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Effect of additives, ball milling and isotopic exchange in porous magnesium borohydride

机译：添加剂，球磨和同位素交换在多孔镁硼氢化物中的作用

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Magnesium borohydride (Mg(BH4)(2)) is a promising material for solid state hydrogen storage. However, the predicted reversible hydrogen sorption properties at moderate temperatures have not been reached due to sluggish hydrogen sorption kinetics. Hydrogen (H) -> deuterium (D) exchange experiments can contribute to the understanding of the stability of the BH4- anion. Pure gamma-Mg(BH4)(2), ball milled Mg(BH4)(2) and composites with the additives nickel triboride (Ni3B) and diniobium pentaoxide (Nb2O5) have been investigated. In situ Raman analysis demonstrated that in pure gamma-Mg(BH4)(2) the isotopic exchange reaction during continuous heating started at similar to 80 degrees C, while the ball milled sample did not show any exchange at 3 bar D-2. However, during ex situ exchange reactions investigated by infrared (IR) and thermogravimetric (TG) analyses a comparable H -> D exchange during long exposures (23 h) to deuterium atmosphere was observed for as received, ball milled and gamma-Mg(BH4)(2) + Nb2O5, while the Ni3B additive hindered isotopic exchange. The specific surface areas (SSA) were shown to be very different for as received gamma-Mg(BH4)(2), BET area = 900 m(2) g(-1), and ball milled Mg(BH4)(2), BET area = 30 m(2) g(-1), respectively, and this explains why no gas-solid H(D) diffusion was observed for the ball milled (amorphous) Mg(BH4)(2) during the short time frames of in situ Raman measurements. The heat treated ball milled sample partially regained the porous gamma-Mg(BH4)(2) structure (BET area = 560 m(2) g(-1)). This in combination with the long reaction times allowing for the reaction to approach equilibrium explains the observed gas-solid H(D) diffusion during long exposure. We have also demonstrated that a small amount of D can be substituted in both high surface area and low surface area samples at room temperature proving that the B-H bonds in Mg(BH4)(2) can be challenged at these mild conditions.
机译：硼氢化镁（Mg（BH4）（2））是用于固态储氢的有希望的材料。然而，由于氢气吸附动力学缓慢，尚未达到中等温度的预测可逆氢气吸附性能。氢气（H） - >氘（D）交换实验可以有助于了解BH4 - 阴离子的稳定性。已经研究了纯γ-mg（BH4）（2），球磨机Mg（BH4）（2）和具有添加剂镍偶摩洛德（Ni3b）和二烯鎓氧化镍（NB2O5）的复合材料。原位拉曼分析证明，在纯γ-mg（BH4）（2）连续加热期间的同位素交换反应开始于类似于80℃，而球研磨样品未在3巴D-2处显示任何交换。然而，在通过红外（IR）和热升降（Tg）研究的EX原位交换反应期间，在长曝光（23h）期间，观察到氘气氛的相当的H - > D exchange，以接受，球研磨和γ-mg（BH4 ）（2）+ Nb2O5，而Ni3b添加剂阻碍同位素交换。显示比表面积（SSA）对于接收的γ-Mg（BH4）（2）表示非常不同，BET面积= 900m（2）g（-1）和球磨镁（BH4）（2） ，BET区域=30μm（2 )g（-1），这解释了为什么在短时间内没有观察到球磨（无定形）Mg（BH4）（2）的气固H（D）扩散原位拉曼测量的框架。热处理的球研磨样品部分恢复了多孔γ-Mg（BH4）（2）结构（BET面积=560μm（2）G（-1））。这与允许反应接近的长反应时间结合均衡解释了在长曝光期间观察到的气体固体H（d）扩散。我们还证明，在室温下，少量D可以在高表面积和低表面积样品中被取代，证明Mg（BH4）（2）中的B-H键可以在这些温和条件下攻击。

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  • 来源
    《RSC Advances》 |2018年第49期|共9页
  • 作者

    Heere Michael; Zavorotynska Olena; Deledda Stefano; Sorby Magnus H.; Book David; Steriotis Theodore; Hauback Bjorn C.;

  • 作者单位

    Inst Energy Technol Dept Neutron Mat Characterizat NO-2027 Kjeller Norway;

    Inst Energy Technol Dept Neutron Mat Characterizat NO-2027 Kjeller Norway;

    Inst Energy Technol Dept Neutron Mat Characterizat NO-2027 Kjeller Norway;

    Inst Energy Technol Dept Neutron Mat Characterizat NO-2027 Kjeller Norway;

    Univ Birmingham Sch Met &

    Mat Birmingham B15 2TT W Midlands England;

    Inst Nanosci &

    Nanotechnol NCSR Demokritos Athens 15341 Greece;

    Inst Energy Technol Dept Neutron Mat Characterizat NO-2027 Kjeller Norway;

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  • 正文语种 eng
  • 中图分类 化学;
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