Recycling of SiC–Si Sludge to Silicon Tetrachloride and Porous Carbon via Chlorination

A SiC–Si sludge composed of 79.4 wt % SiC, 14.2 wt % Si, and 5.06 wt % Fe was chlorinated in a tubular reactor with nitrogen as the carrier gas. The chlorination temperature was varied from 100 °C to 1200 °C, the time was varied from 1 h to 8 h, and the chlorine mole fraction was varied from 2.5% to 10.0%, while the flow rate of the carrier gas was fixed at 300 mL/min. The Si was converted to SiCl 4, the SiC was converted to SiCl 4 and porous carbon, and the Fe was converted to FeCl 3 . The Fe and Si were more reactive to chlorination than the SiC. The conversion was nearly complete at 900 °C, 4 h, and 10% chlorine. The purity of the obtained SiCl 4 was 99.7% and the surface area of the resulting carbon was 860 m 2 /g. The surface area was invariable as the temperature was further increased to 1200 °C.