Material and Generator for Generating Hydrogen Gas

Abstract

The invention is directed to a solid, porous material for generating hydrogen gas, said material having a porosity of 20 to 75 vol %, and a composition comprising, based on the weight of the material, 50 to 99% of a boron hydride compound, and 1 to 30% of a binder. A further aspect of the invention relates to a gas generator comprising said material and use thereof in aerospace applications.

Claims

1. A solid, porous material for generating hydrogen gas, said material having a porosity of 20 to 75 vol %, and a composition comprising, based on the weight of the material, 50 to 99% of a boron hydride compound, and 1 to 30% of a binder.

2. The material in accordance with claim 1, wherein said boron hydride compound is selected from the group consisting of ammonia borane, magnesium borane, sodium borohydride, lithium borohydride, and combinations thereof.

3. The material in accordance with claim 1, wherein the binder comprises an energetic binder.

4. The material in accordance with claim 1, wherein the binder comprises an inert binder.

5. The material in accordance with claim 1 that is essentially free of a compound or additive that directly on indirectly generates water upon reaction with the boron hydride compound.

6. The material in accordance with claim 1, further comprising an energizer.

7. A gas generator for generating hydrogen gas, comprising a housing for a gas generating material and an igniter, characterized in that the gas generating material comprises the solid, porous material of claim 1.

8. The gas generator according to claim 7, wherein upon operating of the gas generator, at least 90% of the generated gas passes through the solid, porous material.

9. An aerospace module comprising the gas generator according to claim 7.

10. The aerospace module in accordance with claim 9, wherein said gas generator comprises a vent for the generated gas, which vent is connected to an inflatable structure which is adapted such that upon inflation its outer surface area increases.

11. (canceled)

12. The material in accordance with claim 3, wherein the energetic binder is selected from the group consisting of polymers based on vinyltetrazole (PVT), polyvinyltetrazole and salts thereof, glycidyl azide polymer (GAP), poly(3-nitratomethyl-3-methyloxetane) (poly(NiMMo)), poly(glycidyl nitrate) (poly(GLyN)), and nitroxyethylnitramines (NENA).

13. The material in accordance with claim 3, wherein the energetic binder comprises alkyl nitroxyethylnitramine.

14. The material in accordance with claim 3, wherein the energetic binder is selected from the group consisting of ethyl nitroxyethylnitramine, n-butyl nitroxyethylnitramine (BuNENA) and nitro-hydroxyl terminated polybutadiene (NHTPB).

15. The material in accordance with claim 3, wherein the energetic binder comprises polyvinyltetrazole.

16. The material in accordance with claim 6, wherein the energizer comprises an ammonium halide.

17. The material in accordance with claim 6, wherein the energizer comprises ammonium chloride and/or ammonium fluoride.

18. The aerospace module of claim 9, wherein the aerospace module is a reentry shield for a landing device.

19. A method for increasing a surface area of a landing device, said method comprising generating hydrogen gas with the solid porous material according to claim 1 and inflating said device.

20. The method according to claim 21, wherein the landing device comprises a re-entry shield.

Description

[0025] It is to be noted that the following description is not limited to the specific embodiment of the figure, as this figure is presented mainly as an aid to understanding the invention and the preferred embodiments thereof.

[0026] The gas generator as illustrated in FIG. 1 contains an igniter (1), and one or more porous, gas generating charges (2). It is essential that this charge or charges are porous, allowing the decomposition gases to pass through this charge or these charges. Furthermore, the gas generator may contain one or more filters (3). The gas generator has a housing (4), a vent (5) and it may have a second igniter; this igniter is optional. Moreover the gas generator may have a neutralizing charge; this neutralizing charge is also optional. The neutralizing charge can for instance be used to neutralize or activate remaining species of the boron hydride compound that are not completely decomposed, turning these species into less harmful species or hydrogen gas such that the hydrogen gas production may even be increased.

[0027] The charge may have any suitable shape, be of a smaller diameter than the main charge or be perforated, although this is not preferred. Also layouts are possible where the neutralizing charge is ignited (with some delay) by the main igniter.

[0028] The igniter (1) ignites the main gas generating charge (2). The igniter can be of any suitable classical pyrotechnic type if there is no severe requirement on the purity of the gases that are delivered by the gas generator. The igniter may comprise an initiator, which may either be an electrical one, a percussion activated initiator or an initiator that is laser ignited.

[0029] The main gas generating charge may be of different shapes or may consist of stacks of charges of suitable shapes.

[0030] Each stack may also be of a different composition as to modify the decomposition rate or the composition of the gas, and/or the composition may vary over the length and or the width of the charge.

[0031] In the figure, the charges are cylindrical; this results in a rather constant mass flow rate of the produced gases. However, by making the charges in the shape of a (truncated) cone, two truncated cones, spherical or of other suitable shapes, the mass flow rate of gas may be pre-programmed for its specific application. The hot gas passes through the porous charge or charges, thereby exchanging its heat with the initial (virgin) cool charge material and cooling the gas.

[0032] The decomposition products may then be passed through a filter, after leaving the charge to purify the gas. A secondary function of the filter is to cool down the gas that is generated by the very last portion of the last porous charge.

[0033] The charges may be cast in the container but may also be cast separately and mounted in the housing later, optionally using a liner.

[0034] The layout of the gas generator is such that the decomposition gases always pass through the porous charge (2) thereby exchanging their heat with the main charge. Any bypassing of the charge is generally avoided, either by proper sealing, or because the charge is bonded or case-bonded to the housing or has a tight fit within the housing. This serves two purposes: the decomposition gases are cooled to ambient temperature, while the charge is heated to sustain the decomposition reaction.

[0035] The gas generator and the material can be used for various applications, including fuel cells and the delivery of energy, but it may particularly be suitable for applications in aerospace. For aerospace, the generated gas may for instance be used to inflate a device to increase the surface area thereof. It is envisioned that this can particularly be suitable for landing devices and decreasing the velocity thereof early upon entry in the atmosphere of an astronomical body such as a planet or moon. Currently, landing devices enter the earths atmosphere at high velocity with concomitantly high frictional forces which generate large amounts of heat. By increasing the outer surface area of the landing device, in particular a reentry shield thereof, early upon entry in the atmosphere, the velocity may be reduced in an early stage before the frictional forces result is such high heat formation. Due to the low atmospheric pressure at high altitude (for instance at 20 km altitude, the atmospheric pressure is about 5 pKa or lower), a relatively small mass of hydrogen gas can already provide a substantial volume and accompanying surface area.

[0036] Accordingly, a further aspect of the present invention is a aerospace module such as a breaking system, preferably suitable for an aerospace landing device. The vent can be connected to an inflatable structure which is adapted such that upon inflation its outer surface area increases.

[0037] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “and/or” includes any and all combinations of one or more of the associated listed items. It will be understood that the terms “comprises” and/or “comprising” specify the presence of stated features but do not preclude the presence or addition of one or more other features.

[0038] For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.