Fabrication of pure V2O3 powders by reducing V2O5 powders with CO-CO2 mixed gases

Abstract

Vanadium (III) oxide (V2O3) can be widely used in the fields of metal ceramics, catalysts, temperature sensors, and cathode materials. In this paper, V2O3 powders are prepared via a gas-based reduction by the mixed gases of CO and CO2 in the temperature range of 783–963 K. The effects of the CO percentage and reaction temperature on the phase transition and morphology evolution of the final products are investigated. The results reveal that the reduction mechanism are different at low and high temperatures. At a temperature lower than the melting point of V2O5 (943 K), the phase transformation sequence can be described as follows: V2O5→V6O13→VO2→V2O3. The reduction process is dominated by a pseudomorphic transformation mechanism, under which the morphology of the produced V2O3 particles roughly keeps the original morphology of V2O5 particles. As the temperature is higher than the melting point of V2O5, the reduction process becomes a gas-liquid reaction, and the reaction rate obviously decreases. Compared with the V2O3 prepared at low temperatures, the morphology becomes much more irregular and compact. It is also found from the experiments that the introduction of CO2 can restrain the carbon deposition reaction and assist in increasing the purity of the V2O3 powders.