Electrolysis of solid MoS2 in molten CaCl2 for Mo extraction without CO2 emission
Electrochemistry Communications 9(2007)1951-1957，-0001，（）：
Sintered (300℃) porous pellets of MoS2 were electrolysed to elemental S and Mo in molten CaCl2 (800-900℃) under argon at 1.0-3.0V for 1-20h. On a graphite anode, the product was primarily S (but traces of CS2 could not yet be excluded by this work) and evaporated from the molten salt, allowing the electrolysis to continue. It then condensed to solid at the lower temperature regions of the system. The anode remained intact after repeated uses. The MoS2 pellet was highly conducting at high temperatures and could be fast electroreduced to fine Mo powders (0.1-1.0lm) in which the S content could be below 1000ppm. No reduction occurred at voltages below 0.5V. Partial reduction was seen at 0.5-0.7V, and converted MoS2 to a mixture of MoS2 and Mo3S4, orMo3S4 and Mo with the Mo content increasing with the voltage. Cyclic voltammetry of the MoS2 powder in a Mo-cavity electrode, together with the electrolysis results, revealed the reduction mechanism to include two steps: MoS2 to Mo3S4 at 0.28V (potential vs. Ag/AgCl), and then to Mo at -0.43V.