雷尼镍作为高效氨硼烷水解制氢催化剂研究

Raney Ni as a high-performance catalyst for the hydrolysis of ammonia borane to produce hydrogen

  • 摘要: 氨硼烷(AB)作为一种环境友好、无毒、室温稳定并高含氢量(质量储氢密度达19.6%)的储氢材料受到人们的广泛关注。然而,其室温水解制氢过程是动力学缓慢过程且需要贵金属催化剂。本工作中,通过对NiAl合金在110 ℃下进行高浓度NaOH(6.25 mol/L)处理,发现自制的雷尼镍(W-r)催化剂在室温下展现出优异的AB水解催化性能(碱性条件下小试反应可以实现60 s完全水解),甚至高于20% Pt/C催化剂。其在室温下的表观活化能仅为26.6 kJ/mol,且转换频率(TOF)值高达51.42 min−1。此外,其高密度和磁性能使得催化剂很容易进行磁分离。最后,基于实验推断了雷尼镍催化AB水解可能的反应机理。作为一种工业催化剂,雷尼镍已经实现了低成本规模制备。本研究为发展低成本规模制备、可回收的AB水解催化剂提供了一条非常有前景的途径。

     

    Abstract: Ammonia borane (AB) has received much attention as an environmentally friendly, non-toxic, room temperature stable hydrogen storage material with high hydrogen content of 19.6%. However, its hydrolysis for hydrogen production at room-temperature is kinetically slow and requires precious metal catalysts. In this work, it is found that the prepared Raney Ni W-r treated with high concentration of NaOH (6.25 mol/L) at 110 °C exhibited excellent catalytic performance for AB hydrolysis at room temperature. The Raney Ni W-r can promote the AB complete hydrolysis within 60 s under basic condition at small sized trials, even higher than that of the 20% Pt/C catalyst. Its apparent activation energy at room temperature is only 26.6 kJ/mol and the turnover frequency (TOF) value is as high as 51.42 min−1. Owing to its high density and magnetic properties, the catalyst is very easy for magnetic separation. Furthermore, possible mechanism of the hydrolytic reaction of AB based on experimental results is proposed. As a well-established industrial catalyst, Raney Ni has been prepared on a large scale at low cost. This study provides a promising pathway for the large-scale preparation of low-cost and recyclable catalysts for AB hydrolysis.

     

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