The Effect of Varying Synthesis Methods on Mg-Al Hydrotalcite

Mg-Al hydrotalcites were synthesised by coprecipitation, hydrothermal and hydro-reconstruction methods.Detailed comparative analysis of structure and morphology were made by XRD,SEM and TG-DSC techniques.It had been found that the hydrothermal treatment elevated the hydrotalcite content and significantly improved the hydrotalcite crystallinity.Meanwhile a growth of hydrotalcite crystals and a remarkable decrease of surface area were observed after hydrothermal treatment.Since a strong agglomeration of primary particles occurred during preparation,the particle size of the samples synthesized by coprecipitation distributes in a wide range.Governed by a strong edge-surface platelet interaction,these aggregates gathered in a form so-called sand rose morphology.XRD patterns and scanning electron micrographs revealed that rehydration of the samples calcined at 450℃ resulted in the reconstruction of the layered structure,owing to its memory effect.