STUDY OF THE GAS-PHASE COMBUSTION OF HEXACHLOROBENZENE, INFLUENCE OF THE OXYGEN CONCENTRATION - ATTEMPT AT A GLOBAL KINETIC FORMULATION

This study describes the high temperature (900-1150 degrees C) degrada tion of hexachlorobenzene under oxidative atmospheres with a short res idence time of 2 s. Three concentrations of oxygen are tested (21, 35 and 50% O-2). The experiments are run in stationary conditions. The co mbustion of hexachlorobenzene is nearly complete leading to the format ion of carbon dioxide and molecular chlorine with a conversion approac hing 100% at 1000 degrees C under 21% of oxygen and at 900 degrees C w ith 50% of O-2. The remaining fraction of hexachlorobenzene is close t o few ppm, and some halogenated compounds with lighter molecular weigh t than hexachlorobenzene are present as traces in the exhaust. An atte mpt at a global kinetic formulation is presented. The kinetic evaluati on is performed making the assumption of an overall order of two (one respectively for hexachlorobenzene and oxygen) with an Arrhenius type kinetic rate constant. On this basis, the fitting parameters E-a (acti vation energy) and A (Arrhenius factor) are calculated for the two lim iting concentrations of oxygen, 21 and 50%. (C) 1997 Elsevier Science B.V.