Cobalt oxide-alumina catalysts for the methane-assisted selective catalytic reduction of SO(2) to sulfur

Preventing emission of pollutants in any kind, is a way to protect global environment. The objective of this study is to develop cobalt catalysts supported on alumina for the conversion of the toxic gas SO(2) into elemental sulfur using methane. Although several useful catalysts have been proposed, there is still a need to synthesize a catalyst with a high sulfur yield that is also persistent during on-stream stability. To this end, four different catalysts were prepared using the wet impregnation technique, with Co(3)O(4) content ranging from 0 to 15 wt%. Catalytic activity tests were carried out at atmospheric pressure and temperatures ranging from 550 to 800 °C. The Al(2)O(3)–Co (15 %) catalyst exhibited superior performance, with a sulfur yield of 98.1 % at 750 °C. The catalytic stability of the best catalyst was examined using a 20 h on-stream stability test under the optimized conditions including an SO(2)/CH(4) molar feed ratio of 2 at 750 °C. The structural changes of the used catalyst after the stability test were investigated using XRD and TPO analyses. It was revealed that sulfidation of Co(3)O(4) after a short while, results in decreasing the sulfur yield from 98.1 % to 89.8 %.