TiO₂溶融塩電解還元時のガス発生反応

抄録

Titanium dioxides were reduced to metallic titanium via molten salt electrolysis using CaCl₂. It was reported that the efficiency was low because some side reactions produced carbon precipitates. To produce titanium more efficiently, these electrochemical side reactions were examined by cyclic voltammetry (CV). O^2- reacted with the carbon anode to form CO and CO₂ gas bubbles, which easily dissolved into the molten salt and formed CO₃^2-, subsequently generating carbon powder. CV was performed after interrupting electrolysis temporarily. The electrochemical reduction of CO₃^2- in the cathodic scan was not observed, suggesting that CO₃^2- was spontaneously reduced by Ca during electrolysis. Anodic reactions preceding Cl₂ gas generation occurred in three steps: CO and CO₂ gas generation related to O^2-, and successive CO₂ generation related to CO₃^2-.

Cyclic voltammogram and schematic image of various steps of anodic reaction.