Reaction and Adsorption of Mercury Captured Onto Cupric Chloride-Impregnated Sorbents

Thursday, November 11, 2010: 9:30 AM
Grand Ballroom J (Marriott Downtown)
Xin Li1, Joo-Youp Lee1 and Tim C. Keener2, (1)Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH, (2)Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH

Carbon sorbent injection is the most promising control technology in reducing mercury emissions from coal-fired power plants. CuCl2-impregnated activated carbon sorbent has demonstrated excellent mercury oxidation and adsorption performance in our previous studies. In our previous study using XAFS shows that mercuric chloride (HgCl2) is a major resultant oxidized mercury compound generated over the CuCl2-impregnated activated carbon sorbent as a result of reaction between elemental mercury and cupric chloride. This study focused on the kinetic adsorption behavior of mercuric chloride vapor onto the CuCl2-impregnated activated carbon sorbent.

The experiments were performed in our lab-scale fixed-bed system at 140 C by varying inlet HgCl2 concentrations in the range of 5~20 ppbv. Three different sorbents were tested, i.e. raw commercial activated carbon (Norit's DARCO FGD), 4%(wt) CuCl2-impregnated activated carbon, and 8%(wt) CuCl2-impregnated activated carbon. The adsorption capacities of HgCl2 onto raw, 4%, and 8% sorbents were 30 mg, 17 mg, 9 mg HgCl2 per g sorbent, respectively, at 10 ppbv HgCl2. The HgCl2 adsorption capacity of CuCl2-impregnated activated carbon decreased with an increase in CuCl2 loading, suggesting that HgCl2 is adsorbed onto free carbon site. Based on the Langmuir isotherm assumption, a kinetic model of HgCl2 adsorption onto CuCl2-impregnated AC was developed, and the adsorption and desorption rate constants were determined by fitting experimental breakthrough data with the model calculations.

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See more of this Session: Control of Metal HAP Emissions (Hg, Se, As, Cr, etc. )
See more of this Group/Topical: Environmental Division