Hydrogen gas concentration sensor

Abstract

The present invention comprises a first electrode piece, a second electrode piece, an electrolyte in which the electrode pieces are disposed apart from each other, and a container which accommodates the first electrode piece, the second electrode piece, and the electrolyte, wherein: the first electrode piece includes a first electrode material exhibiting a standard electromotive force value of at least 0.8 V in a cell configured from H2 (-), 50 mol / m3 of H2SO4, and a substance sample (+); the second electrode includes a second electrode material exhibiting a standard electromotive force value of less than 0.8 V in a cell having the same configuration; and the first electrode piece penetrates through the electrolyte and has an end that is externally exposed from the container.

Description

Technical Field

[0001] The present invention relates to a hydrogen gas concentration sensor.

Background Art

[0002] In the future hydrogen energy utilization society, it is desired to construct a hydrogen energy utilization system with high safety and excellent convenience by eliminating the risk of hydrogen explosion. The specifications of the hydrogen gas sensor are required to be able to instantaneously and highly accurately detect the amount of hydrogen leaked into the atmosphere, and have an extremely simple structure and high reliability.

[0003] On the other hand, development of hydrogen concentration sensors for control of hydrogen fuel cells (efficient utilization of hydrogen gas) in automobiles and heavy machinery, hydrogen concentration sensors for liquids such as lubricating oil and transformer oil for generator shafts (detection of the amount of hydrogen gas dissolved in oil and the amount of hydrogen gas due to oil deterioration), hydrogen concentration sensors in medical chemical solutions such as kidney dialysis (promoting the therapeutic effect by dissolving hydrogen), hydrogen concentration sensors in solutions such as hydrogen water, and hydrogen concentration sensors for process control in the chemical industry, etc. is desired.

[0004] Conventional hydrogen gas concentration sensors are based on detection methods such as semiconductor type, ionization type, and combustion type. These measurement principles detect the amount of hydrogen indirectly as "carrier concentration (semiconductor type)", "ion concentration (ionization type)", or "heat of reaction (combustion type or measuring the vapor pressure of the combustion product)", which are "quantitative physical quantities", and convert them into electrical quantities to form sensors.

[0005] Therefore, it is impossible to detect hydrogen concentration in a high-temperature and high-humidity environment or apply it to liquids such as oil and chemical solutions. Naturally, it was impossible to apply it to the detection of the concentration of hydrogen gas dissolved in these liquids.

[0006] As a hydrogen gas concentration sensor that shortens the detection time, for example, a hydrogen gas sensor has been proposed that includes a first electrode and a second electrode made of materials with different chemical potentials for hydrogen, and an electrolyte in contact with these electrodes, and detects hydrogen gas based on the electromotive force value generated between these electrodes (Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 4035848 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the hydrogen gas sensor described in Patent Document 1, the first electrode, second electrode, and electrolyte are covered by an outer shell. Therefore, in order to measure the dissolved hydrogen gas concentration in a liquid, at least the first electrode, which is the detection electrode, must be exposed from the outer shell and immersed in the liquid, while the electrolyte must be sealed away from the liquid. Consequently, the structure of the hydrogen gas sensor becomes complex, and there are technical and economic challenges in the sealing method.

[0009] The present invention aims to provide a novel hydrogen gas concentration sensor capable of detecting the concentration of hydrogen gas present in environments such as special gases and liquids in chemical industries, under high temperature and high humidity conditions. [Means for solving the problem]

[0010] The present invention is as follows: (1) A first electrode piece and a second electrode piece, an electrolyte in which these electrode pieces are arranged separately, and a container for housing the first electrode piece, the second electrode piece and the electrolyte, wherein the first electrode piece is H2(-)|50mol / m³ 3A hydrogen gas concentration sensor comprising a first electrode material that exhibits a standard electromotive force value of 0.8V or higher for a cell composed of H2SO4|material sample (+), a second electrode material that exhibits a standard electromotive force value of less than 0.8V for a cell with the same configuration, and the first electrode piece penetrating the solid electrolyte with its end exposed to the outside of the container. (2) The hydrogen gas concentration sensor according to (1), characterized in that the first electrode material comprises at least one of platinum, platinum alloys, and materials containing these. (3) The hydrogen gas concentration sensor according to (1), characterized in that the first electrode material comprises at least one of palladium, a palladium alloy, and a material containing these. (4) The hydrogen gas concentration sensor according to any one of (1) to (3), characterized in that the second electrode material comprises at least one of tungsten, tungsten alloy, nickel, nickel alloy, titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy, and materials containing these. (5) A hydrogen gas concentration sensor according to any one of (1) to (4), characterized in that it comprises a third electrode piece for temperature compensation housed in the container and disposed in the electrolyte. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a hydrogen gas concentration sensor with a novel configuration that can detect the concentration of hydrogen gas present in special gases or liquids used in the chemical industry, etc., under high temperature and high humidity conditions. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of the hydrogen gas concentration sensor in an embodiment. [Figure 2] This graph shows the EMF values ​​when a platinum wire is used as the first electrode piece of the hydrogen gas concentration sensor in the example. [Figure 3] This graph shows the EMF values ​​when a palladium wire is used as the first electrode piece of the hydrogen gas concentration sensor in the example. [Figure 4] It is a graph showing the hydrogen gas concentration and the EMF value when a platinum wire is used as the first electrode piece of the hydrogen gas concentration sensor in the embodiment. [Figure 5] It is a graph showing the relationship between the hydrogen gas concentration and the EMF value when a palladium wire is used as the first electrode piece of the hydrogen gas concentration sensor in the embodiment.

Embodiments for Carrying Out the Invention

[0013] FIG. 1 is a schematic configuration diagram of the hydrogen gas concentration sensor in the present embodiment.

[0014] As shown in FIG. 1, the hydrogen gas concentration sensor 10 of the present embodiment includes a linear first electrode piece 11 and a linear second electrode piece 12, an electrolyte 14 in which these electrode pieces are disposed apart from each other, and a container 15 with one end sealed that houses the first electrode piece 11, the second electrode piece 12, and the electrolyte 14.

[0015] Note that the container 15 is inserted and disposed in the system whose tip is to be measured. Therefore, although the inside of the container 15 is gas-insulated from the system to be measured, it is desirable to seal the inside so as not to be affected by humidity or the like from the outside.

[0016] Further, since the first electrode piece 11 functions as a hydrogen gas detection electrode, its tip penetrates the sealed portion of the electrolyte 14 and is exposed outside the container 15. Note that the penetrating portion of the first electrode piece 11 through the container 15 is melt-sealed.

[0017] However, as will be described below, the second electrode piece 12 is composed of a material with a relatively low chemical potential and does not affect the detection of hydrogen gas. Therefore, the end of the second electrode piece 12 can also be exposed to the outside from the sealed portion of the container 15 in the same manner as the first electrode piece 11. However, generally, re-melt sealing is required, and the configuration and manufacturing process of the hydrogen gas concentration sensor 10 become complicated. Therefore, it is preferable not to expose it outside the container 15.

[0018] In addition, since the detection sensitivity of the hydrogen gas concentration sensor 10 of the present embodiment changes depending on the ambient temperature, a linear third electrode piece 13 for temperature compensation is provided to eliminate the influence of the ambient temperature. This third electrode piece 13 is also arranged so as to be separated from the first electrode piece 11 and the second electrode piece 12 with respect to the electrolyte 14.

[0019] In addition, the first electrode piece 11, the second electrode piece 12, and the third electrode piece 13 are arranged so as to extend outside the container 15 from the rear end opening of the container 15 on the side opposite to the sealed portion of the container 15 in order to measure the electromotive force associated with the detection of the hydrogen gas concentration.

[0020] The first electrode piece 11 functions as a detection electrode for hydrogen gas, and when it comes into contact with hydrogen gas, the chemical potential of (atomic) hydrogen changes significantly. The second electrode piece 12 functions as a reference electrode for hydrogen gas, and when it comes into contact with hydrogen gas, its chemical potential hardly changes or, if it does change, the change is extremely small.

[0021] The first electrode piece 11 can be composed of a first electrode material having a relatively high chemical potential. Specifically, it includes a first electrode material for which the standard electromotive force value of a cell composed of H2( - )|50mol / m 3 H2SO4|substance sample( + ) shows a value of 0.8V or more.

[0022] Examples of the above-described materials include materials such as platinum and platinum alloys that have a relatively high adsorption activity with respect to hydrogen gas. The first electrode piece 11 can be composed of these materials themselves, but these materials can also be supported on a predetermined substrate and used. However, as long as it functions as a detection electrode for hydrogen gas without departing from the scope of the present invention, it can be used in any manner.

[0023] Furthermore, the materials mentioned above can also be composed of materials with relatively high adsorption activity for hydrogen gas, such as palladium and palladium alloys. Similarly, the first electrode piece 11 can be composed of these materials themselves, or these materials can be supported on a predetermined substrate. However, as long as it does not deviate from the scope of the present invention and functions as a detection electrode for hydrogen gas, it can be used in any manner.

[0024] Furthermore, if the first electrode piece 11 is made of a platinum-based material, hydrogen molecules are dissociated, resulting in rapid detachment of hydrogen gas adsorbed on the first electrode piece 11. This makes it suitable as a detection electrode for a highly responsive hydrogen gas concentration sensor, such as a control sensor for fuel cells or a hydrogen gas concentration sensor for dissolved hydrogen gas in medical solutions.

[0025] On the other hand, when the first electrode piece 11 is made of a palladium-based material, it dissolves a quantity of hydrogen corresponding to the partial pressure of hydrogen, but the dissolved hydrogen has the property of being difficult to escape, and recovery after hydrogen gas detection takes time. Therefore, when the first electrode piece 11 is made of a palladium-based material, the first electrode piece 11 has a memory function and can be applied as a detection electrode suitable for, for example, checking the deterioration of transformer oil.

[0026] The second electrode piece 12 can be made from a material with a relatively low chemical potential, specifically H2(-)|50 mol / m³ 3 The second electrode material includes a cell composed of H2SO4|material sample (+) exhibiting a standard electromotive force value of less than 0.8V.

[0027] The materials mentioned above include tungsten, tungsten alloys, nickel, nickel alloys, titanium, titanium alloys, copper, copper alloys, iron, iron alloys, aluminum, aluminum alloys, and organic conductive materials, which are materials with relatively low adsorption activity to hydrogen gas. However, they can be used in any form as long as they function as a reference electrode for hydrogen gas without departing from the scope of the present invention.

[0028] Furthermore, the third electrode piece 13 is an electrode piece for temperature compensation and is installed to compensate for changes in the ambient temperature of the hydrogen gas concentration sensor 10, i.e., the ambient temperature of the first electrode piece 11, which is the detection electrode. Therefore, it is preferable that it be made of the same material as the first electrode piece 11.

[0029] Furthermore, the electrolyte 14 can be composed of an electrolyte with excellent adhesion to the first electrode 21 and the second electrode 22, such as phosphotungstic acid. In addition to the electrolyte material such as phosphotungsten, the electrolyte 14 may include structural reinforcing materials such as glass wool. In this case, the strength of the electrolyte 14 can be increased, and the adhesion to the first electrode piece 11 and the second electrode piece 12 can be further increased.

[0030] The container 15 is preferably made of glass, resin, ceramics, or the like to ensure insulation from the first electrode piece 11 and the second electrode piece 12.

[0031] Furthermore, if the container 15 is made of an electrically conductive material such as metal, it is preferable to insulate the first electrode piece 11 from the container 15 by coating it with resin or ceramic.

[0032] The hydrogen gas concentration sensor 10 of this embodiment comprises a first electrode piece 11 and a second electrode piece 12, an electrolyte 14 in which these electrode pieces are arranged separately, and a container 15 that houses the first electrode piece 11, the second electrode piece 12, and the electrolyte 14, wherein the first electrode piece 11 contains H2(-)|50mol / m³ 3 The first electrode piece 11 includes a first electrode material that exhibits a standard electromotive force value of 0.8V or higher in a cell composed of H2SO4|material sample (+), the second electrode piece 12 includes a second electrode material that exhibits a standard electromotive force value of less than 0.8V in a cell with the same configuration, and the first electrode piece 11 penetrates the electrolyte 14, with its end exposed to the outside from the container 15.

[0033] Therefore, in order to detect the dissolved hydrogen gas concentration, the first electrode piece 11 exposed from the container 15 of the hydrogen gas concentration sensor 10 should be immersed in the liquid containing dissolved hydrogen gas. In this case, even if the tip of the container 15 is immersed in the liquid, the electrolyte 14 itself is contained within the container 15 and sealed, so it is not immersed in the liquid. In other words, the hydrogen gas concentration sensor 10 can detect the hydrogen gas concentration dissolved in the liquid using the first electrode piece 11, which is the detection electrode immersed in the liquid, and the second electrode piece 12, which is the reference electrode. Similarly, it can detect the hydrogen gas concentration in high-temperature, high-humidity environments and in special gases such as those used in the chemical industry.

[0034] Thus, with the hydrogen gas concentration sensor 10 of this embodiment, it is sufficient to immerse its tip in the liquid and the first electrode piece 11, which is the detection electrode, in the liquid. Therefore, unlike conventional sealed-type hydrogen gas concentration sensors, it is not necessary to expose at least the first electrode, which is the detection electrode, from the outer shell and immerse it in the liquid, and to seal the electrolyte from the liquid with the outer shell. In other words, hydrogen gas concentration can be detected with an extremely simple configuration.

[0035] In this embodiment, the hydrogen concentration of the hydrogen gas concentration sensor 10 is detected by the electromotive force generated between the first electrode piece 11 and the second electrode piece 12, and this electromotive force is generated based on the following relational expression.

[0036]

number

number

number

number

number

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0038] A hydrogen gas concentration sensor 10, as shown in Figure 1, was prepared, and a simple hydrogen gas detection test was conducted. The first electrode piece 11 used platinum and palladium wire with a diameter of 0.2 mm, and the second electrode piece 12 used tungsten wire with a diameter of 0.2 mm. For simplification, the third electrode piece 13 was omitted.

[0039] Next, the first electrode piece 11 and the second electrode piece 12 were placed in the electrolyte 14 made of cesium tungunstate with a gap of 0.2 mm between them. Furthermore, the first electrode piece 11, the second electrode piece 12, and the electrolyte 14 were housed and arranged in a glass tube 15 with a diameter of 6 mm and a length of 25 mm. The first electrode piece 11 was exposed for a length of 3 mm from the tip of the glass tube 15 and then fused and sealed. The exposed portion may be cut off at the base. There are no special restrictions on the arrangement of the electrolyte and electrodes.

[0040] Next, as shown in Figure 1, the first electrode piece 11 and the second electrode piece 12 are exposed from the rear end of the glass tube 15, allowing for measurement of the electromotive force obtained by detecting the hydrogen gas concentration. It is desirable to seal this measurement section to protect it from humidity and other factors.

[0041] Figure 2 shows the detection voltage (V) when a platinum wire is used as the first electrode piece 11, and Figure 3 shows the detection voltage (V) when a palladium wire is used as the first electrode piece 11.

[0042] The hydrogen gas concentration was adjusted by filling a sealed container, which had an opening into which the glass container 15 could be inserted, with hydrogen gas, and the detected electromotive force was measured at the rear end opening of the glass tube 15.

[0043] As shown in Figure 2, when a platinum wire is used as the first electrode piece 11, the detection voltage decreases from 0.4V to 0.03V upon detection of hydrogen gas. However, when contact with the hydrogen gas is cut off, the electromotive force immediately recovers to 0.4V. This indicates that the hydrogen gas departs quickly, making it suitable as a detection electrode for a hydrogen gas concentration sensor with a fast response. The measurement results were obtained at a temperature of 85°C, assuming a fuel cell control sensor.

[0044] In this example, the hydrogen concentration was set to 10% to compare the responsiveness to hydrogen gas. For measurements using a platinum wire as the first electrode piece 11, the spontaneous electromotive force of the sensor, a characteristic of EMF-type hydrogen sensors, was measured at the rear end opening of the glass tube 15 using an electrometer.

[0045] On the other hand, as shown in Figure 3, when a palladium wire is used as the first electrode piece 11, if hydrogen gas is detected at 1200 seconds, the detection voltage decreases from 0.15V to 0.1V, corresponding to the hydrogen concentration. Even if the hydrogen gas is removed at 3000 seconds, it takes more than 3000 seconds (50 minutes) to return to the original output value (0.15V). In other words, it has a memory function and is suitable for, for example, checking the deterioration of transformer oil. The measurement results were taken at a temperature of 20°C, assuming use at room temperature.

[0046] Next, using the same platinum wire as the first electrode piece 11, hydrogen gas was filled into a sealed container with an opening into which a glass container 15 could be inserted. The hydrogen concentration was then varied from 0 to 40 volume% at a temperature of 85°C, and the detection voltage was measured. The detection voltage was measured at the rear end opening of the glass tube 15. The measurement was performed using the electrometer described above.

[0047] As shown in Figure 4, when a platinum wire is used as the first electrode piece 11, the detection voltage decreases as the hydrogen gas concentration increases. In other words, the hydrogen gas concentration sensor 10 with the configuration shown in Figure 1 can detect the hydrogen gas concentration and function as a sensor. Therefore, the hydrogen gas concentration sensor 10 shown in Figure 1 can be applied to liquids such as oil to detect the concentration of hydrogen gas dissolved in these liquids.

[0048] Next, using the same palladium wire as the first electrode piece 11, hydrogen gas was filled into a sealed container with an opening into which a glass container 15 could be inserted. The hydrogen concentration was varied from 0 to 20 volume% at a temperature of 20°C, and the detection voltage was measured. The detection voltage was measured at the rear end opening of the glass tube 15. The measurement was performed using the electrometer described above.

[0049] As shown in Figure 5, when a palladium wire is used as the first electrode piece 11, the detection voltage increases as the hydrogen gas concentration increases while maintaining its memory function. In other words, the hydrogen gas concentration sensor 10 with the configuration shown in Figure 1 can detect the hydrogen gas concentration and function as a sensor. Therefore, the hydrogen gas concentration sensor 10 shown in Figure 1 can be applied to liquids such as oil to detect the concentration of hydrogen gas dissolved in these liquids.

[0050] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0051] 10. Hydrogen gas concentration sensor 11 First electrode piece 12 Second electrode piece 13 Third electrode piece 14 Electrolytes 15 Container

Claims

1. The device comprises a first electrode piece and a second electrode piece, an electrolyte in which these electrode pieces are arranged separately, and a container for housing the first electrode piece, the second electrode piece, and the electrolyte. The first electrode piece is H 2 (-)|50mol / m 3 H 2 SO 4 |Includes a first electrode material in which the standard electromotive force value of a cell composed of a material sample (+) is 0.8V or higher, The second electrode piece includes a second electrode material that exhibits a standard electromotive force value of less than 0.8V in the cell with the same configuration. A hydrogen gas concentration sensor characterized in that the first electrode piece penetrates the electrolyte and its end is exposed to the outside from the container.

2. The hydrogen gas concentration sensor according to claim 1, characterized in that the first electrode material comprises at least one of platinum, a platinum alloy, and a material containing these.

3. The hydrogen gas concentration sensor according to claim 1, characterized in that the first electrode material comprises at least one of palladium, a palladium alloy, and a material containing these.

4. The hydrogen gas concentration sensor according to claim 1, characterized in that the second electrode material comprises at least one of tungsten, tungsten alloy, nickel, nickel alloy, titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy, and materials containing these.

5. The hydrogen gas concentration sensor according to claim 1, characterized in that it comprises a third electrode piece for temperature compensation housed in the container and disposed in the electrolyte.

Images