镁铝水滑石结构记忆性及其应用研究

用共沉淀法合成了镁铝水滑石，对其结构记忆性进行了研究，并将这一特性应用于乙醇-水体系中水的脱除。结果表明，水滑石在400-700℃焙烧形成的复合氧化物LDO能在水中重新恢复原来的层状结构，当焙烧温度升高到800℃时，镁铝水滑石结构记忆性消失。经过2次重复焙烧一水合后，LDO重构时结合水的能力几乎不再发生变化。将镁铝水滑石的结构记忆性应用于乙醇溶液脱水，发现在w（H2O）=12％的乙醇溶液中，焙烧后的LDO能重新恢复层状结构，此时LDO对乙醇溶液的脱水效率为36．1％，比5A分子筛高4．3％。在w（H2O）=7％的乙醇溶液中，LDO没有发生重新水合，此时LDO对乙醇溶液的脱水效果与5A分子筛相当，脱水效率为23．5％。

Memory Effect and Its Application of Mg-Al Hydrotalcite

The ’memory effect’ of Mg-Al hydrotalcite was studied and used to dehydrate hydrous ethanol.The results indicate that after calcination the mixed oxides derived from the hydrotalcite restore the lamellar structure in water when the calcination temperature ranges from 400 to 700 ℃.When the calcination temperature was raised up to 800 ℃,the reconstruction ability of LDO disappeared.After two cycles of calcination and rehydration,the LDO exhibits steady hydration ability.The results of dehydration of ethanol/water mixtures suggest LDO can recover the layered structure in the ethanol solution of w(H2O)=12 %.The dehydration efficiency achieves 36.1 %,which was 4.3 % higher than the results of hydrous ethanol treated with 5A molecular sieve.However,in the ethanol/water mixtures of w(H2O)=7 %,hydrotalcite are difficult to recover and the dehydration efficiency was 23.5 %,which is almost the same as 5A molecular sieve.