【摘要】 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。更多还原

【Abstract】 New Ni-Sn(Ⅱ)-Al layered double hydroxides(NiSnAl-LDHs) were successfully synthesized using coprecipitation by modifying the mole ratio of n(Ni)/n(Sn) and n(Ni+Sn)/n(Al).The synthesized materials with unitary hydrotalcite phase can be obtained if n(Ni)/n(Sn)≥16 or n(Ni+Sn)/n(Al)=2-5.When n(Ni)/n(Sn)≤12,the synthesized samples contain a SnO phase as well as a hydrotalcite phase.The structure of Ni20SnAl7-LDHs particles is hexagonal and the powders are well dispersed with a size of 80 nm.Sn-substituted LDHs samples showed less thermal stability compared to Ni3Al-LDHs.With the ratio of n(Ni+Sn)/n(Al) increasing,the decomposition temperature of the hydroxyl layer and interlayer carbonate decreased.The H2-TPR(temperature programmed reduction) characterization of NiSnAl-LDHs showed that the reductive process of LDHs contains two steps.The low-temperature reductive peak seems to be resulted from the direct reduction of Ni/Sn ions within the layers,while the high-temperature reductive peak seems to be resulted from the reduction of NiSn(O).Additionally,the NiSnAl-LDHs tend to be reduced as the Sn content increases or the Al content decreases.更多还原