KR20230099283A - Method of manufacturing a hydrogen storage material used chloride catalisyst - Google Patents

Abstract

The present invention relates to a hydrogen storage material and a manufacturing method thereof, wherein the hydrogen storage material includes a metal complex hydride complex. The manufacturing method of the hydrogen storage material of the present invention can provide a hydrogen storage composite having high hydrogen release characteristics by mixing the hydrogen storage material and the catalyst, which can be applied to fuel cell vehicles and the like. In addition, it is possible to provide a hydrogen storage material having improved hydrogen weight storage density and hydrogen absorption/release temperature characteristics compared to hydrogen storage alloys.

Description

Manufacturing method of solid hydrogen storage material using a chloride-based catalyst

Embodiments of the present invention relate to a method for manufacturing a hydrogen storage material for storing hydrogen gas.

Hydrogen is a clean energy source that generates water by reacting with oxygen without generating carbon dioxide during combustion, and is attracting attention as a next-generation energy source because it can be fused with renewable energy such as solar and wind power. However, since hydrogen is a gas at room temperature, it is necessary to develop efficient hydrogen transportation and storage technologies in order to utilize it as an energy source for various industries.

Methods for storing hydrogen include high-pressure gas storage, low-temperature liquefied storage, and solid hydrogen storage. Solid hydrogen storage technology is a technology that stores hydrogen on the surface or inside of a material, and can store hydrogen at a higher density than other storage technologies. It has low price and high stability.

Currently, countries such as the United States, Japan, and Europe are actively promoting research and development of high-capacity solid hydrogen storage materials for transportation devices and stationary fuel cells. Since the 1980s in Japan, the United States and Europe, research on hydrogen storage alloys, which have been used as electrode materials for secondary batteries, has been actively conducted. Although it has the advantage of having a high volume storage density, it cannot overcome the disadvantage of having a low weight storage density of 2 wt% or less.

Research on metal complex hydrides for hydrogen storage has been conducted since it was known by Bogdanovic et al. in 1997 that adding a small amount of a titanium-based catalyst to sodium aluminum hydride (NaAlH ₄ ) lowers the dehydrogenation reaction temperature and improves reversibility. However, materials for hydrogen storage that have been developed so far need to be improved in order to be commercialized, so various studies are being conducted.

The problem to be solved by the embodiments of the present invention is to provide a method for manufacturing a hydrogen storage material.

According to one embodiment of the present invention, the hydrogen storage material includes an alanate-based metal complex hydride composite. The hydrogen storage material is a composite obtained by mixing an alanate-based metal complex hydride with at least one catalyst selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ . The hydrogen storage material may be activated under a hydrogen pressurized atmosphere. In the hydrogen storage material according to the present invention, NaH, Al, and the catalyst may be mixed in a 1:1:1 mol% ratio.

Another embodiment of the present invention relates to a method for manufacturing a hydrogen storage material, comprising: (a) synthesizing by mixing NaH and aluminum (Al); and (b) generating a composite for hydrogen storage by mixing at least one catalyst selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ with the compound of step (a). The manufacturing method of the hydrogen storage material may further include (c) activating the hydrogen storage complex produced in step (b).

In the step (a), NaH and aluminum may be added at a mol% ratio of 1:1. In step (b), the compound of step (a) and one or more catalysts selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ may be added at a mol% ratio of 1:1. The activating the hydrogen storage complex of step (c) may be performed in a hydrogen pressurized atmosphere.

According to embodiments of the present invention, a hydrogen storage material and a catalyst may be mixed to provide a hydrogen gas storage composite having high hydrogen release characteristics, which may be applied to a fuel cell vehicle or the like. In addition, it is possible to provide a hydrogen storage material having improved hydrogen weight storage density and hydrogen absorption/release temperature characteristics compared to hydrogen storage alloys.

1 is an X-ray diffraction graph of a hydrogen storage material prepared according to an embodiment of the present invention.
2 and 3 are data showing an isothermal hydrogen release curve and a maximum hydrogen release curve of a hydrogen storage material prepared according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail. In addition, in describing the present invention, a detailed description of a related general-purpose configuration or function will be omitted.

A hydrogen storage material according to an embodiment of the present invention includes an alanate-based metal complex hydride composite. The hydrogen storage material is a composite obtained by mixing an alanate-based metal complex hydride with at least one catalyst selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ . The hydrogen storage material may be activated under a hydrogen pressurized atmosphere.

Metal complex hydride-based solid hydrogen storage materials are largely classified into alanate-based, amide-based, imide-based, and borohydride-based materials. The alanate-based NaAlH ₄ is a Ti-containing catalyst It is known that reversible hydrogen uptake and release is possible with a weight storage density of around 4wt% at around 150 ° C. Alanate is a generic term for salts containing tetra-hydro-aluminium ion (AlH4-). NaAlH ₄ contains as much hydrogen as 7.5% by mass.

In the case of a metal complex hydride, the material itself does not exhibit the properties of a hydrogen storage material, and when a catalyst is uniformly dispersed in the metal complex hydride, the properties appear only and can be called a hydrogen storage material.

In embodiments of the present invention, NaAlH ₄ , which is the main hydrogen storage material, can be synthesized by a dry method or a wet method. In one embodiment of the present invention, NaAlH ₄ may be synthesized by a dry method. When produced by the dry method, the purity is higher than when produced by the wet method, and the manufacturing process is not complicated compared to the wet method, which requires secondary processing such as filtering and drying after production. As a method of uniformly dispersing the catalyst on a nanoscale in the solid phase, various known methods other than high-energy ball milling may be used, and high-energy ball milling may be effective.

A method for manufacturing a hydrogen storage material according to embodiments of the present invention includes (a) synthesizing NaAlH ₄ by mixing NaH and aluminum (Al); and (b) generating a composite for hydrogen storage by mixing at least one catalyst selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ with the compound of step (a).

Step (a) is a step of synthesizing a metal complex hydride, which is a step of mixing and synthesizing raw materials. For example, NaH and aluminum (Al) may be mixed and synthesized by adding NaH and aluminum (Al) at a mole % ratio of 1:1 to a synthesis vessel and ball milling under a hydrogen atmosphere. Ball milling may be performed using a shaker mill, a vibratory mill, a planetary mill, or an attritor mill.

According to embodiments of the present invention, NaH, aluminum (Al), and balls are first introduced into a reaction vessel for ball milling. After that, the reaction vessel is filled with hydrogen (H ₂ ) gas. For example, hydrogen (H ₂ ) gas may be pressurized up to 3 bar at a rate of 100 cc/min. Ball milling can then be performed by milling the raw material using a ball and reaction vessel.

Here, the material of the ball and the reaction vessel may be tool steel, stainless steel, cemented carbide (WC-Co), silicon nitride (Si ₃ N ₄ ), alumina, or zirconia. These may be used alone or in combination. The ball may have a diameter of about 5 mm to about 30 mm.

Step (a) may be performed for 3 hours to 6 hours at a speed of 200 rpm to 800 rpm, for example. If the time of step (a) is shorter than the above range, the raw material is not evenly dispersed and the size of crystal grains is not reduced, so that the solid phase reaction rate cannot be increased. On the other hand, if the time is prolonged, the production yield may decrease.

Step (b) is a step of uniformly dispersing a catalyst in the metal complex hydride synthesized in step (a) to form a complex for storing hydrogen. Digested product and one or more catalysts selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ may be added at a mol% ratio of 1:1. For example, the metal complex hydride NaAlH ₄ and CeCl ₃ catalyst, which are the compounds of the step (a), were put into a synthesis vessel at a mole % ratio of 1:1 and ball-milled under a hydrogen atmosphere to form a complex to obtain a NaAlH ₄ -CeCl ₃ complex. can form For example, hydrogen (H ₂ ) gas may be pressurized up to 3 bar at a rate of 100 cc/min. Ball milling may be performed using a shaker mill, a vibratory mill, a planetary mill, or an attritor mill. The step (b) may be performed for 3 hours to 6 hours at a speed of 200 rpm to 800 rpm, for example.

The metal complex hydride complex, which is the hydrogen storage material prepared in step (b), may be activated through step (c) of additional activation. The step of activating the hydrogen storage complex of step (c) may be further performed in a hydrogen pressurized atmosphere. For example, step (c) may be performed for 10 minutes to 100 minutes at a temperature range of 300 to 600 ° C. in an atmosphere where the metal complex hydride synthesized in step (b) is pressurized with hydrogen. The hydrogen pressure may be 100 bar. For example, 100 g of the metal complex hydride complex, which is the hydrogen storage material prepared in step (b), is placed in a high-pressure container, and hydrogen (H ₂ ) gas is introduced at a rate of 100 cc/min to 100 g. After pressurization to bar, the temperature may be raised to 300 ° C. at a heating rate of 10 ° C. and activated for 100 minutes, but is not limited thereto.

In the hydrogen storage material manufactured according to the embodiments of the present invention, the operating temperature is reduced, the hydrogen intake and release rate is increased, and cycle characteristics can be improved. The pure NaAlH ₄ prepared in step (a) has a hydrogen evolution temperature of about 170 to 180 °C, but the hydrogen evolution temperature is relatively lowered to about 120 to 130 °C when the CeCl ₃ catalyst is added in step (b). As for other catalysts, the hydrogen evolution temperature is lowered to 120°C when the TiCl ₃ catalyst is added, 130°C when the NdCl ₃ catalyst is added, and 140°C when the SmCl ₃ catalyst is added.

In manufacturing or storing the hydrogen storage material, since NaAlH ₄ generates aluminum molecules during the reaction as shown in the following reaction formula, a metal surface coating or deposited container may be used to prevent the reaction with the storage container.

(Reaction Formula) NaAlH ₄ → 1/3 Na ₃ AlH ₆ + 2/3 Al + H ₂ (3.7% by mass)

1/3 Na ₃ AlH ₆ → NaH + 1/3 Al + 1/2 H ₂ (1.9% by mass)

Hereinafter, the present invention will be described in more detail through examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited by the examples presented below.

Example 1: Preparation of hydrogen storage material

First, NaH, aluminum (Al), and balls are introduced into a reaction vessel at a 1:1 mol% ratio, and hydrogen (H ₂ ) gas is pressurized to 3 bar at a rate of 100 cc/min in the reaction vessel. , and mixed at a speed of 400 rpm for 3 hours to synthesize a solid hydrogen storage material (NaAlH ₄ ). Then, CeCl ₃ catalyst was added to the synthesized solid hydrogen storage material in a ratio of 1:1 mol% to a synthesis vessel, and hydrogen (H ₂ ) gas was pressurized to 3 bar at a rate of 100 cc/min in the synthesis vessel, After mounting on a planetary mill, mixing at a speed of 400 rpm for 3 hours to synthesize a solid hydrogen storage composite (NaAlH ₄ -CeCl ₃ ). Finally, put 100 g of the synthesized solid hydrogen storage complex in a high-pressure container, pressurize the H ₂ gas to 100 bar at a rate of 100 cc/min, and then raise the temperature to 300° C. at a temperature increase rate of 10° C./min for 100 minutes. Activated to prepare a hydrogen storage material.

Component analysis experiment of hydrogen storage material

1 is X-ray diffraction spectroscopy (XRD) data analyzed to confirm the synthesis of solid hydrogen storage composites synthesized for each chloride-based catalyst, confirming that NaAlH ₄ was successfully synthesized. can

Hydrogen release rate measurement experiment

2 is data showing isothermal hydrogen release curves and maximum hydrogen release curves measured with Sievert equipment at a release temperature of 120 ° C and FIG. ₃ is a release temperature of 150 ° C. It can be confirmed that this is the maximum hydrogen emission amount.

Above, the embodiments of the present invention have been described, but the above-described embodiments are some of the 'examples' that can deliver the scope of protection of the present invention described in the following claims. Therefore, the protection scope of the present invention is not limited to the above-described embodiments.

In addition, the protection scope of the present invention can be extended to the scope technically equivalent to the scope of the claims.

Claims (5)

(a) synthesizing by mixing NaH and aluminum (Al); and
(b) mixing at least one catalyst selected from the group consisting of CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ with the compound of step (a) to create a hydrogen storage material; manufacturing method.
The method of claim 1, wherein the method of manufacturing a hydrogen storage material further comprises the step of (c) activating the hydrogen storage composite produced in step (b).
The method of claim 1, wherein in step (a), NaH and aluminum are added in a mole % ratio of 1:1.
The hydrogen according to claim 1, wherein in step (b), the compound of step (a) and a catalyst such as CeCl ₃ , TiCl ₃ , NdCl ₃ and SmCl ₃ are added at a mole% ratio of 1:1. Manufacturing method of storage material.
The method of claim 2, wherein the step of activating the hydrogen storage complex in step (c) is performed in a hydrogen pressurized atmosphere.

Images