The total bromine and antimony contents in the pyrolysis oils were determined using a bomb calorimeter
equipped with an ion chromatograph and ICP-MS after digestion of oil samples, respectively, as shown in Figure
7. During the pyrolysis of Br-HIPS, HBr, SbBr3, Br2 and certain organic brominated compounds were produced.
It should be worth mentioning that the brominated compounds (such as HBr) in the gas products was not
determined by the ion chromatograph. The similar results have been reported by Hall et al. [5] [6]. Additionally,
Figure 7 obviously indicated that there was a high bromine content (7.6 wt%) in each oil product, which means
that large amounts (68.1 wt%) of bromine was transferred to the oil products during the pyrolysis of Br-HIPS
without catalysts. This demonstrated that the effective catalysts or additives were essential for removing bromine
in an attempt to obtain bromine free oil products. When NZ and YZ catalysts were used, the bromine content
in the oils decreased to 2.0 wt% and 1.4 wt%, respectively. This significant decrease of the bromine content
in the oil by YZ catalyst was a consequence of its higher porosity and stronger acidity, contributing to capture
SbBr3 and catalytically crack the organ obrominated compounds [5] [6]. When Fe-NZ and Fe-YZ were used, the
bromine content in the oils decreased from 7.6 wt% to 0.7 wt% and 0.6 wt%, respectively. It indicated that after
the iron oxide loading, the debromination performance of Fe-NZ and Fe-YZ got improved, which was possibly
attributed to the neutralization reaction of loaded iron oxide with HBr derived from the degradation of Br-HIPS
[23]. The neutralization reaction can be shown as following