Influence of Fe based ZSM-5 catalysts on the vapor intermediates from the pyrolysis of brominated acrylonitrile-butadiene-styrene copolymer (Br-ABS)

The catalytic upgrading of the vapor intermediates from the pyrolysis of brominated acrylonitrile-butadiene-styrene (Br-ABS) was investigated over the Fe/ZSM-5 catalysts in a two-stage fixed bed reactor. Results showed that HZSM-5 and Fe/ZSM-5 catalysts exhibited high catalytic cracking activities, resulting in the increased yield of oil from 62.8 wt% to 64.3 wt% and 66.7 wt%, respectively. When the higher amounts of Fe/ZSM-5 catalysts were applied, the oil yield decreased to 59-61.6 wt%, whereas high amounts of coke were deposited on the catalysts. On the other hand, the higher percentages of the single ring and 2 ring aromatic compounds in the oils was obtained by the Fe/ZSM-5 catalysts, compared to the thermal pyrolysis and the catalytic upgrading by the parent HZSM-5 catalyst. The Fe/ZSM-5 catalysts significantly promoted the formation of styrene monomer and dimer derivatives. It could be proposed that the Fe based materials was in favor of the depolymerization of the polymer matrix, providing the styrene sources for the secondary oligomerization over the parent HZSM-5 catalyst. In addition, the Fe/ZSM-5 catalyst exhibited effective debromination performance, by means of cracking the organobromine compounds and capturing the inorganic bromine in the catalyst. The possible catalytic cracking mechanism over the Fe/ZSM-5 catalyst was discussed.