Selective hydrolysis of trace TiCl4 from VOCl3 for preparation of high purity V2O5

Given the strong demands for high purity vanadium products dedicated for all-vanadium redox flow battery (VRFB), numerous preparation technologies have been developed. One of them, the chloride process that using vanadium oxytrichloride (VOCl3) as purification intermediate presents distinct technical advantages. The intermediate is readily purified via distillation process to remove most of the impurities. However, the trace titanium tetrachloride (TiCl4) is difficult to be removed, due to close saturated vapor pressures. In present work, based on thermodynamic calculation and analyses, we found that TiCl4 reacts with water significant preferentially to form the corresponding oxide, compared with VOCl3. Then we proposed a novel method to remove trace TiCl4 from VOCl3 by selective hydrolysis - distillation. The related experiments were conducted and validated the feasibility of the innovative process. Vanadium pentoxide (V2O5) with purity higher than 99.99 wt% (4N) was further prepared from the purified VOCl3 by precipitation - calcination.