A Kinetic Investigation of High-Temperature Mercury Oxidation by Chlorine

Abstract

First-stage mercury oxidation reactions typical of coal combustion flue gases were investigated. The present study is a determination of the kinetic and thermodynamic parameters of the bimolecular reactions, Hg + Cl 2 T HgCl + Cl, Hg + HCl T HgCl + H, and Hg + HOCl T HgCl + OH, at the B3LYP/RCEP60 VDZ level of theory over a temperature range of 298.15 to 2000 K at atmospheric pressure. Conventional transition state theory was used to predict the forward and reverse rate constants for each reaction and ab initio based equilibrium constant expressions were calculated as a function of temperature. Reasonable agreement was achieved between the calculated equilibrium constants and the available experimental values.

Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces

“…Also, B3PW91/RCEP60VDZ combination provides reasonably accurate results for these systems B3LYP/LANL2DZ combination is not enough accurate. RCEP60VDZ is the basis set that uses a relativistic compact effective potential of Stevens et al group [22], which replaces 60 of mercury's atomic core electrons, derived from numerical Dirac-Fock wavefunctions using an optimizing process based upon the energy-overlap functional [17]. The B3PW91 method of DFT is within acceptable errors for predicting geometries compared to the larger and more expensive calculation methods such as QCISD.…”

“…Progress in quantum chemical calculations has made it possible to make reliable predictions of molecular structures, relative energies, potential surfaces, reaction mechanisms, and so on. Quantum chemical methods, in the form of density functional theory, are increasingly used to understand mechanisms in both homogenous [17,18] and heterogeneous [19,20] systems.…”

Experimental study on the absorption behaviors of gas phase bivalent mercury in Ca-based wet flue gas desulfurization slurry system

“…In general, the mercury removal efficiency by wet scrubbing varied from 40 to 80% depending on the coal type and combustion conditions. Thus, most of researches were focused on the oxidation technology of Hg 0 to Hg 2+ by catalytic oxidation [14][15][16][17][18], photochemical oxidation [19][20][21] and gas-phase oxidation [22][23][24][25] to enhance its solubility, thereby improved the removal efficiency. However, little work had been conducted to identify the absorption of bivalency mercury and its reduction by the scrubber slurry.…”

Effects of Mg2+ on the bivalent mercury reduction behaviors in simulated wet FGD absorbents

“…As such, many efforts have been devoted to transfer the elemental form of mercury to oxidized form (much easier for absorption or adsorption) and there are significant oxidation technologies being developed by previous researches, including catalytic oxidation [19][20][21][22][23][24][25], photochemical oxidation [26][27][28] and gas-phase oxidation [29][30][31][32][33][34]. After the mercury is being oxidized, the wet-FGD system could provide an option for simultaneous control of SO 2 and oxidized mercury pollutions.…”