Morphology-controlled synthesis and sulfur modification of 3D hierarchical layered double hydroxides for gaseous elemental mercury removal

Porous structure and effective active site are beneficial for gaseous elemental mercury (Hg 0 ) capture. Two kinds of hierarchical porous layered double hydroxides (LDHs) were synthesized through an in-situ growth method. Sulfur was used for the modification of these LDHs to enhance Hg 0 removal performance. Two as-prepared NiAl-S 4 @SiO 2 microspheres displayed three-dimensional morphologies, accordingly exhibited as core-shell and urchin-like morphologies. XRD , BET, FTIR, TEM and SEM were employed to investigate the structure effect on Hg 0 uptake. The results indicated that after S-modification, the Hg 0 removal efficiencies as well as SO 2 resistance were enhanced. The Hg 0 removal performances follow the order of: NiAl-S 4 @SiO 2 -urchin > NiAl-S 4 @SiO 2 -core at 100 °C. The mechanism for Hg 0 removal was discussed based on the results of TPD , EDX and XPS . The porous structure of NiAl-S 4 @SiO 2 composite was beneficial for gas transformation and intercalated [S 4 ] 2− ions were favorable for mercury uptake. The polysulfide combined with adsorbed mercury and formed HgS. Such materials exhibit promising potential for mercury uptake from S Hg mixed flue gas.