The sorption properties of NaBH4/MH2 (M = Mg, Ti) powder systems prepared by high energy ball milling have been thoroughly investigated. Concerning the systems containing MgH2, the 2:1 and 1:2 molar compositions have been studied and both lead to a multistep desorption pathway, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the MgH2-rich system (composition 1:2) if compared with the NaBH4-rich system (composition 2:1). Even though full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. During absorption, the unsuspected formation of the perovskite-type hydride NaMgH3 is detected and it is showed that this ternary phase contributes to reduce the gravimetric capacity of the systems. Conversely, in the 2NaBH4/TiH2 system, there is no formation of the intermetallic compound TiB2. Furthermore, a decrease in the sorption kinetics is found in comparison with the systems based on MgH2.

Sorption properties of NaBH4/MH2 (M = Mg, Ti) powder systems

MILANESE, CHIARA;MARINI, AMEDEO;
2010-01-01

Abstract

The sorption properties of NaBH4/MH2 (M = Mg, Ti) powder systems prepared by high energy ball milling have been thoroughly investigated. Concerning the systems containing MgH2, the 2:1 and 1:2 molar compositions have been studied and both lead to a multistep desorption pathway, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the MgH2-rich system (composition 1:2) if compared with the NaBH4-rich system (composition 2:1). Even though full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. During absorption, the unsuspected formation of the perovskite-type hydride NaMgH3 is detected and it is showed that this ternary phase contributes to reduce the gravimetric capacity of the systems. Conversely, in the 2NaBH4/TiH2 system, there is no formation of the intermetallic compound TiB2. Furthermore, a decrease in the sorption kinetics is found in comparison with the systems based on MgH2.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/210752
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