JP2008246317A - Hydrogen separator and fuel cell - Google Patents

Abstract

To provide a hydrogen separator comprising a porous support that supports a hydrogen permeable membrane and can prevent the hydrogen permeable membrane from peeling, swelling or pores even in a high temperature environment. .
A porous support having a cylindrical shape that opens at both ends or one end or a plate shape, and a hydrogen that covers the surface of the porous support and allows hydrogen to permeate selectively. A method for producing a hydrogen separator, comprising: a permeation membrane, wherein a smooth recess is formed by grinding a recess having a corner that is present on a surface of the porous support that is covered with the hydrogen permeation membrane.
[Selection] Figure 5

Description

  The present invention relates to a hydrogen separator and a fuel cell, and more particularly, a hydrogen separator in which a porous support that supports a hydrogen permeable membrane does not cause pinholes or the like that cause gas leakage even under a high temperature environment. The present invention also relates to a fuel cell that can extract electric power using hydrogen separated by the hydrogen separator as fuel.

  Patent Document 1 discloses that an electrolytic palladium or palladium alloy plating film that completely covers the surface by electroless palladium plating after electroless palladium plating is applied to the porous ceramic layer. “A method for producing a gas separation thin film characterized by forming a coating” (see claim 1 of Patent Document 1) is described, and examples (Patent Document 1, page 2, right column to third column) are described. Page)) also describes gas separation membranes obtained using this production method.

  Patent Document 2 states that “in the method of forming a Pd hydrogen separation membrane on the surface of a metal porous body, first, electro Ni plating is performed on the surface of the metal porous body, and then electro Pd plating is performed on the Ni plating layer. “A method for producing a hydrogen separation membrane, wherein electroless Pd plating is performed on the electric Pd plating layer while vacuuming from the back surface of the porous metal body” (see claim 1 of Patent Document 2). Further, in Examples (see columns [0016] to [0024] in Patent Document 2), a separation membrane obtained by using this production method is also described.

  In Patent Document 3, “in the method for producing an inorganic hydrogen separation membrane for selectively permeating and separating hydrogen from a hydrogen-containing gas, after forming a thin film of palladium or an alloy mainly composed of palladium on the surface of the porous carrier, The pinhole of the thin film was probed, and the probed pinhole portion was coated with an alloy mainly composed of palladium or a metal alloying with palladium, and heat-treated at a temperature at which the deposited metal was alloyed with palladium. “Method for producing inorganic hydrogen separation membrane for producing palladium-based hydrogen separation membrane” (see claim 1 of Patent Document 3) is described, and examples (see [0015] to [0018] in Patent Document 3). Inorganic hydrogen separation membranes obtained using this production method are also described.

  By the way, depending on the use conditions of the hydrogen permeable membrane, for example, use in a high temperature environment, the hydrogen permeable membrane may be peeled off, swollen or punctured. The cause is often the porous material covered by the hydrogen permeable membrane. However, in the manufacturing methods described in Patent Documents 1 to 3, there is a description about a method for forming a hydrogen permeable membrane, but there is no description about a porous body. Even if the porous body is exposed to a high temperature environment or the like, there has been a demand for a hydrogen separation apparatus including a porous body that does not peel off, swell, or form pores on the hydrogen permeable membrane. Furthermore, a fuel cell that can extract electric power using hydrogen separated by the hydrogen separator as a fuel has been desired.

Japanese Patent Publication No. 5-53527 JP-A-5-123548 JP 2002-119834 A

  The problem to be solved by the present invention is to provide a porous support that supports the hydrogen permeable membrane and can prevent the hydrogen permeable membrane from peeling, swelling or pores even in a high temperature environment. It is to provide a hydrogen separator.

  Another problem to be solved by the present invention is to provide a fuel cell that can extract electric power using hydrogen separated by the hydrogen separator as fuel.

As means for solving the problems,
Claim 1 has a cylindrical shape that opens both ends or one end, or a porous support having a plate shape;
A hydrogen permeable membrane that covers the surface of the porous support and allows hydrogen to selectively permeate;
A method for producing a hydrogen separator, characterized in that a smooth recess is formed by grinding a recess having a corner, present on the surface of the porous support that is covered by the hydrogen permeable membrane,
Claim 2 has a cylindrical shape opening both ends or one end, or a porous support having a plate shape,
A hydrogen permeable membrane that covers the surface of the porous support and allows hydrogen to selectively permeate;
A method for producing a hydrogen separator, characterized by removing, by grinding, a convex portion having a corner, present on the surface of the porous support covered by the hydrogen permeable membrane,
The hydrogen separator according to claim 1 or 2, wherein a surface of the porous support is covered with a barrier layer, and a surface of the barrier layer is covered with a hydrogen permeable membrane. Manufacturing method,
According to a fourth aspect of the present invention, the porous support includes a reforming catalyst that generates hydrogen gas by reforming a supplied gas. It is a manufacturing method of the described hydrogen separator,
A fifth aspect of the present invention provides the hydrogen separator according to any one of the first to fourth aspects, wherein a part or all of the hydrogen permeable membrane is palladium or an alloy containing palladium. Is the way
According to a sixth aspect of the present invention, the hydrogen separator obtained from the method of manufacturing a hydrogen separator according to any one of the first to fifth aspects and an electric power generation unit capable of taking out electric power using hydrogen as a fuel are integrated. A fuel cell provided in
In a seventh aspect of the present invention, the hydrogen separator obtained from the method for manufacturing a hydrogen separator according to any one of the first to fifth aspects and a power generation unit capable of taking out electric power using hydrogen as a fuel are separated. This is a fuel cell that is provided.

  The method for producing a hydrogen separator according to the present invention removes a corner by grinding a concave or convex portion having a corner, which can become a pinhole or the like when the porous support is exposed to a high temperature environment or the like. Therefore, the hydrogen permeable membrane covering the porous support is not peeled off, swollen, or pores, and leakage of gases other than hydrogen gas can be prevented.

  Moreover, the fuel cell of this invention can take out electric power by making into use the hydrogen isolate | separated with the hydrogen separator obtained by the manufacturing method of the said hydrogen separator as a fuel.

  The method for producing a hydrogen production apparatus according to the present invention comprises a porous support and a hydrogen permeable membrane, and grinds a concave or convex portion having a corner on the surface of the porous support.

  The porous support has a cylindrical shape that opens at both ends or one end, or has a plate shape.

  The porous support is porous and allows gas to pass through the porous support, a membrane support capable of supporting a hydrogen permeable membrane described later, and the hydrogen separator according to the present invention. It does not react with a gas (hereinafter sometimes referred to as “source gas”) supplied to a hydrogen separation device (hereinafter sometimes referred to as “hydrogen separation device according to the present invention”) obtained by the above production method. Non-reactive. The porous support is formed of various materials as long as it has gas flowability, membrane supportability and non-reactivity. For example, examples of the material include inorganic oxide, carbon, and inorganic nitride. Among the materials, examples of the inorganic oxide include aluminum oxide, silica, silica-alumina, mullite, cordierite, zirconia, stabilized zirconia, and porous glass. Further, the materials can be used singly, mixed or combined.

  The porous support is formed, for example, by forming a mixture obtained by mixing graphite powder, corn starch or the like, which can be used as a pore-forming agent, with the material into a plate or cylinder, and the plate or cylinder. It can be obtained by sintering the shaped body.

  Here, the source gas may be a mixed gas containing hydrogen, or a gas that is reformed to generate hydrogen gas. Examples of the source gas include a mixed gas obtained by mixing carbon dioxide, methane, and water vapor with hydrogen gas, or a hydrocarbon gas that can generate hydrogen gas by reacting water vapor.

  When a gas that is reformed to generate a gas mainly composed of hydrogen gas is used as the raw material gas, the porous support is reacted with the raw material gas, decomposed or decomposed by steam reforming. It is preferable to have a function to be generated (hereinafter sometimes referred to as “catalyst function”). In the case where the porous support is formed in a cylindrical shape, hydrogen gas is taken out of the porous support by supplying the raw material gas into the porous support, or outside the porous support. In order to take out hydrogen gas into the porous support by supplying the raw material gas, a membrane having the catalytic function is provided on the inner surface or the outer surface of the porous support having no catalytic function. It is possible to adopt a mode in which a multi-layer structure is provided, or a mode in which metal particles having a catalytic function are supported on a porous support, but this mode complicates the manufacturing process and structure of the hydrogen separator of the present invention. The porous support having a catalytic function without adopting such an embodiment can be simplified structurally.

  The porous support having a catalytic function can be formed by mixing or combining a material necessary for forming the above-described porous support and a material having a catalytic function. As the porous support having a catalytic function, for example, a porous support to which nickel used for steam reforming of hydrocarbons is added, and as a specific example, a mixture of nickel and yttria stabilized zirconia is a main component. Examples thereof include a porous sintered body (sometimes referred to as “Ni—YSZ cermet”), porous ceramics added with nickel, or porous glass added with nickel. When a synthesis gas or a water gas is used as the raw material gas, the porous support can contain an iron and / or chromium component and the like, and a catalytic function can be expressed. The component for imparting a catalytic function to the porous support can be appropriately selected depending on the type of the raw material gas.

  Furthermore, by controlling the porosity and pore diameter of the porous support, their strength, gas permeability and the like can be adjusted.

  The porosity of the porous support is preferably 10 to 85%. When the porosity is less than 10%, the raw material gas does not flow quickly through the porous support, and the pressure loss may increase. In particular, it has a catalytic function capable of steam reforming of hydrocarbons. When a porous support is used, it may not be possible to sufficiently generate the necessary hydrogen gas by sufficiently reforming the hydrocarbon. On the other hand, when the porosity exceeds 85%, the strength of the porous support may be lowered. The porosity of the porous support in the hydrogen separator according to the present invention is a value measured by Archimedes method. The porosity of the porous support is appropriately determined based on the strength of the member, the pressure applied to the porous support by the source gas, and the like.

  The average pore diameter of the porous support is preferably 0.05 to 30 μm. When the average pore diameter is less than 0.05 μm, the raw material gas does not flow quickly through the porous support, and the pressure loss may increase. In particular, when using a porous support having a catalytic function capable of steam reforming hydrocarbons, the raw material gas cannot be sufficiently reformed to generate sufficient hydrogen gas. is there. On the other hand, when the average pore diameter exceeds 30 μm, there is a fear that sufficient strength of the porous support cannot be maintained. In addition, defects such as voids may occur in the hydrogen permeable membrane supported by the porous support, and the hydrogen permeability of the hydrogen permeable membrane may decrease. The average pore diameter of the porous support in the hydrogen separator according to the present invention is obtained by observing the surface with an electron microscope, for example, a scanning electron microscope (SEM), and approximating the pore opening to a circle. Can be calculated by arithmetic averaging.

  In order to control the porosity and average pore diameter of the porous support within the above ranges, the particle diameter, particle diameter distribution and / or firing temperature of the powder used as the material to be formed may be adjusted as appropriate.

  In the method for producing a hydrogen separator according to the present invention, the surface of the porous support whose pore diameter and the like are adjusted as described above is covered with a hydrogen permeable membrane described later, for example, the porous support is in a high temperature environment. A concave portion (hereinafter sometimes simply referred to as a “concave portion”) or a convex portion (hereinafter, sometimes referred to as “concave portion”) that may cause inconveniences such as a pinhole being caused by exposure to the surface or a hydrogen permeable membrane not being uniformly coated. In many cases, the hydrogen permeation membrane covering the porous support is peeled off, swollen, or pores due to the above disadvantages. Therefore, it is preferable to remove the concave portion or the convex portion in advance before coating the porous support with the hydrogen permeable membrane. Since the porous support of the hydrogen separator according to the present invention is formed by removing the concave or convex portions having the corners by grinding, peeling, swelling, or pores of the hydrogen permeable membrane covering the porous support are generated. hard.

  Here, the corner part of the concave part or the convex part means a part where the hydrogen permeable film may be peeled off or cracked from the corner part when the surface is covered with the hydrogen permeable film. As a corner | angular part, the opening sharp part of the recessed part in the porous support surface, or the protrusion part of the internal surface in the recessed part of the porous support surface etc. can be illustrated, for example. The corners are round when the porous support is viewed microscopically, but also include sites that may cause inconveniences such as peeling off the hydrogen permeable membrane.

  Here, the recessed part or convex part of a porous support body can be discovered as follows. First, a porous support is formed as a cylinder or a plate with the above-described materials. Next, by irradiating the surface of the porous support covered with the hydrogen permeable membrane with light, the shadow caused by the irregularities on the surface is observed, and the concave or convex portions are removed. Discriminate. The light applied to the surface of the porous support is preferably light that does not adversely affect the eyeball when observing the surface. For example, illumination light or the like can be used. Furthermore, by irradiating the surface of the porous support with light from a plurality of directions, the shadows of the recesses or protrusions on the surface are generated in a plurality of directions, so that the positions of the recesses or protrusions can be easily identified and discovered. Become. Further, the surface of the porous support irradiated with light is not particularly limited as long as an observation means capable of finding irregularities on the surface is used, and can be observed with a microscope or a magnifying glass, for example.

  The found concave or convex portion is ground and removed. For grinding the concave portion or convex portion to be found, it is preferable to use a member capable of shaving the surface of the porous support, for example, a grinder equipped with cemented carbide, diamond or the like as an abrasive and an abrasive.

  Below, the recessed part or convex part of a porous support body is demonstrated using drawing. 1 (A) to (D) and FIGS. 2 (A) and 2 (B) show a state in which a porous support is provided on the lower side and a hydrogen permeable membrane covers the upper surface thereof. ing.

  1 (A) to 1 (D) show a porous support having a concave portion and a surface covered with a hydrogen permeable membrane.

  FIG. 1A shows a state in which the surface of a concave portion having a corner is covered with a hydrogen permeable membrane. As shown in FIG. 1A, the thickness of the hydrogen permeable membrane is not uniform, and the convex portion of the concave portion of the porous support has a reduced thickness of the hydrogen permeable membrane. It is considered that the strength is lowered, and the hydrogen permeable membrane is likely to crack, and as a result, gas other than hydrogen gas can be leaked.

  FIG. 1B shows a state in which a hydrogen permeable film is coated on the surface of a recess having an inclined gradient. As shown in FIG. 1 (B), since a portion where the hydrogen permeable membrane is not coated is generated, it is considered that gas leakage occurs from a portion where the hydrogen permeable membrane is not coated.

  FIG. 1C shows a state in which the surface of a recess having an internal diameter larger than the opening diameter is covered with a hydrogen permeable membrane. As shown in FIG. 1C, the hydrogen permeable membrane is not coated with a uniform thickness, and there is a difference in hydrogen permeation performance between the thin portion and the thick portion of the hydrogen permeable membrane, or the hydrogen permeable membrane. It is considered that the swells, peels off, or has holes or the like in the thin part. The concave portion shown in FIG. 1 (C) is round and round when viewed microscopically. However, when the hydrogen permeable membrane is coated as described above, the hydrogen permeable membrane is swollen or peeled off. Etc. may occur, and therefore, they are included in the recesses having corners.

  FIG. 1D shows a state where the surface of the concave portion having a hole shape is covered with a hydrogen permeable membrane. As shown in FIG. 1D, the hydrogen permeable membrane does not cover the inside of the recess, and the inside of the recess is hollow, so that the gas inside the recess presses the hydrogen permeable membrane outward. Thus, it is considered that the hydrogen permeable membrane may swell.

  Further, FIGS. 2 (A) and 2 (B) show a porous support having a convex portion and having a surface covered with a hydrogen permeable membrane.

  FIG. 2A shows a state in which the surface of a convex portion having a corner at the top is covered with a hydrogen permeable membrane. As shown in FIG. 2A, the thickness of the hydrogen permeable membrane is not uniform, and the thickness of the hydrogen permeable membrane is small at the top of the convex portion of the porous support. This is likely to cause a crack in the hydrogen permeable membrane, which may result in leakage of gases other than hydrogen gas.

  FIG. 2 (B) shows a state where the surface of the convex part having an inclined gradient is covered with a hydrogen permeable membrane. As shown in FIG. 2B, the thickness of the hydrogen permeable membrane is not uniform, and the edge of the convex portion of the porous support has a reduced thickness. This is likely to cause a crack in the hydrogen permeable membrane, which may result in leakage of gases other than hydrogen gas.

  FIGS. 3 and 4 show the porous support in a state where the concave and convex portions shown in FIGS. 1 and 2 are removed by grinding. Specifically, the porous support from which the recesses shown in FIGS. 1A to 1D are removed is shown in FIGS. 3A to 3D, and the protrusions shown in FIGS. 2A and 2B. FIGS. 4A and 4B show the porous support from which the part has been removed. Moreover, the broken line shown by FIG. 3 and 4 has shown the state of the porous support body before grinding, ie, the surface of the porous support body of FIG.

  3 (A) to 3 (D) show a smooth recess formed by smooth grinding of the porous support, and FIGS. 4 (A) and 4 (B) have a protrusion. A porous support is shown that has been ground so that the points are slightly concave. The convex portions shown in FIGS. 2A and 2B may be smoothly ground.

  As shown in FIGS. 3 (A) to 3 (D) and FIGS. 4 (A) and 4 (B), the porous support is ground by removing the corners so as to remove the corners. The surface of the body can be uniformly coated with the hydrogen permeable membrane, and the hydrogen permeable membrane can be prevented from being peeled off, swelled, or punctured.

  The hydrogen permeable membrane covers the surface of the porous support and can selectively permeate hydrogen.

  The material of the hydrogen permeable membrane that can be employed in the hydrogen separator of the present invention may be a membrane that selectively permeates hydrogen gas in a gas, such as palladium, palladium alloy, “inorganic chemical nomenclature IUPAC 1990”. Metals such as Group 5 elements of the periodic table described in “Year Recommendation” (translated on March 26, 1993, author Kazuo Yamazaki) or alloys containing these elements are used. Examples of the Group 5 element include V, Nb, and Ta. Examples of the palladium alloy and the metals other than the Group 5 element contained in the alloy containing the Group 5 element include, for example, “Inorganic Chemical Nomenclature IUPAC 1990 Recommendation” (published on March 26, 1993) Group 3 elements (including lanthanoid elements), Group 8 elements, Group 9 elements, Group 10 elements, Group 11 elements or combinations of two or more of these in the periodic table described in Kazuo Yamazaki) Can be mentioned. The group 3 element of the periodic table can include Y, the lanthanoid element can include Ce, Sm, Gd, Dy, Ho, Er, Yb, and the like, the group 8 element can include Ru, Examples of the Group 9 element include Rh and Ir, examples of the Group 10 element include Pt, and examples of the Group 11 element include Cu, Ag, and Au. The hydrogen permeable film is formed by, for example, a vacuum deposition method, an electroless plating method, a sputtering method, or the like. The thickness of the hydrogen permeable membrane is determined by the required hydrogen separation performance, for example, the hydrogen gas permeation rate and gas selectivity, and the mechanical strength of the hydrogen permeable membrane, and is preferably adjusted to 1 to 30 μm, for example. By adjusting the thickness of the hydrogen permeable membrane, for example, it is possible to withstand the pressure generated when gas permeates the hydrogen permeable membrane and the porous support. In addition, it is desirable that the entire hydrogen permeable membrane be formed of the same component from the detection of the reduction in the number of steps for manufacturing the hydrogen separator of the present invention.

  The entire surface of the porous support is covered with a hydrogen permeable membrane in the region of the porous support where gas needs to permeate from one surface to the other. This is because if the surface of the region is not sufficiently covered with the hydrogen permeable membrane and there is an exposed portion on the porous support, components other than hydrogen gas leak from the exposed portion, and the gas collected as hydrogen gas This is because the hydrogen purity decreases as a result.

  When the porous support contains the metal having the catalytic function, the metal contained in the porous support penetrates into the hydrogen permeable membrane depending on the use environment of the hydrogen separator of the present invention. In this state, the hydrogen permeation capacity of the hydrogen permeable membrane is reduced, or conversely, the metal that forms the hydrogen permeable membrane, for example, palladium is dissolved in the metal in the porous support such as nickel, and the porous support. It is conceivable that a state in which the hydrogen permeability of the hydrogen permeable membrane is reduced and the hydrogen permeability of the hydrogen permeable membrane is lowered is caused. It is necessary to prevent unexpected interaction between the metal contained in the porous support and the metal in the hydrogen permeable membrane in an environment that may cause such a state or even in such an environment. Under the circumstances, when the hydrogen separator according to the present invention is used, the occurrence of the interaction can be prevented by providing a porous barrier layer between the porous support and the hydrogen permeable membrane.

  The barrier layer is formed of a porous material that prevents mutual diffusion of the metal component of the material forming the porous support and the metal component of the material forming the hydrogen permeable membrane and allows gas to flow therethrough. For example, it is formed of an inorganic oxide or the like. Examples of the inorganic oxide include zirconia, stabilized zirconia, partially stabilized zirconia, aluminum oxide, magnesium oxide, lanthanum calcium, lanthanum chromite, lanthanum strontium, and mixtures or compounds thereof. Moreover, this barrier layer may be formed of the same material as the porous support. The barrier layer only needs to be in a porous state when the hydrogen separator according to the present invention is used, and does not necessarily have to be in a porous state when the barrier layer is formed.

  The barrier layer can be formed on the surface of the porous support using a material such as zirconia as described above, for example, by a dip coating method, a spray spraying method, a printing method, or the like. In addition, a metal having a catalytic function that is present in a region from the surface of the porous support to which a hydrogen permeable membrane is to be formed in the porous support having a catalytic function and having a catalytic function is removed by a dissolution removal method. In other words, the barrier layer may be formed by performing a barrier layer forming process. As a method for dissolving and removing the catalyst metal when performing such a barrier layer forming treatment, for example, a catalyst function-retaining metal contained in a porous support having a catalytic function from a portion where the barrier layer of the porous support is to be formed is used. The method of eluting using a solvent or a reactive agent etc. can be mentioned. The solvent and the reactant used at this time are not particularly limited as long as the metal can be eluted. For example, when a porous support containing a metal having a catalytic function is formed of the Ni-YSZ cermet, Ni present in the vicinity of the surface of the porous support is removed using an acid such as sulfuric acid or hydrochloric acid. Can be eluted. The thickness of the barrier layer is not particularly limited as long as the material components forming the metal as a catalyst present in the porous support and the metal present in the hydrogen permeable membrane do not diffuse to each other, For example, it is adjusted to 5 to 100 μm. When the thickness of the barrier layer is less than 5 μm, mutual diffusion of the material components forming the porous support and the hydrogen permeable membrane may not be prevented. On the other hand, when the thickness exceeds 100 μm, the smoothness of the hydrogen permeable member may be prevented. May hinder proper hydrogen permeation and reduce the hydrogen production function of the porous support.

  The barrier layer covers the surface of the porous support so as to isolate the porous support having a catalytic function from the hydrogen permeable membrane, and the hydrogen permeable membrane covers the surface of the barrier layer.

  Furthermore, by improving the surface state of the barrier layer, a thin hydrogen permeable film that maintains high hydrogen permeation performance can be formed. As a method for improving the surface state of the barrier layer, a method of providing a coating layer between the porous support and the barrier layer can be mentioned.

  As a material for forming the coating layer, a material for forming a porous support having the catalytic function can be used. For example, a sintered body (Ni--) having a mixture of nickel and yttria stabilized zirconia as a main component. YSZ cermet etc.), porous ceramics, porous cermet and the like. When the coating layer is formed of these materials, the raw material gas can be modified by this coating layer even if the porous support does not have a catalytic function. Among these materials, the same material as the material of the porous support having a catalytic function is preferable. By doing so, the reforming catalyst function can also be imparted to the coating layer, so that the performance of the hydrogen production apparatus can be maintained even if the coating layer is formed thicker.

  The thickness of the coating layer is not particularly limited as long as the surface state of the barrier layer can be improved. The layer thickness is adjusted to 0.1 μm or more, for example. When the thickness of the coating layer is less than 0.1 μm, the surface state of the barrier layer may not be effectively improved. On the other hand, the upper limit of the film thickness of the coating layer is not particularly limited. The film thickness can be adjusted to 100 μm, for example.

  It is preferable that pores having an average pore size smaller than the average pore size of the pores on the surface of the porous support are formed on the surface of the coating layer. The average pore diameter of the pores formed on the surface of the coating layer is not particularly limited as long as it is smaller than the average pore diameter of the pores on the surface of the porous support, but the average pore diameter of the pores on the surface of the porous support is not limited. And larger than the average pore diameter of the pores on the surface of the barrier layer.

  The average pore diameter of pores formed on the surface of the coating layer and having such a relationship is preferably 0.05 to 10 μm. If the average pore diameter is less than 0.05 μm, it may hinder the permeation of hydrocarbon gas, while if it exceeds 10 μm, the surface state of the barrier layer formed on the coating layer may not be effectively improved. is there. The average pore diameter of the pores on the surface of the coating layer is more preferably 0.05 to 8 μm, and further preferably 0.05 to 7 μm.

  Here, the average pore diameter of the pores existing on the surface of the coating layer is defined as a value calculated in the same manner as the average pore diameter of the pores on the surface of the porous support. That is, the average pore diameter is calculated by observing the surface of the coating layer with an electron microscope such as a scanning electron microscope (SEM), and arithmetically averaging the opening diameter obtained by approximating the pore opening to a circle. be able to.

  Moreover, it is preferable that pores are formed on the surface of the coating layer so as to be larger than the number of pores on the surface of the porous support. The number of pores formed on the surface of the coating layer is not particularly limited as long as it is larger than the number of pores on the surface of the porous support. The specific number of pores is preferably adjusted so that the gas permeation amount per unit time of the porous support is approximately the same. Thus, when the number of pores on the surface of the coating layer is adjusted, the gas permeation amount can be maintained. In particular, when a porous support having a catalytic function is used, the gas permeation amount of the hydrogen separator can be maintained without hindering the catalytic function of the porous support.

  Here, the number of pores existing on the surface of the coating layer can be obtained by observing the surface and counting the number of pore openings per unit area in the same manner as the calculation of the average pore diameter.

  On the surface of the coating layer, pores having an average pore size smaller than the average pore size of the pores on the surface of the porous support are formed to be larger than the number of pores on the surface of the porous support. In this case, the surface state of the barrier layer can be further effectively improved.

  In order to adjust the average pore diameter of the pores existing on the surface of the coating layer, and further the number thereof within a predetermined range, for example, the type, size, blending amount, etc. of the pore-forming agent to be blended with the porous material What is necessary is just to adjust suitably, or just to adjust suitably the particle size and / or baking temperature of the powder used as a material which forms a coating layer.

  Below, an example of the hydrogen separator obtained by the manufacturing method of the hydrogen separator of this invention is shown.

  In one embodiment of the hydrogen separator 1 shown in FIG. 5, the hydrogen separator 1 includes a hydrogen separator 2 and an attachment 3. The hydrogen separation unit 2 includes a porous support 4 that is open at one end and has a concave or convex portion removed, and a hydrogen permeable membrane 5 formed on the outer surface thereof. Since the porous support 4 shown in FIG. 5 is porous, gas can flow from, for example, the inside to the outside of the porous support 4 and supports the hydrogen permeable membrane 5. Moreover, the attachment part 3 is a member to which the hydrogen separation part 2 shown in FIG. 5 is attached, and it is preferable to use a member that does not transmit gas. Furthermore, in the hydrogen separation apparatus 1 shown in FIG. 5, the hydrogen separation part 2 is attached to the attachment part 3 via a seal member 6. The seal member 6 can fix the hydrogen separation unit 2 at a predetermined position.

  Here, it is preferable to use a member made of a material that can be deformed to some extent as a seal member that can be used in the hydrogen separator obtained by the method of manufacturing a hydrogen separator of the present invention. Since the porous support and the hydrogen permeable membrane are fixed, even if the porous support, the hydrogen permeable membrane and the seal member undergo a volume change due to heat or the like, the porous support due to deformation of the seal member or the like. It is possible to prevent the hydrogen separation part from being destroyed due to the load applied to the joint part.

  A raw material gas introduction unit 7 is inserted inside the hydrogen separation unit 2 so that the raw material gas can be supplied to the hydrogen separation unit 2. Further, in the hydrogen separator 1 shown in FIG. 5, as a member provided as appropriate, a hydrogen gas deriving unit 8 (not shown in FIG. 6) for deriving the separated hydrogen gas and hydrogen gas from the source gas are used. A residual gas deriving unit 9 (not shown in FIG. 6) for deriving the separated gas is provided.

  The hydrogen separator 1 shown in FIG. 6 is different from the hydrogen separator 1 shown in FIG. 5 in that the porous support 4 has a cylindrical shape with both ends open. Except for this, the embodiment is the same as in FIG. As shown in FIG. 6, since the porous support 4 has a cylindrical shape with both ends open, there is no need to provide a member shown as the source gas introduction part 7 in FIG. 5, and the porous support 4 The material itself is a material gas introduction member.

  Furthermore, the aspect in which the porous support 4 is formed in a plate shape is shown in FIG. In FIG. 7, the hydrogen separator 2 is formed in a plate shape, and the hydrogen permeable membrane 5 is formed on the surface of the porous support 4. A seal member 6 is provided on the edge of the porous support 4 on the porous support 4 side. Further, a pair of frames 10 are provided outside the hydrogen separator 2, and the frame 10 faces the raw material gas inlet 7 and the hydrogen permeable membrane 5 on the side facing the porous support 4. A hydrogen gas lead-out portion 8 is provided on the side where the head is located. The frame body 10 is integrated by an appropriate method such as pressure bonding, adhesion, or screw contact. In the hydrogen separator 1 shown in FIG. 7, a seal member 6 is disposed between the frame body 10 and the hydrogen permeable membrane 5. When the frame member 10 is pressed against the seal member 6 by using the seal member 6, when the cross section is trapezoidal as shown in FIG. 7, a force pressing the seal member 6 in the vertical direction and the horizontal direction acts. Thus, even when the frame body 10 is not in close contact, the hydrogen separation device 1 can be obtained in which the sealing member 6 can prevent gas leakage. When the porous support provided in the hydrogen separator obtained by the method for producing a hydrogen separator according to the present invention has a plate shape, the porous support may be, for example, a disk or a rectangular plate. It may be a shape. In addition, it is preferable to change the shape of the seal member in accordance with the shape of the porous support and to provide the seal member along the edge of the porous support, so that gas leakage can be prevented.

  As one of the apparatuses using the hydrogen separator obtained by the hydrogen separator manufacturing apparatus of the present invention, the fuel cell of the present invention can be mentioned. The fuel cell of the present invention can extract electric power using hydrogen separated by the hydrogen separator as fuel.

  A preferred example of the fuel cell according to the present invention is that the hydrogen separator and the power generator are integrally formed, and in addition to the hydrogen separator, a power generator having an anode layer, an electrolyte layer, and a cathode layer; It has. Such a fuel cell can be referred to as an integrated fuel cell. In an apparatus configuration in which a hydrogen separator and an electric power generation apparatus are integrated, it is preferable from the viewpoint of reducing the number of parts that the hydrogen permeable membrane described above is an anode in the electric power generation apparatus. An embodiment in which the porous support of the integrated fuel cell is formed in a cylindrical shape is shown in FIG. 8, and an embodiment in which the porous support is formed in a plate shape is shown in FIG.

  The fuel cell 11 shown in FIGS. 8 and 9 is preferably formed such that the hydrogen permeable membrane 5 described above has a function as an anode of the fuel cell 11. Note that the above-described metal that can be used to form the hydrogen permeable film can form a hydrogen permeable film that also functions as an anode layer.

  Next, an electrolyte layer is provided on the surface of the hydrogen permeable membrane. This electrolyte layer can conduct and pass ionized hydrogen ions by the function of the anode of the hydrogen permeable membrane. The material that can form the electrolyte layer is not limited as long as hydrogen ions can pass therethrough. For example, a perovskite type material containing at least one selected from the group consisting of Ba, Sr, Ca, Ce, and Zr. A compound can be mentioned. The electrolyte layer can be formed by adding the perovskite compound together with a binder and a dispersant to a solvent to form a slurry, applying the slurry to the surface of the hydrogen permeable membrane by screen printing or the like, and then performing a heat treatment.

Next, a cathode layer is formed on the surface of the electrolyte layer. This cathode layer functions as a cathode of the fuel cell. The material that can form the cathode layer is Ag, Pt, Ph, or A _1-X B _X CO ₃ (A is a rare earth element, B is an element including at least one of Ba, Sr, and Ca, C is an element including at least one of Co, Fe, and Mn). Similarly to the electrolyte layer, the cathode layer can be formed by preparing a slurry containing a material and applying the slurry to the surface of the electrolyte layer by screen printing or the like, followed by heat treatment.

  The electrolyte layer and the cathode layer can also be formed by a sol-gel method or a vapor deposition method.

  In the thus-formed laminate composed of the hydrogen permeable membrane having the function as an anode, the electrolyte layer, and the cathode layer, the hydrogen permeable membrane 5 having the function as the anode layer as shown in FIGS. By providing a closed circuit between the cathode layer 13 and applying a load, it is possible to form the fuel cell 11 that extracts power. Further, as shown in FIGS. 8 and 9, the hydrogen permeable membrane 5 having a function as an anode of the fuel cell 11 is provided with a connection terminal 14 so that the terminal can be easily connected.

  When the fuel cell of the present invention is formed in a cylindrical shape, as shown in FIG. 8, a porous support 4 is disposed on the inner side of the cylinder, and a barrier layer (not shown) provided as appropriate toward the outer side. ), The hydrogen permeable membrane 5, the electrolyte layer 12, and the cathode layer 13 are arranged in this order, and the source gas is circulated inside the porous support 4 and the cathode gas such as air is circulated outside the cathode layer 13. Thus, electricity can be taken out. Furthermore, the order of the layers to be arranged can be reversed, and the source gas can be circulated outside the porous support 4 and the cathode gas can be circulated inside the cathode layer 13.

  Further, when the fuel cell of the present invention is formed in a plate shape, the casing (not shown) is isolated by the fuel cell 11 shown in FIG. 9 and the raw material is provided on the porous support 4 side in the hydrogen separator 2. It is preferable to supply the gas and supply a cathode gas such as air to the hydrogen permeable membrane 5 side.

  The fuel cell according to the present invention is not limited to the integrated fuel cell. For example, the hydrogen separator according to the present invention and an anode layer, an electrolyte layer, and a cathode layer formed separately from the hydrogen separator. And a separate fuel cell having a power generation unit including a laminate formed by laminating a gas supply line for supplying the hydrogen gas extracted by the hydrogen separator to the power generation unit. An example of the separate fuel cell is shown in FIG. In FIG. 10, a hydrogen gas outlet 8 extends from a hydrogen separator similar to the hydrogen separator 1 shown in FIG. 5 and is connected to the power generator 15 and introduces a cathode gas. Is connected to a power generation unit 15, and the power generation unit 15 includes an anode layer 17, an electrolyte layer 12, and a cathode layer 13 that can extract power from hydrogen gas and cathode gas. In FIG. 10, the porous support 4 and the hydrogen permeable membrane 5 are attached to the attachment portion 3 via the seal member 6. The power generation unit may be an embodiment in which the casing as shown in FIG. 10 is isolated by the anode layer, the electrolyte layer, and the cathode layer. Instead of the casing, a cylindrical body is provided, and the anode layer, the electrolyte layer, It may be an embodiment in which the cathode layer is isolated. The fuel cell 11 shown in FIG. 10 operates as follows. First, the hydrogen gas separated by the hydrogen separation unit 2 is supplied to the anode layer 13 side of the power generation unit 15 by the hydrogen gas deriving unit 8 appropriately provided with a ventilator or the like. Next, in the cathode gas introduction unit 16, for example, a cathode gas such as air is supplied to the cathode layer 17 side of the power generation unit 15. Next, the power generation unit 15 to which the hydrogen gas and the cathode gas are supplied can take out the power with the connected circuit.

  In the hydrogen separator obtained by the method for manufacturing a hydrogen separator of the present invention, a gas leak test was performed. Examples and comparative examples of the gas leak test are shown below.

(Example)
Zirconia in which 60 parts by mass of nickel oxide and yttria 8 mol% are solid-dissolved (hereinafter, zirconia in which yttria is solid-dissolved may be referred to as “YSZ”; 40 parts by mass were mixed. Further, graphite powder was mixed as a pore forming agent to obtain a mixture. This mixture was extruded to form a bottomed cylindrical tube (which will be referred to as a porous support). After the bottomed cylindrical tube was sufficiently dried, it was degreased and fired at 1400 ° C. for 1 hour to obtain a porous support formed of NiO—YSZ cermet.

  The surface of the obtained porous support was observed with a stereo microscope (4 times magnification) manufactured by AS ONE Corporation. As a result of observation, a mark is given to a spot where a concave portion or a convex portion found on the surface of the porous support is found, and the marked spot is ground with Minita Co., Ltd. (abrasive material is diamond). did. After grinding, the surface of the porous support was again observed with the stereomicroscope to confirm the completion of removal of the concave or convex portions. The ground porous support was ultrasonically washed in ethanol and further dried at 120 ° C. for 3 hours.

  8YSZ and a binder were added to ethanol to prepare a slurry. The slurry was coated with a barrier layer on the outer surface of the ground porous support by dip coating. Thereafter, the barrier layer was baked by heat treatment. The thickness of the barrier layer was 20 μm.

  Next, a hydrogen permeable film was formed by an electroless plating method so as to cover the barrier layer. At this time, the opening of the porous support was sealed with a stopper and plated. In the electroless plating method performed here, the porous support coated with the barrier layer was first immersed in an aqueous hydrochloric acid solution of tin chloride dihydrate for 1 minute, washed, and then immersed in an aqueous hydrochloric acid solution of palladium chloride for 1 minute. The washing operation was repeated three times. Thereafter, the porous support was immersed in a plating solution containing ammonia water and a hydrazine aqueous solution at 50 ° C. under normal pressure to form the hydrogen permeable membrane 3 until the thickness became 1.5 μm. Thereafter, the inside of the porous support was depressurized in the same plating solution, and the hydrogen permeable membrane 3 was further thickened by 13.5 μm.

  The porous support coated with the hydrogen permeable membrane was subjected to reduction treatment at 600 ° C. for 3 hours in a hydrogen atmosphere to obtain a hydrogen separator. Next, an attachment fitting (a union fitting made by Swagelok Co., Ltd.) was attached to the obtained hydrogen separation part via a ferrule containing expanded graphite as a seal member, thereby obtaining a hydrogen separation device.

  The obtained hydrogen separator was first subjected to a gas leak test after allowing hydrogen to permeate continuously for 97 hours under conditions of an internal pressure of the porous support of 0.1 MPa, an external pressure of 0 MPa, and 600 ° C. In the gas leak test, helium gas was supplied to the inside of the hydrogen separator at a pressure of 0.3 MPa, and the amount of gas leak was measured with a soap flow meter manufactured by Horiba Estec Co., Ltd. connected to the outside of the hydrogen separator.

(Comparative example)
A hydrogen separator was prepared and a gas leak test was conducted in the same manner as in the example except that the barrier layer was coated without removing the concave or convex portions on the surface of the porous support.

  The results of Examples and Comparative Examples are shown in Table 1.

  In the example, in order to confirm reproducibility, a gas leak test was performed using a hydrogen separator manufactured under the same conditions as in the example. The amount of gas leak was 0 cc / min.

  Therefore, the hydrogen separator obtained by the method for producing a hydrogen separator according to the present invention has a recess, a bulge, or a hole in the hydrogen permeable membrane by removing the concave or convex portions in advance before coating the hydrogen permeable membrane. Etc., and leakage of gases other than hydrogen gas can be prevented.

FIG. 1 is a cross-sectional view showing a recess of a porous support and a hydrogen permeable membrane. FIG. 2 is a cross-sectional view showing the convex portion of the porous support and the hydrogen permeable membrane. FIG. 3 is a cross-sectional view showing a state where the concave portion of the porous support is ground. FIG. 4 is a cross-sectional view showing a state where the convex portion of the porous support is ground. FIG. 5 is a cross-sectional view showing an embodiment of a hydrogen separator obtained by the method for manufacturing a hydrogen separator of the present invention. FIG. 6 is a sectional view showing another embodiment of the hydrogen separator obtained by the method for manufacturing a hydrogen separator of the present invention. FIG. 7 is a cross-sectional view showing another embodiment of the hydrogen separator obtained by the method for manufacturing a hydrogen separator of the present invention. FIG. 8 is a cross-sectional view showing one embodiment of a fuel cell equipped with the hydrogen separator of the present invention. FIG. 9 is a cross-sectional view showing another embodiment of a fuel cell equipped with the hydrogen separator of the present invention. FIG. 10 is a cross-sectional view showing another embodiment of a fuel cell equipped with the hydrogen separator of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrogen separator 2 Hydrogen separation part 3 Attachment part 4 Porous support body 5 Hydrogen permeable membrane 6 Seal member 7 Raw material gas introduction part 8 Hydrogen gas extraction part 9 Residual gas extraction part 10 Frame 11 Fuel cell 12 Electrolyte layer 13 Cathode layer 14 connection terminal 15 power generation part 16 cathode gas introduction part 17 anode layer

Claims (7)

A cylindrical support having both ends or one end open, or a porous support having a plate shape;
A hydrogen permeable membrane that covers the surface of the porous support and allows hydrogen to selectively permeate;
A method for producing a hydrogen separator, comprising: forming a smooth recess by grinding a recess having a corner, which is present on a surface of the porous support covered by the hydrogen permeable membrane. A cylindrical support having both ends or one end open, or a porous support having a plate shape;
A hydrogen permeable membrane that covers the surface of the porous support and allows hydrogen to selectively permeate;
A method for producing a hydrogen separator, comprising: removing a convex portion having a corner portion present on a surface of the porous support covered by the hydrogen permeable membrane by grinding.   The method for producing a hydrogen separator according to claim 1 or 2, wherein a surface of the porous support is covered with a barrier layer, and a surface of the barrier layer is covered with a hydrogen permeable membrane.   The hydrogen separator according to any one of claims 1 to 3, wherein the porous support contains a reforming catalyst that generates hydrogen gas by reforming a supplied gas. Manufacturing method.   5. The method for manufacturing a hydrogen separator according to claim 1, wherein a part or all of the hydrogen permeable membrane is palladium or an alloy containing palladium. 6.   A hydrogen separator obtained from the method for producing a hydrogen separator according to any one of claims 1 to 5 and an electric power generation unit capable of taking out electric power using hydrogen as a fuel are integrally provided. Fuel cell.   A hydrogen separator obtained from the method for manufacturing a hydrogen separator according to any one of claims 1 to 5 and a power generation unit capable of taking out power using hydrogen as a fuel are separately provided. A fuel cell comprising.

Images