Metal chlorides loaded on activated carbon to capture elemental mercury
Zhemin Shen , Jing Ma , Zhijian Mei , Jianda Zhang
DOI:
Received November 11, 2009,Revised April 16, 2010, Accepted , Available online
Volume 22,2010,Pages 1814-1819
- Summary
- References
- Related Articles
Activated carbon (AC) was considered to be an effective sorbent to control mercury in combustion systems. However, its capture
capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury (Hg0)
capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal
oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC
to remove gaseous mercury. X-ray diffractometer (XRD), thermogravimetric analyzer (TGA) and specific surface area by Brunauer-
Emmett-Teller method (BET) analysis showed the main mechanisms: first, AC had an enormous surface area for loading enough
MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and
MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl2 might be
released from AC’s porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process
of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg0 oxidization may accelerate
both oxidation and halogenation of Hg0. The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect
of valence variable metal and chlorine oxidation.
