Purification of vanadium tetrachloride by the method of rectification

Study of liquid-vapor equilibrium in dilute solutions of vanadium oxytrichloride in vanadium tetrachloride showed that the system exhibits positive deviations from Raoult's law. The separation factor is 2.7+-0.08 at 400. The separation coefficients, calculated by the statistical method, for solutions of microimpurities (the chlorides of boron, tin, germanium, carbon, titanium, silicon, and arsenic, and vanadium oxytrichloride) in vanadium tetrachloride at 400 are 81.6, 4.4, 16.1, 14.9, 1.86, 31.4, 1.48, and 2.70. Chlorine can be removed effectively fron vanadium tetrachloride by rectification. If the rectification is conducted at 400, the chlorine concentration can be lowered to 1.6.10-7 mole%. Rectification gave vanadium tetrachloride with the following impurity content, silicon, titanium, and aluminium less than or equal to 5.10-4 wt.%, copper, zinc, boron, and magnesium xx wt.%, and antimony, arsenic, and cadmium less than 5.10-6 wt.%. The contents of carbon chloride, vanadium, oxytrichloride, and chlorine can be lowered by rectification to 5.10-7, and 1.6.10-7 mole%, respectively