Cobalt oxide-alumina catalysts for the methane-assisted selective catalytic reduction of SO2 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 SO2 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 Co3O4 content ranging from 0 to 15 wt%. Catalytic activity tests were carried out at atmospheric pressure and temperatures ranging from 550 to 800 degrees C. The Al2O3-Co (15 %) catalyst exhibited superior performance, with a sulfur yield of 98.1 % at 750 degrees C. The catalytic stability of the best catalyst was examined using a 20 h on-stream stability test under the optimized conditions including an SO2/CH4 molar feed ratio of 2 at 750 degrees 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 Co3O4 after a short while, results in decreasing the sulfur yield from 98.1 % to 89.8 %.

Automated summary

This study aimed to develop a cobalt catalyst supported on alumina that can achieve high sulfur yield and maintain stability during usage, for the conversion of toxic gas SO2 into elemental sulfur using methane. Experimental tests revealed that the Al2O3-Co (15%) catalyst exhibited excellent catalytic performance, achieving a sulfur yield of 98.1% at 750 degrees C. However, a long-term stability test showed that sulfidation of Co3O4 occurred after a short while, resulting in a decrease in sulfur yield to 89.8%.