JP2014184381A - Hydrogen separation body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen separation body in which a gas leakage can be reduced.SOLUTION: A hydrogen separation body (1) comprises: a ceramic porous support (5) through which a gas can pass; a ceramic dense layer (11) having an airtightness which is formed on a part of a surface of the porous support (5); a ceramic porous layer (13) which covers an area, which is not covered by the dense layer (11), of the surface of the porous layer (5) and a part of the dense layer (11) and through which the gas can pass; and a hydrogen separation layer (15) which has a hydrogen separation metal which can selectively transmit only hydrogen from gaseous matter containing hydrogen, covers the porous layer (13) and of which an end is jointed to the dense layer (11). Further, the hydrogen separation layer (15) is a mixed layer containing a ceramic and the hydrogen separation metal, the interface of the end contacting the dense layer (11) is configured from a ceramic porous base (19) and the hydrogen separation metal filled in a pore (21) of the porous base (19).

Description

  The present invention relates to a hydrogen separator capable of obtaining high-purity hydrogen gas by selecting and separating hydrogen gas from a gas to be separated (source gas) such as a hydrogen-containing gas.

  Conventionally, for example, in order to produce hydrogen to be supplied to a fuel cell, a hydrogen separator that selectively extracts only hydrogen from a gas containing hydrogen such as steam reformed gas has been developed. This hydrogen separator is, for example, hydrogen made of a hydrogen permeable metal (hereinafter referred to as a hydrogen separation metal) that allows only hydrogen such as palladium (Pd) or Pd alloy to permeate on the surface of a bottomed cylindrical ceramic porous body. A permeable membrane (hereinafter referred to as a hydrogen separation layer) is formed.

  A metal member such as a metal joint is attached to the open end (base end side) of this type of hydrogen separator, and is accommodated in a metal container such as stainless steel via the metal member. That is, a metal member is attached to the hydrogen separator, and the hydrogen separator is fixed to the metal container by the metal member to constitute a hydrogen separation module.

  In recent years, as the hydrogen separator described above, as shown in FIG. 11, a ceramic-made dense layer P2 having airtightness is provided on the surface of a ceramic-made porous support P1, and the porous support is provided. A porous layer P3 made of ceramics is formed at a location where the dense layer P2 of P1 is not formed (partly overlapping the dense layer P2), and further plated so as to cover the porous layer P3. Discloses a hydrogen separation membrane P4 that is a metal membrane made of a hydrogen separation metal (see Patent Document 1).

JP 2007-269600 A

  However, in the above-described conventional technology, the dense layer P2 and the hydrogen separation membrane P4 are joined at the interface where the dense layer P2 and the hydrogen separation membrane P4 made of different materials are in direct contact with each other. There is a problem that it is difficult to say that it is effective for repeated operations such as start and stop.

  That is, the dense layer P2 made of ceramics and the hydrogen separation membrane P4 which is a metal layer (of Pd or Pd alloy) are greatly different in thermal expansion coefficient, and the dense layer P2 and the hydrogen separation membrane P4 are at the interface. Since the bonding state is simply in close contact, the bonding property between the dense layer P2 and the hydrogen separation membrane P4 is reduced while the hydrogen separator is repeatedly used (with a change in temperature). There was something to do. As a result, there is a problem in that the gas tightness is lowered and gas leakage occurs between the dense layer P2 and the hydrogen separation membrane P4.

  In addition, the thickness of the porous layer P3 formed on the dense layer P2 and the width in which the dense layer P2 and the porous layer P3 overlap in the axial direction are limited. For example, when the thickness of the porous layer P3 formed on the dense layer P2 is 5 μm or more, the adhesion between the porous layer P3 and the hydrogen separation membrane P4 is deteriorated. Further, when the width in which the porous layer P3 and the dense layer P2 overlap in the axial direction becomes 5 mm or more, the porous layer P3 formed on the dense layer P2 is formed when the hydrogen separation membrane P4 is formed by plating or the like. The permeability of the liquid into the pores is poor, and it becomes difficult to form a film without defects.

And, when the gas leaks from the interface in this way, the purity of the separated hydrogen is lowered, so that improvement has been demanded.
The present invention has been made to solve the above-described problems, and an object thereof is to provide a hydrogen separator that can reduce gas leakage in the hydrogen separator.

  (1) The present invention provides, as a first aspect, a ceramic porous support capable of passing gas, and a ceramic dense layer formed on a part of the surface of the porous support and having airtightness. A porous layer made of ceramic that covers a region of the surface of the porous support that is not covered with the dense layer and a part of the dense layer, and that allows the gas to pass therethrough, and hydrogen. In a hydrogen separator comprising a hydrogen separation metal that selectively permeates hydrogen from a gas, covers the porous layer, and has a hydrogen separation layer whose end is joined to the dense layer. The hydrogen separation layer is a mixed layer containing a ceramic and the hydrogen separation metal, and the interface between the end portions in contact with the dense layer is formed between the porous substrate made of the ceramic and the pores of the porous substrate. Filled with said hydrogen separating metal, And wherein the Rukoto.

  In the first aspect, the hydrogen separation layer is a mixed layer containing a ceramic and a hydrogen separation metal, and the end interface in contact with the dense layer (the end surface portion constituting the interface on the hydrogen separation layer side) is ceramic. And a hydrogen separation metal filled in pores of the porous substrate.

  That is, the interface on the hydrogen separation layer side is a dense structure in which the pores of the porous substrate are filled with the hydrogen separation metal, so the dense layer and the hydrogen separation layer are firmly bonded without any gaps. There is a remarkable effect that gas leakage at the interface can be reduced. Thereby, the purity of hydrogen to be separated can be increased (for example, to 99.99% or more).

  In particular, when hydrogen is separated from the raw material gas, since a differential pressure is provided between the outer side and the inner side of the hydrogen separator (so that the pressure on the raw material gas side becomes higher), gas leakage is likely to occur. By using the hydrogen separator of the aspect, gas leak can be suitably prevented.

  (2) In the present invention, as a second aspect, the hydrogen separation layer is composed entirely of a porous substrate made of the ceramic and the hydrogen separation metal filled in the pores of the porous substrate. It is characterized by being.

In the second embodiment, the entire hydrogen separation layer (not only the interface) has a structure in which the pores of the porous substrate are filled with the hydrogen separation metal.
Therefore, the hydrogen separation layer can prevent only the gas other than hydrogen from passing therethrough and allow only hydrogen to pass therethrough.

  (3) In the third aspect of the present invention, the third aspect covers the surface of the hydrogen separation layer and has a structure in which an end portion of the hydrogen separation layer is joined to the dense layer so that the hydrogen can pass therethrough. It is characterized by having a protective layer for protecting.

  In the third aspect, since a protective layer (for example, a porous protective layer) is provided on the surface of the hydrogen separation layer, the poisoning substance (for example, iron in the storage container) is a hydrogen separation layer (specifically, a hydrogen separation metal). It is possible to prevent the hydrogen purity from being reduced by adhering to and reacting with.

  (4) As a fourth aspect of the present invention, an airtight seal layer is disposed in close contact with the surface of the dense layer at a position away from the hydrogen separation layer, and the seal layer is sandwiched between the seal layers. Thus, the metal members are arranged in close contact with each other.

  In the fourth aspect, the seal layer is disposed so as not to contact the hydrogen separation layer (specifically, the hydrogen separation metal). Therefore, various materials that react with the hydrogen separation metal can be used as the material of the seal layer.

In addition, when manufacturing the hydrogen separator of each claim mentioned above, the following manufacturing method is employable.
A first step of forming a dense layer on the porous support, a second step of forming a porous layer on a porous support on which a part of the dense layer and the dense layer are not formed, and the dense layer A third step of forming a porous first layer so as to cover the surface of a part of the porous layer and the porous layer; and a fourth step of attaching a material serving as a nucleus in plating to the first layer; A fifth step of forming a porous second layer on the first layer to which the nucleus is attached to form a laminated portion, and plating the laminated portion to form pores in the first layer. And a sixth step of generating and filling the hydrogen separation metal with a method for producing a hydrogen separator.

It is sectional drawing which fractures | ruptures and shows the hydrogen separator of Example 1 along an axial direction. It is explanatory drawing which fractures | ruptures the hydrogen separator of Example 1 along an axial direction, expands the part (A part of FIG. 1), and shows typically. It is explanatory drawing which fractures | ruptures the hydrogen separator of Example 1 along an axial direction, and further expands the part (B section of FIG. 2) further, and shows typically. It is sectional drawing which fractures | ruptures and shows the hydrogen separator in Example 1 along an axial direction. It is explanatory drawing which fractures | ruptures the hydrogen separation apparatus in Example 1 along an axial direction, and expands the base end side of a hydrogen separator further, and shows typically. It is explanatory drawing which shows the manufacture procedure etc. of a ceramic sintered compact among the manufacturing methods of the hydrogen separator of Example 1. FIG. It is explanatory drawing which shows the manufacturing procedure etc. of a porous layer among the manufacturing methods of the hydrogen separator of Example 1. FIG. It is explanatory drawing which shows the electroplating of an internal electric power feeding system among the manufacturing methods of the hydrogen separator of Example 1. FIG. It is explanatory drawing which fractures | ruptures the hydrogen separator in a comparative example along an axial direction, and expands the base end side of a hydrogen separator further, and shows typically. (A) is an explanatory view schematically showing the hydrogen separator in Modification 1 along the axial direction, and (b) is an illustration schematically showing the hydrogen separator in Modification 2 along the axial direction. It is explanatory drawing shown. It is explanatory drawing of a prior art.

Hereinafter, embodiments of the present invention will be described.
-As a material of a porous support body, ceramics are used, for example. Examples of the ceramic include at least one of yttria stabilized zirconia, stabilized zirconia, alumina, magnesia, ceria, and doped ceria.

  -The dense layer has airtightness. Here, examples of the airtightness include airtightness without gas permeation, but it is sufficient that at least the permeation of the raw material gas from which hydrogen is separated can be prevented, for example, a denseness with a relative density of 70% or more.

  As the material of this dense layer, for example, ceramics are used. As this ceramic, at least one of yttria-stabilized zirconia, stabilized zirconia, alumina, magnesia, ceria, and doped ceria can be used in the same manner as the support.

-As a material which comprises a hydrogen separation layer, a porous base | substrate and a hydrogen separation metal are mentioned.
Among these, as the material of the porous substrate, for example, ceramics is used. Examples of the ceramic include at least one of yttria stabilized zirconia, stabilized zirconia, alumina, magnesia, ceria, and doped ceria.

  On the other hand, examples of the hydrogen separation metal include Pd, PdCu alloy, PdAg alloy, and PdAu alloy. Specifically, Pd, Cu, Ag, Au, PdCu alloy, PdAg alloy, and PdAu alloy can be used. Cu, Ag, and Au are not used alone, but are alloys for use in alloying with Pd having hydrogen permeability.

  -As a pore of a porous substrate, the range whose average pore diameter is 100 nm-1 micrometer is employable, for example. Further, when the degree of filling of the hydrogen separation metal in the pores ((volume of hydrogen separation metal in the pores / volume of the pores) × 100) is 95% by volume or more, the permeation of gases other than hydrogen is prevented. However, it is preferable because only hydrogen can permeate.

  -As the protective layer, a porous ceramic layer capable of permeating raw material gas and hydrogen gas can be cited. The material of this ceramic layer is yttria stabilized zirconia, stabilized zirconia, alumina, magnesia, ceria, doped ceria. Among them, at least one is mentioned.

-As a material of a metal member, stainless steel is mentioned.
Examples of the present invention will be described below.

Here, an example of a hydrogen separator that selectively separates hydrogen from a source gas will be described.
a) First, the configuration of the hydrogen separator of this example will be described.

  As shown in FIG. 1, the hydrogen separator 1 of this embodiment is a test tube-shaped member that selectively separates hydrogen from a raw material gas (for example, a reformed gas produced by bringing natural gas and water vapor into contact with a catalyst). The distal end side (upper side in the figure) is closed, the proximal end side (lower side in the figure) is opened, and the center hole 3 is provided at the axial center.

  The hydrogen separator 1 includes a test tube-shaped porous support 5 as a basic configuration, and a layered surface structure 7 described later is provided on the outer surface of the porous support 5. . The dimensions of the hydrogen separator 1 are, for example, length 300 mm × inner diameter 6 mm × outer diameter 10 mm.

  Of these, the porous support 5 is made of yttria-stabilized zirconia (YSZ), and is a support made of porous ceramics having air permeability. The porosity of the porous support 5 is, for example, 40%, and has a structure that can transmit the source gas.

  On the other hand, the surface structure 7 includes a dense layer 11, a porous layer 13, a hydrogen separation layer 15, and a protective layer 17, as shown in FIG. I have. Each configuration will be described below.

  The dense layer 11 is in close contact with the porous support 5 on the open end side (base end side: left side in FIG. 2) of the porous support 5 and covers the outer surface (outer periphery side: upper side in FIG. 2). Thus, it is formed in a cylindrical shape. The dense layer 11 has a thickness of, for example, 20 μm, and a width (length in the axial direction: the length in the left-right direction in FIG. 2) is, for example, 20 mm.

The dense layer 11 is made of YSZ and has no air permeability (that is, has air tightness).
The porous layer 13 is made of porous ceramic and is in close contact with the exposed portion so as to cover the entire exposed portion of the outer peripheral surface of the porous support 5 (that is, the portion not covered with the dense layer 11). Is formed. Further, the base end side of the porous layer 13 is joined to the outer peripheral surface of the dense layer 11 on the front end side (right side in FIG. 2) and covers a part of the outer peripheral surface. That is, the entire periphery of the dense layer 11 is covered with the porous layer 13 so that the distal end side of the dense layer 11 is not exposed to the outside.

The porous layer 13 is made of YSZ and is a porous ceramic coating layer having a gas permeability. The porosity of the porous layer 13 is, for example, 50%, and has a structure capable of transmitting a raw material gas.
The hydrogen separation layer 15 is formed in close contact with the porous layer 13 so as to cover the entire outer surface of the porous layer 13. Further, the base end side of the hydrogen separation layer 15 is formed so as to be in close contact with the outer peripheral surface on the tip end side of the dense layer 11.

  As shown in an enlarged view of FIG. 3 (part B in FIG. 2), the hydrogen separation layer 15 is formed of a hydrogen permeable metal (in this embodiment, a PdAg alloy) in the pores 21 of the porous substrate 19 made of YSZ. ) Which is filled with a hydrogen separation metal. This hydrogen separation metal is a metal that separates hydrogen from the source gas by selecting and allowing only hydrogen from the source gas to permeate.

  That is, the hydrogen separation layer 15 is a mixed layer containing a ceramic and a hydrogen separation metal, and is composed of a porous substrate 19 made of ceramic and a hydrogen separation metal filled in the pores 21.

  Therefore, at the portion (interface) where the hydrogen separation layer 15 and the dense layer 11 are in contact with each other, the end including the interface on the hydrogen separation layer 15 side is the hydrogen separation metal filled in the porous substrate 19 and its pores 21. (That is, composed only of the porous substrate 19 and the hydrogen separation metal). In addition, the ratio with which the hydrogen separation metal is filled in the pores 21 is, for example, 95% by volume or more.

Hereinafter, a portion made of a hydrogen separation metal filled in the pores 21 of the hydrogen separation layer 15 is referred to as a hydrogen separation metal portion 16.
In addition, as shown in FIG. 2, the range (width: axial length) A1 in which the porous layer 13 and the dense layer 11 overlap is, for example, 1 to 5 mm. In addition, the thickness (radial length) A2 of the parallel region between the dense layer 11 and the hydrogen separation layer 15 is, for example, 0.1 to 10 μm. Furthermore, the width A3 (length in the axial direction) at which the hydrogen separation layer 15 is in contact with the dense layer 11 is about 1 to 10 μm. Since these dimensions A1 to A3 are slightly different depending on the positions in the circumferential direction, the average values are shown. In addition, the dimension of A1-A3 is not limited above, It is the structure where the dense layer 11 and the hydrogen separation layer 15 adhered firmly, and has high airtightness.

  The protective layer 17 is made of a porous ceramic and is formed in close contact with the hydrogen separation layer 15 so as to cover the entire outer surface of the hydrogen separation layer 15. That is, the protective layer 17 is integrated with the surface of the hydrogen separation layer 15 and covers the surface. Further, the proximal end side of the protective layer 17 is formed so as to be in close contact with and bonded to the outer peripheral surface on the distal end side of the dense layer 11.

  Since this protective layer 17 is a porous coating layer made of YSZ and spreads outside the hydrogen separation layer 15, contaminants (for example, Fe) that damage the hydrogen separation layer 15 from the outside are removed from the hydrogen separation layer. 15 is prevented.

b) Next, a hydrogen separator equipped with the hydrogen separator 1 will be briefly described.
As this hydrogen separator, for example, an apparatus described in JP 2012-7727 A can be employed.

  Specifically, as shown in FIG. 4, the hydrogen separator 31 includes a hydrogen separator 1, a cylindrical mounting bracket 33 into which the open end side of the hydrogen separator 1 is inserted, and an outer peripheral surface of the hydrogen separator 1. And a cylindrical sealing layer 35 (for performing gas sealing) disposed between the inner peripheral surface of the mounting bracket 33 and a cylindrical sealing member that is fitted on the hydrogen separator 1 and presses the distal end side of the sealing layer 35. A pressing metal fitting 37 and a cylindrical fixing metal fitting 39 that is externally fitted to the pressing metal fitting 37 and screwed into the mounting metal fitting 33 are provided. In FIG. 4, the surface structure 7 is omitted.

  The mounting bracket 33 includes a distal end side tubular portion 41, a flange portion 43, and the like, and a through hole (hollow portion) 45 serving as a gas flow path is formed at the center of the shaft. The base end side end of the hydrogen separator 1 is accommodated. The fixing bracket 39 includes a pressing plate 47 and a cylindrical portion 49. The pressing metal 37 is disposed adjacent to the seal layer 35 in the space 50 between the mounting metal 33 and the hydrogen separator 1.

  The seal layer 35 includes a first seal member 35a and a second seal member 35b made of ring-shaped expanded graphite, and a third seal member 35c made of ring-shaped glass disposed between the seal members 35a and 35b. Consists of.

Specifically, the first and second seal members 35a and 35b are heat-resistant gaskets made of expanded graphite, and the thermal expansion coefficient of the expanded graphite is approximately 1 to 25 × 10 ⁻⁶ / ° C. Since the first and second seal members 35a and 35b are arranged in a compressed state by the pressing fitting 37, the leakage of the raw material gas in the space 50 is prevented.

The third seal member 35c is made of, for example, borosilicate glass (B ₂ O ₃ —SiO ₂ —R ₂ O), has a softening point of 570 ° C., and has a thermal expansion coefficient of 10.4 × 10 ^{−. 6} / ° C. This glass ring is softened by the environment of the temperature at which the hydrogen separator 31 is used, for example, 600 ° C. and is closely adhered to the surroundings, and the first and second seal members 35a and 35b and the outer peripheral surface of the hydrogen separator 1 A gas seal is provided between the mounting bracket 33 (specifically, the distal end side tubular portion 41) and the inner peripheral surface thereof.

  Here, the metal fitting 51 is constituted by the mounting fitting 33, the pressing fitting 37, and the fixing fitting 39, and the hydrogen separator 1 (and hence the hydrogen separator 31) is made of a stainless metal container 53 by the metal fitting 51. It is fixed and accommodated. The hydrogen separation module 55 is configured by the hydrogen separation device 31 housed in the metal container 53.

  Further, in this embodiment, as shown schematically in an enlarged view of the main part in FIG. 5, the seal layer 35 composed of the first to third seal members 35 a to 35 c is disposed on the surface of the dense layer 11. The hydrogen separation layer 15 and the protective layer 17 are arranged separately so as not to come into contact with each other.

  That is, the sealing layer 35 is formed on the surface of the dense layer 11 in a direction perpendicular to the stacking direction in which the layers 11, 13, 15, and 17 are stacked (the left-right direction in the figure). 17 is arranged apart from the above.

  As shown in FIG. 4, in the hydrogen separation module 55 described above, for example, when the source gas is supplied to the outside of the hydrogen separator 1 (therefore, inside the metal container 53), the hydrogen separator 1 generates the source gas from the source gas. The hydrogen is separated and taken out to the outside through the central hole 3 of the hydrogen separator 1.

  On the other hand, when the source gas is supplied to the center hole 3 of the hydrogen separator 1, the hydrogen gas is separated from the source gas by the hydrogen separator 1, and the hydrogen is outside the hydrogen separator 1 ( Therefore, it is discharged into the metal container 53).

Examples of the source gas include a mixed gas of a hydrocarbon gas such as methane and water vapor, or a mixed gas containing at least hydrogen gas.
c) Next, the manufacturing method of the hydrogen separator 1 of a present Example is demonstrated.
<Powder filling process>
In this embodiment, press molding is performed using a mold 61 as shown in FIG. A cylindrical inner hole 65 corresponding to the outer shape of the hydrogen separator 1 is formed at the axial center of the cylindrical rubber mold 63 of the mold 61, and hydrogen separation is performed at the axial center of the inner hole 65. A cylindrical (test tube shape) center pin 67 corresponding to the shape of the center hole 3 of the body 1 is provided upright. Thereby, a substantially cylindrical mold hole 69 is formed.

Therefore, in this embodiment, the material for forming the porous support 5 is filled in the mold hole 69 of the rubber mold 63, that is, yttria-stabilized zirconia in which 50% by volume of organic beads are added as a pore former. (YSZ) The granulated powder was filled.
<Pressurization process>
Next, as shown in FIG. 6B, the upper mold 73 was fixed to the upper part of the rubber mold 63. The upper die 73 is formed with a concave portion 75 having a shape corresponding to the tip of the porous support body 5, and the porous mold having the same shape as the porous support body 5 is formed by fitting the concave portion 75. A forming portion 77 is produced.

In this state, the bottomed cylindrical shaped body corresponding to the shape of the hydrogen separator 1 as shown in FIG. 6C is formed by press-molding by pressing at 100 MPa from the outer peripheral side of the rubber mold 63. 79 was produced.
<Temporary firing process>
Next, the bottomed cylindrical shaped body 79 is degreased, and then calcined at 1000 ° C. for 1 hour. As shown in FIG. A ceramic temporary fired body 81 (to be the support 7) was obtained.
<Dense layer formation process>
Next, as shown in FIG. 7 (a) in which the main part (C portion in FIG. 6 (d)) is enlarged, the outer peripheral surface (surface) on the base end side (downward in the figure) of the ceramic pre-fired body 81 The YSZ slurry was applied so as to cover with a predetermined width to form a layered dense layer forming portion 83 (which becomes the dense layer 11 after sintering). The YSZ slurry is a slurry obtained by adding an organic solvent to the YSZ powder. Further, as a coating method, dip coating, printing, spray coating or the like can be adopted.
<First firing step>
Next, the dense layer forming portion 83 and the ceramic pre-fired body 81 were simultaneously fired (co-fired) in the atmosphere at 1500 ° C., and the dense layer 11 was provided on the surface as shown in FIG. A porous support 5 having an outer diameter of 10 mm and a length of 300 mm was obtained.
<Total porous layer forming step>
Next, as shown in FIG. 7 (c), the entire porous layer (including the portion that will later become the porous layer 13) is formed on the outer surface of the porous support 5 by the dip coating method using the YSZ slurry. A forming portion 85 was formed.

  Specifically, over a predetermined range of the outer peripheral surface of the dense layer 11 on the tip side (upper side in the figure) and an exposed portion (the entire portion not covered with the dense layer 11) of the entire outer peripheral surface of the porous support 5. A layered total porous layer forming portion 85 was formed.

Thereafter, the total porous layer forming portion 85 was baked at 1200 ° C. in the air to obtain a total porous layer 87 as shown in FIG. Of the total porous layer 87, the inner side (left side of the figure) is the porous layer 13, and the outer side (right side of the figure: the front side) is the porous part 89 where the hydrogen separation layer 15 is formed. .
<Pd metal nucleation process>
Next, the porous support 5 (outside thereof) provided with the dense layer 11 and the total porous layer 87 is immersed in the Sn ion solution, and Sn ions are adsorbed on the surface side of the total porous layer 87, and then washed with water. Then, it was immersed in a Pd ion solution, and Pd ions were adsorbed by an exchange reaction between Sn ions and Pd ions.

  Then, Pd ions were reduced by dipping in a hydrazine solution to form Pd metal nuclei. That is, Pd metal nuclei were attached to the inner peripheral surface of the pores 21 on the surface side of the total porous layer 87 (see FIG. 7F).

In addition, when immersing in each said solution, it is suitable to make the inner side (center hole 3 side) of the porous support body 5 into a pressure lower than an outer side.
<Protective layer forming step>
Next, as shown in FIG. 7E, the above-described YSZ slurry is again dip-coated on the whole porous layer 87 to which the Pd metal nuclei are adhered, and then baked at 1200 ° C. A porous total protective layer 88 (part of which becomes the protective layer 17) was formed.
<Electroless plating process>
Next, Pd metal nuclei attached on the surface side in the whole porous layer 87 are grown by electroless plating (chemical plating), and the main part (D in FIG. 7 (e) is shown in FIG. 7 (f). As shown in an enlarged view, an electroless plating layer 91 made of Pd and having a thickness of 2.5 μm was formed so as to fill part of the pores 21.

  Specifically, in this electroless plating method, the tip side of the porous support 5 (the range in which the outer total porous layer 87 and the total protective layer 88 are formed) is electroless Pd plating solution having a bath temperature of 60 ° C. (Palladium compound: concentration 2 g / L) was set and electroless plating was performed for 20 minutes to form an electroless plating layer 91. In the case of performing electroless plating, it is more preferable that the inner side (center hole 3 side) of the porous support 5 is set to a lower pressure than the outer side.

The porous support 5 having the entire porous layer 87 and the entire protective layer 88 (including the electroless plating layer 91) on the surface is hereinafter referred to as a composite support 93.
<Electrolytic plating process>
Next, as shown in FIG. 8, an aqueous NaCl solution having a concentration of 6.0 mol / L was introduced into the central hole 3 of the porous support 5 (and hence the composite support 93) as an electrolyte.

  Further, after inserting the feeding electrode 95 in the NaCl electrolyte, the composite support 93 is placed in an electrolytic Ag plating solution (silver nitrate solution: concentration 37 g / L) at a bath temperature of 30 ° C. in which the counter electrode 97 is previously disposed. I set it. The electrolytic Ag plating solution is supplied to the outer side of the entire protective layer 88 (the right side in FIG. 8).

Then, constant current electrolytic plating was performed for 2.0 minutes at a current value (current density) of 0.3 A / dm ² , and an electroplating layer 99 that is an Ag plating film was formed on the electroless plating layer 91. A metal part forming body 101 (to be a hydrogen separation metal part 16) was produced.

The electrolytic plating layer 99 is also formed on a part of the inner side of the entire protective layer 88, but as a product, the outer porous part not filled with the plating metal is the protective layer 17.
Further, in this electrolytic plating, electrons are supplied to the electroless plating layer 91 via the electrolytic solution supplied to the center hole 3 inside the porous support 5 (and hence the pore 103 of the porous support 5). The plating metal (Ag in this case) is supplied to the outside of the electroless plating layer 91 through the electrolytic Ag plating solution supplied to the outside of the entire protective layer 88 (therefore, the pores 105 of the entire protective layer 88).

  Then, after the electrolytic plating, the metal part forming body 101 was heat-treated in nitrogen at 750 ° C. to alloy Pd and Ag to form a hydrogen separation metal part 16 made of a PdAg alloy having a thickness of 4 μm. As a result, a hydrogen separation layer 15 having a thickness of 4 μm was formed.

  In the total porous layer 87, the inner side (left side in the figure) where the hydrogen separation layer 15 is not formed becomes the porous layer 13, and the outer side (surface side: right side in the figure) in the total porous layer 87 is hydrogen. The separation layer 15 is formed. Further, the inner side of the total protective layer 88 is also the hydrogen separation layer 15, and the outer side of the total porous layer 88 is the protective layer 17. That is, the hydrogen separation layer 15 is configured to extend over the entire porous layer 87 and the entire protective layer 88 (part of them).

Through these steps, the hydrogen separator 1 was completed.
d) Next, a method for manufacturing the hydrogen separator 31 provided with the hydrogen separator 1 will be briefly described.
<Manufacturing process of seal layer 35>
When the first and second seal members 35a and 35b are manufactured, for example, a sheet made of expanded graphite is wound (a mandrel or the like not shown) to form a cylindrical laminate (the mandrel or the like is removed later). ).

Next, this laminated body is oxidized with an oxidizing agent such as concentrated sulfuric acid and nitric acid to expand the interlayer distance in the expanded graphite by, for example, about 100 to 300 times.
Thereafter, the expanded graphite is loaded and compressed by press molding so that the density range is, for example, 0.6 to 1.9 g / cm ³ .

  In the case of manufacturing the third seal member 35c, a borosilicate glass powder (average particle size of 10 μm) is used and formed into a pellet at a press pressure of 30 MPa using a uniaxial press molding machine. The pellet-shaped molded body is further subjected to pressure molding at 360 MPa using a CIP molding machine, and then fired at 570 ° C. The inner diameter, outer diameter, upper surface, and bottom surface of the pellet after firing are ground to obtain a glass ring having a desired size.

In press molding, a glass powder may be mixed with a binder and granulated. Moreover, it is good also as a glass ring of desired shape without the process after baking by calculating the shrinkage | contraction by baking beforehand, press-molding in a ring shape, and baking.
<Assembly method of hydrogen production apparatus 21>
As shown in FIG. 4, the gasket 50 of the second seal member 35b, the glass ring of the third seal member 35c, the gasket of the first seal member 35a, and the press fitting 37 are fitted in the space 50 of the mounting bracket 33 in this order. .

  Next, the open end side of the hydrogen separator 1 is inserted so as to pass through the through holes of the press fitting 37, the first seal member 35a, the third seal member 35c, and the second seal member 35b. The end is fitted to the mounting bracket 33.

  Next, the fixing metal fitting 39 is fitted from the front end side of the hydrogen separator 1, the screw portion inside the fixing metal fitting 39 and the screw portion outside the mounting metal fitting 33 are screwed together, and the pressing metal fitting 37 is fixed by the fixing metal fitting 39. The hydrogen production apparatus 31 is completed by tightening to the base end side.

  In this way, the metal separator 51 or the like was attached to the hydrogen separator 1 to form the hydrogen separator 31, and the hydrogen separator 21 was fixed to the metal container 53 by the metal joint 51 to form the hydrogen separator module 55.

e) Next, the effect of the present embodiment will be described.
In this embodiment, the hydrogen separation layer 15 is a mixed layer containing a ceramic and a hydrogen separation metal, and the interface at the end in contact with the dense layer 11 (interface on the hydrogen separation layer 15 side) is made of ceramic. It is composed of a porous substrate 19 and a hydrogen separation metal filled in the pores 21 of the porous substrate 19.

  That is, the interface (end surface in contact with the dense layer 11) on the hydrogen separation layer 15 side has a dense structure in which the pores 21 of the porous substrate 19 are filled with the hydrogen separation metal, and thus the dense layer 11 and the hydrogen separation layer 15. Is firmly joined without a gap, and therefore, there is a remarkable effect that gas leakage at the interface can be reduced. Thereby, the purity of hydrogen to be separated can be increased (for example, to 99.99% or more).

  In particular, when hydrogen is separated from the raw material gas, a differential pressure is provided between the outer side and the inner side of the hydrogen separator 1 (so that the pressure on the raw material gas side becomes higher). By using the example hydrogen separator 1, gas leakage can be suitably prevented.

  In addition, in this embodiment, since the close contact between the dense layer 11 and the hydrogen separation layer 15 is high, the durability is high with respect to the thermal cycle such as long-time operation and frequent start / stop of the hydrogen separation device 31 and the like. (Airtightness).

  Furthermore, in this embodiment, by providing the dense layer 11, the bonding area between the hydrogen separation layer 15 and the dense layer 11 and the bonding area between the dense layer 11 and the mounting bracket 33 (specifically, the seal layer 35) are increased. (The bonding area can be arbitrarily adjusted in the manufacturing process), and high airtightness can be ensured even in an environment of high temperature and high pressure.

In addition, in the present embodiment, the surface of the dense layer 11 is smoother than the surface of the porous support 5. Therefore, the airtightness in the seal layer 35 can be enhanced.
In addition, in this example, the total porous layer 87 (including the porous layer 13 and the hydrogen separation layer 15), the formation of the Pd nucleus, the formation of the protective layer 17, the Pd plating, the Ag plating, There is a step of attaching Pd nuclei between the formation of the mass layer 87 and the formation of the protective layer 17. That is, Pd nuclei are formed in advance in the total porous layer 87, and at the time of Pd plating, Pd nuclei are blocked from the Pd nuclei as a starting point so as to block some pores of the total porous layer 87 and the protective layer 17. Grow into a dense hydrogen separation layer 15.

  As described above, since Pd nuclei exist between the porous layer 13 and the protective layer 17, there is no restriction on the width and layer thickness where the dense layer 11 and the porous layer 13 overlap, and when the width A1 is long (for example, 2 mm Even when the thickness A2 of the porous layer 13 is thick (for example, 5 μm or more), high airtightness can be ensured. For example, even when the layer thickness A2 of the porous layer 13 on the dense layer 11 is 10 μm and the overlapping width A1 of the dense layer 11 and the porous layer 13 is 5 mm, the dense hydrogen separation layer 15 without gas leakage is formed into the dense layer 11. Can be formed on top.

  However, the layer thickness A2 of the porous layer 13 and the overlapping width A1 of the dense layer 11 and the porous layer 13 are in a trade-off relationship with the gas permeation performance and the hydrogen separation performance. It is better to set the thickness and width.

  Furthermore, in this embodiment, the width A3 where the dense layer 11 and the hydrogen separation layer 15 are in contact is 1 to 10 μm. The contact surface width (contact width) A3 has a width equal to or greater than the thickness of the hydrogen separation layer 15 formed on the porous support 5 (actually on the porous layer 13). Yes. As with the thickness of the hydrogen separation layer 15, the contact width A3 can be controlled by the nucleation conditions for forming Pd nuclei on the porous layer 13 and the Pd plating conditions.

  For example, by increasing the plating time, the thickness of the hydrogen separation layer 15 is increased, and the contact surface between the dense layer 11 and the hydrogen separation layer 15 is increased (the contact width A3 is increased). When the thickness of the hydrogen separation layer 15 is thick, the contact surface is wide, which is suitable for gas leakage.

However, since the layer thickness of the hydrogen separation layer 15 is in a trade-off relationship with the gas permeation performance and the hydrogen separation performance, the layer thickness may be appropriately controlled according to the purpose of use.
In addition, in this embodiment, since the porous protective layer 17 is provided on the surface of the hydrogen separation layer 15, poisonous substances adhere to the hydrogen separation layer 15 (specifically, hydrogen separation metal), and hydrogen purity is improved. It can be prevented from lowering.

In addition, in this embodiment, the seal layer 35 and the mounting bracket 33 that is a metal member are arranged away from the hydrogen separation layer 15. Therefore, various materials (for example, brazing material and glass) that can react with the hydrogen separation layer 15 (specifically, hydrogen separation metal) can be used as the material of the seal layer 35.
[Experimental example]
Next, experimental examples conducted for confirming the effects of the present invention will be described.

As a hydrogen separator used for the experiment, a hydrogen separator similar to that in Example 1 was prepared. Moreover, the hydrogen separator 111 shown in FIG. 9 was produced as a comparative example.
The hydrogen separator 111 of this comparative example is greatly different from the first embodiment in that it does not have a dense layer. That is, the porous layer 125, the hydrogen separation layer 127, and the protective layer 129 are sequentially laminated in the same manner as in the first embodiment so as to cover the entire outer surface of the porous support 123 similar to the first embodiment. Yes.

  Further, a seal layer 131 made of annular expanded graphite is disposed on the outer peripheral surface of the base end side of the hydrogen separator 111, and the hydrogen separator 111 is attached to the mounting bracket 133 in a state of being gas-sealed by the seal layer 131. It is fixed. Thereby, the hydrogen separator 135 is configured.

And the underwater He leak test was done using the hydrogen separator of the said Example 1 and a comparative example.
In this underwater He leak test, each hydrogen separator is placed in the water from the tip side to the portion (joint) where the hydrogen separator and the mounting bracket are in contact via a seal layer, and hydrogenated at room temperature. When 1.0 MPaG He gas was supplied to the inside (center hole) of the separator, it was examined whether or not He gas (bubbles) leaked from the outside of the hydrogen separator.

As a result, no leak of He gas was observed from the hydrogen separator using the hydrogen separator of Example 1. On the other hand, in the hydrogen separation layer using the hydrogen separator of the comparative example, gas leakage was observed between the mounting bracket and the hydrogen separator.
[Modification 1]
Next, a first modification of the first embodiment will be described, but a description of the same contents as the first embodiment will be omitted.

As shown in FIG. 10A, in the first modification, the hydrogen separator 143 similar to that in the first embodiment is attached to the hydrogen separator 141.
In particular, the first modification is basically the same as the first embodiment, but the configuration of the seal layer 145 is different.

Specifically, a ring-shaped gasket made of expanded graphite similar to the first seal member (or second seal member) of the first embodiment is used as the seal layer 145.
Similar to the first embodiment, the seal layer 145 is disposed in a space 149 between the outer peripheral surface on the proximal end side of the hydrogen separator 143 and the inner peripheral surface on the distal end side of the mounting bracket 147, and the fixing bracket 151 and The pressing metal 153 is pressed and fixed.

  Also in this example, as in Example 1, the sealing layer 145 provided on the dense layer 155 does not come into contact with the surface layer 157 made of a protective layer, a hydrogen separation layer (not shown), or the like. Further, it is disposed on the dense layer 155.

Also according to this embodiment, the same effects as those of the first embodiment can be obtained.
[Modification 2]
Next, a second modification will be described, but the description of the same contents as those in the first embodiment will be omitted.

As shown in FIG. 10B, in the second modification, the hydrogen separator 163 similar to that in the first embodiment is attached to the hydrogen separator 161.
Specifically, as in the first embodiment, a dense layer 167 is provided on the outer peripheral surface of the base end side of the porous support 165, and covers the distal end side of the dense layer 167 and the exposed portion of the porous support 165. Thus, a surface layer 169 composed of a porous layer, a hydrogen separation layer, and a protective layer (not shown) similar to that in Example 1 is formed.

  In particular, in this embodiment, the hydrogen separator 163 (specifically, the dense layer 167) is joined to, for example, a stainless steel metal member 173 via an annular brazing material layer 171. The brazing material layer 171 and the surface layer 169 are formed separately so as not to contact each other.

  The material of the brazing material layer 171 is not particularly limited as long as the material can join the dense layer 167 and the metal member 173. For example, a well-known hard wax, a soft wax, etc. are mentioned. Examples of the soft solder include lead-tin alloy solder, and examples of the hard solder include brass solder, silver solder, nickel solder, gold solder, palladium solder and the like.

  And when joining using the brazing | wax material mentioned above, the metal member 173 provided with the through-hole 175 which can insert the hydrogen separator 163 first is produced. Next, for example, a Ni-based brazing material is applied on the dense layer 167, and this is inserted into the through hole 175 of the metal member 173 to be brazed and joined.

Also according to this embodiment, the same effects as those of the first embodiment can be obtained.
In addition, this invention is not limited to the said embodiment and Example at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.

  (1) For example, in addition to the above-described internal feeding type electrolytic plating, normal electrolytic plating can be employed. In this case, one electrode is attached to the Pd metal layer or the like formed in the entire porous layer with a clip or the like so as to be conductive, and electrolytic plating can be performed as usual.

That is, electrolytic plating can be performed by supplying a plating solution between a metal layer (with one electrode attached) and the other electrode and applying a voltage between the two electrodes.
(2) In the case of the internal power feeding method, the electrolytic solution may be supplied to the outside of the ceramic support, and the electrolytic plating solution may be supplied to the inside to deposit the plating metal from the inside (center hole side). .

  (3) The raw material gas such as natural gas is reformed (for example, steam reforming) in the hydrogen separator of each of the above embodiments (for example, a porous support) to form a hydrogen-rich reformed gas (Ni Or the like) may be added.

DESCRIPTION OF SYMBOLS 1, 111, 143, 163 ... Hydrogen separator 5, 123, 165 ... Porous support 11, 167 ... Dense layer 13, 125 ... Porous layer 15 ... Hydrogen separation layer 17, 129 ... Protective layer 19 ... Porous substrate 21: Fine holes 33, 133, 147 ... Mounting brackets 35, 131, 145, 171 ... Seal layers

Claims (4)

A porous support made of ceramic that allows gas to pass through;
A dense layer made of a ceramic formed on a part of the surface of the porous support and having airtightness;
A porous layer made of ceramic that covers a region of the surface of the porous support that is not covered with the dense layer and a part of the dense layer, and that allows the gas to pass through,
A hydrogen separation metal having a hydrogen separation metal that allows only hydrogen to pass through a gas containing hydrogen, covers the porous layer, and has its end bonded to the dense layer; and
In a hydrogen separator comprising
The hydrogen separation layer is a mixed layer containing a ceramic and the hydrogen separation metal, and an interface at the end contacting the dense layer fills a porous substrate made of the ceramic and pores of the porous substrate. And a hydrogen separator made of the hydrogen separating metal.   2. The hydrogen separation layer as a whole is composed of a porous substrate made of the ceramic and the hydrogen separation metal filled in pores of the porous substrate. The hydrogen separator described.   The hydrogen separation layer covers the surface of the hydrogen separation layer, and has a configuration in which an end portion of the hydrogen separation layer is bonded to the dense layer, and includes a protective layer capable of passing the hydrogen and protecting the hydrogen separator. The hydrogen separator according to claim 1 or 2.   An airtight seal layer is disposed in close contact with the surface of the dense layer away from the hydrogen separation layer, and a metal member is disposed in close contact with the seal layer interposed therebetween. The hydrogen separator according to any one of claims 1 to 3, wherein: