Conversion of sulfur dioxide and carbon disulfide to elemental sulfur under plasma-induced conditions

CS2 and SO2 appear in industrial processes such as the Claus reaction; however, few studies have focused on both simultaneous reactions. In this study, the conversion of CS2 and SO2 into elemental sulfur proceeded efficiently, using a radio-frequency plasma-induced system. The main experimental parameters were as follows: the feeding concentration of SO2, discharge power (P), inlet CS2/SO2 ratio (R), and system pressure at room temperature. The conversions were sensitive to either P or R. When P was increased from 15 W to 120 W, the SO2 conversion only increased from 27.3% to 66.8% at [SO2] = 2% and R = 1, whereas conversion apparently increased from 26.5% to 98.2% when R = 2 ([CS2] = 4%). Interestingly, the optimum operating condition was observed at R = 2 to reach larger conversions for both SO2 and CS2, simultaneously. At R = 2, the stoichiometric ratio for C/O is 1, providing oxygen as a prior sink for the C atom, and resulting in CO as the major gaseous product; the selectivity of S-1 was 0.989 at 90 W, because most S atoms formed into elemental sulfur. The purity of sulfur reached 98.5%, and the X-ray diffraction patterns indicated great amounts of S-8 structure.