A kinetic approach to the catalytic oxidation of mercury in flue gas

Four mercury oxidation catalysts were tested in a packed bed reactor in the presence of flue gas generated by the NETL 500 lb/h coal combustor. The four catalysts tested were Ir, Ir/ HCl, Darco FGD activated carbon, and Thief/ HCl. The Thief/ HCl and Darco converted the highest percentage of the inlet mercury; however, the high conversion in these experiments was aided by larger catalyst loadings than in the Ir and Ir/ HCl experiments. We propose a method for analyzing mercury oxidation catalyst results in a kinetic framework using the bulk reaction rate for oxidized mercury formation normalized by either the catalyst mass or surface area. Results reported for fractional mercury oxidation are strongly influenced by the specific experimental conditions and are therefore difficult to translate from experiment to experiment. The catalyst- normalized results allow for more quantitative analysis of mercury oxidation catalyst data and are the first step in creating a predictive model that will allow for efficient scaling up from laboratory- scale to larger- scale studies.