Recovery of elemental sulphur via selective catalytic reduction of SO₂ over sulphided CoMo/γ-Al₂O₃ catalysts

This study aimed to develop sulphided CoMo/γ-Al₂O₃ catalysts to recover elemental sulphur via selective reduction and to understand the catalytic mechanism of the selective catalytic reduction (SCR) of SO₂ into sulphur when CO is used as the reducing agent. A series of catalysts were prepared based on Taguchi's L₉ orthogonal array and were evaluated in terms of their SO₂ conversion efficiency, selectivity of SO₂ reduction to elemental sulphur, elemental sulphur yield, and selectivity of COS formation. It is found that the catalyst sulphided at 400 °C with a ratio of Co/(Co + Mo) = 0.31 and supported on γ-Al₂O₃ had the best performance among all the catalysts studied. In addition, the physical-chemical properties and catalytic activities of this catalyst were studied systematically. The mechanism of selective reduction of SO₂ to elemental sulphur using CO as the reducing agent was therefore proposed.