JP2003190748A - Method for producing gas separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a simpler gas separator whereby a gas separator which has a higher gas separation efficiency and can give a purified gas with a specified purity can be produced. <P>SOLUTION: This method for producing a gas separator, by forming a metal film having a gas separation function on a porous substrate, comprises an activation step wherein at least one side of the porous substrate is dipped in a solution containing an activation metal without being accompanied by the pressure difference between the side and the other side and a chemical plating step wherein the one side of the porous substrate is dipped in a solution containing a metal having a gas separation function while being accompanied by the pressure difference between the side and the other side; thus, a metal having a gas separation function is formed into a film on the one side of the porous substrate while blocking minute defects on the surface of the porous substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a gas separator capable of obtaining a specific component gas by diffusively separating a multi-component mixed gas. More specifically,
The present invention relates to a method for producing a gas separator capable of obtaining a high-purity specific component gas with high gas separation efficiency by a simpler production means.

[0002]

2. Description of the Related Art Conventionally, a membrane separation method in which an organic or inorganic gas separation membrane is used for separation is known as a method for obtaining only a specific gas component from a multi-component mixed gas. The separation membrane used in the membrane separation method includes, for example, as the hydrogen separation membrane, an organic polymer membrane such as polyimide or polysulfone, and an inorganic compound membrane such as a palladium or palladium alloy membrane, or the like, and as an oxygen separation membrane. Is a silver or silver alloy film,
Etc.

In particular, it is known that the palladium or palladium alloy film also has heat resistance and that hydrogen of extremely high purity can be obtained. Palladium or a palladium alloy has a property of allowing hydrogen to pass through as a solid solution. Utilizing this property, a thin film made of palladium or a palladium alloy is widely used as a gas separator for separating hydrogen from a mixed gas containing hydrogen. Has been. However, this palladium thin film alone has a problem that the mechanical strength is weak.

Therefore, various proposals have been made to solve this problem. For example, JP-A-62-273
No. 030, the palladium or palladium alloy is adhered to the surface of an inorganic porous support such as porous glass, porous ceramics, or porous aluminum oxide to determine the mechanical strength of a thin film made of palladium or the palladium alloy. Suggestions have been made to raise it.

Further, in JP-A-3-146122, a palladium thin film is formed on the surface of a heat-resistant porous substrate by a chemical plating method, a silver thin film is formed on the palladium thin film by a chemical plating method, and then, A method for producing a hydrogen separator, which performs heat treatment, is disclosed. A hydrogen separator having a porous substrate and a palladium alloy thin film covering the porous substrate is obtained, and by heat treatment, palladium and silver are evenly distributed in the palladium alloy thin film.

Furthermore, US Pat. No. 3,359,705
No. 5,968,961 discloses a thin silver film that separates oxygen.

However, these gas separators
There is a problem that the raw material gas that undergoes gas separation leaks into the purified gas through minute defects penetrating a gas separation membrane made of a metal having gas separation ability (hereinafter also referred to as penetrating defects). There is. Therefore, the raw material gas is mixed into the purified gas, and the purity of hydrogen is greatly reduced.

For example, a method of producing a hydrogen separation membrane in which palladium is supported on an inorganic porous membrane disclosed in JP-A-63-171617 will be described in detail. In the publication, the inorganic porous membrane is palladium or palladium. The alloy is vapor-deposited by sputtering or the like, and then [Pd (N
It is disclosed that a H ₃ ) ₄ ] Cl ₂ aqueous solution is subjected to degassing under reduced pressure through an inorganic porous membrane and the solvent is evaporated to support palladium on the inorganic porous membrane. However, according to the example, this hydrogen separation membrane is not only permeable to hydrogen but also permeable to nitrogen, so that the small pores of the inorganic porous membrane are not blocked by palladium. Therefore,
Other component gases may be mixed in, leading to a decrease in the purity of hydrogen in the purified gas.

On the other hand, as a method for preventing the generation of such minute defects, a method of increasing the thickness of a gas separation membrane made of a metal having gas separation ability can be considered. However, this method may cause a problem that the gas permeability of the gas that permeates the gas separation membrane is lowered and the gas separation efficiency is lowered. That is, the desirable gas separation membrane is a gas separation membrane that has no penetration defects and can maintain the purity of the purified gas at a high level, and has excellent gas separation efficiency, but these conditions are contradictory and difficult to be compatible. It was

In order to solve the above-mentioned problems, the applicant has an activation step and a chemical plating step, and fills the small holes opened on the surface of the porous substrate with a metal having a gas separation ability. A method for producing a gas separator has been invented and disclosed (Japanese Patent No. 3213430). According to the invention, in the activation step, one surface of a porous substrate is immersed in a solution containing an activated metal so that the pressure applied to the one surface is larger than the pressure on the opposite surface of the porous substrate. As a result, the solution is allowed to enter the inside of the small holes opened on the surface of the one surface of the porous substrate, and the pressure applied to the one surface of the porous substrate is similarly applied in the chemical plating step. By immersing in a solution containing a metal having gas separation ability so that the pressure becomes higher than the pressure on one surface on the opposite side of the porous substrate, and by adhering the metal having gas separation ability to the small holes of the porous substrate, One embodiment is a method of filling a small hole with a metal having separability and closing the small hole.

According to this manufacturing method, the small holes of the porous substrate are sufficiently closed, the raw material gas does not leak into the purified gas, and the hydrogen gas having a purity of 99.99% or more is obtained. It is possible to obtain Further, the depth at which the metal having gas separation ability penetrates inside the small holes of the porous substrate is 3
If it is about 0 μm, a desired gas separation efficiency can be obtained. Therefore, the gas separator manufactured by this manufacturing method can solve the above-mentioned problems, and particularly the market that requires high-purity gas, such as semiconductor manufacturing process, high-purity hydrogen purification process, optical fiber manufacturing process, etc. Are welcomed into the market related to.

However, in recent years, the required specifications are changing depending on the market. For example, in the market for in-vehicle or domestic fuel cell systems, more emphasis is placed on the improvement of gas separation efficiency than the demand for improvement of the purity of the obtained purified gas, and there is a demand for cost reduction. It is increasing. The reason is, for example,
In addition to the aim of making equipment for gas separation compact, in addition to the recent sharp rise in the price of palladium, etc.

The gas separation efficiency referred to in the present invention means a gas permeation rate at which a gas permeates a gas separator, and refers to a gas permeation amount per time under a standard differential pressure. That is, a gas separator with high gas separation efficiency can reduce the equipment cost because it requires a smaller number of particles to purify and separate a predetermined amount of raw material gas under a constant supply pressure. Further, since the supply pressure required for purifying and separating a predetermined amount of the raw material gas with a fixed number of gas separators can be made smaller, the operating cost (electricity cost etc.) can be reduced.

Therefore, when the purity of the purified gas does not require very high purity, for example, the purity is 99 to 99.9%.
In the market that is small and can be dealt with, a production method capable of producing a gas separator having higher gas separation efficiency at a lower cost has been desired, but the production method according to the above-mentioned patent of the present applicant is It was not always optimal for such demands.

[0015]

The present invention has been made in view of the above circumstances, and an object of the present invention is to produce a purified gas having a predetermined purity by exhibiting higher gas separation efficiency. An object of the present invention is to provide a simpler method for producing a gas separator, which can produce the gas separator that can be obtained. As a result of reviewing each step of the conventional manufacturing method and conducting research in order to meet the demand of the market, it was found that the above-mentioned object can be achieved by the means shown below.

[0016]

That is, according to the present invention, there is provided a method for producing a gas separator, which comprises depositing a metal having gas separation ability on a porous substrate, wherein at least one of the porous substrates is An activation step in which one surface is contacted with a solution containing an activated metal on one surface of a porous substrate by immersing one surface in a solution containing an activated metal without pressure difference from the other surface. By immersing one surface of the porous substrate in a solution containing a metal having gas separation ability with a pressure difference from the other surface, the surface of the porous substrate contains metal having gas separation ability A method for producing a gas separator, characterized by comprising: a chemical plating step of depositing a solution, and forming a film of a metal having gas separation ability while blocking microscopic defects on the surface of the porous substrate. To be done. Since the work of creating a pressure difference between the one surface and the other surface of the porous substrate is performed only by the chemical plating process, which has a smaller number of processes, the manufacturing process is simpler than that of the conventional manufacturing method. Become.

In the present invention, the metal having gas separation ability is preferably palladium or an alloy containing palladium. Further, the film thickness of the formed metal having gas separation ability is preferably about 1 to 5 μm. The gas separation ability of the gas separator produced according to the present invention can realize about 99 to 99.9% as the purity of the specific component gas obtained by the separation.

[0018]

Embodiments of the method for producing a gas separator of the present invention will be specifically described below.
The present invention is not construed as being limited to these, and various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the present invention.

A method for producing a gas separator according to the present invention is a method for producing a gas separator in which a metal having gas separation ability is formed on a porous substrate to obtain a purified gas having a predetermined purity. While defining the film forming conditions of the metal having the gas separation ability in the minimum required gas separator, and keeping in mind that the conditions can be stably realized, the manufacturing process is simplified.
Therefore, it is intended to improve throughput and reduce manufacturing cost.

In the present invention, in order to meet this purpose, at least one activation step of immersing one surface of the porous substrate in a solution containing an activation metal without causing a pressure difference from the other surface, A chemical plating step in which one surface of the porous substrate is immersed in a solution containing a metal having gas separation ability with a pressure difference from the other surface, and the metal having gas separation ability is porous. It is characterized in that a film is formed while blocking minute defects on the surface of the substrate.

For example, as a purified gas, a purity of 99 to 9
In order to efficiently obtain about 9.9% hydrogen, in order to improve the hydrogen gas permeation rate of the gas separator, a metal having a hydrogen gas separation ability, for example, a palladium film having a thickness of about 2 μm and a porous palladium film is used. The depth of penetration into the substrate is 1-2 μ
It is preferably about m. However, the manufacturing method according to the present applicant's Japanese Patent No. 3213430 was not necessarily optimal for such a request, especially for a request for controlling the penetration depth to be shallow as 1 to 2 μm. Further, in order to realize the above requirements, it is necessary to further improve the yield.

As a reason for this, in the above-mentioned patent of the present applicant, the pressure difference between one surface and the other surface of the porous substrate is controlled in both the activation and chemical plating steps, but the plating is deposited shallowly. The delicate pressure control for this is not easy, and the thickness of palladium and the depth of penetration of palladium into the porous substrate are likely to vary.

In addition, the activation step generally needs to be dipped in a plurality of chemicals, and may include 10 to 20 steps including a washing step during chemical dipping. Therefore, it is more complicated to perform the activation step while applying a pressure difference between one surface and the other surface of the porous substrate, and more specifically, suctioning from one surface of the porous substrate. , Cause a delay in cycle time.

In the present invention, depressurization treatment is not performed in the activation step. In this case, the activation depth, that is, the depth at which the activated metal penetrates into the porous substrate is automatically 1 to 2 μm.
m. Therefore, the pressure difference between the one surface and the other surface of the porous substrate in the next chemical plating step is not particularly controlled, and for example, even if the plating solution containing palladium penetrates deeply into the porous substrate, it is active to precipitate. The depth is 1 to 2 μm, which is the converted portion.

According to the present invention, the pressure difference between one surface and the other surface of the porous substrate is usually reduced by only one step of impregnating with a plating solution containing a metal having gas separation ability, for example, palladium. It can be controlled, and the work is simpler than the manufacturing method according to the above-mentioned patent of the applicant,
The cycle time can also be shortened. Therefore, it is possible to manufacture the gas separator at a lower cost, and it is easy to be accepted by the market that desires to improve the gas separation efficiency rather than the pursuit of purity. In addition, it can be linked to the unprecedented demand stimulation.

The predetermined purity of the purified gas that can be realized in the present invention is approximately 99 to 99.9%. According to the present invention, in order to obtain a purified gas of this purity, the film thickness of the formed metal having gas separation ability is approximately 1 to 5 μm.
Has been confirmed to be good.

Hereinafter, each manufacturing step of the method for manufacturing a gas separator according to the present invention will be described in detail with reference to one embodiment thereof. The method for producing a gas separator of the present invention includes at least an activation step and a chemical plating step.
In the activation step, it is not necessary to generate a pressure difference between one surface and the other surface of the porous substrate, as described above. Both may be immersed in a solution containing an activated metal under atmospheric pressure, whereby the solution may be brought into contact with the surface of one surface of the porous substrate. With such a means of only contacting, the activated metal adheres to the surface of the porous substrate and the surface of the small holes opened on the surface of the porous substrate to an extremely shallow inside by the hydraulic pressure of the solution. In the next chemical plating step, the metal having gas separation ability is deposited on the portion where the activated metal is attached.

In this activation step, if one surface is immersed in the solution containing the activated metal, the other surface on the opposite side need not be immersed in the solution. As the activated metal, a compound containing a divalent palladium ion can be preferably used. Specifically, the activation step can be performed by alternately immersing the porous substrate in a hydrochloric acid aqueous solution of palladium chloride and a hydrochloric acid aqueous solution of tin chloride.

In the next chemical plating step, electroless plating is performed using a plating solution containing at least a metal having gas separation ability and a reducing agent to attach the metal having gas separation ability to the small holes of the porous substrate. As a result, the metal having gas separation ability fills and closes the small holes. In this chemical plating step, one side treated in the activation step is treated.
For example, the solution used in the activation step can be replaced with an appropriate plating solution.

In this chemical plating step, one side of the porous substrate is reduced so that the pressure applied to the one side is larger than the pressure on the other side of the porous substrate, and at least the metal having gas separation ability is reduced. It is preferable to immerse it in a plating solution containing the agent. For example, a tubular porous substrate can be used, the outside of which is immersed in the plating solution, and the inside of the tube can be pulled by, for example, a vacuum pump. or,
It is also possible to use a tubular porous substrate, immerse the outside in a plating solution, apply pressure to this solution, and keep the inside of the tube at a constant pressure. In any case, it is possible to reverse the inside and outside of the tube and immerse the plating solution inside the tube to change the pressure.

By creating a pressure difference between one surface and the other surface of the porous substrate, it becomes easy to infiltrate the plating solution into the small holes opened on the surface of the porous substrate. Then, the portion to which the activated metal is attached in the previous activation step is electroless plated. By adjusting the immersion time in the chemical plating process, the temperature of the plating solution, the pressure difference between the two surfaces applied to the porous substrate, etc., the depth at which the metal having gas separation ability penetrates from the surface of the porous substrate can be adjusted. It is possible.

For hydrogen separation, a known chemical plating solution containing, for example, palladium is used, and for oxygen separation, a known chemical plating solution containing, for example, silver nitrate, EDTA, aqueous ammonia and hydrazine is used. Can be used.

When producing a gas separator for hydrogen separation, after chemical plating of palladium, silver is further chemically plated on the surface of the electrodeposited palladium, and then heat treatment is performed so that the palladium and silver are separated from each other. It is preferable to diffuse and alloy palladium and silver.

An embodiment of the gas separator obtained by the method for producing a gas separator according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a gas separator according to the present invention. The gas separator 1 has a porous substrate 2 and a metal 3 having gas separating ability. Since the porous substrate 2 is porous, it has a large number of small holes 5 inside.
Some of the small holes 5 are open to the surface 6 of the porous substrate 2. In the gas separator 1 obtained by the present invention, the surface 6 of the porous substrate 2 which is in contact with the gas separation membrane 4 among the small holes 5 in which the metal 3 having the gas separating ability is opened in the surface 6 of the porous substrate 2. Only the small holes 5 in the vicinity,
The metal 3 having gas separation ability is filled and closed.

The material used as the porous substrate 2 is preferably one that does not react with the source gas, and specifically, alumina, silica, silica-alumina, mullite,
In addition to cordierite, zirconia, carbon, porous glass and the like can be used. The thickness of the porous substrate 2 is not particularly limited. It suffices to maintain sufficient mechanical strength in the environment of use.

The porous substrate 2 has a large number of minute pores 5 which are three-dimensionally continuous. The pore diameter of the pores 5 is preferably 0.003 to 2 μm, and 0 It is more preferably 0.1 to 1 μm or less.
This is because when the pore size is less than 0.003 μm, the resistance when the gas passes increases. On the other hand, if the pore diameter exceeds 2 μm, it is difficult to block the small holes 5 by chemical plating of the metal 3 having gas separation ability, which is not preferable.

Further, it is preferable that the small holes 5 of the porous substrate 2 have uniform hole diameters. As a result, in the chemical plating step, it is easy to allow the plating solution to uniformly enter the small holes near the surface 6 of the porous substrate 2 without leakage, and the small holes 5 in which the metal 3 having gas separation ability is not filled are generated. Can be avoided.

Further, the shape of the porous substrate 2 is preferably a surface, and the surface includes a flat surface and a curved surface, and
Naturally, the tube shape corresponding to the shape where the curved surface is closed is included. In the case of a tubular shape, the shape of the tubular cross section is arbitrary, but a circular shape is easy to obtain and is preferable. Further, the shape of the gas separator 1 or the shape of the porous substrate 2 may be a plate shape, and can be any shape depending on the purpose of use.

The metal 3 having gas separation ability is selected depending on the gas to be purified. For example, for hydrogen gas purification, palladium, an alloy containing palladium as a main component, or an alloy containing palladium. In order to separate oxygen, a thin film of silver or an alloy containing silver as a main component, an organic material thin film, or the like is used.

In the gas separator 1 according to the present invention, the metal 3 having the gas separating ability to fill the small holes near the surface 6 of the porous substrate 2 has a gas separating function, so that the metal 3 having the gas separating function serves as the electrode. The thickness can be reduced, and the gas separation efficiency of the gas separator 1 can be further increased.

In the gas separator 1 according to the present invention, the depth at which the metal 3 having a gas separating ability penetrates into the porous substrate 2 can be defined as necessary, but the depth of the porous substrate 2 is almost the same. It may be 1 to 5 μm from the surface 6. This depth is 1
If it is smaller than μm, the small holes may not be sufficiently blocked by the metal 3 having gas separation ability, and the possibility that the raw material gas leaks to the purified gas side increases. Moreover, the gas separation membrane 4 is easily separated from the surface 6 of the porous substrate 2. On the other hand, if the depth is larger than 5 μm, the gas separation efficiency is lowered, which is not preferable.

Further, in the gas separator 1 according to the present invention, the metal 3 having the gas separating ability for filling and closing the small holes 5 near the surface 6 of the porous substrate 2 forms the gas separation membrane 4. It is more preferable if the metal and the metal having gas separation ability are continuously formed. This is because the adhesion between the gas separation membrane 4 and the porous substrate 2 is further improved, and the gas separation membrane 4 is less likely to be peeled from the surface 6 of the porous substrate 2.

When the metal 3 having gas separation ability is made of a palladium alloy, Japan Membr
one Science, 56 (1991) 315-3
25: "Hydrogen Permeable Pa
lladium- Silver Alloy Mem
Brane Supported on Porous
As described in "Ceramics" and JP-A-63-295402, the content of metals other than palladium is preferably 10 to 30% by mass. The main purpose of alloying palladium is hydrogen embrittlement of palladium. In order to prevent hydrogen embrittlement and to improve separation efficiency at high temperature, it is preferable that silver is contained as a metal other than palladium because it contributes to prevention of hydrogen embrittlement of palladium.

[0045]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. Example 1 First, the porous substrate was washed. A porous α-alumina tube having a cylindrical shape with an outer diameter of 10 mm, an inner diameter of 7 mm, and a length of 300 mm, and a micropore diameter of 0.1 μm,
Used on a porous substrate, the porous tube was washed with water and then dried. Next, as a degreasing treatment, Okuno Pharmaceutical OPC3
A solution containing 10% of 70 was kept at 70 ° C., immersed for 5 minutes, and then washed with water.

Next, the porous substrate was activated.
This porous α-alumina tube was immersed in a solution containing 1% OPC pre-dipping for 2 minutes. Next, a solution containing 5% of each of Okuno Seiyaku's inducers A and B was kept at 50 ° C., immersed for 5 minutes, and then washed with water. Next, it was immersed for 5 minutes in a solution containing 15% of KUSTER MU made by Okuno Seiyaku. Next, it was immersed for 1 minute in a solution containing 3% of KUSTER MU made by Okuno Seiyaku, and washed with water. Next, it was immersed in a solution containing 0.05% of hydrazine for 1 minute.

Since the activation process can be performed by the following different means, only the introduction will be given. That is, porous α
-Set the outer surface of the alumina tube to 0.1% SnCl ₂ · 2H ₂ O.
Immerse in a 0.1% hydrochloric acid aqueous solution containing mass% for 1 minute. The outer surface of the tube was then treated with 0.01% PdCl ₂ .
Immerse in a 0.1% hydrochloric acid aqueous solution containing mass% for 1 minute. This dipping treatment is repeated with both aqueous hydrochloric acid solutions so that each aqueous hydrochloric acid solution is dipped 10 times. The activation process can also be performed by such means.

Next, palladium was chemically plated.
In 1 liter of deionized water, [Pd (NH ₃ ) ₄ ] Cl
₂ · H ₂ O (5.4 g), 2Na · EDTA (67.2)
g), ammonia water having an ammonia concentration of 28% (651.
3 ml) and an aqueous solution containing H ₂ NNH ₂ · H ₂ O (0.64 ml) were prepared, and the outer surface of the activated α-alumina tube was treated with the above aqueous solution whose temperature was controlled to 50 ° C. The tube was immersed, while the inside of the tube was pulled by a vacuum pump to reduce the pressure. By changing this immersion time, the thickness of the thin film coating the surface of the porous substrate and the depth of penetration into the inside of the porous substrate were adjusted. Then, the yield investigation was conducted on the penetration depth of the deposited palladium. The penetration depth was adjusted to 1.5 mm, and the accuracy of the penetration depth when the thickness of the thin film was adjusted to 2 μm was tested on 20 test bodies. A porous substrate having a depth within 1.5 ± 0.5 mm was regarded as acceptable and the yield was determined.

Next, silver was electroplated and adjusted so that the weight ratio of palladium to silver was 80:20.
Finally, by holding at 900 ° C. for 1 hour, heat treatment was carried out to mutually diffuse palladium and silver to alloy palladium with silver to obtain a gas separator.

Regarding the gas separator thus obtained,
An airtight test was conducted. Argon gas was introduced to the outside of the alumina tube, the pressure was maintained at 900 kPa, and the amount of gas leaking inside the alumina tube was measured.

A hydrogen separation test was conducted on the gas separator. A mixed gas 17 composed of 80% by volume of hydrogen and 20% by volume of carbon dioxide was used as a raw material gas. A schematic diagram of the test apparatus is shown in FIG. First, the chamber 7 was heated to 500 ° C. Then, the mixed gas 17 having a pressure of 900 kPa was introduced at a rate of 2 N liter / min outside the gas separator 16. Also, inside the gas separator 16, a pressure of 100
Using kPa argon as the carrier gas 18, 0.1
Introduced at N liter / min. The purified gas 19 thus obtained was quantitatively analyzed by gas chromatography, and the gas permeation rate of the purified gas 19 and the hydrogen concentration in the purified gas 19 were examined.

Further, the gas separator was subjected to a heat cycle test. The gas separator in a hydrogen atmosphere was heated from room temperature to 500 ° C and then cooled to room temperature. This heating / cooling cycle was set as one cycle, and 20 cycles were performed. Table 1 shows the test results of these airtightness test, gas separation test and heat cycle test.

[0053]

[Table 1]

(Comparative Example 1) In the step of activating the porous substrate, the inside of the α-alumina tube was depressurized in each step of dipping it in each solution, and in the palladium chemical plating step, the gas separator was not depressurized. Got Since there is no pressure reduction in the palladium chemical plating step, neither the film thickness of the thin film covering the surface of the porous substrate nor the penetration depth into the porous substrate was adjusted, and no yield survey was conducted. Other than that, it processed on the same conditions as Example 1. The results are shown in Table 1.

(Comparative Example 2) In both the step of activating the porous substrate and the step of palladium chemical plating,
A gas separator was obtained without depressurizing the inside of the α-alumina tube.
Since there is no pressure reduction in the palladium chemical plating step, neither the film thickness of the thin film covering the surface of the porous substrate nor the penetration depth into the porous substrate was adjusted, and no yield survey was conducted. Other than that, it processed on the same conditions as Example 1. The results are shown in Table 1.

Comparative Example 3 In both the step of activating the porous substrate and the step of palladium chemical plating,
The inside of the α-alumina tube was depressurized to obtain a gas separator. The film thickness of the thin film covering the surface of the porous substrate was adjusted to 2 μm by reducing the pressure in the palladium chemical plating step. Further, the penetration depth of the porous substrate was adjusted to 1.5 mm, and the accuracy of the penetration depth of the deposited palladium was tested on 20 test bodies. The depth inside the porous substrate is 1.5 ±
Those that were within 0.5 mm were accepted and the yield was determined. Other than that, it processed on the same conditions as Example 1. The results are shown in Table 1.

(Discussion) Comparing the results of Example 1 and Comparative Example 2, palladium was introduced to the inside of the porous substrate by depressurizing the inside of the α-alumina tube in the activation treatment step or the chemical plating step. It can be seen that it can be attached. It can be seen that the airtightness of the gas separator and the hydrogen purity in the purified gas are improved by increasing the filling depth from the surface of the palladium alloy. Also, in the thermal cycle test, the gas separation membrane becomes difficult to peel off from the porous substrate,
It can be seen that the adhesion is improved.

In the activation treatment step, it is necessary to immerse in a plurality of chemicals, the number of steps is approximately 4 to 20, and it is complicated to perform the depressurization treatment in each step.
In the above, since the same effect as in Comparative Example 1 can be obtained by performing the depressurization treatment only in the one step of impregnating with the plating solution, the steps can be omitted.

By comparing the yields of Example 1 and Comparative Example 3, the precipitation depth of palladium in the porous substrate was determined to be 1 to 2
The present invention (Example 1) is superior in the delicate film thickness control for making the thickness μm. In both the step of activating the porous substrate and the step of palladium chemical plating, if the inside of the α-alumina tube is depressurized, the variation in the palladium deposition depth will increase and the yield will decrease. For example, if the palladium penetrates too deeply, the gas permeation rate decreases, or if a shallow portion is generated, it leads to deterioration of airtightness. Therefore, this decrease in yield is not preferable, and only one side of the porous substrate is immersed in a solution containing a metal having gas separation ability with a pressure difference from the other side only in the palladium chemical plating step to form a porous substrate. It is useful to control the depth of palladium deposition in the substrate to a desired depth.

[0060]

EFFECT OF THE INVENTION In the method for producing a gas separator of the present invention,
Only by the chemical plating process using a smaller number of chemicals, one surface of the porous substrate is immersed in a plating solution so that the pressure applied to the one surface is larger than the pressure on the opposite surface of the porous substrate. As a result, in the vicinity of the surface of the small hole opened on the surface of one surface of the porous substrate, the metal having gas separation ability is filled in the small hole to be blocked. Since it is not necessary to provide a pressure difference between one surface and the other surface of the porous substrate in the activation process using a plurality of chemicals, the work can be simplified and the cycle time of the process can be shortened to improve the throughput.

Furthermore, in the gas separator obtained by the method for producing a gas separator of the present invention, preferably, the depth at which the metal having gas separating ability penetrates into the porous substrate is porous. 1-2 μm from the surface of the substrate,
The thickness of the gas separation membrane is preferably 1-5 μm.
A gas separator satisfying such a condition is excellent in gas separation efficiency and can contribute to reduction in equipment cost and operation cost of a gas separation device using this gas separator.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a gas separator obtained by the method for producing a gas separator according to the present invention.

FIG. 2 is a schematic diagram of a hydrogen separation test apparatus according to the method for producing a gas separator of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gas separator, 2 ... Porous substrate, 3 ... Metal having gas separation ability, 4 ... Gas separation membrane, 5 ... Small holes, 6 ... Surface, 7 ...
Vacuum chamber, 8 ... Introduction tube, 10 ... Introduction tube, 15 ... O
Ring, 16 ... Gas separator, 17 ... Mixed gas, 18 ... Carrier gas, 19 ... Purified gas.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C23C 18/31 C23C 18/31 A 18/42 18/42 F term (reference) 4D006 GA41 HA21 MA02 MA06 MB04 MC02X MC03X NA05 NA45 NA49 PA01 PB18 PB66 4G040 FA06 FB09 FC01 FE01 4K022 AA37 AA41 CA04 CA13 CA16 DA01 DB30

Claims (2)

[Claims] 1. A method for producing a gas separator, which comprises depositing a metal having gas separation ability on a porous substrate, wherein at least one surface of the porous substrate is accompanied by a pressure difference from the other surface. Without, an activation step of immersing in a solution containing an activated metal, one surface of the porous substrate, with a pressure difference from the other surface, immersed in a solution containing a metal having gas separation ability And a chemical plating step for allowing the metal having gas separation ability to be deposited on one surface of the porous substrate while blocking micro defects in the porous substrate. Body manufacturing method. 2. The metal having gas separation ability is palladium or an alloy containing palladium.
The method for producing a gas separator according to item 1.