Gas generation reactions during TiO2 reduction using molten salt

Abstract

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）. O2- reacted with the carbon anode to form CO and CO2 gas bubbles, which easily dissolved into the molten salt and formed CO32-, subsequently generating carbon powder. CV was performed after interrupting electrolysis temporarily. The electrochemical reduction of CO32- in the cathodic scan was not observed, suggesting that CO32- was spontaneously reduced by Ca during electrolysis. Anodic reactions preceding Cl2 gas generation occurred in three steps: CO and CO2 gas generation related to O2-, and successive CO2 generation related to CO32-