JPH0686283B2 - Method for producing hydrogen separation medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a hydrogen separation medium used for recovery, purification, removal, etc. of hydrogen gas.

“Conventional technology and its problems” Conventionally, low-temperature adsorption method, Pd film method, etc. are known as methods for selectively recovering or separating high-purity hydrogen gas, and these methods are mainly adopted in the semiconductor industry. . However, since the low temperature adsorption method requires liquid nitrogen, it is subject to the regulations of the High Pressure Gas Control Law and cryogenic technology becomes indispensable.
Further, the Pd film method has the disadvantages that the film is expensive and the operating temperature is high. Therefore, the low temperature adsorption method and Pd
Both of the membrane methods have major problems in manufacturing and operating the device, and also have the drawback of high device cost.

In view of such a situation, a hydrogen separation method using an inexpensive hydrogen storage alloy has been proposed. However, in this method, the hydrogen-absorbing alloy is pulverized due to repeated storage and release of hydrogen, so there is the inconvenience that it is necessary to take measures against particles to prevent the hydrogen-absorbing alloy from being discharged outside the system. However, since it absorbs heat at the time of discharge, complicated thermal operations are required, and the container structure must withstand the stress associated with the volume expansion of the alloy.

Recently, as a solution to this problem, a hydrogen separation material has been proposed in which a hydrogen storage alloy is deposited on a substrate made of a porous body and the hydrogen storage alloy is formed into a thin film. However, the one in which the hydrogen storage alloy is directly deposited on the substrate has a drawback that the substrate and the alloy are separated due to the volume expansion of the alloy when hydrogen is stored. In order to solve this drawback, the substrate is subjected to a surface treatment by a method such as plating a transition metal or a metal of the group IIIb of the periodic table to increase the affinity with the alloy and to reduce the difference in the coefficient of thermal expansion. Attempts have been made to reduce the size. However, this method has a problem in that the film thickness of the metal deposited on the surface of the substrate becomes large, so that the hole diameter of the substrate is narrowed and the hydrogen permeation ability is lowered.
Further, particularly when the surface is plated, the production cost is increased due to the complicated process, and it is still difficult to remove the water remaining on the substrate.

The present invention has been made in view of the above problems, and an object thereof is to have an excellent hydrogen permeation ability, not to mix water into purified hydrogen, and to prevent peeling from a substrate. It is an object of the present invention to provide a manufacturing method capable of manufacturing a hydrogen separation medium including a hydrogen storage thin film having high bonding strength and having no pinhole in a simple process.

[Means for Solving the Problem] In order to solve the above-mentioned problems, the invention according to claim 1 comprises contacting a metal halide solution, a metal nitrate solution or a metal sulfate solution with a substrate made of a porous body. Cu, Zn,
Ni, Pd, Sn is formed by depositing metal nuclei of any one of the metal elements in a dispersed state, and then dried and baked at a temperature of 50 to 1200 ° C in a vacuum atmosphere or a reducing atmosphere. At the same time as removing water from the substrate, the metal nuclei are fixed, and then a hydrogen storage thin film having a thickness of 50 μm or less is formed on the substrate by a sputtering method.

In order to solve the above-mentioned problems, the invention according to claim 2 uses a Pd metal nucleus as a metal nucleus and LaNi as a hydrogen storage thin film.
The thin film of ₂ is used.

In order to solve the above-mentioned problems, the invention according to claim 3 brings a Pd halide solution into contact with a substrate made of a porous body to deposit and form Pd metal nuclei in a dispersed state, and then to form a vacuum atmosphere or a reducing atmosphere. At 150 ° C or higher, the substrate is dried and baked to remove water on the substrate, and at the same time, the metal nuclei of Pd are fixed. Then, the amorphous state of LaNi ₂ is sputtered on the substrate. Thickness of 50 μm
The following hydrogen storage thin film is formed.

Hereinafter, the method for producing the hydrogen separation medium of the present invention will be described in detail.

First, a substrate (base) made of a porous body is prepared. As the porous body, one made of a material having high heat resistance such as a SUS filter, a ceramics filter, or a porous glass is preferably used, and the average pore diameter thereof is preferably 1 μm or less, and particularly the pore diameter distribution is uniform. Things are desirable.

Next, a metal is attached to the surface of the substrate to disperse and form metal nuclei. Here, any one of Cu, Zn, Ni, Pd, and Sn is used as the metal for attaching to form a metal nucleus.

As a specific method for forming the metal nuclei, a method using a halide solution, a nitrate solution or a sulfate solution of the above metal is preferably adopted. As a method of using these metal salt solutions, for example, a method of appropriately adjusting the pH of the metal salt solution to be used, then immersing the substrate in this solution, followed by drying and baking is adopted. As a more active method, metal ions with electrochemically different potentials are exchanged as in the activation treatment commonly used when plating on a non-conductive inorganic material, which causes metal nuclei on the substrate. It is also possible to use a method of forming.

Note that when performing the metal nucleation treatment on the substrate, it is possible to further strengthen the affinity between the substrate and the hydrogen-storing metal described later by performing the treatment a plurality of times, and thus the hydrogen-storing metal is separated from the substrate. It is preferable because it can be suppressed. In this case, it goes without saying that the metal nuclei must be formed by treating the substrate to such an extent that it does not close the holes.

When the metal nuclei are formed by using the metal salt solution as described above, after the treatment, 50 to 50
It is preferable to perform the drying treatment and the baking treatment in the temperature range of 1200 ° C. from the viewpoint of removing the water content of the produced hydrogen separation medium.

Then, a hydrogen storage metal is deposited on the substrate to form a hydrogen storage thin film to obtain a hydrogen separation medium. Here, the hydrogen occluding metal is a metal or alloy that reversibly occludes or desorbs only hydrogen under a certain condition and further permeates. Typical examples of such metals are LaNi ₅ and TiMn.
There is a group of alloys such as _1.5, which is generally called a hydrogen storage alloy. Further, metals such as Pd, V and Nb also have a hydrogen storage property, and are used as the hydrogen storage metal of the present invention together with the above alloy.

When an alloy group such as LaNi ₅ , TiMn _1.5 or the like is used as the hydrogen storage metal, a physical method such as a sputtering method is more suitable because the alloy composition can be easily controlled.

When a hydrogen storage metal is deposited on a substrate by such a deposition method, metal nuclei are formed on the substrate,
The obtained hydrogen storage metal thin film is firmly bonded to the substrate by interposing the metal nuclei.

The thin film obtained by depositing by such a physical method may be in an amorphous state or a crystalline state, but the amorphous state is more preferable. This is because the amorphous alloy generally has less volume expansion of the lattice when hydrogen is absorbed and has no grain boundary, so that the amorphous alloy is less likely to be broken than the crystalline alloy. The thickness of the thin film is, for example, LaNi ₅ , TiMn
_When forming a film of a hydrogen storage alloy such as _1.5 , it is preferable that the thickness is 50 μm or less because the hydrogen permeation rate per unit area is improved.

To purify a raw material hydrogen gas containing impurities, for example, using the thus obtained hydrogen separation medium, the raw material hydrogen gas is passed through the hydrogen separation medium at an appropriate pressure. Then, hydrogen molecules in the raw material hydrogen gas are dissociated as hydrogen atoms on the surface of the thin film made of a hydrogen storage metal and preferentially diffused in the thin film to be separated from the raw material hydrogen gas. In this case, due to the difference between the pressure of the raw material hydrogen gas and the pressure of the pure hydrogen gas in the raw material hydrogen gas, hydrogen atoms are diffused in the hydrogen occluding metal.

Further, the operating temperature at this time is preferably in a temperature range of about 100 ° C to 500 ° C, and when operating at a temperature of 500 ° C or higher, the pores of the substrate made of a porous body become small due to the thermal expansion of the substrate and the ventilation resistance is reduced. In addition, the heating cost rises and the operating cost of the apparatus rises. The pressure at which the raw hydrogen gas is passed through the hydrogen separation medium is mainly determined by the bending strength of the substrate at the operating temperature, but it is desirable to operate within the pressure range of the high pressure gas control method.

When purifying the raw material hydrogen gas in this manner, the purity of the raw material hydrogen gas used is preferably a small amount of oxidizing gas considering the surface oxidation of the hydrogen separation metal thin film in the hydrogen separation medium. It is advantageous in terms of durability of the hydrogen separation medium to use the raw material hydrogen gas whose total content is 0.1% or less.

[Operation] According to the method of claim 1, a metal halide solution, a metal nitrate solution, or a metal sulfate solution is brought into contact with a substrate made of a porous material to obtain a Cu, Zn, Ni, Pd, Sn solution. Metal nuclei of one of the metal elements selected from
Drying and baking are performed at a temperature of ~ 1200 ° C to remove water on the substrate and at the same time fix the metal nuclei, and then form a hydrogen-absorbing thin film having a thickness of 50 µm or less on the substrate by sputtering. Therefore, the metal nuclei can be firmly fixed on the substrate by the drying treatment and the baking treatment.
Unnecessary water and solvent around the metal nuclei on the substrate can be removed, and the hydrogen-storing thin film is formed thereon by the sputtering method. It firmly adheres to the base body through. Therefore, the hydrogen storage thin film does not peel off from the substrate. Further, as described above, since the hydrogen-storing thin film is formed on the substrate through the metal nuclei under good conditions, a good quality hydrogen-storing thin film without pinholes is produced. In addition, since it is possible to prevent water and solvent from remaining in the obtained hydrogen-absorbing thin film, it is possible to prevent water from being mixed into hydrogen when hydrogen is purified, and the dew point is low and the water content is sufficient. It is possible to obtain the removed high-quality hydrogen gas.

According to the invention of claim 2, since the Pd metal nuclei are used as the metal nuclei and the LaNi ₂ thin film is used as the hydrogen storage thin film, it is possible to surely obtain a good quality hydrogen storage thin film without pinholes. .

According to the invention of claim 3, in addition to obtaining the effects obtained by the inventions of claims 1 and 2, unnecessary water and solvent on the substrate can be completely removed, and a higher quality can be obtained. A high hydrogen storage thin film can be obtained. Furthermore, by making the hydrogen storage thin film amorphous, it is possible to reduce the deposition expansion during hydrogen storage, and it is possible to obtain a hydrogen storage thin film that is hard to crack and peels off because there are no grain boundaries.

[Examples] Hereinafter, the production method of the present invention will be described more specifically with reference to Examples.

First, it has a shirasu composition as a substrate and a thickness of 50 mm x 50 mm.
A 0.5 mm square plate-shaped porous glass was prepared. In addition,
The average pore diameter of this porous glass was 3000Å.

Next, wash the prepared porous glass substrate with acetone,
After that, the surface treatment was performed by the following operation procedure (1) to (5) to disperse and form metal nuclei on the substrate surface.

(1) Put the substrate in a processing container, and put MA in the container.
C-100 (Okuno Pharmaceutical Co., Ltd .; HCl + SnCl ₂ aqueous solution) was added to 50 ml of water at a ratio of 5 ml to prepare a treatment liquid,
The surface treatment is performed by stirring the treatment liquid at room temperature for 1 to 2 minutes.

(2) Remove the substrate from the processing container and wash it with a large amount of water.

(3) The substrate after cleaning is put in another processing container again, and MAC-200 (manufactured by Okuno Chemical Industries Co., Ltd .; HCl + PdC) is placed in this processing container again.
( ₂ ) Aqueous solution is added to 50 ml of water at a ratio of 5 ml to prepare a treatment liquid, and the treatment liquid is stirred at room temperature for 1 to 2 minutes to perform surface treatment.

(4) Remove the substrate from the processing container and wash it with a large amount of water.

(5) The steps (1) to (4) are repeated 5 times, and then vacuum-dried at a temperature of 150 ° C. for 30 minutes, whereby Pd metal nuclei are formed on the substrate surface.

Then, using a high-frequency magnetron sputtering method, LaNi ₂ was deposited on the surface of the substrate under the following conditions to form a thin film to obtain a hydrogen separation medium.

Here, a split target was used as the sputtering target. The split angle of this split target is L
It was a: 40 ° and Ni: 50 °, and four each were prepared and laminated in a disk shape to obtain a target. The sputtering conditions were as follows.

(I) Atmosphere 4 × 10 ^-3 Torr (Ar) (ii) Substrate drying 150 ° C, 300sec, (iii) Etching 150 ° C, 200W, 30sec, (iv) Pre-sputtering 200W, 180sec, (v) Sputtering 100 ° C, The thin film obtained by sputtering at 800 W for 1800 sec under the above conditions had a thickness of 5 μm and had a composition of LaNi ₂ .

Immediately after film formation, the hydrogen separation medium thus obtained was pressurized with hydrogen at 130 ° C. and 15 atm, and the state after hydrogen storage was subjected to X-ray diffraction. As a result, a hydrogen storage alloy thin film composed of LaNi ₂ was found to be amorphous. It was confirmed that it was in a state.

Furthermore, after hydrogen-pressurizing this hydrogen separation medium at 300 ° C. and 15 atm, the state was observed using a scanning electron microscope. No pinholes were observed in the thin film, and the hydrogen storage alloy (LaNi ₂ No peeling from the substrate was observed, and a good condition was maintained.

Next, the hydrogen separation medium thus obtained was loaded into the hydrogen separation apparatus shown in FIG. 1 and the amount of He leak was measured.
In FIG. 1, reference numeral 1 is a hydrogen separation device, and 2 is a hydrogen separation medium obtained in the above embodiment.

Explaining the operation method of the measurement, first, the hydrogen separation medium 2 is set in the processing chamber in the hydrogen separation apparatus 1 as shown in FIG. Here, the hydrogen separator 1 includes an outer wall 3 made of a heat insulating material.
A processing chamber 4 is formed inside, and a heater 5 connected to a temperature controller to be described later is arranged between the outer wall 3 and the processing chamber 4, and a gas supply pipe 6 and a gas exhaust are provided in the front-back direction of the processing chamber 4, respectively. The pipe 7 is connected to the outside of the outer wall. When setting the hydrogen separation medium 2,
The thin film side made of a hydrogen-absorbing metal is the gas supply pipe 6 side,
The front and rear of the separation medium 2 are fixed by two O-rings 8, 8 so that the space before and after the separation medium 2 in the processing chamber 4 is separated.
Airtightly shut off by.

Next, the processing chamber 4 is covered with a lid (not shown) to make the inside of the processing chamber 4 airtight, and then a certain amount of He gas is supplied from the gas supply pipe 6 into the processing chamber 4 to remove the He gas from the gas discharge pipe 7. The emission amount was measured and the He leak amount was examined. At the time of measurement, the temperature sensor 10 connected to the temperature controller 9 is previously inserted and arranged in the gas supply pipe 6, and the heater 5 is controlled by the temperature controller 10 from the gas temperature detected by the temperature sensor 9 to supply gas. Temperature was kept constant. Further, the flow rate of the supply gas supplied into the processing chamber 4 was made constant by allowing a part of the supply gas to escape to the bypass pipe 11 connected to the gas supply pipe 6.

When the leak amount of He gas was examined in this manner, the leak amount was 2.0 × 10 ⁻⁹ atm · cc / sec or less, and it was confirmed that the produced thin film had no pinhole.

Then, using the hydrogen separation device shown in FIG. 1, the above hydrogen separation medium was set in the hydrogen separation device, and a mixed raw material hydrogen gas of Ar: 30 vol% and H ₂ : 70 vol% was aerated at 300 ° C. and 10 atm for hydrogen separation. Noh test was conducted. As a result, mixed raw material hydrogen gas is 99.99vol
It was confirmed that the hydrogen separation medium obtained according to the present invention, which had been purified to hydrogen with a purity of%, had a high hydrogen gas separation ability.

In addition, the hydrogen separation medium obtained by the method described above (sample of the present invention) and Cu on the porous glass substrate used in this example.
Electroless plating was performed, and the drying treatment of (5) described above was performed, and a sample in which a hydrogen-absorbing alloy film was produced under the same conditions as in the examples was used. Hydrogen was purified under the conditions, the dew point of the obtained purified hydrogen was measured, and the results are shown in Table 1.

From the results shown in Table 1, it was confirmed that the hydrogen purified by the sample of the present invention has a lower dew point than the raw material hydrogen gas having a purity of 99.99% and the water is almost completely removed. On the other hand, in the purified hydrogen obtained by the sample subjected to the electroless plating of Cu, the dew point is higher than that of the raw material hydrogen gas, and it is considered that the moisture is mixed in the purified hydrogen. It is suspected that it has occurred. The hydrogen permeation rate at this time was 0.56 cm in all cases.
^{It was 3} / cm ² · sec.

From the above results, it was found that the hydrogen separation medium obtained by the production method of the present invention has suppressed the peeling of the hydrogen storage alloy from the substrate because the water content is almost completely removed. It was confirmed that the hydrogen separation medium according to the present invention is sufficiently durable for use.

"Effects of the Invention" As described above, according to the method of claim 1, the metal halide solution, the metal nitrate solution, or the metal sulfate solution is brought into contact with the substrate made of a porous body to form Cu, Z.
Metal nuclei of any metal element selected from n, Ni, Pd, and Sn are deposited and formed in a dispersed state, and then dried and baked at a temperature of 50 to 1200 ° C in a vacuum atmosphere or a reducing atmosphere. The metal nuclei are fixed at the same time as the removal of water on the substrate, and then a hydrogen-absorbing thin film having a thickness of 50 μm or less is formed on the substrate by a sputtering method. The nucleus can be firmly fixed, and unnecessary moisture and solvent around the metal nucleus on the substrate can be removed. Furthermore, the hydrogen storage thin film is formed on the substrate by the sputtering method, so that the hydrogen storage thin film is unnecessary. Firmly adheres to the substrate through the metal core in the absence of water. Therefore, the hydrogen storage thin film does not peel off from the substrate.

Further, as described above, since the hydrogen-storing thin film is formed on the substrate through the metal nuclei under favorable conditions, it is possible to obtain a high-quality hydrogen-storing thin film having no pinhole and having high hydrogen separation ability. Since a uniform hydrogen-storing thin film without pinholes can be obtained, the thickness of the hydrogen-storing thin film can be made thinner than that of the conventional one. Therefore, when this hydrogen separation medium is used, the hydrogen permeation rate is high. Therefore, the hydrogen separation medium itself can be made compact.

Furthermore, after forming the metal nuclei, a drying process and a baking process are performed,
Since a hydrogen storage thin film is formed on it by the sputtering method,
It is possible to prevent water and a solvent from remaining in the obtained hydrogen-absorbing thin film, and prevent mixing of water in hydrogen when hydrogen is purified using the hydrogen separation medium obtained by the method of the present invention. It is possible to obtain hydrogen gas having a low dew point and sufficiently removed water.

Furthermore, since the hydrogen separation medium is manufactured by a simple process such as bringing the solution into contact with the substrate, further performing a drying process and a baking process, and performing sputtering, the manufacturing cost of the hydrogen separation medium can be reduced. .

According to the invention of claim 2, since the Pd metal nuclei are used as the metal nuclei and the LaNi ₂ thin film is used as the hydrogen storage thin film, it is possible to surely obtain a good quality hydrogen storage thin film without pinholes. .

According to the invention described in claim 3, in addition to obtaining the effects obtained by the inventions of claims 1 and 2, unnecessary water and solvent on the substrate can be completely removed, and water containing water can be contained. It is possible to obtain a higher quality hydrogen storage thin film. Furthermore, by making the hydrogen storage thin film amorphous, it is possible to reduce the deposition expansion during hydrogen storage, and it is possible to obtain a hydrogen storage thin film that is hard to crack and peel off because there are no grain boundaries.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a test method for investigating the hydrogen separation ability of the hydrogen separation medium obtained by the present invention, and is a schematic configuration diagram of the hydrogen separation device. 1 ... Hydrogen separation device, 2 ... Hydrogen separation medium.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Hasaka 4-320 Tsukagoshi, Sachi-ku, Kawasaki-shi, Kanagawa Examiner, Kazuko Yanagi (56) )

Claims (3)

[Claims] 1. A metal selected from Cu, Zn, Ni, Pd, and Sn by bringing a metal halide solution, a metal nitrate solution, or a metal sulfate solution into contact with a substrate made of a porous body. The metal nuclei of the element are deposited and formed in a dispersed state, and then dried and baked at a temperature of 50 to 1200 ° C in a vacuum atmosphere or a reducing atmosphere to remove water on the substrate and simultaneously fix the metal nuclei. Then, a method for producing a hydrogen separation medium, characterized in that a hydrogen storage thin film having a thickness of 50 μm or less is formed on the substrate by a sputtering method. _2. The method for producing a hydrogen separation medium according to claim 1, wherein a Pd metal nucleus is used as the metal nucleus, and a LaNi ₂ thin film is used as the hydrogen storage thin film. 3. A Pd halide solution is brought into contact with a substrate made of a porous body to deposit and form Pd metal nuclei in a dispersed state, and then dried at a temperature of 150 ° C. or higher in a vacuum atmosphere or a reducing atmosphere. And a baking treatment is performed to remove water on the substrate and at the same time to fix Pd metal nuclei, and then a hydrogen storage thin film of LaNi _{2 having} an amorphous state and a thickness of 50 μm or less is formed on the substrate by a sputtering method. A method for producing a hydrogen separation medium, which comprises: