High purity vanadium pentoxide preparation via gas phase oxidation of vanadium oxytrichloride in fluidized bed reactor

With the increasing demand for high purity vanadium pentoxide for manufacturing of all-vanadium redox flow batteries (VRFBs), production of high purity vanadium pentoxide by chlorination process is an efficient and clean approach. However, oxidation of vanadium oxytrichloride is the controlling step. In the present work, gaseous vanadium oxytrichloride oxidation and vanadium pentoxide deposition behavior on particle substrates in a fluidized bed reactor were investigated. Results showed that the thermodynamic equilibrium conversion of oxidation gradually decreased with increasing temperature above 400 °C, while the kinetic limitation was predominant at low temperatures. Subsequently, oxidation experiments were conducted to investigate the influences of parameters on the conversion efficiency. Under optimized reaction conditions, the conversion of vanadium oxytrichloride and the deposition rate of vanadium pentoxide could achieve 68.52 % and 0.48 g/(h·g), respectively. It was more preferable than previous works that the purity of deposited vanadium pentoxide products reached 99.99 wt%, while impurities that would greatly affect electrochemical performance of the VRFBs were undetectable. This novel method provides an efficient route for the preparation of high purity vanadium pentoxide along with the recycling of chlorine gas for the chlorination process, which would be a promising method for green and sustainable development of the vanadium industry.