KINETIC BEHAVIOR OF ELEMENTAL MERCURY SORPTION ON CERIUM- AND LANTHANUM-BASED COMPOSITE OXIDES

The kinetic behavior of gas phase mercury sorption on ZSM-5 supported cerium- and lanthanum-based composite oxides in the temperature range of 120-240 degrees C is investigated. The Hg-0 sorption abilities all first increase and then decrease with the elevation of the temperatures, the cerium-based composite oxides show better Hg-0 sorption abilities than that of the lanthanum-based composite oxides. CeO2-Mn2O3/ZSM-5 performs the best Hg-0 sorption ability with Hg-0 removal efficiency of nearly 100% at 180 degrees C. Doping Cu or Mn into La2O3 lattice causes the decrease in the Hg-0 removal efficiency of the lanthanum-based composite oxides due to the formation of perovskite or perovskite-like compounds. The sorption of elemental mercury over metal oxides is governed both by diffusion processes as well as chemical reactions, and the sorption of elemental mercury on the cerium- and lanthanum-based composite oxides are chemisorption processes.