Rapid Hydrogen Generation from the Reaction of Aluminum Powders and Water Using Synthesized Aluminum Hydroxide Catalysts

摘要

A synthesized and nano-sized Al(OH)~(3)powder that promotes the generation of hydrogen from a Al/water reaction is demonstrated. In this study, aluminum hydroxides are synthesized using sodium aluminate NaAlO~(2), distilled water and ethanol. The mole ratio of ethanol/water and the concentration of sodium aluminate in solution affect the crystal structure, morphology and sizes of the Al(OH)~(3)powders significantly. These Al(OH)~(3)powders contain both gibbsite and bayerite phases and exhibit excellent catalytic power on the hydrogen generation of Al/water system. It is proposed that two major characteristics of Al(OH)~(3)powders dominate the catalytic power. That is, the surface area and the high-energy sites of Al(OH)~(3). When mole ratio of ethanol/water is between 0.3–0.6 and the concentration of NaAlO~(2)is higher than 0.0167?g/ml, the synthesized Al(OH)~(3)powders are in a more gibbsite-oriented and plate-like structure. Other than above conditions result in a more bayerite-oriented and particulate-like structure. The plate-like structure exhibits strong catalytic power due to the existence of high-energy sites on the edge of plates even its surface area is not so high. The particulate-like structure may also have strong catalytic power when it has a high surface area. By taking advantage of the exothermic reaction, ~?100% yield of hydrogen can be produced from 1?g Al/10?g water system within 30?s using 3?g synthesized Al(OH)~(3). A aluminum waste scrap can also react with water using these effective catalysts and generate?~?95% yield of hydrogen within 8?min.