Patent ID: 12244022

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Various distinctive features shown in the following embodiments can be combined with each other. In addition, an invention can be established independently for each of the distinctive features.

1-1. Support and Metal Catalyst100

As shown inFIGS.1to4, the support and metal catalyst100comprises a support powder which is an aggregate of support fine particles150having a chained portion structured by fusion bonding a plurality of crystallites120into a chain, and metal fine particles130being supported on the support powder.

The electric conductivity of the support and metal catalyst100is preferably 0.02 S/cm or more, more preferably 0.03 S/cm or more. The electric conductivity is, for example, 0.02 to 1000 S/cm, and is particularly for example, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 1, 10, 100, or 1000 S/cm, and can be in the range between the two values exemplified herein.

Hereinafter, each of the constituents will be explained.

1-1. Support Fine Particles150and Support Powder

As shown inFIG.1, in the support fine particles150, a three-dimensional void110surrounded by the branch160and pores existing between a plurality of branches is formed. Here, a plurality of crystallites120structuring the support fine particles150is fusion bonded to form a chained portion, thereby forming the branch160. Gas diffusion route to diffuse and transfer oxygen as the oxidant and/or hydrogen as the fuel to the support and metal catalyst100is formed by the three-dimensional arrangement of the support fine particles150described above.

As shown inFIGS.1to3as an example of structure model of the support and metal catalyst, the support fine particles150comprise four pores of a first pore surrounded by points b1, b2, b5, b4, and b1, where the branches link with each other (may be referred to as branching points, or merely as branch); a second pore surrounded by branching points b1, b2, b3, and b1; a third pore surrounded by branching points b2, b3, b6, b7, b5, and b2; and a fourth pore surrounded by branching points b1, b3, b6, b7, b5, b4, and b1. Here, when a plane surrounded by the branching points of each of the pores (first to fourth pores) is taken as the pore plane, the void110is a three-dimensional space surrounded by the four pore planes. The support fine particles150comprise a plurality of pores surrounded by a plurality of branching points in which a plurality of branches link with each other. Further, the three-dimensional spaces (voids) which are surrounded by the plurality of pores are provided sequentially, thereby structuring the support fine particles. Accordingly, the void serves as the gas diffusion route (gas diffusion path) of oxygen, hydrogen and the like.FIG.4shows the gas diffusion route inFIG.1. InFIG.4, one example of the gas diffusion route (gas diffusion path) of void110is shown. Flow (gas diffusion route)170of oxidant (gas), fuel gas and the like can flow in the desired direction via the void110as shown inFIG.4. That is, the void110serves as the gas diffusion route.

Here, as a simple structure of the support fine particles150, the support fine particles can have only one pore (for example, the first pore surrounded by the branching points b1, b2, b5, b4, and b1). In such case, a void110having a thickness of the crystallite grain of the crystallite120is provided. As a simpler structure, the support fine particles150can have one or more branches. In such case, the branches within the support fine particles150prohibits cohesion of the support fine particles, thereby providing void110between the support fine particles.

Here, the “pore” mentioned above can also be mentioned as closed curve (closed loop). Otherwise, it can be said that a void110surrounded by a closed plane including the afore-mentioned plurality of branching points (for example, branching points b1to b7) is provided. As the branching points b1to b7, the center of gravity of the crystallite of the metal oxide structuring the support fine particles150in which the branches connect with each other can be taken as the branching point, or an arbitrary point in the crystallite can be taken as the branching point.

The support fine particles150have a branch160comprising a chained portion which is structured by fusion bonding a plurality of crystallites120into a chain. The branch160itself has a nature to allow electrons to flow. As shown inFIGS.1to4, the support fine particles150have a plurality of branches160, and the branches connect with each other at branching points (b1to b7), by which a network is structured. Electrically conductive nature can be seen among these. Accordingly, the branches160of the support fine particles150shown by the dotted line from point P0inFIG.1itself structures an electron conduction route (electron conduction path)140.

The size of the crystallite120is preferably 1 to 100 nm, more preferably 5 to 40 nm. The size is, particularly for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 50, or 100 nm, and can be in the range between the two values exemplified herein. The size of the crystallite120(crystallite diameter) can be obtained in accordance with a Sheller formula using half-width in the XRD pattern peak.

The aggregate of the support fine particles150is in the form of a powder. Such aggregate is referred to as “support powder”.

The mean particle size of the support fine particles150in the support powder is in the range of 0.1 μm to 4 μm, preferably in the range of 0.5 μm to 2 μm. The mean particle size of the support fine particles150can be measured with a laser diffraction/scattering particle size distribution analyzer.

The specific surface area of the support powder is preferably 12 m2/g or more, and is more preferably 25 m2/g or more. The specific surface area is, for example, 12 to 100 m2/g, particularly for example, 12, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, or 100 m2/g, and can be in the range between the two values exemplified herein.

One example of the distribution of the void110contained in the support powder is shown inFIG.5. The distribution of the void110can be obtained by measuring the volume of the three-dimensional void of the support powder by using a mercury porosimetry. InFIG.5, volume per one void is obtained from the number of voids and the measured volume value, and then a cumulative size distribution is shown as a value of a diameter of a sphere, the sphere being obtained by converting the obtained volume to sphere (sphere equivalent diameter by mercury injection method). As shown inFIG.5, void of 11 nm or smaller (primary pore) and void of larger than 11 nm (secondary pore) preferably exist in the support powder. Accordingly, gas diffusion route is secured.

The support powder preferably has a void fraction of 50% or higher, more preferably 60% or higher. The void fraction is, for example, 50 to 80%, particularly for example, 50, 55, 60, 65, 70, 75, or 80%, and can be in the range between the two values exemplified herein. The void fraction can be obtained as the ratio of the bulk density of the support powder molded with a uniaxial pressure molding machine (molded body size: 5 mm×5 mm×30 mm, molding pressure: 2 MPa or less) to the true density of the support powder, mercury press-in method, or FIB-SEM.

The support powder preferably has a repose angle of 50 degrees or less, and more preferably a repose angle of 45 degrees or less. In such case, the support powder has a similar flowability as flour, and thus handling is simple. The repose angle is, for example, 20 to 50 degrees, particularly for example, 20, 25, 30, 35, 40, 45, or 50, and can be in the range between the two values exemplified herein. The repose angle can be obtained by drop volume method.

The support fine particles150are structured with metal oxide. The metal oxide is doped with dopant element. The dopant element is an element having a different valence than titanium and tin. As the dopant element, at least one is selected among rare earth elements such as yttrium, Group 5 elements such as niobium and tantalum, Group 6 elements such as tungsten, and Group 15 elements such as antimony. When doping is performed with such elements, support fine particles can be imparted with conductivity. Among such elements, Group 5 elements represented by niobium and tantalum, or Group 6 elements represented by tungsten are preferred, and tantalum, niobium, antimony or tungsten are particularly preferred. Tantalum or tungsten are particularly preferred due to their large solid solution capacity.

The atom ratio of the dopant element with respect to the entire metal contained in the metal oxide is preferably 0.05 to 0.30. In such case, the electric conductivity of the support and metal catalyst100becomes particularly high. The atom ratio is, particularly for example, 0.05, 0.10, 0.15, 0.20, 0.25, or 0.30, and can be in the range between the two values exemplified herein.

The metal oxide is preferably a complex oxide of titanium and tin, and the atomic ratio of titanium with respect to the total of titanium and tin is preferably 0.30 to 0.80, more preferably 0.40 to 0.80. In such case, the electric conductivity of the support and metal catalyst100becomes high. The atom ratio is, particularly for example, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, or 0.80, and can be in the range between the two values exemplified herein.

1-2. Metal Fine Particles130

The metal fine particles130are fine particles of metal or metal alloy which can serve as a catalyst. The metal fine particles130preferably contain platinum, and the metal fine particles130are more preferably platinum. The mean particle size of the plurality of metal fine particles130supported on the support powder is 3 to 10 nm. The mean particle size is, particularly for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nm, and can be in the range between the two values exemplified herein. When the mean particle size of the metal fine particles130is smaller than 3 nm, the metal fine particles would dissolve along with the progress of the electrode reaction. On the other hand, when the mean particle size is larger than 10 nm, the electrochemical active area would become small, and thus the desired electrode performance cannot be achieved. The metal fine particles130are, among the particles shown in the transmission image of support and metal catalyst100obtained by TEM inFIG.6, particles that are dispersed on the surface of the crystallites (120) having a crystallite size of 1 to 100 nm and having higher contrast than the crystallites. The size of such metal fine particles can be obtained by measuring the diameter of the circumscribed circle of all of the imaged metal fine particles130, and calculating their arithmetic mean.

The metal fine particles130preferably comprise a core and a skin layer covering the core. The core preferably comprises an alloy of a noble metal and a transition metal. The skin layer preferably comprises a noble metal. As the noble metal, platinum is preferable. As the transition metal, cobalt (Co) or nickel (Ni) are preferable, and cobalt is especially suitable.

Preferably, titanium is contained in the metal fine particles130in a solid solution state. Preferably, titanium is contained as a solid solution more in the core than the skin layer. Accordingly, when titanium is contained as a solid solution more in the core, activity of the core can be improved.

The amount of the metal fine particles130being supported is preferably 1 to 50 mass %, more preferably 5 to 25 mass %. The amount being supported is, particularly for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 mass %, and can be in the range between the two values exemplified herein.

The electrochemical active surface area of the support and metal catalyst100is preferably 20 m2/g or more. This surface area is, for example, 20 to 200 m2/g, and is particularly for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 m2/g, and can be in the range between the two values exemplified herein. The electrochemical active surface area can be obtained by the rotating ring disk electrode method or cyclic voltammetry (sweep rate of 0.1 V/sec. or less) of membrane electrode assembly.

2. Fuel Cell200

A model diagram of the fuel cell according to the present invention is shown inFIG.7. InFIG.7, the fuel cell200is structured by aligning the catalyst layer220A and the gas diffusion layer210A on the anode201side, and the catalyst layer220K and the gas diffusion layer210K on the cathode202side, facing each other with the electrolyte membrane230in between. That is, the gas diffusion layer210A on the anode side, the catalyst layer220A on the anode side, the electrolyte membrane230, the catalyst layer220K on the cathode side, and the gas diffusion layer210K on the cathode side are aligned in this order. By connecting the load203in between the anode201and the cathode202of the fuel cell200, power is output to the load203.

Preferably, at least one of the catalyst layer220A on the anode side and the catalyst layer220K on the cathode side is formed with the support and metal catalyst100. More preferably, the catalyst layer220A on the anode side is formed with the support and metal catalyst100. The electric resistance of the support and metal catalyst100is larger under oxygen atmosphere than under hydrogen atmosphere. Therefore, when the support and metal catalyst100is used for the catalyst layer220A on the anode side, occurrence of oxygen reduction reaction at the catalyst layer220A on the anode side is suppressed when the fuel cell is started or shutdown. Therefore, corrosion reaction of the catalyst layer220K on the cathode side is suppressed even when the support thereof is carbon. Accordingly, degradation of power generation performance of the fuel cell is suppressed.

As the catalyst other than the support and metal catalyst100, catalysts disclosed in Patent Literature 1, catalysts structured by supporting metal fine particles on support of ceramics (for example, tin oxide, titanium oxide) other than the metal oxide of the present invention, and catalysts structured by supporting metal fine particles on carbon support, can be mentioned.

3. Method for Manufacturing Support Powder

First, referring toFIG.8toFIG.11, the manufacturing apparatus1which can be used for the manufacture of the support powder is explained. The manufacturing apparatus1comprises a burner2, a raw material supplying unit3, a reaction cylinder4, a collector5, and a gas reservoir6. The raw material supplying unit3comprises an outer cylinder13, and a raw material distribution cylinder23.

The burner2is a cylinder, and the raw material supplying unit3is arranged in the burner2. Burner gas2ais distributed between the burner2and the outer cylinder13. The burner gas2ais used to form a flame7at the tip of the burner2by ignition. A high temperature region having a temperature of 1000° C. or higher is formed by the flame7. The burner gas2apreferably contains a combustible gas such as propane, methane, acetylene, hydrogen, or nitrous oxide. In one example, a gas mixture of oxygen and propane can be used as the burner gas2a. The temperature of the high temperature region is 1000 to 2000° C. for example, and is particularly for example, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000° C., and can be in the range between the two values exemplified herein.

A raw material solution23afor generating the support powder is distributed in the raw material distribution cylinder23. As the raw material solution23a, the one containing a titanium compound and tin compound is used. As the titanium compound and tin compound, fatty acid titanium and fatty acid tin can be mentioned for example. The number of carbon atoms in the fatty acid is, for example, 2 to 20, preferably 4 to 15, and further preferably 6 to 12. As the fatty acid, octylic acid is preferable.

The raw material solution23acan contain metal compound for doping the support fine particles150. As the metal compound, fatty acid metal (Nb, Ta, W and the like) salt can be mentioned for example. The number of carbon atoms in the fatty acid is, for example, 2 to 20, preferably 4 to 15, and further preferably 6 to 12. As the fatty acid metal salt, niobium octylate, tantalum octylate, antimony octylate, and tungsten octylate are preferable.

In the raw material solution23a, the titanium compound and the tin compound are preferably dissolved or dispersed in a non-aqueous solvent. As the non-aqueous solvent, organic solvent represented by terpen can be mentioned. If moisture is contained in the raw material solution23a, fatty acid titanium and fatty acid tin can undergo hydrolysis and degrade.

Mist gas13aused for converting the raw material solution23ainto a mist is distributed in between the outer cylinder13and the raw material distribution cylinder23. When the mist gas13aand the raw material solution23aare jetted together from the tip of the raw material supplying unit3, the raw material solution23ais converted into a mist. The mist23bof the raw material solution23ais sprayed into the flame7, and the titanium compound and the tin compound in the raw material solution23aundergoes a thermal decomposition reaction in the flame7. Accordingly, support powder which is an aggregate of support fine particles150having a chained portion structured by fusion bonding the crystallite120into a chain is generated. The mist gas13ais oxygen in one example.

The reaction cylinder4is provided between the collector5and the gas reservoir6. The flame7is formed in the reaction cylinder4. The collector5is provided with a filter5aand a gas discharging portion5b. A negative pressure is applied to the gas discharging portion5b. Accordingly, a flow which flows towards the gas discharging portion5bis generated in the collector5and the reaction cylinder4.

The gas reservoir6has a cylinder shape, and comprises a cold gas introducing portion6aand a slit6b. A cold gas6gis introduced from the cold gas introducing portion6ainto the gas reservoir6. The cold gas introducing portion6ais directed in a direction along the tangential line of the inner peripheral wall6cof the gas reservoir6. Therefore, the cold gas6gintroduced through the cold gas introducing portion6ainto the gas reservoir6revolves along the inner peripheral wall6c. At the center of the gas reservoir6, a burner insertion hole6dis provided. The burner2is inserted through the burner insertion hole6d. The slit6bis provided in the vicinity of the burner insertion hole6dso as to surround the burner insertion hole6d. Accordingly, when the burner2is inserted through the burner insertion hole6d, the slit6bis provided so as to surround the burner2. The cold gas6gin the gas reservoir6is driven by the negative pressure applied to the gas discharging portion5b, and is discharged from the slit6btowards the reaction cylinder4. The cold gas6gcan be any gas so long as it can cool the metal oxide generated, and is preferably an inert gas, for example, air. The flow speed of the cold gas6gis preferably two times or more of the flow speed of the burner gas2a. The upper limit of the flow speed of the cold gas6gis not particularly limited, and is 1000 times the flow speed of the burner gas2afor example. The ratio of flow speed of cold gas6g/flow speed of burner gas2ais 2 to 1000 for example, and the ratio is particularly for example, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, 200, 500, or 1000, and can be in the range between the two values exemplified herein. Here, in the present embodiment, a negative pressure is applied to the gas discharging portion5bto allow the cold gas6gto flow, however, a positive pressure can be applied to the gas introducing portion6ato allow the cold gas6gto flow.

After the support fine particles150come out of the flame7, the support fine particles150would be immediately cooled by the cold gas6g, thereby allowing to maintain the structure having the chained portion. The support fine particles150after cooling would be trapped by the filter5aand collected. The trapped support fine particles150can be subjected to heat treatment at 400 to 1000° C. to adjust the crystallite diameter.

In the present invention, the support powder which is an aggregate of the support fine particles150can be manufactured by using the manufacturing apparatus1. Here, a high-temperature region of 1000° C. or higher is formed at the tip of the burner2by the flame7, and the titanium compound and the tin compound are allowed to undergo a thermal decomposition reaction in this high-temperature region while supplying the cold gas6gthrough the slit6bto the surroundings of the high-temperature region. The high-temperature region can be formed by plasma instead of the flame7.

4. Method for Manufacturing Support and Metal Catalyst100

The method for manufacturing support and metal catalyst100comprises a supporting step and a reduction step.

<Supporting Step>

In the supporting step, the metal fine particles130are supported on the support powder. Such supporting can be performed by a reverse micelle method, a colloidal method, an impregnation method and the like. The supporting step of the colloidal method comprises an adsorbing step and a heat treatment step.

In the adsorbing step, the metal colloidal particles are adsorbed onto the support powder. More particularly, the metal colloidal particles synthesized by the colloidal method is dispersed in an aqueous solution to prepare a dispersion, and then the metal colloidal particles are added and mixed in the dispersion. Accordingly, the colloidal particles are adsorbed onto the surface of the support powder. The support powder having the colloidal particles adsorbed thereon is then filtered and dried, thereby being separated from the dispersion medium. The metal of the metal colloidal particles include platinum.

In the heat treatment step, heat treatment is performed at 100 to 400° C. after the adsorbing step to convert the metal colloidal particles into metal fine particles130. The temperature of the heat treatment is, particularly for example, 100, 150, 200, 250, 300, 350, or 400° C., and can be in the range between the two values exemplified herein.

The heat treatment duration time is, for example, 0.1 to 20 hours, preferably 0.5 to 5 hours. The heat treatment duration time is, particularly for example, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 hours, and can be in the range between the two values exemplified herein.

Heat treatment can be carried out under an inert gas atmosphere such as nitrogen, or under an inert gas atmosphere containing 1 to 4% of hydrogen.

<Reduction Step>

In the reduction step, reduction treatment of the metal fine particles130is carried out after the heat treatment step. The reduction treatment can be carried out by performing a heat treatment under a reductive atmosphere containing a reductive gas such as hydrogen.

The temperature of this heat treatment is, for example, 70 to 300° C., preferably 100 to 200° C. This temperature is, particularly for example, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, or 300° C., and can be in the range between the two values exemplified herein.

The heat treatment duration time is, for example, 0.01 to 20 hours, preferably 0.1 to 5 hours. The heat treatment duration time is, particularly for example, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 hours, and can be in the range between the two values exemplified herein.

When the reductive gas is hydrogen, the concentration thereof is, for example, 0.1 to 100 volume %, preferably 0.2 to 10 volume %, and more preferably 0.5 to 3 volume %. Thins concentration is, particularly for example, 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 10, or 100 volume %, and can be in the range between the two values exemplified herein.

The metal fine particles130after the heat treatment in the supporting step can be in an oxidized condition. In such case, the metal fine particles130may not show catalyst activity. The catalyst activity can be increased by reducing the metal fine particles130.

EXAMPLES

The support and metal catalyst was manufactured in accordance with the method described below, and various evaluations were performed.

1. Manufacture of Support and Metal Catalyst100

Example 1

(Manufacture of Support Powder)

By using the manufacturing apparatus1shown inFIG.8toFIG.11, support powder was manufactured. As the burner gas2a, gas prepared by blending 5 L/min of oxygen and 1 L/min of propane gas was used. This gas was ignited to form a flame (chemical flame)7of 1600° C. or higher at the tip of the burner2. The raw material solution23awas prepared by blending titanium octylate, tin octylate, and tantalum octylate by a molar ratio of 0.40:0.60:0.10, and then the blend was further combined with mineral spirit terpen and dissolved. Oxygen was used as the mist gas13a.9 L/min of the mist gas13aand 3 g/min of the raw material solution23awere blended and sprayed from the tip of the raw material supplying unit3which is a spray nozzle (atomizer) towards the center portion of the flame, thereby allowing combustion of the blend and generation of the support powder which is an aggregate of the support fine particles150. During such, negative pressure was applied to the gas discharging portion5bto suction air from slit6bat a flow rate of 170 L/min, thereby collecting the generated support powder in the collector5(with filter5a). The raw material supplying unit3comprises a double tube structure (overall length of 322.3 mm). Oxygen is supplied from the outer cylinder13, and the raw material solution23ais supplied to the raw material distribution cylinder23. At the tip of the raw material distribution cylinder23, a fluid nozzle and an air nozzle are provided, and the raw material solution23awas converted into the mist23bat this position. The amount of the support powder collected was 10 g or more when the operation was carried out for 60 minutes.

(Support and Reduction of Metal Fine Particles (Pt)130)

In accordance with the procedures shown inFIG.12, metal fine particles130were supported onto the support powder.

First, 0.57 mL of chloroplatinic acid hexahydrate aqueous solution was dissolved in 38 ml of super pure water, followed by addition of 1.76 g of sodium carbonate, and then the mixture was agitated (Step S1ofFIG.12).

The solution was diluted with 150 ml of water, and pH of the solution was adjusted to 5 with NaOH. Thereafter, 25 ml of hydrogen peroxide was added, and the pH was again adjusted to 5 with NaOH (Step S2ofFIG.12).

To the dispersion, a dispersion prepared by dispersing 0.50 g of support powder in 15 mL of super pure water was added (Step S3ofFIG.12), and the mixture was agitated for 3 hours at 90° C. (Step S4ofFIG.12). The mixture was cooled to room temperature, and was then filtered. The residue was washed with super pure water and alcohol, and was then dried overnight at 80° C. The residue was then subjected to heat treatment at 400° C. for 2 hours under nitrogen atmosphere to support the metal fine particles130onto the support powder. Subsequently, heat treatment at 150° C. for 2 hours under 1% hydrogen atmosphere was performed to reduce the metal fine particles130(Step S5ofFIG.12). Accordingly, support and metal catalyst100as metal fine particles130supported on support powder was obtained.

Examples 2 to 5 and Comparative Examples 1 to 4

Support and metal catalyst100were manufactured in a similar manner as Example 1, except for altering the molar ratio of titanium octylate, tin octylate, and tantalum octylate as shown in Table 1.

TABLE 1ExamplesComparative Examples123451234titanium octylate0.40.50.60.70.800.20.91tin octylate0.60.50.40.30.210.80.10tantalum octylate0.10.10.10.10.10.10.10.10.1atom ratio of Ti/(Ti + Sn)0.40.50.60.70.80.00.20.91.0electric conductivitysupport7.56E−071.95E−061.35E−061.68E−062.41E−056.83E−071.83E−062.21E−061.71E−06(S/cm)powdersupport and4.49E−021.44E−024.13E−023.60E−022.49E−021.00E−023.93E−031.25E−053.20E−07metal catalyst
2. Measurement of Electric Conductivity

With the Examples and Comparative Examples, electric conductivity of the support powder before supporting the metal fine particles130and electric conductivity of the support and metal catalyst100after supporting the metal fine particles130were measured. Results are shown in Table 1 andFIG.13.

As shown in Table 1 andFIG.13, the support and metal catalyst100according to the Examples had higher electric conductivity compared with the support and metal catalyst100according to the Comparative Examples. In addition, the atom ratio of Ti/((Ti+Sn) had greater influence on the electric conductivity in the support and metal catalyst100, compared with the support powder.

The method for measuring the electric conductivity is as follows.

Support and metal catalyst or support powder were weighed precisely by the same weight using a precise electronic balance to prepare 8 samples (hereinafter referred to as “target sample”). The 8 samples were each filled into 8 sample holders (3 mm diameter, 5 mm depth) in the measurement tool, respectively. The measurement tool filled with the target samples was set in a pressure device, and the target samples were compressed with a force of 1.1 kN. By using the electrode provided with the compression tool of the pressure device, the resistance of the target sample during compression was measured by the DC two-terminal method, and the length of the target sample was also measured at the same time. These procedures were performed with 4 or more kinds of target samples with different weight. The relation between the length of the target sample (x axis) and resistance (y axis) during compression was obtained, and extrapolation towards the y axis was performed to obtain the y intercept. The specific resistance of the target sample was obtained from the value of the y intercept, length and cross-sectional area of the compressed powder. The electric conductivity was calculated as the inverse of the specific resistance.

EXPLANATION OF SYMBOLS

1: manufacturing apparatus,2: burner,2a: burner gas,3: raw material supplying unit,4: reaction cylinder,5: collector,5a: filter,5b: gas discharging portion,6: gas reservoir,6a: cold gas introducing portion,6b: slit,6c: inner peripheral wall,6d: burner insertion hole,6g: cold gas,7: flame,13: outer cylinder,13a: mist gas,20: fuel cell,23: raw material distribution cylinder,23a: raw material solution,23b: mist,100: support and metal catalyst,110: void,120: crystallite,130: metal fine particles,150: support fine particles,160: branch,200: fuel cell,201: anode,202: cathode,203: load,210A: gas diffusion layer on anode side,210K: gas diffusion layer on cathode side,220A: catalyst layer on anode side,220K: catalyst layer on cathode side