Preparation and hydrolysis of aluminum based composites for hydrogen production in pure water

Abstract

A series of Al based composites were prepared using mechanical milling method in this paper. Effects of additives including CaO, NaCl salt and low melting point metals (Ga, In, and Sn) on the hydrolysis activity of Al based composites were evaluated in pure water. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the microstructure analysis of as-prepared samples and their hydrolysis products. The results showed that the addition of CaO, NaCl salt and low melting point metals can effectively improve the hydrolysis properties of Al based composites. Especially, Al alloys-CaO-NaCl composites exhibited a higher hydrogen yields than Al-CaO and Al-CaO-NaCl materials. The SEM images displayed that NaCl salt particles were homogeneously distributed on the surface of Al based composites and inserted into Al matrix, which may damage the surface oxide layer of Al. Furthermore, the size of NaCl salt particles was much smaller in Al alloys-CaO-NaCl composites than that in Al-CaO-NaCl composites. The XRD patterns identified that the hydrolysis products were mainly composed of AlO(OH) and Al(OH)3. The microstructure-related hydrolysis reaction mechanism of Al based composites was proposed finally. © 2014 The Japan Institute of Metals and Materials.