Heterogeneous Mercury Oxidation by HCl over CeO2 Catalyst: Density Functional Theory Study
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- 作者：Bingkai Zhang ; Jing Liu ; Fenghua Shen
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：July 9, 2015
- 年：2015
- 卷：119
- 期：27
- 页码：15047-15055
- 全文大小：493K
- ISSN：1932-7455
文摘
CeO<sub>2sub>-based catalysts have been regarded as potential materials for Hg removal due to high catalytic performance, nontoxicity, and low cost. Density functional theory calculations were performed to investigate the mercury oxidation mechanism by HCl over a CeO<sub>2sub> catalyst. The thermodynamic stability analysis suggests that the stoichiometric CeO<sub>2sub>(111) is the most stable surface. The protonated CeO<sub>2sub> surfaces takes place at low oxygen partial pressures, and the chlorinated CeO<sub>2sub> surfaces can stably exist under low HCl concentrations. The adsorption energies and geometries show that Hg<sup>0sup> is physically adsorbed on oxygen sites of the CeO<sub>2sub>(111) surface and HCl is chemically adsorbed on the CeO<sub>2sub>(111) surface. HCl can dissociate on the CeO<sub>2sub>(111) surface with a low barrier. The Hg oxidation is most likely to proceed with the Eley鈥揜ideal mechanism at the first step (Hg 鈫?HgCl), followed by the Langmuir鈥揌inshelwood mechanism at the second step (HgCl 鈫?HgCl<sub>2sub>). In the whole Hg oxidation reaction, the formation of HgCl<sub>2sub> is the rate-determining step. The low energy barriers for the oxidation reaction of Hg on CeO<sub>2sub> make it an attractive alternative catalyst for Hg oxidation.