JP2006300569A - Evaluation device of hydrogen storage material and evaluation method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaluation device of a hydrogen storage material capable of directly analyzing a hydrogen storage state qualitatively and quantitatively under the condition of the pressure, temperature or the like of an atmosphere where the hydrogen storage material and hydrogen are present, and an evaluation method of the hydrogen storage material. <P>SOLUTION: The evaluation device of the hydrogen storage material for evaluating the storage state of hydrogen stored in the hydrogen storage material is equipped with a high-pressure sample container 7 for housing the hydrogen storage material 4 and hydrogen, a light source 1 for irradiating the hydrogen storage material 4 in the container 7 with infrared rays and a detector 6 for detecting the infrared rays selectively absorbed by the hydrogen storage material 4. The high-pressure sample container 7 has an incident light window 2 comprising an infrared pervious body and allowing infrared rays to enter the container 7, an emitting light window 5 comprising the infrared pervious body and emitting the infrared rays, which are transmitted through or reflected by the hydrogen storage material 4, to the outside of the container 7 and a supply/discharge mechanism of hydrogen inside and outside of the container 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydrogen storage material evaluation apparatus and method for reversibly storing and releasing hydrogen. Specifically, the present invention relates to an apparatus and method for evaluating the bonding state between a hydrogen storage material and hydrogen in a high-pressure hydrogen atmosphere, and the amount of impurity gas in the stored hydrogen.

  Since hydrogen is one of the energy that does not pollute the global environment, it is expected that the amount used will increase in the future, and research is being conducted in a wide range of fields from hydrogen storage to application. In particular, various studies have been conducted on hydrogen storage materials expected to be used in fuel cell vehicles and the like, and evaluation of the amount of hydrogen storage.

  The conventional method for evaluating hydrogen storage is to measure the amount of stored hydrogen from changes in equilibrium hydrogen partial pressure or equilibrium temperature before and after hydrogen storage material is exposed to a hydrogen atmosphere and hydrogen is stored in this material. Is the method. This method is evaluated by a P (hydrogen pressure) -C (hydrogen storage amount) -T (temperature) characteristic curve, and is defined as a JIS standard shown in Non-Patent Document 1. In general, evaluation is performed using a PCT device (pressure-composition isotherm measuring device).

  FIG. 5 shows a schematic configuration diagram of the PCT apparatus. The apparatus includes a sample container 54 that stores the hydrogen storage material 4 and a thermostatic chamber 56 that covers the sample container 54. The sample container 54 is provided with a filter 53 so that the hydrogen storage material 4 as a sample does not scatter when the gas in the sample container 54 is taken in and out.

  The sample container 54 is connected to a pressure control mechanism. This pressure control mechanism includes an inert gas supply valve 50, a hydrogen supply valve 51, a sample container valve 52, a pressure gauge 57, a pressure storage container 58, a vacuum gauge 59, and a vacuum valve 60 that are connected to each other by piping.

  In order to use this PCT apparatus, an inert gas was previously introduced from an inert gas supply valve 50 and closed by an inert gas supply valve 50, a hydrogen supply valve 51, a vacuum valve 60, and a sample container valve 52. The volume of the portion including the inside of the piping and the pressure accumulating vessel 58 is obtained. Similarly, the volume of the part including the pipe on the sample container 54 side from the sample container valve 52 and the sample container is also obtained.

  When evaluating a hydrogen storage material with such an apparatus, first, the inert gas supply valve 50 and the hydrogen supply valve 51 are closed, the sample container valve 52 and the vacuum valve 60 are opened, and the vacuum gauge 59 is set to a predetermined value. The inside of the sample container 54 is sucked and degassed by an exhaust system until the pressure becomes. Next, the sample container valve 52 and the vacuum valve 60 are closed, the hydrogen supply valve 51 is opened, a predetermined amount of hydrogen is introduced, and the pressure in the pressure accumulating container 58 is measured by the pressure gauge 57. Next, the sample container valve 52 is opened, hydrogen is introduced into the sample container 54, hydrogen is stored in the hydrogen storage material 4, and the equilibrium pressure when the storage reaches equilibrium is measured by the pressure gauge 57. Thereafter, the same operation is repeated to gradually store hydrogen in the hydrogen storage material 4, and the amount of hydrogen stored in the hydrogen storage material 4 is obtained. When measuring the hydrogen release amount, conversely, the vacuum valve 60 is opened and the sample container valve 52 is closed to release hydrogen from the accumulator container system, and then the vacuum valve 60 is closed and the sample container valve 52 is opened. The pressure gauge 57 measures the equilibrium pressure when the pressure in the sample container 54 reaches equilibrium. Then, the amount of hydrogen released from the hydrogen storage material is measured to evaluate the hydrogen storage material.

In this method, the hydrogen storage amount or the hydrogen release amount is calculated based on the following Boyle-Charles law.
pv = nzRT
Where p: pressure, v: volume, n: number of moles of gas in volume v,
z: Gas compressibility, R: Gas constant, T: Temperature

  In this equation, z = 1 for an ideal gas. If this is applied to actual hydrogen as it is, an error of about 3% occurs in the measured hydrogen amount at a pressure of 5 MPa at room temperature. Correction is necessary to improve accuracy. In addition, in order to accurately measure the amount of hydrogen stored and released from the above equations, it is important to increase the measurement accuracy of repeatedly used volumes, pressures, and the like. The above needs to be taken into account in order to improve the measurement accuracy of the hydrogen storage amount by the PCT device.

  Non-Patent Document 2 discloses a technique using the PCT line (pressure-composition isotherm) and the absorption spectrum of infrared light in order to investigate the mechanism of hydrogen storage in the hydrogen storage material. ing. Here, the target hydrogen storage material is amorphous carbonitride.

JIS standard JIS H 7201 Jpn. J. Appl. Phys. Vol.42 (2003), pages 5251-5254, Part.1, No.8, August 2003

  However, the measurement method stipulated in Non-Patent Document 1 takes time to stabilize the storage of hydrogen in the hydrogen storage material, and the measurable pressure range is 1 KPa to 5 MPa, and in a high pressure state exceeding this range, The amount of hydrogen stored cannot be measured. If it is going to measure the amount of hydrogen stored in the hydrogen storage material in a high pressure state exceeding the above range, it may be possible to take the hydrogen storage material out of the PCT device and measure it by another method. In this case, the hydrogen storage amount cannot be measured with the PCT device in a high pressure state.

  Non-Patent Document 1 shows a technique for measuring the amount of hydrogen stored in the hydrogen storage material or the amount of hydrogen released from the hydrogen storage material, but the gas composition cannot be measured. Therefore, the technique of this document cannot elucidate the mechanism and state in which hydrogen is stored.

  Furthermore, when the atmospheric gas in the apparatus is a mixed gas containing an impurity gas other than hydrogen, the gas composition of the mixed gas cannot be measured. Even if trying to analyze the gas composition of the mixed gas with a gas chromatograph, etc., it is necessary to extract the mixed gas from the PCT device and introduce it into the analyzer. At that time, the pressure and temperature conditions of the mixed gas change, and the gas composition May change.

  On the other hand, Non-Patent Document 2 uses the absorption spectrum of infrared light to investigate the mechanism of hydrogen storage in hydrogen storage materials. However, this document does not disclose an apparatus or method for measuring an infrared absorption spectrum.

  The present invention has been made in view of the above circumstances, and one of its purposes is to store hydrogen in the hydrogen storage material under conditions such as the pressure and temperature of the atmosphere in which the hydrogen storage material and hydrogen exist. Another object of the present invention is to provide an apparatus and a method capable of directly and qualitatively or quantitatively analyzing the bonding state between the constituent atoms of the compound and the hydrogen storage material produced and the hydrogen atoms.

  Another object of the present invention is an apparatus that can directly analyze the atmosphere gas composition qualitatively or quantitatively with high accuracy under the conditions of the pressure, temperature, etc. of the atmosphere in which the hydrogen storage material and hydrogen exist. And to provide a way.

  When a hydrogen storage material exposed in hydrogen physicochemically binds to hydrogen, the bond selectively absorbs or scatters certain wavelengths of infrared light. Based on the knowledge that by measuring the amount of absorption and / or scattering of infrared light in the exposed atmosphere, the combined state of hydrogen and the hydrogen storage material and the amount of impurity gas in the atmosphere can be evaluated. Invented the invention. In this specification, evaluation means one or both of qualitative analysis and quantitative analysis of an object to be measured.

  The evaluation apparatus according to claim 1 is an evaluation apparatus for a hydrogen storage material that evaluates a storage state of hydrogen stored in the hydrogen storage material. This evaluation device detects a high-pressure sample container that contains hydrogen storage material and hydrogen, a light source that irradiates the hydrogen storage material in the container with infrared light, and infrared light that is selectively absorbed by the hydrogen storage material. Detector. The high-pressure sample container is made of an infrared transparent body, an incident light window for entering infrared light into the container, and infrared light made of an infrared transparent body that passes through or reflects the hydrogen storage material is emitted outside the container. And a mechanism for supplying and discharging hydrogen into and out of the container. This apparatus can evaluate the combined state of hydrogen and the hydrogen storage material as well as the measurement of the hydrogen storage / release amount without changing the exposure atmosphere of the hydrogen storage material. Here, detection means receiving infrared light and obtaining its absorption spectrum.

  In particular, this device qualitatively analyzes the bonding state formed by hydrogen stored and adsorbed in hydrogen storage materials in the range from atmospheric pressure to high pressure (about 100 MPa), and the hydrogen stored and adsorbed in hydrogen storage materials. The amount can be measured qualitatively or quantitatively.

  Here, occlusion refers to a state in which hydrogen storage material and hydrogen are chemically bonded, adsorption refers to a state in which hydrogen is physically attracted to the hydrogen storage material by intermolecular forces, etc., storage refers to occlusion and adsorption. It means the combined state. The hydrogen storage material to be evaluated may be anything as long as it has a hydrogen storage function, and may be either metallic or amorphous carbon.

  In this apparatus, the supply / discharge mechanism for hydrogen may be provided independently from the supply mechanism and the discharge mechanism, or a single mechanism may serve as both the supply mechanism and the discharge mechanism. As an example of the latter, both supply and discharge of hydrogen can be performed by opening and closing one hydrogen valve.

  The apparatus according to claim 2 is characterized by having a sample holder for holding the hydrogen storage material in the high-pressure sample container. By providing the sample holder, the hydrogen storage material can be held in a state suitable for transmission or reflection of infrared light. Here, holding means (1) sandwiching the hydrogen storage material between two infrared transparent bodies, (2) applying the hydrogen storage material to the surface of the holder made of the infrared transparent body, (3) placing the material Or the like can be used. Among these, when the hydrogen storage material is sandwiched between the sample holders, it is desirable to provide a large number of small holes in the sample holder so that the hydrogen and the hydrogen storage material are in good contact. In addition, the coating method has an advantage that since the contact area between hydrogen and the hydrogen storage material is large, the time until hydrogen storage and adsorption in the hydrogen storage material is stabilized is short. In the case of reflecting infrared light, a method of placing a hydrogen storage material is preferable.

  The sample holder according to claim 3 is made of an infrared transparent body. This is because if such an infrared transparent body is used for the sample holder, the hydrogen storage material can be measured with high accuracy by the transmission method.

  The apparatus according to claim 4 is an evaluation apparatus for measuring a composition of a mixed gas composed of hydrogen and impurity gas stored in the hydrogen storage material. This evaluation device detects a high-pressure sample container that contains hydrogen storage material and mixed gas, a light source that irradiates infrared light to the mixed gas stored in this container, and infrared light that is selectively absorbed by the mixed gas. Detector. The high-pressure sample container is made of an infrared transparent body, an incident light window for entering infrared light into the container, and infrared light made of an infrared transparent body and transmitted through the mixed gas is emitted outside the container. It has an emission light window and a mechanism for supplying and discharging hydrogen into and out of the container.

  This apparatus can qualitatively or quantitatively analyze the composition of the hydrogen storage material and the atmospheric gas in which hydrogen and the impurity gas coexist without changing the conditions such as pressure and temperature. Here, the impurity gas is a gas added to hydrogen, a gas generated when hydrogen is stored / released, a gas mixed from a pipe or the like, and a gas emitted from a cylinder. Specifically, it is a hydrocarbon such as methane or a compound of hydrogen and nitrogen.

  In this apparatus, similarly to the apparatus described in claim 1, the mixed gas supply mechanism and the discharge mechanism may be provided independently, or a single mechanism serves as both the supply mechanism and the discharge mechanism. Also good. Each of them is provided independently, and impurity-containing hydrogen from a cylinder whose gas composition changes with time can be passed through this evaluation apparatus to measure the amount of impurity gas in the hydrogen.

  The apparatus according to claim 5 includes a temperature measuring means and a pressure measuring means for the atmospheric gas in the high pressure sample container. By doing so, the evaluation apparatus of the present invention can be used as a PCT apparatus. This is because, since the amount of hydrogen stored in the hydrogen storage material can be measured quantitatively, for example, the relationship between the pressure in the high-pressure sample container and the amount of hydrogen stored in the hydrogen storage material can be grasped. Therefore, the measurement result of the PCT apparatus can be directly compared with the result of absorption of infrared light. However, when the function of the PCT apparatus is added to the evaluation apparatus, it is desirable that the evaluation apparatus has a pressure resistance up to 100 MPa, which is the same as the high-pressure sample container.

  The apparatus of the present invention further has an evaluation means for automatically calculating the hydrogen storage / release characteristics of the hydrogen storage material using the measurement results of the temperature measurement means and the pressure measurement means, the volume of the container and the state equation of the gas. Is preferred. Moreover, this evaluation apparatus can be provided in piping etc. which are hydrogen passages.

The device according to claim 6 is characterized in that, in each of the above-described devices, the infrared transparent body is any one of sapphire, diamond, SiC, ZnS, and ZnSe. An infrared transparent body is a material that transmits infrared light without absorbing it in a predetermined wavenumber region. The high-pressure sample container has an incident light window for introducing infrared light and an outgoing light window for extracting infrared light. These window materials are transparent to infrared light and desirably have a sufficiently large breaking strength compared to 10 MPa (≈1 kgf / mm ² ). For example, sapphire, diamond, SiC, ZnS, ZnSe, and the like correspond to this, and ZnSe is particularly preferable from the viewpoint of infrared translucency, moisture absorption resistance, and cost.

  The apparatus according to claim 7 is the above-described apparatus, wherein the high-pressure sample container is a cylindrical container with a lid and a bottom. The incident light window and the outgoing light window are provided on the peripheral surface of the cylindrical container. The cylindrical sample container is easy to obtain a high-strength material that can withstand a relatively high pressure, and the sample can be easily taken in and out. In addition, by providing an incident light window and an output light window on the peripheral surface of the cylindrical sample container, the lid of the end face of the cylindrical body can be opened and closed so that the sample can be easily put in and out of the container. In particular, it is desirable that the line connecting the incident light window and the outgoing light window pass through the center of the cylindrical sample container, that is, along the radial direction of the sample container. With this configuration, the incident light window and the output light window are opposed to each other, and the arrangement space for the hydrogen storage material is sufficiently secured in the center of the sample container, and the path of the incident light is not changed by reflection or the like. It can be led to the exit light window. It is desirable that the high-pressure sample container has a high strength so that measurement can be performed at a high pressure up to 100 MPa. In particular, when adding the above-described mechanism for analyzing infrared light to a conventional PCT apparatus to make the apparatus of the present invention also function as a PCT apparatus, the pressure resistance of piping members, valves, etc. other than the high-pressure sample container is improved. Increase.

  The device according to claim 8 is characterized in that, in each of the above-described devices, at least one of the incident light window and the outgoing light window is a disk or a cylinder having a diameter of 10 mm or less. By setting it as such a size, the sample container which can endure high pressure can be comprised easily. As for the shape of each window, a disk is preferable in terms of manufacturing and ease of assembling into a sample container, and the thickness may be increased when the operating pressure is increased to increase pressure resistance.

Next, the evaluation method of the present invention will be described.
The method for evaluating a hydrogen storage material according to claim 9 is a method for evaluating a storage state of hydrogen stored in the hydrogen storage material. First, a hydrogen storage material is placed in a high-pressure sample container, and the high-pressure sample container is sucked into a vacuum. Next, a predetermined amount of hydrogen is supplied to the high-pressure sample container, and when the temperature or pressure of the high-pressure sample container reaches equilibrium, infrared light is irradiated to the hydrogen storage material. Further, the present invention is characterized in that infrared light selectively absorbed by the hydrogen storage material is detected, and the storage state of the hydrogen stored in the hydrogen storage material is evaluated. According to this configuration, it is possible to evaluate the combined state of hydrogen and the hydrogen storage material as well as the measurement of the hydrogen storage / release amount of the hydrogen storage material in the state where the hydrogen storage material is exposed. Here, detection means receiving infrared light and obtaining its absorption spectrum.

  The method for evaluating a hydrogen storage material according to claim 10 is a method for evaluating a hydrogen storage material for evaluating a composition of a mixed gas composed of hydrogen and an impurity gas of the hydrogen storage material. First, a hydrogen storage material is placed in a high-pressure sample container, and the high-pressure sample container is sucked into a vacuum. Next, a predetermined amount of the mixed gas is supplied to the high-pressure sample container, and when the temperature or pressure of the high-pressure sample container reaches equilibrium, the mixed gas is irradiated with infrared light. Furthermore, the infrared light selectively absorbed by the mixed gas is detected, and the composition of the mixed gas is evaluated. According to this method, the composition of the hydrogen storage material and the atmospheric gas in which hydrogen and the impurity gas coexist can be qualitatively or quantitatively analyzed without changing the conditions such as pressure and temperature.

  By directly analyzing qualitatively or quantitatively the gas composition of the stored hydrogen and the atmosphere, it is possible to elucidate the mechanism such as adsorption and storage of hydrogen. Also, the function and effect of the catalyst gas can be confirmed.

  By using the apparatus and method of the present invention, the state of the hydrogen storage material can be evaluated in a wide temperature range from liquid nitrogen temperature to 500 ° C. in a wide pressure range from normal pressure to 100 MPa. A preferred temperature range is 0-100 ° C. In particular, the amount of hydrogen stored in the hydrogen storage material can be determined qualitatively and quantitatively. By these analyses, it is possible to directly analyze the compound produced by storing hydrogen in the hydrogen storage material and the bonding state between the constituent atoms of the hydrogen storage material and the hydrogen atoms. Moreover, since the hydrogen storage material is not moved to another apparatus in the evaluation, the time required for the evaluation is short.

  Further, qualitative and quantitative analysis of the mixed gas could not be performed by the conventional PCT apparatus, but has become possible by using the apparatus and method of the present invention. In particular, it has become possible to directly evaluate the impurity gas composition in hydrogen under high pressure without changing the temperature and pressure. Therefore, accurate measurement can be performed in a short time.

  Therefore, it is possible to eliminate the error factors that have been a problem in the conventional PCT apparatus, more specifically, the error factors of pressure, metering volume, and temperature that affect the calculation of the hydrogen storage amount.

  FIG. 1 is a schematic configuration diagram of a high-pressure sample container used in the apparatus of the present invention. The high-pressure sample container 7 is a cylindrical container composed of a lid 8 and a container part 9. In this example, the hydrogen storage characteristics can be measured at a high internal pressure of up to about 100 MPa. For this purpose, the lid 8 and the container 9 are firmly tightened with bolts (not shown).

  Further, an incident light window 2 and an outgoing light window 5 are provided at positions opposed to the peripheral surface of the container 7, and a sample holder 3 is provided at an intermediate position between the two windows 2 and 5, that is, at the center of the container 7. ing. In FIG. 1, since the transmission method is used for evaluation, a pair of plates made of an infrared transparent body is used as a sample holder 3, and a hydrogen storage material 4 is sandwiched between the holders 3. Each plate constituting the sample holder has a large number of small through holes 14 so that hydrogen and the hydrogen storage material are in good contact with each other.

  On the other hand, on the outside of the container 7, a light source 1 that irradiates infrared light 13 is disposed facing the incident light window 2, and a detector 6 is disposed facing the outgoing light window 5. The detector 6 detects the infrared light 13 that is selectively absorbed by the hydrogen storage material held in the sample holder 4. Here, detection means receiving infrared light and obtaining its absorption spectrum.

  Further, a pipe for introducing hydrogen into the container and a pipe for discharging hydrogen are connected to the container 7, and a hydrogen introduction valve 10 and a hydrogen release valve 11 are provided in these pipes. The container 7 is connected to an exhaust system so that the inside of the container 7 can be adjusted to a vacuum. Although not shown, the high-pressure sample container is installed in the evaluation apparatus of the present invention. The evaluation apparatus further includes a pressure gauge for measuring the pressure in the container, a thermometer for measuring the temperature in the container, and heating / cooling of the atmospheric gas. A device is provided.

  When evaluating the hydrogen storage material which stored hydrogen using such an apparatus, it evaluates with the following procedure. First, after the high-pressure sample container 7 is sufficiently evacuated, the gas release valve 11 is closed and the hydrogen introduction valve 10 is opened, and then hydrogen is introduced into the container 7. The introduced hydrogen is occluded and adsorbed by the hydrogen storage material 4, and the pressure in the high-pressure sample container 7 gradually decreases. A pressure gauge (not shown) is used to measure the pressure when the pressure in the container is in equilibrium. Next, infrared light is generated from the light source 1, and the infrared light passes through the incident light window 2 through the hydrogen storage material held by the sample holder 3, and passes through the outgoing light window 5 to the detector 6. It reaches. The absorption spectrum analysis of the infrared light absorbed by the detector 6 is performed to determine the amount of hydrogen stored in the hydrogen storage material.

  FIG. 3 is a schematic view of another high-pressure sample container used in the present invention. The reference numerals are the same as in FIG. The high-pressure sample container 7 allows infrared light to pass through a high-pressure hydrogen atmosphere gas to evaluate the gas composition and the like, and simultaneously obtain the amount of hydrogen stored in the hydrogen storage material 4 by a reflection method. In the figure, 1a, 6a and 13a are a light source, a detector and infrared light for obtaining hydrogen in the hydrogen storage material by a reflection method.

  Thus, according to the apparatus of the present invention, the amount of hydrogen stored in the hydrogen storage material 4, the type of gas in the atmospheric gas, and the composition thereof can be obtained from the infrared absorption spectrum.

  The intensity of the infrared light to irradiate only needs to provide a difference (sensitivity) necessary for the measurement accuracy of the hydrogen storage amount by the spectral change of the infrared light due to the combination of hydrogen and hydrogen atoms in the hydrogen storage material. . Moreover, the wave number of the infrared light to irradiate should just be a wave number including the wave number corresponding to the characteristic wave number of the stretching vibration and bending vibration when a hydrogen storage material and hydrogen couple | bond. Therefore, a wavelength range of 300 Kaiser to 4000 Kaiser is appropriate as a wavelength band used for infrared light. This is because when the hydrogen storage material stores hydrogen, the main absorption of infrared light by the hydrogen storage material and the atmospheric gas falls within this range.

  For example, when a hydrogen storage material combines with hydrogen and absorbs infrared light, absorption is hardly observed below 300 Kaiser. On the other hand, in some cases, infrared absorption at 4000 Kaiser or higher is observed, but in most cases, hydrogen bonds resulting from the absorption are also observed as absorption in the infrared region corresponding to wave numbers of 4000 Kaiser or lower. Therefore, it is possible to save the trouble of observing by switching the measurement wavenumber region to the range of 4000 Kaiser or more (usually switching to another range for 4000 Kaiser or more), and the measurement work becomes more efficient.

  This example is an experiment for determining the amount of hydrogen stored in a hydrogen storage material by transmitting infrared light. First, a hydrogen storage material was produced as follows. A mixed gas of methane and nitrogen was introduced into a 200 W microwave plasma CVD apparatus to produce an amorphous carbon-based hydrogen storage material. The hydrogen storage material was sandwiched between ZnSe sample holders and mounted in a high-pressure sample container shown in FIG. The high-pressure sample container was composed of a stainless steel cylindrical container and a lid, and the lid was firmly attached to the container with bolts. As for the window material, an incident light window and an output light window having a ZnSe diameter of 10 mm and a thickness of 10 mm are formed on the side surface of the cylindrical container so as to face each other.

  In order to evaluate the hydrogen storage / release characteristics with the PCT apparatus, in addition to the hydrogen storage material sandwiched between the ZnSe described above, 1 g of a powdered hydrogen storage material was also inserted into the high-pressure sample container. This is because the amount of hydrogen storage material on ZnSe alone is small and the PCT device cannot evaluate the hydrogen storage state. In this way, the bolt of the high-pressure sample container was firmly tightened.

  The high-pressure sample container 7 shown in FIG. 1 was mounted on the PCT apparatus as the sample container 54 of the PCT apparatus shown in FIG. 5, the temperature was set to 300 K, and the system was evacuated. Next, the absorption state of infrared light in the initial state of the hydrogen storage material was examined. Infrared light is irradiated from the light source in FIG. 1 onto the hydrogen storage material held in the sample holder, and the transmitted light is received by the detector 6 through the outgoing light window, and the infrared light absorption shown in 20 of FIG. A spectrum was obtained.

  Hydrogen was added in small portions, and the amount of hydrogen stored in an equilibrium state was measured by a PCT apparatus and absorption of infrared light. The amount of hydrogen stored reached its maximum at 12 MPa, and hydrogen was released from the system below. The amount of hydrogen released was determined from the amount of absorption of PCT rays and infrared light in the same manner as the amount stored. A typical example of the absorption state of infrared light when the pressure in the high-pressure sample container is atmospheric pressure (0.1 MPa) is shown in FIG.

In FIG. 2, the vertical axis represents the amount of absorbed infrared light, and the horizontal axis represents the wave number. However, although the background level overlaps before and after hydrogen storage, it is moved in parallel in the vertical direction to make the spectrum easier to see. The peak 22 in FIG. 2 is an absorption position based on the stretching vibration of CH ₃ , and the peak 23 is an absorption position based on the stretching vibration of CH ₂ . The peak 24 is an absorption position based on the CH ₃ bending vibration, and the peak 25 is an absorption position based on the CH ₂ bending vibration. Infrared light absorption spectra before and after hydrogen storage are shown in 20 and 21, respectively.

Looking at the amount of absorption due to stretching vibration and bending vibration before and after hydrogen storage, it can be seen that the amount of absorption after hydrogen storage is large. Hydrogen stored in the hydrogen storage material, has been shown to form a CH ₃ or CH _2. Since the hydrogen storage material used in this example is amorphous carbon, it is considered that hydrogen is bonded to the dangling bonds. In addition, hydrogen stored once is still stored in the form of CH ₃ and CH ₂ even at 0.1 MPa.

Furthermore, the relationship between the hydrogen storage amount obtained by the PCT apparatus and the infrared absorption amount obtained by the infrared absorption spectrum was investigated. In the infrared absorption spectrum shown in FIG. 2, it was found that there was a correlation between the highly sensitive CH ₃ stretch 22 and the amount of hydrogen stored, and this was taken as a calibration curve. By using this calibration curve, the amount of hydrogen stored in the hydrogen storage material can be measured quantitatively, and the amount of hydrogen stored can be measured quantitatively in a short time with a simple operation. It was found that there was a correlation between the hydrogen storage amount and the infrared absorption spectrum even when the atmospheric pressure fluctuated.

  In this example, the composition of the mixed gas of hydrogen and impurities was evaluated. The following experiment was performed using the same evaluation apparatus and the same hydrogen storage material as in Example 1. However, the high pressure sample container shown in FIG. 3 was used to evaluate the composition of hydrogen gas and the amount of hydrogen stored in the hydrogen storage material. First, a predetermined amount of the hydrogen storage material 4 was placed on the sample holder 3, and 1 g of hydrogen storage material (not shown) was placed in the high-pressure sample container. After increasing the pressure to 12 MPa using hydrogen in the same manner as in Example 1, the gas was released from the container and released to 0.1 MPa.

  Meanwhile, the composition of the gas was measured as appropriate to grasp the variation of the gas composition. Further, the amount of hydrogen stored in the hydrogen storage material was measured by receiving reflected light of infrared light. In the process of increasing the pressure of hydrogen, the compositional variation of hydrogen could not be grasped, but it was confirmed that impurity gases other than hydrogen were included in the process of depressurization. The impurity gas contained methane gas. It is considered that the above impurity gas was generated by the reaction between the hydrogen storage material and hydrogen.

  Further, it was found that there is a correlation between the amount of hydrogen stored in the hydrogen storage material and the infrared absorption spectrum as in Example 1. It was also confirmed that the amount of hydrogen stored can be quantitatively evaluated by the reflection method.

In the above experiments, it has become important to quantitatively determine methane in hydrogen. Therefore, we investigated whether methane can be obtained quantitatively even under high pressure. Standard gases with methane contents of 1.29 x 10 ^-2 mol%, 3.23 x 10 ^-2 mol%, and 6.45 x 10 ^-2 mol% are prepared and filled in a high-pressure sample container at a pressure of 5 MPa. did.

  The mixed gas was irradiated with infrared light from a light source, and the absorption characteristics of infrared light were examined. As shown in FIG. 4, it was found that the CH stretching vibration, the infrared absorption amount of the CH bending vibration, and the amount of methane introduced were in a proportional relationship, and quantitative analysis was possible. The unit a.u. on the vertical axis means an arbitrary unit.

  Of the methods of reflecting infrared light by the hydrogen storage material, there is a method different from that shown in FIG. In this method, the hydrogen storage material is irradiated with infrared light substantially perpendicularly, reflected substantially perpendicularly, the reflected light is extracted from the incident light window, and the outgoing light window is omitted. In this case, interference between the light source and the detector can be prevented as follows. When infrared light is incident on the hydrogen storage material at a slight angle from the vertical, the reflected light does not overlap the incident light, so that interference between the light source and the detector can be prevented. Another means is a method of irradiating the hydrogen storage material with infrared light perpendicularly. In this case, the reflected light is emitted from the incident window in the opposite direction to the incident light. By emitting the emitted light at a different angle by a half mirror provided between the light source and the incident light window, for example, overlapping with the incident light can be eliminated and interference between the light source and the detector can be prevented.

  The present invention can be used as a sensor for grasping the operating status of a hydrogen battery, in addition to the development and research fields of hydrogen storage materials and fuel cells. In addition, by providing this evaluation device in a hydrogen supply pipe or the like, it is possible to automatically measure flowing hydrogen and use it for quality control.

It is a general | schematic cross-section block diagram of the high-pressure sample container used for this invention apparatus. It is an infrared-light absorption spectrum of the hydrogen storage material measured by the method of the present invention. It is a general | schematic cross-section block diagram of another high-pressure sample container used for this invention apparatus. The calibration curve of impurity gas with respect to hydrogen obtained when evaluating the amount of impurity gas of the hydrogen storage material by the method of the present invention is shown. It is a schematic block diagram of a PCT apparatus.

Explanation of symbols

1 Light source 2 Incident light window
3 Sample holder 4 Hydrogen storage material
5 Outgoing light window 6 Detector
7 High-pressure sample container 8 Lid
9 Container 10 Hydrogen introduction valve
11 Hydrogen release valve
13 Infrared light 14 Through hole
20 Before hydrogen storage 21 After hydrogen storage
22 CH ₃ telescopic 23 CH ₂ telescopic
24 CH ₃ variable angle 25 CH ₂ variable angle
30 CH expansion / contraction 31 CH deflection
50 Inert gas supply valve 51 Hydrogen supply valve
52 Sample container valve 53 Filter
54 Sample container 55 Thermometer
56 Thermostatic chamber 57 Pressure gauge
58 Accumulation vessel 59 Vacuum gauge
60 Vacuum valve

Claims (10)

A hydrogen storage material evaluation device for evaluating a storage state of hydrogen stored in a hydrogen storage material,
A high-pressure sample container for storing a hydrogen storage material and hydrogen;
A light source for irradiating the hydrogen storage material in the container with infrared light;
A detector for detecting infrared light selectively absorbed by the hydrogen storage material,
The high-pressure sample container is
An incident light window made of an infrared transparent body and receiving infrared light into the container;
An emission light window through which infrared light made of an infrared transparent body and transmitted or reflected by the hydrogen storage material is emitted outside the container;
An apparatus for evaluating a hydrogen storage material, comprising a mechanism for supplying and discharging hydrogen into and out of the container.   2. The apparatus for evaluating a hydrogen storage material according to claim 1, further comprising a sample holder for holding the hydrogen storage material in the high-pressure sample container.   3. The apparatus for evaluating a hydrogen storage material according to claim 2, wherein the sample holder is made of an infrared transparent body. An apparatus for evaluating a hydrogen storage material that measures the composition of a mixed gas composed of hydrogen and an impurity gas stored in the hydrogen storage material,
A high-pressure sample container containing a hydrogen storage material and a mixed gas;
A light source for irradiating the mixed gas stored in the container with infrared light;
A detector for detecting infrared light selectively absorbed by the mixed gas,
The high-pressure sample container is
An incident light window made of an infrared transparent body and receiving infrared light into the container;
An outgoing light window from which infrared light made of an infrared transparent body and transmitted through the mixed gas is emitted to the outside of the container;
An apparatus for evaluating a hydrogen storage material, comprising a mechanism for supplying and discharging hydrogen into and out of the container.   5. The apparatus for evaluating a hydrogen storage material according to claim 1, wherein the evaluation apparatus includes a temperature measurement unit for atmospheric gas in the high-pressure sample container and a pressure measurement unit.   6. The apparatus for evaluating a hydrogen storage material according to claim 1, wherein the infrared transparent body is sapphire, diamond, SiC, ZnS, or ZnSe. The high-pressure sample container consists of a cylindrical container with a lid and a bottom,
7. The hydrogen storage material evaluation apparatus according to claim 1, wherein the incident light window and the outgoing light window are provided on a peripheral surface of the cylindrical container.   8. The hydrogen storage material evaluation apparatus according to claim 1, wherein at least one of the incident light window and the output light window is a disk or a cylinder having a diameter of 10 mm or less. A hydrogen storage material evaluation method for evaluating a storage state of hydrogen stored in a hydrogen storage material,
Place hydrogen storage material in the high-pressure sample container,
Aspirating the high pressure sample container to a vacuum;
A predetermined amount of hydrogen is supplied to the high-pressure sample container,
When the temperature or pressure in the high-pressure sample container reaches equilibrium, the hydrogen storage material is irradiated with infrared light,
Detecting infrared light selectively absorbed by the hydrogen storage material,
A method for evaluating a hydrogen storage material, wherein the storage state of hydrogen stored in the hydrogen storage material is evaluated based on the detection result. A hydrogen storage material evaluation method for evaluating the composition of a mixed gas comprising hydrogen and impurity gas of a hydrogen storage material,
Place hydrogen storage material in the high-pressure sample container,
Aspirating the high pressure sample container to a vacuum;
A predetermined amount of the mixed gas is supplied to the high-pressure sample container,
When the temperature or pressure of the high-pressure sample container reaches equilibrium, the mixed gas is irradiated with infrared light,
Infrared light selectively absorbed by the mixed gas is detected,
A method for evaluating a hydrogen storage material, wherein the composition of a mixed gas is evaluated from the detection result.

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