Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 Kj·mol-1H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)2 was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H 2 pressure and 350 °C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, 11B{1H} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)2 samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)2.
Effect of Transition Metal Fluorides on the Sorption Properties and Reversible Formation of Ca(BH(4))(2) RID C-7241-2011 RID B-3019-2009 RID A-2096-2009 RID B-4391-2009 / Minella, Cb; Garroni, Sebastiano; Pistidda, C; Gosalawit Utke, R; Barkhordarian, G; Rongeat, C; Lindemann, I; Gutfleisch, O; Jensen, Tr; Cerenius, Y; Christensen, J; Baro, Md; Bormann, R; Klassen, T; Dornheim, M.. - In: JOURNAL OF PHYSICAL CHEMISTRY. C. - ISSN 1932-7447. - 115:5(2011), pp. 2497-2504. [10.1021/jp107781m]
Effect of Transition Metal Fluorides on the Sorption Properties and Reversible Formation of Ca(BH(4))(2) RID C-7241-2011 RID B-3019-2009 RID A-2096-2009 RID B-4391-2009
GARRONI, Sebastiano;
2011-01-01
Abstract
Light metal borohydrides are considered as promising materials for solid state hydrogen storage. Because of the high hydrogen content of 11.5 wt % and the rather low dehydrogenation enthalpy of 32 Kj·mol-1H 2, Ca(BH4)2 is considered to be one of the most interesting compounds in this class of materials. In the present work, the effect of selected TM-fluoride (TM = transition metal) additives on the reversible formation of Ca(BH4)2 was investigated by means of thermovolumetric, calorimetric, Fourier transform infrared spectroscopy, and ex situ, and in situ synchrotron radiation powder X-ray diffraction (SR-PXD) measurements. Furthermore, selected desorbed samples were analyzed by 11B{1H} solid state magic angle spinning nuclear magnetic resonance (MAS NMR). Under the conditions used in this study (145 bar H 2 pressure and 350 °C), TiF4 and NbF5 were the only additives causing partial reversibility. In these two cases, 11B{1H} MAS NMR analyses detected CaB6 and likely CaB12H12 in the dehydrogenation products. Elemental boron was found in the decomposition products of Ca(BH4)2 samples with VF4, TiF3, and VF3. The results indicate an important role of CaB6 for the reversible formation of Ca(BH4)2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
