JPH11104472A - Permeable membrane structural body for hydrogen refining, its manufacture and hydrogen refining apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permeable membrane structural body of a palladium alloy having a good permeating efficiency. SOLUTION: A permeable membrane structural body 10 comprises a palladium alloy membrane 1 and a grid-like support flame 2 mechanically supporting the membrane. The membrane structural body 10 is prepared by the steps of subjecting an electrically conductive substrate to electrolytic plating so as to form a layer comprising palladium and silver which constitutes a permeable membrane, forming a desired photoresist pattern on a surface thereof by X rays or photolithography, forming a metal layer which functions as the support frame by electrolytic plating, removing the photoresist pattern and separating the electrically conductive substrate from a pemeable membrane layer. Thus, because strength of the support flame can be enhanced, area occupied by a grid window can be increased and thickness of the palladium alloy membrane 1 can be reduced so that hydrogen refining efficiency is raised. By using this permeable membrane structural body, a hydrogen refining apparatus reduced in size and having a high performance can be produced at low costs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrogen purifier using a palladium permeable membrane, and more particularly to a structure of a palladium permeable membrane.

[0002]

2. Description of the Related Art High-purity hydrogen gas is used as a reducing gas in the semiconductor industry in large quantities as a component gas. Hydrogen gas is an environmentally friendly clean energy source, and great demand is expected as a raw material gas for electric vehicles and storage batteries. For this reason, it is desired to provide a device that can supply high-purity hydrogen gas at low cost. Among these, it is epoch-making that a hydrogen purifier capable of extracting high-purity hydrogen gas can be reduced in cost by utilizing the property of a metal palladium membrane that allows only hydrogen to pass efficiently. At present, a commercially available apparatus hermetically seals a thin tube 100 covered with a palladium alloy film as shown in FIG. 10, heats this at a temperature of about 500 ° C., and pressurizes a raw material gas 107 outside the thin tube. The configuration is such that only hydrogen is permeated into the inside of the thin tube to obtain high-purity hydrogen gas 108. The impurity gas that cannot be permeated inward by permeation is discharged outside as a bleed gas 109 together with the hydrogen gas. A conventional palladium alloy thin tube used in a hydrogen purifier has a structure in which a cylinder is formed from a sintered body of powder, and a palladium alloy film is deposited on the cylinder by sputtering or vapor deposition. About 10 atm of raw material hydrogen is added to the palladium alloy film, and it is necessary that the palladium alloy film has no pinhole over the entire surface of the thin tube. For this reason, the palladium alloy film thickness of the conventional structure is about 60
μm had been deposited.

[0003]

The conventional structure of the palladium alloy thin tube has the above-mentioned structure, so that the film forming process is complicated and unsuitable for mass production, and therefore has a disadvantage of high cost. Further, a cylinder formed of a sintered body has a drawback that the permeation efficiency of hydrogen varies depending on the particle diameter and density, and the quality varies. This is because when the particle size of the sintered body is large, the thickness of the palladium alloy is increased so as to eliminate pinholes,
On the other hand, when it is small, the area through which hydrogen passes is small, and in any case, there is a disadvantage that the hydrogen transmission efficiency is reduced. Further, in order to heat the conventional palladium alloy structure to a high temperature of about 500 ° C., the conventional hydrogen purifier has a large configuration. In addition, conventional hydrogen purifiers tend to cause pinholes in the permeable membrane structure during use, which is likely to be due to the use of a sintered body.However, repairs should be replaced with new tubes of new palladium alloy. Defective products were discarded, so repair costs were high.

[0004] A first object of the present invention is to provide a permeable membrane structure made of a palladium alloy at a low cost, which has been made in order to solve the conventional disadvantages and has a high permeation efficiency. Also,
A second object of the present invention is to provide a method for manufacturing the permeable membrane structure at low cost. Further, a third object of the present invention is to provide a hydrogen purifier that is smaller than the conventional one by using the above permeable membrane structure at low cost.

[0005]

Means for solving the problems of the prior art are described below. FIG. 1 shows a portion of a permeable membrane structure which is the basis of the present invention. This permeable membrane structure is composed of a palladium alloy membrane 1 as a permeable membrane and a lattice-shaped support frame 2. The support frame 2 is mechanically a palladium alloy film 1
And the hydrogen is purified by the palladium alloy film 1 in the window 3 of the lattice. Therefore, the larger the area occupied by the window portion 3 than the support frame 2, the better the hydrogen purification efficiency, and the thinner the film thickness of the palladium alloy film 1, the higher the hydrogen permeation efficiency. This permeable membrane structure is mainly formed in a thin-film sheet shape, and the shape incorporated in the hydrogen purification device is a flat plate or a cylindrical structure. When the lattice pitch is the same, the lattice window over which the palladium alloy film 1 is stretched to increase the transmission efficiency,
It is better to make the width of the grid frame narrower, but in order to make this permeable membrane structure mechanically strong, it is necessary to make the grid as the support frame 2 sufficiently thick. This lattice structure can be easily formed in a large area by the technique of light or X-ray lithography and electrolytic plating. Further, this manufacturing method has a feature that the cost can be easily reduced because of good reproducibility. Further, the palladium alloy film 1 is formed by electrolytic plating similarly to the support frame 2, so that the film quality is good. As a result, there is no pinhole even with a small film thickness. The thickness of the palladium alloy film 1 is determined in relation to the lattice structure so as to sufficiently withstand the working pressure, but is usually about 20 μm.
Since this can be made much thinner than the conventional structure having a thickness of about 60 μm, the hydrogen permeation efficiency is remarkably improved. As described above, the first object of the present invention is achieved by a permeable membrane structure including a palladium alloy membrane as a permeable membrane and a lattice-shaped support frame. The second object of the present invention is achieved by a manufacturing method using optical or X-ray lithography and electrolytic plating.
The third object of the present invention is achieved by using the permeable membrane structure of the present invention having high transmission efficiency.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG.

Embodiment 1 First, a first embodiment will be described in detail with reference to FIG. This is a perspective view of a portion of a permeable membrane structure showing one embodiment of the present invention. The permeable membrane structure is composed of a palladium alloy membrane 1 which is a permeable membrane and a lattice-shaped support frame 2. Support frame 2
Is an alloy such as Ni or NiPd formed by electrolytic plating. The permeable film is a palladium alloy film 1 obtained by alloying the structure of a Pd layer and an Ag layer formed by electrolytic plating with heat treatment, similarly to the support frame 2. The dimensions are, for example, a lattice thickness: 60 μm, a lattice frame width: 20 μm, a lattice window: 100 μm, and a palladium alloy film thickness: 5 μm. In this case, the effective area of the window for hydrogen permeation is 69%, which is sufficiently larger than the conventional sintered body. When a pattern is formed by X-ray lithography, a grid width: 5 μm and a grid window: 115 μm can be formed with good reproducibility with respect to the same grid thickness, so that the effective area of the hydrogen-permeable window is 92%.
To improve. The window shape of the support frame is not limited to a square or a rectangle. Since the permeable membrane structure of the present invention is formed by lithography and electrolytic plating, a large-area plate-shaped product can be easily obtained. For this reason, since it can be manufactured in large quantities, there is a feature that the cost can be greatly reduced. Further, as in the present invention, the lattice-shaped permeable membrane structure can repair a failure of a pinhole due to a foreign substance or the like. This is because the support frame looks for pinholes because of the lattice structure,
This is because this portion can be easily repaired by covering it with metal such as plating. With this system, all of the permeable membrane structures according to the present invention can be recycled, and the cost can be significantly reduced.

Embodiment 2 Next, a second embodiment will be described in detail with reference to FIG. This is another structure of the permeable membrane structure described in the first embodiment. The permeable membrane structure is a palladium alloy membrane 21 which is a permeable membrane.
And a metal net-shaped support frame 22. The support frame 22 is a mesh (mesh) made of a normally available stainless steel thin wire or Ni thin wire. The permeable film is a palladium alloy film 21 obtained by alloying a Pd layer and an Ag layer formed by electrolytic plating with heat treatment. The dimensions are, for example, mesh pitch: about 100 μm, fine wire diameter: 5
The thickness of the palladium alloy is 30 μm with respect to 0 μm.
The hydrogen gas is purified by the palladium alloy film through the gap of the mesh. In this embodiment, the lithography technique is not required, and the structure is such that the permeable membrane structure is formed by electrolytic plating on the support frame of a commercially available mesh, so that the cost can be greatly reduced.

Although the examples of the permeable membrane structure of the present invention have been described in the first and second embodiments, the gist of the present invention is based on a configuration using a support frame for the permeable membrane structure. The structure and the manufacturing method of the support frame described above are not limited. For example, a palladium alloy film and the support frame may be bonded or pressed to form this structure.

Embodiment 3 Next, a third embodiment will be described in detail with reference to FIG. This is one embodiment of the method for manufacturing the permeable membrane structure described in the first embodiment. For example, a conductive substrate 35 such as a stainless steel plate
Then, a permeable film (which becomes a palladium alloy film after heat treatment) 31 having a structure of Pd-Ag is formed to a thickness of 5 μm by electrolytic plating (a). Next, a desired photoresist pattern 33 is formed on this surface by photolithography. This film thickness is 60 μm, and the space width of the pattern shape is 20 μm.
m, pitch is 120 μm (b). Subsequently, a nickel grid support frame 32 is formed to the same thickness (60 μm) as the photoresist pattern 33 by electrolytic plating (c). Thereafter, the photoresist pattern 33 is removed to obtain the support frame 32 (d). Further, the conductive substrate 35 is connected to the permeable film 31.
Then, a permeable membrane structure including the permeable membrane 31 and the support frame 32 is manufactured (e). This permeable membrane structure can be easily formed into a sheet having a width of 60 cm, although it depends on the manufacturing equipment. When X-ray lithography is used instead of the photoresist pattern, the space pattern can be processed and formed with a height / width ratio of about 15, and has a feature that a structure of a grid frame having a strong strength and a grid window having a large effective area can be formed. .

Embodiment 4 Next, a fourth embodiment will be described in detail with reference to FIG. This is one embodiment of the method for manufacturing the permeable membrane structure described in the second embodiment. A mesh (mesh) 42 of a stainless steel plate is closely attached to a stainless steel plate 45 as a conductive substrate (a), and the whole is electrolytically plated to form a copper film 43 having a thickness of about 50 μm (b). Copper is an example of a metal layer that is easily dissolved in a chemical solution. After the copper plating material 43 is removed from the stainless steel plate 45, a permeable film 41 (which becomes a palladium alloy film after heat treatment) 41 made of Pd-Ag by electrolytic plating is placed on the flat surface.
It is formed to a thickness of μm (c). Thereafter, only the plated copper is removed by chemical etching to form a permeable membrane structure (d). As a result, a structure in which a part of the stainless steel plate mesh (mesh) 42 as a support frame and the permeable membrane 41 have sufficient mechanical strength is obtained.

Although the examples of the method for manufacturing the permeable membrane structure according to the present invention have been described in Examples 3 and 4, the gist of the present invention is that the manufacturing method is based on the basic structure of the permeable membrane structure as a permeable membrane and a support frame. Therefore, the present invention is not limited to the manufacturing method described in the embodiment.

Embodiment 5 Next, a fifth embodiment will be described in detail with reference to FIG. This is an example of the configuration of the hydrogen purifier using the permeable membrane structure described in the first embodiment. Palladium alloy film 51
And the cylindrical permeable membrane structure 50 composed of the lattice-shaped support frame 52 is hermetically sealed in a stainless steel container 55 using a reinforcing component 53 and metal seals 54 and 54 '. The cylindrical structure is formed by processing a sheet-shaped permeable membrane structure into a cylindrical shape, and joining only this joint portion with a plating metal by electrolytic plating to maintain a seamless and airtight structure. This is heated by a heat source 56 at a temperature of about 500 ° C., and a pressurized raw material gas 57 is introduced from the outside of the cylindrical permeable membrane structure 50, and only hydrogen is permeated into the inside thereof to form a high-purity hydrogen gas 58. Is obtained. The impurity gas that cannot be permeated inward by permeation is discharged outside as a bleed gas 59 together with the hydrogen gas. The permeable membrane structure used for this may have the structure of FIG.

Embodiment 6 Next, a sixth embodiment will be described in detail with reference to FIG. This is another embodiment of the hydrogen purifier described in the fifth embodiment.
The permeable membrane structure 60 composed of the palladium alloy film 61 and the lattice-shaped support frame 62 has a feature that, despite its thin film thickness, it is durable and easy to handle because of the lattice structure, so that it can be easily processed into a small-diameter cylindrical shape. A configuration utilizing this advantage is an embodiment of the present invention. Seamless capillary tube permeable membrane structure 60
Are arranged in large numbers to increase the hydrogen gas permeation area. This allows a device of the same capacity to be miniaturized. In addition, since the permeable membrane structure 60 is densely packed in the stainless steel container 65, the efficiency of heating the structure with the heat source 66 is superior to the conventional one. The pressurized raw material gas 67 is introduced from the outside of the cylinder, and high-purity hydrogen gas 6
The configuration for obtaining 8 from the inside is the same as above, but may be reversed. The permeable membrane structure used for this may have the structure of FIG.

Embodiment 7 Next, a seventh embodiment will be described in detail with reference to FIG. This is another embodiment different from the hydrogen purifier described in the fifth and sixth embodiments. The permeable membrane structure 70 including the palladium alloy film 71 and the lattice-shaped support frame 72 is characterized in that it is basically used in a sheet shape. Even though the permeable membrane structure 70 is thin, it is durable and easy to handle because of the lattice structure. Therefore, two of them are combined in parallel to form the permeable membrane structure of the hydrogen purifier. A gap of several mm or less is sufficient for the parallel plate. When a sheet having a large area is used, an appropriate reinforcing structure is added so that the permeable membrane structure 70 withstands pressure. The feature of this hydrogen purification apparatus is that a permeable membrane structure having a large permeation area can be arranged in a small volume, so that an apparatus having the same purification capacity can be significantly reduced in size. The heating efficiency by the heat source 76 has been remarkably improved due to the miniaturization. The principle of supplying the pressurized source gas 77 from the outside of the plate and obtaining the high-purity hydrogen gas 78 from the inside of the plate is the same as that described above, and vice versa. The permeable membrane structure used for this may have the structure of FIG.

Embodiment 8 Next, an eighth embodiment will be described in detail with reference to FIGS. This is also characterized in that the permeable membrane structures 80c and 90c composed of a palladium alloy membrane and a lattice-shaped support frame are used in the form of a sheet, similarly to the hydrogen purifier described in the seventh embodiment.
FIG. 8 is an example of a structural diagram using the permeable membrane structure 80c as a unit cell. The permeable membrane structure 80c is hermetically sealed in the unit cell containers 85c and 85c ′ by metal seals 84c and 84c ′, and the left and right chambers in the cross section in the figure are completely isolated by the permeable membrane structure 80c as a partition. Structure. The left chamber of the cross section in the figure is the source gas 87c and the bleed gas 8
The right chamber is connected by a pipe of high-purity hydrogen gas 88c. Usually, since the gap is small in both the left and right chambers, the partition walls are resistant to pressurization, and may be strengthened by appropriately adding a reinforcing structure. This structure corresponds to a unit configuration of a hydrogen purifier, and a large number of hydrogen purifiers are used in parallel to form a large-capacity hydrogen purifier. This embodiment is shown in FIG. This is an example in which ten cells are used, and the raw material gas 97 is heated by the heat source 96 and the permeable membrane structure 90 c of each partition is heated.
And a large amount of high-purity hydrogen gas 98 is obtained as a whole. In this configuration, since the unit cell can be manufactured extremely small and lightweight, the hydrogen purifier can be significantly reduced in size and weight and can be manufactured at low cost. In addition, since each unit cell can be opened and closed by a valve, it is easy to deal with a pinhole failure, and since the device can be repaired for each unit cell, the cost of repair can be reduced. Further, the structure of the unit cell may be such that a heat source is attached to the surface of the unit cell and the unit is used as one unit. The permeable membrane structure used for this may have the structure of FIG.

As described above, in Examples 4 to 8, examples of the basic structure of the hydrogen purifier equipped with the permeable membrane structure of the present invention have been described.
The gist of the present invention is to provide a device for obtaining high-purity hydrogen gas using a permeable membrane structure having a support frame, and is not limited to the configuration described in the embodiment.

[0018]

【The invention's effect】

(1) By constructing the permeable membrane structure of the hydrogen purifier with a palladium alloy membrane and a support frame, the hydrogen purification efficiency could be greatly improved. (2) Since the permeable membrane structure of the present invention is formed by the technique of light or X-ray lithography and electrolytic plating, the production yield is high, large-area products can be mass-produced, and this part can be supplied at low cost. It became so. (3) The above-mentioned permeable membrane structure is mounted on a hydrogen purification device, and a high-performance, small-sized device can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of a permeable membrane structure according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of a permeable membrane structure according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of a part of a wrapping carrier according to a second embodiment of the present invention.

FIG. 4 is a side sectional view showing a main manufacturing step of the permeable membrane structure according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a hydrogen purification apparatus according to a fifth embodiment using the permeable membrane structure of the present invention.

FIG. 6 is another configuration diagram of the hydrogen purification apparatus of Embodiment 6 using the permeable membrane structure of the present invention.

FIG. 7 is another configuration diagram of the hydrogen purification apparatus of Embodiment 7 using the permeable membrane structure of the present invention.

FIG. 8 is a configuration diagram of a unit cell for a hydrogen purification apparatus according to Embodiment 8 using the permeable membrane structure of the present invention.

FIG. 9 is a configuration diagram of a hydrogen purification apparatus according to Embodiment 8 using the permeable membrane structure of the present invention.

FIG. 10 is a configuration diagram of a conventional hydrogen purification apparatus using a thin tube of a palladium alloy membrane.

[Explanation of symbols]

10, 20, 30, 40, 50, 60, 70, 80c,
90c, 100: permeable membrane structure 1, 21, 31, 41, 51, 61, 71: palladium alloy film 2, 22, 32, 42, 52, 62, 72 ... support frame 35, 45 ... conductive substrate 33 ... Photoresist pattern 43 Copper plating layer 53 Reinforcement parts 54, 54 ', 84c, 84c' Metal seal 55, 65, 75, 105 Container 85c, 85'c Unit cell container 56, 66, 76, 96, 106 ... Heat sources 57, 67, 77, 87c, 97, 107 ... Source gases 58, 68, 78, 88c, 98, 108 ... High-purity hydrogen gas 59, 69, 79, 89c, 99, 109 ... Bleed gas.

Claims (9)

[Claims] 1. A permeable membrane structure for hydrogen gas purification,
A permeable membrane structure having a structure in which a permeable membrane is fixed to a support frame and a window of the support frame is covered with the permeable membrane. 2. A permeable membrane structure for hydrogen gas purification,
The permeable membrane structure according to claim 1, wherein the shape of the support frame is a lattice. 3. A permeable membrane structure for hydrogen gas purification,
The permeable membrane structure according to claim 1, wherein at least the permeable membrane is formed by electrolytic plating. 4. A permeable membrane structure for hydrogen gas purification,
The permeable membrane structure according to claim 1, wherein the permeable membrane includes a palladium and silver layer formed by electrolytic plating. 5. A method for producing a permeable membrane structure for purifying hydrogen gas, comprising the steps of: forming a layer of palladium and silver as a permeable membrane by electroplating on a conductive substrate; and forming a desired surface on the surface by X-ray or photolithography. Forming a photoresist pattern, forming a metal layer serving as a support frame by electrolytic plating, removing the photoresist pattern, and removing the conductive substrate from the permeable film layer. The method of manufacturing the structure. 6. A method for producing a permeable membrane structure for purifying hydrogen gas, comprising the steps of: adhering a metallic mesh to a conductive substrate; and applying a metal layer that is easily dissolved by a chemical solution to the surface by electrolytic plating. And a step of removing the conductive substrate from the plated metal mesh, a step of forming a layer of palladium and silver serving as a permeable film on the removed surface by electrolytic plating, and a step of removing a metal layer that is easily dissolved by a chemical solution. A method for manufacturing a permeable membrane structure based on the above. 7. A hydrogen gas purifying apparatus according to claim 1, wherein
5. A hydrogen gas purifying apparatus, wherein the apparatus is constituted by using any one of the permeable membrane structures according to 4. 8. A hydrogen gas purifying apparatus according to claim 1, wherein
5. A hydrogen gas purification apparatus, wherein a structure is formed by laminating two or more permeable membrane structures in a plane at intervals, and an apparatus is configured using the structure. 9. A hydrogen gas purifying apparatus according to claim 1, wherein
4. A unit cell of a hydrogen gas purification apparatus is formed by using any of the permeable membrane structures according to 4 as a sheet-shaped partition in a container of the unit cell, and using one or two or more unit cells in parallel A hydrogen gas refining device comprising a device.