Oxygen generator using ionic liquids

Abstract

The invention relates to a device for generating oxygen, comprising at least one reaction chamber for housing a composition for generating oxygen, the composition comprising an oxygen source formulation and a ionic liquid formulation, the oxygen source formulation comprising a peroxide compound, and the ionic liquid formulation comprising a ionic liquid having a cation and a metallate anion, means for maintaining the oxygen source formulation and the ionic liquid formulation physically separated from each other, means for establishing physical contact of the oxygen source formulation and the ionic liquid formulation, and means for allowing oxygen to exit the reaction chamber.

Claims

1. A device for generating oxygen, comprising at least one reaction chamber; a composition for generating breathable oxygen contained in the housing, the composition comprising an oxygen source formulation and an ionic liquid formulation, the oxygen source formulation comprising a peroxide compound, and the ionic liquid formulation comprising an ionic liquid having a cation and a metallize anion, means for maintaining the oxygen source formulation and the ionic liquid formulation physically separated from each other, means for establishing physical contact of the oxygen source formulation and the ionic liquid formulation, and means for allowing oxygen to exit the reaction chamber, wherein the oxygen source formulation and the ionic liquid formulation, upon coming into contact with one another, generate breathable oxygen.

2. The device according to claim 1, wherein the means for allowing oxygen to exit the reaction chamber is a gas permeable membrane or a frit, which is gas permeable and liquid tight.

3. The device according to claim 1, wherein the reaction chamber comprises a first compartment for receiving one of the oxygen source formulation and the ionic liquid formulation and a second compartment for receiving the other one of the oxygen source formulation and the ionic liquid formulation.

4. The device according to claim 1, wherein the means for maintaining the oxygen source formulation and the ionic liquid formulation physically separated comprise at least one receptacle within the chamber for receiving one of the oxygen source formulation and the ionic liquid formulation, or comprise a membrane, a metal or plastic foil, or a glass sheet between the first compartment and the second compartment.

5. The device according to claim 1, wherein the means for establishing physical contact comprise a dosing mechanism or a device for destroying the means for maintaining the oxygen source formulation and the ionic liquid formulation physically separated, and an activation mechanism for activating the device or the dosing mechanism.

6. The device according to claim 5, wherein the device for destroying is a solid plate, a grid, a cutting edge, or a firing pin.

7. The device according to claim 1, wherein the at least one reaction chamber is placed within a container having an oxygen outlet.

8. The device according to claim 1, wherein at least two reaction chambers, or from 3 to 20 reaction chambers, are placed within in a container having an oxygen outlet, the container providing a common gas space for receiving oxygen exiting the at least two or from 3 to 20 reaction chambers.

9. The device according to claim 8, wherein the composition for generating oxygen includes two different compositions for generating oxygen disposed in two reaction chambers, wherein the different compositions for generating oxygen differ either in a type of ionic liquid having a metallate anion or in a type of peroxide compound, or in a degree of compaction of the oxygen source.

10. The device according to claim 1, wherein the peroxide compound is selected from alkali metal percarbonates, alkali metal perborates, urea hydrogen peroxide, and mixtures thereof.

11. The device according to claim 1, wherein the cation is selected from the group consisting of heterocyclic hydrocarbon cations, ammonium and phosphonium cations.

12. The device according to claim 1, wherein the ionic liquid formulation also comprises an ionic liquid not having a metallate anion.

13. The device according to claim 1, wherein the metallate anion comprises at least one transition metal and at least one halide ion and/or pseudohalide ion.

14. The device according to claim 7, wherein the oxygen outlet is configured for restricting gas flow therethrough.

15. A charge component for a device for generating breathable oxygen, the charge component comprising an oxygen formulation comprising a peroxide compound and an ionic liquid formulation comprising an ionic liquid having a cation and a metallate anion, and wherein the oxygen source formulation and the ionic liquid formulation, upon coming into contact with one another, generate breathable oxygen for human breathing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be further illustrated by the following non limiting examples with reference to the accompanying drawings, wherein:

(2) FIGS. 1 to 3 are graphs illustrating oxygen evolution from UHP with different ionic liquid formulations.

(3) FIG. 4 is a graph illustrating oxygen evolution from different peroxide compounds with C4mim Fe CI4,

(4) FIG. 5 is a graph illustrating reaction temperatures of reactions of UHP with different ionic liquids,

(5) FIG. 6 is a graph illustrating reaction temperatures during decomposition of different amounts of UHP,

(6) FIG. 7 is a graph illustrating oxygen evolution from powder compacts as compared to powder,

(7) FIG. 8 is a graph illustrating oxygen evolution from different amounts of peroxide compacts, having different weight at an equivalent compaction pressure.

(8) FIG. 9 is a graph illustrating oxygen evolution from peroxide powder compacts having different shapes,

(9) FIG. 10 is a graph illustrating oxygen evolution from different peroxide compounds,

(10) FIG. 11 is a graph illustrating oxygen evolution from peroxide powder compounds having different particle sizes before compacting,

(11) FIGS. 12 to 16 schematically illustrate several embodiments of devices for generating oxygen from compositions according to this invention,

(12) FIGS. 17 and 18 are graphs illustrating oxygen evolution from devices having several reaction chambers, and

(13) FIG. 19 is a graph illustrating peak reaction temperatures for each reaction chamber of the device illustrated in FIG. 18.

DETAILED DESCRIPTION

(14) In all graphs illustrating oxygen evolution or reaction temperature, oxygen evolution (or reaction temperature, respectively) is plotted against runtime, wherein runtime is the time which starts running at the time point of contacting the oxygen source and the ionic liquid.

(15) In the following examples, a drum gas meter having a simple voltage pick-up, and an analog-digital-converter was used for measuring the oxygen volume which was generated by the peroxide decomposition reaction. This resulted in a systematic measurement error. In many examples, the gas volume which was measured, was somewhat higher than the theoretically possible gas volume. The reason is that the decomposition reaction is slightly exothermic, somewhat heating up the oxygen generated to a temperature somewhat above room temperature. When the oxygen exits the reaction chamber, it is cooled down to room temperature, leading to contraction of the gas volume. The drum gas meter used could not compensate the volume errors due to contraction of the gas volume upon cooling down. Rather, the negative volume (volume decrease) was registered as a positive volume (volume increase). The value of 0.131000 cm3 indicated in some of the Figures corresponds to the theoretical amount of releasable O2.

(16) In the examples, the following abbreviations are used

(17) ##STR00002## IL: ionic liquid UHP: urea hydrogen peroxide

EXAMPLE 1

(18) 10.0 mmol urea hydrogen peroxide (UHP) and 10.0 mmol of different imidazolium tetrachloroferrates are charged into a round bottom flask. After closing the vessel, the oxygen volume released is measured with a drum gas meter. Charged amounts and volume of gases released are indicated for different active ionic liquids in table 1.

(19) TABLE-US-00001 TABLE 1 Charged amounts and volume of oxygen released for reactions of different imidazolium tetrachlorferrates and 1 g UHP. ionic liquid C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 C.sub.6mimFeCl.sub.4 C.sub.8mimFeCl.sub.4 mass UHP 1 g 1 g 1 g 1 g mass IL 3.10 g 3.36 g 3.65 g 3.93 g gas 132.5 cm.sup.3 135 cm.sup.3 135 cm.sup.3 165 cm.sup.3 volume

(20) The reaction profile is shown in FIG. 1. FIG. 1 shows that the onset of the decomposition reaction strongly depends on the particular ionic liquid used.

EXAMPLE 2

(21) 10.0 mmol urea hydrogen peroxide (UHP) each are charged into a vessel together with ionic liquid formulations as indicated in table 2. After closing the vessel, the gas volume released is measured. The results are illustrated in table 2 and FIG. 2.

(22) TABLE-US-00002 TABLE 2 Charged amounts and volumes of gases released for reactions of different ionic liquid formulations with 1 g UHP. IL-formulation 6% solution of C.sub.4mimCuCl.sub.2 C.sub.4mimFe(III)Cl.sub.4:C.sub.6mim.sub.2Fe(II)Cl.sub.4 C.sub.4mimCuCl.sub.2 in C.sub.4mimTFSI C.sub.6mim.sub.2Fe(II)Cl.sub.4 1:1 (molar) amount UHP 1 g 1 g 1 g 1 g amount IL 2.73 g 2.69 g 5.32 g 4.34 g gas volume 150 cm.sup.3 113 cm.sup.3 120 cm.sup.3 108 cm.sup.3

(23) Table 2 and FIG. 2 show that the amounts of oxygen released are similar for different ionic liquids, however, the onset of the decomposition reaction varies considerably for different ionic liquid formulations.

EXAMPLE 3

(24) 10 mmol UHP and 10 mmol of different imidazolium tetrahaloferrates are charged into a round bottom flask. The particular ionic liquids used are indicated in table 3. After closing the vessel, the gas volume released were measured with a drum gas meter. Charged amounts and volumes of gases released by the different ionic liquids are also indicated in table 3.

(25) TABLE-US-00003 TABLE 3 Charged amounts and gas volumes released for reactions of different imidazolium tetrahaloferrates and 1 g UHP. IL formulation C.sub.4mimFeBr.sub.4 C.sub.4mimFeBrCl.sub.3 C.sub.4mimFeCl.sub.4 amount UHP 1 g 1 g 1 g amount IL 5.15 g 3.81 g 3.36 g gas volume 128 cm.sup.3 128 cm.sup.3 135 cm.sup.3

(26) As table 3 and FIG. 3 show, the oxygen volumes released are very similar for the different tetrahaloferrates, however, the time point of onset of the decomposition reaction differs considerably for the different tetrahaloferrates.

EXAMPLE 4

(27) 10 mmol hydrogen peroxide adduct compounds as indicated in table 4 and 10 mmol C.sub.4mim Fe Cl.sub.4 are charged into a round bottom flask. After closing the vessel, the gas volume released is measured with a drum gas meter. Charged amounts and volumes of oxygen released from different peroxides are shown in table 4 and FIG. 4.

(28) It can be seen that different peroxide compounds, and also mixtures of peroxide compounds, are effective for producing oxygen.

(29) TABLE-US-00004 TABLE 4 sodiumper- peroxide sodiumper- sodiumper- borate:UHP 1:1 adduct carbonate borate UHP (molar) amount 1.5 g 1.54 g 1 g 1.25 g peroxide amount IL 3.36 g 3.36 g 3.36 g 3.36 g gas volume 128 cm.sup.3 128 cm.sup.3 133 cm.sup.3 135 cm.sup.3

EXAMPLE 5

(30) 10 mmol UHP and 10 mmol active ionic liquid as indicated in table 5 are charged into a round bottom flask. After closing the vessel the oxygen volume released is measured by a drum gas meter. Simultaneously, the temperature of the reaction solution is measured with a thermocouple (K-type). The maximum temperatures measured are listed in table 5 and shown in FIG. 5. It can be seen that the peak temperatures are different for different ionic liquids, however, peak temperatures are always low. Even the highest peak temperature is below 120 C.

(31) TABLE-US-00005 TABLE 5 Maximum reaction temperature for different ionic liquids when decomposing 1 g UHP IL maximum temperature C.sub.2OHmimFeCl.sub.4 79 C. C.sub.4mimCuCl.sub.2 81 C. C.sub.4imFeBr.sub.4 119 C. C.sub.4mimFeCl.sub.4 57 C.

EXAMPLE 6

(32) Different amounts of urea hydrogenperoxide (UHP) and equimolar amounts of C4mim Fe Cl.sub.4 are charged into a round bottom flask. After closing the vessel, the gas volume released is measured with a drum gas meter, and simultaneously the temperature in the reaction solution is measured with a thermocouple (K-type).

(33) The maximum temperatures measured and the volumes of gas released are listed in table 6. The maximum temperatures are also shown FIG. 6.

(34) TABLE-US-00006 TABLE 6 Maximum reaction temperature for different ionic liquids when decomposing 1 g UHP. amount UHP gas volume released maximum temperature 1 g UHP 140 cm.sup.3 79 C. 5 g UHP 545 cm.sup.3 81 C. 10 g UHP 1388 cm.sup.3 119

(35) As table 6 and FIG. 6 show, the maximum temperatures increase with increasing amounts of peroxide. However, in all cases, the reaction temperatures are below 120 C.

EXAMPLE 7

(36) 1 g urea hydrogen peroxide adduct compound (UHP) in powder form or compressed into a pellet (cylindrical mold) or compressed into a cube, was added in a glass flask with an imidazoliumferrat-based ionic liquid formulation (C4mimFeCl4) having peroxide decomposing capability. After closing the reaction vessel, the oxygen volume released is measured with a drum gas meter. Compression pressures, oxygen released and time till complete release of the available oxygen are listed in table 7. FIG. 7 depicts the oxygen volume released versus reaction time for the UHP powder compacts (pellets) and the UHP powder.

(37) The results clearly prove that in the case of an oxygen source in powder form, the decomposition reaction of the oxygen source starts quite promptly after combining the oxygen source and the active ionic liquid, whereas in the case of an oxygen source in compressed form, the onset of the decomposition reaction is somewhat delayed. FIG. 8 illustrates a comparison of the oxygen evolution of different mold geometries for peroxide powder compacts of identical compression.

(38) FIG. 8 compares the decomposition reaction profiles of squared powder compacts and round powder compacts. The powder compacts have the same degree of compression. Obviously, the different geometries do not influence the decomposition reaction profile. Rather reaction rate on onset of the reaction, and volume of oxygen released are very similar for the squared and the round powder compact.

(39) TABLE-US-00007 TABLE 7 peroxide compaction adduct (shape) mass pressure volume Time .sup.1 UHP (powder) 1 g 133 cm.sup.3 2.2 min UHP (pellet) 1 g 75 MPa 135 cm.sup.3 8.4 min UHP (squared) 1 g 74 MPa 142 cm.sup.3 8.1 min .sup.1 time means time till complete release of all available oxygen.

EXAMPLE 8

(40) Different amounts of urea hydrogen peroxide compound compressed into pellets (round shape) were admixed in a glass flask with an imidazoliumferrate based ionic liquid formulation (C.sub.4mim Fe Cl.sub.4) having peroxide decomposing capability. After closing the reaction vessel, the gas volume released is measured with a drum gas meter. Likewise, an oxygen source, composed of UHP and sodium perborate (molar ratio 1:3) was treated in the same manner. Peroxide amounts, compaction pressure, volume of gas released, and time till complete release of the available oxygen are listed in table 8. Oxygen generation for the urea hydrogen peroxide pellets (the pellets having different diameters due to different amounts of UHP) versus reaction time is depicted in FIG. 9. FIG. 10 depicts oxygen generation from pellets of mixed peroxide adduct (UHP: sodium perborate, molar ratio 1:3).

(41) TABLE-US-00008 TABLE 8 peroxide compaction adduct (shape) mass pressure volume time.sup.1 UHP (Pellet) 1 g 75 MPa 140 cm.sup.3 5.5 min UHP (Pellet) 5 g 75 MPa 550 cm.sup.3 6.1 min UHP (Pellet) 10 g 75 MPa 1100 cm.sup.3 6.1 min UHP:Sodium 10.9 g 75 MPa 1165 cm.sup.3 5.5 min perborate 1:3 (molar) (pellet) .sup.1time means time till complete release of all available oxygen

(42) FIG. 11 depicts a comparison of the oxygen release from the pellet having a mass of 1 g, comparing pellets made from UHP powder with different particle sizes.

(43) It can be seen from FIG. 9 that the amount of peroxide used determines the amount of oxygen generated. The reaction rate and the time of onset of the decomposition reaction are not significantly influenced by the amount of the peroxide used.

(44) FIG. 10 illustrates that the oxygen generation from urea hydrogen peroxide as the sole oxygen source is similar to the oxygen generation from a mixed oxygen source comprising UHP and sodium perborate. The particular oxygen source has little influence on the amount of oxygen generated, the reaction rate, and the onset of the decomposition reaction.

(45) While the degree of compaction, i.e. the compaction pressure, significantly influences the time point of the onset of the decomposition reaction, particle sizes before compaction do not play a role. This is evident from FIG. 11, comparing oxygen generation from UHP pellets of equal weight, which had been pressed with the same compaction pressure. One example, however, had been milled into very fine particles before compression. Nevertheless, the reaction profile is nearly identical for both samples.

(46) In exemplary embodiments, a device for generating oxygen from compositions as described above which uses ionic liquids having metallate anions for decomposing a peroxide compound as an oxygen source, and for dissipating reaction heat generated during the decomposition reaction, is specifically designed. A device for generating oxygen, in exemplary embodiments, has at least one reaction chamber for storing the composition in a condition where the oxygen source and the active ionic liquid are not in physical contact with each other. Such physical contact of the oxygen source and the active ionic liquid must be established at the very moment when oxygen is required. In exemplary embodiments, the device is equipped with suitable means for allowing the oxygen source and the active ionic liquid to contact each other at that very moment. Furthermore, in exemplary embodiments the device allows that the generated oxygen exits the reaction chamber. Some exemplary devices are illustrated in FIGS. 12 to 16, wherein like reference numerals designate like components. The description of such exemplary embodiments shall not be construed as limiting the invention in any manner.

(47) FIG. 12 illustrates a device 1 for generating oxygen having one single reaction chamber 2 for storing the composition for generating oxygen. In such a single reaction chamber 2 at least one of the oxygen source and the active ionic liquid is enclosed in a receptacle in order to avoid contact with the respective other constituent contained in the reaction chamber 2. In the embodiment shown in FIG. 12, two receptacles 5, 6 are arranged in the reaction chamber. Receptacle 5 contains the oxygen source formulation 7, for example in powder form or compressed into pellets. Receptacle 6 contains an ionic liquid formulation 8. Alternatively, there may be only one receptacle for enclosing the oxygen source formulation, while the ionic liquid formulation is free within reaction chamber 2, or ionic liquid formulation 8 may be enclosed within a receptacle, while the oxygen source formulation 7 is not enclosed in a separate receptacle.

(48) Herein, the term oxygen source formulation means that the oxygen source may be one single peroxide compound, but may be as well a combination of two or more peroxide compounds, and may optionally contain any additives not detrimentally interacting with the peroxide decomposition reaction.

(49) The term ionic liquid formulation as used herein indicates that the ionic liquid may be one single active ionic liquid as described above, but may be as well a combination of two or more active ionic liquids as described above, or may be diluted by one or several different non active ionic liquids. Furthermore, the ionic liquid formulation may contain any additives not detrimentally interacting with the peroxide decomposition reaction.

(50) It is desirable to store the oxygen source formulation 7 and the ionic liquid formulation 8 within the reaction chamber 2 in such an arrangement that the oxygen source formulation and the ionic liquid formulation will be able to get intimately mixed once oxygen generations is required. On the other hand, untimely mixing shall be avoided. Therefore, in the exemplary embodiments both the oxygen source formulation and the ionic liquid formulation are placed in a receptacle each. This constitutes an advantageous precautionary measure against accidental mixing of the oxygen source and the active ionic liquid in case of receptacle leakage or breakage.

(51) In a situation where oxygen shall be generated, receptacle 5, or receptacles 5 and 6, respectively, are destroyed by a breaking device 18. In FIG. 12, breaking device 18 has the form of a plate, however, means for destroying the receptacle(s) are not limited to plates, and other means are known to persons skilled in the art, for example firing pins or grids. Movement of plate 18 can be achieved by a spring 19 or another activation mechanism. During storage of the device for generating oxygen, spring 19 is under tension and holds plate 18 at a position distant from receptacles 5, 6. Once the tension is released by a suitable trigger mechanism (not shown), spring 19 moves plate 18 towards receptacles 5, 6, and plate 18 destroys receptacles 5, 6. Such a trigger may be, for example, pulling an oxygen mask towards a passenger in an air plane. Another exemplary trigger mechanism is an oxygen sensor sensing a low oxygen condition.

(52) Receptacles 5, 6, and plate 18 are made from materials which guarantee that receptacles 5, 6 will be broken or ruptured when hit by plate 18. Exemplary materials are plastic foils or glass for receptacles 5, 6, and thicker plastic material or metal for plate 18.

(53) Destruction of receptacles 5, 6 causes mixing of the oxygen source formulation 7 and the ionic liquid formulation 8, and initiates oxygen generation already at room temperature or temperatures below room temperature. In order to allow that the oxygen exits reaction chamber 2, reaction chamber 2 has an opening which is sealed, in the illustrated embodiment, with a gas permeable membrane 16. The opening may be at a different position than shown in FIG. 12, or there may be more than one opening. This applies analogously to all devices for generating oxygen of this invention.

(54) The oxygen generated in the devices of this invention may be passed through a filter or other purification means as known in the art. The devices may be equipped with such means.

(55) The oxygen generating reaction is an only slightly exothermic process, and reaction heat generated by the decomposition process does not considerably heat up the oxygen generated. Oxygen exiting the reaction chamber is nearly at a temperature suitable for breathing, i.e. well below 150 C. Reaction chamber 2 does not need to resist high temperatures, and maybe made from lightweight, low melting materials such as plastic. In addition, any bulky insulation is not required. This is particularly advantageous in all cases where weight must be saved and/or space is limited, for example in the case of oxygen masks which shall be installed in an aircraft.

(56) FIG. 13 illustrates an alternative embodiment of an inventive device 1 for generating oxygen. In the embodiment of FIG. 13, the reaction chamber 2 has two compartments, a first compartment 3 and a second compartment 4, which are separated by a liquid tight membrane 17. The first compartment 3 contains the oxygen source formulation 7, and is equipped with a cutting device 20 having a cutting edge 20. The cutting device is arranged in a position that allows cutting edge 20 to cut through membrane 17 separating the first compartment 3 and the second compartment 4.

(57) Compartments 3, 4 have openings sealed by membranes 15, 16, respectively. Membranes 15, 16 are gas permeable, thus allowing the oxygen generated during the oxygen generating reaction to exit reaction chamber 2.

(58) An activation mechanism 19, for example a spring, is provided for moving cutting edge 20 towards membrane 17, and through membrane 17. Such a mechanism is described in DE 10 2009 041 065 A1. As explained in connection with FIG. 12, spring 19 is under tension during storage of device 1, and once the tension is released by a trigger mechanism (not shown), spring 19 moves the cutting device towards membrane 17, cutting edge 20 destroys membrane 17, and first compartment 3 and second compartment 4 are combined into one single reaction chamber 2.

(59) In the embodiment illustrated in FIG. 13, oxygen source formulation 7 is contained in the first compartment 3, and ionic liquid formulation 8 is contained in second compartment 4. Upon destruction of membrane 17, oxygen source formulation 7 drops into second compartment 4, and mixes with ionic liquid formulation 8. The oxygen generated exits the reaction chamber 2 through membranes 15, 16.

(60) Of course, it is also possible to place ionic liquid formulation 8 into the first compartment 3 and oxygen source formulation 7 into the second compartment 4.

(61) As a material for cutting device 20, any material may be used which may cut membrane 17, for example a metal sheet. The first compartment 3 and the second compartment 4 can be formed from the same materials as the single reaction chamber 2 illustrated in FIG. 12.

(62) Another embodiment of an inventive device 1 for generating oxygen is illustrated in FIG. 14. In the embodiment of FIG. 14, reaction chamber 2 is equipped with an injection device 21, for example a syringe, or another dosing device.

(63) Reaction chamber 2 and injection device 21 are connected, or constitute separate units which can be connected to form one single unit. An opening, or several openings, in the wall of reaction chamber 2 allow that oxygen generated during the peroxide decomposition reaction exits reaction chamber 2. The openings are sealed, in the illustrated embodiment, by gas permeable membranes 16. In the embodiment illustrated in FIG. 14, the openings are provided at the junction of reaction chamber 2 and injection device 21.

(64) The exemplary injection device of FIG. 14 comprises a slide bar 22, a spike 23, and an injection lance 24. The injection device is adapted for holding the oxygen source formulation 7 or the ionic liquid formulation 8, in the illustrated example the ionic liquid formulation 8. Ionic liquid formulation 8 is contained in a receptacle 5, made from a material which can be easily ruptured, for example a plastic foil. Oxygen source formulation 7 is contained in reaction chamber 2.

(65) Slide bar 22 can be actuated in an analogous manner as the breaking device 18 in FIG. 12, and the cutting device 20 in FIG. 13. Once actuated, slide bar 22 pushes receptacle 5 towards spike 23, receptacle 5 is ruptured, and ionic liquid formulation 8 is injected through injection lance 24 into reaction chamber 2. Preferably, injection lance 24 is provided with several holes (not shown) in order to provide uniform distribution of ionic liquid formulation 8. Ionic liquid formulation 8 soaks oxygen source formulation 7, and the peroxide decomposition reaction starts, generating oxygen. The oxygen leaves reaction chamber 2 via membranes 16.

(66) Analogously to the embodiments described above, the arrangement of oxygen source formulation 7 and ionic liquid formulation 8 may be different from the arrangement illustrated in FIG. 14. In particular, if not a liquid, but solid matter is contained in the injection device or dosing unit 21, no receptacle 5 is required, and means for destroying the receptacle, such as spike 23, and an injection lance are also not required.

(67) FIG. 15 depicts an embodiment of the device 1 for generating oxygen which is similar to the embodiment depicted in FIG. 12. Different from the embodiment of FIG. 12, the device for generating oxygen of FIG. 15 is contained in a container 10 surrounding and protecting reaction chamber 2. In this case, the oxygen generated is not directly released into the environment, but rather enters into a gas space 11 between gas permeable membrane 16 and an upper wall of container 10. The oxygen exits gas space 11 via a gas outlet 12 which may be, for example, provided with a filter.

(68) A device 1 as shown in FIG. 15 typically does not need any further thermal insulation. Rather, container 10 provides for sufficient insulation. If desired, a thin layer (for example, having a thickness of about 1 to 3 mm) of an insulating material may be placed between the outer wall of reaction chamber 2 and the inner wall of container 10. Such an insulating material may also serve the additional purpose of holding reaction chamber 2 tightly fixed in place within container 10. No insulating material should be provided between membrane 16 and the container wall opposite to membrane 16, i.e. in gas space 11.

(69) Housing the reaction chamber within a container is particularly advantageous in devices for generating oxygen having more than one reaction chamber, for example two reaction chambers or a plurality or multitude of reaction chambers 2. An embodiment having eight reaction chambers 2 is illustrated in FIG. 16.

(70) In the device for generating oxygen illustrated in FIG. 16, reaction chambers 2 are shown schematically. Generally, the construction of reaction chambers 2 is not limited in any manner. For example, reaction chambers as illustrated in FIGS. 12 to 14 can be used. Furthermore, the arrangement of the reaction chambers is not limited to the arrangement shown in FIG. 16. Rather, the reaction chambers may be arranged within the container 10 in any appropriate manner.

(71) Oxygen generation within reaction chambers 2 is initiated upon activation of reaction chambers 2. In the embodiment shown in FIG. 16, all reaction chambers 2 are activated simultaneously by a common activation mechanism, such as a spring, designed for pushing a plate 18 towards reaction chambers 2, as described in connection with FIG. 12. Alternatively, each reaction chamber may be activated individually, i.e. may have its own activation mechanism, or several reaction chambers may be arranged to groups, each group having its own activation mechanism. For example, in the embodiment of FIG. 16, the eight reaction chambers might be arranged into two groups of four chambers, each group having its own activation mechanism.

(72) Container 10 provides a gas space 11 receiving oxygen from all reaction chambers 2, and the oxygen collected within gas space 11 exits gas space 11 via gas outlet 12. Alternatively, gas space 11 may be divided into a plurality of compartments. A separate compartment, having its own gas outlet, may be attributed to each reaction chamber 2, or one compartment may provide a common gas space for a group of reaction chambers 2. For example, container 10 may provide two gas spaces 11, and each gas space 11 may collect oxygen from four reaction chambers 2.

(73) A device for generating oxygen having several reaction chambers 2 allows to extend oxygen generation over a long time period. As explained above, the time point of onset of the decomposition reaction can be manipulated by choosing appropriate active ionic liquids and, in particular, by minimising or maximising the accessible surface area of the hydrogen peroxide adduct compound, for example by milling the peroxide compound to a fine powder or by pressing the peroxide compound into powder compacts. The higher the compacting pressure, the higher the density of the resulting powder compacts will be, thus minimising the accessible surface area of the peroxide compound.

(74) In a device as illustrated in FIG. 16, each of the 8 reaction chambers 2 may be charged with a different composition for generating oxygen. For example, four chambers may be charged with the compositions used in example 2, which produce oxygen at four different points in time, a first flush of oxygen being available already 15 seconds after mixing of the oxygen source and the active ionic liquid, and a last flush of oxygen being available about three minutes after mixing of the oxygen source and the active ionic liquid.

(75) The remaining four reaction chambers may be charged with the same composition that provides the last flush of oxygen (three minutes after mixing), however, with oxygen source formulations which have been pressed into powder compacts, the compacting pressure increasing from chamber to chamber. In these chambers, the onset of the decomposition reaction will be further delayed, as compared to the chamber providing a flush of oxygen three minutes after mixing, the delay increasing with increasing compaction pressure. This measure further extends the time span wherein breathable oxygen is available.

(76) Examples 9 and 10 below illustrate oxygen evolution from a device for generating oxygen having nine reaction chambers (example 9), and gas evolution from a device for generating oxygen having 11 reaction chambers as well as the temperature profiles of the 11 reaction chambers (example 10).

EXAMPLE 9

(77) The ionic liquid formulations listed in table 9 were charged into the reaction chambers of a device for generating oxygen having 9 reaction chambers. Then, each chamber was charged with 10 g urea hydrogen peroxide adduct in pellet form.

(78) Oxygen evolution started a few seconds after charging the UHP pellets into the reaction chambers, in a first reaction chamber. After about half a minute, the decomposition reaction was complete in this first reaction chamber, and oxygen evolution stopped. After two minutes, oxygen evolution started in a second reaction chamber, and again the decomposition reaction was completed within about half a minute, but before oxygen evolution stopped completely, the peroxide decomposition reaction started in a third chamber. The remaining chambers followed, the delay in the onset of the decomposition reaction being characteristic for each oxygen generating composition. As a result, the volume of oxygen released increased stepwise (FIG. 17).

(79) TABLE-US-00009 TABLE 9 Formulations of the 9 single reactors. molar ratio molar ratio IL 1 IL2 IL 1 (mass) IL 2 (mass) C.sub.4mim.sub.2CuCl.sub.4 C.sub.4mimFeCl.sub.4 1 (16.8 g) 1 (13.7 g) C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 9 (29.2 g) 1 (3.4 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 3 (24.4 g) 1 (9.8 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (16.2 g) 1 (19.6 g) C.sub.2OHmimFeCl.sub.4 C.sub.6mimFeCl.sub.4 1 (3.2 g) 9 (32.8 g) C.sub.2OHmimFeCl.sub.4 C.sub.6mimFeCl.sub.4 1 (2.9 g) 10 (33.2 g) C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 1 (2.5 g) 12 (31.1 g) C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 1 (3.3 g) 9 (30.3 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (8.1 g) 3 (29.5 g)

EXAMPLE 10

(80) The ionic liquid formulations listed in table 10 below were charged into the individual reaction chambers of a device for generating oxygen having 11 reaction chambers. In addition, 1 g urea hydrogen peroxide adduct in pellet form was charged into each reaction chamber. The oxygen generated was measured with a drum gas meter, and the temperature in each reaction chamber was measured with thermocouples (K-type) provided in each reaction chamber. The results are depicted in FIGS. 18 and 19.

(81) TABLE-US-00010 TABLE 10 IL formulations of all 11 reaction chambers molar ratio molar ratio IL 1 IL2 IL 1 (mass) IL 2 (mass) C.sub.4mim.sub.2CuCl.sub.4 C.sub.4mimFeCl.sub.4 1 (1.68 g) 1 (1.37 g) C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 9 (2.92 g) 1 (0.34 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 3 (2.44 g) 1 (0.98 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (1.62 g) 1 (1.96 g) C.sub.2OHmimFeCl.sub.4 C.sub.6mimFeCl.sub.4 1 (0.32 g) 9 (3.28 g) C.sub.2OHmimFeCl.sub.4 C.sub.6mimFeCl.sub.4 1 (1.62 g) 1 (1.82 g) C.sub.2OHmimFeCl.sub.4 C.sub.4mimFeCl.sub.4 1 (0.25 g) 12 (3.11 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (0.81 g) 3 (2.95 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (0.65 g) 4 (3.14 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (0.32 g) 9 (3.54 g) C.sub.2OHmimFeCl.sub.4 C.sub.8mimFeCl.sub.4 1 (0.30 g) 10 (3.57 g)

(82) FIG. 18 shows the oxygen flow rate provided by the 11 reaction chambers, individually, and the volume of oxygen generated versus the run time. Similar to example 9 (FIG. 17) the compositions contained in each reaction chamber generated oxygen for a short time span, with the point in time of onset of the decomposition reaction being characteristic for each oxygen generating composition. The total volume of oxygen generated increased stepwise.

(83) FIG. 19 depicts the temperature profile of each of the 11 individual reaction chambers. FIG. 19 proves that in none of the reaction chambers the maximum reaction temperature exceeded 105 C.

(84) Reverting again to FIG. 18, it can be seen that breathable oxygen is available for more than 11 minutes, however, the oxygen generation is not as continuous as would be desirable. A smooth oxygen generation can be achieved by providing gas outlet 12 of a device for generating oxygen as illustrated in FIG. 5 with a small orifice or any other means for restricting oxygen flow out of gas space 11.

(85) In each individual reaction chamber, a relatively large amount of oxygen is produced within a short time period. Within this short time period, more oxygen is available than is needed. On the other hand, there are also time periods wherein no oxygen is produced, while oxygen is needed. Consequently, phases of oxygen abundancy and oxygen deficiency alternate with one another. Restricting the outflow of oxygen from gas space 11 provides a buffer which stores excess oxygen for periods of oxygen shortage, thus rendering sufficient oxygen available for a satisfactory long time period.

(86) Since the decomposition reactions are scalable to different reactor sizes, it is easily possible to charge a device for generating oxygen with an oxygen generating composition in a sufficient amount to provide for a desired oxygen flow rate. For emergency systems such desired flow rate is typically at least 41l oxygen per minute.

(87) The devices for generating oxygen may be designed as disposable devices (for one single use) filled with a composition for generating oxygen, or as reusable devices which can be recharged after use with another composition for generating oxygen. In exemplary embodiments of this invention, oxygen source formulations and ionic liquid formulations are provided in the form of components suitable for recharging a device for generating oxygen, for example in the form of replaceable/mutually interchangeable cartridges. The cartridges are filled with an oxygen source formulation or with an ionic liquid formulation.

(88) The devices for generating oxygen according to the present invention are not sensitive to interruptions of the oxygen production process, in contrast to chlorate candles which can be easily destabilised, for example by shaking. Shaking a device for generating oxygen according to the present invention enhances mixing of the oxygen source and the active ionic liquid and, therefore, promotes the oxygen generation reaction.

(89) Furthermore, the inventive devices can be construed in such a manner, that the orientation of the devices for generating oxygen in the gravity field of the earth is arbitrary. To this end, several oxygen outlets (sealed by gas permeable membranes or other structures allowing passage of oxygen, while blocking passage of non gaseous substances) must be provided in the walls of reaction chamber 2, and the openings must be arranged in such a manner that there is always an opening, which is not covered by ionic liquid, irrespective of the orientation of the device.