Hydrogen Generation by Alcoholysis Reaction of AZ Magnesium Alloys

Abstract

This study investigated hydrogen formation by reaction of commercially available AZ magnesium alloys and methanol. AZ31 alloy with 3 mass% Al and 1 mass% Zn showed a high hydrogen generation performance. 2 g of its alloy chips completely reacted within 10 min to produce 2000 cm³ of hydrogen, which is almost a conversion yield of 100%. The heat caused by the exothermic reaction accelerated the formation of hydrogen. The reaction became slower with an increase in Al content of Mg alloy and needed 100 min to complete for AZ91 alloy with 9 mass% Al because of an increase in corrosion resistance. However, the hydrogen formation of AZ91 alloy chip was improved by mixing with AZ31 alloy chips, and completed by 20 min. The by-product of the reaction was Mg(OCH₃)₂, and then converted to MgO by heating to 500°C. A hydrolysis reaction changed Mg(OCH₃)₂ to Mg(OH)₂, which is environmentally friend and safe material. Therefore, it is said that the commercial AZ alloys are useful for hydrogen generation by reaction with methanol.