Experimental study of the oxidation and pyrolysis of dibenzofuran at very low concentration

“Dioxins” (or PCDD/F) are persistent organic pollutants (POP) which are emitted in the atmosphere by several combustion and thermal processes. Many studies concern the formation of dioxins, but very few thermal destruction. The present study concerns the oxidation and the pyrolysis of dibenzofuran which is chosen as a model molecule of “PCDF” (polychrorodibenzofurans). The reaction is studied at very low concentration of dibenzofuran (i.e. near 2 ppm) in a continuous perfectly stirred reactor, at atmospheric pressure. The residence time is varying between 3 s and 5 s, whereas the temperature is ranging from 500 to 950 °C. Dibenzofuran is a solid compound in standard conditions, so a difficulty of this study is to realize a continuous gas flow of this species.During dibenzofuran decomposition, the conversion can be close to 100% and several intermediary species are formed. These species are identified by GC/MS and then quantified by GC/FID. The main byproducts are derivatives of benzofuran, polyaromatic hydrocarbons and other volatile organic compounds. These experimental data are used to improve a kinetic mechanism and previously validated with experimental data obtained with higher ranges of DBF concentration.