JPH05217586A - Fuel cell and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a fuel cell containing a catalyst excellent in activity and stability and also obtain manufacture thereof. CONSTITUTION:A fuel battery is constituted of an electrode catalytic layer 5 formed on an electrode basic member 1, and the electrode catalytic layer 5 is formed by bonding a catalyst 3A carrying the four-element alloy 2A consisting of Pt, Mo, Ni, and Fe on a carbon carrier. A fuel cell is manufactured through the process for precipitating molybdenum hydroxide, nickel hydroxide, and ferrous hydroxide on the carbon carried by platinum, process for preparing the catalyst by heat-processing the carbon on which the hydroxides are precipitated, at a temperature of 1,000-1,200 deg.C, and a process for preparing an electrode catalytic layer by binding the catalyst by a binder and for laminating the obtained electrode catalytic layer on the electrode basic member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode catalyst layer for a fuel cell and a method for producing the same, and more particularly to a catalyst and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a gas diffusion electrode for a fuel cell has a porous carbon electrode substrate having excellent electric conductivity, and an electrode catalyst layer obtained by binding a catalyst powder carrying a noble metal with polytetrafluoroethylene is laminated on the carbon electrode substrate. Formed.

Oxygen or hydrogen, which is the reaction gas supplied in the electrode catalyst layer, and the phosphoric acid electrolyte and the catalyst coexist three-phase uniformly, so that the electrochemical reaction can be directly taken out as electric energy.

FIG. 1 is a sectional view showing an electrode structure of a conventional fuel cell. The fuel cell is an electrode catalyst in which an electrode base material 1 made of porous carbon having air or hydrogen flow passages and a catalyst 3 carrying platinum 2 are mixed with polytetrafluoroethylene PTFE 4 which imparts appropriate water repellency. It consists of layer 5. In this electrode catalyst layer, the supplied reaction gases, air and hydrogen, and the electrolyte, phosphoric acid, cause a three-phase coexistence state on the surface of the catalyst particles, whereby an electrochemical reaction occurs and electrical energy can be directly extracted. ..

Conventionally, as a catalyst for a phosphoric acid fuel cell, a catalyst using platinum, which has corrosion resistance to high temperature phosphoric acid, has been used. Since the catalyst plays an extremely important role in the electrode reaction, it is necessary to enhance the activity and stability of the catalyst in order to improve the output and life of the battery.

As a conventional method for producing a platinum catalyst, a liquid phase reduction method is generally used. Specifically, in order to facilitate dispersion of carbon black supporting platinum in a liquid phase, an acid treatment such as nitric acid or glacial acetic acid is performed, and then platinum necessary for supporting an aqueous chloroplatinic acid solution is added, After adjusting the liquid temperature to 40 to 90 ° C, hydrazine and formic acid are added dropwise as a reducing agent to reduce platinum.

Further, in order to increase the activity of the catalyst, alloying is carried out by adding a second metal component such as vanadium, chromium, cobalt, nickel or iron to the catalyst carrying platinum. First, the catalyst obtained by reducing platinum described above is dispersed again in an aqueous solution, the nitrate of the second metal is added, and the second metal is converted to hydroxide on the carbon surface with an alkali agent such as potassium hydroxide, sodium hydroxide or aqueous ammonia. Deposit. This was filtered, washed with water, dried, and then heat-treated at 800–1000 ° C in an inert atmosphere to produce alloy catalysts. It is a well-known technique that an alloy catalyst obtained by adding another IV to VIII group transition metal to a platinum catalyst can improve the catalytic activity, and platinum-chromium-cobalt is further sought in order to improve the activity and stability. (JP-A-59-141169), platinum-iron-cobalt (JP-A-62-163746), platinum-nickel-cobalt (
Three-way catalysts such as JP-A-63-190254) are also introduced.

[0008]

However, although these catalysts are excellent in initial activity, they show deterioration in characteristics in a relatively short time, so that it is necessary to improve stability. The present invention has been made in view of the above points, and an object thereof is to provide a fuel cell having excellent characteristics and stability by developing a novel catalyst substance and a method for producing the same.

[0009]

According to the first aspect of the present invention, there is provided an electrode catalyst layer on an electrode substrate, the electrode catalyst layer comprising platinum, molybdenum and nickel on a carbon support.
What is formed by binding a catalyst supporting an iron quaternary alloy with a binder, according to the second invention, has a first step, a second step, and a third step, and the first step Is platinum supported carbon on molybdenum hydroxide, nickel hydroxide,
The second step is the step of depositing iron hydroxide, and the second step is to remove the hydroxide-deposited carbon at a temperature of 1000 to 1200.
It is a step of preparing a catalyst by heat treatment at ℃, the third step is a step of binding the catalyst with a binder to prepare an electrode catalyst layer and laminating the obtained electrode catalyst layer on an electrode substrate. According to the third aspect of the invention, the electrode catalyst layer is provided on the electrode base material, and the electrode catalyst layer comprises a catalyst supporting platinum, molybdenum, nickel, and a quaternary alloy of cobalt with a binder. Being formed by binding, according to the fourth invention, a first step, a second step, and a third step, the first step is carbon supported platinum, molybdenum hydroxide, A step of depositing nickel hydroxide and cobalt hydroxide, a second step is a step of heat-treating the hydroxide-deposited carbon at a temperature of 1000 to 1200 ° C. to prepare a catalyst, and a third step is the above The catalyst is bound with a binder and charged. It is a step of preparing a catalyst layer and laminating the obtained electrode catalyst layer on an electrode substrate. According to the fifth invention, the electrode catalyst layer is provided on the electrode substrate, and the electrode catalyst layer is a carbon carrier. Platinum, molybdenum, titanium, and the one that is formed by binding a catalyst supporting a quaternary alloy of cobalt with a binder, according to the sixth invention, a first step, a second step, There is a third step, the first step is a step of depositing molybdenum hydroxide, titanium hydroxide and cobalt hydroxide on the platinum-supported carbon, and the second step is the deposition of the hydroxide. Carbon temperature 900
To 1100 ° C. to prepare a catalyst by heat treatment, and the third step is a step of binding the catalyst with a binder to prepare an electrode catalyst layer and laminating the obtained electrode catalyst layer on an electrode base material. Is achieved.

[0010]

[Function] A binary-type catalyst having relatively high initial activity and excellent stability, combining molybdenum, nickel and iron with platinum having excellent catalytic activity to form a platinum-molybdenum-nickel-iron quaternary alloy catalyst. Thus, a catalyst having excellent catalytic activity and stability can be obtained. It is a binary catalyst with relatively high initial activity and excellent stability. By combining platinum, which has excellent catalytic activity, with molybdenum, nickel, and cobalt to form a platinum-molybdenum-nickel-cobalt quaternary alloy catalyst, It is possible to obtain a catalyst having excellent activity and stability. It is a binary catalyst with relatively high initial activity and excellent stability, and molybdenum, titanium, and cobalt are combined with platinum with excellent catalytic activity to form a platinum-molybdenum-titanium-cobalt quaternary alloy catalyst. It is possible to obtain a catalyst having excellent activity and stability.

[0011]

EXAMPLES The present invention will be described based on examples. Embodiment 1 FIG. 2 is a sectional view showing a fuel cell according to an embodiment of the first invention. The quaternary alloy 2A is used in place of the conventional platinum 2. Such an electrode structure is prepared as follows. Weigh 9g of carbon black such as acetylene black and add to 200ml of pure water. Next, 1 g of chloroplatinic acid aqueous solution was added as platinum (pt) and the temperature was raised to 60 ° C. After the temperature becomes constant, the pH is adjusted to 10 with NaOH 2N solution and 3% hydrazine solution is added dropwise to reduce chloroplatinic acid. After completion of the reduction, a platinum-supported catalyst can be obtained by filtering / washing with a glass filter and drying. The platinum crystallite diameter of this platinum-supported catalyst was 28Å.

The alloying of the platinum-supported catalyst thus obtained is shown below. First, the platinum-supported catalyst is dispersed in 200 ml of pure water. Separately, 0.3 g of molybdenum pentachloride as molybdenum, 0.3 g of iron nitrate as iron (Fe) and 0.30 g of nickel nitrate as nickel are weighed and dissolved in ethanol. Ammonia water was added to this solution to adjust the pH to 8
And prepare an intimate mixture of molybdenum, nickel, and iron that has become hydroxide using an ultrasonic disperser. This solution is added to the solution in which the platinum-supported catalyst is dispersed, ammonia water is added dropwise to adjust the pH to 11, and the solution is sufficiently contacted for 1 to 3 hours. Then, it is filtered with a glass filter, washed with water, dried, and then heat-treated at 1000 to 1200 ° C in a nitrogen stream. The crystallized diameter of the alloyed catalyst thus obtained was 31Å.

The obtained platinum-molybdenum-nickel-iron quaternary alloy catalyst was able to obtain excellent properties in both initial activity and stability as compared with conventional alloy catalysts. table 1
Shows the initial characteristics and the change in crystallite size after 1000 hours. The obtained quaternary alloy catalyst is applied on the electrode base material 1 together with the binder polytetrafluoroethylene PTFE 4 and baked.

[0014]

[Table 1]

Example 2 9 g of carbon black such as acetylene black was weighed,
Add to 200 ml of pure water. Next, 1 g of chloroplatinic acid aqueous solution was added as platinum (pt) and the temperature was raised to 60 ° C. After the temperature becomes constant, the pH is adjusted to 10 with NaOH 2N solution and 3% hydrazine solution is added dropwise to reduce chloroplatinic acid. After completion of the reduction, a platinum-supported catalyst can be obtained by filtering / washing with a glass filter and drying. The platinum crystallite diameter of this platinum-supported catalyst is 28.
It was Å.

The alloying of the platinum-supported catalyst thus obtained is shown below. First, the platinum-supported catalyst is dispersed in 200 ml of pure water. Separately, 0.3 g of molybdenum pentachloride as molybdenum, 0.3 g of cobalt nitrate as cobalt (Co) and 0.30 g of nickel nitrate as nickel are weighed and dissolved in methanol. Furthermore, a potassium hydroxide solution is added to this solution to adjust the pH to 8, and an ultrasonic disperser is used to prepare a homogeneous mixed solution of molybdenum, nickel, and cobalt that has become hydroxide. This solution is added to the solution in which the platinum-supported catalyst is dispersed, a potassium hydroxide solution is added dropwise to adjust the pH to 11, and the solution is sufficiently contacted for 1 to 3 hours. Then, it is filtered with a glass filter, washed with water, dried and then 1000 to 12 in a nitrogen stream.
Heat treatment at 00 ° C. The crystallized diameter of the alloyed catalyst thus obtained was 30Å.

The obtained platinum-molybdenum-nickel-molybdenum quaternary alloy catalyst was able to obtain excellent properties in both initial activity and stability as compared with conventional alloy catalysts. Table 1 shows the initial characteristics and the change in crystallite size after 1000 hours.

Example 3 9 g of carbon black such as acetylene black was weighed,
Add to 200 ml of pure water. Next, 1 g of chloroplatinic acid aqueous solution was added as platinum (pt) and the temperature was raised to 60 ° C. After the temperature becomes constant, the pH is adjusted to 10 with NaOH 2N solution and 3% hydrazine solution is added dropwise to reduce chloroplatinic acid. After completion of the reduction, a platinum-supported catalyst can be obtained by filtering / washing with a glass filter and drying. The platinum crystallite diameter of this platinum-supported catalyst is 28.
It was Å.

The alloying of the platinum-supported catalyst thus obtained is shown below. First, the platinum-supported catalyst is dispersed in 200 ml of pure water. Separately, 0.3 g of molybdenum pentachloride as molybdenum, 0.3 g of cobalt nitrate as cobalt (Co) and 0.30 g of titanium trichloride as titanium are weighed and dissolved in hot water. Ammonia water is added to this solution.
Adjust the pH to 8 and use an ultrasonic disperser to prepare a homogeneous mixture of molybdenum, titanium, and cobalt that has become hydroxide. This solution is added to the solution in which the platinum-supported catalyst is dispersed, ammonia water is added dropwise to adjust the pH to 11, and the solution is sufficiently contacted for 1 to 3 hours. Then, it is filtered with a glass filter, washed with water, dried and then heat-treated at 900-1100 ° C in a nitrogen stream.
The crystallized diameter of the alloyed catalyst thus obtained was 32Å.

The obtained platinum-molybdenum-titanium-cobalt quaternary alloy catalyst was able to obtain excellent properties in both initial activity and stability as compared with conventional alloy catalysts.
Table 1 shows the initial characteristics and the change in crystallite size after 1000 hours.

[0021]

According to the first invention, an electrode catalyst layer is provided on an electrode substrate, and the electrode catalyst layer is a catalyst in which a quaternary alloy of platinum, molybdenum, nickel and iron is supported on a carbon carrier. According to the second invention, the first step, the second step, and the third step,
The first step is a step of depositing molybdenum hydroxide, nickel hydroxide, and iron hydroxide on the platinum-supported carbon, and the second step is to deposit the hydroxide-deposited carbon at a temperature of 1000 to 1200 ° C. It is a step of preparing a catalyst by heat treatment, the third step is a step of binding the catalyst with a binder to prepare an electrode catalyst layer and laminating the obtained electrode catalyst layer on an electrode base material, According to the third invention, the electrode catalyst layer is provided on the electrode base material, and the electrode catalyst layer binds the catalyst supporting platinum, molybdenum, nickel and cobalt quaternary alloy on the carbon support with the binder. According to the fourth invention, it has a first step, a second step, and a third step, and the first step is molybdenum hydroxide on carbon on which platinum is supported, and hydroxide. Nickel and cobalt hydroxide A step of depositing, the second step is a step of preparing a catalyst was heat-treated at 1200 ° C. to not temperature 1000 carbon deposited in the hydroxide,
The third step is a step of binding the catalyst with a binder to prepare an electrode catalyst layer and laminating the obtained electrode catalyst layer on an electrode substrate, according to the fifth invention, on the electrode substrate. The electrode catalyst layer on the carbon carrier, the electrode catalyst layer is formed by binding a catalyst supporting a quaternary alloy of platinum, molybdenum, titanium, and cobalt on a carbon support with a binder. According to the method, it has a first step, a second step, and a third step, and the first step is a step of depositing molybdenum hydroxide, titanium hydroxide, and cobalt hydroxide on platinum-supported carbon. The second step is a step of preparing a catalyst by heat-treating the hydroxide-deposited carbon at a temperature of 900 to 1100 ° C., and the third step is binding the catalyst with a binder to form an electrode catalyst layer. Electrocatalyst layer obtained by preparation Since the step of laminating on the electrode substrate, the change with time on the crystallite diameter is small can be obtained less quaternary alloy catalyst, to obtain a fuel cell having excellent result characteristics and stability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrode structure of a conventional fuel cell.

FIG. 2 is a sectional view showing an electrode structure of a fuel cell according to an embodiment of the first invention.

[Explanation of symbols]

 1 Electrode Base Material 2 Platinum 2A Quaternary Alloy 3 Catalyst 3A Catalyst 4 PTFE 5 Electrode Catalyst Layer

Claims (13)

[Claims] 1. An electrode catalyst layer is provided on an electrode base material, and the electrode catalyst layer comprises platinum and molybdenum on a carbon support.
A fuel cell comprising a catalyst supporting a quaternary alloy of nickel and iron bound with a binder. 2. The fuel cell according to claim 1, wherein the composition of the quaternary alloy is such that molybdenum, nickel and iron are each in the range of 10 to 25 wt%, and the balance is platinum. 3. A first step, a second step, and a third step, wherein the first step deposits molybdenum hydroxide, nickel hydroxide, and iron hydroxide on platinum-supported carbon. The second step is the step of removing the hydroxide-deposited carbon at a temperature of 10
The step is a step of preparing a catalyst by heat treatment at 00 to 1200 ° C. The third step is to bind the catalyst with a binder to prepare an electrode catalyst layer and laminate the obtained electrode catalyst layer on an electrode substrate. A method of manufacturing a fuel cell, which is a process. 4. The method according to claim 3, wherein the hydroxide is deposited by adding ammonia water to a mixed ethanol solution of molybdenum pentachloride, nickel nitrate and iron nitrate to adjust the pH to 8 and thereby obtaining a suspension. Is ultrasonically dispersed to prepare a homogeneous mixed solution, and the homogeneous mixed solution is brought into contact with carbon carrying platinum, and further ammonia water is added to adjust the pH to 11. Production method. 5. An electrode catalyst layer is provided on an electrode base material, and the electrode catalyst layer comprises platinum and molybdenum on a carbon carrier.
A fuel cell comprising a catalyst supporting a quaternary alloy of nickel and cobalt bound with a binder. 6. The fuel cell according to claim 5, wherein the composition of the quaternary alloy is such that molybdenum, nickel and cobalt are each in the range of 10 to 25 wt%, and the balance is platinum. 7. A first step, a second step, and a third step, wherein the first step deposits molybdenum hydroxide, nickel hydroxide, and cobalt hydroxide on platinum-carrying carbon. The second step is the step of removing the hydroxide-deposited carbon at a temperature of 10
The step is a step of preparing a catalyst by heat treatment at 00 to 1200 ° C. The third step is to bind the catalyst with a binder to prepare an electrode catalyst layer and laminate the obtained electrode catalyst layer on an electrode substrate. A method of manufacturing a fuel cell, which is a process. 8. The method according to claim 7, wherein the hydroxide is deposited by adding potassium hydroxide solution to a mixed methanol solution of molybdenum pentachloride, nickel nitrate and cobalt nitrate to adjust the pH to 8. The suspension is ultrasonically dispersed to prepare a homogeneous mixture, which is brought into contact with platinum-supported carbon, and a potassium hydroxide solution is further added to adjust the pH to 11. Method for manufacturing a fuel cell. 9. An electrode catalyst layer is provided on an electrode base material, and the electrode catalyst layer comprises platinum and molybdenum on a carbon support.
A fuel cell, comprising a catalyst supporting titanium and a quaternary alloy of cobalt bound by a binder. 10. The fuel cell according to claim 9, wherein the composition of the quaternary alloy is 1 for each of molybdenum, titanium and cobalt.
A fuel cell characterized by being in the range of 0 to 25% by weight, the balance being platinum. 11. A first step, a second step and a third step, wherein the first step deposits molybdenum hydroxide, titanium hydroxide and cobalt hydroxide on platinum-supported carbon. The second step is to remove the hydroxide-deposited carbon at a temperature of 90
It is a step of preparing a catalyst by heat treatment at 0 to 1100 ° C. The third step is to bind the catalyst with a binder to prepare an electrode catalyst layer and to laminate the obtained electrode catalyst layer on an electrode substrate. A method of manufacturing a fuel cell, which is a process. 12. A method according to claim 11, wherein the hydroxide is deposited by dissolving ribden pentachloride, titanium trichloride and cobalt nitrate in hot water and adjusting the pH to 11 with ammonia water.
The method for producing a fuel cell is characterized in that the obtained suspension is ultrasonically dispersed to prepare a homogeneous mixed solution, and the homogeneous mixed solution is brought into contact with platinum-supported carbon. 13. The method for producing a fuel cell according to claim 3, 7, or 11, wherein the heat treatment is performed in a nitrogen stream.