Thermal behavior of Mg-Al-CO3 layered double hydroxide characterized by emanation thermal analysis

Emanation thermal analysis (ETA) was used to characterize microstructure changes during heating of Mg-Al-CO3 layered double hydroxide (LDH) in the temperature range of 293-1473 K. It was confirmed by ETA that the formation of an intermediate phase with grafted CO32- anions in the hydroxide layers took place in the temperature range of 508-523 K and the formation of Mg-Al mixed oxide (MO) occurred in the range 623-773 K. The small peak of the emanation rate at 603 K indicated the degradation of the layered structure and the broad peak in the range of 1073-1273 K characterized the onset of the separation of the decomposition products of MO into MgO and Mg2Al4O7. The ETA results revealed that dehydration of the product with grafted CO32- anions occurred at lower temperatures than that of the initial Mg-Al-CO3 LDH.