JPS6131302A - Preparation of metal hydride - Google Patents

Abstract

PURPOSE:To prepare a metal hydride having high hydrogen storage density with a simple device by generating discharge between electrodes, in which at least one of the electrodes is made of a hydrogen storage metal, in a medium for contg. the hydride, and converting eliminated particles from the electrode by the generated hydrogen to a metal hydride. CONSTITUTION:A medium 2 contg. a hydrogen compd. such as kerosene is filled in a treating tank 1, and electrodes 3, 4 are installed therein; for example, an anode 4 is made of a hydrogen storage metal such as LaNi5, etc. When electric discharge is caused between the electrodes 3, 4, H2 separated from kerosene reacts with fine particles dissociated from the surface of the anode 4 and forms metal hydride, such as LaNi5H, LaNi5H6.7 on the surface of the anode. Formed metal hydride is eliminated from the surface of the electrode and an interstice by the continuously caused impact of the electric discharge and settled on the bottom of the treating tank 1. In this stage, the reaction at the electrode is prompted by supersonic wave generated by a supersonic wave oscillator 6, and pulverization of the metal hydride and elimination from the electrode surface are prompted simultaneously, and the reaction is continued smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a metal hydride used as a means for storing and transporting hydrogen.

[Conventional technology]

Hydrogen has attracted a lot of attention in recent years as a new secondary energy source because it does not generate any harmful substances even when burned, so there is no risk of environmental pollution, and it can be used in a wide range of fields.

However, since hydrogen gas is the lightest gas with a weight of about 90 g, it has the disadvantage of being bulky and having poor storage and transportation efficiency. Therefore, it is possible to cool it to a low temperature, liquefy it, store it, and transport it, but it is not economical because liquefaction requires a large amount of energy and cold storage equipment is also required. However, it is difficult to use liquefied hydrogen in general except for special purposes.

In order to solve the problems mentioned above, in recent years, a technology has been developed to efficiently store hydrogen by combining hydrogen with titanium, magnesium, and other metals or alloys to form metal hydrides. This reaction is a reversible reaction represented by the following formula.

M + H2-MH2+ Q (Here, M is a hydrogen-adsorbing metal and Q is heat.) The equilibrium of the above reaction is determined by the temperature and the pressure of hydrogen gas, and if we let the metal react with hydrogen at a constant temperature, then Even if hydrogen gas is continuously supplied, the hydrogen reacts with the metal to form a metal hydride, and the pressure in the reaction chamber hardly changes within a certain range.

The above pressure increases as the temperature increases, and its characteristics draw a unique curve depending on the metal. Therefore, it is possible to change the hydrogen content in a metal by changing the pressure or temperature; hydrogen can be stored by increasing the pressure above the equilibrium pressure, and conversely, hydrogen can be released from the metal by heating it slightly. Just do it.

Hydrogen storage using metal hydrides has the following advantages: the above reaction has good reversibility, hydrogen storage density is large, special containers such as high-pressure containers or cold containers are not required, and hydrogen can be stored safely for long periods of time. It has many advantages, such as being able to be used regardless of size. Furthermore, as is clear from the above equation, the hydrogen storage metal generates heat when reacting with hydrogen and absorbs heat when releasing hydrogen, so it can also be used as an N heat medium.

Hydrogen storage metals currently in practical use include lanthanum-nickel alloys, iron-titanium alloys, magnesium-nickel alloys, etc. When hydrogen is reacted with hydrogen to form metal hydrides, It is known that the density of hydrogen contained in the metal hydride is approximately 1000 times that of gaseous hydrogen, that is, equivalent to or more than 1 times that of liquid hydrogen. An alloy of minostal (a mixture of cerium group rare earths such as cerium and lanthanum) and nickel, manganese, cobalt, etc. can also be used as a hydrogen storage metal.

(Problems to be Solved by the Invention) Therefore, in the method of obtaining a metal hydride by sending hydrogen into a reaction chamber containing a hydrogen storage metal as described above and causing the above reaction, In order to increase the storage density, it is desirable to pulverize the hydrogen storage metal to be exposed to hydrogen in advance and increase its surface area as much as possible relative to its volume. Furthermore, in the above reaction, if one attempts to increase the hydrogen storage density by increasing the proportion of metal hydride in the hydrogen storage metal, it is necessary to increase the pressure in the reaction chamber. There was also the problem that the equipment was too large.

[Means for solving problems]

The present invention has been made in order to solve the above problems, and its purpose is to completely eliminate the need for pulverizing the hydrogen storage metal in advance and to eliminate the need for high-pressure equipment. The object of the present invention is to provide a method for producing a metal hydride with a high hydrogen storage density using a relatively simple device.

Therefore, the gist of the present invention is to install an electrode made of a hydrogen storage metal as at least one electrode in a medium containing a hydrogen compound, to generate an electric discharge between the electrodes,
The purpose is to recover hydrogen as a powdered metal hydride by reacting the hydrogen generated in the electrode portion when the medium is decomposed by the discharge with the electrode material powder generated by peeling off from the electrode by the discharge.

As the medium, an organic liquid such as kerosene, water, or an organic gas is used.

In some cases, ultrasonic vibrations may be applied to the electrode part or the discharge gap part in order to promote the reaction in the electrode part and also to facilitate the pulverization of the metal hydride produced by the reaction. .

[For production]

In the above method, the hydrogen compound is decomposed by electric discharge and generates hydrogen ions, while the surface of the electrode made of the hydrogen storage metal described in 1-1 is excited by the electric discharge and partially is exfoliated or separated into fine powder, and the separated hydrogen quickly combines with the hydrogen storage metal to form a metal hydride. The metal hydride produced by reacting with the fine powder formed on the electrode surface and in the gap as described above becomes powder and detaches from the electrode surface and in the gap due to discharge impact, etc., and at least a part of it remains in the air on the electrode surface. 1. The unreacted hydrogen storage metal is exposed and the reaction and discharge continue to produce fine powder. If the above-mentioned powder is collected, a finely powdered metal hydride in which hydrogen is accumulated at an extremely high density can be obtained.

〔Example〕

Hereinafter, specific embodiments of the method of the present invention will be described with reference to the drawings.

The drawing is an explanatory diagram showing an overview of an embodiment of an apparatus for carrying out the method according to the present invention.

In the figure, 1 is a processing tank, 2 is a processing solution filled in the processing tank l containing hydrogen compounds such as kerosene, and 3 is made of wear-resistant materials such as copper, graphite, copper/tungsten, and tin/tungsten. cathode, 4 is 1. An anode made of a hydrogen storage metal such as aNi5, 5 a power supply device that applies a pulsed discharge voltage between the cathode 3 and anode 4, 6 an ultrasonic oscillator, 7 a metal separated from the anode surface and precipitated. It is a hydride.

The above-mentioned LaNi- is used as the anode 4, and it is opposed to the anode 3 with a small gap maintained, and a power supply 5 is applied between the two electrodes with a no-load voltage of V-200V and a pulse width of, for example, TON=1.8. When a discharge voltage of t+ sec and a peak current value Ip=50 A is applied, a discharge occurs between both electrodes. With this discharge, the kerosene between the two electrodes is decomposed into H2, C2H2, C2H4, etc., and the above H2
reacts with the surface of the anode (LaNi5) 4 and the fine particles separated from the anode, forming metal hydride LaNi5 on the anode surface.
The metal hydride LaNi5N6 generated on the electrode surface is detached from the electrode surface and gap by continuous discharge of 4 tons for 1 hour, and precipitates at the bottom of the treated layer. .

The ultrasonic waves generated from the ultrasonic oscillator 6 apply vibrations to the kerosene 2, the anode 4, etc. to promote the reaction at the electrode part, and also to pulverize the metal hydride produced by the above reaction and its Facilitates detachment from the electrode surface. Therefore, unreacted LaNi5 is always exposed on the electrode surface and the above reaction continues smoothly.

As a result of the experiment, the LaN15N G obtained as above
and LaNi51+- particle size is about 2.0 to 5.0μ,
In this case, the number of particles in ld was approximately 7.6×10 2 ”, and it was found that extremely high hydrogen storage performance could be obtained.

Hydrogen storage metals that can be used as materials for the anode 4 include Mg2Ni, FeTi, Ti, in addition to the above LaNi5.
Mn, M.

81, Ti (or Zr) -Ni, Ti (or Zr) -Cu, RCo5 (R is La, Ce, S
m) Alloys such as Mg, Ti, Zr, Las Ce
, , Nb, etc., or a composite thereof can be used.

If these hydrogen storage metals are used as the cathode 3, there will be less impurities in the generated metal hydride 7 and it will also be generated from the cathode 3, so the generation efficiency will increase.

Furthermore, the atmosphere in which the discharge is performed is not limited to the above-mentioned kerosene, but may be any other organic liquid or skewered water as long as hydrogen is separated by the discharge. You may also have them do this.

〔Effect of the invention〕

Since the present invention is constructed as shown on paper, when the present invention method θ is used, there is no need for pulverization treatment of the hydrogen storage metal, no high-pressure equipment is required, and a relatively simple equipment is used. A method is provided for producing a metal water 41 compound having a high hydrogen storage density.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but includes all modified embodiments that can be easily conceived by a person skilled in the art from the above description within the scope of the purpose of the present invention. be.

[Brief explanation of the drawing]

The drawing is an explanatory diagram showing an overview of an embodiment of an apparatus for carrying out the method according to the present invention. j - Processing tank 2 - Processing liquid 3 containing hydrogen compounds
-Cathode 4-----Anode 5 made of hydrogen storage metal
− −Power supply device 6 − Ultrasonic oscillator

Claims (1)

[Claims] 1) In a medium containing a hydrogen compound, a discharge is generated between electrodes, at least one of which is made of a hydrogen storage metal, and the hydrogen generated in the electrode portion converts the particles detached from the electrode into metal hydride. A method for producing a metal hydride, characterized by changing the metal hydride. 2) The method for producing a metal hydride according to claim 1, wherein the medium is an organic liquid. 3) The method for producing a metal hydride according to claim 2, wherein the medium is kerosene. 4) The method for producing a metal hydride according to claim 1, wherein the medium is water. 5) The method for producing a metal hydride according to claim 1, wherein the medium is an organic gas. 6) The metal hydride manufacturing method according to any one of claims 1 to 5, wherein ultrasonic vibration is applied to the electrode portion.