JP2014089862A - Electrolyte membrane for fuel cell and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method of utilizing an egg shell membrane.SOLUTION: The electrolyte membrane for a fuel cell is composed of an egg shell membrane 1. It is preferable that a compound having a coloring agent and a sulfonate group is adsorbed to the egg shell membrane 1. Red No. 106, Yellow No. 4, or Green No. 3 is preferable for a coloring agent, and polystyrene sulfonate is preferable for a compound having a sulfonate group. Also, it is preferable that both surfaces of the egg shell membrane 1 are coated with a metallic material, specifically platinum 2.

Description

  The present invention relates to an electrolyte membrane for a fuel cell comprising an eggshell membrane, and a fuel cell.

  In recent food culture, cooking using eggs has become indispensable. Especially in Japan, egg consumption per capita has been No. 1 in the world (320 / person 2009) since the latter half of the 20th century. For this reason, research and development has been conducted for a long time on the recycling of eggshells and the like produced in large quantities.

  However, most of the conventional methods of utilizing eggshells have focused on inorganic components and amino acids themselves, such as soil improvers and seasonings, and the structure of eggshell membranes that are the endothelium of eggs. There were few research examples that attracted attention.

  Therefore, the inventor of the present application has proposed a new usage method of eggshell membranes, specifically, a usage method as a photochromic molecule carrier in the following patent application. This invention mainly focuses on the adsorptivity of eggshell membranes.

Japanese Patent Application No. 2011-96831

  On the other hand, fuel cells are known as clean energy that does not use fossil fuels. Since this fuel cell can directly convert the energy of the fuel compound into electricity, it has attracted attention as a power generation means with little energy loss.

  There are several types of fuel cells, but direct methanol fuel cells belonging to polymer electrolyte fuel cells produce electrical energy starting from a chemical reaction between methanol and water. This direct methanol fuel cell, unlike a fuel cell using hydrogen as a fuel cell, can generate power using liquid fuel that is extremely easy to store and transport, so it can be used as a small and simple power source for automobiles and electrification. Application to products is expected. A direct methanol fuel cell or the like has a cell structure in which a catalyst layer and a gas diffusion layer (a conductive plate called a bipolar plate) are provided on both sides of a polymer electrolyte membrane.

  In addition, there is a polymer electrolyte membrane as a component that is indispensable in a fuel cell but has not been improved in satisfactory performance at present. Although it is known that the efficiency of proton transfer in this membrane is a factor that increases the power generation, there have been few proposals for effective new materials.

  The present invention has been made in consideration of the above-described matters, and an object of the present invention is to propose a new method of using an eggshell membrane, that is, a method of using it as an electrolyte membrane for a fuel cell.

  In order to solve the above problems, an electrolyte membrane for a fuel cell made of an eggshell membrane was used.

  This electrolyte membrane for fuel cells can provide a new use for eggshell membranes, and a new material can be proposed as an electrolyte membrane for fuel cells.

  The inventor of the present application pays attention to the fact that the eggshell membrane is a protein having a network structure composed of fine and strong fibers, and has conducted intensive research in order to use it as a new functional material. And this time, it discovered that eggshell membrane was suitable for the electrolyte membrane for fuel cells.

  The eggshell membrane may be an electrolyte membrane for a fuel cell in which a dye is adsorbed. At this time, it is preferable to use an electrolyte membrane for a fuel cell in which the dye is a water-soluble organic dye. Moreover, it is preferable to make it the electrolyte membrane for fuel cells whose pigment | dye is yellow No. 4, red No. 106, or green No. 3.

  When a pigment is adsorbed on an eggshell membrane, the electromotive force tends to increase when used as an electrolyte membrane of a fuel cell. This tendency is remarkable when yellow No. 4, red No. 106, or green No. 3 is adsorbed, and particularly when yellow No. 4 is adsorbed.

  It is also preferable to use an electrolyte membrane for a fuel cell in which a compound having a sulfonic acid group is adsorbed on the eggshell membrane. At this time, the compound having a sulfonic acid group is preferably polystyrene sulfonic acid.

  When a compound having a sulfonic acid group is adsorbed on the eggshell membrane, the electromotive force increases when used as an electrolyte membrane of a fuel cell. For example, when polystyrene sulfonic acid is adsorbed, the electromotive force is increased by 5 times or more.

  These electrolyte membranes for fuel cells can also be used as electrolyte membranes for polymer electrolyte fuel cells. Especially, it is preferable to use as an electrolyte membrane for direct methanol fuel cells.

  The eggshell membrane is obtained by taking out the contents from the egg to obtain an eggshell with an eggshell membrane, and immersing the eggshell with an eggshell membrane in an acetic acid aqueous solution to dissolve calcium carbide, which is the main component of the eggshell, It can also be used as an electrolyte membrane for a fuel cell.

  The electrolyte membrane for a fuel cell can increase the electromotive force of the fuel cell by immersion treatment in an acetic acid aqueous solution.

  Further, the above problem can be solved by a fuel cell using any one of the above electrolyte membranes. At this time, if a catalyst such as gold or platinum is coated on both sides of the eggshell membrane, the electromotive force increases. Especially, it is preferable from the surface of electromotive force to coat platinum on both surfaces of eggshell membrane.

  According to the present invention, a new utilization method of eggshell membranes can be proposed.

It is a photograph of eggshell membranes coated with platinum. It is a photograph which shows a mode that the eggshell membrane coated with platinum is introduced into a fuel cell kit. It is a graph which shows the IV characteristic of the fuel cell using the eggshell membrane which made polystyrene sulfonate adsorb | suck.

Hereinafter, an electrolyte membrane for a fuel cell and a fuel cell will be described by way of example. The electrolyte membrane for a fuel cell is made of an eggshell membrane. The fuel cell uses an electrolyte membrane made of eggshell membrane.
First, the eggshell membrane will be described.

[Egg shell membrane]
An eggshell membrane is a membrane that exists inside the eggshell of a bird or reptile egg. Bird eggs include chicken, duck, quail, emu, ostrich, duck and other eggs. Among them, it is preferable to use chicken eggshell membranes that consume a large amount. The main component of the eggshell membrane is insoluble protein (amino acid) rich in glutamic acid and cysteine.
In the present invention, eggshell membranes are used as electrolyte membranes for fuel cells. Since the amino acid side chain that forms hydrogen bonds inside the protein has a function of transferring protons, the eggshell membrane has a function as an electrolyte membrane for a fuel cell. The eggshell membrane can be used, for example, as an electrolyte membrane of a fuel cell using hydrogen as a fuel or a direct methanol fuel cell.

  The method for obtaining the eggshell membrane by separating it from the egg is not particularly limited. However, considering use as an electrolyte membrane for a fuel cell, a membrane having a certain area or more is required. Therefore, it is necessary to have a method of cutting a eggshell membrane that is as large and flat as possible from a spherical egg. For this purpose, for example, the following method can be used.

  First, after making a small hole (about 1 to 3 cm in diameter) at the sharp end of the egg and taking out the contents (yellow and white), the inside is washed with water. Next, the eggshell with an eggshell membrane that has been washed with water is immersed in an acetic acid aqueous solution to dissolve calcium carbide, which is the main component of the eggshell. At this time, for example, the calcium carbide can be dissolved by soaking in an 80-90% acetic acid aqueous solution for about 2 days. Finally, by thoroughly washing with water and removing impurities, an eggshell membrane that retains its original shape can be obtained. In order to cut out the eggshell membrane thus obtained into a sheet, for example, the following method can be used.

  The obtained eggshell membrane (usually holding almost the original shape of the egg) is cut into a substantially cylindrical shape with a central portion swelled by cutting off sharp and blunt ends using cutting means such as scissors. To do. Next, the substantially cylindrical eggshell membrane is cut in a direction that longitudinally cuts the sharp end portion and the blunt end portion and developed into a substantially sheet shape, and is cut out to a desired size (a size larger than the size of the electrode of the fuel cell). . The cut eggshell membrane may be dried (sun-dried or dried with a dryer or the like) with the four corners fixed with weights or the like.

  The eggshell membrane thus obtained is preferably adsorbed with a pigment. This increases the electromotive force of the fuel cell. Improvement of power generation performance can be realized simply by adding a highly corrosive and highly safe pigment. The dyes to be adsorbed are preferably Blue No. 2, Green No. 3, Yellow No. 4, Yellow No. 5, Red No. 3, and Red No. 106. Among these, yellow No. 4, red No. 106, or green No. 3 is particularly preferable. These dyes have a nitrogen-containing functional group capable of hydrogen bonding. Of these, yellow No. 4 is most preferable.

  In order to adsorb the pigment to the eggshell membrane, for example, the pigment is dissolved or dispersed in an aqueous solvent, and this aqueous pigment solution is applied to the eggshell membrane. The application method is not particularly limited as long as it can be applied to the eggshell membrane. Specifically, dip coating method, flow coating method, solution dropping method (including spray method), spin coating method, bar coating method, curtain coating method, die coating method, gravure coating method, roll coating method, blade coating method and A coating method such as an air knife coating method can be used. After coating, the water solvent contained in the aqueous dye solution is evaporated. Thereby, it becomes the structure which the pigment | dye adsorb | sucked to the eggshell membrane. Specifically, the pigment is incorporated into the lattice structure or network structure formed by the fine fibers of the eggshell membrane.

  On the other hand, it is also preferable to adsorb a compound having a sulfonic acid group to the eggshell membrane. This increases the electromotive force of the fuel cell. Among these, it is particularly preferable to adsorb polystyrene sulfonic acid.

  In order to adsorb polystyrene sulfonic acid, for example, the eggshell membrane may be immersed in an aqueous polystyrene sulfonic acid solution for several days, washed with water, and then dried.

  The eggshell membrane thus obtained can be used as an electrolyte membrane for a fuel cell. Hereinafter, a fuel cell using an electrolyte membrane made of eggshell membrane will be described as an example.

[Fuel cell]
In order to use the eggshell membrane obtained by the above method as an electrolyte membrane for a fuel cell, a catalyst layer is coated on both sides of the eggshell membrane. Various materials such as gold and platinum can be used for the catalyst layer, and it is particularly preferable to use platinum. In addition, various methods can be used for coating the catalyst layer, but it is preferable to use sputter coating.

The eggshell membrane coated with the catalyst layer thus obtained is used for a fuel cell using hydrogen as a fuel or a direct methanol fuel cell by being sandwiched between conductive plates called bipolar plates. Can do. Especially, it is preferable to use it for direct methanol fuel cells.
Hereinafter, the contents of the present invention will be described more specifically with reference to examples.

(Experiment 1: Advantage of eggshell membrane)
This experiment clarifies the superiority of eggshell membranes as electrolyte membranes for fuel cells in comparison with other materials.

  After the contents were taken out and washed with water, the eggshell with eggshell membrane was immersed in an acetic acid aqueous solution (90%) for 2 days to dissolve calcium carbide, washed with water and dried, and then cut into a size of approximately 3 cm × 3 cm. Then, platinum was coated on both sides of the eggshell membrane. Specifically, both sides of the eggshell membrane were coated for 180 seconds using a sputtering device (MSP-1S magnetron sputtering device manufactured by Vacuum Device). During sputtering, the portions other than the coating portion were masked, and the platinum layer was coated in a generally square shape (approximately 1 cm × 1 cm) (see FIG. 1). Then, as shown in FIG. 2, the eggshell membrane 1 coated with a platinum layer is replaced with an electrolyte membrane (Nafion membrane) N of a commercially available fuel cell kit (MEGACHEM-made methanol fuel cell demonstration kit 357E). A 3% methanol solution was injected.

  As comparative examples, samples were prepared for those using crab shells instead of the eggshell membrane and those using paper (recycled PPC paper made by Daio Paper). For the crab shell, the snow crab shell was washed thoroughly with water, and then the three-layer structure was peeled off by hand, and the transparent endothelium portion having high chitin purity was taken out and shaped with scissors.

  The IV characteristic was measured for each fuel cell sample to determine the optimum operating point (W = I × V). The IV characteristics were measured by the two-terminal method and the four-terminal method using IVP0605 manufactured by Asahi Spectroscopy.

  We found that eggshell membranes, which are mainly composed of proteins, transfer protons more efficiently than polysaccharide-based crab shells and paper.

  Further, a fuel permeability experiment was conducted on the eggshell membrane of Example 1, the crab shell of Comparative Example 1, and the paper of Comparative Example 2. Specifically, three cylinders made of vinyl chloride were prepared and fixed so that the length direction was along the vertical direction. Each sample (egg shell membrane of Example 1, crab shell of Comparative Example 1, paper of Comparative Example 2) was fixed to the lower opening of the fixed vinyl chloride cylinder by epoxy bond. Methanol (3 to 100%) was poured from the upper opening to a height of 20 cm, and the tendency of liquid leakage was observed for 24 hours.

  As a result of the experiment, it was confirmed that the eggshell membrane of Example 1 did not permeate even with 100% methanol. The crab shell of Comparative Example 1 and the paper of Comparative Example 2 both permeated methanol. From this result, it was found that the electrolyte membrane made of eggshell membranes hardly permeate methanol, and thus it is difficult to cross-leak, resulting in a methanol fuel cell in which fuel loss and power generation performance are unlikely to occur.

(Experiment 2: Superiority of dye adsorption)
This experiment clarifies the superiority of adsorbing the pigment on the eggshell membrane.

A sample was prepared by adsorbing the pigment (food pigment) to the eggshell membrane used in Example 1. As the dye, Blue No. 2, Green No. 3, Yellow No. 4, Yellow No. 5, Red No. 3, and Red No. 106, which are water-soluble organic dyes, were used. Each dye was dissolved or dispersed in an aqueous solvent, and this dye aqueous solution was applied to the eggshell membrane and then dried.
When the electromotive force of each fuel cell sample was measured with a digital multimeter (A & D AD-5529), an increase in electromotive force was observed when any of the dyes was used. It is an interesting result in terms of material development that the improvement in power generation performance was achieved simply by adding a highly safe pigment that is not corrosive. In particular, the electromotive force increased is shown below (Examples 2 to 4).

When the eggshell membrane with adsorbed dye was applied as a membrane for a fuel cell, the performance was improved over the membrane without addition. Red 106, yellow 4, and green 3 were particularly effective, and yellow 4 was the highest in electromotive force.
It is thought that the introduced pigment adhered due to the interaction with the eggshell membrane and showed the effect of contributing to proton conduction in protein as an organic molecule. Red No. 106, Yellow No. 4 and Green No. 3 which have been particularly effective have a common feature in that they have a functional group containing nitrogen capable of hydrogen bonding in the molecule.

(Experiment 3: Superiority of polystyrene sulfonic acid)
This experiment clarifies the superiority of adsorbing polystyrene sulfonic acid on eggshell membranes.

  A sample was prepared by adsorbing polystyrene sulfonic acid to the eggshell membrane used in Example 1 (Example 5). Specifically, the eggshell membrane was immersed in an aqueous polystyrene sulfonic acid solution (concentration 20%) for 2 to 3 days, washed lightly with water, then coated with platinum in the same manner as in Example 1 to prepare a sample, and the electromotive force was measured. .

  A membrane immersed in polystyrene sulfonic acid having the property of increasing proton conductivity was prepared and performance evaluation was performed. As shown in FIG. 3, the eggshell with an electromotive force of over 200 mV and no treatment. Compared to the membrane, the electromotive force was about 5 times or more. The performance was found to last for at least 2 hours.

  In addition to the fact that the sulfonic acid group is strongly adsorbed (ion-bonded) to the protein by the interaction with the amide group in the protein and the side chain site of the basic amino acid, these phenomena are I think it was because it worked.

(Experiment 4: Advantage of immersion treatment in acetic acid solution)
This experiment reveals the superiority of eggshell membranes obtained by immersing eggshells with eggshell membranes in an acetic acid aqueous solution.

  For comparison with Example 1 (with acetic acid treatment) immersed in an acetic acid aqueous solution, as Example 6, an eggshell membrane with an eggshell membrane taken out without being immersed in an acetic acid aqueous solution was used. Then, platinum was coated and replaced with an electrolyte membrane of a commercially available fuel cell kit. A 3% methanol solution was injected into the membrane, and the electromotive force was measured with a digital multimeter.

  It was found that a fuel cell using an eggshell membrane with acetic acid treatment as an electrolyte membrane has a higher electromotive force than a fuel cell using an eggshell membrane without acetic acid treatment as an electrolyte membrane. This suggests that the internal structure of the protein component of eggshell membranes affected by acetic acid changes, and the effect appears as a difference in performance.

(Experiment 5: Superiority of platinum coating)
This experiment examines the relationship between the electromotive force and the metal material coated on the eggshell membrane.

  A fuel cell was prepared in the same manner as in Example 1 except that gold was used instead of platinum as the metal material for coating the eggshell membrane (Example 7), and the electromotive force was measured.

  The fuel cell coated with platinum has significantly higher electromotive force than the fuel cell coated with gold. From this result, it was found that the function of platinum is important for generating electricity from chemical decomposition of methanol using eggshell membranes. A sample without metal coating was also produced, but almost no electromotive force was generated.

  Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and claims attached to the application of the present application by those skilled in the art or the like. Various changes and modifications can be made without departing from the scope.

1 Eggshell membrane 2 Platinum

Claims (10)

An electrolyte membrane for a fuel cell comprising an eggshell membrane.
Pigment is adsorbed to the eggshell membrane,
The electrolyte membrane for fuel cells according to claim 1.
The pigment is a water-soluble organic pigment,
The electrolyte membrane for fuel cells according to claim 2.
The pigment is Yellow No. 4, Red No. 106, or Green No. 3,
The electrolyte membrane for fuel cells according to claim 2 or 3.
A compound having a sulfonic acid group is adsorbed on the eggshell membrane,
The electrolyte membrane for fuel cells according to claim 1.
The compound having a sulfonic acid group is polystyrene sulfonic acid,
The electrolyte membrane for fuel cells according to claim 5.
The fuel cell
A direct methanol fuel cell,
The electrolyte membrane for fuel cells according to any one of claims 1 to 6.
Eggshell membrane
It is obtained by taking out the contents from the egg to make an eggshell with an eggshell membrane, and immersing this eggshell with an eggshell membrane in an acetic acid aqueous solution to dissolve calcium carbide, which is the main component of the eggshell,
The electrolyte membrane for fuel cells according to any one of claims 1 to 7.
A fuel cell using the electrolyte membrane according to claim 1.
Platinum is coated on both sides of the eggshell membrane,
The fuel cell according to claim 9.