JPH11114423A - Catalyst for selective oxidation of co in hydrogen gas, its production, and method for removing co in hydrogen gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a CO concentration in hydrogen gas by oxidizing CO selectively by dispersing a complex oxide of a base metal and a rare earth metal including a platinum group metal on the surface of a ceramic-integral type carrier through active alumina. SOLUTION: A catalyst for the selective oxidation of CO in hydrogen gas is prepared by a method in which a complex oxide of a base metal and a rare earth metal including a platinum group metal and active alumina for dispersing the complex oxide finely are applied on the surface of a ceramic-integral carrier and burned. In the complex oxide, palladium and rhuthenium are selected as platinum group metals, copper is selected as a base metal, and cerium and/or neodymium are selected as rare earth metals, and a spinel type is preferable. The complex oxide is obtained by burning a monooxycarbonate synthesized from the hydrothermal reaction of a carbonate. Active alumina used with a complex oxide can be γ-alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for selectively oxidizing CO in hydrogen gas which is suitable for selectively oxidizing CO in a gas containing hydrogen as a main component and containing CO, a method for producing the same, and a method for producing the same. More specifically, for example, in a fuel cell power generator, by selectively oxidizing CO contained in hydrogen gas obtained by reforming methanol or the like supplied to the fuel electrode of the fuel cell, The present invention relates to a catalyst for selectively oxidizing CO in hydrogen gas suitable for reducing CO in hydrogen gas by removing the catalyst, a method for producing the same, and a method for removing CO in hydrogen gas.

[0002]

2. Description of the Related Art A fuel cell power generator in which a fuel electrode and an oxidation electrode are disposed on both sides of an electrolyte and hydrogen and oxygen are supplied to the fuel electrode and the oxidation electrode, respectively, to obtain a cell reaction is low in pollution and energy loss. In recent years, they have attracted attention as automotive batteries because of their advantages, such as being small and advantageous in terms of operability.

[0003] Various types of fuel cells are known depending on the type of fuel or electrolyte, the operating temperature, and the like. Among them, a so-called hydrogen fuel, which uses hydrogen as a fuel and oxygen as an oxidant, is used. Oxygen fuel cells are promising, and low-temperature fuel cells using solid polymers as electrolytes are being developed and put into practical use, and are expected to become more and more popular in the future.

In such a fuel cell, particularly in the case of a low-temperature operation type fuel cell, platinum (platinum catalyst) is used for an electrode.

However, the platinum used for the electrode is
Since it is easily poisoned by CO, if the fuel contains more than a certain level of CO, the power generation performance is reduced and the amount of C
There is a serious problem that power generation may not be possible at all depending on the O concentration. Since the deterioration of the electrode due to CO is particularly remarkable at a lower temperature, it becomes a more important problem in the case of a fuel cell operated at a low temperature.

Accordingly, it is desirable that the fuel of a fuel cell using a platinum-based electrode catalyst be pure hydrogen. However, alcohol fuel such as methanol, which is inexpensive, has excellent storage properties, and is easily set by a public supply system, is desirable. It is common to use a hydrogen-containing gas obtained by steam reforming or the like, and it is considered that a fuel cell power generation system incorporating a reformer will be widely used.

However, since such a reformed gas generally contains a considerable concentration of CO in addition to hydrogen, this CO is converted into CO ₂ which is harmless to the platinum electrode catalyst.
Establishing a technology to reduce the CO concentration in fuel has become an essential condition.

In order to solve the above problem, a shift reaction (water gas shift reaction) described below is used as one of means for reducing the CO concentration in a fuel gas (a hydrogen-containing gas such as a reformed gas). Is also conceivable.

CO + H ₂ O = CO ₂ + H ₂ However, with this reaction alone, there is a limit in reducing the CO concentration due to restrictions on chemical equilibrium, and it is generally difficult to reduce the CO concentration to 1% or less. It is.

Therefore, as a means for reducing the CO concentration to a lower concentration, oxygen or air is introduced into the reformed gas,
A so-called CO selective oxidation catalyst for oxidizing CO to CO ₂ can be considered.

As a CO oxidation catalyst, conventionally, Pt has been used.
/ Alumina, Pt / silica, Pt / carbon, Pd / alumina, etc. are known, but the CO selective oxidation reaction temperature of these catalysts is as low as 100 ° C. or less, and a gas containing a considerable amount of water such as a reforming gas is used. In order to perform the oxidation treatment, the temperature is preferably set to 100 ° C. or higher from the viewpoint of preventing aggregation of water. At the same time, since the CO oxidation reaction is an exothermic reaction, it is difficult to maintain the temperature of the catalyst layer at 100 ° C. or lower. It is.

In the conventional catalyst, at a temperature of 100 ° C. or higher, the selectivity of CO is reduced, and the oxidation reaction of hydrogen proceeds. Therefore, it is impossible to reduce the CO concentration in the reformed gas to about several tens ppm. Will be possible.

On the other hand, Japanese Patent Application Laid-Open No. 9-30802 discloses that
Pt-Ru / Al ₂ O ₃ is a catalyst that selectively promotes the oxidation reaction with CO and is particularly excellent in reaction efficiency.
Catalysts have been proposed.

According to this catalyst, Pt, R on the supported catalyst
u each exhibit properties as a metal, and the following reverse shift reaction occurs on Pt, and the generated CO generates CH ₄ by a methanation reaction on Ru, resulting in CO 2
It is said that the concentration will be reduced.

Reverse shift reaction: CO ₂ + H ₂ → CO + H ₂ O Methanation reaction: CO + 3H ₂ → CH ₄ + H ₂ O

[0016]

However, in order to carry out the above reaction sufficiently, 160 ° C. or higher, preferably 2 ° C.
A temperature of 00 ° C or higher is required, but in the same temperature range, the oxidation reaction of hydrogen is rapidly occurring on Pt metallized with hydrogen, and a large amount of hydrogen is consumed together with the methanation reaction on Ru. Therefore, there is a problem that the CO concentration is relatively increased as a fuel for a fuel cell, which is disadvantageous.

Since the operating temperature of a fuel cell, particularly a low-temperature operating type fuel cell such as a solid polymer electrolyte type fuel cell, is 100 ° C. or lower, the fuel gas temperature is 200 ° C. or higher as described above. In order to efficiently recover heat, a considerably large condenser unit etc. is required,
There has been a problem that the compactness required for automobiles also poses a problem.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is intended to contain hydrogen as a main component and C
CO is selectively oxidized at a temperature that can prevent the aggregation of the water contained in the gas containing O and water, that is, at a relatively high temperature range of 100 ° C. or more, so that the CO concentration in the hydrogen gas is sufficiently increased. It is an object of the present invention to provide a catalyst for selectively oxidizing CO in hydrogen gas and a method for producing the same, which can be reduced to as low as possible.

The present invention also provides a hydrogen gas for a fuel cell in which the CO concentration is sufficiently reduced by applying the catalyst for selectively oxidizing CO in hydrogen gas. Used as fuel for low-temperature operation type fuel cells such as electrolyte type fuel cells, it is possible to prevent poisoning of the fuel electrode of the power generator by CO, and to extend the life of the cell and improve the stability of output in hydrogen gas. It is intended to provide a method for removing CO.

[0020]

According to the present invention, the catalyst for selective oxidation of CO in hydrogen gas according to the present invention is, as described in claim 1, a base metal containing a platinum group metal and a rare earth element on a surface of a ceramic integrated carrier. It is characterized in that a composite oxide of a metal is dispersed via activated alumina.

In the embodiment of the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, the platinum group metal is palladium and ruthenium. And

Similarly, in the embodiment of the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, as described in claim 3, palladium is selected from palladium chloride, palladium nitrate and dinitrodiammine palladium. It is characterized in that the ruthenium is in the form of either ruthenium chloride or ruthenium nitrate.

Similarly, in the embodiment of the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, the base metal is copper, as described in claim 4. An embodiment of the catalyst for selective oxidation of CO in hydrogen gas according to the present invention is characterized in that the rare earth metal is cerium and / or neodymium.

Similarly, in the embodiment of the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, as described in claim 6, cerium and / or neodymium in the composite oxide contains cerium oxide and / or neodymium. Alternatively, the ratio of the strongest X-ray peak of another metal oxide to the strongest X-ray peak of cerium oxide and / or neodymium oxide is 0.01 or less.

The method for producing a catalyst for selective oxidation of CO in hydrogen gas according to the present invention is, as described in claim 7, the catalyst for selective oxidation of CO in hydrogen gas according to any one of claims 1 to 6. Is characterized in that the composite oxide of a base metal containing a platinum group metal and a rare earth metal is produced via a monooxycarbonate generated by a hydrothermal reaction of a carbonate.

In a preferred embodiment of the method for producing a CO selective oxidation catalyst in hydrogen gas according to the present invention, claim 8
As described in the above, a platinum group metal obtained by co-precipitating a platinum group metal salt, a copper salt, and a rare earth metal salt by a hydrothermal reaction using heated steam and then sintering in air is used. A mixed oxide of a base metal and a rare earth metal, and an activated alumina are kneaded to form a slurry, which is applied to a ceramic integrated carrier and then fired at 350 to 500 ° C. in an oxidizing gas atmosphere. .

According to the method for removing CO from hydrogen gas according to the present invention, a mixed gas obtained by mixing oxygen with a gas containing hydrogen as a main component and containing CO is described in claim 9. So as to selectively oxidize CO by contacting with the CO selective oxidation catalyst according to any one of the above, and to convert CO into CO ₂ so as to remove CO in a gas containing hydrogen as a main component and containing CO. It is characterized by doing.

In the embodiment of the method for removing CO in hydrogen gas according to the present invention, the selective oxidation reaction of CO is carried out in a temperature range of 100 to 200 ° C. It is characterized by doing.

[0029]

The catalyst for selective oxidation of CO in hydrogen gas according to the present invention disperses a complex oxide of a base metal containing a platinum group metal and a rare earth metal and the complex oxide on the surface of a ceramic-integrated carrier. And sintering with activated alumina.

The composite oxide of a base metal containing a platinum group metal and a rare earth metal used here is such that the platinum group metal is palladium and ruthenium, the base metal is copper, and the rare earth metal is cerium and / or neodymium. it _{can, Ce x Cu y (PM)} O z or Nd _x Cu
It is preferable to use a so-called spinel-type composite oxide represented by _y (PM) _Oz (where PM: Pd + Ru).

In such a composite oxide, nitrates and / or hydrochlorides of each metal are mixed at a predetermined stoichiometric ratio, and the mixture is added to an ammonium hydrogen carbonate solution to form a carbonate, and then heated. A monooxycarbonate can be synthesized by a hydrothermal reaction in steam and fired in air to obtain a monooxycarbonate.

The activated alumina mixed and used at the same time as the composite oxide can be γ-alumina obtained by calcining boehmite alumina hydrate at a temperature of about 750 ° C. in an air stream, for example. It is desirable that the specific surface area measured by the BET method be 100 m ² / g or more.

Next, a method for producing a CO selective oxidation catalyst in hydrogen gas according to the present invention will be described.

In the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, the platinum group metal can be composed of palladium and ruthenium, the base metal can be copper, and the rare earth metal can be cerium and / or ruthenium. Or neodymium, in which case,
Palladium is one of palladium chloride, palladium nitrate, and dinitrodiammine palladium, and ruthenium is a pure platinum group metal salt of ruthenium chloride or ruthenium nitrate, copper nitrate, cerium nitrate and / or neodymium nitrate. Disperse and mix in water.

Then, the mixed solution is previously added to the autoclave while dispersing and stirring ammonium hydrogen carbonate with pure water. Next, after the entire amount is added, for example, steam at 120 ° C. is injected into the autoclave in a closed state.

The internal pressure of the autoclave is, for example, 1.1 kg
/ Cm ² when it reaches about ²
For example, the reaction is performed for about 3 hours.

After completion of the reaction, after filtration, washing and drying,
By firing at 300 ° C. for 2 hours in the air, a composite oxide of a base metal containing a platinum group metal and a rare earth metal is obtained.

Next, a slurry obtained by kneading a complex oxide of a base metal containing a platinum group metal and a rare earth metal and activated alumina with a nitric acid-acidic alumina sol is applied to a ceramic integrated carrier, and then burned in an oxidizing atmosphere. Calcination at, for example, 400 ° C. in a gas atmosphere gives a CO selective oxidation catalyst according to the present invention.

Next, the operation will be described.

A liquid fuel composed of a raw material for reforming alcohols such as methanol and water is gasified using a vaporizer, and then brought into contact with a reforming catalyst, thereby producing a hydrogen-rich gas by a steam reforming reaction described below. Obtain a suitable reformed gas.

CH ₃ OH → CO + 2H ₂ (1) CO + H ₂ O → CO ₂ + H ₂ (2) As a whole, CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (3) In the above reaction, the reaction of the formula (1) Is an endothermic reaction, it is necessary to raise the reaction temperature to improve the conversion of methanol. On the other hand, since the reaction of the formula (2) is an exothermic reaction, the reaction does not proceed under a high temperature condition and a large amount of CO remains.

Therefore, when the gas is supplied to the fuel cell as it is, the catalyst such as platinum used for the electrode is poisoned,
Since the power generation capacity is reduced, it is necessary to oxidize and remove CO in the reformed gas under a selective oxidation catalyst, for example, to reduce it to a level of several ppm.

The reformed gas may be subjected to a shift reaction (C
O + H ₂ O → H ₂ + CO ₂ ) by converting CO to CO ₂ via a shift catalyst-mediated denaturation process.
After the concentration is reduced to, for example, about several thousand ppm, it is introduced into the selective oxidation catalyst layer.

In the preferred CO selective oxidation catalyst used here, palladium and ruthenium are highly dispersed in the composite oxide of cerium and / or neodymium and copper, and the high oxygen content of rare earth oxides such as cerium and neodymium.
_{Due to the two} storage capability, palladium and ruthenium can always be kept in an oxide state without being reduced to a metal state even in a hydrogen-rich fuel gas.

As a result, the selective oxidation reaction can be carried out by sufficiently supplying the amount of air close to the theoretical amount of oxygen required for the oxidation reaction of CO and sufficiently following the fluctuation of the CO concentration.

CO is covalently bonded to an oxide such as palladium, ruthenium, and copper, and is oxidized. On the other hand, hydrogen reacts with oxygen after being ion-coordinated on the surface of the metal particles. The oxidation reaction of hydrogen does not easily proceed on the above-mentioned catalyst which maintains the above condition.

Therefore, even if the temperature of the catalyst layer rises to 100 ° C. or more due to the CO oxidation reaction which is an exothermic reaction, C
The selectivity to O does not decrease and the coordination of hydrogen on the catalytic metal does not easily occur, so that the reverse shift reaction hardly occurs.

Therefore, the CO concentration in the fuel gas does not fluctuate due to the fluctuation in the temperature of the catalyst layer, and the temperature of the outlet of the catalyst layer becomes almost equal to the temperature of the inlet due to the heat radiation effect of the ceramic integrated type carrier. There is also an effect that the fuel gas can be directly supplied to the fuel cell without using any means.

By a hydrothermal reaction using heated steam, carbonates such as cerium and neodymium partially hydrolyze a carbonate group (—CO ₃ ) to form a monooxycarbonate as shown below, Forming a physical state results in a fine crystal structure.

R ₂ O (CO ₃ ) ₃ + nH ₂ O → R ₂ O
(CO ₃ ) ₂ .H ₂ O + CO ₃ + (n-1) H ₂ O In addition, while in a hydrate state, an oxygen atom is already shared in the structure. Therefore, an oxide can be formed at a low temperature, so that the oxide can have a large specific surface area.

In order to disperse coexisting copper, palladium, ruthenium and the like in fine crystals of cerium and neodymium, the ratio of the strongest X-ray peak of another metal oxide to the strongest X-ray peak of cerium oxide and neodymium oxide is considered. Is 0.
By not more than 01, it does not undergo direct reduction by hydrogen, can maintain a highly dispersed state as an oxide for a long period of time, and also maintains selectivity to CO, and exhibits activity as a CO selective oxidation catalyst. Will continue.

[0052]

According to the catalyst for selective oxidation of CO in hydrogen gas according to the present invention, as described in claim 1, a composite of a base metal containing a platinum group metal and a rare earth metal is formed on the surface of a ceramic integrated carrier. Since the oxide was dispersed through the activated alumina, for example, even in a hydrogen-rich fuel cell fuel gas, the composite oxide containing a platinum group metal is not reduced to the metal state, If air is supplied in an amount close to the theoretical amount of oxygen required for the CO oxidation reaction in order to maintain the oxide state at all times, the selective oxidation reaction of CO can be performed sufficiently following the fluctuation of the CO concentration. Can be obtained, and a remarkably excellent effect that it is possible to obtain a hydrogen gas having a sufficiently reduced CO concentration is obtained. For example, a hydrogen-rich gas obtained by reforming methanol or the like is used. Fuel cell vehicle Enables early commercialization of systems, use and further improvement in air pollution alternative fuels is leading to Chodai Naru effect will be realized.

And, as described in claim 2,
When the platinum group metal is palladium or ruthenium, a remarkable effect that the catalytic performance as a selective oxidation catalyst for CO in hydrogen gas can be further improved can be brought about.

Further, as set forth in claim 3, palladium is in any form of palladium chloride, palladium nitrate or dinitrodiammine palladium, and ruthenium is in any form of ruthenium chloride or ruthenium nitrate. By making it possible to reduce the palladium and ruthenium to the metal state, the oxide state can be maintained for a long time, and the selective oxidation activity of CO can be stably maintained. It has a great effect of being able to do so.

Further, as set forth in claim 4, when the base metal is copper, the composite oxide of rare earth metal such as cerium and neodymium and copper and palladium and ruthenium are contained in the composite oxide. It is possible to obtain a complex oxide in which a platinum group metal is highly dispersed, and it is difficult to reduce the metal oxide to a metal state. A great effect is brought.

Furthermore, by setting the rare earth metal to be cerium and / or neodymium, the high O ₂ storage capability of the rare earth oxides such as cerium and neodymium can be achieved. The platinum group metal can be prevented from being reduced to a metal state even in a hydrogen-rich fuel gas, and can be kept in an oxide state at all times.
A remarkable effect that the selective oxidation reaction of O can be performed is brought about.

Further, as described in claim 6, cerium and / or neodymium in the composite oxide is in the form of cerium oxide and / or neodymium oxide, and X of cerium oxide and / or neodymium oxide By making the ratio of the strongest X-ray peak of the other metal oxide to the strongest peak of the line be 0.01 or less, it is difficult to receive direct reduction by hydrogen. The dispersion state can be maintained, the change over time of the selective oxidation reaction can be reduced, and a composite oxide having more excellent structural stability can be obtained. Effect is brought about.

According to the method for producing a catalyst for selective oxidation of CO in hydrogen gas according to the present invention, as described in claim 7, the selective oxidation of CO in hydrogen gas according to any one of claims 1 to 6 can be achieved. In producing the catalyst, the composite oxide of the base metal containing the platinum group metal and the rare earth metal was produced via the monooxycarbonate generated by the hydrothermal reaction of the carbonate, so that the heated steam was used. The carbonates such as cerium and neodymium are partially hydrolyzed by the hydrothermal reaction using, and a part of the carbonate group (-CO ₃ ) is hydrolyzed to form a monooxycarbonate to form a hydrate state. It is possible to make a rare earth composite oxide with a unique crystal structure,
Pd, Ru, for example, are incorporated into fine crystals of, for example, Cu—Ce, Cu—Nd, and the oxide state of PdO, RuO, etc., is stably maintained by the O ₂ storage capability of Ce, Nd. Therefore, even at a temperature of 100 ° C. or more, a remarkably excellent effect that a methanation reaction and a reverse shift reaction occurring on a metal can be suppressed is brought about.

And, as described in claim 8,
Composite oxidation of base metal and rare earth metal containing platinum group metal obtained by co-precipitating platinum group metal salt, copper salt and rare earth metal salt by hydrothermal reaction using heated steam and then firing in air Material and activated alumina are kneaded to form a slurry, which is applied to a ceramic-integrated carrier and then oxidized in an oxidizing gas atmosphere.
By firing at 50 to 500 ° C., the heat generated by the oxidation reaction can be efficiently discharged through the ceramic-integrated carrier, and the composite oxide of the base metal containing the platinum group element and the rare earth metal can be removed. The remarkable effect that it is possible to produce a catalyst for selective oxidation of CO in hydrogen gas which is excellent in catalytic performance highly dispersed via activated alumina and has little deterioration of catalytic performance with time can be produced.

According to the method for removing CO from hydrogen gas according to the present invention, a mixed gas obtained by mixing oxygen with a gas containing hydrogen as a main component and containing CO as described in claim 9 is described in claim 1 to claim 9. 6. CO is selectively oxidized by being brought into contact with the CO selective oxidation catalyst according to any one of the above (6) and CO is converted into CO ₂ to remove CO in the gas containing hydrogen as a main component and containing CO. Therefore, if air is supplied in an amount close to the theoretical amount of oxygen necessary for the oxidation reaction of CO, the selective oxidation reaction of CO can be performed sufficiently following the fluctuation of the CO concentration. A remarkably excellent effect that it is possible to obtain a hydrogen gas with a sufficiently reduced CO concentration is obtained.

As described in claim 10, by performing the selective oxidation reaction of CO in a temperature range of 100 to 200 ° C., the water contained in the gas containing CO and water can be obtained. A remarkable effect is obtained that the CO concentration in the hydrogen gas can be sufficiently reduced by selectively oxidizing CO while preventing aggregation.

[0062]

EXAMPLES Examples of the present invention will be described below together with comparative examples.

Example 1 158 g of ammonium bicarbonate was added to pure water 2 in an autoclave having a content of 1,000 ml.
Then, while stirring, 1.0 g of palladium chloride (PdCl ₂ .2H ₂ O), 1.65 g of ruthenium chloride (RuCl ₄ .5H ₂ O), copper nitrate [Cu
38.03 g of (NO ₃ ) ₂ .3H ₂ O] and 275.8 g of cerium nitrate [Ce (NO ₃ ) ₃ .6H ₂ O] in pure water 2
Then, the solution dissolved in 00 ml was gradually charged, and after the entire amount was charged, the autoclave was closed and the temperature was maintained at about 120 ° C. and steam pressure 2 kgf /
cm ² of steam, and the internal pressure of the autoclave is adjusted to 1.1.
When the pressure reached kgf / cm ² , the supply of steam was temporarily stopped.

Then, the internal pressure of the autoclave is reduced to 1.1 kg.
Stirring was continued for 3 hours while controlling the supply amount of steam so as to maintain f / cm ² , and a maximum of 1.2 kgf / cm ² , thereby completing the hydrothermal reaction.

After 3 hours, the supply of steam was completely stopped,
The airtightness was gradually released, and the mixture was cooled to room temperature while stirring was continued. After cooling, the reaction-completed slurry hydrate was taken out of the autoclave and suction-filtered to collect a precipitate. Next, the collected precipitate was washed with pure water and dried in an oven at 100 ° C. for 12 hours.

Next, the dried powder was placed in an air stream at 300 ° C.
For 2 hours to obtain a cerium-based composite oxide powder containing a platinum group metal. The weight of the composite oxide powder obtained here was 123 g according to the theoretical amount, and the specific surface area by the BET method was 120 m ² / g.

The total amount of the platinum group metal-containing cerium-based composite oxide powder and γ-alumina powder (S
Ba-200, specific surface area 180 m ² / g) 100 g,
Nitric acid acidic boehmite sol (sol obtained by adding 10% by weight of nitric acid to a 10% by weight suspension of boehmite alumina) 20
0 g was charged into a magnetic ball mill pot, and the slurry obtained by mixing and grinding was mixed with a ceramic-integrated carrier (volume: 0. 1 g).
(5 L, number of cells: 400 cells).

Thereafter, the catalyst was dried at 130 ° C. × 1 hour, and calcined at 400 ° C. × 2 hours in a combustion gas atmosphere containing sufficient oxygen to obtain a catalyst A of Example 1.

The coating amount of the oxide containing alumina of the catalyst obtained here was set to 100 g / unit on a dry weight basis. As a result, as shown in Table 1, Pd: 0.
20 g, Ru: 0.20 g, Cu: 4.2 g, Ce: 3
All of 7.1 g was supported in an oxide state.

(Example 2) In Example 1, 2.0 g of palladium chloride, 3.3 g of ruthenium chloride, and copper nitrate 3
A cerium-based composite oxide powder containing a platinum group metal was obtained in the same manner except that 8.03 g and 272.7 g of cerium nitrate were used. The weight of the composite oxide powder obtained here was 123 g according to the theoretical amount.

Using this composite oxide powder, a catalyst B was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.416 g, Ru:
0.416 g, 4.2 g of Cu, and 36.7 g of Ce were all supported in an oxide state.

(Example 3) In Example 1, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride, 1 part of copper nitrate
A cerium-based composite oxide powder containing a platinum group metal was obtained in the same manner except that 9.0 g and 291.35 g of cerium nitrate were used. The weight of the composite oxide powder obtained here was 122.9 g according to the theoretical amount.

Using this composite oxide powder, a catalyst C was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.20 g, Ru:
0.20 g, Cu: 2.08 g, and Ce: 39.2 g were all supported in an oxide state.

(Example 4) In Example 1, 2.0 g of palladium chloride, 3.3 g of ruthenium chloride, and 1 g of copper nitrate were used.
A cerium-based composite oxide powder containing a platinum group metal was obtained in the same manner except that 9.0 g and 288.3 g of cerium nitrate were used. The weight of the composite oxide powder obtained here was 122.9 g according to the theoretical amount.

Then, using this composite oxide powder, a catalyst D was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.416 g, Ru:
0.416 g, Cu: 2.08 g, and Ce: 38.8 g were all supported in an oxide state.

(Example 5) In Example 1, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride, and 3 parts of copper nitrate were used.
8.03 g, neodymium nitrate _{[Nd (NO 3) 3 ·} 6H 2
O] 270.4 g of a platinum group metal-containing neodymium composite oxide powder was obtained in the same manner except that 270.4 g was used. The weight of the composite oxide powder obtained here was 117.5 g as a theoretical amount.

Then, using this composite oxide powder, a catalyst E was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.21 g, Ru:
0.21 g, Cu: 4.28 g, and Nd: 38.0 g were all supported in an oxide state.

Example 6 In Example 1, 2.0 g of palladium chloride, 3.3 g of ruthenium chloride, and 3 g of copper nitrate were used.
A platinum group metal-containing neodymium-based composite oxide powder was obtained in the same manner except that 8.03 g and 267.4 g of neodymium nitrate were used. The weight of the composite oxide powder obtained here was 117.6 g as a theoretical amount.

Then, using this composite oxide powder, a catalyst F was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.425 g, Ru:
0.425 g, 4.27 g of Cu, and 37.5 g of Nd were all supported in an oxide state.

(Example 7) In Example 1, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride and 1 part of copper nitrate were used.
A platinum group metal-containing neodymium-based composite oxide powder was obtained in the same manner except that 9.0 g and 285.8 g of neodymium nitrate were used. The weight of the composite oxide powder obtained here was 117.2 g as a theoretical amount.

Using this composite oxide powder, a catalyst G was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.21 g, Ru:
0.21 g, Cu: 2.14 g, and Nd: 40.2 g were all supported in an oxide state.

(Example 8) In Example 1, 2.0 g of palladium chloride, 3.3 g of ruthenium chloride, and 1 g of copper nitrate were used.
A platinum group metal-containing neodymium-based composite oxide powder was obtained in the same manner except that 9.0 g and 282.7 g of neodymium nitrate were used. The weight of the composite oxide powder obtained here was 117.2 g as a theoretical amount.

Then, using this composite oxide powder, a catalyst H was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.426 g, Ru:
0.426 g, Cu: 2.14 g, and Nd: 39.7 g were all supported in an oxide state.

(Comparative Example 1) In a glass beaker having a capacity of 1,000 ml, 158 g of ammonium hydrogen carbonate was added to pure water 2
Then, with stirring, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride, and 38.0 copper nitrate.
A solution prepared by dissolving 3 g and 275.8 g of cerium nitrate in 200 ml of pure water was gradually charged, and after the entire amount was charged, stirring was continued at room temperature for 3 hours. After 3 hours, the slurry-like precipitate was taken out of the beaker and suction-filtered to collect the precipitate.

Next, the collected precipitate was washed with pure water and dried in an oven at 100 ° C. for 12 hours.

Next, the dried powder was placed in an air stream at 300 ° C.
To obtain a cerium-based oxide powder containing a platinum group metal. The weight of the obtained oxide powder was 12
3 g. The specific surface area by the BET method is 85 m.
² / g.

Using this oxide powder, Example 1
Catalyst I was obtained in the same manner as described above. As a result, as shown in Table 1, Pd: 0.20 g, Ru: 0.20
g, Cu: 4.20 g, and Ce: 37.1 g were carried in a substantially oxide state.

Comparative Example 2 In Comparative Example 1, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride, and 3 parts of copper nitrate
A platinum group metal-containing neodymium-based oxide powder was obtained in the same manner except that 8.03 g and 270.4 g of neodymium nitrate were used. The weight of the oxide powder obtained here was 11% according to the theoretical amount.
It was 7.5 g.

Using this oxide powder, Example 1
Catalyst J was obtained in the same manner as described above. As a result, as shown in Table 1, Pd: 0.21 g, Ru: 0.21
g, Cu: 4.28 g, and Nd: 38.0 g were supported in a substantially oxide state.

(Example 9) In Example 1, 1.0 g of palladium chloride, 1.65 g of ruthenium chloride, and 5 parts of copper nitrate
A cerium-based composite oxide powder containing a platinum group metal was obtained in the same manner except that 7.0 g and 260.4 g of cerium nitrate were used. The weight of the composite oxide powder obtained here was 123.2 g as a theoretical amount.

Using this composite oxide powder, a catalyst K was obtained in the same manner as in Example 1. As a result, as shown in Table 1, Pd: 0.208 g, Ru:
0.208 g, Cu: 6.25 g, and Ce: 35.5 g were all supported in an oxide state.

[0092]

[Table 1]

(Test Examples) Examples 1 to 8 and Comparative Examples 1 and 2
With respect to the catalysts A to J obtained in Step 2, the structural stability of the target composite oxide was evaluated from the time-dependent change of the CO selective oxidation reaction and the time-dependent change of the amount of CH ₄ produced under the following conditions.
It was judged.

[0094]

[Table 2]

FIG. 1 shows the result.

As shown in FIG. 1, in the catalysts I and J obtained in Comparative Examples 1 and 2, the change over time in the CO selective oxidation reaction and the CH
Against aging of ₄ production amount that fairly both large, the catalyst A~H obtained in the present invention Examples 1-8 Any time course of aging and CH ₄ production of CO selective oxidation reaction It was almost absent, and it was recognized that the structural stability of the composite oxide was remarkably good.

Next, Example 1 (catalyst A) and Example 9
The X-ray diffraction peaks of the (catalyst K) with respectively 2 and 3 show both catalysts A, the time course of aging and CH ₄ production of CO selective oxidation reaction of K in FIG.

As shown in FIG. 4, the time-dependent change of the CO selective oxidation reaction of the catalyst K and the time-dependent change of the amount of CH ₄ production are different from the time-dependent change of the CO selective oxidation reaction of the catalyst A and the time-dependent change of the CH ₄ production amount. Although not as large as the catalysts I and J of Comparative Examples 1 and 2, they are slightly larger.
From the X-ray diffraction peak diagram of each of the catalysts A and K shown in FIG. 5, the ratio of the strongest X-ray peak of another metal oxide (here, CuO) to the strongest X-ray peak of cerium oxide (or neodymium oxide) was 0.1%. It has been found that it is more desirable to be 01 or less.

[Brief description of the drawings]

FIG. 1 shows the time-dependent changes in the CO selective oxidation reaction and the time-dependent changes in the amount of CH ₄ produced for Catalysts A to H obtained in Examples 1 to 8 of the present invention and Catalysts I and J obtained in Comparative Examples 1 and 2. It is a graph which illustrates a result.

FIG. 2 is a graph illustrating the result of examining the X-ray diffraction peak of catalyst A obtained in Example 1 of the present invention.

FIG. 3 is a graph illustrating the result of examining the X-ray diffraction peak of catalyst K obtained in Example 9 of the present invention.

FIG. 4 is a graph illustrating the results of examining the change over time in the selective oxidation reaction of CO and the change over time in the amount of produced CH ₄ for catalysts A and K obtained in Examples 1 and 9 of the present invention.

Claims (10)

[Claims] 1. A catalyst for selective oxidation of CO in hydrogen gas, comprising a composite oxide of a base metal containing a platinum group metal and a rare earth metal dispersed on a surface of a ceramic integrated carrier via activated alumina. 2. The catalyst for selective oxidation of CO in hydrogen gas according to claim 1, wherein the platinum group metal is palladium and ruthenium. 3. The hydrogen gas according to claim 2, wherein palladium is in any form of palladium chloride, palladium nitrate, and dinitrodiammine palladium, and ruthenium is in any form of ruthenium chloride and ruthenium nitrate. CO selective oxidation catalyst. 4. The catalyst for selective oxidation of CO in hydrogen gas according to claim 1, wherein the base metal is copper. 5. The catalyst for selective oxidation of CO in hydrogen gas according to claim 1, wherein the rare earth metal is cerium and / or neodymium. 6. The cerium and / or neodymium in the composite oxide is in the form of cerium oxide and / or neodymium oxide, and the X-ray of another metal oxide with respect to the strongest X-ray peak of cerium oxide and / or neodymium oxide The selective oxidation catalyst for CO in hydrogen gas according to claim 5, wherein the ratio of the strongest peak is 0.01 or less. 7. The process for producing a CO selective oxidation catalyst in hydrogen gas according to claim 1, wherein a complex oxide of a base metal containing a platinum group metal and a rare earth metal is subjected to a hydrothermal reaction of a carbonate. C in hydrogen gas characterized by being produced via a monooxycarbonate produced by
A method for producing an O selective oxidation catalyst. 8. A base metal containing a platinum group metal obtained by forming a platinum group metal salt, a copper salt, and a rare earth metal salt into a coprecipitate by a hydrothermal reaction using heated steam and then firing in air. The composite oxide of a rare earth metal and active alumina are kneaded to form a slurry, applied to a ceramic-integrated carrier, and then calcined at 350 to 500 ° C. in an oxidizing gas atmosphere. A method for producing a CO selective oxidation catalyst in hydrogen gas. 9. A method of selectively oxidizing CO by bringing a mixed gas obtained by mixing oxygen into a gas containing hydrogen as a main component and containing CO into contact with the CO selective oxidation catalyst according to any one of claims 1 to 6, A method for removing CO from hydrogen gas, comprising removing CO from a gas containing hydrogen as a main component and containing CO by converting CO into CO ₂ . 10. The selective oxidation reaction of CO is carried out at 100 to 200.
The method for removing CO in hydrogen gas according to claim 9, which is performed in a temperature range of ° C.