JP2000126593A - Catalyst for reducing carbon monoxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for reducing carbon monoxide which can efficiently reduce carbon monoxide contained in reformed gas without deactivating the catalyst even when the temperature of a catalyst body is low during start-up and others and does not cause energy loss. SOLUTION: A carrier 42 comprising a substance of high conductivity is coated with a coat layer 44 in which water absorbing parts 44a comprising a water absorbing substance and water repelling parts 44b comprising a water repelling substance are arranged alternately in the gas flow direction. A noble metal catalyst 46 for oxidizing/removing carbon monoxide in reformed gas selectively is supported on the water repelling parts 44b or on the water repelling parts 44b and the water absorbing parts 44a to prepare a catalyst body 40 for reducing carbon monoxide. Water vapor in the reformed gas is condensed in the water absorbing parts 44a, and the water repelling parts 44b carrying the catalyst 46 are heated by the heat of condensation and heat of adsorption of the water vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for reducing carbon monoxide, and more particularly to a catalyst used for a fuel cell using a reformed gas as a hydrogen source, wherein oxygen is added to the reformed gas supplied to the fuel cell. The present invention relates to a carbon monoxide reduction catalyst for injecting and selectively oxidizing and removing a small amount of carbon monoxide contained in a reformed gas.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell uses a polymer electrolyte membrane (hereinafter simply referred to as "electrolyte membrane") as an electrolyte.
Fuel cells that use high power density, have a simple structure, have a relatively low operating temperature, and are quiet. Or it is used as a military power supply. In addition, fuel cells, which use hydrogen as fuel, do not emit nitrogen oxides and carbon dioxide gas in essence, and have recently attracted attention as low-pollution power sources for automobiles. is there.

FIG. 13 shows an example of a fuel cell system using a polymer electrolyte fuel cell using methanol reformed gas as fuel. In FIG. 13A, the fuel cell system 1
Numeral 0 includes a polymer electrolyte fuel cell 20 and a fuel reformer 30.

[0004] The polymer electrolyte fuel cell 20 comprises an electrolyte membrane 2
The basic structure is a structure in which the fuel electrode 24 and the air electrode 26 are joined to both surfaces of the two. An electromotive force is obtained by supplying a reformed gas containing hydrogen as a main component obtained in the fuel reformer 30 to the fuel electrode 24 and supplying a gas containing oxygen such as air to the air electrode 26 side. The generated electromotive force is supplied to a load 28 connected to the fuel electrode 24 and the air electrode 26.

[0005] The fuel reformer 30 includes a reforming section 32, a methanol vapor generator 34, a steam generator 36, and a carbon monoxide reduction device 38. The reforming section 32 is a section that reacts methanol vapor and steam generated by the methanol vapor generator 34 and the steam generator 36 in the presence of a catalyst to generate a reformed gas containing hydrogen as a main component.

[0006] The carbon monoxide reducing device 38 removes a small amount of carbon monoxide contained in the reformed gas obtained in the reforming section 32 and converts the reformed gas from which carbon monoxide has been removed into the fuel electrode 2.
4 is a part to be supplied.

[0007] The reformed gas obtained by steam reforming of methanol is characterized by having a lower carbon monoxide concentration than the reformed gas obtained by steam reforming of naphtha or the like. However, it is known that the platinum-based catalyst used as the electrode catalyst of the fuel electrode 24 is poisoned even with a small amount of carbon monoxide, and significantly lowers the cell performance in a high current density region. .

In particular, since the operating temperature of the polymer electrolyte fuel cell 20 is as low as 50 to 100 ° C., it is necessary to reduce the concentration of carbon monoxide in the fuel gas supplied to the anode 24 to several tens ppm. The reformed gas obtained by steam reforming of methanol cannot be supplied to the fuel electrode 24 as it is.

Therefore, in the fuel cell system 10 using the polymer electrolyte fuel cell 20, the fuel reformer 30
It is indispensable to provide a carbon monoxide reducing device 38 to reduce or separate a small amount of carbon monoxide contained in the reformed gas.

There are various devices for reducing or separating carbon monoxide in the reformed gas. One of them is a catalyst in which a small amount of air is injected into the reformed gas and a noble metal catalyst is supported. There is known an apparatus for selectively oxidizing and removing carbon monoxide in a reformed gas using a medium. FIG. 13B is a schematic configuration diagram of a carbon monoxide reduction device 38 of this type.

Referring to FIG. 13B, the carbon monoxide reducing device 38 includes an oxidizing section 38a and oxygen injection means 38b. The reformed gas generated in the reforming section 32 is supplied through the oxygen injection means 38b. Then, a gas containing oxygen such as air is injected, and carbon monoxide in the reformed gas is selectively oxidized and removed by a catalyst 40 provided in the oxidizing section 38a.

The catalyst body 40 used in the carbon monoxide reducing device 38 is formed by forming a coating layer made of porous γ-alumina or the like on a carrier made of metal or cordierite, and forming a noble metal such as platinum or ruthenium on the coating layer. What carries a catalyst is common. According to the carbon monoxide reducing device 38 provided with this type of catalyst body 40, the concentration of carbon monoxide in the reformed gas can be reduced to about several tens of ppm, and the deterioration of battery characteristics is dramatically improved. (For example, Japanese Patent Application Laid-Open No. 3-208801).

[0013]

However, in the catalyst body used in this type of carbon monoxide reduction apparatus, the activity of a noble metal catalyst such as platinum or ruthenium supported on a porous γ-alumina coat layer is considered. The temperature is 60 ~
200 ° C. The reformed gas obtained by steam reforming of methanol usually contains 5 to 30% of steam.

Therefore, when the temperature of the catalyst body is low, for example, at the time of starting, there is a problem that water vapor is condensed in the coat layer, and the catalyst carried on the coat layer is wetted and deactivated.
When the catalyst is deactivated, the reformed gas containing carbon monoxide passes through the carbon monoxide reduction device and reaches the fuel electrode, and the electrode catalyst of the fuel electrode is poisoned by carbon monoxide, causing a decrease in battery performance. Become.

In order to solve this problem, it is common practice to heat the catalyst using means such as electric heating or burner heating before starting to prevent condensation of water vapor on the coating layer. However, there is a problem that extra energy is required for heating the catalyst body, and energy loss is inevitable.

The problem to be solved by the present invention is to efficiently remove carbon monoxide contained in the reformed gas without deactivating the catalyst even when the temperature of the catalyst body is low, for example, during startup. An object of the present invention is to provide a catalyst for reducing carbon monoxide which can be removed by oxidation and does not cause energy loss.

[0017]

Means for Solving the Problems In order to solve the above-mentioned problems, a catalyst for reducing carbon monoxide according to the present invention comprises: a carrier made of a highly heat-conductive substance;
A coat layer having a water-repellent portion made of a water-repellent substance, wherein at least the water-repellent portion carries a noble metal catalyst for selectively oxidizing and removing carbon monoxide in the reformed gas. It is the gist.

The catalyst body for reducing carbon monoxide according to the present invention having the above-described structure, when the reformed gas containing steam is introduced at a time when the temperature of the catalyst body is low, for example, at the time of starting, the steam in the reformed gas is reduced. Part of the water is condensed in a water absorbing part constituting a part of the coat layer provided on the carrier. When the water vapor condenses in the water absorbing portion, the partial pressure of the water vapor inside the catalyst body decreases, and the dew condensation in the water repellent portion which also forms a part of the coat layer is suppressed.

When water vapor is condensed in the water absorbing portion, heat of condensation and heat of adsorption are generated, and the generated heat is transmitted to the water repellent portion carrying the noble metal catalyst directly or through a carrier made of a highly heat conductive material. The water repellent part is heated.

As a result, even when the temperature of the carbon monoxide reducing catalyst is low, such as during startup, the water-repellent portion supporting the noble metal catalyst is less likely to be wet by the condensed water vapor, and the noble metal catalyst is deactivated. Is suppressed. In addition, since the water-repellent portion is heated by the heat of condensation and heat of adsorption when water vapor condenses in the water-absorbing portion, a separate means for heating the carbon monoxide reducing catalyst is not required, and energy loss is avoided. Is done.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 show schematic configuration diagrams of a carbon monoxide reduction catalyst (hereinafter simply referred to as “catalyst”) according to an embodiment of the present invention. 1 to 3, the catalyst body 40 includes a carrier 42, a coat layer 44, and a noble metal catalyst 46.

The carrier 42 serves as a base material of the catalyst body 40. In the example shown in FIG. 1, the carrier 42 having a honeycomb shape is used. The carrier 42 is obtained by extrusion molding, and has a large number of honeycomb channels 42a having a square cross section in the gas flow direction of the reformed gas.
Is attached. As shown in the enlarged sectional view of FIG. 2, a coating layer 44 is provided on the inner wall surface of the honeycomb channel 42a.

FIG. 3 is a sectional view taken along the line AA 'of the catalyst body 40 shown in FIG. In FIG. 3, a coat layer 44 formed on the front and back surfaces of a carrier 42 includes a water absorbing portion 44a and a water repellent portion 44b.
a and the water repellent portions 44b are provided alternately. The water absorbing portion 44a and the water repellent portion 44b are provided symmetrically with respect to the carrier 42.

As shown in FIG. 3, a coating layer 44 in which water absorbing portions 44a and water repelling portions 44b are regularly arranged on a carrier 42.
Is provided, there is an advantage that the calculation of the amount of water vapor that can be held in the water absorbing portion 44a is facilitated.

Note that the carrier 42 is not limited to a honeycomb-shaped carrier obtained by extrusion, and a carrier having another shape may be used. For example, as shown in an enlarged sectional view of FIG. 4, a flat plate 42b and a corrugated plate 42c are sequentially laminated to form a carrier 42, and the inner wall surface of a triangular honeycomb channel 42a provided in the gas flow direction has a water absorbing portion and a water repellent portion. A coat layer 44 in which water portions are provided alternately may be formed. Although not shown, the flat plate 42b and the corrugated plate 42c shown in FIG. 4 may be overlapped and wound up to form the cylindrical carrier 42.

Here, the carrier 42 supports the coat layer 44 composed of the water absorbing part 44a and the water repellent part 44b,
This is for transferring the heat generated in the water absorbing section 44a to the water repelling section 44b. Therefore, the carrier 42 needs to be formed using a substance having high thermal conductivity. Specifically, a preferable example is a metal such as aluminum or stainless steel, or a porous sintered metal.

The water absorbing section 44a is a section for adsorbing water vapor in the reformed gas flowing into the catalyst body 40, and uses a water absorbing substance. Specifically, silica gel, porous carbon,
Preferable examples include γ-alumina, clay minerals, porous polymers, water-absorbing natural fibers, and porous metal bodies made of sintered metal.

The water-repellent portion 44b is a portion serving as an oxidation reaction portion for causing an oxidation reaction of carbon monoxide. Even if water vapor contained in the reformed gas is condensed, the surface is not wetted. And a water-repellent substance. Specifically, a fluororesin such as porous tetrafluoroethylene, a surfactant such as polyoxyethylene octylphenyl ether,
Suitable examples include a hydrophobic silane coupling material such as isobutyltrimethyloxysilane, and a polymer in which a perfluoro group is added to an acrylic molecule.

The noble metal catalyst 46 is for selectively oxidizing and removing a small amount of carbon monoxide contained in the reformed gas, and is supported on the water repellent portion 44b. As the noble metal catalyst 46, fine particles made of platinum, ruthenium, or an alloy thereof are used. The noble metal catalyst 46 is
It suffices if it is carried on at least the water repellent portion 44b, but it may be carried on both the water repellent portion 44b and the water absorbing portion 44a.

Next, another embodiment of the catalyst body 40 according to the present invention will be described. The catalyst body 40 according to the second embodiment shown in FIG. 5 has a water absorbing portion 44a and a water repellent on the front and back surfaces of the carrier 42 in the gas flow direction of the reformed gas, similarly to the catalyst body 40 shown in FIG. Although the coat layer 44 in which the water portions 46b are provided alternately is formed, the difference is that the water absorption portion 44a and the water repellent portion 44b are provided vertically asymmetrically with respect to the carrier 42. Other points are the same as those of the catalyst body 40 shown in FIG.

A catalyst body 40 according to the third embodiment shown in FIG. 6 uses a porous body made of a sintered metal or the like as a carrier 42, and has a water absorbing portion 44a on the inner wall surface of the open pore of the carrier 42. At the same time, a water-repellent portion 44b was provided on a water-absorbing portion 44a formed on the surface of the carrier 42 and on the inner wall surface of the open pores of the carrier 42 to form a coat layer 44, and a noble metal catalyst 46 was carried on the entire surface of the water-repellent portion 44b. Things.

The catalyst body 40 according to the fourth embodiment shown in FIG. 7 uses a porous body made of a sintered metal or the like as the carrier 42, and has a water absorbing portion on the surface of the carrier 42 and the inner surface of the open pores. The coating layer 44 is formed by randomly forming the coating layers 44a and the water-repellent portions 44b, and the noble metal catalyst 46 is supported on both the water-absorbing portions 44a and the water-repellent portions 44b.

Further, in the catalyst body 40 according to the fifth embodiment shown in FIG. 8, a water absorbing portion 44a is formed on the front and back surfaces of the carrier 42, and fine water repellent portions 44b are formed on the surface of the water absorbing portion 44a. The coating layer 44 is scattered, and the catalyst metal 46 is carried on the surface of the fine water-repellent portion 44b.

Next, the operation of the catalyst according to the present invention will be described. As shown in FIG. 13B, a catalyst body 40 according to the present invention is incorporated in an oxidizing section 38a of a carbon monoxide reduction device 38 provided between the fuel cell 20 and the reforming section 32.

Next, while the catalyst body 40 is at room temperature or lower, methanol vapor and steam are supplied to the reforming section 32,
Generate reformed gas. In the obtained reformed gas, hydrogen,
Since a small amount of carbon monoxide is contained in addition to carbon dioxide and water vapor of 5 to 30%, air is injected into the reformed gas by using the oxygen injection means 38b, and the molar ratio of O ₂ / CO is increased. After the ratio is about 2, it is sent to the oxidizing section 38a.

At the time of starting, since the temperature of the catalyst body 40 is low, when the reformed gas containing steam is introduced, a part of the steam in the reformed gas is converted into the coat layer 44 provided on the carrier 42. Is condensed in the water absorbing portion 44a which constitutes a part of. When a part of the water vapor condenses, the partial pressure of the water vapor inside the catalyst body 40 is reduced, so that the dew condensation in the water repellent portion 44b is suppressed.

When water vapor is condensed in the water absorbing portion 44a, heat of condensation and heat of adsorption are generated, and the water repelling portion 44b carrying the noble metal catalyst 46 directly from the water absorbing portion 44a or through the carrier 42 made of a high heat conductive material. Informed, water-repellent part 44
b is heated.

Therefore, even when the temperature of the catalyst body 40 is low, such as at the time of starting, the water-repellent portion 44b carrying the noble metal catalyst 46 is hardly wet by the condensed water vapor, and the deactivation of the noble metal catalyst 46 is suppressed. Is done. The water-repellent portion 44b is formed by heat of condensation and heat of adsorption when water vapor condenses in the water-absorbing portion 44a.
Is heated, so that a separate means for heating the catalyst body 40 is not required, and energy loss is avoided.

Next, a first method for producing the catalyst body 40 according to the present invention will be described. First, as shown in FIG. 9A, nozzles 50a having a predetermined length provided in the slurry injector 50 are inserted into the honeycomb channels 42a from both ends of the honeycomb-shaped carrier 42. In this case, the number of the nozzles 50a is the same as the number of the honeycomb channels 42a provided in the carrier 42, and the length of the nozzle 50a is
The length may be the same as the length of the water absorbing portion 44a to be formed.

Next, as shown in FIG. 9B, when the setting of the nozzle 50a is completed, the slurry injector 5
Using 0, a predetermined amount of slurry 52 containing a water-repellent material is injected into the honeycomb channel 42a. Further, FIG.
As shown in (c), the carrier 42 is rotated with the slurry injector 50 inserted into the carrier 42, and the injected slurry 52 is uniformly coated on the inner wall surface of the honeycomb channel 42a.

After the coating of the slurry 52 is completed, the slurry injector 50 is withdrawn from the carrier 42 and
Dry at around 0 ° C. to remove moisture from the coating,
Next, when the coating is fired at 300 to 600 ° C., the coating becomes porous and the water-repellent portion 44b is formed. FIG. 9D shows this state.

Further, the water-repellent portion 44b is impregnated with a substance containing a noble metal catalyst such as platinum or ruthenium, dried and fired. If formed, three layers of the water absorbing portion 44a, the water repellent portion 44b carrying the noble metal catalyst 46, and the water absorbing portion 44a are alternately formed on the inner wall surface of the honeycomb channel 42a along the gas flow direction of the reformed gas. The obtained catalyst body 40 is obtained. FIG. 9 shows this state.
(E).

In the above manufacturing method, the water-repellent portion 4
Although the noble metal catalyst 46 is supported on only 4b, after forming the water repellent portion 44b and the water absorbing portion 44a, the water repellent portion 44b and the water absorbing portion 44a may be impregnated with a substance containing the noble metal catalyst. Thereby, the catalyst body 40 in which the noble metal catalyst 46 is supported on both the water absorbing portion 44a and the water repellent portion 44b can be obtained.

Next, a second method for producing the catalyst body 40 according to the present invention will be described. The carrier 42 shown in FIG. 10 is obtained by laminating a flat plate 42b and a waste plate 42c. As shown in FIGS. 10 (a) and 10 (b), a slurry containing a water-absorbing substance and a slurry containing a water-repellent substance are previously applied to the flat plate 42b and the waste plate 42c, respectively. The water-repellent portions 44b are formed alternately.

The flat plate 42b and the waste plate 42c are
As shown in (c), they are alternately overlapped and fixed using a holder (not shown). Next, the applied water absorbing portion 4
4a and the water-repellent portion 44b are dried and fired,
After impregnating the catalyst material into the entire 4a and the water-repellent portion 44b,
When this is fired, the catalyst body 40 in which the water absorbing portions 44a and the water repellent portions 44b are alternately formed is obtained.

Since the carrier 42 only needs to have a large thermal conductivity in the gas flow direction, the flat plate 42b and the waste plate 42c may be simply superposed as described above, but the flat plate 42b and the waste plate 42c are firmly connected. If you want
After removing the slurry applied to the contact portion between the flat plate 42b and the waste plate 42c, it may be joined by means such as spot welding. Further, the noble metal catalyst 46 may be supported only on the water repellent portion 44b.

Next, a third method for producing the catalyst body 40 according to the present invention will be described. The carrier 42 shown in FIG.
Is made of a porous sintered metal plate, and has a large number of open pores 42 d inside the carrier 42. This carrier 42
When a slurry containing a water-absorbing substance is applied to both surfaces of the substrate and dried, a water-absorbing portion 44a is formed on the surface of the carrier 42 and the inner surface of the open pores 42d. FIG. 11 shows this state.
(B).

After the water absorbing portion 44a has been formed, both sides of the carrier 42 are scraped off, as shown in FIG.
Carrier 42 having water absorbing portion 44a formed only on inner wall surface of 2d
Is obtained. Further, the surface of the carrier 42 and the open pores 4
A slurry containing a water-repellent substance and a catalyst substance is coated on the water-absorbing section 44a formed on the inner surface of 2d to form a water-repellent section 44b. FIG. 11D shows this state. Then, the obtained carrier 42 is laminated, dried and fired to obtain the catalyst body 40 having the water absorbing portion 44a and the water repellent portion 44b formed on the surface and the open pores 42d.

A slurry containing a water-absorbing substance, a water-repellent substance and a catalyst substance is applied to both sides of the carrier 42 made of a porous metal plate shown in FIG.
As shown in FIG. 5, the water absorbing portions 44a and the water repelling portions 44b are formed randomly on the surface of the carrier 42 and the inner wall surface of the open pores 42d, and the noble metal catalyst 46 has the water absorbing portions 44a and the water repelling portions 4b.
4b is obtained.

Next, a fourth method for producing the catalyst body 40 according to the present invention will be described. First, a slurry containing a water-absorbing substance is poured into a honeycomb channel 42a of a honeycomb-shaped carrier 42 as shown in FIG. 12A, and a water-absorbing portion 44a is formed on the entire inner wall surface of the honeycomb channel 42a.

Next, after the water absorbing portion 44 a is dried, the slurry containing the water repellent material and the catalyst material is sprayed from the opening end of the carrier 42 to the honeycomb channel 42 a using the injection nozzle 52.
When the slurry is sprayed toward the inside, the slurry formed into droplets having a diameter of about 10 to 20 μm or less by the spray nozzle 52 adheres to the water absorbing portion 44a. Then, when this is dried and fired, the noble metal catalyst 4
Thus, the catalyst body 40 in which the granular water-repellent portions 44b carrying 6 are formed intensively is obtained. FIG. 12 shows this state.
(B).

The granular water-repellent portion 44b can be formed by the following method in addition to the method using the spray nozzle 52. That is, as shown in FIG. 12A, after forming a water absorbing portion 44a on the inner wall surface of the honeycomb channel 42a, a water repellent substance and a catalyst substance are suspended and dissolved in a chargeable liquid such as a methanol aqueous solution. Is suspended in the honeycomb channel 42a as negatively charged liquid fine particles of 10 μm or less. Next, if the carrier 42 is positively charged, the liquid fine particles can be uniformly dispersed and attached to the inner wall surface of the honeycomb channel 42a.

The catalyst body 40 manufactured by using the method shown in FIG. 9 is incorporated in the oxidizing section 38a of the carbon monoxide reduction device 38 shown in FIG. 13B, and a power generation test of the polymer electrolyte fuel cell 20 is performed. Was. As a result, according to the catalyst body 40 according to the present invention, the carbon monoxide concentration at the time of startup is reduced as compared with a conventional catalyst body in which a noble metal catalyst is supported on a coat layer made of gamma alumina or the like, and Polymer fuel cell 20
It was confirmed that the power generation performance was improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. It is.

For example, in the above embodiment, the water absorbing portion 44
a and the water-repellent portions 44b are alternately arranged along the gas flow direction of the reformed gas, but the water-absorbing portions 44a and the water-repellent portions 44b are alternately arranged along the direction perpendicular to the gas flow of the reformed gas. You may.

In the above embodiment, the water absorbing portion 44a
The water-repellent portion 44b is heated by the heat of condensation and heat of adsorption when steam is condensed by steam. Electric heating for directly energizing and heating the carrier, or burner heating for heating the carrier from the outside with a burner, etc. Alternatively, the water-repellent portion 44b may be heated using another means for heating the carrier. As a result, both the reduction of the energy loss required for the electric heating and the burner heating and the reliable reduction of carbon monoxide at the time of starting or the like can be achieved at the same time.

Further, the catalyst for reducing carbon monoxide according to the present invention is not limited to reducing carbon monoxide in the reformed gas supplied to the polymer electrolyte fuel cell, but may be used for the polymer electrolyte fuel cell. It can also be used for reducing carbon monoxide in the reformed gas supplied to the phosphoric acid fuel cell whose operating temperature is higher than that of the battery, whereby the same effect as in the above embodiment can be obtained.

[0058]

The carbon monoxide reducing catalyst according to the present invention has a water absorbing portion made of a water absorbing material and a water repelling portion made of a water repellent material on a carrier made of a highly heat conductive material. Since the noble metal catalyst that covers the coat layer and selectively oxidizes and removes carbon monoxide in the reformed gas is supported on at least the water-repellent portion, such as when starting, when the temperature of the catalyst body is low, Even so, there is an effect that the condensed water vapor is selectively absorbed by the water absorbing portion, and the deactivation of the noble metal catalyst supported on the water repellent portion is suppressed.

The carbon monoxide reducing catalyst according to the present invention has a water absorbing portion formed on a carrier made of a material having a high thermal conductivity, and uses the heat of condensation and heat of adsorption of water vapor condensed in the water absorbing portion to provide water repellency. Since the section is heated, there is an effect that a separate heating means for preventing deactivation of the noble metal catalyst such as electric heating and burner heating becomes unnecessary.

Therefore, if this is applied to, for example, a fuel cell system using a polymer electrolyte fuel cell, a large energy loss occurs even when the temperature of the carbon monoxide reduction catalyst is low, such as during startup. Without accompanying, it is possible to efficiently oxidize and remove carbon monoxide, thereby making it possible to dramatically improve the power generation efficiency of the fuel cell system. .

[Brief description of the drawings]

FIG. 1 is an external perspective view of a carbon monoxide reduction catalyst according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the carbon monoxide reduction catalyst body shown in FIG. 1 as viewed from a gas flow direction.

FIG. 3 AA ′ of the catalyst for reducing carbon monoxide shown in FIG.
It is a line sectional view.

FIG. 4 is an enlarged cross-sectional view of a carbon monoxide reduction catalyst having a triangular cross-sectional shape of a honeycomb channel as viewed from a gas flow direction.

FIG. 5 is an enlarged sectional view of a catalyst body for reducing carbon monoxide according to a second embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of a carbon monoxide reduction catalyst according to a third embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a carbon monoxide reduction catalyst according to a fourth embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a carbon monoxide reduction catalyst according to a fifth embodiment of the present invention.

FIG. 9 is a diagram illustrating a first method for producing a catalyst for reducing carbon monoxide according to the present invention.

FIG. 10 shows a second example of the carbon monoxide reduction catalyst according to the present invention.
FIG. 4 is a view for explaining a manufacturing method of the present invention.

FIG. 11 shows a third example of the catalyst for reducing carbon monoxide according to the present invention.
FIG. 4 is a view for explaining a manufacturing method of the present invention.

FIG. 12 shows a fourth example of the carbon monoxide reduction catalyst according to the present invention.
FIG. 4 is a view for explaining a manufacturing method of the present invention.

13 (a) is a schematic configuration diagram showing an example of a fuel cell system using a polymer electrolyte fuel cell using methanol reformed gas as a fuel, and FIG. 13 (b) is a schematic configuration diagram of FIG.
FIG. 3 is a schematic configuration diagram illustrating an example of a carbon monoxide reduction device used in the fuel cell system illustrated in FIG.

[Explanation of symbols]

 Reference Signs List 40 Catalyst for reducing carbon monoxide 42 Carrier 44 Coating layer 44a Water absorbing part 44b Water repellent part 46 Noble metal catalyst

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsushi Ogino 1-term Toyota-cho, Toyota-shi, Aichi F-term in Toyota Motor Corporation (reference) 4G040 EA02 EA05 EB01 EC01 EC03 4G069 AA03 BA17 BA41A BC70B BC75B CC17 CC32 DA05 EA18 EA20 EB01 FA02 5H027 AA06 BA01 BA16

Claims (1)

[Claims] 1. A coating layer comprising a water-absorbing part made of a water-absorbing substance and a water-repelling part made of a water-repellent substance is coated on a carrier made of a highly heat-conductive substance. And a noble metal catalyst for selectively oxidizing and removing carbon monoxide in the reformed gas.