KR101127956B1 - Method for manufacturing material for hydrogen storage containing graphite powder and material for hydrogen storage manufactured by the same - Google Patents

Abstract

The present invention relates to a method for producing a hydrogen storage material containing graphite powder and to a hydrogen storage material prepared by the method, and more specifically, to graphite powder mechanically pulverized by ball milling to contain a graphite powder which improves hydrogen storage capacity. It relates to a method for producing a hydrogen storage material and to a hydrogen storage material prepared by the above method including a graphite powder with improved hydrogen storage capacity. According to the present invention it is possible to significantly improve the hydrogen storage capacity of the hydrogen storage medium.

Hydrogen storage capacity, hydrogen storage material, ball milling

Description

METHOD FOR MANUFACTURING MATERIAL FOR HYDROGEN STORAGE CONTAINING GRAPHITE POWDER AND MATERIAL FOR HYDROGEN STORAGE MANUFACTURED BY THE SAME}

The present invention relates to a method for producing a hydrogen storage material using mechanical processing, and more particularly, to a method for producing a hydrogen storage material and a hydrogen storage material manufactured by increasing the hydrogen storage capacity by processing graphite.

Recently, as the industry is advanced, the use of fossil fuels has increased significantly, causing problems such as global warming. Accordingly, there is an urgent need to develop new environmentally friendly energy sources that can replace fossil fuels. One of the emerging alternative energy sources is hydrogen energy. The hydrogen storage methods developed to date include low temperature liquid hydrogen storage, high pressure gas hydrogen storage, hydrogen storage alloys, and adsorption using adsorption. Low-temperature liquid hydrogen storage has an energy density of 4-5 times higher than that of high-pressure gas hydrogen storage, but consumes about 10-14 kWh of electricity per kg of hydrogen. There is a disadvantage that the loss amount is very large. In addition, the hydrogen storage alloy can safely store hydrogen at a pressure of 20-40 atm or less at room temperature, but the weight is heavy and expensive, and even in the hydrogen storage capacity is lower than gasoline or diesel, there is difficulty in reversible hydrogen storage. In the case of high pressure gas hydrogen storage, it is necessary to use a container that can withstand high pressure because it needs to be stored at a high pressure of 700 atm or higher, and there is a safety problem because there is always a risk of explosion due to leakage of hydrogen. . Thus, the need for a technique to store hydrogen at room temperature and relative low pressure (100 atmospheres) using the adsorption method has been highlighted.

Porous carbon materials contain a large number of micropores in their structure and have a very large specific surface area, which has been utilized as an adsorbent for various gases. In particular, the carbon material can control the pore structure, and is easy to improve performance through the design of the pore structure according to the particle diameter of the gas. In addition, it has a plurality of outermost hydrogen on the surface, it is possible to give a variety of functional groups through various surface treatment, through which it is possible to give a selective adsorption capacity for polar gas.

Hydrogen storage using carbon is not only safer than high pressure hydrogen and liquefied hydrogen storage, but also inexpensive, and most of all, the reaction is reversible and thus can be used semi-permanently.

However, pure carbon material itself lacks affinity with hydrogen molecules, and hydrogen storage at room temperature is far below expectations due to low adsorption energy of carbon material to hydrogen molecules.

Graphite is a carbon material having a layered structure in the horizontal direction, and each layer is composed of physical bonds, and thus, when a constant force is applied, the graphite may be deformed, that is, delamination or peeling. Using these properties, it is possible to design the desired pore and structure by using the proper treatment technique.

As a result of our diligent efforts to solve this problem, the present inventors have crushed natural graphite by a ball milling method under certain conditions to generate new pores and to expose hydrogen adsorption points, thereby improving the hydrogen storage ability of graphite. This invention was completed by confirming that it can raise significantly.

Accordingly, it is an object of the present invention to provide a method for producing a hydrogen storage material containing graphite powder mechanically ground by a ball milling method.

Another object of the present invention is to provide a hydrogen storage material containing graphite powder mechanically pulverized by a ball milling method.

The objects and advantages of the present invention will become more apparent from the following detailed description, claims and drawings.

In order to achieve the above object, the present invention comprises the steps of pulverizing the graphite and the ball into a sealed reaction vessel and ball milling; And it provides a method for producing a hydrogen storage material containing a graphite powder comprising the step of recovering the graphite powder obtained by grinding.

In addition, the present invention comprises the steps of mechanically grinding the graphite in a sealed reaction vessel by a ball milling method; And it provides a hydrogen storage material containing the graphite powder produced by the step of recovering the graphite powder obtained by grinding.

The present invention has the advantage that it is possible to secure the energy saving and stability required for hydrogen storage as a technology that enables the practical use of hydrogen energy, which has been spotlighted as a future energy source.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of putting graphite and balls in a sealed reaction vessel and milling by ball milling; And it provides a method for producing a hydrogen storage material containing a graphite powder comprising the step of recovering the graphite powder obtained by grinding.

The environment inside the reaction vessel of the present invention is maintained by adding an inert gas or active gas, it is preferable to add nitrogen, helium or argon as the inert gas, oxygen or ammonia is preferably added as the active gas, This is not restrictive.

The term "graphite" of the present invention is used as meaning including all kinds of graphite which can be used for ball milling. Therefore, the graphite should be understood as including all kinds of graphite as long as it can be used for ball milling, whether artificial graphite or natural graphite, or earth graphite if it is natural graphite or impression graphite.

The graphite also includes graphite powder that has been ball milled.

Therefore, the graphite powder of the present invention is understood as a meaning including the graphite powder obtained by ball milling the graphite powder which has already been ball milled.

The phase of the graphite of the present invention is preferably in the form of powders, flakes or plates, but is not limited thereto.

The ball of the present invention uses a diameter of 1 to 20 mm, preferably a diameter of 1 to 10 mm, and alumina, iron, kaolin, zirconium or silicate is used. It is not limited to the material described above as long as it is a material that does not cause breakage during reaction.

The volume ratio (v / v) of the balls / graphite to be put into the container of the present invention is 0.5 to 5, preferably 1 to 2.

On the other hand, the ball milling process (Ball Milling Process) was used to manufacture the graphite powder of the present invention, wherein the ball milling method is a powder particles such as a metal or a ceramic powder is charged with a plurality of balls (ball) in a container to It refers to a process of applying high mechanical energy by repeating the process of crushing the compressed particles again by pressing the powder particles with each other by contacting the balls or contact between the balls and the container while mixing. This ball milling method has been used for mechanical grinding or mechanical alloying to obtain fine powder.

The mechanical energy exerted by such ball milling is the ball milling speed (the running speed of the machine, which means the idle speed of the vessel in which the ball milling takes place). It may vary depending on variables such as ball milling time, volume ratio of the ball and the raw material, and / or ball size. In an embodiment of the present invention, the container state is nitrogen, oxygen, or ammonia gas, and room temperature. Graphite was ball milled under the following conditions using a ball mill device manufactured in-house at 25 ° C.

The ball milling of the present invention is reacted at a speed of 100 to 2000 rpm, preferably at a speed of 100 to 1500 rpm. The reaction time takes too long at rpm of the steel bar in the reactor is too low, the ball is damaged at too high rpm to increase the content of foreign matter in the final graphite powder.

The ball milling of the present invention is reacted for a time of 1 minute to 120 minutes. If the contact time between the ball and graphite is less than 1 minute, the reaction hardly occurs. If it is more than 120 minutes, excessive thermal and mechanical energy is supplied by the ball milling to completely fine powder, which is not suitable for hydrogen storage.

Ball milling of the present invention is reacted at a temperature of room temperature to 100 ℃. The term "room temperature" of the present invention means a temperature in a state in which a state of a material is kept constant, and generally refers to 15 to 25 ° C, but is not limited to the temperature if the state of a material is maintained.

In addition, the present invention comprises the steps of mechanically grinding the graphite in a sealed reaction vessel by a ball milling method; And it provides a hydrogen storage material containing the graphite powder produced by the step of recovering the graphite powder obtained by grinding.

In the "graphite powder" of the present invention, the graphite layer interval is controlled so that the hydrogen storage value is 0.01 to 10% by weight, preferably 0.2 to 5% by weight, based on the total weight of the graphite powder.

The atmosphere inside the reaction vessel of the present invention, the graphite phase, the diameter and material of the ball, the ball milling speed, the ball milling time, and the ball milling temperature are as described above in the production method.

Hereinafter, the present invention will be described in more detail with reference to Examples.

It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

In the present invention, each characteristic value was measured by the following method.

Measurement example  1.Measurement method of graphite powder volume before and after reaction. (%)

As the physical properties of the prepared functional graphite, the volume increase rate of the graphite powder was measured by comparing the volume of natural graphite (1 g), a raw material, and the volume after ball milling with a measuring cylinder, using a ratio of volume per unit weight.

Measurement example  2. Method of measuring hydrogen storage amount (% by weight) of graphite powder volume before and after reaction.

In order to measure the hydrogen storage of functional graphite, each sample was degassed for 6 h while the residual pressure was maintained at 10 ⁻³ torr or lower at 573 K, followed by conditions of 298 K and 100 atm using BEL-HP (BEL Japan). The hydrogen storage amount was measured at. The hydrogen storage measurement method was a step-by-step method, and the average sample volume was 0.5g.

Example  One.

10 g of natural graphite was placed in a ball mill reaction vessel having a volume of 500 ml and filled with 250 ml of alumina balls having a diameter of 10 mm, and then purged with N ₂ in the vessel. The reaction vessel was rotated at 100 rpm and milled for about 1 minute, at which time the temperature was 25 ° C.

In the present example, before and after the treatment, the volume increase rate of the graphite powder was 5%, and the hydrogen storage amount increased by 50% (0.2 wt% → 0.3 wt%) (Table 1 and Table 2).

Example  2.

10 g of natural graphite was placed in a 500 ml volume ball mill reaction vessel, filled with alumina balls (alumina balls) having a diameter of 10 mm to 250 ml, and the vessel was purged with N ₂ . The reaction vessel was fixed at 200 rpm and milled for about 10 minutes, at which time the temperature was 25 ° C.

In the present Example, before and after the treatment, the volume increase rate of the graphite powder was 50%, and the hydrogen storage amount increased by 400% (0.2 wt% → 1.0 wt%) (Table 1 and Table 2).

Example  3.

10 g of natural graphite was placed in a 500 ml volume ball mill reaction vessel, filled with alumina balls (alumina balls) having a diameter of 10 mm to 250 ml, and the vessel was purged with N ₂ . The reaction vessel was fixed at 400 rpm and milled for about 30 minutes, at which time the temperature was 25 ° C.

In the present embodiment, before and after the treatment, the volume increase rate of the graphite powder was 140%, and the hydrogen storage amount was increased by 750% (0.2 wt% → 1.7 wt%) (Table 1 and Table 2).

Example  4.

10 g of natural graphite was placed in a 500 ml ball mill reaction vessel and filled with 250 ml of alumina balls having a diameter of 10 mm, and then purged with N ₂ in the vessel. The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present example, before and after the treatment, the volume increase rate of the graphite powder was 270%, and the hydrogen storage amount was increased by 1650% (0.2 wt% → 3.5 wt%) (Table 1 and Table 2).

Example  5.

10 g of natural graphite was placed in a 500 ml ball mill reaction vessel and filled with 250 ml of alumina balls having a diameter of 10 mm, and then purged with N ₂ in the vessel. The reaction vessel was fixed at 1500 rpm and milled for about 120 minutes, at which time the temperature was 25 ° C.

In the present Example, before and after the treatment, the volume increase rate of the graphite powder was 300%, and the hydrogen storage amount was increased by 1500% (0.2 wt% → 3.2 wt%) (Table 1 and Table 2).

Example  6.

10 g of natural graphite was placed in a ball mill reaction vessel having a volume of 500 ml, and filled with 250 ml of alumina balls having a diameter of 10 mm, and then purged with O ₂ . The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present Example, before and after the treatment, the volume increase rate of the graphite powder was 290%, and the hydrogen storage amount was increased by 2150% (0.2 wt% → 4.5 wt%) (Table 1 and Table 2).

Example  7.

10 g of natural graphite was placed in a 500 ml ball mill reaction vessel and filled with 250 ml of alumina balls having a diameter of 10 mm, and then purged with NH ₃ . The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present Example, before and after the treatment, the volume increase rate of the graphite powder was 290%, and the hydrogen storage amount was increased by 1950% (0.2 wt% → 4.0 wt%) (Table 1 and Table 2).

Example  8.

10 g of natural graphite was placed in a ball mill reaction vessel having a volume of 500 ml, filled with steel balls having a diameter of 10 mm up to 250 ml, and the inside of the vessel was purged with N ₂ . The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present example, before and after the treatment, the volume increase rate of the graphite powder was 270%, and the hydrogen storage amount was increased by 1700% (0.2 wt% → 3.6 wt%) (Table 1 and Table 2).

Example  9.

10 g of natural graphite was placed in a 500 ml ball mill reaction vessel, filled with 10 ml of zirconium silicate balls with a diameter of 250 mm, and the vessel was purged with N ₂ . The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present example, before and after the treatment, the volume increase rate of the graphite powder was 270%, and the hydrogen storage amount was increased by 1600% (0.2 wt% → 3.4 wt%) (Table 1 and Table 2).

Example  10.

10 g of natural graphite was placed in a 500 ml volume ball mill reaction vessel, filled with 250 ml of kaolin balls having a diameter of 10 mm, and the vessel was purged with N ₂ . The reaction vessel was fixed at 800 rpm and milled for about 60 minutes, at which time the temperature was 25 ° C.

In the present example, before and after the treatment, the volume increase rate of the graphite powder was 270%, and the hydrogen storage amount was increased by 1650% (0.2 wt% → 3.5 wt%) (Table 1 and Table 2).

Comparative example  One.

10 g of natural graphite was placed in a 500 ml volume ball mill reaction vessel, filled with 250 ml of kaolin balls having a diameter of 10 mm, and the vessel was purged with N ₂ . The reaction vessel was fixed at 800 rpm and milled for about 600 minutes, at which time the temperature was 25 ° C.

In this comparative example, before and after the treatment, the volume increase rate of the graphite powder was 10%, and since the pores were not formed due to the complete peeling of the graphite sheet, the hydrogen storage amount did not increase (Table 1 and Table 2).

Comparative example  2.

10 g of natural graphite was placed in a ball mill reaction vessel having a volume of 500 ml, 10 ml of kaolin balls with a diameter of 250 ml were filled, and the inside of the vessel was purged with N ₂ . The reaction vessel was fixed at 10 rpm and milled for about 600 minutes, at which time the temperature was 25 ° C.

In the comparative example, the volume increase rate of the graphite powder was less than 5% and the hydrogen storage amount did not increase (Table 1, Table 2).

Having described specific parts of the present invention in detail, it will be apparent to those of ordinary skill in the art that such specific descriptions are merely preferred embodiments, and thus the scope of the present invention is not limited thereto. will be. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

1 is a conceptual diagram of a ball mill.

2 is a detailed view of the ball mill reaction vessel.

Claims (17)

(a) injecting graphite and balls into the sealed reaction vessel; (b) purging an active gas into the reaction vessel into which graphite and balls are introduced in step (a); (c) milling the reaction vessel in which the active gas is purged by the step (b) at 800 rpm for 60 minutes; manufacturing method of a hydrogen storage material containing graphite powder. delete The method of claim 1, The active gas introduced into the reaction vessel in the step (b) is a method for producing a hydrogen storage material containing graphite powder, characterized in that the oxygen or ammonia. The method of claim 1, The graphite is a method of producing a hydrogen storage material containing graphite powder, characterized in that the powder (flakes), flakes (flakes) or plate (plates) form. delete The method of claim 1, The ball is a method for producing a hydrogen storage material containing graphite powder, characterized in that the alumina (alumina), iron (steel), kaolin (kaolin), zirconium (zirconium) or silicate (silicate) material. The method of claim 1, The volume ratio (v / v) of the ball / graphite is a method for producing a hydrogen storage material containing graphite powder, characterized in that 0.5 to 5. delete delete The method of claim 1, The ball milling method for producing a hydrogen storage material containing graphite powder, characterized in that the treatment at a temperature of room temperature to 100 ℃. delete delete delete delete delete delete delete

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