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

摘要

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 La_2Mg17. 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.