Duan Rui, Peng Wencai, Zhang Jianshu, Zhang Jinli
School of Chemistry and Chemical Engineering, State Key Laboratory Incubation Base for Green Processing of Chemical Engineering, Shihezi University Shihezi 832003 China
School of Chemical Engineering and Technology, Tianjin University Tianjin 300072 China.
RSC Adv. 2023 Mar 9;13(12):7877-7885. doi: 10.1039/d3ra00772c. eCollection 2023 Mar 8.
Removal of carbonaceous impurities from trichlorosilane (SiHCl) reduces the carbon content of solar grade polysilicon produced with the improved Siemens method. The separation of chlorodimethylsilane (CH)SiHCl from SiHCl by distillation remains challenging due to the small difference in their boiling points. Herein, the chlorination of (CH)SiHCl/SiHCl with metal chlorides (WCl, MoCl) were studied. The aim was to convert (CH)SiHCl into (CH)SiCl, increase the relative volatility of (CH)SiHCl and SiHCl and facilitate the distillation. The optimum reaction conditions were 60 °C, 60 min and (WCl or MoCl): (SiHCl or (CH)SiHCl) = 0.7 at 0.8 MPa. Under these conditions, and when WCl and MoCl were used as the chlorine sources, the extents of (CH)SiHCl conversion were 22.7 and 18.5 times higher than those of SiHCl, respectively. In addition, a mechanistic study showed that the difference between the reactions of SiHCl and (CH)SiHCl resulted from the different energy barriers for the reactions of the and (CH)SiCl· radicals with WCl or MoCl , and the barrier for the reaction was higher than that for the (CH)SiCl· reaction.
从三氯硅烷（SiHCl）中去除碳质杂质可降低采用改进西门子法生产的太阳能级多晶硅的碳含量。由于二甲基氯硅烷（CH）SiHCl与SiHCl的沸点差异较小，通过蒸馏将二者分离仍具有挑战性。在此，研究了用金属氯化物（WCl、MoCl）对（CH）SiHCl/SiHCl进行氯化反应。目的是将（CH）SiHCl转化为（CH）SiCl，提高（CH）SiHCl与SiHCl的相对挥发度并便于蒸馏。最佳反应条件为60℃、60分钟，在0.8MPa下（WCl或MoCl）：（SiHCl或（CH）SiHCl）=0.7。在这些条件下，当使用WCl和MoCl作为氯源时，（CH）SiHCl的转化率分别比SiHCl高22.7倍和18.5倍。此外，机理研究表明，SiHCl与（CH）SiHCl反应的差异源于和（CH）SiCl·自由基与WCl或MoCl反应的不同能垒，且反应的能垒高于（CH）SiCl·反应的能垒。
