JP2011072934A - PtRu/C CATALYST HAVING CONTROLLED ALLOYING DEGREE AND DISPERSIBILITY AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PtRu/C catalyst for fuel cell anodes, which has the CO tolerance better than those of the conventional PtRu/C catalysts and to provide a method for producing the PtRu/C catalyst for fuel cell anodes. <P>SOLUTION: The method for producing the PtRu/C catalyst comprises: a Ru deposition step of depositing ruthenium on a platinum catalyst obtained by depositing platinum on a carrier comprising a carbon material; and a heat treatment step of heat-treating an object, which is to be treated and is obtained at the Ru deposition step, in the presence of hydrogen gas to obtain the PtRu/C catalyst. At the heat treatment step, the temperature of the object to be treated is adjusted so that the maximum temperature thereof is within 750-1,000°C and the time when the temperature thereof is ≥750°C is within 15-300 seconds. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a catalyst used for an anode of a polymer electrolyte fuel cell. More specifically, the present invention contains a support made of a carbon material, platinum and ruthenium supported on the support, and has excellent carbon monoxide resistance. The present invention relates to a PtRu / C catalyst and a method for producing the same.

The polymer electrolyte fuel cell can achieve high energy efficiency as compared with the conventional power generation technology, and thus is expected to be put to practical use as a power generation source with a low environmental load. When hydrogen is supplied to the anode (fuel electrode) of the polymer electrolyte fuel cell and air is supplied to the cathode (air electrode), the following reaction occurs. That is, hydrogen ions (protons) are generated in the fuel electrode by the action of the anode catalyst, and protons and oxygen that have passed through the electrolyte membrane are combined to generate water in the air electrode.
Fuel electrode: H ₂ → 2H ⁺ + 2e ⁻
Air electrode: 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O

  Hydrogen as a fuel is often produced by steam reforming natural gas. Hydrogen produced by this method contains a trace amount of carbon monoxide (CO), and it is known that CO is adsorbed on the anode catalyst to lower the catalytic activity. Therefore, various efforts are being made toward the development of an anode catalyst with high CO resistance.

  Among the catalysts developed so far, a catalyst in which platinum and ruthenium are supported on carbon fine particles (PtRu / C catalyst) is known to have the most excellent CO resistance (Patent Documents 1-4 and non-patent documents). Reference 1). Patent Document 1 describes a method for producing an alloy catalyst in which Pt and Ru are alloyed by heat treatment. Patent Documents 2 and 3 examine the relationship between the size of metal particles and CO resistance, and Patent Document 4 and Non-Patent Document 1 discuss the relationship between the composition ratio of Pt and Ru and CO resistance.

Japanese Patent No. 3839961 US Pat. No. 6,664,410 US Pat. No. 6,0079,34 US Pat. No. 6,339,038

Tada et al., “Effect of Composition Ratio of Thermally Diffused Platinum Ruthenium Alloy Catalyst on Carbon Monoxide Toxic Properties”, Journal of the Electrochemical Society, 2008, 76, No. 11, p. 813-823

  However, the conventional PtRu / C catalyst is not yet sufficient in CO resistance, and further improvement in CO resistance is required for practical use of the polymer electrolyte fuel cell. This invention is made | formed in view of the said situation, and it aims at providing the PtRu / C catalyst which has the CO tolerance outstanding compared with the conventional PtRu / C catalyst, and its manufacturing method.

  The method for producing a PtRu / C catalyst according to the present invention is obtained through a Ru supporting step of further supporting ruthenium on a platinum catalyst in which platinum is supported on a support made of a carbon material, and a Ru supporting step in the presence of hydrogen gas. A heat treatment step of obtaining a PtRu / C catalyst by heat treatment of the treated material, wherein the maximum temperature reached by the treated material is 750 to 1000 ° C. and the temperature of the treated material is 750 ° C. or higher. The temperature is adjusted so as to be 15 to 300 seconds.

  According to the said manufacturing method, the alloying degree of Pt and Ru can be controlled by adjusting the maximum temperature in a heat treatment process to 750-1000 degreeC. Moreover, it can fully suppress that Pt particle | grains, Ru particle | grains, and these alloy particle | grains aggregate and become large by restrict | limiting time for the temperature of a to-be-processed object to 750 degreeC or more to 15 to 300 second. Thereby, high dispersibility of the metal particles can be achieved. In the present invention, it is presumed that the high dispersibility of the metal particles contributes to excellent CO resistance.

The heat treatment step preferably includes at least one of the following (1) heating step, (2) maximum temperature holding step, and (3) cooling step from the viewpoint of realizing superior CO resistance. It is more preferable to perform a heat treatment of the workpiece by appropriately combining these steps.
(1) A step of raising the temperature at a heating rate of 30 to 90 ° C./min.
(2) A step of maintaining the temperature of the object to be processed at the maximum temperature for a certain period of time.
(3) A step of lowering the temperature at a cooling rate of 5 to 80 ° C / min.
The (2) maximum temperature holding step is preferably less than 60 seconds. By setting this time to less than 60 seconds, the small particle diameter of the metal particles can be maintained, and even higher CO resistance can be achieved.

  The PtRu / C catalyst according to the present invention includes a support made of a carbon material and platinum and ruthenium supported on the support, and when the methanol oxidation characteristics of the catalyst are measured by an infrared absorption method, The infrared spectrum measured at a potential of 0.2 V has an absorption peak indicating the generation of carbon dioxide.

  According to the PtRu / C catalyst, excellent CO resistance can be achieved as compared with the conventional PtRu / C catalyst. This is presumably due to the excellent oxidation performance of the catalyst. That is, the PtRu / C catalyst according to the present invention generates methanol as well as carbon monoxide from methanol at a potential of 0.2 V when measuring methanol oxidation characteristics by an infrared absorption method. On the other hand, even if the conventional PtRu / C catalyst can oxidize methanol to carbon monoxide at a potential of 0.2 V, there is no catalyst that can oxidize to carbon dioxide.

  According to the present invention, it is possible to produce a PtRu / C catalyst having superior CO resistance as compared with a conventional PtRu / C catalyst. This PtRu / C catalyst is useful as an anode catalyst for a polymer electrolyte fuel cell.

It is a figure which shows the structure of the apparatus for measuring the methanol oxidation characteristic of a catalyst. It is a figure which shows the structure of the front-end | tip part of a sample electrode with which the apparatus of FIG. 1 is equipped, and a prism. It is a X-ray diffraction spectrum of the catalyst which concerns on Example 1 and Comparative Examples 2-4. 2 is an X-ray diffraction spectrum of catalysts according to Examples 1 and 2 and Comparative Example 1. FIG. (A), (b) is a STEM image of the catalyst which concerns on Example 1, (c) is a graph which shows distribution of the metal particle diameter. (A), (b) is a STEM image of the catalyst which concerns on the comparative example 1, (c) is a graph which shows distribution of the metal particle diameter. 3 is an infrared spectrum showing methanol oxidation characteristics of the catalyst according to Example 3. It is an infrared spectrum which shows the methanol oxidation characteristic of a commercial catalyst. It is an infrared spectrum which shows the methanol oxidation characteristic (voltage 0.2V) of the catalyst which concerns on Example 3, and a commercially available catalyst. It is a graph which shows the IV characteristic of a fuel cell at the time of using pure hydrogen as a fuel. It is a graph which shows the IV characteristic of a fuel cell at the time of using hydrogen containing carbon monoxide as a fuel.

<Method for producing PtRu / C catalyst>
The method for producing a PtRu / C catalyst according to the present embodiment includes a Ru supporting step of further supporting ruthenium on a platinum catalyst (Pt / C catalyst) in which platinum is supported on a support made of a carbon material, and in the presence of hydrogen gas. A heat treatment step of obtaining a PtRu / C catalyst by heat-treating an object to be treated obtained through the Ru loading step.

  The Ru supporting step is a step of further supporting ruthenium on the Pt / C catalyst. The Pt / C catalyst can be obtained, for example, by adding and mixing carbon fine particles to an aqueous platinum compound solution and reducing the platinum compound using a reducing agent such as alcohol. A commercially available Pt / C catalyst may be purchased and used as it is.

  As the platinum compound aqueous solution, for example, dinitrodiamine platinum nitric acid aqueous solution or chloroplatinic acid aqueous solution can be used. As the carrier, for example, carbon black can be used. In the Pt / C catalyst, the amount of Pt supported based on the mass of the carrier is preferably 20 to 60% by mass, more preferably 30 to 50% by mass. What is necessary is just to adjust the density | concentration of platinum compound aqueous solution so that it may become the above-mentioned preferable Pt carrying amount.

The Pt / C catalyst is added to the ruthenium compound aqueous solution and mixed, and the ruthenium compound is supported on the Pt / C catalyst by reducing the ruthenium compound using a reducing agent such as alcohol. As the ruthenium compound aqueous solution, for example, an aqueous solution of ruthenium chloride such as ruthenium chloride (RuCl ₃ ), ruthenium nitrate, or ruthenium complex can be used. As the reducing agent, alcohol is preferable, and methyl alcohol, ethyl alcohol, propyl alcohol, and the like can be used.

  The concentration of the ruthenium compound aqueous solution can be adjusted according to the molar ratio of supported Pt and Ru. When the supported amount of Pt is A mole and the supported amount of Ru is B mole, the molar ratio (A / B) of the supported amounts of Pt and Ru is preferably 2/10 to 10/10, and 3/10 to 8/10. Is more preferable, and 5/10 to 7/10 is more preferable.

  The heat treatment step is a step of obtaining a PtRu / C catalyst by heat-treating an object to be processed obtained through the Ru supporting step described above in the presence of hydrogen gas. The heat treatment step can be performed using a heating furnace capable of replacing the air in the furnace with another gas, and is preferably performed in a mixed gas atmosphere of an inert gas such as argon and hydrogen gas. The concentration of hydrogen gas may be about 3 to 20% by volume. By performing the heat treatment in the presence of hydrogen gas, oxidation of Pt and Ru can be suppressed.

  In the heat treatment step, the temperature in the heating furnace is adjusted so that the maximum temperature reached by the workpiece is 750 to 1000 ° C. By adjusting the maximum temperature in the heat treatment step to 750 to 1000 ° C., the degree of alloying of Pt and Ru can be controlled. When the maximum temperature is less than 750 ° C., alloying of Pt and Ru becomes insufficient. On the other hand, when the maximum temperature exceeds 1000 ° C., Pt particles, Ru particles and their alloy particles (hereinafter simply referred to as “metal particles”) are aggregated to increase the particle size, resulting in insufficient catalytic activity. The maximum temperature reached by the workpiece is preferably 800 to 950 ° C, more preferably 850 to 920 ° C, and further preferably 880 to 910 ° C.

  In the heat treatment step, the temperature condition in the heating furnace is set so that the time during which the workpiece is heated at a temperature of 750 ° C. or higher is 15 to 300 seconds. By limiting the time during which the temperature of the object to be processed is 750 ° C. or higher, it is possible to sufficiently suppress the metal particles from aggregating and becoming large, and it is possible to obtain a catalyst in which the metal particles are highly dispersed. When the heat treatment time at 750 ° C. or higher is less than 15 seconds, alloying of Pt and Ru becomes insufficient. On the other hand, if this time exceeds 300 seconds, the metal particles are aggregated to increase the particle size, resulting in insufficient catalytic activity. The time during which the workpiece is heated at a temperature of 750 ° C. or higher is preferably 15 to 120 seconds, more preferably 15 to 60 seconds, and most preferably 20 to 40 seconds.

  The heat treatment step preferably includes at least one of the following (1) heating step, (2) maximum temperature holding step, and (3) cooling step from the viewpoint of realizing superior CO resistance. It is more preferable to perform a heat treatment of the workpiece by appropriately combining these steps.

(1) Heating step Heating from room temperature to the maximum temperature is preferably rapid heating, and the heat treatment step preferably includes a step of heating at a heating rate of 30 to 90 ° C / min. By providing such a temperature raising step, it is possible to more reliably suppress the aggregation of the metal particles and the increase in the particle size. When the heating rate is less than 30 ° C./min, aggregation of metal particles tends to occur. On the other hand, when the heating rate exceeds 90 ° C./min, the temperature in the furnace tends to be non-uniform. The heating rate is more preferably 45 to 90 ° C./min, still more preferably 60 to 90 ° C./min, and most preferably 75 to 90 ° C./min.

(2) Maximum temperature holding step The heat treatment step may include a step of holding the temperature of the object to be processed at the maximum temperature for a certain period of time. The holding time is preferably less than 60 seconds, more preferably less than 40 seconds, and even more preferably less than 20 seconds. By setting this time to less than 60 seconds, the small particle diameter of the metal particles can be maintained, and even higher CO resistance can be achieved. Note that the temperature raising step may be shifted to the temperature lowering step at the same time when the set temperature of the heating furnace reaches the maximum temperature. By shortening the time during which the object to be treated is heat-treated at the maximum temperature in this way, aggregation of metal particles on the carrier is suppressed and high dispersibility can be maintained. Thereby, the PtRu / C catalyst which has the outstanding carbon monoxide tolerance can be obtained.

(3) Temperature drop step Cooling from the maximum temperature to room temperature is preferably rapid cooling, and the heat treatment step preferably includes a step of cooling at a cooling rate of 5 to 80 ° C / min. By providing such a temperature lowering step, it is possible to more reliably suppress the metal particles from agglomerating and increasing the particle size. When the temperature lowering rate is less than 5 ° C./min, aggregation of metal particles tends to occur. On the other hand, if the temperature lowering rate exceeds 80 ° C./min, the heating furnace may be damaged. The temperature lowering rate is more preferably 10 to 80 ° C./min, further preferably 15 to 80 ° C./min, and most preferably 20 to 80 ° C./min.

<PtRu / C catalyst>
When the methanol oxidation characteristic of the PtRu / C catalyst prepared by the above production method was evaluated by an infrared absorption method (IR), it was found that the catalyst had an excellent oxidation ability as compared with the conventional PtRu / C catalyst. found. That is, when a sample electrode coated with a sample thin film containing a PtRu / C catalyst is placed in a HClO ₄ (0.1 mol / L) + methanol (0.5 mol / L) aqueous solution and a potential is applied to the reference electrode, Methanol is oxidized to generate carbon dioxide and the like. The absorption spectrum is measured by irradiating the carbon dioxide or the like with infrared rays. As a spectroscopic device used for the infrared absorption method, a Fourier transform infrared spectroscopic (FTIR) device can be used. The methanol oxidation characteristic referred to in the present invention means that measured by a system in which an apparatus having the configuration shown in FIG. 1 is incorporated in a sample measurement chamber of an FTIR apparatus.

The apparatus of FIG. 1 includes a sample electrode 1 made of gold, a cell 4 in which a reference electrode 2 and a counter electrode 3 are inserted, and a prism 5 made of CaF ₂ . The cell 4 is formed with a gas introduction pipe 7 and an exhaust pipe 8, in which a liquid (HClO ₄ (0.1 mol / L) + methanol (0.5 mol / L) aqueous solution) 9 can be accommodated. . The measuring device includes three gold flat mirrors 12a, 12b, 12c and one gold spherical mirror 11 (R = 100 mm). Infrared light 20 is emitted from a light source (not shown), reflected at the tip of the sample electrode 1, and repeatedly reflected on the surfaces of the gold flat mirrors 12a, 12b, 12c and the gold spherical mirror 11 (not shown). ). The measurement is performed in a state where the chamber of the FTIR apparatus is filled with N ₂ gas.

FIG. 2 is a view showing the tip of the sample electrode 1. A sample thin film 6 having a thickness of several μm is disposed between the tip of the sample electrode 1 and the bottom surface of the prism 5. The sample thin film 6 is formed as follows. That is, a PtRu / C catalyst is added to a solution obtained by adding a small amount of Nafion to ethanol, and this solution is dropped on the upper surface of the sample electrode 1 using a syringe and then dried for about 1 hour. After drying, the sample thin film 6 is formed by pressing the prism 5 with the liquid in the cell (HClO ₄ (0.1 mol / L) + methanol (0.5 mol / L) aqueous solution) interposed therebetween.

Infrared light 20 is incident at an angle of 60 ° with respect to the normal line of the upper surface of the sample electrode 1. A part of the infrared light 20 is absorbed by carbon dioxide, carbon monoxide or the like generated by the oxidizing ability of the catalyst contained in the sample thin film 6. The target substance can be specified by an absorption spectrum having the wave number of infrared light on the horizontal axis and the absorbance on the vertical axis. Peak appearing in the range of wave numbers 2300～2400Cm ^-1 is intended to indicate that the generated carbon dioxide from methanol, the peak appearing in the range of wave numbers 2000～2100Cm ^-1 is an indication that the generated carbon monoxide from methanol (See FIGS. 7 to 9).

  The particle size of the metal particles supported on the PtRu / C catalyst can be measured with a scanning transmission electron microscope (STEM). As the particle size is smaller, the metal particles are highly dispersed on the support, so that the catalytic activity can be improved. In the PtRu / C catalyst according to the present embodiment, the particle size of the metal particles is preferably 2 to 6 nm, more preferably 2 to 5 nm, and further preferably 2 to 4 nm (see FIG. 5).

  According to the manufacturing method according to the above embodiment, it is possible to manufacture a PtRu / C catalyst in which metal particles are highly dispersed as compared with a conventional PtRu / C catalyst. Since this PtRu / C catalyst has excellent CO resistance, it is useful as an anode catalyst for polymer electrolyte fuel cells.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

Example 1
In order to produce the PtRu / C catalyst according to the present invention, first, 1.25 g of a commercially available Pt / C catalyst (Pt loading 40 mass%), 2 g of RuCl ₃ · nH ₂ O, 50 cc of methanol and 200 cc of water were prepared. . These were mixed, held at 80 to 90 ° C. for 8 hours, refluxed, and Ru was supported on the Pt / C catalyst, washed and dried (Ru supporting step). In this example, the ratio (molar ratio) of Pt and Ru was adjusted to 1: 3.

  The object to be processed obtained in the Ru loading step was placed in a room temperature environment in which a mixed gas of hydrogen and argon (hydrogen concentration: 5% by volume) flows at a flow rate of 60 SCCM (cc / min) for 1 hour. Thereafter, the object to be treated was placed in a 100V tubular furnace, and AC100V was raised to 120V with a slidac (variable voltage device). The 100V tubular furnace was rapidly heated from room temperature to 900 ° C. in 14 minutes by applying 120V. When the temperature reaches 900 ° C, the tubular furnace is turned off, the temperature is lowered to 500 ° C in about 18 minutes, the lid of the tubular furnace is opened at 500 ° C, and the temperature is lowered from 500 ° C to 40 ° C in about 1 hour. (Heat treatment process). In this way, a PtRu / C catalyst was obtained.

(Example 2)
A PtRu / C catalyst was obtained in the same manner as in Example 1 except that the time for raising the temperature from room temperature to 900 ° C. was 30 minutes instead of 14 minutes.

(Example 3)
Instead of using 2 g of RuCl ₃ .nH ₂ O, 1 g was used and the Pt and Ru ratio (molar ratio) was adjusted to be 2: 3. C catalyst was obtained.

(Comparative Example 1)
A PtRu / C catalyst was obtained in the same manner as in Example 1 except that rapid heating and rapid cooling were not performed. That is, in this comparative example, the object to be processed obtained through the Ru loading process was heated to 900 ° C. over 9 hours and maintained at 900 ° C. for 1 hour, and then the power was turned off and the furnace cover was not opened for about 5 hours. And cooled naturally.

(Comparative Example 2)
In the heat treatment step, a PtRu / C catalyst was obtained in the same manner as in Example 1 except that the maximum temperature was set to 450 ° C. instead of 900 ° C.

(Comparative Example 3)
In the heat treatment step, a PtRu / C catalyst was obtained in the same manner as in Example 1 except that the maximum temperature was set to 250 ° C. instead of 900 ° C.

(Comparative Example 4)
In the heat treatment step, a PtRu / C catalyst was obtained in the same manner as in Example 1 except that the maximum temperature was set to 25 ° C. instead of 900 ° C.

(Comparative Example 5)
A commercially available PtRu / C catalyst (Pt: Ru = 2: 3 (molar ratio)), which is considered to have the highest CO resistance at the present time, was prepared.

<Analysis by XRD>
The relationship between the maximum temperature and the degree of alloying in the heat treatment process was evaluated by X-ray diffraction (XRD). FIG. 3 shows X-ray diffraction spectra of the PtRu / C catalyst prepared in Example 1 (maximum temperature 900 ° C.) and Comparative Examples 2 to 4 (maximum temperatures: 450 ° C., 250 ° C., 25 ° C.). As shown in FIG. 3, the higher the maximum temperature in the heat treatment step, the higher the peak position shifts and the alloying proceeds. That is, it is possible to control the degree of alloying by adjusting the maximum temperature of the heat treatment process.

  Further, the effect of rapid heating / cooling in the heat treatment process on the particle size of the metal particles was evaluated by XRD. The X-ray diffraction spectra of the PtRu / C catalysts prepared in Examples 1 and 2 and Comparative Example 1 are shown in FIG. As shown in FIG. 4, the shorter the heating / cooling time, the broader the peak, indicating that the particle size of the metal particles is small. That is, the particle size of the metal particles can be controlled by adjusting the temperature increase / decrease rate. Note that the degree of alloying did not change much even when the temperature increase / decrease rate was changed.

<Analysis by STEM>
The result of having evaluated the particle size of the metal particle of the PtRu / C catalyst prepared in Example 1 and Comparative Example 1 by STEM is shown in FIGS. 5 and 6, respectively. As shown in FIG. 5, the PtRu / C catalyst of Example 1 that was heat-treated at a high temperature for a short time had an average particle size as small as 3.42 nm, and fine metal particles were highly dispersed on the carbon support. On the other hand, the PtRu / C catalyst of Comparative Example 1 has a large average particle size of 9.55 nm (see FIG. 6).

<Evaluation of methanol oxidation characteristics by IR analysis>
IR analysis results of methanol oxidation characteristics of the PtRu / C catalyst prepared in Example 3 and the commercially available PtRu / C catalyst of Comparative Example 5 are shown in FIGS. 7 and 8, respectively. As shown in FIG. 7, the PtRu / C catalyst according to Example 3 has an absorption peak between 2300 and 2400 cm ⁻¹ when the potential is 0.2 V, and therefore methanol even at a potential of 0.2 V. It was confirmed that it has an oxidizing ability to oxidize and produce CO ₂ .

On the other hand, as shown in FIG. 8, the commercially available PtRu / C catalyst has no absorption peak between 2300 and 2400 cm ⁻¹ when the potential is 0.2 V, and from the methanol at a potential of 0.2 V. It does not have the ability to oxidize until CO ₂ is produced. FIG. 9 shows a spectrum of methanol oxidation characteristics of the catalyst prepared in Example 3 and a commercially available catalyst at a voltage of 0.2 V for easy comparison. As shown in FIG. 9, these two catalysts are clearly different in terms of methanol oxidation ability.

<CO resistance evaluation>
In order to evaluate the CO resistance of the PtRu / C catalyst according to the present invention, a polymer electrolyte fuel cell was manufactured using the catalysts prepared in Examples and Comparative Examples as anode catalysts. Specifically, four types of fuel cells were assembled using the catalysts of Examples 1 and 3 and Comparative Examples 1 and 5, respectively.

(Operation test 1)
The fuel cells were operated by supplying pure hydrogen not containing CO to the fuel electrodes of the four types of fuel cells. The IV characteristics of each fuel cell are shown in FIG. As shown in FIG. 10, the IV characteristics when the fuel cell was operated using pure hydrogen as a fuel were not significantly different between the catalysts of Examples 1 and 3 and Comparative Examples 1 and 5.

(Operation test 2)
Hydrogen containing CO (CO concentration 2040 ppm) was supplied to the fuel electrodes of the four types of fuel cells, respectively, to operate the fuel cells. The IV characteristics of each fuel cell are shown in FIG. As shown in FIG. 11, the fuel cells using the catalysts of Examples 1 and 3 have a higher voltage than the catalysts of Comparative Examples 1 and 5, although a decrease in voltage is recognized as compared with the case where pure hydrogen is supplied. It was confirmed that the obtained CO resistance was excellent.

<Evaluation of voltage drop due to CO>
Based on the case of using pure hydrogen as a fuel, it was evaluated how much the voltage drops due to carbon monoxide contained in the hydrogen fuel. Table 1 shows the measurement results of voltage at a current density of 0.2 A / cm ² for fuel cells using the catalysts of Examples 1 and 3 and Comparative Examples 1 and 5 as anode catalysts.

  As shown in Table 1, in the fuel cells using the catalysts of Examples 1 and 3, even when hydrogen fuel containing CO at a high concentration of 2040 ppm was used, the voltage was higher than that of the catalysts of Comparative Examples 1 and 5. Has a small drop and excellent CO resistance.

1 ... sample electrode, 2 ... reference electrode, 3 ... counter electrode, 4 ... cell, 5 ... prism, 6 ... sample film, 7 ... gas inlet, 8 ... exhaust pipe, 9 ... Liquid _(HClO 4 (0.1 mol / L) + methanol (0.5 mol / L) aqueous solution), 11 ... gold spherical mirror, 12a to 12c ... gold flat mirror, 20 ... infrared light

Claims (5)

A Ru supporting step of further supporting ruthenium on a platinum catalyst in which platinum is supported on a carrier made of a carbon material;
A heat treatment step of obtaining a PtRu / C catalyst by heat-treating the workpiece obtained through the Ru loading step in the presence of hydrogen gas;
In the heat treatment step, adjusting the temperature so that the maximum temperature reached by the object to be processed is 750 to 1000 ° C. and the time for which the temperature of the object to be processed is 750 ° C. or more is 15 to 300 seconds. A method for producing a characteristic PtRu / C catalyst.   The manufacturing method according to claim 1, wherein the heat treatment step includes a step of increasing the temperature at a heating rate of 30 to 90 ° C./min.   The manufacturing method according to claim 1 or 2, wherein, in the heat treatment step, the time for maintaining the maximum temperature is less than 60 seconds.   The said heat treatment process has a step which falls at a cooling rate of 5-80 degree-C / min, The manufacturing method as described in any one of Claims 1-3 characterized by the above-mentioned. A PtRu / C catalyst comprising a support made of a carbon material and platinum and ruthenium supported on the support,
A PtRu / C catalyst characterized in that when the methanol oxidation characteristics of the catalyst are measured by an infrared absorption method, the infrared spectrum measured at a potential of 0.2 V has an absorption peak indicating the generation of carbon dioxide.