JP2002370028A - Method for producing ruthenium catalyst by using oxygen-containing ruthenium compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method not suffering a decrease in an amount of supported ruthenium in producing a residual-chlorine-free ruthenium catalyst by using an oxygen-containing ruthenium compound. SOLUTION: The ruthenium catalyst production method comprises the steps of allowing a carrier to carry an oxygen-containing ruthenium compound, drying the carrier at a temperature at which the oxygen dissociated from the oxygen- containing ruthenium compound does not react with ruthenium, and reducing the ruthenium compound carried by the carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a CO concentration reducing catalyst, and more particularly to a method for producing a CO concentration reducing catalyst using oxygen-containing ruthenium.

[0002]

2. Description of the Related Art Polymer electrolyte fuel cells (hereinafter referred to as "PEF").
C)), gasoline, methanol, natural gas, or the like is used as a fuel source, and these are converted into hydrogen-rich reformed gas in a reformer for reasons of safety and infrastructure. A method has been proposed.

[0003] However, since the reformed gas contains a considerable concentration of CO in addition to hydrogen, the CO acts as a catalyst poison for platinum used as a catalyst of the PEFC, so that the CO concentration is reduced as much as possible. It is desired.

[0004] CO contained in the reformed gas can be selectively removed using ruthenium as a catalyst, and a halogen-containing ruthenium such as ruthenium chloride is used for reasons such as dispersibility and ease of loading. It is general to prepare a catalyst for reducing the CO concentration.

However, as disclosed in Japanese Patent Application Laid-Open No. Hei 10-29803, there is a problem that the chlorine remaining in the catalyst deteriorates the CO concentration reduction performance.
Chlorine residue also causes corrosion in the fuel system.
In addition, the 50th Annual Meeting of the Chemical Society of Japan, 1X26, 1X2
7 (1985), chlorine in the catalyst is difficult to remove even at high hydrogen reduction temperatures.

[0006]

The present inventors have attempted to produce a catalyst using a ruthenium compound containing no chlorine in order to eliminate the residual chlorine. However, when a catalyst was produced using ruthenium containing oxygen such as ruthenium nitrate or ruthenium acetate, a problem was found that the amount of ruthenium produced was much lower than the theoretical value. That is, when a catalyst is produced using oxygen-containing ruthenium,
It has been found that ruthenium volatilizes even at about 100 ° C., and the amount of ruthenium supported on the carrier decreases.

Accordingly, an object of the present invention is to provide a method for producing a ruthenium catalyst having no residual chlorine by using an oxygen-containing ruthenium compound, in which the amount of supported ruthenium does not decrease.

[0008]

According to the present invention, the reaction between dissociated oxygen derived from oxygen-containing ruthenium and ruthenium can be suppressed by controlling the drying temperature and atmosphere after supporting the oxygen-containing ruthenium on a carrier, This has been completed by focusing on the fact that the volatilization of ruthenium can be suppressed.
In addition, the inventors have found that the flow rate and the flow rate of the atmospheric gas can greatly affect the catalyst performance when reducing the oxygen-containing ruthenium, and the present invention has been completed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For example, when ruthenium is supported on a carrier using ruthenium nitrate, if the carrier is dried at a high temperature of several hundred degrees Celsius, as described above, the amount of ruthenium after drying is reduced to the amount of ruthenium before drying. It is reduced by about 20% by mass. This is because the impregnated ruthenium nitrate (present as nitric acid solution) has the following formula (1):

[0010]

Embedded image

The reaction is caused by ruthenium tetroxide and volatilization. Nitric acid (HNO ₃ ), which reacts with ruthenium nitrate, is commonly added to stabilize ruthenium nitrate. The generated nitrogen dioxide (NO ₂ ) is generated by decomposition of ruthenium nitrate and NO ₃ ⁻ derived from nitric acid, and the dissociated oxygen generated at this time reacts with ruthenium,
Ruthenium tetroxide (RuO ₄ ) is produced. In the present invention, dissociated oxygen refers to oxygen generated by decomposition of an oxygen-containing ruthenium compound.

[0012] Therefore, NO ₃ from ruthenium nitrate and nitric acid in the present invention ^- drying at a temperature at which the temperature does not cause degradation of or, and ruthenium tetroxide even if degradation occurs in dissociated oxygen is generated does not occur By doing
It prevents ruthenium from volatilizing. That is, the present invention provides a step of supporting an oxygen-containing ruthenium compound on a carrier, a step of drying the carrier at a temperature at which the dissociated oxygen of the oxygen-containing ruthenium compound does not react with ruthenium, and a step of supporting the dried carrier. Reducing the ruthenium compound. Hereinafter, the ruthenium catalyst production method will be described in order.

First, an oxygen-containing ruthenium compound is supported on a carrier.

The oxygen-containing ruthenium compound is a ruthenium compound containing an oxygen atom, such as ruthenium nitrate and ruthenium acetate. In some cases, two or more ruthenium compounds may be used in combination. Various refractory inorganic oxides can be used as the carrier, and specifically, alumina, titania, silica, zirconia and the like can be used. These are widely used as catalyst carrier components, and are easy to obtain raw materials, to manufacture and handle carriers.

In carrying, first, a desired oxygen-containing ruthenium compound is dissolved in water or the like to prepare a solution. This preparation is used to support a carrier by an impregnation method, a coprecipitation method, a competitive adsorption method or the like. The treatment conditions may be appropriately selected according to various methods.
The carrier is brought into contact with the catalyst preparation solution for a period of from minutes to 10 hours.

It is also possible to improve the performance as a catalyst by adding other components.
It is also possible to add a heat conductive material such as copper, aluminum, activated carbon, silicon nitride, silicon carbide, etc. for the purpose of suppressing the consumption of hydrogen due to the regeneration and methanation reaction, and to quickly remove the reaction heat. is there. In addition, metals other than ruthenium may be supported together, and such embodiments are also included in the technical scope of the present invention. For example, platinum can be supported in addition to ruthenium,
Dinitrodiaminoplatinum and the like can be used.

Next, the carrier supporting the oxygen-containing ruthenium compound is dried at a temperature at which the dissociated oxygen of the oxygen-containing ruthenium compound does not react with ruthenium. The temperature at which the dissociated oxygen does not react with ruthenium can be determined from the amount of ruthenium carried after drying. That is, when a substantial decrease in ruthenium content cannot be confirmed during drying, it can be said that the temperature is such that dissociated oxygen and ruthenium do not react. As an atmosphere for drying, air, nitrogen, helium or argon, or a mixed gas thereof, hydrogen, or a mixed gas of hydrogen and nitrogen, helium or argon can be used. The mixed gas may be a combination of three or more of these. When drying is performed in an atmosphere containing hydrogen gas, even if the oxygen-containing ruthenium compound is decomposed by drying, the generated dissociated oxygen reacts with hydrogen, so that the production of ruthenium tetroxide can be suppressed. However, due to the danger of explosion, care must be taken not to include oxygen gas when using hydrogen gas as atmospheric gas. In the present invention, the “atmosphere gas” refers to a gas occupying 80% by volume or more of the surrounding gas, more preferably 90% by volume or more, and even more preferably 95% by volume or more. It is particularly preferably 100% by volume.

When air, nitrogen, helium or argon or a mixed gas thereof is used as an atmosphere gas, if the drying temperature is too low, the drying cannot be performed sufficiently, and there is a possibility that the productivity may be reduced. For this reason, the temperature at which no reaction occurs is preferably 40 ° C. or more,
It is more preferable that the temperature is 80 ° C. or higher. On the other hand, if it is too high, a reaction between dissociated oxygen and ruthenium may occur.
For this reason, the temperature at which no reaction occurs is preferably 100 ° C. or lower, more preferably 90 ° C. or lower.

In the case of drying in an atmosphere of hydrogen or a mixed gas of hydrogen and nitrogen, helium or argon, the reaction between dissociated oxygen and ruthenium can be more suitably suppressed as described above, but if the drying temperature is too high, During the drying, the reduction reaction by hydrogen may proceed. For this reason, the drying temperature is preferably 40 to 90 ° C, and 60 to 8 ° C.
The temperature is more preferably 0 ° C.

Although the drying time is not particularly limited, it is 2 to 70 hours in consideration of a reduction in catalyst quality due to insufficient drying, a reduction in productivity due to excessive drying, and a reaction between ruthenium and dissociated oxygen. preferable.

The drying method is not particularly limited.
Various known techniques can be used. Specifically, natural drying, evaporation to dryness, a rotary evaporator, a blow dryer, or the like can be used.

Finally, the ruthenium compound supported on the dried carrier is reduced. In the present invention, "reducing the carrier" actually means a treatment for reducing the metal compound contained in the carrier.

When performing the reduction treatment, it must be noted that if the flow rate and the flow rate of the atmospheric gas are insufficient, the catalytic performance of the obtained ruthenium catalyst may be reduced. Upon reduction of the ruthenium compound, the following formula (2):

[0024]

Embedded image

Oxygen is generated by the thermal decomposition of the ruthenium compound. At this time, if there is no molecule such as hydrogen bonded to oxygen in the immediate vicinity, this oxygen reacts with ruthenium (metal) again, and ruthenium oxide (RuO ₂ )
Will be. The generated ruthenium oxide can be reduced with hydrogen gas. However, the ruthenium (metal) reduced and generated from the ruthenium oxide tends to have a large crystallite size, which may cause a significant decrease in catalytic performance. Therefore, it is preferable to immediately remove oxygen generated by the thermal decomposition of the ruthenium compound, and it is preferable to remove hydrogen as water using hydrogen. The hydrogen-containing atmosphere gas is preferably hydrogen or a mixed gas of hydrogen and nitrogen, helium or argon, and the volume ratio of hydrogen is preferably 10% by volume or more. Also,
When performing a reduction treatment using an atmosphere gas containing hydrogen, it is effective to control the flow rate and flow rate of the atmosphere gas containing hydrogen. In order to effectively prevent the recombination of the generated oxygen and ruthenium by accelerating the physical transfer of oxygen, the flow rate of the atmospheric gas supplied per 1 g of the catalyst must be 50 ml · min ⁻¹ · g ^−1. As described above, the flow rate of the atmosphere gas is preferably set to 150 cm · min ⁻¹ or more. The upper limits of the flow rate and the flow rate are not particularly limited, but considering that the flow rate and the flow rate are unnecessarily increased and a corresponding effect cannot be obtained, each is set to 500 ml · min ⁻¹ · g ^−1. Below, 100
Suitably, it is 0 cm · min ⁻¹ or less. The reduction treatment is preferably performed at a temperature equal to or higher than the decomposition temperature of the ruthenium compound, and is preferably performed at about 350 to 600 ° C. depending on the decomposition temperature of the ruthenium compound to be used. An appropriate reduction treatment time is 1 to 6 hours. It should be noted that the flow rate of the atmospheric gas means the flow rate in a portion where the catalyst exists.

[0026]

The present invention will be described below with reference to examples and comparative examples.

<Examples 1 to 6: Drying in air atmosphere, drying temperature 100 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This is dried for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours and 70 hours) in an air atmosphere at 100 ° C., and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And a ruthenium catalyst (Examples 1 to 6). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was approximately 2.00% by mass. Table 1 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0029]

[Table 1]

<Examples 7 to 12: Drying under air atmosphere
Drying temperature 90 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in a 90 ° C. air atmosphere for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours and 70 hours), and then reduced by exposing it to a 400 ° C. hydrogen atmosphere. And ruthenium catalysts (Examples 7 to 12). The amount of supported ruthenium relative to the total amount of alumina and ruthenium after reduction was 2.00% by mass. Table 2 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0032]

[Table 2]

<Examples 13 to 18: Drying in air atmosphere, drying temperature 70 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in an air atmosphere at 70 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And a ruthenium catalyst (Examples 13 to 18). The amount of supported ruthenium relative to the total amount of alumina and ruthenium after reduction was 2.00% by mass. Table 3 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0035]

[Table 3]

Examples 19 to 24: Drying in a hydrogen atmosphere, drying temperature 90 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried under a hydrogen atmosphere at 90 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a 400 ° C. hydrogen atmosphere. And ruthenium catalysts (Examples 19 to 24). The amount of supported ruthenium relative to the total amount of alumina and ruthenium after reduction was 2.00% by mass. Table 4 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0038]

[Table 4]

<Examples 25 to 30: Drying in a hydrogen atmosphere, drying temperature 70 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried under a hydrogen atmosphere at 70 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And a ruthenium catalyst (Examples 25 to 30). The amount of supported ruthenium relative to the total amount of alumina and ruthenium after reduction was 2.00% by mass. Table 5 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0041]

[Table 5]

<Comparative Examples 1 to 6: Drying in air atmosphere, drying temperature of 110 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in an air atmosphere at 110 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And ruthenium catalysts (Comparative Examples 1 to 6). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was less than 2.00% by mass. Table 6 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0044]

[Table 6]

<Comparative Examples 7 to 12: Drying under air atmosphere
Drying temperature 130 ° C.> Activated alumina (490 g) was impregnated with an aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in an air atmosphere at 130 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And ruthenium catalysts (Comparative Examples 7 to 12). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was less than 2.00% by mass. Table 7 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0047]

[Table 7]

<Comparative Examples 13 to 18: Drying in air atmosphere, drying temperature 150 ° C.>
An aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid was impregnated. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in an air atmosphere at 150 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And ruthenium catalysts (Comparative Examples 13 to 18). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was less than 2.00% by mass. Table 8 shows the results. The amount of ruthenium supported is
It was measured by plasma emission spectroscopy.

[0050]

[Table 8]

<Comparative Examples 19 to 24: Drying in air atmosphere, drying temperature 170 ° C.>
An aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid was impregnated. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried in an air atmosphere at 170 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposure to a hydrogen atmosphere at 400 ° C. And ruthenium catalysts (Comparative Examples 19 to 24). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was less than 2.00% by mass. Table 9 shows the results. The amount of ruthenium supported is
It was measured by plasma emission spectroscopy.

[0053]

[Table 9]

<Comparative Examples 25 to 30: Drying under a nitrogen atmosphere, drying temperature of 150 ° C.>
An aqueous solution (263 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid was impregnated. At this time, the content of ruthenium relative to the total amount of alumina and ruthenium was 2.00% by mass.

This was dried under a nitrogen atmosphere at 150 ° C. for a predetermined time (2 hours, 4 hours, 10 hours, 20 hours, 40 hours, and 70 hours), and then reduced by exposing it to a hydrogen atmosphere at 400 ° C. And ruthenium catalysts (Comparative Examples 25 to 30). The amount of supported ruthenium based on the total amount of alumina and ruthenium after reduction was less than 2.00% by mass. Table 10 shows the results. The amount of ruthenium carried was measured by plasma emission spectroscopy.

[0056]

[Table 10]

It was dried in an air atmosphere for 70 hours.
The amount of ruthenium supported after drying at
FIG. 1 shows the results of the measurement. Dry as shown in the figure
When the temperature is 100 ° C or less, the decrease in the amount of ruthenium carried
Could be suppressed. That is, even if the drying temperature is below 100 ° C
For example, by the decomposition of an oxygen-containing ruthenium compound, RuO
_FourIt has been shown that the occurrence of phenomena can be suppressed.

<Examples 31 to 33: Reduction treatment with 100% by volume hydrogen atmosphere gas> Activated alumina (477.5)
g), dinitrodiaminoplatinum (platinum amount 12.5 g),
An aqueous solution (50 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid was impregnated. At this time, the content of ruthenium with respect to the total amount of alumina, platinum and ruthenium was 2.00% by mass, and the content of platinum with respect to the total amount of alumina, platinum and ruthenium was 2.50% by mass.

This is heated at 90 ° C. in a hydrogen atmosphere for 20 minutes.
After drying for a period of time, the apparatus was set in a reduction apparatus (inner diameter of reduction cylinder: 105 mm, height: 210 mm) shown in FIG.
Subsequently, a predetermined amount of 100% by volume hydrogen gas (flow rate: 150 cm / min, 250 cm /
min, 500 cm / min; flow rate 13 L / min, 21.6 L / min, 43.2 L /
min) and a reduction treatment was performed for 2 hours at a temperature of the reduction device of 500 ° C. Therefore, the flow rate per gram of catalyst is
For Example 31, it was 65 ml · min ⁻¹ · g ⁻¹ , and for Example 32, it was 108 ml · min ⁻¹ · g ^−1.
For Example 33, 216 ml · min ⁻¹ ·
g- ¹ . The CO reduction performance of the reduced ruthenium catalyst was investigated using a microreactor. The gas composition used was 16.6% by volume of CO _2, 50% by volume of H ₂ ,
CO was 1% by volume, O ₂ was 2.25% by volume, and the others were He (the same applies hereinafter). Table 11 shows the results. FIG. 3 shows a schematic diagram of a microreactor for reference.

[0060]

[Table 11]

<Examples 34 to 36: Reduction treatment with 50% by volume of hydrogen gas + 50% by volume of helium gas> On activated alumina (477.5 g), dinitrodiaminoplatinum (amount of platinum: 12.5 g), ruthenium nitrate (amount of ruthenium: 10 g) )
And an aqueous solution (50 g) containing 10% nitric acid. At this time, the content of ruthenium with respect to the total amount of alumina, platinum and ruthenium was 2.00% by mass, and the content of platinum with respect to the total amount of alumina, platinum and ruthenium was 2.50% by mass.

This is carried out under a hydrogen atmosphere at 90 ° C. for 20 minutes.
After drying for a period of time, the apparatus was set in a reduction apparatus (inner diameter of reduction cylinder: 105 mm, height: 210 mm) shown in FIG.
Subsequently, a predetermined amount of 50% by volume hydrogen gas + 50% by volume helium gas with respect to the catalyst (200 g) (flow rate: 225 cm
/ Min, 374 cm / min, 749 cm / min;
Flow rate of 19.5 L / min, 32.
(4 L / min, 64.8 L / min), and the reduction treatment was performed at a temperature of the reduction device of 500 ° C. for 2 hours. Therefore, the flow rate per gram of the catalyst was 9 for Example 34.
It is 7.5 ml · min ⁻¹ · g ⁻¹ , for Example 35 it is 162 ml · min ⁻¹ · g ⁻¹ , and for Example 36 it is 324 ml · min ⁻¹ · g ⁻¹ . The CO reduction performance of the reduced ruthenium catalyst was investigated using a microreactor. Table 12 shows the results.

[0063]

[Table 12]

<Examples 37 to 39: Reduction treatment with 10% by volume hydrogen gas + 90% by volume helium gas> Dinitrodiaminoplatinum (platinum amount: 1) was added to activated alumina (475 g).
2.5 g), an aqueous solution (50 g) containing ruthenium nitrate (10 g of ruthenium) and 10% nitric acid.
At this time, the content of ruthenium relative to the total amount of alumina, platinum and ruthenium was 2.00% by mass, and the content of platinum relative to the total amount of alumina, platinum and ruthenium was 2.50% by mass.

This is carried out under a hydrogen atmosphere at 90 ° C. for 20 minutes.
After drying for a period of time, the apparatus was set in a reduction apparatus (inner diameter of reduction cylinder: 105 mm, height: 210 mm) shown in FIG.
Subsequently, a predetermined amount of 10% by volume hydrogen gas + 90% by volume helium gas with respect to the catalyst (200 g) (flow rate: 250 cm)
/ Min, 500cm / min, 1000cm / mi
n; flow rate 21.6 L / min for the entire reduction device, 4
(3.2 L / min, 86.4 L / min), and the reduction treatment was performed for 2 hours with the temperature of the reduction device set to 500 ° C. Accordingly, the flow rate per catalyst 1g, for Example 37 is a 108ml · min ^-1 · g ^-1, for Example 38 is a ^{216ml · min -1 · g -1,} 432ml · for Example 39 min ^-1 · g ^-1 . The CO reduction performance of the reduced ruthenium catalyst was investigated using a microreactor. Table 13 shows the results.

[0066]

[Table 13]

The embodiment of the present invention configured as described above has the following effects.

In the embodiment of the present invention, when ruthenium is supported on a carrier using an oxygen-containing ruthenium compound, drying is performed at a temperature at which dissociated oxygen derived from the oxygen-containing ruthenium compound does not react with ruthenium during drying. As a result, generation of RuO ₄ can be suppressed, and a decrease in the amount of ruthenium carried due to volatilization of ruthenium can be suppressed.
Further, since no ruthenium remains in the ruthenium catalyst prepared by this method, when used as a catalyst for reducing the concentration of CO, an excellent CO oxidation removing ability can be exhibited.

Further, in the embodiment of the present invention, by controlling the drying temperature in an atmosphere of air, nitrogen, helium or argon or a mixed gas thereof, it is possible to further reduce the amount of ruthenium carried due to the volatilization of ruthenium. It is possible to favorably suppress the production and increase the productivity of the ruthenium catalyst.

In the embodiment of the present invention, the decrease in the amount of ruthenium carried due to the volatilization of ruthenium is controlled by controlling the drying temperature in an atmosphere of hydrogen or a mixed gas of hydrogen and nitrogen, helium or argon. In addition to being able to suitably control, the progress of the reduction reaction by hydrogen can be suppressed.

In the embodiment of the present invention, ruthenium can be suitably supported by using ruthenium nitrate or ruthenium acetate as the oxygen-containing ruthenium.

In the embodiment of the present invention, by setting the drying time to 2 to 70 hours, the catalyst quality is reduced due to insufficient drying, and the productivity is reduced due to excessive drying. Reaction with oxygen can be suppressed.

In the embodiment of the present invention, the flow rate is 150 to 1000 cm · min ⁻¹ and the flow rate is 50 to 1000 cm · min ^−1.
ml · min ^-1 · g ^-1 or more 500ml · min ^-1 · g ^-1
By reducing the oxygen-containing ruthenium compound at a temperature equal to or higher than the temperature at which the oxygen-containing ruthenium compound decomposes using the following hydrogen-containing atmosphere gas, a catalyst having excellent catalytic performance can be obtained.

In the embodiment of the present invention, a ruthenium catalyst having excellent catalytic performance can be obtained by reduction in an atmosphere of air, nitrogen, helium or argon or a mixed gas thereof.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the drying temperature and the amount of ruthenium carried after drying when drying is performed for 70 hours in an air atmosphere.

FIG. 2 is a schematic diagram of a reduction device used for a reduction process.

FIG. 3 is a schematic diagram of a microreactor used for evaluating CO reduction performance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/06 H01M 8/06 G 8/10 8/10 F term (Reference) 4G040 EB32 4G069 AA03 AA08 BA01B BB12C BC70A BC70B BC70C BC75B CC26 DA05 FA01 FA02 FB14 FB16 FB44 FB57 FC02 FC06 FC07 5H026 AA06 5H027 AA06 BA16

Claims (9)

[Claims] 1. a step of supporting an oxygen-containing ruthenium compound on a carrier; a step of drying the carrier at a temperature at which dissociated oxygen of the oxygen-containing ruthenium compound does not react with ruthenium; Reducing the ruthenium compound. 2. The method according to claim 1, wherein the atmosphere gas in the drying step is air, nitrogen, helium or argon or a mixed gas thereof, and the non-reactive temperature is 40 to 100 ° C. Catalyst production method. 3. The method according to claim 2, wherein the temperature at which the reaction does not occur is 80 to 90 ° C. 4. The method according to claim 1, wherein the atmosphere gas in the drying step is hydrogen or a mixed gas of hydrogen and nitrogen, helium or argon, and the non-reactive temperature is 40 to 90 ° C. The method for producing a catalyst according to the above. 5. The method according to claim 4, wherein the temperature at which the reaction does not occur is 60 to 80 ° C. 6. The method for producing a catalyst according to claim 1, wherein the oxygen-containing ruthenium compound is ruthenium nitrate or ruthenium acetate. 7. The method according to claim 1, wherein the drying is performed for 2 to 70 hours. 8. The reducing step, wherein the flow rate is 150 to 1
000cm · min ^-1And the flow rate is 50 ml min
^-1・ G^-1500ml min^-1・ G^-1Water that is
Ruthenium supported by a carrier containing an atmosphere gas containing nitrogen
The oxygen-containing compound.
Treat at a temperature higher than the temperature at which the ruthenium compound decomposes.
The touch according to any one of claims 1 to 7, wherein
Medium production method. 9. The method according to claim 8, wherein the hydrogen-containing atmosphere gas is hydrogen or a mixed gas of hydrogen and nitrogen, helium, or argon.