Application of gold catalyst for mercury oxidation by chlorine

This paper discusses a recent study of mercury catalytic oxidation by chlorinating reagents. Gold was chosen as the catalyst because of its reluctance to chemisorb some gases such as O-2, NO, H2O, and SO2. This property, as demonstrated in this study, is instrumental to mercury oxidation by circumventing some undesired inhibitory reactions such as OH + NO + M -> HONO + M and OH + SO2 + M -> HOSO2 + M, which were recognized under homogeneous situations at high temperatures. In comparison to Cl-2, HCl showed weak oxidizing capability but appreciable inhibition in mercury oxidation by Cl-2, probably through the competition of active sites with Cl-2. Overall, the mercury catalytic oxidation by Cl-2 on gold catalyst surfaces was viable, reaching 40-60% in this study under temperatures of 448-498 K, where the thermal decomposition of formed Hg2+ was effectively avoided.