HgCl 2 is directly formed by the adsorbed Cl and Hg 0 on the ZnO surface and not via HgCl intermediate. The dissociated H atoms on the ZnO surface inhibit the formation of HgCl 2. Cl 2 rather than HCl is responsible for the oxidation of... more
HgCl 2 is directly formed by the adsorbed Cl and Hg 0 on the ZnO surface and not via HgCl intermediate. The dissociated H atoms on the ZnO surface inhibit the formation of HgCl 2. Cl 2 rather than HCl is responsible for the oxidation of Hg 0 on the ZnO surface. HgCl 2 is easy to be formed via the E–R and L–H mechanisms on the ZnO surface. g r a p h i c a l a b s t r a c t 53.0 kJ/mol HgCl 2 276.0 kJ/mol 0.0 kJ/mol 0.0 kJ/mol 3.9 kJ/mol 0.0 kJ/mol a b s t r a c t The density functional theory with the generalized gradient approximation has been used to determine the binding mechanism of Cl 2 , HCl and Hg species on the ZnO(1 0 1 0) surface, and the Hg 0 oxidation mechanism by Cl 2 (or HCl) on the ZnO surface. Cl 2 and HCl are dissociatively adsorbed on the surface, and Cl atom bonds to two adjacent Zn atoms. Binding energy of Hg 0 is showing a physisorption mechanism , while HgCl 2 is strongly adsorbed on the surface in the molecularly mode, which indicates that the oxidation of Hg 0 is necessary for its removal from flue gas. HgCl is not an indispensable intermediate during the Hg 0 oxidation to form HgCl 2. Three Hg 0 oxidation mechanisms have been investigated, and the HgCl 2 is easy to be formed via both the Eley–Rideal and LangmuirÀHinshelwood mechanisms, while MarsÀMaessen mechanism is unfavorable since high activation energy is needed for Hg 0 reacting with the lattice oxygen of ZnO. The adsorbed H atoms by HCl dissociation inhibit the formation of HgCl 2 , and Cl 2 is the primary species being responsible for the Hg 0 oxidation on the ZnO surface.
