HYDROGEN STORAGE SYSTEM AND METHOD FOR MANUFACTURING THE SAME

Abstract

Provided is a hydrogen storage system including a solution including ethylenediamine bisborane (EDAB) and ethylenediamine (ED), in which the hydrogen storage system is capable of performing a reversible dehydrogenation/hydrogenation reaction at a temperature of 20° C. to 200° C. in the presence of a heterogeneous metal catalyst including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Jr), platinum (Pt), nickel (Ni), iron (Fe), cobalt (Co), or a combination thereof.

Claims

1. A hydrogen storage system comprising a solution comprising ethylenediamine bisborane (EDAB) and ethylenediamine (ED), wherein the hydrogen storage system is capable of performing a reversible dehydrogenation/hydrogenation reaction at a temperature of 20° C. to 200° C. in the presence of a heterogeneous metal catalyst comprising ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Jr), platinum (Pt), nickel (Ni), iron (Fe), cobalt (Co), or a combination thereof.

2. The hydrogen storage system of claim 1, wherein the hydrogen storage system is capable of performing a reversible dehydrogenation/hydrogenation reaction at room temperature.

3. The hydrogen storage system of claim 1, wherein the heterogeneous metal catalyst comprises Pt.

4. The hydrogen storage system of claim 3, wherein the heterogeneous metal catalyst is Pt/C.

5. The hydrogen storage system of claim 4, wherein a content of the heterogeneous metal catalyst in the solution is 1 to 10 mol %.

6. The hydrogen storage system of claim 1, wherein the solution further comprises a solvent selected from dioxane, tetrahydrofuran (THF), benzene, methyl chloride, n-hexane, dimethyl ether, and a combination thereof.

7. The hydrogen storage system of claim 1, wherein a mixture ratio of EDAB and ED in the solution is 1:1 to 1:10.

8. The hydrogen storage system of claim 1, wherein the hydrogen storage system has a H.sub.2 production rate of 3 equivalents or more per mol of EDAB through a dehydrogenation reaction.

9. A vehicle comprising the hydrogen storage system of claims 1.

10. A method for preparing a hydrogen storage system, the method comprising: preparing EDAB; preparing a solution by mixing the EDAB and ED; and loading a heterogeneous metal catalyst into the solution.

11. The method of claim 10, wherein the EDAB is obtained by reacting a borane-complex and an amine compound.

12. The method of claim 11, wherein the borane-complex and the amine compound are reacted at a ratio of 2:1.

13. The method of claim 11, wherein the borane-complex is borane dimethyl sulfide (BH.sub.3DMS).

14. The method of claim 11, wherein the amine compound is ED.

15. The method of claim 10, wherein a mixture ratio of EDAB and ED in the solution is 1:1 to 1:10.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1A illustrates the amount of hydrogen generated of an EDAB/ED system under 1 mol % of a Pt/C catalyst.

[0025] FIG. 1B illustrates the amount of hydrogen generated of a catalyst EDAB/ED system in 1 mol % of NiCl.sub.2, FeCl.sub.2, and CoCl.sub.2, respectively.

[0026] FIG. 2 is an MS analysis result of main compounds produced after a dehydrogenation reaction.

[0027] FIGS. 3A to 3C are proposed structures and molecular formulae of main compounds produced after a dehydrogenation reaction.

[0028] FIG. 4 illustrates .sup.11B NMR spectra of EDAB and dehydrogenation and rehydrogenation products thereof.

[0029] FIG. 5 illustrates a transfer pathway of hydrogen based on the hydrogen storage material system of the present invention.

BEST MODE

[0030] In the present invention, a hydrogen storage system including a solution including ethylenediamine bisborane (EDAB) and ethylenediamine (EDA) releases a considerable amount of H.sub.2 gas by undergoing a dehydrogenation reaction at an excellent reaction rate under room temperature conditions.

[0031] Since the hydrogen storage system including EDAB and ED has a low dehydrogenation reaction temperature and a low hydrogenation reaction enthalpy, high temperature and high pressure conditions are not required during the dehydrogenation reaction.

[0032] EDAB is suitable for dehydrogenation and hydrogenation reactions by having a high proportion of B—H and N—H bonds in the molecule. EDAB has excellent kinetics such that hydrogen is adsorbed/desorbed in a short time in the presence of a heterogeneous metal catalyst.

##STR00001##

[0033] An exemplary embodiment of the present invention provides a hydrogen storage system including a solution including ethylenediamine bisborane (EDAB) and ethylenediamine (ED), in which the hydrogen storage system is capable of performing a reversible dehydrogenation/hydrogenation reaction at a temperature of 20° C. to 200° C. in the presence of a heterogeneous metal catalyst including ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Jr), platinum (Pt), nickel (Ni), iron (Fe), cobalt (Co), or a combination thereof.

[0034] In an exemplary embodiment of the present invention, the hydrogen storage system is capable of performing a reversible dehydrogenation/hydrogenation reaction at room temperature. In an exemplary embodiment of the present invention, the hydrogen storage system is present in the form of a solution at room temperature.

[0035] The solution including ethylenediamine bisborane (EDAB) and ethylenediamine (ED) may include dioxane, tetrahydrofuran (THF), benzene (benzene), methyl chloride, n-hexane), dimethyl ether, and a combination thereof as an additional solvent.

[0036] In the presence of a heterogeneous metal catalyst, a dehydrogenation reaction occurs between BH.sub.3 in EDAB and NH.sub.2 in ED, which are present in the hydrogen storage system, and in this case, ED is considered to play an important role in the dehydrogenation reaction of EDAB.

[0037] In an exemplary embodiment of the present invention, EDAB and ED in the solution may be mixed at a ratio of 1:1 to 1:10, and as a preferred exemplary embodiment, it is preferred that EDAB and ED are mixed at a ratio of 1:5. As an example, the hydrogen storage system may include a solution of 2 mmol EDAB in 1 mL of 1 mmol ED. If the mixture ratio of EDAB and ED is lower than the above range, EDAB may not be dissolved, and if the mixture ratio is higher than the above range, the reactivity may be reduced.

[0038] During the dehydrogenation reaction of the hydrogen storage system of the present invention, the H2 production rate per mol of EDAB is 3 equivalents or more, and preferably 4 equivalents, 5 equivalents, 6 equivalents or more. The hydrogen storage system of the present invention undergoes a dehydrogenation reaction in the presence of a heterogeneous metal catalyst. As used herein, the ‘heterogeneous catalyst’ means that the phase of a catalyst is different from that of a material which reacts with the catalyst. A metal of the heterogeneous metal catalyst may be preferably one or more transition metals selected from the group consisting of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt) among platinum metals belonging to Group 8 of the Periodic Table, and preferably includes platinum (Pt). As an exemplary embodiment of the present invention, the heterogeneous catalyst may be a metal/C catalyst based on the above-described metal, that is, a catalyst including a carbon-based support, and may be for example, a charcoal having ions such as Pt, Ru, Rh, and Pd mixed therein. As the most preferred example, the heterogeneous metal catalyst is Pt/C. As the heterogeneous metal catalyst, one or more of the above-described catalysts may be used.

[0039] The heterogeneous metal catalyst is provided to improve reversible hydrogen storage properties. The amount of heterogeneous metal catalyst needs to be determined within a limit that the effect of the catalyst is sufficiently exhibited and the hydrogen storage capacity is not significantly reduced by the catalyst, and the content of the heterogeneous metal catalyst in the solution may be 1 to 10 mol %. The heterogeneous metal catalyst is easily recovered for a subsequent catalytic cycle.

[0040] Another exemplary embodiment of the present invention provides a method for preparing the hydrogen storage system.

[0041] The method for preparing the hydrogen storage system includes: preparing EDAB; preparing a solution by mixing the EDAB and ED; and loading a heterogeneous metal catalyst into the solution.

[0042] As an exemplary embodiment, the EDAB may obtained by reacting a borane-complex and an amine compound. In this case, the borane-complex and the amine compound are mixed and reacted, and as an exemplary embodiment, the borane-complex and the amine compound are reacted at a ratio of 1:1 to 1:10, preferably at a ratio of 2:1, during the reaction. As the borane-complex, a borane pyridine complex, a borane picoline complex, a borane tetrahydrofuran complex, and a borane dimethyl sulfide complex may be included, and as an example of the amine compound, ethylenediamine (ED), and the like may be used.

[0043] As a preferred example, borane dimethyl sulfide (BH3DMS) and ED may be reacted at a ratio of 2:1.

[0044] A solution is prepared by mixing ED with EDAB prepared from the reaction. In this case, the mixture ratio of EDAB and ED in the solution is 1:1 to 1:10, and preferably 1:5.

[0045] After a solution including the EDAB and the ED is prepared, a hydrogen storage system is prepared by loading a heterogeneous metal catalyst in the solution. The solution may further include a solvent such as dioxane, tetrahydrofuran (THF), benzene, methyl chloride, n-hexane, and dimethyl ether.

EXAMPLES

Preparation Example 1: Synthesis of Ethylenediamine Bisborane (EDAB)

[0046] EDAB was synthesized by mixing a borane-complex, for example, borane dimethyl sulfide (BH.sub.3DMS) and ethylenediamine (ED) at a ratio of 2:1 and reacting the resulting mixture at a standard temperature under a standard pressure for several hours. Dimethyl sulfide was used only as a solvent, and EDAB was obtained as a high-purity white powder by removing the solvent and an excessive amount of BH.sub.3-DMS under vacuum.

##STR00002##

Example 1: Dehydrogenation Reaction of Ethylenediamine Bisborane (EDAB)

[0047] The solution obtained by mixing EDAB and ED obtained in the Preparation Example was subjected to a dehydrogenation reaction by the following method in the presence of a heterogeneous metal catalyst (Pt/C).

[0048] The solution of 2 mol EDAB dissolved in 1 mL of ED with 1 to 2 mol % Pt/C catalyst loading was completely dehydrogenated at room temperature for 1 hour. As a result, 6 equivalents of H.sub.2 gas per mol EDAB were released.

Comparative Example 1

[0049] The amount of hydrogen generated over time from the EDAB/ED system was measured by using the same method in Example 1 and using NiCl.sub.2 instead of the Pt/C catalyst.

Comparative Example 2

[0050] The amount of hydrogen generated over time from the EDAB/ED system was measured by using the same method in Example 1 and using FeCl.sub.2 instead of the Pt/C catalyst.

Comparative Example 3

[0051] The amount of hydrogen generated over time from the EDAB/ED system was measured by using the same method in Example 1 and using CoCl.sub.2 instead of the Pt/C catalyst.

[0052] FIGS. 1A and 1B express the results of each of Example 1 and Comparative Examples 1 to 3 described above in terms of the molar equivalent of H.sub.2 per mol of EDAB. As can be seen from FIGS. 1A and 1B, it was confirmed that in the case of Example 1, the dehydrogenation proceeded in a much shorter time and an excessive amount of hydrogen was generated.

Experimental Example 1: Confirmation of Dehydrogenation Products

[0053] After the reaction of Example 1 was completed, a high resolution MS analysis was performed to confirm dehydrogenation products. As a result, as illustrated in FIG. 2, three main compounds were confirmed. The proposed molecular formulae of these main compounds are illustrated in FIGS. 3A to 3C.

[0054] Since the main compounds illustrated in FIGS. 3A to 3C have a ‘nitrogen-boron-nitrogen’ substructure having a double bond in the molecule, the compounds can be reduced by NaBH.sub.4 at room temperature. In FIGS. 3A to 3C, the upper graph illustrates experimental spectra of m/z, and the lower graph illustrates theoretical isotope element patterns of m/z.

[0055] FIG. 4 illustrates .sup.11B NMR spectra of EDAB and dehydrogenation and rehydrogenation products thereof, and FIG. 5 illustrates a transfer pathway of hydrogen based on the hydrogen storage system of the present invention.

[0056] According to FIG. 4, a reduced product may be obtained by dehydrogenating EDAB and again reducing the dehydrogenated EDAB in the presence of a heterogeneous metal catalyst. Therefore, the dehydrogenation products illustrated in FIGS. 3A to 3C can be recycled by a reduction reaction by H.sub.2 gas (see FIG. 5). In this case, EDAB can be reproduced by reduction by NaBH.sub.4 in the presence of a catalytic content of H.sub.2O. When a catalytic content of H.sub.2O is absent, the reduction reaction may occur, but the reaction is incomplete, and the dehydrogenation products and the remaining NaBH.sub.4 continue to remain even after 24 hours. In contrast, in the H.sub.2O catalyzed reduction, none of dehydrogenation products or NaBH.sub.4 remains. The effect of the H.sub.2O catalyst implies the role of H.sub.2 produced in situ in the rehydrogenation process, indicating that the process is promoted only by H.sub.2 gas.