Co-B合金在NaBH_4现场催化制氢中的应用研究

Study on Co-B alloys for on-board hydrogen generation from sodium borohydride

采用溶液法制备了Co-B前驱物,并经过不同温度的处理得到了一系列的Co-B合金。对Co-B合金的结构表征发现,随着热处理温度的增加,Co-B前驱物经历了一个由非晶态向晶态的转变过程,同时比表面呈逐渐下降的趋势。X射线衍射结果表明,CoxB合金在400℃下生成了CoB、Co、α-Co的混合相,并在温度升高到600℃以上完全转化为立方晶系的金属Co。在500℃下处理的Co-B合金,其主相为高活性的CoB,因而具有最佳的催化活性,在催化NaBH4的水解反应时每克催化剂可得到近3.0 L/min的制氢速率。

Co-B precursor was prepared via a solution reaction method, and Co-B alloys were obtained by heating their precursor at various temperature. Structural characterizations showed that the precursor experienced a phase transition from an amorphous phase to crystal phases, and the corresponding BET surface area got a tendency to decrease with increasing heating temperature. XRD results indicated that at 400℃, Co-B alloy was at a mixed phase of CoB, Co and α-Co, and the mixed phase would be entirely converted into a cubic cobalt phase when temperature was more than 600℃. The Co-B alloy treated at 500℃ had a major phase of high active CoB, and thus has the best catalytic activity, which can achieve a hydrogen generation rate near 3.0 L/min by per gram catalyst when accelerating the hydrolytic reaction of NaBH4.