JPS5950744B2 - Alloy for hydrogen storage - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a hydrogen storage material, more specifically, a novel hydrogen storage material that can store a large amount of hydrogen in the form of a hydride, and can easily and quickly release hydrogen with slight heating. The present invention relates to a useful Ti-based ternary alloy for hydrogen storage.

Recently, hydrogen has attracted attention as a new energy alternative to fossil fuels because it has no resource constraints, is clean, can be transported and stored, does not disturb natural cycles, and has a wide range of uses. It's coming.

Traditionally, hydrogen has been stored as gaseous or liquid hydrogen or as a metal hydride, and recently storage methods as metal hydrides have attracted particular interest.

The properties required for a substance that stores hydrogen in the form of metal hydride include (1) the substance is inexpensive and abundant in terms of resources, and (2) it is easy to activate and can absorb hydrogen. (3) It has an appropriate dissociation equilibrium pressure near room temperature, (4) The hydrogen storage and release reactions are reversible and fast, and (5) It is light in weight. can give.

However, transition metals such as Ti and Zr, which have been known to generate hydrides, are very thermally stable in the form of hydrides and release hydrogen only at high temperatures of, for example, 400°C or higher. Its practicality as a hydrogen storage material is poor.

In addition, in recent years, alloys mainly containing Ti, such as Ti-Ni,
Ti-Co, Ti-Fe, etc. have been developed, but these are all thermally stable like the above-mentioned Ti, but they also require a long time to absorb and release hydrogen, making them difficult to use as metal raw materials. However, at the same time, the hydrogen to be stored is also limited to high purity, which is an unavoidable disadvantage as a hydrogen storage material.

As mentioned above, each of the hydrogen storage materials proposed in the past has drawbacks, and metals, alloys, etc. that have the above-mentioned properties required as hydrogen storage materials have not yet been developed.

In view of the above-mentioned current situation, the present inventor has made various efforts to obtain an alloy having various properties required as a hydrogen storage material.

As a result, Ti-based ternary alloys are obtained by replacing a predetermined amount of Ti in Ti-Ni alloys and Ti-C0 alloys with specific metals.
We have discovered that this alloy possesses all of the above-mentioned properties and is extremely useful as an alloy for hydrogen storage, unprecedented in the prior art, and have now completed the present invention.

That is, the present invention provides general formula Ti, A1. It is a hydrogen storage alloy represented by B, where A is AI, Cr, Cu.

Fe, Mg, Mn, Mo, Si, Zn or Zr, B is Ni or Co, n is 0.5-0
．． The number ranges from 95 to 95.

However, if B is CO and A is Fe, it is not included.

The Ti-based ternary alloy of the present invention is a novel alloy developed by the present inventor for the first time, and has all the properties required as a hydrogen storage material as described above.

In particular, it is inexpensive, can be easily activated, can store a large amount of hydrogen at a high density, and has the characteristics of being able to easily and quickly release the stored hydrogen by mild heating at or slightly above room temperature. .

Furthermore, the hydrogen storage capacity of the alloy of the present invention is not affected by the purity of the hydrogen to be stored, and therefore it is possible to store hydrogen that is relatively impure, that is, hydrogen that contains some amount of oxygen, nitrogen, argon, carbon dioxide, etc. in the gas. It can be stored efficiently.

In addition, the alloy of the present invention has the advantage that the performance of the alloy does not deteriorate even after repeated hydrogen storage-release operations, and it maintains its initial hydrogen storage capacity for a long period of time.

The above-mentioned various excellent features are especially important when A in the general formula [■] is Cr.
, is noticeable for alloys that are Mn or Zr.

Moreover, the larger n in the general formula [■], the more pronounced the effect becomes, and it is best that n is 0.8 to 0.95.

In producing the Ti-based ternary alloy represented by the above general formula [■] of the present invention, various known methods can be employed, but preferably an arc light melting method can be employed.

That is, Ti, component A, and component B are each press-molded into an arbitrary form in the form of a powder or an appropriate molded body (usually a rod-like shape) so that the composition of the alloy represented by the general formula [■] is obtained, and then the molding is performed. It can be easily obtained by charging the material into a known arc-light melting furnace, heating and melting it in an inert atmosphere, and allowing it to cool.

The thus obtained Ti-based ternary alloy of the present invention is advantageously used in the form of powder because its surface area can be increased.

Moreover, the above-mentioned alloy can be activated very easily, and after activation, it can easily and rapidly absorb and release a large amount of hydrogen.

Activation is carried out by performing the operation of occluding and desorbing hydrogen in the alloy once or twice depending on the type of alloy.

This hydrogen storage operation, that is, the hydride formation operation, involves filling the above-mentioned alloy powder into a suitable container, heating it to seal hydrogen in the system, applying a hydrogen pressure of about 50 kg/cm□, and allowing it to cool. This is done by

In particular, the alloy of the present invention has the advantage that this occlusion operation can be carried out at a low temperature of about 200° C. in an extremely short time of about several minutes.

On the other hand, the known Ti-Fe alloy is
When a hydrogen pressure of 0 kg/cm2 is applied, hydrogen storage does not substantially occur, and therefore activation is not possible.

The occlusion operation requires a high temperature of approximately 450 to 500°C, and activation requires repeating this occlusion operation several times.

Also, even in Ti-C0 and Ti-Ni alloys, the above 20
Under the conditions of 0°C and 50 kg/cm2, hydrogen storage is quite slow, and it takes tens of minutes to several hours to form a sufficient amount of hydride, and the above storage operation must be repeated several times to activate it. Must be repeated.

After the above storage operation is completed, the stored hydrogen is easily released by simply exhausting the system, thereby completing the activation of the alloy.

To store hydrogen in the thus activated alloy, the alloy is filled in a hermetically sealed container, such as a normal cylinder, and then stored at room temperature or higher, preferably at a temperature of about 30 to 150°C, at a rate of 10 kg/day. It is carried out by filling hydrogen gas at a pressure of about cm□ or higher and returning it to room temperature.
This allows the alloy to store a large amount of hydrogen in the form of hydrides within the alloy in a short period of time.

Further, hydrogen can be released from this hydride by simply opening the container and bringing it to normal pressure and room temperature, but in order to release hydrogen more efficiently and in a shorter time, it is usually
It is desirable to heat to a temperature of about 0° C., to reduce the pressure to a level corresponding to this temperature, or to combine both.

This operation of absorbing and desorbing hydrogen into the activated alloy of the present invention can be carried out at a very low temperature compared to conventionally known alloys such as Ti-Ni alloys. Ti-Ni
It has the advantage that it can be carried out efficiently at a speed two to three times higher than that of the previous method.

Furthermore, in the alloy of the present invention, since the hydrogen storage and release described above is completely reversible, no matter how many times the hydride formation and its decomposition reactions are repeated, there is virtually no deterioration of the alloy itself. It can be used for a long time.

As described above, the alloy of the present invention can store a large amount of hydrogen with easy operation, and can also release hydrogen easily and quickly, making it extremely useful as an alloy for hydrogen storage.

Examples will be given below to explain the present invention in more detail.

Example 1 Formula TinA1-nCo (wherein A is A 1 , Cr,
Cu, Fe.

Mg, Mn, Mo, Si, Zn, or Zr and n is a number from 0.5 to 0.95).
I, Co and A components each have a diameter of about 3 mm and a length of about 15 mm.
The mixture was mixed in the form of 0 mm rod-shaped pellets, and then the mixture was press-molded into cylindrical tablets.

This was charged into a copper crucible of a high-vacuum arc-light melting furnace equipped with a thorium tungsten electrode, and after creating a high-purity argon atmosphere in the furnace, it was heated to approximately 2000°C, melted, and allowed to cool, resulting in the results shown in Table 1. Ti-based ternary alloys with various compositions were obtained.

The obtained alloy was pulverized into 120 meshes, and 5.0 g thereof was collected into a stainless steel hydrogen storage and release reactor, and the alloy was activated as follows.

That is, the temperature of the exhaust liquid inside the reactor is maintained at 200°C, and the purity is 9.
Introducing 9.9999% hydrogen and increasing the hydrogen pressure inside the vessel to 50k
After maintaining the temperature at g/cm□, the system was cooled and returned to room temperature to complete the hydrogen storage operation, and was then evacuated again to complete the hydrogen release operation.

The alloy activated by performing the above storage-desorption cycle once or twice was then allowed to absorb 99.9999% pure hydrogen at 60 DEG C. and under a hydrogen pressure of 10 kg/cm@2 for hydrogen encapsulation storage.

Table 1 shows the hydrogen storage rate at this time and the composition of the present alloy (hydride) at 130° C. after hydrogen storage.

For comparison, Table 1 also shows similar hydrogen storage rates and compositions at 130°C for Ti--Co alloys produced and activated in the same manner as above.

From Table 1 above, the Ti-based ternary alloy of the present invention is TiC.

It can be seen that compared to (Sample A26), it can store the same or more hydrogen at 130° C., and the storage rate is actually more than twice as fast.

Further, the release of hydrogen from the hydride of the alloy of the present invention can be easily carried out by heating the reactor to room temperature or higher temperature, reducing the pressure, or a combination of the two, and the release rate is The absorption rate was also extremely fast, similar to the above-mentioned absorption rate.

Example 2 Following the procedure of Example 1, TinA, , Co (
A and n are the same as in Example 1) After manufacturing the alloy, it was activated using hydrogen with a purity of 99.5%.

That is, the hydrogen absorption and release cycle was repeated once or twice to complete the activation of the alloy.

The activated alloy is then exposed to a temperature above room temperature and 50 kg
Hydrogen with a purity of 99.5% was sealed and stored at a hydrogen pressure of /an□ or less.

The storage rate and storage amount (composition of the hydride) are almost the same as in Example 1, and the operation and release rate of hydrogen from the hydride thus obtained are also easy and as in Example 1. It was prompt.

Further, when the composition of the hydride of the alloy of the present invention was examined after 50 repetitions of occlusion and desorption of hydrogen with a purity of 99.5%, no change was observed in the composition shown in Table 1.

This shows that the alloy of the present invention is not affected by the purity of hydrogen;
Furthermore, it can be seen that no deterioration in performance is observed even after repeated occlusion and desorption.

Example 3 The formula TinA1-nN1 (wherein A is AI, Cr, Cu, Fe, Mg, Mn,
After manufacturing the Ti-based ternary alloy of the present invention represented by Mo, Zn and Zn are numbers from 0.5 to 0.95, these are crushed in the same way, activated, and hydrogenated. performed the occlusion.

Table 2 shows the produced alloy, its composition at 200° C. after hydrogen storage, and its storage rate at 60° C. and 10 kg/cm 2 .

Table 2 also includes Ti--Ni alloys for comparison.

As shown in Table 2 above, the formula TinA1. Ni (A
and n are the same as above), the alloy of the present invention is Ti-
It can be seen that it has a hydrogen storage capacity equal to or higher than that of the Ni alloy, and its storage rate is more than twice as high.

As in Example 1, hydrogen release from the hydrides of the alloys of the second samples A27-51 was extremely easy and rapid.

Example 4 Formula Ti, A1. following the procedure of Example 3. After production, an alloy represented by Ni (A and n are the same as in Example 3) was activated using hydrogen with a purity of 99.5% in the same manner as in Example 2, and then hydrogen was sealed and stored.

The storage rate and storage amount were almost the same as in Example 3, and the hydrogen release operation and release rate were similarly easy and quick.

Further, as a result of the 50 repeated storage and desorption tests of hydrogen with a purity of 99.5%, no deterioration in performance was observed in the above alloy.

Claims (1)

[Claims] 1. A hydrogen storage alloy represented by the general formula TinA1-oB. In the formula, A is AI, Cr, Cu, Fe, Mg, M
n, Mo. Si, Zn or Zr, 13 is Ni or Co, and n is a number ranging from 0.5 to 0.95. However, cases where B is Co and A is Fe are not included. 2. The hydrogen storage alloy according to claim 1, wherein B in the general formula is Ni. 3. The hydrogen storage alloy according to claim 1, wherein B in the general formula is Co. 4. The hydrogen storage alloy according to claim 1, wherein in the general formula, A is an element selected from Cr, Mn and Zr. 5. The hydrogen storage alloy according to claim 1 or 4, wherein n in the general formula is a number in the range of 0.8 to 0.95.