JP2006290732A - Method for removing co, apparatus for removing co and its manufacturing method, hydrogen generator using the same and fuel cell system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen generator and a fuel cell system suitable for miniaturization. <P>SOLUTION: A catalyst section composed of aluminum is provided on the surface of a CO removal section which promotes the methanation reaction of a part of carbon monoxide contained in a reformed gas. A catalyst layer in which ruthenium is carried on γ-alumina formed by the anodic oxidation of the surface is provided in the catalyst section. The catalyst section is heated to a temperature of 250°C or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a CO removal method and a CO removal device, and more particularly to a CO removal method, a CO removal device and a manufacturing method thereof suitable for downsizing, a hydrogen generator using the same, and a fuel cell system using the same.

  In recent years, reformers that produce light gas containing hydrogen by reforming light hydrocarbons such as natural gas and naphtha and alcohols such as methanol in the presence of a reforming catalyst and reformed gas have been supplied. There has been developed a fuel cell system that combines a fuel cell having a fuel electrode and an oxidant electrode to which air is supplied. Such a fuel cell system is expected because it has a higher output voltage and higher power generation efficiency than a direct methanol fuel cell using a liquid fuel such as methanol.

  The gas (reformed gas) obtained by reforming alcohols and dimethyl ether contains carbon dioxide and about 1% of carbon monoxide as a by-product in addition to hydrogen. Carbon monoxide degrades the anode catalyst of the fuel cell stack and causes power generation performance to deteriorate. For this reason, when supplying a gas containing hydrogen from the reforming unit to the fuel cell, carbon monoxide is converted into carbon dioxide using a CO shift unit, or a CO selective oxidation unit or a CO methanation unit is used. Fuel cell systems that reduce the concentration of carbon monoxide by converting it to carbon dioxide or methane have also been developed. (Patent Document 1).

  As a catalyst for reducing the carbon monoxide concentration, there is a catalyst in which palladium is supported by anodizing aluminum (Patent Document 2). In Patent Document 2, a reactor using this catalyst from an equilibrium calculation methanates almost all the amount of carbon monoxide at a reaction temperature of 280 ° C. with a gas containing hydrogen containing about 9 mol% of carbon monoxide. It has been shown that it can.

Also known is a catalyst in which aluminum is anodized as a catalyst for reducing the carbon monoxide concentration, an alumina film is formed on the surface, and any one of ruthenium, platinum and rhodium is supported. In the reactor using this catalyst, by setting the outlet temperature of the reactor to 150 ° C. or less, the consumption of hydrogen is small and the concentration of carbon monoxide can be efficiently reduced. (Patent Document 3)
JP 2002-68707 A Paragraphs 0050 to 0054 JP 2003-119002 A paragraphs 0023 to 0027 JP 2003-340280 A paragraphs 0002 to 0017

  However, in order to oxidize carbon monoxide contained in the reformed gas and reduce the concentration of carbon monoxide, it is necessary to separately provide a means for supplying oxygen into the reformed gas, for example, an air pump. The generator and the fuel cell system are increased in size.

  Further, as in Patent Document 2, when anodizing aluminum and methanating carbon monoxide using a catalyst supporting palladium, the concentration of carbon monoxide is reduced, as in Patent Document 2. In the case where no hydrogen separation membrane is used, it has been assumed that hydrogen is consumed by methanation of carbon dioxide as pointed out in Patent Document 3.

  On the other hand, when anodizing aluminum as in Patent Document 3 and carbon monoxide is methanated using a catalyst supporting either ruthenium, platinum, or rhodium to reduce the concentration of carbon monoxide, The consumption of hydrogen as in Patent Document 2 is suppressed. However, as pointed out in Patent Document 3, the catalytic activity was considered to be low at 200 ° C. or lower. Therefore, the ability to reduce carbon monoxide per unit volume of the reactor is reduced, and as a result, a large reactor is required, and the hydrogen generator and the fuel cell system are increased in size.

  The present invention has been made in view of such circumstances, and provides a CO removal method, a CO removal device and a manufacturing method suitable for miniaturization, a hydrogen generator using the same, and a fuel cell system using the same. The purpose is to do.

  In order to achieve the above object, the CO removal apparatus of the present invention promotes a methanation reaction of at least a part of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen. A CO removing unit that removes at least a part of the carbon oxide, a catalyst unit provided in the CO removing unit, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum, and at least a surface of the catalyst unit. A catalyst layer in which ruthenium is supported on alumina that is provided in part and anodized on the surface of the catalyst part, and a heating part for heating the temperature of the catalyst part to 250 ° C. or more. It is characterized by that.

  In order to achieve the above object, the method for producing a CO removal apparatus of the present invention comprises at least a partial methanation reaction of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen. A CO removing unit that promotes and removes at least a part of the carbon monoxide, a catalyst unit that is provided in the CO removing unit, and at least a part of the surface of which is made of aluminum or an alloy containing aluminum, and the catalyst Provided on at least a part of the surface of the catalyst part, the catalyst layer in which the surface of the catalyst part is anodized and on which ruthenium is supported, and heating for heating the temperature of the catalyst part to 250 ° C. or more A method of manufacturing a CO removing device, comprising: anodizing aluminum or an alloy containing aluminum constituting the CO removing portion. The alumina is formed, characterized by impregnating the ruthenium by using an organic salt and an organic solvent of ruthenium to said alumina by.

  In order to achieve the above object, the CO removal method of the present invention promotes a methanation reaction of at least a part of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen. A CO removal section for removing at least a part of the carbon monoxide; a catalyst section provided in the CO removal section, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum; and a surface of the catalyst section. And a catalyst layer in which ruthenium is supported on alumina formed by anodizing the surface of the catalyst part, and a CO removal method using a CO removal apparatus, the catalyst part The temperature of is heated to 250 ° C. or higher.

  In order to achieve the above object, the hydrogen production apparatus of the present invention includes a reforming unit for obtaining a reformed gas containing hydrogen from a fuel containing at least an organic compound containing water and carbon and water, A CO removal unit that promotes a methanation reaction of at least a part of carbon monoxide contained in the reformed gas and removes at least a part of the carbon monoxide, and is provided in the CO removal unit. Ruthenium is supported on a catalyst part that is at least partly composed of aluminum or an alloy containing aluminum, and alumina that is provided on at least part of the surface of the catalyst part and is anodized on the surface of the catalyst part. And a heating part for heating the temperature of the catalyst part to 250 ° C. or higher.

  In order to achieve the above object, the fuel cell system of the present invention includes a reforming unit for obtaining a reformed gas containing hydrogen from a fuel containing at least an organic compound containing water and carbon and water, A CO removal unit that promotes a methanation reaction of at least a part of carbon monoxide contained in the reformed gas and removes at least a part of the carbon monoxide, and is provided in the CO removal unit. Ruthenium is supported on a catalyst part that is at least partly composed of aluminum or an alloy containing aluminum, and alumina that is provided on at least part of the surface of the catalyst part and is anodized on the surface of the catalyst part. Catalyst layer, a heating part for heating the temperature of the catalyst part to 250 ° C. or higher, a fuel cell that generates power using hydrogen obtained by the reforming reaction and oxygen in the atmosphere , Characterized by having a.

  It is possible to provide a CO removal method, a CO removal apparatus and a production method thereof, a hydrogen generation apparatus using the same, and a fuel cell system using the CO removal method suitable for downsizing.

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

(First embodiment)
FIG. 1 shows a first embodiment of a CO removing apparatus according to the present invention and a fuel cell system using the same.

  The fuel cell system is provided with a hydrogen generator 100 and fuel cells 6.

  The hydrogen generator 100 is provided with a fuel supply means 1. The fuel supply means 1 stores a mixture of water and an organic compound containing carbon and hydrogen that serves as fuel for the fuel cell system. As the fuel, for example, a mixture of dimethyl ether and water, or a mixture of dimethyl ether, water and alcohols can be used. For the alcohols, methanol, ethanol, and the like are preferable, but methanol is particularly preferable because the mutual solubility of dimethyl ether and water is improved.

  As the fuel supply means 1, for example, a pressure vessel detachable from the fuel cell system can be used. The fuel can be sent to the vaporizing section 2 described later using the pressure of dimethyl ether.

  The mixing ratio (molar ratio) of dimethyl ether and water is ideally 1: 3 stoichiometrically. However, in an actual fuel cell system, when the mixing ratio is close to 1: 3, the amount of carbon monoxide produced increases. Furthermore, since the excess water can be used for a shift reaction and power generation described later, it is preferably set to 1: 3.5 or more. However, since the energy at the time of heating and vaporizing the fuel increases in the vaporizing unit 2 described later, the mixing ratio is preferably 1: 5.0 or less, ideally 1: 4.0 or less.

  The hydrogen generator 100 is provided with a vaporization unit 2. The vaporizer 2 is connected to the fuel supply means 1 by piping or the like. The fuel sent to the vaporizing unit 2 is heated and vaporized.

  The hydrogen generator 100 is provided with a reforming unit 3. The reforming unit 3 is connected to the vaporizing unit 2 by piping or the like. The vaporized fuel sent to the reforming unit 3 is reformed by the reforming unit 3 and becomes a gas containing hydrogen (reformed gas). A flow path through which the vaporized fuel passes is provided inside the reforming section 3, and a reforming catalyst for accelerating the reforming reaction of the vaporized fuel to the reformed gas is provided on the inner wall surface of the flow path. Is provided.

  The hydrogen generator 100 can be provided with a CO shift unit 4. The CO shift unit 4 is connected to the reforming unit 3 by piping or the like. The reformed gas reformed by the reforming unit 3 and sent to the CO shift unit 4 includes carbon dioxide and carbon monoxide as by-products in addition to hydrogen. Carbon monoxide degrades the anode catalyst of the fuel cell and causes the power generation performance of the fuel cell system to deteriorate. For this reason, the CO shift unit 4 is provided, and before the gas containing hydrogen is supplied from the reforming unit 3 to the fuel cell 6, the CO shift unit 4 shifts carbon monoxide to carbon dioxide and hydrogen to generate hydrogen. It is preferable to increase the generation amount. A flow path through which the reformed fuel passes is provided inside the CO shift section 4, and a shift for promoting a shift reaction of carbon monoxide contained in the reformed gas is provided on the inner wall surface of the flow path. A catalyst is provided.

  The hydrogen generator 100 is provided with a CO removing unit 5 (CO removing device). The CO removal unit 5 is connected to the CO shift unit 4 by piping or the like. The reformed gas (gas to be removed) that has undergone a shift reaction in the CO shift unit 4 and sent to the CO removal unit 5 still contains 1.0 mol% or less of carbon monoxide. As described above, this causes a decrease in the power generation performance of the fuel cell system. For this reason, before supplying the gas containing hydrogen from the reforming unit 3 to the fuel cell 6, the CO removing unit 5 causes the CO removing unit 5 to perform a methanation reaction that converts carbon monoxide into methane and water. The carbon monoxide is removed until the concentration of carbon monoxide is 100 mol ppm or less. Inside the CO removal unit 5, a catalyst unit 22 for promoting the methanation reaction of carbon monoxide contained in the reformed gas is provided.

  The fuel cell 6 is connected to the CO removing unit 5 by piping or the like. The reformed gas from which carbon monoxide has been removed is sent to the fuel cell 6. The fuel battery cell 6 reacts hydrogen in the reformed gas with oxygen in the atmosphere supplied using the pump 12. Along with the reaction, the fuel cell 6 generates water and generates power. In order to supply air to the fuel battery cell 6, a pump 12 is provided.

  The hydrogen generator 100 is provided with a combustion unit 7 (heating unit). The combustion unit 7 is connected to the fuel cell 6 by piping or the like. In the fuel cell 6, hydrogen and oxygen react to produce water, but the exhaust gas from the fuel cell 6 contains unreacted hydrogen. The combustion unit 7 burns the unreacted hydrogen using atmospheric oxygen supplied using the pump 13.

  At this time, the vaporization unit 2, the reforming unit 3, the CO shift unit 4 and the CO removal unit 5 are heated using combustion heat generated during combustion. The vaporization section 2, the reforming section 3, the CO shift section 4, the CO removal section 5, and the combustion section 7 are heat insulation sections for the purpose of heating efficiency, temperature uniformity, and protection of parts with low heat resistance such as surrounding electronic circuits. 8 is covered. In the reforming unit 3, the heat required for the reforming reaction performed therein is larger than that of the vaporizing unit 2, the CO shift unit 4, and the CO removing unit 5, so that the combustion heat is reformed from the combustion unit 7. It is preferable that the reforming unit 3 and the combustion unit 7 are brought into contact with each other or formed integrally so that they can be efficiently transmitted to the unit 3.

  Next, details of the CO removing unit 5 will be described. FIG. 2 shows an exploded perspective view of the CO removing unit 5. The CO removal unit 5 is provided with a container 21, a catalyst unit 22, and a lid 23.

  The container 21 is formed by processing a base material. In order to improve the heat transfer characteristics during the catalytic reaction, it is preferable to use a material having high thermal conductivity for at least a part of the base material. In particular, aluminum, copper, an aluminum alloy, or a copper alloy is suitable for use as a material of the container 21 because it has not only high thermal conductivity but also excellent workability. Further, when the hydrogen generator is expected to be used for a long period of time, the thermal conductivity is not as high as that of an aluminum alloy or a copper alloy, but a stainless alloy is also preferable because of its excellent corrosion resistance.

  The container 21 is provided with a fitting portion 21 a for fitting the catalyst portion 22. After the catalyst part 22 is fitted, a lid 23 described later is provided. The fitting part 21a is provided so that the flow path is formed by joining the catalyst part 22 and the container 21 as necessary and the container 21 and the lid 23 and sealing the fitting part 21a. . As the shape of the formed flow path, for example, a parallel flow path or a serpentine flow path as shown in FIG. 2 can be used.

  The catalyst portion 22 is formed by processing a base material. The catalyst unit 22 uses aluminum or an alloy containing aluminum as at least a part of the base material.

  The catalyst portion 22 is provided with a through groove 22a. A plurality of through grooves 22 a are provided on one surface of the catalyst portion 22 so that both ends penetrate. The through grooves 22a are provided so as to be adjacent to each other. In order to suppress the variation in temperature of the reformed gas flowing through the through groove 22a, the width of the through groove 22a is preferably 1 mm or less. The through groove 22a is preferably formed by using a general machining method or a molding method for the base material of the catalyst portion 22.

  An example of general machining is electrical discharge machining (wire cutting) using a wire. Wire cutting is a method in which a thin metal wire is used as a tool electrode and electric discharge machining is performed while moving the electrode or workpiece to a target shape. In addition to wire cutting, it is also possible to use abrasive processing by using a blade in which abrasive grains such as diamond are hardened in a disk shape with a resin or the like. In the abrasive processing, the blade moves at high speed while contacting the workpiece, and the locus of the blade is polished and removed by the abrasive to be processed into a desired shape. Wire cutting and abrasive processing are very suitable for processing a groove having both ends penetrated, such as the through groove 22a, in a short time.

  An example of a general molding method is forging. Forging is a processing method in which a tool is applied to a bar or block of metal material to apply a forging effect to improve the mechanical properties of the material and simultaneously form the metal material into a desired shape. In addition to forging, casting can be used. In the casting process, molten metal is poured into a mold having a cavity having a target shape, and after cooling, the mold is removed and processed into a target shape. Forging and casting are very suitable for processing a complicated shape such as the catalyst portion 22.

  A catalyst layer 33 is provided on the wall surface of the through groove 22a. Details of the catalyst layer 33 will be described later.

  The container 21 in which the catalyst unit 22 is fitted is provided with a lid 23. The lid | cover 23 is provided so that the insertion part 21a may be sealed. The lid 23 can be a plate-like member using a material having high thermal conductivity at least in part. Examples of the material having high thermal conductivity include aluminum, copper, an aluminum alloy, and a copper alloy. Further, when the flow channel structure is expected to be used for a long period of time, although the thermal conductivity is not as high as that of an aluminum alloy or a copper alloy, a stainless alloy can also be used because of its excellent corrosion resistance.

  A lid 23 is provided on the container 21 so as to cover an opening portion of the container 21 excluding a supply port 21b and a discharge port 21c described later. A lid 23 provided on the container 21 seals the fitting portion 21a so that a flow path is formed in which the supply port 21b and the discharge port 21c serve as an inlet and an outlet. That is, when the fitting portion 21a is sealed by the lid 23, a flow path is formed so that the fluid supplied from the supply port 21b is discharged from the discharge port 21c after passing through the through groove 22a.

  The container 21 is provided with a supply port 21b and a discharge port 21c so as to communicate with the fitting portion 21a. By sealing the fitting portion 21a into which the catalyst portion 22 is fitted in this way with the lid 23, the CO removal portion 5 having a parallel flow path in which the supply port 21b and the discharge port 21c serve as an inlet and an outlet is formed. The

  As described above, a parallel channel shape or a serpentine shape channel is provided inside the CO removal unit 5. A catalyst layer 33 is provided on the inner wall surface of the flow path.

  The reformed gas subjected to the reforming reaction in the reforming unit 3 and the shift reaction in the CO shift unit and sent to the CO removing unit 5 contains carbon dioxide and carbon monoxide as by-products in addition to hydrogen. As described above, carbon monoxide degrades the anode catalyst of the fuel battery cell and causes power generation performance to deteriorate. For this reason, the CO removal unit 5 uses the CO removal unit 5 to methanate carbon monoxide as shown in the formula (1) before supplying the gas containing hydrogen from the reforming unit 3 to the fuel cell 6. The carbon monoxide is removed until the concentration is 100 ppm or less.

CO + 3H ₂ → CH ₄ + H ₂ O (1)
Details of the catalyst layer 33 will be described. FIG. 3 shows an enlarged part of the cross section of the catalyst layer 33. The catalyst layer 33 has at least ruthenium 32 and, if necessary, other additives supported on the surface of the alumina coating 31. The alumina coating 31 can be formed by anodizing the surface of the aluminum portion of the catalyst portion 22.

  Details of the alumina coating 31 will be described. The catalyst portion 22 is anodized using an acidic aqueous solution or an alkaline aqueous solution to form an alumina film 31 on the surface of the aluminum portion of the catalyst portion 32. Thereafter, if necessary, the fine mouth formed in the alumina film 31 is enlarged using an acidic aqueous solution, and a hydration treatment is performed. Further, the catalyst part 22 is calcined at 350 ° C. or higher for 1 hour or longer, preferably at 450 to 550 ° C., if necessary. The baked alumina film 31 becomes γ-alumina.

  The thickness of the alumina coating 31 is preferably 30 μm or more and 100 μm or less. This is because when the thickness of the alumina coating 31 is less than 30 μm or larger than 100 μm, the utilization efficiency of the catalyst is lowered. In addition, a large number of micropores are present on the surface of the alumina coating 31, but it is preferable that the average pore diameter of the micropores be 5 nm or more and 10 nm or less under the conditions of anodization and subsequent treatment with an acidic aqueous solution. . When the average pore diameter of the micropores is 5 nm or more and 10 nm or less, the selectivity for the methanation reaction of carbon dioxide shown in Formula (2) of the reaction shown in Formula (1) is improved.

CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O (2)
Details of the ruthenium 32 will be described. As described above, the alumina coating 31 has a large number of micropores on its surface. Ruthenium 32 is supported on the alumina film 31 having the fine holes by using a known method such as an impregnation method or a wash coating method.

The impregnation method will be described as an example of known catalyst loading methods. For example the organic salts of ruthenium such as ruthenium acetylacetonate _{(Ru (C 5 H 7 O} 2) 3), for example, acetone _{(CH 3} COCH 3), acetylacetone _{(CH 3} COCH 2 COCH ₃₎ or tetrahydrofuran _((CH 2) _The ruthenium 32 can be impregnated in the alumina coating 31 using an organic solvent such as ₃ CH ₂ O). Further, ruthenium 32 can be impregnated into the alumina film 31 using an aqueous ruthenium chloride solution. However, ruthenium chloride (RuCl ₃ · nH ₂ O) has high acidity, and therefore, the aluminum portion below the alumina film 31 and ruthenium chloride. May react and the alumina coating 31 may peel off. Therefore, when considering the yield and process margin, it is preferable to impregnate the ruthenium 32 into the alumina film 31 using an organic salt of ruthenium and an organic solvent.

  The CO removal conditions of the CO removal unit 5 will be described. The carbon monoxide concentration before removal of the reformed gas that removes carbon monoxide in the CO removal unit 5 is preferably 1.0 mol% or less as described above. Specifically, the reforming unit 3 is provided so as to suppress the generation of carbon monoxide during the reforming reaction or to promote the shift reaction of the carbon monoxide generated during the reforming reaction. Additives can be added to the resulting reforming catalyst. Further, instead of adding the additive to the reforming catalyst or simultaneously with adding the additive to the reforming catalyst, the CO shift unit 4 can be provided as described above.

  Further, the CO removing unit 5 is heated using the combustion unit 7 so that the temperature of the catalyst unit 22 is 250 ° C. or higher. At this time, the temperature of the catalyst unit 22 can be measured by providing a temperature sensor inside the CO removing unit 5. However, as described above, the width of the through groove 22 a provided in the catalyst unit 22 is as small as 1 mm or less, and it may be difficult to provide a temperature sensor inside the CO removal unit 5. In such a case, the temperature of the catalyst unit 22 is indirectly measured by providing a temperature sensor on the outer wall surface of the CO removing unit 5.

  Next, details of the fuel battery cell 6 will be described. The fuel cell 6 includes a fuel electrode 9 made of a porous sheet in which carbon black powder carrying Pt is held by a water-repellent resin binder such as polytetrafluoroethylene (PTFE), and Pt is also carried. Oxidant electrode 10 made of a porous sheet in which the carbon black powder is held with a water-repellent resin binder such as polytetrafluoroethylene (PTFE), and a cation exchange group such as a sulfonic acid group or a carboxylic acid group An electrolyte membrane 11 having proton conductivity made of, for example, Nafion (registered trademark of Du Pont) or the like is sandwiched. This porous sheet may contain a sulfonic acid type perfluorocarbon polymer or fine particles coated with the polymer.

Hydrogen supplied to the fuel electrode 9 is H ₂ → 2H ⁺ + 2e ⁻ (3) at the fuel electrode 9.
It reacts like this. On the other hand, oxygen supplied to the oxidant electrode 10 is ½ O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (4) at the oxidant electrode 10.
It reacts like this.

  Furthermore, the detail of the combustion part 7 is demonstrated. Inside the combustion section 7, for example, a flow path through which fuel used for power generation in a serpentine shape or a parallel flow path shape is provided. The inner wall surface of the flow path is provided with a combustion catalyst such as alumina on which noble metal such as Pt or Pd or Pt and Pd is supported. The reason why the noble metal is used as the combustion catalyst is to prevent the oxidation and deterioration of the combustion catalyst without ancillary equipment for preventing the oxidation and deterioration of the catalyst when the fuel cell is stopped.

  The hydrogen generator and the fuel cell system thus made can sufficiently reduce the concentration of carbon monoxide contained in the reformed gas by the small CO removing unit 5. That is, the hydrogen generator and the fuel cell system can be reduced in size without deteriorating the catalyst of the fuel electrode 9 and reducing the power generation performance.

  Moreover, the selectivity of the methanation of carbon monoxide in the CO removal unit 5 to the methanation of carbon dioxide is high. Therefore, the amount of hydrogen consumed by the methanation reaction of carbon dioxide when removing carbon monoxide in the CO removal unit 5 can be reduced. That is, the hydrogen generation efficiency of the entire hydrogen generator is improved, and the power generation efficiency of the fuel cell system is improved.

  In addition, since the methanation reaction is utilized when removing carbon monoxide in the CO removal unit 5, it is not necessary to supply oxygen to the CO removal unit 5. Therefore, it is not necessary to provide means for supplying oxygen to the CO removing unit 5, such as a pump, and the hydrogen generator and the fuel cell system can be downsized.

  When fuel containing dimethyl ether is used, unmodified dimethyl ether and by-products other than carbon monoxide and carbon dioxide accompanying the reforming reaction of dimethyl ether are anodized even if they are sent to the CO removal section. In addition, the catalyst layer 33 in which ruthenium is supported on alumina is highly resistant to these by-products and can stably remove carbon monoxide for a long time.

  Although the reforming unit 3 has been described with respect to the example in which the reforming catalyst for promoting the reforming reaction of the vaporized fuel to the reformed gas has been described, a mixture of the reforming catalyst and the CO shift catalyst is provided. It doesn't matter. Since the mixture of the reforming catalyst and the CO shift catalyst is provided, the phenomenon that the yield of carbon monoxide on a carbon basis is increased can be reduced.

(Second Embodiment)
FIG. 4 shows a second embodiment of the hydrogen generator and fuel cell system according to the present invention. In addition, the same part as each part of 1st Embodiment shown in FIG. 1 is shown with the same code | symbol, and the description is abbreviate | omitted.

  FIG. 4 illustrates the inside of the CO removing unit 5b. Other configurations are the same as those of the first embodiment. In addition to the combustion unit 7, a heater 41 (heating unit) is provided in the CO removal unit 5b. As the heater 41, for example, a cartridge heater in which a high resistance metal is wound around an insulator can be used. The heater 41 receives energy supply from the outside, for example, electric power when a cartridge heater is used as the heater 41. The electric power supplied to the heater 41 is supplied from, for example, the fuel battery cell 6. The heater 41 supplied with energy from the outside generates heat and heats the CO removing unit 5.

  A plurality of plate-like catalyst portions 42 are provided inside the container 21. The catalyst part 42 uses aluminum or an alloy containing aluminum in at least a part of the base material. The catalyst parts 42 are provided inside the container 21 with gaps, respectively, and the reformed gas supplied from the CO shift part 4 passes between the container 21 or the lid 23 and the catalyst part 42 or between the adjacent catalyst parts 42. Then, the fuel cell 6 is discharged.

  A catalyst layer 33 is provided on the surface of the catalyst portion 42. The detailed description of the catalyst layer 33 and the illustration thereof in FIG. 4 are the same as those in the first embodiment, and will be omitted.

  In the hydrogen generator and the fuel cell system thus formed, the concentration of carbon monoxide contained in the reformed gas can be sufficiently reduced by the small CO removing unit 5b. That is, the hydrogen generator and the fuel cell system can be reduced in size without deteriorating the catalyst of the fuel electrode 9 and reducing the power generation performance.

  In addition, the selectivity of the methanation of carbon monoxide in the CO removal unit 5b to the methanation of carbon dioxide is high. Therefore, the amount of hydrogen consumed by the methanation reaction of carbon dioxide when removing carbon monoxide in the CO removing unit 5b can be reduced. That is, the hydrogen generation efficiency of the entire hydrogen generator is improved, and the power generation efficiency of the fuel cell system is improved.

  In addition, since the CO removal unit 5b uses a methanation reaction to remove carbon monoxide, it is not necessary to supply oxygen to the CO removal unit 5b. Therefore, it is not necessary to provide a means for supplying oxygen to the CO removing unit 5b, such as a pump, and the hydrogen generator and the fuel cell system can be downsized.

  When fuel containing dimethyl ether is used, unmodified dimethyl ether and by-products other than carbon monoxide and carbon dioxide accompanying the reforming reaction of dimethyl ether are anodized even if they are sent to the CO removal section. In addition, the catalyst layer 33 in which ruthenium is supported on alumina is highly resistant to these by-products and can stably remove carbon monoxide for a long time.

  Further, since the heater 41 is provided, the heater 41 can be feedback-controlled. Therefore, the temperature of the CO removing unit 5b can be controlled with higher accuracy, and the concentration of carbon monoxide can be further reduced.

  Further, since the plate-like catalyst portion 42 is provided, the processing of the catalyst portion 42 is less, and the manufacturing costs of the hydrogen generator and the fuel cell system can be reduced. Furthermore, plate-like members provided with other catalysts can be easily combined. For example, even if the reformed gas contains a substance that adversely affects the catalyst portion 42, a plate-like member provided with a catalyst that promotes the conversion of the adversely affected substance into a substance with less influence Can be provided in the CO removing section 5b.

  Although the reforming unit 3 has been described with respect to the example in which the reforming catalyst for promoting the reforming reaction of the vaporized fuel to the reformed gas has been described, a mixture of the reforming catalyst and the CO shift catalyst is provided. It doesn't matter. Since the mixture of the reforming catalyst and the CO shift catalyst is provided, the phenomenon that the yield of carbon monoxide on a carbon basis is increased can be reduced.

(Third embodiment)
FIG. 5 shows a hydrogen generator and a fuel cell system according to a third embodiment of the present invention. In addition, the same part as each part of 1st Embodiment shown in FIG. 1 is shown with the same code | symbol, and the description is abbreviate | omitted.

  FIG. 5 shows an exploded perspective view of the CO removing unit 5. The CO removal unit 5 is provided with a catalyst unit 24 in place of the catalyst unit 22 of the first embodiment. The catalyst part 24 is provided with a catalyst layer 33 on the surface of aluminum having a large number of voids or an alloy containing aluminum and on the surface of the voids. As aluminum having voids or an alloy containing aluminum, for example, an aluminum porous body, foamed aluminum, or aluminum having a honeycomb structure can be used. The detailed description of the catalyst layer 33 and the illustration in FIG. 5 are the same as those in the first embodiment, and will be omitted.

  The catalyst portion 24 can be made of spherical, columnar, plate-like or amorphous aluminum or an alloy containing aluminum. In addition, in FIG. 5, the example using the rectangular parallelepiped catalyst part 24 is shown in figure. The catalyst part 24 is provided in the fitting part 21a. The reformed gas supplied to the CO removing unit 5 flows through the gap of the catalyst unit 24 provided in the fitting unit 21a.

  The hydrogen generator and the fuel cell system thus made can sufficiently reduce the concentration of carbon monoxide contained in the reformed gas by the small CO removing unit 5. That is, the hydrogen generator and the fuel cell system can be reduced in size without deteriorating the catalyst of the fuel electrode 9 and reducing the power generation performance.

  Moreover, the selectivity of the methanation of carbon monoxide in the CO removal unit 5 to the methanation of carbon dioxide is high. Therefore, the amount of hydrogen consumed by the methanation reaction of carbon dioxide when removing carbon monoxide in the CO removal unit 5 can be reduced. That is, the hydrogen generation efficiency of the entire hydrogen generator is improved, and the power generation efficiency of the fuel cell system is improved.

  In addition, since the methanation reaction is utilized when removing carbon monoxide in the CO removal unit 5, it is not necessary to supply oxygen to the CO removal unit 5. Therefore, it is not necessary to provide means for supplying oxygen to the CO removing unit 5, such as a pump, and the hydrogen generator and the fuel cell system can be downsized.

  When fuel containing dimethyl ether is used, unmodified dimethyl ether and by-products other than carbon monoxide and carbon dioxide accompanying the reforming reaction of dimethyl ether are anodized even if they are sent to the CO removal section. In addition, the catalyst layer 33 in which ruthenium is supported on alumina is highly resistant to these by-products and can stably remove carbon monoxide for a long time.

  Moreover, since the catalyst part 24 having a gap is provided, the processing of the catalyst part 24 is less, and the manufacturing cost of the hydrogen generator and the fuel cell system can be reduced. Furthermore, the member which has the space | gap provided with the other catalyst can be combined easily. For example, even if the reformed gas contains a substance that has an adverse effect on the catalyst section 24, a member provided with a catalyst that promotes the conversion of the substance having an adverse effect into another substance having a small influence is added to CO. The removal unit 5 can be provided.

  Although the reforming unit 3 has been described with respect to the example in which the reforming catalyst for promoting the reforming reaction of the vaporized fuel to the reformed gas has been described, a mixture of the reforming catalyst and the CO shift catalyst is provided. It doesn't matter. Since the mixture of the reforming catalyst and the CO shift catalyst is provided, the phenomenon that the yield of carbon monoxide on a carbon basis is increased can be reduced.

  In addition, it should not be understood that the detailed description and drawings of each embodiment limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques are possible for those skilled in the art. In addition, the hydrogen generator and the fuel cell system according to each of the embodiments described in detail can be used for the production and power generation of hydrogen used in various applications. For example, the vaporization unit 2, the CO shift unit 4, and the CO removal unit 5 may be integrally formed. In this case, the thermal resistance between each of the vaporization unit 2 and the CO shift unit 4 and the CO removal unit 5 is reduced, and the amount of hydrogen burned in the combustion unit 7 can be reduced. That is, the hydrogen generation efficiency of the entire hydrogen generator is improved, and the power generation efficiency of the fuel cell system is improved.

  Further, in the present embodiment, the example in which one catalyst unit 22 is provided in the CO removal unit 5 has been described. However, the number of catalyst units 22 provided in the CO removal unit 5 is not limited to one, and for example, two catalyst units 22 may be provided as shown in FIGS. 10 and 11. FIG. 10 is a cross-sectional view of the two catalyst portions 22, and FIG. 11 is an enlarged cross-sectional view in which a part of FIG. When two catalyst parts 22 are provided as shown in FIGS. 10 and 11, the catalyst part 22 can be provided so that the other catalyst part is combined with the through groove 22 a of one catalyst part 22.

  When the two catalyst portions 22 are combined in this way, the pitch of the flow paths formed after the combination can be reduced with respect to the pitch of the through grooves 22a provided in the catalyst portion 22, so that the processing of the catalyst portion 22 is performed. Becomes easy.

Carbon monoxide contained in the reformed gas of the hydrogen generator was removed using the CO removing unit 5 shown in FIG. The container 21, the catalyst part 22, and the lid 23 were made of aluminum. A γ-alumina layer having a thickness of 50 μm was formed on the surface of the catalyst portion 22 to carry ruthenium. Ruthenium acetylacetonate (Ru (C ₅ H ₇ O ₂ ) ₃ ) is used as a ruthenium raw material, soaked in a saturated acetone solution for 24 hours, impregnated, dried at 120 ° C., and calcined at 500 ° C. Thus, the catalyst layer 33 was formed.

  The CO removal unit 5 was supplied with a reformed gas containing carbon dioxide and carbon monoxide in hydrogen to remove carbon monoxide. The temperature of the outer wall surface of the CO removing unit 5 was controlled at 225 ° C., 250 ° C., 275 ° C., and 300 ° C., and the reformed gas after the removal of carbon monoxide at each temperature was analyzed by a gas chromatograph. .

The composition of the reformed gas is H ₂ = 64.0%, CO ₂ = 20.0%, CO = 1.0%, CH ₄ = 5.0%, N ₂ = 10.0%. Here, N ₂ is originally not included in the reformed gas, but is used as an internal standard substance for the convenience of analyzing the reformed gas with a gas chromatograph. The results are shown in FIGS.

  Further, as a comparative example of the conventional hydrogen generator, the same experiment was performed for the following three hydrogen generators.

(Comparative Example 1)
Instead of the catalyst part 22 shown in Example 1, a commercially available ruthenium / γ-alumina catalyst was used. The shape of the catalyst was particulate, and the particulate catalyst was supported on an aluminum through groove having the same shape as the catalyst portion 22 by using a wash coat method.

(Comparative Example 2)
Instead of the catalyst part 22 shown in Example 1, a commercially available ruthenium / γ-alumina catalyst was used. Although it is a ruthenium / γ-alumina catalyst as in Comparative Example 1, it is a different product. The shape of the catalyst was particulate, and the particulate catalyst was supported on an aluminum through groove having the same shape as the catalyst portion 22 by using a wash coat method.

(Comparative Example 3)
Instead of the catalyst part 24 shown in Example 3, a commercially available ruthenium / zeolite catalyst was used. The shape of this catalyst was granular, and this granular catalyst was filled in the fitting portion 21a.

  As shown in FIG. 6, in the hydrogen generators of Comparative Examples 1 to 3, the consumption of hydrogen due to methanation of carbon dioxide increased at 250 ° C. or higher. On the other hand, for the hydrogen generator of Example 1, the amount of hydrogen consumed by methanation of carbon dioxide increases at 250 ° C. or higher, but the amount of hydrogen consumed is significantly less than that of Comparative Examples 1 to 3. I was able to confirm.

  Further, as shown in FIG. 7, in Comparative Example 3, carbon monoxide could be removed up to 250 ° C. until the concentration of carbon monoxide contained in the reformed gas became 100 mol ppm or less. The concentration of carbon monoxide contained in the quality gas has become larger than 100 mol ppm. Regarding the hydrogen generators of Comparative Examples 1 and 2, carbon monoxide could not be removed until the concentration of carbon monoxide contained in the reformed gas was 100 mol ppm or less at any temperature. On the other hand, with respect to the hydrogen generator of Example 1, it was confirmed that carbon monoxide could be removed at 250 ° C. or higher until the concentration of carbon monoxide contained in the reformed gas became 100 mol ppm or lower.

  In addition, about the hydrogen generator shown in Example 1, the reforming | reformation of dimethyl ether was continuously operated on the conditions which generate | occur | produce about 250 cc / min hydrogen gas equivalent to the electric power generation output of 20W output. FIG. 8 shows the change in the concentration of carbon monoxide after the CO removal by the CO removal unit 5 at this time. The molar ratio of dimethyl ether to water at this time was 1: 4.

  As shown in FIG. 8, in the hydrogen generator shown in Comparative Example 3, the concentration of carbon monoxide contained in the reformed gas increased as the operating time passed. On the other hand, it was confirmed that the hydrogen generator shown in Example 1 can stably remove carbon monoxide until the concentration of carbon monoxide contained in the reformed gas becomes 100 mol ppm or less.

  Similarly to Example 1, carbon monoxide contained in the reformed gas of the hydrogen generator was removed using the CO removing unit 5 shown in FIG. The container 21, the catalyst part 22, and the lid 23 were made of aluminum. A γ-alumina layer was formed on the surface of the catalyst portion 22 to carry ruthenium.

  The CO removal unit 5 was supplied with a reformed gas containing carbon dioxide and carbon monoxide in hydrogen to remove carbon monoxide. The temperature of the outer wall surface of the CO removing unit 5 was controlled at 225 ° C., 250 ° C., 275 ° C., and 300 ° C., and the reformed gas after the removal of carbon monoxide at each temperature was analyzed by a gas chromatograph. .

The composition of the reformed gas is H ₂ + CO = 65%, CO ₂ = 20%, CH ₄ = 5%, N ₂ = 10%. The composition of H ₂ and CO is as follows: H ₂ = 62.0% / CO = 3.0%, H ₂ = 64.0% / CO = 1.0%, H ₂ = 64.5% / CO = 0. A reformed gas having 5% and H ₂ = 65.0% / CO = 0% is supplied, and the reformed gas after the removal of carbon monoxide in the composition of each reformed gas is obtained by gas chromatography. analyzed. Here, N ₂ is originally not included in the reformed gas, but is used as an internal standard substance for the convenience of analyzing the reformed gas with a gas chromatograph. The result is shown in FIG.

  As shown in FIG. 9, all of the hydrogen generators supplied with the reformed gas having a carbon monoxide concentration of 1.0% or less had carbon monoxide concentration up to 100 ppm or less at 250 ° C. or higher. I was able to remove it. On the other hand, for the hydrogen generator supplied with the reformed gas having a carbon monoxide concentration of 2.0% and 3.0%, the carbon monoxide could be removed at 300 ° C. until the carbon monoxide concentration was about 100 ppm. However, at 250 ° C., carbon monoxide could not be removed until the concentration of carbon monoxide was about 100 ppm.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows 1st Embodiment of the fuel cell system by this invention. 1 is an exploded perspective view showing a part of a first embodiment of a fuel cell system according to the present invention. 1 is an enlarged sectional view showing a part of a first embodiment of a fuel cell system according to the present invention. The perspective view which shows a part of 2nd Embodiment of the fuel cell system by this invention. The disassembled perspective view which shows a part of 3rd Embodiment of the fuel cell system by this invention. The figure which shows the Example of the fuel cell system by this invention. The figure which shows the Example of the fuel cell system by this invention. The figure which shows the Example of the fuel cell system by this invention. The figure which shows the Example of the fuel cell system by this invention. Sectional drawing which shows a part of modification of embodiment of the fuel cell system by this invention. The expanded sectional view which shows a part of modification of embodiment of the fuel cell system by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel supply means 2 Vaporization part 3 Reforming part 4 CO shift part 5, 5b CO removal part 6 Fuel cell 7 Combustion part 8 Thermal insulation part 9 Fuel electrode 10 Oxidant electrode 11 Electrolyte membrane 12 Pump 13 Pump 21 Containers 22 and 42 Catalyst part 21a Insertion part 21b Supply port 21c Discharge port 22a Through groove 23 Cover 24 Catalyst part 31 Alumina coating 32 Ruthenium 33 Catalyst layer 41 Heater 100 Hydrogen generator

Claims (9)

A CO removal section that promotes a methanation reaction of at least a portion of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen, and removes at least a portion of the carbon monoxide;
A catalyst unit provided in the CO removal unit, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum;
A catalyst layer provided on at least a part of the surface of the catalyst portion, the ruthenium supported on alumina formed by anodizing the surface of the catalyst portion;
A heating unit for heating the temperature of the catalyst unit to 250 ° C. or higher;
CO removal apparatus characterized by having. The catalyst portion is provided with a plurality of through grooves having a width of 1 mm or less adjacent to each other,
The CO removal apparatus according to claim 1, wherein the catalyst layer is provided on a surface of the through groove.   The CO removal apparatus according to claim 1 or 2, wherein the catalyst layer is a catalyst layer in which ruthenium is supported on γ-alumina having an average pore diameter of 5 nm or more and 10 nm or less.   The concentration of carbon monoxide contained in the gas to be removed before at least a part of the carbon monoxide is removed by the CO removing unit is 1.0 mol% or less. The CO removal apparatus according to any one of claims 1 to 3. A CO removal section that promotes a methanation reaction of at least a portion of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen, and removes at least a portion of the carbon monoxide;
A catalyst unit provided in the CO removal unit, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum;
A catalyst layer provided on at least a part of the surface of the catalyst portion, the ruthenium supported on alumina formed by anodizing the surface of the catalyst portion;
A heating unit for heating the temperature of the catalyst unit to 250 ° C. or higher;
A method for manufacturing a CO removal apparatus, comprising:
Forming the alumina by anodizing aluminum or an alloy containing aluminum constituting the CO removal section;
A method for producing a CO removal apparatus, wherein the alumina is impregnated with ruthenium using an organic salt of ruthenium and an organic solvent. A CO removal section that promotes a methanation reaction of at least a portion of carbon monoxide contained in a gas to be removed containing at least carbon monoxide, carbon dioxide, and hydrogen, and removes at least a portion of the carbon monoxide;
A catalyst unit provided in the CO removal unit, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum;
This is a CO removal method using a CO removal device provided on at least a part of the surface of the catalyst part, and having a catalyst layer in which ruthenium is supported on alumina formed by anodizing the surface of the catalyst part. And
A CO removing method, wherein the temperature of the catalyst part is heated to 250 ° C. or higher. A reforming unit for obtaining a reformed gas containing hydrogen from a fuel containing an organic compound containing at least carbon and hydrogen and water;
A CO removal unit that promotes a methanation reaction of at least a portion of carbon monoxide contained in the reformed gas and removes at least a portion of the carbon monoxide;
A catalyst part provided in the CO removal part, at least a part of the surface of which is made of aluminum or an alloy containing aluminum;
A catalyst layer provided on at least a part of the surface of the catalyst portion, the ruthenium supported on alumina formed by anodizing the surface of the catalyst portion;
A heating unit for heating the temperature of the catalyst unit to 250 ° C. or higher;
A hydrogen generator characterized by comprising: A reforming unit for obtaining a reformed gas containing hydrogen from a fuel containing an organic compound containing at least carbon and hydrogen and water;
A CO removal unit that promotes a methanation reaction of at least a portion of carbon monoxide contained in the reformed gas and removes at least a portion of the carbon monoxide;
A catalyst unit provided in the CO removal unit, wherein at least a part of the surface thereof is made of aluminum or an alloy containing aluminum;
A catalyst layer provided on at least a part of the surface of the catalyst portion, the ruthenium supported on alumina formed by anodizing the surface of the catalyst portion;
A heating unit for heating the temperature of the catalyst unit to 250 ° C. or higher;
A fuel cell that generates power using hydrogen obtained by the reforming reaction and oxygen in the atmosphere;
A fuel cell system comprising:   The fuel cell system according to claim 8, wherein the compound is dimethyl ether.

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