Separation and Rectification of Chloroacetyl Chloride from TiCl4

Abstract

Titanium tetrachloride (TiCl₄) is an important intermediate material for the preparation of titanium products. The organic impurities in TiCl₄ are easily accumulated during the production of titanium sponges due to the problems of imperfect detection methods and the lack of effective control methods, resulting in a poor quality of sponge titanium. Among all impurities, chloroacetyl chloride (CAC) is the most important in TiCl₄. Herein, the determination of the CAC content in TiCl₄ solution, with a low detection limit of 0.633 ppm, was established by the standard addition method using Fourier transform infrared (FTIR) spectrometry. This test method presented good repeatability, excellent accuracy, and moderate precision. Furthermore, the influencing factors of CAC separation in the continuous rectification process, including the heating power (the ratio of total heating power to feed rate), reflux temperature, top tower pressure, and feed temperature were optimized based on an orthogonal experimental design. The experimental data demonstrated that the average CAC removal rate reached 78.94% ± 1.00% under the optimal distillation conditions, with 72.21% of the CAC removed via the off-gas system. Therefore, excellent control of the negative pressure of the tail gas is highly desirable for the removal of CAC impurities.