JPS6096502A - Process for producing hydrogen gas - Google Patents

Abstract

PURPOSE:To produce hydrogen safely and economically with a simple apparatus, by removing the oxide film from the surface of Al, forming Hg or amalgam coating layer to the surface, and contacting the Al with water thereby causing the decomposition of water. CONSTITUTION:The plate, chip, powder, etc. of Al is treated with an aqueous solution of a caustic alkali such as NaOH, KOH, etc. to remove the oxide film from the surface. A thin coating film of Hg or Zn amalgam having uniform thickness is applied to the treated surface e.g. by vacuum metallizing. When the metallized Al is immersed in water, water is decomposed into hydrogen and oxygen by the catalytic action of Hg or Hg in the amalgam. Generated hydrogen is collected in the form of gas, and oxygen reacts with Al to form Al2O3.

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a method for producing pure hydrogen gas inexpensively and safely using a simple device.

Conventional methods for producing hydrogen gas include water electrolysis,
There are methods for separating water and decoy gas, and methods for decomposing hydrocarbons, but these methods have the problem of requiring large-scale equipment. In addition, the electrolysis method of water is expensive due to the power consumption, while the separation method from water/gas and the decomposition method of hydrocarbons have carbon components mixed in the hydrogen gas, making it difficult to obtain pure hydrogen gas. There is a problem that.

In addition, as an experimental method for producing hydrogen gas, there is a method of immersing metallic sodium in water to generate hydrogen gas, but handling of metallic sodium etc. is dangerous and it is difficult to control the generation of hydrogen gas. There are safety issues. Moreover, N
AOH etc. are generated and become strongly alkaline, making it difficult to dispose of them.

The present invention solves all the problems of the above-mentioned conventional examples at once.A mercury or amalgam coating is formed on the surface of aluminum from which the oxide film has been removed, and then water is brought into contact with this to generate hydrogen gas. It is characterized by causing

To remove the oxide film of aluminum (including some other metals and impurities), caustic potash,
It may be cleaned with an alkaline liquid such as caustic soda or an acidic liquid such as hydrochloric acid or sulfuric acid. Specifically, aluminum plate,
The aluminum piece or aluminum powder may be immersed in a caustic potash solution, or the surface may be cleaned with the same. The oxide film removal method may be another method such as a mechanical method.

To form a mercury or amalgam film on the surface of aluminum from which the oxide film has been removed, mercury or amalgam, which has become a droplet due to surface tension, is placed on the aluminum surface, and this is formed into a thin film to cover the surface. good. The surface of aluminum from which the oxide film has been removed has good wettability with mercury (or amalgam), and the film is easily formed. Specifically, for example, an aluminum plate is immersed in a caustic potash solution,
After removing the oxide film, mercury or amalgam is applied to the surface of the aluminum plate to form a thin and uniform coating on the surface of the aluminum plate.

As a method for forming the film, other methods such as vacuum deposition of mercury or amalgam on the surface of an aluminum plate, aluminum piece, aluminum powder, etc. can also be adopted.

As the amalgam, cadmium amalgam, tin amalgam, silver amalgam, copper amalgam, etc. can be used, but the most preferable one is zinc amalgam. According to experiments, the rate of hydrogen gas generation is much better with zinc amalgam coatings than with mercury coatings.

When aluminum coated with mercury or amalgam is immersed in water as described above, the water is decomposed to generate hydrogen gas, and at the same time, the aluminum is oxidized to produce alumina. The aluminum may be brought into contact with water by immersing it in water or by spraying water vapor on it.

The hydrogen gas generation principle is as follows:
At the interface between aluminum (AI) and mercury (Hg), when AI is dissolved in Hg and amalgamated, the following reaction occurs as AI releases electrons.

Al-Al'' +3e- Next, the ionized AI and free electrons e- diffuse into the Hg of the coating, and the following reaction occurs at the surface in contact with water (H2O).

As a result, hydrogen gas and alumina are produced.

As the above reaction progresses, aluminum is consumed and changed to alumina, which is precipitated in water, while water is decomposed and hydrogen gas is generated. During this time, mercury acts as a catalyst and its amount does not increase or decrease. When amalgam is used as the coating, mercury in its components functions as described above, and other components such as zinc facilitate this function.

Further, the reaction is greatly influenced by water temperature, and the higher the water temperature, the higher the hydrogen gas generation rate. However, if the temperature is too high under atmospheric pressure, the reaction may become intense and the coating may peel off from the aluminum surface, so it is necessary to maintain the temperature at 90° C. or lower. It is preferable to keep the water temperature within the range of 40°C to 80°C.

According to the present invention, as described above, pure hydrogen gas can be produced using a very simple device. Furthermore, when calculating the energy consumption, it is possible to recover approximately 25% of the energy (power consumption) required to produce 99.99% pure aluminum, making it a more efficient power storage means than lead-acid batteries. Therefore, when using low-purity aluminum (99% purity), the energy consumed to generate hydrogen gas (the energy stored in aluminum) is less than the energy required for water electrolysis, etc., resulting in lower costs. Moreover, pure alumina, which is produced at the same time as hydrogen gas, is valuable as a raw material for new ceramics, and when the profits from this are taken into account, the cost of producing hydrogen gas can be significantly reduced. Furthermore, in the present invention, hydrogen gas production is accompanied by almost no danger, and the reaction product liquid is also neutral or weakly alkaline and can be easily disposed of, so it is also excellent in terms of safety.

(First example) 5 c+a X aluminum plates with a purity of 99.99%
'l c+nXo, 3 cn+' is cut into a rectangular plate-shaped aluminum piece and immersed in a caustic potash solution (20%) to remove the oxide film. Next, a thin film of mercury (approximately 50μ to 1OOμ thick) is formed on both surfaces of the aluminum piece (20.ffl in total) in a caustic potash solution. ).Then, the hydrogen gas generated in the device is counted.

FIG. 1 shows the cumulative amount of hydrogen gas generated as a result of the above.

A is when the water temperature is kept at 27℃, and the average water temperature is 19 per hour.
．． 5 cc of hydrogen gas was flushed.

B is when the water temperature is kept at 50℃, and the average of 11 per hour
4 cc of hydrogen gas was obtained.

C is when the water temperature is kept at 70℃, and the average is 34 per hour.
5 cc of hydrogen gas was obtained.

(Second Example) The same procedure as in the first example was carried out except that a zinc amalgam having a zinc content of about 5% or less was used as the coating. Set the water temperature to 50℃ and 7
Hydrogen gas generation rate (c
c/h) is shown in FIG. When the water temperature is maintained at 50° C., as shown by D, the peak is reached about 10 minutes after the start of the experiment and becomes about 7.000 cc/h. On the other hand, set the water temperature to 70
When the temperature is maintained at ℃, the peak value is reached about 3 minutes after the start of the experiment and becomes about 18,000 cc/h, as shown by E.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the amount of hydrogen gas generated and time when hydrogen is used as a coating, and Figure 2 is a graph showing the relationship between hydrogen gas generation rate and time when zinc amalgam is used as a coating. This is a graph showing. Agent Patent Attorney Masaru Ishihara

Claims (1)

[Claims] +11 A hydrogen gas production method characterized by forming a mercury or amalgam film on the surface of aluminum from which an oxide film has been removed, and then bringing water into contact with the film to generate hydrogen gas.