锌铝层状复合氢氧化物的合成研究

Study on Preparation of [ZnAl-LDH]

该研究以硝酸锌、硝酸铝为原料，氢氧化钠为沉淀剂，采用恒定PH值法和变化pH值法进行共沉淀合成锌铝层状复合氢氧化物[ZnAl－LDH].全面探讨了各种因素在合成过程中的影响，以XRD分析确定其结构类型，通过TG－DTA考察其热行为．结果表明，在该研究的实验条件下，无需氮气保护，即可在较宽范围内合成结构单一、结晶度高的复合层状物．首次提出以115℃、2h的短时间水热处理代替传统的80℃、20h的回流处理，大大简化操作过程，缩短反应时间.实验结果表明，合成体系中pH值不同，合成LDH相应的Zn／Al比范围不同，而土板层间水含量又与合成物中Zn／Al比有关．在诸多的影响因素中，pH值是最关键的影响因素．

The preparation of ZnAl Layered Double Hydroxide [ZnAl-LDH]was studied.ZnAl-LDH was synthesized by the methods of variable and constant pH respectively with the materials of Zn(NO3)2, Al(NO3)3, NaOH. The effects of each factor on preparation of LDH were disscused systematically by XRD and TG-TDA data.It was showed that single LDH with high crystallinity can be prepared at the test conditions without N2 gas protection. 80℃, 2h reflux treatment can be replaced by 115℃, Zh hydrothermal treatment. Zn/Al ratio veries with different pH values. The amount of water localized in the interlayers is related to Zn/Al ratio.Among the factors,pH value is the most effective.