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

Abstract

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 SiCl4, the SiC was converted to SiCl4 and porous carbon, and the Fe was converted to FeCl3. 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 SiCl4 was 99.7% and the surface area of the resulting carbon was 860 m2/g. The surface area was invariable as the temperature was further increased to 1200 °C.