Direct electrochemical preparation of CeNi₅ and La_xCe_1−xNi₅ alloys from mixed oxides by SOM process

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• 作者：Bingjian Zhao ; Xionggang Lu ; Qingdong Zhong ; Chonghe Li ; Shuanglin Chen
• 关键词：Molten salt ; CeNi₅ ; Oxygen-ion membrane ; Oxide
• 刊名：Electrochimica Acta
• 出版年：2010
• 出版时间：1 March 2010
• 年：2010
• 卷：55
• 期：8
• 页码：2996-3001
• 全文大小：1319 K

文摘

A novel SOM process was used to prepare CeNi₅ and La_xCe_1−xNi₅ hydrogen storage alloys directly from their mixed oxides. The electrolytic reduction was carried out in molten CaCl₂ system at 1000 °C. The reduction mechanism was investigated by analyzing the chemical compositions and the phase constitutions of the intermediate products of electrolysis. The results suggested that the reduction of NiO–CeO₂ may take place in two steps: first, NiO was reduced into Ni and CeO₂ reacted with CaCl₂ to form CeOCl, then Ni reacted with CeOCl leading to the formation of CeNi₅. It was found that the reduction rate increased while decreasing the pressure load of the mixed oxide pellets. Furthermore, CeNi₅ could not be produced if the pressure load was lower than 10 MPa. It was also found that the pellets of NiO–CeO₂ could be completely reduced to CeNi₅ alloy by the SOM process, which was greatly excelled than FFC process. The successful preparation of La_xCe_1−xNi₅ (x = 0–1) alloy reported here suggests that the SOM process may be promising for the industrial application of producing such alloys.