Mercury capture by a regenerable sorbent under oxycoal combustion conditions: Effect of SO2 and O2 on capture efficiency

The present study evaluates an Au/C sorbent based on the direct reduction of a gold salt on a carbon coated structured cordierite monolith for mercury capture under oxyfiring conditions. Both mercury retention efficiency and mercury retention capacity were tested in a bench scale plant under different conditions. The influence of gas temperature (50-150 degrees C) and gas composition (CO2, N-2, SO2, and O-2) on sorbent performance for mercury capture is evaluated and discussed. The amount of mercury captured did not vary significantly with temperature under a CO2 atmosphere. These results were compared with those obtained under N-2 atmosphere with no remarkable differences found between them. High retention efficiencies were obtained despite the small amount of gold used. The presence of SO2 and O-2 in the flue gas led to mercury oxidation that seemed to be mainly promoted by SO2 under the presence of the Au-sorbent. (C) 2014 Elsevier Ltd. All rights reserved.