DE1909732A1 - Method and device for the production and storage of hydrogen - Google Patents

Description

lif -.- iNf ». W Os ■ ι. 'ί LlJi-Ji!

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P 19 09 752.6 Munich, July 8, 1969

Ar is id Victor Qrosse M / 9587

Method and device for the production and storage of hydrogen.

The present invention relates to the production and storage of hydrogen and, more particularly, relates to modes of operation and an apparatus for producing and storing hydrogen from a skid-loadable hydrogen gas generator.

A variety of sources of gaseous hydrogen are already known and the choice of a suitable source is known usually depends in part on the requirements of the system or apparatus in which the gas is used.

For example, hydrogen gas can be obtained by decomposing hydrides with water. The hydrogen evolved can then be used, for example, in a hydrogen / air fuel cell, which in turn provides the energy for an electrical device, for example

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ORJGINAL INSPECTED

the motor of a sump pump, as described in U.S. Patent 3,094,956.

Such a system can be useful if that Weight of reactants liberating hydrogen is of no concern, but has inherent disadvantages when weight is a major factor. For example, in a motor vehicle, in which a lithium hydride / water system is in a device for generating of hydrogen is used, about 72.5 kg of water and about 52 kg of lithium hydride are required to generate the energy or To deliver the fuel equivalent of about 76 liters (50 kg) of gasoline.

In addition, in hydride / water systems the hydride is decomposed in a rather complicated manner and instead of regeneration or recharging of the decomposed hydride through fresh hydride must be replaced.

Another disadvantage of hydride-water systems is that the reaction cannot be easily controlled. Hydrides in general, and hydrides containing aluminum in particular, react violently with water, causing the release evolved hydrogen and ignite if fairly arduous precautions are not taken.

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Hydrogen gas can also be obtained by thermal decomposition of hydrides, for example are described in the United States patent 2 890 519 gas ejection devices described, wherein hydrogen is evolved when the hydride is heated, and wherein hydrogen is rapidly absorbed, when the heating current is turned off. In this case the hydride is not irreversibly decomposed and the thermally decomposed one Hydride converts back to the original metal hydride in the last part of the cycle.

However, such gas ejecting devices do not consume the generated hydrogen. For this reason and because of her small size, such devices do not require as large an amount of hydrogen as they do for a Fuel cell is required when used as a power source for an electrical device, for example an engine in an electric automobile.

In addition, the weight of the hydrogen generator in a gas ejector is not of primary concern, Rather, the choice of a hydride is determined by its ability to readily evolve into hydrogen gas when heated to decompose and to form metal hydride again on cooling. For example, tantalum is in as a metal these devices have been used. However, it is

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necessary to transport about 179 kg of tantalum hydride, just to To be able to deliver 1 kg of hydrogen gas.

With this fact, the comparison with the delivery of hydrogen from pressure bottles does not even fall compressed hydrogen. If normal steel cylinders are used, they usually have to be by the kilogram available hydrogen about 100 to 150 kg container be transported.

Accordingly, the main aim of the present invention is to Working methods and a device for the controlled generation of hydrogen from certain metal hydrides too create, with the hydrogen being consumed while generating energy, the entire hydrogen generator benefits in terms of safety, reduced weight and minimal cost it offers and the exhausted generator with gaseous Hydrogen can be recharged or regenerated from an external source.

Other objects of the present invention will become apparent from the following detailed description clear.

The rechargeable or rechargeable according to the invention Hydrogen generator includes container assemblies,

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a contained mass of metal hydride bodies for heating at least a portion of the hydride to a decomposition temperature to generate the hydrogen gas and means for withdrawing the hydrogen from the container.

For regeneration or recharging of the hydrogen generator the decomposition products of the hydride remaining in the container become at suitable temperatures and printing subjected to the action of elemental hydrogen for a span sufficient to convert the decomposition products back into metal hydride.

The cycle of alternating production of hydrogen in the generator for hydrogen consuming energy purposes and then regenerating the decomposed hydride that remains in the container can be used an unlimited number of times be repeated.

In accordance with one feature of the present invention, daa Metal hydride thermally decomposes and gaseous hydrogen is generated, with a relative inside the container lower, but superatmospheric pressure is built up. The hydrogen is drawn from the container when required released through suitable valve devices. With suitable

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With the help of automatic regulating devices, the generator can operate automatically when the pressure is above atmospheric and is always ready for delivery.

To further facilitate the generation of hydrogen and the regeneration of the hydride, a finely divided Catalyst are distributed in the metal hydride.

The hydrogen generator according to the invention is particularly suitable for the delivery of hydrogen gas to a hydrogen consuming fuel cell to generate energy or To provide power for various transportation facilities, such as electric vehicles and Spacecraft that usually do not follow the paths that conventional transmission lines for electrical Energy are applied. In electrical power applications of the above type, the weight and size are System essential criteria. Electric vehicles have already found some application, however, one of the disadvantages has been the weight along with the price of the electrical power source in which it is conventionally to rechargeable electrical accumulators traded whose weight and price approach the weight or price of the vehicle.

Fuel cells in which substances such as hydrogen and oxygen or air are used as fuel are

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promising in this regard, however, the facilities for supplying hydrogen have so far had problems posed. For example, if gaseous hydrogen is provided in pressure cylinders, a container weighs containing 1 kg of hydrogen, more than 100 kg, is relatively expensive and requires certain precautionary measures the extraordinarily high pressure.

A characteristic feature of the water according to the invention to ff generators is that the hydrogen on demand is released and made available if it is used to feed the hydrogen-consuming energy source, for example a fuel cell is required. For example, if the fuel cell is in an electric Motor vehicle is used, so not only can it start quickly, but it also provides a full charge during starting and while idling when the vehicle is stationary, for example at traffic lights.

Another important feature of the present invention resides in the fact that the hydrogen generator again can be charged or recharged. It can be regenerated while it is still in the vehicle, or, perhaps preferably, it can be removed from the vehicle and replaced with a new container, the removed container then being processed to regenerate the hydride. - 8th ·

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The invention is explained below with reference to the drawings. Show:

Figure 1 is a partially sectioned, perspective view of the hydrogen generator according to the invention,

Figure 2 is a schematic view of a movable energy delivery device according to the invention, wherein the hydrogen generator and a fuel cell are shown, and

Figure 3 is a schematic view of an electric motor vehicle, wherein the energy unit is a fuel cell and a hydrogen according to the invention generator for storage and release of hydrogen includes.

Preferred embodiments of the invention are described below.

The hydride used can be solid, liquid, or a combination of liquid and solid hydrides in a weight ratio of available hydrogen and hydride of at least about 1:15. Preferably the weight ratio is above about 1: 7 In other words, about 15 kg, preferably about 7 kg, initial metal hydride should release about 1 kg of hydrogen gas when heated.

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For example, lithium aluminum hydride releases its hydrogen when heated to temperatures of about 150 to 283 ⁰ C according to the following equation:

Li

AlH ₁

LiH + Al + 1.5 H ₂

1 kg of hydrogen can thus be released from approximately 12.7 kg of lithium aluminum hydride. The hydrogen in the lithium hydride LiH formed according to the above equation is released at temperatures of approximately 400 ^° C. and higher. This reaction is therefore not normally carried out in order to complete the liberation of all the possible hydrogen available.

In the case of liquid aluminum borohydride, the weight ratio is more favorable, and its thermal decomposition takes place at temperatures from about 100 to about 150 ° C according to the following equation takes place:

Al

BHi

Al + 5B + 6H ₂

1 kg of hydrogen can thus be released from around 6.5 kg of aluminum borohydride.

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Representative solid hydrides that are useful are the Aluminum-containing hydrides such as the alkali metal aluminum hydrides, alkaline earth metal aluminum hydrides, aluminum hydrides and their Lewis base complexes. Particularly preferred are sodium aluminum hydride, lithium aluminum hydride, beryllium aluminum hydride, magnesium aluminum hydride and Calcium aluminum hydride.

Various Lewis base complexes of aluminum hydrides can also be used, for example the Etherate of diethyl ether.

Other suitable solid hydrides include the borohydride complex of lithium aluminum hydrides and the ammonium complex of borohydride.

Suitable liquid hydrides include aluminum borohydride.

The chemistry of these compounds has already been described in a number of publications and is therefore needed here not to be discussed further.

A suitable combination of the above liquid and solid hydrides is lithium hydride impregnated with the aluminum borohydride. For example, the solid lithium aluminum hydride can be mixed with liquid aluminum borohydride in amounts of about JO to 70 Oew.-Ji can be impregnated. - 11 -

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The choice of a suitable hydride is usually made based on part by weight considerations as well as by considerations regarding the thermal decomposition conditions of the hydride. For example, the use of the hydrides described above will normally allow the generation of hydrogen at temperatures from about IGO to 300 ° C and at

2
Print from about 0.7 to 5.3 kg / cm (10 to 75 psi).

The solid aluminum containing hydrides, for example | Lithium aluminum hydride, can be prepared or obtained commercially as salt-like white solids, usually in powder form. The bulk of the solid hydride should be sufficiently porous to allow the generated hydrogen to escape from the bulk and to allow the regenerating hydrogen to penetrate or disperse during regeneration. For example, the hydride should have an average porosity of about 3 to 12 % by volume. One way of ensuring uniform porosity and thus high levels of performance is to convert the solid hydride into particulate form, as is described, for example, in US Pat. No. 3,222,122.

Binders may be required to ensure that the particles do not crumble or fall apart. Binder, such as other hydrides, particularly magnesium and calcium hydrides, are in amounts of about

2 to 12 VoI.-Ji suitable. - 12 - '

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Another way to achieve the desired porosity consists in the internal construction of the container, as described in detail below.

To further accelerate the generation of hydrogen from the hydrides, catalysts can be distributed in the hydrides will. These catalysts are also in the relatively easy and smooth regeneration of the thermally decomposed Materials back to the hydride matter.

Representative metal catalysts that are useful are the Group VIII metals, including iron, cobalt, nickel, palladium, platinum, rhodium, iridium, osmium, and ruthenium. The catalysts containing iron, cobalt and nickel are particularly preferred. Gold, silver and copper can also be used individually or in combination or with the Group VIII metals mentioned above. The catalysts can be distributed in the hydrides as finely divided material in an amount of about 0.001 to about 1.0% by weight , preferably in an amount of about 0.01 to about 0.1% by weight.

Carrier for the catalyst, such as aluminum wire or magnesium tape, can also be present.

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Regeneration of the thermally decomposed hydride can be achieved by subjecting the decomposed material to hydrogen pressure under conditions suitable for conversion back to hydride. For example, the decomposed material at Tempe & structures can of about ⁰ to 250 C and at hydrogen pressures from about 5.25 to

kg / cm (75 to 2000 psi) regenerated to its hydride form.

Such hydride-generating processes are known and need not be described in detail. Example game system 1st from British patent specification 972 076 a process for the production of metal aluminum hydrides known in which a metal hydride is reacted with aluminum and hydrogen under pressure. In collection Czechoslov. Chem. Commun. ^ 2 is on pages 884 through 891 describes a process for the production of sodium aluminum hydride from aluminum, sodium and hydrogen gas.

The hydrogen is released by the hydrides In a container strong enough to withstand the maximum pressures envisaged is heated, for example by electrical resistance heating.

The container can have any shape, for example be cylindrical, spherical, or box-like. For example, it can be made small enough to accommodate

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a person to be transported, or it can be large enough to accommodate a hydrogen-consuming automobile to supply, or it can be used for energy supply of a building can also be bigger.

Oa this container does not have to withstand the extremely high pressures that occur in cylinders for pressurized gases, it can be made from thin steel or stainless steel or light metal such as aluminum, magnesium, beryllium and their alloys, which weight forms part of the total weight of the hydrogen generator. If aluminum is used as a container material, it may be necessary, for example, with a thin Layer of aluminum oxide is coated to prevent reaction with the hydrogen gas.

A container with a capacity of about 565 liters. (20 cubis feet) can hold approximately 454 kg (100 pounds) of aluminum hydride, which when heated is approximately 36.3 kg (80 pounds) Generating hydrogen, which is equivalent to the energy required by about 90.7 kg (200 pounds), that is about 132 liters. (35 gallons) of gasoline is dispensed.

Appropriate connections and valves for withdrawing hydrogen can be provided on the container, and it can the same or a separate connection can be used in the regeneration of the decomposed hydride. - 15

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The container can also be equipped with a pressure equalization or safety valve be provided in order to avoid an accidental pressure build-up in the container. The hydrogen can be in the atmosphere can be vented.

The internal construction of the container can vary depending on the hydride used, the amount of hydrogen required and other factors such as strength requirements can be varied.

According to FIG. 1, bundles of coaxial cylinders jj can be present in the interior 2 of the container 1, with electrical cylinders as shown Heating elements 4 are arranged along the walls of the cylinder or, alternatively, the walls as the electrical resistance heating element can serve. The heating elements 4 can successively through the switching relay 8, which is shown schematically in FIG.

These coaxial cylinders 5 can have perforations 7, to allow hydrogen to exit through them and through the exit valve or port 5. These Perforations also allow hydrogen to return to regenerate the material 6 contained therein.

At V _e of such coaxial cylinders rwendung the desired porosity of the free space can be obtained. Al-

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Alternatively, the interior of the container can consist of a stack of rectangular or differently shaped polygonal boxes exist. Again, electrical heating elements can be placed in, around, or through the whole.

According to another embodiment, not shown, can the hydride can be contained in small porous spheres or smaller containers of other shapes that form the outer container 1 and ensure high efficiency, as the hydrogen gas can move freely through the container.

In this way, the internal structure of the container prevents it Channel formation and compaction of the solid hydride, which the Would reduce efficiency. Of course, in many cases the porosity of the hydride can be sufficient, and it can eliminate any need for special considerations in container design.

W When liquid hydrides are used, the internal structure of the generator can provide a plurality of heating surfaces to cover the liquid hydride as a film or coating, thereby achieving high heating efficiency.

The tank can also be equipped with automatic pressure regulators, for example valves, compressors and the like, are provided so that there is always a supply of gaseous hydrogen is available. For example, can

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at pressures of about 2.11 to 4.22 kg / cm ² (? 0 to 60 psi) reserve hydrogen in amounts of about 14.1 to 56.6 liters (1/2 to 2 cubic feet) will be suitable. In conjunction with this, an additional reservoir or container can be used to store the reserve hydrogen.

The hydrogen generator can be used to supply hydrogen used in any convenient location, but is particularly suitable for use in connection with fuel cells in electric vehicles.

In Figure 2, a movable electrical generator device 10 is illustrated, which schematically shows a fuel cell 11 together with the hydrogen generator 12, which supplies the required hydrogen through line 13 and valve device 14, which is regulated by the demand of the fuel cell 11.

In the generator 12, a superatmospheric hydrogen pressure can be maintained to the cell 11 with To bark hydrogen until the cell 11 generates sufficient energy to generate the hydride contained in the generator to be heated via the transmission line 15. Alternatively A small electrical accumulator (not shown) can be provided to generate the initial energy for heating of the generator 12 to deliver.

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The motor vehicle 20 illustrated in Figure 3 is of the conventional type having one or more wheels driven by electric motors. Examples of such electric motor vehicles are described in U.S. Patents 2,208,710 and J> 182 7 ^ 2.

In the illustrated vehicle 20, a number of fuel cells 21 provide power for the electric motors 22. Currently available fuel cells have a power output on the order of lKllowatts and may be ten or more such fuel cells can be used to create the energy source for the motor vehicle.

The hydrogen generator 25 can be at any suitable location of the vehicle can be located, for example in the rear compartment 22. Line 24 connects the hydrogen generator 25 to the inlet of the fuel cell 21. Again, a valve device 26 is provided, which is regulated by the demand of the fuel cell 21. A. electric accumulator 27 is provided to supply the generator with the initial heating energy.

The embodiments of the present invention described above are only intended to illustrate this, but not limit.

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Claims (1)

Claims 1. A process for the production and storage of hydrogen, characterized in that a metal hydride with a weight ratio of hydrogen to hydride of at least about 1:15 is introduced into a container and the hydride is brought to a decomposition temperature heated to generate hydrogen gas, the hydrogen gas supplies a power source consuming hydrogen with energy generation and the decomposition products of the hydride that remain in the container at a temperature of about 140 to about 250 ⁰ C and at a pressure of about 5.25 to subjecting approximately 14 l kg / cm (75 to 2000 psi) to elemental hydrogen for a period of time sufficient to convert the decomposition products back to metal hydride. 2. The method according to claim 1, characterized that one can cycle the alternating production of hydrogen from the container for energy purposes and regenerating the decomposition products of hydride remaining in the container at least once repeated. - 20 009808 / U69 5 · Rechargeable hydrogen generator as a device for carrying out the method according to claims 1 and 2, characterized by container devices, a mass of metal hydride contained therein, the hydride having a weight ratio of available hydrogen to hydride of at least about 1:15, facilities for heating at least a portion of the hydride to a decomposition temperature, thereby producing hydrogen, and means for the escape of hydrogen from the container. 4. Apparatus according to claim 3, characterized in that the hydride has an average Has porosity from about 3 to about 12 volume #. 5. Device according to claim 4, characterized in that the hydride is in particulate form. 6. Apparatus according to claim ~ $, characterized in that the hydride is an aluminum-containing hydride. 7. Apparatus according to claim 6, characterized in that the aluminum-containing hydride among alkali metal aluminum hydrides, alkaline earth metal aluminum hydrides, Aluminum hydrides and Lewis base complexes of these hydrides is selected. - 21 - 009808 / U69 8. Apparatus according to claim 7, characterized in that the aluminum-containing hydride Is lithium aluminum hydride. 9 · Device according to claim 2, characterized in that the mass of the metal hydride solid metal hydride "impregnated with a liquid hydride. 10. Apparatus according to claim 9, characterized in that the liquid hydride is aluminum borohydride. 11. The device according to claim 3, characterized in that a finely divided metal catalyst is distributed in the hydride in order to accelerate the hydrogen production. 12. The device according to claim 11, characterized in that the finely divided metal catalyst is selected from catalysts containing iron, cobalt and nickel. 13. The device according to claim 3, characterized in that the heating devices preferably heat the hydride. 009808 / U69 BATH ORIGINAL Blank page