New developments in the theory and modeling of mercury oxidation and binding on activated carbons in flue gas

A New Approach for Retaining Mercury in Energy Generation Processes: Regenerable Carbonaceous Sorbents

“…In summary, the higher mercury capture achieved by CF-Au than by CF was a consequence of the amalgamation between Au 0 and Hg 0 in the atmosphere containing 80% CO 2 and 20% N 2 . According to previous results obtained with similar materials, the mercury capture achieved with the sorbent could be a consequence of two possible mechanisms: (1) the formation of an amalgam between Au 0 (Figure 4) and Hg 0 and/or (2) the adsorption of oxidized mercury produced on the foam surface with the participation of the HCl present in the gas stream [34,[41][42][43]. In order to confirm these mechanisms, a series of experiments were carried out, in which the mercury retention capacity of CF and CF-Au was evaluated in an atmosphere free of acid gases.…”

“…In fact, in the presence of SO 2 and HCl (Figure 5), the retention capacity increased, and then remained constant over a number of cycles ( Figure 5). Some studies [34,[41][42][43] claim that the retention of Hg 0 in carbon materials is favored by the presence of HCl in the gas stream, which is explained by the following reactions:…”

Influences of acidic/oxidizing gases on elemental mercury adsorption equilibrium and kinetics of sulfur-impregnated activated carbon

“…On the contrary, HCl and O 2 can enhance both the oxidation and adsorption of Hg 0 . Olson et al [20] proposed a detail mechanism to describe that graphene carbon edge sites can act as the precursors of active sites for Hg 0 oxidation. The interactions between flue gas components such as HCl and NO 2 and the carbon basic zigzag sites can subsequently influence the formation of carbon-Hg covalent bond.…”

Mercury chemistry on brominated activated carbon

“…They concluded that Hg was expected to bind on the chlorinated and brominated sites of carbon and even in some cases mercury-sulfate species were expected to form due to the presence of sulfur dioxide (SO 2 ) in the flue gas. Olson et al [7] suggested that acidic sites on the surface are responsible for Hg 0 capture on AC. They propose that Hg 0 has the propensity to be oxidized by donating its electrons to a surface or another gas-phase molecule; therefore, in its elemental state, Hg 0 acts as a Lewis base with the desire to interact with an acidic site forming a strong C-Hg covalent bond on the carbon surface.…”