The Absorption of Oxygen by Sodium Peroxide: Preparation and Magnetic Properties of Sodium Superoxide

Abstract

According to the literature4•6 the highest oxide of sodium that can be obtained by combustion of the metal in an excess of oxygen is the peroxide, Na2C>2. The superoxides of potassium, rubidium and cesium may be prepared by the same method.6•6 Although previous investigators7 have studied the reaction between alkaline earth metal lower oxides with oxygen at elevated temperatures and pressures in attempts to prepare higher oxides, no similar experiments have been performed with sodium peroxide. Holt and Sims5 passed oxygen at atmospheric pressure over sodium peroxide at 300-350°for sixteen hours but obtained no evidence of oxygen absorption. In a previous report8 from this Laboratory, dealing with the rapid oxidation of sodium in liquid ammonia, evidence for the existence of sodium superoxide was described.9 In the present investigation sodium peroxide has been subjected to treatment with oxygen at high pressures and temperatures in order to explore the possibility of preparing higher oxides by this method. Such treatment results in the formation of high yields of sodium superoxide. The preparation and magnetic properties of this substance are discussed in this paper.

On the Thermodynamics, the Role of the Carbon Cathode, and the Cycle Life of the Sodium Superoxide (NaO2) Battery

“…The red arrows and factors indicate the corresponding increases in oxygen activity. This is well in line with reported experimental conditions for the preparation of phase pure sodium superoxide in which sodium peroxide reacts with oxygen at partial pressures and temperatures of approximately 280 × 10 5 Pa and 475 °C . Taking the calculated value −12.2 kJ mol(Na 2 O 2 ) −1 (see Equation for the standard free enthalpy of reaction from the superoxide to the peroxide, we estimate an oxygen pressure of 133 × 10 5 Pa as minimum value to shift the equilibrium to NaO 2 , which is in reasonable agreement with the experiment in view of the uncertainty in the thermodynamic data of NaO 2 .…”

“…Considering that the thermodynamic data of less common compounds such as NaO 2 are always subject to some inaccuracy, it is also possible that sodium superoxide is the stable phase at standard conditions . However, there is some evidence that the superoxide is indeed the less stable phase, as NaO 2 can only be prepared from Na 2 O 2 by using extreme chemical conditions …”

Recent results in solid state chemistry of ionic ozonides, hyperoxides, and peroxides

“…Themost suitable method for synthesis ofNa02 is oxidation of Na2U2 with oxy gen at elevated temperatures and pressures. Kleinberg et al obtained a product containing appro ximately 96% Na02 by oxidizing sodium peroxide at 475°C and an oxygen partial pressure of 280bar [83,84]. Information concerning the solubility of sodium hyperoxidein liquid ammonia is contradictory.…”

In situ Generation of Superoxide Anion Radical in Aqueous Medium under Ambient Conditions

“…Sodium superoxide (NaO 2 ) was first prepared through a different route by Kleinberg and co‐workers in 1949 11. They obtained the maximum yield of the product by subjecting sodium peroxide to a temperature of 490 °C under an oxygen pressure of 298 atm for a period of 100 hr 11…”