Halogen-containing aromatics, mainly bromine-containing phenols are harmful compounds contaminating pyrolysis oil from electronic boards containing halogenated flame retardants. In addition, their formation increases the potential for evolution of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs) at relatively low temperature (up to 500 °C). As a model compound, 2,4-dibromophenol (DBP), was pyrolyzed at 290 – 450 °C. While its pyrolysis in a nitrogen flow reactor or in encapsulated ampoules yields bromine-containing phenols, phenoxyphenols, PBDDs and PBDFs, pyrolysis of DBP in a hydrogen-donating media of polypropylene (PP) at 290 – 350 °C mainly results in the formation of phenol and HBr, indicating the occurrence of a facile hydrodebromination of DBP. The hydrodebromination efficiency depends on temperature, pressure and the ratio of the initial components. This thermal behavior of DBP is compared to that of 2,4-dichlorophenol and decabromodiphenyl ether. A treatment of halogen-containing aromatics with PP offers new perspective of the development of low-environmental impact disposal processes for electronic scrap.
Pyrolysis study of 2,4-dibromophenol reflecting reactions with PP in a post-treatment decontamination process
LUDA DI CORTEMIGLIA, Maria Paola;
2005-01-01
Abstract
Halogen-containing aromatics, mainly bromine-containing phenols are harmful compounds contaminating pyrolysis oil from electronic boards containing halogenated flame retardants. In addition, their formation increases the potential for evolution of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs) at relatively low temperature (up to 500 °C). As a model compound, 2,4-dibromophenol (DBP), was pyrolyzed at 290 – 450 °C. While its pyrolysis in a nitrogen flow reactor or in encapsulated ampoules yields bromine-containing phenols, phenoxyphenols, PBDDs and PBDFs, pyrolysis of DBP in a hydrogen-donating media of polypropylene (PP) at 290 – 350 °C mainly results in the formation of phenol and HBr, indicating the occurrence of a facile hydrodebromination of DBP. The hydrodebromination efficiency depends on temperature, pressure and the ratio of the initial components. This thermal behavior of DBP is compared to that of 2,4-dichlorophenol and decabromodiphenyl ether. A treatment of halogen-containing aromatics with PP offers new perspective of the development of low-environmental impact disposal processes for electronic scrap.
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