JP6523769B2 - Hydrogen molecule storage material and hydrogen generation method thereof - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a hydrogen molecule storage material and a hydrogen generation method thereof.

  At present, petroleum-derived fuels such as gasoline are used as energy sources for driving automobiles.

  However, such petroleum-derived fuel contains various impurities in addition to the main component hydrocarbon, and when such fuel is used, the exhaust gas from the internal combustion engine is generated by combustion of the hydrocarbon. In addition to carbon dioxide, nitrogen oxides, particulate matter, etc. are also included, causing problems in terms of environmental pollution and global warming. For this reason, a clean power source that can suppress the occurrence of these is required.

  It has been proposed to use hydrogen as a fuel as a clean energy source for solving such a situation. Hydrogen is a clean energy source in that it burns only to generate water and does not generate harmful substances that cause environmental pollution and global warming as described above.

  In view of such advantages, in recent years, use of hydrogen as an energy source has been proposed in many cases. For example, development of a hydrogen fuel cell powered by a fuel cell is actively promoted. ing.

  However, hydrogen is gaseous at normal temperature and pressure, has a large volume, and may be compressed under pressure for storage, but still has a large volume for storage. Automobiles are composed of various components such as electric systems, cooling systems, control systems, etc., in addition to the constitution for driving an engine, and are arranged in a complex and elaborate manner, and hydrogen-powered cars, for example, fuel cells In an automobile that uses the “fuel cell automobile” for the sake of simplicity, if the volume occupied by the hydrogen supply means, which is the energy source of the engine, is large, it may cause a problem in the functional aspect of the automobile. In addition, the design of the vehicle is greatly restricted, and how to supply hydrogen is a major issue.

Then, as a result of repeating earnest examinations in order to solve the said subject, the present inventors bake a cation for 2 hours in hydrogen atmosphere at the temperature of 500-1500 degreeC (for example, 1300 degreeC) like patent document 1. hydrogen substituted mayenite which is to form ^{_{(Ca 24 a 128 O 64 4+}} · 4H -) and a method for producing hydrogen by reacting water and the hydrogen substituted mayenite ^- in ^{_{(Ca 24 a 128 O 64 4+}} · 4H) A method for producing hydrogen was completed by reacting conductive mayenite (Ca ₂₄ A ₁₂₈ O ₆₄ ^{4 +} · ⁴ e ⁻ ) obtained by irradiation with ultraviolet light with water.

  If hydrogen can be stored in such hydrogen-substituted mayenite or conductive mayenite, the volume for the hydrogen supply means can be made smaller than when hydrogen itself is to be stored.

JP 2014-136661 A

  However, in the invention described in Patent Document 1 described above, it has been necessary to perform treatment under severe conditions of treatment under a hydrogen atmosphere under high temperature conditions of 500 to 1500 ° C. to produce hydrogen-substituted mayenite. In the invention described in Patent Document 1, although hydrogen can be stored in hydrogen-substituted mayenite or conductive mayenite as a hydrogen supply means, hydrogen-substituted mayenite or conductive mayenite can be used to release hydrogen therefrom. Had to react with water. That is, in the invention described in the above-mentioned patent documents 1, means for storing water were needed separately.

  Further, in the invention described in Patent Document 1 described above, in order to cause the various mayenites after releasing hydrogen to absorb hydrogen again, treatment is performed again under a hydrogen atmosphere at a temperature condition of 500 to 1500 ° C. It must be done, and re-storage of hydrogen was not easy.

  Therefore, according to the present invention, hydrogen can be released by heating in a relatively low temperature range slightly higher than normal temperature, and a large volume is not required, and furthermore, hydrogen resorption after hydrogen release is also easy. It is an object of the present invention to provide a hydrogen molecule storage material capable of

As a result of intensive investigations by the present inventors in order to solve the above-mentioned problems, the inventors have completed the following invention. That is,
The present invention relates to a hydrogen molecule storage material formed by storing hydrogen molecules in mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ).

  The present invention also relates to a hydrogen generation method for heating the above-mentioned hydrogen molecule storage material to 40 ° C. or higher to release hydrogen molecules from the hydrogen molecule storage material.

  In the above method, the heating temperature of the hydrogen molecule storage material is preferably 90 ° C. or less.

  In the above method, it is preferable to heat the hydrogen molecule storage material with a heat medium.

  In the above method, the heat medium is preferably water, air or an inert gas.

Further, the present invention relates to a method of re-occluding hydrogen by firing the above-mentioned mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ) after generating hydrogen molecules in a hydrogen atmosphere at 400 to 1350 ° C.

The hydrogen molecule storage material of the present invention is one obtained by storing hydrogen molecules in mayenite (Ca ₂₄ Al ₂₈ O ₆₄ ), and is a hydrogen-substituted mayenite or conductive mayenite described in JP-A-2014-136661. Differently, hydrogen can be released only by heating at about 40 to 90 ° C. without reaction with water. In addition, after releasing the hydrogen, in some cases, after drying the mayenite, it is possible to re-occlude the hydrogen by baking in a hydrogen-containing gas atmosphere.

It is a graph which shows the result of having performed solid-state NMR measurement about mayenite of a hydrogen molecule storage material. It is the schematic explaining the apparatus used for the measurement of the hydrogen generation amount from a hydrogen molecule storage material in the Example and comparative example of this invention. It is a graph which shows the result of having measured the hydrogen gas generation total amount in time progress using a mass flow meter of integration type in Example 1 and Example 2.

  Hereinafter, the hydrogen molecule storage material and the hydrogen generation method according to the present invention will be described in detail.

The hydrogen molecule storage material according to the present invention is formed by storing hydrogen molecules in mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ).

The method for producing mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ) used for the hydrogen molecule storage material according to the present invention is not particularly limited, and for example, as described below, a cation of aluminum powder and calcium hydroxide as raw materials It may be manufactured from a manufacturing process including a manufacturing process and a process of converting to mayenite. Alternatively, mayenite can also be produced by adding aluminum oxide to calcium oxide.
(Katoito manufacturing process)
The katoite [Katoite: Ca ₃ Al ₂ (OH) ₁₂ ] is formed by stirring aluminum powder and calcium hydroxide in an aqueous medium.

  It is preferable to use ion exchanged water as the aqueous medium.

  The mixing ratio of the aluminum powder and calcium hydroxide is about 2 to 3 of aluminum to 1 of calcium hydroxide in weight ratio, and the addition ratio of the aqueous medium is about 10 times or less. There are no particular limitations on the temperature conditions, pressure conditions, atmosphere conditions, and the like at the time of stirring, and it may be performed at normal temperature, normal pressure, or in an air atmosphere. Since hydrogen is generated by the reaction, the reaction time may be performed until generation of hydrogen gas is not observed.

Stirring produces katoite [Katoite: Ca ₃ Al ₂ (OH) ₁₂ ] and hydrogen (H ₂ ).

  After completion of the reaction, the resulting katoite precipitates, and this is filtered to collect the solid content. The solid obtained is subjected to a drying treatment, whereby a cation is obtained. The drying process is carried out at a temperature condition of 50 ° C. to 90 ° C., and the atmosphere condition at that time is not particularly limited, and is sufficient in air. The pressure is also not particularly limited, and may be normal pressure. The drying time may also be determined appropriately.

(Conversion process to mayenite)
Mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ) is obtained by subjecting the dried cutite obtained as described above to calcination.

  As described below, a hydrogen molecule storage material can be obtained by storing hydrogen molecules in the mayenite, but if the specific surface area of the mayenite increases, the amount of adsorbed hydrogen molecules adsorbed on the surface of the mayenite also increases. . The specific surface area of mayenite can be controlled by controlling the firing temperature of this step. From these points, the firing temperature of this step is controlled to a range of 300 to 500 ° C.

  Further, the atmospheric conditions and pressure conditions in this step are not particularly limited. For example, the atmospheric conditions may be under air and the pressure conditions may be normal pressure.

(Hydrogen storage process of mayenite)
A hydrogen molecule storage material obtained by storing hydrogen molecules in mayenite can be obtained by storing the hydrogen molecules in the mayenite obtained in the above-described process.

  In the hydrogen molecule storage step of this step, hydrogen can be stored even if the treatment temperature is less than 400 ° C. However, the treatment time becomes long and the efficiency is not good, so 400 ° C. or more is preferable. In addition, when the processing temperature exceeds 1350 ° C., energy is too much to be realistic. Therefore, the temperature for the hydrogen molecule storage step is preferably in the range of 400 to 1350 ° C.

  The hydrogen molecule storage step of this step is performed in a hydrogen-containing gas atmosphere under normal pressure or pressurized conditions. Hydrogen-containing gas means inert gas or air containing 5 to 100% by volume of hydrogen molecules.

  Through the above steps, the hydrogen molecule storage material according to the present invention is obtained.

  The hydrogen molecule storage material according to the present invention is formed by storing mayenite with hydrogen molecules, and the specific surface area thereof is controlled by controlling the baking temperature to 300 to 500 ° C. in the above conversion process to mayenite. Has become large, and a large amount of hydrogen molecules can be adsorbed on the surface. In this regard, in the conventional Japanese Patent Application Laid-Open No. 2014-136661, hydrogen-substituted mayenite is produced in a single step at a high temperature of 500 to 1500 ° C. without temperature control, and its surface is suitable for adsorption of hydrogen molecules. It is not suitable for the release of hydrogen only by heating, such as the hydrogen adsorbent according to the present invention as described below.

  Next, a hydrogen generation method using this hydrogen molecule storage material will be described.

(Hydrogen generation process)
The hydrogen molecule storage material of the present invention does not release hydrogen molecules under conditions of normal pressure and normal temperature, specifically around 25 ° C.

  When hydrogen is to be released from the hydrogen molecule storage material of the present invention, hydrogen is released by heating the hydrogen molecule storage material to 40 ° C. or higher. If the amount is less than 40 ° C., hydrogen will be released if the amount is small, but the rate of hydrogen release is slow and the efficiency is not good. Therefore, when hydrogen is intentionally released when hydrogen is desired, the temperature is raised to 40 ° C. or higher.

  The upper limit value of the heating condition is not particularly limited. For example, the heating temperature is maintained at a mild condition of 40 to 90 ° C., preferably 40 to 80 ° C., and more preferably 60 to 70 ° C. Thus, hydrogen can be released.

  When heating the above-mentioned hydrogen molecule storage material, it is preferable to use a heat carrier. More specifically, the heat medium may, for example, be water, air or an inert gas. The heat transfer method by the heat medium is performed either without being in direct contact with the hydrogen molecule storage material or in direct contact with the hydrogen molecule storage material. In the case of direct contact, this is done by keeping it with water, air and inert gas at a temperature of 40 to 90 ° C.

(Regeneration process)
Furthermore, the hydrogen molecule storage material according to the present invention can be regenerated by storing hydrogen molecules again after releasing the hydrogen molecules.

  When the hydrogen molecule storage material after hydrogen generation is performed by heating the above-mentioned hydrogen generation step with water, it may be heated by another method after drying mayenite (after water removal) In the hydrogen-containing gas atmosphere at a temperature of 400 to 1350 ° C. under normal pressure or under pressure, that is, hydrogen may be re-occluded by mayenite by firing under the same conditions as the hydrogen molecule storage step. .

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples.

Example 1
(Production of hydrogen molecule storage material)
200 mL of ion exchanged water was placed in a 1 L reactor (separable flask). Next, 9 g of aluminum powder (trade name: # 150, manufactured by Minalco) and 12 g of calcium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) were introduced into the reactor, and the whole was stirred. After the generation of hydrogen gas is completed (after visually confirming that the foaming phenomenon has been completed), the reaction solution in the reactor is filtered, and the solid collected by filtration is subjected to air at a temperature of 70 ° C. for 2 hours. Dried over. In this way I got a quart.

The cutite was calcined under air at a temperature of about 300 ° C. for 2 hours. By this firing, mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ) was obtained.

  The obtained mayenite was brought into contact with hydrogen under normal pressure and 1300 ° C. for 2 hours, and then allowed to cool to room temperature, thereby obtaining a hydrogen molecule storage material in which mayenite stores hydrogen molecules. . The result of having performed solid-state NMR measurement about the mayenite of a hydrogen molecule storage material in FIG. 1 is shown. The results of solid-state NMR measurement of hydrogen-substituted mayenite are also shown for comparison.

(Hydrogen generation by hydrogen molecule storage material)
0.45 g of the hydrogen molecule storage material obtained as described above was placed in a reactor having a volume of 50 mL, and heated to 60 ° C. by a heater. The amount of hydrogen generation at the time of heating was measured by a mass flow meter.

  FIG. 2 shows an outline of an apparatus used to measure this hydrogen generation amount. The hydrogen-containing gas generated from the reactor is passed through a dehumidifier filled with silica gel as a dehumidifying agent, where after the water is removed, it is passed through a mass flow meter, and the amount of generated hydrogen is measured in this mass flow meter .

  The hydrogen gas generation amount measured by the mass flow meter shown in FIG. 2 was 11 mL / g (hydrogen volume per weight of the hydrogen molecule storage material (g)).

  Further, the generated gas component was passed through a TCD (Thermal Conductivity Detector) type gas chromatograph (GC-8A manufactured by Shimadzu Corporation, a TCD (Thermal Conductivity Detector) detector), and it was identified as hydrogen here.

(Example 2)
In Example 2, when hydrogen was generated using the hydrogen molecule storage material obtained by the hydrogen molecule storage material manufacturing process of Example 1, heating was performed with water.

  Specifically, 0.45 g of the hydrogen molecule storage material obtained in the hydrogen molecule storage material production step of Example 1 and 10 mL of water are placed in a reactor having a volume of 50 mL, and Warm to 60 ° C.

  The measurement of the amount of generated hydrogen and the identification of being hydrogen were performed in the same manner as in Example 1.

  The amount of hydrogen gas generated was 44 mL / g.

  The result of having measured the hydrogen gas generation amount in time progress in Example 1 and Example 2 in FIG. 3 is shown.

(Example 3)
The same as Example 2 except that the water in the reactor was heated to 80 ° C.

  The amount of hydrogen gas generated was 44 mL / g.

(Comparative example 1)
In Comparative Example 1, 0.45 g of the hydrogen molecule storage material obtained in the hydrogen molecule storage material production step of Example 1 is placed in a reactor having a volume of 50 mL, but the room temperature (25 ° C.) is maintained without heating. It was made to do.

  The measurement of the amount of generated hydrogen and the identification of being hydrogen were performed in the same manner as in Example 1.

  However, the amount of gas generated was below the detection limit and could not be measured.

(Comparative example 2)
The same as Example 2 except that the water in the reactor was not heated but kept at room temperature (25 ° C.).

  The amount of hydrogen gas generated was below the detection limit and could not be measured.

  As clarified in Examples 1 to 3 above, the hydrogen molecule storage material of the present invention can release hydrogen only by heating, and in particular, by heating with water, a larger amount of hydrogen can be obtained. It has been found that hydrogen can be released. In addition, as shown in Comparative Examples 1 and 2, it was found that hydrogen was retained in the hydrogen molecule storage material without heating.

Claims (5)

A hydrogen generation method, wherein a hydrogen molecule storage material obtained by storing hydrogen molecules in mayenite (Ca ₂₄ Al ₂₈ O ₆₆ ) is heated to 40 ° C. to 90 ° C. to release hydrogen molecules from the hydrogen molecule storage material. The hydrogen generation method according to claim 1 , wherein the hydrogen molecule storage material is heated by a heat medium. The hydrogen generation method according to claim 2 , wherein the heat medium is water. The method for generating hydrogen according to claim 2 , wherein the heat transfer medium is air or an inert gas. Ma Ienaito after to generate hydrogen molecules by the method of any one of claims 1 to 4 and _{(Ca 24 Al 28 O 66)} , by calcination in a hydrogen atmosphere of 400-1,350 ° C., again absorb hydrogen How to

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