Catalytic oxidation of gas-phase elemental mercury by nano-Fe2O3

Heterogeneous oxidation of gas-phase Hg-0 by nano-Fe2O3 was investigated on a fixed bed reactor, and the effects of oxygen concentration, bed temperature, water vapour concentration and particle size have been discussed. The results showed that Hg-0 could be oxidized by active oxygen atom on the surface of nano-Fe2O3 as well as lattice oxygen in nano-Fe2O3. Among the factors that affect Hg-0 oxidation by nano-Fe2O3, bed temperature plays an important role. More than 40% of total mercury was oxidized at 300 degrees C, however, the test temperature at 400 degrees C could cause sintering of nano-catalyst, which led to a lower efficiency of Hg-0 oxidation. The increase of oxygen concentration could promote mercury oxidation and led to higher Hg-0 oxidation efficiency. No obvious mercury oxidation was detected in the pure N-2 atmosphere, which indicates that oxygen is required in the gas stream for mercury oxidation. The presence of water vapour showed different effects on mercury oxidation depending on its concentration. The lower content of water vapour could promote mercury oxidation, while the higher content of water vapour inhibits mercury oxidation.