Hydrogen generation via hydrolysis of H-CaMg2 and H-CaMg1.9Ni0.1

Hydrogen generation via hydrolysis of hydrides from hydrogenated CaMg2 (abbreviated as H-CaMg2 hereafter) and hydrogenated CaMg1.9Ni0.1 (abbreviated as H-CaMg1.9Ni0.1 hereafter) alloys has been investigated in pure water without addition of any catalyst. Experimental results show that the hydrolysis of H-CaMg2 is fast when immersed in water with the hydrogen generation yield of 800 mL/g within 1 min. For CaMg1.9Ni0.1 alloy, the addition of Ni element spurs the hydrogen absorption at room temperature and significantly enhances the hydrolysis properties with fast and continuous hydrogen release yield of 1053 mL/g in 12 min, which is 94.6% of the theoretical hydrogen yield of H-CaMg1.9Ni0.1. The excellent hydrolysis properties of Ca5Mg9H28 and the catalytic effect of MgNi2 particles are further clarified. The fast and constant hydrolysis rate of H-CaMg1.9Ni0.1 can reach higher even than 365 mL/(min g) in first 2 min. The apparent activation energy of H-CaMg1.9Ni0.1 hydrolysis in deionized water is determined to be 32.9 kJ/mol. The hydrolysis mechanism of H-CaMg2 and H-CaMg1.9Ni0.1 was also discussed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.