(73a) Heterogeneous Elemental Mercury Oxidation Kinetics over RuO2/TiO2 Catalyst | AIChE

(73a) Heterogeneous Elemental Mercury Oxidation Kinetics over RuO2/TiO2 Catalyst


Liu, Z. - Presenter, University of Cincinnati
Sriram, V., University of Cincinnati
Li, C., University of Cincinnati
Lee, J. Y., University of Cincinnati
We have developed a RuO2/rutile TiO2 catalyst, which is highly active for Hg(0) oxidation at typical SCR unit temperatures of 300-400 °C. In our previous study, the experimental evidence of dissociative HCl adsorption on the RuO2/rutile TiO2 catalyst surface under reaction conditions was obtained using an in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). In this study, heterogeneous Hg(0) oxidation kinetics over the RuO2/rutile TiO2 catalyst was investigated using a fixed-bed system in a temperature range of 300 to 400 °C under a steady-state condition. A kinetic model was developed based on our in-situ DRIFTS study results suggesting an Eley-Rideal mechanism and dissociative HCl adsorption in order to determine the reaction rate constant, activation energy, adsorption equilibrium constants and enthalpy of adsorption of HCl, NH3 and SO2. The activation energy value determined for the reaction was a low end value for the heterogeneous Hg(0) oxidation reaction using HCl gas reported in the literature, indicating the effectiveness of the RuO2/rutile TiO2 catalyst. The equilibrium adsorption analysis was used to determine the intrinsic reaction rate expression for Hg(0) oxidation kinetics with HCl under the competitive adsorption of NH3 and SO2. The kinetic expression could reasonably predict the Hg(0) oxidation performance under the competitive adsorption of NH3 and SO2 gases. The intrinsic kinetic expression obtained for the RuO2/rutile TiO2 catalyst is expected to be applicable to the design of an Hg(0) catalyst that can be installed at the tail end of a typical SCR unit.