JP7263281B2 - Hydrogen permeable membrane - Google Patents

Description

Embodiments of the present invention relate to hydrogen permeable membranes.

Toward the realization of a hydrogen society with low carbon dioxide emissions, construction of a hydrogen energy system value chain for hydrogen production, transportation, storage, and utilization is under consideration.

Separation of the produced hydrogen differs in process depending on the purity of the hydrogen and the scale of the facility. Absorption methods and cryogenic separation methods are used to separate large amounts of hydrogen. In the case of medium-scale separation, the pressure swing adsorption method (PSA method), which yields high-purity hydrogen, is predominantly used. On the other hand, for example, in separation under a low-concentration environment, a membrane method with high operability and easy operation is used. And when performing high-temperature and ultra-high-purity refining, utilization of a hydrogen-permeable membrane is expected.

Various materials have been developed for hydrogen permeable membranes. For example, a hydrogen-permeable membrane formed using a palladium alloy has a high dissociation rate of hydrogen and easily permeates hydrogen atoms. On the other hand, non-palladium-based metals such as vanadium, niobium, and tantalum are known to have higher permeability coefficients and higher permeability than palladium. The permeation performance is believed to be derived from the crystal lattice of the metal, palladium being face-centered cubic (fcc) and the non-palladium-based metals being body-centered cubic (bcc). In face-centered cubic lattice metals, hydrogen enters at octahedral sites, and in body-centered cubic lattice metals, hydrogen enters at tetrahedral sites. It is believed that the short distance between the tetrahedral positions in the body-centered cubic lattice metal compared to the octahedral position, that is, the short diffusion distance, provides excellent hydrogen permeation performance.

JP 2015-58399 A JP-A-2004-174373 JP-A-2006-239528 JP-A-2008-75106 Patent No. 6056023 Patent No. 6014920 Patent No. 4917787

In order to efficiently obtain hydrogen of high purity, the above hydrogen-permeable membrane is required to further improve the hydrogen permeation performance.

Accordingly, the problem to be solved by the present invention is to provide a hydrogen-permeable membrane capable of enhancing hydrogen permeation performance, and a method for using the same.

The hydrogen-permeable membrane of the embodiment has a hydrogen-permeable metal layer, a dissociation portion, and a recombination portion, and selectively permeates hydrogen molecules contained in the source gas from the primary side to the secondary side. The hydrogen-permeable metal layer includes a first metal having a face-centered cubic lattice structure and a second metal having a body-centered cubic lattice structure. The dissociation section is provided on the primary side of the hydrogen-permeable metal layer, and dissociates hydrogen molecules contained in the source gas into hydrogen atoms. The recombination part is provided on the secondary side of the hydrogen-permeable metal layer, and recombines the hydrogen atoms dissociated in the dissociation part. In the hydrogen-permeable metal layer, the primary side contains more of the first metal than the second metal, and the secondary side contains more of the second metal than the first metal. The hydrogen-permeable metal layer is formed such that the composition is continuously graded from the first metal to the second metal from the primary side to the secondary side. It is used so that the primary side is at a higher temperature than the secondary side.

FIG. 1 is a cross-sectional view of a hydrogen-permeable membrane 1 according to the first embodiment. FIG. 2 is a diagram showing the relationship between temperature T and hydrogen permeability coefficient X for each metal material. FIG. 3 is a cross-sectional view of a hydrogen permeable film 1b according to the second embodiment. FIG. 4 shows the first metal having a face-centered cubic lattice (fcc) structure and the second metal having a body-centered cubic lattice (bcc) structure constituting the hydrogen-permeable metal layer 10 in the hydrogen permeable film 1b according to the second embodiment. It is a figure which shows a composition ratio.

<First embodiment>
[A] Structure of Hydrogen-Permeable Membrane 1 FIG. 1 is a cross-sectional view of a hydrogen-permeable membrane 1 according to the first embodiment.

In this embodiment, the hydrogen-permeable membrane 1 has a hydrogen-permeable metal layer 10, a dissociation section 20, and a recombination section 30, as shown in FIG. It is configured to selectively transmit to the side SS.

Specifically, hydrogen molecules contained in the raw material gas are dissociated into hydrogen atoms in the dissociation unit 20 in the primary side PS. The hydrogen atoms dissociated in the dissociation portion 20 dissolve and diffuse inside the hydrogen-permeable metal layer 10 . The hydrogen atoms diffused inside the hydrogen-permeable metal layer 10 recombine at the recombination portion 30 in the secondary side SS, return to hydrogen molecules, and are released.

Each part constituting the hydrogen permeable membrane 1 will be described in order.

[A-1] Hydrogen-permeable metal layer 10
The hydrogen-permeable metal layer 10 is a laminate of a first hydrogen-permeable metal layer portion 11 and a second hydrogen-permeable metal layer portion 12 .

The first hydrogen-permeable metal layer portion 11 is located on the primary side PS in the hydrogen-permeable metal layer 10 . The first hydrogen-permeable metal layer portion 11 is formed using a first metal having a face-centered cubic lattice structure. Examples of the first metal having a face-centered cubic lattice (fcc) structure include Ni, Pd, Pt, Ag, Pb, Al, Sr, Rh, Fe (γ), Ir, Au, Cu, Ca, or austenitic steel. is mentioned.

The second hydrogen-permeable metal layer portion 12 is located on the secondary side SS in the hydrogen-permeable metal layer 10 . Unlike the first hydrogen-permeable metal layer portion 11, the second hydrogen-permeable metal layer portion 12 is formed using a second metal having a body-centered cubic lattice structure. Examples of the second metal having a body-centered cubic lattice (bcc) structure include W, V, Ta, Na, Rb, Nb, Mo, Li, Fe(α), Cr, Ba, Cs, K, or martensite steel.

[A-2] Dissociation unit 20
The dissociation unit 20 is provided on the surface of the primary side PS in the hydrogen-permeable metal layer 10, and dissociates hydrogen molecules contained in the source gas into hydrogen atoms.

Although not shown, in the present embodiment, the surface of the primary side PS in the dissociation part 20 is formed with unevenness in order to promote the dissociation of hydrogen molecules.

[A-3] Recombining unit 30
The recombination part 30 is provided on the surface of the secondary side SS in the hydrogen-permeable metal layer 10, and hydrogen atoms diffused into the hydrogen-permeable metal layer 10 recombine.

Although not shown, in the present embodiment, unevenness is formed on the surface of the secondary side SS in the recombination portion 30 in order to promote the recombination of hydrogen atoms.

[B] Manufacturing Method An example of a manufacturing method for manufacturing the hydrogen permeable membrane 1 of the present embodiment will be described.

[B-1] Formation of Hydrogen-Permeable Metal Layer 10 When manufacturing the hydrogen-permeable membrane 1, first, the hydrogen-permeable metal layer 11 and the second hydrogen-permeable metal layer 12, which are laminates of the first hydrogen-permeable metal layer 11 and the second hydrogen-permeable metal layer 12, are formed. A metal layer 10 is formed.

Here, for example, the hydrogen-permeable metal layer 10 is formed by bonding the plate-like first hydrogen-permeable metal layer portion 11 and the plate-like second hydrogen-permeable metal layer portion 12 . Alternatively, the hydrogen-permeable metal layer 10 may be formed by laminating the first hydrogen-permeable metal layer 11 and the second hydrogen-permeable metal layer 12 by a film forming method such as sputtering. good.

The first hydrogen-permeable metal layer portion 11 and the second hydrogen-permeable metal layer portion 12 are provided, for example, so as to have thicknesses as shown below.
・Thickness of first hydrogen-permeable metal layer portion 11: 0.1 μm or more and 10 mm or less ・Thickness of second hydrogen-permeable metal layer portion 12: 0.1 μm or more and 10 mm or less

[B-2] Formation of Dissociated Portion 20 Next, the surface of the hydrogen-permeable metal layer 10 located on the primary side PS is subjected to surface treatment to form the dissociated portion 20 . That is, the surface of the first hydrogen-permeable metal layer portion 11 located on the primary side PS is subjected to surface treatment.

Here, for example, peening treatment is applied as the surface treatment. Examples of peening treatment include laser peening, shot peening, water jet, and air hammer. The specific surface area of the dissociated portion 20 is increased by forming minute unevenness on the surface of the hydrogen-permeable metal layer 10 located on the primary side PS by performing the peening process. For example, the surface of the dissociated portion 20 is processed so that the arithmetic mean roughness Ra is 0.1 μm or more and 10 μm or less depending on the thickness.

[B-3] Surface treatment of recombination part 30

Next, the surface of the hydrogen-permeable metal layer 10 located on the secondary side SS is subjected to surface treatment to form the recombination portion 30 . That is, the surface of the second hydrogen-permeable metal layer portion 12 located on the secondary side SS is subjected to surface treatment.

Here, as in the case of forming the dissociated portion 20, for example, peening treatment is performed as the surface treatment. The specific surface area of the recombination portion 30 is increased by forming minute unevenness on the surface of the hydrogen-permeable metal layer 10 located on the secondary side SS by performing the peening process. For example, the surface of the dissociated portion 20 is processed so that the arithmetic mean roughness Ra is 0.1 μm or more and 10 μm or less depending on the thickness.

[C] Method of use An example of a method of using the hydrogen-permeable membrane 1 of this embodiment will be described.

In the hydrogen-permeable membrane 1 of the present embodiment, when hydrogen contained in the raw material gas is selectively permeated from the primary side PS to the secondary side SS, the primary side PS of the hydrogen-permeable metal layer 10 is the secondary side SS. Keep the temperature higher than For example, when separating hydrogen mixed in a high-temperature reaction vessel or piping of a chemical plant, or a closed vessel in which heat is naturally generated, the hydrogen permeable membrane is arranged such that the primary side PS is positioned on the side of the vessel. 1 is used. Alternatively, the primary side PS may be heated. As a result, the hydrogen permeable membrane 1 of the present embodiment has a high hydrogen permeation performance, and hydrogen with high purity can be obtained efficiently.

The reason why the above effects are obtained will be described.

FIG. 2 is a diagram showing the relationship between temperature T and hydrogen permeability coefficient X for each metal material. FIG. 2 is prepared with reference to the contents described in the document "Buxbaum RE, Subramanian R, Park JH, Smith DL: Ind. Eng. Chem. Res., 530-537 (1996)".

As described above, in the hydrogen-permeable metal layer 10 of the present embodiment, the first hydrogen-permeable metal layer portion 11 provided on the primary side PS is made of the first metal having a face-centered cubic lattice (fcc) structure. Pd (palladium) and Ni (nickel), which are the first metals having a face-centered cubic lattice (fcc) structure, have a hydrogen permeability coefficient X that increases as the temperature T rises, and hydrogen becomes easier to pass through.

In contrast, in the hydrogen-permeable metal layer 10 of the present embodiment, the second hydrogen-permeable metal layer portion 12 provided on the secondary side SS is made of a second metal having a body-centered cubic lattice (bcc) structure. Nb (niobium), V (vanadium), and Ta (tantalum), which are the second metals of the body-centered cubic lattice (bcc) structure, hydrogen permeation decreases as the temperature T decreases, as shown in FIG. The coefficient X rises, making it easier for hydrogen to permeate.

Therefore, in the present embodiment, the temperature of the first hydrogen-permeable metal layer portion 11 made of the first metal having the face-centered cubic lattice (fcc) structure is set to 667K, for example. Then, the temperature of the second hydrogen permeable metal layer portion 12 made of the second metal having the body-centered cubic lattice (bcc) structure is set to 400K, for example. As a result, both the hydrogen permeation coefficient X of the first hydrogen-permeable metal layer portion 11 and the hydrogen permeation coefficient X of the second hydrogen-permeable metal layer portion 12 become high, as can be seen from FIG. Thus, by changing the temperature, the hydrogen permeation coefficient X can be adjusted and the hydrogen permeation performance can be enhanced.

Therefore, the hydrogen-permeable membrane 1 of the present embodiment has high hydrogen permeation performance, so that hydrogen with high purity can be obtained efficiently.

In addition, the second metal (Nb, V, Ta, etc.) having a body-centered cubic lattice (bcc) structure forming the second hydrogen-permeable metal layer portion 12 has low catalytic activity against hydrogen dissociation. However, in the present embodiment, the first hydrogen-permeable metal layer portion 11 made of a first metal (Pd, Ni, etc.) having a face-centered cubic lattice (fcc) structure is provided on the primary side PS of the second hydrogen-permeable metal layer portion 12. is provided. The first metal having a face-centered cubic (fcc) structure has a higher catalytic activity for hydrogen dissociation than the second metal having a body-centered cubic (bcc) structure. Therefore, in the hydrogen-permeable membrane 1 of the present embodiment, hydrogen dissociation is efficiently performed, so that hydrogen with high purity can be obtained efficiently.

In this embodiment, the surface of the dissociation section 20 located on the primary side PS and the surface of the recombination section 30 located on the secondary side SS are uneven. Therefore, in the present embodiment, the surface located on the primary side PS in the dissociation section 20 has a large specific surface area, so the dissociation into hydrogen atoms proceeds efficiently. In addition, since the surface located on the secondary side SS in the recombination portion 30 has a large specific surface area, recombination with hydrogen molecules proceeds efficiently.

[D] Modification A modification of the above embodiment will be described.

In the present embodiment, the case where the surface of the dissociation part 20 located on the primary side PS is uneven has been described, but the present invention is not limited to this. For example, it is preferable to attach a metal that promotes the dissociation of hydrogen molecules contained in the raw material gas into hydrogen atoms on the surface of the dissociation unit 20 located on the primary side PS. Specifically, metal particles such as Hf, Zr, Ti, Mn, Fe, Re, Ni, Co, Tc, Os, Ir, Ru, Pt, Rh, and Pd are adhered. Moreover, the above metals may be mixed by ion implantation. Thereby, it can be dissociated into hydrogen atoms more efficiently.

Moreover, it is preferable that the surface of the dissociation part 20 located on the primary side PS is configured to include a new metal surface. A new metal surface is formed, for example, by performing a chemical surface modification treatment. For example, by chemically dissolving the target metal with a special solution, fine unevenness can be formed on the surface and a new metal surface can be formed. Specifically, acid cleaning treatment, alkaline cleaning treatment, and neutral agent cleaning treatment can be mentioned. Commonly used acid cleaning treatments include hydrofluoric acid treatment, nitric acid treatment, hydrochloric acid treatment, sulfuric acid treatment, phosphoric acid treatment, and aqua regia treatment. Thereby, it can be dissociated into hydrogen atoms more efficiently.

The above surface modification treatments may be combined as appropriate according to the properties of the metal. For example, Pd, which is a hydrogen dissociation promoting metal, may be adhered to the surface treated with hydrofluoric acid. Further, Ni, which is a hydrogen dissociation accelerator, may be introduced by ion implantation into the laser peened surface.

<Second embodiment>
FIG. 3 is a cross-sectional view of a hydrogen permeable film 1b according to the second embodiment.

As shown in FIG. 3, the hydrogen-permeable film 1b of this embodiment differs from that of the first embodiment (see FIG. 1) in the structure of the hydrogen-permeable metal layer 10. As shown in FIG. Except for this point and related points, this embodiment is the same as the case of the first embodiment, and accordingly, descriptions of overlapping matters will be omitted as appropriate.

FIG. 4 shows the first metal having a face-centered cubic lattice (fcc) structure and the second metal having a body-centered cubic lattice (bcc) structure constituting the hydrogen-permeable metal layer 10 in the hydrogen permeable film 1b according to the second embodiment. It is a figure which shows a composition ratio. In FIG. 4, the vertical axis represents the composition ratio ([fcc]:[bcc]) between the first metal having a face-centered cubic lattice (fcc) structure and the second metal having a body-centered cubic lattice (bcc) structure, and the horizontal axis The axis indicates the position t in the thickness direction of the hydrogen-permeable metal layer 10 . On the horizontal axis, in the thickness direction of the hydrogen permeable metal layer 10, the position of the end of the primary side PS is indicated as "0" and the position of the end of the secondary side SS is indicated as "t1".

As shown in FIG. 4, the hydrogen-permeable metal layer 10 of this embodiment has a composition that is continuously graded from the first metal (fcc) to the second metal (bcc) from the primary side PS to the secondary side SS. It is formed to change as Here, the end of the primary side PS is entirely made of the first metal (fcc). Then, from the primary side PS to the secondary side SS, the proportion of the first metal (fcc) decreases and the proportion of the second metal (bcc) increases. The end of the secondary side SS is entirely made of the second metal (bcc).

The hydrogen-permeable metal layer 10 of the present embodiment is formed using, for example, a 3D printer (three-dimensional additive manufacturing apparatus) using a powder sintering additive manufacturing method.

In the present embodiment, as in the case of the first embodiment, in the hydrogen-permeable metal layer 10, the primary side PS contains the first metal (fcc) more than the second metal (bcc), and the secondary side SS is configured to contain more of the second metal (bcc) than the first metal (fcc). For this reason, in the present embodiment, as in the case of the first embodiment, the primary side PS of the hydrogen-permeable metal layer 10 is made to have a higher temperature than the secondary side SS, so that the hydrogen permeation performance is high. As a result, hydrogen with high purity can be obtained efficiently.

Unlike the first embodiment, the hydrogen-permeable metal layer 10 of this embodiment does not have a boundary between the layer of the first metal (fcc) and the layer of the second metal (bcc). Therefore, since there is no boundary barrier, the effect of increasing the mass transfer amount can be achieved.

The hydrogen-permeable metal layer 10 of the present embodiment is formed using, for example, nickel (Ni) as the first metal (fcc) and vanadium (V) as the second metal (bcc). Vanadium (V) is prone to hydrogen embrittlement. However, since the primary side PS, which reaches a high temperature, is formed so that the proportion of nickel (Ni) increases, it is possible to suppress the occurrence of hydrogen embrittlement.

<Others>
While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1: Hydrogen-permeable membrane 10: Hydrogen-permeable metal layer 11: First hydrogen-permeable metal layer portion 12: Second hydrogen-permeable metal layer portion 20: Dissociation portion 30: Recombination portion PS: Primary side SS :Secondary side

Claims (5)

A hydrogen permeable membrane through which hydrogen molecules contained in a raw material gas selectively permeate from the primary side to the secondary side,
a hydrogen-permeable metal layer containing a first metal having a face-centered cubic lattice structure and a second metal having a body-centered cubic lattice structure;
a dissociation unit provided on the primary side surface of the hydrogen-permeable metal layer for dissociating hydrogen molecules contained in the source gas into hydrogen atoms;
a recombination portion provided on the secondary side surface of the hydrogen-permeable metal layer, in which hydrogen atoms dissociated in the dissociation portion recombine,
In the hydrogen-permeable metal layer, the primary side contains more of the first metal than the second metal, and the secondary side contains more of the second metal than the first metal. is ,
the hydrogen-permeable metal layer is formed so that the composition changes continuously from the first metal to the second metal from the primary side toward the secondary side,
used such that the primary side is at a higher temperature than the secondary side;
Hydrogen permeable membrane. Concavities and convexities are formed on a surface of the dissociation portion located on the primary side and a surface of the recombination portion located on the secondary side,
The hydrogen permeable membrane according to claim 1 . A metal that promotes dissociation of hydrogen molecules contained in the raw material gas into hydrogen atoms is adhered to the surface of the dissociation unit located on the primary side.
The hydrogen permeable membrane according to claim 1 or 2 . The surface located on the primary side in the dissociation section includes a new metal surface,
The hydrogen permeable membrane according to any one of claims 1 to 3 . A method for using a hydrogen permeable membrane that selectively permeates hydrogen contained in a raw material gas from the primary side to the secondary side, comprising:
The hydrogen-permeable film has a hydrogen-permeable metal layer containing a first metal having a face-centered cubic lattice structure and a second metal having a body-centered cubic lattice structure,
In the hydrogen-permeable metal layer, the primary side contains more of the first metal than the second metal, and the secondary side contains more of the second metal than the first metal. has been
the hydrogen-permeable metal layer is formed such that the composition changes from the primary side to the secondary side with a continuous gradient from the first metal to the second metal;
In the hydrogen-permeable metal layer, the primary side is used so that the temperature is higher than the secondary side.
How to use the hydrogen permeable membrane.

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