Effects of copper on purifying crude TiCl4 with organic reagent: Morphology, property and mechanism

•The damage caused by viscous residue is successfully solved.•The complete mechanism on coking process is explored.•The mechanism on purifying crude TiCl4 is proved from various angles.•The chemical reaction equation to purify crude TiCl4 is determined. The sticky residue left from purifying crude titanium tetrachloride (TiCl4) using organic reagent has been harmful to production equipment. In this paper, it was successfully solved via using co-purifying reagent, which was prepared by doping copper powder in organic reagent. The impurity content and whiteness of TiCl4 were the indexes which were used to determine the formula of co-purifying reagent compound, the amount of residue and the optimal purifying reaction conditions. Applying the purifying reagent (co-purifying reagent), the mechanism on synergistic purifying was explored via characterizing the residue, combined with theoretical calculation. The results suggested that the copper powder played a catalytic role in improving the coking rate and degree for organic reagent, and its ID/IG ratio increased from 0.99 to 1.01, which indicated that higher proportion of amorphous carbon and more defects were obtained. Finally, VOCl3 was transformed into VOCl2 and VCl3 insoluble particles, contributing by the synergistic reduction of copper powder and amorphous carbon, and then they were removed via adsorbing on amorphous carbon.