Mercury oxidation by copper oxides in combustion flue gases

The two main gaseous mercury species in combustion flue gas are elemental mercury (Hg0) and oxidized mercury (Hg2+). In the coal combustion process using an installed wet FGD system, Hg2+ is captured and Hg0 emitted since Hg2+ is soluble in water. Oxidation of Hg0 upstream of the FGD would significantly reduce Hg emission. In the presence of CuO nanoparticles, oxidation of Hg0 to Hg2+ proceeded under low HCl concentration in a simulated combustion flue gas. This paper describes the effects of reaction temperature, catalyst particle size, area velocity on mercury oxidation with CuO particles and the performance demonstration of CuO mercury oxidation with actual combustion flue gases.In simulated combustion flue gases, the conversion of Hg0 to Hg2+ increased as the reaction temperature decreased, but the conversion decreased as the particle size increased. Mercury oxidation with CuO nanoparticles of 50 nm in diameter was not significantly affected by area velocity in the range of 47 to 235 m3/(h m2), but the mercury oxidation with CuO particles of 1.1 μm was decreased over 100 m3/(h m2).In an actual combustion flue gas, CuO nanoparticles showed mercury oxidation as in the case with the simulated coal combustion flue gas.

Graphical abstractAfter mercury oxidation test with CuO in the simulated combustion flue gas, the effects of the temperature, the particle size, and the area velocity on the mercury oxidation were clarified. In an actual combustion flue gas, CuO nanoparticles showed mercury oxidation as in the case with the simulated coal combustion flue gas.Figure optionsDownload full-size imageDownload as PowerPoint slide