Fast pyrolysis of a waste fraction of high impact polystyrene (HIPS) containing brominated flame retardants in a fluidized bed reactor: The effects of various Ca-based additives (CaO, Ca(OH)2 and oyster shells) on the removal of bromine

A waste fraction of high impact polystyrene (HIPS) containing brominated flame retardants and antimony trioxide (Sb2O3) as a synergist was pyrolyzed in a bench-scale system equipped with a fluidized bed and char separation system. Experiments were carried out to observe the effects of the reaction temperature and three additives (CaO, Ca(OH)2, oyster shells) on the removal of bromine. An analysis of the pyrolysis oils obtained showed the oils were mainly composed of toluene, ethyl-benzene, styrene, cumene, α-methylstyrene, 1,3-diphenylpropane, 1,3-diphenylbutane and (1-bromoethyl)-benzene. When the Ca-based additives were used, the concentration of styrene was markedly increased; whereas, those of ethlybenzene and cumene were reduced. The total bromine content of pyrolysis oil produced without any additive at 459 °C was about 5 wt.%. When Ca(OH)2 and oyster shells were applied, the total bromine contents of the pyrolysis oils were decreased to 1.3 and 2.7 wt.%, respectively. The antimony content in the pyrolysis oil was relatively small due to the efficient operation of the char separation system.