(45c) Assessing Mercury Oxidation Performance of Au-Based Oxidation Catalysts

Due to imminent EPA regulations regarding trace metal release from coal-fired utility boilers, it is imperative that methods for their capture are developed. A major focus of research is aimed at analyzing possible mercury capture processes, which include indirect capture via oxidation or direct capture via adsorption. The current research is on establishing the oxidation performance of gold catalysts, through the use of a bench-scale packed-bed reactor and surface element characterization methods such as X-Ray Photoemission Spectroscopy. The adsorption of mercury on these catalysts is also investigated since it has been found that some level of adsorption occurs before steady-state oxidation is achieved. To simulate the flue gas methane is burned in air with SO₂ and NOx components doped into the stream after the flame. Analysis of oxidation behavior in the presence of halogens such as Cl₂ and Br₂ will play a vital role in identifying surface reaction mechanisms of flue gas streams with catalyst beds, which is currently an area of much debate. Halogen species are introduced along with Hg into the flame to ensure the presence of short-lived radical species, which are known to play a vital role in mercury oxidation in coal-fired utility boiler. Experimental results will be compared with calculations from density functional theory also generated as part of our research initiative in order to elucidate the mechanism of mercury oxidation across these catalyst surfaces. We will also examine the dispersion of the noble metal catalyst on TiO₂, and α- and γ-Al₂O₃ supports in order to better understand the surface interactions occurring on the surface during the oxidation process. Mercury pollution from coal-fired utilities is of major concern, and development in this area of technology will play a vital role in minimizing the impact of future coal-generated electricity.