Mechanism of Hydrogen Generation via Water Reaction with Aluminum Alloys

Solid alloys of aluminum, gallium, indium and tin have been shown to react with water at room temperature to produce hydrogen and aluminum hydroxide in an exothermic reaction. The gallium, indium and tin components are inert and recoverable. The aluminum hydroxide can be recycled back to aluminum by the Hall-Heroult process. Several different experiments have been conducted to understand the reaction mechanism. There is strong evidence indicating that the presence of a liquid phase in the alloy microstructure allows for a continuous reaction between aluminum and water to generate hydrogen. Hydrogen yield and reaction rate kinetics were studied for various compositions and reaction temperatures. Alloy reactivity displayed a strong dependence on microstructure, resulting from variations in composition and method of preparation.