as in Example 1 in order to evaluate the performance of the hydrogen separation membrane obtained by the above method, a hydrogen permeation of 0.6 mmol / s / m ² / Pa ^0.5 at 600 ° C. Along with the rate, an argon permeation rate of 1 nmol / s / m ² / Pa was obtained.

  After the gas permeation test at 600 ° C., the X-ray diffraction pattern (FIG. 2) measured by cooling the palladium / copper / silver alloy thin film to room temperature is unique to the crystal structure of the body-centered cubic structure. No peak derived from the cubic structure was detected. The average composition of the palladium / copper / silver alloy thin film obtained by ICP emission spectroscopy was 57 wt% palladium, 41 wt% copper, and 1.7 wt% silver.

[Example 3]
Using a commercially available electroless palladium plating reagent, a palladium layer having a thickness of 1.3 μm was formed by electroless plating on the porous ceramic support in the same manner as in Example 1. Subsequently, in the same manner as in Example 1, a palladium / silver alloy layer was formed on the palladium layer, and a copper layer was formed on the layer.

  After cleaning and drying, the temperature was raised to 400 ° C. under an argon stream, followed by raising the temperature to 500 ° C. under a hydrogen atmosphere, and heat treatment at 500 ° C. for 20 hours to form a porous ceramic as a support. A 4 μm palladium / copper / silver alloy thin film was obtained.

As a result of conducting a gas permeation test in the same manner as in Example 1 in order to evaluate the performance of the hydrogen separation membrane obtained by the above method, a hydrogen permeation of 0.6 mmol / s / m ² / Pa ^0.5 at 600 ° C. Along with the rate, an argon permeation rate of 0.5 nmol / s / m ² / Pa was obtained.

  After the gas permeation test at 600 ° C., the X-ray diffraction pattern (FIG. 3) measured by cooling the palladium / copper / silver alloy thin film to room temperature is unique to the crystal structure of the body-centered cubic structure. No peak derived from the cubic structure was detected. The average composition of the palladium / copper / silver alloy thin film obtained by ICP emission spectroscopy was 56 wt% palladium, 43 wt% copper, and 1.2 wt% silver.

[Example 4]
Using a commercially available electroless palladium plating reagent on the porous ceramic support in the same manner as in Example 1, a palladium layer having a thickness of 0.5 μm was formed by electroless plating. Subsequently, in the same manner as in Example 1, a palladium / silver alloy layer was formed on the palladium layer, and a copper layer was formed on the layer.

  After cleaning and drying, the temperature was raised to 400 ° C. under an argon stream, followed by raising the temperature to 500 ° C. under a hydrogen atmosphere, and heat treatment at 500 ° C. for 40 hours to form a porous ceramic support. A 6 μm palladium / copper / silver alloy thin film was obtained.

As a result of conducting a gas permeation test in the same manner as in Example 1 in order to evaluate the performance of the hydrogen separation membrane obtained by the above method, a hydrogen permeation of 0.6 mmol / s / m ² / Pa ^0.5 at 600 ° C. Along with the rate, an argon permeation rate of 1 nmol / s / m ² / Pa was obtained.

  After the gas permeation test at 600 ° C., the X-ray diffraction pattern (FIG. 4) measured by cooling the palladium / copper / silver alloy thin film to room temperature is unique to the crystal structure of the body-centered cubic structure. No peak derived from the cubic structure was detected. The average composition of the palladium / copper / silver alloy thin film obtained by ICP emission spectroscopy was 51% by weight of palladium, 44% by weight of copper, and 4.6% by weight of silver.

Claims (6)

  A hydrogen separation membrane composed of an alloy thin film mainly composed of palladium, copper and silver, wherein the crystal structure of the alloy thin film after heat treatment at 500 ° C. or higher is substantially a body-centered cubic structure. Hydrogen separation membrane.   The copper content in the alloy thin film is 37 wt% to 40 wt%, and the crystal structure of the alloy thin film after heat treatment at least at 500 ° C is substantially a body-centered cubic structure. Item 2. The hydrogen separation membrane according to Item 1.   The copper content in the alloy thin film is 40 wt% to 42 wt%, and the crystal structure of the alloy thin film after heat treatment at least at 550 ° C is substantially a body-centered cubic structure. Item 2. The hydrogen separation membrane according to Item 1.   The copper content in the alloy thin film is 42 wt% to 44 wt%, and the crystal structure of the alloy thin film after the heat treatment at least at 600 ° C is substantially a body-centered cubic structure. Item 2. The hydrogen separation membrane according to Item 1. A method for producing a hydrogen separation membrane comprising an alloy thin film mainly composed of palladium, copper and silver,
Generating a laminate of a palladium-containing thin film, a silver-containing thin film and a copper-containing thin film;
A method for producing a hydrogen separation membrane, comprising: heat-treating the laminate at 350 ° C. to 600 ° C. to produce an alloy thin film of palladium, copper, and silver having a crystal structure substantially having a body-centered cubic structure. Through the hydrogen separation membrane according to any one of claims 1 to 4, the hydrogen-containing mixed gas is positioned on one side, and the hydrogen partial pressure on the other side is set to be equal to or lower than the hydrogen partial pressure on the hydrogen-containing mixed gas side. A method for separating hydrogen from a hydrogen-containing gas mixture.

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