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： The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD,IR and TG-DTA.Although both have the same crystal structures,their thermal stabilities are quite different.During the thermal decomposition process,Mg-Al-CO3 hydrotalcite exhibits two steps- desorption of interlayer water occurs at 200℃ ,followed by dehydroxylation of the brucite-like layers and loss of carbonate at 400℃ ,Zn-Al-CO3 hydrotalcite decomposes in one step-the desorption of interlayer water, structural water and carbon dioxide occurred at the same time at 200℃ . The results of a theoretical study indicate that the bond strengths of OH-CO3-OH and OH-H2O-CO3-OH in Mg-Al-CO3 hydrotalcite are stronger than those in Zn-Al-CO3 hydrotalcite.It has been shown that the thermal stability of Mg-Al-CO3 hydrotalcite is higher than that of Zn-Al-CO3 hydrotalcite.
: The structures of Mg-Al-CO3 and Zn-Al-CO3 hydrotalcites have been studied by means of XRD, IR and TG-DTA. Although both of the same crystal structures, their thermal stabilities are quite different. , Mg-Al-CO 3 hydrotalcite exhibits two steps-desorption of interlayer water occurs at 200 ° C., followed by dehydroxylation of the brucite-like layers and loss of carbonate at 400 ° C., Zn-Al-CO 3 hydrotalcite decomposes in one step-the desorption of interlayer water, structural water and carbon dioxide occurred at the same time at 200 ° C. The results of a theoretical study indicate that the bond strengths of OH-CO3-OH and OH-H2O-CO3-OH in Mg-Al-CO3 hydrotalcite are stronger than those in Zn-Al-CO3 hydrotalcite. It has been shown that the thermal stability of Mg-Al-CO3 hydrotalcite is higher than that of Zn-Al-CO3 hydrotalcite.