JP2008272614A - Co removing catalyst, fuel reforming apparatus, fuel cell system and co removing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CO removing catalyst of a low cost having a high CO removing performance, a fuel reforming apparatus, a fuel cell system and a CO removing device. <P>SOLUTION: In the CO removing catalyst 10A, a copper based catalyst 11 with a diameter of 20 μm and a noble metal based catalyst 14 with a diameter of 20 μm prepared by carrying a noble metal 13 such as Pt on a carrier of an oxide 12 are mixed mechanically in a power state so that a catalyst-distance between the copper based catalyst 11 and the noble metal based catalyst 14 may be maintained properly. Thereby, only a reaction of removing CO can be effectively proceeded to obtain high activity in a wide range of temperature with another reaction such as the oxidation of hydrogen suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a CO removal catalyst, a fuel reformer, a fuel cell system, and a CO removal method with improved CO removal performance.

In recent years, polymer electrolyte fuel cells (PEFC) have low pollution and high thermal efficiency, so that they are expected to be applied as power sources in a wide range of fields such as automobile power supplies and distributed power supplies. This fuel cell system produces hydrogen (H ₂ ) by reforming a hydrocarbon-based fuel (city gas, methane, provan, kerosene, dimethyl ether, etc.) with a reformer. However, the reformed gas reformed by the reformer contains carbon monoxide (CO) and carbon dioxide (CO ₂ ) in addition to hydrogen (H ₂ ), and the carbon monoxide (CO) Platinum, which is mainly used as an electrode catalyst for fuel cells, is poisoned. Therefore, a method of reducing the concentration of carbon monoxide (CO) contained in the resulting gas by performing an oxidation reaction of carbon monoxide (CO) with a CO removal catalyst provided in the CO removal apparatus is taken. Yes.

  In order to prevent poisoning of the polymer electrolyte fuel cell electrode, it is necessary to stably reduce the concentration of carbon monoxide (CO) to 50 ppm or less, preferably 20 ppm or less, and further 10 ppm or less. Therefore, high selectivity and reactivity are required for the CO removal catalyst.

FIG. 9 is a relational diagram showing the relationship between the temperature and CO concentration of a noble metal catalyst, a copper catalyst, and a catalyst in which the copper catalyst and the noble metal catalyst are separately arranged.
As shown in FIG. 9, for example, a noble metal catalyst using a noble metal such as platinum (Pt) has a high activity in a wide temperature range compared to a copper catalyst or a catalyst in which a copper catalyst and a noble metal catalyst are separately arranged. As shown, the concentration of carbon monoxide (CO) can be stably reduced to 10 ppm or less, for example, when the temperature (° C.) of the catalyst layer is in the range of 80 to 160 ° C., for example. Therefore, a noble metal catalyst using a noble metal such as platinum (Pt) has been conventionally used as a CO removal catalyst (Patent Document 1).

  In addition, Japanese Patent Application No. 2005-173567 proposes a method of separating and arranging a copper-based catalyst and a noble metal-based catalyst as a catalyst that replaces the noble metal-based catalyst, thereby reducing costs by reducing the amount of expensive noble metal used. In addition, it has been proposed to use a catalyst that reduces the concentration of carbon monoxide (CO) to a predetermined reference value or less.

JP 2002-273223 A

  However, since noble metal catalysts using noble metals such as platinum (Pt) and ruthenium (Ru) are expensive, the cost becomes high. When these noble metal catalysts are used in a polymer electrolyte fuel cell (PEFC) system, There is a problem that it is difficult to reduce the cost of the polymer fuel cell (PEFC) system.

  In addition, the base metal catalyst of the Cu-based catalyst that uses Cu as the catalyst component in place of the noble metal-based catalyst as the CO removal catalyst is low in cost, but has high selectivity and reactivity that sufficiently reduce the carbon monoxide (CO) concentration. Therefore, it is difficult to use as a CO removal catalyst.

  In addition, a catalyst in which a copper catalyst and a noble metal catalyst are dividedly arranged in place of a noble metal catalyst as a CO removal catalyst is a carbon monoxide (CO) only when the temperature (° C.) of the catalyst layer is, for example, a narrow range of 100 to 110 ° C. ) Cannot be reduced to, for example, 10 ppm or less, and there is a problem that the temperature range in which the carbon monoxide (CO) concentration is below a predetermined reference value is narrower than that of a noble metal catalyst.

Moreover, in the said CO removal catalyst, the oxidation reaction of carbon monoxide (CO) is advanced like Formula (I) below by blowing air together with the reformed gas.
At the same time, carbon monoxide (CO) reacts with hydrogen (H ₂ ) to advance the methanation (CH ₄ ) reaction of carbon monoxide (CO) as shown in the following formula (II).
CO + 1 / 2O ₂ → CO ₂ (I)
CO + 3H ₂ → CH ₄ + H ₂ O (II)

The oxidation reaction of carbon monoxide (CO) as in the above formula (I) and the methanation (CH ₄ ) reaction of carbon monoxide (CO) as in the above formula (II) are exothermic reactions, and temperature control is difficult. Therefore, assuming a daily start up and shut down (DSS) operation, the CO removal catalyst is sensitive to the temperature environment, so it is convenient in an unsteady state that involves raising and lowering the temperature of the catalyst layer. There is a problem that sex is not enough.

  In view of the above problems, an object of the present invention is to provide a CO removal catalyst, a fuel reformer, a fuel cell system, and a CO removal method having low cost and high CO removal performance.

  A first invention of the present invention for solving the above-mentioned problem is a CO removal catalyst that selectively oxidizes and removes carbon monoxide in a gas, comprising at least one copper-based catalyst or noble metal-based catalyst. One of these is a CO removal catalyst characterized in that any one of them is mechanically mixed and combined in a powder state.

  A second invention is the CO removal catalyst according to the first invention, wherein the weight ratio of the noble metal in the noble metal catalyst is 0.05% or less of the total weight of the catalyst.

  A third invention is the first or second invention, wherein the copper-based catalyst carries an active component composed of metallic copper or copper oxide and the active component, and includes aluminum oxide, cerium oxide, zirconium oxide, CO removal catalyst characterized by comprising a support comprising at least one oxide of zinc oxide, lead oxide, manganese oxide, nickel oxide, titanium oxide, iron oxide, vanadium oxide, cobalt oxide, chromium oxide, and metal silicate It is in.

  A fourth invention is the CO removal according to any one of the first to third inventions, wherein the copper-based catalyst is a perovskite complex oxide containing the copper or the copper oxide as an active component. In the catalyst.

  According to a fifth invention, there is provided a CO removal catalyst characterized in that the CO removal catalyst according to any one of the first to fourth inventions has DSS durability.

  According to a sixth aspect of the present invention, there is provided a fuel reforming catalyst device for reforming a hydrocarbon-based raw fuel for a fuel cell into a reformed gas, a CO converting device for transforming carbon monoxide generated in the fuel reforming catalyst device, The fuel reforming apparatus comprises a CO removing device that removes residual carbon monoxide with the CO removing catalyst according to any one of the first to fifth inventions to form a fuel gas.

  According to a seventh aspect of the present invention, there is provided a fuel cell system for a fuel cell comprising the fuel reformer of the sixth aspect of the present invention and a fuel cell that generates electric power using a gas converted from carbon monoxide.

  When removing carbon monoxide remaining in the reformed gas obtained by reforming a hydrocarbon-based raw fuel for a fuel cell, the eighth invention provides at least one copper-based catalyst or noble metal-based catalyst as a CO removal catalyst. A CO removal method is characterized in that carbon monoxide remaining in the reformed gas is removed using a catalyst obtained by mixing any of the catalysts.

  A ninth invention is the CO removal method according to the eighth invention, wherein a weight ratio of the noble metal of the noble metal catalyst is 0.05% or less of a weight of the whole catalyst.

  A tenth invention is the eighth or ninth invention, wherein the copper-based catalyst carries an active component composed of metallic copper or copper oxide and the active component, and comprises aluminum oxide, cerium oxide, zirconium oxide, A CO removal method comprising: a carrier comprising at least one oxide of zinc oxide, lead oxide, manganese oxide, nickel oxide, titanium oxide, iron oxide, vanadium oxide, cobalt oxide, chromium oxide, and metal silicate. It is in.

  An eleventh invention is the CO removal according to any one of the eighth to tenth inventions, wherein the copper-based catalyst is a perovskite complex oxide containing copper or the copper oxide as an active component. Is in the way.

  According to the present invention, the catalyst activity and the heat resistance can be improved by using a catalyst obtained by mixing and combining at least one or more kinds of copper-based catalyst or noble metal-based catalyst. And CO removal performance can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment and an Example. In addition, constituent elements in the following embodiments and examples include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[First embodiment]
The CO removal catalyst according to the present embodiment is a CO removal catalyst that selectively oxidizes and removes carbon monoxide in a gas, and is a mixture of a single type of copper catalyst and a noble metal catalyst. is there.

FIG. 1 is a schematic configuration diagram showing a state of a CO removal catalyst obtained by mechanically mixing the copper catalyst and the noble metal catalyst in a powder state.
As shown in FIG. 1, a CO removal catalyst 10A according to this embodiment includes a copper catalyst 11 having a diameter of 20 μm, for example, and a noble metal having a diameter of 20 μm in which a noble metal 13 such as Pt is supported on an oxide 12 carrier. The inter-catalyst distance between the copper catalyst 11 and the noble metal catalyst 14 can be kept moderate by mechanically mixing the system catalyst 14 in a powder state.

Here, for example, as a method of mixing the copper-based catalyst 11 and the noble metal 13, the copper-based catalyst 11 and platinum prepared by a conventional method of impregnating the copper-based catalyst 11 with a platinum (Pt) salt solution. In the catalyst in which the noble metal 13 such as (Pt) is mixed, as shown in FIG. 2, for example, a catalyst in which the noble metal 13 is in close contact with the copper-based catalyst 11 is formed. At this time, if the distance between the copper-based catalyst 11 and the noble metal 13 is short, the oxidation of hydrogen may progress as shown in the following formula (III).
H ₂ + 1 / 2O ₂ → H ₂ O (III)

On the other hand, a CO removal catalyst 10A formed by mechanically mixing the copper catalyst 11 and the noble metal catalyst 14 as shown in FIG. 1 is between the copper catalyst 11 and the noble metal catalyst 14. By keeping the inter-catalyst distance moderately, the oxidation of carbon monoxide (CO) can be preferentially advanced as shown in the following formula (IV).
CO + 1 / 2O ₂ → CO ₂ (IV)

FIG. 3 is a relationship diagram showing the relationship between the temperature of the CO removal catalyst 10A according to this embodiment and the CO concentration.
As shown in FIG. 3, the copper-based catalyst 11 and the noble metal-based catalyst 14 are mechanically mixed in a powder state, whereby the minimum removal peak temperature of the copper-based catalyst and the noble metal-based catalyst 14 shown in FIG. It has a minimum removal peak temperature different from the minimum removal peak temperature.

  Further, the CO removal catalyst 10A obtained by mechanically mixing the copper-based catalyst 11 and the noble metal-based catalyst 14 in a powder state is simply more than the catalyst in which the copper-based catalyst 11 and the noble metal-based catalyst 14 are separately disposed. Since the CO concentration (ppm) is, for example, 10 ppm or less over a wide temperature range, it can be confirmed that the activity of the CO removal catalyst 10A according to this embodiment is improved and the CO removal performance is improved.

  Therefore, since the copper-based catalyst 11 and the noble metal-based catalyst 14 are mechanically mixed in a powder state, a high activity close to that of the noble metal-based catalyst 14 can be obtained. Therefore, a predetermined reference value (for example, 10 ppm) The concentration (ppm) of carbon monoxide (CO) can be suppressed below.

Further, by mechanically mixing the copper-based catalyst 11 and the noble metal-based catalyst 14 in a powder state, the carbon monoxide (CO) is reduced to a predetermined reference value (for example, 10 ppm) or less that exhibits high activity in a wide temperature range. Since the concentration (ppm) of the catalyst can be suppressed, when DSS operation is assumed, even in an unsteady state that involves raising and lowering the temperature of the catalyst layer, it is stably oxidized to a predetermined reference value (for example, 10 ppm) or less. The concentration (ppm) of carbon (CO) can be suppressed.
In other words, in the present invention, the CO removal catalyst having DSS durability refers to a CO shift catalyst having CO removal performance even in an unsteady state in which the temperature of the catalyst layer is raised or lowered.

  Here, DSS operation refers to an operation method that normally starts and stops once a day, such as stopping at night when there is little power consumption and starting in the early morning. The present invention is not limited, and includes an operation that frequently starts and stops and a method that appropriately starts and stops, and is effective in either case.

  As described above, the copper-based catalyst 11 and the noble metal-based catalyst 14 are mechanically mixed in a powder state, so that the copper-based catalyst 11 and the noble metal-based catalyst 14 are simply separated and arranged. A synergistic effect of the copper-based catalyst 11 and the noble metal-based catalyst 14 can be obtained.

  Thereby, the CO removal catalyst 10A obtained by mechanically mixing the copper catalyst 11 and the noble metal catalyst 14 has an appropriate inter-catalyst distance between the copper catalyst 11 and the noble metal catalyst 14. Therefore, only the carbon monoxide (CO) removal reaction can proceed effectively by suppressing other reactions such as hydrogen oxidation, and high activity can be achieved over a wide temperature range. Obtainable.

  Moreover, in this embodiment, it is preferable that the weight ratio of the noble metal of the noble metal catalyst is 0.05% or less of the total weight of the catalyst. This is because if it exceeds 0.05%, the cost of the catalyst becomes high, while if it is too small, the catalytic activity is lowered and both are not preferable.

  Therefore, since the CO removal catalyst 10A according to the present embodiment greatly reduces the content of the noble metal, the cost of the CO removal catalyst can be reduced.

  Further, in this embodiment, a CO removal catalyst obtained by mechanically mixing the copper-based catalyst and the noble metal-based catalyst in a powder state is used. However, the present invention is not limited to this, for example, Any one of at least one copper-based catalyst or noble metal-based catalyst may be mixed and combined.

  The copper catalyst 11 carries an active component composed of metallic copper or copper oxide and the active component, and includes aluminum oxide, cerium oxide, zirconium oxide, zinc oxide, lead oxide, manganese oxide, nickel oxide, This refers to a catalyst comprising a carrier comprising at least one oxide of titanium oxide, iron oxide, vanadium oxide, cobalt oxide, chromium oxide, and metal silicate.

  The copper-based catalyst 11 may be a perovskite complex oxide containing copper or the copper oxide as an active component.

  By using a perovskite-type composite oxide as the copper-based catalyst, copper is taken into the perovskite crystal structure and is not reduced even during the removal of carbon monoxide (CO), so that carbon monoxide is stably present. (CO) can be removed. In addition, since the active species is stably supported in the perovskite crystal structure, the life of the catalyst can be extended.

  The noble metal 13 is any one of gold, platinum, ruthenium, palladium and rhodium or a mixture thereof.

  Further, as the carrier for supporting the noble metal catalyst 14, a heat-resistant carrier such as alumina, zirconia, or silica is preferable. Furthermore, for example, a composite oxide such as alumina-silica or alumina-zirconia may be used.

  Further, the CO removal catalyst according to the present embodiment can be used as a CO removal catalyst in the DSS operation of the fuel cell, but the present invention is not limited to this, for example, an operation that frequently starts and stops or an appropriate start-up. It can also be used for operation that stops.

[Second Embodiment]
The CO removal catalyst according to the present invention is a CO removal catalyst that selectively oxidizes and removes carbon monoxide in a gas, and is formed by mechanically mixing two types of copper-based catalysts in a powder state. is there.

FIG. 4 is a relationship diagram showing the relationship between the temperature and the CO concentration of the CO removal catalyst according to this embodiment.
As shown in FIG. 4, the CO removal catalyst 10B according to this embodiment includes two types of copper-based catalysts, a perovskite-type composite oxide 11-1 and a copper-based catalyst 11-2 formed by supporting the copper on the support. It is a catalyst formed by mechanically mixing the catalyst 11 in a powder state. By mechanically mixing two kinds of copper-based catalysts 11 of the perovskite-type composite oxide 11-1 and the copper-based catalyst 11-2 in a powder state like the CO removal catalyst 10B according to the present embodiment. Since the activity of the catalyst can be improved as compared with the catalyst consisting only of the copper-based catalyst shown in FIG. 9, the carbon monoxide (CO) concentration can be reduced.

  Further, the CO removal catalyst 10B according to the present embodiment includes carbon monoxide (such as a catalyst obtained by mechanically mixing the copper catalyst 11 and the noble metal catalyst 14 in a powder state or the noble metal catalyst 14). The CO) concentration can be reduced to a reference value (for example, 10 ppm) or less.

  Therefore, the perovskite-type composite oxide 11-1 and the copper-type catalyst 11-2 are mechanically mixed in a powder state to form the perovskite-type composite oxide 11-1 and the copper-based catalyst 11-2. Since the synergistic effect by two types of copper catalysts with the copper catalyst 11-2 can be obtained, the activity of the catalyst can be improved as compared with a catalyst consisting of only one type of copper catalyst.

[Third embodiment]
A fuel reformer according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a schematic diagram showing the configuration of the fuel reformer used in the present embodiment. As shown in FIG. 5, the fuel reformer 20 according to this embodiment includes a fuel reforming catalyst device 23 that reforms a hydrocarbon-based raw fuel 21 for a fuel cell into a reformed gas 22, and the fuel reformer. CO conversion device 24 that converts carbon monoxide (CO) generated in the carbonaceous catalyst device 23, and CO removal catalyst 10 according to the present invention to remove residual carbon monoxide (CO) to form a fuel gas 25 And the device 26.

  When the fuel reformer 20 according to the present invention uses, for example, city gas (main component of methane) or LPG (main component of propane) as the raw fuel 21, a sulfur component (S component) that is an odor component is firstly used. Remove.

Next, the reformed catalyst of the fuel reforming catalyst device 23 is caused to react by the following formula (V) at about 700 ° C. to obtain the reformed gas 22 containing hydrogen.
CH ₄ + H ₂ O → CO + 3H ₂ or C ₃ H ₈ + 3H ₂ O → 3CO + 7H ₂ (V)

The reformed gas 22 thus obtained contains a large amount of carbon monoxide (CO), and this carbon monoxide (CO) acts as a poisoning substance that inhibits the electrode of the fuel cell. Therefore, a shift reaction is caused at about 200 to 450 ° C. in the subsequent CO conversion device 24 to convert carbon monoxide (CO) to carbon dioxide (CO ₂ ).

  Carbon monoxide (CO) is usually reduced and removed to about 3000 to 4000 ppm from the reformed gas 22 that has passed through the CO converter 24, but the fuel gas 25 introduced into the fuel cell body is usually 50 ppm. In the following, it is necessary that the CO concentration is preferably 20 ppm or less. If the carbon monoxide (CO) concentration is kept as it is, the battery is poisoned. Therefore, the carbon removal device 26 having the CO removal catalyst 10 according to the present invention is provided in the downstream of the CO conversion device 24 to further remove carbon monoxide (CO).

  In the CO removing device 26, 3000 to 4000 ppm of carbon monoxide (CO) in the gas is subjected to a catalytic reaction for further reduction. Thereby, the carbon monoxide (CO) concentration is reduced, and the carbon monoxide (CO) concentration is reduced to about 10 to 50 ppm or 10 ppm or less.

  The fuel reforming apparatus according to the third embodiment of the present invention improves CO removal performance by using a CO removal catalyst that is a mixture of at least one copper catalyst or noble metal catalyst. And an advantage that the CO removal temperature range can be expanded.

[Fourth embodiment]
Next, a fuel cell system using the fuel reformer of the present invention will be described with reference to FIG.
FIG. 6 is a conceptual diagram showing a PEFC type fuel cell system. Since the configuration of the fuel reformer is the same as that of the fuel reformer according to the third embodiment of the present invention, the description thereof is omitted here.

  As shown in FIG. 6, a power generation system (PEFC power generation system) 1000 for a PEFC type fuel cell according to the embodiment includes a fuel electrode 1002-1 that supplies a fuel gas 1001, and an air electrode 1002-2 that supplies air 1003. The fuel cell 1002 including the cooling unit 1002-3 that supplies the refrigerant 1004 and removes the heat generated by the electrochemical reaction during operation, and the fuel gas 1001 supplied to the fuel electrode 1002-1 are modified from the raw fuel 1005. And a fuel reformer 1006 for generating the electric power, and the electric power is generated by the fuel supplied to the fuel electrode 1002-1 to obtain the DC power 1020 from the fuel cell 1002. This power generation system 1000 is configured to fully automatically start, generate, stop, and alarm / protect a fuel cell by a control system (not shown).

  As the raw fuel 1005 by the reformer, for example, city gas, LPG gas, kerosene, or the like is used, and a desulfurizer 1007 is installed for removing sulfides.

The raw fuel 1005 is reformed by a fuel reformer 1006. Here, the reforming of the raw fuel 1005 is mainly performed by a steam reforming reaction in a reforming catalyst (not shown) of the fuel reforming catalyst device 1006-1A of the fuel reforming device 1006. That is, the raw fuel 1005 and the steam 1009 are mixed and circulated through the reforming catalyst layer, and the steam reforming reaction (for example, city gas is used) at a temperature of, for example, 700 to 800 ° C. using the reformer burner 1006-1B. In some cases, CH ₄ + H ₂ O → CO + 3H ₂ ) is caused. Examples of the reforming catalyst include Ru / Al ₂ O _3, but are not limited thereto. The reformed reformed gas 1008 then passes through the CO conversion device 1006-2 and the above-described CO removal device 1006-3 to become the fuel gas 1001. Examples of the CO removal catalyst in the CO removal apparatus 1006-3 include a catalyst obtained by mixing and combining at least one of a copper catalyst and a noble metal catalyst.

  The cooling line L1 of the refrigerant 1004 is provided with a heat radiating portion 1010 that exchanges heat, for example, water or air, and radiates heat when heat is generated in the fuel cell power generation. Further, in the present system, various heat sources such as the heat radiating portion 1010 are used by utilizing heat generated accompanying the fuel cell reaction.

  In the system of FIG. 6, when fuel cell power generation is started, the raw fuel 1005 is supplied to the reformer burner 1006-1B to raise the temperature of the fuel reforming catalyst device 1006-1A to perform steam reforming. After setting to a suitable predetermined temperature condition, the raw fuel 1005 is supplied to obtain the reformed gas 1008. Thereafter, the obtained reformed gas 1008 is converted into a fuel gas 1001 from which CO has been removed through a CO conversion device 1006-2 and a CO removal device 1006-3, and is supplied to the fuel electrode 1002-1 to start power generation. The The exhaust gas from the fuel electrode 1002-1 is sent to the reformer burner 1006-1B and burned there to use unreacted gas.

  In the power generation system of the present PEFC type fuel cell, the CO removal device 1006-3 uses, as the CO removal catalyst, a catalyst or the like obtained by mixing and combining at least one kind of copper catalyst or noble metal catalyst. Therefore, CO can be removed at low cost over a long period of time, so that a fuel gas with reduced CO can be stably obtained, and a fuel cell system that is stable and reliable over a long period of time is provided. can do.

  Examples illustrating the effects of the present invention will be described below, but the present invention is not limited thereto.

[Method for preparing catalyst]
First, a method for preparing the copper-based catalyst powder and the noble metal-based catalyst powder used in this example will be described.
Thereafter, Examples 1-1 to 1-5 using the catalysts 1 to 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder, and the comparative catalyst 1 including only the noble metal-based catalyst powder. Evaluation results of Comparative Example 1-1 using Comparative Example 1-1 using Comparative Example 2 and Comparative Catalyst 2 consisting only of the copper-based catalyst powder will be described.

A method for preparing the copper-based catalyst powder used in this example will be described.
First, 90 g (0.52 mol) of selenium oxide (CeO ₂ ) powder having a specific surface area of 140 m ² / g in a magnetic dish was dispersed in 500 cc of distilled water to form a slurry. To this, 37.9 g of copper nitrate trihydrate (Cu (NO ₃ ) ₂ .3H ₂ O) was taken, a solution dissolved in 100 cc of distilled water was added, and water was removed with a 120 ° C. plate while stirring. After drying, the mixture was pulverized into a lump in a mortar and calcined in the atmosphere at 300 ° C. for 3 hours to obtain a catalyst powder of selenium oxide (23 mol% Cu / CeO ₂ ) carrying 23 mol% of copper used in the catalyst 1. This catalyst powder was also used in Comparative Catalyst 2.

Γ-alumina (γ-Al ₂ O ₃ ) instead of selenium oxide (CeO ₂ ) used in the preparation of catalyst powder of selenium oxide (23 mol% Cu / CeO ₂ ) carrying 23 mol% of copper used in catalyst 1 The copper nitrate trihydrate (Cu (NO ₃ ) ₂ .3H ₂ O) was changed to 57 g. Other catalyst powder preparation methods were carried out in the same manner as the method for preparing the catalyst powder of selenium oxide (Cu / CeO ₂ ) supporting 23 mol% of copper used for the catalyst 1 described above, and supporting 23 mol% of copper used for the catalyst 2. A catalyst powder of γ-alumina (23 mol% Cu / γ-Al ₂ O ₃ ) was obtained.

In a magnetic dish, weigh lanthanum nitrate hexahydrate, manganese nitrate (Mn (NO ₃ ) ₂ ), and copper nitrate (Cu (NO ₃ ) ₂ ) in an ideal ratio (stoichiometric ratio) and add to distilled water. After dissolution, the mixture was ignited on a 200 ° C. plate and evaporated to dryness. After drying, the mixture is pulverized into a lump in a mortar and baked in the atmosphere at 850 ° C. for 3 hours, so that the perovskite complex oxide (LaMn _0.8 Cu _0.2 O ₃ , CuMn ₂ O ₄₎ supporting copper used for the catalysts 3 to 5 , LaCuO ₄ ) catalyst powder was obtained.

Next, a method for preparing a catalyst powder of a noble metal catalyst used in this example will be described.
Chloroplatinic acid solution (H ₂ (PtCl ₆ ) · 6H ₂ O) weighed to a predetermined molar ratio with 95 g of α-alumina (α-Al ₂ O ₃ ) powder in 350 cc of distilled water in a magnetic dish The water was removed with a 120 ° C. plate while mixing. After drying, the catalyst powder of α-alumina (1 mol% Pt / α-Al ₂ O ₃ ) supporting 1 mol% of platinum used in the catalyst 1 by pulverizing into a lump in a mortar and firing in the atmosphere at 500 ° C. for 3 hours. Got. This catalyst powder was also used in Comparative Catalyst 1.

Instead of α-alumina (α-Al ₂ O ₃ ) used in the preparation of the catalyst powder of α-alumina (1 mol% Pt / α-Al ₂ O ₃ ) supporting 1 mol% of platinum used in catalyst 1, -Alumina (γ-Al ₂ O ₃ ) was used and changed to a ruthenium nitrate solution instead of the chloroplatinic acid solution (H ₂ (PtCl ₆ ) · 6H ₂ O). The other catalyst powders were prepared in the same manner as in the preparation of the catalyst powder of α-alumina (1 mol% Pt / α-Al ₂ O ₃ ) carrying 1 mol% of platinum used in the catalyst 1 described above. Catalyst powder of γ-alumina (2 mol% Ru / γ-Al ₂ O ₃ ) carrying 2 mol% of ruthenium used in the above was obtained.

Further, the method for preparing the catalyst powder of γ-alumina (0.5 mol% Pt + 1 mol% Ru / γ-Al ₂ O ₃ ) supporting 0.5 mol% of platinum and 1 mol% of ruthenium used for the catalyst 3 is all described above. Catalyst powder of α-alumina (1 mol% Pt / α-Al ₂ O ₃ ) supporting 1 mol% of platinum used for catalyst 1 and γ-alumina (2 mol% Ru / γ-Al) supporting 2 mol% of ruthenium used for catalyst 2 ₂ O ₃ ) in the same manner as the catalyst powder preparation method, and γ-alumina (0.5 mol% Pt + 1 mol% Ru / γ-Al ₂ O ₃₎ supporting 0.5 mol% of platinum and 1 mol% of ruthenium used for the catalyst ₃ ) Catalyst powder was obtained.

Further, with respect to a method for preparing a catalyst powder of α-alumina (0.5 mol% Pt / α-Al ₂ O ₃ ) carrying 0.5 mol% of platinum used for the catalyst 4, 2 mol% of ruthenium used for the catalyst 2 was carried. α-alumina (0.5 mol% Pt / α-) carrying 0.5 mol% of platinum used in the catalyst 4 was prepared in the same manner as the preparation method of the catalyst powder of γ-alumina (2 mol% Ru / γ-Al ₂ O ₃ ). A catalyst powder of Al ₂ O ₃ ) was obtained.

In addition, as a method for preparing a catalyst powder of γ-alumina (1 mol% Ru / γ-Al ₂ O ₃ ) supporting 1 mol% of ruthenium used for the catalyst 5, α-alumina supporting 1 mol% of platinum used for the catalyst 1 ( The catalyst powder of γ-alumina (1 mol% Ru / γ-Al ₂ O ₃ ) carrying 1 mol% of ruthenium used for the catalyst 5 is obtained in the same manner as the preparation method of the catalyst powder of Pt / α-Al ₂ O ₃ ). It was.

Catalyst 1 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder is a catalyst powder of selenium oxide (23 mol% Cu / CeO ₂ ) supporting 23 mol% of copper, and α supporting 1 mol% of platinum. A catalyst obtained by mixing alumina (1 mol% Pt / α-Al ₂ O ₃ ) catalyst powder.
The platinum weight ratio of the noble metal catalyst powder at this time was 0.05% of the total weight of the catalyst.

The catalyst 2 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder is a catalyst powder of γ-alumina (23 mol% Cu / γ-Al ₂ O ₃ ) supporting 23 mol% of copper, This is a catalyst obtained by mixing a catalyst powder of γ-alumina (2 mol% Ru / γ-Al ₂ O ₃ ) carrying 2 mol% of ruthenium.
At this time, the weight ratio of ruthenium in the noble metal catalyst powder was 0.03% of the total weight of the catalyst.

Catalyst 3 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder is a perovskite complex oxide (LaMn _0.8 Cu _0.2 O ₃ ) supporting copper, 0.5 mol% of platinum and ruthenium. It is a catalyst obtained by mixing 1 mol% of supported γ-alumina (0.5 mol% Pt + 1 mol% Ru / γ-Al ₂ O ₃ ) catalyst powder.
The weight ratio of platinum and ruthenium in the noble metal catalyst powder at this time was 0.02% of the total weight of the catalyst.

The catalyst 4 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder is a perovskite-type composite oxide (CuMn ₂ O ₄ ) supporting copper and α-alumina supporting 0.5 mol% of platinum. It is a catalyst obtained by mixing (0.5 mol% Pt / α-Al ₂ O ₃ ) catalyst powder.
The platinum weight ratio of the noble metal catalyst powder at this time was 0.05% of the total weight of the catalyst.

Catalyst 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder is a perovskite-type composite oxide (LaCuO ₄ ) supporting copper and γ-alumina (1 mol% Ru supporting 1 mol% ruthenium). / Γ-Al ₂ O ₃ ) catalyst powder.
The weight ratio of ruthenium in the noble metal catalyst powder at this time was 0.03 (%) of the total weight of the catalyst.

The comparative catalyst 1 made of only the noble metal catalyst powder is a catalyst made of only α-alumina (1 mol% Pt / α-AAl ₂ O ₃ ) catalyst powder carrying 1 mol% of platinum.
At this time, the weight ratio of platinum in the noble metal catalyst powder was 1.0% of the total weight of the catalyst.

The comparative catalyst 2 composed only of the copper-based catalyst powder is a catalyst composed only of catalyst powder of selenium oxide (23 mol% Cu / CeO ₂ ) carrying 23 mol% of copper.

  As for the catalyst mixing method, a predetermined amount of the copper-based catalyst powder and the noble metal-based catalyst powder obtained by the adjustment method described above are mixed in an agate mortar and pressed into a 3 mm average spherical shape with a 30-ton press. Molded and mechanically mixed to obtain a catalyst.

  As described above, the catalyst 1 to the catalyst 5 prepared by mixing the copper-based catalyst powder prepared as described above and the noble metal-based catalyst powder, the comparative catalyst 1 including only the noble metal-based catalyst powder, and the copper-based catalyst. The results of summarizing the composition of the catalyst of Comparative Catalyst 2 consisting only of powder are shown in Table 1 below.

  Next, the catalyst 1 to catalyst 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder in this example, the comparative catalyst 1 consisting of only the noble metal-based catalyst powder, and the copper-based catalyst powder The catalyst performance with the comparative catalyst 2 consisting only of was evaluated.

  35 cc of catalyst was filled in a tubular reaction tube having an inner diameter of 30 mm, and the catalyst performance was evaluated. The catalyst performance was evaluated by the absolute value of the carbon monoxide (CO) concentration (ppm) using an infrared detector type CO concentration analyzer. The gas composition and flow rate were controlled by a mass flow controller, and the catalyst layer temperature was controlled by an electric furnace.

[Reaction conditions]
For verification of catalyst 1 to catalyst 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder, the comparative catalyst 1 composed only of the noble metal-based catalyst powder, and the comparative catalyst 2 composed solely of the copper-based catalyst powder. As reaction conditions used, reaction temperature (° C.), pressure (MPa), GHSV (Gas Hourly Space Velocity) (h ⁻¹ ), gas composition (vol% -DRY), oxygen supplied to the catalyst layer (O Table 2 below shows the ratio (O ₂ / CO) of carbon monoxide (CO) to oxygen (O ₂ ) in the gas containing ₂ ).

[Catalyst performance]
Examples 1-1 to 1-5 using the catalysts 1 to 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder and the comparative catalyst 1 including only the noble metal-based catalyst powder are used. As the catalyst performance of Comparative Example 1-1 and Comparative Example 1-2 using Comparative Catalyst 2 made of only the copper-based catalyst powder, the outlet CO concentration (ppm) was measured under the conditions shown in Table 2 above. The CO removal performance of the catalyst was evaluated.
The reaction temperature (° C.) was 100, 120, 150, 170, 200, and 230 ° C., respectively.
In Example 2 below, similarly, the outlet CO concentration (ppm) was measured to evaluate the CO removal performance of the catalyst.

Examples 1-1 to 1-5 using the catalysts 1 to 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder and the comparative catalyst 1 including only the noble metal-based catalyst powder are used. Table 3 below shows the outlet CO concentration (ppm) of Comparative Example 1-1 and Comparative Example 1-2 using Comparative Catalyst 2 made of only the copper-based catalyst powder.
Further, Examples 1-1 to 1-5 using the catalysts 1 to 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder, and the comparative catalyst 1 including only the noble metal-based catalyst powder. FIG. 7 shows the relationship between the catalyst layer temperature and the outlet CO concentration in Comparative Example 1-1 using NO and Comparative Example 1-2 using Comparative Catalyst 2 made of only the copper-based catalyst powder.

  From Table 3, Examples 1-1 to 1-5 using Catalyst 1 to Catalyst 5 prepared by mixing the copper-based catalyst powder and the noble metal-based catalyst powder have a reaction temperature in the range of 150 to 230 ° C. And the outlet CO concentration (ppm) was almost 150 ppm or less, and it was confirmed that carbon monoxide (CO) could be removed stably.

  On the other hand, in Comparative Example 1-1 using the comparative catalyst 1 composed only of the noble metal catalyst powder, the outlet CO concentration (ppm) is stable at 150 (ppm) or less until the reaction temperature is in the range of about 150 to 200 ° C. However, when the reaction temperature reached 230 ° C., the outlet CO concentration (ppm) rapidly increased to 360 (ppm), and it was confirmed that carbon monoxide (CO) could not be removed stably at high temperatures.

  Moreover, in Comparative Example 1-2 using the comparative catalyst 2 consisting only of the copper-based catalyst powder, the outlet CO concentration (ppm) is 150 (ppm) or more, which is a very high value when the reaction temperature is in the range of 150 to 230 ° C. Thus, it was confirmed that carbon monoxide (CO) could not be removed stably.

  Therefore, by using a catalyst prepared by mechanically mixing the copper-based catalyst powder and the noble metal-based catalyst powder, the catalyst layer stably exhibits high activity in a wide temperature range, and the outlet CO concentration (ppm) It was confirmed that it can be made very low.

The method for preparing the two types of copper-based catalyst powders used in this example is the same as that of the copper-based catalyst powder, and thus the description thereof is omitted.
Of the two types of copper catalyst powders, one catalyst powder was a copper catalyst powder A and the other catalyst powder was a copper catalyst powder B.

The catalyst 6 prepared by mixing the two kinds of copper catalyst powders was prepared by mixing a copper catalyst powder A of selenium oxide (23 mol% Cu / CeO ₂ ) supporting 23 mol% of copper and a γ− catalyst supporting 23 mol% of copper. A catalyst obtained by mixing copper catalyst powder B of alumina (23 mol% Cu / γ-Al ₂ O ₃ ).
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 50%.

The catalyst 7 prepared by mixing the two types of copper catalyst powders was a copper catalyst powder A of γ-alumina (23 mol% Cu / γ-Al ₂ O ₃ ) carrying 23 mol% of copper, and copper. Is a catalyst obtained by mixing a copper-based catalyst powder B of a perovskite complex oxide (LaMn _0.8 Cu _0.2 O ₃ ) supporting bismuth.
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 80%.

The catalyst 8 prepared by mixing the two types of copper catalyst powders is a perovskite-type composite oxide (LaMn _0.8 Cu _0.2 O ₃ ) copper catalyst powder A supporting copper and an oxidation catalyst supporting 23 mol% of copper. It is a catalyst formed by mixing selenium (23 mol% Cu / CeO ₂ ) copper-based catalyst powder B.
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 30%.

The catalyst 9 prepared by mixing the two types of copper catalyst powders was a perovskite-type composite oxide (CuMn ₂ O ₄ ) copper catalyst powder A supporting copper and selenium oxide supporting 23 mol% of copper ( 23 mol% Cu / CeO ₂ ) copper-based catalyst powder B.
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 50%.

The catalyst 10 prepared by mixing the two types of copper-based catalyst powders was a copper-supported perovskite-type composite oxide (LaCuO ₄ ) -supported copper-based catalyst powder A, and γ-alumina (23 mol) supporting 23 mol% of copper. % Cu / γ-Al ₂ O ₃ ) copper-based catalyst powder B.
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 20%.

The comparative catalyst 3 composed only of the copper-based catalyst powder is a catalyst composed only of the copper-based catalyst powder A of γ-alumina (23 mol% Cu / γ-Al ₂ O ₃ ) supporting 23 mol% of copper. The component ratio (% by weight) of the copper-based catalyst powder A at this time was 100%.
The comparative catalyst 4 made of only the copper-based catalyst powder is a catalyst made of only the copper-based catalyst powder B of a perovskite complex oxide (LaMn _0.8 Cu _0.2 O ₃ ) supporting copper.
The component ratio (% by weight) of the copper-based catalyst powder A at this time was 100%.

  The method for mixing the catalyst is the same as in the case of Example 1 described above, and thus the description thereof is omitted.

  As described above, the catalyst compositions of the catalyst 5 to the catalyst 10 prepared by mixing the two types of copper catalyst powders prepared as described above, the comparative catalyst 3 composed of only the copper catalyst powder A, and the catalyst of the comparative catalyst 4 The results of summarizing the component ratio (% by weight) of the copper-based catalyst powder A are shown in Table 4 below.

  Next, as catalyst performances of the catalyst 5 to the catalyst 10 prepared by mixing the two types of copper catalyst powders in this example and the comparative catalyst 3 and the comparative catalyst 4 made of only the copper catalyst powder A, The outlet CO concentration (ppm) was measured under the conditions shown in Table 2 above, and the CO removal performance of the catalyst was evaluated.

  Since the evaluation method of the catalyst performance and the reaction conditions are the same as in the case of Example 1, the description is omitted.

Examples 2-1 to 2-5 using the catalyst 5 to the catalyst 10 prepared by mixing the two types of copper catalyst powders and the comparative catalyst 3 and the comparative catalyst 4 made of only the copper catalyst powder A were used. Table 5 below shows the outlet CO concentrations (ppm) of Comparative Examples 2-1 and 2-2.
Further, Examples 2-1 to 2-5 using the catalysts 5 to 10 prepared by mixing the two kinds of copper-based catalyst powders, and the comparative catalyst 3 and the comparative catalyst composed of only the copper-based catalyst powder A FIG. 8 shows the relationship between the catalyst layer temperature and the outlet CO concentration in Comparative Example 2-1 and Comparative Example 2-2 using 4.

  From Table 5, Examples 2-1 to 2-5 using the catalysts 5 to 10 prepared by mixing the two types of copper-based catalyst powders had an outlet CO concentration within the reaction temperature range of 170 to 230 ° C. (Ppm) was almost 150 ppm or less, and it was confirmed that carbon monoxide (CO) can be removed stably.

  On the other hand, in Comparative Example 2-1 and Comparative Example 2-2 using Comparative Catalyst 3 and Comparative Catalyst 4 made of only the copper-based catalyst powder, the outlet CO concentration (in the range of 150 to 230 ° C.) ppm) was a very high value of 150 ppm or more, and it was confirmed that carbon monoxide (CO) could not be removed stably.

  Therefore, by using a catalyst prepared by mixing the two types of copper-based catalyst powders, the catalyst layer can stably exhibit high activity even at high temperatures, and the outlet CO concentration (ppm) can be very low. It could be confirmed.

  As described above, the CO removal catalyst according to the present invention has a high CO removal performance by using a catalyst obtained by mixing and combining at least one kind of copper catalyst or noble metal catalyst. Therefore, high CO removal performance can be maintained while suppressing the amount of noble metal, and the CO removal reaction can proceed stably, which is suitable for use as a CO removal catalyst in a fuel reformer.

It is a schematic block diagram which shows the state of the CO removal catalyst formed by mixing the copper catalyst and noble metal catalyst which concern on 1st embodiment in a powder state. It is a schematic block diagram which shows the state which the copper-type catalyst and the noble metal are closely_contact | adhered. It is a relationship figure which shows the relationship between the temperature of CO removal catalyst which concerns on 1st embodiment, and CO concentration. It is a relationship figure which shows the relationship between the temperature and CO density | concentration of the CO removal catalyst which concerns on 2nd embodiment. It is the schematic which shows the structure of the fuel reformer which concerns on 3rd embodiment. It is a conceptual diagram which shows a PEFC type fuel cell system. It is a figure showing the relationship between the catalyst layer temperature and exit CO density | concentration of Examples 1-1 to 1-5, Comparative Example 1-1, and Comparative Example 1-2. It is the figure showing the relationship between the catalyst layer temperature and exit CO density | concentration of Examples 2-1 to 2-5, Comparative Example 2-1, and Comparative Example 2-2. It is a relationship figure which shows the relationship between the temperature and CO density | concentration of the catalyst which divided and arrange | positioned the noble metal catalyst conventionally used, the copper catalyst, and the copper catalyst and the noble metal catalyst.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 CO removal catalyst 11 Copper catalyst 12 Oxide 13 Precious metal 14 Precious metal catalyst 20 Fuel reformer 21 Raw fuel 22 Reformed gas 23 Fuel reformer catalyst device 24 CO shift device 25 Fuel gas 26 CO remover

Claims (11)

A CO removal catalyst for selectively oxidizing and removing carbon monoxide in a gas,
A CO removal catalyst comprising: at least one kind of copper-based catalyst or noble metal-based catalyst mixed in a powder state and combined. In claim 1,
A CO removal catalyst, wherein a weight ratio of the precious metal of the precious metal catalyst is 0.05% or less of the total weight of the catalyst. In claim 1 or 2,
The copper catalyst is
An active ingredient comprising metallic copper or copper oxide;
The active ingredient is supported and is at least one of aluminum oxide, cerium oxide, zirconium oxide, zinc oxide, lead oxide, manganese oxide, nickel oxide, titanium oxide, iron oxide, vanadium oxide, cobalt oxide, chromium oxide, and metal silicate. A CO removal catalyst comprising a carrier comprising the above oxide. In any one of Claims 1 thru | or 3,
A CO removal catalyst, wherein the copper-based catalyst is a perovskite complex oxide containing copper or the copper oxide as an active component.   5. The CO removal catalyst according to claim 1, wherein the CO removal catalyst has DSS durability. A fuel reforming catalyst device for reforming hydrocarbon-based raw fuel for fuel cells into reformed gas;
A CO conversion device for converting carbon monoxide generated in the fuel reforming catalyst device;
A fuel reformer comprising: a CO removal device that removes residual carbon monoxide with the CO removal catalyst according to any one of claims 1 to 5 to obtain fuel gas.   7. A fuel cell system comprising: the fuel reformer according to claim 6; and a fuel cell that generates electric power using a gas converted from carbon monoxide.   When removing carbon monoxide remaining in the reformed gas obtained by reforming hydrocarbon-based raw fuel for fuel cells, at least one copper-based catalyst or noble metal-based catalyst is mixed as a CO removal catalyst A CO removal method characterized in that carbon monoxide remaining in the reformed gas is removed using the catalyst formed. In claim 8,
A method for removing CO, wherein a weight ratio of the precious metal of the precious metal catalyst is 0.05% or less of the weight of the total catalyst. In claim 8 or 9,
The copper catalyst is
An active ingredient comprising metallic copper or copper oxide;
The active ingredient is supported and is at least one of aluminum oxide, cerium oxide, zirconium oxide, zinc oxide, lead oxide, manganese oxide, nickel oxide, titanium oxide, iron oxide, vanadium oxide, cobalt oxide, chromium oxide, and metal silicate. A CO removal method comprising a carrier comprising the above oxide. In any one of claims 8 to 10,
The method for removing CO, wherein the copper-based catalyst is a perovskite complex oxide containing the copper or the copper oxide as an active component.

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