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通过改变Ni/Sn和(Ni+Sn)/Al的摩尔比,采用共沉淀法成功合成了新型NiSnAl水滑石(layered double hydroxides,LDHs)。当n(Ni)/n(Sn)≥16和n[(Ni+Sn)]/n(Al)=2～5时可制备纯水滑石相材料。当n(Ni)/n(Sn)≤12时,合成样品中除存在水滑石相外,还伴随有SnO杂相。合成的Ni20SnAl7-LDHs样品形貌呈六边形,其尺寸约为80nm,并且分散性良好。热重-差热分析显示:在Ni3Al-LDHs基础上添加Sn,其热稳定性变差;随着n[(Ni+Sn)]/n(Al)增大,水滑石层板羟基及层间碳酸根的热分解温度降低。H2程序升温还原分析表明:样品还原过程包含2个阶段,低温还原峰对应于Ni/Sn从水滑石层板中直接还原,高温还原峰则为Ni/Sn从氧化物NiSnAl(O)中还原。并且Sn含量越高,Al含量越低,NiSnAl-LDHs样品越容易被还原。
By changing the molar ratio of Ni / Sn and (Ni + Sn) / Al, novel layered double hydroxides (LDHs) were successfully synthesized by coprecipitation. Pure hydrotalcite phase materials can be prepared when n (Ni) / n (Sn) ≥16 and n [(Ni + Sn)] / n (Al) = 2-5. When n (Ni) / n (Sn) ≤12, the synthesized samples were accompanied by SnO heterogeneous phase in addition to hydrotalcite phase. The morphology of the synthesized Ni20SnAl7-LDHs sample is hexagonal with a size of about 80 nm and good dispersibility. The thermogravimetry-differential thermal analysis shows that the addition of Sn on the basis of Ni3Al-LDHs deteriorates the thermal stability of the hydrotalcite as the n [(Ni + Sn)] / n (Al) The thermal decomposition temperature of carbonate decreases. The results of temperature programmed reduction showed that the sample reduction process consisted of two stages. The low temperature reduction peak corresponded to the direct reduction of Ni / Sn from the hydrotalcite lamina and the high temperature reduction peak was the reduction of Ni / Sn from the NiSnAl (O) oxide. And the higher the Sn content, the lower the Al content, the easier the NiSnAl-LDHs sample is reduced.