JP5987197B2 - Hydrogen separation membrane and hydrogen separation method - Google Patents

Description

  The present invention relates to a hydrogen separation membrane, and more particularly to a hydrogen separation membrane without a Pd-based surface layer. The present invention also relates to a hydrogen separation method using this hydrogen separation membrane.

  Hydrogen separation membranes made of metal membranes are already used in industrial hydrogen purification, etc., and are expected to be applied to the separation of hydrogen contained in reformed gases and reaction gases such as city gas, petroleum, and coal. And development is ongoing. The permeation phenomenon of hydrogen into a hydrogen separation membrane made of metal is caused by the dissociation and solid solution of hydrogen on the surface of the introduction gas side, diffusion between the hydrogen separation membranes, recombination and desorption on the surface of the permeation side It goes through a separation process. For this reason, when hydrogen permeate | transmits selectively and there is no defect in a hydrogen permeable film, the hydrogen purity of the permeation | transmission side will be ultra high purity of 9N (99.999999999%) or more. Conventionally, it has been considered that Pd having catalytic activity is necessary in the surface process of hydrogen dissociation and recombination. When a Pd-based alloy is used as the separation membrane itself or when a non-Pd-based hydrogen separation membrane is used, Pd A surface thin film layer (coating metal film) has been considered necessary. This surface layer is usually formed very thin to about several hundred nm so as not to deteriorate the hydrogen permeation performance of the base metal layer.

  As a separation membrane prepared by coating a Pd surface layer on the surface of a base membrane made of a group 5A metal having a high hydrogen permeation performance and a low raw material cost compared to a Pd-based alloy, Patent Document 1 (Japanese Patent Laid-Open No. 11-276866) A hydrogen separation membrane is described in which a surface layer made of Pd or Pd alloy is provided on both sides of a metal base membrane (Nb, Ta, V or its alloy membrane) having high hydrogen permeation performance.

  Patent Document 2 (Japanese Patent Laid-Open No. 2008-272605) describes a hydrogen separation membrane in which a Pd or Pd alloy surface layer is provided on an amorphous alloy layer made of a Zr—Ni alloy or an Nb—Zr—Ni alloy. . However, since an amorphous alloy crystallizes at a high temperature, there is a problem that it cannot be used in a high temperature environment.

  Patent Document 3 (Japanese Patent Laid-Open No. 2006-239526) describes a hydrogen separation membrane having a Pd surface layer on at least one surface of a base membrane made of a group 5A metal.

JP-A-11-276866 JP 2008-272605 A JP 2006-239526 A

  In a non-Pd-based hydrogen separation membrane in which a Pd-based surface layer is provided on the surface of the base alloy layer, if hydrogen separation is continued at 400 to 600 ° C., the components of the base alloy layer and the Pd of the surface layer diffuse to each other. The hydrogen permeation performance of the membrane gradually decreases. Moreover, Pd is expensive.

  An object of this invention is to provide the hydrogen separation membrane which does not have the surface layer of Pd or Pd alloy, and the hydrogen separation method using this hydrogen separation membrane.

The hydrogen separation membrane of the present invention is a hydrogen separation membrane made of an alloy of V and Ru, wherein the Ru content in the alloy is 30 mol% or less, and a surface layer of Pd or Pd alloy is formed on the surface. It does not have.

  The hydrogen separation method of the present invention uses this hydrogen separation membrane.

In the hydrogen separation membrane of the present invention, since the Pd or Pd alloy surface layer is not provided on the surface of the group 5A metal membrane, the following effects are obtained.
(1) It is possible to reduce the production cost of the hydrogen separation membrane by reducing the amount of expensive Pd used and omitting the Pd surface layer deposition process.
(2) Since the mutual diffusion of the components of Pd and the base alloy layer does not occur, the hydrogen separation performance of the 5A group metal membrane having high hydrogen separation performance does not decrease, and the durability can be improved.
(3) Although it is necessary to reduce the thickness of the membrane in order to improve the hydrogen permeation performance, the processability is improved compared to a hydrogen separation membrane having a Pd-based surface layer, and the film is formed on a porous support that supports the membrane. Will also be easier.

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  Hereinafter, the present invention will be described in detail.

  The hydrogen separation membrane of the present invention is a hydrogen separation membrane made of Group 5A metal or an alloy thereof, and does not have a surface layer of Pd or Pd alloy on the surface.

  V, Nb, and Ta are suitable as the Group 5A metal, and the alloy may be any of Nb alloy, V alloy, Ta alloy, and the like. The alloy may be an alloy of 5A group metals, and W, Mo, Cr, Mn, Fe, Co, Ni, Ru, Rh, Pd, Re, Os, other than 5A group and other than 5A group. An alloy with at least one alloy element such as Ir, Pt, Ti, Zr, Hf, and Al may be used. The content of alloy elements other than Group 5A is preferably 30 mol% or less, particularly preferably 15 mol% or less.

  The group 5A metal or alloy film thereof can be produced by melting the group 5A metal or alloy thereof, and rolling it to a thickness of preferably 1 to 600 μm, particularly preferably 50 to 100 μm. In addition, you may employ | adopt means other than rolling for thin film formation. Further, the hydrogen separation membrane of the present invention may be formed on the surface of the air-permeable support material by a film forming method such as sputtering, CVD, or plating to have a thickness of 1 to 100 μm, particularly about 1 to 20 μm. .

  The hydrogen separation membrane of the present invention is not provided with a surface layer of Pd or a Pd-based alloy on the surface.

  As a hydrogen separation apparatus provided with the hydrogen separation membrane of the present invention, a hydrogen separation membrane is installed in a container called a housing, a casing, a vessel or the like, and a primary chamber and a secondary chamber separated by a hydrogen separation membrane, The structure is not particularly limited as long as it has a heating means as necessary. The form of the film may be any form such as a flat film type and a cylindrical type. The hydrogen separation membrane may be superimposed on a porous support or a support plate having a groove on the surface, or may be formed on the surface of the porous body. As a porous body, any of a metal material, a ceramic material, etc. may be sufficient.

  In the present invention, hydrogen gas of about 2N (99%) to 7N (99.99999%) is permeabilized to produce ultra-high purity hydrogen gas of more than 7N, particularly 9N (99.9999999%) or more. Is preferred. Such ultra-high purity hydrogen gas is suitable for use in semiconductor manufacturing processes and the like. However, the present invention is not limited to this, and can be used for the purpose of separating hydrogen from various hydrogen-containing gases.

  The operating temperature (specifically, the gas temperature on the primary side) of the hydrogen separator is usually about 300 to 700 ° C., particularly about 400 to 600 ° C., although it depends on the composition of the membrane.

  When organic substances are attached to the surface of the hydrogen separation membrane, air is introduced into the hydrogen separator after starting the operation of the hydrogen separator and after supplying the hydrogen gas after the temperature of the hydrogen separator is increased. Then, organic substances adhering to the film surface may be removed by oxidation.

  Hereinafter, examples and comparative examples will be described.

[Example 1]
Pure V was rolled to produce a hydrogen separation membrane having a thickness of 96 μm and a diameter of 12 mm. This hydrogen separation membrane was set in the test module 1 shown in FIG. 13, and the hydrogen permeation rate was measured.

  In this hydrogen permeation test module 1, a hydrogen separation membrane 4 is disposed between a rear end face of a gas introduction pipe 2 and a front end face of a gas extraction pipe 6 via gaskets 3 and 5. A nut 7 is fitted on the introduction pipe 2, and a cap nut 8 is engaged with a flange portion 6 a at the tip of the extraction pipe 6.

  The cap nut 8 is extended to the introduction tube 2 side, and a male screw on the outer peripheral surface of the nut 7 is screwed into a female screw on the inner peripheral surface. The leading end of the nut 7 comes into contact with the flange portion 2 a at the rear end of the introduction pipe 2, whereby the extraction pipe 6 is attracted to the introduction pipe 2 side through the cap nut 8, and the rear end surface of the introduction pipe 2 and the extraction pipe 6 are The hydrogen separation membrane 4 is sandwiched between the front end surface via the gaskets 3 and 5.

  The gaskets 3 and 5 have an annular shape of the same size, and the area of the inner hole is the membrane permeation area A of the hydrogen separation membrane 4. The cap nut 8 is provided with a small hole 8a for a gas leak test.

Although the inner hole of the gasket is 5.6 mm, the diameter of the contact portion between the gasket and the membrane sample when tightened with a VCR is 7.1 mm, and the effective membrane permeation area A is 39.6 mm ² (3.96). × 10 ⁻⁵ m ² ).

  The hydrogen permeation test module 1 is installed in an electric furnace, the raw material gas is supplied to the introduction pipe 2, and the hydrogen gas is taken out from the extraction pipe 6.

The V film was heated to 550 ° C. under vacuum. At a temperature of 550 ° C., a process side pressure (Inlet pressure) of 400 kPa, a hydrogen permeation side pressure (Outlet pressure) of 200 kPa, the flow rate of hydrogen permeating to the hydrogen permeation side (hydrogen permeation rate) is measured, and based on the measurement, mol / m · s · Pa ^1/2 ) was calculated. As a result, as shown in FIG. 1, it was confirmed that even with the V film without the Pd surface thin film layer, high hydrogen permeation performance was maintained for 8 hours without deterioration of hydrogen permeation performance.

[Examples 2 to 12]
Example 2: V-5W, 488 μm
Example 3: Nb-5W, 507 μm
Example 4: V-4Cr, 571 μm
Example 5: V-8Cr, 380 μm
Example 6: V-5Mo, 363 μm
Example 7: V-10Mo, 582 μm
Example 8: V-5Ru, 588 μm
Example 9: V-9.2Al, 371 μm
Example 10: V-5Co, 459 μm
Example 11: V-15W-5Mo, 498 μm
Example 12: V-5W-15Mo, 528 μm
A hydrogen separation membrane was produced in the same manner as in Example 1 except that the hydrogen permeation rate was measured in the same manner as in Example 1, and the hydrogen permeation coefficient was calculated based on the hydrogen permeation rate. The results are shown in FIGS. Indicated. The process side pressure (Inlet), the hydrogen permeation side pressure (Outlet), and the test temperature in each example were as described in FIGS. V-5W represents a V alloy containing 5 mol% of W, and Nb-5W represents an Nb alloy containing 5 mol% of W. V-4Cr and V-8Cr represent V alloys containing 4 mol% and 8 mol% of Cr, V-5Mo and V-10Mo represent V alloys containing 5 mol% and 10 mol% of Mo, respectively. 5Ru represents a V alloy containing 5 mol% of Ru, V-9.2Al represents a V alloy containing 9.2 mol% of Al, V-5Co represents a V alloy containing 5 mol% of Co, and V-15W. -5Mo represents a V alloy containing 15 mol% W and 5 mol% Mo, and V-5W-15Mo represents a V alloy containing 5 mol% W and 15 mol% Mo.

[Discussion]
The hydrogen separation membranes of Examples 1 to 12 have a high hydrogen permeation rate even without the Pd surface layer. All hydrogen separation membranes have stable hydrogen permeation performance over 8 hours, and in particular, V alloy membranes in which W of Examples 2, 3, 11, and 12 is alloyed metal, and V-Mo alloys of Example 7 The film and the V-Al alloy film of Example 9 were found to allow hydrogen permeation for 20 hours without degradation of hydrogen permeation performance. Further, as shown in FIG. 3, it was confirmed that the Nb-5W alloy film permeates hydrogen without deterioration in hydrogen permeation performance for about 3 days. 1 to 12 show the hydrogen permeation coefficients of the pure Pd film and the Pd-25Ag film, but the films of Examples 1 to 12 all have a larger hydrogen permeation coefficient.

DESCRIPTION OF SYMBOLS 1 Hydrogen permeation test module 2 Gas introduction pipe 3, 5 Gasket 4 Hydrogen separation membrane 6 Gas extraction pipe 7 Nut 8 Cap nut

Claims (4)

A hydrogen separation membrane made of an alloy of V and Ru, wherein the Ru content in the alloy is 30 mol% or less and does not have a surface layer of Pd or Pd alloy on the surface.   The hydrogen separation membrane according to claim 1, wherein the thickness is 1 to 600 μm.   A hydrogen separation method in which a hydrogen-containing source gas is supplied to one side of the hydrogen separation membrane according to claim 1 or 2 and purified hydrogen gas is taken out from the other side.   The hydrogen separation method according to claim 3, wherein the hydrogen-containing raw material has a hydrogen purity of 2N to 7N and the purified hydrogen gas has a purity of more than 7N.

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