JP5633068B2 - Hydrogen generation catalyst and hydrogen generation method - Google Patents

Description

  The present invention relates to a hydrogen generation catalyst and a hydrogen generation method.

  Hydrogen gas supplied to the fuel cell can be generated by electrolyzing water; reacting metal with acid; reacting water with metal hydride; reforming methyl alcohol or natural gas with steam Methods: Various methods are known, such as a method of releasing hydrogen from a hydrogen storage material such as a hydrogen storage alloy, activated carbon, carbon nanotube, or lithium-nitrogen material. However, these methods have drawbacks such as requiring a large amount of energy to generate hydrogen, a small amount of hydrogen generation with respect to the raw materials used, and a large-scale facility. For this reason, these methods can be used for production of hydrogen on a factory scale or generation of hydrogen to the extent that it can be used in laboratories. However, the required amount of hydrogen fuel can be continuously supplied and the size can be reduced. It is not suitable as a hydrogen supply method for required fuel cells for automobiles; portable fuel cells for mobile phones, personal computers, and the like.

On the other hand, metal hydrides such as LiAlH ₄ and NaBH ₄ are used in laboratories as hydrogenation reagents, but when they come into contact with water, a large amount of hydrogen is temporarily generated to cause an explosive phenomenon. It must be handled with care and is also unsuitable as a hydrogen source for the fuel cell described above.

Tetrahydroborate such as NaBH ₄ (see Patent Documents 1 and 2 and Non-Patent Documents 1 and 2 below) and borane / ammonia represented by the chemical formula: NH ₃ BH ₃ (Patent Document 3 and Non-Patent Documents 3 and 3 below) 4), the method of releasing hydrogen using a hydrolysis reaction has also been reported. However, these methods have problems in terms of recovery and regeneration of a boric acid compound as a product.

Hydrazine (H ₂ NNH ₂ ) is a liquid at room temperature and has a high hydrogen content (12.5 wt%) and is considered a promising source of hydrogen, and it has been reported that it can be decomposed into nitrogen and hydrogen by catalytic reaction. ing. For example, Patent Document 4 below discloses a method of generating hydrogen by bringing hydrazine and its derivatives into contact with a metal having a hydrogen generation catalytic ability such as nickel, cobalt, iron, copper, palladium, platinum or the like. However, when these metal catalysts were examined for their ability to catalyze hydrogen generation in the decomposition reaction of hydrazine, a sufficient amount of hydrogen was not necessarily obtained (see Non-Patent Document 5 below).

  Patent Document 5 discloses a hydrogen production apparatus including a decomposer that uses ammonia or hydrazine as a hydrogen source, decomposes it into nitrogen and hydrogen, and supplies it to the fuel cell. However, Patent Document 5 does not specifically disclose a method for decomposing hydrazine to generate hydrogen.

  Patent Documents 6 and 7 disclose a method of generating hydrogen by bringing a catalyst in which rhodium is supported on a support containing alumina or silica and an aqueous hydrazine solution into contact with each other. However, in these methods, the hydrogen generation rate from hydrazine is low, and a sufficient amount of hydrogen generation is not obtained.

Japanese Patent Laid-Open No. 2001-19401 JP 2002-241102 A JP 2006-213563 A Japanese Patent Laid-Open No. 2004-244251 JP 2003-40602 A JP 2007-269514 A JP 2007-269529 A

S. C. Amendola et al., International Journal of Hydrogen Energy, 25 (2000), 969-975. Z. P. Li et al., Journal of Power Source, 126 (2004) 28-33. M. Chandra, Q. Xu, Journal of Power Sources 156 (2006) 190-194. Q. Xu, M. Chandra, Journal of Power Sources 163 (2006) 364-370. Sanjay Kumar Singh, Xin-Bo Zhang, Qiang Xu, J. Am. Chem. Soc., 131 (2009) 9894-9895.

  The present invention has been made in view of the above-described problems of the prior art, and its main purpose is to generate hydrogen with high selectivity and high efficiency and low cost in a hydrogen generation method utilizing a decomposition reaction of hydrazine. It is to provide a method that can be made to.

  The present inventor has intensively studied to achieve the above-described object. As a result, when hydrazine or its hydrate is used as a hydrogen generation source, by using a composite metal of iridium and nickel as a catalyst, the selection is very high compared to the case of using a conventionally known metal catalyst. It has been found that hydrogen can be generated efficiently and at low cost, and the present invention has been completed here.

That is, the present invention provides the following hydrogen generation catalyst and hydrogen generation method.
1. Hydrazine and its hydration comprising a composite metal of iridium and nickel obtained by adding a reducing agent to an aqueous solution containing an iridium compound, a nickel compound , and hexadecyltrimethylammonium bromide to reduce iridium ions and nickel ions A catalyst for hydrogen generation by a decomposition reaction of at least one compound selected from the group consisting of compounds.
2. Item 2. The hydrogen generation catalyst according to Item 1, wherein the composite metal of iridium and nickel is an alloy of iridium and nickel, an intermetallic compound, or a solid solution.
3. Item 3. The hydrogen generation catalyst according to Item 1 or 2, wherein the iridium content in the composite metal of iridium and nickel is in the range of 0.1 to 39 mol%.
4). 4. A hydrogen generation method, wherein the hydrogen generation catalyst according to any one of Items 1 to 3 is contacted with at least one compound selected from the group consisting of hydrazine and hydrates thereof.
5. A method for supplying hydrogen to a fuel cell, comprising supplying hydrogen generated by the method of item 4 above as a hydrogen source for the fuel cell.

  Hereinafter, the present invention will be specifically described.

In the hydrogen generation method of the present invention, at least one compound selected from the group consisting of hydrazine represented by the chemical formula: H ₂ NNH ₂ and hydrates thereof is used as the hydrogen generation source. Hydrazine (anhydride and monohydrate) is a known compound and is liquid at room temperature.

In general, a hydrazine-catalyzed decomposition reaction involves a hydrazine complete decomposition reaction in which hydrogen and nitrogen represented by the following formula (1) are generated, or a hydrazine partial decomposition reaction in which ammonia and nitrogen are represented by the formula (2). It is considered to be.

N ₂ H ₄ → N ₂ + 2H ₂ (1)
3N ₂ H ₄ → N ₂ + 4NH ₃ (2)

  Non-Patent Document 5 described above describes the decomposition reaction of hydrazine in the presence of a rhodium catalyst. When rhodium metal is used as a catalyst, the hydrazine complete decomposition reaction represented by the formula (1) is more effective. It is described that the hydrazine partial decomposition reaction represented by (2) proceeds preferentially to produce a large amount of ammonia. For other metal catalysts, when metals such as platinum, palladium, nickel, copper and iron are used as catalysts, the decomposition reaction of hydrazine does not proceed, and metals such as cobalt, ruthenium and iridium are used as catalysts. In this case, the complete decomposition reaction of hydrazine proceeds slightly, but the partial decomposition reaction mainly proceeds to produce a large amount of ammonia.

  Furthermore, according to the research of the present inventors, when the catalyst is a composite metal of iridium and copper, a composite metal of iridium and iron, a composite metal of iridium and cobalt, etc., the selectivity of the hydrogen generation reaction by complete decomposition is improved. It is clear that no improvement is observed.

  On the other hand, when the composite metal of iridium and nickel used in the present invention is used as a catalyst, the partial decomposition reaction in which ammonia is generated is suppressed, and the complete decomposition reaction in which hydrogen is generated selectively proceeds.

  Hereinafter, the composite metal catalyst of iridium and nickel used in the present invention and a hydrogen generation method using the catalyst will be specifically described.

Iridium / nickel composite metal catalyst The iridium / nickel composite metal catalyst used in the hydrogen generation method of the present invention is not a mixture of iridium and nickel, but a composite metal in which iridium and nickel are closely related to each other. is there. Specific examples of such composite metals include alloys, intermetallic compounds, and solid solutions.

  As described above, when iridium alone is used as a catalyst, a partial decomposition reaction mainly proceeds to produce a large amount of ammonia. When nickel metal is used alone as a catalyst, the decomposition reaction of hydrazine is Does not progress. Further, the mere physical mixture of iridium and nickel metal shows no improvement in the selectivity of the complete decomposition reaction of hydrazine as compared with the case of iridium alone.

  On the other hand, when a metal catalyst in which iridium and nickel are combined is used, surprisingly, the complete decomposition reaction of hydrazine represented by the above formula (1) proceeds with good selectivity and is very efficient. Hydrogen can be generated.

  Regarding the ratio of iridium and nickel in the composite metal of iridium and nickel, the ratio of Ir is within the range of about 0.1 to 39 mol% based on the total number of moles of Ir and Ni, compared with the case of Ir alone. The selectivity for the hydrogen generation reaction due to the complete decomposition reaction of hydrazine is enhanced. Particularly, the complete decomposition reaction of hydrazine proceeds at a very high selectivity in the range where the ratio of Ir is about 1 to 25 mol%. Hydrogen can be generated.

There is no particular limitation on the method for producing the composite metal catalyst of iridium and nickel. For example, by adding a reducing agent to an aqueous solution containing an iridium compound and a nickel compound, the iridium ion and nickel ion are reduced and metallized. As a result, the target composite metal of iridium and nickel can be obtained. In addition, after reducing a iridium ion by adding a reducing agent to an aqueous solution containing an iridium compound, the nickel compound is further reduced by adding a nickel compound, or a reducing agent is added to an aqueous solution containing the nickel compound to reduce nickel ions. Then, a method of adding an iridium compound for reduction and the like can also be employed. In particular, according to a method in which a reducing agent is added to an aqueous solution containing an iridium compound and a nickel compound to reduce iridium ions and nickel ions, a metal catalyst having excellent uniformity can be obtained. The iridium compound and nickel compound used in these methods are not particularly limited, but may be any compound that is soluble in a solvent. For example, metal salts such as iridium or nickel chloride, nitrate, sulfate, and various metal complexes Can be used.

  The reducing agent used for reducing these iridium compounds and nickel compounds is not particularly limited as long as it can reduce iridium compounds and nickel compounds, such as sodium tetrahydroborate and hydrazine itself. Available.

  The size of the composite metal of iridium and nickel is not particularly limited. For example, a composite metal in an ultrafine particle state having a particle size of about 1 to 100 nm is advantageous in that it has high activity. In this case, the particle diameter of the composite metal is a value measured by an electron microscope.

  The iridium and nickel composite metal may be further composited with other metals within a range that does not adversely affect the catalytic activity.

  The composite metal of iridium and nickel may be used as a supported catalyst supported on a support such as silica, alumina, zirconia, or activated carbon. The method for producing such a supported catalyst is not particularly limited. For example, it can be obtained by reducing the iridium compound and the nickel compound in a state where the carrier is dispersed in a solution containing the iridium compound and the nickel compound. Can do. The amount supported is not particularly limited. For example, the amount of the composite metal is preferably about 0.1 to 20% by weight based on the total amount of the composite metal of iridium and nickel and the carrier, More preferably, it is about 10 to 10 weight%, More preferably, it is about 1 to 5 weight%.

Hydrogen Generation Method In the hydrogen generation method of the present invention, at least one compound selected from the group consisting of hydrazine and hydrates thereof is used as the hydrogen generation source. There is no limitation in particular about the kind of hydrazine and its hydrate, What is generally marketed can be used as it is. Further, other components may be included at the same time as long as there is no adverse effect on the hydrogen generation.

Among these compounds, when anhydrous hydrazine (H ₂ NNH ₂ ) is used as a raw material, hydrogen generation efficiency is high because 12.5% by weight of hydrogen is generated with respect to hydrazine. Because there is a problem with safety. On the other hand, in the case of hydrazine monohydrate _{(H 2 NNH 2 · H 2} O) and hydrogen source, since 8 wt% of hydrogen is generated for hydrazine monohydrate, and the raw material anhydride The hydrogen generation efficiency is somewhat inferior to that in the case where it is performed. However, the hydrogen generation efficiency is still high, and the safety is further improved. For this reason, in consideration of safety, hydrazine monohydrate or an aqueous solution obtained by further diluting it may be used. In the present invention, it is preferable to use an aqueous solution having a hydrazine concentration of about 40 to 64% by weight, considering both safety and hydrogen generation efficiency.

In the hydrogen generation method of the present invention, at least one compound selected from the group consisting of hydrazine and hydrates thereof is used as a hydrogen generation source, and this is brought into contact with the above-described catalyst made of a composite metal of iridium and nickel. Good. A specific method is not particularly limited, and for example, a method of adding hydrazine and a catalyst in a reaction vessel and mixing them can be employed. Moreover, the method of introduce | transducing hydrazine aqueous solution to the reactor filled with the catalyst, and letting it pass a catalyst layer is also employable.

  The amount of the catalyst comprising the composite metal of iridium and nickel is not particularly limited, and the composite metal of iridium and nickel is used with respect to 1 mol of at least one compound selected from the group consisting of hydrazine and hydrates thereof. Can be selected from a wide range of about 0.0001 to 10 mol. In particular, considering the balance of reaction rate, catalyst cost, and the like, for example, the amount of the composite metal is 0.01 to 0.00 with respect to 1 mol of at least one compound selected from the group consisting of hydrazine and hydrates thereof. It is preferably about 5 moles. In the method of passing through the catalyst layer, the catalyst amount of the catalyst layer may be determined in consideration of the flow rate of hydrazine or its hydrate solution and the contact time.

  The reaction temperature of the hydrogen generation reaction is not particularly limited, but is preferably about 0 ° C to 80 ° C, and more preferably about 10 to 50 ° C.

  There is no limitation in particular about the pressure and atmosphere in the reaction system at the time of reaction, and it can select suitably.

Method for Utilizing Generated Hydrogen According to the method of the present invention, hydrogen generation reaction by decomposition of hydrazine proceeds with good selectivity, and hydrogen can be generated efficiently.

  The generated hydrogen can be directly supplied to the fuel cell as fuel for the fuel cell, for example. In particular, the hydrogen generation method of the present invention can generate hydrogen at a temperature near room temperature, and can control the hydrogen generation rate, generation amount, etc., so that it is a fuel cell for automobiles; This method is highly useful as a hydrogen supply method for computers and other portable fuel cells.

  The generated hydrogen can be collected and stored in a container filled with a hydrogen storage alloy, for example. It is also possible to control the internal pressure of the generated hydrogen by using a hydrogen storage alloy and adjusting the temperature according to the equilibrium pressure-temperature relationship.

  According to the hydrogen generation method of the present invention, hydrogen gas can be efficiently generated under controllable conditions without heating to a high temperature.

  Moreover, since the catalyst for hydrogen generation of the present invention exhibits high activity even when the iridium content is low, it can be a low-cost catalyst.

  The hydrogen gas generated by the method of the present invention is highly useful as a fuel for, for example, a fuel cell for automobiles and a portable fuel cell.

The transmission electron microscope (TEM) image of the catalyst particle obtained in Example 1. FIG. The high angle scattering dark field (scanning transmission electron microscope) (HAADF-STEM) image and EDS spectrum of the catalyst particle obtained in Example 1. The graph which shows the relationship between the molar ratio of the discharge gas with respect to the hydrazine monohydrate measured in Example 1, the comparative example 1, the comparative example 2, and the comparative example 3, and reaction time. The graph which shows the relationship between the molar ratio of the discharge gas with respect to the hydrazine monohydrate measured in Examples 1-3, and reaction time. The graph which shows the relationship between Ir content (mol%) in a nickel-iridium nanoparticle catalyst, and the selectivity of hydrogen production reaction.

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

Example 1
To a 30 ml two-necked flask, add NiCl ₂ · 6H ₂ O (0.045 g), H ₂ IrCl ₆ (0.004 g), hexadecyltrimethylammonium bromide (CTAB, 95%) (0.100 g), and water ( 2.5 mL), ultrasonically stirred for 5 minutes, heated at 50 ° C. for 5 minutes, and then returned to room temperature. Then, NaBH ₄ (0.020 g) aqueous solution (1.5 mL) was added and the reaction vessel was shaken vigorously for 5 minutes. Thus, a Ni _0.95 Ir _0.05 nanoparticle catalyst was formed.

A transmission electron microscope (TEM) image of the obtained Ni _0.95 Ir _0.05 nanoparticle catalyst is shown in FIG. FIG.
As is clear from the above, the catalyst was ultrafine particles having a particle size of about 5 nm.

FIG. 2 shows a high-angle scattering dark field (scanning transmission electron microscope) (HAADF-STEM) image of the Ni _0.95 Ir _0.05 nanoparticle catalyst, and the Ir and Ni EDS spectral intensities measured at the points in the figure. Shown in the upper right part. As apparent from the EDS spectrum shown in FIG. 2, Ir and Ni are present at the same position, and are not present as individual metal particles, but are in an alloyed state coexisting at the atomic level. I can confirm.

Then, the two-necked flask hydrazine monohydrate in a syringe _{(H 2 NNH 2 · H 2} O, 99%) (0.1mL, 1.97 mmol) were charged, and stirring was continued at room temperature. The released gas was passed through a trap containing 1.0 M hydrochloric acid to absorb ammonia, and then only hydrogen and nitrogen were introduced into the gas burette, and the released amount was measured. 2 ml 5 minutes after the start of stirring, 4.3 ml after 10 minutes, 8.5 ml after 20 minutes, 22 ml after 50 minutes, 42 ml after 100 minutes, 60 ml after 150 minutes, 105 ml after 300 minutes, 130 ml after 405 minutes, 144 ml after 450 minutes After 540 minutes, 146 ml outgassing was observed.

  FIG. 3 is a graph showing the relationship between the molar ratio of the released gas to the hydrazine monohydrate used as a raw material and the reaction time. Moreover, in FIG. 3, the result of the comparative example 1, the comparative example 2, and the comparative example 3 mentioned later is also shown.

  As a result of mass spectrometry (MS), it was confirmed that the released gas was hydrogen and nitrogen. The amount of gas released was 3 times the mol of hydrazine used as a raw material. This gas release amount corresponds to the case where the selectivity of the hydrogen generation reaction by the complete decomposition of hydrazine is 100%.

  In addition, it was confirmed that the gas generated by the above-described method was directly introduced into the solid polymer fuel cell to operate the fuel cell.

Comparative Example 1
Place NiCl ₂ · 6H ₂ O (0.047 g), hexadecyltrimethylammonium bromide (CTAB, 95%) (0.105 g), and water (2.5 mL) into a 30 ml two-necked flask for more than 5 minutes. After stirring by sonication, an aqueous solution of NaBH ₄ (0.020 g) (1.5 mL) was added, and the reaction vessel was shaken vigorously for 2 minutes to form a Ni nanoparticle catalyst.

The two-necked flask hydrazine monohydrate in a syringe _{(H 2 NNH 2 · H 2} O, 99%) (0.1 mL, 1.97 mmol) were charged, was stirred for 120 minutes at room temperature, outgassing observed It was.

Comparative Example 2
IrCl ₃ (0.058 g), hexadecyltrimethylammonium bromide (CTAB, 95%) (0.105 g), and water (2.5 mL) were placed in a 30-ml two-necked flask and subjected to ultrasonic stirring for 5 minutes. NaBH ₄ (0.020 g) aqueous solution (1.5 mL) was added, and the reaction vessel was vigorously shaken for 2 minutes to form an Ir nanoparticle catalyst.

The two-necked flask hydrazine monohydrate in a syringe _{(H 2 NNH 2 · H 2} O, 99%) (0.1 mL, 1.97 mmol) were charged, and stirring was continued at room temperature. The released gas was passed through a trap containing 1.0 M hydrochloric acid to absorb ammonia, and then only hydrogen and nitrogen were introduced into the gas burette, and the released amount was measured. 4 ml after 1 minute of stirring, 7 ml after 2 minutes, 11 ml after 4 minutes, 14 ml after 6 minutes, 17.5 ml after 10 minutes, 21.5 ml after 20 minutes, 23 ml after 30 minutes, 23.5 ml after 40 minutes, 50 minutes Later, 24 ml outgassing was observed after 60 min and 60 min.

  As a result of mass spectrometry (MS), it was confirmed that the released gas was hydrogen and nitrogen. The amount of gas released was 0.5 times mol of hydrazine used as a raw material. This gas release amount corresponds to a case where the selectivity of the hydrogen generation reaction by complete decomposition of hydrazine is 7%.

Comparative Example 3
Ni nanoparticles and Ir nanoparticles were formed by the same method as in Comparative Example 1 and Comparative Example 2, respectively, and dried. Ni nanoparticles 11.2 mg and Ir nanoparticles 2 mg obtained by this method were placed in a 30 ml two-necked flask, stirred and dispersed with water (4 mL).

The two-necked flask hydrazine monohydrate in a syringe _{(H 2 NNH 2 · H 2} O, 99%) (0.1 mL, 1.97 mmol) were charged, and stirring was continued at room temperature. The released gas was passed through a trap containing 1.0 M hydrochloric acid to absorb ammonia, and then only hydrogen and nitrogen were introduced into the gas burette, and the released amount was measured. 10 minutes after starting stirring, 4 ml after 30 minutes, 6.5 ml after 60 minutes, 10 ml after 120 minutes, 13 ml after 180 minutes, 16 ml after 240 minutes, 20 ml after 330 minutes, 22 ml after 360 minutes, 23 ml after 390 minutes, 480 After 23 minutes, an outgassing of 23 ml was observed.

  As a result of mass spectrometry (MS), it was confirmed that the released gas was hydrogen and nitrogen. The amount of gas released was 0.5 times mol of hydrazine used as a raw material. This gas release amount corresponds to a case where the selectivity of the hydrogen generation reaction by complete decomposition of hydrazine is 7%.

  As is clear from this result, when the mixture of Ni nanoparticles and Ir nanoparticles is used as a catalyst, the selectivity of the hydrogen generation reaction is the same as when using the catalyst only from Ir nanoparticles in Comparative Example 2. The selectivity of hydrazine complete decomposition and hydrogen generation reaction was not observed.

Example 2
To a 30 ml two-necked flask, add NiCl ₂ · 6H ₂ O (0.043 g), H ₂ IrCl ₆ (0.008 g), hexadecyltrimethylammonium bromide (CTAB, 95%) (0.100 g), and water ( 2.5 mL), ultrasonically stirred for 5 minutes, heated at 50 ° C for 5 minutes, and then returned to room temperature. NaBH ₄ (0.020 g)
An aqueous solution (1.5 mL) was added and the reaction vessel was vigorously shaken for 5 minutes to form a Ni _0.90 Ir _0.10 nanoparticle catalyst.

Next, hydrazine monohydrate (H ₂ NNH 2H ₂ O, 99%) (0.1%) was added to the _two -necked flask with a syringe.
mL, 1.97 mmol) was added and stirring was continued at room temperature. The released gas was passed through a trap containing 1.0 M hydrochloric acid to absorb ammonia, and then only hydrogen and nitrogen were introduced into the gas burette, and the released amount was measured. 3 ml after 5 minutes from the start of stirring, 7 ml after 10 minutes, 13 ml after 20 minutes, 29.5 ml after 40 minutes, 45 ml after 60 minutes, 62 ml after 80 minutes, 90 ml after 120 minutes, 119 ml after 180 minutes, 130 ml after 210 minutes, 240 139 ml after 1 minute, 1 after 270 minutes
An outgassing of 146 ml was observed after 45 ml and 300 minutes.

  FIG. 4 is a graph showing the relationship between the molar ratio of the released gas to the hydrazine monohydrate used as a raw material and the reaction time. FIG. 4 also shows the results of Example 1 and the results of Example 3 described later.

  As a result of mass spectrometry (MS), it was confirmed that the released gas was hydrogen and nitrogen. The amount of gas released was 3.0 times the mol of hydrazine used as a raw material. This gas release amount corresponds to the case where the selectivity of the hydrogen generation reaction by the complete decomposition of hydrazine is 100%.

  In addition, it was confirmed that the gas generated by the above-described method was directly introduced into the solid polymer fuel cell to operate the fuel cell.

Example 3
A 30 ml two-necked flask was charged with NiCl ₂ · 6H ₂ O (0.036 g), H ₂ IrCl ₆ (0.020 g), hexadecyltrimethylammonium bromide (CTAB, 95%) (0.100 g), and water (2.5 After 5 minutes of ultrasonic agitation, heat at 50 ° C. for 5 minutes and then return to room temperature. Add NaBH ₄ (0.020 g) aqueous solution (1.5 mL) and shake the reaction vessel vigorously for 5 minutes. A Ni _0.75 Ir _0.25 nanoparticle catalyst was formed.

Next, hydrazine monohydrate (H ₂ NNH 2H ₂ O, 99%) (0.1%) was added to the _two -necked flask with a syringe.
mL, 1.97 mmol) was added and stirring was continued at room temperature. The released gas was passed through a trap containing 1.0 M hydrochloric acid to absorb ammonia, and then only hydrogen and nitrogen were introduced into the gas burette, and the released amount was measured. 6 ml after starting 5 minutes, 12 ml after 10 minutes, 25 ml after 20 minutes, 47 ml after 40 minutes, 66 ml after 60 minutes, 81.5 ml after 80 minutes, 94 ml after 100 minutes, 105 ml after 120 minutes, 116 ml after 150 minutes, 180 ml Outgassing of 123 ml after minutes, 126 ml after 210 minutes and 126 ml after 270 minutes was observed.

  As a result of mass spectrometry (MS), it was confirmed that the released gas was hydrogen and nitrogen. The amount of gas released was 2.6 moles compared to hydrazine used as a raw material. This gas release amount corresponds to the case where the selectivity of the hydrogen generation reaction by complete decomposition of hydrazine is 85%.

  In addition, it was confirmed that the gas generated by the above-described method was directly introduced into the solid polymer fuel cell to operate the fuel cell.

Example 4
In the method for producing nickel-iridium nanoparticles of Example 1, the amounts of NiCl ₂ · 6H ₂ O and H ₂ IrCl ₆ were changed to obtain Ni _0.99 Ir _0.01 nanoparticle catalyst, Ni _0.60 Ir _0.40 nanoparticle catalyst, Ni _0.50 Ir _0.50 nanoparticle catalyst and Ni _0.25 Ir _0.75 nanoparticle catalyst were prepared. Using each catalyst, an emission gas measurement experiment using hydrazine monohydrate as a raw material was performed in the same manner as in Example 1. From the amount of hydrogen and nitrogen released, the hydrogen generation reaction by the complete decomposition reaction of hydrazine was performed. The selectivity was determined.

  FIG. 5 shows the Ir content (mol%) in the nickel-iridium nanoparticle catalyst determined based on the results of Example 4 and the results of Examples 1 to 3, Comparative Example 1 and Comparative Example 2, and the hydrogen generation reaction. It is a graph which shows the relationship with a selection rate.

  From FIG. 5, it can be confirmed that the selectivity for the hydrogen generation reaction by the complete decomposition reaction of hydrazine is improved when the ratio of Ir to the total number of moles of Ir and Ni is 0.1 to 39 mol%.

Claims (5)

Hydrazine and its hydration comprising a composite metal of iridium and nickel obtained by adding a reducing agent to an aqueous solution containing an iridium compound, a nickel compound , and hexadecyltrimethylammonium bromide to reduce iridium ions and nickel ions A catalyst for hydrogen generation by a decomposition reaction of at least one compound selected from the group consisting of compounds. The catalyst for hydrogen generation according to claim 1, wherein the composite metal of iridium and nickel is an alloy of iridium and nickel, an intermetallic compound, or a solid solution. The catalyst for hydrogen generation according to claim 1 or 2, wherein the iridium content in the composite metal of iridium and nickel is in the range of 0.1 to 39 mol%. A method for generating hydrogen, comprising contacting the hydrogen generating catalyst according to any one of claims 1 to 3 with at least one compound selected from the group consisting of hydrazine and hydrates thereof. A method for supplying hydrogen to a fuel cell, comprising supplying hydrogen generated by the method of claim 4 as a hydrogen source for the fuel cell.

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