JP2007309457A - Hydrogen storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain hydrogen storage/release performance for a long period of time while suppressing alloy deterioration accompanied by the heat of hydrogen when stored and released. <P>SOLUTION: A single high pressure tank 11 stores at least two types of hydrogen storage alloys different in plateau pressure. The storage/release of hydrogen is dispersed under two or more plateau pressure to greatly change a hydrogen storage/release amount near the plateau pressure, thus preventing an abrupt change of a heat releasing value and a heat absorbing value to prevent the deterioration of the storage alloys. At least two types of storage alloys different in plateau pressure have the same element composition ands different composition ratios, or different element compositions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen storage tank using a hydrogen storage alloy, and more particularly to a hydrogen storage tank excellent in durability.

  Conventionally, for example, when storing hydrogen gas, it has been widely practiced to compress the hydrogen gas and fill it into a cylinder, or store it in a hydrogen storage alloy or a hydrogen adsorbing material capable of storing hydrogen.

  However, the cylinder has a small wall capacity because the wall thickness is large for a large volume. In addition, hydrogen storage alloys or the like do not necessarily have a high hydrogen storage density. For example, when they are mounted on a vehicle, the required storage density cannot be satisfied. For this reason, various studies have been made on techniques for increasing the packing density of hydrogen storage alloys and storing a large amount of hydrogen.

  On the other hand, hydrogen storage alloys (MH) are known to generate heat when hydrogen is absorbed and released. Therefore, in a usage mode in which hydrogen is temporarily stored and released as needed, in order to secure a large amount of hydrogen, if MH is attempted to absorb and release a large amount of hydrogen at a time, MH will increase rapidly. It will be accompanied by temperature changes from time to time.

  Hydrogen with a low-temperature MH tank (sub-tank) and a high-temperature MH tank (main tank) as one of the technologies for using hydrogen occluded using hydrogen-occlusion alloys in hydrogen-using devices such as fuel cells. A gas supply device has been proposed (see, for example, Patent Document 1).

  In this device, MH with high plateau pressure is used on the low temperature side and MH with low plateau pressure is used on the high temperature side, and hydrogen storage alloys generally release hydrogen when the plateau pressure (hydrogen dissociation equilibrium pressure) is low. For example, when the equilibrium pressure is relatively low, for example, when hydrogen is used, hydrogen is supplied from a sub-tank that can release hydrogen even under a low equilibrium pressure, and hydrogen can be supplied without heating the tank. For example, when a relatively small amount of hydrogen is sufficient, such as during cold start, the sub tank is given priority to cover the amount of hydrogen. In other words, a large amount of hydrogen is absorbed and released by the main tank having a larger capacity than that of the sub-tank. Therefore, the amount of heat change associated with the absorption and release of hydrogen in the main tank is large.

On the other hand, if the size of the device for storing and supplying hydrogen is too large, the volume efficiency in the case of mounting on a vehicle, for example, is poor. It is advantageous in terms of space.
JP 2000-12062 A

  The hydrogen storage alloy can store a large amount of hydrogen by increasing the filling density in the tank and supply it externally. This is an effective means from the viewpoint of solving the quantitative problem. Thus, if hydrogen is stored and released by MH using a single alloy, the amount of hydrogen stored / released at the plateau pressure is large, and the heat generation, that is, the change in calorific value is large. The degree of deterioration caused by the collapse of the crystal structure of the alloy is significant, and there is a problem that the storage / release amount of hydrogen cannot be maintained. In other words, the deterioration of long-term storage performance was spurred by the influence of heat.

  Further, even if the heat of the MH is controlled by a heat exchanger, the heat exchange efficiency cannot catch up with a rapid change in heat quantity, which is insufficient for avoiding deterioration of the alloy. If the number of cooling water pipes is increased in order to increase the heat exchange efficiency, the volume of MH becomes small and the hydrogen storage amount cannot be secured.

  The present invention has been made in view of the above, and an object of the present invention is to provide a hydrogen storage tank capable of suppressing deterioration due to rapid heat generation (caloric change) and maintaining hydrogen storage / release performance over a long period of time. And to achieve the purpose.

  In order to suppress a rapid temperature change in the tank accompanying the absorption and release of hydrogen while constituting a single tank so as not to reduce the volumetric efficiency, the present invention suppresses the plateau pressure of MH accommodated in the same tank. The present inventors have obtained knowledge that a configuration in which a plurality of values are changed is effective, and have been achieved based on such knowledge.

  In order to achieve the above object, the hydrogen storage tank of the present invention is configured by providing at least two hydrogen storage alloys having different plateau pressures and a tank containing at least two hydrogen storage alloys.

  In the hydrogen storage tank of the present invention, the hydrogen storage alloy contained in a single tank is a hydrogen storage alloy having a single composition (hereinafter, sometimes simply referred to as “MH”), and is constant. Rather than performing hydrogen absorption / release at a time under different plateau pressures, multiple types of hydrogen storage alloys with different plateau pressures can be accommodated in the same tank, and hydrogen absorption / release can be distributed under two or more plateau pressures. By doing so, it is possible to prevent the MH heat from deteriorating effectively by preventing the hydrogen absorption and release amount from changing greatly around the plateau pressure and preventing the heat generation amount and the heat absorption amount from changing suddenly. it can.

In other words, as shown in FIG. 2, in the configuration using two types of MH, hydrogen is absorbed and released in a wider pressure range than in the conventional configuration shown in FIG. When filling (storage), the generation amount of temperature per hour can be suppressed. FIG. 2 shows a PCT curve by the PCT method, and FIG. 5 is the same. The PCT method is a method according to JIS H 7201 (measurement method of hydrogen storage alloy pressure-isothermal line (PCT line)).
Therefore, the heat generated when hydrogen is absorbed and released can be efficiently removed by the heat exchanger, and the short-term deterioration of MH can be effectively suppressed. Thereby, the durability performance of the hydrogen storage tank, that is, the hydrogen storage / release efficiency (absorption / release properties) can be maintained over a long period of time.

  The hydrogen storage tank of the present invention can be configured to use two or more kinds of MH having the same elemental composition and different alloying element composition ratios as the hydrogen storage alloys (MH) having different plateau pressures, and having different plateau pressures. .

  Since the plateau pressure of MH can be changed by different composition ratios, rapid heat generation can be avoided even when a large amount of hydrogen is stored under a specific pressure, and deterioration of MH can be prevented.

  Further, as the hydrogen storage alloys (MH) having different plateau pressures, two or more kinds of MH having different elemental compositions can be used so as to have different plateau pressures. Also in this case, rapid heat generation can be avoided and deterioration of MH can be prevented.

  Furthermore, two or more MHs having the same elemental composition and different lattice constants may be used as the hydrogen storage alloys (MH) having different plateau pressures so that the plateau pressures are different. In this case as well, rapid heat generation can be avoided and deterioration of MH can be prevented.

  The difference in plateau pressure between hydrogen storage alloys having different plateau pressures is effectively 0.5 MPa or more. By setting the difference in plateau pressure within the above range, it is effective to suppress the amount of heat generated per hour during hydrogen filling (storage), and is effective in preventing the deterioration of MH.

  It is desirable that the heat generation amount at the time of hydrogen occlusion at each plateau pressure of the hydrogen occlusion alloys having different plateau pressures is substantially equal. Heat generation and heat absorption associated with the absorption and release of hydrogen are performed substantially equally, and it is effective to suppress a sudden increase in heat generation.

  ADVANTAGE OF THE INVENTION According to this invention, the hydrogen storage tank which suppresses the deterioration accompanying rapid heat_generation | fever (calorie | heat amount change) and can maintain the hydrogen storage / release performance over a long term can be provided.

Hereinafter, embodiments of the hydrogen storage tank of the present invention will be described in detail with reference to the drawings.
(First embodiment)
1st Embodiment of the hydrogen storage tank of this invention is described with reference to FIGS. 1-3 and FIG. The hydrogen storage tank of this embodiment is configured to accommodate two different plateau pressures by accommodating two kinds of hydrogen storage alloys having different elemental compositions in a pressure-resistant single tank.

In the present embodiment, a case where two types of hydrogen storage alloys (MH) of Ti ₂₅ Cr ₅₀ V ₂₅ and Ti ₃₆ Cr ₃₂ Mn ₃₂ are used as the hydrogen storage material filled in the tank will be mainly described. However, the present invention is not limited to the following embodiment.

As shown in FIG. 3, this embodiment includes a high-pressure tank 11 having a circular cross section, a Ti ₂₅ Cr ₅₀ V ₂₅ alloy 12 and a Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy 13 housed in the high-pressure tank 11, and cooling water. And a heat exchange pipe 14 for performing heat exchange with the MH and the atmosphere in the tank for cooling.

  As shown in FIG. 1, the high-pressure tank 11 is a hollow body that is formed into a cylindrical shape with a wall thickness of 10 mm and a diameter of 40 mm using stainless steel and is closed at both ends in the longitudinal direction of the cylinder. Has pressure resistance. As the wall thickness, cross-sectional shape, size, and the like, any thickness, rectangle, ellipse, and other shapes other than those described above can be selected according to the purpose and the like.

  A supply / exhaust pipe 15 for supplying and discharging hydrogen is attached to one end of the high-pressure tank 11 in the longitudinal direction. Hydrogen is supplied into the tank from the outside for storage, and the stored hydrogen is stored as necessary. It can be released to the outside.

  A hydrogen storage alloy (MH) is housed inside the tank. When hydrogen is supplied from the outside and the internal pressure of the tank is increased, hydrogen can be stored and stored, and the internal pressure of the tank is lowered as necessary. Sometimes, the hydrogen stored in MH dissociates, and the stored hydrogen can be released to the outside and supplied to a hydrogen-using device such as a fuel cell.

In the present embodiment, a Ti ₂₅ Cr ₅₀ V ₂₅ alloy 12 having a plateau pressure of 0.5 MPa and a Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy 13 having a plateau pressure of 8 MPa are accommodated in a high-pressure tank as hydrogen storage alloys. .

  The plateau pressure can be measured using a PCT measuring device [manufactured by Suzuki Shokan Co., Ltd.].

  In MH having different compositions, the plateau pressure (hydrogen dissociation equilibrium pressure) is different. Thus, in the prior art, hydrogen was absorbed and released at a time within a narrow pressure range as shown in FIG. 5, whereas in this embodiment, as shown in FIG. By absorbing and releasing hydrogen in the pressure range, and forming multiple plateau pressure regions where the amount of hydrogen storage / release increases, it is possible to suppress rapid heat generation per hour when storing hydrogen. it can. At this time, heat can be efficiently removed by the heat exchanger. As a result, it is possible to suppress the degradation of the alloy by suppressing the collapse of the crystal structure of MH due to heat, and to maintain the MH occlusion / discharge performance for a long time.

  The hydrogen storage alloy (MH) can be appropriately selected from known MHs having different plateau pressures so as to have a plurality of plateau pressures. For example, n types of MH having different elemental compositions have n equilibrium pressures (plateau pressures), and the pressure range where heat is generated can be widened.

  Examples of MH include binary alloys and ternary alloys. In addition to the above TiCrV alloys and TiCrMn alloys, LaNi alloys, MmNi alloys (Mm: Misch metal), TiCrMoV alloys, etc. It can be used suitably.

Specific examples of the _{MH, LaNi 5, Ti 25 Cr} 50 V 25, Ti 25 Cr 44 V 25 Fe 6, Ti 25 Cr 50 V 20 Mo 5, Ti 25 Cr 50 V 15 Mo 10, Ti 25 Cr 50 V 10 _{Mo 15, Ti 25 Cr 50 V} 20 Ni 5, Ti 11 Cr 12 V 71 Mo 5 Ni 1, Ti 36 Cr 32 Mn 32, Ti 30 Cr 35 , etc. _{Mn 35} and the like.

  Moreover, when combining MH so that plateau pressure may differ, it may be comprised so that it may have three, four types, or more different plateau pressures other than the case where there are two different plateau pressures.

Specifically, preferred combinations of MH having different compositions include a combination of Ti ₂₅ Cr ₄₄ V ₂₅ Fe ₆ and Ti ₂₅ Cr ₅₀ V ₂₀ Ni ₅ , Ti ₂₅ Cr ₅₀ V ₂₅ and Ti ₃₆ Cr ₃₂ Mn _32. the combination of a combination or LaNi ₅ and _Ti 25 _Cr 50 _V 20 Ni ₅ and _{Ti 25 Cr 50 V 20 Mo 5} , and the like.

  Among the above, the combination in which the difference in plateau pressure is 0.5 MPa or more is preferable, and the difference in plateau pressure is more preferably 4 MPa or more. If the difference in plateau pressure is within the above range, it is effective to keep the change in the calorific value accompanying the supply and release of hydrogen low, and is effective in preventing the deterioration of MH.

  Further, when providing a difference in the plateau pressure, it is desirable that the amount of heat generated during hydrogen storage at each plateau pressure is substantially equal. Here, “substantially equivalent” refers to the case where the difference in heat quantity is within the range of 100 J / Kg. A sudden increase in the amount of heat generation can be suppressed by the heat generation and heat absorption accompanying the absorption and release of hydrogen.

The form of the hydrogen storage alloy (MH) may be any shape and size such as powder, granule, and pellet.
The hydrogen storage alloy is obtained by, for example, arc melting metal powder so as to obtain a desired composition and composition ratio to obtain a crude alloy, which is then pulverized using a pulverizer such as a ball mill (preferably further annealed). The hydrogen storage tank of the present invention can be prepared by filling the tank with MH such as powder obtained (preferably with high density).

  The high-pressure tank 11 is provided with a heat exchange pipe 14 inside the tank through the tank wall from the other end opposite to one end where the supply / discharge pipe 15 is attached, and the MH accommodated in the tank. And it can cool by exchanging heat with the atmosphere in the tank. In the configuration having different plateau pressures as in this embodiment, heat exchange with cooling water can be performed more efficiently.

  FIG. 3 conceptually shows how MH is accommodated, but from the viewpoint of the amount of hydrogen stored, MH in the form of powder, granules, pellets, etc. so as not to create a space that does not contribute to hydrogen storage as much as possible. Is preferably packed in high density.

  Further, in the above, from the viewpoint of increasing the cooling efficiency by having different plateau pressures, the case where only the supply / discharge pipe 15 is arranged and heat exchange is shown, but the present invention is not limited to this, and a plurality of supply / exhaust depending on the case A heat exchanger such as a tube may be provided.

(Second Embodiment)
A second embodiment of the hydrogen storage tank of the present invention will be described. In this embodiment, in the first embodiment, two kinds of hydrogen storage alloys having the same elemental composition and different lattice constants are accommodated so as to have two different plateau pressures.
In addition, the same referential mark is attached | subjected to the component similar to 1st Embodiment, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 3, as in the first embodiment, as the hydrogen storage alloy, the first Ti ₂₅ Cr ₅₀ V ₂₅ alloy 16 having a plateau pressure of 1.3 MPa and the plateau pressure of 0.5 MPa are used. Ti ₂₅ Cr ₅₀ V ₂₅ alloy 17 is accommodated in a high-pressure tank.

The first Ti ₂₅ Cr ₅₀ V ₂₅ alloy 16 is arc-melted into an alloy using Ti powder, Cr powder, and V powder. After arc melting, for example, at room temperature (25 ° C.), it takes 1 to 10 hours. It can cool to 25-30 degreeC, and can obtain as a powdery material by grind | pulverizing. The lattice constant of the Ti ₂₅ Cr ₅₀ V ₂₅ alloy 16 obtained in this way is 0.302 nm.

The second Ti ₂₅ Cr ₅₀ V ₂₅ alloy 17 is arc-melted using Ti powder, Cr powder, and V powder to form an alloy, and after arc melting, for example, at 500 to 800 ° C./min with a copper roll. It can be obtained as a powder by quenching and grinding. The lattice constant of the Ti ₂₅ Cr ₅₀ V ₂₅ alloy 16 obtained in this way is 0.306 nm.

  The plateau pressure (hydrogen dissociation equilibrium pressure) differs between MHs having the same composition but different lattice constants. There are n equilibrium pressures (plateau pressures) of n types of MHs having different lattice constants, and the pressure range in which heat is generated can be broadened. Therefore, as shown in FIG. 2, hydrogen is absorbed and released in a wider pressure range, here two pressure ranges, and a plurality of plateau pressure ranges in which the hydrogen storage / release amount is increased are formed. Therefore, rapid heat generation per hour when storing hydrogen can be suppressed. At this time, heat can be efficiently removed by the heat exchanger. As a result, the degradation of the alloy can be suppressed by suppressing the collapse of the crystal structure of MH due to heat, and the MH occlusion / discharge performance can be maintained for a long time.

  Further, even in a combination having the same elemental composition and different lattice constants, a combination in which the difference in plateau pressure is 0.5 MPa or more is preferable, and more preferably 4 MPa or more.

  In the above, the lattice constant (that is, the plateau pressure) is changed by changing the cooling rate after arc melting, but MH having the same composition and different lattice constant can be obtained by using a metal having the same composition in addition to the above. It can also be prepared by a method such as mechanical milling.

In the present embodiment, the case where the Ti ₂₅ Cr ₅₀ V ₂₅ alloy is used has been described, but the same MH as that described in the first embodiment can be selected as the hydrogen storage alloy (MH), which is different. A desired configuration having a plateau pressure can be obtained.

(Third embodiment)
A third embodiment of the hydrogen storage tank of the present invention will be described. In this embodiment, in the first embodiment, two kinds of hydrogen storage alloys having the same elemental composition and different composition ratios are accommodated to have two different plateau pressures.
In addition, the same referential mark is attached | subjected to the component similar to 1st Embodiment, and the detailed description is abbreviate | omitted.

In the present embodiment, as shown in FIG. 3, as in the first embodiment, as the hydrogen storage alloy, the first Ti ₃₀ Cr ₃₅ Mn ₃₅ alloy 18 having a plateau pressure of 1.5 MPa and the Ti plate having a plateau pressure of 8 MPa are used. ₃₆ Cr ₃₂ Mn ₃₂ alloy 19 is housed in a high-pressure tank.

  The plateau pressure (hydrogen dissociation equilibrium pressure) differs between MHs having the same composition but different composition ratios. There are n equilibrium pressures (plateau pressures) of n types of MH having different composition ratios, and the pressure range in which heat is generated can be broadened. Therefore, as shown in FIG. 2, hydrogen is absorbed and released in a wider pressure range, here two pressure ranges, and a plurality of plateau pressure ranges in which the hydrogen storage / release amount is increased are formed. Therefore, rapid heat generation per hour when storing hydrogen can be suppressed. At this time, heat can be efficiently removed by the heat exchanger. As a result, the degradation of the alloy can be suppressed by suppressing the collapse of the crystal structure of MH due to heat, and the MH occlusion / discharge performance can be maintained for a long time.

  The hydrogen storage tank of this embodiment can also be produced similarly to the first embodiment. Specifically, for example, a titanium (Ti) powder, a chromium (Cr) powder, and a manganese (Mn) powder are arc-melted by a conventional method using an arc melting method to produce a crude alloy. After quenching with a roll or the like and pulverizing with a ball mill or the like, annealing is performed in vacuum (for example, at 900 ° C. for 3 hours) to obtain TiCrMn alloy powders having the same composition but different composition ratios. Can be prepared by filling the tank in a tank (preferably at a high density).

In the present embodiment, the case where Ti ₃₀ Cr ₃₅ Mn ₃₅ and Ti ₃₆ Cr ₃₂ Mn ₃₂ are combined has been described, but these and other composition ratios of TiCrMn alloys and other composition ratios of TiCrMn alloys are also described. It is also possible to configure a combination of different composition ratios by selecting MH other than the TiCrMn-based alloy mentioned in the first embodiment, and to have a desired plateau pressure. It can be set as this structure.

As a preferable combination mode of MH having the same elemental composition but different composition ratio, in addition to the above, a combination of Ti ₂₅ Cr ₅₀ V ₂₀ Mo ₅ and Ti ₂₅ Cr ₅₀ V ₁₅ Mo ₁₀ , Ti ₂₅ Cr ₅₀ V ₂₀ Mo ₅ And a combination of Ti ₂₅ Cr ₅₀ V ₁₀ Mo ₁₅ and the like.

  Further, even in a combination having the same elemental composition but different composition ratios, a combination in which the difference in plateau pressure is 0.5 MPa or more is preferable, and more preferably 4 MPa or more.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
-Sample preparation-
Arc melting method using 4.72 g of titanium (Ti) powder [particle size 100 μm], 10.25 g of chromium (Cr) powder [particle size 100] and 5.02 g of vanadium (V) powder [particle size 100 μm] A crude alloy was prepared by arc melting by a conventional method, and after arc melting, it was rapidly cooled at 700 ° C./min using a copper roll and pulverized using a ball mill. Thereafter, annealing treatment was performed in vacuum at 900 ° C. for 3 hours to obtain TiCrV alloy powder.

The obtained TiCrV alloy composition and the composition ratio was calculated as follows: _{Ti 25 Cr} 50 _V 25 by ICP emission spectrometry. The plateau pressure of Ti ₂₅ Cr ₅₀ V ₂₅ was 0.5 MPa as a result of PCT measurement using a PCT measurement device (manufactured by Suzuki Shokan Co., Ltd.).

  Next, 6.70 g of titanium (Ti) powder [particle size 100 μm], 6.47 g of chromium (Cr) powder [particle size 100 μm], and 6.83 g of manganese (Mn) powder [particle size 100 μm] were used, The same operation as described above was performed to obtain TiCrMn alloy powder.

Similarly to the above, the composition and composition ratio of the obtained TiCrMn alloy were Ti ₃₆ Cr ₃₂ Mn ₃₂ , and the plateau pressure of Ti ₃₆ Cr ₃₂ Mn ₃₂ obtained in the same manner was 8 MPa.

-Production of hydrogen storage tank-
As shown in FIG. 4, a cylindrical high pressure tank (pressure resistance 35 MPa) 21 made of a stainless steel SUS310 having a circular cross section and an internal volume of 60 ml (excluding a heat exchange tube) was prepared. One end of the high-pressure tank 21 has an opening structure, and an Al filter (made of aluminum, hole size: 0.5 μm) 22 is attached to the opening. One end to which the Al filter 22 is attached communicates with the needle valve 23 through an Al filter and piping. The tank is sealed by opening and closing the valve, and hydrogen is supplied into the tank through the Al filter 22. In addition, the stored hydrogen can be released (discharged).

  The needle valve 23 is connected to a hydrogen supply pipe (not shown) that communicates with an external hydrogen supply device. When the needle valve 23 is opened and hydrogen is supplied to the high pressure from the hydrogen supply pipe through the Al filter, hydrogen is supplied into the tank. It can be stored (occluded), and the stored hydrogen can be released when the needle valve 23 is opened and decompressed as necessary.

At the other end of the high-pressure tank 21, a heat exchange tube (outer diameter φ2 mm, inner diameter φ1.5 mm, surface area 0.2 m ² , water circulation rate 100 ml / min, cooling water temperature 20 ° C. [constant]) 24 is attached. A circulation system is constructed in which cooling water flows from the outside of the tank into the tank, is inserted into the tank, and is discharged from the other end to the outside of the tank again. As a result, the MH (Ti ₂₅ Cr ₅₀ V ₂₅ and Ti ₃₆ Cr ₃₂ Mn ₃₂ ) inside the tank and the atmosphere in the tank are cooled by heat exchange with the cooling water.

In the high-pressure tank 21 configured as described above, 5 g of Ti ₂₅ Cr ₅₀ V ₂₅ alloy powder obtained above and 5 g of Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy powder are mixed in advance using a V-type powder mixer. The powdered and kneaded powder was filled into the tank with high density and then sealed to prepare a hydrogen storage tank.

-Measurement-
Next, the needle valve 23 was opened, and 35 MPa hydrogen gas was supplied into the tank through the Al filter. Thereafter, the needle valve 23 was closed and held for 5 minutes. After 5 minutes, the needle valve was opened again, and hydrogen gas was released through the Al filter to atmospheric pressure. This operation was repeated 100 times (cycles), and the hydrogen release amount was measured by the PCT method according to JIS H 7201 (measurement method of hydrogen storage alloy pressure-isothermal curve (PCT line)). The measurement results are shown in Table 1 below.

(Example 2)
In Example _1, Ti _{25 Cr} 50 _{V 25} alloy powder and _Ti 36 _Cr 32 _{Mn 32} alloy powder was produced by the following method, different lattice constants composition identical _Ti 25 _Cr 50 _{V 25} alloy powder 1 and Ti _A hydrogen storage tank was prepared and the amount of hydrogen released was measured in the same manner as in Example 1 except that the ₂₅ Cr ₅₀ V ₂₅ alloy powder 2 was used. The measurement results are shown in Table 1 below.

-Sample preparation-
Arc melting method using 61.3 g of titanium (Ti) powder [particle size 100 μm], 133.3 g of chromium (Cr) powder [particle size 100 μm], and 65.3 g of vanadium (V) powder [particle size 100 μm] A crude alloy was prepared by arc melting by the usual method according to 1. After the arc melting, it was allowed to cool to 25 ° C. over 9 hours at room temperature (25 ° C.), and this was pulverized using a ball mill. Thereafter, annealing treatment was performed in vacuum at 900 ° C. for 3 hours to obtain TiCrV alloy powder 1.

The TiCrV alloy powder 1 was confirmed to have a composition of Ti ₂₅ Cr ₅₀ V ₂₅ by the same method as in Example 1. Further, the lattice constant of the TiCrV alloy powder 1 was 3.01 mm as a result of XRD measurement, and the plateau pressure obtained by the same method as in Example 1 was 1.0 MPa.

  Next, the same amount of Ti powder, Cr powder and V powder as TiCrV alloy powder 1 was used to produce a crude alloy in the same manner, and then cooling by cooling after arc melting was performed at 600 ° C./min with a copper roll. A TiCrV alloy powder 2 was obtained in the same manner as the TiCrV alloy powder 1 except that the method was changed to a rapid cooling method.

The composition of TiCrV alloy powder 2 was confirmed to be Ti ₂₅ Cr ₅₀ V ₂₅ by the same method as in Example 1. The lattice constant of TiCrV alloy powder 2 was 3.03 mm as a result of performing the same method as described above, and the plateau pressure obtained by the same method as in Example 1 was 0.1 MPa.

(Example 3)
In Example 1, Ti ₂₅ Cr ₅₀ V ₂₅ alloy powder and Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy powder were replaced with Ti ₂₅ Cr ₂₅ V ₅₀ alloy powder and Ti ₃₀ Cr ₃₅ Mn ₃₅ alloy powder prepared by the following method. Except that, a hydrogen storage tank was prepared and the hydrogen release amount was measured in the same manner as in Example 1. The measurement results are shown in Table 1 below.

-Sample preparation-
Titanium powder [particle size 100 μm] 4.75 g, chromium powder [particle size 100 μm] 5.15 g and vanadium powder [particle size 100 μm] 10.10 g were arc-melted by a conventional method using arc melting method. A crude alloy was prepared, and after arc melting, it was rapidly cooled with a copper roll at 600 ° C./min, and pulverized using a ball mill. Thereafter, annealing treatment was performed in vacuum at 900 ° C. for 3 hours to obtain TiCrV alloy powder.

  Next, 5.55 g of titanium powder [particle size 100 μm], 7.03 g of chromium powder [particle size 100 μm], and 7.42 g of manganese powder [particle size 100 μm] are used, and arc arc melting is performed in a conventional manner. A crude alloy was prepared by melting, rapidly melted at 600 ° C./min with a copper roll after arc melting, and pulverized using a ball mill. Thereafter, an annealing treatment was performed in vacuum at 900 ° C. for 3 hours to obtain TiCrMn alloy powder.

The TiCrV alloy powder and TiCrMn alloy powder obtained from the above were confirmed to be Ti ₂₅ Cr ₂₅ V ₅₀ and Ti ₃₀ Cr ₃₅ Mn ₃₅ by the same method as in Example 1, respectively. Moreover, the plateau pressure calculated | required by the method similar to Example 1 was 0.1 MPa and 10 MPa, respectively.

(Comparative Example 1)
In Example _1, except that instead of Ti _{25 Cr} 50 _{V 25} alloy powder 5g and _Ti 36 _{Cr 32 Mn} 32 alloy powder 5g into _{Ti 25 Cr} 50 _V 25 alloy powder 10 g, in the same manner as in Example 1, the hydrogen storage While producing the tank, the hydrogen release amount was measured. The measurement results are shown in Table 1 below.

  As shown in Table 1, in the examples having different plateau pressures, heat generation (change in calorific value) when hydrogen is repeatedly absorbed and released is significantly suppressed as compared with the comparative example in which the plateau pressure is single. The amount of decrease in the hydrogen release amount after repeating the absorption and release of 100 cycles was also small. In other words, thermal deterioration of MH accompanying a large amount of hydrogen occlusion by repeating hydrogen absorption and desorption was suppressed, and a significant reduction in hydrogen occlusion / release efficiency could be prevented.

It is a schematic perspective view which shows the hydrogen storage tank which concerns on 1st Embodiment. It is a graph which shows the relationship between the hydrogen storage amount and hydrogen pressure of the hydrogen storage tank which concerns on 1st Embodiment which has two types of MH from which a plateau pressure differs. It is a schematic sectional drawing which shows the structure of the hydrogen storage tank which concerns on 1st Embodiment. 2 is a schematic cross-sectional view showing a configuration of a hydrogen storage tank produced in Example 1. FIG. It is a graph which shows the relationship between the hydrogen storage amount and hydrogen pressure of the conventional hydrogen storage tank which has a kind of MH.

Explanation of symbols

11, 21 ... High pressure tank 12 ... Ti ₂₅ Cr ₅₀ V ₂₅ alloy 13 ... Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy 16, 17 ... Ti ₂₅ Cr ₅₀ V ₂₅ alloy 18 ... Ti ₃₀ Cr ₃₅ Mn ₃₅ alloy 19 ... Ti ₃₆ Cr ₃₂ Mn ₃₂ alloy

Claims (6)

  A hydrogen storage tank comprising at least two types of hydrogen storage alloys having different plateau pressures and a tank for storing the at least two types of hydrogen storage alloys.   2. The hydrogen storage tank according to claim 1, wherein the hydrogen storage alloys having different plateau pressures include at least two kinds having the same elemental composition and different composition ratios.   The hydrogen storage tank according to claim 1 or 2, wherein the hydrogen storage alloys having different plateau pressures include at least two elements having different elemental compositions.   4. The hydrogen storage tank according to claim 1, wherein the hydrogen storage alloys having different plateau pressures include at least two types having the same elemental composition and different lattice constants. 5.   The hydrogen storage tank according to any one of claims 1 to 4, wherein a difference in plateau pressure between hydrogen storage alloys having different plateau pressures is 0.5 MPa or more.   The hydrogen storage tank according to any one of claims 1 to 5, wherein the at least two kinds of hydrogen storage alloys have substantially the same amount of heat generation during hydrogen storage at each plateau pressure.

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