透氧膜法由SiO_2直接制备Si

Direct preparation of Si from SiO_2 by SOM process

为改变硅生产工艺高污染、高能耗的现状,研究了在CaCl2熔盐中利用固体透氧膜法(SOM)直接电解SiO2制备单质Si,考察了电解电压、电解时间、熔盐温度等参数对电解效果的影响,采用电子扫描显微镜和X射线衍射分析了电解产物形貌及相组成.结果表明:1100℃熔盐中,3.5 V电压下电解2 h,可制得纯Si,电流效率为89%,能耗为15 kW.h/kg;电解中间产物相分析表明,电解过程中有CaSiO3生成,CaSiO3脱氧生成Ca、Si;相比FFC法,SOM法可缩短50%反应时间,因此具有更好的工业化应用前景.

To solve the problem of high environmental impact and high energy consumption in Si industry, electrochemical reduction of solid SiO2 to prepare Si by SOM process was carried out in molten salt. The influences of electrolysis parameters such as reduction time, cell voltage, molten salt temperature on the product were investigated and the micro-structural characteristics and phase composition of the products was examined by SEM and XRD. The results showed that the SiO2 was completely reduced to Si after electrolyzed for 2 h at 3.5 V in 1 100℃ molten CaC12 , and the current efficiency was 89% , the electrolysis energy consumption was as low as 15 kW · h/kg. There was CaSiO3formed during electrolysis, and it was deoxidized to Ca and Si finally. The SOM process reduced 50% reaction time compared with FFC process, so that it might have a bright future for industrial application.