Production of hydrogen via hydrolysis of hydrides in Mg–La system

Abstract

Hydrogen generation via hydrolysis of 250 mg hydrogenated Mg 3La and La 2Mg 17 in 100 ml water has been investigated at 298 K. Hydrolysis reactions of hydrogenated Mg 3La and La 2Mg 17 obtained by induction melting and then hydrogenated at 298 K is found to be fast when they are immersed in water. The hydrolysis reaction of hydrogenated Mg 3La almost completes within 21 min with faster kinetics and higher yield than those obtained of hydrogenated La 2Mg 17. The hydrogen production rate is 43.8 ml min −1 g −1 of hydrogen in the first 20 min of reaction compared to a conversion yield of 88% for hydrogenated Mg 3La and 40.1 ml min −1 g −1 of hydrogen in the first 20 min of reaction for hydrogenated La2Mg17. It is related to the catalytic effect of LaH 3 formed during the hydriding process, accentuating corrosion of MgH 2 greatly. The experimental curves of hydrogen generation kinetics at room temperature are well fitted by the Avrami–Erofeev equation. The reaction mechanism of hydrogenated Mg 3La and La 2Mg 17 was also discussed.