Investigation of thermal decomposition of MgCl2 hexammoniate and MgCl2 biglycollate biammoniate by DTA–TG, XRD and chemical analysis

The decomposition of MgCl2·6NH3 and MgCl2·2C2H6O2·2NH3 in static air was investigated by DTA–TG, XRD and chemical analysis from room temperature to 700 °C. The results indicated that MgCl2·6NH3 took three steps to decompose to anhydrous MgCl2 below 450 °C and at higher temperatures resulted in the oxidation of anhydrous MgCl2. This theoretically confirms the validity of the operation in which Ar or N2 is used in manufacturing anhydrous MgCl2 at 650 °C. MgCl2·2C2H6O2·2NH3 experienced a complicated process of decomposition, Mg(OH)Cl and carbon were obtained at 300 °C and MgO at 530 °C, respectively, which may decrease the quality of anhydrous MgCl2.