JP2002059004A - Co removing catalyst and co removing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produe a CO removing catalyst of which the removing capacity of CO in hydrogen-containing gas is high under a low oxygen concentration condition, that is, in a low O2/CO ratio, and to provide a CO removing method using the same. SOLUTION: The CO removing catalyst for removing CO in hydrogen- containing gas is constituted by supporting Ru and an oxide of at least one kind of an element among alkaline earth elements on an inorganic oxide carrier. CO removing method using this catalyst is also disclosed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for selectively oxidizing and removing CO from a mixed gas containing hydrogen as a main component and containing CO, and a method for removing CO using the catalyst. The present invention relates to a catalyst for selectively oxidizing and removing CO in a product gas mainly composed of hydrogen obtained by reforming a production fuel, and a method for removing CO using the catalyst.

[0002]

2. Description of the Related Art Polymer electrolyte fuel cells are highly efficient and highly environmentally friendly, and have recently attracted attention as power sources for automobiles and distributed power sources. The polymer electrolyte fuel cell generates power using hydrogen as a fuel, and is characterized by a low-temperature operation type in which an operation temperature is about 100 ° C., and a Pt-based catalyst is used for an electrode. In such a low-temperature operation, the Pt-based electrode catalyst is easily poisoned by the adsorption of CO, and when the amount of CO contained in the fuel hydrogen exceeds a certain amount, the battery performance is reduced. Usually, the allowable concentration is 100 ppm or less. Because of these problems, it is preferable to use pure hydrogen as the fuel hydrogen for the polymer electrolyte fuel cell. However, from the viewpoint of infrastructure and storage, methane, LN
It is common to use a hydrogen-containing gas obtained by reforming a gas fuel such as G or LPG, or a liquid fuel such as methanol, gasoline, naphtha, or kerosene by a reaction such as steam reforming or partial oxidation. . In such a hydrogen production process, from the equilibrium between the reforming reaction and the CO shift reaction, about 1% of CO is contained in the produced hydrogen gas, and it is difficult to reduce the CO concentration to 1% or less.

[0003] As a method of reducing the CO concentration to a level that can be tolerated by the battery electrode catalyst, oxygen or an oxygen-containing gas is introduced into the reformed hydrogen-containing gas and passed through the catalyst layer.
A method of converting O into CO ₂ by an oxidation reaction has been proposed.

[0004] CO + 1 / 2O ₂ → CO ₂ (1) When air is injected as an oxygen source during the reaction (1),
There is a problem that the hydrogen-containing gas is diluted by the residual nitrogen. Further, in these catalysts and methods, when CO is oxidized with oxygen and converted into CO ₂ , a large amount of hydrogen is simultaneously oxidized with oxygen and consumed.

H ₂ + ／ O ₂ → H ₂ O (2) (2) The reaction of (2) consumes hydrogen as a fuel and reduces the fuel utilization, and the heat generated by the reaction makes it difficult to control the temperature of the catalyst layer. There is a problem. Therefore, (1)
Among the reactions of (2) and (2), a catalyst having high selectivity for the CO oxidation reaction shown in (1), that is, a catalyst having a high CO removal rate under a low O ₂ / CO ratio condition is desired. To solve these problems, for example, Japanese Patent Application Laid-Open No. Hei 5-201702 proposes an apparatus for preferentially oxidizing carbon monoxide using a catalyst in which rhodium or ruthenium is supported on a carrier. According to this embodiment, the reaction gas composed of hydrogen, CO, oxygen, and nitrogen exhibits a high CO removal rate at a temperature of 100 ° C. or less. But,
The actual hydrogen-containing gas obtained by reforming the fuel contains high-concentration water vapor and CO _2.
The catalyst of No. 702 has a problem that sufficient performance cannot be exhibited due to the presence of steam. Regarding the selectivity of the CO oxidation reaction, for example, in JP-A-11-347414, the selectivity of the CO oxidation reaction was improved by the shape selectivity of zeolite using a catalyst in which a Pt alloy was supported on a zeolite-based carrier. However, the catalyst disclosed in Japanese Patent Application Laid-Open No. 11-347414 also shows high performance and high selectivity in the gas components composed of CO, oxygen, and hydrogen described in Examples, but can be obtained by reforming a fuel containing a large amount of water vapor. Also, there is concern about the performance and durability with actual hydrogen-containing gas.

[0006]

As described above, in the conventional technology, the performance was not sufficient under the actual hydrogen-containing gas composition conditions obtained by reforming the fuel. The present invention is directed to solving the above-described problems, and is a CO removal catalyst in a gas containing hydrogen obtained by reforming various fuels. Another object of the present invention is to provide a catalyst having a high CO removal rate under a low O ₂ / CO ratio condition.

[0007]

In order to achieve the above object, the present invention has improved the performance of a conventional catalyst in which Ru is supported on a carrier, and comprises at least one of Ru and an alkaline earth element. The catalyst characterized in that an oxide of the above is supported on an inorganic oxide carrier.
This is applied to a catalyst for removing O.

In the CO removal catalyst, the component supported on the inorganic oxide carrier together with Ru is at least one oxide of alkaline earth elements. The alkaline earth element is specifically Mg, Ca, Ba, Sr, and the oxide of the alkaline earth element is MgO, CaO, BaO,
It is represented by SrO or the like. However, the form of the oxide of the alkaline earth element is not limited to this, and for example, it may contain a composite oxide of the element or oxide constituting the inorganic oxide carrier and the alkaline earth element. .

In the CO removal catalyst, the amount of the at least one oxide of the alkaline earth elements, which is a constituent ratio, may be 1 to 40 wt% of the total catalyst in terms of oxide weight. preferable. If this amount is less than 1 wt% of the whole catalyst, the effect of improving the performance of the Ru catalyst will not be exhibited, and if it is 40 wt% or more, the effect on the content will be small.

[0010] In the CO removal catalyst, the amount of supported Ru as a catalytically active component is preferably in the range of 0.05 to 5 wt%. If this amount is less than 0.05% by weight of the whole catalyst, the catalytic activity is low, and if it is 5% by weight or more, the activity per contained Ru amount is reduced due to the aggregation of Ru, and the effect of the added portion does not appear and the content is large. This increases the cost of the catalyst.

In the above CO removal catalyst, the inorganic oxide carrier includes porous alumina such as γ-alumina, θ-alumina, η-alumina, boehmite, porous alumina composite oxide containing alumina, titania, silica-alumina. A porous carrier having a high specific surface area suitable for highly dispersing and supporting a catalytically active component such as zeolite or the like can be applied. In particular, alumina or a porous alumina composite oxide containing alumina is preferable.

The catalyst for removing CO is generally in the form of pellets such as spheres and cylinders or particles, but the shape is not limited to these. The CO removal catalyst can be used as a CO removal catalyst structure obtained by coating a ceramic or metal structure, and such a structure can be a honeycomb-shaped, plate-shaped substrate, or reactor-shaped inner wall.

The catalyst for removing CO in a hydrogen-containing gas as described above is obtained by introducing oxygen or an oxygen-containing gas into a hydrogen-containing gas obtained by reforming a hydrocarbon fuel, passing the catalyst through a catalyst layer, and oxidizing CO to CO _2. Used to convert to Specifically, a means for introducing oxygen or an oxygen-containing gas is provided at the inlet of the catalyst layer filled with the CO removal catalyst, and a predetermined O ₂ / CO (molar ratio) with respect to CO in the hydrogen-containing gas. The injection amount of oxygen or an oxygen-containing gas is adjusted so as to obtain the optimum value. The catalyst layer may be one layer or two or more layers in series, but in order to obtain a high CO removal rate, two or more catalyst layers having a means for introducing oxygen or an oxygen-containing gas into each layer inlet are required. Installation is more effective. Further, when two or more catalyst layers are arranged in series, a high CO removal rate can be obtained by adjusting the value of O ₂ / CO (molar ratio) at each layer inlet so that the downstream catalyst layer is larger than the upstream catalyst layer. The effect is great. O ₂ / C
If the value of O (molar ratio) is large, the CO removal rate at the same inlet gas temperature increases, but the temperature of the catalyst layer rises due to the simultaneous oxidation of CO and the oxidation of hydrogen that proceed simultaneously, making temperature control as a system difficult. Become. Therefore, when two or more catalyst layers are provided, the calorific value of each layer is balanced by adjusting the value of O ₂ / CO (molar ratio) so that the downstream catalyst layer is larger than the upstream catalyst layer. Can be. Particularly, in the case of the above-mentioned CO removal catalyst, the removal activity at a value of O ₂ / CO (molar ratio) is higher than that of a conventional catalyst in which only Ru is supported on a carrier. Can reduce the difference in heat generation in each layer, and is also advantageous in terms of temperature control.

Next, the present invention will be described in more detail.

The method for producing the catalyst of the present invention will be described. A typical impregnation method will be described below as a method for supporting at least one oxide of at least one of Ru and alkaline earth elements constituting the catalyst on an inorganic oxide carrier. An aqueous solution or alcohol solution having a predetermined concentration adjusted by dissolving a predetermined amount of a salt of Ru and an alkaline earth element is prepared to be a catalyst raw material liquid.
This is brought into contact with and immersed in an inorganic porous carrier having various shapes such as a powder, a pellet, and a honeycomb. As the Ru salt, ruthenium chloride, ruthenium chloride hydrate, ruthenium nitrate, dichloroamino ruthenium complex, and other water-soluble and alcohol-soluble ruthenium salts and ruthenium complexes can be used. It is also possible to dilute and use a solution in which a ruthenium salt or complex is dissolved in an acid. As salts of alkaline earth elements, nitrates, sulfates, carbonates, acetates and the like can be used. A catalyst raw material solution may be prepared by mixing a Ru salt and an alkaline earth salt, and Ru and an alkaline earth oxide may be simultaneously supported on a carrier, or a Ru salt only catalyst raw material solution and an alkaline earth salt only May be separately prepared and supported step by step on a carrier. The order of loading Ru and the alkaline earth oxide on the carrier may be Ru first or later. Other than such an impregnation method, the catalyst raw material liquid can be used for production by a competitive adsorption method, a precipitation method, a kneading method, or the like. In this case, in addition to the above raw materials, hydroxides and oxides can be used as alkaline earth salt raw materials. After the catalyst raw material liquid is supported on the porous carrier by the above-described procedure, it is dried at a temperature of normal temperature or higher, preferably 100 ° C or higher, and then calcined at 300 ° C or higher, preferably 350 to 550 ° C for 1 hour or longer.

The CO removal catalyst produced by the above method is
If the shape of the inorganic oxide carrier used is a shape such as a granular shape, a pellet shape, a honeycomb shape or the like which can be directly charged into the reactor, it can be used as a completed catalyst. In addition, in addition to using the above-mentioned catalyst alone, the powder prepared by the above method is supported on a ceramic or metal structure such as a honeycomb, foam, fiber, or plate by a method such as slurry coating. It is also possible to use.

The catalyst produced by the above-mentioned production method is used by filling it in a reactor. The newly charged catalyst is directly hydrogen,
The reaction may be performed by introducing a fuel reforming gas containing CO and oxygen, but preferably a hydrogen reduction treatment is performed before the reaction. This is performed at 350 ° C. to 550 ° C. for 1 hour or more under a hydrogen stream.

Next, a method of removing CO using the above-described catalyst for removing CO will be described. A reactor provided with a means for injecting oxygen or a gas containing oxygen at the inlet side is charged with the CO removal catalyst. 300 ° C. or less, preferably 100 to
A fuel reforming gas containing hydrogen at 250 ° C. and oxygen or a gas containing oxygen are introduced into the catalyst layer by the injection means. At this time, the injection amount of oxygen or the gas containing oxygen is based on the stoichiometric amount of O ₂ required for CO oxidation from the above equation (1), and the molar ratio is based on the CO concentration in the fuel reforming gas containing hydrogen. The O ₂ / CO ratio is 0.5 or more, preferably 1.
Adjust to 0 or more. However, this is not the case when two or more layers filled with the catalyst are provided, and the O ₂ / CO ratio of the upstream catalyst layer may be 0.5 or less. When two or more layers filled with the catalyst are provided, the O ₂ / C ratio of the downstream catalyst layer is lower than the O ₂ / CO ratio value of the upstream catalyst layer.
By setting the value of the O 2 ratio large, a high CO removal rate can be realized as a whole. The above reaction is preferably operated at a normal space velocity (a value obtained by dividing the gas flow rate in the standard state of the supplied gas by the catalyst volume) in the range of 5,000 to 50,000 h ^-1 .

The CO removal catalyst of the present invention is characterized in that Ru and at least one oxide of alkaline earth elements are supported on an inorganic oxide carrier. Due to the combined effect of Ru and the alkaline earth oxide, the present catalyst has lower O ₂ compared to a conventional catalyst in which only Ru is supported on a carrier.
The CO removal performance under the condition of / CO 2 ratio was improved. According to the CO removal method using the CO removal catalyst of the present invention,
It is possible to oxidize and remove CO in the hydrogen-containing gas to sufficiently reduce the CO concentration. The CO-removing catalyst of the present invention and the hydrogen-containing gas obtained by the CO removing method using the same are used as a fuel for a fuel cell using hydrogen, in particular, as a fuel for a polymer electrolyte fuel cell of a low-temperature operation type. It can be used favorably without deterioration.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. (Example 1) A catalyst raw material solution obtained by dissolving 84.8 g of magnesium nitrate hexahydrate in 61 cc of distilled water was pulverized with a γ-alumina carrier (NKHD-24 manufactured by Sumitomo Alumina) and pulverized to 10-2 g.
The carrier was impregnated with 120 g of a mesh classified to 0 mesh, dried at 120 ° C., and calcined at 500 ° C. for 1 hour. Further, a commercially available ruthenium nitrate solution (Ru content: 3.93 wt%)
Impregnated with a catalyst raw material solution in which 6.88 g was dissolved in 79 cc of distilled water, dried at 120 ° C., and calcined at 550 ° C. for 1 hour,
Catalyst A was obtained. The supported amount of Ru of the catalyst A was 0.5 wt%, and the supported amount of magnesium was 10 w in terms of MgO.
t%. (Example 2) Catalyst B was prepared in the same manner as in Example 1, except that 56.15 g of calcium nitrate tetrahydrate dissolved in 79 cc of distilled water was used as the catalyst raw material liquid.
The supported amount of Ru of the catalyst B was 0.5 wt%, and the supported amount of calcium was 10 wt% in terms of CaO. (Example 3) Strontium nitrate 2 as a catalyst raw material liquid
Catalyst C was obtained in the same manner as in Example 1, except that 7.23 g of the compound dissolved in 96 cc of distilled water was used. The supported amount of Ru of the catalyst C was 0.5 wt%, and the supported amount of strontium was 10 wt% in terms of SrO. Example 4 Barium acetate 22.21 as a catalyst raw material liquid
Catalyst D was obtained in the same manner as in Example 1, except that g was dissolved in 96 cc of distilled water. The supported amount of Ru of the catalyst D was 0.5 wt%, and the supported amount of barium was BaO.
It is 10% by weight. (Comparative Example 1) γ-alumina carrier (NKH made by Sumitomo Alumina)
D-24) carrier 12 obtained by pulverizing and classifying the mixture into 10 to 20 mesh
0 g of a commercially available ruthenium nitrate solution (Ru content 3.93)
(wt%) in 81 cc of distilled water was impregnated with a catalyst raw material solution, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain a catalyst E. The amount of Ru supported on the catalyst E is 0.5 w
t%. (Comparative Example 2) Cerium nitrate hexahydrate 3 as a catalyst raw material liquid
Catalyst F was obtained in the same manner as in Example 1, except that a solution prepared by dissolving 3.64 g in 88 cc of distilled water was used. The supported amount of Ru of the catalyst F was 0.5 wt%, and the supported amount of cerium was 10 wt% in terms of CeO ₂ . (Comparative Example 3) Nickel nitrate hexahydrate 5 as a catalyst raw material liquid
Catalyst G was prepared in the same manner as in Example 1 except that 1.9 g dissolved in 77 cc of distilled water was used. The supported amount of Ru of the catalyst G was 0.5 wt%, and the supported amount of NiO was 1
0 wt%. (Example 5) A catalyst raw material solution 1 obtained by dissolving 40.17 g of magnesium nitrate hexahydrate in 79 cc of distilled water was pulverized with a γ-alumina carrier (NKHD-24 manufactured by Sumitomo Alumina) and pulverized.
Impregnated into 120g of carrier classified to ~ 20mesh, 120 ° C
And baked at 500 ° C. for 1 hour. Further, a commercially available ruthenium nitrate solution (Ru content: 3.93 wt.
%) Was impregnated with a catalyst raw material solution obtained by dissolving 16.11 g in 79 cc of distilled water, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain a catalyst H. Ru supported amount of catalyst H is 0.5 wt%
The supported amount of magnesium is converted to MgO, and the supported amount is 5 wt%. (Example 6) 199.8 g of magnesium nitrate hexahydrate was dissolved in 112 cc of distilled water to prepare a catalyst raw material solution. One half of this amount is used as a γ-alumina carrier (Sumitomo Alumina NK
Carrier 1 obtained by crushing HD-24) and classifying it into 10 to 20 mesh
20 g was impregnated, dried at 120 ° C., and fired at 500 ° C. for 1 hour. This operation was repeated twice. Furthermore, a commercially available ruthenium nitrate solution (Ru content 3.93 w
(t%) 18.41 g of a catalyst raw material solution in 77 cc of distilled water was impregnated, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain Catalyst I. The amount of Ru supported on the catalyst I is 0.5 w
t%, the supported amount of magnesium is 20 wt% in terms of MgO. (Example 7) 327.1 g of magnesium nitrate hexahydrate was dissolved in 150 cc of distilled water to prepare a catalyst raw material solution. One-third of this amount is used as a γ-alumina carrier (Sumitomo Alumina NK
Carrier 1 obtained by crushing HD-24) and classifying it into 10 to 20 mesh
20 g was impregnated, dried at 120 ° C., and fired at 500 ° C. for 1 hour. This operation was repeated three times. Further, a commercially available ruthenium nitrate solution (Ru content: 3.93 wt.
%) Was impregnated with a catalyst raw material solution obtained by dissolving 30.6 g in 66 cc of distilled water, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain a catalyst J. The supported amount of Ru of the catalyst J is 0.5 wt%.
And the amount of magnesium is 30 wt% in terms of MgO. (Example 8) 96 cc of distilled water was added to 10.52 g of barium acetate.
The raw material solution dissolved in the catalyst was impregnated with 120 g of a carrier obtained by pulverizing a γ-alumina carrier (NKHD-24 manufactured by Sumitomo Alumina) and classifying the carrier into 10 to 20 mesh, drying at 120 ° C.
It was baked at 0 ° C. for 1 hour. Further, the carrier was impregnated with a catalyst raw material solution obtained by dissolving 16.11 g of a commercially available ruthenium nitrate solution (Ru content: 3.93 wt%) in 79 cc of distilled water.
After drying at 0 ° C., it was calcined at 550 ° C. for 1 hour to obtain a catalyst K. The supported amount of Ru of the catalyst K was 0.5 wt%, and the supported amount of barium was 5 wt% in terms of BaO. (Example 9) 49.98 g of barium acetate was added to 196 of distilled water.
The resultant was dissolved in cc to prepare a catalyst raw material solution. A half of this amount is used as a γ-alumina carrier (NKHD-24 manufactured by Sumitomo Alumina).
Was crushed and impregnated into 120 g of a carrier classified into 10 to 20 mesh, dried at 120 ° C, and fired at 500 ° C for 1 hour. This operation was repeated twice. Further, a commercially available ruthenium nitrate solution (Ru content: 3.93 wt%) 18.4 was added to this carrier.
A catalyst raw material solution obtained by dissolving 1 g in 77 cc of distilled water was impregnated, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain a catalyst L. The supported amount of Ru of the catalyst L was 0.5 wt%, and the supported amount of barium was 20 wt% in terms of BaO. (Example 10) 89.67 g of barium acetate was added to distilled water 28
It was dissolved in 8 cc to prepare a catalyst raw material solution. One third of this amount is used as a γ-alumina carrier (NKHD-24 manufactured by Sumitomo Alumina).
Was crushed and impregnated into 120 g of a carrier classified into 10 to 20 mesh, dried at 120 ° C, and fired at 500 ° C for 1 hour. This operation was repeated three times. Further, 30.6 of a commercially available ruthenium nitrate solution (Ru content: 3.93 wt%) was added to this carrier.
g was dissolved in 66 cc of distilled water, impregnated with a catalyst raw material solution, dried at 120 ° C., and calcined at 550 ° C. for 1 hour to obtain a catalyst M. The supported amount of Ru of the catalyst M was 0.5 wt%, and the supported amount of barium was 30 wt% in terms of BaO.

The catalysts A, B, C, D, E, F, G, H, and A prepared in Examples 1 to 10 and Comparative Examples 1 to 3
For 13 types of I, J, K, L, and M, the CO removal performance was evaluated under the following reaction conditions 1 by changing the catalyst inlet gas temperature using an atmospheric pressure type catalyst evaluation device. The O ₂ / CO (molar ratio) in the inlet gas composition under the reaction condition 1 is 1. <Reaction conditions 1> Catalyst inlet gas temperature: 80 to 250 ° C Catalyst inlet gas composition: H ₂ 37%, CO ₂ 13%, CO 0.
1%, O ₂ 0.1%, H ₂ O 15%, N ₂ balance Space velocity (SV): 20,000 h ^{-1 After} each catalyst was charged into the reactor, prior to CO removal performance evaluation,
Under the flow of gas for reduction treatment with 10% hydrogen and nitrogen balance, 5
The reduction treatment was performed at 00 ° C. for 1 hour. FIG. 1 shows the CO removal performance. Table 1 summarizes the CO reduction rate at the reactor outlet at a catalyst layer temperature of 150 ° C. and 200 ° C. during the reaction as a representative example. Here, the CO reduction rate was determined by the following equation.

CO reduction rate (%) = (Inlet gas CO concentration−
Outlet gas CO concentration) ÷ Inlet gas CO concentration × 100 Comparing the CO reduction rate of each catalyst, compared to the conventional catalyst E (Comparative Example 1), which is a typical catalyst supporting only Ru,
Catalysts A, B, C, D, H, I, J, K, which are the catalysts of the present invention carrying both Ru and alkaline earth oxides,
Both L and M have a high CO reduction rate, and the effect of adding the alkaline earth oxide is recognized. Further, the catalysts F and G (Comparative Examples 2 and 3) to which elements other than the alkaline earth metals were added had lower CO reduction rates than the catalyst E (Comparative Example 1), which is a typical catalyst supporting only Ru. No additional effect is observed.

[0023]

[Table 1]

In Table 1, catalysts A, B, E, H, I,
Using the results of J, K, L, M, the catalyst layer temperature was 150 ° C.
FIG. 1 shows the relationship between the reduction rate of CO and the amount of alkaline earth oxide supported on the catalyst. FIG.
The catalysts A, H, I, and J are shown as Mg-based catalysts, and the catalysts D, K, L, and M are shown as Ba-based catalysts. The point of 0 wt% of the supported amount of the alkaline earth oxide in each system is the result of the catalyst E. According to FIG. 1, when the amount of the supported alkaline earth oxide is 40% by weight or less of the whole, there is an effect on the improvement of the CO removing performance.

For the catalyst I prepared in Example 6 and the catalyst E prepared in Comparative Example 1, the oxygen concentration and C
The relationship of the O removal performance was evaluated. Under reaction condition 2 shown below, the O ₂ concentration in the gas composition was changed, and O ₂ / CO (molar ratio) was set to 1, 2, and 3 conditions, and the CO removal performance was evaluated. <Reaction conditions 2> Catalyst inlet gas temperature: 80 to 250 ° C Catalyst inlet gas composition: H ₂ 37%, CO ₂ 13%, CO 2
0.1%, O ₂ 0.1, 0.2 or 0.3%, H ₂
O15%, N ₂ balance Space velocity (SV): 20,000 h ^{-1 After} each catalyst was charged into the reactor, prior to CO removal performance evaluation,
Under the flow of gas for reduction treatment with 10% hydrogen and nitrogen balance, 5
The reduction treatment was performed at 00 ° C. for 1 hour. O ₂ / C of each catalyst
FIG. 2 shows the relationship between O (molar ratio) and the CO removal rate at a catalyst layer temperature of 150 ° C. The catalyst I of the present invention has a higher CO removal activity in a region where O ₂ / CO (molar ratio) is small, that is, in a low oxygen concentration, as compared with the conventional catalyst E.

The catalyst C of Example 3 was charged into a CO remover,
The CO removal performance was evaluated. FIG. 3 shows the configuration of the CO remover used. The reaction vessel 2 of the CO remover includes 1-a, 1-
It is composed of three catalyst layers b and 1-c. The processing gas is introduced from the reaction gas introduction pipe 3 to the CO remover, and the gas processed by the catalyst layer is discharged from the outlet pipe 4. 1-
The air required for the oxidation of CO into the three catalyst layers a, 1-b, and 1-c are air injection pipes 5-a, 5-b, and 5-c, respectively.
Injected from. The catalyst layers 1-a, 1-b, 1-c are filled with the catalyst C, and the gas under the reaction condition 3 is supplied to the reaction gas introduction pipe 3.
From 5 L / min. The catalyst was charged so that the space velocity condition of the catalyst was 20,000 h ^-1 with respect to the inlet gas.
0.175 L / min from air injection pipe 5-a, 0.525 L / min from 5-b, 0.525 L / min from 5-c
Air was injected. Outlet piping 4 30 minutes after the start of operation
Measurement of the CO concentration in the gas discharged from
ppm. <Reaction Condition 3> Catalyst 1-a inlet gas temperature: 150 ° C. Catalyst inlet gas composition: H ₂ 37.4%, CO ₂ 13.5%,
CO 0.7%, H ₂ O 13.3%, N ₂ 35.1%

[0027]

As described above, the catalyst of the present invention, when removing CO in the hydrogen-containing gas, has a lower oxygen concentration than the conventional catalyst, that is, a reaction having a low O ₂ / CO molar ratio as compared with the conventional catalyst. Under the conditions, the CO removal performance is high, and the CO concentration can be reduced. Therefore, by using the present catalyst and the CO removal method using the present catalyst, it is effective to prevent performance degradation due to CO poisoning of the electrode catalyst of the hydrogen electrode of the polymer electrolyte fuel cell (PEFC).

[Brief description of the drawings]

FIG. 1 shows the relationship between the amount of alkaline earth oxide carried on a catalyst and the CO removal rate.

FIG. 2 is a graph showing CO removal ratios of catalyst I of Example 6 and catalyst E of Comparative Example 1 at O ₂ / CO molar ratios in respective processing gases.

FIG. 3 is a configuration of a CO remover.

[Description of Signs] 1-a, 1-b, 1-c: catalyst layer, 2: reaction vessel, 3 ...
Piping for introducing reaction gas, 4 ... outlet piping, 5-a, 5-b,
5-c ... air injection pipe.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H01M 8/10 H01M 8/10 (72) Inventor Sadao Takahashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Electric Power and Electricity Development Laboratory (72) Inventor Toshio Yamashita 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Electric Power and Electricity Development Laboratory F-term (reference) 4G040 EB31 4G069 AA03 AA08 AA09 BA01A BA01B BB12B BB12C BC08A BC09A BC09B BC09C BC10A BC10B BC10C BC12A BC12B BC12C BC13A BC13B BC13C BC70A BC70B BC70C CC26 DA06 EA02Y FA02 FB14 4H060 AA01 AA04 BB11 ACO2 5A02 5

Claims (9)

[Claims] 1. A catalyst for removing CO in a hydrogen-containing gas, comprising Ru and an oxide of at least one of alkaline earth elements supported on an inorganic oxide carrier. 2. The method according to claim 1, wherein the alkaline earth metal is Mg, Ca, Sr, B
The catalyst for removing CO in a hydrogen-containing gas according to claim 1, which is at least one or more selected from a. 3. The catalyst for removing CO in a hydrogen-containing gas according to claim 1, wherein the amount of supported Ru is 0.05 to 5 wt%. 4. The catalyst for removing CO in a hydrogen-containing gas according to claim 1, wherein the carried amount of at least one oxide of alkaline earth elements is 1 to 40% by weight. 5. The catalyst for removing CO in a hydrogen-containing gas according to claim 1, wherein the inorganic oxide carrier is alumina or a composite oxide containing alumina. 6. A catalyst structure for removing CO in a hydrogen-containing gas, wherein the catalyst for removing CO according to claim 1 is coated on a ceramic or metal structure. 7. A catalyst layer filled with the catalyst for removing CO in a hydrogen-containing gas according to claim 1, wherein a treatment gas and oxygen or a gas containing oxygen are injected at an inlet of the catalyst layer. To remove CO from a hydrogen-containing gas. 8. A catalyst gas comprising two or more catalyst layers filled with the catalyst for removing CO in a hydrogen-containing gas according to claim 1, wherein a processing gas is introduced from an upstream catalyst layer inlet, and oxygen is introduced at each catalyst layer inlet. Alternatively, a method for removing CO from a hydrogen-containing gas, comprising injecting a gas containing oxygen. 9. The hydrogen-containing gas according to claim 8, wherein the value of O ₂ / CO (molar ratio) in the gas introduced into each catalyst layer is larger in the downstream catalyst layer than in the upstream catalyst layer. CO removal method.