Hydrogen generation method

Abstract

The invention provides a hydrogen generation method comprising the step of bringing, in the presence of water, ammonia borane represented by the chemical formula: NH3BH3 into contact with (1) a catalyst comprising as an active ingredient at least one member selected from the group consisting of metal catalysts and metal compound catalysts; (2) a solid acid; or (3) carbon dioxide. The method of the invention can generate hydrogen gas for use as fuel for fuel cells, etc., under controllable conditions without heating a starting material at high-temperature, and moreover can efficiently generate hydrogen gas at low cost.

Description

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a hydrogen generation method.

(2) Description of the Related Art

Various methods for generating hydrogen gas are currently known, and specific examples thereof include the electrolysis of water; the reaction between metal and acid; the reaction of water with metal hydride; the reformation of methyl alcohol or natural gas with steam; the release of hydrogen from hydrogen storage materials, such as hydrogen storage metal alloys, activated carbon, carbon nanotubes and lithium-nitrides, etc. However, these methods are disadvantageous in that much energy is required to generate hydrogen, the amount of hydrogen generated is small relative to the amount of starting materials used, large-scale equipment is required, etc. Due to such disadvantages, although these methods are applicable to the hydrogen generation in industrial scale or in laboratory scale, these methods are not suitable for use in supplying hydrogen to fuel cells for automobiles; portable fuel cells for cellular phones, personal computers, etc. and like fuel cells in which a required amount of hydrogen needs to be continuously supplied and a system should be small.

On the other hand, metal hydrides, such as LiAlH₄, NaBH₄, etc., are used as hydrogenation reagents in laboratories, etc. Such compounds rapidly release a large amount of hydrogen in contact with water to bring about an explosion-like phenomenon, and thus the compounds need to be handled carefully. Also in this respect, such compounds are not suitable for use as hydrogen supply sources for the above-described fuel cells.

Further, a method for generating hydrogen from an aqueous alkaline solution of tetrahydroborate such as NaBH₄, etc., has been reported, however, this method requires control of the alkalinity (pH value), and moreover requires careful handling as described above. (S. C. Amendola, et al., International Journal of Hydrogen Energy, 25 (2000), pp. 969-975; Z. P. Li, et al., Journal of Power Source, 126 (2004) pp. 28-33; Japanese Unexamined Patent Publication No. 2001-19401; and Japanese Unexamined Patent Publication No. 2002-241102; etc.)

In addition, a method for generating hydrogen utilizing the thermal decomposition of ammonia borane represented by the chemical formula: NH₃BH₃ has been reported. However, since ammonia borane is heated at a high temperature for thermal decomposition in the method, a large quantity of energy is needed and control of the reaction is difficult (V. Sit, et al., Thermochimica Acta, 113 (1987) 379; A.T-Raissi, Proceedings of the 2002 US DOE Hydrogen Program Review).

SUMMARY OF THE INVENTION

The invention was made in view of the prior-art problems, and a principal object of the invention is to provide a novel hydrogen generation method capable of efficiently generating hydrogen gas for use as fuel for fuel cells, etc., under controllable conditions without heating a starting material at high-temperature.

The inventors carried out various studies focusing on ammonia borane represented by the chemical formula: NH₃BH₃ as a hydrogen source material and found the following properties of ammonia borane. That is, although ammonia borane is soluble in water to form a highly stable aqueous solution, the aqueous solution generates hydrogen gas when it is brought into contact with a specific substance. The amount of hydrogen to be generated and the generation rate of hydrogen from the aqueous solution can be easily controlled. The present invention was accomplished based on these findings.

More specifically, the invention provides the following hydrogen generation methods and hydrogen supply methods for supplying hydrogen to fuel cells.

• Item 1. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH₃BH3 into contact with at least one catalyst selected from the group consisting of metal catalysts and metal compound catalysts in the presence of water.

• Item 2. The hydrogen generation method according to Item 1, wherein the catalyst is at least one member selected from the group consisting of platinum, palladium, nickel, cobalt, rhodium and compounds containing at least one of the above metals.
• Item 3. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH₃BH₃ into contact with a supported metal catalyst in the presence of water, the supported metal catalyst comprising at least one metal component selected from the group consisting of elements of Group 8, elements of Group 9, elements of Group 10 and elements of Group 11 of the periodic table supported on an inorganic oxide carrier.

• Item 4. The hydrogen generation method according to Item 3, wherein the supported metal catalyst comprises at least one metal component selected from the group consisting of platinum, palladium, rhodium, ruthenium, nickel, cobalt and copper supported on an inorganic oxide carrier.
• Item 5. The hydrogen generation method according to Item 3, wherein the inorganic oxide carrier is at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia.
• Item 6. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH₃BH₃ into contact with a solid acid in the presence of water.

• Item 7. The hydrogen generation method according to Item 6, wherein the solid acid is at least one member selected from the group consisting of H-type zeolites and polymer compounds having sulfonic acid groups.
• Item 8. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH₃BH₃ into contact with carbon dioxide in the presence of water.

• Item 9. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of Item 1 to a fuel cell.

• Item 10. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of Item 3 to a fuel cell.

• Item 11. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of Item 6 to a fuel cell.

• Item 12. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of Item 8 to a fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart showing the change of ¹¹B NMR spectrum with time when an aqueous ammonia borane solution (0.3% by weight) is left at room temperature under an argon atmosphere.

FIG. 2 is a graph showing the relationship between the amount of hydrogen released and the reaction time measured in each of Examples 1, 2 and 4 to 9.

FIG. 3 is a graph showing the relationship between the amount of hydrogen released and the reaction time measured in each of Examples 10 to 12.

FIG. 4 is a graph showing the relationship between the amount of hydrogen released and the reaction time measured in each of Examples 14 to 16.

FIG. 5 is a chart showing the change of ¹¹B NMR spectrum with time measured in Example 17.

FIG. 6 is a graph showing the relationship between the amount of hydrogen released from an aqueous NH₃BH₃ solution (10 ml, 1 wt %) and the reaction time in each of Examples 19, 20 and 22.

FIG. 7 is a graph showing the relationship between the amount of hydrogen released from an aqueous NH₃BH₃ solution (10 ml, 1 wt %) and the reaction time measured in the hydrogen generation test of Example 21.

FIG. 8 is a graph showing the relationship between the amount of hydrogen released from an aqueous NH₃BH₃ solution (10 ml, 1 wt %) and the reaction time measured in the hydrogen gas generation test of each of Examples 23, 24 and 25.

DETAILED DESCRIPTION OF THE INVENTION

Starting material

The hydrogen generation method of the invention uses ammonia borane represented by the chemical formula: NH₃BH₃ as a starting material. Ammonia borane is a known colorless compound with a density of 0.74 g/cm³. Ammonia borane, although it is soluble in water, is unlikely to react with water at around room temperature, and thus, it can exist as a relatively stable solution, offering easy and safe handling.

Any type of ammonia borane can be used without limitation, and generally commercially-available ammonia borane can be used as such. Other components may be contained, insofar as hydrogen generation is not adversely affected.

The hydrogen generation method of the invention uses the above-described ammonia borane as a starting material, and comprises the step of bringing, in the presence of water, ammonia borane into contact with (1) a catalyst comprising as an active ingredient at least one member selected from the group consisting of metal catalysts and metal compound catalysts; (2) a solid acid; or (3) carbon dioxide; thereby generating hydrogen. Hereinafter, each hydrogen generation method is specifically described.

Method of Bringing Ammonia Borane into Contact with a Catalyst Comprising, as an Active Ingredient, a Metal Catalyst or a Metal Compound Catalyst

FIG. 1 shows ¹¹B NMR spectra of an aqueous ammonia borane solution (0.3% by weight) immediately after, 6 days after and 30 days after the aqueous solution is prepared and left at room temperature under an argon atmosphere. As can be seen from these spectra, in the ¹¹B NMR measurement, the peak (δ=−24 ppm) which belongs to NH₃BH₃ hardly changes, and no new peaks are observed after one month. This result shows that NH₃BH₃ is unlikely to react with water even if the aqueous NH₃BH₃ solution is left at room temperature for a month.

In contrast, it was clarified from the studies conducted by the inventors that when ammonia borane is, in the presence of water, brought into contact with a catalyst comprising as an active ingredient a metal catalyst or a metal compound catalyst, ammonia borane reacts promptly with water to thereby generate hydrogen according to the following chemical reaction scheme (1):

In this reaction, the amount of hydrogen generated is the sum of the amount of hydrogen generated by decomposition of NH₃BH₃ itself and the amount of hydrogen generated from water, and thus 8.9% by weight of hydrogen is obtained, based on the total weight of NH₃BH₃ and H₂O which play a part in the reaction, thereby achieving a high hydrogen generation efficiency.

(1) Catalyst Component

Among the catalyst components used in the method of the invention, examples of preferable metal catalysts include metals such as elements of Group 8, elements of Group 9, elements of Group 10 and elements of Group 11 of the periodic table, and particularly preferable examples include metals such as elements of Group 9 and elements of Group 10 of the periodic table. In particular, cobalt, nickel, rhodium, palladium, platinum, etc. are preferable.

Examples of metal compound catalysts include compounds comprising at least one metal component selected from the group consisting of elements of Group 8, elements of Group 9, elements of Group 10 and elements of Group 11 of the periodic table. In particular, compounds comprising at least one metal component selected from the group consisting of elements of Group 9 of the periodic table and compounds comprising at least one metal component selected from the group consisting of elements of Group 10 of the periodic table are preferable.

Since the hydrogen generation reaction of the invention proceeds under a strong reducing atmosphere, a compound comprising at least one of the above-mentioned metals may be reduced to the metal during the reaction to thereby effectively act as a catalyst. There is no limitation on the compound type, and various types of compounds, such as salts (e.g., sulfates), oxides and complexes, can be used.

Specific examples of metals and metal compounds which exhibit high catalytic activity include platinum oxide, platinum, potassium tetrachloroplatinate (II), palladium sulfate, palladium, nickel sulfate, cobalt sulfate, di-μ-chlorobis(η-cycloocta-1,5-diene)rhodium (I) ([Rh(1,5-COD) (μ-Cl)]₂), etc.

The above-mentioned metal catalysts and metal compound catalysts can be used alone or as a mixture thereof.

When at least one metal component selected from the group consisting of the above-mentioned metal catalysts such as elements of Group 8, elements of Group 9, elements of Group 10 and elements of Group 11 of the periodic table is supported on an inorganic oxide carrier, the supported metal catalyst thus obtained, even in a small amount, shows a higher activity for the hydrolysis reaction of ammonia borane compared to the use of a catalyst comprising only the metal component. Therefore, the use of such a supported metal catalyst wherein a metal component is supported on an inorganic oxide carrier achieves generating hydrogen more efficiently at low cost.

Examples of particularly preferable metal components to be supported on an inorganic carrier can be mentioned as follows: iron, ruthenium and like elements can be mentioned as elements of Group 8 of the periodic table; cobalt, rhodium and like elements can be mentioned as elements of Group 9 of the periodic table; nickel, palladium, platinum and like elements can be mentioned as elements of Group 10 of the periodic table; and copper, silver, gold, and like elements can be mentioned as elements of Group 11 of the periodic table. Such metal components can be used alone or as a mixture thereof. Preferable are supported metal catalysts comprising, as a metal component, platinum, palladium, rhodium, ruthenium, nickel, cobalt, copper, etc., among the above metal components.

Examples of inorganic oxides to be used as a carrier include metal oxides, composite metal oxides, zeolites, mesoporous silica, and like oxides. Specific preferable examples of carriers include alumina, silica, titania, zirconia, and like metal oxides.

The carriers used in the invention are not limited in form, size, etc. insofar as they can support at least one of the above-mentioned metal components, and inorganic oxides in various forms such as powders, granules and other forms of molded articles can be used as carriers. In particular, porous carriers are advantageous in that the amount of metal component supported per unit weight is large.

In the above-described supported metal catalysts, the optimum range of the amount of the metal component supported may be suitably determined depending on the specific reaction temperature, reaction system, carrier form, etc. In general, the amount of metal component may be about 0.1% by weight to about 50% by weight, and preferably about 0.5% by weight to about 20% by weight, when the total amount of metal component and an inorganic oxide carrier is 100% by weight.

Specific examples of supported metal catalysts which show noticeably high catalytic activity include ruthenium supported on silica, platinum supported on alumina, palladium supported on titania, rhodium supported on zirconia, nickel supported on alumina, cobalt supported on silica, copper supported on alumina, etc.

Such supported metal catalysts can be used alone or as a mixture thereof.

Metal components can be supported on carriers by any of known preparation methods without limitation, and such methods are suitably selected from impregnation methods, precipitation methods, etc. According to, for example, the impregnation method, a supported metal catalyst can be prepared as follows: a metal salt, an inorganic oxide carrier and water are stirred in a container such as a flask, followed by evaporation of water, and then heating, and, if required, treatment with a reducing agent such as hydrogen, etc. is conducted, thereby obtaining a desired supported metal catalyst. Methods for evaporating water are not limited, and for example, water is evaporated by depressurization with a pump, heating, etc. There is also no limitation on heating temperature, and, in general, heating is preferably conducted at a temperature near or above the decomposition temperature of the metal salt. When such a heating procedure alone is insufficient to reduce the metal component, a reduction treatment may be conducted, if necessary. A reduction treatment may be conducted by, for example, heating the metal salt at a suitable temperature in a hydrogen atmosphere. Ammonia borane used as a starting material in the invention also acts as a reducing agent. Thus, when a metal which is easy to be reduced is used as a metal component, a compound comprising such a metal component is also reduced to become metal when it is brought into contact with ammonia borane to generate hydrogen. Therefore, reduction with another reducing agent can be omitted.

(2) Hydrogen Generation Method

In the method of the invention, hydrogen is generated by bringing ammonia borane represented by the chemical formula: NH₃BH₃ into contact with one of the above-described catalysts in the presence of water. There is no limitation on the method of bringing ammonia borane into contact with the catalyst. More specifically, the following methods can be adopted, for example: adding water to a mixture of ammonia borane and a catalyst; dissolving or dispersing either or both of ammonia borane and a catalyst in water and then mixing ammonia borane and the catalyst. In the former case, the hydrogen generation rate, amount of hydrogen to be generated, etc., can be easily controlled by adjusting, for example, the water addition rate, amount of water added, etc. In the latter case, the hydrogen generation rate, amount of hydrogen to be generated, etc., can be easily controlled by adjusting, for example, the mixing rate, mixing proportion of ammonia borane and catalyst, the concentration of the aqueous solution(s), etc.

As shown in the above reaction scheme, 2 moles of water react with 1 mole of ammonia borane to generate hydrogen. In view of this, in order to completely react ammonia borane as the starting material, the amount of water is preferably about 2 moles or more per mole of ammonia borane.

The solubility of ammonia borane in water is about 26% by weight at 23° C. When ammonia borane is dissolved in water, an aqueous ammonia borane solution with a concentration up to its saturated concentration can be used. Alternatively, an aqueous ammonia borane solution with a concentration above its saturated concentration, which contains undissolved ammonia borane, may be used. There is no limitation to the lower limit of ammonia borane concentration of the aqueous solution, and the concentration of ammonia borane may be extremely low, e.g., 0.1% by weight or lower.

The amount of the catalyst may be suitably determined depending on a desired hydrogen generation rate, hydrogen generation cost, etc., considering the fact that hydrogen generation can be promoted as the amount of the catalyst is increased. In the case of the use of at least one catalyst selected from the group consisting of metal catalysts and metal compound catalysts, the amount of the catalyst can be selected from within a wide range of about 0.0001 mole to about 10 moles per mole of ammonia borane. In view of the balance of reaction rate, catalyst cost, etc. the amount of the catalyst is, for example, preferably about 0.001 mole to about 0.5 mole per mole of ammonia borane.

Supported metal catalysts show extremely high activity in generating hydrogen from ammonia borane, and can promote hydrogen generation with a smaller amount of catalyst. The amount of metal compound supported may be, for example, about 0.00001 mole to about 5 moles per mole of ammonia borane. In view of the balance between reaction rate, catalyst cost, etc., the amount of metal component(s) in the supported metal catalyst is preferably about 0.0001 mole to about 0.1 mole per mole of ammonia borane.

The reaction temperature is not limited, and is preferably not less than 0° C., i.e., the freezing point of water, and not more than about 80° C., and is more preferably about 10° C. to about 50° C.

There is no limitation to the pressure and atmosphere during the reaction in the reaction system, and they can be suitably determined.

Method of Bringing Ammonia Borane into Contact with Solid Acid

Also when ammonia borane is brought into contact with a solid acid, ammonia borane and water react promptly to generate hydrogen according to the above chemical reaction scheme (1).

Any solid acid can be used without limitation insofar as they do not dissolve in the reaction solution and show the properties as Bröbnsted-acid and/or Lewis-acid. For example, polymer compounds with sulfonic acid groups, H-type zeolites, etc. can be used. There is no limitation to the concentration of acidic sites of such solid acids, and solid acids with a cation exchange capacity of, for example, about 0.01 to about 10 meq/g, and preferably about 0.1 to about 5 meq /g, can be used.

In the invention, sulfonic acid group-containing polymer compounds are not limited in terms of polymer structures. Any polymer compounds containing sulfonic acid groups bonded thereto can act as a catalyst. The use of compounds whose properties do not change in the reaction system is preferable. In general, polymer compounds containing sulfonic acid groups bonded to a side chain of a styrene-based resin, such as styrene polymers, styrene-divinylbenzene copolymers; fluorine-containing resins; etc., are industrially readily available as ion-exchange resins. For example, usable are styrene-based resins commercially available under the following trade names: “Amberlyst” (registered trademark of Rohm and Haas), “Amberlite” (registered trademark of Rohm and Haas), “DOWEX” (registered trademark of the Dow Chemical Co.), etc. Examples of fluorine-containing resins include perfluorosulfonic acid-based resins commercially available under the following trade names: Nafion NR-50, Nafion SAC-13 (both of which are registered trademarks of Du Pont). Such perfluorosulfonic acid-based resins may be represented by the following structural formula:

Specific examples of H-type zeolites include H-Y zeolites, H-β zeolites, H-mordenite zeolites, etc.

Ammonia borane represented by the chemical formula: NH₃BH₃ is brought into contact with the solid acid in the presence of water in the same manner as the above-described method using a catalyst comprising at least one member selected from the group consisting of metal catalysts and metal compound catalysts as an active ingredient.

The amount of water, reaction conditions and the like may be determined in the same manner as in the method using the above-described catalyst.

The amount of solid acid varies depending on the strength and concentration of the acidic sites of the solid acid and the like, and thus cannot be generally determined. For example, the equivalent number of the acidic sites of solid acid can be, for example, about 0.0001 eq to about 10 eq, and preferably about 0.01 eq to about 2 eq per mole of ammonia borane.

The resultant product may react with the acidic sites of the solid acid to thereby lower the activity of acidic sites. In this case, the activity of the solid acid can be recovered by washing with an acidic solution after the reaction.

Method of Bringing Ammonia Borane into Contact with Carbon Dioxide In the Invention, Hydrogen can also be Generated by Bringing Ammonia Borane into Contact with Carbon Dioxide in the Presence of Water.

More specifically, hydrogen can be generated by introducing carbon dioxide from a gaseous phase or a liquid phase into a reaction container containing an aqueous ammonia borane solution. There is no limitation on the amount of carbon dioxide introduced. Carbon dioxide may be introduced under pressure of about 0.01 MPa to about 0.5 MPa, and preferably about 0.03 MPa to 0.2 MPa. Carbon dioxide may be used alone or as a mixture with inert gas(es).

The amount of water and reaction conditions may be determined in the same manner as in the method using the above-described catalyst.

In this method, the amount of hydrogen generated, generation rate, etc. can be easily controlled by adjusting the introduction amount and introduction rate of carbon dioxide, the concentration of the aqueous ammonia borane solution, etc. Applications of hydrogen generation method Hydrogen generated by the method of the invention can be directly supplied to fuel cells as fuel therefor. In particular, since the method of the invention can generate hydrogen at around room temperature and can also control hydrogen generation rate, generation amount, etc., the method is highly useful as hydrogen supply methods for fuel cells for automobiles; portable fuel cells for cellular phones, personal computers, etc. and like fuel cells.

The hydrogen generated can be collected and stored in a container filled with, for example, a hydrogen storage alloy. Further, the pressure in the system containing a hydrogen storage alloy can be controlled by adjusting the temperature based on the relationship between equilibrium pressure and temperature.

As described above, the hydrogen generation method of the invention can efficiently generate hydrogen gas under controllable conditions without heating a starting material to high temperature. In particular, with the use of the above-described supported metal catalysts, even if the amount of metal component contained therein is small, the supported metal catalysts show a high activity in generating hydrogen. Therefore, a large amount of hydrogen can be efficiently generated in a short reaction time.

Thus, the hydrogen generation method of the invention is extremely useful as a hydrogen generation method capable of efficiently generating hydrogen at low cost.

Hydrogen gas generated by the method of the invention is useful as fuel for fuel cells for automobiles, portable fuel cells, etc.

EXAMPLES

Hereafter, the invention is described in more detail with reference to Examples.

Example 1

4.0 mg of platinum oxide (PtO₂) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 39 ml of gas had been released; two minutes after, 65 ml; 5 minutes after, 87 ml; 10 minutes after, 105 ml; and 30 minutes after, 107 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the gas released was hydrogen. The amount of hydrogen released was 3 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 2

4.0 mg of platinum (Pt) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 12.5 ml of gas had been released; two minutes after, 23.5 ml; 5 minutes after, 53.5 ml; 10 minutes after, 97.5 ml; and 30 minutes after, 105 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 3

After the reaction of Example 2 was complete, platinum (Pt) powder was collected by filtration and placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 11 ml of gas had been released; two minutes after, 22 ml; 5 minutes after, 51 ml; 10 minutes after, 97 ml; and 30 minutes after, 105 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 4

4.8 mg of potassium tetrachloroplatinate (II) (K₂PtCl₄) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 1.5 ml of gas had been released; two minutes after, 5.5 ml; 5 minutes after, 18.5 ml; 10 minutes after, 45.5 ml; and 30 minutes after, 99 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.8 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 5

5.0 mg of palladium sulfate (PdSO₄) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 5.5 ml of gas had been released; 10 minutes after, 8.0ml; 60minutes after, 27ml; 120minutes after, 47 ml; and 240 minutes after, 71 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 6

4.5 mg of palladium (Pd) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 3.0 ml of gas had been released; 10 minutes after, 35 ml; 60 minutes after, 15.5 ml; 120 minutes after, 27.5 ml; 240 minutes after, 53 ml; and 360 minutes after, 71.5 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 7

4.3 mg of nickel sulfate (NiSO₄) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 1.0 ml of gas had been released; 10 minutes after, 1.5 ml; 60 minutes after, 8.0 ml; 120 minutes after, 31 ml; 240 minutes after, 86.5 ml; and 300 minutes after, 92 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.6 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 8

4.3 mg of cobalt sulfate (CoSO₄) powder was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 1.0 ml of gas had been released; 10 minutes after, 3.0 ml; 30 minutes after, 43 ml; 60 minutes after, 95 ml; and 80 minutes after, 98 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.8 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 9

5.0 mg of powder of di-μ-chlorobis(η-cycloocta-1,5-diene) rhodium (I) ([Rh(1,5-COD) (μ-Cl)]₂), was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 2.0 ml of gas had been released; 2 minutes after, 6.0 ml; 5 minutes after, 28 ml; 10 minutes after, 75 ml; 30 minutes after, 91 ml; and 60 minutes after, 91 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.6 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

FIG. 2 is a graph showing the relationship between the amount of hydrogen generated and the reaction time in each of Examples 1, 2 and 4 to 9. The result shows that the catalysts used in Examples 1, 2 and 4 to 9 are all useful for hydrogen generation by the reaction between ammonia borane (NH₃BH₃) and water.

Example 10

In a 50 ml two-necked flask were placed 1700 mg of H-type perfluorosulfonic acid-based resin (trade name: Nafion NR-50, product of Dupont) (cation exchange capacity: about 0.8 meq/g (resin)) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 2.0 ml of gas had been released; 5 minutes after, 6.5 ml; 10 minutes after, 15.0 ml; 30 minutes after, 47.5 ml; 60 minutes after, 75.5 ml; and 120 minutes after, 92 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.6 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 11

In a 50 ml two-necked flask were placed 600 mg of H-type styrene-based ion exchange resin (trade name: DOWEX 50WX8-100, product of Dow Chemical) (cation exchange capacity: about 1.7 meq/ml (resin)) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. An aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 49.5 ml of gas had been released; 2 minutes after, 79.5 ml; 3 minutes after, 88.5 ml; 5 minutes after, 94.5 ml; and 10 minutes after, 97.5 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.7 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 12

In a 50 ml two-necked flask were placed 600 mg of H-type styrene-based ion exchange resin (trade name: Amberlyst 15, product of Rohm and Hass) (cation exchange capacity: about 4.7 meq/g (resin)) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 40 ml of gas had been released; 2 minutes after, 76.5 ml; 3 minutes after, 91.5 ml; 5 minutes after, 99.5 ml; and 10 minutes after, 101 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.8 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

FIG. 3 is a graph showing the relationship between the amount of hydrogen generated and the reaction time in each of Examples 10 to 12. The result shows that the solid acids used in Examples 10 to 12 are all useful for hydrogen generation by the reaction between ammonia borane (NH₃BH₃) and water.

Example 13

After the reaction of Example 12 was complete, the ion exchange resin (Amberlyst 15) was collected by filtration. The collected resin was immersed in 10 ml of 10% sulfuric acid for 1 hour. After filtration, the resultant was washed with water5 times and dried at 90° C. for 30 minutes.

In a 50 ml two-necked flask were placed the ion exchange resin (Amberlyst 15) thus collected and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 39 ml of gas had been released; 2 minutes after, 75 ml; 3 minutes after, 90.5 ml; 5 minutes after, 99 ml; and 10 minutes after, 100 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.8 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 14

In a 50 ml two-necked flask were placed 8 g of H-Y zeolite (SiO₂/Al₂O₃=4.8) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 11 ml of gas had been released; 10 minutes after, 21 ml; 30 minutes after, 45.5 ml; 60 minutes after, 63.5 ml; and 180 minutes after, 84 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.4 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 15

In a 50 ml two-necked flask were placed 7 g of H-β zeolite (SiO₂/Al₂O₃=25) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH3, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 34 ml of gas had been released; 10 minutes after, 48 ml; 20 minutes after, 64 ml; 30 minutes after, 73 ml; and 60 minutes after, 79 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.2 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 16

In a 50 ml two-necked flask were placed 5 g of H-mordenite zeolite (SiO₂/Al₂O₃=15) and 15 ml of water. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 15 ml of aqueous solution in which 50 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 24 ml of gas had been released; 10 minutes after, 35 ml; 30 minutes after, 61 ml; 60 minutes after, 77.5 ml; and 120 minutes after, 88 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.5 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

FIG. 4 is a graph showing the relationship between the amount of hydrogen generated and the reaction time in each of Examples 14 to 16. The result shows that the solid acids used in Examples 14 to 16 are all useful for hydrogen generation by the reaction between ammonia borane (NH₃BH₃) and water.

Example 17

100 mg of ammonia borane (NH₃BH₃, 90% purity) and 15 ml of water (H₂O) were placed in a 200 ml two-necked flask connected to a 400 ml gas bag. After stirring and dissolving the contents, carbon dioxide was introduced into the flask at one atmosphere pressure (0.1 MPa). The mixture was stirred at room temperature, and ¹¹B NMR was measured with time. FIG. 5 is a graph showing the change of ¹¹B NMR spectrum with time. The spectra showed that 70% of ammonia borane had reacted after three days. ¹¹B NMR spectrum after seven days showed that −24 ppm peak for ammonia borane had disappeared completely, and only 19.24 ppm peak mainly for H₃BO₃ was observed.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.3 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 18

In a flask were placed 144 mg of ruthenium chloride (RuCl₃), 6 g of silica (SiO₂) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 10 minutes, heated to 70° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 250° C. for 1 hour in air, a heat treatment at 400° C. was conducted for 1.5 hours with hydrogen gas flowing over the sample (30 ml/min). This treatment provided a catalyst comprising ruthenium supported on silica (1.1% by weight ruthenium content based on the total amount of ruthenium and silica).

149 mg of the supported catalyst thus obtained was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. One minute after stirring was started, it was observed that 52 ml of gas had been released; 2 minutes after, 110 ml; 5 minutes after, 214 ml; and 7 minutes after, 214 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 19

In a flask were placed 124 mg of ruthenium chloride (RuCl₃), 3 g of y-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 10 minutes, and heated to 70° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 300° C. for 5 hours in air, heating at 250° C. was carried out for 3 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising ruthenium supported on y-alumina (containing 2% by weight of ruthenium based on the total amount of ruthenium and alumina).

260 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Thirty seconds after stirring was started, it was observed that 57 ml of gas had been released; 1 minute after, 113 ml; 1.5 minutes after, 177 ml; 2 minutes after, 207 ml; and 3 minutes after, 213 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 20

In a flask were placed 104 mg of platinum chloride (PtCl₄), 3 g of γ-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 10 minutes, and heated to 70° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 300° C. for 5 hours in air, heating at 250° C. was carried out for 3 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising platinum supported on γ-alumina (containing 2% by weight of platinum based on the total amount of platinum and alumina).

509 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Thirty seconds after stirring was started, it was observed that 94 ml of gas had been released; 45 seconds after, 215 ml; and 60 seconds after, 215 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 21

In a flask were placed 130 mg of palladium nitrate (Pd(NO₃)₂), 3 g of γ-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 10 minutes, and heated to 70° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 300° C. for 5 hours in air, heating at 250° C. was carried out for 3 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising palladium supported on y-alumina (containing 2% by weight of palladium based on the total amount of palladium and alumina).

280 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 8 ml of gas had been released; 10 minutes after, 16 ml; 30 minutes after, 44 ml; 60 minutes after, 103 ml; 90 minutes after, 163 ml; 120 minutes after, 205 ml; and 180 minutes after, 205 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.9 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 22

In a flask were placed 168 mg of rhodium nitrate (Rh(NO₃)₂), 3 g of γ-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 10 minutes, and heated to 70° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 300° C. for 5 hours in air, heating at 250° C. was carried out for 3 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising rhodium supported on γ-alumina (containing 2% by weight of rhodium based on the total amount of rhodium and alumina).

270 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Fifteen seconds after stirring was started, it was observed that 81 ml of gas had been released; 30 seconds after, 122 ml; 45 seconds after, 163 ml; 60 seconds after, 204 ml; 75 seconds after, 215 ml; 90 seconds after, 215 ml; and 120 seconds after, 215 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Further, 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was additionally introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Seventy five seconds after stirring was started, it was observed that 190 ml of gas had been released; 90 seconds after, 215 ml; and 120 seconds after, 215 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 23

In a flask were placed 935 mg of nickel nitrate (Ni(NO₃)₂), 3 g of γ-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 30 minutes, and heated to 90° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 600° C. for 5 hours in air, heating at 500° C. was carried out for 5 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising nickel supported on γ-alumina (containing 10% by weight of nickel based on the total amount of nickel and alumina).

30 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Thirty minutes after stirring was started, it was observed that 6 ml of gas had been released; 60 minutes after, 35 ml; 90 minutes after, 76ml; 150minutes after, 161 ml; 180 minutes after, 177 ml; and 210 minutes after, 177 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.5 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Further, 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was additionally introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Ten minutes after stirring was started, it was observed that 15 ml of gas had been released; 30 minutes after, 58 ml; 60 minutes after, 121 ml; 90 minutes after, 175 ml; 100 minutes after, 204 ml; and 110 minutes after, 206 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.9 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 24

In a flask were placed 890 mg of copper nitrate (Cu(NO₃)₂), 3 g of y-alumina (y-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 30 minutes, and heated to 90° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 600° C. for 5 hours in air, heating at 500° C. was carried out for 5 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising copper supported on γ-alumina (containing 10% by weight of copper based on the total amount of copper and alumina).

35 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. An aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Ten minutes after stirring was started, it was observed that 4 ml of gas had been released; 30 minutes after, 15 ml; 140 minutes after, 70 ml; 230 minutes after, 122 ml; 390 minutes after, 170 ml; and 420 minutes after, 173 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.4 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 25

In a flask were placed 930 mg of cobalt nitrate (Co(NO₃)₂), 3 g of γ-alumina (γ-Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 30 minutes, and heated to 90° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 600° C. for 5 hours in air, heating at 500° C. was carried out for 5 hours with hydrogen gas flowing over the sample (50 ml/min). This treatment provided a catalyst comprising cobalt supported on γ-alumina (containing 10% by weight of cobalt based on the total amount of cobalt and alumina).

30 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Ten minutes after stirring was started, it was observed that 18 ml of gas had been released; 20 minutes after, 41 ml; 30 minutes after, 62 ml; 60 minutes after, 125 ml; 90 minutes after, 185 ml; 130 minutes after, 207 ml; and 150 minutes after, 207 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.9 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Further, 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was additionally introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Twenty three minutes after stirring was started, it was observed that 60 ml of gas had been released; 30 minutes after, 80 ml; 40 minutes after, 112 ml; 60 minutes after, 170 ml; 80 minutes after, 210 ml; and 100 minutes after, 210 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.9 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Still further, 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was additionally introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Five minutes after stirring was started, it was observed that 17 ml of gas had been released; 10 minutes after, 37 ml; 30 minutes after, 107 ml; 60 minutes after, 205 ml; and 90 minutes after, 208 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.9 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 26

In a flask were placed 740 mg of cobalt nitrate (Co(NO₃)₂), 2.5 g of silica (SiO₂) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 30 minutes, and heated to 90° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 600° C. for 5 hours in air, heating at 500° C. was carried out for 3 hours with hydrogen gas flowing over the sample (30 ml/min). This treatment provided a catalyst comprising cobalt supported on silica (containing 9.5% by weight of cobalt based on the total amount of cobalt and silica).

10.6 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Ten minutes after stirring was started, it was observed that 28 ml of gas had been released; 16minutes after, 89ml; 20 minutes after, 134 ml; 24 minutes after, 183 ml; 30 minutes after, 210 ml; and 40 minutes after, 212 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 3.0 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Example 27

In a flask were placed 1880 mg of cobalt nitrate (Co (NO₃) ₂), 6.0 g of neutral alumina (Al₂O₃) and 10 ml of water (H₂O). The mixture was stirred at room temperature for 30 minutes, and heated to 90° C. The inside of the flask was depressurized with a pump to evaporate water. After heating at 600° C. for 5 hours in air, heating at 500° C. was carried out for 5 hours with hydrogen gas flowing over the sample (30 ml/min). This treatment provided a catalyst comprising cobalt supported on neutral alumina (containing 10% by weight of cobalt based on the total amount of cobalt and alumina).

31 mg of the supported catalyst thus prepared was placed in a 30 ml two-necked flask. A gas burette was connected to one neck and a 50 ml dropping funnel with pressure-equalizing arm was connected to the other neck. 10 ml of aqueous solution in which 100 mg of ammonia borane (NH₃BH₃, 90% purity) was dissolved was placed in the dropping funnel.

The inside of the system was evacuated with a vacuum pump, and then filled with argon gas. The aqueous ammonia borane solution was introduced from the dropping funnel into the two-necked flask, and stirring was conducted at room temperature. Twenty five minutes after stirring was started, it was observed that 4 ml of gas had been released; 60 minutes after, 22 ml; 120 minutes after, 66 ml; 150 minutes after, 96 ml; 220 minutes after, 153 ml; 250 minutes after, 180 ml; 290 minutes after, 202 ml; and 300 minutes after, 202 ml.

Gas chromatographic (GC) and mass spectral (MS) analyses showed that the released gas was hydrogen. The amount of hydrogen released was 2.8 moles per mole of ammonia borane (NH₃BH₃) as a starting material.

Separately, the hydrogen gas generated by the above-described method was introduced into a polymer electrolyte fuel cell, and it was then confirmed that the polymer electrolyte fuel cell normally operated.

Hydrogen Gas Generation Test

FIG. 6 is a graph showing the relationship between the amount of hydrogen generated from the aqueous NH₃BH₃ solution (10 ml, 1 wt. %) and the reaction time measured in each of Examples 19, 20 and 22.

As can be seen from FIG. 6, the ruthenium supported on alumina (2 wt % Ru/γ-Al₂O₃) of Example 19, platinum supported on alumina (2 wt % Pt/γ-Al₂O₃) of Example 20, and rhodium supported on alumina (2 wt % Rh/γ-Al₂O₃) of Example 22 show high activity in generating hydrogen from the aqueous NH₃BH₃ solution. The use of these supported metal catalysts, as compared with the use of a metal catalyst of the same kind which was not supported on an oxide carrier, generated a greater amount of hydrogen in a shorter time.

FIG. 7 is a graph showing the relationship between the amount of hydrogen generated from the aqueous NH₃BH₃ solution (10 ml, 1 wt. %) and the reaction time measured in Example 21 in which palladium supported on alumina (2 wt % Pd/γ-Al₂O₃) was used as a catalyst. The result shows that the palladium supported on alumina (2 wt % Pd/γ-Al₂O₃) has high activity in generating hydrogen from the aqueous NH₃BH₃ solution. The use of the palladium supported on alumina (2 wt % Pd/γ-Al₂03) showed higher activity than the use of a catalyst consisting of only palladium black.

FIG. 8 is a graph showing the relationship between the amount of hydrogen generated from the aqueous NH₃BH₃ solution (10 ml, 1 wt. %) and the reaction time measured in each of Examples 23, 24 and 25. FIG. 8 shows that the catalysts used in Examples 23 to 25 all have high activity in generating hydrogen from the aqueous NH₃BH₃ solution. Among the above, the nickel supported on alumina (10 wt % Ni/γ-Al₂O₃) and the cobalt supported on alumina (10 wt % Co/γ-Al₂O₃) showed higher activities.

Claims

1. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH3BH3 into contact with at least one catalyst selected from the group consisting of metal catalysts and metal compound catalysts in the presence of water.

2. The hydrogen generation method according to claim 1, wherein the catalyst is at least one member selected from the group consisting of platinum, palladium, nickel, cobalt, rhodium and compounds containing at least one of the above metals.

3. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH3BH3 into contact with a supported metal catalyst in the presence of water, the supported metal catalyst comprising at least one metal component selected from the group consisting of elements of Group 8, elements of Group 9, elements of Group 10 and elements of Group 11 of the periodic table supported on an inorganic oxide carrier.

4. The hydrogen generation method according to claim 3, wherein the supported metal catalyst comprises at least one metal component selected from the group consisting of platinum, palladium, rhodium, ruthenium, nickel, cobalt and copper supported on an inorganic oxide carrier.

5. The hydrogen generation method according to claim 3, wherein the inorganic oxide carrier is at least one metal oxide selected from the group consisting of alumina, silica, titania and zirconia.

6. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH3BH3 into contact with a solid acid in the presence of water.

7. The hydrogen generation method according to claim 6, wherein the solid acid is at least one member selected from the group consisting of H-type zeolites and polymer compounds having sulfonic acid groups.

8. A hydrogen generation method comprising:

bringing ammonia borane represented by the chemical formula: NH3BH3 into contact with carbon dioxide in the presence of water.

9. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of claim 1 to a fuel cell.

10. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of claim 3 to a fuel cell.

11. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of claim 6 to a fuel cell.

12. A hydrogen supply method comprising:

supplying the hydrogen generated by the method of claim 8 to a fuel cell.