Research of hydrogen generation by the reaction of Al-based materials with water

Al, CaO and salt powder mixtures are used as the starting materials to prepare the Al-based materials by the mechanical ball-milling method for hydrogen generation. The effects of preparation and reaction parameters on the hydrogen generation are investigated in this paper. With increasing ball milling time, the Al crystallite size is reduced and the reaction activity of Al is improved. But the overlong ball milling time easily causes the oxidation of Al and decreases its hydrogen yield. CaO can provide OH- for the hydrogen generation reaction by hydrolysis. Increasing the NaCl addition can accelerate the activation of Al and promote its hydrogen generation. In the water containing chloride ions and sulfate ions, the hydrogen generation rate is obviously improved. But Mg2+ ions will reduce the hydrogen yield due to its strong affinity to OH-. The maximum hydrogen yield is gained in the water at 30 degrees C There are some CaO on the surface of Al particle in the Al-based materials, which can improve the air oxidation resistance in air. Storing the Al-based materials in air with relative humidity of 50% at 30 degrees C for 40 h, the hydrogen yield is still kept at 89%. (C) 2012 Elsevier B.V. All rights reserved.