An expanded reaction kinetic model of the CuO surface-mediated formation of PCDD/F from pyrolysis of 2-chlorophenol.
An expanded reaction kinetic model, including 17 surface reactions, is proposed to explain the yields of PCDD/F obtained in an experimental study of the reaction of 2-chlorophenol over a CuO/silica surface. The mechanism is loosely based on the gas-phase mechanism for PCDD/F formation widely discussed in the literature. The principal differences are the impact of chemisorption of 2-chlorophenols to metal oxides on radical formation and the steric hindrance of oxygen-centered radicals on the surface inhibiting radical-radical reaction pathways that lead to formation of dibenzo-p-dioxin (DD). Gas-phase molecule-surface-bound adsorbate reactions are the preferred route of DD formation, while radical-radical surface reactions are the main channel for dichloro-dibenzofuran (DCDF) formation. These results suggest that the Langmuir-Hinshelwood (LH) mechanism, involving radical-radical surface reactions, and the Eley-Rideal mechanism, involving a gas-phase molecule and surface-bound adsorbate, are responsible for PCDF and PCDD formation on surfaces, respectively. The calculated yields of DCDF and DD are in reasonable agreement with experimental results.
Khachatryan
Lavrent
L
Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.
Lomnicki
Slawo
S
Dellinger
Barry
B
D001572:Benzofurans / Q000737:chemistry*; D002384:Catalysis; D002733:Chlorophenols / Q000737:chemistry*; D003198:Computer Simulation; D003300:Copper / Q000737:chemistry*; D000072338:Dibenzofurans, Polychlorinated; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods*
D001572:Benzofurans; D002733:Chlorophenols; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D003300:Copper; C030683:2-chlorophenol; C030973:cupric oxide