OXYGEN GENERATOR AND METHOD OF DECELERATING OR STOPPING THE OXYGEN PRODUCTION OF AN OXYGEN GENERATING COMPOSITION

Abstract

An oxygen generator uses a composition for generating oxygen and an acidic compound, with the composition for generating oxygen including an oxygen source, an ionic liquid, a metal oxide compound and optionally a basic compound. The oxygen source is a peroxide compound, the ionic liquid is in the liquid state at least in a temperature range from −10° C. to +50° C., the metal oxide compound is an oxide of a single metal or of two or more different metals which are from groups 2 to 14 of the periodic table of the elements. There is also described a method for decelerating or stopping the oxygen production from an oxygen generating composition, and a device for generating oxygen in a controlled manner.

Claims

1. An oxygen generator comprising a composition for generating oxygen, the composition including an oxygen source, an ionic liquid, and a metal oxide compound; an acidic compound for decelerating or stopping oxygen production, or if the ionic liquid is an acidic compound or contains an acidic compound; optionally, a composition for generating oxygen, the composition including an oxygen source, an ionic liquid, a metal oxide compound, and a basic compound; and a further acidic compound for decelerating or stopping an oxygen production; wherein said oxygen source comprises a peroxide compound; said ionic liquid is in the liquid state at least in a temperature range from −10° C. to +50° C.; and said metal oxide compound is an oxide of a single metal or of two or more different metals, and said single metal or two or more different metals are selected from the metals of groups 2 to 14 of the periodic table of the elements.

2. The oxygen generator according to claim 1, wherein said oxygen source is selected from the group consisting of alkali metal percarbonates, alkali metal perborates, urea hydrogen peroxide, and mixtures thereof.

3. The oxygen generator according to claim 1, wherein: said ionic liquid is at least one salt having a cation and an anion; said cation is selected from the group consisting of imidazolium, pyrrolidinium, ammonium, pyridinium, pyrazolium, piperidinium, phosphonium, and sulfonium cations; and/or said anion is selected from the group consisting of dimethylphosphate, methylsulfate, ethylsulfate, trifluoromethylsulfonate, bis(trifluoromethylsulfonyl)imide, chloride, bromide, iodide, tetrafluoroborate, hexafluorophosphate, acetate, and but-3-enoate.

4. The oxygen generator according to claim 1, wherein said metal oxide compound is selected from the group consisting of MnO.sub.2, Co.sub.3O.sub.4, CrO.sub.3, Ag.sub.2O, CuO, Fe.sub.3O.sub.4 and PbO.sub.2, or is selected from the group consisting of mixed cobalt iron oxides, mixed copper iron oxides, mixed nickel iron oxides, mixed manganese iron oxides, mixed copper manganese oxides, mixed cobalt manganese oxides, mixed nickel manganese oxides, mixed nickel cobalt oxides, mixed lanthanum iron nickel oxides, mixed lanthanum strontium manganese oxides, and mixtures thereof.

5. The oxygen generator according to claim 1, wherein a pK.sub.a-value of the acidic compound and/or of the further acidic compound is below 5, and/or wherein the oxygen generator comprises an amount of the acidic compound and/or the further acidic compound sufficient for completely reducing the metal in the metal oxide by at least one oxidation state.

6. The oxygen generator according to claim 5, wherein a pK.sub.a-value of the acidic compound and/or of the further acidic compound is below 4.5 and the oxygen generator comprises an amount of the acidic compound and/or of the further acidic compound sufficient for completely reducing the metal in the metal oxide by at least two oxidation states.

7. The oxygen generator according to claim 1, wherein the acidic compound or the further acidic compound is selected from the group consisting of inorganic acids, organic acids, acidic salts and ionic liquids having acidic functionality.

8. The oxygen generator according to claim 1, wherein the acidic compound or the further acidic compound is selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, succinic acid, citric acid, benzoic acid, sodium hydrogen sulfate, monopotassium phosphate, 1-ethyl-3-methylim idazolium hydrogen sulfate, trimethylammonium propanesulfonic acid hydrogen sulfate, 1-(4-sulfobutyI)-3-methylimidazolium hydrogen sulfate, and diethylmethylammonium methanesulfonate.

9. The oxygen generator according to claim 1, further comprising a basic compound or a further basic compound for accelerating or restarting oxygen production.

10. The oxygen generator according to claim 9, wherein the basic compound or the further basic compound is selected from the group consisting of hydroxides, basic oxides, basic salts, and ionic liquids having basic properties.

11. The oxygen generator according to claim 10, wherein the basic compound or the further basic compound is selected from the group consisting of sodium hydroxide, potassium hydroxide, potassium phosphate, sodium acetate, sodium percarbonate, potassium carbonate, calcium hydroxide, calcium oxide, 1-ethyl-3-methylimidazolium acetate, tetrabutylammonium arginine, and tetraethylammonium but-3-enoate.

12. The oxygen generator according to claim 1, wherein the acidic compound or the further acidic compound is provided in solid from or in the form of a solution or dispersion or in the form of a pure liquid substance, and/or wherein a basic compound or the further basic compound is provided in solid form or in the form of a solution or dispersion or in the form of a pure liquid substance.

13. The oxygen generator according to claim 12, wherein the acidic compound or the further acidic compound is provided in the form of a tuner compact.

14. A method of producing oxygen with an oxygen generating composition, the method comprising: providing an oxygen source, an ionic liquid, and a metal oxide compound; generating oxygen by contacting the oxygen source, the ionic liquid, and the metal oxide compound; and decelerating or stopping the oxygen production by adding an acidic compound to the oxygen source, the ionic liquid, and the metal oxide compound; or, if the ionic liquid is an acidic compound or contains an acidic compound: providing an oxygen source, the ionic liquid, a metal oxide compound, and a basic compound; generating oxygen by contacting the oxygen source, the ionic liquid, the metal oxide compound, and the basic compound; and decelerating or stopping the oxygen production by adding a further acidic compound to the oxygen source, the ionic liquid, the metal oxide compound, and the basic compound; wherein: said oxygen source comprises a peroxide compound; said ionic liquid is in a liquid state within a temperature range from −10° C. to +50° C.; and said metal oxide compound is an oxide of a single metal or of two or more different metals selected from the metals of groups 2 to 14 of the periodic table of the elements.

15. The method according to claim 14, which further comprises accelerating or restarting the oxygen production after a desired time interval by adding a basic compound or a further basic compound, once or multiple times.

16. The method according to claim 14, wherein a pK.sub.a-value of the acidic compound and/or the further acidic compound is below 5.

17. The method according to claim 16, wherein the pK.sub.a-value is less than 4.5.

18. The method according to claim 14, wherein an amount of the acidic compound and/or the further acidic compound is selected such that it is sufficient for completely reducing the metal in the metal oxide by at least one oxidation state.

19. The method according to claim 14, wherein the amount of the acidic compound and/or the further acidic compound is sufficient for completely reducing the metal in the metal oxide by at least two oxidation states.

20. A device for generating oxygen in a controlled manner, the device comprising: a reaction chamber for housing a composition for generating oxygen, the composition being a combination of an oxygen source, an ionic liquid, and a metal oxide compound; at least one dosing device housing an acidic compound and, optionally, at least one dosing device housing a basic compound, the dosing device(s) being configured to introduce the acidic compound and, optionally, the basic compound into the reaction chamber; a device for maintaining at least one of the oxygen source, the ionic liquid, and the metal oxide compound physically separate from the remaining constituents; a device for establishing physical contact of the oxygen source, the ionic liquid, and the metal oxide compound; and a device for allowing oxygen to exit the reaction chamber; wherein the metal oxide compound is an oxide of a single metal or of two or more different metals selected from the metals of groups 2 to 14 of the periodic table of the elements; the oxygen source comprises a peroxide compound; the ionic liquid is in a liquid state at least in a temperature range from −10° C. to +50° C.; and an oxygen production rate is controlled by adding the acidic compound or, optionally, the basic compound to the composition for generating oxygen.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0134] FIGS. 1-14 are graphs illustrating the decomposition of UHP (urea hydrogen peroxide), catalyzed by suspended or dissolved catalysts and termination of the decomposition reactions by addition of different amounts of acid solutions,

[0135] FIG. 15 is a graph summarizing data deducted from the results given in FIGS. 1 to 14 showing the amount of acid required for stopping reaction in dependence from strength of the acid,

[0136] FIGS. 16 to 21 are graphs illustrating decomposition of UHP catalyzed by different amounts of dissolved catalyst and termination of the decomposition reactions by adding acidic solutions,

[0137] FIGS. 22 to 27 are graphs illustrating decomposition of UHP, catalyzed by dissolved catalyst in different amounts of ionic liquid and termination of the decomposition reactions by addition of acid solutions,

[0138] FIGS. 28 to 33 are graphs illustrating decomposition of different amounts of UHP, catalyzed by dissolved catalyst and termination of the decomposition reactions by addition of acid solutions,

[0139] FIG. 34 is a graph summarizing data deducted from further experiments for determination of the amount of acid required for stopping decomposition of UHP, catalyzed by dissolved catalyst in dependence of the strength of the acid,

[0140] FIG. 35 is a sectional view of an embodiment of a device for generating oxygen according to the invention, and

[0141] FIG. 36 is a sectional view of another embodiment of a device for generating oxygen according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0142] In all graphs illustrating oxygen release, oxygen flow rate and volume are plotted against runtime, wherein runtime is the time which starts running at the time point of contacting the oxygen source, the ionic liquid and the catalyst. “Volume” is the oxygen volume released in total. Oxygen flow rate (I/h) and volume released (I) by each decomposition reaction were measured with a drum gas meter in each of the experiments.

EXAMPLE 1

[0143] In example 1 different acids or solutions of different acids were added to oxygen generating compositions during oxygen generation by decomposition of peroxide for evaluating which acids can stop the reaction and which amount of these acids is required for stopping the reaction. In general, 100 g urea hydrogen peroxide (UHP), 40 g of ionic liquid [EMIM][EtSO.sub.4] and 3 mol % MnO.sub.2 with respect to the amount of UHP were mixed to start oxygen generation. After ⅓ of the reaction time a solution of an acid in 10 g [EMIM][EtSO.sub.4] was added to the reaction mixture. The kind of acid and the amount of acid were varied in these experiments. Volume of the oxygen produced in the reactions and the oxygen generation rate were measured by means of the gas meter.

[0144] Since the oxygen generating mixture needed some time to equilibrate after addition of the acidic compound stopping of the reaction was assessed only 30 minutes after addition of the acidic compound. The reaction was considered as stopped when less than 1 g UHP (corresponds to 130 ml oxygen) were degraded within 100 minutes beginning 30 minutes after addition of the acidic compound. The ionic liquid (IL) [EMIM][EtSO.sub.4] had been selected because pK.sub.a-values of the anion and cation are such that they do not influence the oxygen generating reaction and do not interfere with the added acids.

[0145] Types and amounts of compounds are given in below tables.

TABLE-US-00001 TABLE 1 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 1 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Chloracetic acid 0 0 (2773 mg) (100 g) (40 g) (none) 2 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Chloracetic acid 0.23 1.5 (2773 mg) (100 g) (40 g) (4.52 g) 3 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Chloracetic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (6.03 g) 4 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Chloracetic acid 0.38 2.5 (2773 mg) (100 g) (40 g) (7.54 g)

[0146] Results are shown in FIGS. 1 and 2.

TABLE-US-00002 TABLE 2 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 5 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Tartaric acid 0 0 (2773 mg) (100 g) (40 g) (none) 6 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Tartaric acid 0.25 2.0 (2773 mg) (100 g) (40 g) (9.57 g)

[0147] Results are shown in FIGS. 3 and 4.

TABLE-US-00003 TABLE 3 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 7 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (40 g) (85 wt %) (none) 8 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (85 wt %) (6.76 g) 9 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.38 2.5 (2773 mg) (100 g) (40 g) (85 wt %) (8.45 g) 10 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.45 3.0 (2773 mg) (100 g) (40 g) (85 wt %) (10.14 g)

[0148] Results are shown in FIGS. 5 and 6.

TABLE-US-00004 TABLE 4 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 11 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Benzoic acid 0 0 (2773 mg) (100 g) (40 g) (none) 12 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Benzoic acid 0.27 2.0 (2773 mg) (100 g) (40 g) (7.79 g) 13 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Benzoic acid 0.38 3.0 (2773 mg) (100 g) (40 g) (11.69 g) 14 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Benzoic acid 0.41 3.5 (2773 mg) (100 g) (40 g) (13.64 g)

[0149] Results are shown in FIGS. 7 and 8.

TABLE-US-00005 TABLE 5 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 15 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Crotonic acid 0 0 (2773 mg) (100 g) (40 g) (none) 16 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Crotonic acid 0.15 1.0 (2773 mg) (100 g) (40 g) (2.75 g) 17 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Crotonic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (5.5 g) 18 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Crotonic acid 0.55 4.0 (2773 mg) (100 g) (40 g) (11 g) 19 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Crotonic acid 0.70 6.0 (2773 mg) (100 g) (40 g) (16.5 g)

[0150] Results are shown in FIGS. 9 and 10.

TABLE-US-00006 TABLE 6 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 20 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Acetic acid 0 0 (2773 mg) (100 g) (40 g) (none) 21 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Acetic acid 0.45 3.0 (2773 mg) (100 g) (40 g) (5.74 g) 22 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Acetic acid 0.75 5.0 (2773 mg) (100 g) (40 g) (9.57 g) 23 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Acetic acid 1.13 7.5 (2773 mg) (100 g) (40 g) (14.36 g)

[0151] Results are shown in FIGS. 11 and 12.

TABLE-US-00007 TABLE 7 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 24 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Valeric acid 0 0 (2773 mg) (100 g) (40 g) (none) 25 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Valeric acid 0.16 1.0 (2773 mg) (100 g) (40 g) (3.4 g) 26 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Valeric acid 0.31 2.1 (2773 mg) (100 g) (40 g) (6.8 g) 27 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Valeric acid 0.90 6.0 (2773 mg) (100 g) (40 g) (19.5 g)

[0152] Results are shown in FIGS. 13 and 14.

[0153] From results of experiments 1 to 27 a relation between the strength of the added acidic compound and the amount of acidic compound required for stopping oxygen generation by peroxide decomposition according to the above definition can be seen. The stronger the acidic compound, i.e. the lower the pK.sub.a-value, the smaller is the amount of the acidic compound to stop the reaction. For complete stopping of the reaction always two protons per molecule MnO.sub.2 are required. Acids having a pK.sub.a-value above 4.5 or above 5 are only able to decelerate oxygen production but not to stop the production. These results are summarized in FIG. 15.

[0154] FIG. 15 shows as a function of the strength of the acid how many equivalents of an acid in relation to MnO.sub.2 are required for completely stopping peroxide decomposition. “pk.sub.a” is designated as “pks” in FIG. 15. Filled squares symbolize complete stopping of the peroxide decomposition. The empty square given for tartaric acid refers to a complete stop of peroxide decomposition, wherein the amount of acid is given for the first pK.sub.a-value of the diprotic acid. Crosses indicate that the amount of the added acid did not result in a stop of the reaction. The horizontal dotted line indicates the lower limit for the amount of added acid for stopping peroxide decomposition. The dotted curve is a calculated curve fitted to the calculated values.

EXAMPLE 2

[0155] For examining the influence of catalyst concentration generally 100 g UHP in 40 g [EMIM][EtSO.sub.4] were mixed with 1.5, 3 or 6 mol % MnO.sub.2. After ⅓ of the reaction time a solution of lactic acid in 10 g [EMIM][EtSO.sub.4] was added to the reaction mixture. The amount sufficient for a complete stop of the reaction was determined by varying the amount of acid. Types and amounts of compounds of the compositions are given in below tables.

TABLE-US-00008 TABLE 8 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 28 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (1386 mg) (100 g) (40 g) (85 wt %) (none) 29 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.15 2.0 (1386 mg) (100 g) (40 g) (85 wt %) (3.38 g) 30 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.19 2.5 (1386 mg) (100 g) (40 g) (85 wt %) (4.23 g) 31 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.23 3.0 (1386 mg) (100 g) (40 g) (85 wt %) (5.07 g)

[0156] Results are shown in FIGS. 16 and 17.

TABLE-US-00009 TABLE 9 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 32 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (40 g) (85 wt %) (none) 33 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (85 wt %) (6.76 g) 34 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.38 2.5 (2773 mg) (100 g) (40 g) (85 wt %) (8.45 g) 35 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.45 3.0 (2773 mg) (100 g) (40 g) (85 wt %) (10.14 g)

[0157] Results are shown in FIGS. 18 and 19.

TABLE-US-00010 TABLE 10 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 36 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (5545 mg) (100 g) (40 g) (85 wt %) (none) 37 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.60 2.0 (5545 mg) (100 g) (40 g) (85 wt %) (13.52 g) 38 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.90 3.0 (5545 mg) (100 g) (40 g) (85 wt %) (20.28 g)

[0158] Results are shown in FIGS. 20 and 21.

[0159] Experiments 30, 31, 34, 35 and 38 resulted in a complete stop of the oxygen generating reaction.

[0160] The experiments show that the amount of acid required for stopping the reaction is in a linear relation to the amount of used catalyst. cl EXAMPLE 3

[0161] For determining whether the principles found depend on the amount of ionic liquid in the oxygen generating composition 100 g UHP in 20 g, 40 g or 80 g [EMIM][EtSO.sub.4] were mixed with 3 mol % MnO.sub.2 with respect to the amount of UHP. After ⅓ of the reaction time a solution of lactic acid in 10 g [EMIM][EtSO.sub.4] was added to the oxygen generating composition. The amount of lactic acid required for a complete stop of the reaction was determined by varying the amount of lactic acid.

[0162] The different oxygen generating compositions are given in below tables 11 to 13.

TABLE-US-00011 TABLE 11 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Exp't (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 39 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (20 g) (85 wt %) (none) 40 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.50 2.0 (2773 mg) (100 g) (20 g) (85 wt %) (6.76 g) 41 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.75 3.0 (2773 mg) (100 g) (20 g) (85 wt %) (10.14 g)

[0163] Results are shown in FIGS. 22 and 23.

TABLE-US-00012 TABLE 12 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Exp't (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 42 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (40 g) (85 wt %) (none) 43 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (85 wt %) (6.76 g) 44 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.38 2.5 (2773 mg) (100 g) (40 g) (85 wt %) (8.45 g) 45 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.45 3.0 (2773 mg) (100 g) (40 g) (85 wt %) (10.14 g)

[0164] Results are shown in FIGS. 24 and 25.

TABLE-US-00013 TABLE 13 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Exp't (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 46 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (80 g) (85 wt %) (none) 47 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.17 2.0 (2773 mg) (100 g) (80 g) (85 wt %) (6.76 g) 48 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.25 3.0 (2773 mg) (100 g) (80 g) (85 wt %) (10.14 g)

[0165] Results are shown in FIGS. 26 and 27.

[0166] Experiments 41, 44, 45 and 48 resulted in a complete stop of the oxygen production. The results show that at least in a big range the amount of acid required for stopping oxygen generation is independent from the amount of ionic liquid.

EXAMPLE 4

[0167] For examining scalability 50 g, 100 g or 200 g UHP were mixed with ionic liquid and 3 mol % MnO.sub.2. With respect to the amount of UHP the amount of ionic liquid was adapted in a linear relation to the amount of UHP. After ⅓ of the reaction time a solution of lactic acid in 10 g [EMIM][EtSO.sub.4] was added to the reaction mixture. The amount of lactic acid required for completely stopping oxygen generation was determined by varying the amount of acid added to the oxygen generating composition.

[0168] Type and amount of compounds of the compositions used in each of the experiments are given in below tables 14 to 16.

TABLE-US-00014 TABLE 14 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Experiment (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 49 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (1386 mg) (50 g) (20 g) (85 wt %) (none) 50 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.25 2.0 (1386 mg) (50 g) (20 g) (85 wt %) (3.38 g) 51 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.38 3.0 (1386 mg) (50 g) (20 g) (85 wt %) (5.07 g)

[0169] Results are shown in FIGS. 28 and 29.

TABLE-US-00015 TABLE 15 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Exp't (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 52 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (2773 mg) (100 g) (40 g) (85 wt %) (none) 53 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.30 2.0 (2773 mg) (100 g) (40 g) (85 wt %) (6.76 g) 54 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.38 2.5 (2773 mg) (100 g) (40 g) (85 wt %) (8.45 g) 55 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.45 3.0 (2773 mg) (100 g) (40 g) (85 wt %) (10.14 g)

[0170] Results are shown in FIGS. 30 and 31.

TABLE-US-00016 TABLE 16 Catalyst Peroxide IL Acid n(Acid)/ n(Acid)/ Exp't (Mass) (Mass) (Mass) (Mass) n(IL) n(MnO.sub.2) 56 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0 0 (5545 mg) (200 g) (80 g) (85 wt %) (none) 57 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.33 2.0 (5545 mg) (200 g) (80 g) (85 wt %) (13.52 g) 58 MnO.sub.2 UHP [EMIM][EtSO.sub.4] Lactic acid 0.50 3.0 (5545 mg) (200 g) (80 g) (85 wt %) (20.28 g)

[0171] Results are shown in FIGS. 32 and 33.

[0172] In experiments 51, 54, 55 and 58 oxygen production was completely stopped. Results show that the amount of acid required for a complete stop of the oxygen generating reaction is at least in a wide range independent from the scale of the reaction.

EXAMPLE 5

[0173] In example 5 influence of the strength of the acidic solution on oxygen production was determined by dissolving an acid in 25 g of ionic liquid [MMIM][PO.sub.4Me.sub.2] and further suspending 3 mol % MnO.sub.2 with respect to 40 g UHP. The resulting mixture was then given to 40 g UHP in a flask for starting the oxygen generation. At the beginning this resulted in a peroxide decomposition and oxygen generation in spite of the acid present in this composition since the suspension added to UHP contained the active catalyst MnO.sub.2. If the acid was strong enough and present in a sufficient amount the catalyst was reduced to soluble Mn(II). When the acid was acidic enough, oxidation of Mn(II) was prevented and peroxide decomposition and oxygen production were completely stopped. 3 days after start of the reaction a sodium hydroxide solution was given to the reaction mixture. In case that there was still peroxide that was not decomposed this peroxide was then decomposed and oxygen was produced. If there was peroxide 3 days after start of the reaction the reaction was considered as stopped.

[0174] Results are summarized in FIG. 34.

[0175] FIG. 34 shows the relation between strength of the acid and the amount required for stopping peroxide decomposition. “pK.sub.a” is designated as “pKs” in FIG. 34. In FIG. 34 filled circles symbolize that peroxide decomposition is completely stopped by addition of the given amount of acid. Empty circles symbolize data calculated from the experimental data and a polynomial fitting function. The horizontal dotted line symbolizes the lower limit for the amount of added acid for stopping peroxide decomposition. The dotted curve symbolizes the result of a fitting function of the calculated values.

[0176] FIG. 35 illustrates an exemplary device 1 for generating oxygen in a controlled manner, the device 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 constituents of the composition for generating oxygen can be enclosed in a receptacle in order to avoid contact with the remaining constituents of the composition contained in the reaction chamber 2. The device is particularly suitable for use with neutral and basic ionic liquids. In the embodiment shown in FIG. 35, two receptacles 5, 6 are arranged in the reaction chamber. Receptacle 5 contains an intimate mixture of the oxygen source 7 and the decomposition catalyst 9, for example in powder form or compressed into pellets, in a thoroughly dried condition. Receptacle 6 contains the ionic liquid 8. Alternatively, there may be only one receptacle for enclosing the peroxide/catalyst mixture, while the ionic liquid is “free” within reaction chamber 2, or ionic liquid 8 may be enclosed within a receptacle, while the peroxide/catalyst mixture is not enclosed in a separate receptacle. Further alternatively, the catalyst may be dissolved (soluble metal salts) or partly dissolved (partly soluble metal salts) or dispersed (insoluble metals salts or metal oxide compounds) in the ionic liquid. This alternative is particularly advantageous. It is, in principle, also possible to enclose only the catalyst within a separate receptacle, while the ionic liquid and the peroxide are not enclosed. It is only necessary to avoid contact between all three constituents during storage of the device for generating oxygen.

[0177] It is desirable to store the peroxide 7, the ionic liquid 8 and the catalyst 9 within the reaction chamber 2 in such an arrangement that all constituents will be able to get intimately mixed once oxygen generation is required. When, for example, an insoluble or only partly soluble metal salt is used as a catalyst, and this catalyst and the ionic liquid are provided in one receptacle, and the peroxide in another receptacle, the catalyst may settle within the ionic liquid during storage. In such a case proper mixing with the peroxide may be inhibited. Quick and perfect mixing of all constituents can be achieved when the peroxide and the soluble or insoluble catalyst are intimately mixed in advance in a dry condition, optionally compacted into moulds, and filled either into the reaction chamber 2 or into a separate receptacle 5 to be placed within the reaction chamber 2, and the ionic liquid is provided in a separate receptacle 6. Quick and perfect mixing can also be achieved when the catalyst is soluble in the ionic liquid, and is essentially dissolved therein. Placing the ionic liquid (or the ionic liquid and the catalyst) in a separate receptacle, although this is not absolutely necessary in a case where peroxide and catalyst (or the peroxide alone) are placed in a receptacle 5, constitutes an advantageous precautionary measure against accidental mixing of the constituents in case of receptacle 5 leakage or breakage. Care must be taken, when UHP and catalyst are mixed, because UHP is highly hygroscopic.

[0178] 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. 35, 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 airplane. Another exemplary trigger mechanism is an oxygen sensor sensing a low oxygen condition.

[0179] 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.

[0180] Destruction of receptacles 5, 6 causes mixing of peroxide, ionic liquid, and catalyst, and initiates oxygen generation. In order to allow that the oxygen exits reaction chamber 2, reaction chamber 2 has an opening. In the illustrated embodiment, the opening is sealed with a gas permeable membrane 16. The opening may be at a different position than shown in FIG. 35, or there may be more than one opening.

[0181] In exemplary embodiments, the oxygen generated in the device described herein may be passed through a filter or other purification means as known in the art. The device may be equipped with such means.

[0182] The oxygen generating reaction is an only slightly exothermic process, and proceeds at low temperature, i.e. below 150° C., or even below 120° C. or below 100° C. Therefore, reaction chamber 2 does not need to resist high temperatures, and may be made from lightweight, low melting materials such as plastics. 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.

[0183] The exemplary device illustrated in FIG. 35 is equipped with two injection devices 11, 11′, for examples syringes or other dosing devices. Openings 17, 17′ fluidly connect the interior spaces of reaction chamber 2 and of injection devices 11, 11′ respectively.

[0184] The injection device 11 comprises a receptacle 12, a slide bar 13 and a spike 14. The injection device 11′ comprises a receptacle 12′, a slide bar 13′ and a spike 14′. Spikes 14, 14′ are held in place by fixtures 15, 15′. Receptacles 12, 12′ are made from a material which can easily be ruptured, for example bags made from plastic foils. Receptacle 12 contains an acidic compound and receptacle 12′ contains a basic compound.

[0185] In the exemplary embodiment illustrated in FIG. 35, slide bars 13, 13′ can be actuated in an analogous manner as the braking device 18. Once actuated, slide bar 13 pushes receptacle 12 towards spike 14, receptacle 12 is ruptured and acid is injected through opening 17 into reaction chamber 2. Similarly, once actuated, slide bar 13′ pushes receptacle 12′ towards spike 14′, receptacle 12′ is ruptured and base is injected through opening 17′ into reaction chamber 2.

[0186] Actuation of braking device 18 starts the peroxide decomposition reaction in reaction chamber 2. Without interference, the decomposition reaction proceeds until all peroxide compound has been decomposed. The device illustrated in FIG. 35 allows a user to stop the peroxide decomposition reaction by actuating slide bar 13, and to save the peroxide not yet decomposed for later use. Whenever oxygen is needed again, the user may actuate slide bar 13′, thus starting the peroxide decomposition reaction again.

[0187] The device illustrated in FIG. 35 has only one injection device 11 containing an acidic compound, and one injection device 11′ containing a basic compound. Such a device allows to stop and to restart the peroxide composition reaction only once. Providing reaction chamber 2 with several injection devices containing an acid, and with several injection devices containing a base allows to stop and to restart the peroxide decomposition several times. For example, a device 1 for generating oxygen having three injection devices containing acidic compounds and having three injection devices containing basic compounds, allows a user to interrupt and to restart the oxygen production three times, or at least until all of the oxygen source has been decomposed.

[0188] If desired, a device as illustrated in FIG. 35 can be also used for reducing or increasing the oxygen flow rate by injecting an acidic compound or a basic compound, respectively into reaction chamber 2, for example when leveling out increasing or decreasing or fluctuating oxygen flow rates shall be achieved.

[0189] It is also possible to provide only injection devices filled with acid, or only injection devices filled with base. In such a case, oxygen generating device 1 will only allow to reduce the oxygen flow rate, or to increase the oxygen flow rate, respectively.

[0190] An alternative exemplary device for generating oxygen in a controlled manner is illustrated in FIG. 36. In FIG. 36 the same reference numerals as in FIG. 35 are used for designating components which correspond to components already illustrated in FIG. 35.

[0191] The device illustrated in FIG. 36 is suitable for use with acidic ionic liquids. In the illustrated embodiment, reaction chamber 2 contains a mixture of acidic ionic liquid 8, oxygen source 7 and decomposition catalyst 9, for example pellets comprising a peroxide/catalyst mixture dispersed within the ionic liquid. Of course, the acidic ionic liquid, the oxygen source and the catalyst may be provided in any different manner, for example in the form of a dispersion of oxygen source powder in a solution of the catalyst within the ionic liquid.

[0192] The exemplary device illustrated in FIG. 36 is equipped with two injection devices 11, 11′, which are identical to the injection devices 11, 11′ of the device illustrated in FIG. 35. Injection device 11 contains an acidic compound, and injection device 11′ contains a basic compound. Injection device 11 may be omitted. An oxygen generating device 1 having only injection device 11′ allows to start the peroxide decomposition reaction by destroying receptacle 12′ and injecting the basic compound through opening 17′ into reaction chamber 2. The peroxide decomposition reaction will then proceed until all peroxide compound has been decomposed, and the oxygen generated by the composition reaction will leave reaction chamber 2 through gas permeable membrane 16.

[0193] A device for generating oxygen in a controlled manner needs at least one further injection device, for example injection device 11 containing an acidic compound, as illustrated in FIG. 36. Injecting the acidic compound contained in injection device 11 into reaction chamber 2 allows to decelerate the peroxide decomposition reaction and to reduce an oxygen flow rate that is too high.

[0194] In alternative embodiments, the oxygen generating device illustrated in FIG. 36 may be provided with one or more additional injection devices containing basic compounds and/or with one or more additional injection devices containing acidic compounds. Such additional injection devices allow to increase or decrease the oxygen production rate, respectively, or to stop and restart the oxygen production several times.

[0195] The oxygen produced according to this invention is pure and at a low temperature and, therefore, ideal for applications in airplanes, in self-rescuers and in rebreathers. However, the use for technical applications such as in portable welding devices in mining and submarine applications, and in spaceflight, e.g. in control nozzles is also contemplated.

[0196] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.