Reversible Hydrogenation Studies of NaBH4 Milled with Ni-Containing Additives

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• 作者：Terry D. Humphries ; Georgios N. Kalantzopoulos ; Isabel Llamas-Jansa ; J酶rn Eirik Olsen ; Bj酶rn C. Hauback
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：March 28, 2013
• 年：2013
• 卷：117
• 期：12
• 页码：6060-6065
• 全文大小：230K
• 年卷期：v.117,no.12(March 28, 2013)
• ISSN：1932-7455

文摘

NaBH₄ has long been identified as a viable hydrogen-storage material due to a theoretical gravimetric H₂ capacity of 10.6 wt %. Because of the high enthalpy of decomposition of 108 卤 3 kJ mol^鈥?, thermal decomposition of the pristine material does not occur until at least 500 掳C, and thus NaBH₄ has yet to be utilized in hydrogen-storage processes. In this study, NaBH₄ has been milled with a variety of Ni-containing additives to investigate the effects on the temperatures required for thermal desorption of H₂ by temperature-programmed desorption (TPD) measurements and the products characterized by powder X-ray diffraction (PXD). Ni-containing additives have been determined to significantly enhance the thermal desorption of H₂ by at least 60 掳C (Ni (65 wt %) on Si/Al₂O₃). PCT cycling experiments have been conducted to ascertain their effects on the reversible hydrogenation of the milled NaBH₄. PXD analysis indicates that Ni reacts with B evolved during thermal decomposition to form Ni_xB_y species including Ni₃B, Ni₂B, and Ni₃B₄. A catalyst screening study of NaBH₄ with a variety of nanoparticles, chlorides, borides, and mesoporous materials has also been conducted, the most effective of which has been found to be Pd nanoparticles, which have a desorption temperature of 420 掳C, a decrease of at least 85 掳C.