Hydrogen storage properties of the Mg(NH3)6Cl 2-LiH combined system

Abstract

Metal ammine complexes (MACs) were recently regarded as one of promising materials for reversible hydrogen storage due to their high hydrogen content. In this work, a first attempt is conducted to elucidate the hydrogen storage reversibility by combining Mg(NH3)6Cl2 with LiH. It is found that hydrogen is gradually evolved from the combined system during ball milling. After 24 h of milling, approximate 3.5 mass% of hydrogen, equivalent to 6 mol Of H2 molecules, is released from the Mg(NH3)6Cl2-18LiH mixture. Additional 3.4mass% of hydrogen is further desorbed from the combined system milled for 24 h with a two-step reaction in heating process. Totally ∼12 mol of H2 molecules are librated from the Mg(NH3)6Cl2-18LiH mixture along with the formation and consumption of Mg(NH2)2 and LiNH2 in the ball milling and subsequent heating process. The resultant products consist of Li2Mg(NH)2, Li 2NH, LiH and LiCl after dehydrogenation at 310°C. Further hydrogenation experiment indicates that ∼6 mol Of H2 molecules are reversibly stored in the Mg(NH3)6Cl2- 12LiH mixture. © 2011 The Japan Institute of Metals.