Issue 12, 2014

Dissociative adsorption of 2,3,7,8-TCDD on the surfaces of typical metal oxides: a first-principles density functional theory study

Abstract

The initial dissociative adsorption step of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) molecule on the surfaces of MgO, CaO, and CuO has been studied by density functional theory (DFT) using periodic slab models. It is found that the 2,3,7,8-TCDD molecule undergoes a similar dissociative adsorption step during the decomposition over the three metal oxide surfaces. The adsorption configuration of 2,3,7,8-TCDD first converts from a parallel mode into a vertical one, then a nucleophilic substitution process takes place, where the surface oxygen atom attacks the aromatic carbon to form a surface phenolate with the chlorine atom moving to the top of the nearest surface metal atom. The calculated apparent activation energy of the dissociation increases in the order of CuO < CaO < MgO. The reaction heat is −0.67 eV, −0.75 eV, and 0.45 eV for CuO, CaO, and MgO, respectively, suggesting the thermodynamic tendency of MgO < CuO < CaO, which parallels the trend of the nucleophilicity of surface oxygen atoms. This study suggests that metal oxides with more nucleophilic and less tightly-bonded surface oxygen atoms might be more promising for the decomposition of polychlorinated dibenzo-p-dioxins and dibenzofurans.

Graphical abstract: Dissociative adsorption of 2,3,7,8-TCDD on the surfaces of typical metal oxides: a first-principles density functional theory study

Supplementary files

Article information

Article type
Paper
Submitted
29 Nov 2013
Accepted
22 Jan 2014
First published
23 Jan 2014

Phys. Chem. Chem. Phys., 2014,16, 5553-5562

Dissociative adsorption of 2,3,7,8-TCDD on the surfaces of typical metal oxides: a first-principles density functional theory study

S. Zhao, X. Ma, Q. Pang, H. Sun and G. Wang, Phys. Chem. Chem. Phys., 2014, 16, 5553 DOI: 10.1039/C3CP55048F

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