JPH05317662A - Hydrogen separation membrane and its production - Google Patents

Abstract

PURPOSE:To easily produce a hydrogen separation membrane with a short time and a small labor, excellent in heat resistance, mechanical strength, and separation ability at a high temp. and having good machinability, capable of recovering high purity hydrogen. CONSTITUTION:The hydrogen separation membrane 10 is obtained by sticking and forming the alloy membrane 12 composed of palladium and silver having 1-50mum thickness on one face of a stainless steel-made metallic supporting body 11 perforated by etching to form many narrow pores of 10-500etam pore diameter.

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 for diffusing and separating hydrogen in a hydrogen-containing gas and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, hydrogen gas is a natural gas, LPG,
It is produced by a steam reforming method using hydrocarbons such as naphtha or methanol as a raw material, and is also produced from off-gas for petroleum refining. As a method for purifying and recovering hydrogen from the hydrogen-containing gas produced by the above method, a PSA method (Pressure Swing) using an adsorbent is used.
There are methods for separating and removing impurities by means of absorption, etc., and methods for diffusing and separating hydrogen with an organic or inorganic hydrogen separation membrane. Among them, the membrane separation method is energy-saving, separation efficiency, simple configuration and operation of the device. It is attracting attention from the viewpoint of ease of use.

Hydrogen separation membranes used in the membrane separation method include organic polymer membranes such as polyimide and polysulfone, inorganic porous membranes such as porous glass and porous ceramics,
And palladium or palladium alloy film.
Among them, the organic polymer membrane has a problem in heat resistance and reduction in separation efficiency at high temperature, and also has a defect that the separation efficiency is low even in the inorganic porous membrane, and also in the palladium or palladium alloy membrane, there is heat resistance. Further, although hydrogen of extremely high purity can be obtained, there are problems such as mechanical strength and difficulty of thin film manufacturing technology.

As a hydrogen separation membrane in which the mechanical strength of the above palladium or palladium alloy membrane is increased, Japanese Patent Laid-Open No. 62-1
21616, JP-A-62-273030,
Japanese Patent Laid-Open No. 63-171617 discloses a porous glass,
Membranes in which a palladium or palladium alloy membrane is deposited on the surface of an inorganic porous support such as porous ceramics or porous aluminum oxide are disclosed, and in these publications, a method for producing the hydrogen separation membrane is disclosed. Is also described.

In the method for producing a hydrogen separation membrane described in the above publication, the method disclosed in Japanese Patent Laid-Open No. 62-121616 discloses a palladium or palladium alloy membrane on the surface of an inorganic porous support having a thickness of about 1 mm. Is deposited by a vapor phase chemical reaction or a vacuum deposition method, but it has a drawback that the equipment is complicated and requires a high-level manufacturing technique, and that it takes time to manufacture a thick film. Further, in the method disclosed in Japanese Patent Laid-Open No. 62-273030, after the surface of the inorganic porous material is chemically activated, the palladium-based film is deposited by the chemical plating method. And there is a drawback that it takes time. Further, in the method disclosed in Japanese Patent Laid-Open No. 63-171617, for example, after anodizing the metallic aluminum,
Metallic aluminum is dissolved and removed by etching method to a thickness of 5
A porous aluminum oxide film having a thickness of about 0 μm is manufactured, and palladium or a palladium alloy is deposited on the film by a sputtering method, and then palladium is further supported by an aqueous solution of a palladium salt, which is very time-consuming and requires a high degree of performance. There are drawbacks that require membrane technology.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and since it is supported by a metal support in which pores having a predetermined pore diameter are perforated, heat resistance and mechanical properties are improved. Hydrogen separation membrane that can recover high-purity hydrogen with high mechanical strength, has excellent separation performance even at high temperatures, and has good processability in a short time and with little labor. It is an object of the present invention to provide a membrane and a manufacturing method thereof.

[0007]

The present invention has a hole diameter of 10 to 5
An alloy film (hereinafter sometimes referred to as "palladium alloy film") made of palladium and another metal having a film thickness of 1 to 50 μm is adhered and formed on one surface of a metal support in which a large number of 00 μm pores are formed by etching. The present invention provides a hydrogen separation membrane.

The present invention also provides a method for producing the hydrogen separation membrane, which comprises the following steps. (1) A first step in which thin films of palladium and another metal are alternately laminated on one surface of a metal support by electroplating. (2) A second step of forming pores on the other surface of the metal support obtained in the first step by an etching method. (3) A third step of heat-treating the palladium-other metal thin film layer of the metal support obtained in the second step at 500 to 900 ° C. for alloying.

An example of the hydrogen separation membrane of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a part of a hydrogen separation membrane manufacturing process, and FIG. 1 (A) is for explaining a state in which a palladium-other metal thin film layer is deposited / formed on one surface of a metal support. 1 is an enlarged cross-sectional configuration diagram, FIG.
It is an expanded sectional lineblock diagram of the hydrogen separation membrane of the present invention obtained by etching the other side of the metal support of (A).

The hydrogen separation membrane 10 of the present invention has a pore size of 10-5.
One side 11 of the metal support 11 in which a large number of pores h of 00 μm, preferably 50 to 200 μm are perforated by etching.
The palladium alloy film 12 having a film thickness of 1 to 50 μm, preferably 5 to 30 μm is deposited and formed on a (see FIG. 1B).

Here, as the material of the metal support 11,
Stainless steel, nickel, copper alloy, nickel base alloy, iron −
Examples include metals such as nickel alloys. Hydrogen separation membrane 10
By adopting the metal support 11 as the support of
Even if the hydrogen separation treatment is performed at a temperature of 200 ° C. or higher, the hydrogen separation membrane 10 and the mounting member (frame or the like) (not shown) can be connected by means such as welding, so that the sealing property does not deteriorate. When an inorganic material such as ceramics is used instead of the metal support 11, there is a disadvantage that electroless plating with a low film formation rate is necessary because electroplating cannot be directly performed. This metal support 1
The pore diameter d of the large number of pores h perforated in 1 is 10 to 500 μm.
m, preferably 50 to 200 μm. When it is less than 10 μm, the flow resistance becomes large, while when it exceeds 500 μm, the palladium alloy film 12 as the adherend film is depressed and pinholes are easily generated. The perforation density of the pores h is
It is preferably about 150 to 3,000 pieces / cm ² .

The thickness of the metal support 11 is usually 10-5.
00 μm, preferably about 50 to 200 μm, and 1
If it is less than 0 μm, the mechanical strength of the support is weak and it is not practical, while if it exceeds 500 μm, it is necessary to etch the perforations having a large pore size, which is not preferable. The shape of the metal support 11 may be tubular as well as plate-like as shown in FIG. 1, and any shape may be adopted depending on the purpose.

On the other hand, the palladium alloy film 12 is a thin film of an alloy containing palladium as a main component, and is composed of palladium, a Group VIII element (for example, cobalt and nickel) other than palladium, and an IB group (for example, copper). Silver, gold), and an alloy with at least one other metal selected from the group IIIB (eg, yttrium), preferably an alloy of palladium and silver. The content of metals other than palladium in the palladium alloy film 12 is 1
˜50% by weight, preferably 10 to 30% by weight. The main purpose of alloying palladium is to prevent hydrogen embrittlement of palladium and to improve the separation efficiency at high temperatures. If the content of other metals other than palladium is less than 1% by weight, the prevention of hydrogen embrittlement of palladium and high temperature The effect of improving the separation efficiency decreases,
On the other hand, if it exceeds 50% by weight, the hydrogen permeation rate becomes too slow, which is not practical.

The total thickness of the palladium alloy film 12 is 1 to 50.
μm, preferably 5 to 30 μm. If the total thickness of the palladium alloy film 12 is less than 1 μm, pinholes are likely to occur in the alloy film 12 and normal deposition becomes difficult, and the purity of the separated hydrogen is lowered. The transmission speed is too slow to be practical.

Next, the method for producing the hydrogen separation membrane of the present invention will be described.
This will be described with reference to FIG. First, in the first step, thin films of palladium and another metal are alternately laminated on one surface 11a of the metal support 11 by electroplating.

Then, palladium and another metal are alternately laminated and deposited on one surface 11a of the metal support 11 thus electroless plated by the electroplating method. In this electroplating method, a commonly used electroplating apparatus is used. When plating a thin film of palladium, an aqueous solution in which a palladium salt and an electrolyte are dissolved is used as an electroplating solution, and one side of a metal support 11 is connected to the minus side in an electrolytic bath filled with the electroplating solution. 11a and a platinum plate connected to the positive side are immersed and a direct current power source is energized to form a deposit. Examples of this electroplating solution include, for example, the following, but are not limited to this composition, and may be a composition in which a palladium film or another metal film is laminated and deposited by an electroplating method. There is no particular limitation.

For Pd film; [Pd (NH ₃ ) ₄ ] Cl ₂ ·
2H ₂ O; 30 g / l, NH ₄ Cl; 60 g / l, for Ag membrane; AgCN; 36 g / l, KCN; 60 g /
l, K ₂ CO ₃ ; 15 g / l for Ni film; NiSO ₄ ; 240 g / l, NiCl ₂ ; 4
5 g / l, H ₃ BO ₃ ; 30 g / l

For Co film; CoSO ₄ ; 300 g / l, N
H ₄ Cl; 20 g / l, H ₃ BO ₃ ; 15 g / l, for Cu film; CuSO ₄ .5H ₂ O; 250 g / l, H ₂
SO ₄ ; 75 g / l

The current density by this electroplating method varies depending on the properties of the electroplating solution, but is 0.1-3 A / d.
m ² . Further, the total thickness of the thin films (palladium film and other metal film) can be set to the above-mentioned predetermined film thickness by making the electroplating time variable.

The palladium alloy film 12 is formed by alternately depositing palladium and another metal, for example, a palladium thin film is first formed by electroless plating, and a thin film of an alloyed metal is laminated on the thin film. It may be deposited or may be deposited in the reverse process, and it is also possible to use the impregnation method, adsorption method, ion exchange method, vacuum deposition method (PVD), vapor phase chemical reaction method (CVD), etc. Is.

Next, in the second step, fine holes are formed in the other surface 11b of the metal support 11 obtained in the first step by an etching method. In this case, as a method for etching the other surface 11b of the metal support 11, for example, a negative resist (not shown) is applied to the one surface 11b by a spin coating method or the like, and after baking, a pattern corresponding to the pores h is formed. It is implemented by irradiating light such as ultraviolet rays through a mask (not shown), developing, post-baking, and further etching to remove the remaining resist film.

That is, prior to applying the resist,
In order to secure the adhesiveness of the resist to the metal support 11, as a pretreatment, for example, alkali cleaning with 10% sodium hydroxide aqueous solution at 70 ° C., water washing, neutralization, water washing, and drying are performed to clean the resist coated surface. To convert. The resist to be used may be a water-soluble type resist such as casein type, PVA type, etc., and an acrylic polymer solvent-soluble type negative type resist, but in the present invention, a negative type acrylic polymer [Tokyo Ohka Kogyo ( Co., Ltd., PMER-N40DP] was used. As a method for applying the resist to the cleaned metal support 11, a roll coating method, a spin coating method, a dip pulling coating method, or the like is used, and a dip pulling method is preferable.

The thickness to be applied is determined by the resist viscosity and pulling speed, but from the viewpoint of resolution during exposure, it is 1
The thickness is preferably 5 μm or less, and more preferably 3 μm or more from the viewpoint of acid resistance during etching and maintaining the strength of the resist film.
Therefore, the pulling speed may be determined so that the dry film thickness is in the range of 3 to 15 μm. When the resist to be applied contains, for example, an acrylic polymer as a main component and a solid content concentration of 30% and a solvent as a main component such as toluene of 70%, the resist is exposed to hot air at 70 ° C. before exposure. And dry for 10 minutes or more to remove the solvent content by drying. In this way, a film mask on which the pattern of the preformed pores is imaged is brought into close contact with the support side of the resist film coated on the metal support 11, and ultraviolet rays having a wavelength of about 375 nm generated by an ultra-high pressure mercury lamp are attached. 60
-70 seconds (irradiation amount = 300-350 mJ).

In the fine hole pattern portion image-formed on the resist surface on the metal support 11 side in the exposure step, the resist is dissolved and removed only in the etching perforation portion (unexposed portion) in the next development step, and the metal surface is exposed. To be done. The conditions for this development are as follows: Alkaline-only chemical solution [Tokyo Ohka Kogyo Co., Ltd.,
N-A5] at 25 ± 2.5 ° C. The resist film on which the pattern of holes to be opened is formed by this developing step is post-baked prior to the etching step in order to further improve the acid resistance strength, coating adhesion and coating strength of the film. The heat source for this post-baking may be either hot air or far-ultraviolet radiation, but the temperature is 1
It is carried out at 00 to 120 ° C. for 15 to 30 minutes. If the temperature is less than 100 ° C, thermal polymerization is insufficient and sufficient coating performance cannot be obtained.
If it exceeds 20 ° C, the film becomes brittle.

After that, the etching process is started, but the etching solution is usually a second chloride of 42 to 47 ° Be (Baume).
The iron solution is sprayed onto the surface of the object. In this case, from the viewpoint of mass productivity, it is preferable to spray the upper and lower parts by a horizontal transfer method. The liquid temperature is between 45 and 65 ° C. The control of the etching rate is determined by the transport speed. In addition, to stabilize the etching conditions,
To control the accuracy, use water or hydrochloric acid,
The pH value is also controlled. By this etching, the metal support 11 perforated from one surface is washed with water to wash the etching solution, and after removing the residue of the resist film used for masking from the surface, it is sufficiently washed to obtain a product. The stripping solution is usually prepared by immersing a 5 to 10% aqueous sodium hydroxide solution in a solution heated to 50 to 70 ° C. to remove the resist film by swelling and stripping.

By this second step, as shown in FIG. 1 (B), a large number of fine holes h, which are through holes, are punched from the other one surface 11b side of the metal support 11. In addition, in FIG. 1B, the symbol w indicates the palladium alloy film 12 and the metal support 1.
1 is the shortest contact distance, and this distance is usually 100-
It is about 1,000 μm.

Further, in the third step, the palladium-other metal thin film layer of the metal support obtained in the second step is added to 50
It heat-processes at 0-900 degreeC and alloys. The thin film deposited in the first step is a film in which palladium and another metal are laminated, and in order to form an alloyed palladium alloy film,
The hydrogen separation membrane 10 obtained in the step is heat-treated in an electric furnace or the like to form metals by mutual diffusion. The heat treatment temperature is 500 to 900 ° C., preferably 6
It is from 00 to 800 ° C, and mutual diffusion of metals does not occur below 500 ° C, while when it exceeds 900 ° C, the diffusion and mixing from the metal support 11 becomes so large that it cannot be ignored.
Further, the plating layer is melted during the heat treatment to generate voids, which may impair the function of the film, which is not preferable. The heat treatment time is preferably 0.1 to 10 hours.

Next, an example of the hydrogen separation method using the hydrogen separation membrane 10 will be described with reference to FIG. Here, FIG.
FIG. 4 is a schematic process diagram of a hydrogen separation method using the hydrogen separation membrane of the present invention. In FIG. 2, the separator S is composed of a hydrogen separator 20 incorporating the hydrogen separation membrane 10 of the present invention and a heater 30 covering the hydrogen separator 20. Here, the hydrogen separation membrane 10 is horizontally arranged in the hydrogen separator 20 such that the metal support 11 is located below and the palladium alloy membrane 12 is located above. In order to separate hydrogen gas from the raw material gas containing hydrogen using this separator S, the raw material gas G1
Is introduced into the upper part 21 of the hydrogen separator 20. Raw material gas G1
The hydrogen gas inside is the palladium alloy membrane 1 of the hydrogen separation membrane 10.
2 and is taken out as a permeated gas H. On the other hand, a non-permeable gas G2 obtained by separating hydrogen gas from the raw material gas G1
Is taken out of the system from above the hydrogen separator 10.

The conditions for this hydrogen separation are that the temperature is room temperature to 600 ° C., the pressure in the upper portion 21 of the hydrogen separator 20 is atmospheric pressure or higher, and there is a pressure difference from the permeate side.

[0030]

The hydrogen separation membrane of the present invention is formed by depositing a palladium alloy on a metal support in which pores having a specific pore size are perforated, and therefore has good sealing properties, heat resistance, and mechanical strength. Excellent in recovery of high-purity hydrogen, excellent separation performance even at high temperatures, and good processability.
Manufacturing cost is low. Further, in the method for producing a hydrogen separation membrane of the present invention, first, palladium-other metal layers are alternately laminated on one surface of the metal support by an electroplating method, and pores are punched from the other surface by an etching method. By heat treatment, palladium and other metals other than palladium are mutually diffused to form a palladium alloy layer, and a separation membrane excellent in hydrogen separation ability can be manufactured at a low cost by a relatively simple process. ..

[0031]

EXAMPLES The present invention will be described in more detail with reference to examples. Example 1 Production of Hydrogen Separation Membrane One side of 200 μm thick stainless steel (SUS316) was electroplated with palladium and silver alternately. The plating bath composition used was as shown below. The bath temperature is 30
℃, current density is 1A / d for palladium plating
m ² and 0.5 A / dm ² for silver plating. The total thickness of the plating is 30 μm, and the weight ratio is palladium: silver =
Multi-layer plating was performed so that the ratio was 80:20.

Palladium plating bath composition Pd (NH ₃ ) ₄ Cl ₂・ ・ ・ 30 g / kg NH ₄ Cl ・ ・ ・ 60 g / kg H ₂ O ・ ・ ・ Bal pH ・ ・ ・ ・ ・ 9 ~ 9.5 Silver plating bath composition AgCN: 36 g / kg KCN: 60 g / kg K ₂ CO _3: 15 g / kg

Next, the etching treatment was carried out by subjecting the plated material to pre-treatment cleaning and the following conditions. Resist coating conditions Resist type: Negative type acrylic polymer [PMER-N40DP manufactured by Tokyo Ohka Kogyo Co., Ltd.] Coating thickness: 7 μm Exposure conditions Ultraviolet wavelength: 375 nm Irradiation amount: 450 mJ Etching conditions Etching solution: Ferric chloride aqueous solution (45 ° Be , 48
In this etching process, the pore diameter d of the pore h is 10
0 μm, shortest contact distance w between plating and metal support is 500
It carried out so that it might become (micrometer). Then, alloying heat treatment of plating was performed at 600 ° C. for 15 hours to obtain a hydrogen separation membrane.

Hydrogen Separation Experiment The hydrogen separation membrane 10 obtained above was mounted in the hydrogen separator 20 shown in FIG. 2, and in this step, a mixed gas (74% by volume of hydrogen, 1% by volume of CO, CH ₄ 1) was used as a raw material gas G1. Capacity%, C
O ₂ 24% by volume). The permeated gas (hydrogen gas) and the non-permeated gas were separately measured in flow rate by the gas meters M1 and M2, and were introduced into the gas chromatograph GC to analyze the gas composition.

The experimental conditions are as follows. Temperature = 400 ° C. Pressure (pressure in the upper part 21 of the hydrogen separator 20) = 8.0 kg
/ Cm ² · G mixed gas flow rate = 1.0 Nl / min Outlet pressure (pressure in lower part 21 of hydrogen separator 20) = normal pressure The experimental results were as follows. Hydrogen gas concentration in permeated gas = 100% Permeation rate = 80.0 cm ³ / cm ² / min

[0036]

EFFECTS OF THE INVENTION According to the present invention, since a metal having a large number of pores is used as a support, it has excellent heat resistance and mechanical strength, can collect high-purity hydrogen, and even at high temperature. Since a thin film of palladium or the like is formed with excellent separation performance by electroplating, a good hydrogen separation membrane can be easily manufactured in a short time with little labor.

[Brief description of drawings]

FIG. 1 is a schematic view showing a part of a hydrogen separation membrane manufacturing process, and FIG. 1 (A) is for explaining a state in which a palladium-other metal thin film layer is deposited / formed on one surface of a metal support. FIG. 1B is an enlarged cross-sectional configuration diagram of the hydrogen permeable membrane of the present invention obtained by etching the other surface of the metal support of FIG. 1A.

FIG. 2 is a schematic view of a hydrogen separation process using the hydrogen separation membrane of the present invention.

[Explanation of symbols]

 10 Hydrogen Separation Membrane 11 Metal Support 12 Palladium Alloy Membrane

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Koga 2-1, Okawa-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Sanryo Kakoki Co., Ltd. (72) Hiromitsu Hoshi, 2-8, Honshio-cho, Shinjuku-ku, Tokyo Within Japan Stainless Co., Ltd. (72) Inventor Ryoyasu Ikeda 2-12-1 Minatomachi, Joetsu City, Niigata Prefecture Within Japan Stainless Co., Ltd.

Claims (2)

[Claims] 1. A metal support having a large number of pores having a diameter of 10 to 500 μm perforated by etching has a film thickness of 1 to 1 on one side.
A hydrogen separation membrane in which an alloy membrane of 50 μm of palladium and another metal is adhered and formed. 2. The method for producing a hydrogen separation membrane according to claim 1, comprising the following steps. (1) A first step in which thin films of palladium and another metal are alternately laminated on one surface of a metal support by electroplating. (2) A second step of forming pores on the other surface of the metal support obtained in the first step by an etching method. (3) A third step of heat-treating the palladium-other metal thin film layer of the metal support obtained in the second step at 500 to 900 ° C. for alloying.