Synthesis and Characterization of (Co,Ni)O Solid Solutions As Protective Coatings for Inert Anodes in Aluminum Electrolysis

摘要

The industrial production of primary aluminum from alumina ore (Al_2O_3) is still carried out by the Hall-Heroult process. The process relies on dissolving alumina in an electrolyte consisting mainly of liquid Na_3AlF_6 at 950-1000°C. While the reduction of dissolved Al~(3+) ions in aluminum occurs at the cathode, the complementary reaction occurs at a carbon anode that is consumed to form carbon dioxide, which necessitates its regular replacement (every 25 days). The overall reaction is the following: Al_2O_3 + 3/2 C= 2 Al + 3/2 CO_2 Canadian aluminum smelters produce annually about 6 Mt of CO_(2 eq)(reported in 2017), which is equivalent to the CO_2 amount generated annually by about 2 million cars.