Catalytic reduction of SO2 to elemental sulfur with methane over CuOx/γ-Al2O3 catalysts

Abstract

Copper oxide catalysts (CuOx) supported on gamma alumina (γ-Al2O3) were employed for the catalytic reduction of sulfur dioxide (SO2) to elemental sulfur by methane (CH4). The catalysts were synthesized using a straightforward sol–gel method. Initially, alumina was obtained through a precipitation technique. X-ray diffraction (XRD) analysis was conducted to confirm the formation of γ-Al2O3. This study aimed to investigate the impact of reaction temperature (T = 600–800 °C) and Cu loading (0–15 wt%) on SO2 conversion and sulfur selectivity. Under the reaction conditions of 800 °C, 1 bar, SO2 = 5000 ppm, CH4 = 2500 ppm, gas hourly space velocity (GHSV) = 12,000 1/h, and 10 wt% Cu, the SO2 conversion and sulfur selectivity were determined to be 95% and 94.5%, respectively. The influence of the molar feed ratio of SO2/CH4 = R = 0.5–3 on the 10 wt% Cu catalyst was also investigated in the temperature range of 600–800 °C. The findings revealed that when R < 2, the conversion rate increased due to higher SO2 reduction with an excess of CH4, but sulfur selectivity slightly decreased as a result of the formation of unwanted byproducts such as H2S and COS. Conversely, when R > 2, SO2 conversion significantly declined, while sulfur selectivity was enhanced due to increased consumption of CH4.