(637b) Temperature-Programmed Desorption Investigation of Carbon-Based Sorbents Exposed to Coal Combustion Flue Gas

Activated carbon injection (ACI) technology is commercially available for control of vapor-phase mercury emissions from incineration and coal combustion flue gases. A suitable AC for this application should have a high reactivity, small particle size (<20 µm), and in some cases halogen surface functional groups. Fixed-bed carbon structure is an alternative technology which could be potentially used to capture mercury in combustion flue gases. A suitable AC for this application should have high adsorption capacity and preferably be re-generable. In this paper, the results from a study focusing on the regeneration of a sulfur-impregnated activated carbon cloth and two commercial sulfur-containing activated carbon sorbents are presented. Carbon sorbents were exposed to an actual slipstream of flue gas at a coal-fired power plant to capture vapor-phase mercury. Samples were characterized before and after exposures to flue gas. TG-MS experiments were performed to obtain temperature programmed desorption profiles of species released from the samples. In addition, XPS measurements provided the nature of the surface functional groups on carbon samples. The results were used to explain the role of activated carbon surface chemistry and pore structure on the mercury adsorption capacity and thermal regeneration performance of the carbon samples.