Mechanism and Direct Kinetic Study of the Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Formations from the Radical/Radical Cross-Condensation of 2,4-Dichlorophenoxy with 2-Chlorophenoxy and 2,4,6-Trichlorophenoxy

作者：Xu, Fei; Yu, Wanni; Zhou, Qin; Gao, Rui; Sun, Xiaoyan; Zhang, Qingzhu^*; Wang, Wenxing

来源：Environmental Science & Technology, 2011, 45(2): 643-650.

DOI：10.1021/es102660j

• GAS-PHASE FORMATION
• COMPLETE SERIES REACTIONS
• TRANSITION-STATE THEORY
• CHLORINATED PHENOLS
• WASTE INCINERATION
• PCDD/F FORMATION
• OXIDATION
• MODEL
• CHLOROPHENOLS
• ENTHALPIES

A direct density functional theory (OFT) kinetic calculation is carried out for the homogeneous gas-phase formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the cross-condensation of 2,4-dichlorophenoxy radical (2,4-DCPR) with 2-chlorophenoxy radical (2-CPR) and 2,4,6-trichlorophenoxy radical (2,4,6-TCPR). The possible formation mechanism is investigated and compared with the PCDD/F formation mechanism from the self-condensation of 2,4-DCPR, 2-CPR, and 2,4,6-TCPR. The rate constants and their temperature dependence of the crucial elementary reactions are computed by the canonical variational transition-state theory with the small curvature tunneling contribution over the temperature range of 600-1200 K. This study shows that the multichlorine substitutions suppress the PCDD/F formations. Because of a lack of experimental kinetic data, the present theoretical results are expected to be useful and reasonable to estimate the kinetic properties, such as the pre-exponential factors, the activation energies, and the rate constants, of the elementary reactions involved in the formation of PCDD/Fs.

• 出版日期2011-1-15
• 单位山东大学