JP2003275587A - Carbon monoxide selective oxidation catalyst and hydrogen purification apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogen purification apparatus capable of removing CO in a reformed gas consisting essentially of hydrogen and containing CO to be used for a fuel cell to low concentration in a wide temperature range. <P>SOLUTION: The hydrogen purification apparatus is provided with a reformed gas supply source for supplying the reformed gas containing hydrogen, an oxidizing gas supply source for incorporating an oxidizing gas containing oxygen into the reformed gas supplied from the reformed gas supply source and a catalyst layer composed of two layers of an upstream catalyst layer and a downstream catalyst layer through which the reformed gas containing oxygen is passed. In two catalyst layers, the downstream catalyst layer into which a high temperature gas flows contains a alloy particle of platinum and ruthenium and a platinum particle and the upstream catalyst layer contains an alloy particle of platinum and ruthenium and a ruthenium particle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hydrogen purifier. More specifically, the present invention relates to an apparatus for removing CO in a reformed gas containing hydrogen monoxide (hereinafter, referred to as CO) as a main component, which is used as fuel for fuel cells and the like.

[0002]

2. Description of the Related Art Conventionally, hydrogen used in a fuel cell or the like is produced by mixing water vapor with a hydrocarbon fuel such as methane, propane, gasoline, kerosene, an alcohol fuel such as methanol or an ether fuel such as dimethyl ether, It is generated by bringing it into contact with a heated reforming catalyst. Usually, hydrocarbon fuel is reformed at a temperature of about 500 to 800 ° C, and alcohol or ether fuel is reformed at a temperature of about 200 to 400 ° C.

CO is generated during the reforming, but the concentration of the generated CO increases as the reforming is performed at a higher temperature. Especially when a hydrocarbon fuel is used, the CO concentration is 10% by volume.
Before and after. Therefore, a CO conversion catalyst is used to react CO with hydrogen to reduce the CO concentration to several thousands ppm to several volume%.

Further, in the case of a fuel cell that operates at a low temperature of 100 ° C. or lower, such as a polymer electrolyte fuel cell used for vehicles or for household use, P used as an electrode.
Since the t catalyst is poisoned by CO contained in the reformed gas, it is necessary to remove the CO concentration to 100 ppm or less, preferably 10 ppm or less before supplying the reformed gas to the fuel cell. Therefore, a CO purifying unit filled with a catalyst is provided in the hydrogen purifying apparatus, and CO is removed by methanating CO or selectively oxidizing a small amount of air to oxidize CO.

[0005]

The Pt catalyst is effective in selectively removing CO by oxidizing it, but the temperature range in which CO can be effectively removed is limited to about 30 ° C. Precise temperature control is required. However, it is difficult to control the temperature because the heat of reaction is large.

When CO is methanated and removed, catalysts such as Pd, Ru, Ni or Rh are effective, but these catalysts promote not only CO but also methanation of carbon dioxide. , The optimum temperature range for effectively removing CO is limited to about 30 ° C.

As described above, the conventional apparatus has a problem that the optimum temperature range of the catalyst capable of effectively removing CO is narrow and precise temperature control is required, and that the control is difficult. In particular, many problems remain for applications such as in-vehicle use and home use where the load fluctuations that repeat start and stop are large. Against this background, it has been attempted to use a catalyst obtained by alloying Pt-Ru with alumina or zeolite as a carrier. Such an alloyed catalyst exhibits excellent properties over a wider temperature range than Pt catalysts, Pd catalysts, and Ru catalysts. However, since the CO selective oxidation reaction is an exothermic reaction, it is difficult to always maintain the catalyst temperature in the active temperature region when the CO treatment amount changes. The present invention has been made in view of the above problems of the hydrogen purification apparatus, and an object of the present invention is to provide a hydrogen purification apparatus that can stably remove CO to a low concentration in a wide temperature range.

[0008]

In order to solve the above problems, the catalyst for selective oxidation of carbon monoxide according to the first aspect of the present invention is characterized by containing alloy particles of platinum and ruthenium and platinum particles.

The catalyst for selective oxidation of carbon monoxide according to the second aspect of the present invention is characterized by containing alloy particles of platinum and ruthenium and ruthenium particles.

The catalyst for selective oxidation of carbon monoxide according to the third aspect of the present invention is such that platinum is supported on a carrier by an impregnation method using a platinum salt aqueous solution, hydrogen reduction is performed, and the catalyst is impregnated using a ruthenium salt aqueous solution. It is characterized in that ruthenium is further supported on the carrier to carry out hydrogen reduction.

Further, the catalyst for selective oxidation of carbon monoxide according to the fourth aspect of the present invention is such that ruthenium is supported on a carrier by an impregnation method using an aqueous solution of ruthenium salt, hydrogen reduction is performed, and the catalyst is impregnated using an aqueous solution of platinum salt. It is characterized in that platinum is further supported on the carrier to carry out hydrogen reduction.

The hydrogen purifying apparatus of the present invention comprises a purifying section having a catalyst layer containing at least one of the carbon monoxide selective oxidation catalysts of the first to fourth aspects of the present invention, and a hydrogen purifying section. And a reforming gas supply unit for supplying a reforming gas containing oxygen and an oxidizing gas supply unit for supplying an oxidizing gas containing oxygen to the carbon monoxide removing device.

Further, in the hydrogen purifier of the present invention, in the hydrogen generator, the catalyst layer includes a plurality of catalyst layers arranged in parallel in the flow direction of the reformed gas, and the temperature of the plurality of layers is high. At least one layer into which the gas flows is the first or the third
It is effective that at least one layer of the plurality of layers into which the low temperature gas flows contains the second or fourth carbon monoxide selective oxidation catalyst of the present invention. is there.

Further, in the hydrogen purifier of the present invention, in the hydrogen generator, an oxidizing gas containing oxygen is further supplied between the catalyst layer arranged on the upstream side and the catalyst layer arranged on the downstream side. It is effective to provide an oxidizing gas supply unit for this purpose.

Further, the method for operating the hydrogen purifying apparatus of the present invention is characterized in that when the hydrogen purifying apparatus is started, a reformed gas whose water content is reduced by condensation is supplied to the purifying section.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the hydrogen purifying apparatus of the present invention, the reformed gas containing hydrogen and CO is supplied from the reformed gas supply unit and the oxygen-containing oxidizing gas supplied from the oxidizing gas supply unit. After being mixed, it passes through the CO purification catalyst layer provided in the purification unit.

The reformed gas containing hydrogen and CO used in the present invention is obtained by mixing hydrocarbon-based, alcohol-based or ether-based fuel with water vapor or air and passing it through a heated reforming catalyst layer for reforming. After that, CO is passed through the CO conversion catalyst layer to react CO with hydrogen, and the CO concentration is increased to several thousand p
It is reduced to about pm to several volume%. The composition of the reformed gas after passing through the CO shift catalyst layer varies depending on the reforming method and the fuel type, and cannot be said to be unconditional, but if steam is excluded, hydrogen is 40 to 80% by volume and carbon dioxide is 8 to 25% by volume. ,
CO is generally 0.1 to 2% by volume. For example, when methane is steam reformed, hydrogen is about 80% by volume,
18-20% by volume of carbon dioxide and thousands of ppm of CO
~ 1% by volume. Further, in the case of alcohol-based or ether-based fuels that can undergo a reforming reaction at low temperatures, the CO concentration after reforming may be around 1% by volume, and in some cases conversion by the CO shift catalyst layer may not be necessary. . It should be noted that such a difference in composition does not cause a substantial difference in the effect obtained by using the hydrogen purifier of the present invention.

The reformed gas supplied from the reformed gas inlet is
It is sent to the reaction chamber in which the CO purification catalyst is installed together with the air supplied by the air pump. Air is supplied from the air pump so that the oxygen concentration is about 1 to 3 times the CO concentration, for example, when the CO concentration is 1% by volume, the oxygen concentration is 1 to 3% by volume. The reformed gas mixed with oxygen is
After the CO is removed by the CO purification catalyst, it is sent to the reformed gas outlet. Further, in order to keep the reactor at a constant temperature, the outer periphery is covered with a heat insulating material made of ceramic wool in a necessary portion.

The hydrogen purification apparatus of the present invention contains a reformed gas supply section for supplying a reformed gas containing hydrogen and carbon monoxide, and oxygen contained in the reformed gas supplied from the reformed gas supply section. It comprises an oxidizing gas supply unit for mixing the oxidizing gas and a purifying unit having a catalyst layer through which the reformed gas mixed with oxygen passes. When the catalyst layer contains, as a main component, metal particles obtained by alloying platinum and ruthenium and platinum particles, a reverse shift in a high temperature range is obtained as compared with the case where only alloyed metal particles are contained. This is effective in that the reaction is suppressed and the CO removal characteristics by the CO selective oxidation reaction in a wider range of 100 ° C. to 160 ° C. including the high temperature flow region are maintained. In addition, when the catalyst layer contains, as main components, metal particles in which platinum and ruthenium are alloyed and ruthenium particles, a temperature of 80 ° C. including a low temperature region is included as compared with the case where only the alloyed metal particles are included. ~ 14
It is effective in that the catalytic activity for the CO selective oxidation reaction can be obtained in a wider temperature range of 0 ° C.

The catalyst layer has at least two layers, an upstream catalyst layer located upstream of the reformed gas flowing through the purification section and a downstream catalyst layer located downstream of the reformed gas. Contains metal particles and ruthenium particles alloyed with platinum and ruthenium, and the downstream catalyst layer contains platinum-ruthenium alloy particles and platinum particles. In this case, if a low-temperature reformed gas of around 80 ° C. to 100 ° C. is supplied to the purifying unit, even if the reformed gas becomes high temperature due to heat generation due to the selective oxidation reaction on the upstream side, if the reformed gas is 160 ° C. or lower, It becomes possible for the catalyst on the side to exhibit sufficient activity. That is, by using the above two-layer catalyst,
It has a catalytic activity in the temperature range of ° C and can effectively remove CO. Thus, on the downstream side where the relatively high temperature reformed gas flows, a catalyst containing metal particles and platinum particles alloyed with platinum and ruthenium is used,
On the upstream side through which the reformed gas at a relatively low temperature flows, it is desirable to use a catalyst containing metal particles in which platinum and ruthenium are alloyed and ruthenium particles. The distribution of the constituent metals in such metal particles can be measured by TEM using XM.
It can be confirmed by performing A analysis.

In the platinum-ruthenium alloy described here, platinum and ruthenium are 40 to 60 atom% each.
Is desirable. In the present invention, the platinum particles and ruthenium particles that coexist with the alloy refer to those in which trace amounts of other metals in the particles are not more than 90 atm% of platinum and ruthenium in an analyzer such as XMA. Refers to each configured.

It is desirable to provide an oxidizing gas supply section for mixing the oxidizing gas containing oxygen between the upstream catalyst layer and the downstream catalyst layer. This allows for lower concentrations,
CO can be reduced.

The catalyst containing platinum and ruthenium-alloyed metal particles and platinum particles supports platinum by an impregnation method from a carrier and a platinum salt aqueous solution, and then hydrogen reduction is carried out, followed by a ruthenium salt aqueous solution. Can be prepared by supporting ruthenium by the impregnation method and then performing hydrogen reduction.

A catalyst containing metal particles ruthenium alloyed with platinum and ruthenium and ruthenium particles are loaded with ruthenium from a carrier and an aqueous solution of ruthenium salt by an impregnation method, and then hydrogen reduction is performed, followed by an impregnation method with an aqueous solution of platinum salt. It is possible to prepare by carrying out platinum reduction after carrying platinum by.

In the hydrogen purifying apparatus of the present invention, when the hydrogen purifying apparatus is started, water in the reformed gas is condensed upstream of the catalyst layer, and then the reformed gas is introduced into the catalyst layer, whereby the catalyst is Since the catalyst does not become submerged in water and the low-temperature activity of the catalyst can be sufficiently exerted, the catalyst can be quickly started.

In a reaction such as an anode electrode catalyst in which a Pt-Ru alloy catalyst is often used, CO adsorbed on platinum and Ru
It is believed that a reaction with water that has been adsorbed and decomposed on water occurs. The alloying of platinum and ruthenium increases the probability that ruthenium will be next to platinum,
It is said that the reaction is easy to proceed.

Platinum has a face-centered cubic structure, but when it is alloyed with a different kind of metal, the lattice constant changes. The change can be easily measured by measuring XRD.

The catalyst is preferably supported on a carrier so that it can be supported in high dispersion. The catalyst carrier is not particularly limited as long as it can support the catalytically active component in a highly dispersed state. Examples of such materials include alumina, silica, silica-alumina, magnesia, titania, zeolite and the like. As the type of zeolite capable of supporting the catalytically active component in a highly dispersed state, A-type zeolite, X
Type zeolite, Y type zeolite, beta type zeolite,
Examples include mordenite and ZSM-5. These carriers may be used alone or in combination of two or more.

Further, as an embodiment, a carrier substrate such as a cordierite honeycomb may be coated or formed into a pellet shape.

[0030]

EXAMPLES The hydrogen purifying apparatus of the present invention will be described below in more detail with reference to Examples.

Example 1 Using a chloroplatinic acid aqueous solution,
Platinum was supported on γ-alumina by the impregnation method, and hydrogen reduction was performed at 350 ° C. Ruthenium is supported on this Pt / alumina by an aqueous solution of ruthenium chloride, and hydrogen reduction treatment is performed at 900 ° C. to obtain Pt-Ru / alumina (catalyst A: Pt-R
u-900H2) was prepared. Note that platinum was 50 atm% and ruthenium was 50 atm%. When the lattice constant was measured by XRD, it was 3.859Å, and the lattice constant of Pt was 3.923Å
It was confirmed to be smaller and alloyed.
This catalyst A had Pt and Ru of about 1: 1.2 by XMA analysis.
Particles with an atomic ratio of, and particles with 90% or more of Pt were observed. This catalyst A was ball-milled by adding alumina sol and water to a solid content of 5 wt% to prepare a catalyst slurry. This catalyst slurry is
A cordierite honeycomb having a length of 10 mm and a length of 10 mm was coated. The honeycomb was loaded so that the loaded amount was Pt 3 g / liter. The obtained catalyst was installed in the purifying section of the model test device of the hydrogen purification device, and CO was 0.5% by volume, carbon dioxide was 15% by volume, water vapor was 15% by volume, and the balance was hydrogen at a dew point of 75 ° C. Reform simulation gas, SV14000h-1
Introduced in. An air supply unit was provided upstream of the catalyst, and air was supplied from there so that the oxygen concentration was 1% by volume of the whole. The catalyst was heated in an electric furnace, the reaction gas temperature was changed, and the composition of the gas discharged from the outlet of the test apparatus was measured by gas chromatography after removing water vapor. A thermocouple in contact with the catalyst was provided upstream of the catalyst, the catalyst temperature was measured, and the catalyst temperature was changed by changing the temperature of the electric furnace to measure the CO concentration. Catalyst upstream temperature and outlet C
The relationship of O concentration is shown in (Table 1).

Further, ruthenium was supported on γ-alumina by an impregnation method using a ruthenium chloride aqueous solution, and 350
Hydrogen reduction was performed at ° C. Platinum was supported on this Ru / alumina by an aqueous solution of chloroplatinic acid, and hydrogen reduction treatment was performed at 900 ° C., and Ru-Pt / alumina (catalyst B: Ru-Pt-900H
2) was prepared. 50 atm% for platinum and 50 for ruthenium
Atm% was set. When the lattice constant was measured by XRD,
It was 3.852Å, and it was confirmed to be alloyed.
When XMA analysis of this catalyst B was performed, particles containing Pt and Ru in an atomic ratio of about 1.2: 1 and particles having 90% or more of Ru were observed.

Further, using an aqueous solution containing ruthenium chloride and chloroplatinic acid, γ-alumina was loaded with platinum and ruthenium by an impregnation method and subjected to hydrogen reduction treatment at 900 ° C.
Pt-Ru / alumina (catalyst C: Pt-Ru-simultaneous 900H2) was prepared. Note that platinum was 50 atm% and ruthenium was 50 atm%. When the lattice constant was measured by XRD, it was 3.850Å
It was confirmed that they were alloyed. When an XMA analysis of this catalyst C was performed, Pt and Ru were contained in an atomic ratio of about 1: 1, and no particles in which a certain metal was localized were found.

Further, using an aqueous solution containing ruthenium chloride and chloroplatinic acid, γ-alumina was loaded with platinum and ruthenium by an impregnation method and baked in air at 500 ° C. to obtain Pt-R.
u / alumina (catalyst D: Pt-Ru-simultaneous 500 Air) was prepared. Note that platinum was 50 atm% and ruthenium was 50 atm%. When XRD was measured, platinum was present as an oxide and no alloying was observed.

Further, platinum was supported on γ-alumina by an impregnation method using a chloroplatinic acid aqueous solution, and hydrogen reduction treatment was performed at 900 ° C. to obtain Pt / alumina (catalyst E: Pt-900H2).
Was prepared. On the other hand, using ruthenium chloride aqueous solution, ruthenium was supported on γ-alumina by an impregnation method, and 900
Hydrogen reduction treatment was carried out at 0 ° C. to prepare ruthenium / alumina (catalyst F: Ru-900H2).

As with catalyst A, catalysts B to F were loaded on a honeycomb, and CO selective oxidation characteristics were examined. The loading amount was Pt 3 g / liter, and the catalyst F was Ru 3 g / liter. The results are shown in (Table 1). As shown in (Table 1), the catalyst A containing platinum / ruthenium alloyed metal particles and platinum particles has excellent characteristics at high temperature as compared with the catalyst C composed of only platinum / ruthenium alloy. Catalyst B containing alloyed metal particles and ruthenium particles
Is superior to the catalyst C consisting of platinum and ruthenium alloy only at low temperature. Further, the non-alloyed catalyst D has a slightly low CO purification characteristic and its active temperature range is not wide. Also, the platinum catalyst E and the ruthenium catalyst F have narrower active temperature regions than the catalysts A and B.

[0037]

[Table 1]

(Example 2) The catalyst B was added with 5 w as a solid content.
Alumina sol and water were added so as to be t%, and the mixture was ball-milled to prepare a catalyst slurry. This catalyst slurry is
A cordierite honeycomb having a diameter of 50 mm and a length of 10 mm was coated. The supported amount should be Pt 3g / liter,
Supported on a honeycomb. The obtained catalyst was placed in a reaction chamber in which the outer periphery of a hydrogen purifier was covered with a ceramic heat insulating material, and C
O 1 volume%, carbon dioxide 15 volume%, steam 15
A reformed gas having a dew point of 75 ° C. and containing hydrogen by the volume% was introduced from the reformed gas inlet at a flow rate of 10 liters per minute. Air was supplied from the air supply unit so that the oxygen concentration was 2% by volume of the whole. The reformed gas was cooled in front of the reformed gas inlet, and the reformed gas temperature was maintained at 110 ° C. The gas leaving the catalyst supporting catalyst B contained 0.2% by volume of CO.
Air was introduced into the downstream catalyst so that the gas oxygen concentration of 150 ° C. to 170 ° C. passing through the catalyst B was 0.4% by volume of the whole. The downstream catalyst is a catalyst similarly prepared using catalyst A. The results are shown in Table 2 as B → A.

Similarly, the catalyst A is used on both the upstream side and the downstream side.
(A → A), catalyst B on both the upstream and downstream sides
Was measured (B → B), the catalyst A was used on the upstream side, and the catalyst B was used on the downstream side (A → B). The air was supplied between the upstream catalyst and the downstream catalyst so that the oxygen concentration was twice the CO concentration. The results (Table 2)
It was shown to.

As shown in (Table 2), the most excellent characteristics were obtained from catalyst B → catalyst A. This is because the gas is introduced at 110 ° C. into the catalyst B (catalyst containing platinum and ruthenium alloyed metal particles and ruthenium particles), which has an effect at a relatively low temperature, and the gas becomes hot due to reaction heat. The reason is that the catalyst A (catalyst containing platinum and metal particles alloyed with ruthenium and platinum particles) having activity at high temperature was used.

In the constitution of catalyst B → A, catalyst B
When the experiment was conducted without supplying air between the catalyst A and
The outlet gas CO concentration was 542 ppm. As described above, in the present invention, the CO concentration could be reduced more effectively by providing the oxidizing gas supply unit for mixing the oxidizing gas containing oxygen between the upstream catalyst layer and the downstream catalyst layer.

[0042]

[Table 2]

(Embodiment 3) The following experiment was conducted assuming the operation at the time of startup. In the configuration of catalyst B → catalyst A in Example 2, first, the reformed gas containing 1% by volume of CO, 15% by volume of carbon dioxide, 15% by volume of steam, and the balance of hydrogen is exhausted through a bypass, and then, Then, the catalyst was switched to room temperature (catalyst B → catalyst A configuration) and the reformed gas maintained at 110 ° C. was supplied. The amount of air supplied to the catalysts B and A was the same as in Example 2. When the outlet CO concentrations were measured 5 minutes and 10 minutes after switching the gas, they were 0.32% by volume and 0.24% by volume, respectively. This is because hot reformed gas is introduced into the catalyst at room temperature,
This is because water was condensed and sufficient catalyst characteristics could not be obtained.

Next, with the same structure, the reformed gas exhausted through the bypass is cooled to 50 ° C., and the catalyst (catalyst B
→ Switched to the configuration of catalyst A). The air supply was the same as above. As a result, the outlet CO concentrations after 5 minutes and 10 minutes were 52 ppm and 47 ppm. This is 50
This is because the water in the reformed gas was condensed when cooled to 0 ° C., and even when it was introduced into the catalyst at room temperature, water was hardly condensed, and sufficient catalytic activity was exhibited.

As described above, at the time of starting the hydrogen purifier, water in the reformed gas is condensed upstream of the catalyst layer, and then the reformed gas is introduced into the catalyst layer to prevent the catalyst from being immersed in water. In addition, since the low temperature activity of the catalyst can be sufficiently exerted, the catalyst could be started promptly.

[0046]

As described above, according to the present invention, by using the metal particles in which platinum and ruthenium are alloyed and the catalyst for selective oxidation of carbon monoxide containing platinum particles, the present invention is more effective than the case where only the alloy particles are used. Also for lower temperature reformed gas,
Stable removal of carbon monoxide.

Further, according to the present invention, by using the alloy particles of platinum and ruthenium and the carbon monoxide selective oxidation catalyst containing the platinum particles, the reformed gas having a higher temperature than that using only the alloy particles can be obtained. Also, carbon monoxide can be stably removed.

Further, according to the present invention, the carbon monoxide selective oxidation catalyst is divided into two layers, that is, an upstream side and a downstream side, and they are used respectively, so that CO can be removed in a wider temperature range.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoshi Taguchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kunihiro Ukai             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 4G069 AA03 AA08 BA01A BA01B                       BA13A BA13B BB02A BB02B                       BC70A BC70B BC75A BC75B                       CB81 CC32 EA19 EB14Y                       EE07 FA02 FB14 FB19 FB43                       FB44                 4G140 EA01 EA02 EA03 EA06 EB35                       EB36                 5H027 AA06 BA01 BA16

Claims (8)

[Claims] 1. A catalyst for selective oxidation of carbon monoxide containing alloy particles of platinum and ruthenium, which are oxygen-containing oxidizing gases, and platinum particles. 2. A catalyst for selective oxidation of carbon monoxide, which comprises alloy particles of platinum and ruthenium and ruthenium particles. 3. By carrying out platinum reduction on a carrier by an impregnation method using an aqueous platinum salt solution and hydrogen reduction, and further carrying ruthenium on the carrier by an impregnation method using an aqueous ruthenium salt solution and performing hydrogen reduction. The resulting carbon monoxide selective oxidation catalyst. 4. A ruthenium is loaded on a carrier by an impregnation method using an aqueous solution of ruthenium salt to carry out hydrogen reduction, and platinum is further loaded on the carrier by an impregnation method using an aqueous solution of platinum salt to carry out hydrogen reduction. The resulting carbon monoxide selective oxidation catalyst. 5. A purifying section having a catalyst layer containing at least one of the carbon monoxide selective oxidation catalysts according to claim 1, and a reformed gas containing hydrogen in the purifying section. A hydrogen purifying apparatus comprising: a reformed gas supply section for supplying oxygen and an oxidizing gas supply section for supplying an oxidizing gas containing oxygen to the carbon monoxide removing apparatus. 6. The catalyst layer comprises a plurality of catalyst layers arranged side by side in the flow direction of the reformed gas, and at least one of the plurality of layers into which a high-temperature gas flows is characterized in that: 5. The carbon monoxide selective oxidation catalyst according to claim 2, wherein at least one of the plurality of layers into which a low temperature gas flows contains the carbon monoxide selective oxidation catalyst according to claim 2. The hydrogen purifier according to claim 5. 7. An oxidizing gas supply unit for supplying an oxidizing gas containing oxygen is provided between the catalyst layer arranged on the upstream side and the catalyst layer arranged on the downstream side. The hydrogen purifier according to claim 6. 8. The method for operating a hydrogen purifier according to claim 6, wherein a reformed gas whose water content is reduced by condensation is supplied to the purification unit when the hydrogen purifier is started.