Catalytic Reduction of SO2 with CH4 to Elemental Sulfur: A Comparative Analysis of Alumina, Copper-Alumina, and Nickel-Alumina Catalysts

The catalytic reduction of sulfur dioxide with methane to form elemental sulfur was studied. Al2O3, Cu-Al2O3, and Ni-Al2O3 were examined as catalysts whose performances were compared in terms of SO2 conversion and selectivity. Performance of the catalyst extremely improved when nickel and copper were added as promoters. The effects of temperature, SO2/CH4 molar ratio, and reaction time on SO2 reduction were studied. The operating temperature range was 550–800 °C, and it was observed that the reaction was strongly temperature dependent. At temperatures lower than 700 °C, Al2O3-Cu (10 %) catalyst showed the best performance of all the catalysts. However, at 700 °C and higher, performances of Al2O3-Cu (10 %) and Al2O3-Ni (10 %) catalysts were similar. Complete conversion and selectivity (more than 99.5 %) was achieved by Al2O3-Cu (10 %) and Al2O3-Ni (10 %) catalyst, at 750 °C. Effect of molar feed ratio of SO2/CH4= 1-3 was studied, and stoichiometric feed ratio showed the best performance. In addition, the investigation of reaction time for Al2O3- Cu (10 %) and Al2O3-Ni (10 %) catalysts showed good long-term stability for SO2 reduction with methane.