Catalytic pyrolysis of flame retarded high impact polystyrene over various solid acid catalysts

The catalytic pyrolysis of flame retarded high impact polystyrene (Br-HIPS) was performed in the presence of five different solid acid catalysts in order to remove the bromine from the derived pyrolysis oil. The catalysts were three zeolite materials (HY, Hβ and HZSM-5) and two mesoporous solids (all-silica MCM-41 and active Al2O3). The results showed that in the presence of HY and Hβ zeolites, a reduction of approximate 50 wt.% in oil yield and a corresponding increase in wax and gas yields were obtained compared to thermal degradation. The addition of HZSM-5 showed less impact on product distribution and produced more oil compared with the other zeolites. The mesoporous catalyst of all-silica MCM-41 obtained the highest oil yield of 67.9 wt.% and reduced the wax yield to 8.73 wt.%. In terms of the composition of the pyrolysis oil, HZSM-5 and all-silica MCM-41 were favorable to produce more valuable single ring aromatics, such as toluene, ethylbenzene and cumene. Moreover, the catalysts exhibited pronounced debromination performance, especially the Hβ catalyst, achieving the debromination efficiency of 70.47%. The results confirmed the catalytic pyrolysis of Br-HIPS and debromination performance was well related to the textural properties of catalysts.