Oxidation of Aluminum in Sub- and Supercritical Water: Influence of Temperature and Duration on the Composition of Solid Oxidation Products

We report an experimental study of oxidation of aluminum with sub- and supercritical water in the range 350–410°C for 60 to 300 min. The results demonstrate that oxidation under such conditions yields aluminum hydroxides and oxides with a large surface area. The specific surface area of the oxidation products has been shown to vary nonmonotonically with process temperature, which is caused the formation of various compounds and aluminum oxide phases. Calcination of the oxidation products at 550°C led to the formation of γ-, χ- and α-Al2O3, in relative amounts determined by the temperature and duration of oxidation in water.