JPS6152222B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hydrogen storage material made of a novel quaternary alloy. Specifically, the invention describes the formula
The present invention provides a hydrogen storage material made of a quaternary alloy having a composition of Ca _1-X La _X Ni _5-Y Al _Y (where X<1, Y<5). In recent years, thermal energy storage methods using metals, alloys, or their hydrides as hydrogen storage materials (for example, Shuichiro Ono, Chemistry Region, vol. 31, No. 1, pp. 39-47, 1977 ) was proposed. This heat storage method uses a metal, an alloy, or a hydride thereof that can undergo hydrogenation and dehydrogenation reactions reversibly, and stores heat and extracts energy through a reaction represented by the following formula. MH _{X →} M+H _X (endothermic reaction: heat storage process) M+H _X →MH This heat storage method is expected to be an innovative method for long-term heat storage, and intensive research is underway. Lanthanum-nickel alloy (LaNi ₅ ) manufactured by Philips of the Netherlands has been proposed as an alloy for use in the above heat storage method. This alloy is known to form solid hydrogen compounds with hydrogen, and hydrogen atoms can be bonded into the solid metal by contacting them with pressurized hydrogen, and the hydrogen bonded to the metal can be It can be released from the metal by raising and lowering the temperature. Furthermore, this metal is promising because it has a large hydrogen storage capacity and is easy to handle, but since it uses the rare earth element lanthanum, it is expensive, so the cost and drug properties are an obstacle to practical application. . Furthermore, nickel is also considerably more expensive than other elements, and there are no domestic resources for it. In addition, an alloy in which lanthanum was replaced with calcium was studied by the International Nickel Company (commonly known as Inco) in the United States, and a similar alloy in which nickel was replaced with aluminum was studied by Inco. has been considered by. The hydrogen storage material of the present invention takes the above alloy one step further and expands the alloy itself from a binary or ternary system to a quaternary system, and is more expensive and economical and is required as a hydrogen storage material. It satisfies the various conditions set forth below. A feature of the alloy of the present invention is that some of the metals constituting the known lanthanum-nickel alloy (LaNi ₅ ) are replaced with other metals.
Specifically, a formula in which lanthanum is partially replaced with calcium and nickel is partially replaced with aluminum.
A quaternary element having a composition represented by Ca _1-X La _X Ni _5-Y Al _Y (X < 1, Y < 5), where the value of It is a hydrogen storage material for alloys. The alloy of the present invention will be explained in detail below. The quaternary alloy of the present invention has a purity of 99%, with the nickel content and aluminum content being constant.
The above calcium powder, lanthanum chips, granular nickel, and aluminum chips were mixed according to the composition ratios shown in Table 1 (weighed as a total weight of 10 g), and alloyed by the known arc melt method in an argon gas atmosphere. The product was qualitatively analyzed by X-ray diffraction to determine the presence or absence of alloying, and the resulting alloy was dissolved in an inorganic acid and quantitatively analyzed by atomic absorption spectrometry to confirm that its composition was the same as the mixed composition. I confirmed that there is.

[Table] Furthermore, the hydrogenation characteristics (hydrogen dissociation pressure and hydrogen absorption amount) at 25°C were measured using the conventional method for the six types of alloys shown in Table 1.
The hydrogenation characteristics of LaNi ₅ and CaNi ₅ are also shown in FIG. 1 (a graph of hydrogen gas pressure at 25° C. - ratio of the number of bonded hydrogen atoms to the total number of metal atoms). As is clear from FIG. 1, all of the alloys of the present invention have sufficient hydrogen storage capacity at 25°C. In addition, from the viewpoint of practical ease of handling, the dissociation pressure at 25°C is preferably 10 Kg/cm ² or less, so the hydrogen storage material of the present invention is composed of Ca _{1 - X La} It has been found that a quaternary alloy having a composition represented by (X<1, Y<1), in which the value of X is 0.5 or less in the range of 0.2 to 0.4, is particularly preferable. As described above, the hydrogen storage material of the present invention is a novel and inexpensive hydrogen storage material made of a quaternary alloy, and has the following satisfactory properties. That is,
It can combine with hydrogen to form solid compounds, especially when contacted with pressurized hydrogen, hydrogen atoms can be combined into solid metals, and this hydrogenation reaction can be carried out at room temperature. It has a large hydrogen storage capacity. Furthermore, the hydride can release bonded hydrogen by arbitrarily raising or lowering the temperature, and the hydrogen dissociation pressure at room temperature is 10 Kg/cm ² or less, making it easy to handle. Therefore, it is extremely useful as a hydrogen storage material. Next, a typical example of a heat storage device using the hydrogen storage material of the present invention will be given, and its operating method will be explained with reference to the drawings. That is, in FIG. 2, for example, a heat medium collecting solar heat is guided to the heat storage tank 5 by the heat medium transport pipe 3, and the metal constituting the hydrogen storage material 7 in the heat storage tank 5 is absorbed by the heat. Or heat the hydride of the alloy to dehydrogenate it. The generated hydrogen gas is sent to the hydrogen storage tank 1 through the hydrogen flow pipe 4 (however, the portion inside the heat storage tank is a mesh pipe) by opening the valve 2 and stored therein.
Next, when it is desired to utilize heat, the hydrogen gas is introduced into the heat storage tank 5 by opening the valve 2, and the hydrogen is mixed with the hydrogen storage material 7 in which the metal or alloy hydride is dehydrogenated and converted into metal or alloy during the heat exchange. The generated heat is collected by the heat medium in the heat medium transport pipe 3 and used for heating and cooling, hot water supply, etc.

[Brief explanation of the drawing]

FIG. 1 is a hydrogenation characteristic diagram (dissociation pressure characteristic diagram) of various alloys, and FIG. 2 is a functional explanatory diagram of a typical heat storage device using metals, alloys, or hydrides thereof as hydrogen storage materials. DESCRIPTION OF SYMBOLS 1...Hydrogen storage tank, 2...Opening/closing valve, 3...Heat medium distribution pipe, 4...Hydrogen gas distribution pipe, 5...Thermal storage tank, 6...Insulating material, and 7...Hydrogen storage material.

Claims (1)

[Claims] 1 Formula Ca _1-X La _X Ni _5-Y Al _Y (However, the value of Y is 0.2 ~
In the range of 0.4, the value of X is 0.5 or less)
A hydrogen storage material made of a quaternary alloy having a composition represented by: