title: A simple kinetic model of PCDD/F formation by de novo synthesis.
abstract: A simple fixed-bed reactor model is used to describe experimental data about the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from fly ash carbon. The heterogeneous oxidation of graphite-like carbon is represented by a reaction which is first order in carbon and one half order in oxygen. The same orders of reaction are assumed to be valid for PCDD/F formation, such that the oxidation of fly ash carbon would have three parallel channels leading to COx, PCDD and PCDF. In addition, PCDD/F degradation by oxygen is considered and appropriate rate constants were fitted to simulate the experimental data. The effects of water vapour and particulate copper on PCDD/F formation are included. As a result, an overall kinetic model of PCDD/F formation is obtained which describes most of the experimental data with reasonable accuracy. The main reaction channel, COx formation, needs to be understood more completely, in order to interpret PCDD/F reaction pathways better. The model can be extended to include other chlorinated aromatics and the gas/particle partitioning of the semivolatiles. It provides a basis for the qualitative and quantitative interpretation of fixed-bed and flow reactor results and it is hoped to be applicable to industrial installations like waste incinerators and metal smelters.
authors.affiliation: Forschungszentrum Karlsruhe GmbH, Institut für Technische Chemie, Bereich Thermische Abfallbehandlung, Germany. maetzing@itc-tab.fzk.de
authors.forename: H
authors.initials: H
authors.lastname: Mätzing
mesh_terms: D001572:Benzofurans / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D017745:Incineration; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry*; D012037:Refuse Disposal; D012989:Soil Pollutants / Q000032:analysis*; D014835:Volatilization
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D002244:Carbon; D010100:Oxygen