JP2005251427A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable continuous operation of a fuel cell device by simplifying supplement and exchange of its fuel, and to enhance convenience of the fuel cell device. <P>SOLUTION: This fuel cell device is equipped with a storage vessel 1 to store hydrocarbon, a decomposition reactor 2 provided with a catalyst having activity to the decomposing reaction of the hydrocarbon, an oxidation reactor 7 provided with a catalyst having activity to the oxidizing reaction of hydrocarbon or hydrogen, and a fuel cell 9. At least either the storage vessel 1 or the decomposition reactor 2 is reversibly separated from or combined with the fuel cell device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell device including a container for decomposing hydrocarbons into hydrogen and carbon using a catalyst.

  A fuel cell is an electrochemical device that obtains electric power by electrochemically reacting hydrogen at an anode and oxygen at a cathode. Reactions represented by the formula (1) are performed at the anode and the formula (2) is performed at the cathode. In a fuel cell, electric energy can be extracted directly from hydrogen as a fuel. In other words, since the fuel cell is not subject to the Carnot cycle, the power generation efficiency of the cell is high. In addition to high power generation efficiency, fuel cells are characterized by high output density and no emissions containing carbon dioxide or nitrogen oxides. Yes.

2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
In recent years, the progress of portable electronic devices such as mobile phones, mobile computers and PDAs has been remarkable. With the advancement of these portable electronic devices, power sources with higher energy density are required. Until now, secondary batteries such as nickel metal hydride batteries and lithium ion batteries have been mainly used as power sources for these devices.

  At present, energetic efforts are being made to increase the energy density of these secondary batteries. However, breakthrough is necessary to dramatically improve the energy density of the power supplies for these devices. Recently, as a breakthrough, it is expected to apply a fuel cell device to a power source. In addition to high energy conversion efficiency of fuel, the fuel cell device can generate electric power as long as fuel supply is continued, so that the device is suitable for a power source of portable electronic devices.

  The fuel cell device includes at least a fuel cell main body and a container for storing fuel. Fuel storage containers are roughly divided into those that store hydrogen and those that store compounds containing hydrogen. Examples of containers that store hydrogen include high-pressure containers, liquefied hydrogen containers, and hydrogen storage alloy containers. Patent Document 1 discloses a technique for supplying hydrogen directly from a hydrogen cylinder to a polymer electrolyte fuel cell. Patent Document 2 discloses a hydrogen filling apparatus in which a hydrogen tank equipped with a hydrogen storage alloy is filled with hydrogen. A polymer electrolyte fuel cell using the above is disclosed.

  An organic compound such as hydrocarbons, alcohols or ethers is stored in a container that stores a compound containing hydrogen. Patent Document 3 discloses a fuel cell device that converts generated hydrogen into electric energy by a fuel cell by reforming a power generation fuel such as an organic compound.

  In the fuel cell device as described above, after the hydrogen rich gas is generated from the organic compound by the reformer, the gas is supplied to the fuel cell. For example, as shown in the equation (3), hydrogen and carbon dioxide are generated from hydrocarbon and water by the reformer. Furthermore, there is a fuel cell device that directly supplies alcohol, ether, and the like to the fuel cell. For example, in a direct methanol fuel cell (DMFC) that supplies methanol to the anode, protons are generated by electrochemically oxidizing methanol at the anode. The reaction at the anode is shown in equation (4). In the cathode, the electrochemical reaction shown in the formula (2) occurs.

C _n H _{2n + 2} + 2nH ₂ O → nCO ₂ + (3n + 1) H ₂ (3)
CH ₃ OH + 2nH ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (4)
Further, a fuel cell device has been developed in which a gas containing hydrogen is generated by decomposing hydrocarbons into carbon and hydrogen using a catalyst, and then this gas is supplied to the fuel cell to obtain electric power. This fuel cell device includes a storage container for storing hydrocarbons, a cracking reactor including a catalyst that decomposes the hydrocarbons into hydrogen and carbon, and an oxidation catalyst that is active in a reaction that oxidizes hydrocarbons or hydrogen. A reactor and a fuel cell are provided. In this fuel cell device, since heat can be supplied from the oxidation reactor to the decomposition reactor, the fuel cell device is small and has high energy density.

JP-A-11-191421 JP 2003-130291 A JP 2002-237321 A

  The energy density of the power source is a value obtained by dividing the integral value of the output and time by the volume or mass of the power source. It is necessary that the fuel cell device and the fuel storage container are light and small in size. In particular, since the amount of fuel loaded is proportional to the time for supplying power, it is desirable that the container for storing the fuel be light and small.

  However, the container for storing hydrogen as described above is not suitable for increasing the energy density of the fuel cell device. For example, a steel high-pressure vessel is used to store hydrogen gas compressed to a high pressure (15 MPa), so that the vessel becomes heavy. Furthermore, when the high-pressure vessel is downsized, the weight of the high-pressure vessel increases with respect to the hydrogen gas, so that the high-pressure vessel is not suitable for downsizing.

  On the other hand, in a container that stores liquefied hydrogen, boil-off in which hydrogen evaporates every few percent is unavoidable, as well as energy loss during the process of liquefying hydrogen and evaporation during the process of filling the liquefied hydrogen. It is not economical because there is a loss due to A container filled with a hydrogen storage alloy has a hydrogen storage amount of several mass%, and therefore, the storage amount per alloy is insufficient to increase the energy density. For this reason, the container filled with the hydrogen storage alloy cannot be sufficiently reduced in size.

  There is a fuel cell device that generates a hydrogen rich gas by reforming an organic compound such as hydrocarbon, alcohol, or ether, and supplies the hydrogen rich gas to a fuel cell. However, the hydrogen rich gas obtained by modifying the organic compound contains carbon monoxide. This carbon monoxide poisons the platinum catalyst, thus significantly reducing the energy conversion efficiency of the fuel cell. There is a method using an apparatus for removing carbon monoxide, but the fuel cell apparatus becomes complicated, so it is not suitable for miniaturization.

  A fuel cell that supplies an organic compound such as alcohol or ether directly to the anode has a lower output density than a fuel cell that supplies hydrogen to the anode because the overvoltage of the electrochemical oxidation reaction of the organic compound is large. That is, since this fuel cell has low energy conversion efficiency, it is not suitable for miniaturization of the fuel cell device.

  A storage container for storing hydrocarbons, a cracking reactor including a catalyst that decomposes the hydrocarbons into hydrogen and carbon, an oxidation reactor including a catalyst that is active in a reaction that oxidizes hydrocarbons or hydrogen, and a fuel cell In the fuel cell device having the above, carbon accumulates in the cracking reactor due to the decomposition of hydrocarbons, and it is necessary to remove this carbon. In order to remove the carbon, an operation of sending air into the decomposition reactor and burning the carbon by heating was performed. However, since the operation is very complicated, the problem is that the convenience of the fuel cell device is poor.

  Therefore, an object of the present invention is to provide a storage container for storing hydrocarbons, a decomposition reactor including a catalyst for decomposing the hydrocarbons into hydrogen and carbon, and a catalyst having activity in a reaction for oxidizing hydrocarbons or hydrogen. By simplifying replenishment and replacement of fuel in a fuel cell device including an oxidation reactor and a fuel cell, the fuel cell device can be operated continuously and the convenience of the fuel cell device is improved. It is in.

  The invention of claim 1 is a storage vessel for storing hydrocarbons, a cracking reactor comprising a catalyst having activity in the hydrocarbon decomposition reaction, an oxidation reactor comprising a catalyst having activity in the hydrocarbon or hydrogen oxidation reaction, and A fuel cell device including a fuel cell is characterized in that at least one of the storage container and the decomposition reactor can be reversibly separated or combined from the fuel cell device.

  In the fuel cell device of the present invention, when the hydrogen generation reaction is completed, by replacing only the storage container, only the decomposition reactor, or both the storage container and the decomposition reactor from the fuel cell device and then replacing them. Since the fuel cell device can be continuously operated, electric power can be continuously supplied to the electronic device. That is, when there is no hydrocarbon stored in the storage container, the fuel cell device can be continuously operated by replacing the empty storage container with a storage container filled with hydrocarbon. Also, by replacing the cracking reactor in which the carbon produced by hydrocarbon decomposition has been replaced with an unused cracking reactor, the complicated operations such as washing and burning to remove the carbon accumulated in the cracking reactor The need for is gone. Further, the fuel cell device can be operated again by exchanging both the storage container and the decomposition reactor. Since the replacement operation is very simple, a highly convenient fuel cell device can be provided. Note that the storage container and the decomposition reactor may be integrated or different from each other.

  The fuel cell device of the present invention comprises a storage container for storing hydrocarbons, a cracking reactor comprising a catalyst having activity in the hydrocarbon decomposition reaction, and an oxidation reactor comprising a catalyst having activity in the hydrocarbon or hydrogen oxidation reaction. And a fuel cell device comprising the fuel cell, wherein at least one of the storage container and the decomposition reactor can be reversibly separated or combined from the fuel cell device.

  In the fuel cell device of the present invention, the hydrocarbon as a raw material of hydrogen is stored in the storage container, the hydrocarbon is supplied from the storage container to the cracking reactor, and the hydrocarbon is converted into carbon by the catalyst in the cracking reactor. Electric power is obtained by decomposing into hydrogen and supplying the generated hydrogen-containing gas to the fuel cell. In the fuel cell device of the present invention, heat is obtained by catalytic combustion of hydrocarbons or hydrogen in the oxidation reactor. By supplying this heat to the cracking reactor, a reaction for decomposing hydrocarbons into carbon and hydrogen proceeds in the cracking reactor. The reaction for decomposing hydrocarbons into hydrogen and carbon is shown in equation (5).

C _n H _{2n + 2} → nC + (n + 1) H ₂ (5)
When the cracking reactor does not contain oxygen, carbon monoxide and carbon dioxide are not generated in the reaction in which the hydrocarbon is decomposed into hydrogen and carbon. That is, the hydrogen-rich gas obtained in this cracking reactor does not contain a component that causes a decrease in the output characteristics of the fuel cell, such as carbon monoxide.

  Decomposition of hydrocarbons in the cracking reactor is an endothermic reaction, but since heat is transferred from the oxidation reactor to the cracking reactor, a hydrogen production reaction by cracking of the hydrocarbon proceeds. The generated hydrogen is used for power generation in the fuel cell. That is, by using the fuel cell device of the present invention including a storage container, a decomposition reactor, an oxidation reactor, and a fuel cell, electric power can be obtained using hydrocarbon as fuel.

  Taking methane as an example of hydrocarbon, methane decomposes to produce hydrogen and carbon. The temperature at which methane decomposes is about 1000 ° C., but the decomposition temperature can be lowered by using a catalyst. The cracking reactor of the fuel cell device of the present invention includes a catalyst that is active in a reaction that decomposes hydrocarbons into carbon and hydrogen.

  Since the hydrocarbon supplied to the cracking reactor is decomposed into carbon and hydrogen by the catalyst, it is possible to generate hydrogen. In the fuel cell device of the present invention, as hydrocarbons, saturated hydrocarbons having 5 or less carbon atoms such as methane, ethane, propane, butane or pentane, alkanes such as ethylene, propylene, butylene or pentene, or ethyne, propyne, Unsaturated hydrocarbons having 5 or less carbon atoms such as alkynes such as butyne and pentyne can be used. Decomposition reactions of alkanes and alkynes are shown in formulas (6) and (7), respectively. However, since saturated hydrocarbons have a higher ratio of hydrogen to carbon than unsaturated hydrocarbons, saturated hydrocarbons are preferably used to supply hydrogen.

C _n H _2n → nC + nH ₂ (6)
_{C n H 2n-2 → nC} + (n-1) H 2 (7)
In order to improve the energy density of the fuel cell device, it is preferable to store the hydrocarbon as a liquid. However, saturated hydrocarbons having up to 4 carbon atoms are gases at room temperature (25 ° C.) and normal pressure (0.1 MPa). These hydrocarbons are liquefied by lowering the temperature or applying pressure. Since the boiling points of methane, ethane, propane, butane and pentane at normal pressure are -169 ° C, -89 ° C, -42.1 ° C, -0.5 ° C and 36.1 ° C, respectively, hydrocarbons are liquefied. It can be seen that the temperature to be reduced decreases as the carbon number decreases. Therefore, much energy is required to liquefy a hydrocarbon having 3 or less carbon atoms, and in addition, the liquefied hydrocarbon must be stored in an insulated container. On the other hand, butane is easily liquefied by applying a pressure of about 0.2 MPa even at room temperature (25 ° C.). Therefore, since butane can maintain a liquid state at a relatively low pressure, it can be stored in a simple sealed container such as a resin sealed container.

  It is preferable to supply gaseous hydrocarbons to the cracking reactor of the fuel cell device of the present invention. The reason is that hydrocarbons that are gaseous rather than liquid are easy to supply uniformly to the catalyst of the cracking reactor. Since the liquefied hydrocarbon having 4 or less carbon atoms is easily vaporized by being discharged from the sealed container, it can be used in this fuel cell device. The boiling point of pentane is vaporized at a relatively low temperature of 36.1 ° C. Since the vaporization heat can be supplied by exhaust heat of the fuel cell, pentane can be used as the fuel of the fuel cell device of the present invention.

  Liquefied butane is preferred for the hydrocarbons used in the fuel cell device of the present invention. The reason for this is that butane can be easily liquefied and vaporized by a pressure of about 0.2 MPa, so that it is excellent in storage and transportation.

  In the fuel cell device of the present invention, a mixture of hydrocarbons having 5 or less carbon atoms can be used. This mixture preferably has butane as the main component. The main component is the one that is contained most in the molar ratio in the mixture. When the butane contained in the mixture is 50 mol% or more, the mixture easily liquefies even at room temperature (25 ° C.) by applying a pressure of about 0.2 MPa. It can be stored in a simple sealed container such as a sealed container. In addition, it can be easily vaporized by supplying the mixture from the sealed container to the fuel cell device.

  For example, a mixture of 90% by mole of butane and 10% by mole of propane is liquefied under the conditions of room temperature (25 ° C.) and 0.2 MPa. By supplying this mixture to the fuel cell device, it is vaporized immediately at room temperature. Therefore, a hydrocarbon mixture composed of a compound of carbon and hydrogen having 5 or less carbon atoms and containing butane as a main component can be easily vaporized in addition to being excellent in storage and transportation. Are suitable.

  The mixture of hydrocarbons can include the aforementioned saturated hydrocarbons and unsaturated hydrocarbons. Furthermore, the mixture of hydrocarbons can contain a saturated hydrocarbon and an unsaturated hydrocarbon in an arbitrary ratio, but preferably contains 50 mol% or more of butane as a main component. Further, in order to facilitate liquefaction and vaporization of the hydrocarbon mixture, it is preferable that 80 mol% or more of butane is contained.

The decomposition reaction formula when butane is used as the hydrocarbon is shown in equation (8). The standard enthalpy change in equation (8) is 125.6 kJmol ⁻¹ . Since this reaction is an endothermic reaction, this hydrogen supply device needs to supply heat to the decomposition reactor, and heat is supplied from the oxidation reactor to the decomposition reactor. That is, in the oxidation reactor, heat is obtained by oxidizing hydrocarbons or hydrogen, and this heat is transferred to the cracking reactor via the heat conducting medium.

C ₄ H ₁₀ → 4C + 5H ₂ (8)
Nickel, a nickel compound, or the like can be used as a catalyst catalyst that is provided in the cracking reactor of the present invention and has an activity in the reaction of cracking hydrocarbons into hydrogen and carbon. For example, as the catalyst, nickel metal (Ni), nickel oxide (NiO), or a mixture of nickel metal (Ni) and nickel oxide (NiO) can be used. Further, after aluminum (Al) is included in Ni or NiO, a part of the Al is removed to increase the surface area of Ni or NiO, or Ni or NiO is Al or nickel sulfide (NiS). A catalyst containing the above can be used as a catalyst. Furthermore, Ni (Ni), tin (Sn), lead (Pb), manganese (Mn), molybdenum (Mo), silver (Ag), chromium (Cr), iron (Fe), cobalt (Co) or copper (Cu) Those containing an element such as can be used as a catalyst.

  By supplying moderate heat to the cracking reactor equipped with the catalyst and introducing hydrocarbons, the hydrocarbon cracking reaction occurs even at 1000 ° C. or lower. The temperature of this decomposition reaction depends on the type and surface area of the catalyst. The surface area of the catalyst is increased by supporting particles such as nickel or a nickel compound on a carrier such as silicon carbide, silicon oxide or alumina. A catalyst having a large surface area is preferable for the catalyst of the cracking reactor of the present invention because of its high activity for the cracking reaction.

  The oxidation reactor includes, for example, a metal container equipped with a catalyst, and the catalyst causes catalytic combustion of hydrocarbons or hydrogen. As the catalyst, nickel, chromium, platinum group metals or compounds thereof can be used, and two or more selected from these substances can be used in combination.

  By supporting fine particles of the catalyst of the oxidation reactor on a ceramic carrier such as alumina, the utilization factor of the catalyst can be improved. Furthermore, the utilization factor of the catalyst can be improved by increasing the surface area of the support. For example, a ceramic made porous by sintering the particle body or a ceramic having a honeycomb structure can be used.

  Hydrogen can be generated by supplying an organic compound containing oxygen in the molecule such as alcohol or ether to the decomposition reactor of the fuel cell device of the present invention. However, in the process of decomposing these organic compounds with a catalyst, oxygen in the molecule may combine with carbon to produce carbon monoxide. Therefore, it is desirable that the organic compound supplied to the decomposition reactor does not contain oxygen atoms in the molecule.

  When oxygen is present in the decomposition reactor, carbon monoxide may be generated during the decomposition reaction. Therefore, the organic compound supplied to the decomposition reactor is preferably in a deoxygenated state. Furthermore, when the organic compound contains water, a steam reforming reaction occurs and carbon monoxide may be generated, which is not preferable.

  As the electrolyte of the unit cell of the fuel cell used in the fuel cell device of the present invention, a polymer film, a matrix impregnated with alkali or acid, molten carbonate, solid oxide, or the like can be used. Since the polymer electrolyte membrane functions as an electrolyte at a temperature of 100 ° C. or lower, it is suitable for operating the fuel cell device at a relatively low temperature. For example, a membrane made of perfluorosulfone resin can be used as the polymer electrolyte membrane. This membrane exhibits high proton conductivity at room temperature. A fuel cell using this membrane as an electrolyte is called a polymer electrolyte fuel cell.

  Since the fuel cell device of the present invention has a high energy density, the device is preferable as a power source for electronic equipment. Since the energy density of this fuel cell device is determined according to the amount of hydrocarbons, the amount of hydrocarbons loaded can be selected according to the electronic equipment. By changing the amount of hydrocarbon loaded according to the power consumption and operating time of the electronic device, it is possible to make the electronic device small and lightweight. For example, when using as a power source for a relatively small charger such as a mobile phone or a shaver, the amount of hydrocarbons is reduced, while when using as a power source for a relatively large charger such as a power tool, The load can be increased. Furthermore, when an electronic device with relatively large power consumption such as a mobile computer is continuously used, the electronic device can be operated for a long time by replenishing the fuel cell device with hydrocarbons.

  The fuel cell device of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a fuel cell device according to the present invention. In FIG. 1, 1 is a storage container, 2 is a decomposition reactor, 3 is a thermal insulation for the decomposition reactor, 4 is a fuel pipe, 5 Is a fuel valve, 6 is an integrated body of a storage container and a decomposition reactor, 7 is an oxidation reactor, 8 is an insulation material for the oxidation reactor, 9 is a fuel cell, 10 is a heat exchanger, 11 is a hydrogen supply pipe, 12 Is a discharge hydrogen introduction pipe, 13 is an air introduction pipe, and 14 is a discharge pipe.

  The main components of the fuel cell device of the present invention are a storage container 1, a decomposition reactor 2, an oxidation reactor 7 and a fuel cell 9. The storage container 1 and the decomposition reactor 2 are connected by a fuel pipe 4. Through this connection pipe 4, hydrocarbons are supplied from the storage container 1 to the cracking reactor 2. The fuel pipe 4 is provided with a fuel valve 5. The fuel supply amount can be controlled by the fuel valve 5.

  Heat is supplied to the decomposition reactor 2 from the oxidation reactor 7 via the heat exchanger 10. The cracking reactor 2 and the oxidation reactor 7 are respectively provided with a thermal insulation 3 for the decomposition reactor and a thermal insulation 8 for the oxidation reactor to prevent heat from being lost outside the fuel cell device. .

  The hydrocarbons supplied to the cracking reactor 2 are decomposed into carbon and hydrogen by the catalyst. Since carbon is produced on the catalyst and accumulated in the cracking reactor 2, hydrogen is supplied to the fuel cell 9 through the hydrogen supply pipe 11 and then is electrochemically oxidized in the fuel cell 9. . The fuel cell 9 can generate electric power by this electrochemical reaction. A part of the hydrogen supplied to the fuel cell 9 is not oxidized electrochemically. The hydrogen that has not been oxidized is introduced from the fuel cell 9 to the oxidation reactor 7 through the exhaust hydrogen introduction pipe 12, and then oxidized by catalytic combustion in the oxidation reactor 7. For this oxidation reaction, air introduced into the oxidation reactor 7 from the air introduction tube 13 is used. Heat is generated by catalytic combustion of hydrogen in the oxidation reactor 7. The heat is supplied to the cracking reactor 2 through the heat exchanger 10 as described above.

  The fuel cell device of the present invention generates electricity by supplying hydrocarbons as fuel. The power supply by the fuel cell device is terminated when the hydrocarbons in the storage container 1 are consumed, but the power supply is started again by replenishing the storage container 1 with hydrocarbons. On the other hand, carbon produced by cracking hydrocarbons accumulates in the cracking reactor 2. This accumulation of carbon lowers the action of a catalyst that is active in the reaction of decomposing hydrocarbons into hydrogen and carbon, thereby preventing the progress of the hydrocarbon decomposition reaction. Therefore, in order to obtain electric power continuously by the fuel cell device, the carbon accumulated in the decomposition reactor 2 must be removed.

  As a method of removing carbon from the cracking reactor 2, there is a method of oxidizing carbon to carbon dioxide by supplying air (oxygen) to the cracking reactor and heating it. This method is not suitable for continuously obtaining electric power from the fuel cell device in addition to the complicated operation.

  On the other hand, in the fuel cell device of the present invention, electric power can be continuously supplied by exchanging the integrated body of the storage container and the decomposition reactor. The separation or connection of the storage vessel and the decomposition reactor can be performed in a single operation. For example, it is possible to combine the storage container and the decomposition reactor by inserting them into the fuel cell device, and conversely, by separating the storage container and the decomposition reactor from the fuel cell device. . Since the coupling and separation operations are very simple, it is possible to exchange the integrated body of the storage container and the decomposition reactor in a short time.

  The structure of the integrated body of the storage container and the decomposition reactor will be specifically described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing a state in which the integrated body of the storage container and the decomposition reactor is separated from the fuel cell device of the present invention. The main components of the integrated body 6 of the storage container and the decomposition reactor are a storage container 1 and a decomposition reactor 2, and the decomposition reactor 2 is covered with a heat insulating material 2. Since the heat insulating material 2 is disposed between the storage container 1 and the decomposition reactor 2, the heat of the decomposition reactor 2 is not excessively transferred to the storage container 1.

  Further, in the integrated body of the storage container and the decomposition reactor, the value obtained by dividing the volume of the decomposition reactor 2 by the volume of the storage container 1 is preferably between 0.30 and 0.67. If the value is less than 0.30, the packing density of the produced carbon in the cracking reactor 2 becomes excessively high, so that a smooth cracking reaction of hydrocarbons is hindered. On the other hand, when the value is 0.67 or more, the volume of the integrated body of the storage container and the decomposition reactor becomes excessively large, so that the energy density of the fuel cell device is lowered. In the fuel electric device of the present invention, electric power can be continuously obtained by exchanging the integrated body of the storage container and the decomposition reactor.

  In the fuel cell device of the present invention, the storage container and the cracking reactor can be replaced not only with each other but also with either the storage container or the cracking reactor. In this case, the storage container and the decomposition reactor may be connected to the fuel cell device in an independent state without being integrated.

  The fuel cell 9 shown in FIGS. 1 and 2 is composed of one or a plurality of single cells. A schematic diagram of a cross section of a unit cell of the fuel cell 9 is shown in FIG. In FIG. 3, 21 is a cell, 22 is an electrolyte, 23 is an anode, 24 is a cathode, 25 is an anode current collector, 26 is a cathode current collector, and 27 is an external load.

  The unit cell 21 includes an anode 23 on one surface of the electrolyte 22 and a cathode 24 on the other surface. The anode 23 includes an anode current collector 25, and the cathode 24 includes a cathode current collector 26. The anode current collector 25 and the cathode current collector 26 are electrically connected via an external load 27.

  At the anode 23, hydrogen is electrochemically oxidized as shown in the equation (1). Electrons generated by this reaction are guided to the cathode 24 via the anode current collector 25, the external load 27 and the cathode current collector 26. At the cathode 24, oxygen is electrochemically reduced as shown in equation (2). That is, the single cell 21 is an electrochemical device that causes hydrogen and oxygen to react electrochemically.

  When the fuel cell 9 is composed of a plurality of single cells 21, the single cells 21 are electrically connected in parallel, in series, or in parallel and in series according to the power consumption or operating voltage of the electronic device to be used. Can be connected. By connecting the unit cells 21 in parallel, a fuel cell device suitable for extracting a large current can be obtained. Moreover, the fuel cell apparatus suitable for taking out a high voltage is obtained by connecting the unit cells 21 in series.

  According to the fuel cell device of the present invention, electric power can be obtained using hydrocarbon as fuel. The fuel cell 9 is supplied with hydrogen generated from hydrocarbons. Since this hydrogen does not contain carbon monoxide that poisons the electrode catalyst of the fuel cell, the operating voltage of the fuel cell is improved. Since the hydrogen discharged from the fuel cell is used in the reaction for generating hydrogen from the hydrocarbon, the thermal efficiency of the entire fuel cell device can be increased. Therefore, it is possible to provide a fuel cell device that is small and has high energy density.

  The features of the fuel cell device of the present invention are as follows.

  1. Oxidation reaction comprising a storage vessel for storing hydrocarbons, a cracking reactor comprising a catalyst active in the reaction of cracking hydrocarbons into hydrogen and carbon, and a catalyst active in the reaction of oxidizing hydrocarbons or hydrogen And a fuel cell device, wherein at least one of the storage container and the decomposition reactor can be reversibly separated or combined. That is, in a fuel cell device that reversibly separates or combines the storage container or the decomposition reactor from the fuel cell device, or reversibly separates or combines the storage vessel and the decomposition reactor from the fuel cell device. is there.

  2. Use butane as the hydrocarbon. The hydrocarbon is a mixture of hydrocarbons having 5 or less carbon atoms, and the main component of the mixture is butane.

  3. The value obtained by dividing the volume of the cracking reactor by the volume of the storage container is between 0.30 and 0.67.

  4). The catalyst provided in the cracking reactor is nickel or a nickel compound.

  5). The catalyst provided in the oxidation reactor is at least one selected from the group consisting of nickel, chromium, platinum group metals or compounds thereof.

  6). The fuel cell is a polymer electrolyte fuel cell.

  7). The fuel cell has at least two or more unit cells, and these unit cells are electrically connected in parallel or in series.

  The present invention will be described below with reference to preferred embodiments.

[Example 1]
A specific example of the fuel cell device of the present invention will now be described. After impregnating the silicon carbide particles with an aqueous solution of Ni (NO ₃ ) ₂ , drying, firing, and hydrogen reduction were performed to support the nickel fine particles on the silicon carbide. The amount of nickel supported was about 5 mass%. About 15 g of silicon carbide carrying nickel was filled in a stainless steel container. The internal volume of the container was about 200 cm ³ . This vessel was used as a cracking reactor for hydrocarbon cracking. The storage container was filled with 180 g of liquefied butane. The internal volume of this storage container was about 300 cm ³ . And the integral thing of the storage container and the decomposition reactor was comprised.

After impregnating the aluminum oxide particles with an aqueous solution of Pt (NH ₃ ) ₄ (OH) ₂ , drying, firing, and hydrogen reduction were performed, thereby supporting platinum fine particles on the aluminum oxide. The amount of platinum supported was about 3 mass%. About 50 g of aluminum oxide carrying platinum was filled in a stainless steel container having an internal volume of about 40 cm ³ . This vessel was used as an oxidation reactor equipped with a catalyst having activity in the reaction of oxidizing hydrocarbons or hydrogen.

  After the oxidation reactor and the 20 W class fuel cell were installed in the fuel cell device frame, the integrated unit of the storage container and the decomposition reactor was combined to constitute the fuel cell device. The fuel cell device was then operated according to the procedure.

First, supply of butane and air to the oxidation reactor was started. The supply amount of butane was set to 10 ml min ⁻¹ and the mixture was allowed to stand for about 10 minutes, and then the supply of butane from the storage container to the oxidation reactor was stopped. At this time, since heat is conducted from the oxidation reactor to the decomposition reactor, the temperature of the decomposition reactor reaches a temperature at which butane decomposes into hydrogen and carbon.

Next, the fuel valve provided in the fuel pipe was opened, and the supply of butane from the storage container to the decomposition reactor was started. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. At this time, by adjusting the fuel valve, about 50 ml min ⁻¹ of butane was supplied to the cracking reactor. Under this condition, this fuel cell device could be stably operated at 20 W output for 21 hours. After that, the output of the fuel cell became unstable, so the load on the fuel cell was cut off and power generation was stopped.

  According to Example 1, it was confirmed that the fuel cell device of the present invention using an integrated body of a storage container storing butane and a cracking reactor filled with nickel carbide loaded with nickel can be used as a small power source. It was.

[Example 2]
From the fuel cell device whose operation was stopped in Example 1, the integrated body of the storage container and the decomposition reactor was separated. Then, the same unit of the new storage container and the decomposition reactor similar to that used in Example 1 was re-coupled to the fuel cell device. Subsequently, about 50 mlmin ⁻¹ butane was supplied by opening the fuel valve. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. Under this condition, this fuel cell device could be stably operated at 20 W output for 21.7 hours. After that, the output of the fuel cell became unstable, so the load on the fuel cell was cut off and power generation was stopped.

  In the fuel cell device of the present invention using an integral body of a storage container and a cracking reactor filled with butane according to Example 2, it is repeatedly used by exchanging the integral body of the storage container and the cracking reactor. It was confirmed that it could be done.

[Example 3]
As in Example 1, a storage vessel comprising 90 g of liquefied butane, a decomposition reactor made of stainless steel containing about 15 g of silicon carbide carrying nickel, an oxidation reactor comprising a catalyst active in an oxidation reaction, and a fuel comprising a fuel cell A battery device was constructed. The reservoir, the internal volume of the decomposition reactor and the oxidation reactor is respectively 150 cm ^3, it was about 200 cm ³ and about 40 cm ^3.

This fuel cell device was operated in the same procedure as in Example 1. First, supply of butane and air to the oxidation reactor was started. The supply amount of butane was set at 10 mlmin ⁻¹ and the mixture was left for about 10 minutes, and then the supply of butane from the storage container to the oxidation reactor was stopped. At this time, since heat is conducted from the oxidation reactor to the decomposition reactor, the temperature of the oxidation reactor reaches a temperature at which butane decomposes into hydrogen and carbon. Next, the fuel valve provided in the fuel pipe was opened, and the supply of butane from the storage container to the decomposition reactor was started. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. At this time, by adjusting the fuel valve, about 50 ml min ⁻¹ of butane was supplied to the cracking reactor. Under this condition, this fuel cell device could be stably operated at 20 W output for 10 hours.

Subsequently, after the storage container was separated from the fuel cell device, another storage container equipped with 90 g of liquefied butane was connected to the device again. After that, by opening the fuel valve, about 50 ml min ⁻¹ butane was supplied. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. Under this condition, this fuel cell device could be stably operated at 20 W output for 10.8 hours. After that, the output of the fuel cell became unstable, so the load on the fuel cell was cut off and power generation was stopped.

  The experiment shown in Example 3 confirmed that this fuel cell device can be used repeatedly by exchanging it with a storage container storing butane.

[Example 4]
Similarly to Example 1, a storage container provided with 180 g of liquefied butane, a decomposition reactor made of about 7.5 g of silicon carbide carrying nickel and made of stainless steel, an oxidation reactor equipped with a catalyst having activity in an oxidation reaction, and a fuel cell A fuel cell device provided was configured. The reservoir, the internal volume of the decomposition reactor and the oxidation reactor is respectively 300 cm ^3, it was about 100 cm ³ and about 40 cm ^3.

This fuel cell device was operated in the same procedure as in Example 1. First, supply of butane and air to the oxidation reactor was started. The supply amount of butane was set at 10 mlmin ⁻¹ and the mixture was left for about 10 minutes, and then the supply of butane from the storage container to the oxidation reactor was stopped. At this time, since heat is conducted from the oxidation reactor to the decomposition reactor, the temperature of the oxidation reactor reaches a temperature at which butane decomposes into hydrogen and carbon. Next, the fuel valve provided in the fuel pipe was opened, and the supply of butane from the storage container to the decomposition reactor was started. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. At this time, by adjusting the fuel valve, about 50 ml min ⁻¹ of butane was supplied to the cracking reactor. Under this condition, the fuel cell device was stably operated at 20 W output for 10 hours and then stopped.

Subsequently, after separating the cracking reactor from the fuel cell device, another cracking reactor comprising about 7.5 g of silicon carbide carrying nickel was re-coupled to the device. After that, by opening the fuel valve, about 50 ml min ⁻¹ butane was supplied. Thirty seconds later, a 20 W output was generated by connecting a load to the fuel cell. Under this condition, this fuel cell device could be stably operated at 20 W output for 11 hours. After that, the output of the fuel cell became unstable, so the load on the fuel cell was cut off and power generation was stopped.

  The experiment shown in Example 4 confirmed that this fuel cell device can be used repeatedly by replacing it with another cracking reactor comprising silicon carbide carrying nickel.

[Comparative Example 1]
As Comparative Example 1, a fuel cell device having the same specifications as in Example 1 was produced and then operated for 21 hours under the same conditions as in Example 1. Next, the storage container of the apparatus was filled with 180 g of liquefied butane. Further, oxygen was circulated for 30 minutes while the decomposition reaction of the apparatus was heated to 700 ° C. After this filling and distribution operation, the apparatus was again operated under the same conditions as in Example 1. Its operating time was 19.2 hours. In the apparatus of Comparative Example 1, it was found that the output density was lowered in addition to the very complicated operation. From this result, it became clear that the fuel cell device of the present invention is excellent in convenience and performance.

The schematic diagram of the cross section of the fuel cell apparatus of this invention. The schematic diagram of the cross section of the fuel cell apparatus of this invention in the state from which the integrated object of the storage container and the decomposition reactor was isolate | separated. The schematic diagram of the cross section of the single cell which comprises a fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage container 2 Decomposition reactor 6 Integration thing of a storage container and a decomposition reactor 7 Oxidation reactor 9 Fuel cell 21 Single cell

Claims (1)

Storage vessel for storing hydrocarbon, cracking reactor equipped with catalyst having activity in cracking reaction of hydrocarbon, oxidation reactor comprising catalyst having activity in hydrocarbon or hydrogen oxidation reaction, and fuel cell equipped with fuel cell In the apparatus, at least one of the storage container and the decomposition reactor can be reversibly separated or coupled from the fuel cell apparatus.

Images