JPS60135540A - Hydrogenatable alloy - Google Patents

Abstract

PURPOSE:To obtain the titled alloy absorbing a large amount of hydrogen, easy to activate, and having a high reaction rate by substituting misch metal having a reduced Ce content for part of Ca in a Ca-Ni alloy and a metal such as Al for part of Ni so as to provide a spceified composition. CONSTITUTION:This hydrogenatable alloy is represented by a formula Ca1-x (CFMm)xNi5-yMy (where CFMm is misch metal having <=10wt% Ce content, M is Al, Mn, Cu, Fe, Co or Ti, 0<x<1, and 0<y<5). The alloy is a superior hydrogen storing alloy absorbing a large amount of hydrogen, easy to activate in the early stage of a hydrogenation reaction, and having a high reaction rate. The hysteresis between the absorption and dissociation of hydrogen is small, and the equilibrium hydrogen pressure at ordinary temp. is within the range in which the alloy is easily handled. It is desirable that (y) is 0.1-1.2 in the formula when (x) is 0.1-0.9.

Description

[Detailed description of the invention] This invention relates to alloys that can be hydrogenated.

Various metals or alloys absorb a large amount of hydrogen and are hydrogenated to produce metal hydrides, and the produced metal hydrides can release hydrogen by controlling temperature, hydrogen pressure, etc. It is already known that the metal or alloy returns to its original form. Utilizing these properties, metal hydrides are expected to be used as hydrogen storage materials. In addition, hydrogen absorption
It is expected to be used as a heat storage material that utilizes the reaction heat generated during release.

(b) Prior art The conditions necessary for the use of metals or alloys that can be hydrogenated in the above manner are: ■ having an appropriate hydrogen dissociation pressure at room temperature, ■ having a high reaction rate with hydrogen gas under operating conditions, and ■ Examples include that activation at the initial stage of the hydrogenation reaction is easy, and (2) raw materials are available at low cost.

Conventional alloys that form metal hydrides include LaNi,
.

FeTi, M&Ni, MmNj4. OaN:14 is known as a typical example.

However, for conventional metal hydride-forming alloys,
Each has the following problems. IJaNi.

The raw materials for p and FeTi are expensive, and although p and FeTi are cheap, activation at the initial stage of the reaction is difficult. M&Nj- needs to be heated to 300° C. or higher to obtain a hydrogen dissociation pressure of 1 atm or higher, and its reaction rate with hydrogen is also slow. MmNi5 has a slightly high hydrogen dissociation pressure of about 23 atmospheres at room temperature.

CaNi-1 has the advantage that activation at the initial stage of the reaction is harmful and the reaction rate is fast, but it has problems such as a low hydrogen dissociation pressure of about 0-4 atm at room temperature.

(CF)vim)Ni, is Mitsushmetal, v (C!FMm), which contains 10% by weight or less of cerium, which is produced by reducing cerium, the main component of Mitsushmetal~Mm, which is a mixture of rare earth elements, in the oxide stage. The hydrogen dissociation pressure is lower than that of MmNi, but the hydrogen dissociation pressure is lower than that of I
It is expensive compared to ANi, and has problems such as difficulty in activation at the initial stage of the reaction, slow reaction rate, and large hysteresis between hydrogen absorption and dissociation.

As described above, the metal hydrides of conventionally known alloys each have their own problems and cannot necessarily be said to be practical as hydrogen storage alloys.

(c) Purpose of the Invention This invention was made to improve the above-mentioned problems, and the hydrogen absorption amount is large, the activation at the initial stage of the hydrogenation reaction is harmful, and the reaction rate is also large. The object of the present invention is to provide an alloy that is excellent as a hydrogen storage alloy, which has a small hysteresis between hydrogen absorption and dissociation and whose equilibrium hydrogen pressure at room temperature is within a manageable range IC.

[) Structure of the Invention This invention is based on the formula Cal-z(CFMm)
(In the formula (OFMm), the content of Seri A is 10% by weight.
The following Mitsushmeta ~, M is aluminum, manganese,
Copper, iron, cobalt or titanium, o<i-<b,,o
< y < 5] is provided.

A feature of the alloy of this invention is that a part of the metal constituting the calcium-nickel alloy (CaNis), which is a known hydridable alloy, is replaced with another metal. That is, part of the calcium is replaced with another metal. A quaternary alloy having a composition represented by -3= in the above formula, in which a portion of nickel is replaced with aluminum, manganese, copper, iron, cobalt, or hirodethane, with an amount of Mitsushmetal tv (CFlvlm) of 10% or less It is an alloy that can be hydrogenated.

The alloy suitable for this invention has a calcium metal of 0.1 to 0.9 atoms, that is, X in the formula is 0.1 to 0.
．． 9, on the other hand, the number of atoms of Futatsuke-metal is 3.8-4.9, that is, y is 0.1-1.20 alloy. Preferably, when x is in the range of 0.3 to 0.7, y is in the range of 0.2 to 1.
It is an alloy in the range of 0.

In the alloy of this invention, CFMm means mitushmetal y with a cerium content of 10% by weight or less, while mitushmetal μ is a mixture of rare earth elements, and its composition is described, for example, in "Rare Earth J" (ed. Kano, Yanagita, 1980). Examples include those with the following composition described in 2010, Gihodo Publishing).

Ce about 51% by weight IA 1132 ll Pr tt 4 n N (1tt12 n Other rare earth elements n 0.+5 nFe, Ca,
Si, Al, Mg It 0.5 u 4 - And the CFMm used in this invention is obtained by removing Ce from the above Mitsushmetal in the oxide stage.
It is produced by performing electrolysis. CFMm, which is Mitsushmetal used in this invention, has a cerium content of 1
The content is 0% by weight or less, and it is considered as t% mold, which does not contain any cerium, that is, the cerium content is 0%.
Includes 4 things.

The preferred range of cerium content is 0.1 to L0% by weight. Examples of the CFMm include those having the following composition.

La 60-70% by weight Cθ 0.1-10 1/ Pr 5-13 tt Nd 20-304 8m 0.1-1.0 // Other metal elements 0.5-1.5〃 Hydrogenation of this invention Uru alloy is made by weighing and mixing powders (usually 50 to 100 mesh) or acid chips of each raw material metal to obtain the desired composition, press-forming the mixture, and then melting it in an arc melting furnace.
It can be manufactured by melting using a high frequency vacuum induction melting furnace or the like.

(e) Examples Metals were weighed and mixed so that the compositions of the resulting alloys would be Examples 1 to 7 and Comparative Examples 1 to 2 in Table 1, and after press forming, they were melted in an arc furnace to produce alloys.

The metal raw materials CFMm are IA 64%, Ce
0.5%, PrlO%, Nd, 25%, Sm o-1s
% and other metals 1% (both weight %).

In addition, the product was qualitatively analyzed by X-ray diffraction to determine the presence or absence of alloying, and the resulting alloy was dissolved in inorganic acid and quantitatively analyzed by atomic absorption spectrometry to confirm that its composition was the same as the mixed composition. .

After pulverizing the obtained alloy to 100 meshes or less, 15
Deaeration at 0℃ and hydrogen pressurization (approximately 30 atm) at 25℃
The activation treatment was repeated ~3 times. The P-C-T properties of the activated alloys were measured using a conventional pressure-composition-temperature (P-C-T) measuring device. Measurement results first
In particular, the P-C-T characteristic diagrams for the alloys of Examples 1 and 6 and Comparative Examples 1 and 2 are shown in FIG.

Similar to Table 1: Equilibrium hydrogen dissociation pressure (atmospheric pressure) Pa: Equilibrium hydrogen absorption pressure (atmospheric pressure) (Both cases are when the number of absorbed hydrogen atoms per alloy 17 is 2.5) As shown in Table 1 It can be seen that the hydrides of Examples 1 to 7 of the present invention all have a large hydrogen absorption capacity, with an absorption number of hydrogen atoms of 4.6 to 5.4 at 10 atm and 25°C. In addition, the equilibrium hydrogen dissociation pressure at the number of absorbed hydrogen atoms of 2.5 per 17 parts of the hydride alloy in these examples is 0.5 to 1.5 atm, which is within the range that is easy to handle, and within the range of the above general formula. It can be seen that this equilibrium hydrogen pressure can be adjusted arbitrarily by changing the composition. Furthermore, the hysteresis between the time of hydrogen absorption and the time of dissociation is clear from the hysteresis factor shown in Table 1, in CaNi of Comparative Example 1.

The (CFlvlm) of Comparative Example 2 is as small as that of the alloy.
Much smaller than Ni.

Further, the alloys of the above embodiments of the present invention were subjected to the activation treatment described above, namely, degassing at 150°C and hydrogen pressurization at 25°C (approximately 3
0 atm) It was almost completely activated just by returning it to the t2-3 line, and activation at the initial stage of the reaction was easy. Furthermore, when measuring the P-C-T characteristics of these alloys of the present invention, the time taken to reach densification equilibrium was found to be 10 to 15 minutes.
The reaction rate is sufficiently fast.

(f) Effect 8- The hydrogenatable alloy of this invention has a high hydrogen absorption capacity,
Activation at the initial stage of the reaction is easy, the reaction rate is fast, the hysteresis between hydrogen absorption and dissociation is small, and the equilibrium hydrogen pressure is within an easy-to-handle range and can be changed arbitrarily, making it extremely superior in practical terms. It is a hydrogen storage alloy.

[Brief explanation of the drawing]

FIG. 1 is a P-C-T characteristic diagram at 25 DEG C. of the hydrides of the alloys of Examples 1 and 6 and Comparative Examples 1 and 2 of the present invention.

Claims (1)

[Claims] 1, Formula Cal-X(CFMIII)XNj4-7M7
(In the formula, (CFMm) has a cerium content of 10% by weight.
The following Mitsushmetal 1M is Aμ minicum, manganese,
JR1&, Koba