Characteristics of the removal of mercury vapor in coal derived fuel gas over iron oxide sorbents

摘要

The characteristics of a novel method for Hg removal using H_2S and sorbents containing iron oxide were studied. Previously, we have suggested that this method is based on the reaction of Hg and H_2S over the sorbents to form HgS. However, the reaction mechanism is not well understood. In this work, the characteristics of the Hg removal were studied to clarify the reaction mechanism. In laboratory made sorbents containing iron oxide were used as the sorbent to remove mercury vapor from simulated coal derived fuel gases having a composition of Hg (4.8 ppb), H_2S (400 ppm), CO (30 percent), H_2 (20 percent), H_2O (8 percent), and N_2 (balance gas). The following results were obtained: (1) The presence of H_2S was indispensable for the removal of Hg from coal derived fuel gas; (2) Hg was removed effectively by the sorbents containing iron oxide in the temperature range of 60-100 deg C; (3) The presence of H_2O suppressed the Hg removal activity; (4) The presence of oxygen may play very important role in the Hg removal and; (5) Formation of elemental sulfur was observed upon heating of the used sample.