JP2002153739A - Method of manufacturing hydrogen separation membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a hydrogen separation membrane, which can manufacture a highly permeable hydrogen separation membrane at a low cost by easily forming a palladium alloy membrane in a palladium-based hydrogen separation membrane with a high yield so as to make the alloy membrane as thin as possible. SOLUTION: This manufacturing method of hydrogen separation membrane that permeates hydrogen to selectively separate it from a hydrogen-containing gas, comprises a process for cladding the surface of a porous carrier with palladium and metallic foil to be alloyed, a process for forming a palladium membrane on the surface of the metallic foil, and a process for forming a palladium alloy membrane mainly comprising palladium by heating in the reducing atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas, and more particularly, to a method for forming a thin film of an alloy mainly composed of palladium on the surface of a porous carrier. The present invention relates to a method for producing the formed inorganic hydrogen separation membrane.

[0002]

2. Description of the Related Art Hydrogen-containing gases are mainly natural gas, LP
G, naphtha, kerosene or methanol is used as a raw material and is produced by a steam reforming method or a partial oxidation method. Hydrogen is separated and recovered from a hydrogen-containing gas produced by such a method, and the recovered hydrogen is recovered. It is used for fuel cells, semiconductor production, metal refining, oil and fat production, petroleum refining, etc.

Conventionally, as a method of recovering hydrogen from a hydrogen-containing gas, a method of separating and removing impurities other than hydrogen by a solution absorption method, an adsorption method, a cryogenic separation method, or the like, or a method of recovering hydrogen by a hydrogen separation membrane is used. There is a membrane separation method of permeating and recovering the permeate, and among them, the membrane separation method has attracted attention because of its energy saving, good separation efficiency, and simple device configuration.

As the hydrogen separation membrane used in the membrane separation method, an organic polymer separation membrane such as polyimide or polysulfone, a porous ceramics separation membrane, and a palladium separation membrane such as palladium or a palladium alloy are used. Organic polymer separation membranes are limited to use in low-temperature areas such as heat resistance and reduced separation efficiency at high temperatures, and cannot directly separate and recover hydrogen from high-temperature hydrogen-containing gas, so there is a problem of low thermal efficiency. Porous ceramic separation membranes have a problem of low hydrogen separation efficiency. Compared to the above-mentioned hydrogen separation membrane, the palladium-based separation membrane has higher heat resistance and therefore can improve the thermal efficiency, and can efficiently separate and recover extremely high-purity hydrogen.

[0005] The palladium-based hydrogen separation membrane comprises a metal,
A palladium simple substance film or a palladium alloy film is formed on the surface of a cylindrical or plate-like porous carrier formed of a material such as ceramics or glass. A method of forming a palladium-based film on the surface of the substrate by a gas phase chemical reaction method or a vacuum evaporation method (Japanese Patent Application Laid-Open No. 62-121616). Chemical plating method for forming a palladium-based film (JP-A-62-2730)
No. 30), an electroplating method for forming a palladium-based film on the surface of a porous metal carrier by electroplating (Japanese Patent Laid-Open No.
No. 3,269,931) or a method in which a thin palladium-based film is formed on the surface of a porous carrier by a chemical plating method, and then a palladium-based film is laminated and formed by an electroplating method (Japanese Patent Application Laid-Open No. 5-137797). There is.

[0006]

The palladium-based membrane formed on the surface of the conventional porous carrier is formed in a thickness of about 1 to 50 μm in consideration of the strength and the hydrogen permeation rate. Since it is extremely thin, pinholes are apt to occur due to the roughness of the surface of the porous carrier, and there is a problem that the yield is poor. In order to prevent the pinhole of the membrane, the surface roughness of the porous carrier is required. It is necessary to strictly control the quality of the palladium-based hydrogen separation membrane, so that the operation is complicated and the production cost of the palladium-based hydrogen separation membrane is high. Furthermore, increasing the film thickness to increase the strength is problematic because of problems such as a decrease in transmission efficiency, an increase in manufacturing cost, and an increase in the size of the apparatus. It was difficult to prevent.

Further, a method of diffusing and bonding a palladium foil to the surface of a porous carrier (Japanese Patent Laid-Open No. 7-51552).
For bonding a palladium-based foil through a metal layer alloyed with palladium or palladium (Japanese Patent Application Laid-Open No. 8-215551)
The formation of a film by this method has the effect of increasing the strength of the film and reducing the occurrence of pinholes. However, palladium is more expandable than gold, silver or copper. It is extremely difficult to process the foil into a thin film having a thickness of the order of a micron because of its low property. Furthermore, when gold or silver is used as a metal to be alloyed with palladium, the formation of such a thin film is generally dangerous using a poison such as potassium cyanide or sodium cyanide by an electroplating method. There is a problem with.

The present invention has been made in view of the difficulty in preventing pinholes from being generated in a conventional method for producing a palladium-based hydrogen separation membrane and the difficulty in processing a thin film in a method using a palladium-based foil. Yes, the yield of the palladium alloy membrane in the palladium-based hydrogen separation membrane is easily improved,
The object of the present invention is to provide a method for manufacturing a hydrogen separation membrane that can be manufactured at a low cost and high permeability by forming the hydrogen separation membrane as thin as possible.

[0009]

In order to solve the above problems, the gist of the present invention is to provide a method for manufacturing a hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas. In the method, (a) applying a metal foil alloying with palladium on the surface of the porous carrier;
(B) a hydrogen separation membrane comprising: a step of forming a palladium film on the surface of the metal foil; and (c) a step of forming a palladium alloy film mainly composed of palladium by heat treatment in a reducing atmosphere. It is a manufacturing method of. According to the above-described manufacturing method, a palladium alloy membrane can be easily formed without generating pinholes on the surface of the porous carrier, and a hydrogen separation membrane can be manufactured with high yield.
In addition, since no poison is used for depositing a metal alloying with palladium, the safety is high.

In a second aspect of the present invention, there is provided a method for producing a hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas, comprising the steps of (a) forming a palladium thin film on the surface of a porous carrier; (B) a step of depositing a metal foil that alloys with palladium on the surface of the palladium thin film; and (c) a step of forming a palladium alloy film mainly composed of palladium by heat treatment in a reducing atmosphere. A method for producing a hydrogen separation membrane, characterized in that: According to the above-described manufacturing method, a palladium alloy membrane can be easily formed without generating pinholes on the surface of the porous carrier, and a hydrogen separation membrane can be manufactured with high yield.
In addition, since no poison is used for depositing a metal alloying with palladium, the safety is high.

In the manufacturing method according to the first and second aspects, the metal foil to be alloyed with palladium may be a simple substance such as gold, silver or copper, an alloy thereof, or an alloy with another metal. It can be used, and as a method of forming a palladium film, a gas phase chemical reaction method, a vacuum deposition method,
A chemical plating method, an electroplating method, a method in which these methods are appropriately combined, or the like can be used. Further, the temperature for the heat treatment in the reducing atmosphere is 600 to 100.
The temperature is 0 ° C, preferably 700 to 900 ° C. When the temperature is lower than 600 ° C, alloying is not performed well. When the temperature is higher than 1000 ° C, the alloyed thin film may be scattered. In addition, as the porous carrier, a porous carrier formed of a material such as metal, ceramics, or glass into a cylindrical shape, a plate shape, or the like can be used. Furthermore, when a metal foil that is alloyed with palladium is applied, it is preferable to appropriately perform heat treatment at a suitable temperature in order to improve adhesion.

[0012]

Embodiments of the present invention will be described below. However, these embodiments are shown for explaining the present invention, and do not limit the scope of the present invention. One Embodiment of the Present Invention Step 1: A porous carrier molded into a cylindrical shape with ceramics is used as the porous carrier, and a silver foil having a predetermined thickness is obtained as a metal foil alloyed with palladium on the surface thereof. Winding and, if necessary, heat treatment at a temperature at which the silver foil does not melt in order to improve the adhesion to the porous carrier. Step 2: Electroless plating is performed for a predetermined time by immersion in a palladium electroless plating solution to form a palladium film on the surface of the silver foil. Step 3: A heat treatment is performed in a reducing atmosphere to form a palladium alloy film mainly containing palladium.

Further, another embodiment will be described. Step 1: As a porous carrier, a metal-made cylindrical carrier is used, and a palladium thin film is formed on its surface by electroplating. Step 2: A silver foil is wound on a surface of the palladium thin film as a metal foil to be alloyed with palladium so as to obtain a predetermined thickness, and if necessary, the silver foil is not melted in order to improve the adhesion with the porous carrier. Heat treatment at a temperature of Step 3: A heat treatment is performed in a reducing atmosphere to form a palladium alloy film mainly containing palladium.

In the above embodiment, before the heat treatment and the alloying treatment, a metal foil or a palladium film may be further added in order to adjust the overall film thickness or composition. Further, when using a metal as the porous carrier, it is preferable to form a palladium film by electroplating, but when using a nonconductive material such as ceramics or glass, it is preferable to use a chemical plating method. .

[0015]

Next, embodiments of the present invention will be described more specifically with reference to examples. (Example 1) A porous alumina tube was used as a carrier, and this carrier was used as a tin chloride solution (SnCl.H2O: 1 g + 37% HC).
1: 1 ml / L) and a palladium chloride solution (PdCl2:
0.1 g / 37% HCl: 0.1 ml / L) and then alternately and repeatedly immersed in the palladium plating solution [Pd (NH3) 4Cl2: 5.4 g + EDT] heated to 50 to 60 ° C.
A.2Na: 50.4 g + H2NNH2.H2O: 0.
35 ml / L] and stirred to form a palladium thin film (3 μm) on the surface of the carrier. Furthermore, it was immersed in an electroplating solution (Palladex 110 basic plating solution manufactured by Tanaka Kikinzoku Co., Ltd.) heated to about 60 ° C., and a thin layer of palladium (4.5 μm) was formed by electroplating. After that, silver foil (about 0.3μm) is put on the surface of the palladium thin film.
Was wound to a predetermined thickness (2.5 μm), and was heated at a temperature at which the silver foil would not melt in order to improve the adhesion to the porous carrier. Further, a heat treatment is performed while maintaining the temperature at 850 ° C. for 10 hours as a reducing atmosphere with hydrogen gas, and a thin film of silver and palladium is alloyed to form a palladium alloy film (palladium: 77 wt%, silver: 23 wt%, film thickness: 10 μm).
m) to produce a hydrogen separation membrane to which was applied. As a result, the leak amount when the pinhole was detected with the helium detector was 2.5 × 10 −5 Pa · m 3 / sec. The helium detector is a device for exploring a pinhole by reducing the pressure inside the object with a vacuum pump and spraying helium from the outside to measure the amount of leaked helium.

Example 2 A porous alumina tube was used as a carrier, and a silver foil (about 0.3 μm) was wound on the surface of the carrier to a predetermined thickness (2.5 μm), and then adhered to the porous tube. In order to improve the resiliency, heat treatment is performed at a temperature at which the silver foil does not melt, and furthermore, a reducing atmosphere using hydrogen gas is used to reduce
Heat treatment was carried out at 0 ° C. for 1 hour at that temperature. The carrier was immersed in an electroplating solution heated to about 60 ° C. (Palladex 110 basic plating solution manufactured by Tanaka Kikinzoku Co., Ltd.) to form a palladium thin film (7.5 μm) by electroplating. After that, a heat treatment is performed by maintaining the temperature at 850 ° C. for 10 hours as a reducing atmosphere with hydrogen gas,
A thin film of silver and palladium is alloyed to form a palladium alloy film (palladium: 77 wt%, silver: 23 wt%, film thickness 10
μm) was produced. as a result,
The leak amount when the pinhole was detected with the helium detector was 1.0 × 10 −5 Pa · m 3 / sec.

(Comparative Example 1) Using a porous alumina tube as a carrier, a thin film of palladium (7.5 μm) is formed on the surface of the carrier by electroless plating, and a thin film (2.5 μm) of electroplating is formed. After the formation, heat treatment is performed, and a thin film of silver and palladium is alloyed to form a palladium alloy film (palladium: 77 wt%, silver: 23 wt%, film thickness: 10 μm)
Was leaked when a pinhole was probed with a helium detector in a conventional hydrogen separation membrane having a hydrogen separation membrane to which the gas was adhered was 6.0 × 10 −5 Pa · m 3 / sec.

[0018]

Conventionally, even if an attempt is made to obtain a highly permeable palladium-based hydrogen separation membrane by making the palladium-based membrane as thin as possible, pinholes are likely to occur and the yield is poor, so that a palladium-based film having a thickness of about 20 μm is required. Although it was a hydrogen separation membrane formed with a membrane, according to the method of the present invention, even a palladium-based membrane of 10 μm or less can be manufactured with a high yield, and the price of the hydrogen separation membrane can be reduced and high permeability can be achieved. Can easily be produced.

Claims (2)

[Claims] 1. A method for producing a hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas, comprising: (a) applying a metal foil alloying with palladium to the surface of a porous carrier; A) a step of forming a palladium film on the surface of the metal foil; and (c) a step of forming a palladium alloy film mainly composed of palladium by heat treatment in a reducing atmosphere. Method. 2. A method for producing a hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas, comprising: (a) forming a palladium thin film on the surface of a porous carrier; and (b) forming the palladium thin film. A step of applying a metal foil that can be alloyed with palladium on the surface of the substrate, and (c) a step of forming a palladium-based palladium alloy film by heat treatment in a reducing atmosphere. Manufacturing method.