Preadsorbed SO3 Inhibits Oxygen Atom Activity for Mercury Adsorption on Cu/Mn Doped CeO2(110) Surface

The coadsorption of Hg-0 and SO3 on pure and Cu/Mn doped CeO2(110) surfaces were investigated using the Density Functional Theory (DFT) method. A p (2 x 2) supercell periodic slab model with seven atomic layers was constructed to represent the CeO2(110) surface. The results indicated that Hg-0 physically adsorbed on the CeO2(110) surface, while Hg-0 chemically adsorbed on the Cu/Mn doped CeO2(110) surface, which agree well with the experimental results that Cu and Mn doped CeO2 greatly improved the Hg-0 adsorption capacity of the adsorbent. The calculated results suggested that SO3 more easily adsorbs on the above three surfaces than Hg-0 due to the higher adsorption energy. The adsorption configurations and electronic structures indicated SO3 reacted with O atoms of the surface to form SO42- species. Hence, SO3 inhibits Hg-0 adsorption on the CeO2(110) surface by competing with Hg-0 for surface lattice oxygen. In addition, SO3 decreased the activity of the surface O atoms, which directly caused the negative effect on Hg-0 adsorption.