JP2001145825A - Method for manufacturing hydrogen separating membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hydrogen separating membrane by which a highly permeable hydrogen separating membrane can be easily manufactured at a price as low as possible. SOLUTION: In the method for manufacturing a Pd hydrogen separating membrane by which hydrogen is permeated and separated from a hydrogen- containing gas, a thin coating film of palladium or an alloy composed mainly of palladium is formed on the surface of a shape-forming base, which is, in turned, removed to manufacture the Pd hydrogen-separating membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a Pd-based hydrogen separation membrane for permeating and separating hydrogen from a hydrogen-containing gas.

[0002]

2. Description of the Related Art Hydrogen-containing gas is produced from natural gas, LPG, naphtha, kerosene, methanol or the like as a raw material by a steam reforming method or a partial oxidation method. Pure hydrogen is recovered from the contained gas and used for fuel cells, semiconductor production, metal refining, oil and fat production, petroleum refining, and the like.

Conventionally, methods for recovering pure hydrogen from the above-mentioned hydrogen-containing gas include a method of recovering pure hydrogen by separating and removing impurities other than hydrogen by a solution absorption method, an adsorption method or a cryogenic separation method. There is a membrane separation method in which hydrogen is permeated and separated by a membrane to recover pure hydrogen. Among them, the membrane separation method has attracted attention because of its energy saving, high separation efficiency, and simple device configuration.

Examples of the hydrogen separation membrane used in the membrane separation method include organic polymer membranes such as polyimide and polysulfone;
A film is used in which a porous ceramic film and a Pd-based film such as Pd or a Pd alloy are adhered to the surface of a porous carrier. Organic polymer membranes have problems such as heat resistance and reduced separation efficiency at high temperatures, and porous ceramics membranes have low separation efficiency. Further, a film in which a Pd-based film is adhered to the surface of a porous carrier is preferable because it has high strength and heat resistance and can obtain extremely high-purity hydrogen.

[0005] As a method for producing a Pd-based film supported by the porous carrier (hereinafter referred to as a carrier-coated Pd-based film), a Pd-based film is formed on the surface of the porous carrier by a gas phase chemical reaction method or vacuum deposition. Method (Japanese Patent Laid-Open No. 62-121)
No. 616), a chemical plating method in which the surface of a porous carrier is chemically activated and then applied by chemical plating (Japanese Patent Application Laid-Open No. 62-273030), and the surface of a metal porous carrier is electroplated. Electroplating method to be applied
Japanese Patent Application Laid-Open No. 5-139791), or a method in which a porous carrier is applied on the surface of a porous carrier by a chemical plating method and then further applied by an electroplating method (Japanese Patent Application Laid-Open No. Hei 5-137797).

[0006]

The carrier-adhered Pd-based films produced by the above-mentioned conventional methods all use porous glass, ceramics or metal as a carrier.
In order to prevent pinholes in the Pd-based film, it is necessary to strictly control the quality of the porous carrier, which complicates the operation and increases the price of the porous carrier. Therefore, there is a problem that the production cost of the carrier-adhered Pd-based film is also high. Further, the inhibition of the hydrogen permeability by the carrier cannot be ignored, and there is a problem that the separation efficiency is lowered. Further, in the case of a metal carrier, since the alloying treatment is performed in a high temperature range of 900 ° C. or higher, the diffusion of the carrier metal causes the hydrogen permeability of the Pd-based film to be extremely reduced. Some problems cannot be done.

The present invention has been made in view of the above-mentioned problems in the conventional method of manufacturing a Pd-based membrane, and has as its object to provide a method of manufacturing a hydrogen separation membrane which can easily manufacture a highly permeable hydrogen separation membrane at the lowest possible cost. It was done. In order to achieve this object, a Pd-based membrane that does not use a porous carrier has become the lowest-priced, highly permeable membrane, and how to produce the Pd-based membrane easily and reliably. The inventor of the present invention has invented a method for producing a hydrogen separation membrane by intensively studying the possibility.

[0008]

The gist of the present invention is to provide a method for manufacturing a Pd-based hydrogen separation membrane for permeating and separating hydrogen from a hydrogen-containing gas, according to the first aspect of the present invention. After forming a thin film of Pd or an alloy mainly composed of Pd, the shape-forming substrate is removed to remove Pd.
This is a method for producing a hydrogen separation membrane for producing a system hydrogen separation membrane.
According to the above-mentioned method, a low-priced P is used because no expensive carrier is used, and high permeability is obtained because no pinhole is generated.
A d-based film can be easily and reliably manufactured.

According to a second aspect of the present invention, in the manufacturing method of the first aspect, the shape-forming substrate has an outer diameter of 1 to 10 mm.
A method for producing a hydrogen separation membrane, characterized in that it is a heat-shrinkable thin tube. According to the above-described method, the shape-forming substrate can be easily removed, so that a Pd-based film with lower cost and higher permeability can be manufactured.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a hydrogen separation membrane produced by a production method according to an embodiment of the present invention. FIG. 1A is a cylindrical tubular hydrogen separation membrane, and FIG. The hydrogen separation membrane, (c) is a flat membrane-shaped hydrogen separation membrane having an enlarged surface area. FIG. 2 is a schematic longitudinal sectional view of a main part obtained by modularizing the cylindrical tubular hydrogen separation membrane shown in FIG.

In FIG. 1, 1a is Pd or Pd
A thin film of an alloy mainly composed of
A Pd-based hydrogen separation membrane (hereinafter simply referred to as a hydrogen separation membrane) in the form of a thin tube having a diameter of 10 to 10 mm; Numeral 1c denotes a flat membrane-shaped hydrogen separation membrane in which the flat membrane is formed in a bellows shape with a curve and the surface area is expanded. In addition,
The hydrogen separation membrane produced by the production method of the present invention is not limited to the above-described shape, and may have a large number of arc-shaped concave grooves formed on the side surface of the thin tube parallel to the longitudinal direction,
Further, in order to increase the surface area of the film, the film may have an appropriate uneven shape. Further, when the tubular membrane is modularized, both ends may be opened.

FIG. 2 shows a modularized tubular thin-film hydrogen separation membrane shown in FIG. 1 (a), wherein 1a is a thin-tube tubular hydrogen separation membrane whose one end is closed, and 2 is a wire mesh inserted into the tube. The hydrogen separation membrane is disposed because the hydrogen separation membrane is extremely thin and is easily damaged or broken. Reference numeral 3 denotes a tube sheet, which has perforations 5 through which a large number of tubular hydrogen separation membranes 1a are inserted at regular intervals, and the inserted tubular hydrogen separation membrane 1a is welded at a welding portion 4 on the open end side. Is done. The supporting member 2 is
It may be a nonwoven fabric or a spring formed of a thin metal wire. In addition, as a method of attaching the thin tubular hydrogen separation membrane 1a to the tube sheet 3, adhesion by an appropriate adhesive or attachment via a locking member may be used. Further, the module is disposed in a shell (not shown) in a shell and tube type. When disposed in a shell, it is also preferable to have a configuration in which both ends of the tubular hydrogen separation membrane 1a are opened and both ends are engaged with the tube sheet 3 in addition to the above configuration.

In order to separate hydrogen from a hydrogen-containing gas by the above-mentioned module, a hydrogen-containing gas is introduced into the tubular hydrogen separation membrane 1a from the open end side of the tubular hydrogen separation membrane 1a.
Since only hydrogen permeates the separation membrane 1a, it is recovered as pure hydrogen. In the above, a configuration may be adopted in which a hydrogen-containing gas is circulated outside the tubular hydrogen separation membrane 1a and pure hydrogen is recovered from the open end side.

Next, a method for producing the tubular hydrogen separation membrane 1a will be described in detail below. Heat-shrinkable materials such as plastics, metal materials that can be eluted by electrolysis such as aluminum, copper, and brass, incinerated materials such as carbon, wood, and paper;
Alternatively, a thin wire or a thin tube made of a low melting point metal or the like that melts at a low temperature is used as a shape forming base (hereinafter simply referred to as a base). When producing a film having a flat film shape or a shape having irregularities, it goes without saying that a substrate having a shape corresponding to those shapes is used.
It is preferable that the substrate has a tubular shape rather than a rod shape because of its higher heat shrinkage and higher combustion efficiency even when incinerated. Further, as the tubular substrate, an outer diameter 1 made of plastics such as heat-shrinkable fluororesin is used.
It is preferable to use a thin tube of 10 to 10 mm. When it is difficult to form a film by the method for forming a thin film described later, it is preferable to roughen the surface with a sound paper or the like.

A thin film of Pd or an alloy mainly composed of Pd is formed on the outer surface of the substrate by a method such as sputtering, electroless plating, electrolytic plating, CVD and ion plating, or a combination thereof. In order to form a thin film of an alloy mainly composed of Pd, a Pd film is formed thereon, and a Pd film and a 1B film of Cu, Ag, Au or the like are formed thereon.
At least one metal film is alternately formed among Group 8 metals such as Group, Co, Ni, Ru, Rh, Ir, and Pt or Group 3A metals such as Y, Ce, and Gd.

After a thin film such as a Pd film is formed on the outer surface of the base, the base is removed. In the case of a heat-shrinkable base, the base is contracted by appropriately heating to remove the base. It is possible to burn and remove in a non-shrinking substrate such as wood, and to remove in a metal such as aluminum and copper by eluting with an acid or electrolysis.
The low-melting-point metal substrate can be heated to a temperature equal to or higher than the melting point, melted and removed.

In order to manufacture a thin film of an alloy mainly composed of Pd, the substrate on which the metal film is laminated is removed by the above-mentioned method, and then heated to 900 ° C. or more in a vacuum or a reducing gas atmosphere and heat-treated. Can be alloyed by metal diffusion. The thickness of the hydrogen separation membrane produced by the above method,
It is preferably from 20 to 100 μm, and if it is less than 20 μm, it is difficult to remove the substrate, and the strength is too weak. On the other hand, when the thickness is 100 μm or more, the hydrogen permeation rate becomes too slow, which is not preferable.
The manufactured hydrogen separation membrane is modularized and used in a device for separating and recovering hydrogen from a hydrogen-containing gas or a membrane reactor.

[0018]

EXAMPLE A fluororesin tube having an outer diameter of 3 mm was used as a substrate, and the surface thereof was roughened with a sound paper. Then, an aqueous solution of stannous chloride (1 g / L) and an aqueous solution of palladium chloride (0.1 g) were used. / L) alternately to give a catalyst, and then 5.4 g of tetraamminepalladium dichloride.
/ L containing ammonia solution at pH 11 and electroless plating reduced by hydrazine on the surface of the substrate.
A Pd film of μm was formed. Using the formed Pd film as a cathode, a neutral palladium plating bath (25 g / Pd
L) and an aqueous solution of silver cyanide (24 g / L as Ag)
), And Pd films and Ag films were formed alternately. The film thickness after film formation was 40 μm, of which Ag was 23% by weight. After forming a film on the outer surface of the substrate, the fluororesin tube of the substrate was shrunk at a temperature of 150 ° C. and extracted. The film from which the substrate was removed was heat-treated under a nitrogen gas atmosphere at a temperature of 900 ° C. or more for 10 hours to be alloyed to produce a Pd—Ag hydrogen separation membrane. The prepared hydrogen separation membrane had no pinhole and was stable in shape and thickness.

[0019]

As described above, a thin-film hydrogen separation membrane can be produced without using a carrier, so that a low-cost, no pinhole is generated, and a highly permeable hydrogen separation membrane can be easily produced. Also,
Hydrogen separation membranes of various shapes can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a hydrogen separation membrane manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of a main part obtained by modularizing the cylindrical thin tubular hydrogen separation membrane of FIG. 1 (a).

[Description of Signs] 1a: Cylindrical tubular hydrogen separation membrane 1b: Expanded tubular hydrogen separation membrane 1c: Expanded flat membrane hydrogen separation membrane 2: Support member 3: Tube sheet 4: Welded part 5: Insertion hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA41 HA21 HA41 JA02A MA02 MA03 MC02X NA31 NA50 NA62 PB66 4G040 FA02 FB09 FC01 FE01

Claims (2)

[Claims] 1. Pd for permeating and separating hydrogen from a hydrogen-containing gas
In the method for producing a hydrogen separation membrane, a thin film of Pd or an alloy mainly composed of Pd is formed on the surface of the shape-forming substrate, and then the shape-forming substrate is removed to produce a Pd-based hydrogen separation membrane. Production method. 2. The method for producing a hydrogen separation membrane according to claim 1, wherein the shape-forming substrate is a heat-shrinkable thin tube having an outer diameter of 1 to 10 mm.