JP5205434B2 - Cathode catalyst layer, membrane electrode assembly, and fuel cell - Google Patents

Description

  Embodiments of the present invention relate to a catalyst, a catalyst composition, a cathode catalyst layer, a membrane electrode assembly, and a fuel cell.

  As the catalyst, a conductive carrier carrying a catalyst metal such as platinum (Pt), a metal oxide or a metal compound is used, and a fuel cell containing this catalyst and a polymer electrolyte is used. It is used for various applications such as a catalyst layer.

  For example, a fuel cell is a system that generates power by electrochemically reacting a fuel (for example, hydrogen) and an oxidant (for example, oxygen). Since the product of this reaction is water in principle, there is little load on the environment. Among them, the polymer electrolyte fuel cell is developed and put to practical use as a stationary power source for home use because it can operate at a lower temperature than other fuel cells.

  Such a polymer electrolyte fuel cell is supplied with a polymer electrolyte membrane having hydrogen ion conductivity, and two electrodes sandwiching the membrane, that is, a fuel electrode (anode) to which hydrogen is supplied and oxygen. It is called a membrane electrode assembly (MEA) having a basic configuration in which an air electrode (cathode) is arranged.

Japanese Patent Laying-Open No. 2005-071760

  The problem to be solved by the present invention is to provide a catalyst, a catalyst composition, a cathode catalyst layer, a membrane electrode assembly, and a fuel cell containing a non-platinum catalyst having excellent chemical stability and high catalytic activity in an acidic atmosphere. It is to be.

Cathode catalyst layer embodiment of the present invention includes a catalytic composition, characterized by containing a polymer electrolyte.
This catalyst composition contains a catalyst and a conductive material.
The catalyst includes at least one element L selected from rare earth elements and at least selected from the group consisting of boron (B), phosphorus (P), molybdenum (Mo), tungsten (W), and sulfur (S). A rare earth oxoacid salt carrier containing one element X, and a group consisting of manganese (Mn), iron (Fe), cobalt (Co) and nickel (Ni) supported on the surface of the rare earth oxoacid salt carrier It is a composite containing the oxide particle containing the element M which consists of at least 1 type selected from these.

  Moreover, the membrane electrode assembly of the embodiment of the present invention is characterized by using the cathode catalyst layer of the present invention.

  The fuel cell according to the embodiment of the present invention is characterized by using the membrane electrode assembly of the present invention.

It is a figure which shows the structure of the fuel cell of embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
For example, a fuel cell is a system that generates electricity by electrochemically reacting hydrogen (fuel) and oxygen. Since the product of this reaction is water in principle, there is little load on the environment. Solid polymer fuel cells have been developed and put to practical use as stationary power sources for home use because they can operate at lower temperatures than other fuel cells.

  A polymer electrolyte fuel cell has a polymer electrolyte membrane having hydrogen ion conductivity, and two electrodes sandwiching the membrane, that is, an anode to which hydrogen is supplied and a cathode to which oxygen is supplied It has MEA with the basic configuration. The electrode is a porous layer formed by a mixture of a catalyst for promoting an electrochemical reaction, an electron conductive material, and a solid polymer electrolyte having ion conductivity, and is called a catalyst layer.

  In MEA, as shown in the following chemical formula, hydrogen, which is a fuel, is oxidized at the anode to generate hydrogen ions and electrons. Hydrogen ions pass through the solid polymer electrolyte membrane and move to the cathode, and electrons move to the cathode via an external circuit. At the cathode, oxygen contained in the oxidant gas is reduced by hydrogen ions and electrons to generate water. A polymer electrolyte fuel cell directly obtains electric energy from reaction energy obtained by an electrochemical reaction.

Anode reaction (fuel electrode): H ₂ → 2H ⁺ + 2e ⁻
Cathode reaction (air electrode): 2H ⁺ + 2e ⁻ + 1 / 2O ₂ → H ₂ O
Such a polymer electrolyte fuel cell has the merit that it is not necessary to use a high-temperature heat-insulating material because it can generate low-temperature power, but it must be a platinum catalyst using platinum (Pt) having a high catalytic function. There is a demerit that must be done.

  Since platinum catalysts are expensive, they are a major challenge for the spread of fuel cells. In general, Pt is considered to be chemically stable, but Pt used as a cathode catalyst dissolves as ions in an acidic oxidizing atmosphere such as in a strongly acidic electrolyte. As a result, long-term stable power generation becomes difficult. In order to reduce metal elution from the catalyst, it is necessary to reduce the amount of strongly acidic electrolyte used in the catalyst layer. However, when the amount used is reduced, there is a problem that proton conductivity is lowered and high output cannot be obtained.

  On the other hand, if the amount of platinum catalyst is reduced for cost reduction, there is a problem that the battery life itself is further shortened. In order to reduce the cost and increase the life of a fuel cell, it is essential to develop a non-platinum catalyst having high oxygen reduction characteristics and stability in place of Pt.

  Non-platinum catalysts are required to have excellent chemical stability and high oxygen reduction activity in an acidic atmosphere such as in a strongly acidic electrolyte, particularly at the cathode. However, conventional metal oxides and metal compounds have a problem of lacking in chemical stability such as elution in a strongly acidic atmosphere, and since the activity is not satisfactory, cathode catalysts other than Pt and Pt alloys are used. As of now, no effective one has been found.

  The catalyst layer of the fuel cell has a strong acidic atmosphere (about pH = 1) with a strong acidic electrolyte such as Nafion (registered trademark of DuPont), which is an electrolyte. With some exceptions, transition metal oxides can dissolve in the catalyst layer. Similarly, sulfates of alkali metals, transition metals, and rare earth metals are easily dissolved. In addition, transition metal oxides and sulfates do not have oxygen reduction catalytic activity except for a part.

  In order to solve the above-mentioned problems, the present inventors have studied various compositions as a catalyst, and as a result, have arrived at the present invention. Specifically, by supporting the transition metal oxide on the rare earth sulfate, the chemical stability of the transition metal oxide and the rare earth metal sulfate can be suppressed in a strongly acidic environment (pH = 1). It has been found that oxygen reduction activity is exhibited.

  The catalyst according to the embodiment of the present invention includes a rare earth containing at least one element L selected from rare earth elements and at least one element X selected from the group consisting of B, P, Mo, W and S. A composite containing an oxoacid carrier and oxide particles supported on the surface of the rare earth oxoacid salt carrier and containing at least one element M selected from the group consisting of Mn, Fe, Co, and Ni It is characterized by being.

  Each configuration in the present invention will be described below.

  The rare earth metal oxoacid salt carrier of the embodiment of the present invention is based on a salt composed of at least one element L selected from rare earth elements and an oxoanion.

As rare earth elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), eurobium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), It is the element L which consists of at least 1 type selected from the group of horbium (Ho), erbium (Er), thulium (Tm), ytterbium ( Yb ), and lutetium (Lu).

The oxoanion is formed by XO _n ^{(2n−x) −} (where n is an element X ⁾ formed by combining at least one element X selected from the group consisting of B, P, Mo, W and S with oxygen. The number of oxygen atoms bonded to x, and x represents the oxidation number of element X).

  In the present invention, the catalytic mechanism of the detailed oxygen reduction catalyst of the catalyst has not yet been elucidated, but the transition caused by the bond generated between the oxoanion of the rare earth metal oxoacid salt support and the metal element of the transition metal oxide The electronic state of the metal element may be affected, and the transition metal element may have a catalytic activity. Furthermore, it is thought that it can have chemical stability that does not dissolve even in a strongly acidic environment. Furthermore, since it is possible to suppress the transition metal ions from the transition metal oxide from being eluted in the state of the transition metal, contamination of other fuel cell materials and devices can be avoided. Therefore, according to the present invention, high long-term reliability can be obtained in the fuel cell.

  The element L constituting the rare earth metal oxoacid salt carrier is preferably La. The element X is preferably S.

  The element M constituting the oxide particles is preferably Co.

  In the embodiment of the present invention, the element ratio (M / (L + X)) between the element L and the element M with respect to the precursor X is preferably in the range of 0.01 to 2 (mol ratio).

  This is because if the element ratio of the element L to the element M with respect to the precursor X (M / (L + X)) is too small, the active sites necessary for the catalytic reaction are insufficient, and sufficient catalytic performance cannot be obtained. On the contrary, if the element ratio (M / (L + X)) is too large, the surface of the rare earth metal oxoacid salt alone is covered with excess transition metal oxide, and the catalytic activity is reduced. Therefore, the element ratio (M / (L + X)) is set in the above range. A preferable element ratio is 0.05 to 1, and more preferably 0.2 to 0.9.

  In the catalyst of the embodiment of the present invention, the shape and size are not particularly limited, and those having a known catalyst shape and size can be used.

  In addition, since the effective electrode area which an electrochemical reaction advances increases so that the average particle diameter of a catalyst is small, the reaction current value obtained by catalytic activity and catalytic reaction becomes high, and is preferable. The catalyst of the present invention has an amorphous shape close to a sphere, and the average particle size is preferably 5 nm to 300 nm, more preferably 10 nm to 50 nm.

  The composition analysis of the catalyst in the embodiment of the present invention can be evaluated by inductively coupled plasma emission spectroscopy (ICP). The analysis sample can be evaluated by a powder sample obtained by scraping a part of the catalyst layer used for the synthesized electrode catalyst or the cathode of the fuel cell.

There are several methods for the pretreatment (solution) of the analysis sample, and these can be used in appropriate combinations according to the elements used in the catalyst of the present invention. For example, in the case of an acid dissolution method, concentrated hydrochloric acid that forms a complex with many elements to assist dissolution, nitric acid having strong oxidizing power, hot concentrated sulfuric acid capable of high-temperature heat decomposition, and the like can be used. Further, when it is difficult to dissolve with a single acid, a mixed acid obtained by combining these acids may be used. In the case where acid decomposition is difficult, there is an alkali melting method having strong dissolving power by high-temperature melting, and Na ₂ CO ₃ , Na ₂ O ₂ , NaOH + NaNO _{3 and the} like can be used as the decomposing agent.

  Confirmation that the oxide particles are supported on the rare earth oxoacid salt carrier is based on the energy dispersive X-ray spectroscopic analysis (EDS: Energy Dispersive X-ray) of the particles observed with a transmission electron microscope (TEM). ray Spectroscopy). In the present invention, JEM-200CX manufactured by JEOL Ltd. is used for the transmission electron microscope image (TEM), and the observation is performed at an acceleration voltage of 200 kV and a magnification of 330,000 times. Specifically, it is confirmed by directly observing the image that the genus oxide particles are adhered to the rare earth oxoacid salt carrier, and composition analysis is performed using spots by energy dispersive X-ray spectroscopy (EDS). This is confirmed by detecting the constituent elements of the transition metal oxide from the surface of the rare earth metal sulfate particles.

  Moreover, the crystal structure of the catalyst in the embodiment of the present invention can be confirmed by assigning a diffraction peak in X-ray diffraction analysis (XRD). In the present invention, RINT1200 manufactured by Rigaku is used for the X-ray diffraction analysis (XRD) apparatus.

  The sample can be evaluated by a powder sample obtained by cutting out a part of the catalyst layer used for the synthesized catalyst or the cathode of the fuel cell.

  The analysis sample was pulverized in an agate mortar and used a powder that passed through a 45 μm sieve. In the measurement, a glass sample plate (size of sample portion: length 20 mm × width 20 mm × depth 0.2 mm) was filled with a glass plate so that the analysis sample was smooth with the surface of the sample plate.

  The measurement conditions are as follows. For details on other measurement methods, refer to “Guidelines for X-ray diffraction (revised third edition)” issued by Rigaku Denki Co., Ltd.

Tube: Cu
Tube voltage: 40 kV
Tube current: 40 mA
Divergence slit: 1 deg
Scattering slit: 1 deg
Receiving slit: 0.30mm
Sampling angle: 0.020 deg
Scan speed: 2 deg / min
The average particle diameter of the catalyst component in the embodiment of the present invention can be calculated from the crystallite diameter obtained from the half width of the strongest diffraction peak of the catalyst component in X-ray diffraction analysis (XRD). The Scherrer equation was used for the calculation.

  When the sample is taken out from the catalyst, the cross section of the substantially central portion of the surface having the maximum surface area of the product is used.

  Next, the manufacturing method of the catalyst of the 1st Embodiment of this invention is demonstrated.

As the rare earth metal oxoacid salt, commercially available products may be used. Alternatively, an aqueous solution of rare earth metal nitrate with an oxo acid aqueous solution, specifically boric acid (H ₃ BO ₃ ), phosphoric acid (H ₃ PO ₄ ), molybdic acid (H ₂ MoO ₄ ), tungstic acid (H ₂ WO ₄ ) A rare earth metal oxo acid salt synthesized by adding an aqueous solution of sulfuric acid (H ₂ SO ₄ ) or an ammonium salt of these oxo acids and removing the aqueous solvent and then calcining may be used. The method for synthesizing the rare earth oxoacid salt is not limited to these. The rare earth metal oxoacid salt may be a composite salt containing a plurality of types of rare earth metal elements. Since rare earth metal elements have close atomic radii, the crystal structure is acceptable as a composite salt. Of these, it is desirable to use lanthanum sulfate in order to sufficiently increase the catalytic activity.

  A method of supporting an oxide containing element M using the obtained rare earth metal oxoacid salt as a carrier is a solution in which a salt containing element M is dissolved in an aqueous solution in which rare earth metal oxoacid salt is dissolved or dispersed, for example, chloride. A mixture of a rare earth metal oxoacid salt and a salt containing a transition metal element M is obtained as a catalyst precursor by mixing an aqueous solution of the product, nitrate, acetate and the like and removing the solvent.

  The catalyst precursor is pulverized and then heat treated to thermally decompose the salt containing the transition metal element M into an oxide containing the element M, and the transition metal oxide is supported using the rare earth metal oxoacid salt as a support. The Furthermore, a bond is formed between the rare earth metal oxoacid salt and the transition metal oxide, which becomes the catalyst of the present invention. As a method for removing the solvent from the solution in which the salt containing the rare earth metal oxoacid salt and the element M is dissolved, a solvent is used by using a known method such as natural drying, evaporation to dryness, rotary evaporator, spray dryer, drum dryer or the like. May be removed. What is necessary is just to select the time and temperature of solvent removal suitably according to the method to be used.

  The temperature of the heat treatment when the transition metal oxide is supported on the rare earth metal oxoacid salt support is obtained by thermally decomposing a salt containing the element M, for example, chloride, nitrate, acetate, etc. to obtain an oxide containing the element M. The oxide containing element M is necessary to form a chemical bond with the rare earth metal oxoacid salt. Therefore, the heat treatment conditions are determined by the thermal decomposition temperature of the salt containing the element M and the optimum temperature at which the oxide forms a bond with the rare earth metal oxoacid salt. The heat treatment temperature is 400 to 1000 ° C. If the heat treatment temperature is too low, the salt containing the element M is not sufficiently decomposed to form an oxide, or even if it is an oxide, it does not form a sufficient bond with the rare earth metal oxoacid salt support. As a result, the catalytic activity is lowered. Also, if the heat treatment temperature becomes too high, oxides containing element M and rare earth metal oxoacid salts will grow and the reaction area will decrease due to the reduction of the specific surface area of the catalyst and the rare earth metal oxoacid salts will thermally decompose. It becomes an oxide and the catalyst is deactivated. Therefore, the heat treatment temperature is in the above range. The heat treatment temperature is preferably 500 to 800 ° C, more preferably 550 to 700 ° C.

  The oxide particles containing the rare earth metal oxoacid salt support and the element M function as a catalyst by forming the chemical bond as described above. The heat treatment described above is essential for the synthesis of the catalyst, and the oxide particles containing the rare earth metal oxoacid salt and the element M are crystallized in the firing process.

  The atmosphere of the heat treatment in which the oxide particles containing the element M are supported on the rare earth metal oxo acid salt includes a salt containing the element M, for example, an oxide containing a transition metal element by thermally decomposing a chloride, nitrate, acetate or the like. Therefore, the treatment is preferably performed in an oxidizing atmosphere such as air or oxygen.

  The method for supporting the oxide particles containing the element M on the rare earth metal oxoacid salt support is not limited to these. The oxide particles may be in the form of a complex oxide containing a plurality of elements. Of these, it is preferable to use a cobalt oxide in order to sufficiently increase the catalytic activity.

The catalyst of the embodiment of the present invention has excellent catalytic activity, but is particularly preferably used as a cathode catalyst because of its excellent oxygen reduction activity represented by 2H ⁺ + 2e ⁻ + 1 / 2O ₂ → H ₂ O and the like. .

  With the catalyst of the first embodiment, it is possible to obtain a catalyst including a non-platinum catalyst that is excellent in chemical stability under an acidic atmosphere and has high catalytic activity.

(Second Embodiment)
Next, the catalyst composition of 2nd Embodiment concerning this invention is demonstrated.

  The catalyst of the present invention shown in the first embodiment does not have conductivity. Therefore, in order to promote the electrode reaction, the catalyst is used as a catalyst composition containing a conductive material.

  The conductive material is not particularly limited as long as it has a specific surface area for supporting the electrode catalyst in a desired dispersed state and has sufficient electronic conductivity as a current collector. Preferably there is. For example, carbon black such as acetylene black, Vulcan (registered trademark of Cabot Corporation), ketjen black, and the like can be mentioned. However, the present invention is not limited to this, and any carrier having excellent conductivity and stability can be used. Can do. Recently, nanocarbon materials, such as fibers, tubes, coils, etc., have been developed.

The specific surface area of the conductive material may be sufficient as long as the catalyst is highly dispersed and supported. It is a 50m ² / g~1400m ² / g. If the specific surface area is too small, the dispersibility of the catalyst component in the conductive material may be reduced and sufficient power generation performance may not be obtained. Conversely, if the specific surface area is too large, the effective utilization rate of the catalyst component will be reduced. There is a fear. Therefore, it was set as the said range. Preferred specific surface area was ^{80m 2} / ^g~1200m 2 / g, more preferably from 100m ² / g~1000m ² / g.

  The size of the conductive material is not particularly limited, but the average diameter is preferably 30 nm to 500 nm, preferably from the viewpoint of controlling the ease of loading on the rare earth oxoacid salt support and the catalyst utilization rate within an appropriate range. Is preferably about 50 nm to 300 nm. The magnitude | size of an electroconductive material can be measured by the average value of the particle diameter of the electroconductive material investigated from a transmission electron microscope image (TEM).

  The catalyst content in the catalyst composition of the second embodiment of the present invention is preferably 10 to 90% by mass with respect to the total amount of the catalyst composition. If the catalyst content is too low, the catalyst activity per unit mass is reduced, and a large amount of electrode catalyst is required to obtain the desired catalyst activity, and the diffusibility of the reactants in the catalyst layer is reduced, which is not preferable. . On the contrary, if the content of the catalyst is too large, the degree of dispersion of the catalyst on the conductive material is lowered, so that the electric resistance increases and the activity may be lowered. The catalyst content is preferably 20 to 80% by mass, and more preferably 30 to 70% by weight. It is good to do. The content of the electrode catalyst can be examined by inductively coupled plasma emission spectroscopy (ICP).

  In order to obtain a catalyst composition containing the catalyst of the embodiment of the present invention and a conductive material, the obtained catalyst and the conductive material may be mixed.

  With the catalyst composition of the second embodiment, a catalyst composition containing a non-platinum catalyst having excellent chemical stability and high catalytic activity under an acidic atmosphere can be obtained.

(Third embodiment)
Next, the catalyst composition of 3rd Embodiment concerning this invention is demonstrated.

  A third embodiment (second catalyst composition) of the present invention includes the catalyst shown in the first embodiment and an oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material. It is a catalyst composition containing.

  In the third embodiment, the amount of Pt used can be greatly reduced by mixing with an oxygen reduction catalyst containing known noble metal particles and / or noble metal alloy particles that are conventionally used. In addition, the electrode reaction by the electrode catalyst of the present invention is promoted, and a catalyst composition having further excellent catalytic activity can be obtained.

  The oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on the conductive material is not particularly limited as long as it is a conventionally known oxygen reduction catalyst.

  The noble metal particles are not particularly limited, and those composed of at least one kind of noble metal selected from the group consisting of platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), and iridium (Ir). preferable.

  Further, in order to improve the dissolution resistance, activity, etc. of the catalyst, noble metal alloy particles may be used as the catalyst component. Although it does not restrict | limit especially as a noble metal alloy particle, The alloy which consists only of 2 or more types of noble metal elements, the alloy containing a noble metal element and another metal element, etc. are mentioned.

  Since the noble metal alloy particles have high catalytic activity, a noble metal alloy catalyst based on Pt is preferable. Specifically, as the noble metal alloy catalyst, a group consisting of noble metals other than Pt such as Ru, Rh, Pd, and Ir, titanium (Ti), vanadium (V), chromium (Cr), Mn, Fe, Co, and Ni. An alloy of at least one metal element selected from Pt and Pt is preferable.

  The alloy composition of the noble metal alloy particles is preferably 30 to 95 atomic% for Pt and 5 to 70 atomic% for the metal element to be alloyed, depending on the type of metal element to be alloyed.

  Note that an alloy is a generic name for a plurality of metal elements or those having metallic properties composed of a metal element and a non-metal element. Alloys include solid solutions that are completely dissolved, eutectics in which the metallic elements of the components are independent at the crystal level, and intermetallic compounds that are bonded at a certain ratio at the atomic level. It is not limited to.

  In the case of using both noble metal particles and noble metal alloy particles as catalyst components in an oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material, the noble metal particles and the noble metal alloy particles are supported on the same conductive material. Each of them may be supported on different conductive materials.

  In the oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on the conductive material of the catalyst composition of the third embodiment, the loading amount of the metal component such as noble metal particles and / or noble metal alloy particles is oxygen reduction. It is preferable that it is 10-90 mass% with respect to the whole quantity of a catalyst. This is because if the amount of the metal component supported is too small, the catalytic activity per unit mass decreases, and a large amount of electrode catalyst is required to obtain the desired power generation performance, and the diffusibility of the reactants in the catalyst layer decreases. Therefore, it is not preferable. On the other hand, if the amount is too large, the degree of dispersion of the catalyst component on the conductive material is lowered, and the improvement in power generation performance is small and the economic advantage may be reduced for an increase in the amount supported. Therefore, the carrying amount is in the above range. A preferable loading amount is 20 to 80% by mass, and more preferably 30 to 70% by mass.

  Moreover, it is preferable that content of the catalyst of this invention shown by 1st Embodiment of the catalyst composition of 3rd Embodiment is 30-97 mass% with respect to the whole quantity of a catalyst composition. This is because, when the content of the catalyst of the present invention is too small, oxygen reduction by the composite containing oxide particles containing the element M supported on the surface of the rare earth oxoacid salt carrier shown in the first embodiment This is because the activity may not be sufficiently expressed, and conversely if the content is too large, the oxygen reduction activity by the noble metal particles and the noble metal alloy particles may not be sufficiently expressed. The preferable content of the catalyst of the present invention shown in the first embodiment is 40 to 95% by mass, more preferably 50 to 93% by mass.

  With the catalyst composition of the third embodiment, a catalyst composition containing a non-platinum catalyst having excellent chemical stability and high catalytic activity in an acidic atmosphere can be obtained.

(Fourth embodiment)
Next, a cathode catalyst layer according to a fourth embodiment of the present invention will be described.

  The fourth embodiment of the present invention uses the catalyst composition of the second embodiment and the third embodiment.

  The cathode catalyst layer has the same configuration as that of a conventional general electrode catalyst layer except that the catalyst composition of the present invention and a polymer electrolyte are used.

  The polymer electrolyte used for the cathode catalyst layer according to the fourth embodiment of the present invention is not particularly limited, and a known one can be used, but at least a member having high proton conductivity and chemical stability can be used. It ’s fine. The solid polymer electrolyte that can be used as the polymer electrolyte is a perfluorocarbon sulfonic acid system such as Nafion (registered trademark of DuPont) as a fluorine-based electrolyte containing fluorine atoms in all or part of the polymer skeleton. Polymers.

  In the cathode catalyst layer of the embodiment of the present invention, the content of the catalyst composition is 5 to 97% by mass with respect to the total amount of the cathode catalyst layer components (total of the catalyst composition and the polymer electrolyte). preferable. This is because the content of the catalyst composition is too low, the catalyst composition is insufficient, and sufficient power generation performance may not be obtained. On the other hand, when the content is too high, the polymer electrolyte is insufficient and the proton conductivity is reduced. This is because sufficient power generation performance may not be obtained due to insufficient performance. The preferable content of the catalyst composition is 7 to 95% by mass, more preferably 10 to 90% by mass.

  In the cathode catalyst layer including the electrode catalyst according to the embodiment of the present invention, the cathode catalyst layer may have a two-layer structure, and one of the cathode catalyst layers may include the electrode catalyst.

  The cathode catalyst layer according to the embodiment of the present invention may be formed by laminating a cathode catalyst layer having a plurality of compositions in the thickness direction of the cathode catalyst layer. For example, a cathode catalyst layer containing the catalyst composition of the present invention and a polymer electrolyte and a cathode catalyst layer containing an oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material and a polymer electrolyte are laminated. It is also possible to adopt the configuration described above.

  The cathode catalyst layer according to the embodiment of the present invention is, for example, mixed and dispersed in the organic solvent such as water or alcohol to form the catalyst material, and this slurry is applied to a substrate (such as a conductive porous sheet). Dry to form a catalyst layer. The dispersion method is not particularly limited, and examples thereof include a dissolver and a ball mill.

  The cathode catalyst layer of the embodiment of the present invention can secure a gap for sufficiently diffusing a reaction gas such as an oxidant gas. Accordingly, the oxygen reduction activity of the catalyst can be further improved. Further, by using a conductive material having sufficient electronic conductivity as a current collector, the electrode reaction is not hindered.

  As described above, the power generation performance and durability of the cathode catalyst layer according to the embodiment of the present invention can be further improved.

(Fifth embodiment)
Next, a membrane electrode assembly and a fuel cell according to a fifth embodiment of the present invention will be described.

  The fifth embodiment of the present invention uses the cathode catalyst layer of the fourth embodiment.

  FIG. 1 is a cross-sectional view schematically showing a membrane electrode assembly (MEA) of a fifth embodiment and a fuel cell using the same.

  The fuel cell 20 includes a polymer electrolyte membrane 1 having hydrogen ion conductivity, and two electrodes sandwiching the membrane 1, that is, a fuel electrode (anode) 2 to which hydrogen is supplied and an air electrode (to which oxygen is supplied). A membrane electrode assembly (MEA) 12 having a basic configuration of a cathode 3 is disposed. The anode 2 includes a diffusion layer 4 and an anode catalyst layer 5 laminated thereon. The cathode 3 includes a diffusion layer 6 and a cathode catalyst layer 7 laminated thereon. The anode 2 and the cathode 3 are laminated so that the anode catalyst layer and the cathode catalyst layer face each other with the polymer electrolyte membrane 1 interposed therebetween.

  The MEA 12 has a cathode holder 9 with an oxidant gas supply groove 8 for supplying air (oxygen) to the cathode from a supply mechanism for supplying oxidant such as air (oxygen) (not shown), and hydrogen as fuel to the anode. A single cell as shown in FIG. 1 is built in the anode holder 11 with the fuel supply groove 10 for supply to generate electric power. In the fuel cell 20, a stack structure or a planar arrangement structure in which a plurality of MEAs 12 are stacked and connected in series via the cathode holder 9 and the anode holder 11 so as to obtain a desired voltage or the like is formed. Also good. The shape of the fuel cell 20 is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  The cathode catalyst layer 7 is constituted by the cathode catalyst layer of the fourth embodiment.

  The cathode catalyst layer 7 may be formed by laminating a cathode catalyst layer having a plurality of compositions in the thickness direction of the cathode catalyst layer. For example, the first cathode catalyst layer is a cathode catalyst layer containing the catalyst composition of the present invention and a polymer electrolyte, and the second cathode catalyst layer has noble metal particles and / or noble metal alloy particles supported on a conductive material. A structure in which a cathode catalyst layer containing an oxygen reduction catalyst and a polymer electrolyte is laminated can also be adopted.

  By adopting the cathode catalyst layer 7 having this laminated structure, it is possible to provide a cathode catalyst layer with further improved power generation performance or durability. For example, when the MEA 12 is configured using the cathode catalyst layer 7 having the above-described stacked structure, the first cathode catalyst layer is disposed on the polymer electrolyte membrane 1 side, so that the excess generated by the side reaction of the electrode reaction is generated. The decomposition of hydrogen oxide is promoted by the catalyst of the present invention, whereby deterioration of the electrolyte components contained in the cathode catalyst layer 7 and the polymer electrolyte membrane 1 due to hydrogen peroxide can be suppressed, and the cathode catalyst layer 7 and the MEA 12 The durability can be further improved.

  In addition, when the MEA 12 is configured using the cathode catalyst layer 7 having the laminated structure, the first cathode catalyst layer is disposed on the side opposite to the polymer electrolyte membrane 1 to retain water generated by power generation. By playing a role as a water retaining layer, the burden of managing the humidification conditions of the fuel cell 20 can be reduced, and stable power generation can be performed for a long period of time.

  The anode catalyst layer 5 contains a fuel oxidation catalyst and a polymer electrolyte in which noble metal particles and / or noble metal alloy particles are supported on a conductive material.

  In the anode catalyst layer 5, the fuel oxidation catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material is not particularly limited as long as it is generally used. Specifically, the noble metal particles are preferably made of at least one kind of noble metal selected from the group consisting of Pt, Ru, Ir, and Pd.

  Further, noble metal alloy particles may be used as a catalyst component in order to suppress a decrease in catalyst activity due to a catalyst poisoning component contained in the fuel gas, such as carbon monoxide.

  The noble metal particles are not particularly limited, but those composed of at least one kind of noble metal selected from the group consisting of Pt, Ru, Rh, Pd, and Ir are preferable.

  Further, in order to improve the dissolution resistance, activity, etc. of the catalyst, noble metal alloy particles may be used as the catalyst component. Although it does not restrict | limit especially as a noble metal alloy particle, The alloy which consists only of 2 or more types of noble metal elements, the alloy containing a noble metal element and another metal element, etc. are mentioned.

  Since the noble metal alloy particles have high catalytic activity, a noble metal alloy catalyst based on Pt is preferable. Specifically, the noble metal alloy catalyst includes one or more metal elements selected from the group consisting of noble metals other than Pt such as Ru, Rh, Pd, and Ir, Ti, V, Cr, Mn, Fe, Co, and Ni. An alloy with Pt is preferred.

  The alloy composition of the noble metal alloy particles is preferably 30 to 95 atomic% for Pt and 5 to 70 atomic% for the metal element to be alloyed, depending on the type of metal element to be alloyed.

  Note that an alloy is a generic name for a plurality of metal elements or those having metallic properties composed of a metal element and a non-metal element. Alloys include solid solutions that are completely dissolved, eutectics in which the metallic elements of the components are independent at the crystal level, and intermetallic compounds that are bonded at a certain ratio at the atomic level. It is not limited to.

  In a fuel oxidation catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material, when both noble metal particles and noble metal alloy particles are used as catalyst components, the noble metal particles and the noble metal alloy particles are supported on the same conductive material. Each of them may be supported on different conductive materials.

  In the fuel oxidation catalyst in which noble metal particles and / or noble metal alloy particles are supported on the conductive material of the anode catalyst layer 5, the supported amount of metal components such as noble metal particles and / or noble metal alloy particles is based on the total amount of the oxygen reduction catalyst. The content is preferably 10 to 90% by mass. This is because if the amount of the metal component supported is too small, the catalytic activity per unit mass decreases, and a large amount of electrode catalyst is required to obtain the desired power generation performance, and the diffusibility of the reactants in the catalyst layer decreases. Therefore, it is not preferable. On the other hand, if the amount is too large, the degree of dispersion of the catalyst component on the conductive material is lowered, and the improvement in power generation performance is small and the economic advantage may be reduced for an increase in the amount supported. Therefore, the carrying amount is in the above range. A preferable loading amount is 20 to 80% by mass, and more preferably 30 to 70% by mass.

  For the diffusion layers 4 and 6, a conductive porous sheet can be used. The diffusion layers 4 and 6 are disposed on the surface opposite to the surface of the electrocatalyst layers 5 and 7 on which the polymer electrolyte membrane 1 is in contact.

  The diffusion layers 4 and 6 are not particularly limited, and known ones can be used in the same manner, for example, those made of a sheet-like base material having conductivity and porosity such as carbon woven fabric, felt, and non-woven fabric. Can be mentioned.

  The thickness of the base material is appropriately determined in consideration of the characteristics of the obtained diffusion layers 4 and 6, but may be about 30 μm to 500 μm. If the thickness of the diffusion layers 4 and 6 is too thin, sufficient mechanical strength may not be obtained. Conversely, if the thickness is too thick, the distance through which gas or water permeates becomes undesirably long. Therefore, the thickness of the diffusion layers 4 and 6 is set in the above range. The thickness of a preferable base material is 35 μm to 480 μm, more preferably 40 μm to 450 μm.

  The base material contains a water repellent for the purpose of further improving water repellency, causing water generated by power generation to be clogged without being discharged from the inside of the catalyst layer, and preventing a so-called flooding phenomenon. It is preferable. Although it does not specifically limit as said water repellent, Fluorine-type, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Examples include polymer materials.

  In order to further improve the water repellency, the diffusion layers 4 and 6 have a carbon particle layer made of an aggregate of carbon particles containing a water repellent agent in the middle of the catalyst layers 5 and 7 on the substrate. There may be.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black and graphite. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area.

  Examples of the water repellent used for the carbon particle layer include the same water repellent used for the substrate. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

  The mixing ratio of the carbon particles and the water repellent in the carbon particle layer is that there is a possibility that water repellency may not be sufficiently obtained if there are too many carbon particles, and there is a risk that electronic conductivity will be reduced if there is too much water repellent. There is. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon layer is preferably 90:10 to 30:70 in terms of mass ratio.

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer, but is preferably 1 to 100 μm, more preferably 5 to 50 μm.

  The polymer electrolyte membrane 1 used for the MEA 12 of the embodiment of the present invention is not particularly limited, and examples thereof include a membrane made of the same polymer electrolyte as that used for the electrode catalyst layer. In addition, a perfluorosulfonic acid membrane represented by Nafion (registered trademark of DuPont) and the like can be mentioned.

  The thickness of the polymer electrolyte membrane 1 may be appropriately determined in consideration of the characteristics of the MEA 12 to be obtained, and preferably 5 to 300 μm, more preferably 10 to 150 μm. The thickness is preferably 5 μm or more from the viewpoint of strength at the time of film formation and durability at the time of MEA 12 operation, and is preferably 300 μm or less from the viewpoint of output characteristics at the time of MEA operation.

  The anode and cathode can be formed by a known production method.

  For example, each constituent material is mixed and dispersed in an organic solvent such as water or alcohol to form a catalyst slurry, and this slurry is applied to a conductive porous sheet and dried to form each catalyst layer. The dispersion method is not particularly limited, and examples thereof include a dissolver and a ball mill.

  In addition, for example, the catalyst composition is deposited on the base material by passing the dispersion liquid in which the catalyst composition is dispersed in water through the conductive and porous sheet-like base material, and then the polymer. The catalyst layer is formed by impregnating and drying the electrolyte solution. A homogenizer etc. are mentioned for disperse | distributing a catalyst composition in water.

The polymer electrolyte membrane 1 is joined to the anode 2 and the cathode 3 using an apparatus that can be heated and pressurized. Generally, it is performed by a hot press machine. The press temperature in that case should just be more than the glass transition temperature of the polymer electrolyte used as a binder for an electrode and an electrolyte membrane, and is generally 100-400 degreeC. The press pressure depends on the hardness of the electrode used, but is usually 5 to 200 kg / cm ² .

  As described above, the membrane electrode assembly and the fuel cell according to the embodiment of the present invention can further improve the power generation performance and durability.

  The fuel cell of the embodiment of the present invention has been described above by taking a polymer electrolyte fuel cell as an example, but is not limited thereto, and is not limited to this, and is an acid electrolyte represented by a direct methanol fuel cell and a phosphoric acid fuel cell. It can be used for various fuel cells such as fuel cells. Especially, since it is possible to achieve high density and high output, it is preferably applied to a polymer electrolyte fuel cell.

  The fuel cell is useful as a power source for a moving body such as an automobile having a limited mounting space in addition to a stationary power source. Among these, it is particularly preferable to use as a power source for a mobile body such as an automobile because the manufacturing cost is reduced and the power generation performance is excellent.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

<Preparation of catalyst and catalyst composition>
Example 1
Lanthanum sulfate nonahydrate in pure water _{100mL (La 2 (SO 4)} 3 · 9H 2 O) 3g and nitric acid solution _(HNO 3, 60wt% solution) in a solution obtained by mixing 3 mL, cobalt nitrate hexahydrate in pure water 100mL A solution in which 2.4 g of a Japanese product (Co (NO ₃ ) ₂ .6H ₂ O) is dissolved is mixed. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 600 ° C. at a temperature rising rate of 100 ° C./hour in an alumina crucible, and further maintained at 600 ° C. for 1 hour to obtain cobalt oxide-supported lanthanum sulfate.

The obtained cobalt oxide-supported lanthanum sulfate was analyzed by inductively coupled plasma emission spectroscopy (ICP). As a result, the elemental ratio of cobalt element to the total of lanthanum element and sulfur element (Co / La + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into lanthanum sulfate (La ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lanthanum sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 2)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g cesium sulfate octahydrate _{(Ce 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supporting cerium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Ce + S) of cobalt element to the total of cerium element and sulfur element was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) were converted into cesium sulfate (Ce ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supporting cerium sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 3)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfuric acid praseodymium octahydrate _{(Pr 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 A praseodymium sulfate-supported cobalt oxide is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Pr + S) of cobalt element to the total of praseodymium element and sulfur element was 0.4. As a result of composition analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), the particles observed with a transmission electron microscope image (TEM) were converted into praseodymium sulfate (Pr ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, praseodymium sulfate-supported cobalt oxide and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

Example 4
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate neodymium octahydrate _{(Nd 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 A cobalt oxide-supported neodymium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of neodymium element and sulfur element (Co / Nd + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), the particles observed with a transmission electron microscope image (TEM) were converted into neodymium sulfate (Nd ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported neodymium sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 5)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate samarium octahydrate _{(Sm 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supported samarium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Sm + S) of cobalt element to the sum of samarium element and sulfur element was 0.4. Particles observed with a transmission electron microscope image (TEM) were converted into samarium sulfate (Sm ₂ (SO ₄ ) ₃ ) as a result of composition analysis by energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction analysis (XRD). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-carrying samarium sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 6)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfuric acid europium octahydrate _{(Eu 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 A cobalt oxide-supported europium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Eu + S) of cobalt element to the sum of europium element and sulfur element was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) were converted into europium sulfate (Eu ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, europium sulfate-supporting cobalt oxide and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 7)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) , except that was changed to sulfate gadolinium octahydrate _{(Gd 2 (SO 4) 3} · 8H 2 O) 3g 3g to Example 1 A cobalt oxide-supported gadolinium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of gadolinium element and sulfur element (Co / Gd + S) was 0.4. Particles observed with a transmission electron microscope image (TEM) were converted into gadolinium sulfate (Gd ₂ (SO ₄ ) ₃ ) as a result of composition analysis by energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction analysis (XRD). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported gadolinium sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 8)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfuric acid terbium octahydrate _{(Tb 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supporting terbium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of terbium element and sulfur element (Co / Tb + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) were converted into terbium sulfate (Tb ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supporting terbium sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

Example 9
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate dysprosium octahydrate _{(Dy 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 The cobalt oxide-supported dysprosium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Dy + S) of cobalt element to the total of dysprosium element and sulfur element was 0.4. Particles observed with a transmission electron microscope image (TEM) were analyzed by dysprosium sulfate (Dy ₂ (SO ₄ ) ₃ ) as a result of composition analysis by energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction analysis (XRD). It was confirmed that cobalt oxide was supported.

  Next, dysprosium sulfate-supporting cobalt oxide and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 10)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfuric acid holmium octahydrate _{(Ho 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supported holmium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of holmium element and sulfur element (Co / Ho + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) were converted into holmium sulfate (Ho ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported holmium sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 11)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate erbium octahydrate _{(Er 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supported erbium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of erbium element and sulfur element (Co / Er + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into erbium sulfate (Er ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported erbium sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 12)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate thulium octahydrate _{(Tm 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supported thulium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of thulium element and sulfur element (Co / Tm + S) was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into thulium sulfate (Tm ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supporting thulium sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 13)
Example 1 except that 3 g of lanthanum sulfate nonahydrate (La ₂ (SO ₄ ) ₃ .9H ₂ O) was changed to 3 g of ytterbium sulfate octahydrate (Yb ₂ (SO ₄ ) ₃ .8H ₂ O) Cobalt oxide-supported ytterbium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / Yb + S) of cobalt element to the total of ytterbium element and sulfur element was 0.4. Particles observed with a transmission electron microscope image (TEM) were analyzed by ytterbium sulfate (Yb ₂ (SO ₄ ) ₃ ) as a result of composition analysis by energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction analysis (XRD). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported ytterbium sulfate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 14)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfate lutetium octahydrate _{(Lu 2 (SO 4) 3} · 8H 2 O) except for changing the 3g Example 1 Cobalt oxide-supported lutetium sulfate is obtained by the same production method.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of lutetium element and sulfur element (Co / Lu + S) was 0.4. Particles observed with a transmission electron microscope image (TEM) were converted into lutetium sulfate (Lu ₂ (SO ₄ ) ₃ ) as a result of composition analysis by energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffraction analysis (XRD). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lutetium sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 15)
Cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H 2 O) 2.4g of iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 3g and nickel nitrate hexahydrate (Ni _{(NO 3) 2 · 6H 2} O) iron oxide in the same process as in example 1 except for changing the 0.2 g - obtain nickel oxide supported lanthanum sulfate.

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the ratio of the total of iron element and nickel element to the total of lanthanum element and sulfur element (Fe + Ni / La + S) is 0.4, and the element of iron element and nickel element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed by transmission electron microscope image (TEM), iron oxide and nickel oxide are supported on lanthanum sulfate. Confirmed that it has been.

  Next, iron oxide-nickel oxide-supported lanthanum sulfate and Ketjen black (LCP, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 16)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g of lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 2.7g and cesium sulfate octahydrate Cobalt oxide-supported lanthanum-cerium composite sulfate is obtained by the same production method as in Example 1, except that it is changed to (Ce ₂ (SO ₄ ) ₃ · 8H ₂ O) 0.3 g.

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of lanthanum element, cerium element, and sulfur element (Co / La + Ce + S) is 0.4, and the element composition of lanthanum element and cerium element is 0. .9: 0.1. Cobalt oxide is supported on lanthanum-cerium composite sulfate as a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed by transmission electron microscope image (TEM) Confirmed that it has been.

  Next, cobalt oxide-supporting lanthanum-cerium composite sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 17)
Lanthanum sulfate nonahydrate _{(La 2 (SO 4) 3} · 9H 2 O) 3g sulfuric acid praseodymium octahydrate _{(Pr 2 (SO 4) 3} · 8H 2 O) 2.7g sulfate neodymium octahydrate A cobalt oxide-supported praseodymium-neodymium composite sulfate is obtained by the same production method as in Example 1 except that it is changed to (Nd ₂ (SO ₄ ) ₃ · 8H ₂ O) 0.3 g.

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the sum of praseodymium element, neodymium element, and sulfur element (Co / Pr + Nd + S) is 0.4, and the element composition of praseodymium element and neodymium element is 0. .9: 0.1. Cobalt oxide is supported on praseodymium-neodymium composite sulfate as a result of composition analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed by transmission electron microscope image (TEM) Confirmed that it has been.

  Next, cobalt oxide-supported praseodymium-neodymium composite sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 18)
A solution of 1 g of boric acid (H ₃ BO ₃ ) dissolved in 100 mL of pure water is mixed with a solution of 7 g of lanthanum nitrate hexahydrate (La (NO ₃ ) ₃ .6H ₂ O) dissolved in 100 mL of pure water. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 700 ° C. at a heating rate of 100 ° C./hour in an alumina crucible, and further maintained at 700 ° C. for 1 hour to obtain lanthanum borate (LaBO ₃ ).

Boric lanthanum _(LaBO 3) 3.2 g in the dispersion solution in pure water 100mL, a solution of nickel nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H 2 O) 3.8g of pure water 100mL Mix. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 600 ° C. at a temperature rising rate of 100 ° C./hour in an alumina crucible, and further maintained at 600 ° C. for 1 hour to obtain nickel oxide-supported lanthanum borate.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Ni / La + B) of nickel element to the total of lanthanum element and boron element was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), nickel oxide was found in lanthanum borate (LaBO ₃ ). It was confirmed that it was supported.

  Next, nickel oxide-supported lanthanum borate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 19)
Nickel nitrate hexahydrate (Ni (NO ₃ ) ₂ .6H ₂ O) 3.8 g, manganese nitrate hexahydrate (Mn (NO ₃ ) ₂ .6H ₂ O) 3.3 g and cobalt nitrate hexahydrate Manganese oxide-cobalt oxide-supported lanthanum borate is obtained by the same manufacturing method as in Example 18 except that the amount is changed to 0.4 g of (Co (NO ₃ ) ₂ .6H ₂ O).

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the ratio of the total of manganese element and cobalt element to the total of lanthanum element and boron element (Mn + Co / La + B) is 0.4, and the element of manganese element and cobalt element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), manganese oxide and lanthanum borate (LaBO ₃ ) It was confirmed that cobalt oxide was supported.

  Next, manganese oxide-cobalt oxide-supported lanthanum borate and Ketjen Black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 20)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 7g of samarium nitrate hexahydrate _{(Sm (NO 3) 3 ·} 6H 2 O) 6.3g and europium nitrate hexahydrate (Eu obtaining a europium complex borate _{- (NO 3) 3 · 6H} 2 O) except for changing the 0.7g samarium by the same process as in example 18.

Lanthanum borate _(LaBO 3) 3.2 g of samarium - europium complex borate 3.3 g, nickel nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H 2 O) 3.8g of cobalt nitrate 6 hydrate A cobalt oxide-supported samarium-europium composite borate is obtained by the same production method as in Example 18 except that the product is changed to 3.7 g (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the sum of samarium element, europium element and boron element (Co / Sm + Eu + B) is 0.4, and the elemental composition of samarium element and europium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of the particles observed with a transmission electron microscope image (TEM), cobalt oxide is found in samarium-europium complex borate. It was confirmed that it was supported.

  Next, cobalt oxide-supporting samarium-europium complex borate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 21)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 7g gadolinium nitrate pentahydrate _{(Gd (NO 3) 3 ·} 5H 2 O) 6.3g and terbium nitrate hexahydrate (Eu (NO ₃ ) ₃ · 6H ₂ O) A gadolinium-terbium complex borate is obtained by the same production method as in Example 18 except that the amount is changed to 0.7 g.

Lanthanum borate _(LaBO 3) 3.2 g of gadolinium - terbium complex borate 3.5 g, nickel nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H 2 O) 3.8g of cobalt nitrate 6 hydrate A cobalt oxide-supported gadolinium-terbium complex borate is obtained by the same production method as in Example 18 except that the product is changed to 3.7 g (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of gadolinium element, terbium element and boron element (Co / Gd + Tb + B) is 0.4, and the elemental composition of gadolinium element and terbium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of the particles observed with a transmission electron microscope image (TEM), cobalt oxide was found in gadolinium-terbium complex borate. It was confirmed that it was supported.

  Next, cobalt oxide-supported gadolinium-terbium complex borate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 22)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 6g to a solution of pure water 100mL, mixed solution of phosphoric acid _{(H 3} PO 4) 1.6g of pure water 100mL To do. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 700 ° C. at a heating rate of 100 ° C./hour in an alumina crucible, and further maintained at 700 ° C. for 1 hour to obtain lanthanum phosphate (LaPO 4).

Lanthanum phosphate _(LaPO 4) 3.2 g to disperse solution in pure water 100mL, a solution prepared by dissolving iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 4.5g of pure water 100mL Mix. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 700 ° C. at a heating rate of 100 ° C./hour in an alumina crucible, and further maintained at 700 ° C. for 1 hour to obtain iron oxide-supported lanthanum phosphate.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Fe / La + P) of iron to the total of lanthanum and phosphorus was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), iron oxide was found in lanthanum phosphate (LaPO ₄ ). It was confirmed that it was supported.

  Next, iron oxide-supported lanthanum phosphate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 23)
Iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 4.5g of nickel nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H 2 O) 2.9g manganese nitrate hexahydrate Nickel oxide-manganese oxide-supported lanthanum phosphate is obtained by the same manufacturing method as in Example 22 except that it is changed to 0.3 g of (Mn (NO ₃ ) ₂ .6H ₂ O).

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the ratio of the sum of nickel element and manganese element to the sum of lanthanum element and phosphorus element (Ni + Mn / La + P) is 0.4, and the elements of nickel element and manganese element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), nickel oxide and lanthanum phosphate (LaPO ₄ ) It was confirmed that manganese oxide was supported.

  Next, nickel oxide-manganese oxide-supported lanthanum phosphate and Ketjen Black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 24)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 6g of dysprosium nitrate pentahydrate _{(Dy (NO 3) 3 ·} 5H 2 O) 5.4g and holmium nitrate pentahydrate (Ho obtain holmium complex phosphate _{- (NO 3) 3 · 5H} 2 O) except for changing the 0.6g dysprosium in the same process as in example 22.

Lanthanum phosphate _(LaPO 4) 3.2 g of dysprosium - the holmium complex phosphate 3.5 g, iron nitrate nonahydrate _{(Ni (NO 3) 3 ·} 9H 2 O) 4.5g of cobalt nitrate 6 hydrate A cobalt oxide-supported dysprosium-holmium complex phosphate is obtained by the same production method as in Example 22 except that the product is changed to 3.2 g (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of dysprosium element, holmium element and phosphorus element (Co / Dy + Ho + P) is 0.4, and the elemental composition of dysprosium element and holmium element is 0.9: 0.1. As a result of composition analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of the particles observed with a transmission electron microscope image (TEM), cobalt oxide is added to the dysprosium-holmium complex phosphate. It was confirmed that it was supported.

  Next, cobalt oxide-supported dysprosium-holmium complex phosphate and ketjen black (manufactured by Lion, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 25)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 6g of erbium nitrate pentahydrate _{(Er (NO 3) 3 ·} 5H 2 O) 5.4g and thulium nitrate tetrahydrate (Tm An erbium-thulium complex phosphate is obtained by the same production method as in Example 22 except that (NO ₃ ) ₃ · 4H ₂ O) is changed to 0.6 g.

Lanthanum phosphate _(LaPO 4) 3.2 g of erbium - thulium complex in phosphate 3.6 g, iron nitrate nonahydrate _{(Ni (NO 3) 3 ·} 9H 2 O) 4.5g of cobalt nitrate 6 hydrate A cobalt oxide-supported erbium-thulium composite phosphate is obtained by the same production method as in Example 22 except that the product is changed to 3.2 g (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the sum of erbium element, thulium element and phosphorus element (Co / Er + Tm + P) is 0.4, and the elemental composition of erbium element and thulium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), cobalt oxide is added to erbium-thulium complex phosphate. It was confirmed that it was supported.

  Next, cobalt oxide-supporting erbium-thulium complex phosphate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 26)
To a solution of lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 5.7g of pure water 100 mL, ammonium paramolybdate in pure water _{100mL ((NH 4) 6 Mo} 7 O 24 · A solution in which 3.5 g of 4H ₂ O is dissolved is mixed. After heating the mixed solution at 80 ° C. for 4 hours while stirring, the solid component obtained by filtration is dried at 120 ° C. for 4 hours. Thereafter, the solid component is pulverized in a mortar, heated to 600 ° C. at a rate of temperature increase of 100 ° C./hour in an alumina crucible, and further maintained at 600 ° C. for 1 hour to lanthanum molybdate (La ₂ (MoO ₄ ) ₃ ). Get.

Molybdate lanthanum _{(La 2 (MoO 4) 3} ) and 5g of dispersed solution in purified water 100 mL, manganese nitrate hexahydrate in pure water _{100mL (Mn (NO 3) 2} · 6H 2 O) dissolved 3.8g Mix the prepared solution. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 600 ° C. at a temperature rising rate of 100 ° C./hour in an alumina crucible, and further maintained at 600 ° C. for 1 hour to obtain manganese oxide-supported lanthanum molybdate.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio (Mn / La + Mo) of manganese element to the total of lanthanum element and molybdenum element was 0.4. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), lanthanum molybdate (La ₂ (MoO ₄ ) ₃ ) It was confirmed that manganese oxide was supported on the surface.

  Next, manganese oxide-supported lanthanum molybdate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 27)
Manganese nitrate hexahydrate _{(Mn (NO 3) 2 ·} 6H 2 O) 3.8g of cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H 2 O) 3.5g iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) cobalt oxide by the same process as in example 26 except for changing the 0.5 g - obtain iron oxide-supported molybdenum lanthanum.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element and iron element to the total of lanthanum element and molybdenum element (Co + Fe / La + Mo) is 0.4, and elements of cobalt element and iron element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), lanthanum molybdate (La ₂ (MoO ₄ ) ₃ ) It was confirmed that cobalt oxide and iron oxide were supported on the surface.

  Next, cobalt oxide-iron oxide-supported lanthanum molybdate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 28)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 5.7g a ytterbium nitrate trihydrate _{(Yb (NO 3) 3 ·} 3H 2 O) 4.9g nitrate lutetium trihydrate An ytterbium-lutetium complex molybdate is obtained by the same production method as in Example 26 except that the amount is changed to 0.6 (Lu (NO ₃ ) ₃ .3H ₂ O).

5 g of lanthanum molybdate (La ₂ (MoO ₄ ) ₃ ) is added to 5.5 g of ytterbium-lutetium complex molybdate, and 3.8 g of manganese nitrate hexahydrate (Mn (NO ₃ ) ₂ .6H ₂ O) is added to cobalt nitrate. A cobalt oxide-supported ytterbium-lutetium composite molybdate is obtained in the same manner as in Example 26 except that the amount is changed to 3.9 g of hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of ytterbium element, lutetium element and molybdenum element (Co / Yb + Lu + Mo) is 0.4, and the elemental composition of ytterbium element and lutetium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of the particles observed by transmission electron microscope image (TEM), cobalt oxide is added to ytterbium-lutetium complex molybdate. It was confirmed that it was supported.

  Next, cobalt oxide-supported ytterbium-lutetium composite molybdate and ketjen black (manufactured by Lion, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 29)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 5.7g a terbium nitrate hexahydrate _{(Tb (NO 3) 3 ·} 6H 2 O) 5.4g and praseodymium nitrate hexahydrate A terbium-praseodymium complex molybdate is obtained by the same production method as in Example 26 except that the amount is changed to 0.6 (Pr (NO ₃ ) ₃ .6H ₂ O).

5 g of lanthanum molybdate (La ₂ (MoO ₄ ) ₃ ) is added to 5.3 g of ytterbium-lutetium complex molybdate, and 3.8 g of manganese nitrate hexahydrate (Mn (NO ₃ ) ₂ .6H ₂ O) is added to cobalt nitrate. A cobalt oxide-supported terbium-praseodymium composite molybdate is obtained by the same production method as in Example 26 except that the amount is changed to 3.8 g of hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O).

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of terbium element, praseodymium element and molybdenum element (Co / Tb + Pr + Mo) is 0.4, and the elemental composition of terbium element and praseodymium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of the particles observed with a transmission electron microscope image (TEM), cobalt oxide was added to terbium-praseodymium composite molybdate. It was confirmed that it was supported.

  Next, cobalt oxide-supporting terbium-praseodymium composite molybdate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 30)
To a solution of lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 4.2g of pure water 100mL, pure water 100mL Ammonium metatungstate _{((NH 4) 6 [H} 2 W 12 (O ₄₀ ] · 6H ₂ O) A solution in which 3.8 g is dissolved is mixed. The mixed solution is heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component is dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 900 ° C. at a temperature rising rate of 100 ° C./hour in an alumina crucible, and further maintained at 900 ° C. for 1 hour, whereby lanthanum tungstate (La ₂ (WO ₄ ) ₃ ) Get.

Tungstate lanthanum _{(La 2 (WO 4) 3} ) and 5g of dispersed solution in purified water 100 mL, iron nitrate nonahydrate in pure water _{100mL (Fe (NO 3) 3} · 9H 2 O) 3.6g nitrate A solution in which 0.3 g of manganese hexahydrate (Mn (NO ₃ ) ₂ .6H ₂ O) was dissolved was mixed. The mixed solution was heated to 100 ° C. with stirring to remove the water solvent, and the obtained solid component was dried at 120 ° C. for 12 hours. Thereafter, the solid component is pulverized in a mortar, heated to 600 ° C. at a rate of temperature increase of 100 ° C./hour in an alumina crucible, and further maintained at 700 ° C. for 1 hour, whereby iron oxide-manganese oxide-supported lanthanum tungstate is obtained. obtain.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the ratio of the total of iron element and manganese element to the total of lanthanum element and tungsten element (Fe + Mn / La + W) is 0.4, and the element of iron element and manganese element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), lanthanum tungstate (La ₂ (WO ₄ ) ₃ ) It was confirmed that iron oxide and manganese oxide were supported on the surface.

  Next, iron oxide-manganese oxide-supported lanthanum tungstate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 31)
Iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 3.6g manganese nitrate hexahydrate _{(Mn (NO 3) 2 ·} 6H 2 O) 0.3g of cobalt nitrate hexahydrate The same production method as in Example 30 except that 2.6 g of (Co (NO ₃ ) ₂ .6H ₂ O) and 0.3 g of nickel nitrate hexahydrate (Ni (NO ₃ ) ₂ .6H ₂ O) were changed. To obtain cobalt oxide-nickel oxide-supported lanthanum tungstate.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of the total of cobalt element and nickel element to the total of lanthanum element and tungsten element (Co + Ni / La + W) is 0.4, and the element of cobalt element and nickel element The composition was 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), lanthanum tungstate (La ₂ (WO ₄ ) ₃ ) It was confirmed that cobalt oxide and nickel oxide were supported on the surface.

  Next, cobalt oxide-nickel oxide-supported lanthanum tungstate and Ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 32)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 4.2g neodymium nitrate hexahydrate _{(Nd (NO 3) 3 ·} 6H 2 O) 3.8g and samarium nitrate hexahydrate A neodymium-samarium composite tungstate is obtained by the same production method as in Example 30, except that it is changed to 0.4 g of (Sm (NO ₃ ) ₃ · 6H ₂ O).

Tungstate lanthanum _{(La 2 (WO 4) 3} ) 5g neodymium - samarium composite tungstate 5g, iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 3.6g manganese nitrate hexahydrate dihydrate _{(Mn (NO 3) 2 ·} 6H 2 O) 0.3g cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H 2 O) was changed to 2.8g similar to example 30 A cobalt oxide-supported neodymium-samarium composite tungstate is obtained by the production method.

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the total of neodymium element, samarium element and tungsten element (Co / Nd + Sm + W) is 0.4, and the elemental composition of neodymium element and samarium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), cobalt oxide is added to neodymium-samarium composite tungstate. It was confirmed that it was supported.

  Next, cobalt oxide-supported neodymium-samarium complex tungstate and ketjen black (manufactured by Lion, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 33)
Lanthanum nitrate hexahydrate _{(La (NO 3) 3 ·} 6H 2 O) 4.2g a europium nitrate hexahydrate _{(Eu (NO 3) 3 ·} 6H 2 O) 3.8g and gadolinium nitrate pentahydrate Europium-gadolinium complex tungstate is obtained by the same production method as in Example 30 except that it is changed to 0.4 g of (Gd (NO ₃ ) ₃ .5H ₂ O).

Tungstate lanthanum _{(La 2 (WO 4) 3} ) 5g europium - gadolinium complex tungstate 5g, iron nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 3.6g manganese nitrate hexahydrate dihydrate _{(Mn (NO 3) 2 ·} 6H 2 O) 0.3g of cobalt nitrate hexahydrate _{(Co (NO 3) 2 ·} 6H 2 O) was changed to 2.8g similar to example 30 A cobalt oxide-supported europium-gadolinium composite tungstate is obtained by the production method.

  As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio of cobalt element to the sum of europium element, gadolinium element and tungsten element (Co / Eu + Gd + W) is 0.4, and the elemental composition of europium element and gadolinium element is 0.9: 0.1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD) of particles observed with a transmission electron microscope image (TEM), cobalt oxide is present in europium-gadolinium composite tungstate. It was confirmed that it was supported.

  Next, cobalt oxide-supported europium-gadolinium composite tungstate and ketjen black (manufactured by Lion, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 34)
Cobalt oxide-supported lanthanum sulfate is obtained by the same production method as in Example 1 except that 2.4 g of cobalt nitrate hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O) is changed to 12 g.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / La + S) of cobalt element to the total of lanthanum element and sulfur element was 2. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into lanthanum sulfate (La ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lanthanum sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 35)
Cobalt oxide-supported lanthanum sulfate is obtained by the same production method as in Example 1 except that 2.4 g of cobalt nitrate hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O) is changed to 6 g.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio (Co / La + S) of cobalt element to the total of lanthanum element and sulfur element was 1. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into lanthanum sulfate (La ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lanthanum sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 36)
Cobalt oxide-supported lanthanum sulfate is obtained by the same production method as in Example 1 except that 2.4 g of cobalt nitrate hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O) is changed to 1.2 g.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the elemental ratio of cobalt element to the total of lanthanum element and sulfur element (Co / La + S) was 0.2. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into lanthanum sulfate (La ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lanthanum sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 37)
Cobalt oxide-supported lanthanum sulfate is obtained by the same production method as in Example 1 except that 2.4 g of cobalt nitrate hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O) is changed to 0.06 g.

As a result of analysis by inductively coupled plasma emission spectroscopy (ICP), the element ratio (Co / La + S) of cobalt element to the total of lanthanum element and sulfur element was 0.01. As a result of compositional analysis by energy dispersive X-ray spectroscopic analysis (EDS) and powder X-ray diffraction analysis (XRD), particles observed with a transmission electron microscope image (TEM) are converted into lanthanum sulfate (La ₂ (SO ₄ ) ₃ ). It was confirmed that cobalt oxide was supported.

  Next, cobalt oxide-supported lanthanum sulfate and ketjen black (manufactured by Lion Corporation, ECP) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

(Example 38)
2.7 g of ketjen black (manufactured by Lion Corporation, ECP) was dispersed in 1000 mL of pure water set at 80 ° C., and 100 mL of a chloroplatinic acid aqueous solution (corresponding to 0.3 g in terms of Pt) was mixed therewith, and then 5 wt% An aqueous sodium hydrogen carbonate solution is added dropwise at a rate of 2 mL / min to adjust the pH of the solution to 7 to 8, and then stirring is continued for 1 hour. Next, the reaction solution is filtered, and the resulting solid product is dispersed in the order of 1000 mL of a 0.3 wt% sulfuric acid aqueous solution and 1000 mL of pure water, and boiled and washed with each solution for 30 minutes. The washing solution is filtered to recover the solid product, and then dried in air at 100 ° C. overnight. The resulting solid product is pulverized and subjected to a reduction treatment at 400 ° C. for 1 hour in a 100% hydrogen gas stream to obtain supported carbon (Pt / C: Pt supported amount 10 wt%) with Pt. The amount of Pt supported on carbon was determined by performing analysis by inductively coupled plasma emission spectroscopy (ICP).

  The cobalt oxide-supported lanthanum sulfate of Example 1 and the Pt / C (Pt support amount of 10 wt%) are weighed at a weight ratio of 1: 1 and mixed in a mortar to obtain a catalyst composition.

<Production of cathode>
1 g of the catalyst composition obtained in Examples 1 to 38, 4 g of a 5 wt% Nafion solution (registered trademark by DuPont), 4 g of 1-propanol and 4 g of water are placed in a pot containing zirconia balls, and dispersion by a ball mill is performed. Perform for a while to produce a catalyst slurry.

  For the diffusion layer, carbon paper having a conductive porous layer made of carbon and PTFE (polytetrafluoroethylene) (manufactured by Toray, TGP-H-060, thickness 180 μm) is used. The conductive porous layer has a thickness of 5 μm, and the weight ratio of carbon and PTFE is 40:60.

Using an applicator, the catalyst slurry is applied to the surface of the conductive porous layer so as to have a uniform thickness. The coating thickness is adjusted so that the catalyst composition is 20 mg / cm ² in the diffusion layer. Further, it is dried at 100 ° C.

(Example 39)
The catalyst slurry prepared using the Pt-supported carbon (Pt / C) obtained in Example 38 is applied to the surface of the conductive porous layer using an applicator so as to have a uniform thickness. The coating thickness is adjusted so that the catalyst composition is 1 mg / cm ² in the diffusion layer. Further, it is dried at 100 ° C.

Next, the catalyst slurry prepared using the catalyst composition obtained in Example 1 is applied to the surface of Pt / C so as to have a uniform thickness using an applicator. Note that water is sprayed on the Pt / C surface in advance in order to suppress combustion with the catalyst slurry. In the diffusion layer, the coating thickness is adjusted so that the catalyst composition is 20 mg / cm ² . Further, it is dried at 100 ° C.

(Example 40)
The catalyst slurry prepared using the catalyst composition obtained in Example 1 is applied to the surface of the conductive porous layer using an applicator so as to have a uniform thickness. The coating thickness is adjusted so that the catalyst composition is 20 mg / cm ² in the diffusion layer. Further, it is dried at 100 ° C.

Next, the catalyst slurry produced using the Pt-supported carbon (Pt / C) obtained in Example 38 is made to have a uniform thickness on the surface of the catalyst composition obtained in Example 1 using an applicator. Apply. In the diffusion layer, the coating thickness is adjusted so that the catalyst composition is 1 mg / cm ² . Further, it is dried at 100 ° C.

(Comparative Example 1)
The catalyst slurry prepared using the Pt-supported carbon (Pt / C) obtained in Example 38 is applied to the surface of the conductive porous layer using an applicator so as to have a uniform thickness. The coating thickness is adjusted so that the catalyst composition is 1 mg / cm ² in the diffusion layer. Further, it is dried at 100 ° C.

<Production of anode>
Pt-supported carbon (Pt / C) obtained in Example 38: Pt-supported amount 10 wt%, 5 wt% Nafion solution (registered trademark manufactured by DuPont) 4 g, 1-propanol 4 g, and water 4 g in a pot containing zirconia balls And dispersion by a ball mill for 6 hours to produce a catalyst slurry.

  For the diffusion layer, carbon paper having a conductive porous layer made of carbon and PTFE (manufactured by Toray, TGP-H-060, thickness 180 μm) is used. The conductive porous layer has a thickness of 5 μm, and the weight ratio of carbon and PTFE is 40:60.

Using an applicator, the catalyst slurry is applied to the surface of the conductive porous layer so as to have a uniform thickness. The coating thickness is adjusted so that Pt / C is 1 mg / cm ² in the diffusion layer. Further, it is dried at 100 ° C.

<Preparation of membrane electrode assembly>
Each of the cathode and anode of Examples 1 to 40 and Comparative Example 1 was cut out so that the electrode area was 12 cm ^2, and Nafion 212 (trade name: manufactured by DuPont) was sandwiched between the cathode and the anode as a polymer electrolyte membrane. A membrane electrode assembly is manufactured by thermocompression bonding at 125 ° C. for 10 minutes at a pressure of 30 kg / cm ² .

  Next, the oxygen reduction activity of the cathode of the membrane electrode assembly obtained in Examples 1 to 40 is evaluated by the following method.

  The membrane electrode assemblies obtained in Examples 1 to 40 and Comparative Example 1 were internally contained in a cathode holder 9 with an oxidant gas supply groove 8 and an anode holder 11 with a fuel supply groove 10 as shown in FIG. A single cell is built in to produce electricity.

  In the power generation test, the temperature of the membrane electrode assembly is externally controlled with a heater so as to set the temperature constant, and hydrogen gas and oxygen gas humidified by a humidifier are supplied to the membrane electrode assembly. The membrane electrode assembly and the electronic load device were connected between the terminals by wiring, and the change in voltage when the current (load) was changed was measured. The measurement conditions for the power generation test are as follows.

80 ℃
Pressure: Atmospheric pressure Anode: Hydrogen (200 mL / min · cm ² ), 95% humidification Cathode: Oxygen (400 mL / min · cm ² ), 95% humidification Electronic load device: PLZ70UA manufactured by Kikusui Electronics Co., Ltd.
As an index of the oxygen reduction activity of the cathode catalyst, the current value per mass of the catalyst at a predetermined potential (0.9 V), that is, the mass activity ( A / mg).

  Next, a potential cycle test is performed as a deterioration durability test of the catalyst composition.

  In the potential cycle test, the temperature of the membrane electrode assembly is controlled by a heater from the outside so as to set the temperature constant, and hydrogen gas and nitrogen gas humidified by a humidifier are supplied to the membrane electrode assembly. The membrane electrode assembly and the electrochemical evaluation system are connected between terminals by wiring. In order to perform a deterioration durability test of the cathode, the cathode is set as a working electrode, the anode as a counter electrode and a reference electrode, and the cathode potential is set so as to cycle a potential range in which the cathode deterioration is accelerated. The degree of deterioration can be evaluated by measuring the mass activity before and after the potential cycle. The measurement conditions for the potential cycle test are as follows.

80 ℃
Pressure: Atmospheric pressure Potential range: 0.9V (30 seconds hold) ⇔ 1.3V (30 seconds hold)
* The time required for one cycle is 1 minute. Anode: Hydrogen (200 mL / min · cm ² ), 95% humidification Cathode: Nitrogen (200 mL / min · cm ² ), 95% humidification Number of cycles: 10,000 times Electrochemical measurement system: Hokuto Made by Denko, Hz-5000
The obtained results are shown in Tables 1 to 4 as mass activity at the initial stage of power generation (P0), mass activity after potential cycle (P), and mass activity maintenance rate (P / P0:%).

As shown in Tables 1 to 4, the catalyst of this embodiment and the catalyst composition all have higher mass activity at the initial stage of power generation than Comparative Example 1.

  Also, in the catalyst deterioration acceleration test by the potential cycle, the mass activity retention rate is higher than that of Comparative Example 1.

  And when it uses for the membrane electrode assembly using these catalyst compositions, and also a fuel cell, electric power generation performance and also durability improve further.

  This embodiment is presented as an example and is not intended to limit the scope of the invention. The present embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 Polymer electrolyte membrane 2 Fuel electrode (anode)
3 Air electrode (cathode)
4, 6 Diffusion layer 5 Anode catalyst layer 7 Cathode catalyst layer 8 Oxidant gas supply groove 9 Cathode holder 10 Fuel supply groove 11 Anode holder 12 Membrane electrode assembly (MEA)
20 Fuel cell

Claims (5)

A catalyst composition containing the catalyst according to any of the following (A) or (B) and a conductive material;
With polyelectrolytes
A cathode catalyst layer comprising:
(A) a rare earth oxoacid salt carrier containing at least one element L selected from rare earth elements and at least one element X selected from the group consisting of B, P, Mo, W and S; It is a composite containing oxide particles which are supported on the surface of the rare earth oxoacid salt support and contain at least one element M selected from the group consisting of Mn, Fe, Co and Ni. And a catalyst.
(B) The composite is characterized in that an element ratio (M / (L + X)) of the element L to the element M with respect to the element L is in a range of 0.01 to 2 (mol ratio). Catalyst. A catalyst composition containing the catalyst according to any one of (C) and (D) below, and an oxygen reduction catalyst in which noble metal particles and / or noble metal alloy particles are supported on a conductive material;
With polyelectrolytes
A cathode catalyst layer comprising:
(C) a rare earth oxoacid salt carrier containing at least one element L selected from rare earth elements and at least one element X selected from the group consisting of B, P, Mo, W and S; It is a composite containing oxide particles which are supported on the surface of the rare earth oxoacid salt support and contain at least one element M selected from the group consisting of Mn, Fe, Co and Ni. And a catalyst.
(D) The composite is characterized in that an element ratio (M / (L + X)) between the element L and the element M with respect to the element X is in a range of 0.01 to 2 (mol ratio). Catalyst. The cathode catalyst layer is at least claim 1 or 2, the catalyst layer on the conductive material comprising a noble metal particles and / or oxygen reduction catalyst and the polymer electrolyte and the noble metal alloy particles are supported, characterized in that the formed by stacking The cathode catalyst layer described in 1. A membrane electrode assembly, wherein the cathode catalyst layer according to any one of claims 1 to 3 is used. A fuel cell comprising the membrane electrode assembly according to claim 4 .

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