30 A study on decomposition characteristic of mercury compounds and mercury species on the sorbents by TPD-Mass method

Abstract

Hg^0 vapor is one of the toxic substances derived from gasification and combustion of coal. Previously we have suggested that Hg^0 vapor can be removed as HgS(s) over iron based sorbents in the presence of H_2S and the Effect of HCl depended on the type of iron-based sorbents. In this study, we investigated the decomposition characteristic of mercury reagents grade compounds and mercury species on the sorbents using TPD -Mass method. From the TPD of reagent mercury compounds in He flow, the order of stability of mercury compounds upon heating was obtained as follows: HgSO_4>HgS(red)>HgO>HgS(black)>Hg_2Cl_2≈HgCl_2. From the experiments, it seemed that a very similar mercury species is formed over the Fe-based sorbnets both in presence and absence of HCl as HgS. However, the mercury species over the activated carbon (Flue gas deHg sorbent) could not be identified.