JP2012014872A - Dmfc type fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DMFC type fuel battery that can use biomethanol containing impurities.SOLUTION: The DMFC type fuel battery uses biomethanol as fuel, and has a negative electrode, a positive electrode, and an electrolyte layer arranged between both electrodes. The fuel is supplied from a biomethanol source to the negative electrode through a flow passage connected to the biomethanol source and negative electrode, and an activated carbon layer including activated carbon is provided to at least a part of the flow passage.

Description

  The present invention relates to a fuel cell, and more particularly to a DMFC type fuel cell using methanol as a fuel.

  Fuel cells are expected to be applied to various fields as clean energy sources that convert chemical energy into electrical energy. In particular, a DMFC type fuel cell (Direct Methanol Fuel Cell) is suitable for a power source of a portable electronic device or the like because of its low operating temperature and relatively easy miniaturization (for example, Patent Document 1).

In the DMFC type fuel cell, methanol (CH ₃ OH) is used as a fuel. Usually, this methanol is industrially produced by an organic chemical synthesis method using a fossil fuel such as natural gas as a raw material. In this production method, high-purity methanol with extremely few impurities such as sulfur compounds is produced.

  However, a method for producing methanol using fossil fuel as a raw material is not preferable from the viewpoint of the future depletion of fossil fuel, protection of the global environment, and the like.

  Therefore, instead of producing methanol from fossil fuels, a technique for producing methanol from renewable raw materials such as plants has been studied. Such methanol is also particularly referred to as “biomethanol”.

"Bio-methanol", for example, or fermented grains and timber resources (non-food resources), by these high-temperature decomposed, CO, syngas (CO, such as H ₂ is the active ingredient) including such as H ₂ And is further produced by reacting this synthesis gas in the presence of a catalyst.

  In such a method, since biomethanol is obtained using plant resources grown by photosynthesis of solar energy, it is possible to produce this biomethanol semipermanently. That is, in this method, biomethanol can be used as a renewable energy source.

JP 2005-235552 A

  However, since biomethanol is produced from plant resources in which various chemical substances are mixed, the obtained biomethanol contains a large amount of impurities (for example, sulfur components such as sulfur compounds). In addition, even if treatment for increasing methanol purity is performed in the biomethanol production process, it is difficult to completely remove impurities such as sulfur components.

  In addition, when a sulfur component is present in biomethanol, the activity of a catalyst such as platinum (Pt) used in the DMFC type fuel cell is reduced (poisoned), and the power generation efficiency of the fuel cell is reduced. For this reason, at present, biomethanol is mainly used as a fuel for an internal combustion engine such as an engine in a purified state.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a DMFC-type fuel cell capable of using a biomethanol fuel containing impurities such as a sulfur component.

In the present invention,
A DMFC type fuel cell having a negative electrode, a positive electrode, and an electrolyte layer disposed between the two electrodes,
The DMFC type fuel cell uses biomethanol as fuel,
The fuel is supplied from a biomethanol source to the negative electrode through a flow passage connected to the biomethanol source and the negative electrode,
A DMFC type fuel cell is provided in which an activated carbon layer having activated carbon is provided in at least a part of the flow passage.

  Here, in the DMFC type fuel cell according to the present invention, the activated carbon layer may be disposed adjacent to the negative electrode on a side of the negative electrode opposite to the electrolyte layer.

The DMFC fuel cell according to the present invention further includes a fuel tank as the biomethanol source.
A second activated carbon may be installed in the fuel tank.

  In the DMFC fuel cell according to the present invention, a mixture of biomethanol and methanol produced from fossil fuel may be used as fuel.

  The DMFC fuel cell according to the present invention may further include means for cleaning the activated carbon of the activated carbon layer.

  In the DMFC fuel cell according to the present invention, the flow path may include a fluid inlet for cleaning the activated carbon of the activated carbon layer and a fluid outlet.

  In the DMFC fuel cell according to the present invention, the fluid for cleaning the activated carbon of the activated carbon layer may be hot water and / or hot air.

  In the present invention, it is possible to provide a DMFC type fuel cell that can use a biomethanol fuel containing impurities such as a sulfur component.

It is the figure which showed schematically the structure of the conventional DMFC type fuel cell. It is the figure which showed roughly the example of 1 structure of the DMFC type fuel cell by this invention. It is the figure which showed the mode of reaction in the negative electrode vicinity. It is the figure which showed the mode of reaction in a positive electrode. It is data explaining the effect of the DMFC type fuel cell shown in FIG. It is the figure which showed schematically another structural example of the DMFC type fuel cell by this invention. It is the figure which showed schematically another example of 1 structure of the DMFC type fuel cell by this invention. FIG. 8 is a diagram showing an example of a change over time in power generation performance in the DMFC type fuel cell 300 shown in FIG. 7. It is the figure which showed an example of the cleaning method of the activated carbon layer used for a DMFC type fuel cell. It is a figure which shows the effect of the cleaning method of the activated carbon layer shown in FIG. It is the figure which showed an example of another cleaning method of the activated carbon layer used for a DMFC type fuel cell. It is a figure which shows the effect of the cleaning method of the activated carbon layer shown in FIG.

  The configuration of the present invention will be described below with reference to the drawings.

  First, in order to better understand the features of the present invention, the operation of a conventional DMFC type fuel cell will be briefly described with reference to FIG.

  As shown in FIG. 1, a conventional DMFC type fuel cell 10 includes a fuel tank 11 and a fuel cell main body 30. The fuel tank 11 is filled with methanol. The fuel cell main body 30 includes a negative electrode (fuel electrode) 60 having a negative electrode catalyst layer 60A, a positive electrode (air electrode) 80 having a positive electrode catalyst layer 80A, an electrolyte membrane 70 disposed between both electrodes 60, 80, Have Further, the methanol layer 40 is provided on the side of the negative electrode 60 opposite to the electrolyte membrane 70. An air layer 90 is provided on the side of the positive electrode 80 opposite to the electrolyte membrane 70.

  The methanol layer 40 has a role of distributing methanol, which is fuel, to the negative electrode 60 from the fuel tank 11 provided outside the fuel cell main body 30 through the fuel intake port 20a. On the other hand, the air layer 90 has a role of distributing air to the positive electrode 80 from an air (oxygen) source (not shown) provided outside the fuel cell main body 30 through the air intake port 20b.

In such a configuration of the DMFC type fuel cell 10, first, methanol is supplied from the fuel tank 11 to the fuel cell main body 30 through the fuel intake port 20 a. Methanol supplied to the fuel cell main body 30 is introduced into the negative electrode 60 through the methanol layer 40. Methanol is oxidized in the negative electrode 60 by the action of the catalyst particles in the negative electrode catalyst layer 60A, and is decomposed into hydrogen ions (H ⁺ ), carbon dioxide (CO ₂ ), and electrons (e ⁻ ).

  Hydrogen ions generated at the negative electrode 60 pass through the electrolyte membrane 70 and move toward the positive electrode 80. The electrons move toward the positive electrode 80 via the external load 25 connected to the negative electrode 60.

  On the other hand, oxygen is supplied from the external air source to the fuel cell main body 30 through the air intake port 20b. Oxygen supplied to the fuel cell main body 30 is introduced into the positive electrode 80 through the air layer 90. When oxygen comes into contact with the positive electrode catalyst layer 80A of the positive electrode 80, oxygen is reduced by the above-described hydrogen ions and electrons by the action of the catalyst particles in the positive electrode catalyst layer 80A, and water is generated.

  In the above process, when electrons pass through the external load 25, the DMFC type fuel cell 10 can perform work to the outside (electrical energy is released).

  Here, in DMFC-type fuel cells so far, methanol used as fuel has been produced using fossil fuel as a raw material, but from the viewpoint of future fossil fuel depletion and global environmental protection, etc., methanol It is conceivable to use biomethanol.

  However, since biomethanol is produced from plant resources in which various chemical substances are mixed, the obtained biomethanol contains many impurities such as sulfur compounds. Therefore, when such biomethanol with a large amount of impurities is used as fuel for the DMFC type fuel cell, the activity of the catalyst such as platinum (Pt) contained in the catalyst layer is reduced (poisoned), and the power generation efficiency of the fuel cell is reduced. May decrease.

In contrast, in the present invention,
A DMFC type fuel cell having a negative electrode, a positive electrode, and an electrolyte layer disposed between the two electrodes,
The DMFC type fuel cell uses biomethanol as fuel,
The fuel is supplied from a biomethanol source to the negative electrode through a flow passage connected to the biomethanol source and the negative electrode,
A DMFC type fuel cell is provided in which an activated carbon layer having activated carbon is provided in at least a part of the flow passage.

  In such a DMFC type fuel cell, even if impurities such as a sulfur component are contained in biomethanol, such impurities are adsorbed and removed by the activated carbon layer before reaching the negative electrode. For this reason, biomethanol in which the amount of impurities is significantly suppressed can be supplied to the negative electrode.

  Therefore, in the DMFC type fuel cell of the present invention, even when biomethanol containing impurities such as sulfur components is used as a fuel, the catalyst in the negative electrode catalyst layer is poisoned or the performance of the fuel cell is lowered. Is significantly suppressed.

  Here, in the present invention, if necessary, activated carbon may be installed in advance in a biomethanol storage fuel tank. Thus, for example, during the period from when the fuel tank is manufactured at the factory to when the fuel tank is actually used, impurities in the biomethanol filled in the fuel tank are adsorbed to the activated carbon in advance. be able to.

  Furthermore, methanol with less impurities produced from fossil fuel and biomethanol containing impurities may be mixed and supplied to the fuel cell. In this case, the concentration of impurities contained in the methanol supplied to the fuel cell can be relatively lowered.

  Note that when the amount of impurities adsorbed on the activated carbon layer increases, the activated carbon layer may have a reduced ability to remove impurities. Therefore, it is preferable to occasionally perform cleaning of the activated carbon layer in order to recover the impurity removal capability of the activated carbon layer.

  The cleaning method of the activated carbon layer is not limited to this, but for example, a method of supplying warm water or air of 90 ° C. or less to the activated carbon layer to remove the adsorbed sulfur component may be used.

(Configuration of DMFC type fuel cell according to the present invention)
Hereinafter, the DMFC fuel cell according to the present invention will be described in more detail with reference to the drawings.

  FIG. 2 schematically shows an example of a DMFC type fuel cell according to the present invention.

  As shown in FIG. 2, a DMFC type fuel cell 100 according to the present invention has a configuration substantially similar to that of the conventional DMFC type fuel cell 10 shown in FIG.

  That is, the DMFC type fuel cell 100 includes a fuel cell main body 130 and a fuel tank 111 connected to the fuel intake port 120 a of the fuel cell main body 130. The fuel cell main body 130 includes a negative electrode 160 having a negative electrode catalyst layer 160A, a positive electrode 180 having a positive electrode catalyst layer 180A, and an electrolyte membrane 170 disposed between both electrodes.

  The negative electrode catalyst layer 160A is configured by supporting a catalyst such as platinum and / or ruthenium on a negative electrode material such as carbon. The positive electrode catalyst layer 180A is configured by supporting a catalyst such as platinum and / or ruthenium on a positive electrode material such as carbon. The electrolyte membrane 170 may be any membrane as long as it is a hydrogen ion permeable organic membrane.

  The fuel tank 111 is filled with biomethanol purified from plants such as wood chips, for example.

  In the example of FIG. 2, the methanol layer 140 is provided between the activated carbon layer 150 and the fuel intake port 120a, although not necessarily essential in the present invention. The methanol layer 140 functions as a space for temporarily storing the fuel supplied from the fuel tank 111.

  Here, the DMFC type fuel cell 100 is different from the conventional DMFC type fuel cell 10 shown in FIG. 1 in that the anode 160 has an activated carbon layer 150 containing activated carbon on the side opposite to the electrolyte membrane 170. Have.

  In the example of FIG. 2, the activated carbon layer 150 is disposed so as to be adjacent to the negative electrode 160. However, the arrangement position of the activated carbon layer 150 is not limited to this. That is, the activated carbon layer 150 may be provided at any position in the fuel passage between the fuel tank 111 and the negative electrode 160. For example, the activated carbon layer 150 may be provided in the fuel intake port 120a. Further, for example, the activated carbon layer 150 may be disposed in the entire methanol layer 140. Further, for example, the activated carbon layer 150 may be installed in the entire fuel flow path between the fuel tank 111 and the negative electrode 160. However, if the installation area of the activated carbon layer 150 is widened, the fuel pressure loss may increase accordingly. Therefore, in the normal case, the activated carbon layer 150 is preferably installed in a part of the fuel flow path. For example, the activated carbon layer 150 is preferably installed so as to cover the entire surface of the negative electrode 160 in a state where the thickness of the activated carbon layer is reduced within a range where a sufficient adsorption effect can be expected as shown in FIG. .

  In the DMFC type fuel cell 100 having such a characteristic configuration, when operated, biomethanol is supplied from the fuel tank 111 to the fuel cell main body 130 through the fuel intake port 120a. Biomethanol is first supplied to the methanol layer 140.

  Next, biomethanol flows through the activated carbon layer 150. At this time, impurities such as sulfur components contained in the biomethanol are adsorbed on the activated carbon. Therefore, the biomethanol released from the activated carbon layer 150 is in a “clean” state with almost no impurities.

  Thereafter, the biomethanol from which the impurities are removed is circulated in the negative electrode 160. Impurities such as sulfur components contained in biomethanol are extremely small. For this reason, even if biomethanol flows into the negative electrode 160, the risk of poisoning of the catalyst of the negative electrode catalyst layer 160A is significantly suppressed. In the negative electrode catalyst layer 160A, biomethanol is used for the oxidation reaction as described above.

  FIG. 3 shows a schematic diagram when biomethanol containing impurities such as a sulfur component passes through the activated carbon layer 150 and is supplied to the negative electrode 160.

As shown in FIG. 3, when biomethanol containing impurities passes through the activated carbon layer 150, the impurities are adsorbed on the activated carbon 152 of the activated carbon layer 150. Therefore, the biomethanol released from the activated carbon layer 150 is in a “clean” state containing almost no impurities, that is, “high purity” methanol. Therefore, methanol is introduced into the negative electrode 160. This methanol is oxidized on the carbon particles 363 in the negative electrode 160 by the action of catalyst particles (such as platinum and / or ruthenium) 362 in the negative electrode catalyst layer 160A, and hydrogen ions, CO ₂ and electrons are generated.

  On the other hand, air (or oxygen) is introduced into the positive electrode 180 through the air intake 120b of the fuel cell body.

  FIG. 4 is a schematic diagram when oxygen is supplied to the positive electrode 180 through the air layer 190.

  As shown in FIG. 4, oxygen supplied into the fuel cell main body is distributed and introduced to the positive electrode 180 through the air layer 190. In the positive electrode 180, oxygen is reduced on the carbon particles 463 by the action of catalyst particles (such as platinum and / or ruthenium) 462 included in the positive electrode catalyst layer 180 </ b> A. That is, oxygen reacts with hydrogen ions that have diffused from the negative electrode 160 through the electrolyte membrane 170 and electrons that have reached the positive electrode 180 via an external load, thereby generating water.

  As described above, in the fuel cell 100 according to the present invention, it is possible to appropriately generate power by the fuel cell 100 while avoiding the risk of poisoning of the catalyst in the negative electrode catalyst layer 160A included in the negative electrode 160. It becomes.

  FIG. 5 shows data explaining the effect of the DMFC type fuel cell shown in FIG.

  FIG. 5A shows current density (current value per unit area of the electrolyte membrane 170 of the fuel cell 100) and voltage (negative electrode terminal 125A of the external load 125) in the initial power generation of the DMFC type fuel cell shown in FIG. 3 is a graph showing the relationship between the voltage between the positive terminals 125C) and the relationship between the current density and the power density (the amount of power generated per unit area of the electrolyte membrane 170 of the fuel cell 100).

  As a fuel, a biomethanol aqueous solution in which a 100% biomethanol solution was diluted to 60% with pure water was used.

In the example of this data, when the current density is about 200 mA / cm ² , the power generation density becomes maximum, and the maximum power generation density peak (about 28 mW / cm ² ) is obtained.

  FIG. 5B is a graph showing a change with time of the maximum power generation density peak during power generation when the DMFC fuel cell is continuously operated (power generation). In the figure, for comparison, the results in a DMFC type fuel cell not having an activated carbon layer are also shown.

  From this graph, it can be seen that in the DMFC fuel cell according to the present invention having the activated carbon layer, the decrease in the maximum power generation density peak is suppressed as compared with the case without the activated carbon layer.

  Thus, in this invention, even if it is a case where the biomethanol fuel containing an impurity is used as a fuel, the fall of the electric power generation characteristic of a fuel cell can be suppressed significantly.

(Second configuration)
Next, another configuration of the DMFC type fuel cell according to the present invention will be described with reference to FIG.

  FIG. 6 shows another configuration of the DMFC type fuel cell according to the present invention.

  As shown in FIG. 6, this DMFC type fuel cell 200 has basically the same configuration as the DMFC type fuel cell 100 shown in FIG. Therefore, in FIG. 6, the same reference numerals as in FIG. 2 are attached to the same members as those of the DMFC-type fuel cell 100.

  However, the DMFC type fuel cell 200 further has a feature of having activated carbon 212 in the fuel tank 111.

  In this case, the impurities in the biomethanol can be adsorbed on the activated carbon 212 in a state where the fuel tank 111 is filled with the biomethanol at a manufacturing factory or the like, thereby reducing the impurity concentration in the biomethanol.

  In such a DMFC-type fuel cell 200, when supplying biomethanol to the fuel cell main body 130, biomethanol having already reduced the concentration of impurities can be introduced.

(Third configuration)
Next, another configuration of the DMFC type fuel cell according to the present invention will be described with reference to FIG.

  FIG. 7 shows another configuration of the DMFC type fuel cell according to the present invention.

  As shown in FIG. 7, this DMFC type fuel cell 300 has basically the same configuration as the DMFC type fuel cell 200 shown in FIG. Therefore, in FIG. 7, the same reference numerals as in FIG. 6 are attached to the same members as those of the DMFC-type fuel cell 200.

  However, in this DMFC type fuel cell 300, the fuel tank 111 is not filled with biomethanol alone but mixed methanol containing both biomethanol and methanol produced from fossil fuel such as natural gas. Has characteristics.

  In general, methanol produced from fossil fuel (hereinafter simply referred to as “fossil fuel methanol”) has a low content of impurities such as sulfur components. In this case, even if biomethanol produced from plants such as wood chip contains impurities such as a considerable amount of sulfur component, the impurity concentration in the methanol fuel can be relatively lowered. Accordingly, even in the configuration of the DMFC type fuel cell 300, the effects of the present invention as described above can be obtained, that is, the risk of poisoning of the catalyst particles of the negative electrode catalyst layer is reduced, and the characteristics of the fuel cell are deteriorated. Can be suppressed.

  FIG. 8 shows an example of a change with time in power generation performance (maximum power generation density peak) in such a DMFC-type fuel cell 300. As methanol contained in the fuel tank 111, (a) 1% biomethanol + 99% fossil fuel methanol and (b) 50% biomethanol + 50% fossil fuel methanol were used. For comparison, FIG. 8 shows, for comparison, (c) change in power generation performance with time when 100% biomethanol fuel not containing fossil fuel methanol is used (that is, DMFC type fuel cell 200 shown in FIG. 6). At the same time.

  As these fuels, a mixture of biomethanol and fossil fuel methanol (or biomethanol alone in the case of (c)) was diluted with pure water and used as an aqueous methanol solution having a concentration of 60%.

  FIG. 8 shows that the decreasing rate of the maximum power generation density peak decreases as the order of (c), (b), and (a) increases, that is, as the concentration of fossil fuel methanol in the fuel increases.

  Thus, it was confirmed that deterioration of the characteristics of the fuel cell can be suppressed by using a mixed methanol of biomethanol and fossil fuel methanol as the fuel.

  Here, increasing the ratio of fossil fuel methanol in the fuel leads to a decrease in the utilization rate of biomethanol. This also seems to deviate from the perspective of promoting the use of biomethanol, a renewable fuel.

  However, even when using a mixed fuel of biomethanol and fossil fuel methanol as described above, compared to the conventional case of using 100% fossil fuel methanol as a fuel, from the viewpoint of global environmental protection and the like. It can be said that the conversion of renewable energy is being promoted.

  Further, in order to suppress the proportion of fossil fuel methanol in the fuel as much as possible and increase the amount of biomethanol used, the performance degradation behavior of the fuel cell may be grasped, and the power generation amount may be set based on this.

  For example, the power density of the fuel cell after elapse of a predetermined time (for example, 1000 hours) from the performance deterioration curve (for example, the curve (b) of FIG. 8) when the mixing ratio of biomethanol and fossil fuel methanol is 50:50 Predict the value.

  Here, when the predicted power density value after a predetermined time is predicted to be lower than the target value, the power generation area (area of the electrolyte membrane) of the fuel cell is set large in advance. Since the power density value is proportional to the power generation area (area of the electrolyte membrane), this correspondence enables the power density value of the fuel cell after a predetermined time to exceed the target value.

  On the other hand, when it is predicted that the predicted power density value of the fuel cell after the predetermined time has already exceeded the target value, the same examination may be performed by further increasing the mixing ratio of biomethanol. Such measures can increase the amount of biomethanol used in the fuel as much as possible.

  In the example of FIG. 7, the activated carbon 212 is installed in the fuel tank 111, but this is not always necessary, and the activated carbon 212 may not be installed in the fuel tank 111. Will be apparent to those skilled in the art.

(About cleaning the activated carbon layer)
As described above, the DMFC type fuel cell according to the present invention has the feature of having the activated carbon layer 150.

  Here, if the usage time is prolonged and the amount of the sulfur component adsorbed on the activated carbon layer 150 is increased, the impurity removing ability of the activated carbon layer 150 may be reduced. Therefore, in order to recover the impurity removal capability of the activated carbon layer 150, it is preferable to occasionally clean the activated carbon layer 150.

  Therefore, an example of a method for cleaning the activated carbon layer 150 will be described below.

  FIG. 9 shows a cleaning method of the activated carbon layer used in the DMFC type fuel cell according to the present invention. 9 exemplifies the fuel cell 100 of the type shown in FIG. 2 as a DMFC type fuel cell having the activated carbon layer 150. However, the DMFC type fuel cell may be of another type, for example, a DMFC type fuel cell. The batteries 200 and 300 may be used.

  In order to clean the activated carbon layer 150, first, warm water is introduced into the fuel cell main body 130 using the fuel flow path of the fuel cell main body 130. The hot water may be introduced, for example, through the fuel inlet 120a of the fuel cell main body 130. The temperature of the hot water is not particularly limited, but is preferably 90 ° C. or lower. This is for reliably preventing damage to the electrolyte membrane 170.

  When the hot water reaches the activated carbon layer 150, the activated carbon 152 in which impurities are adsorbed is immersed in the hot water, and the temperature of the activated carbon 152 rises. In general, the activated carbon 152 easily releases adsorbed impurities as the temperature rises. Accordingly, the impurities adhering to the activated carbon 152 are desorbed in the warm water.

  Thereafter, the hot water containing desorbed impurities is discharged to the outside through the discharge port 920a provided at an appropriate location of the fuel cell main body 130. Thereby, impurities can be removed from the activated carbon 152 and the activated carbon 152 can be cleaned.

  After the activated carbon 152 is washed with warm water, it is preferable to sufficiently remove the warm water remaining in the fuel flow passage before power generation of the fuel cell again. Thereby, it is possible to prevent the methanol concentration from decreasing when the fuel is reintroduced. The removal of warm water may be performed by introducing air (hot air or the like), for example.

  FIG. 10 shows an example of the cleaning effect of activated carbon.

  Fig. 10 shows the change over time in power generation characteristics (maximum power generation density peak) when a DMFC type fuel cell is continuously operated for 1000 hours, then the operation is stopped, the activated carbon is cleaned with warm water, and then the fuel cell is operated again. It is the graph which showed continuously.

  As the DMFC type fuel cell, the type shown in FIG. 2 was used. Moreover, 100% biomethanol was used as the fuel. The cleaning of the activated carbon was performed by continuously introducing 80 ° C. warm water (pure water) from the fuel inlet of the fuel cell main body for 10 minutes, and washing the activated carbon.

  FIG. 10 shows that the power generation performance of the fuel cell is improved after cleaning the activated carbon (immediately after the time point described as “refresh”). Thus, it was confirmed that cleaning of activated carbon after use restored the impurity removal effect of activated carbon and improved the power generation performance of the fuel cell again.

  In the above example, warm water is used for cleaning the activated carbon, but a liquid or gas other than warm water may be used for this purpose as long as there is no risk of damaging the members constituting the fuel cell.

  FIG. 11 shows an example in which a gas is used for cleaning the activated carbon.

  In this case, unlike the case of FIG. 9, hot air is used for cleaning the activated carbon 152. That is, in this example, warm air is introduced into the fuel cell main body 130 through the fuel intake port 120a. The temperature of the hot air is preferably 90 ° C. or lower for the above-described reason.

  In this method, the activated carbon 152 is heated with warm air, and the components adsorbed on the activated carbon 152 are desorbed into the warm air. Therefore, the activated carbon 152 can be cleaned also by such a method.

  FIG. 12 shows an example of the cleaning effect of activated carbon by hot air.

  FIG. 12 shows the time lapse of power generation characteristics (maximum power generation density peak) when the DMFC type fuel cell was continuously operated for 1000 hours, the operation was stopped, the activated carbon was cleaned with warm air, and then the fuel cell was operated again. It is the graph which showed the change continuously.

  As the DMFC type fuel cell, the type shown in FIG. 2 was used. Moreover, 100% biomethanol was used as the fuel. The cleaning of the activated carbon was performed by continuously introducing warm air of 80 ° C. for 10 minutes from the fuel intake port of the fuel cell main body and washing the activated carbon.

  From FIG. 12, it can be seen that in this case as well, the power generation performance of the fuel cell is improved after cleaning the activated carbon (immediately after the time point described as “refresh”).

  From the comparison between FIG. 10 and FIG. 12, it is expected that cleaning with warm water is more effective in cleaning with warm water and cleaning with warm air.

However, in the case of cleaning with warm water, it is necessary to prepare peripheral equipment such as preparation of warm water and installation of piping. On the other hand, cleaning with warm air can be performed relatively easily using a simple blower (dryer) or the like. For this reason, when a general user cleans activated carbon, cleaning with warm air is considered significant.

  Of course, cleaning with warm water and cleaning with warm air may be used in combination.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fuel cell used for information devices such as portable devices and home appliances, particularly a DMFC type fuel cell using methanol as a fuel (Direct Methanol Fuel Cell).

DESCRIPTION OF SYMBOLS 10 Conventional DMFC type fuel cell 11 Fuel tank 20a Fuel inlet 20b Air inlet 25 External load 30 Fuel cell body 40 Methanol layer 60 Negative electrode (fuel electrode)
60A negative electrode catalyst layer 70 electrolyte membrane 80 positive electrode catalyst layer 80A positive electrode catalyst layer 90 air layer 100 DMFC type fuel cell 111 according to the present invention 111 fuel tank 120a fuel intake port 120b air intake port 130 fuel cell main body 140 methanol layer 150 activated carbon layer 152 activated carbon 160 Negative electrode 160A Negative electrode catalyst layer 170 Electrolyte membrane 180 Positive electrode 180A Positive electrode catalyst layer 190 Air layer 200 DMFC fuel cell 212 activated carbon according to the present invention 300 DMFC fuel cell according to the present invention 362 Catalyst particles 363 Carbon particles 462 Catalyst particles 463 Carbon particles 920a Discharge port

Claims (7)

A DMFC type fuel cell having a negative electrode, a positive electrode, and an electrolyte layer disposed between the two electrodes,
The DMFC type fuel cell uses biomethanol as fuel,
The fuel is supplied from a biomethanol source to the negative electrode through a flow passage connected to the biomethanol source and the negative electrode,
A DMFC type fuel cell, wherein an activated carbon layer having activated carbon is provided in at least a part of the flow passage.   2. The DMFC fuel cell according to claim 1, wherein the activated carbon layer is disposed adjacent to the negative electrode on a side opposite to the electrolyte layer of the negative electrode. Furthermore, it has a fuel tank as the biomethanol source,
The DMFC fuel cell according to claim 1 or 2, wherein a second activated carbon is installed in the fuel tank.   The DMFC type fuel cell according to any one of claims 1 to 3, wherein a mixture of biomethanol and methanol produced from fossil fuel is used as the fuel.   The DMFC type fuel cell according to any one of claims 1 to 4, further comprising means for cleaning the activated carbon of the activated carbon layer.   5. The DMFC-type fuel according to claim 1, wherein the flow passage includes a fluid introduction port for cleaning the activated carbon of the activated carbon layer and a discharge port for the fluid. battery.   The DMFC type fuel cell according to claim 6, wherein the fluid for cleaning the activated carbon of the activated carbon layer is hot water and / or hot air.

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