Removal of gaseous mercury in flue gas by waste NOx catalyst

Abstract

Focusing on the ability of NOx catalyst to oxidize and capture mercury, we investigated the effects of components of waste and fossil fuel combustion exhaust gases on oxidation and capture ability of NOx catalyst. Experiments were conducted on the oxidation and capture of gaseous elemental mercury by filling a quartz reaction tube with pulverized NOx catalyst powder. The results showed that while mercury was captured even in a nitrogen atmosphere, the mercury capture performance was greatly enhanced when oxygen was present in the atmosphere. This indicates that the immobilization of mercury by oxidation reaction contributes to mercury capture. On the other hand, in the presence of gas containing HCl, mercury was oxidized and released in the gas phase. Exposure of the catalyst to HCl-containing gases after mercury capture resulted in oxidation and rapid desorption of the captured mercury.