The role of bromine in the de novo synthesis in a model fly ash system

Abstract

The role of bromine in de novo synthesis in a model fly ash system. Luijk, R.; Dorland, C.; Smit, P.; Jansen, J.; Govers, H.A.J. Published in: Chemosphere DOI:10.1016/0045-6535(94) Link to publication Citation for published version (APA):Luijk, R., Dorland, C., Smit, P., Jansen, J., & Govers, H. A. J. (1994). The role of bromine in de novo synthesis in a model fly ash system. Chemosphere, 28(7), 1299-1309. DOI: 10.1016/0045-6535(94)90074-4 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 10 May 2018Pergamon 0045-6535(94)E0062-X Chemosphere, Vol. 28, No. 7, pp. 1299-1309, 1994 Copyright © 1994 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0045-6535/94 $7.004-0.00 THE ROLE OF BROMINE IN THE DE NOVO SYNTHESIS IN A MODEL FLY ASH SYSTEM ABSTRACTThe role of bromine in the de novo synthesis in a model fly ash system has been evaluated. A silica-alumina carrier was impregnated with a CuX7 catalyst system (X=C1, 0.5 wt%; X=Br, 0.8 wt%). A flow of air with 5 vol. % I-IX (X=C1 or Br) was passed over a fixed bed at 300°C. Several processes have been investigated concerning the role of bromine and chlorine in the formation of polyhalogenated dibenzo-p-dioxins and -dibenzofurans in municipal waste incinerator fly ash under conditions observed in an electrostatic precipitator:The exchange of bromine and chlorine in 2,3,7,8-tetrabromodibenzo-p-dioxin; The reactivity and selectivity of bromine and chlorine in the halogenation of the parent structures dibenzo-p-dioxin and dibenzofuran;The competition of bromine and chlorine in the de novo synthesis. INTRODUCTIONThe last decade several studies about the formation of polybrominated dibenzo-p-dioxins and -dibenzofurans (PBDDs and PBDFs) during thermal degradation of polymers containing brominated flame retardants have been published [1,2]. Also the presence of mixed brominate~chlorinated dibenzo-p-dioxins and -dibenzofurans (PXDDs and PXDFs with X=C1, Br) in municipal waste incinerator fly ash has been shown [3,4]. However, the analysis of PBDD/PBDFs and the mixed halogenated PXDD/PXDFs (X=CI, Br) is accompanied with difficulties. The physico-chemical properties of polybrominated compounds, i.e. high molecular weight, high melting point, low vapour pressure and low thermal stability requires a sop...

Reactions of Dibenzofuran and 1,2,3,4,7,8-Hexachlorodibenzo-p- dioxin on Municipal Waste Incinerator Fly Ash

“…Chlorination reactions of DF on Al 2 O 3 -SiO 2 with HCl at 300°C yield mainly 2,3,7,8-substituted congeners; the route of chlorination is 2 f 8 f 3 f 7 f 1 f 4 f 6 f 9 (9). This order of chlorination is consistent with an electrophilic aromatic substitution mechanism.…”

Mechanisms of Formation and Destruction of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Heterogeneous Systems

“…DD/F can be chlorinated by CuCl2 on Si02Al203 (52). Both OCDD and OCDF can be dechlorinated by A1203 without a catalyst (70,71).…”

Distributions, profiles and formation mechanisms of polychlorinated naphthalenes in cement kilns co-processing municipal waste incinerator fly ash

“…It has been suggested, from theoretical calculations and experimental studies, that chlorination occurs much more easily at the b positions than at the a positions of a PCN molecule (Luijk et al, 1994;Zhai and Wang, 2005;Jansson et al, 2008). The main difference between the PCN congener patterns found in samples from the head and back ends of the kilns was that…”