Abstract:

Mg-Al Hydrotalcite was prepared by a high super-saturation co-precipitation hydrothermal method using Mg（OH）₂ as magnesium source.Mg（OH）₂ was synthesized by one-step hydrothermal method.The effect of hydrothermal temperature,hydrothermal time,synthesis conditions of Mg（OH）₂ and seed addition on the crystal structure,size,morphology and BET of LDHs were studied.The results showed that when the hydrothermal temperature was 190 ℃ and the hydrothermal time was 12 h,the specific surface area of the obtained hydrotalcite was the smallest,and the morphology and structure were regular.When the magnesium hydroxide synthesized at 150 ℃ for 3 h was used as the raw material.When the mass fraction of boron impurities in the raw material was 0.020%,the grain size and thickness of the hydrotalcite were promoted;the addition of the seed crystals significantly reduced the specific surface area of the hydrotalcite,and the optimum addition amount was 0.5%（mass fraction）.The product synthesized under optimum conditions exhibited a specific surface area of 10.33 m ²/g and a thermal particle of 878 nm.

Key words: Mg-Al Hydrotalcite, high super-saturation co-precipitation hydrothermal method, crystal structure