Catalytic reduction of SO2 to elemental sulfur with methane over CuOx/γ-Al2O3 catalysts
Mahnaz Pourkhalil, Alimorad Rashidi, Zohal Safaei Mahmoudabadi, Majid Mirzaee, Ensieh Ganji Babakhani, Majid Esmaeili, Soheila Sharafinia
Abstract
Copper oxide catalysts (CuOx) supported on gamma alumina (γ-Al 2 O 3 ) were employed for the catalytic reduction of sulfur dioxide (SO 2 ) to elemental sulfur by methane (CH 4 ). 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-Al 2 O 3 . This study aimed to investigate the impact of reaction temperature (T = 600–800 °C) and Cu loading (0–15 wt%) on SO 2 conversion and sulfur selectivity. Under the reaction conditions of 800 °C, 1 bar, SO 2 = 5000 ppm, CH 4 = 2500 ppm, gas hourly space velocity (GHSV) = 12,000 1/h, and 10 wt% Cu, the SO 2 conversion and sulfur selectivity were determined to be 95% and 94.5%, respectively. The influence of the molar feed ratio of SO 2 /CH 4 = 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 SO 2 reduction with an excess of CH 4 , but sulfur selectivity slightly decreased as a result of the formation of unwanted byproducts such as H 2 S and COS. Conversely, when R > 2, SO 2 conversion significantly declined, while sulfur selectivity was enhanced due to increased consumption of CH 4 .