JP2007051990A - Measuring device and measuring method for measuring permeation characteristic of membrane by using nuclear magnetic resonance method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring device and a measuring method having high reliability, capable of calculating a permeation characteristic of a protonic solvent of a membrane. <P>SOLUTION: The measuring device 1 has a static magnetic field application part (magnet 113) for applying a static magnetic field to a solid polymer electrolyte film 115; a small-sized RF coil 114 smaller than the solid polymer electrolyte film 115, for applying an oscillating magnetic field for excitation to the solid polymer electrolyte film 115, and acquires an NMR signal corresponding to the oscillating magnetic field for excitation; and a permeation characteristic operation part 132 for acquiring a spectrum of a chemical shift value showing only methanol based on a nuclear magnetic resonance signal acquired by the small-sized RF coil 114, and calculating the permeability of methanol on a specific spot in the solid polymer electrolyte film 115, based on the spectrum intensity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for measuring transmission characteristics of at least one protic solvent at a specific location in a film containing two or more types of protic solvents using a nuclear magnetic resonance method.

In order to grasp the characteristics of a certain type of functional film, it is important to grasp the behavior of solvent molecules in the functional film.
For example, when two or more kinds of solvent molecules are included in the functional film, the movement of at least one solvent molecule may dominate the performance of the functional film.
An example of such a functional membrane is a solid polymer electrolyte membrane used in a direct methanol fuel cell.

In a direct methanol fuel cell, a mixed liquid of water and methanol having a predetermined concentration is supplied to the fuel electrode side, and air (oxygen) is supplied to the air electrode side. The fuel electrode and the air electrode are partitioned by a solid polymer electrolyte membrane to prevent direct reaction between methanol and air (oxygen).
In order to increase the power generation efficiency of such a direct methanol type fuel cell, it is necessary that the solid polymer electrolyte membrane contains a sufficient amount of water to improve the wettability of the solid polymer electrolyte membrane.
On the other hand, it is necessary to reduce the “crossover” by reducing the amount of methanol in the solid polymer electrolyte membrane. “Crossover” refers to a phenomenon in which methanol enters a solid polymer electrolyte membrane containing a large amount of water and reaches the air electrode. When crossover occurs, methanol is oxidized regardless of power generation, not only wastefully consuming methanol, but also reducing the cell voltage.

In view of this, a method has been proposed in which the power generation current in the entire cell of the fuel cell is measured during power generation to grasp the crossover characteristics of methanol in the solid polymer electrolyte membrane.
There is also a method for measuring the methanol crossover characteristics of solid polymer electrolyte membranes by measuring methanol leaking from the air electrode side and carbon dioxide generated on the air electrode side with a chemical analyzer (gas chromatography, etc.). Yes (see Patent Document 1).

Japanese Patent Laid-Open No. 2005-026215

However, the conventional measurement method described above has room for improvement as follows.
A catalyst is applied to the fuel electrode side of the fuel cell. In the vicinity of the catalyst, a concentration distribution of methanol is created, and there is a difference in concentration between the concentration of methanol in the vicinity of the catalyst and the concentration of methanol in other portions. Arise.
Depending on the difference in concentration, the diffusion coefficient of methanol in the catalyst layer, and the mass transfer rate on the aqueous solution side, the mass flux at which methanol is supplied to the catalyst surface is determined. Will be affected.
The generated current is also greatly influenced by the particle diameter of the applied catalyst, the pore diameter of the catalyst, the density of the catalyst, and the catalyst performance.
Furthermore, a catalyst is also applied to the air electrode side of the fuel cell, and an oxygen concentration distribution is created in the vicinity of the catalyst, and the concentration is between the oxygen concentration in the vicinity of the catalyst and the oxygen concentration in other parts. There is a difference.
Depending on this concentration difference, the diffusion coefficient of oxygen in the catalyst layer, and the mass transfer rate on the air side, the mass flux at which oxygen is supplied to the catalyst surface is determined. It will have a big impact.
Therefore, since the generated current of the entire fuel cell as described above is affected by a large number of factors, even if the generated current is measured, it is not possible to specify that the cause of the current decrease is the methanol crossover. difficult.
Therefore, it is difficult to obtain a methanol crossover characteristic and a methanol permeation characteristic of a highly reliable solid polymer electrolyte membrane.

On the other hand, the method for measuring methanol leaking from the air electrode side also has the following problems.
The methanol that has passed through the solid polymer electrolyte membrane is burned by the catalyst on the air electrode side, but the unburned methanol remains on the catalyst surface. Since the methanol concentration on the catalyst surface is high and the methanol concentration on the air side of the air electrode is low, methanol on the catalyst surface leaks from the air electrode side due to diffusion and convection based on the difference in methanol concentration.
Therefore, the concentration of methanol measured on the air electrode side is a coefficient related to the diffusion and movement of methanol such as catalyst particle diameter, catalyst pore diameter, and catalyst coating density (methanol diffusion coefficient in the catalyst layer), It depends greatly on the coefficient (substance transfer rate) related to substance transfer, such as the air flow speed on the air electrode side and the air flow path width.
In this way, even in the method of measuring methanol leaking from the air electrode side, the methanol concentration is affected by a large number of factors, so the methanol crossover characteristics of a highly reliable solid polymer electrolyte membrane Furthermore, it is difficult to obtain the permeation characteristics of methanol.
Furthermore, in the method of measuring carbon dioxide generated on the air electrode side, carbon dioxide generated along with the combustion of methanol by the catalyst on the air electrode side is measured. The amount of carbon dioxide generated varies depending on particle diameter, catalyst pore diameter, catalyst coating density, diffusion coefficient of methanol or oxygen in the catalyst layer, mass transfer rate of methanol or oxygen to the catalyst, and the like. Therefore, it is difficult to obtain a methanol crossover characteristic and a methanol permeation characteristic of a highly reliable solid polymer electrolyte membrane.

  An object of the present invention is to provide a measurement apparatus and a measurement method that can calculate the permeation characteristics of a protic solvent of a membrane with high reliability.

According to the present invention, there is provided a measuring apparatus for measuring the permeation characteristics of at least one protic solvent at a specific location in a membrane containing two or more kinds of protic solvents,
A static magnetic field application unit that applies a static magnetic field to the film;
A small RF coil smaller than the film, which applies an oscillating magnetic field for excitation to the film and acquires a nuclear magnetic resonance signal generated at a specific location in the film;
Based on the nuclear magnetic resonance signal acquired by the small RF coil, a spectrum of a chemical shift value indicating only the one protic solvent is acquired, and based on the intensity of the spectrum, the specific location in the film A ratio of the amount of one protic solvent, and a permeation characteristic calculator that calculates at least one of the amount of the one protic solvent at a specific location in the membrane;
An output unit that outputs the value calculated by the transmission characteristic calculation unit as the transmission characteristic;
There is provided a measuring device characterized by comprising:

  In the present invention, an oscillating magnetic field for excitation is applied to a specific location in the film, a nuclear magnetic resonance signal generated in the film is acquired, and the ratio or amount of the protic solvent amount is measured. I know the transmission characteristics. Therefore, when measuring the permeation characteristics of the protic solvent through the membrane as in the prior art, the catalyst particle size, catalyst pore size, catalyst coating density, diffusion coefficient of methanol or oxygen in the catalyst layer, methanol or oxygen catalyst Many factors, such as mass transfer rate, are not affected. Therefore, in the measuring apparatus of the present invention, it is possible to obtain a highly reliable protic solvent permeation characteristic.

  Furthermore, in the present invention, the ratio or amount of the protic solvent at a specific location of the membrane is measured based on the chemical shift value spectrum indicating only the protic solvent to be measured. Based on the chemical shift value, it is possible to distinguish a spectrum showing only the protic solvent to be measured from a spectrum caused by other protic solvents, so that two or more kinds of protic solvents are present in the film. Even in some cases, the ratio and amount of the protic solvent to be measured can be measured separately from other protic solvents.

Here, when measuring the permeation characteristics of the protic solvent at a specific location of the membrane based on the spectrum of the chemical shift value indicating only the protic solvent to be measured, an RF larger than the membrane is covered. It is also conceivable to use a coil.
To obtain a chemical shift value spectrum indicating only the protic solvent to be measured, the uniformity of the static magnetic field in the measurement region of the RF coil must be very high, but a large RF coil is used. This increases the measurement area of the RF coil. That is, the area where the static magnetic field must be uniform becomes wide. Therefore, there are significant restrictions on the method of generating a static magnetic field in the static magnetic field application unit and the selection of the shape of the magnet used in the static magnetic field application unit.
On the other hand, in the present invention, since a small RF coil smaller than the film is used, the measurement area is small, and the area where the static magnetic field must be made uniform can be narrowed. Thereby, the choices, such as the generation method of the static magnetic field in a static magnetic field application part, and the shape of the magnet used for a static magnetic field application part, can be expanded.

Also, the performance of two different types of solid polymer electrolyte membranes using the conventional method of measuring the generated current of the entire cell of the fuel cell and the method of measuring methanol and carbon dioxide leaking from the air electrode side ( When trying to evaluate methanol crossover characteristics and methanol (protic solvent) permeation characteristics, when measuring two different types of solid polymer electrolyte membranes, the diffusion coefficient of methanol and oxygen in the catalyst layer, methanol And so many factors, including the mass transfer rate of oxygen to the catalyst, etc. must be exactly the same.
Therefore, it has been very difficult to evaluate the permeation characteristics of protic solvents of different membranes, and further the membrane performance, using conventional measurement methods.
On the other hand, as described above, the permeation characteristics of the protic solvent obtained in the present invention are not affected by many factors as in the prior art, so that the permeation characteristics of the protic solvent of the membrane and the performance of the membrane are easy. And it can evaluate accurately.

Here, as an example of evaluating the performance of the membrane, a case where the membrane is a solid polymer electrolyte membrane for a fuel cell will be described.
A solid polymer electrolyte membrane for a fuel cell generally contains alcohol (methanol) and water as a protic solvent.
When the ratio of the amount of methanol at a specific location of the solid polymer electrolyte membrane is high (or the amount of methanol is large), it is generally considered that the membrane is prone to crossover when incorporated in a fuel cell. Therefore, it can be estimated that the performance (crossover characteristics) of the solid polymer electrolyte membrane is not good.
Further, when the ratio of the amount of methanol at a specific portion of the solid polymer electrolyte membrane is low (or the amount of methanol is small), it is generally considered that the membrane is less likely to cause crossover when incorporated in a fuel cell. Therefore, it can be estimated that the crossover property of the solid polymer electrolyte membrane is good.

Moreover, in this specification, a protic solvent means the solvent which dissociates itself and produces a proton. Examples of protic solvents include water;
Alcohols such as methanol and ethanol;
Carboxylic acids such as acetic acid;
Phenol;
Liquid ammonia;
Is mentioned.
Furthermore, the static magnetic field in the present invention may not be a completely stable magnetic field as long as it is a temporally stable magnetic field capable of stably acquiring a nuclear magnetic resonance signal. There may be some variation.
Further, the ratio of the amount of one protic solvent at a specific location in the membrane may be the ratio of the amount of one protic solvent to the amount of all protic solvents contained in the specific location of the membrane, It may be a ratio of one protic solvent amount to a certain protic solvent amount.

In the present invention,
The transmission characteristic calculator is
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum caused by each protic solvent contained in the membrane, and the amount of the one protic solvent relative to the total amount of the protic solvent Correlation with the ratio of
and,
A storage unit storing at least one of the correlation between the intensity of the spectrum indicating only the one protic solvent and the amount of the one protic solvent;
Based on the nuclear magnetic resonance signal acquired by the small RF coil, a spectrum resulting from each protic solvent at the specific location including a spectrum of a chemical shift value indicating only the one protic solvent is acquired,
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum due to each protic solvent at a specific location in the membrane,
and,
Calculating at least one of the intensities of the spectrum of the chemical shift value indicating only the one protic solvent,
Based on the correlation stored in the storage unit, the ratio of the one protic solvent amount to the total protic solvent amount at a specific location in the membrane, and the protic solvent at a specific location in the membrane A calculation unit for calculating at least one of the quantities;
It is preferable to have.

Furthermore, in the present invention,
The membrane contains water and alcohol as the protic solvent,
In the storage unit, there is a correlation between the ratio of the spectrum intensity indicating only the alcohol to the total value of the spectrum intensity caused by water and alcohol, and the ratio of the alcohol amount to the total amount of water and alcohol. Remembered,
The calculation unit of the transmission characteristic calculation unit calculates the ratio of the alcohol amount to the total amount of water and alcohol at a specific location in the membrane, and the water content with respect to the total amount of water and alcohol at the specific location in the membrane. It is preferable to calculate the ratio.
According to such a configuration, the ratio of two types of protic solvents (water and alcohol) contained in the membrane can be calculated. Thereby, the permeation | transmission characteristic of each protic solvent in the specific location of a film | membrane can each be grasped | ascertained, and the performance of a film | membrane can be grasped | ascertained more correctly.
For example, when the membrane is a solid polymer electrolyte membrane used in a fuel cell, it is necessary to increase the amount of water in the solid polymer electrolyte membrane, while reducing the amount of alcohol in the solid polymer electrolyte membrane. It is necessary to let By grasping the ratio of the amount of water contained in the membrane and the ratio of the amount of alcohol, the performance of the solid polymer electrolyte membrane can be grasped more accurately, and the evaluation of the solid polymer electrolyte membrane can be performed more accurately. It can be carried out.
In addition, the occurrence of crossover can be more reliably reduced by more accurately grasping the performance of the solid polymer electrolyte membrane.

Furthermore, in the present invention,
A plurality of the small RF coils;
The plurality of small RF coils apply an oscillating magnetic field for excitation to a plurality of specific portions of the film,
Obtaining a nuclear magnetic resonance signal corresponding to the oscillating magnetic field for excitation,
It is preferable that the permeation characteristic calculation unit calculates at least one of the ratio of the one protic solvent amount and the one protic solvent amount at a plurality of specific locations of the membrane.

  According to such a configuration, it is possible to simultaneously measure the transmission characteristics at a plurality of specific locations in the film. Thereby, the distribution of the transmission characteristics of the membrane can be obtained.

Furthermore, in the present invention,
A gradient magnetic field application unit for applying a gradient magnetic field to the film;
A first measurement mode for measuring the permeation characteristics of at least the one protic solvent at a specific location in the membrane; and a first measurement mode for measuring the mobility of at least the one protic solvent at a specific location in the membrane. A measurement mode selector for selecting one of a plurality of measurement modes including two measurement modes;
A control unit that controls operations of the small RF coil and the gradient magnetic field application unit according to the measurement mode selected by the measurement mode selection unit;
A mobility calculator that calculates the mobility of the protic solvent at a specific location in the film based on the nuclear magnetic resonance signal acquired in the second measurement mode;
The controller is
When in the first measurement mode, an excitation oscillating magnetic field is applied to the specific part of the film by the small RF coil, and nuclear magnetic resonance is generated at the specific part corresponding to the excitation oscillating magnetic field. A signal is acquired by the small RF coil;
When in the second measurement mode, an oscillating magnetic field for excitation is applied to a specific portion of the film by the small RF coil, and a gradient magnetic field is applied by the gradient magnetic field application unit. It is preferable that the generated nuclear magnetic resonance signal is acquired by the small RF coil.

In the first measurement mode, by using a small RF coil that is smaller than the membrane, the region to be measured is limited, and the permeation characteristics of the protic solvent at a specific location can be measured. Also in the second measurement mode, the gradient magnetic field application unit and the small RF coil can be used to limit the part to be measured and to measure the mobility at a specific part.
Therefore, since the permeation characteristics of the protic solvent and the mobility of the protic solvent can be measured at the same position of the membrane, the local behavior of the protic solvent in the membrane can be accurately grasped.
Here, “mobility” measured by the present invention refers to a physical property value indicating the ease of movement of a protic solvent in a sample. Such physical property values include parameters such as self-diffusion coefficient and mobility (movement speed).

Further, according to the present invention, there is provided a measuring method for measuring the permeation characteristics of at least one protic solvent at a specific location in a membrane containing two or more kinds of protic solvents,
An excitation oscillating magnetic field is applied to a specific part of the film placed in a static magnetic field using a small RF coil smaller than the film, and a nuclear magnetic resonance signal generated at the specific part in the film is acquired. Process,
Based on the nuclear magnetic resonance signal acquired by the small RF coil, including a spectrum of a chemical shift value indicating only the one protic solvent, obtain a spectrum caused by each protic solvent in the specific location,
The ratio of the intensity of the spectrum of the chemical shift value indicating only the one protic solvent to the total value of the intensity of the spectrum caused by each protic solvent at a specific location in the membrane,
and,
Calculating at least one of the intensity of the spectrum of the chemical shift value indicating only the one protic solvent;
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum due to each protic solvent contained in the membrane, and the amount of the one protic solvent relative to the total amount of the protic solvent Correlation with the ratio of
Obtaining at least one of the correlation between the intensity of the spectrum indicating the one protic solvent and the amount of the one protic solvent;
Correlation with the value calculated in the step of calculating at least one of the ratio of the intensity of the chemical shift value spectrum indicating only the one protic solvent and the intensity of the chemical shift value spectrum indicating only the one protic solvent. Based on the correlation acquired in the step of acquiring a relationship, the ratio of the one protic solvent amount to the total protic solvent amount of the specific location in the membrane, and the specific location in the membrane Calculating at least one of the amount of one protic solvent;
Outputting the value calculated in the step of calculating as the transmission characteristic;
A measurement method characterized by comprising:

  According to the present invention, there are provided a measuring apparatus, a measuring method, and a measuring method capable of calculating the permeation characteristics of a membrane protic solvent with high reliability.

The present invention relates to the permeation characteristics (proportion or amount of one protic solvent amount) of one protic solvent at a specific location in a membrane containing two or more protic solvents, and ease of movement of the protic solvent. The present invention relates to a measuring apparatus and a measuring method for measuring thickness (mobility).
First, in order to facilitate understanding of the present invention, the measurement principle of the present invention will be described.

(Measurement principle)
(A) The measurement principle of the permeation characteristics of one protic solvent (the ratio or amount of one protic solvent) at a specific location in a membrane containing two or more protic solvents,
and,
(B) The measurement principle of the easiness of movement of the protic solvent (mobility) will be described with an example.
Here, a solid polymer electrolyte membrane used for a direct methanol fuel cell is exemplified as the membrane.
This solid polymer electrolyte membrane contains methanol (CH ₃ OH) as a protic solvent and water (H ₂ O) as a protic solvent.

(A) Measurement of transmission characteristics Measurement of transmission characteristics is based on the nuclear magnetic resonance (NMR) method.
(I) Using a small RF coil smaller than the solid polymer electrolyte membrane, local measurement is performed,
(Ii) The obtained NMR signal is subjected to Fourier analysis to calculate methanol permeation characteristics at a specific location of the solid polymer electrolyte membrane.
Here, the ratio of the amount of methanol to the total amount of water and methanol in the solid polymer electrolyte membrane is calculated, and this is used as the transmission characteristics.

(I) Local measurement using a small RF coil The nuclear magnetic resonance (NMR) method can detect the motion of nuclear magnetization as an NMR signal by the spin resonance phenomenon of a nucleus placed in a magnetic field.
When calculating the permeation characteristics of methanol, a small RF coil is brought into contact with the solid polymer electrolyte membrane, an oscillating magnetic field for excitation is applied to the solid polymer electrolyte membrane, and a specific location in the solid polymer electrolyte membrane is selected. The NMR signal generated in is acquired by a small RF coil.
The spin resonance frequency in a magnetic field of 1 Tesla is about 43 MHz, and an LC resonance circuit is used to selectively detect the frequency band with high sensitivity.

  FIG. 6 is a diagram illustrating an example of a configuration of a coil portion (FIG. 7) of an LC resonance circuit described later in the embodiment. By making the coil portion (inductance portion) of the resonance circuit a small surface coil (small RF coil) and a planar “spiral type” coil, the measurement region can be limited and local measurement can be performed. The measurement region of such a spiral coil (small RF coil) has a width of about the diameter of the coil and a depth of about the coil radius. Further, since this coil (small RF coil) has a flat shape unlike a normal solenoid type coil, as shown in FIG. 6, only by attaching it on a flat solid polymer electrolyte membrane, NMR can be obtained. A signal can be acquired.

Here, the measurement region of the spiral coil (small RF coil) will be examined.
A single-turn small RF coil having a diameter of 10 mm and a wire diameter of 0.8 mm will be described as an example.
As shown in FIG. 1, the small RF coil is installed at a position of Y = 0 on the XZ plane of the coordinate system. When a predetermined current is passed through the installed small RF coil and a 90 ° excitation pulse is irradiated, as shown in FIG. 2, Y = 5 mm (corresponding to the radius of the small RF coil), X = -13 to +13 mm (small RF coil) It can be seen that the excitation angle α of the nuclear magnetization is 90 ° in the range of (corresponding to the diameter of the coil).
In FIG. 1, the static magnetic field H ₀ direction is a direction along the Z axis. The oscillating magnetic field is in the direction along the X axis.
2 indicates a range in which the excitation angle α of nuclear magnetization is 30 °, and a line of 60 ° indicates a range in which the excitation angle α of nuclear magnetization is 60 °. Similarly, a 90 ° line indicates a range where the excitation angle α of nuclear magnetization is 90 °.
If the small RF coil has a uniform reception sensitivity distribution, it is possible to receive an NMR signal having an intensity corresponding to the sin function (sin α) of the excitation angle.

On the other hand, when the nuclear magnetization is excited at 90 ° at all positions, the reception sensitivity of the small RF coil becomes a sensitivity distribution substantially similar to the distribution of the excitation intensity shown in FIG. That is, the reception sensitivity decreases as the distance from the center of the small RF coil increases.
Therefore, the distribution of the NMR signal received after excitation takes into account the distribution of the excitation intensity shown in FIG. 2 and the distribution of the reception sensitivity of the small RF coil, and the small RF coil is weighted by sin α × sin α. The intensity of the NMR signal is received.
That is, it can be seen that the measurement region of the small RF coil has a depth that is about the size of the small RF coil and a width that is about the diameter of the small RF coil. Therefore, it can be seen that local measurement is possible by using a small RF coil.
Here, it is considered that some variation occurs in the measurement region depending on the number of turns of the small RF coil, the wire diameter, and the like. However, it is estimated that the measurement area of the small RF coil does not vary greatly, and the measurement area of the small RF coil has a depth about the radius of the small RF coil and a width about the diameter of the small RF coil. Conceivable.

(Ii) Calculation of methanol permeation characteristics at specific locations of the membrane As described above, when calculating the permeation characteristics of methanol, a small RF coil is brought into contact with the solid polymer electrolyte membrane, and the solid polymer electrolyte membrane is Then, an excitation oscillating magnetic field is applied, and an NMR signal generated at a specific location in the solid polymer electrolyte membrane is acquired by a small RF coil.
Then, Fourier analysis is performed on the NMR signal obtained by the small RF coil.
Hydrogen nuclei have different resonance frequencies depending on the nuclide and structure of the chemical bond.
In the case of methanol, the resonance frequency differs between a hydrogen nucleus bonded to a C atom and a hydrogen nucleus bonded to an O atom. The resonance frequency of water hydrogen nuclei and the resonance frequency of hydrogen nuclei bonded to O atoms in methanol are substantially the same.
Therefore, by performing Fourier analysis on the NMR signal acquired by the small RF coil (see, for example, FIGS. 23 and 28 in Examples described later), the NMR signal is converted into a spectrum corresponding to the hydrogen nucleus bonded to the C atom, It can be separated into spectra corresponding to hydrogen nuclei bonded to O atoms (see FIGS. 24 and 29).
And it can be said that the spectrum which has the chemical shift value of the hydrogen nucleus couple | bonded with C atom is a spectrum which shows only methanol.

Here, when calculating the permeation characteristics of methanol,
Of the spectrum showing only methanol with respect to the sum of the spectrum intensities of water and methanol (the sum of the spectrum intensity of the hydrogen nucleus bonded to the C atom and the spectrum intensity of the hydrogen nucleus bonded to the H atom). The ratio of the intensity (the intensity of the spectrum of the hydrogen nucleus bonded to the C atom);
The ratio of the amount of methanol to the total amount of methanol and water;
Measure the correlation.

In other words, (the intensity of the spectrum corresponding to the hydrogen nucleus bonded to the C atom) / (the spectrum intensity corresponding to the hydrogen nucleus bonded to the C atom + the spectrum corresponding to the hydrogen nucleus bonded to the O atom) Strength), and
(Methanol amount) / (Methanol amount + Water amount)
(See FIG. 26).
Examples of a method for calculating this correlation include the following methods.
Prepare a solution whose methanol concentration and water concentration are known in advance.
An excitation oscillating magnetic field is applied to the solution by a small RF coil, and an NMR signal generated in the solution is acquired by the small RF coil.
Thereafter, the NMR signal obtained by the small RF coil is subjected to Fourier analysis.
And (intensity of spectrum corresponding to hydrogen nucleus bonded to C atom) / (intensity of spectrum corresponding to hydrogen nucleus bonded to C atom) + intensity of spectrum corresponding to hydrogen nucleus bonded to O atom ) Is calculated and associated with the ratio of the amount of methanol to the total amount of methanol and water (here, the ratio of methanol concentration).
Next, the same operation is performed by changing the concentration of the solution.
By doing in this way, the correlation mentioned above can be grasped | ascertained.

Next, from the NMR signal generated at a specific location in the solid polymer electrolyte membrane and obtained by the small RF coil, (intensity of spectrum corresponding to hydrogen nuclei bonded to C) / (coupled to C The spectral intensity corresponding to the hydrogen nuclei + the intensity of the spectrum corresponding to the hydrogen nuclei bonded to O) is calculated.
Then, based on the calculated value and the correlation calculated in advance, the methanol amount ratio is calculated.
Finally, the calculated ratio of the methanol amount is output as the methanol permeation characteristic at a specific location of the solid polymer electrolyte membrane.

Here, when calculating the correlation, an oscillating magnetic field for excitation was applied to the solution. In this case, the T2 ^* relaxation time constant of the NMR signal generated by the hydrogen nucleus bonded to the C atom is substantially the same as the T2 ^* relaxation time constant of the NMR signal generated by the hydrogen nucleus bonded to the O atom. It is believed that there is.
However, when an oscillating magnetic field for excitation is applied to the solid polymer electrolyte membrane, the T2 ^* relaxation time constant of the NMR signal generated by the hydrogen nuclei bonded to C atoms and the hydrogen nuclei bonded to O atoms The T2 ^* relaxation time constant of the NMR signal generated by may be different.
In this case, it becomes difficult to calculate the ratio of the amount of methanol using the correlation acquired based on the solution.
In such a case, the solid polymer electrolyte membrane is immersed in a solution (methanol + water solution) whose methanol concentration is known in advance. By immersing the solid polymer electrolyte membrane in the solution for a long time, the ratio of methanol amount (methanol concentration ratio) in the solid polymer electrolyte membrane becomes equal to the methanol amount ratio (methanol concentration ratio) in the solution. Conceivable.
Next, an oscillating magnetic field for excitation is applied to the solid polymer electrolyte membrane immersed in the solution by a small RF coil, and a nuclear magnetic resonance signal is acquired. And based on the nuclear magnetic resonance signal acquired with the small RF coil, while acquiring the intensity | strength of the spectrum corresponding to the hydrogen nucleus couple | bonded with C atom, (the spectrum corresponding to the hydrogen nucleus couple | bonded with C atom) Intensity) / (spectrum intensity corresponding to hydrogen nuclei bonded to C atoms + spectrum intensity corresponding to hydrogen nuclei bonded to O atoms) is calculated. Thereafter, the calculated value is correlated with the ratio of the amount of methanol in the solid polymer electrolyte membrane immersed in the solution (ratio of methanol concentration).
Next, the same operation is performed by changing the ratio of the methanol concentration of the solution in which the solid polymer electrolyte membrane is immersed.
Thereby, in the solid polymer electrolyte membrane, (the intensity of the spectrum corresponding to the hydrogen nucleus bonded to the C atom) / (the spectrum intensity corresponding to the hydrogen nucleus bonded to the C atom + the O atom) It is possible to grasp the correlation between the intensity of the spectrum corresponding to the hydrogen nucleus and (amount of methanol) / (amount of methanol + amount of water).

Here, the ratio of the amount of methanol to the total amount of methanol and water is calculated as the methanol permeation characteristics, but the present invention is not limited to this, and the amount of methanol (absolute amount of methanol) may be calculated.
In this case, the correlation between the intensity of the spectrum indicating methanol (the intensity of the spectrum of the hydrogen nucleus bonded to the C atom) and the amount of methanol is grasped in advance.
And the intensity | strength of the spectrum which shows only methanol is acquired from the NMR signal obtained by the small RF coil, and the quantity of methanol should just be calculated based on the said correlation.

Next, calculation of mobility will be described.
(B) Calculation of mobility In order to locally measure the mobility of a specific part of the solid polymer electrolyte membrane, a PGSE (Pulsed-Gradient Spin-Echo) method is used.
After exciting specific nuclear spins by magnetic resonance and applying a pair of gradient magnetic field pulses (pulsed gradient magnetic field) at intervals of several tens of ms, individual nuclei move between them by Brownian motion or diffusion. Since it moves and the phase of the nuclear spin does not converge, the intensity of the NMR signal decreases. The self-diffusion coefficient of a specific molecular species, such as methanol, can be measured by associating the gradient magnetic field pulse changed stepwise with the decrease in the intensity of the NMR signal.
FIG. 3 is a diagram illustrating an example of a PGSE sequence used for measuring the self-diffusion coefficient. In the sequence in FIG. 3, a pair of gradient magnetic field pulses Gz having the same intensity as the application time are added to a normal spin echo sequence with a 180 ° excitation pulse as the axis of symmetry, and for example, a spin echo signal is acquired as an NMR signal. The peak intensity S of the NMR signal depends on the applied pulse gradient magnetic field intensity Gz [gauss / m], the application time d, and the pulse interval Δ, and the self-diffusion coefficient Dz [m ² / s].
ln (S / S ₀ ) = − γ ² DzΔ ² dGz ² (I)

In the above formula (I), S ₀ represents a normal NMR signal intensity when Gz = 0. Further, d, Δ, and Gz represent the pulse width of the gradient magnetic field pulse, the time interval between the pair of gradient magnetic field pulses, and the magnetic field gradient of the gradient magnetic field pulse, respectively. Γ represents the gyromagnetic ratio and is a value specific to the nucleus. S ₀ is the peak intensity of the NMR signal when Gz = 0 when no gradient magnetic field is applied, and γ is the gyromagnetic ratio of the target hydrogen nucleus 42.577 × 10 ² [1 / gauss · s].

  FIG. 3 illustrates a sequence in the case of d = 1.5 ms and Δ = 34.5 ms. For example, by applying a magnetic field to the solid polymer electrolyte membrane in such a pulse sequence, the self-diffusion coefficient Dz can be stably calculated using the peak intensity S of the NMR signal as the NMR signal.

FIG. 4 is a flowchart for locally measuring the mobility of a specific portion of the solid polymer electrolyte membrane using the PGSE method as described above, and includes the following steps.
First, a solid polymer electrolyte membrane is placed in a static magnetic field created by a magnet or the like, and a static magnetic field is applied to the solid polymer electrolyte membrane. In this state, an excitation oscillating magnetic field is applied to the solid polymer electrolyte membrane, and an NMR signal corresponding to this is acquired (S202). No gradient magnetic field is applied. Step 202 includes the following steps.
A first step of applying an excitation oscillating magnetic field to the solid polymer electrolyte membrane according to a predetermined pulse sequence; and
A second step of acquiring an NMR signal corresponding to the pulse sequence of the first step.

Next, a gradient magnetic field is applied to the same region in the solid polymer electrolyte membrane, and step 204 is executed to acquire an NMR signal. In step 204, the following third step and fourth step are executed once or a plurality of times.
A third step of applying the excitation oscillating magnetic field and gradient magnetic field according to a predetermined pulse sequence; and
A fourth step for acquiring an NMR signal corresponding to the pulse sequence of the third step

  In the first step and the third step, a local magnetic field is applied to a specific portion of the solid polymer electrolyte membrane using a small RF coil smaller than the solid polymer electrolyte membrane. In the second step and the fourth step, an NMR signal is acquired from a specific portion of the solid polymer electrolyte membrane using a small RF coil smaller than the solid polymer electrolyte membrane.

In FIG. 4, an example in which the gradient magnetic field is not applied is shown in the first step, but a predetermined gradient magnetic field having a magnitude different from that of the third step may be applied in the first step. At this time, for example, it is preferable to set the magnitude of the gradient magnetic field in the first step to a value close to zero.
Subsequently, the self-diffusion coefficient D is calculated from a plurality of NMR signals obtained by changing the gradient of the pulse gradient magnetic field stepwise (S206). In step 206, the self-diffusion coefficient D of a specific portion of the solid polymer electrolyte membrane is calculated based on the information of the NMR signal obtained in the second step and the information of the NMR signal obtained in the fourth step. . Thereafter, the result is output (S208).

Details of each step will be described below.
(I) Step 202 and Step 204 (application of excitation oscillating magnetic field, application of gradient magnetic field and acquisition of NMR signal)
In step 202 and step 204, an oscillating magnetic field for excitation and a gradient magnetic field are applied to the solid polymer electrolyte membrane according to a predetermined sequence. Specifically, as described above, in step 202, the gradient magnetic field is set to zero or a value close to zero, and in step 204, a predetermined gradient magnetic field is applied.

The excitation oscillating magnetic field is a pulse sequence composed of a plurality of pulses, and the gradient magnetic field is a pair of pulse sequences corresponding to the excitation oscillating magnetic field. The pulse sequence is preferably composed of the following (a) to (d).
(A) 90 ° pulse of an oscillating magnetic field for excitation,
(B) A gradient magnetic field pulse that starts after the elapse of the pulse time of (a) and is applied for a fixed time d,
(C) a 180 ° pulse of an oscillating magnetic field for excitation applied after elapse of time τ of the pulse of (a), and
(D) A gradient magnetic field pulse that starts after the elapse of the pulse time of (c) and is applied for a predetermined time d.
Referring to FIG. 3, the time when the application of the gradient magnetic field pulse in (b) is completed and the time when the application of the gradient magnetic field pulse in (d) is started are the 180 ° pulses (pulses) in (c). However, it has a width of 120 microseconds, and the distance of 60 microseconds at the center is considered as the axis of symmetry, and is separated by an equal time ((34.5 ms−1.5 ms) /2=16.5 ms). Furthermore, the gradient magnetic field pulse application time d in (b) and the gradient magnetic field pulse application time d in (d) are both made equal (d = 1.5 ms).

Then, an NMR signal corresponding to the pulse sequence is measured. The peak intensity S of the NMR signal is measured by a spin echo method.
Specifically, as shown in FIG. 3, the peak intensity S of the echo signal that appears at 2τ time is measured. The peak intensity S may be not only the NMR signal intensity for 2τ hours, but also the average value of the NMR signal intensity measured in the surrounding time. By this method, it is possible to reduce variations in measured values caused by noise included in the NMR signal.

  In this embodiment, the gradient self-diffusion coefficient D in the solid polymer electrolyte membrane is determined by detecting the degree of decrease in the NMR signal corresponding to the case where the gradient magnetic field is applied stepwise to increase the magnetic field gradient. calculate.

(Ii) Step 206 (Measurement of self-diffusion coefficient D)
In step 206, the self-diffusion coefficient D is obtained from the peak intensity of the NMR signal. The proton self-diffusion coefficient D is expressed by the above-described formula (I) using the peak intensity S of the NMR signal acquired by the PGSE method.
From the peak intensity S ₀ of the NMR signal when the gradient magnetic field G is not applied and the peak intensity S of the NMR signal when the gradient magnetic field G is applied, in the solid polymer electrolyte membrane using the above formula (I) The self-diffusion coefficient D of protons can be obtained. For example, by changing the magnitude of the same gradient magnetic field G in the solid polymer electrolyte membrane and measuring, and plotting the relationship between ln (S / S ₀ ) and −γ ² DΔ ² dG ² , the gradient of the plot From this, the self-diffusion coefficient D can be obtained.

  Hereinafter, an example of a transmission characteristic measurement method, a mobility measurement method based on the above-described principle, and an apparatus that implements these methods will be described.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar constituent elements are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
(First embodiment)
FIG. 5 is a diagram showing a schematic configuration of the measuring apparatus 1 according to the present embodiment.
This measuring apparatus 1 uses NMR to transmit a protic solvent (methanol in the present embodiment) at a specific location in a membrane (solid polymer electrolyte membrane 115) containing water as a protic solvent and methanol. This is a device capable of measuring characteristics and mobility (in this embodiment, self-diffusion coefficient).

The measuring device 1
A sample mounting table 116 on which the solid polymer electrolyte membrane 115 is mounted;
A static magnetic field application unit (magnet 113) for applying a static magnetic field to the solid polymer electrolyte membrane 115;
A gradient magnetic field application unit (G coil 151 (first G coil 151A, second G coil 151B)) for applying a gradient magnetic field to the solid polymer electrolyte membrane 115;
A small RF coil 114 smaller than the solid polymer electrolyte membrane 115, which applies an oscillating magnetic field for excitation to the solid polymer electrolyte membrane 115 and acquires NMR signals corresponding to the oscillating magnetic field and gradient magnetic field for excitation,
Switching the measurement mode to switch between the first measurement mode for measuring the transmission characteristics by applying the excitation oscillating magnetic field and the second measurement mode for measuring the self-diffusion coefficient by applying the gradient magnetic field and the oscillating magnetic field for excitation. Control unit 169,
Based on the nuclear magnetic resonance signal acquired by the small RF coil 114, a spectrum of a chemical shift value indicating only methanol is acquired, and permeation of methanol at a specific location in the solid polymer electrolyte membrane 115 is acquired based on the intensity of this spectrum. A calculation device 130 having a transmission characteristic calculation unit 132 for calculating characteristics, and a self-diffusion coefficient calculation unit (mobility calculation unit) 133 for calculating the self-diffusion coefficient of methanol at a specific location of the solid polymer electrolyte membrane 115;
Is provided.

First, the device configuration around the solid polymer electrolyte membrane 115 and the solid polymer electrolyte membrane 115 will be described.
The solid polymer electrolyte membrane 115 contains two or more kinds of protic solvents. In this embodiment, the polymer electrolyte membrane 115 contains water (H ₂ O) and methanol (CH ₃ OH). This solid polymer electrolyte membrane 115 is incorporated in a direct methanol fuel cell.

The magnet 113 applies a static magnetic field to the entire solid polymer electrolyte membrane 115. With this static magnetic field applied, an excitation oscillating magnetic field is applied to the solid polymer electrolyte membrane 115, and the transmission characteristics of the solid polymer electrolyte membrane 115 are measured.
In addition, an excitation oscillating magnetic field and a gradient magnetic field pulse are applied to the solid polymer electrolyte membrane 115 in a state where a static magnetic field is applied to the solid polymer electrolyte membrane 115, and the self-diffusion coefficient is measured.

  The small RF coil 114 applies an excitation oscillating magnetic field to a specific portion of the solid polymer electrolyte membrane 115. Further, an NMR signal corresponding to the excitation oscillating magnetic field and an NMR signal corresponding to the gradient magnetic field are acquired.

  The small RF coil 114 is preferably ½ or less, more preferably 1/10 or less of the entire size of the solid polymer electrolyte membrane 115. By using such a size, it becomes possible to accurately measure the local mobility of methanol and the permeation characteristics of methanol in the solid polymer electrolyte membrane 115 in a short time. The size of the solid polymer electrolyte membrane 115 can be, for example, a projected area when the solid polymer electrolyte membrane 115 is placed, and the exclusive area of the small RF coil 114 is preferably the projected area. By setting it to 1/2 or less, more preferably 1/10 or less, accurate measurement can be performed in a short time. The size of the small RF coil 114 is preferably, for example, 10 mm or less in diameter.

  As the small RF coil 114, for example, a planar spiral coil as shown in FIG. 6 can be used, and the measurement region can be limited by using such a planar coil.

The excitation oscillating magnetic field H ₁ applied by the small RF coil 114 that is a flat spiral coil needs to be perpendicular to the static magnetic field H ₀ applied by the magnet 113 (see FIGS. 9 and 10).

  The oscillating magnetic field (exciting oscillating magnetic field) applied by the small RF coil 114 is a combination of the RF oscillator 102, the modulator 104, the RF amplifier 106, the pulse control unit 108 (see FIG. 11), the switch unit 161, and the small RF coil 114. Is generated by That is, the excitation oscillating magnetic field oscillated from the RF oscillator 102 is modulated by the modulator 104 based on the control by the pulse control unit 108 and becomes a pulse shape. The generated RF pulse is amplified by the RF amplifier 106 and then transmitted to the small RF coil 114. The small RF coil 114 applies this RF pulse to a specific portion of the solid polymer electrolyte membrane 115 placed on the sample placement table 116. And the small RF coil 114 detects the NMR signal emitted with respect to the applied RF pulse. This NMR signal is amplified by the preamplifier 112 and then sent to the phase detector 110. The phase detector 110 detects this NMR signal and sends it to the A / D converter 118. The A / D converter 118 A / D-converts the NMR signal and sends it to the arithmetic unit 130.

  The application of the excitation oscillating magnetic field and the detection of the NMR signal have been described above, but these can be realized by an LC circuit including a small RF coil. FIG. 7 is a diagram illustrating an example of such an LC circuit. The coil portion (inductance portion) of the resonance circuit is a small RF coil having a diameter of 2.0 mm. In the nuclear magnetic resonance (NMR) method, the motion of nuclear magnetization can be detected as an NMR signal by the spin resonance phenomenon of nuclei placed in a magnetic field. The spin resonance frequency in a magnetic field of 1 Tesla is about 43 MHz, and an LC resonance circuit as shown in FIG. 7 is used to selectively detect the frequency band with high sensitivity.

  The switch part 161 is provided in the branch part which connects the small RF coil 114, the RF excitation pulse generation part, and the NMR signal detection part.

  The RF excitation pulse generation unit includes an RF oscillator 102, a modulator 104, and an RF amplifier 106, and generates an RF excitation pulse that causes the small RF coil 114 to generate an oscillating magnetic field for excitation. The NMR signal detection unit includes a preamplifier 112, a phase detector 110, and an A / D converter 118, detects the NMR signal acquired by the small RF coil 114, and sends the NMR signal to the arithmetic device 130.

The switch unit 161 is
A first state in which the small RF coil 114 and the RF excitation pulse generator (RF amplifier 106) are connected; and
It has a function of switching the second state in which the small RF coil 114 and the NMR signal detector (phase detector 110) are connected.

  The switch unit 161 serves as such a “transmission / reception switching switch”. The role is to transmit the excitation pulse amplified by RF power-amp to the small RF coil 114 to separate the preamplifier 112 of the receiving system and protect it from a large voltage, and to receive the NMR signal after excitation. In other words, the noise generated by the large amplification transistor leaking from the RF amplifier 106 is blocked from being transmitted to the preamplifier 112 of the receiving system. When measurement is performed using the small RF coil 114, a weak signal is handled, so the switch unit 161 is necessary for the following reason. On the other hand, in a large measurement system that does not use the small RF coil 114, the use of a “cross diode” can sufficiently cope. The cross diode is a diode that is turned on when a voltage equal to or higher than a predetermined value is applied and is turned off when the voltage is lower than the predetermined value.

The reason why the “transmission / reception changeover switch”, that is, the switch unit 161 is particularly necessary when the small RF coil 114 is used is as follows.
(I) The volume of a specific location in the film that can be detected by the small RF coil 114 of the present measurement system is smaller than that of the large coil. This detectable volume is approximately (coil inner area × coil radius depth). In order to measure a weak NMR signal that decreases in proportion to the volume with low noise and high sensitivity, it is necessary to block noise leaking from the large amplification transistor of the RF amplifier 106 in the transmission system. . In the receiving system, it is necessary to use a highly sensitive preamplifier 112. In using the high-sensitivity preamplifier 112, the preamplifier 112 must be disconnected so that the preamplifier 112 can be protected from a high-voltage excitation pulse sent to a small coil during transmission.
(Ii) When measuring the mobility, the nuclear magnetization in the volume at a specific location in the film is excited. At this time, with an appropriate excitation pulse power, specifically, a 90 degree pulse and a 180 degree pulse It is necessary to excite nuclear magnetization so that the intensity of the pulse is 1: 2. If the excitation pulse power cannot be adjusted properly, the target spin-echo pulse sequence will not be obtained, and as a result, an appropriate spin-echo signal cannot be acquired. Decreases. This phenomenon is prominent when switching between transmission and reception of a small coil using a conventional cross diode. In the case of a large coil, the excitation pulse intensity is very large and the loss in the cross diode can be considered to be negligibly small, but in the case of a small coil, the excitation pulse intensity is smaller than that of the large coil, so The loss of can not be ignored. For this reason, in order to obtain an appropriate excitation pulse intensity, a “transmission / reception selector switch” with as little loss as possible is required. By providing the switch part 161 at the branch part, the loss of the oscillating magnetic field signal for excitation applied from the small RF coil 114 to the solid polymer electrolyte membrane 115 is reduced. As a result, the pulses of 90 ° pulse and 180 ° pulse are reduced. It becomes possible to control the angle accurately. Accurate control of the pulse angle is an important technical problem in reliably obtaining a compensation effect in the spin echo method. In the present embodiment, this problem is solved by the arrangement of the switch unit 161.

  In addition, since the RF detection coil for local measurement is miniaturized, a reduction in noise during NMR reception is an important factor for ensuring the accuracy of measurement. When receiving an NMR signal, noise that enters the preamplifier 112 mainly includes an RF wave transmission system, which is caused by “RF wave leakage” or “high power amplifier” from the RF amplifier 106 that amplifies the excitation pulse. There is "noise". When receiving the NMR signal, it is necessary to reliably block the excitation wave leaking from the transmission side by the switch unit 161 and receive the NMR signal with low noise. In the present embodiment, this problem is also solved by the arrangement of the switch unit 161.

  The switch unit 161 can employ various configurations. FIG. 8 is a circuit diagram showing an example of the configuration of the switch unit 161.

As shown in FIGS. 9 and 10, the first G coil 151 </ b> A and the second G coil 151 </ b> B are arranged so that a gradient magnetic field can be applied to the solid polymer electrolyte membrane 115.
The first G coil 151A and the second G coil 151B are attached to the support 201 together with the small RF coil 114 described above.
The support 201 has a stick shape, and in the present embodiment, has a cylindrical shape. A first G coil 151A, a small RF coil 114, and a second G coil 151B are attached to the end surface 201B of the tip 201C of the support 201.
In addition, the conducting wire (not shown) connected to the small RF coil 114, the conducting wire (not shown) connected to the first G coil 151A, and the conducting wire connected to the second G coil 151B are accommodated inside the support body 201. .
Various shapes can be adopted for the first G coil 151A and the second G coil 151B, but in this embodiment, a flat coil is used. The first G coil 151 </ b> A and the second G coil 151 </ b> B have a half-moon shape in the present embodiment, and half-moon strings are arranged opposite to each other with the small RF coil 114 interposed therebetween.
The first G coil 151A and the second G coil 151B are arranged in parallel to the surface (xz plane) of the solid polymer electrolyte membrane 115.
The small RF coil 114 protrudes toward the solid polymer electrolyte membrane 115 from the first G coil 151A and the second G coil 151B.
More specifically, a columnar protrusion 201A protruding toward the solid polymer electrolyte membrane 115 is provided at the center of the end surface 201B of the tip 201C of the support 201, and the end surface of the protrusion 201A is provided on the end surface of the protrusion 201A. A small RF coil 114 is attached. The plane center of the small RF coil 114 and the center axis of the support 201 are substantially coincident. And the 1st G coil 151A and the 2nd G coil 151B are attached to both sides on both sides of this projection part 201A.
Thus, by arranging the first G coil 151A and the second G coil 151B above the small RF coil 114, a gradient magnetic field having a gradient in the y-axis direction can be stably formed on the central axis of the small RF coil 114. Can be formed.
Further, when measuring the transmission characteristics and self-diffusion coefficient of the solid polymer electrolyte membrane 115 by causing the small RF coil 114 to protrude toward the solid polymer electrolyte membrane 115 side from the first G coil 151A and the second G coil 151B. Only the small RF coil 114 can be brought into contact with the solid polymer electrolyte membrane 115.
When measuring the transmission characteristics and self-diffusion coefficient of the solid polymer electrolyte membrane 115, the small RF coil 114 may be brought into direct contact with the solid polymer electrolyte membrane 115, or through a thin cover glass or the like. Indirect contact may also be made.

As shown in FIG. 5, the application of a high frequency pulse from the RF oscillator 102 to the small RF coil 114 via the modulator 104 and the pulse current to the first G coil 151A and the second G coil 151B via the current drive power source 159 are applied. The supply is controlled by the measurement mode switching control unit 169. Measurement mode switching control unit 169 includes a measurement mode selection unit 169A and a control unit 169B.
The measurement mode selection unit 169A receives a request input by an operator and selects a measurement mode according to the received request. In the present embodiment, the first measurement mode for measuring the methanol permeation characteristics at a specific location in the solid polymer electrolyte membrane 115, the mobility of the methanol at a specific location in the solid polymer electrolyte membrane 115 (self-diffusion coefficient). One of the measurement modes is selected from the second measurement modes for measuring.

  FIG. 11 is a diagram illustrating a configuration example of the control unit 169B. The control unit 169B includes a pulse control unit 108 that controls the operation of the modulator 104 and a gradient magnetic field control unit 171 that controls the operation of the current driving power source 159.

A sequence table 127 is connected to the control unit 169B, and the sequence table 127 stores sequence data for determining a sequence of a pulse current that generates a high-frequency pulse and a gradient magnetic field when measuring a self-diffusion coefficient. Yes. That is, a timing diagram in which the time for generating the pulse current for the high-frequency pulse and the gradient magnetic field and the interval thereof in the case of measuring the self-diffusion coefficient is stored.
The sequence table 127 also stores the application time of the high-frequency pulse when measuring the transmission characteristics.
Further, the sequence table 127 stores the intensity of the high frequency pulse applied when measuring the transmission characteristics. Further, the sequence table 127 also stores the intensity of the high frequency pulse and the gradient magnetic field pulse current applied based on the timing diagram.
In addition, a timer unit 128 is connected to the control unit 169B.

Such a control unit 169B generates a high-frequency pulse and a pulse current for the gradient magnetic field based on the sequence data obtained from the sequence table 127 and the measurement time in the time measuring unit 128.
For example, when the operator inputs a request to perform both transmission characteristic measurement and self-diffusion coefficient measurement, the operation signal receiving unit 129 connected to the measurement mode switching control unit 169 receives the request. Then, the operation signal receiving unit 129 sends this request to the measurement mode switching control unit 169. The measurement mode selection unit 169A selects a measurement mode for measuring the transmission characteristics, and sends information for specifying the selected measurement mode to the control unit 169B and the data reception unit 131. The data receiving unit 131 sends this measurement mode specifying information to the arithmetic device 130. The arithmetic device 130 performs corresponding arithmetic processing based on the measurement mode specifying information.
Here, if the measurement mode specifying information indicates the first measurement mode for measuring the transmission characteristic, the measurement data is sent to the transmission characteristic calculating unit 132, and the measurement mode specifying information is used for the second measurement for measuring the self-diffusion coefficient. If the mode is indicated, the measurement data is sent to the self-diffusion coefficient calculation unit 133, and predetermined processing is executed in each calculation unit.
The control unit 169B, which has obtained the measurement mode specifying information for measuring the transmission characteristics, reads the transmission characteristic measurement data from the sequence table 127. Then, the pulse control unit 108 of the control unit 169B controls the operation of the modulator 104, and applies an excitation oscillating magnetic field to the solid polymer electrolyte membrane 115.

Next, measurement mode selection section 169A selects a measurement mode for measuring the self-diffusion coefficient, and sends measurement mode specifying information corresponding to this selection to control section 169B and data reception section 131. The data reception unit 131 sends measurement mode specifying information indicating the measurement mode selected by the measurement mode selection unit 169A to the calculation device 130, and the self-diffusion coefficient calculation unit 133 of the calculation device 130 selects the measurement mode selection unit 169A. Measurement mode specifying information indicating the mode is received.
The control unit 169B reads the sequence data for measuring the self diffusion coefficient from the sequence table 127. The pulse control unit 108 of the control unit 169B controls the operation of the modulator 104, and the gradient magnetic field control unit 171 controls the operation of the current driving power source 159.
The excitation oscillating magnetic field is applied to the solid polymer electrolyte membrane 115 according to a predetermined pulse sequence, and the excitation oscillating magnetic field and the gradient magnetic field are applied according to a predetermined pulse sequence.

Note that the order of measurement of the transmission characteristics and the measurement of the self-diffusion coefficient is not particularly limited, and the self-diffusion coefficient may be measured before the measurement of the transmission characteristics.
Further, when the operator inputs a request to perform only transmission characteristic measurement or only self-diffusion coefficient measurement, based on this request, the measurement mode selection unit 169A of the measurement mode switching control unit 169 A first measurement mode for measuring the transmission characteristics or a second measurement mode for measuring the self-diffusion coefficient can be selected.

The current driving power source 159 shown in FIG. 5 is used to supply current to the first G coil 151A and the second G coil 151B. The current driving power source 159 does not use a switching power source, and a transformer or the like is used. I use it.
Further, when the current driving power source 159 is not driven, the transistor is controlled so as not to oscillate minutely due to noise.
Further, it is possible to adopt a structure in which the conductors connected to the first G coil 151A and the second G coil 151B are cut off in a state where the current driving power source 159 is not driven.
By using the current driving power source 159 having such a configuration, the influence of noise from the current driving power source 159 on the NMR signal can be prevented.

  The apparatus configuration around the solid polymer electrolyte membrane 115 has been described above. Next, an NMR signal processing block will be described.

As shown in FIG. 5, the calculation device 130 includes a transmission characteristic calculation unit 132 and a self-diffusion coefficient calculation unit 133.
First, the transmission characteristic calculator 132 will be described with reference to FIG.
From the intensity of the NMR signal obtained by applying an excitation oscillating magnetic field to the solid polymer electrolyte membrane 115, the transmission characteristic calculator 132 determines the ratio of methanol at a specific location of the solid polymer electrolyte membrane 115 (in this embodiment, , The molar fraction of the amount of methanol with respect to the total amount of methanol and water).
The transmission characteristic calculation unit 132 includes a calculation unit 136 including a data analysis unit 134 and a calculation unit 135, and a storage unit 137.
In the storage unit 137,
Methanol mole fraction (methanol moles / (methanol moles + water moles)),
Spectra showing only methanol (total of hydrogen nuclei bound to C atoms) relative to the sum of the intensities of water and methanol spectra (intensity of hydrogen nuclei bound to C atoms and spectrum of hydrogen nuclei bound to O atoms) Spectrum) intensity ratio,
Is stored (see FIG. 26).

Based on the FID signal acquired by the small RF coil 114, the calculation unit 136 acquires a spectrum caused by water and methanol at a specific location of the solid polymer electrolyte membrane 115.
Then, the ratio of the intensity of the spectrum showing only methanol to the total value of the intensity of the spectrum caused by water and methanol at a specific location of the solid polymer electrolyte membrane 115 is calculated.
Furthermore, the calculation unit 136 calculates the molar fraction of methanol based on the correlation stored in the storage unit 137.
The data analysis unit 134 of the calculation unit 136 performs Fourier analysis on the FID signal (see FIG. 28) acquired by the small RF coil 114 (see FIG. 29).
The calculation unit 135 of the calculation unit 136 acquires the result analyzed by the data analysis unit 134, and detects the spectrum indicating only methanol, that is, the spectrum corresponding to the chemical shift value of the hydrogen nucleus bonded to the C atom.
Then, the intensity of the spectrum of the hydrogen nucleus bonded to the C atom is calculated.
The calculation unit 135 also detects the intensity of the spectrum corresponding to the chemical shift value of the hydrogen nucleus bonded to the O atom.
Next, a spectrum showing only methanoe with respect to the total value of the spectrum of water and methanol (the total of the spectrum intensity of the hydrogen nucleus bonded to the C atom and the spectrum intensity of the hydrogen nucleus bonded to the O atom) ( The ratio of the intensity of the hydrogen nucleus spectrum bonded to the C atom is calculated.
Thereafter, the storage unit 137 is referred to, and the molar fraction of methanol corresponding to the calculated ratio is acquired.
Thereby, the mole fraction of methanol as the methanol permeation characteristic of the solid polymer electrolyte membrane 115 can be grasped.
Note that the calculation unit 135 may calculate not only the molar fraction of methanol but also the molar fraction of water.

  As described above, the calculated mole fraction of methanol is output from the output unit 138 as methanol permeation characteristics of the solid polymer electrolyte membrane 115 and presented to the user. Various types of presentation types are possible, and there are no particular restrictions on display on the display, printer output, file output, and the like.

Next, the self-diffusion coefficient computing unit 133 that calculates mobility will be described with reference to FIGS. 13 and 14.
As described above, the mobility is a physical property value indicating the ease of movement of the protic solvent in the solid polymer electrolyte membrane 115, and includes, for example, a self-diffusion coefficient and a mobility. In the embodiment, a self-diffusion coefficient is calculated as mobility.
The self-diffusion coefficient computing unit 133 is based on the NMR signal obtained by applying an excitation oscillating magnetic field to the solid polymer electrolyte membrane 115 and the NMR signal obtained by applying a different gradient magnetic field. Then, the self-diffusion coefficient of methanol molecules at a specific location of the solid polymer electrolyte membrane 115 is calculated.
The self-diffusion coefficient calculation unit 133 includes a data selection unit 133A, a self-diffusion coefficient calculation unit 133B, and a parameter table 133C for data selection.
The data sorting unit 133A sorts the NMR signals while referring to the data sorting parameter table 133C.
The NMR signal received by the data receiving unit 131 is sorted into an NMR signal having a predetermined intensity or higher and an NMR signal having a predetermined intensity or lower. Then, only an NMR signal having a predetermined intensity or higher is selected, the logarithm of the intensity of the NMR signal is taken, and linear approximation is performed by the least square method. Thereafter, it is determined whether or not the difference between the approximate line and the logarithm of the intensity of the NMR signal equal to or greater than a predetermined intensity is equal to or less than a predetermined value.
When the difference between the approximate straight line and the logarithm of the intensity of the NMR signal equal to or higher than the predetermined intensity is equal to or smaller than the predetermined value, the NMR signal equal to or higher than the predetermined intensity is transmitted to the self-diffusion coefficient calculating unit 133B Is calculated.
In addition, since the logarithm of the intensity of the NMR signal decreases exponentially, the logarithm of the intensity of the NMR signal acquired after a lapse of a certain time becomes substantially constant. The data selection unit 133A selects only the NMR signal before the logarithm becomes constant without selecting the NMR signal whose logarithm becomes constant.

As shown in FIG. 14, the self-diffusion coefficient calculation unit 133B includes a self-diffusion coefficient estimation unit 133D that calculates a self-diffusion coefficient, a correction unit 133F, and a correction parameter storage unit 133H.
The self-diffusion coefficient estimation unit 133D calculates an estimated value of the self-diffusion coefficient from the acquired NMR signal using the above-described formula (I).
In the correction unit 133F, the estimated value of the self diffusion coefficient calculated by the self diffusion coefficient estimation unit 133D is corrected according to the size of the small RF coil 114. In the correction parameter storage unit 133H, correction parameters or correction formulas related to correction in the correction unit 133F are stored.

  In the self-diffusion coefficient estimating unit 133D, the estimated value of the self-diffusion coefficient of methanol is calculated from the NMR signal detected by the small RF coil 114, but the small RF coil 114 that applies the excitation oscillating magnetic field is small. The measurement value may be different from the measurement using a large solenoid coil.

  In such a case, the correction unit 133F can correct the value of the self-diffusion coefficient as necessary. The correction parameter storage unit 133H stores a correction parameter and a correction method according to the size of the small RF coil 114, and the correction unit 133F acquires the information from the correction parameter storage unit 133H and performs correction. .

Next, the use of the measuring apparatus 1 as described above will be described.
By using the measuring device 1, it is possible to measure the methanol permeation characteristics and the self-diffusion coefficient at specific locations on the solid polymer electrolyte membrane 115 of the fuel cell during power generation.
When measuring the permeation characteristics and self-diffusion coefficient of the solid polymer electrolyte membrane 115 of the fuel cell during power generation, the small RF coil 114, the first G coil 151A, and the second G coil 151B are connected to the air electrode of the solid polymer electrolyte membrane 115. Install on the front side. At this time, the small RF coil 114 is brought into contact with the solid polymer electrolyte membrane 115.
By applying an oscillating magnetic field for excitation to the solid polymer electrolyte membrane 115 by the small RF coil 114 and acquiring an NMR signal generated at a specific location in the solid polymer electrolyte membrane 115 by the small RF coil 114. The ratio of the amount of methanol at a specific location of the solid polymer electrolyte membrane 115 can be grasped.
In addition, an excitation oscillating magnetic field is applied to the solid polymer electrolyte membrane 115 by the small RF coil 114, and a gradient magnetic field is applied by the G coil 151. And by acquiring the NMR signal generated corresponding to these magnetic fields by the small RF coil 114, the self-diffusion coefficient of methanol can be grasped.

Thus, by grasping the ratio of the amount of methanol at a specific location of the solid polymer electrolyte membrane 115 of the fuel cell during power generation, the solid polymer electrolyte membrane 115 of the fuel cell during power generation, for example, locally crosses. It is possible to discover that over has occurred. In this case, the amount of methanol supplied on the fuel electrode side of the fuel cell is adjusted so that the occurrence of crossover is minimized, and the concentration of methanol on the fuel electrode side of the fuel cell is adjusted to be low. Good.
In addition, in the solid polymer electrolyte membrane 115 of the fuel cell during power generation, in order to increase the power generation amount when the ratio of the amount of methanol is equal to or less than a predetermined value and there is no specific portion where a crossover occurs. The amount of methanol supplied on the fuel electrode side of the fuel cell may be increased.
Further, by grasping the self-diffusion coefficient of methanol at a specific location of the solid polymer electrolyte membrane 115 of the fuel cell during power generation, it becomes possible to adjust the supply amount of methanol more optimally.

In addition, by using the measuring apparatus 1 as described above, the performance (crossover characteristics) of the solid polymer electrolyte membrane 115 can be evaluated.
For example, it is possible to evaluate the performance of the solid polymer electrolyte membrane 115 in the previous stage of incorporation into the fuel cell.
When evaluating the crossover characteristic of the solid polymer electrolyte membrane 115, the small RF coil 114 is brought into contact with the surface of the solid polymer electrolyte membrane 115.
Then, the methanol permeability and self-diffusion coefficient are measured in the same manner as when measuring the methanol permeability and self-diffusion coefficient at specific locations on the solid polymer electrolyte membrane 115 of the fuel cell during power generation.
When the ratio of the amount of methanol at a specific portion of the solid polymer electrolyte membrane 115 is high, it is generally considered that the solid polymer electrolyte membrane 115 is a membrane in which crossover is likely to occur when incorporated in a fuel cell. Therefore, it can be estimated that the solid polymer electrolyte membrane 115 has poor crossover characteristics.
In addition, when the ratio of the amount of methanol at a specific portion of the solid polymer electrolyte membrane 115 is low, it can be said that the solid polymer electrolyte membrane 115 is generally a membrane that hardly causes crossover when incorporated in a fuel cell. Therefore, it can be estimated that the polymer electrolyte membrane 115 has good crossover characteristics.
Furthermore, in addition to the ratio of the amount of methanol at a specific location of the solid polymer electrolyte membrane 115, the crossover characteristics of the solid polymer electrolyte membrane 115 can be evaluated more accurately by grasping the self-diffusion coefficient of methanol at the specific location. be able to.

Next, the effect of this embodiment is demonstrated.
In the present embodiment, an oscillating magnetic field for excitation is applied to a specific portion of the solid polymer electrolyte membrane 115, a nuclear magnetic resonance signal generated in the solid polymer electrolyte membrane 115 is acquired, a methanol amount ratio is measured, To understand the transmission characteristics.
Therefore, when measuring the methanol permeation characteristics in a solid polymer electrolyte membrane as in the past, the catalyst particle diameter, catalyst pore diameter, catalyst coating density, diffusion coefficient of methanol and oxygen in the catalyst layer, methanol and oxygen Many factors such as mass transfer rate to the catalyst are not affected. Therefore, the measuring device 1 can obtain highly reliable methanol transmission characteristics.

Moreover, the performance of two different types of solid polymer electrolyte membranes using the conventional method of measuring the generated current of the entire cell of the fuel cell and the method of measuring methanol and carbon dioxide leaking from the air electrode side ( When attempting to evaluate methanol crossover characteristics) and methanol permeation characteristics, when measuring two different types of solid polymer electrolyte membranes, catalyst performance, catalyst coating density, and diffusion of methanol and oxygen in the catalyst layer A very large number of factors including the coefficient, the mass transfer rate of methanol and oxygen to the catalyst, etc. must be made exactly the same.
Therefore, it was very difficult to evaluate the methanol permeation characteristics of different membranes, and also the membrane performance, using conventional measurement methods.
On the other hand, as described above, the permeation characteristics of methanol obtained by the measuring apparatus 1 of the present embodiment are not affected by many factors as in the prior art. Therefore, the permeation characteristics of methanol and the solid polymer electrolyte membrane 115 The performance can be easily evaluated.

Furthermore, in the present embodiment, the ratio of methanol at a specific location of the solid polymer electrolyte membrane 115 is measured based on a chemical shift value spectrum (only the spectrum of hydrogen nuclei bonded to C atoms) indicating only methanol to be measured. is doing.
Even if the solid polymer electrolyte membrane 115 contains two types of protic solvents, methanol and water, a spectrum showing only methanol can be obtained based on the chemical shift value. As a result, even if the solid polymer electrolyte membrane 115 contains two types of protic solvents, methanol and water, the ratio can be calculated by distinguishing between methanol and water, and the solid polymer electrolyte can be calculated. The ratio of the amount of methanol in the film 115 and the ratio of the amount of water can be accurately measured.
Here, a solid polymer that covers the solid polymer electrolyte membrane 115 when measuring the methanol permeation characteristics at a specific location of the solid polymer electrolyte membrane 115 based on the spectrum of the chemical shift value indicating only methanol. It is also conceivable to use a larger RF coil than the electrolyte membrane.
The difference in frequency between the spectrum indicating the hydrogen nucleus bonded to the C atom and the spectrum indicating the hydrogen atom bonded to the O atom is about 1.5 ppm, which is very small.
Therefore, in order to separate and acquire the spectrum indicating the hydrogen nucleus bonded to the C atom and the spectrum indicating the hydrogen atom bonded to the O atom, the uniformity of the static magnetic field in the measurement region of the RF coil is very high. It is necessary to increase the level (for example, the nonuniformity of the static magnetic field needs to be 0.1 ppm or less).
However, when a large RF coil is used, the measurement area of the RF coil becomes large. That is, the area where the static magnetic field must be uniform becomes wide. For this reason, there are significant restrictions on the method of generating a static magnetic field in the static magnetic field application unit and the selection of the shape of the magnet in the static magnetic field application unit.
On the other hand, in this embodiment, since the small RF coil 114 smaller than the solid polymer electrolyte membrane 115 is used, the measurement region is small, and the region where the static magnetic field must be made uniform can be narrowed. Thereby, options, such as the generation method of the static magnetic field in a static magnetic field application part and the shape of the magnet 113 of a static magnetic field application part, can be expanded.

The solid polymer electrolyte membrane 115 contains two types of protic solvents, methanol and water. In the present embodiment, since the molar fraction, which is the ratio of methanol, is calculated as the methanol permeation characteristic at a specific location of the solid polymer electrolyte membrane 115, the molar fraction of water can also be grasped simultaneously.
Since the solid polymer electrolyte membrane 115 is required to suppress the permeation of methanol while maintaining good water permeation, the solid polymer electrolyte membrane can be obtained by grasping the molar fraction of methanol and water. 115 performance can be accurately grasped.

In the measurement mode for measuring the methanol ratio (permeation characteristics), the small RF coil 114 smaller than the solid polymer electrolyte membrane 115 is used to limit the portion to be measured. Can be measured.
In addition to this, in the present embodiment, the small RF coil 114 smaller than the first G coil 151A, the second G coil 151B, and the solid polymer electrolyte membrane 115 is used even in the measurement mode for measuring the self-diffusion coefficient. The site | part used as a measuring object is limited and the self-diffusion coefficient of methanol in a specific location can be measured.
By measuring not only the ratio of methanol at the specific location but also the self-diffusion coefficient at the specific location, the local behavior of methanol in the solid polymer electrolyte membrane 115 can be grasped more accurately.

  Furthermore, in this embodiment, the time for measuring the methanol permeation characteristic can be several hundreds of milliseconds, and the methanol permeation characteristic can be measured in a short time. By using the small RF coil 114, methanol permeation characteristics can be achieved in a short time.

In the present embodiment, an excitation oscillating magnetic field is applied to the solid polymer electrolyte membrane 115 by the small RF coil 114, and a nuclear magnetic resonance signal generated at a specific location in the solid polymer electrolyte membrane 115 is acquired. . Based on the nuclear magnetic resonance signal, the ratio of methanol at a specific location of the solid polymer electrolyte membrane 115 is calculated, and the methanol permeation characteristics of the solid polymer electrolyte membrane 115 are grasped.
Therefore, when grasping the methanol permeability of the solid polymer electrolyte membrane 115, it is not necessary to incorporate the solid polymer electrolyte membrane 115 into the fuel cell, and the methanol permeability of the solid polymer electrolyte membrane 115 can be easily obtained. I can grasp it.
Accordingly, the methanol permeation characteristics of the solid polymer electrolyte membrane 115 can be grasped in advance before the solid polymer electrolyte membrane 115 is incorporated into the fuel cell. As a result, the solid polymer electrolyte membrane 115 having desired methanol permeability can be selected in advance and then incorporated into the fuel cell.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS.
Although the measurement apparatus 1 includes one small RF coil 114, the measurement apparatus 6 according to the present embodiment includes a plurality of small RF coils 114 and a plurality of G coils 651 as illustrated in FIG. In the present embodiment, a gradient magnetic field application unit includes a plurality of G coils 651.
The G coil 651 used in the present embodiment is a planar coil, and the planar shape is a rectangular frame shape.
Such a G coil 651 and the small RF coil 114 are arranged in an array on the same plane. Specifically, the G coils 651 and the small RF coils 114 are alternately disposed, and the small RF coils 114 are disposed between the pair of G coils 651.
The plurality of small RF coils 114 and G coil 651 are fixed to a flat substrate 600.

As shown in FIG. 16, the transmission characteristic calculation unit 632 of the measurement device 6 includes a methanol ratio distribution in addition to the calculation unit 136 and the storage unit 137 including the data analysis unit 134 and the calculation unit 135 similar to those of the above embodiment. A calculation unit 638 is included.
The methanol ratio distribution calculation unit 638 calculates the distribution of the methanol ratio (in this embodiment, the molar fraction of methanol) calculated by the calculation unit 136.

Further, as shown in FIG. 17, the self-diffusion coefficient calculation unit 633B of the measurement apparatus 6 includes a self-diffusion coefficient estimation unit 133D, a correction unit 133F, and a correction parameter storage unit 133H that calculate the same self-diffusion coefficient as in the above embodiment. In addition, a self-diffusion coefficient distribution calculation unit 633I is provided.
The self-diffusion coefficient distribution calculation unit 633I calculates the distribution of the self-diffusion coefficient of methanol calculated by the correction unit 133F.
The measuring device 1 and the measuring device 6 are different in the number of small RF coils, the number of G coils, and the configurations of the transmission characteristic calculation unit and the self-diffusion coefficient calculation unit. It is the same.

According to such this embodiment, in addition to the same effect as the said embodiment, there exist the following effects.
In this embodiment, since a plurality of small RF coils 114 are provided, it is possible to apply an oscillating magnetic field for excitation to a plurality of specific locations of the solid polymer electrolyte membrane 115 and acquire an NMR signal corresponding thereto. It has become. Thereby, distribution of the ratio of the amount of methanol in the solid polymer electrolyte membrane 115 can be grasped.
For example, in the surface of the solid polymer electrolyte membrane 115, the substrate 600 is arranged so that the plurality of small RF coils 114 are arranged from the vicinity of the air supply port to the air electrode side of the fuel cell toward the air discharge port. It is possible to detect the crossover by grasping the ratio of the amount of methanol along the air flow.
And according to the state of each specific location, the supply_amount | feed_rate of methanol by the side of the fuel electrode of a fuel cell can be adjusted.
In addition, since the measuring apparatus 6 includes a plurality of G coils 651 in addition to the small RF coil 114, application of an excitation oscillating magnetic field and gradient magnetic field to a plurality of specific locations of the solid polymer electrolyte membrane 115 NMR signals corresponding to the above can be acquired. Thereby, the distribution of the self-diffusion coefficient of methanol in the solid polymer electrolyte membrane 115 can be grasped.

  Further, when the measuring device 6 is used for evaluating the performance of the solid polymer electrolyte membrane 115, the solid polymer electrolyte membrane is based on the distribution of the methanol ratio in the solid polymer electrolyte membrane 115 and the distribution of the self-diffusion coefficient. The performance of 115 can be comprehensively evaluated.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the above embodiments, the ratio of methanol and the self-diffusion coefficient of methanol at a specific location of the solid polymer electrolyte membrane 115 are measured, but the present invention is not limited to this. It is not necessary to measure the self-diffusion coefficient of methanol. In this case, since the G coil and the self-diffusion coefficient calculation unit are not required, the configuration of the measuring apparatus can be simplified.

Furthermore, in each said embodiment, although the ratio of methanol amount (ratio of the amount of methanol with respect to the sum total of the quantity of methanol and the quantity of water) was computed as the permeation | transmission characteristic of methanol in the specific location of the solid polymer electrolyte membrane 115, As a characteristic, the amount of methanol (absolute amount) may be calculated.
In this case, as shown in FIG. 18, the calculation unit 736 of the transmission characteristic calculation unit 732 includes a data analysis unit 134 and a calculation unit 735 that are the same as those of the above embodiments.

Further, it is assumed that the transmission characteristic calculation unit 732 includes a storage unit 737 that stores the correlation between the intensity of the spectrum indicating only methanol and the amount of methanol.
The data analysis unit 134 of the calculation unit 736 performs Fourier analysis on the nuclear magnetic resonance signal acquired by the small RF coil 114. Then, the calculation unit 735 acquires a spectrum of a chemical shift value indicating only methanol, and based on the correlation stored in the storage unit 737 and the acquired intensity of the spectrum, the solid polymer electrolyte membrane 115. Calculate the amount of methanol at a specific location.

Moreover, it is good also as a measuring apparatus which can measure both the ratio of methanol and the amount of methanol. That is, the transmission characteristic calculation unit may include the data analysis unit 134, the calculation unit 736, the calculation unit 136, the storage unit 137, and the storage unit 737.
In this case, the ratio of water and the amount of water can also be grasped by calculating the ratio of methanol and the amount of methanol.
As described above, in the solid polymer electrolyte membrane used in the fuel cell, it is necessary to increase the amount of water in the membrane, while reducing the amount of methanol in the solid polymer electrolyte membrane. By grasping the amount of water and methanol contained in the polymer electrolyte membrane, the performance of the polymer electrolyte membrane can be grasped more accurately and the evaluation of the polymer electrolyte membrane can be performed more accurately. Can do. In addition, the occurrence of crossover can be more reliably reduced by more accurately grasping the performance of the solid polymer electrolyte membrane.

Furthermore, the total amount of protic solvent (total amount of methanol and water) contained in the solid polymer electrolyte membrane is grasped, and the ratio of the amount of methanol is calculated as in the above embodiments.
Then, based on the ratio of methanol and the total amount of methanol and water, the absolute amount of methanol and further the absolute amount of water may be calculated.

In each of the above embodiments, the solid polymer electrolyte membrane 115 for a fuel cell is exemplified as a measurement target. However, the present invention is not limited to this.
Furthermore, in the said embodiment, although the specific location of the film | membrane containing two types of protic solvents, water and methanol, was measured, the protic solvent contained in a film | membrane is not restricted to water and methanol. For example, alcohol other than methanol may be included.
Further, three or more kinds of protic solvents may be contained in the membrane.
Furthermore, in the above embodiment, the ratio of the amount of methanol to the total protic solvent in the solid polymer electrolyte membrane 115 is calculated, but this is not limiting, and the ratio of one specific protic solvent contained in the membrane is one. The ratio of the amount of protic solvent may be calculated.

In each of the above embodiments, the solid polymer electrolyte membrane 115 includes methanol (CH ₃ OH) as a protic solvent and water (H ₂ O) as a protic solvent. Alternatively, CH ₃ OD as methanol and D ₂ O as water may be contained (D represents deuterium).
By doing so, it is possible to more reliably detect the spectrum of hydrogen nuclei of hydrogen bonded to C atoms when measuring transmission characteristics.
Moreover, when measuring the mobility of methanol, only the hydrogen nucleus couple | bonded with C atom of methanol can be excited reliably, and the mobility of methanol can be measured correctly.

Further, in the first embodiment, the static magnetic field H ₀ is perpendicular to the central axis of the support 201. However, as shown in FIG. 19, the static magnetic field H ₀ is in the same direction as the central axis of the support 201. A magnet (static magnetic field application unit) 413 may be arranged so as to be. In this case, it is necessary to exciting oscillating magnetic field H ₁ is applied to the central axis and vertical support 201, as shown in FIG. 20, the concatenation of the two spiral coil portions 414A, so-called " A small RF coil 414 of “eight-shape” or “butterfly type” is used. In other words, the small RF coil 414 has a plurality of spiral coil portions 414A arranged along a direction substantially orthogonal to the static magnetic field direction.
In such a configuration, the direction of the static magnetic field H _{0 and the} direction of the oscillating magnetic field H ₁ for excitation of the small RF coil 414 are orthogonal to each other, so that an NMR signal can be received.
Note that a spiral coil is used as the G coil 451. The G coil 451 is disposed so as to surround the small RF coil 414.

Next, examples of the present invention will be described. Here, the measurement device 1 of the first embodiment was used to measure the ratio (molar fraction) of methanol in the solid polymer electrolyte membrane.
First, the correlation between the ratio of the spectrum intensity indicating only methanol to the total value of the spectrum intensity of water and methanol and the ratio of methanol to the total amount of methanol and water was calculated.
Here, the ratio of the amount of methanol to the total amount of methanol and water is indicated by the mole fraction of methanol.

In order to calculate the correlation, NMR signals of the following three types of samples were acquired.
-Distilled water only-Methanol aqueous solution (mixed in a ratio of 44 mol% methanol and 56 mol% distilled water)
-Methanol only These solutions are each a container having the same shape as that of the solid polymer electrolyte membrane (the gap between two cover glasses (18 mm x 18 mm x 0.12 mm) arranged facing each other with a gap of 0.5 mm) The sample was put into a sealed container that can be held and sealed.
A small RF coil with an outer diameter of 2.0 mm and 3.5 turns is brought into contact with the cover glass, and a 90-degree excitation pulse is irradiated from the small RF coil, and an FID (free induction decay) signal (NMR) is generated by the small RF coil. Signal).

FIG. 21 shows the FID signal of distilled water. FIG. 22 shows the result of Fourier analysis of the FID signal of FIG.
The FID signal in FIG. 21 is acquired as a wave represented by a complex number by quadrature detection.
In FIG. 22, a coefficient obtained by performing a complex Fourier transform on the FID signal (a value obtained by squaring a Fourier coefficient of a real component and an imaginary component of the FID signal and taking a sum of squared values to obtain a square root) is plotted on the vertical axis. did. Further, the horizontal axis of FIG. 22 represents the unit of ppm in which the resonance frequency of the hydrogen nucleus bonded to the O atom is zero, and the “deviation” from this frequency is normalized at a magnetic field intensity of 43.1 MHz.

Next, FIG. 23 shows the FID signal of an aqueous methanol solution (a solution in which methanol and distilled water are mixed at a ratio of 44 mol% of methanol and 56 mol% of distilled water). FIG. 24 shows the result of Fourier analysis of the FID signal in FIG.
As shown in FIG. 23, beats were observed in the FID signal based on the difference in resonance frequency between hydrogen nuclei bonded to O atoms and hydrogen nuclei bonded to C atoms.
In FIG. 24, two spectra of a hydrogen nucleus bonded to an O atom and a hydrogen nucleus bonded to a C atom are seen.
The high frequency side is a spectrum due to hydrogen nuclei bonded to O atoms, and the low frequency side is a spectrum due to hydrogen nuclei bonded to C atoms. The difference in frequency between the two spectral peaks was about 1.5 ppm.
From this result, it can be seen that the spectra of hydrogen nuclei bonded to O atoms and hydrogen nuclei bonded to C atoms are clearly separated and measured.

Further, FIG. 25 shows the result of Fourier analysis of the FID signal of methanol.
Next, FIG. 26 shows the relationship between the molar fraction of methanol and the ratio of the spectrum intensity showing only methanol to the total value of the spectrum intensity of water and methanol.
FIG. 26 is created based on FIGS.
Here, the spectrum intensity is a spectrum area (a value obtained by integrating Fourier coefficients). Specifically, for example, it is a hatched portion in FIG. 24, and (area in a range from the top of the spectrum to ½ of the height of the spectrum) + (at a position of ½ of the height of the spectrum) Spectrum width × spectrum height dimension × 1/2 area).
As described above, the relationship between the molar fraction of methanol and the ratio of the spectrum intensity indicating methanol to the total value of the spectrum intensity of water and methanol can be obtained.

Next, using the following two solid polymer electrolyte membranes, NMR signals were obtained with a small RF coil, and the molar fraction of methanol was calculated.
・ Solid polymer electrolyte membrane that has been soaked in distilled water for 1 day and well wiped off the surface water (hereinafter referred to as solid polymer electrolyte membrane A)
-A solid polymer electrolyte membrane soaked in distilled water is thoroughly dried with hot air, immersed in methanol for one day, and the surface of methanol is thoroughly wiped off (hereinafter referred to as solid polymer electrolyte membrane B).

As the solid polymer electrolyte membrane, Flemion (trade name) manufactured by Asahi Glass Co., Ltd. was used. The dimensions of the solid polymer electrolyte membrane are 12 mm × 12 mm × thickness 0.5 mm.
The solid polymer electrolyte membrane immersed in the liquid was sandwiched between dry tissue papers, and the liquid on the surface of the solid polymer electrolyte membrane was well wiped off. This was sandwiched between two cover glasses (18 mm × 18 mm × 0.12 mm), and the periphery was sealed with a polyimide film and sealed.
Next, a small RF coil with an outer diameter of 2.0 mm and 3.5 turns is brought into contact with the cover glass, and a 90-degree excitation pulse is emitted from the small RF coil, and FID (free induction attenuation) is performed by the small RF coil. A signal (NMR signal) was acquired.

FIG. 27 shows the result of Fourier analysis of the FID signal of the solid polymer electrolyte membrane A. This spectrum has almost the same shape as that of distilled water in FIG. 22, and this solid polymer electrolyte membrane A is almost affected by the non-uniformity of the static magnetic field even in the water in the solid polymer membrane. However, it was found that spectra having almost the same half-value width can be obtained.
In addition, since the intensity of the spectrum indicating methanol (the spectrum of hydrogen nuclei bonded to C) is zero, referring to the graph of FIG. 26, the molar fraction of methanol at a specific location in the solid polymer electrolyte membrane A is It turns out that it is zero.

FIG. 28 shows the FID signal of the solid polymer electrolyte membrane B immersed in methanol. FIG. 29 shows the result of Fourier analysis of the FID signal shown in FIG. In FIG. 28, as in FIG. 23, a beat occurs in the FID signal due to the difference in the resonance frequency between the hydrogen nucleus bonded to the O atom and the hydrogen nucleus bonded to the C atom.
In addition, the spectrum shown in FIG. 29 has the same half-value width as that of the liquid methanol shown in FIG.
Furthermore, it was found from FIG. 29 that the ratio of the spectrum intensity indicating methanol to the total value of the spectrum intensity of water and methanol was 0.68.
Referring to the graph of FIG. 26, a numerical value of 0.68 indicates that the molar fraction of methanol at a specific location in the solid polymer electrolyte membrane B is 1.
Since the solid polymer electrolyte membrane is sufficiently dried in advance and then immersed in methanol, the solid polymer electrolyte membrane B is considered to be mostly occupied by methanol, and an appropriate molar fraction is measured. It can be said that it was possible.
Note that OH shown in FIGS. 22, 24, 25, 27, and 29 described above indicates a spectrum of hydrogen nuclei bonded to O atoms. In addition, CH shown in FIGS. 24, 25, and 29 indicates a spectrum of a hydrogen nucleus bonded to a C atom.

  In the said Example, although it measured about the ratio (molar fraction) of methanol in a solid polymer electrolyte membrane using the measuring apparatus 1 of 1st embodiment, using the measuring apparatus 6 of 2nd embodiment. Similar results can be obtained even when measurement is performed.

It is a schematic diagram which shows the state which installed the small RF coil in the position of Y = 0 of XZ plane. It is a figure which shows distribution of excitation of nuclear magnetization. It is a figure which shows the example of the PGSE sequence used in order to measure a self-diffusion coefficient. It is a flowchart which measures locally the mobility of the specific location of a solid polymer electrolyte membrane using PGSE method. It is a block diagram which shows the measuring apparatus concerning 1st embodiment. It is a figure which shows a small RF coil. It is a figure which shows an example of LC circuit. It is a circuit diagram which shows an example of a structure of a switch part. It is a schematic diagram which shows the G coil and small RF coil which were attached to the support body. It is a schematic diagram which shows the G coil attached to the support body, the small RF coil, and the solid polymer electrolyte membrane. It is a block diagram which shows the structural example of a control part. It is a block diagram which shows the structural example of a transmission characteristic calculating part. It is a block diagram which shows the structural example of a self-diffusion coefficient calculating part. It is a block diagram which shows the structural example of a self-diffusion coefficient calculation part. It is a figure which shows the small RF coil and G coil of the measuring apparatus concerning 2nd embodiment. It is a block diagram which shows the structural example of the transmission characteristic calculating part of the measuring apparatus concerning 2nd embodiment. It is a block diagram which shows the structural example of the self-diffusion coefficient calculation part of the measuring apparatus concerning 2nd embodiment. It is a block diagram which shows the structural example of the transmission characteristic calculating part concerning the modification of this invention. It is a schematic diagram which shows the modification of this invention. It is a schematic diagram which shows the small RF coil concerning the modification of this invention. It is a figure which shows the FID signal of distilled water in an Example. It is a figure which shows the result of having carried out the Fourier analysis of the FID signal of FIG. It is a figure which shows the FID signal of the methanol aqueous solution in an Example. It is a figure which shows the result of having carried out the Fourier analysis of the FID signal of FIG. It is a figure which shows the result of having Fourier-analyzed the FID signal of methanol. It is a figure which shows the relationship between the molar fraction of methanol, and the ratio of the intensity | strength of the spectrum which shows only methanol with respect to the total value of the intensity | strength of the spectrum of water and methanol. It is a figure which shows the result of having carried out the Fourier analysis of the FID signal of the solid polymer electrolyte membrane A. It is a figure which shows the FID signal of the solid polymer electrolyte membrane B. It is a figure which shows the result of having carried out the Fourier analysis of the FID signal shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 6 Measuring apparatus 102 RF oscillator 104 Modulator 106 RF amplifier 108 Pulse control part 110 Phase detector 112 Preamplifier 113 Magnet 114 Small RF coil 115 Solid polymer electrolyte membrane 116 Sample mounting stand 118 A / D converter 127 Sequence table 128 timer unit 129 operation signal receiving unit 130 arithmetic unit 131 data receiving unit 132 transmission characteristic calculating unit 133 self-diffusion coefficient calculating unit 133A data selection unit 133B self-diffusion coefficient calculating unit 133C parameter table 133D self-diffusion coefficient estimating unit 133H correction parameter storage unit 133F Correction unit 134 Data analysis unit 135 Calculation unit 136 Calculation unit 137 Storage unit 138 Output unit 151 G coil 151A First G coil 151B Second G coil 159 Current drive power supply 161 Switch unit 169B Control Unit 169 measurement mode switching control unit 169A measurement mode selection unit 171 gradient magnetic field control unit 201 support 201A protrusion 201B end surface 201C tip 413 magnet 414 small RF coil 414A coil unit 451 G coil 600 substrate 632 transmission characteristic calculation unit 633B self-diffusion Coefficient calculation unit 633I Self-diffusion coefficient distribution calculation unit 638 Methanol ratio distribution calculation unit 651 G coil 732 Transmission characteristic calculation unit 735 Calculation unit 736 Calculation unit 737 Storage unit A Solid polymer electrolyte membrane B Solid polymer electrolyte membrane

Claims (6)

A measuring device for measuring the permeation characteristics of at least one protic solvent at a specific location in a membrane containing two or more types of protic solvents,
A static magnetic field application unit that applies a static magnetic field to the film;
A small RF coil smaller than the film, which applies an oscillating magnetic field for excitation to the film and acquires a nuclear magnetic resonance signal generated at a specific location in the film;
Based on the nuclear magnetic resonance signal acquired by the small RF coil, a spectrum of a chemical shift value indicating only the one protic solvent is acquired, and based on the intensity of the spectrum, the specific location in the film A ratio of the amount of one protic solvent, and a permeation characteristic calculator that calculates at least one of the amount of the one protic solvent at a specific location in the membrane;
An output unit that outputs the value calculated by the transmission characteristic calculation unit as the transmission characteristic;
A measuring apparatus comprising: The measuring device according to claim 1,
The transmission characteristic calculator is
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum caused by each protic solvent contained in the membrane, and the amount of the one protic solvent relative to the total amount of the protic solvent Correlation with the ratio of
and,
A storage unit storing at least one of the correlation between the intensity of the spectrum indicating only the one protic solvent and the amount of the one protic solvent;
Based on the nuclear magnetic resonance signal acquired by the small RF coil, a spectrum resulting from each protic solvent at the specific location including a spectrum of a chemical shift value indicating only the one protic solvent is acquired,
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum due to each protic solvent at a specific location in the membrane,
and,
Calculating at least one of the intensities of the spectrum of the chemical shift value indicating only the one protic solvent,
Based on the correlation stored in the storage unit, the ratio of the one protic solvent amount to the total protic solvent amount at a specific location in the membrane, and the protic solvent at a specific location in the membrane A calculation unit for calculating at least one of the quantities;
A measuring apparatus comprising: The measuring apparatus according to claim 2,
The membrane contains water and alcohol as the protic solvent,
In the storage unit, there is a correlation between the ratio of the spectrum intensity indicating only the alcohol to the total value of the spectrum intensity caused by water and alcohol, and the ratio of the alcohol amount to the total amount of water and alcohol. Remembered,
The calculation unit of the transmission characteristic calculation unit calculates the ratio of the alcohol amount to the total amount of water and alcohol at a specific location in the membrane, and the water content with respect to the total amount of water and alcohol at the specific location in the membrane. A measuring apparatus characterized by calculating a ratio. In the measuring apparatus in any one of Claims 1 thru | or 3,
A plurality of the small RF coils;
The plurality of small RF coils apply an oscillating magnetic field for excitation to a plurality of specific portions of the film,
Obtaining a nuclear magnetic resonance signal corresponding to the oscillating magnetic field for excitation,
The measurement apparatus characterized in that the permeation characteristic calculation unit calculates at least one of the ratio of the one protic solvent amount and the one protic solvent amount at a plurality of specific locations of the membrane. In the measuring apparatus in any one of Claims 1 thru | or 4,
A gradient magnetic field application unit for applying a gradient magnetic field to the film;
A first measurement mode for measuring the permeation characteristics of at least the one protic solvent at a specific location in the membrane; and a first measurement mode for measuring the mobility of at least the one protic solvent at a specific location in the membrane. A measurement mode selector for selecting one of a plurality of measurement modes including two measurement modes;
A control unit that controls operations of the small RF coil and the gradient magnetic field application unit according to the measurement mode selected by the measurement mode selection unit;
A mobility calculator that calculates the mobility of the protic solvent at a specific location in the film based on the nuclear magnetic resonance signal acquired in the second measurement mode;
The controller is
When in the first measurement mode, an excitation oscillating magnetic field is applied to the specific part of the film by the small RF coil, and nuclear magnetic resonance is generated at the specific part corresponding to the excitation oscillating magnetic field. A signal is acquired by the small RF coil;
When in the second measurement mode, an oscillating magnetic field for excitation is applied to a specific portion of the film by the small RF coil, and a gradient magnetic field is applied by the gradient magnetic field application unit. A measuring apparatus configured to acquire a nuclear magnetic resonance signal generated by the small RF coil. A measurement method for measuring permeation characteristics of at least one protic solvent at a specific location in a membrane containing two or more types of protic solvents,
An excitation oscillating magnetic field is applied to a specific part of the film placed in a static magnetic field using a small RF coil smaller than the film, and a nuclear magnetic resonance signal generated at the specific part in the film is acquired. Process,
Based on the nuclear magnetic resonance signal acquired by the small RF coil, including a spectrum of a chemical shift value indicating only the one protic solvent, obtain a spectrum caused by each protic solvent in the specific location,
The ratio of the intensity of the spectrum of the chemical shift value indicating only the one protic solvent to the total value of the intensity of the spectrum caused by each protic solvent at a specific location in the membrane,
and,
Calculating at least one of the intensity of the spectrum of the chemical shift value indicating only the one protic solvent;
The ratio of the intensity of the spectrum showing only the one protic solvent to the total value of the intensity of the spectrum due to each protic solvent contained in the membrane, and the amount of the one protic solvent relative to the total amount of the protic solvent Correlation with the ratio of
Obtaining at least one of the correlation between the intensity of the spectrum indicating the one protic solvent and the amount of the one protic solvent;
Correlation with the value calculated in the step of calculating at least one of the ratio of the intensity of the chemical shift value spectrum indicating only the one protic solvent and the intensity of the chemical shift value spectrum indicating only the one protic solvent. Based on the correlation acquired in the step of acquiring a relationship, the ratio of the one protic solvent amount to the total protic solvent amount of the specific location in the membrane, and the specific location in the membrane Calculating at least one of the amount of one protic solvent;
Outputting the value calculated in the step of calculating as the transmission characteristic;
A measurement method comprising: