Detailed kinetic modeling of pyrolysis of tetrabromobisphenol A

The thermal degradation of 4,4′-isopropylidenebis(2,6-dibromophenol), commonly known as tetrabromobisphenol A (TBBA), was studied by means of a semi-detailed kinetic model. TBBA is a widely adopted flame retardant. It decomposes in a temperature range between 200 °C and 500 °C, forming gaseous mixtures of HBr and harmful compounds such as bromine-containing phenols, the precursors of brominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). These thermochemical characteristics constitute a significant risk of environmental contamination right throughout TBBA's whole life cycle. A kinetic model based on about 60 components (real and lumped species and radicals) and about 900 reactions satisfactorily reproduces the main aspects of TBBA degradation and volatilization. The model was validated by comparison with several thermogravimetric analyses, both isothermal and dynamic at 10 °C/min. The vaporization of pure TBBA, the formation of hydrogen bromide and of carbonaceous residue were all correctly predicted in quantitative terms right across the entire temperature range. Compared to conventional one-step global apparent degradation models, the proposed model spans much larger operating ranges, especially in predicting the gas phase products distribution. The results are encouraging and confirm the validity of the detailed kinetic model.