Theoretical study on the reversible storage of H2 by BeO

The potential energy surface for the BeO + H-2 --> HBeOH --> Be + H2O reaction has been studied using the G2(MP2) method. BeO is shown to be able to trap molecular hydrogen forming the HBeOH molecule, 88.9 kcal/mol below the reactants. The reaction proceeds by barrier-less formation of the OBeH2 molecular complex that isomerizes to HBeOH with a low barrier. HBeOH can be also formed in the reaction of Be atoms with water which has a barrier of 13.4 kcal/mol. The HBeOH molecule corresponds to a deep well on the potential energy surface and should be thermodynamically stable. The energy barrier for the H-2 release from HBeOH, 77.0 kcal/mol, is about 11 kcal/mol lower than that for the H2O release, making selective release of molecular hydrogen possible. (C) 2000 Elsevier Science B.V. All rights reserved.