JP4421542B2 - Catalyst structure for fuel cell system and fuel cell system - Google Patents

Description

  The present invention relates to a catalyst structure for a fuel cell system and a fuel cell system.

  In recent years, development of a small reactor using a flow channel structure in which a reaction flow channel is provided has been activated. For example, Patent Document 1 describes a chemical reaction apparatus that generates a chemical reaction for converting a first fluid substance into a second fluid substance in a reaction channel formed continuously on a micro substrate. This flow path structure includes a micro substrate such as silicon and a closed substrate such as a glass substrate. The minute substrate is provided with a groove on one surface side by etching into an arbitrary groove shape using a photo etching technique or the like. A copper-zinc based catalyst is deposited on the inner wall surface of the groove by CVD or the like. The closed substrate is bonded so as to face one surface provided with the groove of the minute substrate. As a result, a reaction channel having a catalyst provided therein is formed. Such a small reactor is incorporated in the fuel cell system and contributes to miniaturization of the fuel cell system.

  In general, a catalyst is supported at a uniform concentration inside a reaction channel of a small reactor, as in a catalyst body described in Patent Document 2 or Patent Document 3, for example.

In Patent Document 2, as a CO selective oxidation catalyst that oxidizes CO to CO ₂ but does not oxidize H ₂ , MnO ₂ , Co ₃ O ₄ , 2CuO · Cr ₂ O ₃ , Al ₂ O ₃ , and Ag are used. _A hydrogen gas refining catalyst for fuel cells is disclosed, in which a supported catalyst (Pt-black) is dispersed on the surface of a composite oxide containing ₂ O.

  Patent Document 3 discloses a catalyst body in which a catalyst is supported on the surface of a linear, thread-like, hollow tubular, net-like or cloth-like metal material having an alumina layer or a layer mainly composed of alumina on the surface. It is disclosed. An ultrafine platinum catalyst is used as the catalyst. In this catalyst body, in order to increase the reaction amount of the catalytic reaction, a uniform γ-alumina layer is formed on the surface of the metal carrier, and the catalyst loading is increased to make the catalyst loading uniform.

  However, while the method of supporting the catalyst uniformly has the advantage that it is easy to manufacture, when the chemical reactions occurring in the fuel cell system are sequential or multi-stage, each catalyst that constitutes each chemical reaction is prepared. Since the reaction efficiency is low, there is a downside to downsizing the reactor.

  In addition, it is common to make the composition concentration profile of the catalyst uniform in the reaction flow path, but there is also a method of changing the concentration of the composition. As specific examples, Patent Documents 4 and 5 propose a method of providing a catalyst concentration difference or density difference in the flow path direction. However, this means alone cannot eliminate the negative aspects of chemical reactions that are sequential or multistage.

  On the other hand, it is considered that the method of using a plurality of types of catalysts is an effective means for downsizing the reactor. However, the conventional method attempts to form a catalyst layer by mixing a catalyst with a slurry and repeatedly applying it to a substrate.

For example, Patent Document 6 describes a multilayer catalyst for exhaust treatment of a diesel engine, in which a Pt—Al ₂ O ₃ catalyst layer and a ZrO ₂ catalyst layer are sequentially deposited on the surface of a refractory ceramic carrier. Patent Document 7 describes a multi-layered catalyst layer in which coating layers having different compositions are formed on the surface of a plate-like catalyst. Both catalyst layers are formed by applying a slurry to a substrate. It is a thing.

  In Patent Document 8, a reforming catalyst layer having an average pore diameter smaller than the average pore diameter of the porous body is provided on the outer surface of the porous body, and the modified catalyst layer is formed on the outer surface of the reforming catalyst layer. A composite catalyst membrane provided with a CO removal catalyst layer having an average pore size smaller than the average pore size of the porous catalyst layer is disclosed. This composite catalyst membrane is also manufactured by forming a precursor solution of a reforming catalyst layer on a porous body and baking it, and forming a CO removal catalyst precursor sol on this surface, drying and baking. ing.

These conventional multi-layered catalysts can certainly support multiple types of catalysts, but because the interface is formed between the catalyst layers, the interaction between the catalyst layers does not work sufficiently, and the chemical progresses sequentially or in multiple stages. The reaction efficiency was not sufficient for the reaction. In addition, since components embedded in the slurry are also generated, there are disadvantages not only in terms of reaction efficiency but also in terms of economy and resource conservation when supporting a noble metal catalyst. Furthermore, when a transmissive configuration such as a membrane as in Patent Document 8 is used, there is a problem that if a pinhole is formed in the membrane, high concentration CO permeates downstream.
JP 2003-88754 A Japanese Patent Laid-Open No. 2002-210367 JP-A-4-354544 JP-A-7-85874 JP 7-12002 A Japanese Patent Laid-Open No. 10-244154 Japanese Patent Application Laid-Open No. 11-57495 JP 2004-290805 A

  An object of the present invention is to provide a fuel cell system catalyst structure and a fuel cell system capable of efficiently proceeding with a chemical reaction that proceeds sequentially or in multiple stages.

The catalyst structure for a fuel cell system of the present invention comprises an unsupported catalyst layer,
A supported catalyst layer including a support and catalyst particles supported on the support, and thermally continuous with the unsupported catalyst layer,
Wherein the carrier-supported catalyst layer and the unsupported catalyst layer Ri integral structure der,
The supported catalyst layer has a larger average pore diameter than the unsupported catalyst layer .

The fuel cell system of the present invention includes a fuel tank that contains fuel,
A reforming unit for generating a gas containing hydrogen gas from the fuel;
A fuel cell for generating electricity using the gas containing hydrogen gas and oxygen,
The reforming unit includes an unsupported catalyst layer,
A supported catalyst layer including a support and catalyst particles supported on the support, and thermally continuous with the unsupported catalyst layer,
Wherein the carrier-supported catalyst layer and the unsupported catalyst layer Ri integral structure der,
The supported catalyst layer has a larger average pore diameter than the unsupported catalyst layer .

  ADVANTAGE OF THE INVENTION According to this invention, the catalyst structure for fuel cell systems and fuel cell system which can advance the chemical reaction which advances sequentially or multistage efficiently can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a conceptual diagram of a catalyst structure according to a first embodiment of the present invention.

  The catalyst structure 1 includes an unsupported catalyst layer 3 on a support substrate 2, and a supported catalyst layer 6 including a support 4 and catalyst particles 5 supported on the support 4 on the unsupported catalyst layer 3. I have. As shown in FIG. 1, the unsupported catalyst layer 3 and the support 4 of the supported catalyst layer 6 are a porous body having an integral structure, and there is an interface between the unsupported catalyst layer 3 and the supported catalyst layer 6. There is no thermal continuous state.

  Here, the unsupported catalyst layer 3 is not a layer in which no catalyst is supported, but means a layer that functions as a catalyst even when the catalyst particles 5 are not supported. Specifically, in the case of Example 1 to be described later, the loading amount of the catalyst particles 5 (platinum) is significantly different depending on the analyzing means such as EPMA with respect to the integral structure (alumina) of the unsupported catalyst layer 3 and the support 4. A layer (alumina) that functions as a catalyst even when it is supported on the basis of a detection amount that is less than or equal to a detectable amount.

  The catalyst particles are catalyst species that are supported on an unsupported catalyst layer using a catalyst species (for example, platinum) that is desired to be supported dissolved in an ionic state or dispersed in an emulsion state. To tell.

  The unsupported catalyst layer 3 is made of, for example, a solid acid catalyst, and examples of the solid acid catalyst include an alumina catalyst. The supported catalyst layer 6 that is thermally continuous with the unsupported catalyst layer 3 is obtained by, for example, supporting a noble metal catalyst particle 5 such as platinum (Pt) on a solid acid catalyst that forms the unsupported catalyst layer 3.

  Specific effects of such a catalyst structure will be described by illustrating the following fuel reforming reaction.

For example, consider a reaction in which dimethyl ether (DME) and water are used as fuel for a fuel cell, and a reformed gas containing hydrogen gas is obtained therefrom. In this case, as shown in Formula (1), dimethyl ether (CH ₃ OCH ₃ ) reacts with water (H ₂ O) to become methanol (CH ₃ OH), and further, methanol is converted into water as shown in Formula (2). It reacts with hydrogen (H ₂ ) and carbon dioxide (CO ₂ ).

CH ₃ OCH ₃ + H ₂ O → 2CH ₃ OH (1)
CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (2)
The reaction of the formula (1) mainly occurs on an alumina catalyst (unsupported catalyst layer), and hydrolysis of dimethyl ether proceeds to produce methanol. By this reaction of the formula (2) from methanol, a hydrogen generation reaction proceeds mainly with noble metal-based catalyst particles such as platinum contained in the supported catalyst layer. That is, if methanol is produced in a certain amount quantitatively only by the reaction of formula (1), the reaction does not progress any more due to chemical equilibrium, but the reaction of formula (2) proceeds sequentially. Since the reaction of Formula (1) is promoted, hydrogen gas can be generated efficiently. In particular, since the fuel reforming reaction is an endothermic reaction, it is desirable that the fuel reforming reaction proceed at a high temperature (for example, about 350 to 500 ° C.), and the reaction efficiency is lowered due to the temperature decrease. In the catalyst structure of the present embodiment, heat transmitted from the outside of the catalyst structure can be efficiently transferred from the unsupported catalyst layer to the supported catalyst layer, so that the reaction efficiency can be prevented from decreasing. . More preferably, the carrier substrate 2 and the unsupported catalyst layer 3 are thermally continuous.

In addition to platinum (Pt), for example, ruthenium (Ru), rhodium (Rh), palladium (Pd) or the like can be used as the noble metal catalyst particles used in the fuel reforming reaction. These reforming catalysts can be used alone or in combination of a plurality of types.

The supported catalyst layer preferably has a larger average pore diameter than the unsupported catalyst layer. This is due to the reason explained below.
The catalyst structure according to this embodiment can be provided on the inner wall of the reaction channel of the small reactor. If the average pore size of the supported catalyst layer is smaller than the average pore size of the unsupported catalyst layer, it is difficult for the fuel gas to penetrate to the unsupported catalyst layer even if the fuel gas is circulated through the reaction channel provided with the catalyst structure. The reaction in the unsupported catalyst layer is difficult to proceed, and as a result, the reaction efficiency of the entire reforming reaction may be reduced. On the other hand, the fuel gas permeates from one side of the membrane to the other as in the composite catalyst membrane of Patent Document 8 instead of the flow type in which the fuel gas is passed through the catalyst structure provided in the reaction flow path described above. In the case of the transmission type, this is not limited, but there is a risk of pinholes as described above.

It is preferable that the catalyst particles are continuously supported in the direction in which the successive reaction proceeds from the surface layer portion to the deepest portion of the supported catalyst layer. In this case, the supported amount of catalyst particles may decrease from the surface layer portion toward the deepest portion of the supported catalyst layer. That is, by providing the catalyst structure with a structure that has a characteristically proceeding reaction in the depth direction, durability related to thermal expansion of the catalyst support, etc., and substances in the catalyst support Thus, an appropriate and economical catalyst loading can be ensured while considering the diffusion of the catalyst, and the sequential reaction can proceed more efficiently. This is considered to be due to the reason explained below.
That is, the catalyst particles and the carrier thereof undergo thermal changes due to exothermic reactions and endothermic reactions. Here, when the catalyst structure is thermally continuous, the heat exchange between the exothermic reaction and the endothermic reaction proceeds smoothly, and the thermal loss as a whole can be reduced. In addition, the catalyst particles that are supported have a concentration profile in the depth direction, that is, by gradually increasing or decreasing the supported amount in the depth direction of the catalyst carrier, the local thermal expansion or contraction of the carrier. It is possible to suppress the discontinuity of the substrate and contribute to the maintenance of the structure of the carrier, thereby extending the life of the whole. This is particularly effective when the temperature is unstable when the system is started or stopped, or in an emergency.

  In steady state, the amount of substance reaching the deepest part per unit time is relatively small compared to the surface layer part due to the influence of diffusion, so the reaction efficiency per unit time is higher than that of the deepest part near the surface part. Therefore, it is appropriate and economical also for catalyst production to increase the amount of catalyst supported in the vicinity of the surface layer portion as compared with the deepest portion.

The catalyst structure according to the present embodiment can be produced, for example, by supporting catalyst particles on a porous body of an anodized base material. More specifically, it can be produced as described below.
First, an alumina catalyst as a porous catalyst carrier is obtained by anodizing a base material made of an aluminum metal such as A1050 or an aluminum alloy. Next, a catalyst structure can be obtained by supporting noble metal catalyst particles on the porous catalyst carrier.

  The anodizing treatment can be performed using a known method. For example, the method is described in paragraphs [0005] to [0011] of JP-A No. 2004-154717. The catalyst structure according to the present embodiment can be supported on the reaction channel of the small reactor. When the surface of the reaction channel is formed of aluminum or an aluminum alloy, the porous catalyst carrier can be formed by anodizing the surface of the reaction channel as described above.

  For example, the pore size of the supported catalyst layer and the unsupported catalyst layer can be adjusted by adjusting the pH value or concentration of a treatment solution used for anodizing treatment, for example, a solution containing sulfuric acid, phosphoric acid, or oxalate ions, or the treatment time. Can be controlled.

  Examples of the method of changing the average pore diameter include a method of changing the current density of anodization during the treatment, a method of changing the solution of anodization during the treatment, a method of changing the temperature and concentration of the pore enlargement treatment, and the like. It is done. Of course, by using one or a combination of two or more of these methods, the average pore diameter of the supported catalyst layer can be made larger than the average pore diameter of the unsupported catalyst layer.

  Anodized alumina is formed by such a method, and precious metal catalyst particles are supported on the alumina. As the loading method, a method such as impregnation can be used. It should be noted here that in order to use the anodized alumina as a catalyst, catalyst particles are not supported up to the deepest part of the alumina layer. The catalyst particles are desirably supported at a depth of up to half from the surface of the alumina layer. Specifically, it can be produced by the following production method. That is, the Pt concentration in the solution to be impregnated is adjusted to a predetermined amount to be supported, and time management is made appropriate. For example, in the case of anodized alumina having a film thickness of 40 μm, when immersed in a 1 g-Pt / L chloroplatinic acid solution for about 2 hours, Pt can be supported from the surface of the film to a depth of about 20 μm, and 20 μm to 40 μm from the surface of the film. Is preferable because it can be an unsupported catalyst layer of anodized alumina. Further, impregnation with the catalyst particle precursor solution without removing the air inside the pores is an effective method for preventing the catalyst particles from being supported up to the deepest part of the anodized alumina. This is because the diffusion of the solution is suppressed by air and can be carried near the surface.

  When supporting the catalyst particles, it is possible to support the catalyst particles at once, or to support the catalyst particles in a plurality of times. It is also possible to adjust the depth to be supported (the thickness of the supported catalyst layer) in relation to the impregnation bath. For example, the thickness of the supported catalyst layer and the supported amount of catalyst particles can be controlled by adjusting the concentration of the noble metal in the solution to be impregnated and the impregnation time. The thickness of the supported catalyst layer and the supported amount of catalyst particles can be made suitable according to the amount of fuel to be processed, the size of the reactor to be processed, the gas flow rate, the SV value, and the like.

In the present embodiment, the catalyst structure is described in detail with the catalyst particles supported on the porous body of the anodized base material, but the ceramic molded body is replaced with the anodized base material. It can also be used. As the ceramic molded body, a pressure-molded powder of γ-Al ₂ O ₃ can be used.

(Second Embodiment)
In the first embodiment, the catalyst structure having the two catalyst layers has been described. However, the catalyst structure is not limited to this, and the catalyst layer may have a three-layer structure.
Hereinafter, a catalyst structure having a three-layer structure will be described with reference to FIG.

FIG. 2 is a conceptual diagram of the catalyst structure according to the second embodiment.
The catalyst structure 21 includes a non-supported catalyst layer 23 formed on the support substrate 22, and a first supported catalyst layer that is thermally continuous to the non-supported catalyst layer 23 and includes first catalyst particles 24. 25 and a second supported catalyst layer 27 that is thermally continuous to the first supported catalyst layer 25 and includes the second catalyst particles 26. The support substrate 22 and the unsupported catalyst layer 23 are preferably thermally continuous.

Examples of the first catalyst particles include the aforementioned reforming catalyst. An example of the second catalyst particles is a shift catalyst. The second supported catalyst layer may contain first catalyst particles. By combining the shift catalyst, carbon monoxide (CO), which is a by-product generated when the chemical reaction of Formula (1) and Formula (2) proceeds, is reacted with water (H ₂ O) to produce carbon dioxide ( The shift reaction of the formula (3) using CO ₂ ) and hydrogen (H ₂ ) can be advanced, and the CO concentration in the resulting reformed gas can be reduced.

CO + H ₂ O → H ₂ + CO ₂ (3)
A known catalyst composition can be used as the shift catalyst. For example, those described in JP-A-2004-97946, JP-A-2004-97948, JP-A-2004-261755 and the like can be used. Specifically, platinum (Pt), rhodium (Rh), molybdenum (Mo), rhenium (Re), cerium (Ce) {eg ceria (CeO ₂ )}, alkali metal or alkaline earth metal as a shift catalyst Can be mentioned. Examples of the alkali metal include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and the like. Examples of the alkaline earth metal include solid basic catalysts such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Among these, it is preferable to use at least one of rhenium and ceria. These shift catalysts can be used alone or in combination of a plurality of types.

  The CO shift reaction (hereinafter referred to as a high temperature shift reaction) that proceeds in the second supported catalyst layer is an exothermic reaction, and the reaction does not easily proceed when the temperature becomes too high. A first supported catalyst layer that is thermally continuous to each catalyst layer is provided between the unsupported catalyst layer and the second supported catalyst layer, and a CO shift region is obtained by advancing a reforming reaction (endothermic reaction). Can be prevented from becoming too hot. In addition, by holding a plurality of types of catalyst layers that combine an endothermic reaction and an exothermic reaction in an integrated structure, thermal bondability is increased, which can contribute to an improvement in the efficiency of the reactor. For example, when only the first supported catalyst layer supporting platinum catalyst particles is provided as the supported catalyst layer, the reformed gas contains about 4 to 5% CO. By supporting particulate rhenium and ceria as the second catalyst particles on the first supported catalyst layer and providing the second supported catalyst layer, the multi-stage reaction of the reforming reaction and the high temperature shift reaction causes the The CO concentration can be reduced to about 1000 ppm. The catalyst structure according to the present embodiment is used not only for the above-described reaction using dimethyl ether and water as fuel, but also for the reforming reaction of other fuels, for example, fuels containing alcohols such as ethanol and methanol and water. be able to.

  In order to improve the permeability of the fuel gas, it is desirable that the second supported catalyst layer has a larger average pore diameter than the first supported catalyst layer.

  The catalyst structure of the present embodiment can be produced, for example, by further supporting the second catalyst particles on the catalyst structure of FIG. The carrying method can be performed in the same manner as described in the first embodiment. More specifically, as described in the first embodiment, after the platinum-supported anodized alumina is formed, the precursor catalyst solution of the shift catalyst particles is impregnated and calcined. For example, in the case of anodized alumina having a film thickness of 40 μm, after being immersed in a 1 g-Pt / L chloroplatinic acid solution for about 2 hours to carry Pt from the coating surface to a depth of about 20 μm, about 0.5 hour A catalyst structure having a second supported catalyst layer can be produced by immersing and firing in a shift catalyst solution containing 1 g equivalent / L.

  Although the catalyst structure having a three-layer structure has been described here, a catalyst structure having a structure of four or more layers can be manufactured. For example, a noble metal catalyst such as platinum as a methanol reforming catalyst can be produced on the base material anodized alumina, an aqueous shift catalyst, and an alkali or alkaline earth metal four-layer catalyst can be produced thereon. A supported catalyst layer having a multilayer structure of four or more layers can be produced by repeating the impregnation step.

(Third embodiment)
In the second embodiment, the example in which the reforming catalyst and the high temperature shift catalyst are combined has been described. However, the present invention is not limited to this, and the shift catalyst is used as the first catalyst particle, and the meta is used as the second catalyst particle. Nation catalysts can also be used. By combining the shift catalyst and the methanation catalyst, the shift reaction (hereinafter referred to as the low temperature shift reaction) can be advanced in a lower temperature region than the high temperature shift reaction, and the methanation reaction represented by the formula (4) is advanced. be able to. Thus, the CO concentration contained in the reformed gas can be further reduced by the low temperature shift reaction and methanation reaction that proceed in multiple stages.

CO + 3H ₂ → CH ₄ + H ₂ O (4)
Examples of the low temperature shift catalyst include those similar to the high temperature shift reaction. A known catalyst composition can be used as the methanation catalyst. For example, those described in JP-A No. 2003-340280 can be used. Specifically, examples of methanation catalysts include ruthenium (Ru), nickel (Ni), iron (Fe), manganese (Mn), cobalt (Co), silver (Ag), and rhodium (Rh). . These methanation catalysts can be used alone or in combination of two or more.

  Since both the low temperature shift reaction and the methanation reaction are exothermic reactions, the catalyst structure tends to become high temperature. By making the first supported catalyst layer thermally continuous with the second supported catalyst layer, the heat dissipation efficiency of the catalyst structure can be improved, and the supported catalyst layer is prevented from becoming too hot and shifted. It can prevent that the reaction efficiency of reaction falls. For example, by using the catalyst structure of the present embodiment, a reformed gas having a CO concentration of about 1000 ppm can be purified to a CO concentration of about 10 ppm.

  In the present embodiment, the unsupported catalyst layer plays a role of hydrolyzing and removing dimethyl ether remaining without being reformed in the reformed gas. If the reformed gas contains a large amount of dimethyl ether and is sent to the latter stage of the fuel cell system (for example, a fuel cell 103 described later), carbonization may occur due to combustion of dimethyl ether, or the latter stage catalyst may be poisoned. . According to the catalyst structure of the present embodiment, dimethyl ether can be reduced, and for example, poisoning of the catalyst contained in the fuel electrode of the fuel cell to which the reformed gas is supplied can be suppressed.

  The catalyst structure according to this embodiment can be manufactured in the same manner as in the second embodiment except that the first and second catalyst particles are changed. Further, the catalyst structure according to the third embodiment can be produced by further supporting the methanation catalyst on the catalyst structure according to the second embodiment.

  The catalyst structure of this embodiment is not only a reformed gas obtained using dimethyl ether and water as fuels, but also a modified fuel obtained by reforming other fuels, for example, fuels containing alcohols such as ethanol and methanol and water. It can also be used to reduce the CO concentration of the quality gas.

(Fourth embodiment)
In the third embodiment, the shift catalyst is used as the first catalyst particle and the methanation catalyst is used as the second catalyst particle. However, the catalyst structure is not limited to this. For example, by using at least one of a solid acid catalyst as the unsupported catalyst layer, an acid-base amphoteric catalyst as the first catalyst particles, and a noble metal catalyst and a manganese group catalyst as the second catalyst particles, for example, these are highly functional as a whole. The CO shift catalyst can also be used.

  CO is adsorbed on the surface of the noble metal catalyst on the surface layer. If an acid-base amphoteric catalyst is present adjacent to the noble metal catalyst, the acid-base amphoteric catalyst functions as an alkali metal, so that electrons are donated to the noble metal catalyst. As a result, if the electron density of the noble metal catalyst is increased, CO adsorption becomes relatively strong, and thus the reactivity is increased.

  On the other hand, the solid acid catalyst functions as a fuel hydrolysis catalyst or the like. At this time, the fuel is converted into olefinic hydrocarbons to cause polymerization, which may adversely affect the subsequent fuel cell system. Here, since the acid sites of the solid acid catalyst are neutralized due to the adjacent acid-base amphoteric catalyst, this problem can be avoided.

  As described above, the combination of the solid acid catalyst, the acid-basic amphoteric catalyst, the noble metal catalyst, and the manganese group catalyst enables the CO shift reaction to proceed efficiently.

  As the noble metal catalyst, platinum (Pt), rhodium (Rh), ruthenium (Ru), palladium (Pd), osmium (Os), or iridium (Ir) described in the second embodiment can be used. As the manganese group catalyst, rhenium (Re), technetium (Tc), or manganese (Mn) can be used.

As the acid-base amphoteric catalyst, ceria (CeO ₂ ) or zirconia (ZrO ₂ ) can be used.

As the solid acid catalyst, silica (SiO ₂ ) or the like can be used in addition to alumina (Al ₂ O ₃ ).

  The catalyst structure according to this embodiment can be manufactured in the same manner as in the second embodiment except that the first and second catalyst particles are changed. Further, the catalyst structure according to the second embodiment can be produced by further supporting a methanation catalyst on the catalyst structure according to the present embodiment.

  The catalyst structure of this embodiment is not only a reformed gas obtained using dimethyl ether and water as fuels, but also a modified fuel obtained by reforming other fuels, for example, fuels containing alcohols such as ethanol and methanol and water. It can also be used to reduce the CO concentration of the quality gas.

The catalyst structure according to the embodiment of the present invention can be applied to a small reactor. Hereinafter, the small reactor will be described with reference to FIG.
FIG. 3 is an exploded perspective view showing a small reactor.
The small reactor 31 includes a flow channel structure 40 including a first flow channel component member 32 and a second flow channel component member 33, a housing 34, and a lid 35. The first flow path component member 32 includes a rectangular plate-shaped member 36, and a plurality of plate-shaped flow path fins 37 are arranged in parallel on the plane portion of the plate-shaped member 36 perpendicular to the longitudinal direction. Yes. The plate-like member 36 and the flow path fins 37 may be integrally formed. The second flow path component member 33 includes a plate-like member 38 having the same size as the first flow path component member 32 and a similar structure, and a plurality of flow channel fins 39. A catalyst structure is formed on the surfaces of the channel fins 37 and 39. When the channel fins 37 and 39 are made of aluminum metal or aluminum alloy or have a film of aluminum metal or aluminum alloy, the surface of the channel fins 37 and 39 is formed by the manufacturing method using the anodizing process described above. A catalyst structure can be formed. It is desirable that the catalyst structure is formed over the entire surfaces of the channel fins 37 and 39.

  The flow path structure 40 is configured such that the first flow path component member 32 and the second flow path structure member 33 are opposed to each other on the surface on which the flow path fins 37 and 39 are provided. 39 are fitted so as to be alternately arranged with a gap. The flow path structure 40 having such a structure includes a plurality of parallel flow paths 41 formed between the flow path fins 37 and the adjacent flow path fins 39.

  The casing 34 has a rectangular parallelepiped shape, and a fitting portion 34 a for accommodating the flow path structure 40 is formed. The fitting portion 34 a is formed so that the length of the side perpendicular to the longitudinal direction is slightly larger than that of the flow path structure 40. A supply port 42 is provided in one of the end portions orthogonal to the length of the housing 34, and a discharge port 43 is provided in the other end. Each of the supply port 42 and the discharge port 43 communicates with the fitting portion 34a, and the supply port 42 and the discharge port 43 are provided so as to be positioned on a diagonal line on the opening surface of the fitting portion 34a. The flow path structure 40 described above is accommodated in the fitting portion 34a of the housing 34 so that the plate-like member 36 or the plate-like member 38 becomes the bottom surface, and the lid 35 is disposed thereon. Thereby, a plurality of parallel flow paths 41 of the flow path structure 40 and two orthogonal flow paths (not shown) communicating with the parallel flow paths 41 are formed inside the fitting portion 34a. A supply port 42 communicates with one of these orthogonal flow paths, and a discharge port 43 communicates with the other.

  When a fluid is supplied to the small reactor 31 from the supply port 42, the fluid flows through each parallel channel 41 through the orthogonal channel. At this time, sequential or multistage reactions proceed with the catalyst structure formed in the channel fins 37 and 39. The fluid after the reaction is discharged from the discharge port 43. If the catalyst structure according to the embodiment of the present invention is used, sequential or multistage reactions can be efficiently advanced, which can contribute to miniaturization of the reactor.

  Since the reaction proceeds gradually in the direction of the channel, it is also effective to have a concentration profile in the direction of the channel. That is, by preparing a plurality of flow path structures 40 having different concentration profiles in the depth direction and arranging them appropriately in the flow path direction of the flow path structures 40 and the housing 34 according to the progress of the reaction. Thus, it is possible to provide the small reactor 31 in which the thermal exchange related to the reaction is appropriately managed and controlled.

Next, a fuel cell system in which the catalyst structure according to the embodiment of the present invention is used will be described with reference to FIG.
FIG. 4 is a conceptual diagram of the fuel cell system.
The fuel cell system 100 includes a fuel supply tank 101, a reforming unit 102, and a fuel cell 103. Fuel is stored in the fuel supply tank 101.

  The reforming unit 102 includes, for example, a vaporizer, a reformer, a CO remover, and a combustor. The carburetor is for vaporizing the fuel supplied from the fuel supply tank 101. The reformer is for generating a reformed gas containing hydrogen gas from the fuel vaporized by the vaporizer. In the reformer, a reforming reaction and, if necessary, a high temperature shift reaction proceed. The reformer is set at about 350 ° C., for example. The CO remover is for purifying the reformed gas by reducing the CO concentration of the reformed gas generated by the reformer. In the CO remover, CO is removed by, for example, a low temperature shift reaction and a methanation reaction. The CO remover is set at about 250 ° C., for example. The combustor promotes the combustion reaction of the reformed gas discharged from the fuel cell. In the fuel cell system 100 of FIG. 4, it is possible to use the small reactor described above for each process responsible for reforming reaction, shift reaction, methanation reaction, and combustion reaction. These reforming reactions, shift reactions, methanation reactions, and combustion reactions are combined to form a broadly defined reforming section (reforming unit 102). As the catalyst provided in the reformer, the catalyst structure of the first or second embodiment is preferably used. In particular, it is desirable to use the catalyst structure of the second embodiment for a reformer. As the catalyst provided in the CO remover, it is preferable to use the catalyst structure of the third embodiment, but when the reformer provided with the catalyst structure of the first or second embodiment is used. Other known CO removal catalysts can be used. Similarly, when the CO remover provided with the catalyst structure of the third embodiment is used, a reformer provided with another known reforming catalyst can be used.

  The fuel cell 103 includes an electromotive unit that includes a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode. In this electromotive section, a power generation reaction proceeds using hydrogen-purified gas supplied from the reforming unit 102 to the fuel electrode and air containing oxygen supplied to the oxidizer electrode.

  Fuel is supplied from the fuel tank 101 to the reforming unit 102, where reformed gas containing hydrogen gas is generated and purified. The obtained hydrogen purification gas is supplied to the fuel electrode of the electromotive part of the fuel cell 103 and used for the power generation reaction. The off-gas of the fuel cell 103 containing exhaust and residual hydrogen is sent to the reforming unit 102 again, burned by the combustor, and then released into the atmosphere.

[Example]
Hereinafter, embodiments of the present invention will be described by way of examples.

Example 1
<Production of catalyst structure>
Flow path components A and B having aluminum flow path fins made of A1050 material were prepared. In the flow path component A and the flow path structure member B, the thickness of the flow channel fins is 0.3 mm, and the pitch of the flow channel fins is 0.9 mm. The channel fins of these channel members A and B were anodized as described below to form alumina having a thickness of 80 μm.
That is, an oxalic acid aqueous solution (2 to 5 wt%) was used for anodization, and anodization was performed at a current density of 50 A / m ² for 18 hours. After baking this at 350 degreeC once, it immersed in the oxalic acid aqueous solution (2-5 wt%) at 25 degreeC for 4 hours, and performed the pore expansion process. Further, after baking at 350 ° C., it was immersed in ion exchange water at 80 ° C. for 2 hours, and then fired at 500 ° C. as a carrier for the flow path component. Of course, the anodic oxidation treatment is not limited to these, and inorganic acids such as sulfuric acid and phosphoric acid, and organic acids such as malonic acid and citric acid can be used as appropriate.

Platinum catalyst particles were supported on the anodized flow path component by the impregnation method described below.
That is, the anodized channel fin was immersed in a 1.0 g-Pt / L chloroplatinic acid solution to which an ammonia solution (35%) was added and the pH was made alkaline for 2 hours, and at 25 ° C. for 12 hours. The catalyst structure which has a structure shown in FIG. 1 was obtained by drying and baking at 500 degreeC for 4 hours. In addition, in order to increase the carrying amount, ultrasonic waves were used in combination.

About the obtained catalyst structure, the thickness of the supported catalyst layer and the concentration profile of the catalyst particles were measured using EPMA. The result of the concentration profile is shown in FIG. In FIG. 5, the vertical axis indicates the depth direction of the catalyst structure (in the figure, the upper part indicates the surface layer part and the lower part indicates the deepest part), and the horizontal axis indicates the amount of catalyst particles supported.
As shown in FIG. 5, it is a supported catalyst layer 6 on which platinum catalyst particles are supported at a depth of 40 μm from the surface, and does not contain platinum catalyst particles from a depth of 40 μm to 80 μm (the amount of platinum supported is The unsupported catalyst layer 3 was supported only by a detection amount or less that can be discriminated whether or not there is a significant difference by an analysis means such as EPMA. Further, the supported amount of platinum catalyst particles decreased in the depth direction from the surface layer portion of the supported catalyst layer 6 toward the deepest portion. In FIG. 5, reference numeral 2 indicates a portion (carrier substrate) that is not anodized in the channel fin.

<Assembly of small reactor>
The flow path component member A and the flow path component member B are fitted to face each other so that the flow path fins are alternately arranged to form a flow path structure having a parallel flow path having a flow path width of 0.15 mm. A small reactor having the structure shown in FIG. 3 is assembled by packing the flow channel structure into the fitting portion of the flow channel component (housing), placing the flow channel component (lid) thereon, and welding it. It was.

Dimethyl ether and water were supplied to this small reactor to generate hydrogen. The condition is 1: 4 in terms of a molar ratio of dimethyl ether to water (CH ₃ OCH ₃ : H ₂ O). A small reactor is heated to 350 ° C., and the mixed gas of dimethyl ether and water is circulated at a rate of 0.6 cm ² / sccm (the geometric area of the flow path with respect to the gas flow rate per minute in the standard state). Obtained. The geometric area (total area) of the channel fin on which the catalyst was supported was 150 cm ² .

  Table 1 shows the amount of hydrogen gas (gas generation amount) in the resulting reformed gas and the CO concentration in the reformed gas.

(Example 2)
Cerium nitrate hexahydrate _{(Ce (NO 3) 3 ·} 6H 2 O) into an aqueous solution of 1 g / mL. The channel constituent member A and the channel constituent member B of Example 1 were immersed in this. At this time, after being irradiated with ultrasonic waves for 3 minutes, it was immersed for 16 hours. Then, after drying at 120 ° C. for 1 hour, the temperature was raised to 500 ° C. at 5 ° C./min, and kept for 3 hours as it was to allow natural cooling.

Next, chloroplatinic acid hexahydrate (H ₂ PtCl ₆ .6H ₂ O) is made into an aqueous solution of about 10 mg / mL, and ammonia water (35% stock solution) is added to this to make the pH about 11, and further to this NH ₄ ReO ₄ was dissolved to a concentration of 50 mg / mL. The flow path component A and the flow path component B were immersed in this mixed solution, irradiated with ultrasonic waves for 3 minutes, and subsequently immersed and supported for 16 hours. Then, after drying at 120 ° C. for 1 hour, the temperature is raised to 400 ° C. at 5 ° C./min, held for 3 hours, allowed to cool naturally, and then fired, whereby the catalyst structure according to the second embodiment Was made. In addition, in order to deaerate this time, the ultrasonic wave was used for about 3 minutes, but it is also effective to continuously use the ultrasonic wave in order to increase the carrying amount. The concentration profile of the obtained catalyst structure is shown in FIG. In FIG. 6A, the vertical axis indicates the depth direction of the catalyst structure, and the horizontal axis indicates the amount of catalyst particles supported.

  As shown in FIG. 6A, in the first supported catalyst layer 25, the supported amount of platinum catalyst particles decreases in the depth direction from the surface layer portion toward the deepest portion, and the second supported catalyst layer In No. 27, the supported amounts of rhenium particles, ceria particles, and platinum catalyst particles decreased in the depth direction.

Further, the obtained catalyst structure, pore size distribution (BJH method) measured by N ₂ adsorption method to calculate the average pore diameter. The result is shown in FIG. In FIG. 6B, the vertical axis indicates the depth direction of the catalyst structure, and the horizontal axis indicates the size of the pore diameter.
As a result, the average pore diameter of each catalyst layer was about 5 nm for the unsupported catalyst layer 23, about 20 nm for the first supported catalyst layer 25, and about 50 nm for the second supported catalyst layer 27. Further, as apparent from FIG. 6B, the pore diameter decreased in the depth direction from the surface layer portion of the catalyst structure to the deepest portion (support base material 22).

  Of course, these pore diameters can be appropriately adjusted. Examples of the adjustment method include a method of changing the current density of anodic oxidation, a method of changing the anodic oxidation solution in the middle, and a method of appropriately changing the temperature and concentration of the pore enlargement treatment. These can be used in appropriate combination.

A small reactor was formed in the same manner as in Example 1 except that the obtained flow path component having the catalyst structure was used, and a mixed gas was circulated to obtain a reformed gas.
As a result, 238 sccm (equivalent to 238 cc / min in the standard state) was obtained as hydrogen gas. Table 1 shows the CO concentration in the resulting reformed gas.

FIG. 6C shows the temperature distribution of the catalyst structure when the mixed gas is circulated. In FIG. 6C, the vertical axis indicates the depth direction of the catalyst structure, and the horizontal axis indicates the temperature.
As apparent from FIG. 6C, the unsupported catalyst layer 23 close to the heat source in the catalyst structure was 350 ° C., whereas the second supported catalyst layer 27 was maintained at 300 ° C. . This is because the exothermic reaction proceeds in the unsupported catalyst layer 23 and the second supported catalyst layer 27, but the endothermic reaction proceeds in the first supported catalyst layer 25 that is thermally continuous to the catalyst layers 23 and 27. This is because an excessive increase in the temperature of the two supported catalyst layers 27 could be suppressed.

(Example 3)
Ruthenium (III) acetylacetonate (Ru (acac) ₂₎ is dissolved in and adjusted to 52 mg / mL in acetone, to which the passage component A and the flow path forming member B of Example 2 was immersed 16 hours, Impregnation was supported. Then, it dried at 120 degreeC for 1 hour, heated up to 500 degreeC at 5 degree-C / min, and kept as it was for 2 hours, Then, it was left to cool naturally, The catalyst structure which concerns on 3rd Embodiment was produced. The concentration profile of the obtained catalyst structure is shown in FIG. In FIG. 7, the vertical axis indicates the depth direction of the catalyst structure, and the horizontal axis indicates the amount of catalyst particles supported.

  As shown in FIG. 7, in the first supported catalyst layer 25, the supported amount of platinum catalyst particles, rhenium particles, and cerium particles decreases in the depth direction from the surface layer portion toward the deepest portion. In the catalyst layer 27, the supported amounts of ruthenium particles, rhenium particles, cerium particles, and platinum catalyst particles decreased in the depth direction.

A small reactor was formed in the same manner as in Example 1 except that the flow path component having the obtained catalyst structure was used. This small reactor is heated to 250 ° C., and the reformed gas obtained in Example 2 is circulated at 0.4 cm ² / sccm (flow path geometric area with respect to gas flow rate per minute in the standard state) to purify hydrogen. Got gas. Table 1 shows the amount of generated hydrogen purification gas and the CO concentration in the hydrogen purification gas.

Example 4
A flow path component A and a flow path component B having aluminum flow path fins made of A1050 were prepared in the same manner as in Example 1. In the flow path component A and the flow path structure member B, the thickness of the flow channel fins is 0.3 mm, and the pitch of the flow channel fins is 0.9 mm. The channel fins of these channel members A and B were anodized by the same method as in Example 1 to form alumina having a film thickness of 80 μm.
To this, a 1 g / mL aqueous solution of cerium nitrate hexahydrate (Ce (NO ₃ ) ₃ .6H ₂ O) is first prepared in the same manner as in Example 2, and the above-mentioned flow path component is immersed in this solution. It was. At this time, after irradiating with ultrasonic waves for 3 minutes, it was immersed for 16 hours, then dried at 120 ° C. for 1 hour, then raised to 500 ° C. at 5 ° C./minute, and kept for 3 hours as it was to be naturally cooled. I let you.

Next, chloroplatinic acid hexahydrate (H ₂ PtCl ₆ .6H ₂ O) is made into an aqueous solution of about 10 mg / mL, and ammonia water (35% stock solution) is added to this to make the pH about 11, and further to this NH ₄ ReO ₄ was dissolved to a concentration of 50 mg / mL. The flow path component was immersed in this mixed solution, irradiated with ultrasonic waves for 3 minutes, and subsequently immersed for 4 hours to be impregnated and supported. Then, after drying at 120 ° C. for 1 hour, the temperature is raised to 400 ° C. at 5 ° C./min, held for 3 hours, allowed to cool naturally, and then calcined, whereby the catalyst structure according to the fourth embodiment The body was made. In addition, in order to deaerate this time, the ultrasonic wave was used for about 3 minutes, but it is also effective to continuously use the ultrasonic wave in order to increase the carrying amount. The concentration profile of the obtained catalyst structure is shown in FIG. In FIG. 8, the vertical axis indicates the depth direction of the catalyst structure, and the horizontal axis indicates the amount of catalyst particles supported.

  As shown in FIG. 8, in the first supported catalyst layer 25, the supported amount of ceria particles that are acid-base amphoteric catalysts decreases in the depth direction from the surface layer portion toward the deepest portion, and the second supported catalyst layer. In the layer 27, the supported amounts of rhenium particles as a manganese group catalyst and platinum catalyst particles as a noble metal catalyst decreased in the depth direction.

A small reactor similar to that of Example 1 was formed by using the obtained flow path component having the catalyst structure, and a reforming simulation gas was circulated to perform a CO gas shift test. The catalyst-supported geometric area of the small-size reaction channel fin is 150 cm ² , the reaction temperature is 300 ° C., and the geometric area per unit flow rate is 0.7 cm ² / sccm (flow rate relative to the gas flow rate per minute in the standard state). Road geometric area).

A reforming simulation gas containing H ₂ , CO, CO ₂ , CH ₄ and H ₂ O (H ₂ : 50%, CO: 3.5%, CO ₂ : 15%, CH ₄ : 5%, H ₂ O: 26.5%) was allowed to flow, and the CO concentration could be reduced to 1.5%.

(Comparative Example 1)
Except for changing the concentration of the anodizing solution and the impregnation time, the channel fins of the channel structures A and B were anodized in the same manner as in Example 1 to form alumina having a thickness of 40 μm. On top of this, a slurry in which a platinum alumina catalyst and an alumina catalyst were mixed with a known alumina binder was prepared, and this was repeatedly applied and dried, and baked to a thickness of 40 μm to obtain a catalyst structure. At this time, the ratio of the platinum-alumina catalyst was adjusted so that the supported amount of the catalyst structure of Example 1 and platinum catalyst particles was the same. In addition, the thickness of the channel fin was adjusted in advance so that the channel width of the parallel channel was 0.15 mm.

  When the concentration profile of the obtained catalyst structure was measured, a catalyst layer made of an alumina sintered body carrying platinum catalyst particles on an anodized alumina was formed. In this catalyst layer, platinum catalyst particles were almost It was uniformly dispersed.

  A small reactor was formed in the same manner as in Example 1 except that the obtained flow path component having the catalyst structure was used, and a mixed gas was circulated to obtain a reformed gas. Table 1 shows the amount of hydrogen gas in the reformed gas and the CO concentration in the reformed gas.

(Comparative Example 2)
Except for changing the concentration of the anodizing solution and the impregnation time, the channel fins of the channel structures A and B were anodized in the same manner as in Example 1 to form alumina having a thickness of 40 μm. The pore size distribution (BJH method) of the alumina layer was measured by a nitrogen adsorption method, and the average pore size was calculated to be 50 nm. On this, the colloidal solution of a precursor of γ-Al ₂ O ₃ (carrier), Pt reforming catalyst precursor sol adding a metal salt containing (active ingredient of the reforming catalyst) and dip coating, After drying, it was fired at 300 to 700 ° C. This coating, drying, and firing operations were repeated to form a reforming catalyst layer having a thickness of 20 μm. At the same time, a part of the reforming catalyst precursor sol is dried as it is to prepare a powder-shaped reforming catalyst, and a sintered body fired at 300 ° C. to 700 ° C. is used, and a pore size distribution (BJH method) is obtained by a nitrogen adsorption method. ) And the average pore diameter was calculated to be 0.7 nm.

To the surface of the resulting reforming catalyst layer, 0.5 mol of water and 0.001 mol of hydrochloric acid were added to an alkoxide solution in which 0.05 mol of tetraethoxysilane and 0.05 mol of vinyltriethoxysilane were mixed in ethanol. ethanol solution dropwise, the precursor solution of the carrier obtained by stirring (SiO _2), Pt, the active ingredient of Re (CO removing activity component of the catalyst) metal salt and CeO ₂ (CO removal catalyst containing The CO removal catalyst precursor sol to which the precursor colloid solution was added was dip-coated, dried, and then fired at 300 ° C to 700 ° C. This coating, drying, and firing operations were repeated to form a CO removal catalyst layer having a thickness of 20 μm. At the same time, a part of the CO removal catalyst precursor sol is dried as it is to prepare a powdery CO removal catalyst, and a sintered body fired at 300 ° C. to 700 ° C. is used. ) And the average pore diameter was calculated to be 0.51 nm. The sol concentrations were adjusted so that the supported amounts of the catalyst structure of Example 2 and platinum catalyst particles, ruthenium particles, and ceria particles were the same. In addition, the thickness of the channel fin was adjusted in advance so that the channel width of the parallel channel was 0.15 mm.

  When the concentration profile of the obtained catalyst structure was measured, the active component was present in a substantially uniform manner in both the reforming catalyst layer and the CO removal catalyst layer.

  A small reactor was formed in the same manner as in Example 1 except that the flow path structure member having the obtained catalyst structure was used, and a mixed gas was circulated to obtain a reformed gas. Table 1 shows the amount of hydrogen gas in the reformed gas and the CO concentration in the reformed gas.

(Comparative Example 3)
A catalyst structure was produced in the same manner as in Example 3 except that the flow path structure member of Comparative Example 2 was used, and a small reactor was assembled. A hydrogen-purified gas was obtained by circulating the reformed gas in the same manner as in Example 3 except that this small reactor was used. Table 1 shows the amount of generated hydrogen purification gas and the CO concentration in the hydrogen purification gas.

  As is apparent from Table 1, Examples 1 to 3 each comprising an unsupported catalyst layer and a supported catalyst layer that is thermally continuous with the unsupported catalyst layer, and the support of the supported catalyst layer and the unsupported catalyst layer have an integral structure. In the catalyst structure of No. 3, both the obtained reformed gas and hydrogen purification gas had a low CO concentration, and were not only excellent in reforming efficiency but also excellent in CO removal efficiency. Hereinafter, the description will be made by comparing the catalyst structures carrying the same type of catalyst particles.

  The catalyst structure of Comparative Example 1 had a high CO concentration and a small amount of hydrogen gas in the reformed gas obtained as compared with the catalyst structure of Example 1. This is because, in the catalyst structure of Comparative Example 1, the catalyst layer was formed by applying a gel, so that the anodized alumina layer and the catalyst layer carrier did not have an integral structure, and an interface was formed between the layers to thermally It is thought that it became discontinuous. As a result, it is considered that the amount of heat required for the fuel reforming reaction cannot be efficiently transferred from the alumina layer to the catalyst layer, and the reaction efficiency is lowered. In Comparative Example 1, since the overall reaction efficiency was lowered, the resulting reformed gas contained a large amount of unreacted mixed gas.

  The catalyst structure of Comparative Example 2 corresponding to the composite catalyst membrane of Patent Document 8 applied to the flow type had a higher CO concentration in the reformed gas obtained than the catalyst structure of Example 2. . This is considered to be due to the reason described below. That is, in the catalyst structure of Example 2, as shown in FIG. 6 (c), there was no interface between the catalyst layers and it was thermally continuous. Therefore, the amount of heat required for the fuel reforming reaction Can be efficiently transferred from the unsupported catalyst layer and the second supported catalyst layer to the first supported catalyst layer, whereas in the catalyst structure of Comparative Example 2, there was an interface between the catalyst layers. It is considered that the conductivity is lowered, and as a result, the reaction efficiency is lowered. Furthermore, in the catalyst structure of Comparative Example 2, the average pore diameter of each catalyst layer was smaller than that of the anodized alumina layer, and the average pore diameter of the CO removal catalyst layer was smaller than that of the reforming catalyst layer. It is considered that the reaction efficiency is deteriorated because it is difficult to penetrate the entire structure.

  The catalyst structure of Comparative Example 3 had a higher CO concentration in the hydrogen purification gas obtained than the catalyst structure of Example 3. This is because, in the catalyst structure of Comparative Example 3, the heat conductivity between the anodized alumina layer and each catalyst layer was low, so heat generated in each catalyst layer could not be released outside the catalyst structure, It is considered that the reaction efficiency of the CO removal reaction was lowered due to excessive increase in CO.

  In addition, when the ceramic molded body having an integral structure is used as the support for the unsupported catalyst layer and the supported catalyst layer instead of the anodized alumina, the same results as in Examples 1 to 4 were obtained, either sequentially or in multiple stages. It was confirmed that the proceeding chemical reaction can proceed efficiently.

  From the above results, the reactor (reformer) containing the catalyst structure of Example 1 or Example 2 and / or the reactor (CO remover) containing the catalyst structure of Example 3 or Example 4 It has become clear that the chemical reaction of the fuel cell system can be progressed efficiently or efficiently by using.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

The conceptual diagram which shows the catalyst structure by the 1st Embodiment of this invention. The conceptual diagram which shows the catalyst structure by the 2nd Embodiment of this invention. The disassembled perspective view which shows a small reactor. The conceptual diagram which shows a fuel cell system. 3 is a conceptual diagram showing a concentration profile of a catalyst structure of Example 1. FIG. (A) of the catalyst structure of Example 2 is a conceptual diagram showing a concentration profile, (b) is a conceptual diagram showing a pore size distribution, and (c) is a conceptual diagram showing a temperature distribution. 4 is a conceptual diagram showing a concentration profile of a catalyst structure of Example 3. FIG. The conceptual diagram which shows the density | concentration profile of the catalyst structure of Example 4. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,21 ... Catalyst structure, 2,22 ... Carrier base material, 3,23 ... Unsupported catalyst layer, 4 ... Carrier, 5 ... Catalyst particle, 6 ... Supported catalyst layer, 24 ... First catalyst particle, 25 ... First supported catalyst layer, 26 ... second catalyst particles, 27 ... second supported catalyst layer, 31 ... small reactor, 32 ... first flow path component, 33 ... second flow path component, 34 ... casing, 34a ... fitting portion, 35 ... lid, 36, 38 ... plate-like member, 37, 39 ... channel fin, 40 ... channel structure, 41 ... parallel channel, 42 ... supply port, 43 ... Discharge port, 100 ... fuel cell system, 101 ... fuel supply tank, 102 ... reforming unit, 103 ... fuel cell.

Claims (11)

An unsupported catalyst layer;
A supported catalyst layer including a support and catalyst particles supported on the support, and thermally continuous with the unsupported catalyst layer,
Wherein the carrier-supported catalyst layer and the unsupported catalyst layer Ri integral structure der,
The catalyst structure for a fuel cell system , wherein the supported catalyst layer has a larger average pore diameter than the unsupported catalyst layer . The catalyst particles, catalyst structure of claim 1, wherein the supporting amount toward the deepest portion is reduced from the surface portion of the supported catalyst layer. The supported catalyst layer is thermally continuous to the unsupported catalyst layer and includes a first supported catalyst layer including first catalyst particles, and is thermally continuous to the first supported catalyst layer. claim 1 or 2 catalyst structure according to, characterized in that and a second supported catalyst layers containing second catalyst particles. The first catalyst particles are catalyst particles for promoting an endothermic reaction,
The catalyst structure according to claim 3, wherein the second catalyst particles are catalyst particles for promoting an exothermic reaction. The first catalyst particles are catalyst particles for promoting a reforming reaction,
4. The catalyst structure according to claim 3, wherein the second catalyst particles are catalyst particles for promoting a shift reaction. The catalyst structure according to claim 4 or 5, wherein the second catalyst particles contain at least one of platinum, rhenium, and cerium. The first catalyst particles are catalyst particles for promoting a shift reaction,
The catalyst structure of the second catalyst particles according to claim 3, characterized in that the catalyst particles for promoting the methanation reaction. The unsupported catalyst layer includes a solid acid catalyst;
The first catalyst particles include an acid-base amphoteric catalyst;
The catalyst structure according to claim 3, wherein the second catalyst particles include at least one of a noble metal catalyst and a manganese group catalyst. The solid acid catalyst comprises alumina;
The acid-base amphoteric catalyst comprises cerium;
The catalyst structure according to claim 8, wherein the manganese group catalyst contains rhenium. The catalyst structure according to any one of claims 1 to 8 , wherein the unsupported catalyst layer includes an anodized alumina or a ceramic molded body. A fuel tank containing fuel;
A reforming unit for generating a gas containing hydrogen gas from the fuel;
A fuel cell for generating electricity using the gas containing hydrogen gas and oxygen,
The reforming unit includes an unsupported catalyst layer,
A supported catalyst layer including a support and catalyst particles supported on the support, and thermally continuous with the unsupported catalyst layer,
Wherein the carrier-supported catalyst layer and the unsupported catalyst layer Ri integral structure der,
The fuel cell system , wherein the supported catalyst layer has a larger average pore diameter than the unsupported catalyst layer .

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