Pyrolysis-catalytic upgrading of brominated high impact polystyrene over Fe and Ni modified catalysts: Influence of HZSM-5 and MCM-41 catalysts

The pyrolysis-catalytic upgrading process of brominated high impact polystyrene (Br-HIPS) was performed using Fe and Ni modified ZSM-5 and MCM-41 catalysts in a two-stage fixed bed reactor. The characterization of catalysts, the product yield and debromination performance in relation to different catalysts were investigated. The results showed that the addition of HZSM-5 and MCM-41 reduced the yield of oil from 69.0 wt % to 64.4 wt % and 62.3 wt %, respectively. The modified catalysts of Fe/ZSM-5 and Ni/ZSM-5 exhibited prominent cracking performance, resulting in the decrease of the oil to 63.2 wt % and 61.2 wt %, respectively, corresponding with an increase of gas products from 7.7 wt % to 16.1 wt % and 20.3 wt %, respectively. However, the mesoporous catalysts of Fe/MCM-41 and Ni/MCM-41 tended to preserve the yield of oil to 65.9 wt % and 65.3 wt %, respectively. In terms of the composition of the oils, a higher yield of single ring aromatics was obtained with Fe modified catalysts, while the addition of ZSM-5 and Ni/ZSM-5 catalysts promoted increased formation of 2 ring aromatics at the expense of single ring aromatics. In addition, the modified catalysts were found to be highly effective at removing bromine from the oils. The Fe modified catalysts exhibited a better debromination performance than Ni modified catalysts, which was in favor of capturing more inorganic bromine and removing bromine from the oils.