JP6059918B2 - Method for manufacturing fuel cell electrode material - Google Patents

Description

The present invention water-absorbing performance, have a hydrogen storage performance, a method of manufacturing of an electrode material of high fuel cell of the electrode of the fuel cell.

Iron (Fe) ions are usually divalent (Fe ²⁺ ) among oxides, as seen in red rust hematite (Fe ₂ ³⁺ O ₃ ) and magnetite (Fe ²⁺ Fe ³⁺ O ₄ ). Or a trivalent (Fe ³⁺ ) ion state. However, it is disclosed in Prior Art Document 1 shown below that an oxide containing an iron ion in a high oxidation state called “abnormal valence” includes unique functional characteristics on electronics.

Kyoto University homepage: Elucidation of functional characteristic principles of abnormal valence iron ions

The prior art document 1 discloses higher-order iron oxides LaCu ₃ Fe ₄ O _{12 and the} like, and only discloses that these iron oxides can be used for switch sensors or the like. There is no description about things. The inventor has discovered various special functions of a compound of an alkali metal and a transition metal oxide.

Therefore, the method for producing an electrode material for a fuel cell according to the present invention includes placing a stainless steel material or an iron material and a reactant in an oxygen-free atmosphere free from oxygen in the air, and heating the atmosphere to produce fine particles of the reactant. allowed scattered within, and to form an oxide of higher order high oxygen number to the stainless steel or iron surface by supplying steam into the atmosphere.

  The stainless material is austenitic stainless steel containing nickel, and the reactant is preferably sodium hydroxide (NaOH) or potassium hydroxide (KOH).

  Furthermore, it is preferable to heat the oxygen-free atmosphere to 500 to 700 ° C. or higher.

  Furthermore, it is preferable that the oxygen-free atmosphere is formed as a thin film while being maintained at a pressure lower than 1 atm while being sucked with a vacuum pump.

When NaOH or KOH is heated above its melting point, nano-order fine particles are scattered from the liquid surface to an oxygen-free atmosphere in the air, and in a state where the supplied water vapor molecules are captured, a stainless element atmosphere (Cr-Ni -Fe), the higher order of the number of oxygen such as Na ₃ Fe ₅ O ₉ , K ₃ Fe ₅ O ₉ , Na _x Fe _y Cr _z O _w (x, y, z and w are integers) An alkali metal-transition metal oxide film is formed, and this film is electrically conductive, hydrophilic, high in hardness, magnetic, heat resistant, does not melt even at 1000 ° C., has a high hydrogen storage capacity, and converts hydrogen into hydrogen ions. (H ⁺ ) and electron (e ⁻ ) can be separated, and can be used as an electrode (negative electrode) of a fuel cell. Further, when the alkali metal-transition metal oxide is formed on the stainless steel surface, a nuclear reaction occurs. Increase the likelihood that it will occur.

  The stainless material is preferably an austenitic stainless steel containing Ni that acts as a catalyst when producing higher-order oxides. The alkali metal supply reactant is an easily available and inexpensive NaOH or KOH. Preferably, the heating temperature of the atmosphere may be higher than the melting point (308 ° C., 316 ° C.) of NaOH and KOH, but preferably 500 to 700 ° C. where the reactivity is high, and if the oxide film is always formed under reduced pressure, Since an oxide film can be formed while discharging unnecessary reaction products during the reaction to the outside of the system, a highly purified oxide film can be formed.

It is explanatory drawing of the production | generation method of the higher-order alkali metal-transition metal oxide film of this invention. It is a production | generation state explanatory drawing of an alkali metal-transition metal oxide film. It is a crushing state explanatory drawing of an alkali metal-transition metal oxide film. It is use condition explanatory drawing as a hygroscopic material. It is use condition explanatory drawing as a hydrogen storage material. It is explanatory drawing of the use condition as an electrode plate of a fuel cell. It is function explanatory drawing at the time of a nuclear reaction.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

In FIG. 1, an apparatus M for producing a high-order alkali metal-transition metal oxide film (hereinafter referred to as an oxide film) having a large number of oxygen has a cylindrical reaction cell 1 in which a reactant 2 is contained. The surrounding of the reaction cell 1 is heated by a mantle heater 3. On the upper surface of the reaction cell 1, a water pipe 4 for supplying water or water vapor and a hydrogen pipe 5 for discharging hydrogen generated by the reaction are provided, and a vacuum pump 6 is provided in the hydrogen pipe 5. The air (oxygen) in the reaction cell 1 is exhausted by the vacuum pump 6.

  The reaction cell is made of stainless steel or iron, and is preferably austenitic stainless steel containing nickel (Ni), and SUS304 (Cr18% -Ni8% -residual Fe) is preferred. This is because nickel (Ni) plays a catalytic action during the reaction and increases the reactivity.

The reactant is preferably an alkali metal hydroxide (for example, sodium hydroxide (NaOH) or potassium hydroxide (KOH)). When these reactants are heated to the melting point or higher (300 to 350 ° C.), From the liquid surface, the nano-order fine particles 7 scatter into the reaction cell 1. Further, as the reactant, an alkali metal-transition metal oxide such as solid potassium titanate (K _{2) is used.} TiO ₃ ), sodium titanate (Na ₂ TiO ₃ ), potassium chromate (K ₂ Cr ₂ O ₇ ) and the like may be used.

  Although the alkali metal hydroxide can increase the density of scattered fine particles as a molten salt, the alkali metal-transition metal oxide has a high melting point and does not produce a molten salt at 700 ° C. or lower. In order to disperse countless fine particles in the case of a solid reactant, it is preferable to heat to a temperature of 500 to 600 ° C. In the case of the alkali metal hydroxide, it is preferable to heat to this temperature. If it is desired to form the oxide film on the surface of the electrode plate, an electrode plate (SUS304) 8 is installed in the reaction cell 1.

When the apparatus M is operated, the vacuum pump 6 is operated to discharge air (oxygen) from the reaction cell 1 and the mantle heater 3 is operated to heat the atmosphere in the reaction cell 1 to 500 to 700 ° C. At this time, when an alkali hydroxide is used as the reactant, it becomes a molten salt, and the fine particles 7 scatter from the liquid surface into the reaction cell 1. Further, when an alkali metal-transition metal oxide such as K ₂ TiO ₃ is used, fine particles are scattered from the surface while being fixed. When water or water vapor is supplied into the reaction cell 1 in this state, since the fine particles are hydrophilic, water vapor molecules are captured and act on the inner wall of the reaction cell 1 to form a higher-order alkali metal-transition metal oxide film. This reaction may be carried out under a pressure lower than 1 atm, that is, a so-called reduced pressure by always operating the vacuum pump 6, or may be supplied with water vapor at normal pressure after initially discharging the air. When the reaction is continued under reduced pressure, reaction impure products are easily discharged, so that an oxide film with few impurities can be obtained.

Specifically, for example, when NaOH is used as a reactant, Fe is present on the inner wall of the iron material or stainless steel, and when steam is supplied thereto,
H ₂ O + Fe → FeO + 1 / 2H ₂ (1)
The reaction yields FeO,
FeO + NaOH (fine particles) → NaFeO ₂ + 1 / 2H ₂ (2)
Furthermore, this NaFeO ₂ reacts with water vapor and iron (Fe),
3NaFeO ₂ + 2Fe + 3H ₂ O → Na ₃ Fe ₅ O ₉ + 3H ₂ (3)
A higher order alkali metal-iron oxide 9 is produced. At this time, alkali metal-iron oxides such as Na ₃ Fe ₅ O ₈ , Na ₄ Fe ₆ O ₁₁ , and Na ₅ FeO ₄ are generated due to the difference in oxygen partial pressure.

In this case, in the case of a stainless steel, Ni is a catalyst and does not form an oxide, but Cr is added to Na ₃ Fe ₅ O ₉ to form Na _x Fe _y Cr _z O _w (x, y, z, w). Is an integer) alkali metal-transition metal (Fe, Cr) oxide.

This alkali metal-transition metal oxide (Fe alone, both Fe and Cr) has extremely strong water absorption, absorbs water when left in the air, has conductivity and magnetism, and has a remarkable hydrogen storage capacity. high. It is extremely hard and is brittle with a Mohs hardness of 6 or more. Further, it has a function similar to that of palladium (Pd), and has a function of separating a hydrogen atom (H) into a hydrogen ion (H ⁺ ) and an electron (e ⁻ ). Further, when nano-order fine particles of the reactant adhere to the oxide film and hydrogen or deuterium (containing 1/7000 in water) is sucked into the fine particles, a nuclear reaction is likely to occur.

Even when TiO ₂ is used as a reactant, the fine particles act on the iron or stainless steel surface to form an oxide film of Na _x Ti _y Fe _z O _w and Na _x Ti _y Cr _z O _w .

When these films l are reacted for a long time, they are formed in multiple layers on the iron or stainless steel surface as shown in FIG. 2, and when the first oxide film 11 formed _first has a predetermined thickness, it peels off from the inner wall, When the new inner wall surface is exposed, the second oxide layer l ₂ of the following, further the second oxide layer l ₂ is peeled off the third oxide film l ₃ of the following will be formed. Fine particles scatter from the surface of the oxide film l (l ₁ , l ₂ , l ₃ ) at 500 to 700 ° C., and the reactivity between the fine particles and water vapor is extremely high.

Next, the use of the oxide film will be described.
1. Hygroscopic material Since the oxide film 1 contains an alkali metal, the hygroscopic property (hydrophilicity) is high, and the fine particles scattered from the high temperature (500 to 700 ° C.) have high water vapor capturing ability and reactivity. Although it is high, the hygroscopicity is remarkably high even at room temperature, and there is a use as a desiccant. Its moisture absorption is 30% or more, which is higher than that of silica gel.

That is, first, the oxide film l (l ₁ , l ₂ , l ₃ ) is peeled off from the metal surface (Fe, SUS304) and driven up and down with the crushing table 31 provided in the vacuum vessel 30 as shown in FIG. The oxide film l is crushed by the crushing piston 32 to be granulated, and is put in a mesh bag 40 and used as shown in FIG.
2. Hydrogen storage material The oxide film 1 has extremely high hydrogen storage properties and is light, so that the storage rate exceeds 2% and can be manufactured at low cost. Occluded at about 500 ° C., once returned to room temperature, expelled hydrogen occluded at 100-200 ° C. Further, even at room temperature, if the pressure is set to several atmospheres or more, a large amount of hydrogen is occluded.

As a specific device, as shown in FIG. 5, the hydrogen storage device 50 includes a pressure vessel 51, and a plurality of shelves 52, 52... 52 are provided in the pressure vessel 51. On the lower side of the shelf 52, heaters 54, 54... 54 as heating devices are provided, and hydrogen (H ₂ ) is predetermined by a pump 55. The pressure is supplied into the pressure vessel 51, and is generally occluded at a few atmospheres at room temperature, and the occluded hydrogen is released by heating to about 200 ° C. by the heater 54.
3. Fuel Cell Electrode Material The oxide film 1 has a function of separating hydrogen ions (H ⁺ ) and electrons (e ⁻ ) in the same manner as palladium (Pd), and can therefore be used as a fuel cell electrode. . FIG. 6 shows a fuel cell 60. In the fuel cell 60, one of the electrode plates 8 on which the oxide film 1 is formed as shown in FIG. 1 is a negative electrode 8 ⁻ , the other is a positive electrode 8 ⁺ , and an electrolyte therebetween. The membrane 61 is sandwiched, and the electrolyte membrane 61 is made of, for example, a solidified silicon carbide powder holding a concentrated phosphoric acid solution. Hydrogen gas (H ₂ ) is supplied to the negative electrode 8 ⁻ side. At the same time, residual gas is discharged from the top. On the other hand, oxygen O ₂ is supplied to the positive electrode 8 ⁺ side and discharged as water. In this way, the load 62 operates.
4). Nuclear Reaction Inducing Material Various experiments have been conducted in this regard, and it is considered that the oxide film induces a nuclear reaction when these experiments are combined. The grounds are as follows.

1) The chemical reaction formulas (1), (2) and (3) are summarized as follows:
_{3Fe + 2NaOH + NaFeO 2 + FeO} + 4H 2 O
→ Na ₃ Fe ₅ O ₉ + 5H ₂ (4)
Thus, 1.25 times as much hydrogen is generated with respect to 1 mol of water, but more hydrogen than this logical value is generated. That is, hydrogen more than 1.5 times the injected water is generated.

  2) Neutrons and γ rays are detected during the reaction.

  3) During the reaction, elements (for example, Al, Zn) that are not present before the reaction are detected on the inner wall of the reaction cell 1.

4) When K ₂ TiO ₃ is placed in the reaction cell 1 and heated to 400 to 600 ° C., hydrogen and gases of mass 16 and 27 are detected by the mass analyzer without injecting water. An oxygen gas with a mass of 32 is not detected.

  5) During the reaction of the apparatus M in FIG. 1, the temperature in the hydrogen pipe 5 is instantaneously lowered by 200 ° C. or more, and a reaction that cannot occur in a normal chemical reaction occurs.

Judging from these facts, the oxide has a function of inducing a nuclear reaction, and even when K ₂ TiO ₃ is used as a reactant without water, an element gas having a mass number smaller than that of oxygen (O ₂ ). Occurs. Therefore, it is considered that fission of any element in the compound of K _x Ti _y Fe _z O _w has occurred. By analogy with the fact that oxygen gas is not generated and gas with a smaller mass (including hydrogen and nitrogen) is generated, a small amount of oxygen atoms are fissioned into various gases. It seems to be. The trigger is that hydrogen ions (H ⁺ ) and oxygen atoms are taken into the high-temperature oxide film, and these hydrogen ions (H ⁺ ) act on the nuclei of the oxygen atoms, causing fission with the tunnel effect. Seem. Since the binding energy of oxygen is the smallest among the elements of the oxide film, the splitting of oxygen nuclei is likely to occur.

That is, as shown in FIG. 7, when NaOH particles capturing water vapor come into contact with the oxide film 1 formed on the inner wall of the reaction cell 1, the water is ionized to generate hydrogen ions (H ⁺ ) and oxygen atoms (O). It separates into electrons (e ⁻ ) and occludes hydrogen ions (H ⁺ ) in the film, oxygen combines with other elements to form a compound, and electrons (e ⁻ ) have no special outflow circuit in the film. And stay in the stainless steel. The hydrogen ions (H ⁺ ) in the film increase as the reaction progresses, and some of them act on oxygen nuclei to cause fission, and some of them move to the nearby electrons (e ^- ) To form hydrogen gas (H ₂ ). In particular, the reaction in the hydrogen pipe 5 in FIG. 1 is active because an oxide film is also formed in the hydrogen pipe 5 and the concentration of the NaOH fine particles capturing water vapor is significantly higher than in other places. .

The electrode material of the fuel cell is applicable fuel cell industry, automotive industry, the energy industry.

DESCRIPTION OF SYMBOLS 1 ... Reaction cell 2 ... Reactant 3 ... Mantle heater 6 ... Vacuum pump l ... Oxide film

Claims (4)

A reactive agent made of stainless steel or iron and sodium hydroxide or potassium hydroxide is installed in an oxygen-free atmosphere free from oxygen in the air, and the atmosphere is heated to disperse the fine particles of the reactant into the atmosphere. A method for producing an electrode material for a fuel cell, wherein water vapor is supplied into the atmosphere to form an oxide film on the surface of the stainless steel or iron material. 2. The oxide film according to claim 1, wherein the oxide film is at least one of Na ₃ Fe ₅ O ₇ , K ₃ Fe ₅ O ₉ , and Na _x Fe _y Cr _z O _w (where x, y, z, and w are integers). Manufacturing method of electrode material of fuel cell . The method for producing an electrode material for a fuel cell according to claim 1 or 2, wherein the inside of the oxygen-free atmosphere is heated to 500 to 700 ° C or higher. 4. The method for producing an electrode material for a fuel cell according to claim 1, wherein the oxygen-free atmosphere is formed as a thin film while being maintained at a pressure lower than 1 atm while being sucked by a vacuum pump.

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