title: Metal-mediated chlorinated dibenzo-p-dioxin (CDD) and dibenzofuran (CDF) formation from phenols.
abstract: Heterogeneous formation of chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) on CuCl2 from three phenols without ortho chlorine and one phenol with two ortho chlorines was studied in a flow reactor over a temperature range of 325-450 degrees C. Heated nitrogen gas streams containing 8% oxygen, 1.5% benzene vapor, and equal amounts of phenol, 3-chlorophenol, 3,4-dichlorophenol and 2,4,6-trichlorophenol vapor (700 ppmv, each) were passed through a 1 g particle bed of silica and 0.5% (Cu mass) CuCl2. Maximum product yields of greater than 1.4% phenol conversion to CDD and 5.7% phenol conversion to CDF were observed between 400 and 450 degrees C. CDDs formed with loss of one chlorine atom were favored. While total CDD/F yield varied with temperature, CDD/F homologue and isomer distributions did not vary significantly with temperature. Based on the results of experiments with single phenol precursors, phenol precursors could be assigned to all PCDD/F products. Of the chlorinated phenols without ortho chlorine that were studied, 3,4-dichlorophenol was found to have the greatest propensity to form CDFs.
authors.affiliation: Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0512, USA.
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Ryu
authors.forename: James A
authors.initials: JA
authors.lastname: Mulholland
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D004147:Dioxins / Q000737:chemistry*; D017745:Incineration; D010636:Phenols / Q000737:chemistry*; D013696:Temperature; D014835:Volatilization
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D004147:Dioxins; D010636:Phenols; D002713:Chlorine; D003300:Copper