Acceleration of the pyrolysis of magnesium chloride hexahydrate by graphene

Abstract

Anhydrous magnesium chloride is a conventional raw material for the electrolytic production of magnesium metal. Its preparation contributes about 50 % of the overall cost of the electrolytic production of magnesium metal. The search for a new process for the preparation of anhydrous magnesium chloride at a low cost has attracted much attention. In this study, the effects of graphene on the pyrolysis of MgCl₂⋅6H₂O were investigated by comparing the thermal decomposition processes of MgCl₂·6H₂O and MgCl₂·6H₂O-graphene, using TG, DTG, DSC, XRD, FTIR techniques and theoretical calculations. It was found that the addition of graphene can reduce the energy barrier for the pyrolysis of MgCl₂⋅6H₂O, accelerate the pyrolysis reactions, reduce the reaction temperature and energy consumption. The cation-π interactions between graphene and Mg²⁺, and the good thermal conductivity of graphene accelerate the thermal decomposition. The results obtained would be helpful for understanding the decomposition processes and mechanisms of MgCl₂·6H₂O under the assistance of graphene, and for exploring new techniques for MgCl₂·6H₂O dehydration.