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@032 E ~Onz°\L 23128 Aug. 11, 1953 w. H. SCHECHT'ER __ 2,648,596 SODIUM SUPEROXIDE PRODUCTION Filed Aug. 5, 1950 L/ 8n0 .23a / /I.F l? I? / // ~onz°\L@0322223128E I / /or V INVENTOR. M,“mm A’. Jamel/7:62. 62%,BY @644», 744;,_ M Jul: 4 7- TORA/A 7151 Patented Aug. 114, 2,648,55 UNITED STATES ATENT OFFICE 2,648,596 SODIUM SUPEROXIDE PRODUCTION William H. Schechter, Zelienople, Pa. Application August 5, 1950, Serial No. 177,977 10 Claims. (0]. 23-.9-184). 1 2 This invention relates 'to sodium superoxide, streamof air '"or oxygen. Although in that way NaOz. it is possible to prepare potassium superoxide, or The alkali metal oxides are useful for various tetroxide, the literature on the subject shows that, purposes. For example, sodium peroxide (NazOz) curiously enough, the corresponding oxide of so and potassium superoxide, or tetroxide (K204), dium, i. e., NaOgz, has never been prepared by release oxygen in contact with moisture. They combustion or ‘metallic sodium in air or oxygen, have ‘therefore been used extensively in breathing Or by air or oxygen oxidation of sodium perox apparatus and for maintaining the atmosphere ide (NazOz), which is the highest oxide of so in closed spaces respirable, as in submarines or dium that has beenprepared heretofore by com in other places where the atmosphere vwould bustion of sodium in an oxygen-containing at otherwise become de?cient in oxygen. Those ox~ mosphere. Consequently, this desirable sodium ides are particularly adapted to such purposes be superoxide has not been available as a substitute cause when they are brought into contact with for the foregoing oxygen-evolving compositions. exhaled air the moisture contained in it reacts A primary object of this ‘invention is to pro with the oxide to liberate an amount of oxygen vide sodium superoxide. equivalent to that consumed in respiration, and Another object is to provide a method of pro at the same time the ‘oxide also ?xes the exhaled ducing sodium superoxide in admixture with low carbon dioxide. For this reason thesesubstances er oxide of sodium that issimple, easily per are especially adapted for use in breathing ap formed, and adapted to provide products contain paratus of the self-contained type. ing desired content of available oxygen. Sodium peroxide has been used on a very large 'Yet another :object is to provide a simple and scale for such purposes. However, there is theo e?ective method of making substantially pure retically available from it at N. T. P. only about NaOz. 145 cc. of oxygen per gram. Mixed oxides of so I have discovered, and it is upon this that my dium (NazOz) and potassium (K204) have there invention is in large part predicated, that if in fore been used to some extent because the form steadof followinglprior practices of producing supplied commercially gave a greater yield of the alkali metaloxidesby combustion in an oxy oxygen per unit weight than is available from gen-containing atmosphere at normal ‘pressure, NazOz, namely, about 190 to 200 cc. per gram. or at pressures r-near atmospheric, metallic so More recently, substantially “pure potassium , dium or sodiumperoxide be heated in a ‘bomb, tetroxide has been used for these purposes because ' 1. e., a closed pressure container, to an elevated there is theoretically available from it 236 cc. of temperature in (contact with oxygen under pres oxygen per gram. ' sure substantially above‘atmospheric, the super Obviously, it "is advantageous and desirable ‘to oxide is‘formed. If, however, thetemperature be obtain from such materials as great a yield/as raised while subjecting the sodium peroxide to possible of oxygen per unit weight. Thus, vwhere high oxygen pressure, the peroxide is progres space is important, the greater the yield per unit sively converted to- the superoxide by continued weight the more compact the device ‘using it. exposure at a given temperature and pressure, Also, on the same basis a given amount of the or by increase in oxygen pressure at given tem oxygen-exchanging material will have longer ef perature and time of exposure. Under proper fective life. Again, in a self-contained breathing 40 conditions substantially pure sodium superoxide apparatus the weight and compactness ‘factors can be ‘produced in this way. Or, if the pure are of importance, to minimize ‘fatigue of va Work superoxide is ‘not needed, mixtures of‘ Na2O2~NaO2 er using it, and accordingly the ‘higher the ‘oxy having greater contents of available oxygen than gen-evolving power of such a. substance the less 45 Naz'oz, ‘K02 or mixtures of them maybe pro the weight required in a canister designed to give duced by the method of the invention. a predetermined working-time. The content of sodium superoxide ‘in products Theoretically, sodiumsuperoxid'e, NaOz, would made by my-method'may be determined readily be better than sodium peroxide, potassium by treating a weighed-sample with a solution that tetroxide, or their mixtures as used heretofore, - is 2M with-respect to "HCl and 1M in ferric chlo because at 100 per cent purity it should liberate ride. From the corrected volume of O2 evolved 305.6 cc. ‘of oxygen per gram at vN. T. P. How per gram of product the weight per cent of NaOz ever, .oxides of sodium and potassiumdare pro is then calculated'by the formula duced by oxidation of therespective metals, com monly by burning the metal in contact with a 65 2,648,596 4 The numerator represents the cc. of 02 per gram peroxide is ?nely divided and presents larger beyond that required for pure NazOz, and the de surface area. The best conversions have been nominator the difference in cc. of O2 evolved per obtained with sodium peroxide made by atom gram between pure NaOz and NazOz. ization of molten metallic sodium in accordance The factors described above have been demon with U. S. Patent No. 2,405,580 to C. E. Jackson. strated by numerous tests and they are illustrated This peroxide is of very low bulk density and by the following data of runs made in a high possesses very high exposed surface area; it was pressure bomb of about 180 ml. capacity: used in the runs represented in the drawing. The graphs show how conversion of Naif): Product 10 to NaOz can be controlled in 4 to 6 hour runs according to variation in temperature and pres 1d/[tarting1ateria Press,p. s. i. Tgrapq. Tl‘iime,rs. sure. Thus, 90 per cent conversion is to be had cc. Oz/g'm. Pggzgzlt at 1450 p. s. i. 02 pressure at 350° C., or by heating at 400° C. under about 1310 p. s. i. 02 NazOz _________ .. 1, 500 450 12 277 82. 5 15 pressure. Likewise, substantially pure NaOz Nero: _________ __ 2,000 450 12 281 84. 5 NazOz _________ __ 2,000 500 2 263 73.5 (more than 99% purity) is produced at 1800 N m0: _________ _ _ 2, 000 500 4. 75 289 89. 5 p. s. i. and 400° C. Where lower contents of NaOz in Na2O2 su?ice for particular purposes I have found also that the reaction can be ac they may be had at lower pressures and tem celerated by mixing the Na2o2 with a wide va peratures, as appears from the graphs. riety of metallic oxides that act to catalyze the As further showing'how the pressure may be reaction. Thus at 2000 p. s. i. oxygen pressure. lowered through increase in pressure, at 450° C. 500° C., and two hours exposure in the small an oxygen pressure of 1700 p. s. i_. suf?ced to bomb conversions of Na2O2 to 70 per cent NaOz produce 97 per cent NaOz in 4 to 6 hours. ' were obtained with M003, V205, ‘CdO, F9203, 25 Tests have shown high purity sodium Super CrzOs, NizOs, MgO, CO203, C110, TiOz. Of oxide made in this way to ‘be satisfactorily stable these, CdO and TiOz have given optimum re at 65° C. (150° F.) so that its stability at the sults. Thus, with 1.2 per cent by weight of CdO maximum temperaturesto which it Would nor 88 per cent of NaOz was produced from NazOz mally be exposed, even in the tropics, is assured. at 2000 p. s. i. 02 and 500° C. after four hours. It tends to lose oxygen very slowly at 100° C., About 0.6 per cent of CdO has been found to however. - exert the optimum effect. The effect of T102 NaOz, or mixtures with NazOz, made at 450° (0.68 per cent by weight of the Nazoz) is shown C. is generally fused solid. It may be granu by the following data: lated or ground to prepare it for use. Operation at 400° C. causes some shrinkage of the original Product charge after 5 hours, and substantial shrinkage Press. Temp. Time after 24 hours. At 350° C. and lower there is 110 Catalyst p. s. i.’ ° 0. ’ Hrs.’ P _ t appreciable shrinkage during the conversion. cc. 021cm. Gwen '° NaCz Thus the bulk density of the product can be 40 controlled by the temperature and the duration None __________ __ 2, 000 500 4 266 75. 5 of the run. It is affected also by the pressure. TiOz __________ __ 2, 000 500 4 289 89. 5 Lower temperatures than those given above by way of exempli?cation may be used but re Runs made in a larger bomb, or autoclave, quire longer times and higher pressures, and the have shown that higher percentages of sodium 45 conversion is generally less.
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