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  • Catalytic effect of CuO and other transition metal oxides in formation of dioxins: theoretical investigation of reaction between 2,4,5-trichlorophenol and CuO.

Catalytic effect of CuO and other transition metal oxides in formation of dioxins: theoretical investigation of reaction between 2,4,5-trichlorophenol and CuO.

Environmental science & technology (2007-09-19)
Qiao Sun, Mohammednoor Altarawneh, Bogdan Z Dlugogorski, Eric M Kennedy, John C Mackie
ABSTRACT

Density functional theory (DFT) calculations have been carried out to explore the potential energy surface (PES) associated with the gas-phase reaction between 2,4,5-trichlorophenol and CuO. A gas-phase model was constructed to account, from a theoretical perspective, for the most important reaction steps reported experimentally for the interaction between chlorinated phenol and a CuO surface. This involves the facile production of the chlorophenoxy radical through hydroxyl H abstraction, formation of HOCu-2,4,5-trichlorophenolate complex, and reduction of Cu-(II) into Cu(I) through chlorophenoxy desorption from the chlorophenolate complex. The overall process: 2,4,5-trichlorophenol + CuO --> 2,4,5-trichlorophenoxy radical + CuOH is significantly exothermic and facile (unlike the strongly endothermic process of 2,4,5-trichlorophenol --> 2,4,5-trichlorophenoxy radical + H) suggesting that in the gas phase, at least, CuO would be an efficient catalyst for production of polychlorinated phenoxy radicals which are known precursors of dioxins. Hence, the present study should be an important preliminary to a detailed investigation of the efficacy of CuO surfaces toward catalysis of dioxin formation. Lastly, we estimate the reaction energies for the reaction 2,4,5-trichlorophenol + MO --> 2,4,5-trichlorophenoxy radical + MOH for the first-row transition metal monoxides. This reaction only becomes exothermic for elements which have at least a half-filled d shell. Although the results of the present thermodynamic analysis match the observed catalytic effect toward dioxin formation, kinetic considerations are expected to play a major role as well.

MATERIALS
Product Number
Brand
Product Description

Supelco
2,4,5-Trichlorophenol, PESTANAL®, analytical standard
Sign Into View Organizational & Contract Pricing
SKUVendor SKUPack SizeAvailabilityPrice
EN300-15940-100MG100 mg
Ships in 14 days - from Aldrich Partner.
CHF 237.40
EN300-15940-250MG250 mg
Ships in 14 days - from Aldrich Partner.
CHF 319.30
EN300-15940-500MG500 mg
Ships in 14 days - from Aldrich Partner.
CHF 568.90
EN300-15940-1G1 g
Ships in 14 days - from Aldrich Partner.
CHF 715.80
EN300-15940-2.5G2.5 g
Ships in 14 days - from Aldrich Partner.
CHF 1,360.60

To order products, please contact your local dealer.

Sigma-Aldrich
2,4,5-Trichlorophenol, 95%
Sign Into View Organizational & Contract Pricing
SKUVendor SKUPack SizeAvailabilityPrice
EN300-15940-100MG100 mg
Ships in 14 days - from Aldrich Partner.
CHF 237.40
EN300-15940-250MG250 mg
Ships in 14 days - from Aldrich Partner.
CHF 319.30
EN300-15940-500MG500 mg
Ships in 14 days - from Aldrich Partner.
CHF 568.90
EN300-15940-1G1 g
Ships in 14 days - from Aldrich Partner.
CHF 715.80
EN300-15940-2.5G2.5 g
Ships in 14 days - from Aldrich Partner.
CHF 1,360.60

To order products, please contact your local dealer.

Sigma-Aldrich
2,4,5-Trichlorophenol, purum, ≥95.0% (GC)
Sign Into View Organizational & Contract Pricing
SKUVendor SKUPack SizeAvailabilityPrice
EN300-15940-100MG100 mg
Ships in 14 days - from Aldrich Partner.
CHF 237.40
EN300-15940-250MG250 mg
Ships in 14 days - from Aldrich Partner.
CHF 319.30
EN300-15940-500MG500 mg
Ships in 14 days - from Aldrich Partner.
CHF 568.90
EN300-15940-1G1 g
Ships in 14 days - from Aldrich Partner.
CHF 715.80
EN300-15940-2.5G2.5 g
Ships in 14 days - from Aldrich Partner.
CHF 1,360.60

To order products, please contact your local dealer.