JPH10297906A - Hydrogen separation membrane and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the permeation performances, hydrogen embrittlement and high- temperature resistances of a hydrogen-permeable alloy membrane by coating the surface of a metallic porous support such as a metallic nonwoven fabric with a columnar structural membrane to a preferably thickness according to a vacuum deposition method and further coating the surface thereof with a membrane capable of selectively permeating only hydrogen such as Pd to a specified thickness thereon. SOLUTION: A columnar structure, having pores with <=0.1 μm pore diameter and providing an intermediate support is formed into a membrane having 40-300 μm thickness on a metallic porous material because the minimization of the membrane thickness of a hydrogen-permeable membrane composed of a metal such as Pd results in an improvement in performances of the high-purity hydrogen separation membrane. A membrane capable of selectively permeating the only hydrogen such as Pd is then formed thereon to 1-20 μm thickness thereon. Thereby, the membrane formation having the minimum membrane thickness and practicality without membrane defects can be carried out. For example, a material for the columnar structure such as Ni is formed on a metallic nonwoven fabric (having <=0.1 μm pore diameter) by using Ar as an introduction gas at 5×10<-4> Torr vacuum degree and 10 μm/min membrane formation rate to form a columnar structural membrane 2 having 40 μm membrane thickness and a hydrogen-permeable membrane 3 having 5 μm thickness is then vacuum deposited thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen separation membrane and a method for manufacturing the same, and more particularly, to a hydrogen separation membrane applied to a high-purity hydrogen gas production apparatus and a purification apparatus and a method for producing the same.

[0002]

2. Description of the Related Art As a means for separating and recovering high-purity hydrogen gas from a hydrogen mixed gas, a method using a metal membrane that selectively transmits hydrogen has already been put to practical use. This method
For example, it utilizes the fact that a palladium (Pd) -based metal film exhibits an extremely high hydrogen permselectivity, and is currently used for the separation and purification of hydrogen in semiconductor manufacturing. The hydrogen selective permeation phenomenon exhibited by Pd and its alloy film is that the hydrogen molecules in the hydrogen mixed gas are adsorbed by the Pd film to be in an atomic state, further ionized, diffused to the opposite side of the film, recombined, and hydrogen It is supposed to happen to become gas. Industrially, the pressure on the surface of the membrane that is in contact with the gas mixture is slightly higher than the pressure on the opposite side of the membrane, adding a driving force for hydrogen permeation and collecting hydrogen coming out through the membrane. By recovering, high-purity hydrogen can be recovered from the hydrogen mixed gas or used as a process for purifying hydrogen. The Pd film as the hydrogen permeable film is to reduce the product cost as much as possible because Pd is an expensive metal, to improve the hydrogen permeation performance more than the current level, to prevent the deterioration of hydrogen permeability during use, It is expected that the application will be further expanded by achieving the prevention of embrittlement of the metal film material due to the above.

[0003] A conventional method of manufacturing a Pd metal film is outlined as follows. A material metal such as Pd or a Pd-Ag (palladium / silver) alloy is annealed and cold rolled. Note that Pd causes irreversible deformation (shrinks in length and width and increases in thickness) by repeating the phase change between the α phase having a low hydrogen concentration and the β phase having a high hydrogen concentration. Alloys with A thin film of Pd or a Pd alloy is formed on the surface of a porous body serving as a support of the Pd film by plating or vapor deposition operation (for example, electroplating, electroless plating, vacuum vapor deposition by electron beam heating, etc. are applied). . The above-described method is basically used for manufacturing a metal film, and various techniques have been incorporated into the method for reducing the thickness of the film, preventing defects of the film, and improving the strength. In addition, efforts have been made to improve the film performance by making efforts to improve the metal film material, and a method of blending various rare earth elements (yttrium, cerium, lanthanide, etc.) with Pd or Pd-Ag alloy (Japanese Patent Publication No. 52-1982). 28748) has also been proposed.

FIG. 2 shows an example of the structure of a conventional hydrogen separation membrane.
I will explain using. A metallic hydrogen-permeable metal foil 4 manufactured by cold rolling is placed on a reinforcing plate 5 having a large number of holes in order to reinforce the strength of the hydrogen separation membrane. The reinforcing plate 5
In order to maintain the strength, the number of sheets is often plural. In this example, three reinforcing plates 5 are provided. Furthermore, hydrogen permeable membrane 4
In order to collect hydrogen passing through the reinforcing plate 5 through the base plate 6, the base member 6 having a plurality of grooves is superimposed thereon, and then the periphery of each member 4, 5 and 6 is integrated by seal welding. As a hydrogen separation membrane module. in this case,
When the reinforcing plate 5 supports the strain resulting from the pressure difference during operation,
The film thickness is restricted by the pore diameter of the perforated plate, and a plate having a thickness of 15 μm or less cannot be used conventionally. In addition, when producing a vapor-deposited film supported by a porous body, it is common to directly plate or vapor-deposit on a porous support having an average pore diameter of about 5 μm. A film thickness of at least 20 μm was required.

[0005]

By the way, in order to improve the performance of the hydrogen permeable membrane, the hydrogen permeation performance of the membrane itself is improved, and the thickness of the membrane is made as small as possible to reduce the hydrogen permeation resistance. (However, if the film thickness becomes smaller at this time, the film strength decreases), and to increase the hydrogen permeation amount, to realize a film having a large mechanical strength capable of increasing the pressure difference applied to both surfaces of the film, Ensuring the high temperature resistance required to ensure hydrogen permeation performance, ensuring that the metal of the membrane does not undergo metallurgical changes due to contact with hydrogen, and that the service life of the membrane can be maintained long;
Etc. are required. The present invention seeks to improve the hydrogen permeable performance, hydrogen embrittlement resistance and high temperature resistance of a hydrogen permeable alloy film.

[0006]

Means for Solving the Problems Making the thickness of a hydrogen permeable membrane made of a metal such as Pd as small as possible contributes to the improvement of the performance of a high-purity hydrogen separation membrane. A columnar structure serving as an intermediate support having pores having a pore diameter of 0.1 μm or less is formed thereon by vapor deposition to prepare a surface state, and a hydrogen-permeable metal film layer of Pd or a Pd alloy is formed thereon. As a result, the generation of film defects in the hydrogen permeable film was suppressed, and a practically practicable hydrogen permeable film could be formed with a minimum thickness. In addition, the said metal porous body was put in order to have the practical strength as a hydrogen separation membrane,
A high-strength porous material made of nonwoven fabric or the like is preferable. If a metal such as Co or Ni or a ceramic such as ZrO ₂ is used as the material of the columnar structure (film), a good quality film can be formed. Furthermore, when the hydrogen permeable membrane is made of pure Pd, an alloy of Pd and Ag, or an alloy of one or more metals selected from the group consisting of rare earth elements such as Pd and Y, high quality hydrogen selective permeability is obtained. Can be obtained. Note that Pd is a basic composition, and Y, Gd, L
In an alloy film containing a rare earth element of u, Y, Gd,
It was confirmed that by limiting the Lu content to a certain range, a highly practical hydrogen separation membrane having high hydrogen permeation performance, low hydrogen embrittlement resistance, and high high-temperature strength can be manufactured.

[0007]

[Function] In order to maintain the practicality of a hydrogen-permeable film having a small film thickness, there is no defect (breakage, etc.) in the film even if the film thickness is small.
Even a thin film needs to withstand the stress generated during handling or use of the film and not be damaged. For this reason, by forming a hydrogen-permeable film on the surface of a smooth support having no defects based on the present invention, it is possible to prevent the occurrence of defects in the film, and furthermore, there is a problem in film formation. Since the number is reduced, the film thickness can be made smaller than before. Further, since the columnar structure film having a high surface smoothness is deposited and formed on a porous material having a higher strength such as a metal nonwoven fabric, the overall strength of the hydrogen separation film can be significantly increased. Furthermore, since the ventilation resistance of the columnar structure membrane and the porous metal body is small,
Even if a composite membrane is made as a hydrogen separation membrane, the total pressure loss of the generated hydrogen separation membrane can be kept small.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Note that the present invention is not limited to these examples. (Example 1) First, a metal porous body 1 constituting a hydrogen separation membrane 1
A test was conducted to select As the metal porous body 1, a metal nonwoven fabric (pore diameter 5 to 10 μm) having the smallest pore diameter of the porous body among available ones was used. The columnar structure film 2 formed thereon was formed using an electron gun heating type vacuum evaporation apparatus. Incidentally, when the pressure loss is small (acceptable pressure loss H ₂ is transmitted through the film at a rate of ^{20m 3 N / m 2 h,} 0.1a
In order to form the columnar structure film 2, the degree of vacuum is 5 × 10 ⁻⁵ Torr or more, and the film formation rate is 2 μm / min.
Since the film thickness was 10 μm / min and the film thickness was 300 μm, it was found that the film should be formed under the condition of a film thickness of 40 μm or more, which hardly causes a film formation defect. Regarding the species of the material, no change was observed between the tested Ni, Co, ZrO ₂ + 8% Y ₂ O ₃ , and the difference between Ar and O ₂ used for the introduced gas was not clear. The columnar structure film 2 formed within these condition ranges has a columnar structure of about 0.1 μm, and the gap between the columnar structures serves as a vent. Therefore, the pore diameter of the vent hole is 0.1 μm or less and linear. On the metal non-woven fabric, Ni was used for the columnar structure material, Ar was used as the introduced gas, and the degree of vacuum was set to 5 × 10 ⁻⁴ Torr using the above-described vapor deposition apparatus.
r, a film forming speed of 10 μm / min, and a film thickness of 40 μm
Was formed, and Pd was vacuum-deposited thereon to a thickness of 5 μm. As a result of measuring the performance of the hydrogen separation membrane thus produced, the permeability was 500 ° C., 2 kgf / cm ^2.
Under the operating conditions described above, the hydrogen permeation performance was 45.6 m ³ N / m ² h, and it was confirmed that this was a highly practical hydrogen separation membrane.

(Embodiment 2) The columnar structure material was Ni, the introduced gas was Ar, the degree of vacuum was 5 × 10 ⁻³ Torr, and the film formation rate was 10 μm / min. A 200 μm thick columnar structure 2 was formed on the metal nonwoven fabric. Further thereon, Pd was vacuum-deposited to a thickness of 5 μm to produce a hydrogen separation membrane as a trial. The hydrogen permeation performance of the prototype was measured by the same test method as in Example 1, and as a result, the hydrogen permeation performance was 40.5 m ³ N / m ² h, indicating sufficient performance as a practical membrane. (Example 3) The same test as in Example 2 was performed. However,
The material of the hydrogen permeable membrane is Pd-23% Ag alloy, and the film thickness is 1
μm. The performance of the hydrogen separation membrane was measured using the same measurement method as in the above example. As a result, the hydrogen permeation amount was 118 m ³ N
/ M ² h, indicating that the membrane is a high-performance hydrogen separation membrane.

Example 4 The same test as in Example 2 was continued. However, the material of the hydrogen permeable membrane is Pd-8%
Y, the film thickness is 1 μm. The performance of the hydrogen separation membrane was measured using the same measurement method as in the above example. As a result, the hydrogen permeability was 144 m ³ N / m ² h, and a high performance hydrogen separation membrane was obtained. (Example 5) The same columnar structure as in Example 2 was used as a base,
A hydrogen permeable film was formed by a plating method. In this embodiment, P
The plating thickness was controlled to 2 μm by applying an electroplating method using an ammoniacal plating solution in which d was dissolved. The performance of the hydrogen separation membrane was evaluated by the same measurement method as in the previous example, and the hydrogen permeation performance was 80.3 m ³ N / m ² h.
And showed extremely high performance. Example 6 The same test as in Example 5 was performed except that the material of the hydrogen-permeable film was Pd + 23% Ag and the film thickness was 1 μm. The hydrogen permeation performance of the hydrogen separation membrane is 136 m ³ N /
m ² h, indicating that the Pd + 23% Ag material gave good results.

[0011]

According to the present invention, the following effects can be obtained. The surface roughness is small, the smoothness is high, the surface condition is uniform, and the hydrogen permeable film is coated and formed on the basis of the highly reliable columnar structure film as the bonding surface of the hydrogen permeable film, An extremely thin and defect-free high-performance hydrogen permeable membrane can be produced. Since the columnar structure membrane is formed on a porous substrate having high strength, such as a metal nonwoven fabric, and formed on the substrate, the hydrogen separation membrane can have practically high strength. Since the permeability of the columnar structure membrane and the porous metal body is sufficiently large, in combination with the small thickness of the hydrogen permeable membrane,
The pressure loss during operation can be made smaller than that of a conventional hydrogen separation membrane. Compared to other methods of assembling a composite membrane in which a hydrogen permeable membrane is formed on a polystyrene film and the like, and then a columnar porous membrane is formed thereon as a porous body, the method of the present invention is a slightly hydrogen permeable membrane. Although the thickness is increased, the handling of membrane fabrication is easier and the fabrication costs can be lower.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a hydrogen separation membrane according to one embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a conventional hydrogen separation membrane.

[Explanation of symbols]

 Reference Signs List 1 porous metal body 2 columnar structure film 3 hydrogen permeable film

Claims (3)

[Claims] 1. A surface of a metal porous support such as a metal nonwoven fabric is coated with a columnar structure film by a vacuum deposition method at a thickness of 40 to 300 μm, and a film such as Pd that selectively transmits only hydrogen is coated at a thickness of 1 to 20 μm. A hydrogen separation membrane, comprising: 2. The membrane selectively permeating only the hydrogen,
The hydrogen separation membrane according to claim 1, wherein the hydrogen separation membrane is pure Pd, an alloy composed of Pd and Ag, or an alloy composed of one or more metals selected from the group consisting of Pd, Y, and a rare earth element. As 3. A columnar structure film, the material is Co, the metal or ceramics such as ZrO ₂ such as Ni, 2 × 10 ^-3 Torr vacuum degree 5 × 10 ^-4 Torr by a vacuum deposition method,
A method for producing a hydrogen separation membrane, characterized in that it is produced under conditions of a film formation rate of 2 μm / min or more.