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Effects of Stoichiometry on the H 2 ‐Storage Properties of Mg(NH 2 ) 2 –LiH–LiBH 4 Tri‐Component Systems
Author(s) -
Wang Han,
Cao Hujun,
Pistidda Claudio,
Garroni Sebastiano,
Wu Guotao,
Klassen Thomas,
Dorheim Martin,
Chen Ping
Publication year - 2017
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201700287
Subject(s) - stoichiometry , component (thermodynamics) , chemistry , analytical chemistry (journal) , materials science , inorganic chemistry , thermodynamics , physics , environmental chemistry
Abstract The hydrogen desorption pathways and storage properties of 2 Mg(NH 2 ) 2 –3 LiH– x LiBH 4 samples ( x =0, 1, 2, and 4) were investigated systematically by a combination of pressure composition isotherm (PCI), differential scanning calorimetric (DSC), and volumetric release methods. Experimental results showed that the desorption peak temperatures of 2 Mg(NH 2 ) 2 –3 LiH– x LiBH 4 samples were approximately 10–15 °C lower than that of 2 Mg(NH 2 ) 2 –3 LiH. The 2 Mg(NH 2 ) 2 –3 LiH–4 LiBH 4 composite in particular began to release hydrogen at 90 °C, thereby exhibiting superior dehydrogenation performance. All of the LiBH 4 ‐doped samples could be fully dehydrogenated and re‐hydrogenated at a temperature of 143 °C. The high hydrogen pressure region (above 50 bar) of PCI curves for the LiBH 4 ‐doped samples rose as the amount of LiBH 4 increased. LiBH 4 changed the desorption pathway of the 2 Mg(NH 2 ) 2 –3 LiH sample under a hydrogen pressure of 50 bar, thereby resulting in the formation of MgNH and molten [LiNH 2 –2 LiBH 4 ]. That is different from the dehydrogenation pathway of 2 Mg(NH 2 ) 2 –3 LiH sample without LiBH 4 , which formed Li 2 Mg 2 N 3 H 3 and LiNH 2 , as reported previously. In addition, the results of DSC analyses showed that the doped samples exhibited two independent endothermic events, which might be related to two different desorption pathways.