Quantum–Chemical Simulation of Molecular Hydrogen Abstraction from Magnesium Borohydride Diammoniate
摘要
Abstract
Within the framework of the cluster approach using the 6‒31G* basis set and the hybrid density functional (B3LYP), we modeled successive abstraction of H2 from complexes (Mg(BH4)2⋅2NH3)2 and (Mg(BH4)2⋅2NH3)4. It was found that the initial stage of dehydrogenation needs overcoming energy barriers ~1.5‒1.2 eV, which requires preheating. Then the process can proceed with energy release until about 10 wt % of H2 is extracted. For a higher degree of conversion, additional energy costs exceeding the combustion heat of H2 will be required when extracting more than 12.5 wt % of H2. Therefore, further dehydrogenation of this compound may be inexpedient from the energy point of view.