JP2006332027A - Reformer-integrated fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reformer-integrated fuel cell which, by constructing a conventional steam reformer, a hydrogen purifier, and a fuel cell integrally in one body, is made remarkably compact in device structure and capable of cost reduction with high practicality and capable of improving power generating efficiency and durability. <P>SOLUTION: This is a reformer-integrated fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation plus anode layer, an electrolyte layer, and a cathode layer are formed in order on a porous reforming catalyst layer. This reformer-integrated fuel cell is constructed as a reformer-integrated fuel cell having various shapes such as a cross-section circular shape, a cross-section rectangular shape, a cross-section polygonal shape, and a flat plate shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reformer-integrated fuel cell, and more specifically to a reformer-integrated fuel cell in which a fuel reformer and a fuel cell are integrated.

  Fuel cells include solid polymer fuel cells (PEFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxides, depending on the material used for the ionic conductor, or electrolyte. There are various types such as a physical fuel cell (SOFC), but these are the same in principle. As the electrolyte, solid polymer is used in PEFC, molten carbonate is used in MCFC, and phosphoric acid is used in PAFC.

  The fuel of PEFC and PAFC is hydrogen. Although the fuel of MCFC is hydrogen, since carbon monoxide generates hydrogen by the shift reaction at the anode of MCFC, carbon monoxide is also used as fuel in MCFC. The fuel of SOFC is hydrogen, carbon monoxide and methane, and methane is reformed to hydrogen and carbon monoxide by the metal (Ni etc.) of the anode of SOFC to become fuel.

  The following description will be given mainly using SOFC as an example, but the same applies to other fuel cells. The operating temperature of SOFC is in the range of 800 to 1000 ° C., usually as high as 1000 ° C., but a supporting membrane type SOFC having an operating temperature of about 650 to 800 ° C., for example, about 750 ° C. is being developed. The SOFC is composed of a three-layer unit of an anode and a cathode with a solid oxide electrolyte in between.

Oxygen in the air introduced into the cathode becomes oxide ions (O ²⁻ ) at the cathode, and reaches the anode through the solid oxide electrolyte. Here, it reacts with the fuel introduced into the anode and emits electrons to produce a reaction product such as electricity and water. Used air at the cathode is discharged as cathode offgas, and spent fuel at the anode is discharged as anode offgas. The anode offgas contains reaction products such as unused fuel, water vapor, and carbon dioxide at the anode. include.

  Hydrogen and carbon monoxide, which are SOFC fuels, can be obtained by steam reforming of hydrocarbons or reforming by partial oxidation. FIG. 18 is a diagram schematically showing a steam reformer. It is generally composed of a combustion section in which a burner or a combustion catalyst is arranged and a reforming section in which a reforming catalyst is arranged. In the reforming section, the hydrocarbon reacts with the steam to generate a hydrogen-rich reformed gas. Since the reaction occurring in the reforming part involves a large endotherm, it is necessary to supply heat from the outside in order for the reaction to proceed. For this reason, the combustion heat (ΔH) generated by the combustion of the fuel gas by the air in the combustion section is supplied to the reforming section.

  In general, when the reformed gas obtained by reforming hydrocarbons is supplied to the fuel cell as pure hydrogen, it is necessary to install a hydrogen purifier after the reformer as shown in FIG. Even if the gas passes through the hydrogen purifier, it is still at a high temperature. For example, in order to use it as a fuel for PEFC, it is necessary to cool it to 100 ° C. or less with a heat exchanger. Instead of installing the reformer and the hydrogen purifier separately as described above, the membrane is formed as an integrated device so that the reformer can generate the reformed gas and purify the reformed gas with a single device. There is a reactor. FIG. 20 schematically shows a membrane reactor.

  Hydrocarbons are reformed in the reforming catalyst layer by the reforming reaction with steam using the heat generated in the burner as a heating source to become reformed gas. Hydrogen in the reformed gas is selectively separated and extracted by a hydrogen permeable membrane such as a Pd membrane. Since the hydrogen thus obtained has high purity, it is used as it is as fuel for the fuel cell as shown in FIG.

  However, in the case of a membrane reactor, the use of high-purity hydrogen as a fuel for a fuel cell still requires that a fuel cell be separately installed at the subsequent stage. Further, since the high purity hydrogen from the membrane reactor is at a high temperature, it is necessary to supply it after cooling it to 100 ° C. or less with a heat exchanger, for example, as a fuel for PEFC as in the case of the steam reformer.

  By the way, Japanese Patent Application Laid-Open No. 2004-146337 discloses a fuel cell having a hydrogen purification function of reformed gas. FIG. 21 is a cross-sectional view disclosed in the publication. The electrolyte membrane 40 is sandwiched between the oxygen electrode 10 and the hydrogen electrode 30, and the electrolyte membrane 40 has a five-layer structure centered on a dense substrate 43 formed of vanadium (V). Thin films of electrolyte layers 42 and 44 made of solid oxide are formed on both surfaces of the substrate 43, and palladium (Pd) coatings 41 and 45 are provided on the outer surfaces of the electrolyte layers 42 and 44.

  The palladium coatings 41 and 45 correspond to hydrogen permeable materials, but since hydrogen-rich fuel gas is supplied to the hydrogen electrode 30, there is no explicit description in the publication, but hydrocarbons are separately used as fuel. Fuel reformed by a fuel reformer or the like is used. The base material 43 also serves as a support for the electrolyte layers 42 and 44 together with the Pd coating. Since the base material 43 is dense, the electrolyte layers 42 and 44 are considerably thinned (about 1 μm or less). Is possible.

  Japanese Patent Application Laid-Open No. 2005-19041 discloses a battery in which a solid electrolyte layer is sandwiched between an anode and a cathode. The anode is formed by a hydrogen permeable electrode in which a hydrogen permeable metal film is bonded to a porous substrate. In addition, a battery is described in which the solid electrolyte layer is made of a proton conductive oxide thin film. However, in the case of this battery as well, as in the fuel cell disclosed in Japanese Patent Application Laid-Open No. 2004-146337, a fuel obtained by reforming hydrocarbons separately using a fuel reformer or the like is used as the fuel supplied from the porous substrate side.

JP 2004-146337 A JP-A-2005-19041

  In the present invention, the fuel reformer and the fuel cell are not separately disposed as in the conventional case, and the fuel reformer is not disposed separately from the fuel reformer, the hydrogen purifier, and the fuel cell. It is an object of the present invention to provide a reformer-integrated fuel cell in which the device configuration is remarkably compact and the cost can be reduced by integrally configuring the reactor, the hydrogen purifier, and the fuel cell.

  The present invention is (1) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer are sequentially formed on the porous reforming catalyst layer. A reformer-integrated fuel cell characterized by being arranged is provided.

  The present invention is (2) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen layer are sequentially formed on a porous reforming catalyst layer having a circular cross section having a fuel flow path therein. A reformer-integrated fuel cell comprising a separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (3) a fuel cell in which a fuel reformer and a fuel cell are integrated, wherein a barrier layer, a hydrogen layer are sequentially formed on a porous reforming catalyst layer having an elliptical cross section having a fuel flow path therein. A reformer-integrated fuel cell comprising a separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (4) a fuel cell in which a fuel reformer and a fuel cell are integrated, wherein a barrier layer, a hydrogen layer are sequentially formed on a porous reforming catalyst layer having a rectangular cross section having a fuel flow path therein. A reformer-integrated fuel cell comprising a separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (5) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen layer are sequentially formed on a porous reforming catalyst layer having a polygonal cross section having a fuel flow path therein. A reformer-integrated fuel cell comprising a separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (6) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer is sequentially formed on an inner peripheral surface of a porous reforming catalyst layer having a circular cross section having an air flow path therein. A reformer-integrated fuel cell comprising a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (7) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer is sequentially formed on the inner peripheral surface of a porous reforming catalyst layer having an elliptical cross section having an air flow path therein. A reformer-integrated fuel cell comprising a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (8) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer is sequentially formed on the inner peripheral surface of a porous reforming catalyst layer having a rectangular cross section having an air flow path therein. A reformer-integrated fuel cell comprising a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (9) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer is sequentially formed on an inner peripheral surface of a porous reforming catalyst layer having a polygonal cross section having an air flow path therein. A reformer-integrated fuel cell comprising a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer is provided.

  The present invention is (10) a fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, an electrolyte layer, and an electrolyte layer are sequentially formed on a flat porous reforming catalyst layer. Provided is a reformer-integrated fuel cell comprising a cathode layer.

  The present invention is (11) a fuel cell in which a fuel reformer and a fuel cell are integrated, wherein a porous reforming catalyst layer is formed on an electrically insulating porous substrate tube having a fuel flow path therein, A plurality of power generation element portions having a layer structure in which a barrier layer, a hydrogen separation / anode layer, an electrolyte, and a cathode layer are sequentially stacked are formed adjacent to each other, and at least one adjacent power generation element portion is electrically connected by an interconnector. A reformer-integrated fuel cell is provided which is connected in series.

  The present invention provides (12) a reformer-integrated fuel cell, wherein the electrically insulating porous substrate tube has a hollow plate shape.

  The present invention provides (13) the reformer-integrated fuel cell according to claim 11, wherein the electrically insulating porous substrate tube has a hollow cylindrical shape.

  As described above, in the prior art, the fuel reformer and the fuel cell were arranged separately. However, according to the present invention, the fuel reformer, the hydrogen purifier, and the fuel cell are integrated, so that the fuel cell is formed. It can be made much more compact. As a result, the startup time can be shortened, and it can be used as a power generator for mobile objects such as automobiles and ships, a power generator installed in a home or factory, or a power generator that is easy to carry. For example, it is very useful in practice. In addition, the reformer-integrated fuel cell of the present invention can improve the power generation efficiency and durability of the fuel cell because it reforms hydrocarbons and uses hydrogen as fuel.

  The present invention is a fuel cell in which a fuel reformer, a hydrogen purifier, and a fuel cell are integrated. A barrier layer, a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer are sequentially disposed on the porous reforming catalyst layer. The reforming catalyst layer may have a cylindrical shape, that is, a circular cross section, an elliptical cross section, a rectangular cross section, a polygonal cross section, or a flat plate shape. Also good. In any case of the reforming catalyst layer in any shape, the barrier layer, the hydrogen separation / anode layer, the electrolyte layer, and the cathode layer are sequentially arranged on the reforming catalyst layer. The integrated fuel cell is configured in a shape corresponding to the reforming catalyst layer.

  When the reforming catalyst layer has a circular cross section, an elliptical cross section, a rectangular cross section, or a polygonal cross section, a fuel flow path is provided inside. When the reforming catalyst layer is a flat plate, the side opposite to the side where the barrier layer, the hydrogen separation / anode layer, the electrolyte layer, and the cathode layer are disposed is the fuel flow path. The reformer-integrated fuel cell of the present invention can be operated at a temperature of 400 to 700 ° C, preferably 550 to 650 ° C. This temperature is equivalent to the steam reforming temperature of the hydrocarbon fuel in the porous reforming catalyst layer.

  Hereinafter, the reformer-integrated fuel cell of the present invention will be sequentially described with reference to the drawings as appropriate. FIG. 1 is a diagram for explaining the basic configuration of the present invention. In FIG. 1, reference numeral 1 denotes a porous reforming catalyst layer, which is a first layer constituting a reformer-integrated fuel cell. Reference numeral 2 denotes a barrier layer, which is a second layer constituting the reformer-integrated fuel cell. Reference numeral 3 denotes a hydrogen separation / anode layer, which is a third layer constituting the reformer-integrated fuel cell. Reference numeral 4 denotes an electrolyte layer, which is a fourth layer constituting the reformer-integrated fuel cell. Reference numeral 5 denotes a cathode layer, which is a fifth layer constituting the reformer-integrated fuel cell.

<Porous catalyst layer as first layer>
The porous catalyst layer, which is the first layer, is a layer that functions not only as a reforming catalyst but also as a support base for a fuel cell. Further, when (Ln _1−x A _x ) _y MO _{3 ± δ} described later is included in the second layer, the current generated in the third layer also serves as a current extraction through the second layer. The porous reforming catalyst layer preferably has communication holes, a porosity of 10 to 85%, and an average pore diameter of 0.05 to 10 μm. The thickness depends on the strength required for the support substrate, but is preferably 100 μm or more. In the porous reforming catalyst layer, reformed gas is generated by steam reforming of the hydrocarbon fuel.

The reformed gas contains H ₂ , CO, and CO ₂ , but only H ₂ flows to the electrolyte layer through the hydrogen separation / anode layer, which will be described later, and contributes to power generation. The reforming catalyst layer only needs to have a reforming catalyst function when the reformer-integrated fuel cell is used, and does not necessarily have to have a reforming catalyst function when the reforming catalyst layer is formed. The fact that only H ₂ flows through the hydrogen separation / anode layer to the electrolyte layer and contributes to power generation is an important feature in the reformer-integrated fuel cell of the present invention. When using reformed gas as fuel, it is different from SOFC which also uses CO as fuel.

As a constituent material of the porous reforming catalyst layer, a sintered body of a mixture of nickel and yttria stabilized zirconia, a sintered body mainly composed of a mixture of nickel and yttria stabilized zirconia (Ni-YSZ cermet, etc.), etc. Examples thereof include porous ceramics and porous cermets that have both a function as a supporting substrate and a function as a reforming catalyst. In the case of Ni-YSZ cermet, for example, Ni particles, NiO particles and YSZ (= yttria-stabilized zirconia) particles are mixed, the mixture is formed by extrusion molding, pressure molding or the like and sintered. By reducing this in a reducing atmosphere, a reduced product of the sintered body is obtained. As an example, a reduced product obtained by reducing a sintered body having a material composition of NiO: 8YSZ = 60: 40 (weight ratio) in hydrogen at 800 ° C. for 3 hours (porosity 40%, gas permeability 100 cc / min / cm ² / atm, 4-point bending strength 85 MPa), reforming temperature = 600 ° C., S / C ratio = 3.0, reforming pressure 0.8 MPa, and a methane conversion rate of about 39% as a single catalyst, The reforming performance is almost the same as that of a conventional granular reforming catalyst.

<Barrier layer as the second layer>
The barrier layer, which is the second layer, is a layer for preventing mutual diffusion of Ni of the reforming catalyst layer and Pd of the hydrogen separation membrane component. The constituent material must not be decomposed into metal by reduction in a hydrogen atmosphere of 400 to 700 ° C., which is the use temperature. When the metal is decomposed by reduction, it reacts with the third layer, the hydrogen separation / anode layer composed of the Pd film or Pd alloy film, and a hole is formed in the hydrogen separation / anode layer. Decrease occurs, which is not preferable. It is also necessary not to decompose in a carbon dioxide atmosphere at the use temperature. Carbon dioxide is generated as a by-product when the hydrocarbon-based fuel is reformed in the reforming catalyst layer. Decomposing with carbon dioxide is not preferable because the barrier layer may cause a decrease in strength.

The materials include stabilized zirconia, partially stabilized zirconia, zirconia, alumina, magnesia, (Ln _{1 -x} A _x ) _y MO _{3 ± δ} (where Ln is a rare earth element, A is Ba, Sr or Ca, M is Cr or Ti, the range of x is 0 ≦ x ≦ 1, and the range of y is 0.9 ≦ y ≦ 1.1.), Or a mixture of these materials, or a compound of these materials Can be mentioned. These materials are durable in reducing and carbon dioxide atmospheres. Further, the barrier layer needs to be porous in order for gas to pass through, and the porosity is preferably 5 to 85% and the average pore diameter is preferably 0.05 to 10 μm. The thickness is preferably 5 to 100 μm. The reason why “± δ” is used for the O component in these equations is that these materials may deviate from the law of multiple proportionality. The same applies to “± δ” in the following expression.

  Here, the present inventors have previously developed a hydrogen production apparatus using a “reforming catalyst / support” as a support for the hydrogen permeable membrane (Japanese Patent Laid-Open No. 2004-149332, hereinafter referred to as “332”). )), A reaction cylinder and a reaction plate for a hydrogen production apparatus in which the reforming catalyst / support is further improved (Japanese Patent Application No. 2004-133906, hereinafter referred to as “No. 906 application”). FIG. 2 is a view showing an outer membrane type cylindrical reaction tube in which the “reforming catalyst / support” disclosed in Japanese Patent No. 332 is formed in a cylindrical shape. As shown in FIG. 2, the surface of the reforming catalyst / support layer and the hydrogen permeable membrane are integrated with each other, whereby the hydrocarbon gas can be effectively reformed and high-purity hydrogen can be produced.

JP 2004-149332 A Japanese Patent Application No. 2004-133906

  However, it has been found that there is room for further improvement in the hydrogen production reactor incorporating the “reforming catalyst / support” constructed as described above. That is, the unused hydrogen production reaction cylinder had a clear boundary between the reforming catalyst / support layer and the hydrogen permeable membrane layer, but the hydrogen production reaction cylinder after a long period of use (for example, 1000 hours). Then, it was found that the metal (Ni) component of the reforming catalyst / support and the Pd of the hydrogen permeable membrane are complicated, that is, diffusion is a cause of impairing the hydrogen permeable performance of the hydrogen permeable membrane. The reforming catalyst / support layer corresponds to the aforementioned <first porous catalyst layer>, and the hydrogen permeable membrane layer corresponds to the <third hydrogen separation / anode layer> described later. is doing.

  Therefore, in the 906 application, in order to prevent such diffusion, by providing a barrier layer between the reforming catalyst / support and the hydrogen permeable membrane, the reforming catalyst / support and the hydrogen permeable membrane are separated. It solves the problem of degradation of hydrogen permeation performance due to interdiffusion of components between them. That is, as shown in FIG. 3, a barrier layer is provided on the surface of the substrate, that is, the reforming catalyst / support, and a hydrogen permeable membrane is disposed thereon. Thereby, mutual diffusion between the component of the reforming catalyst / support and the component of the hydrogen permeable membrane can be prevented.

  In this invention, the concept of the said barrier layer in 906 application is applied as a barrier layer which is a 2nd layer. The barrier layer needs to be porous, but may be porous when formed, or may be porous when used as a fuel cell. Further, when the barrier layer is provided in such a manner, as shown in FIG. 3, the hydrogen separation and anode layer, which is the third layer, is caused to penetrate into the barrier layer, so that the first layer has a so-called hook effect. With respect to a certain porous reforming catalyst, the hydrogen separation and anode layer can be kept stronger. In addition, the barrier layer has an effect of three-dimensionally expanding the hydrogen-dissolved sites from the fuel gas phase to the anode phase, whereby the anode polarization of the fuel cell according to the present invention can be reduced.

When (Ln _1−x A _x ) _y MO _{3 ± δ} is included in the barrier layer, the (Ln _1−x A _x ) _y MO _{3 ± δ} has electric conductivity, and thus is generated at the anode. The electric current can be taken out to the reforming catalyst / support layer, and the reaction occurring at the anode can be rapidly advanced.

  The barrier layer can be formed by a dip coating method, a spray spraying method, a printing method, or a catalyst metal dissolution and removal method on the porous reforming catalyst layer. Among these, the printing method is particularly useful when the porous reforming catalyst layer is a flat plate type.

<Third layer, hydrogen separation and anode layer>
The third hydrogen separation / anode layer is formed on the surface of the barrier layer formed on the porous reforming catalyst layer. The hydrogen separation / anode layer has a function and a role as an anode in addition to a function and a role as a hydrogen separation membrane. As a constituent material of the hydrogen separation / anode layer, any material can be used as long as it has a function of selectively permeating hydrogen from the reformed gas and a function as an anode of the fuel cell. Preferred examples thereof include a Pd film, a Pd alloy film, a Group 5 metal (V, Nb or Ta) film, a Group 5 metal alloy film, a Group 5 metal film or a Group 5 metal alloy film and a Pd film or a Pd alloy film. The multilayer film is mentioned. Examples of the metal alloyed with Pd include Au, Ag, Cu, Pt, Rh, Ru, Ir, Ce, Sm, Tb, Dy, Ho, Er, Yb, Y, and Gd. Two or more of these metals may be combined.

  These metal films and alloy films are supported on the porous reforming catalyst layer by a plating method, a vapor deposition method, and other appropriate methods through a barrier layer. The hydrogen separation membrane / anode layer needs to be a dense membrane without holes, and the thickness is preferably 30 μm or less. These metal films are supported on the surface of the barrier layer by a plating method, a vapor deposition method, or other appropriate methods. As described above, since the barrier layer is interposed, the hydrogen separation / anode layer itself can be thinned. Pd and Pd alloys are expensive, but the cost can be reduced by reducing the thickness, and the hydrogen permeation rate can be improved.

<The electrolyte layer which is the 4th layer>
The electrolyte layer, which is the fourth layer, plays a role of conducting and passing hydrogen ions (protons) ionized at the anode by hydrogen as the fuel. As the constituent material, any material can be used as long as it can conduct protons. Examples thereof include perovskite compounds represented by the formula: ABO ₃ . In the formula, A is Ba, Sr or Ca, and B is Ce or Zr. Among these, Ce and Zr at the B site can be partially substituted with rare earth elements such as Y and Yb. The thickness of the electrolyte layer, that is, the proton conductive electrolyte is preferably 10 μm or less. The electrolyte layer only needs to be composed of a material capable of conducting protons as a main component, and may be a mixture with other materials within a range having proton conductivity. It is known that some of these electrolyte materials, particularly compounds containing Ce at the B site, have poor chemical stability against CO ₂ in the fuel gas, but the third layer is a hydrogen separation and anode layer. If is formed densely, the direct contact between the electrolyte material and the fuel gas layer is interrupted, so that such a problem can be avoided.

<Cathode layer as the fifth layer>
The material of the fifth layer or the cathode layer is a fifth layer _{La 0. 6 Sr 0. 4} CoO 3 ± δ, Sm 0. 5 Sr 0. 5 CoO 3 ± δ, Pr 0. 5 Ba 0 . ₅ CoO ₃ in _± Ln _1-x, such as _{δ a} x CoO _{3 ± δ} or _{Ln 1-x a x FeO 3} ± δ, Ln 1-x a x MnO 3 ± δ ( these formulas, Ln represents a rare earth element , A is Ba, Sr, or Ca) and metals such as Ag, Pt, and Ph. The thickness is preferably 30 μm or less.

  As described above, the reformer integrated fuel cell of the present invention is configured in various shapes such as a circular cross section, an elliptical cross section, a rectangular cross section, a polygonal cross section, and a flat plate shape. In any case of the reforming catalyst layer of any shape, the barrier layer, the hydrogen separation / anode layer, the electrolyte layer, and the cathode layer are sequentially arranged on the reforming catalyst layer. The fuel cell is configured in a shape corresponding to the reforming catalyst layer or in the shape of an electrically insulating porous substrate tube.

<Cylindrical fuel cell with integrated fuel reformer and fuel cell>
FIG. 4 is a diagram illustrating a cylindrical reformer-integrated fuel cell. FIG. 4A is a longitudinal sectional view. 4B is a view of FIG. 4A viewed from the left side (FIG. 4A is a cross-sectional view, but is a view viewed from the left side as a whole). 4C is a cross-sectional view taken along line AA in FIG. 4A [FIG. 4A is a cross-sectional view, but is a cross-sectional view as a whole]. 4B to 4C are enlarged from FIG. 4A. Each of the layers 1 to 5 in FIG. 4 corresponds to each of the layers 1 to 5 in FIG. 1, and this also applies to the reformer-integrated fuel cell described below.

  The porous reforming catalyst layer 1 is formed in a cylindrical shape (circular cross section) having an inner space (lumen) S communicating from one end to the other end. The inner space S is a flow path for fuel and water vapor, that is, a fuel flow path. When the constituent material of the porous reforming catalyst layer 1 is Ni-YSZ cermet, for example, Ni particles, NiO particles and YSZ particles are mixed, formed by extruding the mixture into a cylindrical shape, and prepared by sintering. Is done. In the sintering, the barrier layer 2, the hydrogen separation / anode layer 3, and the electrolyte layer 4 are sequentially applied to the porous sintered layer (= porous reforming catalyst layer) 1 and then sintered together. You may tie it.

  The barrier layer 2 is formed, for example, by dispersing zirconia powder in water or an organic solvent to form a slurry, coating the outer surface of the porous reforming catalyst layer 1 by a spraying method, a printing method, or the like, and performing a heat treatment. Can do. The hydrogen separation and anode layer 3 is formed on the surface of the barrier layer 2 by the aforementioned Pd film, Pd alloy film, Group 5 metal film, Group 5 metal alloy film, Group 5 metal film or Group 5 metal alloy film and Pd film or Pd. The barrier film 2 is supported by forming a multilayer film with the alloy film by plating or vapor deposition.

  Here, the hydrogen separation / anode layer 3 can be formed as a current extraction terminal by thickening the layer at one end thereof as indicated by 3 'in FIG. The layer thickness portion 3 ′ may be integrally formed of the same material as the hydrogen separation / anode layer 3, or may be separately formed of the same material or a conductive material as the hydrogen separation / anode layer 3. Further, by increasing the thickness of one end of the hydrogen separation / anode layer 3 as 3 ', the permeated hydrogen is selectively sent to the electrolyte layer 4, thereby preventing hydrogen leakage from the current terminal portion. it can.

For example, when La _0.8 Ca _0.2 CrO _{3 ± δ} is used for the barrier layer 2, La _0.8 Ca _0.2 CrO _{3 ± δ} is electrically conductive, and the porous reforming catalyst layer 1 also contains nickel. Therefore, electricity generated in the hydrogen separation / anode layer 3 flows to the porous reforming catalyst layer 1 through the barrier layer 2. Electricity can be taken out by bringing a current collector into contact with the porous reforming catalyst layer 1. These points are the same for the embodiments described below.

The electrolyte layer 4 is a perovskite compound represented by ABO ₃ having proton conductivity (wherein, A is Ba, Sr or Ca, B is Ce or Zr, of which Ce and Zr at the B site are partly Y, can be replaced by a rare earth element such as Yb.), for _{example, BaCe 0. 8 Y 0.} 2 O 3 ± δ water or organic solvents such as, a binder, adding a dispersing agent and mixed to form a slurry, screen printing It can be formed by applying heat treatment to the surface of the hydrogen separation / anode layer 3 by heat treatment. Alternatively, it may be formed by a so-called sol-gel method, physical vapor deposition, or chemical vapor deposition using an alkoxide solution containing each metal ion of BaCe _0.8 Y _0.2 O _{3 ± δ} .

The cathode layer 5 has Ln _1-x AE _x CoO _{3 ± δ} or Ln such as La _0.6 Sr _0.4 CoO _{3 ± δ} , Sm _0.5 Sr _0.5 CoO _{3 ± δ} , Pr _0.5 Ba _0.5 CoO _{3 ± δ on} the surface of the electrolyte layer 4. Ceramics such as _1-x AE _x FeO _{3 ± δ} , Ln _1-x AE _x MnO _{3 ± δ} (where Ln represents a rare earth element and AE represents an alkaline earth metal), Ag, Pt, Ph It is formed by applying a heat treatment after applying it by screen printing or the like using a metal slurry or paste.

  FIGS. 5A and 5B are perspective views of the cylindrical fuel cell configured as described above. FIG. 5B is an enlarged view of FIG. 5A and shows the positional relationship between the internal layers by dotted lines. As shown in FIG. 5A, when used as a fuel cell, fuel and water vapor flow from one end of the fuel flow path S in the porous reforming catalyst layer 1 toward the other end, and an oxidant is provided on the cathode layer 5 side. A gas, for example air, is circulated. A closed circuit is formed between the hydrogen separation / anode layer 3 and the cathode layer 5, and power is taken out by applying a load. When lanthanum chromite is used for the barrier layer 2, a closed circuit can be formed between the porous reforming catalyst layer 1 and the cathode layer 5.

<Aspects of an elliptical cross section fuel cell in which a fuel reformer and a fuel cell are integrated>
FIG. 6 is a diagram illustrating a reformer-integrated fuel cell having an elliptical cross section. As shown in FIG. 6, a barrier layer 2, a hydrogen separation / anode layer 3, an electrolyte layer 4, and a cathode layer 5 are sequentially arranged on the outer surface of a porous reforming catalyst layer 1 having an elliptical cross section having a fuel flow path S therein. . The other points are the same as those in the above-described <cylindrical fuel cell embodiment in which a fuel reformer and a fuel cell are integrated>.

<Aspects of a fuel cell having a rectangular cross section in which a fuel reformer and a fuel cell are integrated>
FIG. 7 is a diagram illustrating a reformer-integrated fuel cell having a rectangular cross section. As shown in FIG. 7A, the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially formed on the outer surface of the porous reforming catalyst layer 1 having a rectangular cross section having the fuel flow path S therein. It is the state that arranged. FIG. 7B shows a state in which the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially disposed on the upper and lower surfaces of the porous reforming catalyst layer 1 having a rectangular cross section. . The other points are the same as those in the above-described <cylindrical fuel cell embodiment in which a fuel reformer and a fuel cell are integrated>. In these embodiments, a plurality of fuel flow paths S may be provided as shown in FIG.

  FIG. 8 is a perspective view showing a reformer-integrated fuel cell corresponding to FIG. 7B among the reformer-integrated fuel cells having a rectangular cross section configured as described above. As shown in FIG. 8, when used as a fuel cell, fuel and water vapor flow from one end to the other end of the fuel flow path S in the porous reforming catalyst layer 1, and an oxidant gas, for example, on the cathode layer 5 side, for example. Allow air to circulate. A closed circuit is formed between the porous reforming catalyst layer 1 or the hydrogen separation / anode layer 3 and the cathode layer 5, and electric power is taken out by applying a load.

<Aspects of a fuel cell having a square cross section in which a fuel reformer and a fuel cell are integrated>
FIG. 9 is a diagram illustrating a reformer-integrated fuel cell having a square cross section. As shown in FIG. 9 (a), the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially formed on the outer surface of the porous reforming catalyst layer 1 having a square cross section having the fuel flow path S therein. It is the state that arranged. FIG. 9B shows a state in which the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially arranged on the upper, lower, left, and right surfaces of the porous reforming catalyst layer 1 having a rectangular cross section. . The other points are the same as those in the above-described <cylindrical fuel cell embodiment in which a fuel reformer and a fuel cell are integrated>. A reformer-integrated fuel cell having a polygonal cross-section other than the reformer-integrated fuel cell having a quadrangular cross-section is similarly configured.

<Inner membrane cylindrical fuel cell with integrated fuel reformer and fuel cell>
FIG. 10 is a view for explaining a reformer-integrated fuel cell having a circular cross section having an air passage SA therein. As shown in FIG. 10, a barrier layer 2, a hydrogen separation / anode layer 3, an electrolyte layer 4, and a cathode layer 5 are sequentially arranged on the inner peripheral surface of the porous reforming catalyst layer 1 having a circular cross section. The air channel SA is provided in the state. The other points are the same as those in the above-described <cylindrical fuel cell embodiment in which a fuel reformer and a fuel cell are integrated>. The inner membrane cross section elliptical fuel cell other than the inner membrane cross section fuel cell, the inner membrane cross section rectangular fuel cell, and the inner membrane cross section fuel cell are configured in the same manner.

<Mode of a flat plate fuel cell in which a fuel reformer and a fuel cell are integrated>
The reformer-integrated fuel cell according to the present invention can also be configured as a planar reformer-integrated fuel cell. FIG. 11 is a diagram illustrating a flat reformer-integrated fuel cell. 11A is a plan view, FIG. 11B is a cross-sectional view taken along the line AA in FIG. 11A, and FIG. 11C is a cross-sectional view taken along the line BB in FIG. The constituent materials of each layer and the formation process are the same as those in the above-described <cylindrical fuel cell embodiment in which a fuel reformer and a fuel cell are integrated>. Also in the planar reformer-integrated fuel cell, a closed circuit is formed between the porous reforming catalyst layer 1 or the hydrogen separation / anode layer 3 and the cathode layer 5, and electric power is taken out by applying a load.

<Lamination Mode 1 of Flat Fuel Cell Integrated with Fuel Reformer and Fuel Cell>
The planar reformer-integrated fuel cell according to the present invention can be stacked by arranging a plurality of them, and FIG. 12 is a diagram for explaining the mode. As shown in FIG. 12, a plurality of planar fuel cells are alternately arranged with their anode layers and cathode layers facing each other and spaced apart. As a result, the anode layer of adjacent flat reformer-integrated fuel cells faces the same gap, and the cathode layer of adjacent flat reformer-integrated fuel cells faces the same gap. The body fuel cell stack can be made compact. When used as a fuel cell, fuel and water vapor flow in the gap between adjacent anode layers, and an oxidant gas, for example, air, flows between adjacent cathode layers, so that the porous reforming catalyst layer 1 or the hydrogen separation / cumulative layer is used. A closed circuit is formed between the anode layer 3 and the cathode layer 5, and electric power is taken out by applying a load.

<Lamination mode 2 of flat plate fuel cell in which fuel reformer and fuel cell are integrated>
When the second layer includes (Ln _1−x A _x ) _y MO _{3 ± δ} , the flat plate reformer-integrated fuel cell is stacked using the separator SE and stacked. You can also FIG. 13 is a diagram showing this aspect. As shown in FIG. 13, a plurality of planar reformer integrated fuel cells are arranged between the adjacent porous reforming catalyst layer 1 and the cathode layer 5 positioned vertically with the cathode layer 5 facing in the same direction. The separator SE is sandwiched and laminated. It can be made compact by stacking the flat reformer integrated fuel cells.

  Since the holes in the porous reforming catalyst layer are communication holes, fuel and water vapor are circulated in the lateral direction. As a constituent material of the separator, a heat resistant alloy such as stainless steel can be used. When used as a fuel cell, fuel and water vapor are introduced into the anode side and air is introduced into the cathode side from the lateral direction of the stacked stack, so that the outermost porous reforming catalyst layer 1a and the outermost layer in FIG. A closed circuit is formed between the outer cathode layer 5a and power is taken out by applying a load.

<Aspects of horizontally striped cross-section plate fuel cell in which fuel reformer and fuel cell are integrated>
FIG. 14 is a diagram for explaining a horizontally striped plate-shaped reformer-integrated fuel cell. 14A is a plan view, and FIGS. 14B to 14C are cross-sectional views taken along line AA in FIG. 14A. As shown in FIG. 14, the porous reforming catalyst layer 1, the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially arranged on the plate-like electrically insulating porous substrate SU. . Adjacent cells, that is, the porous catalyst layer 1 and the cathode layer 5 of the power generation element are electrically connected in series by the interconnector IN. In FIG. 14, the interconnector IN is arranged at the center in the width direction as shown in FIG. 14 (a). However, the present invention is not limited to this, and it is arranged at one side of the width in the width direction or at the entire width in the width direction. May be.

When used as a fuel cell, that is, during power generation, as shown in FIG. 14C, fuel and water vapor are circulated on the electrically insulating porous substrate SU side, and air is circulated on the cathode layer 5 side. The fuel and water vapor reach the porous reforming catalyst layer 1 through the pores of the porous substrate SU, where the fuel is steam reformed, and only H ₂ in the reformed gas passes through the hydrogen separation / anode layer 3 and the electrolyte. It flows to the layer 4 and contributes to power generation. In addition, in FIG.14 (c), the flow of the electric current at the time of electric power generation is shown.

  A reformer-integrated fuel cell having a horizontal stripe-shaped cross-sectional shape, a horizontal-stripe-shaped cross-sectional elliptical shape, a horizontal-stripe-shaped cross-sectional rectangular shape, and a horizontal-stripe-shaped cross-sectional polygonal shape is similarly configured. FIG. 15 is a diagram for explaining a reformer-integrated fuel cell having a horizontally striped rectangular cross section. 15A is a longitudinal sectional view, and FIG. 15B is a side view of FIG. 15A viewed from the right side, that is, a side view. As shown in FIG. 15, the porous reforming catalyst layer 1, the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially arranged on the surface of the electrically insulating porous substrate SU having a rectangular cross section. It is a mode. Adjacent cells, that is, the porous catalyst layer 1 and the cathode layer 5 of the power generation element are connected in series by an interconnector IN.

  Here, the embodiment in which the electrically insulating porous substrate is circular in cross section can be said to be “hollow cylindrical shape” because the inside is hollow and cylindrical. Further, regarding the aspect of the electrically insulating porous substrate having a rectangular cross section and a polygonal cross section, it can be said to be a “hollow plate shape” because the inside is hollow and each surface is plate shaped.

FIG. 16 is a diagram for explaining another reformer-integrated fuel cell having a horizontal stripe shape and a rectangular cross section when the second layer does not contain the aforementioned (Ln _1−x A _x ) _y MO _{3 ± δ} . is there. As shown in FIG. 16, the barrier layer 2, the hydrogen separation / anode layer 3, the electrolyte layer 4, and the cathode layer 5 are sequentially disposed on the porous reforming catalyst base 1 having a rectangular cross section having the fuel flow path S therein. is there. Hydrogen separation / anode layer 3 and cathode layer 5 of adjacent power generation elements are connected in series by interconnector IN. This embodiment corresponds to a reformer integrated fuel cell having a rectangular cross section as shown in FIG. A reformer-integrated fuel cell having a horizontal stripe-shaped circular cross section and a horizontal stripe-shaped polygonal cross-section is configured in the same manner.

  The reformer-integrated fuel cell of the present invention is used by being appropriately accommodated in a heat insulating container or the like. At that time, a fuel and water vapor supply mechanism to the porous reforming catalyst layer side, an anode off gas derivation mechanism, an oxidant gas supply mechanism to the cathode layer side, and a cathode off gas derivation mechanism are arranged. As the fuel to be supplied to the porous reforming catalyst layer, city gas, LP gas, natural gas, gasoline, kerosene, and other various hydrocarbon fuels can be used. In the case of a fuel containing a sulfur compound such as city gas, it is desulfurized and supplied to the reforming catalyst layer side. An oxidant gas is supplied to the cathode layer side. As the oxidant gas, oxygen-enriched air, oxygen, and the like are used in addition to air.

<Specific Example of Reformer-Integrated Fuel Cell of the Present Invention>
The reformer-integrated fuel cell of the present invention has the above structure and is manufactured as described above. The following is a specific example of its production. A planar reformer-integrated fuel cell was produced according to the steps of FIGS. NiO-YSZ was used as the porous reforming catalyst layer. As shown in FIG. 17A, a La _0.8 Ca _0.2 CrO _{3 ± δ} paste was formed as a barrier layer 2 on the porous reforming catalyst layer 1 by a printing method, and baked by heating to 1400 ° C. Thereafter, a Pd film was formed as a hydrogen separation / anode layer 3 on the barrier layer 2 by plating. FIG. 17B shows this stage.

Next, an alkoxide solution containing BaCe _0.8 Y _0.2 O _{3 ± δ} and Ba / Ce / Y in the ratio of 0.8 / 0.2 is applied as the electrolyte layer 4 on the hydrogen separation / anode layer 3. After forming by repeating the calcination step several times, it was finally heated to 1100 ° C. and sintered. FIG. 17C shows this stage. Further, a paste of La _0.6 Sr _0.4 CoO _{3 ± δ} was formed by a printing method as a cathode and baked at 1000 ° C.

The figure explaining the basic composition of the present invention Diagram showing an outer membrane cylindrical reaction tube with a "reforming catalyst and support" configured in a cylindrical shape The figure which shows the aspect which provides a barrier layer in the surface of the "reforming catalyst and support body" applied by this invention The figure explaining the cylindrical fuel cell which concerns on this invention The figure which shows the cylindrical fuel cell which concerns on this invention as a perspective view The figure explaining the reformer integrated fuel cell of an elliptical cross section according to the present invention The figure explaining the reformer integrated fuel cell of the cross-sectional rectangular shape which concerns on this invention The figure which shows a cross-sectional rectangular fuel cell comprised like FIG.7 (b) as a perspective view. The figure explaining the reformer integrated fuel cell of the cross section square shape concerning the present invention FIG. 2 is a diagram for explaining a reformer-integrated fuel cell having a circular cross section having an air passage SA inside. The figure explaining the flat reformer integrated fuel cell concerning the present invention The figure which shows the aspect which laminates | stacks by laminating | stacking several flat fuel cells side by side The figure which shows the aspect which laminates | stacks several flat fuel cells, and is made into a stack The figure explaining the horizontal striped plate-shaped reformer integrated fuel cell of the present invention The figure explaining the reformer integrated fuel cell of the horizontal stripe-shaped cross section of the present invention The figure explaining the reformer integrated fuel cell of the other horizontal stripe-shaped cross-sectional rectangular shape of this invention The figure which shows the specific example of preparation of the reformer integrated fuel cell of this invention Diagram showing a steam reformer The figure which shows the example which installs the hydrogen purifier after the former reformer Diagram showing membrane reactor Cross section of a fuel cell with hydrogen purification function for the supplied fuel gas (prior art)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Porous reforming catalyst layer which is 1st layer 2 Barrier layer which is 2nd layer 3 Hydrogen separation and anode layer which is 3rd layer 3 'Layer thickness part (current extraction terminal) of hydrogen separation and anode layer 3 )
4 Electrolyte layer as fourth layer 5 Cathode layer as fifth layer S Inner air flow path (fuel flow path) of porous reforming catalyst layer 1
SA air flow path SE separator SU electrically insulating porous substrate IN interconnector 10 oxygen electrode 30 hydrogen electrode 40 electrolyte membrane 42, 44 electrolyte layer 41, 45 palladium coating 43 dense substrate 43

Claims (18)

  A fuel cell in which a fuel reformer and a fuel cell are integrated, wherein a barrier layer, a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer are sequentially disposed on a porous reforming catalyst layer. A reformer integrated fuel cell.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, and an electrolyte layer are sequentially formed on a porous reforming catalyst layer having a circular cross section having a fuel flow path therein. And a reformer-integrated fuel cell comprising a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, and an electrolyte layer are sequentially formed on a porous reforming catalyst layer having an elliptical cross section having a fuel flow path therein. And a reformer-integrated fuel cell comprising a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, and an electrolyte layer are sequentially formed on a porous reforming catalyst layer having a rectangular cross section having a fuel flow path therein. And a reformer-integrated fuel cell comprising a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, and an electrolyte layer are sequentially formed on a porous reforming catalyst layer having a polygonal cross section having a fuel flow path therein. And a reformer-integrated fuel cell comprising a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation and anode layer are sequentially formed on an inner circumferential surface of a porous reforming catalyst layer having a circular cross section having an air channel inside, A reformer-integrated fuel cell comprising an electrolyte layer and a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, in order, on the inner peripheral surface of a porous reforming catalyst layer having an elliptical cross section having an air channel inside, A reformer-integrated fuel cell comprising an electrolyte layer and a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer are sequentially formed on the inner peripheral surface of a porous reforming catalyst layer having a rectangular cross section having an air flow path therein, A reformer-integrated fuel cell comprising an electrolyte layer and a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation and anode layer are sequentially formed on an inner peripheral surface of a porous reforming catalyst layer having a polygonal cross section having an air channel inside, A reformer-integrated fuel cell comprising an electrolyte layer and a cathode layer.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a barrier layer, a hydrogen separation / anode layer, an electrolyte layer, and a cathode layer are sequentially disposed on a flat porous reforming catalyst layer. A reformer-integrated fuel cell.   A fuel cell in which a fuel reformer and a fuel cell are integrated, and a porous reforming catalyst layer, a barrier layer, and a hydrogen separation / anode on an electrically insulating porous substrate tube having a fuel flow path therein A plurality of power generating element portions having a layer structure in which a layer, an electrolyte, and a cathode layer are sequentially stacked are formed adjacent to each other, and at least one adjacent power generating element portion is electrically connected in series by an interconnector. A reformer-integrated fuel cell.   A fuel cell in which a fuel reformer and a fuel cell are integrated, each having a fuel flow path inside and a reforming catalyst porous substrate tube having a barrier layer on the surface, a hydrogen separation and anode layer, an electrolyte And a plurality of power generation element portions having a layer structure in which a cathode layer is sequentially laminated, and at least one adjacent power generation element portion is electrically connected in series by an interconnector. A reformer integrated fuel cell.   The reformer-integrated fuel cell according to any one of claims 11 to 12, wherein the porous substrate tube has a hollow plate shape.   The reformer-integrated fuel cell according to any one of claims 11 to 12, wherein the porous substrate tube has a hollow cylindrical shape.   The constituent material of the porous reforming catalyst layer is a sintered body of a mixture of nickel and yttria stabilized zirconia, a sintered body mainly composed of a mixture of nickel and stabilized zirconia, porous ceramics or porous cermet. The reformer-integrated fuel cell according to any one of claims 1 to 14, wherein: The constituent material of the barrier layer is stabilized zirconia, partially stabilized zirconia, zirconia, alumina, magnesia, (Ln _{1 -x} A _x ) _y MO _{3 ± δ} (where Ln is a rare earth element, A is Ba, Sr) Or Ca and M are Cr or Ti, the range of x is 0 ≦ x ≦ 1, and the range of y is 0.9 ≦ y ≦ 1.1), or a mixture of these materials, or those materials The reformer-integrated fuel cell according to any one of claims 1 to 15, wherein   The constituent material of the hydrogen separation / anode layer is a Pd film, a Pd alloy film, a Group 5 metal (V, Nb or Ta) film, a Group 5 alloy film, a Group 5 metal film or a Group 5 alloy film and a Pd film, or The reformer-integrated fuel cell according to any one of claims 1 to 16, wherein the fuel cell is a multilayer film with a Pd alloy film. The constituent material of the electrolyte layer is a perovskite compound represented by the formula: ABO ₃ (wherein A is Ba, Sr or Ca, B is Ce or Zr. Ce and Zr of B site are partly Y, Yb 18) The reformer-integrated fuel cell according to any one of claims 1 to 17, wherein the main component is a rare earth element such as

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