JP2953464B1 - Humidity regulator - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To improve the dehumidifying performance without dangerous accumulation of hydrogen by increasing the binding ability of hydrogen ions and oxygen on the cathode side, and to adjust humidity with less performance deterioration due to aging. Get a bowl. SOLUTION: A solid electrolyte membrane 10 having cationic conductivity,
The solid electrolyte membrane 10 is provided on the surface of the cathode 13 side, and the amount of platinum group metal or platinum group metal oxide is 0.3 mg /
a first cathode catalyst layer 11a set in the range of cm ^{2 to 3} mg / cm ^2, a first porous substrate 12 provided in contact with the first cathode catalyst layer 11a, is formed in the bonding side of the above first cathode catalyst layer 11a of the substrate 12, the range the amount of the fine particles of platinum group metal or platinum group metal oxide of 0.3mg / cm ² ~3mg / cm ² The dispersed second cathode catalyst layer 11b and the second porous substrate 1 bonded to the surface of the solid electrolyte membrane 10 on the anode 16 side
4 was provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a humidity controller using an ionic conductive solid electrolytic device.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of a conventional humidity controller using a solid electrolytic device disclosed in Japanese Patent Application Laid-Open No. 6-63343. In the figure, 1 is a cation conductive solid polymer electrolyte layer, 2 and 3 are porous substrates,
It is formed of a woven or nonwoven fabric of metal fibers, a sintered body of metal powder, a carbon fiber material, a metal perforated plate, or the like. 4
And 5 are catalyst layers. A paste containing platinum black is applied to the porous substrates 2 and 3, and the solid polymer electrolyte layer 1 is sandwiched and hot-pressed. Carbon and the like are formed three-dimensionally distributed. Further, the porous substrate 2 and the catalyst layer 4 are
And the porous substrate 3 and the catalyst layer 5 form the cathode 7. Reference numeral 8 denotes a DC power supply, and 9 denotes a dehumidification chamber provided on the anode 6 side.

In the conventional humidity controller constructed as described above, when power is supplied from the DC power supply 8 between the anode 6 and the cathode 7, the moisture in the dehumidification chamber 9 is reduced to ( Electrolysis is performed by the reaction of the formula 1), and oxygen is supplied into the dehumidification target chamber 9 and moisture is removed. As the electrons e reach the cathode 7, the electrons e reach the cathode 7 through an external circuit including a DC power supply 8, and generate water while consuming oxygen on the cathode 7 side by the reaction of the following formula (2). Since it moves from the pole 6 side to the cathode 7 side, the dehumidification of the dehumidification chamber 9 is promoted on the anode 6 side.

[0004]

In the conventional humidity controller using the ionic conductive solid electrolytic device constructed as described above, the reaction of the above formula (1) increases with the voltage value of the DC power supply 8. Therefore, the performance of the humidity controller is improved by increasing the applied voltage. However, when hydrogen ions generated at the cathode 7 increase with the applied voltage and the voltage exceeding the oxidizing ability on the cathode 7 side is applied, In this method, water generated by oxidation could not be followed, and hydrogen gas was accumulated on the cathode 7 side, causing a risk of causing a hydrogen explosion. In order to avoid this accumulation of hydrogen gas, in the conventional humidity controller, it was necessary to suppress the applied voltage to a certain voltage or less. However, the suppression of the applied voltage imposes restrictions on the dehumidifying ability. Could not be sufficiently enhanced.

In order to avoid such a restriction, for example, in Japanese Patent Application Laid-Open No. 9-157876, a gas-permeable water conversion film is laminated in close contact with the cathode electrode surface, and the water conversion film is used as an oxidation catalyst. A configuration is disclosed in which a hydrogen ion conductive porous base material carrying platinum fine particles is used to improve the hydrogen ion oxidizing ability. According to this technology, since the catalyst layer made of platinum fine particles is closely stacked on the cathode, the bond between hydrogen ions and oxygen is promoted, and there is an effect of suppressing the accumulation of hydrogen gas. There is a quantitative limit on the bond between ions and oxygen,
There has been a limit in improving the performance of the humidity controller while suppressing the accumulation of hydrogen gas. In addition, the catalyst layer formed at the junction between the porous substrate on the anode side and the cathode side and the solid polymer electrolyte layer deteriorates the electric bonding force with the solid polymer electrolyte layer with use time, and has a dehumidifying ability. Has a problem in that it decreases in a relatively short time.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and by increasing the binding ability between hydrogen ions and oxygen on the cathode side, high dehumidification performance without dangerous accumulation of hydrogen. Further, it is an object of the present invention to obtain a humidity controller with which the performance is not greatly deteriorated due to aging.

[0007]

SUMMARY OF THE INVENTION A humidity controller according to the present invention is provided on a cation-conductive solid electrolyte membrane and a cathode-side surface of the solid electrolyte membrane, and comprises a platinum group metal or a platinum group metal oxide. the amount of things 0.3mg / cm ² ~3mg / c
a first cathode catalyst layer is set in the range of m ^2, a first porous substrate provided in contact with the first cathode catalyst layer,
The first porous substrate is in the form on the bonding side of the first cathode catalyst layer described above, the amount of fine particles of platinum group metal or platinum group metal oxide is 0.3mg / cm ² ~3mg / cm ² And a second porous substrate bonded to the anode-side surface of the solid electrolyte membrane.

[0008] The second porous anode side of the outer surface of the solid electrolyte membrane includes an outer surface of the base material, the amount of platinum group metal or platinum group metal oxide is 0.3mg / cm ² ~3mg / cm ²
Is provided with an anode catalyst layer set in the range described above. Further, a first porous substrate having a second cathode catalyst layer, and a solid electrolyte membrane having a first cathode catalyst layer,
The second porous substrate is physically and electrically joined by hot pressing. Still further, the second cathode catalyst layer formed on the first porous substrate is set to have a depth of 20 μm to 100 μm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 relates to a humidity controller according to Embodiment 1 of the present invention, and in particular, is a cross-sectional view showing a configuration of an electrochemical element section, and FIGS. 2 to 5 are operating characteristic diagrams thereof. In the figure, reference numeral 10 denotes a solid electrolyte membrane having a thickness of about 170 μm using a cation-conductive solid polymer electrolyte, such as Nafion-117 (D
u Pont (registered trademark NAFION) or the like is used. Reference numeral 11a denotes a first cathode catalyst layer formed on the surface of the solid electrolyte membrane 10 on the cathode side. Platinum black is mixed with a volatile solvent such as isopropyl alcohol and water so that the amount of platinum black is 0.1%.
It is formed by spraying a solid electrolyte membrane 10 to have a thickness of ^{3mg / cm 2 ~3mg / cm 2} . Reference numeral 12 denotes a first porous substrate having a thickness of about 200 μm, which is formed of carbon fibers such as carbon paper and carbon cloth, and has a depth of 20 μm to 10
In the range of 0 μm, platinum fine particles contained 0.3 mg / cm of platinum.
The second cathode catalyst layer 11b is formed by being dispersed in the range of ^{2 to 3} mg / cm ² , and the first cathode catalyst layer 11a
And the second cathode catalyst layer 11b form the cathode 13.

Reference numeral 14 denotes a solid electrolyte membrane 10 provided on the anode side and having a thickness of about 10
A second porous substrate having a water permeability of 0 μm, and a second porous substrate 14 and a first porous substrate 12 on which the second cathode catalyst layer 11b is formed. The solid electrolyte membrane 10 on which one cathode catalyst layer 11a is formed is sandwiched and hot-pressed at a temperature of about 180 ° C. and a pressure of about 50 kg / cm ² to physically integrate them and electrically bond them. doing. Reference numeral 15 denotes an anode catalyst layer formed on the anode side. After the first porous layer 12, the solid electrolyte membrane 10, and the second porous layer 14 are electrically joined by hot pressing, isopropyl alcohol and water Platinum black is mixed with a volatile solvent such as, and the amount of platinum black is 0.3 mg / cm.
^The solid electrolyte membrane 10 and the second porous layer 14 are formed by coating or spraying on the air side so as to have a thickness of ^{2 to 3} mg / cm ² , and the second porous layer 14 and the anode catalyst layer 15 Thus, the anode 16 is formed. 17 is the cathode 1
DC power supply connected between the power supply 3 and the anode 16. Further, as a catalyst for forming the cathode catalyst layer and the anode catalyst layer, a platinum group metal such as platinum-supported carbon, ruthenium, iridium, and palladium, or an oxide thereof can be used in addition to platinum.

In the humidity controller according to the first embodiment of the present invention, when a voltage is applied from the DC power supply 17 between the cathode 13 and the anode 16, the above-described conventional example is applied to the anode 16 side. The water is electrolyzed by the same reaction as in the formula (1) shown in the above, and the humidity in the dehumidifying space is reduced. On the cathode 13 side, water is generated by the same reaction as in the above-mentioned conventional example (2), and 1 to 3 water molecules move from the anode 16 side to the cathode 13 side through the solid electrolyte membrane 10 to dehumidify. Is promoted. Hydrogen ions passing through the solid electrolyte membrane 10 from the anode 16 side to the cathode 13 side are first oxidized by the first cathode catalyst layer 11a to generate water, and are not oxidized by the first cathode catalyst layer 11a. The hydrogen ions pass through the second cathode catalyst layer 11b, and are further oxidized by the reaction of the following formula (3), and are almost completely converted into water.

FIG. 2 is a graph showing the voltage-current versus the amount of platinum black in the catalyst layer under the conditions that the effective area of the solid electrolyte membrane 10 is 100 cm ² , the temperature of the atmosphere is 30 ° C., and the relative humidity is 60%. FIG. 4 is a characteristic diagram. In characteristic I, the amount of platinum black is 1 mg / mg.
In the case of cm ² , the characteristic II shows the characteristic at 0.3 mg / cm ² , and the characteristic III shows the characteristic at 3 mg / cm ² . Thus, when the amount of platinum black is 1 mg / cm ² , the applied voltage is 3 V, the current is almost saturated at 4 A, and when the amount of platinum black is 0.3 mg / cm ² , the solid electrolyte membrane accompanying the increase in the electric resistance of the catalyst layer The saturation current decreases due to the effect of the voltage drop on the value of 10, and at 3 mg / cm ² , the saturation current increases due to the decrease in the electrical resistance of the catalyst layer.

FIG. 3 shows the relationship between the amount of platinum black in the catalyst layer, the current flowing through the solid electrolyte membrane 10, and the conditions of the atmosphere. %, The characteristic II indicates a case where the atmospheric temperature as an average throughout the year is 15 ° C. to 20 ° C. and the relative humidity is 60%. As is clear from this characteristic diagram, when the ambient temperature is 30 ° C., the amount of platinum black in the catalyst layer is 3%.
The amount of current saturates around mg / cm ² , and the dehumidifying capacity proportional to the amount of current saturates when the amount of platinum black is 3 mg / cm ² .
In addition, in the case of the characteristic II, which is an average condition for the year, the characteristic is saturated when the amount of platinum black is 1 mg / cm ² , and even if the amount of platinum black is reduced to 0.3 mg / cm ^{2, the} characteristic does not decrease. It is about 25% of the saturation point, and the amount of platinum black is 0.3 mg / cm ²
Below, the characteristics sharply decrease. Therefore, in terms of performance, the amount of platinum black in the catalyst layer is reduced from 0.3 mg / cm ² to 3 mg / c.
It can be determined that setting m ² is effective.

FIG. 4 is a characteristic diagram showing how the performance of the humidity controller according to the present invention and the conventional example deteriorate over time. The conventional example here is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-216714. A cathode and an anode are provided on both sides of a cation exchange membrane, a mixture containing platinum-supported carbon powder is bonded to the cation exchange membrane by hot pressing on the cathode, and the anode is made of platinum by electroless plating. It is bonded to an ion exchange membrane. As shown in FIG. 4, in the results of the accelerated deterioration test, there is a remarkable difference in deterioration between the humidity controller according to the present invention and the conventional example. Porous layer 14 and solid electrolyte membrane 10
Are electrically bonded by hot pressing, and then the anode catalyst layer 15 is provided on the outer surface of the solid electrolyte membrane 10 including the outer surface of the second porous layer 14, so that the anode 16 and the solid electrolyte membrane 10 Is suppressed, and the catalyst layer on the cathode side is composed of the first cathode catalyst layer 11a and the second cathode catalyst layer 11b. This is because it leads to suppression.

FIG. 5 shows the concentration of hydrogen generated and accumulated on the cathode side 13 of the humidity controller according to the present invention.
This is a comparison based on the presence or absence of 1b. As is apparent from the figure, when there is no second cathode catalyst layer 11b, that is, when there is no dispersion of platinum in the first porous base material 12 on the cathode side, the hydrogen concentration rises rapidly with the test time. The porous substrate 12 has at least a depth of 20 μm and a platinum amount of 0.3 mg /
It can be seen that if there is a dispersion of cm ^2, the hydrogen concentration is suppressed. The suppression of hydrogen generation on the cathode 13 side prevents the hydrogen 13 from drying due to the hydrogen gas at the interface between the cathode 13 and the solid electrolyte membrane 10 together with the effect of preventing hydrogen explosion.
This leads to suppression of joint deterioration due to drying of the interface with 0, and further enhances the effect of preventing deterioration with time described with reference to FIG. The above is the first porous substrate 1 on the cathode 13 side.
Although 2 is described as a carbon fiber material, a similar effect can be obtained by using a paper made of stainless steel fiber, for example, a stainless steel web sintered body manufactured by Nippon Seisen Co., Ltd.

[0016]

As described above, according to the humidity controller of the present invention, the first cathode catalyst layer made of a platinum group metal or a platinum group metal oxide for accelerating the cathode reaction is provided on the cathode side. A platinum amount of 0.3 mg / cm ² to 3 mg / cm ² was formed, and the second cathode catalyst layer was formed with a platinum amount of 0.3 mg / cm ^2.
The solid electrolyte membrane 10 is formed at a depth of 20 μm to 100 μm on the first porous base material at a concentration of ² mg / cm ² to 3 mg / cm ^2, and includes the outer surface of the second porous layer 14 on the anode side.
Since the anode catalyst layer 15 is formed on the outer surface with a platinum amount of 0.3 mg / cm ² to 3 mg / cm ² , generation of hydrogen on the cathode side can be effectively suppressed, and danger such as hydrogen explosion can be reduced. In addition to being able to remove completely, the applied voltage can be increased to near the saturation point of the dehumidifying ability to enhance the dehumidifying performance. This makes it possible to obtain a high-performance, long-life humidity controller.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a humidity controller according to Embodiment 1 of the present invention.

FIG. 2 is an operation characteristic diagram of the humidity controller according to Embodiment 1 of the present invention.

FIG. 3 is an operation characteristic diagram of the humidity controller according to Embodiment 1 of the present invention.

FIG. 4 is an operation characteristic diagram of the humidity controller according to Embodiment 1 of the present invention.

FIG. 5 is an operation characteristic diagram of the humidity controller according to Embodiment 1 of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a conventional humidity controller.

[Explanation of symbols]

Reference Signs List 10 solid electrolyte membrane, 11a first cathode catalyst layer, 11
b second cathode catalyst layer, 12 first porous substrate, 1
3 cathode, 14 second porous substrate, 15 anode catalyst layer, 16 anode, 17 DC power supply.

Continuation of the front page (72) Inventor Takeaki Hanada 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi, Hyogo Rishi-ai-Technica Co., Ltd. (56) References JP-A-9-155157 (JP, A) JP-A-9- 316675 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01D 53/26 B01D 53/32 C25B 1/00-1/46 C25B 11/00-11/20

Claims (4)

(57) [Claims] 1. A cation-conductive solid electrolyte membrane, provided on a surface of the solid electrolyte membrane on the cathode side, wherein the amount of platinum group metal or platinum group metal oxide is 0.3 mg / cm ^{2 to} 3 mg.
/ First cathode catalyst layer set in the range of / cm ^2, a first porous substrate provided in contact with the first cathode catalyst layer,
The amount of the fine particles of the platinum group metal or the platinum group metal oxide formed on the side of the first porous substrate joined to the first cathode catalyst layer is 0.3 mg / cm ^{2 to} 3 mg / cm ² . A humidity controller comprising: a second cathode catalyst layer dispersed in a range; and a second porous base material bonded to an anode-side surface of the solid electrolyte membrane. 2. A second anode side of the outer surface of the solid electrolyte membrane includes an outer surface of the porous substrate, the amount of platinum group metal or platinum group metal oxide is 0.3mg / cm ² ~3mg / cm ² The humidity controller according to claim 1, further comprising an anode catalyst layer set in the range of: 3. The first porous substrate having the second cathode catalyst layer, the solid electrolyte membrane having the first cathode catalyst layer, and the second porous substrate are physically and hot-pressed. The humidity controller according to claim 1, wherein the humidity controller is electrically connected. 4. The method according to claim 1, wherein the second cathode catalyst layer formed on the first porous substrate has a depth in a range of 20 μm to 100 μm. 1
The humidity controller according to the item.